BSC Technical Manual

HUAWEI

M900/M1800 Base Station Controller Technical Manual

V300R002

M900/M1800 Base Station Controller

Technical Manual

Manual Version T2-030289-20030607-C-4.02

Product Version V300R002

BOM 31020689

Huawei Technologies Co., Ltd. provides customers with comprehensive technical support and service. Please feel free to contact our local office, customer care center or company headquarters.

Huawei Technologies Co., Ltd.

Address: Administration Building, Huawei Technologies Co., Ltd.,

Bantian, Longgang District, Shenzhen, P. R. China

Postal Code: 518129

Website: http://www.huawei.com

Email: [email protected]

Copyright © 2003 Huawei Technologies Co., Ltd.

All Rights Reserved

No part of this manual may be reproduced or transmitted in any form or by any means without prior written consent of Huawei Technologies Co., Ltd.

Trademarks

, HUAWEI, C&C08, EAST8000, HONET, , ViewPoint, INtess, ETS, DMC,

TELLIN, InfoLink, Netkey, Quidway, SYNLOCK, Radium, M900/M1800, TELESIGHT, Quidview, Musa, Airbridge, Tellwin, Inmedia, VRP, DOPRA, iTELLIN, HUAWEI OptiX, C&C08 iNET, NETENGINE, OptiX, SoftX, iSite, U-SYS, iMUSE, OpenEye, Lansway, SmartAX are trademarks of Huawei Technologies Co., Ltd.

All other trademarks mentioned in this manual are the property of their respective holders.

Notice

The information in this manual is subject to change without notice. Every effort has been made in the preparation of this manual to ensure accuracy of the contents, but all statements, information, and recommendations in this manual do not constitute the warranty of any kind, express or implied.

About This Manual

Version

The product version that corresponds to the manual is M900/M1800 BSC V300R002.

Organization of the Manual

The manual consists of 5 chapters that brief the feature, function, performance indexes, hardware structure, software structure, application of BSC.

Chapter 1 is a brief introduction of the product that contains the position and function of BSC, the overview of the hardware and software as well as the main features

Chapter 2 introduces in detail the hardware structure of each module of BSC.

Chapter 3 introduces in detail the software structure of each module of BSC.

Chapter 4 is a brief introduction of system application.

Appendix is about the abbreviation and fundamental knowledge.

Target Readers

The manual is intended for the following readers:

Marketing staff

Installation engineers & technicians

Operation & maintenance personnel

Conventions

This document uses the following conventions:

I. General conventions

Convention Description

Arial Normal paragraphs are in Arial.

Arial Narrow Warnings, cautions, notes and tips are in Arial Narrow.


Bold Headings, Command, Command Description are in boldface.

Terminal Display Terminal Display is in Courier New; message input by the user via the terminal is in boldface.

II. Command conventions


italic font Command arguments for which you supply values are in italics.

[ ] Elements in square brackets [ ] are optional.

{ x | y | ... } Alternative keywords are grouped in braces and separated by vertical bars. One is selected.

[ x | y | ... ] Optional alternative keywords are grouped in square brackets and separated by vertical bars. One (or none) is selected.

{ x | y | ... } * Alternative keywords are grouped in braces and separated by vertical bars. A minimum of one and maximum of all can be selected.

[ x | y | ... ] * Optional alternative keywords are grouped in square brackets and separated by vertical bars. Many (or none) are selected.

! A line starting with an exclamation mark is comments.

III. GUI conventions


< > Message entered via the terminal is within angle brackets.

[ ] MMIs, menu items, data table and field names are inside square brackets [ ].

/ Multi-level menus are separated by forward slashes (/). For example, [File/Create/Folder].

IV. Keyboard operation

Format Description

<Key> Press the key with key name expressed with a pointed bracket, e.g. <Enter>, <Tab>, <Backspace>, or<A>.

<Key1+Key2> Press the keys concurrently; e.g. <Ctrl+Alt+A> means the three keys should be pressed concurrently.

<Key1, Key2> Press the keys in turn, e.g. <Alt, A>means the two keys should be pressed in turn.

[Menu Option] The item with a square bracket indicates the menu option, e.g. [System] option on the main menu. The item with a pointed bracket indicates the functional button option, e.g. <OK> button on some interface.

[Menu1/Menu2/Menu3] Multi-level menu options, e.g. [System/Option/Color setup] on the main menu

Format Description indicates [Color Setup] on the menu option of [Option], which is on the menu option of [System].

V. Mouse operation

Action Description

Click Press the left button or right button quickly (left button by default).

Double Click Press the left button twice continuously and quickly.

Drag Press and hold the left button and drag it to a certain position.

VI. Symbols

Eye-catching symbols are also used in this document to highlight the points worthy of special attention during the operation. They are defined as follows:

Caution, Warning, Danger: Means reader be extremely careful during the

operation.

Note, Comment, Tip, Knowhow, Thought: Means a complementary description.

Technical Manual M900/M1800 Base Station Controller Table of Contents

i

Table of Contents

Chapter 1 System Overview ......................................................................................................... 1-1 1.1 Position of BSC in GSM/GPRS Network ........................................................................... 1-1 1.2 Service and Function ......................................................................................................... 1-1 1.3 System Structure ............................................................................................................... 1-3 1.4 Operating Environment...................................................................................................... 1-3

1.4.1 Physical Features.................................................................................................... 1-3 1.4.2 Power Supply .......................................................................................................... 1-4 1.4.3 Environmental Conditions ....................................................................................... 1-5 1.4.4 Interface .................................................................................................................. 1-6 1.4.5 Capacity .................................................................................................................. 1-6 1.4.6 Clock ....................................................................................................................... 1-7 1.4.7 Reliability ................................................................................................................. 1-7

Chapter 2 Hardware Description.................................................................................................. 2-1 2.1 Overall Architecture of BSC............................................................................................... 2-1

2.1.1 Overview of BSC Architecture................................................................................. 2-1 2.1.2 Functional Blocks of BSC........................................................................................ 2-5

2.2 Types of BSC................................................................................................................... 2-17 2.2.1 Single-module BSC............................................................................................... 2-17 2.2.2 Multi-module BSC ................................................................................................. 2-20

2.3 Modules of BSC............................................................................................................... 2-21 2.3.1 AM/CM .................................................................................................................. 2-21 2.3.2 BM ......................................................................................................................... 2-23 2.3.3 TCSM Unit............................................................................................................. 2-24 2.3.4 BAM....................................................................................................................... 2-27 2.3.5 CDB....................................................................................................................... 2-28

2.4 Functional Frames of BSC............................................................................................... 2-30 2.4.1 Clock Frame.......................................................................................................... 2-30 2.4.2 Main Control Frame .............................................................................................. 2-31 2.4.3 Communication Control Frame ............................................................................. 2-34 2.4.4 Transmission Interface Frame .............................................................................. 2-36 2.4.5 BIE Frame ............................................................................................................. 2-38 2.4.6 TCSM Frame......................................................................................................... 2-41 2.4.7 CDB Frame ........................................................................................................... 2-42 2.4.8 BAM Frame ........................................................................................................... 2-45

2.5 Circuit Boards of BSC...................................................................................................... 2-45

Chapter 3 Software Description................................................................................................... 3-1 3.1 Structure ............................................................................................................................ 3-1

Technical Manual M900/M1800 Base Station Controller Table of Contents

ii

3.1.1 GMPU software....................................................................................................... 3-1 3.1.2 Board software ........................................................................................................ 3-2 3.1.3 OMC software ......................................................................................................... 3-2

3.2 Features............................................................................................................................. 3-3 3.3 GMPU Software and Board Software................................................................................ 3-4

3.3.1 BSC Operating System........................................................................................... 3-5 3.3.2 Database Management System (DBMS).............................................................. 3-13 3.3.3 Software and Data Maintenance........................................................................... 3-16 3.3.4 Radio Resource Management .............................................................................. 3-28 3.3.5 Handover Decision & Power Control..................................................................... 3-34 3.3.6 BTS Management ................................................................................................. 3-36 3.3.7 Operation & Maintenance Management ............................................................... 3-38 3.3.8 Performance Management.................................................................................... 3-40 3.3.9 Alarm Management............................................................................................... 3-43

3.4 OMC Software ................................................................................................................. 3-46 3.4.1 BAM Software ....................................................................................................... 3-46 3.4.2 OMC Shell ............................................................................................................. 3-47 3.4.3 OMC Application Console ..................................................................................... 3-49 3.4.4 OMC Server .......................................................................................................... 3-49

3.5 BSC Operation & Maintenance System .......................................................................... 3-51 3.5.1 System Structure................................................................................................... 3-51 3.5.2 System Features ................................................................................................... 3-52 3.5.3 System Functions.................................................................................................. 3-53

Chapter 4 System Application ..................................................................................................... 4-1 4.1 Principle of System Configuration...................................................................................... 4-1 4.2 Typical Configuration ......................................................................................................... 4-2

Appendix A Power Class ..............................................................................................................A-1

Appendix B Abbreviations ...........................................................................................................B-1

Appendix C Message Flows on Abis & Um Interfaces ..............................................................C-1

Appendix D LAPD and LAPDm Functionality.............................................................................D-1

Appendix E Message Flows on the A-interface .........................................................................E-1

Technical Manual M900/M1800 Base Station Controller Chapter 1 System Overview

1-1

Chapter 1 System Overview

1.1 Position of BSC in GSM/GPRS Network

The position of BSC (Base Station Controller) in the GSM/GPRS network is shown in Figure 1-1.

BTSBSC

PCU

GSM NSS

GPRS NSS

R

OMC SERVERTelnet Terminal OMC Working Station

LAN/WAN

MSC

Figure 1-1 BSC in a GSM/GPRS network

Located between BTS, MSC and PCU in the GSM system, M900/M1800 BSC offers three external interfaces: A-interface, Abis interface and Pb interface. A-interface is an open interface, Pb and Abis interfaces are Huawei-developed interfaces. Complying respectively with ETSI GSM08.08, ETSI GSM04.08 & ETSI GSM08.58 and Huawei’s Pb interface protocol and compatible with the specifications of GSM PHASE 1, GSM PHASE 2 and GSM PHASE 2+ protocols.

M900/M1800 BSC mainly performs radio resources management, BTS management, power control, handover control, traffic statistics, etc. It plays a pivotal role in radio access and network optimization.

1.2 Service and Function Support GSM900, GSM1800 frequency band as ETSI GSM protocol mentioned.


1-2

Provide all functions for BTS supervision, which is stipulated in the GSM standard protocols. Self-designed intelligent algorithms ensure the reliability especially SDCCH dynamic allocation. Location updating, call connection, short message, message on demand and SMS-based WAP use the signaling channels and their traffic is gradually increased. The SDCCH dynamic allocation function enables the real time dynamic adjustment of the SDCCH and TCH ratio depending on the radio environment, and improved Quality of Service (QoS) as a result.

Support the broadcasting of short messages in the cell. Weather reports, advertisements, stock, banking, traffic information can be transmitted to MS through broadcast control channel.

Support smooth channel assignment during the call set-up requested to or from the MS.

Call handling, supports Full Rate (FR) and Enhanced Full Rate (EFR) voice coding. It also offers Very Early Allocation (VEA), Early Allocation (EA) and Off-air Call Set Up (OACSU) mode.

Support discontinuous transmission (DTX) and Voice Activity Detection (VAD) implementation.

Encryption is used for ciphering and deciphering of information to and from an MS over a dedicated resource to provide security. Encryption is used or not by BTS but BSC provides this control.

Provide paging queuing and call queuing function. With the help of different parameters and reports monitors the states and status of

radio channels. To reduce the radio channel interference and maximum network utilization it

supports both baseband and synthesizer hopping. Traffic statistic reports are used to increase the system efficiency and helps in

network optimization. High integration of TC supports all standard services, and also support TFO

function. To provide a continuous conversation when roaming is the core objective of a

cellular network. When a user moves from one BTS to another, the call is handed over to a new BTS so that there will be no interruption.

Support hierarchical cellular network structure. The radio network is divided into 4 layers, each layer can be divided into 16 priorities to control the traffic distribution.

Power Control is an important feature to improve the transmission quality by reducing interference. It also prolongs the battery lifetime.

Operation and maintenance: Powerful tools on management, which provides easy maintenance of OMC-R link, BTS and BSC fault management through OMC or local terminal.

OMC-R support Dynamic Data Configuration for BSS, which provides GUI interface for Data configure.

Data configuration and BTS smooth software down loading.


1-3

Support 16Kbit RSL and OML on Abis interface Support star, tree and chain on Abis interface for site connection with E1.

1.3 System Structure

The overall structure of the BSC system is shown in Figure 1-2. It falls mainly into five parts: CDB, BAM, BM, TCSM and AM/CM.

E1

E1

Opt. fiber

BM1

TCSM BAM

BSC alarm box

E1 HDLCE1

HDLC

HDLC

LAN

BSC

CDB

BMx

MSCPCU OMC

BTSyBTS1

E1E1

BTSyBTS1

BTS central alarm box

SMC

AM/CM

1≤x≤81≤y≤64

Figure 1-2 Structural diagram of multi-module BSC system

1.4 Operating Environment

1.4.1 Physical Features

I. Dimensions and Structure

The external dimension of BSC is shown in Figure 1-3.


1-4

Alarm indicator

a) Single cabinet & its dimensions b) Combined cabinets

Figure 1-3 Cabinet dimensions (unit: mm)

The external dimension of a single cabinet:

Height 2100mm Width 800mm Depth 550mm

Note: The single cabinet is 880mm in width and 800mm wide when standing side by side with other cabinets as shown in Figure 1-3.

The mechanical structure of the BSC is based on the “building-block” design, which makes installation easy and flexible.

Using the state-of-the-art mechanical processing techniques and surface treatment, it exhibits strong environment adaptability.

The BSC cabinet also provides good electromagnetic shielding effect.

II. Cabinet Weight & Floor Bearing Capacity Requirements

The maximum static weight of a single cabinet is 310kg.

The weight-bearing capacity of the equipment room should be 450 kg/m2.

1.4.2 Power Supply

I. Power supply range

The power supply range for the BSC that operates on 48V DC is: -40~-57V DC.


1-5

II. Power consumption

The power consumption of each module in the BSC is as follows:

AM/CM: 500W. One BM: 350W. TCSM frame: 1320W (6 frames). Power consumption in full configuration (1024TRX): 3300W (TCSM rack not

included).

1.4.3 Environmental Conditions

I. Grounding requirements

Combined grounding resistance 1 Ohm.

II. Temperature and Humidity

Normal operating temperature: 150C~350C.

Safe operating temperature: 00C ~450C.

Normal operating humidity: 30%~65%.

Safe operating humidity: 10%~90%.

III. Room cleanliness

The dusts in the equipment may produce electrostatic adherence, resulting in poor contact of the metal connectors. This will not only affect the life of the equipment but also lead to faults. The requirements for the dust content and particle size in the equipment room are shown in Table 1-1.

Table 1-1 Requirements for dust content and size in equipment room

Max. Diameter (3m) 0.5 1 3 5

Max. contents (particles/m3) 14 % 105 7 % 105 24 % 104 3 % 104

The dust particles are non-conducting, magnetic-inductive and non-corrosive.

Apart from the requirements for dust content and size, there are also strict requirements for the hazardous air-borne salt, acid and sulfide, which will speed up the metal erosion and aging process of some components. In the room, such harmful gases as SO2, H2S, NH3, NO2, etc. shall be shielded and restrained as shown in Table 1-2.


1-6

Table 1-2 Harmful gas restrictions

Gas Name Mean (mg/m3) Maximum (mg/m3) SO2 0.2 1.5 H2S 0.006 or so 0.03 NO2 0.04 0.15 NH3 0.05 0.15 Cl2 0.01 0.3

IV. Room lighting

Direct exposure to the sunshine should be avoided to guard against component aging and deforming. The average illumination shall be 300~450LX with no glare.

V. Atmospheric pressure

1.08%105 to 5.1%104 pa (-500mm to +500mm).

VI. Air pollution

No erosive gas or smog is allowed in the room. Smoking is not allowed in the room. 5 Performance Indices

1.4.4 Interface

The Abis interface utilizes the standard E1 interface.

The Pb interface utilizes the standard EI interface.

Standard A-interface ensures the interconnection and interworking with the equipment of other manufacturers.

Using the standard E1, the A-interface supports 120 ohm and 75 ohm cables.

Providing max. 64 Pb ports (after multiplexing) and 256 A ports (the Abis interface can connect 512 BTSs), 16 SS7 signaling ports and 1536 LAPD ports.

BS interface equipment (BIE board): provides 15:1 (TRX:E1) multiplexing and supports star, chain, tree, ring and hybrid networking of BTS.

1.4.5 Capacity

Supporting a capacity of maximum 1024 TRXs / 512 BTSs / 1024 cells.

Supporting a maximum traffic of 6400Erl

BHCA: 800K


1-7

1.4.6 Clock

Stratum 3 clock is provided, with the following indices:

Clock precision: ±4.6%10-6 Pull-in range: ±4.6%10-6 Maximum frequency deviation: 2%10-8/day Initial maximum frequency deviation: 1%10-8

1.4.7 Reliability

MTBF (Mean Time Between Failures): 341298 hours

MTTR (Mean Time To Repair): 1 hours

Availability: 99.9997%

Average annual system down time: 0.26 hours

Technical Manual M900/M1800 Base Station Controller Chapter 2 Hardware Description

2-1

Chapter 2 Hardware Description

2.1 Overall Architecture of BSC

2.1.1 Overview of BSC Architecture

The hardware system of the M900/M1800 base station controller adopts a modular structure, and can be divided into four modular levels, as shown in Figure 2-1.

The lowest level is composed of various circuit boards. Various circuit boards are combined together to form frame units. Each frame unit accomplishes the specific functions.

Frame units with various functions are combined together to form a module, and respective modules can implement specific functions independently.

Different modules are combined together to form the base station controller.

BSC

Modules

Functional Frames

Circuit Boards

BSC

Figure 2-1 900/M1800 BSC modular architecture

The modular design makes the installation and expansion of BSC convenient and flexible i.e., new functions and technologies can be introduced by just addition/removal of functional frames.


2-2

Application of very large scale integrated circuit (VLSI) in circuit designing gives a compact and highly reliable system with low power consumption.

Hardware design is simplified due to the application of microprocessors and programmable logic chips. To enhance functions, it is only required to add corresponding hardware and software.

I. Types of BSC

BSC can be divided into multi-module BSC and single-module BSC. The functional composition and the modular composition of the BSC are shown respectively in Table 2-1.

Table 2-1 BSC types

BSC types Functional description Modules

Multi-module BSC When BSC has more than 128TRXs, it is called multi-module BSC, and AM/CM is required. The quantity of BMs depends on a specific capacity. 8 BMs can be configured at the most.

AM/CM BM

BAM TCSM CDB

Without SMUX

When BSC has only 128TRXs or less, only one BM needs to be configured. The AM/CM is not required. Only one basic cabinet and a extension cabinet are required for BSC without SMUX.

BM BAM

TCSM CDB Single-mo

dule BSC

With SMUX When BSC has only 128TRXs or less, only one BM needs to be configured. The AM/CM is not required. Only one basic cabinet is required for BSC with SMUX.

BM BAM

TCSM CDB

II. Modules

The module functions and cabinet composition are shown in Table 2-2.

Table 2-2 BSC modules

Modules Function description Functional frames

AM/CM Designed only for multi-module BSC, the AM/CM, a center for BSC speech channel switching and information exchange, accomplishes inter-modular communication between BMs.

Communication control frame Transmission interface frame Clock frame

BM BM performs mainly such functions as call handling, signaling processing, radio resources management, radio link management and circuit maintenance.

Main control frame BIE frame Clock frame (when there is no AM/CM in BSC)

TCSM TCSM implements the transcoding / rate adaptation and sub-multiplexing functions. TCSM frame

Cell Broadcast Database (CDB)

Linked with the short message center, the CDB module is a traffic processing center, supporting the broadcast short message service.

CDB frame

Back Administration Module (BAM)

BAM is a bridge between BSC and OMC. The latter conducts the operation & maintenance of BSC via BAM. BAM frame


2-3

III. Functional Frames

The functional frames, their functions and circuit boards are listed in Table 2-3.

Table 2-3 BSC functional frames

Functional frames Function description Circuit boards

Clock Frame The clock frame phase-locks upper-level MSC or BITS clock reference resources and provides the AM/CM and BM with stable clock sources.

Clock Board (GCKS) Power Control Board (PWC)

Main Control Frame The main control frame carries out management and control of the BM, communication between AM/CM and signaling processing.

Main Processing Unit (GMPU) GMPU Switchover Board (GEMA) Master Node Board (GNOD) Memory Board (GMEM) Module Communication 2 Link (GMC2) Optic Fiber Interface Board (GOPT) Alarm Board (GALM) SS7 Signaling Processing Board (LPN7) Link Access Protocol Processing Board (GLAP) Switching Network Board (GNET) Power Control Board (PWC)

Communication Control Frame

The communication control frame is the control center of AM/CM. The communication control unit mainly manages and controls the system.

Inter-module Communication Board (GMCCS) Signaling T-network Board (GSNT) Central T-network Board (GCTN) Alarm Board (GALM) Power Control Board (PWC)

Transmission Interface Frame

The transmission interface frame implements multiplexing/demultiplexing of inter-modular speech channels and signaling links, optic-electric conversion and E1 interface driving so that the inter-modular communication messages can be transmitted on the optical fiber.

Fiber Communication Board (GFBI) Enhanced E3 Sub-multiplexer (E3M) Power Control Board (PWC)

TCSM Frame The TCSM frame fulfills the functions of transcoding / rate adaptation and sub-multiplexing.

Transcoding Board (FTC) Sub-Multiplexer (MSM) Power Control Board (PWS)

BIE Frame Designed for the BM, the BIE frame presents an Abis interface in between BSC and BTS.

BS Interface Board (BIE) Power Control Board (PWC) Sub-Multiplexer Interface Board (SMI)

CDB Frame The CDB frame, a traffic processing center, supports the broadcast short message service.

The CDB is physically a Windows NT computer, occupying half of the frame.

Back Administrative Module Frame (BAM Frame )

The BAM frame is a bridge between BSC and OMC. The latter performs the operation & maintenance of the BSC via OMC.

The BAM is placed in the BAM frame as standalone equipment.

IV. Circuit Boards

The circuit boards used in the BSC are shown in Table 2-4. Logic board is created by loading some software on the physical board, so varying logic boards may share the same physical boards.


2-4

Table 2-4 BSC circuit boards

Logic board Physical board Function description

BIE BIE A transmission interface board between BSC and BTS, Provides E1 interface and multiplexing/demultiplexing functions.

E3M E3M Integrating sub-multiplexer functions, the E3M offers externally 4 E1 interfaces to connect the PCU and TCSM frames. It carries out receiving, sending, switching, HDLC link control and multiplexing/demultiplexing of 5-E1 signals.

GFBI FBI GFBI provides optical paths for inter-modular communications in collaboration with GOPT in the BM.

GALM GALM GALM provides a hardware interface for room environment alarms, collecting temperatures, humidity and fire alarms, etc.

GCTN CTN The GCTN is a speech channel switching center of AM/CM. In the multi-module BSC, GCTN is mainly designed for network switching and equipment control.

GCKS GCKS The GCKS board, a high-level reference clock source generation board, is designed mainly to provide the equipment with a superb clock source.

GSNT SNT The GSNT switches the inter-modular signals and the internal messages of AM/CM, and delivers loading paths for modules.

GMCCS GMCC GMCCS provides a signaling communication link between BM and AM/CM, transfers control messages from BM to BM, from BM to GMCCM and from BM to GCTN, and presents a serial port for maintenance.

GMCCM GMCC GMCCM controls the entire AM/CM and provides an interface with BAM.

GMEM GMEM Located in the main control unit of the BM, the GMEM is a data storage board, which serves mainly for network communications.

GNET GNET The GNET implements the function of intra-module speech channel switching.

GMPU GMPU GMPU, a central processing unit in the module, conducts active/standby switchover via GEMA and operates in hot backup mode.

GNOD GNOD The GNOD is responsible for the communication of GMPU with other frames.

GEMA GEMA The GEMA is an Emergency Message Automatic Transmission System. It communicates with two GMPUs and controls their switchover.

LPN7 LAP LPN7 handles SS7 signaling on the A-interface.

GLAP GLAP The GLAP is a LAPD protocol processing board. The LAPD signaling at the Abis interface and Pb interface is processed by the GLAP.

GMC2 GMC2 The GMC2 is an inter-module communication processing board of BM.

GOPT GOPT GOPT is the physical bearer for the communication between BM and AM/CM.

DRC DRC The DRC presents E1 interfaces in collaboration with E3M, and coupling and over-voltage protection modules, etc. The DRC is plugged on the backplane.

FBC FBC FBC collaborates with GFBI to accomplish electric-optic conversion and optic-electric conversion of 40.96Mbit/s signals.

FTC FTC The FTC is mainly designed for coding/decoding of speech signals, data format conversion and rate adaptation as well as transparent transmission of SS7 signaling.

MSM (TCSM frame) MSM The MSM performs the multiplexing/demultiplexing function in

multi-module BSC.

SMI (BIE frame) SMI The SMI performs the multiplexing/demultiplexing function in single-module BSCs.

PWC PWC A power board, whose power is 100W, supplies power to each board in the frame.


2-5

Logic board Physical board Function description

PWS PWS A power board, whose power is 300W, supplies power to each board in the TCSM frame and bears an emergency serial port.

2.1.2 Functional Blocks of BSC

According to the functions, the BSC can be divided into control system, switching network, TCSM unit, Base Station Interface Equipment (BIE), clock synchronization system, alarm system, Back Administration Module (BAM) and Cell Broadcast Database (CDB).

A functional structure of the BSC system is shown in Figure 2-2.

BAM

Alarmsystem

BTS MSCTCSM E1 interface

Clocksynchronizationsystem

Switchingnetwork

BIE

Control system

OMC

CDB

Figure 2-2 Functional structure of BSC system

I. Control System

The M900/M1800 BSC works on distributed processing and centralized control principles.

A single-module BSC has only one BM and no AM/CM, GOPT or inter-module communications function. In terms of structure and control system, the single-module BSC is a subset of a multi-module BSC so we will focus on the multi-module BSC, which is illustrated in Figure 2-3.


2-6

GMCCM

GMCCS GMCCS GMCCS GMCCS GMCCS

GMCCM

GMCCS GMCCS GMCCS GMCCS GMCCS

16 digit parallel bus

SNT

GSNT

GMPU

GMC2

GOPT

GFBI

LAP/LAPD

GMPU

GMC2

GOPT

GFBI

AM/CM

GNET GNET

GNOD GNOD

LAP/LAPD

SNT

GSNT

GMPU

GMC2

GOPT

GFBI

LPN7/GLAP

GMPU

GMC2

GOPT

GFBI

GNET GNET

GNOD GNOD

LPN7/GLAP

Optical fiber

BM8BM1

Figure 2-3 Functional blocks of control system

1) System structure

The control system is mainly composed of processor circuit, inter-module communication circuit, intra-module communication circuit, signaling switching circuit and signaling processing circuit, etc.

Main processing boards refer to the GMCCM of AM/CM and GMPU of BM.

Inter-module communication circuit includes the GMCCS in AM/CM and the GMC2 in BM.

Intra-module communication circuit: The communication within the AM/CM module is accomplished by GMCCS, and GNOD mainly accomplishes the communication within BM module.


2-7

Signaling switching circuit is mainly responsible for signaling switching control, here signaling refers to various control and state information. In the AM/CM module, GSNT accomplishes the signaling switching function, and in the BM module, GNET accomplishes that function.

Signaling processing circuit mainly refers to LPN7 (LAP) and GLAP.

2) Communication routes

The data channels for the communication between modules of the multi-module BSC are composed of the GMCCM and GMCCS in the AM/CM, and GMPU & GMC2 in the BM, as shown in Figure 2-4.

The communication messages among modules mainly include management data, call handling messages, maintenance & testing messages, loaded programs & data, traffic statistics, etc.

GMCC S

AM/CM

GMC2

BM1 Module

Data Bus

GMCC S GMCC S GMCC S

GMC2 GMC2 GMC2 GMC2

BM2 Module BM8 Module

GMC2

GMCCM

GMPUGMPU GMPU

Figure 2-4 Communication between modules

As illustrated in Figure 2-4, the GMC2 of a BM is responsible for the two-channel HDLC inter-module communication, and the GMCCS of AM/CM is responsible for multi-channel HDLC inter-module communication.

All possible inter-module communication routes are shown in Figure 2-5.


2-8

GMCCS

BMa AM/CM

BMc

HDLCHDLC HDLC HDLC

Dual port Dual port Dual port Dual port

AM/CM

Data bus

optical fiber

(c) Communication between BM and AM/CM

(a) Communication between two BMs that have direct links with the same GMCCS

(b) Communication between two BMs that do not have direct links with the same GMCCS

BMa

AM/CM

BMbBMa

GMPU GMPU GMPU GMPU

GMC2 GMC2 GMC2 GMC2

GMCCM

GMPU GMC2 GOPT GFBI GMCCS GMCCM

Data bus

GMCCM

GMCCS GMCCS

Figure 2-5 Inter-module communication routes

Communication between GMPU and GMC2 in the BM and that between GMCCM and GMCCS in the AM/CM module are conducted through dual-port buffer (mail box), while the communication between GMC2 and GMCCS is through the HDLC link.

GMC2 and GMCCS communicate through optical fiber. GOPT and GFBI are their respective optical fiber interfaces.

Each BM houses two GMC2 boards which communicate with two GMCCS boards respectively, thus improving reliability. The two GMCCS boards communicate with corresponding GMC2 boards of BM in load sharing mode. On the failure of one link, the second link will take over the full load automatically, which ensures the system reliability.

The physical layer of inter-module communication is achieved by optical fibers and HSCX (High level Serial Communication Controller with extended feature and functionality). The data link layer is fully compliant with X.25 LAPD protocol.

The transfer layer is realized by GMCCS, and the transmission layer and application layer are accomplished by GMCCM and GMPU software.


2-9

II. Switching Network

The GCTN of AM/CM and the GNET of BM provide a large-capacity T-T-T switching network, and jointly accomplish the switching of speech information, as shown in Figure 2-6.

A GCTN provides 16k%16k T switching network and a GNET of BM is a single 4k%4k T switching network.

GCTN

GFBI GFBI

GOPT

NET

GNET

BIE BIE

AM/CM

BM1GOPT

NET

GNET

BIE BIE

BM8

E3M

BTS BTS BTS BTS

PCUTCSM

E1E1

Optical fiber

BSC

Figure 2-6 Switching network structure of multi-module BSC

The switching network of the single-module BSC is much simpler, as shown in Figure 2-7 (including TCSM). It only has 4k%4k T switching network boards (GNET) in BM, which independently implements the switching of speech information, etc.


2-10

GNET

BIE BIE

SMI

BTS BTS

BM

TCSM PCU

BSC

Figure 2-7 Switching network structure of the single-module BSC

III. TCSM Unit

Generally, TRAU and SMUX are integrated in one unit called TCSM, its position is shown in Figure 2-8. For single-module BSC where sub-multiplexing is not needed, TCSM is often used although it has no SMUX.

The TCSM unit accomplishes the function of transcoding/rate adaptation and sub-multiplexing.

In PSTN, Pulse Code Modulation (PCM) is used for normal speech, with a rate of 64kbit/s. In GSM system, RPE-LTP or CELP coding with much lower rate (16kbit/s) is used due to the limitation of radio resources. If a subscriber of fixed network wants to access a GSM subscriber, then there is a need of code conversion and this conversion is done by TRAU.

Since the rate of each channel in existing terrestrial lines is 64kbit/s, it is a waste if one channel is used to carry one 16kbit/s GSM channel. To save terrestrial line resources, sub-multiplexer (SMUX) is used between MSC and BSC to multiplex 4%16kbit/s channels to transmit four speech channels through one terrestrial line channel.


2-11

E3M TCSME1 E1 X 4

GDTMBSC MSC

Figure 2-8 Position of TCSM in the system

When the multiplexing mode is adopted between BSC and MSC, the TCSM unit is put on the MSC side physically to save the transmission lines between BSC and MSC by multiplexing the lines between E3M (or SMI) and TCSM.

When the multiplexing mode is not introduced between BSC and MSC (in the case of single-module BSC), the TCSM unit is put on the BSC side.

BSC delivers a standard A-interface to MSC via the TCSM unit. The A-interface, a standard E1 interface physically, can interconnect with MSCs of other manufacturers.

IV. Base Station Interface Equipment (BIE)

The interface between BTS and BSC is called BIE. It provides a standard E1 interface, and mainly accomplishes functions like BTS access, channel multiplexing on Abis interface, etc. Each E1 interface can supports up to 15 TRXs (15:1).

The position of the base station interface equipment in system is shown in Figure 2-9.

BIE/TMU

E1

BIE

BTS

BSCE1

PCUL2PU: Layer2 Processing Unit

L2PU

Figure 2-9 Position of BIE in system

V. Back Administration Module (BAM)

BAM serves as a communication bridge between BSC and OMC. Via BAM, OMC can perform operation and maintenance over BSC.

BAM communicates with the control system through HDLC link, and forms Local Area Network (LAN) or Wide Area Network (WAN) together with the OMC system. When BSC and OMC are in the same premises, BAM and OMC can be connected through


2-12

LAN, and in case of long distance, these can be connected through WAN with the help of network adapter, router and transmission equipment.

The position of BAM in the system is shown in Figure 2-10.

R

BAM

BSC

BSS

Router

Router

Router

Telnet Terminal

OMC

Operation & Maintenance Interface

Backbone Network

Figure 2-10 Position of the BAM in the system (WAN configuration)

VI. Clock Synchronization System

The BSC clock synchronization system phase-locks the upper-level MSC or BITS clock as reference source, and provides a stable clock source for the AM/CM and BM.

1) System features

The BSC clock synchronization system has the following features:

The clock can be synchronized by Phase-lock Loop (PLL) and by software, so that the clock of the system can follow the MSC or BITS clock reliably.

BSC clock uses international stratum 3 clock which provides a reliable clock source for the system.

Clock system is equipped with perfect display, alarm, maintenance and operation system, and internal parameters of the clock can be set through OMC directly.

2) System structure

Both small and multi-module BSCs extract, "purify", and synthesize the clock synchronization signals from the MSC/BITS reference sources. But they have quite different clock synchronization system structures, as shown in Figure 2-11 and Figure 2-12.


2-13

GCTN

GSNT

GMCC GALM

GFBI

GOPT

GNET

BIE BIE

GMPUGMC2

AM/CM

MSC reference source

BITS reference source

BM

Clock frame

GMPU

Figure 2-11 Clock synchronization system structure of the multi-module BSC

In a multi-module BSC, the synthesized clock synchronization signals are sent to GCTN and GSNT, and then to other units/parts of the AM/CM. The BM's GOPT extracts clock signals from optical signals and generates required clock synchronization signals. These signals are sent to GNET, which will forward the signals to other parts of the BM.

Clock Frame

BIE

MSC Reference Source

BITS Reference Source

GNETGMPU

BIE

Figure 2-12 Clock synchronization system structure of single-module BSC


2-14

In a single-module BSC, the synthesized clock synchronization signals are directly sent to GNET, which then sends these signals to other parts of the BM.

3) System control

The clock synchronization system is configured in the clock frame that contains two GCKS boards in hot backup mode.

In multi-module BSC, the OMC communicates with GMCC through BAM, and the GMCCM implements the maintenance and operation over 2 GCKS boards via two serial ports. In this way, the OMC can operate and maintain the clock synchronization system.

In single-module BSC, the OMC communicates with GMPU through BAM, the GMPU communicates with GALM through HDLC link, and GALM communicates with GCKS through serial port. In this way, the OMC can implement the operation and maintenance of the clock synchronization system.

The clock control methods for the clock synchronization systems in multi-module and single-module BSCs are shown in Figure 2-13 and Figure 2-14 respectively.

GMCCM

GMCCM

GCKS GCKS

BAM OMC

Serial port Serial port

Figure 2-13 Clock synchronization control of multi-module BSC

OMCBAM

GCKS GCKS

GALM

GMPU

GMPU

HDLC

Serial port Serial port

Figure 2-14 Clock synchronization control of single-module BSC


2-15

VII. Alarm System

The M900/M1800 BSC alarm system collects various alarm messages and forwards them to the GMPU for classification and processing, then these alarms are sent to the alarm box and OMC alarm console respectively.

The whole alarm system is composed of the alarm box, OMC alarm console, alarm communication board, etc.

There are two alarm boxes connected to the BSC, one is for the BSC and the other is centralized alarm box for the BTS, responsible for the centralized audible and visible alarms of all BTSs managed by that BSC.

The structures of the multi-module and single-module BSC alarm systems are shown in Figure 2-15 and Figure 2-16 respectively.

GMPU

GALM

Collection of Equipment Room Environment Alarm Switching Values

GMC2

BAM

OMC Alarm Console

GALM

AM/CM

BM

BSC Alarm Box

Collection of Secondary Power Alarms

Collection of Secondary Power Alarms

GMCCM GMCCS

BTS Centralized Alarm Box

Secondary Power Alarm

Secondary Power Alarm

Equipment Room Environment Alarm

Figure 2-15 Alarm system structure of multi-module BSC


2-16

GMPU

GALM Environment alarm switch value collection

BAM OMC alarm console

Row/column alarm indicator

BSC alarm box

Secondary power alarm collection


Figure 2-16 Alarm system structure of single-module BSC

In a multi-module BSC, the BM's GMPU and AM/CM's GMCCM collect alarm information of the system software/hardware, which is sent to the OMC alarm console and alarm box.

In a single-module BSC, the BM's GMPU collects alarm information of the system software/hardware, which is sent to the OMC alarm console and alarm box.

GALM provides the hardware interfaces for equipment room environmental alarms. It collects alarms including temperature, humidity, fire, and secondary power supply alarms. These alarm messages are also sent to the OMC alarm console and alarm box.

VIII. CDB

Cell Broadcast Database (CDB) is a traffic processing center, responsible for providing the interface between the Short Message Center (SMC) and BSC, and supporting short message broadcast service. Its server communicates with the GMEM boards of the modules through the Ethernet interface.

In M900/M1800 BSC, CDB is a centralized database. Each BM communicates with CDB via Ethernet interface provided by a GMEM board, as shown in Figure 2-17.


2-17

GMEM

GMPU

BM1

GMPU

BM2

GMPU

BMn

...

CDBServer

Ethernet

AM/CM

GMEM GMEM

1 ☯ n ☯ 8

Figure 2-17 CDB networking structure

2.2 Types of BSC

As BSC is the central part of BSS, it acts as a concentrator for the links between the Abis- and A- interfaces.

2.2.1 Single-module BSC

One of the most powerful features of M900/M1800 BSC is its modular approach. If only 128 TRXs or 64 BTSs are required, then there is no need to install Administration Module / Communication Module (AM/CM) along with related equipment. Single Basic Module (BM) is enough, as illustrated in Figure 2-18.


2-18

BM

E1 E1 E1

BAMTCSMBSC

SMC

BTSyBTS2BTS1

BM

E1 E1 HDLCHDLC

HDLC

CDB

LAN

OMCMSCPCU

BSC alarm box


1≤y≤64

Figure 2-18 Hardware structure of single-module BSC

A single-module BSC has only one BM and no AM/CM, GOPT or inter-module communications function. In terms of structure and control system, the single-module BSC is a subset of a multi-module BSC, which is our next topic for discussion.

A standard 2100%800%550 mm cabinet can hold six frames and is used to install BM and other related equipment. A BM cabinet has six frames, numbered 0-5 from bottom to top, including main control frame (frames 1 & 2), clock frame (frame 3) and BIE. BAM is installed in the frame 0 of the main BM cabinet.

If there is no SMUX configured in the single-module BSC then two cabinets, basic and extension cabinets are needed. And if it contains SMUX, only one basic cabinet is required. If CDB is configured, it can be put in the extension cabinet.

I. Single-module BSC without SMUX

When there is no multiplexing equipment between MSC and BSC, the basic cabinet holds one clock frame, one TCSM frame and one BIE frame in addition to the main control frame. If one TCSM frame is insufficient, it is necessary to install an extension cabinet where the additional TCSM frame is placed. If BSC is to implement the cell broadcast function, a CDB frame shall also be added to the extension cabinet. For the configuration, refer to Figure 2-19.

Only FTC board but not MSM board is plugged in the TCSM frame.


2-19

UPS FAN

Frame 5

Frame4

Frame3

Frame2

Frame1

Frame0TCSM Frame

Active CDB

Empty Frame

UPS FAN

TCSM Frame

BIE Frame

Clock Frame

Main Control Frame

Basic Cabinet

BAM Frame

Empty Frame

Empty Frame

Empty Frame

Standby CDB

Extension Cabinet

Figure 2-19 Configuration of single-module BSC cabinet (without SMUX)

II. Single-module BSC with SMUX

When there is multiplexing equipment between MSC and BSC, the basic cabinet takes one clock frame and two BIE frames in addition to the main control frame. If BSC is to implement the cell broadcast function, it is necessary to add an extension cabinet where the CDB server is placed, as shown in Figure 2-20.

The SMI is plugged in the BIE frame, connecting to the MSM in the TCSM frame. The two BIE frames serve to accommodate respectively the BS interface equipment and SMUX. The TCSM unit is configured on the MSC side, occupying a whole cabinet.


2-20

UPS FAN

Frame 5

Frame4

Frame3

Frame2

Frame1

Frame0ActiveCDB

StandbyCDB

Empty Frame

UPS FAN

BIE Frame(SMI)

Clock Frame

Main Control Frame

Basic Cabinet

BAM Frame

BIE Frame (BIE)

Empty Frame

Empty Frame

Empty Frame

Empty Frame

Extension Cabinet

Figure 2-20 Configuration of single-module BSC cabinet (with SMUX)

2.2.2 Multi-module BSC

For multi-module BSC which supports more than 128 TRXs, AM/CM module is required. The hardware structure of multi-module BSC is shown in Figure 2-21.

E1

E1

Opt. fiber

BM1

TCSM BAM

BSC alarm box

E1 HDLCE1

HDLC

HDLC

LAN

BSC

CDB

BMx

MSCPCU OMC

BTSyBTS1

E1E1

BTSyBTS1


SMC

AM/CM

1≤x≤81≤y≤64

Figure 2-21 Hardware structure of multi-module BSC


2-21

In multi-module BSC, 8 BMs can be configured at the most. Each BM can support 64 BTSs or 128 TRXs, i.e. M900/M1800 multi-module BSC can support up to 512 BTSs or 1024 TRXs at the most, which is the ultimate solution for large cellular networks.

A multi-module BSC has multiple BMs and one AM/CM. Eight BMs can be installed in four BM cabinets, and AM/CM is configured in AM/CM cabinet. Each cabinet has six frames, numbered 0-5 from bottom to top. AM/CM cabinet contains clock frame (frame 5), communication control frame (frame 4), transmission interface frame (frames 3&2), CDB (frame 1) and BAM in frame 0. Since clock frame, BAM and CDB are installed in AM/CM cabinet, the only equipment to be installed in BM cabinet is main control frame and BIE.

For alarm prompts, external alarm boxes, including BSC alarm box and BTS centralized alarm box, shall be installed.

UPS FAN

UPS FAN

Frame 5

Frame4

Frame3

Frame2

Frame1

Frame0BAM

ActiveCDB

StandbyCDB


CommunicationControl Frame

Clock Frame

AM/CM Cabinet BM Cabinet

UPS FANUPS FAN

BIE Frame

Main Control Frame

BIE Frame

BIE Frame

Main Control Frame

BIE Frame

UPS FAN

UPS FAN

TCSM Frame

Main Control Frame Main Control Frame

BM Cabinet

TCSM Frame

TCSM Frame

TCSM Frame

TCSM Frame

TCSM Frame

TCSM Cabinet

Figure 2-22 Configuration of multi-module BSC cabinet

2.3 Modules of BSC

2.3.1 AM/CM

AM/CM module is the center of speech channel switching and message switching of multi-module BSC.

AM/CM module is mainly composed of communication control unit, central switching network, transmission interface unit, clock synchronization system and alarm system. The structural diagram is shown in Figure 2-23.


2-22

GMCC0

2kx2k GSNT0

NT1

16 K×16 K GCTN0

Thick line: Speech channel HW, 32.768MThin line: signaling HW, 2.048M

16- bit Parallel Bus

GCKS

FS 32M

HDLC

HDLC

HDLC

GALM

GFBI0 GFBI 1 GFBI k-1 GFBI k GFBI nGFBI n-1

To BMn

GCTN1

GMCC1

GMCC2

GMCC3

GMCC10

GMCC

11

GS

BAM

4M

HDLC RS422 Serial Port

BSC Alarm Box

BM#1 BM#K BM#N

32M

8K

Figure 2-23 Functional blocks of AM/CM system

I. System composition

AM/CM module is mainly composed of communication control unit, central switching network, transmission interface unit, clock synchronization system, alarm system and back administration module.

The communication control unit manages and controls the whole system. It is mainly composed of GMCCM (GMCC0-1), GMCCS (GMCC2-11) and GSNT.

The central switching network mainly handles speech channel switching between BMs. The function of central switching network is accomplished by GCTN board.

Transmission interface unit mainly responsible for multiplexing/demultiplexing of inter-module speech channels and signaling links, optic-electric conversion and E1 interface driving, so that inter-module communication messages can be transmitted over optical fibers. Transmission interface unit is mainly composed of GFBI and E3M. GFBI provides the optical interface from AM to BM module, E3M provides E1 interface from BSC to TCSM unit.

Clock synchronization system provides standard stratum 3 clock for the whole BSC system. Functions of clock synchronization system are mainly accomplished by the GCKS in clock frame.

Alarm system collects alarms and drives the alarm box. The alarm system of AM/CM is mainly composed of the GALM and the alarm box.


2-23

II. Communication modes

Three kinds of communication modes are used in AM/CM: mailbox, serial port, and HDLC.

Mailbox mode is employed for the communication among GMCC boards via the data bus.

Each GMCC (including GMCCM and GMCCS) can provide 2 serial ports. GMCCM communicates with GCKS, and GMCCS communicates with GFBI through these 2 serial ports. GALM communicates with BSC alarm box through RS422 serial port.

GMCCM communicates with GCTN, GSNT, GALM boards and BAM through HDLC link.

GMCCS communicates with E3M, GCTN boards and GMC2 (BM) through HDLC link.

GMCCS communicates with GMC2 in the BM through HDLC link.

2.3.2 BM

BM is the basic unit of M900/M1800 BSC. It handles most of the functions of call handling, signaling processing, radio resources management, radio link management and circuit maintenance.

I. System structure

BM is mainly composed of main control unit, switching network, base station interface equipment and alarm system, as shown in Figure 2-24. When BSC does not have AM/CM, the clock synchronization unit is also installed in the BM.

Modu

le T

switc

hing

netw

ork

Module main control

unit

To Central T NET of AM/CM

Network Control & Clock

Interface equipmentBTS

BM

Figure 2-24 Functional blocks of BM system (Multi-module BSC)


2-24

The main control unit mainly accomplishes the management and control over BM module, communication with AM/CM module and signaling processing. It is mainly composed of GMPU, GNOD, GMEM, GMC2, GOPT, GALM, LPN7 and GLAP.

The switching network accomplishes the switching of timeslots in the module, which is mainly handled by GNET board.

Base station interface equipment (BIE) can multiplex/de-multiplex the transmitted signals.

The alarm system is designed to collect alarms and drive the alarm box. The collected alarm messages can either be reported to OMC or sent directly to the external alarm box (used in single-module BSC). The BM alarm system consists mainly of the GALM boards.

II. Communication modes

There are three major communication modes within the BM, which are mailbox, serial ports and HDLC.

The GMPU communicates with other boards in the main control frame through the bus in mailbox mode.

The GMPU communicates with GNOD through mailbox, while each GNOD provides 4 serial ports for the communication with non-main control frame devices such as BIE board.

GMC2 communicates with GMCCS in AM/CM module via HDLC link.

Note: This mode applies to the multi-module BSC only, a single-module BSC has no AM/CM.

2.3.3 TCSM Unit

TRAU and SMUX are usually integrated in one unit called TCSM, i.e. TCSM handles both rate adaptation and multiplexing.

In multi-module BSC, functions of TRAU are accomplished by FTC boards, functions of SMUX are accomplished by MSM and E3M together. The frame to insert FTC board and MSM is called TCSM frame. Four MSM boards and sixteen FTC boards can be inserted in 1 TCSM frame. In real application, the configuration of TRAU is necessary while SMUX is optional.

I. TRAU

Pulse Code Modulation (PCM) is used for normal speech in PSTN, at a rate of 64kbit/s whereas in GSM, RPE-LTP or CELP coding with much lower rate (16kbit/s) is used due


2-25

to the limitation of radio channel resources. If a subscriber of PSTN network wants to access a GSM subscriber, then there is a need of code conversion. This conversion is completed by Transcoder & Rate Adapter Unit (TRAU).

The main functions of TRAU are, to perform coding/decoding on speech signal and rate adaptation to realize the communication between GSM subscribers and PSTN subscribers. In addition, TRAU can also accomplish the rate adaptation of digital signals and transparent transmission of SS7 signaling on A-interface.

The position of the TRAU in the GSM system is shown in Figure 2-25.

BSC MSCTRAUA interface

Figure 2-25 TRAU in the GSM system

In M900/M1800 BSC, the functions of TRAU are accomplished by FTC board.

1) Speech service

The most fundamental function of TRAU is to encode and decode voice. Regular Pulse Excitation Long Term Prediction (RPE-LTP) algorithm is used. TRAU frames the speech signals received from MSC in one frame per 20 ms. One frame of speech data includes 160 PCM sampling points, 1280 bits in total, the encoded output parameters are 260 bits altogether (EFR service adopts CELP algorithm, the encoded parameters are 244 bits altogether). After the addition of synchronization bits and command words, TRAU frame has 320 bits. The reverse process of coding is called decoding. After receiving TRAU frame from BSC, TRAU will restore it to speech data by decoding algorithm and send to the MSC.

TRAU adopts discontinuous transmission (DTX) technology to minimize the power consumption of BTS and MS, and to reduce the co-channel interference of radio interface.

Voice activity detection (VAD) is used together with SID (Silence Descriptor) technique in the discontinuous transmission (DTX) mode of GSM.

If TRAU detected that there is no speech information in the data received from MSC through VAD functional module, it will clear voice flag in the encoded TRAU frame. After BTS identifies this flag bit, downlink transmission will be disconnected till the flag resets.

In the same way, TRAU will also identify SID flag at the reception of uplink frame. When SID flag is reset, it indicates that MS is in the interval of emission.


2-26

To make the subscribers feel that GSM network is still in service, TRAU adopts the substitution technology to insert comfortable noise in uplink to avoid the impression of interrupted communication.

In MS-MS conversation, the encoding/decoding function of TRAU may be omitted, as it causes the degrading of voice quality.

By canceling the encoding\decoding function (i.e. Tandem Free Operation, TFO), the voice quality can be improved.

The TFO function is implemented by FTC board through inner signaling communication to reduce the times of encoding\decoding during MS-MS conversation.

2) Data service

GSM system provides various services for subscribers, which are defined and classified into telephony and data services. For telephony services, the transferred information is speech signals within audio range, for data services, signals other than voice are transferred, e.g. text, image, fax, various messages, computer files, etc.

TRAU determines current service operation type by detecting the TRAU frame format command word sent from base station.

During data service communication, TRAU accomplishes the format converting of data frame and rate adaptation without transcoding transferred data.

3) Signaling timeslot

In TRAU, each FTC board is responsible for one PCM stream (32 timeslots in each PCM stream), where timeslot 0 is for transferring frame synchronization signals. Signaling timeslot may be assigned through OMC randomly.

FTC board forwards the content of signaling timeslot transparently so that signaling information will not be affected.

II. SMUX

To save terrestrial line resources, Sub-multiplexer (SMUX) is used between MSC and BSC to multiplex 4%16kbit/s channels to carry four speech channels through one terrestrial line channel. No matter speech signals or data, they are transferred with a rate of 16kbit/s between the BSC and TRAU.

The position of SMUX in the system is illustrated in Figure 2-26, where TCSM consists of MSM and FTC boards.

In multi-module BSC, the functions of SMUX are accomplished by MSM and E3M board. While in a single-module BSC, this function is implemented in the MSM plugged in the TCSM frame and the SMI plugged in the BIE slot.


2-27

FTCFTC FTC FTC

MSM

HW

E1

BSC

E1

TCSM

MSCSMI/E3M

SMUX

Figure 2-26 Position of SMUX in the system

SMUX has the following functions.

Multiplexing/demultiplexing speech channels: SMUX can multiplex 4 channels into 1 standard E1 link and demultiplex 4 channels from 1 standard E1 link.

Transparent transmission of signaling: SMUX can transparently transfer signaling.

Operation and maintenance link: MSM and E3M boards can communicate with each other through HDLC link, which occupies the last two bits of 31st timeslot on E1 link. BSC can operate and maintain the remote TCSM units through this HDLC link.

2.3.4 BAM

I. Functions

Back Administration Module (BAM) helps customers to maintain and operate BSC through OMC. It forwards the maintenance and operation commands from OMC to BSC system and sends back the system response to the corresponding OMC terminal. It also stores and forwards alarm messages, traffic statistics data, etc.

BAM keeps normal communication with GMPU during operation. In case of any abnormality in BAM software, it can restart within preset time.

BAM communicates with control system through HDLC link, and communicates with OMC directly or indirectly via network adapter. When BSC and OMC are in the same premises, then BSC can communicate with OMC directly through network adapter. When BSC and OMC are not in the same premises, they communicate through network adapter, router and transmission equipment.

II. System structure

BAM is connected with the BSC through 2Mbit/s HDLC link and with the O&M terminal via the LAN or WAN. A structural diagram is shown in Figure 2-27.


2-28

PI

TNI

MCP

BAM

BSC

Peripheral

Terminal Network System

HDLC

Figure 2-27 BAM structure

The BAM is composed of three major parts, which are: Peripheral Interface (PI), Terminal Network Interface (TNI) and MCP.

Through Peripheral Interface (PI), various devices can be handled such as dual CD-ROMs, hard disk array, printer and tape drive used to dump or hard copy of data.

With TNI, terminal systems (maintenance, test, traffic statistics and data setting systems) can form a LAN attached with network servers to provide 10Mbit/s to 100Mbit/s transmission links, and to extend the network through devices such as network bridge/router, achieving data sharing in a larger scope. In M900/M1800 BSC, this interface is directly or indirectly connected to OMC.

MCP is the PC card for the communication between BAM and BSC. Each card provides two 2Mbit/s HDLC links to connect with BSC, serving as the message paths between BSC and BAM.

III. Structure features

When BAM software is abnormal, BAM will reset and restart automatically, thanks to BAM self-restoring capability.

All components have passed the electromagnetism compatibility test.

-48V standard industrial power supply is used, in consideration that BAM is installed on the cabinet in actual application. -48V power supply is highly reliable, stable and safe. The power supply has passed the electromagnetic compatibility test.

BAM can be installed inside the cabinet. The outer surface of the cabinet is painted, while the inner surface is not, so as to make sure good grounding effect. There are ventilation openings at the front of the cabinet, together with various indicators, buttons, keyboard and monitor ports.

2.3.5 CDB

Cell Broadcast Database (CDB) is a traffic processing center, responsible for providing the interface between the Short Message Center (SMC) and BSC, and supports short message broadcast service. Its server communicates with the GMEM boards of the


2-29

modules through Ethernet. CDB can communicate with CBC through either TCP/IP or X.25 interface. To support X.25 interface, a X.25 card should be added to CDB for communication with CBC.

I. Cell broadcast system

Short Message Service Cell Broadcast (SMSCB) allows short message to be broadcast to all mobile stations in certain areas. These areas may be one or several cells, even the entire PLMN area. Short message from cell broadcast center (CBC) is sent to the CDB of BSC which manages the message. BSC then sends the received message to BTS. BTS can make load control.

The functions of cell broadcast system is briefly described as follows:

Able to explain and response to the message primitives from CBC. Able to report to CBC about CBCH channel state and the conditions of message

sending. Reporting error information to CBC when received message primitives can not be

understood or executed. Able to report cell fault to CBC. BSC sends overload indication of related cell to CBC when the frequency of CBC

message is beyond the load of BSC. Storage and management of cell broadcast short message. Supporting DRX mode. Arrangement of cell broadcast short messages in CBCH channel and sending

them to BTS.

II. Database structure

CDB contains three parts, which are message library, cell data table and general control table.

Message library mainly stores the cell broadcast short message sent from CBC and currently being broadcast in BSC, including message flag, message serial number, message coding method, transmitting frequency, message sending request, message contents etc.

Cell data table mainly stores broadcast channel configuration message and message related to broadcast short message for each cell of current BSC, including cell state, state and configuration of CBCH channel, storage arrays of broadcast short message, sending queue of broadcast short message etc.

General control table mainly stores, controls and records related information about cell broadcast of current BSC, including connection information with BM module, connection information with CBC, parameters of BSC cell broadcast, etc.


2-30

III. CDB features and performance

CDB supports the storage and management of 300 broadcast short messages.

Each cell can hold 60 broadcast short messages.

CDB supports the flow control of broadcast short message between CBC and itself.

CDB supports message flow control between BTS and itself.

CDB supports DRX mode.

CDB supports the forwarding of broadcast short messages among several modules. If there is some error in GMEM of a BM, CDB can send the message to another BM through another working GMEM.

For more information about CDB, please refer to M900/M1800 Cell Broadcast System User Manual.

2.4 Functional Frames of BSC

2.4.1 Clock Frame

The clock synchronization system of BSC operates in the clock frame.

The clock frame phase-locks the upper-level MSC or BITS clock reference sources and provides the AM/CM and BM with stable clock sources. The clock stratum of the clock frame can set flexibly to Stratum 2 clock or Stratum 3 clock through data configuration. M900/M1800 BSC uses Stratum 3 clock system.

Clock frame configuration is shown in Figure 2-28.

Configured with active/standby GCKS boards in hot backup (two boards), one clock frame outputs active/standby clocks (two clocks) and sends them to GCTN and GSNT.

In a single-module BSC, the GCKS communicates with the GMPU via the GALM board. In multi-module BSC, GCKS communicates with the GMCCM directly.


2-31

0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25

PWC

BIE

PWC

GCKS

GCKS

Figure 2-28 Clock frame in full configuration

The clock reference source is input via the backplane interface of the clock frame to the GCKS board. GCKS locks and pulls-in the reference source by software phase-locking and generates clock signals identical in frequency and phase with the reference source.

In a multi-module BSC, the synthesized clock synchronization signals are sent to GCTN and GSNT, and then to other units/parts of the AM/CM. The BM's GOPT extracts clock signals from optical signals and generates required clock synchronization signals. These signals are sent to GNET, and then forwarded to other parts of the BM.

In a single-module BSC, the synthesized clock synchronization signals are directly sent to GNET, which then sends these signals to other parts of the BM.

Both PWC and GCKS operate in 1+1 redundant mode to ensure the reliable operation of the clock frame.

2.4.2 Main Control Frame

I. Functional Blocks

The main control frame is designed to implement management and control of the BM, communications with AM/CM, signaling processing, etc.

The main control unit is mainly composed of the processor circuits, signaling processing circuits, inter-module communication circuits and database interface circuits.

Three-level distributed control is adopted in the BM, with GMPU, GNOD and slave nodes (CPUs) from top down, as illustrated in Figure 2-29.


2-32

Inter-modulecommunication

Main control unit GMPU (A) GEMA GMPU (B)

GNOD

CPU CPU

GNOD

GOPT

GMC2

LP

G

AP

GMEM

GALM

LN7

Figure 2-29 Hierarchical structure of the main control unit

For internal communication, mailbox mode is employed between the first and the second level CPUs, while the master node/slave node high-speed serial communication mode of point-to-point or point-to-multipoint is employed between the second and third level CPUs.

GMPU is the central processor in the main control unit of the BM. To improve the system reliability, two GMPU are used in hot backup mode.

The GEMA is used to help GMPU data backup and to control the GMPU switchover.

Active/standby GMPUs are determined by GEMA, forming the first level control system.

GMPU directly controls GNET via the bus, and exchanges messages with GNOD, LPN7, GMEM and GLAP via mailbox communication mode. These boards in the main control unit constitute the second level control system.

GMPU sets up the connection with respective functional slave nodes via GNOD. Here, slave node refers to the microprocessor on functional circuit board (such as BIE board). GNOD communicates with CPUs on related circuit boards via serial ports and controls respective CPUs in master/slave node communication mode.

The CPUs accommodated in respective control interface ports in the BM cooperate with each other, forming a functional multi-processor control system. The inter-processor communication is conducted through the mailbox by using memory mapping technology, which greatly reduces the overhead for internal communication.


2-33

The processor circuit mainly consists of GMPU, GEMA and GNOD. Among them, GMPUs are the central processing units in the module, whose active/standby state is controlled by the GEMA. Both GMPUs work in redundant mode and communicate with slave nodes via GNOD.

The processing of SS7 signaling on A-interface is implemented by LPN7. GLAP is responsible for signaling on Abis interface and Pb interface.

Inter-module communication circuit mainly consists of GMC2 and GOPT. (Note: There is no inter-module communications circuit in the single-module BSC.)

The BSC is connected with CDB through GMEM.

II. Frame Configuration

The main control frame in full configuration is shown in Figure 2-30. The boards that can be installed in it are as follows:

GMPU GNOD GMEM GMC2 GOPT GALM LPN7 GLAP PWC GEMA GNET CKV


2-34

0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25

PWC

GNOD

PWC

GNOD

GNOD

GNOD

GNOD

GNOD

GLAP

GLAP

GMC2

LPN7

0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25

PWC

GMPU

PWC

GNOD

GNOD

GNOD

GNOD

GNOD

GLAP

GLAP

GOPT

GLAP

GLAP

GEMA

GMPU

GNET

GNET

GMEM

LPN7

GMC2

GALM

GOPT

CKV

CKV

Figure 2-30 Main control frame in full configuration

In multi-module BSC, two GOPTs and two GMC2s should be configured in the main control frame.

The GOPT connects with the AM/CM via optical fiber.

The GMEM works only when the cell broadcast service is in operation.

2.4.3 Communication Control Frame

The communication control frame is the control center of the AM/CM. The communication control unit manages and controls the overall system.


The functional blocks of the communication control frame are shown in Figure 2-31.


2-35

GMCCM GMCCS GMCCS GMCCS

GSNTGALM BAM

GCTN

HDLC

HDLC HDLC

HDLC

Bus

Communication Control Frame

Figure 2-31 Functional blocks of communication control frame

The GMCCM communicates with GCTN, GALM and BAM through GSNT. It provides signaling communication links for the BM and AM/CM, and transfers control messages from BM to BM, from BM to GMCCM, from BM to GCTN and from BM to TCSM unit. The GMCCM also processes the maintenance messages of all the boards in the AM/CM and clock frame. It also controls the GSNT in its provision of loading paths for the BM and AM/CM, but it is not responsible for the switching control of the overall system.

The GMCCS communicates with GCTN and BM via the HDLC link. The GMCCS provides signaling communication links for the BM and AM/CM and transfers control messages from BM to BM, from BM to GMCCM, from BM to GCTN and from BM to TCSM unit.

The GSNT, a signaling switching center of AM/CM, performs switching of signaling messages between boards in the AM/CM, and provides loading paths to the modules.


The communication control frame in full configuration is shown in Figure 2-32. The boards that can be installed in it are as follows:

GMCC GSNT GALM


2-36

PWC

0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25

GMCC9

GMCC8

GMCC7

PWC

GALM

GSNT

GSNT

GMCC2

GMCC1

GMCC0

PWC

GMCC5

GMCC4

GMCC3

GMCC6

Figure 2-32 Communication control frame in full configuration

The communication control frame occupies one frame space and accommodates 10 GMCC boards in full configuration. The GMCC boards are numbered from right to left. GMCC0 can only be plugged in Slot 16 and GMCC1 only in Slot 15. The right-most two GMCC slots hold GMCCM boards. The other GMCC slots hold GMCCS boards (at most 8 GMCCS boards can be configured).

2.4.4 Transmission Interface Frame

Transmission interface frame mainly accomplishes the functions of multiplexing/ demultiplexing of inter-module speech channels and signaling links, optic-electric conversion and E1 interface driving, so that inter-module communication messages can be transmitted over optical fibers.

Transmission interface unit is mainly composed of GFBI/FBC, GCTN, E3M and DRC.


The functional blocks of the transmission interface frame are shown in Figure 2-33.


2-37

GFBI

:GFBI

E3M

E3MTCSM

:

GCTN

Signal HW

Signal HW

Signal HW

Signal HW

E1

E1


Optic Fiber

MSM

TCSMMSM

BMGOPT

BMGOPT

:

Optic Fiber

Figure 2-33 Functional blocks of transmission interface frame

The transmission interface frame uses GCTN as the center for speech channel switching.

Each BM connects with the GFBI via two pairs of optical fibers. The GFBI extracts and separates 32Mbit/s speech channel signals from the optical path signals and sends them to the GCTN, and then separates 2.048Mbit/s signals and sends them to the GSNT of the communication control frame for processing. In addition, it combines the speech channel signals from the GCTN and the link signals from the GSNT into 40.96Mbit/s stream and sends them to the FBC.

The E3M connects with GCTN via 32Mbit/s HW. It fulfils the switching from super HW (512 timeslots) to 16 E1s, compresses these 16 E1s into 4 E1s by 4:1, thus greatly reduces transmission lines. It provides 4 Pb ports to the PCU. The speech channel signals are sent to the MSC after switching by GCTN and E3M.

The DRC board, in collaboration with the E3M, provides the external E1 interface coupling and over-voltage protection modules. The DRC is installed on the backplane.


The boards that can be installed in the transmission interface frame are as follows:

GFBI E3M PWC GCTN

The transmission interface frame in full configuration is shown in Figure 2-34.


2-38

0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25

PWC

PWC

E3M

GQS I

0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25

PWC

GFBI

GFBI

GFBI

GFBI

PWC

GFBI

GFBI

GFBI

GFBI

GCTN

GCTN

E3M

E3M

E3M

E3M

E3M

E3M

E3M

E3M

E3M

E3M

E3M

E3M

E3M

E3M

E3M

Figure 2-34 Transmission interface frame in full configuration

The transmission interface frame occupies two frame spaces.

GCTN, a central speech channel switching system of AM/CM, occupies two slots. The two GCTNs work in active/standby mode and implement 16k%16k speech channel switching.

The FBC and GFBI are used in pairs. The FBC is plugged in the socket on the backplane of the AM/CM interface frame, in one-to-one correspondence with the GFBI board.

Featuring optical interface and conversion functions, the GFBI splits the optical fiber signals between BM and AM/CM into 32Mbit/s super HW signaling and 2Mbit/s HW signaling. The GFBI collaborates with the GOPT in the BM to provide paths for inter-modular communications.

The E3M performs the timeslot switching of 2k network and E1 multiplexing function.

Four PWCs are configured, fixed in positions.

2.4.5 BIE Frame


Located in the BM cabinet, the BIE frame provides Abis interface between BSC and BTS. The BIE of BSC includes the BS interface device BIE and the transparent transmission BIE (responsible for transmitting SS7 signaling transparently to E3M).


2-39

The two boards are identical in hardware and compatible in slot, with the only difference of DIP switch settings.

The BIE boards installed in the BIE frame work in active/standby group. There is no association between different working groups.

The functional blocks of the BIE frame are shown in Figure 2-35.

PWC

Power Supply in the Frame

B I E(Active)

B I E(Standby)

Transparent Transmission

B I E

G N E T

E 3 M

B I E(Active)

B I E(Standby)

:

Working Unit 7

:

BTS0

BTS7

HW E1

BIE Frame

E1

E1HW

HW

Working Unit 0

BIE Frame

Figure 2-35 Functional blocks of BIE frame

BIE performs transcoding, re-timing, control, hot backup and signal multiplexing. The BIE is a transmission interface device between BSC and BTS. Operating in active/standby (1+1) mode, the BIE provides the largest convergence ratio (15:1) of the Abis interface and supports star, chain, tree and hybrid topologies for BTS networking. It connects BTS to BSC in a flexible way to minimize the E1 links between BSC and BTS.


The boards in the BIE frame are:

BIE PWC

The BIE frame in full configuration is shown in Figure 2-36.


2-40

0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25

PWC

BIE

PWC

BIE

BIE

BIE

BIE

BIE

BIE

BIE

BIE

BIE

BIE

BIE

BIE

BIE

BIE

BIE

BIE

BIE

Figure 2-36 BIE frame in full configuration

There are two kinds of BIE boards in the BIE frame: one is the BIE that transmits transparently SS7 signaling and the other is the general BIE that establishes connection between BSC and BTS. The only difference of these boards is their DIP switch settings.

The BIE boards are numbered from left to right starting from 0. The two adjacent BIE boards operate in active/standby state. The number of active/standby groups depends on the number of configured boards. There are a variety of BIE active/standby combinations in 1+1 redundancy mode:

Slot 2 and Slot 3 (group 0)








Slot 23 stands alone with no active/standby relationship, but its active/standby group number is still defined as 8.

When the quantity worked out by BIE is N, the total number of slots required is 2%N-1.


2-41

2.4.6 TCSM Frame


The FTC and MSM can be plugged in the TCSM frame. The Transcoder & Rate Adapter Unit (TRAU) and Sub-Multiplexer (SMUX) are jointly called TCSM unit. Every 4 FTC boards and 1 MSM make up a TCSM unit. A TCSM frame can hold 4 TCSM units. Each unit works independently without any correlation. One TCSM frame can hold 4 MSM boards and 16 FTC boards. Configuration of TRAU is compulsory while SMUX is optional.

In multi-module BSC, the functions of TRAU are implemented by the FTC and multiplexing is accomplished by MSM and E3M in the transmission interface frame.

The functional blocks of the TCSM frame are shown in Figure 2-37.

E1

FTC FTC FTC FTC

MSM

TCSM Unit 0

FTC FTC FTC FTC

MSM

TCSM Unit 3

E1

E1

TCSM Frame

To MSC SideTo BSC Side

To BSCTo MSC Side

E1

HW

HW

Figure 2-37 Functional blocks of TCSM frame


On the backplane of the TCSM frame there are TCB boards. The boards that can be installed in the frame are as follows:

FTC MSM PWS

The frame in full configuration is shown in Figure 2-38.


2-42

0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25

PWS

BIE

PWS

FTC

FTC

FTC

FTC

MSM

FTC

MSM

FTC

FTC

FTC

MSM

FTC

FTC

FTC

FTC

FTC

FTC

FTC

FTC

MSM

Figure 2-38 TCSM frame in full configuration

The TCSM frame can be placed on the MSC side (with multiplexing) or on the BSC side (without multiplexing).

2.4.7 CDB Frame


The Cell Broadcast Database (CDB), a traffic processing center, supports cell broadcast short message service.

The CDB connects with the Cell Broadcast Center (CBC) via LAN or WAN for command interactivity and response transceiving. In addition, the CDB connects to the GMEM corresponding to the BSC and implements such procedures of BTS as CBCH channel query, CBS message transmission and flow control via the BSC.

The CDB network interface is shown in Figure 2-39.

BSCCBC

CDB GMEM BMLANLAN/WAN

Figure 2-39 CDB network interface

The major software functional modules of the CDB are comprised of CBC command interface module, GMEM interface module, CBS message storage module, CBS message scheduling module, CBS message transmission module, flow control module, network interface module, and protocol conversion module. When TCP/IP is adopted for the communication between CDB and CBC, the protocol conversion module is not


2-43

needed, as shown in Figure 2-40. When X.25 protocol is adopted for the communication between CDB and CBC, the protocol conversion module is used to convert different protocols, as shown in Figure 2-41.

CDB

CBC CommandInterface CBS Message Storage

CBS MessageScheduling

Flow Control

Network Interface

GMEM Interface

CBS MessageTransmission

CBC

BM

GMEM

Ethernet

Figure 2-40 CDB functional blocks (using TC/IP)

CDB

CBC

BM

GMEM

WAN ÍøX.25

CBC CommandInterface CBS Message Storage

CBS MessageScheduling

Flow Control

Network Interface

GMEM Interface

CBS MessageTransmission

Ethernet

Protocol Conversion

Figure 2-41 CDB functional blocks (using X.25 protocol)

The CBC command interface module handles command interactivity between CDB and CBC.


2-44

The CBS message storage module is designed to store the CBS messages to be sent or not sent completely.

The CBS message scheduling module is designed to process the majority of operation requests of CBC, schedule CBS messages and generate schedule messages under the discontinuous reception (DRX) mode.

The CBS message transmission mode serves to send the CBS messages to BTS.

The GMEM interface handles command interactivity between CDB and BSC, forwards the internal operation commands of the CDB to BSC, which in turn transmits transparently these messages to the BTS.

The flow control module exercises flow control over the CBCH.

The network interface module, which establishes connections directly with external network, is responsible for receiving and transmitting messages.

The protocol conversion module converts the TCP/IP data packets sent from CDB to CBC into X.25 data packets, and converts the packets received by X.25 card into TCP/IP data packets and sends them to CDB.


There is no backplane in the CDB frame. The CDB, a sub-module of BSC, is physically a computer running on Windows NT, occupying a half frame. Installed generally in the lower part of the AM/CM cabinet of BSC, it fulfills mainly the cell broadcast functions supported by BSC.

The position of CDB in the AM/CM cabinet is shown in Figure 2-42.

Clock Frame 5

Communication Control Frame 4

Transmission Interface Frame 3

Transmission Interface Frame 2

CDB 1

BAM Frame 0

Figure 2-42 Position of CDB in AM/CM cabinet


2-45

2.4.8 BAM Frame

Refer to the description of BAM.

2.5 Circuit Boards of BSC

In this section we will briefly discuss the circuit boards of M900/M1800 BSC to have an overall understanding. For details, refer to M900/M1800 BSC Hardware Description Manual.

Technical Manual M900/M1800 Base Station Controller Chapter 3 Software Description

3-1

Chapter 3 Software Description

3.1 Structure

The BSC software consists of three major parts: GMPU software (also called Host software), board software and OMC software. Figure 3-1 is a schematic diagram of BSC software distribution.

GMPU

OMC Software

Software Running Entity

GMPU Software

Board Software

WS

WS Software

BAM

BAM Software



LPN7 Other BoardsBIE. . .

OMC Server

OMC Server Software

Figure 3-1 Relations between BSC software and running entities

Note:

Only BAM software is a part of BSC software while the WS software and OMC Server software are part of the operations & maintenance software. For the sake of integrity, the WS software and OMC Server software are also included in the BSC software.

3.1.1 GMPU software

The GMPU software refers to the software that runs on the GMPU of the BM. It implements such functions as BSC hardware resources control, signaling processing, radio resources management and interface management.


3-2

3.1.2 Board software

The board software refers to the software that runs on FTC, BIE, MSM, LPN7, GLAP, etc. It implements the interface functions and protocol processing between the data link layer and the network layer.

The GMPU software communicates and exchanges information with the board software through the Inter-Procedure Communication (IPC) protocol using the mailbox mode and memory mapping technology. They cooperate with an appropriate division of workload to guarantee high reliability and high processing capability of the system.

3.1.3 OMC software

The OMC software provides such functions as maintenance, data configuration, traffic statistics and alarm management of the BSC.

As per its physical distribution, the OMC software falls into the parts as follows:

I. BAM software

The BAM software carries out two functions: one is to send the operation & maintenance command from the OMC system to the BSC and directs the response of the BSC system to the OMC terminal, acting as a bridge between OMC and the BSC system, the other is to serve as a server in the Client/Server network model. BAM can be used as a maintenance server for near-end maintenance of BSC.

Besides managing the database as well as test tasks and traffic statistic tasks, BAM stores and forwards alarm messages, traffic statistic data, etc. It can store all the vital data on the hard disk and dump them to CDs or OMC server if necessary.

II. OMC Server software

The OMC Server runs on SUN Solaris. The number of OMC servers depends on the capacity of the system.

The OMC network configuration data and user data are stored in the OMC server. Other data like alarm data, traffic statistic report data is also stored in the OMC server. Sybase is used as database platform.

The OMC Server and application consoles are the Server terminal and Client terminal end respectively in the Client/Server model.

III. WS Software

The OMC WS is a direct interface where maintenance and management of GSM NEs is conducted. It is a simple PC running on the Windows operating system. The software


3-3

that runs in it consists of OMC Shell and client programs of various application consoles:

OMC Shell serves to browse and view the configuration state and node information on the OMC network and monitors OMC network. The operating environment for the OMC Shell is WINDOWS 9.x or WINDOWS NT.

The application console is a classified set of some service functions, including data management, maintenance, test, alarms, performance measurement, etc. A user can perform all the operations available in the OMC system on the application consoles.

All the maintenance & management operations can be performed on one WS or separately on multiple WSs. The number of WSs depends on the capacity of the system.

The OMC WS sends the operation & maintenance command to a specific maintenance module in the BSC via the OMC Server and BAM, requests the current running state from the BSC or requests the BSC to perform some operation for the real-time monitoring and control. On receiving the operation & maintenance command, the operations & maintenance module in the BSC acquires the current running states of the BSC and sends them to the OMC WS.

BSC organizes all the data required for the operation of the management system using the distributed relational database to guarantee flexibility, consistency and scalability. This eliminates the bottleneck resulting from the centralized database and ensures high-efficiency operation of the system.

3.2 Features

The software system of the BSC is modularly designed, having distributed control structure and centralized database. It performs channel management, handover decision and power control functions by using dynamic control algorithm.

OMC software runs on a Client/Server architecture. There are two Client/Server Models in the OMC part. BAM serves as a server for near-end maintenance of BSC while OMC Server as a server for application consoles.

The BSC software system has excellent expandability. Handover decision and power control functions are performed by GLAP. Software optimization helps to enhance the processing capability of the GMPU, which ensures a reliable functioning of multi-module BSC.

The software system of the BSC has strong protections against errors. Functions like LAPD mutual assistance and carrier frequency mutual assistance are developed and implemented to enhance the error tolerance of the BSC system software. Fully backup protection, flow control, and resource check ensure the system reliability.


3-4

The software system of BSC provides rich O&M functions, which are enabled via the interaction between the OMC and the BSC system software. The system also provides visual graphic interfaces through OMC, which helps to monitor the network and in case of any abnormality, take spontaneous actions. It provides dynamic data configuration through which maintenance staff can block a device without affecting current subscribers’ calls.

The GMPU software can be loaded from the BAM into the memory of the GMPU boards and backup software can be stored in the Flash Memory of GMPU. The board software is stationed in the CPUs of boards. During system upgrading, the related software can be loaded through OMC without affecting the normal operations of other parts. This ensures rapid and easy upgrading of software version.

The essential parts like GNET, BIE, etc., operate in a board-level hot backup mode and the corresponding software supports hot backup and immediate switchover to ensure system reliability and service quality.

3.3 GMPU Software and Board Software

The GMPU software and board software manage jointly the hardware resources of BSC and deliver such functions as signaling processing, radio resources management and interface management.

The overall structure of the BSC GMPU software and board software is shown in Figure 3-2.

RRCall management

Channel management

A interface

BTSM

Abis interfaceDBMS

SCCP

MTP

LAPD

RR: Radio Resources Management BTSM: Base Transceiver Station Management

OS: Operating System

LAPD: Link Access Protocol on D channelSCCP: Signaling Connection Control PartDBMS: Data Base Management System

MTP: Message Transfer Part

OS

Pb interface

Handover decisionPower control

Figure 3-2 BSC software architecture


3-5

3.3.1 BSC Operating System

The BSC operating system consists mainly of five parts: task management, message management, memory management, time limit management and initial booting and recovery.

I. Task management

A task is the program unit that can be dispatched by the operating system and executed by the CPU. A task is also called a process. Task management is designed on the basis of tasks' dynamic, concurrent and asynchronous correlative nature. This definition can be used to clearly describe the logic of relative programs corresponding to the functions of BSC.

The system software tasks of BSC can be classified as communication tasks, resources management tasks, call handling tasks, database management tasks and maintenance tasks. These tasks are running under the coordination and management of the BSC operating system.

1) Task state

As an "executable program unit", each task has its dynamic states. There are four states for tasks in the BSC, which are “executing”, “ready”, “suspended” and “dormant”.

Executing a task means that resources of the CPU are currently occupied and its program logic is being executed. The CPU can execute only one task at a time, i.e. only one task can be in the “executing” state.

When the task for execution is well prepared, it is in the "ready" state.

When a task is waiting for the dispatch by the system i.e. in queue (before the occurrence of an event), it is in the suspended state.

Dormant tasks refer to those that are not initialized or have been deleted by the system.

The state transition of the task in the BSC is shown in Figure 3-3.

Executing

Ready

Dormant Suspended

Delet

e

Create

Delete

Delete

Event o

ccurs

Disp

atch

Time s

lice

Wait

in su

spen

sion

Figure 3-3 Task state transition in the BSC operating system


3-6

2) Task dispatch

Task dispatch strategy used in the BSC operating system is "seizure dispatch" and is based on the priority levels of tasks and events. Ready tasks of higher priority levels seize the resources of the CPU first, and tasks of the same priority levels are dispatched according to the sequence of their readiness. In the BSC system, when a task is generated, it is provided with a priority value in the range of 0-255. The smaller priority value shows higher priority level, i.e., 0 represents the highest priority level of the system.

When a task T1 of higher priority is suspended due to its waiting for resource and the resource is being occupied and not released by task T2 of lower priority, a priority inversion occurs, which means that a task of higher priority is delayed by a lower priority task. In a system that is driven by the priority dispatch strategy, T1 can only wait for the slow dispatch and executions of T2 (slow due to its low priority) and can not be activated until the occupied resource is released. In this case, execution time of the higher-priority T1 can not be guaranteed. To solve this problem, the BSC operating system adopts the priority inheritance technology. Once a task of higher priority is blocked by a task with lower priority, the task of lower priority can be upgraded to a proper higher level so that it can be quickly executed and hence release the resources urgently needed by the task of higher priority.

When a task of lower priority is executed and a task of higher priority is ready due to the occurrence of an event, the task of higher priority in the ready state can interrupt and suspend the task of lower priority and therefore seize the control over CPU.

3) Task structure and execution process

In the BSC software system, when a task is created, it is identified with a unique ID, which is called the task ID and this task ID is used to recognize this task.

Each task comprises two parts: the first is the "initialization" part, and the second is the "message process" part, as shown in Figure 3-4.

Initialization of task

Message process

Figure 3-4 Task structure

All tasks in the BSC system are structured as shown in the above figure. The shadowed part indicates the special implementation details of a task.


3-7

According to the structure, the execution process of a task can be described as follows (source code is in C language):

{

Initialization( ); /*initialization*/

While(TRUE)

{

Suspended( ); /*suspended, CPU resources not occupied*/

MessageProcess( ); /*executing, CPU resources occupied*/

}

}

After being created, a task first executes the internal initialization and then is suspended for the occurrence of events. When an event occurs, the operating system sets the task as ready and puts it into the executing state for the processing of the event. After the processing is finished, the task is suspended again to wait for the occurrence of next event. This process is repeated in a cyclic way.

Events in the BSC system mainly include message events, timing events and interruption events.

4) Mutual exclusion and synchronization of tasks

In the BSC operating system, some tasks are dispatched simultaneously and executed asynchronously, these tasks are not wholly isolated from one another. Due to such limitation of common resources (e.g. message queue), the operating system must manage the task conditions and restrictions so that the whole system operate in a coordinated way.

In the BSC system, the relation among tasks is of two types: resource mutual exclusion and logic synchronization. The first type means that tasks share some resources while the resources can only be occupied by one task at a moment. Logic synchronization means that there is a certain sequential relation among the tasks and therefore only when a task is executed up to a certain level then other tasks can continue.

In the BSC system, “semaphore” or the “on/off” interruption mode can be used to coordinate the mutual exclusion of tasks. Synchronization is guaranteed with the event driving method. When a task is executed up to a certain level, messages shall be sent to activate the execution of other tasks.

Interruption Service Routines (ISR) mainly include:

Clock interruption, which provides the system with real-time clock and timer services.


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Interruption of communication interfaces to receive frames or other contact signals from interfaces.

Abnormal interruption for the execution of abnormal process in the system. All the ISRs can send messages or sets semaphore to other tasks.

II. Message management

Apart from timing events and interruption events, communication among tasks in the BSC are mainly driven and executed by message events. Each message is used

To activate other tasks into the ready or executing states, and To transfer data between tasks.

1) Description of messages

The message mechanism is to transmit a message of a BM to another task of another BM. Messages can also be transmitted between two tasks in the same BM or even in the same module. The BSC operating system provides application programs with three types of system packets related to message management:

Application packet Transmission packet Release packet

The contents of messages in the BSC can be more deeply understood if combined with the descriptions of flows of the above three types of messages and message bodies. When task T1 applies for message block M and fills in contents, it sends the contents to task T2. This indicates that packet event M is going to occur, i.e. task T2 will move from the suspended state to the ready state. On the other hand, it also means that T1 has sent data (included in the data domain of M, or M data) to T2.

2) Management of message queues

In the BSC, message blocks are managed in the queue mode. There are three types of queues: idle queue, application queue and ready queue. Each queue is enabled in the relation mode, which is shown in Figure 3-5.

Tail pointer of idle queuel

Head pointer of idle queue

Tail pointer of ready queue...

......

......Queue control block

Head pointer of application queue

Head pointer of ready queue

Tail pointer of application queue

Figure 3-5 Message queues


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In the whole system, there is one idle queue and one application queue. For ready queues, however, each task corresponds to a ready queue and ready queues corresponding to one task are organized according to priority levels and the sequence of Send_Message_Block. Messages of the same priority level are handled according to the sequence of the sending time.

To save space and improve efficiency, the BSC provides a common buffer area for all messages. Queue operation only results in the change of queue pointers while the contents of the message block need not to be copied or moved. The process of the change is shown in Figure 3-6.

Idle queue

Applicationqueue

Ready queue of corresponding

tasks

Free message block

Alloc Message block

Send message

Organized according toreceiver ID in the message

Free message block

Figure 3-6 Message queue management

III. Memory management

Memory management is an important content of the operating system, includes memory allocation and recovery, sharing and protection of memory messages, address conversion, and memory expansion.

1) Memory organization

A feature of the BSC is the embedded application, i.e. there will not be frequent memory application/recovery activities. Link mode is used to organize memory blocks and the "Best_Fit" algorithm is used to allocate memory.

2) Memory check and memory protection

The software system of the BSC adopts the plane mode. All data and program codes are stored in a section of memory area. Therefore, memory protection is required to prevent the overriding of memory. In the memory control block there is a "memory block flag" (domain flag), which contains 2 bytes. Two special characters, for example 'M' and


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'Z' are stored to indicate that the memory block is normal (undamaged). If the contents in the flag of the memory control block are not 'M' and 'Z', the contents of the corresponding memory are damaged.

The BSC operating system periodically checks the validity of each memory control block on the memory link, including the check of the contents in the flag to see if they are 'M' and 'Z' or whether contents in the other domains are within the valid range or not. Once a fault is found, the fault recovery mode shall be used for processing. It is also possible that the task containing the damaged memory shall be interrupted and a new task shall be generated.

3) Conversion of memory address

Address conversion is a process of address reallocation. In programming, programmers use logic addresses independent of the equipment. The address space composed is called the logic address space, which corresponds to the physical address of the memory and the physical address space. Once a program written with logic address is stored into memory, and its address and the physical address of the memory set up a relation. To run it correctly, address conversion should be executed according to the relation, that is, to map the program address onto the physical address of the memory.

4) Memory capacity expansion

Memory capacity expansion, also called virtual storage, means that the programmer is not limited in programming by the structure and capacity of a memory that the program can directly access. The system creates a storage space for the user, which is much bigger in capacity than the memory. This requirement-oriented storage space is called the virtual memory or memory expansion. The expansion of memory is implemented in the following two ways:

Division of program address space and memory physical address space. Relocation of program address to physical address, the model is as shown in

Figure 3-7.

a'

Mapping table

aProcessor Memory

Address conversion part

a'

a: program address a': memory address

Figure 3-7 Relocation of program address


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When the memory address of 'a' can not be found via the mapping relation, some information in the program space must be on the external memory. Therefore, the external contents must be first introduced into the memory, and then the address mapping relation is to be modified before the address conversion is continued. The expansion of memory is in fact enabled by occupying CPU time for the switching of internal and external memories and by occupying the external space.

IV. Time limit management

The BSC executes time limit management according to the real-time processing requirements.

Cyclic dispatch: This refers to the clock-level tasks. Clock-level tasks in the BSC operating system are of three types: 10ms cycle tasks, 1s cycle tasks and 1m cycle tasks.

Timeout dispatch: When the time designated by the user is due, timeout messages will be sent to the user to activate the task of timeout processing. Timeout dispatch services provided by the BSC operating system include absolute time limit and relative time limit. Absolute time limit requires the operating system to process tasks at an absolute moment defined beforehand. Timeout messages will be transmitted at this absolute moment. The absolute time has two cases:

Without cyclic repetition: The system is required to monitor a future moment. When the task is over at due time, the procedure will be ended, i.e., it will not be repeated again.

With cyclic repetition: A user can set certain time after which a function/procedure can be repeated so that regular results can be obtained.

For example in call charging there is need for call bills (call data). A process can be set on 02:00 with the cycle of 24 hours so after every 24 hours the call bill process will start at 02:00 and will provide the required data.

Relative time limit means that timeout processing shall be executed some time after the user puts forward the timeout requirement.

The BSC operating system provides the following system invocations related to timer services:

start_devtimer: start relative time limit services with the basic unit as second.

start_100ms_devtimer: start relative time limit services with the basic unit as 100ms.

stop_devtimer: stop relative time limit services.

register_sys_timer: register unrepeatable absolute time limit services.

register_day_timer: register repeatable absolute time limit services with the cycle of 24 hours.


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cancel_sys_timer: cancel absolute time limit services.

V. Initialization and system recovery

To improve the system reliability and self-recovery, the BSC system provides two important system recovery levels: restart and booting loading.

Restart mainly executes initialization operations and then decides whether to start booting loading according to the restart level. In this way the control and state variables of the system can be recovered as defined initially.

Booting loading is the recovery of a higher level. Programs and data will be reconfigured in the memory through OMC.

1) Restart

The BSC system provides four levels of restart in accordance to different operational environments and terminal maintenance facilities. Detailed functions and system restart effects are given below.

Restart of Level-1:

Ongoing call proceeding will be affected. Connected calls will not be affected. Data and programs will not be loaded.

Restart of Level-2:

Control and state variables of all modules are initialized.

Ongoing call proceeding will be affected. Connected calls will be affected. Data and programs will not be loaded

Restart of Level-3: Reinitialize the whole system. Data is loaded through BAM/OMC. No program is to be loaded.

Restart of Level-4: Reinitialize the whole system. Both data and programs are loaded through BAM/OMC.

2) Booting and loading

The system booting program and the system loading program of the BSC are 64 Kbytes in total. The basic input and output system (BIOS) occupies 512 bytes, and the rest is the loading program.

After powered on, the system first enters ROM BIOS and executes the initialization of GMPU memory, clock and interruption.

After this, the system will start the loading program.

The loading process is as follows:


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Initialization of the global address table, interruption descriptor table and partial descriptor table to enter the protection mode.

Initialization of timer interruption mode. Reading the setting of hardware switches to decide whether reload from the BAM

or from the Flash Memory. To load from the BAM, either data only, or program only, or both data and program can be loaded. The parts that are not loaded from the BAM are loaded from the Flash Memory. The sizes of program and data Flash memories can be set by jumper setting to meet different operational requirements. When re-loading from the Flash Memory, the loading program shall check the programs and data in the Flash Memory. If errors are found, the loading program will request to load from the BAM.

Selection of the loading path. Different loading paths shall be used for different configuration requirements of modules.

If program or data is to be loaded from the BAM, set up connection with BAM. Otherwise omit this step.

Load the GMPU program or data to the designated directories. Check after loading. If the loading is not correct, re-load the data or program. If the program is loaded correctly, read the switch state of the hardware to decide

whether to back up once again the program that has been loaded into Flash Memory.

Switch to GMPU software program execution. The dumping of the GMPU data to the Flash Memory is done by the GMPU. The loading program is responsible for the verification task only.

3.3.2 Database Management System (DBMS)

Functions of the BSC are executed by program control while the introduction and deletion of these functions are enabled in a coordinated manner by data in the BSC. In general, the data is stored and managed in a centralized mode, and the collection of the data is called database. The management of database is executed by the DBMS module in the GMPU software of the BSC.

I. Data structure

According to its organization, the DBMS can be classified into hierarchical, meshed and relational databases. According to the data storage mode, DBMS can be classified into distributed and centralized databases.

Data in the BSC is distributed in multiple modules, but logically belongs to the same database. For single-module BSC, module number is 1 and all data of DBMS are distributed in a single module. The relation of data is described in a bivariate table, which is called relational table. One dimension of the table is called tuple, and the other is called domain or field. Tuple composes one logic record, while domain defines the


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relevant data item of the relational table. The number of domains reflects the complexity of relational table.

1) Data dictionary

Data definitions in DBMS are described by the data dictionary. Two types of description tables, relational description tables and domain description tables, are generated. The former type describes the structures of relational tables and the latter describes the domains in tables.

2) Data type

Data used in the database of BSC is basically of the following types:

Unsigned character integers within the range of 0 ~ 255. Unsigned integer within the range of 0 ~ 65535. Unsigned long integer within the range of 0 ~ 4294967295. BCD character string, the valid values of characters are within 0 ~ 9. ASCII character string, valid ASCII characters.

3) Table types and retrieval methods

Descriptions of table types are in the relation description table of the data dictionary. Database of BSC uses the following three types of relational tables.

Direct index table: The tables are directly accessed by using tuple numbers. The tuple number is not a part of the relation, and the insertion and deletion of the tuple shall not affect the sorting of the table.

Sequential search table: All tuples in the table are stored according to the sequence. The search starts from the first tuple and continues in sequence. The newly added tuples are put at the end of the table.

Sorting table: Tuples in the relation are sorted according to values of key words. Two tuples can not be stored in one table if values in their sorting fields (key domain) are the same. In case there are multiple key domains, each key domain can be assigned with the sorting mode (ascending sequence or descending sequence) and sorting serial number. The domain with the smallest serial number is in the first priority. The retrieval of the sequencing table is enabled through dichotomy. The insertion and deletion of a tuple will cause the movement of the subsequent tuples.

II. Database structure

The database of the BSC has the distributed structure. Data is distributed in multiple modules. Each module is responsible for maintaining the local database on the module and hence is relatively independent. At the same time, each local database is a part of the global database. Multiple local databases cooperate together to provide the functions of the global database.


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The structure of the database on each module is shown in Figure 3-8. Note that there is only one BM in single-module BSC, hence AM/CM is not required.

AM/CMBSC database

API API

DBMS

Application programinterface

DB

DBMS DBMS

Database Database

BM BM

DBDB

Figure 3-8 Module database structure

1) Database

A database, composed of multiple relational tables, is loaded into the memory of GMPU through BAM from OMC. The access of DBMS to the database is made in RAM and no disk file operations are needed, hence high speed retrieving is achieved.

Via the control of the GMPU DIP switches, data can be stored in the Flash Memory, and the modification of data can be duplicated onto the Flash Memory of GMPU, which will not be lost in case of power failure. On system restart, GMPU can read the originally stored data from Flash Memory and store it to the memory of GMPU, so it is not necessary to load it again.

2) Functions of database management system (DBMS)

Functions of the DBMS in the BSC include:

Data definition (defining the structures of relations, field types, distribution places of data, access modes, etc.)

Provision of application programs with interfaces for retrieving, storing and modifying data.

Ensuring the consistency and safety of data. Data backup.

3) Application Program Interface (API)

The API of the database is the interface between the database module of the BSC and other modules. It makes use of functions provided by the DBMS and provides database access interfaces for such modules as radio resources management, base station management, operation and maintenance, performance management, alarm management and BAM.


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Functions of API are given below:

Radio resource data management provides data configuration of the following functions: call procedure, system information, channel management, power control, handover decision, short message, timer management, frequency hopping (FH) management and flow control.

The BTS data management provides the BTS configuration data for the base station management module.

SS7 signaling data management provides the configuration & management of MTP and SCCP.

Circuit data management executes management of A-interface and Abis interface circuits according to the configuration of circuit data so as to guarantee that the assigned circuits in the call process are configured and valid.

Data support for operations and maintenance provides hardware configuration data for the operation and maintenance module.

Data support for alarms provides alarm configuration data to alarm modules. Data maintenance, cooperates with BAM to enable maintenance of the database,

including the storage, dumping of the database and the addition, deletion and modification of tuples in the relational table.

III. Features of BSC database

1) Distributed database

Data is distributed in multiple modules. Each module stores its own data. All data requests are sent to the local database, and the user does not need to care about the storage places of the data. Due to this distribution of data, a fault within a module will not affect the working of other modules. As for single-module BSC, all data is stored in a single module. All queries are done locally, this helps to improve query efficiency.

2) Flexible and reliable expansion

The structure of the relational table and definitions of fields are wholly based on descriptions of the data dictionary. Modification of the table structure or the introduction of relations will not cause the change of program code. Therefore, DBMS features fine expandability.

3) Flexible data setting

BSC must satisfy multiple networking modes and requirements for multiple services. Its flexible designing makes it free from restrictions.

3.3.3 Software and Data Maintenance

I. System software and data protection

The system software and data of the BSC are stored as files in multiple storage media. The BAM in the BSC has two 1GB hard disks mirrored to each other, carrying the


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software and data of BSC. The software and data can also be duplicated on optical disks or tapes for backup.

GMPU board on each BM of the BSC has one 4MB (for program) and one 3.5MB (for data) Flash Memories. Also, It has 32MB RAM, in which the program and data in actual operations are stored. The intelligent boards also have flash memories of different capacities to store the software and static data of local modules or boards. Flash Memory provides such functions as power-failure protection, high access speed, and repeated erasing and writing. The relation of the BAM hard disk, Flash Memory and the software and data of memory is as follows.

The hard disk of BAM has a loading description file, which describes the file names and directories to be loaded on different modules and intelligent boards of different types. When there is a request for loading from GMPU or intelligent boards, BAM shall send the needed software and data to assigned GMPU or boards via corresponding loading channels according to the descriptions in the loading description file. At the same time, BAM shall decide whether to write the software and data to be loaded into the corresponding Flash Memory according to the loading switches on GMPU and boards (program available, program writable, data available, data writable, etc.). According to the GMPU or board switch settings, when the system or boards restart, either the software and data from the Flash Memory should be used or software and data shall be loaded from the hard disk of BAM. Data modified dynamically in the memory (such as the online settings of data in some tables made by the maintenance staff) shall be written periodically into the Flash Memory and the hard disk of BAM so as to ensure that the modified data is valid during system restart.

Each module has two GMPU boards in active & standby configuration. These boards are mutually updated through GEMA to ensure the smooth transition of system during dual-system switchover without any disturbance to the subscriber services.

In general, the system software is a kind of data itself, which is recorded, stored and used in the form of file for the purpose of centralized management. So the management of software and data is just management of data in the final analysis.

II. Data and database

1) Data

Service and functions of the BSC are implemented by programs, and the description, import, addition, deletion and control of the application range and environment are enabled by specific data. Programs and data are separate. Programs respond to events according to the settings of data and implement the services and functions of the BSC. With data driving, system flexibility has been enhanced and the planning, optimization and adjustment of the system is facilitated by making data modifications.


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In the traditional file system, each program defines its data files, "redundancy" and "inconsistency" are always caused. "Redundancy" is caused as the same data is used by different programs and, it is dumped for many times. "Inconsistency" always occurs when a program modifies its own data files while not modifying the same data obtained in the data files of other programs. As most data must be used and owned by multiple software modules, the issue of data sharing must be solved.

Various data are usually stored in a centralized way. And the set of the data is called database, which is managed by DBMS. If the user needs some data, he or she can make request to DBMS, which will provide the user with the data needed.

To make full use of the system structure of BSC, which is the multi-module distributed group control structure, Distributed Relational Database Management System (DRDBMS) can be used to organize, manage, describe and access the data of BSC.

In addition, another advantage of adopting DBMS is the safety, i.e. the protected data can not be accessed or modified by unauthorized users and can not be damaged by disastrous events.

The database in the BSC is described in the distributed relational data mode. It is distributed because each BM stores part of the data, including global data, global link table data and private data. Data on one module is stored according to the relation mode and is managed by the relation database sub-system in a unified mode. Relation database sub-systems on different modules are independent of and consistent with one another. Therefore, the relation database sub-systems of switching modules are physically separated and compose a part of the whole database system. Logically these relation database sub-systems are an organic integrity and compose the distributed relational DBMS.

In the relational database of the BSC, the data is made up by two-dimensional tables, which are called relational tables and are a set of relative data, as shown in Figure 3-9.

} Tuple

Key domain

Figure 3-9 An example of relation

A row in the relation is called a tuple (or record) and a column is called a domain (field). Each tuple constitutes a logic record. For example, in a relation that describes equipment, the amount of tuples is determined by the amount of equipment, and the


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amount of domains is decided by the degree of complexity of the logic. The use of this relation facilitates programming and application

Data in the relations of BSC includes unsigned integers with 1 - 4 bytes, BCD codes, tuple numbers of 2 bytes and block types with uncertain bytes.

Data in BSC is of the following types:

System data: Intrinsic data of the software, such as software parameters, timer and event descriptions.

Configuration data: Data of the BSC cabinet, frame configuration, slot configuration, mailbox, transmission HW configuration, clock configuration, etc.

Local office data: This data describes the network parameters of the local BSC and represents some information such as signaling point information of BSC, phases of the interfaces, mobile country code, mobile network number, basic data for subordinate cells, configuration data for carrier frequency, TRAU configuration data, radio channel configuration data, BIE configuration data for BSC side and site side, LAPD configuration data, signaling channel configuration data, traffic channel configuration data, etc.

Site data: It describes the configuration data of subordinate sites of the BSC, including site slot position data, board software configuration data, configuration data for frequency points of the cell carrier frequency.

Cell data: It describes the properties (data) of the subordinate cells of the BSC, including system information data of the cell, cell frequency allocation data, frequency points of adjacent cells, switches and parameter data for intra-cell call control, other properties of the cell, etc.

Handover data: It describes the parameter and switching data required for handover control.

Power control data: It includes parameters and switching data needed by the BSC in power control, including power control selection data, cell power control data, the BTS power control data and MS power control data.

Channel management data: It describes data required by BSC during the management and allocation of radio channels, including radio channel management and control data and bad channel management and control data.

Trunk data: It describes circuit data of A-interface and Pb-interface, and data of their signaling coordination as well as Abis-interface circuit data.

SS7 data: It describes data of MTP and SCCP of SS7.

Alarm data: It describes the alarm parameter data of BSC and BTS.

2) Database


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The BSC organizes data by using the relation mode, which describes the relation between entity set properties and entity sets via the two-dimensional tables that enable relational algebraic operations. The relation mode induces the logic structure of data to a two-dimensional table that satisfies certain conditions, and the table is called a "Relational Table". The major characteristic of relational table is that not only data, but also the relation between data is represented.

The BSC database is a set of data relations, made up by various two-dimensional tables. One dimension is called tuple (row), and the other is called domain (column). Each tuple is equivalent to a logic record, and each domain corresponds to a certain property and is equivalent to a data item in logic records. Hence the amount of domains is determined by the logic complexity of the relation. In a relational table, key domain instead of pointer is used to query data. And a key domain can include one or multiple domains. Each search domain also includes one or several domains and is used to store a certain tuple in the record.

To obtain the data of some tuples, a user program must inform DBMS of the relational table and also the tuple in the table to be stored. This can be done by defining the search domain.

In the database of BSC, relations are of two types:

Real relation Virtual relation

Real relations refer to the relations that are defined by software, stored in the database and found in the GMPU memory.

Virtual relations, on the other hand, are not stored in the database and memory, but created by reconstructing the real relation so as to speed up the search for data and meet different requirements of users. Virtual relations mainly include redefined relation, multi-target relation and procedure relation.

A redefined relation is actually a sub-set of the real relation. That is, the existing real relation is re-defined. Some domains in the real relation are extracted and the sub-sets are given a redefined relation, as shown in Figure 3-10.

Name and address Personal file

(Redefined relation) (Real relation)

Cell name Cell number Cell name Cell number Cell type Cell CGI ...

A 0 A 0 GSM900 4600027000001 ...

Figure 3-10 Example of a redefined relation with same key domains

It can be seen from Figure 3-10 that the name and address list is actually created by reconstructing two domains extracted from the personal file list. Therefore this list is not


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stored in the memory and database. For a redefined relation, the key domain should be the same as that in the real relation. In the operations of BSC, if a user (or the software that uses data) needs to use the data of a tuple in the redefined relation. A request should be put forward to DBMS, which will extract the domains related with program operations from the relative real relation and construct them into a newly defined tuple to send to the software requesting. The structure of the redefined relation, obviously, is not same as that of the real relation it is based on. And no modification is allowed on the redefined relation.

Multitarget means that it is composed by domains extracted from at least 2 real relations by using the designated link algorithm, as shown in Figure 3-11.

Name and ID table (real relation) ID and address (real relation)

Cell name Cell number Cell number Cell CGI

A 0 0 4600027000001 Key domain |________________________| key domain

Link domain Name and address list (virtual relation)

Cell name Cell CGI A 4600027000001

Key domain Key domain

Figure 3-11 Example of a multi-target relation

It can be seen in Figure 3-11 that in constructing the "Name and address list" of the multi-target relation, one of the two real relations shall provide the base point for constructing the virtual relation. Therefore, the key domain in the multi-target relation should be the key domain of the real relation. In addition, the link domain plays a vital role in constructing the multi-target relation, because the data in the next real relation can only be found by using the link domain. Hence the value of the link key domain in the first real relation should be the same as that in the key domain of the second real relation in the multi-target relation. This induction shall go on until all domains involved in multi-target relations are completely linked.

The application program of the BSC does not care whether a multi-target relation exists in the memory, but it cares how to obtain the required data in program operations quickly and conveniently from the multi-target relation.

The procedure relation is a type of virtual relation. It is reconstructed by one or multiple real relations. A procedure relation is a section of small program (called "procedure") that dispatches the data in the corresponding real relationship according to the process for specific functions execution and follow a certain sequence or algorithm. In the procedure relation, some domains are dispatching entrance parameters. Some other domains use algorithm to execute the calculation results or output parameters. If the


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procedure relation can not find the real relation needed from the local GMPU memory, the real relation will either in the memory of other modules or stored in the system disk.

The BSC system adopts the modular distributed control technique. Each module is equipped with data according to the required functions. Hence the database of the BSC system is actually a sum of the data in all modules. Its physical arrangement in the database must be determined by actual needs. For single-module BSC, there is no distribution of data in multiple modules.

A common relation can be found in a certain module, and its tuples are not distributed in other modules. In some cases, a module needs only part of the data in a relation while other modules shall need the other data of the relation. To avoid repetition, the relation can be divided into different blocks. Each block shall only store the tuples for access. In this case, a relation is thereby distributed into different modules.

Another case is that a group of modules need the same data of a same relation. If there is only one relation for such data, it will take a long time to access the relation as all data requests will be sent to the module that contains the relation. To avoid such an event, data copies of the relation should be kept in all modules that shall use the relation. That is, the relation shall be copied into different modules. For the repeated use of a relation, the key point is to keep the data copies consistent with one another.

In a word, a module can contain an independent data relation or related data relations, that is, distributed relation and replicated relation.

1

2

3

4

5

DBMS

Module 1

6

7

8

9

10

DBMS

11

12

13

14

15

DBMS

Module 2 Module 3

Relation A Relation A

Relation BRelation BRelation B

Relation AUser

software

Figure 3-12 A distributed relation

It can be seen from Figure 3-12 that the data distributed into three modules belong to the same relation A, whose 15 tuples are distributed to different modules. Module 1 contains tuples 1-5 of the relation, module 2 contains tuples 6-10 of the relation, and module 3 contains tuples 11-15 of the relation. If the user software of module 1 needs to access the data in tuples 1-5, it can find the data in the local module.


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1

2

3

4

5

DBMS

Module 1

1

2

3

4

5

DBMS

1

2

3

4

5

DBMS

Relation A Relation A Relation A

Relation B Relation B Relation B

Usersoftware

Module 2 Module 3

Figure 3-13 A replicated relation

It can be seen from Figure 3-13 that data in the three modules of relation B is the same and contains all tuples (1-5) of the relation. In the event that a module needs the data of the relation, it need not search in other modules. But when the data in the relation is to be modified, data in all these three modules must be modified. It can be retrieved from the data dictionary as for which modules contain copies of the replicated relation.

Some relations in the database of the BSC can either be separated or replicated, or both.

The database system of BSC can be divided into two layers. The bottom layer is the relation management layer used to provide such functions as:

Storage, query, modification and duplication of expansion relation-based data modes.

Control of the integrity, processing-based safety and consistency of data. Backup of database.

The upper layer comprises service level interface modules and the data maintenance modules. Service level interface modules support the query and search of database in service modules. And the data maintenance and the terminal data management console enables the modification and query of online data as well as other maintenance management operations in the database.

There are three ways of retrievals in the of BSC database, which can be found by checking the data dictionary.

Sequential retrieval: All tuples are stored according to the sequence. And each access shall start from the first tuple, then goes on with the second until the needed tuple is found. The newly added tuple is put at the end of the relational table and the constantly read tuples are put at the beginning.

Index access: This means the access to a relational table via the index domain of an index list. Index access is applicable to direct index lists. The index domain is


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implicated and not a part of the tuple to be accessed. In general, the values of the key domain compose the index according to the sequence. If the contents for index are too many, they can be divided into blocks and set into the indices of multiple levels.

Dichotomy retrieval: The dichotomy retrieval starts from the middle of the relational table. If the value of the limited condition (composed by multiple key domains) is greater than that of the entered value, it will compare with the mean value at the bottom half (key domains are arranged from small to big into the dictionary sequence), and continue the binary comparisons until the required tuple is founded.

Dichotomy is a quick search algorithm. Its shortcoming is that the addition or deletion of a tuple is very complicated by reorganizing and rearranging the relation.

III. Data maintenance and operation terminal system

The data maintenance and operation terminal system follows the client/server structure. The data management server is an object-oriented server set up on the description-based database system. It not only enables the data access request of the client terminal, but also provides data storage and access capability for other application sub-systems. The client terminal of data management provides a convenient and friendly man-machine interface and provides functions for the BSC as addition, deletion and modification of both single-piece and batch data as well as sequencing, querying, setting, printing and backup of data. To ensure the safety of data, three levels of operation authorities are set for operational staff which are operation authority, setting authority and management authority. The operation authority has the lowest level, setting authority has higher level and management authority has the highest level of authority.

1) Data management

The distributions of data arise from requirements of specific application systems. For large-scale database management systems, distributed management can improve system performance and reliability and reduce system costs. For BSC, the introduction of the distribution concept increases the flexibility in system configuration and curtails cost.

The configuration structure of the single-module BSC is shown in Figure 3-14.


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BM

BAM

Client Client

Database

DatabaseForeground

Background

M900/M1800 BSC

Figure 3-14 Structure of a single-module BSC

The configuration structure of a multi-module BSC is shown in Figure 3-15.

BM

BAM

Client Client

Database

Database

Foreground

Background

AM/CM Database

BM Database

M900/M1800 BSC

Figure 3-15 Structure of a multi-module BSC

Data is first distributed on the BAM server. Then it is sent to and stored in the BM and the database of AM/CM after conversion and loading. BMs and AM/CM only need to access the data in the local module when reading data instead of paying remote access via inter-module links, which improves the system performance. Data of each BM is


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different from that of AM/CM. Only related data of each module is stored in it so that distributed data management is realized.

The BSC can be configured with multiple terminal systems. Each maintenance system can maintain the data of the BSC. Via the management of user authorities, illegal access or operations can be controlled.

2) Data conversion

According to the features of data operations, the foreground database adopts the self-designed special database system, whose data management mode based on the specific characteristics of the BSC, is different from normal database systems in storage format, relation mode and index mode. The database of the background maintenance terminal system adopts the standard database mode to enable the storage format, relation mode and index mode. Hence the difference between the data formats of the background and the foreground comes into being. The background maintenance terminal system adopts the format conversion mode to keep the consistency of foreground and background data as well as validity of data. The conversion process converts the data required by different modules into different files according to the configurations of modules. In the loading process, relative data files shall then be loaded into relative modules.

3) Data management server in the client/server structure

The client/server structure is a very popular database management system. DBMS is designed on the bases of ORACLE and SYBASE. The advantage of the structure is that according to the division of functions, data operations and data usage are separated. Functions are shared and the performance of the system is greatly improved. The security of the database system is further guaranteed and provides multiple and flexible operation methods and modes for large-scale data applications.

The service access mechanism under the client/server structure is shown in Figure 3-16.


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Message processing

Background message processingDa

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Figure 3-16 Service access mechanism

4) Contents of data maintenance

Data management of the BSC includes configuration data management, local office data management, site data management, cell data management, handover data management, transmitted power data management, channel data management, trunk data management, SS7 data management, alarm data management and data operation management.

Configuration data management: Configuration data describes the hardware configuration of the BSC, common parameters and data in the AM. Hardware configuration includes frame description, slot description, board description, NOD description and module description. Common parameters include module parameter, maximum common tuple number and semi-permanent connections. AM data includes AM frame description, AM board position description, AM board active/standby group, AM module description, AM clock description and AM alarm switch description.

Local office data management: Local office data includes local office parameter data, mobile country code table, mobile network number conversion table, BSC cell table, frequency hopping data table, TRX configuration table, radio channel configuration table, LAPD semi-permanent connection table, LAPD signaling connection table, TRAU configuration table, BSC BIE board description table, the BSC BIE board active/standby group description table, the site BIE trunk mode description table, the site BIE configuration table, signaling channel connection table, SS7 timeslot table, the corresponding relation between MSM and FTC, GMEM board configuration table.

Site data management: Site data includes site description table, TRX configuration table, frame description table, slot description table, software configuration description table, BS environment alarm configuration data table and TRX handover control table.


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Cell data management: Cell data mainly includes system information data, cell configuration data, cell frequency point data, BCCH data of adjacent cell, SACCH data of adjacent cell, cell attributes data, cell alarm threshold data, cell call control data, and cell call handling parameter data.

Handover data management: Handover data includes handover control data, cell description data for handover, external cell description data, cell adjacent relation data, filter data, penalty data, emergency handover data, load handover data, normal handover data, fast-moving handover data and intra-cell handover control data.

Power control data management: Power control data mainly includes power control selection data, ordinary cell power control data, BTS power control data, MS power control data, and HWII power control data.

Channel data management: Channel data mainly includes radio channel management control data and damaged channel management control data.

Trunk data management: Trunk data includes office direction data, trunk group data, trunk group SS7 data, A-interface trunk circuit data, and Pb interface trunk circuit data.

SS7 data management: The BSC supports SS7 mode which is 14/24-digit compatible. The 14-digit mode is used in BSC. SS7 data management includes the management of DPC data, SS7 link set data, SS7 route data, SS7 link data, CIC data, PCIC data, SCCP destination signaling point data, SCCP sub-system data, GT code conversion data and new GT code conversion data.

Alarm data management: Alarm data mainly includes such data in the BSC and BTS as alarm parameter configuration data, alarm environment variable configuration data, alarm information parameter data and alarm information detailed explanation data.

Miscellaneous: In addition to the above-described data, there are still many system parameter data such as software parameters and clock parameters.

3.3.4 Radio Resource Management

A critical difference between PLMN and PSTN lies in their resource management. For PSTN, communication medium can be applied to use whenever a call needs to be established. While for wireless cellular system like GSM, the dedicated channels of the radio interface is allocated to the MS (a requirement of the network). When MS drops the call the radio channels will be released and wait for another call request.

Specifications of the GSM signaling part comprise three functional parts, which are Radio Resource Management (RR), Mobility Management (MM) and Communication Management (CM).


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The key contents of radio resources management is to manage the transmission route of the radio interface, and responsible for the establishment, maintaining and release of radio resources.

RR connection is used to connect two peer entities and provide support to the exchange of information in the upper level, and as a result, point to point conversation between MS and network can be implemented. Additionally, RR management is responsible for receiving information from BCCH (PBCCH) and CCCH (PCCCH) channels.

Radio resources management is distributed in four entities in the GSM system architecture, which are MS, BTS, BSC and MSC. MS and BSC are responsible for most of the work.

Mobility management is responsible for the MS location/route data and its updating. This function is mainly accomplished by MSC (SGSN).

Connection management is responsible for controlling the interworking between the GSM network and other networks and for the setup and release of the end-end transmission path to support communications between users. Connection management depends on the functions for handling the user's mobility and security in mobility management

I. Call procedure

During the radio channel management, various messages are exchanged between different equipment of the network and MS.

The BSC accomplishes signaling processing of various interfaces in a call process and consequently implements radio resources management.

The whole call process starts from access. Access can be triggered either by MS (e.g. MS activation request or location update information), or by network (e.g. paging for GSM subscribers). The access of mobile station is made through the random access channel (RACH) or packet random access channel (PRACH). In MS access request only an information of 8 bits is provided, which can not give the specific identification of the MS. This may result in mistaken access requests due to frequent interference. In addition, RACH (PRACH) transmission is irregular. It is possible when two mobile stations initiate request for access at the same time, it will result in the failure. In the BSC system, the threshold values can be set for BTS to effectively prevent mistaken reports and to distinguish random access collisions.

GSM phase2+ supports two kind of services i.e. data services and speech service. The procedure of circuit and packet calls are described below.

1) Circuit-based call


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In this procedure, BSC initiated a dedicated channel allocation procedure after receiving an access request from MS. The BTS decodes the request correctly and indicates the BSC to allocate a dedicated channel and activates it in BTS via channel request information. Then the BTS informs the MS to accept the dedicated channel via AGCH (access grant channel).

In special cases, if the network facilities response so late to the access request that the MS re-sends access request, multiple channels may be activated in the BTS. Only one will be used effectively (the information carried on the 8-bit access requests is not sufficient for distinguishing mobile stations), as a result, the limited radio resources will be seriously wasted. In the BSC, a mechanism is designed to prevent such cases. Thanks to this mechanism, dedicated channels can be established quickly even in big traffic situation, which consequently accelerates the process of signaling connection and shortens the signaling connection time.

In the specially established channel, signaling interaction is executed between the mobile station and the network facilities. After the interaction, the network obtain the necessary information and allocates a terrestrial link for calls from the MS. Then it informs MS via radio interface to access and begin the communication process.

Channel release procedure begins after the communication is finished, where radio links and terrestrial links will be released successively.

2) Packet-based call

When no PCCCH is configured in the serving cell, the channel request message from the MS is transferred to the BTS via RACH and then reported to the BSC. The BSC forwards this message to PCU and receives the packet immediate assignment message from PCU and then sends it to the MS. The BSC will not handle the packet channel request, but sends it directly to the PCU.

If an MS accesses the packet services for Paging Response, the BSC can not determine the service type of the access, it then allocates DCCHs first and enters dedicated mode. After EST_IND of RR_INITIALITION_REQ of layer 3 is received, it transfers the message to PCU and then enters packet call.

If the MS access packet service via the PCCCH of the cell, then the packet call procedure is transparent to the BSC.

II. System information

System information are information about network technical attributes broadcast incessantly in the BCCH (broadcast control channel) and SACCH (slow associated control channel). It includes frequency configuration of cells, configuration of common channels, whether or not to allow emergency calls, whether or not to allow call re-establishment, etc.


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MS in idle mode constantly receives system information to keep contact with the network facilities. In addition, many parameters in system information control the activities of the MS, including by what means the MS selects cells, by what means the MS starts access applications, whether the MS adopts the VAD transmission technology, etc.

At present, M900/M1800 BSC system provides 12 types of system information demanded in GSM Phase 2+. The system can support the coding of 1024 frequency channels and the free usage of dual-band mobile stations in the networks of GSM 900 and GSM 1800. In the coding of frequency channels, the limited resource of system can be most effectively used by selecting automatic coding formats according to the range of the input frequency channel. Frequency point coding formats currently supported by the system are Bit map 0 format, Range 1024 format, Range 512 format, Range 256 format, Range 128 format, and Variable bit map format. Besides, frequency point coding of the above formats are also enabled in the descriptions of adjacent cells in system information, and as a result, the handover of dual-band mobile stations between GSM 900 and GSM 1800 networks can be implemented.

In system information, some data shall be defined by service provider. The BSC system provides friendly interfaces, which makes information upgrading easy.

In addition, system information in the BSC system also supports GSM 1800 Class-3 MS, and provides necessary parameters for GSM 1800 Class-3 MS to enable the functions of power control, handover and cell selection.

The 12 system information supported by the BSC system includes SI1/2/2bis/2ter/3/4/7/13 and SI5/5bis/5ter/6. 5/5bis/5ter/6 are transmitted on the SACCH and the other 8 messages are transmitted on the BCCH. Only in case of packet service support, will the cell transmit the system information 13 (SI13). Whether the transmission of 2bis/2ter/5bis/5ter is permitted is up to the BCCH frequency point configuration of its adjacent cell. For detail information, please consult GSM 04.08 protocol. The PCU is responsible for the packet system information transmitted on the PBCCH.

III. Channel management

Channel management includes two aspects. The channel set for each cell must be determined, and certain equipment should be configured. This is a "long-term" cell channel configuration management. On the other hand, channels shall be allocated/released periodically according to the communication requirements of MS. This "short-term" management is called the dedicated channel allocation management. Channel configuration management and channel allocation are all handled by the BSC. The MSC only indicates the types of channels for each specified communication while the BTS executes relevant tasks controlled by BSC. Both types of management


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activities have great effects on the signaling handling processes on radio and Abis interfaces.

The BSC is not responsible for the allocation of the PDCH (packet data channel), it only records the state of the packet data channel. When there is change to the state of the PDCH at the BSC side, the BSC needs to notify the latest state of the PDCH of the PCU.

IV. Channel configuration

Channel management in the BSC system provides friendly user operation interfaces for the channel configuration management of cells. Data of broadcast channels, dedicated channels, traffic channels and radio frequency points can be conveniently configured and modified.

1) Allocation of dedicated channels

Dedicated channel allocation management of the BSC system follows the combined strategies of VEA (very early allocation) and EA (early allocation). The VEA strategy is used for some special calls while EA is for ordinary calls. The combined modes can effectively improve the usage of channels. Besides, if the local cell has no idle channel to assign, the system will initiate the directed retry mechanism, and requests radio channels from its adjacent cells to establish that call so the success ratio of calls is improved.

Channel management in BSC system divides the idle channels into different groups according to interference conditions and traffic is allocated accordingly.

The packet channel resources ensure the reasonable load-sharing between channels, based on a specially designed algorithm of Huawei. In addition, channel management in the BSC system supports the allocation of access applications of different priorities and the queuing of access applications.

The allocation of dedicated channels can be executed according to the preset priority levels. In some cases, access requests of higher priority can forcibly occupy the channels being used by lower priority users. When the channels are busy, access requests can be queued. Under the protection of the preset timer, dedicated channels can be allocated for new access requests within a period acceptable to the users.

2) Dynamic allocation of SDCCH

In many cases it is difficult to predict and calculate the demand of a cell for SDCCH. The SDCCH dynamic allocation mechanism employed by BSC system enables the channel configuration to be consistent with the current actual traffic model (features) so as to reduce call loss and maximize the system capacity.

Its key idea is, if SDCCHs are insufficient in a certain cell, TCHs will act as SDCCHs; if SDCCHs become idle later, the TCHs will be restored.


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3) Timeslot frequency hopping

The BSC supports frequency hopping at timeslot level of the radio channel. The frequency hopping parameters of all the timeslots are configured and maintained at the GMPU of the BSC, including MAIO, HSN, TSC, and MA table.

Frequency hopping parameters of different timeslots can vary when they meet certain restrictions, that is to say, timeslot hopping parameters are of diversity.

During the procedures of BTS initialization, BTS configuration under normal running state, cell call and handover, BSC will control frequency hopping by sending the channel frequency hopping parameters contained in the message to the BTS according to relevant protocols.

Frequency hopping can be divided into radio frequency hopping and baseband frequency hopping. Frequency hopping improves usage efficiency of radio frequencies and enhances the anti-interference capability of the radio channel, which is of great importance in cell planning.

4) Issuing configurations to the PCU

To ensure the consistency between the BSC data and PCU data, the data shared by the two entities is configured from the data management console at the BSC side. The configurations are issued to PCU via the BSC during the process of running.

These data mainly include two parts: cell attributes and channel attributes. Cell attributes include cell state, CA list, cell features and attributes, which are closely related to the system information. Channel attributes include channel state and frequency hopping attributes, etc. And the BSC issues configuration with the cell as the unit.

The processes of configuration issuing between the cells can happen in parallel, but the processes inside the cell is in series.

5) Dynamic PDCH control

It is difficult to predict the packet traffic of the cell. To improve the usage of channels, dynamic PDCH is introduced. Dynamic PDCH is initialized as a TCH and controlled by BSC. When the static PDCHs are not sufficient, the PCU will apply for dynamic PDCHs from the BSC. When the PCU is granted with the control authority, dynamic PDCHs are used for packet service. On the contrary, if TCHs are insufficient, the BSC can request dynamic PDCHs from the PCU. When the BSC is in control, the dynamic PDCHs serve as TCHs. It is not the BSC but the PCU that is responsible for packet data channel allocation.

V. Short Message

Short message service does not require an end-to-end path. The short message communication is limited to one message only. In other words, the transmission of one


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message makes one communication. The short message service is transmitted transparently to BSC.

VI. Timer Management

There are different timers, which play important roles during the whole call procedure. These timers control the progress of the calling. Beyond that, the sampling of some timers will affect the performace of the equipment of different manufacturers in time of inter-connection. The timers in the BSC software system operate in dynamic management mode. When calls are made, the timers almost take up no processing time of the main processing unit in the course of processing so that the GMPU of the BSC software can handle more calls. Besides, the timers in the BSC system adopts a flexible management mode. The equipment of varying manufacturers can be interconnected easily and effectively by setting the call timers dynamically from the OMC data management console and resorting to the testing tools available in the BSC system. This creates a huge free space for service providers.

3.3.5 Handover Decision & Power Control

The MS may keep on moving during communication, which causes a continuos change in its relative location. To ensure the channel quality during communication, the MS incessantly measures the quality of the radio channels of its surrounding cells, and reports the measurement results (MR) to the BSC via the BTS in the serving cell. The BSC performs radio link control according to such messages as level intensity and quality level of the serving cell and its adjacent cells contained in the MR, to guarantee the channel quality during the whole communications process. When the MS moves from one cell to another, then for better voice quality, MS should be connected to the new cell.

To meet the increasing requirement for capacity and functionality in the GSM system, the BSC improved its GMPU capability by introducing the idea of distributed processing, that is, MR preprocessing, handover decision, and power control functions are distributed in GLAP boards and BTS system.

The structure of handover decision and power control in the BSC system are shown in Figure 3-17.


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GMPUOMC

LAPD

LAPD bottom-layer drive

LAPD hardware

LAPD

Timedmanagement

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Mail-box /receive

send

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Figure 3-17 Power control flow

The handover decision and power control of the BSC system provides the following features:

1) Distributed processing system. Radio link control functions such as handover decision and power control are distributed to LAPD boards and BTS, which not only results in more efficient use of the power processing capabilities of the subsystems but also improves the system security.

2) Reduced workload of the GMPU. In case of full traffic load, the CPU occupancy ratio of GMPU remains at 20% or below. This ensures the reliability of the system and reserves sufficient processing capability for future function and capacity expansion.

3) Supporting dynamic configuration of parameters.

4) Handover decision functions, including:

Basic cell sorting. Rescue handover (under conditions of TA, bad quality, rapid drop of power level,

or interference, etc.). Border handover. Layered and hierarchical handover. Fast-moving handover. Traffic load handover (including LOAD INDICATION). Directed retry. Forced handover.


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Handover candidate cell query. IUO cell handover

5) Power control functions, including:

MS (uplink) power control, and BTS (downlink) power control. Initial power control. Dynamic power control.

Power and handover controls are discussed in detail in the following text.

Power control means that BSC adjusts the output power of the MS or BTS (or both) within a certain range.

The purpose of power control is to improve the usage of frequency spectrum and to extend the life of MS batteries.

For calls which have been established between MS and BTS, if the received signal quality is high i.e. high transmission power, the output power of the transmitting end can be decreased without any affect on the quality of the established call. This reduces the interference caused by high power signals. The BSC system implements dynamic power control over every MS and BTS.

Multiple kinds of algorithms can be used for power control, including the ETSI GSM05.08 algorithm HW-I algorithm and HW-II algorithm. Huawei dynamic power control algorithm sets up a reasonable model according to the actual usage environment of mobile stations and under the premise of keeping a high voice quality, accomplishes the task of minimum power output by modifying transmission power gradually. In addition, the model is a statistical model among the MSs of a cell, which takes into consideration of the interference between respective MSs and the changes of circumstances. Therefore, it resumes even more reasonable state after being used many times, i.e. it can do better in representing the actual conditions of MSs.

An MS may leave its serving cell, and the transmission quality of calls may degraded to a level even under the specified lower threshold power level due to interference or weak signals. In this case, the calls in progress can be switched from one cell to another cell automatically to prevent the degradation of the communication quality or the failure of the established calls.

Huawei handover algorithm is used in BSC. This algorithm is implemented on the basis of the power control algorithm, by considering the coverage of a certain cell and the border conditions of special cells. The Huawei handover algorithm improves the network capacity and service quality effectively.

3.3.6 BTS Management

As one of the functional modules of BSC, the position of BTS Management (BTSM) module in BSC is shown in Figure 3-18.


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OMC

MSC

OMC TRXTRX

BSC

TRX

TRXTRXTRX

TMU

BTS

BTS

A

Abis

BSS

Um

Um

TMUBTSM

PCUSGSN

Pb

Gb

Figure 3-18 Structure of a BSS

The BTS management module of BSC is responsible for BTS maintenance, data configuration, dynamic modification of BTS data, software loading, equipment test, real-time alarms monitoring, forwarding various test commands from OMC and returning the results of these commands to OMC.

The BTS management module communicates with the BTS via the OML (Operation and Maintenance Link) of the Abis interface.

The OMC can perform remote and near-end maintenance over the BSS.

The functional structure of the software system of the BTS management is shown in Figure 3-19.

BTS Management Module of M900/M1800 BSC

BTS

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Figure 3-19 Structure of BTS management module

BTS software loading management is mainly responsible for remote loading and activation of board software.


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BTS data configuration management is mainly responsible for the normal running of the BTS, including sites and cells initiation.

Dynamic data configuration management supports the online data configuration of the BTS running in the network.

GPRS service flow management supports the packet-based service flow. It re-sends channel attributes to BTSs when dynamic channel conversion (TCH<-->PDCH) occurs, and re-establishes channel connection and forwards direct message between PCU and BTS when the channel coding scheme on air interface changes (CS-1/2<-->CS-3/4).

BTS equipment running management is responsible for daily maintenance and management of the BTS equipment during normal operations including maintenance and management of running state of every object level, real time monitoring of BTS boards and real time query of BTS attributes, etc.

The BTS maintenance module provides a powerful test and diagnosis function, which helps to accomplish the task of BTS equipment testing and measurement. It ensures a long-term & reliable running of the system. It can execute or implement the following activities: maintenance message tracing (including BTSM-Abis interface message tracing, BTSM-RR interface message tracing, and BTSM-HTMAIL interface message tracing) and maintenance information traffic control, transparent transfer of information between BTSM and BTS, and handling BTS log information.

BTS alarm management is responsible for handling the fault alarms.

The BTS management of BSC is equipped with highly effective, reliable and powerful management and maintenance functions, featuring:

Powerful maintenance function: BTS management module provides all the functions described in the GSM Recommendations. Besides, it also provides abundant self-defined functions, which guarantees an effective, stable, and reliable running of the BTS, reduces operating costs and improves the quality of services.

Easy operation: It adopts user-friendly GUI, making operations easy and convenient.

Openness: It provides the completely object-oriented BTS maintenance platform, supports maintenance and management for all level objects of BTS. The system can be easily expanded and upgraded.

3.3.7 Operation & Maintenance Management

The operations and maintenance of BSC adopt the client/server architecture.

Operation and maintenance commands are sent to a certain maintenance module in BSC by the maintenance console of OMC through BAM. After it receives the operation


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and maintenance commands, the maintenance module executes these commands and returns the results to OMC, or transfers the commands to other modules. It will forward results to OMC after the operation and maintenance task is completed.

In hardware structure, operation and maintenance management comprises mainly the following parts: GMPU, BAM, WS, and communication links between these parts. (Communications between GMPU and BAM are realized by MCP through maintenance link, and communications between BAM and the workstation is via the TCP/IP protocol of the network cable or other communication links)

In software structure, operation and maintenance management is realized by GMPU program, BAM program, M900/M1800 OMC Shell, and M900/M1800 OMC maintenance console. To do operation and maintenance, first run the maintenance console on workstation, and the maintenance console will setup connection with BAM program. After the user issue a command from the OMC workstation, the command is first transmitted to the BAM program, in turn BAM sends the command to the O&M system via the MCP HDLC link. The O&M module analyzes the received command.

The architecture of the BSC maintenance part is shown in Figure 3-20.

BSC

Maintenancemodule.

OMC

MaintenanceconsoleOther modules

in BSC

Other application consoles

BAMHTMAIL

Figure 3-20 System structure of the maintenance part

Main characteristics of maintenance operations in BSC include:

I. High reliability

The BSC is designed with full redundancy and fault tolerance techniques by applying backup systems, multi-level distributed control, multi-channels, mutual assistance and system reconfiguration.

II. High efficiency and ease in operation

In software designing of BSC, many advanced technologies are used, such as Object Oriented Programming (OOP), client/server architecture, computers network and visual multi-window.


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III. Openness

The BSC incorporates the network and distributed database technology, complying with the ISO/OSI (Open System Interconnection) standards. And the BSC can be equipped with CD-ROM, tape drive, and printer. Terminals can be easily expanded.

IV. Client/server architecture

The BAM integrates the communication server and database server. Various maintenance and operation tasks are executed in the client/server mode. Simultaneous maintenance and operations from multiple remote and near-end points are supported.

V. Powerful tracing and monitoring function

The BSC system provides powerful tracing and maintenance functions for GSM network interfaces and links. It can trace GSM interfaces e.g. Abis, Um, and A-interfaces, and provide detailed tracing information. It also enables flexible maintenance and management for LAPD and A-interface SS7 signaling links.

VI. GLAP software loading function

Dynamic loading method is used for the GLAP software upgrade without affecting the traffic processing. When loading is completed, the system will automatically switch to the new GLAP software version.

3.3.8 Performance Management

Performance management of the BSC includes performance measurement, flow control, and resource check, all driven by events (time events). Flow control includes the flow control inside the system and that at the Abis interface, resource check includes the audits activated by timer and that by the maintenance console.

I. Performance measurement

The BSSOMAP module accepts performance measurement tasks initiated by the OMC traffic statistics console and schedules them centrally. It notifies the relative modules to start/stop measurement, eventually collects and processes measurement results, and send the result to the OMC statistics console.

Performance measurement tasks can be scheduled. For example, a performance measurement task on a cell starts on July 6, 1998. The statistics days is 60 days. The measurement is conducted between 9:00 am to 14:00 pm with 5 minutes cycles. The task scheduling is hence driven by the absolute timer in the system.


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The measurement results are sent to the OMC traffic statistics console once a second. To equalize system loads, 4 measurement results are sent to the OMC traffic statistics console every time.

Through OMC traffic statistics console a user can perform the following tasks.

1) Set up a measurement task

The task number and parameter will be checked for validity. If these are illegal then error will be sent to the OMC traffic statistics console. If these are valid then the absolute timer is reserved for registered task.

2) Delete the measurement task

The task number will be checked first. If it failed to pass the check, error indications will be sent to the OMC traffic statistics console. If otherwise it succeeded in passing the check, this task will then be deleted.

3) Query the task state

The task number is checked. If it is correct, fill in with the corresponding state, otherwise fill in indication of "No such task".

4) Acknowledgment of received results

The acknowledgment is made in the form of expecting the next frame. When the message is acknowledged, the received measurement result is deleted.

II. System's flow control

Flow control of the BSC includes flow control inside the system and on the Abis interface.

Internal flow control conducts flow control over the whole BSC based on the GMPU loading software and its processing capacity. The internal flow control monitors key system resources including CPU loading, message queues and evaluates system flow level. Internal flow control monitors the system resources once a second, and updates the internal flow level once every 30 seconds.

The flow control on the Abis interface is exercised specifically over the loading of radio resources, based on the cell so as to reduce traffic volume at the source. The flow control on the Abis interface handles the overload messages from the Abis interface, calculates the flow level in the cell, and provides appropriate control over the access of the MS in the cell.

1) Design of internal flow control

Traffic flow is classified into 12 levels. The higher the flow level is, the lower the service level.

Level 0 is a normal running level; levels 1-11 are flow levels for the whole BSM. At different levels, this module provides different levels of service. When flow control


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exists in the BSC system (flow control level is higher than 0), packet service access is prohibited.

2) Design of traffic control on the Abis interface

Traffic is classified into 12 levels, with cell as the smallest control unit. The higher traffic level means lower service level.

Level 0 is a normal running level, levels 1-11 are the flow level for a specific cell. At different flow levels, the cell provides different service levels. When there is flow control (traffic control level is greater than 0) in a cell, new packet service access is prohibited.

3) Reference configurations of corresponding parameters

Reference configurations of corresponding parameters for traffic control at the Abis interface and internal traffic control are shown in Table 3-1, Table 3-2, Table 3-3 and Table 3-4.

Table 3-1 MS access delay control parameters

MS access delay parameter t0 t1 t2 t3 t4 t5 t6 t7 t8 t9 t10

Reference value

(unit: second) 10 30 60 90 120 150 180 200 210 240 255

Table 3-2 Parameters configuration for access rejection on causes set

CHAN REQ access cause S1 S2 S3 S4 S5

Emergency call - - - - - Location update - - - - Y Paging response - - - Y Y

Call re-establishment - - Y Y Y MO call - Y Y Y Y

Other causes Y Y Y Y Y Note: "Y in the table indicates the causes set.

Table 3-3 MS minimum allowed access level (RXLEV_ACCESS_MIN)

RXLEV_ACCESS_MIN L0 L1 L2 L3 L4 L5 L6 L7 L8 L9 L10Reference value 0 6 12 18 24 30 36 42 48 54 60

Note: 0 ≤ Lx ≤ 63, x=0 ~ 10

Table 3-4 Cell reselection parameters CRO (CELL_RESELECT_OFFSET)

CRO R0 R1 R2 R3 R4 R5 R6 R7 R8 R9 R10Reference value 0 6 12 18 24 30 36 42 48 54 60

Note: 0 ≤ Rx ≤ 63, x=0 ~ 10


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III. Resource check

The resource check function of the BSC ensures reliable system running by providing powerful self-test for faults and recovery functions. This function automatically corrects the running errors that can take place in various abnormalities, check the usage of system resources, and ensures correct allocation, use, and release of various resources. To prevent the accumulation of errors generated during the long-term running of the system that can lead to deterioration of system processing capability, the function corrects various faults so as to ensure the reliable running system.

1) Resource check initiated by BSC

This function is dispatched by the CHECK module, and conducted in the various modules. It can be performed in two ways i.e. checking initiated at the maintenance console and timed resource check every day. It mainly involves:

The occupation of the memory resources, for example, allocation and release of the call control block.

The occupation of A-interface circuit resources. The consistence between radio resources occupation and state. The occupation of GNET board resources. The consistence between the signaling link occupation and state. BCCH mutual-assistance and carrier mutual-assistance state check. Miscellaneous, including the consistency of the system control parameters.

2) Resource check initiated by PCU

To eliminate the inconsistency between the PCU and BSC due to certain abnormalities, it is necessary to check resources periodically between the BSC and PCU. The check is initiated by PCU, and BSC is responsible for correcting the inconsistency between the two entities. The check mainly involves:

Type and state of PDCH channels. PCIC state. Cell state.

3.3.9 Alarm Management

I. BSC alarm management

BSC alarm management is responsible for collecting and handling BSC alarm messages, and sending these alarms to the alarm console and alarm box. When an abnormality is detected in the BSC software or BTS equipment, the BSC sends alarm message to the visual or audible interface through OMC to inform the maintenance staff about the abnormality. It also recommends solution for the reference of maintenance staff.

The system structure of alarm management is shown in Figure 3-21.


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BSC alarm box BTS alarm box

OMC

BSC

Alar

m ha

ndlin

g

BTSMU

O

BTSMU

O

Figure 3-21 System structure of the alarm management part

Note:

As shown in the above figure, the boards at the BTS side responsible for information interchange with BSC are OMUs in BTS2.0. But in BTS3.0 they should be TMUs.

Alarm management of BSC features the following characteristics:

1) Real time alarm indication

When an alarm is generated in the main system, the system can handle the alarm immediately and send it to the user interface. The maintenance staff are informed timely so that they can take necessary actions and fix the problem quickly.

2) Hierarchical control

In BSC system, the generated alarms are of four levels according to the assigned priorities. Critical alarms have the highest priority.

3) Convenient and flexible display and operations

Alarm messages in the system can either be inquired from the OMC alarm console or from the alarm box. The alarm box is connected with BSC, when an alarm is generated, the BSC sends the alarm message to the alarm box, which can produce audible and visible alarms.

For different levels and different types of alarm, alarm box can produce different alarm sounds and light. A maintenance person can inquire the alarm data and read the detailed alarm information on OMC alarm console as well. For example, if a board is faulty, the frame and slot position of the faulty board can be located by reading the


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detailed information in alarm console. In the alarm console, the probable cause and its solution is also suggested.

After the collection of alarms messages from different modules, it processes the alarm information and then sends it to the user interface. Following are the processing modes of the alarms.

For alarms to be sent to BAM, those of higher priorities will be sent first. For alarms to be sent to BAM, BSC uses the acknowledged mode to send alarms

parts by parts. That is, after it has sent an alarm message, it shall wait for the acknowledgement from BAM before sending the next.

Alarms to be sent immediately to the alarm box. 4) Easy remote alarm box operation

Through the alarm box maintenance interface at the alarm console, various operations on the alarm box can be easily conducted, for example, alarm sound control and the alarm indicator of a certain subsystem, or alarm box resetting.

5) Alarm filtration

The alarms can be filtered according to the user's requirements. Alarm filtration is enabled by adding alarm in filter table in the data management console. User can set alarm conditions based on actual needs. BSC will analyze the conditions in the table and carry out the filtering operation. Recovery alarms can not be filtered. A user can inquire alarm's filter conditions at any time from the filter table.

II. BTS alarm management

The BTS alarm management is one of the functions of the BTS maintenance management, which provides detailed information for maintenance and control of the BTS equipment.

Alarm information about boards in BTS are collected by OMU (or TMU) and sent to BSC through the maintenance link.

The BTS alarms are first processed by the OMU (or TMU), which will take different fault recovery measures according to the alarm, such as board reset or data reconfiguration. If the BTS can not handle the alarm messages, it will inform the BSC. When BSC receives the alarms from BTS, it saves alarm messages in the alarm buffer and transfers them to the OMC alarm console for display. At the same time, BSC can drive the BTS alarm box to provide audible and visible alarms.

The alarm filtration function of BTS alarm management allows a user to get filtered alarms according to his requirements. After the maintenance console issues alarm filtration messages via the BSC, the alarms are filtered and the BTS will no longer reports them to the BSC. Likewise the BSC can issue alarm de-filtration message. After the BTS receives such commands, it releases the masking on the alarms, thereby those alarms can be reported to the BSC normally.


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3.4 OMC Software

The design of OMC software adopts modular structure for easy expansion and upgradation. This modular approach also makes system more open and flexible.

Logically, OMC software can be divided into three parts: BAM software, OMC server software, WS software (including OMC Shell and software of application consoles). TCP/IP is used for communication among these parts, as illustrated in Figure 3-22.

BAM

Alarm server

Config. serverOMC SHELL

LAN

...

...

WS

OMC Server/ DB

BAM ...

...

TCP/IP

Dat

a m

anag

.

Mai

nten

ance

Traf

fic s

tat.

...Windows

Sun Solaris/Sybase

Figure 3-22 OMC system software structure

Back Administration Module (BAM) is the bridge between the BSC and OMC system, in which BSC configuration data is stored. In addition it also functions as server module of application services system.

OMC Shell and respective application consoles run on Windows platform, providing visual interface of OMC system.

OMC server runs on Unix platform. Its software system mainly includes communication server, configuration server, alarm server, traffic statistics database, upper-level NM interface, etc. Sybase is used to build databases.

Principles and techniques of OMC software system will be introduced in detail in the following sections, including BAM, OMC Shell, application console and OMC server.

3.4.1 BAM Software

As described above, BAM can serve as communication interface and application server, and is also responsible for storing and forwarding alarm messages and traffic statistics, etc.


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BAM has key position in OMC system. It adopts the object-oriented software design approach. BAM is connected with BSC through MCP card.

BAM is based on modular structure. Respective server modules and communication drive modules are relatively independent and driven by messages, as shown in the Figure 3-23. Respective functional modules can be dismounted.

Mic

rok e

rne l

Traffic statistics server

Maintenance server

Other server

MCP module

TCP/IP module

Other communication module

HDLC

LAN

Figure 3-23 BAM software logical structure

The BAM software structure enables that every functional module can be installed/uninstalled on corresponding layers without any relation to the bottom layer of hardware or even the equipment drive modules. Each module offers excellent openness, expandability and transplantability.

Micro-kernel is responsible for loading and dispatching equipment driving module and application server module.

Server module on application layer is an important part in the system as it is not only responsible for coordinating transmission of messages to the application layer and multi-point maintenance, but also implements the maintenance and share of the configuration data in the related parts of the system.

3.4.2 OMC Shell

OMC Shell is a user interface to manage, operate and maintain different parts of the GSM system. OMC Shell is used for visual management of NEs of the entire Huawei GSM system through WS.

OMC client programs is based on Windows operating system and provides users friendly graphical interfaces and detailed on-line help.


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I. Structure

The position of OMC Shell in OMC system is shown in Figure 3-24. OMC Shell is the link among application consoles. It is responsible for the communication between application console and BAM or OMC server/DB.

BAM 1 Server DBBAM 2

Application console nApplication console 2Application console 1

OMC SHELL

OMC communication network

BAU

Figure 3-24 OMC Shell location

OMC Shell program consists of user interface module and communication module. User interface module provides visual operating interfaces such as tree-like list and map windows. Through the interface, GSM equipment state can be observed and operation, maintenance and management can also be performed directly. Communication module is mainly responsible for communication management.

II. Function description

OMC Shell functions include maintenance measures and service functions.

OMC Shell interface mainly consists of object list and map windows. In object list, the hierarchical relation among GSM objects is represented in tree-like structure. Map window displays the actual geographical distribution and connections of each object.

Different kinds of GSM objects can be represented with different icons and the connections in between these nodes are shown by lines. GSM objects in object list and map window correspond respectively.

By using node icons, many operation can be executed such as object management, running respective application consoles, system time setting, viewing version number and operation logs, etc.


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The change of object node icon reflects different state of the object, including communication & connection state and alarm display. For example, a cross mark on node icon shows communication breakdown between OMC Shell and BAM. A slash mark shows communication breakdown between BAM and BSC. A red dot indicates alarm. The greater numbers of dots implies higher alarm level.

3.4.3 OMC Application Console

OMC application console is a classified collection of service functions, which include:

Maintenance console Traffic statistics console Data management console Alarm console Test console Data configuration console Base station maintenance

OMC is a central application console for the whole network. Its client terminal can directly access alarm server to view, query and print alarms.

Other kinds of application consoles are generally composed of a client terminal and a server. The client terminal provides operation and maintenance interface. The server responds to the operation requests from the client terminal, transforms them into operational commands, and send the operational results to the client terminal, as illustrated in Figure 3-25.

BSCBAMWS

Figure 3-25 Logical structure of a application console

3.4.4 OMC Server

Various service programs run in the OMC server, including communication server, database server, etc. Database server responds to the request from BAM or application consoles, and manages various data with DBMS interactively. Communication between OMC server and other parts of OMC is accomplished by the communication server.

The basic structure of OMC server is shown in Figure 3-26.


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Sybase

Communication service

Configuration Alarm Trafficstatistic Subscriber Log

Figure 3-26 Logical structure of OMC server

Logically, respective parts in OMC system are connected with communication server located at the center of OMC server. Star-connection is then formed. Message transmission is coordinated by the communication sever. Thus, the components can communicate with each other but are independent to each other, which improves the expandability of the system. The specific structure is shown in Figure 3-27.

managementAlarm Configuration

managementTraffic statistic

reportLog

management

Communication server

Sybase

BAM BAM WS WS

TCP/IP

TCP/IP TCP/IP

Figure 3-27 Logical connection of OMC server


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Communication server is the core of the whole system, it connects other parts through application agents. It provides an identity to each application part connected to it. In message transmission, communication server receives message from other parts and determines its destination, sends the message to destination or processes it accordingly.

Configuration management module provides node and link messages for OMC and also records information of operator connected to the OMC server.

Log management module records the operators' work in OMC Shell and operation state of application consoles.

Alarm server is the core of alarm management module. It maintains all alarm messages of modules in the whole system, such as fault alarms, event alarms and recovery alarms. It also provides real-time display and conditional inquiry at Client.

Traffic statistics management server collects original performance measurement data from BAM, writes them in database of OMC for processing, and generates statistics data for the application console to produce measurement reports.

3.5 BSC Operation & Maintenance System

This chapter gives a systematic description of the operation & maintenance of BSC.

3.5.1 System Structure

The operation & maintenance system of BSC encompasses mainly:

I. BAM

BAM is an external operation & maintenance communication interface of BSC, handling communication with the OMC system and delivering the server function of part of OMC application consoles.

BAM functions in OMC system in two ways. On one hand, it acts as a communication bridge between OMC and BSC. It can transmit maintenance and operation commands from OMC to BSC and return the command results to the corresponding terminal. On the other hand, it acts as a server in Client/Server models. Besides database management and management of task testing and traffic statistics, it also saves and forwards alarm message and traffic statistics data. It can also save various kinds of important data to hard disk and backup them to CD or OMC server if necessary.


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II. WS

OMC WS provides a visual interface of maintenance and management to GSM network elements. It is a computer that runs Windows operating system. The operating software includes:

1) OMC Shell

OMC Shell serves to browse and view the configuration state and node information on the OMC network and monitor OMC network. The running environment for the OMC Shell is WINDOWS 9.x or WINDOWS NT.

2) Client program in each application console

The application console is a classified set of some service functions, including data management, maintenance, test, alarm, performance measurement, BTS maintenance and so on. Through these application consoles, a user can perform all operations in OMC system.

All maintenance and management operation can be conducted on one or more WSs. The number of WSs can be configured according to the system capacity.

III. OMC server

OMC server is a workstation that runs SUN Solaris operation system. The number of OMC server can be configured according to the system capacity.

OMC network configuration data and subscriber data are stored on OMC Server. OMC server employs Sybase as data base platform.

OMC Server provides the following functions:

Storage of OMC configuration messages and provision of necessary configuration data to the OMC Shell.

Storage of traffic statistic data. Storage of alarm data.

3.5.2 System Features

Main characteristics of BSC O&M system include:

I. High reliability

The BSC is designed with full redundancy and fault tolerance by applying backup systems, multi-level distributed control, multi-channels, mutual assistance and system reconfiguration.


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II. High efficiency and ease in operation

In BSC software designing, many advanced technologies are used, such as Object Oriented Programming (OOP), client/server architecture, computers network and visual multi-window. It is convenient to conduct operation.

III. Openness

The BSC incorporates the network and distributed database technology, complying with the ISO/OSI (Open System Interconnection) standard. And the BSC can be equipped with such peripherals as the CD-ROM device, tape device, and printer. Terminals can be expanded.

IV. Client/Server architecture

The BAM integrates the communication server and database server. Various maintenance and operation tasks are all executed in the client/server mode. Simultaneous maintenance and operations from multiple remote and near-end points are supported.

V. Powerful tracing and monitoring function

The BSC system provides powerful tracing and maintenance functions for GSM network interfaces and links. It can trace GSM interfaces standard e.g. Abis, Um, and A-interfaces, and provide explanation and display for traced information. It also enables flexible maintenance and management for LAPD and A-interface SS7 signaling links.

VI. GLAP software loading function

Dynamic loading method is used for the GLAP software upgrading without affecting the services processing during the loading. When loading is completed, the system will automatically switch to the new GLAP software version.

3.5.3 System Functions

OMC interface provides data management, equipment maintenance, traffic statistics and alarm handling for the BSC system, including

Data management Maintenance function Traffic statistics Alarm function Data configuration BTS management.


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I. Data Management Function

Being a part of the GSM OMC database management system, the BSC data management sub-system (data management console) is used to query the data needed in the operations of the BSC system through OMC, including hardware configuration data, BSC data, BTS data, cell management data, handover management data, power control data, channel data, trunk data, SS7 data and alarm parameters etc.

The interface of the BSC data management system contains bivariate tables, which are in one-to-one correspondence with the database relational tables.

II. Maintenance Function

The purpose of the maintenance functions is to monitor and query the running state of the system and provides equipment with operation and maintenance functions. The maintenance functions include:

1) Routine maintenance function Query software version

In the BSC system, the version numbers that can be queried include main version number, attached version number, and description of the version.

View module state

The state of all BM modules in a BSC can be viewed. Inactive modules are indicated by the asterisk "*".

2) Control startup function

The control startup function consists of the following parts:

Board query & control

Through OMC maintenance console, maintenance staff can check the configurations and states of boards of each module, query and reset designated boards. Normal/abnormal running of active/standby boards and software versions can be checked. TS (time slot) occupancy can be seen and real-time update can be enabled according to the changes of TS occupancy state of the network boards.

When OMC issues the command of check equipment state, the maintenance console sends the command to the special maintenance module in the GMPU via BAM. The maintenance module checks the configurations of all boards and sends the results to the maintenance console in the form of packets. At the same time, it labels the state of boards in the frames of BSC. If the state of a board in a plug-in frame has changed, the maintenance module will send information about the new state of the board to the OMC maintenance console so that the maintenance staff can observe the real-time refreshed information of boards.

LAPD link maintenance


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The maintenance personnel can query and reset the LAPD links of the GMPU via the maintenance management system.

Circuit control

Circuit control refers to the trunk circuit control used in the system. Maintenance staff can execute the various operations on the designated trunk circuit through OMC maintenance console, including state query, circuit blocking, circuit unblocking, circuit reset and checking the circuit in designated state.

Query, confirm and operation of half-permanent connection. Immediate switchover

To guarantee the safe and reliable operations of the system, the BSC system provides proper redundancy. Active and standby boards are configured in the system. Active boards provide service functions in normal operations while standby boards are backups of the active boards. In case of any abnormality in the active board the system switches to the standby board, so that the system can operate safely and continuously.

The active/standby switchover of the system has two modes: the first is when the active board fails, the system performs automatic switchover, and in the other mode maintenance staff can execute the switchover of the equipment through the maintenance terminal by using commands. After immediate switchover command has been sent to the main system, the special maintenance module informs the relative module to execute the switchover. Equipment that can be switched over includes GMPU, GNET and clock boards etc.

Hierarchical restart

Maintenance staff can execute level-1, level-2, level-3 or level-4 restart through the OMC maintenance console. Different influences will be generated by restarting of different levels and loading of programs and data.

On receipt of the Hierarchical restart command, the system starts resetting after some time delay and alarm will be generated.

View HDLC link state

This is to check the states of HDLC links on the GMCC, GSNT, and GCTN boards.

BSC system reset

Maintenance staff can reset the BSC remotely via OMC maintenance console.

Unlike the hierarchical reset, BSC system resetting is an operation on all modules. It clears the software resources of all BM modules including call and connection, and sends reset messages to MSC. The operation will also refresh the faulty circuit state of this BSC.

After the BSC system reset, the system will generate alarms.

System resource check


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During resource checking, the resources with inconsistent states are released by force so that the system can run reliably. The resources allocation/management module is for preventing the suspension of resources. Here resources include not only radio channels, GNET board timeslot, CIC, etc., but also the data buffer in the module, if the data buffer is not released normally after used, this can result in the lowering of system efficiency or even system collapse.

To avoid any inconsistency between the PCU and BSC due to abnormalities, it is necessary to carry out periodic check of the resources between the BSC and PCU. The check is started by the PCU, and the BSC is responsible for correcting the inconsistencies between the two. The check involves the types and states of the PDCH, states of the PCIC and cell, etc.

Loading GLAP board software

This loading is done dynamically to complete the upgrading and replacement of GLAP board software. The detailed method for the loading of GLAP board software is as follows.

Loading software is conducted when the GLAP board is running, and will not affect the current services. It dynamically write the software into the Flash Memory of the GLAP. When the loading is finished, the new software will be run.

Loading board software is determined by operators and the command is sent from OMC.

3) Tracing and monitoring functions

Tracking and monitoring functions include:

Handover monitoring

When the mobile subscribers move in different areas, handovers might occur, such as inter-MSC handover, inter-BSC handover, inter-cell handover, and intra-cell handover.

With respect to the BSS, handover mainly refers to the last three types. In the maintenance management system of BSC, monitoring and observation can be executed on handover of cells, TRXs and of different types. To establish the observation of handover, dynamic settings can be made on the types of handover, cell numbers and TRX numbers.

When the maintenance staff starts the handover observation request in the OMC maintenance console, the command is sent to the GMPU through BAM. The special maintenance module receives the command and set up the handover observation table to record the handover types, handover cell and TRX that the maintenance staff needs to observe. When the handover occurs, the handling module will send sequentially the message contents of the handover procedure to the OMC maintenance console that has set up handover observations according to the filtering conditions and OMC workstation locations set in the handover observation table.


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When the maintenance staff sets new filtering conditions to the established handover observation, the OMC maintenance console sends the command to the BSC through the BAM service program. After receiving the command, the BSC maintenance module finds the corresponding item in the handover observation table and reset the filtering conditions of the handover observation.

Major filtering conditions of the handover includes cell number, TRX number, target cell number, target TRX number, IMSI and MSISDN.

Observation types include: Incoming cell handover observation, outgoing cell handover observation, intra-cell handover observation, inter-cell handover observation, incoming-to BSC handover observation and outgoing-from BSC handover observation.

Interface tracing

In the GSM system, the contacts and message transfer between entities are all via standard interfaces, which are: A-interface between MSC and BSC, Abis interface between BSC and BTS and Um interface between the BTS and MS.

The maintenance management of the BSC can trace the messages on standard interfaces and provides detailed explanations. For different interfaces, the setting of filtering condition function is provided to facilitate the user's observations of different messages on the interfaces.

For A-interface messages, filtering conditions include: Connectionless messages, DTAP messages and BSSMAP messages.

For Abis interface messages, filtering conditions include: BTS number, TRX number, channel number, MR, radio link layer management messages, dedicated channel management messages, common channel management messages and TRX management messages.

For Um interface messages, filtering conditions include: BTS number, TRX number, channel number, RR (radio resource) management messages, MM messages, CC (call control) messages, call-related SS (supplementary service) messages, call dependant SS messages, and SMS (short messages).

CPU monitoring

The BSC maintenance management system can monitor the present operation performance of the main system, including CPU occupation ratio, AM memory, CPU occupation ratio of AM/CM boards. The system can display if the CPU occupation ratio is normal, overloaded or congested, and can be real-time refreshed dynamically.

Maintenance staff can initiate the CPU load observation by command, which is sent to the maintenance module through BAM service program. The maintenance module returns the CPU load and state to the OMC maintenance console and records the address information of the OMC maintenance console.


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When the CPU occupation ratio changes, the new CPU occupation ratio and state will be sent to the maintenance console.

The operation states of CPU include normal, overloaded and congested. When the CPU occupation ratio is higher than the overload start threshold, the state value of CPU is changed to overloaded. When the occupation ratio of CPU is lower than the overload end threshold, the state value of CPU is changed from overloaded to normal. When the occupation ratio of CPU is higher than the congestion start threshold, the state value of CPU is changed to congested. When the CPU occupation ratio is decreased to the congestion end threshold, the state value of CPU is changed from congested to overloaded state.

Optical channel switchover Reset E1 port on E3M

The BSC maintenance management system can reset an E1 port in the main system.

To reset E1 port, maintenance staff must first decide the E3M board number and E1 port number. This resetting command is sent to the maintenance module in the main system via BAM service program. After receiving this command, the maintenance module interprets and sends this command to the corresponding E3M board. Then the maintenance module waits for the response of E3M and transfers it to the maintenance console, which displays the information of successful resetting or timeout.

Query E1 port on E3M

The BSC maintenance management system can monitor E1 performance of each E3M from BSC unit to TCSM, including E3M board number, E1 configuration and the working state.

To query the E1 port, the E3M board number and E1 port number should be specified first. This query command is sent to the maintenance module via BAM service program. After receiving the command, the maintenance module interprets and sends command to the corresponding E3M board. Then the maintenance module waits and transfers the response of E3M to maintenance console. In addition, the maintenance console also displays E1 port state. If E1 is not configured, the maintenance console would display that the port is not installed, if E1 works normally, the maintenance console would display normal, if E1 line is not connected or TCSM fails, the maintenance console will display the fault. If the query fails, the maintenance console would display timeout.

Query clock output on E3M

The BSC maintenance management system can monitor the E1 through which the current clock signal from MSC to BSC is transmitted

To query the clock output E1 port of E3M board, the E3M board number should be specified first. This query command is sent to maintenance module via BAM service program. The maintenance module would interpret and send the command to


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corresponding E3M board after receiving this command. Then the maintenance module would wait and transfer the response of E3M to the maintenance console. If the query is successful, the maintenance console would display E3M board number, the E1 port number of reference resource and output reference resource. If the query fails, timeout is displayed on the maintenance console.

Query 2k network state on E3M

The BSC maintenance management system can monitor current state of 2k network of E3M in the BSC.

To start querying the E1 port, E3M board's number should be specified first. This query command is sent to the maintenance module via BAM service program. After receiving this command, the maintenance module would interpret and send this command to the corresponding E3M board. Then the maintenance module would wait for the response of E3M and transfer it to the maintenance console. If the query is successful, the maintenance console would display 2k network state table, otherwise timeout would be displayed.

4) Control & parameter settings

Control & parameter settings include:

Memory operations. Clock setting. Setting of backup speed. Settings of overload and congestion threshold of modules. GCKS board control.

5) SS7 maintenance function

SS7 maintenance functions includes:

SS7 signaling message tracing. SS7 message tracing review. SS7 link management. Dummy message operation. State query. SCCP maintenance.

III. Traffic Statistics Function

The traffic statistics subsystem is responsible for the traffic statistics management. It provides traffic statistics task management, view and print of different measurement results. These results are used by network planners to improve the network efficiency.

Its specific functions include:

BSC performance observation. Cell performance observation.


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Observe the intra-cell handover by browsing the intra-cell handover performance measurement task.

Observe the performance of power control by browsing the power control performance task.

Observe the performance and use of the LAPD link by browsing the LAPD protocol performance measurement task.

Observe the performance and use of the SCCP by browsing the SCCP performance measurement task.

Observe the state of the MTP link by browsing the MTP performance measurement task.

Observe the performance and use of cell broadcasting by browsing the cell broadcasting performance measurement.

Observe the performance of the A-interface by browsing the A-interface performance measurement task.

Observe the completion condition of the initialization process by browsing the site and cell initialization performance measurement.

Observe the frequencies of the adjacent cells by browsing the neighbor cell performance measurement task.

Observe the current signal quality of service of the cell by browsing the cell service quality measurement task.

Observe the running of the CPU by browsing the CPU running measurement task.

IV. Alarm Function

Alarm system stores all types of alarms in the system and provides browsing, querying, printing and clearing of alarms. Specific operations includes:

Event alarm browsing. Fault alarm browsing. Real-time alarms indication including the browsing of real-time alarms (Note:

alarms can be browsed conditionally according to user selection). Query of event alarms. Query of fault alarms. Query of alarm history. Real-time alarms printing. Alarm messages clearance (including event alarms and alarm history).

V. Dynamic Data Configuration Function

Dynamic data configuration is also called online data configuration, that is, modifications of system configuration data and system attribute data can be done without resetting the BSC. This is very important for smooth expansion of the system capacity and network planning & optimization.


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If a BSC is in operation and a user wants to modify its data, reset of BSC means interruption of BSC and its BTS services. Dynamic data configuration facilitates the implementation of data modification and minimizes the impact on the current service.

1) Operation method

A dynamic data configuration service system runs on the WS It is responsible for implementing the function of dynamic data modifications with online help. The service system simultaneously handles data validity, consistency, integrity, and tolerance check automatically. And the user does not have to worry about the content and method of the modification, which simplifies the process of dynamic data configuration, conveniences the user, and greatly improves the efficiency and security of dynamic data configuration.

2) Functions

Sites addition/removal: This function can add (or delete) the sites in various networking modes, and even the cells, TRXs, and BTS boards. This function does not affect the other working sites and the circuit-based and packet-based services that have been set up.

Cells addition/removal: This function can add (or delete) the GSM900 and GSM1800 cells, and even the TRXs and BTS boards. This function does not affect the other working sites and the circuit-based and packet-based services that have been set up.

TRXs addition/removal: This function can add (or delete) the TRXs, and corresponding BTS boards. This function does not affect the other working sites and the circuit-based and packet-based services that have been set up. And anti-conflict mechanism has been added specifically for the fault handling function of baseband hopping TRXs and the main BCCH mutual assistance function to ensure that there is no negative impact even if the mutual-assistant TRXs are deleted.

BTS boards addition/removal: This function can add (or remove) a board at the BTS side.

Modification of cell system information: This function can modify the system information transferred to the cell without affecting the circuit-based service already set up in the cell, but may affect the established packet-based service.

Modification of handover parameters: After the modification, handover can be performed based on the new parameters. This function does not affect the normal working of the cell and the established circuit-based and packet-based services.

Modification of cell power control parameters: Power control parameter can be readjusted according to the system requirements without affecting the circuit-based services and packet-based services.


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Modification of clock parameters: This function can modify the clock mode of the site and clock parameters 1 and 2 without affecting the normal working of the site and established the circuit-based and packet-based services.

Modification of BTS and network color codes: This function does not affect the normal working of the other cells and the established circuit-based and packet-based services.

Modification of cell state: Through this function a user can change the cell state from equipped to unequipped state and vice versa. It is similar to the cell addition/removal function except that the originally configured data does not need to be configured. This function does not affect the normal working of the other cells and the established circuit-based and packet-based services.

Modification of cell attributes: This function can modify the interference band threshold, saturation threshold, and DC bias voltage threshold, without affecting the normal working of the cell and the established circuit-based and packet-based services.

Modification of cell alarm threshold: this will not affect the normal working of this cell or the established circuit-based and packet-based services.

Modification of carrier frequencies: This function can modify the frequencies of the TRXs. Modifying the TRX frequencies of non-active BCCH of non hopping cell will not affect the calls already set up, but will affect the packet-based service.

Modification of cell's frequency hopping attributes: The software of the BSC supports timeslot hopping and can dynamically modify the hopping parameters of various channels in the cell, including MA table, MAIO, TSC, and HSN. As for the RF hopping cell, this function can modify the number of frequencies involved in hopping, for the baseband frequency hopping cell, the function can modify the frequency values involved and change the cell from a hopping cell to non-hopping one and vice versa. This function does not affect the normal working of other cells and the established circuit-based and packet-based services.

Modification of TRX attributes: This function can modify the static power level, saturation threshold and DC bias voltage threshold of the TRX.

Modification of channel types: This function can change any active BCCH to TCH, SDCCH or PDCH, without affecting the established circuit-based service. If the modification of channel type involves the PDCH before and afterwards, this will affect the packet-based service.

3) Dynamic data configuration reliability insurance

In addition to the reliability check mechanisms provided by the OMC, the BTSM provides such mechanisms as timed retransmission, added response, and alarming so that data can be configured correctly and completely in the BTS. In case of BTS


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maintenance link fault, the dynamic data configuration commands to the BTS can not be sent, this will cause inconsistency between the data at the site and that in the BSC, which will affect the working quality of the system. At this time, the BTSM will periodically re-issue dynamic data commands to the BTS and issue alarms to the OMC.

VI. BTS Maintenance Function

The BTS maintenance module of BSC provides rich BTS maintenance functions to the users. Through these operations, users can guarantee the highly efficient, stable and reliable operations of BTSs. The operation costs will be reduced and communication service quality will be improved.

1) BTS software loading management

BTS software loading is one of the most important functions of BTS maintenance. Since widely distributed BTSs are controlled by single BSC so it is very complicated to replace the BTS board software at the location. BSC provides remote software loading function of BTS, thus all software of the BTS can be loaded from the OMC terminal. BTS software loading is required in two cases.

When the BTS maintenance unit is powered on or reset, it requests board software from the BSC, and BSC will load the BTS software automatically. The version of the software loaded in BTS can be configured in the slot description table from the OMC data management console. If the software version stored in the BTS is consistent with that configured in the data management console, the software will be directly activated and no software loading will be needed.

Software version up-gradation. The BTS maintenance unit can keep two software versions for each board. When the software version is to be updated, forced loading of the BTS software will be executed. OMC maintenance console shall display the whole process and loading time of BTS software. The OMC can abort the software process if necessary. After the BTS software is loaded, it need to be activated because the loaded software is stored in the O&M unit at the BTS side. Activation can be performed independently. Select the software version to be activated and designate the board to be activated, then force the BTS to run the new software version. Activation can be performed on multiple designated boards at the same time. During the activation, the activation reports are generated. And the OMC BTS maintenance console will display the progress of the activation and generate activation success report, and prompts which board has been successfully activated.

2) BTS data configuration management

Another important function of BTS management is BTS data configuration. It is responsible for the initialization of the BTS and ensures the normal working of the BTS. In addition, it has the functions of BTS data configuration and modification in service.


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During normal running, operation parameters are issued by BSC to BTS. The BTS maintenance module in BSC enables the BTS data configuration process and configures such information as BTS parameters, cell parameters, frequency parameter, channel parameters alarm threshold and BTS software & hardware configurations. In addition, BSC needs to configure the BTS network structure data to ensure the BTS functioning in different network topologies.

The initialization process of the BTS has two stages: site initialization and cell initialization.

Site Initialization

Configuration of the logic object of the BTS. Configuration of the BTS hardware equipment. Configuration of the site attributes. Configuration of the BTS networking. Sending BTS site in-service commands.

Cell Initialization

Cell initialization includes: TEI setup. Signaling connection setup. Service connection setup. Configuration of cell attributes. Configuration of TRX attributes. Configuration of TRX extended attributes Configuration of RC attributes Configuration of RC extended attributes Configuration of channel attributes. Alarm threshold setting. Sending cell in-service commands.

3) BTS equipment operation management

The BTS management module of BSC helps the users to check the states of BTS equipment and objects. It also provides necessary maintenance measures. BTS maintenance is object-oriented. These objects include BTS, cells, BT (Baseband Transceiver), RC (TRX), channels, and boards.

Functions provided to BTS

Getting BTS software version, which helps query the information of all software running in BTS and can display BTS software number, version number, supplementary description, date of version release and version description.

Getting BTS attributes, including supplier flags, maintenance link property, site input parameter, site output parameter, terminal equipment flag, clock property, hardware configuration and software configuration.


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BTS hierarchical resetting, when the BTS fails or BSC is restarted, the hierarchical resetting command will be issued to the BTS. Four levels of resetting commands are defined for different situations.

Clock Selection, two clock modes are available i.e. free-run mode and locked mode, which can be selected in the BTS maintenance console.

It provides CPU performance report i.e. CPUs load and occupancy of the different boards.

Transparent message transmission from OMC to BTS.

Functions provided to cell

Sending the system information about the cell so that the BSC can select to transfer 1, 2, 2bis, 2ter, 3, 4, 5, 5bis, 5ter, and 6. To support GPRS, system information SI7 and SI13 should also be contained.

Changing the cell state to locked or unlocked. Getting cell attributes, including admin state, running state, and BTS data. A forced cell handover can be provided through software command, which can be

initiated from OMC.

Functions provided to BT

Getting baseband attributes. Changing the admin state to LOCKED, UNLOCKED, or SHUTDOWN. Querying the channel state. Forced baseband handover. TRX hierarchical resetting. TRX handover. TRX blocking/unblocking.

Functions provided to RC

Getting RC attributes. Changing the management state, which can be changed into LOCKED, or

UNLOCKED. Shut down the power amplification of RC.

Functions provided to channel

Getting channel attributes Changing the management state, which can be changed into BLOCKED,

UNBLOCKED, or SHUTDOWN. Forced channel handover Intra-BSC channel handover

Functions provided to BTS equipment management

Querying the state of BTS equipment. Resetting the BTS board. Querying information about the BTS board.

4) BTS test management


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To enable the long-term, continuous and stable operations of the system, the use of test and diagnosis functions are necessary for the maintenance of the whole system. BTS maintenance module of BSC provides powerful test and diagnosis function. During operation, intelligent boards execute self-check instantly, and generates the alarms automatically or switchover the boards in case of any fault or abnormality. On the other hand, test tasks can be initiated in the BTS maintenance console.

BTS test functions provided by the BTS maintenance system of BSC are:

Maintenance link test. Loopback from antenna. Loopback from receiver. Self-test of functional objects. Board self-test. CUIC link self-test. Service connection loop test at the Abis interface.

5) BTS alarm management

BTS alarm management of BSC is another function of BTS maintenance management.

During the normal operation of BTS boards will instantly report the faults and abnormalities and inform the fault handling program to handle the abnormalities. At the same time, various alarm messages and signals will be generated in the alarm system. Whenever the alarm is generated, the alarm processing module shall send the fault message reported from BTS to the maintenance and operation terminal. The alarm will be sent to the alarm box. Visible and audible indications will be generated by the alarm box.

The alarm sent to the maintenance and operation terminal will be displayed on the screen and stored in the hard disk to be queried, processed or printed according to actual needs.

The BTS alarm functions provided by the BTS maintenance system of BSC include:

BTS communication system alarms. BTS environmental alarms. Clock system alarms. Antenna system alarms. Carrier system alarms. Baseband system alarms. Power system alarms. Transmission system alarms. Signaling system alarms. Database system alarms. Software running alarms.

6) TRX mutual-assistance management


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Faults may occur on a board running on the network. If active BCCH board becomes faulty this means an interruption in the service. That is other TRXs of the cell in normal condition can not work without BCCH. So the mutual-assistance function of the BCCH is dedicated to solve this problem.

If a certain hopping TRX in a baseband cell gets faulty, all the other baseband hopping TRXs in the cell can not work as a result. This leads to serious deterioration of the QoS in a cell, even interruption of service. To resolve this issue the baseband hopping TRX fault handling function ensures a faulty hopping TRX will not affect the normal work of other hopping TRXs.

BCCH mutual assistance during the call

In case of BCCH fault in a cell, another TRX in the cell can provide service in the place of the TRX where the original BCCH is located. At the same time, the means of fault recovery is used to restore the original TRX. If the original TRX can not be restored, service provisioning will be interrupted.

It mainly provides the following functions:

BCCH mutual-assistance during the initialization process: During cell initialization, if the configurations of the main BCCHs of the BTS or the TRXs where the main BCCHs are located can not be found, the system will search for another TRX as a assistant TRX for the main BCCH. Then it will make new configurations for the cell to ensure the normal working of the cell and support continuous mutual-assistance during cell initialization.

BCCH mutual-assistance when the cell is put to service: In case of any failure of main BCCH during normal running, the system will submit a fault state modification report to the BTS management module, which will search another available TRX as the assistant TRX for the active BCCH. And then it will reconfigure for the cell to ensure normal service provisioning in the cell. If the originally faulty BCCH is recovered during the continuous mutual-assistance process, the system will support the recovery of the original BCCH configuration according to its assigned priority. When the BCCH mutual-assistance function makes new configurations in the cell during running, the handover processes involving calls in the cell will be started first, and support the current service in the cell to make it sustain.

Avoiding close-looped mutual-assistance: To avoid the endless mutual-assistance situation, the mutual assistance process will be delayed when no TRXs available can serve as assistant TRXs. Once a certain TRX in the cell is recovered at a certain time, the BCCH mutual-assistance process will be started automatically to ensure instant service provisioning as long as there are TRXs available.

BCCH switchback: When the faulty BCCH is recovered, the user can select main BCCH immediate switchback or switchback in the case of resource check. If the user


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selects the immediate switchback, the cell will restore the configuration of the original BCCH. If the user selects switchback in the case of resource check, the TRX will serve as an ordinary TRX to participate in service provisioning in the cell.

Support of BCCH mutual-assistance of different types of cells at the same time: When the BCCH mutual-assistance function supports the baseband frequency hopping cell, RF hopping cell and non-hopping cell, and assistant TRX selection takes place, it is necessary to ensure that the non-hopping TRX is selected first and a hopping TRX is selected as second option to minimize the affected area.

Alarm prompt: In case of BCCH mutual-assistance or BCCH switchback, alarm messages and log messages will be transferred to OMC. BCCH mutual-assistance can be enabled or disabled by the user through OMC.

Baseband hopping TRX fault handling

In case of fault in a certain baseband hopping TRX during the normal running process in a cell, this BTS will report the fault. The baseband frequency hopping TRX fault handling function will delete the faulty baseband frequency hopping TRX from the corresponding frequency hopping table so that the other frequency hopping boards can work normally. At the same time, this can ensure the faulty board, which is recovered can work as a non-hopping board.

Baseband frequency hopping TRX fault handling mainly include the following functions:

Processing of baseband frequency hopping TRX faults: In case of a certain baseband hopping TRX fault during the normal running process in a cell, this BTS will report the fault. On receiving the report, the BTS management module will automatically adjust frequency hopping parameters, and delete the faulty baseband frequency hopping TRX from the corresponding hop set. Then it will make new configurations for the whole cell, the other baseband hop TRXs remain unchanged.

Recovery of the faulty TRXs: When the faulty TRX originally involved in baseband hopping, it can provide service instantly. Now the user can decide at the maintenance console if the original baseband frequency hopping configuration should be restored or they should be restored in the case of resource check. If the user selects not to restore temporarily, this TRX can provide service as a non-hopping TRX.

Maintaining the current communications in the cell: When new configurations are made for the cell in case of fault with the baseband hopping TRX or the recovery of the faulty TRX, the handover process involving the ongoing calls will be started to support the current service and make it sustain.

When fault occurs to a baseband hopping TRX or a faulty TRX recovers, the BTS will send alarm messages to the background to prompt the user that the baseband hopping TRX mutual-assistance is under way.


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The baseband hopping TRX mutual-assistance can be enabled or disabled by user through OMC.

7) Support of GPRS service

In terms of GPRS service, the BTS management module supports:

Configuration of channel attributes during dynamic PDCH<->TCH conversion

To implement real-time adjustment of the radio resources between packet switching and circuit switching according to the traffic and actual situation, the BSC provides a function of dynamic conversion between PDCH for packet switching and circuit-based TCH.

For example, when packet traffic exceeds the loading capacity of the current packet channel, the PCU needs to request packet channels from the BSC. When the circuit-based traffic load is exceeded, the BSC will request PDCHs from the PCU to use them as the TCHs to support circuit-based service.

During the dynamic conversion between channels, the BTS needs to make configurations for the BTS, and transmit messages periodically when necessary to ensure the successful configurations of channel attributes.

Reestablishment of channel connection in case of dynamic change of packet channel coding

When the quality of service of the radio channels changes, it is necessary to adjust the rate of the packet channel.

When the QoS of the packet channel is good, high-speed coding (CS-3/4) can be used on the air interface, a packet channel needs multiple 16kbps trunk links at the Abis interface, and new interworking is necessary between the BTS and BSC.

When the QoS of the packet channel deteriorates, the coding scheme for the air interface is set to CS-1/2, and the corresponding trunk links at the Abis interface are also adjusted accordingly. In these situations, the BTS needs to reestablish the channel connections and retransmit messages to the subscriber depending on the needs.

Direct message transfer between BTS and PCU

There are some messages transfer between BTS and PCU, for example when BTS reports to the PCU the supporting capability of GPRS by the TRX or when the PCU configures the cell GPRS attributes for the BTS. These messages sent by BTSM are transmitted transparently by BSC.

8) Other management processes

Other management processes mainly include circuit/channel blocking, 24/24/24 TRX networking, active/standby switchover of GMPU boards, alarm filtering, transfer of idle burst, BTS log report, and resource check.


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Channel/circuit blocking

The maintenance console supports the blocking operation on the cell, TRX, and radio channel.

The blocking process does not effect the established call. It first handover the existing call to the other traffic channel and after this handover the blocking action will be implemented so that there should be no interruption in subscriber's communication.

The cell of the best quality should be chosen for handover.

24/24/24 networking

The BTS supports the 24/24/24 networking mode, that is, a sector-cell can carry 24 TRXs, and a site can carry 72 TRXs. This will greatly expand service capacity and improve service quality.

Active/standby switchover of GMPUs

GMPU plays a critical role in the system. The fault in GMPU or the abnormality in its software can cause a failure of the whole system, so active/standby switchover is provided to ensure the system reliability. A manual active/standby switchover command can also be activated from the maintenance console. That is, the system can immediately switch the backup board to the active state.

The BSC ensures the smooth communication during the switchover, i.e., there will be no interruption in the subscribers calls. The various resources will not be suspended, and the control over the BTS can proceed normally.

Alarm filtering

In case any alarm at BTS end, the BTS will report alarm messages to the BSC, which will report them to the alarm console. Maintenance staff then can view the alarms to fix it.

If the fault is not eliminated temporarily, the function of alarm filtration can be used to avoid the repetitive issuing of this alarm. Alarm filtration of certain alarm levels, categories and boards can be achieved. The filtered alarm can be de-filtered and the alarm will resume the original reporting mechanism. It provides a flexible control on the generation and report of alarms for the ease of users.

Idle burst transfer

During network optimization, sometimes it is necessary to maximize the interference within the network to attain the maximum interference level for the network. The method is to transfer test messages through the maintenance console so that all timeslots not in the communicating state of the non-BCCH TRXs in the designated BTS in the test area will transmit the idle BURST (dummy burst).


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BTS log report

The daily internal running state of the BTS is kept in the form of log. The BSC retrieves the log information of all the sites every day, and store them in the form of file. Or the log information can be retrieved manually, starting at the BTS maintenance console.

Resource check

Resource check can be conducted at a certain time every day between the BSC and BTS to avoid the hang-up of resources due to abnormalities between the BTS and BSC. This function ensures the self-healing mechanism between the BSC and BTS i.e. reliable system functioning.

Remote maintenance of Environment Alarm Controller (EAC)

This function is responsible for remote modification of the temperature and humidity alarm threshold of the EAC, operations on the relay, and resetting of EAC. This function makes EAC better adapt to the field environment and enables EAC to automatically monitor its environment, issue alarms in the case of time-out, and drive relevant executors. In a word, it implements centralized control of the BTS.

Technical Manual M900/M1800 Base Station Controller Chapter 4 System Application

4-1

Chapter 4 System Application

4.1 Principle of System Configuration

The BSC can be configured easily and it is flexible to implement. During system configuration please follow these rules.

A multi-module BSC includes AM/CM and multiple BMs. Each AM/CM can support up to 8 BMs. Each BM has a capacity of 1024 speech channels (128 TRXs). One BSC can support 1024 TRXs, 1024 cells at the most. The 64kbit/s links between BSC and BTS should satisfy the following requirements:

Each speech channel occupies 16kbit/s and each TRX occupies two 64kbit/s links.

15:1 multiplexing is adopted for chain networking. Four RSL or OML links share one 64kbit/s channel through statistical multiplexing.

If a site is required to support CS-3, CS-4 or other higher efficient coding method, it is necessary to reserve some 64kbit/s trunk links since CS-3 and CS-4 schemes need more additional time slots. The exact amount to be reserved depends on the network planning.

In the AM/CM structure, since BM is used to implement BTS access, all 64 HWs available can be allocated to BIE. All speech channels carry through the optical fiber between BM and AM/CM. Each BM has 2 pairs of optical fibers that work in load sharing mode, total 1024 speech channels are available.

In AM/CM, FBC and GFBI are used in pairs. The quantity configured is related with the number of the BMs attached. Assuming that the quantity of BMs are N, then the quantity of FBC/GFBIs are [(N+1)/2]%2 (note: N plus 1, then divided by 2 to get an integer, and then the integer times 2 so as to ensure an even number of FBC/GFBI boards).

The number of E3M boards in AM/CM is calculated as follows: assuming that the BMs attached to an AM/CM is N, then the number of E3Ms is N % 2. The number of DRC boards is same as that of E3M boards.

In AM/CM, the number of GMCC boards depends on the number of BMs connected. The GMCC boards in slot 15 and 16 are configured fixedly. If AM/CM has 1-2 modules, just add 2 GMCC boards, if it has 3-4 modules, add 4 GMCC boards and so on. Assuming that the BMs attached to AM/CM is N, the quantity of GMCC boards are calculated by the following formula: [(N+1)/2] %2+2 (note: N plus 1, then divided by 2 to get an integer, and then the integer times 2 so as to ensure an even number of GMCC boards).

One BM provides 192 LAPD links, 8 SS7 links, and 8 PbSLs.


4-2

BIE (base station interface equipment) between BSC and BTS is configured with complete 1+1 redundancy. Two units work independently.

Up to 4 GNOD boards can be plugged in each BM, 2 GNOD boards are configured in most cases.

One BM has the resources of 64 HWs (highway) that are available for allocation. AM/CM should be configured with a clock shelf. Clock board is configured to a

stratum three clock, which is synchronous with the clock of MSC or BITS clock. The switch module synchronizes with the AM/CM clock via the optic path on the GOPT board, so it is unnecessary to configure a clock frame.

Operations and maintenance activities of the M900/M1800 BSC system are executed by the OMC (Operation & Maintenance Center). A BSC is configured with one BAM. In general, the BAM is connected to the OMC Server through network card, router, protocol conversion equipment and transmission equipment. The OMC terminals perform centralized maintenance to BSS via the Server.

TCSM units are equipped in a separate cabinet. A TCSM cabinet with full configuration contains six TCSM frames. Each TCSM frame can be configured up to 4 TCSM units. And each TCSM unit has a full configuration of one MSM board and four FTC boards.

When a TCSM unit is in full configuration and employs SS7, totally 119 speech channels can be provided.

When a TCSM unit is in full configuration but does not use SS7, 123 speech channels can be provided.

TCSM unit adopts N+1 backup mode. As there are MSM board and FTC board in TCSM unit, N+1 backup means that an additional MSM board should be configured for backup, and up to FTC boards are configured for backup according to the quantity of speech channels.

The quantity of GLAP boards is determined by the quantity of TRXs (T) and Cells (C) of each BM. If it is calculated assuming the LAPD link of 64kbit/s or 32kbit/s, the needed GLAP boards are (T+C)/32. Then, the quantity of GLAPs will be available by adding the quantity of GLAPs of each switch module. In the meantime, considering allowance, the quantity of actual configuration is the calculated total sum plus 1, and the minimum quantity of GLAPs is 2.

For multi-module BSC, the trunk E1 to the PCU is led out via the E3M board, and for single-module BSC, it is led out via the SMI board. The number of E1s is optional. One E1 can carry 128 timeslots (16Kbit/s), 4 of which are used for synchronization, and 4 for PbSL (supposing that this E1 is configured with PbSL). The number of the circuits for data transmission is 120.

4.2 Typical Configuration

Suppose:

One AM/CM takes 3 BMs, and each BM supports 64 TRXs.


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TRXs of each switching are allocated as follows: The four sites with 12 TRXs each are configured in a star network, the four sites with 2 TRXs each in a start network, and the two sites with 4 TRXs each in a chain network.

Each switching has one E1 leading to the PCU, and E1 is configured with a PbSL link.

The structure of the AM/CM is shown in Figure 4-1.

TCSM

AM/CM

E3MPCU

BMBMBM

BSC

CNET

GFBIGFBI GFBI

GOPT GOPT GOPT

Figure 4-1 Structure of AM/CM

As shown in Figure 2-1, AM/CM supports three BMs and GFBI boards employ load sharing mode, so four GFBI boards are required.

As each BM needs two E3M boards, a total of six E3M boards are required.

GMCC board works in backup mode. For three modules, four slave GMCC boards and two main GMCC boards are required. For detailed configuration, refer to Table 4-1.

Table 4-1 BSC AM/CM configuration table

No. Name Quantity 1 Transmission interface frame, FIO 1 2 Clock frame, CKB 1 3 Main control frame, MCB 1 4 GCTN 2 5 GFBI 4 6 1X2 FBC 4 7 E3M 6 8 DRC 6 9 GMCC 6 10 GSNT 2 11 Alarm board GALM 1 12 GCKS 2


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13 PWC 8

Figure 4-2 shows the networking of one BM, other two BMs have similar configurations.

BMBIE

TCSM

OpticFiber

E1

PCU

SGSN MSC

GFBI CNET

HW

E3ME1

GOPT

BIE

BIE

BIE

BIE

BTS12TRX

BTS12TRX

BTS4TRX

AM/CMBSCE1

BTS2TRX

BTS2TRX

BTS2TRX

BTS2TRX

BTS 12TRX

BTS12TRX

BTS4TRX

Figure 4-2 Networking of BM

According to the configuration, 8 BIE boards in active/standby mode are needed. In addition, each BM in multi-module BSC needs a BIE board for transparent transfer of SSN7 and PbSL signaling. So, there are 9 BIE boards in one BM.

64 TRXs require 480 (64%7.5=480) channels in the MSC direction and 16 (480/30=16) FTC boards, so 3 BMs need a total of 48 (16%3=48) FTC boards, and 12 TCSM units (4%3= 12). As TCSM unit is in N+1 backup mode, the final number of the TCSM units needed is 13 (12+1=13), and of FTC boards is 52 (48+4=52).

9 BIE boards need 5 main nodes and 2 GNOD boards.

64 TRXs and 10 sites need 74 LPAD links (64+10=74) and 2 LAPD protocol processing boards (64/2+10)/32⊄2. Since LAPD is in N+1 backup mode, 4 LAPD protocol process boards are needed.

The detailed calculated configuration data is given in Table 4-2, Table 4-3.

Table 4-2 Configuration of TCSM unit

Serial number Name Count 1 TCSM frame 4 2 PWS 8 3 FTC 52 4 MSM 13


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Table 4-3 Configuration of each BM

Serial number Name Count 1 Main control frame 1 2 BIE frame 1 4 PWC 6 5 GNET 2 6 CKV 2 7 GMPU 2 8 GEMA 1 9 GNOD 2 10 LPN7 2 11 GLAP 4 12 GALM 1 13 GMC2 2 14 GOPT 2 15 BIE 9

Technical Manual M900/M1800 Base Station Controller Appendix A Power Class

A-1

Appendix A Power Class

I. MS output power

Phase I MS output power (GSM900 and GSM1800)

Tolerance(dB) Power class GSM900 max. peak

power GSM1800 max.

peak power Normal Max. 1 20W(43dBm) 1W(30dBm) ±2 ±2.5 2 8W(39dBm) 0.25W(24dBm) ±2 ±2.5 3 5W(37dBm) ±2 ±2.5 4 2W(33dBm) ±2 ±2.5 5 0.8W(29dBm) ±2 ±2.5

Phase II MS output power (GSM900 and GSM1800)

Tolerance(dB) Power class GSM900 max. peak

power GSM1800 max. peak

power Normal Max. 1 ------ 1W(30dBm) ±2 ±2.5 2 8W(39dBm) 0.25W(24dBm) ±2 ±2.5 3 5W(37dBm) 4W(36dBm) ±2 ±2.5 4 2W(33dBm) ±2 ±2.5 5 0.8W(29dBm) ±2 ±2.5

II. BTS output power

Phase I BTS TRX power class (GSM900 and GSM1800)

GSM900 TRX power class

GSM1800 TRX power class Max. peak power Tolerance(dB)

1 320 W -0, +3 2 160 W -0, +3 3 80 W -0, +3 4 40 W -0, +3 5 1 20 W -0, +3 6 2 10 W -0, +3 7 3 5 W -0, +3 8 4 2.5 W -0, +3


A-2

Phase II BTS TRX power class (GSM900 and GSM1800)

GSM900 TRX power class GSM1800 TRX power class Max. peak power

1 320 - (<640)W

2 160 - (<320)W

3 80 - (<160)W

4 40 - (<80)W

5 1 20 - (<40)W

6 2 10 - (<20)W

7 3 5 - (<10)W

8 4 2.5 - (<5)W

Note: Since max output power are range values so no need of tolerance column.

III. Power control class

Phase I MS power control class

GSM900 GSM1800

Tolerance(dB) Tolerance (dB) Power control class

Output power (dBm) Normal Max.

Power control class


0 43 ±2 ±2.5 0 30 ±2 ±2.5 1 41 ±3 ±4 1 28 ±3 ±4 2 39 ±3 ±4 2 26 ±3 ±4 3 37 ±3 ±4 3 24 ±3 ±4 4 35 ±3 ±4 4 22 ±3 ±4 5 33 ±3 ±4 5 20 ±3 ±4 6 31 ±3 ±4 6 18 ±3 ±4 7 29 ±3 ±4 7 16 ±3 ±4 8 27 ±3 ±4 8 14 ±3 ±4 9 25 ±3 ±4 9 12 ±4 ±5 10 23 ±3 ±4 10 10 ±4 ±5 11 21 ±3 ±4 11 8 ±4 ±5 12 19 ±3 ±4 12 6 ±4 ±5 13 17 ±3 ±4 13 4 ±4 ±5 14 15 ±3 ±4 15 13 ±3 ±4

Note: When the power control class of the Phase I GSM900 MS is 0, the max. output power of the MS is 43dBm with

tolerance: !2dB (normal), !2.5dB (maximum). If the power control class is 1, the max. output power of the MS is 41dBm, with tolerance: !3dB (normal), !4dB (maximum).


A-3

Phase II MS power control class

GSM900 GSM1800

Tolerance(dB) Tolerance (dB) Power control class


Power control class


0~2 39 ±2 ±2.5 29 36 ±2 ±2.5 3 37 ±3 ±4 30 34 ±3 ±4 4 35 ±3 ±4 31 32 ±3 ±4 5 33 ±3 ±4 0 30 ±3 ±4 6 31 ±3 ±4 1 28 ±3 ±4 7 29 ±3 ±4 2 26 ±3 ±4 8 27 ±3 ±4 3 24 ±3 ±4 9 25 ±3 ±4 4 22 ±3 ±4 10 23 ±3 ±4 5 20 ±3 ±4 11 21 ±3 ±4 6 18 ±3 ±4 12 19 ±3 ±4 7 16 ±3 ±4 13 17 ±3 ±4 8 14 ±3 ±4 14 15 ±3 ±4 9 12 ±4 ±5 15 13 ±3 ±4 10 10 ±4 ±5 16 11 ±5 ±6 11 8 ±4 ±5 17 9 ±5 ±6 12 6 ±4 ±5 18 7 ±5 ±6 13 4 ±4 ±5

19~31 5 ±5 ±6 14 2 ±5 ±6 15~28 0 ±5 ±6

Note:

1) The minimum power class of GSM900 MS is 19 (5dBm), and GSM1800 MS is 15 (0dBm). 2) Power control classes 29, 30, and 31 of the GSM1800 MS apply only to call power control. When the parameter TX PWR MAX CCH is transmitted, this class is not used. If MS random access requires a power control class higher than 30dBm, then it is necessary to decode in the broadcast parameters on the BCCH. 3) At each power control class, the transmitted power of an MS is in monotonic sequence, with step length of 2 ! 1.5dB. 4) The max. time for performing MS power control class change is defined by GSM0508. After receiving power adjustment command from the SACCH, the MS will adjust itself to a new class at the rate of 2dB/60ms (13TDMA), i.e., the adjustment of 15 steps requires 900ms, starting from the first TDMA frame of the next MR cycle. If it is changed to new channel, the command for power adjustment will apply to new channels immediately.

BTS dynamic power control class 0 Pn dB 1 Pn-2 2 Pn-4 3 Pn-6 4 Pn-8 5 Pn-10 6 Pn-12


A-4

7 Pn-14 8 Pn-16 9 Pn-18 10 Pn-20 11 Pn-22 12 Pn-24 13 Pn-26 14 Pn-28 15 Pn-30

Technical Manual M900/M1800 Base Station Controller Appendix B Abbreviations

B-1

Appendix B Abbreviations

A A, Asub A-interface ACCH Associated Control Channel ACOM Antenna Combiner AGCH Access Grant Channel AM/CM Administration Module/ Communication Module APC Automatic Power Control API Application Program Interface AuC Authentication Center B BA BCCH Allocation BAM Back Administration Module BCCH Broadcast Control CHannel BER Bit Error Rate BHCA Busy Hour Call Attempts BIE Base station Interface Equipment (board) BIOS Basic Input Output System BM Basic Module BSC Base Station Controller BSIC Base transceiver Station Identity Code BSS Base Station Subsystem BSSAP Base Station Subsystem Application Part BSSGP Base Station Subsystem GPRS Protocol BSSMAP Base Station Subsystem Management Application Part BSSOMAP Base Station Subsystem Operation and Maintenance Application Part BTS Base Transceiver Station BTSM Base Transceiver Station Site Management C CA Cell Allocation CBCH Cell Broadcast Control Channel CBSM Cell Broadcast Short Message CC Calling Control CCB Call Control Block CCCH Common Control Channel CCH Control Channel CIC Circuit Identify Code CKV Clock Driver CPU Central Processing Unit CRC Cyclical Redundancy Correction CS Coding Scheme D DC Direct Current DB Database DBMS Database Management System DDN Digital Data Network DLCI Data Link Connection Identity DPC Destination Point Code DRDBMS Distributed Relational DBMS DRX Discontinuous Reception DSP Digital Signal Processor DTAP Direct Transfer Application Part DTMF Dual Tone Multi-frequency DTX Discontinuous transmission (mechanism)


B-2

E E3M E3 sub-Multiplexer EA Early Allocation EIR Equipment Identity Register EMC Electromagnetic Compatibility ETS European Telecommunication Standard ETSI European Telecommunications Standard Institute F FACCH Fast Associated Control CHannel FBC Close fiber backboard FCCH Frequency Correction CHannel FCS Frame Check Sequence FTAM File Transfer Access and manipulation G GALM Alarm board GCKS Clock board GCTN Central T Net board GEMA Emergency Message Automatic Transmission System GFBI Fiber Interface board GGSN Gateway GPRS Support Node GMC2 Module Communication 2 Link GMCC Module Communication and Control board GMCC Mobile Country Code GMEM Memory board GMPU Main Processing Unit GMSK Gaussion Filtered MSK GNET Intra-module switching network board GNOD Node control board GPRS General Packet Radio Service GSM Global System for Mobile communications GSNT Signaling switching network board GT Global Title GTP GPRS Tunneling Protocol H HC/HY COM Hybrid Combiner HDLC High level Data Link Control HLR Home Location Register HW Highway I IMEI International Mobile station Equipment Identity IMSI International Mobile Subscriber Identity IP Internet Protocol ISDN Integrated Services Digital Network ISO International Standard Organization ISR Interrupt Service ISUP ISDN User Part (of signaling system No.7) ITU International Telecommunication Union IWE Inter-Working Equipment IWF Inter-working Function L L3MM Layer-3 Mobility Management LA Location Area LAP Link Access Protocol LAPD Link Access Protocol on the D channel LAPDm Link Access Protocol on the Dm channel LAPDMAIL LAPD Mailbox LLC Logical Link Control LMT Local Maintenance Terminal LNA Low Noise Amplifier


B-3

M MA Mobile Allocation MAC Medium Access Control MAIO Mobile Allocation Index Offset MAP Mobile Application Part MCK Main ClocK board MM Mobility Management MNC Mobile Network Code MR Measurement Report MS Mobile Station MSC Mobile services Switching Center, Mobile Switching Center MSISDN Mobile Station International ISDN Number MSM MSC Subrate channel Multiplexer MT Mobile Terminal MTBF Mean Time Between Failure MTP Message Transfer Part N NE Network Equipment O OACSO Off Air Call Set up OMAP Operation and Maintenance Application Part O&M, OM Operations & Maintenance OMC Operations & Maintenance Center OMU Operations & Maintenance Unit (board) OOP Object Oriented Programming OPT Optic Interface board OS Operation System OSI Open System Interconnection P PA Power Amplifier PACCH Packet Associated Control Channel PAGCH Packet Access Grant Channel PBCCH Packet Broadcast Control Channel PbSL Pcu-bsc Signaling Link PCCCH Packet Common Control Channel PCIC Packet Circuit Identity Code PCH Paging CHannel PCM Pulse Code Modulation PCU Packet Control Unit PDCH Packet Data Channel PDN Packet Data Network PDTCH Packet Data Traffic Channel PIN Personal Identity Number PLL Phase Locked Loop PLMN Public Land Mobile Network PPCH Packet Paging Channel PRACH Packet Random Access Channel PSDN Public Switched Data Network PSTN Public Switched Telephone Network PTCCH Packet Timing advance Control Channel PTM Point To Multipoint PTM-SC Point to Multipoint Service Center PWC Power Control board R RACH Random Access Channel RF Radio Frequency RLC Radio Link Control RLM Radio Link Management RR Radio Resource RSA Rivest-Shamir-Adleman


B-4

RSL Radio Signaling Link RTE Radio Test Equipment RX Receiver/Reception RXLEV Received signal level RXQUAL Received Signal Quality S SACCH Slow Associated Control Channel SACCH/C4 Slow Associated Control Channel/SDCCH/4 SACCH/C8 Slow Associated Control Channel/SDCCH/8 SACCH/T Slow Associated Control Channel/Traffic channel SACCH/TF Slow Associated Control Channel/Traffic channel Full rate SAP Service Access Point SAPI Service Access Point Indicator SCCP Signaling Connection Control Part SCH Synchronization CHannel SDCCH Stand-alone Dedicated Control CHannel SGSN Serving GPRS Support Node SIM Subscriber Identity Module SMC Short Message Center SMI Sub-Multiplexer Interface SMS Short Message Service SMSCB Short Message Service Cell Broadcast SM-SC Short Message - Service Center SMS-GMSC Short Message Service - Gateway MSC SMS-IWMSC Short Message Service Interworking MSC SMUX Sub-Multiplexer SNDCP SubNetwork Dependent convergence Protocol SS Supplementary Service SS7 Signaling System No.7 STP Signaling Transfer Point T TA Timing Advance TBF Temporary Block Flow TC Transcoder TCH Traffic Channel TCH/F A full rate TCH TCH/F2.4 A full rate data TCH (2.4kbit/s) TCH/F4.8 A full rate date TCH (4.8kbit/s) TCH/F9.6 A full rate data TCH (9.6kbit/s) TCH/FS A full rate Speech TCH TCSM TransCoder & Sub-Multiplexer TCP Transmission Control Protocol TDMA Time Divide Multiple Access TE Terminal Equipment TEI Terminal Equipment Identifier TMSI Temporary Mobile Subscriber Identifier TN Timeslot Number TRAU Transcoding & Rate Adaptation Unit TRX Transceiver (board) TUP Telephone User Part(SS7) U UDP User Datagram Protocol Um V VAD Voice Activity Detection VEA Very Early Alloc VLR Visitor Location Register VM Voice Mailbox VSWR Voltage Standing Wave Radio

Technical Manual M900/M1800 Base Station Controller Appendix C Message Flows on Abis & Um Interfaces

C-1

Appendix C Message Flows on Abis & Um Interfaces

I. Mobile Terminated Call (MTC)


C-2

LAPDm

CHAN ACTIV ACK

DATA REQ ( AUTH REQ)

ENCR CMD (CIHP MODE CMD)

DATA IND (CIPH MODE COMP)

AUTH RPS

IMMEDIATE ASSIGN

DATA REQ (CALL PROCEED)

DATA REQ (ASSIGN CMD)

DATA IND (ASSIGN COMP)

CIPH MODE CMD

CALL PROCEEDING

CHAN ACTIV

IMM ASSIGN CMD (IMM ASSIGN)

CHAN ACTIV

CHAN ACTIV ACK

DATA REQ (ALERT)

DEACT SACCH

DATA REQ (CONNNECT)

DATA IND (CONN ACK )

CIPH MODE COMP

ASSIGN COMP

ALERTING

BSC BTS MS

CHAN REQCHAN RQD

AUTH REQ

EST IND (CM SERV REQ)

DATA IND (AUTH RPS )

DATA IND (SETUP)

RF CHAN REL

RF CHAN REL ACK

ASSIGN CMD

CONNECT

UA

A- bis Interface Um Interface

Two-way Communication

CONNECT ACK

SABM (CM SERVICE REQ)

UA

SETUP

SABM

REL CONF

REL REQ

LAPDmEST IND

RACH

SDCCH

AGCH

TCH/FACCH


C-3

II. Mobile Originated Call (MOC)

LAPDm

CHAN ACTIV ACK

DATA REQ ( AUTH REQ)

ENCR CMD (CIHP MODE CMD)

DATA IND (CIPH MODE COMP)

AUTH RPS

IMMEDIATE ASSIGN

DATA REQ (CALL PROCEED)

DATA REQ (ASSIGN CMD)

DATA IND (ASSIGN COMP)

CIPH MODE CMD

CALL PROCEEDING

CHAN ACTIV

IMM ASSIGN CMD (IMM ASSIGN)

CHAN ACTIV

CHAN ACTIV ACK

DATA REQ (ALERT)

DEACT SACCH

DATA REQ (CONNNECT)

DATA IND (CONN ACK )

CIPH MODE COMP

ASSIGN COMP

ALERTING

BSC BTS MS

CHAN REQCHAN RQD

AUTH REQ

EST IND (CM SERV REQ)

DATA IND (AUTH RPS )

DATA IND (SETUP)

RF CHAN REL

RF CHAN REL ACK

ASSIGN CMD

CONNECT

UA



CONNECT ACK

SABM (CM SERVICE REQ)

UA

SETUP

SABM

REL CONF

REL REQ

LAPDmEST IND

RACH

SDCCH

AGCH

TCH/FACCH


C-4

III. Calling Party Release

DATA REQ (RELEASE)

DATA IND (DISCONNECT)

DISC

UA

BSC BTS MS (Caller)

DATA REQ (CHAN REL)

RELEASE COMPLETE

RELEASE


DISCONNECT

DATA IND ( RELEASE COMP)

REL IND

RF CHAN REL

RF CHAN REL ACK

DEACT SACCH

CHAN RELEASE


LAPDm


C-5

IV. Called Party Release

BSC BTS MS(Caller)

DATA REQ (CHAN REL)

RELEASE

RELEASE COMP


DISCONNECTDATA REQ (DISCONNECT)

REL IND

RF CHAN REL

RF CHAN REL ACK

DEACT SACCH

DATA IND (RELEASE)

DISC

CHAN RELEASE

UA

DATA REQ (RELEASE COMP)


LAPDm

Technical Manual M900/M1800 Base Station Controller Appendix D LAPD and LAPDm Functionality

D-1

Appendix D LAPD and LAPDm Functionality

I. LAPD functionality

Establishes one or several data links on the D channel.

Delimits, locates and transmits transparently frames so that a string of bits transmitted on the D channel in the form of frames can be identified.

Implements sequence control to keep the order of the frames that pass the data link connections.

Checks the transmission errors, format errors and operation errors in the data link connections.

Makes recovery based on the detected transmission errors, format errors and operation errors.

Notifies the management layer entities of the unrecoverable errors.

Flow control.

II. LAPDm functionality

Establishes on the Dm channel one or several data link connections (DLC), which are differentiated with Data Link Connection Identifiers.

Allows for frame type identification.

Allows L3 message units to be transmitted transparently between L3s.

Exercises sequence control to maintain the order of frames that pass DLC.

Check on the format and operation errors on the data links.

Flow control.

Establishes a data link when there is an access request from RACH (seizure determination).

Technical Manual M900/M1800 Base Station Controller Appendix E Message Flows on the A-interface

E-1

Appendix E Message Flows on the A-interface

This chapter describes the message flows of location update, calling and inter-BSC handover in the same MSC on the A-interface.

Note:

1) The "Authentication Request" and "Authentication Response" in the flow are optional. 2) The order of the "TMSI Re-allocation Complete" message is changeable.


E-2

I. Location Update

BSS MSC

CR Complete L3 Message (Location Update Request)

CC: Connection Verification

Authentication Request

Authentication Response

DT1: Cipher Mode Command

DT1: Cipher Mode Complete

DT1: Location Update Accepted

DT1: TMSI Reallocation Complete

DT1: Clear Command

DT1: Clear Complete

II. Mobile Originated Call (MS-PSTN)


E-3

BSS MSC

CR: Complete L3 Message (CM Service Request)

CC: Connection Confirm

Authentication Request

Authentication Response

CM: Service Accepted

DT1: Cipher Mode Command


DT1: Setup

DT1: Call Process

DT1: Assignment Request

DT1: Assignment Complete

DT1: Warning

DT1: Connection

DT1: Connection Confirm

Talking

DT1: Release

DT1: Clear Complete

RLSD

RLC

DT1: Clear Command

DT1: Release Complete

III. Mobile Originated Call (MS-MS)


E-4

BSS MSC BSS

CR: Complete L3 Message (CM Service Request)

CC: Connection ConfirmDT1: Authentication RequestDT1: Authentication ResponseDT1: Cipher Mode Command

DT1: Setup UDT: Paging

CR: Paging ResponseDT1: Call Process

DT1: Assignment Request

CC DT1: Authentication Request

DT1: Authentication Response

DT1: CipherDT1: Cipher CompleteDT1: SetupDT1: Call ConfirmDT1: Assignment RequestDT1: Assignment CompleteDT1: Warning

DT1: WarningDT1: Connect

DT1: Disconnect DT1: Connection ConfirmDT1: Connection Confirm

Talking .DT1: Disconnect

DT1: DisconnectDT1: Release

DT1: ReleaseDT1: Release CompleteDT1: Clear Command DT1: Release Complete

DT1: Clear CommandDT1: Clear Complete RLSD DT1: Clear Complete

RLSD RLC

RLC


DT1: Assignment Complete

..

IV. Inter-BSS Handover in the Same MSC


E-5

BSS MSC BSS

DT1: Handover Request CR: Handover Request

DT1: Handover Request Confirm

DT1: Handover Command

DT1: Handover Detected

DT1: Handover Complete

DT1: Clear Command

DT1: Clear Complete

RLSD

RLC

Documents

BSC Technical Manual