02 Hardware Architecture

8/12/2019 02 Hardware Architecture

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User ManualM900/M1800 Base Transceiver Station (BTS30) Table of Contents

Huawei Technologies Proprietary

i

Table of Contents

Chapter 2 Hardware Architecture ................................................................................................ 2-1

2.1 Overview............................................................................................................................ 2-1

2.2 CDU Frame........................................................................................................................ 2-2

2.2.1 CDU......................................................................................................................... 2-2

2.2.2 ECDU ...................................................................................................................... 2-3

2.2.3 EDU......................................................................................................................... 2-3

2.2.4 RCDU ...................................................................................................................... 2-5

2.2.5 REDU ...................................................................................................................... 2-5

2.2.6 SCU......................................................................................................................... 2-5

2.2.7 ESCU ...................................................................................................................... 2-6

2.3 TRX Frame ........................................................................................................................ 2-6

2.3.1 TRX ......................................................................................................................... 2-6

2.3.2 PBU ....................................................................................................................... 2-11

2.4 Common Resource Frame .............................................................................................. 2-12

2.4.1 PSU ....................................................................................................................... 2-12

2.4.2 PMU ...................................................................................................................... 2-13

2.4.3 TMU....................................................................................................................... 2-14

2.4.4 TES ....................................................................................................................... 2-17

2.4.5 ASU board............................................................................................................. 2-19

2.4.6 ABB ....................................................................................................................... 2-20

2.4.7 ABA ....................................................................................................................... 2-21

2.5 Other Parts of the Cabinet ............................................................................................... 2-21

2.5.1 TDU ....................................................................................................................... 2-21

2.5.2 FMU....................................................................................................................... 2-27

2.5.3 Switch Box............................................................................................................. 2-27

2.5.4 Fan Box ................................................................................................................. 2-28

2.5.5 Air Box................................................................................................................... 2-28

2.6 Antenna and Feeder System........................................................................................... 2-28

2.6.1 Antenna................................................................................................................. 2-29

2.6.2 Feeder................................................................................................................... 2-30

2.6.3 Lightning Arrester.................................................................................................. 2-30

2.6.4 Tower-top Amplifier (Optional) .............................................................................. 2-31

2.7 Power Supply System...................................................................................................... 2-32

2.7.1 Overview ............................................................................................................... 2-32

2.7.2 Overall Structure ................................................................................................... 2-33

2.8 Environment Monitoring System...................................................................................... 2-35

2.8.1 Outlook of Environment Monitoring Instrument..................................................... 2-35


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User ManualM900/M1800 Base Transceiver Station (BTS30) Table of Contents


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2.8.2 Function Provided by Environment Monitoring Instrument ................................... 2-36

2.8.3 Environment Monitoring Instrument Inputs ........................................................... 2-36

2.8.4 Alarm Indicators .................................................................................................... 2-37

2.8.5 Executing Devices................................................................................................. 2-37

2.8.6 Communication ..................................................................................................... 2-38

2.9 Lightning Protection System............................................................................................ 2-38

2.9.1 Lightning Protection for DC Power Supply............................................................ 2-39

2.9.2 Lightning Protection for AC Power Supply............................................................ 2-40

2.9.3 Lightning Protection for Trunk Cables................................................................... 2-41


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User ManualM900/M1800 Base Transceiver Station (BTS30) Chapter 2 Hardware Architecture


2-1

Chapter 2 Hardware Architecture

2.1 Overview

A BTS30 cabinet mainly comprises a common resource frame, a TRX frame and a

CDU frame, which can be flexibly configured according to the user demands. There

are also some other elements like TDU, switch box, fan box, air box, etc.

The hardware architecture of the BTS30 cabinet is shown in Figure 2-1 .

CDU CDU CDU

SWITCH BOX

TX

RX

TRX

TX

RX

TRX

TX

RX

TRX

TX

RX

TRX

TX

RX

TRX

TX

RX

TRX

P

S

U

P

S

U

P

S

U

P

S

U

P

M

U

T

M

U

T

M

U

T

U

E

T

E

S

AIR BOX

FAN BOX

TDU

CDU: Combiner and Divider Unit TRX: Transceiver UnitPMU: Power Monitoring Unit TMU: Timing/Transmission and Management UnitPSU: Power Supply Unit TES: Transmission Extension Power Supply UnitTEU: Transmission Extension Unit TDU: Timing Distribution Unit

Figure 2-1Hardware architecture of the BTS30 cabinet


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2-2

2.2 CDU Frame

The CDU frame implements the combining of transmitted signals, dividing of

received signals and duplex functions. The frame can be configured with CDU,ECDU, EDU, RCDU, REDU, SCU or ESCU.

2.2.1 CDU

I. General

CDU combines and filters the transmitted signals, filters, amplifies and distributes

received signals. It also provides feed circuit for the tower-top amplifier through a

bias-T circuit.

Through bridge combing (broadband combing) used in BTS30, multiple TX and RX

signals can be multiplexed on a single antenna unit.

The 2 channels of transmitting signals are combined into 1 (2-into-1), while at the

receiving end signals from 1 of the 2 channels are divided into 4 (or 8 incase of only

one channel) channels.

CDU supports the P-GSM band (GSM900 and GSM1800), and the maximum input

power of its single port is 60 W.

II. Structure and function

The functional blocks of the CDU are shown in Figure 2-2 .

Test coupler Amp. feeder

Divider

Duplexer

LNA Rx filter

Alarm and control unit

Combiner Tx signal input

Rx signal output

Divider

Rx signal output

LNA

Amp. feeder

CDU

Figure 2-2Functional blocks of the CDU

Besides the combining and dividing functions, CDU also has the following alarm

detection functions:

VSWR (Voltage Standing Wave Ratio) monitoring: Monitoring the status of

antenna system. When the detected VSWR exceeds the threshold 1.5:1, the


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2-3

CDU reports minor alarm and the corresponding indicator on the panel is on.

When the VSWR exceeds the threshold 2.5:1, the CDU reports critical alarm,

the corresponding indicator on the panel is on, and signal transmission will stop

1 minute later.Low noise amplifier fault alarm: The fault signal is extracted from the power

supply current of the low noise amplifier. When the current exceeds a certain

level, alarm signals and indications are generated.

Tower-top amplifier alarm: When there is tower-top amplifier in service, the

CDU determines the operation status of the amplifier according to its working

current. If the current exceeds preset value or there is no current, alarm signal

will be generated.

Control functions: Remotely control the low noise amplifier attenuation

(dynamic control 15 levels, in steps of 1dB) both in the main receiving path and

diversity receiving path, supply/cut the feeder depends on whether tower-topamplifier is equipped, cut the feeder to the amplifier in case of alarm.

Note:

The input power of the CDU configured in BTS30 is 60W. When PBU is used, ECDU with large powershould be configured.

2.2.2 ECDU

The functions and external interfaces (including dimensions) of ECDU are the same

as that of CDU. It implements combination of transmitted signals, dividing of

received signals, and duplex functions. The difference is that the maximum power

input of the single port of ECDU reaches 100W.

2.2.3 EDU

I. General

EDU is a low-loss duplex and dividing unit aimed to solve the issue of wide

coverage. It can perform the duplex function for two TRXs, the filtering of

transmitted/received signals, low noise amplification, and dividing function. It also

provides feeder to the tower-top amplifier.

Each TRX uses its own antenna, so no combination of signals is needed. For

received signals, 1-to-2 dividing is employed.


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2-4

EDU supports the P-GSM band (GSM900 and GSM1800), and the maximum input

power of its single port is 60 W.


The functional blocks of the EDU are shown in Figure 2-3 .

EDUTest coupler Amp. feeder

Divider

Duplexer

LNA

Alarm and control unit

Tx signal input

Rx signal output

Divider Rx signal output

LNA

Amp. feeder Tx signal input Duplexer Test coupler

Figure 2-3Functional blocks of the EDU

Besides the combining and dividing functions, the EDU also provides the following

alarm detection functions:

1) VSWR (Voltage Standing Wave Ratio) monitoring: Monitoring the status of the

antenna system. When the VSWR exceeds the threshold 2.5:1, the EDU reports

alarm.

2) Low noise amplifier fault alarm: The status of the LNA can be determined based

on the power supply current. When the current exceeds a certain level, alarm

signals and indications are generated.

3) Tower-top amplifier alarm: When there is tower-top amplifier in service, EDU

determines the operation status of the amplifier according to the working current of

amplifier. If the current exceeds preset value or there is no current, alarm signal will

be generated.

4) Control functions: Remotely control the low noise amplifier attenuation (dynamic

control 15 levels, in steps of 1dB) both in the main receiving path and diversity

receiving path, supply/cut feeder depends on whether tower-top amplifier is

equipped, cut the feeder to the amplifier in case of alarm.


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2-5

2.2.4 RCDU

RCDU is the same as ECDU in structure, functions, peripheral interfaces, peripheral

interface dimension and maximum input power. It can also combine transmitted RFsignals, divide received RF signals and implement reception and transmission

duplex. The difference between RCDU and ECDU lies in the bands supported by

them. The band supported by RCDU ranges from 876 to 901 MHz (uplink) and 921

to 946 MHz (downlink). For the BTS working in the EGSM band with the frequency

range of 880-890 MHz (uplink) and 925-935 MHz (downlink), RCDU is optional.

2.2.5 REDU

REDU is the same as EDU in structure, functions, peripheral interfaces, peripheral

interface dimension and maximum input power. It can also implement 1-to-2 divisionof received signals and implement reception and transmission duplex. The

difference between REDU and EDU lies in the bands supported by them. The band

supported by REDU ranges from 876 to 901 MHz (uplink) and 921 to 946 MHz

(downlink). If the BTS works in the EGSM band with the frequency range as

880-890 MHz (uplink) and 925-935 MHz (downlink) and it is required to achieve low

loss, REDU is optional.

2.2.6 SCU

I. General

SCU combines the signals from 4 TRXs into 1 channel for transmission. It employs

the electric bridge with 3dB power loss to achieve the broadband combing. Used

together with CDU, it can achieve the combination of signals from multiple TRXs.

The introduction of SCU is to reduce the number of CDUs, hence saving costs.

SCU supports the PGSM band (GSM900 and GSM1800), and the maximum input

power of its single port 60 W.


The functional blocks of the SCU are shown in Figure 2-4 .


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2-6

SCU1

2

3

4

Combiner

Tx signal input

Combiner

Tx signal outputCombiner

Figure 2-4Functional blocks of the SCU

2.2.7 ESCU

ESCU is the same as SCU in structure, functions, peripheral interfaces and

peripheral interface dimension. It can also implement 4-in-1 combination of

transmitted signals. The differences between ESCU and SCU lie in:

Bands supported by them. The band supported by ESCU ranges from 921 to

960 MHz (900M ESCU) and 1805 to 1880 MHz (1800M ESCU).

Maximum input power supported by their single port. The single port of ESCU

supports the maximum input power of 100 W.

The 900M ESCU can be used with 900M CDU, ECDU, EDU, RCDU and REDU

while the 1800M ESCU can be used with 1800M CDU, ECDU and EDU. When

ESCU works with the cooperation of ECDU, it can implement more than four

carriers, which thus improves the BTS transmit power and effective radiated power

of antenna ports and enlarges the coverage of BTS.

2.3 TRX Frame

The TRX frame implements all the processing functions of the carrier, including

baseband processing, RF processing, power amplifier and power supply. The TRX

frame can be configured with the TRX and the PBU.

2.3.1 TRX

I. General

TRX is the key part of the BTS which receives various types of management and

configuration information issued by the TMU and reports its status and alarm

information to the TMU.


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2-7

The TRX separates the received information from the mobile stations through

demodulation and balancing into signaling and speech information, and transmits

them upward (i.e. to BSC and MSC). The downlink signaling and speech information

is sent to the CDU and the antenna after being processed by the TRX.TRX has two types: 40W TRX and 60W TRX.

II. Structure and functions

The structures of the two types of TRXs are mainly the same. Figure 2-5 shows the

structure of the 40W TRX. It includes the baseband signal processing unit and the

radio frequency signal processing unit.

SCP DSP CUITDP PAU

RCU

TBU RPU

DBUS FH_BUS

CBUS

TIMING_BUS

Clock processing part

Send

Main receiver Diversity receiver

SCP: Signaling Processing Unit DSP: Digital Signal Processing UnitCUI: Carrier Unit Interface PAU: Power Amplifier UnitRCU: Receiving Unit TDP: Transmitter Driver and PLL unitTBPU: TRX Baseband signal Processing Unit RPU: RF signal Processing UnitCBUS: Control Bus FH_BUS: Frequency Hopping BusDBUS: Data Bus

Figure 2-5Structure of the 40W TRX unit

1) Baseband signal processing unit

The baseband signal processing unit of 40W TRX is called TBPU (Transceiver

Baseband Process Unit), while that of 60W TRX is called HTBU (High Power TRX

Baseband Processing Unit). The unit consists mainly of the Signaling Processing

Unit (SCP), the Digital Signal Processing unit (DSP), and the Carrier Unit Interface

(CUI). As the GSM system is a time division multiplexing system, the operation of

the TRX relies on various clocks. So the TRX contains some clock processing

logical units.

Signaling processing unit (SCP)


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2-8

The SCP processes signaling protocols on different BTS interfaces, including the

layer 2 protocol LAPDm with the mobile station (MS), the layer 2 protocol LAPD with

the BSC interface, and the layer 2 protocol (DCL) with the operation & maintenance

module (OMU), as well as layer 3 non-transparent messages.The SCP also handles DSP program loading and alarm processing of the whole

TRX module.

Digital signal processing unit (DSP)

The DSP performs such functions as signal encoding/decoding, signal demodulation,

interleaving and de-interleaving, and speech/data communication with the TRAU.

It sends the signaling received from the MS to the SCP, receives signaling sent from

the SCP, and performs corresponding encoding/decoding according to related

protocols. It sends the downlink data via the CUI to the carrier unit RPU.

Carrier unit interface (CUI)

The CUI is the interface between the DSP and the RPU. It supports baseband

hopping, and according to system configuration can work in either hopping or

non-hopping mode (when the system works in the RF hopping mode, the hopping

interface works in non-hopping mode and the hopping functions are completed by

the carrier unit).

The CUI samples and filters the uplink intermediate frequency signals sent from the

RPU, and sends them to the DSP for demodulation and combination.

Clock processing part

T he TRX extracts clocks sent from the TMU over the clock buses. To ensure the

reliability, the clock buses work in active/standby mode. These clocks include the

frame clock, the octet bit clock, and the frame number.

The clock processing part in the TRX first chooses either the active clock or the

standby clock, then makes frequency division calculation and generates the timeslot

number and bit clocks required by the local TRX.

2) Radio frequency signal processing unit (RPU)

The RPU consists of 3 parts: Receiving Unit (RCU), Transmitter Driver and PLL unit

(TDP), and Power Amplification Unit (PAU).

Receiving unit (RCU)

The RCU provides diversity reception functions, that is, the receiver consists of two

completely independent channels, and the input signals come from the main

antenna and diversity antenna. In complicated radio transmission areas where one

antenna receives very poor signal, the signal received from the other (diversity)

antenna may be of a better quality.


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2-10

frequency conversion, then sends them to the receiver after coupling. It is used to

check the TRX transmit channel and the receive channel.

Power amplifier unit (PAU)

The PAU mainly performs radio signal amplification. The standard output power of

40W 900M TRX, 40W 1800M TRX and 60W TRX is respectively 46.0dBm, 45.5dBm

and 47.3dBm. It also provides feed sampling signals controlled by the transmitter

APC, and the following alarm information:

Over-temperature alarm, when the temperature of the power amplifier exceeds

85 C, the power amplifier unit reports the high-temperature alarm via the

baseband unit, and automatically turns off the power amplifier.

Over standing wave alarm, when the standing wave at the power amplifier

output end exceeds 3.5, it reports standing wave alarm to the baseband unit.

III. Interface

External interfaces of the TRX module includes:

CBUS2: the interface between the TRX and the TMU. The TMU performs

management and maintenance on the TRX module through the CBUS.

DBUS1, DBUS2: the switching functions of TMU switch the DBUS of the TRX to the

Abis interface. The uplink and downlink signaling processed by the SCP and the

uplink and downlink speech data processed by the DSP are all transmitted through

the DBUS.

TIMING_BUS: it receives the frame clock and 1/8-bit clock as well as frame number

of the TDU, and obtains the various clock signals required by the TBU board

through the clock unit interface.

FH_BUS: used to transmit hopping data between TRX modules when the BTS is in

the baseband hopping mode.

Radio interface: the TRX radio interface has 1 transmit terminal and 2 receive

terminals. The function of the 2 receive terminals is the main reception and diversity

reception. The TRX radio interfaces are connected to the CDU.

Panel display: on the panel, there are 4 LED indicators, from top to bottom they are

power supply indicator, SCP running indicator, DSP running indicator, and fault

indicator.


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2.3.2 PBU

I. General

The Power Booster Unit (PBU) is a kind of TRX output power amplifier aimed to

solve the problem of wide coverage. It can enhance the Effective Radiation Power

(ERP) of the antenna and enlarge the coverage area of a BTS. The maximum

output power of the PBU reaches 49 1dBm.

The PBU comprises the power synthesizer module, the alarm management module

and the power supply module. It can amplify the output power of 1 TRX.

II. Structure and functions

The functional blocks of the PBU are shown in Figure 2-6 .

Input coupling & delay filtering

Amp. & phase control 60W power amplify

Power Synthesizer Module

Alarm collect & outputControl signal generation

Alarm Management Module

26V

26V

8V

8V

Alarm collectionPower amplify control

Alarm output

26V

TRXpoweroutput

PBU

CoupleOutput

PBUpower output

P o w e r m o d u l e

P o w e r s y n t

h e s i z e

a n d

d e t e c t

Figure 2-6Functional blocks of PBU

The PBU couples the 40W power signals output from the TRX into main channel

signals and coupled channel signals. The main channel signals, after delay filtering,

enter the power synthesizer unit. The coupled channel signals are amplified into

60W signals before being sent to the power synthesizer unit. To obtain final

combined signals, amplitude and phase control will be conducted on the 2 channels

of input signals.

The generation of control signals and the collecting/reporting of alarms are

completed by the alarm management module. While the coupling, controlling and

synthesizing of power signals are performed by the power synthesizer module.

1) Power synthesizer module


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Under the control of alarm management module, the power synthesizer module

amplifies TRX output signals, and at the same time provides power control and

alarm information, and alarm signals to the alarm management module, which

detects power amplification functionality and reports alarms.2) Alarm management module

The alarm management module receives from the power synthesizer module the

power control and alarm information, and alarm signals. It is responsible for the

detection of power amplification functionality and the control over amplitude and

phase. It also reports relevant alarms.

3) Power supply module

The power supply module supplies power to the power synthesizer module and the

alarm management module.

2.4 Common Resource Frame

The common resource frame is the most import part of the cabinet. It includes 14

slots. Except for slots No.8 and No.9 which are reserved, other slots are respectively

configured (from left to right) with PSUs (6 slots), PMU, TMU, TES and TEU.

Configurations of the TES and the TEU are optional.

2.4.1 PSU

PSU is a built in power supply module.

Depending on the power supply mode, BTS30 uses the power supply module of

different models. When 220VAC is adopted, the BTS uses the power supply module

with 220VAC input and +26VDC output. When +48VDC is adopted, it uses the

module with +48VDC input and +26VDC output. When +24VDC is used, no power

supply module is needed.

One PCU can supply power to two TRXs (or PBUs) in N+1 flow-equalization

hot-standby mode. The working current of the module is 25A.

Note:

For detailed descriptions, please refer to section 2.7 Power Supply System.


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2.4.2 PMU

I. General

PMU (Power Monitoring Unit) is close to the power supply module, managing the

power supply of the module. There are two types of PMUs: PMU for the DC/DC

module and PMU for the AC/DC module. The main difference between these two is

the battery management function. To reduce work load, both the AC/DC module and

the DC/DC module share one monitoring board.

II. Functions

Following describes the AC/DC module monitoring board.

1) ControlSwitch on/off of the power module (remote control available), with an output

signal of 12V/10mA

Floating/equalizing charge of battery and current limit control

Connect/disconnect control of battery protection load, with a 230.5V output

low-voltage alarm, loading power-on/off condition

2) Switch signals

AC mains on/off signal and high-/low-voltage signal (12V/10mA)

Four fault status parameters (12V/10mA) provided to the monitoring board by 4

AC/DC modules

Fan monitoring status parameters (normally, 12V/10mA)

Fuse on/off status parameters of external battery (-0.3V


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2-14

Fan PMU

AC power supply

AC/DC AC/DC ... AC/DC

Fuse

Battery

L o a d

Figure 2-7Illustration of the PMU monitoring

2.4.3 TMU

I. General

TMU is located in the common frame of the BTS30. It is the timing, transmission and

management function entity of BTS30. It has the following main functions:

Provides channel multiplexing and flexible networking modes (including star-,

tree-, and chain- connections).

Provides Man-Machine Interfaces (MMI) and operation & maintenance links for

software loading, fault management, configuration management, performance

management and security management, etc.

Provides centralized BTS clock and its management, and clock hot standby

function.

Provides alarm signal input ports, and handles external alarm collection and

control.

Two TMUs can be configured in the basic cabinet, providing clock source in hotstandby mode and serving to increase the number of E1 interfaces (each TMU

provides 4 E1 interfaces). In combined cabinet configurations, TMU boards are

configured in the basic cabinet only.

II. Structure and working principle

The functional blocks of the TMU are shown in Figure 2-8 .


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2-15

MCK

OMU

BIU

EAC

DBUS

CBUSMMI

BSC

MCK

Act ive TMU

Environment Monitors

Abis

TDU

Standby TMU

BIU

TBUS

Maintenance Terminal

RS485

External clock

BSC: Base Station Control TMU: Timing/Transmission and Management UnitBIU: Base Station Interface Unit OMU: Operation and Maintenance UnitEAC: External Alarm Collector MCK: Main Clock moduleTBUS: Timing Bus DBUS Data BusCBUS: Control Bus TDU: Timing Distribution Unit

Figure 2-8Functional blocks of the TMU

1) Base station interface unit (BIU)

The BIU handles conversion and reconversion between digital signals of the BTS

internal HWs and the HDB3 codes (on E1 lines). It switches timeslots on HW toachieve flexible timeslot configuration, extracts superior clock signals, supports

external clock input, and outputs accurate clock signals through phase locking and

frequency division. It synchronizes internal bus data transmission, or generates

free-run clock signals when superior clocks are not available (due to E1 line or BSC

fault) to synchronize internal bus data transmission, and generates alarm and

reports them to OMU.

One BIU module can support a maximum of 4 E1 lines. The BIU modules on the two

TMU boards in one cabinet can be mutually extended, and the data on the 8

mutually extended E1 lines can be freely switched. The E1 interfaces on the BIUmodule can be respectively connected to the BSC or to the higher/lower level BTS

to complete star, tree, and chain connections.

2) Operation and maintenance unit (OMU)

The OMU module is the core control and processing center of the TMU. Through the

OMU, performance parameters of various BIU and MCK units can be directly

configured.

The OMU receives fault alarms, handles fault management, and communicates via

internal control buses with the CPU of various units (TRX, CDU, PMU, TES, etc.) in

the BTS, so as to complete the operation and maintenance of the whole system.


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It collectively loads and saves the software of various BTS units before loading

software for each unit according to demands. Moreover, it supports the

Man-Machine Interface (MMI) connecting to the PC.

The Flash memory of the OMU module can store two different versions of BTSsoftware. One is the software currently used by the BTS and the other one is the

previous BTS software. It can load either version according to the requirements to

each board.

When the software on the BTS needs to be upgraded, the new version can be

loaded from the BSC through OML and saved on the OMU to replace the old

version. Meanwhile, the OMU keeps the original software version of the BTS as a

backup, in case the loading should fail.

3) Main clock module (MCK)

The MCK is configured with an OCXO (oven controlled crystal oscillator) compliant

with the stratum 3 A standard, and phase-locking and frequency-division circuits.

According to system configuration, the MCK can work in the free-run mode or

software phase-locked mode to output a reference clock SREF with a stability better

than 5x10 -8. Moreover, it can provide the frame clock FCLK used by radio interfaces,

the octet bit clock OBCLK, and the frame number (FN).

The clock source of a synchronous cell is provided by the MCKs on the two TMU

boards in the basic cabinet of the basic cabinet group. The MCK modules on the two

boards work in hot standby mode. Switchover is made automatically in case ofactive board failure, which will be reported to the OMU.

4) External alarm collector (EAC)

The EAC collects the alarm signals from environment monitors, including 8 inputs of

digital signals for fire, smog, (high/low) temperature, humidity, water, BTS room door

control (open/closed), cabinet door control (open/closed), and air-conditioning

alarms. For expansion, the EAC also reserves 16 input channels for digital signals, 8

input channels for analog signals and 8 output channels for digital signals. The

collected alarm signals are reported to the OMU.

III. Interfaces

Abis interface: One TMU provides 4 E1 interfaces. two TMU boards can provide up

to 8 E1 interfaces for connection with the BSC or other BTS (corresponding to

different configuration modes of the BTS).

Internal data bus DBUS: provides two 32-timeslot TDMA buses (i.e. DBUS1 and

DBUS2) and corresponding clock signals, connecting the TRXs of one cabinet

group, and transmitting traffic and signaling data of TRXs. When there are less than

10 TRXs in one cabinet group, 2 buses can work in the active/standby mode.


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Internal control bus CBUS: The communication between TMUs is implemented

through CBUS1, and that between TMU and TRX is implemented through CBUS2.

CBUS3 is responsible for the communication between TMU and low-rate control

parts like CDU, PMU and TES, and between TMU and external monitors. For details,refer to Figure 2-8.

Internal clock bus TIMING_BUS: provides clocks (frame synchronization clock

FCLK, octet bit clock OBCLK) and frame No. (FN) required by radio interfaces for all

TRXs in the synchronous cell, and the highly accurate reference clock SREF for the

radio frequency processing unit.

Alarm input interface EAC: provides 24 digital signal inputs, 8 analog signal inputs

and 8 digital signal outputs. Among them, the 8 digital signal inputs are external

environment alarm inputs, while the remaining 16 digital signal inputs, 8 analog

signal inputs and 8 digital signal outputs are reserved for user extension.

Man machine interface: a standard asynchronous serial port or network port, it

completes the communication with PC, enabling the operation personnel to perform

various operations locally.

External synchronization clock interface: inputs highly accurate 2MHz clock

compliant with G.703 wave forms, which is used as the frequency reference of E1

and system data buses.

2.4.4 TES

TES provides TEU with various types of working power supplies and handles

communication transfer. It provides +5V and -5V power and ringing current, so that

TEU board can work normally to perform transmission network functions, thus

realizing base station built-in transmission.

TES can communicate with TEU and TMU to achieve information reporting from

TEU to TMU.

I. Functions

The TES board has the main functions as follows:

Provides the transmission board with DC power supply, including +5V and -5V.

Achieves the communication between TMU and TEU.

Provides transmission board with ring current, the ringing current signal is the

75V/25Hz sine wave AC signals.

II. Structure

The structure of the TES unit is shown in Figure 2-9 .


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2-18

Communicationmodule

Power supply

module

+26V input1st +5V output

Ringing current output-5V output

To the 1st TEU

To the 2nd TEU

To two TEUs simultaneously

To TEU communication serial port

To TMU communication serial port

2nd +5V output

To two TEUs simultaneously

Figure 2-9TES structure

Power supply module

The power supply module of the TES board includes two parts, the DC/DC

conversion circuit and the DC/AC conversion circuit. The DC/DC conversion circuit

converts two +24V DC supplies into +5V DC and one +24V DC supply into 5V DC.

The DC/AC conversion circuit converts +24V DC into 75V AC ringing current.

The ringing current module is featured by high performance ringing current signal

sources, sine wave output, low distortion, light weight, and high power density. Its

output voltage is 75V AC, and its output current is 40mA, with a standard tone of

25Hz.

Note:

Figure 2-9 shows that TES can provide power for 2 TEU boards.

Communication module

The main function of the communication module is to handle the communication

between TES and TMU, between TES and TEU, and to acquire the PCB version No.

and cabinet No. of the TES board.

The serial port communication between TES and TMU is implemented through

RS485 standard. TES is connected with CBUS3 via the level conversion circuit. The

serial port communication between TES and TEU adopts the point-to-point mode,

with the serial port level as the TTL level.

Communication with TMU mainly includes reporting transmission network

information and transmission board information from TEU to TMU, as well as

reporting TES board status information to TMU.


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Communication with TEU is mainly to acquire transmission network and base

station transmission board information.

2.4.5 ASU board

Due to the complexity of network, the base station is required to support multiple

external interfaces and flexible networking modes.

Besides the E1 interfaces, the BTS30 also has the built-in transmission system. It

supports the 155M SDH optical interfaces. All these interfaces are provided by ASU.

The built-in transmission system makes product networking more flexible and saves

user's investment on transmission equipment.

ASU board is used in SDH transmission networks.

1) Basic features

ASU uses Huawei-developed ASIC transmission chips, so the system has an high

performance/price ratio and stability. One board integrates all the functions of

standard SDH transmission equipment including double STM-1 optical interfaces, 8

E1 electrical interfaces, full cross capabilities, 3 necessary clock phase-lock working

modes, order wire, RS232 transparent transmission serial ports, and Ethernet

interfaces.

The ASU board provides 4 E1 interfaces with re-timing functions. When users want

to use this function (e.g., in the case when GSM and DDN have very highrequirements on clock precision), this can be set through network management.

Meanwhile, in application cases such as the GSM base station and private networks,

the user can be provided with 64kbit/s sub-rate cross functions between the first 4

E1 so that maximum utilization of transmission resources are achieved.

2) Functions

The ASU SDH optical synchronous transmission system is standard STM-1

transmission equipment. Based on the existing sound technologies of Huawei

SBS155/622 products, it is fully compatible with the existing SBS155/622 products.

According to networking requirements, it can be configured as a TerminalMultiplexer (TM), Add/Drop Multiplexer (ADM) or regenerator (REG). It can be used

to form ring-, chain-, and point-to-point network topological structures. It can also be

combined with Huawei SBS155/622H and SBS155/622B products to form complex

networking structures so as to enhance network performance and provide powerful

services protection functions (channel protection or multiplexing segment protection

solutions are optional). It is a cost-effective optical transmission device built in BTS.

The ASU has inherited merits of powerful network management capacity and

convenient operations from Huawei's standard transmission equipment. It uses the

same set of network management system as all the Huawei SBS series of SDH


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optical transmission equipment. It can completely meet the OAM & P function

specified in ITU recommendations.

3) Interfaces

ASU provides the following interfaces:

Line optical interfaces: 2 (interface type: SC/PC interface)

Electrical interface: 4~8 (E1/T1)

Order wire: 1

Ethernet interface: 1

User RS232 port (point to point): 1

Network management interface: Ethernet/RS232

2.4.6 ABB

I. General

In practice, chain networking is usually adopted in BSS networking. This networking

mode has the advantage of simple structure and low cost, but also it has the

disadvantage that when power failure occurs at a site, all services of the

downstream sites will be interrupted. ABB provides of Abis interface bypass function

as a solution to the problem above.

II. Functions

ABB is applied in the environment of BTS chain networking. It is in charge of the

BTS transmission trunk. When power failure occurs at a certain level (in the middle)

of BTS in the chain networking, ABB will bypass the Abis transmission line off this

site, and directly connect it to the downstream BTS. In this way, even if power failure

occurs at the middle level site in chain networking environment, the services of the

downstream site will not be affected. See Figure 2-10 .

BSC ABB

TMU

ABB

TMU

ABB

TMU

Site1 Site2 Site3

Figure 2-10 ABB working principle

ABB can also perform loop back at the transmission line, so that in the case of

power failure at the last level BTS, ABB will loop back the E1 signal for BSC to

detect the quality of the entire transmission link.


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III. Location of Board

ABB shares the same slot with TEU, therefore the size of the board and the

interface definition is consistent with TEU. Since BTS30 has only one TEU slot, ABB

is to take the slot of TEU.

2.4.7 ABA

ABA realizes the communication between ABB and TMU. ABB communicates with

TMU via CBUS3. But the slot of ABB does not provide the connection with CBUS3.

Therefore, ABA is used to provide the connection between them. Via ABA, part of

the signals from ABB (e.g. the signals of ABA on position) can be transmitted to

CBUS3 on the backplane of common resource frame.

2.5 Other Parts of the Cabinet

2.5.1 TDU

The TDU is at the top of BTS cabinet, serving as the control center of BTS clock

transfer. It receives the clock source (SREF, OBCLK, FCLK, FN) from TMU, and

forwards the clock source to the TRXs in this cabinet and the parts in other cabinets.

TDU can also transfer other signals (e.g. alarm signals).

The main functions of the TDU are:

Provides bus-control interface

1) Clock Bus

In the simplex RS485 bus structure, it distributes the clocks generated by the active

TMU in the basic cabinet to various extension cabinets, The clock signal process is

shown in Figure 2-11 .

TMU TDUBoards in the maincabinet

Boards in theextension cabinet

A-bis

Figure 2-11BTS clock signal process


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2-22

The TDU of each cabinet is connected to the bus. After receiving clock signals, it

transfers them to the TRX in the local cabinet.

The TDU of the last cabinet is connected to an adapter. All the TDUs form a

chrysanthemum ring of a clock bus. as shown in Figure 2-12 .

CDU

TRX

CDU

CDU

TRX

TRX

TRX

TRX

TRX

PMU

TMU

TMU

Basic Cabinet

CDU

TRX

CDU

CDU

TRX

TRX

TRX

TRX

TRXPSU

PMU

Extension Cabinet

CDU

TRX

CDU

CDU

TRX

TRX

TRX

TRX

TRX

PMU

Extension Cabinet

PSU

PSU

Figure 2-12Clock bus connection in a synchronous cell

Connection path:

Upper cabinet TDUJP3

TDUJP1

TRBJC2

Cabletransfer Inner cabledistribution (Connect with 6 TRXs)Matching

Lower cabinet TDUJP4

TDUJP2

CMBJ24

Inner cabledistribution

Cabletransfer Cable

transfer

Inner cable

distribution

Figure 2-13Clock bus connection path

For the upper cabinet, JP3 should be configured with connector. For the lower

cabinet, JP4 should be configured with connector.

2) Data Bus (DBUS)

DBUS is for the data connection between TMU and TRX. Each TMU provides 2 full

duplex DBUS link and TRX connection, called DBUS1 and DBUS2.

The physical feature of DBUS is differential RS485, TDMA synchronous bus and

distribution of 32 timeslots is similar to that of PCM.

The active TMU has DBUS connections to each TRX in the same cabinet. The

active and standby links are led from the main cabinet to the 18 TRXs in the local

cabinet group. There is no DBUS connection between cabinet groups.


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For example, the signal connection between BTS30 cabinets is shown in Figure

2-14 .

Figure 2-14DBUS connection between BTS30 cabinets

The intra-cabinet signal connection is shown in Figure 2-15 .

Upper cabinetTDUJP6

TDUJP5

Cabletransfer


CMB J25(connect with TMU)


TRBJC3

TRBJC1

TDUJP7

TDUJP8


Cabletransfer

Lower cabinet

Inner cabledistribution(connect with 6 TRXs)

Figure 2-15DBUS connection path



3) Control Bus (CBUS)

CBUS1 is for the communication between the TMUs of this same site. It adopts

RS485 semi-duplex bus, asynchronous transmission. The link layer conforms to

HDLC protocol. The bus rate is 256 kbit/s.

Since only the PCM link in main cabinet group has the operation and maintenance

signaling of BTS. The master TMU in main cabinet group is to send the operation

and maintenance signaling to the slave TMUs in the two extension cabinet groups,

as shown in Figure 2-16 .


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Figure 2-16CBUS1 connection between BTS30 cabinets

The connection of the intra-cabinet signal is shown in Figure 2-17 .


Cabletransfer TDU

JP2

Inner cabledistribution CMB J24

(connect with TMU)

TDUJP4

TDUJP2

CMBJ24


Cabletransfer

Lower cabinet

Figure 2-17CBUS1 connection path

CBUS2 is for the control link between TMU and TRX.

The physical feature is differential RS485 interface, semi-duplex bus. The link layer

conforms to HDLC protocol. The bus rate is 2 M. The 2 M clock of DBUS is used as

the clock of CBUS2. There is no CBUS2 connection between cabinet groups.

The connection relationship between CBUS2 cabinet groups and the connection

path are similar to that of DBUS.

CBUS3 is for the connection between TMU and some low rate control parts, such as

CDU, PMU and environmental monitoring instruments.

The physical feature is differential RS485 interface. The link layer conforms to DLC

protocol, differential transmission and master/slave communication. The bus rate is

9.6 kbit/s. There is no CBUS3 connection between cabinet groups.


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Figure 2-18Connection of CBUS3 between BTS30 cabinets

The connection of the intra-cabinet signal is shown in Figure 2-19 .


TDUJP18

TDUJP5

Cabletransfer

Cabletransfer

Alarm box

CMB J25(connect with TMU and PMU)

TRBJC3


TRBJP1

TRBJP2

TRBJP3

Cabletransfer

CDU


CDU


CDU


TRBJC1

TDUJP7


Cabletransfer

Inner cabledistributionTDU

JP8

Cabletransfer

Lower cabinet

Figure 2-19CBUS3 connection path



4) Frequency Hopping Bus (FHBUS)

FHBUS is used in baseband FH. FHBUS physically shares the same cable with

CBUS2, CBUS3 and DBUS. The difference is that FHBUS connects only to TRX.

FHBUS is an 8 bit parallel bus, semi-duplex, and conforms to RS-485 criteria.

FHBUS is for the connection between all TRXs in the same cabinet group (forBTS30, at most 18). There is no FHBUS connection between cabinet groups.


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Main cabinet Extension cabinet

CDU

TRX

CDU

CDU

TRX

TRX

TRX

TRX

TRX

PSU

PMU

TMU

TMU

Extension cabinet

CDU

TRX

CDU

CDU

TRX

TRX

TRX

TRX

TRX

PSU

PMU

CDU

TRX

CDU

CDU

TRX

TRX

TRX

TRX

TRX

PSU

PMU

Figure 2-20FH bus connection between BTS30 cabinets

Connection path is shown in Figure 2-21 .


Cabletransfer TDU

JP5CMBJ25


TRBJC3

TRBJC1

TDUJP7

TDUJP8


Cabletransfer Lowercabinet


Inner cabledistribution(connect with 6 TRXs)

Figure 2-21FH bus connection path

For the top level of cabinet, JP6 should be configured with connector. For the last

level of cabinet, JP8 should be configured with connector.

Transfers E1 signals in the local cabinet

TMU provides 4 sets of identical circuits E1 for lines. Plus the 4 E1 lines on the

standby TMU board, there are altogether 8 E1 signals that are transmitted on the

coaxial cable to each cabinet top where the TDU sends them via coaxial cable to

BSC.

Provides alarm channels

Inputs of 8 external and 16 extended digital alarm signals and 8 analog alarm

signals, as well as outputs of 8 digital control signals, are sent via the TDU to the

TMU board and the environment alarm box (for detailed description, refer to section

2.7.1 of this chapter).

The input of the DC alarm signals of fuses and output of DC contactor control

signals are also sent via the TDU to the PMU of this cabinet.


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2.5.2 FMU

FMU is in the fan box, used to control the fans.

The small size of the base station cabinet sets higher requirements for heatdissipation. A perfect heat dissipation design should include air tunnels (mainly

related to structure), expected dissipation amount (mainly related to circuit working

temperature, environment temperature, system total power and efficiency), original

calculation of system heat (simulation makes better result if tools are available), fan

type, fan monitoring unit, and system heat design testing and verification, etc.

The functions and circuits of FMU are based on the fan type, specific fan control

requirements and control modes, as well as the specific system heat design.

It performs the following main functions:Fan feeding

This part of circuit consists of power supply filtering and power supply voltage

dropping. It completes the processing works from system power supply to the

working power supply needed by fans, and provides feed to the fans.

Fan speed control

It controls the fan speed so that the fan can maintain a constant rotation speed,

meeting the system heat design requirements.

Alarm detection

Fan faults have 2 types, blocking and short-circuiting, both may stop fan running.

The FMU monitors the fan rotation speed, and determines the fan status (normal or

faulty). If fault is detected, alarm will be reported to the PMU.

Interfaces

The FMU provides the following ports: fan 24V power supply input port, fan box

power supply input port, and fan fault alarm terminal, which outputs low levels in

case of fan failure.

2.5.3 Switch Box

The +26V DC from the output busbar of the power supply backplane is inputted to

the switch box, and after passing the air switches for different power consumption

units and over-current protectors, it is outputted to the terminals on the backplane.

These terminals are connected to the power input terminals of different power

consumption units, thus achieving distributed power supply.


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The distributed power supply ensures the normal power supply to other units when

the supply to one unit fails.

The power supply to CDU, EDU, TRX, TMU, PBU, etc., can be controlled through

the switches on the front panel of the switch box.

2.5.4 Fan Box

There are two kinds of fan boxes, one small fan box below the switch box, and two

large boxes below the second TRX/CDU frame. Both kinds of fan boxes are

equipped with FMU.

The fan box uses mixed-flow fans, which feature strong wind rate and pressure. The

FMU ensures the normal operation of fans, and reports alarms in case of failure.

2.5.5 Air Box

The air box is at the bottom of the cabinet, under the first TRX/CDU frame. It is the

channel for introducing the external cool air into the cabinet to ensure the normal

operation of the whole BTS system.

2.6 Antenna and Feeder System

The antenna and feeder system of the base station mainly consists of the antenna,feeder, jumper, lightning arrester, tower-top amplifier (optional), etc. as shown in

Figure 2-22 . Its main function is to transmit modulated signals and receive signals

from mobile stations.

C a b

i n e t

Tx/Rx antenna

T o w e r - t o p

a m p l

i f i e r

Diversity Rx antenna

L i g h t n i n g

a r r e s

t e r

Antenna and Feeder System

Feeder

Feeder

T o w e r - t o p

a m p l

i f i e r

L i g h

t n i n g

a r r e s t e r

Figure 2-22Composition of antenna system


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2.6.1 Antenna

The antenna is the terminal of transmitting and the start of receiving. Antenna type,

gain, coverage pattern (including azimuth angle, pitch angle and declination angle),and front/back ratio will affect system performance. A network planner sets these

parameters according to network requirements.

I. Antenna gain

Antenna gain indicates the antenna feature of electromagnetic radiation in specific

directions. Normally, the higher the gain, the stronger the field strength in the main

beam radiation direction (which means a larger coverage area), but nearby blind

area might occur.

II. Antenna pattern

The antenna pattern describes the radiating abilities of antennas in all directions.

(usually in terms of horizontal azimuth angle and declination angle).

Usually, there are two kinds of base station antennas: omni and directional antennas

according to the azimuth angle: Omni antenna radiates the waves in all directions i.e.

along 360 degrees, whereas directional antennas radiates along 120, 90, or 65

degree.

The declination angle of the antenna can be achieved through mechanicaladjustment or electric tuning. BTS directional antennas with declination angle of 0

or 2 are available. Through adjustment by pitch adjuster, a wider angle can be

achieved (e.g. 0 ~ 10 ).

III. Polarization

Polarization is used to describe the direction of electric field. Mobile communication

antennas include single polarization antennas and dual polarization antennas. For

the later antennas, two antenna's polarization directions are vertical to each other.

So using of dual polarization antennas can reduce the number of antennas needed.

IV. Diversity

Radio communication is much more complex than fixed line communication

because of electromagnetic waves propagation. In urban areas, the propagation of

electromagnetic wave has the following features:

The average value of field strength varies slowly with distance and time. Such

variation abides by the logarithmic normal distribution. This is called slow

fading.


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The instantaneous value of field strength presents a selective fading along

transmission paths due to multi-path transmission. Its fading pattern abides by

the Rayleigh distribution. This is called fast fading.

Either fast fading or slow fading will affect the quality of mobile communications, oreven lead to communication interruption. The diversity receiving technology is one

of the most effective ways to deal with fast fading. Two receiving signals from two

different antennas effectively decrease the fading effect.

Diversity includes polarization diversity and space diversity. In existing mobile

communication systems, either the space diversity or polarization diversity can be

used. Theoretical inferences show that in case of space diversity, when the distance

between two antennas is greater than 10 wavelengths, desirable diversity gain can

be obtained. Polarization diversity enjoys the advantage of convenient antenna

installation and space saving and is more widely used nowadays.

V. Antenna spacing

To reduce interference on the receivers, enough spacing should be reserved

between receiving and transmitting antennas. Spacing is determined by the

out-band noise of the transmitter and receiver sensitivity. In the GSM system, the

antenna spacing should be greater than 30dB.

2.6.2 Feeder

To reduce transmission loss, the base station uses low loss RF cables. There are

several types of main feeders available, including 7/8-inch and 5/4-inch. 1/2-inch

super-flexible jumpers are used between the antenna and the main feeder, between

the antenna and the tower-top amplifier, and between the cabinet and the lightning

arrester.

2.6.3 Lightning Arrester

The lightning arrester is used to prevent damage of lightning current to the antenna

and feeder system. Usually, there are two kinds of lightning arresters. The first type

applies the microwave principle to conduct the low frequency lightning current to the

ground so as to discharge the current. The second one is a discharging tube, when

the voltages at both ends of the discharging tube reach a certain value, the tube

conducts and discharges the large current. The second technique is used in the

BTS30.


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2.6.4 Tower-top Amplifier (Optional)

To further improve the signal quality, Huawei BTS30 offers a complete solution by

providing the tower-top amplifier.The tower top amplifier is optional. Normally it is installed close to the antennas,

consisting of triplex filter and low noise amplifier. The triplex filter is actually a device

composed of two duplex filters.

Signals from the antennas first pass through the triplex filter to filter out the out-band

interference, then the low noise amplifier amplifies the weak signals. Finally the

amplified signals are sent over the low loss cable to the BTS, as shown in Figure

2-23 .

The purpose of the tower top amplifier is to enhance the receiving sensitivity of thebase station. So the tower-top amplifier is required to have a low noise coefficient.

The power of the signals received on the antenna varies greatly with the distance

between the MS and the base station. This requires that the tower- top amplifier

have a greater dynamic range.

Besides, the tower-top amplifier also has the by-pass function in case of DC power

failure.

The DC power supply of tower-top amplifier is fed through the center conductor of

the receiving feeder by the CDU. Since it is an outdoor device, a reliable waterproofsealing is required.

The tower-top amplifier can operate under -40 C~60 C.

Bias-T

Low noiseamplifier

Transmitting filter

Receivingfilter

By-path

DC

BTS

Triplex tower-top amplifier

Receivingfilter

Figure 2-23Structure of the triplex tower-top amplifier


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2.7 Power Supply System

2.7.1 Overview

The BTS30 built-in power supply system provides +26V DC to the base station.

Together with power distribution, lightning arrester, and monitoring systems, they

form a complete power supply system.

To meet the power supply requirements of different users, two special AC/DC and

DC/DC power supply systems are provided, which are used respectively for the AC

power supply cabinet and the DC power supply cabinet.

The AC/DC power supply system has battery charging functions. The PSU power

supply unit described above consists of the AC/DC power supply module and theDC/DC power supply module.

According to the general design requirements of the BTS30, multiple cabinets can

be configured at a site, which are interconnected via multiple sets of buses to

achieve flexible, convenient and reliable network configurations. So a proper power

distribution monitoring solution is required for the power supply system, e.g.,

centralized anti-lightning protection, and AC and DC power distribution. That is, each

cabinet should have its own power supply system.

The power supply monitoring board installed on each cabinet monitors its own

power supply module and part of environment parameters inside the cabinet, and

reports them to TMU via general monitoring bus.

The AC and DC inputs of the system has the following 3 modes, among them only

one can be selected:

220VAC: used for the AC power supply cabinet, with the AC/DC module and

batteries attached.

-48VDC: used for the DC power supply cabinet with the DC/DC module, no battery

attached.

+24VDC: used for the DC power supply cabinet, without AC/DC module or DC/DC

module, nor any battery.

The power supply input goes through the AC EMI filter or DC EMI filter to the wiring

terminals on the top of the cabinet, then to the backplane busbars in the common

frame. 220V AC and -48V DC are input to different sockets from the backplane

busbar, so as to avoid mistaken insertion.

No matter whether it is the 220V AC power distribution, -48V DC power distribution

solution, or the +24V power distribution, their outputs are all collected to the output


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busbars of the power supply backplane. Then, the 26V DC is led out from the

busbar, along the cabinet wiring trough to the copper bar of the distribution box.

The 26V DC input from the battery is connected to the current diverter on the power

supply backplane, and then distributed through the distribution copper bar in thedistribution box to various power-consuming modules. They are respectively led out

from the distribution copper bar, passing the over-current protection devices set

separately for each power-consuming unit in the distribution box, and then

connected to the outlet terminals on the backplane of the distribution box. When the

power to a unit is cut due to over-current, other units will not be affected.

The illustration of the entire power supply system is as shown in Figure 2-24 .

Anti-lightning

power

distribution

Battery group Fuse

AC/DC(DC/DC)module

AC/DC(DC/DC)

AC/DC(DC/DC)

EMIfilter

EMIfilter

EMI filter

220V AC IN

-48V DC IN

+24 VDC IN

PMU

26V DC OUT

DC contactor

Load

module module

AC/DC(DC/DC)module

Figure 2-24The BTS30 power supply system

2.7.2 Overall Structure

I. AC/DC power supply system

220V AC is led in after passing through the AC input anti-lightning power distribution

unit and the AC EMI filter on top of the cabinet. It then passes downward along the

cabinet wiring trough to the input busbar on the backplane of the power supply

frame.


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On this backplane, there are the 220V AC power supply busbar, -48V DC busbar,

and 26V DC busbar. When the AC/DC power supply module is used, the -48V DC

busbar should not be connected to.

A fully configured cabinet uses the 4 AC/DC (26V/25A) modules (3 active + 1standby), which can ensure a maximum output of 2600W.

The module size is 285mm233mm (6U)60.5mm(12E).

The structure of the AC/DC power supply system is shown in Figure 2-25 (For the

battery part, refer to Figure 2-24 ).

AC input anti-lightning power distribution unit A1441Z

PSU PSU PSU PSU

220V AC INPUTInput busbar

Output busbar

26V DC OUTPUT

DC distribution copper bar

PMU

Figure 2-25Structure of the AC/DC power supply system

II. DC/DC power supply system

The DC/DC power supply system uses a backplane the same as that for the AC/DC

system. -48V DC first passes through the DC EMI filter on top of the cabinet, then

downward along the cabinet wiring trough to the input busbar of the power supply

backplane.

On the backplane of the power supply frame, there are 220V AC, -48V DC and 26V

DC power supply busbars. When the DC/DC power supply module is used, the

220V AC busbar should not be connected to.

In full configuration, 4 DC/DC 26V/25A modules (3 + 1 standby) are used to provide amaximum output of 2680W.

The module size is the same as that of the AC/DC module, i.e., 285mm233mm (6U)

60.5mm (12E).

The structure of the DC/DC power supply system is shown in Figure 2-26 .


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PSU PSU PSU PSU

Input busbar

Output busbar

26V DC OUTPUT

DC distribution copper bar

-48 V DC INPUT

PMU

Figure 2-26Structure of the DC/DC power supply system

2.8 Environment Monitoring System

It is not practical to monitor the BTS locally. Compared with the switch room, the

facilities in the BTS room are quite simple, and their operation environment can be

rather hostile. To ensure the normal operation of the base station equipment, and to

cope with various possible emergencies (e.g. fire, floods), a perfect environment

monitoring system is required.

The environment monitoring system consists of BTS alarm port and environment

monitoring instrument. BTS30 supports 14 switching/digital inputs, 8 digital outputs

and 8 analog inputs, collects external alarms and controls external equipment.

EAC1 and EAC2 on the cabinet top are the physical ports for external extended

alarm and EAC alarm report.

The environment monitoring instrument is used to get the information on external

environment. It reports the alarm to BSC via TMU if the external environment

parameters meet the corresponding alarm terms. The external extended alarm is

switching (digital) signals, which is different from the EAC alarm.

The following gives the alarm functions provided by the environment monitoring

instrument.

2.8.1 Outlook of Environment Monitoring Instrument

The environment monitoring instrument consists of such sensors as host, humiture

probe, smoke probe, infrared probe, infrared tube, door status (position) switch etc.

Each probe connects to the host with cables.


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Dimensions of the host:

Length (L) x Width (W) x High (H) = 390mmx270mmx55mm. The outlook of the

environment monitoring instrument is shown in Figure 2-27 .

Figure 2-27Outlook of Environment Monitoring instrument

2.8.2 Function Provided by Environment Monitoring Instrument

The environment monitoring instrument automatically monitors and generates

temperature, humidity, smog, and intruder alarms according to the set values.

Besides, it can start corresponding protection devices for fire-fighting moistening

and anti-burglary protection, etc. Moreover, it can receive commands from the

control center to modify parameters and start/stop protection devices.

The features of the environment monitoring instrument include:

Realtime display of temperature and humidity

Time display

Generating alarms including fire, smog, temperature, humidity, water and 3

kinds of burglar alarms

A panel control keyboard

10 switch parameter inputs (opto-electrical isolation)

6 relays (maximum 5A/220V) to drive external executors

2 PWM (pulse width modulation) outputs (8-bit resolution, with a basic clock

500kHz)Driving of 7 independent open-collector gates (absorbing current: 300mA)

Capable of communicating with TMU via the RS422 port

2.8.3 Environment Monitoring Instrument Inputs

Temperature: frequency-type temperature and humidity transducer

Humidity: frequency-type temperature and humidity transducer

Smog: Ion type smoke sensitive probe or opto-electrical type smoke sensitive

probe


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Flame (optional): fire probe or high temperature difference sensitive probe

Anti-burglary detection: infrared detector, opto-electrical detector, and magnetic

sensor

Other sensor inputs: besides the quantitative temperature and humidity signalparameters, the above sensor input signals can be extended into 10 switch

parameters

2.8.4 Alarm Indicators

Ten red indicators on the panel are provided, which correspond sequentially to the

following alarm parameters:

Fire alarm: fire alarm is determined by the high temperature and smog probe

Smog alarm: smog sensor timeout alarm

Temperature upper limit: an alarm is generated when the environmenttemperature exceeds the set temperature limit

Temperature lower limit: an alarm is generated when the environment

temperature is lower than the set temperature limit

Abnormal humidity: an alarm is generated when the environment humidity goes

beyond the normal range between the upper and lower limits

Water: the alarm is generated when water is detected

Air-conditioning: an alarm is generated in case of failure of air-conditioning

equipment.

Opto-electrical: used for anti-burglary purpose, the alarm is generated when theopto-electrical switch is triggered.

Infrared: used for anti-burglary purpose, the alarm is generated when the

infrared sensor detects outputs.

Access control: used for anti-burglary purpose, the alarm is generated when

the magnetic access control switch is triggered.

If there are multiple input signal channels for the same kind of sensor, alarm in any

channel will be regarded as the same kind of alarm, regardless of the specific

channel sending the alarm. Except temperature and humidity sensors, all other

sensors can be extended up to 10 channels at the most.

2.8.5 Executing Devices

The BTS30 environment monitoring function involves the following executing

devices:

Six constant on/off relays (A~F) which function as the control and protection

devices, operating under 1A/220V. Their specific application can be determined by

the user. Their default settings are as follows:


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the same as that of the first level. The protection circuit of the third level clamps the

residual voltage at about 100V.

Its functional blocks are shown in Figure 2-28 .

Over-currentprotection

Inductor Inductor -48V -48V

GND GND

Input Output




V-sensitiveresistor

V-sensitiveresistor

V-sensitiveresistor

TVScomponent

Figure 2-28Functional blocks

2.9.2 Lightning Protection for AC Power Supply

I. Lightning current lead-in paths

AC power supply suffers directly from lightning strike or induced lightning.

II. Principle of the AC lightning arrester

The principle of the AC lightning arrester is similar to that of the DC lightning arrester.

The functional blocks are shown in Figure 2-29 .

Slow-blow fuse

V-sensitive resistor

Discharge tube

Inductor

Air switchIN OUT

V-sensitivecomponent

Figure 2-29Functional blocks of the AC lightning arrester

The lightning protection system features:


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Symmetric design, N and L wires can be connected freely without affecting the

performance.

2-level lightning protection guarantees high reliability and less possibility of

damage by lightning strikes.2-level protection and 2-level alarm are provided (visible alarm. If either level

fails, corresponding indicator will be off. On/off signals of the dry contactor are

also provided). The circuits are designed in parallel so that the maintenance

personnel can repair them without power-off.

The total through-flow current is 40A. There are two output terminals so that

two cabinets can share one anti-lightning box.

2.9.3 Lightning Protection for Trunk Cables

There are three kinds of trunk cables in BTS30: 75 coaxial cable (E1), 120 twisted-pair cable (E1) and optical fiber (SDH). In case of optical fiber connections,

fiber pigtail is used so that its lightning protection is not considered.

BTS30 E1 interface protection is realized by adding a E1 lightning protection board

to the top of the cabinet. Each board has eight pairs of E1 protection units and two

DB37 connectors. The E1 lightning protection board is illustrated in Figure 2-30 .

TX0

TX1

TX2

TX3

TX4

TX5

TX6

TX7

RX0

RX1

RX2

RX3

RX4

RX5

RX6

RX7

T o

L i n e

T o

E q u

i p m e n

t

LightningProof Box

Figure 2-30E1 lightning protection board

All E1 cables are protected by the lightning protection board, which is able to avoid

the thunder current from entering the cabinet via E1 cable. Even the strong current

impact can be discharged by the discharging tube. The lightning protection board is

illustrated in Figure 2-31 .


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E1-Tip E1-Tip

E1-Ring E1-Ring

PE PE

Discharging tube

Discharging tube

4.7

4.7

Figure 2-31Circuit of lightning protection board

Documents

02 Hardware Architecture