Flexi EDGE BTS Feature Description

Nokia Flexi EDGE BTS FeatureDescriptions

DN70124104Issue 3-0 en

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471840ANokia Flexi EDGE Base Station, Rel. EP1.1,Product Documentation, v.1

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2 (81) # Nokia Siemens Networks DN70124104Issue 3-0 en

Nokia Flexi EDGE BTS Feature Descriptions

Contents

Contents 3

1 Summary of changes 5

2 Overview of features in Nokia Flexi EDGE BTS SW release EP1.1 7

3 Data/Voice 93.1 BSS20088 Dual Transfer Mode 93.2 BSS9006 General Packet Radio Service (GPRS) 103.3 BSS10083 Enhanced General Packet Radio Service (MCS-1 - MSC-

9) 113.4 BSS10074 Support of PBCCH/PCCCH 143.5 BSS7003 High Speed Circuit Switched Data and BSS7037 14.4 kbit/s

Data Services 143.6 BSS10004 Adaptive Multi Rate Codec (AMR) 163.7 BSS7005 Intelligent Frequency Hopping and BSS6114 Intelligent

Underlay-Overlay 17

4 Interworking 194.1 BSS10101 GSM-WCDMA Interworking 194.2 BSS11086 Support for Enhanced Measurement Report 19

5 Operability 215.1 BSS11047 Intelligent shutdown for Flexi EDGE BTS 215.2 Remote mode of Nokia Flexi EDGE BTS Manager 225.3 BSS10063 Rx Antenna Supervision by Comparing RSSI 245.4 Collection and display of raw RSSI measurements 255.5 Settable RSSI sample limit 255.6 BSS9068 BTS SW management 255.7 BSS9067 Runtime diagnostics and BTS alarms 265.8 BSS9058 BTS fault recovery 265.9 BSS9063 Abis loop test 275.10 BSS9062 BTS supervision 275.11 BSS9061 Temperature control system 285.12 BSS9060 TRX Test 285.13 TRX Loop Test 305.14 BSS9059 Nokia BTS resets 305.15 Auto-detection of Site Configuration and RF Cable Auto-detection 315.15.1 BSS9056 Auto-detection of Site Configuration 315.15.2 RF Cable Auto-detection 315.16 Optical Converter Module (EOCA) autodetection and runtime polling 355.17 BCCH antenna VSWR measurement 355.18 48 V DC input voltage supervision 365.19 Antenna Hopping 37

6 Site solutions 396.1 BSS10046 Multi BCF Control 396.2 BSS9055 Clock Synchronisation between Base Stations 40



Contents

6.3 BSS10069 Synchronised BSS 416.3.1 BSS20371 BSS Site Synchronisation Recovery Improvement 426.3.2 BSS11073 Recovery for BSS and Site Synchronisation 426.4 Operating bands 446.5 BTS2043 BTS External Alarms and Controls (EAC) 456.6 BTS2020 RX antenna diversity 466.7 BTS configurations 466.7.1 Upgrade-optimised configurations 476.7.2 Cost-optimised configurations 476.8 Nokia Flexi EDGE BTS Feederless and Distributed Site concept 476.8.1 Feederless site 486.8.2 Distributed site 516.9 Distributed BTS with Optical Converter modules (EOCA) 52

7 Basic GSM operation 577.1 Basic GSM features 577.2 BSS6071 Enhanced Full Rate Codec 587.3 BTS2023 Downlink and uplink DTX 587.4 BTS2503 Compressed Abis timeslot allocation 587.5 BTS2067 Fast Associated Control Channel (FACCH) Call Setup 597.6 BSS7036 Dynamic SDCCH Allocation 597.7 BTS2024 Synthesised frequency hopping 607.8 BTS2013 Baseband Frequency Hopping 607.9 BTS2037 Air interface measurement pre-processing 617.10 BTS2012 BTS time base reference from PCM 617.11 BTS2133 Short Message Service (SMS) point-to-point 617.12 BTS2033 Short message cell broadcast 617.13 BSS6025 Short Message Service Cell Broadcast with Discontinuous

Receiving (SMS-CB DRX) 617.14 BSS6083 Mobile Station (MS) speed detection 637.15 BSS11052 Dynamic Frequency and Channel Allocation (DFCA) 64

8 Transmission 698.1 Basic transmission 698.1.1 Abis Trunk Transmission for E1 (ETSI) interface 698.1.2 Abis Trunk Transmission Allocation for T1 (ANSI) Interface 708.1.3 Abis Trunk Signalling 708.1.4 Network Synchronisation 718.1.5 Transmission equipment management 718.1.6 Support for Nokia Microwave Radio Links 728.1.7 BSS9065 Transmission Operability 738.2 Transmission solutions 748.2.1 PDH traffic routing 748.2.2 BSS 30280 Abis loop protection 748.2.3 Redundant Abis Trunk 778.3 BSS10045 Dynamic Abis allocation 778.4 BSS5850 Satellite Abis 78

Appendix A Other features 81A.1 Other features 81



1 Summary of changesChanges between issues 3-0 and 2-0

New features or feature enhancements in the EP1.1:

. Remote mode of Nokia Flexi EDGE BTS Manager :

information on the alarm 7801 MMI CONNECTED TO BASESTATION has been added.

. Raw RSSI measurement data:

new section added to chapter Operability.

. Settable RSSI sample limit:


. EOCA autodetection and runtime polling:


. BSS9062 BTS supervision:

monitoring of local and remote EOCAs has been added.

. Auto-detection of Site Configuration and RF Cable Auto-detection:

information on the auto-detection of an EOCA pair has been added.

. Antenna Hopping:


BCCH antenna VSWR measurement

information on plugged out Tx cable added.

. Nokia Flexi EDGE BTS Feederless and Distributed Site concept:

new section added to chapter Site solutions.

. Distributed BTS with Optical Converter modules (EOCA):



Summary of changes


. BTS configurations:

information on the support for 24 TRXs has been added.

. BSS6083 Mobile Station (MS) Speed Detection:

new section added to chapter Basic GSM operation.

. BSS11052 Dynamic Frequency and Channel Allocation (DFCA):

new section added to chapter Basic GSM operation.

. BSS5850 Satellite Abis:

new section added to chapter Transmission solutions.

Changes between issues 2-0 and 1-0

New features or feature enhancements in the EP1 CD1.0 delivery:

. BCCH antenna VSWR measurement:


. 48 V DC input voltage supervision:


. Cost-optimised configurations:


In addition, the following sections have been added/updated:

. RF Cable Auto-detection: new section added to chapter Operability.

. BSS9068 BSS SW management, in chapter Operability: updated.

. BSS9059 Nokia BTS resets, in chapter Operability: updated.

. Q1 Interface between the BTS and Transmission Equipment, inchapter Transmission: updated, renamed as TransmissionEquipment Management and moved to section Basic transmission.



2 Overview of features in Nokia FlexiEDGE BTS SW release EP1.1

Operating and Application SW

Nokia BSS12 Software consists of Operating Software and ApplicationSoftware:

. Operating Software refers to basic functionalities of a product.

. Application Software refers to optional features.

The BSS12 system features are available in the following network elementreleases: S12, EP1.1.

For more information on the features, see Nokia GSM/EDGE BSS SystemDocumentation and Nokia BSC/TCSM Product Documentation sets.

For general guidelines related to licensing, see BSS Licensing in the BSSSystem Documentation.



Overview of features in Nokia Flexi EDGE BTS SW release EP1.1



3 Data/Voice

3.1 BSS20088 Dual Transfer Mode

Dual Transfer Mode (DTM) provides mobile users with simultaneouscircuit-switched (CS) voice and packet-switched (PS) data services. Thismeans that users can, for example, send and receive e-mail during anongoing phone call.

In dual transfer mode, the mobile station (MS) is simultaneously indedicated mode and in packet transfer mode, so that the timeslotsallocated for each MS are consecutive and within the same frequency.

Benefits

With DTM, the operator can expand the service portfolio to offer usersenhanced services in a GSM/EDGE network. DTM allows the operator toprovide a wide range of services that demand a simultaneous CS and PSconnection. Mobile users can use data services, such as file transfer, webbrowsing, video sharing, and mobile netmeeting, during a speech call. Thismakes it possible to launch services similar to UMTS class A services alsoin 2G networks. In addition, these services can be used to complement the3G coverage in places where there is no 3G network coverage.

BTS functionality support

The BTS supports DTM through the normal BTS support of CS and PSservices.

Interaction with other features

DTM supports all full rate speech codecs. The CS speech codec selectionfor DTM is similar to the selection mechanism used for a plain CSconnection. In addition, the DTM PS channels can be multiplexed in asimilar way to normal GPRS/EDGE.



Data/Voice

3.2 BSS9006 General Packet Radio Service (GPRS)

General Packet Radio Service GPRS provides packet radio access forGSM mobile stations.

By sharing the channels provided by various network elements andtransmission systems, the cellular network resources are used moreefficiently for data services than with circuit switched data services.

All mobile stations share the radio resources in a cell, and use the radioresources only when sending or receiving data.

The Channel Coding Unit (CCU) in the BTS performs the channel codingfor the following ETSI defined coding schemes:

. Channel Coding Scheme 1 (CS1) 9.05 kbit/s




In packet transfer mode, the mobile station must use the continuous timingadvance procedure. This procedure is carried out on all packet datachannels (PDCHs).

Coding Schemes CS3 and CS4 (BSS11088) is an application softwareproduct, and it requires a valid licence in the BSC. CS3 and CS4 provide aconsiderable gain in data rates for GPRS mobile stations not supportingEGPRS (the mandatory RLC header octets are excluded from the datarate values).

Link Adaptation (LA)

Nokia Flexi EDGE BTS supports PCU with GPRS link adaption byproviding the measurements for the uplink radio blocks.


CS3 and CS4 do not fit to one 16kbit/s Abis/PCU channel and require theuse of Dynamic Abis Allocation.



3.3 BSS10083 Enhanced General Packet Radio Service(MCS-1 - MSC-9)

Enhanced General Packet Radio Service (EGPRS) supports high ratepacket data services across varying channel conditions. EGPRS is built ontop of the packet switched data service, GPRS. As the table below shows,EGPRS supports higher data rates compared to the basic GPRS, usingseveral Modulation and Coding Schemes (MCSs). The speed in radioresources is fixed for GMSK and 8PSK, but because the amount ofchannel coding varies, the user data rate varies depending on the MCS.

Table 1. Peak data rates for single slot EGPRS

MCS Modulation Code Rate Family User Rate

MCS-1 GMSK .53 C 8.8 kbps

MCS-2 GMSK .66 B 11.2 kbps

MCS-3 GMSK .80 A 14.8 kbps

MCS-4 GMSK 1 C 17.6 kbps

MCS-5 8PSK .37 B 22.4 kbps

MCS-6 8PSK .49 A 29.6 kbps

MCS-7 8PSK .75 B 44.8 kbps

MCS-8 8PSK .92 A 54.4 kbps

MCS-9 8PSK 1 A 59.2 kbps

Gaussian Minimum Shift Keying (GMSK) modulation provides the robustmode for wide-area coverage, while 8 Phase Shift Keying (8PSK) provideshigher data rates.

The MCSs are organised into families to allow a re-segmentation of thedata block for link adaptation. Since higher protection means lowerthroughput, the protection that best fits the channel condition is chosen formaximum throughput.

Incremental Redundancy (IR)

Incremental Redundancy (IR) is an efficient combination of twotechniques: Automatic Repeat reQuest (ARQ) and Forward ErrorCorrection (FEC). In the ARQ method, when the receiver detects thepresence of errors in a received data block, it requests a re-transmission ofthe same data block from the transmitter. The process continues until an



Data/Voice

uncorrupted copy reaches the destination. The FEC method addsredundant information to the user information at the transmitter, and thereceiver uses the information to correct errors caused by disturbances inthe radio channel.

In the IR scheme (also known as Type II Hybrid ARQ scheme), only asmall amount of redundancy is sent first, which yields a high userthroughput if the decoding is successful. However, if the decoding fails, are-transmission takes place according to the ARQ method. Using IR, there-transmission of the data block is different from the initial transmission.The transmitter sends additional redundancy that is decoded at thedestination with the previously received information to allow for errorcorrection. Since the combination includes more information than anyindividual transmission, the probability of correct reception is increased.

The IR mechanism in EGPRS is designed around nine Modulation andCoding Schemes (MCSs). The basic characteristics of each MCS are itsfixed data rate and fixed protection level. For each of the MCSs, it ispossible to reach the same data rate with the same protection level, butwith a different protection scheme.



Figure 1. Incremental Redundancy scheme

There are three protection schemes (P1, P2 and P3) for an MCS, asshown in the figure above. The data block is first protected with the P1 of acertain MCS, and sent over the air to the receiver, which tries to recoverthe data. If this phase fails, the received P1 is stored in the receiver'smemory for future use, and the transmitter sends the data block protectedwith the P2 of the same MCS. The receiver combines the received P2 withthe stored P1 and tries to recover the data from the combination of P1 andP2.This process continues until the data is recovered.

If after P3, the data still cannot be recovered, P1 is sent again andcombined with the stored P1, P2 and P3 (which reaches a protection levelof about four times P1), and so on until the data is recovered.

Data Block

One MCSP2 P3P1

P2

P2

P2

P1

P1

P1

P1

Stored

Stored

Receiver

Transmitter

No data

recovered

No data

recoveredCombination: Protection Level x 2

Protection Level 1

Combination: Protection Level x 3

Stored

P3

P3

1st transmission 1st re-transmissionupon reception failure

2nd re-transmissionupon reception failure



Data/Voice

Link Adaptation (LA)

Nokia Flexi EDGE BTS supports PCU with EGPRS link adaption byproviding the measurements for the uplink radio blocks.


EGPRS Modulation and Coding Schemes MCS-1 - MCS-9 require the useof Dynamic Abis Allocation.

3.4 BSS10074 Support of PBCCH/PCCCH

Support of Packet Broadcast Control Channel/Packet Common ControlChannel (PBCCH/PCCCH) allows dedicated common control channel(CCCH) capacity for (E)GPRS services.

The BTS transparently supports these channels as packet data channels.

3.5 BSS7003 High Speed Circuit Switched Data andBSS7037 14.4 kbit/s Data Services

High Speed Circuit Switched Data uses multiple parallel channels toprovide higher data rates for end-user applications, such as the WorldWide Web, file transfer and facsimile.

The BSS implementation is to reserve a multiple set of basic resources forone high-speed data call. The data rate and the number of reservedtimeslots vary between one and the defined maximum of the userapplication. The variable rate is needed for various common procedures,for example for handovers to a new cell if the requested data rate cannotbe given immediately. The BSS implementation of HSCSD supports thesimultaneous usage of a maximum of four radio timeslots (RTSLs) perHSCSD call.

The table below presents the corresponding maximum data rates withdifferent channel coding.

Table 2. Corresponding maximum data rates with different channel coding

Number of RTSLs 9.6 kbit/s 14.4 kbit/s

1 9.6 kbit/s 14.4 kbit/s



Table 2. Corresponding maximum data rates with different channel coding(cont.)

Number of RTSLs 9.6 kbit/s 14.4 kbit/s




Both asynchronous and synchronous bearer services and transparent andnon-transparent data services are supported. Transparent HSCSD usesfixed data rate throughout the duration of the call, but with non-transparentHSCSD, the data rate can be changed automatically during the call,because of increased traffic for example. The radio interface is eithersymmetric or asymmetric according to the mobile station (MS) capability.

During basic channel allocation, the system tries to keep consecutivetimeslots free for multichannel HSCSD connection. If there are not enoughappropriate free channels to fulfil the requested data rate, a non-transparent HSCSD connection is started with fewer channels thanrequested. At least one channel is allocated for a non-transparent HSCSDcall request if there are available resources in the cell. By use of theresource upgrade procedure, the data rate of the HSCSD connection canbe increased when an appropriate channel is available.

In a congested cell, the HSCSD load can be adjusted by BSCparameterisation. The resource downgrade procedure is used to lower theHSCSD connection data rate to release radio channels for otherconnections. If a transparent connection cannot be established in a cell, adirected retry can be attempted.

BSS7037 14.4 kbit/s GSM Data Services

With the 14.4 kbit/s GSM Data Services, the speed of one timeslotincreases from 9.6 kbit/s to 14.4kbit/s.

The 14.4 kbit/s channel coding has less error correction than 9.6 kbit/scoding. Therefore, there are some areas on the cell edges where using 9.6kbit/s coding will give a higher data throughput. The figure below showsthe results of Nokia simulations. Note that for transparent mode themaximum user throughput is 14.4 kbit/s, but in non-transparent mode, themaximum user throughput is 13.2 kbit/s. The maximum throughput isbased on the amount of available space in the coding block. Non-transparent data requires space for error checking, but transparent datadoes not.



Data/Voice

Figure 2. Typical data throughputs for 14.4 kbit/s (non-transparent) and 9.6kbit/s coding (this depends on the NW radio conditions)

The Automatic Link Adaptation (ALA) optimises the data throughput byautomatically choosing the channel coding most suitable to the radioconditions and by control of the power levels.

The 14.4 kbit/s Data Services can be combined with High Speed CircuitSwitched Data (BSS7003).

Note that Nokia Flexi EDGE BTS does not support transparent datahandovers because of limitations in fax protocols.

3.6 BSS10004 Adaptive Multi Rate Codec (AMR)

Adaptive Multi Rate Codec provides significantly better speech quality by:

. using better source coding algorithms that give better subjectivespeech quality for the same link capacity

. adaptively adjusting ratio of bits used for speech coding and channelcoding to always provide best subjective speech quality according tocurrent radio conditions.

With AMR it is possible to increase speech capacity by using HR modeand still maintain the quality of current FR calls. It consists of an adaptivealgorithm for codec changes and 8 different speech codecs (14 codecmodes) listed in the table below.

0

2

4

6

8

10

12

14

60 65 70 75 80 85 90 95 100

Percentage of Cell Area (%)

DataThroughputRate(kbit/s)

14.4

9.6



Table 3. Channel and speech codec modes for AMR

Channelmode

Channelcodecmode

Source coding bit-rate,speech

Net bit-rate,in-bandchannel

Channelcoding bit-rate, speech

Channelcoding bit-rate, in-band

TCH/FR CH0-FS

CH1-FS

CH2-FS

CH3-FS

CH4-FS

CH5-FS

CH6-FS

CH7-FS

12.20 kbit/s (GSMEFR)

10.20 kbit/s

7.95 kbit/s

7.40 kbit/s (IS-641)

6.70 kbit/s

5.90 kbit/s

5.15 kbit/s

4.75 kbit/s

0.10 kbit/s

0.10 kbit/s

0.10 kbit/s

0.10 kbit/s

0.10 kbit/s

0.10 kbit/s

0.10 kbit/s

0.10 kbit/s

10.20 kbit/s

12.20 kbit/s

14.45 kbit/s

15.00 kbit/s

15.70 kbit/s

16.50 kbit/s

17.25 kbit/s

17.65 kbit/s

0.30 kbit/s

0.30 kbit/s

0.30 kbit/s

0.30 kbit/s

0.30 kbit/s

0.30 kbit/s

0.30 kbit/s

0.30 kbit/s

TCH/HR CH8-HS

CH9-HS

CH10-HS

CH11-HS

CH12-HS

CH13-HS

7.95 kbit/s (*)

7.40 kbit/s (IS-641)

6.70 kbit/s

5.90 kbit/s

5.15 kbit/s

4.75 kbit/s

0.10 kbit/s

0.10 kbit/s

0.10 kbit/s

0.10 kbit/s

0.10 kbit/s

0.10 kbit/s

3.25 kbit/s

3.80 kbit/s

4.50 kbit/s

5.30 kbit/s

6.05 kbit/s

6.45 kbit/s

0.10 kbit/s

0.10 kbit/s

0.10 kbit/s

0.10 kbit/s

0.10 kbit/s

0.10 kbit/s

(*) Not supported, requires 16 kbit/s TRAU.

Codec mode adaptation for AMR is based on received channel qualityestimation in both the mobile station (MS) and the BTS.

The BTS and MS inform and request of codec used/to be used by in-bandsignalling.

3.7 BSS7005 Intelligent Frequency Hopping andBSS6114 Intelligent Underlay-Overlay

With Intelligent Frequency Hopping and Intelligent Underlay-Overlay, it ispossible to reuse frequencies more intensively, and therefore achieve ahigher radio network capacity. With Intelligent Frequency Hopping, it isalso possible to avoid frequency dependent fading on the radio path.

When Intelligent Frequency Hopping is in use, the operator can useIntelligent Underlay-Overlay simultaneously with frequency hopping in thesame cell. Either baseband (BB) or radio frequency (RF) hopping can beused.



Data/Voice

The different interference characteristics of the regular and super-reuselayers in Intelligent Underlay-Overlay require that the network plan forfrequency hopping is constructed separately for each layer. IntelligentFrequency Hopping enables the use of separate Mobile AllocationFrequency Lists of radio frequency hopping for the layers of an IntelligentUnderlay-Overlay cell. Baseband hopping is implemented by treating theregular layer as a normal cell and the super-reuse layer as a new hoppinggroup.

The operator can set the regular and super-reuse layers in IntelligentUnderlay-Overlay individually to hopping.



4 Interworking

4.1 BSS10101 GSM-WCDMA Interworking

In order for an operator to provide seamless coverage in areas whereWCDMA is not available, such as rural areas, inter-system handovers areintroduced. This feature facilitates handovers between GSM BSS andWCDMA RAN. When the WCDMA and GSM networks overlap, also aninter-system handover from GSM to WCDMA can be made to releasetraffic load in the GSM system.

Nokia Flexi EDGE BTS supports this feature as a GSM EDGE BaseStation.

4.2 BSS11086 Support for Enhanced MeasurementReport

Support for Enhanced Measurement Report (EMR) provides the systemwith enhanced serving and neighbour cell measurements. This is achievedby requesting the mobile station (MS) to use the EMR for reportingdownlink measurements.

Enhanced Measurement Report also provides the system with informationsuch as Downlink Frame Erasure Rate (DL FER), the usage of bit errorprobability (BEP) instead of RX Quality during the DTX frames, and thesupport for reporting WCDMA RAN neighbour cells. In addition, the EMRalso provides an extended range for the serving and neighbour cellsdownlink signal strength and the possibility to report altogether up to 15GSM and/or WCDMA RAN neighbour cells in one report.

These reports can be used by the network to enhance the genericperformance of the existing system, enable GSM/WCDMA interworking,and enhance several Nokia features, such as:



Interworking

. Automated Planning

. Dynamic Frequency Channel Allocation (DFCA)

. FER Measurement

. Intelligent Underlay Overlay (IUO) and Intelligent FrequencyHopping (IFH)

Interaction with other features:

. The network does not order an MS to use the EMR for reportingwhen an Idle Broadcast Control Channel (BCCH) Allocation List or aMeasurement BCCH Allocation List is used in active state in theserving cell.

. With Common BCCH Control, when a call is in a non-BCCHfrequency band, the serving cell BCCH frequency is added to theBCCH frequency list.

. When the EMR is used for reporting, also the serving cell BSIC isadded to the BSIC list before sending it to an MS.

Benefits

. Improved generic performance of the system

. Enables GSM/EDGE/WCDMA interworking

. Improved performance of statistics



5 Operability

5.1 BSS11047 Intelligent shutdown for Flexi EDGE BTS

To provide protection against a mains power break, the operator can equipa BTS with a battery backup system. The purpose of Intelligent Shutdownis to maintain the BTS site operation for as long as possible by reducingcapacity (units turned off or reduced to low power consuming modes) sothat only the essential site functions are maintained.

The BSC controls the reduction of the site capacity, which commandsindividual transceiver units to be shut down or started up.

On a BTS site basis, the user can define the service level of the site to bemaintained while the battery backup is in use. Also, two timers can bedefined, allowing the execution of the shutdown procedure in phases,reducing capacity in a controlled way. Three service level options areavailable:

. Full service – Service is maintained at full capacity for as long as thebattery power supply lasts. The two timers are ignored.

. Broadcast control channel (BCCH) backup – The BTS maintains fullcapacity until the first timer expires. After that, all active calls on non-BCCH transceivers are handed off. The non-BCCH transceivers areblocked from carrying any new calls and the BSC commands theBTS to shut them down. The BCCH TRX(s) are maintained to offerminimum service.

. Transmission backup – The second timer starts after the first onehas expired. After the expiry of the second timer, all active calls onBCCH transceivers are handed over. The BCCH transceivers areblocked from carrying new calls and the BSC commands the BTS toshut them down. Only the BTS transmission equipment power ismaintained to secure the functionality of a transmission chain for aslong as the batteries last.



Operability

When the mains power is restored, the BSC commands the BTS site topower all the shut down equipment and return back to full service.

Battery backup configurations for Flexi EDGE BTS:

. Flexi with Multi Integrated Battery Backup Unit (MIBBU)

. Flexi with Integrated Battery Backup Units

. 3rd Party Battery Backup Solution

The battery backup system for the Nokia Flexi EDGE BTS is selected inthe commissioning phase. When using a 3rd party battery backup solution,an external alarm line is designated to indicate a mains power loss/restoration from that equipment. This is specified in the configuration datathat the BSC sends to the BTS during the initial start-up or reset of theBTS. Battery Backup Units or Power Systems with Epsilon BTS can bemanaged via the BTS EAC interface (MIBBU/FPxA and non NOKIA BBU)or via FPA interface in ESMA (FPxA and MIBBU). If the EAC interface isused for BBU management, the EAC lines for BBU alarms have to beconfigured accordingly from BSC. If power alarms are not configured inEAC interface, the FPA interface shall be used and the 'external alarms'shall be mapped as alarm numbers of 7612/7613/7614. The MAINS alamnumber shall be mapped as 7995. If the mains power is lost, the batterybackup system sends a 'mains breakdown' alarm to the BTS, and furtherto the BSC, which then triggers the shutdown procedure.

Benefits

The operation is optimal during both short and long mains breaks. Timersallow executing the shutdown procedure in several phases. Each phasereduces the battery power consumption.

With intelligent shutdown, the operator can define the service level to beapplied on a mains failure to optimise the trade-off between the servicelevel and battery power lifetime. A short mains break will not reduce theservice unnecessarily, whereas during a longer break, the essentialfunctions, such as BCCH or transmission chain, are maintained for as longas possible.

5.2 Remote mode of Nokia Flexi EDGE BTS Manager

The user can control Nokia Flexi EDGE BTS equipment locally via NokiaFlexi EDGE BTS Manager. To minimise the need for site visits, Nokia FlexiEDGE BTS Manager functions can also be accessed remotely.



The user can monitor and test the BTS remotely, by connecting the FlexiEDGE BTS Manager to the BTS remotely via Nokia NetAct™. A PC withthe Flexi EDGE BTS Manager software is used as a user terminal. NokiaGeneral Communication Server (GCS) SW Suite is used for providing bothlocal and remote connections to the BTS.

Figure 3. Nokia Flexi EDGE BTS Manager connected in remote mode

The user can connect to a remote BTS using the Flexi EDGE BTSManager application, via a menu item and/or a toolbar button, or via thecommand line. The user interface of Flexi EDGE BTS Manager informs theuser of the remote connection status when information is being requestedfrom the remote BTS, and when the Flexi EDGE BTS Manager isprocessing received information from a remote BTS. Nokia Flexi EDGEBTS Manager connected in remote mode supports all features availablevia a local connection, except the Control Abis interface (enable/disable)commands.

It is not possible to perform the initial BTS commissioning remotely, but it ispossible to perform subsequent recommissioning or appendcommissioning from the Flexi EDGE BTS Manager in remote mode.

At the BTS, the messages sent from or to the Flexi EDGE BTS Manager inremote mode are re-routed, but handled in the same way as with the localconnection.

BTS

ESMA

BTS

NetAct

BSC

NetActEthernetLAN

Ethernet

BTS Manager,remote

connection

BTS Manager,remote

connection

BTSManager, localconnection

EXxx

ESMA

EXxx



Operability

The alarm 7801 MMI CONNECTED TO BASE STATION indicates whetherthe MMI is connected to the BTS locally (alarm text Local MMI connected) orremotely from Nokia NetAct (alarm text Remote MMI connected).

5.3 BSS10063 Rx Antenna Supervision by ComparingRSSI

The purpose of Rx Antenna Supervision by Comparing received signalstrength indicator (RSSI) is to monitor the Rx antenna condition. Rxantennas can be monitored for major problems by taking a long-termaverage of the difference between the Main Rx RSSI and the Div Rx RSSI.This feature provides continuous antenna supervision for the BTSs, whichhave the Main Rx RSSI and the diversity in use. It also offers an alternativesolution for Tx monitoring in cells that use duplexing. This detects, forexample, antennas with poor voltage standing wave ratio (VSWR) andinadequate feeders.

The monitoring is based on the principle that all received bursts where theRx level of main or diversity branch is above the defined limit value (-100dBm) are accepted as samples and used in the averaging process. Aminimum of 160000 samples in one hour must be collected for the BTS toassume that the results are reliable and therefore could be used to raisean alarm.

The differences of the TRXs connected to the same antennas are countedup, and the average difference for main and diversity antennas iscalculated. If the difference is above the threshold (default value 10 dB),and the number of samples indicate that the results should be reliable, analarm is activated. The threshold default value of 10 dB can be changed bya parameter at the BSC between 3 and 64. The functionality of the featurecan be disabled.

It is still possible that both antennas are damaged simultaneously and thedifference algorithm cannot detect the fault. For this reason, the BSC alsoobserves the assignment and handover success rate.

Note that the RSSI values observed from Nokia Flexi EDGE BTS Managermay not be the same on both of the carriers of a Dual TRX Module. Thedifference between carriers can be greater than 10 dB, depending on theRx level of the calls made on both carriers. If the average uplink Rx level ofcalls (CS/PS) made on Carrier 1 is high compared to Carrier 2, thisdifference can be seen and this is not a problem. It implies that calls onCarrier 1 are being made from mobiles that are near to the BTS, while callson Carrier 2 are being made from mobiles that are relatively far from theBTS. The RSSI difference between two carriers is different from the case



where an RSSI alarm is raised. The alarm is raised because of thedifference in the Rx level of the main and diversity paths of a carrier.However, this alarm is not valid for the comparison done across carriers.Moreover, the comparison of RSSI values across carriers is not valid inNokia UltraSite EDGE BTS, as a TRX in the UltraSite EDGE BTS supportsone carrier only, whereas in the Flexi EDGE BTS, the Dual TRX Modulesupports two carriers.

Benefits

Rx Antenna Supervision by Comparing RSSI can identify antennaproblems without the need for active tests.

5.4 Collection and display of raw RSSI measurements

In addition to the newest and last reliable received signal strength indicator(RSSI) values, the BTS also gathers the raw RSSI results periodically fromthe TRXs. These results are displayed in the Element Manager (EM).

5.5 Settable RSSI sample limit

The number of received signal strength indicator (RSSI) samples, neededfor a valid RSSI calculation, can be configured using the Element Manageraccording to the traffic density. The RSSI sample can be configured tovalues: 80000, 160000 (default), 350000 and 750000. The value 80000 ispreferred when the BTS is located in a rural area and when the trafficdensity is low. The values 350000 or 750000 are preferred when the BTSis located in an urban area and has high capacity utilization. In areas withintermediate traffic density it is preferred to use the default value 160000.

The RSSI sample value may also be configured during the commissioningphase.

5.6 BSS9068 BTS SW management

The BTS software package consists of a master file and severalapplication files. You can update the BTS software by downloading thenew BTS software remotely from the BSC. A site visit is not needed.



Operability

You can download the BTS software to a BCF in the background duringnormal operation, without impact to ongoing traffic or any other operationof the base station. Software downloading is also automatically triggeredafter BCF reset if the System Module does not have the correct BTSsoftware package stored locally (that is, the package set as default for thatparticular BCF at the BSC).

When the BTS software is downloaded from the BSC, the process isoptimised by downloading only those application files which have beenupdated. Application files that are unchanged from those already storedlocally in the current BTS software package are not downloaded. Thisminimises the download time for a new BTS software package.

You can also download the BTS software with Nokia Flexi EDGE BTSManager to minimise BTS boot-up time for new installations. In this caseyou do not need to download the BTS software package from the BSCafter BCF reset.

The downloaded BTS software package is stored in the flash memory ofthe System Module (ESMA). The flash memory of the System Modulecontains two complete BTS software packages to ensure recovery in theevent of a download or start-up failure.

5.7 BSS9067 Runtime diagnostics and BTS alarms

Alarm diagnostics filters alarms, reporting only those alarms that directlyaffect the BTS service level. Only one major or critical alarm per object canbe active at a time.

When the fault causing the alarm has been corrected, or a faulty modulehas been replaced, the alarm is cancelled either manually or automatically.

When the BSC displays a BTS alarm, the alarm text includes a faultreason describing the cause of the alarm. You can use this information introubleshooting. For more information, see Trouble Management of NokiaFlexi EDGE BTS.

5.8 BSS9058 BTS fault recovery

BTS fault recovery minimises the effect of service level faults within theBTS. All objects and interfaces are continuously monitored, andappropriate recovery actions are taken when needed. Alarms are raised toindicate faults, which leads to recovery actions being taken.



For more information on fault recovery and BTS alarms, see TroubleManagement of Nokia Flexi EDGE BTS.

5.9 BSS9063 Abis loop test

The Abis Loop Test verifies the Abis transmission setup and quality.

The Abis Loop Test is carried out automatically by the BSC duringcommissioning. The test can also be carried out manually from the BSC.

Nokia Flexi EDGE BTS provides a test pattern in uplink for the channelsunder test. A group switch loop in the BSC loops the uplink data streamback to downlink where the BTS checks the integrity of the downlinkpattern. The Abis Loop Test can be run on the fixed channels of a TCHallocation and on the channels of a Dynamic Abis Pool. The BTS providesthe related test reports for the BSC.

5.10 BSS9062 BTS supervision

The Nokia Flexi EDGE Base Station monitors and tests itself duringoperation without a separate command.

Continuous monitoring

Both the software and hardware carry out monitoring. Most of themonitoring procedures are so effective that no additional testing to find thefaulty module is needed. The following items are monitored continuously:

. Internal buses of the base station

. Transmission equipment and interfaces

. RF parts

. Mast head amplifiers

. Nokia Flexi Support and Nokia Flexi EDGE Base Station BatteryBackup (MIBBU)

. Combining units (Remote Tune Combiner Module ECxA, DualDuplexer Module ERxA and low-noise amplifiers LNA)

. Converter modules (local and remote EOCAs)

. Temperature (heating and cooling) system of the base station



Operability

. Power supply voltages

. Reference Oven Oscillator

. Dual Transceiver modules (EXxx)

AC mains breakdown

A typical short voltage drop (that lasts less than 20 ms) in the AC mainssupply does not cause any detectable harm to the operation and does notcause an alarm. In case of a mains breakdown, the Nokia Flexi EDGEBase Station cannot send an alarm to the BSC without battery backup(either integrated or external).

5.11 BSS9061 Temperature control system

Nokia Flexi EDGE Base Station monitors its temperature continuously withseveral sensors located in the System Module (ESMA), Dual TRX Module(EXxA), System Extension Module (ESEA), Remote Tune CombinerModule (ECxA) and Optical Converter Module (EOCA).

The BTS controls its temperature with cooling fans to provide as stableoperational conditions as possible. Heating and cooling is controlledgradually depending on the ambient temperature to ensure lowtemperature gradients and noise level.

If the temperature of a module rises too high, a temperature alarm isissued. If the System Module is overheated, the BCF is blocked. If the DualTRX Module is overheated, the associated TRXs are blocked. Powersupply units have their own internal shutdown and recovery in case theyare overheated.

All Flexi EDGE BTS modules operate over full operational temperaturerange without the need for external heaters.

5.12 BSS9060 TRX Test

The total performance of the TRX is tested with a multi-purpose TRX Test.The test covers:

. Digital and RF parts

. RX operation and TX level

. Both RX branches



The TRX test time is approximately 15 seconds.

When the TRX test is carried out according to a regular schedule, it can beused in TRX performance supervision.

Both RX branches are tested separately during the same TRX test. Ifdiversity is not configured, only the main branch is tested.

The TRX Test tests both the Tx and Rx RF paths of the selected TRX viaan uplooped burst to the Air interface, including the Dual TRX Module(EXxx) and Dual Duplexer Module (ERxx) or Remote Tune CombinerModule (ECxx).

The power level during the TRX test is the same as the power level of thebroadcast control channel (BCCH). To avoid unwanted disturbances to theTRXs, the training sequence is not the same as the one normally used.

Figure 4. TRX Test window

All TRXs in the BTS can be tested either remotely from the BSC or theNetAct or locally with Nokia Flexi EDGE BTS Manager.

Note that the TRX test can be performed only in traffic channel (TCH)timeslots. Two free timeslots are needed for the test.

The TRX test is not possible when baseband hopping is used.



Operability

5.13 TRX Loop Test

Nokia Flexi EDGE BTS provides a TRX Loop Test facility. In a TRX looptest, data generated by SW in digital parts of the TRX is looped from theTX to RX side inside the Dual TRX module (EXxx) and the Dual DuplexerModule (ERxx) or the Remote Tune Combiner Module (ECxx), so that theTX and RX chains excluding antennas and antenna feeder cables aretested. Main or diversity paths can be tested.

The BTS checks the looped test data, and the test result is given as BERvalues.

The TRX Loop Test can be performed with GMSK TCH/FS or 8PSKPDTCH/MCS-5 test channels.

5.14 BSS9059 Nokia BTS resets

The operator can reset the Nokia Flexi EDGE BTS objects and moduleslocally with Nokia Flexi EDGE BTS Manager or objects remotely from theBSC or NetAct via Abis.

The reset types are as follows:

. The user can reset the BCF, BTS and TRX separately from the BSCor from Nokia Flexi EDGE BTS Manager. A BCF reset meansresetting all units except the Transmission sub-module (FIxA) - inpractice, it is a site reset.

. The Transmission sub-modules (FIxA) will remain operational duringa BCF reset, to ensure that the transmission cross-connectionsremain operational.

. Each TRX within the Dual TRX Module (EXxA) is reset separately.

. The user can reset the System Module (ESMA) and Dual TRXModule (EXxA) separately from Nokia Flexi EDGE BTS Manager.

. A System Module (ESMA) reset will reset all units including theTransmission sub-module (FIxA).

. A Dual TRX Module (EXxx) reset will reset the HW and SW for bothTRX objects within the Dual TRX Module (EXxA).



5.15 Auto-detection of Site Configuration and RF CableAuto-detection

5.15.1 BSS9056 Auto-detection of Site Configuration

Nokia Flexi EDGE Base Station detects the site configurationautomatically, including all active modules and versions, their serialnumbers and the frequency band used. This information is stored in theflash memory of the System Module (ESMA), and it can be displayed inNokia Flexi EDGE BTS Manager.

The user needs to set the operator-specific settings, such as externalalarm line settings, from the BSC or the NetAct, for example with theRemote MML session.

A possible change in any of the modules or in the configuration causes anautomatic site configuration update in the flash memory of the SystemModule. The configuration is detected both in normal start-up situationsand when extra capacity (more TRXs) is added, modules are removed, ora faulty module is replaced with a new one.

The transmission configuration is part of the site configuration file (SCF),which is stored in the System Module.

There is no auto-detection for the following units/modules: mast headamplifier, power modules, and Wideband Combiner Sub-module (EWxx).

5.15.2 RF Cable Auto-detection

The RF Cable Auto-detection (RFCAD) feature enables the auto-detectionof RF cables connected between the Dual TRX Modules (EXxA) and theDual Duplexer Modules (ERxA) or Remote Tune Combiner Modules(ECxA), when a sector or the BCF comes up after reset, and theprerequisites for RF Cable Auto-detection (which are listed below) arefulfilled.

The configurations for which the RF cabling is automatically detected arelisted in the Nokia Flexi EDGE BTS Commissioning document, AppendixRF auto-detection supported configurations.



Operability

Functionality of RF Cable Auto-detection

ATRX starts to transmit a TX test signal, which the TRX loop module in theDual Duplexer or Remote Tune Combiner Module down-converts to acorresponding RX frequency. The TRX loop switch then sweeps throughall RX ports (both the 'A' and 'B' paths in the Dual Duplexer or RemoteTune Combiner Modules), and the TRXs listen for the received signal (seefigures TRX loop (Dual Duplexer Module) and TRX loop (Remote TuneCombiner Module)).

Figure 5. TRX loop (Dual Duplexer Module)

TX B

TX A

CoRx out

PowerSupply &Digital I/O

RXA1...4

TRX Loop

RXB1...4

ANT A

Ext B

RXA ORXA IRX Signal is sent to

EXxx RX for signallevel measurements

TX signal iscoupled off TXpath

TX Signal isdown convertedto relevant RXfrequency

Ext A

BiasTee/

VS WRalarm

Digitallogic

ANT B

BiasTee/

VS WRalarm

Gain /alarmlogic

DN70292782

Down convertedsignal is sweptthrough all RX paths

EXxx generates TXtransmission



Figure 6. TRX loop (Remote Tune Combiner Module)

The BTS software determines the connectivity between the Dual TRXModule and the Dual Duplexer or Remote Tune Combiner Modules basedon the analysis of the RX measurement reports received from the DualTRX Modules. When the BTS software cannot decide on the presence ofthe RF cables based on the received reports, the BTS software starts oneof the following alarms on the relevant TRX objects: 7606 TRX Faulty (forexample 'EXxx TRX module detected no connection to ERxx DDU via RFcable autodetection') or 7607 TRX Operation Degraded ('EXxx TRXmodule detected only one Rx signal during RF cable autodetection').

The following RF connectivity can be auto-detected:

RX

TX

RX1...3

RX4...6

TX1...6

RXEO

RXEI

Tee

TX / RXANT

EXxx generates TXtransmission

RX Signal is sent toEXxx RX for signallevel measurements

TX Signal isdown convertedto relevant RXfrequency

BiasTee/

VS WRalarm

RX ANT

BiasTee

TX Signal iscoupled offTX path

TRX

Loop

DN70292779

Down convertedsignal is sweptthrough all RX paths



Operability

. Tx cables between the Dual TRX Modules and Dual DuplexerModules.

The Wideband Combiner Sub-modules (EWxx) are included in thedetection process but they are not shown in the Nokia Flexi EDGEBTS Manager as separate objects.

. Tx cables between the Dual TRX Modules and Remote TuneCombiner Modules.

. Main and diversity Rx cables between the Dual TRX Modules andDual Duplexer Modules.

. Main and diversity Rx cables between the Dual TRX Modules andRemote Tune Combiner Modules.

The RF cables for DTRX Optimised configurations can be auto-detected,but the RF cables for the DDU optimised configurations cannot be auto-detected.

Prerequisites for RF Cable Auto-detection

. The Abis connection to the BSC must be available, and the BCFmust be configured at the BSC (that is, the 'BTS_CONF_DATA' isreceived).

. The TRX and BTS object(s) are not locked or blocked (manually orbecause of a blocking alarm). However, in commissioning phase theTRX and BTS object(s) can be locked.

. RF cables were not defined manually during commissioning.

This user selection is stored in the site configuration file (SCF) in theSystem Module's (ESMA) non-volatile memory, and you can check itwith Nokia Flexi EDGE BTS Manager as follows: Commissioning→Fetch SCF from BTS... Detail tab. In the detailed view, locate theline containing 'rfCablingSource', which can have two values:. 'AUTODETECTED': RF Cable Auto-detection was used during

commissioning or. 'SCF': RF cabling was entered manually during commissioning

(which means that RF Cable Auto-detection was not usedduring commissioning and cannot be used later on either)

If all three prerequisites are met:

. the RF Cable Auto-detection is run, when:



. In the commissioning phase RFCAD will be run whenBTS_CONF_DATA is received (concerns also the lockedTRXs).

. The receive of new BTS_CONF_DATA in an alreadycommissioned site is not enough to start RFCAD. If there arechanges to the configuration: added/deleted TRXs or sectorsand then BTS/BCF reset for affected sectors, then RFCAd willbe done.

. a BTS or BCF reset is given, and the previous RF Cable Auto-detection on a BTS (sector) had partially failed.

. a BTS or BCF reset is given (from the Flexi EDGE BTSManager) with the 'With RF detection' option (the so-called‘forced RFCAD’).

5.16 Optical Converter Module (EOCA) autodetectionand runtime polling

All Optical Converter Modules (EOCA) are autodetect. The BTS Manageris able to obtain information about the local and remote EOCA(s), EOCApair hot-insertion and RF Modules (Dual TRX Module and Dual DuplexerModule) connected behind remote EOCA at times of BTS startup. TheEOCAs are always detected in pairs (local and remote) provided that atleast one Dual TRX Module is connected behind the remote EOCA.

Once the EOCA Module(s) are detected successfully, they are polledperiodically to get alarm statuses. If an EOCA Module fails to respond tothe status poll request the BTS starts a respective alarm.

5.17 BCCH antenna VSWR measurement

Nokia Flexi EDGE BTS provides broadcast control channel (BCCH)antenna line supervision by means of voltage standing wave ratio (VSWR)monitoring in the Dual Duplexer Module (ERxA). If the traffic channel(TCH) TRX(s) are combined to the same antenna line with the BCCH TRX,those TRXs (and their traffic) are also covered. Other TCH TRXs (that is,the ones connected to the TCH-only antenna lines) are not supervised bythe BCCH antenna VSWR monitoring feature.

During commissioning, the user can set the VSWR minor and major alarmlimits for each antenna line separately. The minor limit can be set between1.5...2.9:1 (that is, with a return loss 14.0 - 6.2 dB) and the major limitbetween 2.7...3.5:1 (6.8 - 5.1 dB). The default limits on the Nokia Flexi



Operability

EDGE BTS Manager are 2.1:1 (minor) and 3.1:1 (major) which converts to9 dB (minor) and 5.8 dB (major) return loss (RL) respectively. At the end ofthe commissioning process, the values are stored in the site configurationfile (SCF) in the System Module's (ESMA) non-volatile memory.

During normal BTS operation, the Dual TRX Module (EXxA) sends apolling request to the Dual Duplexer Module every few seconds. The DualDuplexer Module responds with a message containing the return lossvalues for both antenna paths (A and B). The Dual Duplexer Module isable to report the return loss reliably if the TX (BCCH) power in its TxA orTxB input exceeds approximately +32 dBm. The BTS software convertsthe reported return loss values to VSWR values, and compares them withthe minor and major limits found in the site configuration file. If severalconsecutive polls show that either the minor or the major threshold isexceeded, and the antenna line carries the BCCH, the alarm is consideredto be real, and is reported to the BSC and Nokia Flexi EDGE BTSManager. If the reported VSWR exceeds the minor limit, the 7607 'TRXoperation degraded' alarm is activated. If the VSWR condition thenimproves, the 7607 alarm is automatically cancelled. If the VSWR exceedsthe major limit, the 7606 'TRX faulty' alarm is activated, and the affectedTRX objects are blocked. Both alarms are handled as TRX object alarms,therefore alarms are raised for all TRXs that have their TX path on theaffected antenna line as defined in the site configuration file.

Typical causes for a bad VSWR are broken cables, broken connectors,and the ingress of water in the antenna cable path.

If a TX cable carrying the BCCH is accidentally plugged out between theDual TRX (EXxx) and the Dual Duplexer Module (ERxA) or the RemoteTune Combiner Module (ECxA) and the Dual TRX (EXxx) Module, thetransmission will cease shortly and the 7606 'TRX faulty' alarm is set off forall TRXs located in the involved sector (the Dual TRX is not the onlymodule infected by a removed TX cable). In order to cancel the alarm,object resets need to be given several times in the involved sector until theBSC moves the BCCH to an another location within the sector (providedthat the sector includes at least two Dual TRX Modules).

5.18 48 V DC input voltage supervision

Both the System Module (ESMA) and the System Extension Module(ESEA) supervise the 48 V DC input voltage continuously.



When the input voltage drops below 39.5 V DC or raises above 58 V DC,all the Dual TRX Modules (EXxA) and Remote Tune Combiner Modules(ECxA) are shut down to protect their hardware. The Dual TRX Modulesare again powered up when the input voltage raises up to 40 V DC ordrops below the 57.5 V DC range.

Hysteresis and timeouts are used to avoid toggling in the border voltages.

5.19 Antenna Hopping

Antenna Hopping is a further improvement for the performance of RF orBB hopping. In antenna hopping, also the BCCH frequency is fully hoppingbetween 2 or more antennas.

Antenna Hopping enables the TRXs in an RF hopping BTS to transmitwith all the TX antennas in the BTS. Antenna Hopping uses the existingbaseband (BB) hopping functionality in the BTS.

Antenna Hopping can be used either with or without the RF hoppingfeature. With RF hopping, cyclic and all random frequency hoppingsequences can be used together with Antenna Hopping. Antenna Hoppingpattern will be automatically optimised based on the frequency hoppingsequence. The BCCH TRX is included in the Antenna Hoppingconfiguration, that is the BCCH transmission is moved from one antenna toanother antenna (TRX).

With Antenna Hopping, it is possible to achieve space diversity to theregular RF hopping configuration, which means that there is a distancethat separates two or more transmitting antennas providing uncorrelatedsignals. At the MS, a separation of half a wavelength is the minimum forobtaining uncorrelated signals. At the base station frequency, the antennaheight and antenna spacing make the correlation efficient.

Restrictions

The following functionalities cannot be used simultaneously with AntennaHopping:

. BB hopping or DFCA hopping in the same BTS

. Baseband hopping

. Remote Tune Combiner (RTC) in the same BTS

Antenna Hopping is OFF in the BTS



Operability

. when TRX(s) are down

. if the number of working TRXs decreases below 2 TRXs per BTS

When Antenna Hopping is in use the following tests are not possible:

. the TRX test

. the TRX loop test

The minimum configuration for Antenna Hopping is two TRXs/cell whereboth TRXs are used for Antenna Hopping.

Benefits

The Antenna Hopping feature helps to avoid network level interferenceand link level frequency selective fading.

With the Antenna Hopping feature, the user can achieve in average 2 dBgain on the link level. With low antenna correlation, Antenna Hopping cangain 1.5 to 4 dB depending on the mobile speed (typical urban, 3 to 50 km/h, no FH) compared to a single antenna.

With Antenna Hopping, it is possible to gain better network level spectralefficiency on the BCCH layer. In a very narrow band environment (3.6MHz), better network capacity can be achieved by tightening the BCCH re-use (for example from 5/15 to 4/12) without an extra TRX). By tighterBCCH re-use, more frequencies can be used in the hopping traffic layer,thus providing better capacity for narrow band networks.



6 Site solutions

6.1 BSS10046 Multi BCF Control

Multi BCF Control allows the combination of several BTSs into one logicalcell, enabling the operator to increase the capacity of a cell whilemaintaining the maximum spectral efficiency. Multi BCF Control increasesthe cell capacity for Nokia Flexi EDGE BTSs to 36 TRXs while requiring noextra BCCH. Multi BCF also provides a path for site expansion from NokiaUltraSite EDGE BTS to Nokia Flexi EDGE BTS.

Multi BCF Control requires that BSS9055 Clock Synchronisation betweenbase stations, or BSS10069 Synchronised BSS is used.

The operator can arrange base stations so that the TRXs in different basestations (operating on the same frequency band) can serve the same cellwith a single BCCH. At the base station site, the operator needs to makesome installations, for example synchronisation is needed between thebase stations. All the base stations will have a separate O&M link to theBSC. At the BSC, a SEGMENT (SEG) object must be used to set all theBTS objects sharing the same BCCH.

Figure 7. Multi BCF configuration

Multi BCF cell (= SEG)

f1 f2 f3

f4 f5

UltraSite TRX group

Flexi TRX group



Site solutions

6.2 BSS9055 Clock Synchronisation between BaseStations

Clock Synchronisation between Base Stations enables synchronoushandovers between base stations. The sectors defined to different basestations can use common hopping frequencies with RF hopping, whichincreases the channel capacity. The maximum site configuration is nineNokia Flexi EDGE BTSs in a chain.

The Nokia Flexi EDGE Base Station has an external clock interface thatcan be used to synchronise the air interface between several Nokia FlexiEDGE Base Stations located on one site.

When several Nokia Flexi EDGE Base Stations are synchronised, themaster base station (master BTS) functions as the frame clock source tothe slave BTSs. The master BTS transmits the frame clock and framenumber signals to the external clock line, while the other BTSs (slaveBTSs) receive these signals. The slave BTS uses the received frame clocksignal as a reference clock signal to adjust its main frequency source. Themaster BTS uses the reference clock signal derived from the Pulse CodeModulation (PCM) signal.

It is possible to synchronise a Nokia Flexi EDGE Base Station to a NokiaUltraSite EDGE BTS to serve the adjacent sectors. In this case the clockmaster is always a Nokia UltraSite EDGE BTS.

Physical properties

The maximum cable length for the total system is 100 metres. Thesynchronisation chain between the BTSs is made using RS-485connection for the transferred clock signals.

Synchronisation recovery

If there is a failure in the synchronisation between the base stations, theslave BTS generates an alarm and the BSC then blocks all TRXs of thealarming BCF. When the fault disappears, cancellation to the alarm is sentto the BSC. The BSC then unblocks the TRXs under the alarming BCFobject.

Fast tuning

. If the clock reference is taken from Abis:



If the BTS is being commissioned, the fast oven-controlled crystaloscillator (OCXO) tuning is executed for the maximum duration of 8.6seconds. The target accuracy is 0.02 ppm. The adjustments can be 10times larger than in normal tuning. After fast tuning, the BTS starts normaltuning, and allows the BTS configuration to be completed.

. If the clock reference is taken from an external synchronisationsource (other BTS or LMU):

If the BTS is being commissioned, the fast OCXO tuning is executed for anindefinite duration until the target accuracy of 0.02 ppm is met. Typically,the external clock reference is stable, therefore the fast tuning iscompleted in 4.6 seconds (two rounds). The first round is for getting thereading and for adjustments, and the second round is for validating that therequired accuracy is met. The adjustments can be much larger than innormal tuning. After fast tuning, the BTS starts normal tuning, and allowsthe BTS configuration to be completed.

Normal tuning

With Abis as reference, the digital-to-analogue converter (DAC) wordadjustment may occur every 20 minutes. The purity of Abis is monitoredcontinuously, and the adjustment is only performed if the purity is goodenough.

With an external clock as reference, the DAC word adjustment may occurevery 20 minutes. The presence of the external clock source is monitored,the purity is not. When the external clock is present, the adjustment ismade.

With both clock sources, the current DAC word is written as a newcalibrated DAC word, if the current DAC word eventually drifts far enoughfrom the calibrated DAC word. This ensures that in later start-ups (in anyenvironmental conditions), the BTS starts immediately with a value asaccurate as possible, and the C-plane and U-plane signalling and trafficremain undisturbed.

6.3 BSS10069 Synchronised BSS

With Synchronised BSS, all the clocks of the different sites in the networkare synchronised, so that the GSM frame timing is aligned between allsites.

This is done by using a Location Masurement Unit (LMU), which gets aGPS time reference, and uses this to generate clock signals for the BTSs.



Site solutions

Syncronising all BTS sites in the network minimises timing differencesbetween TDMA bursts of different sites. That significantly improvesperformance of Interference Rejection Combining and DFCA. The benefitsare:

. Improved quality (higher data throughput, lower frame error rate(FER))

. Possibility of tighter frequency reuse

. More effective cell re-selection and handover processes

. More accurate MS locationing functionality

6.3.1 BSS20371 BSS Site Synchronisation Recovery Improvement

BSS Site Synchronisation Recovery Improvement is an enhancement toBSS11073 Recovery for BSS and Site Synchronisation. With BSSSynchronisation Recovery Improvement, the BTS site continues in theBSS synchronised service even if the GPS coverage is lost for up to 24hours. The BTS site also continues in the BSS synchronised servicethroughout an LMU software update.

The transmission link(s) to the BTS site meet the Jitter and Wanderrequirements of ANSI T1.403 for T1 links, or ITU G.823 for E1 / 2048 kbit/sec hierarchy links.


Improved BSS Synchronisation Recovery is used in any networks whichuse BSS Synchronisation.

6.3.2 BSS11073 Recovery for BSS and Site Synchronisation

The main purpose of Recovery for BSS and Site Synchronisation is to giveautomatic recovery for BSS Synchronised sites (sites with LMU) if the BSS20371 Site Synchronisation recovery improvement is not used.

. when the Location Measurement Unit (LMU) clock signal is lost, toget the chained BTS cabinet (site) into unsynchronised mode

. when the LMU clock signal is again available, to return the chainedcabinet back into synchronised mode

Recovery for BSS and Site Synchronisation also offers synchronisationrecovery for a Multi BCF site using BSS9055 Clock Synchronisation.



When the BTS chain is defined in the BSS radio network database,Recovery for BSS and Site Synchronisation automates the recovery if theBTSs in the chain are synchronised and the clock signal is lost andregained. On the other hand, if the chain is not defined or the BSS or Sitesynchronisation of the chain has not been activated, the sites need to belocked and unlocked in the correct order to enable systemsynchronisation. The BSC receives the information for recovery from Q1and BTS alarms.

Recovery for BSS and Site Synchronisation can be used together with theDynamic Frequency and Channel Allocation (DFCA) when the LMU isdefined as a clock source in the BSS radio network database and the BCFis in synchronised mode, and with the Multi BCF configuration, providedthat all the unlocked BCFs are defined to the same chain operating insynchronised mode.

For a Flexi EDGE BTS chain, the maximum number of BTSs is nine.

Figure 8. Synchronised BSS example in Flexi EDGE BTS chain

The BSS is synchronised by a Global Positioning System (GPS), that is,LMUs are installed to every site with GPS antennas. The clock source is aGPS satellite via the LMU. When the LMU feeds the clock, all BTSs areworking as slaves. When the LMU clock feed is lost, the BSC starts atimer. The synchronised operation continues uninterrupted based on theBTS internal clock. If the BSC timer expires, the first BTS in the chain

BSC

LMU(master)

BTS(Flexi)(slave)

IN OUT

Abis

FN Offset

Q1

FN, FCLK

BTS2(Flexi)(slave)

IN OUT

BTS3(Flexi)(slave)

IN OUT

FN, FCLK FN, FCLK



Site solutions

becomes a clock master and starts supplying the clock signal to the otherBTSs. The BTS synchronisation status indication in the BSC is changed to'unsynchronised'. When the LMU clock is recovered, the BTS becomessynchronised again.

Recovery for BSS and Site Synchronisation supports the following BTSgenerations and SW, when the chain is defined:

. Flexi EDGE BTS with EP1

. UltraSite EDGE BTS with CX4 or later

. When BSS synchronisation configuration is used, LMU SW 4.3 orLMUB SW 1.0 or later is required with the feature

Benefits

Automatic recovery for the loss of LMU clock, when the BTS chain isdefined in the BSS radio network database:

. Automatic BSC-controlled recovery to unsynchronised operation

. Automatic BSC-controlled return to synchronised operation

. Timeslot offset parameter sending to LMU

. BTS synchronisation configuration and mode information availablefrom the BSC by MML and NetAct

6.4 Operating bands

Nokia Flexi EDGE BTS supports the following operating bands:

. GSM 800

. GSM 900 (including E-GSM and P-GSM)

. GSM 1800

. GSM 1900

Dual and Tri Band Common BCCH

Common BCCH allows the combination of two or more sectors into asingle logical cell, with a single BCCH carrier. With common BCCH sectorsin different frequency bands such as 900/1800 MHz (or 800/1900 MHz, or800/1800 MHz) can be configured with a common BCCH carrier.



The main advantages of the common BCCH functionality are:

. Improved trunking gain

. Use of signalling channels is optimised by sharing them betweenbands

. Tighter reuse of all carriers in the non-BCCH bands

. Better call quality because of decreased number of handovers

To ensure proper operation of the network, take into account issues relatedto the difference of propagation between the different bands whenperforming cell planning.

Figure 9. Common BCCH configuration

Frequency hopping between bands in the same sector is not supported.

6.5 BTS2043 BTS External Alarms and Controls (EAC)

External Alarms and Controls (EAC) signals can be defined to the BTS.

Benefits

The external alarms and controls allow alarms to be sent from externalequipment attached to the BTS, and allow control of external equipmentattached to the BTS.

External Alarms caused on the site, such as the intruder alarm, are sent tothe NetAct via the Abis. The alarms are TTL level signals, all referred to 5V. The operator can define whether an alarm is raised when the alarminput line is grounded or disconnected from the ground potential (this isknown as alarm polarity). This allows more flexibility for the alarmingdevice.

Common BCCH cell

f1 f2 f3

f6 f7 f8

f4 f5

PGSM 900 TRX group

EGSM 900 TRX group

GSM 1800 TRX group



Site solutions

The External Controls allow the user to control external equipmentremotely from the BSC. The External Controls are of open-collector type.

The EAC settings (such as name, alarm polarity, control state) are definedat the BSC. The EAC names can be viewed at the BSC.

Restrictions

There are 24 user-definable external alarms and 6 user-definable externalcontrols. The System Module (ESMA) provides 12 alarm inputs and 6control outputs. Another 12 alarm inputs are available with the optionalFlexi System External Alarm Module (FSEB).

6.6 BTS2020 RX antenna diversity

Receiver diversity (spatial diversity) improves the uplink performance. It isavailable as operation software for all configurations having at least twoantennas in a sector. Two RF signals are demodulated jointly using aninterference rejection combining algorithm, which increases tolerance tointerference. Sensitivity is improved, particularly in fading scenarios.

Diversity is defined for every sector separately from the BSC.

6.7 BTS configurations

Nokia Flexi EDGE BTS is optimised for high capacity as well as highcoverage for macrocellular applications. It also enables evolution paths byproviding a flexible expansion capability. A configuration of up to 24 TRXsis supported in a Nokia Flexi EDGE BTS, but only with Dual DuplexModules (ERxA). With Remote Tune Combiner Modules (ECxA), themaximum number is 18 TRXs. When the number of TRXs is close to 24,the combining usually has to be either 2-way or 4-way. Also three to sixsectors are required.

Nokia Flexi EDGE BTS offers flexible combining options to increase theBTS capacity without a need to increase the number of BTS antennas.There are also combining options to maximise the cell coverage orcapacity.

For details of Nokia Flexi EDGE BTS configurations, see HardwareConfiguration Reference Guide and Nokia Flexi EDGE BTS ProductDescription in Nokia Flexi EDGE BTS Product Documentation.



6.7.1 Upgrade-optimised configurations

An upgrade-optimised Flexi EDGE BTS configuration with a 1-way or 2-way diversity can be installed in a stack, wall, pole, in Flexi Cabinet forIndoor (FCIA) and Flexi Cabinet for Outdoor (FCOA). In an upgrade-optimised configuration, the Dual TRX Modules (EXxA) and Dual DuplexerModules (ERxA) are allocated to one sector. In case of odd configurations,the number of Dual TRX Modules and Dual Duplexer Modules can be oneor two more than could be built in a cost-optimised way. An example 3+3+3 configurations with 2-way diversity requires six Dual TRX Moduleswhere three carriers are unconfigured.

6.7.2 Cost-optimised configurations

A cost-optimised 3+3 Flexi EDGE BTS configuration with 2-way diversitycan be installed in a stack, in Flexi Cabinet for Indoor (FCIA) and FlexiCabinet for Outdoor (FCOA).

For creating this configuration, the following modules are needed:

. one System Module (ESMA)

. three Dual TRX Modules (EXxA)

. two Dual Duplexer Modules (ERxA)

. four Wideband Combiner Sub-modules (EWxx).

Also other cost-optimised Flexi EDGE BTS configurations can be built: 3+3+3 (2-way combining), 5+5 (4-way combining) with 2-way diversity. Withcost-optimised configurations, one Dual TRX Module is split between twosectors, and its Rx1div and Rx2div connectors are used to make 2-waydiversity functional.

6.8 Nokia Flexi EDGE BTS Feederless and DistributedSite concept

Nokia Flexi EDGE BTS Feederless and Distributed Site Solutions refer toa situation where the System Module (ESMA) and Dual TRX Modules(DTRX) are installed apart from each other. The Optical Converter Module(EOCA) is used at both ends of the optical fibre for interfacing the SystemModule/Dual TRX Module. The bus cable between the modules is optical.

The benefits of the Feederless and Distributed Site Solutions compared toa traditional BTS site are listed below:



Site solutions

. Overall site RF performance is better compared to antenna feedersinstallation (the gain can be 2...5dB).

. The solutions open easier, new and optimized installationpossibilities especially in difficult places.

. There is no need for mast head amplifiers.

Nokia Flexi EDGE BTS Feederless and Distributed Site solutions utilisevarious power distribution solutions. DC feed to the feederless ordistributed site is provided either by a Nokia Siemens Networks powersystem or 3rd party products. The input for the Optical Converter Module isfloating 48 VDC. There are the following basic power supply alternativesfor the BTS site and its modules:

. Flexi Power Module (FPMA) or MIBBU concept with a site supportmodule, batteries, and cabinet

. FPMA installed near the Dual TRX Module

. 3rd party AC/DC system (must meet the ETSI 300 132-2 standard)

6.8.1 Feederless site

In the feederless site solution, the distance between the System Moduleand the Dual TRX Module can be up to 150 m. The feederless site solutionis typically used either on a rooftop BTS site as show in figure Feederlessrooftop site or as mast head BTS site. In both cases the Dual TRX Module(EXxx) can be installed very close to the antenna. This enables connectingthe Dual TRX Module to the antenna with a short jumper cable.

When DC is fed from the DC power system to the Dual TRX Module, themaximum distance is 100 m (measured from the power system equipmentto the Dual TRX Module input). The BTS site can be either DC or ACpowered (this concerns all the modules that require 48 VDC). In the lattercase, an AC/DC converter (either the FPMA or a 3rd party converter) isrequired and the maximum length of the optical cable to be used is 150 m.

For information on installation distances see the Installing Feederless FlexiEDGE BTS Site document.



Figure 10. Feederless rooftop site

DN70471877

Sector 1:DTRX + System Module +2 Opt. Converters

Sector 2:DTRX +Opt. Converter

Sector 3:DTRX +Opt. Converter



Site solutions

Figure 11. Feederless masthead site

Optical cable installation between the System Module and the Dual TRXModule can be done with the following alternatives:

. One 50 or 100 m Nokia optical cable.

. By splicing and cutting Nokia optical cables on sites where a certainoptical cable length is required.

. By connecting two 50 m and/or 100 m (for 150 m) Nokia cablesusing a multimode adapter together with a locally sourced IP55 box.

. Other cable lenghts are available for special order (10 m, 20 m, 30m, 40 m, 75 m). Only NSN optical cables are allowed.

If a distance longer than 150 m is needed, see Distributed site.

DN70470796

Fiber optics linkEthernet linkDCsupply

DC

System Module

Optical Converter

Dual TRX Module

Dual Duplexer Module

Dual TRX Module


Dual TRX Module


Optical Converter



Figure 12. Optical cable installation alternatives

The Optical Converter Module provides Overvoltage protection byinduction or indirect lightning (Class II).

6.8.2 Distributed site

In the distributed site solution, the distance between the System Moduleand Dual TRX Modules can be up to 10 km. The existing optical fibres canbe utilised and equal benefits are possible in the feederless site conceptutilised. The Optical Converter Modules can be attached to the existing

OpticalConverter

OpticalConverter

OpticalConverter

AlternativeNokia IP55 OpticalMultimode Cable

AlternativeCuttingandSplicing

AlternativeUse ofMultiModeadapter

Optical ConverterModule

SFP

IP55protection

MultiModeAdapter

IP55protection

IP55 IP55 IP55

DN70470839

IP55 SFPIP55 SFPIP55

System ModuleSystem ModuleSFP

System ModuleSFP SFP





Site solutions

optical fibre network by using a 2 m single mode optical cable that hasIP55 protection in the Optical Converter Module end of the cable. Singlemode components and single mode transceivers are used in OpticalConverter Modules.

The power distribution to the Dual TRX Module is local and can be eitherDC or AC (an FPMA next to the RF Module or a 3rd party system). OpticalConverter Modules have integrated Class II overvoltage protection, so noexternal OVP is required when DC input is used. In case AC input is used,overvoltage protection has to be carried out locally. The distributed siteconcept is illustrated in the following figure.

Figure 13. Distributed site concept (e.g. as a part of a BTS hotel)

6.9 Distributed BTS with Optical Converter modules(EOCA)

Distributed BTS concept

With Flexi EDGE SW release EP1.1 you can take advantage of the NokiaDistributed BTS concept. With the distributed BTS, certain parts of theBTS can be physically separated from each other. On a roof site, forexample, the radio parts can be located at the corners of the building and

Local EOCA

System Module

Local EOCA

Local EOCA

Singlemodeoptical

Singlemodeoptical

Singlemodeoptical

*optionalDN70461251

Remote Head

Sector Module

Remote EOCA

Dual TRX Module*

Remote Head

Sector Module

Remote EOCA

Dual TRX Module*

Remote Head

Remote EOCA

Dual TRX Module*



the common parts (O&M, transport, BBU) can be located in the middle ofthe roof (or with one of the radio parts at a corner). This can lower the siteinvestment costs whilst improving the coverage, as the total length ofantenna feeder line required is reduced.

Optical Converter modules (EOCA)

To implement the Distributed BTS concept, pairs of Optical Convertermodules (EOCA) act as a single optical link for up to three Dual TRXmodules (EXxA). The optical links allow the separation of System module(ESMA) and Dual TRX modules (EXxA). The separated Dual TRXmodules (EXxA) then work as remote radio parts.

To provide the optical link, two Optical Converter modules (EOCA) areused together as a pair. One Optical Converter module (EOCA) isconnected via 1, 2 or 3 BUS ports of the System module (ESMA), and thismodule is known as the Local EOCA module (LEOCA); the second OpticalConverter module (EOCA) of the pair is equipped near the antennas and isknown as the Remote EOCA module (REOCA). The Remote OpticalConverter module (REOCA) then connects to up to 3 Dual TRX modules(EXxA) using BUS ports. The Local Optical Converter module (LEOCA)and Remote Optical Converter module (REOCA) are connected togetherwith an optical link.

Both the Local Optical Converter module (LEOCA) and Remote OpticalConverter module (REOCA) require a 48V input source. The RemoteOptical Converter module (REOCA) provides power for up to 3 Dual TRXmodules (EXxA) via the PWR ports of the Remote Optical Convertermodule (REOCA). Intelligent shutdown and BTS Manager power controlfeatures still function with remote Dual TRX modules (EXxA).

Warning

The PWR connections of the System module (ESMA) and LocalOptical Converter module (LEOCA) should NOT need to beconnected together. Only the BUS connections for the Dual TRXmodules (EXxA) need to be connected to the Local OpticalConverter module (LEOCA).

Display of Optical Converter modules (EOCA) with the Nokia FlexiBTS Manager

See the following figure for an example of Optical Converter modules(EOCA) displayed in Nokia Flexi EDGE BTS Manager Base Station view:



Site solutions

Figure 14. EOCA displayed in BTS Manager Base Station view

In the above example, two pairs of Optical Converter modules (EOCA) arepresent. Pair 1, identified as LEOCA1 and REOCA1, connect the Systemmodule (ESMA) to EXDA1 and EXDA2. Pair 2, identified as LEOCA2 andREOCA2, connect the System module (ESMA) to EXDA3 and EXDA4.Dual TRX modules EXDA5 and EXDA6 are connected directly to theSystem module (ESMA) as per normal BUS connections.

A single pair of EOCA modules can connect up to 3 Dual TRX modules(EXxA). To display the connections in the Base Station view of the BTSManager, the EOCA pairs may appear 1, 2 or 3 times in the view. To makeit easy to see which pairs are displayed multiple times, each pair has a



unique color border around the LEOCA and REOCA modules in thedisplay. In the example screenshot above, Pair 1 (LEOCA1 and REOCA1)are shown with a dark blue-green color border. Pair 2 (LEOCA2 andREOCA2) are shown with a light green color border.



Site solutions



7 Basic GSM operation

7.1 Basic GSM features

Nokia Flexi EDGE BTS supports the following basic GSM channelcombinations:

. Combined broadcast control channel (BCCH) including. frequency correction channel (FCCH). synchronisation channel (SCH). common control channel (CCCH). standalone dedicated control channel (SDCCH/4). slow associated control channel (SACCH/C). random access channel (RACH)

. Non-combined broadcast control channel (BCCH) including. frequency correction channel (FCCH). synchronisation channel (SCH). common control channel (CCCH). random access channel (RACH)

. Standalone dedicated control channel (SDCCH) including. Standalone dedicated control channel (SDCCH/8). Slow associated control channel (SACCH/C)

. Full rate speech (TCH/FS, TCH/EFS, TCH/AFS) with. Slow associated control channel (SACCH/T). Fast associated control channel (FACCH)

. Half rate speech (TCH/HS, TCH/AHS) with. slow associated control channel (SACCH/T). fast associated control channel (FACCH)

. Full rate circuit-switched data (TCH/F24, TCH/F48, TCH/F96, TCH/F144) with



Basic GSM operation

. slow associated control channel (SACCH/T)

. fast associated control channel (FACCH)

7.2 BSS6071 Enhanced Full Rate Codec

Enhanced Full Rate Codec (EFR) uses the existing GSM 900/1800 fullrate channel coding but provides a considerably better performance in allchannel conditions. Moreover, in good channel conditions, the codecensures equal or better quality than Adaptive Differential Pulse CodeModulation (ADPCM).

The EFR can coexist with Half Rate (HR) or Full Rate (FR) 'dual codec'.

7.3 BTS2023 Downlink and uplink DTX

Discontinuous transmission (DTX) is a mechanism allowing the radiotransmitter to be switched off during speech pauses. This feature reducesthe power consumption of the transmitter, which is important for mobilephones, and decreases the overall interference level on the radio channelsaffecting the capacity of the network.

The DTX function is supported both in downlink and uplink for the followingspeech channels: TCH/FS, TCH/EFS, TCH/AFS, TCH/HS, and TCH/AHS.

7.4 BTS2503 Compressed Abis timeslot allocation

In traditional transmission solutions, some capacity is left unused,especially in the case of BTSs with one TRX, because one radio interfacetime slot is always used for the broadcast control channel (BCCH). Thecompressed Abis time slot allocation makes it possible to use this capacityfor TRX signalling. This slot can 'steal' the traffic channel (TCH)transmission slot, which leaves capacity for six full rate TCHs or twelvehalf rate TCHs for that TRX.

In environments where it is not necessary to use the full traffic capacity of aTRX, compressed Abis time slot allocation offers an ideal solution for usingthe transmission medium more efficiently. With this configuration, it ispossible to fit 15 TRXs to one 2 Mbit/s PCM.



7.5 BTS2067 Fast Associated Control Channel(FACCH) Call Setup

With Fast Associated Control Channel (FACCH) Call Setup, it is possibleto establish a call without using a stand-alone dedicated control channel(SDCCH). A traffic channel (TCH) is set to 'signalling only' and switchedover to normal speech operation when needed. FACCH Call Setup is foremergency calls only.

7.6 BSS7036 Dynamic SDCCH Allocation

Dynamic Stand-alone Dedicated Control Channel (SDCCH) Allocationallows the SDCCH resources to be configured according to the actualSDCCH traffic situation of a cell. When the BTS temporarily needs greaterSDCCH capacity than normal, the BSC configures the idle traffic channel(TCH) resources for SDCCH use. For an example of this, see the figurebelow. A maximum of two additional SDCCH/8 can be configured. Whenthe SDCCH congestion situation is over, the extra SDCCH resources areconfigured back to TCH resources. Dynamic SDCCH Allocation can beused with both combined and non-combined Broadcast Control Channel(BCCH).

The BTS only needs to be configured to the minimum static SDCCHcapacity sufficient to handle the normal SDCCH traffic.

Figure 15. Dynamic SDCCH allocation

TCH(busy)

TCH TCH(busy)

TCH(busy)

SDCCH/8

BCCH SDCCH/8 TCH(busy)

TCH(busy)

TCH(busy)

TCH(IDLE)

TCH(busy)

TCH

TRXwith staticSDCCH/8

New TRXconfiguration

with additionalSDCCH/8

SDCCH congestion triggersdynamic allocation of SDCCH for free FR RTSL

BCCH SDCCH/8 TCH(busy)

TCH(busy)



Basic GSM operation

An extra SDCCH resource is allocated only when the existing SDCCH isfully loaded. When the dynamic SDCCH radio resource is totally freeagain, it is immediately reconfigured for TCH use. Thus, the maximumnumber of TCHs is always in use depending on the actual need of theSDCCH resources at each moment.

Dynamic SDCCH Allocation benefits traffic cases in which signalling is theonly transmission to the network, for example Short Message Service(SMS) traffic and location updates. In some special places, such asairports and stations, the location updates can produce sudden short-termSDCCH congestion. With Dynamic SDCCH Allocation, this can behandled without any need to configure extra permanent SDCCH capacity.

7.7 BTS2024 Synthesised frequency hopping

Synthesised frequency hopping is available for configurations that have atleast two TRXs per sector. Synthesised frequency hopping enables allTRXs to change frequencies in successive timeslots, so that the carrierscan hop at many different frequencies in quick succession. Both randomand cyclic hopping can be used. The maximum number of frequencies perBTS site is 64. The number of frequencies can be greater than the numberof TRXs.

Note that the BCCH carrier must remain at a fixed frequency and at a fixedpower level to enable the MS to measure the signal strength.

7.8 BTS2013 Baseband Frequency Hopping

In Nokia Flexi EDGE BTS, the Dual TRX Modules are interconnectedthrough a Gigabit Ethernet L2 switch to facilitate baseband hopping. Bothrandom and cyclic hopping can be used for baseband hopping. Thenumber of frequencies used in the baseband hopping frequency hoppingsequence is the same as the number of carriers in the sector. Basebandhopping is allowed for all BTS configurations.



7.9 BTS2037 Air interface measurement pre-processing

The measurement results for the active channels may be averaged for theTRX. This option is useful when 16 kbit/s signalling is used because itreduces the capacity needed on the Abis link. The averaging period maybe set to consist of 1 - 4 SACCH multiframes. Both uplink and downlinkmeasurements are averaged. As a result, the BSC receives ameasurement report once at the end of the averaging period rather thanafter every SACCH multiframe.

7.10 BTS2012 BTS time base reference from PCM

The PCM clock is used as a reference when tuning the long-term accuracyof the BTS internal clock. The requirement for the accuracy is 0.015 ppm inorder to meet the GSM requirement (0.05 ppm) for the clock signalaccuracy in the Air interface.

7.11 BTS2133 Short Message Service (SMS) point-to-point

Nokia Base Station supports the short message service (point-to-point) forboth mobile originating and mobile terminating calls.

7.12 BTS2033 Short message cell broadcast

The short message service (cell broadcast) defined in the GSMrecommendations is supported.

7.13 BSS6025 Short Message Service Cell Broadcastwith Discontinuous Receiving (SMS-CB DRX)

SMS-CB DRX enables phase-2 Mobile Stations (MSs) to receive only theneeded blocks of the CBCH (Cell Broadcast Channel). This decreasesbattery consumption.



Basic GSM operation

The BSC has a user interface for SMS-CB (Short Message Services CellBroadcast) and it stores CB messages in the BSS. After the BTSinitialisation, the BTS operates in non-DRX (Discontinuous Receiving)mode until SMS-CB DRX is activated in the BSC. When SMS-CB DRX isemployed, the BTS starts transmitting Schedule Messages to the cell area.A Schedule Message includes information about a number of immediatelyfollowing consecutive CB messages, planned for that cell. The timebetween two Schedule Messages is called the Schedule Period. TheSchedule Period is one minute (see the figure below).

The MS starts operating in DRX mode after the power up when it hasreceived the first Schedule Message. If the MS does not receive aSchedule Message, it has to read at least the first block of each CBmessage.

Figure 16. SMS-CB DRX Schedule Period

In DRX mode, in the first block of the Schedule Message, the MS receivesinformation about

. How many CB messages there are

. In which slot they will be transmitted

. Message identifiers (if there are fewer than 6 new messages)

If there are:

. No new CB messages in successive schedule periods, the MS endsup reading only the first block in each Schedule Message.

. 1 to 5 new CB messages, the MS does not need to read other blocksin the Schedule Message, but it still needs to read the new CBmessages.

. More than 5 new CB messages, the MS has to read more than oneblock in the Schedule Message plus all the new CB messages.

SchCB1

CB2

CB31

Sch Sch

60 s

.... ....

CB1



7.14 BSS6083 Mobile Station (MS) speed detection

The purpose of this feature is to determine the speed of the MobileStations (MSs) in GSM networks so that the fast moving MSs can bedirected to macro cells and the slower moving MSs respectively to microcells whenever configured so by the BSC. Furthermore, BSC staticticsalso collects this information.

The benefit of this feature is that it decreases the number of handovers in amicro-cell network and thus increases network capacity.

The BTS estimates the MS's speed by using the Crossing-rate algorithm.The algorithm is based on a comparison between the signal levelsobtained from each burst and their averaged value over one SACCHmultiframe. The algorithm counts the rate at which the signal level crossesthe averaged signal level. The crossing rate is relative to the MS's speed.The BTS sends the measured MS-speed information to the BSC byincluding it in the 'Meas_res' message. The MS-speed indication can varybetween 0 and 254 km/h (0 – 159 mph) in 2-km (1.25-mile) steps. Ifmeasurement averaging is used, MS-speed measurement results are alsoaveraged (see the figure below).

Figure 17. MS speed detection used for handover decision

BSCBTS

BTS

Macro cell

Micro cell(s)

Fast MSs

Slow MSs

Meas_res

Crossing-rate algorithm

HOs



Basic GSM operation

The handover-decision algorithm in the BSC takes into account the MS-speed results sent by the BTS. Furthermore, the MS-speed basedhandover parameters (nx, px, upper speed limit (USL) together with lowerspeed limit (LSL)) and the adjacent cell layer definitions are also used withthis feature.

The handover (HO) and power control (PC) algorithm determines the needfor the handover as follows:

. If px averaged MS-speed indications out of last nx averaged MS-speed indications exceed the USL, the MS is considered as a fastmoving MS and the call will be handed over to a suitable upper-layercell (macro cell) if any.

. If px averaged MS-speed indications out of last nx averaged MS-speed indications are lower than the LSL, the MS is considered as aslow moving MS and the call will be handed over to a suitable lower-layer cell (micro cell) if any.

Layer information and the umbrella handover criteria are used as thetarget cell selection criteria. This means that the RX level in the target cellhas to exceed the umbrella handover requirementHO_UMBRELLA_LEVEL defined for every adjacent cell.

Note

The algorithm does not work with frequency hopping.

7.15 BSS11052 Dynamic Frequency and ChannelAllocation (DFCA)

Dynamic Frequency and Channel Allocation (DFCA) is a radio channelallocation software for dynamically assigning the optimum radio channelfor a new connection.

DFCA uses interference estimations derived from mobile station downlink(DL) measurement reports and combines them with the timeslot andfrequency usage information. DFCA channel allocation algorithm selectsthe radio channel for a connection from a dedicated channel pool based oncarrier/interference (C/I) ratio criteria. The idea in DFCA channel selectionis to provide enough quality in terms of C/I, so that each connection willmeet its Quality of Service (QoS) requirements. The different degrees ofinterference tolerance of different connection types are taken into account



in the channel selection process. Examples of the connection types areconnections using enhanced full rate speech codec (EFR) or full rate (FR)and half rate (HR) connections using adaptive multi-rate speech codec(AMR).

The main DFCA functionality is located in the BSC. The DFCA channelallocation algorithm in the BSC controls the radio channel assignments ofall DFCA TRXs in all BTSs controlled by the BSC. The BTSs using DFCAmust be synchronised to a global clock reference provided by the GPSsatellite system. This is achieved by having a Location Measurement Unit(LMU) installed in every BTS site. The LMU incorporates a GPS satellitereceiver and provides a common clock signal that is used by all BTSs inthe site.

DFCA is used for circuit switched traffic. Packet switched traffic is nothandled by this software. The (E)GPRS territory is placed on a regularTRX which has been assigned to a separate portion of the frequency bandand controlled by the conventional channel allocation algorithm. DFCA is alicence-based application software. Its use is controlled by a capacitylicence based on the number of TRXs. To activate DFCA, the state of thelicence must be set to ON.

DFCA frequency hopping is a new frequency hopping mode supported byFlexi EDGE base stations with wide band combining from EP1.1 softwarerelease onwards. DFCA hopping is based on the basic principle ofsynthesised frequency hopping where the TRX unit changes the usedfrequency according to the given hopping sequence. With DFCA hopping,the TRX supports independent cyclic hopping sequences for each timeslotthat can be freely selected with each channel activation. With DFCAhopping, the BSC can freely select the MA-list, MAIO and TSC for eachTCH activation allowing the DFCA algorithm to choose the most suitableradio channel for each new connection or handover based on C/I criteria.This full channel selection freedom allows DFCA to achieve the bestperformance with DFCA hopping mode. The DFCA hopping mode isapplied only in the TRXs dedicated to DFCA use (DFCA TRXs).

Requirements

. The Flexi EDGE base station requires wideband combining or nocombiners.

. DFCA is not supported with RTC combiners.

. DFCA requires BSS synchronisation, which means that one LMUunit must be installed in every BTS site.

. Within a BTS, the use of DFCA is controlled on a 'per TRX' basis.



Basic GSM operation

In a BTS using DFCA, there are both DFCA and regular TRXs. TheDFCA TRXs do not support any signalling channels and thereforethe BCCH TRX of a BTS and a TRX carrying SDCCH channels mustbe a regular TRX.

Also (E)GPRS is not supported in the DFCA TRXs. Depending onthe requirements for the (E)GPRS territory size, this may require theoperator to define another regular TRX, in addition to the BCCH TRXof a BTS for carrying (E)GPRS.

The usage of DFCA frequencies for regular TRXs may cause somelocal DFCA performance degradation because of the uncontrolledinterference.


The following features cannot be used in a BTS using DFCA:

. IUO/IFH: DFCA will replace these features

. Dynamic Hotspots

. ICE

. Antenna hopping

The following features cannot be used in a TRX using DFCA:

. Dynamic SDCCH (not usable for the DFCA TRXs)

. FACCH call set up (not usable for the DFCA TRXs)

. Interference Band Recommendation: DFCA will replace thisfunctionality

. Power optimisation in handover: DFCA will replace this functionality

. (E)GPRS: PS territory is not allowed in DFCATRX but only in regularTRXs in DFCA



Benefits

. Enhanced quality: DFCA is able to handle different circuit switchedtraffic classes (EFR, HR, AMR, 14.4 kbit/s data) individually, and itprovides the operator with means to differentiate between users.This is especially powerful when the full benefit of AMR connectionsis wanted without 100% AMR penetration.

By guaranteeing a sufficient C/I level for each user, the networkperformance in terms of received signal quality (RXQUAL), frameerror rate (FER) and dropped call rate can be significantly improved.

. Capacity booster: The criteria of sufficient C/I for each connectionoptimises also the interference caused to other connections. Thisleads to significant capacity gain, as the use of the valuablefrequency resources is dynamically optimised.

By decreasing the effective frequency reuse distance in the network,DFCA enables the operator to accommodate more circuit switchedtraffic by adding more TRXs to the existing BTSs without qualitydeterioration. Alternatively, more frequencies can be used on theregular layer, thus increasing the performance and capacityavailable for (E)GPRS.



Basic GSM operation



8 Transmission

8.1 Basic transmission

8.1.1 Abis Trunk Transmission for E1 (ETSI) interface

Up to four full rate (FR) or Enhanced Full Rate (EFR) speech channels, orup to eight Half Rate (HR) speech channels, are multiplexed on a single 64kbit/s PCM timeslot. It is possible to create point-to-point star, multidropchain or remote star transmission connections between BSC and BTSsites. This flexibility ensures that all kinds of transmission needs arefulfilled: traditional star configuration, economical multidrop chains, andreliable multidrop loops are all possible.

Up to 12 TRXs are supported on a single 2 Mbit/s PCM line. See alsoBTS2503 Compressed Abis timeslot allocation.

Abis Trunk Transmission Allocation is implemented using the standardG.703 2 Mbit/s PCM frame structure.

For more information, see Nokia BSS Transmission Configuration in BSC/TCSM Product Documentation.


BSS30285 Activation of additional two E1/T1 interfaces



Transmission

8.1.2 Abis Trunk Transmission Allocation for T1 (ANSI) Interface

Up to four full rate/enhanced full rate (FR/EFR), and eight with Half Rate(HR) speech channels are multiplexed on a single 64 kbit/s PCM timeslot.It is possible to create point-to-point star, multidrop chain or remote startransmission connections between BSC and BTS sites. This flexibilityensures that all kinds of transmission needs are fulfilled: traditional starconfiguration, economical multidrop chains, and reliable multidrop loopsare all possible.

Up to 10 TRXs are supported on a single 1.5 Mbit/s PCM line. See alsoBTS2503 Compressed Abis timeslot allocation. This feature isimplemented using the standard T1.403 PCM frame structure.

The T1 TRAU supports Extended Super Frame (ESF) and SF/D4 framing.The ESF supports CRC-6 checks and 4 kbit/s data link for performancemanagement.


BSS30285 Activation of additional two E1/T1 interfaces

8.1.3 Abis Trunk Signalling

Radio Signalling Link is a logical link between the BSC and the BTS inLayer 2. The RSL is identified by a functional address known as ServiceAccess Point, SAPI=0. Radio signalling links over the Abis interface areaddressed to different units by Terminal Endpoint Identifiers, TEI. The TEIvalues are fixed and correspond to the TRX-id. The TEI management isnot used.

One signalling channel is used for each transceiver (TRX) and one foreach BTS base control function (BCF). Alternative signalling speeds areavailable: 16 kbit/s, 32 kbit/s, or 64 kbit/s. The selection of the signallingspeed is done in the commissioning phase on BTS basis. The sameselection is also done on the BSC site when channel configuration isdefined.

Normally, 16 kbit/s TRX signalling speed is recommended for the FRoperation. 32 kbit/s TRX signalling rate is recommended for the HR use.

At the BCF signalling rate of 64 kbit/s, the SW downloading time needed isapproximately four times shorter than with 16 kbit/s signalling.



8.1.4 Network Synchronisation

In normal network conditions, synchronisation information is carried byselected 2 Mbit paths from upper to lower hierarchical levels according tothe synchronisation plan, from the MSC down to the BTSs.

Nokia Flexi EDGE BTS selects the 2 Mbit signal that has the highestpriority from a group of pre-selected digital paths as the activesynchronisation signal. The operator can change the group of signalsusing the Nokia Flexi EDGE BTS Manager application. Selection of a newsignal is automatic in case of input failure and input recovery.

In addition to using 2 Mbit signals for synchronisation, it is possible tosynchronise with an external clock signal, such as the LMU clock signal.

Network Synchronisation can be protected via PDH Loop Protection. SeeBSS30280 Abis loop protection for more details.

8.1.5 Transmission equipment management

The management protocol for Nokia’s transmission equipment is Q1. Thetransmission equipment can be external or internal to the BTS. Theexternal equipment can be connected to the Nokia Flexi EDGE BaseStation using a Q1 cable or a configured Q1 embedded operationschannel (EOC).

Either the base station controller (BSC) or Nokia Flexi EDGE Base Stationcan supervise the transmission equipment. The Q1 protocol is a master/slave protocol. The master regularly polls the slaves. If the BSC is themaster, the transmission equipment is said to be under 'BSC polling'. If theFlexi EDGE BTS is the master, the transmission equipment is said to beunder 'BTS polling'.

The alarms that the transmission equipment generates are transmitted tothe BSC, which further transfers them to Nokia NetAct.

If the BTS is the master, the BTS reports the transmission alarms to theBSC via the OMUSIG channel.

If the BSC is the master, the BSC polls the alarms directly. A managementchannel must be configured throughout the radio network between theBSC and the transmission equipment. The management channelconfiguration at the BSC (service channel) must match the configuration atthe transmission equipment (embedded operations channel).



Transmission

All equipment on the same channel must have a unique address (pollingaddress) to avoid conflicts. Only one master polls all transmissionequipment. Loops are not allowed, because Q1 is a bus protocol.

With Nokia Flexi EDGE BTS, it is not necessary to manually configure anyQ1 switches to establish the internal Q1 paths. The configuration is doneautomatically based on the Q1 polling mode. As a consequence, allinternal or external transmission devices connected to the BTS must beeither BTS-polled or BSC-polled. A combination of polling modes is notpossible. This is important to keep in mind particularly when configuringthe external devices (which are connected to the BTS either via a Q1 cableor the EOC).

It is not possible to change the polling mode for the internal transmissionequipment manually at the Nokia Flexi EDGE BTS. It is the result of theconfiguration at the BSC. If the Q1 polling mode is 'BSC Polling', the Q1address value is read from the BSC (0-3999). The Q1 address can bemanually configured from the Flexi EDGE BTS Manager. This should,however, be avoided to prevent conflicts.

With the Q1 Interface Handling BSC MML commands, the user creates theservice channels used in communication between the BSC and thetransmission equipment. The Q1 service channels are asynchronousserial communications channels. The default maximum number of Q1service channels in the BSC is 18. The user must define every supervisedequipment at the BSC. Altogether 512 pieces of equipment can be definedinto Q1 service channels under the BSC.

Supervision of transmission units supplied by other manufacturers

When transmission units supplied by other manufacturers are supervisedvia External Alarm and Control (EAC) lines, the alarms can be sent to theBSC and NetAct. When the alarms are sent to the BSC and NetAct, theSystem Module (ESMA) supervises the alarm handling, and alarms arereported as normal external alarms.

8.1.6 Support for Nokia Microwave Radio Links

The FlexBus transmission sub-module (FIFA) forms the integratedmicrowave unit support with Nokia Flexi EDGE BTS.

One FIFA transmission sub-module is used per Nokia Flexi EDGE BTSwith two FlexBus interfaces, allowing for microwave radio tail and chainsite topologies using Nokia FlexiHopper and MetroHopper.



The FIFA sub-module offers E1 bypass cross-connections from oneFlexBus interface to the other, and up to 16xE1 add/drop capability toNokia Flexi EDGE BTS and sub 2M cross-connect function of which up to8xE1 can be dropped to the BTS itself.

The FIFA sub-module is visible as a separate managed element at NokiaNetAct. The operator can manage the FIFA sub-module locally andremotely using Nokia FlexiHub manager. Nokia Flexi EDGE BTS providesfunctions for alarm, performance data polling and forwarding to the BSC.

Some features related to Nokia Microwave Radio require an applicationSW licence, for example the L55341.05 licence for an additional FlexBusinterface.

8.1.7 BSS9065 Transmission Operability

Nokia Flexi transmission equipment is measured with several counters:

. All equipment can be measured within 15-minute/24-hour periods.This measurement gives a fixed set of counters, which are near-endG.826 signal quality counters. These counters are:. Total time. Available time. Errored seconds. Severely errored seconds. Background block errors. Errored block

. A certain set of Nokia Flexi transmission equipment can be defined.Nokia Flexi transmission equipment refers either to the wholeequipment or part of it (functional entity and supervision block). It isalso possible to define the counters that are collected from theequipment. To do this, the topology of the transmission network mustbe known so that the measurement subject can be chosen.



Transmission

8.2 Transmission solutions

8.2.1 PDH traffic routing

Cross-connections define how signals are routed from a transmissioninterface to another transmission interface. They are the basic buildingblocks for creating the path for transmitting the Abis capacity from theNokia BSC to the Nokia BTS via interconnecting nodes.

Cross-connection granularities

There are several types of cross-connections available, and each has adifferent granularity. Granularity means the bit rate at which a cross-connection is made, that is, the number of bits connected into a specificdirection in a cross-connection. In 2 Mbit/s mode, the availablegranularities are:

. 8k (1 bit)

. 16k (2 bits)

. 32k (4 bits)

. 64k (all 8 bits in a time slot)

. n x 64k (where n = 1 - 31)

BSS21129 Grooming

The cross-connection feature of the transmission units makes trafficgrooming possible.

Nokia Flexi EDGE BTS is capable of grooming traffic at for example 8 kbit/s granularity, which enables fully optimised and flexible use of the availabletransmission resources. This ensures that the path used for transmittingAbis capacity can be used efficiently.

8.2.2 BSS 30280 Abis loop protection

Nokia PDH loop protection is an efficient way to protect traffic in atransmission network such as a base station subsystem (BSS). In a livetelecommunications network it is important to secure, in addition to theactual payload traffic, the network synchronisation and the centralisednetwork management during any period of abnormal circumstances.

For these reasons, Nokia PDH loop protection protects:



. payload traffic

. network synchronisation

. network management connections

A transmission loop formed with Nokia elements consists of a loop masterand one or more loop slaves. Usually the loop master is a transmissionnode, whereas the loop slaves can be either transmission nodes, BTSs ora combination of both inside one loop.

The loop principle is that the transmitted signal is always sent in bothdirections, but the received signal is selected from one direction only. Theloop master sends pilot bits on the basis of which the switching decision ismade. Each individually protected slave station needs one pilot bit.

Network synchronisation must also be ensured in a loop network, and itfollows the loop principle in a similar way. The synchronisation switchingtakes place independently from the pilot bits by having master clock bit(MCB) and loop control bit (LCB).

Based on the configured priorities, each network element decidesindividually from which direction the signal and the synchronisation will bereceived, and, thus, it does not require any external or additionalsupervision for its decision.



Transmission

Figure 18. Loop principle

Nokia's way of implementing loop protection is ultimately secure, providingvery fast route switching that recovers the transmission connectionsinstantly. Nokia loop protection is embedded and thus very fast. The loopprotection protects against failures, such as cable-cuts, equipmentfailures, heavy rain and multipath fading, and against obstacles in the line-of-sight, such as cranes and growing trees.

Compared to an unprotected wireless network, Nokia PDH loop protectionincreases site availability at least tenfold and prevents end-of-chainavailability degradation.

The protection functionality is compatible with the existing Nokia BSStransmission.

Nokia Flexi EDGE BTS can only act as a slave node in a Nokia PDH Loopprotected network.

For more information refer to the Nokia PDH Loop Protection in GSMNetworks document that can be obtained upon request.

Loopmaster

= Loop slave

Normal receive direction

Reverse receive direction

Pilot bitsPilot bits

Direction 1Direction 2

Transmissionnetwork



8.2.3 Redundant Abis Trunk

If a failure or a problem in the transmission connection occurs between theBSC and the BTS sites, an alternative transmission route (redundancy) isdesirable.

Two alternative strategies are available for redundancy:

. a duplicated point-to-point type connection

. a redundant multi-drop loop connection

These two alternatives provide solutions for different transmission needs:either the traditional redundant point-to-point configuration or theeconomical multidrop loop configuration.

Redundant Abis Trunk for E1 interface (ETSI) is implemented by using thestandard G.703 2 Mbit/s PCM frame structure.

Redundant Abis Trunk for T1 interface (ANSI) is implemented by using thestandard T1.403 1.5 Mbit/s PCM frame structure.

For more information, see Nokia BSS Transmission Configuration in BSC/TCSM Product Documentation.

8.3 BSS10045 Dynamic Abis allocation

Dynamic Abis provides an efficient transport mechanism for GPRS andEGPRS to use more than one 16 kbps subchannel on the Abis interfacefor each packet data channel (PDCH) on the Air interface. The continuousareas of PCM timeslots on PCM links are configured as Dynamic Abispools (DAPs) to provide the needed capacity.

The dual TRX modules support two carriers, each of which belongs to onelogical TRX. Each logical TRX utilising Dynamic Abis is associated with aDAP in addition to the standard fixed traffic channel (TCH) area. Anypacket data channel would be continuously using a master PCU channellocated on a fixed area. Depending on the traffic load on each Air interfacechannel, more capacity would be allocated from the DAP. See the tablebelow for the number of 16 kbps DAP subchannels used with each CS andMCS.



Transmission

Table 4. Number of 16 kbps DAP subchannels used with each CS and MCS

CS/MCS Number of DAP subchannels

CS1 0

CS2 1

CS3 1

CS4 1

MCS-1 0

MCS-2 1

MCS-3 1

MCS-4 1

MCS-5 1

MCS-6 2

MCS-7 3

MCS-8 4

MCS-9 4

The PCU controls the downlink and uplink slave allocation on a radio blockbasis. Any 20 ms period on Abis is controlled based on real traffic demand.Downlink and uplink allocations are controlled separately. The slaveallocation is informed to the BTS by in-band signalling on thecorresponding downlink master channel.

Multiple logical TRXs can share a DAP. Multiple DAPs can be configuredfor each BTS and for each physical Abis link.

O&M signalling, TRX signalling, and circuit-switched channels are usedwith Dynamic Abis in the same way as they are used with the Nokiaconventional Abis solution.

8.4 BSS5850 Satellite Abis

Satellite Abis allows the use of satellite connections on the Abis interfacebetween the BSC and the BTS. Satellite Abis enables you to createnetwork coverage in areas where the coverage could not otherwise beimplemented because of the limitation of the transmission media. Typically,these remote BTSs are used in low-capacity and temporary applications.The BTS software adapts to the satellite delay (max 280 ms in onedirection) and the BSC and BTS perform the necessary alignments. Notethat satellite Abis restricts the BTS performance in higher capacity



activities on CS and PS data. It is recommended to configure the BTS sothat a non-combined BCCH configured and a SDCCH/8 to the TCHs onlyTRX, whenever possible. It is also recommended to configure PS data sothat high coding schemes are used only in one timeslot or that low codingschemes are used in multiple timeslots.

This feature is activated for each BSS individually. It is activated by anAbis_type parameter switch in both the BSC and the BTS.



Transmission



Appendix A Other features

A.1 Other features

Nokia Flexi EDGE BTS also supports the following feature enhancementsmade in Nokia UltraSite EDGE BTS:

. Enhanced Automatic Frequency Correction (E-AFC)

. BSS10022 Frame Erasure Rate (FER) Measurement

. BSS9064 Real Time Update to BTS

. BSS7048 CCCH Improvements

. BSS6074 Active Channel Interference Estimation

. BSS5072 Better Random Access Channel Detection

. BTS2041 BTS Local Blocking



Other features

Documents

Flexi EDGE BTS Feature Description