49529487 abis interface

This confidential document is the property of NORTEL MATRA CELLULAR and may not be copied or circulated without permissionCe document confidentiel est la propriété de NORTEL MATRA CELLULAR et ne peut être reproduit ou communiqué sans autorisation

Distribution lists :

Abstract / comments :

This is an internal document that applies up to the V12 BSS release.

This document is available at the following Netscape location:

http://136.147.68.68/ned/ERGmain.html

Abis Interface Engineering Guide

GSM

Reference : PE /IRC/APP/0079Version : 01.08 / ENDate : 12/04/99Author : T. BachelierDocumentalist : A.-M. LeberreApproved by : M. LiemQuality manager :Ext. ref. :Type : CEVProduct :Cat : IStatus : A



PE /IRC/APP/0079 01.08 / EN 12/04/99

DOCUMENT AMENDMENTS

VERSION DATE COMMENTS AUTHOR

01.01 / EN 03/06/98 Creation - Preliminary edition T. Bachelier

01.02 / EN 19/06/98 Update after review Preliminary editionSee report: PE/IRC/GES/0034 V1.01

T. Bachelier

01.03 / EN 15/07/98 New minutes have been taken into account T. Bachelier

01.04 / EN 31/07/98 Modification after review + rewritingSee report: PE/IRC/GES/0034 V1.02

T. Bachelier

01.05 / EN 16/12/98 US and China comments have been taken into ac-count

T. Bachelier

01.06 / EN 24/12/98 Modification after reviewSee report: PE/IRC/GES/0034 V1.03

T. Bachelier

01.07 / EN 25/03/98 The main changes are on LAPD dimensioning:Engineering rules have been completely remade,they are given for each type of BTS which allowsmore flexibility.

T. Bachelier

01.08 / EN 12/04/98 Modification after review. T. Bachelier


GSM

Reference : PE /IRC/APP/0079Version : 01.08 / ENDate : 12/04/99

ABIS INTERFACE ENGINEERING GUIDE



PE /IRC/APP/0079 01.08 / EN 12/04/99

TABLE OF CONTENTS

1 INTRODUCTION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8

1.1 PURPOSE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 81.2 SCOPE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8

2 RELATED DOCUMENTS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9

2.1 APPLICABLE DOCUMENTS. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 92.2 REFERENCE DOCUMENTS. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9

3 ABBREVIATIONS AND DEFINITIONS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11

3.1 ABBREVIATIONS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 113.2 DEFINITION OF TERMS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13

4 BTS CONFIGURATION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15

4.1 SITES AND CELL LAY-OUT . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 154.2 OFFERED TRAFFIC ASSESSMENT . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 154.3 RADIO INTERFACE DIMENSIONING . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15

4.3.1 TCH. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 154.3.2 SDCCH . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 164.3.3 BCCH . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16

4.4 CELL DIMENSIONING . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 174.4.1 Cell types . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 174.4.2 BTS configuration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17

4.5 LOOK-UP TABLES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18

5 BTS DIMENSIONING . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20

5.1 SIGNALLING . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 205.1.1 LAPD channel . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 205.1.2 LAPD dimensioning. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21

5.2 PCM . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 265.2.1 Abis TS dimensioning . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 265.2.2 PCM configuration rules . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26

5.3 DCC & DSC DIMENSIONING . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 295.4 LOOK-UP TABLES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30

6 ABIS ARCHITECTURE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33

6.1 DROP&INSERT CONFIGURATIONS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 336.1.1 Possible configurations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 336.1.2 TEI issues . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34



PE /IRC/APP/0079 01.08 / EN 12/04/99

TABLE OF CONTENTS

6.1.3 DTI/PCMI issues . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 356.1.4 RadioSiteMask configuration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 376.1.5 RadioSiteMask Extension strategy. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 406.1.6 Additinal feature of TDMA/Abis mapping configuration for V11 . . . . . . . 42

6.2 HUBS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 436.2.1 Cross-connect . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 436.2.2 Switch. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 44

7 TRANSMISSION MEDIUM . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 46

7.1 CLOCK . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 467.2 TRANSMISSION QUALITY REQUIREMENTS . . . . . . . . . . . . . . . . . . . . . . . . . 477.3 CSU. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 497.4 HDSL. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 49

7.4.1 Introduction. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 497.4.2 HDSL issues. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 507.4.3 HDSL modems . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 50

7.5 MICROWAVES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 517.5.1 Microwave design Guidelines. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 517.5.2 Microwave Quality requirements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 537.5.3 Microwave configurations. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 547.5.4 Microwave equipment redundancy. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 56

8 BSC DIMENSIONING . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 58

8.1 BSC TYPE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 588.2 SICD/SICD8V BOARDS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 59

8.2.1 Limitation rules . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 598.2.2 Parenting rules . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 598.2.3 Look-up tables . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 60

8.3 BSCB AND TSCB BOARDS. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 608.4 DDTI BOARDS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 62

9 APPENDIX . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 63



PE /IRC/APP/0079 01.08 / EN 12/04/99

LIST OF TABLES

Table 1: BTS configuration limitations .............................................................................. 17Table 2: Traffic for a given number of TRXs in a standard cell ........................................ 18Table 3: Traffic for a given number of TRXs in an extended cell...................................... 18Table 4: PCM configuration for S333 (TEI 0) with 1 PCM............................................... 26Table 5: PCM configuration for S333 (TEI 0) with 2 PCMs ............................................. 27Table 7: Internal E1 to external T1 conversion .................................................................. 28Table 8: LAPD/DCC configuration.................................................................................... 29Table 9: Omnisectorial BTS ............................................................................................... 30Table 10: Bisectorial BTS................................................................................................... 30Table 11: Tri and hexasectorial BTS .................................................................................. 31Table 13: PCM E1 RadioSiteMask..................................................................................... 38Table 14: PCM T1 RadioSiteMask..................................................................................... 38Table 15: PCM E1 RadioSiteMask..................................................................................... 39Table 16: PCM T1 RadioSiteMask..................................................................................... 39Table 17: RadioSiteMask (first strategy)............................................................................ 41Table 18: RadioSiteMask (second strategy) ....................................................................... 41Table 19: RadioSiteMask (Third strategy) ......................................................................... 42Table 20: RadioSiteMask configuration with crossconnect ............................................... 44Table 21: Timing requirements........................................................................................... 46Table 22: Product range...................................................................................................... 58Table 23: SICD limitations ................................................................................................. 60Table 24: Maximum number of sites per BSC ................................................................... 61Table 25: PCM allocation for the BSC6000 Type5............................................................ 62



PE /IRC/APP/0079 01.08 / EN 12/04/99

LIST OF FIGURES

Figure 1: Star, Drop&Insert and Hub&Spoke Configurations ........................................... 33Figure 2: Loop Drop&Insert configuration ....................................................................... 34Figure 3: Hub&Spoke configuration. ................................................................................. 34Figure 4: PCMI configurations for drop&insert ................................................................. 35Figure 5: D&I in loop without board redundancy: 1G versus 2G ...................................... 36Figure 6: Drop & Insert example ........................................................................................ 38Figure 7: Hub&Spoke example .......................................................................................... 39Figure 8: Example............................................................................................................... 40Figure 9: Cross-connect configuration ............................................................................... 43Figure 10: Crossconnect configuration............................................................................... 43Figure 11: Architectuire with Switch ................................................................................. 44Figure 12: HDSL solution................................................................................................... 49Figure 13: Microwave solution........................................................................................... 51Figure 14: Reference communication of ITU..................................................................... 53Figure 15: Performance objectives: .................................................................................... 53Figure 16: Chain Drop&Insert with microwaves ............................................................... 54Figure 17: Loop Drop&Insert with microwaves................................................................. 54Figure 18: Hub and Spoke with microwaves...................................................................... 55Figure 19: Abis configuration with microwaves on BSC side ........................................... 55Figure 20: Typical non-protected and protected microwave equipment architecture ........ 56Figure 21: Dimensioning the Abis interface with LAPD concentration ............................ 61Figure 22: Example of complex configuration ................................................................... 63


Abis Interface Engineering Guide /64

PE /IRC/APP/0079 01.08 / EN 12/04/99

1 INTRODUCTION1.1 PURPOSE

The purpose of this document is to give Abis interface engineering guidelines for theNORTEL BSS network.

This document is discusses the following subjects:

v Dimensioning speech and signalling on the Abis interface,

v Impact on the BTS side,

v Abis architecture,

v Transmission medium (HDSL, microwaves),

v Impact on the BSC side.

This document is intended primarily for Network Designers and ApplicationEngineers involved in GSM network Engineering within NORTEL GSM Networksand Nortel.

1.2 SCOPE

This document is internal and applies up to the V12 Release.



PE /IRC/APP/0079 01.08 / EN 12/04/99

2 RELATED DOCUMENTS

2.1 APPLICABLE DOCUMENTS

[A01] Feature list of System Release V11PE/SYS/DPL/0089 V01.02/EN P. Vincent

[A02] Dimensioning the Abis interfacePE/SYS/DD/0070 V6.02/EN B. Couaillet

[A03] Transmission Network RecommendationsPE/SYS/DD/0253 V1.03/EN B. Couaillet

2.2 REFERENCE DOCUMENTS

[R01] V8 Engineering ChangesPE/IRC/APP/00030 V1.06/EN L. Jullien

[R02] V9 Engineering ChangesPE/IRC/APP/00048 V1.06/EN T. Bachelier

[R03] V10 Feature Engineering InformationPE/IRC/APP/00068 V1.08/EN S. Luong

[R04] V11 Feature Engineering InformationPE/IRC/APP/00072 V1.06/EN T. Bachelier

[R05] S8000 Outdoor BTS Engineering InformationPE/IRC/APP/00033 V4.02/EN Y. Maurin

[R06] S8000 Indoor BTS Engineering InformationPE/IRC/APP/00055 V4.02/EN Y. Maurin

[R07] S2000H BTS Engineering InformationPE/IRC/APP/00052 V3.04/EN M. N. Boursin

[R08] S2000L BTS Engineering InformationPE/IRC/APP/00053 V3.04/EN M. N. Boursin

[R09] BSC/TCU Engineering InformationPE/IRC/APP/00015 V5.04/EN B. Vanheeghe

[R10] OMC-R Engineering Information (Vol. 1)PE/IRC/APP/00016 V5.04/EN M. Lebas

[R11] BSS Parameters User GuidePE/IRC/APP/00037 V3.01/EN WGAl-WGSys

[R12] Defence mechanisms on PCM faultsPE/SYS/DD/0242 V3.01/EN B. Couaillet



PE /IRC/APP/0079 01.08 / EN 12/04/99

[R13] UIT-T RecommendationsG732 Characteristics of primary PCM multiplex equipment operating at 2048 kbit/s.

[R14] UIT-T RecommendationsG811 Timing requirements at the output of primary reference clocks suitable for ple-siochronous operation of international digital links.

[R15] UIT-T RecommendationsG733 Characteristics of primary PCM multiplex equipment operating at 1544 kbit/s.

[R16] UIT-T RecommendationsThe control of jitter and wander within digital networks which are based on the2048 kb/s hierarchy.

[R17] UIT-T RecommendationsThe control of jitter and wander within digital networks which are based on the1544 kb/s hierarchy.

[R18] CT5100 Specification for Backhaul OptimizationPE/SPC/DD/00xx V1.01/EN A. Chevalier

[R19] GSM Transmission Engineering GuidePE/IRC/APP/0086 V1.01/EN B. Pariseau

[R20] Nortel BSS performancesPE/BSS/DJD/0456 V1.01/EN A. Montès

[R21] HDSL modem layer1 qualificationPE/BTS/DJD/0962 V10.01/EN B. Corn

[R22] BSCB Eng’g Information: Load Monitoring and OptimizationPE/IRC/INF/0015 V1.01/EN B. Vanhèeghe



PE /IRC/APP/0079 01.08 / EN 12/04/99

3 ABBREVIATIONS AND DEFINITIONS

3.1 ABBREVIATIONS

BCF Base Common FunctionBDA Application DatabaseBER Bit Error RateBPUG BSS Parameters User GuideBSC Base Station ControllerBSS Base Station SubSystemBTS Base Transceiver StationCCCH Common Control ChannelCS Coupling SystemCSU Channel Service UnitDCC Data Channel Concentrator (BTS 1G)DSC Data Signalling Concentrator (BTS 2G)DCU Dual Channel UnitDIU Digital Interface UnitDM Degraded MinutesDRX Driver + Receiver + Frame ProcessorDTI Digital Trunk InterfaceES Errored SecondsFEI Feature Engineering Information (document)GSM Global System for Mobile communicationsHDSL High bit rate Digital Subscriber LineHG High gradeHLR Home Location RegisterHO HandoverH/W HardwareLA Location AreaLAPD Link Access Protocol on D channelLG Local GradeLOS Line Of SightL1M Layer 1 MeasurementsMG Medium GradeMS Mobile StationNMC Nortel Matra CellularNMC Network Management CenterNSS Network Sub-SystemO&M Operation and MaintenanceOMC Operation and Maintenance CenterOMC-R Operation and Maintenance Center-RadioOMN Operation and Maintenance Network



PE /IRC/APP/0079 01.08 / EN 12/04/99

PA Power AmplifierPBGT Power BudgetPCH Paging ChannelPCM Pulse Code ModulationPCMI PCM InterfacePEI Product Engineering Information (document)QOS Quality of ServiceRFU Radio Frequency UnitRV Rendez VousSES Severely Errored SecondsSMS-CB Short Message Service - Cell BroadcastSPCMI Small PCM InterfaceTBC To Be CompletedTBD To Be DefinedTCH Traffic ChHannelTCU Transcoder UnitTEI Terminal Equipment IdentifierTMG Traffic ManagementTRX Transmission-Reception subsystem of the BTSTS Time Slot



PE /IRC/APP/0079 01.08 / EN 12/04/99

3.2 DEFINITION OF TERMS

C/I:

Carrier-to-Interference ratio, measured in dB, gives the measure of the ratio of theusable signal over the interferences level.

DRX:

The DRX is a part of the "2G" BTS system architecture. The first product thatsupports this architecture in the Nortel catalogue is the S8000 Outdoor BTS. In the"2G" architecture, the TRX is composed of two modules, one dedicated to the signalprocessing (transmission and reception) called DRX, and one dedicated to the powertransmission, called PA.

Rendez Vous time slot:

This is the time slot of the Abis interface PCM link that carries the primary LAPD ofthe BTS site. It has a fixed predefined position on the PCM (BTS side) because it isthe time slot used by BSC and the BTS to establish their first dialogue after ascanning procedure.

Soft Blocking:

Procedure by which a TRX or a cell can be put out of service (i.e. blocked) withoutinterrupting the given TRX or cell active calls.



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Page Intentionally Left Blank



PE /IRC/APP/0079 01.08 / EN 12/04/99

4 BTS CONFIGURATION

The site and the type of each BTS must be determined to perform the dimensioningof the Abis interface. This part is performed by the Cellular planning in conjunctionwith the network designer and the customer.

4.1 SITES AND CELL LAY-OUT

The sites and the cell layout are fixed according to the coverage prediction. Thereare two different ways of working depending on the project context.

vIf the customer defines the site locations, then Nortel must define the predictedcoverage area.

vIf the customer does not define the site locations, Nortel assumes additionalactivities for the site acquisition process follow-up such as along the siteacquisitions iterations, provision of optimal theoretical site location, site selectionrules, and coverage/quality impact of candidate site selection.

4.2 OFFERED TRAFFIC ASSESSMENT

The BTS configurations depend on the traffic (in Erlangs) that each cell must carry.Traffic is assessed with two kinds of information: quality of service and subscriberbehaviour. The behaviour of subscribers includes the distribution of GSMsubscribers within the population, call profile, and mobility parameters. The offeredtraffic of each cell is worked out from this information.

4.3 RADIO INTERFACE DIMENSIONING

The offered traffic is assessed. The next step is to dimension the radio interface.

4.3.1 TCH

The number of required TCHs is worked out from the Erlang B-law with a fixedblocking rate applied to the assessed offered traffic. The assumption of NORTEL isa blocking rate of 2% for traffic or data on the radio interface. One TCH channel iscarried by one radio TS.

Note that an ErlangB calculator is available at the following URL address:

http://47.53.64.96/syseng/2S00/2S30/ErlangBCalc/EBCalc.html



PE /IRC/APP/0079 01.08 / EN 12/04/99

4.3.2 SDCCH

The number of required SDCCH channels is difficult to assess because it dependson a large number of parameters:

• Mobility profile,

• Strategy used: For example, if most of the SDCCH requests are for call andnot for Location Update, it could make sense to use TCH signalling. It will al-low the decrease the call setup time. Therefore, no more SDCCH channelsare needed according to this strategy (Note that the Location Update will bealso supported by a TCH signalling). This strategy is only applicable to fewparticular cases, but it has a big impact on the dimensiong of the radio inter-face.

• geographical zone of the cell: If the cell is near an LA boundary, the numberof Location updates could be quite important. So, the number of SDCCHsmust be high.

• features used: Queueing increases the duration of the SDCCH connections,therefore the number of needed SDCCH may be studied.

This is not an exhaustive list. It just gives information about some parameters whichcan strongly impact the SDCCH dimensioning.

Nevertheless, if we take only into account the NORTEL standard traffic model, thenumber of required SDCCH can be easily determined.

The NORTEL standard traffic model indicates that 28 Erlangs of signalling traffic isrequired for 100 Erlangs of speech or data traffic. After determination of the signallingtraffic, the number of SDCCH channels is worked out from the Erlang B law.NORTEL assumption is a blocking rate of 0,1% for signalling on the radio interface.A radio TS can carry 8 SDCCH channels and is called SDCCH/8, but the SDCCHchannels can be combined with the BCCH (refer to the following paragraph).

4.3.3 BCCH

One BCCH is required per cell. The BCCH is supported by the TS0 of the beaconfrequency.

In the case of one TRX per cell, BCCH can combined with one SDCCH/4 (4 SDCCHchannels) in order to have 7 TCH instead of 6. This configuration can be appliedunder certain conditions such as the LA size. Actually, if the size of the LA is toolarge, a great amount of paging will be generated and the PCH (which is limited inthis configuration) will not be able to flow all the paging messages.

If the SMS-CB is implemented with combined BCCH, there will be only 3 SDCCHchannels.



PE /IRC/APP/0079 01.08 / EN 12/04/99

4.4 CELL DIMENSIONING

4.4.1 CELL TYPES

The number of required TRXs depends on the type of cells. There are two differentkinds of cell: standard and extended cell. Extended cell allows bigger propagationdelay. The coverage of an extended cell could be bigger than the one of a standardcell (for further information, please refer to [R02]).

TRX manages 8 TS in a standard cell and only four in an extended cell.

standard cell extended cell

unused TS

Standard cell is the default value used.

4.4.2 BTS CONFIGURATION

The number of required TRXs per cell is fixed according to two types of information:the number of required radio time slots and the cell type.

The BTS is determined by the cells that it must manage. For example a BTS whichmanages 3 cells with respectively 4, 5 and 2 TRXS is called a S452.

The dimensioning constants of the site are checked at the OMC level:

These limitations are only OMC-R checks. It does not necessary mean that the O16configuration exists.

TS0 TS1 TS2 TS3 TS4 TS5 TS6 TS7 TS0 TS1 TS2 TS3 TS4 TS5 TS6 TS7

Table 1: BTS configuration limitations

Cells per site 6

TDMA per cell 16

TRX per site 24



PE /IRC/APP/0079 01.08 / EN 12/04/99

4.5 LOOK-UP TABLES

The following look-up tables give the offered traffic for a given number of TRXs withthe NORTEL standard call profile (blocking rate of 2%). When the offered traffic isassessed, these look-up tables give a first assessment about the number of neededTRX. After this first assessment, some deeper dimensioning can be performedaccording to information of section 4.3.2 (SDCCH dimensioning).

Blocking rate = 2.0%

* Combined BCCH (under certain conditions such as LA size)

Table 2: Traffic for a given number of TRXs in a standard cell

TRX Erlangs E/TRX TCH SDCCH/8 BCCH

1 2.9 2.9 7 0 1*2 8.2 4.1 14 1 13 14.0 4.7 21 2 14 21.0 5.3 29 2 15 27.3 5.4 36 3 16 34.7 5.8 44 3 17 42.1 6.0 52 3 18 48.7 6.1 59 4 1

Table 3: Traffic for a given number of TRXs in an extended cell

TRX Erlangs E/TRX TCH SDCCH/8 BCCH

1 0.6 0.60 3 0 1*2 2.3 1.14 6 1 13 5.1 1.70 10 1 14 8.2 2.05 14 1 15 11.5 2.30 18 1 16 14.0 2.33 21 2 17 17.5 2.50 25 2 18 21.0 2.625 29 2 1



PE /IRC/APP/0079 01.08 / EN 12/04/99




PE /IRC/APP/0079 01.08 / EN 12/04/99

5 BTS DIMENSIONING

5.1 SIGNALLING

Two types of signalling are carried on the Abis interface. The first one, related to theOperation and Maintenance, concerns all the component parts (BCF, TRX, Couplingsystem, Power Amplifier ...). The second one, related to the traffic management, isdestined to the TRX module. In other words, all the modules receive O&M signalling,while the TRX receives both O&M and traffic management signallings.

5.1.1 LAPD CHANNEL

These two types of signalling (O&M and radio management) are supported by thesame LAPD channel. A distinction is made between the BCF signalling and the cellsignalling.

Primary LAPD: The primary LAPD is the LAPD channel which handles BCF signalling with cell signalling.

Secondary LAPD: It is the LAPD channel associated to a cell. It comprises only cell signalling.



PE /IRC/APP/0079 01.08 / EN 12/04/99

5.1.2 LAPD DIMENSIONING

LAPD dimensioning depends on BTS limitations, Abis transmission costs and BSClimitations. At BTS side, the hardware and software limitations are related to the BTStype. At BSC side, two main limitations can occur: connectivity (maximum number ofLAPD ports) and real time processing capability.

In fact two different strategies can be chosen by the operator to drive the LAPDdimensioning:

• The first one consists in concentrating the maximum number of LAPD chan-nels at the BTS side in order to save some TS on the Abis interface. The pur-pose is to decrease the transmission costs and to save some LAPD ports at theBSC side. The drawback of this strategy is that it can create some BSC over-load and lead to outage in worst case. Therefore, this strategy must be associ-ated with a capacity analysis to ensure that the BSC can manage suchconfiguration.

• The second one is highly related to the BSC load. As the BSC real time pro-cessing is a key factor in BSS design, it is of interest to split the signalling loadon the different boards in order to avoid an overloab on one board.

Of course, these two opposite strategies must fulfilled the BTS constraints. Eachtype of BTS has its own limitations due to hardware or software characteristics.

This part deals with the BTS limitations and the BSC limitations in terms of real timeprocessing. The BSC connectivity and the parenting rules at the BSC side will beseen in section 8 (BSC dimensioning).

BTS Limitations

The limitations depends on the BTS type. Each kind of BTS has its own limitations,therefore the engineering rules are different depending on the BTS type.

The low capacity BTS such as S2000H/L or S2000P are not taken into accountbecause they always need one single LAPD channel. In fact, four different BTS havebeen taken into account:

• S4000,

• S8000 BCF up to V11 (O&M software),

• S8000 BCF since V12 (COAM software),

• S8000 CBCF .



PE /IRC/APP/0079 01.08 / EN 12/04/99

S4000:

The maximum configuration is S888.

The engineering rules are:

v Omnidirectional BTSs (up to O8) require only one LAPD channel.

v Multi-sectorial sites having more than 8 TRXs require one LAPD channel per cell.

v The signalling of multi-sectorial sites having up to 8 TRXs can be handled by asingle LAPD channel. But, for the sake of the BSC boards (refer to the followingsection: BSC limitations in terms of real time processing), one LAPD per cell canbe defined.

S8000 BCF up to V11:

The maximum configuration is S888 and S444_444, S555_333, S666_222 fordualband site.


v Omnidirectional BTSs (up to O8) require only one LAPD channel.

v Multi-sectorial sites having more than 8 TRXs require one LAPD channel per cell.

v The signalling of multi-sectorial sites having up to 8 TRXs can be handled by asingle LAPD channel. But, for the sake of the BSC boards (refer to the followingsection: BSC limitations in terms of real time processing), one LAPD per cell canbe defined.

v For dualband configurations (hexasectorial applications) Sxyz_x’y’z’, the rulesare the following ones:

• if x+y+z+x'+y'+z' ≤ 8, 1 LAPD can be sufficient.

• if x+y+z ≤ 8 and x'+y'+z' ≤ 8 then allocate 1 LAPD for each frequency band.

• if x+y+z > 8 or x’+y’+z’ > 8 then use 1 LAPD for x,x’, another LAPD for y,y’,and a third LAPD for z,z’

F If a site has several LAPD channels, they must be connected on different SICDports unless the system will not be configured correctly.




PE /IRC/APP/0079 01.08 / EN 12/04/99

S8000 BCF since V12:

The maximum configurations are O16 for omnisectorial site , S888 for multisectorialsite and S444_444, S555_333, S666_222 for dualband site.


v The number of DRX which can be handled by one LAPD channel is limited to 8.

v A site has a maximum of 3 Abis LAPD channels.

v If a cell has less than 8 TRX, it has only one LAPD channel.

v For dualband configurations (hexasectorial applications) Sxyz_x’y’z’, the rulesare the following ones:

• if x+y+z+x'+y'+z' ≤ 8, 1 LAPD can be sufficient.

• if x+y+z ≤ 8 and x'+y'+z' ≤ 8 then allocate 1 LAPD for each frequency band.

• if x+y+z > 8 or x’+y’+z’ > 8 then use 1 LAPD for x,x’, another LAPD for y,y’,and a third LAPD for z,z’

Examples:

S111 can have one, two or three LAPD channels.

O8 has necessarily 1 LAPD channel.

S444 can have 2 or 3 LAPD channels.





PE /IRC/APP/0079 01.08 / EN 12/04/99

S8000 CBCF

The maximum configurations are O16 for omnisectorial site , S161616 formultisectorial site and S444_444, S555_333, S666_222 for dualband site.

There are only two engineering rules:

v The number of DRX which can be handled by one LAPD channel is limited to 8.

v A site has a maximum of 3 Abis LAPD channels.

Examples:

S111 can have one, two or three LAPD channels.

O8 can have one, two or three LAPD channel.

S444 can have 2 or 3 LAPD channels. In case of 2 LAPD channels, 6TRxs can defined on each LAPD channels in order to split the load.





PE /IRC/APP/0079 01.08 / EN 12/04/99

BSC limitations in term of real time processing

The SICD board is the LAPD interface controller that manages the signallinginterface between the BSC, the TCU, and the BTS. The SICD4 board (not theSICD8V) can be the bottleneck of the BSC. Several BSC outages in the past weredue to an overload on the SICD4 card. The overload was either generated by highHandovers, Paging and Location Update rates or by particulary high voice trafficdemands on certain sites (e.g. heavy load sites).

An overload mechanism has been introduced on the SICD board. But if this overloadmechanism is triggered, it will penalize the traffic (Q.O.S.) on all sites associated withthe SICD.

Therefore, it is really important to split the load on the different SICDs in order toavoid overload on one SICD.

A site with less than 8 TRXs can easily be handled by a single LAPD channel.However associating one LAPD channel to one cell allows a finer balancing of theload on the available SICD boards. This implies that additional DCC/DSC cards maybe required on the BTS and that additional timeslots on the Abis interface are alsonecessary. Please refer to the concerned BTS Product Engineering Information.

But it could make sense not applying these engineering rules if the forecast site trafficis low, typically in rural area.

Note 1:These engineering rules are applicable in a normal non-congested cell. Theycannot be applied in a congestion situation (radio blocking rate > 5%).

Note 2:For the other rules (BSCB, SICD) which apply on the BSC side, please referto section 8 (BSC dimensioning).

F One LAPD channel must be associated to one cell in high traffic zone (urbanzone) for the sake of the SICD for the BSC 6000.



PE /IRC/APP/0079 01.08 / EN 12/04/99

5.2 PCM

5.2.1 ABIS TS DIMENSIONING

On the Abis interface, two consecutive TS are used per TDMA and one TS perLAPD.

example:S333 on 1 PCM: (3 + 3 + 3) * 2 = 18 Abis TS are required for traffic,

3 LAPD : 3 Abis TS are required for signalling,the total number of Abis TS is 21.

If there are several PCMs, the number of required TS will be higher (for furtherinformation, please refer to section 6.1.4).

S333 on 2 PCMs: 18 TS for traffic => 10 on the PCM1 and 8 on the PCM2, but the radioSiteMask reserves 10 TS on each PCM.3 TS for LAPD on each PCM.The total number of TS is (10 + 3)*2 = 26 Abis TS

5.2.2 PCM CONFIGURATION RULES

The configuration rules of this section apply to the BTS side.

E1 configuration rules

The TS0 of a E1 PCM is used for synchronization. The other TS will be configuredaccording to several rules.

vThe TS number carrying the primary LAPD, called Rendez-Vous TS (RV TS),obeys the following rule:

TS number = TEIBCF + 1. (with TEIBCF<16)

vThe TS associated to TRX are mapped by two on two consecutive TS. Theconvention is to use the higher TS of a PCM first, and then continue toward thelower.

vThe secondary LAPD channels will be mapped on the free TS following the TrafficTS.

vWhen several PCM link the BTS to the BSC, the traffic TS are equally shared onthose PCM.

SP : Signalling Link TS (Primary LAPD) T : Traffic TSSS : Signalling Link TS (Secondary LAPD)

Table 4: PCM configuration for S333 (TEI 0) with 1 PCM

TS # 31 30 29 28 27 26 25 24 23 22 21 20 19 18 17 16 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0

S333 T T T T T T T T T T T T T T T T T T SS SS SP



PE /IRC/APP/0079 01.08 / EN 12/04/99

Table 5: PCM configuration for S333 (TEI 0) with 2 PCMs

SP : Signalling Link TS (Primary LAPD)SS : Signalling Link TS (Secondary LAPD)T : Traffic TS

T1 configuration rules

Rules:

For T1 configuration, the TS will be configured according to several rules:

vThe TS number carrying the primary LAPD, called Rendez-Vous TS (RV TS),obeys the following rule:

TS number = TEIBCF + 1. (with TEIBCF<16)

But all the TEIs cannot be used for T1. TEIs number 3, 7, 11 and 15 are forbiddenfor T1. The association between the Abis TS on the BTS side and the possible TEInumber is provided by the following table.

For further information, please refer to the following explanations (next page).

vThe TS associated to TRX are mapped by two on two consecutive TS. Theconvention is to use the higher TS of a PCM first, and then continue toward thelower.

vThe secondary LAPD channels will be mapped on the free TS following the TrafficTS.


TS # 31 30 29 28 27 26 25 24 23 22 21 20 19 18 17 16 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0

S333 T T T T T T T T T T SS SS SP

T T T T T T T T

Table 6: TEI to TS association

TEI 0 1 2 4 5 6 8 9 10 12 13 14

TS 1 2 3 4 5 6 7 8 9 10 11 12



PE /IRC/APP/0079 01.08 / EN 12/04/99

Explanations:

For T1 PCM, the SPCMI/PCMI/DTI converts internal PCMs (still in E1: 32 TS) toexternal PCMs (T1: 24 TS). See Table 7.

Table 7: Internal E1 to external T1 conversion

This means that there is no corresponding external TS for the internal TS4.Information on the internal TS4 never leaves the BTS.

For the T1 PCM, the rule for RV TS calculation is still RV TS = TEI number + 1 butapplies to internal PCM. So, if the TEI was configured to value 3, the used TS wouldbe 4 and the BTS would still remain impossible to reach.

Therefore, TEIs number 3, 7, 11, 15 cannot be used for T1. The association betweenthe Abis TS on the BTS side and the possible TEI number is provided in the table 6.

E1 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31

T1 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24



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5.3 DCC & DSC DIMENSIONING

This part is not apllicable to S8000 CBCF, S2000H/L and S2000P. It is only relevantfor S4000 and S8000 BCF.

DCC/DSC concentrates LAPD signalling links onto a single one from the DRX andthe BCF to the BSC. It performs the inverse processing in the opposite way.

The rule used for dimensioning the DCC/DSC is:

vOne DCC/DSC per LAPD (redundancy not taken into account).

The following table summarises the number of used DCC/DSC depending on thenumber of cells and depending on the number of signalling concentrated links.

Note1: Certain configurations listed in the above table can only be achieved withdualband configurations.

Note2: If, at a given time, the number of available DCC/DSC runs under the thresholdgiven in the table above, the whole site may be definitively lost (until the right numberof DCC/DSC becomes available again). Therefore, it is strongly recommended tohave a spare DCC/DSC (the "+ 1" in the table represents the redundancy board).

Table 8: LAPD/DCC configuration

LAPD link F 1 2 3

CELL H

1 1 + 1

2 1 + 1 2 + 1

3 1 + 1 2 + 1 3 + 1

4 2 + 1 3 + 1

5 2 + 1 3 + 1

6 2 + 1 3 + 1



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5.4 LOOK-UP TABLES

These tables take only into account the hardware limitation for the LAPDdimensioning (one LAPD is enough if the total number of TRX is less than 8),because the engineering rules depend on too many parameters (rural or urbanenvironment, SICD or SICD8V board, high mobility).

These tables could be useful for a first high level assessment, but not for an accuratedesign of the network.

Moreover, some specific cases occur. For example, the S22 configuration can beperformed with the S2000H BTS. In this case the real configuration is 2 O2 BTS (notsynchronnized) colocated on the same site and linked in a Drop and Insertconfiguration. Two LAPD channels are required to handle the 2 BCF signalling and8 TS to handle the traffic of the four TDMA. Therefore, the number of required TS is10 and not 9.

PCM E1 (31 TS) / PCM T1 (24 TS)Blocking factor = 2.0%

Table 9: Omnisectorial BTS

Config Standard cell Extended cell E1 PCM T1 PCMErlang TCH Erlang TCH Traffic TS LAPD required TS E1 required TS T1 DCC

O1 2.9 7 0.6 3 2 1 3 1 3 1 1+1O2 8.2 14 2.3 6 4 1 5 1 5 1 1+1O3 14.0 21 5.1 10 6 1 7 1 7 1 1+1O4 21.0 29 8.2 14 8 1 9 1 9 1 1+1O5 27.3 36 11.5 18 10 1 11 1 11 1 1+1O6 34.7 44 14.0 21 12 1 13 1 13 1 1+1O7 42.1 52 17.5 25 14 1 15 1 15 1 1+1O8 48.7 59 21.0 29 16 1 17 1 17 1 1+1

Table 10: Bisectorial BTS


S11 5.8 14 1.2 6 4 1 5 1 5 1 1+1S22 16.4 28 4.56 12 8 1 9 1 9 1 1+1S33 28 42 10.16 20 12 1 13 1 13 1 1+1S44 42 58 16.4 28 16 1 17 1 17 1 1+1S55 54.6 72 23 36 20 2 22 1 22 1 2+1S66 69.4 88 28 42 24 2 26 1 14*2 2 2+1S77 84.2 104 35 50 28 2 30 1 16*2 2 2+1S88 97.4 118 42 58 32 2 18*2 2 18*2 2 2+1



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Table 11: Tri and hexasectorial BTS


S111 8.79 21 1.8 9 6 1 7 1 7 1 1+1S222 24.6 42 6.8 18 12 1 13 1 13 1 1+1S333 42.0 63 15.2 30 18 3 21 1 21 1 3+1S444 63.0 87 24.6 42 24 3 27 1 15*2 2 3+1S555 81.9 108 34,5 54 30 3 19*2 2 19*2 2 3+1S666 104.1 132 42.0 63 36 3 21*2 2 21*2 2 3+1S777 126.3 156 52,5 75 42 3 25*2 2 17*3 3 3+1S888 146.1 177 63.0 87 48 3 27*2 2 19*3 3 3+1

S111111 17.58 42 3.6 18 12 1 13 1 13 1 1+1S222222 49.2 84 13.7 36 24 6 18*2 2 18*2 2 3+1S333333 84.0 126 30.5 60 36 6 24*2 2 24*2 2 3+1S444444 126.0 174 49.2 84 48 6 30*2 2 22*3 3 3+1



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PE /IRC/APP/0079 01.08 / EN 12/04/99

6 ABIS ARCHITECTURE

6.1 DROP&INSERT CONFIGURATIONS

6.1.1 POSSIBLE CONFIGURATIONS

Different configurations are possible on the Abis interface. They are called Star,Drop&Insert, and Hub&Spoke configurations. The following figure presents thesedifferent configurations.

Figure 1: Star, Drop&Insert and Hub&Spoke Configurations

The loop and chain Drop&Insert configurations are guaranteed for up to 6 BTSs. Thetheorical limitation is 10 O1 BTSs on 1 E1 and 8 O1 BTSs on 1 T1, but R&D testsand guarantees up to 6 BTSs.

Star

BSC

BTS

Loop D&I

BSC

BTS

BTS

BTS

Chain D&I

BSC

BTS

BTS

BTS

BTS

BTS

PCMRedundant PCM.In case of loop, one side is considered as redundant PCM

Hub&Spoke

BSC

BTS

BTS BTS

BTS



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6.1.2 TEI ISSUES

When a BTS is in a chained configuration, the BCH TEI numbers assigned to eachBTS must be in an ascending sequence. The rule for the chain configuration isx<y<z. The values do not need to be adjacent.

Figure 2: Loop Drop&Insert configuration

For the Hub&Spoke configuration the requirements are x<y<z and x<w. There is noconstraint between w and the couple y,z (w and y can be equal). Note that theHub&Spoke is not considered as a D&I configuration because of the fork.

Figure 3: Hub&Spoke configuration.

Note that all the TEI can not be higher than 15.



PE /IRC/APP/0079 01.08 / EN 12/04/99

6.1.3 DTI/PCMI ISSUES

PCM interfacing is provided by the DTI board for 1G BTS (S4000, S2000, S2000E),and by the PCMI board for 2G BTS (S8000I/O, S2000H/L). DTI board handles theinterface of 1 PCM digital trunks. PCMI board handles the interface of 2 PCM digitaltrunks. The following table presents the mapping between PCM ports and PCMI/DTIboards.

The PCM links connecting the BSC to BTS must be arranged for synchronizationreasons. A PCM crossing a BTS enters via an even PCM port and leaves via an oddPCM port. For the loop configuration, the opposite path can be set up.

The following figure shows some different Drop&Insert configurations with or withoutPCMI board redundancy.

Figure 4: PCMI configurations for drop&insert

Table 12: PCM port

PCM ports PCMI board DTI board

0 PCMI 0 port 0 DTI 0






BSC

0

1

BTS

PCMI00

1

BTS

PCMI00

1

BTS

PCMI0

D&I in chain without redundancy D&I in loop without board redundancy

BSC

0

1

BTS

PCMI00

1

BTS

PCMI00

1

BTS

PCMI0

BSC

0

1

BTS

PCMI00

1

PCMI1

0

1

BTS

PCMI00

1

PCMI1

0

1

BTS

PCMI00

1

PCMI1

D&I in chain with board redundancy D&I in loop with board redundancy

BSC

0

1

BTS

PCMI0 0

1

PCMI1

0

1

BTS

PCMI0 0

1

PCMI1

0

1

BTS

PCMI0 0

1

PCMI1



PE /IRC/APP/0079 01.08 / EN 12/04/99

For 1G BTS in loop Drop&Insert without DTI redundancy (following figure), if a DTIfailure occurs, only one PCM will be lost and the opposite path will be activated. For2G BTS in the same configuration, if a PCMI failure occurs, two PCMs will be lost.Therefore as the two ways of connection will be impossible, the site will be lost. ThePCMI redundancy avoid to lost the site in case of PCMI failure.

Figure 5: D&I in loop without board redundancy: 1G versus 2G

Therefore, changing a S4000 by a S8000 is not as easy as it appears. There aresome impacts on redundancy, and then on reliability.

D&I in loop without board redundancy

BSC

0

1

BTS A

PCMI00

1

BTS B

PCMI00

1

BTS C

PCMI0

BSC BTS D

DTI0

BTS E BTS F

DTI1

DTI0 DTI0

DTI1 DTI1



PE /IRC/APP/0079 01.08 / EN 12/04/99

6.1.4 RADIOSITEMASK CONFIGURATION

Rules

For each site, a parameter called RadioSiteMask is configured in order to definewhich TS are reserved.

vThe same mask is applied to all the PCM connecting a BTS

vThe primary LAPD is not included in the mask.

The TS carrying the primary LAPD has a defined position on the BTS side: TS number = TEIBCF + 1.

vThe traffic TS are mapped by two on two consecutive TS. A convention is to usefirst the higher TS of a PCM and then continue toward the lower one. Thesecondary LAPD follows the same rules as the traffic TS.


Some engineering rules define the value of the RadioSiteMask (total number oftimeslots set to 1):

For 1 PCM connected: (Nb LAPD - 1) + Nb TRX *2For 2 PCM connected: (Nb LAPD - 1) + Ent[(Nb TRX + 1)/2] * 2For 3 PCM connected: (Nb LAPD - 1) + Ent[(Nb TRX + 2)/3] * 2For n PCM connected: (Nb LAPD - 1) + Ent[(Nb TRX + (n-1))/n] * 2

MIf the TEI are not adjacent, it is strongly recommended not to use the TS betweenTS0 and the TS which carried the primary LAPD of the BTS with the bigger TEI.



PE /IRC/APP/0079 01.08 / EN 12/04/99

Example 1

This first example concerns a chain configuration. One S444 and one S222 arelinked together in order to optimize the transmission link.

Figure 6: Drop & Insert example

In this example the PCM4 is a redundant PCM. Note that the TEI are in ascendingsequence.

The traffic of the BTS A is equally shared between the 2 PCMs. The secondaryLAPD follow the TS supporting the traffic. The primary LAPD is not included in theradioSiteMask.

The BSC is a BSC6000, then 3 LAPD channels are defined for the site B in order tobe able to split the load on the different SICDs.

Ta Traffic Ts site A Pa Primary LAPD site ATb Traffic Ts site B Pb Primary LAPD site BSa Secondary LAPD site ASb Secondary LAPD site B

Table 13: PCM E1 RadioSiteMask

TS number 31 30 29 28 27 26 25 24 23 22 21 20 19 18 17 16 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0

PCM 1 Ta Ta Ta Ta Ta Ta Ta Ta Ta Ta Ta Ta Sa Sa Tb Tb Tb Tb Tb Tb Tb Tb Tb Tb Tb Tb Sb Sb Pb Pa

PCM 2 Ta Ta Ta Ta Ta Ta Ta Ta Ta Ta Ta Ta

PCM 3 Tb Tb Tb Tb Tb Tb Tb Tb Tb Tb Tb Tb Sb Sb Pb

RadioSiteMask Site A 1 1 1 1 1 1 1 1 1 1 1 1 1 1 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0

RadioSiteMask Site B 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 1 1 1 1 1 1 1 1 1 1 1 0 0 0 0 0 0

Table 14: PCM T1 RadioSiteMask

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

PCM 1 Ta Ta Ta Ta Ta Ta Ta Ta Ta Ta Ta Ta Sa Sa Tb Tb Tb Tb Tb Tb Sb Sb Pb Pa

PCM 2 Ta Ta Ta Ta Ta Ta Ta Ta Ta Ta Ta Ta Tb Tb Tb Tb Tb Tb

PCM 3 Tb Tb Tb Tb Tb Tb Sb Sb Pb

PCM 4 Tb Tb Tb Tb Tb Tb

RadioSiteMask Site A 1 1 1 1 1 1 1 1 1 1 1 1 1 1 0 0 0 0 0 0 0 0 0 0

RadioSiteMask Site B 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 1 1 1 1 1 0 0 0 0

BSC S444 S222PCM1

PCM2

PCM3

PCM4

Site A Site B

TEI 0 TEI 1



PE /IRC/APP/0079 01.08 / EN 12/04/99

Example 2

This other example concerns the Hub&Spoke configuration. Four omnisectorialBTSs are linked in order to save transmission costs.

Figure 7: Hub&Spoke example

The traffic of the BTS A is equally shared between the 2 PCMs, while the traffic ofthe other BTSs is supported by the PCM1 or the PCM2 but not shared.

Table 15: PCM E1 RadioSiteMask

TS number 31 30 29 28 27 26 25 24 23 22 21 20 19 18 17 16 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0

PCM 1 Ta Ta Ta Ta Ta Ta Tb Tb Tb Tb Tb Tb Pb Pa

PCM 2 Ta Ta Ta Ta Tc Tc Tc Tc Tc Tc Tc Tc Td Td Td Td Pd Pc

RadioSiteMask Site A 1 1 1 1 1 1

RadioSiteMask Site B 1 1 1 1 1 1

RadioSiteMask Site C 1 1 1 1 1 1 1 1

RadioSiteMask Site D 1 1 1 1

Table 16: PCM T1 RadioSiteMask

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

PCM 1 Ta Ta Ta Ta Ta Ta Tb Tb Tb Tb Tb Tb Pb Pa

PCM 2 Ta Ta Ta Ta Tc Tc Tc Tc Tc Tc Tc Tc Td Td Td Td Pd Pc

RadioSiteMask Site A 1 1 1 1 1 1

RadioSiteMask Site B 1 1 1 1 1 1

RadioSiteMask Site C 1 1 1 1 1 1 1 1

RadioSiteMask Site D 1 1 1 1

BSC O5

O3

PCM1

PCM2

PCM3

PCM4

Site A

Site B

TEI 0

TEI 1

O4

Site C

TEI 1

O2

Site D

TEI 2

PCM5



PE /IRC/APP/0079 01.08 / EN 12/04/99

6.1.5 RADIOSITEMASK EXTENSION STRATEGY

The future expansion of the network may be taken into account when dimensioningthe RadioSiteMask. It will make the network roll-out easier.

The radioSiteMask parameter is a class 2 parameter located in the btsSiteManagerQ3 object. It means that this parameter can only be set when the object is locked andthe parent bsc object is unlocked. Therefore, the modification of the radioSiteMaskwill involve interruption of service.Moreover, forecasting the future extension will avoid some complex RadioSiteMaskconfigurations that are difficult to manage.

Different configuration strategies can be applied according to the knowledge of theextension politics of the operators.

First strategy:

Assumption: The number of the future additionnal DRXs in a BTS can be assessed.

In this case, it will be of interest to increase the RadioSiteMask. This method allowsextensions without requiring the reconfiguration of the RadioSiteMask (nointerruption of service).

Figure 8: Example

The site A is composed of 6 DRXs in a cabinet. One cabinet can contain up to 8DRXs. Therefore, it could make sense to foresee the introduction of the 2 otherpossible DRXs. It would facilitate their introduction and avoid any interruption ofservice for the two sites.

BSC S222 O2PCM1 PCM2

Site A Site B

TEI 0 TEI 1



PE /IRC/APP/0079 01.08 / EN 12/04/99

Ta Traffic TS site ATb Traffic TS site BSa Secondary LAPD site APa Primary LAPD site APb Primary LAPD site B

Of course, if Site A is composed of three radio cabinets, it does not make sense todimension the RadioSiteMask for a 3S888. Another strategy has to be considered.

Second strategy

Assumptions:Nortel has no knowledge of the future number of added DRXs.Nortel is convinced that the operator will not add any other BTSs in aD&I configuration.

In such case, the RadioSiteMask can be defined as indicated in Table 18.

Ta Traffic TS site ATb Traffic TS site BSa Secondary LAPD site APa Primary LAPD site APb Primary LAPD site B

This configuration allows to easily increase capacity in the both site. The introductionof additional DRX in a site will not perturb the other one, only one RadioSiteMask isimpacted. Moreover the two RadioSiteMask stay simple and easy to manage.

The drawback is that it will be difficult to add a BTS in a D&I configuration, becausethe RadioSiteMask of the site B must be modified (interruption of service).

Table 17: RadioSiteMask (first strategy)

TS number 31 30 29 28 27 26 25 24 23 22 21 20 19 18 17 16 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0

PCM 1 Ta Ta Ta Ta Ta Ta Ta Ta Ta Ta Ta Ta Sa Sa Tb Tb Tb Tb Pb Pa

PCM 2 Tb Tb Tb Tb Pb



Table 18: RadioSiteMask (second strategy)

TS number 31 30 29 28 27 26 25 24 23 22 21 20 19 18 17 16 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0

PCM 1 Ta Ta Ta Ta Ta Ta Ta Ta Ta Ta Ta Ta Sa Sa Tb Tb Tb Tb Pb Pa






PE /IRC/APP/0079 01.08 / EN 12/04/99

Third strategy

Assumption: Nortel has no information about the extension policy.

If Nortel has any information, the two previous strategies are not recommended. The"normal" configuration with the engineering rules of page 37 may be followed.

The BTS introduction in a Drop&Insert configuration will be easy. Moreover, it is alsopossible to introduce additional DRXs without interruption of service for the secondsite.

Ta Traffic TS site A Pa Primary LAPD site ATb Traffic TS site B Pb Primary LAPD site BSa Secondary LAPD site A

The drawback is that some RadioSiteMask can be quite complex and it will becomemore and more difficult to make them evolve.

6.1.6 ADDITINAL FEATURE OF TDMA/ABIS MAPPING CONFIGURATION FOR V11

A new V11 feature secures the Abis interface. FM844 "Traffic Channel Defense"allows to reconfigure the TDMA according to their priority in case of PCM failure fora multiPCM site, as long as one PCM is available (refer to [R04]).

If the following requirements are fulfilled:

• the PCMs are not full,• if the rentalfees are per used PCM and not per used TS,

then it could make sense to increase the radioSiteMask. It will allow more TSreconfigurations and then to lose less traffic channels. Moreover it could facilitate theintroduction of new DRXs.

The drawback is that the evolution of the network could be more difficult (forexample, adding a BTS in drop&insert). There is a trade-off between quality ofservice and flexibility.

For further information on this feature, please refer to the V11 FEI [R04].

Table 19: RadioSiteMask (Third strategy)

TS number 31 30 29 28 27 26 25 24 23 22 21 20 19 18 17 16 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0

PCM 1 Ta Ta Ta Ta Ta Ta Ta Ta Ta Ta Ta Ta Tb Tb Tb Tb Ta Ta Ta Ta Sa Sa Pb Pa






PE /IRC/APP/0079 01.08 / EN 12/04/99

6.2 HUBS

6.2.1 CROSS-CONNECT

Since the V8 system release, a new feature is available: TEI decorrelation. It allowsthe simulation of a Drop&Insert function from the BSC point of view, without usingthe BTS in Drop&Insert configuration.

The TEI of the BTS can be the same, then since V8, the TEI number and the"Rendez-vous TS" are decorrelated on the BSC side. The number of the "Rendez-vous TS" is configurated by the pcmTimeSlotNumber parameter on the MMI interface.pcmTimeSlotNumber is located in the btsSiteManager Q3 object.

Figure 9: Cross-connect configuration

For the BTS, the installation is easier because all the sites have the sameconfiguration (Star with a TEI = 0). For the BSC, the 3 sites are in drop and insert sothe drop and insert rules must be respected on the BSC side. The choice of the TSfor the signalisation must be done in accordance with the crossconnectconfiguration.

Figure 10: Crossconnect configuration



PE /IRC/APP/0079 01.08 / EN 12/04/99

The traffic TS must be at the same place (TS number) on the two sides of thecrossconnect. This rule does not concern the primary signalling TS which has a fixedposition on the BTS side (TEIBCF+1).

Ta Traffic Ts site ATb Traffic Ts site BTc Traffic Ts site CPa Primary LAPD site APb Primary LAPD site BPc Primary LAPD site CSwitch

6.2.2 SWITCH

Hubs can act as switch for redundancy purpose. The main advantage of thisarchitecture is that in case of PCM1 failure, the hub1 is able to switch on theredundant PCM2 without loosing the communications.

Figure 11: Architectuire with Switch

It can be implemented with digital cross-connect such as PDMX-E (Nortel product).

Table 20: RadioSiteMask configuration with crossconnect

TS number 31 30 29 28 27 26 25 24 23 22 21 20 19 18 17 16 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0

PCM A Ta Ta Ta Ta Pa

PCM B Tb Tb Tb Tb Pb

PCM C Tc Tc Tc Tc Pc

PCM D Ta Ta Ta Ta Tb Tb Tb Tb Tc Tc Tc Tc Pc Pb Pa



RadioSiteMask Site C 0 0 0 0 0 0 0 0 1 1 1 1 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0

BSC

BTS

BTS

BTS

Hub1 Hub2

PCM1

PCM2



PE /IRC/APP/0079 01.08 / EN 12/04/99




PE /IRC/APP/0079 01.08 / EN 12/04/99

7 TRANSMISSION MEDIUM

7.1 CLOCK

Timing requirements according to G811 are:

One characteristic defines the quality of the PCM clock for the BSS sub-systems andespecially for the BTS.

There are two requirements to consider:• The requirement for a PCM: 50 ppm (see G732).• The requirement for the BTS in order to generate a reference time for radio

interface.

The BTS uses the clock reference from the network to generate a 5*10 -8 precisiontiming reference for the radio interface.

Long-term accuracy recommended for PCM E1 (2,048 MHz) and PCM T1 (1,544MHz):

| ∆f/f | = 10 -9 or 0,001 ppm

This characteristic assures a good transmission quality for BTS frequencies allowingthe mobile connections and avoiding the disturbance of the adjacent frequencies.

Note: it is not necessary that all GSM sub-systems are synchronized with the sameclock, but that they respect the recommendations defined above.

Table 21: Timing requirements

Time | ∆f/f |

≥ 98,89% | ∆f/f | ≤ 10 −11

≤ 1% 10−11 < | ∆f/f | ≤ 2∗10−9

≤ 0,1% 2∗10 −9 < | ∆f/f | ≤ 5∗10 −7

≤ 0,01% 5∗10 −7 < | ∆f/f |



PE /IRC/APP/0079 01.08 / EN 12/04/99

7.2 TRANSMISSION QUALITY REQUIREMENTS

To maintain the PCM quality to a good level, BER shall not exceed 10E-4.

To not disturb the voice quality, BER shall be maintained at or above 10E-6.

PCM unavailibility also has a big impact on the BSS. The unavailibility is determinedby errors detected by the DDTI board. The different types of error are:

For E1 PCM links :• No signal• Signal Indicator Alarm error• Frame alignment loss• Synchronization loss• Frame error• Distant alarm indicator error• CRC error

For T1 PCM links :• No signal• Signal Indicator Alarm error• Frame alignment loss• Synchronization loss• Distant alarm indicator error

The time duration of the PCM unavailibility is determined by the number of ErroredSeconds (ES if at least an error occurs for 1 second). For example, if the signal islost for 3.1 seconds, the PCM unavailibility time could be 5 seconds.

SIGNAL SIGNAL

ES ES ES ES ES



PE /IRC/APP/0079 01.08 / EN 12/04/99

The time duration of the PCM unavailability impacts the BTS in different ways:

PCM unavailibility < 5 seconds

When the BSC-BTS link is interrupted during less than 5 seconds (5 ErroredSeconds), nothing happens. The communications are disturbed, but not lost.

PCM unavailibility between 5 seconds and 30 minutes

A timer exists that triggers a defense BSS mechanism. If the BSC-BTS link isinterrupted for more than this timer, the BSC will try to find another PCM toreestablish the contact. When the contact is reestablished, the BSC will lead in theBTS to a reset of PCM boards and a BCF and TRX reconfiguration.

Today this timer is set to 5 seconds, which allows fast recovery in case of a realfailure, and fast alarm reporting, and however tolerates short transient link outagesoften encountered especially with microwaves links. This timer is therefore a trade-off between fast recovery and tolerance to transient faults.

PCM unavailibility > 30 minutes

If the interruption lasts for more than 30 minutes, the BTS resets itself, and will beredownloaded and reconfigured when the link is up again. In case of DRX (S8000 orS2000H/L) or AMNU/DCU4, the download procedure is reduced. In fact, thesoftware is not downloaded, but only checked.

The reconfiguration and reboot time depend on the BTS configuration. This kind ofinformation can be found in the document "Performance Tests Results Report"([R20]) which gives a summary of performance tests performed in PIV.

F PCM unavailibility (BER > 10E-3) for less than 5 seconds leads to disturb thecommunications.

F PCM unavailibility beween 5 seconds and 30 minutes leads to lose current com-munications plus a BTS reconfiguration time (BTS dependent, refer to [R20]).

F PCM unavailibility of more than 30 minutes leads to a complete reboot of the BTSwhich could last several minutes depending on the configuration (refer to [R20]).



PE /IRC/APP/0079 01.08 / EN 12/04/99

7.3 CSU

The CSU equipment is designed to be inserted between the Abis link provided by theoperator and the BCF subrack. Its purpose is to test and recalibrate the incoming andoutgoing signal and ensure that it meets the recommendations. The equipmentincludes a set of alarms displayed on the CSU front panel. Any alarm condition (orpower failure) releases a single pole alarm relay connected to the user alarms of theBTS.

Three types of CSU equipment can be ordered: CSU T-serv II, CSU T-smart, andCSU MPATH. The MPATH CSU offers additional features (such as SNMPmanagement) compared to other types of CSU.

The CSU equipment is designed for T1 PCM and is mandatory for the US market.

7.4 HDSL

7.4.1 INTRODUCTION

HDSL is a technology that allows to convey, on a few kilometers, a PCM signal overordinary twisted pairs. This technology becomes more and more popular, as a cheapsolution to provide PCM links to remote locations. This applies generally to the Abislink, including Drop&Insert configurations.

Figure 12: HDSL solution

For short distances (up to 1.5 Km), only one wires twisted pair is needed. Two wirestwisted pairs are required for longer distance (up to 4 Km). The distances depend onthe modems and on the quality of the twisted pair wires. Therefore the values givenabove are only for indication purposes and must not be communicated to customers.

BSC BTS

master HDSL modem

slave HDSL modem

2 twisted pairs4 shielded pairs 4 shielded pairs

PCM PCMHDSL



PE /IRC/APP/0079 01.08 / EN 12/04/99

7.4.2 HDSL ISSUES

HDSL modems use a very complex synchronization scheme based on a master-slave configuration. The master HDSL modem is on the BSC side and the slave oneis on the BTS side. The consequence is that any short link drop or click disturbancyleads to long link unstability. Depending on the modem, 1 second interruption maytranslate up to 15 seconds.

The timer that triggers a defense BSS mechanism is set to 5 seconds (refer tosection 7.2 ). This value may no longer be the right trade-off between fast recoveryand tolerance to transient fault for the HDSL link. For the network that uses HDSL,a timer value of 15 seconds seems to be a better trade-off for the sake of the linkstability (but QOS impact). This specific parameter setting of the BSS defensemechanism is not mandatory. Some HDSL modems work properly with the defaultconfiguration.

Note that the timer value applies to all PCM links of the BSC and not only to the HDSLlinks.

7.4.3 HDSL MODEMS

The HDSL modems are systematically tested by R&D in order to remove modemswhich are suspected to lead problems on the field. The list of the recommendedHDSL modems and the list of the inadvisable ones can be found in the document"HDSL modem layer1 qualification" ([R21]).

For all modems considered OK, a very short disturbance on the Abis line (i.e. :1 second cut) leads to unavailability of the link for more than 10 seconds.



PE /IRC/APP/0079 01.08 / EN 12/04/99

7.5 MICROWAVES

7.5.1 MICROWAVE DESIGN GUIDELINES

MW link have the following advantages over leased lines:

Meet superior reliability, allow total control over them, easy expansion, and rapiddeployment.

However, the following design guidelines must be taken into account:

• L.O.S (line of Sight),• Distance,• Parabolic antennas,• Frequency dependence,• Interference limitation.

L.O.S. needed

That means that a MW link is terrain dependant, and sometimes a link cannot beinstalled. Indeed the clearance has to be 60% of the first Fresnel zone, plus asecurity factor (5 or 6 m) for errors on terrain data. The 60% F1 is calculated forstandard atmosphere (k=4/3) and the atmosphere can change, needing the link abetter clearance. In this case a calculation can be done with k=2/3 and 50% F1.

Distance

The effects of rain and multipath limit the distance a link can cover, so thatsometimes a repeater is needed to cover this distance. In order to calculate theunavailability due to rain, the rain zone where the link is going to be installed, has tobe known ; this will give the rain rate that is exceeded the 0.01% of the annual time(i.e. k rain zone is 42 mm/h).

Figure 13: Microwave solution



PE /IRC/APP/0079 01.08 / EN 12/04/99

When designing a link, the availability (unavailability) is an objective that is fixed bythe operator in order to meet its quality requirements. For example, the availabilitydue to propagation in a 1+0 (nonprotected) can be 99.99% of the annual time; for thisobjective, if the rain zone is k (42 mm/h), in 23 GHz up to 13 Km can be covered(0.6 m antennas at both sites and vertical polarization), and in 38 GHz up to 6 Km(0.6 m antennas at both sites and vertical polarization).

Parabolic antennas

Parabolic antennas must be installed. Wind loadings have to be considered on thetower, or the place where the antenna is going to be installed. The tilt and twist of thetower, that increases with the height, can affect the alignment of the antenna,reducing the receive signal level, and consequently the fade margin.

Frequency dependence

Sometimes it is difficult to get a channel from the local government; normally thisdepends on the working band (15 GHz, 23 GHz etc..).

Interference limitation

There is a limitation in the number of links that can converge at one point(concentrator) due to interference mechanism. In digital MW links the interferencereduces the threshold, which means that the fade margin decreases and the link willbe unavailable for more time than the time it was calculated for. Alternate polarization(cross polarization discrimination) and high gain antennas (more directivity) canoffset these effects.

For further information, please refer to the web pages of the transmissions group atthe following URL address:

http://136.147.68.68/ned/ND_AE/ND/Transmission/Transmission.html



PE /IRC/APP/0079 01.08 / EN 12/04/99

7.5.2 MICROWAVE QUALITY REQUIREMENTS

The ITU-T G.821 defines different grades of service for the microwavetransmissions: high grade (HG), medium grade (MG) and local grade (LG).

Figure 14: Reference communication of ITU.

The performance of the grade of service can be estimated by 3 parameters:

F Degraded Minutes:DM if BER > 10-6 for 1 minute.

F Severely Errored Seconds:SES if BER > 10-3 for 1 second.

F Errored Seconds:ES if at least an error occurs for 1 second.

The performance objectives of these 3 grades of service are:

Figure 15: Performance objectives:

27500 km1250 km1250 km 25000 km

Localgrade

Localgrade

Mediumgrade

Mediumgrade

Highgrade

Global< 10%

< 0.2%

< 8%

HG< 4%

< 0.04% *

< 3.2%

MG< 1.5%

< 0.015% *

< 1.2%

LG< 1.5%

< 0.015%

< 1.2%

Note*: 0.05% can be added if m/w is used.DM: Min. at 10E-6; SES: Sec. at 10E-3; ES: Sec. with errors.

PERFORMANCE OBJECTIVES:

DegradedMinutesSeverelyErroredSeconds ErroredSeconds



PE /IRC/APP/0079 01.08 / EN 12/04/99

Depending on the configuration local or medium grade links are recommended forAbis interface. Medium grade quality is 50% to 100% more expensive than localgrade as it requires redundant equipment. It must be proposed only if specified bycustomer.

7.5.3 MICROWAVE CONFIGURATIONS

It is possible to combine the drop and insert functionality of the BTS product and themicrowaves product in order to insure the transmission security and capacity. Thefollowing configurations are given as example.

Figure 16: Chain Drop&Insert with microwaves

Figure 17: Loop Drop&Insert with microwaves

Central Office

BSCTCU

medium or local grade

DMS Switch

BTS BTS BTS

Central Office

TCUDMS SwitchBSC

local grade ringlocal or medium grade

BTS 1 BTS 2 BTS 3

BTS 5 BTS 4



PE /IRC/APP/0079 01.08 / EN 12/04/99

Figure 18: Hub and Spoke with microwaves

The minimum capacity of the microwaves equipment is 2 E1 PCM links. Therefore, from the BSC point of view, the Loop D&I implementation (fig. 17) is seen as below:

Figure 19: Abis configuration with microwaves on BSC side

local gradelocal or medium grade

Central Office

TCUDMS SwitchBSC

BTS

BTSBTS

BTS

BTS

BTS S222

BSC

BTS1

BTS2

BTS3

BTS4

BTS5



PE /IRC/APP/0079 01.08 / EN 12/04/99

7.5.4 MICROWAVE EQUIPMENT REDUNDANCY

PCM link failure can be more diverse than for a cable support. Two main events canoccur: either an equipment failure, either a signal fading due to rains or multipath.

In all cases, all the PCM carried between the two radio systems are brought down.A failure of only one PCM link is not possible, contrary to the LL cable solution.

PCM link failure due to equipment can be minimized by redundant configuration.

Figure 20: Typical non-protected and protected microwave equipment architecture

Two protected configurations can be considered:

• The first one with redundant DIU and RFU with a single antennae (a waveguide coupler must be used).

• The second one uses two antennas without wave guide coupler. It allows toavoid the PCM link failure due to antennea falling out of alignment.



PE /IRC/APP/0079 01.08 / EN 12/04/99




PE /IRC/APP/0079 01.08 / EN 12/04/99

8 BSC DIMENSIONING

8.1 BSC TYPE

The following table gives the board configuration related to Abis interface for eachavailable BSC type.

*The BSCB board is optional for the BTS LAPD concentration. If this option is not chosen, the num-ber of BSCB boards required is zero.

The number of BSCB boards shown in the table indicates the maximum number of BSCB boards foreach type of BSC. The minimum number of BSCB boards is 2. The quantity of boards depends onthe number of LAPD channels (or sites) to be concentrated.

One board is reserved for redundancy purpose (+1).

** There is a maximum of 24 DDTI boards per BSC12000 (whatever the product version is: 1201/1202/1203/1204/1205). The basic configuration provides 10 DDTI boards. But, depending on theneeds, it is possible to add DDTI units up to 24.

For the BSC 6000 product family, there are 6/10/14/20/24 DDTI boards depending on the productversion 602/604/606/608/610 respectively. These numbers are fixed.

Table 22: Product range

Architecture BSC 6000 BSC 12000

Type 1 2 3 4 5 1 2 3 4 5

DDTI(**) 6 10 14 20 24 24 24 24 24 24

BSCB(*) 0 0 0 11+1 11+1 11+1 11+1 11+1 11+1 11+1

SICD 2 4 6 8 10

SICD8 1 2 3 4 5



PE /IRC/APP/0079 01.08 / EN 12/04/99

8.2 SICD/SICD8V BOARDS

8.2.1 LIMITATION RULES

SICD limitation rules

The limitation rules for the SICD board are:

vOne SICD board has 4 ports (hardware design). One SICD board can manage upto 4 physical channels of LAPD (concentrated with BSCB or non concentrated).

vOne LAPD equipment (SICD ports) supports up to 10 TEI. Note that one TCUcorresponds to one TEI, one BCF corresponds to one TEI, and one TRXcorresponds to one TEI.

v16 is the maximum number of TDMA per SICD due to traffic load.

vAll the LAPD equipment are reserved for the Abis interface except the fourth port(port 3) of the SICD 0 which is used for the TCU (by convention).

SICD8V limitation rules

The limitation rules for the SICD8V board are:

vOne SICD board has 8 ports (hardware design). One SICD board can manage upto 8 physical channels of LAPD (concentrated with BSCB or non concentrated).

vOne LAPD equipment (SICD ports) supports up to 15 TEI. Note that one TCUcorresponds to one TEI, one BCF corresponds to one TEI, and one TRXcorresponds to one TEI.

v64 is the maximum number of TDMA per SICD due to traffic load.

vAll the LAPD equipment are reserved for the Abis interface except the fourth port(port 3) of the SICD8V 0 which is used for the TCU (by convention).

8.2.2 PARENTING RULES

To avoid overload on one SICD due to high spot traffic, use the following rules forparenting.

vTwo neighbor sites must be on two different SICDs.

vTwo cells of a same site must be on two different SICDs. Of course this conditioncan only be applied if the two cells are mapped on two different LAPD channels.

A SICD8V board does the same job as a SICD, but the processor is more powerful.Furthermore, the inhomogenous load on the various SICD8V has less impact withSICD8V than with SICD because the load is only split onto 5 boards as opposed to10 for SICD.



PE /IRC/APP/0079 01.08 / EN 12/04/99

8.2.3 LOOK-UP TABLES

*This number can be worked out from nb SICD * max TDMA per SICD.

8.3 BSCB AND TSCB BOARDS

Use of BSCB is optional. If this option is not chosen, the number of BSCB boardsrequired is zero. The minimum number of BSCB boards is 2. The quantity of boardsdepends on the number of LAPD channels (or sites) to be concentrated.

The associated parameter is a class 0 parameter (xSCBConfiguration in the bscobject). Therefore, every time a board is added, the BDA needs to be rebuilt.

The BSC does not have a dedicated board used for redundancy, but manages a poolof BSCB boards. When one BSCB fails, the BSC reconfigures the wholeconfiguration of the failed BSCB onto a free BSCB board (one without any LAPDmapped on it).

When new concentrated LAPD terminals are declared and LAPD channel locationsare moved from one SICD to another, it is very important to check that a BSCBremains free.

Table 23: SICD limitations


Type 1 2 3 4 5 1 2 3 4 5

SICD/SICD8V board 2 4 6 8 10 1 2 3 4 5

LAPD eqpt 8 16 24 32 40 8 16 24 32 40

LAPD eqpt for Abis 7 15 23 31 39 7 15 23 31 39

TEI per LAPD eqpt 10 10 10 10 10 15 15 15 15 15

TDMA per SICD/SICD8V 16 16 16 16 16 64 64 64 64 64

TDMA* 32 64 96 128 160 64 128 192 256 320

F The BSCB boards can be the bottleneck of the BSC in some configurations.Therefore it is very important to follow the rules describe in the document "BSCBEng’g Information: Load monitoring and optimization" ([R22]).



PE /IRC/APP/0079 01.08 / EN 12/04/99

Figure 21: Dimensioning the Abis interface with LAPD concentration

A BSCB board processes the concentration of 12 unconcentrated links to 3 (3 times4 LAPD unconcentrated into 1 LAPD concentrated). The limit of 10 TEIs per SICDport (BCF+TRX) or 15 TEIs per SICD8V port is still in effect.

*Number of sites per BSC, depending on the number of SICD and BSCB (with BSCB redundancy).

Table 24: Maximum number of sites per BSC


Type 1 2 3 4 5 1 2 3 4 5

SICD/SICD8V board 2 4 6 8 10 1 2 3 4 5

LAPD eqpt 8 16 24 32 40 8 16 24 32 40

LAPD eqpt for Abis 7 15 23 31 39 7 15 23 31 39

BSCB 0 0 0 11+1 11+1 11+1 11+1 11+1 11+1 11+1

max number of sites (*) 7 15 23 124 138 28 60 92 124 138

BTS sites

BSCB BSCB BSCB

SICD8V SICD8V

Abis Interface+

BSC internal connectivityMax. of 12 non-concentratedLapD channels used per BSCB board

Max. of 3 concentratedLapD channels used per BSCB board

Max. of 8 LapD Equipment usedper SICD8V board (4 LapD equipmentper SICD board)



PE /IRC/APP/0079 01.08 / EN 12/04/99

8.4 DDTI BOARDS

Since the BSC extracts the synchronization clock from PCM 0, 2, 4, and 6, thesespans are used only for the Ater interface. The others can be usedindiscriminately either for the Abis or the Ater interface but must use somespread convention.

Spread convention nc. 1In order to minimize the number of remainning PCMs when a board fails, it is best tospread the spans of a BTS on different DDTIs.

Spread convention nc. 2Use the same previous rule when configuring Ater PCMs. Avoid the configurationof two Ater PCMs on a same DDTI board.

A DDTI board handles two PCMs which are connected to port 0 and port 1.

PCM_Number = 2*DDTI_Number + Port_Number

Table 25: PCM allocation for the BSC6000 Type5

PCM Number Allocation

0, 2, 4, 6 Ater

1, 3, 5, 7 to 47 Ater or Abis

F The use of PCM 0, 2, 4, 6 for Abis interface may lead serious synchronizationproblems for the whole BSS. So, this configuration is forbiden.



PE /IRC/APP/0079 01.08 / EN 12/04/99

9 APPENDIX

This configuration has been tested in a network. This interesting configuration usescross-connect and Hub&Spoke configuration.

Figure 22: Example of complex configuration

BSC

S11

Cross-connect S111

S111

S111

S111

S11

S111 S11 S111TEI0

TEI1

TEI1 TEI2 TEI3 TEI4

TEI3

TEI2

TEI4



PE /IRC/APP/0079 01.08 / EN 12/04/99

END OF DOCUMENT

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