BSS Dimensioning Rules B6.2

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BSS B6.2 Configuration description

Alcatel File Reference Date Edition Pageb62_jv_2000.doc 3DF 00928 0001 DSZZA 03/01/2000 03 1

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BSS B6.2 CONFIGURATIONDESCRIPTION

DIMENSIONING RULES


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TABLE OF CONTENTS

1 HISTORY.............................................................................................................................................................6

2 REFERENCE DOCUMENTS............................................................................................................................7

3 SCOPE..................................................................................................................................................................7

4 AIR INTERFACE ...............................................................................................................................................8

4.1 RADIO CHANNELS CONFIGURATION ...................................................................................................................8

4.1.1 GPRS Impact .......................................................... ..................................................... .............................8

4.1.2 Radio channels type ......................................................... .............................................. ..........................8

4.1.3 Rural Configurations....................................................... ................................................. ........................9

4.1.4 Urban Configurations ............................................................ .......................................... ......................10

4.1.5 Urban Dense Configuration..... ............................................................ ...................................... ............114.2 TRAFFIC AVAILABLE ........................................................................................................................................12

5 BTS CONFIGURATIONS................................................................................................................................13

5.1 EVOLIUMTMA9100 BTS RADIO SOLUTION ..................................................................................................13

5.1.1 General Product presentation........................................................ ............................................ ............13

5.1.2 Evolium BTS........................................................ ............................................................. ......................135.1.2.1 Functional description................................................................................................................................... 13

The EvoliumTM A9100 BTS is made of the following components:.................................................................13

5.1.3 Evolium Evolution BTS ........................................................... ............................................................. ..145.1.3.1 Overall architecture ....................................................................................................................................... 15

5.1.4 High power GSM 1800...................... ............................................................ ....................................... ..16

5.1.5 Single antenna..................................................... ....................................................... ............................16

5.1.6 Low losses ........................................................ ........................................................ ..............................165.1.7 TMA and REK solutions ......................................................... ............................................ ....................16

5.1.8 Multiband configurations............................................................ ...................................... .....................175.1.8.1 Multiband BTS.............................................................................................................................................. 17

5.1.8.2 Multiband cell ............................................................................................................................................... 17

5.2 G2 BTS IN B6.2...............................................................................................................................................18

5.3 G1 BTS IN B6.2...............................................................................................................................................18

5.4 BTS CONFIGURATIONS SUMMARY ...................................................................................................................18

6 ABIS LINKS ......................................................................................................................................................20

6.1 ABIS NETWORK TOPOLOGY ..............................................................................................................................21

6.2 MEDIUM OF ABIS NETWORK TRANSPORT .........................................................................................................21

6.3 ABIS TRAFFIC ...................................................................................................................................................22

6.4 SIGNALLING SUBMULTIPLEXING SCHEMES .......................................................................................................236.4.1 Presentation of concept................................................................................................... .......................23

6.4.2 16K Static multiplexing ................................................................................................... .......................246.4.2.1 Limitations and Requirements............................................................................................ ........................... 24

6.4.3 64K statistical multiplexing.............................................................................................. ......................256.4.3.1 Full Rate TRE........................................................................................................... ..................................... 25

6.4.3.2 Dual Rate TRE ........................................................................................................... ................................... 26

6.4.3.3 Limitations and requirements............................................................................................ ............................ 26

6.4.4 16K statistical multiplexing.............................................................................................. ......................266.4.4.1 Limitations and requirements............................................................................................ ............................ 26

6.5 ABIS MAPPING RULES .......................................................................................................................................27

6.5.1 Support of external cross-connect......... ............................................................ ................................... ..27

6.5.2 Mapping techniques ........................................................... ............................................. .......................28

6.5.3 B5 BSC G1 Mapping ....................................................... .................................................. .....................28


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6.5.3.1 Star Mapping (Appendix1)............................................................................................................................ 29

6.5.3.2 Closed Catalogue mapping (Appendix1)....................................................................................................... 29

6.5.3.3 B5 Free mapping ........................................................................................................................................... 29

6.5.4 B6.2 BSC G2 Free Mapping......................................................... ......................................... .................30

6.5.4.1 Free mapping rules ............................................................................................................................................... 30

7 G2 BSC CONFIGURATIONS .........................................................................................................................31

7.1 OVERVIEW .......................................................................................................................................................31

7.2 ABIS TSU CONNECTIVITY................................................................................................................................32

7.2.1 Rules ...................................................... ............................................................ .....................................327.2.1.1 Allocation of TSL link to TCUC................................................................................................................... 32

7.2.1.2 Allocation of TRX and BTS to TCUC.......................................................................................................... 32

7.2.1.3 Allocation of TRX and BTS to TSU ............................................................................................................. 33

7.2.1.4 Maximum number of TRX............................................................................................................................ 33

7.2.1.5 Maximum number of BTS/cells .................................................................................................................... 33

7.2.2 G2-BSC Half Rate Flexibility ...................................................... ...........................................................34

7.2.3 Recommendations......................................................... .................................................... ......................34

7.3 ATER TSU CAPACITY.......................................................................................................................................357.3.1 Rules ...................................................... ............................................................ .....................................35

7.3.1.1 Multiplexing on Ater link.............................................................................................................................. 35

7.3.1.2 Number of channels and interfaces................................................................................................................ 35

7.3.1.3 SS7 links dimensioning................................................................................................................................. 35


7.4 PROCESSOR LOAD ............................................................................................................................................37

7.4.1 Rules ...................................................... ............................................................ .....................................37


8 G1 BSC CONFIGURATIONS .........................................................................................................................38

8.1 OVERVIEW .......................................................................................................................................................38

8.2 ABIS CONNECTIVITY.........................................................................................................................................38

8.2.1 Rules ...................................................... ............................................................ .....................................388.2.1.1 Allocation of TRX......................................................................................................................................... 38

8.2.1.2 Allocation of BTS and cells .......................................................................................................................... 39

8.3 ATER CAPACITY ...............................................................................................................................................39

8.3.1 Rules ...................................................... ............................................................ .....................................398.3.1.1 Multiplexing on Ater link.............................................................................................................................. 39

8.3.1.2 Number of channels and interfaces................................................................................................................ 40

8.3.1.3 SS7 links dimensioning................................................................................................................................. 40


8.4 PROCESSORS LOAD ..........................................................................................................................................40

9 A935 MFS CONFIGURATIONS.....................................................................................................................41

9.1 OVERVIEW .......................................................................................................................................................41

9.2 CONSTRAINTS ..................................................................................................................................................429.2.1 Hardware support ......................................................... ................................................. ........................42

9.2.2 Rules ...................................................... ............................................................ .....................................429.2.2.1 GPRS-MFS In BSC-TC Configurations........................................................................................................ 42

9.2.2.2 BSS/MFS Connectivity................................................................................................................................. 42

9.2.2.3 GPRS BTSs................................................................................................................................................... 42

9.2.2.4 OMC-R/MFS Connection ............................................................................................................................. 43

9.3 A935 MFS ARCHITECTURE .............................................................................................................................43

9.4 A935 MFS DIMENSIONING ..............................................................................................................................43

9.4.1 GPU Dimensioning ........................................................ ............................................................ ............44

9.4.2 GPU interfaces dimensioning............................................................... ..................................................44

9.4.3 Method for dimensioning the interface from the BSC to the A935 MFS................................................47

10 ATERMUX LINKS...........................................................................................................................................48


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10.1 G2 MULTIPLEXING .......................................................................................................................................48

10.2 3:1 MUTIPLEXING.........................................................................................................................................49

10.2.1 Characteristics ...................................................................................................................................49

10.2.2 Mapping consequences......................................................................................................................49General mapping............................................................................................................................................................... 50

10.2.2.2 Mapping rules................................................................................................................................................ 51

10.2.2.3 CICs number ................................................................................................................................................. 51

10.3 4:1 MULTPLIPLEXING ...................................................................................................................................51

10.3.1 Characteristics ...................................................................................................................................51

10.3.2 Mapping consequences......................................................................................................................5210.3.2.1 General mapping ........................................................................................................................................... 52

10.3.2.2 Mapping rules................................................................................................................................................ 53

10.3.2.3 CICs Number................................................................................................................................................. 53

10.4 COMPARISON 3:1 AND 4:1 WITH G2 BSC........................................................... .........................................53

10.5 RULES OF ATER INTERFACE BETWEEN MFS AND BSC ........................................................... .....................54

11 TC CONFIGURATIONS..................................................................................................................................55

11.1 G1 TC ........................................................... ........................................................... ...................................5611.1.1 Presentation .......................................................................................................................................56

11.1.2 Functional configuration ...................................................................................................................56

11.2 G2 TC ........................................................... ........................................................... ...................................57

11.2.1 Presentation .......................................................................................................................................57

11.2.2 Functional configuration ...................................................................................................................57

11.2.3 New TC G2 granularity......................................................................................................................58

11.3 G2.5 TC .......................................................... .......................................................... ..................................58

11.3.1 Topology ............................................................................................................................................58

11.3.2 Dimensionning...................................................................................................................................58

11.3.3 Extension............................................................................................................................................59

12 OMC-R 1353 RA CONFIGURATIONS .........................................................................................................60

DIMENSIONING RULES...............................................................................................................................................60

12.2 HW DESCRIPTIONS : 5 GENERIC CONFIGURATIONS .....................................................................................61

12.2.1 Server .................................................................................................................................................61

12.2.2 HMIS and Terminal. ..........................................................................................................................61

12.2.3 O&M Configuration...........................................................................................................................62

12.3 HW : OMC2 VERSUS OMC3 ......................................................................................................................63

12.4 OMC-R/BSC INTERCONNECTION ..................................................... ...................................................63

12.4.1 Collocated BSCs without router (via simples adapters on HIS ports) ...............................................64

12.4.2 Collocated BSCs via X25 switch (Newbridge) ...................................................................................64

12.4.3 Remote BSCs via PSDN (via modem)................................................................................................64

12.4.4 BSCs connection via Transcoder .......................................................................................................6512.4.4.1 X25 extraction on G1 TC .............................................................................................................................. 65

12.4.4.2 X25 extraction on G2 .................................................................................................................................... 6612.4.5 BSC CONNECTION VIA MSC ..........................................................................................................67

12.4.5.1 Characteristics ............................................................................................................................................... 67

12.4.5.2 Small configuration ....................................................................................................................................... 67

12.4.5.3 Large number of BSCs at MSC site .............................................................................................................. 68

12.4.5.4 Additional OMCRs for large networks................. ....................... ....................... ........................ ............. .... 69

12.4.5.5 Remote configuration ......................................................................................................................................... 70

12.4.5.7 Mixed local and remote MSC configuration....................................................................................................... 71

12.5 OMC-R/MFS INTERCONNECTION.............................. ........................................................... ...............72

12.5.1 MFS and OMCR collocated (via an external Hub)........................................................ ..................72

12.5.2 MFS and OMCR not collocated (via PSDN ) ..................................................................................7312.5.2.1 case of CISCO 2500 use................................................................................................................................ 73

12.5.3 Case of CISCO 4700 use....................................................................................................................7412.5.3.1 Principle ........................................................................................................................................................ 74

12.5.3.2 Main advantages............................................................................................................................................ 74


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12.5.3.3 Technical description .................................................................................................................................... 75

12.5.3.4 BSC OMC-R connection..................... ....................... ....................... ....................... ............... ................... 76

13 GLOSSARY.......................................................................................................................................................79

Appendix 1 : Star and closed catalogue mapping...............................................................................................81

03 03/01/2000

RCD/TD RCD/CO/PCS/NOP

ED DATE CHANGE NOTE APPRAISAL AUTHORITY ORIGINATOR


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1 HISTORY

Ed. 01 21/08/98 First Edition.

Ed 02 25/10/99

Second Edition

Update with :

OMC-R 1353 RA

GPRS

Moderation Factor

Ed 03 Proposal 1 01/01/2000

Third edition

Update with :

TC G2.5

HR Flexibility

Extended cell on G3BTS

Ed 03 Proposal 2 20/01/2000 Update according to review


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2 REFERENCE DOCUMENTS

[1] 3BK 10204 0467 DTZZA BSS Technical Feature List (Without GPRS)

[2] 3BK 11203 0039 DSZZA Transmission Functional Specification

[3] 3DC 20003 0012 UZZZA Dimensioning Rules for G2 BSC TC with BSS SoftwareB6.2

[4] 3DC 20003 0013 UZZZA Dimensioning rules for GPRS with BSS software B6.2

[5] 3BK 11203 0055 DSZZA GPRS Traffic Model and Performances

[6] 3BK 10204 0438 DTZZA General Packet Radio Service

[7] 3BK 17025 0124 PGZZA B6.2 BSS Configurations Rules

[8] 3DC 21006 0003 TQZZA Use of Moderation Factor for BSS traffic assessment

[9] 3BK 17025 0119 PGZZA BSS O&M Routing Configurations in B6.2

[10] 3DC 20003 0010 UZZZA G2 BSC Dimensioning Rules with the BSS SoftwareRelease B5

3 SCOPE

This document describes the BSS dimensioning rules in Release 6.2 (SMG28 andSMG29).

It gives general explanations about new hardware and software configurations and theirimpact in the various interfaces as regards dimensioning aspects. GPRS and statisticalmultiplexing on A-bis interface which are introduced in B6.2, are mainly impacting thisdocument since B5 edition.

TC A925 and BTS A9100 EVOLIUM BTS Evolutions should be introduced in B6.2.


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4 AIR INTERFACE

4.1 Radio Channels Configuration

4.1.1 GPRS Impact

GPRS radio time-slots (PDCH) are dynamically allocated according to the followingcustomer defined parameters:

MIN_PDCH_GROUP: Minimum number of PDCH TS per cell ( can be anyfrom 0 to 8)

The operator can ensure that minimum resources is dedicated to GPRS even ifthe cell is fully loaded with non GPRS traffic.

MAX_PDCH_GROUP: Maximum number of PDCH TS per cell ( can be anyfrom 1 to 8)

The operator can choose the maximum GPRS traffic capacity.

MAX_PDCH_HIGH_LOAD: Maximum number of PDCH TS per cell in case ofCircuit Switched traffic overload cell ( can be any from 1 to 8)

The operator can prioritise non-GPRS traffic versus GPRS traffic.

Those parameters allow the operator to prioritise Circuit-Switched (CS) traffic versusGPRS traffic in order for example to avoid QOS drop while introducing GPRS.

Also Quality parameters could be used as the number of MS that can share a samePDCH.

B6.2 Limitations:

1 TRX maximum per Cell is able to carry GPRS traffic (Up to 8 PDCH /cell)

CS-1 (9.05 Kbps) and CS-2 (13.4 Kbps) channel coding schemes.

A maximum of 32 mobiles can be in transfer simultaneously within a cell.

As GPRS and CS are using the same channels for Paging (PCH) and Assignment(AGCH) flows, one should take care of GPRS contribution in order to avoid anycongestion and especially for Combined signalling channels.

Up to 240 active PDCH per GPU

4.1.2 Radio channels type

The different timeslot configurations for the transceivers of a BTS are the same in releaseB5 and release B6.2. PDCH TS are used for the GPRS(see 4.1.1)


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The allocation of SDCCH/ CCCH is depending the call mix and the position compared tothe Location Area Border. (Example of Call mix 7.4 that has been used for thecalculation in 4.1.3, 4.1.4, 4.1.5)

Concerning TS content, several configurations are encountered, the most relevant are:

Traffic channels :

TCH

Signalling channels:

BCC = FCCH + SCH + BCCH+ CCCH

CBC = FCCH + SCH + BCCH+ CCCH+ SDCCH/4+ SACCH/4

SDC = SDCCH/8+ SACCH/8

Note: For cells used for SMS-CB, CBC or SDC signalling channels are replacedrespectively by CBH and SDH. This reconfiguration is impacting SDCCH capacity so oneshould avoid the reconfiguration on cells that have SDCCH overload problem.

The various radio channels configurations will be split up into the different call mixes butone has to keep in mind that there is no strict correlation between the geographicalmorpho-structure and the so called traffic mix.

In order to define the number of SDC channels, we will generally associate:

Rural configuration with low traffic and low SMS rate Urban configuration with high traffic and high SMS rate

Urban dense configuration for traffic peak (many call attempts)

4.1.3 Rural Configurations

The traffic density is low, therefore we consider configurations with maximum 2 TRX.

One TRX : 4 SDCCH, 7 TCH, 1 CCCH

TRX 1 CBC TCH TCH TCH TCH TCH TCH TCH

Two TRX : 8 SDCCH, 14 TCH, 1 CCCH

TRX 1 CBC SDC TCH TCH TCH TCH TCH TCH

TRX 2 TCH TCH TCH TCH TCH TCH TCH TCH


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As a general rule, SDC are rather allocated in the first TRX in order not to lose SDCCH incase of radio recovery.

4.1.4 Urban Configurations

For microcells with medium load (max 2 TRX), we have the same configurations as ruralconfigurations.

For a number of TRX between 3 and 12, Alcatel proposes:

Number of

TRX SDCCH TCH

3 16 214 24 28

5 24 36

6 32 43

7 32 51

8 40 58

9 40 66

10 48 73

11 48 81

12 56 88

This is standard configuration for restricting traffic mix and might be optimised (i.e. replacesome SDCCH by new TCH) depending on specific mixes.

Time slot split between signalling and traffic channels on the different TRX is:

TRX 1 BCC SDC TCH TCH TCH TCH TCH TCH


TRX 3 TCH SDC TCH TCH TCH TCH TCH TCH





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4.1.5 Urban Dense Configuration

If specific SDCCH congestion risk exists in the macrocell, a microcell linked to themacrocell is used.

The microcell helps to face a heavy load in the macrocell on traffic hotspot area.

One TRX microcell : 8 SDCCH, 6 TCH, 1 CCCH


Two TRX microcell in the same situation : 12 SDCCH, 14 TCH, 1 CCCH




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4.2 Traffic available

Thanks to the above-mentioned tables, one can compute the number of traffic channels ineach configuration. Given a quality criterion (generally 2% on the air interface due toallocation failures), we can compute the traffic required as shown in the following Erlang Btable:

Nb of TCH 1 2 3 4 5 6 7 8 9 10

Offered traffic(Erl) 0.02 0.22 0.60 1.09 1.66 2.28 2.93 3.63 4.35 5.08

Nb of TCH 11 12 13 14 15 16 17 18 19 20


Nb of TCH 21 22 23 24 25 26 27 28 29 30


Nb of TCH 31 32 33 34 35 36 37 38 39 40

Offered traffic(Erl) 22.83 23.72 24.63 25.53 26.44 27.34 28.25 29.17 30.08 31.00Nb of TCH 41 42 43 44 45 46 47 48 49 50


Nb of TCH 51 52 53 54 55 56 57 58 59 60


Nb of TCH 61 62 63 64 65 66 67 68 69 70


Nb of TCH 71 72 73 74 75 76 77 78 79 80


Nb of TCH 81 82 83 84 85 86 87 88 89 90


Traffic available (2% of blocking rate)

0

10

20

30

40

50

60

70

80

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

Nb of TRX

Erlang

Erl


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- Twin Wide Band Combiner Stage modules which is a wide band combiner on thedownlink path and a splitter on the uplink path

- TRX modules which embrace modulating and frequency hopping functions

- SUM board which ensures operation and maintenance functions and provides theclock to the BTS.

This modularity allows configurations such as:

Duplexer

TRX TRX

EVOLIUMTM

EVOLIUMTM

EVOLIUMTM

EVOLIUMTM

EVOLIUMTM

Duplexer

Combiner

TRXTRX TRXTRXTRX

Duplexer

Combiner

Combiner Combiner

TRX TRXTRXTRXTRX TRXTRX TRX

1 sector 2 TRX 1 sector 4 TRX 1 sector 8 TRX

INCORPORER.

5.1.3 Evolium Evolution BTS

This EVOLIUM Evolution is done in a two step approach available in B6.2 SMG29-1

-EVOLIUM Evolution Step 1 contains following features:

- Merging of ANx and ANy functionality in one new module, ANc; this integration

providing:

- a compactness which is used to build new configurations,

- an easiest maintenance policy (reducing the number of spares).

- Optimization of the SUM module, providing a future-proof board, which is

prepared to handle a third and fourth Abis link, or to integrate a GPS receiver or

similar additional equipment through baby-boards directly plugged on the SUM

board.


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- Integration of base-band part of micro-wave (IDU) in indoor and outdoor cabinet,

building a complete integrated solution; this choice simplifying the installation

and maintenance process, and reducing logistics costs.

- Introduction of new configurations, such as:

- 3x2 TRX configuration available in an Outdoor Mini cabinet, reducing the

purchasing price and optimizing the floor space of an often used

configuration in rural environment,

- 3x4 TRX configuration in an AC Indoor cabinet, which avoids the use of an

external power supply cabinet, allowing to save floor space and to reduce

acquisition, installation and maintenance costs of an often used

configuration in urban environment.

-EVOLIUM Evolution Step 2 contains following features:

- Introduction of a new TRX module with EDGE provision (8-PSK and GMSK

modulation schemes), to answer to the increasing demand for highest data flow

services.

- Improved baseband processing with enhanced antenna diversity algorithms to

improve the Alcatel network quality of service.

5.1.3.1 Overall architecture

The BTS architecture for the EVOLIUM Evolution is identical to that of all known A9100

configurations. It is based on a three level architecture, consisting of:

- Antenna coupling level

- Transceiver (TRX) level

- Base Station Control Function (BCF) level

The information flow between the Air interface and the Abis interface is presented in the figurebelow.


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Antenna

coupling level

TRX level

BCF level Station unit module

Abis interface

AbbreviationsBCF Base station Control Function

TRX Transceiver

Antenna network stage ANc

Air interface

Combiner stage (ANy)Combiner stage (ANy)

TRXTRX TRXTRX TRXTRX TRXTRXTRXTRX TRXTRX TRXTRX TRXTRX TRXTRX TRXTRX TRXTRX TRXTRX

Antenna network stage ANc

5.1.4 High power GSM 1800

High power GSM 1800 consists in using a specific TRX module for GSM 1800. This highpower TRX is a solution to provide enhanced coverage solutions. Duplexer and combinermodules are reused without any change.

5.1.5 Single antenna

All the single antenna configurations use the new antenna network module RFE Duplexerand Combiner Stage which is defined as half duplexer + half combiner in a single box. Itsarchitecture is:

5.1.6 Low losses

Low loss configurations are obtained by removing a Combiner stage and adding ifnecessary a Duplexer stage

5.1.7 TMA and REK solutions

The Tower Mounted Amplifier (TMA) is a low-noise amplifier that allows to compensatethe losses incurred by received signals.

The TMA solution can be used with any A9100 BTS configurations. TMA is specially

recommended for HighPower configurations with up to 2 TRX per sector.


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The Range Extension Kit (REK) is a two-way amplification box that allows to enhance theradio performance of the A9100 BTS configurations in terms of cell coverage (includingboth Booster and TMA functionality i.e Transmitted and Received signal amplification).

The REK solution is available only in GSM900 frequency band. Moreover, REK can not beassociated to A9100 configurations including Wideband combiners (ANy):

Configuration Number of sector Condition Preequipment

Yes/No

Minimum number

of TRXs per sector

Maximum number

of TRXs per sector

Standard 1 sector GSM900 No 1 2



Low-loss 1 sector GSM900 No 3 4

Others Others Not allowed Not allowed Not allowed Not allowed

5.1.8 Multiband configurations

5.1.8.1 Multiband BTS

That consists in using the GSM 900 and 1800 bands in different sectors of the BTS.

Multiband BTS configurations (900/1800).

5.1.8.2 Multiband cellThose configurations consist of having 900 and 1800 TRX in each sectors of the BTS(BCCH in GSM 900 only).

The following table shows BSS generation equipment versus PLMN radio band.

Multiband 900/1800Yes = GSM 900 GSM1800 GSM 1900

BTS Cells

G2 BSC

G1 BSC N.A N.A

G3 BTS 1

M4M BTS N.A

M1M BTS N.A N.A N.A N.A

M2M BTS N.A N.A N.A

G2 BTS N.A N.A

G1 MKII.BTS N.A N.A N.A N.A

1Restricted in SMG28


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Multi-band BTS: That consists in using the GSM 900 and 1800 bands in different sectors of theBTS. Multi-band BTS configurations (900/1800).

Multi-band cell: Those configurations consist of having 900 and 1800 TRX in each sector ofthe BTS

5.2 G2 BTS in B6.2

G2 BTS configurations are still unchanged, except M3M which is no more supported.

However, G2 BTS with FUCO are not supporting GPRS feature and G2 BTS with FUMOhave a restricted GPRS usage (CS-1 channel coding only: 9.05 Kbps).

G2 BTS extended cell is not more supported.

5.3 G1 BTS in B6.2

G1 BTS MK1 (HW1,HW2) have to be removed.

MK2 BTS are still authorised but replacement of FUCO module by DRFU is nescessaryfor GPRS support.

Rmk : All G1 BTS Compact have to be removed. They are not supported since B5.

5.4 BTS configurations summary

How to read this summary?

- choose the BTS type

- select the sector-TRX configuration: as regards the number of TRX, only themaximum configuration has been reported, e.g. 1x8 TRX configuration embraces allconfigurations from 1x1 to 1x8.

- choose the line corresponding to your specific options: single antenna, low losses,highpower, indoor AC feeding

NB: for each configuration, availability has to be checked with an Alcatel representative


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G2 BTSType Nb of sectors Nb of TRX GSM 900 GSM 1800 GSM 1900 Air combining

Optional AC

Power

6 ABIS LINKS

The Abis interface is standard ITU-T G.703 / G.704 interface. It is based on a framestructure. The frame length is 256 bits grouped in 32 timeslots numbered from 0 to 31.The rate of each timeslot is 64 kbit/s.

On the Abis interface, the important feature introduced available in release B.6.2 is thestatistical signalling submultiplexing 16K and 64K.

In B6.2, the Qmux can be suppressed and the supervision is done through OML ( 6.3)

Before presenting these aspects, available topologies on Abis interface will be reviewed.

Type CharacteristicsNb of

sectors

Nb of

TRX

GSM

900

MK2

MK2 Std 1 8 X

MK2 Std+DRFU 1 8 X

G1 BTS


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6.1 Abis network topology

For a functional point of view, two topologies are specified to physically connect the BTSto the BSC.

1- STAR topology: One PCM link connects only One BTS to BSC. It ismaintained awaiting shifting out from the field all G1 BTS.

The star topology will be migrated as a particular case of a chain with one BTS for aBSC G2.

2- Open Multi-drop topology CHAIN: One PCM link connects up to 15 BTS(Statistic multiplexing) in serial order and the PCM is not looped back to BSC by thelast BTS.

In chain topology, the BSC isconnected with Abis link to a BTS. Thisone is connected to a second BTS witha second Abis link, the second BTS isat its turn connected to a third one andso on.

B TS B T S B T S

Abi s l i nkC h a i n T o p o l o g y

3- Closed Multi-drop topology RING: One PCM link connects up to 7 BTS in serialorder and the PCM is looped back to BSC by the last BTS.

In ring or loop topology, the last BTSof a chain is connected back to theBSC. This topology offers somesecurity since traffic between any BTSand BSC is broadcast on the twopaths, selection is based on dedicatedService bits / bytes. (e.g. please seenext section).

BTS

BTS

BTS

Abis link

Ring / loop Topology

6.2 Medium of Abis network TransportThere are several means to transport Abis Over Networks:

1- Terrestrial link mean called PCM 2Mbits/s link (64 Kbits * 32 Time Slots = 2048Kbits/s).

2- Microwave link same capacity or higher.

3- Digital Cross-connect Network equipment, which concentrates 4, 16 or 64 PCM 2Mbitslink.

Hub Microwave equivalent to DCN


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6.3 Abis traffic

This table presents the three types of channels to be mapped onto the transmission links.

Channel type TS position Purpose

Q mux(O&Mtransmissionsupervision)

TS 0 (TS 0 usage)

Other TS except TS 0(TS0 transparency)

Used by the BSC to manage Remote

Transmission Network Elements.

Ring control used in ring topology only

Ring controlR bits Other TS except TS0 Supervision of Ring continuity

Synchronisation controls

S bits

Any TS

(except if G1 generation)Direction of clock synchronisation

BTS channels

TCH Other TS except TS0 End user traffic

OML Other TS except TS0 LAPD channel for BTS (1 OML per BTS)

RSL Other TS except TS0 LAPD channel for TRX (1 RSL per TRX)

The Mapping is defined by:

1. TS bearing the Qmux

2. The presence or not of Ring control channel.

3. Allocation Rules of PCM TS to the BTS with Multiplexed Channel Block motifs.

This table gives a quick view of timeslot budget depending on Qmux channel position:

Supervision By QMux By OML

TS0 Transparency Usage Transparency Usage

Open Chain MD 30 31 31 N.A

Closed LoopMD

29 30 29 N.A

Note 1:On transmission point of view, one must look carefully at one point :A BTS with 3 sectors with 4 TRX in each sector is in fact:

- 3 BTS of 4 TRX with G2 BTS which corresponds to 3 OML and 12 RSL.

- 1 BTS of 3x4 TRX with EvoliumTM

A9100 BTS which corresponds to 1 OML and 12RSL.


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6.4 Signalling submultiplexing Schemes

6.4.1 Presentation of concept

The signalling submultiplexing offers improvement in terms of required PCM time slots onthe Abis interface. This leads to substantial savings in terms of Abis interface trunks.

In B6.2, three types of signalling submultiplexing will be offered :

- 16K Static multiplexing: Up to 4 RSL of a BTS are multiplexed on the same Abistimeslot.

- 64K Statistical multiplexing: Up to 4 RSL and optionally the OML of a BTS aremultiplexed on the same Abis TS.

- 16K Statistical multiplexing: The RSL and optionally the OML of a BTS aremultiplexed in the first 2 bit of the TS reserved for TCH handling (the first one of the

two TS dedicated to handle the traffic of the TRX).Note : See constraints in paragraph 7.2.1.2

No Multiplexing16K Static

Multiplexing64K StatisticalMultiplexing

16K StatisticalMultiplexing

Number

Of FR TRX

TrafficChannelper TRX

SignallingTS*

(RSL/OML)

TotalSignalling

TS*Total

SignallingTS*

TotalSignalling

TS*Total

1 TRX 2 1/1 4 1/1 4 1/0 3 0/0 2

2 TRX 4 2/1 7 1/1 6 1/0 5 0/0 4

3 TRX 6 3/1 101/1

82/0

8 0/0 64 TRX 8 4/1 13 1/1 10 1/0 9 0/0 8

5 TRX 10 5/1 16 2/1 13 2/0 12 0/0 10

6 TRX 12 6/1 19 2/1 15 2/0 14 0/0 12

7 TRX 14 7/1 22 2/1 17 3/0 17 0/0 14

8 TRX 16 8/1 25 2/1 19 2/0 18 0/0 16

9 TRX 18 9/1 28 3/1 22 3/0 21 0/0 18

10 TRX 20 10/1 31 3/1 24 3/0 23 0/0 20

11 TRX 22 11/1 - 3/1 26 4/0 26 0/0 22

12 TRX 24 12/1 - 3/1 28 3/0 27 0/0 24

* Signalling TS are described as follow: RSL/OML

Note:. The activation of a signalling submultiplexing schemes is done by BTS. Theactivation by sector is only possible for 64k statistical multiplexing.


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6.4.3 64K statistical multiplexing

The Abis channels for this multiplexing scheme may be seen as a group of MCB

(Multiplexed Channel Block) : Three types of MCB have then been defined in accordanceto the number of TRX to be handled.

Name Nb of TRX Nb of Abis 64 kTS used

OML: RSL Compatibility

MCB 64/4 4 9 (0 or 1) :4 FR Only

MCB 64/2 2 5 (0 or 1):2 FR or DR

MCB 64/1 1 3 (0 or 1):1 FR or DR

MCB 64/1 1 3 (0 or 1):1 FR or DR

When several MCBs are used for a BTS, the OML is mapped on the MCB which has thelower SDCCH load.

6.4.3.1 Full Rate TRE

A BTS with N FR TRE configured with 64K statistical multiplexing requires:

(N/4) MCB 64/4

one MCB 64/1 when N mod 4 = 1 (BTS with 1, 5 or 9 TREs)

one MCB 64/2 when N mod 4 = 2 (BTS with 2, 6 or 10 TRES)

one MCB 64/1 and one MCB 64/2 when N mod 4 = 3 (BTS with 3, 7 or 11 TREs).This configuration is used instead of MCB 64/3 to allow a better usage of TCU

resources at the BSC. It consists of splitting the last 3 RSL into 2 Abis-TS. The 2fractions can be mapped on 2 different TCUs.

Number ofFR TRE per

BTS

list of physicalMCBs

Maximum SDCCH weightper MCB

1 64/1 24

2 64/2 32

3 64/2; 64/1 32;24

4 64/4 32

5 64/4; 64/1 32; 24

6 64/4; 64/2 32; 32

7 64/4; 64/2; 64/1 32;24;24

8 64/4; 64/4 32; 32

9 64/4; 64/4; 64/1 32; 32; 24

10 64/4; 64/4; 64/2 32; 32; 32

11 64/4; 64/4;

64/2; 64/1

32; 32;

32;24

12 64/4; 64/4; 64/4 32; 32; 32


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6.4.3.2 Dual Rate TRE

A BTS with N DR TRE configured with statistical multiplexing includes ((N-1)/2)+1 MCBsof which:

(N/2) MCB 64/2

(N mod 2) MCB 64/1

Dual rate attribute is now introduced per TRE and not anymore per BTS. As a result, onlythe TRXs using the DR mode must follow the rules concerning DR TRXs in particular thepossibility to connect 2 TRXs-DR per TCUC.

6.4.3.3 Limitations and requirements

G2 BSC and Evolium A9100/910 BTS.

6.4.4 16K statistical multiplexing

On the PCM link, two 64Kb/s timeslots are needed per TRE (128 Kb/s per TRE, 8 times16Kb/s).

Each RSL -which maybe statistically multiplexed with the OML- takes the place of the first16Kb/s sub-channel reserved for the associated TRE on the PCM link.

As for 64K statistical multiplexing, Abis transmission can be seen as a sequence of MCB16/1.

MCB 16/1

TS n0 Bit 1 Bit 2 Bit 3 Bit 4 Bit 5 Bit 6 Bit 7 Bit 8

N RSL FU1 + OML FU1 TCH 2 FU1 TCH 3 FU1 TCH 4

n+1 FU1 TCH 5 FU1 TCH 6 FU1 TCH 7 FU1 TCH 8

The OML is always multiplexed with the RSL with the highest RSL number of any BTSsector.

6.4.4.1 Limitations and requirements

G2 BSC and Evolium A9100/910 BTS.

Each TRX should carry a maximum of 8 SDCCH channels.

Not compatible with DR mode.

TS0 on Air Interface must not hold TCH channel (But a signalling channel:BCC,SDC)

Recommendation: with Abis multiplexing statistical 16k, BTS downloading at busy hourshould be avoided in order not to delay call set-up time


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6.5 Abis mapping rules

Installation of the new BSS software release 6.2 has no impact on the Abis TS mapping.

The control channels (Qmux, Sbits, R bits) as well as the BTS channels (TCH, RSL, OML)are not remapped as a consequence of software upgrade.

Signalling submultiplexing is compatible with all types of transmission mappings, starand closed catalogue excepted.

GPRS has no impact on Abis mapping because PDCH are dynamically allocated on thisinterface.

This part presents first some mapping techniques supported in previous softwareversions, star and closed catalogue mapping. Secondly, the free mapping is described.

The open decreasing mapping and full allocation mapping, defined in B.4, are now part offree mapping techniques.

6.5.1 Support of external cross-connect

When cross-connects are used on Abis it is needed to have different numbers for AbisTSs used by the BTS (Qmux bus, OML, RSL and TCHs) on BTS connector and on BIUAconnector.

This flexibility is supported by the introduction of TS mapping table between BTSconnectors and BIUA connectors.

This TS mapping table is introduced by the operator via the OMC-R and applied by the

BSC when a new BTS-BIE configuration is needed due to a modification of the Abis TSsallocation.

In order to keep the B6 principle of auto-allocation of TREs, this TS mapping table will beintroduced during the operation Create an Abis chain/ring. But to keep also a relativeflexibility on the TS allocation within the TS reserved for each branch connected to thecross-connect, the operator must be able to select also the TSs usable by each BTSduring the Create BTS operation.

It is also important to note that the OMC-R operator must be able to change at any timethe TS mapping table attached to one Abis chain/ring or to modify the TSs usable for eachBTS.


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BSC

BTS2

BTS3

BTS1

BTS 1 TS 2 to 4BTS 2 TS 11 to 15BTS 3 TS 21 to 24

BTS 3 TS 2 to 5

BTS 2 TS 2 to 6

Branch 1

Branch 3

Branch 2

Constraints of cross-connect usage on Abis

Cross-connect usage on Abis is supported only if the following rules are applied:Rule n 1 : One BTS uses (for itself and for the forwarded Abis link) only timeslots of aPCM, which comes from a single BIUA connector.

Rule n 2: If Qmux is used, the BTS needs to be connected to the Qmux TS. The otherBranch has to use OML if possible (Evolium BTS).

Note: AND and BROADCAST function on the Qmux timeslot are always needed in theintermediate cross-connect in order to respect rules n 2, if this function is not possible theQmux bus is not implemented and the downloading of the transmission settings isperformed via OML (if supported (Evolium BTS)) or locally.

6.5.2 Mapping techniques

Up to now, there are 4 techniques introduced during different releases:

1- Star Mapping: introduced before B4.

2- Closed Catalogue : Introduced before B4 (Appendix1)

3- Open Catalogue: Introduced in B4

4- Free Mapping: Introduced in B5: with Q1 TS fixed at TS0, TS1, option (TS16 orTS18).

5- Free Mapping in B6.2 : the Q1 can be slotted anywhere in TS from TS0 to TS31B5 mapping techniques are migrated but not exist anymore in B6.2, they are replaced byfree mapping

6.5.3 B5 BSC G1 Mapping

After B5-B6 migration, the BSCG1 is still running in B5, thus the Abis interface stay withthe following mapping.


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6.5.3.1 Star Mapping (Appendix1)

The star configuration is the configuration used in star topology.

It is configured in two modes: TSO usage: Qmux on TS0.

TS0 transparency: Qmux on TS 19.

The star configuration is the only one configuration supported by G1 transmissioninterface equipment named BIU2M, composed of one SMHW plus one or two SMBS.

Restriction: STAR mapping with TS0 Usage is forbidden with SMBI, SMFG, SUMP.

The Static Sub-multiplexing RSL 16Kb/s is not supported.

6.5.3.2 Closed Catalogue mapping (Appendix1)

Closed catalogue is used for chain or Ring topology in TS0 usage. Qmux and S bits usethe TS0. The allocation of TS for the BTS is fixed one for all. The advantage of this rule isthat the Add or delete BTS/TRE has no impact on other BTS on the same link.

RSL 16k sub-multiplexing is not compatible with closed catalogue.

6.5.3.3 B5 Free mapping

"Free mapping" means that the BTS channels can be mapped on any free PCM timeslot.

The assignment of the Abis TS can be performed automatically using the free mappingrule either for new Abis links or for modifications.

In Free mapping, the Time Slots of the Abis frame are allocated freely by CMA. The onlyrestriction is that the TCH of a TRE are always on 2 consecutive TS.

Five options are available:

Topology option

Option

S bits Qmux R bits

Chain Mapping TS1 OD1 - TS 1 - for new links/

from existing opendecreasing .

Ring Mapping TS18+RS OF1 TS 17 TS 18 TS 31 for new links/

from existing Fullallocation R1

TS16+RS OF2 TS 15 TS 16 TS 31 from existing Fullallocation R2

TS1+RS OF3 TS 17 TS 1 TS 2 For new links (Mix BIU2M,G1, G2, G3)

TS1+R OF4 TS 1 TS 1 TS 2 For new links (BIUMD, G2,

G3)


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7 G2 BSC CONFIGURATIONS

7.1 Overview

The G2 BSC consists in one switch and 3 main sub-units (TSU):

- Abis TSU which determines the connectivity with BTS

- Ater TSU which sets the capacity the BSC can handle

- common TSU

BIUA

TCUC

TCUC

TCUC

TCUC

TCUC

TCUC

TCUC

TCUC

AS

DTCC

DTCC

DTCC

DTCC

DTCC

DTCC

DTCC

AS

DTCC

CPRC CPRC CPRC CPRC CPRC CPRC CPRC CPRC

AS

6 xG.703AbisI/F

2 xG.703AtermuxedI/F

Abis TSU Ater TSU

Common Functions TSU

Group Switch8 Planes2 Stages

TSCA

TSL

ASMB

ASMB

Q1 bus

Broadcast bus

Since B5 release, 6 configurations of G2 BSC are offered:

Configuration Racks Abis TSU Ater TSU

1 1 1 2

2 1 4 3

3 2 6 5

4 2 9 6

5 3 11 8

6 3 14 9


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7.2 Abis TSU connectivity

7.2.1 Rules

7.2.1.1 Allocation of TSL link to TCUC

TSL is a LAPD link connecting the TCUC to the TSC (Transcoder Submultiplexer Controler).The TSC is in charge of the supervision of the transmission part of the BSS equipment. It pollsthe NE and collects the alarms indications. After correlation process it sent the list of the activealarms to OMC_R.

The TSL/TCU mapping is fixed.

TSL links G2 BSC BIUA number

(BSC-Adapt SBL nbr)

TCU number

TSL 1 (first rack) 1 1

TSL 2 (second rack) 6 41

TSL 3 (third rack) 11 81

The TSL when present uses one of the six LapD controllers of the G2 TCU.

7.2.1.2 Allocation of TRX and BTS to TCUC

Each TCUC can handle 6 signalling links (LAPD such as RSL, OML or TSL) which allows

excepting TSL which have been presented previously: 4 RSL+ 2 OML

3 RSL+ 3 OML

Each TCUC can handle 32 Traffic channels which allows:

4 Full Rate TRXs

2 Dual Rate TRXs

Each TCUC can handle either Full Rate or Dual Rate traffic.

Each TCUC can handle 32 SDCCH channels. However, in case of 16K SignallingMultiplexing (Static or statistical 16kbit/s) each TRX can carry 8 SDCCH channels

maximum. Each TCU can handle a maximum of 3 cells due to processing power to handle CCCH

signalling

In case of Signalling Multiplexing:

16K Static multiplexing: all RSLs of a given 64 kbit/s Abis time-slot must behandled by the same TCUC or by two adjacent TCU (TCU1 and 2, TCU 3and 4..).

Statistic Multiplexing: All RSL and OML multiplexed are processed on the same TCU.

Mix of the different signalling multiplexing and not multiplexed signalling on the same TCU isallowed for Full Rate.

Mix of none and statistical multiplexing 64 k is now allowed for Dual Rate.


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7.2.1.3 Allocation of TRX and BTS to TSU

all TRXs of all BTSs of a same Abis multidrop must be connected to a single Abis TSU

each Abis TSU can handle 6 Abis links which allows:

maximum 3 ring configuration (looped multidrop)

maximum 6 chain configuration (open multidrop or star configuration)

a maximum of 16 Dual Rate TRX assigned to a maximum of 16 BTS may be connected to asingle Abis TSU

each Abis TSU holds 8 TCUC

TRXs of one BTS cannot be split between two different Abis PCM, thus in two different AbisTSU.

Abis TSU may mix FR and DR cells

7.2.1.4 Maximum number of TRX

Configuration Full Rate TRX Dual Rate TRX

1 32 16

2 128 64

3 192 96

4 288 144

5 352 1766 3521 224

7.2.1.5 Maximum number of BTS/cells

Full rate mode Dual rate mode

Configuration Max nb ofBTS

Max nb of cells Max nb of BTS Max nb of cells

1 23 32 16 16

2 95 128 64 64

3 142 192 96 96

4 214 264 144 144

5 255 264 176 176

6 2551 264 224 224

1This is a software release limitation.


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7.2.2 G2-BSC Half Rate Flexibility

Currently GSM network operators see the HR as a way to extend the capacity of their network

without any additional hardware deployment (i.e. without any extra significant cost).

The gradual HR introduction is done by allowing the operator to define each individual TRE asFull Rate or Dual Rate (provided the BTS hardware is compatible). This allows to control the HRratio on a per cell basis. In addition a DR-preferred parameter is introduced at TRX level. Theneed to choose the speech coding rate per TRX comes from Telecom constraints; it allows inparticular to select DR-preferred for TRXs with a good radio quality.

The speech coding rate of a TRX requested by the OMC operator is a preference;

it can be changed by the system if no mapping is possible ( TRE and TCU may be of the

same type) it can also be changed if justified by the protection of a TRX (carrying BCCH or SDCCHs)

during a recovery

Nothing (or little) is changed to the TCU management :

FR TREs are mapped to a FR TCU which can support four of them

DR TREs are mapped to a DR TCU which can support two of them

The TCUs of a TSU are allocated, by the BSC, to support FR or DR TREs according to themapping algorithm.

As TREs are to be mapped on either FR or DR TCUs, this implies that the two types of TREsneed to be put in separate MCBs (i.e. their RSLs cannot be multiplexed together, which asks forat least two A-bis SIG TSs).

Warning : This feature does not provide help to the operator to deal with the fact that allowingHR calls in a cell will increase the signalling load and may ask for more SDCCH channels. Theoperator should configure a relatively higher number of SDCCH on DR TRXs and a relativelylower on FR TRXs. Since TCUs can either handle 2 DR TRXs or 4 FR TRXs, this leads tospreading more evenly the signaling load.

7.2.3 Recommendations

When using Signalling Multiplexing, if the detailed Abis topology is not known, then oneshould not connect more TRXs than 85% of the maximum connectivity.

When selecting among the different possible Abis TSU in order to connect a given BTS, onehas advantage to leave some spare capacity in all Abis TSUs so as to allow extensions inevery Abis TSU.


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7.3 Ater TSU capacity

This section enables to determine the traffic offered by the G2 BSC in the variousconfigurations.

7.3.1 Rules

7.3.1.1 Multiplexing on Ater link

Since B5, 4:1 multiplexing is available on the Ater interface which impacts the capacity of theG2 BSC. For more details about multiplexing constraints, refer to 10. Thus, we will hereafterdescribe the characteristics of Ater capacity according to each multiplexing scheme.

As regards equipment, one cannot mix G1 and G2 transcoding-submultiplexing equipment.

7.3.1.2 Number of channels and interfaces

Configuration A ITF Ater ITF CICs PCM nb

1 12 4 356 4

2 18 6 536 6

3 30 10 894 10

4 36 12 1074 12

5 48 16 1432 16

6 54 18 1612 18

1:3 mux

Configuration A ITF Ater ITF CICs PCM nb

1 16 4 454 4

2 24 6 686 6

3 40 10 1148 10

4 48 12 1380 12

5 64 16 1842 16

6 72 18 2074 18

1:4 Mux

7.3.1.3 SS7 links dimensioning

Exactly one channel is reserved for SS7 link on each Atermux link. Alcatel default dimensioningrule is to use all the SS7 links, thus leading to the following table with a call mix like 7.4.1

Configuration 1 2 3 4 5 6

SS7 links 4 6 10 12 16 16

Remark: with configuration 6 Atermux trunks 17 and 18 do not convey SS7 links; however, TS16 is left unused and does not convey any traffic channels.

With a modified call mix, speech holding time superior to 80 seconds. The rule is one SS7 link

for 2 PCM + 1 SS7 link. Which yields : for config 1 to 6, respectively 3, 4, 6,7, 9 and 10 SS7links.


The default dimensioning rules to be used on the Ater interface are:

0.1% of blocking rate

OR

80% of the maximum load which corresponds to 24 Erl/PCM

When using those maximum Erlang values, one should take into account a moderation factor tobe applied on busy hours traffic calculation.


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1:4 Mux (Erlang) 1:3 Mux (Erlang)

Configuration 0.1% blocking rate 24 Erl/PCM 0.1% blocking rate 24 Erl/PCM

1 160 160 160 160

2 627 576 483 432

3 1074 960 828 720

4 1300 1152 1002 864

5 1753 1536 1351 1152

6 1800 1728 1527 1296

When dimensioning a network, one must check that the maximum traffic generated by thedifferent BTSs does not exceed the maximum traffic handling capacity of the BSC to which theyare connected.

When subscriber density and traffic per subscriber are known, the traffic generated by the BTSsserving those subscribers can be immediately derived; but when only the number and size ofBTSs are known, the traffic must be assessed.

To do so, a first traditional approach is:

- to evaluate the maximum traffic generated by each cell (taking into account its numberof TRXs and applying the Erlang B law ),

- to sum all those traffics,- and then compare this sum to the maximum handling capacity of the BSC.

Optimized approach : use of the Moderation Factor

However, it has been noticed that the actual traffic incurred by the BSC is generally significantlylower than the theoretical traffic calculated as above (this theoretical calculation does notaccount for the fact that the maximum traffic is not reached simultaneously in each cell, or thatnot all the TRXs of a BTS or all the Traffic Channels of a TRX are fully used; see [8] for moredetails).

To account for this and avoid over-estimating the number of BSCs necessary for a givennetwork, the notion of Moderation Factor has been introduced: the Moderation Factor is definedas the ratio between the actual traffic incurred by the BSC at its busy hour and the theoreticaltraffic figure obtained by summing the maximum traffic generated by each connected cellaccording to the Erlang B rule. The value of the Moderation Factor can vary very significantlydepending on the network context; except for very dense urban areas, a maximum value of 0.8may already be used; significantly lower values may even be used in many cases as describedin document [10].

The recommended approach to check that the traffic generated by the BTSs does not exceed

the capacity of the BSC is then:


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- to evaluate the maximum traffic generated by each cell (taking into account its numberof TRXs and applying the Erlang B law ),

to sum all those traffics,

- to multiply this sum by the Moderation Factor

- and then compare the value obtained to the maximum handling capacity of the BSC.

(It must be noted that using the Moderation Factor is also recommended for the assessment ofthe number of A Interfaces and of Transcoders)

7.4 Processor load

7.4.1 Rules

The processor load depends on the amount of signalling events generated by the subscriberswith a given traffic. Alcatel commitments rely on a traffic mix, also called virtual call mixbecause its BHCA (busy hour call attempt) was brought to 1 by a rule of three in order tocompare different traffic mixes.

Alcatel warrants that, provided that none of the characteristics of the virtual call mix applied tothe G2 BSC exceed the value in the following table the BSC will function correctly.

Event Unit G2 BSC

Mean TCH duration S 50

Paging messages paging message per s 70

LU ratio LU per call attempt 3

Internal HO per call attempt 2

External HO per call attempt 1

MO SMS per call attempt 0.1

MT SMS per call attempt 0.4

IMSI attach ratio of IMSi attach per call attempts 0.5

IMSI detach ratio of IMSi detach per call attempts 0.5


If any of the characteristics of the required call mix exceed the above standard mix then,as long as other characteristics are relaxed it is very likely that the G2 BSC will be able toprocess the required traffic. However, in all such cases Alcatel must analyse therequirement to determine whether it is feasible.


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8 G1 BSC CONFIGURATIONS

8.1 Overview

With the G1 BSC, the TSUs are not taken into account in the definition of the standardconfigurations and the Abis submultiplexers (BIE) are individually configurable in separatetransmission cabinet. Thus G1 BSC can be represented as follow:

SWITCH

TCU

TCU

TCU

DTC

DTC

DTCCPRA

ATER

G1 BSC

ABISS

M

S

M

There are 2 families of G1 BSC:

- 2A types which exist in 5 configurations

- 2B types which exist in 4 configurations

2A Configuration Racks TCU A ITF 2B Configuration Racks TCU A ITF

1 1 8 6 1 1 12 6

2 1 20 6 2 1 28 8

3 2 32 9 3 2 44 9

4 2 44 12 4 2 60 15

5 2 52 15

8.2 Abis connectivity

8.2.1 Rules

8.2.1.1 Allocation of TRX

With G1 BSC, TCU rules become:

- 1 TCUA can handle

2 TRX with 2A configurations

1 TRX with 2B configurations


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- 1 TCUA can handle a maximum of 8 SDCCH

- half rate mode is not supported

2A Configuration Nb of TCUA Nb of TRX 2B Configuration Nb of TCUA Nb of TRX

1 8 16 1 12 12

2 20 40 2 28 28

3 32 60 3 44 44

4 44 60 4 60 60

5 52 60

NB: In case of 2A configurations, if one wants to connect an odd number of TRX to theBSC, one has to reserve the Abis TS corresponding to upper even number of TRX.

8.2.1.2 Allocation of BTS and cells

G1 BSC transmission constraints:

- each sector is considered as a BTS

- submultiplexing equipment must be inserted between G1 BSC and connected BTSs

- the maximum connectivity of the submultiplexing equipment is 24 PCMs

- signalling multiplexing is not supported

Maximum capacities of G1 BSC:

- a maximum of 40 BTSs can be connected

- a maximum of 40 cells can be connected

2A Configuration Nb of BTS/cell 2B Configuration Nb of BTS/cell

1 8 1 12

2 20 2 28

3 32 3 40

4 40 4 40

5 40

8.3 Ater capacity

8.3.1 Rules

8.3.1.1 Multiplexing on Ater link

With G1 BSC, one can only multiplex 3 Ater onto 1 Atermux link and multiplexingschemes are detailed in 10. However, one must not forget the following equipment rules:

- despite both G1 and G2 transcoding and submultiplexing equipment are available withthis release, they cannot be mixed.


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- submultiplexing is mandatory on Ater interface; however, existing sites which didntuse submultiplexing (between G1 BSC and G1 TC) are still supported.

8.3.1.2 Number of channels and interfaces

2A Configuration A ITF CICs PCM nb 2B Configuration A ITF CICs PCM nb

1 6 176 2 1 6 176 2

2 6 176 2 2 8 236 3

3 9 266 3 3 9 266 3

4 12 356 4 4 15 446 5

5 15 446 5

8.3.1.3 SS7 links dimensioning

On each A interface, one channel is reserved to allow SS7 link conveyance. Alcatelstrongly advises the customer to set one SS7 link for 3 plugged-in DTC in the BSCconfiguration. This leads to the following configurations:

2A Configuration SS7 links

1 2

2 2

3 3

4 4

5 5

2B Configuration SS7 links

1 2

2 3

3 3

4 5

The Alcatel filling rule for those SS7 links is to set 2 SS7 links on the first Atermux link, 2SS7 links on the second Atermux link, 1 SS7 link on the third Atermux link, and none onthe 2 remaining ones.


One has to check the following points:

- the number of A interface is compatible with the BSC configuration (see 8.3.1.2)

- the load computed with a quality criterion (0.1% of blocking rate or a percentage ofmaximum load) remains below the reference table:

2A Configuration Traffic capacity (Erl) 2B Configuration Traffic capacity (Erl)

1 80 1 60

2 140 2 140

3 210 3 210

4 280 4 320

5 320

8.4 Processors load

The characteristics of BSC configurations have been tested with the following contractual

call-mix:


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Event unit G1 BSC

Mean TCH duration s 90

Paging messages paging message per s 15LU ratio LU per call attempt 3

Internal HO per call attempt 1

External HO per call attempt 0.5

MO SMS per call attempt 0.1

MT SMS per call attempt 0.1

IMSI attach ratio of IMSi attach per call attempts 0.1

IMSI detach ratio of IMSi detach per call attempts 0.1

The above characteristics are relevant with a processor load remaining under 60% of its

maximum capacity.Remark: G1 BSC can handle the call-mix described in 7.4.1 with a capacity of 120 Erlang.

9 A935 MFS CONFIGURATIONS

9.1 Overview

Alcatel has developed the BSS part of GPRS with all dedicated hardware in a newequipment, named A935 Multi-BSS Fast packet Server (A935 MFS).

The figure below show the MFS position in the overall GSM network

BTSAbisAbis

Ater A

Gb

OMC-R

Ater

IMT

SGSN

BSC TC

MFS

(PCU)MSC

Gb


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9.2.2.4 OMC-R/MFS Connection

Rule 9 : If MFS on OMC-R site, a Hub is necessary to perform the connection theconnection of 2 cables (1 from each AS800) to only 1 cable towards the OMC.( Cisco

2500 can be also used)Rule 10 : If MFS on MSC site, and CISCO 4700 router alreadyinstalled, use of CISCO

Rule 11 : Other situation, connection via leased lines or X25.

9.3 A935 MFS Architecture

The A935 MFS is made from 1 to 2 telecom subracks, each one handling from 2 to 12GPU boards (Including one for redundancy). The granularity is one GPU board.

Each GPU board have 16 PCM interfaces. On each PCM, the timeslots to be processedcan be selected using the internal 64Kbps switch and in addition, any timeslot on onePCM can be transparently connected to any timeslot on its own or any other PCM.

GPU board

GPU board

GPU board

GPU board

GPU board

EthernetHu b

ServerServer

Ethernet link

Ethernet link (Redundancy)

2048 kbit/sPCM30

Interfaces

100 Mbit/s

Ethernet

Interfaces

Ethernet External Interfaces

9.4 A935 MFS Dimensioning

All the BSS connected to a single MFS must be managed by the same OMC-R (Managingalso this MFS).

There can be more than one MFS in a MSC area but one MFS shouldnt be shared byseveral MSCs unless they are collocated.


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A A935 MFS can handle up to 22 BSS (22 GPU boards + 2 for redundancy) and isconnected to one or more SGSN with a granularity at GPU level.

BSS with GPRS feature.

A BSS GPRS site configuration could be defined by combination:

(Release / BSC / TC / MFS/ BTS):

Release is B6.2.

BSC is G2.

TC is G2 or G1 generic.

BTS are Evolium, G2, G1.

9.4.1 GPU Dimensioning

Each GPU board can handle :

Up to 240 active PDCH (Packet Data Channels).

A single BSS can only be handled by a single GPU.

Up to 2880 Mobiles in packet transfer mode (Taking

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BSS Dimensioning Rules B6.2

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