49529487 abis-interface

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This is an internal document that applies up to the V12 BSS release.
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Abis Interface Engineering Guide
GSM
Reference : PE /IRC/APP/0079
Version : 01.08 / EN
Date : 12/04/99
Author : T. Bachelier
Documentalist : A.-M. Leberre
Approved by : M. Liem
Quality manager :
Ext. ref. :
Type : CEV
Product :
Cat : I
Status : A

Abis Interface Engineering Guide
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 edition
See 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 + rewriting
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 review
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 allows
more flexibility.
T. Bachelier
01.08 / EN 12/04/98 Modification after review. T. Bachelier

GSM
Reference : PE /IRC/APP/0079
Version : 01.08 / EN
Date : 12/04/99
ABIS INTERFACE ENGINEERING GUIDE

Abis Interface Engineering Guide Page 4
PE /IRC/APP/0079 01.08 / EN 12/04/99
TABLE OF CONTENTS
1 INTRODUCTION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
1.1 PURPOSE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
1.2 SCOPE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .8
2 RELATED DOCUMENTS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
2.1 APPLICABLE DOCUMENTS. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
2.2 REFERENCE DOCUMENTS. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
3 ABBREVIATIONS AND DEFINITIONS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
3.1 ABBREVIATIONS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
3.2 DEFINITION OF TERMS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
4 BTS CONFIGURATION. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .15
4.1 SITES AND CELL LAY-OUT . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
4.2 OFFERED TRAFFIC ASSESSMENT . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
4.3 RADIO INTERFACE DIMENSIONING . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
4.3.1 TCH. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
4.3.2 SDCCH . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16
4.3.3 BCCH . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16
4.4 CELL DIMENSIONING . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
4.4.1 Cell types . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
4.4.2 BTS configuration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
4.5 LOOK-UP TABLES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18
5 BTS DIMENSIONING . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20
5.1 SIGNALLING . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20
5.1.1 LAPD channel . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20
5.1.2 LAPD dimensioning. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .21
5.2 PCM. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26
5.2.1 Abis TS dimensioning . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26
5.2.2 PCM configuration rules . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26
5.3 DCC & DSC DIMENSIONING . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29
5.4 LOOK-UP TABLES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30
6 ABIS ARCHITECTURE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33
6.1 DROP&INSERT CONFIGURATIONS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33
6.1.1 Possible configurations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33
6.1.2 TEI issues . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .34

PE /IRC/APP/0079 01.08 / EN 12/04/99
TABLE OF CONTENTS
6.1.3 DTI/PCMI issues . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35
6.1.4 RadioSiteMask configuration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37
6.1.5 RadioSiteMask Extension strategy. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40
6.1.6 Additinal feature of TDMA/Abis mapping configuration for V11 . . . . . . . 42
6.2 HUBS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 43
6.2.1 Cross-connect . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 43
6.2.2 Switch. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 44
7 TRANSMISSION MEDIUM . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 46
7.1 CLOCK . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 46
7.2 TRANSMISSION QUALITY REQUIREMENTS . . . . . . . . . . . . . . . . . . . . . . . . . 47
7.3 CSU. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 49
7.4 HDSL. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 49
7.4.1 Introduction. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 49
7.4.2 HDSL issues. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 50
7.4.3 HDSL modems . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 50
7.5 MICROWAVES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 51
7.5.1 Microwave design Guidelines. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 51
7.5.2 Microwave Quality requirements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 53
7.5.3 Microwave configurations. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 54
7.5.4 Microwave equipment redundancy. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 56
8 BSC DIMENSIONING . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 58
8.1 BSC TYPE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 58
8.2 SICD/SICD8V BOARDS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 59
8.2.1 Limitation rules . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 59
8.2.2 Parenting rules . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 59
8.2.3 Look-up tables . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 60
8.3 BSCB AND TSCB BOARDS. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 60
8.4 DDTI BOARDS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 62
9 APPENDIX . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 63

PE /IRC/APP/0079 01.08 / EN 12/04/99
LIST OF TABLES
Table 1: BTS configuration limitations .............................................................................. 17
Table 2: Traffic for a given number of TRXs in a standard cell ........................................ 18
Table 3: Traffic for a given number of TRXs in an extended cell...................................... 18
Table 4: PCM configuration for S333 (TEI 0) with 1 PCM............................................... 26
Table 5: PCM configuration for S333 (TEI 0) with 2 PCMs ............................................. 27
Table 7: Internal E1 to external T1 conversion .................................................................. 28
Table 8: LAPD/DCC configuration.................................................................................... 29
Table 9: Omnisectorial BTS ............................................................................................... 30
Table 10: Bisectorial BTS................................................................................................... 30
Table 11: Tri and hexasectorial BTS.................................................................................. 31
Table 13: PCM E1 RadioSiteMask..................................................................................... 38
Table 14: PCM T1 RadioSiteMask..................................................................................... 38
Table 15: PCM E1 RadioSiteMask..................................................................................... 39
Table 16: PCM T1 RadioSiteMask..................................................................................... 39
Table 17: RadioSiteMask (first strategy)............................................................................ 41
Table 18: RadioSiteMask (second strategy)....................................................................... 41
Table 19: RadioSiteMask (Third strategy) ......................................................................... 42
Table 20: RadioSiteMask configuration with crossconnect ............................................... 44
Table 21: Timing requirements........................................................................................... 46
Table 22: Product range...................................................................................................... 58
Table 23: SICD limitations................................................................................................. 60
Table 24: Maximum number of sites per BSC ................................................................... 61
Table 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 ........................................... 33
Figure 2: Loop Drop&Insert configuration ....................................................................... 34
Figure 3: Hub&Spoke configuration. ................................................................................. 34
Figure 4: PCMI configurations for drop&insert................................................................. 35
Figure 5: D&I in loop without board redundancy: 1G versus 2G ...................................... 36
Figure 6: Drop & Insert example........................................................................................ 38
Figure 7: Hub&Spoke example .......................................................................................... 39
Figure 8: Example............................................................................................................... 40
Figure 9: Cross-connect configuration ............................................................................... 43
Figure 10: Crossconnect configuration............................................................................... 43
Figure 11: Architectuire with Switch ................................................................................. 44
Figure 12: HDSL solution................................................................................................... 49
Figure 13: Microwave solution........................................................................................... 51
Figure 14: Reference communication of ITU..................................................................... 53
Figure 15: Performance objectives: .................................................................................... 53
Figure 16: Chain Drop&Insert with microwaves ............................................................... 54
Figure 17: Loop Drop&Insert with microwaves................................................................. 54
Figure 18: Hub and Spoke with microwaves...................................................................... 55
Figure 19: Abis configuration with microwaves on BSC side ........................................... 55
Figure 20: Typical non-protected and protected microwave equipment architecture ........ 56
Figure 21: Dimensioning the Abis interface with LAPD concentration ............................ 61
Figure 22: Example of complex configuration................................................................... 63

Abis Interface Engineering Guide Page 8/64
PE /IRC/APP/0079 01.08 / EN 12/04/99
1 INTRODUCTION
1.1 PURPOSE
The purpose of this document is to give Abis interface engineering guidelines for the
NORTEL 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 Application
Engineers involved in GSM network Engineering within NORTEL GSM Networks
and 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 V11
PE/SYS/DPL/0089 V01.02/EN P. Vincent
[A02] Dimensioning the Abis interface
PE/SYS/DD/0070 V6.02/EN B. Couaillet
[A03] Transmission Network Recommendations
2.2 REFERENCE DOCUMENTS
[R01] V8 Engineering Changes
PE/IRC/APP/00030 V1.06/EN L. Jullien
[R02] V9 Engineering Changes
PE/IRC/APP/00048 V1.06/EN T. Bachelier
[R03] V10 Feature Engineering Information
PE/IRC/APP/00068 V1.08/EN S. Luong
[R04] V11 Feature Engineering Information
PE/IRC/APP/00072 V1.06/EN T. Bachelier
[R05] S8000 Outdoor BTS Engineering Information
PE/IRC/APP/00033 V4.02/EN Y. Maurin
[R06] S8000 Indoor BTS Engineering Information
PE/IRC/APP/00055 V4.02/EN Y. Maurin
[R07] S2000H BTS Engineering Information
PE/IRC/APP/00052 V3.04/EN M. N. Boursin
[R08] S2000L BTS Engineering Information
PE/IRC/APP/00053 V3.04/EN M. N. Boursin
[R09] BSC/TCU Engineering Information
PE/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 Guide
PE/IRC/APP/00037 V3.01/EN WGAl-WGSys
[R12] Defence mechanisms on PCM faults

PE /IRC/APP/0079 01.08 / EN 12/04/99
[R13] UIT-T Recommendations
G732 Characteristics of primary PCM multiplex equipment operating at 2048 kbit/s.
G811 Timing requirements at the output of primary reference clocks suitable for ple-
siochronous operation of international digital links.
G733 Characteristics of primary PCM multiplex equipment operating at 1544 kbit/s.
The control of jitter and wander within digital networks which are based on the
2048 kb/s hierarchy.
The control of jitter and wander within digital networks which are based on the
1544 kb/s hierarchy.
[R18] CT5100 Specification for Backhaul Optimization
PE/SPC/DD/00xx V1.01/EN A. Chevalier
[R19] GSM Transmission Engineering Guide
PE/IRC/APP/0086 V1.01/EN B. Pariseau
[R20] Nortel BSS performances
PE/BSS/DJD/0456 V1.01/EN A. Montès
[R21] HDSL modem layer1 qualification
PE/BTS/DJD/0962 V10.01/EN B. Corn
[R22] BSCB Eng’g Information: Load Monitoring and Optimization
PE/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 Function
BDA Application Database
BER Bit Error Rate
BPUG BSS Parameters User Guide
BSC Base Station Controller
BSS Base Station SubSystem
BTS Base Transceiver Station
CCCH Common Control Channel
CS Coupling System
CSU Channel Service Unit
DCC Data Channel Concentrator (BTS 1G)
DSC Data Signalling Concentrator (BTS 2G)
DCU Dual Channel Unit
DIU Digital Interface Unit
DM Degraded Minutes
DRX Driver + Receiver + Frame Processor
DTI Digital Trunk Interface
ES Errored Seconds
FEI Feature Engineering Information (document)
GSM Global System for Mobile communications
HDSL High bit rate Digital Subscriber Line
HG High grade
HLR Home Location Register
HO Handover
H/W Hardware
LA Location Area
LAPD Link Access Protocol on D channel
LG Local Grade
LOS Line Of Sight
L1M Layer 1 Measurements
MG Medium Grade
MS Mobile Station
NMC Nortel Matra Cellular
NMC Network Management Center
NSS Network Sub-System
O&M Operation and Maintenance
OMC Operation and Maintenance Center
OMC-R Operation and Maintenance Center-Radio
OMN Operation and Maintenance Network

PE /IRC/APP/0079 01.08 / EN 12/04/99
PA Power Amplifier
PBGT Power Budget
PCH Paging Channel
PCM Pulse Code Modulation
PCMI PCM Interface
PEI Product Engineering Information (document)
QOS Quality of Service
RFU Radio Frequency Unit
RV Rendez Vous
SES Severely Errored Seconds
SMS-CB Short Message Service - Cell Broadcast
SPCMI Small PCM Interface
TBC To Be Completed
TBD To Be Defined
TCH Traffic ChHannel
TCU Transcoder Unit
TEI Terminal Equipment Identifier
TMG Traffic Management
TRX Transmission-Reception subsystem of the BTS
TS 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 the
usable signal over the interferences level.
DRX:
The DRX is a part of the "2G" BTS system architecture. The first product that
supports 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 signal
processing (transmission and reception) called DRX, and one dedicated to the power
transmission, called PA.
Rendez Vous time slot:
This is the time slot of the Abis interface PCM link that carries the primary LAPD of
the BTS site. It has a fixed predefined position on the PCM (BTS side) because it is
the time slot used by BSC and the BTS to establish their first dialogue after a
scanning procedure.
Soft Blocking:
Procedure by which a TRX or a cell can be put out of service (i.e. blocked) without
interrupting 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 dimensioning
of the Abis interface. This part is performed by the Cellular planning in conjunction
with 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. There
are two different ways of working depending on the project context.
vIf the customer defines the site locations, then Nortel must define the predicted
coverage area.
vIf the customer does not define the site locations, Nortel assumes additional
activities for the site acquisition process follow-up such as along the site
acquisitions iterations, provision of optimal theoretical site location, site selection
rules, 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 subscriber
behaviour. The behaviour of subscribers includes the distribution of GSM
subscribers within the population, call profile, and mobility parameters. The offered
traffic 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 fixed
blocking rate applied to the assessed offered traffic. The assumption of NORTEL is
a blocking rate of 2% for traffic or data on the radio interface. One TCH channel is
carried 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 depends
on a large number of parameters:
• Mobility profile,
• Strategy used: For example, if most of the SDCCH requests are for call and
not 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 channels
are needed according to this strategy (Note that the Location Update will be
also supported by a TCH signalling). This strategy is only applicable to few
particular 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 number
of Location updates could be quite important. So, the number of SDCCHs
must 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 which
can strongly impact the SDCCH dimensioning.
Nevertheless, if we take only into account the NORTEL standard traffic model, the
number of required SDCCH can be easily determined.
The NORTEL standard traffic model indicates that 28 Erlangs of signalling traffic is
required for 100 Erlangs of speech or data traffic. After determination of the signalling
traffic, 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 SDCCH
channels 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 beacon
frequency.
In the case of one TRX per cell, BCCH can combined with one SDCCH/4 (4 SDCCH
channels) in order to have 7 TCH instead of 6. This configuration can be applied
under certain conditions such as the LA size. Actually, if the size of the LA is too
large, a great amount of paging will be generated and the PCH (which is limited in
this 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 SDCCH
channels.

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 different
kinds of cell: standard and extended cell. Extended cell allows bigger propagation
delay. The coverage of an extended cell could be bigger than the one of a standard
cell (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 which
manages 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 O16
configuration 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

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4.5 LOOK-UP TABLES
The following look-up tables give the offered traffic for a given number of TRXs with
the NORTEL standard call profile (blocking rate of 2%). When the offered traffic is
assessed, these look-up tables give a first assessment about the number of needed
TRX. After this first assessment, some deeper dimensioning can be performed
according 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 1
3 14.0 4.7 21 2 1
4 21.0 5.3 29 2 1
5 27.3 5.4 36 3 1
6 34.7 5.8 44 3 1
7 42.1 6.0 52 3 1
8 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 1
3 5.1 1.70 10 1 1
4 8.2 2.05 14 1 1
5 11.5 2.30 18 1 1
6 14.0 2.33 21 2 1
7 17.5 2.50 25 2 1
8 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 the
Operation and Maintenance, concerns all the component parts (BCF, TRX, Coupling
system, Power Amplifier ...). The second one, related to the traffic management, is
destined 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 the
same LAPD channel. A distinction is made between the BCF signalling and the cell
signalling.
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 BSC
limitations. At BTS side, the hardware and software limitations are related to the BTS
type. At BSC side, two main limitations can occur: connectivity (maximum number of
LAPD ports) and real time processing capability.
In fact two different strategies can be chosen by the operator to drive the LAPD
dimensioning:
• 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 the
BSC 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 such
configuration.
• 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 load
on the different boards in order to avoid an overloab on one board.
Of course, these two opposite strategies must fulfilled the BTS constraints. Each
type 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 time
processing. The BSC connectivity and the parenting rules at the BSC side will be
seen 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 account
because they always need one single LAPD channel. In fact, four different BTS have
been 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 a
single LAPD channel. But, for the sake of the BSC boards (refer to the following
section: BSC limitations in terms of real time processing), one LAPD per cell can
be defined.
S8000 BCF up to V11:
The maximum configuration is S888 and S444_444, S555_333, S666_222 for
dualband 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 a
single LAPD channel. But, for the sake of the BSC boards (refer to the following
section: BSC limitations in terms of real time processing), one LAPD per cell can
be defined.
v For dualband configurations (hexasectorial applications) Sxyz_x’y’z’, the rules
are 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 SICD
ports 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 multisectorial
site 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 rules
are 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.

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S8000 CBCF
The maximum configurations are O16 for omnisectorial site , S161616 for
multisectorial 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, 6
TRxs 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 signalling
interface between the BSC, the TCU, and the BTS. The SICD4 board (not the
SICD8V) can be the bottleneck of the BSC. Several BSC outages in the past were
due to an overload on the SICD4 card. The overload was either generated by high
Handovers, Paging and Location Update rates or by particulary high voice traffic
demands on certain sites (e.g. heavy load sites).
An overload mechanism has been introduced on the SICD board. But if this overload
mechanism is triggered, it will penalize the traffic (Q.O.S.) on all sites associated with
the SICD.
Therefore, it is really important to split the load on the different SICDs in order to
avoid 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 the
load on the available SICD boards. This implies that additional DCC/DSC cards may
be required on the BTS and that additional timeslots on the Abis interface are also
necessary. Please refer to the concerned BTS Product Engineering Information.
But it could make sense not applying these engineering rules if the forecast site traffic
is low, typically in rural area.
Note 1:
These engineering rules are applicable in a normal non-congested cell. They
cannot 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 refer
to section 8 (BSC dimensioning).
F One LAPD channel must be associated to one cell in high traffic zone (urban
zone) for the sake of the SICD for the BSC 6000.

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5.2 PCM
5.2.1 ABIS TS DIMENSIONING
On the Abis interface, two consecutive TS are used per TDMA and one TS per
LAPD.
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 further
information, 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 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)
vThe TS associated to TRX are mapped by two on two consecutive TS. The
convention is to use the higher TS of a PCM first, and then continue toward the
lower.
vThe secondary LAPD channels will be mapped on the free TS following the Traffic
TS.
vWhen several PCM link the BTS to the BSC, the traffic TS are equally shared on
those PCM.
SP : Signalling Link TS (Primary LAPD) T : Traffic TS
SS : 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

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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 forbidden
for T1. The association between the Abis TS on the BTS side and the possible TEI
number 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. The
convention is to use the higher TS of a PCM first, and then continue toward the
lower.
vThe secondary LAPD channels will be mapped on the free TS following the Traffic
TS.
those 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 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

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Explanations:
For T1 PCM, the SPCMI/PCMI/DTI converts internal PCMs (still in E1: 32 TS) to
external 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 but
applies to internal PCM. So, if the TEI was configured to value 3, the used TS would
be 4 and the BTS would still remain impossible to reach.
Therefore, TEIs number 3, 7, 11, 15 cannot be used for T1. The association between
the 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 relevant
for S4000 and S8000 BCF.
DCC/DSC concentrates LAPD signalling links onto a single one from the DRX and
the 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 the
number of cells and depending on the number of signalling concentrated links.
Note1: Certain configurations listed in the above table can only be achieved with
dualband configurations.
Note2: If, at a given time, the number of available DCC/DSC runs under the threshold
given in the table above, the whole site may be definitively lost (until the right number
of DCC/DSC becomes available again). Therefore, it is strongly recommended to
have 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 LAPD
dimensioning (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 urban
environment, SICD or SICD8V board, high mobility).
These tables could be useful for a first high level assessment, but not for an accurate
design of the network.
Moreover, some specific cases occur. For example, the S22 configuration can be
performed with the S2000H BTS. In this case the real configuration is 2 O2 BTS (not
synchronnized) colocated on the same site and linked in a Drop and Insert
configuration. Two LAPD channels are required to handle the 2 BCF signalling and
8 TS to handle the traffic of the four TDMA. Therefore, the number of required TS is
10 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 PCM
Erlang 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+1
O2 8.2 14 2.3 6 4 1 5 1 5 1 1+1
O3 14.0 21 5.1 10 6 1 7 1 7 1 1+1
O4 21.0 29 8.2 14 8 1 9 1 9 1 1+1
O5 27.3 36 11.5 18 10 1 11 1 11 1 1+1
O6 34.7 44 14.0 21 12 1 13 1 13 1 1+1
O7 42.1 52 17.5 25 14 1 15 1 15 1 1+1
O8 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+1
S22 16.4 28 4.56 12 8 1 9 1 9 1 1+1
S33 28 42 10.16 20 12 1 13 1 13 1 1+1
S44 42 58 16.4 28 16 1 17 1 17 1 1+1
S55 54.6 72 23 36 20 2 22 1 22 1 2+1
S66 69.4 88 28 42 24 2 26 1 14*2 2 2+1
S77 84.2 104 35 50 28 2 30 1 16*2 2 2+1
S88 97.4 118 42 58 32 2 18*2 2 18*2 2 2+1

PE /IRC/APP/0079 01.08 / EN 12/04/99
Table 11: Tri and hexasectorial BTS
S111 8.79 21 1.8 9 6 1 7 1 7 1 1+1
S222 24.6 42 6.8 18 12 1 13 1 13 1 1+1
S333 42.0 63 15.2 30 18 3 21 1 21 1 3+1
S444 63.0 87 24.6 42 24 3 27 1 15*2 2 3+1
S555 81.9 108 34,5 54 30 3 19*2 2 19*2 2 3+1
S666 104.1 132 42.0 63 36 3 21*2 2 21*2 2 3+1
S777 126.3 156 52,5 75 42 3 25*2 2 17*3 3 3+1
S888 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+1
S222222 49.2 84 13.7 36 24 6 18*2 2 18*2 2 3+1
S333333 84.0 126 30.5 60 36 6 24*2 2 24*2 2 3+1
S444444 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 these
different configurations.
Figure 1: Star, Drop&Insert and Hub&Spoke Configurations
The loop and chain Drop&Insert configurations are guaranteed for up to 6 BTSs. The
theorical limitation is 10 O1 BTSs on 1 E1 and 8 O1 BTSs on 1 T1, but R&D tests
and guarantees up to 6 BTSs.
Star
BSC
BTS
Loop D&I
BSC
BTS
BTS
BTS
Chain D&I
BSC
BTS
BTS
BTS
BTS
BTS
PCM
Redundant 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 each
BTS must be in an ascending sequence. The rule for the chain configuration is
x<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 no
constraint between w and the couple y,z (w and y can be equal). Note that the
Hub&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.

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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 the
interface of 1 PCM digital trunks. PCMI board handles the interface of 2 PCM digital
trunks. The following table presents the mapping between PCM ports and PCMI/DTI
boards.
The PCM links connecting the BSC to BTS must be arranged for synchronization
reasons. A PCM crossing a BTS enters via an even PCM port and leaves via an odd
PCM port. For the loop configuration, the opposite path can be set up.
The following figure shows some different Drop&Insert configurations with or without
PCMI 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
PCMI0
0
1
BTS
PCMI0
0
1
BTS
PCMI0
D&I in chain without redundancy D&I in loop without board redundancy
BSC
0
1
BTS
PCMI0
0
1
BTS
PCMI0
0
1
BTS
PCMI0
BSC
0
1
BTS
PCMI0
0
1
PCMI1
0
1
BTS
PCMI0
0
1
PCMI1
0
1
BTS
PCMI0
0
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 DTI
failure occurs, only one PCM will be lost and the opposite path will be activated. For
2G 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. The
PCMI 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 are
some impacts on redundancy, and then on reliability.
D&I in loop without board redundancy
BSC
0
1
BTS A
PCMI0
0
1
BTS B
PCMI0
0
1
BTS C
PCMI0
BSC BTS D
DTI0
BTS E BTS F
DTI1
DTI0 DTI0
DTI1 DTI1

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6.1.4 RADIOSITEMASK CONFIGURATION
Rules
For each site, a parameter called RadioSiteMask is configured in order to define
which 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 use
first the higher TS of a PCM and then continue toward the lower one. The
secondary LAPD follows the same rules as the traffic TS.
those PCM.
Some engineering rules define the value of the RadioSiteMask (total number of
timeslots set to 1):
For 1 PCM connected: (Nb LAPD - 1) + Nb TRX *2
For 2 PCM connected: (Nb LAPD - 1) + Ent[(Nb TRX + 1)/2] * 2
For 3 PCM connected: (Nb LAPD - 1) + Ent[(Nb TRX + 2)/3] * 2
For 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 between
TS0 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 are
linked 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 ascending
sequence.
The traffic of the BTS A is equally shared between the 2 PCMs. The secondary
LAPD follow the TS supporting the traffic. The primary LAPD is not included in the
radioSiteMask.
The BSC is a BSC6000, then 3 LAPD channels are defined for the site B in order to
be able to split the load on the different SICDs.
Ta Traffic Ts site A Pa Primary LAPD site A
Tb Traffic Ts site B Pb Primary LAPD site B
Sa Secondary LAPD site A
Sb 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 S222
PCM1
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 omnisectorial
BTSs 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 of
the 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 dimensioning
the RadioSiteMask. It will make the network roll-out easier.
The radioSiteMask parameter is a class 2 parameter located in the btsSiteManager
Q3 object. It means that this parameter can only be set when the object is locked and
the parent bsc object is unlocked. Therefore, the modification of the radioSiteMask
will involve interruption of service.
Moreover, forecasting the future extension will avoid some complex RadioSiteMask
configurations that are difficult to manage.
Different configuration strategies can be applied according to the knowledge of the
extension 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 allows
extensions without requiring the reconfiguration of the RadioSiteMask (no
interruption of service).
Figure 8: Example
The site A is composed of 6 DRXs in a cabinet. One cabinet can contain up to 8
DRXs. Therefore, it could make sense to foresee the introduction of the 2 other
possible DRXs. It would facilitate their introduction and avoid any interruption of
service 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 A
Tb Traffic TS site B
Pa Primary LAPD site A
Pb Primary LAPD site B
Of course, if Site A is composed of three radio cabinets, it does not make sense to
dimension 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 a
D&I configuration.
In such case, the RadioSiteMask can be defined as indicated in Table 18.
Ta Traffic TS site A
Tb Traffic TS site B
This configuration allows to easily increase capacity in the both site. The introduction
of additional DRX in a site will not perturb the other one, only one RadioSiteMask is
impacted. 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, because
the 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 also
possible to introduce additional DRXs without interruption of service for the second
site.
Ta Traffic TS site A Pa Primary LAPD site A
Tb Traffic TS site B Pb Primary LAPD site B
The drawback is that some RadioSiteMask can be quite complex and it will become
more 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 for
a 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 TS
reconfigurations and then to lose less traffic channels. Moreover it could facilitate the
introduction of new DRXs.
The drawback is that the evolution of the network could be more difficult (for
example, adding a BTS in drop&insert). There is a trade-off between quality of
service 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 allows
the simulation of a Drop&Insert function from the BSC point of view, without using
the 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 same
configuration (Star with a TEI = 0). For the BSC, the 3 sites are in drop and insert so
the drop and insert rules must be respected on the BSC side. The choice of the TS
for the signalisation must be done in accordance with the crossconnect
configuration.
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 the
crossconnect. This rule does not concern the primary signalling TS which has a fixed
position on the BTS side (TEIBCF+1).
Ta Traffic Ts site A
Tb Traffic Ts site B
Tc Traffic Ts site C
Pc Primary LAPD site CSwitch
6.2.2 SWITCH
Hubs can act as switch for redundancy purpose. The main advantage of this
architecture is that in case of PCM1 failure, the hub1 is able to switch on the
redundant 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 and
especially 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 precision
timing reference for the radio interface.
Long-term accuracy recommended for PCM E1 (2,048 MHz) and PCM T1 (1,544
MHz):
| ∆f/f | = 10 -9 or 0,001 ppm
This characteristic assures a good transmission quality for BTS frequencies allowing
the mobile connections and avoiding the disturbance of the adjacent frequencies.
Note: it is not necessary that all GSM sub-systems are synchronized with the same
clock, 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 determined
by 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 Errored
Seconds (ES if at least an error occurs for 1 second). For example, if the signal is
lost 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 Errored
Seconds), 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 is
interrupted for more than this timer, the BSC will try to find another PCM to
reestablish the contact. When the contact is reestablished, the BSC will lead in the
BTS 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 real
failure, and fast alarm reporting, and however tolerates short transient link outages
often 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 be
redownloaded and reconfigured when the link is up again. In case of DRX (S8000 or
S2000H/L) or AMNU/DCU4, the download procedure is reduced. In fact, the
software is not downloaded, but only checked.
The reconfiguration and reboot time depend on the BTS configuration. This kind of
information 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 the
communications.
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 BTS
which 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 the
operator and the BCF subrack. Its purpose is to test and recalibrate the incoming and
outgoing signal and ensure that it meets the recommendations. The equipment
includes a set of alarms displayed on the CSU front panel. Any alarm condition (or
power failure) releases a single pole alarm relay connected to the user alarms of the
BTS.
Three types of CSU equipment can be ordered: CSU T-serv II, CSU T-smart, and
CSU MPATH. The MPATH CSU offers additional features (such as SNMP
management) 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 over
ordinary twisted pairs. This technology becomes more and more popular, as a cheap
solution to provide PCM links to remote locations. This applies generally to the Abis
link, including Drop&Insert configurations.
Figure 12: HDSL solution
For short distances (up to 1.5 Km), only one wires twisted pair is needed. Two wires
twisted pairs are required for longer distance (up to 4 Km). The distances depend on
the modems and on the quality of the twisted pair wires. Therefore the values given
above 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 one
is on the BTS side. The consequence is that any short link drop or click disturbancy
leads to long link unstability. Depending on the modem, 1 second interruption may
translate up to 15 seconds.
The timer that triggers a defense BSS mechanism is set to 5 seconds (refer to
section 7.2 ). This value may no longer be the right trade-off between fast recovery
and 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 link
stability (but QOS impact). This specific parameter setting of the BSS defense
mechanism is not mandatory. Some HDSL modems work properly with the default
configuration.
Note that the timer value applies to all PCM links of the BSC and not only to the HDSL
links.
7.4.3 HDSL MODEMS
The HDSL modems are systematically tested by R&D in order to remove modems
which are suspected to lead problems on the field. The list of the recommended
HDSL 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 rapid
deployment.
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 be
installed. Indeed the clearance has to be 60% of the first Fresnel zone, plus a
security factor (5 or 6 m) for errors on terrain data. The 60% F1 is calculated for
standard atmosphere (k=4/3) and the atmosphere can change, needing the link a
better 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 that
sometimes a repeater is needed to cover this distance. In order to calculate the
unavailability due to rain, the rain zone where the link is going to be installed, has to
be 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 by
the operator in order to meet its quality requirements. For example, the availability
due to propagation in a 1+0 (nonprotected) can be 99.99% of the annual time; for this
objective, 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 the
tower, or the place where the antenna is going to be installed. The tilt and twist of the
tower, 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 this
depends 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 interference
reduces the threshold, which means that the fade margin decreases and the link will
be unavailable for more time than the time it was calculated for. Alternate polarization
(cross polarization discrimination) and high gain antennas (more directivity) can
offset these effects.
For further information, please refer to the web pages of the transmissions group at
the 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 microwave
transmissions: 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 km
1250 km1250 km 25000 km
Local
grade
Local
grade
Medium
grade
Medium
grade
High
grade
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:
Degraded
Minutes
Severely
Errored
Seconds
Errored
Seconds

PE /IRC/APP/0079 01.08 / EN 12/04/99
Depending on the configuration local or medium grade links are recommended for
Abis interface. Medium grade quality is 50% to 100% more expensive than local
grade as it requires redundant equipment. It must be proposed only if specified by
customer.
7.5.3 MICROWAVE CONFIGURATIONS
It is possible to combine the drop and insert functionality of the BTS product and the
microwaves product in order to insure the transmission security and capacity. The
following configurations are given as example.
Figure 16: Chain Drop&Insert with microwaves
Figure 17: Loop Drop&Insert with microwaves
Central Office
BSC
TCU
medium or local grade
DMS Switch
BTS BTS BTS
Central Office
TCUDMS Switch
BSC
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 Switch
BSC
BTS
BTSBTS
BTS
BTS
BTS S222
BSC
BTS
1
BTS
2
BTS
3
BTS
4
BTS
5

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 can
occur: 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 wave
guide coupler must be used).
• The second one uses two antennas without wave guide coupler. It allows to
avoid 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 each
available 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 for
each type of BSC. The minimum number of BSCB boards is 2. The quantity of boards depends on
the 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 the
needs, 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 product
version 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 up
to 4 physical channels of LAPD (concentrated with BSCB or non concentrated).
vOne LAPD equipment (SICD ports) supports up to 10 TEI. Note that one TCU
corresponds to one TEI, one BCF corresponds to one TEI, and one TRX
corresponds 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 up
to 8 physical channels of LAPD (concentrated with BSCB or non concentrated).
vOne LAPD equipment (SICD ports) supports up to 15 TEI. Note that one TCU
corresponds to one TEI, one BCF corresponds to one TEI, and one TRX
corresponds 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 for
parenting.
vTwo neighbor sites must be on two different SICDs.
vTwo cells of a same site must be on two different SICDs. Of course this condition
can 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 with
SICD8V than with SICD because the load is only split onto 5 boards as opposed to
10 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 boards
required is zero. The minimum number of BSCB boards is 2. The quantity of boards
depends on the number of LAPD channels (or sites) to be concentrated.
The associated parameter is a class 0 parameter (xSCBConfiguration in the bsc
object). 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 pool
of BSCB boards. When one BSCB fails, the BSC reconfigures the whole
configuration of the failed BSCB onto a free BSCB board (one without any LAPD
mapped on it).
When new concentrated LAPD terminals are declared and LAPD channel locations
are moved from one SICD to another, it is very important to check that a BSCB
remains 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 "BSCB
Eng’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 times
4 LAPD unconcentrated into 1 LAPD concentrated). The limit of 10 TEIs per SICD
port (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 connectivity
Max. of 12 non-concentrated
LapD channels used per BSCB board
Max. of 3 concentrated
LapD channels used per BSCB board
Max. of 8 LapD Equipment used
per SICD8V board (4 LapD equipment
per 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, these
spans are used only for the Ater interface. The others can be used
indiscriminately either for the Abis or the Ater interface but must use some
spread convention.
Spread convention nc. 1
In order to minimize the number of remainning PCMs when a board fails, it is best to
spread the spans of a BTS on different DDTIs.
Spread convention nc. 2
Use the same previous rule when configuring Ater PCMs. Avoid the configuration
of 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 synchronization
problems 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 uses
cross-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

49529487 abis-interface

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49529487 abis-interface