abis interface
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401 - 380 - 349Issue 2.0
November 1999
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of Lucent Technologies and is not to be disclosed or usedexcept in accordance with applicable agreements
Copyright 1999 Lucent TechnologiesUnpublished and Not for Publication
All Rights Reserved
EG19: Abis Interface
Engineering Guidelinefor NR 8.6 and NR 8.5.1
Copyright ©1999 by Lucent Tec hnologies. All Rights R eserved .
This material is protected by the copyright laws of the United States and other countries. It may not bereproduced, distributed, or altered in any fashion by any entity (either internal or external to LucentTechnologies), except in accordance with applicable agreements, contracts, or licensing, without theexpress written consent of the Customer Training and Information Products organization and thebusiness management owner of the material.
Notice
Every effort was made to ensure that the information in this information product (IP) was complete andaccurate at the time of printing. However, information is subject to change.
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iii
Contents
1 INTRODUCTION 1-1
About this Guideline 1-1
Overview 1-1
2 DIMENSIONING THE ABIS INTERFACE FOR E1 2-1
Dimensioning the Abis Interface 2-1
Abis Interface timeslot allocation 2-1
Releases prior to NR8.0 2-1
Abis Interface timeslot allocation 2-3
From release NR 8.0 2-3
Abis Timeslot Usage - Configuration Rules 2-4
Example 1 2-7
Example 2 2-8
Example 3 2-9
Example 4 2-10
Example 5 2-11
Example 6 2-12
Example 7 2-13
3 DIMENSIONING THE ABIS INTERFACE FOR T1 3-1
Dimensioning the Abis Interface 3-1
Abis Interface timeslot allocation 3-23-2
3-1
3-1
2-13
2-12
2-11
2-10
2-9
2-8
2-7
2-4
2-3
2-3
2-1
2-1
2-1
2-1
1-1
1-1
1-1
Contents Abis Interface Engineering Guideline
iv Lucent Technologies –ProprietarySee Notice on first page
Issue 2.0 - November 1999
Releases prior to NR8.0 3-2
Abis Interface timeslot allocation 3-3
Abis Timeslot Usage - Configuration Rules 3-4
Example 1 3-7
Example 2 3-8
Example 3 3-9
Example 4 3-10
Example 5 3-11
Example 6 3-12
Example 7 3-13
Summary 3-14
4 REFERENCES 4-1
References 4-1
5 ACRONYMS 5-1
Acronyms 5-1
COMMENTS FORM 5-35-3
5-1
5-1
4-1
4-1
3-14
3-13
3-12
3-11
3-10
3-9
3-8
3-7
3-4
3-3
3-2
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1-1
1 Introduction
About this Guideline
This Engineering Guideline provides a description of the physical characteristics of the Abis Interface anddefines how it is dimensioned within the “Lucent GSM Network”.
Overview
The Abis Interface supports signaling and traffic circuits between the Base Transceiver Station (BTS-2000) and the Base station Controller Frame (BCF-2000). The E1 Abis Interface is based on a data rateof 2.048 Mbit/s, the T1 Abis interface is based on a data rate of 1.544 Mbit/s. E1 carries 32 x 64 Kbit/schannels, while T1 carries 24 x 64 Kbit/s channels.
Functions implemented at the Abis Interface are:
• Voice/Data traffic exchange• Signaling exchange between the BCF-2000 and BTS-2000• Transport of O&M information between the BTS-2000 and the BCF-2000
The bandwidth of each Abis Interface is shared by 31 timeslots1 for E1 and 24 timeslots for T1. Sometimeslots are allocated to carry traffic and others to carry signaling information.
When the Abis Interface is used in a Type 6 architecture, “Traffic” timeslots are subdivided into 4 x 16Kbit/s subrate GSM1800/GSM900GSM1900 traffic channels.2 The situation is shown schematically inFigure 1 (E1) and Figure 2 (T1).
Dual Band operation
Traffic channels from differing frequency bands may be freely mixed onto a single Abis link following thenormal configuration rules for single band use.
1 E1 has 32 timeslots but timeslot 0 is utilised for frame synchronisation.2 These are termed “full-rate” 16 Kbit/s traffic channels. “Half-rate” 8kbit/s traffic channels will beavailable in the future.
Introduction Abis Interface Engineering Guideline
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BTS-2000 BCF-2000
TS0 TS1 TS31
64Kbit/s
16Kbit
16Kbit
16Kbit
16Kbit
13Kbit
3Kbit
4 Sub-rateT ffichannels in
timeslot
Ove
r-he
ad
Voc
oded
Spe
ech
Bit transferRate
8 Bitframes
2.048 Mb/s
either or
64Kbit
Signallinglink
16Kbit
16Kbit
16Kbit
16Kbit
Lucent release 4method
Lucent release 5method
LAPD signalling concentration
function
Abis PhysicalCharacteristics
Figure 1: Physical characteristics of the E1 Abis Interface.
BTS-2000 BCF-2000
TS0 TS1 TS24
64Kbit/s
16Kbit
16Kbit
16Kbit
16Kbit
13Kbit
3Kbit
4 Sub-rateT ffichannels in
timeslot
Ove
r-he
ad
Voc
oded
Spe
ech
Bit transferRate
8 Bitframes
1.544 Mb/s
either or
64Kbit
Signallinglink
16Kbit
16Kbit
16Kbit
16Kbit
Lucent release 4method
Lucent release 5method
LAPD signalling concentration
function
Abis PhysicalCharacteristics
Figure 2: Physical characteristics of the T1 Abis Interface.
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2 Dimensioning the Abis
Interface for E1
Dimensioning the Abis Interface
Lucent BTS-2000 products can have up to 3 Abis interface connections (e.g. 3 x E1 2.048Mbit/s links).
• 2 Abis interfaces to a BCF-2000• 1 Abis link output to provide the multidrop capability
Alternatively:
• 1 Abis interface to a BCF-2000• 2 Abis interface outputs to provide the multidrop capability
One exception is the Lucent BTS-2000/2C which has a maximum of 2 Abis interfaces:
• 1 Abis interface to a BCF-2000• 1 Abis link output to provide the multi-drop capability.
Abis Interface timeslot allocation
Releases prior to NR8.0
Each TRX connected via the Abis interface requires three timeslots:
• 2 for voice traffic/data• 1 for signaling
Dimensioning the Abis Interface for E1 Abis Interface Engineering Guideline
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Each Cell/Sector connected via the Abis interface requires 1 timeslot for O&M signaling.
Example: for a 3-sectored (3,3,3) site;
# Timeslots = 3 x # TRXs + # Cells
= 3 x 9 + 3 = 30 timeslots required
The Lucent BSS configuration allows a maximum of 7 multi-dropped BTS-2000s on a single Abis
Interface connection.3
The maximum number of TRXs which can be placed on a single Abis is 10.
i.e. 3 x # TRXs + # Cells
= 3 x 10 + 1
= 31 (Max. No. of timeslots available on a single Abis
A single cell cannot be split across different Abis links. An omni 11 or omni 12 cannot be supported withRelease 4 software release. A 3-sectored 4,4,4 or 4,4,3 can be supported by placing the 3rd cell on asecond Abis.
Number of Multidrops
1 2 3 4 5 6 7
Maximum TRXs 10 9 9 9 8 8 8
TimeslotsRequired
31 29 30 31 29 30 31
Table 1: E1 Timeslot allocation summary (without LAPD concentration)
3 Multidrop indicates that more that one BTS can utilise the same Abis interface connection
Dimensioning the Abis Interface for E1 Abis Interface Engineering Guideline
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SYNC ST T T ST T T ST T T ST T T ST T T
ST T T ST T T ST T TT orS07
T orS05
T orS04
T orS03
T orS04
S01T orS06
TR
X1
TR
X2
TR
X3
TR
X4
TR
X5
TR
X6
TR
X7
TR
X8
TR
X9
TR
X10
Where T =Traffic Channel ST = TRX Signalling
S0n = Signalling for Cell n
Figure 3: Timeslot allocation with Release 4 software release.
Abis Interface timeslot allocation
From release NR 8.0 Network Release 8.0 provides the LAPD Link Concentrator Function. This allows the concentration of 4logical signaling links onto one physical timeslot on the Abis Interface (i.e. .4 x 16Kbit/s subrate slots).This allows a more economical use of the Abis transmission capacity. Both TRX related signaling andcell (O&M) related signaling can be combined into a single timeslot, but all signaling channels sharing atimeslot must be in the same cell.
Each TRX connected via the Abis interface requires:
• 2 timeslots for voice traffic/data• 1 timeslot for signaling. 1 timeslot can accommodate signaling for:
− up to 4 TRXs (all TRXs must be in the same cell)
or
− 3 TRXs + 1 O&M ( all TRXs must be in the same cell and O&M must relate tothat cell)
With these capacity increases, a single Abis interface can support up to 12 TRXs in multicell or singlecell configurations
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Abis Timeslot Usage - ConfigurationRules
This Abis LAPD Concentration can be used from GSM 8.0 onwards and on the BTS-2000 (with MRIF)and BTS-2000/2C, but is not usable on the BTS-2000P (with RIF) or the RBS-900. The maximum recommended concentration rate is 4:1 (i.e. one BTC and three RT signaling slots perAbis timeslot or four RT signaling slots per Abis timeslot). If a cell (BTS) requires more than one Abis timeslot containing signaling channels (i.e. cells with morethan 3 RTs) then the load (number of signaling channels) per Abis timeslots should be balanced (asdescribed in table opposite).
Number of Multidrops
1 2 3 4 5 6 7 8 9 10
Maximum TRXs 12 12 12 12 12 12 12 11 11 10
TimeslotsRequired
28 28 30 28 29 30 31 30 31 30
Table 2: E1 Timeslot allocation summary (with LAPD concentration)
Dimensioning the Abis Interface for E1 Abis Interface Engineering Guideline
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No. of TRXsper cell
No of used Abis
timeslots * Usage Concentration
rate 1 1st Abis TS BTC, RT:0 2 2 1st Abis TS BTC, RT:0, 1 3
3 1st Abis TS BTC, RT:0,1, 2
4
1st Abis TS BTC, RT:0, 1 3 4
2nd Abis TS RT:2, 3 2 1st Abis TS BTC, RT:0, 1 3
5 2nd Abis TS RT:2, 3, 4 3 1st Abis TS BTC, RT:0,
1, 2 4
6 2nd Abis TS RT:3, 4, 5 3 1st Abis TS BTC, RT:0,
1, 2 4
7 2nd Abis TS RT:3, 4, 5, 6 4 1st Abis TS BTC, RT:0, 1 3 2nd Abis TS RT:2, 3, 4 3 8 3rd Abis TS RT:5, 6, 7 3 1st Abis TS BTC, RT:0,
1, 2 4
2nd Abis TS RT:3, 4, 5 3 9
3rd Abis TS RT:6, 7, 8 3 1st Abis TS BTC, RT:0,
1, 2 4
2nd Abis TS RT:3, 4, 5, 6 4 10
3rd Abis TS RT:7, 8, 9 3 1st Abis TS BTC, RT:0,
1, 2 4
2nd Abis TS RT:3, 4, 5, 6 4 11
3rd Abis TS RT:7, 8, 9, 10 4 1st Abis TS BTC, RT:0,
1, 2 4
2nd Abis TS RT:3, 4, 5 3 3rd Abis TS RT:6, 7, 8 3
12
4th Abis TS RT:9, 10, 11 3 * Abis timeslot containing signaling channels, this column doesn’t describethe absolute timeslot number.
Table 3: Balancing the Abis load
• The Abis timeslots containing BTC signaling information will be configured on Abis
timeslots 31, 30 and downwards.
• Abis timeslots 1, 2 and upwards will be configured as traffic slots (containing trafficchannels). If an additional RT signaling slot is required, the Abis timeslot behind thelast used “traffic” timeslot will be used.
• Each BTC requires it’s own Abis timeslot. It is impossible to concentrate BTC signalingslots (of different cells) into one 64kbit/s Abis timeslot.
• Due to FEICE-4881 there will be no merge of signaling channels of different cells(BTSs) into one Abis timeslot.
• The Abis timeslots containing BTC signaling channels will be filled with signalingchannels for up to 3 RTs (the number of RT signaling channels depends on thenumber of RTs per cell and is given in Table 1).
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RT signaling and traffic channels:
For each RT a signaling channel is set first and then the traffic channels are created. The first RTsignaling channels will be set to the Abis timeslot containing the BTC signaling channel of the appropriatecell (e.g. timeslot 31). If this Abis timeslot is already filled (as described in Table 1) then a new Abis
timeslot (containing RT signaling channels) will be created, followed by the Abis timeslots containing RTtraffic channels. The same Abis configuration will be used for both BSS types: BCE-2000 and BCF-2000. Remarks:
• This Configuration Rule will be used by the Site Independent Scripts to support thecreation of new BTSs.
• If an additional RT will be installed at a existing BTS the operator is not forced to useTable 1 (For example, if there is a BTS containing 3 RTs with all signaling channelsin TS31 it is not necessary to move the RT signaling channel of RT:2 to the Abis
timeslot containing the signaling information for the new RT:3).
• Possible restrictions in reference to the feature “BTS-2000/2C extension to 10 TRX”are not considered in this Configuration Rule.
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Example 1
For a 3-sectored (4,4,4) site:Traffic Timeslots required = 2 x # TRXs = 2 x 12 = 24
Perform the signaling timeslot calculation on a per cell basis.
# Signaling Timeslots for cell A = # TRX + 1 = 4 + 1= 2 4 4
Signaling Timeslots required for cell B and C are the same in this example.
Total # signaling channels required = 3 x 2 = 6
Total # Timeslots required = # Signaling timeslots + # Traffic timeslots = 6 + 24 = 30
The situation is shown schematically in Figure 4.
SYNC S01 S4T T T T T T T T T S02 S4T T T T T
T T T T S03 S4T T T T T T T TT
TR
X3
Where T =Traffic Channel SnT = Signalling for n TRXs
S0n = Signalling for Cell n
TR
X1
TR
X2
TR
X4
TR
X11
TR
X9
TR
X10
TR
X12
TR
X7
TR
X8
TR
X5
TR
X6
Cell 1
Cell 3Cell 2
Cell 2
Figure 4: Timeslot allocation for 4,4,4 configuration, with Release 5 release.
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Example 2
For a 2 x 2-sectored 3,3 on a single Abis:
Traffic Timeslots required = 2 x # TRXs = 2 x 12 = 24
Perform the signaling timeslot calculation on a per cell basis.
# Signaling Timeslots for cell A = # TRX + 1 = 3 + 1 therefore 1 timeslot required
4 4
Signaling Timeslots required for cell B and C are the same in this example.
Total # signaling channels required = 4 x 1 = 4
Total # Timeslots required = # Signaling timeslots + # Traffic timeslots = 4 + 24 = 28
SYNCS3T+S01
T T T T T T S3T+S02
T T T T T T
S3T+S03 T T T T T T
S3T+S04 T T T T TT
TR
X3
Where T =Traffic Chanel SnT = Signalling for n TRXs
S0n = Signalling for Cell n
TR
X1
TR
X2
TR
X4
TR
X11
TR
X9
TR
X10
TR
X12
TR
X7
TR
X8
TR
X5
TR
X6
Cell 1
Cell 4Cell 3
Cell 2
Figure 5: Timeslot allocation for 2 x 2 sectored 3,3 on a single Abis, using release Release 5 software.
The Lucent BSS configuration at Release 5 allows a maximum of 7 multi-dropped BTSs on a single Abis
Interface connection.
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Example 3
4-4-4 Multicell or Multidrop
Traffic Timeslots required = 2 x # TRXs = 2 x 12 = 24
Perform the signaling timeslot calculation on a per cell basis.
# Signaling Timeslots for cell A = # TRX + 1 = 4 + 1 = 2 4 4
Signaling Timeslots required for cell B and C are the same in this example.
Total # signaling channels required = 3 x 2 = 6
Total # Timeslots required = # Signaling timeslots + # Traffic timeslots = 6 + 24 = 30.
The situation is shown schematically in Table 2 below.
Timeslot Cell 4:1 concentration1 RT:0 Traffic2
TRX1RT:0 Traffic
3 RT:1 Traffic4
TRX2RT:1 Traffic
5 A Signaling RT:2,36 RT:2 Traffic7
TRX3RT:2 Traffic
8 RT:3 Traffic9
TRX4RT:3 Traffic
10 RT:0 Traffic11
TRX1RT:0 Traffic
12 RT:1 Traffic13
TRX2RT:1 Traffic
14 B Signaling RT:2,315 RT:2 Traffic16
TRX3RT:2 Traffic
17 RT:3 Traffic18
TRX4RT:3 Traffic
19 RT:0 Traffic20
TRX1RT:0 Traffic
21 RT:1 Traffic22
TRX2RT:1 Traffic
23 C Signaling RT:2,324 RT:2 Traffic25
TRX3RT:2 Traffic
26 RT:3 Traffic27
TRX4RT:3 Traffic
2829 C Signaling BTC, RT:0,130 B Signaling BTC, RT:0,131 A Signaling BTC, RT:0,1
Table 4: Performing a Timeslots calculation on a per cell basis (4-4-4Multicell)
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Example 4
6-6 Multicell or Multidrop
Traffic Timeslots required = 2 x # TRXs = 2 x 12 = 24
Perform the signaling timeslot calculation on a per cell basis.
# Signaling Timeslots for cell A = # TRX + 1 = 6 + 1 = 2 4 4
Signaling Timeslots required for cell B are the same in this example.
Total # signaling channels required = 2 x 2 = 4
Total # Timeslots required = # Signaling timeslots + # Traffic timeslots = 4 + 24 = 28.
Timeslot Cell 4:1 concentration1 TRX1 RT:0 Traffic2 RT:0 Traffic3 TRX2 RT:1 Traffic4 RT:1 Traffic5 TRX3 RT:2 Traffic6 RT:2 Traffic7 A Signaling RT:3, 4, 58 TRX4 RT:3 Traffic9 RT:3 Traffic10 TRX5 RT:4 Traffic11 RT:4 Traffic12 TRX6 RT:5 Traffic13 RT:5 Traffic14 TRX1 RT:0 Traffic15 RT:0 Traffic16 TRX2 RT:1 Traffic17 RT:1 Traffic18 TRX3 RT:2 Traffic19 RT:2 Traffic20 B Signaling RT:3, 4, 521 TRX4 RT:3 Traffic22 RT:3 Traffic23 TRX5 RT:4 Traffic24 RT:4 Traffic25 TRX6 RT:5 Traffic26 RT:5 Traffic27282930 B Signaling BTC, RT:0,1,231 A Signaling BTC, RT:0,1,2
Table 5: Performing a Timeslots calculation on a per cell basis (6-6 Multicell)
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Example 5
2-2-2-2-2-2 Multidrop (e.g. 6 x BTS-2000/2C)
Traffic Timeslots required = 2 x # TRXs = 2 x 12 = 24
Perform the signaling timeslot calculation on a per cell basis.
# Signaling Timeslots for cell A = # TRX + 1 = 2 + 1 = 1 4 4
Signaling Timeslots required for cell B, C, D, D, E, and F are the same in this example.
Total # signaling channels required = 6 x 1 = 6
Total # Timeslots required = # signaling timeslots + # Traffic timeslots = 6 + 24 = 30.
Timeslot Cell 4:1 concentration1 RT:0 Traffic2
TRX1 RT:0 Traffic
3 RT:1 Traffic4
ATRX2
RT:1 Traffic5 RT:0 Traffic6
TRX1 RT:0 Traffic
7 RT:1 Traffic8
BTRX2
RT:1 Traffic9 RT:0 Traffic10
TRX1 RT:0 Traffic
11 RT:1 Traffic12
CTRX2
RT:1 Traffic13 RT:0 Traffic14
TRX1 RT:0 Traffic
15 RT:1 Traffic16
DTRX2
RT:1 Traffic17 RT:0 Traffic18
TRX1 RT:0 Traffic
19 RT:1 Traffic20
ETRX2
RT:1 Traffic21 RT:0 Traffic22
TRX1 RT:0 Traffic
23 RT:1 Traffic24
FTRX2
RT:1 Traffic2526 F Signaling BTC, RT:0,127 E Signaling BTC, RT:0,128 D Signaling BTC, RT:0,129 C Signaling BTC, RT:0,130 B Signaling BTC, RT:0,131 A Signaling BTC, RT:0,1
Table 6: Performing a Timeslots calculation on a per cell basis (2-2-2-2-2-2 Multicell)
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Example 6
8-4 Multicell or Multidrop
Traffic Timeslots required = 2 x # TRXs = 2 x 12 = 24
Perform the signaling timeslot calculation on a per cell basis.
# Signaling Timeslots for cell A = # TRX + 1 = 4 + 1 = 2 4 4
# Signaling Timeslots for cell B = # TRX + 1 = 8 + 1 = 3 4 4
Total # signaling channels required = 2 + 3 = 5
Total # Timeslots required = # Signaling timeslots + # Traffic timeslots = 5 + 24 = 29.
Timeslot Cell 4:1 concentration1 RT:0 Traffic2
TRX1 RT:0 Traffic
3 RT:1 Traffic4
TRX2 RT:1 Traffic
5 Signaling RT:2, 3, 46 RT:2 Traffic7
TRX3 RT:2 Traffic
8 RT:3 Traffic9
TRX4 RT:3 Traffic
10 RT:4 Traffic11
TRX5 RT:4 Traffic
12 Signaling RT: 5, 6, 713 RT:5 Traffic14
TRX6 RT:5 Traffic
15 RT:6 Traffic16
TRX7 RT:6 Traffic
17 RT:7 Traffic18
A
TRX8 RT:7 Traffic
19 RT:0 Traffic20
TRX1 RT:0 Traffic
21 RT:1 Traffic22
TRX2 RT:1 Traffic
23 Signaling RT: 2, 324 RT:2 Traffic25
TRX3 RT:2 Traffic
26 RT:3 Traffic27
B
TRX4 RT:3 Traffic
282930 B Signaling BTC, RT:0, 131 A Signaling BTC, RT:0, 1
Table 7: Performing a Timeslots calculation on a per cell basis (8-4Multicell)
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Example 7
12 Omnicell
Traffic Timeslots required = 2 x # TRXs = 2 x 12 = 24
Perform the signaling timeslot calculation on a per cell basis.
# Signaling Timeslots for cell A = # TRX + 1 = 12 + 1 = 4 4 4
Total # Timeslots required = # Signaling timeslots + # Traffic timeslots = 4 + 24 = 28.
Timeslot Cell 4:1 concentration1 RT:0 Traffic2
TRX1 RT:0 Traffic
3 RT:1 Traffic4
TRX2 RT:1 Traffic
5 RT:2 Traffic6
TRX3 RT:2 Traffic
7 Signaling RT: 3, 4, 58 RT:3 Traffic9
TRX4 RT:3 Traffic
10 RT:4 Traffic11
TRX5 RT:4 Traffic
12 RT:5 Traffic13
TRX6 RT:5 Traffic
14 Signaling RT: 6, 7, 815 RT:6 Traffic16
TRX7 RT:6 Traffic
17 RT:7 Traffic18
TRX8 RT:7 Traffic
19 RT:8 Traffic20
TRX9 RT:8 Traffic
21 Signaling RT: 9, 10, 1122 RT:9 Traffic23
TRX10 RT:9 Traffic
24 RT:10 Traffic25
TRX11 RT:10 Traffic
26 RT:11 Traffic27
A
TRX12 RT:11 Traffic
28293031 A Signaling BTC, RT:0,1,2
Table 8: Performing a Timeslots calculation on a per cell basis (12Omnicell)
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3-1
3 Dimensioning the AbisInterface for T1
Dimensioning the Abis Interface
Lucent BTS-2000 products can have up to 3 Abis interface connections (e.g. 3 x T1 1.544Mbit/s links).
• 2 Abis interfaces to a BCF-2000• 1 Abis link output to provide the multidrop capability
Alternatively:
• 1 Abis interface to a BCF-2000• 2 Abis interface outputs to provide the multidrop capability
One exception is the Lucent BTS-2000/2C which has a maximum of 2 Abis interfaces:
• 1 Abis interface to a BCF-2000• 1 Abis link output to provide the multi-drop capability.
Dimensioning the Abis Interface for T1 Abis Interface Engineering Guideline
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Abis Interface timeslot allocation
Releases prior to NR8.0
Each TRX connected via the Abis interface requires three timeslots:
• 2 for voice traffic/data• 1 for signaling
Each Cell/Sector connected via the Abis interface requires 1 timeslot for O&M signaling.
Example: for a 3-sectored (2,2,2) site;
# Timeslots = (3 x # TRXs) + # Cells
= (3 x 6) + 3 = 21 timeslots required
The Lucent BSS configuration allows a maximum of 7 multi-dropped BTS-2000s on a single Abis
Interface connection.4
The maximum number of TRXs which can be placed on a single Abis is 7.
i.e. (3 x # TRXs) + # Cells
= (3 x 7) + 1 = 22 timeslots required
A single cell cannot be split across different Abis links.
Number of Multidrops
1 2 3 4 5 6
Maximum TRXs 7 7 7 6 6 6
TimeslotsRequired
22 23 24 22 23 24
Table 9: T1 Timeslot allocation summary (without LAPD concentration)
4 Multidrop indicates that more that one BTS can utilise the same Abis interface connection
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ST T T ST T T S01
TRX6
TRX7
Where T =Traffic Channel ST = TRX Signalling
S0n = Signalling for Cell n
ST T T ST T T ST T T ST T T ST T T
TRX1
TRX2
TRX3
TRX4
TRX5
Figure 6: Timeslot allocation with Release 4 software release.
Abis Interface timeslot allocation
From release NR 8.0
Network Release 8.0 provides the LAPD Link Concentrator Function. This allows the concentration of 4logical signaling links onto one physical timeslot on the Abis Interface (i.e. .4 x 16Kbit/s subrate slots).This allows a more economical use of the Abis transmission capacity. Both TRX related signaling andcell (O&M) related signaling can be combined into a single timeslot, but all signaling channels sharing atimeslot must be in the same cell.
Each TRX connected via the Abis interface requires:
• 2 timeslots for voice traffic/data• 1 timeslot for signaling. 1 timeslot can accommodate signaling for:
− up to 4 TRXs (all TRXs must be in the same cell)
or
− 3 TRXs + 1 O&M ( all TRXs must be in the same cell and O&M must relate tothat cell)
With these capacity increases, a single Abis interface can support up to 10 TRXs in multicell or singlecell configurations
Dimensioning the Abis Interface for T1 Abis Interface Engineering Guideline
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Abis Timeslot Usage - ConfigurationRules
This Abis LAPD Concentration for T1 can be used from GSM 8.0 onwards and on the BTS-2000 (withMRIF2) and BTS-2000/2C, but is not usable on the BTS-2000P (with MRIF, RIF) or the RBS-900. The maximum recommended concentration rate is 4:1 (i.e. one BTC and three RT signaling slots perAbis timeslot or four RT signaling slots per Abis timeslot). If a cell (BTS) requires more than one Abis timeslot containing signaling channels (i.e. cells with morethan 3 RTs) then the load (number of signaling channels) per Abis timeslots should be balanced (asdescribed in table opposite).
Number of Multidrops
1 2 3 4 5 6 7 8
Maximum TRXs 10 10 10 10 9 9 8 8
TimeslotsRequired
23 24 24 24 23 24 23 24
Table 10: T1 Timeslot allocation summary (with LAPD concentration)
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No. of TRXs
per cell No of used Abis
timeslots * Usage Concentration
rate 1 1st Abis TS BTC, RT:0 2 2 1st Abis TS BTC, RT:0, 1 3
3 1st Abis TS BTC, RT:0, 1,2
4
1st Abis TS BTC, RT:0, 1 3 4
2nd Abis TS RT:2, 3 2 1st Abis TS BTC, RT:0, 1 3
5 2nd Abis TS RT:2, 3, 4 3 1st Abis TS BTC, RT:0, 1,
2 4
6 2nd Abis TS RT:3, 4, 5 3 1st Abis TS BTC, RT:0, 1,
2 4
7 2nd Abis TS RT:3, 4, 5, 6 4 1st Abis TS BTC, RT:0, 1 3 2nd Abis TS RT:2, 3, 4 3 8 3rd Abis TS RT:5, 6, 7 3 1st Abis TS BTC, RT:0, 1,
2 4
2nd Abis TS RT:3, 4, 5 3 9
3rd Abis TS RT:6, 7, 8 3 1st Abis TS BTC, RT:0, 1,
2 4
2nd Abis TS RT:3, 4, 5, 6 4 10
3rd Abis TS RT:7, 8, 9 3 * Abis timeslot containing signaling channels, this column doesn’t describethe absolute timeslot number.
Table 11: Balancing the Abis load
• The Abis timeslots containing BTC signaling information will be configured on Abis
timeslots 24, 23 and downwards.
• Abis timeslots 1, 2 and upwards will be configured as traffic slots (containing trafficchannels). If an additional RT signaling slot is required, the Abis timeslot behind thelast used “traffic” timeslot will be used.
• Each BTC requires it’s own Abis timeslot. It is impossible to concentrate BTC signalingslots (of different cells) into one 64kbit/s Abis timeslot.
• Due to FEICE-4881 there will be no merge of signaling channels of different cells(BTSs) into one Abis timeslot.
• The Abis timeslots containing BTC signaling channels will be filled with signalingchannels for up to 3 RTs (the number of RT signaling channels depends on thenumber of RTs per cell and is given in Table 1).
RT signaling and traffic channels:
For each RT a signaling channel is set first and then the traffic channels are created. The first RTsignaling channels will be set to the Abis timeslot containing the BTC signaling channel of the appropriatecell (e.g. timeslot 31). If this Abis timeslot is already filled (as described in Table 1) then a new Abis
timeslot (containing RT signaling channels) will be created, followed by the Abis timeslots containing RTtraffic channels.
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The same Abis configuration will be used for both BSS types: BCE-2000 and BCF-2000. Remarks:
• This Configuration Rule will be used by the Site Independent Scripts to support the
creation of new BTSs.• If an additional RT will be installed at a existing BTS the operator is not forced to
use Table 1 (For example, if there is a BTS containing 3 RTs with all signalingchannels in TS31 it is not necessary to move the RT signaling channel of RT:2 tothe Abis timeslot containing the signaling information for the new RT:3).
• Possible restrictions in reference to the feature “BTS-2000/2C extension to 10TRX” are not considered in this Configuration Rule.
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Example 1
For a 3-sectored (3,3,3) site:Traffic Timeslots required = 2 x # TRXs = 2 x 9 = 18
Perform the signaling timeslot calculation on a per cell basis.
# Signaling Timeslots for cell A = # TRX + 1 = 3 + 1 = 1 4 4
Signaling Timeslots required for cell B and C are the same in this example.
Total # signaling channels required = 3 x 1 = 6
Total # Timeslots required = # Signaling timeslots + # Traffic timeslots = 3 + 18 = 21
The situation is shown schematically in Figure 7
T T
T T T TT T
Where: T =Traffic Channel SnT = Signaling for n TRXs S0n = Signaling for Cell n
S01 +S3T T T T T T T
TR
X3
TR
X1
TR
X2
TR
X7
TR
X9
TR
X6
TR
X8
T T T T
TR
X4
TR
X5
Cell 1
Cell 3
Cell 2
S02 +S3T
S03 +S3T
Figure 7: Timeslot allocation for 3,3,3 configuration, using release Release 5 software.
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Example 2
For a 2 x 2-sectored sites, 2,2 configs on a single Abis:
Traffic Timeslots required = 2 x # TRXs = 2 x 8 = 16
Perform the signaling timeslot calculation on a per cell basis.
# Signaling Timeslots for cell A = # TRX + 1 = 2 + 1 therefore 1 timeslot required
4 4
Signaling Timeslots required for cell B and C are the same in this example.
Total # signaling channels required = 4 x 1 = 4
Total # Timeslots required = # Signaling timeslots + # Traffic timeslots = 4 + 16 = 20
S3T+S01
T T T T
S3T+S03
T T T TS3T+S04
T T T T
TR
X3
Where: T =Traffic Channel SnT = Signaling for n TRXs S0n = Signaling for Cell n
TR
X1
TR
X2
TR
X4
TR
X8
TR
X7
TR
X5
TR
X6
S3T+S02
T T T T
Cell 1
Cell 4Cell 3
Cell 2
Figure 8: Timeslot allocation for 2 x 2 sectored 2,2 on a single Abis, using release Release 5 software.
The Lucent BSS configuration at Release 5 allows a maximum of 7 multi-dropped BTSs on a single Abis
Interface connection.
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Example 3
3,3,3 Multicell or Multidrop
Traffic Timeslots required = 2 x # TRXs = 2 x 9 = 18
Perform the signaling timeslot calculation on a per cell basis.
# Signaling Timeslots for cell A = # TRX + 1 = 3 + 1 = 1 4 4
Signaling Timeslots required for cell B and C are the same in this example.
Total # signaling channels required = 3 x 1 = 3
Total # Timeslots required = # Signaling timeslots + # Traffic timeslots = 3 + 18 = 21.
The situation is shown schematically in Table 2 below.
Timeslot Cell 4:1 concentration1 RT:0 Traffic2
TRX1RT:0 Traffic
3 RT:1 Traffic4
TRX2RT:1 Traffic
5 RT:2 Traffic6
A
TRX3RT:2 Traffic
7 RT:0 Traffic8
TRX1RT:0 Traffic
9 RT:1 Traffic10
TRX2RT:1 Traffic
11 RT:2 Traffic12
B
TRX3RT:2 Traffic
13 RT:0 Traffic14
TRX1RT:0 Traffic
15 RT:1 Traffic16
TRX2RT:1 Traffic
17 RT:2 Traffic18
C
TRX3RT:2 Traffic
19202122 C Signaling BTC, RT:0,1,223 B Signaling BTC, RT:0,1,224 A Signaling BTC, RT:0,1,2
Table 12: Performing a Timeslots calculation on a per cell basis (3,3,3 Multicell)
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Example 4
5,5 Multicell or Multidrop
Traffic Timeslots required = 2 x # TRXs = 2 x 10 = 20
Perform the signaling timeslot calculation on a per cell basis.
# Signaling Timeslots for cell A = # TRX + 1 = 5 + 1 = 2 4 4
Signaling Timeslots required for cell B are the same in this example.
Total # signaling channels required = 2 x 2 = 4
Total # Timeslots required = # Signaling timeslots + # Traffic timeslots = 4 + 20 = 24.
Timeslot Cell 4:1 concentration1 RT:0 Traffic2
TRX1RT:0 Traffic
3 RT:1 Traffic4
TRX2RT:1 Traffic
5 RT:2 Traffic6
TRX3RT:2 Traffic
7 RT:3 Traffic8
TRX4RT:3 Traffic
9 RT:4 Traffic10
TRX5RT:4 Traffic
11
A
Signaling RT: 0, 1, 212 RT:0 Traffic13
TRX1RT:0 Traffic
14 RT:1 Traffic15
TRX2RT:1 Traffic
16 RT:2 Traffic17
TRX3RT:2 Traffic
18 RT:3 Traffic19
TRX4RT:3 Traffic
20 RT:4 Traffic21
TRX 5RT:4 Traffic
22
B
Signaling RT: 0, 1, 223 B Signaling BTC, RT: 3, 424 A Signaling BTC, RT: 3, 4
Table 13: Performing a Timeslots calculation on a per cell basis (5,5 Multicell)
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Example 5
2,2,2,2 Multidrop (e.g. 6 x BTS-2000/2C)
Traffic Timeslots required = 2 x # TRXs = 2 x 8 = 16
Perform the signaling timeslot calculation on a per cell basis.
# Signaling Timeslots for cell A = # TRX + 1 = 2 + 1 = 1 4 4
Signaling Timeslots required for cell B, C, D and E are the same in this example.
Total # signaling channels required = 4 x 1 = 4
Total # Timeslots required = # signaling timeslots + # Traffic timeslots = 4 + 16 = 20.
Timeslot Cell 4:1 concentration1 RT:0 Traffic2
TRX1 RT:0 Traffic
3 RT:1 Traffic4
ATRX2
RT:1 Traffic5 RT:0 Traffic6
TRX1 RT:0 Traffic
7 RT:1 Traffic8
BTRX2
RT:1 Traffic9 RT:0 Traffic10
TRX1 RT:0 Traffic
11 RT:1 Traffic12
CTRX2
RT:1 Traffic13 RT:0 Traffic14
TRX1 RT:0 Traffic
15 RT:1 Traffic16
DTRX2
RT:1 Traffic1718192021 D Signaling BTC, RT:0,122 C Signaling BTC, RT:0,123 B Signaling BTC, RT:0,124 A Signaling BTC, RT:0,1
Table 14: Performing a Timeslots calculation on a per cell basis (2,2,2,2Multicell)
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Example 6
6, 4 Multicell or Multidrop
Traffic Timeslots required = 2 x # TRXs = 2 x 10 = 20
Perform the signaling timeslot calculation on a per cell basis.
# Signaling Timeslots for cell A = # TRX + 1 = 6 + 1 = 2 4 4
# Signaling Timeslots for cell B = # TRX + 1 = 4 + 1 = 2 4 4
Total # signaling channels required = 2 + 2 = 4
Total # Timeslots required = # Signaling timeslots + # Traffic timeslots = 4 + 20 = 24.
Timeslot Cell 4:1 concentration1 RT:0 Traffic2
TRX1RT:0 Traffic
3 RT:1 Traffic4
TRX2RT:1 Traffic
5 RT:2 Traffic6
TRX3RT:2 Traffic
7 RT:3 Traffic8
TRX4RT:3 Traffic
9 RT:4 Traffic10
TRX5RT:4 Traffic
11 RT:5 Traffic12
TRX6RT:5 Traffic
13
A
Signaling RT:2, 3, 4, 514 RT:0 Traffic15
TRX1RT:0 Traffic
16 RT:1 Traffic17
TRX2RT:1 Traffic
18 RT:2 Traffic19
TRX3RT:2 Traffic
20 RT:3 Traffic21
TRX4RT:3 Traffic
22
B
Signaling RT: 2, 323 B Signaling BTC, RT:0, 124 A Signaling BTC, RT:0, 1
Table 15: Performing a Timeslots calculation on a per cell basis (6-4Multicell)
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Example 7
10 Omnicell
Traffic Timeslots required = 2 x # TRXs = 2 x 10 = 20
Perform the signaling timeslot calculation on a per cell basis.
# Signaling Timeslots for cell A = # TRX + 1 = 10 + 1 = 3 4 4
Total # Timeslots required = # Signaling timeslots + # Traffic timeslots = 3 + 20 = 23.
Timeslot Cell 4:1 concentration1 RT:0 Traffic2
TRX1 RT:0 Traffic
3 RT:1 Traffic4
TRX2 RT:1 Traffic
5 RT:2 Traffic6
TRX3 RT:2 Traffic
7 Signaling RT: 3, 4, 5, 68 RT:3 Traffic9
TRX4 RT:3 Traffic
10 RT:4 Traffic11
TRX5 RT:4 Traffic
12 RT:5 Traffic13
TRX6 RT:5 Traffic
14 Signaling RT: 7, 8, 915 RT:6 Traffic16
TRX7 RT:6 Traffic
17 RT:7 Traffic18
TRX8 RT:7 Traffic
19 RT:8 Traffic20
TRX9 RT:8 Traffic
21 RT:9 Traffic22
A
TRX10 RT:9 Traffic
2324 A Signaling BTC, RT:0,1,2
Table 16: Performing a Timeslots calculation on a per cell basis (10Omnicell)
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Summary
Table 17 gives a brief summary of the Abis maximum capacities:
Max. BTSs on drop & insert Max. No. of TRXsE1 T1 E1 T1
NR to 8.0 (without LAPD concentration)LM4
7 (see note 2) 6 (see note 2) 10 (see note 1) 7 (see note 1)
NR from 8.0(with LAPD concentration) LM5 10 (see note 2) 8 (see note 2) 12 (see note 1) 10 (see note 1)
Table 17: A summary of the Abis maximum capacities
Note 1: Figures are based on a single cell containing the maximum number of TRXs.
Note 2: Figures are based on the maximum number of cells each containing one TRX.
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4 References
References
[Ref. 1] BSS Network Configuration Training Course (WL9011), Issue A, June 19 1997
[Ref. 2] Lucent Network Design Tool (NDT). Available through Offer Engineering, Swindon,England
[Ref. 3] Network Configuration Guidelines
[Ref. 4] Abis signalling link concentration (EG 1)
References Abis Interface Engineering Guideline
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5-1
5 Acronyms
Acronyms
ACC Advanced Communications Cards
ACE Antenna Coupling Equipment
ACU Accessory Control Unit
BCF Base station Controller Frame
BHCA Busy Hour Call Attempts
BSS Base station Sub-System
BTC BTS Central Controller
BTS Base Transceiver Frame
DCE Data Communications Equipment
DFU Digital Facility Unit
DTE Data Terminal Equipment
GOS Grade Of Service
GMSK Gaussian Minimum Shift Keying
GSM Global System for Mobile communications
HP Hewlett Packard
ITU-T International Telecommunications Union - Telecommunications
LAPD Link Access Procedural type D
MSC Mobile service Switching Centre
MRIF Mini Rack Interface
Acronyms Abis Interface Engineering Guideline
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NDT Network Design Tool
NSAP Network service Access Point
O&M Operations & Maintenance
OMC Operations and Maintenance Centre
PCM30 Pulse Code Modulation
RBS-900 Radio Base Station 900
RIF Rack Interface
RT Radio Terminal
SDFU Sub-rate Digital Facility Unit
SS7 ITU-T Signaling System No. 7
STF Speech Transcoding Frame
TRX Transceiver
BCF Base Controller Frame
BSS Base Station System
BTC BTS Central Controller
BTS Base Transceiver System
GSM Global System for Mobile communication
ITU-T International Telecommunications Union - Telecommunications
LAPD Link Access Procedural type D
MRIF Mini Rack Interface
NDT Network Design Tool
O&M Operations & Maintenance
PCM30 Peripheral Module Channel
RBS-900 Radio Base Station 900
RIF Rack Interface
RT Radio Terminal
TRX Transceiver
Comments Form Abis Interface Engineering Guideline
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Comments FormDocument No: 401 - 380 - 349 Issue No: 2.0 Date: Nov 1999
Title: EG19: Abis Interface Engineering Guideline
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