Abis Interface

EG19: Abis Interface Engineering Guideline for NR 8.6 and NR 8.5.1

401 - 380 - 349 Issue 2.0 November 1999 Lucent Technologies - Proprietary This document contains proprietary information of Lucent Technologies and is not to be disclosed or used except in accordance with applicable agreements Copyright  1999 Lucent Technologies Unpublished and Not for Publication All Rights Reserved

Copyright ©1999 by Lucent Technologies. All Rights Reserved. This material is protected by the copyright laws of the United States and other countries. It may not be reproduced, distributed, or altered in any fashion by any entity (either internal or external to Lucent Technologies), except in accordance with applicable agreements, contracts, or licensing, without the express written consent of the Customer Training and Information Products organization and the business management owner of the material. Notice Every effort was made to ensure that the information in this information product (IP) was complete and accurate at the time of printing. However, information is subject to change.

Contents

1

2

INTRODUCTION

1-1

About this Guideline

1-1

Overview

1-1

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


2-3 2-3

From release NR 8.0 Abis Timeslot Usage - Configuration Rules

3

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

DIMENSIONING THE ABIS INTERFACE FOR T1

3-1

Dimensioning the Abis Interface

3-1


3-2

Issue 2.0- November 1999

Lucent Technologies – Proprietary See Notice on first page

iii

Contents

Abis Interface Engineering Guideline

Releases prior to NR8.0

3-2


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 4

REFERENCES

4-1

References

4-1

ACRONYMS

5-1

Acronyms

5-1

COMMENTS FORM

5-3

5

iv

3-14


Issue 2.0 - November 1999

1

Introduction

About this Guideline This Engineering Guideline provides a description of the physical characteristics of the Abis Interface and defines how it is dimensioned within the “Lucent GSM Network”.

Overview The Abis Interface supports signaling and traffic circuits between the Base Transceiver Station (BTS2000) and the Base station Controller Frame (BCF-2000). The E1 Abis Interface is based on a data rate of 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/s channels, 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. Some timeslots 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 16 2 Kbit/s subrate GSM1800/GSM900GSM1900 traffic channels. The situation is shown schematically in Figure 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 the normal configuration rules for single band use. 1

E1 has 32 timeslots but timeslot 0 is utilised for frame synchronisation. These are termed “full-rate” 16 Kbit/s traffic channels. “Half-rate” 8kbit/s traffic channels will be available in the future. 2



1-1

Introduction


BTS-2000

BCF-2000 2.048 Mb/s

TS0

TS31

TS1

8 Bit frames

either Bit transfer Rate

64Kbit/s

16 Kbit

16 Kbit

16 Kbit

4 Sub-rate channels in T ffi timeslot

16 Kbit

64Kbit Signalling link

16 Kbit

16 Kbit

16 Kbit

Lucent release 5 method LAPD signalling concentration

Lucent release 4 method

function

Abis Physical Characteristics

13 Kbit

Overhead

Vocoded Speech

3 Kbit

16 Kbit

or

Figure 1: Physical characteristics of the E1 Abis Interface.

BTS-2000

BCF-2000 1.544 Mb/s

TS0

TS24

TS1

8 Bit frames

either Bit transfer Rate

64Kbit/s

16 Kbit

16 Kbit

Overhead

3 Kbit

16 Kbit

13 Kbit

16 Kbit

64Kbit Signalling link

16 Kbit

16 Kbit

16 Kbit



LAPD signalling concentration function

Abis Physical Characteristics

Vocoded Speech

16 Kbit

4 Sub-rate channels in T ffi timeslot

or

Figure 2: Physical characteristics of the T1 Abis Interface.

1-2



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

• •

1 Abis interface to a BCF-2000 2 Abis interface outputs to provide the multidrop capability

Alternatively:

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



2-1



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 3 Interface connection.

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 with rd Release 4 software release. A 3-sectored 4,4,4 or 4,4,3 can be supported by placing the 3 cell on a second Abis.

Number of Multidrops

1

2

3

4

5

6

7

Maximum TRXs

10

9

9

9

8

8

8

Timeslots Required

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

2-2




T

ST

T

T

ST

T

T

ST

T

T

ST

T

T

T or S07

T or S06

T

TRX5

ST

TRX8

T

TRX7

T

TRX6

ST

T

T or S05

T or S04

T or S03

T or S04

S01

TRX10

T

TRX4

ST

TRX9

T

TRX3

T

TRX2

ST

TRX1

SYNC


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 4 logical 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 and cell (O&M) related signaling can be combined into a single timeslot, but all signaling channels sharing a timeslot 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)

−

3 TRXs + 1 O&M ( all TRXs must be in the same cell and O&M must relate to that cell)

or

With these capacity increases, a single Abis interface can support up to 12 TRXs in multicell or single cell configurations



2-3



Abis Timeslot Usage - Configuration Rules 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 per Abis 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 more than 3 RTs) then the load (number of signaling channels) per Abis timeslots should be balanced (as described 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

Timeslots Required

28

28

30

28

29

30

31

30

31

30

Table 2: E1 Timeslot allocation summary (with LAPD concentration)

2-4




No. of TRXs per cell 1 2

No of used Abis timeslots * 1st Abis TS st 1 Abis TS st 1 Abis TS


Usage

Concentration rate 2 3 4

BTC, RT:0 BTC, RT:0, 1 BTC, RT:0, 3 1, 2 st 1 Abis TS BTC, RT:0, 1 3 4 nd RT:2, 3 2 2 Abis TS st 1 Abis TS BTC, RT:0, 1 3 5 nd RT:2, 3, 4 3 2 Abis TS st 1 Abis TS BTC, RT:0, 4 1, 2 6 nd RT:3, 4, 5 3 2 Abis TS st 1 Abis TS BTC, RT:0, 4 1, 2 7 nd RT:3, 4, 5, 6 4 2 Abis TS st 1 Abis TS BTC, RT:0, 1 3 nd 8 2 Abis TS RT:2, 3, 4 3 rd RT:5, 6, 7 3 3 Abis TS st 1 Abis TS BTC, RT:0, 4 1, 2 9 nd 2 Abis TS RT:3, 4, 5 3 rd RT:6, 7, 8 3 3 Abis TS st 1 Abis TS BTC, RT:0, 4 1, 2 10 nd 2 Abis TS RT:3, 4, 5, 6 4 rd RT:7, 8, 9 3 3 Abis TS st 1 Abis TS BTC, RT:0, 4 1, 2 11 nd 2 Abis TS RT:3, 4, 5, 6 4 rd RT:7, 8, 9, 10 4 3 Abis TS st 1 Abis TS BTC, RT:0, 4 1, 2 nd 2 Abis TS RT:3, 4, 5 3 12 rd 3 Abis TS RT:6, 7, 8 3 th RT:9, 10, 11 3 4 Abis TS * Abis timeslot containing signaling channels, this column doesn’t describe the 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 traffic channels). If an additional RT signaling slot is required, the Abis timeslot behind the last used “traffic” timeslot will be used. Each BTC requires it’s own Abis timeslot. It is impossible to concentrate BTC signaling slots (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 signaling channels for up to 3 RTs (the number of RT signaling channels depends on the number of RTs per cell and is given in Table 1).



2-5



RT signaling and traffic channels: For each RT a signaling channel is set first and then the traffic channels are created. The first RT signaling channels will be set to the Abis timeslot containing the BTC signaling channel of the appropriate cell (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 RT traffic channels. The same Abis configuration will be used for both BSS types: BCE-2000 and BCF-2000.

Remarks:

• • •

2-6

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 signaling channels in 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.





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

4 + 1= 2 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.

T

T

T

T

T

S4T

T

T

T

T

T

T

T

T

S4T

T

T

T

T

TRX12

S03

TRX9

TRX8

T

TRX11

Cell 3

T

TRX7

T

S02

TRX10

Cell 2 T

T

TRX5

T

TRX4

T

TRX3

S4T

TRX2

S01

TRX1

SYNC

Cell 2

TRX6

Cell 1

Where T =Traffic Channel SnT = Signalling for n TRXs S0n = Signalling for Cell n

Figure 4: Timeslot allocation for 4,4,4 configuration, with Release 5 release.



2-7



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

T

S3T+ S02

T

T

T

T

T

Cell 4 T

T

S3T+ S04

T

T

TRX10

T

TRX9

T

TRX8

T

TRX7

T

T

T

T

T

T

TRX12

Cell 3 S3T+ S03

T

TRX5

T

TRX11

T

TRX4

T

TRX3

T

TRX2

S3T+ S01

TRX1

SYNC

Cell 2

TRX6

Cell 1

Where T =Traffic Chanel SnT = Signalling for n TRXs S0n = Signalling for Cell n

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.

2-8





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

4+1=2 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 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

Cell

A

B

C

C B A

4:1 concentration RT:0 Traffic TRX1 RT:0 Traffic RT:1 Traffic TRX2 RT:1 Traffic Signaling RT:2,3 RT:2 Traffic TRX3 RT:2 Traffic RT:3 Traffic TRX4 RT:3 Traffic RT:0 Traffic TRX1 RT:0 Traffic RT:1 Traffic TRX2 RT:1 Traffic Signaling RT:2,3 RT:2 Traffic TRX3 RT:2 Traffic RT:3 Traffic TRX4 RT:3 Traffic RT:0 Traffic TRX1 RT:0 Traffic RT:1 Traffic TRX2 RT:1 Traffic Signaling RT:2,3 RT:2 Traffic TRX3 RT:2 Traffic RT:3 Traffic TRX4 RT:3 Traffic Signaling Signaling Signaling

BTC, RT:0,1 BTC, RT:0,1 BTC, RT:0,1

Table 4: Performing a Timeslots calculation on a per cell basis (4-4-4 Multicell)



2-9



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 = 4

6 + 1 = 2 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 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

Cell

4:1 concentration RT:0 Traffic RT:0 Traffic TRX2 RT:1 Traffic RT:1 Traffic TRX3 RT:2 Traffic RT:2 Traffic Signaling RT:3, 4, 5 TRX4 RT:3 Traffic RT:3 Traffic TRX5 RT:4 Traffic RT:4 Traffic TRX6 RT:5 Traffic RT:5 Traffic TRX1 RT:0 Traffic RT:0 Traffic TRX2 RT:1 Traffic RT:1 Traffic TRX3 RT:2 Traffic RT:2 Traffic Signaling RT:3, 4, 5 TRX4 RT:3 Traffic RT:3 Traffic TRX5 RT:4 Traffic RT:4 Traffic TRX6 RT:5 Traffic RT:5 Traffic TRX1

A

B

B A

Signaling Signaling

BTC, RT:0,1,2 BTC, RT:0,1,2

Table 5: Performing a Timeslots calculation on a per cell basis (6-6 Multicell)

2-10





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 = 4

2 + 1 = 1 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 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

Cell TRX1 A TRX2 TRX1 B TRX2 TRX1 C TRX2 TRX1 D TRX2 TRX1 E TRX2 TRX1 F TRX2 F E D C B A

4:1 concentration RT:0 Traffic RT:0 Traffic RT:1 Traffic RT:1 Traffic RT:0 Traffic RT:0 Traffic RT:1 Traffic RT:1 Traffic RT:0 Traffic RT:0 Traffic RT:1 Traffic RT:1 Traffic RT:0 Traffic RT:0 Traffic RT:1 Traffic RT:1 Traffic RT:0 Traffic RT:0 Traffic RT:1 Traffic RT:1 Traffic RT:0 Traffic RT:0 Traffic RT:1 Traffic RT:1 Traffic

Signaling Signaling Signaling Signaling Signaling Signaling

BTC, RT:0,1 BTC, RT:0,1 BTC, RT:0,1 BTC, RT:0,1 BTC, RT:0,1 BTC, RT:0,1

Table 6: Performing a Timeslots calculation on a per cell basis (2-2-2-22-2 Multicell)



2-11



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 # TRX + 1 = 4

# Signaling Timeslots for cell B =

4 + 1 = 2 4 8 + 1 = 3 4

Total # signaling channels required = 2 + 3 = 5 Total # Timeslots required = # Signaling timeslots + # Traffic timeslots = 5 + 24 = 29. Timeslot 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

Cell

A

B

B A

4:1 concentration RT:0 Traffic TRX1 RT:0 Traffic RT:1 Traffic TRX2 RT:1 Traffic Signaling RT:2, 3, 4 RT:2 Traffic TRX3 RT:2 Traffic RT:3 Traffic TRX4 RT:3 Traffic RT:4 Traffic TRX5 RT:4 Traffic Signaling RT: 5, 6, 7 RT:5 Traffic TRX6 RT:5 Traffic RT:6 Traffic TRX7 RT:6 Traffic RT:7 Traffic TRX8 RT:7 Traffic RT:0 Traffic TRX1 RT:0 Traffic RT:1 Traffic TRX2 RT:1 Traffic Signaling RT: 2, 3 RT:2 Traffic TRX3 RT:2 Traffic RT:3 Traffic TRX4 RT:3 Traffic

Signaling Signaling

BTC, RT:0, 1 BTC, RT:0, 1


2-12





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 = 4

12 + 1 = 4 4

Total # Timeslots required = # Signaling timeslots + # Traffic timeslots = 4 + 24 = 28. Timeslot 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

Cell

A

A

4:1 concentration RT:0 Traffic TRX1 RT:0 Traffic RT:1 Traffic TRX2 RT:1 Traffic RT:2 Traffic TRX3 RT:2 Traffic Signaling RT: 3, 4, 5 RT:3 Traffic TRX4 RT:3 Traffic RT:4 Traffic TRX5 RT:4 Traffic RT:5 Traffic TRX6 RT:5 Traffic Signaling RT: 6, 7, 8 RT:6 Traffic TRX7 RT:6 Traffic RT:7 Traffic TRX8 RT:7 Traffic RT:8 Traffic TRX9 RT:8 Traffic Signaling RT: 9, 10, 11 RT:9 Traffic TRX10 RT:9 Traffic RT:10 Traffic TRX11 RT:10 Traffic RT:11 Traffic TRX12 RT:11 Traffic

Signaling

BTC, RT:0,1,2

Table 8: Performing a Timeslots calculation on a per cell basis (12 Omnicell)



2-13



This page is intentionally left blank

2-14



3

Dimensioning the Abis Interface 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

• •

1 Abis interface to a BCF-2000 2 Abis interface outputs to provide the multidrop capability

Alternatively:

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.



3-1



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 4 Interface connection.

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

Timeslots Required

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

3-2




ST

T

T

ST

TR X1

T

T

ST

TR X2

ST

T

T

ST

TR X6


T

T

ST

TR X3

T

T

T

T

ST

TR X4

T

T

TR X5

S01

TR X7

Where T =Traffic Channel ST = TRX Signalling S0n = Signalling for Cell n

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 4 logical 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 and cell (O&M) related signaling can be combined into a single timeslot, but all signaling channels sharing a timeslot 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)

−

3 TRXs + 1 O&M ( all TRXs must be in the same cell and O&M must relate to that cell)

or

With these capacity increases, a single Abis interface can support up to 10 TRXs in multicell or single cell configurations



3-3



Abis Timeslot Usage - Configuration Rules This Abis LAPD Concentration for T1 can be used from GSM 8.0 onwards and on the BTS-2000 (with MRIF2) 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 per Abis 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 more than 3 RTs) then the load (number of signaling channels) per Abis timeslots should be balanced (as described in table opposite). Number of Multidrops

1

2

3

4

5

6

7

8

Maximum TRXs

10

10

10

10

9

9

8

8

Timeslots Required

23

24

24

24

23

24

23

24

Table 10: T1 Timeslot allocation summary (with LAPD concentration)

3-4




No. of TRXs per cell 1 2

No of used Abis timeslots * st 1 Abis TS 1st Abis TS 1st Abis TS


Usage

Concentration rate 2 3 4

BTC, RT:0 BTC, RT:0, 1 BTC, RT:0, 1, 3 2 st 1 Abis TS BTC, RT:0, 1 3 4 2nd Abis TS RT:2, 3 2 st 1 Abis TS BTC, RT:0, 1 3 5 2nd Abis TS RT:2, 3, 4 3 st 1 Abis TS BTC, RT:0, 1, 4 2 6 nd 2 Abis TS RT:3, 4, 5 3 st 1 Abis TS BTC, RT:0, 1, 4 2 7 nd 2 Abis TS RT:3, 4, 5, 6 4 st 1 Abis TS BTC, RT:0, 1 3 nd 8 2 Abis TS RT:2, 3, 4 3 3rd Abis TS RT:5, 6, 7 3 st 1 Abis TS BTC, RT:0, 1, 4 2 9 nd 2 Abis TS RT:3, 4, 5 3 rd 3 Abis TS RT:6, 7, 8 3 st 1 Abis TS BTC, RT:0, 1, 4 2 10 nd 2 Abis TS RT:3, 4, 5, 6 4 3rd Abis TS RT:7, 8, 9 3 * Abis timeslot containing signaling channels, this column doesn’t describe the 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 traffic channels). If an additional RT signaling slot is required, the Abis timeslot behind the last used “traffic” timeslot will be used. Each BTC requires it’s own Abis timeslot. It is impossible to concentrate BTC signaling slots (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 signaling channels for up to 3 RTs (the number of RT signaling channels depends on the number 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 RT signaling channels will be set to the Abis timeslot containing the BTC signaling channel of the appropriate cell (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 RT traffic channels. Issue 2.0- November 1999


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The same Abis configuration will be used for both BSS types: BCE-2000 and BCF-2000.

Remarks: • •

•

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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 signaling channels in 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.





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 = 4

3+1=1 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

S02 + S3T

T

T

T

T

T

T

T

TRX6

T

TRX4

T

TRX3

T

TRX2

T

TRX1

S01 + S3T

Cell 2

TRX5

Cell 1

Cell 3

T

T

T

T

TRX9

T

TRX8

T

TRX7

S03 + S3T

Where: T =Traffic Channel SnT = Signaling for n TRXs S0n = Signaling for Cell n

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


Total # signaling channels required = 4 x 1 = 4 Total # Timeslots required = # Signaling timeslots + # Traffic timeslots = 4 + 16 = 20

Cell 1 S3T+ S02

T

T

T

Cell 4 T

S3T+ S04

T

T

TRX7

T

TRX6

T

TRX5

T

T

T

T

TRX8

Cell 3 S3T+ S03

T

TRX4

T

TRX3

T

TRX2

T

TRX1

S3T+ S01

Cell 2

Where: T =Traffic Channel SnT = Signaling for n TRXs S0n = Signaling for Cell n

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.

3-8





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 = 4

3+1=1 4


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

Cell TRX1 A

TRX2 TRX3 TRX1

B

TRX2 TRX3 TRX1

C

TRX2 TRX3

C B A

4:1 concentration RT:0 Traffic RT:0 Traffic RT:1 Traffic RT:1 Traffic RT:2 Traffic RT:2 Traffic RT:0 Traffic RT:0 Traffic RT:1 Traffic RT:1 Traffic RT:2 Traffic RT:2 Traffic RT:0 Traffic RT:0 Traffic RT:1 Traffic RT:1 Traffic RT:2 Traffic RT:2 Traffic

Signaling Signaling Signaling

BTC, RT:0,1,2 BTC, RT:0,1,2 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 = 4

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

Cell TRX1 TRX2 A

TRX3 TRX4 TRX5 Signaling TRX1 TRX2

B

TRX3 TRX4 TRX 5

B A


4:1 concentration RT:0 Traffic RT:0 Traffic RT:1 Traffic RT:1 Traffic RT:2 Traffic RT:2 Traffic RT:3 Traffic RT:3 Traffic RT:4 Traffic RT:4 Traffic RT: 0, 1, 2 RT:0 Traffic RT:0 Traffic RT:1 Traffic RT:1 Traffic RT:2 Traffic RT:2 Traffic RT:3 Traffic RT:3 Traffic RT:4 Traffic RT:4 Traffic RT: 0, 1, 2 BTC, RT: 3, 4 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 = 4

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

Cell TRX1 A TRX2 TRX1 B TRX2 TRX1 C TRX2 TRX1 D TRX2

D C B A

4:1 concentration RT:0 Traffic RT:0 Traffic RT:1 Traffic RT:1 Traffic RT:0 Traffic RT:0 Traffic RT:1 Traffic RT:1 Traffic RT:0 Traffic RT:0 Traffic RT:1 Traffic RT:1 Traffic RT:0 Traffic RT:0 Traffic RT:1 Traffic RT:1 Traffic

Signaling Signaling Signaling Signaling

BTC, RT:0,1 BTC, RT:0,1 BTC, RT:0,1 BTC, RT:0,1

Table 14: Performing a Timeslots calculation on a per cell basis (2,2,2,2 Multicell)



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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 = 4

6+1=2 4

# Signaling Timeslots for cell B =

# TRX + 1 = 4

4+1=2 4

Total # signaling channels required = 2 + 2 = 4 Total # Timeslots required = # Signaling timeslots + # Traffic timeslots = 4 + 20 = 24. Timeslot 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24

Cell TRX1 TRX2 TRX3 A

TRX4 TRX5 TRX6 Signaling TRX1 TRX2

B

TRX3 TRX4

B A


4:1 concentration RT:0 Traffic RT:0 Traffic RT:1 Traffic RT:1 Traffic RT:2 Traffic RT:2 Traffic RT:3 Traffic RT:3 Traffic RT:4 Traffic RT:4 Traffic RT:5 Traffic RT:5 Traffic RT:2, 3, 4, 5 RT:0 Traffic RT:0 Traffic RT:1 Traffic RT:1 Traffic RT:2 Traffic RT:2 Traffic RT:3 Traffic RT:3 Traffic RT: 2, 3 BTC, RT:0, 1 BTC, RT:0, 1


3-12





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 = 4

10 + 1 = 3 4

Total # Timeslots required = # Signaling timeslots + # Traffic timeslots = 3 + 20 = 23. Timeslot 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24

Cell

A

A

4:1 concentration RT:0 Traffic TRX1 RT:0 Traffic RT:1 Traffic TRX2 RT:1 Traffic RT:2 Traffic TRX3 RT:2 Traffic Signaling RT: 3, 4, 5, 6 RT:3 Traffic TRX4 RT:3 Traffic RT:4 Traffic TRX5 RT:4 Traffic RT:5 Traffic TRX6 RT:5 Traffic Signaling RT: 7, 8, 9 RT:6 Traffic TRX7 RT:6 Traffic RT:7 Traffic TRX8 RT:7 Traffic RT:8 Traffic TRX9 RT:8 Traffic RT:9 Traffic TRX10 RT:9 Traffic Signaling

BTC, RT:0,1,2

Table 16: Performing a Timeslots calculation on a per cell basis (10 Omnicell)



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Summary Table 17 gives a brief summary of the Abis maximum capacities: Max. BTSs on drop & insert Max. No. of TRXs E1 T1 E1 T1 7 (see note 2) 6 (see note 2) 10 (see note 1) 7 (see note 1)

NR to 8.0 (without LAPD concentration) LM4 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)



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References


This page is intentionally left blank

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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



5-1

Acronyms


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

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Issue No:

2.0

Date:

Nov 1999

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