Bts Fuctional Description

Alcatel-Lucent GSM

BTS Functional Description

BTS Document

Sub-System Description

Release B10

3BK 21227 AAAA TQZZA Ed.03

Status RELEASED

Short title BTS Functional Descr.

All rights reserved. Passing on and copying of this document, useand communication of its contents not permitted without writtenauthorization from Alcatel-Lucent.

BLANK PAGE BREAK

2 / 184 3BK 21227 AAAA TQZZA Ed.03

Contents

Contents

Preface . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11

1 Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 131.1 BTS Role in a GSM Network . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14

1.1.1 Environment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 151.1.2 Functional Architecture . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 161.1.3 Channel Organization . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16

1.2 BTS Functions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 171.2.1 Transmission Functions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 171.2.2 Telecommunication Functions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 171.2.3 O&M Functions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 181.2.4 Support Functions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18

1.3 External Interfaces . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 191.3.1 Air Interface . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 191.3.2 Abis Interface . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 191.3.3 Clock Interface . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 191.3.4 MMI . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 191.3.5 External Alarm Connection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 201.3.6 Power Supply Connection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20

1.4 Signal and Data Processing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 211.4.1 Downlink Signal Processing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 211.4.2 Uplink Signal Processing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 231.4.3 O&M Data Processing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23

2 Channel Organization . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 252.1 Introduction to Channel Organization . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 262.2 Radio Usage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26

2.2.1 Radio Transmission Channels . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 262.2.2 Frequencies . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 262.2.3 Modulation Technique . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26

2.3 Channel Types . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 272.3.1 Signalling Channels . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 272.3.2 Broadcast Channels . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 272.3.3 Common Control Channels . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 282.3.4 Dedicated Control Channels . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 292.3.5 Traffic Channels . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 292.3.6 Packet Switched Channels . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29

2.4 Channel Structure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 302.4.1 26-Multiframe . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 302.4.2 51-Multiframe . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 302.4.3 Superframe . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 312.4.4 Hyperframe . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 312.4.5 Transmit/Receive Timing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31

2.5 Radio Resource Management . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 322.5.1 Layer 3 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 322.5.2 Layer 2 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 342.5.3 Layer 1 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34

3 Transmission Functions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35

3.1 Introduction to Transmission Functions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 363.2 Multiplexing Scheme . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37

3.2.1 Abis Interface . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 373.2.2 Transmission O&M . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 373.2.3 Signalling . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 383.2.4 Traffic . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 383.2.5 Clock . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38

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3.2.6 Network Configuration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 383.3 Abis Interface Physical Connection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 393.4 GPRS Transmission Plane . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 39

4 Telecommunication Functions - Baseband . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 414.1 Introduction to Telecommunication Functions - Baseband . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 424.2 Baseband Processing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42

4.2.1 Speech Transcoding . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 434.2.2 Rate Adaptation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 444.2.3 Channel Encoding and Decoding . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 474.2.4 Interleaving/De-interleaving . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 484.2.5 Encryption/Decryption . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 494.2.6 Demodulation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 50

4.3 Call Management Functions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 514.3.1 Radio Link Recovery . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 514.3.2 Radio Resource Indication . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 514.3.3 Paging . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 514.3.4 Discontinuous Transmission . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 524.3.5 Discontinuous Reception . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 524.3.6 Quality Measurement . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 534.3.7 Power Control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 53

4.4 Supervisory and Control Functions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 544.4.1 Clock Distribution . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 544.4.2 Protocol Management . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 544.4.3 Radio Channel Management . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 544.4.4 Transcoder Time Alignment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 55

5 Telecommunication Functions - RF . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 575.1 Introduction to Telecommunication Functions - RF . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 585.2 RF Processing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 60

5.2.1 RF Carrier Generation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 605.2.2 Frequency Hopping . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 605.2.3 GMSK Modulation and Up-conversion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 625.2.4 Power Amplification and Power Control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 625.2.5 Channel Selection and Conversion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 625.2.6 Signal Amplification . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 635.2.7 A-D Conversion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 635.2.8 Digital Pre-processing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 63

5.3 Control Functions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 645.3.1 RF Hardware Status . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 645.3.2 Frequency Hopping Control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 645.3.3 Clock Management . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 645.3.4 Frequency Synthesizer Programming . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 645.3.5 Alarm Processing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 645.3.6 High/Low Gain Selection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 64

5.4 Coupling Functions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 655.4.1 Isolating . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 655.4.2 Combining . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 655.4.3 Duplexing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 655.4.4 Power Coupling and Detection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 665.4.5 Antenna Pre-amplification . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 665.4.6 Receiver Front-end . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 66

6 O&M and Support Functions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 676.1 O&M Functions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 68

6.1.1 O&M Connections . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 686.1.2 O&M Processing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 696.1.3 RF Self-test . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 716.1.4 Recovery Strategy . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 71

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6.2 Support Functions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 726.2.1 Internal Power Supplies . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 726.2.2 Timing Functions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 726.2.3 Internal Temperature Control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 73

7 BTS Functional Architecture . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 757.1 Introduction to BTS Functional Architecture . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 767.2 G1/G2 BTS Architecture . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 76

7.2.1 Functional Units . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 767.2.2 Functional Block Diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 777.2.3 Interfaces . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 77

7.3 Mapping of Functional Blocks to Functional Units . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 787.3.1 Transmission . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 787.3.2 Telecommunication Baseband . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 797.3.3 Telecommunication RF . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 807.3.4 O&M . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 817.3.5 Support . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 81

8 G1/G2 BTS Functional Units . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 838.1 G1/G2 BTS Functional Units Breakdown . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 848.2 G1/G2 BTS Frame Unit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 84

8.2.1 G1/G2 BTS Frame Unit Functional Entities . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 858.2.2 G1/G2 BTS Frame Unit External Interfaces . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 908.2.3 G1/G2 BTS Frame Unit Submodules . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 918.2.4 G1/G2 BTS Frame Unit Submodule Functions . . . . . . . . . . . . . . . . . . . . . . . . . . . . 928.2.5 G1/G2 BTS Frame Unit Configurations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 93

8.3 G1/G2 BTS Station Unit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 958.3.1 G1/G2 BTS Station Unit Functions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 958.3.2 G1/G2 BTS Station Unit External Interfaces . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 978.3.3 G1/G2 BTS Station Unit Submodules . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 988.3.4 G1/G2 BTS Station Unit Submodule Functions . . . . . . . . . . . . . . . . . . . . . . . . . . . . 998.3.5 G1/G2 BTS Station Unit Configurations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 100

8.4 Carrier Unit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1038.4.1 G1/G2 BTS Carrier Unit Functions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1038.4.2 G1/G2 BTS Carrier Unit External Interfaces . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1058.4.3 G1/G2 BTS Carrier Unit Submodules . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1068.4.4 G1/G2 BTS Carrier Unit Submodule Functions . . . . . . . . . . . . . . . . . . . . . . . . . . . 1078.4.5 G1/G2 BTS Carrier Unit Configurations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 109

8.5 G1/G2 BTS Coupling Unit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1118.5.1 G1/G2 BTS Coupling Unit Functions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1128.5.2 G1/G2 BTS Coupling Unit External Interfaces . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1158.5.3 G1/G2 BTS Coupling Unit Submodules . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1168.5.4 G1/G2 BTS Coupling Unit Submodule Functions . . . . . . . . . . . . . . . . . . . . . . . . . 1178.5.5 G1/G2 BTS Coupling Unit Configurations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 121

9 Software . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1359.1 Overview on Software . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1369.2 Software and Firmware . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 137

9.2.1 Firmware . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1379.2.2 Downloaded Software . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1379.2.3 Software/Firmware Usage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 137

9.3 Software Configuration Data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1389.4 BTS Start-up and Initialization . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 139

9.4.1 Start-up Firmware . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1399.4.2 BTS Download . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1409.4.3 BTS Initialization . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 141

9.5 O&M Software . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1429.5.1 Functions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1429.5.2 Software Modules . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 143

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Contents

9.6 Frame Unit Software . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1489.6.1 SCP Control Functions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1489.6.2 MFP Control Functions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1499.6.3 Software States of the Control Functions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1509.6.4 Encoder . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1529.6.5 Demodulator and Channel Decoder . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 153

9.7 Carrier Unit Software . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1559.7.1 Transmitter . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1559.7.2 Receiver . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 155

10 BTS Objects . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15710.1 Managed Objects and SBL Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15810.2 BTS SBLs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16210.3 BTS Managed Object (SBL) Hierarchy . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16310.4 Allowed Managed Object and SBL States of the G1 BTS Mark 2 and G2 BTS . . . . . . . . . . 164

10.4.1 Allowed States of Managed Object Abis_PCM (SBL Abis-HWAY-TP) . . . . . . . 16410.4.2 Allowed States of Managed Object (SBL) BTS . . . . . . . . . . . . . . . . . . . . . . . . . . . 16410.4.3 Allowed States of Managed Object (SBL) CCF . . . . . . . . . . . . . . . . . . . . . . . . . . . 16510.4.4 Allowed States of Managed Object (SBL) CLLK . . . . . . . . . . . . . . . . . . . . . . . . . . 16510.4.5 Allowed States of Managed Object (SBL) CU . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16610.4.6 Allowed States of Managed Object (SBL) EACB . . . . . . . . . . . . . . . . . . . . . . . . . . 16610.4.7 Allowed States of Managed Object (SBL) FHU . . . . . . . . . . . . . . . . . . . . . . . . . . . 16710.4.8 Allowed States of Managed Object (SBL) FU . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16710.4.9 Allowed States of SBL FU_TS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16810.4.10 Allowed States of Managed Object (SBL) OMU . . . . . . . . . . . . . . . . . . . . . . . . . . 16810.4.11 Allowed States of Managed Object (SBL) RA . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16910.4.12 Allowed States of SBL RTE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 169

10.5 Allowed Managed Object and SBL Actions for the G1 BTS Mark 2 and G2 BTS . . . . . . . . 17010.6 G1 BTS Mark 2 RITs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17110.7 G1 BTS Mark 2 SBLs and RITs Reported to the OMC-R . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17310.8 G2 BTS RITs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17410.9 G2 BTS SBLs and RITs Reported to the OMC-R . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17710.10 BTS RBLs and Local Fault Indication via LEDs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 178

10.10.1 G1 BTS Mark 2 RITs with Corresponding RBL and LED Indications . . . . . . . . 17910.10.2 G2 BTS (GSM 900/1800/1900) RITs with Corresponding RBLs and LED

Indications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18110.10.3 RITs Specific to G2 BTS GSM 900 with Corresponding RBLs and LED

Indications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18210.10.4 RITs Specific to G2 BTS GSM 1800/1900 with Corresponding RBLs and LED

Indications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 183

6 / 184 3BK 21227 AAAA TQZZA Ed.03

Figures

FiguresFigure 1: Logical Position of BTS in BSS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15

Figure 2: Logical Position of BTS in BSS with GPRS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15

Figure 3: BTS Functional Architecture . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16

Figure 4: BTS-BSC Transmission . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36

Figure 5: GPRS Transmission and Signalling Planes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40

Figure 6: Baseband Telecommunication Functions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42

Figure 7: Speech Transcoding for Speech Traffic . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 43

Figure 8: Rate Adaptation for Data Traffic . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45

Figure 9: RF Telecommunication Functions for BTSs with Frequency Hopping using Constant CarrierFrequencies . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 58

Figure 10: RF Telecommunication Functions for BTSs with Frequency Hopping using Programmable CarrierFrequencies . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 59

Figure 11: G1/G2 BTS Functional Units Breakdown . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 77

Figure 12: G1/G2 BTS, Frame Unit Functional Entities and Interfaces . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 85

Figure 13: G1 BTS, Mark2 Multi-board Frame Unit (Without Antenna Diversity) . . . . . . . . . . . . . . . . . . . . . . . . 93

Figure 14: G1 BTS Mark2 Single-board Frame Unit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 93

Figure 15: G2 BTS Three-board Frame Unit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 94

Figure 16: G2 BTS Single-board Frame Unit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 94

Figure 17: G1/G2 BTS, Station Unit Logical Functions and Interfaces . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 96

Figure 18: G1 BTS Station Unit (Master) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 100

Figure 19: G2 BTS Single-carrier Station Unit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 101

Figure 20: G2 BTS Multi-carrier Station Unit with Redundant Timing and Switching Functions . . . . . . . . . 102

Figure 21: G1/G2 BTS, Non-diversity Carrier Unit Functions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 104

Figure 22: G1 BTS Carrier Unit (Antenna Diversity) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 109

Figure 23: G2 BTS Carrier Unit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 110

Figure 24: G1/G2 BTS, Downlink Coupling Functional Block Diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 112

Figure 25: G1/G2 BTS, Uplink Coupling Functional Block Diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 113

Figure 26: G1/G2 BTS, Antenna Pre-amplifier Simplified Block Diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . . 114

Figure 27: G1 BTS Mark2 Two-carrier Downlink Coupling Unit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 123

Figure 28: G1 BTS Mark2 Four-carrier Downlink Coupling Unit Variants . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 123

Figure 29: G1 BTS Mark2 Six-carrier Downlink Coupling Unit Variants . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 124

Figure 30: G1 BTS Mark2 Eight-carrier Downlink Coupling Unit Variants . . . . . . . . . . . . . . . . . . . . . . . . . . . . 125

Figure 31: G2 BTS Single-carrier Downlink Coupling Unit Variants . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 126

Figure 32: G2 BTS Two-carrier Downlink Coupling Unit Variants . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 126

Figure 33: G2 BTS Three to Four-carrier Downlink Coupling Unit Variants . . . . . . . . . . . . . . . . . . . . . . . . . . . 127

Figure 34: G2 BTS Single to Four-carrier Downlink Coupling Unit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 127

Figure 35: G2 BTS Single to Eight-carrier Downlink Coupling Unit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 127

Figure 36: G1 BTS Mark2 Two to Four-carrier Uplink Coupling Unit Variants . . . . . . . . . . . . . . . . . . . . . . . . . 128

Figure 37: G1 BTS Mark2 Two to Four-carrier Diversity Uplink Coupling Unit Variants . . . . . . . . . . . . . . . . . 129

3BK 21227 AAAA TQZZA Ed.03 7 / 184

Figures

Figure 38: G1 BTS Six to Eight-carrier Uplink Coupling Unit Variants . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 130

Figure 39: G1 BTS Mark2 Six to Eight-carrier Diversity Uplink Coupling Unit Variants . . . . . . . . . . . . . . . . . 131

Figure 40: G2 BTS Single/Two-carrier Uplink Coupling Unit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 132

Figure 41: G2 BTS Single to Four-carrier Uplink Coupling Unit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 132

Figure 42: G2 BTS Single to Eight-carrier Uplink Coupling Unit Variants . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 133

Figure 43: BTS Start-Up Sequence . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 139

Figure 44: G1 BTS and G2 BTS Managed Object (SBL) Hierarchy Reported by the OMU/SUM to theOMC-R . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 163

8 / 184 3BK 21227 AAAA TQZZA Ed.03

Tables

TablesTable 1: GSM 900 and GSM 1800 Frequency Ranges . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26

Table 2: TCH/F and TCH/H Types . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29

Table 3: Possible Channel Combinations for Single Time Slot . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30

Table 4: Correspondence Table of Speech Transcoding . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 43

Table 5: Correspondence Table of Rate Adaptation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 46

Table 6: O&M External Connections - Interfaces . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 68

Table 7: O&M Configuration Management Tasks . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 69

Table 8: O&M Fault Management Tasks . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 70

Table 9: Principal G1/G2 BTS Interfaces . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 77

Table 10: Functional Block to Functional Unit Mapping - Transmission . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 78

Table 11: Functional Block to Functional Unit Mapping - Telecommunication Baseband . . . . . . . . . . . . . . . . 79

Table 12: Functional Block to Functional Unit Mapping - Telecommunication RF . . . . . . . . . . . . . . . . . . . . . . . 80

Table 13: Functional Block to Functional Unit Mapping - O&M . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 81

Table 14: Functional Block to Functional Unit Mapping - Support . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 81

Table 15: G1/G2 BTS, Distribution of Frame Unit Functions between Frame Unit Functional Entities . . . . . 86

Table 16: G1/G2 BTS, Frame Unit, External Interfaces . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 90

Table 17: G1/G2 BTS, Frame Unit Functional Entities and Submodules . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 92

Table 18: G1/G2 BTS, Station Unit, External Interfaces . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 97

Table 19: G1/G2 BTS, Station Unit Functions and Submodules . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 99

Table 20: G1/G2 BTS, Carrier Unit Control Function Submodules . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 107

Table 21: G1/G2 BTS, Carrier Unit Downlink Function Submodules . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 107

Table 22: G1/G2 BTS, Carrier Unit Uplink Function Submodules . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 108

Table 23: G1/G2 BTS, Coupling Unit Downlink Function Submodules . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 119

Table 24: G1/G2 BTS, Coupling Unit Uplink Function Submodules . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 120

Table 25: G1 BTS, Coupling Unit Combinations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 121

Table 26: G2 BTS Coupling Unit Combinations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 122

Table 27: BTS Firmware/Software Split . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 137

Table 28: Software and Data Held by BTS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 138

Table 29: BTS Initialization, Units and Functions to be Initialized . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 141

Table 30: O&M Software, Application Functions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 145

Table 31: O&M Software, Interface Handlers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 147

Table 32: SCP and MFP Functions, States of the FSM . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 152

Table 33: Digital Receiver, Functional Sub-Entities . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 156

Table 34: BTS Managed Object and SBL Descriptions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 161

Table 35: G1 BTS and G2 BTS Managed Objects and SBLs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 162

Table 36: Allowed States of Managed Object Abis_PCM (SBL Abis-HWAY-TP) . . . . . . . . . . . . . . . . . . . . . . . 164

Table 37: Allowed States of Managed Object (SBL) BTS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 164

Table 38: Allowed States of Managed Object (SBL) CCF . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 165

Table 39: Allowed States of Managed Object (SBL) CLLK . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 165

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Tables

Table 40: Allowed States of Managed Object (SBL) CU . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 166

Table 41: Allowed States of Managed Object (SBL) EACB . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 166

Table 42: Allowed States of Managed Object (SBL) FHU . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 167

Table 43: Allowed States of Managed Object (SBL) FU . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 167

Table 44: Allowed States of SBL FU_TS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 168

Table 45: Allowed States of Managed Object (SBL) OMU . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 168

Table 46: Allowed States of Managed Object (SBL) RA . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 169

Table 47: Allowed States of SBL RTE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 169

Table 48: Allowed Managed Object and SBL Commands for the G1 BTS and G2 BTS . . . . . . . . . . . . . . . . 170

Table 49: G1 BTS Mark 2 RITs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 172

Table 50: G1 BTS MARK 2 SBLs and RITs Reported to the OMC-R . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 173

Table 51: G2 BTS RITs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 176

Table 52: G2 BTS SBLs and RITs Reported to the OMC-R . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 177

Table 53: G1 BTS Mark 2 RITs with Corresponding RBL and LED Indications . . . . . . . . . . . . . . . . . . . . . . . . 180

Table 54: G2 BTS (GSM 900/1800/1900) RITs with Corresponding RBLs and LED Indications . . . . . . . . . 181

Table 55: RITs Specific to G2 BTS GSM 900 with Corresponding RBLs and LED Indications . . . . . . . . . . 182

Table 56: RITs Specific to G2 BTS GSM 1800/1900 with Corresponding RBLs and LED Indications . . . . 183

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Preface

Preface

Purpose This document provides a functional description of the GSM BTS.

The information provided applies to G1 BTS Mark2 and G2 BTS.

All features and functions described in this document may not be availableon your system.

The purpose of this document is to explain the role of the BTS in a GSMnetwork. This includes a description of:

The logical position of the BTS in the BSS

The functional architecture of the BTS

The way in which the BTS interfaces the land-based telephone system

with Mobile Stations.

What’s New In Edition 03Update with the new equipment naming.

In Edition 02Update of system title.

In Edition 01First release of the document.

Audience This document is intended for:

Telecommunications technicians responsible for installation, configuration,

maintenance and troubleshooting operations on the BTS

Engineers responsible for network and configuration planning

Training departments.

Assumed Knowledge The reader must possess a:

General knowledge of telecommunications systems and terminology

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Preface

Good understanding of GSM concepts

Familiarity with BSS functions and architecture.

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1 Overview

1 Overview

This Overview provides a simplified overview of the BTS and its role in aGSM network.

After explaining the logical position of the BTS in the BSS, the chapter showsthe functional architecture of the BTS. It then outlines how the BTS processesuplink and downlink data to interface the land-based telephone system withMobile Stations.

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1 Overview

1.1 BTS Role in a GSM NetworkThe BTS provides two-way radio communication between the PSTN, andMobile Stations located in a single GSM cell. It also provides a similar linkbetween the Mobile Stations and the rest of the PLMN via the TC. The BTSthus interfaces the digital baseband signals used by the land-based networksand the GSM radio signals used by Mobile Stations.

To achieve its overall function, the BTS provides:

Facilities to transmit and receive appropriate radio signals

Management of the protocols used on the BTS - BSC and BTS - MobileStation links. This provides a communications path ’open’ to GSM standards

Cell-specific O&M functions

Low-level local control, including radio resource management.

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1 Overview

1.1.1 Environment

The following figure shows the logical position of the BTS in the BSS, betweenthe BSC and Mobile Stations currently located in the cell area.

BTS BSC

Other BTS

Mobile Station

Mobile Station

Uplink

Downlink

BSS

PSTN

Cell Area

Mobile Station

Transcoder

Radio Frequency Signalsvia Air Interface

Traffic and Signaling via Abis Interface

Rest of PLMN

Figure 1: Logical Position of BTS in BSS

For systems incorporating GPRS some additional components are required asshown in the following figure. An 9135 MFS is placed in the system betweenthe BSC and the SGSN The 9135 MFS contains a number of PCUs, one ofwhich controls all the GPRS activity for one cell.

BTS BSC

Cell Area

Mobile Station

Mobile Station

Mobile Station

Uplink

Downlink

BSS

TCMobile StationC

SGSN

Traffic and Signaling via Abis Interface

A935 MFS

GbInterface PCU

Radio Frequency Signalsvia Air Interface

Figure 2: Logical Position of BTS in BSS with GPRS

The SGSN (see previous figure) keeps track of the location of individual MobileStations. The SGSN also performs both security functions and access control.GPRS services are not available until the Mobile Station has establishedcontact with the SGSN.

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1 Overview

1.1.2 Functional Architecture

The following figure shows the functional architecture of the BTS.

Baseband FunctionsRF Functions

O&M Functions

Support Functions

Transmit/Receive Antenna

To all Functions

* Diversity configuration only

Abis Interface

Telecommunication Functions

Transmission Functions

Receive Antenna *

Part of the Telecommunications functions are duplicated for Antenna Diversity.

Dataflow through the BTS in the downlink direction

Dataflow through the BTS in the uplink direction

Figure 3: BTS Functional Architecture

1.1.3 Channel Organization

RF signals over the Air Interface carry traffic and signalling/control channelswhich are organized according to GSM recommendations. The allocation andcontrol of these channels are managed by the BTS functions.

Radio Resource Management functions control and organize radio resources tomeet the current operational needs of both the network and individual users.

Systems using GPRS services have additional channel allocation as describedin Chapter Channel Organization (Section 2) .

Channel Organization and Radio Resource Management are described inChapter Channel Organization (Section 2) .

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1 Overview

1.2 BTS FunctionsAs the principal interface between the PSTN and Mobile Stations, the BTSperforms four primary functions. These are:

Transmission functions, which manage the transfer of traffic and control

data between the BTS and BSC.

Telecommunications functions, which manage the transfer of traffic and

control data between the BTS and Mobile Stations.

O&M functions, which supervise the operation of the BTS.

Support functions, which provide a logical and physical environment in

which the BTS functions can be realized.

Communication between the transmission, telecommunications, and O&Mfunctions is managed according to the OS model. The BTS functions areconcerned with Layer 1 (Physical), Layer 2 (Data Link), and Layer 3 (Network)of this model.

1.2.1 Transmission Functions

To minimize operating costs, all data passed between the BTS and the BSCis time-division multiplexed onto a single physical interface. This is the AbisInterface, which carries all the data sent between the BSC and BTS.

Logical links between the BSC and BTS handle the following information:

Signalling data used for control purposes

O&M data for the BTS transmission modules

O&M data for the BTS entities

User data in the form of speech and data traffic.

The Abis Interface is described in greater detail in Chapter TransmissionFunctions (Section 3) .

1.2.2 Telecommunication Functions

There are two primary telecommunication functions:

Baseband Functions

RF Functions.

1.2.2.1 Baseband FunctionsBaseband functions modulate and encode traffic and signalling data fromthe BSC according to GSM recommendations. This data is then sent to theMobile Stations using the RF functions. Traffic and signalling received from theMobile Stations is demodulated and decoded to recover the baseband data.Baseband processing is discussed in Chapter Telecommunication Functions -Baseband (Section 4) .

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1 Overview

1.2.2.2 RF FunctionsRF functions enable traffic and signalling to be sent and received over the AirInterface as a radio signal. A special link layer protocol ensures the reliabletransfer of signalling data over the Air Interface. The RF functions are describedin Chapter Telecommunication Functions - RF (Section 5) .

For Antenna Diversity, the telecommunications functions uplink path isduplicated. The duplicated functions extend from the antenna, through theRF functions, and up to the output of the Channel Decoder in the basebandfunctions.

1.2.3 O&M Functions

O&M functions monitor and control the correct operation of the BTS and itsexternal interfaces. These functions are shared between the BTS and BSC.The BSC provides overall control.

The O&M functions use Layer 2 links for BTS internal communications. Aterminal connected via a MMI is used for local operator control of the BTS.

There are four categories of O&M functions:

Configuration Management

Fault Management

Dedicated Alarm and Control Handling

External Alarm Handling.

The O&M functions also control the operation of the RF Self-tests and managethe actions required by the BTS Recovery Strategy.

The BTS O&M functions are described in Chapter O&M and Support Functions(Section 6) .

1.2.4 Support Functions

The support functions provide a number of services relevant to the internalworking of the BTS. They are:

Clock generation and distribution

External alarm collection

Internal self-tests.

The support functions are also described in Chapter O&M and SupportFunctions (Section 6) .

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1 Overview

1.3 External InterfacesThe BTS uses a number of external interfaces to provide the followinginterfaces and connections:

Air Interface

Abis Interface

Clock Interface

MMI

External Alarm Connection

Power Supply Connection.

1.3.1 Air Interface

The Air Interface is the radio link between the BSS and the Mobile Station.

Different frequency ranges are allocated to the GSM 900 and GSM 1800systems. Each range is divided into two bands. One band is for use by theuplink, the other by the downlink.

The Air Interface functions are described in Chapter Channel Organization(Section 2) .

1.3.2 Abis Interface

Uplink, downlink and control data between the BSC and BTS is carried by theAbis Interface. This interface is specified as a G.703/704 2048 kbit/s PCM link(GSM rec. 04.06).

The Abis Interface and transmission functions are described in ChapterTransmission Functions (Section 3) .

1.3.3 Clock Interface

The Clock Interface enables the BTS to synchronize with other BTSs in eithermaster or slave mode.

Timing functions are described in Chapter O&M and Support Functions(Section 6) .

1.3.4 MMI

A local MMI enables a terminal to be connected for local operator control ofthe BTS.

Refer to the BTS Terminal User Guide for more information about local operatorcontrol of the BTS.

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1 Overview

1.3.5 External Alarm Connection

The external alarm connection function enables the BTS external alarmsources to be interfaced to the O&M functions. The connection is made via thededicated alarm functions.

The external alarm connection function is used only in configurations whereexternal alarm sources are present - e.g., cabinet door switch, smoke detector.

External alarm handling is described in Chapter O&M and Support Functions(Section 6) .

1.3.6 Power Supply Connection

The mains supply voltage for a BTS is determined by the internal power supplymodules fitted. The requirement can be:

DC (-48/-60 VDC nominal)

AC (230 VAC).

The main power connection is filtered and provided with one or more protectionbreakers. Lightning protection is provided for AC power lines.

Refer to the G2 BTS Hardware Description for more information about theBTS power supplies.

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1 Overview

1.4 Signal and Data ProcessingDownlink data flows through the BTS from the Abis Interface to the transmitantenna. Uplink data flows from the receive antenna(s) to the Abis Interface.

The following signal and data processing functions are performed:

Downlink Signal Processing

Uplink Signal Processing

O&M Data Processing.

1.4.1 Downlink Signal Processing

Downlink signal processing consists of the following functions and processes:


Baseband Processing

Channel Organization

Frequency Hopping

Coupling Functions.

1.4.1.1 Transmission FunctionsThe transmission functions demultiplex digital baseband data received viathe Abis Interface:

BTS entity O&M data is passed to the O&M functions.

Transmission O&M data is handled locally by the transmission functions.

Traffic and associated control data is demultiplexed to form up to eight

discrete datastreams, depending on the hardware configuration. These arepassed to the baseband functions for processing.

1.4.1.2 Baseband ProcessingThe baseband functions encode each datastream as a series of data bursts.Each burst occupies one TDMA time slot.

The baseband processing assembles the TDMA bursts into the GSM framehierarchy in accordance with GSM rec. 05.01. This recommendation specifiesa number of time slot groups, within which individual time slots are allocatedto downlink TDMA channels in a cyclical manner.

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1 Overview

1.4.1.3 Channel OrganizationWithin a BTS, a single datastream is dedicated to carry the mandatory BCCH.All other time slots are available to carry baseband traffic data and associatedsignalling channel data.

The associated signalling channel data is carried on the SDCCH. This channelis used for call establishment and location update. It is also used with the SMSand Cell Broadcast features. For more information about channel types,refer to Section 2.3 .

The data bursts are organized into the GSM frame hierarchy, then they aresent to the RF functions. The RF functions generate one or more carrierfrequencies, which are modulated by the downlink data. This enables thedownlink data to be sent over the Air Interface as a radio signal.

1.4.1.4 Frequency HoppingSuccessive TDMA bursts from each datastream can be transmitted on a fixedcarrier frequency. Alternatively, successive bursts can be transmitted ondifferent carrier frequencies, chosen from the set of frequencies generated bythe RF functions. The process of transmitting successive bursts on differentfrequencies is called frequency hopping.

For both methods of burst transmission, the resulting combination of a timeslot and a specific radio frequency creates a GSM channel. This channel isunique within the cell.

Only TCH and SDCCHs are frequency hopped. The BCCH is always senton a constant carrier frequency. Frequency hopping is implemented undercontrol of the FHA.

1.4.1.5 Coupling FunctionsThe RF functions include coupling functions which ensure the efficient transferof RF power to the antenna. The coupling functions also enable the BTStransmitters and receivers to share a single antenna.

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1 Overview

1.4.2 Uplink Signal Processing

Uplink signal processing is essentially the reverse of the downlink processingdescribed in Section Downlink Signal Processing (Section 1.4.1) . The followingfunctions and processes are used:

Channel Decoding

Frequency Hopping

Signal Processing.

1.4.2.1 Channel DecodingRadio signals received from Mobile Stations are routed from the antenna to theRF functions. If antenna diversity is configured, signals from a second antennaprovide the BTS with a choice of two signals. Both signals are combined in theChannel Decoder using the maximum radio combining algorithm.

The RF functions also include a duplexing function, which enables the BTSreceivers to share the transmit antenna.

The RF functions remove the RF carrier and produce samples which representthe data contained in the incoming signals.

1.4.2.2 Frequency HoppingEach uplink channel can be on a fixed carrier frequency, or it can be frequencyhopped by the sending Mobile Station. If frequency hopping is configured,successive databursts associated with an uplink channel are received ondifferent carrier frequencies. This process is implemented under control ofthe FHA.

1.4.2.3 Signal ProcessingThe RF functions send the representative samples to the baseband functions.The baseband functions carry out GMSK demodulation and equalization torecover the baseband data.

The baseband functions send the recovered baseband data to the transmissionfunctions. From here the uplink data is multiplexed onto the Abis Interface.

1.4.3 O&M Data Processing

The O&M functions are connected to all of the BTS functional entities, and also(via the Abis Interface), to the BSC.

The BTS is responsible for its own fault detection and localization. The BSCneed not, therefore, know the internal structure of the BTS. O&M functionsare provided for:


Performance Management

Fault Management.

The O&M functions are described in Chapter O&M and Support Functions(Section 6) .

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1 Overview

24 / 184 3BK 21227 AAAA TQZZA Ed.03

2 Channel Organization


This chapter describes the Air Interface channel organization. The variousfeatures associated with these channels are described in the following sections:

Radio Usage

Channel Types

Channel Structure

Radio Resource Management.

The chapter breaks down each category into individual functions, and explainshow each type of channel is used.

3BK 21227 AAAA TQZZA Ed.03 25 / 184


2.1 Introduction to Channel OrganizationThe Air Interface is the radio link between the BSS and the Mobile Station.

The Air Interface utilizes several channel types that are organized incombinations according to GSM recommendations. The transmission of thesechannels is managed in a logical manner according to the OSI seven-layermodel. The various features associated with these channels are described inthe following sections.

2.2 Radio UsageTwo frequency ranges are allocated to the GSM 900 system and GSM 1800variant. Each range is divided into two bands. One band is for use by theuplink, the other by the downlink.

The number of channels available depends on a number of factors including:

Radio Transmission Channels

Frequencies

Modulation Technique.

2.2.1 Radio Transmission Channels

Radio transmission channels are spaced at 200 kHz intervals within each band.A guard space is left at both ends of each band.

All BTSs use up to eight uplink frequency channels, and up to eight downlinkfrequency channels, according to the desired cell capacity.

2.2.2 Frequencies

The following table shows the uplink and downlink frequencies and the numberof transmission channels available.

System Downlink (MHz) Uplink (MHz) Channels

GSM 900 935 - 960 890 - 915 124

GSM 1800 1805 - 1880 1710 - 1785 374

Table 1: GSM 900 and GSM 1800 Frequency Ranges

2.2.3 Modulation Technique

GSM systems use GMSK modulation, which provides a good compromisebetween spectral efficiency and ease of demodulation.

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2.3 Channel TypesThe allocated uplink and downlink frequency bands are utilized using acombination of FDMA and TDMA.

The use of FDMA and TDMA results in a large number of discrete physicalchannels, each of which can carry traffic or signalling information.

The logical channels carried by the FDMA/TDMA time slots are classifiedas either:

Signalling/Control Channels

TCHs

Packet Switched Channels.

2.3.1 Signalling Channels

Signalling channels are divided into three groups, each containing a number ofchannel types:

BCH

CCCH

DCCH.

2.3.2 Broadcast Channels

BCHs are used to control Mobile Station RF transmissions. They also updateMobile Stations on the status of the cells with which they can communicate.

There are three types of BCH:

FCCHThe Mobile Station uses the FCCH to synchronize its RF transmissionfrequency to the allotted channel. It is also used by the Mobile Station whenthe Mobile Station is first switched on, or otherwise enters a service area.At this point, the FCCH enables the Mobile Station to obtain an approximateindication of the boundaries between time slots. This reveals the position ofTime slot 0, which the FCCH occupies. From this starting point, the MobileStation locates the SCH. It can then time its Random Access burst withinthe available window (see below).

Synchronization ChannelThe SCH provides the Mobile Station with precise information about thetiming of the BTS time slot boundaries. This enables the Mobile Stationto maintain correct frame alignment with the BTS timing schedule. TheMobile Station advances its timing schedule to compensate for changes inMobile Station - BTS distance. (Refer to Section 2.5.1 , under the headingDedicated Channel Management).

BCCHThe BCCH carries general information. This includes the identity ofneighboring cells, maximum cell transmit power and details of theconfiguration of the other signalling channels. In GPRS systems thischannel is known as the PBCCH.

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2.3.3 Common Control Channels

The CCCH is used for access control and is shared between all MobileStations in a cell.

There are three types of CCCH:

RACHThe RACH allows an Mobile Station to access the network. When an MobileStation first detects a BCH carrier, and if a location update is needed, ittries to access the BTS. It does this by sending a random access burst onthe RACH. Timing of the random access burst is based on informationderived from the FCCH/SCH.Once the Mobile Station is camped on a cell, it remains in Idle mode until itneeds to communicate with the BTS. For this purpose, it requests access todedicated radio resources.

Access can be requested:

To originate a call from the MS

In response to a Paging message when a call is originated by the network

When a location update becomes necessary.

The Access request is sent on the RACH in the form of an Access Requestmessage. In GPRS systems this channel is known as the PRACH.

AGCHThe AGCH is used by the BTS to send an Immediate Assignment messageto the MS, following an Access Request. The message allocates an SDCCHto the MS, so that a TCH can be specified for the call. In GPRS systems thischannel is known as the PAGCH

PCHThe PCH is used by the BTS to notify an Mobile Station that there is anincoming call. The Mobile Station responds on the RACH.

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2.3.4 Dedicated Control Channels

DCCHs are allocated to carry control information for a specific Mobile Station.They can be of two types, associated or stand-alone:

ACCH

The ACCH takes two forms, depending on the operational condition ofthe Mobile Station:

SACCHThe SACCH is allocated with a SDCCH or TCH, and is presentthroughout the duration of a call. It carries non-urgent control information,including timing advance data.

FACCHUnlike other channels, the FACCH has no dedicated part of the GSMmultiframe. Instead it ’steals’ capacity in the TCH when it is necessary tosend urgent control information. This process is referred to as bit stealing.

In GPRS systems this channel is known as the PACCH.

SDCCHThe SDCCH is allocated dynamically by an Immediate Assignment messagesent on the AGCH. It is used for low-rate control communication duringcall establishment. The SDCCH specifies the TCH with an Assignmentcommand, and handles all signalling until the TCH is set up. The SDCCH isalso invoked during location update and for SMS.

2.3.5 Traffic Channels

There are four TCH/F types, four Enhanced TCH/F types, and one TCH/H type.These types are shown in the following table.

Channel Type TCH/FEnhancedTCH/F TCH/H

Encoded speech X X X

14.4 kbit/s data X - -




Table 2: TCH/F and TCH/H Types

In order to maximize the use of available bandwidth, TCHs are allocated toMobile Stations only when required. The allocation is therefore made onlywhen a call is established. An SACCH is always allocated with a TCH,as described earlier.

2.3.6 Packet Switched Channels

For GPRS the packet data blocks CS-1 and CS-2 and all packet controlchannels are implemented. All channels configured as TCHs can bedynamically configured for packet switched channels. This dynamicconfiguration is handled by the BSC.

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2.4 Channel StructureA group of one or more channels can be multiplexed onto a single time slot insuccessive TDMA frames, in a cyclical manner.

The following table shows the channel combinations allowed by GSM rec.05.02 Sec. 6.4. Half-rate and enhanced full-rate channel combinations areavailable only in dual-rate hardware configurations.

Multiframe Type Channel Combination

26-multiframe TCH/F + FACCH/F + SACCH/F

- TCH/H + SACCH/H + FACCH/H

51-multiframe BCCH + CCCH + SCH + FCCH

- FCCH + SCH + BCCH + PCH + RACH + AGCH + 4 xSDCCH/4 + SACCH x 4

- BCCH + PCH + RACH + AGCH

- 8 x SDCCH/8 + SACCH x 8

Table 3: Possible Channel Combinations for Single Time Slot

Channels are multiplexed into the following types of frame with a fixedrelationship between transmit and receive timing:

26-Multiframe

51-Multiframe

Superframe

Hyperframe

Transmit/Receive Timing.

2.4.1 26-Multiframe

The simplest example is the TCH and SACCH. These are combined into a 4 x26 TDMA frame cycle, known as the 26-multiframe. The FACCH has noallocation on the time slot - it relies on bit stealing.

2.4.2 51-Multiframe

A second cycle, the 51-multiframe, is used for non-traffic channel combinations,including the BCCH. Due to their differing lengths, the start of the51-multiframes becomes offset with respect to the start of the 26-multiframes.During the resulting time interval, any Mobile Station that is handling a callalso monitors the surrounding cells. The signals that are monitored from thesurrounding cells are the SCH and FCCH signals. The surrounding cells canbe synchronized or unsynchronized. Resulting measurements are sent to theBTS, then to the BSC, which uses them to assess the need for handover.

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2.4.3 Superframe

The 26 and 51-multiframes are themselves framed into superframes.Superframes are made up of 51 sets of 26-multiframes or 26 sets of51-multiframes.

2.4.4 Hyperframe

Superframes are framed into hyperframes. A hyperframe consists of 2048superframes. This enables every frame to be separately numbered over aperiod of approximately 3[frac12] hours. All the frames are synchronized tothe same timing schedule.

2.4.5 Transmit/Receive Timing

The Mobile Stations transmit the uplink three time slots later than the BTStransmits the downlink (minus the transmission delay). Therefore, at any instantthe Mobile Stations need only transmit or receive.

For further details of the Air Interface channel structure, refer to GSM rec. 05.01.

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2.5 Radio Resource ManagementAir Interface communication is managed in OSI-type layers. Although thereare seven layers in the OSI model, the BTS functions are concerned with onlythe three lower layers. These are:

Layer 3 (Network)

Layer 2 (Data Link)

Layer 1 (Physical)

MAC layer.

2.5.1 Layer 3

Layer 3 radio resource functions provide general management of the AirInterface channels. The majority of the control processing is performed in theBSC, the BTS simply acting upon BSC commands. These processes are:

Radio channel selection

Channel establishment

Handover preparation

Dedicated channel management

Common channel management

Flow control.

2.5.1.1 Radio Channel SelectionThe BTS carries out free-channel interference measurements. These enablethe BSC to determine which channels are currently the most suitable foruse by both traffic and signalling.

2.5.1.2 Channel EstablishmentRadio Link Management and Channel State Control functions establish the AirInterface channels assigned by the BSC.

2.5.1.3 Handover PreparationA handover procedure can be initiated by the BSC to maintain or improve callquality once channels have been assigned. The same mechanism can alsobe used to optimize use of the network (e.g., reduce interference, alleviatelocal congestion, etc.). The handover procedure is based on measurementsmade at the Mobile Station and BTS.

The procedure can reallocate the Air Interface channels used in the present cell(intra-cell handover). It can also hand over the Mobile Station to a differentBTS and its associated cell (inter-cell handover). Handover is relevant to bothdedicated and common channels.

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2.5.1.4 Dedicated Channel ManagementDedicated Channel Management functions control the radio communicationbetween the BTS and each Mobile Station. Some control is carried out in theBTS, but overall management of the channels is under control of the BSC.For this purpose, the BSC makes use of measurements carried out for eachchannel in the Mobile Station and in the BTS.

Channel Management is handled as a Layer 3 function, using the RSL betweenthe BSC and the telecommunication functions. The RSL uses the LAPD.

The dedicated channel management functions are:

Power ControlIn order to minimize Mobile Station power consumption and co-channelinterference, the Mobile Station adjusts its transmit power to an acceptableminimum. The power level is based on uplink signal strength measurementsmade in the BTS.Similar measurements are made in the Mobile Station for the receivedsignal strength on the downlink. Measurement results are sent to the BTS,which sets the transmitter power output for each time slot. BCCH time slotsare transmitted at constant power.In a GPRS system there is no power control on the downlink. Uplink powercontrol is still performed by the Mobile Station, based on configurationparameters set by the 9135 MFS.

Timing AdvanceAs the distance between a Mobile Station and the BTS changes, bursttransmissions from the Mobile Station must remain aligned with the allocatedAir Interface time slots. Each Mobile Station therefore advances its bursttransmission time, to compensate for changes in the radio propagation delay.This advance is made relative to the basic schedule the Mobile Stationderives from received bursts. Timing advance changes for each MobileStation are calculated within the BTS, which sends them to the MobileStation on the SACCH twice every second.For GPRS systems the timing advance is transmitted from the BTS to theMobile Station every 26th TDMA frame. This is achieved via the PTCCH.The BTS also controls the timing between the BTS and 9135 MFS.

Timing Advance - extended cellThe maximum timing advance permitted with GSM networks is equivalentto 63 bits. This restricts the Mobile Station to BTS distance to a radius ofapproximately 35 km. For GSM 900 networks only, this distance can beincreased by using an extended cell configuration.Extended cell operation inserts an additional 60 bit timing correction to bothreceived and transmitted signals. With this mechanism in place, the burstsare realigned with the scheduled time slot boundaries so that processingcan properly take place.

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2.5.1.5 Common Channel ManagementCommon Channel Management functions use BCHs to handle shared controlcommunication between the BTS and Mobile Stations.

The common channel management functions are:

Channel RequestWhen an Mobile Station needs to access the network, it sends a randomaccess request to the BTS. The BTS sends the request to the BSC togetherwith reception measurements taken by the BTS.

Channel SchedulingChannel Scheduling ensures that Mobile Stations not carrying traffic,need only listen to the Air Interface at pre-determined time intervals. Thisminimizes power consumption.

2.5.1.6 Flow ControlThe Flow Control function raises an alarm at the BSC in the event of a BTSprocessor overload.

2.5.2 Layer 2

The Air Interface Layer 2 functions handle the reliable transmission of speechand data frames between the BTS and Mobile Stations. The protocol used is avariant of LAPD known as LAPDm.

LAPDm transparently transfers complete messages, and handles automaticre -transmission in the event of detected errors.

2.5.3 Layer 1

The Layer 1 functions handle the physical transmission of data over the AirInterface. The Layer 1 functions are:

Modulation/DemodulationThe digital stream of downlink control and traffic data is used to modulatethe RF carrier. The modulated carrier is then transmitted in the GSM RFband. A separate demodulator converts the uplink radio signals receivedfrom the Mobile Stations back to digital form.

Multiframe SchedulingSignalling and traffic data is time interleaved. Each channel uses a singletime slot in successive or periodic TDMA frames.

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3 Transmission Functions


This chapter describes how BTSs are linked to the BSC via the Abis Interface.After introducing the general arrangement, the chapter explains how data ismultiplexed to allow a single Abis Interface to service the full traffic capacity ofup to two, eight-channel BTSs. The chapter includes a list of different optionsfor implementing the Abis Interface at the physical layer.

Clock recovery is outlined, the alternative network configurations, and theGPRS transmission plane are described.

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3.1 Introduction to Transmission FunctionsAll uplink/downlink traffic and control data between the BTS and BSC is carriedon the Abis Interface. This interface is supervised by transmission functions atthe BTS and BSC.

Within the BTS, the transmission functions use the following links to handlethe transfer of traffic and control data between the Abis Interface and theBTS components:

Data

LAPD RSL

LAPD OML.

The following figure shows a simplified block diagram of these interfacesand links.

Abis Interface

BSCBTSLAPD RSL

LAPD OML

Data



BTS Components

Figure 4: BTS-BSC Transmission

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3.2 Multiplexing SchemeEach baseband datastream through the BTS requires a transmission capacityon the Abis Interface of 128 kbit/s for traffic, and 64 kbit/s for signallingpurposes. Additionally the O&M function requires 64 kbit/s.

On the downlink, the BSC transmission functions multiplex the data onto theAbis Interface. At the BTS, the data is demultiplexed by the BTS transmissionfunctions. The transmission functions for a single BTS provide connectionsfor up to two Abis Interfaces. This allows multiple BTSs to be connected toa single BSC using chain or ring configurations.

Uplink data is multiplexed onto the Abis Interface by the BTS transmissionfunctions. The process used is similar to that employed by the BSC for downlinkdata. The mapping between the transmission functions and Abis-links for bothuplink and downlink is programmable.

The following sections describe how the multiplexing allows all BTS - BSCcommunications to be carried on a single Abis Interface. The way in which thebandwidth is utilized is discussed under the following headings:

Abis Interface

Transmission O&M

Signalling

Traffic

Clock

Network Configuration.

3.2.1 Abis Interface

The 2 Mbit/s bandwidth of the Abis Interface is multiplexed to provide 32 timeslots, each of 64 kbit/s. These 32 time slots comprise one CCITT G703/704frame.

Control data on the Abis Interface uses the following Layer 2 protocols atsubmultiplex levels:

LAPD RSL

LAPD OML

Q1.

The first time slot in each frame is reserved for G703/704 management.

3.2.2 Transmission O&M

The TSC regularly polls the BSS transmission equipment, including that atthe BTS. A Q1 service interface is therefore provided on the Abis Interface tocarry data for this function.

The Q1 service interface consists of a 16 kbit/s nibble, which uses part of thefirst 64 kbit/s time slot. Configuration rules exist to ensure that room for the Q1bus is always available, even when a number of BTSs are connected to theAbis Interface - e.g., in a chain or ring configuration. The remaining 31 timeslots in each frame are used as described in the rest of this section.

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3.2.3 Signalling

Signalling frames are sent via the RSL between the BSC and the basebandfunctions, and via the OML between the BSC and the O&M functions. One 64kbit/s time slot is allocated to the OML.

One RSL is required for each BTS carrier. Each RSL can be:

Multiplexed onto a separate 64 kbit/s time slot. This allows up to eight

carriers to be supported.

Static submultiplexed, which combines up to four RSLs onto one 64 kbit/s

time slot. This allows up to 12 carriers to be supported.

For details on GPRS signalling variation refer to Section 3.4 .

3.2.4 Traffic

Time slots not used for signalling information are available to carry traffic. Forthis purpose, each 64 kbit/s time slot is divided into four 16 kbit/s nibbles.

For TCH/F and Enhanced TCH/F, each nibble is dedicated to a single trafficchannel for the duration of a call. Each time slot is shared between four, full-rateTCHs - i.e., between four different calls. Each carrier of the BTS thus requirestwo 64 kbit/s time slots for its full capacity of eight TCH/F, or Enhanced TCH/F.

For TCH/H, each nibble can support two different traffic channels. Each timeslot is therefore shared between eight, half-rate TCHs - i.e., between eightdifferent calls. Each carrier of the BTS can carry sixteen TCH/H by using two64 kbit/s time slots.

For details on GPRS traffic variation refer to Section 3.4 .

3.2.5 Clock

Signals on the Abis Interface are synchronized to the PCM master clock atthe MSC. There is no separate line for the clock, which must therefore berecovered from the signal at each receiver.

3.2.6 Network Configuration

BTSs can be connected to the BSC via star or multidrop (chain or ring)configurations. Star connection is always used for high capacity BTSs whichrequire all or most of the Abis interface bandwidth. Chain or ring architectureenables low-capacity BTSs to share the bandwidth of an Abis connection.

In multidrop configurations, the Abis signal is routed through each BTS, whereit is regenerated before being sent to the next BTS. If the BTS is removed, thevacant Abis connector must be bridged to maintain Abis continuity.

If the BTS is not powered, the routing of the Abis signal is dependent on thetype of BTS in the configuration. In some cases an internal relay connects theinput line to the output line. This passive connection allows the Abis signal tobe routed to the next BTS. For other types of BTS, the Abis connector must beunplugged and bridged as though the BTS had been removed.

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3.3 Abis Interface Physical ConnectionFor indoor BTS, the BTS and BSC multiplexing equipment is normallyconnected using dedicated cabling.

Other methods of Abis Interface connection can be used for outdoor BTS,where the installation of dedicated cabling is not possible. In this case, controlof the transmission medium is in the hands of a third party.

Examples of this type of connection include:

Microwave LinkUsed where a line-of-sight radio path is available.

Leased Line (copper cable or fibre optic)Used where no line-of-sight link is available, or, where the distance betweenthe BSC and BTS is too great for microwave.

3.4 GPRS Transmission PlaneThe GPRS transmission plane consists of a layered protocol structure.

This structure provides user information transfer, along with associatedinformation transfer control procedures such as; flow control, error detection,error correction, and error recovery.

The independence of the transmission plane from the underlying air interface ispreserved via the Gb.

The signalling plane consists of protocols for control and support of thetransmission plane functions for controlling:

GPRS network access connections, such as attaching/detaching fromthe GPRS network.

Attributes of an established network access connection, such as activation

of a PDP address.

The routing path of an establish network access connection, in order to

support user mobility.

Assignment of network resources to meet changing user demands andproviding supplementary services.

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The following figure shows the functional layout of the protocol layer. This layeris composed of the following elements, in relation to the BTS.

Relay, relays the RLC PDUs between the L1 Ater and Um interfaces

L1-RSL; the physical layer between the BSC and the BTS using 64 or16 kbits/s channels

L2-RSL; a LAPD protocol between the BSC the BTS.

For user data traffic and CCCH signalling when the GPRS is present, the BSCis transparent and lines are replaced with GCH lines as follows:

L1-GCH - the physical layer between the 9135 MFS and BTS which usesthe synchronous mode of transmission.

L2-GCH - a simple proprietary protocol between the 9135 MFS and the

BTS for synchronization and channel activation.

SNDCP

GMM/SM

LLC

RRM

RLCMAC

GSM RF GSM RFL2−GCH

L1−GCH

MSTS BTS

RR BSSGP

L2−RSL L2−GSL

L1−RSL L1−GSL

BSC

Abis Ater

L2−RSL

L1−RSL

L2−GSL

L1−GSL

BSSGP

RRM

RLCMAC

BSSGP

NS

L2−GCH

L1−GCH FR

Abis/Ater A935 MFSto SGSN

Figure 5: GPRS Transmission and Signalling Planes

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4 Telecommunication Functions - Baseband


This chapter describes the baseband telecommunications functions. These aredivided into the following categories:

Baseband Processing functions

Call Management functions

Supervisory and Control functions.

The chapter breaks down each category into individual functions, andexplains how these work together to prepare the downlink baseband data fortransmission over the Air Interface. The chapter also explains how the processis reversed for uplink data.

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4.1 Introduction to Telecommunication Functions - BasebandThe baseband telecommunication functions adapt the downlink terrestrialbitstream to the format required for transmission over the Air Interface. Onthe uplink, the process is reversed.

There are three categories of baseband telecommunication function which aredescribed in the following sections.

4.2 Baseband ProcessingBaseband processing consists of:

Speech Transcoding

Rate Adaptation

Channel Encoding and Decoding

Interleaving/De-interleaving

Encryption/Decryption

Demodulation.

These functions are shown in the following figure and are described below.

Encryption

RF Functions

Downlink Direction

Terrestrial Traffic

Decryption

Interleaving

Uplink Direction *

Baseband Functions

Duplexing

RF Transmission

RF Reception

De−modulation

De−interleaving

Channel Decoding

Speech Transcoding

Rate Adaptation

Transmission and Transcoder Functions

To/From MSC

Speech Transcoding

Rate Adaptation

Channel Encoding

Figure 6: Baseband Telecommunication Functions

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4.2.1 Speech Transcoding

Transcoder functions are logically assigned to the BTS. The Transcoder isphysically located between the MSC and the BSC. It is connected to theBTS, via the BSC using the Abis Interface. The Transcoder performs speechtranscoding and rate adaptation on the TCHs in both downlink and uplinkdirections.

Speech transcoding is performed on speech traffic only. The process canbe described in terms of:

Speech Traffic

Correspondence between Traffic and Channel Types

Bit-reordering.

4.2.1.1 Speech TrafficFor downlink speech traffic, two separate processes are carried out on full-rate,enhanced full-rate, and half-rate speech. These processes are, two-stagespeech transcoding, and bit-reordering. The bitstream is then passed to theChannel Encoding function as a sequence of blocks.

The speech transcoding process is shown in the following figure.

64 kbit/s

GSM rec. 04.21GSM rec. 08.60

Abis Channel

RAS is a GSM−specified rate adaptation

RAS

Encoding Function

8 kbit/s 16 kbit/sChannel

EncodingSpeech Transcoding

Transcoder Function

6.5 kbit/s 12.2 kbit/s13 kbit/s

GSM rec. 06.10 TCH/FGSM rec. 06.20 TCH/HGSM rec. 06.60 Enhanced TCH/F

Figure 7: Speech Transcoding for Speech Traffic

4.2.1.2 Correspondence Between Traffic and Channel TypesThe following table shows the relationship between the Speech Traffic Type,the Air Interface Rate and the possible channel types. The table applies toTCH/F, Enhanced TCH/F and TCH/H channel types.

Speech Traffic Type Air Interface Rate (kbit/s) Possible Channel Types *

Full-rate Speech 13 TCH/F Speech

Enhanced Full-rate Speech 12.2 Enhanced TCH/F Speech

Half-rate Speech 6.5 TCH/H Speech

Table 4: Correspondence Table of Speech Transcoding

* TCH/H and Enhanced TCH/F channels are not supported in some versions ofthe BSS.

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4.2.1.3 Bit-reorderingIn addition to speech transcoding, another process is performed on speechtraffic. This is the process of bit-reordering. Bit-reordering is necessary becauseindividual bits in the encoded speech can make an unequal contribution to thesubjective speech quality. Reordering enables bits to be given the protection ofparity and/or convolutional encoding, according to their importance.

Bit-reordering can be performed by the Transcoder or the baseband functions.The remote location of the Transcoder introduces an overhead in transmissiontime via the Abis link. This increases the importance of minimizing speechcoding and decoding delays.

To minimize delays, speech bit-reordering is carried out by the basebandfunctions. This enables the Transcoder to start sending partly coded data onthe downlink, before finishing the coding of a speech frame. Bit-reorderingcan therefore start in the BTS without waiting for the Transcoder to finishprocessing the complete frame.

On the uplink, the processes of speech transcoding and bit-reordering areeffectively reversed. This recovers the original bitstream from the MobileStation’s transmission.

4.2.2 Rate Adaptation

The rate adaptation function adapts the Transcoder data rate to the speechframe format used on the Air Interface. Rate adaptation is performed ondata traffic only.

Rate adaptation is the process of modifying the bitstream and changing thedata rate between the Transcoder and the Air Interface (or vice-versa). Thismechanism forms an essential part of the Layer 1 interface between the twodifferent baseband coding schemes used by the Air Interface and the terrestriallink. Rate adaptation is applied only to TCHs carrying data.

The responsibilities for carrying out rate adaptation are shared between thebaseband functions and the Transcoder.

The process of rate adaptation can be described in terms of:

Data Traffic

Correspondence between data rates.

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4.2.2.1 Data TrafficIn the downlink direction, V.110 data frames received by the Transcoder areadapted in a three-stage process to one of three possible Air Interface rates.

The data traffic rate adaptation process is shown in the following figure.

64 kbit/s

GSM rec. 08.60GSM rec. 04.21 GSM rec. 08.54

RA2, RAA and RA1/RA1’ are GSM−specified rate adaptations

RA1/RA1’

RA2

GSM rec. 04.21

16 kbit/s

Encoding Function

RAARAAChannel

Encoding

Transcoder Function

16 kbit/s8 kbit/s

3.6 kbit/s6 kbit/s12 kbit/s

Figure 8: Rate Adaptation for Data Traffic

The Air Interface uses the lowest rate compatible with the current user datarate. This arrangement allows the maximum level of redundancy to beintroduced into the bitstream.

For TCH/F and Enhanced TCH/F, the Air Interface rates of 12, 6 or 3.6 kbit/ssupport user data rates of:

9600 bit/s

4800 bit/s

2400 bit/s

1200 bit/s

600 bit/s

300 bit/s.

User rates below 2400 bit/s are rate-adapted to 2400 bits/s by simple bitrepetition. As a result, the Encoder has only to support three user data rates:9.6, 4.8 or 2.4 kbit/s.

Rate adaptation in the uplink direction is essentially a reverse of processingcarried out on data traffic for the downlink.

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4.2.2.2 Correspondence Between Data RatesThe following table shows the relationship between the User Data Rate, theIntermediate Data Rate, the Air Interface Rate and the possible channel types.The table applies to TCH/F and Enhanced TCH/F.

User Data Rate(bit/s)

Intermediate DataRate (kbit/s)

Air Interface Rate(kbit/s) Possible Channel Types *

300 8 3.6 TCH/F2.4 or Enhanced TCH/F2.4




4800 8 6 TCH/F4.8 or Enhanced TCH/F4.8

9600 16 12 TCH/F9.6 or Enhanced TCH/F9.6

Table 5: Correspondence Table of Rate Adaptation

* Enhanced TCH/F channels are not supported in some versions of the BSS.

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4.2.3 Channel Encoding and Decoding

These two functions are very similar in the way they process information.Channel Decoding is essentially the reverse of Channel Encoding.

4.2.3.1 Channel EncodingChannel Encoding is the baseband processing implemented by the channelencoding algorithm, as defined in GSM rec. 05.03, version 5.2.0 or later.

Data for Channel Encoding is received from the Rate Adaptation function(speech and data traffic), and from the upper OSI layers (data for signallingchannels). From these inputs, the Channel Encoding function produces a stringof encoded TDMA bursts for transmission over the Air Interface. The resultingbursts can also carry information for internal BTS control and test purposes.

Channel Encoding is achieved using a combination of convolutional and blockencoding. Convolutional encoding produces a greater number of output bitsthan there are input bits. Applying convolutional encoding to reorderedspeech bits enables the most important bits to be given the protection of ahigh level of redundancy.

Four types of bursts are encoded:

Normal Burst (encoded) which is used on the traffic and signalling channels

Synchronization Burst (encoded) which is used on the SCH

Frequency Correction Burst (fixed pattern) which is used on the FCCH

Dummy Burst (fixed pattern) which is used for empty BCCH time slots andunused TCH time slots.

4.2.3.2 Channel DecodingThe Channel Decoding function processes uplink information. ChannelDecoding is left largely to the system manufacturer, but is essentially thereverse of encoding.

A BTS configured for antenna diversity provides two receive paths, allowinguplink signals from two separate antennas to be processed. Each incomingtime slot has two uplink signals which are combined in the Channel Decoder.

For traffic and signalling received in the uplink, Channel Decoding is appliedafter demodulation and de-interleaving. Channel Decoding is essentially thereverse of Channel Encoding. It produces a GSM-compliant bitstream ready forRate Adaptation and onward routing to the terrestrial path. This is done by acombination of convolutional and block decoding.

Convolutional decoding is performed on all received channel types, and isachieved by applying the Viterbi algorithm.

Block decoding is applied to Control Channels and TCH, both full and half-rate.It uses a dedicated routine defined in GSM rec. 05.03 for Channel Decoding.

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4.2.4 Interleaving/De-interleaving

Interleaving is applied to the channel-encoded sub-blocks, to improve the errordetection rate. The baseband telecommunications functions are responsiblefor interleaving data for the downlink, and for de-interleaving data receivedon the uplink.

The interleaving process can be divided into three processes:

Sub-block partitioning

Inter-block interleaving

Intra-burst interleaving.

All the logical channels follow this scheme, except that bursts carried by theBCCH are not interleaved.

4.2.4.1 Sub-block PartitioningThe first stage in the interleaving process is to split the encoded bits of aspeech or data channel into sub-blocks. These can be partitioned into furthersub-blocks depending on the type of channel. Sub-blocks are then transmittedwithin the TDMA frame structure as defined by the inter-block interleavingscheme, summarized below.

4.2.4.2 Inter-block InterleavingInterleaving of the sub-blocks is diagonal for TCH and FACCH, or rectangularfor signalling channels. The effect of these two types of interleaving is to enableblocks to be mapped onto bursts according to the channel type.

4.2.4.3 Intra-burst InterleavingIntra-burst interleaving is achieved by distributing the interleaved sub-blocksover a number of bursts.

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4.2.5 Encryption/Decryption

Encryption and Decryption are optional security functions that protect theconfidentiality of messages sent over the Air Interface. When Encryptionis used, the baseband functions carry out Encryption and Decryption ontraffic channels and dedicated control channels. Common channels must betransmitted without Encryption. This is because a cipher key is dedicated toeach individual call, and this key is not known to the Mobile Station until theinitial stages of call establishment are underway.

Three processes are used for message confidentiality:

Encryption

Decryption

TDMA multiframe building.

4.2.5.1 EncryptionEncryption is implemented using the confidential A5 algorithm, specified inaccordance with GSM rec. 03.20. Three versions of this algorithm are used:

A5/1 which performs the most secure level of Encryption

A5/2 which performs a level of encryption effective for normal use, but which

is less secure than that provided by A5/1

A5/0 which performs no Encryption.

The implementation of the A5 algorithm is hardware dependent. For BTSs thatsupport dual-rate channels, the A5/1 and A5/2 cipher key must be downloadedto the BTS, from the BSC, before Encryption can start.

For other non dual-rate BTSs, the cipher key is held in EPROM in the BTShardware. There are three different hardware types, with the EPROMcontaining either the A5/1, A5/2, or A5/0 algorithm.

4.2.5.2 DecryptionDecryption uses the same algorithms as those used for Encryption. Decryptionis the reverse of Encryption.

4.2.5.3 TDMA Multiframe BuildingOn the downlink, the encrypted bursts are finally multiplexed to build the TDMAmultiframes, before being sent to the RF telecommunications functions.

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4.2.6 Demodulation

Demodulation recovers the baseband data contained in the radio signalreceived in the uplink direction.

The RF telecommunication functions remove the RF carrier and producecomplex samples of the digital baseband. These samples are sent to thebaseband functions, where the GMSK demodulation is performed. At thisstage, the Demodulation function applies frequency correction to compensatefor frequency drift at the Mobile Station.

In addition a number of measurements are made on the uplink signal to provideinformation required by the BSC for control purposes:

Signal-to-Noise Ratio

Adaptive Frame Alignment

Soft Decision Bits.

4.2.6.1 Signal-to-Noise RatioSNR measurements are made by the Demodulation function as part of thesignal processing. The resulting values are also used by the BSC to optimizechannel allocation.

4.2.6.2 Adaptive Frame AlignmentTOA estimation measures the propagation delay over the Air Interface, asMobile Station to BTS distances change.

Using TOA measurements, the BTS calculates timing advance changes foreach Mobile Station. This is done by measuring the time offset between its ownburst transmission and the reception of Mobile Station bursts.

The timing advance data is sent on the SACCH to the Mobile Station. TheMobile Station then advances its burst transmissions relative to the bursts itreceives from the BTS. Two such updates per second enable the Mobile Stationto keep its burst transmissions synchronized to the allotted time slots. Theoverall process is known as Adaptive Frame Alignment.

When an Mobile Station is switched on or otherwise enters a service area, theTOA is initially estimated using the Random Access burst. The BTS measuresthe position of the received burst within the Burst Period and its Guard Period.

4.2.6.3 Soft Decision BitsThe Viterbi algorithm is used within the Decoder function. It requires theinformation produced by Demodulation of a burst to be supplied in a formatknown as soft decision bits. The demodulated bursts are therefore output inthe form of soft decision samples.

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4.3 Call Management FunctionsThe baseband telecommunications functions participate in a number of CallManagement functions:

Radio Link Recovery

Radio Resource Indication

Paging

DTX

DRX

Quality Measurement

Power Control.

4.3.1 Radio Link Recovery

The Radio Channel Management function detects the need for radio linkrecovery when communication with an Mobile Station is lost. Radio linkrecovery consists of maximizing the transmitter power at the BTS and MobileStation. If the recovery procedure fails, this is recognized by the BSC as a radiolink failure. The situation can then be handled by the network in an orderlymanner. This mechanism is based on signal strength values and qualityparameters provided by the baseband telecommunication functions.

4.3.2 Radio Resource Indication

The quality of a radio channel can change very quickly, due to the movement ofthe Mobile Stations. For this reason, the best channel currently available cannotbe predicted for more than a few seconds. To ensure that channels are allocatedin the most effective manner at a given moment, idle channels are continuouslymonitored by the BTS. The measurements on which this mechanism is basedare performed by the baseband telecommunication functions.

4.3.3 Paging

The Paging function is used to find an MS. For this purpose the BSC firstdetermines the Paging Group to be used. This is based on the InternationalMobile Subscriber Identity, or Temporary Mobile Subscriber Identity, of theMobile Station to be paged. The Paging Group value is then sent to the BTSwith a paging request message.

The baseband telecommunication functions do this by using the Paging Groupinformation to construct PCH messages.

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4.3.4 Discontinuous Transmission

DTX is an option in accordance with GSM rec. 06.31. It is designed to reduceco-channel interference between cells, and to cut power consumption in theMobile Stations.

On the downlink TCH, a VAD algorithm in the Transcoder analyzes inputspeech. If more than four successive speech frames are detected withoutspeech activity, the Transcoder can perform DTX.

If DTX is performed, it is controlled by the BSC. During DTX, a SID frame issent to the Mobile Station at the start of every speech inactivity period. FurtherSID frames are sent at 480 ms intervals thereafter, for as long as the inactivityperiod lasts. This compares with 20 ms intervals between normal speechframes, so the number of bursts transmitted is greatly reduced. This patternis modified by constraints to ensure that DTX does not prevent valid signalmeasurements being made in the BTS.

During a silent period the frame level functions encode dummy bursts for thetransmitter. This stops TCH radio transmission when there is no useful traffic totransmit. However, DTX is overridden when FACCH data needs to be sent.

DTX is not applied to TCHs transmitted by the BCCH transmitter, since GSMprotocol requires continuous BCCH transmission. In this case, a dummy burstis transmitted when the FDMA time slot is on the BCCH frequency. The BTSapplies the transmitter power value of the BCCH carrier to the transmitteddummy burst.

The SID frames tell the Mobile Station when to listen to the TCH. They alsoenable the Mobile Station to generate ’comfort noise’ during the silence periods.This prevent the caller from thinking that the call has been disconnected.

DTX can be used on both uplink and downlink. If it is used on the uplink, theChannel Decoder distinguishes between speech frames and SIDs on thebasis of the frame content. The Channel Decoder uses SID flags to controlthe speech decoding.

4.3.5 Discontinuous Reception

The BTS supports the GSM option of DRX by Mobile Stations. When DRXis used, the downlink CCCH is divided into a number of PCH sub-channels.This allows all paging messages for a particular Mobile Station to be sent onthe same sub-channel. Each Mobile Station can determine this channel frominformation sent on the CCCH. When idle, the Mobile Station needs listenonly to the relevant sub-channel. Since this contains only a small sub -set ofall the PCH frames, the technique results in a significant saving in powerconsumption by the Mobile Station.

When DRX is used, the telecommunication functions continue to receive signalstrength measurements from the Mobile Stations. These measurements aremade by the Mobile Station during the associated paging block duration.

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4.3.6 Quality Measurement

To exercise Power Control and Handover functions, the BSC uses informationabout the signal quality and received signal strength for all channels. Bothuplink and downlink channels are monitored for this purpose. This function issupported by the BTS in accordance with GSM rec. 05.08.

For a given channel, the RF functions measure the received signal strengthon the uplink. These are sent to the baseband functions every TDMA frame.Here, the Channel Decoder constructs the received signal quality for everyblock, then averages the values. These values are utilized by the PowerControl and Handover functions.

4.3.7 Power Control

The RF power radiated by Mobile Stations and the BTS is controlled by theBSC. This minimizes co-channel interference and conserves battery powerat the Mobile Station. On the uplink, the BTS measures the signal strengthand signal quality received from the Mobile Station as previously described.For the downlink, the BTS acquires the equivalent values from the MobileStation via the SACCH.

These measurements are processed by the BSC, which sends power controlvalues to the BTS via Layer 3. The Channel Encoding function routes this datato the RF telecommunications functions or Mobile Station.

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4.4 Supervisory and Control FunctionsThe Supervisory and Control functions consist of:

Clock Distribution

Protocol Management

Radio Channel Management

Transcoder Time Alignment.

4.4.1 Clock Distribution

The Clock Distribution function distributes all clocks required by the basebandfunctions. Clocks are derived from the Timing Generation function.

4.4.2 Protocol Management

In order to carry out its telecommunications and O&M functions, the basebandtelecommunications function manages protocols corresponding to OSILayers 1, 2 and 3. For each layer it is possible to find more than one protocol -for example, there are three Layer 2 protocols: LAPD, LAPDm, and the BTSinternal links.

4.4.3 Radio Channel Management

Radio Channel Management is based on decisions made by the BSC. Thesedecisions are implemented within the BTS, which effectively reacts to BSCcommands. This arrangement requires a constant exchange of signallingmessages between the BSC and the Mobile Station. These messages arehandled using the GSM rec. 08.58 and 04.08 protocols.

Within this mechanism, the baseband function is responsible for routingtransparent messages, and for processing non-transparent messages beforerouting them. These activities are handled by the baseband Layer 3 functions,which play a key role in managing the Air Interface and its channels.

The measurements are preprocessed in the BTS and sent via Layer 3 to theBSC. Radio channels can then be reallocated by the BSC depending on thecurrent measurement results. Radio Channel Management is required forboth dedicated channels and CCCH.

For GPRS systems channel management is carried out from the 9135 MFS viathe master PDCH.

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4.4.4 Transcoder Time Alignment

The multiframe organization of TCHs dictates that speech blocks for the AirInterface can start only at predefined points in time. Since each speech blockcorresponds to 20 ms of speech, an asynchronous entity in the downlinkspeech path can lead to a delay of up to 20 ms.

To avoid this difficulty, the Transcoder is told the precise points in time to sendTRAU frames to the BTS. This function, known as Transcoder Time Alignment,is implemented by the telecommunication functions in accordance with GSMrecommendations:

08.60 for TCH/F and Enhanced TCH/F

08.61 for TCH/H.

The baseband functions measure the shift between the ideal point in time toreceive a frame from the Transcoder, and the actual time of arrival. Thisinvolves measuring the delay between reception of the TRAU frames and theencoding of a speech block. The resulting value is sent by the BTS to theTranscoder, which adjusts its schedule accordingly.

For each datastream, the baseband functions provide control and basebanddata processing for the eight time slots that comprise one TDMA frame.

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5 Telecommunication Functions - RF


This chapter describes the RF telecommunication functions. Following a briefintroduction, the chapter discusses RF functions under the headings:

RF processing

Control functions

Coupling functions.

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5.1 Introduction to Telecommunication Functions - RFThe RF telecommunication functions convert downlink databursts into amodulated RF carrier, for transmission over the Air Interface.

On the uplink, the functions receive incoming GSM radio signals from theAir Interface. They then convert them into samples suitable for basebandprocessing.

The RF Telecommunication functions are described in three categories:

RF processing

Control functions

Coupling functions.

The following figure shows these functions for BTSs with frequency hoppingusing constant carrier frequencies.

PowerAmplification

Control

Downlink Direction

Uplink Direction

RF Functions Baseband Functions

Coupling

Down− conversion

Signal Amplification

A−D Conversion

Digital Pre−processing

* Antenna Diversity − some uplink functions are duplicated for Antenna Diversity.

* Frequency Generator

Frequency Generator

Frequency Hopping

Power Coupling and Detection

GMSK Modulation

Up−conversion

Frequency Generator

Baseband Downlink Processing

Baseband Uplink Processing

Figure 9: RF Telecommunication Functions for BTSs with Frequency Hopping using Constant CarrierFrequencies

For BTSs using constant carrier frequencies, frequency hopping is achieved byswitching successive TCH time slots between different transmitters. Refer toSection Frequency Hopping (Section 5.2.2) for more information.

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The following figure shows these functions for BTSs with frequency hoppingusing programmable carrier frequencies.

Control

Downlink Direction

Uplink Direction

RF Functions Baseband Functions

Coupling

* Antenna Diversity − some uplink functions are duplicated for Antenna Diversity.

*

Power Coupling and Detection

Power Amplification

Up−conversion

GMSK Modulation

Baseband Downlink Processing

Baseband Uplink Processing

Frequency Hopping

Digital Pre−processing

A−D Conversion


Down− conversion

Frequency Generator

Frequency Generator

Frequency Generator

Figure 10: RF Telecommunication Functions for BTSs with Frequency Hopping using Programmable CarrierFrequencies

For BTSs using programmable carrier frequencies, frequency hopping isachieved by controlling the transmitter and receiver frequency generators. Thegenerators are programmed to a different frequency for successive TCH timeslots. Refer to Section Frequency Hopping (Section 5.2.2) for more information.

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5.2 RF ProcessingRF processing consists of the following functions:

RF Carrier Generation

Frequency Hopping

GMSK Modulation and Up-conversion

Power Amplification and Power Control

Channel Selection and Conversion


A-D Conversion

Digital Pre-processing

5.2.1 RF Carrier Generation

A BTS can be configured for up to eight discrete RF carriers. Each carriersupports up to eight full-rate or 16 half-rate GSM channels. Depending on thehardware configuration, each RF carrier is generated:

At constant frequency - each transmitter sends successive time slots on a

constant carrier frequency. This is produced by a frequency synthesizer.

At a programmed frequency - the synthesizer is reprogrammed for eachtime slot.

In both cases, the BCCH is transmitted at a constant frequency. Where afrequency synthesizer is used, it is reprogrammed at a constant frequency forsuccessive BCCH time slots.

5.2.2 Frequency Hopping

Frequency hopping is the optional process of transmitting successive time slotsof a GSM channel, on different carrier frequencies. The carrier frequency isspecified by the ARFCN, under control of the FHA.

Frequency hopping reduces the effects of multipath distortion and co-channelinterference between cells. It is applied only to the TCHs and SDCCH, sincethe BCCH must be transmitted on a constant carrier frequency.

Frequency Hopping is performed on traffic transmitted over the Air Interface.The process is described for the:

Downlink direction

Uplink direction.

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5.2.2.1 Downlink DirectionWhen frequency hopping is in use, traffic that is to be transmitted to MobileStations is frequency hopped. The way a BTS processes the TCHs andSDCCH varies depending how the hardware is used.

The BTS transmitters are tuned by frequency synthesizers. These synthesizerscan be programmed to produce different frequencies or they can be set to aconstant frequency.

The frequency synthesizer operation determines how the BTS processesthe traffic that is to be transmitted:

Constant carrier frequencyFrequency hopping is achieved by switching successive TCH time slotsbetween different transmitters. When frequency hopping is switched off,each datastream remains connected to the same transmitter. The BCCH isalways connected to a single, dedicated transmitter.

Programmable carrier frequencyFrequency hopping is achieved by programming the synthesizers toa different frequency for successive TCH time slots. When frequencyhopping is switched off, the TCH frequency synthesizers are repeatedlyre-programmed for the same ARFCN. The BCCH synthesizer is programmedonly once, during power up or following a change in the ARFCN.

5.2.2.2 Uplink DirectionWhen frequency hopping is in use, traffic from Mobile Stations is frequencyhopped. The way a BTS processes received frequency hopped TCHs variesdepending how the hardware is used.

The BTS receivers are tuned by frequency synthesizers. These synthesizerscan be programmed to produce different frequencies or they can be set to aconstant frequency.

The frequency synthesizer operation determines how the BTS processesthe received TCH:

Programmable frequency synthesizerA receiver with a programmable frequency synthesizer is retuned, undercontrol of the FHA, for each time slot. Each receiver therefore preserves theoriginal TDMA frame content, and with it the cyclic data that comprises theassociated TCHs. This type of receiver provides a contiguous datastream,which can be passed directly to the telecommunications baseband functions.

Frequency synthesizer set to a constant frequencyA receiver tuned by a frequency synthesizer set to produce a constantfrequency, receives uplink signals on a single frequency. Successive,frequency hopped, bursts sent by a single Mobile Station are thereforereceived by different receivers. To enable the telecommunications basebandfunctions to process the uplink TCHs, the received bursts are switched,under control of the FHA, to remotely reassemble the original TDMA frames.

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5.2.3 GMSK Modulation and Up-conversion

Downlink data is received by the RF telecom functions in the form of encodedbursts. The GMSK Modulation function converts the downlink data into twobaseband signals I and Q. The data is then differentially encoded, and digitalvalues are generated from a sine and cosine look-up table. The digital valuesare converted to analog signals, amplified and filtered, to form the basebandsignals I and Q.

The I and Q signals are used to modulate the RF carrier. The downlink signal isthen ready for amplification.

5.2.4 Power Amplification and Power Control

Power Amplification boosts the RF signal in several stages to the requiredoutput power. Output power for each transmitter is constantly monitored,and set to a level specified for each time slot. The power level is controlledby the Power Step parameter, which is included in the downlink signallingfrom the BSC.

The TCH carrier output power can vary dynamically for each burst, and isramped up or down as necessary. The BCCH carrier output power remainsat a constant level, but is nevertheless controlled by the Power Step for eachdiscrete time slot.

Power Amplification is temperature limited. If the temperature of the RF powerstage exceeds a pre-defined limit, the RF output power is switched OFF and analarm is sent to the O&M function.

The Power Step parameter also controls the PA switches. These enable/disablethe PA output power for the TCH and BCCH carriers.

During normal operation, each carrier is enabled for the active period of eachtime slot. This leaves a guard period between time slots, during which nocarrier is transmitted.

During startup, the TCH and BCCH carriers can be suppressed for individualtime slots. The same suppression is applied while alarms are in force, orduring unused time slots.

5.2.5 Channel Selection and Conversion

A BTS can be configured with up to eight receivers, depending on the type ofhardware used. Each receiver can process up to eight full-rate or 16 half-rateGSM channels.

Incoming signals are received via the antenna and coupling functions. Thereceivers can be configured for diversity or non-diversity reception.

Each receiver is tuned by a frequency synthesizer. This is either set to producea constant frequency output or is programmable. The method used dependson the BTS hardware. When the synthesizer is programmable, it re-tunes thereceiver to the channel frequency for each discrete time slot.

The incoming GMSK modulated RF signal is filtered to suppress interferencefrom outside the selected frequency. The RF signal is then mixed with thefrequency oscillator/synthesizer signal. This down-converts the required signalinto an intermediate frequency. The channel number is selected by an O&Mcommand which is sent to the control function of the transmitter.

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5.2.6 Signal Amplification

The receiver filters and amplifies the intermediate frequency signal. This signalis then split into two paths, high and low gain. Using a second local oscillatorsignal, I/Q demodulators down-convert the high and low gain intermediatefrequency signals to baseband I and Q components. These are ready forA-D conversion.

5.2.7 A-D Conversion

The receiver A-D converts the high and low gain I and Q signals into a digitalrepresentation. Either the high gain or the low gain path is selected, dependingon signal strength. This increases the dynamic range of the receiver.

5.2.8 Digital Pre-processing

The receiver carries out the following Digital Pre-processing procedures:

DC offset correction to negate the influence of DC variations in the signal

Power calculation to select one of the two signal paths for further processing;this depends on the power of the received signal

Frequency translation which supports the demodulation process.

The data is then output to the telecommunications baseband functions fordemodulation.

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5.3 Control FunctionsThe principal control functions are:

RF Hardware Status

Frequency Hopping Control

Clock Management

Frequency Synthesizer Programming

Alarm Processing

High/Low Gain Selection.

5.3.1 RF Hardware Status

The status of the RF hardware is dynamically configured to meet the currentrequirements of the BSS. The control functions therefore manage the RFhardware according to the changing requirements during:

Power-up and initialization

Normal operation

Reconfiguration

Failure conditions.

5.3.2 Frequency Hopping Control

Control of the frequency hopping function is performed for hardwareconfigurations that implement frequency hopping as part of the RF functions.

5.3.3 Clock Management

Clock selection and supervision is performed for hardware configurationsthat provide redundant clock buses.

5.3.4 Frequency Synthesizer Programming

The frequency synthesizers in the BTS are programmed under control of theBSC. This function is implemented by extracting control signals from thedatastream provided by the BSC.

5.3.5 Alarm Processing

Alarms originating in the RF functions are supervised, collected and passed tothe O&M functions.

5.3.6 High/Low Gain Selection

Selection of the high or low gain path on the uplink is determined by measuringthe received signal power on the high and low gain paths. If the signal strengthfor the low gain path is high enough, then it is selected, otherwise the highgain path is used.

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5.4 Coupling FunctionsThe BTS coupling functions interface the RF signal paths to the BTS antenna(s).

The principal coupling functions on the downlink and uplink are:

Isolating (downlink)

Combining (downlink)

Duplexing (optional for downlink and uplink)

Power Coupling and Detection (downlink)

Antenna Pre-amplification (uplink)

Receiver Front-end (uplink).

5.4.1 Isolating

The isolating function prevents the generation of additional intermodulationproducts, by improving the isolation between the transmitters.

5.4.2 Combining

The combining function sums the RF signals from the BTS transmitters, toenable them to share a single antenna. This function is not configured forsingle transmitter BTS.

5.4.3 Duplexing

Duplexing enables the uplink and downlink to share a single antenna.Duplexing performs the following functions that are common to the downlinkand uplink signal paths:

Suppresses unwanted emissions outside the downlink band, especiallyemissions which would fall into the uplink band.

Ensures that isolation between the transmitter and receiver in the duplexing

function prevents the downlink signals from blocking the receiver.

Ensures that wide-band noise and spurious emissions present in thedownlink carrier do not cause interference in the receive band.

On the uplink, duplexing also performs the following additional functions:

Rejects the receiver’s image frequency

Ensures a high degree of isolation from the transmitters.

Duplexing does not deal with the third order intermodulation components of thetransmitter. Channel frequency allocation must therefore ensure that theseintermodulation components do not fall in a used receiver channel.

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5.4.4 Power Coupling and Detection

The Power Coupling and Detection function is not configured in all hardwareconfigurations. The function protects the BTS against the effects of reflectedRF power by measuring the reflected power level. For example, if the RFcoupling to the antenna is interrupted, the power measurement will exceeda specified threshold. The function immediately diverts the RF power to amatched termination.

5.4.5 Antenna Pre-amplification

The Antenna Pre-amplification function is realized in close proximity to theantenna, to ensure optimum signal-to-noise ratio. It provides fault-tolerant,low -noise pre-amplification of the received signal, ahead of the main receiverfunction. The Pre-amplification function also provides an additional level ofco-channel rejection.

The Antenna Pre-amplification function delivers the uplink signal to the BTSreceivers via a Power Splitting function, which can provide an uplink signal toup to eight receivers.

5.4.6 Receiver Front-end

The Receiver Front-end function provides low-noise pre-amplification of thereceived signal, ahead of the main receiver function. The Receiver Front-endfunction also provides an additional level of co-channel rejection.

The Receiver Front-end function delivers the uplink signal to the BTS receiversvia a Power Splitting function. This Power Splitting can provide an uplink signalto up to eight receivers, depending on the hardware in use.

The Receiver Front-end function is realized as part of the main BTS cabinethardware configuration.

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6 O&M and Support Functions


This chapter describes the O&M and the Support functions.

The chapter first describes the O&M functions in detail followed by the detaileddescription of the Support functions.

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6.1 O&M FunctionsThe O&M functions monitor and control the operation of the BTS. Theseresponsibilities are shared with the BSC. The description of these functions isprovided by the following sections:

O&M Connections

O&M Processing

RF Self-test

Recovery Strategy.

6.1.1 O&M Connections

The O&M functions exchange information and command messages withdifferent parts of the BTS, and with the BSC. This allows the O&M functions tomonitor and control the operation of the BTS. The different types of connectionused for this purpose are grouped into:

Internal Connections

External Connections.

6.1.1.1 Internal ConnectionsInternally the O&M functions are connected to all processor controlled BTSfunctions. This is achieved by the internal Layer 2 links which:

Provide high-speed transfer of downloadable software, operationalparameters and alarms to processor controlled functions.

Handle parameter and alarm transfer to all other intelligent functions(including RF functions).

The non-intelligent BTS functions, for example, power supplies, fans, etc., areconnected to the O&M functions via dedicated alarm and control lines.

6.1.1.2 External ConnectionsTwo interfaces provide the external connections shown in the following table.

Interface Description

LAPD OML The O&M function is connected to the BSC via theLAPD OML Interface. This is multiplexed onto theAbis Interface by the BTS transmission functions.

MMI A local MMI is provided for operator control of the BTS.This control is in the form of local maintenance andcontrol operations performed by the O&M functions.The BTS sends a message to the BSC to inform itof the operator’s actions.

Table 6: O&M External Connections - Interfaces

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6.1.2 O&M Processing

O&M processing uses four categories of functions:


Fault Management


External Alarm Handling.

6.1.2.1 Configuration ManagementThe Configuration Management functions handle a number of tasks as shownin the following table.

Task Description

Central Command Control GSM function-level configuration commands from the BSC or operator aretranslated to low-level commands for the relevant BTS submodule(s).

Configuration/ Initialization Software initially downloaded from the BSC to the OMU is subsequentlydownloaded from the OMU to other BTS modules. The O&M functionsconfigure each BTS module, and report start -up test results to the BSC.

Software Replacement This function enables changeover to newly downloaded software to beperformed, while retaining the configuration.

Database A database is maintained for use by other O&M functions and the BSC. Itcontains complete details of the BTS including configuration data, alarmand status information.

Table 7: O&M Configuration Management Tasks

6.1.2.2 Fault ManagementThe Fault Management functions perform a range of tasks as shown in thefollowing table.

Task Description

Testing The Fault Management functions initiate BTS self-tests. These include RFself-tests, dedicated alarm line testing and submodule diagnostic tests.Continuous checks are made on the alarm inputs and, if a change occurs,the database is updated. The BTS sends the test results to the BSC atGSM function level.

Alarm Detection andFiltering

Detects and filters alarms to prevent the generation of multiple fault reportsfrom a single source of failure.

Alarm Forwarding Forwards alarms to the BSC for processing.

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Task Description

Alarm Translation Translates alarms to a GSM function-level format, independent of hardwareand software versions.

Command Translation Translates alarms to a GSM function-level format, independent of hardwareand software versions.

Table 8: O&M Fault Management Tasks

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6.1.2.3 Dedicated Alarm and Control HandlingThe Dedicated Alarm and Control Handling function provides simple controland alarm signalling for non-intelligent BTS submodules. Examples ofnon-intelligent BTS submodules include power supplies, fans, etc. The functionmakes continuous checks on the alarm inputs and updates the database if achange occurs. Alarms are reported on request.

6.1.2.4 External Alarm HandlingExternal Alarm Connections provide a mechanical/electrical interface betweenthe Dedicated Alarm and Control Handling functions, and the BTS externalalarm sources. Examples of BTS external alarm sources include cabinetdoor switches, smoke detectors, etc.

6.1.3 RF Self-test

The optional RF self-test function enables the BTS baseband and radio pathsto be tested. The test is implemented by routing the BTS transmitter output tothe uplink path, in a simple loopback arrangement.

When the test is completed, a report is sent to the O&M functions. This showsthe status of the hardware in the loop, together with key performance figures.

6.1.4 Recovery Strategy

In addition to monitoring and reporting the status of the BTS, the O&M functionscan implement recovery actions. The recovery strategy varies accordingto the type of BTS.

For configurations that include redundant hardware, recovery actions caninclude:

Hardware reconfiguration

Selective hardware shutdown

Hardware reset

Software reload and restart.

For BTSs designed as a simple unit, without redundancy, recovery actions arelimited to restart and reset attempts.

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6.2 Support FunctionsThe principal BTS support functions are described in the following sections:

Internal Power Supplies

Timing Functions

Internal Temperature Control.

6.2.1 Internal Power Supplies

All BTS configurations are equipped with internal power supplies. Theseconvert the mains supply voltage to the DC voltages required by individualBTS modules. Power supply units are available for DC only input and forAC/DC mains input.

Additional features provided are:

Output Monitoring

Battery Backup.

6.2.1.1 Output MonitoringAll power supply outputs are monitored for output voltage. If an overvoltageor undervoltage condition is detected, an alarm is raised and sent to theO&M functions.

6.2.1.2 Battery BackupOptional backup batteries maintain operation in the event of mains supplyfailure. Backup batteries can be permanently connected in-circuit, or switchedautomatically when needed.

6.2.2 Timing Functions

The Timing functions are:

Master frequency generation

Timing signal generation

Clock distribution.

6.2.2.1 Master Frequency GenerationAll BTS clocks are derived from a 13 MHz master reference frequency. Themaster frequency is generated in the master frequency generator. This is ahigh stability oscillator. It can operate in free-running mode, or synchronizedmode to the PCM clock on the Abis Interface.

Most BTS configurations can be run in slave mode. In this arrangement, theBTS is synchronized as slave to the master clock of another BTS.

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6.2.2.2 Timing Signal GenerationFrom the 13 MHz reference signal, the following slower synchronization clocksare derived by a process of frequency division:

2.16 MHz OBCLK

216.7 Hz FCLK

38.4 kBaud FN

1.733 kHz TSCLK.

6.2.2.3 Clock DistributionThe Clock Distribution function distributes the synchronization clocks as follows:

TSCLK, OBCLK, FCLK and FN to the Baseband Telecommunicationfunctions

OBCLK, FCLK and 13 MHz reference signal to the RF Telecommunication

functions.

6.2.3 Internal Temperature Control

With the exception of hardware types that are hermetically sealed, all BTSsare equipped with an internal temperature control function. This consistsof heating elements and cooling fans, controlled by temperature sensorsand supervisory equipment.

Depending on the hardware configuration, the Temperature Control functioncan delay power-up of the main equipment at switch-on. Power is applied whenthe internal temperature has been raised or lowered to within specified limits.

The Temperature Control function monitors the internal temperature duringBTS operation. It switches the fans or heaters on and off, to maintain thespecified temperature range.

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7 BTS Functional Architecture


This chapter describes how the primary functions of a G1/G2 BTS are mappedonto a functional architecture.

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7.1 Introduction to BTS Functional ArchitectureThe hardware required to implement the functions of the functional blocksdepend on the hardware variants and the functional units architecture.

There are two hardware variants; G1 BTS Mark2 and G2 BTS. One type offunctional unit architecture exists, G1/G2 BTS architecture.

7.2 G1/G2 BTS ArchitectureThe G1 BTS Mark2 and the G2 BTS have the same functional architecture.

The G1 BTS Mark2 covers only GSM 900, the G2 BTS covers GSM 900and GSM 1800.

7.2.1 Functional Units

The G1/G2 BTS contains the following functional units:

BIE

Frame Unit

Station Unit

Carrier Unit

Coupling Unit.

Each functional unit can use a number of different submodule types, dependingupon hardware variant and BTS configuration.

The BIE is not described in an individual section, it is included in the Frame Unitdescription and is also mentioned in the Station Unit description.

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7.2.2 Functional Block Diagram

The functional units and their interfaces are shown in the following figure.

Frame UnitStation UnitCarrier UnitCoupling Unit

Mobile Stations

Antennae

DCL2

DCL1

BSI

BSI

BSI

FHI

FHI

Clocks

Clocks

FHI

FHI

Clocks

Clocks

MMI

RF

RF BIE

Coupling Unit

Carrier Unit 1

Carrier Unit n *

BTS Terminal

Station Unit

Frame Unit n *

Frame Unit 1

Base Station Controller

Air Interface

Transmission Interface Equipment

* n <= 8

* n <= 8

Figure 11: G1/G2 BTS Functional Units Breakdown

7.2.3 Interfaces

The following table describes the interfaces shown in the previous figure.


DCL1 Connects the FU to the OMU. DCL1 provides high-speed transfer ofdownloaded software, operational parameters and alarms.

DCL2 (V.11 Q1) Connects the OMU to all other intelligent equipment. This equipment(for example, CUs) requires only the transfer of parameters and alarmsignals.

Clock links Provides the clock distribution.

FHI Provides internal data transfer.

BSI Provides external communication with the BSC via the BIE.

MMI Provides control via a local BTS Terminal.

Table 9: Principal G1/G2 BTS Interfaces

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7.3 Mapping of Functional Blocks to Functional UnitsThe BTS functional blocks are mapped onto the G1/G2 BTS functional units asshown in the following tables:

Table 10 - Transmission

Table 11 - Telecommunication Baseband

Table 12 - Telecommunication RF

Table 13 - O&M

Table 14 - Support.

7.3.1 Transmission

Functional Block G1 BTS G2 BTS

Multiplexing Nokia * SMBI *

Transmission of Signalling Nokia * SMBI *

Transmission of O&M Data Nokia * SMBI *

Transmission of Traffic Nokia * SMBI *

Clock Synchronization Nokia * SMBI *

Table 10: Functional Block to Functional Unit Mapping - Transmission

* These functional units are not described in this document.

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7.3.2 Telecommunication Baseband

Functional Block G1/G2 BTS

Rate Adaptation Frame Unit

Channel Encoding and Decoding Frame Unit

Interleaving/De-interleaving Frame Unit

Encryption/Decryption Frame Unit

Demodulation Frame Unit

Antenna Diversity Carrier Unit,Frame Unit

Radio Link Recovery Frame Unit

Radio Resource Indication Frame Unit

Paging Frame Unit

DTX Frame Unit

DRX Frame Unit

Quality Measurement Frame Unit

Power Control Frame Unit

Clock Distribution Frame Unit

Protocol Management Frame Unit

Radio Channel Management Frame Unit

Transcoder Time Alignment Frame Unit

Table 11: Functional Block to Functional Unit Mapping - Telecommunication Baseband

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7.3.3 Telecommunication RF


RF Carrier Generation Carrier Unit

Frequency Hopping - Realized by Station Unit

Frequency Hopping - Performed by Station Unit

Frequency Hopping - Controlled by Station Unit

GMSK Modulation Carrier Unit

Up-conversion Carrier Unit

Power Amplification and Power Control Carrier Unit

Power Coupling and Detection Carrier Unit

Channel Selection and Conversion Carrier Unit

Signal Amplification Carrier Unit

A-D Conversion Carrier Unit

Digital Pre-processing Carrier Unit

Control the Status of the RF Hardware Carrier Unit

Clock Selection and Supervision Station Unit

Program the Local Oscillators/Frequency Synthesizers Carrier Unit

Handle Control and Alarm Processing Carrier Unit

Select the High or Low Gain Path on the Uplink Carrier Unit

Downlink Isolating Coupling Unit

Downlink Combining Coupling Unit

Downlink Duplexing Coupling Unit

Downlink Power Coupling and Detection Coupling Unit

Uplink Antenna Pre-amplification Coupling Unit

Uplink Low Noise Pre-amplification (RFE function) Coupling Unit

Uplink Signal Splitting (Duplexing) Coupling Unit

Table 12: Functional Block to Functional Unit Mapping - Telecommunication RF

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7.3.4 O&M


Configuration Management Station Unit,Frame Unit

Fault Management Station Unit,Frame Unit

Dedicated Alarm Handling Station Unit

External Alarm Handling Station Unit

Central Command Control Station Unit,Frame Unit

Configuration/Initialization Station Unit,Frame Unit

Software Replacement Station Unit,Frame Unit

Configuration Parameter File Management Station Unit

Testing Station Unit

Alarm Detection, Filtering and Correlation Station Unit

Alarm Forwarding Station Unit

Alarm Translation Station Unit

Command Translation Station Unit

Table 13: Functional Block to Functional Unit Mapping - O&M

7.3.5 Support


Clock Generation and Distribution Station Unit

External Alarm Collection Station Unit

Internal Self-tests Station Unit,Frame Unit,Carrier Unit

Table 14: Functional Block to Functional Unit Mapping - Support

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8 G1/G2 BTS Functional Units


This chapter describes the breakdown of the G1 BTS Mark2 and G2 BTSinto their functional units:

Frame Unit

Station Unit

Carrier Unit

Coupling Unit.

The following information is provided for each functional unit:

Short functional description of each unit’s functions

List of external interfaces

List of hardware modules on which the functions are realized

Mapping of hardware modules against functions

Possible configurations.

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8.1 G1/G2 BTS Functional Units BreakdownThe G1/G2 BTS contains the following functional units:

Frame Unit

Station Unit

Carrier Unit

Coupling Unit.

Each functional unit can use a number of different submodule types, dependingupon hardware variant and BTS configuration.

The functional units and submodules are described in the subsequent sections.

8.2 G1/G2 BTS Frame UnitThe Frame Unit performs baseband processing on traffic and signallingbetween the BTS Air Interface and the Abis Interface. It also provides a rangeof O&M functions.

The Frame Unit:

Adapts downlink traffic and signalling to a format suitable for transmission

over the Air Interface.

Under control of the BSC, maps the logical channels onto physical channelsfor the downlink.

Processes uplink samples delivered by the Carrier Unit, to recover the

baseband data.

Monitors its own status, and the status of its external interfaces.

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8.2.1 G1/G2 BTS Frame Unit Functional Entities

The principal functional entities in a Frame Unit are shown in the following figure.

OMU(locatedin StationUnit)

DCL1

Traffic

Clock Links

StationUnit

StationUnit

FrequencyHoppingInterface

FHILinks

EncoderTraffic

Control

Clocks

Traffic Traffic Traffic

LAPD

Frame UnitController

Frame ClockUnit

BSI

AbisInterface

DemodulatorChannelDecoder

Base StationInterfaceAdaptater

Figure 12: G1/G2 BTS, Frame Unit Functional Entities and Interfaces

The figure shows the non-diversity case. When Antenna Diversity is used, theuplink path for both traffic and signalling is duplicated. This duplication startsat the antenna and continues up to the output of the Channel Decoder. Thefunctions of the duplicated path are identical to those of the non-diversity casedescribed in the following sections.

The principal functional entities in a Frame Unit are:

Frame Unit Controller

Encoder

Channel Decoder

Demodulator

FHI

FCLU

BSIA.

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The following table shows how the Frame Unit functions map on to the FrameUnit functional entities. In some cases, a single functions can be split betweenmore than one entity.

Functions

FrameUnitController Encoder

ChannelDecoder Demodulator


FrameClockUnit

BaseStationInterfaceAdapter

Rate Adaptation - X X - - - -

Channel Encoding/Decoding

- X X - - - -

Interleaving/De-interleaving

- X X - - - -

Encryption/ Decryption X X - X - - -

Demodulation - - - X - - -

Antenna Diversity X - X X - - -

DiscontinuousTransmission

X X X - - - -

Protocol Handling X X X X - - -

Radio ChannelManagement

X X X X - - -

Radio ResourceIndication

X - X - - - -

Paging X - - - - - -

Transcoder TimeAlignment

X X X X - - -

Quality Measurements X - X - - - -

Power Control X X X - - - -

Frame UnitDownloading

X X X X - - -

Frame UnitConfiguration

X X X X X X X

Frame Unit Control X (X) (X) (X) (X) (X) (X)

Fault Management X X X X X X X

RF Self-test X X X X - - -

PerformanceMeasurements

X - X X - - -

Trace and Debug X - - - - - -

Off-line Tests X X X X X X X

- (X) = Self-control- - - - -

Table 15: G1/G2 BTS, Distribution of Frame Unit Functions between Frame Unit Functional Entities

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8.2.1.1 Frame Unit ControllerThe Frame Unit Controller handles the protocol management for Layers 2and 3, which implement the following telecommunications and O&M functions:

Radio Channel Management

Power Control

Quality Measurements

Paging

Maintenance

Time Synchronization.

The Frame Unit Controller manages the following protocols:

Layer 2 - LAPDmThe LAPDm protocol operates over the BTS -Mobile Station link. It isresponsible for ensuring error free, point-to-point communications usingLAPDm frames (GSM rec. 04.06).

At Layer 2, LAPDm provides services for the following radio channels:

SDCCH

FACCH

SACCH.

On these channels LAPDm performs connection establishment, data transferand connection release. Services to other radio channels are handled atLayer 3 to avoid excessive transfers between Layers 2 and 3. LAPDm thuscarries information between Layer 3 entities, via the Air Interface.

Layer 2 - LAPDThe LAPD operates over the Abis link between the BTS and BSC (GSMrec. 04.06). LAPD is responsible for ensuring error-free, point-to-pointcommunication between the Frame Unit and the BSC. It also carriesinformation between Layer 3 entities via the subscriber network interface.

8.2.1.2 EncoderThe Encoder processes baseband data for the downlink. It provides thefollowing functions:

Rate Adaptation

Transcoder Synchronization

Baseband functions, depending on logical channel type:

Channel Encoding

Interleaving

Encryption

Burst Building and TDMA Multiframe Building.

Power Control

DTX functions.

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8.2.1.3 Channel DecoderThe Channel Decoder processes uplink information carried by one time slotof the TDMA frame. The Decoder performs complex processing on thedemodulated and decrypted data, which involves the following stages:

Antenna diversity combining

Quality estimation for link control

De-interleaving

Convolutional decoding

Block decoding

FACCH detection

Signalling packet extraction

Silence Indication frame detection

Rate Adaptation

Inband control of Transcoder

Processing of test data

Filtering of TOA

Filtering of received signal level

Carrier Unit monitoring

Access burst decoding

Filtering of RF self-test parameters.

The Channel Decoder produces two parameters for signal quality. These relateto measurements made during a SACCH multi-frame, over a full set of TDMAframes, and a subset of TDMA frames, respectively. The Channel Decodersends these parameters to the Frame Unit Controller.

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8.2.1.4 DemodulatorThe Demodulator processes the complex samples of the digital basebandcorresponding to one time slot within a TDMA frame. It performs the followingfunctions:

Buffering of the digitized samples

Decryption

GMSK demodulation

Estimation of the channel impulse response

TOA estimation

Estimation and correction of the carrier frequency offset

Equalization based on the estimated channel impulse response

Soft decision output

SNR measurement

Frame Unit and Carrier Unit RF self-tests.

8.2.1.5 Frequency Hopping InterfaceThe FHI connects the Frame Unit to the Frequency Hopping function in theStation Unit, via high-speed serial links. In this way the Frame Unit is interfacedto the Carrier Unit via the Station Unit.

8.2.1.6 Frame Clock UnitThe FCLU provides timing for all functions in the Frame Unit. It is locked to theStation Unit, where the master time reference in the BTS is generated. TheFCLU generates the time slot clock, and distributes these signals.

8.2.1.7 Base Station Interface AdaptorThe BSIA controls:

Selection and supervision of up to two incoming BSIs.

Parallel to serial conversion between the Channel Decoder and the BSIfor the TCH.

Electrical adaptation to the Channel Encoder for TCH, and to/from the

Frame Unit Controller for signalling channels.

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8.2.2 G1/G2 BTS Frame Unit External Interfaces

As shown in Figure 12 , the Frame Unit exchanges data with external entitiesthrough four different types of interface. These are described in the followingtable.


BSI Links 0 & 1 These provide links with the BSC (LAPD management)and the Transcoder (TRAU) frame management).Only one link is used at a time; BSI Link 1 is usedonly if BSI Link 0 is down.These links exchangetelecommunications parameters with the BSC.

Clock Links 0 & 1 These links provide clocks to the BTS units. Duringnormal operation, both clock links are used to carry thesame information, providing a level of redundancy.Thelinks provide the Frame Unit with two clock signals andthe Frame Number.

FHI Links 0 & 1 These links enable the Frame Unit to communicatewith the Station Unit’s Frequency Hopping function:

FHI link 0 allows the Frame Unit to communicatewith Frequency Hopping function 1

FHI link 1 allows the Frame Unit to communicatewith Frequency Hopping function 2.

During normal operation, both FHI links are used. Inthe case of no antenna diversity they carry the sameinformation, thus providing an element of redundancy.

DCL1 The DCL1 allows communication with the Station Unit.It is managed using the Token Passing Bus AccessMethod. This interface receives O&M commands,configuration data and downloaded software, andsends alarms and commands to the Station Unit.Note that communication between Frame Units is notpossible via this interface.

Table 16: G1/G2 BTS, Frame Unit, External Interfaces

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8.2.3 G1/G2 BTS Frame Unit Submodules

Depending upon the configuration, the Frame Unit contains a specific set ofsubmodules that is dependent on the following BTS hardware configurations:

G1 BTS Mark2

G2 BTS.

8.2.3.1 G1 BTS Mark2The G1 BTS Mark2 BTS Frame Unit contains:

FUCO

CECC

DMAD

DMOD

CDEC

FUIF

DRFU

DRFE.

8.2.3.2 G2 BTSThe G2 BTS Frame Unit contains either a single-board or or a three-boardFrame Unit:

The single-board Frame Unit:DRFU

The three-board Frame Unit (only if the GPRS feature is not implemented on

the network) with:

FUCO

FICE

DADE.

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8.2.4 G1/G2 BTS Frame Unit Submodule Functions

The following table lists the functional entities against the Frame Unitsubmodules that physically contain those entities.

Functional Entity G1/Mark2 G2

Frame Unit Controller FUCO 1)

DRFU

FUCO 1)

DRFU

Encoder CECC

DRFU

FICE

DRFU

Channel Decoder CDEC

DRFU

DADE

DRFU

Demodulator DMOD

DMAD

DRFU

DADE

DRFU

Frequency Hopping Interface FUIF

DRFU

FICE

DRFU

Frame Clock Unit FUIF

DRFU

FICE

DRFU

Base Station Interface Adapter FUIF

DRFU

DRFE

FICE

DRFU

Table 17: G1/G2 BTS, Frame Unit Functional Entities and Submodules

1) (Only if the GPRS feature is not implemented on the network.)

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8.2.5 G1/G2 BTS Frame Unit Configurations

8.2.5.1 G1 BTS Frame UnitThere are two G1 BTS Frame Unit configurations:

Mark2 multi-board (Only if the GPRS feature is not implemented on thenetwork.)

Mark2 single-board.

Both following figures show the possible configurations.

The following figure shows the G1 BTS Mark2 multi-board Frame Unit, withoutantenna diversity.

CECC

DMOD

CDEC

BSC

FQHU

Control

Data

Clocks

Data

Clocks

FUCO

FUIF

OMUA DCL1

MCLU or MCLR

Clocks

BSIs

Data

Clocks

Clocks

Data

FHIs

Figure 13: G1 BTS, Mark2 Multi-board Frame Unit (Without Antenna Diversity)

Note: If antenna diversity is used, the DMAD replaces the DMOD.

The single-board DRFU and the DRFE can replace the Mark2 multi -boardFrame Unit for half-rate and enhanced full-rate channels.

The following figure shows the G1 BTS Mark2 single-board Frame Unit DRFUwith the DRFE.

BSC

FHIsFQHU

DRFU

DCL1

MCLU or MCLR

Clocks

BSIs

OMUA DRFEDCL1

Figure 14: G1 BTS Mark2 Single-board Frame Unit

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8.2.5.2 G2 BTS Frame UnitThere are two G2 BTS Frame Unit configurations:

Three-board (Only if the GPRS feature is not implemented on the network.)

Single-board.

Both following figures show the possible configurations.

The following figure shows the G2 BTS three-board Frame Unit, with or withoutdiversity.

DADE

FUCO

BSC

FHIsSTSE or STSR or STSP

Control

Data

FICE

DCL1

STSE or STSR or STSPClocks

BSIs

Clocks

Clock

Data

SCFE

Figure 15: G2 BTS Three-board Frame Unit

The G2 BTS single-board Frame Unit DRFU can replace the G2 BTSthree-board Frame Unit. For reasons of physical size, high power BTSs mustuse the single-board Frame Unit. For half-rate and enhanced full-rate channels,the DRFU must be used.

The following figure shows the G2 BTS single-board Frame Unit.

BSC

FHIsSTSE or STSR or STSP

DRFU

DCL1

STSE or STSR or STSPClocks

BSIs

SCFE

Figure 16: G2 BTS Single-board Frame Unit

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8.3 G1/G2 BTS Station UnitThe Station Unit interfaces the Frame Unit to the Carrier Unit, and provides themain O&M functions for the BTS. These O&M functions are:

Download the BTS software from the BSC

Continuously monitor the operation of the BTS

Generate the main clocks for the BTS

Provide switching for the frequency hopping function.

8.3.1 G1/G2 BTS Station Unit Functions

The Station Unit contains the following functions:

Master Clock Generation

Master Clock Selection and Supervision

Timing Signal Generation

Clock Distribution

Master Clock Control

Message Control

Frequency Hopping

O&M


External Alarm Connection

RF Self-test.

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The following figure shows the logical functions of the Station Unit togetherwith its internal interfaces.

MasterClockControl

ClockDistribution

MessageControl

TimingSignalGeneration

MasterClockSelection &Supervision

MasterClockGeneration

DCL2

Clocks (duplicated links)

FHI links

FrequencyHopping

DLC2

FrequencyNumber

DLC2

DLC2

RF Self−test

DedicatedAlarm andCotrolHandling

ExternalAlarmConnection

DLC2

MMI

BTSTerminal

BSIBIEO&M

CarrierUnits

CarrierUnits

Timing and switching(duplicated)

CouplingUnit

RF self−test

Control

Non−intelligentBTSComponents

ExternalAlarmSources

Frame Units

Frame Units(& Slave BTS)

Other IntelligentBTS Submodules

Frame Units

BSC (via AbisInterface)

FHI links

Clocks (duplicated links)

DCL2

DCL1

DedicatedAlarms/Control

Figure 17: G1/G2 BTS, Station Unit Logical Functions and Interfaces

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8.3.2 G1/G2 BTS Station Unit External Interfaces

As shown in the previous figure, there are seven types of Station Unit interfacedescribed in the following table.


BSI The BSI connects the OMU to the BSC via the AbisInterface using the BIE.

FHI The FHI link carries traffic and control data from the FrameUnits to the Station Unit, and from the Station Unit to theCarrier Units (and vice-versa).

Clock Links These duplicated links distribute the clocks to the CarrierUnits, Frame Units, RF self-test function and collocatedslave BTSs.

DCL1 DCL1 is a high-speed link between the OMU and FrameUnits. As well as carrying alarm and status information,the DCL1 is used for software downloading to the FrameUnits.

DCL2 DCL2 is a slower link connecting to all other intelligentequipment (for example, Carrier Units) that only requireparameter and alarm transfer.

DedicatedAlarm andControl

Non-intelligent BTS submodules are connected viadedicated, simple alarm and control lines.

MMI The MMI allows the connection of an operator’s terminal,through which the BTS can be locally controlled.

Table 18: G1/G2 BTS, Station Unit, External Interfaces

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8.3.3 G1/G2 BTS Station Unit Submodules

Depending upon the configuration, the Station Unit contains a specific set ofsubmodules that is dependent on the following BTS hardware configurations:

G1 BTS Mark2

G2 BTS (GSM 900, GSM 900 Extended Cell, and GSM 1800).

8.3.3.1 G1 BTSThe G1 BTS Station Unit contains:

MFGE

MFPG (PCM)

MCLU (for master BTSs)

MCLR (for slave BTSs)

FQHU

OMUA

EACB

EAIB

RTEM.

8.3.3.2 G2 BTSThe G2 BTS Station Unit contains:

SCFE

SACE

SRSE (for master BTSs)

STSP (for master BTSs)

STSR (for slave BTSs)

ESTS (for master BTSs)

ESTR (for slave BTSs)

RTEG or RTED.

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8.3.4 G1/G2 BTS Station Unit Submodule Functions

The following table indicates the functions performed by the Station Unitsubmodules.

Function G1 G2/GSM 900G2/GSM 900Extended Cell G2/GSM 1800

Master Clock Generation MFGE

MFGP

STSE

STSP

ESTS STSE

STSP

Master Clock Selection andSupervision

MCLU STSE

STSP

ESTS STSE

STSP

Timing Signal Generation MCLU

MCLR

STSE

STSP

STSR

ESTS

ESTR

STSE

STSP

STSR

Clock Distribution MCLU

MCLR

STSE

STSP

STSR

ESTS

ESTR

STSE

STSP

STSR

Master Clock Control MCLU

MCLR

STSE

STSP

STSR

ESTS

ESTR

STSE

STSP

STSR

Message Control MCLU

MCLR

STSE

STSP

STSR

ESTS

ESTR

STSE

STSP

STSR

Frequency Hopping FQHU STSE

STSP

STSR

ESTS

ESTR

STSE

STSP

STSR

Operations and Maintenance OMUA SCFE SCFE SCFE

Dedicated Alarm and ControlHandling

EACB SCFE/SACE SCFE/SACE SCFE/SACE

External Alarm Connection EAIB SCFE/SACE SCFE/SACE SCFE/SACE

RF Self-test RTEM RTEG RTEG RTED

Table 19: G1/G2 BTS, Station Unit Functions and Submodules

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8.3.5 G1/G2 BTS Station Unit Configurations

8.3.5.1 G1 BTS Station UnitThe following figure shows the G1 BTS Station Unit used in a master BTS.

RTEM

OMUA

EAIB

EACB 1

EACB 2

EACB n

BSC

MMI DCL 1

BSIs

DCL 2

MCLRs in Slave BTS(for synchronization)

Carrier Units 1...16 Frame Units 1...16

Frame Units 1...16

Carrier Units 1...16

Combiner

Receiver Front−End

External Alarm Inputs

Control Outputs

"Non−intelligent" Units


DCL2

DCL2

DCL2

DCL2 Carrier Units (5..16)

Carrier Units (1...4)

FQHU

MCLU

Clocks Clocks

FHI

FHI

"Non−Intelligent" Units within the Station Cabinet

MFGE or MFGP

BTSTerminal

Frame Units

Figure 18: G1 BTS Station Unit (Master)

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The configuration of the G1 BTS Station Unit equipment depends on the type ofmaster clock generation. That is, whether the BTS is a:

Free-running master

PCM synchronized master

Slave.

In slave BTSs (which repeat their timing signals from a local master), theduplicated MFGEs/MFGPs are not used. The MCLRs replace the duplicatedMCLUs.

8.3.5.2 G2 BTS Station UnitThe configuration of G2 BTS Station Unit equipment depends on the type ofmaster clock generation. That is whether the BTS is a:

Free-running master

PCM synchronized master

Slave.

Both following figures show the possible G2 BTS Station Unit configurations.

The following figure shows a G2 BTS single-carrier (master/slave) Station Unit.

SCFE

Carrier Unit

Frame Unit

Frame Units


DCL1

DCL2

BSIs

MMI

External Alarms

BSC

BTS Terminal

Clocks 1)

1) to slave BTS in case of a master Station Unit

from Master BTS in case of a slave Station Unit

Clocks/Data

Clocks/Data

Alarm

Carrier Units, and other "Intelligent" Units

Alarms/Control

Master/ Slave BTS

STSEor

STSPor

ESTS

Figure 19: G2 BTS Single-carrier Station Unit

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The following figure shows a G2 BTS multi-carrier (master/slave) StationUnit, with redundancy.

SCFE

SACE

Frame UnitsClock/Data

Carrier UnitsClock/Data

RTEG/RTEDClocks

DCL2

Frame UnitsDCL1


"Non−intelligent" UnitExternal Alarms

BSIs

MMI

External Alarm

BSC

BTS Terminal

Alarms

Alarms

Clocks 1)

1) to slave BTS in case of a master Station Unit

from Master BTS in case of a slave Station Unit

STSEor

STSP

Alarms/Control

Carrier Units, RTEG/RTED and other "Intelligent" Units

Alarms/ Control

Master/Slave BTS

Figure 20: G2 BTS Multi-carrier Station Unit with Redundant Timing andSwitching Functions

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8.4 Carrier UnitThe Carrier Unit interfaces the digital baseband signals present in the FrameUnit, to the RF signals used on the Air Interface.

To achieve this, the Carrier Unit:

Generates and modulates the RF carrier for the downlink

Dynamically regulates power on the downlink for each time slot

Receives RF signals transmitted by the Mobile Station on the uplink

Delivers a preprocessed uplink signal to the Frame Unit, ready for

demodulation.

The Carrier Unit is described in the following sections:

Functions

External Interfaces

Submodules

Submodule Functions.

8.4.1 G1/G2 BTS Carrier Unit Functions

The Carrier Unit performs the following functions:

Control

Downlink:

GMSK Modulation

Up-conversion

Power Amplification

Power Coupling and Detection.

Uplink:

Down-conversion


A-D Conversion

Digital Pre-processing.

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A block diagram of a non-diversity Carrier Unit is shown in the following figure.

PowerCouplingand Detection

RF outPowerAmplification

Up−conversion

IQ

Clocks

DCL2

FHI1

*FHI2

StationUnit

Oscillator Osillator

Down−conversion

SignalAmplification

I

Q A−DConversion

DigitalPre−processing

Control

Uplink Direction

Downlink Direction

GMSKModulation


Oscillator

* FHI Links

RF in

Figure 21: G1/G2 BTS, Non-diversity Carrier Unit Functions

When Antenna Diversity is used, the uplink path for both traffic and signallingis duplicated. This duplication starts at the antenna and continues up tothe output of the Channel Decoder in the Frame Unit. The functions of theduplicated path are identical to those of the non-diversity case described in thefollowing sections.

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8.4.2 G1/G2 BTS Carrier Unit External Interfaces

The interfaces that link the Carrier Unit with other BTS units are shown in theprevious figure and can be split into two types:

Interfaces to the Coupling Unit

Interfaces to the Station Unit.

8.4.2.1 Interfaces to the Coupling UnitThere are two interfaces from the Carrier Unit to the Coupling Unit in anon-diversity configuration. A diversity configuration includes an additionaluplink RF input.

The interfaces are:

RF outputThe downlink RF signal is output to the Coupling Unit for transmission viathe antenna.

RF input.The uplink RF signal from the receive antenna is input to the Carrier Unitfrom the Coupling Unit. In the case of antenna diversity there are twoRF inputs.

8.4.2.2 Interfaces to the Station UnitThere are three interfaces from the Carrier Unit to the Station Unit:

FHIThe FHI connects the Carrier Unit to a link switch in the Station Unit. Thisroutes each time slot to the appropriate Frame Unit. The data sent overthis link comprises the receive data, transmit data and test data. Two FHIlinks operate in parallel, which meets the requirement either for antennadiversity or redundancy.

Clock interface

The Clock interface includes the following clock signals from the Station Unit:

REFCLK (13 MHz)

OBCLK (2.16 MHz)

FCLK (216 Hz)

Two links provide redundancy.

DCL2.The DCL2 Interface is the bidirectional link between the Carrier Unit andOMU in the Station Unit. Via this interface the Station Unit handles theCarrier Unit configuration and fault management.

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8.4.3 G1/G2 BTS Carrier Unit Submodules

Depending upon the configuration, the Carrier Unit contains a specific set ofsubmodules that is dependent on the following BTS hardware configurations:

G1 BTS Mark2

G2 BTS GSM 900

G2 BTS GSM 1800.

8.4.3.1 G1 BTS Mark2The G1 BTS Mark2 Carrier Unit contains:

TXUA

TXAL

TXAH

RXUA

RXAS.

8.4.3.2 G2 BTS GSM 900The G2 BTS GSM 900 BTS Carrier Unit contains:

TXGM

TXGH

TEGM

RXGD.

8.4.3.3 G2 BTS GSM 1800The G2 BTS GSM 1800 BTS Carrier Unit contains:

TXDH

RXDD.

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8.4.4 G1/G2 BTS Carrier Unit Submodule Functions

The next three tables indicate the functions which the Carrier Unit submodulesperform:

Control function submodules

Downlink function submodules

Uplink function submodules.

8.4.4.1 Control Function SubmodulesThe following table shows the Carrier Unit control function submodules.

Function G1G2/GS M900

G2/GSM 1800

Control Functions TXUA

TXAL

TXAH

TXGM

TXGH

TEGM

TXDH

Table 20: G1/G2 BTS, Carrier Unit Control Function Submodules

8.4.4.2 Downlink Function SubmodulesThe following table shows the Carrier Unit downlink function submodules.

Function G1G2/GSM 900

G2/GSM 1800

GMSK Modulation TXUA

TXAL

TXAH

TXGM

TXGH

TEGM

TXDH

Up-conversion TXUA

TXAL

TXAH

TXGM

TXGH

TEGM

TXDH

Power Amplification TXUA

TXAL

TXAH

TXGM

TXGH

TEGM

TXDH

Power Coupling and Detection TXUA

TXAL

TXAH

TXGM

TXGH

TEGM

TXDH

Table 21: G1/G2 BTS, Carrier Unit Downlink Function Submodules

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8.4.4.3 Uplink Function SubmodulesThe following table shows the Carrier Unit uplink function submodules.

Function G1G2/GSM 900

G2/GSM 1800

Down-conversion RXUA

RXAS

RXGD RXDD

Signal Amplification RXUA

RXAS

RXGD RXDD

A-D Conversion RXUA

RXAS

RXGD RXDD

Digital Pre-processing RXUA

RXAS

RXGD RXDD

Table 22: G1/G2 BTS, Carrier Unit Uplink Function Submodules

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8.4.5 G1/G2 BTS Carrier Unit Configurations

8.4.5.1 G1 BTS Carrier UnitThe following figure shows the G1 BTS Carrier Unit, with antenna diversity.

Coupling Unit

RF in(Diversity)

RF in

RF out

Receiver(Diversity)

Receiver

Control Data

Transmitter

FHIs DCL2 Clocks

SU

Coupling Unit

Figure 22: G1 BTS Carrier Unit (Antenna Diversity)

Note: Where antenna diversity is not used, only one receiver is employed.

The various G1 BTS receiver/transmitter types can only be used in thecombinations TXUA/RXUA, TXAL/RXAS, TXAH/RXAS. Within any one BTS,the transmitter/receiver types cannot be mixed. Antenna diversity operationrequires the use of two receivers per Carrier Unit.

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8.4.5.2 G2 BTS Carrier UnitThe following figure shows the G2 BTS Carrier Unit.

CouplingUnit

RF in(Diversity)

RF in

RF out

Receiver

Control Data

Transmitter

FHIs DCL2 Clocks

SU

CouplingUnit

Figure 23: G2 BTS Carrier Unit

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8.5 G1/G2 BTS Coupling UnitThe Coupling Unit interfaces the Carrier Unit with the transmit and receiveantennas. The Coupling Unit:

Ensures the efficient transfer of RF power to the transmit antenna

Enables all BTS transmitters to share a single antenna

Protects the Carrier Unit from damage by reflected RF power

Allows BCCH recovery in the event of Carrier Unit failure

Isolates the transmit frequencies from the receiver

Enables the receiver to share the transmit antenna

Provides pre-amplification of the received uplink signal.

The Coupling Unit functions are:

Downlink functions (BTS to Mobile Station)

Uplink functions (Mobile Station to BTS).

The Coupling Unit is described in the following sections:

Functions

External Interfaces

Submodules

Submodule Functions.

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8.5.1 G1/G2 BTS Coupling Unit Functions

The Coupling Unit functions are divided into two types:

Downlink

Uplink.

8.5.1.1 Downlink FunctionsThe Coupling Unit downlink functions performed by combiners are:

Isolation and Reflected Power Load

Summing

Transmit Filter

Antenna Directional Coupling

Antenna VSWR Alarm Unit

RTC Control

BCCH-Carrier Recovery.

The following figure shows a simplified block diagram of the downlink couplingfunctions and interfaces.

TransmitFilter

AntennaDirectionalCoupling

AntennaVSWRAlarm Unit

Summing

Isolationwith Load

Isolationwith Load

Isolationwith Load

Transmitter 1

Transmitter 2

Transmitter n

TransmitAntenna

RF Self−test

Station Unit

Figure 24: G1/G2 BTS, Downlink Coupling Functional Block Diagram

Note: Single-carrier combiners contain no summing function, but provide faultprotection functions.

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8.5.1.2 Uplink FunctionsThe Coupling Unit uplink functions performed by RFEs are:

Bandpass Filter

Directional Coupling to Test Interface


Power Splitting

Control

Additional Antenna Pre-Amplifier.

The following figure shows the uplink coupling functions and interfaces.

Antenna

BandpassFilter

DirectionalCouplingto TestInterface

SignalAmplification

PowerSplitting

Control

RF Self−test

Receiver 1

Receiver n

Station Unit

Figure 25: G1/G2 BTS, Uplink Coupling Functional Block Diagram

The figure shows the non-diversity case. When Antenna Diversity is used, theuplink path is duplicated. All of the coupling functions are duplicated. Thesefunctions are identical to those of the non-diversity case described in thefollowing sections.

The Antenna Pre-amplifier’s RFE replaces the normal RFE in BTSs with long,lossy (2 dB to 8 dB) antenna cables. It consists of two separate sub-modules:

Tower Mounted AmplifierThe Tower Mounted Amplifier is located at the base of the antenna andprovides filtration and initial amplification of the received signal.

Antenna Pre-amplifier RFEThe Antenna Pre-amplifier RFE replaces the usual RFE. It further amplifiesthe RF signal from the Tower Mounted Amplifier before dividing it betweenthe receivers. Fault -tolerant Signal Amplification pairs are employedwhether antenna diversity is used or not.

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The following figure shows a simplified diagram of the Antenna Pre-amplifier.

Receive Antenna

Filter

Long RF Cable

Antenna Pre−amplifier’s RFE

Tower Mounted Amplifier

Receiver 1

Control

Receiver n

Pilot Tone Detection

Test Loop Coupling


Power Splitter 1 8

Pilot Tone Detection

Pilot ToneInjection

SignalAmplification

Figure 26: G1/G2 BTS, Antenna Pre-amplifier Simplified Block Diagram

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8.5.2 G1/G2 BTS Coupling Unit External Interfaces

The Coupling Unit uses two types of interface:

External interfaces used by the Coupling Unit

External interfaces used by the RFE.

8.5.2.1 External Interfaces used by the Coupling UnitThere are four interfaces used by the Coupling Unit as shown in Figure 24 :

Transmitter RF inputs, where one RF input is provided for each transmitteroutput

Antenna RF output, which connects the Coupling Unit output to the transmitantenna

RF Self-test output, which provides a low power RF output for use in RF

Self-tests

Station Unit Interface, which connects control and alarm signals to andfrom the Station Unit.

8.5.2.2 External Interfaces used by the RFEThe RFE has a set of four interfaces as shown in Figure 25 :

Antenna RF input, where a single input allows connection of a receiveantenna

RF Self-test input, which provides the RF input from the RF Self-test function

RF outputs, where a separate RF output is provided for each receiverin the Carrier Unit

Station Unit Interface, which connects control and alarm signals to/from the

Station Unit.

As shown in Figure 26 , the Antenna Pre-amplifier has an additionalintermediate interface. This carries the pre-amplified received RF signal fromthe Tower Mounted Amplifier to the RFE; and a DC power feed from theRFE to the Tower Mounted Amplifier.

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8.5.3 G1/G2 BTS Coupling Unit Submodules

Depending upon the configuration, the Coupling Unit contains a specific set ofsubmodules that is dependent on the following BTS hardware configurations:

G1 BTS Mark2

G2 BTS GSM 900

G2 BTS GSM 1800.

8.5.3.1 G1 BTS Mark2The G1 BTS Mark2 contains:

CBC2

CBC4

CEC2

CEC4

FBC2

FEC2

FCAV

RXFE

RXDE

RTDE

RTSE

CRFE

CRDE

MCEX

RTMA.

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8.5.3.2 G2 BTS GSM 900The G2 BTS GSM 900 BTS Coupling Unit contains:

WB1G

WB2G

DUPG

FRBG

FREG

CRBG

CREG

FEG2

FEG8

RMCG

TMAG.

8.5.3.3 G2 BTS GSM 1800The G2 BTS GSM 1800 BTS contains:

WB2D

DUPD

DUD2

RC4D

RC8D

FED2

FED8

RMCD

TMAD.

8.5.4 G1/G2 BTS Coupling Unit Submodule Functions

The Coupling Unit submodules perform two types of functions:

Downlink

Uplink.

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8.5.4.1 G1/G2 BTS, Coupling Unit Downlink Function SubmodulesThe following table indicates the Coupling Unit downlink function submodules.

Function G1/Mark2 G2/GSM 900 G2/GSM 1800

Isolation with Power Load FBC2/FCAV/FEC2

CBC2

CBC4/CEC2

CBC4/CEC4

WB1G

WB2G

DUPG

CRBG/CREG

FRBG/FREG

WB2D

DUPD

DUD2

RC4D

RC8D

Summing FBC2/FCAV/FEC2

CBC2

CBC4/CEC2

CBC4/CEC4

WB1G

WB2G

DUPG

CRBG/CREG

FRBG/FREG

WB2D

DUPD

RC4D

RC8D

Transmit Filter FBC2

CBC2

CBC4

WB1G

WB2G

DUPG

CRBG

FRBG

WB2D

DUPD

DUD2

RC4D

RC8D

Antenna Directional Coupling FBC2

CBC2

CBC4

WB1G

WB2G

DUPG

CRBG

FRBG

WB2D

DUPD

DUD2

RC4D

RC8D

Antenna VSWR Alarm Unit FBC2

CBC2

CBC4

WB1G

WB2G

DUPG

CRBG

FRBG

WB2D

DUPD

DUD2

RC4D

RC8D

RTC Control FBC2

CBC2

CBC4

CRBG

FRBG

RC4D

RC8D

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BCCH-carrier Recovery FBC2

CBC2

CBC4

WB1G

WB2G

DUPG

CRBG

FRBG

WB2D

DUPD

DUD2

RC4D

RC8D

Integrated Duplexing – DUPG DUPD

DUD2

Table 23: G1/G2 BTS, Coupling Unit Downlink Function Submodules

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8.5.4.2 G1/G2 BTS, Coupling Unit Uplink Function SubmodulesThe following table indicates the Coupling Unit uplink function submodules.


Bandpass Filter RXFE

RXDE

RTSE

RTDE

CRFE

CRDE

FEG2

FEG8

TMAG

FED2

FED8

TMAD

Directional Coupling to Test Interface RXFE

RXDE

RTSE

RTDE

CRFE

CRDE

FEG2

FEG8

RMCG

FED2

FED8

RMCD

Signal Amplification RXFE

RXDE

RTSE

RTDE

CRFE

CRDE

RTMA

FEG2

FEG8

RMCG

TMAG

FED2

FED8

RMCD

TMAD

Power Splitting RXFE/MCEX

RXDE/MCEX

RTSE/MCEX

RTDE/MCEX

CRFE

CRDE

FEG2

FEG8

RMCG

FED2

FED8

RMCD

Control RXFE

RXDE

RTSE

RTDE

CRFE

CRDE

FEG2

FEG8

RMCG

FED2

FED8

RMCD

Additional Antenna Pre-amplifier RTMA/RTSE

RTMA/RTDE

TMAG/RMCG TMAD/RMCD

Table 24: G1/G2 BTS, Coupling Unit Uplink Function Submodules

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8.5.5 G1/G2 BTS Coupling Unit Configurations

The configuration of Coupling Unit equipment depends on the number oftransmitters and receivers that are served. The configuration also dependson the support of antenna diversity.

8.5.5.1 G1 BTS Coupling UnitThe following table shows the possible G1 BTS Coupling Unit configurations,for various numbers of carriers.

No. ofCarriers Coupling Function Mark2

2 Downlink FBC2 or CBC2

Uplink (non-diversity) CRFE or RXFE/MCEX orRTMA/RTSE/MCEX

Uplink (diversity) CRDE or RXDE/2 x MCEX or 2 xRTMA/RTDE/2 x MCEX

4 Downlink FBC2/FCAV or CBC4

Uplink (non-diversity) CRFE or RXFE/MCEX orRTMA/RTSE/MCEX


6 Downlink FBC2/FCAV/FEC2 or

Uplink (non-diversity) CRFE or RXFE/2 x MCEX orRTMA/RTSE/2 x MCEX


8 Downlink FBC2/FCAV/2 x FEC2 orCBC4/CEC4

Uplink (non-diversity) CRFE or RXFE/2 x MCEX orRTMA/RTSE/2 x MCEX


Table 25: G1 BTS, Coupling Unit Combinations

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8.5.5.2 G2 BTS Coupling UnitThe following table shows the possible G2 BTS Coupling Unit configurations forvarious numbers of carriers.

No. ofCarriers Coupling Function GSM 900 GSM 1800

1 Downlink WB1G

WB2G

DUPG

WB2D

DUPD

DUD2

Uplink 2 x FEG2 2 x FED2

- 2 x TMAG/RMCG 2 x TMAD/RMCD

2 Downlink WB2G

DUPG

WB2D

DUPD

DUD2



4 Downlink FRBG

CRBG

2 x DUPG

RC4D

RC8D

2 x DUPD

2 x DUD2



8 Downlink FRBG/FREG

CRBG/CREG

RC8D



Table 26: G2 BTS Coupling Unit Combinations

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8.5.5.3 Downlink ConfigurationsG1 BTS Coupling Unit The following four figures show the possible G1 BTSMark2 Coupling Unit downlink configurations. These show the maximumnumber of carriers that each configuration can use.

The following figure shows a G1 BTS Mark2 two-carrier downlink Coupling Unit.

RF Self−test

Transmitter 1

Transmitter 2

FBC2 or CBC2

TransmitAntenna

Figure 27: G1 BTS Mark2 Two-carrier Downlink Coupling Unit

The following figure shows the possible G1 BTS Mark2 four-carrier downlinkcoupling unit variants.

RF Self−testFBC2

Transmitter 1

Transmitter 2

Transmitter 4

RF Self−testCBC4

Transmitter 1

Transmitter 2Transmitter 3

Transmitter 4

Transmit Antenna

Transmit Antenna

Transmitter 3FCAV

Figure 28: G1 BTS Mark2 Four-carrier Downlink Coupling Unit Variants

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The following figure shows the two possible G1 BTS Mark2 six-carrier downlinkcoupling unit variants.

Transmit Antenna

RF Self−test

FCAV

FEC2

Transmitter 1

Transmitter 2

Transmitter 3

Transmitter 4

Transmitter 5

Transmitter 6

Transmit Antenna

CBC4

CEC2

Transmitter 1

Transmitter 2

Transmitter 4

Transmitter 5

Transmitter 6

Transmitter 3

FBC2

RF Self−test

Figure 29: G1 BTS Mark2 Six-carrier Downlink Coupling Unit Variants

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The following figure shows the two possible G1 BTS Mark2 eight-carrierdownlink coupling unit variant.

RF Self−testFBC2

FCAV

FEC2

FEC2

Transmitter 1

Transmitter 2

Transmitter 3

Transmitter 4

Transmitter 5

Transmitter 6

Transmitter 7

Transmitter 8

RF Self−testCBC4

CEC4

Transmitter 1




Transmitter 8

Transmit Antenna

Transmit Antenna

Figure 30: G1 BTS Mark2 Eight-carrier Downlink Coupling Unit Variants

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G2 BTS Coupling Unit The following five figures show the possible G2 BTSCoupling Unit downlink configurations.

The following figure shows the two possible G2 BTS single-carrier downlinkcoupling unit variants.

RF Self−test

RF Self−testFront−End

WB1GorWB2GorWB2D

DUPGor DUPD or DUD2

TransmitAntenna

Transmitter

Transmitter

TransmitAntenna

Figure 31: G2 BTS Single-carrier Downlink Coupling Unit Variants

The following figure shows the three possible G2 BTS two-carrier downlinkcoupling unit variants.

RF Self−testTransmitter 2

RF Self−test


Front−End


Front−End

WB2Gor WB2D

DUD2

Transmit Antenna

Transmitter 1

Transmit Antenna

Transmit Antenna

Transmit Antenna

RF Self−test

DUPG or DUPD

Figure 32: G2 BTS Two-carrier Downlink Coupling Unit Variants

The following figure shows the two possible G2 BTS three- to four-carrierdownlink coupling unit variants.

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Transmitter 2

Front−End

RF Self−test

DUD2

Transmitter 2

Front−End

RF Self−test

DUD2

Transmitter 3

Transmitter 4

DUPG orDUPD

DUPG or DUPD

Transmit Antenna

Transmit Antenna

Transmit Antenna

Transmit Antenna

Transmit Antenna

Front−End(Diversity)

Transmit Antenna

Transmitter 1

Transmitter 3

Transmitter 4

Transmitter 1

RF Self−test

RF Self−test

Front−End(Diversity)

Figure 33: G2 BTS Three to Four-carrier Downlink Coupling Unit Variants

The following figure shows the G2 BTS single to four-carrier downlink couplingunit.

RF Self−test

Transmitter 1


Transmitter 4

FRBGorCRBGorRC4D or RC8D

TransmitAntenna

Figure 34: G2 BTS Single to Four-carrier Downlink Coupling Unit

The following figure shows the G2 BTS single to eight-carrier downlink couplingunit.

RF Self−test

Transmitter 1

Transmitter 2

Transmitter 8

FRBG/FREGorCRBG/CREGorRC8D

TransmitAntenna

Figure 35: G2 BTS Single to Eight-carrier Downlink Coupling Unit

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8.5.5.4 Uplink ConfigurationsG1 BTS Coupling Unit The following four figures show the possible G1 BTSMark2 Coupling Unit uplink configurations.

The following figure shows the three possible G1 BTS Mark2 non-diversity, twoto four-carrier uplink coupling unit variants.

Receiver 1

RF Self−test RXFE

Receiver 4

RTSERTMA

Long RFCable

RF Self−test

Receiver 1

MCEX

CRFERF Self−test

Receiver 1

Receiver 4

ReceiveAntenna

Receive Antenna

Antenna

Receiver 4

Receive

MCEX

Figure 36: G1 BTS Mark2 Two to Four-carrier Uplink Coupling Unit Variants

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The following figure shows the three possible G1 BTS Mark2 diversity, two tofour-carrier uplink coupling unit variants.

RF Self−test

RXDE

Receiver 1

MCEX

MCEX

Receiver 4

RTDE

RTMA

RTMA

RF Self−test

Receiver 1

MCEX

MCEX

Receiver 4

CRDE

RF Self−test

Receiver 1

Receiver 4

Receiver 1

Receiver 4

Receive Antenna

4−way Splitter

4−way Splitter

Receiver 1 (Diversity)


Receive Antenna (Diversity)

Receive Antenna


Long RF Cable

Long RF Cable

4−way Splitter

4−way Splitter

Receiver 1 (diversity)


Receive Antenna


4−way Splitter

4−way Splitter

Figure 37: G1 BTS Mark2 Two to Four-carrier Diversity Uplink Coupling UnitVariants

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The following figure shows the three possible G1 BTS Mark2 non-diversity,six to eight-carrier uplink Coupling Unit variants.

MCEX

MCEX

RXFERF Self−test

Receiver 1

Receiver 8

CRFERF Self−test

Receiver 1

Receiver 8

MCEX

MCEX

RTSERTMA

RF Self−test

Receiver 1

Receiver 8

Receive Antenna

Receive Antenna

Receive Antenna

Long RF Cable

Figure 38: G1 BTS Six to Eight-carrier Uplink Coupling Unit Variants

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The following figure shows the possible G1 BTS Mark2 diversity, six toeight-carrier uplink Coupling Unit variants.

MCEX

MCEX

MCEX

MCEX

RF Self−test

RXDE

Receiver 1

Receiver 8

Receiver 1

Receiver 8

CRDE

RF Self−test

Receiver 1

Receiver 8

Receiver 1

Receiver 8

MCEX

MCEX

RTDE

MCEX

MCEXRTMA

RTMA

RF Self−test

Receiver 1

Receiver 8

Receiver 1

Receiver 8

Receive Antenna


Receive Antenna


Receive Antenna


Long RF Cable

Long RF Cable

4−way Splitter

4−way Splitter

8−way Splitter

8−way Splitter

4−way Splitter

4−way Splitter

Figure 39: G1 BTS Mark2 Six to Eight-carrier Diversity Uplink Coupling UnitVariants

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8.5.5.5 G2 BTS Coupling UnitThe following three figures show the possible G2 BTS Coupling Unit uplinkfuncitons.

The following figure shows the G2 BTS single/two-carrier uplink coupling unit.

RF Self−test

Receiver 1

Receiver 2

Receiver 1

Receiver 2

FEG2 or FED2

FEG2 or FED2

Receive Antenna or Duplexer


Figure 40: G2 BTS Single/Two-carrier Uplink Coupling Unit

The following figure shows the G2 BTS single to four-carrier uplink coupling unit.

RF Self−test

Receiver 1

Receiver 1

Receiver 2

Receiver 3

Receiver 4

Receiver 2

Receiver 3

Receiver 4

FEG8 or FED8

FEG8 or FED8

Receive Antenna or Duplexer

Receive Antenna (Diversity) or Duplexer

Figure 41: G2 BTS Single to Four-carrier Uplink Coupling Unit

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The following figure shows the two possible G2 BTS single to eight-carrieruplink coupling unit variants.

RF Self−test

Receiver 1

Receiver 2

Receiver 8Receiver 1Receiver 2

Receiver 8

RF Self−test

Receiver 2Receiver 1

Receiver 8

Receiver 2Receiver 1

Receiver 8

Receive Antenna

FEG8 or FED8

FEG8 or FED8


Receive Antenna


TMAG or TMAD

Long RF Cable

RMCG or RMCD

TMAG or TMAD

Long RF Cable

RMCG or RMCD

Figure 42: G2 BTS Single to Eight-carrier Uplink Coupling Unit Variants

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9 Software

9 Software

This chapter describes the BTS software. After providing a general overview, itdescribes the:

Definition of firmware and software

Software configuration data

BTS Start-up and initialization

O&M Software

Frame Unit Software

Carrier Unit Software.

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9 Software

9.1 Overview on SoftwareMany BTS functions are realized or controlled by microprocessors usingassociated code. This code is the BTS software.

The BTS software provides services to Layers 1 - 5 in the ISO OSI referencemodel.

The BTS software is responsible for:

Initializing, configuring andsupervising the BTS

Software for this purpose comes under the general categoryof O&M. O&Mfunctions monitor and control the correct operation of the BTS and itsexternal interfaces. O&M software therefore supports functions for:

Configuration management

Fault management

Performance management.

Realizing the BTS operational functions

The operational software supports a reliable two-way communications pathbetween the land-based network and Mobile Stations. This path is ’open’to traffic and signalling meeting GSM standards. For the purpose of thisdescription, operational software falls into two primary categories:

Telecommunications functions

Transmission functions.

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9 Software

9.2 Software and FirmwareThe BTS uses code permanently resident in the units concerned, and codedownloaded after reset or startup. To distinguish between these categories,resident software is referred to as firmware.

9.2.1 Firmware

Firmware is held in a non-volatile ROM on the unit. It is typically associatedwith low-level functions such as self-testing or communication control. Asresident software, it also includes the bootstrap software that performs the initialboot-up sequence. This establishes input -output mechanisms which allowsaccess to downloadable software.

9.2.2 Downloaded Software

The BTS downloads software from the BSC, under firmware control.Downloaded software typically provides high-level functions such as trafficmanagement or database maintenance.

9.2.3 Software/Firmware Usage

The following table shows the split between firmware and software.

BTS Firmware Only Software and Firmware

Station Unit (ExternalAlarm Connection, Timingand Switching)

Station Unit (OMU)

- Frame Unit

Carrier Unit -

G1/G2 BTS

Coupling Unit RemotelyTunable Combiner

-

Table 27: BTS Firmware/Software Split

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9.3 Software Configuration DataTo define the way in which the BTS functions and system control areimplemented, the microprocessor code is supplied with software configurationdata. This data is held in configuration files that are downloaded at start-up orreset.

The configuration data can therefore be changed only when restarting theassociated function.

The relationship between the software and data files downloaded to the BTS isshown in the following table.

BTS UnitBootstrapSoftware Firmware

OperationalSoftware

LoadableSoftware

Loadable DataFiles

Station UnitOperations &MaintenanceUnit (OMU)

NONVOL NONVOL VOL OMU-SW

FU-SCP-SW

FU-MFP-SW

FUE-SW

BTS-MF

OMU-CPF

OMU-SPF

FU-CPF

Staion UnitTimingGeneration

NONVOL NONVOL - - -

Station UnitExternal Alarm

NONVOL NONVOL - - -

Frame UnitMulti-board

NONVOL NONVOL VOL FU-SCP-SW

FU-MFP-SW

FUE-SW

FU-CPF

Frame UnitSingle-boardDRFU

NONVOL NONVOL VOL DR-LD-FW

DR-SCP-SW

DR-MFP-SW

DR-TMUX-SW

DR-BED-SW

DR-ENC-SW

DR-DEC-SW

DR-DEM-SW

FU-CPF

Carrier Unit NONVOL NONVOL - - -

G1/G2BTS

Coupling UnitRTC

NONVOL NONVOL - - -

Table 28: Software and Data Held by BTS

Abbreviations used in this table: NONVOL - Non Volatile VOL - Volatile

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9.4 BTS Start-up and InitializationWhen the BTS is powered-up or reset, a fixed sequence of events occurs.

1. Start-up firmware is executed, including self-tests.

2. Software is downloaded from the BSC.

3. Functions are initialized and software is activated.

The following sections describe these events.

9.4.1 Start-up Firmware

After power-up or reset, the OMU, Frame Unit and all units connected via theDCL2 (for the G1/G2 BTS) start their firmware. This executes self-test functionsin each unit. The OMU then runs boot procedures to start the operatingsystem and interface control code.

The following figure shows the sequence of events.

OMU Frame Unit DCL2/ECPL UnitsBSC

Report OMU Started

Acknowledge

Micro−BTS Power−up

Software and DatabaseDownload

Report Start−up Results to BSC

Activate Software/Firmware of Each Unit

Time

Load Frame Unit

Load Carrier Unit

* LAPD Link Established

Software

Software**

* LAPD Link Access Procedure on the D Channel** Only for Micro−BTS

ExecuteSelf−tests

ExecuteSelf−tests

ExecuteSelf−tests

Configure UnitsCollect Start−up Results

StartBoot Fimware

Figure 43: BTS Start-Up Sequence

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9.4.2 BTS Download

When the OMU self-tests are successfully completed, the BSC establishes theOML between the BSC and the OMU. This uses the LAPD protocol.

Once the OML is running, the OMU sends an ’OMU Started’ message tothe BSC. The BSC then begins the software download to the OMU over theLAPD connection.

The software download comprises:

Software for the OMU (including database)

Software for the Frame Unit functions

Hardware and software configuration files.

The BSC transfers the BTS software package to the OMU as a set of files.First, the BSC sends a list of all the files needed by the BTS concerned. TheOMU then requests these files from the BSC.

The first file transferred in the main download is the OMU software, followed bythe OMU software configuration parameter files. The OMU software is thenexecuted, and the Frame Unit software files are downloaded.

The Frame Unit files contain the Frame Unit operational software andconfiguration files. The files are temporarily stored in the OMU RAM. Thedownload ends with the transfer of O&M configuration parameter files.

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9.4.3 BTS Initialization

When the BTS download is complete, the OMU collects all unit start-up testresults. The OMU then configures each of the units and functions as shown inthe following table.

Units and functionsto be initialized G1/G2 BTS

Frame Unit Each Frame Unit is configured by downloading operational software and aconfiguration data file from the OMU to the Frame Unit. The OMU initiates thedownload by sending a ’Load Frame Unit Software’ message. This instructs theFrame Unit to handle the transfer. The Frame Unit software is then downloaded.The Carrier Unit software is stored in the Frame Unit RAM, and is passed to theCarrier Unit later, via the DCL2/ECPL.

Files are sent to the Frame Unit in fixed-length packets. The Frame Unit calculateschecksums to verify the integrity of the data received. When the operationalsoftware has been loaded, the OMU sends an ’End Frame Unit Download’message. This is followed by the Frame Unit Configuration Parameter file. TheFrame Unit is then initialized.

After Frame Unit initialization, the RSL is established between the Frame Unitand the BSC, using the LAPD protocol. Telecommunication function messagesare exchanged over the RSL.

Master Clock Control In a master BTS, the redundant Master Clocks are initialized independently. Bothare subsequently synchronized, then designated as main and standby.

Slave BTSs are provided with clock signals from the master BTS, to which therepeater functions of the slave BTS are synchronized. The OMU is informed ofthe success/failure of the initilaization.

Carrier Unit Initialization of the Carrier Unit is supervised by the OMU, which applies a numberof checks to verify that the start-up sequence has been successful.

The OMU then queries the type of Carrier Unit in use, since this can affect theconfiguration parameters which are subsequently downloaded.

External AlarmConnection Function

The OMU sends the External Alarm Connection function a list of settings for theInput/Output ports. Port registers are initialized accordingly and then checkedagainst the configuration file. A timeout is applied for the completion of the start-upprocedures.

Frequency HoppingFunction

Initialization of the Frequency Hopping function is monitored by the OMU to ensurethat the start-up sequence has been successful. The Frequency Hopping functionthen identifies the type of hardware in use, and the OMU sends an oppropriateconfiguration message. This defines the Freuqency Hopping behavior required.

BCCH-Carrier Switch The OMU ensures that the BCCH-Carrier Switch is set to the correct position forthe configuration.

RTC The RTC is initialized by the OMU. The OMU checks if retuning is required tomatch the input frequencies to the outputs of the associated Carrier Units. If tuningis required, the Carrier Units are switched off and the RTC inputs are retunedusing stepper motors. When tuning is complete, the Carrier Units are switched on.

Receiver Front-endFunction

The Receiver Front-end function may, or may not, require initialization. Thisdepends on type, and whether or not antenna diversity is used. Redundancyconfiguration is initialized where appropriate. In all cases a status check isperformed.

Table 29: BTS Initialization, Units and Functions to be Initialized

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9.5 O&M SoftwareThe O&M software manages the BTS O&M procedures. These procedurescan be described as:

Functions

Software Modules.

9.5.1 Functions

The O&M software performs the following functions:

BTS equipment configuration

Frame Unit software download and initialization

Cyclic equipment supervision

Status reporting to the BSC

BTS alarm processing

Local failure recovery handling.

With the exception of one communication handler (for the Q1 Node), all O&Msoftware runs on the OMU.

At power-up or reset, the following sequence occurs:

1. The BSC downloads the O&M operational software.

2. The BTS hardware is initialized and software is downloaded to the FrameUnit.

3. The BTS functions are started.

4. When the BTS is operational, the OMU collects alarms from the Frame Unitand the ECPL Layer 1 entities. The OMU filters the alarms and tries toimplement recovery actions. If no recovery is possible, the OMU sendsappropriate alarms to the BSC.

The SCP provides the Q1 Node function. This supervises the Layer 1 entities,and indicates any problems to the OMU.

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9.5.2 Software Modules

The O&M software is split into a number of modules:

Root System

Application Functions

Support Functions

Interface Handlers

Q1 Node Handler.

Each module contains one or more tasks, the scheduling of which is managedby a pre-emptive operating system.

9.5.2.1 Root SystemThe Root System is executed once software downloading is complete. Itperforms the following procedures:

Creation and initialization of operating system resources.

Initiation of all tasks for execution under operating system control.

Download of data files.

Initialization of data areas (using BSC configuration data).

Once the execution of root software is complete, the other software modulesstart.

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9.5.2.2 Application FunctionsThe application functions shown in the following table perform the primaryOMU processing.

Fuction Description

Initialize BTSModule

The Initialize BTS module initializes and configures each individual BTS unit.

CommandHandler

The Command Handler provides unit-based handling of BTS O&M procedures.

The Command Handler processes commands from the Initialize BTS, ConfigurationHandler and Central Command Controller modules. It translates the commands from afunction-related form, into a sequence of unit-based O&M actions. The associated unitsthen initiate these actions.

CentralCommandController

The Central Command Controller handles function-related operations.

Whenever an operational command is entered or an alarm is received, the CentralCommand Controller triggers appropriate actions. The OMU sends messages to theCommand Handler to perform any actions required. Function-related information in thedatabase is updated accordingly.

ConfigurationHandler

The Configuration Handler manages reconfiguration operations.

Whenever a reconfiguration command is received, the Configuration Handler generatesa sequence of function-related messages. These are sent to the Command Handler toperform the required reconfiguration actions. The database is updated accordingly.

AlarmTranslator

Alarm messages from the BTS units (in unit-based format) are passed to the AlarmTranslator module via DCL1 or DCL2 and the SCP Q1 Node.

Each alarm is translated to a ’raw alarm message’ and then stored in the OMU database.All alarms are sent to the Alarm Handler for processing.

AlarmHandler

The Alarm Handler is responsible for alarm filtering, alarms correlation and BTS faultlocalization.

Certain fault conditions can cause false alarms to be reported by indirectly affected units.Alarms which can be provoked in this way must be correlated to determine the true causeof the fault, before any action is taken.

Alarms that pass the filtering and correlation process are reported to the BSC. Theappropriate maintenance actions are then initiated via the Central Command Controller.

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Fuction Description

StatusReportingModule

The Status Reporting Module supplies database information to the BSC and operator.

On request, the module scans the OMU database and formats the required information,before forwarding it to the BSC or BTS Terminal.

AuditManager

n addition to the databases held by each BTS OMU, the controlling BSC also holds abackup database. This contains function-related information for all of its BTSs.

In order to provide effective backup, the contents of the BSC database must be consistentwith the OMU databases. The OMU can itself request an audit following configurationfailure, recovery failure, or if an OMU fault occurs. At the OMU, this checking procedure ishandled by the Audit Manager.

If differences are found, the database(s) are corrected and fault recovery is initiated ifnecessary/possible.

Table 30: O&M Software, Application Functions

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9.5.2.3 Support FunctionsSupport functions provide general facilities that are used by more than onetask. There are many groups of these including:

Database manipulation

Function-related data manipulation

Unit-related data manipulation

Message assembly, format checking, etc.

Time supervision.

Of particular importance are the:

OMU database

It contains information on the whole BTS including its Hardware/software

inventory, Configuration and Status.

Information in the database is held in both function-related (hardwaregeneration independent), and unit-related (hardware specific) forms. The

hierarchical relationships between the functions/units are also held.

The OMU database does not run as a task. Access is provided through a

suite of functions that can be called by any of the OMU tasks.

Message Route functions

The Message Router provides a flexible mechanism for the internal

distribution of messages. This avoids the need for hard-coded messagedistribution in each task.

Each task sends a ’message table’ to the Message Router. This contains

a distribution list for each message type the task issues, and a receptionlist detailing the message types the task wants to receive.

When a task wants to send a message to another task, it sends themessage to the Message Router. The Router distributes the message to

tasks in the appropriate distribution list, if they are flagged to receivethat message type.

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9.5.2.4 Interface HandlersA number of Interface Handler modules as shown in the following table managethe communication between BTS entities.


DCL1 The DCL1 communication code is divided into OSI Layers 2, 3and 4. Layer 2 is sub-divided into two sub-layers:

MAC packet-level transfer sub-layer

LLC acknowledged connectionless service (LLC type 3)

sub-layer.

DCL1 Layer 3 code performs message format and translationfunctions. It is also responsible for the periodic status pollingof the Frame Unit. Layer 4 code handles software downloadto the Frame Unit.

DCL2 DCL2 communication is organized in a half-duplex master-slavearrangement. The master sends command messages tonumbered slave(s), which reply when a command is received. Aslave cannot begin transmission without receiving a command.

DCL2 participates in exchanges at Layers 2, 3 and 4. Theselayers are all handled by a single module. This interfaces theupper layers and the single byte frames used on the physicalconnection. DCL2 responsibilities include status polling carriedout for the OMU. The physical layer monitors for reception errorsand operates timeout checking.

OML The OML communication operates in two modes. These are for:

Software Download

Alarm and message transfer between the BSC and the OMU.

OML Layer 2 code employs LAPD signalling. Layer 3 codeconverts data between the OMU internal format and the GSMframe format used on the OML.

MMI The MMI enables a local BTS Terminal to be connected to theOMU. This allows test results, status and alarm information to beaccessed by the operator. In addition, service commands canbe issued such as ’Initialize’ or ’Disable’ particular equipment.

The MMI uses a full-duplex RS-232 link. The BTS Terminal isa personal computer which runs special application software tocommunicate with the OMU.

Table 31: O&M Software, Interface Handlers

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9.6 Frame Unit SoftwareThe Frame Unit software provides control and baseband data processing,corresponding to Layers 1 to 3 in the OSI 7-Layer communications model.

The software is split into the following components:

SCP Control Functions

MFP Control Functions

Encoder

Demodulator and Channel Decoder.

Further control software supervises the generation of timing signals.

9.6.1 SCP Control Functions

The SCP software handles O&M and telecommunications procedures. Theseprocedures can be described as:

Functions

Software modules.

9.6.1.1 FunctionsThe SCP functions are:

O&M functions:

Frame Unit tests

SCP software downloading

Frame Unit and Carrier Unit software downloading

Management of configuration parameters

Management of reconfiguration parameters

Software integrity verification

Control of Frame Unit mode of operation

Supervision and fault management

LAPD link supervision

Processor overload supervision

RACH load measurements.

Telecommunications functions:

LAPD protocol handling

LAPDm protocol handling

Layer 3 protocol handling

Telecommunication configuration message processing

Radio Channel management

Error handling of telecommunications software.

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9.6.1.2 Software ModulesThe SCP software is split into a number of modules:

Root System


Interface Handlers.

Each module contains one or more tasks. The scheduling of these tasks ismanaged by a pre-emptive operating system.

9.6.2 MFP Control Functions

The MFP is the physical interface between the SCP and the Layer 1 entities.The MFP software handles the low-level O&M and telecommunicationsprocedures under control of the SCP. These procedures are:

Functions

Software modules.

9.6.2.1 FunctionsThe MFP functions are:

O&M functions:

Managing the initialization and configuration of the Layer 1 entities.

Supervising the external interfaces (fault management).

Supervising the Layer 1 entities (hardware and software failure).

Managing the exchange of messages between the SCP and Frame Unit

and Carrier Unit entities.

Telecommunications functions:

Managing the synchronization (frame number).

Managing the multiframe configuration.

Routing the telecommunications messages.

9.6.2.2 Software ModulesThe MFP software is split into a number of modules:

Root System


Interface Handlers.

Each module contains one or more tasks. The scheduling of these tasks ismanaged by a pre-emptive operating system.

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9.6.3 Software States of the Control Functions

The SCP and MFP functions are implemented as a FSM, with six primarystates described in the following table.

State Description

Power Off In the Power Off state no internal functions are available.

Initialization The SCP operates under control of the OMU. During Initialization, which follows power-upor reset, the SCP performs self-tests and attempts to communicate with the OMU. If this issuccessful, it then initializes the MFP which performs its own self-tests and communicatesthe results to the SCP.

When both subsystems are initialized, the SCP determines the status of the Frame Unit,including all entities.

Initialization is completed when the SCP configures the MFP and all the Layer 1 Entities.The Frame Unit is now ready to begin operational processing.

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State Description

The SCP and MFP enter their Operational states following successful initialization.

In this state the principal task of the SCP is to activate, manage and deactivate thechannels. These functions are performed under BSC control.

SCP operational tasks also involve exchanges of information with the OMU that relate to:

Alarm reports

Configuration/reconfiguration

MFP debugging interface

Supervision of the Frame Unit status.

Frame Unit supervision detects faults in the Frame Unit itself, or in other BTS equipmentthat has an impact on the Frame Unit.

In the Operational state, the MFP is primarily responsible for managing the multiframes fordifferent configurations of the radio channels. This task consists of:

Obtaining configuration details from the SCP

Sending this information to the Encoder or Channel Decoder, and to the Demodulator.This must be done early enough to allow these entities to perform the right action at

the right time.

Other MFP functions include message routing between the SCP and the Layer 1 Entities.

Operational

These messages form an essential part of the following functions:

Routing transcoder alignment message from the Encoder to the Channel Decoder

Handling channel configuration messages during handover procedures

Synchronizing the MFP and Layer 1 Entities

Monitoring the interface.

Abnormal behavior in the Operational state triggers alarms that can be classified as follows:

Fatal alarms; the Frame Unit cannot handle BTS to Mobile Station communications

Non-Fatal alarms; the Frame Unit can handle BTS to Mobile Station communications ina degraded mode.

The MFP warns the SCP of all detected alarms.

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State Description

FaultLocalization

The Fault Localization state is entered from the Operational state following the detection ofa fatal incident and from any state after a reset.

Non-fatal alarms are reported by a message to the OMU.

In the case of a fatal alarm (i.e., due to hardware), the MFP stops its own processing andwaits to be restarted by the SCP.

In the case of a fatal error (i.e., due to software or protocol), the MFP stops its processingand stores the cause of the error.

For both hardware and software errors, when the MFP is restarted by the SCP it indicatesthe cause of the problem. Localization is therefore always reported at the level of BTS, anda limited recovery strategy is available. First, a restart is attempted. If this is unsuccessful,the OMU commands a reset. If this fails, the RA SBL is set to FOS. The OMU thenactivates an Frame Unit reset.

Out of Order The Out of Order state is entered if a fatal failure is detected or when a software downloador reconfiguration fails.

No supervision is performed in this state, so the Frame Unit can exit the state only as theresult of an external event. The SCP therefore requests a reset from the OMU.

Standby The Standby state is entered from the Fault Localization state if fatal external link failuresare detected. On removal of the fault, the Frame Unit initiates its own recovery andinforms the OMU.

Table 32: SCP and MFP Functions, States of the FSM

9.6.4 Encoder

The Encoder implements the following primary funcitons:

BSI time slot management

Rate Adaptation for the data and speech traffic channels

Transcoder time alignment

FACCH bit stealing

Channel encoding and burst building

Burst control

Transmitter power control

Encryption.

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9.6.5 Demodulator and Channel Decoder

The Demodulator and Channel Decoder each require dedicated software.

9.6.5.1 DemodulatorThe Demodulator processes the physical channels received from the BBI onthe uplink, and passess the processed data to the Channel Decoder. The datatis recieved from the FHI as complex samples produced by the Carrier Unit.

The Demodulator performs the following functions for each channel:

GMSK demodulation

Carrier frequencies offset compensation, estimation, filtering

Channel impulse response estimation

TOA estimation

Matched filtering

Equalization

Soft decision

Testing.

There is also a Decryption function, which occurs just before the data ispassed to the Channel Decoder. This is performed in the BED, configured bythe Demodulator software.

The MFP uses the ID_CHC messages to send the uplink decryption keys,the decryption flag and the algorithm type flag to the Demodulator. TheDemodulator extract this information, adds the fram number, and sends thecombined data to the BED. Only nomal bursts are decrypted.

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9.6.5.2 Channel DecoderThe Channel Decoder reassembles logical channels from the bursts of datareceived from the Demodulator.

The Channel Decoder identifies bursts using channel configuration messagesreceived from the MFP. The burst process is therefore controlled in real-time,using a special operating system.

During burst processing, the Channel Decoder performs the following functions:

De-interleaving

Burst processing control

Carrier Unit monitoring

TOA filtering

Received signal level filtering

RACH load measurements.

The reassembled blocks are then processed. Block processing involves thefollowing functions:

Convolutional decoding

Block decoding

Bit reordering

Hard decisions of uncoded bits

Received signal quality estimation

Rate adaptation

Building of output frames

Filtering of Layer 2 fill frames

Ciphering state initialization for signalling frames

Indication of valid traffic frame decoding.

The data is then routed towards the BSC.

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9.7 Carrier Unit SoftwareThe Carrier Unit provides an interface between the BTS baseband data and theradio signals used by Mobile Stations. On the downlink, this is achieved bythe transmitter(s), on the uplink by the receiver(s).

9.7.1 Transmitter

The transmitter transforms the digital baseband data sent from the Encoder(transmit data), into a GSM radio signal for the downlink.

G1/G2 BTS The principal tasks of the transmitter firmware are to monitor andcontrol the flow of this data through the various stages used to procedurethe GSM signal.

These functions are sub-divided into:

CUC firmware tasks, including:

Data transfer between Carrier Unit and FHIs

DCL2 communication

Receiver supervision and transfer of received data.

Power Control and Alarms (PCA) firmware tasks, include:

Supervision of transmit data-transfers

Output power control

Status monitoring and alarm generation

Data validity checking.

A watch-dog function resets the transmitter in the event of a firmware crash.

9.7.2 Receiver

The receiver transforms radio signals received via the Air Interface, to an analogbaseband signal. This is then sampled to produce a digital representation thatis sent to the Frame Unit for demodulation and further processing.

These tasks are logically and physically divided into two parts:

Analog receiver

Digital receiver.

9.7.2.1 Analog ReceiverThe analog part of the receiver operates under control of the transmitterprocessor and digital receiver part. It performs the following functions:

Low noise amplification

Down conversion

IF filtering

IQ GMSK demodulation and baseband filtering

A-D conversion.

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9.7.2.2 Digital ReceiverThe digital part of the receiver monitors and controls the signal processing. Inaddition, it optimizes the performance of the analog part of the receiver.

From the A-D converter, the uplink data stream is divided into blocks, eachblock corresponding to a time slot. The Data Input and Data Processingfunctions, to which the blocks are subjected, run as a continuous loop operatingon one data block per loop, as shown in the following table.

Function Description

Data Input As the A-D converter finishes each conversion, it sends an interrupt to the processor.The processor then transfers the data from the A-D vonverter to an internal memorybuffer.

Data Processing The data read from the A-D converter for each time slot is pre -processed to allow itssubsequent demodulation. Data output for each time slot occurs at the beginning ofthe next time slot. The data output for each time slot is checked for inconsistencies thatcan indicate an error. Each sample is taken from a buffer and processed as follows:

DC OffsetCalculation

A DC offset is calculated to counteract DC variations in the D-Aconverter and other analog hardware. This value is subtracted fromall samples in each time slot.

PowerCalculationand PathSelection

The receiver provides the alternatives of high and low gain signalpath. This allows wide variations in received signal strength to beaccommodated. The signal power of the I and Q components atthe output of each signal path is calculated. This is done for eachindividual time slot. The results are used to select the output from thehigh or low gain reicever path for further processing.

RSSI RSSI is based on the power input level measured at the antennaconnector. The RSSI value is used by the BSC to calculate theoptimum RF power level for the Mobile Station.

Scaling FactorCalculation

The receiver A-D converter produces 12-bit data. From this, only8-bits representing the most significant part of the signal are required.These are calculated by multiplying samples from the selected signalpath by a coefficient. The coefficient is inversely proportional to thereceived signal strength. This ensures that the samples passed tothe demodulator represent similar amplitudes, regardless of receivedsignal strength.

FrequencyTranslation

To simplify the demodulation in the Frame Unit, the FrequencyTranslation funciton performes initial pre-processing of the signal.This involves multiplying the samples by a complex coefficient.

Fault Checking Ongoing checks are performed for each time slot during operation. These checksverify that data is sent to the uplink Baseband Interface and that data is received fromthe analog part of the receiver. If these tests fail, or if no interrupts are detected, analarm is sent to the MFP.

Table 33: Digital Receiver, Functional Sub-Entities

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10 BTS Objects

This chapter describes the Managed Objects for the BTS. It provides theallowed states for both managed objects and SBLs. It maps managed objectsand SBLs to the corresponding RIT.

It provides for both Managed Objects and SBLs:

Hierarchy

Allowed states

Allowed actions

RITs

Managed Object/SBL to RIT relationships.

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10 BTS Objects

10.1 Managed Objects and SBL DescriptionThe following table describes the BTS Managed Objects and SBLs in terms ofthe functions:

Telecom

O&M

Hardware mapping.

ManagedObject SBL Function Description

BTS BTS Telecom None.

O&M Supports all configuration management actions performed on BTSequipment.

The SBL also collects general BTS alarms (e.g., loss of Q1 orToken Bus).

HardwareMapping

BTS equipment.

CCF CCF Telecom None.

O&M Cools down the BTS boards to maintain them within theirenvironmental temperature range.

HardwareMapping

BTS cooling fans equipment.

CLLK CLLK Telecom None.

O&M Provides the whole BTS with four clocks signals derived from the13 Mhz master frequency. Those signals are delivered via a bustype link to the frame units, the carrier units and the frequencyhopping units.

The clock signals are the basic timing for TDMA.

HardwareMapping

Frequency generator and clock distribution units.

CU CU Telecom Transforms a baseband signal into an UHF signal on thetransmitting side and vice versa on the receiving side. The UHFvalue is configured by the OMU/SUM from an OMC-R command.

The SBL also measures the strength of the received signal.

O&M Measures regularly the VSWR. When the VSWR is too high, itautomatically disconnects the transmitter.

HardwareMapping

Carrier Units (transmitter/receiver boards and power sources).

A transmitter/receiver board contains the GSM/DCS modulator,UHF up/down converter and amplifiers.

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EACB EACB Telecom None.

O&M Performs the following actions:

Sends to the OMU/SUM environmental alarms such as fire,

smoke, intrusion, overheating, etc

Commands the shutdown or activation of the BTS powersupplies

Switches the BCCH to the spare combiner

Triggers the change-over to the redundant amplifier

Distributes the Q1 bus to the carrier units and to the extensioncabinets of the BTS.

HardwareMapping

EACB equipment.

FHU FHU Telecom Switches each time slot of a TDMA frame between the FUs andthe CUs tuned to different frequencies, according to a frequencyhopping algorithm.

O&M None.

HardwareMapping

FHU

FU FU Telecom Handles the following layers:

Layer 1 - the electrical interface from the CU as well as the 2

Mbps interface from the Abis interface

Layer 2 - the LAPD and LAPDm protocols

Layer 3 - part of the RR signaling from mobile side RSL.

O&M For a specified time slot it:

Provides configuration parameters

Computes online the results of the FU-CU loop test

Computes (on triggered basis) the results of the radio loop test

Performs measurements (processor load, interference level,etc.).

HardwareMapping

FU boards

FU_TS Telecom None.

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O&M Addresses a particular baseband channel of the FU particularly forconfiguration purposes.

Performs RTE loop test on addressed baseband channels.

HardwareMapping

None.

OMU OMU Telecom None.

O&M Main functions are:

Initializes and configures the BTS

Collects and reports alarms to the BSC

Transfers SW and data files to the FUs

Triggers the BTS channels configuration in case of a failure

Tests triggering at the other parts of the BTS

Communicates with local terminal.

HardwareMapping

OMU/SUM board

RA RA Telecom Models the up and down interface to the transmit/receive antennae.

Receive:

Filters the signal from the antennae to remove unwanted

signals outside the GSM band

Amplifies the filtered signal

Performs signal splitting by multi-coupling to allow each

receiver to pick up its own signal.

Transmit:

Couples to the transmitting antennae all analog signals comingfrom the carrier units.

Optionally, it is also able to switch the BCCH carrier unit to a

spare combiner, on an OMU/SUM command.

O&M Tunes the cavities if RTCs are used.

Measures the VSWR regularly.

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HardwareMapping

Receiver Front-End

FU power supplies

CU power supplies

Transmission combiners rack (cavities + cabling)

BCCH switch.

RTE Telecom None.

O&M Loops the RF signal of a specified time slot from the transmittingend to the receiving end.

Activates the connection between the transmitter combiner andthe receiver front end input under the control of the OMU/SUM.

HardwareMapping

RTE

Table 34: BTS Managed Object and SBL Descriptions

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10.2 BTS SBLsThe following tables list the Managed Objects and SBLs for the G1 BTS Mark 2,and G2 BTS.

Managed Object SBL Type Description

BTS BTS Base Transceiver Station

CCF CCF Cabinet Cooling Fan

CLLK CLLK Clock Link

CU CU Carrier Unit

EACB EACB External Alarm Collection Board

FHU FHU Frequency Hopping Unit

FU FU Frame Unit

- FU_TS Frame Unit Time Slot

OMU OMU Operations and Maintenance Unit

RA RA Radio Access

- RTE Radio Test Equipment

Table 35: G1 BTS and G2 BTS Managed Objects and SBLs

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10.3 BTS Managed Object (SBL) HierarchyThe Managed Object (SBL) hierarchy reported by the BTS to the OMC-R isshown in the following figures. All Managed Objects (SBLs) are reported by theOMU/SUM except the FU_TS, which is not reported in hardware configurationdata. In addition to the Managed Object (SBL) hierarchy within the BTS, theOMU/SUM also reports to the OMC-R the following information:

Relationship between Frame Unit and LAPD - RSL. It indicates the TEI valueused by the Frame Unit

The relationship between OMU and LAPD - OMU, by indicating the

corresponding TEI value (always 1)

RA configuration parameters, such as type of combiners and BTS powerclass

BTS configuration (Master BTS/Slave BTS)

BTS hardware family (G1 BTS Mark 2 and G2 BTS).

Note: The following SBL hierarchies show only those SBLs reported to the OMC-R.

123456123456123456123456

123456123456123456123456

1234567123456712345671234567

123412341234

123456123456123456123456

CCF* EACB*

FU* CU*

RTE

FU−TS*

RA

OR

OR

CLLK1 CLLK2OMU

FHU 2

BTS

*: means that the box represents several instances of the SBL.

FHU 1

Figure 44: G1 BTS and G2 BTS Managed Object (SBL) Hierarchy Reported bythe OMU/SUM to the OMC-R

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10.4 Allowed Managed Object and SBL States of the G1 BTSMark 2 and G2 BTS

The allowed states for Managed Objects and SBLs of the G1 BTS and G2 BTSare shown in the following tables.

There is no Managed Object eqivalent to the SBL state NEQ.

10.4.1 Allowed States of Managed Object Abis_PCM (SBL Abis-HWAY-TP)

SBL Admin. State Operat. State Availab. State Control State

IT Unlocked Enabled - -

FIT Unlocked Enabled Degraded -

FLT Unlocked Disabled Failed -

EF Unlocked Disabled Dependency/failed -

MSA Unlocked No change - Suspended

Table 36: Allowed States of Managed Object Abis_PCM (SBL Abis-HWAY-TP)

10.4.2 Allowed States of Managed Object (SBL) BTS




MSD Unlocked No change - Suspended


Table 37: Allowed States of Managed Object (SBL) BTS

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10.4.3 Allowed States of Managed Object (SBL) CCF




OPR Locked No change - -



NEQ - - - -

Table 38: Allowed States of Managed Object (SBL) CCF

10.4.4 Allowed States of Managed Object (SBL) CLLK





FOS Unlocked Disabled Off-Line/Disabled -




NEQ (1) - - - -

Table 39: Allowed States of Managed Object (SBL) CLLK

(1) The NEQ state is only allowed for the FHU and CLLK SBLs for specificG2 BTS configurations, where non-redundancy is implemented. The state isnot permitted for G1 BTS Mark 2 configurations.

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10.4.5 Allowed States of Managed Object (SBL) CU




SOS Unlocked Disabled Dependency -





NEQ - - - -

Table 40: Allowed States of Managed Object (SBL) CU

10.4.6 Allowed States of Managed Object (SBL) EACB






NEQ - - - -

Table 41: Allowed States of Managed Object (SBL) EACB

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10.4.7 Allowed States of Managed Object (SBL) FHU









NEQ (1) - - - -

Table 42: Allowed States of Managed Object (SBL) FHU

(1) The NEQ state is only allowed for the FHU and CLLK SBLs for specificG2 BTS configurations, where non-redundancy is implemented. The state isnot permitted for G1 BTS Mark 2 configurations.

10.4.8 Allowed States of Managed Object (SBL) FU










NEQ - - - -

Table 43: Allowed States of Managed Object (SBL) FU

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10.4.9 Allowed States of SBL FU_TS


IT - - - -

SOS - - - -

MSD - - - -

MSA - - - -

UT - - - -

NEQ - - - -

Table 44: Allowed States of SBL FU_TS

10.4.10 Allowed States of Managed Object (SBL) OMU




MSA (2) Unlocked No change - Suspended

Table 45: Allowed States of Managed Object (SBL) OMU

(2) The OMU SBL can only have the state MSA when performing anAuto-Restart or Auto-Reset. Since no commands are handled by the OMUuntil it is completely operational, its MSA state is never seen by the operatorexcept from the BTS terminal.

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10.4.11 Allowed States of Managed Object (SBL) RA









Table 46: Allowed States of Managed Object (SBL) RA

10.4.12 Allowed States of SBL RTE


IT - - - -

FIT - - - -

FLT - - - -

SOS - - - -

OPR - - - -

MSD - - - -

MSA - - - -

NEQ - - - -

Table 47: Allowed States of SBL RTE

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10.5 Allowed Managed Object and SBL Actions for the G1 BTSMark 2 and G2 BTS

The Managed Object and SBL commands which are allowed for the ManagedObjects and SBLs of the G1 BTS and G2 BTS are indicated by a checkmark(X) in the following table.

ManagedObjectCommand Unlock Lock Restart Reset Shutdown

SBL CommandReadStatus Initialize Disable Restart Reset

ManagedObject/SBLType

BTS X - - X X -

CCF X X X - - X

CLLK X X X - - X

CU X X X - - X

EACB X - - - - -

FHU X X X - - X

FU X X X X X X

FU_TS X - - - - -

OMU X - - X X -

RA X X X - - X

RTE (1) X X X - - -

Table 48: Allowed Managed Object and SBL Commands for the G1 BTS and G2 BTS

(1) The OMC-R does not furnish the RTE-loop-test operations.

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10.6 G1 BTS Mark 2 RITsG1 BTS Mark 2 RITs are listed in the following table.

RIT Name RIT FunctionG1 BTS Mark2 RITs

O&MControlled

BPSU Booster Power Supply Unit X X

CBC2 Celwave Basic Combiner for Two Carriers X X

CBC4 Celwave Basic Combiner for Four Carriers X X

CDEC Channel Decoder X X

CEC2 Celwave Extension Combiner for Two Carriers X X

CEC4 Celwave Extension Combiner for Four Carriers X X

CECC Channel Encoder Encryption X X

CFSR Cooling Fan Subrack X X

CFSU Cooling Fan Subunit X X

CFT1 Cooling Fan Type 1 X X

CFT2 Cooling Fan Type 2 X X

CLDB Clock Distribution Board X X

CPDB Cabinet Power Distribution Board X -

CRDE Celwave Receiver Front-End with Antenna Diversity X X

CRFE Celwave Receiver Front-End without Antenna Diversity X X

DMAD Demodulator with Antenna Diversity X X

DMOD Demodulator without Antenna Diversity X X

DRFE Dual Rate Frame Unit Extension X X

DRFU Dual Rate Frame Unit X X

EACB External Alarm Collection Board X X

EAIB External Alarm Interconnection Board X -

ECF2 Forem Extension Combiner for Two High-Power Carriers X -

FBC2 Forem Basic Combiner for Two Carriers X X

FCAV Forem Supplementary Combiner for Two Carriers X X

FEC2 Forem Extension Combiner for Two Carriers X X

FQHU Frequency Hopping Unit X X

FUCO Frame Unit Controller X X

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RIT Name RIT FunctionG1 BTS Mark2 RITs

O&MControlled

FUIF Frame Unit Interface X X

MCEX Multicoupler Extension X -

MCLR Master Clock Repeater X X

MCLU Master Clock Unit X X

MFGE Master Frequency Generator X X

MFGP Master Frequency Generator PCM X X

OMUA Operations and Maintenance Unit Type A X X

RTDE Receiver Front-End with Antenna Diversity (Tower mounted) X X

RTEM Radio Test Equipment Mark 1/Mark 2 X X

RTMA Receiver Tower Mounted Amplifier X X

RTSE Receiver Front-End without Antenna Diversity (TowerMounted)

X X

RXAS Receiver (Mark 2) X X

RXDE Receiver Front-End with Antenna Diversity X X

RXFE Receiver Front-End without Antenna Diversity X X

SUPS Station Unit Power Supply X X

TAMF Forem Transmit Antenna Measuring Unit X X

TBCF Booster Cooling Fan X X

TBPS Transceiver Booster Power Supply X X

TCFB Top Cooling Fan Board X X

TCFU Top Cooling Fan Unit X X

TCPS Transceiver Power Supply X X

TXAH Transmitter Amplifier High Power X X

TXAL Transmitter Amplifier Low Power X X

TXBM Transmitter Booster Module X X

TXUA Transmitter Unit Type A X X

Table 49: G1 BTS Mark 2 RITs

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10.7 G1 BTS Mark 2 SBLs and RITs Reported to the OMC-RThe G1 BTS SBLs and RITs reported to the OMC-R are listed in the followingtable.

SBL G1 BTS Mark 2 RITs

BTS OMUA, SUPS

CCF CFSU, TBCF, TCFB, TCFU

CLLK CLDB, MCLR, MCLU, MFGE, MFGP

RA CBC2, CBC4, CEC2, CEC4,CRDE, CRFE, FBC2, FCAV,FEC2, RTDE, RTMA, RTSE, RXDE, RXFE, TAMF

CU BPSU, RXAS, TBPS, TCPS, TXAH, TXAL, TXBM, TXUA

EACB EACB

FHU FQHU

FU CDEC, CECC, DMAD, DMOD, DRFE, DRFU, FUCO,FUIF, TCPS

FU_TS None

OMU OMUA

RTE RTEM

Table 50: G1 BTS MARK 2 SBLs and RITs Reported to the OMC-R

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10.8 G2 BTS RITsG2 BTS RITs are listed in the following table.

RITName

RITFunction

GSM900 GSM 1800 GSM 1900

O&MControlled

ADPS AC/DC Power Supply X X X X

BBU2 Battery Backup Unit 12 Ah X X X -

BCU1 Battery Control Unit 1 X X X -

BHPS Battery and Heat Power Supply X X X -

BU60 Battery Unit 60 Ah X X X -

CFU1 Cooling Fan Unit 1 U X X X X

CFUA Cooling Fan Unit Additional X X X X

CFUT Cooling Fan Unit Top X X X X

COB1 Connection Box 1 (Power) X X X -

COB2 Connection Box 2 (Data) X X X -

CRBG Celwave Remotely Tunable CombinerBasic GSM

X - - X

CREG Celwave Remotely Tunable CombinerExtension GSM

X - - X

CUDP Carrier Unit Dummy Panel X X X -

DADE Demodulator and Channel Decoder withAntenna Diversity

X X X X

DCDB Device Control Distribution Board X X X -

DRFU Dual Rate Frame Unit X X X X

DUD2 Duplexer DCS for Two Transmitters - X - X

DUPD Wideband Combiner Two Carrier withIntegrated Duplexer

- X - X

DUPG Receiver Duplex GSM X - - X

DUPP Wideband Combiner Two Carrier withIntegrated Duplexer

- - X X

EADB External Alarm Distribution Board X X X -

FCPS Frame/Carrier Power Supply X X X X

FED2 Receiver Front-End D800 for Two Carriers - X - X

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RITName

RITFunction

GSM900 GSM 1800 GSM 1900

O&MControlled

FED8 Receiver Front-End DCS 1800 for EightCarriers

- X - X

FEG2 Receiver Front-End GSM for Two Carriers X - - X

FEG8 Receiver Front-End GSM for EightCarriers

X - - X

FEP8 Receiver Front-End DCS 1900 for EightCarriers

- - X X

FICE Frame Unit Interface and ChannelEncoder

X X X X

FRBG Forem Remotely Tunable Combiner BasicGSM

X - - X

FREG Forem Remotely Tunable CombinerExtension GSM

X - - X

FUCO Frame Unit Controller X X X X

FUDP Frame Unit Dummy Panel X X X -

HEAT Heating Unit X X X -

HEX1 Heat Exchanger 1 X X X -

HEXU Heat Exchanger Unit X X X -

LPQG Lightning Protector Quarter Wave GSM X X X -

LPSG Lightning Protector Spark Gap X X X -

MBPS Mini-BTS Power Supply X X X X

MCIB Mini-BTS Cabinet Indoor Connection Box X X X -

MDSW Mini-BTS Door Switch X X X -

PM06 Power Module 0.6 kW X X X -

PM08 Power Module 0.8 kW X X X -

PSI1 Power Supply Interface Type 1 X X X -

PSI2 Power Supply Interface Type 2 X X X -

RC4D Remotely Tunable Combiner for FourCarriers DCS

- X - X

RC8D Remotely Tunable Combiner for EightCarriers DCS

- X - X

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RITName

RITFunction

GSM900 GSM 1800 GSM 1900

O&MControlled

RMCD Receiver Multicoupler DCS - X - X

RMCG Receiver Multicoupler GSM X - - X

RTED Radio Test Equipment Unit for DCS - X - X

RTEG Radio Test Equipment Unit GSM X - - X

RXDD Receiver DCS 1800 with AntennaDiversity

- X - X

RXGD Receiver GSM with Antenna Diversity X - - X

RXPD Receiver DCS 1900 with AntennaDiversity

- - X X

SACE Station Unit Alarm Collection Entity X X X X

SCFE Station Unit Control Function Entity X X X X

STSE Station Unit Timing and Switching EntityMaster

X X X X

STSP Station Unit Timing and Switching EntityPCM Master

X X X X

STSR Station Unit Timing and Switching EntityRepeater

X X X X

TMAD Tower Mounted Amplifier DCS - X - X

TMAG Tower Mounted Amplifier GSM X - - X

TXDH Transmitter DCS1800 25 W - X - X

TXDM Transmitter DCS 1800 15 W - X - X

TXGH Transmitter GSM 50 W X - - X

TXGM Transmitter GSM 30 W X - - X

TXPH Transmitter DCS 1900 25 W - - X X

WB2D Wideband Combiner DCS for TwoCarriers

- X - X

WB2G Wideband Combiner GSM for TwoCarriers

X - - X

Table 51: G2 BTS RITs

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10.9 G2 BTS SBLs and RITs Reported to the OMC-RThe G2 BTS SBLs and RITs reported to the OMC-R are listed in the followingtable.

SBL RITs for GSM 900 RITs for GSM 1800 RITs for GSM 1900

BTS ADPS, MBPS, SCFE ADPS, MBPS, SCFE ADPS, MBPS, SCFE

CCF CFU1, CFUA, CFUT CFU1, CFUA, CFUT CFU1, CFUA, CFUT

CLLK STSE/STSP/STSR STSE/STSP/STSR STSE/STSP/STSR

RA CRBG, CREG, DUPG,FEG2, FEG8, FRBG,FREG, RMCG, TMAG,WB2G

DUD2, DUPD, FED2,FED8, RC4D, RC8D,RMCD, TMAD, WB2D

DUPP, FEP8

CU FCPS, MBPS, RXGD,TXGM, TXGH

FCPS, MBPS, RXDD,TXDM, TXDH

RXPD, TXPH

EACB SCFE/SACE SCFE/SACE SCFE/SACE

FHU STSE/STSR/STSP STSE/STSR/STSP STSE/STSR/STSP

FU DRFU

For FU3: DADE, FCPS,FICE, FUCO, MBPS

For FU2: FCPS, MBPS

DRFU


For FU2: FCPS, MBPS

DRFU


For FU2: FCPS, MBPS

FU_TS None None None

OMU SCFE SCFE SCFE

RTE RTEG RTED -

Table 52: G2 BTS SBLs and RITs Reported to the OMC-R

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10.10 BTS RBLs and Local Fault Indication via LEDsMost of the BTS RITs have LEDs mounted on their front panels. These conformto the following colors and status for maintenance purposes:

Green LEDThe RIT is powered when the green LED is ON unless otherwise stated.There can be more than one green LED.

Red LEDFlashing or continuously ON in the case of permanent failure.

Yellow LEDsThese LEDs indicate software checks. Consult the hardware description ofthe particular RIT to obtain more detailed information about the function ofthese LEDs.

The following tables list the associated RBL for each RIT. Where more thanone RBL exists, the disable sequence is shown.

The front panel LEDs for each RIT are indicated by a checkmark (X). A dash (-)indicates that no LED is present. In many cases there is more than one LED ofa particular color. The exact function of each LED is not within the scope of thisdocument. For more information, refer to t the G2 BTS Hardware Description .

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10.10.1 G1 BTS Mark 2 RITs with Corresponding RBL and LEDIndications

RIT Name RBL Green LED Red LED Yellow LED

BPSU CUi X - -

CBC2 RA X X -

CBC4 RA X X -

CDEC FUi X X -

CEC2 RA - - -

CEC4 RA - - -

CECC FUi X X -

CFSR CCF X X -

CFSU CCF - - -

CLDB CLLK X - -

CRDE RA - - -

CRFE RA - - -

DMAD FUi X X -

DMOD FUi X X -

DRFE FUi X X -

DRFU FUi X X X

EACB N/A - X -

FBC2 RA X X -

FCAV RA - - -

FEC2 RA X - -

FQHU RA X X X

FUCO FUi X X X

FUIF FUi X X -

MCLR CLLK X X -

MCLU CLLK X X -

MFGE CLLK - - -

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MFGP CLLK X X -

OMUA N/A X X X

RTDE RA Yellow for this RIT X X

RTEM RTE - - -

RTMA RA - - -

RTSE RA X X X

RXDE RA Yellow for this RIT X -

RXFE RA Yellow for this RIT X -

RXAS CUi - - -

SUPS N/A X X -

TAMF RA - - -

TBCF CCF X X -

TBPS RA - - -

TCFB CCF - - -

TCFU CCF X X -

TCPS CUi/FUi - - -

TXAL CUi - - -

TXAH CUi - - -

TXBM X X -

TXUA CUi X X -

Table 53: G1 BTS Mark 2 RITs with Corresponding RBL and LED Indications

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10.10.2 G2 BTS (GSM 900/1800/1900) RITs with Corresponding RBLsand LED Indications


ADPS N/A X - -

BCU1 N/A X X X

BHPS N/A X X -

CFU1 CCF X X -

CFUA CCF - - -

CFUT CCF - - -

DEDE FUi X X -

DRFU FUi X X X

FCPS FUi, CUi X - -

FICE FUi X X X

FUCO FUi X X X

MBPS FUi, CUi X - -

MSPS FUi, CUi X - -

PM06 N/A X X -

PM08 N/A X - -

PSI1 N/A - - -

PSI2 N/A - - -

SACE EACB X X X

SCFE EACB,OMU

X X X

STSE FHU,CLLK

X X -

STSP FHU,CLLK

X X -

STSR FHU,CLLK

X X -

Table 54: G2 BTS (GSM 900/1800/1900) RITs with Corresponding RBLs and LED Indications

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10.10.3 RITs Specific to G2 BTS GSM 900 with Corresponding RBLsand LED Indications


CRBG RA X X -

CREG RA - - -

DUPG RA - X -

FEG2 RA X X X

FEG8 RA X X X

FRBG RA X X -

FREG RA X - -

RMCG RA X X X

RTEG RTE - - -

RXGD CUi - - -

TMAG RA - - -

TXGH CUi - Red LED 7 segmentdisplay

-

TXGM CUi - Red LED 7 segmentdisplay

-

WB2G RA - X -

Table 55: RITs Specific to G2 BTS GSM 900 with Corresponding RBLs and LED Indications

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10.10.4 RITs Specific to G2 BTS GSM 1800/1900 with CorrespondingRBLs and LED Indications


DUD2 RA - X -

DUPD RA - X -

DUPP RA - X -

FED2 RA X X X

FED8 RA X X X

FEP8 RA X X X

RC4D RA X X -

RC8D RA X X X

RMCD RA X X X

RTED RTE - - -

RXDD CUi - - -

RXPD CUi - - -

TMAD RA - - -

TXDH CUi - - -

TXDM CUi - X -

TXPH CUi - - -

WB2D RA - X -

Table 56: RITs Specific to G2 BTS GSM 1800/1900 with Corresponding RBLs and LED Indications

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Bts Fuctional Description

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