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Part 1 System Description

Table of Contents i.........................................................................................

Chapter 1 An Introduction to BTS312 1-1..........................................................

1.1 System Overview 1-1..............................................................................1.2 System Characteristics 1-2.....................................................................

1.2.1 Integrated RF Component Technology 1-2....................................

1.2.2 Mature RF Technology 1-2.............................................................

1.2.3 Advanced E-Abis Technology 1-2..................................................

1.2.4 Powerful O&M Functions 1-3..........................................................

1.3 Application Merits 1-3..............................................................................

1.3.1 Wide Coverage 1-3.........................................................................

1.3.2 Expenditure Reduction 1-4.............................................................

1.3.3 Smooth Evolution 1-4.....................................................................

1.3.4 Multiple Transmission Modes 1-4...................................................

1.4 Structure Overview 1-4...........................................................................

1.4.1 Logical Structure 1-4.......................................................................

1.4.2 Software Structure 1-6....................................................................

1.4.3 Cabinet Structure 1-7......................................................................

1.5 Main Functions 1-8..................................................................................

1.5.1 Basic Software Relative Functions 1-8...........................................

1.5.2 Basic Hardware Relative Functions 1-9..........................................

1.6 Technical Indices 1-9..............................................................................

Chapter 2 Hardware Architecture 2-1.................................................................

2.1 Overview 2-1...........................................................................................

2.2 TRX/CDU Frame 2-3...............................................................................

2.2.1 CDU 2-3..........................................................................................

2.2.2 EDU 2-4..........................................................................................

2.2.3 ECDU 2-5.......................................................................................

2.2.4 SCU 2-6..........................................................................................

2.2.5 TRX 2-6..........................................................................................2.2.6 PBU 2-10..........................................................................................

2.3 Common Resource Frame 2-12................................................................

2.3.1 PSU 2-12..........................................................................................

2.3.2 PMU 2-12..........................................................................................

2.3.3 TMU 2-14..........................................................................................

2.3.4 TES 2-17...........................................................................................

2.3.5 ASU 2-18..........................................................................................

2.3.6 ABB 2-20..........................................................................................

2.3.7 ABA 2-21..........................................................................................2.4 Other Parts of the Cabinet 2-21................................................................

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2.4.1 TDU 2-21..........................................................................................

2.4.2 FMU 2-23..........................................................................................

2.4.3 Switch Box 2-24................................................................................

2.4.4 Fan Box 2-24....................................................................................

2.4.5 Air Box 2-25......................................................................................

2.5 Antenna and Feeder System 2-25............................................................

2.5.1 Antenna 2-25....................................................................................

2.5.2 Feeder 2-27......................................................................................

2.5.3 Lightning Arrester 2-27.....................................................................

2.5.4 Tower-top Amplifier (Optional) 2-27..................................................

2.6 Power Supply System 2-28.......................................................................

2.6.1 Overview 2-28...................................................................................

2.6.2 Overall Structure 2-30.......................................................................

2.6.3 Technical Specifications 2-32...........................................................

2.7 Environment Monitoring System 2-36.......................................................

2.7.1 Outlook of Environment Monitoring instrument 2-36........................

2.7.2 Function Provided by Environment Monitoring Instrument 2-37.......

2.7.3 Environment Monitoring Instrument Inputs 2-37...............................

2.7.4 Alarm Indicators 2-38........................................................................

2.7.5 Executing Devices 2-38....................................................................

2.7.6 Communication 2-39.........................................................................

2.8 Lightning Protection System 2-39.............................................................2.8.1 Lightning Protection for DC Power Supply 2-40...............................

2.8.2 Lightning Protection for AC Power Supply 2-42...............................

2.8.3 Lightning Protection for Trunk Cables 2-43......................................

Chapter 3 Software Architecture 3-1..................................................................

3.1 Overview 3-1...........................................................................................

3.2 Signaling Control Processing (SCP) Program 3-2..................................

3.3 Baseband Signal Processing Program 3-4.............................................

3.4 Operation and Maintenance Program 3-5...............................................

Chapter 4 External Interfaces 4-1.......................................................................4.1 Abis Interface 4-1....................................................................................

4.1.1 Introduction 4-1...............................................................................

4.1.2 Physical Layer 4-6..........................................................................

4.1.3 Data Link Layer 4-7........................................................................

4.1.4 Layer 3-Traffic Management 4-8....................................................

4.1.5 Layer 3-Operation and Maintenance 4-12........................................

4.2 Um Interface 4-14.....................................................................................

4.2.1 Introduction 4-14...............................................................................

4.2.2 Interface Protocol Model 4-15...........................................................

4.2.3 Physical Layer 4-15..........................................................................

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4.2.4 Data Link Layer 4-20........................................................................

4.2.5 Signaling Layer 4-23.........................................................................

Chapter 5 Functions and Performance 5-1........................................................

5.1 Networking Functions 5-1.......................................................................

5.1.1 E1 Networking 5-1..........................................................................

5.1.2 SDH Networking 5-3.......................................................................

5.1.3 Networking for Satellite Transmission 5-4......................................

5.2 Main RF Functions 5-6............................................................................

5.3 Baseband Processing 5-8.......................................................................

5.3.1 Channel Types Supported 5-8........................................................

5.3.2 Channel Combinations Supported 5-9............................................

5.4 Signaling Processing 5-9........................................................................

5.5 Operation and Maintenance 5-12..............................................................

5.5.1 Software Loading 5-12......................................................................

5.5.2 Abis Interface Management 5-13......................................................

5.5.3 Air Interface Management 5-14........................................................

5.5.4 Testing Management 5-16................................................................

5.5.5 Status Management 5-16.................................................................

5.5.6 Processing of Event Reports 5-17....................................................

5.5.7 Equipment Management 5-18..........................................................

5.5.8 Site Configuration 5-20.....................................................................

5.5.9 Tracing Operations 5-20...................................................................5.5.10 Miscellaneous Functions 5-21........................................................

5.6 System Indices 5-21..................................................................................

5.7 Radio Interface Indices 5-23.....................................................................

5.7.1 Receiver Part 5-23............................................................................

5.7.2 Transmitter Part 5-26........................................................................

Chapter 6 Configuration and Typical Application 6-1.........................................

6.1 Configuration 6-1.....................................................................................

6.1.1 Cell Configuration 6-1.....................................................................

6.1.2 Configuration of the Common Resource Frame 6-2.......................6.1.3 Configuration of the TRX/CDU Frame 6-2......................................

6.1.4 Configuration of the Antenna 6-4....................................................

6.2 Typical Configuration 6-4........................................................................

6.2.1 S (4/4/4) Configuration 6-4.............................................................

6.2.2 S (2/2/2) Configuration 6-6.............................................................

6.2.3 O (6) Configuration 6-8...................................................................

6.2.4 O (4) Configuration 6-10...................................................................

Appendix A Abbreviations A-1............................................................................

Part 2 Maintenance Console Description

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Chapter 1 Overview 1-1......................................................................................

1.1 Introduction to BTS Terminal Maintenance 1-1.......................................

1.2 Introduction to BTS Terminal Maintenance Operations 1-1....................

1.2.1 User Login 1-1................................................................................

1.2.2 Interface Operation 1-2...................................................................

Chapter 2 Site Maintenance 2-1.........................................................................

2.1 Overview 2-1...........................................................................................

2.2 Site Administrationship 2-1.....................................................................

2.3 OpStart Site 2-3......................................................................................

2.4 View Resource 2-4..................................................................................

2.5 Forced Load SW 2-4...............................................................................

2.6 SW Activate 2-6......................................................................................

2.7 Site Hierarchical Reset 2-7.....................................................................

2.8 Site Test 2-9............................................................................................

2.9 Site Environment Monitoring 2-9.............................................................

Chapter 3 Cell Maintenance 3-1.........................................................................

3.1 Overview 3-1...........................................................................................

3.2 Cell Attributes Management 3-2..............................................................

3.3 Cell Extended Attribute Management 3-4...............................................

3.4 OpStart Cell 3-6......................................................................................

3.5 Change Cell Administrative State 3-6.....................................................3.6 Cell Performance Test 3-7......................................................................

Chapter 4 BT Maintenance 4-1..........................................................................

4.1 Overview 4-1...........................................................................................

4.2 OpStart BT 4-2........................................................................................

4.3 Change BT Administrative State 4-2.......................................................

4.4 BT Reinitialization 4-3.............................................................................

4.5 BT Test 4-4.............................................................................................

Chapter 5 Channel Maintenance 5-1..................................................................

5.1 Overview 5-1...........................................................................................5.2 Channel Attributes Management 5-2......................................................

5.3 OpStart Channel 5-3...............................................................................

5.4 Change Channel Administrative State 5-3..............................................

5.5 Loop Test 5-4..........................................................................................

Chapter 6 RC Maintenance 6-1..........................................................................

6.1 Overview 6-1...........................................................................................

6.2 RC Attributes Management 6-2...............................................................

6.3 RC Extended Attributes Management 6-3..............................................

6.4 OpStart RC 6-4.......................................................................................

6.5 Change RC Administrative State 6-4......................................................

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6.6 RC Reinitialization 6-5.............................................................................

Chapter 7 Board Maintenance 7-1.....................................................................

7.1 Overview 7-1...........................................................................................

7.1.1 Board Maintenance 7-1..................................................................

7.1.2 Board Maintenance Operations 7-2................................................

7.2 Board Reset 7-4......................................................................................

7.3 OpStart Board 7-4...................................................................................

7.4 Board Self-test 7-5..................................................................................

7.5 Change Board Administrative State 7-5..................................................

7.6 Board Information 7-6.............................................................................

7.7 Loop Test 7-7..........................................................................................

7.8 Board Alarm 7-8......................................................................................

7.9 Clock Operation 7-9................................................................................

7.10 Set Antenna and Feeder Parameters 7-10.............................................

7.11 CDU Operation 7-11...............................................................................

Part 3 BTS Maintenance


Chapter 1 Routine Maintenance Instructions 1-1...............................................

1.1 Routine Maintenance Overview 1-1........................................................

1.1.1 Purpose of Routine Maintenance 1-1.............................................

1.1.2 Routine Maintenance Classification 1-1.........................................

1.1.3 BTS Routine Maintenance Record & Instructions 1-2....................

1.2 Weekly Maintenance Instructions 1-8.....................................................

1.3 Monthly Maintenance Instructions 1-9....................................................

1.4 Quarterly Maintenance Instructions 1-10..................................................

1.5 Yearly Maintenance Instructions 1-11.......................................................

1.6 Return Loss, VSWR and Reflection Coefficient 1-12................................

Chapter 2 Fault Analysis and Location 2-1.........................................................

2.1 Communication Fault 2-1........................................................................

2.1.1 Introduction to MSs Search for the Network 2-1............................2.1.2 Call Failure 2-2...............................................................................

2.1.3 No Voice Heard after the Call is Connected 2-5.............................

2.1.4 Unidirectional Talk 2-6....................................................................

2.1.5 Poor Voice Quality 2-7....................................................................

2.1.6 Conversation Interruption 2-8.........................................................

2.1.7 Cross Talk 2-8................................................................................

2.1.8 Mobile Station Frequently Disconnected from the Network 2-9......

2.1.9 Immediate Assignment Rejection 2-10.............................................

2.2 Network Fault 2-10....................................................................................2.2.1 Mobile Station Fails to Find a Network 2-10.....................................

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2.2.2 Mobile Station Fails to Access the Network 2-12.............................

2.2.3 MS Frequent Location Updating 2-14...............................................

2.3 Loading Fault 2-15....................................................................................

2.3.1 Software Loading Failure 2-15..........................................................

2.3.2 Base Station Initialization Failure 2-17.............................................

2.4 Signaling Fault 2-19..................................................................................

2.4.1 OML Link Blocked 2-19....................................................................

2.4.2 RSL Link Blocked 2-19.....................................................................

2.5 Antenna and Feeder System Fault 2-20...................................................

2.5.1 Fault Description 2-20.......................................................................

2.5.2 Introduction to the Antenna and Feeder System 2-21......................

2.5.3 Fault Analysis and Location 2-21......................................................

2.5.4 Troubleshooting Procedure 2-21......................................................

2.6 Optical Channel Fault 2-22.......................................................................

2.6.1 Fault Description 2-22.......................................................................

2.6.2 Fault Analysis and Location 2-22......................................................

2.6.3 Troubleshooting Procedure 2-22......................................................

2.7 Board Fault 2-23.......................................................................................

2.7.1 TMU 2-23..........................................................................................

2.7.2 CDU 2-25..........................................................................................

2.7.3 EDU 2-29..........................................................................................

2.7.4 SCU 2-32..........................................................................................2.7.5 TRX 2-34..........................................................................................

2.7.6 PBU 2-36..........................................................................................

2.7.7 PMU 2-38..........................................................................................

2.7.8 PSU 2-42..........................................................................................

2.7.9 TEU 2-43..........................................................................................

2.7.10 TES 2-45.........................................................................................

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HUAWEI

1. System Description

2. Maintenance Console Description

3. BTS Maintenance

M900/M1800 Base Transceiver Station (BTS312)

User Manual

V300R002

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M900/M1800 Base Transceiver Station (BTS312)

User Manual

Manual Version T2-030129-20040310-C-4.03

Product Version V300R002

BOM 31013229

Huawei Technologies Co., Ltd. provides customers with comprehensive technical support

and service. Please feel free to contact our local office or company headquarters.

Huawei Technologies Co., Ltd.

Address: Administration Building, Huawei Technologies Co., Ltd.,

Bantian, Longgang District, Shenzhen, P. R. China

Postal Code: 518129

Website: http://www.huawei.com

Email: [email protected]

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Copyright 2004 Huawei Technologies Co., Ltd.

All Rights Reserved

No part of this manual may be reproduced or transmitted in any form or by any

means without prior written consent of Huawei Technologies Co., Ltd.

Trademarks

, HUAWEI, C&C08, EAST8000, HONET, , ViewPoint, INtess, ETS, DMC,

TELLIN, InfoLink, Netkey, Quidway, SYNLOCK, Radium, M900/M1800,

TELESIGHT, Quidview, Musa, Airbridge, Tellwin, Inmedia, VRP, DOPRA, iTELLIN,

HUAWEI OptiX, C&C08iNET, NETENGINE, OptiX, iSite, U-SYS, iMUSE, OpenEye,

Lansway, SmartAX, infoX, TopEng are trademarks of Huawei Technologies Co.,

Ltd.

All other trademarks mentioned in this manual are the property of their respective

holders.

Notice

The information in this manual is subject to change without notice. Every effort has

been made in the preparation of this manual to ensure accuracy of the contents, but

all statements, information, and recommendations in this manual do not constitute

the warranty of any kind, express or implied.

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About This Manual

Release Notes

The product version that corresponds to the manual is M900/M1800 Base Transceiver

Station (BTS312) V300R002.

Related Manuals

The following manuals provide more information about the M900/M1800 Base

Transceiver Station (BTS312).

Manual Content

M900/M1800 Base TransceiverStation (BTS312) User Manual

It provides an overall introduction to the BTS312, includingthe software structure, hardware structure, applications,technical specifications and maintenance method.

M900/M1800 Base Transceiver Station(BTS312) Installation Manual

It provides information for the system installation, includingthe hardware installation and software installation.

Organization of the Manual

M900/M1800 Base Transceiver Station (BTS312) User Manual describes such

contents of the BTS312as the product features, architecture, and working principle of

each functional part. It includes 3 volumes and their contents are listed as follows:

System Description gives a general description of the BTS312, including the key

features, technical indices, functions, and operation and maintenance structure, and

users can get the basic information of BTS312.

Maintenance Console Description is used to guide users how to operate the local

maintenance console. It describes every operation by means of interface, and helps

users to get familiar with the routine operation of the BTS312, and learn about its

running status.

BTS Maintenance introduced the routine maintenance instructions, faulty analysis and

location of BTS312.

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HUAWEI

M900/M1800 Base Transceiver Station (BTS312)User Manual

Part 1 System Description

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User ManualM900/M1800 Base Transceiver Station (BTS312)

System DescriptionTable of Contents

i

Table of Contents

Chapter 1 An Introduction to BTS312 ......................................................................................... 1-11.1 System Overview............................................................................................................... 1-11.2 System Characteristics...................................................................................................... 1-2

1.2.1 Integrated RF Component Technology................................................................... 1-21.2.2 Mature RF Technology............................................................................................ 1-21.2.3 Advanced E-Abis Technology................................................................................. 1-21.2.4 Powerful O&M Functions ........................................................................................ 1-3

1.3 Application Merits............................................................................................................... 1-31.3.1 Wide Coverage........................................................................................................ 1-31.3.2 Expenditure Reduction............................................................................................ 1-41.3.3 Smooth Evolution.................................................................................................... 1-41.3.4 Multiple Transmission Modes.................................................................................. 1-4

1.4 Structure Overview ............................................................................................................ 1-41.4.1 Logical Structure ..................................................................................................... 1-41.4.2 Software Structure .................................................................................................. 1-61.4.3 Cabinet Structure .................................................................................................... 1-7

1.5 Main Functions................................................................................................................... 1-81.5.1 Basic Software Relative Functions.......................................................................... 1-81.5.2 Basic Hardware Relative Functions ........................................................................ 1-9

1.6 Technical Indices ............................................................................................................... 1-9Chapter 2 Hardware Architecture ................................................................................................2-1

2.1 Overview............................................................................................................................ 2-12.2 TRX/CDU Frame................................................................................................................ 2-3

2.2.1 CDU......................................................................................................................... 2-32.2.2 EDU......................................................................................................................... 2-42.2.3 ECDU ...................................................................................................................... 2-52.2.4 SCU......................................................................................................................... 2-62.2.5 TRX ......................................................................................................................... 2-62.2.6 PBU....................................................................................................................... 2-10

2.3 Common Resource Frame .............................................................................................. 2-122.3.1 PSU....................................................................................................................... 2-122.3.2 PMU ......................................................................................................................2-122.3.3 TMU....................................................................................................................... 2-142.3.4 TES ....................................................................................................................... 2-172.3.5 ASU....................................................................................................................... 2-182.3.6 ABB ....................................................................................................................... 2-202.3.7 ABA ....................................................................................................................... 2-21

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ii

2.4 Other Parts of the Cabinet ............................................................................................... 2-212.4.1 TDU....................................................................................................................... 2-212.4.2 FMU....................................................................................................................... 2-232.4.3 Switch Box............................................................................................................. 2-24

2.4.4 Fan Box................................................................................................................. 2-242.4.5 Air Box................................................................................................................... 2-25

2.5 Antenna and Feeder System........................................................................................... 2-252.5.1 Antenna................................................................................................................. 2-252.5.2 Feeder................................................................................................................... 2-272.5.3 Lightning Arrester.................................................................................................. 2-272.5.4 Tower-top Amplifier (Optional) .............................................................................. 2-27

2.6 Power Supply System...................................................................................................... 2-282.6.1 Overview ............................................................................................................... 2-282.6.2 Overall Structure ................................................................................................... 2-302.6.3 Technical Specifications........................................................................................ 2-32

2.7 Environment Monitoring System...................................................................................... 2-362.7.1 Outlook of Environment Monitoring instrument..................................................... 2-362.7.2 Function Provided by Environment Monitoring Instrument ................................... 2-372.7.3 Environment Monitoring Instrument Inputs ........................................................... 2-372.7.4 Alarm Indicators .................................................................................................... 2-382.7.5 Executing Devices................................................................................................. 2-382.7.6 Communication ..................................................................................................... 2-39

2.8 Lightning Protection System............................................................................................ 2-392.8.1 Lightning Protection for DC Power Supply............................................................ 2-402.8.2 Lightning Protection for AC Power Supply............................................................ 2-422.8.3 Lightning Protection for Trunk Cables................................................................... 2-43

Chapter 3 Software Architecture ................................................................................................. 3-13.1 Overview............................................................................................................................ 3-13.2 Signaling Control Processing (SCP) Program................................................................... 3-23.3 Baseband Signal Processing Program.............................................................................. 3-43.4 Operation and Maintenance Program ............................................................................... 3-5

Chapter 4 External Interfaces....................................................................................................... 4-1

4.1 Abis Interface..................................................................................................................... 4-14.1.1 Introduction.............................................................................................................. 4-14.1.2 Physical Layer......................................................................................................... 4-64.1.3 Data Link Layer ....................................................................................................... 4-74.1.4 Layer 3 - Traffic Management................................................................................. 4-84.1.5 Layer 3 - Operation and Maintenance .................................................................. 4-12

4.2 Um Interface .................................................................................................................... 4-144.2.1 Introduction............................................................................................................ 4-144.2.2 Interface Protocol Model ....................................................................................... 4-154.2.3 Physical Layer....................................................................................................... 4-15

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iii

4.2.4 Data Link Layer ..................................................................................................... 4-204.2.5 Signaling Layer...................................................................................................... 4-23

Chapter 5 Functions and Performance....................................................................................... 5-15.1 Networking Functions ........................................................................................................ 5-1

5.1.1 E1 Networking......................................................................................................... 5-15.1.2 SDH Networking...................................................................................................... 5-35.1.3 Networking for Satellite Transmission..................................................................... 5-4

5.2 Main RF Functions............................................................................................................. 5-65.3 Baseband Processing........................................................................................................ 5-8

5.3.1 Channel Types Supported ...................................................................................... 5-85.3.2 Channel Combinations Supported .......................................................................... 5-9

5.4 Signaling Processing ......................................................................................................... 5-95.5 Operation and Maintenance ............................................................................................ 5-12

5.5.1 Software Loading .................................................................................................. 5-125.5.2 Abis Interface Management .................................................................................. 5-135.5.3 Air Interface Management..................................................................................... 5-145.5.4 Testing Management ............................................................................................ 5-165.5.5 Status Management.............................................................................................. 5-165.5.6 Processing of Event Reports................................................................................. 5-175.5.7 Equipment Management ....................................................................................... 5-185.5.8 Site Configuration.................................................................................................. 5-205.5.9 Tracing Operations................................................................................................5-205.5.10 Miscellaneous Functions..................................................................................... 5-21

5.6 System Indices................................................................................................................. 5-215.7 Radio Interface Indices.................................................................................................... 5-23

5.7.1 Receiver Part......................................................................................................... 5-235.7.2 Transmitter Part..................................................................................................... 5-26

Chapter 6 Configuration and Typical Application...................................................................... 6-16.1 Configuration...................................................................................................................... 6-1

6.1.1 Cell Configuration.................................................................................................... 6-16.1.2 Configuration of the Common Resource Frame ..................................................... 6-26.1.3 Configuration of the TRX/CDU Frame .................................................................... 6-2

6.1.4 Configuration of the Antenna .................................................................................. 6-4

6.2 Typical Configuration......................................................................................................... 6-46.2.1 S (4/4/4) Configuration............................................................................................ 6-46.2.2 S (2/2/2) Configuration............................................................................................ 6-66.2.3 O (6) Configuration.................................................................................................. 6-86.2.4 O (4) Configuration................................................................................................ 6-10

Appendix A Abbreviations ...........................................................................................................A-1

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System DescriptionChapter 1 An Introduction to BTS312

1-1

Chapter 1 An Introduction to BTS3121.1 System Overview

In a GSM network, a Base Transceiver Station (BTS) belongs to the radio part of the

base station subsystem, i.e. transmitting functions are performed by BTS. Figure 1-1

shows that a BTS is a set of transceiver equipment that serves a certain cell and is

controlled by the BSC (Base Station Controller).

MSC: Mobile Switching Center BSC: Base Station Controller SMC: Short Message Center

HLR: Home Location Register BTS: Base Transceiver Station VM: Voice Mailbox

AUC: AUthentication Center MS: Mobile Station OMC: Operation/Maintenance Center

VLR: Visitor Location Register EIR: Equipment Identify Register

Other MSC/VLR

MAP

M900 BTS

M900 BTS SMC&VMOMC

M900/M1800 BSC

TUP , ISUP

MAP

A interface

MSHLR/AUC/EIR

M900/M1800 MSC/VLR

M1800 BTSM900 BTS

PSTN

ISDNPSPDN

Um interface

MS

LAN/WAN

Figure 1-1Position of the BTSs in the GSM system

A BTS connects with the BSC via the Abis interface. The air interface (Um interface),

is used to realize the radio transmission between the BTS and the MS as well as the

associated control functions.

The BTS processes messages on layer 1, layer 2, and non-transparent transmission

layer 3 on radio links and performs the related control functions, including:

z Interfacing with the BSC

z Radio channel management

z Operation and maintenance functions

z Signaling protocol functions

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1-2

1.2 System Characteristics

The M900/M1800 BTS312 is designed as a typical all-in-one BTS by taking full

consideration of the requirements of capacity, configuration, installation, power supply,

transmission, and services. Its characteristics are as follows.

1.2.1 Integrated RF Component Technology

z Expansion based on the inheritance of the investment: BTS expansion can make

the utmost of all the antenna and feeder parts.

z Modular structure with good performance: RF combiner, divider and low noise

amplifier are integrated in CDU (Combining and Distribution Unit). All parts for

TRX processing including baseband processing, RF processing, poweramplification and power supply are all integrated in one TRX (Transceiver unit).

Modular structure can reduce internal cable connections, improve system

reliability and facilitate installation and maintenance.

z Intelligent CDU: Fine monitor and control function, excellent O&M, level 2

standing wave ratio alarm, low noise amplifier alarm, TTA (Tower Top Amplifier)

alarm, TTA power supply. Auto protection against emergency: Close

transmission power when transmit path antenna feeder is abnormal; power off to

bypass LNA (Low Noise Amplifier) when TTA is abnormal so as to ensure

normal system operation. Receive gain can be adjusted via remote control to

ensure the sensitivity of the receive system.

1.2.2 Mature RF Technology

z RF hopping and baseband frequency hopping are provided to improve system

anti-interference capability. It has good performance in practical application.

z Advanced digital RF technology is adopted to raise batch consistency,

manufacture scalability and stability of the RF system.

1.2.3 Advanced E-Abis Technology

The E-Abis (Enhanced Abis) supports various transmission modes and complex

topologies, e.g. SDH, E1, microwave, satellite, etc.

The E-Abis includes the following techniques:

z APL (Advanced Phase Locking) technique solves the problem of clock jittery, by

using high-precision clock and characteristic software phase lock technique. The

problems such as SDH clock phase jittery, signal out of lock during transmission

via satellite are solved.

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1-4

1.3.2 Expenditure Reduction

z It supports multiplexing of 15:1, hence greatly reducing transmission

expenditure.

z Transmission equipment such as SDH is integrated, providing a solution for

future upgrade and wideband radio access and reducing transmission equipment

investment.

z High reliability: Centralized power supply while providing power to various

modules in a distributed way. BTS312 can provide DC +24V, DC -48V and AC

220V to satisfy different power supply requirement.

1.3.3 Smooth Evolution

z Mixed dual band plug-in of 900MHz and 1800MHz modules of 6 cells.

z GPRS (General Packet Radio Service), which helps to realize smooth evolution

from 2G to 2.5G.

1.3.4 Multiple Transmission Modes

z Multiple built-in transmission modes: 75 /E1, 120/E1 and SDH. The BTS has

powerful transmission adaptability.

1.4 Structure Overview

1.4.1 Logical Structure

In the GSM system, the BTS functions as a radio relay, connected with the MS via the

Um interface on one side and to the BSC via the Abis interface on the other side.

The logical structure of the BTS is shown in Figure 1-2.

TRX

TRX

TRX

CDU

CDU

CDU

FHBUS

TTA TTA

TTA TTA

TTA TTA

PMUPSU

FMU

TDU

TMU

TEU TES

Abis

E1

Fiber(Optinal)

Common Unit Signaling Processor Unit Antenna Feeder Unit

External Alarm

Um

CBUS/TBUS/DBUS

BSC

ABB&ABA

Figure 1-2BTS312 logical structure

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1-5

As shown in Figure 1-2, the hardware of BTS312 includes the following three

functional parts: common unit, carrier unit and antenna unit.

I. Common Unit

The common unit consists of the Timing/transmission and Management Unit (TMU),

the Timing Distribution Unit (TDU), the Transmission Extension Unit (TEU), the

Transmission Extension power Supply unit (TES), the Fan Monitor Unit (FMU), the

Power Supply Unit (PSU), the Power Monitoring Unit (PMU), the switch box, the fan

box and the air box.

z TMU is the basic transmission and control function entity in a BTS

z TDU is installed on the top of the cabinet.

z TEU is an optional unit used for SDH transmission.

z TES is the power supply unit of TEU.z FMU within the fan box controls the normal operation of fans and reports alarms

in case of fan failure.

z PSU is the power supply unit for the whole system.

z PMU is the power monitoring unit.

z ABB is the Abis bypass board for the BTS312 in the chain networking.

z ABA is the Abis bypass assistant board.

z Switch box: distributed power supply is adopted to improve the reliability of

power supply.

z Fan box: FMU is installed within the fan box.

z Air box is the inlet for the cool air. It is part of the cooling system to guarantee

the normal operation of BTS.

II. Carrier unit

The carrier unit comprises Transceiver (TRX) unit, Power Booster Unit (PBU),

Combiner and Divider Unit (CDU), Enhanced Duplexer Unit (EDU) and Simple

Combiner Unit (SCU).

z TRX is a software and hardware entity that performs all processing functions of

one carrier.

z PBU is the output power booster of TRX. It also provides the function of alarm

collection.

z CDU supports broadband hybrid combining. At the transmitting end, signals of 2

channels are combined into 1 (2-into-1), while at the receiving end signals from 2

channels are divided into 4 (or 8 in case of only one channel) channels.

z EDU is a low-loss duplex divider unit which can achieve the transmitting and

diversity receiving of signals for two TRXs.

z SCU fulfills 4-into-1 combining. It is used to save CDUs.

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1-6

III. Antenna unit

Antenna unit implements the receiving and transmitting of RF signals. It includes the

antenna, feeder, low-loss transmission cable and lightning arrester.

1.4.2 Software Structure

BTS software not only performs the protocol functions specified in the signaling model

shown in Figure 1-3, but also implements BTS operation, maintenance and testing

functions.

Based on different hardware entities, BTS software consists of:

z Radio interface signal processing unit, i.e., the Um interface media access layer

running in the digital signal processing unit of the TRX module,z Signaling processing unit, including radio resources management (RR), Abis

interface link layer protocol (LAPD), Abis interface media access control layer,

Um interface link layer protocol (LAPDm), etc. which run in the signaling

processing unit of TRX module,

z Operation and maintenance unit, including BTS fault management, performance

management, configuration management, security management, data

management, Abis interface transmission control and local man-machine

interface, which run in the TMU unit.

z BTS software also includes the programs handling the communication among

various units in BTS.

MM

RR

LAPDm

Sign.

Layer 1

L3

L2

L1

LAPDm

Sign.

Layer 1

Sign.

LAPD

Layer 1

MS

Um

LAPD

Sign.

Layer 1

SCCP

MTP

BTSM

RR BSSAP

Abis

BTS BSC

RR

CM

BTSM

CM: Connection Management LAPD: Link Access Protocol on D channelMM: Mobility Management LAPDm: Link Access Protocol on Dm channelRR: Radio Resource Management SCCP: Signaling Connection Control PartBTSM: BTS Management MTP: Message Transfer PartBSSAP: Base Station Subsystem Application Part

Figure 1-3BTS signaling structure

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1-7

1.4.3 Cabinet Structure

I. Dimensions

The cabinet of the BTS312 is designed in accordance with the IEC297 standard, with

the following dimensions:

HeightWidthDepth=1880mm650mm500mm.

The cabinet is shown in Figure 1-4.

(1) TRX/CDUframe

(2) Rack (3) Common resource frame (4) Switch box (5) Small fan box

(6) Air box (7) Large fan box (8) Front door (9) Back plate

Figure 1-4General view of the cabinet

II. Cabinet features

z Standard cabinet.

z Strong and simple structure.

z

Aluminum alloys are used to reduce the cabinet's weight.

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1-8

z Good shielding effect and conductivity.

z Wind tunnels ensure good ventilation and heat dissipation.

z Simple and convenient installation and maintenance.

1.5 Main Functions

Basic functions provided by BTS312 software and hardware are listed below.

1.5.1 Basic Software Relative Functions

The BTS312 has the following main functions:

z Support both 900MHz and 1800MHz frequency systems.

z Support EGSM/RGSM extended frequency band services.

z All data services prescribed in Phase II+.

z Support GPRS.

z Support Phase I/Phase II /Phase II+ compatible LAPDm protocol.

z Support Phase I/Phase II/Phase II+ compatible system message issuing and

resources instruction.

z Support CS-1/CS-2/CS-3/CS-4 radio channel coding scheme.

z Support FR (Full Rate) / EFR (Enhanced Full Rate) / HR (Half Rate) and all

kinds of speech coding scheme.

z Support broadcast short message and point-to-point short message.

z Support paging queue.z Support A5/1, A5/2 encryption/decryption.

z Support basic data dynamic configuration.

z Support basic data dynamic configuration.

z Support measurement report preprocessing.

z Support Abis,10:1, 12:1 and 15:1signaling multiplexing.

z Support BCCH carrier cooperation.

z Support immediate assignment combination and paging combination, boosting

the radio channel efficiency.

z Support discontinuous transmission (DTX) enhancing the anti-interference ability

and reducing the power consumption. Support DRX.

z Support omni cell and directional cell.

z Support chain/tree/start/loop networking.

z Support locked, fast pull-in, holdover and free run clock modes.

z Support synchronous, asynchronous and quasi-synchronous handover.

z Support Um interface tracing and internal interface tracing.

z Support remote and local loading of software.

z Support dynamic and static power control.

z Support satellite transmission and Abis 16k signaling transmission.

z Support extended cell.

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1-10

Weight bearing requirement: 400kg/m2

(with 10% tolerance)

z Power consumption

Maximum power consumption of a single cabinet: 2400W

z Receiving sensitivity

-110dBm (GSM900), -109dBm (GSM1800)

z Transmitting power

TRX output power: 40W (46dBm) or 60W (47.8dBm)

TRX+PBU output power: 80W (49dBm)

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System DescriptionChapter 2 Hardware Architecture

2-1

Chapter 2 Hardware Architecture

2.1 Overview

A BTS312 cabinet mainly comprises a common resource frame and a TRX/CDU

frame, which can be flexibly configured according to the user demands. There are

also some other elements like TDU, switch box, fan box, air box, etc.

The hardware architecture of the BTS312 cabinet is shown in Figure 2-1.

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2-2

TX

RX

TRX

TX

RX

TRX

TX

RX

TRX

TX

RX

TRXCDU

TX

RX

TRX

TX

RX

TRX

TX

RX

TRX

TX

RX

TRXCDUCDU

TX

RX

TRX

TX

RX

TRX

TX

RX

TRX

TX

RX

TRXCDUCDU

AIR BOX

FAN BOXFAN BOX

P

M

P

S

U

P

S

U

P

S

U

P

S

U

P

S

U

P

S

U U

T

M

U

T

M

U

T

U

E

T

U

E

T

E

S

AIR BOX

SWITCH BOX

FAN BOX

TDU

CDU

CDU: Combiner and Divider Unit TRX: TransceiverPMU: Power supply Management Unit TMU: Timing/Transmission Management UnitPSU: Power Supply Unit TES: Transmission Extension power SupplyTEU: Transmission Extension Unit TDU: Timing Distribution Unit

Figure 2-1Hardware architecture of the BTS312 cabinet

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2-5

EDU

Test coupler Amp. feeder

Divider

Duplexer

LNA

Alarm and control unit

Tx signal input

Rx signal output

Divider

Rx signal output

LNA

Amp. feederTx signal input Duplexer Test coupler

Figure 2-3Functional blocks of the EDU

Besides the combining and dividing functions, the EDU also provides the following

alarm detection functions:

z VSWR (Voltage Standing Wave Ratio) monitoring: Monitoring the status of the

antenna system. When the VSWR exceeds the threshold 2.5:1, the EDU reports

alarm.

z Low noise amplifier fault alarm: The status of the LNA can be determined based

on the power supply current. When the current exceeds a certain level, alarm

signals and indications are generated.

z

Tower-top amplifier alarm: When there is tower-top amplifier in service, EDUdetermines the operation status of the amplifier according to the working current

of amplifier. If the current exceeds preset value or there is no current, alarm

signal will be generated.

z Control functions: Remotely control the low noise amplifier attenuation (dynamic

control 15 levels, in steps of 1dB) both in the main receiving path and diversity

receiving path, supply/cut feeder depends on whether tower-top amplifier is

equipped, cut the feeder to the amplifier in case of alarm.

2.2.3 ECDU

The functions and external interfaces (including dimensions) of ECDU are the same

as that of CDU. It implements combination of transmitted signals, dividing of received

signals, and duplex functions. The difference is that the maximum power input of

ECDU reaches 100W.

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2-6

2.2.4 SCU

I. General

SCU combines the signals from 4 TRXs into 1 channel for transmission. It employs

the electric bridge with 3dB power loss to achieve the broadband combing. Used

together with CDU, it can achieve the combination of signals from multiple TRXs. The

introduction of SCU is to reduce the number of CDUs, hence saving costs.

II. Structure and function

The functional blocks of the SCU are shown in Figure 2-4.

SCU

1

2

3

4

CombinerTx signal input

Combiner

Tx signal outputCombiner

Figure 2-4Functional blocks of the SCU

2.2.5 TRX

I. General

TRX is the key part of the BTS which receives various types of management and

configuration information issued by the TMU and reports its status and alarm

information to the TMU.

The TRX separates the received information from the mobile stations through

demodulation and balancing into signaling and speech information, and transmits

them upward (i.e. to BSC and MSC). The downlink signaling and speech information

is sent to the CDU and the antenna after being processed by the TRX.

With a modular structure, the TRX module contains both the baseband processing

unit, and the radio frequency unit.

II. Structure and functions

The structure of the TRX unit is shown in Figure 2-5. It includes the baseband signal

processing unit (TBU) and the radio frequency signal processing unit (RPU).

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2-7

SCP DSP CUITDP PAU

RCU

TBU RPU

DBUS FH _BUS

CBUS

TIMING_BUS

Clock processing part

Send

Main receiverDiversity receiver

SCP: Signaling Processing Unit DSP: Digital Signal Processing Unit CUI: Carrier Unit InterfacePAU: Power Amplifier Unit RCU: Receiving Unit TDP: Transmitter Driver and PLL unitRPU: RF signal Processing Unit TBPU: TRX Baseband signal Processing UnitCBUS: Control Bus FH_BUS: Frequency Hopping Bus DBUS: Data Bus

Figure 2-5Structure of the TRX unit

1) Baseband signal processing unit (TBU)

The TBU consists mainly of the Signaling Processing Unit (SCP), the Digital Signal

Processing unit (DSP), and the Carrier Unit Interface (CUI). As the GSM system is a

time division multiplexing system, the operation of the TRX relies on various clocks.

So the TRX contains some clock processing logical units.

z Signaling processing unit (SCP)

The SCP processes signaling protocols on different BTS interfaces, including the

layer 2 protocol LAPDm with the mobile station (MS), the layer 2 protocol LAPD with

the BSC interface, and the layer 2 protocol (DCL) with the operation & maintenance

module (OMU), as well as layer 3 non-transparent messages.

The SCP also handles DSP program loading and alarm processing of the whole TRX

module.

z Digital signal processing unit (DSP)

The DSP performs such functions as signal encoding/decoding, signal demodulation,

interleaving and de-interleaving, and speech/data communication with the TRAU.

It sends the signaling received from the MS to the SCP, receives signaling sent from

the SCP, and performs corresponding encoding/decoding according to related

protocols. It sends the downlink data via the CUI to the carrier unit RPU.

z Carrier unit interface (CUI)

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2-8

The CUI is the interface between the DSP and the RPU. It supports baseband

hopping, and according to system configuration can work in either hopping or

non-hopping mode (when the system works in the RF hopping mode, the hopping

interface works in non-hopping mode and the hopping functions are completed by thecarrier unit).

The CUI samples and filters the uplink intermediate frequency signals sent from the

RPU, and sends them to the DSP for demodulation and combination.

z Clock processing part

The TRX extracts clocks sent from the TMU over the clock buses. To ensure the

reliability, the clock buses work in active/standby mode. These clocks include the

frame clock, the octet bit clock, and the frame number.

The clock processing part in the TRX first chooses either the active clock or thestandby clock, then makes frequency division calculation and generates the timeslot

number and bit clocks required by the local TRX.

2) Radio frequency signal processing unit (RPU)

The RPU consists of 3 parts: Receiving Unit (RCU), Transmitter Driver and PLL unit

(TDP), and Power Amplification Unit (PAU).

z Receiving unit (RCU)

The RCU provides diversity reception functions, that is, the receiver consists of two

completely independent channels, and the input signals come from the main antenna

and diversity antenna. In complicated radio transmission areas where one antenna

receives very poor signal, the signal received from the other (diversity) antenna may

be of a better quality.

The BTS receives signals from both the main channel and the diversity channel, then

handles demodulation after combination algorithms. It can provide 3~5dB diversity

gain, thus improving the communication quality.

Each receiving channel consists of down conversion circuits. The received signals are

sent to the frequency mixer after filtering and amplification, so as to generate

intermediate frequency signals, which after further filtering and amplification aredirectly sent to the baseband unit for digital demodulation processing.

z Transmitter Driver and PLL unit (TDP)

This unit consists of 3 parts, transmitter excitation, frequency synthesizer, and PLL

testing.

Transmitter excitation unit directly modulates the I and Q signals sent from the

baseband unit through the orthogonal modulator into the radio signals for

transmission. This works rather simple and reliable.

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2-9

After modulation, the signal controlled by the APC provides the power amplifier unit

(PAU) with a certain power level.

The transmitter excitation unit also provides the dynamic and static power control at

the base station. Static power control (the maximum transmission power of the base

station) is specified during network planning. In contrast, dynamic power control is

performed during communication. Static power control has 0~10 levels (level 0 is

46dBm), decrementing by 2dBm each level. Dynamic power control has 0~15 levels,

decrementing by 2dBm each level.

To reduce noise in the radio environment and improves the network capacity and

service quality, the base station transmission power should be kept as low as possible

as long as the communication quality can be ensured. So each traffic channel is kept

at the lowest possible dynamic power level, with all idle channels transmission shut

down.

Moreover, transmitter excitation also provides the over-power alarm signal and

under-power alarm signal of the TRX. When the TRX output power is 3dB higher than

the specified level, over-power alarm will be generated. When the TRX output power

is 3dB lower than the specified level, under-power alarm will be generated.

Frequency synthesizer is the essential part of the whole transceiver. It generates

various local oscillation for the up/down frequency conversions, such as transmitter

local oscillation, receiver local oscillation, and PLL test local oscillation. Each of the

transmitter local oscillation and receiver local oscillation has two loops to achievehopping loop switchover.PLL testing is designed for TRX loopback testing. It attenuates part of the signals

coupled by the power amplifier output into the receiving frequency band through

frequency conversion, then sends them to the receiver after coupling. It is used to

check the TRX transmit channel and the receive channel.

z Power amplifier unit (PAU)

The PAU mainly performs radio signal amplification. Its maximum output power level

can be 46dBm or 47.8dBm. It also provides feed sampling signals controlled by the

transmitter APC, and the following alarm information:

z Over-temperature alarm, when the temperature of the power amplifier exceeds

85C, the power amplifier unit reports the high-temperature alarm via the

baseband unit, and automatically turns off the power amplifier.

z Over standing wave alarm, when the standing wave at the power amplifier output

end exceeds 3.5, it reports standing wave alarm to the baseband unit.

III. Interface

External interfaces of the TRX module includes:

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2-11

Input coupling & delay filtering

Amp. & phase control 60W power amplify

Power Synthesizer Module

Alarm collect & outputControl signal generation

Alarm Management Module

26V

26V

8V

8V

Alarm collectionPower amplify control

Alarm output

26V

TRXpoweroutput

PBU

CoupleOutput

PBU

poweroutput

Powermodule

Power

synthesize

andde

tect

Figure 2-6Functional blocks of PBU

The PBU couples the 40W power signals output from the TRX into main channel

signals and coupled channel signals. The main channel signals, after delay filtering,

enter the power synthesizer unit. The coupled channel signals are amplified into 60W

signals before being sent to the power synthesizer unit. To obtain final combined

signals, amplitude and phase control will be conducted on the 2 channels of input

signals.

The generation of control signals and the collecting/reporting of alarms are completedby the alarm management module. While the coupling, controlling and synthesizing of

power signals are performed by the power synthesizer module.

1) Power synthesizer module

Under the control of alarm management module, the power synthesizer module

amplifies TRX output signals, and at the same time provides power control and alarm

information, and alarm signals to the alarm management module, which detects

power amplification functionality and reports alarms.

2) Alarm management module

The alarm management module receives from the power synthesizer module the

power control and alarm information, and alarm signals. It is responsible for the

detection of power amplification functionality and the control over amplitude and

phase. It also reports the relevant alarms.

3) Power supply module

The power supply module supplies power to the power synthesizer module and the

alarm management module.

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2-12

2.3 Common Resource Frame

The common resource frame is the most import part of the cabinet. It includes 14

slots. Except for slots No.8 and No.9 which are reserved, other slots are respectivelyconfigured (from left to right) with PSUs (6 slots), PMU, TMU, TES and TEU.

Configurations of the TES and the TEU are optional.

2.3.1 PSU

PSU is a built in power supply module.

Depending on the power supply mode, BTS312 uses the power supply module of

different models. When 220V AC is adopted, the BTS uses the power supply module

with 220V AC input and +26V DC output. When +48V DC is adopted, it uses themodule with +48V DC input and +26V DC output. When +24V DC is used, no power

supply module is needed.

One PCU can supply power to two TRXs in N+1 flow-equalization hot-standby mode.

The working current of the module is 25A.

Note:For detailed descriptions, please refer to section 2.6, "Power Supply System".

2.3.2 PMU

I. General

PMU (Power Monitoring Unit) is close to the power supply module, managing the

power supply of the module. There are two types of PMUs: PMU for the DC/DC

module and PMU for the AC/DC module. The main difference between these two is

the battery management function. To reduce work load, both the AC/DC module and

the DC/DC module share one monitoring board.

II. Functions

Following describes the AC/DC module monitoring board.

1) Control

z Switch on/off of the power module (remote control available), with an output

signal of 12V/10mA

z Floating/equalizing charge of battery and current limit control

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2-13

z Connect/disconnect control of battery protection load, with a 230.5V output

low-voltage alarm, loading power-on/off condition

2) Switch signals

z

AC mains on/off signal and high-/low-voltage signal (12V/10mA)z Four fault status parameters (12V/10mA) provided to the monitoring board by 4

AC/DC modules

z Fan monitoring status parameters (normally, 12V/10mA)

z Fuse on/off status parameters of external battery (-0.3V

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2-14

2.3.3 TMU

I. General

TMU is located in the common frame of M900/M1800 BTS312. It is the timing,

transmission and management function entity of BTS312. It has the following main

functions:

z Provides channel multiplexing and flexible networking modes (including star-,

tree-, and chain- connections).

z Provides Man-Machine Interfaces (MMI) and operation & maintenance links for

software loading, fault management, configuration management, performance

management and security management, etc.

z Provides centralized BTS clock and its management, and clock hot standby

function.

z Provides alarm signal input ports, and handles external alarm collection and

control.

Two TMUs can be configured in the basic cabinet, providing clock source in hot

standby mode and serving to increase the number of E1 interfaces (each TMU

provides 4 E1 interfaces). In combined cabinet configurations, TMU boards are

configured in the basic cabinet only.

II. Structure and working principle

The functional blocks of the TMU are shown in Figure 2-8.

MCK

OMU

BIU

EAC

DBUS

CBUSMMI

BSC

MCK

Active TMU

Environment Monitors

Abis

TDU

Standby TMU

BIU

TBUS

Maintenance Terminal

RS485

External clock

BSC: Base Station Control TMU: Timing/Transmission and Management UnitBIU: Base Station Interface Unit OMU: Operation and Maintenance Unit TDU: Timing Distribution UnitEAC: External Alarm Collector MCK: Main Clock module DBUS: Data BusCBUS: Control Bus TBUS: Timing Bus

Figure 2-8Functional blocks of the TMU

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2-15

1) Base station interface unit (BIU)

The BIU handles conversion and reconversion between digital signals of the BTS

internal HWs and the HDB3 codes (on E1 lines). It switches timeslots on HW to

achieve flexible timeslot configuration, extracts superior clock signals, supportsexternal clock input, and outputs accurate clock signals through phase locking and

frequency division. It synchronizes internal bus data transmission, or generates

free-run clock signals when superior clocks are not available (due to E1 line or BSC

fault) to synchronize internal bus data transmission, and generates alarm and reports

them to OMU.

One BIU module can support a maximum of 4 E1 lines. The BIU modules on the two

TMU boards in one cabinet can be mutually extended, and the data on the 8 mutually

extended E1 lines can be freely switched. The E1 interfaces on the BIU module can

be respectively connected to the BSC or to the higher/lower level BTS to completestar, tree, and chain connections.

2) Operation and maintenance unit (OMU)

The OMU module is the core control and processing center of the TMU. Through the

OMU, performance parameters of various BIU and MCK units can be directly

configured.

The OMU receives fault alarms, handles fault management, and communicates via

internal control buses with the CPU of various units (TRX, CDU, PMU, TES, etc.) in

the BTS, so as to complete the operation and maintenance of the whole system.

It collectively loads and saves the software of various BTS units before loading

software for each unit according to demands. Moreover, it supports the Man-Machine

Interface (MMI) connecting to the PC.

The Flash memory of the OMU module can store two different versions of BTS

software. One is the software currently used by the BTS and the other one is the

previous BTS software. It can load either version according to the requirements to

each board.

When the software on the BTS needs to be upgraded, the new version can be loaded

from the BSC through OML and saved on the OMU to replace the old version.

Meanwhile, the OMU keeps the original software version of the BTS as a backup, in

case the loading should fail.

3) Main clock module (MCK)

The MCK is configured with an OCXO (oven controlled crystal oscillator) compliant

with the stratum 3 A standard, and phase-locking and frequency-division circuits.

According to system configuration, the MCK can work in the free-run mode or

software phase-locked mode to output a reference clock SREF with a stability better

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2-18

1) Power supply module

The power supply module of the TES board includes two parts, the DC/DC

conversion circuit and the DC/AC conversion circuit. The DC/DC conversion circuit

converts two +24V DC supplies into +5V DC and one +24V DC supply into 5V DC.The DC/AC conversion circuit converts +24V DC into 75V AC ringing current.

The ringing current is featured by high performance ringing current signal sources,

sine wave output, low distortion, light weight, and high power density. Its output

voltage is 75V AC, and its output current is 40mA, with a standard tone of 25Hz.

Note:Figure 2-9 shows that TES can provide power for 2 TEU boards. So one TEU board can be configured

in the 6 carrier cabinets of M900/ M1800 BTS312, and two TEU boards in 12 carrier cabinets.

2) Communication module

The main function of the communication module is to handle the communication

between TES and TMU, between TES and TEU, and to acquire the PCB version No.

and cabinet No. of the TES board.

The serial port communication between TES and TMU is implemented through

RS485 standard. TES is connected with CBUS3 via the level conversion circuit. The

serial port communication between TES and TEU adopts the point-to-point mode,

with the serial port level as the TTL level.

Communication with TMU mainly includes reporting transmission network information

and transmission board information from TEU to TMU, as well as reporting TES board

status information to TMU.

Communication with TEU is mainly to acquire transmission network and base station

transmission board information.

III. Indices

The board's size is 280mm233mm, occupying one standard board position.

2.3.5 ASU

Due to the complexity of network, the base station is required to support multiple

external interfaces and flexible networking modes.

Besides the E1 interfaces, M900/M1800 BTS312 also has the built-in transmission

system. It supports the 155M SDH optical interfaces. All these interfaces are provided

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2-20

z Orderwire: 1

z Ethernet interface: 1

z User RS232 port (point to point): 1

z

Network management interface: Ethernet/RS232

2.3.6 ABB

I. General

In practice, chain networking is usually adopted in BSS networking. This networking

mode has the advantage of simple structure and low cost, but also it has the

disadvantage that when power failure occurs at a site, all services of the downstream

sites will be interrupted. ABB provides of Abis interface bypass function as a solution

to the problem above.

II. Functions

ABB is applied in the environment of BTS chain networking. It is in charge of the BTS

transmission trunk. When power failure occurs at a certain level (in the middle) of

BTS in the chain networking, ABB will bypass the Abis transmission line off this site,

and directly connect it to the downstream BTS. In this way, even if power failure

occurs at the middle level site in chain networking environment, the services of the

downstream site will not be affected. See Figure 2-10.

BSCABB

TMU

ABB

TMU

ABB

TMU

Site1 Site2 Site3

Figure 2-10ABB working principle

ABB can also perform loop back at the transmission line, so that in the case of powerfailure at the last level BTS, ABB will loop back the E1 signal for BSC to detect the

quality of the entire transmission link.

III. Location of Board

ABB shares the same slot with TEU, therefore the size of the board and the interface

definition is consistent with TEU. BTS312 has two TEU slots, but ABB can only select

the TEU0 slot.

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2.3.7 ABA

I. General

ABA realizes the communication between ABB and TMU. ABB communicates with

TMU via CBUS3. But the slot of ABB does not provide the connection with CBUS3.

Therefore, ABA is used to provide the connection between them. Via ABA, part of the

signals from ABB (e.g. the signals of ABA on position) can be transmitted to CBUS3

on the backplane of common resource frame.

II. Location of Board

ABA shares the same slot with TES in BTS312, therefore the size of the board and

the interface definition is consistent with TES.

2.4 Other Parts of the Cabinet

2.4.1 TDU

The TDU is at the top of BTS cabinet, serving as the control center of BTS clock

transfer. It receives the clock source (SREF, OBCLK, FCLK, FN) from TMU, and

forwards the clock source to the TRXs in this cabinet and the parts in other cabinets.

TDU can also transfer other signals (e.g. alarm signals).

The main functions of the TDU are:

Provides bus-control interface

1) Clock Bus

In the simplex RS485 bus structure, it distributes the clocks generated by the active

TMU in the basic cabinet to various extension cabinets, The clock signal process is

shown in Figure 2-11.

TMU TDUBoards in the maincabinet

Boards in theextension cabinet

A-bis

Figure 2-11BTS clock signal process

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The TDU of each cabinet is connected to the bus. After receiving clock signals, it

transfers them to the TRX in the local cabinet.

The TDU of the last cabinet is connected to an adapter. All the TDUs form a

chrysanthemum ring of a clock bus, as shown in Figure 2-12.

UDC

UDC

U

DC

U

DC

U

DC

U

DC

M

P

P S UU U

T

XR

XR

XR

T

XR

P S U M

T T T

UDC

UDC

U

DC

U

DC

DC

DC

U U

UMP

U

M

T

Extension Cabinet Basic Cabinet

XR

XR

XR

T

XR

T T T

X X XR

T

XR

T T T

R R

X XR

XR

T

XR

T T T

XR

XR

XR

T

XR

T T T

X X XR

T

XR

T T T

R R

R

Figure 2-12Clock bus connection in a synchronous cell

2) Data Bus (DBUS)

DBUS is for the data connection between TMU and TRX. Each TMU provides 2 full

duplex DBUS link and TRX connection, called DBUS1 and DBUS2.

The physical feature of DBUS is differential RS485, TDMA synchronous bus and

distribution of 32 timeslots is similar to that of PCM.

The active TMU has DBUS connections to each TRX in the same cabinet. The active

and standby links are led from the main cabinet to the 24 TRXs in the local cabinet

group. There is no

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