System Description

M900/M1800 Base Station ControllerTable of Contents

Table of Contents

1-1Chapter 1 Introduction

Chapter 2 Network Architecture2-1Chapter 3 System Interfaces3-13.1 Abis interface3-13.2 Ater interface3-13.3 A-interface3-13.4 Interface with OMC and M20003-13.5 Interface with External CBC3-23.6 Pb interface3-2Chapter 4 M900/M1800 BSC4-14.1 Hardware Structure4-14.2 Cabinet Layout4-44.3 Technical Parameters4-84.4 Software Architecture4-94.5 Major Features4-104.6 Services and Functions4-124.7 Reliability4-13Chapter 5 M900/M1800 TCSM5-15.1 Hardware Architecture5-15.2 Major Features5-25.3 Cabinet Layout5-35.4 Technical Parameters5-45.4.1 System Capacity5-45.4.2 Physical Parameters5-45.4.3 Working Environment5-45.4.4 Input voltage5-45.4.5 Power consumption5-4Chapter 6 Compatibility6-1Chapter 7 Quality7-17.1 Hardware and Software7-17.2 Document7-17.3 Customer Service7-2Appendix A Abbreviations1

Chapter 1 Introduction

The objective of this document is to lay the foundation for understanding the Huawei M900/M1800 Base Station Controller (BSC). This chapter begins with an introduction to the Base Station Controller (BSC), Transcoder and Sub-Multiplexer (TCSM). Huawei M900/M1800 BSC fulfils the technical parameters indicated in the "PHASE 2/PHASE 2+" series of recommendations under the responsibility of the GSM Technical Committee of the European Telecommunication Standards Institute (ETSI).

Chapter 2 Network Architecture

The aggregate of the BSC and the attached BTSs are collectively referred to as the Base Station System (BSS). Huawei BSS consists of BSC, BTS and PCU. Despite the centralized control through OMC, local terminals are also provided to facilitate the on-site maintenance as shown in Figure 2-1.

Figure 2-1 Huawei BSS solution

Chapter 3 System Interfaces

The interfaces used in the BSC include the open interfaces and nonstandard interfaces defined in the GSM protocols. These interfaces include:

Abis interface

Ater interface

A-interface

Interface with OMC

Interface with external CBC

Pb interface3.1 Abis interface

The Abis interface in the BSS connects the BSC and the BTS. It is used to exchange voice frames, call control messages and BTS operation and maintenance information. Like other manufacturers Huawei has its own Abis interface but here comes the Huawei edge of future proof optical transmission technology between the BSC and BTS as well as the existing terrestrial links. M900/M1800 BSS offers up to 15 TRXs through one 2Mbit/s E1 link.

3.2 Ater interface

The Ater interface is a Huawei internal interface. The Ater interface connects the M900/M1800 TCSM and M900/M1800 BSC in the Huawei BSS. The physical interface consists of one or several E1 interfaces.

3.3 A-interface

The A-interface connects the BSC (TCSM) with the MSC. It supports voice/data traffic, BSS management, connection control, mobility management, supplementary services, short message service, dual-tone multi-frequency signaling.

3.4 Interface with OMC and M2000The implementation of OMC interface is based on the Operation and Maintenance framework of the ITU-T and the International Standards Organization (ISO). It is located between the BSC and Operation and Maintenance Center (Huawei OMC).

The interface is a Local Area Network (LAN) interface.

The PCU and BSC connect to the same OMC.The M900/M1800 BSC can be operated and maintained by OMC or by iManager M2000.

The iManager M2000 (M2000 for short) is a centralized operation and maintenance system developed by Huawei for the mobile communication network. You can centralize the management on the mobile communication network through the M2000.3.5 Interface with External CBC

This is a Huawei specific interface. The interface is a LAN/WAN/X.25 interface. It provides the possibility to connect with an external Cell Broadcast Center (CBC) of any vender.

3.6 Pb interface

The Pb interface connects the PCU and the BSC. Like other BSS systems available in market, Huawei has its own Pb interface, efficiently designed and implemented. The salient feature of the interface is flexible configuration of M900/M1800 PCU. PCU can be co-located at BSC or SGSN sites, even though it serves as part of BSS. The Huawei specific Pb interface satisfies all the standard requirements of BSC-PCU interface and implements management functions between the PCU and BSC for various kinds of shared resources such as cells, packet channels, E1 trunks and system messages. In addition, the Pb interface supports dynamic channel conversion, MS access on CCCH and so on.

Chapter 4 M900/M1800 BSC

The BSC performs radio-related functions including handover, radio network resources management, cell data management and so on. It also controls radio frequency power levels both in base stations and mobile stations. Physically the BSC is located between the MSC and BTS. A BSC serves one or more BTSs through the Abis interface. One or more BSCs are linked to one MSC through the A interface, that is, a BSC acts as a concentrator for the links between the Abis interface and A-interfaces.

The beauty design of the M900/M1800 BSC is its modularized approach, which saves a prominent amount during technology cycle because of system flexibility. A modularized design makes it easy to upgrade the software and hardware. It also improves the system reliability. Thanks to the Huawei modularized design. It is not a must any longer for a carrier to buy the whole system, as the carrier now can choose to place the order as demands grow. The carrier can expand its network from one BTS to 512 BTSs or a single TRX to 1024 TRXs by simply installing one BSC. The only thing to do is to add modules. The overall structure of a BSC is to be made clear before proceeding further.

4.1 Hardware StructureAccording to the hardware system a multi-module BSC can be divided into Administration Module/Communication Module (AM/CM), Basic Module (BM) and cell broadcast database (CDB). Figure 4-1 shows the structure of a multi-module BSC.

Figure 4-1 Hardware structure of a multi-module BSC

I. AM/CM

An AM/CM cabinet consists of communication control unit, central switching unit, transmission interface unit, clock synchronization system and alarm system. The BAM and CDB are also installed in the same cabinet.

In the communication control frame, the communication and control board is the main unit. This board controls different types of processing and functions in a centralized manner. Depending on the software loaded and DIP switch settings, the communication and control boards are named GMCCM and GMCCS. The GMCCM supports the following functions:

Communicates with the GSNT, GCTN, GALM and BAM through HDLC links

Transfers control information between the BM and TCSM units Controls the GSNT to provide software loading channels between the BM and the boards in the AM/CMA GMCCS provides signaling transmission links between the AM/CM and BM. It controls intra-module signaling and forwards the control message between BMs, from BM to GMCCM, from BM to GCTN and from BM to the TCSM unit. For system reliability these control boards are configured with proper redundancy.

The GCTN provides 16K16K switching. It receives the clock synchronization signals from the clock frame and distributes the clock to the GMCC, GALM, GSNT, BM and BAM. The GSNT supports 2K2K switching. All the communications between the AM/CM and BM is made through optical fiber interfaces, which are provided by GFBI boards. Each GFBI board provides two interfaces. The backplane GFBC converts optical signals into electrical signals and vice versa. The E3M board provides external interfaces for TCSM connections. The GALM board handles different types of external and internal alarms. The clock synchronization system controls the system clock. A GCKS is inserted in the clock frame of the basic cabinet. Two GCKS boards are required to ensure system protection.

II. BM

The previous text has introduced the BSC in terms of its structure and control system. The BM is also discussed in detail. Here we will see the difference of BM configuration in multi-module BSC. From above text we also know that in multi-module BSC communication, CDB and BAM are installed in AM/CM cabinet so there is no need to install these frames in BM cabinet. The only additional hardware needed is for the communication between BM and AM/CM. This communication is performed by GOPT.

III. Back administration module (BAM)

The BAM serves as the bridge for the communication between the BSC and OMC. In M900/M1800 BSC, BAM communicates with the control system via HDLC link and with the OMC server through LAN or WAN. Via BAM, the OMC can perform operation and maintenance over BSC.

IV. CDBThe CDB provides an interface between the BSC and CBC. It forwards the messages from the CBC to BSC. Then the BSC controls the messages and sends the received message to BTS as required while BTS performs load control. These messages are broadcast in a specific PLMN area or a cell. The CDB and CBC are connected through Ethernet.

V. Transcoder and Sub-Multiplexer (TCSM) unitThe TCSM unit provides the function of transcoding/rate adaptation and sub-multiplexing. A TCSM unit contains transcoder and rate adaptation unit (TRAU) and sub-multiplexer (SMUX). Although the SMUX is logically part of the BSC, but it is usually located at the MSC to save transmission media.

VI. Clock synchronization system

The clock synchronization system mainly comprises clock frame. It extracts clock either from the higher level (MSC) or BITS as a reference clock source. Stratum 3 clock is used as an international standard for the BSC system.

VII. Alarm system

The alarm system of the BSC collects distributed alarms and performs centralized processing. It sends various alarm messages to the alarm box and the OMC alarm system to alert the maintenance staff about runtime errors so that the system performance can be stable and well maintained.

4.2 Cabinet Layout

A multi-module BSC consists of multiple BMs and one AM/CM. Eight BMs can be installed in four BM cabinets and the AM/CM is configured in the AM/CM cabinet. Both cabinets have the same dimensions. Each cabinet contains six frames, numbered 05 from the bottom up. The AM/CM cabinet contains clock synchronization frame (frame 5), communication control frame (frame 4), transmission interface frame (frames 3 and 2), CDB (frame 1) and BAM in frame 0. Because the clock frame, BAM and CDB are installed in the AM/CM cabinet, the only device to be installed in the BM cabinet is the central processing frame and BIE. Figure 4-2 shows an AM/CM cabinet/frame/board configuration of a multi-module BSC.

Figure 4-2 AM/CM cabinet/frame/board configuration

A BM cabinet under full configuration contains two BMs in a multi-module BSC. Figure 4-3 shows the BM cabinet/frame/board configuration (full configuration) of a multi-module BSC.

Figure 4-3 BM cabinet/frame/board configuration

4.3 Technical Parameters

Multi-module BSC

I. Frequency bandsFrequency bands supported: 850 MHz, 900MHz, 1800MHz, 1900 MHz.II. System capacityDepending on requirements and the number of installed BM, cabinets (1 to 5) can be configured in multi-module BSC It can support 1024 TRXs or 512 BTSs at the most, with the following interfaces:

256 Ater interfaces

512 BTS

16 SS7 ports

1536 LAPD

64 Pb interfacesWhen Half Rate function is configured, the whole BSC can support 512 TRXs to 1024 TRXs.

When all TCHs are configured with Half Rate, the entire BSC can support 512 TRXs.III. System load Traffic load in busy hour: 6400 Erl (0.1% block rate)

Processing capability in busy hour: 800K-BHCA

IV. System clock

Min. accuracy: ( 4.6(10-6

Maximum frequency deviation: ( 2(10-8V. Physical

For one cabinet:

Height: 2,100 mm

Width: 880 mm

Depth: 550 mm

Weight (fully configured): 310 kg

VI. Working environment Floor bearing capacity: ( 450 kg/m2

Operating normal temperature: 1535oC

Operating safe temperature: 045oC

Operating normal humidity: 3065%

Operating safe humidity: 1090%

VII. Input voltage

The input voltage ranges from 57 V DC to 40 V DC.VIII. Power consumption

Fully configured AM/CM cabinet: 500 W

Fully configured BM single module: 350 W

Fully configured BSC (AM/CM+8BM): 3300 W

Fully configured TCSM unit: 1320 W

4.4 Software Architecture

The distributed control and centralized database software design of the M900/M1800 BSC ensures high reliability and efficiency. The self-designed dynamic control algorithms are implemented intelligently and provide a compact system and relatively fast execution of the events such as channel management, handover decision and power control functions.

The software system of the M900/M1800 BSC has excellent expandability. Software optimization helps to enhance the processing capability of the host, which ensures a reliable functioning of multi-module BSC. The software system of the M900/M1800 BSC has strong protections against errors. Carrier frequency mutual assistance is developed and implemented to enhance the fault tolerance of the BSC system software. Full backup protection, traffic control, and resources check better the system reliability.

Its rich Operation and Maintenance functions allow a user to control and manage various functions remotely through OMC. It provides visual graphic interfaces through OMC, which helps to monitor the network and in case of any abnormality, take spontaneous actions. It provides dynamic data configuration through which maintenance staff can block a device without any effect on the current subscriber's call. The host software in the software system can be loaded from the BAM into the memory of the GMPU boards and backup software can be stored in the Flash Memory of GMPU. The running software of the boards is stationed in respective CPUs. During system upgrading, related software can be loaded through OMC without affecting the normal operations of other parts, which ensures rapid and easy upgrading of software version. Figure 4-4 shows the software architecture of M900/M1800 BSC.

Figure 4-4 Software structure of the BSC4.5 Major Features

M900/M1800 BSC is a complete and cost-effective solution supported by highly integrated system elements. Reliable design, powerful functions and flexible expansion ensures its popularity. The following describes some of the functions of the BSC.

I. GPRS/EGPRS on air

The M900/M1800 BSC supports GPRS/EGPRS services, a way towards to 3G mobile communication standards. It also provides data services to end users.

II. Standard and compatible interfaces

The interfaces of the BSC support 2Mbit/s E1. The M900/M1800 BSC provides standard A-interfaces so that it can be easily deployed in any cellular network, and supports Abis and Pb interfaces to BTS and PCU respectively. On the Abis interface, each E1 can provide maximum transmission capacity of 15 TRXs.

III. High integration and small floor space

Because of its modular approach, only four cabinets are required to contain eight BMs, which provide the compact system that demands less installation space.

IV. Low power consumption

Only five cabinets are needed to contain 1024 TRXs, reducing power consumption.

V. Flexible BTS networking structure

The M900/M1800 BSC can support different transmission networking modes to configure the BTS, which will be discussed in detail latter.

VI. Large capacity and strong processing capability

The M900/M1800 BSC is designed for both small and large capacity networks, which means fewer BSCs and less investment.

VII. Easy expansion

Modular structure enables the on-line smooth expansion i.e. no need to interrupt the systems running services.

VIII. Centralized monitoring

The M900/M1800 BSC gives a complete and powerful system monitoring system so that the performance of the system can be checked continuously. This enhances the network reliability.

IX. Error code test on Abis interface

The error code transmitted across the Abis interface between BTS and BSC can be detected by making use of traffic statistic function, which implements the main functions of error code tester. In addition, the time and location of the testing is not limited.

Implementation Plan: A statistics can be made on the link layer message of Abis interface up/down links and the transmission frames of the physical layers via the task of LAPD Protocol Performance Measurement on BSC traffic statistic console.

X. Subscriber-based message tracing function

The message is originated from the BSC maintenance console. The signaling, including the signaling of A-interface, Abis interface and Um interface, of certain special subscribers can be traced. You can input the keywords (such as, IMSI, TMSI, MSISDN, and IMEI) to trace the target user. If the users information in the call signaling matches that of the expected user, the signaling after this call is returned to OMC and displayed.4.6 Services and Functions

The M900/M1800 BSC supports the following services and functions:

Supports P-GSM, E-GSM, R-GSM, DCS1800 frequency band as ETSI GSM protocol mentioned.

Provides all functions for BTS supervision, which is stipulated in the GSM specifications. Self-designed intelligent algorithms ensure the reliability especially SDCCH dynamic allocation. Location updating, call connection, short message, message on demand and SMS-based WAP use the signaling channels and their traffic is gradually increased. The SDCCH dynamic allocation function enables the real time dynamic adjustment of the SDCCH and TCH ratio depending on the radio environment, and improved Quality of Service (QoS) as a result. Support eMLPP (Enhanced Multi-Level Precedence and Pre-emption service). Supports the broadcasting of short messages in the cell. Weather reports, advertisements, stock, banking, traffic information can be transmitted to MS through broadcast control channel.

Supports smooth channel assignment during the call set-up requested to or from the MS, support re-assignment.

Supports, call handling, Full Rate (FR), Enhanced Full Rate (EFR) and Half Rate (HR) voice coding. It also offers Very Early Allocation (VEA), Early Allocation (EA) and Off-air Call Set Up (OACSU) mode.

Supports discontinuous transmission (DTX) and Voice Activity Detection (VAD) implementation.

Encryption is used for ciphering and deciphering of information to and from an MS over a dedicated resource to provide security. Encryption is used or not by BTS but BSC provides this control.

Provides paging queuing and call queuing function.

With the help of different parameters and reports monitors the states and status of radio channels.

To reduce the radio channel interference and maximum network utilization it supports both baseband and synthesizer hopping.

Traffic statistic reports are used to increase the system efficiency and helps in network optimization.

High integration of TC supports all standard services.

To provide a continuous conversation when roaming is the core objective of a cellular network. When a user moves from one BTS to another, the call is handed over to a new BTS so that there will be no interruption.

Supports hierarchical cellular network structure. The radio network is divided into 4 layers, each layer can be divided into 16 priorities to control the traffic distribution. Supports GSM900/GSM1800 co-BCCH, which means frequencies in GSM900 and GSM1800 can be configured into one cell.

Power Control is an important feature to improve the transmission quality by reducing interference. It also prolongs the battery lifetime.

Operation and maintenance: Powerful tools on management, which provides easy maintenance of OMC-R link, BTS and BSC fault management through OMC or local terminal.

Supports Integrated network management interface of OMC, it includes integrated network management interface of statistics and integrated network management interface of alarm. OMC-R supports Dynamic Data Configuration for BSS, which provides GUI interface for Data configure.

Supports Data configuration and BTS smooth software down loading.

Supports 16kbit/s RSL and OML on Abis interface

Supports 64kbit/s semi-permanent connection from BTS to BSC or from BSC to MSC.

Supports multiple MNC functions Supports star, tree, chain and ring topologies on the Abis interface for site connection.

Supports Enhanced Data rates for GSM Evolution (EDGE). The 4 16kbit/s links for MCS1-9 of EGPRS (Enhanced GPRS) are supported and dynamic conversion between these modes can be made based on the BEP (Block Error Probability) report from the mobile and radio transmission quality. Supports Adaptive Multi Rate (AMR). Allow the BTS and the MS automatically select the proper Codec algorithm based on the actual radio environment to adjust the Codec rate and finally improve the voice quality. Support 3-digit MNC. All the cells (including external cells) within BSC can be configured with 3 -digit MNC and 2-digit MNC. The local MNC can also be configured as 3-digit or 2-digit. The user can configure it flexibly with no limitation. Support LCS function based on CELL ID+TA of BSS. Huawei BSS can implement the BSS-based CELL+TA mobile location service. Cell ID + TA location is to use current parameter TA to estimate the distance between MS and BTS, thus raises the location precision on the basis of Cell ID. Huawei BSC integrates Service Mobile Location Center (SMLC). The interface between BSC and SMLC is the internal interface. The location precision of this scheme is about 500m. Support User Signaling Tracing. Input the user characteristic (such as IMSI, TMSI, MSISDN, and IMEI) through the BSC OMC, and the host decodes the signaling of the call and then compares the characteristic in the signaling with the input characteristic. If the they match, the host returns the signaling of the call to the OMC to display. This function can trace, save and review the signaling on the A interface and Abis interface. It can trace 16 users at the same time.It can also trace the A interface or Abis interface of a user.When trace the message on the Abis interface, you can choose whether to trace the measurement report. When the intra-BSC handover occurs, this function informs the target BM to continue to trace the user through BSC.4.7 Reliability

The M900/M1800 BSC is designed to meet the availability requirements of the ITU-T. The following design objectives have been adopted to ensure that the availability of the BSC is very high.

Simplicity and speed of the maintenance procedures are the prerequisites for the availability of the M900/M1800 BSC. The maintenance is improved by the modular structure of the equipment, automatic fault detection procedures, and elimination of downtime by using a hot-standby or load-sharing unit in the event of a failure.

The following design objectives have been adopted to ensure that the unavailability of the BSC is very low.

Reliability parameter:

MTBF (mean time between failures): 341298 hours MTTR (mean time to repair): 1 hour

Availability: 99.9997%

Mean time of system down per year: 0.026 hoursI. Reliability Measures

Hot-standby or load-sharing working mode is adopted for important unit. All vital or important component of BSC are duplicated and mechanisms are included providing for automatic reconfiguration in the event of failure. The switching module, operation and maintenance module, base station interface equipment, LAPD and SS7 procession module etc are design in hot standby and load-sharing working mode to ensure high reliability.

II. Performance Measurement

OMC supports comprehensive network statistics and observation reports for short- and long-term trend analysis purposes. By the excellent data of statistics, the customer can decide the optimizing method easily.

The BSSOMAP module accepts performance measurement tasks started by the OMC traffic statistics console and schedules them centrally. It notifies the relative modules to start/stop measurement, eventually collects and processes measurement results, and send the result to the OMC statistics console.

Performance measurement tasks have absolute time life cycle and statistic cycle attributes. For example, a performance measurement task on a cell starts on July 6, 1998. The statistics life is 60 days. The measurement is conducted between 9:00 am to 14:00 pm with 5 minutes cycles. The task scheduling is hence driven by the absolute timer in the system.

Results of the measurements are sent to the OMC traffic statistics console once a second with the resending acknowledgment message. The customer performs the tasks through OMC traffic statistics console.

III. Traffic Control

Traffic control of the M900/M1800 BSC includes traffic control inside the system and on the Abis interface.

Internal traffic control conducts traffic control over the whole BSC based on the GMPU loading software and its processing capacity. The internal traffic control monitors key system resources including CPU loading, message queues and evaluates system flow level.

The traffic control on the Abis interface is exercised specifically over the loading of radio resources, based on the cell so as to reduce traffic volume at the source. The traffic control on the Abis interface handles the overload messages from the Abis interface, calculates the flow level in the cell, and provides appropriate control over the access of the MS in the cell.

Design of internal traffic control

Traffic flow is classified into 12 levels. The higher the flow level is, the lower the service level.

Level 0 is a normal running level; levels 1-11 are flow levels for the BSC traffic control. At different levels, the module provides different levels of service. When traffic control exists in the BSC system (traffic control level is higher than 0), packet service access is prohibited

Design of traffic control on the Abis interface

Traffic is classified into 12 levels, with cell as the smallest control unit. The higher traffic level means lower service level.

Level 0 is a normal running level, levels 1-11 are the flow level for certain cell. At different flow level, the cell provides different service level. When there is traffic control (traffic control level is greater than 0) in a cell, new packet service access is prohibited.

IV. Resources Check

The resources check function of the M900/M1800 BSC ensures reliable system running by providing powerful self-test for faults and recovery functions. This function automatically corrects the running errors that can take place in various abnormalities, check the usage of system resources, and ensures correct allocation, use, and release of various resources. To prevent the accumulation of errors generated during the long-term running of the system that can lead to deterioration of system processing capability, the function corrects various faults so as to ensure the reliable running system.

Resources check initiated by the BSC

This function is dispatched by the CHECK software module, and conducted in the various modules. It can be performed in two ways i.e. checking initiated at the maintenance console and timed resources check every day. It mainly involves:

Check the usage of the memory resources, for example, allocation and release of the call control block.

Check the usage of A-interface circuit resources.

Check the consistence between radio resources occupation and state.

Check the usage of GNET board resources.

Check the consistence between the signaling link occupation and state.

Miscellaneous, check the consistency of the system controls parameters.

Resources check initiated by the PCU

To eliminate the inconsistency between the PCU and BSC due to certain abnormalities, it is necessary to check resources periodically between the BSC and PCU. The check is initiated by PCU, and BSC is responsible for correcting the inconsistency between the two entities. The check mainly involves:

Check the type and state of PDCH channels

Check the PCIC states.

Check the cell states.

Chapter 5 M900/M1800 TCSM

Huawei TCSM units are functional units of the BSC. A TCSM can be located either at the BSC or MSC site. Sub-multiplexing is used between the BSC and TCSM to reduce transmission costs. Sub-multiplexing also reduces the amount of PCM lines needed between the MSC and the BSC sites.

TCSM converts the 64 kbit/s traffic channels arriving from the MSC into 16 kbit/s or 8 kbit/s channels and multiplexes these channels to fit the PCM line time slots going towards the BSC. The same principle in reverse applies in the other direction and vice versa.

Although TCSM units is the functional part of BSS but usually it is located at the MSC end, this results in four times the standard PCM capacity in terms of traffic. Since the rate of each channel of existing terrestrial lines is 64kbit/s, it is a waste if one channel is used to carry one 16kbit/s GSM channel. To save terrestrial line resources, sub-multiplexer (SMUX) is generally used between MSC and BSC to multiplex 416kbit/s channels to transmit four-voice channels through one terrestrial line channel.

In general TRAU and SMUX are integrated in one unit called TCSM i.e. it handles both rate conversion and multiplexing simultaneously.

5.1 Hardware Architecture

In M900/M1800 multi-module BSC, FTC board accomplishes functions of TRAU and MSM and E3M together boards accomplish functions of SMUX. MSM is configured on TCSM/MSC side and E3M is on BSC side. The frame where FTC and MSM boards are installed/inserted is called TCSM frame. Four MSM boards and 16 FTC boards can be plugged in 1 TCSM frame.

The multi-module BSC uses the E3M board in AM/CM module to perform rate adaptation function for BSC.

Figure 5-1 Multi-module BSC with TCSM units

5.2 Major Features

Compact and intelligent design of a TCSM provides easy control and maintenance. Huawei TCSM has the following salient features.

The most fundamental function of TRAU is to encode and decode voices. Regular Pulse Excitation Long Term Prediction (RPE-LTP) algorithm is used. (EFR service adopts CELP algorithm). After the addition of synchronous bits and command words, a frame signal of TRAU has 320 bits. The reverse process of coding is called decoding. After receiving TRAU frame from BSC direction, TRAU will restore it to voice data by decoding algorithm and send to the MSC. The TRAU functions are performed by FTC board.

Voice Activity Detection (VAD) is used together with Silence Descriptor (SID) technique in the discontinuous transmission (DTX) mode of GSM. If TRAU detects that there is no voice information in the data received from MSC through VAD functional module, it will clear voice flag in the encoded TRAU frame. After BTS identifies this flag bit, transmission of downlink will be disconnected till the flag resets. In the same way, TRAU identifies SID flag at the reception of uplink frame.

TRAU provide a transparent data transmission. GSM data services includes the transmission of various data messages e.g. text, image, fax, computer files etc. During data service communication, TRAU accomplishes the format conversion of data frame and rate adaptation without transcoding for transferred data.

Huawei FTC board transmits the signaling on a time slot without any processing and SMUX can transparently transfer one channel of signaling so that signaling information will not be effected.

TRAU provides powerful operation and maintenance functions. MSM board and E3M/SMI can communicate with each other through HDLC link, which occupies the last two bits of 31st timeslot on E1 link. BSC can operate and maintain the remote TCSM units through this HDLC link.

Huawei TCSM can multiplex 430=120 voice channels to 1 standard E1 link and de-multiplex 120=430 voice channels from 1 standard E1 link.

TRAU is compatible with Full Rate (FR), Half Rate (HR) ,Enhanced Full Rate (EFR) and Adaptive MultiRate (AMR).

5.3 Cabinet Layout

Figure 5-2 shows the TCSM cabinet/frame/board configuration.When a TCSM is configured at the BSC side, TCSM frame is generally installed in the same cabinet with BM.

Usually, the TCSM is configured at the MSC side to save the transmission resources,.

Figure 5-2 Fully configured TCSM cabinet

5.4 Technical Parameters

5.4.1 System Capacity

Single TCSM cabinet supports:

24 TCSM units

96 (E1) A-interfaces

24 (E1) Ater interfaces

5.4.2 Physical Parameters Height: 2,100 mm

Width: 840 mm

Depth: 550 mm

Weight (under full configuration): 310 kg

5.4.3 Working Environment

Floor bearing capacity: ( 450 kg/m2

Operating normal temperature: 1535oC

Operating safe temperature: 045oC

Operating normal humidity: 3065%

Operating safe humidity: 1090%

5.4.4 Input voltage

The input voltage ranges from 57 V DC to 40 V DC.5.4.5 Power consumption

The power consumption of a fully configured TCSM cabinet (containing 6 frames) is 1320 W.Chapter 6 Compatibility

Huawei M900/M1800 GSM system complies with ETSI standard and relevant protocols. Huawei M900/M1800 BSS is based on the GSM technical parameters set by the European Telecommunications Standards Institute (ETSI). These technical parameters are designed to ensure inter-operability of equipment from different manufacturers in the same GSM network.

Huawei M900/M1800 BSS is not only compatible with Huawei M900/M1800 Network Switching Subsystem (NSS) and GPRS Switching Subsystem (GSS), but also compatible with the major switch suppliers.

The A-interface is an open interface. Huawei has accomplished intensive testing concerning the A-interface. Huawei has tested the M900/M1800 BSS with all the major switch suppliers on the market. Huawei BSS has been proved to interwork with other manufacturers' MSCs such as Nokia, Alcatel, Siemens, Ericsson and Nortel etc.

Huawei self-developed 3G system will fully support the smooth evolution from GSM/GPRS/EDGE to 3G.

Chapter 7 Quality

In order to maximize service quality and to run the network effectively, the equipment and software must be planned and produced according to specific quality standards.7.1 Hardware and Software

The hardware of equipment goes through a comprehensive commissioning, integration and system testing before being delivered to customers. The modularity of the equipment and the use of a hot standby unit in the event of a failure enhance equipment reliability. All critical functional elements use 2N or N+1 redundancy method to maximum the reliability.

In different phases the software of equipment goes through such as comprehensive testing, reviews and inspections, etc. The procedures, methods, tools and modularity design enables high quality control.

In order to guarantee the quality to products and satisfaction to customers, capability maturity model (CMM), which was put forward by American software engineering institute (SEI), has been applied to software development course. The core of CMM is to put the concept, capability, expression and maturity of the software process together to implement the controllability of software production and quality. It is just the advanced software development thought that makes Huawei system software development be in invincible position.

At the hardware designing, Huawei widely makes use of the 0.35 m ASIC technology, for which Huawei holds independent intellectual property rights, to greatly improve the integration level of the products and decrease the dimension and power consumption of the products. Comparing with same products of other corporations, the power consumption is curtailed by 30% and the dimension is curtailed by 40%. Huawei promises to provide more excellent products to customers.

7.2 Document

Huawei documentation goes through several procedures such as reviews, inspections and testing in its development to ensure the quality. The terminology used in Huawei document is based on the recommendations of ITU-T and the applicable standards of ETSI, ICE, ISO and GSM Phases.

Huawei provides electronic and paper format Documentation for customer browsing.

7.3 Customer Service

Ensuring high quality of maintenance, service and good network performance, Huawei customer service department provides the customer with a comprehensive set of network planning, analysis, training and development services.

Appendix A Abbreviations

AbbreviationFull text

A

AM/CMAdministration Module/ Communication Module

AMR Adaptive Multi Rate

APLAdvanced Phase Lock

B

BAMBack Administration Module

BCHBroadcast Control Channel

BERBit Error Rate

BEPBlock Error Probability

BHCABusy Hour Call Attempt

BIEBase station Interface Equipment

BMBasic Module

BSCBase Station Controller

BSSBase Station Subsystem

BTSBase Transceiver Station

C

C/ICarrier/Interference

CCCHCommon Control Channel

CDBCentral Database

CDMACode Division Multiple Access

CDUCombiner and Divider Unit

CELPCode Exited Linear Predictive Coding

CPUCentral Processing Unit

CSCoding Scheme

D

DCDirect Current

DCHDedicated Control Channel

DSPDigital Signal Processor

DTXDiscontinuous Transmission

E

EAEarly Allocation

EDGEEnhanced Data rates for GSM Evolution

EFREnhanced Full Rate

EGPRSEnhanced GPRS (General Packet Radio Service)

eMLPPEnhanced Multi-Level Precedence and Pre-emption service

F

FRFull Rate

FTTBFiber To The Base station

G

GALMAlarm Board

GCKSClock Board

GLAPLAP Board

GMCCMModule Communication and Control Board

GMEMMemory Board

GMPUMain Processing Unit

GMSKGaussian Minimum shift Keying

GNODNode Control Board

GOSGrade of Service

GPRSGeneral Packet Radio Service

GSMGlobal System for Mobile Communication

GSNTSwitching Board

H

HSCHot Swap Control

L

LANLocal Area Network

LAPDLink Access Protocol D

LMTLocal Maintenance Terminal

M

MFUMicrocell Frame processing Unit

MMIMan Machine Interface

MMUMicrocell operation and Maintenance Unit

MPAMicrocell Power Amplifier

MSMobile Station

MSCMobile Switching Center

MTBFMean Time Between Failures

MTRMicrocell Transceiver Unit

N

NSSNetwork SubSystem

O

O&MOperation and Maintenance Center

OACSUOff Air Call Set Up

OMCOperation and Maintenance Center

P

PCMPulse Code Modulation

PCUPacket Control Unit

PDNPublic Data Network

PLMNPublic Land Mobile Network

PMUPower Management Unit

POMUPacket Operation and Maintenance Unit

PSTNPublic Switched Telephone Network

PSUPower Supply Unit

R

RFRadio Frequency

RPE-LTPRegular Excitation Long Term Predictor

RPPURadio Packet Processing Unit

S

SCPSignaling Control Processing

SGSNServing GPRS support Node

SIDSilence Descriptor

SMISub Multiplexer Interface

SMCShort Message Center

SMSShort Message service

SMUXSub Multiplexer

SS7Signaling System 7

T

TCHTraffic Channel

TCSMTranscoder and Sub Multiplexer

TDMATime Division Multiple Access

TEUTransmission Extension unit

TMUTransmission Management Unit

TRAUTranscoder and Rate Adaptation Unit

V

VADVoice Activity Detection

VEAVery Early Allocation

VLRVisitor Location Register

VLSIVery Large Scale Integration

VSWRVoltage Standing Wave Ratio

W

WANWide Area Network

WAPWireless Application Protocol

WCDMAWide band CDMA

X

xDSLx Digital Subscriber Line or x Digital Subscriber

1i