GSM Base Station Subsystem

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รายงานการฝกอบรมหลักสูตร GSM BSS

สวนที่ 1 ขอมูลทั่วไป

รายชื่อพนักงานที่เขารับการฝกอบรม 1.1 นายสมพงษ จันทรวานิตย ผส.8 สร. 1.2 นายชัยวฒัน สุขเมฆ วศก.8 ทร. 1.3 นายวีระ ทองไพบลูย วศก.8 ทร. 1.4 นายสุรพงศ ระวงัวงศ วศก.8 ทร. 1.5 นายวิโรจน แดงเจรญิสุข วศก.7 นข. 1.6 นายนวิัฒน คุณกันหา นทค.7 ขต.(อน) 1.7 นายไพโรจน ปลองมาก นทค.7 ขต.(ตต) 1.8 นายสทุธชิัย จัตวาภักด ี นทค.6 ขต.(อ) 1.9 นายโกศล รัตนสวางวงศ นทค.6 ขต.(ต) 1.10 นายพรชัย ตรงตระกูล นทค.6 ขต.(ก) 1.11 นายบุญโชติ แกวเทพ นทค.6 ขต.(น) 1.12 นายศรีเกษม ภุมรินทร ชทค.4 ทร.

หลักสูตรที่เขารับการฝกอบรม ชื่อหลักสูตร (ภาษาไทย) ชื่อหลักสูตร (ภาษาอังกฤษ) GSM BASE STATION SUBSYSTEM เพื่อ ฝกอบรม แหลงใหทนุ บริษัท ทรู มูฟ จํากัด ประเทศที่ไป จีน ระหวางวันที่ 22 พฤษภาคม 2552 – 20 มิถุนายน 2552 ภายใตโครงการ สัญญาดําเนินการใหบริการวิทยุคมนาคมฯระหวาง กสท กับ บริษทั ทรู มฟู จาํกดั

สวนที่ 2 บทคัดยอ ตามสัญญาใหดําเนินการใหบริการวทิยุคมนาคมระบบเซลลูลา DIGITAL PCN 1800 ระหวาง กสท กับ บริษัท ทรู มฟู จาํกัด ขอที ่ 15.3 ระบุให “บริษัทจะตองจดัการฝกอบรมดานเทคนิคทั้งหมดใหแกเจาหนาที่ของ กสท. จํานวนไมนอยกวา 24 คน กบับริษัทผูผลิตเครื่องและอุปกรณในตางประเทศเปนระยะเวลาไมนอยกวาคนละ 30 วัน” และ 14 พฤษภาคม 2552 กสท. ไดอนุมัติใหพนักงานจํานวน 12 คน

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เขารวมการฝกอบรมดานเทคนิคตามสัญญาดําเนนิการดังกลาว ในหลักสูตร GSM BSS AND WCDMA โดยรายละเอยีดเนื้อหาหลกัสูตรประกอบดวย

• GSM BSS เนื้อหาประกอบดวยโครงสรางพื้นฐานของโครงขายระบบเซลลูลา GSM ต้ังแต Interface,

Protocols, Numbering plan, GSM Radio technologies, Signaling ตางๆ และในสวนของอุปกรณ BTS และ BSC ไดฝกอบรมทั้ง Operation and Maintenance Training ในสวนของ Software Maintenance ไดฝกอบรม Software BSC6000 ซึ่งเปน Software OMC ของ Huawei ที่ใช Maintenance สถานฐีานและ BSC

• PCU เนื้อหาประกอบดวย Operation and Maintenance PCU ซึ่งเปนระบบการใหบริการ Data บน

โครงขาย GSM • WCDMA

เนื้อหาประกอบดวย 3G Overview, CDMA principle, WCDMA Fundamental ตลอดถึง Hardware System Structure และ Hardware ที่เปน BSC และ BTS ยี่หอ Huawei ที่ใชงานในปจจุบัน

สวนที่ 3 ขอมูลที่ไดรับ

3.1 วัตถุประสงค 1) เพื่อใหบริษทัผูรับสัมปทานปฏิบัติตามสัญญาดําเนนิการใหบริการ 2) เพื่อใหพนกังาน บมจ.กสท โทรคมนาคม ไดมีความรูความเขาใจ ในเรื่อง

เทคโนโลยีการใหบริการเซลลูลา GSM มากขึ้น 3) เพื่อใหพนกังาน บมจ.กสท โทรคมนาคม ไดศึกษาดูงานยังบริษทัผูผลิตอุปกรณ

โครงขายโทรคมนาคม 4) เพื่อใหพนกังาน บมจ.กสท โทรคมนาคม ไดรับความรูเกี่ยวกับเทคโนโลย ี

Mobile สมัยใหมเพิ่มมากขึน้ 3.2 เนื้อหาทีเ่ปนสาระสําคัญดังตอไปนี้

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GSM Base Station Subsystem

1. บทนํา

โทรศัพทเคลื่อนที่ระบบ GSM มีโครงสรางของโครงขายเพื่อการใหบริการดังภาพที ่ 1 โดยจําแนกตามหนาที่ของอุปกรณออกเปน 3 สวนหลกั คือ

• MS (Mobile Station) เปนสวนติดตอกับผูใช (Subscriber) • BSS (Base Station Subsystem) มีหนาที่จัดการและบริหารความถี ่RF เพื่อติดตอกับผูใชงาน

ผานทาง MS เชื่อมตอสัญญาณ Base Band ไปยัง Core Network เพื่อทาํการหาเสนทางการเชื่อมตอไปยังผูใชปลายทางตอไป

• NSS (Network Station Subsystem) ทําหนาทเีปน Circuit Switching สําหรับบริการประเภท Voice, Package switching สําหรับบริการ Data และ Network Interconnector สําหรับการเชื่อตอกับโครงขายผูใหบริการอืน่

ภาพที่ 1 แสดงโครงสรางของโครงขายโทรศัพทเคลื่อนที่ระบบ GSM

ภายใน BSS จะตองประกอบไปดวยอุปกรณอยางนอยดังนี้ BSC จํานวน 1 ชุด สวน PCU และ BTS ข้ึนอยูกับจํานวน Traffic ของผูใชงาน และ Config ของโครงขาย หนาที่ของอุปกรณแตละสวนมีดังนี ้

• BSC (Base Station Controller) ทําหนาที่ควบคุมการทํางานของระบบภายใน BSS

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• PCU (Package Control Unit) ทําหนาทีท่ําหนาที่ควบคุมการทาํงานของวงจรในสวนของ DATA

• BTS (Base Transceiver Station) ทําหนาที่ติดตอและรับสงสัญญาณคลื่นวทิยุกับเครื่อง MS การควบคุมการทํางานของ BTS เปนหนาทีข่อง BSC

2. BSS Functions

หนาทีห่ลักของ BSS มีดังนี ้2.1 Radio Resource Management (RRM) เปนหนาที่ของ BSC functions of the BSS. RRM is the procedure through which a stable

connection is established between the MS and the MSC for a call. This procedure is also used to release the radio resources when a call is disconnected. The limited radio resources must be dynamically allocated to maintain the stable connection between the MS and the MSC. The RRM is mainly performed by the MS and the BSC. In addition, the RRM maintains the channel connection when an MS is handed over to a neighbor cell.

Paging This describes the paging procedure. Paging is a broadcast procedure used by the

network to search for an MS. On receiving a call, the GSM/GPRS network initiates broadcasting in the location area or routing area of the paged MS. For a PS service, paging can be performed on the basis of the location area but is mainly performed on the basis of the routing area. Which area the paging is based on is determined by the SGSN.

Assignment This describes the assignment procedure. Through the assignment procedure, the BSS

assigns a TCH to an MS. Initial Access and Immediate Assignment This describes the initial access and immediate assignment procedures. The purpose of

initial access is to set up a radio resource (RR) connection on the Um interface between an MS and the network. The purpose of immediate assignment is to assign a signaling channel for setting up the RR connection.

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Authentication and Encryption This describes the authentication and encryption procedures. Authentication and

encryption are two security mechanisms used by the GSM network to enhance network security and data privacy.

System Information This describes system information (SI). The SI contains the main radio network

parameters on the Um interface. These parameters include network identification parameters, cell selection parameters, system control parameters, and network function parameters.

Handover Handover is a procedure in which a conversation can be sustained when an MS moves

from one cell to another in order to meet the requirement of network management. Radio Channel Management This describes the radio channel management procedure. Radio channel management

is performed by the BSC. It consists of long-term channel configuration management and short-term dedicated channel assignment management. The long-term management function is used to select the channel sequence number and to configure relevant devices. The short-term management function is used to assign and release various channels during communication.

Power Control This describes power control. Power control aims to reduce the transmit power of the MS

or the BTS under the condition that the radio link quality is maintained and the power level of the MS and the BSS is met. Through power control, the system interference is reduced, the frequency spectrum efficiency is improved, and the standby time of the MS is extended.

Circuit Management This describes the circuit management procedure. The BSC can manage the circuits on

the A interface. For example, it performs circuit assignment, circuit blocking, circuit unblocking, circuit group blocking, and circuit group unblocking. It also operates and maintains a single circuit or the PCM group circuits of the GEIUA/GOIUA.

TRX Management This describes the TRX management procedure. TRX management refers to TRX status

management.

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Media Access Control This describes Media Access Control (MAC). Radio Link Control This describes Radio Link Control (RLC). 2.2 Connection Management This describes the connection management of the BSS. Connection management is a

function for the control, assignment, and management of the services provided by the network. The services are short message services (SMSs), teleservices, and location-based services.

2.3 BTS Management This describes the BTS management function. BTS management is a function where procedures and messages related to the BTS are performed. The procedures and messages such as the BTS software downloading, BTS data configuration, BTS status management, and BTS alarms management should be performed by the peer-layer entities of the BSC and BTS.

2.4 BSS Operation and Maintenance This describes the OM functions of the BSS. The BSS provides OM functions, such as,

performance management, BTS OM, BSC OM, clock control setting, BSC alarms, BTS alarms, BTS commissioning, dynamic data configuration, GUI, and integrated network management interfaces. 3 Huawei BTS 3. Huawei Base Station Subsystem

BTS ของบริษัท Huawei ที่ใชงานในระบบ GSM ซึ่งบริษทัผลิตออกมาใหบริการหลายรุนดวยกันคอื BTS3012, BTS3012AE, BTS3006, BTS3006A, BTS3900, BTS3900A, DBS3900 วิธีการสังเกตดูรหัสของ BTS ในเบื้องตนนั้นสงัเกตโดยดูทีห่มายเลขรุนนั้นเลข 3 หมายถงึ BTS ระบบ GSM และตัวเลขสองหลักสุดทายจะหมายถงึจาํนวน TRX สูงสุดที่สามารถติดตั้งไดภายใน Cabinet เดียวกนั สวนตัวอักษร A หมายถงึ BTS นัน้สามารถตดิตั้งแบบ Outdoor

3.1 BTS 3012

BTS 3012 ออกแบบมาใชสําหรับใชงานแบบ macro cell ติดตั้งแบบ indoor จํานวน TRX ภายใน Cabinet ติดตั้งไดสูงสุด 12 TRXs และภายใน 1 สถานีฐาน(Site) สามารถติดตั้ง BTS 3012ไดสูงสุด 6 Cabinets ทําใหรองรับจํานวน TRX สูงสดุถึง 72 TRXs รองรับการทํางานในระบบ GSM/EDGE Radio Access Network ที่ความถี่ 850 MHz, 900 MHz, 1800 MHz, และ 1900 MHz ดังนั้น BTS 3012 จึง

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สามารถออกแบบใหรองรับไดทั้งปริมาณผูใช(Volume)และคอบคลุมพืน้ทีก่ารใหบริการ(Coverage)ไดเปนอยางดีสําหรับคุณสมบัติที่สําคัญของ BTS 3012 มีดังนี ้

• รองรับการทาํงานแบบ Power Boost Technology (PBT) ทําใหกําลงัสง TRX สูงถึง 100 w.

• ความไวของ TCH (sensitivity) ที ่-112.5 dBm (typical value in normal temperature).

• สามารถใชสัญญาณนาฬิกาไดทั้ง Line Clock และ GPSรองรับการทํางานของ Transmissions E1, FE, T1, STM-1, microwave, and satellite และ Hub transmission.

3.1.1 โครงสรางพื้นฐานของ BTS 3012

BTS3012 ประกอบดวย cabinet, antenna subsystem, OM equipment, และ auxiliary equipment ดังภาพที่ 2

ภาพที่ 2 แสดง BTS3012 Cabinet

• Cabinet เปนสวนการทาํงานหลกัของ BTS3012 โดยทําการประมาณผลทั้ง RF Signal และ Baser Band Signal

• Antenna Subsystem ทําหนาที่รับและสงสัญญาณ Uplink และ Downlink กับ MS ผานทาง Um interface

• OM Equipment เปนสวนการจัดการระบบของ BTS3012 ในระบบของ BTS3012 สามารถทํา OM ได 3 แบบดวยกนัคือ Site Maintenance Terminal, Local Maintenance Terminal และ Network iManager

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• Auxiliary Equipment เปนสวนเสริมที่ทาํใหการของระบบมีความสมบูรณ ประกอบ ดวยระบบยอยดงัตอไปนี้นี ้ Power Supply Converter. Monitor, Sensor . Report และ alarm เปนตน

3.1.1.1. Physical Structure โครงสรางทางฟสิคอลของ BTS3012 จัดไดหลายรูปแบบดวยกนั ทัง้นี้ข้ึนอยูกับ

จํานวน TRX ที่ใชงาน ซึง่ BTS3012 นั้นสามารถใชงานไดทั้ง -48 V DC และ +24 V DC สําหรับในการใชงานแบบ –48V DC นั้นระบบจะตองประกอบดวย DAFU subrack, DTRU subrack, fan subrack, common subrack, signal lightning protection subrack, transmission subrack, and power distribution unit. แสดงคอนฟกสูงสุดที่ใชไดใน 1 Cabinet คือ S4/4/4 configuration

ภาพที่ 3 แสดง Rack BTS3012

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(1) Transmission subrack (2) Common subrack (3) Fan subrack (4) DTRU subrack (5) DAFU subrack (6) Power supply unit (7) Signal lightning protection subrack

เมื่อใชงานแบบ +24 V DC นั้นระบบจะตองประกอบดวย DAFU subrack, DTRU subrack, fan subrack, common subrack, signal lightning protection subrack, transmission subrack, และ power distribution unit แสดงคอนฟกสูงสดุที่ใชไดใน 1 Cabinet คือ S4/4/4 configuration

ภาพที่ 4 แสดง Fully configured BTS3012 cabinet (+24 V DC)

(1) Power subrack (2) Common subrack (3) Fan subrack (4) DTRU subrack (5) DAFU subrack (6) Power supply unit (7) Signal lightning protection subrack

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3.1.1.2 Logical Structure

โครงสรางทาง Logical ของ BTS3012 ประกอบดวย Common Subsystem, signal protection subsystem, double-transceiver subsystem, RF front-end subsystem, power subsystem, environment monitoring subsystem, และ antenna subsystem. แสดงดังรูปที ่5

ภาพที่ 5 The logical structure of the BTS3012.

Common subsystem ติดตั้งอยูบน common subrack. ทาํหนาทีค่วบคุม clock signals ของ BTS ตรวจสอบระบบ alarms, เชื่อมตอกับโครงขายผาน Abis ประกอบดวย DTMU, DEMU, DATU, DCSU, DCCU, DPTU, DABB, and DGPS. การคอนฟกส แสดงดังภาพที่ 6

ภาพที่ 6 แสดง Commom subrack

− DTMU (Transmission/Timing/Management Unit for DTRU BTS )มีหนาที ่ 3 อยางคือ เชื่อมตอ Transmission บน Abis ควบคุม Timing

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และ Management BTSทํางานในโหมด active/standby ติดตั้งไดสูงสุด 2 บอรด

− DEMU(Environment Monitoring Unit for DTRU BTS) ทําหนาที่มอนิเตอรสัญญาณจาก Alarm Sensor ตางๆเชน smoke sensor, water sensor, temperature and humidity sensor, infrared sensor, and door control sensor และสงรายงานไปที่ DTMU สามารถคอนฟกสบน slot 2, 3, 4, หรือ 7

− DCSU(Combined cabinet Signal connection Unit for DTRU BTS) ทําหนาที่สงสญัญาณ clock signals, data signals, และ control signals จาก DTMU ไปที่ DTRU และหนาที่อีกประการหนึ่งคือเชื่อมสัญญาณระหวาง Cabinet สําหรับกรณีที Site มีการใชงานมากกวา 1 Cabinetสามารถคอนฟกสบน slot 5 เทานัน้

− DCCU(Cable Connection Unit for DTRU BTS)

− DATU(Antenna and TMA Control Unit for DTRU BTS) ทาํหนาที่ควบคุม RET antenna , Feeds power to the TMA ,Reports the RET control alarm signals และ Monitors the current from the feeder

−

ภาพที่ 7 แสดงการเชื่อมตอสัญญาณบน Common Subsystem

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− Signal Protection Subsystem ทําหนาทีป่องกนั E1 และ Signal ตางๆจากสายฟา(Lightning) ประกอบดวยโมดูล DMLC, DELC, and DSAC

3.2 BTS3012AE

This introduces the BTS3012AE. The BTS3012AE is an outdoor macro BTS that supports the double-transceiver or multi-transceiver configuration. One BTS3012AE cabinet can provide a maximum of 12 TRXs or 36 TRXs. System Architecture

The BTS3012AE system consists of the cabinet, antenna subsystem, OM equipment, and auxiliary equipment.

ภาพที่ 8 แสดงสถาปตยกรรมของ BTS3012AE

Overview

The BTS3012AE can be configured with the QTRU or the DTRU. The common features are as follows:

• Supports the TCH/FS static sensitivity of -112.5 dBm (typical value in normal temperature).

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• Supports the Hub BTS function.

• Supports soft synchronization on the Um interface.

• Supports Flex Abis networking.

• Supports optimized Abis transmission.

• Supports rapid switchover of the ring topology.

• Supports local switching.

• Supports Abis over IP.

• Supports clock over IP.

• Supports various transmission modes such as E1, FE, T1, STM-1, microwave, and satellite transmission.

Besides the above features, the BTS3012AE with the QTRU has the following features:

• Supports a maximum of 36 TRXs in a cabinet and 72 TRXs in cabinet groups.

• Supports the 900 MHz frequency band. Besides the above features, the BTS3012AE with the DTRU has the following features:

• Supports a maximum of 12 TRXs in a cabinet and 36 TRXs in multiple cabinets.

• Supports the Power Boost Technology (PBT). The maximum output power of one TRX is 100 W.

• Supports transmit diversity and four-way receive diversity.

• Supports multiple frequency bands (850 MHz, 900 MHz, 1800 MHz, and 1900 MHz) to meet requirements in different regions.

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Application Scenario

The BTS3012AE supports the evolution to the GSM/EDGE radio access network (GERAN). It is deployed in cities, rural areas, and suburbs with heavy traffic and wide coverage requirements or deployed in areas where site acquisition is difficult or the cost of an equipment room is high.

Physical Structure of the BTS3012 (for 36 TRXs)

This describes the physical structure of the BTS3012. The BTS3012 consists of the BTS3012 cabinet, antenna subsystem, and operation and maintenance (OM) equipment.

Physical Structure of the BTS3012 Cabinet

When the external -48 V DC power is used, the components of the BTS3012 cabinet are the DAFU subrack, QTRU subrack, fan subrack, common subrack, signal lightning protection subrack, transmission subrack, and power distribution unit.

ภาพที่ 9 แสดง Fully configured BTS3012 cabinet (-48 V DC)

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(1) Transmission subrack (2) Common subrack (3) Fan subrack

(4) QTRU subrack (5) DAFU subrack (6) Power distribution unit

(7) Signal lightning protection subrack

When the external +24 V DC power is used, the components of the BTS3012 cabinet are the DAFU subrack, QTRU subrack, fan subrack, common subrack, signal lightning protection subrack, power subrack, and power distribution unit.

ภาพที่ 10 แสดง Fully configured BTS3012 cabinet (+24 V DC)

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(1) Power subrack (2) Common subrack (3) Fan subrack

(4) QTRU subrack (5) DAFU subrack (6) Power distribution unit

(7) Signal lightning protection subrack

• DAFU subrack

The DAFU subrack is configured with the DDPU.

For details on the DAFU subrack, refer to BTS3012 RF Front-End Subsystem.

• QTRU subrack

The QTRU subrack can hold up to six QTRUs.

For details on the QTRU subrack, refer to BTS3012 Multi-Transceiver Subsystem.

• Fan subrack

The fan subrack is configured with one fan box that holds four fans and one fan monitoring board. The fan monitoring board detects the temperature at the air inlets at the bottom of the cabinet and automatically adjusts the fan speed.

For details on the fan subrack, refer to Fan Box.

• Common subrack

The common subrack is installed below the fan subrack. It holds the following parts:

DTMU

DEMU

DATU

DCSU

DCCU

DABB

17

DPTU

DGPS

For details on the common subrack, refer to BTS3012 Common Subsystem.

• Signal lightning protection subrack

The signal lightning protection subrack is installed on top of the cabinet. It is configured with the following boards:

DMLC

DELC

DSAC

For details on the functions of the signal lightning protection subrack, refer to Signal Protection Subsystem of the BTS3012.

• Transmission subrack

The transmission subrack is located below the common subrack. The transmission subrack reserves space for installing the baseband unit (BBU). The SDH and microwave transmission equipment can be installed in the transmission subrack.

• Power distribution unit

The power distribution unit consists of the DC lightning arrester, PGND bar, EMI filter, and the busbar at the right of the cabinet.

For details on the power distribution unit, refer to BTS3012 Power Subsystem.

• Power subrack

The power subrack is located at the bottom of the cabinet. It consists of the PSUs and the cable distribution area.

For details on the power subrack, refer to BTS3012 Power Subsystem.

18

Logical Structure

The logical structure of the BTS3012AE varies according to the external input power and the configuration of transceiver units.

• ภาพที ่11 Shows the logical structure of the BTS3012AE that uses the DC input power. In this case, the BTS3012AE consists of the following logical subsystems: common subsystem, signal protection subsystem, double-transceiver subsystem, RF front-end subsystem, power subsystem, environment monitoring subsystem, and antenna subsystem.

ภาพที่ 11 แสดง Logical structure of the BTS3012AE (DC)

• ภาพที ่ 12 Shows the logical structure of the BTS3012AE that uses the AC input power and is configured with the QTRU. In this case, the BTS3012AE consists of the following logical subsystems: common subsystem, signal protection subsystem, multi-transceiver subsystem, RF front-end subsystem, power subsystem, environment monitoring subsystem, and antenna subsystem.

19

ภาพที่ 12 Logical structure of the BTS3012AE with the QTRU (AC)

• ภาพที ่ 13 Shows the logical structure of the BTS3012AE that uses the AC input power and is configured with the DTRU. In this case, the BTS3012AE consists of the following logical subsystems: common subsystem, signal protection subsystem, double-transceiver subsystem, RF front-end subsystem, power subsystem, environment monitoring subsystem, and antenna subsystem.

ภาพที่ 13 Logical structure of the BTS3012AE with the DTRU (AC)

20

Typical Hardware Configuration

The typical hardware configuration of the BTS3012AE is categorized into the following two types:

• Typical hardware configuration of a single BTS3012AE cabinet

− When the transceiver subsystem is configured with the QTRU, refer to Typical Hardware Configuration of a Single BTS3012AE Cabinet with the QTRU for the typical hardware configuration of the BTS3012AE.

− When the transceiver subsystem is configured with the DTRU, refer to Typical Hardware Configuration of a Single BTS3012AE Cabinet with the DTRU for the typical hardware configuration of the BTS3012AE.

• Typical hardware configuration of BTS3012AE combined cabinets and cabinet groups

− When the transceiver subsystem is configured with the QTRU, refer to Typical Hardware Configuration of BTS3012AE Combined Cabinets and Cabinet Groups with the QTRU for the typical hardware configuration of the BTS3012AE.

− When the transceiver subsystem is configured with the DTRU, refer to Typical Hardware Configuration of BTS3012AE Combined Cabinets and Cabinet Groups with the DTRU for the typical hardware configuration of the BTS3012AE.

3.3 BTS 3900

BTS3900 and BTS3900A The BTS3900 is an indoor macro base station developed by Huawei. The

BTS3900 mainly consists of the BBU3900 and the RFUs. Compared with traditional BTSs, the BTS3900 features simpler structure and higher integration. The BTS3900 features:

21

• It is developed on the basis of the unified BTS platform for Huawei wireless products and enables the smooth evolution from 2G to 3G.

• It supports the Abis IP/FE interface in hardware and enables Abis over IP through software upgrade if required.

• It shares the BBU3900 subrack, which is the central processing unit, with the DBS3900 to minimize the number of spare parts and reduce the cost.

• It can be flexibly installed in a small footprint and can be easily maintained with low cost.

• It supports multiple frequency bands, such as PGSM900, EGSM900, and GSM1800.

• It supports TX diversity (not supported by the GRFU) and PBT (not supported by the GRFU).

• It supports 2-way and 4-way RX diversity (not supported by the GRFU) to improve the uplink coverage.

• It supports Frequency Domain Reflectometer (FDR) , enables accurate standing wave detection (not supported by the GRFU).

• It supports the GPRS and the EGPRS. • It supports omnidirectional cells and directional cells. • It supports the hierarchical cell, concentric cell, and micro cell. • It supports multiple topologies, such as star, tree, chain, ring, and hybrid

topologies. • It supports the A5/3, A5/2, and A5/1 encryption and decryption algorithms. • It supports the cell broadcast SMS and point-to-point SMS. • It supports coexistence with the BTS3X, BTS3012, and DBS3900. • When the DRFU is configured for the BTS3900, a BTS3900 can support a

maximum of 12 carriers in the maximum cell configuration of S4/4/4. In addition, a site configured with the BTS3900s can support a maximum of 36 carriers in the maximum cell configuration of S12/12/12.

• When the GRFU is configured for the BTS3900, a BTS3900 can support a maximum of 36 carriers in the maximum cell configuration of S12/12/12. In

22

addition, a site configured with the BTS3900s can support a maximum of 72 carriers in the maximum cell configuration of S24/24/24.

• Supports smooth evolution from 2G to 3G through the unified BTS platform. • Supports multiple frequency bands, such as PGSM900, EGSM900, and

DCS1800. • Supports transmit diversity and PBT. • Supports two-way and four-way receive diversities to improve the uplink

coverage. • Supports the GPRS and EGPRS. • Supports multiple network topologies, such as star, tree, chain, ring, and hybrid

topologies. • Supports the cell broadcast SMS and point-to-point SMS.

System Architecture

The BTS3900 GSM system consists of the cabinet, antenna subsystem, OM equipment, and auxiliary equipment. ภาพที่ Shows the BTS3900 GSM system architecture.

ภาพที่ 14 BTS3900 GSM system architecture

23

System Architecture of the BTS3900

The BTS3900 consists of the BBU3900, RFUs, and indoor macro cabinet. The BBU3900 and RFUs are installed in the indoor macro cabinet.

ภาพที่ 15 แสดง BTS3900 system

The BTS3900 mainly consists of the following components:

• The BBU3900 is used for baseband processing and enables interaction between the BTS and the BSC.

• The RFU is an RF filtering unit, which performs modulation, demodulation, data processing, and combining and dividing for baseband signals and RF signals.

• The indoor macro cabinet houses the BBU3900 and RFUs. In addition, the indoor macro cabinet provides the functions such as power distribution, heat dissipation, and surge protection

• The RFUs are of two types: DRFUs and GRFUs.

24

Logical Structure of the BTS3900

The BTS3900 mainly consists of the BBU and RFUs. The logical structure of the BTS3900 consists of the RF subsystem, control subsystem, power subsystem, and antenna subsystem.

ภาพที่ 16 แสดง Logical structure of the BTS3900

The logical subsystems of the BTS3900 are as follows:

• RF subsystem, implemented by the DRFU or GRFU

• Control subsystem whose functions are implemented by the BBU

• Power subsystem whose functions are implemented by the following modules:

DCDU-01 Module in the BTS3900 cabinet (-48 V DC)

DCDU-01 Module and Power Subrack (DC/DC) in the BTS3900 cabinet (+24 V DC)

25

DCDU-01 Module and Power Subrack (AC/DC) in the BTS3900 cabinet (220 V AC)

• Antenna subsystem whose functions are implemented by the following modules:

GATM

TMA

Antenna

Structure of the BTS3900 -48 V Cabinet

The BTS3900 cabinet (-48 V) uses the external -48 V DC input. The DC power is directly led into the DCDU-01 and the DCDU-01 distributes the DC power to each component in the cabinet. The BTS3900 -48 V cabinet can be installed alone, stacked on another BTS3900 -48 V cabinet, or installed side by side with another BTS3900 -48 V cabinet.

The BTS3900 -48 V cabinet consists of the following components: the DRFUs or GRFUs, BBU, GATM, DCDU-01, and FAN unit, among which the GATM is optional.

Single Cabinet Installation

ภาพที่ 17 แสดง Typical configuration of the BTS3900 -48 V cabinet in single cabinet installation

26

Double Cabinet Installation

ภาพที่ 18 แสดง Typical configuration of two BTS3900 -48 V cabinets in side-by-side installation

ภาพที่ 19 แสดง Typical configuration of two BTS3900 -48 V cabinets in stack

27

BTS3900/BTS3900A Configuration Principles

The BTS3900/BTS3900A is configured with RFUs. When the DRFU is configured, a single BTS3900/BTS3900A provides a maximum of 12 carriers with the maximum cell configuration of S4/4/4. When the GRFU is configured, a single BTS3900/BTS3900A provides a maximum of 36 carriers with the maximum cell configuration of S12/12/12. The BTS3900/BTS3900A is configured with the antenna system, RFUs, and BBU.

Basic Configuration Principles

• If multiple hardware configurations meet the requirements for the RNP parameter settings, the configuration mode that supports smooth upgrades is preferred.

• The DRFU supports a maximum of two carriers and it is applicable to small- and middle-capacity scenarios; the GRFU supports a maximum of six carriers and it is applicable to large-capacity scenarios. The DRFU and GRFU can be configured in the same cabinet or cell to support flexible capacity expansion.

• Wide coverage is preferred. The DRFU supports the PBT, TX diversity, and 4-way RX diversity mode. Therefore, the DRFU can be applied to wide-coverage scenarios.

Antenna Configuration Principles

• One dual-polarized antenna can serve a maximum of two RFUs.

• By default, RX diversity is adopted on the GSM network. That is, two feeders connected to two single-polarized antennas or one dual-polarized antenna must be configured in a cell.

• Each sector of the BTS must be configured with the minimum number of antennas.

• For the 2-way RX diversity, each sector has two antenna channels; for the 4-way RX diversity, each sector has four antenna channels.

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RF Configuration Principles

Table 1 describes the RF configuration principles of the BTS3900.

Table 1 RF configuration principles of the BTS3900

Principle Description Example

Configuration principles of the DRFU ports

• ANT1 and ANT2 are the TX ports of the duplexer. They are connected to jumpers.

• Rx1 in, Rx1 out, Rx2 in, and Rx2 out are the ports for signals between interconnected DRFUs. When two carriers provided by a DRFU belong to the same cell, both Rx1 in and Rx2 in can be the input ports for RX diversity of the two carriers. When two carriers provided by a DRFU belong to different cells, Rx1 in is the input port for RX diversity of carrier 1; Rx2 in is the input port for RX diversity of carrier 2.

• CPRI_0 and CPRI_1 are the ports for high-speed electrical cables. The CPRI_1 port is connected to the CPRI port on the BBU or to the upper-level RFU in the case of cascaded RFUs. The CPRI_0 port is connected to the lower-level RFU

In S3/3 configuration, three DRFUs need to be configured. The carriers provided by the middle DRFU belong to different cells. That is, the Rx1 in port on the middle DRFU is the input port for RX diversity of carrier 1, which belongs to the first cell. The input port for RX main of carrier 1 is ANT1. The Rx2 in port is the input port for RX diversity of carrier 2, which belongs to the second cell. The input port for RX main of carrier 2 is ANT2.

29



in the case of cascaded RFUs.

Configuration principles of the GRFU ports

• The ANT_TX/RXA port supports signal reception and transmission, and the ANT_RXB port supports signal reception. They are connected to jumpers.

• RX_INB and RX_OUTA are the ports for signals between interconnected GRFUs.

• CPRI_0 and CPRI_1 are the ports for high-speed electrical cables. The CPRI_0 port is connected to the CPRI port on the BBU or to the upper-level RFU in the case of cascaded RFUs. The CPRI_1 port is connected to the lower-level RFU in the case of cascaded RFUs.

None.

Configuration principles of a single cabinet

• Star topology is adopted between the BBU and RFUs. The RFUs and the high-speed CPRI ports on the BBU have a one-to-one relationship. That is, if slot 1 on the RFU is idle, CPRI port 1 on the BBU is also idle.

• When the DRFU is configured,

None.

30



the maximum cell configuration of a single cabinet is S4/4/4. When the GRFU is configured, the maximum cell configuration of a single cabinet is S12/12/12.

Configuration principles of multiple cabinets

When star and chain topology is adopted between the BBU and RFUs, the RFU supports 3 levels of cascading in a chain and thus the BBU supports a maximum of 18 (6 x 3) RFUs.

None.

Two TRXs of one DRFU configured in one sector

• A single DRFU does not support the S1/1 application; however, three DRFUs support the S3/3 application.

• When the DRFU works in TX PBT, TX diversity, or 4-way RX diversity mode, a DRFU provides only one TRX. Therefore, you can configure the DRFU as required.

For example, for a site in S5/4/7 cell configuration, nine DRFUs are installed to meet the requirements of S6/4/8 cell configuration, but data configuration is still performed on the basis of the S5/4/7 cell configuration.

Number of DRFUs

• When the number of TRXs of the site is less than 12, an odd number of TRXs can be configured for a cell. Number of DRFUs = round up [(number of

• S3/3/3: Number of DRFUs = round up (9 / 2) = 5; S1/2/3: Number of DRFUs = round up [(6 + 1) / 2] = 4.

• After two TRXs are configured

31



TRXs + number of S1 cells) / 2] • When the number of TRXs of

the site is greater than 12, an even number of TRXs should be configured for a cell. Number of DRFUs = round up (number of TRXs after two TRXs are configured in one sector / 2)

in one sector, the S5/5/5 configuration is S6/6/6. Number of DRFUs = (6 + 6 + 6) / 2 = 9.

Number of GRFUs

• One GRFU does not server two cells. Each cell with a single antenna can be configured with a maximum of two GRFUs.

• One GRFU supports a maximum cell configuration of S6; two GRFUs supports a maximum cell configuration of S12. To support the configuration larger than S12, multiple antenna systems are used.

None.

DRFU TRX allocation in double-antenna-system mode

After TRX allocation, the cells with an odd number of TRXs become neighboring cells of each other. • S5 = S3 + S2 or S5 = S2 + S3 • S6 = S4 + S2 or S6 = S3 + S3 • S7 = S4 + S3 or S7 = S3 + S4

• In S3/5/4 configuration, S5 can be divided into S3 + S2. Then, the cell configuration becomes S3/(3/2)/4.

• In S2/5/5 configuration, the first S5 is divided into S2 + S3; the second S5 is divided into S3

32



• S8 = S4 + S4 + S2. Then, the cell configuration becomes S2/(2/3)/(3/2).

DRFUs at two bands configured in a site

• If the number of DRFUs is not more than 6 in a double-band site, the DRFUs at two bands are configured in the same cabinet. If the RF cabinet is configured with less than three 900 MHz DRFUs and three 1800 MHz DRFUs, the 900 MHz DRFUs are installed in of the three slots on the left of the RF cabinet, and the 1800 MHz DRFUs are installed in the three slots on the right of the RF cabinet.

• When two RF cabinets are configured and the number of DRFUs at each band is not more than six, the 900 MHz DRFUs are installed in the first RF cabinet and the 1800 MHz DRFUs are installed in the second RF cabinet. The DRFUs are installed in the slots according to the typical S4/4/4 configuration.

None.

33



When two RF cabinets are configured and the number of DRFUs at one band (for example, 900 MHz) is greater than six, other DRFUs at this band share the other RF cabinet with the DRFUs at the other band (for example, 1800 MHz). The mixed configuration of DRFUs at two bands is not allowed.

Coexistence configuration principles of the DRFUs and GRFUs

Coexistence configuration principles of the DRFUs and GRFUs are as follows: • The primary BCCH is carried

on a GRFU. • When the requirements of the

output power and number of carriers are met and the cell configuration is greater than S4, a single DRFU is configured with one TRX; when two DRFUs are configured, one DRFU is preferably used.

• The TX power of a DRFU and that of a GRFU within a cell are almost the same. The power

None.

34



difference should not exceed 0.5 dB.

• When the DRFUs and GRFUs are configured in one cell, 4-way RX diversity and TX diversity are not supported.

• The DRFUs and GRFUs are not recommended in the same new site.

BBU Configuration Principles

• A BBU has 6 CPRI ports and supports a maximum of 72 carriers.

• Shows the BBU slots.

ภาพที่ 20 แสดง BBU slots

35

• Table 2 describes the board configuration principles of the BBU.

Table 2 Board configuration principles of the BBU

Module or Board

Description

UBFA One UBFA must be configured.

UPEU One UPEU must be configured. A second UPEU can be configured when the backup power is

required. The BBU, however, cannot be configured with the UPEU and the UEIU at the same time.

UEIU One UEIU must be configured when more than two BTS3900 cabinets are configured in a single site.

In the outdoor application, one UEIU must be configured when more than one APM30 power cabinet is configured.

GTMU One GTMU must be configured. The GTMU is installed in slot 5 or slot 6.

UELP Not required in the BTS3900 One UELP must be configured in the BTS3900A. The UELP is

installed in slot 1.

USCU The USCU is optional and a maximum of one USCU can be configured.

The USCU is installed in slot 0.

36

CPRI Cable Connections of the RFUs

The RFUs support various topologies: star, chain, and ring.

ภาพที่ 21 แสดง Typical topology of the DRFUs

ภาพที่ 22 แสดง Typical topology of the GRFUs

37

Table 3 describes the three typical topologies of the DRFUs.

Table 3 Three typical topologies of the DRFUs

Topology Application Scenario

Star Supports the minimum configuration scenarios

Chain Supports the maximum configuration scenarios

Ring Supports the high reliability scenarios

3.4 BTS3900A GSM

This introduces the BTS3900A GSM. The BTS3900A GSM is the fourth-generation outdoor macro BTS developed by Huawei.

System Architecture

The BTS3900A GSM system consists of the cabinet, antenna subsystem, OM equipment, and auxiliary equipment

ภาพที่ 23 แสดง BTS3900A GSM system architecture

38

Overview

The features of the BTS3900A GSM are as follows:

• Supports smooth evolution from 2G to 3G through the unified BTS platform.

• Supports the Abis IP/FE port in hardware and supports Abis over IP through software upgrade.

• Shares the BBU, which is the central processing unit, with the DBS3900 GSM to minimize the number of spare parts and reduce the cost.

• Features small size, flexible installation, easy maintenance, and low OM cost.

• Supports multiple frequency bands, such as PGSM900, EGSM900, and DCS1800.

• Supports transmit diversity and PBT.

• Supports two-way and four-way receive diversities to improve the uplink coverage.

• Supports the GPRS and EGPRS.

• Supports omnidirectional cells and directional cells.

• Supports the hierarchical cell, concentric cell, and micro cell.

• Supports multiple network topologies, such as star, tree, chain, ring, and hybrid topologies.

• Supports the A5/3, A5/2, and A5/1 encryption and decryption algorithms.

• Supports the cell broadcast SMS and point-to-point SMS.

• Supports synchronization with the BTS3012.

• Supports a maximum of 12 TRXs in a cabinet and the maximum configuration of S4/4/4.

39

• Supports a maximum of 72 TRXs in multiple cabinets and the maximum configuration of S24/24/24.


A single BTS3900A GSM cabinet supports the S4/4/4 configuration. The BTS3900 GSM can support the S4/4/4 + S4/4/4 configuration through cabinet stack. When the equipment room space is limited, the large-capacity configuration can be used to realize the coverage of densely populated urban areas.

Structure of the BTS3900A Cabinet

The BTS3900A cabinet consists of the RF cabinet and the APM30 power cabinet. The RF cabinet is categorized into two types, namely 3RFU cabinet and 6RFU cabinet. The APM30 battery cabinet and APM30 transmission cabinet, which provide backup power for a long period of time and space for user equipment respectively, are optional for the BTS3900A.

The function modules of the BTS3900A include the DRFU, BBU, DCDU-02, FMUA, FAN unit, and GATM, among which the GATM is optional.

40

ภาพที่ 24 แสดง Typical configuration of a BTS3900A cabinet (1) (1) 6RFU cabinet (2) DRFU (3) FAN unit

(4) FMUA (5) DCDU-02 (6) GATM

(7) BBU (8) PDU (9) Power subrack (AC/DC)

(10) APM30 power cabinet - -

41

ภาพที่ 25 แสดง Typical configuration of a BTS3900A cabinet (2) (1) Battery (2) 3RFU cabinet (3) DRFU

(4) FAN unit (5) FMUA (6) DCDU-02

(7) GATM (8) BBU (9) PDU

(10) Power subrack (AC/DC) (11) APM30 power cabinet -

42




(10) APM30 power cabinet (11) Battery (12) 3RFU cabinet

43




(10) APM30 power cabinet (11) DCDU-03A (12) Transmission unit

(13) APM30 transmission cabinet (14) Battery (15) APM30 battery cabinet

44

Logical Structure

The BTS3900A GSM consists of the BBU and DRFU. The BTS3900A GSM consists of the following logical subsystems: RF subsystem, control subsystem, power subsystem, and antenna subsystem. Figure 2 shows the logical structure of the BTS3900A GSM.

ภาพที่ 28 แสดง Logical structure of the BTS3900A GSM

Typical Configuration of the BTS3900/BTS3900A

This lists the number of components required for the cell configuration of S1/1/1, S2/2/2, S4/4/4, S6/6/6, S1/1/1 + S3/3/3, S2/2/2 + S2/2/2, and S4/4/4 + S4/4/4.

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Table 4 lists the typical configuration of the BTS3900/BTS3900A.

Table 4 Typical configuration of the BTS3900/BTS3900A

Typical Configuration

Number of DRFUs

Number of Antennas

Number of Other Components of the

BTS3900


BTS3900A

S1/1/1 3 3 • BTS3900 cabinet: 1

• FAN unit: 1 • DCDU-01: 1 • BBU: 1 • Power subrack

(DC/DC): 1 (+24 V DC input)

• Power subrack (AC/DC): 1 (220 V AC input)

• GATM: optional

• APM30 power cabinet: 1

• Power subrack (AC/DC): 1

• PDU: 1 • BBU: 1 • GATM: optional • RF cabinet: 1 • FMUA: 1 • DCDU-02: 2 • FAN unit: 2

S2/2/2 3 3

S4/4/4 6 3

S2/2/2 + S2/2/2

6 6

S6/6/6 9 6 • BTS3900 cabinet: 2

• FAN unit: 2 • DCDU-01: 2 • BBU: 1 • Power subrack

(DC/DC): 1 (+24 V DC input)

• Power subrack (AC/DC): 1 (220 V AC

• APM30 power cabinet: 1

• Power subrack (AC/DC): 1

• PDU: 1 • BBU: 1 • GATM: optional • RF cabinet: 2 • FMUA: 2 • DCDU-02: 4

S1/1/1 + S3/3/3

8 6

S4/4/4 + S4/4/4

12 6

46

Table 4 Typical configuration of the BTS3900/BTS3900A

Typical Configuration

Number of DRFUs

Number of Antennas


BTS3900


BTS3900A

input) • GATM: optional

• FAN unit: 4

3.5 DBS 3900 Introduction to the DBS3900 GSM

This introduces the DBS3900 GSM. The DBS3900 GSM is a type of multi-transceiver distributed base station developed by Huawei.

System Architecture

The DBS3900 GSM consists of the BBU3900 GSM, RRU3004, and antenna subsystem.

ภาพที่ 29 แสดง DBS3900 GSM system architecture

47

• The BBU3900 GSM provides physical interfaces for connections with the BSC and RRU. It performs centralized management (OM and signaling processing) of the entire base station system and provides the reference clock to the system.

• The RRU3004 is an outdoor remote RF unit. It processes baseband signals and RF signals.

• The antenna subsystem receives uplink signals and transmits downlink signals on the Um interface.

Overview

The DBS3900 GSM has the following features:

• The maximum remote distance in cascaded mode is 40 km.

• Each RRU module carries two TRXs. The two combined RRU modules carry four TRXs.

• Each BBU supports a maximum of 36 TRXs. It can support Abis IP through software upgrade.

• Supports the Power Boost Technology (PBT). The maximum output power of the TRX is 40 W at 900 MHz or 30 W at 1800 MHz.

• Supports the TCH/FS static sensitivity of -112.5 dBm (typical value in normal temperature).

• Supports transmit diversity and four-way receive diversity.

• Supports software synchronization

• Supports E1 and T1 transmission

• Supports multiple network topologies, such as star, tree, chain, ring, and hybrid topologies.

• Supports Flex Abis networking.

• Supports transmission sharing between the GSM system and the UMTS system.

48

• Supports AMR.

• Supports Abis transmission optimization. It supports the detection and recovery of idle frames on the DBS and the BSC sides. Idle frames are not transmitted on the transmission link. This saves the transmission bandwidth.

• Supports multiple frequency bands (850 MHz and 1800 MHz) to meet requirements in different regions.


The DBS3900 GSM uses the Remote Radio Head (RRH) technology and features flexible topology. It can be deployed in indoor coverage scenarios and outdoor coverage scenarios, such as city street, highway, and railway.

BBU3900 GSM Module

Each BBU3900 GSM consists of five logical units: BTS interface unit, central processing unit, high-speed interface unit, clock unit, and monitoring unit.

ภาพที่ 29 แสดง Logical structure of the BBU3900 GSM

49

For details on the logical units of the BBU3900 GSM, refer to:

• BTS Interface Unit

• Central Processing Unit

• High-Speed Interface Unit

• Clock Unit

• Monitoring Unit

RRU3004 Module

Each RRU3004 module consists of five logical units: high-speed interface unit, signal processing unit, power amplifier (PA), dual duplexer, and low noise amplifier (LNA).

ภาพที่ 30 แสดง Logical structure of the RRU3004

For details on the logical units of the RRU3004, refer to:

• High-Speed Interface Unit

• Signal Processing Unit

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• PA

• Dual Duplexer

• LNA

3.6 BSC

BSC Physical Structure

This describes the physical structure of the BSC, including the cabinet, cables, LMT computers, and alarm box.

ภาพที่ 31 แสดง Physical structure of the BSC

LMT: Local Maintenance Terminal PDF: Power Distribution Frame

Table 5 lists the components of the BSC.

Table 5 Components of the BSC

Component Introduction Description

GSM BSC control processing rack (GBCR)

The GBCR provides switching and processes

For details, refer to GBCR (Configuration Type A) and GBCR

51



services for the BSC. One GBCR is configured in a BSC.

(Configuration Type B).

GSM BSC service processing rack (GBCR)

The GBSR processes various services for the BSC. The number of GBSRs to be configured depends on the traffic volume. Zero to three GBSRs can be configured.

For details, refer to GBSR Cabinet.

BSC Cables BSC cables are classified into the Ethernet cable, optical cable, and trunk cable. The number of BSC cables to be configured depends on actual requirements.

For details, refer to BSC Cables.

BSC LMT The LMT is a computer that is installed with the LMT software package and is connected to the OM network of the NEs. It is optional for the BSC.

For details, refer to LMT-Related Definitions.

Alarm box The alarm box can generate audible and

User manual delivered with the alarm box

52



visual alarms. It is mandatory for the BSC.

BSC Logical Structure

Logically, the BSC system consists of the TDM switching subsystem, GE switching subsystem, service processing subsystem, service control subsystem, interface processing subsystem, clock subsystem, power subsystem, and environment monitoring subsystem.

ภาพที่ 32 แสดง Logical structure of the BSC

The interface processing subsystem of the BSC provides the Pb or Gb interface, depending on the types of PCU.

53

• When the built-in PCU is used, the interface processing subsystem provides the Gb interface to enable the communication between the BSC and the SGSN.

• When the external PCU is used, the interface processing subsystem provides the Pb interface to enable the communication between the BSC and the PCU.

The interface processing subsystem of the BSC cannot provide the Gb interface and Pb interface simultaneously.

The interface processing subsystem supports different transmission modes over the A interface:

• When the IP transmission is used, the A interface enables the communication between the BSC and the MGW.

• When the TDM transmission is used, the A interface enables the communication between the BSC and the MSC/MGW.

The interface processing subsystem of the BSC cannot support the two transmission modes simultaneously.

BSC Hardware Configuration

This describes three types of BSC subracks, two installation modes of the GTCS, three combination modes of BSC subracks, two types of PCU, and two types of hardware configuration.

BSC Subracks

The BSC subracks can be classified into the following types:

• GMPS

• GEPS

• GTCS

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Generally, both the GMPS and GEPS are referred to as the BM subrack, and the GTCS is referred to as the TC subrack.

Both the BM subracks and the TC subracks have two interconnection modes.

• Inter-Subrack TDM Interconnections

The inter-subrack TDM interconnections between one BM subrack and another BM subrack and between one TC subrack and another TC subrack are established through the inter-GTNU cables. For details, refer to Physical Structure of the BSC TDM Switching Subsystem.

• Inter-Subrack GE Interconnections

The GSCUs in the BM subracks or in the TC subracks are connected in star topology. The subrack located in the center of the star topology is referred to as the main subrack, and the subracks connected to the main subrack are referred to as extension subracks. For the inter-subrack GE interconnection of BM subracks, the GMPS must be the main subrack, and the GEPS must be the extension subrack. For the inter-subrack GE interconnection of TC subracks, any TC subrack can be the main subrack, and the other TC subracks must be extension subracks. For details, refer to Physical Structure of the BSC GE Switching Subsystem.

Installation Modes of the GTCS

The GTCS can be configured on the BSC side and on the MSC side. If the GTCS is installed on the BSC side, the installation mode is referred to as local GTCS. If the GTCS is installed on the MSC side, the installation mode is referred to as remote GTCS.

• In local GTCS mode, the GSCU in the main GTCS is connected to the GSCU in the GMPS through the crossover cable. In remote GTCS mode, the GTCS is installed in an independent GBSR and does not share a cabinet with the GMPS/GEPS. In addition, the

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GSCU in the main GTCS is not connected to the GSCU in the GMPS.

ภาพที่ 33 แสดง OM path between the GMPS and the main GTCS (in local GTCS mode)

ภาพที่ 34 แสดง OM path between the GMPS and the main GTCS (in remote GTCS mode)

As shown in Figure 33 when OM is performed on the local GTCS, the OM information is carried by the GE link between the GSCU in the GMPS and the GSCU in the main GTCS. The transmission rate is fast.

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As shown in Figure 34 when OM is performed on the remote GTCS, the OM information is carried by the E1/T1 link between the GEIUT/GOIUT in the GMPS and the GEIUT/GOIUT in the main GTCS. The transmission rate is slow.

The application scenarios of the local GTCS and remote GTCS are as follows: If the distance between the GSCU in the GMPS and the GSCU in the main GTCS exceeds the maximum length of a crossover cable, the remote GTCS should be configured. Otherwise, the local GTCS should be configured. For example, the crossover cable can be made on site and its maximum length is 100 m. If the distance between the GMPS and the main GTCS exceeds 100 m, the remote GTCS should be configured. Otherwise, the local GTCS should be configured.

Configuration Modes of BSC Subracks

The BSC subracks support the following configuration modes:

• BM/TC separated

In BM/TC separated configuration mode, the BSC consists of the GMPS/GEPS and GTCS. The GTCS can be configured on the BSC side or on the MSC side.

Characteristics: In this configuration mode, the GTCS can be configured flexibly. The GTCS can be configured in an independent GBSR on the MSC side, thus saving the transmission resources between the BSC and the MSC. The GTCS can be configured on the BSC side and share a cabinet with other subracks.

• BM/TC combined

In BM/TC combined configuration mode, the TC function is performed by the GMPS or GEPS. When the TC is configured in the GMPS, the subrack is still referred to as the GMPS. When the TC is configured in the GEPS, the subrack is still referred to

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as the GEPS. In BM/TC combined configuration mode, the TC function is performed by the GDPUX.

Characteristics: Compared with the BM/TC separated configuration mode, the BSC in BM/TC combined configuration mode has a high density of integration. In addition, when the capacity is the same, the BSC in BM/TC combined configuration mode has fewer cabinets and subracks.

• A over IP

In A over IP configuration mode, the BSC consists of the GMPS/GEPS and is not configured with the GTCS. In this case, layer 3 of the A interface protocol stack uses IP, and the TC function is performed by the MGW. Thus, the GTCS is not required.

Characteristics: In A over IP configuration mode, the BSC has few cabinets and subracks. In this case, the BSC must be connected to the Huawei MGW.

Types of PCU

The BSC supports two types of PCU: built-in PCU and external PCU.

• The external PCU is an independent network element that provides PS service processing functions. It communicates with the BSC over the Pb interface, and communicates with the SGSN over the Gb interface.

Characteristics: The external PCU requires a large floor area and is difficult for installation and maintenance.

• The built-in PCU is the GDPUP, which provides PS service processing functions. The GDPUP is configured in the GMPS/GEPS.

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Application scenario: Compared with the external PCU, the built-in PCU is a board that can be installed in a BSC subrack. The built-in PCU features small footprint, easy cabling, and convenient installation and maintenance.

The requirements for the configuration of the PCU vary with the transmission modes over the Abis interface.

• When the IP protocol is used on layer 3 or HDLC protocol is used on layer 2 of the protocol stack on the Abis interface, the BSC must use the built-in PCU.

• When TDM transmission is used over the Abis interface, the BSC can use either the built-in PCU or the external PCU.

BSC Hardware Configuration Types

The BSC supports two types of server: GBAM and GOMU. The GBAM/GOMU enables the communication between the Local Maintenance Terminal and the BSC.

• The GBAM is independent from the BSC components. It is connected to the GSCU in the GMPS through the FE/GE port. If the GBAM is used, it is configured in subrack 0 of the GBCR.

Characteristics: If the GBAM is used, the KVM must be configured to serve as the operating platform for the GBAM. The GBAM occupies a subrack in the GBCR and the cable connection of the GBAM is complex.

• The GOMU is a type of board in the BSC. One GOMU occupies two slots. The GOMU should be installed in slots 00 to 03 or slots 20 to 23 in the GMPS.

Characteristics: Compared with the GBAM, the GOMU requires a small installation space. In addition, the GOMU features simple cable connection and easy installation and maintenance.

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The BSC hardware configuration is classified into configuration type A and configuration type B based on the server used.

• In configuration type A, the BSC is configured with the GBAM.

• In configuration type B, the BSC is configured with the GOMU. Compared with configuration type A, the BSC in configuration type B can save a subrack. In addition, the cable connection is simple and the installation and maintenance is easy.

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GSM Base Station Subsystem