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BSS overviewBSS overview

BSS S11

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BSS overviewBSS overview

Following this module you will be able to:

• Name the GSM subsystems and their functions• Name the BSS network elements and their functions• Name the BSS interfaces

Refer to S11 Documentation:

• Descriptions\SystemDescriptions\NokiaBase Station SubsystemDescription\Overview to Nokia Base Station Subsystem

• Descriptions\System Descriptions\NokiaBase Station SubsystemDescription\GSM network architecture

Refer to S11 Documentation:

• Descriptions\System Descriptions\NokiaBase Station Subsystem Description\ Overviewto Nokia Base StationSubsystem

• Descriptions\System Descriptions\NokiaBase Station Subsystem Description\ GSMnetwork architecture

Further refer to:

• Descriptions\System Descriptions\NokiaBase Station Subsystem Description\ . . .

• Nokia Talk Family Customer Documentation: Product Description

• Nokia UltraSiteEdge Customer Documentation

• Nokia Talk InSiteCustomer Documentation

• Nokia Talk MetroSiteCustomer Documentation

• Nokia PrimeSiteCustomer Documentation

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GSM subsystemsGSM subsystems

NSS BSS

Control flow

Userdata flowPSTN

PLMN

PSPDN

CSPDN

ISDN

PSTN Public Switched TelephoneNetwork

PSPDN Packet SwitchedPublicData Network

PLMN Public Land MobileNetwork

CSPDN Circuit-SwitchedPublicData Network

ISDN IntegratedServices Digital Network

OSS

Refer to S11 Documentation:

• Descriptions\ System Descriptions\ NokiaBase Station SubsystemDescription\ GSMnetwork architecture

 The GSM network is divided into three subsystems: Network Switching Subsystem, Base StationSubsystem and Network Management System.

 The main task of theBase Station Subsystem(BSS) is to connect the mobile user to the NetworkSwitching Subsystem through a radio interface. It controls the cellular radio interface and thetransmission links between the elements of the BSS.

 TheNetwork Switching Subsystem(NSS) is responsible for setting up connections between mobile usersand other telecommunication users. It manages the set-up, charging, and security aspects of the call.

 TheOperations Support System(OSS) is used to manage the GSM/DCS network, gathering alarms and

statistics on the network’s performance. It is also used to control the network by remote commands sentinto the Network Elements.

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BSS Network ElementsBSS Network Elements

OSS

MSC

BTS

BTS

BTS

BSC

MS

BSS

SGSN

TCSM2

Transcoder, TCSM2- considered as part of the BSC- normally at the MSC site- used for converting the bit rate of traffic

channels between 64 and 16kbit/s- speech activity detection- framing and synchronisation of the vocoder

block- interfaces to the MSC / BSC

Base Station Controller, BSC- terrestrial channel management- configuration and management of traffic channels- frequency hopping control

- paging- BTS and MS power control- idle channel quality monitor- quality and field strength control for active channels- handover control- maintenance of BTS / BSC / TC- interfaces to the NMS / BTS / TC / SGSN

Base Transceiver Station, BTS- timing Broadcast Control Channels (BCCH) and Common Control Channels (CCCH)- forwarding MS and BTS measurements to the BSC- detecting RACHs(Random Access Channels) from the MS- channel coding and decoding on the radio path- interleaving and deinterleavingon the radio path- encryption and decryption on the radio path- performing frequency hopping- GMSK modulation, demodulation, up / down conversion and power amplifying- transmitter RF signal combining- receiver RF signal filtering, amplifying and multicoupling- reporting idle traffic channel quality to the BSC

Transmission Unit TRU- providesAbis interface- reallocates the Traffic and signalling channels in the BTS

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BSS interfacesBSS interfaces

MSC

SGSN

ET

ET

ET

ET

ET ET

A IF Ater IF Abis IF Air IF

Gb IF

ET

ET

ET

ET

TCSM2E

MS

BTS

 TRU

BSC

ET

ET

ET

Refer to S11 Documentation:

• Plan\Network Element\Engineering for BSC\The BSC in the GSM Network

• Plan\Network Element\Engineering for BSC3i\The BSC in the GSM Network\Introducingthe BSC3i\Overviewof the BSC3 in GSM/EDGE mobilenetwork

A interface: - between MSC and TCSM

- 2 Mbit/s interface (G.703)

Ater interface: - between TCSM and BSC

- 2 Mbit/s interface (G.703)

Abisinterface: - between BSC and BTS

- 2 Mbit/s interface (G.703)

- structure depends on the connection type and signalling (64kbit/s,32kbit/s or 16kbit/s) used

Air interface: - between BTS and MS

- TDMA frame for sending signals intended for various users on thesame radio frequency in different time slots.

X.25: - between MSC / BSC and OMC

- two ways to implement: analogue X.25 and digital X.25

Gbinterface: - between SGSN and BSC

- Frame Relay Protocol on 2 Mbit/s interface (G.703)

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Exercise: Network Elements and interfacesExercise: Network Elements and interfaces

OMC

MSC

MS

BSS

SGSN

Exercise: Network Elements and interfaces (duration ~10 minutes)

Label this diagram with the names of the individual elements, and indicate the

connecting interfaces.