03 RA22123EN09GLS0 Bsc Architecture

BSC architecture

RA22123EN09GLS0 2008 Nokia Siemens Networks

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Contents 1 Functions 3 1.1 Traffic channel switching 5 1.2 Signaling information processing 7 2 Modules 11 2.1 Switching network 14 2.2 Peripheral processors 16 2.3 Telephony processor 19 2.4 Administrative processor 19 2.5 Line termination 19 2.6 Hard disk 19 2.7 CPEX / ESAM 19 2.8 O&M interface IXLT 19 2.9 Clock unit 19 2.10 Packet control unit 19 2.11 Bus systems 19 3 BSC Connections 19 3.1 Local Maintenance Terminal 19 3.2 Operation and Maintenance Link 19 3.3 Gb interface 19 3.4 High speed Gb Interface 19 4 Rack configuration 19 4.1 Module combinations 19 4.2 Rack layout 19 4.3 Redundancy concept 19 4.4 Power supply 19 5 Exercises 19

BSC architecture

BSC architecture


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BSC architecture


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1 Functions

BSC architecture


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The Base Station Controller BSC is the "brain" of the Siemens Base Station SBS. The BSC is responsible for

Traffic channel switching, Signaling information processing, (Central) Operation & Maintenance handling and alarm monitoring. The BSC features interfaces to carry payload (and signaling) to

Base Transceiver Station Equipment BTSE, Transcoder and Rate Adapter Unit TRAU, Mobile Switching Center MSC, Serving GPRS Support Node SGSN as well as interfaces to provide Operation and Maintenance from

Operation and Maintenance System RC, Local Maintenance Terminal LMT. Note: With the LMT connected to BSC (local or remote), all network elements controlled from this BSC (all BTSE and TRAU) may be administered.

BTSE

LinkInterface

SN LinkInterface

BSCControl

LMTOMC

BSC

SGSN

BTSE TRAU

PCU

LinkInterface

BTSE

Fig. 1 BSC architecture

BSC architecture


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1.1 Traffic channel switching The BSC switches

circuit-switched traffic (e.g. voice) coming from the MSC via the TRAU and packet-s1w0itched traffic (e.g. GPRS data) coming from the SGSN Both PCM30 and PCM24 lines are supported (by the same link interface modules).

BTSE

BTSE

TRAULinkInterfaceLink

Interface

SN-1BSC

SGSNLink

InterfaceLink

Interface

.

.

.

.

.

.

SN-0

Abisvia PCMB

Asubvia PCMS

Gbvia PCMG

PCM30/24PCM30/24

Abis

Fig. 2 Asub, Abis and Gb interfaces

BSC architecture


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The switching of traffic channels is the task of the Switching Network SN operating with 16 kbit/s sub channels (e.g. 16 kbit/s = 13 kbit/s + 3 kbit/s for Full Rate speech). While the BSC is transparent for circuit-switched traffic, the (packet-switched) traffic coming from SGSN is adapted by the Packet Control Unit PCU to the 16 kbit/s sub channels used on Abis (e.g. 9.05 kbit/s for CS-1).

TRAU

BSC

SGSN

.

.

.

.

.

.

Asub

Abis

LinkInterface

LinkInterface

SN-1

LinkInterface

LinkInterface

SN-0

3 2 1 0 3 2 1 0

4x16 kbit/sTraffic Channels

4x16 kbit/sTraffic Channels

Gb

Permanent VirtualConnection PVCin Frame Relay

(64 kbit/schannelized)

3 2 1 0

4x16 kbit/sPacket Data

Channels

PacketControl Unit

Fig. 3 BSC traffic channel switching

BSC architecture


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1.2 Signaling information processing The BSC (PCU) processes (external) signaling information coming from the core network:

CCSS#7 signaling between MSC and BSC (for circuit-switched traffic) and BSSGP related signaling between SGSN and PCU (for packet-switched traffic), as well as SBS (internal) signaling:

O&M information and traffic channel signaling to BTSE and TRAU (via LAPD protocol).

BTSE

BSC TRAU MSC

LAPDLAPD

4x16 kbit/s TCH

CCSS 764 kbit/s

CCSS 764 kbit/s

1x64 kbit/s TCH

Abis Asub A

SGSNGb

BSS GPRS Protocol(over Frame Relay)

PCU

Fig. 4 SBS external and internal signaling

BSC architecture


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Signaling Time Slots The following types of signaling time slots are used:

O&M signaling on Abis for the control of the BTSE by the BSC using the LAPD protocol ("LPDLM"),

Traffic channel signaling to BTSE on Abis using the LAPD protocol ("LPDLR", LPDLM and LPDLR do not have to travel on the same time slot),

O&M signaling on Asub for the control of the TRAU by the BSC using the LAPD protocol ("LPDLS"),

Traffic channel signaling on A / Asub between BSC and MSC using CCSS#7 protocol ("SS7L").

For BTSplus max 12 LAPD time slots are available and maximum 8 PCMB links can interface BTSplus and BSC. The BSS GPRS Protocol BSSGP is carried on the same Permanent Virtual Circuit between BSC and SGSN that carries the packet data traffic (no dedicated signaling timeslot is required).

BTSE TRAU

PCMB PCMS

Abis AsubPCMA

A

MSC

SGSNPCMG

Gb

BSSGP

BSC

LPDLM&LPDLR LPDLS CCSS7

PCUUm

Fig. 5 Interfaces and signaling

BSC architecture


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The signaling for circuit-switched traffic (CCSS#7) passes through the TRAU transparently (no transcoding) and is evaluated by the BSC. The BSS Application Part BSSAP comprises

signaling between MS and MSC (passing transparently through the BSC: call control and mobility management) as well as

BSS Management Application Part (for radio resource management, terminated on the BSC).

BTSE

BSC TRAU MSC

LAPDLAPD

4x16 kbit/s TCH

CCSS 764 kbit/s

CCSS 764 kbit/s

1x64 kbit/s TCH

Abis Asub A

Fig. 6 CCSS#7signaling

BSC architecture


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Time slot pattern on PCMA Any sub slots on PCMS that are not subject to transcoding/rate adaptation by the TRAU cause time slots on PCMA to remain empty. Important links that are not transcoded carry:

LAPD signaling (LPDLS), CCSS#7 signaling, Operation and Maintenance Link OMAL (X25A, if used). Additionally, High-Speed Circuit-Switched Data (TRAU pooling) and Nailed-up Connections through the TRAU cause empty time slots on PCMA. The distribution of time slots on PCMA depends on the configuration chosen. Generally speaking, the system clusters the empty time slots "at the back" of the PCMA lines.

BTSE

BSC TRAU MSC

LAPD

CCSS 764 kbit/s

CCSS 764 kbit/s

Abis Asub A

Not used

LAPD

Fig. 7 CCSS7 and LAPD signaling

BSC architecture


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2 Modules

BSC architecture


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The following table includes the BSC/120modules:

Abbreviation Full Module Name

SNAP Switching Network Advance Performances

PPXX Peripheral Processor (all-purpose)

TDPC Telephony and Distributor Processor Circuit

MEMT Memory of the TDPC

MPCC Main Processor Control Circuit

UBEX Universal Bus Extender Board

STLP Superior Trunk Line Peripheral Board

IXLT Interface to LMT/RC

PLLH Phase Locked Loop High Performance

PWRD Power Distributor (Base Shelf)

ESAM Ethernet Switch and Alarm Module

BSC architecture


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Line TerminationxTLP

Line Termination

Line TerminationSwitchingNetwork

SNAP

ClockPLLH

Line Termination

Line Termination

Line Termination

BSSGP

PPXX

BSSGP

PPXX

BSSGP

PPXX

PPXX

MEMT TDPC

Telephony Processors

O&MInterface

IXLT

AdministrativeProcessor

UBEX

MPCC

to OMC

to LMT

PeripheralProcessors

xTLP

xTLP

xTLP

xTLP

xTLP

CPEX

BSSGP

PPXX

BSSGP

PPXX

. . .SS7

+LAPD

PPXX

SS7+LAPD

Fig. 8 BSC internal architecture

BSC architecture


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2.1 Switching network The Switching Network SN comprises a single stage switching matrix which

switches, under the control of the Administrative Processor, the circuit-switched traffic channels between TRAU and BTSE,

switches, under the control of the Administrative Processor, the packet data channels between BTSE, SGSN and PCU ,

routes the signaling timeslots (LAPD and CCSS#7) to/from the peripheral processors (acting as PPXL) via semi permanent connections (nailed-up connections),

is protected by 1:1 redundancy (hot standby). The capacity of the switching matrix is 8 x 8 Mbit/s for SNAP.

BSC architecture


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BTSE

BTSE

LPDLM/R

TRAU

SGSNLineTermination

LineTermination

LineTermination

LineTermination

LAPD

CCS7

SwitchingNetwork

TelephonyProcessor

Peripheral Processors

LPDLS

CCS7

BSC

BSSGPPCU

BSSGP

Fig. 9 Switching network

BSC architecture


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2.2 Peripheral processors The general purpose Peripheral Processor card PPXX is used with appropriate SW load. This means for all purposes the same HW, namely PPXX module is used. The provision of different services (packet switched, LAPD/CCSS7 signaling) is obtained by loading these cards with different software. The Peripheral Processors of type PPXX are multifunctional boards

handling LAPD and SS7 signaling (PPXL, always located in base shelf) acting as Packet Control Unit (PPXU located always in extension shelf) Each PPXX is connected to the SNAP matrix via dedicated 8x8Mbit/s link.

Capacity Each PPXX can handle for processing up to 256 physical channels and is connected via 8Mbps link to SNAP. One PPXL provides 256 signaling channels for LAPD and CCSS#7. Out of this 256 signaling channels up to 16 can be configured as CCSS#7 links and the rest can be configured as LAPD links. One PPXX board configured as PPXU can process up to 256 16kbit/s GPRS channels. The throughput is 4 Mbps per board.

BSC architecture


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Line Termination


SNAP

ClockPLLH

Line Termination

Line Termination

Line Termination

BSSGP

PPXX

BSSGP

PPXX

BSSGP

PPXX

PPXL

MEMT TDPC


O&MInterface

IXLT


UBEX

MPCC

to OMC

to LMT

. . .

PeripheralProcessorsfor CCSS7 and LAPD

xTLP

xTLP

xTLP

xTLP

xTLP

CPEX

PPXL

Fig. 10 Peripheral processor for LAPD and SS7

BSC architecture


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2.2.1 CCSS#7 signaling The Peripheral Processor for CCSS7, PPXX in PPXL operation (former PPCC):

handles CCSS7 MTP layer 2 for the signaling towards the MSC (A interface). The layer 2 is responsible for - error detection - error correction - recovery of a link failure.

PPXL boards support up to 16 CCSS#7 channels each.

BSC architecture


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Line Termination


SNAP

ClockPLLH

Line Termination

Line Termination

Line Termination

BSSGP

PPXX

BSSGP

PPXX

BSSGP

PPXX

LAP D

PPXL

CCSS 7

PPXL

MEMT TDPC


O&MInterface

IXLT


UBEX

MPCC

to OMC

to LMT

. . . PeripheralProcessors

xTLP

xTLP

xTLP

xTLP

xTLP

CPEX

Fig. 11 Peripheral processor for CCSS7

BSC architecture


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2.2.2 LAPD signaling The Peripheral Processor for LAPD, PPXX as PPXL (former PPLD) is responsible for handling the level 2 LAPD protocol (used for signaling on the Abis and Asub interfaces):

O&M signaling between BSC and TRAU: LPDLS O&M signaling between BSC and BTSE : LPDLM Radio signaling between BSC and BTSE (TRX): LPDLR Each PPXL can manage as a maximum 256 physical channels or as the maximum 8Mbps of signaling throughput. This means the LAPD / CCSS#7 signaling capacity (per module throughput) is given by X+0.25*Y+Z

BSC architecture


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Line Termination

Line Termination


SNAP

ClockPLLH

Line Termination

Line Termination

Line Termination

BSSGP

PPXX

BSSGP

PPXX

BSSGP

PPXX

LAP D

PPXX

CCSS 7

PPXX

MEMT TDPC

Telephony Processor

O&MInterface

IXLT


UBEX

MPCC

to OMC

to LMT


xTLP

xTLP

xTLP

xTLP

xTLP

xTLP

CPEX

Fig. 12 Peripheral processor for LAPD

BSC architecture


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2.3 Telephony processor The Telephony Processor is composed of two circuit boards:

TDPC: Telephony and Distributor Processor Circuit, MEMT: Memory of the Telephony Processor which is a memory expansion for the

TDPC and behaves as a mailbox for MPCC - TDPC message interchange.

The Telephony Processor

handles all signaling functions above MTP layer 2 (except for measurement preprocessing, which is performed in the BTSE) and all application processes related to call control, radio resource management, and mobility management,

is connected via an internal bus (Telephony System Bus) to the PPXL (for LAPD and CCSS#7 signaling),

is protected by 1:1 redundancy (hot standby board).

BSC architecture


23

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Line Termination

Line Termination


SNAP

ClockPLLH

Line Termination

Line Termination

Line Termination

BSSGP

PPXX

BSSGP

PPXX

BSSGP

PPXX

LAP D

PPXX

CCSS 7

PPXX

MEMT TDPC

Telephony Processor

IXLT


UBEX

MPCC

to OMC

to LMT

. . . PeriphalProcessors

xTLP

xTLP

xTLP

xTLP

xTLP

xTLP

CPEX

O&MInterface

Fig. 13 Telephony processor (TDPC, MEMT)

BSC architecture


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2.4 Administrative processor The Administrative Processor is comprised of two boards:

MPCC: Main Processor Control Circuit, UBEX: Universal Bus Extender board which interfaces MPCC to switching

network, clock, peripheral processors, and line terminations. The administrative processor (the MPCC actually)

controls the connections of the Switching Network on the basis of the Telephony Processor messages,

handles traffic and performance measurements, is responsible for hardware configuration, is responsible for diagnostic and maintenance management, performs software download, is protected by 1:1 redundancy (hot standby boards) handles 5 external alarms handles IP based O-link between the BSC and RC as well as between BSC and

CBC (Cell Broadcast Center)

provides the connector to Ethernet 10/100 Base T for IP link.

BSC architecture


25

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Line Termination

Line Termination


SNAP

ClockPLLH

Line Termination

Line Termination

Line Termination

BSSGP

PPXX

BSSGP

PPXX

BSSGP

PPXX

LAP D

PPXX

CCS S7

PPXX

MEMT TDPC

Telephony Processor

O&MInterface

IXLT


UBEX

MPCC

to OMC

to LMT


xTLP

xTLP

xTLP

xTLP

xTLP

xTLP

CPEX

Fig. 14 Administrative processor (MPCC, UBEX)

BSC architecture


26

2.5 Line termination The Trunk Line Peripheral boards provide the connections to the

BTSE (PCMB), TRAU (PCMS) and SGSN (PCMG) via standard 2Mbit/s digital lines (coaxial or 4-wire copper). QTLP is used together with SNAP or SN16. STLP is used with SNAP only. QTLP/STLP are n:1 protected:

QTLP - 2:1 in base and 7:1 in extension shelf, hot standby and STLP - 3:1 in base and 7:1 in extension rack, hot standby.

BSC architecture


27

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Line TerminationxLP

Line Termination


SNAP

ClockPLLH

Line Termination

Line Termination

Line Termination

BSSGP

PPXX

BSSGP

PPXX

BSSGP

PPXX

LAP D

PPXX

CCSS 7

PPXX

MEMT TDPC

Telephony Processor

O&MInterface

IXLT


UBEX

MPCC

to OMC

to LMT


xTLP

xTLP

xTLP

xTLP

xTLP

CPEX

Fig. 15 Line termination QTLP or STLP (xTLP)

BSC architecture


28

Configuration QTLP/STLP is also called LICD in the BSC database. A QTLP features 4 ports with 2 terminals each. Thus, QTLP supports

8 PCMx lines (PCMB, PCMS, PCMG) in star configuration, 4 PCMB loops or equivalent combinations. A STLP features 6 ports with 2 terminals each. Thus, STLP supports

12 PCMx lines (PCMB, PCMS, PCMG) in star configuration, 6 PCMB loops or equivalent combinations. Due to these differences the BSC fully equipped with QTLP modules can support up to 72 PCM lines, while this number is increased to 120 PCM lines when STLP modules are used. A port is used in transparent mode when both terminal A and terminal B are used independently. In selection mode, only one of the two terminals (A or B) is used.

BSC architecture


29

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

TRAU 1Port 0 AB

TRAU 2Port 1 AB

TRAU 4BTSE 2

Port 2A

B

BTSE 4Port 3

A

B

BTSE 6 Port 4

A

B

BTSE 7Port 5 AB

TRAU 3

BTSE 3

BTSE 5

Terminal A and BSTLP

BTSE 1

Fig. 16 Mixed configuration of STLP (ports 0 ... 4: transparent mode, port 5: selection mode)

BSC architecture


30

2.6 Hard disk The Hard Disk is used for storing all SBS software (incl. BTSE and TRAU software) and configuration data (BSC database) to allow a fast restart without download from the RC. The Hard Disk is updated every time the database is changed. For redundancy, data are written on both copies. BSC's redundant hard disks are located "on board" the MPCC modules.

History The Hard Disk was originally located on the module DK40 ("Disk 40 Mbytes"). The left DK40 module ("copy 0") is still present in case of the BSC/72 because it also carries the Alarm Circuit controlling the BSC Fuse and Alarm Panel. This function is transferred to new module CPEX in case of BSC/120.

DK 40


Line Termination


SNAP

ClockPLLH

Line Termination

Line Termination

Line Termination

BSSGP

PPXX

BSSGP

PPXX

BSSGP

PPXX

LAP D

PPXX

CCSS 7

PPXX

MEMT TDPC


O&MInterface

IXLTDK 40

to OMC

to LMT



UBEX

MPCC

Hard Disk

xTLP

xTLP

xTLP

xTLP

xTLP

Fig. 17 Hard Disk

BSC architecture


31

Directories The Hard Disk contains a directory tree. For software and database download (e.g. in case of upgrade), the following directories are used:

SWH_DIR/RSUSWLH/n: for storing the software load "n", (e.g. n=0 for BSC, n=1 for BTSE, n=2 for TRAU etc).

SWH_DIR/RSUDB/m: for storing the database file "m", (note: binary database files are named DBFILE.DBA)

TRACE_CTR

TRACE_IMSI

SWH_DIR/RSUDB/0

SWH_DIR/RSUSWLH/2

SWH_DIR/RSUSWLH/1

SWH_DIR/RSUSWLH/0

REMINV

READY_MEAS

READY_CTR

BSC Event Log Files

Perform. Measurem. (active)

CTR Measurements (for upload)

Cell Traffic Records

IMSI Traces

And more . . .

BSC database

Remote Inventory Files

BSC software

BTSM software

TRAU software

Perform. Measurem. (for upload)

MEASURE_DIR

LOG

. . .

. . .

Fig. 18 System directories on Hard Disk

BSC architecture


32

2.7 CPEX / ESAM Each CPEX/ESAM board supports up to 16 external alarms in addition to the 5 already handled by the main processor board (MPCC). The CPEX can only be used in the BSC120. ESAM can be used in BSC72 and BSC120. The CPEX/ESAM board is placed in the slot former used for the DK40. The Control Panel supervision functions of the DK40 are taken over by the CPEX/ESAM in addition to its function regarding external alarms handling. CPEX/ESAM is connected to the administrative bus. The ESAM includes all functionalities of CPEX and in addition it is required in case of the Gb Interface realized with IP link. One ESAM supports the IP interfaces to all PPXX boards (maximum is 12) and 2 IP interfaces towards SGSN or external router.

BSC architecture


33

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Line TerminationSTLP

Line Termination


SNAP

ClockPLLH

Line Termination

Line Termination

Line Termination

LAP D

PPXX

CCS 7

PPXX

MEMT TDPC


O&MInterface

IXLT


UBEX

MPCCto LMT


STLP

STLP

STLP

STLP

STLP

. . .

ESAM

BSSGP

PPXX

. . .

BSSGP

PPXX

BSSGP

PPXX

BSSGP

PPXX

to SGSN

. . .

to Peripheral Processors

Fig. 19 Control panel and external alarms device (CPEX)

BSC architecture


34

2.8 O&M interface IXLT The Interface X.25 and Local Maintenance Terminal IXLT board connects the administrative processor to the operation and maintenance center RC (called Radio Commander since release BR6.0) and to the local maintenance terminal LMT. Operators, which currently have applied a X.25 network, now can replace their X.25 network by an IP network, which significantly speeds up the O-link. The IP based O-link is introduced in addition to the already supported X-25 link. The BSC supports either X.25 or IP. The BSC is equipped with two connectors to support either X.25 links or IP links in an exclusive way. In case of X.25 the cable will be connected to the already existing IXLT (Interface X.25 Local Terminal). In case of IP it will be connected to the MPCC board, but in all case the IXLT board is needed. IXLT is protected by a (cold) standby module.

BSC architecture


35

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Line Termination

Line Termination


SNAP

ClockPLLH

Line Termination

Line Termination

Line Termination

BSSGP

PPXX

BSSGP

PPXX

BSSGP

PPXX

LAP D

PPXX

CCSS 7

PPXX

MEMT TDPC

Telephony Processor

O&MInterface

IXLT


UBEX

MPCC

to LMTV.2/V11


xTLP

xTLP

xTLP

xTLP

xTLP

xTLP

CPEX

to RCX.25A orX.25D to RC

IP/TCP

Fig. 20 O&M interface on IXLT

BSC architecture


36

2.9 Clock unit The Phase Locked Loop High Performance PLLH clock:

is based on a high stability quartz oscillator that provides all of the system timing works in free running mode, or synchronized to external clock sources relies on two identical redundant boards PLLH working in master/slave

configuration.

BSC architecture


37

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Line Termination

Line Termination


SNAP

ClockPLLH

Line Termination

Line Termination

Line Termination

BSSGP

PPXX

BSSGP

PPXX

BSSGP

PPXX

LAP D

PPXX

CCSS 7

PPXX

MEMT TDPC

Telephony Processor

O&MInterface

IXLT


UBEX

MPCCto LMT


xTLP

xTLP

xTLP

xTLP

xTLP

xTLP

CPEX

Fig. 21 Clock PLLH

BSC architecture


38

2.10 Packet control unit The Packet Control Unit required for packet switched data handling (GPRS / EGPRS) is located in the BSC. The main PCU functions are

Radio channel management and Protocol conversion between standard BSS GPRS protocol BSSGP (over Frame

Relay, on Gb) and proprietary Abis protocol. While the Gb interface has multivendor capabilities, the Abis interface is proprietary using a PCU frame format (an extension of existing TRAU frames). The PCU frames have a uniform length of 320 Bit and are transferred every 20 ms via the Abis interface (16 kbit/s). Thus, the PCU performs statistical multiplexing and routing. The PCU load is automatically distributed between the available PPXX modules working as PPXU. If a PPXU fails, the GPRS/EGPRS load is automatically distributed between the remaining PPXU modules.

BSC architecture


39

SGSN

BSC

PCU

PCU tasks Management of GPRS radio resources Protocol conversion (packet data interworking) Tasks comparable to classical BSC Remote (until now BTS tasks): PC, TA,...

Gb:standard interface

BTSE

Abis:proprietary

i/fi/f

Fig. 22 PCU functions

Cell A

Cell B

Cell C

Cell D

Cell E

Cell F

PPXU-0 PPXU-1 PPXU-2

GPRS traffic is automatically distributed among (working) PPXUwell balanced in case of failure, packet traffic is automatically redistributedamong the remaining PPXU (load sharing)

To SGSN

Fig. 23 Load sharing between PPXU

BSC architecture


40

2.11 Bus systems Three bus systems are implemented on the BSC backplane:

Telephony System Bus: Connects the peripheral processors (PPXX) with the TDPC.

Administrative System Bus: Connects the TDPC to the MPCC and the MPCC to the IXLT and CPEX.

Administrative Extended Bus: Used as an O&M connection between MPCC (via UBEX) and PPXX, SNXX, PLLH and XTLP.

BSC architecture


41

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .


Line Termination


SNAP

ClockPLLH

Line Termination

Line Termination

Line Termination

BSSGP

PPXX

BSSGP

PPXX

BSSGP

PPXX

LAP D

PPXX

CCSS 7

PPXX

MEMT TDPC


O&MInterface

IXLT


UBEX

MPCC

to OMC

to LMT

. . .

TelephonySystem Bus

AdministrativeSystem Bus

AdministrativeExtended Bus

AdministrativeExtended Bus

xTLP

xTLP

xTLP

xTLP

xTLP

CPEX

Fig. 24 Bus systems

BSC architecture


42

BSC architecture


43

3 BSC Connections

BSC architecture


44

3.1 Local Maintenance Terminal The proprietary interface between LMT and BSC (T interface) is based on X.21/V.11 using LAPB and HDLC protocol.

BSC architecture


45

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

MSC

BTSE

BSC

LMT

IXLT

X.21/V.11

TRAU

SBS

Fig. 25 Connection BSC - LMT

BSC architecture


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3.2 Operation and Maintenance Link The radio commander supports both X.25 networks and IP networks. So the system upgrade from X.25 networks to IP networks can be done smoothly and stepwise (BSC per BSC). The BCS connection to the RC is the O-link which can be realized by

a dedicated line through a X.25 packet data network PSDN , X.25D interface a 64 kbit/s time slot on PCMA/PCMS (nailed-up connection through the MSC),

X.25A interface

IP based O-link For redundancy two independent O-Links are supported (active-cold standby). The redundant OMAL always has to be of the same kind as the primary link.

BSC architecture


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. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

IXLT-0

IXLT-1

Hub or Switch or Router

RC

CBC

LMT LAN

X

IP-0X.25 Dedicated

X.25 Dedicated

X.25 PCM Timeslot

X.25 PCM Timeslot

BSC

LMT V.11 64Kbit/sec

Standby MPCC-1

Active

MPCC-0

Test only

Fig. 26 IP based O-Link

BSC architecture


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3.3 Gb interface

3.4 High speed Gb Interface The Gb interface can be realized by FR over E1/T1. The connection can be done in 4 different ways.

NUC through MSC to the SGSN NUC through MSC and then via Frame Relay network to the SGSN. a direct line and then via Frame Relay network to the SGSN a direct connection to the SGSN. The other opportunity is the realization of the Gb Interface over IP. Fast Ethernet (up to 100 Mbps) and Gigabit Ethernet (up to 1 Gbps) with IPv4 are supported. The standard is Ethernet II or IEEE802.3.

BSC architecture


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. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

PCUBSC Frame Relay

networkSGSN

MSC

E1/T1-Line

E1/T1-Line

E1/T1-Line

E1/T1-Line

1

2

3

4

TRAU

PCU SGSN

ESAM

R WAN R

Ethernet

Fig. 27 The different realization possibilities of the Gb interface

BSC architecture


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BSC architecture


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4 Rack configuration

BSC architecture


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4.1 Module combinations The following hardware configurations are supported:

BR9.0 QTLP STLP

SNAP SNAP

PPXX ("PPXL") PPXX ("PPXL")

PPXX ("PPXU") PPXX ("PPXU")

PWRS

Hardware Configuration Capacity (per BSC, fully equipped) QTLP / SNAP / PPXX 24 Mbit/s

STLP / SNAP / PPXX 48Mbit/s

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4.2 Rack layout The BSC consists of the Base and Expansion Subracks located in the same rack:

The Base Subrack represents the minimum configuration. The Expansion Subrack provides additional link interface modules QTLP/STLP

and the PCU for GPRS/EGPRS. There are different examples for BSC Rack Configuration shown:

The BSC equipped with the QTLP/SNAP/PPXX modules is the "High Capacity 1st Step 1" BSC or BSC72.

The BSC equipped with the STLP/SNAP/PPXX modules is the "High Capacity 2nd Step" BSC or BSC120.

All Hardware configurations can be used with the BR9.0 Software. The capacity depends on the modules that are used.

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4.2.1 BSC high capacity 1st step The Base Rack is full equipped with the mandatory modules. In the High Capacity 1st Step Configuration the Switching Network SNAP is used. The Line Trunk Cards are all QTLP. The Expansion Subrack has additional space for link modules and peripheral processors:

7 + 1 QTLP 6 PPXX 2 PWRS The Peripheral Processors in the Base Rack is 2 PPXL Modules, that handle the complete LAPD and CCSS7 signaling amount. The Peripheral Processors in the Expansion Subrack are optional 1 to 6 modules, that handle the packet switched traffic.

Notes The BSC72 supports 8 SS7 links with 2 PPXL boards in load sharing mode.

BSC architecture


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Lamp Panel

QTLP8

QTLP7

QTLP6

PPXX7

PPXX6

PPXX5

QTLP5

QTLP4

QTLP3

PPXX4

PPXX3

PPXX2

QTLP2

QTLPS1

PWRS1

PWRS0

PLLH0

QTLP1

PPXX0

PLLH1

QTLP0

PWRS1

PWRS0

QTLPS0

PPXX1

DK400

IXLT0

UBEX0

SNAP0

TDPC0

MEMT0

MPCC0

MPCC1

MEMT1

TDPC1

SNAP1

UBEX1

IXLT1

Expansion

Fuse and AlarmPanel

Base

Fig. 28 BSC rack (BSC High Capacity 1st Step)

BSC architecture


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4.2.2 BSC high capacity 2nd step The modules introduced with the BSC120 are: The Line Trunk Peripheral Boards type STLP (mandatory) The CPEX/ESAM module handling 16 additional External Alarms and performing

Control Panel supervision function

Power Supply modules used only in Base Subrack. The Expansion Subrack has additional space for link modules and peripheral processors:

7 + 1 STLP 12 PPXX The PPXX modules in the Expansion Rack are only used for GPRS/EGPRS. Superior Trunk Line Peripheral STLP boards support 6 Ports on each board with terminal A and B per port.

TIP For the Gb link via IP the modules ESAM and PPXX_V2 are required.

BSC architecture


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ESAM

0

IXLT

0

UBEX

0

SNAP

0

TDPC

0

MEMT

0

MPCC

0

ESAM

1

IXLT

1

UBEX

1

SNAP

1

TDPC

1

MEMT

1

MPCC

1

PWR

1

PLLH

1

PWR

0

PLLH

0

STLP

1

STLP

0

STLPS0

STLP

2

PPXX

1

PPXX

0

STLP

5

STLP

4

STLP

3

STLPS1

STLP

9

STLP

8

STLP

7

STLP

6

PPXX

7

PPXX

6

PPXX

5

PPXX

4

PPXX

3

PPXX

2

PPXX

13

PPXX

12

PPXX

11

PPXX

10

PPXX

9

PPXX

8

Expansion Subrack

Base Subrack

Fuseand Alarm Panel

Fig. 29 BSC Rack (BSC High Capacity 2nd Step)

BSC architecture


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4.3 Redundancy concept For reliability, certain modules are duplicated. There are the following opportunities for redundancy:

1:1 redundancy: one module is providing service, the other one is in spare module n:1 redundancy all modules are combined to a

03 RA22123EN09GLS0 Bsc Architecture

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