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GSM OVERVIEW

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SWITCHING SYSTEM

Mobile Services Switching Center (MSC)-MSS MGW, Gateway MSC (GMSC)

The MSC is responsible for setting up, routing and supervisingcalls to and from the mobile subscriber.

The GMSC is a MSC serving as an interface between the mobile network and other networks such as the PSTN and ISDN.

All MS terminated calls are set up via the GMSC.

Home Location Register (HLR)The HLR is a database for storing subscriber information specific to that PLMN. Subscriber information includes location information and information on services assigned to subscribers

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SWITCHING SYSTEM CONT’DVisitor Location Register (VLR)The VLR temporarily stores information about the MS currentlyvisiting its service area. In the system the VLR is integrated withMSC in the same AXE 10 switch.

The HLR can be implemented in a stand alone AXE 10 switchor an integrated (G)MSC/VLR/HLR.

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SWITCHING SYSTEM CONT’D

Authentication Center (AUC)The AUC generates triplets used in the authentication of asubscriber SIM card and ciphering of speech, data and signalingover the air-interface.

Equipment Identity Register (EIR)In GSM/PCS, there is a distinction between subscription andaccess. The EIR is a database responsible for validation ofmobile equipment.

Service Center (SC)The SC is responsible for reading, storing and forwarding ashort message between a short message sender and a MobileStation. Ericsson offers a SC as a combined messaging system(e.g. voice, fax), on a MXE platform.

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SGSN AND GGSN

• Gateway GPRS Support Node is the interface towards the external IP packet networks. The GGSN contains access functionality that interfaces external ISP functions like routers and RADIUS servers.

• The GGSN acts as a router for the IP addresses of all subscribers served by the GPRS network.

• Serving GPRS support node: forwards incoming and outgoing IP packets to or from a mobile station within the SGSN area

• Ciphering and authentication• Connection to HLR, MSC, BSC• Collection of Charging information

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OSS

Operation and Support System (OSS)The OSS is Ericsson’s product for the GSM/PCS Operationand Maintenance Center (OMC).

For GSM system administration, OSS supports the operator with functions suchas mobile subscriber and cellular network administration and alarm handling. OSS is implemented through Ericsson’s.Telecommunications Management and Operations Support(TMOS) system.

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BASE STATION SYSTEM (BSS)

Base Station System (BSS)The BSS is divided into the following functional units:

Base Transceiver Station (BTS)The BTS is the radio equipment needed to serve one cell.

The BTS is the radio equipment, which transmits and receives information over the air to allow the BSC to communicate with MSs in the BSCs service area. A group of BTSs is controlled by a BSC. The BTS must contain GPRS-specific software. The BSC provides all radio-related functions.

It contains the antenna system, radio frequency power amplifiers and digital signaling equipment. Ericsson’s product for the BTS is the Radio Base Station (RBS).

System versions:· RBS 200 for GSM· RBS 2000 for GSM

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MTN Ghana Base Station Controller (BSC)

The BSC controls and supervises a number of RBSs and radio connections in the system. It handles the administration of cell data, the locating algorithm and orders handovers.

The BSC has the functionality to set up, supervise, and disconnect circuit switchedand packet-switched calls.

It is a high capacity switch that provides functions including handover, cell configurationdata, and channel assignment. The BSC must be equipped with GPRS hardware and software when used for GPRS

• I/O SYSTEM• CENTRAL PROCESSOR• REGIONAL PROCESSORS

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GSM IDENTITIES

MOBILE STATION ISDN NUMBER (MSISDN)

The MSISDN is a number which uniquely identifies a mobile telephone subscription in the public switched telephone network numbering plan.

MSISDN consists of the following:MSISDN = CC + NDC + SN

CC Country Code

NDC National Destination Code

SN Subscriber Number

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IMSI

The IMSI is a unique identity allocated to each subscriber toallow correct identification over the radio path and through theGSM PLMN network and is used for all signaling in thePLMN.

All network-related subscriber information is connectedto the IMSI. The IMSI is stored in the SIM, as well as in theHLR and VLR.

The IMSI consists of three parts:IMSI= MCC + MNC + MSIN

MCC Mobile Country Code

MNC Mobile Network Code

MSIN Mobile Station Identification Number

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TMSI AND EMEI

TEMPORARY MOBILE SUBSCRIBER IDENTITY (TMSI)The TMSI is used to protect the subscriber’s privacy on the airinterface.

The TMSI has only local significance (that is, withinthe MSC/VLR area) and hence its structure can be determinedby each operator.

INTERNATIONAL MOBILE EQUIPMENT IDENTITY (IMEI)The IMEI is used for equipment identification and uniquelyidentifies a MS as a separate piece or assembly of equipment

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MTN Ghana AIR INTERFACE AND CHANNEL CONCEPT

  GSM DCS 1800 PCS 1900

Uplink 890 - 915 MHz 1710 - 1785 MHz 1850 - 1910 MHz

Downlink 935 - 960 MHz 1805 - 1880 MHz 1930 - 1990 MHz

• Carrier separation is 200kHz, with bandwidth of 25MHZ which gives 125radio channels.• 1 channel used for separation of GSM frequencies from other applications e.g 889• 124 carriers in the GSM band

Since each carrier is shared by eight MSs, the total number ofchannels are:

• 124 x 8 = 992 channels in GSM

Each of these channels, that is one time slot on a Time DivisionMultiple Access (TDMA) frame

In GSM TDMA frame consists of 8 timeslots-burst info sent in one time slot-51,26 TDMAFrame-1 hyperframe = 2048 superframes = 2,715,648 TDMA frames

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LOGICAL CHANNELS

LOGICAL CHANNELSThere are 12 logical channels in the system. Two are used fortraffic, nine for control signaling and one for messagedistribution.

Traffic channels (TCH)There are two types of TCHs:· Full rate channel, - used for full rate speech at 13kbit/s or data up to 9.6kbit/s

· Half-rate channel, - used for half rate speech at 6.5kbit/s or data up to 4.8kbit/s

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BROADCAST CONTROL CHANNELSControl channelsThere are nine types of control channels. They are:Broadcast Channels (BCH) (Downlink Only)

· Frequency Correction Channel (FCCH) - used forfrequency correction of MS-identifies BCCH carrier

· Synchronization Channel (SCH) - carries informationabout the TDMA frame number and the Base StationIdentity Code (BSIC) of the BTS-ensure GSM BTS is chosen

· Broadcast Control Channel (BCCH) - Broadcasts cellspecific information to the MS-max power, BCCH of neighbours

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COMMON CONTROL CHANNELS (CCCH)

Paging Channel (PCH) - used over the downlink to pagethe MS

· Random Access Channel (RACH) - used over the uplinkby the MS to request allocation of a SDCCH, either as apage response or an access at MS call origination/registration

· Access Grant Channel (AGCH) - used on the downlink toallocate a SDCCH or TCH to a MS

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Dedicated Control Channels (DCCH) (Uplink and Downlink)

• Stand alone Dedicated Control Channel (SDCCH) – used for system signaling during call setup or registration, uplink and downlink, as well as the transmission of short text messages in idle mode

Slow Associated Control Channel (SACCH) – control channel associated with a TCH or a SDCCH. Measurement Reports from the MS to the BTS are sent on the uplink .On the downlink the MS receives information from the BTS on what transmitting power to use and also instructions on Timing Advance(TA). The SACCH is also used for the transmission of short text messages in call connected (busy) mode.

Fast Associated Control Channel (FACCH) – Control channel associated with a TCH. Also referred to as Fast Associated Signaling (FAS), the FACCH works in stealingmode. That is, 20 ms of speech is replaced by a control message. It is used during handover as SACCH signaling is not fast enough. Used over uplink and downlink.

Cell Broadcast Channel (CBCH)Used only on the downlink to carry Short Message Service Cell Broadcast (SMSCB). Uses the same physical channel as the SDCCH

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MTN GhanaBSC/TRC HARDWARE AND BASIC CONCEPTS

TRC - a Stand Alone transcoder controller node. The TRC node allows a flexible location of the transcoder resources. Typically, the TRC is located at or near the MSC. It is controlled by the BSC. 16 BSCs can be connected to oneTRC.

· BSC/TRC - a combined BSC and transcoder controllerThe BSC/TRC is suitable for medium and high capacity BSC applications, that is, urban and suburban area networks. This node can handle up to 1,020 Transceivers (TRXs). 15 standalone BSCs can be connected to the BSC/TRC.

· BSC - a Stand Alone BSC without transcoders. The BSC is optimized for low and medium capacity BSS networks and is a complement to the BSC/TRC, especially in rural and suburban areas. For GSM 900/GSM 1800, it can handle up to 1,020 TRXs.

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BSC/TRC HARDWARE AND BASIC CONCEPTS

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• Exchange Terminal Circuit (ETC) · Signaling no.7 terminal (ST7, C7-ST) · Transcoder and Rate Adaptor (TRA) · Transceiver Handler (TRH)· Subrate Switch(SRS)

· DEV• Hardware connected to GS is referred to as device hardware• ETC board is common hardware in AXE to handle PCM transmission

links-2Mbit/s. ETC5 board handles 2Mbits/s.• Boards towards MSC differ from boards towards RBS via software

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GROUP SWITCH

GROUP SWITCH (GS)• Central part of the BSC/TRC. • Connects an incoming channel with an outgoing channel. • Can switch down to 64 kbit/s. • Switching to lower bitrates, for example, 16 kbit/s, the SubRate Switch (SRS) must be used.

Switching Network Terminal (SNT)• All equipment connected to the group switch uses the same standardized

interface-Switching Network Terminal (SNT). • SNT is a software concept • Represents software connection of the physical hardware to the Group Switch. • The hardware is normally referred to as device hardware. Each SNT is

connected to the GS at a Switching Network Terminal Point (SNTP).• NTCOP:SNT=ALL;

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RBLT,RALT, ETC155MB/S

RBLT Devices• Each Time Slot (TS), which is 64 kbit/s, on the PCM link towards the

RBS is called an RBLT device.• The device is a resource that the BSC can store information on. In this

case it is either LAPD signaling or speech towards the RBS.• 32 RBLT devices on an E1 PCM link and 24on a T1 PCM link.• 32 RBLT devices from 1 to 31for first dip• RBLT-0 device is used for synchronization• RXAPP:MO=RXOTG-8;

RALT Devices• Time slot which is 64kb/s on the PCM link towards the MSC is known

as RALT.

ETC 155 hardware can be used for connecting differentswitches to the SDH transport network. The interface may beoptical fibers or electrical cables.

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TRANSODER AND RATE ADAPTOR

• The TRA is the function responsible for the speech coding and rate adaption of incoming speech and data from the MSC and the RBS.

• Hardware where the function is implemented is calledTranscoder and Rate Adaption Board (TRAB).

• FUNCTIONS:• Transcoding of speech information• Speech at 64kbits/s MSC to 13kbits/s RBS• Enabling compressed speech to be multiplexed• Full rate or enhanced full rate 13/15.1 kbits/s• Half rate transcoded at 6.5kbits/s

• CONTROL INFORMATION• FR=3kbits/s• EFR=0.9kbits/s• HR=1.5kbits/s• Control information(in-band) signaling tells whether the information contains data

or speech

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• Six MUXs handle 24 multiplexed channels towards theBTS.

• 24 DEMUXs handle the demultiplexed channels towards theMSC

• In terms of hardware, a TRA-EM consists of 32 devices,requires 32 GS inlets, and can handle 24 TCHs.

• Transcoders can be connected in pool

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Transcoder in pool

• In a transcoder pool the group switch connects the transcoders only during the calls• Advantage:

– Less transcoder HW is needed– Redundancy

BSC/TRCBTS 1

BTS 2

BTS nTRA n

TRA 1 TRA 2

Transcoder pool

Group SwitchPSTN

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Semi-permanent connection

• A semi-permanent connection is if all transcoders are continuously connected to the same base station.

• Disadvantage:– If a transcoder board gets faulty the BTS can´t be used– For every possible connection there has to be a transcoder

BSC/TRC

TRA 1

TRA 2

TRA n

BTS 1

BTS 2

BTS n

PSTN

1

n

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TRANSCEIVER HANDLER

The TRH performs the activities that are required to control the RBS and the transceivers. The main function of the TRH is to implement LAPD signaling functions from the BSC to the transceivers.

• Handling of signaling on the Link Access Protocol on the Dchannel(LAPD) link between BSC-BTS.

• Handling of logical channel addressing part of signaling to/from the BTS and mobile stations (MS).

• Processing of measurement data from the BTS and MSs

• Operation and maintenance of the BTS.

• Each transceiver in the RBS must have a signaling connectiontowards the BSC.

• The device handling the signaling connection towards the RBS is the RHDEV. One RHDEV is semipermanently connected to one transceiver in the RBS.

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LAPD links are provided for:• Radio Signaling Link (RSL) - which serves Traffic• Management Procedures of Level 3-Network

• Operation and Maintenance Link (OML) - which serves• Network Management Procedures of Level 3 (used for BTS• O&M messages)-Network

• Layer 2 Management Link (L2ML) - which serves the• Level 2 Management Procedures and used for management of data links

sharing a physical connection-DL

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• TRUs in the RBS are referred to as terminal equipment. Each data link is identified by a TEI/SAPI pair unique for each physical connection.

• Each physical connection can support a number of data links • · Terminal Endpoint Identifier (TEI) - signaling links over the A-bis interface are

addressed to different physical entities by TEI

• · Service Access Point Identifier (SAPI) – different functional entities within one physical entity are addressed by SAPI

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SUBRATE SWITCH

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CONT’D

• SUBRATE SWITCH ALLOWS FOR CONNECTION OF RATES LOWER THAN 64KB/S• FOUR 64 kb/s TS that contain speech arrive from the MSC• TRH controls the call setup and determines whether SRS should be used, which TRA should

be used, the call type, destination BTS.• THE GS Sets up connections towards the TRA• Transcoder transcodes four 64kb/s channels into four 16kb/s channels, multilplexed onto one

64kb/s and returned to the GS• TRH determines the destination that SRS should be used to and GS sets up connection to

SRS• The SRS switches 2 16kb/s channels onto two 64kb/s channels

SIGNAL TERMINAL NO.7 (ST7)• The MSC must have the ability to signal with the BSC. • This is done using Signaling Terminals (ST).

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PROCESSORS (RP AND CP)

• PROCESSORS (RP AND CP)• The RPs are designed to execute simple high-repetition functions and are mainly

used for the direct control of the hardware units of the application systems. These hardware-units offer the traffic devices of the exchange, for example, ETC,TRA

• The CPs execute complex and data demanding tasks• The standard RPs are called either RPM6A or RP4

Regional Processor Group (RPG)The RPG has higher capacity . The RPG, with different softwareloaded, can, in the BSC, serve as TRH, C7, or STC terminal.

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SOME USEFUL COMMANDS

• RELATED COMMANDS• NTCOP - Switching Network Terminal, Connection Data, Print• NTSTP - Switching Network Terminal, State, Print• EXRPP - Exchange Data Functions RP, Print• EXEMP - Exchange Data, EM, Print• EXRUP - Exchange Data Functions, RP Software Unit Data, Print• STDEP - Device State for Devices, Print• DTDIP - Digital Path Transmission Functions, Digital Path, Print• DTSTP - Digital Path Transmission Functions, State, Print• RADEP - Radio Control Administration Device Data, Print• RRTPP - Radio Transmission Transcoder Pool, Print

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GEM

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High Density BSC

Scalable and Expandable– Up to 4095 TRXs– Up to 18000 Erlang

IP Support on all Interfaces

1 cabinet BSC supports up to 1024 TRXs

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EGEM

High Density BSC

eGEM Technology

APZ 212 55 as Central Processor

APG 43 as I/O System

GPHB for the PCU application

TRHB for the TRH application

GARP2 for the PGW application

STEB for SS7 Signaling

NWI-E as Ethernet Interface

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EGEM WITH APG43 AND APZ 212 55

Slot 0: SCP-RP4, not part of the APG43. Used for the eGEM switching. Slot 4: GEA, Generic Ericsson Alarm board, optional board, common for APG43 nodes; Slot 5-6: GEP: CPUB0A, processor board for APZ 212 55 node side A;Slot 7: MAUB, MAU processor board for APZ 212 55;Slot 8-9: GEP: CPUB0B, processor board for APZ 212 55 node side B;Slot 10-11: GEP: APUB 0A, processor board for APG43 node side A;Slot 12-13: GED: HDD 0A, hard disk board for APG43 node side A;Slot 14-17: Media 0, optional board with DVD, common for APG43 nodes;Slot 18-19: GEP: APUB 0B, processor board for APG43 node side B;Slot 20-21: GED: HDD 0B, hard disk board for APG43 node side B;Slot 25: SCP-RP4, not part of the APG43. Used for the eGEM switching.

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TIME SLOT ALLOCATION ON ABIS-BPC

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MANAGED OBJECT

A MO is a logical representation of hardware units and software in the BTS.

Transceiver Group (TG)

Central Function (CF)

Digital Path (DP)

Transceiver Controller (TRXC) Transmitter(TX)

Receiver (RX)

Interface Switch (IS)

Timing Function(TF)

Time slots (TS)

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DISTRIBUTION SWITCH UNIT (DXU)• The Distribution Switch Unit (DXU) is the RBS central control unit. • There is one DXU per RBS. • It provides a system interface by cross-connecting either a 2Mbit/s transport

network and individual time slots to their associated transceivers.

TRANSCEIVER UNIT (TRU)• The TRU is a transmitter/receiver and signal-processing unit, which

broadcasts and receives the radio frequency signals that are passed to and from the mobile station.

• Each TRU handles eight air time slots

COMBINING AND DISTRIBUTION UNIT (CDU)• A combiner is a device, at the base station, that allows for the connection of

several transmitters to one antenna.• It allows each transmitter RF energy out to the antenna, while blocking the

RF energy from other transmitters utilizing the same antenna. There are two combiner types: Hybrid, Filter

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ENERGY CONTROL UNIT (ECU)

The ECU controls and monitors the power and climate equipment to regulate the power and the environmental conditions inside the cabinet to maintain system operation. It communicates with the DXU over the Local Bus.

The main units of the power and climate system are: · Power Supply Units (PSU) · Battery and Fuse Unit (BFU) with batteries · AC Connection Unit (ACCU) · Climate sub cabinet with Climate Control Unit (CCU), heater, active cooler, and

heat exchanger (outdoor cabinets only) · Fans controlled by Fan Control Units (FCU) · Climate sensors, that is, temperature and humidity sensors

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LOCAL BUSThe local bus offers internal communication between the DXU, TRUs, and ECU. Examples of information sent on this bus are TRX Signaling, speech and data.

TIMING BUSThe timing bus carries air timing information from the DXU to the TRUs.

X-BUSThe X-bus carries speech/data on a time slot basis between theTRUs. This is used for base band frequency hopping.

CDU BUSThe CDU Bus connects the CDU to the TRUs and facilitatesinterface and O&M functions, for example, transfers alarms andRU specific information.

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The DXU is divided into four main sections. These are:

· PCM-part, Represents the Managed object Interface Switch(IS) and the Digital Path (DP)

· Central Processing Unit (CPU), Represents the Managed

object Central Function (CF)

· Central Timing Unit (CTU), Represents the Managed object

Timing Function (TF)

· High level Data Link Controller (HDLC) concentrator,represents the Managed object Concentrator (CON).

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DIP NAMINGDigital Path (DIP)• Digital Path (DIP) is the name of the function used for supervision of the connected

PCM lines.

• ITU-T has issued recommendations which state how the PCM links should besupervised. All these recommendations are implemented in the DIP function and the ETC. • Depending on whether the PCM link goes toward the MSC or the RBS the DIP will

have different names. RALT towards the MSC and RBLT towards the RBSs. RBLT stands for RTS A-Bis interface Line Terminal

• RALT stands for RTS A-interface Line Terminal.

• DTSTP:DIP=ALL;• DTDIP:DIP=5RAL2;• NTCOP:SNT=ETM2-0;

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MO ADDRESSINGFUNCTION MO CLASS MO-G12TG Transceiver Group (TG) RXOTG

CF Central Function (CF) RXOCF

IS Interworking Switch (IS) RXOIS

DP DIP Supervision (DP) RXODP

CON LAPD Concentration (CON) RXOCON

TM Time Module (TM) RXOTF

TRXC TRX Controller (TRXC) RXOTRX

RRX Radio Receiver (RRX) RXORX

RTX Radio Transmitter (TRX) RXOTX

SPP Time Slot (TS) RXOTS

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MANAGED OBJECT STATES

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RELATED COMMANDSRXMOP - Radio X-ceiver Administration Managed Object Data, Print

RXMSP - Radio X-ceiver Administration Managed Object Status, Print

RXMOI - Radio X-ceiver Administration Managed Object, Initiate

RXMOC - Radio X-ceiver Administration Managed Object Data, Change

RXESI - Radio X-ceiver Administration Managed Object in Service, Initiate

RXBLE - Radio X-ceiver Administration Manual Blocking of Managed Object, End

RXCDP - Radio X-ceiver Administration Managed Object Configuration Data, Print

RXMDP - Radio X-ceiver Administration Managed Object Device Information, Print

RXPLI – Radio X-ceiver Administration Function Change and Program Load of Managed Objects, InitiateRXMSC - Radio X-ceiver Administration Managed Object inservice Data, Change

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ABIS ADDRESSINGTerminal Endpoint Identifier (TEI) - signaling links over the A-bis interface are addressed to different physical entities by TEI

· Service Access Point Identifier (SAPI) – different functional entities within one physical entity are addressed by SAPI

Each physical connection can support a number of data links.These links are supported and used:

· L2ML -Layer 2 Management Link, for O&M of the links.· OML -O&M Link, for O&M of the BTS equipment.· RSL -Radio Signaling Link, for transmission of traffic messages.

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OML links are used for TRH-CF and TRH-TRXC signaling.

RSL links are used for TRH-TRXC signaling to SDCCH,BCCH, etc.

The TEI value for CF is default set to 62, but can be changed inthe range from 12 to 63 using the OMT terminal. This must be done, if several RBSs are cascaded and share one PCM link.

The TEI values for the TRUs range from 0 to 11.

The TEI value is dependent on the position of the physical position of the TRUin the cabinet.

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MTN GhanaDIGITAL CONNECTION POINTS (DCP)

The connection of the control and speech/data channels from the RBLT devices through the IS in the DXU to the TRXs is automatically established when the TRXs are taken into service

(command RXESI).

The connections for the units are called DCPs and these represent a 64 kbit/s connection.

Which DCPs should be connected to a particular TRU (command RXMOI).

· Which DCPs should be connected to the CON (command RXMOI).

· Which RBLT devices should be connected to a particular TG (command RXAPI).

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TRU DCPsEach TRU has three DCPs.

DCP1 is the connection for signaling. Two DCP2 for traffic connections.

TRU0 has DCP1 connection 128 and DCP2 129 and 130.

CON DCPsThe concentrator is connected with 24 DCPs from 64 to 87.

RBLT Device DCPsPCM-A is connected to DCPs 1-31, and PCM-B is connected toDCPs 33-63.

The connection for the synchronization timeslot, TS 0, need not be defined for E1 PCM systems..

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LAPD UNCONCENTRATED

An RBS with four TRUs used. This means that 12 devices on the PCM link must be used, three to each TRU.

RBLT devices 97 to 108, which means that the DIP is RBLT-3, are connected to DCP 1 to 12.

Signaling and the speech/data are distributed to the right TRU through the IS.

The signaling for TRXC-0 and the CF is on the same TS.

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LAPD UNCONCENTRATED

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LAPD CONCENTRATION

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BSS HARDWARE OVERVIEW

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RXAPP - Radio X-ceiver Administration ABIS Path Status, Print

RXAPI - Radio X-ceiver Administration ABIS Path, Initiate

RXMOP - Radio X-ceiver Administration Managed Object, Print

RXMOI - Radio X-ceiver Administration Managed Object, Initiate

RXMDP - Radio X-ceiver Administration Managed Object Device Information, Print

DTSTP - Digital Path Transmission Functions State, Print

DTDII - Digital Path Transmission Functions Digital Path,Initiate

DTBLE - Digital Path Transmission Functions Blocking, End

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INTRODUCTION TO THE CELL

A cell is an area where a Mobile Station (MS) receives a signal strength which is high enough to set up a radio connection on a dedicated channel, that is, the SDCCH or TCH and maintain it.

The cell size (or the size of the coverage area) is mainlydetermined by four parameters:

· The output power (BSTXPWR) at the antenna of the BTS:the Effective Radiated Power (ERP)

· The minimum received level at the MS (this is MSRXMINfor MS in “busy” mode)

· The minimum received level at BTS (BSRXMIN)

· The Timing Advance (TA): The TA is a measure of thetraveling time of the bursts between the MS and BTS; themaximum value of TA in a cell is defined by the parameterMAXTA (Maximum Timing Advance).

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A cell must have exactly one BCCH, due to the fact that the BCCH carries essential information which must be known to the MS before call set-up

CELL DEFINITION• RLDEI: CELL=cell, CSYSTYPE=csystype, EXT;

• A cell can be defined in the BSC as internal or external.

• Internal cells are fully controlled by their own BSC

• External cells are not controlled by their own BSC.

• Certain data must be known to carry out a handover from a cell in its ownBSC to a cell, controlled by another BSC.

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RLDEC: CELL=cell, CGI=cgi, BSIC=bsic, BCCHNO=bcchno,NEWNAME=newname, AGBLK=agblk, MFRMS=mfrms,BCCHTYPE=bcchtype, FNOFFSET=fnoffset,XRANGE=xrange;

• CGI: Cell global identity. Expressed as MCC-MNC-LAC-CI.

• Cell Identity (CI): Each cell is assigned a CI.

• This number is unique per Location Area (LA) and is part of the Cell Global

• Identity (CGI). The CGI uniquely identifies a cell within GSM.

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The combination MCC-MNC-LAC is also known as the Location Area Identity (LAI).

It is important for the cellular network to know the location of a mobile since paging signals are distributed in one LA only.

A record in the MSC/VLR administrates a mobile location by means of the LAI.

When the MS moves from one LA to another, it sends a location-updating request to the MSC/VLR.

BSIC: Base Station Identity Code. It is transmitted on the SCH and is expressed as:

NCC = National Color Code of PLMN. Numeric 0 - 7.

BCC = Base Station Color code. Numeric 0 - 7.

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The purpose of the BSIC is to distinguish between cells with the same carrier frequency, but coming from different clusters.

In addition, it can be used to distinguish between cells from different operators on the border between two countries.

BCCHNO: Absolute RF channel number for BCCH. Numeral 1- 124 in GSM900, 512 - 885 in GSM1800, 512-810 in GSM1900.

If a cell is configured with at least two frequencies, it can besplit into two subcells - an overlaid subcell and an underlaid subcell.

This contributes to the network capacity being increased without adding new frequencies, but “stealing” some frequencies from the underlaid cluster.

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CHANNEL GROUPSRLDGI: CELL=cell, CHGR=chgr, SCTYPE=sctype;This command is used to specify channel groups for a cell orsubcell.

If a subcell structure is specified with the commandRLDSI, the parameter SCTYPE must be included in thiscommand.

CHGR: Channel group. Numeral 0-15. Maximum 16 channelgroups can be specified per cell.

SCTYPE: subcell typeUL= underlaidOL= overlaid

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RLCPC: CELL=cell, SCTYPE=sctype, MSTXPWR=mstxpwr,

BSPWRB=bspwrb, BSPWRT=bspwrt;

MSTXPWR: Maximum transmit power in dBm for an MS on aconnection.

BSPWRB: Base Station nominal output power in dBm, for theRF channel number, which has the BCCH.

BSPWRT: Base Station nominal output power in dBm, for theRF channels, which do not have the BCCH.

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FREQUENCY HOPPING DATA

RLCHC: CELL=cell, CHGR=chgr, HOP=hop, HSN=hsn;MAIO=maio;

This command is used to change the frequency hopping statusand hopping sequence number for a channel group. The CHGRparameter is mandatory, if channel groups other than 0 exist.The command is only valid for internal cells.

CHGR: Channel group. Numeral 0-15.

HOP: Frequency hopping status. On or off.

HSN: Hopping sequence number. Numeral 0-63.HSN= 0 is cyclic hoppingHSN= 1-63 identifies a pseudo-random sequence

MAIO: Mobile allocation index offsetNumeral 0 – 15, or DEFAULTMaximum 16 MAIOs per channel group. The MAIO(s) will form a list. All MAIOs in the list must be unique.

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CONFIGURATION FREQUENCY DATA

RLCFI: CELL=cell, CHGR=chgr, DCHNO=dchno;

If more frequencies than the BCCHNO must be added to the cell, these frequencies are defined separately.

The cell in question can be ACTIVE or HALTED

CHGR: Channel group. Numeral 0-15.

DCHNO: ARFCN (Absolute RF channel number). Numeric 1-124 in GSM900, 512 - 810 in GSM1800, 512 - 885 in GSM1900.

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MEASUREMENT FREQUENCIES

RLMFC:CELL=cell, MBCCHNO=mbcchno, LISTTYPE=listtype, MRNIC;

MBCCHNO: Is the Absolute RF Channel Number (ARFCN)for measurement on the BCCH. Numeric 1 - 124 in GSM 900,512 - 885 in GSM 1800

It represents the BCCH frequencies to be measured on by the MSs in the cell.

In dual mode systems, frequencies from both systems can be used simultaneously.

LISTTYPE: Indicates if the list of measurement frequencies is to be used by the MS for measurements in idle mode or for measurements in active mode.

MRNIC: Measurement Reports Not Interpreted Correctly. If MRNIC is used, the change of frequencies is executed immediately

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NEIGHBOR RELATIONS

• RLNRI: CELL=cell, CELLR=cellr, SINGLE;

• CELLR: Related cell. Max. seven characters.

• SINGLE: Defines the relationship between cells.

• The parameter SINGLE is only given if the relation is one-way from CELL - CELLR.

• This means that handover can be made from CELL to CELLR. • Default is mutual, which means that handovers are allowed in both directions.

• Thirty-two mutual neighbors can be defined for a cell.

• RLNRP:CELL=CELL,CELLR=ALL;

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CONNECTION OF CELL TO TRANSCEIVER GROUP

RXTCI: MO=mo, CELL=cell, CHGR=chgr;

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Cell State

HALTED TO ACTIVEThe defined cell configuration data is used for configuration.

Logical channels are created and the BCCH for the cell is activated.

System information messages are distributed to the MSs.

ACTIVE TO HALTEDOngoing calls are disconnected. All logical channels are deletedand the BCCH for the cell is de-activated.

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FAULTS

PERMANENT FAULT A managed object is classified as being permanently faulty, when fault situations have occurred and have been cleared a certain number of times within a certainperiod of time. Manual intervention is required to bring such equipment back into operation.

LOCAL MODEThe BTS equipment is in Local Mode or the BTS equipment has changed from Local to Remote Mode and a fault exists in the communication link between the BSC and the BTS. Communication between the BSC and the BTS is notpossible.

LOOP TEST FAILED Test of the traffic carrying capabilities of the TS has failed.

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OML FAULT There is a fault in the communication link between the BSC and BTS.

ABIS PATH UNAVAILABLE No transmission device exists between the BSC and BTS.

CON QUEUE CONGESTION At least one of the LAPD Concentrator concentration outlet queues has reached an unacceptable filling level.

TS SYNC FAULT Synchronization lost on uplink or downlink TRA or PCU channels