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GSM Basic (PowerPoint)

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					GSM Overview

         GSM System Overview
         GSM Abis
         GSM A-Interface
         GSM Signalling Procedures




coMPAss Product Training 14-15 May, Singapore

Slide 0
        GSM
   Global System
         for
Mobile Communication

(Groupe Spéciale Mobile)
                 Definition and
                 History
           BTS




coMPAss Product Training 14-15 May, Singapore

Slide 2
   Basic concept - 1
   GSM vs. fixed network Telephony

                                                                         fixed
                                                fixed                    location
          Local                                 medium     Telephone
          Exchange


                                                               SONOFON

                                                               M    N

                                                 Diffuse
                                                 Medium
                                                                         Variable
          Mobile
                                                                         Location
          Switching
          Centre                                              Mobile
                                                              Station

coMPAss Product Training 14-15 May, Singapore

Slide 3
   The evolution

                             UMTS / IMT-2000 (FPLMTS)

                               DCS 1800                       PCS 1900             GSM
                                                                                    CDMA
          DECT                     GSM at                       GSM at                  Digital
                                  1800 MHz                     1900 MHz                900 MHz
                                                                                                        Satellite
                                                                                                       (IRIDIUM)

                                                GSM
                                                 GSM                       GSM
                                                                           DAMPS
          CT2                                     Digital
                                                  Digital                    Digital
                                                                            (TDMA)
                                                 900 MHz
                                                 900 MHz                    900 MHz                Trunked
                                                                                                  mobile radio
                                                                                                   (TETRA)
                                 C-NET            NMT         TACS/ETACS    AMPS
   CT0, CT1                       Analog          Analog         Analog      Analog
                                 450 MHz        450/900 MHz     900 MHz     800 MHz
                                                                                                    Other systems
      Cordless                                      Mobile



coMPAss Product Training 14-15 May, Singapore

Slide 4
GSM Standards

         The GSM Standard is divided into phases (phase 1, phase 2 and phase 2+)
          all the phases has been finalized by ETSI.

         Many of the GSM networks in operation today are currently using the
          phase 2. However many of the GSM network operators are starting to
          implement phase 2+ (GPRS support).

         The ETSI GSM standard specification is around 5500 pages, and are
          divided into12 series.




coMPAss Product Training 14-15 May, Singapore

Slide 5
GSM Status

         Specification start-up:                     1980
         First network in operation:                 Jan. 1992 (Radiolinja, Finland)
         Forecast in 1995:
           – At the ITU's Telecom '95 event, were stated that we will reach 100 million
             subscribers Worldwide before the year 2000.
         September 1997:                       ~55 million subscribers.
                                                      ~1 new subscriber each second.
                                                      ~250 networks in 110 countries.
         July 1998:
           – More than15 months early then year 2000 the magic figure of 100 million
             subscribers was reached.
         Today :       Over 200 million subscribers.
                        369 networks in 137 countries.


coMPAss Product Training 14-15 May, Singapore

Slide 6
                        BTS
                                        GSM Services.



coMPAss Product Training 14-15 May, Singapore

Slide 7
Services
                                     Telephony
                                     Data services (up to 9600 b/s)
              BTS                    Fax group 3 (special modem)
                                     Short Message Service (SMS)
                                     Supplementary services, e.g.
                                        –   Call Forwarding
                                        –   Call Barring
                                        –   Call Waiting
                                        –   Three Party Service
                                        –   Advice of Charge




coMPAss Product Training 14-15 May, Singapore

Slide 8
GSM Features
                                    Integrated voice/data (ISDN)
                                    Improved performance
              BTS
                                    Improved security
                                      – Digital encryption
                                      – Authentication (IMSI)
                                      – TMSI assignment
                                    All types of Mobile Stations
                                    Automatic roaming
                                    Sophisticated radio functions
                                      – Discontinuous transmission - DTX
                                      – Frequency hopping



coMPAss Product Training 14-15 May, Singapore

Slide 9
 Services, phase 2 and 2+

                             Half-rate and enhanced full-rate speech
                             New supplementary services:
              BTS              –    Display of called and calling user's number
                               –    Multi-party conversations (up to 6 parties)
                               –    Closed user groups / virtual private networks
                               –    Call completion services (busy, no answer etc.)
                               –    Intelligent network services (CAMEL)
                               –    Roaming between GSM and DCS 1800 (PCS 1900)
                             High speed data services:
                               – High Speed Circuit Switched Data (HSCSD)
                               – General Packet Radio Service (GPRS)



coMPAss Product Training 14-15 May, Singapore

Slide 10
                 System
           BTS
                 architecture.




coMPAss Product Training 14-15 May, Singapore

Slide 11
 System Overview


  ISUP /              Public Switched                 ISUP /
   TUP              Telephone Network                  TUP                                                             Um
                          (PSTN
                            )



    Authen.                                      Equip. Id
              MAP                                                                                        BTS
    Centre                                       Register
     AUC                                           EIR
                                                                           Base                                        Mobile Station (MS)
                                                                          Station                            Base
       MAP                                      MAP                      Subsystem                       Transceiver
                 Home                Visitor            MAP                                               Base
                Location            Location                               (BSS)                            Station
                                                                                                       Transceiver
                                                                                                        Base
                Register            Register                                                                 BTS
                                                                                                         Station
                                                                                                    Transceiver
                                                                                      A-bis          Base
                  HLR                 VLR                                                          Base BTS
                                                                                                       Station
                                                                                                  Transceiver
 Mobile                                           Mobile                   Base
Switching                                        Switching                                       Base BTS
                                                                                                    Station
                                                                                                Transceiver
                                                                          Station
 Centre                                           Centre                                              BTS
                                                                                                  Station
                                                                                              Transceiver
                            MAP                                          Controller
  MSC                                              MSC         A-Inter                             BTS
                                                                                                Station
                           ISUP /                                          BSC
                                                                                                 BTS
                            TUP



                                                                                                                 2 Mbit/s PCM
                                                                                                                 Air Interface



coMPAss Product Training 14-15 May, Singapore

Slide 12
   System Building Blocks

                                                Visitor
                                     VLR        Location
                                                Register
                                                                                 SONOFON

                                                                                 M    N




                                                                    BTS
             HLR                    MSC                BSC

           Home                     Mobile            Base         Base
           Location                 Switching         Station      Transceiver
           Register                 Centre            Controller   Station




coMPAss Product Training 14-15 May, Singapore

Slide 13
HLR (Home Location register)
      “Home Base” of information regarding customers subscribing to a particular
       operators GSM network
      Keeps track of subscriber profile, conditions and whereabouts


                                       VLR

                                                                                    SONOFON

                                                                                    M    N




                                                                  BTS
               HLR                    MSC       BSC




coMPAss Product Training 14-15 May, Singapore

Slide 14
 HLR contains

                          Subscriber information:
                             –   IMSI (International Mobile Subscriber Identity)
              BTS
                             –   MSISDN (International Mobile Station ISDN Number)
                             –   MS Category (e.g. payphone)
                             –   Authentication vectors (RAND, SRES and Kc: AUC and
                                 SIM)
                             –   Allowed services (subscription data)

                          Mobile location information:
                             – VLR number
                             – (MSRN - Mobile Station Roaming Number)




coMPAss Product Training 14-15 May, Singapore

Slide 15
   VLR (Visitor Location register)
          Database with information about mobile users present/active in the network
           segment served by the MSC
          Handles true visitors as well as subscribers of the operator himself




                                      VLR

                                                                                        SONOFON

                                                                                        M    N




                                                                     BTS
              HLR                    MSC        BSC




coMPAss Product Training 14-15 May, Singapore

Slide 16
   VLR contains.

                           Subscriber information:
                              –    IMSI
                              –    TMSI - Temporary Mobile Subscriber Identity
              BTS             –    MS category
                              –    Authentication vectors
                              –    Allowed services

                           Mobile location information:
                              – MSRN - Mobile Station Roaming Number
                              – LAI - Location Area Identity




coMPAss Product Training 14-15 May, Singapore

Slide 17
BTS (Base Transceiver Station)

      Contains the radio transmitters and receivers (transceivers) covering a certain
       geographical area of the GSM network




                                      VLR

                                                                                     SONOFON

                                                                                     M    N




                                                                     BTS
              HLR                    MSC        BSC




coMPAss Product Training 14-15 May, Singapore

Slide 18
BSC (Base Station Controller)
          Controls a group of BTS’s in relation to power control and handover.
          The combination of a BSC and its BTS’s is called a Base Station Subsystem (BSS).
          The interface between the BTS and the is called the A-bis interface.



                                      VLR

                                                                                      SONOFON

                                                                                      M    N




                                                                      BTS
               HLR                   MSC         BSC




coMPAss Product Training 14-15 May, Singapore

Slide 19
  MSC (Mobile Switching Centre)
          Serves a number of BSS’s (Base Station Subsystem) via the A-interface.
          Responsible for call control (set-up, routing, control and termination of the calls)
          Management of inter-MSC handover and supplementary services, and for collecting
           charging/accounting information.
          Gateway to other to other GSM networks and public-switched networks)



                                      VLR

                                                                                      SONOFON

                                                                                      M    N




                                                                      BTS
              HLR                    MSC        BSC




coMPAss Product Training 14-15 May, Singapore

Slide 20
   AUC - Authentication Centre

                        Contains the individual subscriber-identification key
                         (also contained in the SIM), and provides the subscriber
                         data to the HLR and VLR used for authentication and
              BTS        encryption of calls.



                                                AUC




                                                 HLR




coMPAss Product Training 14-15 May, Singapore

Slide 21
   EIR - Equipment Identity Registration.
                           Stores information about mobile stations in use and may
                            block calls from a MS if the MS is stolen, not type-
                            approved or has faults which may disturb the network.
                           Each MS is identified by a unique International Mobile
              BTS           Station Equipment Identity (IMEI)




                                                    EIR



                                                    MSC



coMPAss Product Training 14-15 May, Singapore

Slide 22
   (MS) Mobile Station



                                          Power:
                                             - Class 1:   20 W    Vehicle/
                                             - Class 2:    8W     portable
                                             - Class 3:    5W     Hand-held
                                             - Class 4:    2W     Hand-held
                                             - Class 5:   0.8 W   Hand-held




coMPAss Product Training 14-15 May, Singapore

Slide 23
                 Functional model.
           BTS




coMPAss Product Training 14-15 May, Singapore

Slide 24
 System Overview


  ISUP /              Public Switched                 ISUP /
   TUP              Telephone Network                  TUP                                                             Um
                          (PSTN
                            )



    Authen.                                      Equip. Id
              MAP                                                                                        BTS
    Centre                                       Register
     AUC                                           EIR
                                                                           Base                                        Mobile Station (MS)
                                                                          Station                            Base
       MAP                                      MAP                      Subsystem                       Transceiver
                 Home                Visitor            MAP                                               Base
                Location            Location                               (BSS)                            Station
                                                                                                       Transceiver
                                                                                                        Base
                Register            Register                                                                 BTS
                                                                                                         Station
                                                                                                    Transceiver
                                                                                      A-bis          Base
                  HLR                 VLR                                                          Base BTS
                                                                                                       Station
                                                                                                  Transceiver
 Mobile                                           Mobile                   Base
Switching                                        Switching                                       Base BTS
                                                                                                    Station
                                                                                                Transceiver
                                                                          Station
 Centre                                           Centre                                              BTS
                                                                                                  Station
                                                                                              Transceiver
                            MAP                                          Controller
  MSC                                              MSC         A-Inter                             BTS
                                                                                                Station
                           ISUP /                                          BSC
                                                                                                 BTS
                            TUP



                                                                                                                 2 Mbit/s PCM
                                                                                                                 Air Interface



coMPAss Product Training 14-15 May, Singapore

Slide 25
A functional model

    Call Management (CM)
                                                                          VLR
         – Call Control (CC)
         – SMS
         – Non Call-related SS
    Mobility Management (MM)                       SONOFON

                                                    M    N



                                                                          MSC
                                                                    BSC         HLR
    Radio Resource                                           BTS
     Management (RR)

                                               CM

                                               MM

                                               RR



    coMPAss Product Training 14-15 May, Singapore

    Slide 26
   GSM Protocol Architecture
                              MS                           BTS                                    BSC                                MSC

                              CM                    (CM)          (CM)                     (CM)        DTAP
                                                                                                                        CM
                                                                                           (MM)                                              I
                              MM                    (MM)          (MM)                               (CM+MM)
           Layer 3                                                                                                           MM              S
                                                                                                                                         MAP
                                                                                                                                             U
  BTS                                               (RR)          (RR)                                                                       P
                                                                                                                         BSSMAP        TCAP
                              RR                                                          RR            BSSMAP

                                              RR'                                     BTSM              SCCP                  SCCP     SCCP
                                                                    BTSM
                         Sig. layer 2         Sig. layer 2    Sig. layer 2           Sig. layer 2
           Layer 2
                         (LAPDm)              (LAPDm)         (LAPD)                 (LAPD)
                                                                                                        MTP                   MTP          MTP
           Layer 1       Layer 1 (air)                                               Sig. layer 1
                                              Layer 1 (air)   Sig. layer 1


                                    Um Interface                         Abis Interface                        A Interface                       Inter-MSC


                            DTAP - Direct Transfer Application Part                             SCCP - Signalling Connection Control Part
                            BSSMAP - BSS Management Application Part                            MAP - Mobile Application Part
                            CM - Call Management                                                TCAP - Transaction Capability Application Part
                            MM - Mobile Management                                              ISUP - ISDN User Part
                            RR - Radio Resource Management                                      MTP - Message Transfer Part
                            BTSM - BTS Management




coMPAss Product Training 14-15 May, Singapore

Slide 27
  Layer 3 Network Layer

                         The Network layer contains the signalling procedures and is
                          divided into:
                            – CM - Call Management.
              BTS
                            – MM - Mobility Management.
                            – RR - Radio Resource Management.




coMPAss Product Training 14-15 May, Singapore

Slide 28
  Call Management (CM)

                          Call Management takes care of the ordinary call-control
                           procedure:
              BTS            – Establishment and release of calls, as well as access to services and
                                 facilities.
                          CM is divided into:
                             – Call Control (CC), short messages services (SMS).
                             – Non-call-related supplementary services (SS).




coMPAss Product Training 14-15 May, Singapore

Slide 29
   Mobility Management (MM)


                          Mobility Management handles roaming and authentication
                           procedure.
              BTS




coMPAss Product Training 14-15 May, Singapore

Slide 30
     Radio Resource Management (RR)

                                    Radio Resource Management comprise:
                                      –    Paging.
              BTS                     –    Radio-channel access.
                                      –    Ciphering.
                                      –    Handover.
                                      –    Radio-signal control
                                      –    Radio-signal measurement




coMPAss Product Training 14-15 May, Singapore

Slide 31
           Layer 2,
           Data Link Protocol.

                          The Data Link Protocol is used at the Um and A-bis interface,
                           the Data Link Protocol is based on LAPD (ISDN D-channel
              BTS
                           layer 2 protocol).

                          On the A-Interface MTP and SCCP are used as signalling-
                           transport function.

                          On the inter-MSC interface, MTP is used for ISUP, TUP and
                           MTP + SCCP + TCAP is used for MAP.




coMPAss Product Training 14-15 May, Singapore

Slide 32
           Layer 1
           Physical Link

                          Physical Link of the signalling is time slots in the radio carriers
                           (TS0-7) and digital PCM (E1/T1)lines.
              BTS




coMPAss Product Training 14-15 May, Singapore

Slide 33
                 Radio (Um)
           BTS
                 Interface
                                                      Um




                                                BTS




coMPAss Product Training 14-15 May, Singapore

Slide 34
  The System

  ISUP /              Public Switched                ISUP /
   TUP              Telephone Network                 TUP                                                              Um
                          (PSTN
                            )



    Authen.                                      Equip. Id
              MAP                                                                                        BTS
    Centre                                       Register
     AUC                                           EIR
                                                                          Base                                         Mobile Station (MS)
                                                                         Station                             Base
       MAP                                     MAP                      Subsystem                        Transceiver
                 Home                Visitor           MAP                                                Base
                Location            Location                              (BSS)                             Station
                                                                                                       Transceiver
                                                                                                        Base
                Register            Register                                                                 BTS
                                                                                                         Station
                                                                                                    Transceiver
                                                                                      A-bis          Base
                  HLR                 VLR                                                          Base BTS
                                                                                                       Station
                                                                                                  Transceiver
 Mobile                                           Mobile
                                                 Switching                Base                   Base BTS
                                                                                                    Station
                                                                                                Transceiver
Switching                                                                 Station
 Centre                                           Centre                                              BTS
                                                                                                  Station
                                                                                              Transceiver
                            MAP                                          Controller
  MSC                                              MSC        A-Inter     BSC                      BTS
                                                                                                Station
                           ISUP /                                                                BTS
                            TUP



                                                                                                                 2 Mbit/s PCM
                                                                                                                 Air Interface




 coMPAss Product Training 14-15 May, Singapore

 Slide 35
  Protocol Architecture
                        MS                           BTS                                    BSC                                MSC

                        CM                    (CM)          (CM)                     (CM)        DTAP
                                                                                                                  CM
                                                                                     (MM)                                              I
                        MM                    (MM)          (MM)                               (CM+MM)                 MM              S
                                                                                                                                   MAP
                                                                                                                                       U
  BTS                                         (RR)          (RR)                                                                       P
                                                                                                                   BSSMAP        TCAP
                        RR                                                          RR            BSSMAP

                                         RR                                     BTSM              SCCP                  SCCP     SCCP
                                                              BTSM
                   Sig. layer 2         Sig. layer 2    Sig. layer 2           Sig. layer 2
                   (LAPDm)              (LAPDm)         (LAPD)                 (LAPD)
                                                                                                  MTP                   MTP          MTP
                   Layer 1 (air)        Layer 1 (air)   Sig. layer 1           Sig. layer 1


                              Um Interface                         Abis Interface                        A Interface                       Inter-MSC


                      DTAP - Direct Transfer Application Part                             SCCP - Signalling Connection Control Part
                      BSSMAP - BSS Management Application Part                            MAP - Mobile Application Part
                      CM - Call Management                                                TCAP - Transaction Capability Application Part
                      MM - Mobile Management                                              ISUP - ISDN User Part
                      RR - Radio Resource Management                                      MTP - Message Transfer Part
                      BTSM - BTS Management




coMPAss Product Training 14-15 May, Singapore

Slide 36
    GSM 900 Radio (Um) Interface
    Physical Channels
    In GSM approx. 1000 radio channels has been assigned in the 900
     MHz band. More precisely:
       – 890 - 915 MHz “Uplink”
       – 935 - 960 MHz “Downlink”
    A combination of frequency and time division is used.
       – 124 carriers
       – Carrier spacing is 200 kHz
       – 8 timeslots per carrier

                                 SONOFON

                                  M    N




                                                                       BTS


coMPAss Product Training 14-15 May, Singapore

Slide 37
    DCS-1800 Radio (Um) Interface
    Physical Channels
    In GSM 1800 2992 radio channels has been assigned in the 1800 MHz
     band. More precisely:
       – 1710 - 1785 MHz “Uplink”
       – 1805 - 1880 MHz “Downlink”
    A combination of frequency and time division is used.
       – 374 carriers
       – Carrier spacing is 200 kHz
       – 8 timeslots per carrier


                                  SONOFON

                                  M     N




                                                                         BTS


coMPAss Product Training 14-15 May, Singapore

Slide 38
               TDMA Frame Structure

                               13 kbit/s user data
                                                                           4.615 msec


                          TDMA Frame                    0     1        2   3    4       5   6        7

                                                                           0.577
           BTS                                                             msec

                                                    3             57       1   26   1       57           3   8.25
                          Time Slot                TB       Coded Data C       TS   C   Coded Data TB GP

                                                   Duration of 1 bit: 3.692 usec

                               TS          : Tail bit
                               TS          : Training Sequence (setting up the receiver equaliser)
                               GP          : Guard Period
                               C           : Control bit



coMPAss Product Training 14-15 May, Singapore

Slide 39
 Physical Channels

                                                                                Traffic channels
                                                                                showing three timeslot
                                                                                delays between the
                           TS7                    TS3                           down and up links.
                              TS6                    TS2
                                TS 5                   TS 1
                                  TS 4                    TS 0
                              BTS    TS 3
                                       TS2
                                                            TS 7
                                                               TS6
                                          TS                     TS
                                          0 TS7                  5 TS4
                                              TS6                    TS3
             Control Channels                   TS 5                   TS 2
                                                  TS 4                   TS1
                                                     TS 3                   TS 0
             Control Channels                          TS2                    TS7
                                                          TS                     TS
             Traffic Channels                             1 TS0                  6 TS5
                                                                Downlink                 Uplink

                 Eight TS, or eight physical
                 channels compromise a FRAME




coMPAss Product Training 14-15 May, Singapore

Slide 40
Radio (Um) Interface burst modulation
structure Tail Information Training Information Tail Guard

                Normal                                                                         8.25
                              3    57+1 (TCH/FACCH)      26       57+ 1 (TCH/FACCH)       3
                burst

                            Tail       Training       Information Tail         Guard
                Access                                                            68,25
                              7            41            36          3
                burst

                            Tail Information           Training           Information Tail Guard
                SCH                                                                            8.25
                              3         39                64                 39            2
                burst

                            Tail                       Information                        Tail Guard
                FCCH                                                                           8.25
                              3                            142                            3
                burst


                         Not illustrated is the “dummy” burst which has the same structure as the “Normal”
                         burst. The dummy burst is sent when no information is transmitted on a TCH


 coMPAss Product Training 14-15 May, Singapore

 Slide 41
   Radio (Um) Interface Normal burst
                            Tail       Information    Training      Information      Tail Guard

                Normal                                                                     8.25
                             3     57+1 (TCH/FACCH)      26      57+ 1 (TCH/FACCH)    3
                burst

          For the “Normal” burst, one of the 58 information bits on each side of
           the training sequence is a flag bit indicating whether the burst is a TCH -
           traffic channel (0) or for a FACCH - fast associated control channel (1).
          The burst is converted to FACCH when signalling is required after a
           TCH has been allocated.

            – Note: Each “Normal” burst (TDMA) time slot period consist of 156.25 bits (equal to
               33.9 kbit/s per time slot or 270.8 kbit/s per frame carrier), of which 144 (2*57) bits are
               coded data including forward error correction. All information is transferred in
               blocks of 456bits divided into four time slot periods (456 = 4*2*57). The maximum net
               bit rate is 13 kbit/s (Excluding the error correction)




coMPAss Product Training 14-15 May, Singapore

Slide 42
     Radio (Um) Interface Access burst

                            Tail       Training   Information Tail      Guard
                Access                                                  68,25
                             7             41        36        3
                burst




      The “access” burst is a shortened burst used by the mobile station when it
       first access a cell.
      Its short length guarantees it will arrive within the correct time slot at the
       BTS receiver if the mobile station is no greater than 35km from the BTS.
           – 68,25 bits * 3,7gs (1 bit) = 251gs ~ (75Km / 2) = 37,5Km




coMPAss Product Training 14-15 May, Singapore

Slide 43
   Time Division Multiple Access burst

                                                             Downstream:
                                                              – A series of bits intended for different users,
                                                                  who must select only the one intended for
                                                                  him and filter out the rest
                                                             Upstream:
                                                              – Individual bits from each of the users
                                                                  arrive at the BTS
    BTS                                                       –   Strict timing of when the MS should
                                                                  transmit is required to avoid collisions at
Wrong Uplink Timing                                               the BTS

                                                                                   SONOFON

                                                                                   M    N

                                                SONOFON

                                                M    N




                                                                                                SONOFON

                                                                                                 M   N




                                                                         SONOFON

                                                                         M    N




coMPAss Product Training 14-15 May, Singapore

Slide 44
Timing advance (Access burst)
                1 Km                             15 Km                                  30 Km


                      TS             TS                            TS             TS                        TS             TS




       BTS
                                                                                                                 SONOFON
                           SONOFON                                      SONOFON
                                                                                                                 M    N
                           M    N                                        M   N




               The transmitted radio burst from BTS must travel whatever the distance is to the mobile station , and
                then transmitted burst from the mobile station (three burst later) must travel back the same distance.
                By measuring the time between the last bit in the access burst and the last bit in the TS the mobile then
                know the distance to the BTS and will adjust its Timing advance to compensate for the distance.

                                                                    Access
                                                                    burst  Timing advance

                                                                                   TS

 coMPAss Product Training 14-15 May, Singapore

 Slide 45
  Mobile Station
  Timing advance Measurement Report
                  Message Type                       : 3Fh = Immediate assignment
                 --- Channel description ---
                      Time slot number               : .....001
                      Channel type and TDMA offset   : 01011... = SDCCH/8 + SACCH/C8 or CBCH (SACCH/8)
                      Training Sequence Code         : 011.....
                      Hopping channel                : ...0.... = Single RF channel
                      spare                          : ....00..
                      Absolute RF Channel Number     : 720
                      --- Request reference ---                         Timing advance = 2
                      Random access information      :4
                      T1                             :7                 The mobile station is 1km
                      T3                             : 19
                      T2                             :7
                                                                        from the BTS.
                      --- Timing advance ---
                      Timing advance value           : ..000010
                      Spare                          : 00......




coMPAss Product Training 14-15 May, Singapore

Slide 46
   SCH burst
                            Tail Information    Training   Information Tail Guard
               SCH                                                          8.25
                             3          39        64          39        2
               burst




      The SCH burst is the synchronization channel burst which carries the the
       BSIC - Base Station Identity Code and the FN - Frame Number.
      As this is the first burst decoded by the mobile station it has an extended
       training sequence.




coMPAss Product Training 14-15 May, Singapore

Slide 47
   FCCH burst
                            Tail                Information      Tail Guard
               FCCH                                                   8.25
                             3                     142            3
               burst




           The FCCH burst is the frequency correction channel burst which is
            modulated with zero




coMPAss Product Training 14-15 May, Singapore

Slide 48
   Radio (Um) Interface Logical Channels
                                 Traffic channels (TCH):
                                     – Carrying Voice/data
                                     – Bm: 13 kbit/s user data
       BTS
                                     – Lm: Half rate (6,5 kbit/s)

                                 Common control channels (CCCH):
                                     – Channels that all Mobile Stations can share

                                 Dedicated control channels (DCCH):
                                     – Control channels for individual Mobile Stations




coMPAss Product Training 14-15 May, Singapore

Slide 49
Radio (Um) Interface Common Control
Channels
                                Broadcast: BCCH
                                   – Carry system info intended for everybody, e.g. Location Area
                                       Identity
        BTS                     Paging: PCH
                                   – To request a specific Mobile User to react/reply, e.g. when
                                       there is a call for him
                                Random Access: RACH
                                   – Used by the Mobile Station to initiate contact with the
                                       network, e.g. when trying to start a call
                                Access Granted: AGCH
                                   – Used to respond to the RACH to inform that the Mobile is
                                       now being allowed to access the network



 coMPAss Product Training 14-15 May, Singapore

 Slide 50
Radio (Um) Interface Dedicated Control
Channels

                            Stand-alone Dedicated : SDCCH
                                – Used for settling practicalities such as roaming,
        BTS
                                     authentication, encryption and call control before allocating
                                     the traffic channel
                            Slow Associated: SACCH
                                – Associated to a TCH
                                – Used together with the Traffic Channel to deal with control
                                     and measurement of radio signals
                            Fast Associated: FACCH
                                – Large bandwidth version of the SACCH
                                – Used for sudden control action such as handovers
                                – Implemented a robbed bits in a TCH


 coMPAss Product Training 14-15 May, Singapore

 Slide 51
         Hyper-, Super- and Multiframes
                                          1 hyperframe = 2048 superframes (3h 28min 53s 760ms)
         0       1       2        3           4           5            6                                                                2042         2043      2044   2045     2046    2047
                              1 superframe = 26 (51-frames) or 51 (26-frames) multiframes
                                                        (6.12s)

                              0       1           2       3       4        5    6    7              18       19       20      21   22       23       24       25

                             0 1 2 3 4 5 6                                                                                              45 46 47 48 49 50



    1 (26-frame) multiframe = 26 TDMA frames (120ms)
0    1       2       3   4   5        6           7               18       19   20   21   22       23       24       25




             0       1   2    3           4           5       6        7

    1 TDMA frame = 8 timeslots (4.615 ms) (51-frame) multiframe = 51 TDMA frames (235.38 ms)
                                        1
                                                                            0 1 2 3 4 5 6                                                                                    45 46 47 48 49 50


                                                                                               0        1        2        3    4        5        6        7

                                                                                     1 TDMA frame = 8 timeslots (4.615 ms)
     coMPAss Product Training 14-15 May, Singapore

     Slide 52
     TDMA Frame with 1 combined CCH and 7
     TCH
Downlink and Uplink                           Cyklus: 1 TCH multiframe = 26 TDMA frames = 120 ms


               Bm Bm Bm Bm Bm Bm Bm Bm Bm Bm Bm Bm SA Bm Bm Bm Bm Bm Bm Bm Bm Bm Bm Bm Bm                                           -


                                                                   4.615 ms

    TDMA Frame (8 timeslots)                      0    1       2     3    4     5    6      7

Downlink:
                                                  Cyklus: 1 CCH multiframe = 51 TDMA frames = 235.38 ms


   F S       BCCH   PCH/AGCH F S PCH/AGCH PCH/AGCH F S              SDCCH/1   SDCCH/2 F S   SDCCH/3    SDCCH/4 F S SACCH/1   SACCH/2 -
   F S       BCCH   PCH/AGCH F S PCH/AGCH PCH/AGCH F S              SDCCH/1   SDCCH/2 F S   SDCCH/3    SDCCH/4 F S SACCH/3   SACCH/4 -

Uplink:                       F = Frequency correction burst                             S = Synchronisation burst

   R R SACCH/1      SACCH/2 R R R R R R R R R R R R R R R R R R R R R R R SDCCH/1                        SDCCH/2 R R SDCCH/3   SDCCH/4
   R R SACCH/3      SACCH/4 R R R R R R R R R R R R R R R R R R R R R R R SDCCH/1                        SDCCH/2 R R SDCCH/3   SDCCH/4
   R = RACH




  coMPAss Product Training 14-15 May, Singapore

  Slide 53
    Cell Structure
                                                            Omni-directional BTS
                       F1                        F2
                                                                    Safety distance
                 BTS                       BTS




                        R                             5xR
    F3                                                                                     F4
                                    F4
                                                                                                     BTS



                              BTS                           To avoid interference between two cells using the same frequency,
               F5                        F6                 a safety distance of about 5 times the cell radius is required.
                                                            A BTS may cover one cell (Omni-directional) or several cells
                                                            (typical three directional cells).
                                                            Each cell may be served by on or more TRXs depending on the
                                                            required capacity.

           3-directional BTS                                Note: each TRX controls one carrier with eight TS.




coMPAss Product Training 14-15 May, Singapore

Slide 54
   Radio (Um) Interface Neighbour Cells

                                      Mobile station in IDLE mode
                                         – Besides listening to the BCCH and the PCH the mobile
                                                station is measuring for neighbour cells.
                                      Mobile station in active mode
                                         – In active mode the mobile station is using the time
       BTS


                                                between the down and uplink TS (three TS 2ms) to do
                                                neighbour cell measuring.
                                      The mobile station can measure up to 31 neighbour
                                       cells.
                                         – In practice the mobile station measures up to 12
                                                neighbour cells.
                                         –      Very often only three or four cells are measured.




coMPAss Product Training 14-15 May, Singapore

Slide 55
  Mobile Station
  Neighbour Cells Measurement Report
                      --- MEAS REP ---
                          --- MEAS RES ---
                     NO NCELL M : 100b = 4 neighbour cell measurement result
                          RXL NCEL 1 : 36 = minimum received signal level = -75 dBm to -74 dBm
                          BCCH NCEL1 : 1
                          BSIC NCEL1 : 57
                          RXL NCEL 2 : 24 = minimum received signal level = -87 dBm to -86 dBm
                          BCCH NCEL2 : 12
                          BSIC NCEL2 : 63
                          RXL NCEL 3 : 23 = minimum received signal level = -88 dBm to -87 dBm
                          BCCH NCEL3 : 7
                          BSIC NCEL3 : 59
                          RXL NCEL 4 : 16 = minimum received signal level = -95 dBm to -94 dBm
                          BCCH NCEL4 : 2
                          BSIC NCEL4 : 56
                          RXL NCEL 5 : 0 = minimum received signal level less than -110 dBm
                          BCCH NCEL5 : 0
                          BSIC NCEL5 : 0
                          RXL NCEL 6 : 0 = minimum received signal level less than -110 dBm
                          BCCH NCEL6 : 0
                          BSIC NCEL6 : 0




coMPAss Product Training 14-15 May, Singapore

Slide 56
   (MS) Mobile Station SIM Card
                                    IMSI
                                      – - International Mobile subscriber Number
                                    MSISDN
                                      – - Mobile Station ISDN Number
                                    Latest BCCH List
                                      – The latest BCCH used last time the mobile station was
                                           connected to the network.
                                    Preferred Network List.
                                    Forbidden Network List.
                                    KI
                                      – The Key identifier refers to an authentication key for the
                                           mobile subscriber.




coMPAss Product Training 14-15 May, Singapore

Slide 57
       A-bis
           BTS




coMPAss Product Training 14-15 May, Singapore

Slide 58
  The System.

  ISUP /              Public Switched                ISUP /
   TUP              Telephone Network                 TUP                                                             Um
                          (PSTN
                            )



    Authen.                                      Equip. Id
              MAP                                                                                       BTS
    Centre                                       Register
     AUC                                           EIR
                                                                          Base                                        Mobile Station (MS)
                                                                         Station                            Base
       MAP                                     MAP                      Subsystem                       Transceiver
                 Home                Visitor           MAP                                               Base
                Location            Location                              (BSS)                            Station
                                                                                                      Transceiver
                                                                                                       Base
                Register            Register                                                                BTS
                                                                                                        Station
                                                                                                   Transceiver
                                                                                     A-bis          Base
                  HLR                 VLR                                                         Base BTS
                                                                                                      Station
                                                                                                 Transceiver
 Mobile                                           Mobile                  Base
Switching                                        Switching                                      Base BTS
                                                                                                   Station
                                                                                               Transceiver
                                                                         Station
 Centre                                           Centre                                             BTS
                                                                                                 Station
                                                                                             Transceiver
                            MAP                                         Controller
  MSC                                              MSC        A-Inter                             BTS
                                                                                               Station
                           ISUP /                                         BSC
                                                                                                BTS
                            TUP



                                                                                                                2 Mbit/s PCM
                                                                                                                Air Interface




 coMPAss Product Training 14-15 May, Singapore

 Slide 59
   Protocol Architecture
                        MS                           BTS                                    BSC                                MSC

                        CM                    (CM)          (CM)                     (CM)        DTAP
                                                                                                                  CM
                                                                                     (MM)                                              I
                        MM                    (MM)          (MM)                               (CM+MM)                 MM              S
                                                                                                                                   MAP
                                                                                                                                       U
  BTS                                         (RR)          (RR)                                                                       P
                                                                                                                   BSSMAP        TCAP
                        RR                                                          RR            BSSMAP

                                        RR'                                     BTSM              SCCP                  SCCP     SCCP
                                                              BTSM
                   Sig. layer 2         Sig. layer 2    Sig. layer 2           Sig. layer 2
                   (LAPDm)              (LAPDm)         (LAPD)                 (LAPD)
                                                                                                  MTP                   MTP          MTP
                   Layer 1 (air)        Layer 1 (air)   Sig. layer 1           Sig. layer 1


                              Um Interface                         Abis Interface                        A Interface                       Inter-MSC


                      DTAP - Direct Transfer Application Part                             SCCP - Signalling Connection Control Part
                      BSSMAP - BSS Management Application Part                            MAP - Mobile Application Part
                      CM - Call Management                                                TCAP - Transaction Capability Application Part
                      MM - Mobile Management                                              ISUP - ISDN User Part
                      RR - Radio Resource Management                                      MTP - Message Transfer Part
                      BTSM - BTS Management




coMPAss Product Training 14-15 May, Singapore

Slide 60
   A-bis (A) Layer 1 Structures
                                            64 kbit/s signalling channels


                    TS 0          TS 1          TS 2        TS 3       TS 4         TS 5   ----   TS 31

                  TS = 64 kbit/s timeslot

           BTS
                                                       16 kbit/s traffic channels


           One 2Mbit/s line may cover several BTSs. This means that
           normally several time slots in the same PCM frame are used
           as signalling channels.
                 Three time slots divided into one 64Kbit/s signalling channel and eight 16Kbit/s
                 traffic channels are sufficient to cover one TRX, giving up to 10 TRXs and 10
                 signaling channels per 2 Mbit/s.
                 In practice , the configuration of the transmission lines depends on the actual
                 network structure and the GSM equipment used.

coMPAss Product Training 14-15 May, Singapore

Slide 61
   A-bis Layer 2 Structure
                      Flag        Address          Control      Information     CRC          Flag
                    01111110      16 Bits        8 or 16 Bits     N - Bits     16 Bits     01111110


                                                                   SAPI -Service Access Point Identifier
                                                                   TEI - Terminal End Point Identifier
           BTS             SAPI           C/R   EA 0               C/R -Command / Response bit
                              TEI               EA 1               EA -Address Extension bit
                                                                          0 = Extend 1 = Final




       SAPI value                     Related entity              TEI value                 User type
           0          Radio signalling                              0-63        For fixed TRX addresses
           1          Reserved for packet mode /Q.931              64-126       For additional TRX addresses
          16          Reserved for packet mode /X.25
          62          Operation and maintenance                         Not used in GSM
          63          Layer 2 management
       All others     Reserved for future standardisation               Vendor-specific




coMPAss Product Training 14-15 May, Singapore

Slide 62
   A-bis Layer 2 Control Field

                               OCTET 1 OCTET 2 + 3                  OCTET 4 ( + 5 )                                   OCTET N
                                 Flag              Address              Control          Information     CRC            Flag
                               01111110            16 Bits           8 or 16 Bits          N - Bits     16 Bits       01111110


   BTS
            Control field bits                                                        Control field bits
                               8    7     6    5     4    3     2    1                                   8   7    6   5   4   3   2    1
              ( modulo 8 )                                                             ( modulo 128 )
                                                                                                                      N(S)            0     OCTET 4
              I format             N(R)       P          N(S)       0    OCTET 4        I format                                                  5
                                                                                                                      N(R)            P
                                                                                                        X    X    X   X S S       0   1     OCTET 4
              S format             N(R)       P/F S       S   0     1    OCTET 4        S format
                                                                                                                      N(R)            P/F         5

              U format        M M M P/F M M 1                       1    OCTET 4        U format        M M M P/F M M 1               1     OCTET 4


           I forma - Information transfer format                                      N(S) - Transmitter send sequence number
                  Used for information transfer between layer 3                       N(R) - Transmitter receive sequence number
                  entities                                                            S -Supervisory function bit
           S format - Supervisory format                                              M -Modifier function bit
                  Used for control functions                                          P/F - Poll bit when issued as a command Poll bit
           U format - Unnumbered format                                               when issued as a command Final bit when issued as
                  Used for additional control functions and                           a response
                  information transfer                                                X - Reserved and set to 0




coMPAss Product Training 14-15 May, Singapore

Slide 63
   A-bis Information Elements, part 1
 - Channel number                              (Indicates channel on radio interface)
 - Link identifier                        (Signalling link and SAPI used on radio interface)
 - Activation type                        (Intra-cell, inter-cell or additional assignment CHAN ACTIV)
 - BS power                               (BTS/TRX power level)
 - Channel identification                      (Description of channels allocated to MS)
 - Channel mode                           (Indicates discontinuous transmission and channel type, e.g.
 speech)
 - Encryption information                 (Encryption algorithm and key)
 - Frame number                           (On radio interface, modulo 42432)
 - Handover reference                     (Identical to handover reference in RR information elements)
 - L1 information                         (MS power level and timing advance)
 - L3 information                         (Contains transparent RR, MM or CM message)
 - MS identity                                 (IMSI or TMSI)
 - MS power                               (MS power level)
 - Paging group                           (Identifies MS paging group)
 - Paging load                                 (Load on paging channel, PCH)
 - Physical context                            (Not specified)
 - Access delay                           (Delay of MS access burst at random access or handover)
 - RACH load                                   (Load of random access channel, RACH)
 - Request reference                      (Random ref. in RR Channel Request message)


coMPAss Product Training 14-15 May, Singapore

Slide 64
   A-bis Information Elements, part 2
 - Release mode          (Normal release or local end release)
 - Resource information       (Interference level for idle TRX channels)
 - RLM cause                  (Indicates protocol error on radio link layer)
 - Starting time         (Expressed as Frame Number modulo 42432)
 - Timing advance             (To be used by MS in subsequent communications)
 - Uplink measurements        (Radio signal measurement results from TRX)
 - Cause                      (Reason for event/failure)
 - Measurement result num     (For a radio channel; set to 0 at activation)
 - Message identifier    (In ERROR REPORT message: Message type of errored
 message)
 - Message indicator     (In ERROR REPORT message: Copy of errored message
 follows)
 - System info type           (Type of RR System Information message)
 - MS power parameters        (Limits set by BSC for BTS control of MS power)
 - BS power parameters        (Limits set by BSC for BTS control of TRX power)
 - Preprocessing param.       (For preproc. of radio measurement data in BTS)
 - Preprocessed
     measurements        (Preprocessed radio measurement data)
 - Immediate assign info      (Conveys complete RR Immediate Assign msg.)
 - SMSCB information     (SMS-message to be broadcasted in a radio cell)


coMPAss Product Training 14-15 May, Singapore

Slide 65
           A-Interface
           BTS




coMPAss Product Training 14-15 May, Singapore

Slide 66
  The System.

  ISUP /              Public Switched                ISUP /
   TUP              Telephone Network                 TUP                                                             Um
                          (PSTN
                            )



    Authen.                                      Equip. Id
              MAP                                                                                       BTS
    Centre                                       Register
     AUC                                           EIR
                                                                          Base                                        Mobile Station (MS)
                                                                         Station                            Base
       MAP                                     MAP                      Subsystem                       Transceiver
                 Home                Visitor           MAP                                               Base
                Location            Location                              (BSS)                            Station
                                                                                                      Transceiver
                                                                                                       Base
                Register            Register                                                                BTS
                                                                                                        Station
                                                                                                   Transceiver
                                                                                     A-bis          Base
                  HLR                 VLR                                                         Base BTS
                                                                                                      Station
                                                                                                 Transceiver
 Mobile                                           Mobile                  Base
Switching                                        Switching                                      Base BTS
                                                                                                   Station
                                                                                               Transceiver
                                                                         Station
 Centre                                           Centre                                             BTS
                                                                                                 Station
                                                                                             Transceiver
                            MAP                                         Controller
  MSC                                              MSC        A-Inter                             BTS
                                                                                               Station
                           ISUP /                                         BSC
                                                                                                BTS
                            TUP



                                                                                                                2 Mbit/s PCM
                                                                                                                Air Interface




 coMPAss Product Training 14-15 May, Singapore

 Slide 67
   Protocol Architecture
                        MS                           BTS                                    BSC                                MSC

                        CM                    (CM)          (CM)                     (CM)        DTAP
                                                                                                                  CM
                                                                                     (MM)                                              I
                        MM                    (MM)          (MM)                               (CM+MM)                 MM              S
                                                                                                                                   MAP
                                                                                                                                       U
  BTS                                         (RR)          (RR)                                                                       P
                                                                                                                   BSSMAP        TCAP
                        RR                                                          RR            BSSMAP

                                        RR'                                     BTSM              SCCP                  SCCP     SCCP
                                                              BTSM
                   Sig. layer 2         Sig. layer 2    Sig. layer 2           Sig. layer 2
                   (LAPDm)              (LAPDm)         (LAPD)                 (LAPD)
                                                                                                  MTP                   MTP          MTP
                   Layer 1 (air)        Layer 1 (air)   Sig. layer 1           Sig. layer 1


                              Um Interface                         Abis Interface                        A Interface                       Inter-MSC


                      DTAP - Direct Transfer Application Part                             SCCP - Signalling Connection Control Part
                      BSSMAP - BSS Management Application Part                            MAP - Mobile Application Part
                      CM - Call Management                                                TCAP - Transaction Capability Application Part
                      MM - Mobile Management                                              ISUP - ISDN User Part
                      RR - Radio Resource Management                                      MTP - Message Transfer Part
                      BTSM - BTS Management




coMPAss Product Training 14-15 May, Singapore

Slide 68
A-Interface

                       Based on System7 MTP and SCCP
           BTS         Uses Base Station Subsystem Application Part (BSSAP)
                          – BSS Management Application Part (BSSMAP)
                                 • Radio Resource (RR) and BSC management
                                 • Uses SCCP connectionless service
                          –    Direct Transfer Application Part (DTAP)
                                • Transfer of Call Control (CM) messages
                                • Transfer of Mobility Management (MM) messages
                                • Uses SCCP connection-oriented service




coMPAss Product Training 14-15 May, Singapore

Slide 69
   Basic format of SCCP message
                                                                        F     B
           F     CK            SIF              Label   SIO       LI    I FSN I     BSN F
                                                                        B     B


                                                                               Sub-service   Service Indicator
                                                                                  Field          0011
                           Message                 Originating   Destination
  SCCP User Data            type           SLS
                                                   Point Code    Point Code
           N x 8 bits          8 bits 4 bits        14 bits       14 bits
       Mandatory fixed part
       Mandatory variable part
       Optional part




coMPAss Product Training 14-15 May, Singapore

Slide 70
   SCCP Message Types
       Protocol
                                                 Message type                     Code
      0 class 3
         1 2
                 X     X           CR           Connection Request               0000 0001
                 X     X           CC           Connection Confirm               0000 0010
                 X     X           CREF         Connection Refused               0000 0011
                 X     X           RLSD         Released                         0000 0100
                 X     X           RLC          Release Complete                 0000 0101
                 X                 DT1          Data Form 1                      0000 0110
                       X           DT2          Data Form 2                      0000 0111
                       X           AK           Data Acknowledgement             0000 1000
      X     X                      UDT          Unitdata                         0000 1001
      X     X                      UDTS         Unitdata Service                 0000 1010
                       X           ED           Expedited Data                   0000 1011
                       X           EA           Expedited Data Acknowledgement   0000 1100
                       X           RSR          Reset Request                    0000 1101
                       X           RSC          Reset Confirm                    0000 1110
                 X     X           ERR          Protocol Data Unit Error         0000 1111
                 X     X           IT           Inactivity Test                  0001 0000




coMPAss Product Training 14-15 May, Singapore

Slide 71
SCCP Message Types, Class 0 and 2.

                       UDT (Unitdata) Class 0
                         – Used by a SCCP wanting to send data in a connectionless
                              mode.
           BTS


                       DT1 (Data Form 1) Class 2
                         – A Data Form 1 message is sent by either end of a signalling
                              connection to pass transparently SCCP user data between
                              two SCCP nodes.

                       Note: Only point to point signalling route is used in at the A-inter
                        phase, meaning that the MTP does not have to contain the functions
                        related to the signalling transfer point (STP) and multiple signalling-
                        route management.




coMPAss Product Training 14-15 May, Singapore

Slide 72
           A-Interface
           BSSAP
           BTS




coMPAss Product Training 14-15 May, Singapore

Slide 73
           Base Station Subsystem Application Part
           (BSSAP)


                       ETSI has specified an SS7 Base Station Subsystem Application
           BTS
                        Part (BSSAP) as the user of the SCCP/MTP transport service.
                          – SCCP subsystem number for BSSAP is FEh.




coMPAss Product Training 14-15 May, Singapore

Slide 74
   BSSAP messages Structure
                                                                SIO       F     B
           F      CK                        SIF                 83h LI    I FSN I           BSN F
                                                                          B     B
                                   OCTET

               Discriminator       1     1      Discriminator                       SCCP Header
               00000000                         00000001                           SSN FEh: BSSAP

                                        2    DLCI
                                                                     DLCI Data Link Connection Identifier

                                                                     Bit no.: 8 7 6 5 4 3 2 1
               Length              3     2
                                           Length                            C2 C1 0 0 0 S3 S2 S1
               Indicator 1                 Indicator 1
                                                                     C2 C1 identifies signalling-radio channel
               Layer 3                          Layer 3                 (00: SDCCH/FACCH, 01: SACCH)
               Messages            n     n      Um Interface         S3-S1 is the SAPI on the radio interface
               Octet                            Octet
                  BSSMA                             DTAP
                  P



coMPAss Product Training 14-15 May, Singapore

Slide 75
           A-Interface
           BSSMAP
           BTS




coMPAss Product Training 14-15 May, Singapore

Slide 76
   BSSMAP Format



                              Information Element Identifier       Disc. 0 = BSSMAP     OCTET 1
           BTS
                             Content of Information Elements
                                                                     Length indicator   OCTET 2


                            Fixed Length Info. Element Format     BSSMAP message type

                                                                   BSSMAP message       OCTET
                              Information Element Identifier
                                                                                        n
                             Length of Information Elements

                             Content of Information Elements



                           Variable Length Info. Element Format




coMPAss Product Training 14-15 May, Singapore

Slide 77
  BSSMAP Messages, part 1

   Code                Message type
   0000- - - -        Assignment messages: (Setup of traffic channels)
       0001           - Assignment request
       0010           - Assignment complete
       0011           - Assignment failure

   0010- - - -        Release messages:
       0000           - Clear command           (Release of traffic channels)
       0001           - Clear complete
       0010           - Clear request
       0011           - SAPI "n" clear command (Control of layer 2 links with SAPI not equal
       0100           - SAPI "n" clear complete to 0 on the radio interface)
       0101           - SAPI "n" reject




coMPAss Product Training 14-15 May, Singapore

Slide 78
   BSSMAP Messages, part 2
   Code                Message type
   0001- - - -         Handover messages:
       0000            - Handover request           (To BSC: Request for handover to that BSC)
       0001            - Handover required          (To MSC: Inter-BSC/MSC handover required)
       0010            - Handover request ack       (To MSC: Acknowledge of Handover request)
       0011            - Handover command           (To BSC: Contains the new radio channel/BTS
                                                    to which the MS should switch)
           0100        -   Handover complete        (To MSC: Commanded handover complete)
           0110        -   Handover failure         (To MSC: Commanded handover unsuccessful)
           0111        -   Handover performed       (To MSC: BSC has performed intern. handover)
           1000        -   Handover candidate       (To BSC: MSC requests list of MS that could
                           enquire                  be handed over to another cell)
           1001        -   Handover candidate       (To MSC: Answer to Handover candidate
                           response                 enquire)
           1010        -   Handover required reject (To BSC: Required handover unsuccessful)
           1011        -   Handover detect          (To MSC: Commanded handover successful)




coMPAss Product Training 14-15 May, Singapore

Slide 79
   BSSMAP Messages, part 3
   Code                Message type
  0011- - - -         General messages:
      0000            - Reset                          (Initialisation of BSS or MSC due to failure)
      0001            - Reset Acknowledge
      0010            - Overload                       (Processor or CCCH overload)
      0011            - Trace invocation               (Start production of trace record)
      0100            - Reset Circuit                  (Initialisation of single circuit due to failure)
      0101            - Reset Circuit
                        acknowledge

  0100- - - -         Terrestrial resource messages:
      0000            - Block                          (Management of circuits/time slots
      0001            - Blocking acknowledge           between MSC and BTS)
      0010            - Unblock
      0011            - Unblocking acknowledge




coMPAss Product Training 14-15 May, Singapore

Slide 80
   BSSMAP Messages, part 4
   Code                Message type
   0101- - - -         Radio resource messages:
   0000                - Resource request         (Available radio channels in the BSS cells)
        0001           - Resource indication
        0010           - Paging                   (Paging of MS)
        0011           - Cipher mode command      (Commands start of cyphering)
        0100           - Classmark update         (Change of MS power class)
        0101           - Cipher mode complete     (Ciphering is successfully initiated)
        0110           - Queuing indication       (Indicates delay in assignment of traffic
                                                  channel)
           0111        -   Complete layer 3       (Contains first message received from MS;
                           information            sets up SCCP-connection at A-interface)




coMPAss Product Training 14-15 May, Singapore

Slide 81
           A-Interface
           DTAP
           BTS




coMPAss Product Training 14-15 May, Singapore

Slide 82
           Direct Transfer Application sub-Part
           (DTAP)


                       The Direct Transfer Application sub-Part (DTAP) is
           BTS          used to transfer call control and mobility management
                        messages to and from the MS;
                          – The layer-3 information in these messages is not
                               interpreted by the BSS.




coMPAss Product Training 14-15 May, Singapore

Slide 83
   DTAP Format



                              Information Element Identifier       Disc. 1 = DTAP       OCTET 1
           BTS
                             Content of Information Elements
                                                                     Length indicator   OCTET 2


                            Fixed Length Info. Element Format     BSSMAP message type

                                                                   BSSMAP message       OCTET
                              Information Element Identifier
                                                                                        n
                             Length of Information Elements

                             Content of Information Elements



                           Variable Length Info. Element Format




coMPAss Product Training 14-15 May, Singapore

Slide 84
           DTAP messages and elements


                       Layer 3 of the DTAP messages has the same format as
           BTS          BSSMAP messages.

                       The DTAP messages and information elements are
                        identical to the the transparent MM and CM listed in the
                        A-bis section.




coMPAss Product Training 14-15 May, Singapore

Slide 85
                                                BSC                                                    MSC

                                                SCCP CR (BSSMAP Comp layer 3 info (CM Service Request [MM]))

                                                SCCP CC (BSSMAP Cipher mode command)

                                                SCCP DT1 (BSSMAP Cipher mode complete)

                                                SCCP DT1 (DTAP (Setup [CM]))

                                                SCCP DT1 (DTAP (Call Proceeding [CM]))
           BTS
                                                SCCP DT1 (BSSMAP Assignment request)



A-Interface signalling
                                                SCCP DT1 (BSSMAP Assignment complete)

                                                SCCP DT1 (DTAP (Alerting [CM]))

example                                         SCCP DT1 (DTAP (Connect [CM]))
                                                    .                                              .
                                                    .
                                                    .                   Active call                .
                                                                                                   .
                                                    .                                              .
                                                SCCP DT1 (DTAP (Disconnect [CM]))

                                                SCCP DT1 (DTAP (Release [CM]))

                                                SCCP DT1 (DTAP (Release Complete [CM]))

                                                SCCP DT1 (BSSMAP Clear command)

                                                SCCP DT1 (BSSMAP Clear complete)

                                                SCCP RLSD

                                                SCCP RLC



coMPAss Product Training 14-15 May, Singapore

Slide 86
                 Inter-MSC
           BTS   Signalling
                 MAP


coMPAss Product Training 14-15 May, Singapore

Slide 87
  The System.

  ISUP /              Public Switched                ISUP /
   TUP              Telephone Network                 TUP                                                             Um
                          (PSTN
                            )



    Authen.                                      Equip. Id
              MAP                                                                                       BTS
    Centre                                       Register
     AUC                                           EIR
                                                                          Base                                        Mobile Station (MS)
                                                                         Station                            Base
       MAP                                     MAP                      Subsystem                       Transceiver
                 Home                Visitor           MAP                                               Base
                Location            Location                              (BSS)                            Station
                                                                                                      Transceiver
                                                                                                       Base
                Register            Register                                                                BTS
                                                                                                        Station
                                                                                                   Transceiver
                                                                                     A-bis          Base
                  HLR                 VLR                                                         Base BTS
                                                                                                      Station
                                                                                                 Transceiver
 Mobile                                           Mobile                  Base
Switching                                        Switching                                      Base BTS
                                                                                                   Station
                                                                                               Transceiver
                                                                         Station
 Centre                                           Centre                                             BTS
                                                                                                 Station
                                                                                             Transceiver
                            MAP                                         Controller
  MSC                                              MSC        A-Inter                             BTS
                                                                                               Station
                           ISUP /                                         BSC
                                                                                                BTS
                            TUP



                                                                                                                2 Mbit/s PCM
                                                                                                                Air Interface




 coMPAss Product Training 14-15 May, Singapore

 Slide 88
   Protocol Architecture
                        MS                           BTS                                    BSC                                MSC

                        CM                    (CM)          (CM)                     (CM)        DTAP
                                                                                                                  CM
                                                                                                                                       I
                        MM                    (MM)          (MM)                     (MM)      (CM+MM)                 MM              S
                                                                                                                                   MAP
                                                                                                                                       U
  BTS                                         (RR)          (RR)                                                                       P
                                                                                                                   BSSMAP        TCAP
                        RR                                                          RR            BSSMAP

                                        RR'                                     BTSM              SCCP                  SCCP     SCCP
                                                              BTSM
                   Sig. layer 2         Sig. layer 2    Sig. layer 2           Sig. layer 2
                   (LAPDm)              (LAPDm)         (LAPD)                 (LAPD)
                                                                                                  MTP                   MTP          MTP
                   Layer 1 (air)        Layer 1 (air)   Sig. layer 1           Sig. layer 1


                              Um Interface                         Abis Interface                        A Interface                       Inter-MSC


                      DTAP - Direct Transfer Application Part                             SCCP - Signalling Connection Control Part
                      BSSMAP - BSS Management Application Part                            MAP - Mobile Application Part
                      CM - Call Management                                                TCAP - Transaction Capability Application Part
                      MM - Mobile Management                                              ISUP - ISDN User Part
                      RR - Radio Resource Management                                      MTP - Message Transfer Part
                      BTSM - BTS Management




coMPAss Product Training 14-15 May, Singapore

Slide 89
   Inter-MSC Signalling

                           The inter-MSC interfaces are:
                              –   The MSC-VLR interface.
           BTS
                              –   The MSC-HLR interface.
                              –   The HLR-VLR interface.
                              –   The MSC-MSC interface.
                              –   The MSC-EIR interface.
                              –   The VLR-VLR interface.
                              –   The MSC-ISDN/telephone network interface.




coMPAss Product Training 14-15 May, Singapore

Slide 90
   MAP

                           MAP = Mobile Application Part

           BTS
                           Users: MSC, HLR, VLR, EIR

                           Applications:
                              –   Location updating/roaming
                              –   Incoming call routing information (MSRN)
                              –   Subscriber service information
                              –   Non-call related supplementary services
                              –   Short message service delivery
                              –   MS equipment identity (IMEI)
                              –   Charging information



coMPAss Product Training 14-15 May, Singapore

Slide 91
   MAP Operations Part 1

                                     Value      Operation
                                      1          Update location area
                                      2          Update location
                                      3          Cancel location
           BTS                        4          Provide roaming number
                                      5          Detach IMSI
                                      6          Attach IMSI
                                      7          Insert subscriber data
                                      8          Delete subscriber data
                                      9          Send parameters
                                      10         Register SS
                                      11         Erase SS
                                      12         Activate SS
                                      13         Deactivate SS
                                      14         Interrogate SS
                                      15         Invoke SS
                                      16         Forward SS notification
                                      17         Register password
                                      18         Get password
                                      19         Process unstructured data



coMPAss Product Training 14-15 May, Singapore

Slide 92
   MAP Operations Part 2

                                     Value      Operation
                                      20         Send info for incoming call
                                      21         Send info for outgoing call
                                      22         Send routing information
           BTS                        23         Complete call
                                      24         Connect to following address
                                      25         Process call waiting
                                      26         Page
                                      27         Search for mobile subscriber
                                      28         Perform handover
                                      29         Send end signal
                                      30         Perform subsequent handover
                                      31         Allocate handover number
                                      32         Send handover report
                                      33         Process access signalling
                                      34         Forward access signalling
                                      35         Note internal handover
                                      36         Register charging information
                                      37         Reset
                                      38         Forward check SS indication



coMPAss Product Training 14-15 May, Singapore

Slide 93
   MAP Operations Part 3

                                     Value      Operation
                                      39         Authenticate
                                      40         Provide IMSI
                                      41         Forward new TMSI
           BTS                        42         Set ciphering mode
                                      43         Check IMEI
                                      45         Send routing info for SM
                                      46         Forward short message
                                      47         Set message-waiting data
                                      48         Note MS present
                                      49         Alert service centre
                                      50         Activate trace mode
                                      51         Deactivate trace mode
                                      52         Trace subscriber activity
                                      53         Process access request
                                      54         Begin subscriber activity




coMPAss Product Training 14-15 May, Singapore

Slide 94
                                                Visited side                               Home side
                                                BEGIN

                                                INVOKE            (Update Location)
           BTS
                                                CONTINUE

MAP - signalling                                INVOKE          (Insert Subscriber Data)

Location Updating                               CONTINUE

example                                         RETURN RESULT (Insert Subscriber Data)

                                                END


                                                RETURN RESULT       (Update Location)




coMPAss Product Training 14-15 May, Singapore

Slide 95
                 TRAU
             Transcoder
           BTS                                  Rate Adaptation Unit




coMPAss Product Training 14-15 May, Singapore

Slide 96
 TRAU

                          TRAU - Transcoder / Rate Adaptation Unit Functions:
                             – Conversion of speech from 64 kbit/s on PCM (A-law) to 13/6.5
              BTS
                                 kbit/s on the GSM radio interface
                             –   Intermediate rate adoption of data from V.110 frames to the
                                 special TRAU frames on the A-bis interface




coMPAss Product Training 14-15 May, Singapore

Slide 97
   Possible Locations of the TRAU.
                                                T
                                                R
                                     BTS        A             BSC                      MSC
                                                U



                                                                        T
                                                                        R
                                     BTS                      BSC       A              MSC
                                                                        U



                                                                              T
                                                                              R
                                     BTS                      BSC             A        MSC
                                                                              U



                          Um                         A-bis                    A-Interface


                                                    13Kbit/s speech channel


coMPAss Product Training 14-15 May, Singapore

Slide 98
   GSM Speech Encoding

                      Bandwidth: 13 kbit/s
                      Encoding algorithm: Regular Pulse Excitation with Long Term
                       Prediction (RPE LTP):
              BTS       –    Speech is sampled 8000 times per second
                        –    Each sample is converted into a 13 bit digital value
                        –    Every 20 ms a 260 bit segment is generated (13 kbit/s)
                        –    The segment is divided by importance into 182 class 1 bits and 78 class
                             2 bits
                        –    For protection, the 182 class 1 bits are mapped into 378 bits
                        –    The resulting 456 bits (378 + 78) are divided into 8x57 bits
                        –    The data are transmitted in 4 consecutive TDMA blocks
                      Resulting overall delay is 57.5 msec.



coMPAss Product Training 14-15 May, Singapore

Slide 99
 Control of TRAU


                           TRAU is controlled by BTS

              BTS
                           In-band signalling used, if TRAU not at BTS

                           Control functions:
                              –   Shift between speech and data
                              –   Shift between full rate and half rate channels
                              –   Timing of speech frames (BSS - MS)
                              –   Comfort noise (Discontinuous Transmission)




coMPAss Product Training 14-15 May, Singapore

Slide 100
                           GSM
            BTS            Signalling
                           procedures


coMPAss Product Training 14-15 May, Singapore

Slide 101
   Special signalling procedures for GSM

                            Call Management
                               – Ordinary Call Control (as usual)
                            Mobility Management
            BTS                – Location Updating (Roaming)
                               – Authentication
                            Radio Resource Management
                               –    Paging
                               –    Network Access
                               –    Encryption
                               –    Radio Signal Control
                               –    Radio Signal Measurements
                               –    Handover




coMPAss Product Training 14-15 May, Singapore

Slide 102
    Location Updating (Roaming)                                                        VLR

   An MM procedure                                                                    MSC

   Reasons for roaming:                                                           Area 1
      – MS has detected that it has entered
            into a new location area (by listening
            to Broadcast system info)
   Types of roaming:
      – Inside same VLR area
              • The HLR does not need to know
                                                           BTS                   BTS


      –     Another VLR area                                           SONOFON

                                                                       M    N




             • In this case the HLR is
                informed
                                                                                       VLR

                                                                                   MSC
                                                     BTS         BTS
                                                                                  Area
                                                                                  2


coMPAss Product Training 14-15 May, Singapore

Slide 103
Handovers.
                                                         A RR procedure
                                                         The Handover process is the
                                                          situation where a Mobile Station
                                                          changes from being served by one
                                                          Antenna to another
                                                         Handovers take place during a call
                                                         Handover are done automatically
            BTS                                 BTS
                                                         Crossing the boundary of two
                                                          adjacent cells is the typical example
                                                          of a Handover




coMPAss Product Training 14-15 May, Singapore

Slide 104
      Handovers.
   Major types of handovers
      – Intra BSC                                                              MSC - A         Inter MSC
      – Inter BSC
      – Inter MSC                                                                                          MSC - B

   Purpose of handover                                   Inter BSC

      – Poor quality connection
                •
              Avoid loosing contact
              to the mobile station
      –   Fault in the MS or BTS/BSC                                    BSC              BSC
                                                    Intra BSC
      –   Network management                                                                               BSC
                                                                                               SONOFON

                                                                                               M    N




                                                        BTS

                                                                                         BTS                         SONOFON

                                                                                                                     M    N




                                                              SONOFON

                                                              M    N




                                                                         BTS
                                                                                                            BTS




    coMPAss Product Training 14-15 May, Singapore

    Slide 105
 Call Setup


                         A CM procedure
                         Distinguish two types
            BTS             – Mobile Terminating Call
                                   •
                                 i.e. a call from the fixed network to a Mobile
                                 Station
                            – Mobile Originating Call
                               • i.e. a call from a Mobile Station to the fixed
                                 network




coMPAss Product Training 14-15 May, Singapore

Slide 106
 Mobile Terminating Call


                        Problems and answers
                           – Where in the world is the Mobile Station
            BTS
                                  •
                                  Look it up in the HLR
                                  •
                                  (The HLR may have to ask the VLR)
                           –   How to Make the Mobile Station Aware that a call is waiting
                                • Page it in the cell where it is located
                           –   What does the MS do when being paged ?
                                • Asks for a Radio channel
                                • Tells the system that it is ready

                        Now the usual setup flow follows



coMPAss Product Training 14-15 May, Singapore

Slide 107
  Incoming Call
MS                BTS                BSC           MSC            VLR             HLR          GMSC               ISDN
                                                                                                    IAM (MSISDN, service)
                                                                                   Send Routing Info (MSISDN)
                                                                    Provide Roaming Number (IMSI)
                                                                    Roaming Number (MSRN)
                                                                                  Routing Info (MSRN)
                                                    IAM (MSRN, service)
                                                    Send Info Incoming Call (MSRN, service)
                                                    Page (IMSI, TMSI, LAI)
                      Paging Request (TMSI) [RR]
                                   Channel Request [RR]
                                   Immediate Assign [RR]
                     Paging Response (TMSI) [RR]
                                                   Page Result
                      SETUP (service) [CM]          Complete Call (service)
                  Call Confirm [CM]
            Assign Command [RR] Assign Req [RR]
                   Assign Complete [RR]
                    Alerting [CM]                     ACM
                    Connect [CM]
                                                     ANM
                  Connect Ack [CM]
                                                    Complete Call Result
                                                                                               Um/A-bis/A signalling
                                                                                               MAP signalling
                                                                                               ISUP/TUP signalling


coMPAss Product Training 14-15 May, Singapore

Slide 108
 Mobile Originating Call


                     Problems and Answers
                        – How the mobile gets in contact with the network
            BTS
                               •
                               Switch the MS on
                               •
                               Request a channel
                               •
                               Tell the network what kind of service is wanted
                        –   How does the network respond
                             • Verifies the Mobile identity (authentication)
                             • Assigns a traffic channel

                     And then everything proceed as usual




coMPAss Product Training 14-15 May, Singapore

Slide 109
 Outgoing Call from MS
MS                       BTS                    BSC                    MSC                 VLR                       ISDN
      Channel Request/Required [RR]
               Immediate Assign
               [RR]
            CM Service Req (IMSI, transact) [MM]                        Process Access Request
     CM copy [MM]
                                                                        Authenticate (RAND)
                Authentication Request (RAND) [MM]
                   Authentication Response (SRES) [MM]                  Authentication Response (SRES)
                                                                        Set ciphering mode (key)
                                                                        Access Request
                 Ciphering Command (key)
            Ciphering Mode Mode Complete [RR]                           Ack
                 [RR]
                     SETUP (service, called number) [CM]
                       Call Proceeding                                   Send info
                                                                         Complete for o/g (service, called number)
                       [CM]
                    Assign Command                    Assign Request     call
                    [RR] Complete
                    Assign                            [RR]
                    [RR]                                                     IAM
                                                                             ACM
                               Alerting
                               Connect [CM]
                               [CM]                                          ANM
                             Connect Ack
                             [CM]


                                                                                                   Um/A-bis/A signalling
                                                                                                   MAP signalling
                                                                                                   ISUP/TUP signalling


coMPAss Product Training 14-15 May, Singapore

Slide 110

				
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