Presentation                 by         G. Govindarajan      Dy. General Manager (Rtd)Mahanagar Telephone Nigam Limited (M...
GSM Spectrum  Cell Principles   SectorisationFrequency Planning                     GGRajan
RADIO SPECTRUM                 GGRajan
GSM Frequency Spectrum1] GSM 9001] GSM 900UplinkUplink     : 890 MHz to 915 MHz           : 890 MHz to 915 MHz            ...
GSM Frequency Spectrum                      GSM Spectrum [900 MHz]                                                        ...
GSM Frequency Spectrum                            B                            T                            S890 MHz      ...
Cell PrinciplesCELL : a Base Station(Transmitter) having numberof RF channels. Usually aHexagonal shape.                  ...
Cell Principles                      COVERAGE AREA                    Each Cell covers a                    limited number...
Cell PrinciplesCELL RADIUS : Radial distance of a Cell                    Approximately : 25 KMs ( Start up )             ...
Cell Principles                              Frequency Reuse         GSM has 124 frequencies for use in network         Al...
Cell SectorisationOmni Antenna     3 Sectored Cell Site       6 Sectored Cell Site                   F2                   ...
Cell Sectorisation3 Sectored Cell Site                       GGRajan
Frequency Planning                  4 / 12 LayoutA1 B1 C1 D1 A2 B2 C2 D2 A3 B3 C3 D31 2 3 4 5 6 7 8 9 10 11 1213 14 15 16 ...
Frequency PlanningA1 B1 C1       A2   B2     C2        A3    B3 C31  2  3        4    5      6         7     8  910   11  ...
Frequency PlanningTypical Cellular Radio Plan                              GGRajan
GSM Architecture  SIM AnatomyBSS ArchitectureNSS Architecture                   GGRajan
GSM Architecture                   GSM SYSTEM Base Station       Switching          OMC /NMC Subsystem          Subsystem ...
GSM Architecture                        NSS                      MSC/VLR                  BSS Architecture           BSC  ...
GSM Architecture                                           BTS: Base Transceiver Station                 NSS Architecture ...
GSM Architecture                            BTS Functions◄Encodes, Encrypts, Multiplexes, Modulates andfeeds RF to Antenna...
GSM Architecture      BSC Functions    Allocation of radio channels    Receives MS measurements    Inter-cell handovers fr...
GSM Architecture                        MSC FunctionsPaging, specifically call handlingDynamic allocation of resources in ...
GSM Architecture               Visitor Location Register                IMSI & TMSI                 IMSI & TMSI           ...
GSM Architecture       Home Location Register►Stores►Stores      MS             MS     Parameters,                    Para...
GSM Architecture              Equipment Identity RegisterStores IMEI for all registered MS and is unique to every MS.Only ...
SIM Anatomy                        SIM         (Subscriber Identification Module)A removable card.Contains an IC chip with...
SIM Anatomy                          Programs in SIM  1 . IMSI (International Mobile Station Identity)  2 . Ki (Individual...
SIM AnatomySIM Authentication Process                                        VLR              IMSI    RAND                ...
SIM Anatomy                     MSISDN        Numbering for Cellular Mobile Network ACCESS               MSC CODE         ...
GSM Architecture - Review                                 NMC                                 NMC                   VLR   ...
Physical & Logical ChannelsTraffic & Control Channels      TDMA Frames  Super & Hyper Frames                              ...
GSM Channels              Physical ChannelsGSM RF carrier can support up to 8 MS simultaneouslyEach MS occupy 1 Time SlotI...
GSM Channels                       Logical ChannelsOne or more logical channels are transmitted on a Physical channel.Dete...
GSM Channels         Traffic Channels on Air Interface                      TCH (Traffic Channel)                      TCH...
GSM Channels                 Traffic channel TypesTraffic channels are used to send Speech or Data services.May also be us...
GSM Channels                    Control Channels                CCH (Control Channel)                CCH (Control Channel)...
GSM Channels                            BCCH                 Broadcast Control ChannelParameters, LAI, CI, Neighbor Cells,...
GSM Channels                       CCCH Types            RACHUsed in uplink by MSs for requestinga channel for a connectio...
GSM Channels                                                        DCCH                                                  ...
GSM Channels                          ACCH                        ACCH                                                    ...
GSM Frames                      TDMA Frame        TDMA FRAME - 1                     TDMA FRAME - 20   1   2     3   4    ...
GSM Frames                     TDMA Multi Frame                     26-TDMA multi-frameSuccession of 26 TDMA frames, and c...
GSM Frames            Low Capacity Cell            Combined        BCCH / CCCH / DCCH0   1      2     3     4        5   6...
GSM Frames        Higher Capacity Cell          Combined        BCCH / CCCH0   1     2    3      4   5      6   7         ...
GSM Frames                         26 Frame Traffic Channel Multiframe                                     0 . 577 ms     ...
GSM Frames                       51 Frame Control Channel Multiframe                                             TS-4     ...
GSM Frames                              Superframe & Hyperframe                              0         1        2      3  ...
Mobile Originated CallMobile Terminated Call GSM Call Handover                         GGRajan
Mobile Call PhasesPhases of Mobile Originated Call  / Setup phase.  / Ringing phase.  / Conversation phase.  / Release pha...
GSM Call flow            Base Station Subsystem            BSC-1        Voice Call                                        ...
GSM Call flow     Circuit-Switched Data Call                                            Public                            ...
Handover Management                         Mobile Hand-offSignal Strength                           Handoff Zone         ...
Handover Management             Four types of handovers in GSM..Channels (TS) in the same Cell  Channels (TS) in the same ...
Handover Management         MSC              MSC         BSC           BSC      BSC LAI-B                          LAI-AIn...
Handover Management                                BSC           MSCVLR               BTS-A                               ...
General Packet Radio Service (GPRS)Enhanced Data rate for GSM Evolution (EDGE)                                            ...
What is GPRS ? / GPRS is a new bearer service for GSM / Packet Data Network (PDN) to the Internet.GPRS benefit from shorte...
GSM vs GPRS                         GPRS Architecture                                  GSM Core                  BSC      ...
GPRS System Architecture                        GPRS in GSM Networks     Packets                                Same Radio...
EDGE Features  EDGE acts as a bolt-on enhancement to 2G and 2.5G, ie GPRS  EDGE is also known as Enhanced GPRS, a superset...
GPRS - EDGE compared         Technical Differences - GPRS and EDGETechnology     Data Rates       Spectrum         Service...
GGRajan
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Gsm technology

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Understanding of GSM Technology for Engineering Students

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  1. 1. Presentation by G. Govindarajan Dy. General Manager (Rtd)Mahanagar Telephone Nigam Limited (MTNL) Mumbai GGRajan
  2. 2. GSM Spectrum Cell Principles SectorisationFrequency Planning GGRajan
  3. 3. RADIO SPECTRUM GGRajan
  4. 4. GSM Frequency Spectrum1] GSM 9001] GSM 900UplinkUplink : 890 MHz to 915 MHz : 890 MHz to 915 MHz GSM SpectrumDownlink : 935 MHz to 960 MHzDownlink : 935 MHz to 960 MHzARFCNARFCN : 124 : 1242] EGSM 9002] EGSM 900UplinkUplink : 880 MHz to 915 MHz : 880 MHz to 915 MHz 3] GSM 1800 (DCS 1800) 3] GSM 1800 (DCS 1800)Downlink : 925 MHz to 960 MHzDownlink : 925 MHz to 960 MHz Uplink Uplink : 1710 MHz to 1795 MHz : 1710 MHz to 1795 MHzARFCNs : 174ARFCNs : 174 Downlink : 1805 MHz to 1880 MHz Downlink : 1805 MHz to 1880 MHz ARFCNs : 374 ARFCNs : 374 Absolute Radio Frequency Channels : 4] PCS 1900 4] PCS 1900 BW - 200 KHz, TDMA Slots - 8 Uplink Uplink : 1850 MHz to 1910 MHz : 1850 MHz to 1910 MHz Downlink : 1930 MHz to 1990 MHz Downlink : 1930 MHz to 1990 MHz ARFCNs : 299 ARFCNs : 299 GGRajan
  5. 5. GSM Frequency Spectrum GSM Spectrum [900 MHz] Time Code• UL band : 890 - 915 MHz• DL band : 935 - 960 MHz TS-8• Duplex spacing: 45 MHz A FDMA structure: 124 RFs (ARFCN) TS-2 M• TD TS-1• RF Band width: 200 KHz Freq• TDMA structure: 8 Timeslots/ RF RF-1 RF-2 RF-3 FDMA 960 Mhz 124 • • RF • 1 2 3 4 5 6 7 8 • 2 TDMA structure of each ARFCN 1 935 Mhz GGRajan
  6. 6. GSM Frequency Spectrum B T S890 MHz 915 MHz 935 MHz 960 MHz 1 2 3 124 1 2 3 124 UPLINK FREQUENCY DOWNLINK FREQUENCY GGRajan
  7. 7. Cell PrinciplesCELL : a Base Station(Transmitter) having numberof RF channels. Usually aHexagonal shape. 2 7 3CLUSTER: Group of cells. 1Size > 3, 4, 7, 9 or 12 6 4 5 GGRajan
  8. 8. Cell Principles COVERAGE AREA Each Cell covers a limited number of - 70 dBm Mobile Subs within the Cell boundaries. - 80 dBm - 90 dBm - 100 dBm GGRajan
  9. 9. Cell PrinciplesCELL RADIUS : Radial distance of a Cell Approximately : 25 KMs ( Start up ) 1 KM ( Mature )CELL SIZE : Large Cells are employed in: Remote areas Coastal regions Areas with few subscribers Small cells are used in: Urban areas Areas with high subscriber density GGRajan
  10. 10. Cell Principles Frequency Reuse GSM has 124 frequencies for use in network Allocated to more than one network operator If 4 operators, then each will get only 31 frequencies Maximum cell radius is approximately 35 KMs Network provider must re-use the same frequencies 2 7 3 Q = D/R = 3N (if all cells 1 with same Radius) R 6 4 N - Cluster size, R - Cell Radius D - Distance between two co-channels 5 DHigh Q > Less interference – Less Traffic capacity 1Low Q > Higher interference – Higher capacity GGRajan
  11. 11. Cell SectorisationOmni Antenna 3 Sectored Cell Site 6 Sectored Cell Site F2 1 1 6 2 3 F1 5 3 2 4 F3 Sectorisation splits a single site into a number of cells Each sector cell has TX and RX antennas Each sector behaves as an independent cell GSM = 4/12 : 4 Cell Sites, each with 3 Sectors DAMPS = 7/21 : 7 Cell Sites, each with 3 Sectors CDMA = 1/3 : 1 Cell Site, each with 3 Sectors GGRajan
  12. 12. Cell Sectorisation3 Sectored Cell Site GGRajan
  13. 13. Frequency Planning 4 / 12 LayoutA1 B1 C1 D1 A2 B2 C2 D2 A3 B3 C3 D31 2 3 4 5 6 7 8 9 10 11 1213 14 15 16 17 18 19 20 21 22 23 2425 26 27 28 29 30 31 32 33 34 35 36 A1 A2 D1 A3 B1 D2 B2 A1 C1 D3 B3 A2 C2 D1 A3 B1 C3 D2 B2 D3 C1 B3 C2 C3 GGRajan
  14. 14. Frequency PlanningA1 B1 C1 A2 B2 C2 A3 B3 C31 2 3 4 5 6 7 8 910 11 12 13 14 15 16 17 18 3 / 9 Layout19 20 21 22 23 24 25 26 2728 29 30 31 32 33 34 35 36 A1 A1 A2 A2 A3 B1 A3 B1 B2 B2 C1 B3 C1 B3 C2 C2 C3 A1 C3 A2 A3 B1 B2 C1 B3 C2 C3 GGRajan
  15. 15. Frequency PlanningTypical Cellular Radio Plan GGRajan
  16. 16. GSM Architecture SIM AnatomyBSS ArchitectureNSS Architecture GGRajan
  17. 17. GSM Architecture GSM SYSTEM Base Station Switching OMC /NMC Subsystem Subsystem Subsystem Base Station Mobile SwitchingController (BSC) Centre (MSC)Base Transceiver Registers AUC Station (BTS) HLR VLR EIR GGRajan
  18. 18. GSM Architecture NSS MSC/VLR BSS Architecture BSC BSC Abis BTS BTS BTS BTS MSMS MS MS GGRajan
  19. 19. GSM Architecture BTS: Base Transceiver Station NSS Architecture BSC: Base Station Controller MSC: Mobile Switching CenterPSTNPSTN VLR: Visiting Location Register HLR: Home Location Register GMSC NSS IWF: InterWorking Function HLR / AuC SS7 SS7 VLR STP MSC EIR CSE IWF SM-SC MSC / VLR VMS Internet Internet BSS BSC BTS BTS MS GGRajan
  20. 20. GSM Architecture BTS Functions◄Encodes, Encrypts, Multiplexes, Modulates andfeeds RF to Antenna◄Received signals is Decoded, Decrypted andDemodulate◄Trans-coding and Rate Adoption Functionality◄11 power classes from .01 watts (Micro cell) to 320watts◄Frequency hopping NOKIA BTS◄Up-link radio channel measurements◄Multiple Antennas for Diversity LUCENT BTS GGRajan
  21. 21. GSM Architecture BSC Functions Allocation of radio channels Receives MS measurements Inter-cell handovers from BTS to BTS Concentrator for low capacity BTSs Reduce the number of connections to MSC Data stored in BSC►Carrier frequencies►Frequency hopping lists►Power reduction levels►Levels for cell border calculation GGRajan
  22. 22. GSM Architecture MSC FunctionsPaging, specifically call handlingDynamic allocation of resources in coordination with BSSLocation registrationHandover managementBilling for all subscribers based in its areaReallocation of frequencies to BTSs to meet heavy demandsSignaling interface to databases like HLR, VLR.Gateway to SMS between SMS centers and subscribersHandle inter working function while working as GMSC GGRajan
  23. 23. GSM Architecture Visitor Location Register IMSI & TMSI IMSI & TMSI MSISDN MSISDNVLR Data MSRN MSRN Location Area Location Area MS category MS category Authentication Key Authentication KeyMain task of VLR is to reduce the number of queries to HLRControls those mobiles Roaming in its area.One VLR may be in-charge of one or more LA.VLR gets updated from HLR, whenever a new MS enters its area.Authentication along with HLR and AUC.Relays ciphering key from HLR to BSS.Assign TMSI and periodically changes to secure MS’s identity.IMSI detach and attach operation GGRajan
  24. 24. GSM Architecture Home Location Register►Stores►Stores MS MS Parameters, Parameters, Numbers, Numbers,Authentication & Encryption values.Authentication & Encryption values.►Current MS status and associated VLR.►Current MS status and associated VLR.►One PLMN may contain one or several HLR.►One PLMN may contain one or several HLR. Authentication Centre ►Protect against intruders in air interface ►Protect against intruders in air interface ►Authentication (Ki) and Ciphering (Kc) keys stored ►Authentication (Ki) and Ciphering (Kc) keys stored securely securely ►Cipher key changes randomly with each phone call ►Cipher key changes randomly with each phone call ►A separate entity and physically included in HLR ►A separate entity and physically included in HLR GGRajan
  25. 25. GSM Architecture Equipment Identity RegisterStores IMEI for all registered MS and is unique to every MS.Only one EIR per PLMN.White list : IMEI, assigned to valid MS.Black list : IMEI reported stolenGray list : IMEI having problems like faulty software, wrong make of equipment etc. GGRajan
  26. 26. SIM Anatomy SIM (Subscriber Identification Module)A removable card.Contains an IC chip with a microprocessor.Contains RAM and ROM.It is inserted in ME at the time of making or receiving a call. GGRajan
  27. 27. SIM Anatomy Programs in SIM 1 . IMSI (International Mobile Station Identity) 2 . Ki (Individual Subscriber authentication Key) 3 . A3 (Authentication Algorithm ) 4 . A8 [ Cipher Key (Kc) Algorithm ] IMSI Ki 5 . A5 (Encryption Algorithm ) A3 A8• IMSI & Ki are specific to each MS A5• A3 & A8 can be different for different operators• A5 - Unique, used across GSM operators GGRajan
  28. 28. SIM AnatomySIM Authentication Process VLR IMSI RAND RAND Ki Ki Ki Ki A3 A8 A3 A8 Kc Kc SRES SRES SIM in MS NET WORK GGRajan
  29. 29. SIM Anatomy MSISDN Numbering for Cellular Mobile Network ACCESS MSC CODE MOBILE CODE NUMBER 2-digit 3-digit 5-digit98/94 etc. ABC XXXXX GGRajan
  30. 30. GSM Architecture - Review NMC NMC VLR VLR HLR AUC OMC OMC EIR MSC MSC Terrestrial Interfaces MSC MSC XC IWF EC EC IWF XC BTS BTS BSC BSC BTS BTS BSC BSC BTS BTS PSTN PSTNBTS BTS BTS BTS BTS BTS BTS BTS BTSBTS BTS BTS BTS BTS GGRajan
  31. 31. Physical & Logical ChannelsTraffic & Control Channels TDMA Frames Super & Hyper Frames GGRajan
  32. 32. GSM Channels Physical ChannelsGSM RF carrier can support up to 8 MS simultaneouslyEach MS occupy 1 Time SlotInformation carried in TS is “BURST”Each TS carrying Burst is a “Physical Channel”8 Time Slots forms 1 TDMA Frame GGRajan
  33. 33. GSM Channels Logical ChannelsOne or more logical channels are transmitted on a Physical channel.Determined by the information transmitted over it. Types of Logical Channels Logical Channels Logical Channels Traffic Channels Control Channels Broadcast Common Control Dedicated Control GGRajan
  34. 34. GSM Channels Traffic Channels on Air Interface TCH (Traffic Channel) TCH (Traffic Channel) NB NB SPEECH SPEECH DATA DATA TCH/FS TCH/FS TCH/HS TCH/HS TCH/9.6 TCH/9.6 TCH/2.4 TCH/2.4 TCH/EFR TCH/EFR TCH/4.8 TCH/4.8 SACCH SACCH NB: NB: Normal Burst Normal BurstTCHTCH SACCH: Slow Associated Control Chl. SACCH: Slow Associated Control Chl. FACCH: Fast Associated Control Chl. FACCH: Fast Associated Control Chl. FACCH FACCH GGRajan
  35. 35. GSM Channels Traffic channel TypesTraffic channels are used to send Speech or Data services.May also be used for sending information. Example: call forwarding and short messages Traffic channel Types based on transmission rates TCH/FS (Full rate Speech) - gross bit rate of 22.8 kbps TCH/HS (Half rate Speech) - gross bit rate of 11.4 kbps GGRajan
  36. 36. GSM Channels Control Channels CCH (Control Channel) CCH (Control Channel) NB NB/AB BCCH- BCCH- DCCH DCCH Downlink Only Downlink Only NB/DBSDCCHSDCCH ACCH ACCH BCCH BCCH SYNC. CHLS. SYNC. CHLS. SB FB CCCH CCCHFACCHFACCH SACCH SACCH SCH SCH FCCH FCCH AB NB RACH RACH NB CBCH CBCH FB: Freq. Burst FB: Freq. Burst Uplink Uplink Downlink Downlink SB: Sync. Burst SB: Sync. Burst AB: Access Burst AB: Access Burst PCH/AGCH PCH/AGCH DB: Dummy Burst DB: Dummy Burst Downlink Downlink GGRajan
  37. 37. GSM Channels BCCH Broadcast Control ChannelParameters, LAI, CI, Neighbor Cells, Frequencies used in cell etcare transmitted to MS. FCCH (Frequency Correction Channel) BCCH- BCCH-FCCH transmits a constant frequency Downlink Only Downlink Onlyshift of the RF carrier that can be used NB/DBby the MS for frequency correction. BCCH SYNC. CHLS. BCCH SYNC. CHLS. SB FB SCH SCH SCH FCCH FCCH Synchronization ChannelSCH is used to time synchronize the MSs,carries TDMA frame number and BSIC(Base Station Identity Code). GGRajan
  38. 38. GSM Channels CCCH Types RACHUsed in uplink by MSs for requestinga channel for a connection. CCCH CCCH CBCH AB NBUsed for the transmission of Short RACH RACH CBCH CBCHMessages as broadcast messages to Uplink Uplink Downlink Downlinkall MSs. PCH PCH/AGCH PCH/AGCH Downlink DownlinkUsed in Down link by BTS to page IMSI, TMSI or IMEI to the MS. AGCHUsed in downlink to allot DCCH, if MSrequested via RACH. GGRajan
  39. 39. GSM Channels DCCH DCCH DCCH Dedicated Control CHannel SDCCH ACCH SDCCH ACCH Fully duplex, Point to Point channels. FACCH SACCH FACCH SACCH Used for signaling between BTS and a certain MS. Assigned to a single MS for call setup & subs. validation. DCCH, a single TS on an RF carrier used to convey 8 SDCCHs. SDCCH Stand-alone Dedicated Control ChannelA duplex channel which is always allocated to a TCH or SDCCH.Used for transmission of signaling data, radio link supervisionmeasurements, TX power control and timing advance data. GGRajan
  40. 40. GSM Channels ACCH ACCH ACCH Associated Control Channel Can be associated with either SDCCH or TCH. FACCH SACCH FACCH SACCH Used for carrying information associated with the process being carried out on either SDCCH or the TCH. SACCH Slow Associated Control CHannel Conveys power control & timing information in downlink. SACCH is used for non urgent procedures. FACCH Fast Associated Control ChannelUsed for handovers, assignments, for call set-up and release. GGRajan
  41. 41. GSM Frames TDMA Frame TDMA FRAME - 1 TDMA FRAME - 20 1 2 3 4 5 6 7 0 1 2 3 4 5 6 7 Time Slot BURST TIME SLOT – 0.577 ms GGRajan
  42. 42. GSM Frames TDMA Multi Frame 26-TDMA multi-frameSuccession of 26 TDMA frames, and corresponds to the 26 x 8 BPor 120 ms. 51-TDMA multi-frameSuccession of 51 TDMA frames, and corresponds to the 51 x 8 BPcycle. SuperframeSccession of 51 x 26 TDMA frames (6.12 sec). HyperframeNumbering period, 2048 x 51 x 26 x 8 Broadcast Period long, or 3hours, 28 minutes, 53 seconds and 760 milliseconds. GGRajan
  43. 43. GSM Frames Low Capacity Cell Combined BCCH / CCCH / DCCH0 1 2 3 4 5 6 7 1 to 7 TRAFFIC GGRajan
  44. 44. GSM Frames Higher Capacity Cell Combined BCCH / CCCH0 1 2 3 4 5 6 7 1 to 7 TRAFFIC DCCH0 1 2 3 4 5 6 7 1 to 7 TRAFFIC GGRajan
  45. 45. GSM Frames 26 Frame Traffic Channel Multiframe 0 . 577 ms TIMESLOT TS-4 TDMA FRAME 0 1 2 3 4 5 6 7 0 1 2 3 4 5 6 7 4 . 615 ms MF0 ~ MF11 & MF13 ~ MF24 : Traffic : MF12 : SACCH : MF25 : Idle Idle 0 1 2 3 --- 12 -- 25 120 ms SACCH MULTIFRAMEMS needs to send information about signal strength from surrounding cells to thenetwork, Capacity required to send measurement info is 1/24 the capacity requiredto send voice. GGRajan
  46. 46. GSM Frames 51 Frame Control Channel Multiframe TS-4 0 . 577 ms TIMESLOT TDMA FRAME 0 1 2 3 4 5 6 7 0 1 2 3 4 5 6 7 4 . 615 ms IDLE 0 1 2 3 -- -- -- 12 --- -- 25 -- -- 49 50 MULTIFRAME 235.365 ms51 Frame structure occurs in several forms, depending on thetype of control channel and the network provider’s requirements GGRajan
  47. 47. GSM Frames Superframe & Hyperframe 0 1 2 3 4 5 6 7 4 . 615 ms TDMA Frame26 Frames Multiframe 51 Frames Multiframe 0 1 2 -- --- -- -- 49 500 1 2 3 --- 12 -- 25 120 ms 235.65 ms Traffic Channel Control Channel Repeat 51 times Repeat 26 times 0 1 2 3 --- 12 -- 25 Superframe - 6 . 12 Sec - 1326 TDMA frames0 25 50 2048 Superframes = 2715648 TDMA Frames0 1 2 ---- Hyperframe ---- ----- 2046 2047 3 H 28 M 53 S 760 ms GGRajan
  48. 48. Mobile Originated CallMobile Terminated Call GSM Call Handover GGRajan
  49. 49. Mobile Call PhasesPhases of Mobile Originated Call / Setup phase. / Ringing phase. / Conversation phase. / Release phase. Phases of Mobile Terminated Call Routing analysis Paging. Call setup. Call release. GGRajan
  50. 50. GSM Call flow Base Station Subsystem BSC-1 Voice Call Switching Centre HLR VLR VLR MSC AUC AUC EIR EIR FIBER LINK BTS-1 NK LI W M BTS-2 BTS-1 BSC-2 PSTNBTS contains TX and RX BSC Manages Radio resources, Radio channels and Local connection management GGRajan
  51. 51. GSM Call flow Circuit-Switched Data Call Public Switched Telephone Network HLRMS MSC / BSC VLR BTS Wireless Network Internet IWF MS GGRajan
  52. 52. Handover Management Mobile Hand-offSignal Strength Handoff Zone B B T T S S Distance GGRajan
  53. 53. Handover Management Four types of handovers in GSM..Channels (TS) in the same Cell Channels (TS) in the same Cell (Intra-BTS) (Intra-BTS)..Cells under the control of same BSC Cells under the control of same BSC (Inter-BTS) (Inter-BTS)..Cells under the control of different BSCs Cells under the control of different BSCs (Intra-MSC) (Intra-MSC)..Cells under the control of different MSCs Cells under the control of different MSCs (Inter-MSC) (Inter-MSC) GGRajan
  54. 54. Handover Management MSC MSC BSC BSC BSC LAI-B LAI-AInter MSC hand Off Intra BSC handoff Inter BSC hand Off GGRajan
  55. 55. Handover Management BSC MSCVLR BTS-A HLR BTS-B BSC MSC VLR•BSC-A informs MSC-A that MS needs handover from BTS-A to BTS-B•MSC-A informs MSC-B that a handover from BTS-A to BTS-B is underway•MSC-A commands BSC/BTS-A to proceed with handover to BTS-B. Hanoverfrom BTS-A to BTS-B is underway•BTS-A commands MS to change to a specified channel on BTS-B•BTS-B informs BSC/MSC that hand over is complete• MSC-B informs the old MSC-A that hand over to BTS-B is complete GGRajan
  56. 56. General Packet Radio Service (GPRS)Enhanced Data rate for GSM Evolution (EDGE) GGRajan
  57. 57. What is GPRS ? / GPRS is a new bearer service for GSM / Packet Data Network (PDN) to the Internet.GPRS benefit from shorter access times and higher data rates.“online” over a long period of time, but billed for data volume. GPRS improves the utilization of the radio resources, Offers volume-based billing, Higher data transfer rates, Shorter access times, Simplifies the access to packet data networks. GPRS includes GSNs SGSN : Serving GPRS Support Node GGSN : Gateway GPRS Support Node GPRS Register GGRajan
  58. 58. GSM vs GPRS GPRS Architecture GSM Core BSC Network PSTN/ISPAir Interface Solution GPRS Core Network IP SGSN IP GGSN PDN Network Solution GGRajan
  59. 59. GPRS System Architecture GPRS in GSM Networks Packets Same Radio BSS for Packet and Circuit Traffic Circuit BSC IP GPRS GGSN PLMN SGSN MSC/VLR Intra PLMN IP HLR SS7 Backbone SGSN GGSNGSM PLMN X.25 MSC GGRajan
  60. 60. EDGE Features EDGE acts as a bolt-on enhancement to 2G and 2.5G, ie GPRS EDGE is also known as Enhanced GPRS, a superset to GPRS Can carry data speeds up to 384 Kbps in packet mode Meet the ITUs requirement for a 3G network EDGE requires no H/W changes in GSM core networks BSSs must be modifiedEDGE can be introduced in two ways :1) Packet-switched enhancement (called EGPRS)2) Circuit-switched data enhancement (called ECSD). GGRajan
  61. 61. GPRS - EDGE compared Technical Differences - GPRS and EDGETechnology Data Rates Spectrum Services Voice and circuit dataGSM/HSCSD 9.6 to 57.6 kbps 200 kHz services GPRS 171.6 kpbs 200 kHz Packet data services EDGE 473.6 kbps 200 kHz Packet data services GGRajan
  62. 62. GGRajan

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