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ساختار شبکه GSM و عملكرد هر كدام از اجزاي آن

ساختار شبکه GSM و عملكرد هر كدام از اجزاي آن. ساختار شبکه Mobile بايد به صورتي باشد كه : در هر مکانی به مشترک سرويس دهی شود با هر سرعتی مشترک سرويس دهی شود مکان مشترک مشخص شود هويت مشترک مشخص شود سرويسی مورد درخواست مشترک ارايه شود با تمام شبكه هاي ديگر ارتباط و تبادل داشته باشد.

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ساختار شبکه GSM و عملكرد هر كدام از اجزاي آن

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  1. ساختار شبکه GSM و عملكرد هر كدام از اجزاي آن

  2. ساختار شبکه Mobile بايد به صورتي باشد كه : • در هر مکانی به مشترک سرويس دهی شود • با هر سرعتی مشترک سرويس دهی شود • مکان مشترک مشخص شود • هويت مشترک مشخص شود • سرويسی مورد درخواست مشترک ارايه شود • با تمام شبكه هاي ديگر ارتباط و تبادل داشته باشد

  3. Control flow NMS PLMN User data flow PSTN NSS BSS PSPDN CSPDN ISDN M S GSM Subsystem & relationships Access part Core part

  4. GSM Architecture

  5. GSM GSM System Architecture HLR/ VLR UM Handset A-bis A SS7 BSC MSC X.25 PSTN BTS OMC (Operation & Maintenance Center) Operation Terminal Data Terminal SIM card Mobile station Radio sub-system Network sub-system PSTN

  6. The MS (Mobile Station) is a combination of terminal equipment and subscriber data. ME (Mobile Equipment ) SIM( Subscriber Identity Module) Mobile Station (MS) ME+ SIM  MS

  7. SIM card • Uniquely Associated To A User • Stores User And Location Addresses • Supports Authentication And Encryption Mechanisms • Contains Personal Data • list of subscribed services • RAM for user directory, SMS

  8. Smart Card Anatomy

  9. پایه های سیم کارت • پايه Vcc • پايهGND • پايه CLK • پايهRST • پايهI/O • پايه Vpp

  10. Microprocessor Cards • Typical specification • 16 bit CPU • 128 K ROM • 1 K bytes RAM • 32K EEPROM • Smart Card Technology • Based on ISO 7816 defining • Card size, contact layout, electrical characteristics • I/O Protocols: byte/block based • File Structure

  11. میکروکنترلراجزای تشکیل دهنده

  12. Stored data in SIM Card

  13. Stored data in SIM Card

  14. استانداردهای مربوط به سیم کارت • GSM • GSM 11.11 (SIM interface spec) • GSM 11.14 (SIM toolkit) • GSM 03.48 (OTA communication) • GSM11.17(SIM TEST APPROACH) • ISO • ISO 7810 • ISO 7816

  15. Mobile station power classes Usual Classes

  16. BSS:Base StationSubsystem • BTS )Base Transceiver Station(----Transmitter, receiver and antennas • BSC )Base Station Controller(----Management of several BTS • TC( Transcoder )---Adapt Bit rate to send MSC

  17. BTS • provides GSM radio coverage within a cll • comprises radio transmitting and receiving equipment (including antennas) • associated signal processing • implementation of radio related operations: • slow frequency hopping (SFH) • discontinuous transmission (DTX) • Ciphering • power control. • Synchronization between MSs • Management of Signaling line

  18. GSM BTS Power Classes

  19. BSC • A small switch with enhanced processing capability. • Its responsibilities include: • co-ordination and control of a number of BTSs • traffic concentration • low level switching operations • network management interface to all radio elements • radio channel management • handover between BTSs within its domain • scheduling of paging request • passing system information e.g. LAI (Location Area Identity) to BTSs for onward transmission • queuing • control of radio related operations: slow frequency hopping (SFH); discontinuous transmission (DTX); ciphering and power control

  20. BSC Transmission between BSC and BTS Point to point connection Multi drop chain Multi drop loop

  21. Transcoder • Speech Coding is used to enable the efficient transmission at 13 Kbps or 6.5 Kbps • service transcoding, changing air interface rates to network rates e.g. converting speech from 13 kbit/s to 64 kbit/s • 3 kbit/s is used for inband signaling • TC can be located at BSC or MSC • If is located near MSC , it can be multiplexed 4 lines in one PCM signals and increase efficiency of transmission

  22. Main task Call control Routing Locating Mobility management Signalling to other network NSS - Network and Switching Subsystem

  23. NSS –Elements • MSC)Mobile Switching Centre-----(Management of all connections • HLR)Home Location Register(-----Associated to each PLMN • VLR)Visitor Location Register-----(Associated to each MSC • GMSC)Gateway MSC MSC-----( providinginterconnection to other networks • AUC : Authentication Center----provide security of network • EIR : Equipment Identity Register---provide absolute information of user

  24. MSC (mobile switching center) • Switching functions • Additional functions for mobility support • Interworking functions via Gateway MSC (GMSC) • Integration of several databases Specific functions of a MSC • Switching of 64 kbit/s channels • Paging and call forwarding • Termination of SS7 (signaling system no. 7) • Mobility specific signaling • Location registration and forwarding of location information • Support of short message service (SMS) • Generation and forwarding of accounting and billing information

  25. Visitor Location Register (VLR) • Local database: • Data about all users currently in the domain of the VLR • Includes roamers and non-roamers • Associated to each MSC • Responsibilities of the VLR include: • Executing supplementary service programs (outgoing calls barred) • Initiating authentication and ciphering • Initiating paging • Mapping of various identities (MSISDN, IMSI, TMSI, MSRN) • Passing location information to HLR

  26. Gateway MSC (GMSC) • Connects mobile network to a fixed network, e.g. Entry point to a PLMN • Request routing information from the HLR and routes the connection to the local MSC

  27. Home Location Register (HLR) • central master database • data from every user that has subscribed to the operator, includes: • subscriber data • IMSI - International Mobile Subscriber Identity • list of subscribed services with parameters and restrictions • location data • current MSC/VLR address • Responsibilities of the HLR include: • management of service profiles • mapping of subscriber identities (MISDN, IMSI) • supplementary service control and profile updates • execution of supplementary service logic e.g. incoming calls barred. • passing subscription records to VLR

  28. Authentication Center (AuC) • Associated to HLR • Search key: IMSI • Supports authentication and encryption mechanisms • Ki - subscriber secret authentication key • A3 - authentication algorithm • A8 - cipher key generation algorithm

  29. Equipment Identity Register (EIR) • stores mobile stations IMEI (International Mobile Equipment Identity) • white list - mobile stations allowed to connect without restrictions • black list - mobile stations locked (stolen or not type approved) • gray list - mobile stations under observation for possible problems

  30. Network Management Subsystem : NMS • Operation & management Center (OMC) Control of the radio and networksubsystems • Event & Fault Management • Configuration management • Performance Management

  31. Event & Fault Management

  32. Maintain up to date information about network Management of radio network Software & hardware management Security management Configuration management

  33. Collect date and measurement from BSC and MSC calculate the KPI Key Performance Indicator Compare the network with desire performance Performance management

  34. Application Service Centers • Short Message Service Center (SMSC) • provide short message services • usually connect to MSC • Unstructured Supplementary Service Data Center (USSDC) • provide USSD service in the form of *ID*ID*info# • usually connect to HLR

  35. GSM Services GSM Services Basic Services Supplementary Services TeleServices Bearer Services

  36. GSM TeleServices

  37. Bearer Service • Give the subscriber the capacity required to transmit appropriate signals between certain access points • Asynchronous data • Synchronous data • Packet switched assembler/ disassembler access • Alternate speech and data

  38. Services Supplementary Services: Advice of charge-AOC Alternate Line Services (ALS)-personal or business Barring of all incoming calls-BAIC Barring of all Incoming calls when roaming outside the HPLMN Barring of Incoming Calls when abroad Barring of outgoing calls-BOC Barring of outgoing International Calls-BOIC Barring of outgoing International calls excluding those directed to the HPLMN country Call forwarding on mobile subscriber busy-CFB Call forwarding on no answer-CFNA Call forwarding unconditional -CFU Call hold Call Waiting-CW

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