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    GSM-I GSM-I Presentation Transcript

    • Wireless Communication Overview
    • Generic WCS (Wireless Communication System) Switch Base Station Base Station Handset Handset PSTN (Public Switched Telephone Network)
    • Dimensions
      • Carrier/Network Operator
        • Spectrum, PSTN, Internet, …/ISP, Tele Service Provider
      • Protocols/Standards/Systems
        • GSM, AMPS, DECT, PHS, Satellite, ...
      • Network Elements
        • MSC, BSC, BTS, HLR/VLR, IN Elements, ...
      • Services/Applications/Service Platform
        • Voice call, data call, add-on services, ...
      • Handset/Terminals/Smart Phone/Wireless Info Appliance
        • OS, User-Interface, Protocol suite
      • Subscriber Behavior
    • Essential Functions
      • Initialization
        • Register
      • Bursty Data/Signaling Transmission
        • Paging, channel assignment, control signaling, signaling data, ...
      • Mobility
        • Handoff, roaming
    • Wireless Communication Challenges
      • Resources
        • Bandwidth
        • Channel impairment/fading
        • Utilization
      • Mobility
        • Handover, Roaming
        • Location management
        • User access behavior
      • Services
        • Security, Data, ...
      • Terminal Equipment
      • Energy
    • Technology Trend Analog Voice Digital Voice Wireless Multimedia Narrow band Wide band Mobile Phone Mobile Phone + Wireless Data Wireless Info Appliance
    • High-Tier v.s. Low-Tier Systems
      • High-Tier Systems
        • Serving a highly mobile population by means of sophisticated high-power radios
        • Larger cell diameter
        • Higher transmitter power
      • Low-Tier Systems
        • Serving subscribers moving at walking speeds
        • Smaller cell diameter
        • Lower transmitter power
    • A System View
      • High-Tier Systems
        • GSM, DAMPS, CDMA
        • Satellite Systems
      • Low-Tier Systems
        • CT-2, DECT, PHS, PACS
    • Existed System Study (1) GSM (Global System for Mobile Communications)
    • Outline
      • Overview
      • Architecture
      • Numbering & Routing
      • Essential Functions
      • Air Interface
      • Dual Band Network Study
    • GSM Overview
      • GSM
        • Developed by European Community
        • Following ISDN
        • Classified as Tele services and Data services
        • International roaming
        • Radio transmission is based on TDMA (Time Divide Multiple Access)
    • GSM Air Resource Allocation
      • Spectrum
        • Uplink Band
          • 890 - 915 MHz
        • Downlink
          • 935-960 MHz
        • Spacing
          • Duplex spacing: 45 MHz
          • Channel spacing: 200 KHz
          • Total channel number: 124
          • Number of slots per channel
    • GSM Network Components
      • MSC: Mobile Switching Center
      • BSC: Base Station Controller
      • BTS: Base Transceiver Station
      • HLR/VLR: Home Location Register/Visting Location Register
      • SIM Card: Subscriber Identity Module Card
      • Handset
      • Service Center
    • GSM System Architecture Data Terminal HLR/ VLR MSC BSC OMC (Operation & Maintenance Center) Operation Terminal BTS Handset A X.25 A-bis SS7 Network sub-system PSTN Radio sub-system Mobile station UM PSTN
    • SIM Card
      • Subscriber Identity Module
        • Contains
          • phone number (MSISDN)
          • international mobile subscriber identity (IMSI)
          • status of SIM
          • service code
          • authentication key
          • PIN (personal identification code)
          • PUK (personal unlock code)
    • Numbering
      • Mobile Subscriber ISDN Number (MSISDN)
        • Mapping to Mobile Station Roaming Number (MSRN) by HLR
      • International Mobile Subscriber Identify (IMSI)
        • Stored in SIM/HLR
      • Temporary Mobile Subscriber Identity (TMSI)
        • Assigned by VLR, Stored in VLR
      • International Mobile Equipment Identity (IMEI)
        • Unique ID to handset, used by air interface
    • Routing
      • Information resident in MS & SIM
        • IMSI, TMSI, IMEI, and misc. information
      • Routing Information used by Network
        • MSISDN, MSRN
    • Location Information Hierarchy
      • Location Area Hierarchy
      HLR VLR VLR MSC1 MSC2 LA1 HLR: Home Location Register VLR: Visitor Location Register MSC: Mobile Switching Center LA: Location Area MS: Mobile Station LA2
    • Location Information
      • Determines subscriber current location
      • Inform network when subscriber enters a new cell
      • Have to trade-off between paging and location update traffic in system planning
      • Location info contained in
        • Mobile country code, mobile network code, location area code, cell ID
      • Location information is the major burden for network
    • GSM Essential Functions
      • Registration/Location Updating
      • Establishing Communication Link
      • Handover
      • Roaming
    • Registration/Location Updating
      • Inform system the new location of a MS when it changes Location Area (LA)
      • MS continuously measures signal strength to choose the best radio base station
      • The mobile station tunes to a new base station with better signal strength
    • Establish Communication Link
      • Handset request available channel from BTS
      • BTS forward the request to BSC
      • BSC chooses an available channel and inform BTS to activate the channel
      • Information the BSC channel assignment message carries
        • a reference number
        • information about allocated channel (type, frequency, time slot, …)
        • the initial transmission power level to be used by the handset
    • Handover
      • The process of changing cells during a call is called handover in GSM terminology.
      • The measurements to choose the best target cell are performed by MSs and BTSs.
      • The measurements from the MS and the BTS are processed in the BSC. This evaluation process is called locating.
    • Roaming
      • A subscriber moves from the service area of his/her home service company(or network) to another operating company(or network)
    • Wireless Data
    • Computing & Communication Wireless Information Devices Laptop Communicator Smartphone PDA Mobile Phone Communication Computing
    • Wireless Voice & Data Dominate Wireline
    • Typical Internet Service Requirements
      • Long (or continuous) sessions
      • Multiple overlay sessions
      • High degree of burstiness
      • Large span in QoS requirements
      Fundamentally difference from voice telephony
    • Challenges
      • IP network
      • Protocols
      • New data services
      • Generic service platform
      • Information appliances (Handhelds, Palm devices, Smart phones, In-Car systems)
      Lots of bandwidth
    • Today’s GSM Data Services
      • SMS ( Short Message Service)
      • USSD ( Unstructured Supplementary Service Data)
      • HSCSD (High Speed Circuit Switched Data )
      • GPRS (General Packet Radio Services)
      • EDGE (Enhanced Data rates for GSM Evolution)
    • Convergence GSM/IP Network
      • H.323
      • WAP
    • H.323 Architecture Home Service System PSTN Visiting MS HLR MAP SS7 Network Terminal gateway Gatekeeper1 Gatekeeper1 Switch
    • WAP (Wireless Application Platform) Filter Web Server Filter WAP Proxy WAP Proxy Wireless Markup Language Wireless Network
    • Future GSM SIM Card GSM mobile GSM/UMTS mobile UMTS mobile Internet (TCP/IP) BSC (UMTS) UMTS (IMT-2000) Base Station BSC (GSM) GSM Base Station Co-sited GSM+ UMTS Base Station Subsystem GGSN SGSN GPRS+UMTS Landline NW (PSTN/ISDN) Network Subsystem (GSM+UMTS) MSC/HLR (GSM+UMTS) HLR MSC IN service control point SIM
    • GSM Radio Steps to 3rd Generation Development of Radio Technology Evolution of GSM Platform Introduction of 3rd generation radio 2001 - 2002 New multimedia services Mass market cost of service (IMT-2000) 2000 More capacity when needed (GSM384) 1999 Internet-like IP packet services (GPRS) 1998 Landline-like circuit services (HSCSD) 1997 Basic GSM data at 9.6 kb/s
    • Air Interface Protocols
      • SS7
        • Between PSTN and PLMN ( Public Land Mobile Network)
      • X.25
        • BSC and Operation centers
      • A
        • Between BSC and MSC
      • A-bis
        • Between BTS and BSC
      • Um
        • Radio interface between BTS and Handset
    • Air Interface Messages
      • RR: Radio Resource Management Messages
      • MM: Mobility Management Messages
      • CM: Call Management Messages
    • Air Interface--Channels Traffic channels Signaling channel Full-rate TCH/F half-rate TCH/H Frequency correction FCCH Synchronization SCH Broadcast control BCCH Paging PCH Access grant AGCH Random access RACH Stand-alone dedicated control SDCCH Slow associated control SACCH Fast associated control FACCH Two-way Base-to-mobile Two-way
    • Dual Band Network
    • Dual Band Network : GSM 900 & DCS 1800 Air Interface
    • GSM/DCS Network Differences
      • DCS 1800 cells are generally coverage limited
      • GSM 900 cells tend to be capacity limited
      • Implying a need for more DCS 1800 cells to provide similar coverage to a comparable GSM 900
    • Integrate GSM and DCS Networks
      • Integrating 900 and 1800 networks by linking 900/1800 cells to same BSC: An Integrated dual band network
        • Sharing BSC, MSC, and HLR
      • Benefits
        • Reuse existing resources
          • Reuse spectrum means to enlarge the scalability of network and to improve the utilization of spectrum resource
        • Simplify the handoff between networks
        • Flexible and changeable infrastructure