Chapter 9 existing wireless systems 2g gsm system
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Chapter 9: Existing Wireless Systems: 2G, GSM System. Associate Prof. Yuh-Shyan Chen Dept. of Computer Science and Information Engineering National Chung-Cheng University. Introduction. Global System for Mobile communication or Groupe Speciale Mobile (GSM) communication

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Chapter 9: Existing Wireless Systems: 2G, GSM System

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Chapter 9 existing wireless systems 2g gsm system

Chapter 9:Existing Wireless Systems:2G, GSM System

Associate Prof. Yuh-Shyan Chen

Dept. of Computer Science and Information Engineering

National Chung-Cheng University


Introduction

Introduction

  • Global System for Mobile communication or Groupe Speciale Mobile (GSM) communication

    • Initiated by European Commission

    • Second-generation mobile cellular system

      • Aimes at developing a Europe-wide digital cellular system

    • Created in 1982 to have a common European mobile telephone standard that would formulate specifications for a pan-European mobile cellular radio system operating at 900 MHz

    • The main objective of GSM is to remove any incompatibility among the systems by allowing the roaming phenomenon for any cell phone


Introduction1

Introduction

  • It also supports speed transmissions between MSs, emergency calls, and digital data transmission

  • Specific functions of different constituents are as follows

    • Base Station Controller (BSC):

    • Mobile Switching Center (MSC):

    • Authentication Center (AC):

    • Equipment Identity Register (EIR):


  • Gsm infrastructure

    GSM infrastructure


    Frequency bands and channels

    Frequency Bands and Channels

    • GSM has been allocated an operational frequency from 890 MHz and 960 MHz

      • MSs employ 890 MHz to 915 MHz

      • BS operates in 935 MHz and 960 MHz

    • GSM follows FDMA and allows up to 124 MSs to be serviced at the same time

      • The frequency band of 25 MHz is divided into 124 frequency division multiplexing (FDM) channels, each of 200 kHz (Fig. 10.9)

      • A guard frame of 8.25 bits is used between any two frames transmitted either by the BS or the MS


    Frequency band used by gsm

    Frequency band used by GSM


    Gsm uses a variety of multiplexing techniques

    GSM uses a variety of multiplexing techniques

    • GSM uses a variety of multiplexing techniques to create a collection of logical channels

    • Three control channels are used for broadcasting some information to all MSs

      • Broadcast control channel (BCCH)

      • Frequency correction channel (FCCH)

      • Synchronization channel (SCH)


    Channel in gsm

    Channel in GSM


    Chapter 9 existing wireless systems 2g gsm system

    Cont.

    • Three common control channels are used for establishing links between the MS and the BS

      • Random access channel (RACH):

        • Used by the MS to transmit information regarding the requested dedicated channel from GSM

      • Paging channel:

        • Used by the BS to communicate with individual MSs in the cell

      • Access grant channel:

        • Used by the BS to send information about timing and synchronization


    Chapter 9 existing wireless systems 2g gsm system

    Cont.

    • Three dedicated control channels are used

      • Slow associated control channel (SACCH):

      • Stand-alone dedicated control channel (SDCCH):

      • Fast associated control channel (FACCH):


    Frames in gsm

    Frames in GSM

    • GSM system uses the TDMA scheme with a 4.615 – ms long frame

      • Dividing into eight time slots each of 0.557 ms

      • Each frame measured in terms of time is 156.25 bits long, of which 8.25 period bits are guard bits for protection

      • The 148 bits are used to transmit the information

      • The frame contains 26 training bits allow the receiver to synchronize itself

      • Many such frames are combined to constitute multiframes, superframes, and hyperframes


    Frame structure of tdma

    Frame structure of TDMA


    Identify numbers used by a gsm system

    Identify Numbers used by a GSM System

    • International Mobile Subscriber Identity (IMSI)


    Format of imsi

    Format of IMSI


    Chapter 9 existing wireless systems 2g gsm system

    Cont.

    • Subscriber Identify Module (SIM)

      • Every time the MS has to communicate with a BS, it must correctly identify itself.

      • A MS does this by storing the phone number, personal identification number for the station, authentication parameters, and so on in the SIM card

      • Smart SIM cards have a flash memory

      • The main advantage of SIM is that is supports roaming with or without a cell phone, also called SIM roaming

  • Mobile System ISDN (MSISDN)


  • Format of msisdn

    Format of MSISDN


    Chapter 9 existing wireless systems 2g gsm system

    Cont.

    • Location Area Identify (LAI)

      • The GSM service area is usually divided into a hierarchical structure that facilitates the system to access any MS quickly

      • Each PLMN is divided into many MSCs

      • Each MSC typically contains a VLR to tell the system if a particular cell phone is roaming

      • If it is roaming, the VLR of the MSC in which the cell phone is reflects the fact

      • Each MSC is divided into many location areas (LAs)

      • A location area is a cell or a group of cells and is useful when the MS is roaming in a different cell but the same LA


    Chapter 9 existing wireless systems 2g gsm system

    Cont.

    • Since any LA has to be identified as the part of the hierarchical structure

    • The identifier should contain the country code, mobile network code, and LA code


    Gsm layout

    GSM layout


    Chapter 9 existing wireless systems 2g gsm system

    Cont.

    • International MS Equipment Identity (IMSEI)


    Format of imsei

    Format of IMSEI


    Chapter 9 existing wireless systems 2g gsm system

    Cont.

    • MS Roaming Number (MSRN)


    Format of msrn

    Format of MSRN


    Layout planes and interfaces of gsm

    Layout, Planes, and Interfaces of GSM


    Interface of gsm

    Interface of GSM


    Chapter 9 existing wireless systems 2g gsm system

    Cont.

    • The GSM system can be divided into five planes

      • OAM

      • CM

      • MM

      • RR

      • Physical


    Functional planes in gsm

    Functional planes in GSM


    Authentication

    Authentication

    • Authentication is done with the help of a fixed network that is used to compare the IMSI (International Mobile Subscriber Identity) of the MS reliably


    Authentication process in gsm

    Authentication process in GSM


    Handoff in gsm

    Handoff in GSM

    • Intracell/intra-BTS handoff

    • Intercell/intra-BSC handoff

    • Inter-BSC/intra-MSC handoff

    • Inter-MSC handoff


    Inter msc handoff

    Inter-MSC handoff


    Personal communication service pcs

    Personal Communication Service (PCS)

    • PCS employs an inexpensive, lightweight, and portable handset to communicate with a PCS BS

    • The PCS is classified into high-tier and lower-tier standards

    • High-tier system includes high-mobility units with large batteries

      • An MS in a car

    • Low-tier system includes system with low mobility, capable of providing high-quality portable communication service over a wide area

    • The PCS lower-tier standards based on PACS (Personal Access Communication Systems) and DECT (Digital European Cordless Telecommunication) are given in Table 10.6.


    Fcc view of pcs

    FCC view of PCS


    Pcs high tier standards

    PCS High-Tier Standards


    Pcs low tier standards

    PCS Low-Tier Standards


    Chronology of pcs development

    Chronology of PCS Development

    • CT2 (Cordless Telephone)

      • Using FDMA with a speed rate of 32 kbps using Adaptive Differential Pulse Code Mudulation (ADPCM)

      • The transmitter data rate is 72 kbps

      • Uses TDD, which allows BS and MS share one channel

      • D is called D-channel which includes 4 bits of control information

  • DECT (Digital European Cordless Telecommunication)


  • Ct2 tdd slot first generation

    CT2 TDD Slot (First Generation)


    Dect digital european cordless telecommunication

    DECT (Digital European Cordless Telecommunication)

    • The second-generation cordless telephone system

    • DECT operates on frequencies ranging from 1880 MHz to 1900 MHz

    • Uses ADPCM with 32 kbps speed rate

    • Uses TDD with two frames with 10-ms periods

    • Supports both voice and data transmission


    Dect tdd slot second generation

    DECT TDD Slot (Second Generation)


    Bellcore view of pcs

    Bellcore View of PCS

    • The Bellcore view of PCS is based on five different service provided between the Bellcore client company (BCC), BCC network, and the PCS wireless provider network

      • PCS access service for networks (PASN)

        • A connection service to and from the PCS service provider (PSP)

      • PCS access service for controllers (PASC)

        • A service for use with PCS wireless provider (PWP) across radio channels and some type of automatic link transfer capability


    Bellcore view of pcs1

    Bellcore View of PCS

    • PCS access service for ports (PASP)

      • An interface into PWP

    • PCS access service for data (PASD)

      • A database information transport service

    • PCS access service for external service providers (PASE)

      • Is used to support specialized PCS service like voice mail and paging


    Bellcore pcs architecture

    Bellcore PCS Architecture

    Signaling

    System 7

    Radio Port

    Radio Port

    Control Unit

    Operation, Administration,

    & Maintenance


    Description of the pcs air interface forward tdma frame for pcs

    Description of the PCS Air Interface:Forward TDMA Frame for PCS


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