Mobile communication


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An introduction of mobile communication technology.

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Mobile communication

  1. 1. Wireless Communication is a medium totransfer information to different locationsseparated by distances or conditions whichdo not allow wired communication to beapplicable.
  2. 2. Wireless Communication is a medium totransfer information to different locationsseparated by distances or conditions whichdo not allow wired communication to beapplicable.
  3. 3. The worlds first, wireless telephone conversation occurred in 1880, whenAlexander Graham Bell and Charles Sumner Tainter invented andpatented the photophone, a telephone that conducted audioconversations wirelessly over modulated light beams
  4. 4. The amount of spectrum allocated to thesedifferent uses differs by country andfrequency band. For example, in the U.K. 88MHz to 3GHz TV Broadcasting 17% Other 15% Aeronautical radar Defence 23% 24% GSM 17% GSM 0.5% 4%
  5. 5. Operational amplifiersEncodersDecodersInput and display to interact with the device Basic mobile phone services to allow users to make calls and send text messages.
  6. 6. A good way to understand the sophistication of a cellphone is to compare it to a CB radio or a walkie- talkie.
  7. 7. In a cellular radio system, a land area to besupplied with radio service is divided intoregular shaped cells Each of these cells is assigned multiple frequencies which have corresponding radio base stations.
  8. 8. The group of frequencies can be reused inIn the practice of cell planning, cells are notother cells, provided that the same frequencies as in the theoretical studies. hexagonalare not reused in adjacent neighboring cells as methods are being used for optimised Computerthat would cause co-channel interference.planning of base station location and cell frequencies. Source: Siemens TORNADO D Cellular Planning Tool
  9. 9. In a cellular system, as the distributed mobiletransceivers move from cell to cell during anongoing continuous communication, switching fromone cell frequency to a different cell frequency isdone electronically without interruption and withouta base station operator or manual switching.
  10. 10. The Base Transceiver Station (BTS)The Base Station Controller (BSC)The Transcoding Rate and Adaptation Unit(TRAU)
  11. 11. The Base Station Controller isthe BSS’s centre of intelligence.It consists of:A switching array whichconnects several BTSs to theMSCA data bank in which thequality and availability of theradio resources are store andthe status of the BSS-Hardwareis dynamically watchedA central processing unit(CPU) which makes thehandover decisions.
  12. 12. Mobile Services Switching Centre MSCGateway Mobile Services Switching CentreGMSCHome Location Register HLRVisitor Location Register VLREquipment Identity Register EIR
  13. 13. Mobile Services Switching Centre MSCIt takes over the exchange of channels and controls handover betweenseveral MSC areas. The MSC also adapts protocols between CallControl.Gateway Mobile Services Switching Centre GMSCOnly the GMSC is able to create a connection from a PLMN toanother network. The GMSC initiates a search for the calledsubscriber using his Home Location Register.Home Location Register HLR The first two digits of the mobile directory are the number of the HLR where the mobile subscriber is stored.
  14. 14. Visitor Location Register VLR A VLR stores subscription data for those subscribers currentlysituated in the service area of the corresponding MSC. A VLR function isintegrated with every MSC.The following information is stored in the VLR International Mobile Subscriber Identity IMSI Temporary Mobile Subscriber Identity TMSI Equipment Identity Register EIREvery MS possesses an International Mobile Equipment Identity IMEI. *#06#
  15. 15. Worlds most popular standard for telephonysystems.Cell sizes in a GSM network—macro, micro, pico, femto and umbrella cells.The modulation used in GSM is Gaussianminimum-shift keying (GMSK)Most 2G GSM networks operating in the900 MHz or 1800 MHz bands
  16. 16. Frequencies are divided into timeslots for individualphones to use. Eight full-rate or sixteen half-rate speechchannels per radio frequency. The channel data rate for all 8 channels is 270.833 kbit/s, and the frame duration is 4.615ms. 2 watts in GSM850/900. 1 watt in GSM1800/1900.
  17. 17. Half Rate (6.5 kbit/s)Full Rate (13 kbit/s).These used a system based upon linear predictive coding (LPC).EFR was refactored into a variable-ratecodec called AMR-Narrowband,Commonly known as a SIM card.The SIM is a detachable smartcard containing the userssubscription information
  18. 18. Multiple CDMA handsets share a specificradio channel. The signals are separatedby using a pseudo noise codeCDMA is a spread spectrum multipleaccess technique.
  19. 19. Higher capacityImproves voice qualitySoft-handoffs „Less power consumption (6-7 mW) Drawbacks of CDMA Cellular Self-jamming Near-far problem Soft handoff more complex than hard handoff used in FDMA and TDMA schemes