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CELLULAR RADIO

CELLULAR RADIO. OBJECTIVE :. Identifying the cellular radio  system  Describes the principles and characteristics of  cellular radio Draw a block of unit moblile communication '  Explain the functions of each block of the mobile communications

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CELLULAR RADIO

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  1. CELLULAR RADIO

  2. OBJECTIVE : • Identifying the cellular radio system •  Describes the principles and characteristics of cellular radio • Draw ablockof unit moblile communication • ' Explain the functions of each block of the mobile communications • Differentiate control channels and voice channels •  Identifying the types and characteristics of the antenna

  3. INTRODUCTION • Cellular Radio Communications System is     a two-way form of communication. • using radio waves • cellular phone can be connected to the telephone system,where it isconnected to the world.

  4. Bell Telephone Company, the AT & T has     create a cellular radio system at the end of the 70s and fully implemented in early 1980. • Known as ‘Advanced Mobile Phone • Service’(AMPS).

  5. MTSO Sel CELLULAR RADIO PRINCIPLES • There are transmitter and receiver where it divides its services to smaller areas called “CELL” • The smaller the radius of a cell, the higher the available bandwidth. So, in highly populated urban areas, there are cells with a radius of a few hundred metres, while huge cells of up to thirty kilometres provide coverage in rural areas. • Each cell consists of a receiver and transmitter with low powercalled 'Radio Base Station' (RBS) .     enable it to provide services  to the user in the coverage of several square kilometers.

  6. Each cell is connected by telephone lines or microwave to the Main Control Center, known as‘Mobile Telephone Switching Office’(MTSO).

  7. CHARACTERISTICS OF CELLULAR RADIO COMMUNICATION SYSTEM • When user moves out of one cell to another cell, they automatic switching system  to the another  RBS. • Recipients in each cell will monitor the signal strength of • the mobile unit. When signal strength falls to a level below the prescribed level, or reference, then it will automatically be switched to a higher level through the nearest RBS.

  8. BASIC COMPONENT OF RADIO CELLULAR COMMUNICATION SYSTEM Unit Mobile : • Is a consumer devices that used      to make and receive calls.

  9. Radio Base Station (RBS): • Is an outside station-guard cells Controller that received instructions from the MTSO. • using the radio channel that      found in every cell including the       voice channels and control channels • Supervise the call which includes monitoring     on speech quality and measurement     on the strength of the voice signal. • Send and receive voice signals and      data from/to consumers. • asan interface between users and systems.

  10. Mobile Telephone Switching Office (MTSO): • A mobile switching center, • as the heart of the system • Perform the switching operation   between cellular networks and public telephone network. • implementing supervisory that determine and updating the locations of mobile units when there is movement from one  cell to cell. • Receive and process datareceived from the RBS include •  the status of mobile units, •  diagnostic data, information for billing, data text and so on. • Implementing the flow to determine the appropriate cells andthe necessary radio channels •  when a call is to be made.

  11. CELLULAR PHONE UNIT

  12. Transmiter Frequency Synthesizer Receiver Logic Unit Cellular Phone Control Unit cellular phone block diagram

  13. TRANSMITTER. • Low-power FM transmitters, frequency range 825MHz to 845MHz. • Has a transmission channel 666 at a distance of 30 kHz each other. • Power  emissions:Mobile radio = 3 WMobile phone = 500 mW

  14. Frequency synthesizer. • To generate the signals for the use of transmitter and receiver • Using a PLL circuit (Phase Locked Loop), where the hablor oscillatorprovide the frequency needed.

  15. receiver. • It is dual-conversionsuperhetrodin. • For each channel, the frequency of transmission and receiving distinguished at a distance of 45 MHz. For example; at a frequency transmission channel is 825.03MHz while the frequency of acceptance for Channel 1 is 870.03 MHz, then the difference between them is 45 MHz. • there are 666 channel • receiver at 30 kHz frequency • range of each other. • Frequency Range= 870.03 MHz to 870.98 MHz.

  16. Logic unit. • Consist of main control circuit for cellular unit • This part is using a microprosessor • (RAM &ROM.) • Contains an additional circuit which is used to interpret signals from the MTSO or cells, and to generatecontrol signals for the transmitter and receiver.

  17. Control Unit . • Consist of speaker, microphone and keypad(touch-tone). • Microprocessor used to control the LCD display and indicators in unit mobile. • microprocessormemory is  capable of storing the frequently called numbers and the automatic dialing system.

  18. Control Channel • Voice Channel 3.3 RADIO channel

  19. Radio Channel • is a two way radio transmission path between the RBS(Radio Base Station) and mobile units • Each channel uses different frequencies for transmission • from the RBS • another transmission from mobile unit to RBS • Use different frequencies to avoid interference or overlapping signal  between transmitter and receiver • Frequency @ the same channel can be used by other cells that are far away from each other

  20. Control Channel Each cell has one (1) control channel that is used only for transmission of data (not voice) Control channel continuously control the flow of data when the mobile unit is ON When the user moves from one cell to another cell, the terminals will be adjusted to a new controlchannel automatically within the operating system. Control channel with the best reception quality will be selected and set of mobile terminals will then be adjusted to this channel until the quality of reception decreases.

  21. Voice Channel Channel which brought conversation signal and used during conversation took place Each cell usually has between 7 to 23 voice channels • Besides bringing the conversation signals, this channelalso route to:*Tone generator SAT (Supervisory Audio Tone)*Data Message*Signaling tone detection*Ringingorder delivery

  22. Antenna At Radio Base Station (RBS), there are TWO(2) types of antenna used:- • Omnidirectional • Directional Antenna is used as a medium of communication between the receiver and transmitter signal.

  23. Omnidirectional Antenna • Antenna has a stability of sending and receiving signals. • Used in less populated areas/rural areas • The coverage area round in shape and every coverage area circle end would overlap between one another • Using only one element.

  24. Coverage area for omnidirectional antenna

  25. Directional Antenna • Antenna that have a directional nature, where transmission is in a certain direction. • Requires three antennas arranged so that each antenna near a corner of 120 coverage • Used in large areas such as urban, town

  26. Directional Antena

  27. COMPARISON

  28. QUIZ 2 • What is the basic component of radio cellular communcation system? • Cellular radio principles is ____________________________________________________________________________________ • Differentiate directional and omnidirectional antenna.

  29. THANK YOU

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