MOBILE COMMUNICATION SYSTEM

Mobile Communication is a wireless communication technique that use radio waves to carry signals and messages across distances.Cellular radio telephones system or mobile communication system is a mode of wireless communication system.
Principle of wireless communication
Wireless communication begin with a message that is converted into an electronic signal by a device called a transmitter.Analog transmitter modulates radio wave to carry the electronic signal THROUGH SPACE,WHEREAS DIGITAL TRANSMITTER ENCODES ELECTRONIC SIGNALS BY CONVERTING MESSAGES INTO A BINARY CODE,THE SERIES OF ZEROS AND ONES.THE ENCODED ELECTRONIC SIGNAL IS THEN SENT AS A RADIO WAVE.DEVICES KNOWN AS RECEIVERS DECODE OR DEMODULATES THE RADIO WAVES AND REPRODUCE THE ORIGINAL MESSAGE OVER A SPEAKER.
CELLULAR RADIO TELEPHONES,ALSO KNOWN AS CELL PHONES COMMUNICATE BY SENDING RADIO SIGNALS TO A CELL TOWER.EACH CELL TOWER HAS A CERTAIN RANGE WITHIN WHICH IT CAN RECEIVE THE RADIO SIGNALS.THE RANGE OF EACH TOWER OVERLAPS WITH THAT OF ANOTHER TOWER SO AS A MOBILE CELL PHONE USER TRAVELS ,COMMUNICATION IS UNINTERRUPTED.TO COMMUNICATE WITH THE USER OF A WIRED TELEPHONE,THE CELL PHONE RADIO SIGNALS ARE ROUTED FROM A CELL TOWER TO A MOBILE SWITCHING CENTRE,WHICH IN TURN ROUTES THE SIGNALS TO THE TELEPHONE COMPANY.THE SIGNALS THEN TRAVELS OVER TELEPHONE LINES TO REACH A WIRED TELEPHONE.
CELL PHONES COMBINE THEIR PORTABLE RADIO CAPABILITY WITH THE WIRED OR WIRED BASED TELEPHONE NETWORK TO PROVIDE MOBILE USERS WITH ACCESS TO THE REST OF THE PUBLIC TELEPHONE SYSTEM USED BY NON MOBILE CALLERS.
AN EARLY FORM OF RADIO TELEPHONE COMMUNICATED WITH A SINGLE POWERFUL ANTENNA WITHIN A GIVEN GEOGRAPHICAL OR METROPOLITAN AREA.THIS LARGE ANTENNA WAS WIRED TO THE TELEPHONE SYSTEM WITH ONLY ONE ANTENNA FOR ALARGE METRO AREA,THIS LIMITED THE NUMBER OF FREQUENCIES THAT COULD BE USED,BECAUSE RADIO TELEPHONE FREQUENCIES WOULD OFTEN OVERLAP AND CAUSE INTERFERENCE.AS A RESULT,ONLY A LIMITED NUMBER OF SIMULTANEOUS CALLS SHOULD BE HALDLED,ONLY A SMALL BLOCK OF CHANNELS COULD BE GENERATED OVER THE AVAILABLE RADIO SPECTRUM ALLOCATED FOR THE SERVICE.
MODERN CELLULAR TELEPHONES USE A NETWORK OF SEVERAL SHORT-RANGE ANTENNAS KNOWN AS TOWERS THAT CONNECT TO THE TELEPHONE SYSTEM.BECAUSE THE ANTENNAS HAVE A SHORTER RANGE AND COVER A SMALLER AREA,OFTEN AS SHORT AS 1.5 TO 2.5KM(1.0 TO 1.5MI),FREQUENCIES CAN BE REUSED A SHORT DISTANCE AWAY WITHOUT OVERLAPPING AND CAUSING INTERFERENCE.

CELL PHONE TOWERS PICK UP REQUESTS FROM CELL PHONES FOR A DIAL TONE AND ALSO DELIVER INBOUND CALLS TO THE APPROPRIATE CELL PHONES DELIVER CALLS TO PEOPLE USING REGULAR TELEPHONES ON THE WIRE BASED SYSTEM.TO DO ANY OF THESE THINGS,THE CELL PHONE MUST HAVE A SINGULAR IDENTITY THAT CAN BE RECOGNIZED BY COMPUTERS HOUSED IN A CENTRAL MOBILE TELEPHONE SWITCHING OFFICE (MTSO).WHEN A CELL PHONE IS TURNED ON ,IT CONNECTS BY RADIO WVES TO THE NEAREST CELL TOWER (TOWER RECEIVING THE STRONGEST SIGNAL).THE CELL TOWERS ARE SPACED SO THEIR RECEIVING RANGES SLIGHTLY OVERLAP.THIS CONTINUOUS CONTACT MAKES IT POSSIBLE FOR THE MTSO TO TRANSFER A CALL FRON TOWER TO TOWER AS A MOBILE CELL PHONE USER (IN MOVING VEHICLE)MOVES FROM ONE CELL AREA TO ANOTHER.