Cell Phone Working

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By: phanindraforu13 (9 month(s) ago)

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Slide 1: 

Usman Masud 4th semester Uet Peshawar

OUTLINES……. : 

OUTLINES……. What is a cell phone? Cell phone frequencies Cell phone channels Cell phone codes Cellular network technologies Towers

WHAT IS A CELL PHONE : 

WHAT IS A CELL PHONE Extremely sophisticated Radio Telephone was invented by Graham Bell in 1876 Wireless Communications can trace its roots to the invention of radio by Nikolai Tesla in the 1880s

CELL PHONE FREQUENCIES : 

CELL PHONE FREQUENCIES Before Cell Phones there were Radio Telephones. Radio Telephones consisted of one central antenna and about 25 Channels. Central Antenna required a powerful transmitter

CELL PHONE FREQUENCIES : 

CELL PHONE FREQUENCIES The genius of cellular network is the division of city into a number of cells This allows extensive reuse of frequencies across a city To understand the sophistication of cell phone, lets compare it walkie-talkie

CAMPARISON WITH WALKIE-TALKIE : 

CAMPARISON WITH WALKIE-TALKIE Half duplex device One channel Range (1 mile-using 0.25watt transmitter) Full duplex device 1,664 channels or more Range (100 miles or more) WALKIE-TALKIE CELL-PHONE

HALF DUPLEX -VS-FULL DUPLEX : 

HALF DUPLEX -VS-FULL DUPLEX In full-duplex radio, the two transmitters use different frequencies In half-duplex radio, both transmitter use same frequency to communicate

WHAT IS A CELL? : 

WHAT IS A CELL? In typical analog cell phone system, each carrier receives 800 frequencies to use across city carrier chops the city into the cells Each cell is thought of as hexagons on a big hexagonal grids

WHAT IS A CELL? : 

WHAT IS A CELL? Typically sized at about 10 square miles(26 kilometers) Each cell has base station consisting of tower and radio equipment Different cells(non-adjacent )can use the same set of frequencies

CELL PHONE CHANNELS : 

CELL PHONE CHANNELS There are 395 voice channels available per carrier No chance of collision Remaining 42 are used as control channels 56 voice channels are available in a cell, which means in cell 56 people can talk at the same time Mobile telephone switching office(MTSO)

CHANGING THE CELL : 

CHANGING THE CELL

CELL PHONE CODES : 

CELL PHONE CODES All cell phones have special codes associated with them Service identification code(SID): 5 digit code assigned to each carrier Electronic serial number (ESN): 32 bit code programmed into phone by manufacturer Mobile identification number(MIN): 10 digit derived from phone’s no

PURPOSE OF CODES : 

PURPOSE OF CODES Let we switch on the phone, then what happens? It listen for SID on control channel(special frequencies) “no service” message displayed Comparison of SID on control channel with the one programmed in phone. MTSO keeps track of phone’s location in database

CELL PHONE NETWORK TECHNOLOGIES : 

CELL PHONE NETWORK TECHNOLOGIES First Generation (1G) Second Generation (2G) Third Generation (3G)

FIRST GENERATION(1G) : 

FIRST GENERATION(1G) Analog phones: Advanced mobile phone system(AMPS) Drawbacks of analog system (can’t utilize the signal completely)

SECONG GENERATION(2G) : 

SECONG GENERATION(2G) Three common technologies are : Frequency division multiple access(FDMA) Time division multiple access(TDMA) Code division multiple access(CDMA)

SECOND GENERATION(2G) : 

SECOND GENERATION(2G)

THIRD GENERATION(3G) : 

THIRD GENERATION(3G) 3G Technology is intended for true multimedia cell phones(smart phones) Increased bandwidth ,web application, phone based audio, video files etc.. CDMA2000(based on 2G CDMA) WCDMA(wideband CDMA) TD-SCDMA(time division synchronous CDMA)

TOWER : 

TOWER Steel Pole or Lattice Structures of Hundreds of feet tall The Communication Box Grounding

TOWERS : 

TOWERS

PROBLEMS WITH THE CELL PHONES : 

PROBLEMS WITH THE CELL PHONES Internal Corrosion Extreme Heating Cloning