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Cell Phones and Computers Monica Leclerc Joseph Fasino Nicole Downs History

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cell phones and computers

Cell Phones and Computers

Monica Leclerc

Joseph Fasino

Nicole Downs

slide2

History

Cellular: A type of wireless communication that is most familiar to mobile phones users. It's called 'cellular' because the system uses many base stations to divide a service area into multiple 'cells'. Cellular calls are transferred from base station to base station as a user travels from cell to cell. (Bellis)

the first model
The First Model
  • First concept introduced in 1947
  • Incorporated technology from car phones
  • Purely theoretical
  • No technology existed to support it
the fcc
The FCC
  • The Federal Communications Committee
  • Queried by AT&T for allocation of radio frequencies
  • Supposed to motivate research
  • Suggested business profit capability
  • Granted limited amount
the problem
The Problem
  • The FCC was too wary of the new technology
  • Only allocated enough to sustain 23 conversations in one cell area
  • Not suitable for large profit
  • Inhibited research and progress
slide6
1968
  • FCC reconsiders
  • “if the technology to build a better mobile service works, we will increase the frequencies allocation, freeing the airwaves for more mobile phones”. (Bellis)
  • AT&T and Bell Labs propose theories
  • Still no existing technology
dr martin cooper
Dr. Martin Cooper
  • Researcher for Motorola
  • Credited with inventing the first cellular phone
  • 1973 made the first call to rival Joel Engel, Head Researcher from Bell Labs
  • Motorola first to use cell technology without the use of an automobile
at t follows suit
AT&T Follows Suit
  • 1977 introduced their own patent
  • 1978 tested in Chicago with a trial of over 2,000
how it works
How it works
  • They operate between cells and switch cells as a person moves around.
  • When you make a call on your cell phone, it is wirelessly linked to the telephone network via these towers so your call can be connected.
towers
Towers
  • Each tower, or base station, covers a roughly circular area called a cell
  • This allows different base stations to use the same frequencies, or channels, for communication links as long as a sufficient distance separates them. This is known as frequency re-use, and allows thousands or even hundreds of thousands of mobile telephone users in a metropolitan area to share far fewer channels
making a call
Making a call
  • Transmits the number along with a request for service signal.
  • It then transmits this information on the strongest reverse control channel where the MTSO checks the information and assigns it to a voice channel.
  • The cell site will then open a voice channel and transmit a SAT which is then locked onto the mobile and transmitted back to the cell site.
  • The info is then confirmed and sends a mobile message as either a busy signal or a ringback.
3 generations of mobile technology
3 generations of mobile technology:
  • Analog
  • Digital
  • Smart phones
slide14

Analog System

  • The first generation of mobile technology is the analog cellular system
  • Increase in the number of available channels
  • The cell-phone carrier receives about 800frequencies to use across a city.
  • The carrier chops up the city into cells, each cell is about 10 square miles and are on a giant hexagon grid.
cell grid
Cell Grid
  • Each cell consists of a base tower through which signals are sent and received.
  • Each cell uses 1/7 of the available channels so its frequency is unique and the signals don’t collide.
2g digital transmission
2G Digital Transmission
  • Increase in the number of available channels within a given bandwidth.
  • It compresses your voice into binary information which allows 3-10 digital phones to occupy the space of one single analog call.
  • Frequency shift keying sends data back and forth over AMPS using 2 alternate frequencies,1s and 0s, alternating rapidly between the two to send digital information between the cell tower and the phone.
  • They have a lot of processing power.
sharing technologies 2g 3g
Sharing technologies 2G & 3G
  • Frequency division multiple access (FDMA)
    • Puts each call on a separate frequency.
  • Time division multiple access (TDMA)
    • Assigns each call a certain amount of time on its designated frequency.
  • Code division multiple access (CDMA)
    • Gives each call it’s own unique code and spreads it over the available frequencies
slide18

FDMA

TDMA

CDMA

3g smart phones
3G Smart phones
  • Intended for true multimedia use- referred to as smart phones
  • Smart phones are intended to allow you to use other programs on the phone that you couldn’t use with a standard phone.
  • Increased bandwidth and has transfer rates to accommodate the internet.
  • It contains many cellular technologies but the 3 most common are: Code Division Multiple Access, Wideband Code Division Multiple Access, and Time-division Synchronous Code-division Multiple Access.
slide20

Analog

Digital

Smart phone

taking it apart
Taking it apart
  • Circuit board – brains of the phone
  • Antenna
  • Liquid Crystal Display (LCD)
  • Keyboard
  • Microphone
  • Speaker
  • Battery
circuit board
Circuit board
  • Contains an analog-to-digital and digital-to-analog conversion chip which translates the outgoing audio signal from analog to digital and the incoming signal from digital back to analog.

Front

Back

lcd keypad and other parts
LCD, keypad, and other parts
  • Speaker, microphone and battery backups
  • Thinner, lighter, use less battery power than other displays
microprocessor flash memory
Microprocessor & Flash memory
  • The microprocessor deals with command and control signaling with the base station. It also coordinates the functions of the keyboard and display.
  • The flash memory and ROM chips provide storage for the operating system and customizable phone features.
  • Some phones use internal memory to store info while others use the external memory card.
four main carriers
Four Main Carriers
  • Verizon Wireless
  • T-Mobile
  • Cingular
  • Sprint/Nextel
add ons for phones
Text Messaging

Multimedia Messaging

E-mail

Internet

Instant Messaging

MP3 Player

Maps

News & Weather

Custom Ring Tones

Ring Back Tones

Video Player

Add-ons for Phones