Cell Phones and Computers Monica Leclerc Joseph Fasino Nicole Downs
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 • First concept introduced in 1947 • Incorporated technology from car phones • Purely theoretical • No technology existed to support it
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 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
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 • 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 • 1977 introduced their own patent • 1978 tested in Chicago with a trial of over 2,000
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 • 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 • 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: • Analog • Digital • Smart phones
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 • 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 • 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 • 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
FDMA TDMA CDMA
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.
Analog Digital Smart phone
Taking it apart • Circuit board – brains of the phone • Antenna • Liquid Crystal Display (LCD) • Keyboard • Microphone • Speaker • Battery
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 • Speaker, microphone and battery backups • Thinner, lighter, use less battery power than other displays
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 • Verizon Wireless • T-Mobile • Cingular • Sprint/Nextel
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