Cell phones technology

Wireless phones which receive their signals from towers. A cell is typically the area (several
miles) around a tower in which a signal can be received.
Cell phones provide an incredible array of functions. Depending on the cell-phone model, you
can:
• Store contact information
• Make task or to-do lists
• Keep track of appointments and set reminders
• Use the built-in calculator for simple math
• Send or receive e-mail
• Get information (news, entertainment, stock quotes) from the internet
• Play games
• Watch TV
• Send text messages
• Integrate other devices such as PDAs, MP3 players and GPS receivers
A cell phone is a full-duplex device. That means that you use one frequency for talking and a
second, separate frequency for listening. Both people on the call can talk at once.
Division of a city into small cells allows extensive frequency reuse across a city, so that
millions of people can use cell phones simultaneously. Cell phones operate within cells, and they
can switch cells as they move around. Cells give cell phones incredible range. Someone using a
cell phone can drive hundreds of miles and maintain a conversation the entire time because of the
cellular approach. Each cell has a base station that consists of a tower and a small building
containing the radio equipment.