Introduction
Cellular radio provides mobile telephone service by employing a network of cell sites distributed over a wide area. A cell site contains a radio transceiver and a base station controller which manages, sends, and receives traffic from the mobiles in its geographical area to a cellular telephone switch. It also employs a tower and its antennas, and provides a link to the distant cellular switch called a mobile telecommunications switching office. This MTSO places calls from land based telephones to wireless customers, switches calls between cells as mobiles travel across cell boundaries, and authenticates wireless customers before they make calls.
Cellular uses a principle called frequency reuse to greatly increase customers served. Low powered mobiles and radio equipment at each cell site permit the same radio frequencies to be reused in different cells, multiplying calling capacity without creating interference. This spectrum efficient method contrasts sharply with earlier mobile systems that used a high powered, centrally located transmitter, to communicate with high powered car mounted mobiles on a small number of frequenices, channels which were then monopolized and not re-used over a wide area.
Cellular uses a principle called frequency reuse to greatly increase customers served. Low powered mobiles and radio equipment at each cell site permit the same radio frequencies to be reused in different cells, multiplying calling capacity without creating interference. This spectrum efficient method contrasts sharply with earlier mobile systems that used a high powered, centrally located transmitter, to communicate with high powered car mounted mobiles on a small number of frequenices, channels which were then monopolized and not re-used over a wide area.
A larger image of the above and a complete description of same is here
Complex signaling routines handle call placements, call requests, handovers, or call transfers from one cell to another, and roaming, moving from one carrier's area to another. Different cellular radio systems use frequency division multiplexing (analog), time division multiplexing (TDMA), and spread spectrum (CDMA) techniques. Despite different operating methods, AMPS, PCS, GSM, E-TACS, and NMT are all cellular radio. That's because they all rely on a distributed network of cell sites employing frequency re-use. Is your head spinning yet? Let's ease into this cellular discussion by discussing some history first.