Cellular Networks and Access to Public Networks

Cellular networks consist of cellular base stations, mobile telephone switching offices (MTSO), and mobile communication devices. Each base station contains a radio transceiver and controller and provides radio communication to the mobile units located in its cell. The cells are arranged in a honeycomb pattern in order to provide local, regional, or national cellular coverage. The MTSO links calls together using traditional copper, fiber optic, or microwave technology and acts as a central office excha nge allowing users to place a call on the local and long distance public telephone systems. It also allows mobile communication devices in the cell to dial out and alerts devices in the cell of incoming calls. The MTSO continuously monitors the quality of the communications signal and transfers the call to another base station which is better suited to provide communication to the mobile device.
The mobile communication devices consist of hand held phones, car phones, notebook computers, personal digital assistants, pen-based computers, palm-top computers, and portable data collection devices. Since only two percent of the cellular traffic is d ata, the most popular mobile units are cellular telephones (Gareiss, 1995). When these mobile units communicate to the network, they must register with the system by subscribing to a carrier service. Most carrier services have arrangements with other pr oviders allowing users to roam. Roaming occurs when the mobile unit is outside the coverage of their cellular service provider and an alternative cellular provider places the call.
Cellular technology extends the bounds of a corporation's existing telecommunications infrastructure by connecting mobile units to the public network operated by the local exchange or long distance carriers. The cellular users have special features an d functions specific to cellular customers but they can also use the features and functions of the public phone systems. This allows cellular technology to be flexible enough to take advantage of features and functions of almost any public or private net work.

from :http://scis.nova.edu/~raciti/cellular.html