Mobitex is a wireless network architecture that specifies a framework for the fixed equipment necessary to support all the wireless terminals in a packet-switched, radio-based communication system. The three major components of a Mobitex network are the radio base station, the MX switch, and the network management center (NCC). Mobitex was developed in 1984 by Eritel, an Ericsson subsidiary, for the Swedish Telecommunication Administration.
In a Mobitex network, a radio base station, with one or more switches (called MX switches), serves as the transmitter for each single cell (area of coverage) of up to 30 km. The base stations, among them, provide an area of coverage and determine the network capacity. Users of wireless devices, such as mobile phones and personal digital assistants (PDAs), communicate through the base station nearest to them and can move freely from one cell to another.
The use of packet-switching technology for data transmission is less expensive than circuit-switching, which uses a dedicated path for each transmission. Mobitex packets (called MPAKs) are limited to 512 bytes of data. Each packet contains information about its origin and destination, size, type, and sequence within a transmission to ensure that it reaches its destination intact. Because packets can be sent on any route and in any order, they make more efficient use of channel capacity, supporting up to 50 times as many users per channel as a circuit-switched network. At the destination, packets are reorganized into the original transmission format.
MX switches control communication routes to and from base stations and between wireless and fixed devices. Switches may be organized hierarchically into groupings of regional and area switches, all connected by fixed links. The MX switches also act as a gateway to other networks. A single network management center (NCC) takes care of maintenance and operations such as configuration and subscriber administration and billing.
Currently at least twenty-eight Mobitex networks are in operation in twenty-two countries, mostly operating at either 80, 400, or 900 megahertz (MHz). In the US, Mobitex networks generally operate at 900 MHz, while European networks usually operate at 400 MHz. The Mobitex Operators Association (MOA) controls Mobitex specifications; Ericsson manufactures the infrastructure components.