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Network Information (cont.)
Mobitex Network Technology for the RAM Network
The Mobitex wireless network technology, developed by Eritel in 1984 for Swedish
Telecom, has become an international data communication standard. Now managed
by the Mobitex Operators Association (MOA), which controls the specifications
for this open standard, Mobitex is a secure, reliable, wireless packet switching
network specifically designed for wide-area wireless data communications.
Mobitex networks are deployed on every continent in the world (except Antarctica).
Mobitex is presently available* in Australia, Belgium, Canada, Chile, Finland,
France, Germany, Korea, the Netherlands, Nigeria, Norway, Poland, Singapore,
Sweden, the United Kingdom, and the United States.
Mobitex provides highly reliable, two-way digital data transmission. The network
provides error detection and correction to ensure the integrity of the data being sent
and received, and includes transmission acknowledgment.
The Mobitex network has a hierarchical (or pyramid) network structure. Messages
are routed from sender to receiver along the most direct path possible. Each Mobitex
radio modem is assigned a unique Mobitex Access Number (MAN), and the network
remains constantly aware of the mobile’s location while it is within network coverage.
Each radio cell is served by an intelligent base station. Because intelligence is
distributed throughout the network, data is only forwarded to the lowest network
node common to the sender and the receiver. The base station is thus able to
handle all local traffic in the cell.
The network constantly monitors the location of the mobile users. As a mobile
moves from one area of coverage to another, base stations track its signals, sending
updated mobile location and status information to the network. If the network goes
down at any point in transmission, the message is held until network service is
restored. If the mobile receiver moves outside the coverage area, the base station
holds on to data until coverage is reestablished, thus preventing loss of data and
increasing reliability of transmission.
Mobitex uses a packet switching technique to provide the greatest flexibility in
data transmission. Mobitex packets include information about the origin, destination,
size, type, and sequence of data to be sent, enabling packets to be transmitted
individually, in any order, as traffic permits. Individual packets may travel along
different routes, in any order, without interfering with other packets sent over the
same frequency by different users. At the receiving end, all packets are accounted
for, and reassembled into the original message. Setup time is eliminated and network
connection is instantaneous. As a result, packet-switching makes far more efficient
use of channel capacity, typically allowing 10 to 50 times more users over a radio
channel than a circuit switched network.
* as of April, 1997