Mobile Computing Glossary

Amateur service:

A radio communications service that licensed operators with no pecuniary interest use for self-training, communications, and technical investigations.

Broadcasting-satellite service (BSS):

A radio communications service in which signals transmitted or retransmitted by satellites are used for direct reception by the general public.

CDMA:

A multiple access scheme by using code sequences as traffic channels in a common radio channel.

Cell Splitting:

A method of increasing capacity by reducing the size of the cell.

Co-Channel Interference Reduction Factor (CIRF):

A key factor used to design a cellular system to avoid cochannel interference.

Downlink:

A radio link from a satellite to a receiving site on earth or in an aircraft.

Duplex Operation:

Operating method in which transmission is possible simultaneously in both directions of a telecommunications channel.

FDMA:

A multiple access scheme by dividing an allocated spectrum into different radio channels.

Feeder Link:

A radio link between an earth station and a satellite, conveying information for a space radio communications service other than fixed satellite service. In the broadcasting-satellite service, all feeder links are uplinks (from the earth to the satellite), but in the mobile-satellite service, feeder links can be both uplinks and downlinks.

Fixed-satellite service (FSS):

A radiocommunication service between earth stations at given fixed positions via one or more satellites.

Fixed service:

A point-to-point radiocommunications service between specific fixed stations on the earth.

Frequency allocation:

A band of radio frequencies identified by an upper and lower frequency limit earmarked for use by one or more of the 38 terrestrial and space radiocommunications services defined by the International Telecommunication Union under specified conditions.

Frequency allotment:

The designation of portions of an allocated frequency band to individual countries or geographical areas for a particular radiocommunication service; for a satellite service, specific orbital positions may also be alloted to individual countries.

Frequency assignment:

Authorization given by a nation's government for a station or an operator in that country to use a specific radio frequency channel under specified conditions.

Frequency reuse factor (K):

A number based on frequency reuse to determine how many channels per cell.

Geostationary satellite orbit (GSO):

A circular orbit approximately 35,900 km above the earth, in the plane of the earth's equator, in which a satellite revolves around the earth in the same time that the earth rotates on its axis; thus the satellite appears approximately stationary over one point on the earth.

Half-Duplex Operation:

Operating method in which transmission is possible in both directions, but only in one direction at a time.

Handoff:

A frequency channel will be changed to a new frequency channel as the vehicle moves from from one cell to another without the user's intervention.

Land Mobile Station:

A mobile station in the land-mobile service capable of surface movement within the geographical limits of a country or continent.

Land-Mobile Service:

A mobile service between base stations and land-mobile stations, or between land-mobile stations.

Land-Mobile-Satellite Service:

A mobile satellite service in which mobile earth stations are located on land.

Low earth orbit (LEO):

Any orbit around the earth substantially below the geostationary satellite orbit, generally below the geostationary satellite orbit, generally within several hundred km above the earth's surface and usually inclied to the equatorial plane.

Mobile Cellular Systems:

A high capacity system operating at 800-900 MHz using a frequency reuse scheme for vehicle and portable telephone communications.

Mobile Service:

A radiocommunication service between mobile and fixed stations, or between mobile stations. Depending on whether one or more of the earth stations are on land, sea, or air, the service would be called land mobile, maritime mobile, or aeronautical mobile.

Mobile-Satellite Service (MSS):

A service that links mobile earth stations with base stations and with one another via one or more satellites.

Mobile Station:

A station in the mobile service intended to be used while in motion or during halts at unspecified points.

Radiocommunications:

Telecommunications using radio waves.

Simplex Operation:

Operating method in which transmission is made possible alternatively in one direction of a telecommunications channel, for example, by means of manual control.

Uplink:

A radio link from a site on the earth or from an aircraft to a satellite.