Channel access method

Multiple access (of English. Multiple access ) refers to communications engineering a number of methods for allocation of transmission capacity of a transmission system is among the stations connected to it. In the transmission system may be, for example, a radio channel, a communication satellite or a bus for a Local Area Network ( LAN).

The frequency division multiple access (Frequency Division Multiple Access, FDMA), the stations use separate frequency channels.

The time division multiple access ( Time Division Multiple Access, TDMA ), the message blocks transmitted by a time division method. The token method ( for example token ring) is a TDMA method, wherein the access is in the form of a token, which is passed by a predetermined order of station to station. When competing processes such as Carrier Sense Multiple Access (CSMA ) no access order exists among the attached stations, so that it can be collisions.

Multiple access prior knowledge, the method allows code division ( code division multiple access, CDMA )

Several spatially separated antennas allow spatial multiplexing (space division multiple access, SDMA). The special feature of this method is that the participants neither time nor need to share the frequency, and thus a total of more bandwidth is available for each participant.

See also: multiplexing method, access method (network)

• Communications Engineering