Multiple access

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Multiple access (of Engl. Multiple Access ) referred to in the communications engineering a series of procedures for sharing the transmission capacity of a transmission system among the connected stations. The transmission system can be, for example, a radio channel, a communication satellite or a bus line for a local area network (LAN).

With frequency division multiple access ( FDMA), the stations use separate frequency channels.

When time division multiple access (Time Division Multiple Access, TDMA), the messages are sent in blocks according to a time division multiplexing. The token process (e.g. token ring ) is a TDMA process in which access takes the form of a transmission authorization that is passed on from station to station in a specified sequence. With competition procedures such as Carrier Sense Multiple Access (CSMA) there is no access order among the connected stations, so that collisions can occur.

Multiple access prior knowledge allows the process code division multiplexing (Code Division Multiple Access, CDMA).

Plurality of spatially separated antennas provide spatial multiplexing (Space Division Multiple Access, SDMA). The special thing about this procedure is that the participants neither have to share time nor frequency, and thus more bandwidth is available per participant.

literature

  • Ulrich Freyer: Media technology. Basic knowledge of communications technology - terms - functions - applications, Carl Hanser Verlag, Leipzig 2013, ISBN 978-3-446-42915-4 .
  • Hermann Weidenfeller: Basics of communication technology . Springer Fachmedien, Wiesbaden 2002, ISBN 3-519-06265-8 .
  • Jürgen Lindner: Information transfer. Basics of communication technology. Springer Verlag, Berlin / Heidelberg 2005, ISBN 3-540-21400-3 .
  • Rudolf Nocker: Digital Communication Systems 2. 1. Edition. Friedrich Vieweg & Sohn Verlag, Wiesbaden 2005, ISBN 3-528-03977-9 .

See also

Web links