Channel (communications)
|
|
Channel, in communications (sometimes called communications channel), refers to the medium through which information is transmitted from a sender (or transmitter) to a receiver. In practice, this can mean many different methods of facilitating communication, including:
- A connection between initiating and terminating nodes of a circuit.
- A single path provided by a transmission medium via either
- physical separation, such as by multipair cable or
- electrical separation, such as by frequency- or time-division multiplexing.
- A path for conveying electrical or electromagnetic signals, usually distinguished from other parallel paths.
- The portion of a storage medium, such as a track or a band, that is accessible to a given reading or writing station or head.
- In a communications system, the part that connects a data source to a data sink.
- A specific radio frequency or band of frequencies, usually in conjunction with a predetermined letter, number, or codeword, and allocated by international agreement. For example 802.11b consists of unlicensed channels 1-13 from 2412MHz to 2484MHz in 5MHz steps.
- In particular, a television channel. Examples include North American TV Channel 2 = 55.25MHz, Channel 13 = 211.25MHz.
- A room in the Internet Relay Chat (IRC) network, in which participants can communicate with each other.
Details of channel implementations
In wireless communications, the channel is often modeled by a random attenuation of the transmitted signal, followed by additive noise. The attenuation captures the loss in signal power over the course of the transmission, and the noise in the model captures external interference and/or electronic noise in the receiver. Hence, depending on the application, the mathematical model for the communication system includes a model for the distortion introduced by the transmission medium, and termed the communication channel, or channel for short.
Types of communications channels
See also
- interference
- baseband
- Claude Shannon
- Information theory
- Shannon capacity
- Shannon-Hartley law
- Binary symmetric channel
de:Kommunikationskanal nl:Communicatie-kanalen pl:Kanał komunikacji pt:Camada de transporte