Carrier Sense Multiple Access

Carrier Sense Multiple Access (CSMA) is a probabilistic Media Access Control (MAC) protocol in which a node verifies the absence of other traffic before transmitting on a shared transmission medium, such as an electrical bus, or a band of the electromagnetic spectrum.

"Carrier Sense" describes the fact that a transmitter uses feedback from a receiver that detects a carrier wave before trying to send. That is, it tries to detect the presence of an encoded signal from another station before attempting to transmit. If a carrier is sensed, the station waits for the transmission in progress to finish before initiating its own transmission. In other words, CSMA is based on the principle "sense before transmit" or "listen before talk".

"Multiple Access" describes the fact that multiple stations send and receive on the medium. Transmissions by one node are generally received by all other stations using the medium.

Read more about Carrier Sense Multiple Access:  CSMA Access Modes

Famous quotes containing the words carrier, sense, multiple and/or access:

    “Because language is the carrier of ideas, it is easy to believe that it should be very little else than such a carrier.”
    —Louise Bogan (1897–1970)

    “The business of the law is to make sense of the confusion of what we call human life—to reduce it to order but at the same time to give it possibility, scope, even dignity.”
    —Archibald MacLeish (1892–1982)

    “Creativity seems to emerge from multiple experiences, coupled with a well-supported development of personal resources, including a sense of freedom to venture beyond the known.”
    —Loris Malaguzzi (20th century)

    “The last publicized center of American writing was Manhattan. Its writers became known as the New York Intellectuals. With important connections to publishing, and universities, with access to the major book reviews, they were able to pose as the vanguard of American culture when they were so obsessed with the two Joes—McCarthy and Stalin—that they were to produce only two artists, Saul Bellow and Philip Roth, who left town.”
    —Ishmael Reed (b. 1938)