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:
“When toddlers are unable to speak about urgent matters, they must resort to crying or screaming. This happens even with adults. The voice is the carrier of emotion, and when speech fails us, we need to cry out in whatever form we can to convey our meaning. Often, what passes for negativism is really the toddler’s desperate effort to make herself understood.”
—Alicia F. Lieberman (20th century)
“The principles of the good society call for a concern with an order of being—which cannot be proved existentially to the sense organs—where it matters supremely that the human person is inviolable, that reason shall regulate the will, that truth shall prevail over error.”
—Walter Lippmann (1889–1974)
“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)
“Power, in Case’s world, meant corporate power. The zaibatsus, the multinationals ..., had ... attained a kind of immortality. You couldn’t kill a zaibatsu by assassinating a dozen key executives; there were others waiting to step up the ladder; assume the vacated position, access the vast banks of corporate memory.”
—William Gibson (b. 1948)