Multiple Access with Collision Avoidance (MACA) is a slotted
media access control
In IEEE 802 LAN/MAN standards, the medium access control (MAC, also called media access control) sublayer is the layer that controls the hardware responsible for interaction with the wired, optical or wireless transmission medium. The MAC sublay ...
protocol used in wireless LAN data transmission to avoid collisions caused by the
hidden station problem and to simplify
exposed station problem.
The basic idea of MACA is a wireless network node makes an announcement before it sends the data frame to inform other nodes to keep silent. When a node wants to transmit, it sends a signal called ''Request-To-Send'' (RTS) with the length of the data frame to send. If the receiver allows the transmission, it replies the sender a signal called ''Clear-To-Send'' (CTS) with the length of the frame that is about to receive.
Meanwhile, a node that hears RTS should remain silent to avoid conflict with CTS; a node that hears CTS should keep silent until the data transmission is complete.
WLAN data transmission collisions may still occur, and the MACA for Wireless (
MACAW) is introduced to extend the function of MACA. It requires nodes sending acknowledgements after each successful frame transmission, as well as the additional function of Carrier sense.
External links
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Phil Karn
Phil Karn (born October 4, 1956) is a retired American engineer from Lutherville, Maryland. He earned a bachelor's degree in electrical engineering from Cornell University in 1978 and a master's degree in electrical engineering from Carnegie Mel ...
MACA - A New Channel Access Method for Packet Radio (Phil Karn, KA9Q)
{{DEFAULTSORT:Multiple Access With Collision Avoidance
Media access control
de:Carrier Sense Multiple Access/Collision Avoidance#RTS/CTS Koordination