Q12Mobile Computing
Question
Describe the MAC protocol IEEE 802.11 with its frame format.
Answer
IEEE 802.11 uses CSMA/CA for MAC, which avoids collisions using RTS/CTS. Its frame format includes frame control, duration, four addresses, sequence control, frame body, and FCS.
IEEE 802.11 defines the MAC layer for wireless LANs. Because wireless radios cannot easily detect collisions (CSMA/CD doesn't work), it uses Carrier Sense Multiple Access with Collision Avoidance (CSMA/CA). It utilizes an optional Request to Send (RTS) and Clear to Send (CTS) mechanism to handle the hidden terminal problem. The general 802.11 MAC frame format consists of a MAC header (including Frame Control, Duration/ID, Address 1, Address 2, Address 3, Sequence Control, and Address 4), a variable-length Frame Body (containing the payload), and a Frame Check Sequence (FCS) for error detection.