Thomas Kunz
Systems and Computer Engineering
168
802.11 MAC Layer
nTraffic services
–Asynchronous
Data Service (mandatory)
nexchange of data packets based on “best-effort”
nsupport of broadcast and multicast
–Time-Bounded
Service (optional)
nimplemented using PCF (Point Coordination Function)
nAccess methods
–DCF CSMA/CA
(mandatory)
ncollision avoidance via randomized „back-off“
mechanism
nminimum distance between consecutive packets
nACK packet for acknowledgements (not for
broadcasts)
–DCF w/
RTS/CTS (optional)
nDistributed Foundation Wireless MAC (DFWMAC)
navoids hidden terminal problem
–PCF
(optional)
naccess point polls terminals according to a list