图14.3IEEE802.11标准中的MAC层 LLC 1EEE802.1 sublayer Contention-free Data link service Contention layer service Point coordination function(PCF) MAC sublayer Distributed coordination function(DCF) Physical 802.11 802.11 802.11 802.11a 802.11a 802.11g layer FHSS DSSS Infrared DSSS OFDM DSSS 14.714.7 图14.3 IEEE 802.11标准中的MAC层