Abstract: IEEE 802.11a is a popular high-speed WLAN standard with a data rate up to 54 Mps.The basic Medium Access Control (MAC) protocol of IEEE 802.11a is the contention-based distributed coordination function.DCF includes two access mechanisms:basic access mechanism and RTS/CTS access mechanism.In this paper, an analysis and comparison of saturation throughput and access delay of these two access mechanisms in IEEE 802.11a WLAN is conducted by introducing a two-dimensional Markov model.The study reveals that, in contradiction to the situation in IEEE 802.11 WLAN, basic access mechanism is always more effective than RTS/CTS mechanism in high-speed IEEE 802.11a WLAN.

Key words: IEEE802.11a, saturation throughput, access delay, DCF