Parallel contention algorithm with CSMA/CA for OFDM based high speed wireless LANs

The data rates of wireless networks are getting faster and faster. With this trend, IEEE 802.11a, published in 1999 to provide faster data transmission rates, is one of the strongly considered next generation wireless LAN standards. It uses CSMA/CA as the medium access control protocol and OFDM as the physical layer technology. In this paper, to enhance the throughput performance of CSMA/CA protocol in the OFDM based wireless LAN like IEEE 802.11a, we propose a new contention algorithm called parallel contention algorithm that divides the subcarriers into multiple groups to reduce the contention time. We analyze our proposed scheme by extending the Markov chain model and verify the accuracy of the analysis through the simulations. Our protocol performs well especially when the transmission speed and the number of users are getting higher, thereby achieving a better performance improvement ratio than the original IEEE 802.11a standard. Keywords-802.11; wireless LAN; CSMA/CA; contention window