Research And Improvement Of MAC Protocol In Wireless Local Area Networks

Wireless Local Area Network (WLAN) is one kind of wireless networks which combinates between computer network and wireless communication technique. As the extendibility of wired network, WLAN has been widely used in every way of life because it has good features such as the application of flexible, fast installation, shot construction period and good applicability.In WLAN, the performance of network depends primarily on access to the MAC sublayer protocol, so design of MAC protocol is a key problem. Research about MAC protocol in WLAN and improvement of network throughput, fairness and low delay are the critical factors in academic and professional fields now.MAC channel contention algorithm is very important for reducing the collision probability and improving the throughput of the network. Firstly, this paper gets the distribution of frame size by caputuring the frame on the wireless channel. Nextly, this paper analyzes the impact of different frame size and multirate on the network throughput, and designs an algorithm whose name is FRA(Frame-cum-Rate Algorithm). In FRA, the value of CW_min is adjusted based on frame size and transmission rate. The wireless station with large frame size and high transmission rate can obtain high probability to access wireless channel. Simulation results show that compared with DCF, FRA increases the network throughput drasmaticaly when different frame size and transmission rate coexist.Subsequently, this paper analyzes MAC medium access delay and throughput based on Markov model with certain BER on the wireless channel. It gives a more precise computing model comparision with previous research.The dissertation summarizes our research work in the last chapter and a further research direction has been explored for future work.