Sequential Coordination Function for Throughput and Fairness Enhancement of Wireless LANs

High throughput and fair resource sharing are two of the most important objectives in designing a medium access control (MAC) protocol. Currently, most MAC protocols including IEEE 802.11 DCF adopt a random access based approach in a distributed manner in order to coordinate the wireless channel accesses among competing stations. In this paper, we first identify that a random access–based MAC protocol may suffer from MAC protocol overhead such as a random backoff for data transmission and a collision among simultaneously transmitting stations. Then, we propose a new MAC protocol, called sequential coordination function (SCF), which coordinates every station to send a data frame sequentially one after another in a distributed manner. By defining a service period and a joining period, the SCF eliminates unnecessary contentions during the service period, and by explicitly determining the sequence of frame transmission for each stations, it reduces collision occurrences and ensures fairness among stations in the service period. The performance of SCF is investigated through intensive simulations, which show that the SCF achieves higher throughput and fairness performances than other existing MAC protocols in a wide range of the traffic load and the number of stations. Index Terms Wireless LAN, medium access control, throughput, and fairness A preliminary version of this paper has been presented at the IEEE Global Communications Conference, Nov. 29 – Dec. 3, 2004 [1]. C. Lim is with the Telecommunication R&D Center, Samsung Electronics Co., LTD., Suwon, Korea. C.-H. Choi is with the School of Electrical Engineering and Computer Science, Seoul National University, Seoul, Korea. H. Lim is with the Department of Information and Communications, Gwangju Institute of Science and Technology, Gwangju, Korea. Email: [email protected] April 30, 2011 DRAFT