Neighbor-Medium-Aware MAC Protocol with Fairness for Wireless Ad Hoc Networks

Yongkang XIAO  Lin ZHANG  Xiuming SHAN  Yong REN  Zhengxin MA  

IEICE TRANSACTIONS on Communications   Vol.E87-B   No.9   pp.2738-2746
Publication Date: 2004/09/01
Online ISSN: 
Print ISSN: 0916-8516
Type of Manuscript: PAPER
Category: Wireless Communication Technologies
wireless ad hoc networks,  IEEE 802.11 MAC protocol,  TCP,  neighbor medium aware,  fairness,  

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The unfairness problem among TCP connections has been proved to be very severe in the IEEE 802.11-based wireless ad hoc networks because the hidden station problem still exists and the binary exponential backoff algorithm always favors the latest successful station. In this paper, a novel protocol, neighbor-medium-aware MAC (NEMA-MAC), is proposed to improve the TCP fairness. By adding a medium (channel) state field in the head of the traditional IEEE 802.11 MAC frame, the NEMA-MAC protocol provides a communication mechanism to resolve the hidden station problem. In addition, when a collision occurs, the new backoff algorithm makes the senders cooperatively adjust the contention window according to their local and neighbors' channel usage indexes. The simulation results show that TCP sessions can acquire satisfying fairness and increase the throughput in the NEMA-MAC-based multihop ad hoc networks.