论文信息 - A Novel Collision Avoidance Algorithm for IEEE 802.11 Wireless LANs

A Novel Collision Avoidance Algorithm for IEEE 802.11 Wireless LANs

As the contention resolution scheme in IEEE 802.11, binary exponential back off (BEB) has long been criticized for its high collision probability in saturation situation. In this paper, a novel contention resolution algorithm is designed to overcome its disadvantage. The cause of BEB's poor performance is identified as the overlapped back off intervals of stations and the restoration of contention window to the smallest value upon a successful transmission. Therefore two new concepts, namely back off interval isolation (BII) and improved slow decrease (ISD), are proposed in our enhanced collision avoidance (ECA) algorithm. BII introduces an extra back off interval selection process and stations at different stages have separated back off intervals. With ISD, contention window can only decrease after a certain number of successive successful transmissions. Two dimensional Markov chain is utilized to model the contention resolution process and the theoretical performance of ECA is also deduced. Simulation results show that our algorithm outperforms BEB in both throughput and delay by lowering the collision probability.

[1] Nah-Oak Song,et al. Enhancement of IEEE 802.11 distributed coordination function with exponential increase exponential decrease backoff algorithm , 2003, The 57th IEEE Semiannual Vehicular Technology Conference, 2003. VTC 2003-Spring..

[2] Der-Jiunn Deng,et al. Contention window optimization for ieee 802.11 DCF access control , 2008, IEEE Transactions on Wireless Communications.

[3] Thierry Turletti,et al. Enhancing IEEE 802.11 MAC in congested environments , 2004 .

[4] Der-Jiunn Deng,et al. Slow Start Backoff Algorithm for Ad-Hoc Wireless Networks , 2010, 2010 IEEE Global Telecommunications Conference GLOBECOM 2010.

[5] A. Girotra,et al. Performance Analysis of the IEEE 802 . 11 Distributed Coordination Function , 2005 .

[6] V. Bharghavan,et al. MACAW: A media access protocol for wireless LANs , 1994 .

[7] Zhang Han,et al. Adaptive Access Mechanism with Optimal Contention Window Based on Node Number Estimation Using Multiple Thresholds , 2012, IEEE Transactions on Wireless Communications.

[8] Yoon Hyuk Kim,et al. Channel Condition Based Contention Window Adaptation in IEEE 802.11 WLANs , 2012, IEEE Transactions on Communications.

[9] Qin Yu,et al. Dynamic contention window adjustment scheme for improving throughput and fairness in IEEE 802.11 wireless LANs , 2012, 2012 IEEE Global Communications Conference (GLOBECOM).