Issue No.11 - November (2007 vol.6)
The contention resolution scheme is a key component in carrier sense based wireless MAC protocols. It has a major impact on MAC’s performance metrics such as throughput, delay, and jitter. The IEEE 802.11 DCF adopts a simple contention resolution scheme, namely Binary Exponential Backoff (BEB) scheme. The BEB achieves a reasonable performance for transmitting best-effort packets in small-size wireless networks. However, as the network size increases, it suffers from inefficiency because of the medium contention, which leads to reduced performance. The main reason is that the BEB mechanism incurs an everincreasing collision rate as the number of contending nodes increases. We devise a novel contention resolution scheme, a k-round elimination contention (k-EC) scheme. The k-EC scheme exhibits high efficiency and robustness during the collision resolution. More importantly, it is insensitive to the number of contending nodes. This feature makes it feasible for use in networks of different sizes. Simulation results show that the k-EC scheme offers a powerful remedy to medium contention resolution. It significantly outperforms the IEEE 802.11 DCF scheme in all the MAC’s performance metrics, and also exhibits better fairness.
Wireless communication, Network Protocols, Access schemes
Bosheng Zhou, Alan Marshall, Tsung-Han Lee, "A k-Round Elimination Contention Scheme for WLANs", IEEE Transactions on Mobile Computing, vol.6, no. 11, pp. 1230-1244, November 2007, doi:10.1109/TMC.2007.70715