Achieving packet-level quality of service through scheduling in multirate WLANs

Wireless packet scheduling has been a popular paradigm to achieve packet-level QoS in terms of fairness and throughput in the presence of channel errors. However, the current design does not anticipate the multi-rate capability offered by the IEEE 802.11a/b/g physical layer, thus suffering significant performance degradation in 802.11 WLANs. In this paper, we propose multirate wireless fair scheduling (WMFS). In MWFS, each flow is granted a temporal fair share of the channel, in contrast to the throughput fair share adopted by existing algorithms. Therefore, each flow receives services in proportion to its perceived transmission rate, and high-rate flows are able to opportunistically exploit their good channel conditions and receive more services. MWFS also renovates the compensation model in order to allow for error-prone flows to catch up, thus ensuring fairness for all flows over error-prone channels. We demonstrate the effectiveness of MWFS through both simulations and analysis. Especially, WMFS achieves system throughput 159% of state-of-the-art scheduling algorithms in simulated scenarios.