Improving flow level fairness and interactivity in WLANs using size-based scheduling policies

In this paper, we investigate the use of a size-based schedul- ing policy, LASTOTAL, inWLANs. A size-based scheduling policy is a priority policy where the priority of a flow is based on its size. LASTOTAL replaces the legacy IP level FIFO scheduler at the access point. The lower protocol layers, and especially the MAC 802.11 layer are left unchanged. We demonstrate using realistic synthetic workloads, that LAS- TOTAL solves the unfairness issue due to DCF in 802.11 WLANs and ensures small response times to the majority of the flows under any load conditions. The latter property is desirable as short flows correspond to interactive appli- cations and maintaining low response times for those flows despite load variations, significantly improves user experi- ence. We also introduce and validate Markovian queuing models to assess the response time of the access point for both FIFO and LASTOTAL.