Scheduling and congestion control for fair bandwidth allocation in wireless LANs

High concentration of users in a cell of a wireless LAN leads to an unsustainable traffic load at the access point (AP). An unsuitable solution to the problem will cause poor connectivity for users, severe performance degradation, and possible collapse of the wireless LAN. In this paper, we present a scheduler based on queue length at the AP and a congestion control scheme based on the channel utilization. The traffic flows can be scheduled proportionally to their backlogged queue length while meeting their QoS requirements. The traffic flows that have a higher aggregate rate are more probabilistic to be selected. This policy leads to a fair bandwidth allocation of the total bandwidth. Link utilization is used as a congestion indicator and is informed to the sender to adjust its transmission rate, hence realize congestion control. The link utilization is computed by the channel occupying time in a given time period. The simulation results verify our analysis that our scheduler and congestion control scheme can allocate the bandwidth with considerable fairness.