QoS based aggregation in high speed IEEE802.11 wireless networks

We propose a novel frame aggregation algorithm with statistical delay guarantee for high speed IEEE802.11 networks considering link quality fluctuations. We use the concept of effective capacity to formulate frame aggregation with QoS guarantee as an optimization problem. The QoS guarantee is in the form of a target delay bound and violation probability. We apply proper approximations to derive a simple formulation, which is solved using a Proportional-Integral-Derivative (PID) controller. The proposed PID aggregation algorithm independently adapts the amount of time allowance for each link, while it needs to be implemented only at the Access Point (AP), without requiring any change to the 802.11 Medium Access Control (MAC). More importantly, the aggregator does not consider any physical layer or channel information, as it only makes use of queue level metrics, such as average queue length and link utilization, for tuning the amount of time allowance. NS-3 simulations show that our proposed scheme outperforms Earliest Deadline First (EDF) scheduling with maximum aggregation size and pure deadlinebased aggregation, both in terms of maximum number of stations and channel efficiency.