An Experimental Comparison of Layer 2 and 3 Mechanisms for Improving User Perceived Performance of 802.11 Wireless LANs

We propose LAS-ACK (Least Attained Service with TCP ACKs), a new layer 3 scheduling mechanism for solving the TCP unfairness problem in 802.11 wireless LANs. We evaluate its performance through measurements of a realistic TCP workload on a wireless platform, using a variety to metrics that reflect the user perceived performance as well as the efficiency at the network layer. The proposed mechanism achieves even better results if combined with AAP (Asymmetric Access Point), a MAC layer access method that gives more capacity to the access point. We show that an efficient way to combine AAP and LAS-ACK is to deploy LAS-ACK at the wireless stations only. This is a desirable property as it allows to keep the access point fairly simple and shifts the computational complexity of LAS-ACK to the wireless stations that have much more resources than the access point in general.