On the Importance of Loss Differentiation for Link Adaptation in Wireless LANs

In current wireless LANs multiple kinds of losses occur (i.e., channel errors, collisions, interference). In this paper we examine the extent to which loss differentiation based physical layer transmission bit–rate and contention window adaptation aids in improving network performance. We show that loss differentiation can have a positive impact on performance, especially in low contention scenarios. Crucially, the same performance can also be achieved even without the use of loss differentiation as long as the appropriate rate and contention window adaptation mechanisms are used. Our study on the impact of loss differentiation led us to develop Themis, a novel bit–rate and contention window adaptation scheme that does not rely on loss differentiation. Themis considerably improves performance over both the standard 802.11a/b/g and SampleRate in terms of throughput and fairness by reducing hidden nodes.