The Impact of Interference Cancellation on the Uplink Throughput of WLAN with CSMA/CA

The potential of multi-antenna interference cancellation receiver algorithms for increasing the uplink throughput in WLAN systems such as 802.11x is investigated. The medium access control in such systems is based on carrier sensing multiple-access with collision avoidance (CSMA/CA), which itself is a powerful tool for the mitigation of intra-system interference. However, due to the spatial dependence of radio signal strengths, it is possible for the collision avoidance mechanism to fail resulting in packet collisions at the receiver and a reduction in system throughput. The CSMA/CA MAC protocol can be complemented in such scenarios by interference cancellation algorithms at the PHY layer. The corresponding gains in throughput are a result of the complex interplay between the PHY and MAC layers, and are evaluated in this paper via cross-layer simulations. It is shown that the uplink throughput can potentially be substantially increased with the use of two-antenna interference cancellation at the access point.