Exploiting physical layer detection techniques to mitigate starvation in CSMA/CA wireless networks

Abstract

Many proposed and implemented wireless MAC protocols are based on collision-avoidance handshakes between senders and receivers. Unfortunately, information asymmetry problems can potentially occur with such protocols and severely reduce the network capacity. In this paper, we introduce a receiver-initiated mechanism, called carrier sense multiple access with collision avoidance by receiver detection (CSMA/CARD), that makes use of collisions sensed at the physical layer of a receiver to mitigate the effect of such problems. More specifically, and depending on the exact nature of the handshake mechanism, collisions can be used by the receiver to predict whether some sender attempted to initiate a transmission towards this receiver. The receiver, in its turn, would initiate an action on its own to help expedite the handshake mechanism. Such a simple cooperation mechanism can be coupled with any appropriate MAC protocol to improve its performance. We evaluate the effectiveness of this approach with the 802.11 DCF MAC in particular, and we show that starvation and unfairness results can be highly mitigated