Distinguishing between channel errors and collisions in IEEE 802.11

An important factor compromising the efficiency of IEEE 802.11 based networks and the rate adaptation algorithms they use is their inability to distinguish between packet losses caused by collisions and packet losses caused by channel errors. In this paper, we present a mechanism based on Error Vector Magnitude (EVM) to discern random channel errors from collisions in wireless networks. We show that EVM can be used not only for collision detection but it can also be used to locate the portion of a packet affected by a collision. The proposed methodology uses a classification and regression trees based procedure to develop a thresholding mechanism for EVM to distinguish between the two types of packet corruptions.