The Impact of Capture on Multihop Wireless Networks in an Optimal Rate Control Framework

We consider the end-to-end fair rate control problem in a multi-hop Aloha network with capture. Capture (also referred to as co-channel interference tolerance) occurs when a packet with a stronger signal strength can be correctly decoded at the receiver despite the presence of a weaker interfering signal. We provide an approximate model for the link capacity with capture and incorporate it into a cross-layer joint link/session rate optimization framework. We show that this is a convex optimization problem and then present a sub-gradient algorithm for realistic distributed implementation in a network. Through analysis and simulations, we quantify the improvement in performance obtained with capture. We find that the capture effect benefits primarily low-contention links and non-bottle-neck sessions. As a result, although capture provides significant improvements in the total throughput (sum rate), it seems to provide little improvement in the objective function (sum of the logarithm of the rates).