Optimal distributed scheduling for single-hop wireless networks

Abstract

We consider the problem of optimal distributed scheduling for delay minimization in single-hop wireless networks. We focus on static scheduling policies, where the CSMA channel access rates are determined by the long-run traffic statistics, but not the instantaneous queue states. Such static scheduling is preferable over dynamic scheduling policies like max-weight when the traffic flows are heterogeneous. In this paper, we formulate the problem of optimizing the channel access rates of different links subject to an upper bound on the access rate of each link. This is a hard non-convex optimization. We propose an approximate solution that is asymptotically optimal in the limit as the maximum permissible channel access rate grows to infinity. We also study the role of the intra-queue scheduling policy. Specifically, we consider two policies: first come first served (FCFS) and pre-emptive last come first served (PLCFS). Analogous to the case of an M/G/1 queue, we show that PLCFS is preferable to FCFS for highly variable flows.