The Effect of Scheduling on Link Capacity in Multi-hopWireless Networks

Abstract

Existing models of Multi-Hop Wireless Networks (MHWNs) assume that interference estimators of link quality such as observed busy time predict the capacity of the links. We show that these estimators do not capture the intricate interactions that occur at the scheduling level, which have a large impact on effective link capacity under contention based MAC protocols. We observe that scheduling problems arise only among those interfering sources whose concurrent transmissions cannot be prevented by the MAC protocol's collision management mechanisms; other interfering sources can arbitrate the medium and coexist successfully. Based on this observation, we propose a methodology for rating links and show that it achieves high correlation with observed behavior in simulation. We then use this rating as part of a branch-and-bound framework based on a linear programming formulation for traffic engineering in static MHWNs and show that it achieves considerable improvement in performance relative to interference based models.