Scheduling Using Near-optimal Guard Zones for CDMA Ad Hoc Networks

Abstract

Scheduling algorithms in ad hoc networks allow nodes to share the wireless channel so that concurrent transmissions can be decoded successfully. On one hand, the scheduling needs to be efficient to maximize the spatial reuse and minimize retransmissions due to collisions. But on the other hand, due to the very nature of uncentralized wireless networks, the scheduling algorithm needs to be easily implementable in a distributed fashion with little, if any, coordination with other nodes in the network. The goal of this paper is to propose and evaluate a simple scheduling technique based on receiver guard zones. In particular, using stochastic geometry, we show that a near-optimal guard zone can easily be realized in a distributed manner, and that this has about a 2 - 100x increase in capacity as compared to an ALOHA network; the capacity increase depending primarily on the required outage probability E, as lower E tolerances increasingly reward scheduling. By implementing guard zone-based scheduling, we show that the attained performance is about 70 - 80% of a well-known near-optimal (and practically infeasible) centralized scheme.