Optimal Tradeoff Between Exposed and Hidden Nodes in Large Wireless Networks

TL;DR

This paper analyzes the tradeoff between hidden and exposed nodes in large wireless networks with CSMA, showing that optimal sensing range depends on node activation rate and proposing a threshold-based policy for maximizing throughput.

Contribution

It introduces a threshold policy for sensing range that optimizes throughput based on activation rate, supported by theoretical proofs and simulations.

Findings

Optimal sensing range depends on activation rate.

Existence of a threshold activation rate for optimal sensing.

Threshold policy extends to complex network topologies.

Abstract

Wireless networks equipped with the CSMA protocol are subject to collisions due to interference. For a given interference range we investigate the tradeoff between collisions (hidden nodes) and unused capacity (exposed nodes). We show that the sensing range that maximizes throughput critically depends on the activation rate of nodes. For infinite line networks, we prove the existence of a threshold: When the activation rate is below this threshold the optimal sensing range is small (to maximize spatial reuse). When the activation rate is above the threshold the optimal sensing range is just large enough to preclude all collisions. Simulations suggest that this threshold policy extends to more complex linear and non-linear topologies.