Spatial CSMA: A Distributed Scheduling Algorithm for the SIR Model with Time-varying Channels

TL;DR

This paper introduces a distributed CSMA algorithm that operates under a realistic SIR interference model with time-varying channels, proving throughput optimality and demonstrating improved performance over traditional conflict graph-based methods.

Contribution

It presents a novel adaptive CSMA algorithm for the SIR model with dynamic channels, extending prior work beyond static, conflict graph assumptions.

Findings

Algorithm achieves throughput optimality under the SIR model.

Parallel update technique improves convergence rate.

Outperforms conflict graph-based algorithms in throughput and speed.

Abstract

Recent work has shown that adaptive CSMA algorithms can achieve throughput optimality. However, these adaptive CSMA algorithms assume a rather simplistic model for the wireless medium. Specifically, the interference is typically modelled by a conflict graph, and the channels are assumed to be static. In this work, we propose a distributed and adaptive CSMA algorithm under a more realistic signal-to-interference ratio (SIR) based interference model, with time-varying channels. We prove that our algorithm is throughput optimal under this generalized model. Further, we augment our proposed algorithm by using a parallel update technique. Numerical results show that our algorithm outperforms the conflict graph based algorithms, in terms of supportable throughput and the rate of convergence to steady-state.