A Fast-CSMA Algorithm for Deadline-Constrained Scheduling over Wireless Fading Channels

TL;DR

This paper introduces a Fast-CSMA algorithm designed for deadline-constrained scheduling over wireless fading channels, addressing delays and convergence issues in real-time traffic management.

Contribution

The paper proposes a novel Fast-CSMA policy that is proven to be optimal for serving real-time traffic with deadlines over fading channels in fully-connected networks.

Findings

Fast-CSMA supports all traffic within the maximal satisfiable set.

The proposed algorithm outperforms existing CSMA-based methods in simulations.

Theoretical analysis confirms the optimality of Fast-CSMA for deadline-constrained scheduling.

Abstract

Recently, low-complexity and distributed Carrier Sense Multiple Access (CSMA)-based scheduling algorithms have attracted extensive interest due to their throughput-optimal characteristics in general network topologies. However, these algorithms are not well-suited for serving real-time traffic under time-varying channel conditions for two reasons: (1) the mixing time of the underlying CSMA Markov Chain grows with the size of the network, which, for large networks, generates unacceptable delay for deadline-constrained traffic; (2) since the dynamic CSMA parameters are influenced by the arrival and channel state processes, the underlying CSMA Markov Chain may not converge to a steady-state under strict deadline constraints and fading channel conditions. In this paper, we attack the problem of distributed scheduling for serving real-time traffic over time-varying channels. Specifically, we consider fully-connected topologies with independently fading channels (which can model cellular networks) in which flows with short-term deadline constraints and long-term drop rate requirements are served. To that end, we first characterize the maximal set of satisfiable arrival processes for this system and, then, propose a Fast-CSMA (FCSMA) policy that is shown to be optimal in supporting any real-time traffic that is within the maximal satisfiable set. These theoretical results are further validated through simulations to demonstrate the relative efficiency of the FCSMA policy compared to some of the existing CSMA-based algorithms.