Proportional Fair Coding for Wireless Mesh Networks

TL;DR

This paper develops a novel approach for joint airtime and coding rate allocation in multi-hop wireless networks, achieving proportional fairness while considering delay deadlines and channel losses.

Contribution

It introduces a method to decompose a non-convex utility optimization into convex problems, providing explicit solutions for fair airtime and coding rate allocation.

Findings

Derived explicit solutions for joint airtime and coding rate allocation.

Proved the decomposition of a non-convex problem into convex subproblems.

First analysis of utility fair joint allocation with delay deadlines in wireless networks.

Abstract

We consider multi--hop wireless networks carrying unicast flows for multiple users. Each flow has a specified delay deadline, and the lossy wireless links are modelled as binary symmetric channels (BSCs). Since transmission time, also called airtime, on the links is shared amongst flows, increasing the airtime for one flow comes at the cost of reducing the airtime available to other flows sharing the same link. We derive the joint allocation of flow airtimes and coding rates that achieves the proportionally fair throughput allocation. This utility optimisation problem is non--convex, and one of the technical contributions of this paper is to show that the proportional fair utility optimisation can nevertheless be decomposed into a sequence of convex optimisation problems. The solution to this sequence of convex problems is the unique solution to the original non--convex optimisation. Surprisingly, this solution can be written in an explicit form that yields considerable insight into the nature of the proportional fair joint airtime/coding rate allocation. To our knowledge, this is the first time that the utility fair joint allocation of airtime/coding rate has been analysed, and also, one of the first times that utility fairness with delay deadlines has been considered.