Rigorous and Practical Proportional-fair Allocation for Multi-rate Wi-Fi

TL;DR

This paper introduces a rigorous analytical model for multi-rate Wi-Fi networks and proposes a proportional-fair allocation scheme that significantly improves network utility, throughput, and download times in real-world deployments.

Contribution

It presents the first accurate, tractable model for 802.11 multi-rate throughput and airtime, and develops a practical proportional-fair allocation solution with proven performance benefits.

Findings

Up to 100% utility gains in network performance

Doubling of video streaming goodput

8x reduction in TCP download times

Abstract

Recent experimental studies confirm the prevalence of the widely known performance anomaly problem in current Wi-Fi networks, and report on the severe network utility degradation caused by this phenomenon. Although a large body of work addressed this issue, we attribute the refusal of prior solutions to their poor implementation feasibility with off-the-shelf hardware and their imprecise modelling of the 802.11 protocol. Their applicability is further challenged today by very high throughput enhancements (802.11n/ac) whereby link speeds can vary by two orders of magnitude. Unlike earlier approaches, in this paper we introduce the first rigorous analytical model of 802.11 stations' throughput and airtime in multi-rate settings, without sacrificing accuracy for tractability. We use the proportional-fair allocation criterion to formulate network utility maximisation as a convex optimisation problem for which we give a closed-form solution. We present a fully functional light-weight implementation of our scheme on commodity access points and evaluate this extensively via experiments in a real deployment, over a broad range of network conditions. Results demonstrate that our proposal achieves up to 100\% utility gains, can double video streaming goodput and reduces TCP download times by 8x.