End-to-end performance and fairness in multihop wireless backhaul networks

TLDR

Wireless IEEE 802.11 networks in homes, small businesses, and public hotspots often face the wired access link as the slowest and most expensive part of the end‑to‑end path, prompting proposals for multi‑hop wireless backhaul, yet existing media access and transport protocols can cause severe unfairness and starvation for flows farther from the wired entry point. The study aims to evaluate fairness and end‑to‑end performance in multihop wireless backhaul networks. The authors develop a formal reference model to remove spatial bias and maximize spatial reuse, run extensive simulations to assess the impact of MAC protocols, congestion control, antenna technology, and traffic types, design a distributed layer‑2 fairness algorithm that operates without modifying TCP, and analyze the trade‑off between fairness and aggregate throughput to determine the fairness‑constrained capacity of multihop wireless backhaul networks.

Abstract

Wireless IEEE 802.11 networks in residences, small businesses, and public "hot spots" typically encounter the wireline access link (DSL, cable modem, T1, etc.) as the slowest and most expensive part of the end-to-end path. Consequently, network architectures have been proposed that employ multiple wireless hops in route to and from the wired Internet. Unfortunately, use of current media access and transport protocols for such systems can result in severe unfairness and even starvation for flows that are an increasing number of hops away from a wired Internet entry point. Our objective is to study fairness and end-to-end performance in multihop wireless backhaul networks via the following methodology. First, we develop a formal reference model that characterizes objectives such as removing spatial bias (i.e., providing performance that is independent of the number of wireless hops to a wire) and maximizing spatial reuse. Second, we perform an extensive set of simulation experiments to quantify the impact of the key performance factors towards achieving these goals. For example, we study the roles of the MAC protocol, end-to-end congestion control, antenna technology, and traffic types. Next, we develop and study a distributed layer 2 fairness algorithm which targets to achieve the fairness of the reference model without modification to TCP. Finally, we study the critical relationship between fairness and aggregate throughput and in particular study the fairness-constrained system capacity of multihop wireless backhaul networks.