Abstract

works (WMNs) can be used to provide last mile Inter-net access. These networks exhibit extreme unfairness with backlogged traffic sources. Current solutions pro-pose distributed source rate control algorithms requir-ing MAC or transport-layer changes on all mesh nodes. This is often infeasible in large practical deployments. In wireline networks, router-assisted rate control tech-niques have been proposed for use alongside end-to-end mechanisms. We wish to evaluate the feasibility of es-tablishing similar centralized control via gateways in WMNs. In this paper we focus on the efficacy of this control, rather than the specifics of the controller design mechanism. We answer the question: Given sources that react predictably to congestion notification, can we en-force a desired rate allocation through a single central-ized controller? The answer is not obvious because flows experience varying contention levels, and transmissions are scheduled by CSMA/CAMAC using imperfect local knowledge. We find that common router-assisted flow control schemes used in wired networks fail in WMNs because they assume: (1) links are independent, and (2) router queue buildups are sufficient for detecting con-gestion. We show that non-work-conserving rate-based centralized scheduling can effectively enforce rate allo-cation. It can achieve results comparable to source rate limiting, without requiring any modifications to mesh routers or client devices.