Measurement and Modeling of the Origins of Starvation of Congestion-Controlled Flows in Wireless Mesh Networks

• Published in: IEEE/ACM transactions on networking Vol. 17; no. 6; pp. 1832 - 1845
• Main Authors: Gurewitz, O., Mancuso, V., Jingpu Shi, Knightly, E.W.
• Format: Journal Article
• Language: English
• Published: New York IEEE 01.12.2009; The Institute of Electrical and Electronics Engineers, Inc. (IEEE)
• Subjects: Analytical models; Bandwidth; Experimental; fairness; Fluid flow measurement; IEEE 802.11; mesh; Mesh networks; Spread spectrum communication; Studies; TCP; Telecommunication traffic; Testing; Throughput; Traffic control; Wireless mesh networks; Wireless networks
• ISSN: 1063-6692; 1558-2566
• DOI: 10.1109/TNET.2009.2019643

Significant progress has been made in understanding the behavior of TCP and congestion-controlled traffic over CSMA-based multihop wireless networks. Despite these advances, however, no prior work identified severe throughput imbalances in the basic scenario of mesh networks, in which a one-hop flow contends with a two-hop flow for gateway access. In this paper, we demonstrate via real network measurements, testbed experiments, and an analytical model that starvation exists in such a scenario; i.e., the one-hop flow receives most of the bandwidth, while the two-hop flow starves. Our analytical model yields a solution consisting of a simple contention window policy that can be implemented via standard mechanisms defined in IEEE 802.11e. Despite its simplicity, we demonstrate through analysis, experiments, and simulations that the policy has a powerful effect on network-wide behavior, shifting the network's queuing points, mitigating problematic MAC and transport behavior, and ensuring that TCP flows obtain a fair share of the gateway bandwidth, irrespective of their spatial location.