On improving the TCP performance in asymmetric wireless mesh networks

Abstract

A wireless network with multi-hop wireless links is called a wireless mesh network (WMN). WMNs have so many advantages over conventional wireless networks and can be used for various applications. Specifically, WMNs can provide quick and cost-effective Internet connectivity where conventional wired networks impossible to be rolled out. The major disadvantage WMNs however stems from the fact that wireless links' rate is highly affected by physical and environmental conditions which can lead to unpredictable data transmission errors. Changes in environmental conditions also result in asymmetric links characteristics within the network in terms of latency, transmission rates, and data path. In this paper, we conduct simulation study to examine the impact of network path asymmetry on TCP performance over wireless mesh networks. The simulation results we have obtained confirm that network path asymmetry severely degrades TCP performance. We then propose a new TCP enhancement mechanism called TCP-WAM (TCP for wireless asymmetric networks) whose transfer rate during losses is less dependent on ACKs. Finally we evaluate TCP-WAM performance by conducting several simulation experiments and our results indicate that TCP-WAM performs well especially in highly asymmetric environments.