Robust EKF-Based Wireless Congestion Control

The variation of bandwidth in wireless networks imposes significant challenges to the operation of congestion control protocols, especially, those relying on estimations of link bandwidth. For example, TCP CUBIC probes the end-to-end available link bandwidth while XCP and VCP require an explicit knowledge of the available link bandwidth at intermediate nodes. Thus, these protocols are subject to oscillatory behavior and serious performance deterioration in wireless networks without properly compensating against the fluctuations of the bandwidth. In this paper, we propose a bandwidth estimation scheme utilizing Extended Kalman Filtering (EKF) to which we refer as EBE. Rather than directly measuring bandwidth in real-time, EBE monitors either per flow states at a sender or persistent queue sizes to predict the available bandwidth. It is utilized to efficiently cope with bandwidth variations thereby stabilizing and improving the performance of congestion control protocols in wireless networks. We implement EBE in NS2 and integrate it with XCP, VCP, TCP CUBIC, and few other TCP variants. Through extensive simulation studies, we demonstrate significant performance improvements of these protocols in wireless networks as the result of using EBE.