An effective way to improve TCP performance in wireless/mobile networks

TCP congestion control has been developed on the assumption that congestion in the network to be the only cause for packet loss. Thus, it drops its transmit window upon detecting a packet loss. In the presence of high error rates and intermittent connective characteristic of the wireless link, these results in an unnecessary reduction in link bandwidth utilization for packet losses are not mainly due to congestion. This paper provides an effective way to improve TCP performance in wireless and mobile networks. As routers will still have to rely on packet drops as indications of congestion, we propose to add wireless-ECN just upon the first packet loss that occurs. In this way, it strongly achieves separation of the congestion control and loss recovery mechanism by quickly informing the sender that a loss happened because of reasons related to network congestion. The unnecessary window reduction caused by lost packets due to link errors is avoided. Compared to the current ECN proposal used in traditional wired networks with the purpose of avoiding unnecessary packet losses, it is simple to implement for the complexity and inconsistency of buffer management in the networks and more conservative TCP congestion control over a short-scale period which is required in the ECN scheme is avoided. Since packet losses due to buffer overflow are not allowed to invoke congestion control if applied in an ECN wireless environment, when encountering congestion losses in such a case the addition of wireless-ECN can represent these packet losses to initiate window reduction in time and improve the ECN performance across imperfect links.