New loss recovery strategy for wireless TCP

Abstract

As the underlying network technologies and popular applications have been evolved, Transmission Control Protocol (TCP) shows unexpected and degraded performance because TCP cannot adapt itself to the new environment. This network environment change forces TCP to evolve. For example, new networks such as wireless networks makes TCP modify congestion control to accommodate the different characteristic of wireless networks. For another instance, a few applications requiring real time and reliable control such as networking game and remote desktop require TCP to faster respond. Even though many researchers already pay attention to this problem. their proposals are limited only on modifying congestion control and their proposals shows undesirable results under the high packet loss rate environment. Moreover, even though accompanying the ideal congestion control, TCP does not achieve the good performance with random packet loss. In this dissertation, we point out the enhanced congestion controls for wireless TCP are not enough. Under high packet loss rate, the enhanced congestions control for wireless TCP become unstable and do not work well as proposed. We shows this phenomenon comes from TCP``s complex dynamics during loss recovery. In details, the loss recovery ability of TCP varies with packet loss rate and TCP finally fails to detect multiple packet losses. Only RTO expiry can break this failure and start sending packets again. We found the packet transmission order is helpful to detect multiple packet losses, which can alleviate this limitation. Under high packet loss rate, TCP should frequently retransmit lost packets. The order of packet transmission is eventually not matched with the order of packet``s sequence number. At the same time, the packet transmission order becomes very important in that a packet is assumed to be lost if later-sent packets arrive before this packet. Therefore, TCP can detect lost packets only if TCP remembers the packet transmissi...