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Online Loss Differentiation Algorithm with One-Way Delay for TCP Performance Enhancement


Minsu Shin, Mankyu Park, Byungchul Kim, Jaeyong Lee, Deockgil Oh


Vol. 11  No. 4  pp. 26-36


In this paper for the performance enhancement of TCP protocol in the mixed wired/wireless network, packet loss differentiation algorithm is proposed which distinguishes the nature of losses and decides congestion control action accordingly. TCP protocol takes packet loss as an indication of network congestion so that it reduces its congestion window into half. However, packet loss can be more likely induced by wireless bit error in the wireless network and the performance of TCP in such a network could be unnecessarily degraded by the lack of the ability to identify the cause of the losses. To reduce the effect of the problem, we propose the accurate online loss differentiation algorithm making use of the one-way delay on the forward path. Our contributions are in twofold. First, we introduce the detection and removal of the clock offset existing between sender and receiver clocks only with the information available at the sender side which make our algorithm easy to deploy, and therefore calculate accurate one-way delay on the forward path. Second, we consider the possibility that wireless loss would occur even in the situation of network congestion, and to the best of our knowledge it is the only algorithm that takes this probability into account. We propose two-phase loss differentiation algorithm that uses the ratio of the average one-way delay in the lossless period and lossy period to decide the existence of congestion in the first phase, and the statistical property of the one-way delay for the congestion loss in the second phase. From the simulation results, we showed that our algorithm can provide better accuracy both for the congestion and wireless losses


TCP, loss differentiation, one-way delay, clock synchronization, congestion loss