Self-adaptive retransmission for network coding with TCP

Abstract

Incorporating network coding with TCP is a natural way to enhance the robustness and effectiveness of data transmission in lossy channels, it can mask packet loss by mixing data across time and across flows. The key of this approach is a suitable retransmission scheme which can adjust according to the changed of the lossy channel condition. However, most retransmission schemes can't compensate losses effectively. In this paper we propose a novel self-adaptive retransmission scheme combining prospection with compensation, which can dynamically adjust the number and time of coding packets's retransmission according to the channel state change. Compensatory retransmission transmit exact number of packets the receiver needs for decoding all packets based on feedback, and prospective retransmission transmit extra packet before losses happened, and the redundancy factor R is adjusted based on the channel conditions. The scheme can work well on handling not only random losses but also bursty losses. Our scheme also keeps the end-to-end philosophy of TCP that the coding operations are only performed at the end hosts. Thus it is easier to be implemented in practical systems. Simulation results show that our scheme significantly outperforms the previous coding approach in reducing size of decoding matrix and decoding delay, and and produces better TCP-throughput than the standard TCP/NC, TCP-Reno. © 2013 Springer-Verlag.