Evaluation and Enhancement of TCP with Network Coding in Wireless Multihop Networks

In this paper, we, based on NS-2 simulator, evaluate the performances of different TCP protocols with network coding in wireless multihop networks, and then propose two schemes to enhance the performances of TCPs with network coding. In particular the network coding scheme considered and used here is COPE, which is one of the well-known practical network coding schemes, the TCP protocols evaluated are TCP-NewReno, TCP-FeW and TCP-AP, and the TCP protocols with COPE are implemented in NS-2. The simulation results show that COPE performs very differently in improving the performances of the TCP’s in different wireless network topologies. In some topologies COPE performs well, resulting in significant performance improvement; while in other ones it performs worse than the same cases without network coding. To overcome this problem, we propose two schemes to improve the performance of TCP with network coding. One is called Encode Once, which ensures the packet being encoded at most one time. The other is called Network Coding Aware TCP, in which the transmitting rate of TCP is made adaptive to the status of the node’s output queue. The evaluation results indicate that the proposed two schemes can significantly improve the goodputs of TCP’s with network coding, and the latter scheme performs better.