TCP with hop-oriented network coding in multi-radio multi-channel wireless mesh networks

In multi-radio multi-channel wireless mesh networks (MRMC WMNs), the performance of transmission control protocol (TCP) significantly deteriorates when non-congestion packet losses occur. TCP-hop-oriented network Coding (HONC) is proposed in this study to improve the performance of TCP with hop-oriented network coding in MRMC WMNs. It combines a block of inter- and intra-flow packets that share a same next-hop node by random linear network coding, and then it forwards and acknowledges these blocks hop by hop. Distributed rate control and path selection algorithm is introduced to effectively utilise network resources and balance load from congested paths to non-congested ones. The simulations show that TCP-HONC achieves a significant throughput gain. Meanwhile, the end-to-end delay and delay jitter of TCP-HONC are relatively small even with a high loss rate. TCP-HONC outperforms TCP/NC_end-to-end by 236% and TCP/NC_hop-by-hop by 143% in throughput and reduces the average end-to-end delay to 27 and 90%, when the packet loss rate on each link is 35%. Moreover, the resource is fairly allocated to different flows. TCP-HONC is also capable of balancing load among different paths and the queue length on bottleneck links is stable. The throughput gain achieved by TCP-HONC is the result of re-encoding data at intermediate nodes and the derived delay reduction benefits from the one-hop ACK and retransmission scheme.