TCPNC-DGSA: Efficient network coding scheme for TCP in multi-hop cognitive radio networks

Cognitive radio (CR) has emerged as a promising solution to enhance spectrum utilization. In CR networks (CRNs), the secondary users can opportunistically exploit frequency bands when the primary users (PUs) do not occupy the bands. In this communication paradigm, transmission control protocol (TCP) performance may suffer from significant degradation due to the features of CRNs. In this paper, we investigate the limitations of TCP in multi-channel multi-radio multi-hop CRNs, and propose a novel TCP called TCP Network Coding Dynamic Generation Size Adjustment (TCPNC-DGSA) based on network coding. We dynamically adjust generation size in network coding operation according to the wireless communication environment—Generation Round Trip Time. In the meanwhile, we modify the TCP mechanism to fit into CRNs, by considering spectrum sensing state, spectrum changing state and presence of PUs. The simulation results indicate that TCPNC-DGSA can significantly improve the network performance in terms of throughput, bandwidth efficiency and delay. To the best of our knowledge, TCPNC-DGSA is the first TCP for CRNs from a network coding perspective, which can guarantee a quality of service in terms of delay.