An efficient network coding based multicast retransmission scheme for mobile communication networks with relays

This paper proposes a network coding based retransmission scheme for multicast in a mobile communication network with relay. The proposed retransmission scheme uses frequency division (FD) for resource allocation in order to achieve high transmission and retransmission efficiency in the network. Meanwhile, an efficient packet selection algorithm called Weight Pick is proposed to support the retransmission scheme. Unlike existing packet selection algorithms, Weight Pick introduces the new concept of the dynamic combination number in performing network coding. Based on this concept, a base station or a relay dynamically determines the number of packets combined or encoded in a retransmission packet based on the current packet receiving status and the combination number for each retransmission packet can be different. Simulation results show that the proposed retransmission scheme with Weight Pick can significantly improve the retransmission performance in terms of the packet loss ratio and the number of delivered packets as compared with existing network coding based retransmission schemes.