Efficient Reliable Transmission for Mixed Multicast and Unicast Flows

Since wireless links suffer from channel fading and interferences, reliable transmission is a challenging issue in wireless networks. Recently, it has been proven that network coding can greatly improve transmission efficiency, reliability and robustness of wireless networks in comparison with the conventional automatic repeat request (ARQ) schemes. However, existing network coding-based schemes for mixed multicast and unicast transmissions consider retransmission procedure as two independent parts, multicast part and unicast part. In this paper, we explore to use network coding for mixed multicast and unicast transmissions. We design a network coding based retransmission scheme that can combine the lost packets from both multicast and unicast flows so as to increase coding opportunity and thus improve network resource utilization. Experimental results show that our proposed approach outperforms the conventional methods in terms of the total number of retransmissions and thus improve bandwidth efficiency.