Efficient network coding-based multicast retransmission mechanism for mobile communication networks

This study proposes a network Coding-based RETransmission (CoRET) mechanism for supporting multicast service in mobile communication networks. CoRET introduces deterministic network coding to improve retransmission efficiency and retransmission reliability. To support CoRET, a couple of efficient packet selection algorithms are proposed, one is called 'Most-Least' selection and the other is called Hamming distance-based ('Hamming-D') selection, to select packets when performing network coding for retransmission. Most-Least selects the packets with the most retransmission requests and the least retransmission requests, whereas Hamming-D selects the packets with the largest Hamming distance. Simulation results show that with Most-Least or Hamming-D CoRET outperforms an existing retransmission scheme, 'Random Pick', in terms of both retransmission efficiency and retransmission reliability. To achieve the best performance of the Hamming-D algorithm, a mathematical model is further developed to analyse the impact of the number of original packets encoded into a packet for retransmission on the retransmission performance to find an optimal encoding number that can achieve the best performance.