Efficient and Reliable Multicast Using Device-to-Device Communication and Network Coding for a 5G Network

How to achieve efficient reliable multicast with 100 percent reliability is an important issue of emerging 5G network. In the 5G network, besides the macro BSs, ultra-dense low-power BSs (e.g., micro, pico, and femto eNBs) are deployed throughout the macrocell to form ultradense small cells, which reduces the number of associated multicast receivers per BS and consequenly reduces the number of retransmissions per packet (i.e., traffic load) at each BS. However, this gain is greatly limited by the nodes with bad channel quality. Adopting D2D-communication- based retransmission can effectively reduce the retransmissions at the BSs. There are some challenging issues to be addressed, like the selection of appropriate D2D links, extremely reducing D2D retransmissions, and the design of an efficient acknowledgment mechanism. In this article, considering the ultra-dense small cell deployment in a 5G network, we propose an efficient reliable multicast scheme that jointly utilizes D2D communication and network coding to achieve 100 percent reliability. In addition to discussing research issues that deserve further study, we present numerical results to illustrate the performance gains achieved by applying the proposed scheme in terms of traffic load reduction at the BSs.