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.

中文翻译：

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在 5G 网络中使用设备到设备通信和网络编码实现高效可靠的组播

如何实现100%可靠性的高效可靠组播是新兴5G网络的重要课题。在 5G 网络中，除宏基站外，超密集低功耗基站（如 micro、pico 和 femto eNB）遍布宏蜂窝，形成超密集小蜂窝，从而减少了每个 BS 的相关组播接收器数量，并因此，减少了每个 BS 的每个数据包的重传次数（即流量负载）。然而，这种增益受到信道质量差的节点的极大限制。采用基于 D2D 通信的重传可以有效地减少基站的重传。有一些具有挑战性的问题需要解决，例如选择适当的 D2D 链路、极大地减少 D2D 重传以及设计有效的确认机制。在本文中，考虑到 5G 网络中的超密集小基站部署，我们提出了一种高效可靠的组播方案，该方案联合利用 D2D 通信和网络编码来实现 100% 的可靠性。除了讨论值得进一步研究的研究问题外，我们还提供了数值结果来说明通过应用所提出的方案在 BS 减少流量负载方面所获得的性能提升。