Non-orthogonal multiple access (NOMA) is a promising transmission scheme employed at the physical layer to improve the spectral efficiency. In this paper, we develop a novel cross-layer approach by employing NOMA at the physical layer and instantly decodable network coding (IDNC) at the network layer in downlink cellular networks. Following this approach, two IDNC packets are selected for each transmission, with one designed for all receivers and the other designed only for the strong receivers which can employ successive interference cancellation (SIC). The IDNC packets selection, transmission rates adaption for the two IDNC packets, and NOMA power allocation are jointly considered to improve the throughput of the network. Given the intractability of the problem, we decouple it into two separate subproblems, the IDNC scheduling which jointly selects the IDNC packets and the transmission rates with the given NOMA power allocation, and the NOMA power allocation with the given IDNC scheduling. The IDNC scheduling can be reduced to a maximum weight clique problem, and two heuristic algorithms named as maximum weight vertex (MWV) search and maximum weight path based maximum weight vertex (MWP-MWV) search are developed to solve the first subproblem. An iterative function evaluation (IFE) approach is proposed to solve the second subproblem. Simulation results are presented to demonstrates the throughput gain of the proposed approach over the existing solutions.

翻译：非正交多址接入（NOMA）是一种在物理层提高频谱效率的 promising 传输方案。本文提出了一种新颖的跨层方法，在蜂窝下行链路网络的物理层采用NOMA，在网络层采用即时可解网络编码（IDNC）。基于该方法，每次传输选择两个IDNC数据包，其中一个面向所有接收端，另一个仅面向能够使用串行干扰消除（SIC）的强接收端。为提升网络吞吐量，本文联合考虑了IDNC数据包选择、两个IDNC数据包的传输速率适配以及NOMA功率分配问题。鉴于问题的复杂性，我们将其分解为两个独立的子问题：在给定NOMA功率分配下联合选择IDNC数据包与传输速率的IDNC调度问题，以及在给定IDNC调度下的NOMA功率分配问题。IDNC调度可转化为最大权值团问题，为此开发了名为最大权值顶点（MWV）搜索和基于最大权值路径的最大权值顶点（MWP-MWV）搜索两种启发式算法以求解第一个子问题。针对第二个子问题，提出了迭代函数评估（IFE）方法。仿真结果表明，所提方法相较于现有方案具有显著的吞吐量增益。