  This letter considers two groups of source nodes. Each group transmits
packets to its own designated destination node over single-hop links and via a
cluster of relay nodes shared by both groups. In an effort to boost reliability
without sacrificing throughput, a scheme is proposed, whereby packets at the
relay nodes are combined using two methods; packets delivered by different
groups are mixed using non-orthogonal multiple access principles, while packets
originating from the same group are mixed using random linear network coding.
An analytical framework that characterizes the performance of the proposed
scheme is developed, compared to simulation results and benchmarked against a
counterpart scheme that is based on orthogonal multiple access.
