Mode Selection between Index Coding and Superposition Coding in Cache-Based NOMA Networks

By analytically showing that index coding (IC) is more power efficient than superposition coding (SC) when appropriate caching contents are available for a pair of users, we propose a sub-optimal joint user clustering and power allocation scheme for a single-cell downlink non-orthogonal multiple access network with caching memory at the receivers that alternate between IC and SC. Simulation studies demonstrate that the proposed scheme significantly reduces the transmission power when compared with the benchmark scheme that only allows SC.