Hybrid Multiple Access Using Simultaneously NOMA and OMA This paper proposes a hybrid multiple access scheme using both nonorthogonal multiple access (NOMA) and orthogonal multiple access (OMA) to overcome the inherent problems of NOMA. In NOMA, as multiple access is performed within the power domain, a small difference in the channel gain between users or an increase in the number of simultaneous users reduces the effectiveness. To cope with these problems, the proposed scheme applies a novel combination of NOMA and OMA as well as NOMA for multiple access patterns, and then determines the best pattern based on the system capacity. The effectiveness of the proposed scheme is demonstrated in comparison with conventional hybrid multiple access using NOMA and OMA through computer simulations.

Performance Comparison Between NOMA and OMA Relaying Protocols in MultiHop Networks over Nakagamim Fading Channels under Impact of Hardware Impairments In this paper, we evaluate and compare performance of multihop relaying (MR) protocols under impact of hardware impairments, in terms of outage probability (OP) and throughput (TP). By applying nonorthogonal multiple access (NOMA) technique at each hop, the endtoend data ratethroughput of the MR protocol can be enhanced, as compared with the conventional one. Particularly, the transmitter at each hop combines two signals, and forwards the combined signal to the receiver which uses successive interference cancelation (SIC) to extract the data. For performance evaluation and comparison, we derive exact closedform expressions of OP and TP for the considered protocols over Nakagamim channel. Monte Carlo simulations are then performed to verify the theoretical derivations.