ARQ: The Gateway from NOMA to NOM

This work presents a new framework that utilizes

power-domain (PD) nonorthogonal multiple access (NOMA) as a multiplexing scheme to improve the throughput of point-to-point (P2P), or single user, communications. The proposed framework synergizes PD-NOMA and automatic repeat request (ARQ) to enable multiplexing and transmitting multiple packets that belong to the same user simultaneously. To overcome channel estimation and feedback limitations, and to reduce the system complexity, a simple adaptation scheme is proposed select the

appropriate number packets to be transmitted within a given

transmission slot. Moreover, the number of transmitted packets

is limited to a maximum of two to allow the receiver to blindly

identify the number of transmitted packets in a particular

transmission slot. The obtained results show that the proposed

NOM scheme can eventually double the system throughput at

high signal-to-noise ratios (SNRs), and hence, reduce the delay

by 50%. The system complexity and overhead are generally

comparable to conventional ARQ systems.