Broadcasting System with Cooperative NOMA and Successive Refinement

This paper proposes an efficient broadcasting system which combines cooperative non-orthogonal multiple access (CO-NOMA) and successive refinement (SR) coding. The objective is to construct uncorrelated descriptions of the same source information carried by different NOMA layers, such that each user can choose to decode only the basic description or both, depending on the quality-of-service (QoS) requirement. To enhance the performance of far NOMA users which demand a high QoS, user cooperation is invoked and two relaying schemes are proposed. Assuming all channels are suffered from block Rayleigh fading, the outage probabilities of the proposed system are mathematically derived in closed-form. The advantages over conventional NOMA and CO-NOMA are also demonstrated.