Threshold-Based Selective Cooperative NOMA: Capacity/Outage Analysis and a Joint Power Allocation-Threshold Selection Optimization
Ferdi Kara, Hakan Kaya
Abstract
In this letter, we analyze ergodic capacity (EC) and outage probability (OP) for threshold-based selective cooperative non-orthogonal multiple access (TBS-C-NOMA) which has been proposed as a reliable alternative to conventional C-NOMA networks. We derive exact expressions for EC and OP in closed-forms and the theoretical analyses are validated via computer simulations. The trade-off for TBS-C-NOMA is raised where the data reliability (i.e., error rate) changes reversely with the EC and OP performances. Nevertheless, it is proved that TBS-C-NOMA provides a remarkable gain in data reliability compared to the decay in EC and OP. Finally, the optimization of power allocation (PA) is re-defined considering the trade-off in TBS-C-NOMA and a joint PA-threshold selection (TS) optimization is proposed in terms of capacity maximization under required data reliability.