Energy Efficiency–Delay Tradeoff for a Cooperative NOMA System

The tradeoff between the energy efficiency (EE) and delay problem in the cooperative relaying system is studied by using non-orthogonal multiple access (NOMA) in this letter. To obtain an efficiency tradeoff between EE and delay, a stochastic-based EE optimization problem is formulated by considering the system queue stability. Then, the fractional programming and control parameter-based Lyapunov optimization method is proposed to solve the formulated problem. Furthermore, we derive the analytical bounds of EE and delay based on the control parameter. Finally, simulation results verify that the proposed cooperative NOMA system performs better than the traditional orthogonal multiple access cooperative system.