Power allocation scheme for maximizing spectral efficiency and energy efficiency tradeoff for uplink NOMA systems in B5G/6G

Non-orthogonal multiple access (NOMA) is one of the key potential technologies for beyond 5G, i.e., 6G, networks. However, power allocation for spectral efficiency (SE) and energy efficiency (EE) tradeoff for uplink NOMA systems is still an open problem. In this study, we investigate the power allocation problem to maximize SE–EE tradeoff for systems with multi-cluster multi-user applications. Firstly, the power allocation optimization problem is formulated with the constraints of power budget and the minimum rate required by each user. Then, the optimization problem is decomposed into a group of sub-problems, which aim to maximize the tradeoff of SE–EE for each cluster. Finally, these sub-problems are simplified and solved by using bisection method and monotonicity of function. Simulation results show that the proposed scheme achieves much higher SE–EE tradeoff than the existing schemes.