Research on resource allocation algorithm for NOMA system based on fairness and optimal energy efficiency

User grouping and power allocation are the key technologies of non-orthogonal multiple access (NOMA) system. In this paper, we consider the joint optimization of user grouping and power allocation to maximize the system energy efficiency while considering the fairness of users. Firstly, the user grouping algorithm based on channel differences is proposed by combining KM algorithm to improve user fairness. Secondly, the energy efficiency optimization problem under multiple constraints is established. The Lagrangian function and KKT conditions are used to obtain the optimal power allocation factor, and then the system energy efficiency is maximized through the iterative Lagrangian multiplier. Simulation results show that the proposed algorithm can effectively improve user fairness and system energy efficiency than the traditional resource allocation schemes.