Energy Efficiency of NOMA Network under Fast Fading Channel

For downlink non-orthogonal multiple access (NOMA) systems under fast time-varying fading channels, a power allocation scheme to maximize system energy efficiency (EE) is proposed. Based on satisfying the users’ quality of service (QoS), an optimization problem of power allocation among users that maximizes the system energy efficiency is established. Due to the fractional objective function and the non-convex constraints, the optimization problem is non-convex and it is difficult to obtain accurate solutions efficiently. First, we propose an iterative algorithm to solve the power allocation scheme that maximizes energy efficiency within a single subchannel, and then allocate power to users by bisection method. The simulation results show that the proposed scheme has good effect in EE and good convergence performance.