Energy-efficient power allocation for NOMA heterogeneous networks with imperfect CSI

In this paper, an optimal user power allocation scheme is proposed to maximize the energy efficiency for downlink nonorthogonal multiple access (NOMA) heterogeneous networks (HetNets). Considering channel estimation errors and interuser interference under imperfect channel state information (CSI), the energy efficiency optimization problem is formulated, which is nondeterministic polynomial (NP)hard and nonconvex. To cope with this intractable problem, the optimization problem is converted into a convex problem and address it by the Lagrangian dual method. However, it is difficult to obtain closedform solutions since the variables are coupled with each other. Therefore, a Lagrangian and subgradient based algorithm is proposed. In the inner layer loop, optimal powers are derived by the subgradient method. In the outer layer loop, optimal Lagrangian dual variables are obtained. Simulation results show that the proposed algorithm can significantly improve energy efficiency compared with traditional power allocation algorithms. © 2022, Beijing University of Posts and Telecommunications. All rights reserved.