Energy-Efficient Resource Allocation with Imperfect CSI in NOMA-based D2D Networks with SWIPT

Non-orthogonal multiple access (NOMA)-based device-to-device (D2D) network has attracted widespread attention since it can address the problem of spectrum shortage in the next-generation communication networks. However, the robust resource allocation problem in this network has not been well investigated. In this paper, we aim for maximizing the energy efficiency (EE) of a NOMA-based D2D network with simultaneous wireless information and power transfer technique under imperfect channel state information. The considered problem is modeled as a non-convex optimization problem that considers the maximum tolerable outage probability of each D2D user (DU), the successive interference cancellation decoding order, and the maximum transmit power of base station and DUs, where the transmit power, power splitting factor, and resource block assignment factor are jointly optimized. Since the formulated mixed-integer fractional programming problem with outage-probability constraints is non-convex and difficult to solve, we firstly transform it into a non-probabilistic problem through a relaxation approach, and then, transform it into a convex one by using the variable-substitution approach and Dinkelbach's method. Finally, an EE-based iterative algorithm is proposed to solve this intractable problem. Simulation results show that the proposed algorithm has a fast convergence and low outage probability.