A Novel Resource Allocation Scheme for Underlaying NOMA-Based Multi-Channel Cognitive D2D Communications

In this paper, we investigate a non-orthogonal multiple access (NOMA)-based underlay multi-channel cognitive device-to-device (D2D) communications where secondary users (SU) are modeled as D2D users and can opportunistically access a licensed spectrum. We efficiently exploit a resource allocation scheme for the investigated model. A two-stage solution is used in which sub-channels (SCs) and powers are jointly assigned to the SU users and transmitters, respectively. Hence, a power control scheme to the primary users (PU) is considered and a power allocation and SC assignment is studied employing a convex optimization method to achieve the optimal parameters. We show that throughput of the SU transceivers can be maximized by optimal power and sub-channel (SC) allocations to the SU and primary users, subject to controlling total transmission power, interference power at the PUs, and minimum rate requirements of the users. We study the performance of the network by increasing the number of PUs and SCs. Moreover, minimum rate requirement and maximum allowed interference at the PUs versus sum rate of the SU transceivers is investigated. The simulation results present insights about the impact of the optimal power and SC allocations.