Outage Performance of Cooperative Underlay Cognitive Radio Relay Based NOMA Networks with Energy Harvesting Capability
Subject Areas : Wireless Network
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Keywords: NOMA-Cognitive Network, SIC Technique, Network Throughput, Convex Optimization Method, Probability of Outage,
Abstract :
In this work, Non-orthogonal multiple access (NOMA) technology is considered in cognitive radio (CR) networks in which the secondary users can only access the utilized spectrum of the primary user such that the primary user can tolerate the interference created by the secondary network. On the other words, the combination of CR and NOMA (CR-NOMA) is a novel concept to enhance the spectrum efficiency and the reliability of the network communication. The relaying technology with capability of energy harvesting is also considered which can improve the outage performance. In this scheme, the proper relay harvests energy from the secondary transmitter while it transmits the data of the secondary transmitter to the corresponding receiver. With this regard, the network throughput is improved in outage behavior and imperfect successive interference cancellation (SIC) condition at two users. Hence, the proposed problem is maximizing the performance of the network by proper selection of the relay for data transmission, setting the transmission power of the selected relay and optimal power allocation coefficients to each user with constraints on the outage probability and the interference in the primary user communication. For solving the problem, an iterative low complexity algorithm is proposed using the convex optimization scheme and Karush–Kuhn–Tucker conditions to select the best relay for transmission and users’ power allocation coefficients and also set the transmission power of the selected relay. Simulation results verify the effectiveness of the proposed algorithm for increasing almost 30 percent of the network performance in comparison to the bench mark algorithms in different conditions.