Performance of Multi-RIS-Assisted D2D Communication Using NOMA

Future 5G technologies increase spectrum efficiency and wireless capacity by supporting numerous connections at once. New designs are therefore required in order to support the future 5G vision. A desirable technique for beyond 5G, device-to-device (D2D) communication improves spectrum efficiency, capacity and lowers end-to-end latency as devices in close proximity interact directly with one another without using cellular infrastructure. As a result, the network needs a new, efficient D2D communication framework that can boost network performance. D2D communication with re-configurable intelligent surface (RIS) improves the performance of a communication network. In this work, a multi-RIS-assisted D2D communication using non-orthogonal multiple access (MRDN) network is studied. The proposed MRDN network model investigates the outage and throughput performance over Rician fading channels. Two possibilities are taken into consideration in this regard: (i) choosing the best received signal, and (ii) combining all received signals. Influence of imperfect successive interference cancellation (SIC) is explored to maintain practicability as NOMA is employed. In this regard, a thorough network modeling is carried out and new analytical formulas for the probability density function (PDF) of the equivalent channel and combined channel, outage, and throughput are developed. It is observed that combining of all received signals scenario performs better as compared to the other one. The impact of the number of RIS elements on the performance of the MRDN is significant. The performance of MRDN improves as the number of RIS increases. Performance of non-orthogonal multiple access (NOMA) scheme is also compared with the conventional orthogonal multiple access (OMA) scheme. Capacity gain is also investigated to test the superiority of NOMA over OMA.