Performance Analysis of RIS-assisted Full-Duplex Two-Way NOMA using iFBL and FBL Codes

This paper investigates the performance of reconfigurable intelligent surface (RIS) assisted full-duplex two-way (FDTW) non-orthogonal multiple access (NOMA) (RIS-FDTW-NOMA) systems under infinite block-length (iFBL) and finite block-length (FBL) transmission regimes. In this system, two users exchange their information simultaneously through NOMA with the help of RIS. To assess the system performance in the iFBL regime, we derived the analytical expression of outage probability (OP) and system throughput using the moment matching method and the Gauss-Chebyshev quadrature (GCQ) method. For FBL transmission, we derived the analytical expression of the average block error rate (ABLER) by using the GCQ method. We also obtained the expressions for system throughput, goodput, latency, and reliability from the ABLER expression. Monte Carlo simulations are performed to verify the accuracy of the analytical expressions. Numerical results reveal that our proposed system provided better OP, ABLER, and higher throughput than the RIS-aided two-way-orthogonal multiple access (RIS-TW-OMA) system.

I. Introduction

The advancement of wireless communication technologies and the proliferation of technology-driven Internet-of-Things (IoT) such as telesurgery, intelligent transportation, augmented reality, and wearable or e-health service applications in recent years have not only increased the demands placed on users for effective connection but also require high spectral efficiency (SE) and ultra-reliable and low-latency communication (URLLC) [1], [2]. To address these requirements, two interesting communication methods for B5G and 6G system design are reconfigurable intelligent surfaces (RISs) and non-orthogonal multiple access (NOMA). RIS can reconfigure the propagation environment of a mobile user proactively to improve data throughput and reception reliability [3]. NOMA has the potential to enhance spectral efficiency, facilitate extensive connectivity, promote user equity, and decrease transmission latency through the facilitation of dynamic spectrum sharing among mobile users and the strategic exploitation of their diverse channel conditions and quality-of-service (QoS) demands [4].