Performance analysis of virtual full-duplex and underlay D2D based wireless systems

Abstract

The rapid increase in mobile device usage has triggered a surge in bandwidthintensive applications like video streaming, gaming, and more. This growth has heightened the demand for enhanced spectrum utilization and performance in upcoming wireless networks. Technologies such as virtual full-duplex (VFD) communication, underlay device-to-device (D2D) communication, reconfigurable intelligent surfaces (RIS) or intelligent reflecting surfaces, and non-orthogonal multiple access (NOMA) have emerged as promising solutions for the next generation of wireless networks. Traditional half-duplex systems, where devices can only transmit or receive at any given time, often underutilize available spectrum. Full-duplex (FD) communication overcomes this limitation by enabling simultaneous transmission and reception on the same frequency channel, effectively doubling spectral efficiency with reduced latency. However, due to the high self-interference problem in FD systems, VFD communication has emerged as an alternative with improved network performance. Furthermore, underlay D2D communication allows devices in close vicinity to communicate directly using the same frequency bands allocated to cellular networks with interference reduction techniques via proper resource allocation, thus improving spectrum utilization. Additionally, NOMA enables efficient sharing of time-frequency resources among multiple users. Unlike traditional orthogonal multiple access (OMA) schemes, NOMA allows multiple users to transmit concurrently on the same frequency band by employing power domain multiplexing. Moreover, RIS can improve signal propagation, coverage, and reliability by intelligently manipulating the electromagnetic waves. This enhancement leads to improved rates and efficiency in wireless communication systems. Additionally, a variant of RIS known as simultaneously transmitting and reflecting RISs (STAR-RIS) not only reflects signals but also transmits them, thereby enhancing the flexibility and effectiveness of RISs to serve users on both sides of the RIS.