Impact of Residual Hardware Impairment on the IoT Secrecy Performance of RIS-Assisted NOMA Networks

Abstract

Non-orthogonal multiple access (NOMA) technology is expected to effectively improve the spectrum efficiency of fifth-generation and later wireless networks. As a new technology, reconfigurable Intelligent surfaces (RIS) can achieve high spectral and energy efficiency with a low cost in wireless networks. These are achieved by integrating a great quantity of low-cost passive reflective units (RUs) on the plane. In this paper, in order to meet the needs of high efficiency, low power consumption, and wide coverage, we combine RIS-assisted NOMA technology with the internet of things (IoT). Because in the actual wireless communication system, the residual hardware impairment (RHI) characteristics of the actual transceiver equipment will have an important impact on system secrecy performance. Therefore, the study will propose a single eavesdropper RIS-assisted downlink NOMA system with RHI (E-RHI-RIS-NOMA). The study will also investigate the impact of RHI on the physical layer security (PLS) performance of the system and the closed-form expression of the user's secrecy outage probability (SOP) is derived. Finally, the simulation results show that 1) the main factors affecting the SOP are the quantity of RUs in RIS, the transmit SNR, and the target data rate, 2) it is proved that the hardware impairment of the transceiver harms the system's secrecy outage performance while the severity of the impact of RHI on the system performance depends on the transmit SNR and target data rate. Moreover, RHI at different nodes has a different influence on system secrecy performance. 3) the system performance of RIS relying on NOMA is improved compared with orthogonal multiple access (OMA) and conventional NOMA.

Reconfigurable Intelligent Surface Aided Multi-User Communications: State-of-the-Art Techniques and Open Issues

“…MIMO [56] RIS-Aided NOMA MIMO with noise cancellation system is designed which was able to eliminate the inter-cluster interference using a large number of RIS elements. Hardware Impairment effect [52], [53] Evaluated the performance of the system in terms of OP and SOP, in the presence of hardware impairments at the transceiver, where severe impact is shown and also compared NOMA with OMA system. Energy efficiency and optimization [55], [57], [59] Authors have focused on energy optimization and minimization of transmit power and proposed an iterative non-complex algorithm and machine learning approach, which was able to boost up the performance of suggested system by 23 percent.…”

“…Authors in [52] discussed the impact of Residual Hardware Impairments (RHI) on RIS-aided NOMA system. The research shows that RHI shows a primary impact on system secrecy performance.…”

“…To explore the impact of RHI on a RIS-aided NOMA system, [52], [53] studied two-user downlink NOMA, where each user is distinguished by the distance and position of the user. In this scenario, hardware impairments are considered as the residual noise either at the transmitter or the receiver or both, considering the real-time environment, which affects the performance of the system.…”

“…To raise the impact of imperfect hardware, the authors in [104] studied the transmission design for a RIS-aided secure MISO communication system in the presence of transceiver hardware impairments. In [37], the authors also examined the impact of RHI on system secrecy performance of RISassisted NOMA technology integrated with IoT. The authors derived an approximate closed-form expression of the user's SOP.…”

“…This becomes even more important as conventional relaying technology is unavailable in mmWave and THz frequency bands [33]. Moreover, the integration of RIS into multi-user communications provides advanced PLS of legitimate users in the presence of eavesdroppers [7], [32]- [37]. Thus, RIS is expected to achieve higher spectrum energy efficiency in future wireless communications.…”