Outage and throughput performance of hybrid RISs-relay-aided-wireless systems with imperfect transceiver hardware

In this paper, we propose a wireless system where multiple advanced reconfigurable intelligent surfaces (RISs) are combined with a traditional relay for significantly enhancement the system performance. Unlike previous works where perfect transceiver hardware (PTH) was often assumed in the RISs-aided-wireless systems, imperfect transceiver hardware (ITH) is taken into consideration in this work. Applying mathematical analysis, we obtain the closed-form expressions of outage probability (OP) and throughput of the proposed hybrid RISs and relay aided wireless system with ITH (the hybrid RISs-relay-aided-ITH system). Based on these expressions, it is easy to derive the OP and throughput expressions of hybrid RISs-relay-aided-wireless system with PTH (the hybrid RISs-relay-aided-PTH system), RISs-aided-wireless systems with ITH and PTH (the RISs-aided-ITH/PTH systems), and relay-aided-wireless systems with ITH and PTH (the relay-aided-ITH/PTH systems). We confirm the accuracy of the derived formulas via Monte-Carlo simulations. Numerical illustrations clarify a significant impact of distortion noises due to the ITH on the OP and throughput of the hybrid RISs-relay-aided-ITH system, especially in high threshold and high transmission rate. Moreover, a great benefit of the RISs is confirmed because the OP and throughput performances of the hybrid RISs-relay-aided-ITH/PTH systems are dramatically higher than those of the relay-aided-ITH/PTH systems. On the other hand, the performance loss caused by high carrier frequency of WiFi systems are significant. Additionally, the specific effects of the positions of the RISs and relay, the threshold and transmission rate, and the numbers of reflecting elements (REs) on the OP and throughput of the hybrid RISs-relay-aided-ITH system are detailedly analyzed. © 2022 Elsevier GmbH