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Summary: It has been confirmed by many scientists and industrial experts that intelligent reflecting surface (IRS) should be one of the key enabling technologies for sixth‐generation (6G) wireless networks. This paper analyzes the performance of an IRS‐aided full‐duplex (FD) amplify‐and‐forward wireless relay (AFR) network, where the IRS is exploited to enhance the quality of the channel from the source to the relay. We successfully derive the analytical expressions of outage probability (OP), achievable data rate (ADR), and symbol error probability (SEP) of the considered IRS‐FD‐AFR network over Rayleigh fading channel. The corresponding expressions of the IRS‐aided half‐duplex (HD) AFR (IRS‐HD‐AFR) system are also derived as a benchmark to compare. The results demonstrate that the performance of both IRS‐FD‐AFR and IRS‐HD‐AFR systems are greatly improved by increasing the number of reflecting elements (L) in the IRS. All derived expressions are validated by Monte Carlo simulations. [ABSTRACT FROM AUTHOR]

In this paper, we propose a full-duplex (FD) relaying system with multi-input multi-output (MIMO) with simultaneous wireless information and power transfer (SWIPT), where the communication from source to destination is assisted by a full-duplex decode-and-forward (DF) relay. The time switching (TS) protocol is used at the relay to harvest the energy of radio-frequency (RF) signals transmitted from the source. To improve both system performance and the amount of harvested energy, multiple antennas are used at source and destination. Transmit antenna selection (TAS) is employed at the source with an assumption that the feedback of channel state information (CSI) is outdated. Meanwhile, both selection combining (SC) and maximal ratio combining (MRC) techniques are applied at the destination. The closed-form expressions of the outage probability (OP), optimal throughput, and symbol error probability (SEP) are derived subject to the outdated CSI over Rayleigh fading channels. We also make a comparison between the performance of the proposed MIMO-FD relaying system with SWIPT and that of MIMO half-duplex (HD) relaying systems with and without SWIPT. The validity of derived mathematical expressions is verified by Monte-Carlo simulations. Numerical results show that the TAS/MRC scheme gives better system performance than the TAS/SC scheme. Moreover, higher energy harvesting time is needed to maximize the throughput than to minimize the OP. [ABSTRACT FROM AUTHOR]

In this article, multiple antennas are proposed to utilize the millimeter-wave (MW) communication in a full-duplex aerial relay drone (FD-ARD) multi-user non-orthogonal multiple access (NOMA) system. Notably, the transmit antenna selection (TAS) technique is also incorporated to yield a significant boost in the system performance and a noteworthy reduction in signal processing complexity at the user end. The mathematical formulas of outage probability (OP) and achievable capacity (AC) of the proposed system are derived under the effect of channel and system parameters that are recommended for the fifth generation (5G) standard and the beyond 5G (B5G) proposals. All derived formulas are validated by using Monte-Carlo simulations. Numerical results show that TAS offers a substantial advantage over the scenarios without TAS. This holds even in the presence of several adverse factors, including the attributes of NOMA, the residual self-interference (RSI) stemming from full-duplex (FD) transmissions, the utilization of high carrier frequencies within MW bands, and the elevated altitude of the drone. The OP of systems equipped with TAS remains impressively below 1 0 − 11 , whereas systems lacking TAS exhibit a substantially higher OP value of 1 0 − 4 . Furthermore, the AC is notably elevated with the incorporation of TAS, as compared to scenarios where TAS is absent. However, the gap between the performance of the systems with and without TAS becomes insignificant when the RSI is sufficiently high. Consequently, this work can recommend the suitable transmit power corresponding to a specific RSI level and other system requirements to save energy and avoid saturated performance. In addition, the specific effect of high carrier frequencies in MW bands, positions of the drone, numbers of transmit/receive antennas, and RSI levels are deeply investigated to achieve useful insights into the behaviors of the proposed system. [ABSTRACT FROM AUTHOR]

This article considers millimeter-wave (mmWave) communications in a full-duplex (FD) unmanned aerial vehicle (UAV) system with multiple non-orthogonal multiple access (NOMA) users. In particular, a UAV operates in an FD transmission mode and acts as a decode-and-forward (DF) relay to aid communications between a ground base station and multiple ground users. Unlike previous works on the UAV-aided NOMA systems, where the specific carrier frequencies are often ignored, this work investigates the effect of a specific carrier frequency in the mmWave band and the channel model proposed for the fifth and beyond generations (5G and B5G) of mobile communications. The closed-form expressions of outage probability (OP) and achievable data rate (ADR) of the FD-UAV-NOMA system with mmWave communications (called as the MW-FD-UAV-NOMA system) are successfully derived over Nakagami- m fading channels. Numerical results clearly indicate the strong effects of the residual self-interference (RSI), high frequency, far distances between transmitters and receivers, wide bandwidth, and the altitude of the UAV on the OP and ADR of the MW-FD-UAV-NOMA system. Since the mmWave communications are used, an increase in the frequency, distances, bandwidth, and/or altitude of the UAV will significantly reduce the performance of the MW-FD-UAV-NOMA system. Importantly, when the UAV flies nearer the base station, the performance of the MW-FD-UAV-NOMA system can be better than when the UAV flies nearer the users. Finally, the exactness of the obtained expressions is confirmed via Monte-Carlo simulations. [ABSTRACT FROM AUTHOR]

In this paper, we investigate the detection performance for MIMO signals in a wireless full-duplex (FD) relaying network, in which the diversity techniques, including maximal ratio transmission (MRT) at source and maximal ratio combining (MRC) at destination, are applied. Especially, we rigorously study the impact of hardware impairment (HI) at all nodes and the residual self-interference (RSI) at the FD relay (FDR), which have not mentioned in previous works. Here, the closed-form expressions of key performance factors such as outage probability (OP), throughput, and symbol error rate (SER) of the considered MIMO-FDR system with HI are derived mathematically. All analytical expressions are validated by Monte Carlo simulations. Numerical results demonstrate a strong impact of HI on OP, throughput, and SER of the MIMO-FDR system in comparison with the ideal (ID) MIMO-FDR system, especially at high data rate. The combination of HI and RSI prevents OP and SER of the MIMO-FDR system from going lower than some error floors even at high signal-to-noise ratio (SNR) regime. However, by using MRT/MRC techniques with larger number of transmit antennas at source than the number of receive antennas at destination, the OP and SER performance in HI condition can be significantly improved. [ABSTRACT FROM AUTHOR]

Imperfect channel state information (I-CSI) and imperfect transceiver hardware often happen in wireless communication systems due to the time-varying and random characteristics of both wireless channels and hardware components. The impacts of I-CSI and hardware impairments (HI) reduce not only the system performance but also the self-interference cancellation (SIC) capability of full-duplex (FD) devices. To investigate the system performance in realistic scenarios, in this paper, we consider the performance of an FD multiple-input multiple-output (MIMO) relay system under the effects of I-CSI, imperfect SIC (I-SIC), and imperfect transceiver hardware. We mathematically derive the exact closed-form expressions of the outage probability (OP) and ergodic capacity of the considered HI-FD-MIMO relay system over Rayleigh fading channels with the existence of I-CSI, I-SIC, and HI. Numerical results indicate that the performance in terms of OP and capacity reaches saturation faster, especially when the channel estimation error, the residual self-interference (RSI), and HI levels are remarkable. Therefore, various solutions for effectively reducing the channel estimation error, RSI, and HI levels in the HI-FD-MIMO relay system should be carried out to improve the system performance. All derived mathematical expressions are verified through Monte-Carlo simulations. [ABSTRACT FROM AUTHOR]

Full-duplex (FD) communication and spatial modulation (SM) are two promising techniques to achieve high spectral efficiency. Recent works in the literature have investigated the possibility of combining the FD mode with SM in the relay system to benefit their advantages. In this paper, we analyze the performance of the FD-SM decode-and-forward (DF) relay system and derive the closed-form expression for the symbol error probability (SEP). To tackle the residual self-interference (RSI) due to the FD mode at the relay, we propose a simple yet effective power allocation algorithm to compensate for the RSI impact and improve the system SEP performance. Both numerical and simulation results confirm the accuracy of the derived SEP expression and the efficacy of the proposed optimal power allocation. [ABSTRACT FROM AUTHOR]

In this paper, we analyze the performance of a full-duplex (FD) amplify-and-forward (AF) relay system under various cases of relaying gains and channel state information conditions. Specifically, we consider the case that the FD relay node uses either fixed or variable gain for relaying under perfect and imperfect channel state information (CSI). For the case of imperfect CSI (I-CSI), we derive the exact expressions for the outage probability (OP), throughput, and symbol error probability (SEP) of the considered system. For the case of perfect CSI (P-CSI), we can provide approximate expressions of OP, throughput, SEP, and ergodic capacity. We also propose an effective power allocation scheme for the FD relay node to reduce the effect of residual self-interference (RSI). Both analytical and simulation results show a significant impact of RSI on the system performance. In particular, when RSI is small the variable-gain relaying can provide better performance than the fixed gain. However, when RSI becomes large these two relaying schemes have similar performance. In this situation, using the proposed optimal power allocation scheme can improve the system performance, especially for the case with weak direct link. [ABSTRACT FROM AUTHOR]