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This paper introduced a network throughput optimization method for interference and joint power control to address channel interference management and power control challenges within constrained unmanned systems. The method aimed to achieve maximum efficiency in overall energy utilization, frequency efficiency, and system performance. By examining the different duplex operation modes of the primary node in unmanned systems, the paper analyzed three types of interference: interlayer, intralayer, and mixed-type interference. It conducted a comprehensive assessment of Doppler frequency shifts, external interference effects, and signal-to-noise ratio estimations for cross-layer, intralayer, and mixed-layer interferences, deriving corresponding signal-to-noise ratio relationships. In addition, to mitigate interference and reduce energy consumption, this paper proposed a network throughput model based on power control and interference. It developed two centralized iterative methods and three distributed intelligent strategies to address the complex non-convex optimization problem. Simulation results demonstrate that the method maintains a balanced relationship between the number of unmanned systems, node antennas, and network capacity, leading to improved spectrum utilization and enhanced anti-interference transmission capabilities within unmanned systems. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Chongqing University of Posts & Telecommunications (Natural Science Edition) is the property of Chongqing University of Posts & Telecommunications and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Cellular vehicle-to-everything (C-V2X) is a promising area for research in wireless communication as it provides an improved performance for safe connectivity of autonomous vehicles over half duplex (HD) Direct Short Range Communication (DSRC) in terms of range, reliability and infrastructure cost. In this work, full duplex (FD) communication for Base Stations (BSs) over shared channels is presented for the first time in C-V2X networks. Three modes, Mode A, B and C have been defined based on autonomous, cellular HD and cellular FD communication. Network model has been built by plotting vehicles, pedestrians and traffic infrastructure according to Cox Process while BSs have been distributed according to 2-D Poisson Point Process (PPP) in a circular region. Mathematical model for success probability of FD communication over BSs in C-V2X networks using nearest neighbor criterion has been developed and same is compared with HD communication. Analytical results have also been compared with system model using Monte Carlo simulations. For the very first time, we have shown that success probability of FD is comparable with that of HD communication in terms of signal to interference noise ratio (SINR) ranging from −40dB to 60dB, with less than 10% degradation in the range from −15dB to 10dB, which is minimal. Other network characteristics like intensities of vehicles, roads and BSs have also shown minimal degradation (less than 10%) in performance of FD as compared to HD for C-V2X network. Effect of imperfect self interference cancellation (SIC) for different values has also been presented to highlight significance of achieving perfect SIC for FD in C-V2X networks. [ABSTRACT FROM AUTHOR]

Abstract This paper proposes a power scaling (PS) technique aimed at mitigating the outage floor problem commonly encountered in multi-user full-duplex (FD) non-orthogonal multiple access (NOMA) systems. Two antenna modes denominated as adaptive antenna mode (AAM) and fixed antenna mode (FAM) are utilized in this work for L FD near users in close proximity. In addition, a combined method of selecting both antenna mode and near user integrated with PS is employed to improve the overall network performance. Moreover, a power allocation between the chosen near user and far user is considered. In the low-to-moderate power regions, by AAM and FAM, we achieve twice of full diversity gain and full diversity gain, respectively. The research presents mathematical expressions for deriving the average capacity and outage probability and supports the theoretical findings with simulation-based evidence. The results of this work show that PS method not only contributes to a greater spatial diversity but also leads to superior performance compared to traditional FD NOMA systems. Moreover, our proposed method overcomes the outage floor and capacity ceiling. Furthermore, the work can be developed to 6G massive MIMO technology in multi-user FD cooperative NOMA systems.

This study focuses on the performance of device-to-device (D2D) communications in underlay cellular networks by analyzing key metrics such as successful transmission probability, coverage probability, and throughput. Under the homogeneous Poisson point process (PPP) spatial distribution of full-duplex (FD)-D2D users in cellular networks, stochastic geometry tools are used to derive approximate expressions for D2D users’ coverage probability and throughput. In comparison to the conventional half-duplex (HD) communication mode, when the self-interference cancellation factor β reaches −95 dB, there is a substantial improvement in the throughput of FD-D2D users, nearly doubling their gain. Additionally, experimental results demonstrate that the Newton iterative algorithm can be used to optimize the targeted signal-to-interference-plus-noise-ratio (SINR) threshold of users within the range of (10, 20) dB. [ABSTRACT FROM AUTHOR]

This paper proposes a power scaling (PS) technique aimed at mitigating the outage floor problem commonly encountered in multi-user full-duplex (FD) non-orthogonal multiple access (NOMA) systems. Two antenna modes denominated as adaptive antenna mode (AAM) and fixed antenna mode (FAM) are utilized in this work for L FD near users in close proximity. In addition, a combined method of selecting both antenna mode and near user integrated with PS is employed to improve the overall network performance. Moreover, a power allocation between the chosen near user and far user is considered. In the low-to-moderate power regions, by AAM and FAM, we achieve twice of full diversity gain and full diversity gain, respectively. The research presents mathematical expressions for deriving the average capacity and outage probability and supports the theoretical findings with simulation-based evidence. The results of this work show that PS method not only contributes to a greater spatial diversity but also leads to superior performance compared to traditional FD NOMA systems. Moreover, our proposed method overcomes the outage floor and capacity ceiling. Furthermore, the work can be developed to 6G massive MIMO technology in multi-user FD cooperative NOMA systems. [ABSTRACT FROM AUTHOR]

In this paper, we mathematically investigate a downlink non-orthogonal multiple access (NOMA) system for short-packet communications (SPC) in which the near users are used as full-duplex (FD) relays to forward intended signals from the source to a far user. In addition, partial relay selection is employed to enhance the performance of the FD relays under the impact of imperfect interference cancellation. At the far user, selection combining (SC) or maximal ratio combining (MRC) is employed to combine the signals received from the source and the selected FD relay. The analytical expressions for the average block error rate (BLER) of two users over flat Rayleigh fading channels are derived. Furthermore, closed-form asymptotic expressions of the average BLERs at the near and far users in high signal-to-noise ratio (SNR) regimes are obtained. The numerical results show that the analytical BLERs of the near user and far user closely match the simulation results.

Recently, reconfigurable intelligent surfaces (RISs) have attracted increasing attentions in the design of full-duplex (FD) systems due to their novel capability of propagation environment reconfiguration. However, in conventional RIS-assisted FD systems, the beamforming for self-interference cancellation (SIC) and sum rate maximization (SRM) are highly coupled during RIS optimization, which significantly degrades the system performance. To tackle this issue, we exploit a novel bilayer intelligent omni-surface (BIOS) structure in FD systems. Compared with the conventional RIS designs, the BIOS provides independent beams on both sides, thus enabling more flexible achievement of SRM and SIC. For the BIOS-assisted FD system, we first formulate an optimization problem to achieve SRM and efficient SIC simultaneously. Then, we exploit the relationship between the SRM and mean square error (MSE), and propose a weighted MSE minimization with SIC algorithm to solve the problem. Specifically, we jointly design the beamforming at the base station and the BIOS with manifold optimization while guaranteeing an SIC constraint. Furthermore, we theoretically derive a lower band for the BIOS size required for efficient SIC in FD systems. Simulation results indicate that the BIOS outperforms the conventional RIS designs in FD systems, and verify the accuracy of the derived lower bound for the BIOS size. [ABSTRACT FROM AUTHOR]

In this paper, a new methodology is developed for modeling and analyzing a full-duplex UAV-assisted relay system to facilitate solving the problems of UAV energy constraints and the vulnerability of UAVs to eavesdropping in the air. Combining simultaneous wireless information and power transfer (SWIPT) technology, we model the downlink UAV eavesdropping channel and propose a secure transmission protocol for a full-duplex UAV-assisted relay system. Using this transmission protocol, we analyze and derive the connectivity and security of the entire communication link, including connection probability and lower bounds on secrecy outage probability. A key intermediate step in our analysis is to derive the signal-to-digital noise ratio of the destination and eavesdropping nodes of the full-duplex UAV relay link. The analyses show that the power allocation factor λ is a trade-off between system connectivity and security, while greater eavesdropping interference needs to be sacrificed for an equal magnitude of security performance improvement under high security demand conditions. [ABSTRACT FROM AUTHOR]

Unmanned aerial vehicle (UAV) communications have gained recognition as a promising technology due to their unique characteristics of rapid deployment and flexible configuration. Meanwhile, device-to-device (D2D) and full-duplex (FD) technologies have emerged as promising methods for enhancing spectral efficiency and offloading traffic. One significant advantage of UAVs is their ability to partition suitable D2D pairs to increase cell capacity. In this paper, we present a novel network model in which UAVs are considered D2D pairs underlaying cellular networks, integrating FD into the communication links between UAVs to improve spectral efficiency. We then investigate a resource allocation problem for the proposed FD-UAV D2D underlaying structure model, with the objective of maximizing the system's sum rate. Specifically, the UAVs in our model operate in full-duplex mode as D2D users (DUs), allowing the reuse of both the uplink and downlink subcarrier resources of cellular users (CUs). This optimization challenge is formulated as a mixed-integer nonlinear programming problem, known for its NP-hard and intractable nature. To address this issue, we propose a heuristic algorithm (HA) that decomposes the problem into two steps: power allocation and user pairing. The optimal power allocation is solved as a nonlinear programming problem by searching among a finite set, while the user pairing problem is addressed using the Kuhn–Munkres algorithm. The numerical results indicate that our proposed FD-MaxSumCell-HA (full-duplex UAVs maximizing the cell sum rate with a heuristic algorithm) scheme for FD-UAV D2D underlaying models outperforms HD-UAV underlaying cellular networks, with improved access rates for UAVs in FD-MaxSumCell-HA compared to HD-UAV networks. [ABSTRACT FROM AUTHOR]

With the increasing demand for data exchange between nearby devices in proximity-based services, enhancing the security of wireless mutual broadcast (WMB) networks is crucial. However, WMB networks are inherently vulnerable to eavesdropping due to the open broadcast nature of their communication. This paper investigates the improvement of secrecy performance in random-access-based WMB (RA-WMB) networks by integrating physical layer security (PLS) techniques with hybrid duplex (HBD) operations under a stochastic geometry framework. The HBD method balances half-duplex (HD) receiving and full-duplex (FD) transceiving, utilizing self-interference cancellation (SIC) to enhance PLS performance. Key operational parameters, including transmission probability (TxPr), friendly jammer density, and conditions for FD operation, are designed to maximize secrecy performance. The analytical and numerical results demonstrate significant improvements in PLS performance, with SIC playing a critical role, particularly in scenarios with dense legitimate nodes, and with TxPr adjusted to balance HD receiving and FD transceiving based on SIC imperfections. The proposed design principles provide a comprehensive framework for enhancing the security of WMB networks, addressing the complex interplay of interference and SIC in various network configurations. [ABSTRACT FROM AUTHOR]

In this paper, we mathematically investigate a downlink non‐orthogonal multiple access (NOMA) system for short‐packet communications (SPC) in which the near users are used as full‐duplex (FD) relays to forward intended signals from the source to a far user. In addition, partial relay selection is employed to enhance the performance of the FD relays under the impact of imperfect interference cancellation. At the far user, selection combining (SC) or maximal ratio combining (MRC) is employed to combine the signals received from the source and the selected FD relay. The analytical expressions for the average block error rate (BLER) of two users over flat Rayleigh fading channels are derived. Furthermore, closed‐form asymptotic expressions of the average BLERs at the near and far users in high signal‐to‐noise ratio (SNR) regimes are obtained. The numerical results show that the analytical BLERs of the near user and far user closely match the simulation results. [ABSTRACT FROM AUTHOR]

In this article, we analyze the downlink transmission of a wirelessly powered hybrid cooperative non-orthogonal multiple access (C-NOMA) system relying on reconfigurable intelligent surfaces (RIS), where self-interference related to full-duplex (FD) and power efficiency are also considered. The network contains a single-antenna base station (BS), a RIS with many reflecting elements, a power beacon, and two users that can function in FD in comparison with the benchmark, i.e. half-duplex mode. In the proposed system, there are two communication paths from the BS to the far-user either through the RIS or via a near-user employing energy-harvesting from a power beacon. To comprehend the performance of the proposed system, we study and compare the outage probability under various parameters of interest such as power allocation coefficients, energy harvesting coefficients, number of RIS reflecting elements, and transmission rates. We aim to show the trade-off between these main parameters and system outage performance. Moreover, to highlight the advantages of the wireless-powered RIS-aided CNOMA system, we compare it against with benchmark, i.e. a wireless-powered RIS-aided cooperative orthogonal multiple access (C-OMA) system. All derived closed-form outage expressions are verified by employing Monte-Carlo simulations. Numerical results show that: (1) wireless powered RIS-aided FD C-NOMA is superior to the wireless-powered RIS-aided FD C-OMA in terms of outage probability in the high signal-to-noise ratio (SNR) region; and (2) in delay-to-tolerant transmission scenarios, the energy efficiency of the proposed wireless powered RIS FD C-NOMA outperforms the wireless powered RIS FD C-OMA in the high SNR region. [ABSTRACT FROM AUTHOR]

This paper presents a two-port microstrip patch antenna system with compact size and high isolation for full-duplex and multiple-input-multiple-output (MIMO) applications. The proposed miniaturization approach is to employ compact microstrip patch antenna and decoupling network as well. Here, two quarter-wavelength patch antennas are arranged in the H-plane coupled configuration with element spacing of about 0.008 λ at the center operating frequency. Besides, a defected ground structure is chosen as the decoupling network, which doesn't require any additional space and contributes to significantly reducing the overall antenna dimensions. The final antenna design with compact size of 0.49 λ × 0.37 λ × 0.01 λ has operating band from 2.45 to 2.48 GHz, in which isolation is better than 30 dB and the maximum isolation is 42 dB. Besides, the proposed antenna also achieved comparable gain of 3.8 dBi and good diversity performance. In comparison with other related works, the proposed design has smallest overall size with extremely small element spacing while obtaining comparable isolation enhancement.

In this research work QoS optimization issue while power division in with full-duplex enable transfer capability in the presence of a direct connection. A novel system model for power division based relaying system with full-duplex capability and a strategy that employs techniques such as consecutive interference cancellation. They also use the existing system to define the channel capacity alleviation issue. Then, using the suggested repeated power division ratio method and the planned information architecture, the defined issue is solved. FDBPT created a Power dividing based relaying technology with FD Decode and forwarding capability in this research paper, taking into account the existence of a direct connection. Then, to solve the spectrum efficiency optimization model, information decoding strategy based on SIC and MRC algorithms was presented to decipher signals from the destination node. An IPDP methodology was presented in the proposed way to solve the stated enormous performance maximizing issue. The proposed information decoding technique takes into account the benefits of direct connection, FD, and SIC. Furthermore, a number of simulations demonstrate the higher performance of the proposed approach. NS2 simulations are used to attain higher performance than previous techniques.

Simultaneous wireless information and power transfer (SWIPT) is a method through which users can simultaneously obtain energy and receive data from the base station (BS). This allows them to charge their batteries, which have limited power capacity, and enhance the quality of service (QoS). Nevertheless, this technology encounters the double near-far issue, where users located at the edges of the cell experience insufficient energy due to energy path loss, resulting in a decrease in system performance. In this investigation, we integrate the self-energy recycling technology with a D2D communication system that enables full-duplex operation. By employing this technology, the D2D cell edge user (DCEU) can harvest energy from self-interference and utilize it to transmit data to the nearest D2D cell center user (DCCU). The DCCU combines its data with the DCEU and sends it to the BS using uplink non-orthogonal multiple access (NOMA). Both the DCCU and DCEU use a significant amount of energy when transmitting data, which negatively affects the quality of service (QoS). The goal of this research is to decrease the overall energy consumption of the DCEU and DCCU while maintaining their QoS. The defined problem is complex due to time and power limitations, as well as the presence of self and NOMA interference. To address this issue, we utilize a technique that combines time and power allocation. The numerical results demonstrated that the proposed scheme consumes 28.12% and 40.67% lesser amount of energy as compared to the baseline schemes.

Summary: This paper considers a dual‐hop cooperative relay‐based communication with uplink (UL) and downlink (DL) non‐orthogonal multiple access (NOMA), where communication between sources to destinations takes place parallelly in the same frequency band over a Rayleigh fading channels. The energy harvesting (EH)‐based full‐duplex (FD) relay helps in forwarding the message from the source node to the destination node via superposition coding, thus calling it a multiple sources full‐duplex energy‐harvesting cooperative relay NOMA (MS‐FD‐EH‐CR‐NOMA) system. Early works focus on EH from one source node or a dedicated power station. In this article, the communication between sources and destinations occurs in two slots where first slot deals with energy harvesting while in second slot information transmission occurs. We studied the effect of imperfect successive interference cancellation (ipSIC) and residual self‐interference (RSI) in decoding the message at the relay and the destinations. We derived the closed‐form expressions for the outage probability of each pair and the system outage probability of the MS‐FD‐EH‐CR‐NOMA system. Next, we derive the closed‐form expressions of ergodic capacity under Rayleigh distributed fading channels. Further, numerical results are validated by its simulation results using Monte Carlo simulations in MATLAB. The results obtained through this work are a good step towards designing multiple source–destination communication using NOMA and EH relay. [ABSTRACT FROM AUTHOR]

In this research work QoS optimization issue while power division in with full-duplex enable transfer capability in the presence of a direct connection. A novel system model for power division based relaying system with full-duplex capability and a strategy that employs techniques such as consecutive interference cancellation. They also use the existing system to define the channel capacity alleviation issue. Then, using the suggested repeated power division ratio method and the planned information architecture, the defined issue is solved. FDBPT created a Power dividing based relaying technology with FD Decode and forwarding capability in this research paper, taking into account the existence of a direct connection. Then, to solve the spectrum efficiency optimization model, information decoding strategy based on SIC and MRC algorithms was presented to decipher signals from the destination node. An IPDP methodology was presented in the proposed way to solve the stated enormous performance maximizing issue. The proposed information decoding technique takes into account the benefits of direct connection, FD, and SIC. Furthermore, a number of simulations demonstrate the higher performance of the proposed approach. NS2 simulations are used to attain higher performance than previous techniques. [ABSTRACT FROM AUTHOR]

Simultaneous wireless information and power transfer (SWIPT) is a method through which users can simultaneously obtain energy and receive data from the base station (BS). This allows them to charge their batteries, which have limited power capacity, and enhance the quality of service (QoS). Nevertheless, this technology encounters the double near-far issue, where users located at the edges of the cell experience insufficient energy due to energy path loss, resulting in a decrease in system performance. In this investigation, we integrate the self-energy recycling technology with a D2D communication system that enables full-duplex operation. By employing this technology, the D2D cell edge user (DCEU) can harvest energy from self-interference and utilize it to transmit data to the nearest D2D cell center user (DCCU). The DCCU combines its data with the DCEU and sends it to the BS using uplink non-orthogonal multiple access (NOMA). Both the DCCU and DCEU use a significant amount of energy when transmitting data, which negatively affects the quality of service (QoS). The goal of this research is to decrease the overall energy consumption of the DCEU and DCCU while maintaining their QoS. The defined problem is complex due to time and power limitations, as well as the presence of self and NOMA interference. To address this issue, we utilize a technique that combines time and power allocation. The numerical results demonstrated that the proposed scheme consumes 28.12% and 40.67% lesser amount of energy as compared to the baseline schemes. [ABSTRACT FROM AUTHOR]

Abstract This paper presents a Highly Isolation open-loop resonators (OLR)—based microstrip full-duplex Tx/Rx antenna systems with low insertion loss for contemporary wireless system applications. Through a T-junction combiner, the proposed diplexer is accomplished by combining two OLR—based band-pass filters tuned at two distinct frequencies. The system is implemented on a Rogers TMM4 substrate with a loss tangent of 0.002, a dielectric constant of 4.7, and a thickness of 1.52 mm. The suggested full duplex has dimensions of (90 × 70) mm2. It achieves a modest frequency space ratio of R = 0.1646 in both transmit and receive modes by having two resonance frequencies of $${f}_{t}$$ f t = 2.191 GHz and $${f}_{r}$$ f r = 2.584 GHz, respectively. The simulated structure displays good insertion losses (IL) of approximately 1.2 dB and 1.79 dB for the two channels, respectively, at fractional bandwidths of 1.24% at 2.191 GHz and 0.636% at 2.584 GHz. The simulated isolation values for 2.191 GHz and 2.584 GHz are 53.3 dB and 66.5 dB, respectively.

This article presents a thorough investigation into the contrasting dynamics of full-duplex and half-duplex communication within the framework of visible light communication (VLC) networks compliant with the IEEE 802.15.7 standard. The main contributions of this research deal with Field Programmable Gate Array (FPGA) implementation, experimental data acquisition, interference evaluation, and performance assessment. In particular, the study delves into implementing both full-duplex and half-duplex communication schemes using FPGA technology for vehicular communications compliant to the IEEE 802.15.7 standard. Full-duplex is obtained by simultaneously transmitting over the same optical channel, without any multiplexing or access division strategy. Through experimental data acquisition, the paper provides a detailed comparison of the two communication schemes, shedding light on their respective strengths and limitations. Furthermore, the paper introduces an interference evaluation framework, which contributes to the understanding of the real benefits of full-duplex VLC through theoretical modeling of the interference and experimental validation. The performance evaluation section quantifies key metrics, allowing for a comprehensive assessment of the overall efficacy of full-duplex and half-duplex VLC systems in a vehicular network context. This research offers a perspective on the practical implications and trade-offs associated with adopting either half- and full-duplex VLC communication paradigm, paving the way for informed decision-making in the design and deployment of intelligent transportation systems (ITS) based on IEEE 802.15.7 networks.

This article proposes an approach to circular polarization conversion using two anisotropic frequency selective surfaces in a frequency-duplex system. We focus on validating the proposed conversion topology from H-polarization to left-hand circular polarization in the forward channel at $f_{1}$ , and from right-hand circular polarization to V-polarization in the backward channel at $f_{2}$ , to enable full-duplex satellite communications. The multiconductor transmission line model is employed to characterize the properties of each unit cell and to express the required scattering parameters for each surface at frequencies $f_{1}$ and $f_{2}$ . The obtained scattering parameters are then realized using a cascade of two frequency selective surfaces. The first surface features a diagonal strip to convert the incident H-polarized field into its perpendicular V-polarized field at $f_{1}$ . The second surface, employing a dual-split-ring structure, functions as an anisotropic layer to transform the perpendicular component into circular polarization. Similarly, at $f_{2}$ , the reverse channel converts an incident right-hand circularly-polarized field into an V-polarized output field. The proposed approach has been validated in the X-band and tested for polarization transformation performance in a full-anechoic chamber. The experimental results demonstrate that each surface and the entire dual-frequency selective surface system effectively operate as a frequency-duplexer which enables simulatenous bidirectional communication with two orthogonal polarizations.

This paper is the first to investigate an Active RIS (ARIS)-assisted FD-NOMA system and to formulate a sum rate maximization problem. To address this problem, we propose an alternating optimization algorithm that combines semi-definite relaxation (SDR) and successive convex approximation (SCA) methods. This approach decomposes the original problem into several subproblems, iteratively solving one variable while keeping the others fixed. Specifically, we derive the optimal closed-form solution for the receive beamforming vectors at the BS and propose a method based on SCA and SDR to solve for the transmit beamforming vectors at the BS and the reflection matrix of ARIS. Additionally, the optimal transmit powers for all uplink users are obtained through an iterative algorithm. Simulation results demonstrate that the proposed FD-NOMA scheme significantly enhances the system sum rate compared to HD and OMA schemes. In comparison to passive RIS (PRIS), ARIS effectively mitigates the “double fading effect”, providing a 60%-150% improvement in the rate performance of the assisted communication system.

This work proposes a spiral filter-based diplexer antenna for dual-band full-duplex 5G application in C-band. The shared radiator is formed by a cross-shape Yagi-Uda antenna. The dual-band fullduplex characteristic is obtained by applying a diplexer with two different band-stop filters (BSFs) based on a high-order rectangular spiral-shaped open-stub filter. The proposed diplexer antenna is suitable for modern 5G full-duplex communication system applications with a small frequency ratio and high isolation between two ports by applying a Wilkinson power divider. The diplexer antenna is designed, fabricated, and measured, showing good performance of channel isolations of 27 dB/23 dB and the antenna gain of 4.7 dBi/4.2 dBi at two operation bands from 3.56 GHz to 3.68 GHz and from 3.72 GHz to 3.83 GHz covering the required 100 MHz maximum bandwidth in C-band while its frequency ratio is only 1.04. [ABSTRACT FROM AUTHOR]

The deployment of long-term evolution systems in an unauthorized spectrum provided a credible solution to manage accelerating network data traffic. Meanwhile, the distribution of spectrum on unlicensed bands creates severe interaction issues. Therefore, this paper proposed a novel listen-and-talk-based MAC (LAT-MAC) protocol to enhance secondary users' (SUs') access performance by implementing a full-duplex mechanism. The application of full-duplex methods efficiently neglects collision and improves spectrum utilization of unlicensed bands. For cognitive radio networks, utilizing these benefits of a full duplex, the proposed LAT-MAC protocol simultaneously executes transmission processes and spectrum sensing. The cognitive network users sense spectrum utilizing energy detectors. For enhanced energy detection, the type 2 fuzzy cooperative spectrum sensing (T2FCSS) technique is implemented. Moreover, to attain enhanced spectrum sensing performances with the negligence of power-throughput tradeoff and self-interference, the switching algorithm-based cognitive radio network (SA-CRN) is employed. The performances of the proposed protocol are analyzed using different metrics, and evaluation results illustrate that it achieves enhanced performance compared with existing techniques. [ABSTRACT FROM AUTHOR]

Copyright of Acta Scientiarum Naturalium Universitatis Sunyatseni / Zhongshan Daxue Xuebao is the property of Sun-Yat-Sen University and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Recently, reconfigurable intelligent surfaces (RISs) have attracted increasing attentions in the design of full-duplex (FD) systems due to their novel capability of propagation environment reconfiguration. However, in conventional RIS-assisted FD systems, the beamforming for self-interference cancellation (SIC) and sum rate maximization (SRM) are highly coupled during RIS optimization, which significantly degrades the system performance. To tackle this issue, we exploit a novel bilayer intelligent omni-surface (BIOS) structure in FD systems. Compared with the conventional RIS designs, the BIOS provides independent beams on both sides, thus enabling more flexible achievement of SRM and SIC. For the BIOS-assisted FD system, we first formulate an optimization problem to achieve SRM and efficient SIC simultaneously. Then, we exploit the relationship between the SRM and mean square error (MSE), and propose a weighted MSE minimization with SIC algorithm to solve the problem. Specifically, we jointly design the beamforming at the base station and the BIOS with manifold optimization while guaranteeing an SIC constraint. Furthermore, we theoretically derive a lower band for the BIOS size required for efficient SIC in FD systems. Simulation results indicate that the BIOS outperforms the conventional RIS designs in FD systems, and verify the accuracy of the derived lower bound for the BIOS size.

In this paper, a new methodology is developed for modeling and analyzing a full-duplex UAV-assisted relay system to facilitate solving the problems of UAV energy constraints and the vulnerability of UAVs to eavesdropping in the air. Combining simultaneous wireless information and power transfer (SWIPT) technology, we model the downlink UAV eavesdropping channel and propose a secure transmission protocol for a full-duplex UAV-assisted relay system. Using this transmission protocol, we analyze and derive the connectivity and security of the entire communication link, including connection probability and lower bounds on secrecy outage probability. A key intermediate step in our analysis is to derive the signal-to-digital noise ratio of the destination and eavesdropping nodes of the full-duplex UAV relay link. The analyses show that the power allocation factor λ is a trade-off between system connectivity and security, while greater eavesdropping interference needs to be sacrificed for an equal magnitude of security performance improvement under high security demand conditions.

With the increasing demand for data exchange between nearby devices in proximity-based services, enhancing the security of wireless mutual broadcast (WMB) networks is crucial. However, WMB networks are inherently vulnerable to eavesdropping due to the open broadcast nature of their communication. This paper investigates the improvement of secrecy performance in random-access-based WMB (RA-WMB) networks by integrating physical layer security (PLS) techniques with hybrid duplex (HBD) operations under a stochastic geometry framework. The HBD method balances half-duplex (HD) receiving and full-duplex (FD) transceiving, utilizing self-interference cancellation (SIC) to enhance PLS performance. Key operational parameters, including transmission probability (TxPr), friendly jammer density, and conditions for FD operation, are designed to maximize secrecy performance. The analytical and numerical results demonstrate significant improvements in PLS performance, with SIC playing a critical role, particularly in scenarios with dense legitimate nodes, and with TxPr adjusted to balance HD receiving and FD transceiving based on SIC imperfections. The proposed design principles provide a comprehensive framework for enhancing the security of WMB networks, addressing the complex interplay of interference and SIC in various network configurations.

This paper considers the secrecy performance of several schemes formulti-antenna transmission to single-antenna users with full-duplex (FD)capability against randomly distributed single-antenna eavesdroppers (EDs).These schemes and related scenarios include transmit antenna selection (TAS),transmit antenna beamforming (TAB), artificial noise (AN) from the transmitter,user selection based their distances to the transmitter, and colluding andnon-colluding EDs. The locations of randomly distributed EDs and users areassumed to be distributed as Poisson Point Process (PPP). We derive closed formexpressions for the secrecy outage probabilities (SOP) of all these schemes andscenarios. The derived expressions are useful to reveal the impacts of variousenvironmental parameters and user's choices on the SOP, and hence useful fornetwork design purposes. Examples of such numerical results are discussed.

With the high demand for advanced services and the increase in the number of connected devices, current wireless communication systems are required to expand to meet the users' needs in terms of quality of service, throughput, latency, connectivity, and security. 5G, 6G, and Beyond (xG) aim at bringing new radical changes to shake the wireless communication networks where everything will be fully connected fulfilling the requirements of ubiquitous connectivity over the wireless networks. This rapid revolution will transform the world of communication with more intelligent and sophisticated services and devices leading to new technologies operating over very high frequencies and broader bands. To achieve the objectives of the xG networks, several key technology enablers need to be performed, including massive MIMO, software-defined networking, network function virtualization, vehicular to everything, mobile edge computing, network slicing, terahertz, visible light communication, virtualization of the network infrastructure, and intelligent communication environment. In this paper, we investigated the recent advancements in the 5G/6G and Beyond systems. We highlighted and analyzed their different key technology enablers and use cases. We also discussed potential issues and future challenges facing the new wireless networks. [ABSTRACT FROM AUTHOR]

In this paper, a hybrid full duplex (FD) and half duplex user relaying cooperative non orthogonal multiple access (NOMA) system is investigated which addresses the ergodic capacity problems with successive interference cancellation (SIC) technique. The residual self interference (RSI) exists due to imperfect self-interference cancellation. An advanced successive interference cancellation (ASIC) technique is introduced in the system to resolve the issues of unnecessary user decoding delay due to iterative decoding nature of SIC. The proposed scheme is implemented by mapping the received signal into number of subgroups. Then, the desired information signals are obtained by applying conventional SIC technique to each of these subgroups. The proposed system is characterized by deriving the closed form analytical expressions of ergodic capacities for NOMA users, energy efficiency and ergodic sum capacity under RSI. The analytical results are presented to show the effectiveness of the proposed system with ASIC over traditional system with SIC in terms of ergodic capacities for NOMA users, energy efficiency and ergodic sum capacity. Moreover, the energy efficiency and ergodic sum capacity of the proposed system also make it better than ASIC based FD NOMA system with dedicated relaying under same conditions. [ABSTRACT FROM AUTHOR]

This paper proposes a Self-interference (SI) cancellation system model of Underwater acoustic (UWA) communication for in-band full-duplex (IBFD) technology. The SI channel is separated from the Far channel by exploiting a concurrently orthogonal pilot channel estimation technique using two orthogonal frequency-division multiplexing (OFDM) blocks to establish orthogonality between them based on a unitary matrix. Compared to the half-duplex channel estimator, the mean squared error (MSE) and the bit error rate (BER) provided strong evidence for the efficiency of the proposed SI cancellation. Since full-duplex systems are more efficient than half-duplex ones, the proposed approach might be seen as a viable option for them. The proposed method proved effective when used with a fixed full-duplex (FD) position and FD shifting of up to 4°. Different channel lengths and distances are adopted to evaluate the proposed method. Initial findings indicate that MSE for the SI channel minimum mean-square error (MMSE) estimator at 20 dB is 0.118 · 10−3, for fixed FD. In addition, this paper presents a geometry channel model for the Far channel in the IBFD underwater communication system that describes the propagation delay of the multipath reflection. The simulation results for the multipath propagation delay spread are similar to the traditional results, with the delay spread of the suggested model reaching (79 ms), which is close to the Bellhop simulator result (78 ms).

Intelligent reflecting surfaces (IRS) have emerged as a promising technology to enhance the performance of wireless communication systems. By actively manipulating the wireless propagation environment, IRS enables efficient signal transmission and reception. In recent years, the integration of IRS with full-duplex (FD) communication has garnered significant attention due to its potential to further improve spectral and energy efficiencies. IRS-assisted FD systems combine the benefits of both IRS and FD technologies, providing a powerful solution for the next generation of cellular systems. In this manuscript, we present a novel approach to jointly optimize active and passive beamforming in a multiple-input-multiple-output (MIMO) FD system assisted by an IRS for weighted sum rate (WSR) maximization. Given the inherent difficulty in obtaining perfect channel state information (CSI) in practical scenarios, we consider imperfect CSI and propose a statistically robust beamforming strategy to maximize the ergodic WSR. Additionally, we analyze the achievable WSR for an IRS-assisted MIMO FD system under imperfect CSI by deriving both the lower and upper bounds. To tackle the problem of ergodic WSR maximization, we employ the concept of expected weighted minimum mean squared error (EWMMSE), which exploits the information of the expected error covariance matrices and ensures convergence to a local optimum. We evaluate the effectiveness of our proposed design through extensive simulations. The results demonstrate that our robust approach yields significant performance improvements compared to the simplistic beamforming approach that disregards CSI errors, while also outperforming the robust half-duplex (HD) system considerably.

Covert communications have arisen as an effective communications security measure that overcomes some of the limitations of cryptography and physical layer security. The main objective is to completely conceal from external devices the very existence of the link for exchanging confidential messages. In this paper, we take a step further and consider a scenario in which a covert communications node disguises itself as another functional entity for even more covertness. To be specific, we study a system where a source node communicates with a seemingly receive-only destination node which, in fact, is full-duplex (FD) and covertly delivers critical messages to another hidden receiver while evading the surveillance. Our aim is to identify the achievable covert rate at the hidden receiver by optimizing the public data rate and the transmit power of the FD destination node subject to the worst-case detection error probability (DEP) of the warden. Closed-form solutions are provided, and we investigate the effects of various system parameters on the covert rate through numerical results, one of which reveals that applying more (less) destination transmit power achieves a higher covert rate when the source transmit power is low (high). Since our work provides a performance guideline from the information-theoretic point of view, we conclude this paper with a discussion on possible future research such as analyses with practical modulations and imperfect channel state information. [ABSTRACT FROM AUTHOR]

This paper investigates the performance of cloud radio access networks (C‐RAN) in different power control scenarios in full‐duplex (FD) cellular networks. Results reveal that FD C‐RAN performance drastically reduces with uplink (UL) power control. We proposed a power control scheme in downlink (DL), which uplifts the UL user rate, but at the cost of DL rate. With UL and DL power control, the average rate saturates after a threshold number of base stations (BS) coordination and has little impact on coordinating additional BSs. Besides, the state‐of‐the‐art self‐interference suppression (SI) of 130 dB provides almost equal performance compared to the perfect SI cancelation. Hence co‐channel interference management becomes the bottleneck for FD system design. We used the Matern cluster process (MCP) to model the network. [ABSTRACT FROM AUTHOR]

In this paper, we analyze the performance of a full-duplex (FD) cooperative non-orthogonal multiple access (C-NOMA) relaying system with an amplify-and-forward (AF) protocol in the presence of loopback interference in FD transceivers. Particularly, by considering channel estimation errors and quantization noise in low-resolution analog-to-digital converters (ADCs), the accurate approximation expression for the ergodic rate and closed-form solution for the outage probability are derived, respectively. The validity of the theoretical results is verified by Monte Carlo simulations, which show that both channel estimation errors and quantization noise have deleterious effects on ergodic rate and outage performance for moderate and high signal-to-noise ratios (SNR). In the second phase of the C-NOMA system, both the outage performance and ergodic sum rate decrease at high SNRs due to the effects of loop interference. When the ADC dynamic range reaches a certain level, the system performance is more affected by loopback interference and channel estimation errors compared to the quantization noise of the ADCs. [ABSTRACT FROM AUTHOR]

With the dense deployment of basic service set (BSS) in the next generation Wireless Local Access Network (WLAN). The overlapping coverage of multiple BSSs leads to intensified contention conflicts, low efficiency of buffer state reports (BSR) collection and a sharp decline in system throughput. To solve this problem, this paper proposes an access point (AP) cooperation based multi-BSS multi-user full duplex multiple access protocol (CMMFD). Firstly, access control (AC) divides the STAs in the cooperative network area into overlapping STA and non-overlapping STA. A bi-level channel resource allocation algorithm is designed. The first level is channel resource allocation in the collection stage of BSR and inter-node interference information (BI), and the second level is channel resource allocation in full duplex data transmission. Secondly, a protocol framework for parallel BI information collection of cooperative APs is designed. AC schedules cooperative APs to send trigger frame at the same time, and triggers STAs in each BSS to report BI information on the assigned channel resource with p -probability access mode. Finally, AP forwards the collected BI information to AC, and AC assigns the STAs in the multi-BSS to perform multi-user full-duplex transmission on the resource unit (RU). Theoretical analysis gives the closed form expressions of the mean number of STAs successfully collected by AC in the cooperation area and saturated network throughput. Simulation results show that compared with MU-FuPlex and EnFD-OMAX protocol, CMMFD protocol improves the network throughput by 29.6% and 31.2% respectively. [ABSTRACT FROM AUTHOR]

This paper describes a hybrid half duplex (HD) and full duplex (FD) user relaying cooperative non orthogonal multiple access (NOMA) system, where a HD/FD user relaying node shares the information to far users from base station (BS). The system works under residual self-interference (RSI) due to imperfect self-interference cancellation. An advanced successive interference cancellation (ASIC) scheme is introduced in the system as an alternative of successive interference cancellation (SIC) technique. The implementation of ASIC scheme in the proposed system is done by mapping the received signal into number of subgroups. Then, the conventional SIC technique is applied to each of these subgroups for decoding information signals. The performance analysis of the proposed system is comprehensively conducted through the closed form expressions, which are derived in terms of outage probability, system throughput, achievable sum rate and energy efficiency. The effectiveness and correctness of the proposed system is verified by analytical results, which clearly boost the outage performance and system throughput than traditional system in moderate to high SNR region. The robustness of the proposed system is also provided with high achievable sum rate and energy efficiency than traditional system under RSI. [ABSTRACT FROM AUTHOR]

The fifth generation of broadband wireless telecommunications will increase the speeds of upload and download with decreasing the access network latency and enable bandwidth in excess of 100s of Megabits per second (Mb/s) with latency of less than 1 millisecond (ms), as well as provide access network to billions of subscribers. In this paper the innovations and challenges of 5G are described such as mm-waves, small cells, Massive MIMO, Beamforming, Full Duplex FD, Non-Orthogonal Multiple Access NOMA, and Mobile Edge Computing MEC. The results show that the millimeter waves development is the dominant innovation of 5G technology, which increases the data traffic 1000 times more data than 4G and offer manufacturing of products with cheaper prices. It is concluded that 5G, represents a big step forward in increasing the flexibility of the network infrastructure, and improve scalability and service. Also 5G is not limited to telecommunication services but it represents the Beyond technology in research, automotive, energy, e-business, e-government, vertical industry, security, e-Health, improving human being's life. 5G will be the future benchmark of smart city. [ABSTRACT FROM AUTHOR]

We consider a full duplex (FD) massive multiple-input multiple-output (mMIMO) cell-free (CF) system, where a large number of multi-antenna FD access points (APs) jointly serve multiple FD user equipments (UEs). The APs transmit precoded downlink pilots for the UEs to estimate the effective downlink channel. For this system, we derive closed-form uplink and downlink spectral efficiency (SE) expressions by considering i) radio-frequency (RF) impairments at the APs and UEs; ii) dynamic resolution analog-to-digital converter/digital-to-analog converter (ADC/DAC) architecture at the APs and low-resolution ADC/DACs at the UEs; and iii) spatially-correlated Rician channels. We then maximize the non-convex global energy efficiency metric by using the block minorization-maximization technique, which decomposes the main optimization into multiple convex surrogate sub-problems. We analytically show that the SE gain obtained with downlink training is limited for practical CF systems with RF and ADC/DAC impairments, Rician channel and pilot contamination. We also extensively investigate the impact of FD interferences on the downlink training gain. [ABSTRACT FROM AUTHOR]

In this paper, we propose a wideband Full Duplex (FD) Multiple-Input Multiple-Output (MIMO) communication system comprising of an FD MIMO node simultaneously communicating with two multi-antenna UpLink (UL) and DownLink (DL) nodes utilizing the same time and frequency resources. To suppress the strong Self-Interference (SI) signal due to simultaneous transmission and reception in FD MIMO systems, we propose a joint design of Analog and Digital (A/D) cancellation as well as transmit and receive beamforming capitalizing on baseband Orthogonal Frequency-Division Multiplexing (OFDM) signal modeling. Considering practical transmitter impairments, we present a multi-tap wideband analog canceller architecture whose number of taps does not scale with the number of transceiver antennas and multipath SI components. We also propose a novel adaptive digital cancellation based on truncated singular value decomposition that reduces the residual SI signal estimation parameters. To maximize the FD sum rate, a joint optimization framework is presented for A/D cancellation and digital beamforming. Finally, our extensive waveform simulation results demonstrate that the proposed wideband FD MIMO design exhibits higher SI cancellation capability with reduced complexity compared to existing cancellation techniques, resulting in improved achievable rate performance. [ABSTRACT FROM AUTHOR]