Full-duplex Mode Research Articles

SWIPT-Based Energy Scheduling for Solar-Powered WSN in Full-Duplex Mode

Solar harvesting, as the most mature environmental energy harvesting technology, can provide a convenient, low-carbon, and off-grid solution for energy-constrained WSN in remote environmental monitoring. However, the stochastic and intermittent nature of solar energy seriously affects network energy efficiency. In this paper, we jointly consider solar harvest deployment and scheduling for clustered WSN collaborating with SWIPT, where the solar-powered cluster (SC) coordinates SWIPT to periodically broadcast energy to a set of wireless charging nodes in full-duplex mode, each member node exhausts the recharged energy for data sensing and forwarding. To maximize network energy efficiency, we formulate a Solar harvesting collaborative SWIPT Energy Scheduling(SS-CoES) optimization problem, which jointly optimizes the deployment of SCs, the energy broadcast power with time allocation, and data sensing size under the constraint of the self-sustaining demand for network energy. Given the combinational nature of the energy deployment with its strong coupling with energy scheduling, we propose a multi-layer iteration decoupling optimization algorithm based on the Dinkelbach method, which decouples the problem into three subproblems and proposes the Hybrid discrete Firefly algorithm, Lagrangian dual subgradient algorithm, and bisection search method to obtain near-optimal feasible solutions. Simulation results show that the proposed SS-CoES can effectively maximize network energy efficiency and eliminate the dependence on the grid and move chargers, achieving rechargeable wireless sensor networks (RWSN) energy self-sustainability in remote areas.

Performance analysis of IRS‐aided cooperative NOMA‐MEC system

In this paper, an intelligent reflecting surface (IRS) assisted cooperative non-orthogonal multiple access and mobile edge computing (NOMA-MEC) system is proposed, where a base station sends signals to users through the virtue of the IRS. When the direct links between the base station and the user are blocked, the offloading tasks will be refracted to the near-end user through the IRS and forwarded to the remote user, where the near-end user is equipped with an MEC server working at full duplex or half duplex mode. To evaluate the potential performance of IRS aided cooperative NOMA-MEC, new closed-form expressions of the offloading outage probability is deduced for a pair of users. The asymptotic expressions of offloading outage probability are provided in the high signal-to-noise ratio regime. Simulation results are presented to substantiate the analyses and demonstrate that: (i) The offloading outage behaviors of IRS-aided cooperative NOMA-MEC systems are superior to that of NOMA-MEC without IRS and IRS-aided OMA-MEC; (ii) As the value of parameter Q increases, the IRS-aided NOMA-MEC system is capable of achieving the enhanced offloading outage performance; (iii) By comparing with NOMA-MEC without IRS and IRS-aided OMA-MEC, the energy efficiency and system throughput of IRS-aided NOMA-MEC has obvious advantages in delay-limited transmission mode.

Energy Efficiency of Full- and Half-Duplex Decode-and-Forward Relay Channels

This article studies the energy efficiency (EE) of a three-node decode-and-forward (DF) relay channel, where the relay operates in full-duplex (FD) or half-duplex (HD) mode. In particular, for the FD mode, both the residual self-interference (RSI) and the extra circuit power consumption introduced by the self-interference cancellation (SIC) at the relay node are considered and modeled as linear functions over the relay transmission power. Under this setup, the EE maximization problems for the considered FD and HD modes subject to the total transmission power and spectral efficiency (SE) constraints are formulated as max–min problems, whose optimal power allocation is computed by fractional programming. Next, the EEs for the FD, HD, and direct transmission (DT) modes are compared under different channel conditions, and a hybrid mode selection scheme, i.e., selecting the one with the maximum EE among the above three modes, is proposed. Besides, we also prove that both the EE and the SE monotonically increase with the total transmission power under a given condition. Finally, numerical results show that the maximum EE of the FD relaying exceeds those of the HD and DT ones when the required SE is relatively high. Furthermore, the proposed hybrid mode selection scheme can provide up to 192.4% higher EE compared with the DT mode.

Throughput Enhancement in FD- and SWIPT-Enabled IoT Networks Over Nonidentical Rayleigh Fading Channels

Simultaneous wireless information and power transfer (SWIPT) and full-duplex (FD) communications have emerged as prominent technologies in overcoming the limited energy resources in Internet of Things (IoT) networks and improving their spectral efficiency (SE). This article investigates the outage and throughput performance for a decode-and-forward (DF) relay SWIPT system, which consists of one source, multiple relays, and one destination. The relay nodes in this system can harvest energy from the source’s signal and operate in the FD mode. A suboptimal, low-complexity, yet efficient relay selection scheme is also proposed. Specifically, a single relay is selected to convey information from a source to a destination so that it achieves the best channel from the source to the relays. An analysis of outage probability (OP) and throughput performed on two relaying strategies, termed static power splitting-based relaying (SPSR) and optimal dynamic power splitting-based relaying (ODPSR), is presented. Notably, we considered independent and nonidentically distributed (i.n.i.d.) Rayleigh fading channels, which pose new challenges in obtaining analytical expressions. In this context, we derived exact closed-form expressions of the OP and throughput of both SPSR and ODPSR schemes. We also obtained the optimal power splitting ratio of ODPSR for maximizing the achievable capacity at the destination. Finally, we present extensive numerical and simulation results to confirm our analytical findings. Both simulation and analytical results show the superiority of ODPSR over SPSR.

On the Secrecy Outage Performance of Cooperative NOMA-Assisted Hybrid Satellite-Terrestrial Networks

This paper investigates the secrecy outage performance of a downlink cooperative nonorthogonal multiple access- (NOMA-) assisted hybrid satellite-terrestrial network, where a satellite source communicates with two terrestrial users based on NOMA, in the presence of a terrestrial eavesdropper. We assume that there is no direct link between the satellite source and the far terrestrial user, and the near terrestrial user acts as a relay to forward the information to the far terrestrial user. The near user is assumed to support both half-duplex mode and the full-duplex mode for information relaying. We derive the closed-form exact expressions for the secrecy outage probability (SOP) of the near user, as well as the closed-form approximate expressions for the SOP of the far user based on the Gaussian-Chebyshev quadrature. Theoretical results are validated by conducting simulations. The impacts of various system parameters on the performance comparison between the half-duplex mode and full-duplex mode are investigated. Particularly, the full-duplex mode is shown to outperform the half-duplex mode when the received signal-to-noise ratio (SNR) at the near user is low or the residual self-interference is low.

Virtual full-duplex buffer-aided relay selection schemes for secure cooperative wireless networks

This paper considers secure communication in buffer-aided cooperative wireless networks in the presence of one eavesdropper, which can intercept the data transmission from both the source and relay nodes. It is assumed that the relays employ the randomize-and-forward (RF) strategy such that the eavesdropper can only decode the signals received in the two hops independently. Two cooperative secure transmission schemes, i.e., hybrid imitating full-duplex max-max-ratio relay selection (HyIFD) scheme and threshold-based link selection (TBLS) scheme are proposed for adaptive- and fixed-rate transmissions aiming at improving the secrecy throughput and secrecy outage probability, respectively. For adaptive-rate transmissions (ART), the proposed scheme switches among three sub-strategies according to different conditions such as the number of relays and transmit power. Different relays are chosen for reception and transmission according to the ratio of the legitimate channels to the eavesdropper channels to imitate the full-duplex transmission mode. For fixed-rate transmissions (FRT), a hybrid HD/FD transmission mode is designed to increase the transmission probabilities of two hops under the transmission quality constraint. Two parameters are introduced and optimized to minimize the secrecy outage probability. A sub-optimal TBLS (SO-TBLS) scheme is also given. Theoretical analysis of the secrecy throughput and the secrecy outage probability are provided and the closed-form expressions are derived, and verified by numerical results. It is shown that the proposed schemes outperform benchmark schemes in terms of secrecy throughput and secrecy outage probability.

UGV-Assisted Wireless Powered Backscatter Communications for Large-Scale IoT Networks

Wireless powered backscatter communications (WPBC) is capable of implementing ultra-low-power communication, thus promising in the Internet of Things (IoT) networks. In practice, however, it is challenging to apply WPBC in large-scale IoT networks because of its short communication range. To address this challenge, this paper exploits an unmanned ground vehicle (UGV) to assist WPBC in large-scale IoT networks. In particular, we investigate the joint design of network planning and dynamic resource allocation of the access point (AP), tag reader, and UGV to minimize the total energy consumption. Also, the AP can operate in either half-duplex (HD) or full-duplex (FD) multiplexing mode. Under HD mode, the optimal cell radius is derived and the optimal power allocation and transmit/receive beamforming are obtained in closed form. Under FD mode, the optimal resource allocation, as well as two suboptimal ones with low computational complexity, is developed. Simulation results disclose that dynamic power allocation at the tag reader rather than at the AP dominates the network energy efficiency while the AP operating in FD mode outperforms that in HD mode concerning energy efficiency.

Covert Rate Optimization of Millimeter Wave Full-Duplex Communications

In this paper, we consider the problem of full-duplex covert millimeter wave (mmWave) communications, where a mmWave transmitter (Alice) sends information signals to its intended receiver (Bob) covertly in the presence of a watchful warden (Willie). For covering the presence of Alice, Bob operates in the full-duplex mode and generates jamming signals with a time-varying power. We investigate the covert rate optimization for both the single data stream case and the multiple data streams case under the constraints of the detection error probability at Willie. Specifically, for the single data stream case, we analytically characterize the minimum detection error probability at Willie and establish a framework for optimizing the analog beamforming, transmit power, and analog jamming jointly. As for the case of multiple data streams, we derive a tractable lower bound of the minimum detection error probability at Willie and formulate a joint optimization of the hybrid precoder and analog jamming design problem for the maximization of the achievable covert rate. Although the joint design problem is nonconvex, we adopt the penalty decomposition technique to handle the effect of the coupling between the analog precoder and digital precoder paving the way for the development of an iterative algorithm to locate its Karush-Kuhn-Tucker (KKT) solution. Finally, we show that our proposed joint design algorithm can be adapted to handle the multi-antenna Willie scenario and simulation results show that our proposed joint design algorithms can achieve significantly better performance as compared with some benchmark schemes.

Dynamic User Clustering and Optimal Power Allocation in UAV-Assisted Full-Duplex Hybrid NOMA System

This paper investigates unmanned aerial vehicles (UAVs)-assisted full-duplex (FD) non-orthogonal multiple access (NOMA) system based cellular network, aiming to improve overall sum-rate throughput of the system through dynamic user clustering, optimal UAV placement and power allocation. Since each UAV operates in FD mode, self-interference (SI), co-channel interference (CCI), inter-UAV interference (IUI) and intra-node interference (INI) dominate the system&#x2019;s performance. Consequently, we propose an unconventional two-stage dynamic user clustering for user nodes (UNs) to reduce the cross-interference in multi-UAV aided FD-NOMA system. Particularly, all UNs are initially clustered into <inline-formula> <tex-math notation="LaTeX">$K$ </tex-math></inline-formula> clusters using k-means clustering in the first stage where each cluster is served by an UAV. Furthermore, each cluster is further divided into sub-clusters and each sub-clusters are operated in FD-NOMA scheme. Finally, to control interferences, a sum-rate throughput maximization problem is formulated for each UAV to jointly optimize uplink and downlink power allocation and UAV placement. The joint optimization problem is non-convex and difficult to solve directly, for which we decoupled the original problem by addressing UAV placement and power allocation separately. We first fix the UAV position and then solve the problem iteratively using successive convex approximation (SCA) method. By utilizing brute-force search algorithm, an optimal UAV placement is later performed which corresponds to maximum possible sum-rate throughput. Simulation results demonstrate that the proposed solution for the considered FD-NOMA system outperforms the conventional schemes.

Resource Configuration for Full-Duplex-Aided Multiple-Access Edge Computation Offloading

Multiple-access edge computation offloading (MECO) systems have been highlighted as a solution for extending the battery life and computation capability of mobile devices. However, in scenarios where information data and computation offloading (CO) data coexist, CO users and information users affect each other. It means that the communication resources for information data transmission are inevitably reduced by the communication resources allocated for CO in the conventional half-duplex (HD) based systems. Hence, improving the spectral efficiency of MECO systems in coexistence scenarios is essential, and we investigate a full-duplex (FD)-aided MECO (FD-MECO) system. A step-wise resource configuration is proposed to improve the performance of computation offloading under the information data rate constraint. The main idea is to improve spectral efficiency by maximizing the opportunity of operating in FD mode. By comparing all the communication phases in FD-MECO systems, the proposed resource configuration maximizes the amount of delivered CO data while guaranteeing the required information data rate. The simulation results show that FD-MECO systems with the proposed resource configuration always outperform HD-MECO systems.

A Novel Hybrid Duplex Scheme for Relay Channel: Joint Optimization of Full-Duplex Duty Cycle and Source Power Allocation

Full-duplex (FD) mode has great potential in improving the spectral efficiency. Mitigating the effect of self-interference becomes one key for performance enhancement of FD system. This work proposes a novel hybrid duplex scheme where the relay receives information for a fraction of time and simultaneously transmits and receives information for the rest, following a duty cycle. First, we formulate the achievable rate maximization of the proposed scheme as a joint FD duty cycle and source power allocation optimization problem. The optimal FD duty cycle, the optimal source power allocation, and the maximal achievable rate are explicitly given for some cases and characterized in detail for other cases. Then, the proposed scheme is applied to two-hop relaying systems. Specifically, the optimal source power allocation is proved to be a water-filling solution over the FD phase and the receives-only phase on the source-relay link. By dividing the system as low-, medium-, and high-source power cases, the optimal FD duty cycle and the maximal achievable rate are obtained in (approximate) closed-form case-by-case, where the source power thresholds among cases are clearly expressed. Numerical results validate that the proposed hybrid duplex scheme outperforms other benchmark schemes and can improve the achievable rate significantly.

Impacts of relay and direct links at destinations in full-duplex non-orthogonal multiple access system

In this study, one of effective methods of multiple access, namely non-orthogonal multiple access (NOMA), is investigated. Such NOMA scheme can be worked with signal processing at downlink side. As such, the base station sends mixed signals of two signals to destinations. A near user could be a relay to forward the signal to the distant user by leveraging benefits of full-duplex mode which allows relay to transmit and receive signals in the same time. For simple analysis, the two-user approach and fixed power allocation factors are implemented. We also derive formulas of the outage probability of two users (near-user and far-user) to indicate fairness and emphasize the role of the near user as a relay. This considered NOMA system adopts transmission with Nakagami-m fading channel. As a further metric, throughput is considered under the impacts of key system parameters. The transmit signal-to-noise ratio (SNR) at the base station make influences the performance of two users significantly as observation indicated in our simulation results. These results are confirmed by matching Monte-Carlo with the theoretical simulations.

Outage performance of CoMP-CNOMA networks with duplex mode selection

This paper investigates the outage performance of a downlink coordinated multipoint cooperative non-orthogonal multiple access (CoMP-CNOMA) network, where two near users cooperatively relay the information to a far user. It is assumed that the near users support both the half-duplex relaying mode and the full-duplex relaying mode. Since the full-duplex mode may be inferior to the half-duplex mode due to the residual self-interference under the full-duplex mode, we propose a duplex mode selection strategy for the near users to dynamically choose the duplex mode for relaying. Under the proposed duplex mode selection strategy, the closed form expressions for the outage probabilities of all the users are derived. The theoretical results match well with the Monte Carlo simulations. It is shown that the proposed duplex mode selection strategy can provide low outage probabilities of all the users simultaneously, while the existing duplex mode selection strategies either achieve higher outage probabilities of all the users or achieve slightly better outage performance of the far user at the sacrifice of much worse outage performance of the near users.

Interference Management with Reflective In-Band Full-Duplex NOMA for Secure 6G Wireless Communication Systems.

The electromagnetic spectrum is used as a medium for modern wireless communication. Most of the spectrum is being utilized by the existing communication system. For technological breakthroughs and fulfilling the demands of better utilization of such natural resources, a novel Reflective In-Band Full-Duplex (R-IBFD) cooperative communication scheme is proposed in this article that involves Full-Duplex (FD) and Non-Orthogonal Multiple Access (NOMA) technologies. The proposed R-IBFD provides efficient use of spectrum with better system parameters including Secrecy Outage Probability (SOP), throughput, data rate and secrecy capacity to fulfil the requirements of a smart city for 6th Generation (6thG or 6G). The proposed system targets the requirement of new algorithms that contribute towards better change and bring the technological revolution in the requirements of 6G. In this article, the proposed R-IBFD mainly contributes towards co-channel interference and security problem. The In-Band Full-Duplex mode devices face higher co-channel interference in between their own transmission and receiving antenna. R-IBFD minimizes the effect of such interference and assists in the security of a required wireless communication system. For a better understanding of the system contribution, the improvement of secrecy capacity and interference with R-IBFD is discussed with the help of SOP derivation, equations and simulation results. A machine learning genetic algorithm is one of the optimization tools which is being used to maximize the secrecy capacity.

Characterization of MmWave Full-Duplex Cloud-Radio Access Network (C-RAN) with RRH Selection for 5G and Beyond

In this paper, a millimeter-wave (mmWave) full-duplex (FD) cloud radio access network (C-RAN) for 5G and beyond systems is studied, where the central unit is equipped with multiple antennas, and the spatially distributed remote radio heads (RRHs) operate in FD mode. In particular, we analyze a relay selection method based on end-to-end signal to interference plus noise ratio (SINR) in the proposed system. Distinguishing features of mmWave communications such as Rician small scale fading, path loss, blockage and directivity are taken into account in both fronthaul (FH) and access links. In order to have a comparison basis, the performance of the RRH selection method is also investigated in half-duplex (HD) mmWave C-RAN. Initially, the expression of the end-to-end SINR in the proposed system is derived, and then the cumulative density function (CDF) of the end-to-end SINR is derived in both FD and HD RRHs. Subsequently, we derive performance expressions such as outage probability, average rate and energy efficiency for the RRH selection method in the proposed system in both HD and FD mmWave C-RAN. Finally, the effectiveness of the RRH selection method and the accuracy of the obtained results are verified via Monte Carlo simulation results, which show that the RRH selection method in the mmWave FD C-RAN improves the performance significantly.

Exploiting FD/HD Cooperative-NOMA in Underlay Cognitive Hybrid Satellite-Terrestrial Networks

This paper investigates the performance of an underlay cognitive hybrid satellite-terrestrial network comprising a primary satellite source with its multiple terrestrial primary receivers and a secondary transmitter with its pre-paired users that are deployed on the ground based on a cooperative non-orthogonal multiple access (C-NOMA) scheme. Herein, the nearby NOMA user works in full-duplex (FD) mode while employing a decode-and-forward relaying strategy for improving the performance of the far-away NOMA user. Importantly, we consider the realistic assumptions of FD-based loop self-interference and NOMA-based imperfect successive interference cancellation (SIC). By exploiting the mutual interference and the pertinent hybrid channels, we analyze the performance of the secondary network in terms of outage probability (OP), ergodic sum rate, and throughput. Further, to perform a more comprehensive analysis, both perfect SIC (pSIC) and imperfect SIC (ipSIC) situations are taken into account for the FD mode and the benchmark half-duplex (HD) mode for comparison purposes. Also, we examine the asymptotic OP behaviour at a high signal-to-noise ratio (SNR) to assess the achievable diversity orders. Our results manifest that FD C-NOMA outperforms HD C-NOMA for the case of ipSIC, whereas for the case of pSIC, HD C-NOMA can outperform FD C-NOMA in the high SNR regime.

Transceiver Design and Power Control for Full-Duplex Ultra-Reliable Low-Latency Communication Systems

Ultra-reliable low-latency communication (URLLC) is one of the most important components in the fifth generation (5G) cellular networks for realizing mission-critical applications. In this paper, we jointly optimize the transceiver design and decoding error probability (DEP) of a full-duplex (FD) URLLC system, where the base station (BS) operates in FD mode, while the uplink (UL) and downlink (DL) users work in half-duplex (HD) mode. Accordingly, an optimization problem is formulated to maximize the achievable total (UL plus DL) rate for an FD URLLC system under finite blocklength, subject to the end-to-end (E2E) reliability constraint from the UL user to each DL user and the total transmission power constraint at the UL user and at the BS. We analyze the problem structure and convexify the problem by approximating the channel dispersion in scenarios of high and mid-to-high signal-to-interference plus noise ratio (SINR) regimes, respectively. Next, efficient iterative algorithms are proposed to find the near-optimal power allocation for the UL user and transceiver weights for the BS. Furthermore, closed-form expressions of the transceiver weights are derived, and the convergence of the proposed algorithms is proved. Simulation examples demonstrate the impact of the code blocklength, number of DL users, transmitter/receiver distortion and DEP threshold on the system performance.

Half-Duplex Mode-Based Secure Key Generation Method for Resource-Constrained IoT Devices

The physical layer secret key generation scheme is a preferred solution designed for resource-constrained Internet of Things (IoT) devices. But it suffers from a severe attack, the signal manipulating attack, which aims at controlling the generated key. The existing solutions either cannot prevent all kinds of signal manipulation attacks or require working in full-duplex mode, which is not suitable for resource-constrained IoT devices. In this article, we introduce a secret key generation scheme with the help of an untrusted relay to address this dilemma. Also, our method can protect the privacy of legitimate users from the untrusted relay. We conclude a general signal manipulation attack model from existing practical signal manipulation attacks and analyze the security strength and privacy preserving ability of our scheme based on this model. Finally, we compare our method with existing signal manipulation attack solutions. The result shows that our method is the best solution for resource-constrained IoT systems.

Analogue vs Digital - a (user) Experience Perspective

Introduction I’d like to speak about “analogue versus digital”. For a lot of people, when you speak about analogue versus digital, they think about sound, the sound of analogue versus the sound of digital. But I argue that it is often related to the experience that we have as we use analogue versus that when we use digital. I’d like to start asking few questions. I’ll show you few options on the board and I need you to choose just one of them. Which one do you belong to? The studio Suppose you have a plan for working in a studio. You have a choice to go to two studios. Do you prefer to go to studio 1 or to studio 2? Plug-ins From the following plugins, imagine that at the end of today, you get one of them for free. I need you to choose the plug-in you want and to think about the time it took you to make a choice. Choose between these plug-ins Choose between these plug-ins 2. Personal background 2001 In 2001, I was a songwriter and a (bad) multi-instrumentalist. I could play a bit of drums, a bit of bass, a bit of keyboard, a bit of guitar, a bit of trumpet and I had nearly ten years of experience in recording and mixing. A kind of luck, I think I was very comfortable with mixing. It was mixing exclusively “In-the-box”, that means using DAW, using computers. It was the beginning of working in full duplex mode, using audio cards for recording and playing sounds at the same time. Then I started a Recording Arts degree at SAE in London. The reason I did was because I simply w

Impact of Self-Energy Recycling and Cooperative Jamming on SWIPT-Based FD Relay Networks With Secrecy Constraints

This paper investigates the secrecy performance of a power splitting-based simultaneous wireless information and power transfer cooperative relay network in the presence of an eavesdropper. The relay is considered to operate in full-duplex (FD) mode to perform both energy harvesting and information decoding simultaneously. To accomplish that, the relay is assumed to employ two rechargeable batteries, which switch between power supplying mode and charging mode at each transmission block. We also assume that the self-interference inherent of the FD mode is not completely suppressed. Therefore, it is assumed that, after some stages of passive and active self-interference cancellation, there is still a residual self-interference (RSI). A portion of this RSI (remaining after passive cancellation) is recycled for energy harvesting. In order to improve the system secrecy performance, it is considered that the relay can split its transmit power to send the information signal and to emit a jamming signal to degrade the eavesdropper&#x2019;s channel. The secrecy performance is evaluated in terms of the secrecy outage probability and the optimal secrecy throughput. Tight-approximate and asymptotic expressions are obtained for the secrecy outage probability, and the particle swarm optimization method is employed for addressing the secrecy throughput optimization problem. From numerical results, we show that the secrecy performance can be increased depending on the self-energy recycling channel condition. Finally, our derived expressions are validated via Monte Carlo simulations.