In hybrid beamforming design using the conventional gradient projection(GP)algorithm,it is common to use a fixed step size,which results in a slow convergence rate and unsatisfactory achievable rate performance.This p...In hybrid beamforming design using the conventional gradient projection(GP)algorithm,it is common to use a fixed step size,which results in a slow convergence rate and unsatisfactory achievable rate performance.This paper employs a deep unfolding algorithm within a small fixed number of iterations to tackle the hybrid beamforming optimization problem.The optimal step size is obtained by combining the conventional GP algorithm with the deep learning technique,and every step in deep learning is explainable.Simulation results show that the proposed deep unfolding algorithm demonstrates a lower computational time and superior achievable rate performance than the conventional GP algorithm.展开更多
The complexities of hardware and signal processing make it especially challenging to develop self-interference cancellation(SIC)techniques for full-duplex(FD)massive multiple-input-multiple-output(MIMO)systems.This pa...The complexities of hardware and signal processing make it especially challenging to develop self-interference cancellation(SIC)techniques for full-duplex(FD)massive multiple-input-multiple-output(MIMO)systems.This paper examines an FD massive MIMO system featuring multi-stream transmission.Specifically,it adopts an architecture where a single transmit or receive radio frequency(RF)channel is connected to three antennas in the same polarization direction,effectively reducing the number of transmit and receive RF channels by half.The SoftNull algorithm serves as the primary method for SI suppression,leveraging digital precoding during transmission.Additionally,this study outlines a design strategy to enhance SIC in the proposed system.Simulation results highlight the efficacy of the SoftNull algorithm,which achieves a remarkable total SIC of up to 64 dB.Furthermore,combined with measures such as antenna isolation and increased trans⁃ceiver array spacing,the resulting sum rate can be twice that of a half-duplex system.展开更多
The reconfigurable intelligent surfaces(RIS)can reconfigure the wireless channel environment by manipulating the propagation of incident electromagnetic waves.Specifically,we consider using multi-RIS to improve the sy...The reconfigurable intelligent surfaces(RIS)can reconfigure the wireless channel environment by manipulating the propagation of incident electromagnetic waves.Specifically,we consider using multi-RIS to improve the system throughput of limited feedback multiple input single output(MISO)system in an energy efficiency manner.The critical challenge lies in the joint design of channel acquisition and beamforming which are usually based on codebook with limited precision.To solve this,we propose a semi-definite relaxation(SDR)based beamforming design scheme while considering the effect of cascaded channel acquisition.First,a channel quantization scheme is proposed by exploiting the channel sparsity in double-RIS aided MISO system.Second,an optimization problem of maximizing the system throughput is established to derive the channel quantization vector which also serves as the beamforming vector,with the consideration of the constraints of transmission power,RISs phase-shift.Third,a SDR based iterative optimization algorithm is proposed to solve the problem with low complexity.Finally,simulation results show that our proposed algorithm can improve the system throughput efficiently.展开更多
PurposeThe purpose of the study was to investigate the effect of bimodal beamforming on speech recognition and comfort for cochlear implant (CI) users with the bimodal hearing solution made up by linking a hearing aid...PurposeThe purpose of the study was to investigate the effect of bimodal beamforming on speech recognition and comfort for cochlear implant (CI) users with the bimodal hearing solution made up by linking a hearing aid to the CI sound processor.Methods19 subjects participated in this study. Speech tests were conducted in quiet and in noisy environments, with the target speech presented from 0° and the noise signal from 45°. Speech recognition thresholds (SRTs) were compared among the previously used bimodal hearing configuration (baseline, any CI sound processor plus any hearing aid), the Naída Bimodal Hearing Solution with omnidirectional microphone, and with directional microphone (so called StereoZoom) switched on. In addition, the study participants provided subjective feedback on their hearing impressions.ResultsThe SRT results showed no significant difference among the three hearing conditions in the quiet environment. No significant improvement was reported when using Naída bimodal system with omnidirectional microphone in noise compared to the baseline (p=0.27). When applying StereoZoom, SRT in noise showed significant improvements compared to omnidirectional settings (p<0.05). Subjective feedback showed that 13 participants were satisfied with Naída Bimodal Hearing Solution, and wanted to continue using it after the trial.ConclusionThe Naída Bimodal Hearing Solution with the same pre-processing algorithm can provide satisfying hearing performance. Beamforming technology can further improve speech perception in noisy environments.展开更多
In this paper,the application of Non-Orthogonal Multiple Access(NOMA)is investigated in a multiple-input single-output network consisting of multiple legitimate users and a potential eavesdropper.To support secure tra...In this paper,the application of Non-Orthogonal Multiple Access(NOMA)is investigated in a multiple-input single-output network consisting of multiple legitimate users and a potential eavesdropper.To support secure transmissions from legitimate users,two NOMA Secrecy Sum Rate Transmit Beam Forming(NOMA-SSR-TBF)schemes are proposed to maximise the SSR of a Base Station(BS)with sufficient and insufficient transmit power.For BS with sufficient transmit power,an artificial jamming beamforming design scheme is proposed to disrupt the potential eavesdropping without impacting the legitimate transmissions.In addition,for BS with insufficient transmit power,a modified successive interference cancellation decoding sequence is used to reduce the impact of artificial jamming on legitimate transmissions.More specifically,iterative algorithm for the successive convex approximation are provided to jointly optimise the vectors of transmit beamforming and artificial jamming.Experimental results demonstrate that the proposed NOMA-SSR-TBF schemes outperforms the existing works,such as the maximized artificial jamming power scheme,the maximized artificial jamming power scheme with artificial jamming beamforming design and maximized secrecy sum rate scheme without artificial jamming beamforming design.展开更多
Unmanned aerial vehicles(UAVs)are expected to be extensively applied in military and commercial fields,but the issues of information security and energy restrictions hinder such applications.To cope with these issues,...Unmanned aerial vehicles(UAVs)are expected to be extensively applied in military and commercial fields,but the issues of information security and energy restrictions hinder such applications.To cope with these issues,joint beamforming and cooperative jamming are promising physicallayer technologies,which are advantageous in improving data rate,energy efficiency(EE),and information security.In this paper,the information security and EE in multi-antenna UAV communications are jointly considered by formulating an optimization problem of secrecy EE maximization subject to secrecy rate and power constraints.The resulting optimization problem focuses on designing the transmit covariance matrices of confidential messages and artificial interference,and is solved in an iterative manner based on the optimization methods of fractional programming and successive convex approximation(SCA).Numerical simulation results demonstrate that the proposed algorithm achieves a significant gain in secrecy EE while satisfying the requirements of secrecy rate and maximum power.展开更多
Using the existing positioning technology can easily obtain high-precision positioning information,which can save resources and reduce complexity when used in the communication field.In this paper,we propose a locatio...Using the existing positioning technology can easily obtain high-precision positioning information,which can save resources and reduce complexity when used in the communication field.In this paper,we propose a location-based user scheduling and beamforming scheme for the downlink of a massive multi-user input-output system.Specifically,we combine an analog outer beamformer with a digital inner beamformer.An outer beamformer can be selected from a codebook formed by antenna steering vectors,and then a reduced-complexity inner beamformer based on iterative orthogonal matrices and right triangular matrices(QR)decomposition is applied to cancel interuser interference.Then,we propose a low-complexity user selection algorithm using location information in this paper.We first derive the geometric angle between channel matrices,which represent the correlation between users.Furthermore,we derive the asymptotic signal to interference-plus-noise ratio(SINR)of the system in the context of two-stage beamforming using random matrix theory(RMT),taking into account inter-channel correlations and energies.Simulation results show that the algorithm can achieve higher system and speed while reducing computational complexity.展开更多
With the widespread application of com-munication technology in the non-terrestrial network(NTN),the issue of the insecure communication due to the inherent openness of the NTN is increasingly being recognized.Consequ...With the widespread application of com-munication technology in the non-terrestrial network(NTN),the issue of the insecure communication due to the inherent openness of the NTN is increasingly being recognized.Consequently,safeguarding com-munication information in the NTN has emerged as a critical challenge.To address this issue,we pro-pose a beamforming and horizontal trajectory joint op-timization method for unmanned aerial vehicle(UAV)covert communications in the NTN.First,we formu-late an optimization problem that considers constraints such as the transmitting power and the distance.More-over,we employ the integrated communication and jamming(ICAJ)signal as Alice’s transmitting signal,further protecting the content of communication in-formation.Next,we construct two subproblems,and we propose an alternate optimization(AO)algorithm based on quadratic transform and penalty term method to solve the proposed two subproblems.Simulation re-sults demonstrate that the proposed method is effective and has better performance than benchmarks.展开更多
Reconfigurable intelligent surface(RIS)is a promising candidate technology of the upcoming Sixth Generation(6G)communication system for its ability to provide unprecedented spectral and energy efficiency increment thr...Reconfigurable intelligent surface(RIS)is a promising candidate technology of the upcoming Sixth Generation(6G)communication system for its ability to provide unprecedented spectral and energy efficiency increment through passive beamforming.However,it is challenging to obtain instantaneous channel state information(I-CSI)for RIS,which obliges us to use statistical channel state information(S-CSI)to achieve passive beamforming.In this paper,RIS-aided multiple-input single-output(MISO)multi-user downlink communication system with correlated channels is investigated.Then,we formulate the problem of joint beamforming design at the AP and RIS to maximize the sum ergodic spectral efficiency(ESE)of all users to improve the network capacity.Since it is too hard to compute sum ESE,an ESE approximation is adopted to reformulate the problem into a more tractable form.Then,we present two joint beamforming algorithms,namely the singular value decomposition-gradient descent(SVD-GD)algorithm and the fractional programming-gradient descent(FP-GD)algorithm.Simulation results show the effectiveness of our proposed algorithms and validate that 2-bits quantizer is enough for RIS phase shifts implementation.展开更多
This paper proposes the Unmanned Aerial Vehicle(UAV)-assisted Full-Duplex(FD)Integrated Sensing And Communication(ISAC)system.In this system,the UAV integrates sensing and communication functions,capable of receiving ...This paper proposes the Unmanned Aerial Vehicle(UAV)-assisted Full-Duplex(FD)Integrated Sensing And Communication(ISAC)system.In this system,the UAV integrates sensing and communication functions,capable of receiving transmission signals from Uplink(UL)users and echo signal from target,while communicating with Downlink(DL)users and simultaneously detecting target.With the objective of maximizing the Average Sum Rate(ASR)for both UL and DL users,a composite non-convex optimization problem is established,which is decomposed into sub-problems of communication scheduling optimization,transceiver beamforming design,and UAV trajectory optimization.An alternating iterative algorithm is proposed,employing relaxation optimization,extremum traversal search,augmented weighted minimum mean square error,and successive convex approximation methods to solve the aforementioned sub-problems.Simulation results demonstrate that,compared to the traditional UAV-assisted Half-Duplex(HD)ISAC scheme,the proposed FD ISAC scheme effectively improves the ASR.展开更多
This paper aims to enhance the array Beamforming(BF) robustness by tackling issues related to BF weight state estimation encountered in Constant Modulus Blind Beamforming(CMBB). To achieve this, we introduce a novel a...This paper aims to enhance the array Beamforming(BF) robustness by tackling issues related to BF weight state estimation encountered in Constant Modulus Blind Beamforming(CMBB). To achieve this, we introduce a novel approach that incorporates an L1-regularizer term in BF weight state estimation. We start by explaining the CMBB formation mechanism under conditions where there is a mismatch in the far-field signal model. Subsequently, we reformulate the BF weight state estimation challenge using a method known as variable-splitting, turning it into a noise minimization problem. This problem combines both linear and nonlinear quadratic terms with an L1-regularizer that promotes the sparsity. The optimization strategy is based on a variable-splitting method, implemented using the Alternating Direction Method of Multipliers(ADMM). Furthermore, a variable-splitting framework is developed to enhance BF weight state estimation, employing a Kalman Smoother(KS) optimization algorithm. The approach integrates the Rauch-TungStriebel smoother to perform posterior-smoothing state estimation by leveraging prior data. We provide proof of convergence for both linear and nonlinear CMBB state estimation technology using the variable-splitting KS and the iterated extended Kalman smoother. Simulations corroborate our theoretical analysis, showing that the proposed method achieves robust stability and effective convergence, even when faced with signal model mismatches.展开更多
基金STU Scientific Research Foundation for Talents under Grants NTF21048。
文摘In hybrid beamforming design using the conventional gradient projection(GP)algorithm,it is common to use a fixed step size,which results in a slow convergence rate and unsatisfactory achievable rate performance.This paper employs a deep unfolding algorithm within a small fixed number of iterations to tackle the hybrid beamforming optimization problem.The optimal step size is obtained by combining the conventional GP algorithm with the deep learning technique,and every step in deep learning is explainable.Simulation results show that the proposed deep unfolding algorithm demonstrates a lower computational time and superior achievable rate performance than the conventional GP algorithm.
文摘The complexities of hardware and signal processing make it especially challenging to develop self-interference cancellation(SIC)techniques for full-duplex(FD)massive multiple-input-multiple-output(MIMO)systems.This paper examines an FD massive MIMO system featuring multi-stream transmission.Specifically,it adopts an architecture where a single transmit or receive radio frequency(RF)channel is connected to three antennas in the same polarization direction,effectively reducing the number of transmit and receive RF channels by half.The SoftNull algorithm serves as the primary method for SI suppression,leveraging digital precoding during transmission.Additionally,this study outlines a design strategy to enhance SIC in the proposed system.Simulation results highlight the efficacy of the SoftNull algorithm,which achieves a remarkable total SIC of up to 64 dB.Furthermore,combined with measures such as antenna isolation and increased trans⁃ceiver array spacing,the resulting sum rate can be twice that of a half-duplex system.
基金supported the Innovation Talents Promotion Program of Shaanxi Province under Grant No.2021TD-08。
文摘The reconfigurable intelligent surfaces(RIS)can reconfigure the wireless channel environment by manipulating the propagation of incident electromagnetic waves.Specifically,we consider using multi-RIS to improve the system throughput of limited feedback multiple input single output(MISO)system in an energy efficiency manner.The critical challenge lies in the joint design of channel acquisition and beamforming which are usually based on codebook with limited precision.To solve this,we propose a semi-definite relaxation(SDR)based beamforming design scheme while considering the effect of cascaded channel acquisition.First,a channel quantization scheme is proposed by exploiting the channel sparsity in double-RIS aided MISO system.Second,an optimization problem of maximizing the system throughput is established to derive the channel quantization vector which also serves as the beamforming vector,with the consideration of the constraints of transmission power,RISs phase-shift.Third,a SDR based iterative optimization algorithm is proposed to solve the problem with low complexity.Finally,simulation results show that our proposed algorithm can improve the system throughput efficiently.
基金supported by grants from Capital’s Funds for Health Improvement and Research(No.2022-1-2023)the National Natural Science Foundation of China(No.82371148)Open project National Clinical Research Center for Otolaryngologic Diseases(202200010).
文摘PurposeThe purpose of the study was to investigate the effect of bimodal beamforming on speech recognition and comfort for cochlear implant (CI) users with the bimodal hearing solution made up by linking a hearing aid to the CI sound processor.Methods19 subjects participated in this study. Speech tests were conducted in quiet and in noisy environments, with the target speech presented from 0° and the noise signal from 45°. Speech recognition thresholds (SRTs) were compared among the previously used bimodal hearing configuration (baseline, any CI sound processor plus any hearing aid), the Naída Bimodal Hearing Solution with omnidirectional microphone, and with directional microphone (so called StereoZoom) switched on. In addition, the study participants provided subjective feedback on their hearing impressions.ResultsThe SRT results showed no significant difference among the three hearing conditions in the quiet environment. No significant improvement was reported when using Naída bimodal system with omnidirectional microphone in noise compared to the baseline (p=0.27). When applying StereoZoom, SRT in noise showed significant improvements compared to omnidirectional settings (p<0.05). Subjective feedback showed that 13 participants were satisfied with Naída Bimodal Hearing Solution, and wanted to continue using it after the trial.ConclusionThe Naída Bimodal Hearing Solution with the same pre-processing algorithm can provide satisfying hearing performance. Beamforming technology can further improve speech perception in noisy environments.
基金supported in part by the Natural Science Foundation of Fujian Province under Grant 2022J01169the Local Science and Technology Development of Fujian Province under Grant 2021L3010+3 种基金the Key Project of Science and Technology Innovation of Fujian Province under Grant 2021G02006the National Natural Science Foundation of China under Grants 61971360 and 62271420the National Natural Science Foundation of China under Grant 62071247the Urban Carbon Neutral Science and Technology Innovation Fund Project of Beijing University of Technology ($040000514122607$)。
文摘In this paper,the application of Non-Orthogonal Multiple Access(NOMA)is investigated in a multiple-input single-output network consisting of multiple legitimate users and a potential eavesdropper.To support secure transmissions from legitimate users,two NOMA Secrecy Sum Rate Transmit Beam Forming(NOMA-SSR-TBF)schemes are proposed to maximise the SSR of a Base Station(BS)with sufficient and insufficient transmit power.For BS with sufficient transmit power,an artificial jamming beamforming design scheme is proposed to disrupt the potential eavesdropping without impacting the legitimate transmissions.In addition,for BS with insufficient transmit power,a modified successive interference cancellation decoding sequence is used to reduce the impact of artificial jamming on legitimate transmissions.More specifically,iterative algorithm for the successive convex approximation are provided to jointly optimise the vectors of transmit beamforming and artificial jamming.Experimental results demonstrate that the proposed NOMA-SSR-TBF schemes outperforms the existing works,such as the maximized artificial jamming power scheme,the maximized artificial jamming power scheme with artificial jamming beamforming design and maximized secrecy sum rate scheme without artificial jamming beamforming design.
基金Supported by the National Natural Science Foundation of China(No.61871401).
文摘Unmanned aerial vehicles(UAVs)are expected to be extensively applied in military and commercial fields,but the issues of information security and energy restrictions hinder such applications.To cope with these issues,joint beamforming and cooperative jamming are promising physicallayer technologies,which are advantageous in improving data rate,energy efficiency(EE),and information security.In this paper,the information security and EE in multi-antenna UAV communications are jointly considered by formulating an optimization problem of secrecy EE maximization subject to secrecy rate and power constraints.The resulting optimization problem focuses on designing the transmit covariance matrices of confidential messages and artificial interference,and is solved in an iterative manner based on the optimization methods of fractional programming and successive convex approximation(SCA).Numerical simulation results demonstrate that the proposed algorithm achieves a significant gain in secrecy EE while satisfying the requirements of secrecy rate and maximum power.
基金supported by the National Natural Science Foundation of China(61901341).
文摘Using the existing positioning technology can easily obtain high-precision positioning information,which can save resources and reduce complexity when used in the communication field.In this paper,we propose a location-based user scheduling and beamforming scheme for the downlink of a massive multi-user input-output system.Specifically,we combine an analog outer beamformer with a digital inner beamformer.An outer beamformer can be selected from a codebook formed by antenna steering vectors,and then a reduced-complexity inner beamformer based on iterative orthogonal matrices and right triangular matrices(QR)decomposition is applied to cancel interuser interference.Then,we propose a low-complexity user selection algorithm using location information in this paper.We first derive the geometric angle between channel matrices,which represent the correlation between users.Furthermore,we derive the asymptotic signal to interference-plus-noise ratio(SINR)of the system in the context of two-stage beamforming using random matrix theory(RMT),taking into account inter-channel correlations and energies.Simulation results show that the algorithm can achieve higher system and speed while reducing computational complexity.
基金supported in part by the National Natural Science Foundation of China under Grant U2441250 and 62231027in part by Natural Science Basic Research Programof Shaanxi under Grant 2024JC-JCQN-63+2 种基金in part by InnovationCapability Support Program of Shaanxi under Grant2024RS-CXTD-01in part by New Technology Research University Cooperation Project under Grant SKX242010031in part by the FundamentalResearch Funds for the Central Universities and theInnovation Fund of Xidian University under GrantYJSJ25007.
文摘With the widespread application of com-munication technology in the non-terrestrial network(NTN),the issue of the insecure communication due to the inherent openness of the NTN is increasingly being recognized.Consequently,safeguarding com-munication information in the NTN has emerged as a critical challenge.To address this issue,we pro-pose a beamforming and horizontal trajectory joint op-timization method for unmanned aerial vehicle(UAV)covert communications in the NTN.First,we formu-late an optimization problem that considers constraints such as the transmitting power and the distance.More-over,we employ the integrated communication and jamming(ICAJ)signal as Alice’s transmitting signal,further protecting the content of communication in-formation.Next,we construct two subproblems,and we propose an alternate optimization(AO)algorithm based on quadratic transform and penalty term method to solve the proposed two subproblems.Simulation re-sults demonstrate that the proposed method is effective and has better performance than benchmarks.
基金partially supported by the National Key Research and Development Project under Grant 2020YFB1806805Science and Technology on Communication Networks Laboratorysupported by China Scholarship Council.
文摘Reconfigurable intelligent surface(RIS)is a promising candidate technology of the upcoming Sixth Generation(6G)communication system for its ability to provide unprecedented spectral and energy efficiency increment through passive beamforming.However,it is challenging to obtain instantaneous channel state information(I-CSI)for RIS,which obliges us to use statistical channel state information(S-CSI)to achieve passive beamforming.In this paper,RIS-aided multiple-input single-output(MISO)multi-user downlink communication system with correlated channels is investigated.Then,we formulate the problem of joint beamforming design at the AP and RIS to maximize the sum ergodic spectral efficiency(ESE)of all users to improve the network capacity.Since it is too hard to compute sum ESE,an ESE approximation is adopted to reformulate the problem into a more tractable form.Then,we present two joint beamforming algorithms,namely the singular value decomposition-gradient descent(SVD-GD)algorithm and the fractional programming-gradient descent(FP-GD)algorithm.Simulation results show the effectiveness of our proposed algorithms and validate that 2-bits quantizer is enough for RIS phase shifts implementation.
基金supported in part by Sub Project of National Key Research and Development Plan in 2020.NO.2020YFC1511704Beijing Information Science&Technology University.NO.2020KYNH212,NO.2021CGZH302+1 种基金Beijing Science and Technology Project(Grant No.Z211100004421009)in part by the National Natural Science Foundation of China(Grant No.62301058).
文摘This paper proposes the Unmanned Aerial Vehicle(UAV)-assisted Full-Duplex(FD)Integrated Sensing And Communication(ISAC)system.In this system,the UAV integrates sensing and communication functions,capable of receiving transmission signals from Uplink(UL)users and echo signal from target,while communicating with Downlink(DL)users and simultaneously detecting target.With the objective of maximizing the Average Sum Rate(ASR)for both UL and DL users,a composite non-convex optimization problem is established,which is decomposed into sub-problems of communication scheduling optimization,transceiver beamforming design,and UAV trajectory optimization.An alternating iterative algorithm is proposed,employing relaxation optimization,extremum traversal search,augmented weighted minimum mean square error,and successive convex approximation methods to solve the aforementioned sub-problems.Simulation results demonstrate that,compared to the traditional UAV-assisted Half-Duplex(HD)ISAC scheme,the proposed FD ISAC scheme effectively improves the ASR.
基金supported in Natural Science Foundation of Shandong Province,China(ZR2013FM018)。
文摘This paper aims to enhance the array Beamforming(BF) robustness by tackling issues related to BF weight state estimation encountered in Constant Modulus Blind Beamforming(CMBB). To achieve this, we introduce a novel approach that incorporates an L1-regularizer term in BF weight state estimation. We start by explaining the CMBB formation mechanism under conditions where there is a mismatch in the far-field signal model. Subsequently, we reformulate the BF weight state estimation challenge using a method known as variable-splitting, turning it into a noise minimization problem. This problem combines both linear and nonlinear quadratic terms with an L1-regularizer that promotes the sparsity. The optimization strategy is based on a variable-splitting method, implemented using the Alternating Direction Method of Multipliers(ADMM). Furthermore, a variable-splitting framework is developed to enhance BF weight state estimation, employing a Kalman Smoother(KS) optimization algorithm. The approach integrates the Rauch-TungStriebel smoother to perform posterior-smoothing state estimation by leveraging prior data. We provide proof of convergence for both linear and nonlinear CMBB state estimation technology using the variable-splitting KS and the iterated extended Kalman smoother. Simulations corroborate our theoretical analysis, showing that the proposed method achieves robust stability and effective convergence, even when faced with signal model mismatches.
