Adaptive broadband beamforraing is a key issue in array applications. The adaptive broadband beamformer with tapped delay line （TDL） structure for nonuniform linear array （NLA） is designed according to the rule of...Adaptive broadband beamforraing is a key issue in array applications. The adaptive broadband beamformer with tapped delay line （TDL） structure for nonuniform linear array （NLA） is designed according to the rule of minimizing the beamformer＇s output power while keeping the distortionless response （DR） in the direction of desired signal and keeping the constant beamwidth （CB） with the prescribed sidelobe level over the whole operating band. This kind of beamforming problem can be solved with the interior-point method after being converted to the form of standard second order cone programming （SOCP）. The computer simulations are presented which illustrate the effectiveness of our beamformer.展开更多
In performing a gaming task,mental rotation(MR)is one of the important aspects of visuospatial processing.MR involves dorsal-ventral pathways of the brain.Visual objects/models used in computer-games play a crucial ro...In performing a gaming task,mental rotation(MR)is one of the important aspects of visuospatial processing.MR involves dorsal-ventral pathways of the brain.Visual objects/models used in computer-games play a crucial role in gaming experience of the users.The visuospatial characteristics of the objects used in the computer-game influence the engagement of dorsal-ventral visual pathways.The current study investigates how the objects’visuospatial characteristics(i.e.,angular disparity and dimensionality)in an MR-based computer-game influence the cortical activities in dorsalventral visual pathways.Both the factors have two levels,angular disparity:convex angle(CA)vs.reflex angle(RA)and dimensionality:2D vs.3D.Sixty healthy adults,aged,18-29 years(M=21.6)were recruited for the study and randomly assigned to four gaming conditions i.e.,15 participants in each group.The multichannel electroencephalogram(EEG)data were recorded from 60 healthy adults while playing the game.The source reconstruction was done for∼3000 sources inside the brain using the Dynamic Imaging of Coherent Sources(DICS)beamforming method forθ1(4-5.75),θ2(5.75-7.5),α1(7.5-9),α2(9-11),α3(11-13),β1(13-17.25),β2(17.25-21.5)Hz frequency sub-bands.The reconstructed neuronal sources were segmented into 68 functionally parcellated brain regions,and the percentage of active sources for each region was computed.Further,the differences across the 68 regions among the four gaming conditions were evaluated using the percentage of active sources.The differences in activation for the dorsal-ventral pathways and some additional brain regions were observed among the four groups.The game with 2D objects and CA showed higher activation than that with 3D objects and RA,respectively.The dorsal pathway was found to be more active in contrast to the ventral pathway.The findings suggest that angular disparity and dimensionality in MR influence the engagement of dorsal-ventral visual pathways in such a way that angular disparity has a greater impact on cortical activation across this region than dimensionality.Also,higher activation for CA as compared to RA irrespective of dimensionality reflects the complexity of spatial information processing under CA.Similarly,greater activation was seen for 2D objects than 3D,indicating difficulty in information processing due to deficient visual features.展开更多
This paper presents a hardware architecture using mixed pipeline and parallel processing for complex division based on dichotomous coordinate descent(DCD) iterations. The objective of the proposed work is to achieve l...This paper presents a hardware architecture using mixed pipeline and parallel processing for complex division based on dichotomous coordinate descent(DCD) iterations. The objective of the proposed work is to achieve low-latency and resource optimized complex divider architecture in adaptive weight computation stage of minimum variance distortionless response(MVDR)algorithm. In this work, computation of complex division is modeled as a 2×2 linear equation solution problem and the DCD algorithm allows linear systems of equations to be solved with high degree of computational efficiency. The operations in the existing DCD algorithm are suitably parallel pipelined and the performance is optimized to 2 clock cycles per iteration. To improve the degree of parallelism, a parallel column vector read architecture is devised.The proposed work is implemented on the field programmable gate array(FPGA) platform and the results are compared with state-of-art literature. It concludes that the proposed architecture is suitable for complex division in adaptive weight computation stage of MVDR beamformer. We demonstrate the performance of the proposed architecture for MVDR beamformer employed in medical ultrasound imaging applications.展开更多
A robust scheme is proposed to jointly optimize transmit/receive beamformers for Mul-tiple Input Multiple Output(MIMO) downlinks where the available Channel State Information(CSI) at Base Station(BS)(CSIBS) is imperfe...A robust scheme is proposed to jointly optimize transmit/receive beamformers for Mul-tiple Input Multiple Output(MIMO) downlinks where the available Channel State Information(CSI) at Base Station(BS)(CSIBS) is imperfect.The criterion is to minimize the sum Mean Square Error(sum-MSE) over all users under a constraint on the total transmit power,which is a non-convex and non-linear problem.Observing from the first order optimization condition that the optimal trans-mit/receive beamformers are mutually dependent,the transmit/receive beamformers for each user are updated iteratively until the sum-MSE is minimized.Simulation results indicate that the proposed scheme can effectively mitigate the system performance loss induced by imperfect CSIBS.展开更多
In this paper, we consider a full.duplex multiple.input multiple.output(MIMO) relaying network with the decode.and.forward(DF) protocol. Due to the full.duplex transmissions, the self.interference from the relay trans...In this paper, we consider a full.duplex multiple.input multiple.output(MIMO) relaying network with the decode.and.forward(DF) protocol. Due to the full.duplex transmissions, the self.interference from the relay transmitter to the relay receiver degrades the system performance. We thus propose an iterative beamforming structure(IBS) to mitigate the self.interference. In this method, the receive beamforming at the relay is optimized to maximize the signal.to.interference.plus.noise.ratio(Max.SINR), while the transmit beamforming at the relay is optimized to maximize the signal.to.leakage.plusnoise.ratio(Max.SLNR). To further improve the performance, the receive and transmit beamforming matrices are optimized between Max.SINR and Max.SLNR in an iterative manner. Furthermore, in the presence of the residual self.interference, a low.complexity whitening.filter(WF) maximum likelihood(ML) detector is proposed. In this detector, a WF is designed to transform a colored interference.plus.noise to a white noise, while the singular value decomposition is used to convert coupled spatial subchannels to parallelindependent ones. From simulations, we find that the proposed IBS performs much better than the existing schemes. Also, the proposed low.complexity detector significantly reduces the complexity of the conventional ML(CML) detector from exponential time(an exponential function of the number of the source transmit antennas) to polynomial one while achieving a slightly better BER performance than the CML due to interference whitening.展开更多
Anovel beamforming algorithmnamed Delay Multiply and Sum(DMAS),which excels at enhancing the resolution and contrast of ultrasonic image,has recently been proposed.However,there are nested loops in this algorithm,so t...Anovel beamforming algorithmnamed Delay Multiply and Sum(DMAS),which excels at enhancing the resolution and contrast of ultrasonic image,has recently been proposed.However,there are nested loops in this algorithm,so the calculation complexity is higher compared to the Delay and Sum(DAS)beamformer which is widely used in industry.Thus,we proposed a simple vector-based method to lower its complexity.The key point is to transform the nested loops into several vector operations,which can be efficiently implemented on many parallel platforms,such as Graphics Processing Units(GPUs),and multi-core Central Processing Units(CPUs).Consequently,we considered to implement this algorithm on such a platform.In order to maximize the use of computing power,we use the GPUs andmulti-core CPUs inmixture.The platform used in our test is a low cost Personal Computer(PC),where a GPU and a multi-core CPU are installed.The results show that the hybrid use of a CPU and a GPU can get a significant performance improvement in comparison with using a GPU or using amulti-core CPU alone.The performance of the hybrid system is increased by about 47%–63%compared to a single GPU.When 32 elements are used in receiving,the fame rate basically can reach 30 fps.In the best case,the frame rate can be increased to 40 fps.展开更多
In this paper, a multiple beamforming technique is presented by using a direct data domain least squares (D3LS) approach. Direct data domain approach is very suitable for real time applications since it utilizes only ...In this paper, a multiple beamforming technique is presented by using a direct data domain least squares (D3LS) approach. Direct data domain approach is very suitable for real time applications since it utilizes only a single snapshot of data as opposed to statistical approaches where multiple measurements have to be taken and the covariance matrix has to be formed. It is also very effective especially in the case of blinking jammers where the statistical approaches will fail or needs to perform additional tasks to overcome it. It has been previously shown that the D3LS can successfully handle only one or two Signal of Interests (SOI). Here, we have developed a new technique where multiple SOI can be handled simultaneously. Numerical simulations have shown that the new approach can maximize the signals from the direction of the SOI at the same time minimizing the jammers. The new approach can be successfully applied in the satellite communications, Over the Horizon Radars (OTHR) as well as wireless communications to detect or track multiple targets simultaneously.展开更多
According to the algorithm of the fuze antenna beamforming and the requirement for the realtime performenee, a fuze antenna beamformer based on digital signal processor （DSP） was designed. The program was written in...According to the algorithm of the fuze antenna beamforming and the requirement for the realtime performenee, a fuze antenna beamformer based on digital signal processor （DSP） was designed. The program was written in C, and in order to reduce the operation time of DSP, the key part of the matrix operation was written in simple algorithm. The precise and speediness of DSP calculation results were analyzed through Matlab and the Profiling tools in Code Composer Studio （CCS）. The results show that the precise and the speediness both can satisfy the requirement for the fuze antennh beamforming.展开更多
An adaptive antenna array system adjusts the main lobe of radiation pattern in the direction of desired signal and points the nulls in the direction of undesired signals or interferers. The essential goal of beamformi...An adaptive antenna array system adjusts the main lobe of radiation pattern in the direction of desired signal and points the nulls in the direction of undesired signals or interferers. The essential goal of beamforming is to reduce the complexity of weighting process and to decrease the time needed for adjusting the antenna radiation pattern. In this article a new adaptive weighting algorithm is proposed for both least mean squares (LMS) and constant modulus (CM) algorithms. It is appropriate and applicable for antenna array systems with moving targets and also mobile applications as well as sensor networks. By predicting the relative velocity of source, the next location of the source will be estimated and the array weights will be determined using LMS or CM algorithm before arriving to the new point. For the next time associated to the new sampling point, evaluated weights will be used. Furthermore, by updating these weights between two consecutive times the effects of error propagation will be eliminated. Therefore, in addition to reduction in computational complexity at the time of weight allocation, relatively accurate weight allocation can be obtained. Simulation results of this investigation show that the angular error related to both LMS-based and CM-based algorithms is less than the conventional LMS and CM algorithms at different signal to noise ratios (SNRs). On the other hand, due to considering off-line process, online computational complexity of new algorithms is slightly low with respect to previous ones.展开更多
The real Direction Of Arrival (DOA) varies with time in mobile communication system. In such situation, the performance of conventional beamformers will be degraded obviously. Quantum Signal Processing (QSP) beamforme...The real Direction Of Arrival (DOA) varies with time in mobile communication system. In such situation, the performance of conventional beamformers will be degraded obviously. Quantum Signal Processing (QSP) beamformer is insensitive to DOA errors, thus it can achieve stable output performance in such circumstance. This letter verified the effectiveness and feasibility of the QSP beamformer by simulation results.展开更多
This article considers a wireless multi-hop/mesh network where single multi-antenna source-destination pair communicates through a selected relay subset using simple relay selection under the constraint of fixed relay...This article considers a wireless multi-hop/mesh network where single multi-antenna source-destination pair communicates through a selected relay subset using simple relay selection under the constraint of fixed relay＇s number. Compared with random selection, the simple relay selection can yield certain capacity advantages while linear zero-forcing （ZF） receiver and linear beamformer are considered at the relay. For match-filter （MF） beamformer and amplified-and-forward （AF） beamformer with a fixed number of relays, the capacities are given. Furthermore, we extend the simple selection methods to the relaying scheme with orthogonal-triangular （QR） beamformer and investigate these linear beamformer schemes over spatially correlated multi-input multi-output （MIMO） links for both the backward and forward channel over the two-bop MIMO relay networks.展开更多
In wideband multi-pair two-way relay networks, the performance of beamforming at a relay station(RS) is intimately related to the accuracy of the channel state information(CSI) available. The accuracy of CSI is determ...In wideband multi-pair two-way relay networks, the performance of beamforming at a relay station(RS) is intimately related to the accuracy of the channel state information(CSI) available. The accuracy of CSI is determined by Doppler spread, delay between beamforming and channel estimation, and density of pilot symbols,including transmit power of pilot symbols. The coefficient of the Gaussian-Markov CSI error model is modeled as a function of CSI delay, Doppler spread, and signal-to-noise ratio, and can be estimated in real time. In accordance with the real-time estimated coefficients of the error model, an adaptive robust maximum signal-to-interferenceand-noise ratio(Max-SINR) plus maximum signal-to-leakage-and-noise ratio(Max-SLNR) beamformer at an RS is proposed to track the variation of the CSI error. From simulation results and analysis, it is shown that: compared to existing non-adaptive beamformers, the proposed adaptive beamformer is more robust and performs much better in the sense of bit error rate(BER); with increase in the density of transmit pilot symbols, its BER and sum-rate performances tend to those of the beamformer of Max-SINR plus Max-SLNR with ideal CSI.展开更多
Beamforming using sensor array is widely used in spatial signal processing since it offers better spatial focusing capability than single sensor. However, in practical appli- cations for broadband signal, there always...Beamforming using sensor array is widely used in spatial signal processing since it offers better spatial focusing capability than single sensor. However, in practical appli- cations for broadband signal, there always exists a trade-off issue between the directivity capability of an array and its robustness on system errors. In this paper, in order to combine merits of different beamformers instead of trade-off their per- formances, we propose a constrained minimum-power com- bination method. We firstly analyze two optimal beamform- ers that maximize Directivity Factor （DF） and White Noise Gain （WNG） respectively. Then we propose a non-linear combination method, which automatically selects the best beamformer that has the minimum output power, so as to control the unwanted white noise amplification and keep the maximum DF if possible. Two solutions to the proposed com- bination strategy are given. They do not need to determine the correct trade-off factor used in linear combination method, and avoid challenge ~stimations on noise and target statistics required in adaptive beamforming. The performance of the proposed beamformer is evaluated in ideal noise fields and complicated noise fields respectively. It is shown that the proposed beamformer integrates merits of different beamform- ers. It always achieves the best speech quality and biggest noise reduction compared to other popular beamformers.展开更多
The rapid expansion of railways,especially High-Speed Railways(HSRs),has drawn considerable interest from both academic and industrial sectors.To meet the future vision of smart rail communications,the rail transport ...The rapid expansion of railways,especially High-Speed Railways(HSRs),has drawn considerable interest from both academic and industrial sectors.To meet the future vision of smart rail communications,the rail transport industry must innovate in key technologies to ensure high-quality transmissions for passengers and railway operations.These systems must function effectively under high mobility conditions while prioritizing safety,ecofriendliness,comfort,transparency,predictability,and reliability.On the other hand,the proposal of 6 G wireless technology introduces new possibilities for innovation in communication technologies,which may truly realize the current vision of HSR.Therefore,this article gives a review of the current advanced 6 G wireless communication technologies for HSR,including random access and switching,channel estimation and beamforming,integrated sensing and communication,and edge computing.The main application scenarios of these technologies are reviewed,as well as their current research status and challenges,followed by an outlook on future development directions.展开更多
A new method based on the iterative adaptive algorithm(IAA)and blocking matrix preprocessing(BMP)is proposed to study the suppression of multi-mainlobe interference.The algorithm is applied to precisely estimate the s...A new method based on the iterative adaptive algorithm(IAA)and blocking matrix preprocessing(BMP)is proposed to study the suppression of multi-mainlobe interference.The algorithm is applied to precisely estimate the spatial spectrum and the directions of arrival(DOA)of interferences to overcome the drawbacks associated with conventional adaptive beamforming(ABF)methods.The mainlobe interferences are identified by calculating the correlation coefficients between direction steering vectors(SVs)and rejected by the BMP pretreatment.Then,IAA is subsequently employed to reconstruct a sidelobe interference-plus-noise covariance matrix for the preferable ABF and residual interference suppression.Simulation results demonstrate the excellence of the proposed method over normal methods based on BMP and eigen-projection matrix perprocessing(EMP)under both uncorrelated and coherent circumstances.展开更多
Deconvolution methods are commonly used to improve the performance of phased array beamforming for sound source localization. However, for coherent sources localization, existing deconvolution methods are either highl...Deconvolution methods are commonly used to improve the performance of phased array beamforming for sound source localization. However, for coherent sources localization, existing deconvolution methods are either highly computationally demanding or sensitive to parameters.A deconvolution method, based on modifications of Clean based on Source Coherence(CLEAN-SC), is proposed for coherent sources localization. This method is called Coherence CLEAN-SC(C–CLEAN-SC). C–CLEAN-SC is able to locate coherent and incoherent sources in simulation and experimental cases. It has a high computational efficiency and does not require pre-set parameters.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
With the advancement of wireless communication technology,intelligent antenna technologies such as beam scanning and beamforming have been extensively applied in operators'5G networks,supported by mature technical...With the advancement of wireless communication technology,intelligent antenna technologies such as beam scanning and beamforming have been extensively applied in operators'5G networks,supported by mature technical solutions.However,the unique characteristics of the railway industry—such as the significant spacing between stations covered by wireless private networks,the high speed of train operations,and the necessity for high network reliability—pose elevated requirements for the construction of 5G private networks.An analysis was conducted on the challenges associated with railway 5G private network coverage.The investigation explored the adaptability of smart antenna technologies in various railway scenarios in combination with the principles and advantages of these technologies.This study analyzed the application prospects of smart antenna technologies in railway 5G private networks,taking into account the characteristics of various train operation scenarios.It evaluated the value of these technologies in enhancing the wireless coverage quality of railway 5G private networks in different scenarios.The findings aim to offer new insights and recommendations for the construction and deployment of railway 5G private networks.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
This paper begins with an overview of base station antennas,focusing on their structure and basic technical parameters.It then investigates the technical characteristics of three types of antennas—panel,Luneburg lens...This paper begins with an overview of base station antennas,focusing on their structure and basic technical parameters.It then investigates the technical characteristics of three types of antennas—panel,Luneburg lens,and innovative integrated antennas—in the context of railway 5G-R base station specifications.The advantages and disadvantages of these antenna types are compared and analyzed,and recommendations for the selection of 5G-R base station antennas are provided.Based on the special application scenarios of railway 5G-R base stations,this paper proposes connection methods between antennas and RRUs,and conducts a comparative analysis of antenna interface types.Furthermore,recommendations are provided for configuring the antenna information management module to meet the intelligent operation and maintenance requirements of the 5G-R system.The findings can serve as a reference for the selection and operation of antennas at railway 5G-R base stations.展开更多
基金supported by the National Nature Science Foundation of China (60472101)President Award of ChineseAcademy of Sciences(O729031511).
文摘Adaptive broadband beamforraing is a key issue in array applications. The adaptive broadband beamformer with tapped delay line （TDL） structure for nonuniform linear array （NLA） is designed according to the rule of minimizing the beamformer＇s output power while keeping the distortionless response （DR） in the direction of desired signal and keeping the constant beamwidth （CB） with the prescribed sidelobe level over the whole operating band. This kind of beamforming problem can be solved with the interior-point method after being converted to the form of standard second order cone programming （SOCP）. The computer simulations are presented which illustrate the effectiveness of our beamformer.
基金A.T.was supported by DST-INSPIRE Program sponsored by Department of Science&Technology,Government of India,Fellowship ID:IF150444,URL:https://www.online-inspire.gov.in/.
文摘In performing a gaming task,mental rotation(MR)is one of the important aspects of visuospatial processing.MR involves dorsal-ventral pathways of the brain.Visual objects/models used in computer-games play a crucial role in gaming experience of the users.The visuospatial characteristics of the objects used in the computer-game influence the engagement of dorsal-ventral visual pathways.The current study investigates how the objects’visuospatial characteristics(i.e.,angular disparity and dimensionality)in an MR-based computer-game influence the cortical activities in dorsalventral visual pathways.Both the factors have two levels,angular disparity:convex angle(CA)vs.reflex angle(RA)and dimensionality:2D vs.3D.Sixty healthy adults,aged,18-29 years(M=21.6)were recruited for the study and randomly assigned to four gaming conditions i.e.,15 participants in each group.The multichannel electroencephalogram(EEG)data were recorded from 60 healthy adults while playing the game.The source reconstruction was done for∼3000 sources inside the brain using the Dynamic Imaging of Coherent Sources(DICS)beamforming method forθ1(4-5.75),θ2(5.75-7.5),α1(7.5-9),α2(9-11),α3(11-13),β1(13-17.25),β2(17.25-21.5)Hz frequency sub-bands.The reconstructed neuronal sources were segmented into 68 functionally parcellated brain regions,and the percentage of active sources for each region was computed.Further,the differences across the 68 regions among the four gaming conditions were evaluated using the percentage of active sources.The differences in activation for the dorsal-ventral pathways and some additional brain regions were observed among the four groups.The game with 2D objects and CA showed higher activation than that with 3D objects and RA,respectively.The dorsal pathway was found to be more active in contrast to the ventral pathway.The findings suggest that angular disparity and dimensionality in MR influence the engagement of dorsal-ventral visual pathways in such a way that angular disparity has a greater impact on cortical activation across this region than dimensionality.Also,higher activation for CA as compared to RA irrespective of dimensionality reflects the complexity of spatial information processing under CA.Similarly,greater activation was seen for 2D objects than 3D,indicating difficulty in information processing due to deficient visual features.
基金supported by Microelectronics Division of the Ministry of Electronics and Information Technology,Government of India,under SMDP-C2SD Project(9(1)/2014–MDD)
文摘This paper presents a hardware architecture using mixed pipeline and parallel processing for complex division based on dichotomous coordinate descent(DCD) iterations. The objective of the proposed work is to achieve low-latency and resource optimized complex divider architecture in adaptive weight computation stage of minimum variance distortionless response(MVDR)algorithm. In this work, computation of complex division is modeled as a 2×2 linear equation solution problem and the DCD algorithm allows linear systems of equations to be solved with high degree of computational efficiency. The operations in the existing DCD algorithm are suitably parallel pipelined and the performance is optimized to 2 clock cycles per iteration. To improve the degree of parallelism, a parallel column vector read architecture is devised.The proposed work is implemented on the field programmable gate array(FPGA) platform and the results are compared with state-of-art literature. It concludes that the proposed architecture is suitable for complex division in adaptive weight computation stage of MVDR beamformer. We demonstrate the performance of the proposed architecture for MVDR beamformer employed in medical ultrasound imaging applications.
基金the National Natural Science Foundation of China(No.60572156)
文摘A robust scheme is proposed to jointly optimize transmit/receive beamformers for Mul-tiple Input Multiple Output(MIMO) downlinks where the available Channel State Information(CSI) at Base Station(BS)(CSIBS) is imperfect.The criterion is to minimize the sum Mean Square Error(sum-MSE) over all users under a constraint on the total transmit power,which is a non-convex and non-linear problem.Observing from the first order optimization condition that the optimal trans-mit/receive beamformers are mutually dependent,the transmit/receive beamformers for each user are updated iteratively until the sum-MSE is minimized.Simulation results indicate that the proposed scheme can effectively mitigate the system performance loss induced by imperfect CSIBS.
基金supported in part by the National Natural Science Foundation of China (Nos. 61271230, 61472190, and 61501238)the Open Research Fund of National Key Laboratory of Electromagnetic Environment, China Research Institute of Radiowave Propagation (No. 201500013)+4 种基金the open research fund of National Mobile Communications Research Laboratory, Southeast University, China (No. 2013D02)the Research Fund for the Doctoral Program of Higher Education of China (No. 20113219120019)the Foundation of Cloud Computing and Big Data for Agriculture and Forestry (117-612014063)the China Postdoctoral Science Foundation (2016M591852)Postdoctoral research funding program of Jiangsu Province (1601257C)
文摘In this paper, we consider a full.duplex multiple.input multiple.output(MIMO) relaying network with the decode.and.forward(DF) protocol. Due to the full.duplex transmissions, the self.interference from the relay transmitter to the relay receiver degrades the system performance. We thus propose an iterative beamforming structure(IBS) to mitigate the self.interference. In this method, the receive beamforming at the relay is optimized to maximize the signal.to.interference.plus.noise.ratio(Max.SINR), while the transmit beamforming at the relay is optimized to maximize the signal.to.leakage.plusnoise.ratio(Max.SLNR). To further improve the performance, the receive and transmit beamforming matrices are optimized between Max.SINR and Max.SLNR in an iterative manner. Furthermore, in the presence of the residual self.interference, a low.complexity whitening.filter(WF) maximum likelihood(ML) detector is proposed. In this detector, a WF is designed to transform a colored interference.plus.noise to a white noise, while the singular value decomposition is used to convert coupled spatial subchannels to parallelindependent ones. From simulations, we find that the proposed IBS performs much better than the existing schemes. Also, the proposed low.complexity detector significantly reduces the complexity of the conventional ML(CML) detector from exponential time(an exponential function of the number of the source transmit antennas) to polynomial one while achieving a slightly better BER performance than the CML due to interference whitening.
基金This work was supported by the Science and Technology Research Program of Chongqing Municipal Education Commission(Grant No.KJQN201801606)the Natural Sci-ence Foundation Project of CQ CSTC(cstc2017jcyjAX0092)+3 种基金the Scientific Research Program of Chongqing University of Education(Grant Nos.KY201924C,2017XJZDWT02)the Science and Technology Research Program of Chongqing Municipal Education Commission(Grant No.KJ1601410)the Project‘Future School(Infant Education)’of National Center For Schooling Development Programme of China(Grant No.CSDP18FC2202)the Chongqing Electronics Engineering Technology Research Center for Interactive Learning,and the Chongqing Big Data Engineering Laboratory for Children.
文摘Anovel beamforming algorithmnamed Delay Multiply and Sum(DMAS),which excels at enhancing the resolution and contrast of ultrasonic image,has recently been proposed.However,there are nested loops in this algorithm,so the calculation complexity is higher compared to the Delay and Sum(DAS)beamformer which is widely used in industry.Thus,we proposed a simple vector-based method to lower its complexity.The key point is to transform the nested loops into several vector operations,which can be efficiently implemented on many parallel platforms,such as Graphics Processing Units(GPUs),and multi-core Central Processing Units(CPUs).Consequently,we considered to implement this algorithm on such a platform.In order to maximize the use of computing power,we use the GPUs andmulti-core CPUs inmixture.The platform used in our test is a low cost Personal Computer(PC),where a GPU and a multi-core CPU are installed.The results show that the hybrid use of a CPU and a GPU can get a significant performance improvement in comparison with using a GPU or using amulti-core CPU alone.The performance of the hybrid system is increased by about 47%–63%compared to a single GPU.When 32 elements are used in receiving,the fame rate basically can reach 30 fps.In the best case,the frame rate can be increased to 40 fps.
文摘In this paper, a multiple beamforming technique is presented by using a direct data domain least squares (D3LS) approach. Direct data domain approach is very suitable for real time applications since it utilizes only a single snapshot of data as opposed to statistical approaches where multiple measurements have to be taken and the covariance matrix has to be formed. It is also very effective especially in the case of blinking jammers where the statistical approaches will fail or needs to perform additional tasks to overcome it. It has been previously shown that the D3LS can successfully handle only one or two Signal of Interests (SOI). Here, we have developed a new technique where multiple SOI can be handled simultaneously. Numerical simulations have shown that the new approach can maximize the signals from the direction of the SOI at the same time minimizing the jammers. The new approach can be successfully applied in the satellite communications, Over the Horizon Radars (OTHR) as well as wireless communications to detect or track multiple targets simultaneously.
基金the Ministerial Level Advanced Research Foundation(51204BQ01)
文摘According to the algorithm of the fuze antenna beamforming and the requirement for the realtime performenee, a fuze antenna beamformer based on digital signal processor （DSP） was designed. The program was written in C, and in order to reduce the operation time of DSP, the key part of the matrix operation was written in simple algorithm. The precise and speediness of DSP calculation results were analyzed through Matlab and the Profiling tools in Code Composer Studio （CCS）. The results show that the precise and the speediness both can satisfy the requirement for the fuze antennh beamforming.
文摘An adaptive antenna array system adjusts the main lobe of radiation pattern in the direction of desired signal and points the nulls in the direction of undesired signals or interferers. The essential goal of beamforming is to reduce the complexity of weighting process and to decrease the time needed for adjusting the antenna radiation pattern. In this article a new adaptive weighting algorithm is proposed for both least mean squares (LMS) and constant modulus (CM) algorithms. It is appropriate and applicable for antenna array systems with moving targets and also mobile applications as well as sensor networks. By predicting the relative velocity of source, the next location of the source will be estimated and the array weights will be determined using LMS or CM algorithm before arriving to the new point. For the next time associated to the new sampling point, evaluated weights will be used. Furthermore, by updating these weights between two consecutive times the effects of error propagation will be eliminated. Therefore, in addition to reduction in computational complexity at the time of weight allocation, relatively accurate weight allocation can be obtained. Simulation results of this investigation show that the angular error related to both LMS-based and CM-based algorithms is less than the conventional LMS and CM algorithms at different signal to noise ratios (SNRs). On the other hand, due to considering off-line process, online computational complexity of new algorithms is slightly low with respect to previous ones.
基金Sponsored by the National Natural Science Foundation of China (No.60302006 and No.60462002).
文摘The real Direction Of Arrival (DOA) varies with time in mobile communication system. In such situation, the performance of conventional beamformers will be degraded obviously. Quantum Signal Processing (QSP) beamformer is insensitive to DOA errors, thus it can achieve stable output performance in such circumstance. This letter verified the effectiveness and feasibility of the QSP beamformer by simulation results.
基金the National Natural Science Foundation of China (60772061)the OpenResearch Fund of National Mobile Communications Research Laboratory of Southeast University, the National Basic Research Program of China (2007CB310607)the Jiangsu Post doctoral Research Programs
文摘This article considers a wireless multi-hop/mesh network where single multi-antenna source-destination pair communicates through a selected relay subset using simple relay selection under the constraint of fixed relay＇s number. Compared with random selection, the simple relay selection can yield certain capacity advantages while linear zero-forcing （ZF） receiver and linear beamformer are considered at the relay. For match-filter （MF） beamformer and amplified-and-forward （AF） beamformer with a fixed number of relays, the capacities are given. Furthermore, we extend the simple selection methods to the relaying scheme with orthogonal-triangular （QR） beamformer and investigate these linear beamformer schemes over spatially correlated multi-input multi-output （MIMO） links for both the backward and forward channel over the two-bop MIMO relay networks.
基金Project supported by the Open Research Fund of National Mobile Communications Research Laboratory,Southeast University,China(No.2013D02)the Open Research Fund of National Key Laboratory of Electromagnetic Environment,China Research Institute of Radiowave Propagation(No.201500013)+2 种基金the National Natural Science Foundation of China(Nos.61271230,61472190,and 61501238)the Research Fund for the Doctoral Program of Higher Education of China(No.20113219120019)the Jiangsu Provincial Science Foundation Project,China(No.BK20150786)
文摘In wideband multi-pair two-way relay networks, the performance of beamforming at a relay station(RS) is intimately related to the accuracy of the channel state information(CSI) available. The accuracy of CSI is determined by Doppler spread, delay between beamforming and channel estimation, and density of pilot symbols,including transmit power of pilot symbols. The coefficient of the Gaussian-Markov CSI error model is modeled as a function of CSI delay, Doppler spread, and signal-to-noise ratio, and can be estimated in real time. In accordance with the real-time estimated coefficients of the error model, an adaptive robust maximum signal-to-interferenceand-noise ratio(Max-SINR) plus maximum signal-to-leakage-and-noise ratio(Max-SLNR) beamformer at an RS is proposed to track the variation of the CSI error. From simulation results and analysis, it is shown that: compared to existing non-adaptive beamformers, the proposed adaptive beamformer is more robust and performs much better in the sense of bit error rate(BER); with increase in the density of transmit pilot symbols, its BER and sum-rate performances tend to those of the beamformer of Max-SINR plus Max-SLNR with ideal CSI.
文摘Beamforming using sensor array is widely used in spatial signal processing since it offers better spatial focusing capability than single sensor. However, in practical appli- cations for broadband signal, there always exists a trade-off issue between the directivity capability of an array and its robustness on system errors. In this paper, in order to combine merits of different beamformers instead of trade-off their per- formances, we propose a constrained minimum-power com- bination method. We firstly analyze two optimal beamform- ers that maximize Directivity Factor （DF） and White Noise Gain （WNG） respectively. Then we propose a non-linear combination method, which automatically selects the best beamformer that has the minimum output power, so as to control the unwanted white noise amplification and keep the maximum DF if possible. Two solutions to the proposed com- bination strategy are given. They do not need to determine the correct trade-off factor used in linear combination method, and avoid challenge ~stimations on noise and target statistics required in adaptive beamforming. The performance of the proposed beamformer is evaluated in ideal noise fields and complicated noise fields respectively. It is shown that the proposed beamformer integrates merits of different beamform- ers. It always achieves the best speech quality and biggest noise reduction compared to other popular beamformers.
基金National Natural Science Foundation of China(U2468201,62122012,62221001).
文摘The rapid expansion of railways,especially High-Speed Railways(HSRs),has drawn considerable interest from both academic and industrial sectors.To meet the future vision of smart rail communications,the rail transport industry must innovate in key technologies to ensure high-quality transmissions for passengers and railway operations.These systems must function effectively under high mobility conditions while prioritizing safety,ecofriendliness,comfort,transparency,predictability,and reliability.On the other hand,the proposal of 6 G wireless technology introduces new possibilities for innovation in communication technologies,which may truly realize the current vision of HSR.Therefore,this article gives a review of the current advanced 6 G wireless communication technologies for HSR,including random access and switching,channel estimation and beamforming,integrated sensing and communication,and edge computing.The main application scenarios of these technologies are reviewed,as well as their current research status and challenges,followed by an outlook on future development directions.
基金The National Natural Science Foundation of China(No.U19B2031).
文摘A new method based on the iterative adaptive algorithm(IAA)and blocking matrix preprocessing(BMP)is proposed to study the suppression of multi-mainlobe interference.The algorithm is applied to precisely estimate the spatial spectrum and the directions of arrival(DOA)of interferences to overcome the drawbacks associated with conventional adaptive beamforming(ABF)methods.The mainlobe interferences are identified by calculating the correlation coefficients between direction steering vectors(SVs)and rejected by the BMP pretreatment.Then,IAA is subsequently employed to reconstruct a sidelobe interference-plus-noise covariance matrix for the preferable ABF and residual interference suppression.Simulation results demonstrate the excellence of the proposed method over normal methods based on BMP and eigen-projection matrix perprocessing(EMP)under both uncorrelated and coherent circumstances.
基金supported by the National Science and Technology Major Project of China (No. 2017-II-003–0015)。
文摘Deconvolution methods are commonly used to improve the performance of phased array beamforming for sound source localization. However, for coherent sources localization, existing deconvolution methods are either highly computationally demanding or sensitive to parameters.A deconvolution method, based on modifications of Clean based on Source Coherence(CLEAN-SC), is proposed for coherent sources localization. This method is called Coherence CLEAN-SC(C–CLEAN-SC). C–CLEAN-SC is able to locate coherent and incoherent sources in simulation and experimental cases. It has a high computational efficiency and does not require pre-set parameters.
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.
文摘With the advancement of wireless communication technology,intelligent antenna technologies such as beam scanning and beamforming have been extensively applied in operators'5G networks,supported by mature technical solutions.However,the unique characteristics of the railway industry—such as the significant spacing between stations covered by wireless private networks,the high speed of train operations,and the necessity for high network reliability—pose elevated requirements for the construction of 5G private networks.An analysis was conducted on the challenges associated with railway 5G private network coverage.The investigation explored the adaptability of smart antenna technologies in various railway scenarios in combination with the principles and advantages of these technologies.This study analyzed the application prospects of smart antenna technologies in railway 5G private networks,taking into account the characteristics of various train operation scenarios.It evaluated the value of these technologies in enhancing the wireless coverage quality of railway 5G private networks in different scenarios.The findings aim to offer new insights and recommendations for the construction and deployment of railway 5G private networks.
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.
文摘This paper begins with an overview of base station antennas,focusing on their structure and basic technical parameters.It then investigates the technical characteristics of three types of antennas—panel,Luneburg lens,and innovative integrated antennas—in the context of railway 5G-R base station specifications.The advantages and disadvantages of these antenna types are compared and analyzed,and recommendations for the selection of 5G-R base station antennas are provided.Based on the special application scenarios of railway 5G-R base stations,this paper proposes connection methods between antennas and RRUs,and conducts a comparative analysis of antenna interface types.Furthermore,recommendations are provided for configuring the antenna information management module to meet the intelligent operation and maintenance requirements of the 5G-R system.The findings can serve as a reference for the selection and operation of antennas at railway 5G-R base stations.
