期刊文献+
共找到40篇文章
< 1 2 >
每页显示 20 50 100
Adversarial Training-Aided Time-Varying Channel Prediction for TDD/FDD Systems 被引量:3
1
作者 Zhen Zhang Yuxiang Zhang +1 位作者 Jianhua Zhang Feifei Gao 《China Communications》 SCIE CSCD 2023年第6期100-115,共16页
In this paper, a time-varying channel prediction method based on conditional generative adversarial network(CPcGAN) is proposed for time division duplexing/frequency division duplexing(TDD/FDD) systems. CPc GAN utiliz... In this paper, a time-varying channel prediction method based on conditional generative adversarial network(CPcGAN) is proposed for time division duplexing/frequency division duplexing(TDD/FDD) systems. CPc GAN utilizes a discriminator to calculate the divergence between the predicted downlink channel state information(CSI) and the real sample distributions under a conditional constraint that is previous uplink CSI. The generator of CPcGAN learns the function relationship between the conditional constraint and the predicted downlink CSI and reduces the divergence between predicted CSI and real CSI.The capability of CPcGAN fitting data distribution can capture the time-varying and multipath characteristics of the channel well. Considering the propagation characteristics of real channel, we further develop a channel prediction error indicator to determine whether the generator reaches the best state. Simulations show that the CPcGAN can obtain higher prediction accuracy and lower system bit error rate than the existing methods under the same user speeds. 展开更多
关键词 channel prediction time-varying channel conditional generative adversarial network multipath channel deep learning
下载PDF
Robust Beamforming Under Channel Prediction Errors for Time-Varying MIMO System 被引量:1
2
作者 ZHU Yuting LI Zeng ZHANG Hongtao 《ZTE Communications》 2023年第3期77-85,共9页
The accuracy of acquired channel state information(CSI)for beamforming design is essential for achievable performance in multiple-input multiple-output(MIMO)systems.However,in a high-speed moving scene with time-divis... The accuracy of acquired channel state information(CSI)for beamforming design is essential for achievable performance in multiple-input multiple-output(MIMO)systems.However,in a high-speed moving scene with time-division duplex(TDD)mode,the acquired CSI depending on the channel reciprocity is inevitably outdated,leading to outdated beamforming design and then performance degradation.In this paper,a robust beamforming design under channel prediction errors is proposed for a time-varying MIMO system to combat the degradation further,based on the channel prediction technique.Specifically,the statistical characteristics of historical channel prediction errors are exploited and modeled.Moreover,to deal with random error terms,deterministic equivalents are adopted to further explore potential beamforming gain through the statistical information and ultimately derive the robust design aiming at maximizing weighted sum-rate performance.Simulation results show that the proposed beamforming design can maintain outperformance during the downlink transmission time even when channels vary fast,compared with the traditional beamforming design. 展开更多
关键词 time-varying channels time-division duplex robust beamforming channel prediction errors weighted sum-rate maximization
下载PDF
Tensor Decomposition-Based Channel Estimation and Sensing for Millimeter Wave MIMO-OFDM V2I Systems
3
作者 WANG Jilin ZENG Xianlong +2 位作者 YANG Yonghui PENG Lin LI Lingxiang 《ZTE Communications》 2024年第3期56-68,共13页
An integrated sensing and communication(ISAC)scheme for a millimeter wave(mmWave)multiple-input multiple-output orthogonal frequency division multiplexing(MIMO-OFDM)Vehicle-to-Infrastructure(V2I)system is presented,in... An integrated sensing and communication(ISAC)scheme for a millimeter wave(mmWave)multiple-input multiple-output orthogonal frequency division multiplexing(MIMO-OFDM)Vehicle-to-Infrastructure(V2I)system is presented,in which both the access point(AP)and the vehicle are equipped with large antenna arrays and employ hybrid analog and digital beamforming structures to compensate the path loss,meanwhile compromise between hardware complexity and system performance.Based on the sparse scattering nature of the mmWave channel,the received signal at the AP is organized to a four-order tensor by the introduced novel frame structure.A CANDECOMP/PARAFAC(CP)decomposition-based method is proposed for time-varying channel parameter extraction,including angles of departure/arrival(AoDs/AoAs),Doppler shift,time delay and path gain.Then leveraging the estimates of channel parameters,a nonlinear weighted least-square problem is proposed to recover the location accurately,heading and velocity of vehicles.Simulation results show that the proposed methods are effective and efficient in time-varying channel estimation and vehicle sensing in mmWave MIMOOFDM V2I systems. 展开更多
关键词 MIMO-OFDM Vehicle-to-Infrastructure(V2I)systems ISAC time-varying channel estimation CANDECOMP/PARAFAC(CP)decomposition
下载PDF
Neural Network and GBSM Based Time-Varying and Stochastic Channel Modeling for 5G Millimeter Wave Communications 被引量:7
4
作者 Xiongwen Zhao Fei Du +4 位作者 Suiyan Geng Ningyao Sun Yu Zhang Zihao Fu Guangjian Wang 《China Communications》 SCIE CSCD 2019年第6期80-90,共11页
In this work,a frame work for time-varying channel modeling and simulation is proposed by using neural network(NN)to overcome the shortcomings in geometry based stochastic model(GBSM)and simulation approach.Two NN mod... In this work,a frame work for time-varying channel modeling and simulation is proposed by using neural network(NN)to overcome the shortcomings in geometry based stochastic model(GBSM)and simulation approach.Two NN models are developed for modeling of path loss together with shadow fading(SF)and joint small scale channel parameters.The NN models can predict path loss plus SF and small scale channel parameters accurately compared with measurement at 26 GHz performed in an outdoor microcell.The time-varying path loss and small scale channel parameters generated by the NN models are proposed to replace the empirical path loss and channel parameter random numbers in GBSM-based framework to playback the measured channel and match with its environment.Moreover,the sparse feature of clusters,delay and angular spread,channel capacity are investigated by a virtual array measurement at 28 GHz in a large waiting hall. 展开更多
关键词 time-varying channel NEURAL network CLUSTER channel modeling VIRTUAL array measurement 5G
下载PDF
SUBSPACE METHOD FOR BLIND IDENTIFICATION OF CDMA TIME-VARYING CHANNELS 被引量:2
5
作者 Liu Yulin Peng Qicong (School of Communication and Information Engineering, UEST of China, Chengdu 610054) 《Journal of Electronics(China)》 2002年第1期61-67,共7页
A new blind method is proposed for identification of CDMA Time-Varying (TV)channels in this paper. By representing the TV channel's impulse responses in the delay-Doppler spread domain, the discrete-time canonical... A new blind method is proposed for identification of CDMA Time-Varying (TV)channels in this paper. By representing the TV channel's impulse responses in the delay-Doppler spread domain, the discrete-time canonical model of CDMA-TV systems is developed and a subspace method to identify blindly the Time-Invariant (TI) coordinates is proposed. Unlike existing basis expansion methods, this new algorithm does not require .estimation of the base frequencies, neither need the assumption of linearly varying delays across symbols. The algorithm offers definite explanation of the expansion coordinates. Simulation demonstrates the effectiveness of the algorithm. 展开更多
关键词 CDMA time-varying channels Blind identification Delay-Doppler spread domain Subspace method
下载PDF
Antenna calibration using channel prediction for time-varying channels 被引量:1
6
作者 Yamin SONG Xia LEI +1 位作者 Zhaofu KONG Binhong DONG 《Journal of Modern Transportation》 2012年第4期213-219,共7页
Traditional antenna calibration methods for time division duplex (TDD) systems asSume that the flee-space channel remains the same during calibration, which is unreasonable under the high-speed rail and other time-v... Traditional antenna calibration methods for time division duplex (TDD) systems asSume that the flee-space channel remains the same during calibration, which is unreasonable under the high-speed rail and other time-varying channel scenarios, and will cause calibration error due to time variability. This paper proposes an antenna calibration method for time-varying channels. In the proposed method, the transceiver first sequentially sends a pilot signal to ob- tain equivalent do^vnlink and uplink channel responses. Then, by predicting the downlink (uplink) channel response fed back from the receiver using the channel prediction algorithm, the transmitter obtains the channel response correspond- ing to the channel response on uplink (downlink). Finally, the transmitter calculates the transmission calibration factor through the prediction value. Compared with the traditional antenna calibration method, this method can improve the accuracy of the calibration factor. Simulation results show that the performance degradation of antenna calibration can be caused by time-varying channels and the proposed method can well compensate for the performance loss and sig- nificantly improve the antenna calibration performance for time-varying channels. 展开更多
关键词 TDD channel reciprocity time-varying channel channel prediction antenna calibration
下载PDF
Deep learning-based time-varying channel estimation with basis expansion model for MIMO-OFDM system 被引量:1
7
作者 HU Bo YANG Lihua +1 位作者 REN Lulu NIE Qian 《High Technology Letters》 EI CAS 2022年第3期288-294,共7页
For high-speed mobile MIMO-OFDM system,a low-complexity deep learning(DL) based timevarying channel estimation scheme is proposed.To reduce the number of estimated parameters,the basis expansion model(BEM) is employed... For high-speed mobile MIMO-OFDM system,a low-complexity deep learning(DL) based timevarying channel estimation scheme is proposed.To reduce the number of estimated parameters,the basis expansion model(BEM) is employed to model the time-varying channel,which converts the channel estimation into the estimation of the basis coefficient.Specifically,the initial basis coefficients are firstly used to train the neural network in an offline manner,and then the high-precision channel estimation can be obtained by small number of inputs.Moreover,the linear minimum mean square error(LMMSE) estimated channel is considered for the loss function in training phase,which makes the proposed method more practical.Simulation results show that the proposed method has a better performance and lower computational complexity compared with the available schemes,and it is robust to the fast time-varying channel in the high-speed mobile scenarios. 展开更多
关键词 MIMO-OFDM high-speed mobile time-varying channel deep learning(DL) basis expansion model(BEM)
下载PDF
Pilot Placement for Time-Varying MIMO OFDM Channels with Virtual Subcarriers 被引量:1
8
作者 Alieh Moradi Hamidreza Bakhshi Vahid Najafpoor 《Communications and Network》 2011年第1期31-38,共8页
The rapid time-variation of a fading multipath environment can impair the performance of multiple-input multiple-output orthogonal frequency division multiplexing (MIMO OFDM). This paper proposes a pilot placement met... The rapid time-variation of a fading multipath environment can impair the performance of multiple-input multiple-output orthogonal frequency division multiplexing (MIMO OFDM). This paper proposes a pilot placement method for MIMO OFDM systems under time-varying channels with the guard band. The time-varying channel is described by complex exponential basis expansion model (BEM). We discuss the least square (LS) channel estimation to obtain the minimum mean square error (MSE) and derive the pilot allocation that can satisfy the minimum MSE with regard to guard band in time-varying channels. It is shown that optimal pilot clusters can distribute non-uniformly in frequency domain and minimize the MSE. We generalize our scheme over G OFDM symbols and compare it with comb pilots. It is demonstrated that the proposed approach is more effective than previous work. Simulation results validate our theoretical analysis. 展开更多
关键词 GUARD Band MIMO OFDM PILOT time-varying channel Virtual Subcarriers
下载PDF
Multiple Vandermonde Decomposition Based Channel Estimation for Mm Wave MIMO High-Mobility Communication in 5G and Beyond 被引量:2
9
作者 Zhao Yi Xiaojun Jing 《China Communications》 SCIE CSCD 2023年第4期12-25,共14页
Millimeter wave(mmWave)massive massive multiple input multiple output(MIMO)technique has been regarded as the viable solution for vehicular communications in 5G and beyond.To achieve the substantial increase in date r... Millimeter wave(mmWave)massive massive multiple input multiple output(MIMO)technique has been regarded as the viable solution for vehicular communications in 5G and beyond.To achieve the substantial increase in date rates,it is important to take an effective channel state information(CSI).However,existing channel estimation strategies are unavailable since the users high-mobility.To solve above issues,in this paper,inspired by a specific antenna structure,we propose a novel approach for fast time-varying channel estimation.Specifically,by considering the vehicle scenario with high-mobility,a corresponding mathematical model is firstly established.Then,based on the special structural of the sparse array,the switch network is used to replace the convention phase shifter of mmWave hybrid system,which can effectively reduce the number of radio-frequency(RF)chains and antennas.Furthermore,by solving the semidefinite programming(SDP)duality problem,the Doppler frequency and path parameters are effectively estimated.Simulation results are shown that the computational complexity and estimation accuracy of the proposed algorithm is superior than that of the traditional schemes. 展开更多
关键词 MIMO mmWave channel estimation HIGH-MOBILITY time-variant
下载PDF
Fragmental Weight-Conservation Combining Scheme for Statistical Signal Transmissions under Fast Time-Varying Channels
10
作者 Xingwei Wang Ting Zhou +3 位作者 Tianheng Xu Songlin Feng Honglin Hu Yanliang Jin 《China Communications》 SCIE CSCD 2020年第1期118-128,共11页
Statistical Signal Transmission(SST)is a technique based on orthogonal frequency-division multiplexing(OFDM)and adopts cyclostationary features,which can transmit extra information without additional bandwidth.However... Statistical Signal Transmission(SST)is a technique based on orthogonal frequency-division multiplexing(OFDM)and adopts cyclostationary features,which can transmit extra information without additional bandwidth.However,the more complicated environment in 5G communication systems,especially the fast time-varying scenarios,will dramatically degrade the performance of the SST.In this paper,we propose a fragmental weight-conservation combining(FWCC)scheme for SST,to overcome its performance degradation under fast time-varying channels.The proposed FWCC scheme consists of three phases:1、incise the received OFDM stream into pieces;2、endue different weights for fine and contaminated pieces,respectively;3、combine cyclic autocorrelation function energies of all the pieces;and 4、compute the final feature and demodulate data of SST.Through these procedures above,the detection accuracy of SST will be theoretically refined under fast time-varying channels.Such an inference is confirmed through numerical results in this paper.It is demonstrated that the BER performance of proposed scheme outperforms that of the original scheme both in ideal channel estimation conditions and in imperfect channel estimation conditions.In addition,we also find the experiential optimal weight distribution strategy for the proposed FWCC scheme,which facilitates practical applications. 展开更多
关键词 Cyclostationary features statistical signal transmission(SST) weight conservation time-varying channels
下载PDF
Sparse Recovery of Linear Time-Varying Channel in OFDM System
11
作者 Jiansheng Hu Zuxun Song Shuxia Guo 《Journal of Beijing Institute of Technology》 EI CAS 2017年第2期245-251,共7页
In order to improve the performance of linear time-varying(LTV)channel estimation,based on the sparsity of channel taps in time domain,a sparse recovery method of LTV channel in orthogonal frequency division multipl... In order to improve the performance of linear time-varying(LTV)channel estimation,based on the sparsity of channel taps in time domain,a sparse recovery method of LTV channel in orthogonal frequency division multiplexing(OFDM)system is proposed.Firstly,based on the compressive sensing theory,the average of the channel taps over one symbol duration in the LTV channel model is estimated.Secondly,in order to deal with the inter-carrier interference(ICI),the group-pilot design criterion is used based on the minimization of mutual coherence of the measurement.Finally,an efficient pilot pattern optimization algorithm is proposed by a dual layer loops iteration.The simulation results show that the new method uses less pilots,has a smaller bit error ratio(BER),and greater ability to deal with Doppler frequency shift than the traditional method does. 展开更多
关键词 orthogonal frequency division multiplexing OFDM linear time-varying (LTV) channel sparse recovery pilots design
下载PDF
Methods to Improve the Long Distance Time-Varying Channel Transmission Performance of Expendable Profiler
12
作者 ZHENG Yu ZHANG Xiao-yang +2 位作者 WANG Xiao-rui GUO Xing-xin LI Hong-zhi 《China Ocean Engineering》 SCIE EI CSCD 2019年第6期753-761,共9页
To improve the transmission performance of XCTD channel, this paper proposes a method to measure directly and fit the channel transmission characteristics by using frequency sweeping method. Sinusoidal signals with a ... To improve the transmission performance of XCTD channel, this paper proposes a method to measure directly and fit the channel transmission characteristics by using frequency sweeping method. Sinusoidal signals with a frequency range of 100 Hz to 10 k Hz and an interval of 100 Hz are used to measure transmission characteristics of channels with lengths of 300 m, 800 m, 1300 m, and 1800 m. The correctness of the fitted channel characteristics by transmitting square wave, composite waves of different frequencies, and ASK modulation are verified. The results show that when the frequency of the signal is below 1500 Hz, the channel has very little effect on the signal. The signal compensated for amplitude and phase at the receiver is not as good as the uncompensated signal.Alternatively, when the signal frequency is above 1500 Hz, the channel distorts the signal. The quality of signal compensated for amplitude and phase at receiver is better than that of the uncompensated signal. Thus, we can select the appropriate frequency for XCTD system and the appropriate way to process the received signals. Signals below1500 Hz can be directly used at the receiving end. Signals above 1500 Hz are used after amplitude and phase compensation at the receiving end. 展开更多
关键词 expandable conductivity temperature depth(XCTD)profiler time-varying channel modeling frequency sweeping method amplitude and phase compensation transmission performance
下载PDF
A Receiver Structure for Frequency-Flat Time-Varying Rayleigh Channels and Performance Analysis
13
作者 Xiaofei Shao Harry Leib 《International Journal of Communications, Network and System Sciences》 2016年第10期387-412,共26页
This paper proposes a wavelet based receiver structure for frequency-flat time-varying Rayleigh channels, consisting of a receiver front-end followed by a Maximum A-Posteriori (MAP) detector. Discretization of the rec... This paper proposes a wavelet based receiver structure for frequency-flat time-varying Rayleigh channels, consisting of a receiver front-end followed by a Maximum A-Posteriori (MAP) detector. Discretization of the received continuous time signal using filter banks is an essential stage in the front-end part, where the Fast Haar Transform (FHT) is used to reduce complexity. Analysis of our receiver over slow-fading channels shows that it is optimal for certain modulation schemes. By comparison with literature, it is shown that over such channels our receiver can achieve optimal performance for Time-Orthogonal modulation. Computed and Monte-Carlo simulated performance results over fast time-varying Rayleigh fading channels show that with Minimum Shift Keying (MSK), our receiver using four basis functions (filters) lowers the error floor by more than one order of magnitude with respect to other techniques of comparable complexity. Orthogonal Frequency Shift Keying (FSK) can achieve the same performance as Time-Orthogonal modulation for the slow-fading case, but suffers some degradation over fast-fading channels where it exhibits an error floor. Compared to MSK, however, Orthogonal FSK provides better performance. 展开更多
关键词 Receiver Structure time-varying Rayleigh channels Filter Banks Fast Haar Transform
下载PDF
基于盲超分辨的超大规模MIMO-OFDM信道与感知参数联合估计
14
作者 褚宏云 李旭旭 +1 位作者 潘雪 李莹华 《移动通信》 2024年第4期81-85,104,共6页
面向未来6G网络,ISAC与XL-MIMO技术有机结合、共同演进,有望进一步提升ISAC性能。然而,XL-MIMO-ISAC中部署大量天线会产生近场效应,为准确获取CSI和目标参数信息带来关键挑战。为此,采用线性修改的原子范数最小化方法,建模毫米波通信信... 面向未来6G网络,ISAC与XL-MIMO技术有机结合、共同演进,有望进一步提升ISAC性能。然而,XL-MIMO-ISAC中部署大量天线会产生近场效应,为准确获取CSI和目标参数信息带来关键挑战。为此,采用线性修改的原子范数最小化方法,建模毫米波通信信道和感知阵列响应这两种盲源之间极坐标域的子空间一致关联,并提出了一种基于盲超分辨技术的CSI与感知参数并行估计方案,以避免从叠加信号中串行估计通信信道与目标参数信息造成误差传播。将联合盲源估计建模为非完全观测条件下的低秩矩阵重构问题,并引入PSWF将问题转化为SDP。仿真结果验证了提出的算法在CSI精度和目标参数分辨率方面的有效性。 展开更多
关键词 通信感知一体化 线性修改的原子范数 近场信道与感知参数估计 椭球体波函数 盲超分辨
下载PDF
Channel Estimation for Reconfigurable Intelligent Surface Assisted Wireless Communication Systems in Mobility Scenarios 被引量:10
15
作者 Zhendong Mao Mugen Peng Xiqing Liu 《China Communications》 SCIE CSCD 2021年第3期29-38,共10页
Reconfigurable intelligent surface(RIS)can manipulate the wireless propagation environment by smartly adjusting the amplitude/phase in a programmable panel,enjoying the improved performance.The accurate acquisition of... Reconfigurable intelligent surface(RIS)can manipulate the wireless propagation environment by smartly adjusting the amplitude/phase in a programmable panel,enjoying the improved performance.The accurate acquisition of the instantaneous channel state information(CSI)in the cascaded RIS chain makes an indispensable contribution to the performance gains.However,it is quite challenging to estimate the CSI in a time-variant scenario due to the limited signal processing capability of the passive elements embedded in a RIS pannel.In this work,a channel estimation scheme for the RIS-assisted wireless communication system is proposed,which is demonstrated to perform well in a time-variant scenario.The cascaded RIS channel is modeled as a state-space model based upon the mobility situations.In addition,to fully exploit the time correlation of channel,Kalman filter is employed by taking the prior information of channels into account.Further,the optimal reflection coefficients are derived according to the minimum mean square error(MMSE)criterion.Numerical results show that the proposed methods exhibit superior performance if compared with a conventional channel estimation scheme. 展开更多
关键词 reconfigurable intelligent surface(RIS) channel estimation time-variant channel kalman filter
下载PDF
A Fuzzy Clustering Algorithm Based on Multipath Component Trajectory for Millimeter Wave Radio Channels
16
作者 Fei Du Yu Zhang +5 位作者 Qingliang Li Xinyue Zhang Bo Zhu Zihao Fu Suiyan Geng Xiongwen Zhao 《China Communications》 SCIE CSCD 2022年第11期99-111,共13页
Time-varying channel modeling plays an important role for many applications in time-variant scenarios,while most clustering algorithms focus on static channels and cannot accurately model the channel time-evolution pr... Time-varying channel modeling plays an important role for many applications in time-variant scenarios,while most clustering algorithms focus on static channels and cannot accurately model the channel time-evolution properties.In this paper,a fuzzy clustering algorithm based on multipath component(MPC)trajectory is proposed.Firstly,both the distance and velocity similarities of the MPCs in different snapshots are taken into account to track the MPC trajectory,in which the fuzzy scheme and a kernel function are used to calculate the distance and velocity similarities,respectively.Secondly,a fuzzy MPC trajectory clustering algorithm is proposed to cluster the MPCs in multiple snapshots.The MPCs in a snapshot are clustered according to the membership,which is defined as the probability that a MPC belongs to different clusters.Finally,time-varying channels at 28 GHz are simulated to validate the performance of our proposed algorithm.The results show that our proposed algorithm is able to accurately identify the clusters in time-varying channels compared with the existing clustering algorithms. 展开更多
关键词 channel modeling time-varying clustering multiple path component MPC trajectory 6G
下载PDF
Stochastic Modeling and Power Control of Time-Varying Wireless Communication Networks
17
作者 Mohammed M. Olama Seddik M. Djouadi Charalambos D. Charalambous 《Communications and Network》 2014年第3期155-164,共10页
Wireless networks are characterized by nodes mobility, which makes the propagation environment time-varying and subject to fading. As a consequence, the statistical characteristics of the received signal vary continuo... Wireless networks are characterized by nodes mobility, which makes the propagation environment time-varying and subject to fading. As a consequence, the statistical characteristics of the received signal vary continuously, giving rise to a Doppler power spectral density (DPSD) that varies from one observation instant to the next. This paper is concerned with dynamical modeling of time-varying wireless fading channels, their estimation and parameter identification, and optimal power control from received signal measurement data. The wireless channel is characterized using a stochastic state-space form and derived by approximating the time-varying DPSD of the channel. The expected maximization and Kalman filter are employed to recursively identify and estimate the channel parameters and states, respectively, from online received signal strength measured data. Moreover, we investigate a centralized optimal power control algorithm based on predictable strategies and employing the estimated channel parameters and states. The proposed models together with the estimation and power control algorithms are tested using experimental measurement data and the results are presented. 展开更多
关键词 WIRELESS Networks time-varying WIRELESS Fading channel Impulse Response Doppler POWER Spectral Density STOCHASTIC STATE-SPACE Model STOCHASTIC Modeling Optimal POWER Control EXPECTATION Maximization Kalman Filter
下载PDF
水声FBMC-OQAM通信的时变信道估计与符号检测
18
作者 陆雪松 江雨林 +3 位作者 李静萱 魏艳 涂星滨 瞿逢重 《哈尔滨工程大学学报(英文版)》 CSCD 2023年第3期636-649,共14页
Filter bank multicarrier(FBMC)systems with offset quadrature amplitude modulation(OQAM)need long data blocks to achieve high spectral efficiency.However,the transmission of long data blocks in underwater acoustic(UWA)... Filter bank multicarrier(FBMC)systems with offset quadrature amplitude modulation(OQAM)need long data blocks to achieve high spectral efficiency.However,the transmission of long data blocks in underwater acoustic(UWA)communication systems often encounters the challenge of time-varying channels.This paper proposes a time-varying channel tracking method for short-range high-rate UWA FBMC-OQAM communication applications.First,a known preamble is used to initialize the channel estimation at the initial time of the signal block.Next,the estimated channel is applied to detect data symbols at several symbol periods.The detected data symbols are then reused as new pilots to estimate the next time channel.In the above steps,the unified transmission matrix model is extended to describe the time-varying channel input-output model in this paper and is used for symbol detection.Simulation results show that the channel tracking error can be reduced to less than−20 dB when the channel temporal coherence coefficient exceeds 0.75 within one block period of FBMC-OQAM signals.Compared with conventional known-pilot-based methods,the proposed method needs lower system overhead while exhibiting similar time-varying channel tracking performance.The sea trial results further proved the practicability of the proposed method. 展开更多
关键词 FBMC-OQAM Underwater acoustic communications channel estimation time-varying channel Data reuse Iterative estimation
下载PDF
河渠水位线性变化条件下河渠-潜水非稳定流模型及其解 被引量:5
19
作者 吴丹 陶月赞 林飞 《应用数学和力学》 CSCD 北大核心 2018年第9期1043-1050,共8页
在河渠水位迅速变化后再缓慢变化的条件下,建立了河渠半无限潜水含水层中非稳定渗流模型.利用Boussinesq第一线性化方法及Laplace变换,并注意应用Laplace变换中的"积分性质",给出形式相对简单、由常用函数表达的解,阐述特定... 在河渠水位迅速变化后再缓慢变化的条件下,建立了河渠半无限潜水含水层中非稳定渗流模型.利用Boussinesq第一线性化方法及Laplace变换,并注意应用Laplace变换中的"积分性质",给出形式相对简单、由常用函数表达的解,阐述特定解及其相应的物理意义.由解所揭示的潜水位变化规律表明,含水层任一点处潜水位变动速度的时间变化曲线形态是固定的,与河渠边界水位变动速率λ无关;潜水最大变速发生的时间,随λ呈非线性位移.依据潜水位变化规律,建立利用潜水位变动速度求含水层参数的方法,并用实例演示了拐点法求参数的过程. 展开更多
关键词 潜水非稳定流 河渠边界 水位线性变化 LAPLACE变换 积分性质
下载PDF
线性时变信道模型下的OFDM性能及误差分析 被引量:1
20
作者 解永生 汪明亮 +1 位作者 周磊磊 付耀先 《南京邮电大学学报(自然科学版)》 北大核心 2013年第2期42-48,共7页
当归一化多普勒频移小于0.1时,信道的时变性是近似线性变化的。文中研究了线性时变信道下OFDM系统的ICI干扰,并分析了线性时变信道模型的系统误差。分析表明,采用线性模型对信道建模时,系统存在建模误差和近似计算误差,同时信道平均建... 当归一化多普勒频移小于0.1时,信道的时变性是近似线性变化的。文中研究了线性时变信道下OFDM系统的ICI干扰,并分析了线性时变信道模型的系统误差。分析表明,采用线性模型对信道建模时,系统存在建模误差和近似计算误差,同时信道平均建模误差比计算误差大了约7 dB。 展开更多
关键词 正交频分复用 子载波间干扰 线性时变信道 建模误差 计算误差
下载PDF
上一页 1 2 下一页 到第
使用帮助 返回顶部