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
针对基于RSSI和CSI的指纹定位技术易受环境干扰、定位精度较低的问题,提出了一种基于RSSI指纹和相位修正信道状态信息(phase correct based channel state information,PC-CSI)指纹的加权融合指纹定位技术。基于PC-CSI的指纹定位在传统...针对基于RSSI和CSI的指纹定位技术易受环境干扰、定位精度较低的问题,提出了一种基于RSSI指纹和相位修正信道状态信息(phase correct based channel state information,PC-CSI)指纹的加权融合指纹定位技术。基于PC-CSI的指纹定位在传统基于CSI幅值的指纹定位基础上增加相位信息对定位结果进行修正,之后对RSSI指纹和PC-CSI指纹的定位结果加权重定位。实验结果表明,提出的加权融合指纹定位算法与基于CSI的主动定位算法相比,平均定位误差(mean position error,MPE)降低了36.2%,能满足室内定位需求。展开更多
Spread Spectrum (SS) is a promising technique to resist interference in wireless communication system. In order to further improve this capability, this paper proposes a Hybrid Carrier (HC) SS system, combining 4-Weig...Spread Spectrum (SS) is a promising technique to resist interference in wireless communication system. In order to further improve this capability, this paper proposes a Hybrid Carrier (HC) SS system, combining 4-Weighted Fractional Fourier Transform (4-WFRFT) with SS technique. In this HC-SS system, due to the property of 4-WFRFT, the signal energy of proposed system is distributed on the time-frequency plane more evenly and symmetrically, compared with the existing Single-Carrier (SC) and Multi-Carrier (MC) spread spectrum systems. In the selective channel, the proposed method can split the interference to a more broad range in order to reduce the influence, resulting in the better system performance. In addition, proposed system can be seen as the convergence of the existing SS techniques, which is a main feature in future.展开更多
Inter-regional transmission line fault often results in power flow transferring, tie-line overloading and system islanding. Traditional control methods such asgenerator tripping and load shedding are costly, and also ...Inter-regional transmission line fault often results in power flow transferring, tie-line overloading and system islanding. Traditional control methods such asgenerator tripping and load shedding are costly, and also have undesirable impacts on theloadside. In this paper, a new emergency power control strategy is proposed for multi-channel interconnected system by using the overload capacity of non-fault DC lines. First of all, the capacity of emergency power control can be acquired by critical transmission power of a certain tie-line for stability. Secondly, the shortest electric distance can be calculated by Dijkstra algorithm, and then the priority of emergency control of the DC lines can be obtained by the entropy weight method. When the inter-regional transmission power decreases and the effect of single DC line emergency control is poor, the multi-channel cooperative emergency control strategy is proposed to ensure the system stability. Simulation results verify the effectiveness of the method proposed.展开更多
The paper deals with two-dimensional (2D) channel estimation of Orthogonal Frequency Division Multiplexing (OFDM) system in slow fading wireless channel. We concentrate on two channel estimation schemes: Least Square ...The paper deals with two-dimensional (2D) channel estimation of Orthogonal Frequency Division Multiplexing (OFDM) system in slow fading wireless channel. We concentrate on two channel estimation schemes: Least Square (LS)+Weighted BiLinear (WBL) and LS+Linear Minimum Mean-Squared Error (LMMSE) where the first method is proposed in this paper. After theory analysis and simulation in Typical Urban (TU) channel, we find that LS+LMMSE achieves the optimal perform-ance by exploiting prior knowledge of channel whereas LS+WBL, without requiring channel knowl-edge and with only half of the computational amount of LS+LMMSE, approaches LS+LMMSE in Bit Error Ratio (BER) performance when the distance of two adjoining pilot symbols along frequency di-rection is sufficiently small. This makes LS+WBL very suitable for wideband wireless applications.展开更多
A novel method,referred to as joint multiple subpulses processing,is developed to calibrate the nonideal transfer function of radio frequency front-end and I/Q imbalance in quadrature modulate/demodulate systems simul...A novel method,referred to as joint multiple subpulses processing,is developed to calibrate the nonideal transfer function of radio frequency front-end and I/Q imbalance in quadrature modulate/demodulate systems simultaneously,which frequently occur in wideband Synthetic Aperture Radar(SAR) systems.Based on the time-frequency relation of the chirp signal and the analyses of the channel errors in wideband SAR,joint multiple subpulses processing method is adopted to separate the image frequency component due to the I/Q channel error.Then,the complete description of the channel error is acquired for building the correction function,which is used to correct the radar raw echo in frequency domain.The validity and capability of this method are demonstrated by the experiments of the channel error correction on the high resolution SAR system with the effective bandwidth of 500 MHz.展开更多
针对齿轮箱单一传感器故障识别精度波动大、数据利用率低、可靠性低及故障诊断模型在多工况下泛化能力不足等问题,提出了一种加权融合多通道数据与深度迁移模型的齿轮箱故障诊断方法。首先,为了充分挖掘齿轮箱多通道数据的信息,提出了...针对齿轮箱单一传感器故障识别精度波动大、数据利用率低、可靠性低及故障诊断模型在多工况下泛化能力不足等问题,提出了一种加权融合多通道数据与深度迁移模型的齿轮箱故障诊断方法。首先,为了充分挖掘齿轮箱多通道数据的信息,提出了基于信息熵加权的多通道融合方法,采用信息熵法计算各通道数据的融合权重,并对各通道的采样数据进行加权融合。其次,利用源域的融合数据对深度迁移模型进行预训练,将预训练得到的模型参数作为目标域模型的初始化参数,同时冻结目标域模型特征提取器的参数,并利用目标域的融合数据对目标域模型分类器的参数进行微调,实现深度迁移模型从源域到目标域的迁移以适应新的目标样本识别任务。最后,齿轮箱多工况迁移诊断试验结果表明,所提方法可有效用于齿轮箱的故障诊断,相比传统迁移学习方法平衡分布自适应算法(balanced distribution adaptation,BDA)、迁移成分分析(transfer component analysis,TCA)、联合分布自适应算法(joint distribution adaptation,JDA)、统计分布和几何空间联合调整算法(joint geometric and statistical alignment,JGSA)、测地线流式核算法(geodesic flow kernel,GFK)及深度迁移学习方法自适应批归一化(adaptive batch normalization,AdaBN)、多核最大均值差异(multi-kernel maximum mean discrepancy,MK-MMD)、深度卷积迁移学习网络(deep convolutional transfer learning network,DCTLN)这8种当前常用方法,具有更高的平均迁移诊断精度和变工况下良好的泛化性能。展开更多
This work proposes an improved inertia weight update method and position update method in Particle Swarm Optimization (PSO) to enhance the convergence and mean square error of channel equalizer. The search abilities o...This work proposes an improved inertia weight update method and position update method in Particle Swarm Optimization (PSO) to enhance the convergence and mean square error of channel equalizer. The search abilities of PSO are managed by the key parameter Inertia Weight (IW). A higher value leads to global search whereas a smaller value shifts the search to local which makes convergence faster. Different approaches are reported in literature to improve PSO by modifying inertia weight. This work investigates the performance of the existing PSO variants related to time varying inertia weight methods and proposes new strategies to improve the convergence and mean square error of channel equalizer. Also the position update method in PSO is modified to achieve better convergence in channel equalization. The simulation presents the enhanced performance of the proposed techniques in transversal and decision feedback models. The simulation results also analyze the superiority in linear and nonlinear channel conditions.展开更多
基金supported by the National Natural Science Foundation of China (Nos. 61801461, 61801460)the Strategical Leadership Project of Chinese Academy of Sciences (grant No. XDC02070800)the Shanghai Municipality of Science and Technology Commission Project (Nos. 18XD1404100, 17QA1403800)
文摘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.
文摘针对基于RSSI和CSI的指纹定位技术易受环境干扰、定位精度较低的问题,提出了一种基于RSSI指纹和相位修正信道状态信息(phase correct based channel state information,PC-CSI)指纹的加权融合指纹定位技术。基于PC-CSI的指纹定位在传统基于CSI幅值的指纹定位基础上增加相位信息对定位结果进行修正,之后对RSSI指纹和PC-CSI指纹的定位结果加权重定位。实验结果表明,提出的加权融合指纹定位算法与基于CSI的主动定位算法相比,平均定位误差(mean position error,MPE)降低了36.2%,能满足室内定位需求。
基金Acknowledgements The authors would like to thank the reviewers whose comments have helped them to improve the technical quality and the presentation of the manuscript. This work was supported by the National Natural Science Foundation of China under Grant No. 61171110.
文摘Spread Spectrum (SS) is a promising technique to resist interference in wireless communication system. In order to further improve this capability, this paper proposes a Hybrid Carrier (HC) SS system, combining 4-Weighted Fractional Fourier Transform (4-WFRFT) with SS technique. In this HC-SS system, due to the property of 4-WFRFT, the signal energy of proposed system is distributed on the time-frequency plane more evenly and symmetrically, compared with the existing Single-Carrier (SC) and Multi-Carrier (MC) spread spectrum systems. In the selective channel, the proposed method can split the interference to a more broad range in order to reduce the influence, resulting in the better system performance. In addition, proposed system can be seen as the convergence of the existing SS techniques, which is a main feature in future.
文摘Inter-regional transmission line fault often results in power flow transferring, tie-line overloading and system islanding. Traditional control methods such asgenerator tripping and load shedding are costly, and also have undesirable impacts on theloadside. In this paper, a new emergency power control strategy is proposed for multi-channel interconnected system by using the overload capacity of non-fault DC lines. First of all, the capacity of emergency power control can be acquired by critical transmission power of a certain tie-line for stability. Secondly, the shortest electric distance can be calculated by Dijkstra algorithm, and then the priority of emergency control of the DC lines can be obtained by the entropy weight method. When the inter-regional transmission power decreases and the effect of single DC line emergency control is poor, the multi-channel cooperative emergency control strategy is proposed to ensure the system stability. Simulation results verify the effectiveness of the method proposed.
基金Supported by the National Natural Science Foundation of China (No: 60496311).
文摘The paper deals with two-dimensional (2D) channel estimation of Orthogonal Frequency Division Multiplexing (OFDM) system in slow fading wireless channel. We concentrate on two channel estimation schemes: Least Square (LS)+Weighted BiLinear (WBL) and LS+Linear Minimum Mean-Squared Error (LMMSE) where the first method is proposed in this paper. After theory analysis and simulation in Typical Urban (TU) channel, we find that LS+LMMSE achieves the optimal perform-ance by exploiting prior knowledge of channel whereas LS+WBL, without requiring channel knowl-edge and with only half of the computational amount of LS+LMMSE, approaches LS+LMMSE in Bit Error Ratio (BER) performance when the distance of two adjoining pilot symbols along frequency di-rection is sufficiently small. This makes LS+WBL very suitable for wideband wireless applications.
基金Supported by the National High-Tech Research and Development Plan of China(No.2007AA120302)
文摘A novel method,referred to as joint multiple subpulses processing,is developed to calibrate the nonideal transfer function of radio frequency front-end and I/Q imbalance in quadrature modulate/demodulate systems simultaneously,which frequently occur in wideband Synthetic Aperture Radar(SAR) systems.Based on the time-frequency relation of the chirp signal and the analyses of the channel errors in wideband SAR,joint multiple subpulses processing method is adopted to separate the image frequency component due to the I/Q channel error.Then,the complete description of the channel error is acquired for building the correction function,which is used to correct the radar raw echo in frequency domain.The validity and capability of this method are demonstrated by the experiments of the channel error correction on the high resolution SAR system with the effective bandwidth of 500 MHz.
文摘针对齿轮箱单一传感器故障识别精度波动大、数据利用率低、可靠性低及故障诊断模型在多工况下泛化能力不足等问题,提出了一种加权融合多通道数据与深度迁移模型的齿轮箱故障诊断方法。首先,为了充分挖掘齿轮箱多通道数据的信息,提出了基于信息熵加权的多通道融合方法,采用信息熵法计算各通道数据的融合权重,并对各通道的采样数据进行加权融合。其次,利用源域的融合数据对深度迁移模型进行预训练,将预训练得到的模型参数作为目标域模型的初始化参数,同时冻结目标域模型特征提取器的参数,并利用目标域的融合数据对目标域模型分类器的参数进行微调,实现深度迁移模型从源域到目标域的迁移以适应新的目标样本识别任务。最后,齿轮箱多工况迁移诊断试验结果表明,所提方法可有效用于齿轮箱的故障诊断,相比传统迁移学习方法平衡分布自适应算法(balanced distribution adaptation,BDA)、迁移成分分析(transfer component analysis,TCA)、联合分布自适应算法(joint distribution adaptation,JDA)、统计分布和几何空间联合调整算法(joint geometric and statistical alignment,JGSA)、测地线流式核算法(geodesic flow kernel,GFK)及深度迁移学习方法自适应批归一化(adaptive batch normalization,AdaBN)、多核最大均值差异(multi-kernel maximum mean discrepancy,MK-MMD)、深度卷积迁移学习网络(deep convolutional transfer learning network,DCTLN)这8种当前常用方法,具有更高的平均迁移诊断精度和变工况下良好的泛化性能。
文摘This work proposes an improved inertia weight update method and position update method in Particle Swarm Optimization (PSO) to enhance the convergence and mean square error of channel equalizer. The search abilities of PSO are managed by the key parameter Inertia Weight (IW). A higher value leads to global search whereas a smaller value shifts the search to local which makes convergence faster. Different approaches are reported in literature to improve PSO by modifying inertia weight. This work investigates the performance of the existing PSO variants related to time varying inertia weight methods and proposes new strategies to improve the convergence and mean square error of channel equalizer. Also the position update method in PSO is modified to achieve better convergence in channel equalization. The simulation presents the enhanced performance of the proposed techniques in transversal and decision feedback models. The simulation results also analyze the superiority in linear and nonlinear channel conditions.
