In wideband noncooperative interference cancellation,the reference signals obtained through auxiliary antennas are weighted to cancel with the interference signal.The correlation between the reference signal and the i...In wideband noncooperative interference cancellation,the reference signals obtained through auxiliary antennas are weighted to cancel with the interference signal.The correlation between the reference signal and the interference signal determines interference cancellation performance,while the auxiliary antenna array affects the correlation by influencing the amplitude and phase of the reference signals.This paper analyzes the effect of auxiliary antenna array on multiple performances of wideband noncooperative interference cancellation.Firstly,the array received signal model of wideband interference is established,and the weight vector coupled with the auxiliary antennas array manifold is solved by spectral analysis and eigen-subspace decomposition.Then,multiple performances which include cancellation resolution,grating null,wideband interference cancellation ratio(ICR),and convergence rate are quantitatively characterized with the auxiliary antenna array.It is obtained through analysis that the performances mutually restrict the auxiliary antenna array.Higher cancellation resolution requires larger array aperture,but when the number of auxiliary antennas is fixed,larger array aperture results in more grating nulls.When the auxiliary antennas are closer to the main antenna,the wideband ICR is improved,but the convergence rate is reduced.The conclusions are verified through simulation of one-dimensional uniform array and two-dimensional nonuniform array.The experiments of three arrays are compared,and the results conform well with simulation and support the theoretical analysis.展开更多
To mitigate the effects of the previous symbol decision errors of a decision-feedback （DF） equalizer on the current decision, a particle filter （PF） based DF equalizer for frequency selective multiple-input-multip...To mitigate the effects of the previous symbol decision errors of a decision-feedback （DF） equalizer on the current decision, a particle filter （PF） based DF equalizer for frequency selective multiple-input-multiple-output （MIMO） channel is proposed. On the basis of the analyses of DF equalization for the MIMO wireless system, it is found that a stochastic interference cancellation （IC） scheme can be employed to prevent the error propagation in a severe space-time interference scenario. This is because the random rather than the deterministic scheme can reduce the probability of an error decision even if an error decision occurs. Besides, the signal-to-interference-plus-noise ratio （SINR） based IC order, which is obtained via pilot, can guarantee the optimality of the cancellation. The bit error rate （BER） performance of the proposed scheme is verified through simulation experiments under different multipath interference environment.展开更多
Based on a dual-polarization high-frequency wave radar system, an adaptive system using horizontal antennas for the suppression of the Es layer interference （ELI） is deseribech The data received from the horizontal ...Based on a dual-polarization high-frequency wave radar system, an adaptive system using horizontal antennas for the suppression of the Es layer interference （ELI） is deseribech The data received from the horizontal antennas were correlated with the data received from the Vertically Polarized Antennas （VPAs） to estimate and cancel the interference adaptively in the VPAs. Suppressing the interference after each coherent integration time interval, about 25 dB signal-to-interference ratio is expected with the experimentally derived data.展开更多
Many properties of frequency-hopped spread-spectrum multiple access （FH/SSMA）, such as, robustness against frequency selective fading and jamming make it a preferred multiple access communication scheme. But cochann...Many properties of frequency-hopped spread-spectrum multiple access （FH/SSMA）, such as, robustness against frequency selective fading and jamming make it a preferred multiple access communication scheme. But cochannel interference （CCI） can seriously harm the system＇s performance. On the basis of the analysis of the CCI pattern of frequency hopped multiple access signal, a new multiuser detection algorithm for canceling the CCI in frequency hopped multiple access systems is proposed. In the proposed scheme, the CCI is canceled by first detecting the frequency hopping slot, and then classifying and regenerating the candidates of the interference pattern from the time-frequency matrix. Both the theoretical analysis and computer simulation results show that compared to the conventional detector and Mabuchi＇s detector, this new multiuser detector has lower complexity, better convergence stability, and is suitable for both additive white Gaussian noise （AWGN） channels and Rayleigh fading channels.展开更多
With the development of micro-satellite technology,traditional monolithic satellites can be replaced by micro-satellite clusters to achieve high flexibility and dynamic reconfiguration capability.For satellite cluster...With the development of micro-satellite technology,traditional monolithic satellites can be replaced by micro-satellite clusters to achieve high flexibility and dynamic reconfiguration capability.For satellite clusters based on the frequency division-code division multiple access(FD-CDMA)communication system,the inter-satellite ranging precision is usually constrained due to the influence ofmulti-address interference(MAI).Themulti-user detection(MUD)is a solution to MAI,which can be divided into two categories:the linear detector(LD)and the non-linear detector(NLD).The general idea of the LD is aiming to make a better decision during the symbol decision process by using the information of all channels.However,it is not beneficial for the signal phase tracking precision.Instead,the principle of the NLD is to rebuild the interference signal and cancel it from the original one,which can improve the ranging performance at the expense of considerable delays.In order to enable simultaneous ranging and communication and reduce multi-node ranging performance degradation,this paper proposes an NLD scheme based on a delay locked loop(DLL),which simplifies the receiver structure and introduces no delay in the decision process.This scheme utilizes the information obtained from the interference channel to reconstruct the interference signal and then cancels it from the original delayed signal.Therefore,the DLL input signal-to-interference ratio(SIR)of the desired channel can be significantly improved.The experimental results show that with the proposed scheme,the standard deviation of the tracking steady error is decreased from 5.59 cm to 3.97 cm for SIR=5 dB,and 13.53 cm to 5.77 cm for SIR=-5 dB,respectively.展开更多
Recent research shows that it is possible to achieve the full-duplex system by cancelling strong self-interference signals, which can be divided into three classes respectively, i.e., passive cancellation, active canc...Recent research shows that it is possible to achieve the full-duplex system by cancelling strong self-interference signals, which can be divided into three classes respectively, i.e., passive cancellation, active cancellation and digital cancellation. This pa- per tries to achieve the full-duplex system without using active cancellation, thus a full-duplex system using a joint mechanism based on a novel passive cancellation method and a novel digital cancellation method is proposed. Therein, a good antenna place- ment guided by the theory of the antenna electromagnetic field for the passive cancellation is presented. For the proposed digital can- cellation method, unlike previous separate mechanisms, it is de- signed by using the recursive least square （RLS） algorithm jointly with passive cancellation. The self-interference channel state in- formation （CSI） is transferred as the input of digital cancellation to balance the performance and the complexity. Experimental results show that the proposed self-interference cancellation mechanism can achieve about 85 dB which is better than the previous re- search. Meanwhile, this design provides a better performance compared with half-duplex with both line-of-sight channel and non- line-of-sight channel.展开更多
本文研究了基于1-比特模数转换器(Analog to Digital Converters,ADCs)的大规模多输入多输出(Multiple Input Multiple Output,MIMO)系统上行链路的多用户频率同步问题,其中多个单天线用户与配置大规模天线阵列的基站采用正交频分复用(O...本文研究了基于1-比特模数转换器(Analog to Digital Converters,ADCs)的大规模多输入多输出(Multiple Input Multiple Output,MIMO)系统上行链路的多用户频率同步问题,其中多个单天线用户与配置大规模天线阵列的基站采用正交频分复用(Orthogonal Frequency Division Multiplexing,OFDM)技术进行通信.针对多用户角度不重叠的场景,本文利用接收波束成形网络进行多用户干扰消除,从混叠的多用户信号中提取出目标用户的信息,进而对载波频偏(Carrier Frequency Offset,CFO)进行估计.其次,考虑1-比特ADC导致的量化噪声对系统性能的影响,理论推导了基站接收端处的信噪比(Signal-Noise Ratio,SNR).为了提升系统的性能,基于理论SNR对波束成形网络进行了优化设计.最后,计算机仿真结果显示了所提出的频偏估计算法与其他现有算法相比具有更好的性能.展开更多
低轨卫星通信凭借低传输时延和组网灵活等优势,正成为新一代卫星通信的关键技术。广义频分复用(Generalized Frequency Division Multiplexing,GFDM)作为候选波形,能够满足低轨卫星通信各种应用场景需求。在基于GFDM的低轨卫星通信系统...低轨卫星通信凭借低传输时延和组网灵活等优势,正成为新一代卫星通信的关键技术。广义频分复用(Generalized Frequency Division Multiplexing,GFDM)作为候选波形,能够满足低轨卫星通信各种应用场景需求。在基于GFDM的低轨卫星通信系统中,由于GFDM子载波间非正交特性以及低轨卫星信道存在时间-频率双选择性,导致数据符号受到严重的子载波间干扰和子符号间干扰,传统信道估计算法难以实现可靠的数据传输。现有的基于离散导频的迭代信道估计和信号检测算法(Iterative Channel Estimation and Signal Detection Algorithm Based on Discrete Pilots,ICESD-DP)虽然提高了在双选信道下信道估计的准确性,但需要付出高昂的计算成本。为解决上述问题,提出了一种基于判决重构符号的迭代信道估计和干扰消除算法(Iterative Channel Estimation and Interference Cancellation Algorithm Based on Judgment Reconstructed Symbols,ICEIC-JRS),使用经过干扰预处理的导频进行初始信道估计和均衡,在每次迭代中利用Turbo译码器生成的判决重构符号估计数据符号的有效增益和干扰增益,继而对接收符号进行干扰消除,以提高信道估计与符号检测的精度。仿真结果表明,与ICESD-DP相比,ICEIC-JRS在较多迭代次数下表现出更优异的误码率(Bit Error Rate,BER)和均方误差(Mean Square Error,MSE)性能,且ICEIC-JRS的单次迭代复杂度下降了一个数量级,更适用于对运算复杂度有较高要求的低轨卫星通信系统。展开更多
基金supported by the National Fund for Distinguished Young Scholars(52025072)the National Natural Science Foundation of China(52177012)the Foundation of National Key Laboratory of Science and Technology(614221722051301).
文摘In wideband noncooperative interference cancellation,the reference signals obtained through auxiliary antennas are weighted to cancel with the interference signal.The correlation between the reference signal and the interference signal determines interference cancellation performance,while the auxiliary antenna array affects the correlation by influencing the amplitude and phase of the reference signals.This paper analyzes the effect of auxiliary antenna array on multiple performances of wideband noncooperative interference cancellation.Firstly,the array received signal model of wideband interference is established,and the weight vector coupled with the auxiliary antennas array manifold is solved by spectral analysis and eigen-subspace decomposition.Then,multiple performances which include cancellation resolution,grating null,wideband interference cancellation ratio(ICR),and convergence rate are quantitatively characterized with the auxiliary antenna array.It is obtained through analysis that the performances mutually restrict the auxiliary antenna array.Higher cancellation resolution requires larger array aperture,but when the number of auxiliary antennas is fixed,larger array aperture results in more grating nulls.When the auxiliary antennas are closer to the main antenna,the wideband ICR is improved,but the convergence rate is reduced.The conclusions are verified through simulation of one-dimensional uniform array and two-dimensional nonuniform array.The experiments of three arrays are compared,and the results conform well with simulation and support the theoretical analysis.
基金supported in part by the National Natural Science Foundation of China (60672047)the Shanghai Postdoctoral Scientific Program (05R214110).
文摘To mitigate the effects of the previous symbol decision errors of a decision-feedback （DF） equalizer on the current decision, a particle filter （PF） based DF equalizer for frequency selective multiple-input-multiple-output （MIMO） channel is proposed. On the basis of the analyses of DF equalization for the MIMO wireless system, it is found that a stochastic interference cancellation （IC） scheme can be employed to prevent the error propagation in a severe space-time interference scenario. This is because the random rather than the deterministic scheme can reduce the probability of an error decision even if an error decision occurs. Besides, the signal-to-interference-plus-noise ratio （SINR） based IC order, which is obtained via pilot, can guarantee the optimality of the cancellation. The bit error rate （BER） performance of the proposed scheme is verified through simulation experiments under different multipath interference environment.
文摘Based on a dual-polarization high-frequency wave radar system, an adaptive system using horizontal antennas for the suppression of the Es layer interference （ELI） is deseribech The data received from the horizontal antennas were correlated with the data received from the Vertically Polarized Antennas （VPAs） to estimate and cancel the interference adaptively in the VPAs. Suppressing the interference after each coherent integration time interval, about 25 dB signal-to-interference ratio is expected with the experimentally derived data.
基金the National Natural Science Foundation of China (60372055)National Doctoral Foundation of China (20030698027).
文摘Many properties of frequency-hopped spread-spectrum multiple access （FH/SSMA）, such as, robustness against frequency selective fading and jamming make it a preferred multiple access communication scheme. But cochannel interference （CCI） can seriously harm the system＇s performance. On the basis of the analysis of the CCI pattern of frequency hopped multiple access signal, a new multiuser detection algorithm for canceling the CCI in frequency hopped multiple access systems is proposed. In the proposed scheme, the CCI is canceled by first detecting the frequency hopping slot, and then classifying and regenerating the candidates of the interference pattern from the time-frequency matrix. Both the theoretical analysis and computer simulation results show that compared to the conventional detector and Mabuchi＇s detector, this new multiuser detector has lower complexity, better convergence stability, and is suitable for both additive white Gaussian noise （AWGN） channels and Rayleigh fading channels.
基金supported by the China National Funds of Distributed Young Scientists(61525403)the Fundamental Research Funds for the Central Universities(2018QNA4053)
文摘With the development of micro-satellite technology,traditional monolithic satellites can be replaced by micro-satellite clusters to achieve high flexibility and dynamic reconfiguration capability.For satellite clusters based on the frequency division-code division multiple access(FD-CDMA)communication system,the inter-satellite ranging precision is usually constrained due to the influence ofmulti-address interference(MAI).Themulti-user detection(MUD)is a solution to MAI,which can be divided into two categories:the linear detector(LD)and the non-linear detector(NLD).The general idea of the LD is aiming to make a better decision during the symbol decision process by using the information of all channels.However,it is not beneficial for the signal phase tracking precision.Instead,the principle of the NLD is to rebuild the interference signal and cancel it from the original one,which can improve the ranging performance at the expense of considerable delays.In order to enable simultaneous ranging and communication and reduce multi-node ranging performance degradation,this paper proposes an NLD scheme based on a delay locked loop(DLL),which simplifies the receiver structure and introduces no delay in the decision process.This scheme utilizes the information obtained from the interference channel to reconstruct the interference signal and then cancels it from the original delayed signal.Therefore,the DLL input signal-to-interference ratio(SIR)of the desired channel can be significantly improved.The experimental results show that with the proposed scheme,the standard deviation of the tracking steady error is decreased from 5.59 cm to 3.97 cm for SIR=5 dB,and 13.53 cm to 5.77 cm for SIR=-5 dB,respectively.
基金supported by the National Natural Science Foundation of China(601720456103200661271282)
文摘Recent research shows that it is possible to achieve the full-duplex system by cancelling strong self-interference signals, which can be divided into three classes respectively, i.e., passive cancellation, active cancellation and digital cancellation. This pa- per tries to achieve the full-duplex system without using active cancellation, thus a full-duplex system using a joint mechanism based on a novel passive cancellation method and a novel digital cancellation method is proposed. Therein, a good antenna place- ment guided by the theory of the antenna electromagnetic field for the passive cancellation is presented. For the proposed digital can- cellation method, unlike previous separate mechanisms, it is de- signed by using the recursive least square （RLS） algorithm jointly with passive cancellation. The self-interference channel state in- formation （CSI） is transferred as the input of digital cancellation to balance the performance and the complexity. Experimental results show that the proposed self-interference cancellation mechanism can achieve about 85 dB which is better than the previous re- search. Meanwhile, this design provides a better performance compared with half-duplex with both line-of-sight channel and non- line-of-sight channel.
文摘本文研究了基于1-比特模数转换器(Analog to Digital Converters,ADCs)的大规模多输入多输出(Multiple Input Multiple Output,MIMO)系统上行链路的多用户频率同步问题,其中多个单天线用户与配置大规模天线阵列的基站采用正交频分复用(Orthogonal Frequency Division Multiplexing,OFDM)技术进行通信.针对多用户角度不重叠的场景,本文利用接收波束成形网络进行多用户干扰消除,从混叠的多用户信号中提取出目标用户的信息,进而对载波频偏(Carrier Frequency Offset,CFO)进行估计.其次,考虑1-比特ADC导致的量化噪声对系统性能的影响,理论推导了基站接收端处的信噪比(Signal-Noise Ratio,SNR).为了提升系统的性能,基于理论SNR对波束成形网络进行了优化设计.最后,计算机仿真结果显示了所提出的频偏估计算法与其他现有算法相比具有更好的性能.
文摘低轨卫星通信凭借低传输时延和组网灵活等优势,正成为新一代卫星通信的关键技术。广义频分复用(Generalized Frequency Division Multiplexing,GFDM)作为候选波形,能够满足低轨卫星通信各种应用场景需求。在基于GFDM的低轨卫星通信系统中,由于GFDM子载波间非正交特性以及低轨卫星信道存在时间-频率双选择性,导致数据符号受到严重的子载波间干扰和子符号间干扰,传统信道估计算法难以实现可靠的数据传输。现有的基于离散导频的迭代信道估计和信号检测算法(Iterative Channel Estimation and Signal Detection Algorithm Based on Discrete Pilots,ICESD-DP)虽然提高了在双选信道下信道估计的准确性,但需要付出高昂的计算成本。为解决上述问题,提出了一种基于判决重构符号的迭代信道估计和干扰消除算法(Iterative Channel Estimation and Interference Cancellation Algorithm Based on Judgment Reconstructed Symbols,ICEIC-JRS),使用经过干扰预处理的导频进行初始信道估计和均衡,在每次迭代中利用Turbo译码器生成的判决重构符号估计数据符号的有效增益和干扰增益,继而对接收符号进行干扰消除,以提高信道估计与符号检测的精度。仿真结果表明,与ICESD-DP相比,ICEIC-JRS在较多迭代次数下表现出更优异的误码率(Bit Error Rate,BER)和均方误差(Mean Square Error,MSE)性能,且ICEIC-JRS的单次迭代复杂度下降了一个数量级,更适用于对运算复杂度有较高要求的低轨卫星通信系统。
