A cognitive radio transmitted reference ultra-wideband（CR-TR-UWB） system is proposed to improve the performance of TR-UWB systems with narrowband interference（NBI） from primary users（PU）.The transmitter of the C...A cognitive radio transmitted reference ultra-wideband（CR-TR-UWB） system is proposed to improve the performance of TR-UWB systems with narrowband interference（NBI） from primary users（PU）.The transmitter of the CR-TR-UWB system detects the band of PU,and then sends prolate spheroidal wave functions（PSWF） pulses with the same limited band as PU＇s to reduce interference with PU.The receiver uses a notch filter before autocorrelation to eliminate NBI from PU.The simulation results show that the bit error rate（BER） performance of the CR-TR-UWB system is close to that of TR-UWB systems without NBI when the system is interfered by single or double NBIs with a signal to interference ratio（SIR） of 0 dB,and if the signal to noise ratio（SNR） is 10 dB and the SIR varies from-20 to 10 dB,BER performance varies no more than an order of magnitude.The system has excellent resistance to NBI,strong robustness BER performance at different SNRs,and smaller interference with the same frequency band PU.展开更多
A generalized approach for narrowband interference （NBI） suppression in direct sequence spread spectrum （DSSS） communication systems using adaptive infinite impulse response （IIR） filter is presented. The excisi...A generalized approach for narrowband interference （NBI） suppression in direct sequence spread spectrum （DSSS） communication systems using adaptive infinite impulse response （IIR） filter is presented. The excision filter coefficients depend on both the jammer power and its instantaneous frequency. The dependency of the filter construction on the jammer power is significant as it allows optimal tradeoff between interference removal and signal distortion by maximizing the receiver signal to noise ratio improvement（SNRI）. Instead of traditional adaptive line enhancer （ALE） estimator, a preferable NBI estimator-Fourier interpolation estimator （FIE） is proposed. Closed-form expressions of the SNR improvement and theoretical bit error rate （BER） based on the assumption that the output of the correlator is Gaussian distributed are both derived. Performance results obtained by numerical simulation are also presented and compared with theoretical results.展开更多
A new Kalman filtering algorithm based on estimation of spread spectrum signal before suppression of narrowband interference （NBI） in spread spectrum systems, using the dependence of autoregressive （AR） interferen...A new Kalman filtering algorithm based on estimation of spread spectrum signal before suppression of narrowband interference （NBI） in spread spectrum systems, using the dependence of autoregressive （AR） interference, is presented compared with performance of the ACM nonlinear filtering algorithm, simulation results show that the proposed algorithm has preferable performance, there is about 5 dB SNR improvement in average.展开更多
An algorithm for carrier frequency offset estimation with narrowband interference in burstmode transmissions is proposed.The algorithm is data-aided and has a feedforward structure that can be easily implemented digit...An algorithm for carrier frequency offset estimation with narrowband interference in burstmode transmissions is proposed.The algorithm is data-aided and has a feedforward structure that can be easily implemented digitally.The principle of the algorithm is based on a properly designed training sequence and an interpolation technique.Simulation results indicate that the estimation range is about ±20% of the symbol rate.The performance is satisfactory for a signal-to-noise ratio（SNR）as low as -13 dB and the mean square error（MSE）is approximately irrelevant to signal-to-interference ratio（SIR）values over -20 dB.展开更多
Traditional lapped transform domain excision techniques obtain good performance at the expense of increased processing delay. Extension of transform domain filtering techniques to the lapped biorthogonal transform dom...Traditional lapped transform domain excision techniques obtain good performance at the expense of increased processing delay. Extension of transform domain filtering techniques to the lapped biorthogonal transform domain can help solve the problem. By incorporating biorthogonality into the lapped transforms, more flexibility is obtained in the design of windows. Thus transform bases with better stopband attenuation can be generated by designing windows, but not by increasing the overlapping factor. In this paper, a new modulated lapped biorthogonal transform (MLBT) with optimized windows is introduced for efficient compression of multi-tone interfering signal energy. The bit error rate (BER) performance of the receiver employing the proposed MLBT excision technique is analyzed and compared with that of the lapped transform domain excision-based receivers. Simulation results demonstrate the improved performance and increased robustness of the proposed technique.展开更多
With the advancement of electronic countermeasures,airborne synthetic aperture radar(SAR)systems are facing increasing challenges in maintaining effective performance in hostile environments.In particular,high-power i...With the advancement of electronic countermeasures,airborne synthetic aperture radar(SAR)systems are facing increasing challenges in maintaining effective performance in hostile environments.In particular,high-power interference can severely degrade SAR imaging and signal processing,often rendering target detection impossible.This highlights the urgent need for robust anti-interference solutions in both the signal processing and image processing domains.While current methods address interference across various domains,techniques such as waveform modification and spatial filtering typically increase the system costs and complexity.To overcome these limitations,we propose a novel approach that leverages the multi-domain characteristics of interference to efficiently suppress narrowband interference and repeater modulation interference.Specifically,narrowband interference is mitigated using notch filtering,a signal processing technique that effectively filters out unwanted frequencies,while repeater modulation interference is addressed through strong signal amplitude normalization,which enhances both the signal and image processing quality.These methods were validated through tests on real SAR data,demonstrating significant improvements in the imaging performance and system robustness.Our approach offers valuable insights for advancing anti-interference technologies in SAR systems and provides a cost-effective solution to enhance their resilience in complex electronic warfare environments.展开更多
This paper analyzes the performance of both in-band and outband narrowband interference suppression in orthogonal code modulation spread spectrum system, and compares with conventional spread spectrum system at the sa...This paper analyzes the performance of both in-band and outband narrowband interference suppression in orthogonal code modulation spread spectrum system, and compares with conventional spread spectrum system at the same information transmission rate and spread spectrum bandwidth. Simulation results indicate that the antijamming (narrowband interference) performance obtained from orthogonal code modulation spread spectrum system is much better than that from conventional spread spectrum system.展开更多
A novel direct sequence （DS） design method for suppressing the narrowband interference in DS spread spectrum ultra-wideband receivers is proposed. The method has low computational complexity and can be easily implem...A novel direct sequence （DS） design method for suppressing the narrowband interference in DS spread spectrum ultra-wideband receivers is proposed. The method has low computational complexity and can be easily implemented in practical systems. Simulation results prove that the proposed method is effective to suppress the narrowband interference. Therefore, the integrity of both the ultra-wide bandwidth and the narrowband systems can be highly enhanced.展开更多
基金The National Research and Development Program of China(863 Program)(No.2007AA12Z238)the Natural Science Foundation of Jiangsu Higher Education Institutions of China(No. 12KJD510008)
文摘A cognitive radio transmitted reference ultra-wideband（CR-TR-UWB） system is proposed to improve the performance of TR-UWB systems with narrowband interference（NBI） from primary users（PU）.The transmitter of the CR-TR-UWB system detects the band of PU,and then sends prolate spheroidal wave functions（PSWF） pulses with the same limited band as PU＇s to reduce interference with PU.The receiver uses a notch filter before autocorrelation to eliminate NBI from PU.The simulation results show that the bit error rate（BER） performance of the CR-TR-UWB system is close to that of TR-UWB systems without NBI when the system is interfered by single or double NBIs with a signal to interference ratio（SIR） of 0 dB,and if the signal to noise ratio（SNR） is 10 dB and the SIR varies from-20 to 10 dB,BER performance varies no more than an order of magnitude.The system has excellent resistance to NBI,strong robustness BER performance at different SNRs,and smaller interference with the same frequency band PU.
基金Sponsored by the Beijing Municipal Natural Science Foundation(4052024)
文摘A generalized approach for narrowband interference （NBI） suppression in direct sequence spread spectrum （DSSS） communication systems using adaptive infinite impulse response （IIR） filter is presented. The excision filter coefficients depend on both the jammer power and its instantaneous frequency. The dependency of the filter construction on the jammer power is significant as it allows optimal tradeoff between interference removal and signal distortion by maximizing the receiver signal to noise ratio improvement（SNRI）. Instead of traditional adaptive line enhancer （ALE） estimator, a preferable NBI estimator-Fourier interpolation estimator （FIE） is proposed. Closed-form expressions of the SNR improvement and theoretical bit error rate （BER） based on the assumption that the output of the correlator is Gaussian distributed are both derived. Performance results obtained by numerical simulation are also presented and compared with theoretical results.
基金Project supported by National Natural Science Foundation of Chi-na (Grant No .60172018)
文摘A new Kalman filtering algorithm based on estimation of spread spectrum signal before suppression of narrowband interference （NBI） in spread spectrum systems, using the dependence of autoregressive （AR） interference, is presented compared with performance of the ACM nonlinear filtering algorithm, simulation results show that the proposed algorithm has preferable performance, there is about 5 dB SNR improvement in average.
基金Supported by the National Natural Science Foundation of China(61301089)
文摘An algorithm for carrier frequency offset estimation with narrowband interference in burstmode transmissions is proposed.The algorithm is data-aided and has a feedforward structure that can be easily implemented digitally.The principle of the algorithm is based on a properly designed training sequence and an interpolation technique.Simulation results indicate that the estimation range is about ±20% of the symbol rate.The performance is satisfactory for a signal-to-noise ratio（SNR）as low as -13 dB and the mean square error（MSE）is approximately irrelevant to signal-to-interference ratio（SIR）values over -20 dB.
文摘Traditional lapped transform domain excision techniques obtain good performance at the expense of increased processing delay. Extension of transform domain filtering techniques to the lapped biorthogonal transform domain can help solve the problem. By incorporating biorthogonality into the lapped transforms, more flexibility is obtained in the design of windows. Thus transform bases with better stopband attenuation can be generated by designing windows, but not by increasing the overlapping factor. In this paper, a new modulated lapped biorthogonal transform (MLBT) with optimized windows is introduced for efficient compression of multi-tone interfering signal energy. The bit error rate (BER) performance of the receiver employing the proposed MLBT excision technique is analyzed and compared with that of the lapped transform domain excision-based receivers. Simulation results demonstrate the improved performance and increased robustness of the proposed technique.
文摘With the advancement of electronic countermeasures,airborne synthetic aperture radar(SAR)systems are facing increasing challenges in maintaining effective performance in hostile environments.In particular,high-power interference can severely degrade SAR imaging and signal processing,often rendering target detection impossible.This highlights the urgent need for robust anti-interference solutions in both the signal processing and image processing domains.While current methods address interference across various domains,techniques such as waveform modification and spatial filtering typically increase the system costs and complexity.To overcome these limitations,we propose a novel approach that leverages the multi-domain characteristics of interference to efficiently suppress narrowband interference and repeater modulation interference.Specifically,narrowband interference is mitigated using notch filtering,a signal processing technique that effectively filters out unwanted frequencies,while repeater modulation interference is addressed through strong signal amplitude normalization,which enhances both the signal and image processing quality.These methods were validated through tests on real SAR data,demonstrating significant improvements in the imaging performance and system robustness.Our approach offers valuable insights for advancing anti-interference technologies in SAR systems and provides a cost-effective solution to enhance their resilience in complex electronic warfare environments.
文摘This paper analyzes the performance of both in-band and outband narrowband interference suppression in orthogonal code modulation spread spectrum system, and compares with conventional spread spectrum system at the same information transmission rate and spread spectrum bandwidth. Simulation results indicate that the antijamming (narrowband interference) performance obtained from orthogonal code modulation spread spectrum system is much better than that from conventional spread spectrum system.
文摘A novel direct sequence （DS） design method for suppressing the narrowband interference in DS spread spectrum ultra-wideband receivers is proposed. The method has low computational complexity and can be easily implemented in practical systems. Simulation results prove that the proposed method is effective to suppress the narrowband interference. Therefore, the integrity of both the ultra-wide bandwidth and the narrowband systems can be highly enhanced.
