Multiple-tone interference is a kind of narrow band interference appears in Direct Sequence (DS) Spread Spectrum (SS) communication system frequently that degrades the system performance. Most open literature studies ...Multiple-tone interference is a kind of narrow band interference appears in Direct Sequence (DS) Spread Spectrum (SS) communication system frequently that degrades the system performance. Most open literature studies on narrowband interference rejection assumed stationary SS signal and interference. SS signal and interference are modeled as cyclostationary and based on cyclostationary model, an interference rejection algorithm is proposed. Through computer simulation, it is shown that the performance of the SS system can be improved considerably after adopting this algorithm.展开更多
A new method for the rejection of linear frequency modulation (LFM) interference in direct sequence spread spectrum (DSSS) system based on the fractional Fourier transform is proposed, and the configuration of the rec...A new method for the rejection of linear frequency modulation (LFM) interference in direct sequence spread spectrum (DSSS) system based on the fractional Fourier transform is proposed, and the configuration of the receiver with an interference exciser is also presented. Based on the property that the fractional Fourier transform of a signal is equivalent to rotating the signal in the time-frequency plane, the received signal is transform into a certain fractional Fourier domain, this transform will result in the least spectrum overlap between the signal and interference. Then, a narrowband filter is exploited to extract most of the interference energy. The performance analyses show that remarkable improvements in signal-to-noise ratio (SNR) and bit-error-ratio (BER) are obtained.展开更多
In bistaic acoustic testing, there will be strong direct blast interference. An algorithm based on signal phase-matching array processing that rejects direct blast interference in bistatic acoustic testing has been st...In bistaic acoustic testing, there will be strong direct blast interference. An algorithm based on signal phase-matching array processing that rejects direct blast interference in bistatic acoustic testing has been studied, through which the object scattering signal is accurately extracted. Characteristics of bistatic acoustic testing and signal phase matching processing principle are fully integrated in this algorithm. Firstly, the direct blast interference is calculated from the receiving signal based on three subarrays signal phase matching processing. Secondly, the direct blast is rejected by subtraction from the receiving signal. In this way the limitations of the high signal to noise ratio that signal phase matching processing required for direct calculating the object scattering signal can be avoided. Simulation and sea trial results show that, when the ratio of signal to interference is greater than -20 dB, this algorithm of direct blast interference rejection based phase matching signal processing can accurately extract the object scattering signal.展开更多
To reduce the negative impact of channel quantization errors, a low-complexity transceiver joint design scheme for both the transmit beamformers and receive combining vectors is proposed in the two-user multiple-input...To reduce the negative impact of channel quantization errors, a low-complexity transceiver joint design scheme for both the transmit beamformers and receive combining vectors is proposed in the two-user multiple-input multiple-output (MIMO) system. In the scheme, the channel nullspace quantization vector is used as the transmit beamformer of the interference user directly based on channel null-space feedback. Since the interference can be determined at the receiver, interference rejection combining (IRC) is jointly utilized to cancel the inter-user interference. Simulation re- sults show that the proposed scheme can provide substantial sum-rate improvement especially at high SNR.展开更多
Electromagnet interference troubles are more and more and complex with each pass day along with improvement of large system electronization. This article will analyze the interference problems caused by harmonic waves...Electromagnet interference troubles are more and more and complex with each pass day along with improvement of large system electronization. This article will analyze the interference problems caused by harmonic waves in large system. The generation,characteristic and perniciousness of harmonic waves will be qualitatively analyzed for summarizing practical experience to provide mentality and method for settling the large system electromagnet interference trouble. This article raises the approach and method of harmonic suppression from the root of harmonic generation during ultrashort wave transmission and through actual test and analyzing verification. The effectivity and correctness of the methods adopted are certified by theoretical analysis and experimental verification.展开更多
文摘Multiple-tone interference is a kind of narrow band interference appears in Direct Sequence (DS) Spread Spectrum (SS) communication system frequently that degrades the system performance. Most open literature studies on narrowband interference rejection assumed stationary SS signal and interference. SS signal and interference are modeled as cyclostationary and based on cyclostationary model, an interference rejection algorithm is proposed. Through computer simulation, it is shown that the performance of the SS system can be improved considerably after adopting this algorithm.
文摘A new method for the rejection of linear frequency modulation (LFM) interference in direct sequence spread spectrum (DSSS) system based on the fractional Fourier transform is proposed, and the configuration of the receiver with an interference exciser is also presented. Based on the property that the fractional Fourier transform of a signal is equivalent to rotating the signal in the time-frequency plane, the received signal is transform into a certain fractional Fourier domain, this transform will result in the least spectrum overlap between the signal and interference. Then, a narrowband filter is exploited to extract most of the interference energy. The performance analyses show that remarkable improvements in signal-to-noise ratio (SNR) and bit-error-ratio (BER) are obtained.
基金supported by the Foundation of Key Laboratory for Underwater Test & Control Technology under Grant No.9140C260201110C26
文摘In bistaic acoustic testing, there will be strong direct blast interference. An algorithm based on signal phase-matching array processing that rejects direct blast interference in bistatic acoustic testing has been studied, through which the object scattering signal is accurately extracted. Characteristics of bistatic acoustic testing and signal phase matching processing principle are fully integrated in this algorithm. Firstly, the direct blast interference is calculated from the receiving signal based on three subarrays signal phase matching processing. Secondly, the direct blast is rejected by subtraction from the receiving signal. In this way the limitations of the high signal to noise ratio that signal phase matching processing required for direct calculating the object scattering signal can be avoided. Simulation and sea trial results show that, when the ratio of signal to interference is greater than -20 dB, this algorithm of direct blast interference rejection based phase matching signal processing can accurately extract the object scattering signal.
基金Supported by the Sino-Swedish IMT-Advanced and Beyond Cooperative Program(2008DFA11780)
文摘To reduce the negative impact of channel quantization errors, a low-complexity transceiver joint design scheme for both the transmit beamformers and receive combining vectors is proposed in the two-user multiple-input multiple-output (MIMO) system. In the scheme, the channel nullspace quantization vector is used as the transmit beamformer of the interference user directly based on channel null-space feedback. Since the interference can be determined at the receiver, interference rejection combining (IRC) is jointly utilized to cancel the inter-user interference. Simulation re- sults show that the proposed scheme can provide substantial sum-rate improvement especially at high SNR.
文摘Electromagnet interference troubles are more and more and complex with each pass day along with improvement of large system electronization. This article will analyze the interference problems caused by harmonic waves in large system. The generation,characteristic and perniciousness of harmonic waves will be qualitatively analyzed for summarizing practical experience to provide mentality and method for settling the large system electromagnet interference trouble. This article raises the approach and method of harmonic suppression from the root of harmonic generation during ultrashort wave transmission and through actual test and analyzing verification. The effectivity and correctness of the methods adopted are certified by theoretical analysis and experimental verification.