Time frequency overlap signal parameter estimation method under Alpha stable distribution noise

Abstract

The invention discloses a time frequency overlap signal parameter estimation method under Alpha stable distribution noise. The steps include: computing generalized fourth order circulation cumulants of the time frequency overlap signal under Alpha stable distribution noise and setting generalized fourth order circulation cumulant magnitude spectra beta-|GC<beta>(r, 40)| and beta-|GC<beta>(r, 42)| to zero in a small neighbourhood [0, delta0] in which the cycle frequency beta=0; detecting the highest spectrum lines P1 and P1* in beta-|GC<beta>(r, 40)| and beta-|GC<beta>(r, 42)| respectively according to a discrete spectrum line detection method, then setting the amplitude value GCmax of the spectrum line in beta-|GC<beta>(r, 40)| and the amplitude value GCmax* of the spectrum line in beta-|GC<beta>(r, 42)| to zero in small neighbourhoods [P1-delta0, P1+delta0] and [P1*-delta0, P1*+delta0], and thus cycle frequencies corresponding to P1 and P1* being a carrier wave velocity fc1 and a code element velocity fb1 of one of signal components of the time frequency overlap signal; and under the conditions that the code element velocities and the carrier wave frequencies of the overlap signal components are different, detecting the code element velocities of other signal components of the time frequency overlap signal in sequence according to the discrete spectrum line detection method, till the amplitude value GCk+1* of the (k+1)th spectrum line in beta-|GC<beta>(r, 42)| being smaller than GCmax* / 2, judging the number of mixed signals to be k at this time, and detecting the carrier wave frequencies of other signal components of the time frequency overlap signal in sequence according to the discrete spectrum line detection method.

Description

technical field [0001] The present invention relates to the field of communication technology, in particular to a method for parameter estimation of time-frequency overlapping signals under Alpha stable distributed noise, which can be used for the number of signal components, symbol rate and carrier frequency of time-frequency overlapping signals under Alpha stable distributed noise estimate. Background technique [0002] With the development of communication technology and the increasingly complex electromagnetic environment, there are more and more time-frequency overlapping signals in the communication field. If adjacent satellites are too close together, adjacent satellite signal interference will be formed, and the increasingly dense signals will cause same-frequency signal overlap. Wait. On the one hand, this type of signal greatly affects the receiving performance of the system; on the other hand, the traditional single-signal processing method is no longer suitable ...

AI Technical Summary

Problems solved by technology

For time-frequency overlapping signals, Wang Qinghong et al. used the fourth-order cyclic cumulant to estimate the number of signals. However, this method is limited by the type of overlapping signals and the number of components (Wang Qinghong, Peng Hua, Wang Bin, Teng Bo. Based on Co-channel multi-signal detection and signal source number prediction method based on cyclic cumulants[J]. Journal of Information Engineering University. 2012,13(2):184-188.)

Yu Ningyu and others used cyclic spectral envelope to estimate the carrier frequency and symbol rate of dual BPSK signal, but this method is limited by signal type and shaping filter (Yu Ningyu, Ma Hongguang, Shi Rong, Yu Zhibin. Based on Co-channel multi-signal parameter estimation based on cyclic spectral envelope[J].Journal of Southwest Jiaotong University,2011,64(6):904-909.)

[0004] For the carrier frequency estimation problem of time-frequency overlapping dual signals, Gong Mudan et al. proposed a carrier frequency estimation method based on the second-order cyclic cumulant, but this method is greatly affected by the carrier spacing, and its The influence of noise is ignored in the spectrum range (Gong Mudan, Guo Ronghui. Carrier frequency estimation based on second-order cyclic cumulants[J]. Computer Engineering, 2011,37(20):81-82.)

Zhu Bo and others proposed a spectrum refinement method based on the energy center, but this method does not give how to set the threshold value when estimating the carrier frequency. For other modulation type signals or when the frequency resolution changes, pre-set The threshold value will be invalid, so this method lacks universality, and the frequency prediction accuracy of this method is poor under the condition of low signal-to-noise ratio (Zhu Bo. Analysis and realization of single-channel time-frequency overlapping signal parameters based on wavelet[ D]. University of Electronic Science and Technology of China, 2011)

Wang Qinghong et al. used high-order cyclic cumulants to estimate the signal carrier frequency of time-frequency overlapped signals, but this method failed when Alpha stabilized the noise background (Wang Qinghong, Peng Hua, Zhang Jincheng. A co-channel multi-signal modulation based on cyclic spectrum Parameter estimation method [J]. Signal Processing, 2011, 27(8): 1153-1159)

In addition, the above research is only applicable to Gaussian noise environment, and these parameter estimation methods are invalid in non-Gaussian noise

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