Frequency spectrum sensing method based on variance of polarization distance

Abstract

The invention provides a frequency spectrum sensing method based on a variance of a polarization distance, which is applicable to a cognitive radio network. The method comprises the steps that a system detection threshold is set; spatial electromagnetic signals are sampled continuously; frequency domain signal samples are obtained through fast Fourier transformation; signal frequency domain Stokes vectors are obtained by utilizing the frequency domain signal samples; the variance of the polarization distance of received signals is obtained based on the polarization distance between adjacent frequency points; and whether the electromagnetic signals exist or not is judged according to differences of signal polarizability and noise polarizability. The method can achieve that electromagnetic signal polarization information of an authorized user can be utilized; the problem of noise uncertainty existing in practices is solved; the variance of a signal polarization distance is estimated on the basis of the received signals; the detection is performed without prior knowledge of the signals, signal channels or noises; the polarization mode dispersion in a wireless signal channel can be avoided; and the high-efficiency utilization of a signal polarization state is facilitated.

Description

technical field [0001] The invention belongs to the field of wireless communication, in particular to a spectrum sensing method of cognitive radio. Background technique [0002] With the development of wireless communication technology, people's demand for wireless spectrum resources is increasing day by day. However, wireless spectrum is a non-renewable precious resource. It is an urgent problem to be solved in the field of wireless communication to make full use of spectrum resources and improve spectrum utilization to meet the growing wireless communication services. Cognitive radio (CR, Cognitive radio) technology, as an intelligent spectrum sharing technology, can effectively solve the contradiction between the scarcity of spectrum resources and the ever-increasing traffic volume. In the CR system, unlicensed users with cognitive functions (CR users) need to quickly and accurately perceive idle licensed user frequency bands, so that unlicensed users can use them for c...

AI Technical Summary

Problems solved by technology

These detection methods have their own shortcomings. For example, although energy detection is simple to implement, it cannot overcome the noise uncertainty problem in practice; matched filters need to know the prior information of authorized users; cyclostationary feature detection requires authorized user signals to be cyclostationary. characteristics; and the maximum and minimum eigenvalue detection has problems such as high computational complexity

In the actual communication environment, due to the fading of the wireless channel, the noise uncertainty of the channel, and the lack of prior information of authorized users, the above spectrum sensing method has obvious defects in the actual system and is not universally applicable.

[0004] In addition, on the one hand, with the widespread application of dual-polarized antennas in wireless communications, the identification and utilization of signal polarization information has become possible

However, traditional spectrum sensing methods are based on the analysis of scalar information such as amplitude, phase or frequency information of the received signal, but the vector information-polarization information, which can also reflect the essential properties of the signal, has not been applied, which results in the inherent analysis of the signal. Great loss of information utilization; on the other hand, the use of polarization information for detection needs to fully consider the effects of wireless channel depolarization, channel polarization sensitivity loss, polarization mode dispersion (Polarization Mode Dispersion, PMD) and other phenomena on the signal polarization state Impact

This will make it more difficult for spectrum sensing technology to effectively use signal polarization information

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