Broadband signal detection and identification method based on Nyquist under-sampling

Abstract

The invention relates to a broadband signal detection and identification method based on Nyquist under-sampling. The method includes the following procedures that Nyquist under-sampling data of a front end are simulated and serve as the input of a signal reconstruction module, signal reconstruction is based on an SOMP algorithm, an energy observed value is generated each time iteration is conducted and used for spectrum detection, and meanwhile recovered frequency domain signals are used for cyclic spectrum estimation. In spectrum detection, a constant false alarm detector is adopted for making a broadband spectrum binary judgment and a multi-user identification module uses user bandwidth constraint for eliminating glitches generated by the constant false alarm detector. A cyclic spectrum estimation module uses the recovered signals and a multi-user identification result for estimating a cyclic spectrum of each user and finally, the modulation format identification, the symbol rate estimation and the carrier estimation of each user signal are achieved according to the features of cyclic spectrums of various digital communication signals. According to the method, wide spectrum detection and digital communication signal detection can be achieved at the same time.

Description

technical field [0001] The invention relates to the field of communication technology, in particular to a wideband signal detection and identification method based on sub-Nyquist sampling. Background technique [0002] With the development of various wireless communication services, spectrum resources are increasingly scarce, but the existing wireless communication systems all adopt a fixed channel allocation strategy, resulting in low spectrum utilization. In order to improve spectrum utilization, cognitive radio technology performs wireless random access through the results of spectrum sensing. One of its key technologies is spectrum detection, which identifies unused frequency bands in a large frequency range. On the other hand, in the monitoring of the electromagnetic environment, it is also necessary to carry out modulation format identification, symbol rate estimation and carrier estimation for each user signal. [0003] In order to quickly detect multiple users distr...

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Problems solved by technology

[0003] In order to quickly detect multiple users distributed in the broadband range and their occupied frequency bands at one time, the digital signal sampled by the analog front-end needs to be able to retain the original information. According to the Nyquist sampling law, the sampling of the analog / digital converter The frequency is at least 2 times the maximum frequency. In practical applications, the sampling frequency will reach more than 5 times the maximum frequency. For a system with a detection spectrum width of GHz, ordinary devices are powerless, and an excessively high sampling frequency will lead to higher power. consumption

Since the existing wireless communication systems all adopt fixed channel allocation strategies, in the actual environment, the authorized users allocated to the spectrum use rights only work part of the time, which makes the entire broadband signal have a large frequency domain sparsity

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