Spectrum sensing method for ofdm signal in the case of time asynchrony and frequency offset

Abstract

The invention discloses an OFDM signal spectrum sensing method for time synchronization and no frequency offset situations. The method comprises the following steps: sampling a received signal from a monitoring channel to obtain a sampling signal; then performing estimation by using the autocorrelation of cyclic prefixs of OFDM signals in the received signal according to the sampling values of all sampling points in the sampling signal in time synchronization and no frequency offset situations to obtain noise power; calculating a covariance matrix of the sampling signal according to the sampling values of the sampling points in the sampling signal; then calculating test statistics according to the noise power and the covariance matrix of the sampling signal; and finally comparing the test statistics with an obtained judgment threshold, and judging whether an authorized user signal exists in the monitoring channel to realize spectrum sensing; and the OFDM signal spectrum sensing method has the advantages of effectively improving the spectrum sensing performance of OFDM signals and ensuring low computational complexity.

Description

technical field [0001] The present invention relates to a spectrum sensing method in a cognitive radio system, in particular to a noise power estimation-based OFDM signal spectrum sensing method for time asynchronous and frequency offset conditions. Background technique [0002] With the rapid development of various wireless communication services and emerging communication technologies (such as ZigBee technology, fast access module, LTE technology, ultra-wideband network, etc.), the importance and scarcity of spectrum resources have become increasingly prominent. A large number of studies have shown that the current shortage of spectrum resources is not due to the physical shortage of frequency resources, but mainly due to the low spectrum utilization rate caused by the fixed spectrum allocation management mechanism. Cognitive radio is proposed to essentially solve the problem of increasingly scarce wireless communication resources by improving spectrum utilization. The co...

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Problems solved by technology

The covariance matrix-based spectrum sensing method proposed by Zeng et al. in "Spectrum sensing algorithms for cognitive radio based on statistical covariance (spectrum sensing method based on statistical covariance in cognitive radio)" in 2009 can utilize the Correlation is used to realize spectrum sensing, which has the characteristics of low calculation amount, but this method does not consider the specific situation of time asynchrony and frequency offset, so it cannot effectively use the cyclic prefix autocorrelation characteristic of OFDM signal

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