A Cooperative Spectrum Sensing Method Based on Free Probability Theory
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A technology of collaborative spectrum sensing and probability theory, applied in transmission monitoring, electrical components, transmission systems, etc., can solve the problem of low spectrum sensing performance and achieve the effect of improving spectrum sensing performance and low signal-to-noise ratio
Active Publication Date: 2017-02-22
NANJING UNIV OF POSTS & TELECOMM
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[0006] The purpose of the present invention is to provide a cooperative spectrum sensing method based on free probability theory, which is suitable for MIMO communication environment, can obtain accurate received power from the received signal of the secondary base station, and solve the problem of low signal-to-noise ratio and small sample The problem of low spectrum sensing performance
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Embodiment 1
[0038] Such as figure 1 As shown, K secondary base stations BS distributed in different geographical locations 1 ,BS 2 ,...,BS K Cooperate to sense the channel, and judge whether the main base station is sending a signal. The primary base station and each secondary base station are equipped with N t and N r antennas with a MIMO Rayleigh fading channel between them. When the main base station sends a signal, the sampling rate is 1 / T s , then the sampling signal output by the kth receiver at time n can be expressed as
[0039]
[0040] in, is the transmitted symbol vector at time n, whose elements satisfy the zero-mean independent and identical distribution, and the variance is 1; is the MIMO channel matrix between the transmitter and the kth receiver, and its elements are complex Gaussian variables with mean 0 and variance 1, that is, obey N c (0,1);P k is the received signal power of each antenna of the kth receiver; is the complex Gaussian noise vector at the...
Embodiment 2
[0132] Such as figure 2 As shown, the present invention provides a cooperative spectrum sensing method based on free probability theory, which is suitable for MIMO communication environments, and specifically includes the following steps:
[0133] Step 1: Sampling the received signals of multiple antennas of each secondary base station, and the sampled signals will be processed centrally;
[0134] Step 2: According to the noise variance of all received sampling signals and channels, with the help of the asymptotic free characteristics of the random matrix and the Wishart distribution characteristics, the algorithm based on free deconvolution is used to solve the average received signal power of all receiving antennas That is, the detection statistic;
[0135] Step 3: According to the target false alarm probability p f , using Monte Carlo simulation to calculate the detection threshold τ in the presence of noise only;
[0136] Step 4: Put Compared with τ, it is judged wh...
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Abstract
The invention discloses a cooperative spectrum sensing method based on a free probability theory. The cooperative spectrum sensing method is suitable for an MIMO communication environment and includes the steps that received signals of a plurality of antennas of all auxiliary base stations are sampled, and sampled signals are processed in a centralized mode; according to noise variance of all the received sampled signals and channels, by means of the asymptotic freedom characteristic and the Wishart distribution characteristic of a random matrix, the average received signal power (img file=' DDA0000463198220000011. TIF' wi=' 64' he=' 54' / ) of all receiving antennas is solved by the adoption of a free deconvolution algorithm, and namely statistics are detected; according to target false alarm probability pf, a detection threshold value tau is calculated by using MonteCarlo simulation under the condition that only noise exsits; finally (img file=' DDA0000463198220000012. TIF' wi=' 41' he=' 54' / ) is compared with tau to judge whether a main base station sends signals or not. The accurate receiving power can be obtained through the received signals of the auxiliary base stations, and moreover the spectrum sensing performance can be improved effectively particularly under the condition of a low signal to noise ratio and small samples.
Description
technical field [0001] The invention relates to the technical field of computer communication of cognitive radio spectrum sensing, in particular to a cooperative spectrum sensing method based on free probability theory. Background technique [0002] Under the current spectrum fixed allocation method commonly adopted by various countries, the utilization rate of most licensed frequency bands is very low, which has caused a great waste of wireless spectrum resources. On the other hand, with the rapid development of the wireless communication industry, available wireless spectrum resources are increasingly scarce. How to meet the explosive growth of wireless spectrum demand has become a common problem faced by global mobile communications. Therefore, cognitive radio, as one of the effective ways to alleviate the shortage of wireless spectrum resources, has attracted extensive attention from academia and industry in recent years. The basic idea of cognitive radio is spectrum...
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