Abstract
Energy detection (ED) method is one of the most commonly used signal-sensing methods in spectrum sensing due to its low implementation complexity. ED can achieve good detection performance when the noise variance is known. However, in most cases, the noise variance is estimated, which may result in the uncertainty in noise variance. In the presence of noise variance uncertainty, the detection performance of the ED method may degrade significantly. To reduce the impact of uncertainty in noise variance, an ED-based sensing method is proposed in this paper. This method combines these signal samples sampled by multiple antennas to obtain the decision statistic as ED does. A novel technique is proposed to construct the decision threshold so that it is independent of the noise variance. As a consequence, the proposed method is free of the effect of noise variance uncertainty, and the noise variance estimation is not need. The simulation results show that the detection probability of this method can approach to 1 even when the SNR is −15 dB while the detection probability of ED is below 0.8, which means the detection performance of the proposed method can outperform the ED method without the noise variance estimation when the number of antennas is greater than two.
Highlights
A cognitive radio (CR) is a radio which is able to sense the spectral environment over a wide spectrum band and exploit the spectrum usage information to opportunistically provide wireless links that best meet the user communication requirements [1]
Effective spectrum reallocation mainly relies on the good performance of spectrum sensing, and spectrum sensing is considered one of the critical elements in a CR system [2]. e basic function of spectrum sensing in CR systems is to detect the presence of primary users’ (PUs) signal
We propose an energy detection (ED)-based blind-sensing method, exploiting the low implementation complexity and without needing any prior information about PUs’ signal of the ED method. e proposed method is intended for CR systems with multiple antennas to exploit antenna diversity to get two relevant statistics
Summary
A cognitive radio (CR) is a radio which is able to sense the spectral environment over a wide spectrum band and exploit the spectrum usage information to opportunistically provide wireless links that best meet the user communication requirements [1]. Ese classic methods can achieve good sensing performance when given the sufficient information, including PUs’ signal waveform, the noise variance, and the cyclic frequency of the PUs’ signal. The methods proposed in [10,11,12,13] use multiple antennas and the characteristics of covariance matrix to detect the PUs’ signal without the prior information about PUs’ signal and noise variance. We propose an ED-based blind-sensing method, exploiting the low implementation complexity and without needing any prior information about PUs’ signal of the ED method. Us, the decision performance of the proposed method is free of the impact of uncertainty in noise variance, and noise variance estimation is not required which makes this method be a blind-sensing method.
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