International Core Journal of Engineering 2020-26 | Page 164
thus forming a fast fading of the signal is called Rayleigh
fading. Therefore, we compare the performance of the
proposed method with other detection methods in ideal channel
and Rayleigh fading channel respectively.
Fig. 3 shows the ROC curves of the proposed method
compared with the other two detection methods in ideal
channel and Rayleigh fading channel respectively. The
probability of detection is P d (SNR = -10 dB). The detection
probability increases with the increase of false alarm
probability under the specified SNR. In the case of low false
positive rate, the detection performance of the algorithm is
significantly better than CED. Compared with the 3EED
probability, the detection performance of 5IED has been
significantly improved. However, the performance of various
detectors in the Rayleigh fading channel has dropped
significantly. At the same time, it is obvious that the
performance of the proposed method is significantly better
than CED and 3IED even in the fading channel.
Fig. 2. Probability of detection against SNR in Gaussian noise
In the actual wireless communication scenario, the
performance of signal detection tends to drop sharply due to
factors such as Rayleigh fading. It can be seen from Fig. 4 (P f
=0.01) that the performance of signal detection in the Rayleigh
fading channel is reduced by nearly 5dB compared with the
ideal channel. However, when in the same channel model, our
proposed method is still superior to classic energy detection
and 3EED.
B. Average Detection Time
In the following, we evaluated the ADT required for three
primary signal detection techniques ADT is defined as the
average number of samples (i.e. time) required before the
correct detection is declared. ADT can be expressed as follows
[16]:
ADT
L P
f
u T p u
2 P d
2 u P d
(14)
Fig. 3. ROC curves of the three detection methods
Where L is the number of sensing samples (i.e. L = N) and
the penalty time Tp is the time it takes to recover from the
wrong decision (i.e. the band in which the empty PU actually
transmits) Tp =10L. Then, we define the ADT gain as the ratio
of the ADT of the CED and 3EED to the ADT of the proposed
method.
Fig. 4. Probability of SNR detection in different models
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