A Cooperative Spectrum Detection Technique in Non-Gaussian ...

value of all the cooperative cognitive users. Then, the selected users cooperatively detect the
primary users signal based on OR rule. The final decision declares whether the primary user is
present or not. The cooperative detection probability and the cooperative false alarm probability
when L cognitive users take participate in the cooperation are given by [9] :
If the cooperative probability of false alarm
probability of false alarm, , is given by
P
fa , i
L
−∏ (1 −
P fa
= 1 P , P d
= 1 − ∏ (1 − P
(15)
, c
fa,
i
)
1
L
, c
d , i
)
1
P
fa ,
is to be fixed, from (15) the individual CU’s
c
P L
fa, i
1 − (1 − Pfa,
c
)
= (16)
From (13) and (16), the threshold of each user for the Rao detector is
' −1
1
2
γ
i
= ( Q ( P
fa , i
))
2
i = 0,1, L
(17)
Finally, the cooperative detection probability based on the OR rule is
2
where λ
i
= SNR
iσ
i I
f , i
.
P
L
∏
= 1 − (1 −P
)
dc , di ,
1
L
'
'
1 ∏(1 ( Q( ri λi) Q( ri λi)))
1
= − − − + +
(18)
4. Simulation Results
4.1 Mixed-Gaussian Rao and Gaussian Rao detection
Figure 3. ROC for Mixed-Gaussian Rao and Gaussian Rao detection
287