Table 1 List of the channel notations

h _sd

Channel from source to destination

$\mathcal{C}\mathcal{N}(0,{\sigma }_{\text{sd}}^2)$

h _sr

Channel from source to relay

$\mathcal{C}\mathcal{N}(0,{\sigma }_{\text{sr}}^2)$

h _rd

Channel from relay to destination

$\mathcal{C}\mathcal{N}(0,{\sigma }_{\text{rd}}^2)$

g _se

Channel from source to eavesdropper

$\mathcal{C}\mathcal{N}(0,{\sigma }_{\text{se}}^2)$

g _re

Channel from relay to eavesdropper

$\mathcal{C}\mathcal{N}(0,{\sigma }_{\text{re}}^2)$

f _ps

Channel from PU₁ to source

$\mathcal{C}\mathcal{N}(0,{\sigma }_{\text{ps}}^2)$

f _pr

Channel from PU₁ to relay

$\mathcal{C}\mathcal{N}(0,{\sigma }_{\text{pr}}^2)$

f _pd

Channel from PU₁ to destination

$\mathcal{C}\mathcal{N}(0,{\sigma }_{\text{pd}}^2)$

f _pe

Channel from PU₁ to eavesdropper

$\mathcal{C}\mathcal{N}(0,{\sigma }_{\text{pe}}^2)$