Table 1 The used symbols and their description

S

Secondary source

G

D _k

k ^th secondary destination

h _{s , p}

R

Secondary relay

h _{s , r}

P

Primary user

h _{r , p}

\(\mathcal {I}_{\mathsf {p}}\)

Interference threshold

h _r,k

P _s

Transmit power at S

n _{s , r}

x

Source symbol

n _r,k

P _R

Transmit power at R

N ₀