Algorithm 2. Transmission Mode and Relay Selection Optimization
1:	Solving optimal power allocation subproblem
	to obtain ${\eta }_m^{*}$ and ${\eta }_{m,k}^{*}$, construct Table 1
2:	for the mth PU
	if ${\eta }_m^{*}>{\eta }_{m,k}^{*}$, $\forall 1\le k\le K$
		then
		set ${\beta }_m^{(\mathrm{p},\mathrm{d})}=1$
		delete the mth row in Table 1b
		end
	end
	Table 1b is updated
3:	repeat
4:	Apply K-M algorithm on Table 1b to find
	optimal relay node obtaining ${\beta }_{m,k}^{\left(\mathrm{c}\right)}$
5:	if${\beta }_{m,k}^{\left(\mathrm{c}\right)}{\eta }_{m,k}^{*}<{\eta }_m^{*},1\le m\le M$
		set ${\beta }_m^{(\mathrm{p},\mathrm{d})}=1$
		set ${\beta }_{m,k}^{\left(\mathrm{c}\right)}=0$
		Update Table 1b removing the mth row
	end
6:	until${\beta }_{m,k}^{\left(\mathrm{c}\right)}{\eta }_{m,k}^{*}>{\eta }_m^{*}$,∀ PU${}_m$ in Table 1b.