Algorithm 2 SCA-based power optimization for D2D links during each iteration

1:Initialize$(\mathbf{\varphi },\mathit{p},{\tau }_e)$ with the output of Algorithm 1. Set the current iteration $l=0$ and the initial local point ${\mathit{p}}^{\mathit{l}}=\mathit{p}$. 2:while The improvement of the objective function in (27) is higher than a predefined threshold ${ϵ}_1$ do. 3:    Solve Problem (27) for a given $\eta$ using the interior point method and obtain the optimal solution ${\mathit{p}}^{\mathit{l}*}$. 4:    Update $\eta =R_{lb}^D({\mathit{p}}^{\mathit{l}*})/P^{con,D}({\mathit{p}}^{\mathit{l}*})$. 5:    Set ${\mathit{p}}^{\mathit{l}+\mathbf{1}}={\mathit{p}}^{\mathit{l}*}$ and update $l=l+1$. 6:Output the optimal power strategy ${\mathit{p}}^{\mathit{l}*}$ and $(\mathbf{\varphi },{\tau }_e)$ to the next block.