Algorithm 1 Iterative Content Placement Algorithm

Initialize$\left\{x_m^f\right\}$ based on the global popularity, that is each SBS caches the most popular contents of the overall network; repeat     Obtain the $\left\{{\tilde{a}}_{m,n}^{k*}\right\}$ based on interior point method or ellipsoid method;      Obtain $\left\{x_m^{f^{*}}\right\}$ based on Equation (8);      $T=T+1$; until No performance improvement could be obtained or $T\ge T_{max}$.