\centering
\caption{SUMMARY OF NOTATIONS}\label{tab:notice}
\begin{tabular}{ l|l } //设置竖线
\hline //设置横线
\hline
$K$ & Number of BSs on the network \\
$K$-1 & Number of SBSs on a macrocell \\
$N$ & Number of RBs on a macrocell \\
$U$ & Number of UEs on a macrocell \\
$\mathcal{K}$ & Index set of BSs, $\{1,2,\ldots,K\}$\\
$\mathcal{K}_n$ & Index set of BSs using $n$-th RB, $\{1,2,\ldots,k_n\}$\\
$\mathcal{N}$ & Index set of RBs, $\{1,2,\ldots,N\}$\\
$\mathcal{N}_k$ & Index set of RBs allocated to SBS $k$, $\{1,2,\ldots,N_k\}$\\
$\mathcal N_{k,u,s}$ & Index set of residual RBs after $s$-1 subproblems, \\ &$\{1,2,\ldots,N_{k,u,s}\}$\\
$\mathcal{U}_K$ & Index set of UEs associated MBS $K$, $\{1,2,\ldots,U_K\}$\\
$\mathcal{U}_k$ & Index set of UEs associated SBS $k$, $\{1,2,\ldots,U_k\}$\\
$Y$ & association indication matrix \\
$A$ & RB indication matrix \\
$p_k$ & the transmission power of user u associated with BS $k$ \\
$g_{k,u,n}^k$ & path gain of user $u$ associated with BS $k$ to BS $k$ on RB \\ $\sigma_{n}^2$ & noise power \\
$\lambda_{k}$ & dual variable for the load of BS $k$\\
$\alpha_{k}(t)$ & the HS weight of the $t-1$ iteration\\
\hline
\hline
\end{tabular}
\end{table}