The association of UE$_j$ with BS$_i$ is given by an integer variable $\alpha_{ij}$. If UE$_j$ is associated with BS$_i$ $\alpha_{ij}=1$ else $\alpha_{ij}=0$ i.e., \begin{equation} \label{intCons} \alpha_{ij}\in\{0,1\}, \quad \forall i,\forall j. \end{equation} Though it is a multi-BS reception system, macrodiversity is not considered. Each UE is associated with only one BS. It is expressed as \begin{equation} \label{assign_cons} \sum_{i=1}^M \alpha_{ij}=1, \quad \forall j. \end{equation} The considered Quality of Service (QoS) metric is the UE rate. With threshold rate $r_{th}$, the constraint is given as \begin{equation} \label{qos_cons} \sum_{i=1}^M \alpha_{ij}r_{ij} \geq r_{th}, \quad \forall j, \end{equation} The bounded UE power is \begin{equation} \label{pow_cons} p_j \in [0,P_{max}], \quad \forall j. \end{equation}