Before revision:  A necessary condition for the validity of this approach in the asymptotic sense (when the number of wireless nodes tends to infinity) is the existence and uniqueness of a solution to a fixed point equation .
After revision:  This decoupling assumption results from mean field convergence and is generally true in transient regime in the asymptotic sense (when the number of wireless nodes tends to infinity) is the existence and uniqueness of a solution to a fixed point equation .