Scaling Limits of a Tandem Queue with Two Infinite Orbits

This paper considers a tandem queueing network with Poisson arrival process of incoming calls, two servers, and infinite orbits by the method asymptotic analysis. The servers provide services for calls exponentially distributed random times. Blocked customers at each server join orbit that retry to enter again after an time. Under condition low retrial rates, we prove joint stationary distribution scaled numbers in weakly converges two-variable Normal distribution.