M/G/1/r retrial queueing systems with priority of primary customers

We analyze a single-server retrial queueing system with finite buffer, Poisson arrivals, and general distribution of service time. If an arriving customer finds the queue completely occupied he joins a retrial group (or orbit) in order to seek service again after an exponentially distributed amount of time. We obtain a stationary distribution of the primary queue size, a recurrent algorithm for the factorial moments of the number of retrial customers and an expression for the expected number of customers in the system.