A three preemptive priority queuing system is considered where customers with three priorities joined a queue according to a Poisson process. A customer with higher priority needs to enter the service immediately upon arrival. The recursive formulas approach was extended to determine the steady state probabilities of such a priority queuing system.
Alawneh, Ameen Jameel
"Steady State Probabilities of a Three Preemptive Single Server Queue,"
Journal of Modern Applied Statistical Methods: Vol. 11
, Article 17.
Available at: http://digitalcommons.wayne.edu/jmasm/vol11/iss1/17