A Phase-Type Representation for the Queue Length Distribution of a Semi-Markovian Queue

Abstract--In this paper we study a broad class of semiMarkovian queues introduced by Sengupta. This class contains many classical queues such as the GI/M/1 queue, SM/MAP/1 queue and others, as well as queues with correlated interarrival and service times. Queues belonging to this class are characterized by a set of matrices of size m and Sengupta showed that its waiting time distribution can be represented as a phase-type distribution of order m. For the special case of the SM/MAP/1 queue without correlated service and inter-arrival times the queue length distribution was also shown to be phasetype of order m, but no derivation for the queue length was provided in the general case. This paper introduces an order m2 phase-type representation (, K) for the queue length distribution in the general case. Moreover, we prove that the order m2 of the distribution cannot be further reduced in general. Examples for which the order is between m and m2 are also identified. We derive these results...

• Type: Journal
• Year: 2010
• Where: QEST
• Authors: Benny Van Houdt
• Keywords: Inter-arrival Times, Modeling And Simulation, QEST 2010, Queue Length, Queue Length Distribution