Priority queues and their applications to telecommunication systems

Abstract

In this thesis, we consider priority queueing systems with two classes of customers. These systems have many applications in the areas such as ATM (Asynchrnous Transfer Mode) switching system in BISDN(Broadband Integrated Services Networks) and cellular mobile radio communication system. In chapter 2, we investigate an M/G/1 priority retrial queueing system which has applications in a telephone switching system and a cellular mobile communication system. Customers are identified as calls and classified into type I calls and type II calls. In the case that arriving calls are blocked due to a server being busy, type I calls are queued in a priority queue of finite capacity whereas type II calls enter a retrial group in order to try service again after a random amount of time. We derive the joint generating function for the numbers of calls in the priority queue and the retrial group in a closed form. Further we obtain mean waiting times of calls, blocking probability of type II calls and loss probability caused by capacity constraint on the priority queue. In chapter 3, we investigate priority queueing systems of two classes of customers, where customers of high priority class arrive in accordance with Markov-modulated Poisson process (MMPP) or Markov-modulated fluid flow (MMFF) and arrival process of customers of low priority class is modeled accordingly by Poisson process or fluid flow with constant rate. The steady-state joint generating function of the queue lengths of each class has been obtained in both queueing systems. Furthermore, from these results, we obtain mean waiting times and mean queue lengths and variances of queue lengths of each class. In the queueing system with MMFF arrival, these performance measures have more efficient and stable computational algorithm than in the corresponding queueing system with MMPP arrival. Numerical results have been presented to compare two queueing systems by the performance measures. It is shown that the result...