Performance analysis of priority control schemes in ATM networks

Abstract

The main objective of this dissertation work is to investigate the performance of priority control schemes in broadband ATM networks. ATM will be the central vehicle on which the future broadband information infrastructures are to be constructed. Priority control is one of the necessary traffic control schemes that are needed to achieve the efficiency of ATM networks. Priority control can be used either in the cell level or in the burst level, to increase the utilization of ATM networks, while meeting different QoS requirements of different traffic sources. In this dissertation, first, cell level priority controls are studied in the model of an input queueing nonblocking ATM switch. The ATM switch model consists of input and output queues together with a nonblocking switching fabric in between. The speed-up factor of the switching fabric is allowed to take any positive integer value. To each input queue of the switch, we apply and study the push-out, the partial buffer sharing or the push-out-with-depth scheme successively, together with a common state-dependent scheduling scheme. We have chosen the state-dependent scheduling scheme, because of its generality in representing the various specific time priority control schemes such as head-of-line (HOL), queue length threshold (QLT), and Bernoulli scheduling (BS) schemes. Assuming two classes of independent Bernoulli traffics, a common analytical procedure is developed and used for the three different combinations of space and time priority control schemes. The analysis is carried out in two steps in the discrete-time domain, to obtain loss probabilities and mean waiting times of the two classes of traffic. First, the virtual queue comprising of HOL cells destined for the same output port is analyzed to obtain the HOL contention time distributions of the two classes of traffic. Second, we begin with establishing the state transition probabilities of the input queue for each particular combination of space and ...