Packet Delay Analysis for Priority-Based Passive Optical Networks

Passive optical network (PON) systems are rapidly becoming the most promising and cost-effective class of fiber access systems. In this paper we investigate the performance of a simple PON configuration, in respect of the end-to-end packet delay. The network supports multiple service-classes with priorities, in terms of the number of packets that can be transmitted in each transmission period. We calculate the mean queueing delay of a packet, by taking into account the fact that packets are serviced in batches. The queueing delay is defined through the formulation of two queuing models; an M/D/1 model for the batches, and an M/D/m model for the individual packets. We also study the effect of the packet arrival rate of different service-classes, and the effect of the distribution of the packets into a frame, on the end-to-end packet delay. The accuracy of the proposed model is validated by simulation and was found to be quite satisfactory.