An Analytical Approach for Dynamic Wavelength Allocation in WDM–TDMA PONs Servicing ON–OFF Traffic

Optical access systems are now considered a feasible alternative to the predominant broadband access technologies, while, at the same time, passive optical networks (PONs) are viewed as an attractive and promising type of fiber access system. In this paper we present and analyze three basic dynamic wavelength allocation scenarios for a hybrid wavelength division multiplexing-time division multiple access (WDM-TDMA) PON. We propose new teletraffic loss models for calculating call-level performance measures, like connection failure probabilities (due to unavailability of a wavelength) and call blocking probabilities (due to the restricted bandwidth capacity of a wavelength). The PON accommodates bursty service-classes of ON-OFF traffic. The proposed models are extracted from one-dimensional Markov chains, which describe the wavelength occupancy in the PON, and two-dimensional Markov chains, which describe the bandwidth occupancy inside a wavelength. The accuracy of the proposed models is validated through simulation and is found to be quite satisfactory. Moreover, these models are computationally efficient because they are based on recursive formulas.