Multiconstraints fuzzy-logic-based scheduling algorithm for passive optical networks

Presented is a fuzzy-logic-based scheduling algorithm for passive optical networks (PONs) that considers four different metrics to allocate an upstream bandwidth to optical network units (ONUs). The metrics considered are the delay of the head-of-the-line packets at the ONUs, the importance level of the packets, the relative ONU's buffer fullness, and the level of the power fluctuation from one ONU to another. One of the advantages of a fuzzy controller is the fact that, regardless of the design complexity, the controller can be implemented as a simple look-up table, which makes it ideal for high-speed operation. Further facilitation of implementation was achieved by realization of the fuzzy algorithm through a two-stage hierarchal architecture. Moreover, linear predictive filters have been used to predict the traffic arrival rate and the packet delay at the ONUs. Compared with the round-robin scheduling algorithm, the results show significant performance improvement in terms of the overall packets delay as well as jitter when the proposed algorithm in employed. Furthermore, using this algorithm would reduce the average level of power fluctuations in a PON system and will also provide high-level service differentiation between packets of different importance.