Performance of dynamic bandwidth allocation algorithms in passive optical networks

The paper covers the issue of shared medium access in passive optical networks (PONs). To solve the problem dynamic bandwidth allocation is used and its effectiveness analyzed. Performances of traditional Interleaved Polling with Adaptive Cycle Time (IPACT) algorithms in conventional PONs are compared to those in long reach Passive Optical Networks (LR-PONs). Algorithms implement the basic mechanisms necessary for achieving efficient shared medium access in passive optical networks, but lack particular characteristics that may be needed in topologies, such as LR-PON. The algorithms are compared with respect to the following parameters: average packet delay, polling cycle time, number of optical network units (ONU). The simulation results show degradation in traditional IPACT algorithms performance when used on LR-PON topology setup. This is an expected performance outcome due to longer round-trip times between Optical Line Terminal (OLT) and each ONU. The paper also shows why research, in recent years, has been concentrated on expanding PON topology with WDM solutions - forming some kind of hybrid system - more adequate for higher split ratio of future generation PONs.