Energy Efficiency Analysis of the Watchful Sleep Mode with Delayed Wakeup in PONs

Over the last decade, passive optical network (PON) has been taken as the most promising next-generation access network. To improve the energy efficiency in PON systems, the ITU-T standard for next-generation PON system introduced a new power management mode, so-called the Watchful Sleep mode. This new mode is expected to be operated on any TDM-PON or GPON variant. Although the sleep mechanism under the Watchful Sleep mode is well defined, its performance can vary greatly depending on the criteria used to start and/or terminate the power saving phase. In this article, we present a comprehensive analytical model for evaluating the energy efficiency of the watchful sleep mode using the Delayed Wakeup (DWU) mechanism. We then compare its performance with the Immediate Wakeup (IWU) scheme. Our analytical and simulation results highlight the accuracy of the presented model and prove its merits.