Unifying Sleep and Doze Modes for Energy-Efficient PON Systems.

The existing ITU-T PON specifications define two distinct ONU power management modes: Cyclic Sleep and Doze. This paper proposes a parametric extension allowing the Unified power management mode, in which an ONU periodically turns off both its receiver and transmitter, as in the Cyclic Sleep mode, and performs infrequent bidirectional handshakes, as in the Doze mode. The timely reaction to an external stimulus is ensured by periodic unidirectional handshakes when only the ONU receiver is turned on. The Unified mode thus combines the advantages of the two standardized power saving modes, and a system that supports the Unified mode can emulate either the cyclic sleep or doze behavior as a special case. Simulation results show the energy efficiency superiority of the Unified mode over either of the two standardized modes in general.