A note on the potential energy savings by extending the average cycle times in Passive Optical Networks

This article proposes a mechanism to increase the energy efficiency of the upstream channel in TDM-base PONs. Essentially, the ONUs are encouraged to accumulate traffic and transmit data bursts just by increasing the cycle time values artificially. The guard time is enlarged to avoid the case where ONUs are queried by the OLT and have none or few packets to transmit, thus allowing more time to sleep until the next cycle time. This strategy has however the downside effect of a substantial increase in the queueing delay experienced by packets. We provide a basic analysis to maximise the power savings for a given average delay target experienced by the packets.