Evaluating Energy Efficiency of ONUs Having Multiple Power Levels in TDM-PONs

A TDM Passive Optical Network (TDM-PON) proposes the use of sleep modes for Optical Network Units (ONUs) to maximize Energy Efficiency (EE). When an ONU manages a sleep mode, it needs to turn on and off some of its components based on communication requirements. Hence, an ONU ends up with multiple power levels. Existing analytical models for evaluating EE consider that an ONU has only two power levels. However, we have found in some literature where an ONU can have more than two power levels. In this letter we propose an analytical model to quantify the EE of an ONU having more than two power levels. We demonstrate the accuracy of the model by means of simulation under two different sleep interval deciding algorithms.

I. Introduction

The design of energy efficient networks is becoming an urgent necessity due to the rise of the energy costs and the associated ecological impact produced by ICT equipment. A common metric to measure the Energy Efficiency (EE) of a network is the bit/energy (b/J) [1]. This parameter allows us to quantify the EE of a network as well as to identify the improvement when applying a novel proposal [1]. Thus, in this letter we aim to develop a comprehensive analytical model to measure the energy consumption (and in conjunction, the EE) of an Optical Network Unit (ONU) with multiple power levels in a TDM Passive Optical Network (TDM-PON).