Energy Efficiency in Ethernet Passive Optical Networks (EPONs): Protocol Design and Performance Evaluation

摘要

As concerns about energy consumption grow,the power consumption of the EPON becomes a matterof increasing importance. In respect of energy efficiency,the current standard has no management protocols aimingto reduce power consumption in EPONs. In this paper,we propose an Energy Management Mechanism (EMM)for downlink EPON systems. The proposed mechanism isdesigned to enhance the standardized control scheme inEPON with the objective to increase energy efficiency whilesatisfying diverse QoS requirements. The main idea is toput an Optical Network Unit (ONU) into the sleep modeand determine a suitable wakeup time scheduler at theOptical Line Terminal (OLT). A generic EPON system isconsidered, which is composed of an OLT and several ONUsthat are EMM enabled. An energy consumption optimizationproblem aimed at saving energy is proposed and twoheuristic sleep mode scheduling policies are addressed tosolve it. The scheduling algorithms are tightly coupled withthe upstream bandwidth allocation and downstream transmissionscheduling together through an integrated approachin which awake time in ONUs is minimized. There is atrade-off decision between maximizing the power saving andguaranteeing the network performance at the same time.Simulation results show that an EMM-based EPON withwell designed scheduling disciplines is essential to achievingsignificant energy saving while meeting the delay constraint.