Research Of Energy Saving Strategy In Passive Optical Networks

The energy saving and consumption reduction for the access network is a hot issue both in current academic and industrial circles.Passive Optical Network(PON)has significant advantages such as high capacity,low loss,cheap cost,and transparency to services,etc.It is one of the preferred technologies for broadband access networks.At the same time,the optical wireless hybrid broadband access network(HOWBAN)combines not only the advantages of the optical access network,but also the advantages of high flexibility,easy deployment,and support for mobility of wireless network.Therefore,it is one of the promising solutions for future broadband access technology.This thesis presents a comprehensive and in-depth research on the energy-saving issues in PON and HOWBAN system by theoretical analysis and simulations.Firstly,this thesis briefly describes some fundamental priciples,network architecture,network element device,and key techniques of PON and HOWBAN,etc.Aiming on the PON and the HOWBAN implementation scenarios,the existing energy-saving schemes are analyzed in detail.Both the advantages and disadvantages of the existing energy-saving schemes are compared and analyzed from the aspects of working principles and performance analysis.This thesis proposes an energy-saving scheme based on OLT buffering.The improved scheme introduces a modular energy-saving technology with a buffer located at the OLT to cache data from the core network.The OLT dynamically grants bandwidth to each ONU and controls the transmission and reception status of different modules in the ONU.Theoretical analysis and simulations result show that the improved scheme can save 75% energy compared with the traditional energy-saving scheme.When the downlink load is low,the average downlink delay of the downlink packet is significantly improved compared with the traditional energy-saving scheme.Additionally,this thesis proposes an optical and wireless hybrid energy-saving scheme based on load transfer for a typical commercial and residential hybrid building scenario.The improved scheme puts the low-load network nodes into a sleep mode,and transfers the part of the load to other active nodes through re-routing.Mathematical derivation and experiment show that the scheme can effectively improve the average energy-saving efficiency compared with the traditional scheme.When the household users account for 25% and 50% of the total users,respectively,the average energy efficiency is increased by about11.3% and 20.4% respectively during the day when the total load of the users is large.