Design And Simulated Implementation Of Energy-efficient Bandwidth Allocation Algorithms In OFDM-PON

In recent years,the Internet changes rapidly with continuous development and innovation,meanwhile the traffic which requires high bandwidth presents explosive growth trend.Therefore,how to promote the development of next-generation network to the direction of high bandwidth,high rate and low energy consumption has become the focus in the academic and industrial communities.As a new kind of broadband access technology,Orthogonal Frequency Division Multiplexing-Passive Optical Network(OFDM-PON)not only supports highly efficient and flexible access among multi-users through multiple accesses,but also allows united scheduling between time domain and frequency domain,achieving elastic bandwidth allocation according to the bandwidth requirement.Therefore,OFDM-PON is recognized as one of the most promising technologies of next-generation broadband access.OFDM-PON system can provide higher bandwidth utilization and higher rate of information transmission compared with conventional PON systems.However,with the new problems emerging such as higher energy consumption and lower energy efficiency,the extensible capacity of network scale and traffic ability are seriously restricted.As a result,the research of energy efficient dynamic bandwidth allocation algorithm in OFDM-PON takes theoretical and practical significance for the development of green communication network.This thesis focuses on the research of energy efficient dynamic bandwidth allocation algorithm in OFDM-PON system.In previous works,some researchers have paid one-sided attention to improving system throughput or bandwidth utilization,even ignoring high energy consumption in the process of bandwidth allocation,and other researchers have considered imperfect model of energy consumption.To solve these challenging problems,we propose two comprehensive enegy efficient bandwidth allocation schemes.Firstly,according to the energy consumption that is influedced by the operation state of Optical Network Unit(ONU)which is the primary component of energy consumption in network,we propose the Three-Dimensional Dynamic Bandwidth Allocation based on ONU sleep mode(3D-DBA).In 3D-DBA,we deal with the three dimension bandwidth resource allocation,which includes time slot,subcarrier and bit allocation.We optimize the energy consumption of traffic related and traffic unrelated in OFDM-PON system.Meanwhile,the performance of bit error ratio(BER)of traffic and bandwidth requirements of each ONU should be guaranteed.Secondly,we further propose the Hybrid Energy-saving Dynamic Bandwidth Allocation based on adaptive link rate and ONU sleep mode(HE-DBA)in accordance with the energy consumption which is influenced by link rate.In HE-DBA,we deal with the hybrid energy-saving scheme.Our objective is to further minimize the energy consumption of traffic unrelated while guaranteeing the 'bit error ratio of traffic and bandwidth requirements of each ONU.The VC++ 6.0 software is employed to develop the simulation platform in order to make simulation experiment and evaluate the performance of proposed algorithms.A comparative analysis is made between the proposed algorithms and the previous algorithms.Simulation results demonstrate that the proposed 3D-DBA and HE-DBA algorithms gain the obvious advantages in reducing the energy consumption of OFDM-PON system,which may provide abundant theoretical guidelines and technological references for the development of OFDM-PON system in future.