Design And Implementation Of EPON Optical Line Terminal

Along with the rapid development of communication technology, users requirements of bandwidth become higher and higher. The Ethernet Passive Optical Network (EPON) based on mature Ethernet technology uses point-to-multipoint structure, passive optical transmission, and provides a wide range of business on the Ethernet. It combines the advantages of passive optical network technology and Ethernet technology, has following characteristics: low-cost, compatibility, maturity, easy to maintain, operational flexibility and so on. It becomes one of the best schemes of the next generation broadband access network.The thesis aims at satisfying customer, focuses on implement the best performance and operation of EPON system, and studies and designs the Optical Line Terminal (OLT), including OLT architecture, main service model, Element Management System (EMS) and so on. It also elaborates the research and improvement of uplink bandwidth allocation algorithm. The contents of the studies of this thesis are as follows:Firstly, this thesis starts from the architecture of EPON, analyzes the working principle and technical features of EPON system, determines the requirements and system layout of OLT.Secondly, according to China Telecom's technical requirements of EPON equipments, this thesis proposes a set of OLT architecture, service model, and the implementation of main module. The main module of OLT equipments includes power supply module, OBC module, IWF module, EPON module and so on. Service models mainly include HSI service and IGMP service.Thirdly, according to the analysis of various kinds of network management protocol, software architecture and development tools, this thesis implements a OLT device Element Management System (EMS) of EPON, which uses Browser/Server structure and MVC design pattern. This system is based on Flash, PHP and Java, and includes configuration module, performance module, security module and so on. Clients can access network elements conveniently by using browser. Every module of this system is independent and has a strong portability.Finally, this thesis proposes an improved DBA algorithm which is applicable to EPON system of industry network service based on analyzing the traditional DBA algorithm, to make sure that supervisory and alerting signals are transmitted in time. Meanwhile, this algorithm chose fixed cycle polling other than interleaved polling for saving unnecessary bandwidth. Simulation results of OPNET show that the improved algorithm has higher bandwidth utilization, lower service delay, and no light-load penalty.