Epon System Upstream Bandwidth Allocation Algorithm And System Architecture

These years, with the fast development of communication industry, network transmission ability has been improved a lot. Backbone network and high speed LAN are expected to be continuously updated with increasing requests for bandwidth of users. However, how to design the access network connecting backbone network and LAN becomes the design bottleneck of the whole network. Although, current broadband access methods, such as xDSL, HFC and cable modem, have provided higher bandwidth and are widely used, they still can not satisfy users'requests and have not the ability to provide enough bandwidth and QoS for new networks'services such as video meeting, VOD, VOIP and so on. Ethernet network is a very popular network with low cost and high bandwidth. Meanwhile, optical network also has low cost and high capacity. Consequently, EPON system, which is a passive optical network based on Ethernet, has become one of the best technologies in the next generation broadband access network. Allocation schemes of the uplink bandwidth have attracted much attention in the EPON system owing to the topology structure of ONU sharing bandwidth in the uplink. Effective bandwidth allocation schemes are very necessary due to requests of higher uplink bandwidth utilization and ensuring QoS of different services. This thesis analyses current bandwidth allocation algorithms, and provides a new dynamic bandwidth allocation scheme, which has fixed period and utilizes cyclic polling, based on the self-similarity character of network traffic. It is showed by simulation results that the scheme ensures the QoS of different services with higher priority and can improve uplink bandwidth utilization. At the same time, as one new switch equipment. EPON system has not achieved the total standardization of its function and structure, and is expected to have a further research. According to the main function and structure of EPON system, this thesis clearly divides EPON system into several function blocks, and discusses the function, structure, work flow and theory of each block seperately. Furthermore, this thesis has accomplished some research on function and structure of EPON system.