Study On The Dynamic Bandwidth Allocation Schemes Of EPON Upstream Channel

In recent years, there are great changes in the backbone of communication networks, but fewer in the access network. As the fiber has the advantages of broad bandwidth, huge capability, powerful resisting jam ability etc, it is very suitable to be the transport media of high-speed broadband network. Thinking of the actuality of the IP network and the ability of PON transport, EPON will be one of the main solutions to implement future broadband access network, even be the final technology to implement FTTH. Now, the EPON standards are still discussing by IEEE.Dynamic bandwidth allocation is the key technology of EPON, which has great significance to improve QoS, reduce packet delay and packet loss rate. Now, the researches on EPON frame format, bandwidth allocation algorithm and performance analysis, and how to realize QoS, are now becoming the hot spots in home and abroad.The research is mainly focused on the dynamic bandwidth allocation schemes of EPON upstream channel. The new results are as follows: discussed some key technologies of EPON, and proposed a scheme of access system similar to token ring for distributed EPON. A mathematic model of EPON upstream channel is analyzed based on the discussion of the existing bandwidth allocation technologies of EPON. And a scheme of dynamic bandwidth allocation based on fixed length is also put forward. In order to adapt to the variable length of Ethernet frame,an improved scheme based on IPACT is put forward too. Finally proposed an improved WFQ and WRED arithmetic to guarantee the QoS of EPON based on the analysis of QoS model and the concrete control mechanism.