Research Of Two Level Dynamic Bandwidth Allocation Algorithm Based On QoS On EPON Access Network

In recent years, there are great changes in the backbone communication networks, but little progress in the access network.The fiber has the advantages of broad bandwidth,huge capability,powerful interference rejection etc,which suits very much as the transmission medium of high-speed broadband network.Thinking of the actuality of the IP network and the ability of PON transport,EPON(Ethernet passave optical network) will be one of the main solutions to implement future broadband access network, even be the final technology to implement FTTH.Upstream access and dynamic bandwidth allocation which have important meaning in raising the service quality of EPON and reducing packet delay and packet loss rate,is one of key crucial technologies of EPON system. Now, according to function,the structural and bandwidth allocation algorithm, performance analysis of EPON,and how to realize QoS guarantee are becoming domestic and international research hot spots.The research is mainly focused on the dynamic bandwidth allocation schemes of EPON upstream channel.Firstly this thesis introduced the development of the access network, some kinds of comparison of optical access network.Then from definition of EPON system,we illuminate structure of EPON system and operation principle,up and down frame,Analyze the characteristics and key techniques of EPON.Then, mainly Analyze EPON on upstream access technology and bandwidth distribution strategy.Analyzing in detail the characteristic of various bandwidth distribution schemes, we put forward a kind of two level dynamic bandwidth allocation scheme based on credit degree,divided dynamic bandwidth as Intra-ONU level and Inter-ONU level,adopt allocation scheme based on credit degree in Intra-ONU level and adopt different transmission bandwidth from different flows in Inter-ONU level. We establish corresponding maths model and analyze its function. Our new algorithm combining with MPCP protocol and GRANT/REPORT mechanism, finish access control between OLT and ONU. This algorithm can dynamically adjust transmission window size and decide the maximal size of the window. It is more efficient in utilizing the upstream bandwidth resources.In this paper, we first establish EPON network using advanced network simulation tool OPNET on upstream channel MAC control sub-layer based on TDMA model. On the foundation of basic model,we increase new algorithm of development bandwidth allocation.All the emulations are based on the finite state machine model.Comparing with other traditional algorithms,...