The Dynamic Bandwidth Allocation In Ethernet PON

These years, with the fast development of communication industry and increasing requests for bandwidth, network transmission ability has been improved a lot. However, the access networks have not changed much, have been the bottleneck of the whole network. The Ethernet PON(EPON) system has many advantages. It naturally has been one of the best technologies in the next generation access network.In this thesis, we first introduce the evolution of EPON multiple access technology, and study the theory architecture and key technologies of EPON in details. Effective bandwidth allocation schemes are very necessary due to requests of higher upstream bandwidth utilization and ensuring QoS of different services. It is important to design a fair,high-performance and supporting diferent service QoS dynamic bandwidth allocation algorithm.This thesis analysis some current bandwidth allocation schemes, point that there are many challenges are left, and further study their resolutions. And represent a new DBA algorithm based on the previous work.In the new algorithm, so as to guarantee the fairness both between and in the ONU, bandwidth allocation is classified into two classes: intra-ONU bandwidth allocation and inter-ONU bandwidth allocation. The new algorithm also puts forward the differ-services idea to guarantee the QoS of the real-time service. And division the total bandwidth into different grades, sets aside a part of the total bandwidth to support the fixed grant bandwidth of the real-time service, while the surplus bandwidth is utilized by the other services. Besides that, we bring forward a reallocation mechanism to surplus bandwidth among over-loading ONUs.At last, we use the network simulation software called OPNET to construct the model of the new dynamic bandwidth allocation and carry out a series of simulation experiments. The simulation show that the new dynamic bandwidth allocation algorithm performs better in the delay and fairness aspects.