Research On Dynamic Bandwidth Allocation Scheme In EPON

In recent years, with the growth of the network service and the network's transmission ability, and the upgrade of the backbone and the high speed LAN,the access network was becoming the bottlenect of the communication network. Based on the convergence of low-cost Ethernet equipment and low-cost fiber structure, so Ethernet Passive Optical Network(Abbr. EPON) appears to be the most promising solution for the next-generation broadband access network. EPON is a multi-Point to Point network and all Optical Network Unit(Abbr. ONU) share the same upstream channel according to the manner of Time Division Multiplexing Access(Abbr. TDMA). so bandwidth allocation is one of the critical issues in EPON system. In order to guarantee the QoS of different services and high-bandwidth utilization, the reasonal bandwidth allocation algorithm is necessary. Based on the analysis of saveral bandwidth allocation algorithms, a new algorithm is proposed and is advanced ,which is proved by theory and caculation.Firstly,this paper introduces the development of access network,the history of EOPN,and the advantages of technology. Secondly, the architectures and breif manners of an EPON system have been given. Dynamic Bandwidth Allocation(Abbr. DBA)algorithm presents statistical multiplexing technology in the upstream channel,access mechanism and multipoint control protocol(Abbr. MPCP),defined by the IEEE 802.3ah Task. Several existing DBA algorithm,and proposed the advantages and disadvantages. In view of this situation, this paper proposed a new DBA algorithm. In order to improve the fairness of bandwidth allocation in the EPON, a DBA algorithm proposed by this paper introduces the methods of inter-ONU scheduling and intra-ONU scheduling. Meanwhile, to meet the demanded bandwidth of heavily-loaded ONUs, the algorithm uses the excessive bandwidth of lightly-loaded ONUs and which can significantly improve bandwidth utilization. what's more, the paper analysises the fairness of DBA algorithm.Finally,the summary and prospect are given in this paper.