The Research Of Dynamic Bandwidth Allocation Algorithm For EPON Upstream

With the development of communication, and the appear of the new multimedia services, as well as bandwidth traffic is increasing to meet a variety of business needs, user’s requirements for bandwidth are also growing. Broadband optical access has a high transmission speed, long distance, good quality, strong immunity to electromagnetic interference, low maintenance costs, from the point of view of long-term development, the fiber should be the best choice of access network and the main way to address bottlenecks in the development of the telecommunications networkthe. EPON(Ethernet Passive Optical Network) is a point-to-multipoint optical access technology and system solutions, it is a way to solve the problem of the access between the telecom operators and the users which is positioned in what we oftensaid "the last mile" issue, the optical distribution network between the central office equipment and remote/user equipment contains only passive components or facilities, it does not include any active devices or equipment. Economic, low-cost combined with the technically perfect support for Ethernet, which is the biggest advantage of EPON as the preferred solution of optical access network. In addition, EPON system using the media is pure light, and the transmission scheme is transparent, so that EPON to ensure the security of information transfer as well as for future business expansion, so is considered to be the FTTH (Fiber To The Home) is one of the best solutions.EPON system in the uplink direction (ONU to OLT direction) uses TDMA (Time Division Multiple Access) access method, ont allocating each ONU a fixed allocation of uplink time slot, in order to avoid the upstream channel conflict, uplink bandwidth utilization and guarantee QoS(Quality of Service) between the business, designing an efficient, reasonable and fair allocation of bandwidth algorithm is of great significance,the algorithm can affect the entire EPON network properties.Major in Dynamic bandwidth allocation, this paper first introduced the paper research background and significance, analysis of the current access network technology, and development status, and described the structure of the EPON systemas well as the basic working principle, focusing on analysis of the multi-point control protocol (multi point control Protocol, the MPCP); in the next part, existing DBA algorithms:IPACT and CPFCT are introduced, and improved them with the ability to meet the demand of QoS, after analyzing the characteristics of the two classical algorithms, advantages and defects, and on this basis, a modified DBA algorithm has been proposed, simulation results show that the overall performance of the new algorithm is better than the two classical algorithms. Then in the conditions of different system configurations, using the IXIA network tester to verify the validity of the algorithm on the actual device. In the end, task of the paper, related conclusions and the expectation are summarized.