Optimization And Analysis Of Dynamic Bandwidth Allocation Algorithms In Ethernet Passive Optical Networks

With characteristics of low cost, low overhead and flexible network structure, EPON is considered as one of the best solution in FTTH. In practice, based on tree topology, the uplink bandwidth of ONUs must be shared by TDMA. In order to ensure the system bandwidth utilization and fairness between ONUs, dynamic bandwidth allocation algorithm is needed, which is one of the key technologies determining the performance of EPON, for solving the EPON upstream bandwidth sharing problem. MPCP protocol determined in IEEE802.3ah is an important bridge for communication system implementation, providing the framework and the necessary conditions for bandwidth allocation algorithm.The topology of EPON and the important role of MPCP protocol are focused. The characteristics and topology of EPON system and the development situation of dynamic bandwidth allocation algorithm are introduced, as well as the structure of MPCP protocol which has an important role of in EPON system communication. On the basis, the improvements of existing dynamic bandwidth allocation algorithm are presented, from three aspects:the QoS, bandwidth utilization and polling methods. Firstly, services are divided into three classes, for which the principle and algorithm of bandwidth allocation are discussed and improved. Secondly, the principle and algorithm above are improved further, and grouping of current LLID is proposed, according to which bandwidth is allocated. In order to further enhance the bandwidth utilization, and finally improve bandwidth allocation, bandwidth allocation principle based on the prediction is suggested.Based on the improved algorithm, the OPNET simulation platform is described in detail. The EPON network model is established, which is used to simulate the improved algorithm, and results are obtained. Based on the analysis, the feasibility and effectiveness of the algorithm are proved. The improved algorithm can reduce the average delay, improve the network bandwidth utilization, and can satisfy the needs of multi-service network.