| Nowadays,as an important access network technique,1Gbit/s Ethernet Passive Optical Network(EPON)has been massively deployed by service providers,The next generation of passive optical network 10 GEPON technology become the research hot spot.MAC layer is the data link layer of 10 GEPON system,controls access of the physical transmission medium.in which complete shared network point to multi-point media access and control,is the most core technology of the system.Therefore,the key technology of MAC layer in 10 G EPON system is researched deeply.In this paper,the development of access network and its related technologies are introduced first.After briefly compared the technical characteristics of 10 GEPON and EPON,the research status of dynamic bandwidth allocation is expounded.Then,the structure of 10 GEPON system and its working principle are introduced.The key technology of MAC layer in 10 GEPON system is analyzed deeply.This paper analyzes the process of ranging and synchronization of MAC layer in detail,and introduces the existing time-tag ranging method,showing its superiority and feasibility.Secondly,this paper focuses on the dynamic bandwidth allocation technique in the MAC layer.Based on the existing algorithms,a T-DBA algorithm with high bandwidth utilization and fairness between ONUs is proposed.The algorithm adopts the advance authorization mechanism of“how much need,how much allocate” for the high priority service,the transmission strategy of “first arrived,first send”is used..For medium and low priority services,a token-conversion algorithm is adopted.In the premise of improving the bandwidth utilization,the fairness of ONU group is ensured.The simulation model is established by OPNET.The simulation results show that,The T-DBA algorithm can improve the bandwidth utilization of the system and reduce the average packet delay of the three services,ensuring the QoS of the whole 10 GEPON system under multi-service and multi-priority effectively. |
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