| With the ever increasing demand for bandwidth intensive applications like video-on-demand, high-definition television (HDTV) , interactive television services and Internet telephony, the first mile network, referred to as the last mile network in the earlier stages of its development, has proven to solve the bottleneck often experienced between users and the central office.In order to resolve this bottleneck, the IEEE 802.3ah Task Force for Ethernet in the First Mile (EFM), developed the Ethernet Passive Optical Network (EPON) that resolves this bottleneck by providing the user with a fiber optic link to the central office that has many advantages, such as nearly infinite bandwidth, low cost, easy installation and a saving of the need for powered components in the signal path from the user to the switch and so on. Due to its low cost and high throughput, the Ethernet passive optical network (EPON) has been considered as an attractive solution to next-generation broadband access networks.But it's a challenge for EPON designers. However, designing an efficient bandwidth allocation algorithm is a critical issue in EPON. In this thesis, various dynamic bandwidth allocation (DBA) algorithms for EPON systems are first reviewed, and the analysis of advantages and disadvantages of each algorithm that is given. On this basis, Aiming at the upstream TDM mechanism in EPON system, this paper presented a novel dynamic bandwidth allocation algorithm (PEM-DBA) which supports traffic estimation and bandwidth pre-allocation. The simulation result shows that compare with others algorithms our algorithm gives preference to higher-priority traffic as well as reduces the time delay of the data and higher bandwidth utilization. |
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