| Recently, with the growth of Internet and broadband applications, FTTH (Fibre to the Home) become the objective of access networks and is accepted as a kind of excellent integrated solution for access network. Among kinds of optical access network techniques, GPON supports multi-speed rates, full-services QoS, robust network, high efficiency and other advantages, and considers the suggestions of SPs (service providers) at the same time. GPON is regarded as one of the best choices for broadband access network in the future. So it is very important to research GPON and its key technologies especially.In order to achieve optical access network and AON, the research of GPON's key technologies is important. The foundation of this thesis is product R&D of telecommunication equipment provider. We study the development of the standard, considering synthetically some factors including development of optical network, demands of ISP and technique capability. In order to realize commercial GPON system, some key issues must be solved, which include user security, safeguard technologie, TDM manage, GEM encapsulation, ranging, fast outburst synchronization, media access control, and so on.Here we study three key technologies in GTC layer in GPON, the main content are:(1)It presents an analysis of standard, and suggests that GEM encapsulation should be adopted.(2) It investigates ranging method, which measure the logical distance between each ONU and its associated OLT and determining the transmission timing such that upstream cells sending from different ONUs on the same ODN do not collide.(3) It discusses some dynamic bandwidth allocation algorithms which have been put forward, and point out their advantage and disadvantage.(4) A new dynamic bandwidth allocation algorithm is presented with its support differentiated services over GPON and it follows the standard.(5) A GPON model was developed and implemented on OPNET Modeler, the result validates the capability of new algorithm. |
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