| With the rapid increase of IP-based traffic, such as peer-to-peer (P2P) application, video conference, IPTV and so on, passive optical network (PON) is being the first choice in wide band access network. Compared with EPON, GPON is becoming more and more important as it can support many different rate classes, guarantee of full-services QoS, high survivability and efficiency.Firstly the background, the frame formats, the operate mechanism of GPON technology, its device structure of OLT and ONU and the DBA algorithm were described based on ITUT-G.984 protocol serials. Then the DBA mechanism was been researched deeply as it presents a key issue for providing efficient and fair utilization of the GPON upstream bandwidth while supporting the QoS requirements of different traffic classes. An improved DBA algorithm named C-DBA has been purposed in this paper. The biggest difference between this algorithm and the others is that it was based on 3 kinds of T_C0NTs. Whereas the others are based on 5 kinds of T_CONTsA testbed was constructed in order to prove its performance. The architecture of this testbed and how we designed it were introduced in detail. Based on the performance standards of DBA algorithm we designed the simulation scenarios. The simulation results showed that the bandwidth efficiency of this algorithm was very high and the service delay was low. So this algorithm can better guarantee the QoS requirements of different traffic classes. |
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