In this thesis, the dynamic bandwidth allocation algorithms are studied to support di-verse QoS requirements in EPON access network. we proposed a Q-DBA method which is bandwidth allocation method and suitable for EPON in the Chapter 3. The proposed Q-DBA method allocates bandwidth based on the priorities from the highest to the lowest step by step. Three classes of packets, voice ,video ,and data are considered. Voice packets are strictly delay sensitive, and video packets are delay sensitive. Besides, the dropping probability of voice or video packets is also required. Thus, Q-DBA sets the voice packets to be the first priority, and the video packets’ priority is changed from the fifth priority into the third priority when the video packets’ delay criterion will be violated at the end of next cycle. To sustain the video dropping probability, the priority of video packets can be raised to the second priority in further. Although data packets do not have any delay constraint, they still should not be sacrificed. The Q-DBA also raises the priority of data packets, which is from the sixth priority to the fourth priority when the waiting time of data packet exceeds the waiting bound. It can avoid the data packets from being in the starvation condition.
Furthermore, the bandwidth of the fiber link is totally allocated to make the system fully utilized.
that the Q-DBA has a better performance than DBAM has because the Q-DBA take some specific conditions into consideration. Observing the simulation, the simulation results also can be found that the QoS of voice packets can be fully guaranteed. The delay time of video packets is almost below the video delay criterion, and the dropping probability of video packets is also guaranteed even when the video packets are dropped. Besides, the data packets are transmitted without being in the starvation condition.
In chapter 5, we proposed an ONU assistant Q-DBA to improve the allocation of residual bandwidth in step 6. The residual bandwidth is allocated based on the queue lengths of all service classes. And the ONUire-allocates the granted bandwidth which exceeds the previous total queue occupancies which are reported at the previous timeslot to furthermore meet the queue conditions more realistically. Through the simulation results, the delay time of data packets is improved without violating the QoS requirements, voice delay criterion, video delay criterion, data delay bound, and the video dropping probability criterion.
In this thesis, the Q-DBA can support most of the system load without violating the QoS requirements. If the EPONs work with the combining Q-DBA and CAC mechanism, the QoS in a very high system load is still can be guaranteed. If the proposed Q-DBA method use some prediction mechanisms to allocate bandwidth in the step of residual bandwidth allocation, the performance may have improvement. In addition, with the development of WDM, the proposed Q-DBA method may be adapted to manage the resource in the EPONs, and customers can get the most benefits.
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Vita
Chin-Ya Huang was born in Nantou, Taiwan. She received B.E. degree in department of electrical engineering from National Center University, Taiwan, in 2004, and the M.E.
degree in the Institute of communication engineering in National Chiao Tung University, Taiwan, in 2006. Her research interests include resource management, performance analysis, and optical network.