| Budget Amount *help |
¥3,500,000 (Direct Cost: ¥3,500,000)
Fiscal Year 2004: ¥1,700,000 (Direct Cost: ¥1,700,000)
Fiscal Year 2003: ¥1,800,000 (Direct Cost: ¥1,800,000)
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| Research Abstract |
The explosive growth of Internet traffic is driving the demands for new high-speed transmission and switching technologies in Wavelength Division Multiplexing(WDM) network. Also, the demands in various multimedia services are increasing and it is the challenging issue how to guarantee Quality of Service(QoS) in WDM layer. In this research, at first, a new MAC scheme for variable length packet in WDM metro ring network has been proposed. In the proposed scheme, a node transmits a short packet based on Unslotted IP with Backoff scheme. And when a node transmits a long packet, the node transmits a subcarrier signal for reservation to other nodes beforehand and can transmit a long packet after the subcarrier signal returns to the node. By computer simulations, it is shown that the proposed scheme can improve the mean packet delay performance and throughput performance. Secondly, a new QoS control scheme by using Burst Dropping(BD) technique in Optical Burst Switched(OBS) network has been p
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roposed. The proposed scheme consists of BD technique and the packet arrangement technique. By computer simulations, it has been shown that the proposed scheme can provide QoS differentiation in terms of the packet loss without degrading the delay performance. Third, in order to achieve the fair packet loss probability regardless of the number of hops in Optical Composite Burst Switching(OCBS) network, a new burst dropping technique has been proposed that changes the probability of applying the Head-Dropping technique based on the number of hops. By the computer simulation, it is shown the proposed scheme can achieve the fair packet loss probability regardless of the number of hops compared with the conventional one. Fourth, a new QoS scheme has been proposed that takes the QoS requirement for both the packet loss probability and the packet delay into account. The proposed scheme divides traffic into four classes and combines three control techniques, the burst length control technique, the offset time control technique and BD technique according to classes adaptively. By computer simulations, it is shown that the proposed scheme can provide QoS differentiation between four classes. Finally, to reduce unused timeslots in Time Sliced OBS network, a new scheduling algorithm has been proposed that considers head gap and tail gap newly generated by assigning a data burst. By computer simulations, it is shown that the proposed scheduling algorithm can improve the burst loss probability and the throughput compared with the conventional one. Less
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