Optical Data Transmission Scheme Considering QoS in IP over WDM Networks

互联网流量的爆炸性增长推动了对波分复用（WDM）网络中新型高速传输和交换技术的需求。同时，各种多媒体业务的需求也在不断增长，如何保证WDM层的服务质量（QoS）是一个具有挑战性的问题。在本研究中，首先提出了一种新的WDM城域环网变长分组MAC方案。在该方案中，节点基于Unslotted IP和Backoff方案传输短报文。当节点发送长数据包时，该节点事先向其他节点发送用于预留的子载波信号，待该子载波信号返回到该节点后再发送长数据包。计算机仿真结果表明，该方案可以提高平均数据包延迟性能和吞吐量性能。其次，在光突发交换（OBS）网络中，进一步提出了一种基于突发丢弃（BD）技术的QoS控制方案。该方案由BD技术和分组编组技术组成。计算机仿真结果表明，该方案能够在不降低延迟性能的前提下，根据丢包情况提供不同的QoS。第三，为了在OCBS网络中实现与跳数无关的公平丢包概率，提出了一种新的突发丢弃技术，该技术根据跳数改变使用head - drop技术的概率。计算机仿真结果表明，与传统方案相比，该方案在不考虑跳数的情况下都能获得公平的丢包概率。第四，提出了一种同时考虑丢包概率和时延的QoS要求的新的QoS方案。该方案将通信量划分为4类，并自适应地结合了突发长度控制技术、偏移时间控制技术和BD技术3种控制技术。计算机仿真结果表明，该方案能够实现四类网络的QoS区分。最后，为了减少时间切片OBS网络中未使用的时隙，提出了一种通过分配数据突发来考虑新产生的头隙和尾隙的调度算法。计算机仿真结果表明，与传统调度算法相比，所提出的调度算法能够提高突发损失概率和吞吐量。少

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 … More 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