【作者】 刘心；

【导师】 纪越峰；

【作者基本信息】 北京邮电大学 ， 电磁场与微波技术， 2009， 博士

【摘要】 数据业务的爆炸式增长及其在通信业务中所占比重的不断增加使通信网络中业务流量的特征发生了明显的变化。流量相对平稳的话音业务在通信业务中的主导地位已经完全被具有流量突发性的数据业务所取代。同时,IPTV,视频点播,多方视频会议等新业务的产生以及普及也使得点对多点的组播业务在整个通信业务中所占的比重显著增加。承载业务的这些巨大变化使光网络技术的发展已经由最初的以技术驱动为主逐步转变为以业务驱动为主。如何在光网络中更灵活地实现突发数据业务的全光传送以及如何更高效地实现组播数据的全光分组转发已成为近年来光网络数据传送技术领域研究的重要内容。本文从通信业务对传送网络的需求出发,对突发数据光传送和分组模式光组播的核心机制与关键技术进行了研究,具体包括以下内容：(1)在突发数据光传送技术方面,本文通过数学分析、计算机仿真及硬件实验等多种手段,对基于声光可调谐滤波器(AOTF)的突发模式光传送技术进行了性能分析和实验验证。该技术利用AOTF的微秒级快速可调谐技术特点实现了WDM环网中光突发数据包的快速调谐接收。它的核心机制是通过令牌轮询机制有效规避网络中光突发数据包之间的资源竞争问题,进而实现面向业务突发性的灵活、可靠的全光数据传送。从分析及实验结果来看,令牌轮询机制下的突发模式全光传送技术虽然能够在一定程度上提升网络的整体效率以及灵活性,但最大突发包长度和最小突发包长度等参数的设置、网络承载业务量的变化以及网络规模的大小等都会对网络的整体性能产生直接影响。文中给出了各个参数与网络性能之间明确的量化关系,为实际网络设计以及性能评估提供了有效参考。(2)针对令牌轮询机制下的光突发传送技术在空间重用、服务质量分级等方面存在的不足,本文结合弹性分组环技术与突发模式光传送技术,创新性地提出了面向数据业务多样化性能需求的新型弹性突发环网络技术。它将弹性分组环技术在空间重用、服务质量分级等方面的诸多优势扩展到多波长网络中,实现了面向数据业务突发性和多样性的新型光传送技术。弹性突发环的核心机制是利用突发模式光传送技术实现数据业务的传输,并通过光电二级缓存机制解决突发数据包在传送过程中的资源竞争问题。它采用基于优先级的仅目的延迟控制协议,通过对不同等级业务设置不同的额外偏置时间并采用不同的资源竞争解决机制,实现弹性突发环灵活的服务质量策略,以此满足网络所承载的各种业务对传输性能的多样化需求。文中分别介绍了弹性突发环的传送机制、缓存机制、节点结构、控制机制以及服务质量策略等,并通过计算机仿真,对其网络性能进行了研究。仿真结果表明,弹性突发环技术能够有效地实现多种不同等级业务的传送并保证他们的服务质量。(3)在分组模式光组播技术方面,本文针对传统并行模式全光分组组播技术代价高、灵活性差、组播成功率低等问题,创新性地提出了新型的串行模式全光组播机制。该机制的核心是利用光开关可控的全光环路实现对光组播数据包的缓存,并通过光信号在缓存器中的循环以及环上的光功率分路器和功率补偿器件的复制及功率补偿实现光组播数据包的串行输出。与并行模式组播机制相比,它一定程度上缓解了组播数据包对输出时间的限制,部分地实现了光缓存的功能,有效提高了光组播数据包的转发成功率。此外,本文通过硬件实验对该机制的可行性进行了验证,并从实验结果中进一步分析了该机制存在的噪声积累、额外组播延迟以及对输入组播数据流的限制等问题。(4)针对串行模式组播机制的额外时延及噪声积累等问题,本文提出了基于二级缓存结构的改进型混合模式全光组播机制。它通过二级缓存机制减少组播数据包的在全光环路中的循环次数,降低因光信号循环而产生的噪声积累。同时,它通过串行模式与并行模式的结合,降低组播数据包的额外组播时延以及对输入组播数据流的限制。利用计算机仿真,本文对并行、串行及混合模式全光组播机制在光分组交换网络中的性能进行了分析和比较。从仿真结果中可以看出,相比于并行和串行模式全光组播机制,混合模式全光组播机制能够达到最高的组播成功率及最大的组播传输速率,具有最好的网络性能。(5)为进一步提升全光分组组播技术的服务质量,本文提出了一种用于光标记交换网络技术的基于延迟资源预约的全光串行组播机制。它充分利用光标记交换网络技术的特点,通过延迟资源预约,在无缓存的条件下消除光组播数据包的资源竞争问题,并通过与组播包调度算法的有机结合,实现了具有严格服务质量保证的组播业务全光转发机制。更多还原

【Abstract】 In existence for over a decade now, optical transport networks have traditionally been designed for voice transmission based on time division multiplexing (TDM) technology. At that time, voice traffic was significantly more important than data traffic. As a result, synchronous optical network/synchronous digital hierarchy (SONET/SDH) became the dominant standard on these networks. Those technologies have been able to meet the initial requirements of TDM services quite adequately and today, most of them are based on SONET/SDH technology.With the explosion in the demand for bandwidth for data transmission, it became quite clear that the traditional SONET/SDH networks need to be reengineered to handle data traffic in a more efficient way. To this end, this dissertation starts off from the performance requirements of the services to the carrier networks and mainly focuses on the research on the services-oriented dynamic optical network technologies. The detailed contents can be divided into two parts:one is the novel optical network architecture and the transport technologies towards the’bursty’nature of the data services and their various performance requirements; the other is the novel packet-based all-optical multicasting technologies and their implementations in the dynamic optical networks. The contributions of this doctoral dissertation mainly can be summarized as follows.1.The research on the acoustic-optic tunable filter (AOTF)-based fast tunable burst receiving technology for the WDM-based ring networks. It employs the AOTFs to realize the fixed transmitter and tunable receiver (FTTR) scheme and adopts the round-robin token scheme to avoid the bursts’contentions. Both numerical and simulated modeling techniques were applied to analyze the influence on the performance of this technology caused by the parameters, such as the minimum and maximum burst length, the circumference of the ring, and so on.All the results show that to design a high-performance token-based burst-mode WDM ring network, not only the common parameters, such as the number of nodes and wavelengths, and the circumference of the ring, but also the special parameters, such as the minimum and maximum burst length, and the offset time should be taken into account.2. The research on the next-generation WDM-based carrier-grade Ethernet. This dissertation extends the concept of the Resilient Packet Ring (RPR, IEEE 802.17) to WDM networks and proposes a novel network architecture called Resilient Burst Ring (RBR). This architecture inherits all the best features of RPR, provides a burst-mode data transmission scheme through a two-sublayer (optical and electronic) hierarchy, and realizes the WDM-supported ultra-high-speed Ethernet with scalability and reliability. RBR adopts a two-layer buffering scheme to resolve the contentions of optical burst packets and provides three different data transmission modes. With the proposed Priority-Only-Destination-Delay resource reservation control protocol, RBR can provide a flexible QoS strategy to implement the transmission of all of the applications and services in existing networks.3. The research on the novel all-optical multicasting schemes and their implementations in the dynamic optical networks. To increase the multicast success ratio, a serial-mode and a hybrid-mode optical multicasting scheme are proposed in this dissertation. The serial-mode multicasting scheme uses a separated multicast module to realize the storage, duplication and serial export of the input optical multicast packets. It can partly perform the function of the optical random memory and, therefore, improve the performance of multicasting in the all-optical networks. The hybrid-mode multicasting scheme is proposed to reduce the signal impairment and the extra delay caused by the serial-mode multicasting scheme. It combines the parallel mode and the serial mode multicasting schemes, realizes the duplication and storage of the input optical multicast packets, and exports multiple copies each time. By computer simulations, results show that the hybrid mode multicasting scheme had the best performance in the optical packet switched networks. Besides, this dissertation also does some simulated and experimental researches on the performance of the serial-mode multicasting scheme and proposed a delayed resource reservation scheme for delivering multicast sessions in the labeled optical packet switched networks.With the delayed resource reservation scheme, contentions can be avoided and steady data transport pipelines for multicast sessions can be established from the source node to all the destination nodes. Consequently, QoS for those multicast sessions can be guaranteed effectively in the labeled optical packet switched networks.更多还原