| Internet traffic has experienced an exponential growth in the past ten years, which is consuming more and more network bandwidth. Meanwhile, the emergence of critical delay-sensitive multimedia applications, such as video conferencing, video on demand, and interactive gaming, are not only swallowing up a large amount of network bandwidth, but also requiring quality of service (QoS). All these facts are imposing tremendous challenges on the underlying telecommunications infrastructure. Current telecommunication infrastructure consists of three major segments: the long-haul backbone network (LBN), the metropolitan area network (MAN), and the access network (AN). In this model, the role of the MAN is mainly to connect the clients on the AN to the LBN, which is also one of the most complicated networks in terms of application. Compared with the LBN and AN, the MAN has not developed significantly. Therefore current MAN has become a bandwidth bottleneck in today's telecommunications infrastructure.Optical packet switching (OPS) can provide high throughput, rich routing functionalities, and excellent flexibility. These advantages make it a promising candidate for the future MAN. Packet contention occurs when two or more packets are trying to leave the switch from the same output port on the same wavelength and at the same time. How contention is resolved will have a great effect on the performance of the networks. In general, there are three ways to resolve packet contentions, i.e., optical buffering, wavelength conversion and deflection routing. Both optical buffering and wavelength conversion require extra hardware and control software, whereas deflection routing can be implemented with extra control software only. Therefore, deflection routing is the least costly method among the three methods.In the part of MAN, several present technologies are analyzed and their respective pros and cros are compared first, including network topology, protocol layer and application scope. Then, the dissertation presents an OPS-MAN solution to the bandwidth pressure, network complicacy and quality of service. The OPS-MAN can provide a better utilization of the huge capacities from wavelength division multiplexing (WDM) transmission with finer granularity and bandwidth statistical multiplexing.The dissertation is orgnized as follows.In chapter 1, the status and perspective of MAN and OPS are introduced. And the architecture and functions of OPS node are described first, which is the core of OPS network. And on the base of that, key techniques involved in OPS network are introduced.In chapter 2 and chapter 3, the ring architecture and contention resolution scheme for the OPS-MAN are investigated. In this section, the existing techniques for MAN are studied and compared first. After overviewing and concluding the traditional architecture of MAN, we propose a new network ring architecture of MAN based on OPS, and the principles and advantages of the OPS-MAN are given. Further, we discuss the packet contention resolution scheme and present a feasible scheme. With the help of available network resource, we are able to reduce the packet loss rate (PLR) and support differentiated QoS. Simulation results demonstrate that a reasonable performance can be achieved in the proposed OPS ring architecture, and some key parameters are optimized through simulation.Chapter 4 concludes the paper. |
PDF Full Text Request