A Research On Several Key Problem In Metro WDM Network-Theory, Experiment And Applications

The Wavelength Division Multiplexing (WDM) technology has achieved wide applications in the field of Optical Network (ON). It provides an easy scheme to satisfy the high-capacity requirement of long-haul ON. However, the use of WDM technology in the current market of Metropolitan Optical Networks (MON) is not obvious yet due to limitations in the cost of WDM components, types of access services and need of the market. Thus, to accelerate the use of WDM in MON, attentions must be paid to both the advantage of WDM performance and the competitive potential of its cost. The present thesis focuses on some primary problems in Metropolitan WDM (Metro WDM) Networks, and provides the corresponding solution to the issues of cost, traffic, protection and architecture in Metro WDM networks.The sensitivity of the cost is the most important factor of a Metro WDM network. We study the cost of Metro WDM in two aspects in Chapter 2. For the aspect of components, a Bidirectional Optical Add-Drop Multiplexer (BOADM) using fiber gratings and circulators is designed, and is cheaper, simple and appropriate compenent for Single-Fiber Bidirectional Ring Networks (SFBRN). For the aspect of network, after study the traffic-grooming problem and the cost of WDM ring networks, a layered network with a multi-HUBs is presented to reduce the total number of the network ports. Furthermore, a novel wavelength allocation algorithm based on "circle construction" is proposed. The optimal objective of this algorithm is to minimize the number of wavelengths used in network.To realize the multi-service transport ability in Metro WDM networks, we have built a platform based on SDH/WDM in Chapter 3.The platform composes of SDH&WDM equipments at two nodes which connected by only one 50km SM fiber. Some VLAN modules are inserted, and the SDH forms a single-fiber bidirectional LAN to transport IP service. Some coders/decoders of video are connected to the modules to finish the video service transport.To satisfy the need of Metro WDM survivability, two types of protection strategies, namely, Share-Fiber Virtual-Path Protection and Single-Fiber Bi-directional Ring Networks DNI Protection, are given in Chapter 4. The former is suitable for a complicated ON such as a mesh network using the Optical Ring Protection. The latter is often employed for BOADM in Single-Fiber Bidirectional Ring Networks.In Chapter 5, after investigating the status and needs of transport network in a university, we propose a new WDM network architecture. The design is based on WDM ON, and includes the principle of design, layering and protecting of network, composing of network's equipment, structure of nodes and realization of some services, etc. It gives an integrated exmple which is suitable for other Metro WDM networks in the future.Till now, no standard exists in how to realize the traffic transportation, select the technology and the direction of construction, and program the layout in a Metro WDM network. Through the study of the course, the characteristics and the problems Metro WDM networks have faced, we synthesize the needs in capacity, reliability, flexibility, and multi-service transport ability of networks, and present some practical solutions for them to speed up the use of WDM in metropolitan in the future.