A hierarchical wavelength assignment algorithm with wavelength re-use for routing within WDM networks.

摘要

The use of optical fiber as a transmission medium for long distance high speed communication has become commonplace throughout the world. This has come to be almost a necessity as wide area computer networks and the Internet continue to grow in size and scope. Optical fiber has with it an extraordinarily large bandwidth capacity that has yet to be fully realized by any network protocol. One of the major obstacles to utilizing the terahertzs of bandwidth available in the optical fiber is the lack of electronic devices capable of switching at the extremely high rate of terabits per second. Current state of the art electronics are only capable of switching at rates of tens of gigabits per second.; Wavelength Division Multiplexing (WDM) has emerged as one of the most promising optical networking technologies for harnessing the bandwidth available in the optical fiber. By dividing the optical spectrum into multiple operational wavelengths, WDM attempts to multiply the amount of data that can be transferred with today's electronics. The implementation of WDM brings with it a new set of engineering problems not typically associated with single wavelength optical transmission systems. These problems include the development of rapidly tunable coherent light sources for use as transmitters and equally rapid tunable devices for optical receivers. Moreover, the use of multiple wavelengths for data transmission on the same optical fiber requires the development of wavelength switches capable of handling the enormous amounts of data that multiple optical channel networks experience.; Perhaps just as important as the previously mentioned hurdles to realizable high capacity WDM network is a wavelength selection methodology that allows for a more efficient usage of the currently available multiple wavelength technology. The Wavelength Assignment Algorithm presented in this dissertation helps to reduce the number of wavelengths essential to the realization of high capacity WDM networks. Through an intelligent and straightforward process the Wavelength Assignment Algorithm has been shown to reduce the blocking probability associated with a network's physical topology. By assigning wavelengths based on connection priorities the algorithm has been shown to increase a network's overall data carrying capacity through a reduction in the number of blocked calls encountered. Via computer simulation, the Wavelength Assignment Algorithm exhibits a significant drop in the number of blocked calls experienced with multiple network topologies by allowing wavelengths to be re-used on other non-related connections pairs. Through the re-use of wavelengths, the Wavelength Assignment Algorithm increases the performance potential of WDM networks with a limited number of operational wavelengths available.