Limited Wavelength Conversion in All-Optical Tree Networks
نویسنده
چکیده
Let T be a symmetric directed tree, i.e., a tree with each edge viewed as two opposite directed links. We consider the problem of routing arbitrary sets of connection requests in T. In all-optical communication tree networks with WDM (wavelength-division multiplexing) this is equivalent to color (assign wavelengths to) a given set of directed paths so that no two directed paths of the same color use the same link of T. Let W be the number of available wavelengths. The load, that is, the maximum number of directed paths passing through a link of T cannot exceed W. If there is no wavelength conversion available then each request (directed path) is restricted to a single wavelength and it is known that the minimum number of colors needed to color any set of directed paths in a tree is lower bounded away from the load L of the paths on the tree; moreover, no algorithm is known that uses a number of colors less than 5L=3. The presence of wavelength converters allows to overcome this limits. The complexity of converters is measured by its maximum degree, which represents the maximum number of possible conversions of any given wavelength. We show that it is possible to route any set of requests of load L W (1 ?), where depends only on the degree of the converters. Moreover, we show that in any tree it is possible to route any set of requests of load L W if converters of degree O(p W) are used. In case of trees containing at most one node of degree 4 we show that converters of degree 3 already allow to greedly route any set of requests of load L W ; moreovere, there exists explicitely constructable converters of degree 9 already allow to greedly route any set of requests of load L W .
منابع مشابه
Multiwavelength Optical Networks With Limited Wavelength Conversion - INFOCOM '97. Sixteenth Annual Joint Conference of the IEEE Computer and Communications Societies.
This paper proposes optical wavelength division multiplexed (WDM) networks with limited wavelength conversion that can eficiently support lightpaths (connections) between nodes. Each lightpath follows a route in the network and must be assigned a channel along each link in its route. The load A , , , of a set of lightpath requests is the maximum over al l links of the number of lightpaths that ...
متن کاملRouting in all-optical DWDM networks with sparse wavelength conversion capabilities
This work focuses on the Routing and Wavelength Assignment (RWA) problem in all-optical DWDM networks with Sparse Wavelength Conversion (SWC) capabilities. By sparse wavelength conversion, we mean that nodes within the optical network domain might or might not support optical wavelength conversion. For these nodes that support optical wavelength conversion, the number of wavelength converters m...
متن کاملUtilization of Optical Fibre WDM Channel in Wavelength Routed Networks using Sparse Partial Limited Wavelength Conversion
In the previous 20 years, wavelength conversion has received a considerable attention due to its strong influence on the blocking performance of wavelength-routed WDM networks. In a wavelength-routed WDM network, end users communicate with one another via all-optical WDM channels. In all-optical WDM channels optical fibre is used. Optical fibre is a single, hair-fine filament drawn from molten ...
متن کاملA Novel Protection Guaranteed, Quality of Transmission Aware Routing and Wavelength Assignment Algorithm for All-optical Networks
Transparent All Optical Networks carry huge traffic and any link failure can cause the loss of gigabits of data; hence protection and its guarantee becomes necessary at the time of failure. Many protection schemes were presented in the literature, but none of them speaks about protection guarantee. Also, in all optical networks, due to absence of regeneration capabilities, the physical layer i...
متن کاملComputing Approximate Blocking Probabilities in Wavelength Routed All-Optical Networks with Limited- - INFOCOM '99. Eighteenth Annual Joint Conference of the IEEE Computer and Communications Societies
Absfrcrcf-In this paper, we propose a method to calculate the average blocking probability in all-optical networks using limited-rmge wavelength conversion. Previous works have shown that there is a remarkable improvement in blocking probability while using limited-range wavelength conversion [2], [3] but these analytical models were either for a path [2] or for a mesh-torus network [3]. Using ...
متن کامل