Architectures for WDM Benes Interconnection Network with Simultaneous Space-Wavelength Switching Capability
ABSTRACT In this paper, we present three switch architectures for WDM (Wavelength Division Multiplexing) Benes network that are based on wavelength exchange optical crossbar (WOC). A WOC is capable of performing a single-step space-switching wavelength-conversion between two wavelengths. A WOC can be implemented by the simultaneous power exchange between two optical signals. Unlike existing designs, the proposed architectures do not require separate stages of wavelength converters. This leads to a switch design that has a smaller total number of components as well as a smaller number of components in the signal path. Moreover, wavelength conversion is performed between two predefined and fixed wavelengths. This avoids the need for expensive full-range wavelength converters used in most of the existing designs. Systematic methods to realize switch architectures with an arbitrary number of wavelengths and fibers are given. The three architectures are evaluated and compared to existing architectures on the basis of hardware cost.
Conference Paper: Design of Wavelength Cross-Connects Based on Permutations among Fibers[Show abstract] [Hide abstract]
ABSTRACT: A wavelength cross-connect (WXC) is an optical cross-connect with external stage of wavelength converters. It is a crucial element in a wavelength division multiplexing (WDM) network. A new type of WXC, namely wavelength-exchanging cross-connect (WEX), was recently proposed. Because WEX can simultaneously perform switching and wavelength converting, it has low hardware complexity. To achieve switching nonblocking, the designs of current WXCs (including WEXs) are based on full-permutation switching, which provides any permutation of input signals at the output of the cross-connect. This may result in routing of various wavelengths originating from a fiber to a particular fiber; and they may also perform wavelength converting. Such permutations may not be necessary in a WDM network. We propose a novel concept to design WEXs, which is based on the permutations among output fibers, but not among output ports. This leads to the reduction of the number of permutations, as well as the complexity of WEXs. In designing such WEXs, we propose the following method: (i) using a permutation matrix to describe the operation of a 2×2 element in a WEX; and (ii) applying a permutation matrix product rule to simplify the architecture of the WEX.Photonics and Optoelectronics (SOPO), 2012 Symposium on; 01/2012
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ABSTRACT: Planar permutation networks are a class of multistage switching networks with no crossover between paths that interconnect switching elements. A well-known class of planar networks is the N−Stage network that provides a good compromise between the crossbar and the Benes network. In this paper, we address the problem of designing cost-effective N-Stage optical planar networks with space-wavelength switching capability. Such networks are used for switching in communication and computing systems that employ Wavelength Division Multiplexing (WDM) technology. We investigate two classes of space-wavelength N-stage planar networks, and for each class, we design a number of switching networks and analyze their hardware complexity. In addition, we propose a new method for designing a class of space-wavelength planar networks with reduced complexity. It is shown that, for F ≤ W (where F is the total number of fibers and W that of wavelengths) the proposed method results in planar networks with an average of 67% reduction in overall cost compared to that of networks based on fixed-range wavelength converters.Photonic Network Communication 05/2007; 13(3):297-312. DOI:10.1007/s11107-006-0045-y · 0.75 Impact Factor
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ABSTRACT: In wavelength division multiplexing (WDM) networks, wavelength cross-connect (WXC) is an important device which consists of space switching elements (SSEs) and wavelength converters (WCs) to provide the switching functionality of connection between its inputs and outputs. Wavelength-exchange optical crossbar (WOC) is a novel photonic switching element which enables performing space switching and wavelength converting in a single-step. By replacing some conventional 2�?2 space switching elements with WOCs, a new class of photonic switch architectures called wavelength-exchanging cross connect (WEX) has been proposed to eliminate all WCs used in all of the existing WXC designs. In order to achieve nonblocking connection, the photonic switch architectures are designed to provide connections of full-permutation, which indicate that the outputs are all possible permutations of the inputs. We observe that some permutations, such as to mutually exchange the wavelengths within the same fiber, are equivalent and hence may not be necessary. Since the number of connection permutations of a photonic switch is proportional to its hardware complexity, the switch architecture with only sufficient permutations consequently has low complexity. We propose a design methodology to construct such new WDM photonic switches based on Benes WEX type with 2 fibers, by eliminating some switching elements whose control states are always in bar or cross for sufficient permutations. Our study results show that (i) in cases of Benes WEX switch with 2 wavelengths in each fiber, 2 out of 6 switching elements can be eliminated; (ii) in cases of Benes WEX switch with 4 wavelengths in each fiber, 4 out of 18 switching elements can be eliminated.