Optical 2-fiber ring network

Details Optical 2-fiber ring network Optical 2-fiber ring network

1999-06-29

2001-06-05

Ngo, Hung N. (Department: 2874)

Optical waveguides

With optical coupler

Plural

C385S032000

Reexamination Certificate

active

06243512

ABSTRACT:

BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an optical 2-fiber ring network for wave-division multiplex systems with several add-drop-multiplexer-terminals.
2. Description of the Prior Art
Optical networks are frequently conceived as ring networks in order to have an alternate path available when malfunctions of the regular transmission path occur. The article Multiwavelength Survivable Ring Network Architectures, A. F. Elrefaie, Bellcore, Red Bank, N.J. 07701, USA, 0-7803-0950-2/93/$3.001993IEEE, pages 1245 through 1251 discloses such ring architectures for a wavelength-division multiplex system.
The ring networks are frequently provided with what is referred to as add-drop multiplexers that serve the purpose of branching and inserting transmission channels. Previously, these functions were performed by electrical signals. In the future, optically working switching matrixes, however, are supposed to take over these functions. These optically working switching matrixes are inserted into ring structures, are realized with small outlay and exhibit protection circuits (alternate circuits).
SUMMARY OF THE INVENTION
A particular advantage of the ring network of the present invention is that a specific wavelength is allocated to each line assembly (allocated to a participant) not only for the outgoing signals but also for the received signals. This wavelength is retained for the transmission not only in the working channels of the ring network but also in the protection channels. The switching between non-malfunctioning and protection mode occurs via simple optical circuit means.
Accordingly, in an embodiment of the present invention, a 2-fiber ring network is provided which has a plurality of terminals for branching and inserting a plurality of data channels, wherein the 2-fiber rings are formed as first and second optical fiber rings and have opposite unidirectional transmission paths, and which further includes: a first transmission band wherein a first group of data channels from the plurality of data channels is allocated to the first transmission band and transmitted in the first optical fiber ring, each of the data channels in the first group having a same wavelength; a second transmission band wherein a second group of data channels from the plurality of data channels is allocated to the second transmission band and transmitted in the second optical fiber ring, each of the data channels in the second group having a same wavelength; and a plurality of optical switches wherein, upon a transmission path malfunction in one of the two optical fiber rings, working data channels from the malfunctioning optical fiber ring are inserted, via the optical switches and the plurality of terminals, as protection channels into the other optical fiber ring and retain their respective wavelengths.
In an embodiment, given a transmission path malfunction in both of the optical fiber rings between certain of the plurality of terminals, the working data channels are redirected via other terminals to the other optical fiber ring.
In an embodiment, each optical fiber ring has a separate switching matrix.
In an embodiment, the network further includes a plurality of line multiplexers for combining the working channels and the protection channels to form multiplex signals to be emitted; and a plurality of line demultiplexers for receiving the multiplexing signals and for separating the working channels and the protection channels.
In an embodiment, the network further includes a plurality of wavelength demultiplexers for outputting data channels to the switching matrix, the plurality of wavelength demultiplexers having inputs connected to outputs of the plurality of line multiplexers via the optical switches; and a plurality of wavelength multiplexers provided with data channels from the switching matrix, the plurality of wavelength multiplexers having outputs connected to inputs of the plurality of line multiplexers via the optical switches.
Additional features and advantages of the present invention are described in, and will be apparent from, the Detailed Description of the Preferred Embodiments and the Drawing.


REFERENCES:
patent: 5701372 (1997-12-01), Magel et al.
patent: 6052495 (2000-04-01), Little et al.
patent: 6108465 (2000-08-01), Iida et al.
patent: 0 651 529 A1 (1993-10-01), None
patent: 0 651 528 A1 (1993-10-01), None
patent: 0 716 521 A2 (1995-12-01), None
Abstract, EP 651528, Oct. 29, 1993, Huber et al.
Abstract, EP 651529, Oct. 29, 1993, Huber et al.
Multiwavelength Survivable Ring Network Architectures, A.F. Elrefaie, pp. 1245-1251; 1993; IEEE.
First Results of an experimental Coloured Section Ring, Hamel et al., pp. 3.51-3.54; 22ndEuropean Conference on Optical Communication, 1996.

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