Optical: systems and elements – Deflection using a moving element – Using a periodically moving element
Reexamination Certificate
1999-06-23
2001-05-22
Pascal, Leslie (Department: 2633)
Optical: systems and elements
Deflection using a moving element
Using a periodically moving element
Reexamination Certificate
active
06236478
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates, generally, to a method for monitoring optical communication equipment and, more specifically, to a monitoring method wherein both the levels of the total signals on a plurality of optical fibers are checked and the signal qualities of individual communication channels respectively transmitted on one fiber are monitored in order to establish a monitoring algorithm by which critical channels are monitored more intensively than reliable ones.
2. Description of the Prior Art
Monitoring problems in an optical transport network are described, for example, in “IEEE Journal on Selected Areas in Communications”, Vol. 14, No. 5, June 1996, pp. 914-922. At present, optical communication systems (All Optical Networks/Photonic Transport Networks) are in the standardization phase. This entails an orientation to the existing standards for synchronous communication systems (SDH-Synchronous Digital Hierarchy; SONET—Synchronous Optical Network) in the defining of the characteristic structural features; the aim being a maximum structural similarity of the network structures. In purely optical add/drop multiplexers or cross-connectors, which may be employed medium-term, there are approximately 30 to 300 optical channels to be wired to one another. As is already the case in known synchronous communication systems, rather high requirements are placed upon the operating reliability in the purely optical systems. However, these can be guaranteed only if the optical channels are continuously individually monitored with respect to their signal quality and if substitute transmission paths are immediately available in case of error.
The time-span between the arising of an error and the completion of the substitution process is 50 ms in synchronous networks. In order to be able to integrate the new purely optical communication systems into the overall communication network without complications, these reaction times must be maintained or even shortened. However, a monitoring of all the optical communication channels using conventional transmission equipment is associated with prohibitive technical outlay and, thus, with prohibitive costs.
It is therefore an object of the present invention to offer a method for monitoring optical communication systems having a plurality of optical channels, wherein the method can be realized cost-effectively.
SUMMARY OF THE INVENTION
What distinguishes the monitoring system of the present invention is that, unlike conventional methods, the total signals (wavelength division multiplex signals) which are respectively transmitted on one fiber and their individual optical communication channels are monitored separately. Also unlike conventional methods, priorities are set particularly in the monitoring of the individual optical channels. As such, endangered connections and critical communication channels are monitored more intensively than others.
The priorities are determined with the aid of an evaluation system which functions on the basis of algorithms of neural networks; i.e., the basis of fuzzy logic as well as rule-based algorithms (expert systems). This evaluation system delivers an observation sequence which allows the recognition of errors within the prescribed reaction time with the greatest possible probability at given the lowest possible outlay. The main advantage resides in the reduction of the wiring outlay for the monitoring equipment.
Another advantage of the present invention is the learning behavior, so that the option exists of further improving the reliability of the error detection during the operation without having to change the hardware. The ability to easily differentiate the signal quality allows the advantageous application of fuzzy logic.
In an embodiment, a method is provided for monitoring optical signals on a plurality of optical fibers wherein the method includes the steps of: simultaneously detecting a total level for each of the plurality of optical fibers; deriving a total value criterion from the total level; evaluating the total value criterion; monitoring communication channels of the plurality of optical fibers in a cyclical manner; deriving channel quality criteria from the monitoring; evaluating the channel quality criteria; and controlling a monitoring algorithm for the plurality of optical fibers based on the evaluation of both the total value criterion and the channel quality criteria wherein critical communication channels are monitored more intensively.
In an embodiment of the method, the total levels are evaluated according to fuzzy logic criteria.
In an embodiment, a method for monitoring optical signals is provided which further includes the step of evaluating changes of the total level on the plurality of optical fibers.
In an embodiment, a method for monitoring optical signals is provided which further includes the step of evaluating qualities of the individual communication channels.
In an embodiment of the method, the evaluation of both the total value criterion and the channel quality criteria occurs via learning algorithms.
In an embodiment of the method, the evaluation of both the total value criterion and the channel quality criteria occurs via rule-based algorithms.
In an embodiment, a method for monitoring optical signals is provided which further includes the steps of determining additional information about errors in the optical fibers and the communication channels; and using the additional information in controlling the monitoring algorithm.
In an embodiment, a method for monitoring optical signals is provided which further includes the steps of determining an error situation based on monitoring results; and prompting equivalent circuits by at least one of channel, fiber and assembly.
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: 4449247 (1984-05-01), Waschka, Jr.
patent: 5329392 (1994-07-01), Cohen
patent: 5532864 (1996-07-01), Alexander et al.
patent: 5859302 (1998-12-01), Strasser et al.
patent: 6064501 (2000-05-01), Roberts et al.
Bell Boyd & Lloyd LLC
Lieu Vu
Pascal Leslie
Siemens Aktiengesellschaft
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