Management, Monitoring and Performance Optimization of Optical Networks
First Claim
1. An optical subchannel muxponder that can transmit optical signals among a plurality of nodes interconnected by one or more fiber optic cables to form an optical network, the optical subchannel muxponder comprising:
- (a) a subchannel mapper that can map each of a plurality of client signals to any available subchannel of any ITU channel, wherein each ITU channel has a predefined ITU frequency and a corresponding plurality of subchannels, and wherein each subchannel has an associated frequency with a predetermined offset from the predefined ITU frequency of the subchannel'"'"'s corresponding ITU channel;
(b) one or more lasers that can be tuned to generate modulated client signals at frequencies associated with each subchannel; and
(c) a multiplexer that can combine the modulated client signals for transmission onto the fiber optic cables of the optical network.
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Accused Products
Abstract
The present invention includes novel techniques, apparatus, and systems for optical WDM communications. Tunable lasers are employed to generate respective subcarrier frequencies which represent subchannels of an ITU channel to which client signals can be mapped. In one embodiment, subchannels are polarization interleaved to reduce crosstalk. In another embodiment, polarization multiplexing is used to increase the spectral density. Client circuits can be divided and combined with one another before being mapped, independent of one another, to individual subchannels within and across ITU channels. A crosspoint switch can be used to control the client to subchannel mapping, thereby enabling subchannel protection switching and hitless wavelength switching. Network architectures and subchannel transponders, muxponders and crossponders are disclosed, and techniques are employed (at the subchannel level/layer), to facilitate the desired optical routing, switching, concatenation and protection of the client circuits mapped to these subchannels across the nodes of a WDM network.
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Citations
41 Claims
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1. An optical subchannel muxponder that can transmit optical signals among a plurality of nodes interconnected by one or more fiber optic cables to form an optical network, the optical subchannel muxponder comprising:
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(a) a subchannel mapper that can map each of a plurality of client signals to any available subchannel of any ITU channel, wherein each ITU channel has a predefined ITU frequency and a corresponding plurality of subchannels, and wherein each subchannel has an associated frequency with a predetermined offset from the predefined ITU frequency of the subchannel'"'"'s corresponding ITU channel; (b) one or more lasers that can be tuned to generate modulated client signals at frequencies associated with each subchannel; and (c) a multiplexer that can combine the modulated client signals for transmission onto the fiber optic cables of the optical network. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14)
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15. A system for multiplexing, transmitting and demultiplexing polarization-multiplexed signals, the system comprising:
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(a) a polarization combiner that combines a first set of signals aligned along a first linear polarization axis with a second set of signals aligned along a second linear polarization axis, wherein the first and second polarization axes are orthogonally polarized; (b) a transmitting medium which can modify polarization states of the first and second sets of signals, but will maintain orthogonality of the polarization between the sets of signals; (c) a polarization tracker that receives a plurality of transmitted signals from the first and second sets of signals, and modifies the polarization states of the received signals to transform the polarization state of the first set of signals to a first output linear polarization axis, and correspondingly transform the polarization state of the second set of signals to a second output linear polarization axis that is orthogonal to the first output linear polarization axis; (d) a polarization beam splitter at the output of the polarization tracker with one of its output linear polarization axes aligned with the first output polarization axis of the polarization tracker, and the other output polarization axis aligned with the second output polarization axis of the polarization tracker; (e) feedback circuitry that monitors and analyzes one or both outputs of the polarization beam splitter, and provides a control signal back to the polarization tracker to align the signal polarizations of the first set of signals with the first polarization axis of the polarization beam splitter, and to align the signal polarizations of the second set of signals with the second polarization axis of the polarization beam splitter; and (f) at least one optical filter at the output of each branch of the polarization beam splitter that demultiplexes the signals in each linear polarization. - View Dependent Claims (16, 17, 18, 19, 20)
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21. A method for transmitting optical signals among a plurality of nodes interconnected by one or more fiber optic cables to form an optical network, the method comprising the following steps:
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(a) mapping each of a plurality of client signals to any available subchannel of any ITU channel, wherein each ITU channel has a predefined ITU frequency and a corresponding plurality of subchannels, and wherein each subchannel has an associated frequency with a predetermined offset from the predefined ITU frequency of the subchannel'"'"'s corresponding ITU channel; (b) tuning one or more lasers to generate modulated client signals at frequencies associated with each subchannel; and (c) combining the modulated client signals for transmission onto the fiber optic cables of the optical network. - View Dependent Claims (22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34)
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35. A method for multiplexing, transmitting and demultiplexing polarization-multiplexed signals, the method comprising the following steps:
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(a) combining a first set of signals aligned along a first liner polarization axis with a second set of signals aligned along a second linear polarization axis, wherein the first and second polarization axes are orthogonally polarized; (b) launching the combined signals onto a transmitting medium which can modify polarization states of the first and second set of signals, but will maintain orthogonality of the polarization between the sets of signals; (c) receiving a plurality of transmitted signals from the first and second sets of signals, and modifying the polarization states of the received signals to transform the polarization state of the first set of signals to a first output linear polarization axis, and correspondingly transform the polarization state of the second set of signals to a second output linear polarization axis that is orthogonal to the first output linear polarization axis; (d) splitting the first set of signals aligned with the first output polarization axis from the second set of signals aligned with the second output polarization axis; (e) monitoring and analyzing one or both of the split sets of signals, and generating a control signal to align the signal polarizations of the first set of signals with the first output linear polarization axis, and to align the signal polarizations of the second set of signals with the second polarization axis; and (f) demultiplexing the signals in each linear polarization. - View Dependent Claims (36, 37, 38, 39, 40)
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41. An improved method for upgrading optical network equipment that can transmit and receive optical signals among a plurality of nodes interconnected by one or more fiber optic cables to form an optical network, the method comprising the following steps:
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(a) deploying a first, second and third legacy transceiver at respective first, second and third network nodes, each legacy transceiver capable of transmitting and receiving a first client signal at a first legacy data rate via a first ITU channel; and (b) upgrading each of the first and second legacy transceivers by adding the capabilities of; (i) mapping each of a plurality of second client signals to any available subchannel of any ITU channel, wherein each ITU channel has a predefined ITU frequency and a corresponding plurality of subchannels, and wherein each subchannel has an associated frequency with a predetermined offset from the predefined ITU frequency of the subchannel'"'"'s corresponding ITU channel, and (ii) transmitting and receiving each of the plurality of second client signals, each at the first legacy data rate, via the plurality of subchannels to which the plurality of second client signals have been mapped, thereby effectively increasing the bandwidth of each of the first and second legacy transceivers; (c) whereby the overall effective bandwidth of the system has been increased with minimal or no disruption to the operation of non-upgraded legacy equipment, in that; (i) the first and second upgraded legacy transceivers can transmit and receive the plurality of second client signals between the first and second nodes at a bandwidth greater than the first legacy data rate, and (ii) the third legacy transceiver can transmit and receive the first client signal at the first legacy data rate between the third node and either the first or second nodes.
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Specification