Tellabs Operations, Inc.

Coriant Operations, Inc.

Richard C Younce

Daniel J Marchok

Kenneth P Laberteaux

Peter J W Melsa

Julia Y Larikova

Charles W K Gritton

Peter J Melsa

Ravi Chandran

Bruce E Dunne

David S Farrell

Kimon Papakos

David W Jenkins

Samir Kapoor

Kenneth M Fisher

Mark E Boduch

Rafid Antoon Sukkar

Charles Wk Gritton

Peng Zhang

Graham Rousell

Mark Patton

Larry Michael Wolfrum

Peter Jw Melsa

A method for routing C-band and L-band optical signals, and a system, apparatus, and computer program that operate in accordance with the method. The method comprises selecting one or more C-band optical signals using one or more C-band components, resulting in one or more selected C-band optical signals. One or more L-band optical signals are selected using one or more L-band components, resulting in one or more selected L-band optical signals. The selected C-band and L-band optical signals are combined.

Reconfigurable optical add/drop multiplexer network element for C-band and L-band optical signals

Current optical networks are engineered to handle amplifier noise and chromatic dispersion. Polarization mode dispersion occurs in optical networks due splitting of the light energy of a pulse propagating in a fiber into two modes. Compensating for polarization mode dispersion is a difficult and expensive task and hence only few commercial systems have been deployed to deal with this issue. A polarization mode dispersion compensation module according to an example embodiment of the present invention compensates for polarization mode dispersion by determining a performance metric related to an error rate of an optical signal in at least one polarization mode in a filtered state. Based on the performance metric, a control vector is determined to control the optical signal in the at least one polarization mode in the filtered state. The control vector is then applied to a polarization effecting device to compensate for polarization mode dispersion.

Method and apparatus for compensating for polarization mode dispersion (PMD)

A reconfigurable optical add drop multiplexer (ROADM) includes local interfaces at which optical signals of different wavelengths are locally input into the ROADM, and a network interface configured to connect the ROADM to a network from which multiplexed optical signals of different wavelengths are transmitted to the network. In a first configuration, the ROADM is configured to transmit from the network interface to the network multiplexed signals of different wavelengths having a first minimum frequency difference. In a second configuration, the ROADM is configured to transmit from the network interface to the network multiplexed signals of different wavelengths having a second minimum frequency difference. The second minimum frequency difference is greater than the first minimum frequency difference. This arrangement reduces the power of four wave mixing cross products produced when optical signals of three wavelengths are multiplexed and transmitted from the ROADM to NZDSF or DSF fiber types.

Reconfigurable optical add/drop multiplexer and procedure for outputting optical signals from such multiplexer

Adaptive Gain Control (AGC) is performed directly in a coded domain. A Coded Domain Adaptive Gain Control (CD-AGC) system modifies at least one parameter of a first encoded signal, resulting in corresponding modified parameter(s). The CD-VQE system replaces the parameter(s) of the first encoded signal with the modified parameter(s), resulting in a second encoded signal. In a decoded state, the second encoded signal approximates a target signal that is a function of two signals, including the first encoded signal and a third encoded signal, in at least a partially decoded states. Thus, the first encoded signal does not have to go through intermediate decode/re-encode processes, which can degrade overall speech quality. Computational resources required for a complete re-encoding are not needed. Overall delay of the system is minimized. The CD-AGC system can be used in any network in which signals are communicated in a coded domain, such as a Third Generation (3G) wireless network.

Method and apparatus for modifying an encoded signal for voice quality enhancement

An embodiment of the invention comprises determining a gain tilt based on power measurements from a power measurement block, determining a noise figure penalty based on the gain tilt, determining a gain tilt compensation to compensate for the gain tilt taking into account the noise figure penalty, and communicating the gain tilt compensation to an amplifier block to apply the gain tilt compensation to subsequently received wavelengths.

Method and apparatus for gain tilt compensation over fiber optic cable

A method of managing a signal over a symbol period includes supplying samples of the signal at beginning and end portions of the symbol period. The method further includes suppressing the supply of samples of the signal at a middle portion of the symbol period.

OFDM/DMT/ digital communications system including partial sequence symbol processing

Increasing data rates in next-generation optical networks requires a change in the type of optical modulation used to encode optical signals carried by the optical networks. Different types of optical modulation incur different optical impairments, which may degrade the fidelity of the optical signals by reducing the optical signal-to-noise ratio (OSNR). A method or corresponding apparatus in an example embodiment of the present invention provides a planning tool for deploying an optical network in a manner based on the optical modulation that reduces the cost and complexity of the deployed network. In one embodiment, the disclosed planning tool may adjust a model of the optical network to be deployed by changing the topology and/or the number and/or type of optical network elements in response to optical impairments for a given optical modulation.

OSNR model for optical engineering rules used in a planning tool

High optical communication rates are making their way into networks initially designed for 10 Gigabits per seconds (Gbps). These higher rates of 40 Gbps and higher have shorter signaling periods and are more susceptible to differential group delay (DGD). A method and corresponding apparatus in an example embodiment of the present invention compensates for polarization state sensitivity of a receiver by determining a performance metric relating to an error rate due to transmission and reception of a modulated optical signal in a medium introducing DGD. Based on the performance metric, a control vector is determined to control a polarization state of the modulated optical signal. The control vector is applied to a polarization effecting device to compensate for the DGD and the polarization state sensitivity of the receiver. Communication rates of 40 Gbps and higher can be used in transmission mediums that introduce DGD through use of embodiments presented.

Method and apparatus for polarization stabilization in optical receivers with complex modulation formats

OFDM/DMT/digital communications system including partial sequence symbol processing

A method of providing dispersion compensation includes providing a dispersion signal indicative of an amount of dispersion for at least one channel of a multi-channel optical signal. A dispersion compensator is controlled in accordance with the dispersion signal to optically compensate for the dispersion of the optical signal.

Optical dispersion compensation

An echo canceller circuit is set forth. The echo canceller circuit includes a digital filter having adaptive tap coefficients to simulate an echo response occurring during a call. The adaptive tap coefficients are updated during the call using a Means Squares process. A tap energy detector is also employed. The tap energy detector identifies and divides groups of taps having high energy from groups of taps having low energy. The high energy tap groups are smaller in number than the low energy tap groups. The high energy tap groups are adapted separately from the low energy tap groups using the Least Squares process. Still further, the high energy tap groups may be adapted using an adaptive gain constant &#x3b1; while the low energy tap groups are adapted using an adaptive gain constant &#x3b1;', wherein &#x3b1;&#x3e;&#x3b1;&#x2032;.

Echo canceller employing dual-H architecture having split adaptive gain settings

Methods and apparatus for processing a received voice signal from a variable-delay network by a communications system that has at least one echo canceller. An echo canceller determines delay characteristics that are associated with the received voice signal and correspondingly modifies echo cancellation processing. In a variation of the embodiment of the invention, a first echo canceller sends silence descriptor information to a second echo canceller. The second echo canceller reconstructs a voice signal based upon the silence descriptor information and excitation vector information.

Synchronization of echo cancellers in a voice processing system

An echo canceller circuit for use in an echo canceller system is set forth that provides sensitive double-talk detection. The echo canceller circuit comprises a second digital filter having adaptive tap coefficients to simulate an echo response occurring during the call. The adaptive tap coefficients of the second digital filter are updated over the duration of the call using a Least Mean Squares process having an adaptive gain a. A channel condition detector is used to detect channel conditions during the call. The channel condition detector is responsive to detected channel conditions for changing the adaptive gain a during the call. For example, the channel condition detector may detect the presence of a double-talk condition and set the adaptive gain a to zero. Similarly, the channel condition detector may detect the occurrence of a high background noise condition and set the adaptive gain a to a level less than 1 that is dependent on the detected level of the background noise. Other similar channel conditions and corresponding adaptive gain settings may likewise be utilized.

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Wakarush, IN, United States of America

Richard C Younce