Nortel Networks Corporation

Northern Telecom Limited

Other

Ciena Corporation

Rockstar Consortium US LP

Frederic J Simard

Philip K Edholm

David Robert Cuddy

Osama S Aboul-Magd

Ornan A Gerstel

Rajiv R Ramaswami

Andre John Van Schyndel

Michael Brown

Laura A Mahan

Robert William Keys

Edgar Velez

Robert R Ward

Nina K Burns

Michael C G Lee

Kevin Stuart Farley

Humair Raza

Christopher Michael Forrester

Vasant Sahay

Babu O Narayanan

Hugh M Collins

Anant Grewal

David Park

Saeid Seydnejad

Xiaoqing Hu

Emmanuel Seitelbach

David W Park

Kun Han

Aiping Liang

Zhongwei Li

Automatic discovery and verification of optical communication links as well as isolation of link failures in an optical communication system.

Link discovery, verification, and failure isolation in an optical communication system

The present invention employs in-band signaling between PTEs to provision and control session keys, which are used by the PTEs for encrypting and decrypting traffic that is carried from one PTE to another over a transport network. In operation, a first PTE will receive incoming traffic from a first edge network, map the traffic to frames, encrypt the traffic with a session key, and send the frames with the encrypted traffic over the transport network to a second PTE. The second PTE will extract the encrypted traffic from the frames, decrypt the encrypted traffic with a session key, and send the recovered traffic over a second edge network toward an intended destination. If symmetric encryption is employed, the session key used by the first PTE to encrypt the traffic will be identical to the session key used by the second PTE to decrypt the traffic.

Controlling session keys through in-band signaling

The performance of a voice conference using a packet-based conference bridge can be improved with a number of modifications. In one modification, the conference bridge receives speech indication signals from the individual packet-based terminals within the voice conference, these speech indication signals then being used by the conference bridge to select the talkers within the voice conference. This removes the need for speech detection techniques within the conference bridge, hence decreasing the required processing power and the latency within the conference bridge. In another modification, the conference bridge sends addressing control signals to the individual packet-based terminals selected as talkers, these addressing control signals directing the terminals selected as talkers to directly transmit their voice data packets to the other terminals within the voice conference. This direct transmission of voice data packets can reduce transcoding and latency within the network. These two modifications could further be combined, resulting in a conference bridge that receives speech indication signals, selects the talkers for the voice conference and outputs addressing control signal to the talkers. In this case, the advantages of the two modifications are gained as well as additional capacity advantages resulting from no voice signals actually traversing the conference bridge.

Apparatus and method for packet-based media communications

The present invention relates to a variable clamp equalization method and apparatus, the method includes measuring optical signal to noise ratio (OSNR) values for each wavelength, computing a raw power adjustment value for each wavelength, computing a raw power adjustment correction factor for each computed raw power adjustment value based on a computed OSNR range value in accordance with a pre-defined variable clamp value schedule, wherein a larger clamp is scheduled for use when the computed OSNR range value is larger, and a smaller clamp is scheduled for use when the computed OSNR range value is smaller. The method further includes determining a clamped power adjustment value for each wavelength, applying the corresponding determined clamped power adjustment value to each wavelength, and iterating the aforementioned until the computed OSNR range value is within pre-defined boundaries, whereby the signal is considered equalized.

Variable clamp equalization method and apparatus

Packet-based central conference bridges, packet-based network interfaces and packet-based terminals are used for voice communications over a packet-based network. Modifications to these apparatuses can reduce the latency and the signal processing requirements while increasing the signal quality within a voice conference as well as point-to-point communications. For instance, by selecting the talkers prior to the decompression of the voice signals, decreases in the latency and increases in signal quality within the voice conference can result due to a possible removal of the decompression and subsequent compression operations in a conference bridge unnecessary in some circumstances. Further, the removal of the jitter buffers within the conference bridges and the moving of the mixing operation to the individual terminals and/or network interfaces are modifications that can cause lower latency and transcoding within the voice conference.

A performance monitoring method for an optically amplified transmission system. The method provides the optical power at each amplifier site, taking into account the inaccuracies introduced by the SRS in the power estimation obtained with the current methods. An optical spectrum analyzer is used at the output of the transmission link of interest to accurately measure the output power of each wavelength. This value is sent upstream to the last amplifier in the link, to compute an error term as the difference between the actual measurement and the estimation. The error term is used to infer the SRS-induced error by system elements not accounted for in the model. The error term is then fed-back to each amplifier in the link, so that the estimated power is adjusted to account for the SRS-induced inaccuracy.

Optical performance monitoring for D/WDM networks

The invention provides a method and apparatus for establishing a non-obtrusive data channel within a voice communication channel to transmit data during an audio transmission without disruption. This audio transmission can be for example, an audio conversation between a first and a second party. The invention uses spread spectrum modulation to hide the reception and transmission of data from the first and second party and allow the ongoing conversation to proceed uninterrupted. In a preferred embodiment, the invention is used to provide an enhanced call waiting feature whereby caller identifying (ID) information of a third party is transmitted over a telephone line from a local central office (CO) to a first party engaged in a telephone conversation with a second party. Advantageously, the use of spread spectrum modulation to transmit data in a voice channel carrying a telephone conversation prevents any interruption in the on-going conversation and does not result in any noticeable disruption.

Method and apparatus for delivering non-obtrusive data services by spread spectrum modulation

In method of controlling an optical amplifier dynamically adapts to both configuration and performance changes of a communications system. An error vector is calculated to indicate a difference between respective detected values and target values of a parameter of a light beam downstream of the optical amplifier. A sensitivity matrix indicative of a sensitivity of the detected parameter value to incremental changes in a control variable of the optical amplifier is calculated. A predicted optimum value of the control variable is then calculated using the error vector and the sensitivity matrix. Calculation of the predicted optimum control variable value can be iterative, with the sensitivity matrix calculated either during each iteration, or at the beginning of each optimization run. As a result, optimization of the amplifier control variables is performed based on a sensitivity matrix that accurately reflects the performance of the amplifier.

Adaptive optical amplifier control

Portable wireless telephone handset with a flap movable upon a housing. In a first position the flap is close to a speaker to enable the flap to be disposed near to a user's ear for the user to receive personal low volume sound from the speaker. In a second position, the flap is further from the speaker to detract from use of the speaker near to the user's ear. In the second position of the flap, the speaker operates in loudspeaker mode. A switch is provided to change the speaker between loudspeaker and low volume sound mode, the switch operation being dependent upon flap position.

Wireless telephone handset

A digital FSK demodulator includes a quadrature phase detector for detecting space and mark tones used in FSK signals. Due to its inherent characteristics, a telephone loop in which the demodulator is used produces unequal amplitudes in detected mark and space tones. The inequality or offset must be cancelled so that a proper timing signal can be recovered from the FSK signal. The demodulator includes a digital compensation circuit for off-hook and on-hook offset cancellation.

Digital FSK demodulator with offset cancellation

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Hull, Canada

Frederic J Simard