Patents Represented by Attorney, Agent or Law Firm Aprilia U. Diaconescu
  • Patent number: 6347000
    Abstract: A communications network has a plurality of nodes interconnected by an optical transmission medium. The transmission medium is capable of a carrying a plurality of wavelengths organized into bands. A filter at each node for drops a band associated therewith and passively forwards other bands through the transmission medium. A device is provided at each node for adding a band to the transmission medium. Communication can be established directly between a pair of nodes in the network sharing a common band without the active intervention of any intervening node. This allows the network to be protocol independent. Also, the low losses incurred by the passive filters permit relatively long path lengths without optical amplification.
    Type: Grant
    Filed: August 12, 1999
    Date of Patent: February 12, 2002
    Assignee: Nortel Networks Limited
    Inventors: David Milton, Tomas Valis, Gino Totti, Kexing Liu, Michel Pigeon
  • Patent number: 6298038
    Abstract: A configuration for a transport node of a telecommunication system comprises a pair of transparent mux/demuxs provided at two sites and connected over a high rate span. The T-Muxs provide continuity of all tribs and maintain a lower bit rate linear or ring system through the higher bit rate span. The lower bit rate linear or ring system operates as if it were directly connected without the higher bit rate midsection. For the forward direction of the traffic, the T-Mux comprises a multi-channel receiver for receiving a the trib signals and providing for each trib signal a trib data signal and a trib OAM&P signal. The data signals are multiplexed into a supercarrier data signal and the OAM&P signals are processed to generate a supercarrier OAM&P signal. A supercarrier transmitter maps the supercarrier data signal and the supercarrier OAM&P signal into a supercarrier signal and transmits same over the high rate span. Reverse operations are effected for the reverse direction of traffic.
    Type: Grant
    Filed: April 24, 1997
    Date of Patent: October 2, 2001
    Assignee: Nortel Networks Limited
    Inventors: David Wright Martin, Mohammed Ismael Tatar, Alan Glen Solheim, Timothy James Armstrong, Mark Stephen Wight, Ronald J. Gagnon, David John Nicholson
  • Patent number: 6246668
    Abstract: A method and apparatus for hitless path switching whereby synchronous traffic is re-directed from an alternate path back over a primary path. A trace message is inserted at an originating path terminal into an information signal and the information signal is transmitted along the primary path and the alternate path. The information signal experiences different delays along the primary and alternate paths. The receiving path terminal is provided with two pointer processors, one for the primary path and one for the alternate path. The pointer processors use a first and a second buffer, respectively, for storing a number of frames of the respective information signal. The information signals arrive at the selector phase aligned, after the pointer processors perform positive and negative stuffing, respectively.
    Type: Grant
    Filed: June 9, 1998
    Date of Patent: June 12, 2001
    Assignee: Nortel Networks Limited
    Inventor: Richard Glenn Kusyk
  • Patent number: 6239889
    Abstract: The power of an optical signal (s1) travelling on a channel (&lgr;1) of a WDM transmission system, is measured using a signature bit pattern (sBP1) which is inserted in the frame of the optical signal (s1). The power level of sBPL is adjusted at the launching point to a predetermined ratio (m) with the power of the optical signal. At a point of interest, the fiber is tapped and a fraction of the tapped signal, that includes a corresponding fraction of sBP1, is converted to an electrical signal. The fraction of sBP1 is extracted from a the electrical signal and power of sBPL is measured. This gives the optical power of s1 as (m) is known and also the calibration constant for the respective channel (&lgr;1) is known. The method can be applied for any and all channels of the WDM transmission system.
    Type: Grant
    Filed: December 5, 1997
    Date of Patent: May 29, 2001
    Assignee: Nortel Networks Limited
    Inventors: James Harley, Richard A. Habel
  • Patent number: 6236499
    Abstract: A modular bidirectional optical amplification system includes a multiwavelength dual amplifier building block, a multiwavelength unidirectional booster amplifier BB, a unidirectional and a bidirectional Optical Service Channel (OSC) BB, an Intelligent Optical Terminal Accessway (IOTA) module, and an interleaved filter BB. The dual amplifier BB is available in a C-band version, an E-band version and a hybrid version, and provides unidirectional or bidirectional multichannel amplification. The booster amplifier is available in a C-band version, an E-band version and in a booster plus variant;. one for the C-band and one for E-band. The unidirectional and bidirectional OSC BBs provide a means for OAM&P functionality to the optical network. The IOTA BB provides multiplexing and demultiplexing, and the filter BB provides separation of the signal into grid-1 and grid-2 channels.
    Type: Grant
    Filed: April 15, 1999
    Date of Patent: May 22, 2001
    Assignee: Nortel Networks Limited
    Inventors: Loren S. Berg, Mark R. Hinds, Robert W. Keys, Gregory D. May, Alan G. Solheim, Stephane St-Laurent
  • Patent number: 6222668
    Abstract: A fast means of detecting that a fiber has been disconnected at one end of a bidirectional optical amplifier by monitoring for several signature effects simultaneously. Upon detection of a loss of signal, the pump laser in the corresponding direction is shut off quickly to prevent oscillation from occurring should the other end of the amplifier be subsequently disconnected.
    Type: Grant
    Filed: May 8, 1998
    Date of Patent: April 24, 2001
    Assignee: Nortel Networks Limited
    Inventors: Mathieu Dutrisac, Richard Achile Habel, Robert Keys, Franz Li Hsien Mok, Jeffrey Alan Weslowski
  • Patent number: 6219162
    Abstract: A method of equalizing the channels of a WDM link comprises identifying an error threshold level BERFail for the BER defined for each signal S(j) in accordance with the channel rate, and determining the attenuation A(j) of, for example, the power P(j) of each signal S(j) transmitted over the WDM link. The transmitter powers are adjusted taking into account the attenuations determined for all channels. The attenuation A(j) for channel (j) is determined by first setting the power P(j) of all signals S(j) to a maximum PMax, attenuating the power P(j) of channel (j) until the BER reaches the threshold value BERFail, measuring the power corresponding to the BERFail for that channel, and calculating the difference between the PMax and P(j)Fail. The transmitter powers are then set according to the relationship P(j)=PMax−&eegr;(A(j)−AMin), where &eegr; is 0.8 for a system with 3-4 channels.
    Type: Grant
    Filed: April 27, 2000
    Date of Patent: April 17, 2001
    Assignee: Nortel Networks Limited
    Inventors: Chris Wilhelm Barnard, Chung Yu Wu
  • Patent number: 6161136
    Abstract: The user interface is divided into client-server portions, based on the multilevel model-view-controller (MMVC) architecture. The MMVC architecture results in a high performance user interface that addresses the problem of how to divide functionality, and introduces performance issues in a distributed or three-tier architecture. This division of concerns results in a dramatic reduction in the size of the component which runs on the user's terminal, resulting in lighter weight client interfaces, that are flexible and powerful and does not require to have a high bandwidth connection to the server. Thus, the user's terminal may be a low-end personal computer with a dial-up access to the Internet service provider. This layered structure may be built over an existing network manager provided with a graphical user interface.
    Type: Grant
    Filed: October 16, 1998
    Date of Patent: December 12, 2000
    Assignee: Nortel Networks Limited
    Inventors: Arn Close Hyndman, Omar G. Ocampo
  • Patent number: 6115157
    Abstract: A method of equalizing the channels of a WDM link comprises identifying an error threshold level BER.sub.Fail for the BER defined for each signal S(j) in accordance with the channel rate, and determining the attenuation A(j) of, for example, the power P(j) of each signal S(j) transmitted over the WDM link. The transmitter powers are adjusted taking into account the attenuations determined for all channels. The attenuation A(j) for channel (j) is determined by first setting the power P(j) of all signals S(j) to a maximum P.sub.Max, attenuating the power P(j) of channel (j) until the BER reaches the threshold value BER.sub.Fail, measuring the power corresponding to the BER.sub.Fail for that channel, and calculating the difference between the P.sub.Max and P(j).sub.Fail. The transmitter powers are then set according to the relationship P(j)=P.sub.Max -.eta.(A(j)-A.sub.Min), where .eta. is 0.8 for a system with 3-4 channels.
    Type: Grant
    Filed: December 24, 1997
    Date of Patent: September 5, 2000
    Assignee: Nortel Networks Corporation
    Inventors: Chris Wilhelm Barnard, Chung Yu Wu
  • Patent number: 6111676
    Abstract: In WDM systems, each wavelength travels over a different optical paths, thus having different reflections within the path. This method for detecting reflections in bidirectional multichannel communication systems uses a unique signature attached to each signal. This allows to isolate reflections within each optical path, by measuring the optical power of a signal and of the reflection, by measuring the power of the signal and the power of the reflection. The location of the reflection is determined by calculating the relative delay between the signal and the respective reflection.
    Type: Grant
    Filed: February 26, 1998
    Date of Patent: August 29, 2000
    Assignee: Nortel Networks Corporation
    Inventors: Avid Lemus, James Harley, Marc Veilleux
  • Patent number: 6084694
    Abstract: A communications network has a plurality of nodes interconnected by an optical transmission medium. The transmission medium is capable of a carrying a plurality of wavelengths organized into bands. A filter at each node for drops a band associated therewith and passively forwards other bands through the transmission medium. A device is provided at each node for adding a band to the transmission medium. Communication can be established directly between a pair of nodes in the network sharing a common band without the active intervention of any intervening node. This allows the network to be protocol independent. Also, the low losses incurred by the passive filters permit relatively long path lengths without optical amplification.
    Type: Grant
    Filed: August 12, 1999
    Date of Patent: July 4, 2000
    Assignee: Nortel Networks Corporation
    Inventors: David Milton, Tomas Valis, Gino Totti, Kexing Liu, Michel Pigeon
  • Patent number: 6075985
    Abstract: A fixed wireless access system includes a base station for bidirectional communication with a switching center, a private branch exchange (PBX) for bidirectional communication with a plurality of user stations, and a wireless trunk interface (WTI). The WTI communicates with the base station over a bidirectional wireless air link, and with the PBX over a bidirectional trunk line. Since a wireless link is established between a dual radio unit (DRU) at the base station and a transceiver at the WTI, the slots normally allocated to the directory number of the called and calling parties in the current air interface, must be used to identify the transceiver involved in the exchange of information. Therefore, the DN of the called station behind the PBX is transmitted to the WTI using other fields of the air interface, and presented to PBX in a format acceptable for establishing a correct connection (DID service).
    Type: Grant
    Filed: January 23, 1997
    Date of Patent: June 13, 2000
    Assignee: Nortel Networks Corporation
    Inventor: Joel Kao
  • Patent number: 6069718
    Abstract: The BER is used as a parameter for evaluating the performance of an optical transmission system. Performance of optical systems is also defined by the Q factor, which uniquely determines the BER in the absence of distortion. The measurements are effected in a point of operation of the channel which gives a value of interest for the Q factor. To this end, the optical SNR is lowered by adding noise over the information signal. A distortion-free Q (Q.sub.DF) and a back-to-back Q (Q.sub.BB) are determined in the same operating point of the system. The distortion penalty for transmitter-receiver pair may be determined by comparing Q.sub.DF to Q.sub.BB. The noise loading technique will allow to investigate if equalizing. The value of OSNRs at the output of a particular system results in equalizing the noise margin in that systems or not.
    Type: Grant
    Filed: September 19, 1997
    Date of Patent: May 30, 2000
    Assignee: Nortel Networks Corporation
    Inventor: Farideh Khaleghi
  • Patent number: 6009383
    Abstract: A voice service node (VSN) serving a wireless speech terminal (WST) connected to a mobile switching center (MSC) comprises a bypass unit, a speech codec and a speech recognizer. The bypass unit exchanges messages with a remote bypass unit at the MSC, and switches the operation of the VSN between a PCM mode, for analog speech terminals, and a codec bypass mode, for digital speech terminals. The speech codec operates during the bypass mode to decode a speech frame into a sequence of digital words for the speech recognizer and to encode a voice prompt signal form a speech prompting system from a sequence of digital words into a speech frame. The speech recognizer receives the sequence of digital words and a flag indicating the status of the frame and provides a set of parameters characterizing the sequence of digital words. The set of parameters and the flag are applied to a distance computation unit for determining a set of distances between a speech model and the set of parameters.
    Type: Grant
    Filed: October 30, 1997
    Date of Patent: December 28, 1999
    Assignee: Nortel Networks Corporation
    Inventor: Georges Mony
  • Patent number: 6008916
    Abstract: The BER is used as a parameter for evaluating the performance of an optical transmission system. Performance of optical systems is also defined by the Q factor, which indicates the signal-to-noise ratio of the electric signal regenerated by the receiver. In the absence of distortion, Q is univocally determined by the BER. Q is calculated using an estimated BER measured with the path under normal conditions of operation, and a distortion-free Q is determined in the same operating point of the system. The distortion penalty for the path is obtained by comparing the measured Q with the distortion free Q. In addition, the distortion penalty for a transmitter-receiver pair, and a distortion penalty for a transmission link between the transmitter and receiver may be determined.
    Type: Grant
    Filed: September 19, 1997
    Date of Patent: December 28, 1999
    Assignee: Nortel Networks Corporation
    Inventor: Farideh Khaleghi
  • Patent number: 5945860
    Abstract: A CML/ECL clock phase shifter device provides a 360.degree. phase control range and, upon being provided with two CML clock signals related by a known phase difference, the device produces any desired phase in response to a control signal. The device uses a CMOS current switch which generates current signals having the amplitude adjustable with the control signal, which is a digital word. Differential pairs provide amplitude modulated current signals for the input clock and the variant of the input clock. Two MOS transmission networks selectively invert each amplitude modulated signal and sum the signals from each side on a load network. The phase control resolution is optimal over four quadrants for quadrature input clock signals.
    Type: Grant
    Filed: January 4, 1996
    Date of Patent: August 31, 1999
    Assignee: Northern Telecom Limited
    Inventors: Bernard Guay, Michael Altmann
  • Patent number: 5946313
    Abstract: The invention provides for a E-Mux and a method for encapsulating/segmenting ATM cells into/from an Ethernet frame at the boundary between an ATM and an Ethernet network. An Ethernet end-station on the E-Mux is addressed using multiple MAC level identifiers, which are dynamically assigned according to the ATM virtual circuits which terminate on that end station, and have only transitory significance on the Ethernet. A unique ATM OUI identifies the frames carrying ATM-traffic.
    Type: Grant
    Filed: March 20, 1997
    Date of Patent: August 31, 1999
    Assignee: Northern Telecom Limited
    Inventors: David Ian Allan, Liam M. Casey, Andre J. Robert
  • Patent number: 5910753
    Abstract: A universal synchronizer for use in a variety of telecommunications systems based on direct digital phase synthesis (DDPS) include digital and analog PLLs. The synchronizer may be used for wireless, optical, or wireline transmission systems and for a wide ranges of data rates. Digital phase detectors are used in the digital PLLs for comparing the phase of the local clock f.sub.L with the phase of a respective digital reference clock, and provides a respective phase error signal. A digital phase synthesis unit receives the phase error signal and a target phase error and produces a first and a second set of control signals for driving an error driver. The error driver generates the control voltage for adjusting the frequency of a VCXO that is used for all PLLs, to lock the respective PLL. The first set of control signal generates the control voltage for the digital PLLs, and the second set of control signals generates the control voltage for the analog PLLs and for the acquisition mode of operation of all PLLs.
    Type: Grant
    Filed: September 19, 1997
    Date of Patent: June 8, 1999
    Assignee: Northern Telecom Limited
    Inventor: Wladyslaw Bogdan
  • Patent number: 5859716
    Abstract: In an apparatus and method for troubleshooting a transmission system comprising optical line amplifiers (OA), optical reflections can be detected irrespective if a data signal is present or absent. Each OA is equipped with a self-stimulation signal detection unit for generating a low frequency local code unique to the transmission system and dithering the outgoing signal in a controlled manner with the local code. Each OA attempts to detect its local code in the incoming signal by comparing the energy of the transmitted and received dithers. The presence of the local code in the incoming signal initiates alarms which unequivocally identify the faulted OA. Each OA selects its local code out of a bank of local codes, according to a priority scheme and re-selects its local code in case of conflicts.
    Type: Grant
    Filed: January 18, 1996
    Date of Patent: January 12, 1999
    Assignee: Northern Telecom Limited
    Inventors: Maurice Stephen O'Sullivan, Kim Byron Roberts, James St.Leger Harley, Jeffrey Alan Weslowski
  • Patent number: 5841760
    Abstract: A configuration for a SONET transport node comprises a pair of transparent mux/demuxs provided at two sites and connected over a high rate span. The T-Muxs provide continuity of all tribs and maintain a lower bit rate linear or ring system through the higher bit rate span. The lower bit rate linear or ring system operates as if it were directly connected without the higher bit rate midsection. For the forward direction of the traffic, the T-Mux comprises a multi-channel receiver for receiving the trib signals and providing for each trib signal a trib SPE and a trib OH. The trib SPEs are multiplexed into a supercarrier SPE and the trib OHs signals are processed to generate a supercarrier OH. A supercarrier transmitter maps the supercarrier SPE and the supercarrier OH into a supercarrier signal and transmits same over the high rate span. Reverse operations are effected for the reverse direction of traffic.
    Type: Grant
    Filed: April 24, 1997
    Date of Patent: November 24, 1998
    Assignee: Northern Telecom Limited
    Inventors: David Wright Martin, Mohammed Ismael Tatar, Alan Glen Solheim, Timothy James Armstrong, Mark Stephen Wight, Ronald J. Gagnon, David John Nicholson