Patents by Inventor Chandra Bontu
Chandra Bontu has filed for patents to protect the following inventions. This listing includes patent applications that are pending as well as patents that have already been granted by the United States Patent and Trademark Office (USPTO).
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Patent number: 8977277Abstract: A method at a network node for obtaining spectrum sensing information, the method communicating to at least one of a user equipment and a sensing node at least one event condition for spectrum sensing; providing to the at least one of the user equipment and the sensing node channel descriptors for reporting; and receiving a report from the at least one of the user equipment and the sensing node utilizing the channel descriptors, the report indicating the at least one event condition has been met.Type: GrantFiled: August 30, 2012Date of Patent: March 10, 2015Assignee: BlackBerry LimitedInventors: Sophie Vrzic, Chandra Bontu, Shalini Suresh Periyalwar, David G. Steer
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Publication number: 20130142100Abstract: A method at a user equipment and the user equipment, the method: obtaining an event having event conditions from system information multicasts of a plurality of network nodes; and sending an uplink message to at least one network node for any event whose conditions are satisfied utilizing resources allocated for the event. Also, a method at a network node and the network node, the method multicasting an event having event conditions to a plurality of user equipments; receiving a communication from a user equipment attached to the said network node or any neighbor network nodes, said communication providing an indication that the event conditions are met at the user equipment; compiling statistics, based on the receiving, of network conditions; and performing resource allocation based on the compiled statistics.Type: ApplicationFiled: June 8, 2012Publication date: June 6, 2013Applicant: RESEARCH IN MOTION LIMITEDInventors: Sophie Vrzic, Chandra Bontu, David G. Steer
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Patent number: 8300591Abstract: To allocate resources in an orthogonal frequency domain multiple access (OFDMA) system, two-dimensional rectangular regions are assigned in a frequency-time space to data bursts associated with mobile stations. At least one data burst does not fit in an available space in the frequency-time space is determined. In response to the determining, the assigned two-dimensional rectangular regions are reshaped.Type: GrantFiled: December 7, 2007Date of Patent: October 30, 2012Assignee: Apple Inc.Inventors: Chandra Bontu, Parsya Larijani, Mark Hawryluck
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Publication number: 20110261786Abstract: A base station communicates, with a mobile station, data associated with a packet-switched session in which the mobile station is involved. In response to a handover request from the mobile station, the base station accesses information provisioned for the mobile station to determine whether the mobile station is to be subjected to mobility restriction. Based on the accessed information, the base station determines whether to allow handover of the mobile station. A message is sent to the mobile station to indicate that the requested handover is not allowed if the base station determines that the requested handover is not allowed.Type: ApplicationFiled: April 22, 2009Publication date: October 27, 2011Inventors: Chandra Bontu, Surya Tenneti, Devaki Chandramouli, David Anderson
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Patent number: 7899340Abstract: Methods and systems for compensating a frequency mismatch ?f between a local Oscillator (LO) of a coherent optical receiver and a carrier of a received optical signal. An average frequency of the LO is controlled to compensate at least long-period variations of the frequency mismatch. An electrical carrier recovery circuit for compensating short period variations of the frequency mismatch.Type: GrantFiled: April 7, 2006Date of Patent: March 1, 2011Assignee: Ciena CorporationInventors: Chandra Bontu, Han Sun, Kim B Roberts, Kuang Tsan Wu
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Patent number: 7894728Abstract: A method of compensating phase error between parallel digital signals of a received optical signal, in a coherent optical receiver. A phase differential between the digital signals is determined. A digital skew is imposed between the digital signals, an amount of skew imposed being an integer number of sample periods calculated to most nearly compensate the phase differential. The skewed digital signals are then digitally processed, in the frequency domain, to compensate a residual portion of the phase differential.Type: GrantFiled: October 17, 2006Date of Patent: February 22, 2011Assignee: Ciena CorporationInventors: Han Sun, Chandra Bontu, Kim B. Roberts, John Sitch, John Wolczanski
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Patent number: 7894724Abstract: A method and system for averaging the effects of polarization distortions across a multitude of transmitted data streams in a dual polarization multiplexed optical communications system. Data streams are interleaved amongst each other in accordance with a predetermined pattern. The interleaved data streams are symbol mapped and modulated to provide a pair of optical signals. The pair of optical signals are orthogonally polarized, and multiplexed for transmission across an optical fiber. A receiver circuit receives the transmitted signal and extracts the interleaved data streams. The interleaved data streams are de-interleaved to generate the original data streams. While the data streams can be interleaved and transmitted via a single wavelength optical signal, the data streams can be interleaved and transmitted over two or more different wavelength optical signals to further mitigate the effects of polarization distortions.Type: GrantFiled: March 31, 2005Date of Patent: February 22, 2011Assignee: Ciena CorporationInventors: Chandra Bontu, Leo Strawczynski
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Patent number: 7769305Abstract: In a coherent optical receiver, a frequency domain engine digitally processes at least two multi-bit sample streams of a received optical signal. The frequency domain engine includes a Fast Fourier Transform (FFT) filter for computing a complex vector representative of a frequency-domain spectrum of the received optical signal. A transpose and add block computes a vector sum of the complex vector and a transposed version of the complex vector, and an Inverse Fast Fourier Transform (IFFT) filter computes a complex output vector from the addition result. With this arrangement, parallel real filter operations are efficiently performed on each of the multi-bit sample streams, using a single back-to-back FFT-IFFT filter structure.Type: GrantFiled: September 21, 2006Date of Patent: August 3, 2010Assignee: Nortel Networks LimitedInventors: Kim B. Roberts, Han Sun, Chandra Bontu, Kuang Tsan Wu
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Patent number: 7684712Abstract: A method of recovering a most likely value of each symbol transmitted through an optical communications network using a high speed optical signal. A stream of multi-bit digital samples of the optical signal is processed to generate a respective multi-bit estimate X?(n) of each transmitted symbol. A first function is applied to each symbol estimate X?(n) to generate a corresponding soft decision value {tilde over (X)}(n). Each soft decision value {tilde over (X)}(n) is processed to generate a corresponding hard decision value. {circumflex over (X)}(n) having an ideal amplitude and phase. A plurality of successive soft decision values and hard decision values are processed to determine a second function, which is applied to each soft decision value {tilde over (X)}(n) to generate a most likely symbol value {circumflex over ({circumflex over (X)}(n).Type: GrantFiled: October 20, 2006Date of Patent: March 23, 2010Assignee: Nortel Networks LimitedInventors: Kim B. Roberts, Chandra Bontu, Kuang Tsan Wu, Han Sun
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Patent number: 7636525Abstract: A method and system for initializing a coherent optical receiver. Upon detection of an optical signal, a multi-bit digital sample stream of the optical signal is digitally processed to initialize each one of a plurality of adaptive control blocks of the coherent optical receiver. The adaptive control blocks include at least a dispersion compensation block and a clock recovery block. The dispersion compensation block is initialized before initializing the clock recovery block.Type: GrantFiled: June 13, 2006Date of Patent: December 22, 2009Assignee: Nortel Networks LimitedInventors: Chandra Bontu, Kim B. Roberts, Han Sun, Edgar Velez, Kuang Tsan Wu
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Patent number: 7627252Abstract: A method of recovering a clock signal from an optical signal received through an optical communications system. A digital sample stream is processed to generate a dispersion compensated signal. The dispersion compensated signal is then tapped to obtain upper side band and lower side band signals of each received polarization of the optical signal. The upper side band and lower side band signals are then processed to compensate polarization dependent impairments, and the clock recovered from the resulting optimized.Type: GrantFiled: December 23, 2005Date of Patent: December 1, 2009Assignee: Nortel Networks LimitedInventors: Han Sun, Slobodan Jovanovic, Kuang Tsan Wu, Chandra Bontu, Kim B Roberts, Jianzhong Xu
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Patent number: 7599400Abstract: A method of minimizing jitter in a system for rate adapting a data signal for transport through a synchronous network. A phase difference is measured between a data clock synchronous with the data signal and a local clock of the synchronous network. A timing reference (F) indicative of a frequency difference between the asynchronous data signal and the local clock is measured using the measured phase difference. Calculation of the timing reference includes compensating ambiguity in the measured phase difference.Type: GrantFiled: September 6, 2005Date of Patent: October 6, 2009Assignee: Nortel Networks LimitedInventors: Kim B. Roberts, Chandra Bontu, James Harley
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Patent number: 7555227Abstract: A method of processing a stream of digital samples of an optical signal received by a coherent optical receiver. The digital sample stream is processed to generate a dispersion compensated sample stream. The dispersion compensated sample stream is then processed to compensate polarization dependent impairments of the optical signal.Type: GrantFiled: December 6, 2005Date of Patent: June 30, 2009Assignee: Nortel Networks LimitedInventors: Chandra Bontu, Maurice O'Sullivan, Kim B. Roberts, Han Sun, Kuang Tsan Wu
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Patent number: 7532822Abstract: A method of recovering a clock signal from an optical signal received through an optical communications system. A digital sample stream is processed to generate a dispersion compensated signal. The dispersion compensated signal is then tapped to obtain upper side band and lower side band signals of each received polarization of the optical signal. The upper side band sand lower side band signals are then processed to compensate polarization dependent impairments and the clock recovered from the resulting optimized.Type: GrantFiled: December 23, 2005Date of Patent: May 12, 2009Assignee: Nortel Networks LimitedInventors: Han Sun, Slobodan Jovanovic, Kuang Tsan Wu, Chandra Bontu, Kim B Roberts, Jianzhong Xu
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Patent number: 7522841Abstract: A method of a conveying data through an optical communications system. An optical signal is received through the optical communication system, the optical signal comprising data symbols and SYNC bursts, each SYNC burst having a predetermined symbol sequence. The received optical signal is oversampled to generate a multi-bit sample stream. The sample stream is partitioned into blocks of contiguous samples, wherein each block of samples partially overlaps at least one other block of samples and encompasses at least one SYNC burst and a plurality of data symbols. Each block of samples is independently processed to detect a value of each data symbol.Type: GrantFiled: January 10, 2006Date of Patent: April 21, 2009Assignee: Nortel Networks LimitedInventors: Chandra Bontu, Kuang Tsan Wu, John McNicol, Kim B. Roberts, Han Sun
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Patent number: 7418212Abstract: A system and method for detecting digital symbols carried in a received optical signal. The system comprises a functional element operative to receive a stream of samples of an electrical signal derived from the received optical signal and to evaluate a non-linear function of each received sample, thereby to produce a stream of processed samples. The system also comprises a detector operative to render decisions about individual symbols present in the received optical signal on the basis of the stream of processed samples. In an embodiment, the non-linear function computes substantially the square root of each received sample.Type: GrantFiled: October 1, 2003Date of Patent: August 26, 2008Assignee: Nortel Networks LimitedInventor: Chandra Bontu
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Publication number: 20070092260Abstract: A method of a conveying data through an optical communications system. An optical signal is received through the optical communication system, the optical signal comprising data symbols and SYNC bursts, each SYNC burst having a predetermined symbol sequence. The received optical signal is oversampled to generate a multi-bit sample stream. The sample stream is partitioned into blocks of contiguous samples, wherein each block of samples partially overlaps at least one other block of samples and encompasses at least one SYNC burst and a plurality of data symbols. Each block of samples is independently processed to detect a value of each data symbol.Type: ApplicationFiled: January 10, 2006Publication date: April 26, 2007Applicant: Nortel Networks LimitedInventors: Chandra Bontu, Kuang Wu, John McNicol, Kim Roberts, Han Sun
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Publication number: 20070092259Abstract: A method of processing a stream of digital samples of an optical signal received by a coherent optical receiver. The digital sample stream is processed to generate a dispersion compensated sample stream. The dispersion compensated sample stream is then processed to compensate polarization dependent impairments of the optical signal.Type: ApplicationFiled: December 6, 2005Publication date: April 26, 2007Applicant: Nortel Networks LimitedInventors: Chandra Bontu, Maurice O'Sullivan, Kim Roberts, Han Sun, Kuang Wu
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Publication number: 20070053384Abstract: A method of minimizing jitter in a system for rate adapting a data signal for transport through a synchronous network. A phase difference is measured between a data clock synchronous with the data signal and a local clock of the synchronous network. A timing reference (F) indicative of a frequency difference between the asynchronous data signal and the local clock is measured using the measured phase difference. Calculation of the timing reference includes compensating ambiguity in the measured phase difference.Type: ApplicationFiled: September 6, 2005Publication date: March 8, 2007Applicant: Nortel Networks LimitedInventors: Kim Roberts, Chandra Bontu, James Harley
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Publication number: 20060285855Abstract: A method of recovering a clock signal from an optical signal received through an optical communications system. A digital sample stream is processed to generate a dispersion compensated signal. The dispersion compensated signal is then tapped to obtain upper side band and lower side, band signals of each received polarization of the optical signal. The upper side band sand lower side band signals are then processed to compensate polarization dependent impairments and the clock recovered from the resulting optimized.Type: ApplicationFiled: December 23, 2005Publication date: December 21, 2006Applicant: Nortel Networks LimitedInventors: Han Sun, Slobodan Jovanovic, Kuang Wu, Chandra Bontu, Kim Roberts, Jianzhong Xu