Patents by Inventor Jayakrishnan C. Mundarath
Jayakrishnan C. Mundarath 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: 8374650Abstract: A system and method for collaboratively designing optimized beamforming vectors is disclosed for a wireless multiple input, multiple output (MIMO) space division multiple access (SDMA) communication system to optimize an aggregate SNR performance metric across the different users, thereby permitting the flexibility to trade off computational requirements and size of control information exchanged with performance. Using adaptive vector space search methods, the space of all receive beamformers is searched to find the set which maximizes either the sum or product of SNRs of the users.Type: GrantFiled: September 27, 2006Date of Patent: February 12, 2013Assignee: Apple, Inc.Inventors: Jayesh H. Kotecha, Jayakrishnan C. Mundarath
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Publication number: 20130016763Abstract: A wireless communication system noncollaborative, multiple input, multiple output (MIMO) space division multiple access (SDMA) system determines subscriber station combining and weighting vectors that yield a high average signal-to-interference plus noise ratio (SINR). Each subscriber station independently transmits information to a base station that allows the base station to determine a weight vector wi for each subscriber station using the determined combining vector of the subscriber station. The ith combining vector corresponds to a right singular vector corresponding to a maximum singular value of a channel matrix between a base station and the ith subscriber station. Each subscriber station transmits signals using a weight vector vi, which corresponds to a left singular vector corresponding to a maximum singular value of a channel matrix between the ith subscriber station and the base station. The base station uses the weight vector wi to determine the signal transmitted by the ith subscriber station.Type: ApplicationFiled: July 16, 2012Publication date: January 17, 2013Inventors: Jayesh H. Kotecha, Jayakrishnan C. Mundarath
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Publication number: 20120314654Abstract: A multi-user MIMO downlink beamforming system (200) is provided to enable transmit beamforming vectors to be efficiently provided to a subset of user equipment devices (201.i), where spatial separation or zero-forcing transmit beamformers (wi) are computed at the base station (210) and used to generate precoded reference signals (216). The precoded reference signals (216) are fed forward to the user equipment devices (201.i) which apply one or more hypothesis tests (207.i, 208.i) to the precoded reference signals to extract the precoding matrix (W), including the specific transmit beamforming vector (WUE) designed for the user equipment, and this extracted information is used to generate receive beamformers (vi).Type: ApplicationFiled: June 11, 2012Publication date: December 13, 2012Inventors: Jayesh H. Kotecha, Jayakrishnan C. Mundarath
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Patent number: 8271569Abstract: A technique for performing a discrete Fourier transform (DFT) includes storing, in a single-port memory, multiple signal points. A first group of consecutive ones of the multiple signal points are fetched (from a first line of the single-port memory) to a first input register associated with a processor that includes multiple arithmetic units (AUs) that are each configured to perform multiply accumulate (MAC) operations. A second group of consecutive ones of the multiple signal points are then fetched (from a second line of the single-port memory) to a second input register associated with the processor. Selected pairs of the multiple signal points are then loaded (one from each of the first and second input registers for each pair) into the multiple arithmetic units during an initial butterfly stage. Radix-2 butterfly operations are then performed on the selected pairs of the multiple signal points (using the multiple AUs) to provide respective output elements.Type: GrantFiled: June 17, 2008Date of Patent: September 18, 2012Assignee: Freescale Semiconductor, Inc.Inventors: Jayakrishnan C. Mundarath, Leo G. Dehner, Kevin B. Traylor
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Patent number: 8223875Abstract: A wireless communication system noncollaborative, multiple input, multiple output (MIMO) space division multiple access (SDMA) system determines subscriber station combining and weighting vectors that yield a high average signal-to-interference plus noise ratio (SINR). Each subscriber station independently transmits information to a base station that allows the base station to determine a weight vector wi for each subscriber station using the determined combining vector of the subscriber station. The ith combining vector corresponds to a right singular vector corresponding to a maximum singular value of a channel matrix between a base station and the ith subscriber station. Each subscriber station transmits signals using a weight vector vi, which corresponds to a left singular vector corresponding to a maximum singular value of a channel matrix between the ith subscriber station and the base station. The base station uses the weight vector wi to determine the signal transmitted by the ith subscriber station.Type: GrantFiled: April 7, 2009Date of Patent: July 17, 2012Assignee: Apple Inc.Inventors: Jayesh H. Kotecha, Jayakrishnan C. Mundarath
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Patent number: 8199846Abstract: A multi-user multiple-input multiple-output (MU-MIMO) downlink beamforming system (200) is provided to enable transmit beamforming vectors to be efficiently provided to a subset of user equipment devices (201.i), where spatial separation or zero-forcing transmit beamformers (wi) are computed at the base station (210) and used to generate precoded reference signals (216). The precoded reference signals (216) are fed forward to the user equipment devices (201.i) which apply one or more hypothesis tests (207.i, 208.i) to the precoded reference signals to extract the precoding matrix (W), including the specific transmit beamforming vector (WUE) designed for the user equipment, and this extracted information is used to generate receive beamformers (vi).Type: GrantFiled: October 4, 2010Date of Patent: June 12, 2012Assignee: Apple Inc.Inventors: Jayesh H. Kotecha, Jayakrishnan C. Mundarath
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Patent number: 8184750Abstract: A technique for increasing decoding reliability in an adaptive minimum mean squared error with successive interference cancellation (MMSE/SIC) decoder in a channel-coded multiple-input multiple-output (MIMO) communication system. A code block selector evaluates reliability metrics and determines whether the reliability metric of the decoded symbols of a particular indexed code block of a first code word satisfies a quality threshold. Depending upon this determination, a composite second code word is formed at each indexed code block using a previously calculated MMSE-LLR output of a second code word or a SIC-LLR output using the indexed symbols of a first code word. Composite second code word is decoded with increased accuracy.Type: GrantFiled: January 22, 2009Date of Patent: May 22, 2012Assignee: Freescale Semiconductor, Inc.Inventors: Jayakrishnan C. Mundarath, Ning Chen
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Patent number: 8179843Abstract: A channel allocation system for a beam-forming wireless network selects receivers to enroll in communication from a pool of candidate receivers, by off-loading a determination of the effects of adding each candidate receiver to the candidate receiver itself. In one embodiment, the candidate receivers nominate themselves for enrollment based on their determination of aggregate data rate changes resulting from their enrollment and the comparison of this aggregate data rate change against an estimate of the aggregate data rate changes of other candidate receivers.Type: GrantFiled: July 27, 2007Date of Patent: May 15, 2012Assignee: Wisconsin Alumni Research FoundationInventors: Parmeswaran Ramanathan, Jayakrishnan C. Mundarath, Barry Van Veen
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Publication number: 20120114064Abstract: A multi-user MIMO downlink beamforming system with limited feed forward (200) is provided to enable precoding matrix information to be efficiently provided to a subset of user equipment devices (201.i), where zero-forcing transmit beamformers (wi) are computed at the base station (210) and assembled into a precoding matrix (W). The precoding matrix is encoded using a compact reference signal codebook (225, 207.i) for forward link signaling, either by sending bits indicating the index of the transmission matrix used, or by transmitting one or more precoded pilots or reference signals wherein the pilot signals are precoded using vectors uniquely representative of the transmission matrix used which includes candidate reference signal matrices which meet a predetermined condition number requirement, such as a condition number threshold. The precoding matrix information (227) is extracted at the user equipment devices (201.i) using the compact reference signal codebook (207.i) and used by the MMSE receiver (209.Type: ApplicationFiled: May 4, 2011Publication date: May 10, 2012Inventors: Jayesh H. Kotecha, Jayakrishnan C. Mundarath
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Publication number: 20120076032Abstract: A multi-user v downlink beamforming system with limited feedback (200) is provided to enable precoding for multi-stream transmission, where a channel codeword (ui) and one or more channel quality indicator values (CQIA, CQIB) are computed at the user equipment (201.i) on the basis of maximizing a predetermined SINR performance metric (?i) which estimates the receive signal-to-noise-ratio (SINR) at the user equipment (201.i). The computed codeword (ui) and CQI values (or differential values related thereto) are quantized and fed back to help the base station (210) which applies a correction to the appropriate CQI value in the course of designing the transmit beamforming vectors w and determining the appropriate modulation and coding level to be used for downlink data transmission.Type: ApplicationFiled: December 5, 2011Publication date: March 29, 2012Inventors: Jayakrishnan C. Mundarath, Jayesh H. Kotecha
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Publication number: 20120076033Abstract: A system and method for opportunistically designing collaborative beamforming vectors is disclosed for a wireless multiple input, multiple output (MIMO) space division multiple access (SDMA) communication system by sequentially designing beamforming vectors for ranked channels in order to exploit the instantaneous channel conditions to improve per user average SNR performance. Each subscriber station independently transmits information to a base station that allows the base station to determine beamforming vectors for each subscriber station by ranking the subscriber stations by channel strength. Using sequential nullspace methods, the ranked channel matrices are then used to select the channel matrix Hi for the best subscriber station, to design the wi, vi for the best subscriber station as the left and right singular vectors of the MIMO channel matrix Hi, to transform the remaining channels and to continue the process until beamforming vectors are designed for all channels.Type: ApplicationFiled: December 5, 2011Publication date: March 29, 2012Inventors: Jayakrishnan C. Mundarath, Jayesh H. Kotecha
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Patent number: 8073486Abstract: A system and method for opportunistically designing collaborative beamforming vectors is disclosed for a wireless multiple input, multiple output (MIMO) space division multiple access (SDMA) communication system by sequentially designing beamforming vectors for ranked channels in order to exploit the instantaneous channel conditions to improve per user average SNR performance. Each subscriber station independently transmits information to a base station that allows the base station to determine beamforming vectors for each subscriber station by ranking the subscriber stations by channel strength. Using sequential nullspace methods, the ranked channel matrices are then used to select the channel matrix Hi for the best subscriber station, to design the wi, vi for the best subscriber station as the left and right singular vectors of the MIMO channel matrix Hi, to transform the remaining channels and to continue the process until beamforming vectors are designed for all channels.Type: GrantFiled: September 27, 2006Date of Patent: December 6, 2011Assignee: Apple Inc.Inventors: Jayakrishnan C. Mundarath, Jayesh H. Kotecha
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Patent number: 8073069Abstract: A multi-user MIMO downlink beamforming system with limited feedback (200) is provided to enable preceding for multi-stream transmission, where a channel codeword (ui) and one or more channel quality indicator values (CQIA, CQIB) are computed at the user equipment (201.i) on the basis of maximizing a predetermined SINR performance metric (?i) which estimates the receive signal-to-noise-ratio (SINR) at the user equipment (201.i). The computed codeword (ui) and CQI values (or differential values related thereto) are quantized and fed back to help the base station (210) which applies a correction to the appropriate CQI value in the course of designing the transmit beamforming vectors w and determining the appropriate modulation and coding level to be used for downlink data transmission.Type: GrantFiled: January 5, 2007Date of Patent: December 6, 2011Assignee: Apple Inc.Inventors: Jayakrishnan C. Mundarath, Jayesh H. Kotecha
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Patent number: 7961807Abstract: A multi-user multiple input multiple output (MIMO) downlink beamforming system with limited feed forward (200) is provided to enable precoding matrix information to be efficiently provided to a subset of user equipment devices (201.i), where zero-forcing transmit beamformers (wi) are computed at the base station (210) and assembled into a precoding matrix (W). The precoding matrix is encoded using a compact reference signal codebook (225, 207.i) for forward link signaling, either by sending bits indicating the index of the transmission matrix used, or by transmitting one or more precoded pilots or reference signals wherein the pilot signals are precoded using vectors uniquely representative of the transmission matrix used which includes candidate reference signal matrices which meet a predetermined condition number requirement, such as a condition number threshold.Type: GrantFiled: March 16, 2007Date of Patent: June 14, 2011Assignee: Freescale Semiconductor, Inc.Inventors: Jayesh H. Kotecha, Jayakrishnan C. Mundarath
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Publication number: 20110019631Abstract: A multi-user MIMO downlink beamforming system (200) is provided to enable transmit beamforming vectors to be efficiently provided to a subset of user equipment devices (201.i), where spatial separation or zero-forcing transmit beamformers (wi) are computed at the base station (210) and used to generate precoded reference signals (216). The precoded reference signals (216) are fed forward to the user equipment devices (201.i) which apply one or more hypothesis tests (207.i, 208.i) to the precoded reference signals to extract the precoding matrix (W), including the specific transmit beamforming vector (wUE) designed for the user equipment, and this extracted information is used to generate receive beamformers (vi).Type: ApplicationFiled: October 4, 2010Publication date: January 27, 2011Inventors: Jayesh H. Kotecha, Jayakrishnan C. Mundarath
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Patent number: 7809074Abstract: A multi-user multiple input, multiple output (MIMO) downlink beamforming system (200) is provided to enable transmit beamforming vectors to be efficiently provided to a subset of user equipment devices (201.i), where spatial separation or zero-forcing transmit beamformers (wi) are computed at the base station (210) and used to generate precoded reference signals (216). The precoded reference signals (216) are fed forward to the user equipment devices (201.i) which apply one or more hypothesis tests (207.i, 208.i) to the precoded reference signals to extract the precoding matrix (W), including the specific transmit beamforming vector (wUE) designed for the user equipment, and this extracted information is used to generate receive beamformers (vi).Type: GrantFiled: March 16, 2007Date of Patent: October 5, 2010Assignee: Freescale Semiconductor, Inc.Inventors: Jayesh H. Kotecha, Jayakrishnan C. Mundarath
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Publication number: 20100183101Abstract: A technique for increasing decoding reliability in an adaptive minimum mean squared error with successive interference cancellation (MMSE/SIC) decoder in a channel-coded multiple-input multiple-output (MIMO) communication system. A code block selector evaluates reliability metrics and determines whether the reliability metric of the decoded symbols of a particular indexed code block of a first code word satisfies a quality threshold. Depending upon this determination, a composite second code word is formed at each indexed code block using a previously calculated MMSE-LLR output of a second code word or a SIC-LLR output using the indexed symbols of a first code word. Composite second code word is decoded with increased accuracy.Type: ApplicationFiled: January 22, 2009Publication date: July 22, 2010Applicant: Freescale Semiconductor, Inc.Inventors: Jayakrishnan C. Mundarath, Ning Chen
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Publication number: 20100070551Abstract: In a data processing system, having a twiddle factor unit, a method for performing a mixed-radix discrete Fourier transform (DFT) having a block size, N, and a maximum block size, Nmax, wherein the maximum block size includes a radix that is not a power of 2 is provided. The method includes receiving a delta value at an input of the twiddle factor unit, the delta value representing a ratio of a modified maximum bock size to the block size, wherein the modified maximum block size is a power of 2. The method further includes using the delta value to obtain a step size for generating indices of a look-up table stored within the twiddle factor unit, wherein the look-up table stores real and imaginary components of twiddle factors corresponding to a set of block sizes of the DFT.Type: ApplicationFiled: September 17, 2008Publication date: March 18, 2010Inventors: NING CHEN, JAYAKRISHNAN C. MUNDARATH, PORNCHAI PAWAWONGSAK
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Publication number: 20090313314Abstract: A technique for performing a discrete Fourier transform (DFT) includes storing, in a single-port memory, multiple signal points. A first group of consecutive ones of the multiple signal points are fetched (from a first line of the single-port memory) to a first input register associated with a processor that includes multiple arithmetic units (AUs) that are each configured to perform multiply accumulate (MAC) operations. A second group of consecutive ones of the multiple signal points are then fetched (from a second line of the single-port memory) to a second input register associated with the processor. Selected pairs of the multiple signal points are then loaded (one from each of the first and second input registers for each pair) into the multiple arithmetic units during an initial butterfly stage. Radix-2 butterfly operations are then performed on the selected pairs of the multiple signal points (using the multiple AUs) to provide respective output elements.Type: ApplicationFiled: June 17, 2008Publication date: December 17, 2009Inventors: JAYAKRISHNAN C. MUNDARATH, Leo G. Dehner, Kevin B. Traylor
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Patent number: 7602837Abstract: A wireless communication system noncollaborative, multiple input, multiple output (MIMO) space division multiple access (SDMA) system determines subscriber station combining and weighting vectors that yield a high average signal-to-interference plus noise ratio (SINR). Each subscriber station independently transmits information to a base station that allows the base station to determine a weight vector wi for each subscriber station using the determined combining vector of the subscriber station. The ith combining vector corresponds to a right singular vector corresponding to a maximum singular value of a channel matrix between a base station and the ith subscriber station. Each subscriber station transmits signals using a weight vector vi, which corresponds to a left singular vector corresponding to a maximum singular value of a channel matrix between the ith subscriber station and the base station. The base station uses the weight vector wi to determine the signal transmitted by the ith subscriber station.Type: GrantFiled: October 20, 2005Date of Patent: October 13, 2009Assignee: Freescale Semiconductor, Inc.Inventors: Jayesh H. Kotecha, Jayakrishnan C. Mundarath