Patents by Inventor Narayan Prasad

Narayan Prasad 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).

  • Feed-forward control signaling and decoding schemes
    Patent number: 8599951
    Abstract: Systems and methods for conveying wireless transmission allocation information are disclosed. In accordance with one method, an index indicating selected data stream parameters is received. In addition, an indication of a number of transmit antennas at a transmitter from which the data stream is transmitted is also received. Further, the selected parameters are determined from the index based on the number of transmit antennas at the transmitter. Moreover, data signals are received and processed with a processor in accordance with the selected data stream parameters.
    Type: Grant
    Filed: May 25, 2011
    Date of Patent: December 3, 2013
    Assignee: NEC Laboratories America, Inc.
    Inventors: Mohammad A. Khojastepour, Narayan Prasad, Sampath Rangarajan
  • Receiver with prefiltering for discrete fourier transform-spread-orthogonal frequency division multiplexing (DFT-S-OFDM) based systems
    Patent number: 8576959
    Abstract: A receiver for discrete Fourier transform-spread-orthogonal frequency division multiplexing (DFT-S-OFDM) based systems, including a prefilter for received signal codeword(s); and a log-likelihood ratio LLR module responsive to the prefilter; wherein the prefilter includes a pairing and whitening module that based on channel estimates and data rate enables the LLR module to perform either a Serial-In-Serial-Out (SISO) based log likelihood ratio processing of an output from the paring and whitening module or a two-symbol max-log soft output demodulator (MLSD) based log likelihood ratio processing of an output from the pairing and whitening module.
    Type: Grant
    Filed: April 16, 2009
    Date of Patent: November 5, 2013
    Assignee: NEC Laboratories America, Inc.
    Inventors: Narayan Prasad, Xiaodong Wang, Shuangquan Wang
  • SIGNALING OF MIXTURE COMBINATION SETS
    Publication number: 20130286971
    Abstract: A method implemented in a user terminal used in a wireless communications system is disclosed. The method comprises receiving an index, referencing a table of indices in which the received index denotes at least a total number of co-scheduled streams and one or more modulation schemes, determining at least one modulation scheme of at least one co-scheduled user based on the referencing, and receiving data signals and processing the data signals by utilizing the at least one modulation scheme, wherein each index of a plurality of the indices in the table denotes a total number of co-scheduled streams and denotes one or more stream indices for a user terminal to which the index is directed. Other methods, systems, and apparatuses also are disclosed.
    Type: Application
    Filed: June 22, 2013
    Publication date: October 31, 2013
    Inventors: MOHAMMAD A. KHOJASTEPOUR, NARAYAN PRASAD, SAMPATH RANGARAJAN
  • User Pairing and Resource Allocation for Downlink Multiuser Multi-Input-Multi-Output In Long Term Evolution Advanced Systems
    Publication number: 20130250868
    Abstract: A method for user pairing and resource allocation, includes performing a multiuser multi-input-multi-output (MU-MIMO) user pairing process to maximize an objective metric without common rank restriction; performing a rank balancing process to determine a uniform transmission user rank along all allocated resource blocks for each user; and with the uniform transmission user rank fixed for all the users, determining optimal user pairing and allocation for each of the resource blocks for each user.
    Type: Application
    Filed: September 18, 2012
    Publication date: September 26, 2013
    Applicant: NEC LABORATORIES AMERICA, INC.
    Inventors: Guosen Yue, Narayan Prasad, Sampath Rangarajan
  • METHODS AND SYSTEMS FOR CONVEYING SCHEDULING INFORMATION OF OVERLAPPING CO-SCHEDULED USERS IN AN OFDMA-MU-MIMO SYSTEM
    Publication number: 20130242926
    Abstract: A method implemented in a base station for conveying scheduling information in an orthogonal frequency division multiple access (OFDMA) multi-user (MU)-multiple input multiple output (MIMO) system is disclosed. The method includes transmitting to a first user equipment (UE) the scheduling information including first scheduling information of the first UE and at least a portion of second scheduling information of at least one second UE, wherein the scheduling information includes a resource block (RB) assigned to the first UE, the number of streams, and an indication of one or more dedicated reference symbol (RS) layers assigned to the first UE. Other methods, systems, and apparatuses also are disclosed.
    Type: Application
    Filed: May 7, 2013
    Publication date: September 19, 2013
    Applicant: NEC Laboratories America, Inc.
    Inventors: Narayan Prasad, Mohammad Ali Khojastepour, Meilong Jiang, Xiaodong Wang, Sampath Rangarajan
  • Method and systems for conveying scheduling information of overlapping co-scheduled users in an OFDMA-MU-MIMO system
    Patent number: 8532051
    Abstract: Methods and systems for conveying or transmitting to any given user in an OFDMA-MU-MIMO system scheduling information of other co-scheduled users to permit the user to perform error-correction on received data and/or interference reduction on its received signals. The scheduling information can include resource block assignment, modulation constellations employed, coding rates employed, power levels utilized and precoder matrix indices used. Further, the scheduling information can be conveyed in part through dedicated reference symbol layers or pilot streams. Moreover, a base station may transmit a preliminary estimate of the total number of users the base station expects to schedule, or an upper-bound on the total number of users, to the MU-MIMO users to permit the MU-MIMO users to determine preferred precoder matrix indices and indications of channel quality indices.
    Type: Grant
    Filed: November 15, 2011
    Date of Patent: September 10, 2013
    Assignee: NEC Laboratories America, Inc.
    Inventors: Narayan Prasad, Mohammad Ali Khojastepour, Meilong Jiang, Xiaodong Wang, Sampath Rangarajan
  • BEAMFORMING
    Publication number: 20130231058
    Abstract: A method implemented in a wireless communications system is disclosed. The method includes determining a first candidate set of transmit beams for a wireless transmitter having a transmit antenna array and a second candidate set of receive beams for a wireless receiver having a receive antenna array, transmitting, from the wireless transmitter, each transmit beam in the first candidate set, and applying, at the wireless receiver, receive beams in the second candidate set to receive said each transmit beam in the first candidate set. Other methods, systems, and apparatuses also are disclosed.
    Type: Application
    Filed: April 17, 2013
    Publication date: September 5, 2013
    Applicant: NEC Laboratories America, Inc.
    Inventors: Kishore Ramachandran, Narayan Prasad, SAMPATH RANGARAJAN
  • Coordinated Multiple Point Transmission and Reception
    Publication number: 20130229992
    Abstract: A method implemented in a mobile communications network supporting coordinated multiple point transmission and reception (CoMP) is disclosed. The method includes transmitting, to a user equipment (UE), data in a physical downlink shared channel (PDSCH), and transmitting a reference signal to the UE, wherein a union of resource elements (REs) allocated for reference signals transmitted from a subset of a plurality of transmission points (TPs) in a CoMP set are excluded from resource mapping for transmitting the data to the UE. Other methods, systems, and apparatuses also are disclosed.
    Type: Application
    Filed: January 25, 2013
    Publication date: September 5, 2013
    Applicant: NEC LABORATORIES AMERICA, INC.
    Inventors: Guosen Yue, Narayan Prasad, Meilong Jiang, Sampath Rangarajan
  • BEAMFORMING
    Publication number: 20130231059
    Abstract: A method implemented in a wireless communications system is disclosed. The method includes: transmitting, from a wireless transmitter having a transmit antenna array, a first signal on each of a plurality of different transmit beams in transmitter (TX) sector level sweep (SLS), receiving, at a wireless receiver having a receive antenna array, the first signal, and determining, at the wireless receiver, quality of the first signal. Other methods, systems, and apparatuses also are disclosed.
    Type: Application
    Filed: April 17, 2013
    Publication date: September 5, 2013
    Applicant: NEC Laboratories America, Inc.
    Inventors: Narayan Prasad, Kishore Ramachandran, SAMPATH RANGARAJAN
  • Robust linear precoder designs for multi-cell downlink transmission
    Patent number: 8520762
    Abstract: Methods and systems for optimizing the utilities of receiver devices in a wireless communication network are disclosed. Precoder design formulations that maximize a minimum worst-case rate or a worst-case sum rate are described for both full base station, cooperation and limited base station cooperation scenarios. In addition, optimal equalizers are also selected to optimize the worst-case sum rate.
    Type: Grant
    Filed: March 7, 2012
    Date of Patent: August 27, 2013
    Assignee: NEC Laboratories America, Inc.
    Inventors: Ali Tajer, Narayan Prasad, Xiaodong Wang, Sampath Rangarajan
  • Robust linear precoder designs for multi-cell downlink transmission
    Patent number: 8520763
    Abstract: Methods and systems for optimizing the utilities of receiver devices in a wireless communication network are disclosed. Precoder design formulations that maximize a minimum worst-case rate or a worst-case sum rate are described for both full base station cooperation and limited base station cooperation scenarios. In addition, optimal equalizers are also selected to optimize the worst-case sum rate.
    Type: Grant
    Filed: October 12, 2012
    Date of Patent: August 27, 2013
    Assignee: NEC Laboratories America, Inc.
    Inventors: Ali Tajer, Narayan Prasad, Xiaodong Wang, Sampath Rangarajan
  • Methods and systems for dynamic and configuration based fractional frequency reuse for uneven load distributions
    Patent number: 8521173
    Abstract: Fractional frequency reuse systems and methods for assigning physical resource units of an available frequency band to sectors of cells are disclosed. In particular, the systems and methods permit adaptation of frequency configuration partitions to mobile station or throughput distribution within cells while at the same time ensuring mitigation of interference between neighboring sectors of different cells.
    Type: Grant
    Filed: March 12, 2010
    Date of Patent: August 27, 2013
    Assignee: NEC Laboratories America, Inc.
    Inventors: Honghai Zhang, Narayan Prasad, Sampath Rangarajan
  • Beam combination methods and systems for adapting communication links to varying channel conditions
    Patent number: 8510433
    Abstract: Methods and systems for rectifying deteriorated channel conditions on a communication link are described. In response to the detection of a link deterioration event, a cluster of beams about a currently utilized beam pair can be trialed to determine a suitable, alternate pair of beams on which to establish a communication link. In turn, in the case of a link blockage event, a set of beams having a relatively large azimuthal angle with respect to a currently utilized beam pair can be trialed to determine a suitable beam pair for further communication.
    Type: Grant
    Filed: November 8, 2010
    Date of Patent: August 13, 2013
    Assignee: NEC Laboratories America, Inc.
    Inventors: Kishore Ramachandran, Narayan Prasad, Sampath Rangarajan
  • Selective joint demodulation
    Patent number: 8503554
    Abstract: Systems, methods and apparatuses for jointly demodulating data signals are disclosed. In accordance with the method, pilot signals are received from a base station and are processed. In addition, from a set of expected co-scheduled data streams, a subset of the co-scheduled data streams that are actually transmitted by the base station are determined based on the pilot signals. Further, a group of the transmitted co-scheduled data streams are selected from the determined subset. The data signals are received and jointly demodulated by employing the selected group of co-scheduled data streams and by suppressing non-selected data streams from the determined subset.
    Type: Grant
    Filed: April 18, 2011
    Date of Patent: August 6, 2013
    Assignee: NEC Laboratories America, Inc.
    Inventors: Narayan Prasad, Guosen Yue, Mohammad A. Khojastepour, Meilong Jiang, Sampath Rangarajan
  • Wideband codebook construction and applications
    Patent number: 8494459
    Abstract: A precoding scheme in which the downlink channel is estimated and an optimal precoding matrix to be used by the multi antenna transmitter is determined accordingly. The optimal precoding matrix is selected from a codebook of matrices that includes matrices having a structure matched to that of the eigenvectors of the spatial covariance matrix, wherein the spatial covariance matrix is modeled as a Hermitian and Toeplitz matrix parameterized by a single complex-valued scalar.
    Type: Grant
    Filed: August 19, 2011
    Date of Patent: July 23, 2013
    Assignee: NEC Laboratories America, Inc.
    Inventors: Narayan Prasad, Mohammad Amir Khojastepour, Sampath Rangarajan
  • Coordinated linear beamforming in downlink multi-cell wireless networks
    Patent number: 8488440
    Abstract: System and methods are disclosed for optimizing wireless communication for a plurality of mobile wireless devices. The system uses beamforming vectors or precoders having a structure optimal with respect to the weighted sum rate in a multi-cell orthogonal frequency division multiple access (OFDMA) downlink. A plurality of base stations communicate with the mobile devices and all base stations perform a distributed non-convex optimization exploiting the determined structure.
    Type: Grant
    Filed: March 7, 2012
    Date of Patent: July 16, 2013
    Assignee: NEC Laboratories America, Inc.
    Inventors: Luca Venturino, Xiaodong Wang, Narayan Prasad
  • Coordinated linear beamforming in downlink multi-cell wireless networks
    Patent number: 8488441
    Abstract: System and methods are disclosed for optimizing wireless communication for a plurality of mobile wireless devices. The system uses beamforming vectors or precoders having a structure optimal with respect to the weighted sum rate in a multi-cell orthogonal frequency division multiple access (OFDMA) downlink. A plurality of base stations communicate with the mobile devices and all base stations perform a distributed non-convex optimization exploiting the determined structure.
    Type: Grant
    Filed: March 7, 2012
    Date of Patent: July 16, 2013
    Assignee: NEC Laboratories America, Inc.
    Inventors: Luca Venturino, Xiaodong Wang, Narayan Prasad
  • Precoder Design for Physical Layer Multicasting
    Publication number: 20130170422
    Abstract: A method for a transmit precoder for multicast communication over a downlink in a wireless network, including: initializing a transmit precoder, a channel estimate for each user in the wireless network; updating for each user a receive filter and a slack matrix; updating the transmit precoder by solving a second order cone routine solvable in closed form; determining if a predetermined convergence is met; and outputting the updated transmit precoder responsive to the convergence criteria.
    Type: Application
    Filed: September 17, 2012
    Publication date: July 4, 2013
    Applicant: NEC LABORATORIES AMERICA, INC.
    Inventors: Narayan Prasad, Hao Zhu, Sampath Rangarajan
  • MULTI-USER SCHEDULING IN CELLULAR UPLINKS
    Publication number: 20130170366
    Abstract: Disclosed herein are techniques, methods, and apparatus pertaining to a multi-user scheduling in 4G and 3GPP LTE cellular uplinks.
    Type: Application
    Filed: July 30, 2012
    Publication date: July 4, 2013
    Applicant: NEC Laboratories America, Inc.
    Inventors: Narayan PRASAD, Honghai ZHANG, Sampath RANGARAJAN
  • Computationally-efficient MIMO equalization algorithm for high-speed, real-time, adaptive polarization multiplexed (POLMUX) OFDM transmission with direct detection
    Patent number: 8472813
    Abstract: A polarization-multiplexed (POLMUX) optical orthogonal frequency division multiplexing (OFDM) system with direct detection includes an adaptive dual POLMUX carrier OFDM transmitter; and a block symmetric (B-S) MIMO equalizer coupled to the adaptive dual POLMUX carrier OFDM transmitter through a standard single-mode-fiber (SSMF) feedback path.
    Type: Grant
    Filed: June 18, 2010
    Date of Patent: June 25, 2013
    Assignee: NEC Laboratories America, Inc.
    Inventors: Neda Cvijetic, Narayan Prasad, Dayou Qian, Ting Wang