Patents by Inventor Mohammad A. Khojastepour

Mohammad A. Khojastepour 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).

  • Patent number: 9532257
    Abstract: A method implemented in a user equipment configured to be used in a multi-user (MU) multiple-input multiple-output (MIMO) wireless communications system is disclosed. The method includes transmitting to a base station a first channel state information (CSI) report determined according to a single-user (SU) MIMO rule, and transmitting to the base station a second CSI report determined according to an MU-MIMO rule. Other methods, apparatuses, and systems also are disclosed.
    Type: Grant
    Filed: August 1, 2014
    Date of Patent: December 27, 2016
    Assignee: NEC Corporation
    Inventors: Narayan Prasad, Guosen Yue, Meilong Jiang, Mohammad A. Khojastepour, Sampath Rangarajan
  • Patent number: 9461722
    Abstract: Methods and apparatus are disclosed for applying successive multi-rank beamforming strategies (e.g., successive precoding strategies) for the design of precoders over a set of parallel channels. Successive beamforming is applied to a narrow band channel model and is also applied for finer quantization of a single beamforming vector (e.g., recursive beamforming). A first embodiment provides the optimal approach with high complexity. An alternative embodiment provides successive beamforming for near optimal precoding selection with medium complexity. A low complexity method for precoder selection is also provided wherein a channel representative matrix for the set of parallel channels is determined and successive beamforming on the calculated channel representative is applied.
    Type: Grant
    Filed: May 31, 2012
    Date of Patent: October 4, 2016
    Assignee: NEC Corporation
    Inventor: Mohammad A. Khojastepour
  • Publication number: 20150288434
    Abstract: A method implemented in a user equipment used in a wireless communications system is disclosed. The method comprises receiving from a base station an indication of a first modulation type for the user equipment, receiving from the base station a first data signal for the user equipment, receiving from the base station an indication of a minimum time-frequency unit that is assigned to another user equipment, receiving a second data signal for said another user equipment, where a second modulation type for said another user equipment is unknown to the user equipment, and cancelling and suppressing interference by using the minimum time-frequency unit. Other methods, systems, and apparatuses also are disclosed.
    Type: Application
    Filed: June 19, 2015
    Publication date: October 8, 2015
    Inventors: Narayan Prasad, Guosen Yue, Mohammad A. Khojastepour, Meilong Jiang, Sampath Rangarajan
  • Patent number: 9137788
    Abstract: An apparatus used in a full duplex multiple-input multiple-output (MIMO) wireless communications system is disclosed. In an aspect, the apparatus includes a plurality of antennas, each of which is connected to a combination of at least a TX (transmit) RF (radio frequency) chain and an RX (receive) RF chain. The plurality of antennas are split into one or more transmit antennas and one or more receive antennas, and the apparatus communicates with another apparatus. Other apparatuses and some methods for wireless communications also are disclosed.
    Type: Grant
    Filed: August 17, 2012
    Date of Patent: September 15, 2015
    Assignee: NEC Laboratories America, Inc.
    Inventors: Mohammad A. Khojastepour, Sanaz Barghi, Karthikeyan Sundaresan, Sampath Rangarajan
  • Patent number: 9124319
    Abstract: A method implemented in a user equipment used in a multi-user multiple input multiple output (MU-MIMO) wireless communications system is disclosed. The method includes receiving from a base station an indication of a first modulation type for the user equipment, receiving a first data signal for the user equipment, receiving a second data signal for a co-scheduled user equipment, where a second modulation type for the co-scheduled user equipment is unknown to the user equipment, and deciding the second modulation type. Other methods, systems, and apparatuses also are disclosed.
    Type: Grant
    Filed: April 22, 2014
    Date of Patent: September 1, 2015
    Assignee: NEC Laboratories America, Inc.
    Inventors: Narayan Prasad, Guosen Yue, Mohammad A. Khojastepour, Meilong Jiang, Sampath Rangarajan
  • Patent number: 9083404
    Abstract: Methods and systems for transmission are shown that include iteratively generating an optimized precoder matrix and optimized linear filters for multiple receivers, where the optimized precoder matrix is based on a linear filter from a previous iteration and the optimized linear filters the multiple receivers are based on a precoder matrix from a previous iteration, precoding an input stream using the iteratively generated optimized precoder matrix to produce transmission streams for the multiple receivers, where at least one receiver has a plurality of associated transmission streams, and transmitting the transmission streams with multiple antennas to the receivers.
    Type: Grant
    Filed: September 16, 2011
    Date of Patent: July 14, 2015
    Assignee: NEC Laboratories America, Inc.
    Inventors: Mohammad A. Khojastepour, Mohammad A. Khajehnejad, Guosen Yue
  • Patent number: 9066351
    Abstract: Systems and methods for data transmission include categorizing users into one of a plurality of profiles using a processor based on device and channel characteristics. Each of the plurality of profiles is mapped to one of a plurality of transmission schemes. Data is combined for a plurality of users categorized with different profiles for data transmission.
    Type: Grant
    Filed: July 19, 2013
    Date of Patent: June 23, 2015
    Assignee: NEC Laboratories America, Inc.
    Inventors: Karthikeyan Sundaresan, Mohammad A. Khojastepour, Sampath Rangarajan
  • Patent number: 9014290
    Abstract: There is provided a method performed by a transmitter in a multi-user communication system. The method includes transmitting a first part of a codeword to a plurality of receivers over a communication channel in a transmission. The method further includes receiving feedback on the transmission of the first part of the codeword. The method also includes providing an artificial channel having channel parameters adjustable responsive to the received feedback. The method additionally includes virtually feeding the artificial channel with the first part of the codeword to generate artificial channel output data. The method further includes encoding a second part of the codeword for transmission to the plurality of receivers over the communication channel responsive to the artificial channel output data. The method also includes transmitting the encoded signals to the plurality of receivers over the communication channel.
    Type: Grant
    Filed: November 18, 2013
    Date of Patent: April 21, 2015
    Assignee: NEC Laboratories America, Inc.
    Inventors: Mohammad A. Khojastepour, Sampath Rangarajan
  • Patent number: 8976759
    Abstract: A method implemented in a base station used for a downlink multi-user (MU) multi-input multi-output (MIMO) system is disclosed. The method includes receiving an indication of a quantized matrix from each of a plurality of scheduled user equipments, precoding data streams for the plurality of scheduled user equipments, transmitting the precoded data to the plurality of scheduled user equipments. Other methods and some apparatuses for wireless communications also are disclosed.
    Type: Grant
    Filed: September 14, 2012
    Date of Patent: March 10, 2015
    Assignee: NEC Laboratories America, Inc.
    Inventors: Mohammad A. Khojastepour, Xiaodong Wang, Mohammad Madihian
  • Patent number: 8923907
    Abstract: Systems and methods for system for channel access adaptation are disclosed. One system includes a plurality of remote antennas and a plurality of access points. The remote antennas transmit data to receivers and obtain channel state information. Additionally, each access point controls a different cluster of the remote antennas and receives the respective channel state information from the remote antennas of the cluster. Further, each access point is configured to, independently from other access points, adapt channel allocations to the remote antennas of the respective cluster based on a tracking of sums of collision loss probabilities. Each given sum is determined by the access point for a different given set of a plurality of sets of cooperating remote antennas in the respective cluster, where each constituent collision loss probability in the given sum is determined by the access point from a different interference clique to which the given set belongs.
    Type: Grant
    Filed: January 31, 2013
    Date of Patent: December 30, 2014
    Assignee: NEC Laboratories America, Inc.
    Inventors: Mohammad A. Khojastepour, Xinyu Zhang, Karthikeyan Sundaresan, Sampath Rangarajan
  • Patent number: 8917789
    Abstract: A method implemented in a base station is disclosed. The method includes precoding data with a precoder, and transmitting the precoded data to a user equipment, and the precoder can be expressed as multiplication OV where V is a first matrix corresponding to a first indication of the precoder for a group of transmitted symbols, and O is a second matrix corresponding to a second indication of the precoder for a variation in a channel. Other methods and apparatuses also are disclosed.
    Type: Grant
    Filed: July 16, 2012
    Date of Patent: December 23, 2014
    Assignee: NEC Laboratories America, Inc.
    Inventor: Mohammad A. Khojastepour
  • Publication number: 20140341064
    Abstract: A method implemented in a user equipment configured to be used in a multi-user (MU) multiple-input multiple-output (MIMO) wireless communications system is disclosed. The method includes transmitting to a base station a first channel state information (CSI) report determined according to a single-user (SU) MIMO rule, and transmitting to the base station a second CSI report determined according to an MU-MIMO rule. Other methods, apparatuses, and systems also are disclosed.
    Type: Application
    Filed: August 1, 2014
    Publication date: November 20, 2014
    Inventors: Narayan Prasad, Guosen Yue, Meilong Jiang, Mohammad A. Khojastepour, Sampath Rangarajan
  • Patent number: 8891604
    Abstract: In a multiple-input multiple-output (MIMO) wireless system supporting Coordinated Multi-Point (CoMP) transmission and having a first base station, a second base station, and a user equipment, a communications method implemented in the first base station is disclosed. In an aspect, the communications method includes exchanging, with the second base station through local information exchange, first information about a first channel between the first base station and the user equipment and second information about a second channel between the second base station and the user equipment, and computing at least one of a precoding matrix, a receiver filter, and a projection matrix, wherein the user equipment estimates the first information and the second information, and shares the first information and the second information with the first base station. Other apparatuses and some methods for wireless communications also are disclosed.
    Type: Grant
    Filed: September 27, 2012
    Date of Patent: November 18, 2014
    Assignee: NEC Laboratories America, Inc.
    Inventors: Mohammad A. Khojastepour, Xinyu Zhang, Karthikeyan Sundaresan, Sampath Rangarajan
  • Patent number: 8879433
    Abstract: A method for full duplex communication includes creating a canceling self interference signal using active noise cancelation in the air by using a plurality of transmit antennas and feeding the plurality of antennas with an RF signal in so that part of said RF signal is destructively combined at a receive antenna, and attaining full-duplex simultaneous in time and overlapping in space wireless transmission and reception on same frequency band responsive to the step of creating a canceling self interference signal.
    Type: Grant
    Filed: December 13, 2011
    Date of Patent: November 4, 2014
    Assignee: NEC Laboratories America, Inc.
    Inventors: Mohammad A. Khojastepour, Karthikeyan Sundaresan, Sampath Rangarajan
  • Patent number: 8874125
    Abstract: A method implemented in an apparatus used in a radio access network (RAN) sharing system including a plurality of basestations is disclosed. The method includes estimating resource requirement or demand of one or more entities in each base station according to feedback from the plurality of basestations, computing resource allocation for said one or more entities, and enforcing the computed resource allocation using basestation-level virtualization. Other methods, apparatuses, and systems also are disclosed.
    Type: Grant
    Filed: March 7, 2013
    Date of Patent: October 28, 2014
    Assignee: NEC Laboratories America, Inc.
    Inventors: Rajesh Mahindra, Mohammad A. Khojastepour, Sampath Rangarajan, Honghai Zhang
  • Patent number: 8837332
    Abstract: A method for full duplex communication that includes creating a canceling self interference signal using a passive noise cancellation, and attaining full-duplex simultaneous in time and overlapping in space wireless transmission and reception on same frequency band responsive to the step of creating a canceling self interference signal.
    Type: Grant
    Filed: December 13, 2011
    Date of Patent: September 16, 2014
    Assignee: NEC Laboratories America, Inc.
    Inventors: Mohammad A. Khojastepour, Karthikeyan Sundaresan, Sampath Rangarajan
  • Publication number: 20140233414
    Abstract: A method for determining attributes of communication channels of multi-user (MU)-multiple input multiple output (MIMO) users in an orthogonal frequency division multiplexing based multiple access (OFDMA) system is disclosed. The method comprises receiving from a base station, for at least one sub-band of contiguous sub-carriers, an indication of an estimate of or an upper-bound on a total number of streams that are co-scheduled by the base station on the at least one sub-band or an indication of a fraction of a transmit power at the base station that is applied to streams that are scheduled for transmission to a particular user, determining one or more signal quality measures for the at least one sub-band based on at least one of the fraction or the estimate of or the upper-bound on the total number of streams that are scheduled by the base station on the at least one sub-band, and transmitting to the base station an indication of the one or more signal quality measures.
    Type: Application
    Filed: April 8, 2014
    Publication date: August 21, 2014
    Applicant: NEC Laboratories America, Inc.
    Inventors: Narayan Prasad, Guosen Yue, Mohammad A. Khojastepour, Meilong Jiang, Sampath Rangarajan
  • Publication number: 20140226745
    Abstract: A method implemented in a user equipment used in a multi-user multiple input multiple output (MU-MIMO) wireless communications system is disclosed. The method includes receiving from a base station an indication of a first modulation type for the user equipment, receiving a first data signal for the user equipment, receiving a second data signal for a co-scheduled user equipment, where a second modulation type for the co-scheduled user equipment is unknown to the user equipment, and deciding the second modulation type. Other methods, systems, and apparatuses also are disclosed.
    Type: Application
    Filed: April 22, 2014
    Publication date: August 14, 2014
    Applicant: NEC Laboratories America, Inc.
    Inventors: Narayan Prasad, Guosen Yue, Mohammad A. Khojastepour, Meilong Jiang, Sampath Rangarajan
  • Patent number: 8798011
    Abstract: A method implemented in a user equipment configured to be used in a multi-user (MU) multiple-input multiple-output (MIMO) wireless communications system is disclosed. In an aspect, the user equipment transmits to a base station a first channel state information (CSI) report determined according to a single-user (SU) MIMO rule and a second CSI report determined according to an MU-MIMO rule.
    Type: Grant
    Filed: April 26, 2012
    Date of Patent: August 5, 2014
    Assignee: NEC Laboratories America, Inc.
    Inventors: Narayan Prasad, Guosen Yue, Meilong Jiang, Mohammad A. Khojastepour, Sampath Rangarajan
  • Patent number: 8767665
    Abstract: A method implemented in a base station used in a wireless communications system is disclosed. The method comprises transmitting an index indicating data stream parameters, and transmitting an indication of the number of transmit antennas at the base station, wherein the data stream parameters for 8 transmit antennas are indicated by the index according to a first table, and wherein the data stream parameters for 4 transmit antennas are indicated by the index according to a second table. Other methods, apparatuses, and systems also are disclosed.
    Type: Grant
    Filed: August 15, 2013
    Date of Patent: July 1, 2014
    Assignee: NEC Laboratories America, Inc.
    Inventors: Mohammad A. Khojastepour, Narayan Prasad, Sampath Rangarajan