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).

  • Publication number: 20150381335
    Abstract: A method implemented in an access point (AP) used in a wireless communications system including a first uplink (UL) client device, a second UL client device, and a first downlink (DL) client device is disclosed. The method comprises: receiving, from the first DL client device, first composite channel matrix M1 comprising a first channel matrix and a second channel matrix, wherein the first DL client device estimates the first channel matrix and the second channel matrix. Other methods, systems, and apparatuses also are disclosed.
    Type: Application
    Filed: August 5, 2015
    Publication date: December 31, 2015
    Inventors: Mohammad Khojastepour, Karthikeyan Sundaresan, Eugene Chai, Sampath Rangarajan
  • Publication number: 20150372743
    Abstract: Systems and methods for full-duplex communication in a communications network, including generating a combined channel matrix including two or more channel matrices and determining a null space and a basis for the combined channel matrix. Common, individual, and disjoint vector spaces are determined, and common vector space is determined for each of one or more receiving nodes and each or one or more transmitting nodes, disjoint vector spaces for each of the one or more nodes are determined based on the common vector space for each of the one or more nodes, and individual vector spaces are determined based on the common and the disjoint vector spaces. Signals are mapped at each of the nodes to determine corresponding vector spaces; and interference alignment is performed in common vector spaces and zero forcing in disjoint vector spaces using a hardware processor.
    Type: Application
    Filed: June 17, 2015
    Publication date: December 24, 2015
    Inventors: Mohammad Khojastepour, Karthikeyan Sundaresan
  • Publication number: 20150365143
    Abstract: Methods and systems for beam forming, implemented in a base station used in a communication system, include measuring channel state information (CSI) for a number of active phased-array antennas less than a full number of phased-array antennas. Analog beam forming weights are determined using the measured CSI. An optimal digital precoder is determined from the analog beam forming weights. The analog beam forming weights and optimal digital precoder are applied to one phased-array antenna.
    Type: Application
    Filed: June 12, 2015
    Publication date: December 17, 2015
    Inventors: Eugene Chai, Xiufeng Xie, Mohammad Khojastepour, Karthikeyan Sundaresan, Sampath Rangarajan
  • Publication number: 20150365142
    Abstract: Methods and systems for beam forming include measuring channel state information for a set of different codebook entries. An angle of arrival (AoA) distribution is determined with a processor using compressive testing based on the measured channel state information. A set of phase shift values is determined based on the determined AoA to perform phased array beamforming.
    Type: Application
    Filed: June 12, 2015
    Publication date: December 17, 2015
    Inventors: Eugene Chai, Xiufeng Xie, Mohammad Khojastepour, Karthikeyan Sundaresan, Sampath Rangarajan
  • Patent number: 9184902
    Abstract: A communications apparatus used in a wireless full duplex system is disclosed. The communications apparatus includes a receiver chain connected to an antenna and an interference cancelling chain. One or more cancellation signals generated by the interference cancelling chain are fed back to the receiver chain prior to the first baseband amplifier which uses the first automatic gain control and the second automatic gain controller. Other methods and systems also are disclosed.
    Type: Grant
    Filed: April 24, 2013
    Date of Patent: November 10, 2015
    Assignee: NEC Laboratories America, Inc.
    Inventors: Mohammad Khojastepour, Sampath Rangarajan
  • Publication number: 20150312903
    Abstract: In a wireless communications system including a first transmission point and a second transmission point, a wireless communications method implemented in the first transmission point supporting coordinated multi-point transmission and reception (CoMP) is disclosed. The wireless communications method comprises transmitting to the second transmission point one or more CoMP hypothesis sets, and transmitting to the second transmission point a benefit metric corresponding to each CoMP hypothesis set, wherein the benefit metric can be a negative value. Other methods, systems, and apparatuses also are disclosed.
    Type: Application
    Filed: March 18, 2015
    Publication date: October 29, 2015
    Inventors: Narayan Prasad, Mohammad Khojastepour, Mustafa Arslan, Karthikeyan Sundaresan, Sampath Rangarajan
  • Publication number: 20150312893
    Abstract: A wireless communications method implemented in a transmission point (TP) used in a wireless communications system is disclosed. The wireless communications method comprises receiving, from another TP, channel state information (CSI) for a user equipment (UE), and receiving, from said another TP, user identification for the user equipment, wherein the signaling of the CSI for the user equipment enables user identification for the user equipment. Other methods, systems, and apparatuses also are disclosed.
    Type: Application
    Filed: March 18, 2015
    Publication date: October 29, 2015
    Inventors: Narayan Prasad, Mohammad Khojastepour, Mustafa Arslan, Karthikeyan Sundaresan, Sampath Rangarajan
  • 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: 9124360
    Abstract: Systems and methods are disclosed to operate a communication network by dividing signal dimensions at a receiver into interference and intended signal dimensions; applying transmit precoding to mitigate interference by overlapping the interference from a plurality of transmitters into the interference dimension at the receiver; and applying a receiver filter to cancel out the interference dimension at the receiver and recover the signal in the intended signal dimension.
    Type: Grant
    Filed: December 4, 2014
    Date of Patent: September 1, 2015
    Assignee: NEC Laboratories America, Inc.
    Inventor: Mohammad Khojastepour
  • Publication number: 20150223173
    Abstract: An interference alignment system for communication structures that includes a single cell channel comprising an access point node, and a full bipartite interference channel (FBIC) configuration of a plurality of receiving nodes and a plurality of transmitting nodes. Each receiving node sees an interfering signal from all transmitting nodes. The access point node of the single cell channel provides a single node having downlink channels to all receiving nodes in the FBIC, and all of the uplink channels from the FBIC are to the single access point node to the single cell channel.
    Type: Application
    Filed: December 4, 2014
    Publication date: August 6, 2015
    Inventors: Mohammad Khojastepour, KARTHIKEYAN SUNDARESAN, Eugene Chai, Sampath Rangarajan
  • Publication number: 20150200733
    Abstract: Systems and methods are disclosed to operate a communication network by dividing signal dimensions at a receiver into interference and intended signal dimensions; applying transmit precoding to mitigate interference by overlapping the interference from a plurality of transmitters into the interference dimension at thea receiver; and applying a receiver filter to cancel out the interference dimension at the receiver and recover the signal in the intended signal dimension.
    Type: Application
    Filed: December 4, 2014
    Publication date: July 16, 2015
    Inventor: Mohammad Khojastepour
  • 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
  • Publication number: 20150117562
    Abstract: A wireless communications method implemented in a transmission point (TP) used in a mobile communications system is disclosed. The wireless communications method includes receiving, from another TP, short-term channel state information (short-term CSI), and processing the short-term CSI. Other methods, systems, and apparatuses also are disclosed.
    Type: Application
    Filed: October 30, 2014
    Publication date: April 30, 2015
    Inventors: Narayan Prasad, I, Mohammad Khojastepour, Mustafa Arslan, Karthikeyan Sundaresan, Sampath Rangarajan
  • Publication number: 20150117370
    Abstract: A wireless communications method implemented in a transmission point (TP) used in a mobile communications system is disclosed. The wireless communications method includes receiving, from a user equipment (UE), short-term channel state information (short-term CSI), processing the short-term CSI, and transmitting, to another TP, the processed short-term CSI. Other methods, systems, and apparatuses also are disclosed.
    Type: Application
    Filed: October 30, 2014
    Publication date: April 30, 2015
    Inventors: Narayan Prasad, I, Mohammad Khojastepour, Mustafa Arslan, Karthikeyan Sundaresan, Sampath Rangarajan
  • Patent number: 9020061
    Abstract: A method implemented in a base station used in a wireless communications system is disclosed. The method comprises having a codebook including a plurality of precoding matrices, precoding data with one of the plurality of precoding matrices, and transmitting, to a user equipment, the precoded data, wherein each precoding matrix W satisfies W=W(1)W(2), where first matrix W(1) is chosen from first codebook (1), and second matrix W(2) is chosen from a second codebook. Other apparatuses, systems, and methods also are disclosed.
    Type: Grant
    Filed: March 6, 2014
    Date of Patent: April 28, 2015
    Assignee: NEC Laboratories America, Inc.
    Inventors: Narayan Prasad, Guosen Yue, Mohammad 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