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: 20150029904
    Abstract: Methods are provided for converting from half-duplex communication to full-duplex communication in a legacy wireless cellular system having a base station. A method includes providing in the base station separate transmit and receive paths for transmit signals and receive signals, respectively. The method further includes converting an uplink frequency band and a downlink frequency band for the base station to a same frequency band. The method also includes applying analog signal cancellation techniques at the base station to isolate a full-duplex wireless reception signal from a full-duplex wireless transmission signal.
    Type: Application
    Filed: July 17, 2014
    Publication date: January 29, 2015
    Inventors: Mohammad Khojastepour, Karthikeyan Sundaresan, Sampath Rangarajan
  • Publication number: 20150023248
    Abstract: A system and a method are provided. The method includes deploying a plurality of antennas of an access point or a base station as a distributed antenna system. The method further includes configuring the distributed antenna system for multi-user wireless transmissions by applying medium access techniques and power-balanced pre-coding at the access point or the base station. The method also includes providing device localization for devices communicating with the distributed antenna system by applying time-difference-of-arrival techniques to antenna pairs from among the plurality of antennas at the access point or the base station.
    Type: Application
    Filed: July 16, 2014
    Publication date: January 22, 2015
    Inventors: Karthikeyan Sundaresan, Mohammad Khojastepour, Sampath Rangarajan, Jie Xiong
  • 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
  • Publication number: 20140269323
    Abstract: Systems and methods for adaptive video delivery over a network, including receiving a plurality of types of data flows from one or more network base stations; separating resource management of the plurality of types of data flows, wherein the data flows include one or more of adaptive video streaming flows, regular video traffic flows, and other traffic flows by resource slicing. A scheduling framework for adaptive video delivery is instantiated; available choices of video bit rates for all users is received as input to an allocator; optimal allocation of resources is computed for all users by determining and selecting an optimal bit rate for each user using the allocator; the optimal bit rate being sent to an enforcer; resources across flows are isolated using the enforcer; and the optimal bit rate for each user is enforced using per-flow traffic shapers to maximize resource utilization without reaching network capacity.
    Type: Application
    Filed: March 14, 2014
    Publication date: September 18, 2014
    Applicant: NEC Laboratories America, Inc.
    Inventors: Rajesh MAHINDRA, MOHAMMAD KHOJASTEPOUR, SAMPATH RANGARAJAN, JIASI CHEN
  • 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: 20140241449
    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: Application
    Filed: March 6, 2014
    Publication date: August 28, 2014
    Applicant: NEC Laboratories America, Inc.
    Inventors: Narayan Prasad, Guosen Yue, Mohammad Khojastepour, Sampath Rangarajan
  • Publication number: 20140241450
    Abstract: A method implemented in a base station used in a wireless communications system is disclosed. The method comprises having 1-layer, 2-layer, 3-layer, and 4-layer codebooks for 4 transmit antenna (4TX) transmission, each 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 of the 1-layer and 2-layer codebooks comprises a first codebook and a second codebook, and wherein each precoding matrix in the first codebook comprises a first index and a second index. Other apparatuses, systems, and methods also are disclosed.
    Type: Application
    Filed: March 11, 2014
    Publication date: August 28, 2014
    Applicant: NEC LABORATORIES AMERICA, INC.
    Inventors: Narayan Prasad, Guosen Yue, Mohammad Khojastepour, 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
  • Patent number: 8761129
    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 based on a residual error.
    Type: Grant
    Filed: April 26, 2012
    Date of Patent: June 24, 2014
    Assignee: NEC Laboratories America, Inc.
    Inventors: Narayan Prasad, Guosen Yue, Meilong Jiang, Mohammad A. Khojastepour, Sampath Rangarajan
  • Patent number: 8750358
    Abstract: A method for improving multiple-input multiple-output MIMO downlink transmissions includes obtaining a channel state information CSI report including preferred matrix index PMI for precoding, channel quality index CQI and rank index RI at a base station from user terminals through a channel feedback; applying selectively a signal-to-interference-plus-noise-ratio SINR offset to a SINR of said CSI report; applying selectively a rate matching responsive to SINR offset or the CSI report; and controlling or adjusting the SINR offset.
    Type: Grant
    Filed: April 6, 2012
    Date of Patent: June 10, 2014
    Assignee: NEC Laboratories America, Inc.
    Inventors: Guosen Yue, Narayan Prasad, Meilong Jiang, Mohammad A. Khojastepour, Sampath Rangarajan
  • Publication number: 20140140428
    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: Application
    Filed: November 18, 2013
    Publication date: May 22, 2014
    Applicant: NEC Laboratories America, Inc.
    Inventors: Mohammad A. Khojastepour, Sampath Rangarajan
  • Patent number: 8718156
    Abstract: Methods and systems for indexing signal option selections are disclosed. The signal options can be any of a variety of options that permit the establishment of a communication link, including modulation format, coding rate, precoding index and assigned subbands. The selected options can be represented as a vector and the index can be determined by employing a worth function for a particular selected vector element that is dependent on a selection occurrence count of the element and on an element position count of the element. In particular, the index can be the summation of worth function values for each selected element.
    Type: Grant
    Filed: November 5, 2010
    Date of Patent: May 6, 2014
    Assignee: NEC Laboratories America, Inc.
    Inventors: Mohammad A. Khojastepour, Sampath Rangarajan