Patents by Inventor Sampath Rangarajan

Sampath Rangarajan 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: 20180084532
    Abstract: A computer-implemented method is provided for downlink scheduling in a MU-MIMO telecommunication system. The method includes identifying for each of multiple virtual users which collectively form a ground set of virtual users, a respective transmit precoder and receive beamformer combination that maximizes a difference between two submodular set functions applied over the ground set of virtual users, from among a plurality of combinations formed from a respective one of a plurality of transmit precoders and a respective one of a plurality of receive beamformers. The method includes transmitting data from at least some multiple virtual users, based on a downlink transmission schedule determined from the respective transmit precoder and receive beamformer combination identified for the at least some multiple virtual users. The ground set is formed from respective combinations of multiple actual users and the plurality of receive beamformers.
    Type: Application
    Filed: August 14, 2017
    Publication date: March 22, 2018
    Inventors: Narayan Prasad, Yasaman Ghasempour, Mohammad Khojastepour, Sampath Rangarajan
  • Publication number: 20180084600
    Abstract: A computer-implemented method for establishing communication links in a millimeter wave (mmWave) network by solving a linear integer packing problem is presented. The computer-implemented method includes determining active communication links between a plurality of transmitters and a plurality of receivers, setting each active communication link to have any arbitrary chosen weight or priority, and setting a minimum link quality threshold for each active communication link and subjecting each active communication link to constraints. Detected phantom constraints are mitigated by introducing new constraints with binary coefficients and by modifying one or more existing constraints by setting a number of coefficients within the existing constraints to zero.
    Type: Application
    Filed: August 16, 2017
    Publication date: March 22, 2018
    Inventors: Narayan Prasad, Mohammad Khojastepour, Sampath Rangarajan, Yasaman Ghasempour
  • Patent number: 9906340
    Abstract: A method and transmitting device are provided for coordinated multi-point transmission scheduling by a transmitting device over one or more heterogeneous wireless networks that include a set of clusters. Each of the clusters has a set of transmission points for serving a set of user equipment devices. The method includes determining constraints imposed on any of the user equipment devices. The method further includes receiving channel state information feedback from the user equipment devices. The method also includes obtaining user weights and buffer sizes. The method additionally includes iteratively determining a weighted sum of user rates based on the constraints, the channel state information feedback, the user weights, and the buffer sizes. The iteratively determining step determines the weighted sum of user rates based on an initial weighted sum of user rates determined for the user equipment devices without the constraints.
    Type: Grant
    Filed: February 4, 2016
    Date of Patent: February 27, 2018
    Assignee: NEC Corporation
    Inventors: Narayan Prasad, Sampath Rangarajan, Yasushi Maruta, Duong Pham, Arun Gurung, Caroline Liang, Patricia Wells, Robert Arnott
  • Patent number: 9888469
    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: Grant
    Filed: March 18, 2015
    Date of Patent: February 6, 2018
    Assignee: NEC Corporation
    Inventors: Narayan Prasad, Mohammad Khojastepour, Mustafa Arslan, Karthikeyan Sundaresan, Sampath Rangarajan
  • Patent number: 9847818
    Abstract: A method implemented in a base station used in a wireless communications system is disclosed. The method comprises receiving, from a user equipment, rank indication (RI), a first precoding matrix indicator (PMI), and a second PMI (codebook index i2), wherein values 0-15 are assigned to the second PMI IPMI2 for RI=1 and values 0-3 are assigned to the second PMI IPMI2 for each of RI=2, RI=3, and RI=4, and wherein codebook index i2 comprises IPMI2 for RI=1. Other methods, apparatuses, and systems also are disclosed.
    Type: Grant
    Filed: June 4, 2014
    Date of Patent: December 19, 2017
    Assignee: NEC Corporation
    Inventors: Guosen Yue, Narayan Prasad, Sampath Rangarajan
  • Publication number: 20170324456
    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: July 26, 2017
    Publication date: November 9, 2017
    Applicant: NEC Corporation
    Inventors: Narayan PRASAD, Guosen YUE, Mohammad KHOJASTEPOUR, Sampath RANGARAJAN
  • Patent number: 9813995
    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: Grant
    Filed: August 5, 2015
    Date of Patent: November 7, 2017
    Assignee: NEC CORPORATION
    Inventors: Mohammad Khojastepour, Karthikeyan Sundaresan, Eugene Chai, Sampath Rangarajan
  • Patent number: 9813922
    Abstract: A system and method for resource management in a heterogeneous wireless network wherein the resources of the mobile communications system are managed on a coarse time-scale and a fine time-scale. The coarse time-scale management comprises a first stage of determining the user association for each of the plurality of TPs followed by a second stage of determining activation fractions for all TPs. The determining of the user association is performed by utilizing a GLS procedure having a Greedy Stage and a Local Search Stage. In the Greedy Stage, new user, TP pairs are analyzed and the pair with the greatest improvement in system utility is selected. In the Local Search Stage, potential swaps are analyzed and a pair offering the greatest improvement that exceeds a threshold is selected. The determining of activation fractions for all TPs is performed by utilizing an auxiliary function method.
    Type: Grant
    Filed: July 29, 2015
    Date of Patent: November 7, 2017
    Assignee: NEC Corporation
    Inventors: Narayan Prasad, Vaibhav Singh, Sampath Rangarajan
  • Publication number: 20170318601
    Abstract: Methods and a system are provided for enhanced long-term evolution scheduling. A ranking is constructed for one or more users scheduled on one or more resource blocks. A layer mapping is generated, using a finite modulation and coding scheme, utilizing the ranking of each of the one or more users for the one or more resource blocks. An enhanced ranking is determined, using a finite constraint on a buffer for each of the one or more users, for the one or more resource blocks utilizing the layer mapping. The enhanced ranking is deployed into a schedule for the one or more resource blocks being utilized by each of the one or more users. Bandwidth usage is optimized in the one or more resource blocks by utilizing the schedule.
    Type: Application
    Filed: May 1, 2017
    Publication date: November 2, 2017
    Inventors: Narayan Prasad, Sampath Rangarajan, Patricia Wells, Robert Arnott
  • Publication number: 20170303296
    Abstract: A computer-implemented method for associating users to transmission points over an uplink (UL) of a heterogeneous network (HetNet) is presented. The computer-implemented method includes communicating, via the processor, with a cluster of transmission points, associating each user to one transmission point within the cluster of transmission points by a two-stage procedure, and performing sub-frame scheduling independently by each transmission point within the cluster of transmission points over a set of users associated with.
    Type: Application
    Filed: April 12, 2017
    Publication date: October 19, 2017
    Inventors: Narayan Prasad, Sampath Rangarajan, Caroline Liang
  • Publication number: 20170265083
    Abstract: Methods and a system are provided for enabling coexistence of WIFI and Long Term Evolution (LTE) in a wireless communication system. A method includes embedding in a data sequence, by a base station capable of transmitting and receiving LTE frames, a channel reservation packet that (i) is detectable by a WIFI receiver and (ii) reserves a particular one of a plurality of available unlicensed communication channels for a transmission duration of the data sequence. The method further includes transmitting, by the base station, the data sequence including the embedded channel reservation packet.
    Type: Application
    Filed: February 1, 2017
    Publication date: September 14, 2017
    Inventors: Mohammad Khojastepour, Eugene Chai, Karthikeyan Sundaresan, Sampath Rangarajan
  • Patent number: 9755716
    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: Grant
    Filed: May 2, 2016
    Date of Patent: September 5, 2017
    Assignee: NEC Corporation
    Inventors: Narayan Prasad, Guosen Yue, Mohammad Khojastepour, Sampath Rangarajan
  • Patent number: 9736785
    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: Grant
    Filed: December 4, 2014
    Date of Patent: August 15, 2017
    Assignee: NEC Corporation
    Inventors: Mohammad Khojastepour, Karthikeyan Sundaresan, Eugene Chai, Sampath Rangarajan
  • Patent number: 9723532
    Abstract: A system for traffic management between a WiFi network and an LTE network that includes a network interface assignment module for determining from an operator side of the WiFi network and the LTE network a set of WiFi Access Points (APs) and LTE base stations for each user that provides a least a highest quality of experience for each of the users using input strength for all users to potential WiFi access points and LTE base stations. The system may further include an interface switching service (ISS) module that includes a control logic and a network HTTP proxy for delivering network switching instructions to devices of users. The control logic receiving instructions from the NIA module and sending signal to the devices of the users to switch from WIFI and LTE networks through the LTE network based upon signal strength of the users.
    Type: Grant
    Filed: December 9, 2014
    Date of Patent: August 1, 2017
    Assignee: NEC Corporation
    Inventors: Rajesh Mahindra, Karthikeyan Sundaresan, Mustafa Arslan, Sampath Rangarajan, Hariharasudhan Viswanathan
  • Patent number: 9722725
    Abstract: A system and method for resource management in a heterogeneous wireless network that is performed via distributed implementation wherein the resources of the mobile communications system are managed on a coarse time-scale and a fine time-scale. The coarse time-scale management comprises a first stage of determining the user association for each of the TPs followed by a second stage of determining activation fractions for all TPs. The determining of the user association is performed by utilizing a GLS procedure having a Greedy Stage and a Local Search Stage. In the Greedy Stage, new user, TP pairs are analyzed and the pair with the greatest improvement in system utility is selected. In the Local Search Stage, potential swaps are analyzed and a pair offering the greatest improvement that exceeds a threshold is selected. The determining of activation fractions for all TPs is performed by utilizing an auxiliary function method.
    Type: Grant
    Filed: August 28, 2015
    Date of Patent: August 1, 2017
    Assignee: NEC Corporation
    Inventors: Narayan Prasad, Vaibhav Singh, Sampath Rangarajan, Mustafa Arslan
  • Patent number: 9723566
    Abstract: A method implemented in a wireless communications system including a first uplink (UL) client device, a second UL client device, a first downlink (DL) client device, and an access point (AP) is disclosed. The method comprises the following steps in this order: a) determining interference alignment (IA) solution between the first and second UL client devices and the first device; and b) determining, according to the IA solution, receive filter U0 for the AP and precoder V0 for the AP to improve a UL stream rate and a DL stream rate. Other methods, systems, and apparatuses also are disclosed.
    Type: Grant
    Filed: August 5, 2015
    Date of Patent: August 1, 2017
    Assignee: NEC Corporation
    Inventors: Mohammad Khojastepour, Karthikeyan Sundaresan, Eugene Chai, Sampath Rangarajan
  • Patent number: 9723567
    Abstract: A method implemented in an access point (AP) having N antennas used in a wireless communications system including two first client devices each of which has M antennas and two second client devices each of which has N antennas, where M and N are even is disclosed. The method comprises: performing interference alignment (IA) in common vector spaces; and delivering M+N streams. Other methods, systems, and apparatuses also are disclosed.
    Type: Grant
    Filed: August 5, 2015
    Date of Patent: August 1, 2017
    Assignee: NEC Corporation
    Inventors: Mohammad Khojastepour, Karthikeyan Sundaresan, Eugene Chai, Sampath Rangarajan
  • Patent number: 9722720
    Abstract: A method, system, and computer program product for minimizing intra-cell and inter-cell interference in a multi-cell full duplex communication system in a wireless network. The method includes selecting, by a client selector, a plurality of clients, wherein the plurality of clients includes a plurality of uplink clients configured to transmit signals and a plurality of downlink clients configured to receive signals over a plurality of data streams in each cell of the multi-cell full duplex communication system, and performing, by a spatial interference aligner, spatial interference alignment on interfering data streams to align the interfering data streams of uplink clients towards downlink clients in its own cell and downlink clients in a neighboring cell.
    Type: Grant
    Filed: July 28, 2015
    Date of Patent: August 1, 2017
    Assignee: NEC Corporation
    Inventors: Mohammad Khojastepour, Karthikeyan Sundaresan, Sampath Rangarajan
  • Publication number: 20170161109
    Abstract: Computer-implemented methods and a system are provided for distributing tasks between a plurality of processes in a computer network. A method includes distributing, by a load balancer in the computer network, tasks between the plurality of processes. The method further includes maintaining, by the load balancer, a registry for each of the tasks. For a given task, the registry indicates which of the plurality of processes to which the given task is distributed based on a hash function. The method also includes forming, by the load balancer, a respective set of registries for each of the plurality of processes, based on a set of thresholds. The method additionally includes redefining, by the load balancer, the set of thresholds when one of the plurality of processes ceases or a new process, added to the plurality of processes, commences.
    Type: Application
    Filed: November 28, 2016
    Publication date: June 8, 2017
    Inventors: Mohammad Khojastepour, Rajesh Mahindra, Sampath Rangarajan, Karthikeyan Sundaresan
  • Patent number: 9654174
    Abstract: A method for managing a power line communication network in a multi-flow environment. The method includes determining an average throughput between each pair of nodes acting in isolation within the power line communication network, defining logical zones by grouping each pair of nodes if the average throughput between the pair of nodes exceeds a first threshold, wherein the logical zones include a plurality of strongly coupled zones. The method further includes determining an aggregate throughput for a pair of flows between randomly selected pairs of nodes acting concurrently between the plurality of strongly coupled zones, determining a plurality of pair of flows that can be concurrently operated when the aggregate throughput exceeds the average throughput, estimating a resulting throughput of the plurality of pair of flows that can be concurrently operated, and optimizing a schedule for the plurality of pair of flows based on the resulting throughput.
    Type: Grant
    Filed: September 4, 2015
    Date of Patent: May 16, 2017
    Assignee: NEC Corporation
    Inventors: Karthikeyan Sundaresan, Mohammad Khojastepour, Sampath Rangarajan, Ahmed O. F. Atya