Patents by Inventor Vasanta Chivukula

Vasanta Chivukula 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: 8787340
    Abstract: A method of connection setup in mobile wireless data communications systems is disclosed where the connection setup time is decreased for delay-sensitive communications sessions relative to the normal connection setup time for confidence-dependent communications sessions. This is achieved by performing some of the connection set-up steps for delay-sensitive communications sessions after successfully demodulating a smaller number of indications identifying an access terminal's desired serving resource than would be demodulated in the case of a confidence-dependent communication session prior to performing the same connection set-up steps.
    Type: Grant
    Filed: February 2, 2012
    Date of Patent: July 22, 2014
    Assignee: Ericsson AB
    Inventors: Xixian Chen, Vasanta Chivukula, Weigang Li, Guoqiang Xue, Ryan Santa, Miroslav Budic, Brian Troup, Martin Kendall
  • Patent number: 8699415
    Abstract: A method and system for connection management in a wireless data network, such as a 1xEV-DO network adds connections to new network sectors upon receipt of a connection request from an active terminal, but removes data connections that the active terminal requests to be dropped only after confirmation from the active terminal that a channel allocation message has been received and applied. The active network maintains an active set of connections that is at least as large as the active set maintained by the active terminal and does not initiate a connection termination if no confirmation of the channel allocation message is received. This allows for a reduction in the number of dropped connections.
    Type: Grant
    Filed: May 2, 2011
    Date of Patent: April 15, 2014
    Assignee: Apple Inc.
    Inventors: Xixian Chen, Weigang Li, Vasanta Chivukula, Shiva Mirzaei-Rezaei, Brian Troup, Miroslav Budic, Yong Zhou, Ryan Santa
  • Publication number: 20120127943
    Abstract: A method of connection setup in mobile wireless data communications systems is disclosed where the connection setup time is decreased for delay-sensitive communications sessions relative to the normal connection setup time for confidence-dependent communications sessions. This is achieved by performing some of the connection set-up steps for delay-sensitive communications sessions after successfully demodulating a smaller number of indications identifying an access terminal's desired serving resource than would be demodulated in the case of a confidence-dependent communication session prior to performing the same connection set-up steps.
    Type: Application
    Filed: February 2, 2012
    Publication date: May 24, 2012
    Applicant: ERICSSON AB
    Inventors: Xixian Chen, Vasanta Chivukula, Weigang Li, Guoqiang Xue, Ryan Santa, Miroslav Budic, Brian Troup, Martin Kendall
  • Patent number: 8134963
    Abstract: A method of connection setup in mobile wireless data communications systems is disclosed where the connection setup time is decreased for delay-sensitive communications sessions relative to the normal connection setup time for confidence-dependent communications sessions. This is achieved by performing some of the connection set-up steps for delay-sensitive communications sessions after successfully demodulating a smaller number of indications identifying an access terminal's desired serving resource than would be demodulated in the case of a confidence-dependent communication session prior to performing the same connection set-up steps.
    Type: Grant
    Filed: April 4, 2008
    Date of Patent: March 13, 2012
    Assignee: Ericsson AB
    Inventors: Xixian Chen, Vasanta Chivukula, Weigang Li, Guoqiang Xue, Ryan Santa, Miroslav Budic, Brian Troup, Martin Kendall
  • Publication number: 20110206007
    Abstract: A method and system for connection management in a wireless data network, such as a 1×EV-DO network adds connections to new network sectors upon receipt of a connection request from an active terminal, but removes data connections that the active terminal requests to be dropped only after confirmation from the active terminal that a channel allocation message has been received and applied. The active network maintains an active set of connections that is at least as large as the active set maintained by the active terminal and does not initiate a connection termination if no confirmation of the channel allocation message is received. This allows for a reduction in the number of dropped connections.
    Type: Application
    Filed: May 2, 2011
    Publication date: August 25, 2011
    Applicant: NORTEL NETWORKS LIMITED
    Inventors: Xixian Chen, Weigang Li, Vasanta Chivukula, Shiva Mirzaei-Rezaei, Brian Troup, Miroslav Budic, Yong Zhou, Ryan Santa
  • Patent number: 7936720
    Abstract: A method and system for connection management in a wireless data network, such as a 1xEV-DO network adds connections to new network sectors upon receipt of a connection request from an active terminal, but removes data connections that the active terminal requests to be dropped only after confirmation from the active terminal that a channel allocation message has been received and applied. The active network maintains an active set of connections that is at least as large as the active set maintained by the active terminal and does not initiate a connection termination if no confirmation of the channel allocation message is received. This allows for a reduction in the number of dropped connections.
    Type: Grant
    Filed: April 28, 2006
    Date of Patent: May 3, 2011
    Assignee: Nortel Networks Limited
    Inventors: Xixian Chen, Weigang Li, Vasanta Chivukula, Shiva Mirzaei-Rezaei, Brian Troup, Miroslav Budic, Yong Zhou, Ryan Santa
  • Publication number: 20060245407
    Abstract: A method and system for connection management in a wireless data network, such as a 1xEV-DO network adds connections to new network sectors upon receipt of a connection request from an active terminal, but removes data connections that the active terminal requests to be dropped only after confirmation from the active terminal that a channel allocation message has been received and applied. The active network maintains an active set of connections that is at least as large as the active set maintained by the active terminal and does not initiate a connection termination if no confirmation of the channel allocation message is received. This allows for a reduction in the number of dropped connections.
    Type: Application
    Filed: April 28, 2006
    Publication date: November 2, 2006
    Applicant: NORTEL NETWORKS LIMITED
    Inventors: Xixian Chen, Weigang Li, Vasanta Chivukula, Shiva Mirzaei-Rezaei, Brian Troup, Miroslav Budic, Yong Zhou, Ryan Santa
  • Patent number: 6337032
    Abstract: A sol-gel precursor mixture for forming a perovskite ferroelectric material and a method for forming a ferroelectric material are provided. The precursor solution comprises a sol-gel formulation of a mixture of an inorganic salt of at least one metal, and metal-organic compounds of other constituent metals in a suitable pH controlled aqueous solvent mixture to form a stable, clear sol-gel mixture. The precursor solution and method provides for formation of thin layers of other ferroelectric dielectrics and piezoelectric materials, particularly lead containing materials, for application including non-volatile DRAMs, optoelectronic devices relying on non-linear optical properties, and piezoelectric devices, and is compatible with processing for submicron device structures for bipolar, CMOS or bipolar CMOS circuits.
    Type: Grant
    Filed: February 16, 2000
    Date of Patent: January 8, 2002
    Assignees: Nortel Networks Limited, Queen's University
    Inventors: Vasanta Chivukula, Michael Sayer, David R. McDonald, Ismail T. Emesh
  • Patent number: 6146905
    Abstract: A ferroelectric dielectric for microwave applications is provided comprising a polycrystalline perovskite phase of lead zirconate titanate dielectric material. Small grain size material is provided by a low temperature process, by a rapid thermal annealing process. A layer of amorphous ferroelectric precursor material is deposited and annealed in an oxygen containing atmosphere in the presence of water vapor, preferably with the addition of a few percent of ozone, and at a temperature of less than 500.degree. C. Advantageously, the method provides for formation of a ferroelectric material comprising lead zirconate titanate with a grain size less than 20 nm, with low film stress, high dielectric constant and low leakage current, which has excellent ferroelectric characteristics up to 10 GHz. This material has applications for capacitors, as filters, decoupling, coupling, and bypass elements and also for high frequency surface acoustic wave devices.
    Type: Grant
    Filed: June 17, 1999
    Date of Patent: November 14, 2000
    Assignee: Nortell Networks Limited
    Inventors: Vasanta Chivukula, Pak K. Leung
  • Patent number: 6077715
    Abstract: A ferroelectric dielectric for microwave applications is provided comprising a polycrystalline perovskite phase of lead zirconate titanate dielectric material. Small grain size material is provided by a low temperature process, by a rapid thermal annealing process. A layer of amorphous ferroelectric precursor material is deposited and annealed in an oxygen containing atmosphere in the presence of water vapour, preferably with the addition of a few percent of ozone, and at a temperature of less than 500.degree. C. Advantageously, the method provides for formation of a ferroelectric material comprising lead zirconate titanate with a grain size less than 20 nm, with low film stress, high dielectric constant and low leakage current, which has excellent ferroelectric characteristics up to 10 GHz. This material has applications for capacitors, as filters, decoupling, coupling, and bypass elements and also for high frequency surface acoustic wave devices.
    Type: Grant
    Filed: December 12, 1996
    Date of Patent: June 20, 2000
    Assignee: Nortel Networks Corporation
    Inventors: Vasanta Chivukula, Pak K. Leung
  • Patent number: 6066581
    Abstract: A sol-gel precursor mixture for forming a perovskite ferroelectric material and a method for forming a ferroelectric material are provided. The precursor solution comprises a sol-gel formulation of a mixture of an inorganic salt of at least one metal, and metal-organic compounds of other constituent metals in a suitable pH controlled aqueous solvent mixture to form a stable, clear sol-gel mixture. The precursor solution and method provides for formation of thin layers of other ferroelectric dielectrics and piezoelectric materials, particularly lead containing materials, for application including non-volatile DRAMs, optoelectronic devices relying on non-linear optical properties, and piezoelectric devices, and is compatible with processing for submicron device structures for bipolar, CMOS or bipolar CMOS circuits.
    Type: Grant
    Filed: July 25, 1996
    Date of Patent: May 23, 2000
    Assignees: Nortel Networks Corporation, Queen's University
    Inventors: Vasanta Chivukula, Michael Sayer, David R. McDonald, Ismail T. Emesh
  • Patent number: 5886867
    Abstract: A ferroelectric dielectric for microwave applications is provided including a polycrystalline perovskite phase of lead zirconate titanate dielectric material. Small grain size material is provided by a low temperature process, by a rapid thermal annealing process. A layer of amorphous ferroelectric precursor material is deposited and annealed in an oxygen containing atmosphere in the presence of water vapour, preferably with the addition of a few percent of ozone, and at a temperature of less than 500.degree. C. Advantageously, the method provides for formation of a ferroelectric material including lead zirconate titanate with a grain size less than 20 nm, with low film stress, high dielectric constant and low leakage current, which has excellent ferroelectric characteristics up to 10 GHz. This material has applications for capacitors, as filters, decoupling, coupling, and bypass elements and also for high frequency surface acoustic wave devices.
    Type: Grant
    Filed: March 10, 1997
    Date of Patent: March 23, 1999
    Assignee: Northern Telecom Limited
    Inventors: Vasanta Chivukula, Pak K. Leung
  • Patent number: 5789268
    Abstract: An improved electrode structure compatible with ferroelectric capacitor dielectrics is provided. In particular, a multilayer electrode having improved adhesion to ferroelectric materials such as PZT is formed comprising a first layer of a noble metal, a second layer of another metal and a thicker layer of the noble metal, which are annealed to cause controlled interdiffusion of the layers forming a mixed metal surface layer having a rough interface with the dielectric layer. For example, the first two layers comprise relatively thin .about.200 .ANG. layers of Pt and Ti, and then a thicker layer of the main, first, electrode material is deposited on top. Non-uniform interdiffusion of the layers during annealing causes intermixing of the Pt and Ti layers at the interfaces forming a Pt/Ti alloy having a rough surface. The rough surface, and particularly hillocks formed at the interface, penetrate into the ferroelectric films, and anchor the electrode material to the dielectric.
    Type: Grant
    Filed: October 10, 1996
    Date of Patent: August 4, 1998
    Assignee: Northern Telecom Limited
    Inventors: Vasanta Chivukula, Pak K. Leung
  • Patent number: 5753945
    Abstract: An integrated circuit structure including dielectric barrier layer compatible with perovskite ferroelectric materials and comprising zirconium titanium oxide, ZrTiO.sub.4, and a method of formation of the dielectric barrier layer by sol gel process is described. The amorphous, mixed oxide barrier layer has excellent dielectric properties up to GHz frequencies, and crystallizes above 800.degree. C., facilitating device processing. In particular, the barrier layer is compatible with lead containing perovskites, including PZT and PLZT ferroelectric dielectrics for example for application in non-volatile memory cells, and high value capacitors for integrated circuits, using silicon or GaAs integrated circuit technologies.
    Type: Grant
    Filed: February 1, 1996
    Date of Patent: May 19, 1998
    Assignee: Northern Telecom Limited
    Inventors: Vasanta Chivukula, Pak K. Leung
  • Patent number: 5612560
    Abstract: An improved electrode structure compatible with ferroelectric capacitor dielectrics is provided. In particular, a multilayer electrode having improved adhesion to ferroelectric materials such as PZT is formed comprising a first layer of a noble metal, a second layer of another metal and a thicker layer of the noble metal, which are annealed to cause controlled interdiffusion of the layers forming a mixed metal surface layer having a rough interface with the dielectric layer. For example, the first two layers comprise relatively thin .about.200.ANG. layers of Pt and Ti, and then a thicker layer of the main, first, electrode material is deposited on top. Non- uniform interdiffusion of the layers during annealing causes intermixing of the Pt and Ti layers at the interfaces forming a Pt/Ti alloy having a rough surface. The rough surface, and particularly hillocks formed at the interface, penetrate into the ferroelectric films, and anchor the electrode material to the dielectric.
    Type: Grant
    Filed: October 31, 1995
    Date of Patent: March 18, 1997
    Assignee: Northern Telecom Limited
    Inventors: Vasanta Chivukula, Pak K. Leung