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).
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Patent number: 8787340Abstract: 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: GrantFiled: February 2, 2012Date of Patent: July 22, 2014Assignee: Ericsson ABInventors: Xixian Chen, Vasanta Chivukula, Weigang Li, Guoqiang Xue, Ryan Santa, Miroslav Budic, Brian Troup, Martin Kendall
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Patent number: 8699415Abstract: 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: GrantFiled: May 2, 2011Date of Patent: April 15, 2014Assignee: Apple Inc.Inventors: Xixian Chen, Weigang Li, Vasanta Chivukula, Shiva Mirzaei-Rezaei, Brian Troup, Miroslav Budic, Yong Zhou, Ryan Santa
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Publication number: 20120127943Abstract: 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: ApplicationFiled: February 2, 2012Publication date: May 24, 2012Applicant: ERICSSON ABInventors: Xixian Chen, Vasanta Chivukula, Weigang Li, Guoqiang Xue, Ryan Santa, Miroslav Budic, Brian Troup, Martin Kendall
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Patent number: 8134963Abstract: 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: GrantFiled: April 4, 2008Date of Patent: March 13, 2012Assignee: Ericsson ABInventors: Xixian Chen, Vasanta Chivukula, Weigang Li, Guoqiang Xue, Ryan Santa, Miroslav Budic, Brian Troup, Martin Kendall
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Publication number: 20110206007Abstract: 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: ApplicationFiled: May 2, 2011Publication date: August 25, 2011Applicant: NORTEL NETWORKS LIMITEDInventors: Xixian Chen, Weigang Li, Vasanta Chivukula, Shiva Mirzaei-Rezaei, Brian Troup, Miroslav Budic, Yong Zhou, Ryan Santa
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Patent number: 7936720Abstract: 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: GrantFiled: April 28, 2006Date of Patent: May 3, 2011Assignee: Nortel Networks LimitedInventors: Xixian Chen, Weigang Li, Vasanta Chivukula, Shiva Mirzaei-Rezaei, Brian Troup, Miroslav Budic, Yong Zhou, Ryan Santa
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Publication number: 20060245407Abstract: 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: ApplicationFiled: April 28, 2006Publication date: November 2, 2006Applicant: NORTEL NETWORKS LIMITEDInventors: Xixian Chen, Weigang Li, Vasanta Chivukula, Shiva Mirzaei-Rezaei, Brian Troup, Miroslav Budic, Yong Zhou, Ryan Santa
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Patent number: 6337032Abstract: 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: GrantFiled: February 16, 2000Date of Patent: January 8, 2002Assignees: Nortel Networks Limited, Queen's UniversityInventors: Vasanta Chivukula, Michael Sayer, David R. McDonald, Ismail T. Emesh
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Patent number: 6146905Abstract: 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: GrantFiled: June 17, 1999Date of Patent: November 14, 2000Assignee: Nortell Networks LimitedInventors: Vasanta Chivukula, Pak K. Leung
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Patent number: 6077715Abstract: 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: GrantFiled: December 12, 1996Date of Patent: June 20, 2000Assignee: Nortel Networks CorporationInventors: Vasanta Chivukula, Pak K. Leung
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Patent number: 6066581Abstract: 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: GrantFiled: July 25, 1996Date of Patent: May 23, 2000Assignees: Nortel Networks Corporation, Queen's UniversityInventors: Vasanta Chivukula, Michael Sayer, David R. McDonald, Ismail T. Emesh
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Patent number: 5886867Abstract: 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: GrantFiled: March 10, 1997Date of Patent: March 23, 1999Assignee: Northern Telecom LimitedInventors: Vasanta Chivukula, Pak K. Leung
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Patent number: 5789268Abstract: 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: GrantFiled: October 10, 1996Date of Patent: August 4, 1998Assignee: Northern Telecom LimitedInventors: Vasanta Chivukula, Pak K. Leung
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Patent number: 5753945Abstract: 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: GrantFiled: February 1, 1996Date of Patent: May 19, 1998Assignee: Northern Telecom LimitedInventors: Vasanta Chivukula, Pak K. Leung
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Patent number: 5612560Abstract: 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: GrantFiled: October 31, 1995Date of Patent: March 18, 1997Assignee: Northern Telecom LimitedInventors: Vasanta Chivukula, Pak K. Leung