Patents by Inventor Ahmadreza Hedayat

Ahmadreza Hedayat 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: 8971273
    Abstract: Dynamic bandwidth selection techniques are provided for a plurality of wireless access point devices that operate in a wireless local area network. Each access point device is capable of serving wireless client devices with a bandwidth from a set of possible bandwidths associated with one or multiple contiguous or non-contiguous radio frequency channels. A bias is generated based on determined type of traffic or client composition for each access point device, the bias favoring a channel assignment that results in a particular bandwidth in the set of bandwidths. The bias is applied to metrics representing severity and degree of interference for each channel to generate adjusted metrics. A bandwidth from the set of possible bandwidths is selected for each access point device based on the adjusted metrics.
    Type: Grant
    Filed: October 9, 2012
    Date of Patent: March 3, 2015
    Assignee: Cisco Technology, Inc.
    Inventors: Douglas Chan, Mansoor Ahmed, Ahmadreza Hedayat, Brian D. Hart
  • Publication number: 20150016435
    Abstract: Techniques are presented herein for providing hybrid contention mechanisms for a wireless medium. A first wireless device (e.g., a wireless access point) that serves a plurality of second wireless devices (e.g., client devices) in a wireless network, groups the plurality of second wireless devices into sets based on commonality of the second wireless devices in terms of one or more of: power requirements and throughput requirements. A time interval on a wireless channel during which the second wireless devices may contend for usage of the wireless medium is partitioned into a plurality of disjoint or overlapping contention periods. Each set of second wireless devices is assigned to a corresponding one of the plurality of contention periods such that only second wireless devices in each set contend for access to the wireless channel during the corresponding contention period assigned to that set.
    Type: Application
    Filed: September 12, 2013
    Publication date: January 15, 2015
    Applicant: Cisco Technology, Inc.
    Inventor: Ahmadreza Hedayat
  • Patent number: 8908783
    Abstract: Techniques are provided for receiving uplink transmissions at a plurality of antennas at a base station from a plurality of client stations. Uplink spatial transmissions are analyzed to produce a plurality of direction of arrival (DOA) components associated with the plurality of client stations. The DOA components associated with the plurality of client stations are compared with each other and two or more client stations are selected to participate in an uplink collaborative spatial multiplexing transmission session based on dissimilarities of their DOA components.
    Type: Grant
    Filed: October 21, 2009
    Date of Patent: December 9, 2014
    Assignee: Cisco Technology, Inc.
    Inventors: Ahmadreza Hedayat, Hang Jin
  • Patent number: 8873384
    Abstract: Disclosed in an example embodiment is an apparatus comprising a transmitter and processing logic coupled with the transmitter. The processing logic is configured to send data via the transmitter. The processing logic generates a request to send frame. The processing logic encodes data representative of a bandwidth parameter set in the request to send frame. The processing logic transmits the request to send frame via the transmitter.
    Type: Grant
    Filed: November 1, 2010
    Date of Patent: October 28, 2014
    Assignee: Cisco Technology, Inc.
    Inventors: Brian Hart, Ahmadreza Hedayat
  • Patent number: 8842753
    Abstract: Techniques are provided for generating an estimate of the phase and magnitude imbalance of a receiver in a communication device. For each of a plurality of symbols in a signal received by the communication device, a plurality of tones that make up the symbol are obtained. For each of the plurality of symbols, each tone is multiplied by its respective mirror tone to produce a plurality of mirror tone multiplication results, and the plurality of the mirror tone multiplication results are summed over tones to produce a sum of multiplication results for each symbol. The total power of all tones for each symbol is obtained to produce a tone power quantity for each symbol. The estimate of the phase and magnitude imbalance in the received signal is generated based on the sum of the multiplication results for each of the plurality of symbols and the tone power quantity for each of the plurality of symbols.
    Type: Grant
    Filed: June 27, 2011
    Date of Patent: September 23, 2014
    Assignee: Cisco Technology, Inc.
    Inventors: Mohammad Janani, Ahmadreza Hedayat
  • Patent number: 8797881
    Abstract: In accordance with an example embodiment, there is disclosed herein a coexistence mechanism for multiple channels. A plurality of channels are monitored to determine which channels are available for communications. Upon receiving a request to establish communications on a channel set within the plurality of channels, a response is sent to the request on at least one in the channel set. The response comprises data representative of which channels from the channel set are available for communications. Optionally, the response may include data indicating how long the unavailable channels will be occupied.
    Type: Grant
    Filed: June 13, 2011
    Date of Patent: August 5, 2014
    Assignee: Cisco Technology, Inc.
    Inventors: Brian Donald Hart, Raghuram Rangarajan, Ahmadreza Hedayat
  • Patent number: 8718172
    Abstract: Techniques are provided for generating a precoding matrix for a multi-user multiple-input multiple-output wireless communication system. A first wireless communication device is provided that has a plurality of antennas from which multiple spatial streams are to be simultaneously transmitted to a plurality of second wireless communication devices. A channel matrix is computed between the antennas of the first device and the antennas of each of the second wireless communication devices to produce a plurality of client-specific channel matrices. A singular value decomposition is computed of each client-specific channel matrices. A number of strongest singular values and their corresponding singular vectors are stored from the singular decomposition of each of the client-specific channel matrices. From each client-specific channel matrix, a principal component-like single-client channel matrix is computed.
    Type: Grant
    Filed: April 30, 2012
    Date of Patent: May 6, 2014
    Assignee: Cisco Technology, Inc.
    Inventors: Brian Donald Hart, Genyuan Wang, Ahmadreza Hedayat, Paul J. Stager
  • Publication number: 20140098748
    Abstract: Dynamic bandwidth selection techniques are provided for a plurality of wireless access point devices that operate in a wireless local area network. Each access point device is capable of serving wireless client devices with a bandwidth from a set of possible bandwidths associated with one or multiple contiguous or non-contiguous radio frequency channels. A bias is generated based on determined type of traffic or client composition for each access point device, the bias favoring a channel assignment that results in a particular bandwidth in the set of bandwidths. The bias is applied to metrics representing severity and degree of interference for each channel to generate adjusted metrics. A bandwidth from the set of possible bandwidths is selected for each access point device based on the adjusted metrics.
    Type: Application
    Filed: October 9, 2012
    Publication date: April 10, 2014
    Applicant: CISCO TECHNOLOGY, INC.
    Inventors: Douglas Chan, Mansoor Ahmed, Ahmadreza Hedayat, Brian D. Hart
  • Publication number: 20140050156
    Abstract: Techniques are provided for selecting channels for use by access points operating in a wireless local area network. Metrics are computed for at least one set of radio frequency (RF) channels, wherein the set of RF channels comprises at least two RF channels in a frequency band that are available for use by a wireless network for a wider bandwidth mode that combines bandwidth of two or more RF channels. Alignment of individual primary and secondary RF channels is determined in the set of RF channels for operation of at least first and second wireless networks. A bias is applied to the metrics for each RF channel that is a member of the set of RF channels for the primary channel depending on alignment of the primary and secondary channels of the respective first and second wireless networks to produce adjusted metrics, based on which RF channels are assigned.
    Type: Application
    Filed: August 14, 2012
    Publication date: February 20, 2014
    Applicant: CISCO TECHNOLOGY, INC.
    Inventors: Douglas Chan, Mansoor Ahmed, Ahmadreza Hedayat, Brian D. Hart
  • Patent number: 8638834
    Abstract: Energy in a frequency band is received at a wireless communication device and data is generated representing samples of a received time domain waveform from the received energy. Data for groups of samples of the received time domain waveform is processed to transform the data for the received time domain waveform to produce data for an intermediate domain signal that is in neither the time domain nor the frequency domain. The data representing the intermediate domain signal is analyzed to determine whether a sequence having a predetermined pattern from a set of possible sequences is present in the received energy, and ultimately to determine a sequence of the predetermined pattern whose presence is detected in the received energy.
    Type: Grant
    Filed: July 15, 2009
    Date of Patent: January 28, 2014
    Assignee: Cisco Technology, Inc.
    Inventors: Ahmadreza Hedayat, Mohammad Janani, Hang Jin
  • Patent number: 8599735
    Abstract: Techniques are provided to enable group addressing for multicast transmissions in a frame that is configured to support multi-user transmissions. The frame comprises a header field that is configured to indicate to recipient devices associated with a multi-user transmission interval during which time, frequency and spatial channel resources are allocated to allow for the transmission of a data frame or simultaneous transmission of corresponding ones of a plurality of data frames to respective recipient devices. In the header field, group identification information is wirelessly transmitted that indicates a group of recipient devices which are to receive a transmission during the multi-user transmission interval.
    Type: Grant
    Filed: September 14, 2011
    Date of Patent: December 3, 2013
    Assignee: Cisco Technology, Inc.
    Inventors: Ahmadreza Hedayat, Brian D. Hart
  • Publication number: 20130287131
    Abstract: Techniques are provided for generating a precoding matrix for a multi-user multiple-input multiple-output wireless communication system. A first wireless communication device is provided that has a plurality of antennas from which multiple spatial streams are to be simultaneously transmitted to a plurality of second wireless communication devices. A channel matrix is computed between the antennas of the first device and the antennas of each of the second wireless communication devices to produce a plurality of client-specific channel matrices. A singular value decomposition is computed of each client-specific channel matrices. A number of strongest singular values and their corresponding singular vectors are stored from the singular decomposition of each of the client-specific channel matrices. From each client-specific channel matrix, a principal component-like single-client channel matrix is computed.
    Type: Application
    Filed: April 30, 2012
    Publication date: October 31, 2013
    Applicant: CISCO TECHNOLOGY, INC.
    Inventors: Brian Donald Hart, Genyuan Wang, Ahmadreza Hedayat, Paul J. Stager
  • Publication number: 20130286863
    Abstract: Techniques are provided to determine whether or not incident power at a wireless communication device in at least two frequency channels is from the same device. Incident power in frequency channels allocated to a basic service set in a wireless network is received at a plurality of antennas of the wireless communication device. Channel state information is computed for at least two frequency channels allocated to the basic service set. One or more metrics are generated based on the channel state information in the two frequency channels. The one or more metrics are evaluated to characterize an uplink signal bandwidth associated with the two channels to determine whether or not the incident power in the two channels is from the same device.
    Type: Application
    Filed: April 30, 2012
    Publication date: October 31, 2013
    Applicant: CISCO TECHNOLOGY, INC.
    Inventors: Matthew A. Silverman, Paul J. Stager, Brian D. Hart, Mohammad Janani, Ahmadreza Hedayat
  • Patent number: 8494073
    Abstract: Techniques are provided for computing downlink beamforming weights based on the received data at a base station from a mobile station in a MIMO communication system. An uplink transmission is received at a plurality of antennas at a first communication device from a second communication device, where the uplink transmission comprises a plurality of uplink subbands. The uplink spatial signature is estimated for each of the plurality of uplink subbands. The uplink spatial signature is decomposed into a plurality of direction of arrival (DOA) components for each uplink subband using a transform. Data representing multiple propagation paths between the first communication device and the second communication device is computed for each DOA component. A plurality of direction of departure (DOD) components for each of a plurality of downlink subbands is computed based on the data representing the multiple propagation paths.
    Type: Grant
    Filed: July 14, 2009
    Date of Patent: July 23, 2013
    Assignee: Cisco Technology, Inc.
    Inventors: Genyuan Wang, Li Guo, Ahmadreza Hedayat, Hang Jin
  • Patent number: 8451771
    Abstract: Techniques are provided for a multi-user reservation sequence used when transmitting a multi-user transmission in a wireless network. At a wireless access point device configured to operate in a wireless network, a multi-user request-to-send packet is transmitted as part of a multi-user reservation sequence prior to a multi-user transmission from the wireless access point device to a plurality of wireless client devices that are the intended recipients for the multi-user transmission. The multi-user request-to-send packet comprises duration information and address information configured to address at least some of the plurality of wireless client devices. Clear-to-send packets transmitted from two or more of the plurality of wireless client devices in response to the multi-user request-to-send packet are received at the wireless access point device. Each clear-to-send packet comprises identical content.
    Type: Grant
    Filed: December 13, 2010
    Date of Patent: May 28, 2013
    Assignee: Cisco Technology, Inc.
    Inventors: Ahmadreza Hedayat, Brian D. Hart
  • Publication number: 20130128935
    Abstract: Techniques are provided to compute downlink beamforming weights for beamforming multiple spatial streams to a wireless device when that wireless device does not transmit with a maximum number of spatial streams, and thus when the full dimensional knowledge of the wireless channel to that wireless device needs to be implicitly derived. Uplink signals are received at a plurality of antennas of a first wireless device that are transmitted via a plurality of antennas of a second wireless device. The first wireless device derives values at a plurality of subcarriers of the received signals across the plurality of antennas of the first wireless device. Downlink beamforming weights are computed from values of consecutive subcarriers across the plurality of antennas of the first wireless device. The first wireless device applies the downlink beamforming weights at respective subcarriers to a number of spatial streams to be transmitted to the second wireless device.
    Type: Application
    Filed: November 17, 2011
    Publication date: May 23, 2013
    Applicant: CISCO TECHNOLOGY, INC.
    Inventors: Mohammad Janani, Ahmadreza Hedayat, Matthew A. Silverman
  • Publication number: 20130064161
    Abstract: Techniques are provided to enable group addressing for multicast transmissions in a frame that is configured to support multi-user transmissions. The frame comprises a header field that is configured to indicate to recipient devices associated with a multi-user transmission interval during which time, frequency and spatial channel resources are allocated to allow for the transmission of a data frame or simultaneous transmission of corresponding ones of a plurality of data frames to respective recipient devices. In the header field, group identification information is wirelessly transmitted that indicates a group of recipient devices which are to receive a transmission during the multi-user transmission interval.
    Type: Application
    Filed: September 14, 2011
    Publication date: March 14, 2013
    Applicant: CISCO TECHNOLOGY, INC.
    Inventors: Ahmadreza Hedayat, Brian D. Hart
  • Patent number: 8374271
    Abstract: The present invention discloses a method for generating a signal stream in a multiple-input-multiple-output (MIMO) channel of a wireless communications system. The method comprises encoding at least one transmitting message into a first signal sequence, transforming the first signal sequence into a second and a third signal sequence by a first and a second predetermined rule, respectively, coupling the second signal sequence to a first antenna, coupling the third signal sequence to a second antenna, transmitting a signal stream comprising the first and second signal sequences to a mobile station.
    Type: Grant
    Filed: December 13, 2007
    Date of Patent: February 12, 2013
    Assignee: Cisco Technology, Inc.
    Inventors: Ahmadreza Hedayat, Genyuan Wang, Mohammad Janani, Hanqing Lou
  • Publication number: 20120328053
    Abstract: Techniques are provided for generating an estimate of the phase and magnitude imbalance of a receiver in a communication device. For each of a plurality of symbols in a signal received by the communication device, a plurality of tones that make up the symbol are obtained. For each of the plurality of symbols, each tone is multiplied by its respective mirror tone to produce a plurality of mirror tone multiplication results, and the plurality of the mirror tone multiplication results are summed over tones to produce a sum of multiplication results for each symbol. The total power of all tones for each symbol is obtained to produce a tone power quantity for each symbol. The estimate of the phase and magnitude imbalance in the received signal is generated based on the sum of the multiplication results for each of the plurality of symbols and the tone power quantity for each of the plurality of symbols.
    Type: Application
    Filed: June 27, 2011
    Publication date: December 27, 2012
    Applicant: Cisco Technology, Inc.
    Inventors: Mohammad Janani, Ahmadreza Hedayat
  • Publication number: 20120314583
    Abstract: In accordance with an example embodiment, there is disclosed herein a coexistence mechanism for multiple channels. A plurality of channels are monitored to determine which channels are available for communications. Upon receiving a request to establish communications on a channel set within the plurality of channels, a response is sent to the request on at least one in the channel set. The response comprises data representative of which channels from the channel set are available for communications. Optionally, the response may include data indicating how long the unavailable channels will be occupied.
    Type: Application
    Filed: June 13, 2011
    Publication date: December 13, 2012
    Inventors: Brian Donald HART, Raghuram Rangarajan, Ahmadreza Hedayat