Patents by Inventor Zhu Ji

Zhu Ji 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: 9712306
    Abstract: A wireless communication system is presented in which subframe-specific link adaptation is performed. A mobile device can transmit a signal that informs a base station whether a particular subframe was received successfully. Additionally the mobile device can calculate channel state information (CSI) for a subframe and report the CSI to a base station. The reported CSI may or may not include an indicator for informing the base station about from which type of subframe the CSI was derived. The base station can receive the signal, the CSI and/or the indicator. Based on what information the base station has received, it performs subframe-specific BLER filtering and subframe-specific link adaptation scheduling and MCS adjustments.
    Type: Grant
    Filed: January 16, 2014
    Date of Patent: July 18, 2017
    Assignee: Apple Inc.
    Inventors: Zhu Ji, Johnson O. Sebeni, Navid Damji
  • Patent number: 9686750
    Abstract: Methods and apparatus for adaptively adjusting temporal parameters such as e.g., wake-up times of digital tracking algorithms (such as timing, frequency and power control). In one exemplary embodiment, wake-up times for tracking loops are based on success/error metrics (e.g., Block Error Rate (BLER), Bit Error Rate (BER), Packet Error Rate (PER), Cyclic Redundancy Checks (CRC), etc.) of one or more previous discontinuous reception (DRX) cycles. In a second embodiment, wake-up times for tracking loops are based on residual frequency and timing errors, etc.
    Type: Grant
    Filed: September 20, 2012
    Date of Patent: June 20, 2017
    Assignee: Apple Inc.
    Inventors: Zhu Ji, Jason Shi, Johnson Sebini, Navid Damji, Li Su
  • Patent number: 9660838
    Abstract: A method to be performed at a station configured to connect to a Long Term Evolution radio access network (LTE-RAN) to utilize enhanced Multimedia Broadcast Multicast Services using a Multicast-Broadcast Single-Frequency Network (MBSFN). The method including receiving a MBSFN subframe having a MBSFN subframe structure including a plurality of Orthogonal Frequency-Division Multiplexing (OFDM) symbols, a first one of the OFDM symbols having a first reference symbol inserted therein, a second one of the OFDM symbols having a second reference symbol inserted therein, determining a rate of change of channel conditions being experienced by the station and performing a non-destaggered channel estimation when the rate of change of channel conditions is greater than a predetermined threshold, the non-destaggered channel estimation using a first Channel Impulse Response (CIR) at the first OFDM symbol and a second CIR at the second OFDM symbol.
    Type: Grant
    Filed: May 29, 2014
    Date of Patent: May 23, 2017
    Assignee: APPLE INC.
    Inventors: Zhu Ji, Johnson O. Sebeni, Navid Damji
  • Patent number: 9596633
    Abstract: Adaptive neighboring cell measurement scaling by a wireless user equipment (UE) device. The UE may operate alternately in active and inactive states in a periodic manner according to DRX cycle timing for each of a plurality of DRX cycles. Paging messages may be checked for while in the active state during each DRX cycle. If a paging message is received, it may be decoded using a joint detection technique. The UE may adaptively determine whether or not to perform neighboring cell measurements during at least a subset of the DRX cycles, and perform neighboring cell measurements according to the adaptive determination. The adaptive determination may be based on one or more of joint detection of paging messages, one or more previous cell measurements, or an amount of motion of the UE.
    Type: Grant
    Filed: December 20, 2013
    Date of Patent: March 14, 2017
    Assignee: Apple Inc.
    Inventors: Zhu Ji, Johnson O. Sebeni, Xiantao Sun, Yu-Lin Wang
  • Patent number: 9577846
    Abstract: Apparatus and methods for channel estimation in a Multimedia Broadcast Multicast Service (MBMS) Single Frequency Network (MBSFN) are disclosed. A representative method includes a wireless communication device receiving multiple frames, each frame including multiple subframes, each subframe including multiple symbols. The wireless communication device determines whether subframes include MBMS data or not. For subframes that include MBMS data, the wireless communication device excludes all or certain symbols of the subframes that include MBMS data from a channel estimation process. The wireless communication device determines whether the subframes include MBMS data based at least in part on a channel impulse response and/or a channel energy response for one or more symbols of the subframes.
    Type: Grant
    Filed: February 28, 2014
    Date of Patent: February 21, 2017
    Assignee: Apple Inc.
    Inventors: Navid Damji, Zhu Ji, Johnson O. Sebeni, Gaurav Nukala, Srinivasan Vasudevan
  • Patent number: 9572062
    Abstract: Methods and apparatus for managing radio measurements during discontinuous reception. In one exemplary embodiment, the distribution of Long Term Evolution (LTE) DRX measurements is staggered or distributed across multiple DRX cycles (which may be contiguous or non-contiguous) so as to reduce the transceiver activity and power consumption. The exemplary UE in one implementation only performs a subset of measurements during each DRX cycle. By staggering or distributing cell measurements over multiple DRX cycles, the UE can improve power consumption, while still conforming to measurement requirements.
    Type: Grant
    Filed: June 8, 2015
    Date of Patent: February 14, 2017
    Assignee: Apple Inc.
    Inventors: Zhu Ji, Jason Shi, Johnson Sebeni, Navid Damji, Li Su
  • Patent number: 9509544
    Abstract: Methods and apparatuses to determine a frequency adjustment in a mobile wireless device are disclosed. A method includes determining a coarse frequency error estimate and multiple fine frequency error estimates; selecting at least one candidate fine frequency error estimate having a frequency value closest to a corresponding frequency value for the coarse frequency error estimate; and determining a frequency adjustment based on a combination of the coarse frequency error estimate and the selected at least one candidate fine frequency error estimate. In an embodiment, the method further includes calculating a confidence metric for the coarse frequency error estimate; when the confidence metric exceeds a threshold value, determining the frequency adjustment based on the candidate fine frequency error estimate; otherwise, determining the frequency adjustment based on a fine frequency error estimate in the plurality of fine frequency error estimates closest to a most recent previous fine frequency error estimate.
    Type: Grant
    Filed: January 14, 2016
    Date of Patent: November 29, 2016
    Assignee: Apple Inc.
    Inventors: Zhu Ji, Johnson O. Sebeni, Yu-Lin Wang
  • Patent number: 9500628
    Abstract: Providing adaptive channel state feedback (CSF) reports in discontinuous reception (DRX) scenarios in a power-efficient manner. The described algorithm may be able to make adaptive decisions to carry over the CSF from previous DRX cycles based on channel conditions, DRX cycle length, and/or the requirements of CSF reporting for current DRX cycle. The proposed approach can allow for more efficient power consumption related to CSF reports in DRX scenarios where new CSF reports have little or no impact to throughput.
    Type: Grant
    Filed: September 12, 2014
    Date of Patent: November 22, 2016
    Assignee: Apple Inc.
    Inventors: Zhu Ji, Navid Damji, Johnson O. Sebeni
  • Publication number: 20160323930
    Abstract: Methods and apparatus to reduce power consumption in user equipment (UE) that operates in a connected discontinuous reception (C-DRX) mode while in communication with wireless network are disclosed. A C-DRX warm-up period before the UE enters an on-duration is adjusted dynamically based on one or more factors including a time division duplex (TDD) uplink/downlink (UL/DL) subframe configuration, signal-to-noise ratio (SNR) values, and Doppler shift values. The C-DRX warm-up period is adapted based on the pattern of DL subframes in the UL/DL subframe configuration by including DL subframes that best contribute to channel estimation and adaptive tracking loops based on measured SNR and Doppler shift conditions. Favorable channel conditions, such as higher SNR and lower Doppler shift, can require fewer DL subframes and consequently shorter C-DRX warm-up periods. Higher Doppler shift values indicate more rapidly varying channel conditions and require DL subframes positioned closer to the start of the on-duration.
    Type: Application
    Filed: March 28, 2016
    Publication date: November 3, 2016
    Inventors: Zhu JI, Johnson O. SEBENI, Tahir SHAMIM
  • Publication number: 20160286535
    Abstract: A user equipment and method performs an adaptive channel estimation. The method performed at a user equipment includes receiving physical downlink control channel (PDCCH) information for a subframe from a network, the subframe including reference symbols at predetermined times therein. If the PDCCH information does not include a downlink grant for the user equipment, a measured value of a network metric experienced by the user equipment is determined and compared to a threshold criteria. A first set of the reference symbols is used for channel estimation when the threshold value is satisfied and a second set of the reference symbols is used for channel estimation when the threshold is not satisfied, the first set of references symbols is a subset of the second set of the reference symbols. In another embodiment, a previously determined channel estimation at a previous subframe is used for the subframe when the threshold is satisfied.
    Type: Application
    Filed: September 4, 2015
    Publication date: September 29, 2016
    Inventors: Zhu JI, Johnson O. SEBENI, Yu-Lin WANG
  • Patent number: 9426672
    Abstract: Methods and apparatus for network-based detection and mitigation of hybrid client device reception outage events. For example, in one embodiment, a cellular device uses a single-radio solution to support circuit-switched calls on a CDMA 1X network and packet-switched calls on LTE. Periodically, the cellular device tunes away from LTE and monitors CDMA 1X activity, and vice versa. During these tuned-away periods, the network adjusts operation to mitigate adverse effects (e.g., underutilization of radio resources, synchronization loss, etc.).
    Type: Grant
    Filed: March 26, 2013
    Date of Patent: August 23, 2016
    Assignee: Apple Inc.
    Inventors: Jianxiong Shi, Johnson O. Sebeni, Li Su, Navid Damji, Paul V. Flynn, Sarma V. Vangala, Sreevalsan Vallath, Thanigaivelu Elangovan, Zhu Ji
  • Patent number: 9420523
    Abstract: Methods and apparatuses to reduce a time to scan one or more frequency channel bands by a wireless communication device are disclosed. The methods include performing, at the wireless communication device, a power scan of a band of radio frequencies; determining a maximum power level for a frequency channel in the band of radio frequencies found by the power scan; comparing the maximum power level to a threshold power level; in an instance in which the maximum power level does not equal or exceed the threshold power level, attempting acquisition on a first number of frequency channels; and in an instance in which the maximum power equals or exceeds the threshold power level, attempting acquisition on a second number of frequency channels. The second number of frequency channels is greater than the first number of frequency channels.
    Type: Grant
    Filed: November 22, 2013
    Date of Patent: August 16, 2016
    Assignee: Apple Inc.
    Inventors: Navid Damji, Sree Ram Kodali, Johnson O. Sebeni, Zhu Ji
  • Patent number: 9414315
    Abstract: A method for reducing power consumption in connected mode discontinuous reception is disclosed. The method can include a wireless communication device sending a transmission for a pending HARQ retransmission process and receiving an ACK for the transmission. The method can further include the wireless communication device determining a subset of remaining uplink transmission opportunities in the pending HARQ retransmission process to monitor for an uplink grant in response to receiving the ACK and monitoring the subset of remaining uplink transmission opportunities for an uplink grant.
    Type: Grant
    Filed: February 5, 2014
    Date of Patent: August 9, 2016
    Assignee: Apple Inc.
    Inventors: Navid Damji, Giri Prassad Deivasigamani, Johnson O. Sebeni, Luciano M. Verger, Madhusudan Chaudhary, Samy Khay-Ibbat, Sarma V. Vangala, Shivesh Makharia, Sree Ram Kodali, Srinivasan Vasudevan, Thanigaivelu Elangovan, Zhu Ji
  • Patent number: 9380535
    Abstract: Methods and apparatus for adaptively adjusting receiver operation during non-continuous (e.g., discontinuous) reception. In one exemplary embodiment, a user device such as a User Equipment (UE) adaptively adjusts its reception mode based on a determined actual error. The reception mode is selected so as to improve reception performance, while still minimizing overall power consumption.
    Type: Grant
    Filed: December 15, 2015
    Date of Patent: June 28, 2016
    Assignee: Apple Inc.
    Inventors: Johnson Sebeni, Jason Shi, Zhu Ji, Navid Damji, Li Su
  • Patent number: 9374191
    Abstract: Outer loop link adaptation for device resumption. A user equipment (UE) and base station (BS) may be in communication in a first network (e.g., an LTE network). Communication between the UE and the BS may be interrupted, e.g., due to a long fading environment, the UE tuning away to a second network (e.g., a CDMA network). Accordingly, the measured error rate may increase dramatically. After resumption from the interruption, a negative offset may be applied to a reported SINR value from the UE due to the previous increase in error rate. Upon improvement in the error rate, a larger, positive offset adjustment may be added to the negative offset, allowing the estimated SINR to return to reported SINR more quickly. Additionally, the error rate estimation may be adjusted to converge to a more recently measured more quickly by decreasing a feedback filter coefficient.
    Type: Grant
    Filed: September 7, 2012
    Date of Patent: June 21, 2016
    Assignee: Apple Inc.
    Inventors: Tarik Tabet, Paul V. Flynn, Syed A. Mujtaba, Navid Damji, Zhu Ji, Sreevalsan Vallath
  • Publication number: 20160134457
    Abstract: Methods and apparatuses to determine a frequency adjustment in a mobile wireless device are disclosed. A method includes determining a coarse frequency error estimate and multiple fine frequency error estimates; selecting at least one candidate fine frequency error estimate having a frequency value closest to a corresponding frequency value for the coarse frequency error estimate; and determining a frequency adjustment based on a combination of the coarse frequency error estimate and the selected at least one candidate fine frequency error estimate. In an embodiment, the method further includes calculating a confidence metric for the coarse frequency error estimate; when the confidence metric exceeds a threshold value, determining the frequency adjustment based on the candidate fine frequency error estimate; otherwise, determining the frequency adjustment based on a fine frequency error estimate in the plurality of fine frequency error estimates closest to a most recent previous fine frequency error estimate.
    Type: Application
    Filed: January 14, 2016
    Publication date: May 12, 2016
    Inventors: Zhu JI, Johnson O. SEBENI, Yu-Lin WANG
  • Patent number: 9332584
    Abstract: Connected-mode discontinuous reception (C-DRX) cycle scaling by a wireless user equipment (UE) device. The UE may establish a connection with a network via a wireless link, which may operate according to LTE. The UE may communicate with the network via the wireless link using C-DRX over a plurality of C-DRX cycles. Each C-DRX cycle may include a period of time during which the UE operates in a reduced-power state and a scheduled on-duration period of time. An indication may be received to remain in the reduced-power state during the scheduled on-duration period of time of at least one C-DRX cycle. The UE may remain in the reduced-power state during the scheduled on-duration period of time of at least one C-DRX cycle in response to the indication.
    Type: Grant
    Filed: October 18, 2012
    Date of Patent: May 3, 2016
    Assignee: Apple Inc.
    Inventors: Luciano M Verger, Navid Damji, Zhu Ji
  • Publication number: 20160100366
    Abstract: Methods and apparatus for adaptively adjusting receiver operation during non-continuous (e.g., discontinuous) reception. In one exemplary embodiment, a user device such as a User Equipment (UE) adaptively adjusts its reception mode based on a determined actual error. The reception mode is selected so as to improve reception performance, while still minimizing overall power consumption.
    Type: Application
    Filed: December 15, 2015
    Publication date: April 7, 2016
    Inventors: Johnson Sebeni, Jason Shi, Zhu Ji, Navid Damji, Li Su
  • Patent number: 9301257
    Abstract: Methods and apparatus to reduce power consumption in user equipment (UE) that operates in a connected discontinuous reception (C-DRX) mode while in communication with wireless network are disclosed. A C-DRX warm-up period before the UE enters an on-duration is adjusted dynamically based on one or more factors including a time division duplex (TDD) uplink/downlink (UL/DL) subframe configuration, signal-to-noise ratio (SNR) values, and Doppler shift values. The C-DRX warm-up period is adapted based on the pattern of DL subframes in the UL/DL subframe configuration by including DL subframes that best contribute to channel estimation and adaptive tracking loops based on measured SNR and Doppler shift conditions. Favorable channel conditions, such as higher SNR and lower Doppler shift, can require fewer DL subframes and consequently shorter C-DRX warm-up periods. Higher Doppler shift values indicate more rapidly varying channel conditions and require DL subframes positioned closer to the start of the on-duration.
    Type: Grant
    Filed: May 15, 2014
    Date of Patent: March 29, 2016
    Assignee: Apple Inc.
    Inventors: Zhu Ji, Johnson O. Sebeni, Tahir Shamim
  • Patent number: 9295063
    Abstract: Adaptive generation of channel state feedback (CSF) based on base station CSF scheduling. CSF report scheduling information may be received. CSF metrics may be generated based at least in part on the CSF report scheduling information. A CSF report including the CSF metrics may be transmitted to the base station. Periodicity of CSF report scheduling or other CSF report scheduling factors may be taken into consideration in generation of the CSF metrics.
    Type: Grant
    Filed: June 29, 2015
    Date of Patent: March 22, 2016
    Assignee: Apple Inc.
    Inventors: Zhu Ji, Navid Damji, Johnson O. Sebeni