Patents by Inventor Chul Roh

Chul Roh 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: 20130051444
    Abstract: A method of generating normalized bit log-likelihood ratio (LLR) values. A signal is received in a frequency band after transmission over a media, wherein the signal includes at least one complex data symbol having a plurality of information bits, and the complex data symbol is transmitted on at least one frequency channel. Initial LLR values are calculated for each of the plurality of information bits based on bit-to-symbol mapping of modulation and noise variance information from the complex data symbol. An average signal to noise ratio (SNR) of the frequency channel is calculated. Each initial LLR value is normalized by dividing by the average SNR to generate a plurality of normalized LLR values. The normalized LLR values may be quantized to provide a finite-bit representation.
    Type: Application
    Filed: August 22, 2012
    Publication date: February 28, 2013
    Applicant: TEXAS INSTRUMENTS INCORPORATED
    Inventor: JUNE CHUL ROH
  • Patent number: 8380433
    Abstract: Embodiments of the invention provide a blending filter based on extended Kalman filter (EKF), which optimally integrates the IMU navigation data with all other satellite measurements tightly-coupled integration filter. This blending filter can be easily implemented with minor modification to the position engine of stand-alone GNSS receiver. Provided is a low-complexity tightly-coupled integration filter for sensor-assisted global navigation satellite system (GNSS) receiver. The inertial measurement unit (IMU) contains inertial sensors such as accelerometer, magnetometer, and/or gyroscopes Embodiments also include method for pedestrian dead reckoning (PDR) data conversion for ease of GNSS/PDR integration. The PDR position data is converted to user velocity measured at the time instances where GNSS position/velocity estimates are available.
    Type: Grant
    Filed: September 28, 2009
    Date of Patent: February 19, 2013
    Assignee: Texas Instruments Incorporated
    Inventors: June Chul Roh, Deric W. Waters, Srinath Hosur, Goutam Dutta
  • Publication number: 20130039446
    Abstract: A method of channel estimation includes receiving a signal after transmission over a media having a plurality of sub-carriers in a frequency band. The signal is preprocessed including performing a fast Fourier transform (FFT) to generate a plurality of frequency-domain samples. Channel estimating is applied to the plurality of frequency-domain samples using (i) least squares (LS) estimation, wherein the LS estimation generates intermediate LS channel estimates for each of the sub-carriers, and (ii) frequency-domain filtering and scaling the intermediate LS channel estimates. The frequency-domain filtering uses a common frequency-domain filter consisting of a single filter coefficient vector having a plurality of frequency-domain filter coefficients to generate refined channel estimates for each of the plurality of sub-carriers.
    Type: Application
    Filed: August 2, 2012
    Publication date: February 14, 2013
    Applicant: TEXAS INSTRUMENTS INCORPORATED
    Inventor: JUNE CHUL ROH
  • Patent number: 8374788
    Abstract: Embodiments of the invention provide methods to calibrate a tightly-coupled integration filter for inertial sensor-assisted GNSS (global navigation satellite system) receiver. The inertial measurement unit (IMU) contains inertial sensors such as accelerometer, magnetometer, and/or gyroscopes. Embodiments include creating a coordinate transformation matrix using a latest position fix (latitude and longitude). Transforming state variables to a local navigation coordinate using coordinate transformation matrix. The state variables of the integration filter which include speed scale-factor and/or heading bias are estimated. A blended calibrated position fix is outputted.
    Type: Grant
    Filed: March 29, 2012
    Date of Patent: February 12, 2013
    Assignee: Texas Instruments Incorporated
    Inventor: June Chul Roh
  • Patent number: 8374214
    Abstract: A method comprises generating, by logic, a random number. The method also comprises determining a next frequency in said sequence using the random number and one or more of a minimum separation, a channel number, and a number of channels. The method further comprises hopping to the next frequency.
    Type: Grant
    Filed: April 13, 2010
    Date of Patent: February 12, 2013
    Assignee: Texas Instruments Incorporated
    Inventors: June Chul Roh, Anuj Batra
  • Patent number: 8306161
    Abstract: A method in accordance with an embodiment of the invention includes producing a first signal match indication based on at least one match indication indicative of a match between at least one signal received in at least one band and a reference signal. The method also includes producing a first signal multipath combined signal based upon the first signal match indication, and detecting a first peak in the first multipath combined signal.
    Type: Grant
    Filed: May 11, 2011
    Date of Patent: November 6, 2012
    Assignee: Texas Instruments Incorporated
    Inventors: June Chul Roh, Anuj Batra, Manoneet Singh, Jaiganesh Balakrishnan
  • Patent number: 8289205
    Abstract: Embodiments of the invention provide a method of reacquiring satellite signals quickly. A pseudorange of at least one satellite is estimated. A user's position is also estimated. Then a signal from at one or more satellites may be received. By detecting when the user is stationary, the Doppler frequency estimation can be corrected or the SNR can be boosted more both of which lead to improved performance. The embodiments allow a GNSS receiver to process signals in when the signal level would otherwise be too low—for example indoors. The embodiments can improve performance when one or more satellites are temporarily blocked but one or more satellites are still being tracked.
    Type: Grant
    Filed: September 7, 2011
    Date of Patent: October 16, 2012
    Assignee: Texas Instruments Incorporated
    Inventors: Deric W. Waters, June Chul Roh, Sandeep Rao
  • Patent number: 8238406
    Abstract: A method consisting of determining, by a symbol mapper, whether a previous burst position is below a threshold, wherein the previous burst position defines a location within a previous symbol. A determination that the previous burst position is below the threshold causes generating, by the symbol mapper, a random number in a complete set, the random number defines a current burst position, the current burst position defines a location within a current symbol and sending or receiving a value in the current burst position. A determination that the previous burst position is above the threshold causes generating, by the symbol mapper, a random number in a reduced set, the random number defines a modified current burst position, the modified current burst position defines a location within the current symbol and sending or receiving a value in the modified current burst position.
    Type: Grant
    Filed: March 25, 2010
    Date of Patent: August 7, 2012
    Assignee: Texas Instruments Incorporated
    Inventors: June Chul Roh, Anuj Batra
  • Publication number: 20120191345
    Abstract: Embodiments of the invention provide methods to calibrate a tightly-coupled integration filter for inertial sensor-assisted GNSS (global navigation satellite system) receiver. The inertial measurement unit (IMU) contains inertial sensors such as accelerometer, magnetometer, and/or gyroscopes. Embodiments include creating a coordinate transformation matrix using a latest position fix (latitude and longitude). Transforming state variables to a local navigation coordinate using coordinate transformation matrix. The state variables of the integration filter which include speed scale-factor and/or heading bias are estimated. A blended calibrated position fix is outputted.
    Type: Application
    Filed: March 29, 2012
    Publication date: July 26, 2012
    Applicant: TEXAS INSTRUMENTS INCORPORATED
    Inventor: June Chul Roh
  • Patent number: 8212720
    Abstract: Embodiments of the invention provide a method of detecting movement to aid GNSS receivers. By detecting when the user is stationary, the Doppler frequency estimation can be corrected or the SNR can be boosted more both of which lead to improved performance. The embodiments allow a GNSS receiver to process signals in when the signal level would otherwise be too low—for example indoors. The embodiments can improve performance when one or more satellites are temporarily blocked but one or more satellites are still being tracked.
    Type: Grant
    Filed: September 24, 2009
    Date of Patent: July 3, 2012
    Assignee: Texas Instruments Incorporated
    Inventors: Deric W. Waters, June Chul Roh, Sandeep Rao
  • Publication number: 20120140858
    Abstract: Systems and methods for fine symbol timing estimation are disclosed herein. In one embodiment, a wireless receiver includes a differential detector, a correlator, a coarse symbol timing estimator, and a fine symbol timing estimator. The differential detector is configured to detect phase differences in a received preamble signal modulated using differential phase shift keying. The correlator is configured to correlate symbol values output by the differential detector against a reference sequence. The coarse symbol timing estimator is configured to generate a coarse symbol timing estimate, and to generate a coarse timing sample symbol index value corresponding to the coarse symbol timing estimate. The fine symbol timing estimator is configured to generate a fine symbol timing estimate that is more accurate than the coarse symbol timing estimate based on the coarse timing sample symbol index value and correlation samples at index values preceding and succeeding the coarse timing sample index value.
    Type: Application
    Filed: December 6, 2010
    Publication date: June 7, 2012
    Applicant: TEXAS INSTRUMENTS INCORPORATED
    Inventors: June Chul ROH, Srinath HOSUR, Timothy M. SCHMIDL
  • Publication number: 20120106609
    Abstract: A system and method for classifying a channel with regard to delay spread in a wireless network applying orthogonal frequency division multiplexing. In one embodiment, a wireless receiver includes a channel classifier. The channel classifier is configured to compute a channel estimate corresponding to a channel traversed by a packet received by the wireless receiver. The channel classifier is also configured to partition the channel estimate into a plurality of windows. Each window corresponds to a range of time of the channel estimate. The channel classifier is further configured to assign a delay spread classification to the channel based on a distribution of energy across the windows.
    Type: Application
    Filed: October 28, 2011
    Publication date: May 3, 2012
    Applicant: TEXAS INSTRUMENTS INCORPORATED
    Inventors: Taejoon KIM, Timothy M. SCHMIDL, Tarkesh PANDE, Anuj BATRA, June Chul ROH
  • Publication number: 20120054584
    Abstract: Apparatus and method for processing a physical layer protocol convergence (PLCP) header. In one embodiment, a wireless device includes a PLCP header processor. The PLCP header processor is configured to: process a physical layer header, process a check value based on the physical layer header, and process an error correction code based on the physical layer header and the check value. A concatenation of the physical layer header, check value, and error correction code the PLCP header processor is configured to process consists of a number of information bits that is an integer multiple of a number of information bits per symbol used to encode the PLCP header.
    Type: Application
    Filed: August 29, 2011
    Publication date: March 1, 2012
    Applicant: TEXAS INSTRUMENTS INCORPORATED
    Inventors: June Chul ROH, Anuj BATRA, Srinath HOSUR
  • Publication number: 20110316738
    Abstract: Embodiments of the invention provide a method of adjusting a bandwidth of receivers. A plurality of outputs from a correlator engine are combined. User dynamics are sensed. Bandwidth of one or more receivers are adjusted. By detecting when the user is stationary, the Doppler frequency estimation can be corrected or the SNR can be boosted more both of which lead to improved performance. The embodiments allow a receiver to process signals in when the signal level would otherwise be too low—for example indoors. The embodiments can improve performance when one or more satellites are temporarily blocked but one or more satellites are still being tracked.
    Type: Application
    Filed: September 7, 2011
    Publication date: December 29, 2011
    Applicant: TEXAS INSTRUMENTS INCORPORATED
    Inventors: Deric W. Waters, June Chul Roh, Sandeep Rao
  • Publication number: 20110316740
    Abstract: Embodiments of the invention provide a method of reacquiring satellite signals quickly. A pseudorange of at least one satellite is estimated. A user's position is also estimated. Then a signal from at one or more satellites may be received. By detecting when the user is stationary, the Doppler frequency estimation can be corrected or the SNR can be boosted more both of which lead to improved performance. The embodiments allow a GNSS receiver to process signals in when the signal level would otherwise be too low—for example indoors. The embodiments can improve performance when one or more satellites are temporarily blocked but one or more satellites are still being tracked.
    Type: Application
    Filed: September 7, 2011
    Publication date: December 29, 2011
    Applicant: TEXAS INSTRUMENTS INCORPORATED
    Inventors: Deric W. Waters, June Chul Roh, Sandeep Rao
  • Patent number: 8054742
    Abstract: A system and method for sidelobe suppression in OFDM communications systems is provided. A method for transmitting an information symbol having a plurality of information sub-carriers and a plurality of active interference cancellation (AIC) sub-carriers includes generating AIC sub-carrier data based on the information to be transmitted, populating the plurality of information sub-carriers with the information, populating the plurality of AIC sub-carriers with the AIC sub-carrier data, applying baseband processing to the information symbol, thereby producing a processed symbol, and transmitting the processed symbol.
    Type: Grant
    Filed: August 26, 2009
    Date of Patent: November 8, 2011
    Assignee: Texas Instruments Incorporated
    Inventors: June Chul Roh, Anuj Batra
  • Publication number: 20110255433
    Abstract: A method in accordance with an embodiment of the invention includes producing a first signal match indication based on at least one match indication indicative of a match between at least one signal received in at least one band and a reference signal. The method also includes producing a first signal multipath combined signal based upon the first signal match indication, and detecting a first peak in the first multipath combined signal.
    Type: Application
    Filed: May 11, 2011
    Publication date: October 20, 2011
    Applicant: TEXAS INSTRUMENTS INCORPORATED
    Inventors: June Chul Roh, Anuj Batra, Manoneet Singh, Jaiganesh Balakrishnan
  • Publication number: 20110255453
    Abstract: A system and method for scrambling and time-hopping in an ultra-wideband wireless network. In one embodiment, a wireless device includes a symbol mapper and a dynamic chip scrambler. The dynamic chip scrambler is configured to scramble each of a plurality of consecutive bursts of a time-hopped packet according to a pseudo-random scrambling sequence that varies from burst to burst.
    Type: Application
    Filed: April 15, 2011
    Publication date: October 20, 2011
    Applicant: TEXAS INSTRUMENTS INCORPORATED
    Inventors: June Chul ROH, Anuj BATRA, Srinath HOSUR
  • Patent number: 8018267
    Abstract: Provided is a frequency conversion mixer. The frequency conversion mixer includes a transconductance stage, a switching stage, a load stage, a current bleeding circuit, and a bias stage. The transconductance stage receives an RF signal, and outputs a current corresponding to a voltage of the RF signal. The switching stage switches the current which is outputted from the transconductance stage in response to a local oscillation signal, for frequency conversion the RF signal into an intermediate frequency (IF) signal. The load stage is connected between the switching stage and a supply voltage terminal. The current bleeding circuit is connected parallel with the switching stage, especially, embodying inverter structure with transconductance stage to get not only current bleeding effect but also current reuse effect, and one resonant inductor for reducing noise which is generated in parasitic capacitance at node between transconductance stage and switching stage.
    Type: Grant
    Filed: June 18, 2010
    Date of Patent: September 13, 2011
    Assignees: Electronics and Telecommunications Research Institute, Industry-University Cooperation Foundation Hanyang Univ.
    Inventors: Yun-mo Kang, Tae-yeoul Yun, Hee-woo An, Chang Sun Kim, Yea Chul Roh, Seong Hoon Choi
  • Publication number: 20110156954
    Abstract: A GNSS navigation system and navigation method for determining user position, user velocity, and improved uncertainty metrics for position and velocity. A measurement engine in an applications processor of the system determines pseudorange and delta range values over each time period for each received satellite signal, and also determines measurement noise variances for both pseudorange and delta range for the individual signals. The satellite-specific pseudorange and delta range measurement variances are used to determine the position and velocity uncertainties by a position engine, either by way of a least-squares linearization or by way of an enhanced Kalman filter. The uncertainties may be communicated to the system user, or used in generating an integrated position and velocity result from both the GNSS navigation function and an inertial navigation system result.
    Type: Application
    Filed: December 29, 2009
    Publication date: June 30, 2011
    Applicant: TEXAS INSTRUMENTS INCORPORATED
    Inventors: June Chul Roh, Deric Wayne Waters