Patents by Inventor Alexandra Duel-Hallen

Alexandra Duel-Hallen 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).

  • Single-user decoder metrics for subtractive interference cancellation detectors in code-division multiple-access (CDMA) communication systems with time dependence variance residual multiple-access interference (RMAI)
    Patent number: 7035317
    Abstract: Improved branch metrics for Viterbi decoders in CDMA systems take into account the time dependency of the variance of the multiple access interference in any user's signal after the single-user detector, and the time dependency of the residual multiple access interference in any user's signal after subtractive interference cancellation is applied in two-stage detectors. The (residual) multiple access interference can be modeled as a Gaussian random variable with time dependent variance. Modeling the RMAI in such a way reduces the bit error rate in CDMA systems.
    Type: Grant
    Filed: September 20, 2001
    Date of Patent: April 25, 2006
    Assignee: North Carolina State University
    Inventors: Ayman Elezabi, Alexandra Duel-Hallen
  • Single-user decoder metrics for subtractive interference cancellation detectors in code-division multiple-access (CDMA) communication systems
    Publication number: 20020122392
    Abstract: Improved branch metrics for Viterbi decoders in CDMA systems take into account the time dependency of the variance of the multiple access interference in any user's signal after the single-user detector, and the time dependency of the residual multiple access interference in any user's signal after subtractive interference cancellation is applied in two-stage detectors. The (residual) multiple access interference can be modeled as a Gaussian random variable with time dependent variance. Modeling the RMAI in such a way reduces the bit error rate in CDMA systems.
    Type: Application
    Filed: September 20, 2001
    Publication date: September 5, 2002
    Inventors: Ayman Elezabi, Alexandra Duel-Hallen
  • Apparatus and method for echo characterization of a communication channel
    Patent number: 5577116
    Abstract: An apparatus for echo characterization or measurement includes a frequency domain adaptive filter for converging a plurality of filter coefficients based upon transmit and receive frequency domain transforms. The frequency domain adaptive filter preferably determines least mean square differences between estimated receive frequency domain transforms and the respective corresponding actual receive frequency domain transforms. The apparatus also preferably includes an echo characterization output portion for generating an echo characterization value for the communications channel. The echo characterization value may be one or both of echo path loss and echo delay. The apparatus preferably includes a gain normalization portion operatively connected to the adaptive filter for generating normalized gains of respective filter coefficients based upon spectral power of the respective transmit frequency domain transforms.
    Type: Grant
    Filed: September 16, 1994
    Date of Patent: November 19, 1996
    Assignee: North Carolina State University
    Inventors: Keith Townsend, Harish Punjabi, Alexandra Duel-Hallen, Samuel T. Alexander