Patents by Inventor Levent Demirekler

Levent Demirekler 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).

  • Method and apparatus for peak to average power ratio reduction for orthogonal frequency division multiplex systems
    Patent number: 7292639
    Abstract: A multi-stage signal processing method is provided that reduces the Peak to Average Power Ratio (PAPR) of an Orthogonal Frequency Division Multiplexed (OFDM) signal without increasing the bit error rate of the system. The multi-stage processing system apportions the tones into a number of types, and processes the tones in an order and by a process consistent with their determined type. Advantageously, preprocessing of the time domain signal may be used to condition the data tones for optimal PAPR reduction during the multi-stage process.
    Type: Grant
    Filed: June 5, 2003
    Date of Patent: November 6, 2007
    Assignee: Nortel Networks Limited
    Inventors: Levent Demirekler, Aleksandar Purkovic
  • Apparatus and method for echo cancellation
    Patent number: 7181001
    Abstract: An apparatus and method for echo cancellation that detects and tracks the active regions of the echo channel impulse response rather than the entire echo channel impulse response and uses this sparse model to cancel the echo component of the received signal. Two sets of filter coefficients are used, one to remove and track the active regions and one to detect the active regions.
    Type: Grant
    Filed: December 30, 2004
    Date of Patent: February 20, 2007
    Assignee: Nortel Networks Limited
    Inventors: Levent Demirekler, Aleksandar Purkovic
  • Apparatus and method for echo cancellation
    Patent number: 6980646
    Abstract: An apparatus and method for echo cancellation that detects and tracks the active regions of the echo channel impulse response rather than the entire echo channel impulse response and uses this sparse model to cancel the echo component of the received signal. Two sets of filter coefficients are used, one to remove and track the active regions and one to detect the active regions.
    Type: Grant
    Filed: October 12, 2001
    Date of Patent: December 27, 2005
    Assignee: Nortel Networks Limited
    Inventors: Levent Demirekler, Aleksandar Purkovic
  • Apparatus and method for echo cancellation
    Publication number: 20050117739
    Abstract: An apparatus and method for echo cancellation that detects and tracks the active regions of the echo channel impulse response rather than the entire echo channel impulse response and uses this sparse model to cancel the echo component of the received signal. Two sets of filter coefficients are used, one to remove and track the active regions and one to detect the active regions.
    Type: Application
    Filed: December 30, 2004
    Publication date: June 2, 2005
    Inventors: Levent Demirekler, Aleksander Purkovic