Patents by Inventor Lakshminarayanan Raghavendran

Lakshminarayanan Raghavendran 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).

  • Robust channel estimation of OFDM systems
    Patent number: 9231836
    Abstract: A system and method for estimating a channel in wireless communication systems using Orthogonal Frequency Division Multiplexing (OFDM). From the received OFDM symbols, Maximum Likelihood (ML) estimate of the channel frequency response is obtained at the pilot locations. A hypothesis test is performed on the ML estimates and the outcome of the hypothesis test is used to decide a shrinkage target. Biased estimation methods are used to shrink the ML estimates towards the shrinkage target to obtain better estimates of the channel frequency response at the pilot locations and these estimates are interpolated using a Filter to get a set of complete estimates of the channel over the resource block. The Filter is an Empirical Weiner Filter or a robust 2D-MMSE filter and the biased estimation is done using either a James-Stein (JS) estimator or a shrinkage estimator or an empirical Bayes estimator.
    Type: Grant
    Filed: June 11, 2010
    Date of Patent: January 5, 2016
    Assignee: Centre of Excellence in Wireless Technology
    Inventors: Sheetal Kalyani, Lakshminarayanan Raghavendran, Krishnamurthi Giridhar
  • Robust Channel Estimation of OFDM Systems
    Publication number: 20130215826
    Abstract: A system and method for estimating a channel in wireless communication systems using Orthogonal Frequency Division Multiplexing (OFDM). From the received OFDM symbols, Maximum Likelihood (ML) estimate of the channel frequency response is obtained at the pilot locations. A hypothesis test is performed on the ML estimates and the outcome of the hypothesis test is used to decide a shrinkage target. Biased estimation methods are used to shrink the ML estimates towards the shrinkage target to obtain better estimates of the channel frequency response at the pilot locations and these estimates are interpolated using a Filter to get a set of complete estimates of the channel over the resource block. The Filter is an Empirical Weiner Filter or a robust 2D-MMSE filter and the biased estimation is done using either a James-Stein (JS) estimator or a shrinkage estimator or an empirical Bayes estimator.
    Type: Application
    Filed: June 11, 2010
    Publication date: August 22, 2013
    Inventors: Sheetal Kalyani, Lakshminarayanan Raghavendran, Krishnamurthi Giridhar