In this work, we propose adaptive frequency-domain biased estimation algorithms with mechanisms to automatically adjust the shrinkage factors. The proposed estimation algorithms improve the performance of the conventional least squares (LS) estimator in terms of mean-squared error (MSE), while requiring a very modest increase in complexity. An extension of the Cramer-Rao Lower Bound (CRLB) is computed in order to serve as a performance benchmark for the MSE performance of the biased estimators. We consider an application of the proposed algorithms to single-carrier frequency domain equalization (SC-FDE) of direct-sequence ultra-wideband (DS-UWB) systems, in which the channel estimation is performed by the proposed algorithms. The simulation results show that the proposed algorithms significantly outperform existing methods.
['Sheng S. Li', 'Rodrigo C. de Lamare', 'Martin Haardt']
Adaptive frequency-domain biased estimation algorithms with automatic adjustment of shrinkage factors