Structured channel estimation based decision feedback equalizers for sparse multipath channels with applications to digital TV receivers

Abstract

In this paper, we investigate the performance of channel estimation based equalizers. We introduce two different channel estimation algorithms. Our first channel estimation scheme is a novel structured channel impulse response (CIR) estimation method for sparse multipath channels. The novel CIR estimation method was called blended least squares (BLS) which uses symbol rate sampled signals, based on blending the least squares based channel estimation and the correlation and thresholding based channel estimation methods. The second CIR estimation is called Variable thresholding (VT), and is based on improving the output of the correlation and thresholding based channel estimation method. We then use these two CIR estimates to calculate the decision feedback equalizer (DFE) tap weights. Simulation examples are drawn from the ATSC digital TV 8-VSB system. The delay spread for digital TV systems can be as long as several hundred times the symbol duration; however, digital TV channels are, in general, sparse where there are only a few dominant multipaths.