Fast Start-Up Decision Feedback Equalizer Based on Channel Estimation for 8VSB DTV System

Abstract

This paper presents a robust fast start-up decision feedback equalizer (DFE) based on channel estimation for eight-level vestigial sideband digital television (8VSB DTV) system. We propose two techniques to achieve the fast start-up equalization without an error propagation. The first one is a channel estimation scheme, which consists of a tap-selected correlation and a modified least-mean-square algorithm, to estimate accurately long and complex channels. The second one is a general training DFE (GT-DFE) to overcome the shortage of a training sequence in the VSB signal. The GT-DFE calculates the coefficients of the DFE prior to the equalization with the knowledge of the channel estimation, reference tap (symbol timing of DFE) and its position, i.e., decision delay, in the feedforward filter (FFF). Simulation results show that the proposed channel estimation scheme provides a reliable performance comparable to that of conventional schemes. It is also shown that a GT-DFE-based DFE provides 7dB~9 dB higher start-up signal to interference-plus-noise ratio (SINR) as compared to the DFE without the GT-DFE in severe channels. Moreover, the GT-DFE-based DFE provides a faster convergence speed as much as 2.4times106~6times10 6 symbols to converge within 1 dB of the final SINR as compared to the DFE without the GT-DFE