On time-domain OFDM channel estimation: use of pilots correlation for digital video roadcasting (DVB) cable receiver

In this paper, an improved OFDM time domain channel estimation algorithm is proposed for (DVB) Cable receivers. The algorithm exploits time domain-pilot correlation (TD-PC) to estimate the channel impulse response (CIR). In this method, a certain combination of positive and negative sub-pilot tones is used to generate the null carriers in each OFDM symbol. The first set contains all positive periodic carriers; while the second contains negative carriers at null positions. Then we take advantage of these positive periodic sub-pilot carriers in time-domain correlation with received signal which gives rise to zero correlation of data to positive pilot subcarrier over the length of cyclic prefix. The performance of proposed TD-PC algorithm is evaluated under DVB-Cable-2 fading channel models in digital cable TV receivers. Simulation results show that the proposed algorithm provides better accuracy in term of Mean Square Error (MSE) over conventional time and frequency domain channel estimators. It is shown that proposed TD-PC algorithm has a comparable performance to Cramer-Rao bound (CRB) in low signal to noise ratio (SNR) regime.