A Comparative Study of Channel Estimation Techniques for OFDM in DVB-T2

Abstract

pilot symbol assisted channel estimation is a well-known multicarrier technique for high rate transmission over wireless frequency selective fading channels. In this paper a comparative study of channel estimation techniques is presented based on a pilot arrangement used in the second generation for Digital Video Broadcasting Terrestrial (DVBT2) system in time-varying frequency-selective fading channels. A modified method based on Domain Transform Least Square Estimation (DTLSE) has been proposed which reduces the computational complexity by avoiding the use of the matrix inversion .The estimation matrix size for obtaining Channel Impulse Response (CIR) depends only on the length of the channel not on the number of pilot subcarriers nor the size of OFDM symbol. Two Dimensional Linear Interpolation (2-DLI) is discussed which performs better than one Dimensional Linear Interpolation (1-DLI)but suffers from long processing delay and higher sensitivity to Doppler frequency shifts. The Minimum Mean Squared Error (MMSE) channel estimation is also considered as a reference method because it has a good performance close to the perfect estimation at the cost ofhigh computational complexity and the necessity of prior knowledge ofchannel statistics. The proposed method is compared with three other methods DTLSE, 2-DLI and MMSE.The proposed method provesto give a better performance compared to the other methods which suffer from either a much higher computational load or less robustness to Doppler shifts.