An iterative and joint estimation of SNR and frequency selective channel for OFDM systems

International audienceThis paper proposes an iterative method for a joint estimation of the signal-to-noise ratio (SNR) and the frequency selective transmission channel in OFDM systems. The noise variance is estimated using a pilot preamble scheme, with the minimum mean square error (MMSE) criterion which requires the channel estimation. The channel estimation uses the Linear MMSE (LMMSE) method which requires the noise variance estimation. As each estimatior feeds the other one, an iterative algorithm is proposed.We prove that this algorithm converges for any non-null initialization value. Simulations show the validity of the method with a very low number of iteration for both SNR and channel estimation. We show that the number of pilot symbols in the preamble with respect to the performance of SNR estimation is improved compared to existing SNR estimation methods. Our approach also requires only one pilot symbol. Furthermore, for a given BER value, the SNR gap between perfect estimation and our proposed method is less than 0.5 dB