Novel SNR Estimation Teachnique In Wireless OFDM Systems

A novel front-end noise power and SNR estimation technique based on one OFDM preamble is proposed and compared with previously published SNR estimators – none of which are front-end estimators. This paper is extended and expanded version of our previous work. It provides complete mathematics and discussion of designed algorithms for front end SNR estimation. The proposed technique is divided into two parts. In the first part, SNR estimation technique for AWGN channel and wireless multipath channels is considered. In the second part, the proposed estimator takes into consideration the different noise power levels over the OFDM sub-carriers. The OFDM band is divided into several sub-bands using wavelet packet decomposition and noise in each sub-band is considered white. The secondorder statistics of the transmitted OFDM preamble are calculated in each sub-band and the noise power is estimated. The proposed estimator in first part is compared with Reddy estimator and Subspace based estimator for AWGN channel in terms of normalized mean square error and in the second part it is compared with Reddy’s estimator for colored noise in terms of mean square error (MSE). It is observed that current estimator gives better SNR estimates than Reddy and subspace estimators and can estimate local statistics of the noise power when the noise is colored.