SNR estimation algorithm based on the preamble for OFDM systems in frequency selective channels

We propose a new SNR estimation method based on the preamble for OFDM systems in frequency selective channels. The OFDM training symbols in the preamble are equalized by the known data in frequency domain and employed to estimate the noise variance. The second order moments of the received symbols are used to estimate the signal plus noise power in the OFDM packets. The SNRs on the subchannels and the average SNR of the packets can all be estimated. Simulation results show that the proposed method is robust to frequency selectivity in wireless channels, and its performance is considerably improved compared with the available methods.

I. Introduction

Signal-To-Noise RATIO (SNR) estimation is very important for wireless OFDM systems since the proper operations of many key techniques for improving system performance, such as adaptive coding and modulation [1], soft decoding procedures [2], mobile assisted handoff, and channel assignment [3], are strongly dependent on the correct estimation of SNR.