Subspace-based noise variance and SNR estimation for OFDM systems [mobile radio applications]

Noise variance and hence signal to noise ratio (SNR) estimates are very important for the channel quality control in communication systems. Noting that in mobile communications the multipath time delays are slowly varying in time, in this paper we derive a subspace-based estimation method for orthogonal frequency division multiplexing (OFDM) systems, which is based on an eigenvector decomposition of the estimated channel correlation matrix. Simulation results show that the proposed estimator can obtain accurate real time measurements of the noise variance and SNR after an observation interval of about 20 OFDM symbols for various fading channels.

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