Pilot assisted SNR estimation in a non-coherent M-FSK receiver with a carrier frequency offset

Pilot-assisted estimation of signal-to-noise ratio (SNR) is considered for an orthogonal non-coherent M-ary FSK receiver having a carrier frequency offset (CFO) at the front end. The received signal is also corrupted by symbol-rate Rayleigh fading and additive white Gaussian noise. A two-step estimation procedure is designed by observing received data in the receiver. In the first step, an asymptotically unbiased estimate of CFO is obtained using a moments based approach. This estimate is then used to derive a maximum-likelihood estimator for the SNR. The Cramer Rao Bound for SNR has been derived to compare the overall estimator performance in terms of its variance.