Comparison of two FFT-based demodulation schemes for M-ary FSK

The authors examine the relative performance of two detection schemes for FFT (fast Fourier transform) demodulation of M-ary FSK (frequency shift keying). Specifically, they study the relative merits of detection based on a single bin power (scheme A) or powers from two bins (scheme B). Theoretical expressions for the error probabilities are derived for both schemes and verified by simulation. The conclusion is that scheme A is better at low offsets, up to about a third of the bin width, while scheme B is better at higher offsets. However, since summing bin powers requires additional computations, detection based on a single bin power is the recommended approach