Statistics and Error Performance of Orthogonal Frequency-Division Multiplexing over Nakagami-m Fading Channels

In this contribution we first derive the correlation coefficient of two subcarriers in multicarrier systems using cyclic-prefixing (CP) for inter-symbol interference (ISI) suppression and inverse fast Fourier transform (IFFT)/fast Fourier transform (FFT) for multicarrier modulation/demodulation. It can be shown that two subcarriers spaced far away may experience highly correlated fading. Then, the probability density function (PDF) of fading amplitudes of subcarrier signals is derived, showing that the PDF either obeys Rayleigh distribution or appears in irregular distribution. Finally, a simple closed-form bit error rate (BER) expression is obtained for orthogonal frequency-division multiplexing (OFDM) systems. This closed-form BER expression is very general, suitable for communications environments having different frequency selectivity and possibly different channel quality.