Bit error probability of OFDM system over frequency nonselective fast Rayleigh fading channels

The variation in the channel impulse response during one OFDM symbol, which occurs in fast fading channel environments, destroys the orthogonality bet ween the subcarriers. As a result, a complicated multiple distortion and an extra additive distortion component are introduced. A theoretical derivati on of the BER formula is presented, which involves a proposed method for ca lculating the probability density function (PDF) of the sum of N (N greater than or equal to 3) correlated Rayleigh random variables (RVs). The result s obtained using the derived EER formula agree well with the simulation res ults.