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 between the subcarriers. As a result, a complicated multiple distortion and an extra additive distortion component are introduced. A theoretical derivation of the BER formula is presented, which involves a proposed method for calculating the probability density function (PDF) of the sum of N (N⩾3) correlated Rayleigh random variables (RVs). The results obtained using the derived BER formula agree well with the simulation results