Time-variant distortions in OFDM

In this letter we analyze the degradation of orthogonal frequency division multiplexing (OFDM) signals from time-variant distortions like carrier and sampling frequency offset, Doppler spread and oscillator phase noise. We pr opose a novel analytical framework in the: discrete-time domain based on th e FFT demodulation of a single OFDM symbol and unify previous with some new results. Exact definitions of the signal-to-subcarrier-interference ratio (SIR) and the effective signal-to-noise ratio (SNR) are given and evaluated for a HIPERLAN/2 system.