Influence of oscillator phase noise and clipping on OFDM for terrestrial broadcasting of digital HDTV

Phase noise causes significant degradation of the performance of a high order quadrature amplitude modulation (QAM) system in conjunction with an orthogonal frequency division multiplexing (OFDM) procedure. Moreover, an OFDM signal has a non-constant envelope with large instantaneous amplitude peaks and there will be a need to limit these large variations of the signal. This paper describes a model for oscillator phase noise distortion due to the receiver tuner and presents some expressions for amplitude clipping introduced by the nonlinear high power amplifier in the transmitter and by the automatic gain control in the receiver. Our simulations show the influences on an uncoded and on a trellis-coded system for transmitting digital high-definition television (HDTV) signals.