Effect of oscillator phase noise and processing delay in full-duplex OFDM repeaters

We study the performance of a non-regenerative OFDM repeater link impaired by oscillator phase noise which is modeled as a Wiener process. In particular, we compare two different repeater designs, namely the case of employing separate oscillators for down- and upconversion and the case of reusing a single oscillator for both purposes. When the repeater is implemented with only one oscillator, the repeater´s processing delay becomes a key parameter affecting the severity of spectral spreading caused by phase noise. In fact, we show that the transmit-side noise can partially revert the effect of receive-side noise when processing delay is short enough. Spectral spreading is first analyzed by calculating the power-spectral density of the excess phasor process due to imperfect oscillators. We also evaluate end-to-end transmission rate of the repeater link and study the degradation caused by inter-carrier interference from phase distortion in terms of the processing delay.