Proposal of photonic frequency-conversion method using bandpass sampling in multicarrier operated radio-on-fiber link

Recently, IF-band RF signal transmission over the fiber using optically supported upconversion/downconversion has attracted much attention, as it can avoid signal deterioration due to a dispersion effect, and a low-cost radio base station can be realized without using any RF mixer. The frequency shifting using the bandpass sampling is one of the candidates for frequency conversion of RF signals. This paper proposes an application of frequency shifting using bandpass sampling in a multicarrier-operated radio-on-fiber link. All multiband RF services in a radio-on-fiber link can be modulated and demodulated using by the IF-band MODEM at the control station in the multicarrier operation environment. When multiband RF signals are simultaneously frequency converted to distinct IF band, signal deterioration due to spectrum overlap is a serious problem. In this paper, an undesired alias suppression method without additional signal processing in the receiver is proposed. As a result of experimental investigation, the symbol error rate is improved from 0.5 to 0.003 in case of the received optical power of -23 dBm.