从理论和实验两方面比较了光纤无线通信(ROF)系统中分别传输开关键控(OOK)与正交频分复用(OFDM)信号的性能。从理论上对产生的毫米波进行了色散效应分析,证明了在ROF系统中OFDM信号长距离传输后没有受到严重的码间干扰(ISI),只是毫米波信号的相位发生了变化;OOK信号受到了严重的码间干扰。实验证明在无色散补偿的情况下,2.5 Gb/s的OOK信号在单模光纤(SMF)中传输60 km后眼图完全闭合,误码率(BER)只能达到10-3,而采用OFDM信号传输130 km星座图仍然很好,误码率达到10-4,这说明在ROF系统中OFDM信号的传输性能要优于OOK。

The transimission performance of on-off keying (OOK) and orthogonal frequency division multiplexing (OFDM) signals in radio-over-fiber (ROF) system is experimentally and theoretically studied. The theoretical results show that OFDM signal is almost not affected by inter-symbol interference (ISI),only with the phase changed,where as OOK signal is seriously affected by ISI. The experiment results show that the eye diagram of 2.5 Gb/s OOK signal is closed when transmitting over 60 km in single mode fiber (SMF),and its bit error rate (BER) can only reach 10-3. The constellation of OFDM is clear when ttransmitting over 130 km with BER of 10-4. All theoretical and experimental results show that the performance of OFDM is better than that of OOK in ROF system.