40GHz光纤无线通信系统中开关键控与正交频分复用信号传输性能的比较

Performance Comparsion between On-Off Keying and Orthogonal Frequency Division Multiplexing Signals in 40 GHz Radio-Over-Fiber Systems

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.