基于相位调制器产生六倍频光毫米波的OFDM信号光传输系统研究

提出了两个并行相位调制器产生六倍频光毫米波并传输正交频分复用信号的全双工光纤无线通信系统.将2.5 Gbt/s的正交频分复用信号调制到60 GHz光毫米波上.从理论上分析了毫米波产生的原理,并分别模拟了毫米波信号承载OOK信号和正交频分复用信号在光纤中的传输性能.从而验证系统的可行性.仿真模拟结果表明,在光纤无线通信系统中,正交频分复用比非归零码更具有优势.     

Influence of the modulation index of Mach-Zehnder modulator on RoF link with ASK millimeter-wave signal

In this paper, the influence of the modulation index of LiNbO₃ Mach-Zehnder modulator on the radio over fiber (RoF) link based on single sideband (SSB) optical millimeter (mm)-wave with ASK signal is theoretically and numerically investigated. Our investigation shows that there exists an optimal modulation index to generate the SSB optical mm-wave with a maximal RF photocurrent. Although the fiber dispersion distorts the code form and degrades the performance of the RF signal demodulated from the SSB optical mm-wave after fiber transmission, it does not cause the closure of the eye diagram. However, the influence of the fiber dispersion becomes more obvious as the modulation index increases. For the duplex RoF link with the optical carrier of the uplink recovered from the downlink, a larger modulation index of the downlink causes a worse crosstalk from the downlink to the uplink.     

长距离和多模接入网络中低密度奇偶校验-正交频分复用的性能研究

研究了低密度奇偶校验编码与正交频分复用相结合的编码调制技术,从理论上分析了光纤链路中色散和频率选择性衰落的影响,并通过数值模拟仿真,比较了不同编码码率的编码调制信号在长距离单模光纤传输和多模光纤接入网络中的传输性能.仿真结果表明,采用码率为0.75的长码型非规则的低密度奇偶校验编码与正交频分复用相结合的编码调制技术更适合光纤通信系统中的长距离传输和多模接入网络.