为提高光纤无线电（RoF）系统的传输性能，提出了一种基于概率-几何混合整形的圆形正交振幅调制（PS-GS-Cir-MQAM）矢量太赫兹信号传输方案。在Matlab和VPI环境下联合仿真分析了130 GHz波段PS-GS-Cir-MQAM信号在强度调制器（IM）和同相/正交（I/Q）调制器级联的RoF系统中信号的传输性能，并比较分析了信号的误码性能在不同整形方法后的改善效果。结果表明，提出的PS-GS-Cir-MQAM太赫兹信号的误码性能均优于其他三种整形格式。其中PS-GS-Cir-32QAM信号的误码性能提升效果最为明显，相比其他三种整形格式，分别提升了0.88、1.40、2.48 dB的信号功率增益。尤其是在克服光器件和光纤的非线性效应方面，PS-GS-Cir-MQAM的矢量太赫兹信号具有更大的传输优势。

A circular quadrature amplitude modulation based on probability-geometric hybrid shaping (PS-GS-Cir-MQAM) vector terahertz (THz) signal transmission scheme is proposed to improve the transmission performance of a radio-over-fiber (ROF) transmission system. The transmission performance of the 130 GHz band PS-GS-Cir-MQAM signal in an RoF system with an intensity modulator (IM) and in-phase/quadrature (I/Q) modulator cascaded is analyzed via co-simulation in Matlab and VPI, and the signal transmission performance is compared and analyzed. The improvement effect of different shaping methods on the error code performance is evaluated. The results show that the error performance of the proposed PS-GS-Cir-MQAM THz signal is better than those of the other three shaping formats. Among them, the PS-GS-Cir-32QAM THz signal shows the most significant improvement in error performance. Compared with the other three shaping formats, the signal power gain increases by 0.88, 1.4, and 2.48 dB,respectively. The proposed hybrid shaping-based vector THz signal is advantageous in terms of transmission; specifically, it overcomes the nonlinear effects of optical devices and optical fibers.