超奈奎斯特技术能大幅提升无线光通信系统的传输速率,但大气湍流严重影响超奈奎斯特无线光通信(FTN-OWC)系统的性能。详细研究了指数威布尔湍流信道中光强衰落对FTN-OWC系统平均容量和中断容量的影响,基于脉冲幅度调制推导了FTN-OWC系统的平均容量上界和中断概率,并采用广义超几何方法得到了其闭合表达式。仿真分析了加速因子、滚降系数、湍流强度和接收孔径对平均容量和中断容量的影响。结果表明,增强湍流会导致平均容量和中断容量减小,但可通过增大接收孔径和滚降系数进行提升。在弱湍流条件下,当接收孔径为25 mm、滚降系数为0.5、加速因子为2/3、平均信噪比为30 dB时,FTN-OWC的平均容量相比采用相同调制方式的奈奎斯特无线光通信系统提升了16.43%。

Faster-than-Nyquist technology can significantly improve the transmission rate of wireless optical communication system, but the atmospheric turbulence seriously affects the performance of faster-than-Nyquist wireless optical communication (FTN-OWC) system. In this paper, the influence of light intensity fading in exponential Weibull turbulent channel on the ergodic capacity and outage capacity of the FTN-OWC system is studied in detail. Based on pulse amplitude modulation, the ergodic capacity upper bound and outage probability of the FTN-OWC system are derived, and its closed-form expression is obtained by using the generalized hypergeometric method. In addition, the impact of acceleration factor, roll-off coefficient, turbulence intensity, and receiving aperture on the ergodic capacity and outage capacity is discussed. The results show that the ergodic capacity and outage capacity are reduced when the turbulence increases, but they can be improved by increasing the receiving aperture and roll-off coefficient. In the case of weak turbulence, the ergodic capacity of the FTN-OWC system is improved by 16.43% compared to the Nyquist wireless optical communication system using the same modulation method when the receiving aperture is 25 mm, the roll-off coefficient is 0.5, the acceleration factor is 2/3, and the average signal to noise ratio is 30 dB.