一种新的自由空间光通信调制方式——圆偏振位移键控

自由空间光通信(FSO)在开放的大气链路中传输光信号, 不可避免地会受到大气扰动和背景光噪声的影响, 导致系统的可靠性降低。为了抑制大气扰动等对FSO系统造成的不利影响, 提出一种新的光信号调制方式——圆偏振位移键控(CPOLSK)。该调制方式利用圆偏振光的两种旋光状态进行数据的传送, 接收端结合差分方法进行光信号接收。给出了CPOLSK的装置模型, 并对其性能进行了分析。与目前广泛采用的开关键控(OOK)、脉冲位置调制(PPM)方式相比, CPOLSK很好地抑制了背景光噪声的影响, 同时对光电探测器内部噪声也有一定的抑制效果。

A New Modulation Method in Free Space Optical Communication: Circle Polarization Shift Keying

In free space optical communication (FSO), optical signals transmit in the open air link. Inevitably, received signals are influenced by atmosphere disturbance and background noise, so the reliability of FSO system is reduced. In order to restrain adverse effects of atmosphere disturbance, a new modulation method of optical signal in FSO, which is named as circle polarization shift keying (CPOLSK), is proposed in this paper. In this modulation, two rotation states of circle polarization are used to denote “0” and “1” data , respectively, then the information transmission accomplished by transmitting rotation state time series. In the receiver, the signal is detected with difference method. The setting of CPOLSK is presented and the performance is analyzed. Compared with on-off-keying(OOK)and pulse position modulation(PPM) modulation methods, which are widely used in wireless communication systems, the CPOLSK modulation has more excellent capability in background noise suppressing and photodetector inherent noise limiting.