Abstract
The reciprocity of the atmospheric turbulence channel in the bidirectional atmospheric laser propagation link is experimentally tested. The bidirectional transceiving coaxial atmospheric laser propagation link is built by using a hot air convection-type atmospheric turbulence emulation device with adjustable turbulence intensity. The influence of different turbulence intensities on the instantaneous-fading correlation of channel is analyzed by the spot characteristics. When there is no atmospheric turbulence in the bidirectional transceiving coaxial atmospheric laser propagation link, the value of channel instantaneous fading correlation coefficient was merely 0.023, which indicates we did not find any reciprocity in the optical channel. With the increment in turbulence intensity, the channel instantaneous fading correlation coefficient presented a constant increasing trend and then tended to be stable around 0.9 in the end. At this moment, the similarity of the instantaneous change trends for these two receiving terminal optical signals, and the consistency of their probability density function, indicates that there is good reciprocity between the bidirectional atmospheric turbulence optical channels. With the increase in the optical signal scintillation factor, we can obtain the result where the correlation coefficient value decreases accordingly.
Highlights
Published: 14 April 2021In the past few decades, atmospheric space laser communication technology has developed rapidly, which combines the characteristics of optical fiber communication and other wireless communication methods
According to the bidirectional transceiving coaxial atmospheric laser propagation link shown in Figure 4, the experimental link was built to carry out the bidirectional coaxial atmospheric laser propagation experiment
The temperature gradient during the experiment was 10 ◦ C, that is, when the temperature of the atmospheric turbulence emulation tank box increased by 10 ◦ C, the two terminals of the bidirectional atmospheric laser propagation link simultaneously collected the power of a group of received spot signals and stored them in the computer through the acquisition card
Summary
In the past few decades, atmospheric space laser communication technology has developed rapidly, which combines the characteristics of optical fiber communication and other wireless communication methods. In other words, when the channel is in a fixed state, the channel state of the return propagation is consistent with the channel state of the outbound propagation, and the channel state information (CSI) can be obtained at the transmitting end, so the channel is reciprocal In this way, the adaptive optics technology can correct the wavefront distortion caused by atmospheric turbulence, and reduce the additional overhead caused by establishing a dedicated channel state information feedback channel. It is significant to measure the related characteristics of the instantaneous fading of the bidirectional atmospheric laser propagation link channel. The similarity of the instantaneous change trends for these two receiving terminal optical signals, and the consistency of probability density function, indicates that there is a good reciprocity between bidirectional atmospheric turbulence optical channels.
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