Research On Optical Transmission Coding Technology In Light And Small UAVs Downlink Data Link

With the development of UAV technology,the application range of UAVs has become more and more extensive,and the amount of data collected by UAVs has also become larger and larger.As an important part of the UAV communication system,the downlink data link needs the support of high-speed communication links.In this paper,the atmospheric laser communication technology with high communication rate and strong anti-interference ability is introduced in response to the demand for high-speed and low-bit error rate data transmission in the downlink communication link of the UAV communication system.However,due to the serious impact of the atmospheric channel on the quality of laser communication,the use of channel coding technology in the communication system can effectively reduce the impact of the channel and reduce the bit error rate of the communication.This paper first analyzes the composition and key technologies of the UAV atmospheric laser communication system,and analyzes the specific impact of the atmospheric channel environment on laser communication.Then it mainly studies the channel coding technology and expounds the principle of common channel coding.The error rate of UAV's atmospheric laser communication system is analyzed,and the common channel coding methods are simulated and compared.It is concluded that LDPC coding is more suitable for UAV communication platform.Then,the LDPC code encoding and decoding algorithm is mainly studied,and the approximate lower triangular coding algorithm and logarithmic domain sum product decoding algorithm with relatively low computational complexity and strong performance are used,and the LDPC codes before and after improvement are simulated and compared.Finally,simulation and actual experiments of UAV atmospheric laser communication were conducted,the overall structure of the transmitting end was introduced,the laser transmitter at the transmitting end was designed,the selection of the laser and laser driver was described,and the composition of the modulation module and the coding module was introduced in detail The experimental comparison and verification of the communication quality improvement of LDPC codes before and after the improvement are carried out.Analysis of the experimental results shows that under the same communication environment,the optimized LDPC code can better improve the communication performance of the UAV atmospheric laser communication system,and the communication bit error rate can be maintained in the range of 10^-6.