Key Technologies and Development Trends of Free Space Optical UAV Communication Network
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摘要: 在当前电磁频谱拥堵和无线电干扰严重的情况下,基于自由空间光(FSO)的无人机(UAV)通信网络作为推进空天地一体化进程的重要一环,得到了学术界和工业界的广泛关注。与传统射频通信相比,FSO通信具有高数据传输速率、低时延和高安全性等优势。然而,FSO链路易受大气信道条件影响,同时UAV高移动性、网络高动态性以及机载资源的有限性给FSO的稳定连接与可靠通信带来了巨大挑战。因此,该文在介绍了FSO传输特性的基础上,着重分析了提升基于FSO的UAV通信网络稳定性与通信质量的关键技术,在此基础上,归纳出高可靠、强智能、长续航的发展趋势,以期为基于FSO的UAV通信网络发展提供参考与借鉴。Abstract: Considering the electromagnetic spectrum congestion and serious interference, the Free Space Optical (FSO)-based Unmanned Aerial Vehicle (UAV) communication network constitutes an important part for the space-air-ground integration, attracting substantial attention from both academia and industry. Compared to radio frequency communication, FSO communication is benefited from high data rate, low latency and high security. However, the FSO link is susceptible to atmospheric environment, while the mobile UAV dynamics topology and limited resources bring further challenges. Therefore, this paper first introduces the FSO transmission characteristics and then focuses on the key technologies to enhance stability and quality of FSO-based UAV networks. Furthermore, the development trend of FSO-based UAV network, in terms of high reliability, strong intelligence and long endurance is analyzed.
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表 1 分子吸收系数表
波长(nm) 分子吸收(dB/km) 550 0.13 690 0.01 850 0.41 1550 0.01 表 2 大气粒子散射过程表
类型 半径(μm) 散射过程 空气分子 0.0001 瑞利 雾霾粒子 0.01~1.00 瑞利-米氏 雾滴 1~20 三重几何 雨 100~10000 几何 雪 1000~5000 几何 冰雹 5000~50000 几何 表 3 大气湍流类型
条件 类型 特点 漩涡尺度大于发射机光束大小 光束漂移 漩涡以随机方式从原始路径整体偏转光束,导致指向误差,光束错开接收机区域。 漩涡尺度等于发射机光束大小 光束闪烁 漩涡起到透镜作用,使入射光束聚焦并导致接收机处的光辐射照度波动。 漩涡尺度小于发射机光束大小 光束扩散 光束的一小部分被独立衍射和散射,导致接收功率密度降低以及接收光束的波前扭曲。 -
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