| Based on wave radiation transmission theory in random medium, several non-line-of-sight ultraviolet propagation models are studied in this thesis. Based on these models, non-line-of-sight ultraviolet propagation characteristics under different working modes and complicated weather conditions are discussed in detail.The main works are as follows:Firstly, the simple atmospheric transmission model is meliorated under the consideration of the absorption of oxygen. With the help of Modtran, we analyze the effect of different atmospheric components on the UV transmittance. The shortage of the simple atmospheric transmission model is then discussed. Combined with the small particle scattering theory, the simple atmospheric transmission model is given.Secondly, Ultraviolet atmospheric transmissions under different conditions are calculated by using Modtran, respectively. Influences of several factors such as distance of transmission and height of observer on the UV atmospheric transmission are analyzed. Moreover, influencing factors of weather conditions, such as seasons, cloud and rain, are also analyzed.Thirdly, the influence of the elevation angle and the half-field of view of the receiver and transmitter, the communication distances on ultraviolet communication system are discussed based on the single-scatter model. Besides, factors such as visibility and scattering phase function are also analyzed. At last, a simplified form of the single-scatter model is given.Finally, Multi-scatter model is established based on the Monte Carlo method. Then the model is ameliorated by using the point probability method. At the same time, the process of local coordinate transformation and the receiving judgment of detector in the simulation are given. Computing efficiency of different models is compared with each other. At last, impact of the complex weather, obstacle and difference of the sending and receiving height on the NLOS UV communication is analyzed. |
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