Fig. 1. NLOS UV communication model

Fig. 2. UV beacon communication model. (a) Two-dimensional model; (b) three-dimensional model

Fig. 3. Communication coverage of a wireless UV beacon node in two- and three-dimensional spaces. (a) Two-dimensional space; (b) three-dimensional space

Fig. 4. Four-node positioning model

Fig. 5. Movement status of two drones

Fig. 6. Vector sharing method for collision avoidance

Fig. 7. Received signal strength of four ranging methods

Fig. 8. Received signal strength of different transmitting and receiving angles under NLOS

Fig. 9. UV ranging error at different ranging modes

Fig. 10. Positioning results of two- and three-dimensional spaces. (a) Two-dimensional space; (b) three-dimensional space

Fig. 11. 2D and 3D spatial positioning accuracy

Fig. 12. Two UAV collision avoidance paths

Fig. 13. Distance between two UAVs