# A Novel System of Mixed RF/FSO UAV Communication Based on MRR and RIS by Adopting Hybrid Modulation
[PERSON]  
1 Guangdong Provincial Key Laboratory of Nanophotonic Functional Materials and Devices, Guangzhou 510006, China; [EMAIL_ADDRESS] (M.J.); [EMAIL_ADDRESS] (M.J.); [EMAIL_ADDRESS] (W.L. ); [EMAIL_ADDRESS] (R.W. ); [EMAIL_ADDRESS] (Z.W. ); [EMAIL_ADDRESS] (D.D.) [PERSON]  
1 Guangdong Provincial Key Laboratory of Nanophotonic Functional Materials and Devices, Guangzhou 510006, China; [EMAIL_ADDRESS] (M.J.); [EMAIL_ADDRESS] (M.J.); [EMAIL_ADDRESS] (W.L. ); [EMAIL_ADDRESS] (R.W. ); [EMAIL_ADDRESS] (Z.W. ); [EMAIL_ADDRESS] (D.D.) [PERSON]  
1 Guangdong Provincial Key Laboratory of Nanophotonic Functional Materials and Devices, Guangzhou 510006, China; [EMAIL_ADDRESS] (M.J.); [EMAIL_ADDRESS] (M.J.); [EMAIL_ADDRESS] (W.L. ); [EMAIL_ADDRESS] (R.W. ); [EMAIL_ADDRESS] (Z.W. ); [EMAIL_ADDRESS] (D.D.) [PERSON]  
1 Guangdong Provincial Key Laboratory of Nanophotonic Functional Materials and Devices, Guangzhou 510006, China; [EMAIL_ADDRESS] (M.J.); [EMAIL_ADDRESS] (M.J.); [EMAIL_ADDRESS] (W.L. ); [EMAIL_ADDRESS] (R.W. ); [EMAIL_ADDRESS] (Z.W. ); [EMAIL_ADDRESS] (D.D.) [PERSON]  
1 Guangdong Provincial Key Laboratory of Nanophotonic Functional Materials and Devices, Guangzhou 510006, China; [EMAIL_ADDRESS] (M.J.); [EMAIL_ADDRESS] (M.J.); [EMAIL_ADDRESS] (W.L. ); [EMAIL_ADDRESS] (R.W. ); [EMAIL_ADDRESS] (Z.W. ); [EMAIL_ADDRESS] (D.D.) [PERSON]  
1 Guangdong Provincial Key Laboratory of Nanophotonic Functional Materials and Devices, Guangzhou 510006, China; [EMAIL_ADDRESS] (M.J.); [EMAIL_ADDRESS] (M.J.); [EMAIL_ADDRESS] (M.J.); [EMAIL_ADDRESS] (W.L. ); [EMAIL_ADDRESS] (R.W. ); [EMAIL_ADDRESS] (Z.W. ); [EMAIL_ADDRESS] (D.D.) [PERSON]  
1 Guangdong Provincial Key Laboratory of Nanophotonic Functional Materials and Devices, Guangzhou 510006, China; [EMAIL_ADDRESS] (M.J.); [EMAIL_ADDRESS] (M.J.); [EMAIL_ADDRESS] (M.J.); [EMAIL_ADDRESS] (W.L. ); [EMAIL_ADDRESS] (R.W. ); [EMAIL_ADDRESS] (Z.W. ); [EMAIL_ADDRESS] (D.D.) [PERSON]  
1 Guangdong Provincial Key Laboratory of Nanophotonic Functional Materials and Devices, Guangzhou 510006, China; [EMAIL_ADDRESS] (M.J.); [EMAIL_ADDRESS] (M.J.); [EMAIL_ADDRESS] (M.J.); [EMAIL_ADDRESS] (M.J.); [EMAIL_ADDRESS] (R.W. ); [EMAIL_ADDRESS] (Z.W. ); [EMAIL_ADDRESS] (D.D.) [PERSON]  
1 Guangdong Provincial Key Laboratory of Nanophotonic Functional Materials and Devices, Guangzhou 510006, China; [EMAIL_ADDRESS] (M.J.); [EMAIL_ADDRESS]. mobility of UAV can provide new opportunities for improving performance by dynamically adjusting relay position to best suit the environment for communication. Recently, modulating retro-reflector (MRR)'s FSO communication has been widely employed in UAV, optical wireless sensing networks, and spacecraft communication [8]. Specifically, MRR usually consists of an optical modulator and a passive retro-reflector, and the most commonly used retro-reflectors are the corner cube reflector (CCR) and the cat's eye reflector (CER) [9]. Compared to the traditional FSO communication, MRR FSO system offers significant advantage in terms of reducing the weight, size, and power constraints at one end of the FSO link [10]. In a conventional FSO communication system, precise ATP (acquisition, tracking, and pointing) system and laser transmitter must be deployed at both ends of the FSO link, which is limited when the UAV is working as a relay. However, when the MRR is installed at the relay, the ATP system and laser transmitter only needs to be placed at the other end of the FSO link, so the limitation problem of the relay is solved [11]. In [12], the effect of atmospheric turbulence on the performance of the MRR FSO system was investigated under correlated Gamma-Gamma fading channels, and adaptive threshold technique was chosen to improve the bit error rate (BER) performance. In [13], the BER of the MRR FSO system was analyzed over single and double Gamma-Gamma fading channels. Moreover, the outage probability, average BER and average channel capacity of the MRR FSO communication system were evaluated under different atmospheric turbulence in [14; 15; 16].