Renzhi Yuan (Member, IEEE) received the B.S. degree in mechanical engineering from Tongji University, Shanghai, China, in 2011, the M.S. degree in precision instrument from Tsinghua University, Beijing, China, in 2017, and the Ph.D. degree in electrical engineering from the University of British Columbia, Kelowna, BC, Canada, in 2021. He is currently a distinguished research fellow in the School of Information and Communication Engineering and the State Key Laboratory of Networking and Switching Technology of Beijing University of Posts and Telecommunications. His research interests include the space-air-ground integrated communications, wireless optical communications, and quantum communications.Zhifeng Wang received the B.S. degree from Shanghai University, Shanghai, China, and the M.S. degree from Hainan University, Haikou, China, in 2015 and 2018, respectively. He is currently working toward the Ph.D. degree in State Key Laboratory of Networking and Switching Technology (SKL-NST), School of Information and Communication Engineering, Beijing University of Posts and Telecommunications (BUPT). His research interests include ultraviolet communications, full-duplex, and multiple access technologies.

• Chapter 1 Introduction to Ultraviolet Communications.- Chapter 2 Channel Modeling of Ultraviolet Communications.- Chapter 3 Achievable Information Rates of Ultraviolet Communications.- Chapter 4 Full-Duplex Ultraviolet Communications.- Chapter 5 Relay-Assisted Ultraviolet Communications.- Chapter 6 None-Line-of-Sight Ultraviolet Positioning.- Chapter 7 Future Prospects of Ultraviolet Communications.

Renzhi Yuan (Member, IEEE) received the B.S. degree in mechanical engineering from Tongji University, Shanghai, China, in 2011, the M.S. degree in precision instrument from Tsinghua University, Beijing, China, in 2017, and the Ph.D. degree in electrical engineering from the University of British Columbia, Kelowna, BC, Canada, in 2021. He is currently a distinguished research fellow in the School of Information and Communication Engineering and the State Key Laboratory of Networking and Switching Technology of Beijing University of Posts and Telecommunications. His research interests include the space-air-ground integrated communications, wireless optical communications, and quantum communications.Zhifeng Wang received the B.S. degree from Shanghai University, Shanghai, China, and the M.S. degree from Hainan University, Haikou, China, in 2015 and 2018, respectively. He is currently working toward the Ph.D. degree in State Key Laboratory of Networking and Switching Technology (SKL-NST), School of Information and Communication Engineering, Beijing University of Posts and Telecommunications (BUPT). His research interests include ultraviolet communications, full-duplex, and multiple access technologies.

• Chapter 1 Introduction to Ultraviolet Communications.- Chapter 2 Channel Modeling of Ultraviolet Communications.- Chapter 3 Achievable Information Rates of Ultraviolet Communications.- Chapter 4 Full-Duplex Ultraviolet Communications.- Chapter 5 Relay-Assisted Ultraviolet Communications.- Chapter 6 None-Line-of-Sight Ultraviolet Positioning.- Chapter 7 Future Prospects of Ultraviolet Communications.

Renzhi Yuan (Member, IEEE) received the B.S. degree in mechanical engineering from Tongji University, Shanghai, China, in 2011, the M.S. degree in precision instrument from Tsinghua University, Beijing, China, in 2017, and the Ph.D. degree in electrical engineering from the University of British Columbia, Kelowna, BC, Canada, in 2021. He is currently a distinguished research fellow in the School of Information and Communication Engineering and the State Key Laboratory of Networking and Switching Technology of Beijing University of Posts and Telecommunications. His research interests include the space-air-ground integrated communications, wireless optical communications, and quantum communications.Zhifeng Wang received the B.S. degree from Shanghai University, Shanghai, China, and the M.S. degree from Hainan University, Haikou, China, in 2015 and 2018, respectively. He is currently working toward the Ph.D. degree in State Key Laboratory of Networking and Switching Technology (SKL-NST), School of Information and Communication Engineering, Beijing University of Posts and Telecommunications (BUPT). His research interests include ultraviolet communications, full-duplex, and multiple access technologies.

• Chapter 1 Introduction to Ultraviolet Communications.- Chapter 2 Channel Modeling of Ultraviolet Communications.- Chapter 3 Achievable Information Rates of Ultraviolet Communications.- Chapter 4 Full-Duplex Ultraviolet Communications.- Chapter 5 Relay-Assisted Ultraviolet Communications.- Chapter 6 None-Line-of-Sight Ultraviolet Positioning.- Chapter 7 Future Prospects of Ultraviolet Communications.