This book provides a comprehensive exploration of the performance and reliability analysis of high-altitude unmanned platforms, including tethered high-altitude unmanned platforms. It introduces advanced mathematical models, methods, and algorithms that enhance reliability theory and strengthen the theoretical foundations of UAV-based aerial communication networks, essential for 5G, 6G, and future networks. The book presents innovative approaches, including Markov and semi- Markov processes, along with simulation models, to analyze complex systems and compute key reliability and performance metrics.

Dharmaraja Selvamuthu earned his Ph.D. degree in mathematics from the Indian Institute of Technology Madras, Chennai, in 1999. From 1999 to 2002, he was a postdoctoral fellow at the Department of Electrical and Computer Engineering, Duke University, USA. From 2002 to 2003, he worked as a research associate at TRLabs, Winnipeg, Canada. Since 2003, he has been with the Department of Mathematics at IIT Delhi, where he is currently a professor and has also been a joint faculty member at the Bharti School of Telecommunication Technology and Management since June 2013. He became a professor (HAG) in October 2020 and served as an institute chair professor from July 2019 to June 2024. He is co-author of a text book entitled "Introduction to Probability, Statistical Methods, Design of Experiments and Statistical Quality Control" in Springer (Second Edition, April 2024). Recently, he is the author of a text book entitled "Introduction to Stochastic Processes: Queues, Finance, and Credit Risk" in Springer, July 2025.

Vladimir M. Vishnevsky received his engineering degree in applied mathematics from the Moscow Institute of Electronics and Mathematics in 1971, followed by a Ph.D. (1974) and D.Sc. (1988) in telecommunication networks from the V. A. Trapeznikov Institute of Control Sciences, Russian Academy of Sciences (ICS RAS). He became a full professor at ICS RAS in 1989 and at the Moscow Institute of Physics and Technology in 1990. In 2019, he was awarded the title “Honored Scientist of the Russian Federation” by presidential decree.

Raina Raj received her Ph.D. in stochastic modeling of cellular networks with optimization methods from the Central University of Rajasthan. Since 2022, she has been associated with IIT Delhi, initially as a postdoctoral fellow in the Department of Mathematics and since 2023 with the Bharti School of Telecommunication Technology and Management. Currently, she is Assistant Professor at Department of Mathematics & Statistics, Central University of Punjab. She has authored over 25 research papers and a book chapter, with research interests spanning wireless resource management, high-altitude platforms, game theory, queueing theory, cybersecurity, and optimization.

Vladimir V. Rykov earned his D.Sc. in physics and mathematics from Moscow State University in 1990. He has served as a full professor at the Gubkin Russian State Oil and Gas University and at RUDN University. He is affiliated with the Moscow Mathematical Society, the Russian Actuarial Society, and Kappa Mu Epsilon. He is also a member of the Gnedenko Forum and the International Academy of Informatization. His research interests include controllable queueing systems and reliability theory.

Nika M. Ivanova obtained her B.Sc. in business informatics and M.Sc. in applied mathematics and informatics from RUDN University in 2017 and 2019, respectively, and earned her Ph.D. in physics and mathematics in 2023. She has received scholarships from the Government and the President of the Russian Federation. Since 2020, she has been a senior research fellow at the Network Systems Control Laboratory, ICS RAS.

Dmitry V. Kozyrev earned his B.Sc. and M.Sc. in applied mathematics and informatics from the RUDN University in 2005 and 2007, respectively, and in 2013 received his Ph.D. in Theoretical Foundations of Computer Science. He has been associated with the RUDN University since 2007 and currently serves as an associate professor in the Department of Probability Theory and Cybersecurity. He also served as the vice director of the Institute of Applied Mathematics and Communications Technology, RUDN University, from 2017 to 2019.

Author or co-author of more than 120 published research works, including 3 monographs and 3 university textbooks; editor of over 30 proceedings books. His research interests include applied probability, stochastic modeling, simulation, reliability assessment and performance analysis, sensitivity analysis, k-out-of-n models.