Improving Secrecy Performance in Optical HAPS Communications Through Site Selection Under Harsh Weather Conditions

Öz

The physical layer security of non-terrestrial networks (NTNs) has recently garnered increasing attention from both academia and industry as the information can be intercepted in aerial transmissions, especially when an illegitimate user positions itself near the transmitter or receiver. To address this vulnerability, we investigate the secrecy performance of a high altitude platform station (HAPS) system using optical communications in the presence of an aircraft eavesdropper. Specifically, we assess the secrecy-reliability trade-off by considering both outage and interception probability, and explore the secrecy outage probability. In the proposed setup, we evaluate a practical scenario in which the HAPS communicates with multiple ground stations located at different altitudes, examining the system’s physical layer security performance for different types of attenuators including fog, clouds and air pollution. The findings indicate that weather conditions significantly affect the secrecy performance of optical HAPS communications. However, placing ground stations at higher altitudes or selection among multiple ground stations can improve the overall security performance of the system.

Anahtar Kelimeler

• HAPS systems
• optical communication
• physical layer security

Zorlu Hava Koşulları Altında Yer İstasyonu Seçimi Yoluyla Optik HAPS İletişiminde Gizlilik Başarımının Arttırılması

Öz

Son zamanlarda, havasal iletimlerde bilginin ele geçirilebilmesi nedeniyle, karasal olmayan ağların (non-terrestrial networks, NTNs) fiziksel katman güvenliği hem akademide hem de endüstride artan bir ilgiyle karşılanmaktadır; özellikle de yetkisiz bir kullanıcının vericiye veya alıcıya yakın bir konumda bulunması durumunda güvenlik riskleri artmaktadır. Olası güvenlik açıklarını ele almak amacıyla, bu çalışmada optik haberleşme kullanan bir yüksek irtifa platform istasyonu (high altitude platform station, HAPS) sisteminin gizlilik performansı, bir gizli dinleyicinin varlığı altında incelenmiştir. Özellikle, kesinti ve ele geçirilme olasılıklarını dikkate alarak önerilen sistemin gizlilik-güvenilirlik dengesi değerlendirilmiş ve gizlilik kesinti olasılığı hesaplanmıştır. Önerilen senaryoda, HAPS’ın farklı yüksekliklerde konumlanmış birden fazla yer istasyonu ile iletişim kurduğu pratik bir durumu ele alarak, sistemde sis, bulutlar ve hava kirliliği gibi farklı zayıflatıcı etmenlerin etkisi incelenmiştir. Sonuçlar, hava koşullarının optik HAPS iletişimlerinin gizlilik performansını önemli ölçüde etkilediğini göstermektedir. Ancak, yer istasyonlarının daha yüksek irtifalarda konumlandırılması veya birden fazla yer istasyonu arasından seçim yapılması sistemin genel güvenlik performansını arttırabilmektedir.

Anahtar Kelimeler

• HAPS sistemleri
• optik haberleşme
• fiziksel katman güvenlik

Kaynakça

1. F. J. Lopez-Martinez, G. Gomez, and J. M. Garrido-Balsells, “Physical-layer security in free-space optical communications,” IEEE Photonics Journal, vol. 7, no. 2, pp. 1–14, 2015.
2. P. V. Trinh, A. Carrasco-Casado, A. T. Pham, and M. Toyoshima, “Secrecy analysis of FSO systems considering misalignments and eavesdropper’s location,” IEEE Transactions on Communications, vol. 68, no. 12, pp. 7810–7823, 2020.
3. K. Guo, K. An, Y. Huang, and B. Zhang, “Physical layer security of multiuser satellite communication systems with channel estimation error and multiple eavesdroppers,” IEEE Access, vol. 7, pp. 96 253–96 262, 2019.
4. R. Chen, C. Li, S. Yan, R. Malaney, and J. Yuan, “Physical layer security for ultra-reliable and low-latency communications,” IEEE Wireless Communications, vol. 26, no. 5, pp. 6–11, 2019.
5. M. J. Saber and S. M. S. Sadough, “On secure free-space optical communications over Málaga turbulence channels,” IEEE Wireless Communications Letters, vol. 6, no. 2, pp. 274–277, 2017.
6. Y. Ai, A. Mathur, G. D. Verma, L. Kong, and M. Cheffena, “Comprehensive physical layer security analysis of FSO communications over Málaga channels,” IEEE Photonics Journal, vol. 12, no. 6, pp. 1–17, 2020.
7. D. R. Pattanayak, V. K. Dwivedi, V. Karwal, I. S. Ansari, H. Lei, and M.-S. Alouini, “On the physical layer security of a decode and forward based mixed FSO/RF co-operative system,” IEEE Wireless Communications Letters, vol. 9, no. 7, pp. 1031–1035, 2020.
8. X. Pan, H. Ran, G. Pan, Y. Xie, and J. Zhang, “On secrecy analysis of DF based dual hop mixed RF-FSO systems,” IEEE Access, vol. 7, pp. 66 725–66 730, 2019.

9. S. Althunibat, S. C. Tokgoz, S. Yarkan, S. L. Miller, and K. A. Qaraqe, “Physical layer security of dual-hop hybrid FSO-mmWave systems,” IEEE Access, vol. 11, pp. 58 209–58 227, 2023.
10. D. R. Pattanayak, V. K. Dwivedi, V. Karwal, P. K. Yadav, and G. Singh, “Physical layer security analysis of multi-hop hybrid RF/FSO system in presence of multiple eavesdroppers,” IEEE Photonics Journal, vol. 14, no. 6, pp. 1–12, 2022.
11. M. Alzenad, M. Z. Shakir, H. Yanikomeroglu, and M.-S. Alouini, “FSO-based vertical backhaul/fronthaul framework for 5G+ wireless networks,” IEEE Communications Magazine, vol. 56, no. 1, pp. 218–224, 2018.
12. Y. Zhang, J. Ye, G. Pan, and M.-S. Alouini, “Secrecy outage analysis for satellite-terrestrial downlink transmissions,” IEEE Wireless Communications Letters, vol. 9, no. 10, pp. 1643–1647, 2020.
13. Y. Xiao, J. Liu, Y. Shen, X. Jiang, and N. Shiratori, “Secure communication in non-geostationary orbit satellite systems: A physical layer security perspective,” IEEE Access, vol. 7, pp. 3371–3382, 2019.
14. W. Cao, Y. Zou, Z. Yang, et al., “Secrecy outage analysis of relay-user pairing for secure hybrid satellite-terrestrial networks,” IEEE Transactions on Vehicular Technology, vol. 71, no. 8, pp. 8906–8918, 2022.
15. X. Zhou, Q. Wu, S. Yan, F. Shu, and J. Li, “UAV-enabled secure communications: Joint trajectory and transmit power optimization,” IEEE Transactions on Vehicular Technology, vol. 68, no. 4, pp. 4069–4073, 2019.
16. B. Ji, Y. Li, D. Cao, C. Li, S. Mumtaz, and D. Wang, “Secrecy performance analysis of UAV assisted relay transmission for cognitive network with energy harvesting,” IEEE Transactions on Vehicular Technology, vol. 69, no. 7, pp. 7404–7415, 2020.
17. O. B. Yahia, E. Erdogan, G. K. Kurt, I. Altunbas, and H. Yanikomeroglu, “Optical satellite eavesdropping,” IEEE Transactions on Vehicular Technology, vol. 71, no. 9, pp. 10 126–10 131, 2022.
18. E. Erdogan, O. B. Yahia, G. K. Kurt, and H. Yanikomeroglu, “Optical HAPS eavesdropping in vertical heterogeneous networks,” IEEE Open Journal of Vehicular Technology, vol. 4, pp. 208–216, 2023.
19. V. Bankey, S. Sharma, S. R, and A. S. Madhukumar, “Physical layer security of HAPS-based space–air–ground-integrated network with hybrid FSO/RF communication,” IEEE Transactions on Aerospace and Electronic Systems, vol. 59, no. 4, pp. 4680–4688, 2023.
20. E. Erdogan, I. Altunbas, G. K. Kurt, M. Bellemare, G. Lamontagne, and H. Yanikomeroglu, “Site diversity in downlink optical satellite networks through ground station selection,” IEEE Access, vol. 9, pp. 31 179–31 190, 2021.
21. Prediction Methods Required for the Design of Earth-Space Telecommunication Systems, Rec. ITU-R P.1622, International Telecommunication Union, Geneva, Switzerland, 2003.
22. I. I. Kim, B. McArthur, and E. J. Korevaar, “Comparison of laser beam propagation at 785 nm and 1550 nm in fog and haze for optical wireless communications,” vol. 4214, E. J. Korevaar, Ed., pp. 26–37, 2001.
23. M. S. Awan, E. Leitgeb, B. Hillbrand, F. Nadeem, M. Khan, et al., “Cloud attenuations for free-space optical links,” in 2009 International Workshop on Satellite and Space Communications, IEEE, 2009, pp. 274–278.
24. O. B. Yahia, E. Erdogan, G. K. Kurt, I. Altunbas, and H. Yanikomeroglu, “Haps selection for hybrid RF/FSO satellite networks,” IEEE Transactions on Aerospace and Electronic Systems, vol. 58, no. 4, pp. 2855–2867, 2022.
25. S. Sabetghadam and F. Ahmadi-Givi, “Relationship of extinction coefficient, air pollution, and meteorological parameters in an urban area during 2007 to 2009,” Enviromental Science and Pollution Research, vol. 21, pp. 538–547, 2014.
26. R. Barrios and F. Dios, “Exponentiated weibull distribution family under aperture averaging for Gaussian beam waves,” Opt. Express, vol. 20, no. 12, pp. 13 055–13 064, Jun. 2012.
27. R. Barrios Porras, “Exponentiated Weibull fading channel model in free-space optical communications under atmospheric turbulence,” Ph.D. dissertation, Dept. of Signal Theory and Commun., Univ. Politècnica de Catalunya, Barcelona, 2013.
28. L. C. Andrews and R. L. Phillips, Laser Beam Propagation Through Random Media: Second Edition, 2005.
29. E. Erdogan, I. Altunbas, G. K. Kurt, and H. Yanikomeroglu, “The secrecy comparison of RF and FSO eavesdropping attacks in mixed RF-FSO relay networks,” IEEE Photonics Journal, vol. 14, no. 1, pp. 1–8, 2022.
30. W. M. R. Shakir, J. Charafeddine, H. Hamdan, I. A. Alshabeeb, N. G. Ali, and I. E. Abed, “Security-reliability tradeoff analysis for multiuser FSO communications over a generalized channel,” IEEE Access, vol. 11, pp. 53 019–53 033, 2023.
31. Impact of uplink transmission from fixed service using high altitude platform stations in the 27.5-28.35 GHz and 31-31.3 GHz bands on the Earth exploration-satellite service (passive) in the 31.3-31.8 GHz band, Rec. ITU-R F.1570-2, International Telecommunication Union, Geneva, Switzerland, 2010.
32. M. Hess, P. Koepke, and I. Schult, “Optical properties of aerosols and clouds: The software package OPAC,” Bulletin of the American Meteorological Society, vol. 79, no. 5, pp. 831–844, 1998.