Satellite communications have garnered a lot of attention over the past decades and the discussions around them tend to include loads of current buzzwords – Internet of Things, 6G (not even 5G any more), telemedicine, self-driving cars etc. The authors of the paper aim to shed light on the current state of satellite networks, to "demystify" them and give an overview of current capabilities and possible future directions.
One clear possible path is to connect the unconnected, providing connectivity services to the parts of the earth that are currently not networked. That is particularly important for remote locations. Ultimately, the goal would be a global internet, an integrated satellite and terrestrial network providing connection to all.
The paper focuses on two use cases: firstly, the aforementioned global internet coverage, and secondly, interplanetary communication, utilising deep space satellites.
The inter-satellite and deep space network (ISDSN) is a complete ecosystem of satellites, enabling both of these use cases. The creation of such an ecosystem does not come without challenges – not just the technical ones of networking, inter-satellite links, routing and physical layer communications, but also in the matters of security. It is noted that the advent of CubeSats has brought with it new security threats, as their low-cost (both development and launch) allow for novel eavesdropping opportunities.
The authors list a three-tier structure for futuristic satellite networks:
1) Tier 1: Satellite to Ground Station
2) Tier 2: GEO/MEO/LEO inter-satellite links
3) Beyond-GEO communications
Tier 1 and its challenges is the most researched, particularly the security issues, as most classic cyberattacks could be used in this architecture. In the higher-tier networks, very specific challenges apply that need a different approach.
The paper takes a look at key management, noting that in the context of the proposed ISDSN, central management authority is very challenging due to vast geographic distances. Key management should also take into account the probable high dynamics of the network; moreover, poor line of sight might also effect bit error rates – and higher bit error rates hamper efficient key management protocol.
Secure routing also boasts good research at Tier 1 level, but less at higher tiers – and especially little considering the new threats caused by CubeSats. The authors provide some recommendations for this, e.g reducing the number of hops, adapting to the network dynamics and balancing the load among various satellites.
Classic cyberattacks, such as DDoS, similarly don't have much research at the higher-tier levels, but the mitigation is similar to Tier 1 which is well researched. The paper also notes that quantum cryptography, particularly QKD, could become useful.
Source:
Usman, M., Asghar, M.R., Ansari, I.S. and Qaraqe, M. (2021). Demystifying Futuristic Satellite Networks: Requirements, Security Threats, and Issues. In Autonomous Airborne Wireless Networks (eds M.A. Imran, Q. Abbasi, O. Onireti and S. Ansari). https://doi.org/10.1002/9781119751717.ch13
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