As indicated in TR 22.891, the propagation delay is limited by physics, i.e. the speed of light (299 792 458 meters per second) in air and 2/3 of the speed of light in fibre connection. With these limits, 1ms one way transmission latency can be mapped to 300 km air propagation or 200 km for fibre based transmission.
When the distance between 2 sites increases (several thousands of kilometres), the difference in latency between air and optical fibre transmission media may become critical for such applications and hence it is worth considering alternative network options compared to optical fibre based network.
A constellation of Low-Earth orbiting satellites, where each spacecraft is equipped with a gNB and interconnected with other neighbouring spacecraft's via Inter Satellite Links, provides access to UEs. Such a type of constellation system would provide an overlay mesh network for users that have a need for long distance connectivity with improved latency performance or specific end to end security.
The constellation of satellites can be considered as contributing to a single overlay 5G system, or as contributing a many 5G systems as many countries covered by the Constellations for instance.
Global organisations with distributed sites around the world may require long distance connectivity between the sites with critical requirements including low latency, reliability and/or end-to-end security to support critical application domains such as High Frequency Trading (HFT), Banking or Corporate communications.
An organisation is structured on a set of distributed sites throughout the globe that needs to be interconnected. This organisation has strong requirements with respect to security as well as with respect to Quality of Service (QoS), both for bandwidth and latency, since operations are related to these metrics: for mining or oil & gas exploitation, for trading, etc. The case of High Frequency Trading is addressed here.