How to build a docking ring.

[SpaceTime]

Okay and here's the official (vanilla) answer brought to you by the vets™.

120 A.S.
Valhalla Research introduces their newest technological wonder, incorporating recently discovered superstrong crystalline polymers and frictionless bearings; when connected to orbital docking rings, these materials can be used to create "elevators" that almost completely negate the cost of boosting men or materials out of a planetary gravity well. Exploration and industry are revolutionzed almost overnight, opening up the entire New York system for commercial exploitation. Valhalla licenses the technology to the other houses, reaping huge returns in the process.

For the record, modern day Valhalla Research is Ageira Technologies. This technology almost certainly came from the alien civilization which created the nomads.

In sharp contrast, Gallia's docking rings are different and use powerful magnets/magnetic fields instead. Though devs never provided further insight on how they work.