What is the current state of research on Autonomous Air Traffic Control? I am trying to get informed about Autonomous Air Traffic Control. Communication is crucial in this field. I am aware that different possibilities exist to realize it, for example: 


an ad-hoc network for aircraft-to-aircraft communication
an infrastructure-based communication system


of course infrastructure-based communication systems (meaning a geostationary satellite) include a high propagation delay. 

Anyways, I am thinking about a good solution for this problem and am currently looking for research papers in this field. I figured, maybe someone here knows some good sources already?
Do you mean air to air? Or were you thinking of a ground system? What sort of traffic density?

If the former there are a number of concepts within the big medernisation programs like US NextGen, EU SESAR, Australian OneSky or Japan's CARATS programs.

ICAO has a global roadmap running to 2040.

VHF datalink mode 2 is up and running now, higher bandwidth satcom comming (Inmarsat SB-S/ Iris). VOIP likely to have some interesting latency effects in airspaces eith high R/T loads.

Significant global safety spectrum, ITU, regulatory, standardisation and other institutional and political challenges stand before a cool tech idea.  

For spectrum look within current band allocations.

Aviation is generally incremental. Bear in mind thst your tech needs to be robust, globally portable.

If you can develop a regulstir accepted method to assure AI or ML apps then this would be a fertlle and lucrative area.