India has brought out best set of drone regulations on the basis of No Permission No Take-off (NPNT). But how can the ATC establish contact with so many drones that will be unpredictably asking for take off. Also how can they be monitered through a controlled airspace? Will it be miNiaturr ADSBs fixed or something else?
I'm not sure about everywhere but in the U.S. there is an app called "Airmap" Link to webpage. It's built for commercial drone operators but it can also be used by people flying for fun.
There is a flight plan portion of the app that allows you to file for a flight. You specify time of takeoff, radius you'll fly in, altitude and aircraft. This is then submitted for approval from the FAA.
It takes a matter of seconds and your approved, or not depending on the situation. It also has a map portion that displays the other approved flight plans in the area, if the pilot made his public, so you could even use this to join other's flying at the park if you see a flight pop up or something like that.
This could be a viable answer for India as well, coupled with a mini ADS-B, like CrossRoads mentioned, could prove even better.
ADS-B Out units are getting pretty small for reporting position. Example from uAvionix.com: https://uavionix.com/products/ping1090/
Requesting takeoff clearance could be done via an automated system, where the operator enters takeoff time, time enroute, planned route, etc. Enter it some minimum number hours ahead of time for review and approval.
I am not familiar with the Indian system, however, it may be useful to discuss the US system, which is fundamental for future development.
First, the FAA has instituted a UAS Data Exchange provides for data exchange between FAA and industry partners. LAANC (Low Altitude Authorization and Notification Capability) provides near real-time data exchange. Private industry partners, there are several approved thus far, have interfaces to users, which accept the user's flight plan, and routes it to ATC for authorization. Made more efficient by predetermined grid maps near airports, etc. the FAA can rapidly approve requests without substantial interference determinations. (Table lookups, versus separation calculations.) The industry partner routes the approval back to the end user.
In addition, the industry partner makes available WX, NOTAMS, etc. through a user app.
If the operation of this system were modified, it is conceivable that there could be a UAS hold until a clearance is received. Fortunately, that has not happened. UAS are utilized at locations where there is limited communications (cellphone data) availability, and that lack of communications would impair UAS operations in those areas. And areas away from airports and some airspace will not require the explicit coordination that LAANC offers. In urban areas, or more specifically, areas near airports and restricted airspace, there is greater availability of communication, which makes LAANC more easily implementable.
At this time, LAANC covers about 500 US airports, and there is a manual process for areas not covered. There are about 14 industry providers, although only a few effectively offer services to individuals. An example is AirMap.
With respect to the issue of utilizing ADSB and similar technologies, while that may be useful, one objective of UAS traffic management is to segregate UAS and conventional aircraft. The enforcement of that segregation could be affected by utilizing downloadable, per flight, boundaries to the UAS, so that it is effectively rendered incapable of flying outside a clearance limit.
Real-time ATC monitoring of ADSB would cause capacity issues, as well as impose communications requirements to the UAS pilot. A far easier approach is to pre-clear operations and relies on the UAS to comply with an advance clearance, as well as the intrinsic separation of UAS and conventional aircraft.
Hopefully, this provides some insight as to how a prior to taking off system could be implemented, leveraging existing FAA facilities. I do not know any specifics of the implementation of regulations for India.