Reliable way to transport data over 1-2 km distance
WiFi will do this quite easily. It's the only consumer wireless data system that gets you a few Mbps.

With a directional antenna on one end and a regular wifi device on the other, you should get a link at at about 2 km. I have tried this, with a 22 dBi antenna on one side of a valley, and my laptop on the other side, about 2 km apart.

Set the WiFi devices to use the lowest speed, 5 Mbps mode, so they don't continuously try to move up to higher speeds, then fail and move down again.

If one end is flying, you will need to aim the base station antenna... this could be automated with a GPS at both ends.