Facebook’s Connectivity Lab now is flight testing its first generation air-to-ground bidirectional link capable of 20 Gbps in each direction, intended to support the Aquila unmanned aerial vehicle for internet backhaul.

The aerial payload is mounted on a Cessna aircraft and is being flown at altitudes up to 20,000 ft., Facebook says.

The next generation air-to-ground communication system capable of supporting 40 Gbps each on uplink and downlink between an aircraft and a ground station will be flight-tested in early 2017.

Earlier in 2016 Facebook tested a terrestrial point-to-point link in Southern California.

In that test the link achieved a data rate of nearly 20 Gbps over 13 km at millimeter frequencies.

Using a set of custom-built components, the team achieved that data rate using 105 watts of total direct current (DC) power consumption at the transmitter and receiver.

The transmission used a bandwidth of 2 GHz, resulting in an overall spectral efficiency of 9.8 bits per second per Hertz.