Facebook managed to transmit data at nearly 20 Gbps between two towers in Southern California as part of testing a technology key to its plans to provide internet service to rural areas using drones.
The tests were conducted earlier this year and used frequencies in the E-band, a group of millimeter wave frequencies between 60 and 90 GHz.
Such signals are capable of transmitting data at high bandwidth, but are susceptible to being attenuated by distance, weather conditions and obstacles. They are therefore generally used for short-range point-to-point transmissions.
Facebook used a two-foot-long satellite dish to send data over an eight-mile link between Malibu and Woodland Hills.
This test initially recorded data between 100 Mbps and 3 Gbps and allowed engineers to collect transmission data on clear days and during clouds, fog, high winds and rain, Facebook said in a statement. Thursday blog post.
For testing, Facebook ended up integrating several of its own microwave transmission components into the system, which used a 1.2-meter dish at the receiving end.
The signal received by the dish would halve if it was misdirected by just 0.2 degrees, so accuracy was essential.
To achieve a data rate of up to 20 Gbps, the dish had to be near perfect: an accuracy of over 0.07 degrees. In perspective, that’s the equivalent of a baseball pitcher hitting a quarterback, Facebook said.
The distance reached is important and already useful for point-to-point links that could transmit high-speed Internet signals over land.
But it’s not far enough away to be used as a backbone for the company’s planned drone internet service.
Facebook’s Aquila drones will provide Internet access to remote areas at altitudes between 60,000 and 90,000 feet, or approximately 18 to 27 kilometers. Since the drones will not always be over the ground station, the link distance could be longer.
For the drone service, Facebook will need to increase the range to 30 to 50 kilometers and increase the bandwidth to 30 Gbps, the company said.
The next step in testing in California is a ground-to-air system that will transmit data to a Cessna aircraft with a data transceiver on board.
Testing of a system capable of pulling a 20 Gbps data link to the aircraft at an altitude of up to 20,000 feet (six kilometers) has already begun. In 2017, Facebook plans to increase the speed to 40 Gbps both to and from the aircraft.
âWe still have several connectivity and technical issues to resolve before the technology is fully ready for deployment,â Facebook said.
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