We are a go for launch!

Qualcomm this week unveiled the results of a months-long drone trial program, which found LTE networks today already provide the aerial connectivity necessary to support commercial unmanned aerial vehicle deployments. But the tech giant noted some network optimizations will be necessary to take drone deployments to new heights.

In a series of around 1,000 flights, Qualcomm said it tested the mobile connectivity achieved by drones at a set of low altitudes. Flight heights ranged from ground level, to 30, 60, 90, and 120 meters, and connectivity was achieved via commercial cellular networks utilizing PCS, AWS, and 700 MHz spectrum. The trial tested the viability of LTE networks for drones operating beyond visual line of sight (BVLOS), but all of Qualcomm’s test flights were performed under VLOS per their FAA authorization, Qualcomm VP of Engineering Paul Guckian said in a blog post.

Using an on-device modem and Snapdragon Navigator logs as well as IPerf logs, Qualcomm said it tracked connectivity data along the drone flight routes at different altitudes. The goal, the company said, was to quantify the downlink (DL) signal to interference plus noise ratio (SINR) distribution; study the impact of uplink (UL) power control design on network interference; and look at the difference in  handover performance between the drones compared to regular ground user equipment.

The study found the LTE signals used by the drones propagate further at altitude than they due on the ground thanks to a lack of environmental obstacles, and were quite strong despite the presence of downtilted antennas in the network. The wider propagation meant fewer handover events, and more stable signals for the drones, the team found. Overall, coverage was comparable for vehicles in the air and mobile devices on the ground, the results showed.

“One of the findings is that (drones are) ready to be up and running commercially. It would naturally be an evolution of the number of drones you would see … but in somewhat limited numbers, drones are ready to be on the network,” the trial’s lead engineer Harris Teague said. “But if you want to go out and scale this to large numbers we see potential for optimizing networks for that use. Carriers, of course, have a very strong interest and need to protect the performance of their networks. So we’re working closely with them to help make sure that happens so network performance does not become a barrier to scaling of these kinds of uses.”

To support wide-scale operation of drones, the study recommended a number of interference mitigation techniques, including implementation of an optimized Open-Loop Power Control approach and serving cell selection optimization.

Qualcomm said it plans to pass along its findings to the 3GPP standards body, which in March approved a study item to optimize LTE performance for low-altitude aerial vehicles. The company also plans to share its study with the Drone Advisory Committee Sub-Committee (DAC-SC) and the FAA. Teague said field testing at Qualcomm will continue to gather more data.