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will start after that’s done, said Williams. The big question, however, is spectrum management. “Who’s going to… assign those channels to users,” the ex-FAA chief noted. “There really isn’t enough spectrum to pass out to all users and take all comers.” An industry consortium or a government process must be put in place, and that’s when “a non-traditional approach” may be needed, observed Williams. “The traditional approach would take 10 years to get through this, and this is where the industry push is necessary so that they can start taking advantage of the spectrum.” Compete with Wi-Fi? As much as a dedicated drone communication spectrum makes sense, the 5GHz spectrum currently can’t be accessed by Wi-Fi chips. According to Williams, new drone spectrum wouldn’t compete with Wi-Fi, because this is an “unused, clean band.” But Parrot’s Levy pointed noted that this isn’t exactly good news for drone makers like Parrot who thrive on standards components used in smartphones to keep the cost down. If the FAA assigns drones to the newly dedicated spectrum, drones can no longer use widely available, cheap Wi-Fi chips. Ergo, more expensive drones, he said. During the online chat on the EE Times Radio Show, the ex- FAA drone chief reiterated why the existing cellular infrastructure is hardly ideal for drone communication. He noted, “There are many problems with using existing cellular infrastructure for controlling drones. The antennas are pointed at the ground not the sky, the technology is not set up for high speeds, some of the spectrum used is prohibited from being transmitted from an airborne transmitter, and the lack of link reliability is also a problem.” Qualcomm’s director of engineering Chad Sweet, countered: “Jim, it turns out, due to free space properties, even with the antennas pointed at the ground the problem is seeing too many towers and not too few.” Obviously, the lack of cell signal availability worries drone users. Qualcomm’s Sweet said, “As the craft goes higher in rural areas, the coverage gets better.” However, he added, “Existing networks would likely only be a stop-gap. A dedicated network would be needed longer term.” There are alternative communication methods, but they aren’t great. “A satellite transceiver is too heavy for small UAVs,” Sweet said. He opined that cellular networks might be designed for all sorts of coverage Chad Sweet scenarios. “Australia is a great example. They have sites that go for up to 100 miles.” Sweet concluded. “Cellular technology has been optimized for efficient multiple access over the last 30 years. It also has a nice property of being light weight. Regardless of spectrum chosen, leveraging cellular technology will help quickly deploy UAV to ground communications.” www.electronics-eetimes.com Electronic Engineering Times Europe September 2015 21


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