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How 5G is pushing the envelope on latencyHow 5G is pushing the envelope on latency

The proprietary wireless network used by the Drone Racing League supports latency of 5 ms. Top 5G companies are looking to eventually match that.

Mike Dano

December 22, 2020

5 Min Read
How 5G is pushing the envelope on latency

Some of the world's most advanced technology companies are in the early stages of pushing the speed of 5G latency beyond the realm of human perception.

To do so, they're employing some pretty cool toys.

Qualcomm, Ericsson and T-Mobile are investigating how speedy 5G connections might be used to pilot remote control cars and drones. Their goal is to prove that 5G technologies are fast enough to make pilots feel like they're actually sitting inside the toys they're steering.

What they're targeting is latency – the time it takes for a drone to send a video of what it sees to the virtual reality goggles being worn by its pilot, and then the time it takes for that pilot's reactions to be sent back to the drone. Such calculations are measured in milliseconds. [Ed. note: To our American readers – there are 1,000 milliseconds (ms) in every 1 second.]

"Our Racer4 drones feed a live standard definition [video] signal back to the pilots' FPV [first person view] goggles with less than 5 milliseconds of latency," wrote Ashley Ellefson, the COO of the Drone Racing League (DRL), in response to questions from Light Reading. "Cameras on the drones have a fixed angle for the flight, ensuring the pilot will see a real-time image of the course directly in front of the drone."

5G drones

The DRL is a sport enabled by – and celebrating – technology. It uses a proprietary wireless network to connect custom drones to their pilots. "In racing, pilots must make split-second reactions to what they see in their goggles, so it's very important that there is near-zero latency between the images they are seeing from the video feed in their goggles, the inputs into the controller, and the response of the drone as it travels through neon-bright obstacles at up to 90 mph and we designed our RF [radio frequency] network to support exactly this," Ellefson wrote, explaining that the DRL has conducted dozens of drone races in iconic locations like museums and palaces all over the world.

Ericsson calculated that a latency of 50 ms would mean the difference of almost 6 feet of additional travel for a drone flying at 80 mph.

"Our radio technology allows us to design complex, three-dimensional drone racing courses that can stretch a mile-long and weave through concrete while enabling our elite drone pilots to compete at the highest level," Ellefson explained.

Thus, it's no surprise that T-Mobile recently invested in DRL through its new T-Mobile Ventures investment arm. The company didn't disclose the amount of the investment, but one of the goals is to eventually get the DRL to add 5G drones into its tournaments.

"We're excited to partner with T-Mobile to custom-build new racing drones powered by T-Mobile 5G in 2021. These drones will enable high definition-video streaming to create new immersive first-person viewing opportunities and experiences for the tens of millions of DRL fans and T-Mobile customers," Ellefson wrote. "While we are still in the early stages of development and have not announced plans around transitioning our racing to a 5G network, our aim is to one day integrate 5G-powered racing drones into our sport."

That's likely also the end goal of Ericsson and Qualcomm, which recently teamed to show off a private 5G network using edge computing and running in millimeter-wave spectrum controlling a remote control race car transmitting video via Qualcomm's latest smartphone processor.

RC hobbyists and multi-purpose technology

In a lengthy and highly detailed post to the company's website, Ericsson's Attila Takacs wrote that the infrastructure vendor managed to reduce overall latency in a remote control (RC) race car setup to around 20-25 ms.

Interestingly, Takacs explained that human reaction time is typically around 200-250 ms and that the fastest a human can process and understand visual information is around 15 ms.

"From this, we can summarize that latency below 15 ms does not affect human performance, whereas anything above 100 ms will begin to negatively impact the performance noticeably," he wrote. "Somewhere in between, say around 50 ms is an ideal balance in terms of stressing technological limits and achieving close to optimal human performance in fast-paced real-time settings."

Takacs added that, when using "digital video streaming with low-cost components, we can achieve around 85ms average loop latency. While this is inferior to the analog video of RC systems, it is already below the 100ms real-time 'usability' limit."

And that's important, he explained, considering RC hobby products "are purpose-built for the one thing: low-latency control and first-person-view (FPV) video for local operation. 5G, in contrast, is a multi-purpose technology for nationwide deployments. RC racing is a worthy challenger of 5G's flexibility."

Commercial 5G networks in the US are nowhere near these blistering latency speeds. For example, a recent RootMetrics test of T-Mobile's 5G network in Los Angeles found latency speeds around 76 ms. But other 5G carriers around the world are clocking much lower figures: For example, RootMetrics found that LG U+ in South Korea registered a latency speed of just 22 ms.

About the Author(s)

Mike Dano

Editorial Director, 5G & Mobile Strategies

Mike Dano is Light Reading's Editorial Director, 5G & Mobile Strategies. He has covered the wireless industry as a journalist for almost two decades, first at RCR Wireless News and then at FierceWireless and recalls once writing a story about the transition from black and white to color screens on cell phones. Mike is based in Denver and can be reached at [email protected]. Follow @mikeddano on Twitter and find him on LinkedIn.

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