Lighter-than-air craft were the wave of the future until the Hindenburg burned up in full view of movie cameras in 1937. Now with few exceptions — like aerial coverage of football games — they seem like toys or novelties. But something is stirring in the realm of lighter-than-air. NASA and the Defense Advanced Research Projects Agency recently gave California-based Aeros $35 million to develop a 500-foot-long helium-filled airship that’s purported to carry more than 60 tons of cargo. And Google is floating Project Loon, the idea that Internet connectivity can be established on a network of balloons 12 miles up in the air.
Balloons also are being tested to lift wireless communications platforms high above areas stricken by disaster. Although balloons aren’t the only method for doing so, they have some unique characteristics that might help round out disaster response at the local level.
In a major disaster, ground-based communications systems are most likely knocked out, and in 12 hours or so, generators and backup batteries will grind to a halt. It may be days before organized disaster relief arrives, and so an emergency communications system is needed that local authorities can deploy within 12 hours and continue operating for 72 to 96 hours.
To fill that critical gap, the FCC, FEMA and others are looking at Deployable Aerial Communications Architecture (DACA) for emergency communications, hoisted above the Earth on aircraft, drones, helicopters, satellites or balloons.
But getting the equipment airborne is only the first challenge. Using DACA in real-world emergencies will require multiple coordination points to avoid a range of concerns.
One worry is potential interference with ground-based wireless systems that may still be operating after a disaster, or that are brought back into service following the disruption. Gregg Riddle, former president of the Association of Public-Safety Communications Officials (APCO International), for example, last year applauded an FCC inquiry into the technology as a first step toward “identifying whether and how DACA can be used … without creating interference to other emergency radio communications.” Avoiding interference will require coordination with the National Telecommunications and Information Administration (NTIA), which regulates radio spectrum.
The FAA will be involved to prevent collisions between balloons or drones carrying communications gear and other aircraft. In addition, areas near Canada or Mexico need coordination with the U.S. State Department, if operations, aerial equipment or spectrum use might impact a neighboring country.
So just how well would a balloon-based communications system work, and could local authorities launch and manage it? To find out, Reston, Va.-based Oceus Networks and two of its partners — Space Data Corp. of Chandler, Ariz., and NTIA Public Safety Communications Research of Boulder, Colo. — conducted a test in July in Adams County, Colo., one of the first areas to pilot FirstNet, a nationwide public safety wireless network. The test temporarily used FirstNet bandwidth to avoid interference issues and a special “steerable” balloon package.
What’s a ‘Steerable’ Balloon?
Balloons have their limitations. Weather balloons fly at relatively low altitudes and drift out of range, requiring periodic launches to sustain communications with the target area. Balloons can also be tethered, but at such low altitudes, area coverage is restricted. For the Adams County test, a series of hydrogen-filled high-altitude balloons provided a lift into the stratosphere, which at moderate latitudes ranges between 30,000 and 160,000 feet high. The “steerable” part includes technology that lets the balloon drop sand to ascend and vent gas to descend. Up and down is good enough to catch a ride with the wind. For the test, Space Data provided meteorological support.
“I was really impressed at how well the guys could pilot the balloon,” said Jim Patterson, vice president of Oceus Networks Public Federal Solutions. The day of the test, the jetstream was blowing about 120 mph toward Denver, which caused the balloon to move toward that city, he said. But once the balloon reached 50,000 feet, a 6 mph breeze pulled it back toward Boulder, near Adams County.
“They targeted the recovery point very early on in our launch, and they hit it exactly,” Patterson said. “Potentially you can kind of orbit over an area.” The higher the altitude, the greater the coverage area. At 75,000 feet, the area targeted for coverage was about 38 square miles.
Payload and Hardware
According to Doug Sharp, Oceus Networks’ director of engineering, the communications gear carried by the balloon is developmental. “At this point, there are not a lot of commercial payloads rated for that altitude,” he said. The test payload weighed about 50 pounds and consisted of a full 4G long term evolution (LTE) network in a box, or “network on wheels” minus the wheels.
“It was a full, self-contained deployable network that we flew on the balloon,” Sharp said. (Specifically it was a 20-watt LTE 10 megahertz Y frequency division duplex carrier in Band 14, according to Sharp.)
For the test, the team wanted to use traditional on-the-ground equipment, which included Motorola Solutions’ dongle for access to the public safety LTE network, a modem that’s designed for use in vehicles and an LTE-enabled smartphone. Tests were conducted using the different devices. “All communicated to the balloon, but it’s not limited to those,” Sharp said. “Any Band 14-certified device could be utilized.”
Down to Earth
Do first responders think public safety communications via a balloon is more than hot air? Bill Schrier, who was involved in the development of FirstNet and now works for the Washington state CIO, articulated some concerns about balloon-based communications, including vulnerability to wind currents that accompany hurricanes, tornadoes and windstorms. He added that covering such a large area on the ground would mean hundreds or thousands of responders would all share the same bandwidth and signal. In addition, connecting the transmission equipment in the balloon to the Internet — known as backhaul — would rule out fiber and make microwave transmission difficult.
Sharp acknowledged that there are still issues to hash out before real-world deployment, but he said the test confirmed that communications from a high-altitude platform could cover extended distances.
Sharp said that focusing the LTE coverage area would be important to avoid saturating the bandwidth and there are some backhaul options that weren’t included in the first test phases, such as a dedicated microwave backhaul using steerable high-gain antennas or even Wi-Fi or WiMAX technology.
“A second possibility is to utilize the newly standardized feature of LTE for in-band backhaul,” said Sharp. “This would result in reduced user-to-user throughput, but would facilitate simpler backhaul configurations.”
What Did We Learn?
One thing the team learned was not to launch a high-altitude balloon on July 2. “We launched this on World UFO Day,” Sharp said. “And the switchboard lit up, as I’m sure it did at the police station. Our balloon payload was 75,000 feet above Denver and people could see it from the ground.”
Other lessons learned included the effects of cold, thin air and low pressure on electronics, which are being applied to future platforms, Sharp said.
“We were able to close the link from the ground to the air and at various distances run data rates of anywhere from 5 megabits per second to 20 megabits on the downlink to the local stations, and we were able to close the link and communicate with the payload. We are still looking at do we have enough data to tell us about the overlap to public safety communications.”
Although the test used a balloon, emergency communications gear can just as easily be lifted by helicopter or other means. The real value, Patterson said, is what you can do with the bandwidth. “People can wear biobelts so you can keep track of where they are, beam video back and forth, give real-time situational awareness with whiteboarding and exit routes. It’s a very flexible, dynamic technology. We just tried one of the hardest-use cases for our experiment.”