Perhaps Facebook Co-Founder and CEO Mark Zuckerberg is just a wee bit excited about the Connectivity Lab, the initiative aimed at using high-altitude long-endurance planes, satellites, and lasers to help connect the rest of the world to the Internet. Zuckerberg followed up Thursday’s announcement on the Internet.org site, as well as his own post on Facebook, with a lengthy post (embedded below) offering a more detailed look at Connectivity Lab.
Highlights from “Connecting the World from the Sky” include:
Our research has shown that approximately 80 percent to 90 percent of the world’s population lives today in areas already covered by 2G or 3G networks. These environments are mostly urban or semi-urban, and the basic cell and fiber infrastructure has already been constructed here by mobile operators. For most people, the obstacles to getting online are primarily economic.
For the remaining 10 percent to 20 percent, the economic challenges also apply, but in this case they also explain why the basic network infrastructure has yet to be built out. The parts of the world without access to 2G or 3G signals are often some of the most remote places on Earth, where physical access to communities is difficult. Deploying the same infrastructure here that is already found in urban environments is uneconomical, as well as impractical.
But deploying the same infrastructure solutions for everyone is also unnecessary when we consider the different population densities found in different communities. In dense urban areas, greater network capacity is needed to serve a larger population. That means we need to build cell towers, small cells, or a big network of Wi-Fi access points.
But in the less urban and less connected markets, there are also fewer people distributed over a wider area. Deploying other infrastructure solutions like satellites might be more efficient and cost effective. Our strategy is to develop different types of platforms to serve different population densities.
Before discussing the relative costs, benefits, and capabilities of these platforms, it’s important to understand the fundamental constraints we need to consider while working on aerial connectivity. These are not only issues of cost, efficiency, and deployment, but also the basic laws of physics.
The most important constraint to consider is that as you increase altitude, assuming all else is equal, the signals emitted by aerial platforms cover a wider area and, therefore, become weaker. More specifically, the power of a radio signal weakens as a square of distance.
If you consider cell towers, they can provide really strong signals across relatively small areas. And stronger signals create the ability to deliver higher capacity. A plane at an altitude of 20 kilometers will allow you to reach people more than 100 kilometers away, but the signal loss will be significantly higher than would occur for terrestrial networks. And if you send up a satellite that can beam Internet across an entire continent, it might have wide reach across a large territory, but its signal will be a lot weaker than almost any other option for connecting.
Boosting the signal in order to achieve a high bandwidth capacity is also very impractical. Radio signals get weak very quickly, so they require a large amount of power to strengthen. Since satellites generally rely on solar power as their energy source, generating a lot of power (would need to square to make up the difference) would mean constructing either huge, unstable structures, which are impractical, or nuclear powered satellites, which are very expensive.
FSO (free-space optical communication) is a promising technology that potentially allows us to dramatically boost the speed of Internet connections provided by any of the previously mentioned platforms. The lasers used in FSO systems provide extremely high bandwidths and capacity, on par with terrestrial fiber-optic networks, but they also consume much less power than microwave systems. Because you can make the beam so much narrower, this allows you to focus all of your power exactly where you want it to go.
Using FSO technology could boost the signals being sent from Earth to orbit, and then between satellites in an orbital constellation. Potentially, the same system can also dramatically increase the speed of Internet connections on the ground that are provided by satellite. If a laser receiver is mounted at a destination, a laser-equipped satellite can transmit data to it.
Using FSO to connect people on the ground would dramatically increase the utility of satellites in providing Internet access to larger segments of unconnected populations.
At the same time, FSO has a number of significant weaknesses. The narrow optical beams are hard to orient correctly and need to be pointed very precisely. The level of accuracy required is the equivalent of needing to hit a dime from 10 miles away, or hit the Statue of Liberty from California. Laser systems also require line of sight between both ends of the laser link, meaning that they don’t work through clouds and are very vulnerable to bad weather conditions. As a result, backup radio systems are needed.
Despite these weaknesses, if we can overcome these problems, FSO can provide ways to connect people that are a lot better and more cost-effective. We’ve already started hiring world experts on FSO, and we’re going to invest in exploring the full potential of this technology over the coming years.
High-altitude drones are one major area we’re focused on developing. To understand the reasons for this, it is helpful to consider some of our technical constraints.
We want to:
- Fly as close to the ground as possible in order to maximize signal strength.
- Fly at a high enough altitude where the wind is not very strong in order to maximize endurance.
- Fly outside of regulated airspace for safety and quick deployment.
- Be able to precisely control the location of these aircraft, unlike balloons.
- Build the smallest structure possible so it requires minimal energy to stay aloft.
- Build a large enough structure that can effectively harvest all the energy it needs from the sun.
- Build the cheapest structure so we can cost effectively produce enough to span many areas.
- Build a reusable structure to make it more cost effective, as well.
Based on these constraints, drones operating at 65,000 feet are ideal. At this altitude, a drone can broadcast a powerful signal that covers a city-sized area of territory with a medium population density. This is also close to the lowest altitude for unregulated airspace, and a layer in the atmosphere that has very stable weather conditions and low wind speeds. This means an aircraft can easily cruise and conserve power, while generating power through its solar panels during the day to store in its batteries for overnight use.
With the efficiency and endurance of high altitude drones, it’s even possible that aircraft could remain aloft for months or years. This means drones have more endurance than balloons, while also being able to have their location precisely controlled. And unlike satellites, drones won’t burn up in the atmosphere when their mission is complete. Instead, they can be easily returned to Earth for maintenance and redeployment.
Readers: Do you think Facebook and Internet.org will succeed in their mission to bring connectivity to everyone on Earth?