The idea of using the stratosphere for improving communications was introduced and tested almost a decade ago. The European project Capaninia developed wireless and broadband technologies for use on high altitude platforms (HAP) floating at an altitude around 20 km. HAPs float above aircrafts, but below satellites. Thus, they do not interfere with any device. The main purpose was to provide low cost communications to remote areas.
Some days ago Google announced its Loon project. Project Loon is a network of balloons that will provide internet and communications to rural and remote areas. The project will fill coverage gaps and bring people back online after disasters. The balloon-balloon and balloon-ground communication are be obtained through radio frequency using ISM bands between 2.4 and 5.8 GHz. Each balloon can provide service to an area up to 40 km diameter, with a speed equivalent to 3G (Image 1).
Image 1. Baloon-balloon and balloon-ground communication
Image Source: Project Loon
How it works?
The balloons are made of polyethylene plastic sheets. Once fully inflated, they are 15 m wide and 12 m high. Each unit is powered by solar panels able to produce up to 100 Watts. Besides, the panels also charge a battery for night use; hence, each unit is able to work the whole day by using only renewable energy.
Each unit also has a box containing the circuit boards that control the system, batteries to operate at night, radio antennas to communicate with other balloons, and the internet antennas to provide the service.
Project Loon takes advantage of the fact that winds in the stratosphere are usually steady and slow, with velocities between 5 and 20 mph. Besides, it is stratified in layers with different wind direction and wind magnitude. Thus, dedicated algorithms determine the required direction of the balloon, so that the balloon will move to the layer with the required wind (Image 2).
Image 2. Balloons navigation according to the wind
Image Source: Project Loon
The following video (Animation 1) summarizes the project and its functioning.
Animation 1. Project Loon
Source: Project Loon
References & Further Reading
Google experiments with internet-bearing baloons
Google's loon project put balloon technology in spotligth
Stratospheric broadbans
The Loon project