How it works?
The project uses high-altitude balloons placed in the stratosphere at an altitude of about 18 km (11 mi) to create an aerial wireless network with up to 4G-LTE speeds.
The movement of those balloons is done by adjusting their altitude in the stratosphere to float to a wind layer after identifying the wind layer with the desired speed and direction using wind data from the National Oceanic and Atmospheric Administration (NOAA).
Stratospheric layer: Google asserts that this particular layer of the stratosphere is advantageous because of its relatively low wind speeds (e.g., wind speeds between 5 and 20 mph / 10 to 30 km/h) and minimal turbulence. Moreover, Google claims that it can model, with reasonable accuracy, the seasonal, longitudinal, and latitudinal variations in wind speeds within the 18–25 km stratospheric layer. So that it can control the latitudinal and longitudinal position of high-altitude balloons by adjusting only the balloon’s altitude.
Gases in balloons: By adjusting the volume and density of the gas (e.g., helium, hydrogen, or another lighter-than-air compound) in the balloon, the balloon’s variable buoyancy system is able to control the balloon’s altitude. Google has additionally indicated that balloons may be constructed from various materials (e.g., metalized Mylar or BoPET) or a highly flexible latex or rubber material (e.g., chloroprene).
Users of the service connect to the balloon network using a special Internet antenna called patch antenna(it is a directional antenna which transmits a signal to ground users or LTE users) attached to their building. The signal travels through the balloon network from the balloon to balloon, then to a ground-based station connected to an Internet service provider (ISP), then onto the global Internet.
Balloon to balloon communication: Initially, the balloons communicated using unlicensed 2.4 and 5.8 GHz ISM bands, and Google claims that the setup allows it to deliver “speeds comparable to 3G” to users
How balloons are made?
- Balloons are composed of polyethylene plastic about 0.076 mm (0.0030 in) thick. The balloons are super pressure balloons filled with helium, standing 15 m across and 12 m tall when fully inflated.
- Balloons carry a custom air pump system dubbed the “Croce” that pumps in or releases air to ballast the balloon and control its elevation.
- Balloons have a 10kg box contains circuit boards that control the system, radio antennas and a Ubiquiti Networks ‘Rocket M2’ to communicate with other balloons and with Internet antennas on the ground, and batteries to store solar power so the balloons can operate during the night.
- A parachute attached to the top of the envelope allows for a controlled descent and landing when a balloon is ready to be taken out of service.
- The balloons are equipped with automatic dependent surveillance-broadcast and so can be publicly tracked.