An unmanned airplane that continues to fly through the stratular area becomes a base station, and the future is approaching, delivering radio waves to mobile devices.In April 2019, SoftBank Co., Ltd. has developed the HAPS (High Altitude Platform Station) business through a subsidiary HAPS Mobile Co., Ltd..With the cooperation of), it has been announced that it has developed an unmanned aircraft "HAWK30 (Hawk 30)" for stratular communication platforms that can fly in a stratified area of about 20 kilometers above the ground.
In August this month, we will explain the HAPS, a notable technology that continues to progress steadily for practical use, such as announcing the acquisition of flight permission from the unmanned aircraft "HAWK30" in Lanai Island, Hawaii.
Many people have seen antennas in various places, such as the roof of the building and the tower.Many base station antennas installed for mobile phone services are installed in such a high position to deliver radio waves to a wide range.In addition, one of the reasons for radio waves may be difficult to reach between the base station antenna and the mobile terminal, which may be difficult for radio waves to reach, and many tower -type ground base stations areAn antenna is installed at about 40-50m above ground.
The higher the tower, the more the range that can be covered by one base station expands, and the more you are affected by obstacles.However, there is a limit to raising the tower.The height of the building is the same.That's where HAPS, a technology that provides communication from the sky by an airplane with a base station, appears.
According to the current technology, it is said that the range that general base stations can communicate is about 100 km in a straight line, so if you prepare one base station about 20 km from the ground, one base station.It is an area where the radius of about 100 km and 200 km in diameter can be communicated.Therefore, it requires thousands and tens of thousands of base stations to cover the entire Japanese archipelago at the ground base station, while HAWK30 can cover the entire Japanese archipelago with about 40 aircraft.
There are other benefits.The cover range is very large, so you can significantly reduce the out -of -area area.It is possible to communicate even in places where ground base stations such as mountainous and remote islands are difficult to deal with, and build a stable Internet connection environment in places and regions where communication networks such as developing countries are not developed.It will be possible.It can also be expected to be a countermeasure in the event that a disaster such as an earthquake has occurred and the ground base station cannot be operated due to damage.
Furthermore, base stations in the strat cannot be compatible with flights such as drones, which are higher than ground base stations.
Suddenly, "Do you know the speed of radio waves transmitted?"
If you ask this question, you may be lost in the answer, but I think many people can answer at the speed of light (about 300 million meters per second = 3 seconds per second..0×108m/s）。なぜこの話をしたかというと、光も電波も同じ電磁波の一種であり、その速さは有限です。実はこれが、非常に重要なポイントなのです。
From the perspective of "radio waves from the sky (viewed from the ground)", it is thought that communication with satellites in outer space is similar.The difference is the distance.
For example, Geostationary Earth Orbit / Geo Satellite is about 36,000 km from the ground and about 1200 km away from the ground, about 36,000 km (Low Earth Orbit Satellite / Leo Satellite).For the ground orbital satellite, about 36,000 km away from the ground, you need a 200 msec time (milliseconds) with only one -way communication.RTT takes at least 400msec, at least, because it takes the same time to receive a reply.The low orbit circular satellite is about 9 msec only in one direction, which will affect the calling call by mobile phone.However, if it is a HAPS that uses a stratastic area of about 20 km from the ground, 0 in one direction.It only takes 3msec.
In terms of power density, the use of stratastic spines is dominant.Radio waves are transmitted without declining power density in free spaces (ideal space without material), but in reality they weaken as the distance becomes long (attenuation in proportion to the two square of the distance).
As the power density is weakened, the communication quality deteriorates (it may be easier to imagine the smartphone antenna bar).The HAPS power density, which is short from the ground, is about 1 million times that of the track satellite on the ground and about 10,000 times the low orbit circular satellite, and can provide high -quality communication services for existing mobile devices.。
And the environment in the stratastic area is also a major factor.Because it is higher than the clouds, solar panels can always receive sunlight, and because the wind is relatively calm throughout the year, you can fly for a long period of several months, and a base station by unmanned airplane.It is a very attractive environment to operate.