UAV base stations are expected to become a flexible, reliable endurance communication base station, especially as an emergency solution for typhoons, landslides, earthquake natural disasters, and extreme conditions. The author of this article will take you into the world of drones and explore the truth of drone technology.

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The 5G base stations for drones
UAV base stations are expected to become a flexible, reliable endurance communication base
station, especially as an emergency solution for typhoons, landslides, earthquake natural
disasters, and extreme conditions. The author of this article will take you into the world of drones
and explore the truth of drone technology.
Antenna height is the main factor affecting the coverage of wireless communication. Raising the
antenna can reduce the influence of terrain on radio wave propagation. It can even change
over-the-horizon communication to line-of-sight communication, which significantly improves
the quality of communication links. Utilizing the unmanned aerial vehicle to carry the
communication load to lift off to improve the communication problems caused by the terrain,
ground objects and the curvature of the earth has gradually become a research and application
hotspot at home and abroad.
UAV relay communication has started very early and is limited by the drone's flight carrying
capacity, air time, and other factors. UAV relay communication mainly uses large and
medium-sized fixed-wing drones and unmanned helicopters as the communication platform.
The principle of the Loon project to achieve high-altitude communication
Well-known aerial network base station projects mainly include Google's Loon (submerged bird
plan, ascent to the stratosphere through a hot air balloon, 100-180 days of life) and Facebook's
Aquila (Sky Eagle plan, using drones to carry out Laser communications, 90-day battery life); and
near-Earth satellite communications solutions from SpaceX, OneWeb, and more. The purpose of
such airbase stations is to achieve wide-area signal coverage and solve the problem of lack of
infrastructure in remote areas to expand network service audiences.
Google Loon: The Flying Helium Balloons
Loon can be said to be a very simple and rude project. At first, the project developers hung a
router (signal relay device) on a weather balloon, let it fly to a height of 10 kilometers, and then
saw if there was a signal.
After continuous evolution, the helium balloon has a sealable structure and a modular aluminum
load, as well as solar cells, fuel cells, and some electronic components, enabling it to maintain
long-term flight under conditions of varying temperature differences and high-intensity
ultraviolet radiation, And use algorithms to direct the power and thermal systems to change the
balloon position and adjust the population of the balloon group. It is reported that the Loon
project has conducted flight tests in New Zealand, Sri Lanka, Australia, Indonesia, and other
places.
Facebook Aquila: Boeing 737 wingspan
In 2014, Facebook acquired British airline Ascenta to prepare for drone manufacturing and laser
communications. Subsequently, Zuckerberg announced the Skyhawk plan to use drones as a
carrier to use laser communications to achieve two-thirds of the world's wireless coverage.
It is reported that Aquila plans to upgrade from a helium balloon to a stratosphere with stable
climate and environment, flying at 90,000 feet during the day, avoiding commercial aircraft
routes, absorbing and storing solar energy, and flying at 60,000 feet at night, with a target battery

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life of 90 days at a time. Aquila will fly in a circular aerial area with a radius of about 3 kilometers,
and Facebook's California laboratory engineers hope that its laser signal will cover a ground area
with a radius of about 50 kilometers.
According to recent media reports of Aquila's second test flight: the altitude rose from the first
655 meters to about 914 meters, and the time was extended by 10 minutes to 1 hour and 46
minutes.
As for the low-orbit satellite group, in November last year, SpaceX requested the FCC to launch
4,425 satellites using the reusable Falcon 9 rocket to provide high-speed Internet worldwide.
However, due to the excessive number of planned satellites, the FCC plan is still under review.
Instead, startup OneWeb, which has the support of Qualcomm, Virgin, and SoftBank, plans to
launch 720 low-orbit satellites by 2019 and is allowed by the FCC to enter the US market.
The above communication platforms are often difficult in actual promotion, mainly because:
1. Strong load capacity, high flight altitude, long-distance, and relatively long working time in the
air.
2.Large volume, complex ground support system, complex maintenance, high maintenance cost,
and high training support requirements;
3. The launch recovery conditions are high, and special landing and landing sites are required;
4. Insufficient flexibility leads to short overall dead time;
5. A coordinate flight airspace is required.
Tethered drones: 24/7 ultra-flexible
From the perspective of demand, the domestic base station construction is relatively complete,
but because of its vast size, complex geographical and climatic conditions, it is one of the
countries most severely affected by natural disasters in the world. Damage to optical fibers and
base stations caused by natural disasters can disrupt communication, affecting disaster relief
organizations, command and dispatch, personnel search and rescue, and secondary disaster
prevention processes.
The emergency satellite communication system (International Maritime Satellite) cannot support
real-time communication due to the overload of the rescue units and personnel at the rescue site.
The Beidou satellite system can only provide communication services at this stage. Many rescue
teams do not have rescue emergency communication system support, so the information on the
rescue site cannot be sent to the rescue site headquarters and the rear emergency center in
real-time. The rescue team entered the core area of the quake-hit area and the work process
after entering the rescue team was basically out of communication with the rescue site
headquarters and the rear emergency center.
A common emergency communication system is an emergency communication vehicle, but when
road damage or collapse occurs, its use is limited. In addition, in the past two or three years, with
the breakthrough of key technologies such as brushless DC motors, high-energy lithium polymers,
and multi-rotor coordinated control, micro-small multi-rotor drones have gradually matured.
Therefore, portable communication base stations, that is, air emergency base stations based on
tethered drones, have become an important solution.
General multi-rotor drones can only fly for 30 minutes to one hour. Tethered multi-rotor drones
can achieve continuous uninterrupted flight. At the same time, because the antenna height can

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increase with the drone's flying height, and the coverage angle can be adjusted with the drone's
rotation direction, it can achieve large-area signal coverage more effectively.
In 2009, German researchers initially tested drones that can provide Wi-Fi network signals. U.S.
carriers AT & T (Flying COW), Verizon and Qualcomm have tested drone-based airborne LTE
network base stations, in addition to Japanese telecommunications operator KDDI's drone base
stations and British EE's LIVE.
Recently, the University of North Texas drone base station has also been field-tested. When the
transmission power of the system is increased to 10W, the coverage can be extended to the
entire city of Denton.
Tethered drone emergency communication high-altitude base station has three characteristics:
1. Long battery life: using the optoelectronic composite cable to power the drone and RRU, the
battery life can reach 8 hours, which is 31 times longer than the traditional battery drone base
station.
2. Strong flexibility: The small off-road vehicle is equipped with a drone communication system,
which can quickly reach the scene of communication interruption and meet the protection
needs.
3. Strong scalability: according to different scenarios of emergency communications,
omnidirectional or directional antennas can be flexibly configured, and packetized microwave or
wireless ring network transmission equipment can be selected. Modularization and flight control
are semi-automatic, and short-term training for ordinary people can be employed.
In addition to responding to the needs of emergency communication channels under natural
disasters, tethered drones are also used for surveillance and reconnaissance, such as the U.S.
Aeronautics and Environment Corporation (AeroVironment) drone system Tether Eye, funded by
CTTSO, and Israel for border surveillance HoverLite, a small drone product interviewed by the
press, CyPhy, and the U.S. military have cooperated with the Pocket Flyer for a panoramic camera
pocket ...
Domestic Solution: Huawei + Mobile + Startup
The main development force of domestic tethered drones is currently China Mobile, and related
applications have emerged in floods, typhoons, landslides, earthquakes, and other disasters, and
in border inspections, base security, scenic area monitoring, geological surveys, field operations,
forest fire-prevention, Emergency communications, public security counter-terrorism, traffic
supervision, news interviews, engineering monitoring, environmental monitoring, film and
television shooting, scientific research, national defense, military industry, and other fields have
some prospects.
Behind China Mobile's tethered drones are the shadows of Huawei (providing 4G base stations)
and a startup (Zhuoyi Intelligent Technology Co., Ltd.). This startup, which is cooperating with two
big brothers, has a team from Beihang University, Tsinghua University, Zhejiang University, and
other universities. There are several Beihang professors and associate professors serving as the
company's technical consultants. It is said that it has already invested tens of millions of yuan.
According to reports, with the emergency communication system quickly established by the
high-altitude base station, the drone can continuously provide a stable signal for 8 hours for an
area of 5 square kilometers (the coverage can reach 20 kilometers at an altitude of 800 meters).

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The deployment can be completed within 2 hours (but the base station team arrived at
Jiuzhaigou in the afternoon of the 10th and the site was opened on the morning of the 11th in
the earthquake. There are still many specific problems to be solved in practical applications). The
average download rate is 36.4Mbps and the upload rate is 5.47Mbps, the average voice MOS
value is 3.4, can provide instant communication services to nearly a thousand mobile phone
users at the same time, to ensure the rescue work smoothly.
Nokia F-Cell: Wireless works too
In addition to tethered drones, Nokia Bell Labs also proposed F-Cell, a drone base station with
integrated solar cell modules, to wirelessly implement self-powering, self-configuration, and
automatic connection to the network, and immediately after networking Start transmitting HD
video. Due to its flexibility (wireless), large capacity, low latency, and scalability, F-Cell will
continue to solve the problems faced by operators and enterprises in terms of a small base
station and backhaul wiring, deployment, and cost. Looking forward to more everyday future
WAN (5G, 4G and LTE 4.5) construction.
It is reported that the F-Cell architecture includes a closed-loop 64-antenna massive MIMO
system at the center, which can distribute 8 beams to 8 self-powered (solar-powered) F-Cells. The
architecture supports non-line-of-sight wireless networks in frequency division duplex (FDD) or
time division duplex (TDD) mode, as well as up to eight independent 20MHz channels running in
parallel, enabling 1Gbps system throughput on existing LTE networks rate. In the future, the
architecture will expand to take advantage of higher spectrum bandwidth, new frequency bands,
and larger antenna arrays to achieve system throughput rates of tens of Gbps.
UAV base stations are expected to become a flexible, reliable endurance communication base
station, especially as an emergency solution for typhoons, landslides, earthquake natural
disasters, and extreme conditions. The technology of tethered drone base stations has matured
and has been successful The wireless small base station solution provided by Bell Labs has more
powerful practicability, whether it is to solve the problem that the ground environment is not
suitable for in-vehicle system entry in the emergency solution, or in the future communication
deployment.