High-Altitude Platform Station (HAPS)

A High-Altitude Platform Station (HAPS) is a sort of telecommunications structure which has been coordinated to be in the stratosphere at the height of about 20 km (12.4 miles) above the planet’s surface. These platforms are used to supply telecommunication and other services in a broad coverage and are considered as a link between SAT systems and ground networks. HAPS are in many cases not seen as a solution for providing access to remote or rural areas. The range of a single HAPS may vary from 25 to 200 km depending on the design of the platform and type of technologies used. Most HAPS are solar operated to ensure longevity of the mission although some may depend on battery energy among others. HAPS can mimic pseudo-satellites, and can offer useful services, such as broadband internet, 5G, IoT connectivity or another type of data link.

There are two main versions of HAPS: Such as lighter than air (approved for use as balloons or airships) and heavier than air (admitted for aeroplanes). Both types have many general technical similarities; the differences are because the construction features are different.

Like any Aircraft or satellite All HAPS are sophisticated systems which come with their unique development issues regarding ; or weight and power and energy supply. Measures have been put in place to underscore this assertion of the fact that HAPS are doable given the impressive advancement that has been realised in the emergence and disruption technologies.

HAPS are important because they close the gap between satellites and aircrafts. Another of the benefits that which that such a technology holds is that such a technology is able to hover for extended periods of time. HAPS can also come back to land to fix some problems, as well as modification of onboard equipment and then fly again.

Fixed-Wing UAVs

The HAPS used fixed-wing UAVs that aerodynamically have long and slender wings to suit the thin stratosphere environment. Each wing has solar cells, which provide power during the day, and high power density batteries for use at night. Constructed with lightweight yet strong composite materials such as carbon fiber these UAVS are exceedingly resilient to high altitudes and other unfavourable conditions, can stay aloft for weeks or even months. Hazards are auto-steered by autopilot and AI systems to keep stability and course while responding to changes from the environment. Located closer to the surface than Satellites it has added advantage of Low latency and hence can be used to deliver Broadband & 5G connectivity to unserved or undeserved areas.

Airships and Balloons

HAPS I- airships and balloons used in the system are huge; helium filled platforms that fly or hover in stratosphere for communication and data collection equipment. They provide high payload accommodation; hence suitable for accommodating more massive communication systems. Commonly solar operated these structures are made of light materials which are immune to UV light at high altitude. If designed with a frame of an airship, the craft can be controlled by electric motors, usually balloons are moving along the programmed route as there are very accurate GPS used for positioning. Their immobility afford them the capacity to avail long term or broad coverage communications, surveillance or monitoring of an environment.

Hybrid platforms

The design of Hybrid HAPS platforms includes factors of both fixed-wing UAVs and airships that have the most significant endurance and payload capability but less manoeuvrability. These platforms are optimally powered by solar power, backed up with batteries or other forms of energy. Compared to the conventional airships, hybrids are more mobile, they can shift location or stay anchored due to their electric propulsion that can maneuver the stratospheric movement of the structures. Their design conventionally employs lightweight structures for long service, and are more stable than the UAVs on their own; thus have a wide ranging uses including service deliveries of broadband connections right through to environmental surveillance of large areas specifically regions which are hard to reach.

The Beginnings of HAPS Development

Stratospheric flights can be traced back to the 1930s, with the first attempt by Swiss scientist Auguste Piccard who flew a balloon with a pressurized gondola to the stratosphere. Technological developments of the fifties and sixties in the form of jet engines incorporated the Canberra, U-2, and SR-71 aeroplanes as well as rocket motors in experimental planes such as X-1 and X-15 intended for high flight in the Stratosphere.

The specific development of High-Altitude Platforms HAPs began much later in 1969 with High Platform II project an unmanned solar power air ship built by Raven Company with assistance from the US navy. This 25-meter, 62 kg airship, equipped with a 300 Watt electric propulsion system, was first airship to make a power stratosphere flight in 1970 flying upto an altitude of about 21000 meters. Even though it only had a one-hour flight time the plane proved that solar energy can be effectively utilised in high altitude flights.

Because of military application, during the seventies and eighties, some other projects such as the Powered Balloon (POBAL), supported by the US DoD and High Altitude Superpressure Powered Airship (HASPA) were developed. But these early attempts met with problems and were not carried on; it is to this day a rare achievement which requires a reliable and controlled aircraft to accomplish at a time when appreciable altitude showed a tendency to be unstable and highly unpredictable, these early experiences failed to be continued.

High Platform II Airship, 1970, Raven

Partnerships

• Airbus has teamed up with Salam to improve HAPS services in Saudi Arabia employing Airbus’ Zephyr. The partnership plans to establish private networks, IoT services, and response to emergency solutions, all connected through 5G technology and with high-res imaging from the stratosphere. This program contributes to achieving the goals of Saudi Arabia Vision 2030 through enhancing the connection as well as digital solutions.

• Mitratel has partnered with AALTO HAPS with a view of deploying the Zephyr solar-powered HAPS for Indonesia. Using this partnership, Mitratel is well positioned to draw on its network consisting of over 38,000 towers and fiber optic network to solve some of the connectivity obstacles especially in the 3T areas namely, and disadvantaged areas in Indonesia. The main goals of the Zephyr platform are to achieve terminal 5G communication and to improve EO capabilities.
• UAVOS and Bayanat, a subsidiary of the Abu Dhabi-based G42, said they would work together on next-generation high-altitude platform stations. These common efforts are expected to enable various missions in connectivity, earth observation, weather, security, and disaster response. This entails using UAVOS ’ApusDuo aircraft; improving high-altitude operations; and guaranteeing telecommunications networks from the stratosphere, beneficial during catastrophes.

• NTT DOCOMO, JSJT Partner Sky Perfect JSAT, NICT, and Panasonic successfully conducted a test of the non-terrestrial 38GHz band for HAPS. The trial was a replica of future 5G services from the stratosphere. Cessna aircraft was employed at 4km height to perform aerial backhaul test to ground station as a world first for 5G backhaul of HAPS.

Source: group.ntt

• In the HiQ project, the major innovation is the utilization of High-Altitude Platforms (HAPS) for Quantum Key Distribution (QKD) to develop secure communication/networking studies. Unlike satellites, the HAPS provide better regional coverage with increased efficiency since they hover at 17-22 km above the ground. This project is a follow-up to the CV-QKD feasibility study and includes demonstration of the technology in cooperation with UK industry partners with the goal of creating a stratospheric quantum-secured network.

Key Patents in High-Altitude Platform Systems

SoftBank Corp – Service Link Antenna Configuration and Beamforming Control in HAPS

One of the major difficulties in using HAPS for communication with ground terminals is achieving and maintaining fixed position and attitude of HAPS in relation to the ground due to influene of wind and pressure at high altitude. These variations can change the dimensions of the area served by this service, or the cell footprint, which may lead to changes in the handoffs between cells, increases in the number and intensity of controlling signals, and interruption of communications where devices remain in an attempt to connect.

The solution is provided by the patent to control valuable properties of a compound and energy level shifts as well as promotion and safety of the compound and other materials. This patent (US11177874B2) offers a novel beamforming scheme that contributes to the stabilization of the coverage of communications. By employing a number of antennas positioned around the HAPS and applying rtSA to adjust the phases and amplitudes of the signals transmitted to the target area, the cell area is ‘locked’ to the ground, regardless of the current state of the HAPS. This results in consistent coverage, low hand over and high reliability of communication making it fit for complex three-dimensional networks in demanding scenarios.

Nokia Technologies Oy – Group Timing Adjustment for Uplink Transmission in HAPS

In the non-terrestrial networks using satellites or High Altitude Platform Stations (HAPS), there are large distances between user equipment (UE) and the network, resulting in large delay in signals. This gives challenges such as a timing problem in communication since 5G normal systems cannot accommodate the large delay in propagation of the signals which is common in NTNs. If the delay of signal varies across wide coverage area, much of communication interference and inefficient data transfer occurs. The patent (US11469815B2) provides details of a method of making further refinements to timing for overcoming the delay problems of NTNs. The coverage area is then divided into smaller groups which can be managed easily and the timing offsets are allocated according to the position of the groups. These group specific adjustment are employed by user devices to time their uplink transmission to the HAPS accurately. This enables facilitation of coherent communication in a bid to reduce, combine as well as enhance the overall flow of a terrestrial network in non-terrestrial networking interfaces

OQ Technology SARL – Efficient Power Management and Synchronization for Non-Terrestrial Networks Using Airborne or Spaceborne Base Stations

Reliable cellular coverage in such areas is a challenging task on the part of the service providers and also expensive as the creation of a conventional cell tower is not always possible. IoT sensors for instance are low power devices and do not always be online hence do not always have constant power supply. Present telecommunication technologies are built for ground immobile structures at high power and fail to adapt to airborne or spaceborn mobile facilities such as drones or satellites. This means there can be spotty contact and the battery is drained, and in general the signals are awful if any at all in zones that lack the standard accommodations we find in modern civilization.

This patent (EP3944518A1) proposes a more intelligent approach of how devices can handle power and connection through the reception of flight path information from the moving base stations. Equipment can anticipate the time when satellite or airborne station will come to operational range and switch on to transmitter or receiver to put or receive information correspondingly. This strategy is selective in that inactive devices are place into a sleep mode where they cannot transmit and thereby preserve battery power. The system also takes into consideration signal delay and signal shift due to the movement of the station so as to ensure that the connection remains a good one. This solution targets IoT devices that in most cases are low on power hence helps them stay connected for longer periods without having to consume lots of energy.

Huawei Technologies Co Ltd – Interference Coordination in High Altitude Platform Stations (HAPS) for Improved Communication

Interference with other ground base stations or other HAPS may be caused when High Altitude Platform Stations (HAPS) are established to offer network coverage from the stratosphere. Beforehand, traditional interference coordination techniques applicable on ground-based networks fail to handle this issue because HAPS occupy more extensive regions and experience flight path variability. This results in interference or clashing of signals, loss of quality in the transmitted signals and unoptimized use of the available spectrum. An appropriate solution provided by the Patent (EP3557780B1) is Interference management between HAPS and ground base stations is the core idea that the patent introduces. That is based on sharing of accurate flight information between the HAPS and ground stations to be able to forecast when and where an interference may arise. The HAPS computes an “interference window” and then provides this information to the ground base station which has been interfered. For these periods when there exist indications of interference the ground station can either change the frequency it is using or switch off some of the carriers it is employing. Such a communication strategy serves as a preventive measure to minimize handover interruption and thus increase the network reliability.

Conclusion

HAPS provide a relatively young and innovative category of technology that combines elements of satellite and terrestrial solutions. HAPS is advanced through multifaceted innovations that aim to tackle central issues in the telecoms and connectivity domain, including signal dependability, power control, interference coordination and communication latency in non- terrestrial based networks.

In fact, the most fitting testimony is the cases of various patents right from leading companies that work on HAPS issues, from stable coverage and efficient power control to interference issues. These technological improvements are allowing HAPS to offer ubiquitous and dependable access to communication services, where connectivity is either scarce or difficult to attain, and also to participate in a vast range of applications, including safety-related services, IoT, environment monitoring, and secure connectivity.

Thus, the future of HAPS is promising, as new developments in this field are made along with more collaborations are seen to be made. As these platforms become better and more optimized, it can be expected that these will have an important factor in the global communications topology that can be used to interconnect the world where no suitable conventional technology is available.