The "Beyond 5G" network is part of the next-generation information and telecommunication infrastructure. The communication area for this network is being considered for expansion. This will be achieved by using both terrestrial and non-terrestrial telecommunication network systems (NTN: Non-Terrestrial Network). Inter-satellite optical communication in Low Earth orbit (LEO) systems are attracting attention. Network construction with these LEO satellites are a key technology for this next generation.

It will not only complement areas where terrestrial communication infrastructure is not yet in place. But also provide a more robust communications network over a wider area. Leading to a safer and more secure society. For Example, spaces where communication services have not been adequately provided in the past. Such as mountain tops, ships/airplanes, remote areas without electricity. Or when terrestrial communication infrastructure is temporarily unavailable such as in the event of a natural disaster.

Research, development, and servicing of LEO satellite constellations for the Beyond 5G era have progressed rapidly in recent years. There is a growing demand for improved radio equipment for onboard satellites. Radios that can communicate at high speeds and withstand the harsh environment of space. However, most of the current optical/wireless communication systems with these abilities are designed for ton-class satellites. Many of them are high power inputs and have high power consumption. These systems are difficult to mount on 100-kg class satellites. Which are a powerful tool for building inexpensive constellations.

Axelspace has been conducting the NICT-funded research project "Research and Development of Radio-Optical Hybrid Communication Technology for B5G Next Generation Microsatellite Constellations". This R and D project aims to construct a satellite constellation network of radio-optical hybrid communication using 100kg-class microsatellites. With the goal that they can communicate with Gbps-class satellites and the ground. Radio-optical hybrid communication requires precise satellite attitude control to establish optical communication links.

Optical communication is generally faster than radio communication. Yet, it has the disadvantage of being completely disabled in clouds. For that reason, we aim to construct a hybrid radio-optical communication system. This system will use the Ka-band and is expected to be faster than radio communication.

In contrast, the hybrid radio-optical communication system has a new difficult conflicting challenge. The system must not interfere with the precise attitude control while proving the high speed comparable to optical only.

The key technology to solve this has been researching collaboratively with Tokyo Tech. We have been jointly developing Ka-band phased-array radios and broadband Ka-band communicators together.

In space there is a high level of radiation and the environment is harsh. Electronic components are subject to degradation due to this radiation. The amount of radiation received differs between the inside and outside of a satellite. Electronic components placed on the outside tend to deteriorate more than those placed on the inside. Thus, normally electronic components are placeds on the inside of a satellite.

Often, they are also protected by shield to reduce radiation. But this isn't always the case. After a satellite is launched into space measuring radiation exposure is possible. But accurately getting the current degree and location of degradation is difficult. The amount of degradation of electronic components calculated from the track life must be considered at the design stage. The system must be designed so that it does not lose functionality even under conditions of maximum degradation.

Many phased array radios for terrestrial applications have recently begun service. Such as the millimeter wave band 5G communications. These phased array radios integrated the antenna and phased array IC on the same substrate to reduce size, weight, and cost. These Antenna and ICs can't be mounted separately. When mounted on a satellite, they are inevitably placed outside the satellite.

This means that the phased array IC is exposed to space and placed in a very harsh radiation environment. Therefore, the challenge is to overcome the aging degradation of phased array ICs due to radiation. There is a need to develop a phased array radio system that is robust against the radiation environment.

The newly developed phased array IC from this research incorporates a radiation sensor. This sensor measures the amount of radiation degradation in the IC. The amount of radiation degradation at any location on the array can be detected using this IC. The radio equipment can then be reconfigured. And by adjusting the parameters we can compensate for the degradation of radio performance. Consequently, avoiding the degradation of the overall phased array radio performance. And thus, a radio communication system that is more resistant to radiation has been developed.

We will continue our collaborative research with Tokyo Tech. Development of phased array radios for transmission is also in progress. Using and taking advantage of the results of our research to so far. Within a few years, we plan to launch a small demonstration satellite. It will be equipped with the radiation tolerant and power-saving Ka-band communication subsystem.

This Ka-band communication subsystem integrates both receiving and transmitting phased-array radio system. This system is the results of this collaborative research. The broadband Ka-band transmitter/receiver system is under development at Axelspace. We will build a highly functional next-generation satellite and satellite constellation utilizing this new radiation-resistant phased-array radio technology. And in doing so we will create a future in which space is more accessible and usable for everyone.

Related Links
Axelspace Corporation
Space Technology News - Applications and Research