The Internet of Things (IoT) is a system of interrelated computing devices, mechanical and digital machines, objects, animals or people that are provided with unique identifiers (UIDs) and the ability to transfer data over a network without requiring human-to-human or human-to-computer interaction. The Internet of Things (IoT) is now globally proliferating to intelligently connect devices in order to meet increasing consumer demands as well as improve productivity. There are various smart devices, such as sensors, smartphones, and wearables, which collect necessary data from the devices which are further utilized to enhance customer’s experience. The internet of things technology helps in connecting various smart devices together to ease the operation and sharing of data amongst themselves.
The current IoT leverages existing wired and wireless network infrastructures for communications and control. The dominant communications technologies for IoT have been short-range technologies including Wi-Fi, Bluetooth, and Zigbee. Cellular networks are another emerging connection technology and the number of IoT device connections to cellular networks is predicted to increase from 1.2 billion in 2019 up to 4.7 billion in 2030.
However, as IoT devices continue to proliferate in parallel with higher data rate communications and data services, these existing networks will become increasingly stressed and congested, particularly in remote and underserved regions of the world. For some harsh environments, such as deserts, forests, mountains, and oceans, the terrestrial network cannot be covered entirely. Additionally, in the face of natural disasters, such as floods, earthquakes, tsunamis, etc., the terrestrial network is vulnerable. With its extensive coverage and strong system invulnerability, satellite communication systems can provide access services for IoT terminals in remote areas, realizing the “Internet of Everything” in the real sense of the world.
The long-term success of IoT is tied to its pervasiveness, which is constrained by the limited coverage of terrestrial mobile broadband networks, which for commercial reasons cover areas with relatively high population densities. The true potential of IoT can only be realized when it is augmented with a ubiquitous connectivity platform capable of functioning even in the most remote of locations. It is possible to expand the area of providing IoT services by using the satellite telecommunication systems resource, with specified and widespread application.
With the development of microsatellite technology, the cost of satellite development and deployment has decreased significantly. Low earth orbit (LEO) satellite constellations have begun to provide powerful support for IoT devices. LEO satellites orbit between 400 and 1,000 miles above the earth’s surface. Data that is transmitted in LEO is sent from one satellite to another as the satellites generally move in and out of the range of the earth-bound transmitting stations. LEO is ideal for many communication applications because it takes much less energy to place the satellites into LEO and can use less powerful amplifiers for transmission.
Also, operating at low earth orbits, satellites will also significantly reduce network latencies, while introducing challenging tracking, synchronization and handoff issues. Advances in microwave/mm-wave phased array technology and advanced CMOS over the last several years will also be key enablers. The new networks should not be expected to replace terrestrial networks, but will integrate seamlessly with these networks to provide ubiquitous global connectivity.
The shaping of the future of space will involve new information communication technologies (ICT) involving today’s collection of technologies often termed as the Internet of Things (IoT), with connectivity technologies increasingly being combined with computing and large-scale data processing capabilities powered by Artificial Intelligence (AI) and Machine Learning (ML) technologies. For instance, one of
the key visions of the fifth/sixth generation (5G/6G) mobile networking technologies is to realise a Space, Air, Ground Integrated Network (SAGIN).
Internet of Space Things/CubeSats (IoST).
The nanosatellite era is set to further expand the IoT’s scope. Nanosatellites are loosely defined as any satellite weighing less than 10 kilograms. These satellites become IoT nodes with sensing, computation and communication capability. The devices work in swarms to collect information. Networks of nanosatellites aren’t just about acting as sensors – these devices can also provide global connectivity and transmission, important qualities for IoT-using businesses to have. Therefore researchers are focussing on the development of a novel cyber-physical system spanning ground, air, and space, called the Internet of Space Things/CubeSats (IoST).
IoST expands the functionalities of traditional IoT, by not only providing an always-available satellite backhaul network, but also by contributing real-time satellite-captured information and, more importantly, performing integration of on the ground data and satellite information to enable new applications.
Some of the Use cases for IoST applications are Remote sensing, Monitoring of terrain and assets, Exploration of the deep space, Management of global transportation, Inter-CubeSat or ground-station data transmission and Disrupted or underserved areas have limited Internet access.
Leading companies around the globe have started seriously considering the concept of the Internet of Space (IoS). Both NASA and ESA have prepared plans to deploy satellite networks around Earth, spanning Mars and the Sun. The networks consist of microwave antenna arrays with miniaturized satellites and lasers pointing through free space. In the coming years, these technologies will provide the communication networks needed for connected robots and landers that will explore and possibly mine lunar and Martian surfaces.
The space-based network leverages software-defined networking (SDN) and network function virtualization (NFV) to control and manage a system of miniaturized satellites (CubeSats) and ground-based sensing devices. Deployed in the exosphere, an ad hoc network of CubeSats plays a central role in the system, serving not only as the network infrastructure but also as passive and active sensors. Nanosatellite development based on CubeSat standards guarantees ongoing and relatively inexpensive access to space, as well as a wide range of launch and space rocket options.
NASA has selected two photonics-based proposals to develop new technologies for small satellite applications, ultimately intended to improve science observations in deep space and to help the agency develop better models for predicting “space weather”. Funded under NASA’s Heliophysics Solar Terrestrial Probes program, which is managed by the Goddard Space Flight Center, the two technologies involved are optical communications for CubeSats, and a giant solar sail for propulsion.
The first of the projects is actually looking to develop two different technologies: one of those is an optical communications link for small satellites and CubeSats that is less complex than current systems. Switching from RF to optical links in space offers the potential for a hundred-fold increase in deep-space data rates, while also reducing the burden on NASA’s existing Deep Space Network. “Such technology could help support future small satellite constellations that require high data rate communications systems,” stated the agency, which has appointed Antti Pulkkinen at Goddard as principal investigator.
Enabling technologies for Internet of Space Things/CubeSats (IoST).
Experts believe that IoT will be enabled when these satellites can communicate with each other wirelessly. This would allow future satellites to communicate with each other in a mesh network as well as reduce the weight and increase the payload capacity of traditional satellites. Technology already exists to provide internet access using satellites in geosynchronous orbit, but satellites in LEO offer more advantages as they are less expensive as well as enable lower latency.
Enabling keys to the new wave of companies are open standards and smaller hardware. CubeSat technology to drive down the price of IoT monitoring, with some promising to push pricing down to as little as a few dollars per month per device. CubeSat standardisation opens up the possibility of using commercial electronic parts and the choice of numerous technology suppliers, thereby considerably cutting the costs of CubeSat engineering and development projects in comparison with other types of satellites.
CubeSat standards enable startups to quickly build and test satellites the size of a shoebox or smaller. With smaller size comes lower drastically lower launch costs. A typical 3U (30 cm x 10 cm x 10 cm) CubeSat designed to relay data can be built and put into orbit for $1 million or less. A pair of satellites in the proper orbits can provide global coverage with a 12 hour or less service interval to pickup data from a remote location.
The space-based Internet-of-Space network will represent the support framework for IoT with advances in millimeter-wave phased array technology and 5G system developments. Chip-scale phased array system-on-a-chips, which are applicable to low-cost silicon technologies with an adequate and equivalent isotropically radiated power, would enable links with transiting LEO satellites and act as technology enablers.
In Massive IoT applications terminals are deployed in large quantities and thus are under cost and resource constraints. Such constraints include size of the terminal, bill of materials, energy budget for battery-powered devices, permitted transmit power and antenna performance. Typically the amount of data transmitted by each terminal is small and transmissions occur infrequently. Thus, even if the spectral efficiency of the satellite link may be low, each terminal only consumes a small fraction of the available satellite bandwidth.
Their system is designed for flexibility with multi-band connectivity to enable a wide range of geostationary and near-geostationary endpoints, including terrestrial, below ground, and underwater locations. Security is built into the IoST architecture through the use of different security profiles and delievered as-a-service to protect the availablity, integrity, and privacy of all connected resources and information.
For most antennas, the beam width is indirectly proportional to the size of the antenna, i.e. a small footprint antenna has limited gain and directivity, thus produces a wide beam. This results in unwanted emissions toward adjacent satellites in the GEO arc and other LEO or HEO satellites or terrestrial receivers. Therefore, to mitigate such harmful interference into other systems, direct-to-satellite IoT terminals need to comply with defined power spectral density (PSD) masks. Depending on beam width and pointing accuracy, such PSD masks significantly limit the permitted transmit power, link efficiency, system capacity and the number of IoT terminals in the network.
Technologies that address the efficient use of spectrum and maximizing system capacity in such PSD-limited scenarios are required considering terminal and antenna type and pointing accuracy. Furthermore, a waveform implementing such concepts has been developed and is available in simulation.
First plant-powered IoT sensor sends signal to space
The first-ever plant-powered sensor has successfully transmitted to a satellite in space. The pilot service, using plants as the energy source, has been developed by Plant-e and Lacuna Space. Combining the innovative energy harvesting technology developed by Plant-e with the extremely power efficient devices from Lacuna Space, these devices are completely self-sustainable and operate independent from sunlight, day and night.
The Internet of Things (IoT) prototype device, developed by the two companies, uses the electricity generated by living plants to transmit LoRa messages about air humidity, soil moisture, temperature, cell voltage and electrode potential straight to Lacuna’s satellite. Future applications can be found in critical data gathering from agricultural land, rice fields or other aquatic environments without the need for any external energy sources. The pilot service is supported by the ARTES programme from the European Space Agency (ESA).
Plant-e, a start-up from Wageningen, the Netherlands, has developed a technology to harvest electrical energy from living plants and bacteria to generate carbon-negative electricity. The output generates enough energy to power LEDs and sensors in small-scale products
Lacuna, based in the UK and the Netherlands, is launching a Low Earth Orbit (LEO) satellite system that will provide a global Internet-of-Things service. The service allows collecting data from sensors even in remote areas with little or no connectivity. At the moment Lacuna Space is offering a pilot service with one satellite in orbit, and three more satellites are awaiting launch during the next few months.
“At ESA we are very enthusiastic about this demonstration that combines biotechnology and space technology,” said Frank Zeppenfeldt who works on future satellite communication systems in ESA. “A number of new opportunities for satellite-based Internet-of-Things will be enabled by this.”
High-throughput satellite (HTS) applications require the use of high gain antennas, perfectly pointed toward the satellite of interest. Active antenna tracking and beam repointing is compulsory whenever the ground terminal or the satellite moves, e.g. for terminals used in LEO or HEO constellations or for mobile terminals used on GEO satellites. Active beam pointing capabilities are also highly advantageous to simplify installation of fixed terminals operating on GEO networks.
Size and complexity constraints prohibit the use of mechanically steerable reflectors or electrically steerable phased arrays for »Massive IoT« applications. On the other hand, throughput requirements for IoT are low compared to HTS use cases, allowing compromises on antenna gain and directivity. This favors the use of multibeam antennas that provide adequate gain and beam steering capabilities while keeping antenna size, number of radiating elements and complexity of the excitation network low.
NASA demonstrates inter-CubeSat laser comms
NASA has announced that two of its CubeSats have been teamed up in an impromptu optical communications pointing experiment. In a video on the NASA website the laser beam can be seen as a brief flash of light close to the center of the focal plane, to the left of Earth’s horizon.
The light is transmitted from the laser communications system onboard one of two Optical Communications and Sensor Demonstration (OCSD) spacecraft. The laser flash was recorded by a short-wavelength infrared camera, one of three cameras comprising the CubeSat Multispectral Observation System (CUMULOS) payload, onboard the Integrated Solar Array and Reflectarray Antenna (ISARA) spacecraft. At the time of the demonstration, the OCSD and ISARA spacecraft were both 450 km (280 miles) above Earth and about 2400 km (1500 miles) apart.
The optical communications beam was deliberately aimed at and swept across the ISARA camera. This demonstration shows that an optical crosslink between two CubeSats is feasible with proper pointing and alignment of the emitting and receiving spacecraft.NASA comments that, “Optimizing this capability could enable constellations of small satellites to transfer high volume data between one another in low-Earth orbit or even in orbit around the Moon.”
Characteristics built into the design and operation of small spacecraft enable impromptu experiments such as this optical crosslink test. Their flexibility and responsiveness provide mission operators the ability to take advantage of opportunities to perform additional maneuvers and procedures not previously envisioned for a particular mission. Originally designed to be Earth facing, both the ISARA camera and OCSD laser were tipped onto their sides to point at one another to accomplish this additional crosslink achievement, an operation much more difficult for larger spacecraft.
Other features visible in the NASA-JPL gathered images include a star (R Doradus, which is one of the brightest infrared stars in the sky) that can be seen moving diagonally down toward the right side of the frame as the satellites orbit Earth, and Earth’s horizon as it meets space. Other subtle stationary points of white are “hot pixels” or digital noise from the camera.
Laser-pointer to help ‘CubeSats’ transmit data to Earth
A new type of laser-pointing platform, developed at MIT, Cambridge, Ma, US, may help launch miniature satellites into the high-rate data game. CubeSats have become game-changers in satellite technology, as they can be sent up in flocks to cheaply monitor large swaths of the Earth’s surface. But as increasingly capable miniaturized instruments enable CubeSats to take highly detailed images, the tiny spacecraft struggle to efficiently transmit large amounts of data down to Earth, due to power and size constraints.
The novel laser-pointing platform, which is described SPIE journal Optical Engineering, enables CubeSats to downlink data using fewer onboard resources at significantly higher rates than is currently possible. Its developers say that, rather than sending down only a few images each time a CubeSat passes over a ground station, the satellites should in future be able to downlink thousands of high-resolution images with each flyby. “To obtain valuable insights from Earth observations, hyperspectral images, which take images at many wavelengths and create terabytes of data, and which are really hard for CubeSats to get down, can be used,” commented Kerri Cahoy, associate professor of aeronautics and astronautics at MIT.
“But with a high-rate lasercom system you’d be able to send these detailed images down quickly. And I think this capability will make the whole CubeSat approach, using a lot of satellites in orbit so you can get global and real-time coverage, more of a reality.” Cahoy, who is the Rockwell International Career Development Associate Professor at MIT, is a co-author on the paper, along with graduate student Ondrej Cierny, who is the lead author.
Cahoy and her team looked to develop a precise laser-pointing system that would minimize the amount of energy and time required for a downlink, and enable the use of lower-power, narrower lasers yet still achieve higher data transmission rates. The team developed a laser-pointing platform, slightly larger than a Rubik’s Cube that incorporates a small, off-the-shelf, steerable MEMS mirror. The mirror, which is smaller than a single key on a computer keyboard, faces a small laser and is angled so that the laser can bounce off the mirror, into space, and down toward a ground receiver. Cierny also developed a calibration technique that determines by how much a laser is misaligned from its ground station target, and automatically corrects the mirror’s angle to precisely point the laser at its receiver.
The technique incorporates an additional laser wavelength, into the optical system. So instead of just the data beam going through, a second calibration beam of a different wavelength is sent through with it. Both beams bounce off the mirror, and the calibration beam passes through a “dichroic beam splitter,” a type of optical element that diverts a specific wavelength of light — in this case, the additional wavelength — away from the main beam.
Cahoy says that this achievement result means the technique can be easily tweaked so that it can precisely align even narrower laser beams than originally planned, which can in turn enable CubeSats to transmit large volumes of data, such as images and videos of vegetation, wildfires, ocean phytoplankton, and atmospheric gases, at high data rates.
Hybrid terrestrial-satellite systems
Hybrid terrestrial-satellite systems require both in-depth understanding of terrestrial IoT and satellite communication. While it may appear attractive to use the same technology and waveforms for terrestrial and satellite communication, competing requirements and technical constraints – low power and low cost terrestrial communication in unlicensed bands below 1 GHz vs. PSD constraint and highly regulated satellite communication at frequencies above 10 GHz – favor a hybrid solution, optimized for terrestrial and satellite.
DVB-S2X for Critical IoT applications
Critical IoT applications and aggregation nodes in hybrid terrestrial-satellite systems demand for dependable, low latency and high-throughput connections. These requirements are similar to those for high-throughput satellite (HTS) broadband, but with the additional challenges of using smaller antennas or operating in a LEO or HEO satellite infrastructure. Therefore, additional aspects like low signal-to-noise (SNR) link budgets and time variant channels (variable frequency shifts and path delays) have to be considered when selecting and tailoring the communication standard.
For professional equipment and broadband applications, DVB-S2X is the latest in the DVB-S series of satellite communication standards. For IoT applications, DVB-S2X provides unique advantages by supporting very low signal-to-noise ratio (VL-SNR) operation down to -10 dB and a low-overhead super-frame structure. Especially the DVB-S2X super-frame format 4 provides a flexible extension with VL-SNR payload header (PLH) tracking. This allows robust synchronization and signal decoding under variable channel conditions.