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Direct-to-Satellite Internet of Things
According to IEEE papers , novel demands from earth observation community have emerged due to current climate situation . These needs are mainly oriented on monitoring hydric stress , climate disasters , among others . These applications require satellite systems capable of providing sub-metric spatial resolution observations . A hybrid architecture which combines in-space with in-situ measurements emerges as a potential approach .
In this scenario , ground sensor devices autonomously perform in-situ measurements with different spatial and temporal resolutions different from satellite ones . These devices must manage their constrained resources and transfer the generated data .
The Direct-to-Satellite Internet of Things paradigm proposes the interconnection of Low Earth Orbit satellites with these devices using standardised protocols .
According to Juan A Fraire , National University of Cordoba , Argentina ; Sandra Céspedes , Concordia University Montreal ; Nicola Accettura , Laboratoire d ’ Analyse et d ’ Architecture des Systèmes ; the most challenging IoT scenarios include deployments of low power devices dispersed over wide geographical areas .
GEO , in contrast has the advantage that it provides a much larger cover area , which also means it requires fewer satellites to deliver global coverage . GEO satellites appear stationary when viewed from a fixed point on the ground , and rotate at the same speed and direction of the earth .
Ground antennas can connect to the satellite by pointing at it , without needing to track its position . This helps make using GEO technology relatively inexpensive , while at the same time , these satellites have a much longer lifetime .
The round-trip time for a GEO satellite is approximately 600 – 800 ms , while data moves back and forth to a LEO satellite in the range of 30 – 50 ms . This would make it seem like LEO constellations are better suited to real-time applications .
However , today ’ s LEO satellite IoT networks have a limited number of satellites in orbit . They are unable to provide continuous connectivity to the entire world , but rather provide an intermittent , periodic coverage .
This means that data points can only be taken from IoT devices a few times every 24 hours as the satellites move around Earth . As a result , the latent GEO constellations are often better suited for near realtime applications , rather than LEO constellations .
In such scenarios , satellites will play a key role in bridging the gap towards a pervasive IoT able to easily handle disaster recovery scenarios like earthquakes , tsunamis , and flash floods , where the presence of a resilient backhauling communications infrastructure is crucial .
In these scenarios , Direct-to-Satellite Internet of Things connectivity is preferred as no intermediate ground gateway is required , facilitating and speeding up the deployment of wide coverage IoT infrastructure .
Growth of LEO
The future of non-terrestrial network looks promising , as the technology continues to evolve and improve . New technologies , such as low-power radio and advanced modulation schemes , are being developed to improve the efficiency and reliability of nonterrestrial network connections .
Additionally , companies are working on reducing the costs of launching and maintaining LEO satellites , making it more accessible for businesses of all sizes to use non-terrestrial network for their IoT applications .
Non-terrestrial network connectivity is an increasingly important technology for connecting devices in remote and hard-to-reach areas .
As the technology continues to improve and costs decrease , we can expect to see more and more devices and applications utilising non-terrestrial network connectivity in the future . p
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