Satellite and remote connectivity means connecting people and machines in places that no mobile tower or fibre cable reaches. Think of four places: a ship in the middle of the ocean, an aircraft 11 km up, an army patrol in hills that block every signal, and an electricity meter in a basement. Three different technologies reach them: satellites, mesh radios and cellular modules.
These are not three steps of one system. Each is a separate business. Satellites reach ships, aircraft and, more recently, ordinary phones. Mesh radios link a group of people who are far from any tower. Cellular modules put machines, such as meters, on the ordinary mobile network.
Satellites fly at two very different heights, explained in LEO and GEO satellites. A geostationary (GEO) satellite sits about 36,000 km up and stays fixed over one spot, so a few of them cover most of the planet. But each signal takes about a quarter of a second to go up and come down. Low Earth orbit (LEO) satellites fly much lower, many at 500 to 600 km. Their signal is quick, but each one moves fast across the sky, so hundreds or thousands are needed. Speed and delay are explained in bandwidth and latency.
Imagine a cyclone that hits the Odisha coast at night. Mobile towers along the coast lose power.
At sea, a cargo ship keeps its internet through a maritime satellite internet service, and receives the latest storm track. In the morning, a relief team flies in from Delhi. On the plane, the team leader reads the overnight reports over in-flight Wi-Fi.
Above the coast, Earth observation satellites photograph the flooded villages. Their images reach the ground sooner through laser satellite communication and a satellite data relay network. The relay network passes data between satellites until one of them is over a ground station.
In a village with no working tower, a family's phone sends a short SOS message straight to a satellite. This is direct-to-device satellite service. It works only on phones and mobile plans that support it, and in India it is not yet widely available.
On the water, the rescue boats carry mesh radios. Each radio passes messages on for the others, so the group forms its own mesh network with no tower. Days later, power returns. Each smart meter reports that its home has power again, through its cellular IoT module.
India opened its space sector to private companies around 2020. So many Indian start-ups now build parts of these systems, from laser terminals to relay satellites.