Anirban Ghosh | Associate Professor, Department of Electronics and Communication Engineering, SRM University – AP
The radio wave moves at the speed of light; however, a video chat using a traditional satellite system will make you feel like you are chatting with someone across the chasm. The cause is geometry. The old-school broadband satellites are positioned around 36,000 km from Earth, near the equator, so a round trip would amount to more than 144,000 km and would add 0.5 seconds of delay before the internet could respond.
The novel concept of the current satellite broadband system starts with the basic principle: bring satellites closer. Operators no longer use several huge satellites but operate thousands or hundreds of small satellites placed in the Low Earth orbit around 500 – 1200 km from Earth. Delay is reduced to tens of milliseconds, comparable to the performance of fibre and mobile connections. All other aspects of the system follow from this decision.
The price of being close
A low satellite races across the sky in a few minutes, so no single satellite can serve you for long. The solution is a constellation, a large network in which one satellite is always rising as another sets. Your connection is handed over seamlessly, much like a phone moving between towers. The difference is that here the towers move and you stand still.
Three innovations make this practical. The first is the flat, electronically steered antenna, a phased array with no moving parts that points its beam by adjusting the timing of thousands of tiny elements. It is what made user terminals small and affordable. The second is inter-satellite laser links, which let data hop across space and come down far from where it went up, reducing the need for ground stations. The third is cheaper, mass-produced satellites and reusable rockets, which make launching thousands of them economically thinkable.
Not a tower in the sky
It is tempting to call this “mobile internet from space”, but the two are built differently. A mobile network needs towers every few kilometres, each tied to fibre. That economics works wonderfully in cities and poorly in forests, mountains and islands. A satellite’s cost does not grow with distance from the nearest road. The trade-off is capacity, since each beam is shared among everyone beneath it. Satellites are poor at crowds and brilliant at emptiness.
Why India should care
India’s 5G rollout has been remarkable, with coverage reported in nearly every district. But a district is not a village, and a village is not a hilltop. Think of the Himalayan valleys, the North-East, the Sundarbans, the Andaman and Lakshadweep islands, and fishing boats beyond the coast. Think also of the day after a cyclone, when towers fall and power lines lie broken. A rooftop terminal with a battery can bring a community back online. For a remote school wanting digital classes or a primary health centre wanting a telemedicine link, the sky may be the only road that exists.
Rival or partner to 5G and 6G?
Partner. International standards bodies already treat satellites as part of the cellular family under the name non-terrestrial networks. The 6G vision goes further: a single “network of networks” in which your phone does not care whether its signal came from a tower or from space. Direct-to-phone satellite services, already appearing in some countries, hint at that future. In such a world, towers will carry the crowds, fibre will carry the bulk, and satellites will carry the rest, the last mile that was never worth building.
The careful path
Several providers are already authorized in India, yet commercial services must wait for security clearance and allocation of frequencies. From the perspective of an engineer, such an approach seems quite reasonable. A satellite communications system is vital critical infrastructure. This network transmits the country’s data and requires both the ground stations and a portion of the limited radio frequency range that all other systems use. And this takes time, which could be used to work out prices, data management, and emergency service issues.
What will decide success?
Affordability. Mobile internet in India is among the cheapest in the world, which means the satellite internet solution cannot compete on price. It has to compete with reach. The cost of the terminal and subscription has to be affordable for the people who would use it the most. That also presents an opportunity to develop local capability. ISRO and the thriving space startups can make their own antennas, ground stations, and ultimately, a low-orbit satellite constellation to make the set-ups affordable.
The takeaway
Who launches first will make headlines, but the deeper story is that connectivity is shifting from a map of towers to a blanket over the whole sky. India’s challenge is to weave satellites, 5G and soon 6G into one fabric, so that a fisherman in the Bay of Bengal and a student in Bengaluru are equally online. The best network is the one nobody notices.
