How satellite internet could be a game changer in rural connectivity

Three-quarters of rural India does not have access to broadband service as many locations are still without cellular/fibre connectivity. Satellite medium is the only viable option there for providing broadband service.

For the provision of satellite based service, one of the following three earth orbits is used:

1. Geo stationary (Synchronous) Earth Orbit (GEO): This orbit is at an altitude of 36,000 Km from the surface of earth. The satellite placed at GEO revolves around the earth from east to west at the same speed at which earth rotates around itself (in 24 hrs). So tracking the satellite by earth station antenna is easy. These satellites are ideal for broadcast service. Hundreds of GEO satellites are in orbit today launched by different countries (with separation as low as 0.5 degree) delivering services such as weather data dissemination, TV broadcast, voice communication and low speed data communication. Large coverage is one of the advantages of GEO satellites and theoretically three satellites are enough to cover the entire world. The signal using the GEO satellite has a latency of about 240 milliseconds. Round trip delay is about 480 milliseconds and echo suppressors/echo chancellors are required to be used in the speech channel to have comfortable speech conversation. Lifetime of a GEO satellite is 10-15 years. However, its launching cost is high. Because of high latency, capacity limitation and cost, GEO satellite is not suitable for broadband service.

2. Medium Earth Orbit (MEO): A MEO satellite will be at an altitude of 8,000 to 18,000 Km above the surface of earth. Its rotation period is 2 to 8 hrs. 100-150 satellites are required to cover the entire world. Its lifetime is 10-15 years. Its launching cost is moderate. These satellites are used for GPS and other navigation applications. However, the MEO satellite is not suitable for Broadband service.

3. Low Earth Orbit (LEO): A LEO satellite will be at an altitude of less than 2000 Km. Its orbital period is 10 to 40 minutes. Low latency (20 ms), high capacity and low launching cost are its attractive features that make it useful for provision of broadband service. It is also used in health care, education, tourism and disaster management. However, hundreds of satellites are required to cover the world, and its tracking is complex. Another disadvantage is that its lifetime is only 5 years.

LEO based broadband service:

LEO satellite constellations consisting of many satellites are deployed for providing broadband service. For example: Oneweb has 394 satellites in service as of now of a planned total of 648 to be deployed by mid 2022, and SpaceX has deployed nearly 1900 satellites.Typical Broadband download speed that an individual gets in this service is 87 Mbps. Bharati backed OneWeb, Elon Musk backed Star link which is satellite broadband arm of SpaceX, Tata group company Nelco in partnership with Canada's Telesat and Amazon's Kuiper etc., are keen to launch satellite based broadband services in India.

The satellite based broadband system consists of satellite, User Terminals (UT) and earth station gateway.

User Terminals (UT)

For accessing the satellite constellation, an electronically steerable flat panel antenna is fitted to the User terminal. User Terminal is typically of briefcase size. It is plug and play type and can be remotely configured. Right now they are of fixed type (no mobile UT) and the UT is locked to the user's provided address. In two to four years, mobile UTs will be available. Each UT has a GPS. Using a Wi-Fi router multiple users per UT can be supported. A Wi-Fi router converts satellite signals to Wi-Fi allowing smartphones, laptops, tablets to plug on to the internet. By setting the parameters some specific zones can be excluded from the coverage of satellite based broadband service, keeping the security angle in view. In 1998 Iridium launched LEO satellite constellation based phone service. One of the reasons for the failure of Iridium is the large size and weight of the handset (User Terminal).

Satellite earth station gateways

A satellite earth station gateway is a ground station that transmits data to/from the satellite to the local area network. It is a key infrastructure resource for offering phone/ broadband service from satellite. Currently there is one satellite gateway in our country located in ALTTC campus, Ghaziabad to facilitate satellite phone services via Inmarsat satellite. Satellites operating in multiple narrow beams need to set up multiple gateways. LEOs operate through narrow beams with a typical span beam about 250 km. They require ground stations every thousand kilometers. A satellite earth station gateway controls a LEO satellite constellation. Oneweb gateway has a 3.4 m antenna with Ku band uplink and Ka band downlink. As per licence conditions issued by DOT, Earth station gateway should be an Indian entity. These licence conditions mandate a licensee to establish its own gateway for rendering any kind of satellite based communication service.

For framing new licensing rules for setting up of in-country satellite gateways by LEO satellite service providers, TRAI has invited comments from the stakeholders. It has also sought views on ways to assign spectrum for the establishment of such satellite gateways.

Weather satellite spectrum is to be auctioned or to be given on an administrative price?

Ku band (12.5 GHz to 18 GHz) and Ka band (26.5 Ghz to 40 GHz) are used in LEO satellite service. Global satellite service providers and Airtel in their submission to TRAI have opined that that satellite gateway spectrum should be allotted through the administrative route charged at standard pricing in line with the global practices. Reliance Jio informed TRAI that spectrum allocation should be done via auction, mentioning that the auction route would be in line with the Supreme Court judgement in 2012 (that had backed allocation of airwaves via transparent auctions). DoT/TRAI has to take a call on how to allot the spectrum to LEO operators for establishment of satellite gateways.

Way forward

• In remote, hilly and inaccessible areas where broadband service can't be provided through other media, satellite medium is only the option. Since the user terminal of LEO satellite based broadband service is not affordable to common man (the price of a user terminal of Starlink is around Rs 1.58 lakh), support from USO (Universal Service Obligation) fund should be made available.

• Unlike GEO satellite service, in LEO satellite service many satellites are required to be deployed. LEO satellites are to be replaced every five years. With nearly 30,000 satellites and other debris orbiting the planet, countries have to share data to reduce the risk of catastrophic space collisions and controls to prevent collisions should be put in place. Also a mechanism should be there to remove satellite debris from space periodically.

• BSNL should lease satellite bandwidth from one of the LEO satellite operators and provide broadband service in BAHAR (Backward Hilly and Remote) areas (where other medium is not feasible) using its earth station gateway at Ghaziabad.

(The author is a former Advisor, Department of Telecommunications (DoT), Government of India)