Advancement in GNSS technology in India

Sanat K Biswas PhD Assistant Professor Electronics and Communication Engineering Indraprastha Institute of Information Technology, Delhi, India

The emergence of Global Navigation Satellite System (GNSS) has provided a remarkable opportunity to determine and manage position and time information with precision, for various purposes, ranging from day-to-day navigation to tracking military assets. GNSS constellations deployed by various nations serve as essential infrastructures for navigation and timekeeping. The availability of multiple GNSS, for example, Global Positioning System (GPS), Galileo, GLONASS, Beidou has improved the robustness and reliability of the GNSS-based navigation solution. Recently India has deployed a Regional Navigation Satellite System (RNSS) called Navigation using Indian Constellation (NavIC) to enhance the nation’s Position, Navigation and Timing (PNT) capability.

Modern critical infrastructures such as airports, railways, banking and finance, power grid and communication systems are increasingly becoming dependent on the GNSS Position, Navigation and Timing (PNT) services. GNSS is directly benefiting the economy and transforming our daily life. It has also created an accidental system of seemingly unrelated systems which is enormous in scale and extremely complex. Hence focused national-level research on the advancement of GNSS technology, innovative applications as well as vulnerability analysis and mitigation is of vital importance.

National status

As mentioned earlier, the indigenous space-based navigation system NavIC has reached full operational capability. The space segment of NavIC consists of 7 satellites in geosynchronous and geostationary orbits. The coverage area of this system is 1500 km beyond the Indian territory and the estimated horizontal position accuracy is 20m. NavIC satellites transmit signals in L5 and S-band, and provides both Standard Positioning Service (SPS) for civil applications and Restricted Service for defence applications. It should be noted that even before the deployment of NavIC, India contributed towards global navigation services by establishing Satellite Based Augmentation System (SBAS) named GPS Aided GEO Augmented Navigation (GAGAN). GAGAN ensures the integrity of the GPS service as well as increases the navigation accuracy for safety-critical applications, for example, civil aviation in the Indian subcontinent.

While, Indian Space Research Organisation (ISRO) took the daunting task of establishing the space and ground segments of the satellite navigation system, Indian academic research in this area has been restricted to predominantly at the application level. Several research groups are working on positioning performance analysis of multi-GNSS receivers, NTRIP server development and ionospheric studies. Academic research in GNSS from geomatics and space weather perspective is important. However, there is a strong need for diversifying the research scopes within the GNSS domain, to address immediate national requirements.

One such immediate requirement is the development of a low-cost general-purpose NavIC receiver. Although ISRO and the Ministry of Electronics and Information Technology are partnering with commercial manufacturers for the development and deployment of NavIC receivers, the Indian academic research community can also play a major role in this context. One of the major challenges in the user-segment development sub-domain is designing a low-power GPS-NavIC integrated receiver. The flexibility of the academic research environment can be of advantage in developing innovative hardware and software solutions to this problem. Adding further to the details, research in the direction of reducing the acquisition time and computational resources, reducing the Time to First Fix (TTFF) of NavIC receiver is extremely important to enhance the user experience and performance of the receiver. Another direction can be the development of special correlators for acquiring weak NavIC signals.

Having discussed some direct research trends and outlining plausible research directions, it is now important to discuss the vulnerability of GNSS. As previously mentioned, GNSS connects various otherwise independent critical systems and thus also acts as a single point of failure to this system of systems. GNSS signals are extremely weak by design and can be susceptible to intentional or unintentional interference. This may lead to GNSS service disruption and result in catastrophic failure of multiple critical infrastructures at a single instance. A similar threat is imminent to NavIC as well. NavIC S-band signal was designed to avoid unintentional interference. However, it has been recently observed that the WIFI signal may interfere with the S-band signal. Hence it is of paramount importance to peruse active research in the area of GNSS and NavIC interference source detection, localization and mitigation.

Opportunities

GNSS technology has unfolded various research and entrepreneurship opportunities to improve the overall quality of life. With the availability of NavIC, India has become self-reliant on PNT services in the Indian subcontinent. Hence, application of NavIC standard positioning service is expected to be penetrated in a diverse set of existing services. Also, this will facilitate some emerging applications like precision agriculture and reflectometry.

Automated, timely and efficient execution of various farming tasks sit at the core of precision agriculture and these often depend on spatial information where GNSS service plays a key role. On the other hand, there is an opportunity to repurpose the reflected GNSS/RNSS satellite signals to extract information about various important environmental parameters such as soil moisture, wind speed at the ocean surface, water-body area etc. This method has proved to be very cost effective compared to the conventional remote sensing techniques and known as GNSS-Reflectometry (GNSS-R). There is significant untapped potential in exploiting synchronized S-band and L5 band signals transmitted by NavIC to develop new approaches that can improve the resolution and accuracy of the reflectometry-based solution of various environmental parameter estimations. To facilitate strong national research capability in this emerging area, it is necessary to develop reflectometry capable GNSS/RNSS receiver as well.

Challenges

Although the availability of GNSS and NavIC services created an abundance of opportunities, there are many challenges which must be addressed to facilitate impactful and relevant outcomes in the field of GNSS technology. It is well known that the academic research groups working on GNSS technology in India is very sparse and hence it is imperative that more researchers are needed to be attracted in this research field. Establishment of a national GNSS research society can help the cause.

A substantial amount of efficient workforce is also needed for efficient development, nationwide deployment and maintenance of NavIC receivers. Efforts have been put for workforce development through short courses. However, there are very few academic institutes in India which provide full-fledged courses on GNSS technology in undergraduate and masters level. Hence, it is also necessary to offer more rigorous courses on GNSS signal processing, receiver architecture and navigation algorithms.

Another major challenge is there are very few Indian Original Equipment Manufacturers (OEM) who provide GNSS/NavIC receivers, spares and related supports. More OEMs will allow a diverse range of technological solutions as well as expedite the research and development in this field. Government of India is encouraging the process through the “Make in India” and “Digital India” initiatives.

Conclusion

GNSS technology has opened various possibilities of technological advancements and will play a key role in shaping the society of the coming age. The emergence of NavIC has marked India’s self-reliance on PNTservices and is just the beginning of a technological transformation. It is anticipated that in future NavIC will support critical infrastructures such as airports, railroads, power grids and finance sector, will play a major role in the development of next-generation intelligent transport systems and Internet of Things applications. At this crucial juncture, the Indian academic research communities from various disciplines must assume a pivotal role in GNSS technology development, technology transfer and workforce development.