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Augmenting GNSS CORS Infrastructure in a scalable manner

Xavier Banqué-Casanovas

GNSS infrastructure is a powerful asset to enable the necessary precise navigation in a myriad of applications that will come along with the automation revolution (autonomous driving, location-based services, robotics, smart agriculture…). However, its deployment, maintenance, and operations are expensive and cumbersome.

GNSS Continuously Operating Reference Stations (CORS) have been traditionally used for accurate navigation that relies on Real-Time Kinematic (RTK) technology and techniques such as Virtual Reference Stations (VRS), targeting applications such as geodesy or surveying.

The arrival of mass-market applications that needs accurate and scalable navigation solutions has changed the rules. Scalability involves not only that the technology can scale to reach hundreds of thousands of users, but affordability so that mass-market applications’ budgets can take on this new navigation technology.

The challenges of the RTK navigation techniques

Principal drawbacks of the RTK technique hindering scalability are: (a) lack of CORS infrastructure to have a full territory coverage, and (b) the ad-hoc nature of the solution when generating on-demand VRSs for each user. UNION project proposes a concept to break these limitations to make accurate navigation accessible for mass-market location applications.

Therefore, the technological challenge addressed by UNION is to give a twist to the classical RTK concept based on using CORS infrastructure to overcome the scalability constraints and make this technology accessible for mass-market applications in need of accurate navigation. UNION’s proposed solution tackles two limitations that hinder classical RTK from being a suitable technology for applications: featuring a wide-area coverage and supporting a massive number of simultaneous users.

UNION project is getting promising results!

Our #location stack can locate a user with less than 0.4 meters of #accuracy 🎯(lane level navigation🛣️) with a Virtual Reference Station located more than 100 km away from the rover 📱🚗#GNSS #Galileo #EUSPA #RTK #PPP pic.twitter.com/xiDuvWT4ZD

— Union project (@GsaUnion) February 18, 2022

Developing a network of Permanent Virtual Reference Stations

Usually, the intelligence of the system in charge of establishing a bidirectional communication session with the users lies in the infrastructure/service. The project proposes turning around the original concept to generate an ad-hoc VRS for each user so that the intelligence swaps to the user segment.

The core proposal is to generate and continuously operate a network of Permanent Virtual Reference Stations (P-VRS) that densifies the current real CORS network. Therefore, a wide-area territory has a GNSS base station coverage with baselines under 20km. The service segment of the UNION technology will be in charge of operating and serving this P-VRS Network, which will be provided via an NTRIP caster that aggregates the P-VRS network and the real CORS network.It will be on the users’ side to connect to this caster and select the closest GNSS reference station(s) (either real or virtual CORS) to get a correction streaming for RTK navigation.

Thanks to this technique, there is no need to generate an ad-hoc VRS for every user. Besides, the GNSS reference station coverage is enough to guarantee a precise navigation corrections service in a wide-area territory. Thus, the UNION solution will be able to scale up to hundreds of thousands of simultaneous users demanding GNSS corrections for accurate navigation, enabling precise location for mass-market applications such as Location-based services or autonomous vehicles.

Figure 1. Proposed network of P-VRS station
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