The Hybrid Overlay Positioning with 5G and GNSS (HOP-5G) project targets the demonstration of a 5G local overlay testbed for enhanced user positioning, in combination with GNSS and sensor technologies. Within this project, the HOP-5G consortium focuses on the exploitation of 5G innovative positioning enablers and their hybridisation with GNSS and sensors. This is based on the dedicated deployment of 5G base stations (BSs) fixed on ground and BSs boarded in Unmanned Aerial Vehicles (UAVs), leading to the so-called 5G local overlay network. As a result, this activity develops a first of-a-kind testbed able to demonstrate proof-of-concepts use cases of hybrid 5G and GNSS positioning.
GNSS has become the corner stone of worldwide positioning applications, and in particular for those requiring high-accuracy. The outstanding performances in open sky and very competitive performances in degraded environments of GNSS are widely acknowledged, but also the need to complement GNSS by other technologies to address specific needs in challenging environments. In this context, 5G appears to be among the most suitable candidates to complement the GNSS; IMU technology-mix currently representing the state-of-the-art for robust and high-accuracy applications. 5G technologies could provide high performance TDoA measurements under specific assumptions, which include very good synchronisation among nodes (e.g. 5G nodes disciplined to GNSS), and Line-of-Sight conditions between the node and the user equipment (UE). The latter assumptions may be considered reasonable within dense, local positioning infrastructures, also known in the 5G landscape as enhanced positioning service area. For this, 5G also features interesting capabilities to support a cost-efficient deployment of local networks or private networks dedicated to positioning (e.g. local overlay, either static or mobile, in which it is supported by nodes on vehicles or on UAVs). For instance, with 5G, a Mobile Network Operator or smart city could invest in local infrastructures to enhance GNSS in addressing specific needs where and when needed by customers, for instance:

- enhanced coverage in terms of robustness, accuracy or availability, in e.g. smart cities aiming at enhanced service in some places with high commercial potential, temporary coverage of special events, or during public work in deep urban canyons to enhance machine control capabilities;
- enhanced secure positioning/waypointing or bootstrapping of the UE, thanks to distance bounding and secure time transfer over 5G, e.g. along a road, where the overlay would act as a gantry to control GNSS-enabled positioning.
 
In addition, with the potential advent of the so-called 5G non-terrestrial networks (e.g. UAVs, HAPS, LEO satellites), one could also envisage to use such 5G signals in a wide area or even a global coverage scenario. This landscape carries multiple opportunities to foster the use of GNSS as a key enabler to 5G positioning capabilities, for which a proof-of-concept is required, this could be done using an MIMO SDR as a starting point. 
 
The proposed activity has as its main objective a proof of concept of a hybrid positioning system
using GNSS with 5G TDoA/angular measurements in ad-hoc overlay, aiming to enhance local
GNSS capabilities. This will include several first-of-a-kind technical achievements, e.g:

• GNSS-disciplined 5G signals and positioning nodes;
• hybrid positioning algorithms involving GNSS, 5G-TDoA/Angular measurements and dead-reckoning;
• bootstrapping of GNSS functions with 5G.
   

The tasks to be performed will include:

• selection and consolidation of targeted use cases for proof-of-concept;
• system  definition and preliminary design of a test-bed (which is to include: positioning nodes disciplined on GNSS, enablers for TDoA and Angular measurements, SDR for the UE, hybrid positioning algorithms and reference trajectory mechanism);
• development of the breadboards for the user equipment (UE) and positioning nodes using SDR (the latter disciplined to GNSS signals), including the UE algorithms; 
• validation and fine tuning of the algorithms and concept in non-real time;
• implementation of the most suitable concepts for the UE’s SDR, if possible in real time, and validation with laboratory tests;
• demonstration of performance through field trials.

The main results of the activity will provide:

• breadboards constituent of the testbed  and associated data package; 
• output data from field trials and benchmark with off-the-shelf GNSS solutions.