GADGET Project has the objective to design and implement two User Equipment (UE) and one gNodeB compliant with the 5G release 16 or above to demonstrate the direct access to non-terrestrial-network (NTN) based on a satellite access. These equipment will be integrated in an end-to-end demonstration configuration based on emulated and live satellite access. This last is represented by the actual access to Athena/Fidus satellite operating in Ka frequency band and positioned in geo-stationary orbit position at 38° E.
In the development of the UEs and the gNodeB, more attention is on the protocol stack implementation in line with the foreseen 5G standard release and starting as base point from an Open-Source software environment. In the implementation of the E2E demonstrator also the simulator of the Core Network will be implemented to perform the foreseen performance and operative tests.
The challenge of the activity is twofold: the development of the actual gNodeB and UE both compliant with the 5G Release 17 standard based on New Radio (NR) NTN enhancements; then, to set-up and to execute a complete and significant demonstration based on a real direct satellite access. This last will give the opportunity to experience all the characteristics with its impairments in accessing an actual satellite. A laboratory emulation will support the test and verification phase in advance to the demonstration.
A 5G satellite system is beneficial for various reasons and different use cases, especially broadband communications in underserved areas by terrestrial TLC infrastructures, as well as offering an international and global coverage. The 5G satellite network will lead to a reduction of digital divide, and will offer broadband connectivity at lower costs than ground infrastructures, especially in underserved or developing areas such as extended areas in Africa or south-east Asia. Another beneficial of the 5G NTN is that it will facilitate and speed-up the actual integration between satellite and terrestrial networks providing an actual global access to Internet to the worldwide users.
The system includes a 5G-compatible gNodeB and UE developed in an open-source approach and running on COTS hardware compatible with the 5G Release 16 and upgradable in an easy way to future new release currently in development.
The baseline is the srsRAN software suite (https://www.srslte.com/), which has been selected due to its flexible capabilities and easy expandability.
The gNodeB and UE are easily interfaced with typical VSAT for the satellite access and can be also interfaced and utilised towards other NTN access networks. A channel emulator is utilised in parallel to the actual satellite access for laboratory tests. It is providing RF interfaces and Up/Down conversion from L-Band to Ka-Band, allowing to emulate the channel in the bands of interest before access the satellite during the demonstration campaign.
The architecture is defined below.
two UEs, one nomadic and one fixed, can establish bidirectional connections with a gNB through a satellite transponder.
the testbed includes both access and non-access stratum capabilities.
the testbed allows analysis of E2E performances through predefined sensible KPIs.
The figure shows the system architecture based off the 5G basic blocks. A GUI for monitoring the KPI has been added to the system allowing:
Configuration of the main functionalities that impact the NTN performances.
Monitoring and reporting of the KPIs of interest.
Traffic generation, to emulate the traffic generated by the applications.
The overall network architecture, the protocol stack, the QoS traffic management and the UE/Satellite characteristics are referenced from 3GPP standards, according with the scenario defined in the statement of work.
The Project is organised in two phases:
Phase 1 – 6 months;
Phase 2 – 18 months.
The Phase 1 was successfully completed in July 2022 with the Preliminary Design Review (PDR) milestone.
The Phase 2 is just started. The next Project Milestones are as follows:
Critical Design Review (CDR) – December 2022
Qualification Review – May 2023
Final Review – December 2023
The HW and SW platforms have been defined, the architectural solution has been identified, and the CDR is under preparation.