5G Radio Working Group (RAN3) R17 Key Work Highlights

RAN3 Release 17 focuses on major evolutions in 5G (NR), bringing enhancements to key architectures such as native multi-access edge computing (MEC) support, the introduction of reduced-capacity RedCap for IoT, enhanced sidechains, positioning and MIMO, and increased support for new frequency bands (up to 71 GHz) and non-terrestrial NTN. All of these improvements are built upon core network function evolution to enhance spectrum efficiency and device power saving, enabling broader 5G applications.

I. Key Features of RAN3 in Release-17

• IAB Function Enhancements—Improved resource reuse, topology robustness, and routing options between IAB parent and child links.
• NTN (Non-Terrestrial Network) Architecture—System architecture supports integration of satellite/HAP with terrestrial 5G (NR).
• NPN (Non-Public Network) Enhancements and Edge Computing Integration Support.

II. Key Technical Details and System Integration of RAN3

2.1 Enhanced IAB (Integrated Access and Backhaul) Technology

Resource Reuse: Rel-17 defines additional mechanisms that enable IAB nodes to allocate resources more flexibly between access (to UE) and backhaul (to child IAB nodes) based on existing scheduling. Specifically:

• Updating F1/Xn internal signaling between the parent node and the IAB-DU/MT.
• Achieving robust path management and rerouting—the IAB control plane (IAB-CU) must be able to reallocate provider relationships in the event of link failure.
• Topology and Routing: Support for semi-static routing table updates and enhanced bearer mapping; vendors need to test congestion/priority rules for backhaul and access traffic.

2.2 NTN Architecture

GW and NG-RAN Integration: Rel-17 defines NTN Stage 2/Stage 3 architectural changes to support satellite link features end-to-end. Implementers must coordinate with the CN (SA/CT) to support PDU sessions and mobility differences (such as longer handover times due to GEO/LEO satellite movement).

Timing and Synchronization: NTN nodes typically require GNSS/time distribution (or alternative time synchronization) and specific handling of timing advance and HARQ timers within the RAN architecture is necessary.