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Building 5G RedCap Support in Collaboration with OCUDU

Mohit Bidikar and Poonam Yadav

5GRedCapOCUDU

Project Overview

We are building 5G RedCap support in OCUDU through open-source code contributions, working closely with the OCUDU team on implementation, review and real-device validation.

Follow the collaboration and technical discussion in OCUDU work item #812: Initial RedCap support and EM8695 interoperability testing.

Implemented So Far

Three contributions have been merged into OCUDU:

  • RedCap message decoding: recognising RedCap initial-access messages at the MAC layer, with validation and regression tests.
  • Device identity propagation: carrying the RedCap indication through the distributed unit (DU) and central unit (CU).
  • Broadcast and radio configuration: an opt-in Release-17 RedCap profile with access controls and initial bandwidth parts up to 20 MHz.

We have also implemented capability-aware bearer limits and controlled RedCap access, which remains under review. This includes appropriate PDCP/RLC sequence-number settings, bearer-count limits and handling of capabilities during mobility procedures.

Next Steps

Following the discussion with OCUDU maintainers, we plan to:

  • Add the NGAP RedCap indication, allowing the core network to identify RedCap devices.
  • Extend F1AP Served Cell Information with RedCap broadcast information.
  • Complete review of the access implementation and expand regression and mobility testing, including automatic key refresh.

Longer-term directions include bandwidth-part handling for RedCap in wider-bandwidth cells. We are also interested in exploring AI-RAN contributions involving ML-based RAN optimisation and GPU acceleration as the RedCap work progresses.