What is RLM in 5G?

5G NR Radio Link Monitoring (RLM)

When a UE is connected to the network, it requires to continuously monitor the Radio link between the base station and himself for reliable communication, the process is know as Radio Link Monitoring (RLM).

The UE monitor’s the downlink link quality based on the reference signal to measure the downlink radio link quality for the serving cell.


In 5G NR, Radio Link Monitoring is applicable for both Standalone ( SA ) and Non-standalone ( NSA ) architecture. UE performs RLM on active DL BWP of the Primary serving cell (PCell) of the Master Cell Group (MCG). If the UE is configured with a Secondary Cell Group (SCG), then the UE also monitors downlink radio link quality on the active DL BWP of the Primary SCG Cell (PSCell)

  • UE monitoring PCell in SA NR, NR-DC and NE-DC operation mode
  • It monitor PSCell in NR-DC and EN-DC operation mode

Continue reading: 5G NR Radio Link Monitoring - RLM - Techplayon