5G Radio Link Failure Causes | 5G Radio Link Failure Phases

This page describes 5G Radio Link Failure Causes and phases. It mentions 5G Radio Link Failure Phases of 5G UE.

Following are the possible causes of radio link failure in wireless system.
• Failure at lower layers of stack i.e. at RF or physical layer due to higher frequency offset or time offset, poor carrier to interference conditions on the channels exchanged between UE and NB (i.e. base station). Poor C/I occurs mainly due to power related issues.
• Radio link failure during handover procedure or cell re-selection procedure.

As shown in the figure-1, two phases are associated with radio link failure in 5G wireless technology.
➨UE enters into first phase as soon as radio issue is being detected. This leads to radio link failure detection with no UE based mobility. UE does not recover during timer T1.
➨UE enters in the second phase after handover failure or upon detection of radio link failure. UE enters into RRC_IDLE state and UE based mobility i.e. cell selection occurs. In this phase, UE avoids going through RRC_IDLE by staying in RRC_CONNECTED state. To do so, UE accesses 5G cell via random access procedure.

Also refer radio link failure test case>> which explains radio link failure in GSM at UE/network side at layer-1 and layer-2.

Reference: TS V5G.300