15.5.2.1 General

Mobility Robustness Optimisation aims at detecting and enabling correction of following problems:

• Connection failure due to intra-system or inter-system mobility;
• Inter-system Unnecessary HO (too early inter-system HO from NR to E-UTRAN with no radio link failure);
• Inter-system HO ping-pong;
• PSCell change failure;
• Inter-system voice fallback failure;
• Fast MCG recovery failure or a sub-optimal Fast MCG recovery.

MRO provides means to distinguish the above problems from NR coverage related problems and other problems, not related to mobility.

For detection of a sub-optimal successful handovers, MRO additionally enables observability of:

• Successful HO due to intra-NR mobility;
• Successful HO due to inter-RAT mobility.

For detection of a sub-optimal successful PSCell addition/change, MRO additionally enables observability of:

• Successful PSCell addition/change.