Technique for handling radio link failure in a communication network

Art for dealing with a radio link obstacle in a communication network (10) is provided. One embodiment of a method according to this art is provided with the following. A step holding radio link obstacle information, A step which receives re-connection information after a user's unit (UE) is re-connected to a communication network, A step which takes correlation with radio link obstacle information and re-connection information, and obtains a correlation result. Radio link obstacle information is provided with the following. An identifier of a user's unit (UE) which has received a radio link obstacle, At least one of reference information which shows a cell (C1) which provided service to a user's unit (UE) before detecting a time stamp and a radio link obstacle which show when a radio link obstacle was detected. Re-connection information contains an identifier of a user's unit (UE) which has received a radio link obstacle and was re-connected.