Mobile communication system

2:

• A mobile communication system including at least a plurality of cells configured to perform radio communication with a movable user equipment device, wherein
• said plurality of cells include a cell configured to perform coordinated communication to perform radio communication with said user equipment device in a coordinated manner with another cell,
• among said plurality of cells, a serving cell that controls said user equipment device configures a detection target cell set and notifies said user equipment device of said detection target cell set that has been configured, said detection target cell set being a collection of cells to be subjected to a process of detecting, by said user equipment device, whether or not radio communication is allowed,
• said serving cell configures a subset composed of a part or the whole of cells in a coordination target cell set, said coordination target cell set being a collection of cells to be subjected to a process of detecting whether or not said coordinated communication is allowed among the cells in a coordination-enabled cell set, said coordination-enabled cell set being a collection of cells to become candidates on which said user equipment device performs a process of detecting whether or not said coordinated communication is allowed among the cells in said detection target cell set, and
• said user equipment device measures a channel-state information reference signal of the cell in said subset and reports a measurement result to said serving cell when being notified of said subset.