Patent ID: 8588180

Claim:
A mobile communication system having a base station that manages a cell; and a mobile station that performs a handover from a source cell to a target cell as said mobile station moves, characterized in that said mobile station measures reception quality levels of individual peripheral cells of said source cell and transmits information of the measured reception quality levels of the individual peripheral cells to a source base station that manages said source cell, said source base station selects a group of cells that are to be handed over, based on the information of reception quality levels of the individual peripheral cells that is received from said mobile station, and transmits information of handover ready completion cells that are ready for handover in the selected group of cells to said mobile station, and said mobile station selects a target cell that is to be handed over, based on the information of handover ready completion cells that is received from said source base station, and on the information of reception quality levels of the individual peripheral cells at that time, wherein said source base station selects a group of cells that are to be handed over, based on the information of reception quality levels of the individual peripheral cells that is received from said mobile station, and on the information of cells registered in a cell black list, transmits a handover ready request message to a group of peripheral base stations that manage the selected group of cells, and creates information of handover ready completion cells based on a request positive reply message, that is received from said group of peripheral base stations, to the handover ready request message, said source base station registers information of cells that have not received said request positive reply message from said group of peripheral base stations in said cell black list, and said source base station deletes information of cells from said cell black list if the information of cells that have received said request positive reply message from said group of peripheral base stations has been registered in said cell black list, wherein, for a cell for which information is registered in said cell black list, a value of a handover ready request avoidance counter is checked, and if the value of the handover ready request avoidance counter is equal to a threshold value, the value of the handover ready request avoidance counter for the cell is cleared and the cell is selected as a cell to be handed over, and if the value of the handover ready request avoidance counter is less than the threshold value, the value of the handover ready request avoidance counter for the cell is incremented and the cell is excluded from the cells to be handed over.