Patent ID: 7995582

Claim:
A mobile communication system including at least one mobile terminal, a plurality of base stations, and a radio network control apparatus, the at least one mobile terminal transmitting a first negative acknowledgment to any one of said plurality of base stations upon detection of an error in received data, said any one of said plurality of base stations retransmitting the data concerned upon receipt of the first negative acknowledgment, said radio network control apparatus controlling said any one of said plurality of base stations, wherein said at least one mobile terminal includes a first negative acknowledgment transmission unit that attaches, to the first negative acknowledgment, cell identification information of a cell from which the received data is received upon detection of the error in the received data, each of said plurality of base stations includes a determination unit that determines whether said cell identification information in said first negative acknowledgment includes only cell identification information of a cell managed by said any one of said plurality of base stations, and a second negative acknowledgment transmission unit that transmits a second negative acknowledgment to said radio network control apparatus if said determination unit determines that said cell identification information in said first negative acknowledgment includes cell identification information of a cell other than a cell managed by said any one of said plurality of base stations in addition to a cell managed by said any one of said plurality of base stations, said second negative acknowledgment containing a data number for specifying the received data having said error detected by said at least one mobile terminal and said cell identification information, and said radio network control apparatus includes a decision unit that decides which of said plurality of base stations are to perform data retransmission on the basis of the cell identification information in said second negative acknowledgment, and a data retransmission request unit that transmits a data retransmission request including a data retransmission time to said decided ones of said plurality of base stations such that said decided ones of said plurality of base stations that receive the data retransmission request from said radio network control apparatus implements data retransmission synchronously based on the received data retransmission time.