초록 ▼

A mobile communication system enables data reception in correct order, with regard to a reversed data order caused by a route change in data transfer from a source base station to a target base station and in direct transmission from a gateway to a target base station is provided. In the mobile comm

A mobile communication system enables data reception in correct order, with regard to a reversed data order caused by a route change in data transfer from a source base station to a target base station and in direct transmission from a gateway to a target base station is provided. In the mobile communication system, at the time of handover processing performed accompanying a movement of the user equipment from the source base station to the target base station, the source base station transfers to the target base station, a part of packet data not yet transmitted to the user equipment, among packet data received from the upper-level device, and when transferring the part of packet data, the source base station assigns transfer start information, indicating a start of transfer, to a header in a top packet of the untransmitted packet data.

대표청구항 ▼

1. A mobile communication system comprising: a gateway device;a source base station and a target base station; anduser equipment configured to receive packet data of packets sequentially transmitted from the gateway device via either of the source base station and the target base station; whereinat

1. A mobile communication system comprising: a gateway device;a source base station and a target base station; anduser equipment configured to receive packet data of packets sequentially transmitted from the gateway device via either of the source base station and the target base station; whereinat the time of handover processing performed accompanying a movement of the user equipment from the source base station to the target base station, the source base station transfers to the target base station, packet data received from the gateway device, but not yet transmitted to the user equipment, and when transferring the packet data to the target base station, the source base station assigns first transfer start information, which indicates a start of transfer, to a header in a leading packet of the packet data untransmitted to the user equipment, and whereinthe gateway device assigns second transfer start information to a header in a leading packet of packet data, which are to be directly transmitted from the gateway device to the target base station, andbased on the first and second transfer start information in respective leading packets of the packet data transmitted from the source base station and the gateway device, the target base station recognizes a transmission order of packet data, so as to transmit the packet data received from the source base station and the gateway device in the recognized transmission order to the user equipment. 2. The mobile communication system according to claim 1, wherein the gateway device assigns transfer order information indicating transmission order to the packet data on a packet-by-packet basis, and on receiving each packet from the source base station and the gateway device, if the target base station has not received a packet corresponding to an order earlier than the order of the each received packet obtained from the transfer order information, the target base station preserves the each received packet into a buffer, so as to change reception packet order. 3. The mobile communication system according to claim 2, wherein the target base station recognizes the second transfer start information assigned to the leading packet of the packet data received from the gateway device, and based on the recognized second transfer start information, identifies a last packet of the packet data to be transferred from the source base station. 4. The mobile communication system according to claim 2, wherein the target base station identifies an unreceived packet, based on the transfer order information assigned to the packet data received from the source base station and the upper-level unit. 5. The mobile communication system according to claim 2, wherein the transfer order information is a sequence number in a packet GTP-U header, andthe target base station transfers to the user equipment each data packet received from the source base station and the upper-level unit, by making a sequence number in a PDCP header correspond to the sequence number in the GTP-U header of the each received packet data. 6. The mobile communication system according to claim 5, wherein different tunnel IDs are set respectively between the gateway device and the source base station, and between the gateway device and the target base station, and the gateway device sets the sequence number in the each packet GTP-U header so as to maintain continuity over the different tunnel IDs. 7. The mobile communication system according to claim 1, wherein transfer order information indicating transmission order is assigned to each packet by the gateway device, andat the time of handover processing performed accompanying a movement of the user equipment from the source base station to the target base station, the gateway device and the source base station add transfer order information, which is assigned to leading packets respectively having the assigned transfer start information, to the entire packet data, which are transferred to the target base station from the source base station and the gateway device. 8. A mobile communication method in a mobile communication system including a gateway device, a source base station and a target base station, and user equipment configured to receive packet data of packets sequentially transmitted from the gateway device via either of the source base station and the target base station, the mobile communication method comprising: at the time of handover processing performed accompanying a movement of the user equipment from the source base station to the target base station, transferring by the source base station, to the target base station, packet data received from the gateway device, but not yet transmitted to the user equipment;when transferring the packet data to the target base station, assigning by the source base station, first transfer start information, which indicates a start of transfer, to a header in a leading packet of the packet data untransmitted to the user equipment;by the gateway device, assigning the transfer start information to a header in the leading packet of the packet data, which are to be directly transmitted to the target base station; andbased on the first and second transfer start information in respective leading packets of the packet data transmitted from the source base station and the gateway device, recognizing by the target base station, a packet data order, so as to transmit the packet data received from the source base station and gateway device in the recognized packet order to the user equipment.