Wireless communication method, wireless communication system, base station, and wireless station
A wireless communication method including: when a wireless station has dual connectivity to a first base station that is a primary base station and a second base station that is a secondary base station and when a handover of the primary base station is to be performed from the first base station to a third base station, transmitting from the first base station to the third base station a first signal requesting the handover, when the third base station makes a determination not to change the secondary base station based on the first signal, transmitting from the third base station to the second base station a second signal indicating the determination and to the first base station a third signal indicating the determination, and performing the handover based on the third signal without transferring a connection between the wireless station and the second base station to the first base station.
1. A wireless communication method comprising:
transmitting, by a first base station that is a primary base station for a wireless station, to a third base station, a first signal requesting a switching of the primary base station to the third base station when the wireless station has a multiple connection and when a handover of the wireless station from the first base station to the third base station is to be performed, wherein
the multiple connection comprises at least a first connection and a second connection, and
the first connection is a connection between the wireless station and the first base station, and
the second connection is a connection between the wireless station and a second base station that is a secondary base station for the wireless station;
transmitting, by the third base station, to the second base station a second signal requesting that the second connection is to be maintained when the third base station receives the first signal and determines that the second connection is to be maintained;
transmitting, by the second base station, to the third base station a third signal indicating a positive response to the second signal when the second base station receives the second signal and determines that the second connection is to be maintained;
transmitting, by the third base station, to the first base station a fourth signal indicating that the second connection is to be maintained when the third base station receives the third signal; and
performing, by the first base station and the third base station, the handover and the switching without transferring the second connection to neither the first base station nor the third base station.
2. The wireless communication method according to claim 1 , wherein the first signal includes an identifier of the second base station.
3. The wireless communication method according to claim 1 , wherein
transmitting, by the second base station, to the third base station a fifth signal indicating a negative response to the second signal when the second base station receives the second signal and determines that the second connection is not to be maintained;
transmitting, by the third base station, to the first base station a sixth signal indicating that the second connection is not to be maintained when the third base station receives the fifth signal; and
performing, by the first base station and the third base station, the handover and the switching with transferring the second connection to the third base station.
4. A wireless communication system comprising:
a wireless station;
a first base station;
a second base station; and
a third base station, wherein
the first base station that is a primary base station for the wireless station is configured to transmit to the third base station a first signal requesting a switching of a primary base station to the third base station when the wireless station has a multiple connection and when a handover of the wireless station from the first base station to the third base station is to be performed, wherein
the multiple connection comprises at least a first connection and a second connection, and
the first connection is a connection between the wireless station and the first base station, and
the second connection is a connection between the wireless station and the second base station that is a secondary base station for the wireless station,
the third base station is configured to transmit to the second base station a second signal requesting that the second connection is to be maintained when the third base station receives the first signal and determines that the second connection is to be maintained,
the second base station is configured to transmit to the third base station a third signal indicating a positive response to the second signal when the second base station receives the second signal and determines that the second connection is to be maintained,
the third base station is configured to transmit to the first base station a fourth signal indicating that the second connection is to be maintained when the third base station receives the third signal, and
the first base station and the third base station are configured to perform the handover and the switching without transferring the second connection to neither the first base station nor the third base station.
5. The wireless communication system according to claim 4 , wherein
the second base station is configured to transmit to the third base station a fifth signal indicating a negative response to the second signal when the second base station receives the second signal and determines that the second connection is not to be maintained,
the third base station is configured to transmit to the first base station a sixth signal indicating that the second connection is not to be maintained when the third base station receives the fifth signal, and
the first base station and the third base station are configured to perform the handover and the switching with transferring the second connection to the third base station.
6. A second base station comprising:
a communication unit; and
a controller, wherein
the communication unit is configured to receive a second signal requesting that a second connection is to be maintained, the second signal being transmitted from a third base station as a result of determining, by the third base station, that the second connection is to be maintained when a wireless station has a multiple connection and when a handover of the wireless station from a first base station that is a primary base station for the wireless station to the third base station is to be performed, the multiple connection comprising at least a first connection and the second connection, and the first connection being a connection between the wireless station and the first base station, and the second connection being a connection between the wireless station and the second base station that is a secondary base station for the wireless station,
the controller is configured to determine whether the second connection is to be maintained when the controller receives the second signal via the communication unit, and
the communication unit is configured to transmit to the third base station a third signal indicating a positive response to the second signal when the controller determines that the second connection is to be maintained.
7. The second base station according to claim 6 , wherein
the communication unit is configured to transmit to the third base station a fifth signal indicating a negative response to the second signal when the controller determines that the second connection is not to be maintained.
8. A third base station comprising:
a communication unit; and
a controller, wherein
the communication unit is configured to receive a first signal requesting a switching of a primary base station for a wireless station to the third base station when the wireless station has a multiple connection and when a handover of the wireless station from a first base station that is the primary base station to the third base station is to be performed, the multiple connection comprising at least a first connection and a second connection, and the first connection being a connection between the wireless station and the first base station, and the second connection being a connection between the wireless station and a second base station that is a secondary base station for the wireless station,
the controller is configured to determine whether the second connection is to be maintained when the controller receives the first signal via the communication unit,
the communication unit is configured to transmit to the second base station a second signal requesting that the second connection is to be maintained when the controller determines that the second connection is to be maintained,
the communication unit is configured to transmit a fourth signal indicating that the second connection is to be maintained when the communication unit receives a third signal indicating a positive response to the second signal, the third signal being transmitted from the second base station as a result of determining, by the second base station, that the second connection is to be maintained, and
the controller is configured to perform the handover and the switching without transferring the second connection to neither the first base station nor the third base station.
9. The third base station according to claim 8 , wherein
the communication unit is configured to transmit a sixth signal indicating that the second connection is not to be maintained when the communication unit receives a fifth signal indicating a negative response to the second signal, the fifth signal being transmitted from the second base station as a result of determining, by the second base station, that the second connection is not to be maintained, and
the controller is configured to perform the handover and the switching with transferring the second connection to the third base station.