Radio communication system, radio station, radio terminal, communication control method, and non-transitory computer readable medium
A radio terminal ( 3 ) can perform carrier aggregation using a first cell ( 10 ) of a first radio station ( 1 ) and a second cell ( 20 ) of a second radio station ( 2 ). The first radio station ( 1 ) or the second radio station ( 2 ) transmits constraint information to the radio terminal ( 3 ). The constraint information contains an information element necessary to specify a reception constraint and/or transmission constraint related to the first cell ( 10 ) and/or the second cell ( 20 ) when the carrier aggregation is performed. The reception/transmission constraint is a constraint related to downlink signal reception/uplink signal transmission by the radio terminal over one or more subframe periods of the primary cell ( 10 ) and the secondary cell ( 20 ). It is thus, for example, possible to contribute to reduction in wasteful power consumption in the radio terminal in the carrier aggregation of a plurality of cells served by different radio stations.
1. A radio communication system comprising:
a first radio station configured to serve a first cell;
a second radio station configured to serve a second cell; and
a radio terminal configured to support Dual Connectivity using the first and second cells, wherein
the first radio station is configured to send first constraint information to the second radio station and receive second constraint information from the second radio station,
the first radio station is further configured to transmit uplink constraint information to the radio terminal, wherein
the first constraint information is a constraint related to at least one of uplink signal transmission by the radio terminal and downlink signal transmission by the first radio station in the first cell,
the second constraint information is a constraint related to at least one of uplink signal transmission by the radio terminal and downlink signal transmission by the second radio station in the second cell,
the uplink constraint information contains an information element for deriving transmission constraint in a case where the Dual Connectivity using the first and second cells is performed,
the transmission constraint is a constraint related to uplink signal transmission by the radio terminal over one or more subframe periods and indicates a first timing in which uplink signal transmission in the first cell is allowed,
a second timing in which uplink signal transmission in the second cell is allowed is set so that the first timing and the second timing are not overlapped, and
the radio terminal is configured to perform uplink transmission in the first cell and the second cell based on the uplink constraint information.
2. The radio communication system according to claim 1 , wherein the uplink constraint information contains an information element for deriving start of the first timing.
3. The radio communication system according to claim 1 , wherein the second cell is a second type of cells which is different from a first type of cells of the first cell.
4. A radio terminal comprising:
a memory storing instructions; and
at least one processor configured to process the instructions to:
support Dual Connectivity using a first cell served by a first radio station and a second cell served by a second radio station; and
receive uplink constraint information from the first radio station, wherein
the uplink constraint information contains an information element for deriving transmission constraint in a case where the Dual Connectivity using the first and second cells is performed,
the transmission constraint is a constraint related to uplink signal transmission by the radio terminal over one or more subframe periods and indicates a first timing in which uplink signal transmission in the first cell is allowed,
a second timing in which uplink signal transmission in the second cell is allowed is set so that the first timing and the second timing are not overlapped, and
the radio terminal is configured to perform uplink transmission in the first cell and the second cell based on the uplink constraint information.
5. The radio terminal according to claim 4 , wherein the uplink constraint information contains an information element for deriving start of the first timing.
6. The radio terminal according to claim 4 , wherein the second cell is a second type of cells which is different from a first type of cells of the first cell.
7. A first radio station configured to serve a first cell, comprising:
a memory storing instructions; and
at least one processor configured to process the instructions to:
support Dual Connectivity using the first cell and a second cell served by a second radio station;
send first constraint information to the second radio station;
receive second constraint information from the second radio station; and
transmit uplink constraint information to the radio terminal, wherein
the first constraint information is a constraint related to at least one of uplink signal transmission by the radio terminal and downlink signal transmission by the first radio station in the first cell,
the second constraint information is a constraint related to at least one of uplink signal transmission by the radio terminal and downlink signal transmission by the second radio station in the second cell,
the uplink constraint information contains an information element for deriving transmission constraint in a case where the Dual Connectivity using the first and second cells is performed,
the transmission constraint is a constraint related to uplink signal transmission by the radio terminal over one or more subframe periods and indicates a first timing in which uplink signal transmission in the first cell is allowed, and
the transmission constraint causes the radio terminal to set a second timing in which uplink signal transmission in the second cell is allowed so that the first timing and the second timing are not overlapped.
8. The first radio station according to claim 7 , wherein the uplink constraint information contains an information element for deriving start of the first timing.
9. The first radio station according to claim 7 , wherein the first cell is a first type of cells which is different from a second type of cells of the second cell.
10. A communication control method in a radio terminal, comprising:
supporting Dual Connectivity using a first cell served by a first radio station and a second cell served by a second radio station; and
receiving uplink constraint information from the first radio station, wherein
the uplink constraint information contains an information element for deriving transmission constraint in a case where the Dual Connectivity using the first and second cells is performed,
the transmission constraint is a constraint related to uplink signal transmission by the radio terminal over one or more subframe periods and indicates a first timing in which uplink signal transmission in the first cell is allowed, and
a second timing in which uplink signal transmission in the second cell is allowed is set so that the first timing and the second timing are not overlapped, and the communication control method further comprises:
performing uplink transmission in the first cell and the second cell based on the uplink constraint information.
11. A communication control method in a first radio station, comprising:
serving a first cell;
supporting Dual Connectivity using the first cell and a second cell served by a second radio station;
sending first constraint information to the second radio station;
receiving second constraint information from the second radio station; and
transmitting uplink constraint information to the radio terminal, wherein
the first constraint information is a constraint related to at least one of uplink signal transmission by the radio terminal and downlink signal transmission by the first radio station in the first cell,
the second constraint information is a constraint related to at least one of uplink signal transmission by the radio terminal and downlink signal transmission by the second radio station in the second cell,
the uplink constraint information contains an information element for deriving transmission constraint in a case where the Dual Connectivity using the first and second cells is performed,
the transmission constraint is a constraint related to uplink signal transmission by the radio terminal over one or more subframe periods and indicates a first timing in which uplink signal transmission in the first cell is allowed,
the transmission constraint causes the radio terminal to set a second timing in which uplink signal transmission in the second cell is allowed so that the first timing and the second timing are not overlapped.