Radio communication system, radio station, radio terminal, communication control method, and non-transitory computer readable medium
View Patent ↗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 that serves a first cell;
a second radio station that serves a second cell; and
a radio terminal configured to perform Dual Connectivity using the first and second cells, wherein
the first radio station is configured to transmit first constraint information on the first cell and second constraint information on the second cell to the radio terminal,
the first constraint information contains a first information element for specifying a first transmission constraint related to the first cell when the Dual Connectivity is performed,
the second constraint information contains a second information element for specifying a second transmission constraint related to the second cell when the Dual Connectivity is performed,
each of the first and second transmission constraints includes a period related to uplink signal transmission by the radio terminal,
the first radio station is configured to transmit information for instructing the radio terminal to start the period in the first cell, and
the second radio station is configured to transmit information for instructing the radio terminal to start the period in the second cell.
2. The radio communication system according to claim 1 , wherein each of the first and second transmission constraints includes a constraint indicating that the radio terminal is prohibited from transmitting an uplink signal.
3. The radio communication system according to claim 1 , wherein the first information element explicitly or implicitly indicates a period in which the first transmission constraint is not imposed, and the second information element explicitly or implicitly indicates a period in which the second transmission constraint is not imposed.
4. The radio communication system according to claim 1 , wherein the second information element explicitly or implicitly indicates, as an information element for specifying the second transmission constraint related to the second cell, at least one of a reception period, a non-reception period, a reception constraint, a transmission period, a non-transmission period, and a transmission constraint for the radio terminal in the first cell.
5. The radio communication system according to claim 1 , wherein each of the first and second information elements explicitly or implicitly indicates at least one of:
(a) a period in which transmission of an uplink signal is prohibited;
(b) a period in which the uplink signal is transmitted; and
(c) a period in which transmission of the uplink signal is permitted.
6. The radio communication system according to claim 1 , wherein the radio terminal is configured to perform a transmitting operation in accordance with at least one of the first and second transmission constraints when the radio terminal receives at least one of the information for instructing the radio terminal to start the period in the first cell and the information for instructing the radio terminal to start the period in the second cell.
7. The radio communication system according to claim 1 , wherein the second radio station is further configured to transmit the second constraint information on the second cell to the first radio station.
8. The radio communication system according to claim 1 , wherein
the first transmission constraint for the first cell and the second transmission constraint for the second cell are configured so that a start point of a transmission period in the second cell is independent of a start point of a transmission period in the first cell,
the transmission period in the second cell includes a period in which an uplink signal is transmitted in the second cell or a period in which transmission of the uplink signal in the second cell is permitted, and
the transmission period in the first cell includes a period in which an uplink signal is transmitted in the first cell or a period in which transmission of the uplink signal in the first cell is permitted.
9. A first radio station that serves a first cell, comprising:
a transceiver configured to communicate with a radio terminal; and
at least one processor configured to:
support Dual Connectivity using the first cell and a second cell served by a second radio station; and
transmit first constraint information on the first cell and second constraint information on the second cell to the radio terminal that performs the Dual Connectivity, wherein
the first constraint information contains a first information element for specifying a first transmission constraint related to the first cell when the Dual Connectivity is performed,
the second constraint information contains a second information element for specifying a second transmission constraint related to the second cell when the Dual Connectivity is performed,
each of the first and second transmission constraints includes a period related to uplink signal transmission by the radio terminal,
the transceiver is configured to transmit information for instructing the radio terminal to start the period in the first cell.
10. The first radio station according to claim 9 , wherein each of the first and second transmission constraints includes a constraint indicating that the radio terminal is prohibited from transmitting an uplink signal.
11. The first radio station according to claim 9 , wherein each of the first and second information elements explicitly or implicitly indicates at least one of:
(a) a period in which transmission of an uplink signal is prohibited;
(b) a period in which the uplink signal is transmitted; and
(c) a period in which transmission of the uplink signal is permitted.
12. The first radio station according to claim 9 , wherein the at least one processor is configured to transmit, using the transceiver, the first constraint information and the second constraint information to the radio terminal, the second constraint information being sent from the second radio station.
13. A second radio station that serves a second cell, comprising:
a transceiver configured to communicate with a radio terminal; and
at least one processor configured to:
support Dual Connectivity using a first cell served by a first radio station and the second cell; and
transmit second constraint information on the second cell to the radio terminal via the first radio station, the radio terminal being configured to perform the Dual Connectivity, wherein
the second constraint information contains a second information element for specifying a second transmission constraint related to the second cell when the Dual Connectivity is performed, and is different from first constraint information on the first cell is transmitted from the first radio station to the radio terminal,
the first constraint information contains a first information element for specifying a first transmission constraint related to the first cell,
each of the first and second transmission constraints includes a period related to uplink signal transmission by the radio terminal, and
the transceiver is configured to transmit information for instructing the radio terminal to start the period in the second cell.
14. The second radio station according to claim 13 , wherein the at least one processor is configured to transmit, using the transceiver, another second constraint information on the second cell directly to the radio terminal.
15. A radio terminal comprising:
at least one transceiver configured to communicate with a first radio station and a second radio station; and
at least one processor configured to:
support Dual Connectivity using a first cell served by the first radio station and a second cell served by the second radio station; and
receive, using the at least one transceiver, first constraint information on the first cell and second constraint information on the second cell from the first radio station, wherein
the first constraint information contains a first information element for specifying a first transmission constraint related to the first cell when the Dual Connectivity is performed,
the second constraint information contains a second information element for specifying a second transmission constraint related to the second cell when the Dual Connectivity is performed,
each of the first and second transmission constraints includes a period related to uplink signal transmission by the radio terminal, and
the at least one transceiver is configured to:
receive information for instructing the radio terminal to start the period in the first cell from the first radio station, and
receive information for instructing the radio terminal to start the period in the second cell from the second radio station.
16. The radio terminal according to claim 15 , wherein each of the first and second transmission constraints includes a constraint indicating that the radio terminal is prohibited from transmitting an uplink signal.
17. The radio terminal according to claim 15 , wherein each of the first and second information elements explicitly or implicitly indicates at least one of:
(a) a period in which transmission of an uplink signal is prohibited;
(b) a period in which the uplink signal is transmitted; and
(c) a period in which transmission of the uplink signal is permitted.
18. The radio terminal according to claim 15 , wherein the at least one processor is configured to perform a transmitting operation in accordance with at least one of the first and second transmission constraints when the radio terminal receives at least one of the information for instructing the radio terminal to start the period in the first cell and the information for instructing the radio terminal to start the period in the second cell.
19. A communication control method in a first radio station that serves a first cell, the communication control method comprising:
transmitting first constraint information on the first cell and second constraint information on a second cell served by a second radio station to a radio terminal that performs Dual Connectivity using the first cell and the second cell, wherein
the first constraint information contains a first information element for specifying a first transmission constraint related to the first cell when the Dual Connectivity is performed,
the second constraint information contains a second information element for specifying a second transmission constraint related to the second cell when the Dual Connectivity is performed,
each of the first and second transmission constraints includes a period related to uplink signal transmission by the radio terminal, and
the communication control method further comprises transmitting information for instructing the radio terminal to start the period in the first cell.
20. The communication control method according to claim 19 , wherein each of the first and second transmission constraints includes a constraint indicating that the radio terminal is prohibited from transmitting an uplink signal.
21. The communication control method according to claim 19 , wherein each of the first and second information elements explicitly or implicitly indicates at least one of:
(a) a period in which transmission of an uplink signal is prohibited;
(b) a period in which the uplink signal is transmitted; and
(c) a period in which transmission of the uplink signal is permitted.
22. A communication control method in a second radio station that serves a second cell, the communication control method comprising:
transmitting second constraint information on the second cell to a radio terminal via a first radio station, the radio terminal being configured to perform Dual Connectivity using the second cell and a first cell served by the first radio station, wherein
the second constraint information contains a second information element for specifying a second transmission constraint related to the second cell when the Dual Connectivity is performed, and is different from first constraint information on the first cell, transmitted from the first radio station to the radio terminal,
the first constraint information contains a first information element for specifying a first transmission constraint related to the first cell,
each of the first and second transmission constraints includes a period related to uplink signal transmission by the radio terminal, and
the communication control method further comprises transmitting information for instructing the radio terminal to start the period in the second cell.
23. A communication control method in a radio terminal, the communication control method comprising:
performing Dual Connectivity using a first cell served by a first radio station and a second cell served by a second radio station; and
receiving first constraint information and second constraint information from the first radio station, wherein
the first constraint information contains a first information element for specifying a first transmission constraint related to the first cell when the Dual Connectivity is performed,
the second constraint information contains a second information element for specifying a second transmission constraint related to the second cell when the Dual Connectivity is performed,
each of the first and second transmission constraints includes a period related to uplink signal transmission by the radio terminal, and
the communication control method further comprises:
receiving information for instructing the radio terminal to start the period in the first cell from the first radio station; and
receiving information for instructing the radio terminal to start the period in the second cell from the second radio station.
24. The communication control method according to claim 23 , wherein each of the first and second transmission constraints includes a constraint indicating that the radio terminal is prohibited from transmitting an uplink signal.
25. The communication control method according to claim 23 , wherein each of the first and second information elements explicitly or implicitly indicates at least one of:
(a) a period in which transmission of an uplink signal is prohibited;
(b) a period in which the uplink signal is transmitted; and
(c) a period in which transmission of the uplink signal is permitted.
26. The communication control method according to claim 23 , wherein the performing Dual Connectivity includes performing a transmitting operation in accordance with at least one of the first and second transmission constraints when the radio terminal receives at least one of the information for instructing the radio terminal to start the period in the first cell and the information for instructing the radio terminal to start the period in the second cell.
27. A non-transitory computer readable medium storing a program for causing a computer to perform a communication control method in a first radio station that serves a first cell, wherein
the communication control method comprises transmitting first constraint information on the first cell and second constraint information on a second cell served by a second radio station to a radio terminal that performs Dual Connectivity using the first cell and the second cell,
the first constraint information contains a first information element for specifying a first transmission constraint related to the first cell when the Dual Connectivity is performed,
the second constraint information contains a second information element for specifying a second transmission constraint related to the second cell when the Dual Connectivity is performed,
each of the first and second transmission constraints includes a period related to uplink signal transmission by the radio terminal, and
the communication control method further comprises transmitting information for instructing the radio terminal to start the period in the first cell.
28. A non-transitory computer readable medium storing a program for causing a computer to perform a communication control method in a second radio station that serves a second cell, wherein
the communication control method comprises:
transmitting second constraint information on the second cell to a radio terminal via a first radio station, the radio terminal being configured to perform Dual Connectivity using the second cell and a first cell served by the first radio station,
the second constraint information contains a second information element for specifying a second transmission constraint related to the second cell when the Dual Connectivity is performed, and is different from first constraint information on the first cell, transmitted from the first radio station to the radio terminal,
the first constraint information contains a first information element for specifying a first transmission constraint related to the first cell
each of the first and second transmission constraints includes a period related to uplink signal transmission by the radio terminal, and
the communication control method further comprises transmitting information for instructing the radio terminal to start the period in the second cell.
29. A non-transitory computer readable medium storing a program for causing a computer to perform a communication control method in a radio terminal, wherein
the communication control method comprises:
performing Dual Connectivity using a first cell served by a first radio station and a second cell served by a second radio station; and
receiving first constraint information and second constraint information from the first radio station,
the first constraint information contains a first information element for specifying a first transmission constraint related to the first cell when the Dual Connectivity is performed,
the second constraint information contains a second information element for specifying a second transmission constraint related to the second cell when the Dual Connectivity is performed,
each of the first and second transmission constraints includes a period related to uplink signal transmission by the radio terminal, and
the communication control method further comprises:
receiving information for instructing the radio terminal to start the period in the first cell from the first radio station; and
receiving information for instructing the radio terminal to start the period in the second cell from the second radio station.
30. The first radio station according to claim 9 , wherein the transceiver is configured to transmit information for instructing the radio terminal to start the period in the second cell.
31. The second radio station according to claim 13 , wherein the transceiver is configured to transmit information for instructing the radio terminal to start the period in the first cell.
32. The communication control method according to claim 19 , wherein the communication control method further comprises transmitting information for instructing the radio terminal to start the period in the second cell.
33. The communication control method according to claim 19 , wherein the second constraint information is sent from the second radio station to the first radio station.