Uplink switching of communication links for mobile stations in dual connectivity

1. A method, comprising:

receiving, by a mobile station, an uplink transmission pattern and a reception configuration indication, wherein

the reception configuration indication instructs the mobile station to support or not support simultaneous reception of data within the same subframe from a first base station via a first communication link and a second base station via a second communication link, and

the received uplink transmission pattern includes information on a predetermined number of subframes defining which subframes are usable by the mobile station for uplink transmissions via the first communication link to the first base station, which subframes are usable by the mobile station for uplink transmissions via the second communication link to the second base station, or which subframes are usable by the mobile station for switching uplink communication between the first and the second communication link; and

determining, by the mobile station, a downlink reception pattern based on the reception configuration indication, wherein

in response to the reception configuration indication instructing the mobile station to support the simultaneous reception of data, the downlink reception pattern defining a plurality of subframes that are usable by the mobile station for downlink reception via the first communication link from the first base station and via the second communication link from the second base station, and

in response to the reception configuration indication instructing the mobile station to not support the simultaneous reception of data, the downlink reception pattern defining, based on the uplink transmission pattern, which subframes are usable by the mobile station for downlink reception via the first communication link from the first base station, which subframes are usable by the mobile station for downlink reception via the second communication link from the second base station, and which subframes are usable by the mobile station for switching downlink communication between the first and the second communication link.

2. The method according to claim 1 , wherein the reception configuration indication includes either:

a one bit flag indicating to support or not support the simultaneous reception of data, or

an information element indicating a maximum multiplexing size, indicating a maximum number of acknowledgements/non-acknowledgements that can be multiplexed and transmitted in one subframe usable for uplink transmissions.

3. The method according to claim 1 , wherein the uplink transmission pattern includes information on a predetermined number of subframes defining which subframes are usable by the mobile station for uplink transmissions via the first communication link to the first base station, and which subframes are usable by the mobile station for uplink transmissions via the second communication link to the second base station, or

wherein the uplink transmission pattern includes information only on a predetermined number of subframes defining which subframes are usable by the mobile station for uplink transmissions via the first communication link to the first base station, the method further includes receiving, by the mobile station, another uplink transmission pattern, and the another uplink transmission pattern includes information on a predetermined number of subframes defining which subframes are usable by the mobile station for uplink transmission via the second communication link to the second base station, and which subframes are usable by the mobile station for switching between the first and second communication link.

4. The method according to claim 1 , wherein, in response to the reception configuration indication instructing the mobile station to not support the simultaneous reception of data, the determining of the downlink reception pattern includes:

determining a subframe n−4, that is four subframes before a subframe n which is usable for uplink transmissions via the first communication link to the first base station, to be usable for downlink reception via the first communication link from the first base station;

determining a subframe n−4, that is four subframes before a subframe n which is usable for uplink transmissions via the second communication link to the second base station, to be usable for downlink reception via the second communication link from the second base station; and

determining a subframe n−4, that is four subframes before a subframe n which is usable by the mobile node for switching uplink communication between the first and the second communication link, to be usable for switching downlink communication between the first and the second communication link.

5. The method according to claim 1 , wherein a downlink Hybrid Automatic Repeat Request (HARQ) protocol is used for downlink communication via the first and second communication links, and the method further includes:

bundling or multiplexing, by the mobile station, acknowledgements/non-acknowledgments for data, received by the mobile station in a plurality of consecutive subframes;

transmitting, by the mobile station, the acknowledgements/non-acknowledgments for data in a subframe usable for uplink transmissions that is four subframes after the last subframe of the plurality of consecutive subframes.

6. The method according to claim 5 , wherein the mobile station is configured with a maximum multiplexing size, the maximum multiplexing size indicating a maximum number of acknowledgements/non-acknowledgements that can be multiplexed and transmitted in one subframe usable for uplink transmissions.

7. The method according to claim 1 , wherein a Hybrid Automatic Repeat Request (HARQ) protocol with a plurality of HARQ processes is used for uplink communication via the first and second communication links, and the method further includes:

determining, by the mobile station, which HARQ processes out of the plurality of HARQ processes are used for uplink communication according to the uplink transmission pattern, such that a minimum round trip time of 8 ms is fulfilled for the HARQ protocol.

8. The method according to claim 1 , wherein the uplink transmission pattern is received by the first or second base station using a Media Access Control (MAC) protocol, Radio Resource Control (RRC) protocol, or physical layer signaling.

9. The method according to claim 1 , further comprising:

transmitting, by the mobile station, to a base station which is to transmit the reception configuration indication, information on a capability of the mobile station to support simultaneous reception of data within the same subframe from the first base station via the first communication link and the second base station via the second communication link.

10. The method according to claim 1 , further comprising:

preparing, by the mobile station, a first buffer status report based on uplink data to be transmitted via the first communication link;

preparing, by the mobile station, a second buffer status report based on uplink data to be transmitted via the second communication link;

transmitting, by the mobile station, the first buffer status report to the first base station;

transmitting, by the mobile station, the second buffer status report to the second base station; and

in a case where the first base station determines the uplink transmission pattern:

transmitting, by the mobile station, the second buffer status report to the first base station, or

transmitting, by the second base station, the second buffer status report to the first base station.

11. A mobile station, comprising:

a receiver, which, in operation, receives an uplink transmission pattern and a reception configuration indication, wherein

the reception configuration indication instructs the mobile station to support or not support simultaneous reception of data within the same subframe from a first base station via a first communication link and a second base station via a second communication link, and

the received uplink transmission pattern includes information on a predetermined number of subframes defining which subframes are usable by the mobile station for uplink transmissions via the first communication link to the first base station, which subframes are usable by the mobile station for uplink transmissions via the second communication link to the second base station, or which subframes are usable by the mobile station for switching uplink communication between the first and the second communication link; and

a processor, which, in operation, determines a downlink reception pattern based on the reception configuration indication, wherein

in response to the reception configuration indication instructing the mobile station to support the simultaneous reception of data, the downlink reception pattern defining a plurality of subframes that are usable by the mobile station for downlink reception via the first communication link from the first base station and via the second communication link from the second base station, and

in response to the reception configuration indication instructing the mobile station to not support the simultaneous reception of data, the downlink reception pattern defining, based on the uplink transmission pattern, defining, based on the uplink transmission pattern, which subframes are usable by the mobile station for downlink reception via the first communication link from the first base station, which subframes are usable by the mobile station for downlink reception via the second communication link from the second base station, and which subframes are usable by the mobile station for switching downlink communication between the first and the second communication link.

12. The mobile station according to claim 11 , wherein, in response to the reception configuration indication instructing the mobile station to not support the simultaneous reception of data, the processor, in operation:

determines a subframe n−4, that is four subframes before a subframe n which is usable for uplink transmissions via the first communication link to the first base station, to be usable for downlink reception via the first communication link from the first base station;

determines a subframe n−4, that is four subframes before a subframe n which is usable for uplink transmissions via the second communication link to the second base station, to be usable for downlink reception via the second communication link from the second base station; and

determines a subframe n−4, that is four subframes before a subframe n which is usable by the mobile node for switching uplink communication between the first and the second communication link, to be usable for switching downlink communication between the first and the second communication link.

13. The mobile station according to claim 11 , wherein a downlink Hybrid Automatic Repeat Request (HARQ) protocol is used for downlink communication via the first and second communication links,

wherein the processor, in operation, bundles or multiplexes acknowledgements/non-acknowledgments for data received by the mobile station in plurality of consecutive subframes

wherein the mobile station includes a transmitter, which, in operation, transmits the acknowledgements/non-acknowledgments for data in a subframe usable for uplink transmissions that is four subframes after the last subframe of the plurality of consecutive subframes.

14. The mobile station according to claim 13 wherein the mobile station is configured with a maximum multiplexing size, the maximum multiplexing size indicating a maximum number of acknowledgements/non-acknowledgements that can be multiplexed and transmitted in one subframe usable for uplink transmissions.

15. The mobile station according to claim 11 , wherein a Hybrid Automatic Repeat Request (HARQ) protocol with a plurality of HARQ processes is used for uplink communication via the first and second communication links, and

wherein the processor, in operation, determines which HARQ processes out of the plurality of HARQ processes are used for uplink communication according to the uplink transmission pattern, such that a minimum round trip time of 8 ms is fulfilled for the HARQ protocol.

16. The mobile station according to claim 11 , further comprising:

a transmitter, which, in operation, transmits to a base station which is to transmit the reception configuration indication, information on a capability of the mobile station to support simultaneous reception of data within the same subframe from the first base station via the first communication link and the second base station via the second communication link.

17. The mobile station according to claim 11 , wherein the processor, in operation:

prepares a first buffer status report based on uplink data to be transmitted via the first communication link; and

prepares a second buffer status report based on uplink data to be transmitted via the second communication link,

wherein the mobile station includes a transmitter, which, in operation:

transmits the first buffer status report to the first base station;

transmits the second buffer status report to the second base station; and

in a case where the first base station determines the uplink transmission pattern, transmits the second buffer status report to the first base station.