Methods and apparatus relating to LTE FDD-TDD inter-system carrier aggregation in advanced wireless communication systems

1. In a wireless communications system including a user equipment (UE) supporting frequency division duplex (FDD)-time division duplex (TDD) carrier aggregation (CA), a first access node operable to communicate with the UE on a first duplex mode carrier, and a second access node operable to communicate with the UE on a second duplex mode carrier, a method implemented in the first access node, the method comprising:

transmitting, to the UE, first radio resource control (RRC) signalling for data transmission through the first access node on the first duplex mode carrier as a primary component carrier (PCell);

transmitting, to the UE after transmitting the first RRC signalling, second RRC signalling on the PCell for data transmission through the second access node on the second duplex mode carrier as a secondary component carrier (SCell);

scheduling downlink data transmission on the PCell and the SCell via network backhaul; and

informing the UE of downlink data transmission on the PCell and the SCell using a first duplex mode downlink control information (DCI) format,

wherein, in processing the first duplex mode DCI format, the UE assumes that a DCI format of the same size received on the PCell provides downlink scheduling and uplink scheduling for the PCell and SCell.

2. The method as in claim 1 , wherein the second RRC signalling comprises dedicated RRC signalling.

3. The method as in claim 1 , wherein the first duplex mode is FDD and the second duplex mode is TDD.

4. The method as in claim 3 , wherein the first duplex mode is FDD and the second duplex mode is flexible TDD.

5. The method as in claim 1 , wherein the first duplex mode is TDD and the second duplex mode is FDD.

6. The method as in claim 1 , further comprising:

performing scheduling for data transmission on the SCell using cross-carrier scheduling.

7. The method as in claim 1 , further comprising:

performing scheduling for data transmission on an aggregated SCell using self-scheduling.

8. The method as in claim 7 , further comprising:

scheduling downlink data transmission only on the PCell,

wherein the second access node schedules downlink data transmission only on the SCell.

9. The method as in claim 8 , wherein the UE follows a first duplex mode timing and feedback rule for feeding back to the first access node a hybrid automatic repeat request acknowledgment (HARQ-ACK) in response to data received on the PCell, and follows a TDD timing and feedback rule for feeding back to the second access node a HARQ-ACK in response to data received on the SCell.

10. The method as in claim 9 , further comprising:

upon reception of the HARQ-ACK of the SCell on PUCCH, forwarding the received SCell HARQ-ACK to the second access node via backhaul.

11. The method as in claim 8 , further comprising:

informing the UE of downlink data transmission on the PCell using a first duplex mode downlink control information (DCI) format,

wherein the second access node informs the UE of downlink data transmission on the SCell using a second duplex mode DCI format.

12. The method as in claim 8 , further comprising:

scheduling uplink data transmission from the UE on the PCell; and

transmitting uplink grant for PCell transmission using a first duplex mode uplink scheduling timing rule.

13. The method as in claim 12 , wherein the second access node schedules uplink data transmission from the UE on the SCell, and transmits uplink grant for SCell transmission using a second duplex mode uplink scheduling timing rule.

14. The method as in claim 1 , wherein the UE follows a first duplex mode timing and feedback rule for feeding back to the first access node a hybrid automatic repeat request acknowledgment (HARQ-ACK) in response to data received on the PCell and the SCell.

15. The method as in claim 1 , further comprising:

scheduling uplink data transmission from the UE on the PCell and the SCell; and

transmitting uplink grant for PCell transmission and SCell transmission using a first duplex mode uplink scheduling timing rule.

16. The method as in claim 1 , wherein, upon reception of downlink scheduling for the SCell, the UE applies a first duplex mode timing rule for feeding back a HARQ-ACK to the PCell.

17. The method as in claim 16 , wherein, upon reception of uplink grant for uplink data transmission on the SCell carrier, the UE applies the first duplex mode timing rule for transmitting a physical uplink shared channel (PUSCH) to the SCell.

18. In a wireless communications system including a user equipment (UE) supporting frequency division duplex (FDD)-time division duplex (TDD) carrier aggregation (CA), a first access node operable to communicate with the UE on a first duplex mode carrier, and a second access node operable to communicate with the UE on a second duplex mode carrier, a method implemented in the UE, the method comprising:

receiving, from the first access node, first radio resource control (RRC) signalling for data transmission through the first access node on the first duplex mode carrier as a primary component carrier (PCell);

receiving, from the first access node after receiving the first RRC signalling, second RRC signalling on the PCell for data transmission through the second access node on the second duplex mode carrier as a secondary component carrier (SCell);

receiving, from the first access node, information of downlink data transmission on the PCell and the SCell using a first duplex mode downlink control information (DCI) format, after being scheduled, by the first access node, downlink data transmission on the PCell and the SCell via network backhaul; and

assuming, in processing the first duplex mode DCI format, that a DCI format of the same size received on the PCell provides downlink scheduling and uplink scheduling for the PCell and SCell.

19. A method implemented in a wireless communications system including a user equipment (UE) supporting frequency division duplex (FDD)-time division duplex (TDD) carrier aggregation (CA), a first access node operable to communicate with the UE on a first duplex mode carrier, and a second access node operable to communicate with the UE on a second duplex mode carrier, the method comprising:

transmitting, from the first access node to the UE, first radio resource control (RRC) signalling for data transmission through the first access node on the first duplex mode carrier as a primary component carrier (PCell); and

transmitting, from the first access node to the UE after transmitting the first RRC signalling, second RRC signalling on the PCell for data transmission through the second access node on the second duplex mode carrier as a secondary component carrier (SCell);

scheduling, by the first access node, downlink data transmission on the PCell and the SCell via network backhaul;

informing, by the first access node, the UE of downlink data transmission on the PCell and the SCell using a first duplex mode downlink control information (DCI) format; and

assuming, by the UE in processing the first duplex mode DCI format, that a DCI format of the same size received on the PCell provides downlink scheduling and uplink scheduling for the PCell and SCell.