Periodic channel state information reporting for time division duplex (TDD) carrier aggregation systems

1. An apparatus of a user equipment (UE) operable to report periodic channel state information (CSI) to an eNodeB, the apparatus comprising:

memory; and

one or more processors configured to:

determine, at the UE, a reporting period (N pd ) of a serving cell of the UE of a plurality of serving cells of the UE, each of the plurality of serving cells having a serving cell index;

determine, at the UE, a Time-Division Duplex (TDD) uplink-downlink (UL-DL) configuration of a primary cell of the UE; and

encode, at the UE, multiple periodic CSI reports for transmission to the eNodeB in a wireless network using a physical uplink control channel (PUCCH) on the primary cell according to the reporting period N pd ,

wherein each of the multiple periodic CSI reports corresponds to one or more CSI processes and each CSI process has a CSI process index, and

wherein when carrier aggregation and coordinated multipoint (CoMP) transmission mode 10 are used in the wireless network, colliding periodic CSI reports for the plurality of serving cells in the multiple periodic CSI reports having a PUCCH reporting type of a same priority and a same CSI process index are dropped at the UE, except a colliding periodic CSI report corresponding to a one of the plurality of serving cells with a lowest serving cell index;

wherein:

the reporting period N pd =1 is selected for the serving cell when the TDD UL-DL configuration of the primary cell is 0, 1, 3, 4, or 6 and all UL subframes of the primary cell in a radio frame are used for periodic CSI reporting; or

the reporting period N pd =5 is selected for the serving cell when the TDD UL-DL configuration of the primary cell is 0, 1, 2, or 6; or

the reporting period N pd =10, 20, 40, 80, or 160 is selected for the serving cell for all TDD UL-DL configurations of the primary cell.

2. The apparatus of claim 1 , further comprising a transceiver configured to transmit the multiple periodic CSI reports to the eNodeB.

3. The apparatus of claim 1 , wherein colliding periodic CSI reports of the serving cell are dropped at the UE except a periodic CSI report corresponding to a CSI process with a lowest CSI process index.

4. The apparatus of claim 1 , wherein the one or more processors are configured to encode the multiple periodic CSI reports for transmission to the eNodeB using the transmission mode (TM) 10 .

5. The apparatus of claim 1 , wherein the multiple periodic CSI reports include periodic channel quality indicator-precoding matrix indicator (CQI-PMI) reports.

6. The apparatus of claim 1 , wherein the multiple periodic CSI reports include one or more of: a channel quality indicator (CQI), a precoding matrix indicator (PMI), a precoding type indicator (PTI) or a rank indicator (RI).

7. The apparatus of claim 1 , wherein the reporting period N pd is determined based on a channel quality indicator-precoding matrix indicator (CQI-PMI) configuration index (cqi-pmi-ConfigIndex) parameter received from the eNodeB via radio resource control (RRC) signaling.

8. The apparatus of claim 1 , wherein the reporting period N pd is defined as a number of subframes after which the UE is configured to transmit the multiple periodic CSI reports to the eNodeB.

9. At least one non-transitory computer readable medium having instructions embodied thereon for reporting periodic channel state information (CSI) from a user equipment (UE) to an eNodeB, the instructions when executed using one or more processors perform the following:

determining, at the UE, a reporting period (N pd ) of a serving cell of the UE of a plurality of serving cells of the UE, each of the plurality of serving cells having a serving cell index;

determining, at the UE, a Time-Division Duplex (TDD) uplink-downlink (UL-DL) configuration of a primary cell of the UE;

encoding, at the UE, multiple periodic CSI reports for transmission to the eNodeB in a wireless network using a physical uplink control channel (PUCCH) on the primary cell according to the reporting period N pd , wherein each of the periodic CSI reports corresponds to one or more CSI processes and each CSI process has a CSI process index; and

when carrier aggregation and coordinated multipoint (CoMP) transmission mode 10 are used in the wireless network, dropping, at the UE, colliding periodic CSI reports for the plurality of serving cells in the multiple CSI reports having a PUCCH reporting type of a same priority and a same CSI process index except a colliding periodic CSI report corresponding to a one of the plurality of serving cells with a lowest serving cell index;

wherein:

the reporting period N pd =1 is selected for the serving cell when the TDD UL-DL configuration of the primary cell is 0, 1, 3, 4, or 6 and all UL subframes of the primary cell in a radio frame are used for periodic CSI reporting; or

the reporting period N pd =5 is selected for the serving cell when the TDD UL-DL configuration of the primary cell is 0, 1, 2, or 6; or

the reporting period N pd =10, 20, 40, 80, or 160 is selected for the serving cell for all TDD UL-DL configurations of the primary cell.

10. The at least one non-transitory computer readable medium of claim 9 , wherein colliding periodic CSI reports of the serving cell are dropped at the UE except a periodic CSI report corresponding to a CSI process with a lowest CSI process index.

11. The at least one non-transitory computer readable medium of claim 9 , further comprising instructions which when executed perform the following: encoding the multiple periodic CSI reports for transmission to the eNodeB using the transmission mode (TM) 10 .

12. The at least one non-transitory computer readable medium of claim 9 , wherein the multiple periodic CSI reports include periodic channel quality indicator-precoding matrix indicator (CQI-PMI) reports.

13. The at least one non-transitory computer readable medium of claim 9 , wherein the multiple periodic CSI reports include one or more of: a channel quality indicator (CQI), a precoding matrix indicator (PMI), a precoding type indicator (PTI) or a rank indicator (RI).

14. The at least one non-transitory computer readable medium of claim 9 , wherein the reporting period N pd is determined based on a channel quality indicator-precoding matrix indicator (CQI-PMI) configuration index (cqi-pmi-ConfigIndex) parameter received from the eNodeB via radio resource control (RRC) signaling.

15. The at least one non-transitory computer readable medium of claim 9 , wherein the reporting period Npd is defined as a number of subframes after which the UE is configured to transmit the multiple periodic CSI reports to the eNodeB.