Periodic channel state information reporting for time division duplex (TDD) carrier aggregation systems
Technology for periodic channel state information (CSI) reporting is disclosed. One method can include a user equipment (UE) identifying a configured CSI reporting instance for a secondary cell to report the periodic CSI to a node based on a CSI reporting configuration of the secondary cell. The UE can determine that the configured CSI reporting instance of the secondary cell used to report the periodic CSI does not correspond with an uplink (UL) subframe of a primary cell. The UE can transmit the periodic CSI report for the secondary cell, to the node, using a physical uplink shared channel (PUSCH) on the secondary cell when the periodic CSI reporting instance for the secondary cell does not correspond with the UL subframe of the primary cell and an UL-SCH (Uplink Shared Channel) is available in a subframe that corresponds to the periodic CSI reporting instance of the secondary cell.
1. A user equipment (UE), the UE comprising circuitry configured to:
identify a reporting period and an offset period for a secondary cell to report a periodic channel state information (CSI) report for the secondary cell to an evolved node B (eNB) based on a CSI reporting configuration of the secondary cell;
identify if an uplink (UL) subframe of a primary cell used to send a periodic CSI report using a Physical Uplink Control Channel (PUCCH) on the primary cell corresponds to a subframe of a periodic CSI reporting instance of the secondary cell;
identify if the UL subframe of the primary cell does not correspond to the subframe of the periodic CSI reporting instance of the secondary cell, the periodic CSI reporting instance being determined based on the reporting period and the offset period for the secondary cell;
transmit the periodic CSI report for the secondary cell, to the eNB, using the PUCCH on the primary cell when the UL subframe of the primary cell corresponds to the subframe of the periodic CSI reporting instance of the secondary cell; and
drop the periodic CSI report for the secondary cell when the subframe of the periodic CSI reporting instance for the secondary cell does not correspond with the UL subframe of the primary cell.
2. The UE of claim 1 , wherein the circuitry is further configured to transmit the periodic CSI report for the secondary cell using the PUCCH on the primary cell, wherein a reporting period of N pd =1 for a serving cell applies to Time-Division Duplex (TDD) uplink-downlink (UL-DL) configurations 0, 1, 3, 4, or 6 for the primary cell and all UL subframes of the primary cell are used for periodic CSI reporting, the N pd value of 5 applies to TDD UL-DL configurations 0, 1, 2, or 6 for the primary cell, and the N pd value of 10, 20, 40, 80, or 160 applies to TDD UL-DL configurations 0, 1, 2, 3, 4, 5, or 6 for the primary cell.
3. The UE of claim 1 , wherein the primary cell has a Time-Division Duplex (TDD) uplink-downlink (UL-DL) configuration different than a TDD UL-DL configuration of the secondary cell.
4. The UE of claim 1 , wherein the periodic CSI report for the secondary cell is transmitted on one of a PUCCH format 2 or 2a or 2b or 3 of the primary cell when the UL subframe of the primary cell corresponds with the subframe of the periodic CSI reporting instance for the secondary cell.
5. The UE of claim 1 , wherein the circuitry is further configured to multiplex the periodic CSI report for the secondary cell on a Physical Uplink Shared Channel (PUSCH) of the secondary cell when the UL subframe is unavailable on the primary cell and an UL-SCH (Uplink Shared Channel) on the secondary cell is available in an UL subframe of the secondary cell.
6. The UE of claim 1 , wherein the circuitry is further configured to receive the CSI reporting configuration of the secondary cell from the eNB, based on a Channel Quality Index-Precoding Matrix Indicator (CQI-PMI) configuration index that determines both a reporting period (N pd ) and an offset period for the periodic CSI reporting instance for UL subframes of the secondary cell.
7. The UE of claim 1 , wherein the circuitry is further configured to override the CSI reporting configuration of the secondary cell with a CSI reporting configuration of the primary cell when the subframe of the periodic CSI reporting instance for the secondary cell does not correspond with the UL subframe on the primary cell.