Channel state information feedback design in advanced wireless communication systems

1. A method for providing feedback by a user equipment (UE) in a wireless communication system, the method comprising:

measuring signals received on a plurality of channel state information reference signal (CSI-RS) ports;

selecting a plurality of combinations of the CSI-RS ports;

applying a plurality of precoding matrixes to each of the selected combinations of CSI-RS ports;

calculating channel quality indicator (CQI) values for each of the applications of precoding matrixes to each of the selected combinations of CSI-RS ports;

selecting a selected port number (SPN), a selected port index (SPI), a precoding matrix indicator (PMI) corresponding to one of the plurality of precoding matrixes, and a rank indicator (RI) that yields a highest CQI from among the calculated CQI values, wherein the SPN is a number of selected CSI-RS ports and is equal to the RI, and wherein the SPI includes indices of the selected CSI-RS ports; and

sending feedback indicating the SPI, the highest CQI value, the PMI, and at least one of the SPN or the RI.

2. The method of claim 1 further comprising determining the SPN as the number of CSI-RS ports to select based on at least one of the calculated CQI values or a grouping of the CSI-RS ports.

3. The method of claim 1 , wherein selecting the SPN and the SPI comprises:

when the SPN and the SPI are calculated by the UE, selecting a number of CSI-RS ports whose signal power exceeds a threshold, selecting a number of CSI-RS ports whose total sum power exceed a threshold, or selecting a number of CSI-RS ports where each port is from a group of CSI-RS ports and received power exceed a threshold,

wherein the UE is configured to calculate the CQI values based on the selected SPN and the SPI, and

wherein the threshold is determined by the UE or configured by a base station.

4. The method of claim 1 , wherein:

the UE is configured to calculate the CQI values based on each of the plurality of the CSI-RS ports selection and select the CQI/PMI/SPN/SPI associated with a particular CQI, or calculate the CQI values and the PMI based on each of the plurality of possible combinations of CSI-RS ports whose received power exceeds the threshold and select the CQI/PMI/SPN/SPI associated with the highest CQI value, and

the threshold is determined by the UE or configured by a base station.

5. The method of claim 1 , wherein when the SPN is configured for the UE, selecting the number of the CSI-RS ports comprises selecting the number of the CSI-RS ports according to a value of the SPN configured for the UE.

6. The method of claim 1 , wherein when SPN/SPI sets are configured for the UE, selecting the number of the CSI-RS ports comprises selecting a SPN/SPI set from the configured SPN/SPI sets based on the calculated CQI values.

7. The method of claim 1 , wherein sending the feedback comprises sending the feedback including both the SPN and the SPI for each of the selected CSI-RS ports.

8. The method of claim 1 , wherein sending the feedback indicating at least the SPI for each of the selected CSI-RS ports comprises:

jointly encoding the SPN and the SPI using a selected port number and index (SPNI) index; and

sending the feedback including the SPNI index, wherein the SPN is fed back implicitly based on the SPN being equal to the RI.

9. An apparatus in a user equipment (UE) configured to provide feedback in a wireless communication system, the apparatus comprising:

a controller configured to measure signals received on a plurality of channel state information reference signal (CSI-RS) ports; select a plurality of combinations of the CSI-RS ports; apply a plurality of precoding matrixes to each of the selected combinations of CSI-RS ports; calculate channel quality indicator (CQI) values for each of the applications of precoding matrixes to each of the selected combinations of CSI-RS ports selection; and select a selected port number (SPN), a selected port index (SPI), a precoding matrix indicator (PMI) corresponding to one of the plurality of precoding matrixes, and a rank indicator (RI) that yields a highest CQI from among the calculated CQI values, wherein the SPN is a number of selected CSI-RS ports and is equal to the RI, and wherein the SPI includes indices of the selected CSI-RS ports; and

a transmitter configured to send feedback indicating the SPI, the CQI, the PMI and at least one of the SPN or the RI.

10. The apparatus of claim 9 , wherein the controller is configured to determine the SPN as the number of CSI-RS ports to select based on at least one of the calculated CQI values or a grouping of the CSI-RS ports.

11. The apparatus of claim 9 , wherein:

when the SPN and the SPI are calculated by the UE, the controller is configured to select a number of CSI-RS ports whose signal power exceeds a threshold, select a number of CSI-RS ports whose total sum power exceed a threshold, or select a number of CSI-RS ports where each port is from a group of CSI-RS ports and received power exceed a threshold,

the controller is configured to calculate the CQI values based on the selected SPN and the SPI, and

the threshold is determined by the UE or configured by a base station.

12. The apparatus of claim 9 , wherein:

the controller is configured to calculate the CQI values based on each of the plurality of the CSI-RS ports selection and select the CQI/PMI/USPN/SPI associated with a particular CQI, or calculate the CQI values based on each of the plurality of possible combinations of CSI-RS ports whose received power exceeds the threshold and select the CQI/PMI/SPN/SPI associated with the highest CQI value, and

the threshold is determined by the UE or configured by a base station.

13. The apparatus of claim 9 , wherein when the SPN is configured for the UE, the controller is configured to select the number of the CSI-RS ports according to a value of the SPN configured for the UE.

14. The apparatus of claim 9 , wherein when SPN/SPI sets are configured for the UE, the controller is configured to select a SPN/SPI set from the configured SPN/SPI sets based on the calculated CQI values.

15. The apparatus of claim 9 , wherein the transmitter is configured to send the feedback including the SPN and the SPI for each of the selected CSI-RS ports.

16. The apparatus of claim 9 , wherein:

the controller is configured to control joint encoding of the SPN and the SPI according to a selected port number and index (SPNI) index;

the transmitter is configured to send the feedback including the SPNI index; and

the SPN is fed back implicitly based on the SPN being equal to the RI.