Transmission of reference signals in a communication system

1. A user equipment (UE) comprising:

a transceiver configured to:

receive configuration information for a location of a channel state information (CSI) report trigger field in a downlink control information (DCI) format that includes multiple CSI report trigger fields; and

receive the DCI format; and

a controller configured to determine whether or not a value for the CSI report trigger field indicates a transmission of a CSI report,

wherein the transceiver is further configured to transmit a physical uplink control channel (PUCCH) that includes the CSI report when the value indicates a transmission of the CSI report.

2. The UE of claim 1 , wherein the transceiver is further configured to receive configuration information for a PUCCH resource field, a resource for the PUCCH transmission being determined based on a value of the PUCCH resource field and a number of values of CSI report trigger fields, with respective locations prior to the location, that indicate transmissions of respective CSI reports.

3. The UE of claim 1 , wherein:

the DCI format includes a PUCCH resource field; and

a resource for the PUCCH transmission is determined based on a value of the PUCCH resource field and a number of values of CSI report trigger fields, with respective locations prior to the location, that indicate transmissions of respective CSI reports.

4. The UE of claim 1 , wherein:

the DCI format includes a transmission power control (TPC) command field; and

a PUCCH transmission power is determined according to a value of the TPC command field.

5. The UE of claim 1 , wherein:

the DCI format indicates a reception of a channel state information reference signal (CSI-RS); and

the CSI report is determined based on the CSI-RS.

6. The UE of claim 1 , wherein:

the PUCCH transmission includes a transmission of a demodulation reference signal (DMRS); and

a DMRS structure is determined based on a coding rate of the CSI report.

7. The UE of claim 1 , wherein:

the PUCCH transmission is performed over a number of slots and includes a transmission of a demodulation reference signal (DMRS) over a number of sub-carriers; and

a ratio of the number of sub-carriers over the number of slots is smaller when the number of slots is larger than one than when the number of slots is one.

8. The UE of claim 1 , wherein the controller is configured to identify the CSI report trigger field in the DCI format for the UE from among the multiple CSI report trigger fields in the DCI format based on the location indicated in the received configuration information.

9. A base station comprising:

a transceiver configured to:

transmit configuration information for a location of a channel state information (CSI) report trigger field in a downlink control information (DCI) format that includes multiple CSI report trigger fields, and the DCI format; and

receive a physical uplink control channel (PUCCH) that includes a CSI report when a value for the CSI report trigger field indicates a transmission of the CSI report.

10. The base station of claim 9 , wherein the transceiver is further configured to transmit configuration information for a PUCCH resource field, a resource for the PUCCH reception being determined based on a value of the PUCCH resource field and a number of values of CSI report trigger fields, with respective locations prior to the location, that indicate receptions of respective CSI reports.

11. The base station of claim 9 , wherein the DCI format includes a transmission power control (TPC) command field.

12. The base station of claim 9 , wherein the DCI format indicates a transmission of a channel state information reference signal (CSI-RS).

13. The base station of claim 9 , wherein:

the PUCCH reception includes a reception of a demodulation reference signal (DMRS); and

a DMRS structure is determined based on a coding rate of the CSI report.

14. The base station of claim 9 , wherein:

the PUCCH reception includes a reception of a first demodulation reference signal (DMRS) and a second DMRS that is frequency division multiplexed with the first DMRS over a common bandwidth on a same reception symbol; and wherein the transceiver is further configured to demodulate, using the second DMRS, a signal received on same sub-carriers as the CSI report.

15. A method for a user equipment (UE) to transmit a CSI report, the method comprising:

receiving configuration information for a location of a channel state information (CSI) report trigger field in a downlink control information (DCI) format that includes multiple CSI report trigger fields;

receiving the DCI format;

determining whether or not a value for the CSI report trigger field indicates a transmission of a CSI report; and

transmitting a physical uplink control channel (PUCCH) that includes the CSI report when the value indicates a transmission of the CSI report.

16. The method of claim 15 , further comprising receiving configuration information for a PUCCH resource field, a resource for the PUCCH transmission being determined based on a value of the PUCCH resource field and a number of values of CSI report trigger fields, with respective locations prior to the location, that indicate transmissions of respective CSI reports.

17. The method of claim 15 , wherein:

the DCI format includes a PUCCH resource field; and

a resource for the PUCCH transmission is determined based on a value of the PUCCH resource field and a number of values of CSI report trigger fields, with respective locations prior to the location, that indicate transmissions of respective CSI reports.

18. The method of claim 15 , wherein:

the DCI format includes a transmission power control (TPC) command field; and

a PUCCH transmission power is determined according to a value of the TPC command field.

19. The method of claim 15 , wherein:

the DCI format indicates a reception of a channel state information reference signal (CSI-RS); and

the CSI report is determined based on the CSI-RS.

20. The method of claim 15 , wherein:

the PUCCH transmission includes a transmission of a demodulation reference signal (DMRS); and

a DMRS structure is determined based on a coding rate of the CSI report.

21. The method of claim 15 , wherein:

the PUCCH transmission is performed over a number of slots and includes a transmission of a demodulation reference signal (DMRS) over a number of sub-carriers; and

a ratio of the number of sub-carriers over the number of slots is smaller when the number of slots is larger than one than when the number of slots is one.