Methods and arrangements for CSI reporting

1. A method, in a wireless device, for reporting Channel State Information (CSI), the wireless device being comprised in a wireless communications system, the method comprising:

receiving a CSI process configuration and a request for CSI from a network node, wherein a CSI process is a process by which CSI is reported for a reference signal resource and an interference measurement resource;

determining, based on a number of CSI processes with which the wireless device is configured, a location of a CSI reference resource relative to a subframe in which a CSI report is to be transmitted responsive to the request, wherein a number N represents the determined location, and N increases when the number of configured CSI processes exceeds a certain threshold or N increases with the number of configured CSI processes; and

reporting CSI for one or more CSI processes by transmitting the CSI report, wherein the CSI reflects a state of a channel for the CSI reference resource.

2. The method of claim 1 , wherein N is applied to all CSI processes configured for the wireless device.

3. The method of claim 1 , wherein the determining the location of the CSI reference resource comprises determining the location of the CSI reference resource further based on a number of configured CSI-RS resources.

4. The method of claim 1 , further comprising:

prioritizing a first CSI process over a second CSI process;

determining a rank indicator and/or a precoding matrix indicator for the first CSI process;

reusing the determined rank indicator and/or precoding matrix indicator for the second CSI process.

5. The method of claim 1 , further comprising:

performing measurements on reference signal resources corresponding to the configured CSI processes;

determining the CSI based on the measurements.

6. The method of claim 1 , wherein the CSI is determined based on measurements performed in and/or prior to the CSI reference resource.

7. The method of claim 1 , wherein the request for CSI is a request for a periodic CSI report, or a request for an aperiodic CSI report.

8. The method of claim 1 , further comprising:

performing measurements on interference measurement resources corresponding to the configured CSI processes;

determining the CSI based on the measurements.

9. A wireless device for reporting Channel State Information (CSI), the wireless device comprising:

memory comprising instructions;

processing circuitry operatively connected to the memory and configured, when executing the instructions, to cause the wireless device to:

receive, from a network node, a CSI process configuration and a request for CSI, wherein a CSI process is a process by which CSI is reported for a reference signal resource and an interference measurement resource;

determine, based on a number of CSI processes with which the wireless device is configured, a location of a CSI reference resource relative to a subframe in which a CSI report is to be transmitted responsive to the request, wherein a number N represents the determined location, and N increases when the number of configured CSI processes exceeds a certain threshold or N increases with the number of configured CSI processes; and

report CSI for one or more CSI processes by transmitting the CSI report, wherein the CSI reflects a state of a channel for the CSI reference resource.

10. The wireless device of claim 9 , wherein the wireless device is a user equipment.

11. The wireless device of claim 9 , wherein the processing circuitry, when executing the instructions, is further configured to determine the location of the CSI reference resource further based on a number of configured CSI-RS resources.

12. The wireless device of claim 9 , wherein the processing circuitry, when executing the instructions, is further configured to:

prioritize a first CSI process over a second CSI process;

determine a rank indicator and/or a precoding matrix indicator for the first CSI process;

reuse the determined rank indicator and/or precoding matrix indicator for the second CSI process.

13. The wireless device of claim 9 , wherein the processing circuitry, when executing the instructions, is further configured to:

perform measurements on reference signal resources corresponding to the configured CSI processes;

determine the CSI based on the measurements.

14. The wireless device of claim 9 , wherein the processing circuitry, when executing the instructions, is further configured to determine the CSI based on measurements performed in and/or prior to the CSI reference resource.

15. The wireless device of claim 9 , wherein the processing circuitry, when executing the instructions, is further configured to:

perform measurements on interference measurement resources corresponding to the configured CSI processes;

determine the CSI based on the measurements.

16. The method of claim 1 , wherein the location is determined to be greater than 4 subframes prior to the subframe in which the CSI report is to be transmitted responsive to the request.

17. The wireless device of claim 9 , wherein the location is determined to be greater than 4 subframes prior to the subframe in which the CSI report is to be transmitted responsive to the request.