Low complexity multi-configuration CSI reporting
Systems and methods for low complexity multi-configuration Channel State Information (CSI) reporting are provided. In some embodiments, a method of operating a wireless device in a cellular communications network to provide CSI feedback from multiple CSI reporting configurations is provided. The method includes receiving a first and second CSI reporting configuration and then reporting updated CSI in a CSI report for only one of the first CSI reporting configuration and the second CSI reporting configuration. In this way, rich CSI feedback with many ports, different codebooks, mixed beamformed and non-precoded CSI-RS configurations, etc., can be supported while requiring less computational complexity in the wireless device.
1. A method of operating a wireless device in a cellular communications network, to provide Channel State Information, CSI, feedback from multiple CSI reporting configurations, the method comprising:
receiving a first CSI reporting configuration;
receiving a second CSI reporting configuration;
reporting updated CSI in a CSI report for only one of the first CSI reporting configuration and the second CSI reporting configuration:
determining a first time instant corresponding to the first CSI reporting configuration;
determining a second time instant corresponding to the second CSI reporting configuration; and
calculating the CSI report using the second CSI reporting configuration if the first time instant is not between the second time instant and a third time instant, where the third time instant is later than the second time instant.
2. The method of claim 1 wherein:
determining the first time instant comprises determining the first time instant as one of the group comprising:
a time instant that contains a first CSI reference resource; and
a transmission time for a first CSI report.
3. The method of claim 1 wherein:
determining the second time instant comprises determining the second time instant as one of the group comprising:
a time instant that contains a second CSI reference resource; and
a transmission time for a second CSI report.
4. The method of claim 1 wherein the third time instant is one of the group comprising:
a time instant when the wireless device transmits the CSI report; and
a predetermined length after the second time instant, the predetermined length of time being at least one subframe.
5. The method of claim 4 wherein the predetermined length of time is (n cqi_ref −1) subframes such that the third time instant is (n cqi_ref −1) subframes after the second time instant.
6. The method of claim 1 wherein:
determining the first time instant comprises determining the first time instant as the time instant that contains the first CSI reference resource;
determining the second time instant comprises determining the second time instant as the time instant that contains the second CSI reference resource; and
the third time instant is the time instant when the wireless device transmits the CSI report.
7. The method of claim 1 wherein:
determining the first time instant comprises determining the first time instant as the transmission time for the first CSI report;
determining the second time instant comprises determining the second time instant as the transmission time for the second CSI report; and
the third time instant is the predetermined length after the second time instant, the predetermined length of time being at least one subframe.
8. The method of claim 1 wherein:
receiving the first CSI reporting configuration comprises receiving a first CSI resource for a CSI process of the wireless device; and
receiving the second CSI reporting configuration comprises receiving a second CSI resource for the CSI process of the wireless device.
9. The method of claim 8 further comprising:
receiving a CSI report request for either the first CSI reporting configuration or the second CSI reporting configuration; and
wherein reporting the CSI report for only one of the first CSI reporting configuration and the second CSI reporting configuration comprises reporting the CSI report for the one of the first CSI reporting configuration and the second CSI reporting configuration according to the CSI report request.
10. The method of claim 9 wherein receiving the CSI report request comprises:
receiving a value of “10” to indicate that the CSI report request is for the first CSI reporting configuration; and
receiving a value of “11” to indicate that the CSI report request is for the second CSI reporting configuration.
11. The method of claim 1 wherein a port associated with the first CSI reporting configuration and a port associated with the second CSI reporting configuration can always be assumed to be quasi-collocated.
12. The method of claim 1 wherein the wireless device does not expect to receive the first CSI reporting configuration and the second CSI reporting configuration that have different values of a higher layer parameter providing quasi-collocation information such as qcl-CRS-Info-r11.
13. A wireless device comprising:
at least one processor; and
memory comprising instructions executable by the at least one processor whereby the wireless device is operable to:
receive a first CSI reporting configuration;
receive a second CSI reporting configuration;
report an updated CSI report for only one of the first CSI reporting configuration and the second CSI reporting configuration;
determine a first time instant corresponding to the first CSI reporting configuration;
determine a second time instant corresponding to the second CSI reporting configuration; and
calculate the CSI report using the second CSI reporting configuration if the first time instant is not between the second time instant and a third time instant, where the third time instant is later than the second time instant.
14. The wireless device of claim 13 wherein:
determining the first time instant comprises being operable to determine the first time instant as one of the group comprising:
a time instant that contains a first CSI reference resource; and
a transmission time for a first CSI report.
15. The wireless device of claim 13 wherein:
determining the second time instant comprises being operable to determine the second time instant as one of the group comprising:
a time instant that contains a second CSI reference resource; and
a transmission time for a second CSI report.
16. The wireless device of claim 13 wherein the third time instant is one of the group comprising:
a time instant when the wireless device transmits the CSI report; and
a predetermined length after the second time instant, the predetermined length of time being at least one subframe.
17. The wireless device of claim 16 wherein the predetermined length of time is (n cqi_ref −1) subframes such that the third time instant is (n cqi_ref −1) subframes after the second time instant.
18. The wireless device of claim 13 wherein:
determining the first time instant comprises being operable to determine the first time instant as the time instant that contains the first CSI reference resource;
determining the second time instant comprises being operable to determine the second time instant as the time instant that contains the second CSI reference resource; and
the third time instant is the time instant when the wireless device transmits the CSI report.
19. The wireless device of claim 13 wherein:
determining the first time instant comprises being operable to determine the first time instant as the transmission time for the first CSI report;
determining the second time instant comprises being operable to determine the second time instant as the transmission time for the second CSI report; and
the third time instant is the predetermined length after the second time instant, the predetermined length of time being at least one subframe.
20. The wireless device of claim 13 wherein:
receiving the first CSI reporting configuration comprises being operable to receive a first CSI resource for a CSI process of the wireless device; and
receiving the second CSI reporting configuration comprises being operable to receive a second CSI resource for the CSI process of the wireless device.
21. The wireless device of claim 20 further operable to:
receive a CSI report request for either the first CSI reporting configuration or the second CSI reporting configuration; and
wherein reporting the CSI report for only one of the first CSI reporting configuration and the second CSI reporting configuration comprises being operable to report the CSI report for the one of the first CSI reporting configuration and the second CSI reporting configuration according to the CSI report request.
22. The wireless device of claim 21 wherein receiving the CSI report request comprises being operable to:
receive a value of “10” to indicate that the CSI report request is for the first CSI reporting configuration; and
receive a value of “11” to indicate that the CSI report request is for the second CSI reporting configuration.
23. The wireless device of claim 13 wherein a port associated with the first CSI reporting configuration and a port associated with the second CSI reporting configuration can always be assumed to be quasi-collocated.
24. The wireless device of claim 13 wherein the wireless device does not expect to receive the first CSI reporting configuration and the second CSI reporting configuration that have different values of a higher layer parameter providing quasi-collocation information such as qcl-CRS-Info-r11.
25. A wireless device adapted to:
receive a first CSI reporting configuration;
receive a second CSI reporting configuration;
report an updated CSI report for only one of the first CSI reporting configuration and the second CSI reporting configuration;
determine a first time instant corresponding to the first CSI reporting configuration;
determine a second time instant corresponding to the second CSI reporting configuration; and
calculate the CSI report using the second CSI reporting configuration if the first time instant is not between the second time instant and a third time instant, where the third time instant is later than the second time instant.