Interference measurements and channel state information feedback for multi-user multiple-in multiple-out
Methods and apparatuses for channel state information (CSI) feedback in a wireless network. In one embodiment, a method includes receiving signaling including a first Non-Zero Power (NZP) CSI-reference signal (RS) configuration for channel measurement; a second NZP CSI-RS configuration; and a CSI interference measurement (CSI-IM) configuration for interference measurement. The method includes receiving a CSI feedback request and estimating the CSI based on at least the signaled first NZP CSI-RS configuration, the second NZP CSI-RS configuration, and the CSI-IM configuration.
1. A method for a user equipment, UE, the method comprising:
receiving signaling, by the UE, the signaling including:
a first Non-Zero Power, NZP, channel state information, CSI,-reference signal, RS, configuration for channel measurement;
a second NZP CSI-RS configuration for interference measurement;
a CSI interference measurement, CSI-IM, configuration for interference measurement; and
a codebook configuration;
receiving a CSI feedback request associated with the signaled first NZP CSI-RS configuration, the second NZP CSI-RS configuration, and the CSI-IM configuration;
measuring a downlink channel on a single first NZP CSI-RS resource corresponding to the first NZP CSI-RS configuration; and
transmitting a CSI report based on the signaled first NZP CSI-RS configuration, the second NZP CSI-RS configuration and the CSI-IM configuration.
2. The method according to claim 1 , wherein the second NZP CSI-RS configuration is for K NZP CSI-RS resources for the interference measurement, where K>=1.
3. The method according to claim 2 , further comprising measuring interference on each of the K NZP CSI-RS resources corresponding to the second NZP CSI-RS configuration.
4. The method according to claim 3 , wherein the measuring the interference on each of the K NZP CSI-RS resources results in K interference power estimates.
5. The method according to claim 1 , further comprising measuring interference on at least one CSI-IM resource corresponding to the CSI-IM configuration.
6. The method according to claim 4 , further comprising accounting for at least the K interference power estimates based on the K NZP CSI-RS resources and at least one interference measurement based on at least one CSI-IM resource to obtain a combined interference estimate.
7. The method according to claim 6 , wherein an estimated CSI is based on the combined interference estimate and the measured downlink channel.
8. A user equipment, UE, comprising processing circuitry configured to cause the UE to:
receive signaling, the signaling including:
a first Non-Zero Power, NZP, channel state information, CSI,-reference signal, RS, configuration for channel measurement;
a second NZP CSI-RS configuration for interference measurement;
a CSI interference measurement, CSI-IM, configuration for interference measurement; and
a codebook configuration;
receive a CSI feedback request associated with the signaled first NZP CSI-RS configuration, the second NZP CSI-RS configuration, and the CSI-IM configuration;
measure a downlink channel on a single first NZP CSI-RS resource corresponding to the first NZP CSI-RS configuration; and
transmit a CSI report based on the signaled first NZP CSI-RS configuration, the second NZP CSI-RS configuration and the CSI-IM configuration.
9. The UE according to claim 8 , wherein the second NZP CSI-RS configuration is for K NZP CSI-RS resources for the interference measurement, where K>=1.
10. The UE according to claim 8 , wherein the processing circuitry is configured to cause the UE to measure interference on each of the K NZP CSI-RS resources corresponding to the second NZP CSI-RS configuration.
11. The UE according to claim 10 , wherein the processing circuitry is configured to measure the interference on each of the K NZP CSI-RS resources resulting in K interference power estimates.
12. The UE according to claim 8 , wherein the processing circuitry is configured to cause the UE to measure interference on at least one CSI-IM resource corresponding to the CSI-IM configuration.
13. The UE according to claim 11 , wherein the processing circuitry is configured to cause the UE to account for at least the K interference power estimates based on the K NZP CSI-RS resources and at least one interference measurement based on at least one CSI-IM resource to obtain a combined interference estimate.
14. The UE according to claim 13 , wherein the processing circuitry is configured to cause the UE to estimate CSI based on the combined interference estimate and the measured downlink channel.
15. A base station comprising processing circuitry, the processing circuitry configured to cause the base station to:
signal to a user equipment, UE:
a first Non-Zero Power, NZP, channel state information, CSI,-reference signal, RS, configuration for channel measurement;
a second NZP CSI-RS configuration for interference measurement;
a CSI interference measurement, CSI-IM, configuration for interference measurement; and
a codebook configuration;
send a CSI feedback request associated with the signaled first NZP CSI-RS configuration, the second NZP CSI-RS configuration, and the CSI-IM configuration;
receive a CSI report from the UE, the CSI report being based at least in part on:
a downlink channel measurement on a single first NZP CSI-RS resource corresponding to the signaled first NZP CSI-RS configuration;
the second NZP CSI-RS configuration; and
the CSI-IM configuration.
16. The base station according to claim 15 , wherein the second NZP CSI-RS configuration is for K NZP CSI-RS resources for the interference measurement, where K>=1.
17. The base station according to claim 16 , wherein the processing circuitry is further configured to transmit K+1 NZP CSI-reference signals, RSs, over K+1 NZP CSI-RS resources configured by the signaling of the first NZP CSI-RS configuration and the second NZP CSI-RS configuration.
18. The base station according to claim 16 , wherein the received CSI report is based on a combined interference estimate and the measured downlink channel, the combined interference estimate accounting for at least K interference power estimates based on the K NZP CSI-RS resources configured by the second NZP CSI-RS configuration and at least one interference measurement based on at least one CSI-IM resource configured by the CSI-IM configuration.
19. The method according to claim 2 , wherein K+1 corresponds to a number of UE candidates for Multi-user Multiple-input Multiple-output, MU-MIMO, all UE candidates being within a single cell.
20. The UE according to claim 9 , wherein K+1 corresponds to a number of UE candidates for Multi-user Multiple-input Multiple-output, MU-MIMO, all UE candidates being within a single cell.
21. The base station according to claim 16 , wherein K+1 corresponds to a number of UE candidates for Multi-user Multiple-input Multiple-output, MU-MIMO, all UE candidates being within a single cell.