METHODS AND ARRANGEMENTS FOR CSI REPORTING

• US 20160050005A1
• Filed: 10/27/2015
• Published: 02/18/2016
• Est. Priority Date: 05/11/2012
• Status: Active Grant

• Current Assignee: Telefonaktiebolaget LM Ericsson
• Original Assignee: Telefonaktiebolaget LM Ericsson
• Inventors: HAMMARWALL, David, BERGMAN, Svante
• Granted Patent: US 9,641,236 B2
• Time in Patent Office: Days
• US Class Current: 1/1
• CPC Class Codes: H04B 7/0456 Selection of precoding matrices or codebooks, e.g. using matrices antenna weighting
• CPC Class Codes: H04B 7/0617 for beam forming
• CPC Class Codes: H04B 7/0619 using feedback from receiving side feedback signaling for adaptive modulation/coding H04L1/0001
• CPC Class Codes: H04B 7/0626 Channel coefficients, e.g. channel state information [CSI]
• CPC Class Codes: H04B 7/063 Parameters other than those covered in groups H04B7/0623 - H04B7/0634, e.g. channel matrix rank or transmit mode selection
• CPC Class Codes: H04B 7/0639 Using selective indices, e.g. of a codebook, e.g. pre-distortion matrix index [PMI] or for beam selection
• CPC Class Codes: H04L 1/0026 Transmission of channel quality indication
• CPC Class Codes: H04L 25/0224 using sounding signals
• CPC Class Codes: H04L 25/03949 equalizer selection or adaptation based on feedback multiple signaling inclusive of a precoding command for adapting the transmitter H04L1/0031; feedback for transmit diversity systems H04B7/0619; selection of codebook or precoding matrix for MIMO diversity systems H04B7/0456
• CPC Class Codes: H04L 5/0026 Division using four or more dimensions
• CPC Class Codes: H04L 5/0035 Resource allocation in a cooperative multipoint environment
• CPC Class Codes: H04L 5/005 of common pilots, i.e. pilots destined for multiple users or terminals
• CPC Class Codes: H04L 5/0057 Physical resource allocation for CQI
• CPC Class Codes: H04W 24/02 Arrangements for optimising operational condition
• CPC Class Codes: H04W 24/10 Scheduling measurement reports ; Arrangements for measurement reports
• CPC Class Codes: H04W 52/16 Deriving transmission power values from another channel
• CPC Class Codes: H04W 52/325 Power control of control or pilot channels

Abstract

Some embodiments provide a method in a wireless device for reporting channel state information, CSI, for a CSI process. The CSI process corresponds to a reference signal resource and an interference measurement resource. According to the method, the wireless device obtains an adjustment value associated with the CSI process. The wireless device estimates an effective channel based on one or more reference signals received in the reference signal resource, and applies the adjustment value to the estimated effective channel, thereby obtaining an adjusted effective channel. Furthermore, the wireless device determines channel state information based on the adjusted effective channel, and on interference estimated based on the interference measurement resource. Finally, the channel state information is transmitted to a network node.

Claims

1. A method in a wireless device for reporting channel state information, CSI, for a CSI process, the CSI process corresponding to a reference signal resource and an interference measurement resource, the method characterized in:

obtaining an adjustment value associated with the CSI process;

estimating an effective channel based on one or more reference signals received in the reference signal resource;

applying the adjustment value to the estimated effective channel, obtaining an adjusted effective channel;

determining channel state information based on the adjusted effective channel, and on interference estimated based on the interference measurement resource; and

transmitting the channel state information to a network node.

2. The method of claim 1, wherein the CSI process further corresponds to one or more interference emulation configurations, wherein each interference emulation configuration is associated with a reference signal received from an assumed interferer, the method further comprising:

estimating, for each interference emulation configuration, an effective channel based on the associated reference signal;

emulating interference for each interference emulation configuration based on the estimated effective channel for that configuration; and

determining channel state information based also on the emulated interference.

3. The method of claim 2, further comprising applying the adjustment value to the emulated interference for each interference emulation configuration.

4. The method of claim 2, further comprising obtaining a second adjustment value for the interference emulation configurations, and applying the second adjustment value to the emulated interference for each configuration.

5. The method of claim 1, wherein the CSI process corresponds to at least two reference signal resources, and wherein an adjustment value is associated with each one of the reference signal resources.

6. The method of claim 5, further comprising:

for each reference signal resource of the CSI process, estimating an effective channel based on one or more reference signals received in the reference signal resource, and applying the adjustment value associated with the reference signal resource to the estimated effective channel, obtaining an adjusted effective channel; and

determining channel state information based on the adjusted effective channels, and on estimated interference.

7. The method of claim 1, wherein the adjustment value is a power measurement offset.

8. The method of claim 7, wherein the method further comprises applying an additional non-CSI process-specific power offset to the estimated effective channel.

9. The method of claim 8, wherein the reference signal is a channel state information reference signal, CSI-RS, and wherein the additional power offset is associated with the CSI-RS.

10. The method of claim 1, wherein the adjustment value is a scaling factor.

11. The method of claim 1, further comprising determining channel state information for at least one other CSI process based on the adjustment value.

12. The method of claim 1, wherein the adjustment value is obtained from a network node.

13. The method of claim 1, further comprising receiving an index from a network node, and obtaining the adjustment value by retrieving the adjustment value corresponding to the index from a predefined lookup table.

14. The method of claim 1, wherein the channel state information comprises one or more of:

a channel quality indicator, a precoding matrix indicator, a rank indication, and a precoding matrix type.

15. The method of claim 1 wherein the wireless device is configured with two CSI processes corresponding to the same reference signal resource, and associated with different adjustment values.

16. The method of claim 1, wherein the reference signal resource comprises a set of resource elements in which one or more reference signals corresponding to a desired signal are received, and wherein the interference measurement resource comprises a set of resource elements in which one or more signals assumed to be interfering with the desired signal are received.

17. The method of claim 1, wherein the reference signal resource is a CSI-RS resource.

18. The method of claim 1, wherein the interference measurement resource is a cell-specific reference signal resource, and wherein interference is estimated by subtracting a decoded cell-specific reference signal from the signal received in the cell-specific reference signal resource.

19. A method in a network node for receiving, from a wireless device, channel state information, CSI, for a CSI process, the CSI process corresponding to a reference signal resource and an interference measurement resource, the network node being comprised in a cluster for coordinated multipoint transmission, the method characterized in:

transmitting, to the wireless device, an indication of an adjustment value associated with the CSI process;

receiving channel state information related to the CSI process from the wireless device.

20. The method of claim 19, wherein the reference signal resource comprises a set of resource elements in which one or more reference signals corresponding to a signal intended for reception by the wireless device are transmitted, and wherein the interference measurement resource comprises a set of resource elements in which one or more signals assumed to be interfering with the desired signal are received.