Uneven Frequency-Domain Basis Allocation for Type II CSI Enhancements

Abstract

In certain embodiments, a method performed by a wireless device comprises estimating a channel state of a downlink channel and transmitting a CSI report for the downlink channel based on the channel state. The CSI report indicates a plurality of precoder vectors, each corresponding to a frequency sub-band of the bandwidth of the downlink channel, a precoder vector being expressed as a linear combination of spatial-domain components and frequency-domain component wherein each of the spatial-domain components is associated with a respective set of one or more frequency-domain components. The method further comprises determining, for each of the spatial-domain components, the number of associated frequency domain components in the set of one or more frequency-domain components associated with the spatial-domain component; determining linear combination coefficients for each combination of spatial-domain component and associated frequency-domain components; and including an indication of the determined linear combination coefficients as part of the CSI report.

1 . A method performed by a wireless device, the method comprising:
 estimating a channel state of a downlink channel; and   transmitting a channel state information (CSI) report for the downlink channel based on the channel state, the CSI report indicating a plurality of precoder vectors, wherein each of the precoder vectors corresponds to a frequency sub-band of the bandwidth of the downlink channel, a precoder vector being expressed as a linear combination of spatial-domain components and frequency-domain components, where each of the spatial-domain components is associated with a respective set of one or more frequency-domain components and where the number of frequency-domain components associated with a first spatial-domain component is larger than the number of frequency-domain components associated with a second spatial-domain component;   wherein the method further comprises:   determining, for each spatial-domain component of the spatial-domain components, which one or more frequency-domain components from a set of candidate frequency-domain components to be associated with that spatial-domain component;   determining a linear combination coefficients for each combination of spatial-domain component and an associated frequency-domain component; and   including an indication of the determined linear combination coefficients as part of the CSI report.   
     
     
         2 . The method of  claim 1 , wherein the number of linear combination coefficients included in the CSI report for the first spatial-domain component is larger than the number of linear combination coefficients included in the CSI report for the second spatial-domain component. 
     
     
         3 . The method of  claim 1 , wherein the CSI report further comprises an indication of the number of associated frequency-domain components for each spatial-domain component. 
     
     
         4 . The method of  claim 1 , wherein the CSI report further comprises an indication of the associated frequency-domain components for each of the spatial-domain components. 
     
     
         5 . (canceled) 
     
     
         6 . The method of  claim 3 , where the indication of the number of associated frequency-domain components for each of the spatial-domain components is jointly encoded with a selection of the one or more frequency-domain components associated with that spatial-domain component from the set of candidate frequency-domain components. 
     
     
         7 . A method performed by a base station, the method comprising:
 receiving a channel state information (CSI) report for a downlink channel, the CSI report indicating a plurality of precoder vectors, wherein each of the precoder vectors corresponds to a frequency sub-band of the bandwidth of the downlink channel, a precoder vector being expressed as a linear combination of spatial-domain components and frequency-domain components, where each of the spatial-domain components is associated with a respective set of one or more frequency-domain components and where the number of frequency-domain components associated with a first spatial-domain component is larger than the number of frequency-domain components associated with a second spatial-domain component, wherein the received CSI report includes an indication of linear combination coefficients for each combination of spatial-domain component and associated frequency-domain components;   determining precoding to use for transmitting data to a wireless device based at least in part on the CSI report; and   transmitting data to the wireless device according to the precoding.   
     
     
         8 . The method of  claim 7 , wherein the number of linear combination coefficients received in the CSI report for the first spatial-domain component is larger than the number of linear combination coefficients received in the CSI report for the second spatial-domain component. 
     
     
         9 . The method of  claim 7 , wherein the CSI report further comprises an indication of the number of associated frequency-domain components for each spatial-domain component. 
     
     
         10 . The method of  claim 7 , wherein the CSI report further comprises an indication of the associated frequency-domain components for each of the spatial-domain components. 
     
     
         11 . (canceled) 
     
     
         12 . The method of  claim 9 , where the indication of the number of associated frequency-domain components for each of the spatial-domain components is jointly encoded with a selection of the one or more frequency-domain components associated with that spatial-domain component from a set of candidate frequency-domain components. 
     
     
         13 . A wireless device comprising:
 power supply circuitry configured to supply power to the wireless device; and   processing circuitry configured to:   estimate a channel state of a downlink channel; and   transmit a channel state information (CSI) report for the downlink channel based on the channel state, the CSI report indicating a plurality of precoder vectors, wherein each of the precoder vectors corresponds to a frequency sub-band of the bandwidth of the downlink channel, a precoder vector being expressed as a linear combination of spatial-domain components and frequency-domain components, where each of the spatial-domain components is associated with a respective set of one or more frequency-domain components and where the number of frequency-domain components associated with a first spatial-domain component is larger than the number of frequency-domain components associated with a second spatial-domain component;   wherein the processing circuitry is further configured to:   determine, for each of the spatial-domain components, which one or more frequency-domain components from a set of candidate frequency-domain components to be associated with that spatial-domain component;   determine a linear combination coefficient for each combination of a spatial-domain component and an associated frequency-domain component; and   include an indication of the determined linear combination coefficients as part of the CSI report.   
     
     
         14 . The wireless device of  claim 13 , wherein the number of linear combination coefficients included in the CSI report for the first spatial-domain component is larger than the number of linear combination coefficients included in the CSI report for the second spatial-domain component. 
     
     
         15 . The wireless device of  claim 13 , wherein the CSI report further comprises an indication of the number of associated frequency-domain components for each spatial-domain component. 
     
     
         16 . The wireless device of  claim 13 , wherein the CSI report further comprises an indication of the associated frequency-domain components for each of the spatial-domain components. 
     
     
         17 . (canceled) 
     
     
         18 . The wireless device of  claim 15 , where the indication of the number of associated frequency-domain components for each of the spatial-domain components is jointly encoded with a selection of the one or more frequency-domain components associated with that spatial-domain component from the set of candidate frequency-domain components. 
     
     
         19 . A base station comprising:
 power supply circuitry configured to supply power to the base station; and   processing circuitry configured to:   receive a channel state information (CSI) report for a downlink channel, the CSI report indicating a plurality of precoder vectors, wherein each of the precoder vectors corresponds to a frequency sub-band of the bandwidth of the downlink channel, a precoder vector being expressed as a linear combination of spatial-domain components and frequency-domain components, where each of the spatial-domain components is associated with a respective set of one or more frequency-domain components and where the number of frequency-domain components associated with a first spatial-domain component is larger than the number of frequency-domain components associated with a second spatial-domain component, wherein the received CSI report includes an indication of linear combination coefficients for each combination of spatial-domain component and associated frequency-domain components;   determine precoding to use for transmitting data to a wireless device based at least in part on the CSI report; and   transmit data to the wireless device according to the precoding.   
     
     
         20 . The base station of  claim 19 , wherein the number of linear combination coefficients received in the CSI report for the first spatial-domain component is larger than the number of linear combination coefficients received in the CSI report for the second spatial-domain component. 
     
     
         21 . The base station of  claim 19 , wherein the CSI report further comprises an indication of the number of associated frequency-domain components for each spatial-domain component. 
     
     
         22 . The base station of  claim 19 , wherein the CSI report further comprises an indication of the associated frequency-domain components for each of the spatial-domain components. 
     
     
         23 . (canceled) 
     
     
         24 . The base station of  claim 21 , where the indication of the number of associated frequency-domain components for each of the spatial-domain components is jointly encoded with a selection of the one or more frequency-domain components associated with that spatial-domain component from the set of candidate frequency-domain components.