Wireless device, a network node and methods therein for reporting channel state information (csi) in a radio communications network

Abstract

A method performed by a wireless device ( 121, 122 ) for determining Channel State Information, CSI, estimates to be transmitted in a CSI report for the wireless device ( 121, 122 ) to a network node ( 110 ) in a radio communications network ( 100 ) is provided. The wireless device ( 121, 122 ) receives a message comprising an indication to use CSI estimates corresponding to a determined period of time. In response to said message, the wireless device ( 121, 122 ) determines CSI estimates to be used in the CSI report to the network node ( 110 ) according to the received indication. A wireless device ( 121, 122 ) is also described. A network node ( 110 ) and method therein for controlling CSI estimates transmitted by one or more wireless devices ( 121, 122 ) in CSI reports to the network node ( 110 ) in a radio communications network ( 100 ) are also provided.

1 . A method performed by a User Equipment, UE, for determining Channel State Information, CSI, estimates to be transmitted in a CSI report to a base station in a radio communications network, the method comprising:
 receiving a message comprising an indication to use CSI estimates that are based on CSI measurements performed during a determined period of time on resources configured for the UE;   determining CSI estimates to be used in the CSI report to the base station according to the received indication, wherein the CSI estimates are based on a CSI measurement at a single time instant on a CSI-RS resource configured for the UE; and   transmitting the CSI report to the base station, the CSI report including the determined CSI estimates.   
     
     
         2 . The method according to  claim 1 , wherein the CSI estimates are further based on a CSI measurement on a CSI-IM resource at a single time instant. 
     
     
         3 . The method according to  claim 1 , wherein the message is a Radio Resource Control, RRC, configuration message. 
     
     
         4 . The method according to  claim 1 , further comprising transmitting a confirmation of the determined period of time to the base station. 
     
     
         5 . A User Equipment, UE, for determining Channel State Information, CSI, estimates to be transmitted in a CSI report to a base station in a radio communications network, the wireless device comprising one or more processors whereby the wireless device is configured to:
 receive a message comprising an indication to use CSI estimates that are based on CSI measurements performed during a determined period of time on resources configured for the UE;   determine CSI estimates to be used in the CSI report to the base station according to the received indication, wherein the CSI estimates are based on a CSI measurement at a single time instant on a CSI-RS resource configured for the UE; and   transmit the CSI report to the base station, the CSI report including the determined CSI estimates.   
     
     
         6 . The UE according to  claim 5 , wherein the CSI estimates are further based on a CSI measurement on a CSI-IM resource at a single time instant. 
     
     
         7 . The UE according to  claim 5 , wherein the message is a Radio Resource Control, RRC, configuration message. 
     
     
         8 . The UE according to  claim 5 , further configured to transmit a confirmation of the determined period of time to the base station. 
     
     
         9 . A method performed by a base station for controlling Channel State Information, CSI, estimates transmitted by a User Equipment, UE, in CSI reports to the base station in a radio communications network, the method comprising:
 determining that the CSI estimates from the UE are no longer valid due to a change in at least one transmission condition;   transmitting, to the UE, a message comprising an indication to use CSI estimates that are based on CSI measurements performed during a determined period of time on resources configured for the UE; and   receiving a CSI report from the UE, the CSI report including CSI estimates in accordance with the indication to use CSI estimates that are based on CSI measurements performed during a determined period of time on resources configured for the UE, wherein the CSI estimates are based on a CSI measurement at a single time instant on a CSI-RS resource configured for the UE.   
     
     
         10 . The method according to  claim 9 , wherein the base station is configured for beamforming transmissions to the UE in the radio communications network, and wherein the change in the at least one transmission condition is a change in a transmitting beam used in beamforming transmissions to the UE. 
     
     
         11 . The method according to  claim 9 , wherein the change in the at least one transmission condition is a change in a traffic situation in a cell in which the UE is located, or a change in the determined period of time. 
     
     
         12 . The method according to  claim 9 , wherein the CSI estimates are further based on a CSI measurement on a CSI-IM resource at a single time instant. 
     
     
         13 . The method according to  claim 9 , wherein the message is a Radio Resource Control, RRC, configuration message. 
     
     
         14 . The method according to  claim 9 , wherein the message comprises an indication of the determined period of time. 
     
     
         15 . The method according to  claim 9 , further comprising:
 receiving a confirmation of the determined period of time from the UE.