Method for transmitting/receiving channel state information in wireless communication system and device therefor
Disclosed are a method for transmitting/receiving channel state information (CSI) in a wireless communication system and a device therefor. Specifically, a method for transmitting channel state information by a terminal in a wireless communication system may comprise the steps of: determining CSI for a serving cell in an unlicensed band; and transmitting the CSI at a periodic CSI report time point within a reserved resource period (RRP) which is a time period reserved for transmitting/receiving data in the serving cell.
1. A method for transmitting, by a user equipment (UE), channel state information (CSI) in a wireless communication system, the method comprising:
determining CSI for a serving cell of an unlicensed band; and
transmitting the CSI at a periodic CSI reporting instance within a reserved resource period (RRP) which is a time period occupied to transmit and receive data in the serving cell,
wherein another CSI prior to an initial rank indication (RI) reporting instance within the RRP is dropped or transmitted through an out of range (OOR) message.
2. The method of claim 1 , wherein if a latest RI reported prior to the RRP is reported within a specific time window, the other CSI prior to the initial RI reporting instance within the RRP is determined based on the latest RI.
3. The method of claim 1 , wherein:
the CSI is transmitted on a physical uplink shared channel (PUSCH), and
the periodic CSI reporting instance is determined through a higher layer parameter.
4. The method of claim 1 , wherein:
the CSI comprises a wideband CSI value and a subband differential CSI value,
the subband differential CSI value indicates an offset level between the wideband CSI value and a subband CSI value, and
the offset level includes an out of range (OOR) state indicating that scheduling is inappropriate in the subband.
5. The method of claim 1 , wherein:
the CSI includes a representative CSI value of a subband group and a subband differential CSI value within each subband group,
the representative CSI value of the subband group is determined as an average value or median of CSI values of subbands belonging to the subband group or a CSI value of any one of subbands belonging to the subband group, and
the subband differential CSI value indicates an offset level between the representative CSI value of the subband group and a subband CSI value.
6. The method of claim 5 , wherein the offset level comprises an out of range (OOR) state indicating that scheduling is inappropriate in the subband group.
7. The method of claim 1 , wherein:
the CSI includes a wideband CSI value, a differential CSI value of a subband group, and a subband differential CSI value within each subband group,
the differential CSI value of the subband group indicates a first offset level between the wideband CSI value and a subband group CSI value,
the subband differential CSI value indicates a second offset level between the representative CSI value of the subband group and a subband CSI value, and
the representative CSI value of the subband group is determined as an average value or median of CSI values of subbands belonging to the subband group or a CSI value of any one of subbands belonging to the subband group.
8. The method of claim 7 , wherein the first offset level comprises an out of range (OOR) state indicating that scheduling is inappropriate in the subband group.
9. The method of claim 7 , wherein:
the differential CSI value of the subband group comprises a bitmap in which each subband group is mapped to each bit, and
whether scheduling in a corresponding subband group is appropriate is indicated based on a bit value of the bitmap.
10. The method of claim 1 , wherein in a frequency domain, each subband size is determined by control of an evolved NodeB (eNB) or selectively determined by the UE.
11. The method of claim 1 , wherein a unit of a component carrier which is an object of the CSI to be reported, a unit of a component carrier which is an object of radio resource management (RRM) measurement, and a unit of a component carrier which is a physical downlink shared channel (PDSCH) object are independently determined.
12. The method of claim 1 , wherein when determining the CSI by the UE, the UE assumes only interference measured in a specific resource element/symbol of resource elements/symbols forming a CSI-interference measurement (IM) resource.
13. The method of claim 1 , wherein the CSI includes one or more of a channel quality indicator (CQI), a precoding matrix indicator (PMI), a rank indication (RI), or a precoding type indicator (PTI).
14. A user equipment (UE) transmitting channel state information (CSI) in a wireless communication system, the UE comprising:
a radio frequency (RF) unit transmitting and receiving a radio signal; and
a processor controlling the UE,
wherein the processor:
determines CSI for a serving cell of an unlicensed band; and
transmits the CSI at a periodic CSI reporting instance within a reserved resource period (RRP) which is a time period occupied to transmit and receive data in the serving cell,
wherein another CSI prior to an initial rank indication (RI) reporting instance within the RRP is dropped or transmitted through an out of range (OOR) message.