Method for reporting channel state information in wireless communication system and apparatus therefor
Provided are a method and an apparatus for reporting channel state information (CSI) by a user equipment in a wireless communication system. According to the present invention, the user equipment may receive configuration information related with the CSI from a base station and measure the CSI based on the configuration information. Thereafter, the user equipment includes reporting the CSI to the base station and the CSI includes a rank indicator (RI), a channel quality indicator (CQI), and an indicator indicating the number of amplitude coefficients other than 0 and the second part includes a precoding matrix indicator (PMI).
1. A method of reporting, by a user equipment (UE), channel state information (CSI) in a wireless communication system, the method comprising:
receiving, from a base station (BS), configuration information related with the CSI;
measuring the CSI based on the configuration information; and
reporting the CSI to the BS,
wherein the CSI comprises a first part and a second part,
wherein the first part includes a rank indicator (RI), a channel quality indicator (CQI), and an indicator indicating a number of amplitude coefficients other than 0,
wherein the second part includes a precoding matrix indicator (PMI),
wherein a number of bits of the indicator indicating the number of amplitude coefficients other than 0 is configured for each layer based on the following equation:
┌log 2 2 L− 1┐,
wherein L denotes a number of base vectors linearly combined by a linear combination based codebook.
2. The method of claim 1 , wherein a payload size of the second part is determined by the first part.
3. The method of claim 2 , wherein a bitwidth of the PMI is determined based on the rank indicator and the indicator of the number of amplitude coefficients other than 0.
4. The method of claim 1 , wherein the CSI is transmitted on a physical uplink shared channel (PUSCH), and
transmission power of the CSI increases as a number of bits of the first part increases.
5. The method of claim 1 , wherein the rank indicator, the channel quality indicator, and the indicator indicating the number of amplitude coefficients other than 0 are each divided into separate fields within the first part, and
wherein each of the separate fields is encoded with the same coding rate.
6. The method of claim 1 , wherein the indicator indicating the number of amplitude coefficients other than 0 is independently indicated for each layer.
7. The method of claim 1 , wherein L is a codebook configuration parameter indicated by higher layer signaling and is an integer.
8. The method of claim 1 ,
wherein the first part has a higher CSI priority than the second part, and
wherein the first part and the second part are mapped to a next symbol of a symbol to which a demodulation reference signal (DMRS) is mapped according to the CSI priority.
9. The method of claim 8 , wherein the first part and the second part are sequentially mapped in a direction in which an index of the symbol to which the DMRS is mapped increases.
10. The method of claim 1 , wherein a number of symbols to which the first part is mapped is determined based on a number of bits of the first part and a number of bits of the second part.
11. The method of claim 1 , wherein the first part and the second part are encoded according to different modulation orders and/or coding rates, respectively.
12. The method of claim 1 ,
wherein the first part and the second part are transmitted through different transmission powers, and
wherein specific values of the first part and/or the second part are/is repeatedly transmitted.
13. A user equipment (UE) configured to report channel state information (CSI) in a wireless communication system, the UE comprising:
at least one transceiver configured to transmit and receive a radio signal; and
at least one processor configured to control the at least one transceiver,
wherein the at least one processor is configured to:
receive, from a base station (BS), configuration information related with the CSI,
measure the CSI based on the configuration information, and
report the CSI to the BS,
wherein the CSI comprises a first part and a second part,
wherein the first part includes a rank indicator (RI), a channel quality indicator (CQI), and an indicator indicating a number of amplitude coefficients other than 0,
wherein the second part includes a precoding matrix indicator (PMI),
wherein a number of bits of the indicator indicating the number of amplitude coefficients other than 0 is configured for each layer based on the following equation:
┌log 2 2 L− 1┐,
wherein L is denotes a number of base vectors linearly combined by a linear combination based codebook.
14. The method of claim 1 ,
wherein the indicator indicating the number of amplitude coefficients other than 0 is encoded separately.