Method and apparatus for transmitting aperiodic channel state information in wireless communication system
A method is provided for receiving aperiodic channel state information (CSI). A base station (BS) transmits, to a user equipment (UE), an uplink downlink control information (DCI) format. The BS receives, from the UE, aperiodic CSI through a physical uplink shared channel (PUSCH) if the BS triggers an aperiodic CSI report using a CSI request field included in the uplink DCI format. The CSI request field is either a 1-bit field or a multi-bit field. When the UE is configured with only one cell, the 1-bit field is included in the uplink DCI. When the UE is configured with more than one channel state information-reference signal (CSI-RS), the multi-bit field is included in the uplink DCI.
1. A method for receiving aperiodic channel state information (CSI), the method performed by a base station (BS) and comprising:
transmitting, to a user equipment (UE), an uplink downlink control information (DCI) format; and
receiving, from the UE, aperiodic CSI through a physical uplink shared channel (PUSCH) if the BS triggers an aperiodic CSI report using a CSI request field included in the uplink DCI format,
wherein the CSI request field is either a 1-bit field or a multi-bit field,
wherein, when the UE is configured with only one cell, the CSI request field included in the uplink DCI format is the 1-bit field,
wherein, when the UE is configured with more than one channel state information-reference signal (CSI-RS), the CSI request field included in the uplink DCI format is the multi-bit field,
wherein, when the CSI request field is the multi-bit field, the CSI request field has a value among a plurality of candidate values,
wherein the plurality of candidate values comprises a first value which triggers an aperiodic CSI report for a first set of reference signals and a second value which triggers an aperiodic CSI report for a second set of reference signals, and
wherein the first set of reference signals and the second set of reference signals are configured by a higher layer signal.
2. The method of claim 1 , wherein the higher layer signal is a radio resource control (RRC) message.
3. The method of claim 1 , wherein the PUSCH is scheduled by the uplink DCI format.
4. The method of claim 1 , wherein the multi-bit field includes 2 bits.
5. A base station (BS), comprising:
a radio frequency (RF) unit configured to transmit and receive radio signals; and
a processor coupled to the RF unit,
wherein the processor is configured to:
control the RF unit to transmit, to a user equipment (UE), an uplink downlink control information (DCI) format, and
control the RF unit to receive, from the UE, aperiodic CSI through a physical uplink shared channel (PUSCH) if the BS triggers an aperiodic CSI report using a CSI request field included in the uplink DCI format,
wherein the CSI request field is either a 1-bit field or a multi-bit field,
wherein, when the UE is configured with only one cell, the CSI request field included in the uplink DCI format is the 1-bit field,
wherein, when the UE is configured with more than one channel state information-reference signal (CSI-RS), the CSI request field included in the uplink DCI format is the multi-bit field,
wherein, when the CSI request field is the multi-bit field, the CSI request field has a value among a plurality of candidate values,
wherein the plurality of candidate values comprises a first value which triggers an aperiodic CSI report for a first set of reference signals and a second value which triggers an aperiodic CSI report for a second set of reference signals, and
wherein the first set of reference signals and the second set of reference signals are configured by a higher layer signal.
6. The BS of claim 5 , wherein the higher layer signal is a radio resource control (RRC) message.
7. The BS of claim 5 , wherein the PUSCH is scheduled by the uplink DCI format.
8. The BS of claim 5 , wherein the multi-bit field includes 2 bits.