Uplink multi-antenna transmission method in wireless communication system and apparatus therefor

A user equipment (UE) configured to transmit an uplink signal to a base station (BS) in a wireless communication system, the UE comprising:

• a radio frequency (RF) unit;
• at least one processor;
• and
• at least one computer memory operably connectable to the at least one processor and storing instructions that, when executed, cause the at least one processor to perform operations comprising:
• performing a plurality of transmissions, to the BS, of a plurality of sounding references signals (SRSs);
• receiving, from the BS and based on the transmitted plurality of SRSs, downlink control information (DCI) for a transmission of the uplink signal;
• determining a precoder and a rank for the transmission of the uplink signal based on the DCI;
• and
• transmitting, to the BS, the uplink signal by using the rank and the precoder,
• wherein:
• in a first scenario for transmitting the uplink signal:
• (i) the DCI comprises a rank indicator (RI), and (ii) the UE determines the precoder and the rank based on the DCI which comprises the RI, and
• in a second scenario for transmitting the uplink signal:
• (i) the UE transmits the plurality of SRSs as a plurality of beamformed SRSs, (ii) the DCI comprises information related to a SRS antenna port, but the DCI does not include the RI, and (iii) the UE determines the precoder and the rank based on the information related to the SRS antenna port.

A processing apparatus configured to control a user equipment (UE) to transmit an uplink signal to a base station (BS) in a wireless communication system, the processing apparatus comprising:

• at least one processor;
• and
• at least one computer memory operably connectable to the at least one processor and storing instructions that, when executed, cause the at least one processor to perform operations comprising:
• performing a plurality of transmissions, to the BS, of a plurality of sounding references signals (SRSs);
• receiving, from the BS and based on the transmitted plurality of SRSs, downlink control information (DCI) for a transmission of the uplink signal;
• determining a precoder and a rank for the transmission of the uplink signal based on the DCI;
• and
• transmitting, to the BS, the uplink signal by using the rank and the precoder,
• wherein:
• in a first scenario for transmitting the uplink signal:
• (i) the DCI comprises a rank indicator (RI), and (ii) the UE determines the precoder and the rank based on the DCI which comprises the RI, and
• in a second scenario for transmitting the uplink signal:
• (i) the UE transmits the plurality of SRSs as a plurality of beamformed SRSs, (ii) the DCI comprises information related to a SRS antenna port, but the DCI does not include the RI, and (iii) the UE determines the precoder and the rank based on the information related to the SRS antenna port.