TECHNICAL FIELD

The present invention relates to a wireless communication system, and more particularly, to method for an uplink multi input multi output (MIMO) transmission and an apparatus for supporting the same.

BACKGROUND ART

Mobile communication systems have been developed to provide voice services, while guaranteeing user activity. Service coverage of mobile communication systems, however, has extended even to data services, as well as voice services, and currently, an explosive increase in traffic has resulted in shortage of resource and user demand for a high speed services, requiring advanced mobile communication systems.

The requirements of the next-generation mobile communication system may include supporting huge data traffic, a remarkable increase in the transfer rate of each user, the accommodation of a significantly increased number of connection devices, very low end-to-end latency, and high energy efficiency. To this end, various techniques, such as small cell enhancement, dual connectivity, massive Multiple Input Multiple Output (MIMO), in-band full duplex, non-orthogonal multiple access (NOMA), supporting super-wide band, and device networking, have been researched.

SUMMARY

An object of the present invention is to propose a method for uplink multi input multi output (MIMO) transmission.

Further, an object of the present invention is to propose a method for configuring downlink control information (DCI) for multi input multi output (MIMO) transmission.

Further, an object of the present invention is to propose a method for transmitting an uplink reference signal which becomes a base for uplink multi input multi output (MIMO) transmission and a method for controlling the same.

Technical objects to be achieved by the present invention are not limited to the aforementioned technical objects, and other technical objects not described above may be evidently understood by a person having ordinary skill in the art to which the present invention pertains from the following description.

In an aspect of the present invention, a method for performing uplink transmission by a user equipment (UE) in a wireless communication system may include: receiving downlink control information (DCI) including sounding reference signal (SRS) resource indication (SRI) and precoding indication from a base station; and transmitting an uplink to the base station by applying precoding indicated by the precoding indication on an antenna port of an SRS transmitted in an SRS resource selected by the SRI.

In another aspect of the present invention, a user equipment (UE) performing uplink transmission in a wireless communication system may include: a radio frequency (RF) unit for transmitting and receiving a radio signal; and a processor controlling the RF unit, and the processor may be configured to receive downlink control information (DCI) including sounding reference signal (SRS) resource indication (SRI) and precoding indication from a base station, and transmit an uplink to the base station by applying precoding indicated by the precoding indication on an antenna port of an SRS transmitted in an SRS resource selected by the SRI.

Preferably, the method may further include transmitting a precoded SRS for each of one or more SRS resources configured for the UE to the base station.

Preferably, a beamforming vector and/or beamforming coefficient applied for transmission of the precoded SRS may be configured through control channel signaling by the base station or arbitrarily determined by the UE.

Preferably, the beamforming vector and/or beamforming coefficient applied for the precoded SRS transmission in the SRS resource may be determined based on a beamforming vector and/or beamforming coefficient used for reception of a downlink reference signal (DL RS).

Preferably, the DL RS may be a channel state information reference signal (CSI-RS), and a CSI-RS resource used for determining the beamforming vector and/or beamforming coefficient applied for the precoded SRS transmission may be indicated by the base station.

Preferably, an independent beamforming vector and/or beamforming coefficient may be applied for each subband for the precoded SRS transmission in the SRS resource.

Preferably, the beamforming vector and/or beamforming coefficient applied for the precoded SRS transmission for each subband may be determined based on a beamforming vector and/or beamforming coefficient used for reception of a downlink reference signal (DL RS).

Preferably, the DL RS may be a channel state information reference signal (CSI-RS), and a CSI-RS resource used for determining the beamforming vector and/or beamforming coefficient applied for the precoded SRS transmission may be indicated by the base station.

Preferably, the DCI may further include a rank indication for the uplink transmission.

Preferably, the number of ranks for the uplink transmission may be determined as the number of antenna ports of the SRS transmitted in the SRS resource selected by the SRI.

Preferably, the precoding indication may be divided into first precoding indication and second precoding indication, and the second precoding indication may be jointly encoded with uplink resource allocation information scheduled to the UE.

Advantageous Effects

According to the embodiment of the present invention, frequency selective optimized precoding may be supported even in the uplink.

Further, according to the embodiment of the present invention, uplink transmission throughput may be enhanced by applying optimized precoding for each uplink subband (resource block group).

Further, according to the embodiment of the present invention, overhead of downlink control information related to the uplink for applying uplink subband (resource block group) precoding may be minimized.

Effects which may be obtained by the present invention are not limited to the aforementioned effects, and other technical effects not described above may be evidently understood by a person having ordinary skill in the art to which the present invention pertains from the following description.

