KR20230133166A - Wireless communication device for transmitting and receiving data using CSI feedback and operating method thereof - Google Patents

Abstract

A method of operating a user equipment (UE) according to the technical idea of the present disclosure includes the steps of transmitting a sounding reference signal (SRS) to a base station, and receiving a first reference signal to which a first precoder is applied from the base station. , at least one of the relationship between the first precoder and a second precoder applied to the first physical downlink shared channel (PDSCH) by the base station based on the SRS and a channel estimated using the first reference signal Based on this, generating feedback information including at least one of a rank indicator (RI) and a channel quality indicator (CQI), transmitting the generated feedback information to the base station, and the second precoder, the RI, and the It includes receiving a second PDSCH to which at least one of the CQIs is applied.

Description

Wireless communication device for transmitting and receiving data using CSI feedback and operating method thereof}

The technical idea of the present disclosure is an invention related to a wireless communication device that transmits and receives data using CSI feedback.

A user equipment (UE) may transmit a sounding reference signal (SRS) to a base station (BS). The base station can estimate the uplink channel between the UE and the base station using the received SRS. The base station can design a precoder for the downlink channel using the estimated uplink channel. Specifically, the base station can design a precoder for the downlink channel using the reciprocity of the estimated uplink channel and time division duplex (TDD) channel.

Additionally, the base station may transmit reference signals to the UE to obtain channel information between the base station and the UE. For example, the base station may transmit a channel state information-reference signal (CSI-RS) to obtain channel information between the base station and the UE. The UE can determine the channel between the base station and the UE through the CSI-RS received from the base station. The UE can report feedback information about the identified channel to the base station. Feedback information may include a precoding matrix indicator (PMI), a rank indicator (RI), and a channel quality indicator (CQI). The base station can design a precoder using the received feedback information.

The base station can transmit a PDSCH to the UE using an SRS-based precoder. Even if the base station uses an SRS-based precoder, there is a need for a method to increase the throughput of the PDSCH by utilizing CSI feedback.

The problem to be solved by the technical idea of the present disclosure is to provide a wireless communication device that transmits and receives data using CSI feedback and a method of operating the same.

In order to achieve the above object, in a method of operating a UE (user equipment) according to the technical idea of the present disclosure, transmitting a sounding reference signal (SRS) to a base station, a first precoder to which a first precoder is applied from the base station Receiving a reference signal, a relationship between the first precoder and a second precoder applied to a first physical downlink shared channel (PDSCH) by the base station based on the SRS, and the first reference signal Generating feedback information including at least one of a rank indicator (RI) and a channel quality indicator (CQI) based on at least one of the channels estimated using, transmitting the generated feedback information to the base station, and It includes receiving a second PDSCH to which at least one of the second precoder, the RI, and the CQI is applied.

In a method of operating a base station according to another aspect of the technical idea of the present disclosure, receiving a sounding reference signal (SRS) from a wireless communication device, generating a second precoder based on the SRS, Transmitting a first reference signal to which a first precoder is applied to the wireless communication device, determining a precoding matrix indicator (PMI) candidate group based on the first precoder and the second precoder, Receiving feedback information for the first reference signal including at least one of a rank indicator (RI) and a channel quality indicator (CQI) and a PDSCH to which at least one of the first precoder, the RI, and the CQI is applied ( It includes the step of transmitting a physical downlink shared channel.

In a user equipment (UE) according to another aspect of the technical idea of the present disclosure, transmitting a sounding reference signal (SRS) to a base station and receiving a first reference signal to which a first precoder is applied from the base station. Using the relationship between the first precoder and a second precoder applied to the first physical downlink shared channel (PDSCH) by the base station based on a radio frequency integrated circuit (RFIC) and the SRS and the first reference signal and a processor that generates feedback information including at least one of a rank indicator (RI) and a channel quality indicator (CQI) based on at least one of the estimated channels. The RFIC may transmit the generated feedback information to the base station and receive a second PDSCH to which at least one of the second precoder, the RI, and the CQI is applied.

When the wireless communication device according to an exemplary embodiment of the present disclosure receives data to which a precoder based on sounding reference signal (SRS) switching is applied, the wireless communication device receives CSI (CSI) more suitable for the data transmission channel. channel state information) can be reported.

The wireless communication device according to an exemplary embodiment of the present disclosure can calculate CSI feedback information corresponding to the data transmission channel even when the data transmission channel and the transmission channel of the CSI-RS (channel state information-reference signal) are different.

The effects that can be obtained from the exemplary embodiments of the present disclosure are not limited to the effects mentioned above, and other effects not mentioned are common knowledge in the technical field to which the exemplary embodiments of the present disclosure belong from the following description. It can be clearly derived and understood by those who have it. That is, unintended effects resulting from implementing the exemplary embodiments of the present disclosure may also be derived by those skilled in the art from the exemplary embodiments of the present disclosure.

1A and 1B illustrate a wireless communication system according to an example embodiment of the present disclosure.
Figure 2 is a flowchart showing a method of operating a UE and a base station according to an exemplary embodiment of the present disclosure.
Figure 3 is a flowchart showing a method of operating a UE and a base station according to an exemplary embodiment of the present disclosure.
FIG. 4A is a flowchart showing a method of operating a UE and a base station according to an exemplary embodiment of the present disclosure.
FIG. 4B shows an operation procedure of a UE according to an exemplary embodiment of the present disclosure.
Figure 5A shows an operation procedure of a base station according to an exemplary embodiment of the present disclosure.
Figure 5b shows a QCL-type applicable to an exemplary embodiment of the present disclosure.
Figure 6 shows operation procedures of a UE and a base station according to an exemplary embodiment of the present disclosure.
7A to 7D illustrate TRPs to which example embodiments of the present disclosure are applicable.
Figure 7e shows the operation procedures of UE and TRPs according to an exemplary embodiment of the present disclosure.
Figure 8 is a block diagram showing a wireless communication device according to an exemplary embodiment of the present disclosure.
Figure 9 is a block diagram showing an electronic device according to an exemplary embodiment of the present disclosure.

The base station communicates with the wireless communication device and is the entity that allocates communication network resources to the wireless communication device, including cell, base station (BS), NodeB (NB), eNodB (eNB), and NG RAN (next generation radio). At least one of an access network), a wireless access unit, a base station controller, a node on the network, gNodeB (gNB), a transmission and reception point, a transmission and reception point (TRP), and a remote radio head (RRH). You can.

A wireless communication device is an entity that communicates with a base station or other wireless communication devices, and includes a node, user equipment (UE), next generation UE (NG UE), mobile station (MS), mobile equipment (ME), It may be referred to as a device or terminal.

Additionally, wireless communication devices include smartphones, tablet PCs, mobile phones, video phones, e-book readers, desktop PCs, laptop PCs, netbook computers, PDAs, portable multimedia players (PMPs), MP3 players, medical devices, cameras, or wearables. It may include at least one of the devices. In addition, wireless communication devices include televisions, DVD (digital video disk) players, audio systems, refrigerators, air conditioners, vacuum cleaners, ovens, microwave ovens, washing machines, air purifiers, set-top boxes, home automation control panels, security control panels, and media boxes. It may include at least one of (e.g. Samsung HomeSyncTM, Apple TVTM, or Google TVTM), a game console (e.g. XboxTM, PlayStationTM), an electronic dictionary, an electronic key, a camcorder, or an electronic picture frame. In addition, wireless communication devices may be used in various medical devices (e.g., various portable medical measurement devices (blood sugar monitor, heart rate monitor, blood pressure monitor, or body temperature monitor, etc.), magnetic resonance angiography (MRA), magnetic resonance imaging (MRI), computed tomography (CT), etc. tomography, radiography, or ultrasound, etc.), navigation devices, global navigation satellite system (GNSS), event data recorder (EDR), flight data recorder (FDR), automotive infotainment devices, marine electronic equipment (e.g. marine navigation systems, gyro compasses, etc.), avionics, security devices, head units for vehicles, industrial or domestic robots, drones, ATMs at financial institutions, point of sales (POS) at stores. , or it may include at least one of IoT devices (e.g., light bulbs, various sensors, sprinkler devices, fire alarms, thermostats, street lights, toasters, exercise equipment, hot water tanks, heaters, boilers, etc.). In addition, the wireless communication device may include various types of multi-media systems capable of performing communication functions.

Hereinafter, embodiments of the present invention will be described in detail with reference to the attached drawings.

1A and 1B illustrate a wireless communication system according to an example embodiment of the present disclosure.

1A and 1B, a wireless communication system may include a wireless communication device 120 and a base station 110. Hereinafter, in this disclosure, the wireless communication device 120 is referred to as UE 120. For convenience of description, the wireless communication system is shown as including only one base station 110 and one UE 120, but this is only an exemplary embodiment and is not limited to this, and may include a various number of base stations and UEs. A wireless communication system may be implemented.

The base station 110 is connected to the UE 120 through a wireless channel and can provide various communication services. The base station 110 can provide services through a shared channel for all user traffic, and can perform scheduling by collecting status information such as buffer status, available transmission power status, and channel status of the UE 120. there is. A wireless communication system can support beam forming technology using Orthogonal Frequency Division Multiplexing (OFDM) as a wireless access technology. Additionally, the wireless communication system may support an Adaptive Modulation & Coding (AMC) method that determines a modulation scheme and channel coding rate according to the channel status of the UE 120.

Additionally, a wireless communication system can transmit and receive signals using a wide frequency band that exists in a frequency band of 6 GHz or higher. For example, a wireless communication system can increase data transmission rate by using a millimeter wave band, such as the 28 GHz band or the 60 GHz band. At this time, because the millimeter wave band has a relatively large signal attenuation per distance, a wireless communication system can support transmission and reception based on a directional beam generated using multiple antennas to secure coverage. The wireless communication system may be a system that supports MIMO (Multiple Input, Multiple Output), and accordingly, the base station 110 and the UE 120 may support beam forming technology. Beam forming technology can be divided into digital beam forming, analog beam forming, hybrid beam forming, etc., and hereinafter, the wireless communication system will describe the idea of the present technology focusing on embodiments that support the hybrid beam forming technology, but this technology It will be fully understood that it can be applied to other beam forming technologies as well.

Referring to FIG. 1A, the base station 110 may transmit a CSI-RS to the UE 120. The UE 120 can estimate the channel between the base station 110 and the UE 120 using CSI-RS. The UE 120 may use the estimated channel to generate CSI feedback information including at least one of a rank indicator (RI), a precoding matrix indicator (PMI), and channel quality information (CQI). UE 120 may transmit feedback information to base station 110.

Referring to FIG. 1B, the UE 120 may transmit a sounding refrence signal (SRS) to the base station 110. The base station 110 can estimate the channel between the base station 110 and the UE 120 using SRS in a time division duplex (TDD) situation. The base station 110 can design the precoder to maximize the capacity of the estimated channel. The base station 110 can transmit the PDSCH to the UE 120 using the designed precoder.

When the base station 110 transmits a PDSCH to the UE 120 using an SRS-based precoder, scheduling for the PDSCH can be performed by additionally using CSI feedback information.

As an example, the base station 110 calculates information about the relationship between the CSI-RS precoder and the SRS-based precoder to use CSI feedback information when transmitting a PDSCH using an SRS-based precoder and sends the information to the UE (120). ) can be sent to. Additionally, the UE 120 may generate CSI feedback information corresponding to the PDSCH based on the received information.

As another example, the UE 120 can predict the relationship between the PDSCH precoder and the CSI-RS precoder by measuring the beamforming gain for the PDSCH and the beamforming gain for the CSI-RS. The UE 120 may generate CSI feedback information corresponding to the PDSCH using relationship information between the precoder of the PDSCH and the precoder of the CSI-RS. This will be explained in more detail through the following examples.

Figure 2 is a flowchart showing a method of operating a UE and a base station according to an exemplary embodiment of the present disclosure.

Referring to FIG. 2, in step S201, the UE 120 may transmit an SRS to the base station 110. Base station 110 may receive SRS from UE 120. The base station 110 can estimate the uplink channel and downlink channel between the base station 110 and the UE 120 using the received SRS. Specifically, in a TDD situation, the base station 110 uses SRS (SRS switching) based on reciprocity to transmit the estimated uplink channel between the base station 110 and the UE 120 to the base station 110. It can be considered a downlink channel between UEs 120. The base station can design the first precoder based on SRS, as will be described later.

In step S203, the base station 110 may design a first precoder applied to the first PDSCH. Specifically, the base station 110 may design the first precoder to maximize the capacity of the channel estimated using SRS.

The first precoder may be a precoder that is not based on a codebook. As an example, the first precoder may be composed of the eigenvector (Eigen-vetor) of the channel between the base station 110 and the UE 120. The first precoder may have higher resolution than the codebook-based precoder. Accordingly, when the first precoder is used for data transmission, data throughput may be higher than when the codebook-based precoder is used for data transmission.

The base station 110 may design the first precoder to maximize a metric such as mean of the mutual information per coded bit (MMIB) using the estimated channel. The base station 110 may design the first precoder to maximize various metrics and is not limited to the above-described embodiments.

In step S205, the base station 110 may determine the beamforming gain. The base station 110 may calculate the beamforming gain for a physical downlink shared channel (PDSCH) to which the first precoder based on SRS is applied. Specifically, the base station 110 may calculate the first beamforming gain obtained by the UE 120 when the UE 120 receives a PDSCH to which an SRS-based precoder is applied.

Meanwhile, the base station 110 may transmit a CSI-RS to which the second precoder is applied to the UE 120. The base station 110 may calculate the second beamforming gain obtained by the UE 120 when the UE 120 receives a CSI-RS to which the second precoder is applied. The first precoder and the second precoder may be different.

The base station 110 may calculate a first beamforming gain for the first precoder that maximizes the channel capacity of the channel estimated based on SRS and a second beamforming gain for the second precoder applied to CSI-RS. .

In step S207, the UE 120 may receive beamforming gain information from the base station 110. The base station 110 may transmit first beamforming gain information for the first precoder based on SRS to the UE 120. Additionally, the base station 110 may transmit second beamforming gain information for the second precoder applied to the CSI-RS to the UE 120.

The base station 110 provides the UE 120 with beamforming gain information including first beamforming gain information for the first precoder based on SRS and second beamforming gain information for the second precoder applied to CSI-RS. can be transmitted to the UE 120. For example, the base station 110 may transmit information about the ratio of the first beamforming gain and the second beamforming gain to the UE 120. The ratio of the first beamforming gain and the second beamforming gain can be expressed as follows.

[Equation 1]

In equation 1, May refer to the ratio (or difference) between the first beamforming gain and the second beamforming gain. May refer to a channel between the UE 120 and the base station 110. May refer to a precoder that maximizes the capacity of the channel estimated based on SRS. May refer to the second precoder used when the base station transmits CSI-RS. may refer to the number of layers of data transmitted by the base station. May refer to the number of antenna ports of CSI-RS.

Beamforming gain information including the ratio of the above-described first beamforming gain and second beamforming gain may be referred to as a beamforming gain offset. The beamforming gain offset may include the ratio of the beamforming gain of the PDSCH resource element and the beamforming gain of the non-zero power (NZP) CSI-RS resource element. The beamforming gain offset may have a value in dB units.

The base station 110 provides beamforming gain information to the UE ( 120). For example, the base station 110 may transmit a radio resource control (RRC) signal including beamforming gain information to the UE 120. As a specific example, the beamforming gain offset may be included in the NZP-CSI-RS-Resource information element.

In step S209, the UE 120 may receive a CSI-RS to which the second precoder is applied from the base station 110. The UE 120 can estimate the channel between the base station 110 and the UE 120 using the received CSI-RS.

In step S211, the UE 120 may generate feedback information based on the relationship between the first precoder and the second precoder. The relationship between the first precoder and the second precoder may refer to the ratio between the first beamforming gain of the first precoder and the second beamforming gain of the second precoder. For example, the UE 120 may generate CSI-RS feedback information using the received beamforming gain information.

The UE 120 may calculate at least one of a precoding matrix indicator (PMI), a rank, and a channel quality indicator (CQI) using the received beamforming gain information and the estimated channel. For example, the UE 120 may calculate the rank and PMI that maximize the estimated channel capacity, and the rank and PMI may be expressed as Equation 2 below.

[Equation 2]

In equation 2, May refer to the ratio (or difference) between the first beamforming gain and the second beamforming gain. may refer to the rank that the UE 120 will report using a rank indicator (RI). May refer to the number of antenna ports of CSI-RS. May refer to a PMI codebook with rank L. is described later in Equation 3. Channel capacity is described later in Equation 4.

Regarding Equation 2, the received signal of CSI-RS can be expressed as Equation 3 below.

[Equation 3]

In equation 3, May refer to a CSI-RS received signal. May refer to a channel between the UE 120 and the base station 110. May refer to the precoder used by the base station for CSI-RS transmission. may refer to noise included in the received signal. May refer to the product of the channel between the UE 120 and the base station 110 and the precoder used for CSI-RS transmission. UE 120 is and cannot be received separately. Accordingly, the UE 120 The value of can be estimated.

PMI codebook with rank L When this is applied, the channel capacity can be expressed as Equation 4 below.

[Equation 4]

In step S213, the UE 120 may transmit feedback information to the base station 110. For example, the UE 120 may transmit feedback information including beamforming gain information and a rank indicator (RI) and CQI calculated using the estimated channel to the base station 110. The CSI report of this disclosure is described based on the subband CSI report. However, the CSI report of this disclosure can also be applied to a wideband CSI report.

In step S215, the base station 110 may perform scheduling for the second PDSCH. As described above, the base station 110 may perform scheduling for the second PDSCH using at least one of the first precoder based on SRS and feedback information received from the UE 120. For example, the base station 110 may perform scheduling for the second PDSCH using at least one of the first precoder based on SRS and the RI and CQI received from the UE 120. The base station 110 can determine the rank for the second PDSCH using the received RI. The base station 110 may determine a modulation and coding scheme (MCS) for the second PDSCH using the received CQI. Accordingly, the base station 110 can determine at least one of the rank and CQI suitable for the UE 120.

In step S217, the UE 120 may receive the second PDSCH from the base station 110.

Figure 3 is a flowchart showing a method of operating a UE and a base station according to an exemplary embodiment of the present disclosure.

Referring to FIG. 3, in step S301, the UE 120 may transmit an SRS to the base station 110. Base station 110 may receive SRS from UE 120. The base station 110 can estimate the uplink channel and downlink channel between the base station 110 and the UE 120 using the received SRS. Specifically, in a TDD situation, the base station 110 may regard the uplink channel between the base station 110 and the UE 120 estimated using SRS based on reciprocity as a downlink channel. The base station can design the first precoder based on SRS, as will be described later.

In step S303, the base station 110 may design a first precoder applied to the first PDSCH. Specifically, the base station 110 may design the first precoder to maximize the capacity of the channel estimated using SRS.

The first precoder may be a precoder that is not based on a codebook. As an example, the first precoder may be composed of the eigenvector of the channel between the base station 110 and the UE 120. The first precoder may have higher resolution than the codebook-based precoder. Accordingly, when the first precoder is used for data transmission, data throughput may be higher than when the codebook-based precoder is used for data transmission.

Base station 110 may design the first precoder to maximize a metric such as MMIB using the estimated channel. The base station 110 may design the first precoder to maximize various metrics and is not limited to the above-described embodiments.

In step S305, the UE 120 may receive the first PDSCH from the base station 110. The base station 110 may apply the first precoder to the first PDSCH. The base station 110 may transmit the first PDSCH to which the first precoder is applied to the UE 120.

In step S307, the UE 120 may measure the beamforming gain for the first precoder. Specifically, the UE 120 may measure the beamforming gain of the first PDSCH to which the first precoder based on SRS is applied. For example, the UE 120 may measure the beamforming gain of the first PDSCH by measuring the received power of the first PDSCH.

In step S309, the UE 120 may receive a CSI-RS to which the second precoder is applied from the base station 110. The first precoder and the second precoder may be different. The UE 120 can estimate the channel between the base station 110 and the UE 120 using the received CSI-RS.

In step S311, the UE 120 may measure the beamforming gain for the second precoder. Specifically, the UE 120 can measure the beamforming gain of the CSI-RS to which the second precoder is applied. For example, the UE 120 may measure the beamforming gain of the CSI-RS by measuring the received power of the CSI-RS.

The UE 120 may estimate the ratio of the beamforming gain for the first precoder based on SRS and the beamforming gain for the second precoder applied to CSI-RS. Specifically, the UE 120 may estimate the ratio of beamforming gains using the measured beamforming gain of the first precoder and the measured beamforming gain of the second precoder. The ratio of beamforming gain can be expressed as Equation 1 described above.

In step S313, the UE 120 may generate feedback information based on the relationship between the first precoder and the second precoder. The relationship between the first precoder and the second precoder may refer to the ratio between the first beamforming gain of the first precoder and the second beamforming gain of the second precoder. For example, the UE 120 may generate CSI-RS feedback information using the measured beamforming gain of the first precoder and the measured beamforming gain of the second precoder. Additionally, the UE 120 may generate CSI-RS feedback information using ratio information between the measured beamforming gain of the first precoder and the measured beamforming gain of the second precoder.

The UE 120 may calculate at least one of PMI, RI, and CQI using the measured beamforming gain and the estimated channel. The rank and PMI can be calculated using the channel and beamforming gain information estimated by the UE 120, and the rank and PMI can be expressed as Equation 2 described above.

In step S315, the UE 120 may transmit feedback information to the base station 110. For example, the UE 120 may transmit feedback information including a rank indicator (RI) and a CQI calculated using the measured beamforming gain information and the estimated channel to the base station 110.

In step S317, the base station 110 may perform scheduling for the second PDSCH. As described above, the base station 110 may perform scheduling for the second PDSCH using at least one of the first precoder based on SRS and feedback information received from the UE 120. For example, the base station 110 may perform scheduling for the second PDSCH using at least one of the first precoder based on SRS and the RI and CQI received from the UE 120. The base station 110 can determine the rank for the second PDSCH using the received RI. The base station 110 may determine a modulation coding scheme (MCS) for the second PDSCH using the received CQI. Accordingly, the base station 110 can determine at least one of the rank and CQI suitable for the UE 120.

In step S319, the UE 120 may receive the second PDSCH from the base station 110.

FIG. 4A is a flowchart showing a method of operating a UE and a base station according to an exemplary embodiment of the present disclosure.

Referring to FIG. 4A, in step S401a, the UE 120 may transmit an SRS to the base station 110. Base station 110 may receive SRS from UE 120. The base station 110 can estimate the uplink channel and downlink channel between the base station 110 and the UE 120 using the received SRS. Specifically, in a TDD situation, the base station 110 uses SRS based on reciprocity to convert the estimated uplink channel between the base station 110 and the UE 120 into a downlink channel between the base station 110 and the UE 120. can be considered. The base station can design the first precoder based on SRS, as will be described later.

In step S403a, the base station 110 may design a first precoder applied to the first PDSCH. Specifically, the base station 110 may design the first precoder to maximize the capacity of the channel estimated using SRS.

The first precoder may be a precoder that is not based on a codebook. As an example, the first precoder may be composed of the eigenvector of the channel between the base station 110 and the UE 120. The first precoder may have higher resolution than the codebook-based precoder. Accordingly, when the first precoder is used for data transmission, data throughput may be higher than when the codebook-based precoder is used for data transmission.

Base station 110 may design the first precoder to maximize a metric such as MMIB using the estimated channel. The base station 110 may design the first precoder to maximize various metrics and is not limited to the above-described embodiments.

In step S405a, the UE 120 may receive the first PDSCH from the base station 110. The base station 110 may apply the first precoder to the first PDSCH. The base station 110 may transmit the first PDSCH to which the first precoder is applied to the UE 120.

In step S407a, the UE 120 may measure the beamforming gain for the first precoder. Specifically, the UE 120 may measure the beamforming gain of the first PDSCH to which the first precoder based on SRS is applied. For example, the UE 120 may measure the beamforming gain of the first PDSCH by measuring the received power of the first PDSCH.

In step S409a, the UE 120 may receive a CSI-RS to which the second precoder is applied from the base station 110. The first precoder and the second precoder may be different. The UE 120 can estimate the channel between the base station 110 and the UE 120 using the received CSI-RS.

In step S411a, the UE 120 may measure the beamforming gain for the second precoder. Specifically, the UE 120 can measure the beamforming gain of the CSI-RS to which the second precoder is applied. For example, the UE 120 may measure the beamforming gain of the CSI-RS by measuring the received power of the CSI-RS.

The UE 120 may estimate the ratio of the beamforming gain for the first precoder based on SRS and the beamforming gain for the second precoder applied to CSI-RS. Specifically, the UE 120 may estimate the ratio of beamforming gains using the measured beamforming gain of the first precoder and the measured beamforming gain of the second precoder. The ratio of beamforming gain can be expressed as Equation 1 described above.

In step S413a, the UE 120 may transmit a channel alignment request message to the base station 110. Specifically, when the measured beamforming gain of the first PDSCH and the beamforming gain of the CSI-RS are different, the UE 120 may transmit a channel alignment request message to the base station 110. The UE 120 may request the base station 110 to change the precoder of the CSI-RS by transmitting a channel alignment request message. For example, the UE 120 may request the base station 110 to apply the first precoder of the first PDSCH to the CSI-RS by transmitting a channel alignment request message.

When receiving a channel alignment request message from the UE 120, the base station 110 may apply the first precoder to the CSI-RS. Additionally, when receiving a channel alignment request message from the UE 120, the base station 110 can design a precoder for the PDSCH without using the PMI codebook. The channel alignment request message may be referred to as a non-PMI based feedback request message. The UE 120 may transmit a non-PMI based feedback request message to the base station 110 using any one of all signaling methods including RRC, MAC CE, and DCI. For example, the UE 120 may transmit a UE Assistance Information message including a non-PMI based feedback request message to the base station 110. UE Assistance Information may be an RRC signaling parameter.

In step S415a, the base station 110 may determine the beam of the CSI-RS. For example, when receiving a channel alignment request message from the UE 120, the base station 110 may apply the precoder of the first PDSCH transmitted to the UE 120 to the CSI-RS.

In step S417a, the UE 120 may receive a CSI-RS to which the first precoder is applied from the base station 110. When receiving a CSI-RS with non-PMI configured, the UE 120 may determine that the precoders of the CSI-RS and the PDSCH are the same.

In step S419a, the UE 120 may generate feedback information using the CSI-RS to which the first precoder is applied. For example, the UE 120 may estimate the channel between the base station 110 and the UE 120 using CSI-RS to which the first precoder is applied. And, the UE 120 may calculate feedback information including at least one of RI and CQI that maximizes the estimated channel.

In step S421a, the UE 120 may transmit feedback information to the base station 110. The UE 120 may transmit feedback information including the calculated rank indicator (RI) and CQI to the base station 110.

In step S423a, the base station 110 may perform scheduling for the second PDSCH. As described above, the base station 110 may perform scheduling for the second PDSCH using at least one of the first precoder based on SRS and feedback information received from the UE 120. For example, the base station 110 may perform scheduling for the second PDSCH using at least one of the first precoder based on SRS and the RI and CQI received from the UE 120. The base station 110 can determine the rank for the second PDSCH using the received RI. The base station 110 may determine a modulation coding scheme (MCS) for the second PDSCH using the received CQI. Accordingly, the base station 110 can determine at least one of the rank and CQI suitable for the UE 120.

In step S425a, the UE 120 may receive the second PDSCH from the base station 110.

FIG. 4B shows an operation procedure of a UE according to an exemplary embodiment of the present disclosure. Specifically, FIG. 4B shows an example of an operation procedure of the UE 120 in a situation in which the UE 120 measures the beamforming gain of the first precoder and the beamforming gain of the second precoder in FIG. 4A.

In step S401b, the UE 120 may measure the beamforming gain of each PDSCH and CSI-RS. The UE 120 can measure the received power of the first PDSCH and the received power of the CSI-RS, respectively. The UE 120 may calculate the beamforming gain of the first precoder by measuring the received power of the first PDSCH. The UE 120 may calculate the beamforming gain of the second precoder by measuring the CSI-RS received power.

In step S403b, the UE 120 may check whether the beamforming gain of the PDSCH and the beamforming gain of the CSI-RS are different.

In step S405b, the UE 120 may transmit a channel alignment request message when the beamforming gain of the PDSCH and the beamforming gain of the CSI-RS are different (Y in FIG. 4B). The UE 120 may request the base station 110 to apply the first precoder to the CSI-RS by transmitting a channel alignment request message.

In step S407b, if the beamforming gain of the PDSCH and the beamforming gain of the CSI-RS are the same (N in FIG. 4b), the UE 120 determines RI and CQI based on the received CSI-RS. You can. In this case, the precoder of CSI-RS can already be considered the same as the precoder of PDSCH.

Figure 5A shows an operation procedure of a base station according to an exemplary embodiment of the present disclosure.

Referring to FIG. 5A, in step S501, the UE 120 may transmit an SRS to the base station 110. Base station 110 may receive SRS from UE 120. The base station 110 can estimate the uplink channel and downlink channel between the base station 110 and the UE 120 using the received SRS. Specifically, in a TDD situation, the base station 110 uses SRS based on reciprocity to convert the estimated uplink channel between the base station 110 and the UE 120 into a downlink channel between the base station 110 and the UE 120. can be considered. The base station can design the first precoder based on SRS switching, as described later.

In step S503, the base station 110 may design a first precoder applied to the first PDSCH. Specifically, the base station 110 may design the first precoder to maximize the capacity of the estimated channel using SRS. The first precoder may be a precoder that is not based on a codebook. As an example, the first precoder may be composed of the eigenvector of the channel between the base station 110 and the UE 120. The first precoder may have higher resolution than the codebook-based precoder. Accordingly, when the first precoder is used for data transmission, data throughput may be higher than when the codebook-based precoder is used for data transmission.

Base station 110 may design the first precoder to maximize a metric such as MMIB using the estimated channel. The base station 110 may design the first precoder to maximize various metrics and is not limited to the above-described embodiments.

In step S505, the base station 110 may determine the beam of the CSI-RS. For example, the base station 110 may apply the first precoder to CSI-RS. In this case, the base station 110 may inform the UE 120 that the first precoder used for PDSCH transmission and the precoder used for CSI-RS transmission have the same beamforming gain.

In step S507, the UE 120 may receive beamforming gain information from the base station 110. For example, the UE 120 may receive information from the base station 110 that the first precoder used for PDSCH transmission and the precoder used for CSI-RS transmission have the same beamforming gain. Beamforming gain information can be expressed as Equation 5 below.

[Equation 5]

The UE 120 may receive this beamforming gain information through higher layer signaling related to the transmission configuration information (TCI) state. For example, the UE 120 may receive this beamforming gain information through quasi-co-location (QCL) type signaling, which is a higher layer parameter.

In step S509, the UE 120 may receive a CSI-RS to which the first precoder is applied from the base station 110. The UE 120 may confirm that the precoder applied to the first PDSCH and the precoder applied to the CSI-RS are the same based on QCL-type information including QCL-type-E received from the base station 110. there is. The UE 120 can estimate the channel between the base station 110 and the UE 120 using the received CSI-RS.

In step S511, the UE 120 may generate feedback information using the CSI-RS to which the first precoder is applied. UE 120 may calculate at least one of PMI, RI, and CQI. The rank and PMI can be calculated using the channel and beamforming gain information estimated by the UE 120, and the rank and PMI can be expressed as Equation 2 described above.

In step S513, the UE 120 may transmit feedback information to the base station 110. For example, the UE 120 may transmit feedback information including beamforming gain information and a rank indicator (RI) and CQI calculated using the estimated channel to the base station 110.

In step S515, the base station 110 may perform scheduling for the second PDSCH. As described above, the base station 110 may perform scheduling for the second PDSCH using at least one of the first precoder based on SRS and feedback information received from the UE 120. For example, the base station 110 may perform scheduling for the second PDSCH using at least one of the first precoder based on SRS and the RI and CQI received from the UE 120. The base station 110 can determine the rank for the second PDSCH using the received RI. The base station 110 can determine the MCS for the second PDSCH using the received CQI. Accordingly, the base station 110 can determine at least one of the rank and CQI suitable for the UE 120.

In step S517, the UE 120 may receive the second PDSCH from the base station 110.

Figure 5b shows a QCL-type applicable to an exemplary embodiment of the present disclosure.

FIG. 5B specifically shows an example of the quasi-co-location (QCL) type described above in step S507 of FIG. 5A.

Referring to Figure 5b, the channel characteristics of QCL-Type-A include Doppler shift, Doppler spread, average delay, and delay spread. Channel characteristics of QCL-Type-B include Doppler shift and Doppler spread. Channel characteristics of QCL-Type-C include Doppler shift and average delay. Channel characteristics of QCL-Type-D include Spatial Rx parameters. QCL-Type-D may mean that a wireless communication device shares spatial Rx parameters obtained from a source signal with a target signal. The source signal may be referred to as a source channel. The target signal may be referred to as a target channel. Channel characteristics of QCL-Type-E may include beamforming gain parameters. QCL-type-E may include the sameness of the beamforming gain of the reference signal precoder and the beamforming gain of the PDSCH precoder.

Hereinafter, transmission configuration indication (TCI) will be described. The base station can inform the terminal that it transmits the PDSCH and PDCCH (physical downlink control channel) using the same beam as the reference signal by signaling the TCI state. That is, the base station may inform that it transmits PDSCH and PDCCH based on the same spatial filter as a specific reference signal. TCI status may include information about reference signals. For example, the TCI state may include information about at least one of a synchronization signal block (SSB) and a channel state information-reference signal (CSI-RS). The base station can inform the terminal which TCI the PDSCH and PDCCH are related to through TCI status signaling.

Figure 6 shows operation procedures of a UE and a base station according to an exemplary embodiment of the present disclosure.

Referring to FIG. 6, in step S601, the UE 120 may transmit an SRS to the base station 110. Base station 110 may receive SRS from UE 120. The base station 110 can estimate the uplink channel and downlink channel between the base station 110 and the UE 120 using the received SRS. Specifically, in a TDD situation, the base station 110 uses SRS based on reciprocity to convert the estimated uplink channel between the base station 110 and the UE 120 into a downlink channel between the base station 110 and the UE 120. can be considered. The base station can design the first precoder based on SRS switching, as described later.

In step S603, the base station 110 may determine a precoder. The base station 110 may design a first precoder applied to the first PDSCH. Specifically, the base station 110 may design the first precoder to maximize the capacity of the estimated channel using SRS. The first precoder may be a precoder that is not based on a codebook. As an example, the first precoder may be composed of the eigenvector of the channel between the base station 110 and the UE 120. The first precoder may have higher resolution than the codebook-based precoder. Accordingly, when the first precoder is used for data transmission, data throughput may be higher than when the codebook-based precoder is used for data transmission.

Base station 110 may design the first precoder to maximize a metric such as MMIB using the estimated channel. The base station 110 may design the first precoder to maximize various metrics and is not limited to the above-described embodiments.

In step S605, the base station 110 may determine a CSI-RS beam. The base station 110 may apply a second precoder that is different from the first precoder to CSI-RS. For example, the base station 110 may calculate a PMI candidate. The PMI candidate group can be expressed as Equation 6 below.

[Equation 6]

In equation 6, May refer to an SRS switching-based precoder for PDSCH transmission. may refer to the PMI codebook. May refer to the precoder that the base station applies to CSI-RS. The base station 110 can calculate each of the SRS switching-based precoder and the precoder applied to CSI-RS and know their values. Referring to Equation 6, the base station 110 can calculate a PMI candidate group that minimizes the difference between the SRS switching-based precoder and the precoder applied to CSI-RS. PMI candidates may have one fixed PMI for each rank.

In addition, the base station 110 may apply a second precoder whose spatial domain characteristics are most similar to the precoder applied to the PDSCH to the CSI-RS based on one of the PMI candidate groups.

In step S607, the UE 120 may receive a PMI candidate group. PMI candidates may be referred to as codebook subset restriction. The base station 110 can fix one PMI for each rank by transmitting a PMI candidate group to the UE 120. The base station 110 can omit the PMI by setting all bitmaps to 0.

In step S609, the UE 120 may receive a CSI-RS to which the second precoder is applied from the base station 110. The UE 120 can estimate the channel between the base station 110 and the UE 120 using the received CSI-RS.

In step S611, the UE 120 may generate feedback information using CSI-RS to which the second precoder is applied. The UE 120 may generate CSI-RS feedback information using the received PMI candidate group information. For example, the UE 120 may calculate at least one of RI and CQI using the received PMI candidate group information and the received CSI-RS.

In step S613, the UE 120 may transmit CSI-RS feedback information to the base station 110. For example, the UE 120 may transmit feedback information including a rank indicator (RI) and a CQI calculated using the PMI codebook to the base station 110.

In step S615, the base station 110 may perform scheduling for the second PDSCH. As described above, the base station 110 may perform scheduling for the second PDSCH using at least one of the first precoder based on SRS and feedback information received from the UE 120. For example, the base station 110 may perform scheduling for the second PDSCH using at least one of the first precoder based on SRS and the RI and CQI received from the UE 120. The base station 110 can determine the rank for the second PDSCH using the received RI. The base station 110 can determine the MCS for the second PDSCH using the received CQI. Accordingly, the base station 110 can determine at least one of the rank and CQI suitable for the UE 120.

In step S617, the UE 120 may receive data from the base station 110.

7A to 7D illustrate TRPs to which example embodiments of the present disclosure are applicable.

Referring to FIG. 7A, UE 120 may be connected to a network through a single transmission and reception point (TRP) 130 and a single beam. Referring to FIG. 7B, the UE 120 may be connected to the network through a plurality of TRPs 130 and 132 and one beam for each TRP. Referring to FIG. 7C, the UE 120 may be connected to the network through a single TRP 130 and multiple beams. Referring to FIG. 7D, the UE 120 may be connected to the network through a plurality of TRPs 130 and 132 and a plurality of beams.

The first TRP 130 and the second TRP 132 may transmit different PDSCHs to the UE 120. Specifically, the first TRP 130 may transmit a first PDSCH to the UE 120, and the first TRP 132 may transmit a second PDSCH to the UE 120. As an example, the first TRP 130 may transmit downlink control information (DCI) to the UE 120 through a physical downlink control channel (PDCCH). And, the first PDSCH and the second PDSCH may be scheduled according to the PDCCH transmitted by the first TRP 130. As another example, the first TRP 130 may transmit a first PDCCH controlling the first PDSCH to the UE 120, and the second TRP 132 may transmit a second PDCCH controlling the second PDSCH to the UE 120. PDCCH can be transmitted. The example embodiments described above in this disclosure may be applied to communication between the UE 120 and a plurality of TRPs 130 and 132.

For example, a plurality of TRPs 130 and 132 may transmit a CSI-RS to the UE 120, and a plurality of TRPs 130 and 132 may transmit the above-described beamforming gain offset to the UE 120. can do.

As another example, the UE 120 may predict the beamforming gain of each PDSCH and CSI-RS for each of the plurality of TRPs 130 and 132. The ratio of beamforming gain to the nth TRP can be expressed as Equation 7 below.

[Equation 7]

In Equation 7, n may refer to the TRP index.

As another example, the UE 120 may transmit the above-described channel alignment request message to each of the plurality of TRPs 130 and 132. That is, the UE 120 may transmit a csi-ReportWithoutPMIRequest message to each of the plurality of TRPs 130 and 132.

As another example, the UE 120 signals to each of the plurality of TRPs 130 and 132 that the beamforming gain of the precoder used for PDSCH transmission and the beamforming gain of the precoder used for CSI-RS transmission are the same. can do. This signaling can be defined as QCL-type as described above. The identity of the beamforming gain can be expressed as Equation 8 below.

[Equation 8]

In Equation 8, n may refer to the index of TRP. The UE 120 can receive signaling about the same beamforming gain and confirm that the same beamforming gain is obtained when receiving the CSI-RS and PDSCH from the plurality of TRPs 130 and 132. Accordingly, the UE 120 may feed back the information calculated using the received CSI-RS to the TRPs 130 and 132, respectively.

As another example, a plurality of TRPs 130 and 132 may each transmit the above-described PMI candidate group to the UE 120. A plurality of TRPs 130 and 132 may apply a precoder whose spatial domain characteristics are most similar to the precoder used for PDSCH transmission to the CSI-RS based on one PMI from the PMI candidate group. The UE 130 may feed back at least one of RI and CQI for each TRP. The PMI candidate group can be expressed as Equation 9 below.

[Equation 9]

In Equation 9, n may refer to the TRP index.

The number of TRPs may vary and is not limited to the above-described embodiment. The example embodiments described above in this disclosure may be applied to communication between the UE 120 and a plurality of radio remote heads (RRHs).

Figure 7e shows the operation procedures of UE and TRPs according to an exemplary embodiment of the present disclosure.

In step S701a, the UE 120 may transmit an SRS to the first TRP 130. In step S701b, the UE 120 may transmit an SRS to the second TRP 132. In step S703a, the first TRP 130 may determine a precoder. Specifically, the first TRP 130 can determine the precoder applied to the PDSCH using SRS. In step S703b, the second TRP 132 may determine a precoder. Specifically, the second TRP 132 can determine the precoder applied to the PDSCH using SRS.

In step S705a, the first TRP 130 may calculate the beamforming gain of the SRS-based precoder and the beamforming gain of the CSI-RS precoder. The first TRP 130 may determine beamforming gain information based on the calculated beamforming gain. In step S705a, the first TRP 130 may calculate the beamforming gain of the SRS-based precoder and the beamforming gain of the CSI-RS precoder. The second TRP 132 may determine beamforming gain information based on the calculated beamforming gain. In step S707a, the UE 120 may receive beamforming gain information from the first TRP 130. In step S707b, the UE 120 may receive beamforming gain information from the second TRP 132. In step S711, the UE 120 may calculate at least one of RI and CQI for each of the first TRP 130 and the second TRP 132 using the CSI-RS received from each. UE 120 may generate CSI feedback information for each TRP.

In step S713a, the UE 120 may transmit a CSI-RS report to the first TRP 130. In step S713b, the UE 120 may transmit a CSI-RS report to the second TRP 130. In step S715a, the first TRP 130 may determine at least one of rank and MCS. The first TRP 130 may schedule the PDSCH using the SRS-based precoder and CSI feedback information received from the UE 120. In step S715b, the second TRP 132 may determine at least one of rank and MCS. The second TRP 132 may schedule the PDSCH using the SRS-based precoder and CSI feedback information received from the UE 120. In step S717a, the first TRP 130 may transmit a PDSCH to the UE 120. In step S717b, the second TRP 132 may transmit a PDSCH to the UE 120. The operation procedure sequence for each TRP of the UE 120 is not limited to the above-described embodiment.

Figure 8 is a block diagram showing a wireless communication device according to an exemplary embodiment of the present disclosure.

Referring to FIG. 8, the wireless communication device 20 (UE 120 of FIG. 1) may include one or more processors 210 and one or more RFICs 220. The processor 210 may control the RFIC 220 and may be configured to implement the operation method and operation flowcharts of the wireless communication device 20 of the present disclosure. The wireless communication device 20 may be equipped with a plurality of antennas, and the RFIC 220 may transmit and receive wireless signals through one or more antennas. At least some of the plurality of antennas may correspond to transmit antennas. The transmission antenna may transmit a wireless signal to an external device (eg, another user equipment (UE) or a base station (BS)) other than the wireless communication device 20. At least some of the remaining antennas among the plurality of antennas may correspond to receiving antennas. The receiving antenna can receive wireless signals from the external device.

As an example, the wireless communication device 20 transmits a sounding reference signal (SRS) to a base station, and receives a first reference signal to which a first precoder is applied from the base station. Based on the relationship between the second precoder applied to the first physical downlink shared channel (PDSCH) by the base station and the first precoder, and the RI ( It may include a processor 210 that generates feedback information including at least one of a rank indicator and a channel quality indicator (CQI).

The RFIC 220 may transmit the generated feedback information to the base station and receive a second PDSCH to which at least one of the second precoder, the RI, and the CQI is applied.

FIG. 9 is a block diagram showing an electronic device 1000 according to an exemplary embodiment of the present disclosure. Referring to FIG. 9, the electronic device 1000 includes a memory 1010, a processor unit 1020, an input/output control unit 1040, a display unit 1050, an input device 1060, and a communication processing unit 1090. It can be included. Here, there may be a plurality of memories 1010. A look at each component is as follows.

The memory 1010 may include a program storage unit 1011 that stores a program for controlling the operation of the electronic device and a data storage unit 1012 that stores data generated during program execution. The data storage unit 1012 may store data necessary for the operation of the application program 1013 and the CSI-RS density determination program 1014. The program storage unit 1011 may include an application program 1013 and a CSI-RS density determination program 1014. Here, the program included in the program storage unit 1011 may be expressed as an instruction set as a set of instructions.

The application program 1013 includes an application program that operates on the electronic device. That is, the application program 1013 may include instructions for an application driven by the processor 1022. The CSI-RS feedback determination program 1014 may generate CSI-RS feedback based on the relationship between the PDSCH precoder and the CSI-RS precoder according to embodiments of the present disclosure.

The peripheral device interface 1023 can control the connection between the input/output peripheral devices of the base station, the processor 1022, and the memory interface 1021. The processor 1022 controls the base station to provide the corresponding service using at least one software program. At this time, the processor 1022 may execute at least one program stored in the memory 1010 and provide a service corresponding to the program.

The input/output control unit 1040 may provide an interface between an input/output device such as the display unit 1050 and the input device 1060 and the peripheral device interface 1023. The display unit 1050 displays status information, input text, moving pictures, and still pictures. For example, the display unit 1050 may display application program information driven by the processor 1022.

The input device 1060 may provide input data generated by selecting an electronic device to the processor unit 1020 through the input/output control unit 1040. At this time, the input device 1060 may include a keypad including at least one hardware button and a touchpad that senses touch information. For example, the input device 1060 may provide touch information such as touch, touch movement, and touch release detected through the touch pad to the processor 1022 through the input/output control unit 1040. The electronic device 1000 may include a communication processing unit 1090 that performs communication functions for voice communication and data communication.

As above, exemplary embodiments are disclosed in the drawings and specifications. In this specification, embodiments have been described using specific terms, but this is only used for the purpose of explaining the technical idea of the present disclosure and is not used to limit the meaning or scope of the present disclosure as set forth in the patent claims. . Therefore, those skilled in the art will understand that various modifications and other equivalent embodiments are possible. Therefore, the true technical protection scope of the present disclosure should be determined by the technical spirit of the attached patent claims.

Claims (24)

Transmitting a sounding reference signal (SRS) to a base station;
Receiving a first reference signal to which a first precoder is applied from the base station;
Based on at least one of the relationship between the first precoder and a second precoder applied to the first physical downlink shared channel (PDSCH) by the base station based on the SRS and the channel estimated using the first reference signal generating feedback information including at least one of a rank indicator (RI) and a channel quality indicator (CQI);
Transmitting the generated feedback information to the base station; and
A method of operating a wireless communication device comprising receiving a second PDSCH to which at least one of the second precoder, the RI, and the CQI is applied. According to paragraph 1,
The first reference signal is,
A method of operating a wireless communication device, characterized in that at least one of a channel state information-reference signal (CSI-RS), a synchronization signal block (SSB), a demodulation-reference signal (DM-RS), and a tracking reference signal (TRS). According to paragraph 1,
The relationship between the first precoder and the second precoder is:
A method of operating a wireless communication device, comprising a gain ratio between a first beamforming gain of the first precoder and a second beamforming gain of the second precoder. According to paragraph 3,
A method of operating a wireless communication device, further comprising receiving a beamforming gain offset indicating the gain ratio from the base station. According to paragraph 3,
The step of generating the feedback information is,
measuring a first received power of the first PDSCH and a second received power of the first reference signal; and
A method of operating a wireless communication device, comprising calculating a ratio between the first received power and the second received power as the gain ratio. According to paragraph 1,
The relationship between the first precoder and the second precoder is,
Including identity between the first precoder and the second precoder,
The step of generating the feedback information is,
A method of operating a wireless communication device, further comprising checking whether the first precoder and the second precoder are the same. According to clause 6,
The step of checking whether the first precoder and the second precoder are the same,
measuring a first received power of the first PDSCH and a second received power of the first reference signal;
Comparing the measured first received power and the measured second received power; and
A method of operating a wireless communication device, comprising the step of determining whether the first precoder and the second precoder are the same based on the comparison result. According to clause 6,
The step of checking whether the first precoder and the second precoder are the same,
A method of operating a wireless communication device, comprising the step of determining whether the first precoder and the precoder are the same based on quasi-co-location (QCL) information received from the base station. According to clause 8,
The QCL information is,
A method of operating a wireless communication device, characterized in that it is defined as a type indicating that the first beamforming gain of the first precoder and the second beamforming gain of the second precoder are the same. According to clause 6,
The step of generating the feedback information is,
When the first precoder and the second precoder are different, requesting the base station to transmit a second reference signal to which the second precoder is applied;
Receiving the second reference signal from the base station; and
A method of operating a wireless communication device, comprising determining the feedback information based on a channel estimated using the second reference signal. Receiving a sounding reference signal (SRS) from a wireless communication device;
generating a second precoder based on the SRS;
Transmitting a first reference signal to which a first precoder is applied to the wireless communication device;
determining a precoding matrix indicator (PMI) candidate group based on the first precoder and the second precoder;
Receiving feedback information about the first reference signal including at least one of a rank indicator (RI) and a channel quality indicator (CQI); and
A method of operating a base station comprising transmitting a physical downlink shared channel (PDSCH) to which at least one of the first precoder, the RI, and the CQI is applied. According to clause 11,
The step of determining the PMI candidate group is,
A method of operating a base station, characterized in that one PMI is determined for each rank. According to clause 12,
The step of determining the PMI candidate group is,
A method of operating a base station, characterized by determining a PMI that minimizes the difference between the first precoder and the second precoder for each rank. According to clause 13,
The RI and the CQI are generated by the wireless communication device using the determined first PMI candidate group. A radio frequency integrated circuit (RFIC) that transmits a sounding reference signal (SRS) to a base station and receives a first reference signal to which a first precoder is applied from the base station; and
Based on at least one of the relationship between the first precoder and a second precoder applied to the first physical downlink shared channel (PDSCH) by the base station based on the SRS and the channel estimated using the first reference signal It includes a processor that generates feedback information including at least one of a rank indicator (RI) and a channel quality indicator (CQI),
The RFIC transmits the generated feedback information to the base station, and receives a second PDSCH to which at least one of the second precoder, the RI, and the CQI is applied. According to clause 15,
The first reference signal is,
A wireless communication device characterized by at least one of a channel state information-reference signal (CSI-RS), a synchronization signal block (SSB), a demodulation-reference signal (DM-RS), and a tracking reference signal (TRS). According to clause 15,
The relationship between the first precoder and the second precoder is:
A wireless communication device comprising a gain ratio between a first beamforming gain of the first precoder and a second beamforming gain of the second precoder. According to clause 17,
A wireless communication device, wherein the RFIC receives a beamforming gain offset indicating the gain ratio from the base station. According to clause 17,
The feedback information generation is,
The RFIC measures the first received power of the first PDSCH and the second received power of the first reference signal,
A wireless communication device comprising the step of calculating, by the processor, a ratio between the first received power and the second received power as the gain ratio. According to clause 15,
The relationship between the first precoder and the second precoder is,
Including identity between the first precoder and the second precoder,
To generate the feedback information,
The wireless communication device further comprising the step of the processor confirming whether the first precoder and the second precoder are the same. According to clause 20,
Checking whether the first precoder and the second precoder are the same,
The RFIC measures the first received power of the first PDSCH and the second received power of the first reference signal,
The processor compares the measured first received power and the measured second received power, and determines whether the first precoder and the second precoder are the same based on the comparison result. Wireless communication device. According to clause 20,
To check whether the first precoder and the second precoder are the same,
A wireless communication device, wherein the processor determines whether the first precoder and the precoder are the same based on quasi-co-location (QCL) information received from the base station. According to clause 22,
The QCL information is,
A wireless communication device, characterized in that it is defined as a type indicating that the first beamforming gain of the first precoder and the second beamforming gain of the second precoder are the same. According to clause 20,
To generate the feedback information,
When the first precoder and the second precoder are different from each other, the RFIC requests the base station to transmit a second reference signal to which the second precoder is applied, and receives the second reference signal from the base station. ,
A wireless communication device, wherein the processor determines the feedback information based on a channel estimated using the second reference signal.

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