Apparatus and method for wireless communication system

Abstract

A method performed in a wireless communication system according to one embodiment may comprise an operation of receiving a signal including demodulation reference signal (DMRS) symbols. The method may comprise an operation of estimating frequency domain channels corresponding to the DMRS symbols. The method may comprise an operation of estimating a frequency offset for each antenna group on the basis of a phase shift between the frequency domain channels and information on the antenna group. The method may comprise an operation of estimating a time domain channel on the basis of the frequency offset for each antenna group. The method may comprise an operation of estimating noise for each antenna group on the basis of the frequency domain channels, the information on the antenna group, and the frequency offset for each antenna group. The method may comprise an operation of acquiring a minimum mean squared error (MMSE) weight on the basis of the noise for each antenna group and the time domain channel. The method may comprise an operation of acquiring data by demodulating the signal on the basis of the MMSE weight.

Description

Device and method for wireless communication system

[0001] Embodiments of the present invention relate to a device and method for a wireless communication system.

[0002] Since the commercialization of the 4G (4th generation) communication system, the 5G (5th generation) communication system or 6G communication system is being developed to meet the continuously increasing demand for wireless data traffic.

[0003] To achieve high data rates, 5G communication systems are considering implementation in ultra-high frequency (mmWave) bands. 5G communication systems aim to utilize frequencies such as the 60 GHz band. To mitigate propagation path loss and increase radio transmission range in ultra-high frequency bands, 5G communication systems are applying beamforming, massive MIMO (massive MIMO), full-dimensional MIMO (FD-MIMO), array antennas, analog beamforming, and large-scale antenna technologies.

[0004] Additionally, to improve the network, technologies such as evolved small cells, advanced small cells, cloud radio access networks (cloud RAN), ultra-dense networks, device-to-device communication (D2D), wireless backhaul, moving networks, cooperative communication, coordinated multi-points (CoMP), and interference cancellation are being developed in 5G communication systems.

[0005] In 5G systems, advanced coding modulation (ACM) techniques such as hybrid frequency shift keying and quadrature amplitude modulation (FQAM) and sliding window superposition coding (SWSC), as well as advanced access technologies such as filter bank multi-carrier (FBMC), non-orthogonal multiple access (NOMA), and sparse code multiple access (SCMA), are being actively developed.

[0006] The above information may be provided as background art to aid in understanding the present disclosure. No claim or determination is made as to whether any of the above is applicable as prior art related to the present disclosure.

[0007] A method performed in a wireless communication system according to one embodiment may include receiving a signal including demodulation reference signal (DMRS) symbols. The method may include estimating frequency domain channels corresponding to the DMRS symbols. The method may include estimating a frequency offset for each antenna group based on a phase shift between the frequency domain channels and information about the antenna group. The method may include estimating a time domain channel based on the frequency offset for each antenna group. The method may include estimating noise for each antenna group based on the frequency domain channels, information about the antenna group, and the frequency offset for each antenna group. The method may include obtaining a minimum mean squared error (MMSE) weight based on the noise for each antenna group and the time domain channel. The method may include obtaining data by demodulating the signal based on the MMSE weight.

[0008] A base station according to one embodiment may include communication circuitry. The base station may include one or more processors operatively connected to the communication circuitry. The base station may include a memory storing instructions. The instructions, when individually or collectively executed by the one or more processors, may cause the base station to receive a signal including demodulation reference signal (DMRS) symbols. The instructions, when individually or collectively executed by the one or more processors, may cause the base station to estimate frequency domain channels corresponding to the DMRS symbols. The instructions, when individually or collectively executed by the one or more processors, may cause the base station to estimate a frequency offset for each antenna group based on a phase shift between the frequency domain channels and information about the antenna group. The instructions, when individually or collectively executed by the one or more processors, may cause the base station to estimate a time domain channel based on the frequency offset for each antenna group. The instructions, when individually or collectively executed by the one or more processors, may cause the base station to estimate noise for each antenna group based on the frequency domain channels, information about the antenna group, and the frequency offset for each antenna group. The instructions, when individually or collectively executed by the one or more processors, may cause the base station to obtain a minimum mean squared error (MMSE) weight based on the noise for each antenna group and the time domain channel.The above instructions, when individually or collectively executed by the one or more processors, may cause the base station to demodulate the signal based on the MMSE weights to obtain data.

[0009] FIG. 1 is a diagram for explaining a wireless communication system according to one embodiment.

[0010] FIG. 2 is a drawing for explaining a terminal and a base station according to one embodiment.

[0011] Figures 3a and 3b illustrate examples of wireless communication environments.

[0012] Figure 4 illustrates a block diagram of a device according to one embodiment.

[0013] Figures 5 and 6 illustrate a flowchart of an operating method of the device according to one embodiment.

[0014] Hereinafter, embodiments will be described in detail with reference to the attached drawings. In the description with reference to the attached drawings, identical components are assigned the same reference numerals regardless of the drawing numbers, and redundant descriptions thereof will be omitted.

[0015]

[0016] In the following description, terms related to time resources (e.g., symbol, slot, subframe, radio frame), terms related to frequency resources (e.g., resource element (RE), resource block (RB), bandwidth part (BWP), bandwidth (BW), carrier), terms related to signals (e.g., RS, symbol, information), terms related to signal processing (e.g., encoding / decoding, channel coding, scrambling, modulation, IFFT / FFT, cyclic prefix (CP) insertion / deletion)) are described based on terms defined in the current 3GPP LTE or NR standards, but other terms with equivalent technical meanings may be used. In addition, terms referring to parameters (e.g., format name, parameter name), terms indicating variables (e.g., c, f, i, j, etc.), and terms referring to network entities (e.g., transmission device, reception device, transmitter) are used. (Transmission end), reception end, base station, terminal, communication node, radio node, radio unit, network node, master node (MN), secondary node (SN), transmission / reception point (TRP), digital unit (DU), radio unit (RU), massive MIMO unit (MMU), etc. are examples for convenience of explanation. Therefore, the present disclosure is not limited to the terms described below, and other terms having equivalent technical meanings may be used.

[0017] In addition, the present disclosure describes various embodiments using terms used in some communication standards (e.g., LTE (long term evolution) and NR (new radio) defined by the 3rd Generation Partnership Project (3GPP)). The 3GPP mobile communication system covered herein may include both the 4th generation (4G, hereinafter referred to as LTE (Long Term Evolution)) and the 5th generation (5G, hereinafter referred to as NR (New Radio)). However, the embodiments of the present disclosure can be easily modified and applied not only to the 3GPP mobile communication system but also to other communication systems. Although the transmission or reception operation according to the embodiments of the present disclosure is described as an example of uplink transmission, the same or similar technical principles can be applied to downlink transmission or sidelink transmission.

[0018]

[0019] FIG. 1 is a diagram for explaining a wireless communication system according to one embodiment.

[0020] Referring to FIG. 1, according to one embodiment, a base station (110) and a terminal (120) can be identified as part of nodes utilizing a wireless channel in a wireless communication system (100). The terminal (120) may be connected to multiple base stations rather than just one base station (110) (e.g., see FIGS. 3A and 3B). Although not illustrated in FIG. 1, the base stations may also be connected to the terminal (120) via multiple connectivity (e.g., dual connectivity (DC)).

[0021] According to one embodiment, the base station (110) may be a network infrastructure that provides wireless access to the terminal (120). The base station (110) may have coverage (e.g., a geographical area) defined based on the transmission distance of a signal. Hereinafter, the term "coverage" may refer to a service coverage area that the base station (110) can service. The base station (110) may cover one cell or multiple cells. Here, the multiple cells may be distinguished by the frequency they support and / or the sectors they cover.

[0022] According to one embodiment, the base station (110) may be referred to as an access point (AP), an eNodeB (eNB), a 5th generation node, a 5G NodeB (NB), a next generation node B (gNB), a wireless point, a transmission / reception point (TRP), a distributed unit (DU), a radio unit (RU), a remote radio head (RRH), or other terms having equivalent technical meanings thereto, in addition to a base station. The base station (110) may be connected to one or more transmission / reception points (TRPs). The base station (110) may transmit a downlink signal to a terminal (120) or receive an uplink signal from the terminal (120) through one or more TRPs.

[0023] According to one embodiment, the terminal (120) is a device used by a user and can communicate with the base station (110) via a wireless channel. In some cases, the terminal (120) can be operated without the involvement of the user. At least one of the terminals (120) is a device that performs machine type communication (MTC) and may not be carried by the user. The terminal (120) may be referred to as a terminal, user equipment (UE), mobile station, subscriber station, customer premises equipment (CPE), remote terminal, wireless terminal, electronic device, vehicle terminal, user device, or other terms having equivalent technical meanings.

[0024]

[0025] FIG. 2 is a drawing for explaining a terminal and a base station according to one embodiment.

[0026] Referring to FIG. 2, according to one embodiment, a base station (110) may include a communication circuit (111), a memory (112), and one or more processors (113).

[0027] According to one embodiment, the communication circuit (111) may perform functions for transmitting and receiving signals via a wireless channel. For example, the communication circuit (111) may perform conversion between baseband signals and bit streams according to the physical layer specifications of the system. For example, when transmitting data, the communication circuit (111) may generate complex symbols by encoding and modulating the transmitted bit stream. For example, when receiving data, the communication circuit (111) may restore the received bit stream by demodulating and decoding the baseband signal. The communication circuit (111) may be configured to perform at least one of the operations of the transmitter or the receiver described with reference to FIGS. 4 to 6 .

[0028] According to one embodiment, the communication circuit (111) may upconvert a baseband signal into an RF (radio frequency) band signal and transmit it through an antenna, and downconvert an RF band signal received through the antenna into a baseband signal. To this end, the communication circuit (111) may include a transmit filter, a receive filter, an amplifier, a mixer, an oscillator, a digital to analog convertor (DAC), and / or an analog to digital convertor (ADC). The communication circuit (111) may include a plurality of transmit and receive paths. The communication circuit (111) may include at least one antenna array composed of a plurality of antenna elements. In terms of hardware, the communication circuit (111) may be composed of a digital unit and an analog unit, and the analog unit may be composed of a plurality of sub-units depending on operating power and / or operating frequency. The communication circuit (111) may include a unit that forms a beam (e.g., a beamforming unit).

[0029] According to one embodiment, the communication circuit (111) can transmit and receive signals. For this purpose, the communication circuit (111) can include at least one transceiver. For example, the communication circuit (111) can transmit a synchronization signal, a reference signal, system information, messages, control information, and / or data. The communication circuit (111) can perform beamforming. The communication circuit (111) can apply beamforming weights to signals to be transmitted and received to impart directionality to the signals. The communication circuit (111) can generate baseband signals. An RF unit within the communication circuit (111) can transmit the generated signals through an antenna.

[0030] According to one embodiment, the communication circuit (111) can transmit and receive signals as described above. Accordingly, all or part of the communication circuit (111) may be referred to as a transmitter, a receiver, or a transceiver. Furthermore, the transmission and reception performed via a wireless channel in the following description may be processed as described above by the communication circuit (111).

[0031] According to one embodiment, the memory (112) can store data such as basic programs, application programs, and setting information for the operation of the base station (110). The memory (112) may be referred to as a storage unit. The memory (112) may be composed of volatile memory, non-volatile memory, or a combination of volatile memory and non-volatile memory. The memory (112) can provide stored data upon request from the processor (113).

[0032] According to one embodiment, the processor (113) may be implemented as a circuit (e.g., a processing circuit) such as a system on chip (SoC) or an integrated circuit (IC). The processor (113) may include one or more processors. For example, the processor (113) may include a combination of one or more processors such as a CPU, a GPU, an MPU, an AP, and a CP.

[0033] According to one embodiment, the memory (112) may include one or more memories. The instructions stored in the memory (112) may be stored in a single memory. The instructions stored in the memory (112) may be divided and stored in a plurality of memories. The instructions stored in the memory (112) may be individually or collectively executed by the processor (113) to cause the base station (110) to perform and / or control the method described with reference to FIGS. 1 to 6. The instructions stored in the memory (112) may be individually or collectively executed by a plurality of processors to cause the base station (110) to perform and / or control the method described with reference to FIGS. 1 to 6.

[0034] According to one embodiment, the processor (113) can control the overall operations of the base station (110). The processor (113) may be referred to as a control unit. The processor (113) can transmit and receive signals through the communication circuit (111). The processor (113) can record data in the memory (112) and read data recorded in the memory (112). The processor (113) can perform functions of a protocol stack required by a communication standard. The processor (113) can control the base station (110) to perform operations.

[0035] The configuration of the base station (110) illustrated in FIG. 2 is merely an example of a base station, and examples of base stations performing embodiments of the present disclosure are not limited to the configuration illustrated in FIG. 2. That is, depending on the embodiments, some configurations may be added, deleted, or changed.

[0036] Referring to FIG. 2, according to one embodiment, the terminal (120) may include a communication circuit (121), a memory (122), and one or more processors (123).

[0037] According to one embodiment, the communication circuit (121) may perform functions for transmitting and receiving signals via a wireless channel. The communication circuit (121) may perform conversion between a baseband signal and a bit stream according to the physical layer specifications of the system. For example, when transmitting data, the communication circuit (121) may generate complex symbols by encoding and modulating a transmission bit stream. For example, when receiving data, the communication circuit (121) may restore a reception bit stream by demodulating and decoding a baseband signal. The communication circuit (121) may upconvert a baseband signal to an RF band signal and transmit the upconverted signal through an antenna, and downconvert an RF band signal received through the antenna to a baseband signal. The communication circuit (121) may include a transmit filter, a receive filter, an amplifier, a mixer, an oscillator, a DAC, and / or an ADC.

[0038] According to one embodiment, the communication circuit (121) may include a plurality of transmit / receive paths. Furthermore, the communication circuit (121) may include an antenna unit. The communication circuit (121) may include at least one antenna array composed of a plurality of antenna elements. In terms of hardware, the communication circuit (121) may be composed of a digital circuit and an analog circuit (e.g., a radio frequency integrated circuit (RFIC)). Here, the digital circuit and the analog circuit may be implemented in one package. In addition, the communication circuit (121) may include a plurality of RF chains. The communication circuit (121) may perform beamforming. The communication circuit (121) may apply beamforming weights to signals to be transmitted and received.

[0039] According to one embodiment, the communication circuit (121) can transmit and receive signals. For this purpose, the communication circuit (121) can include at least one transceiver. The communication circuit (121) can receive a downlink signal. The downlink signal can include a synchronization signal (SS), a reference signal (RS) (e.g., a cell-specific reference signal (CRS), a demodulation (DM)-RS), system information (e.g., a MIB, a SIB, remaining system information (RMSI), other system information (OSI)), a configuration message, control information, and / or downlink data. The communication circuit (121) can transmit an uplink signal. The uplink signal may include uplink control information (UCI), random access related signals (e.g., random access preamble (RAP) (or Msg1 (message 1)), Msg3 (message 3)), reference signals (e.g., sounding reference signal (SRS), DM-RS), and / or buffer status report (BSR). The uplink control information may include scheduling request (SR), ACK / NACK information of a hybrid acknowledge (HARQ) procedure, and / or channel state information (CSI).

[0040] According to one embodiment, the communication circuit (121) may transmit an uplink demodulation reference signal (DMRS) symbol. The communication circuit (121) may include an RF processing unit and a baseband processing unit. The RF processing unit may perform functions for transmitting and receiving signals through a wireless channel, such as signal band conversion and amplification. That is, the RF processing unit may upconvert a baseband signal provided from the baseband processing unit into an RF band signal and transmit the same through an antenna, and downconvert an RF band signal received through the antenna into a baseband signal. The terminal (120) may include one or more antennas, and the RF processing unit may include a plurality of RF chains. The RF processing unit may perform beamforming. For beamforming, the RF processing unit may adjust the phase and magnitude of each of the signals transmitted and received through a plurality of antennas or antenna elements.

[0041] According to one embodiment, the baseband processing unit can perform conversion between baseband signals and bit streams according to the physical layer specifications of the system. For example, when transmitting data, the baseband processing unit can generate complex symbols by encoding and modulating the transmission bit stream. For example, when transmitting data according to the orthogonal frequency division multiplexing (OFDM) method, the baseband processing unit can generate complex symbols by encoding and modulating the transmission bit stream, map the complex symbols to subcarriers, and then configure OFDM symbols through an inverse fast Fourier transform (IFFT) operation and cyclic prefix (CP) insertion. For example, when receiving data, the baseband processing unit can restore the received bit stream by demodulating and decoding the baseband signal provided from the RF processing unit. For example, when receiving data according to the OFDM method, the baseband processing unit divides the baseband signal provided from the RF processing unit into OFDM symbol units, restores signals mapped to subcarriers through an FFT (fast Fourier transform) operation, and then restores the received bit string through demodulation and decoding.

[0042] According to one embodiment, the communication circuit (121) can transmit and receive signals as described above. Accordingly, all or part of the communication circuit (121) may be referred to as a transmitter, a receiver, or a transceiver. The communication circuit (121) may include a plurality of communication modules to support a plurality of different wireless access technologies and / or to process signals of different frequency bands. For example, the different wireless access technologies may include wireless LAN (e.g., IEEE 802.1x) and / or cellular networks (e.g., LTE, NR). For example, the different frequency bands may include a super high frequency (SHF) (e.g., 2.5 GHz, 5 GHz) band, a millimeter wave (mmWave) (e.g., 60 GHz) band.

[0043] According to one embodiment, the memory (122) may store data such as basic programs, application programs, and / or setting information for the operation of the terminal (120). The memory (122) may be referred to as a storage unit. The memory (122) may be composed of volatile memory, non-volatile memory, or a combination of volatile memory and non-volatile memory.

[0044] According to one embodiment, the processor (123) may be implemented as a circuit (e.g., a processing circuit) such as a system on chip (SoC) or an integrated circuit (IC). The processor (123) may include one or more processors. For example, the processor (123) may include a combination of one or more processors such as a CPU, a GPU, an MPU, an AP, and a CP.

[0045] According to one embodiment, the memory (122) may include one or more memories. The instructions stored in the memory (122) may be stored in a single memory. The instructions stored in the memory (122) may be divided and stored in multiple memories. The instructions stored in the memory (122) may be individually or collectively executed by the processor (123) to cause the terminal (120) to perform and / or control the method described with reference to FIGS. 1 to 6. The instructions stored in the memory (122) may be individually or collectively executed by multiple processors to cause the terminal (120) to perform and / or control the method described with reference to FIGS. 1 to 6.

[0046] According to one embodiment, the processor (123) can control the overall operations of the terminal (120). The processor (123) may be referred to as a control unit. The processor (123) can transmit and receive signals through the communication circuit (121). The processor (123) can record data in the memory (122) and read data recorded in the memory (122). The processor (123) may include various modules for performing communication. The processor (123) may perform functions of a protocol stack required by a communication standard. For this purpose, the processor (123) may include at least one processor or microprocessor. The processor (123) may include a communication processor (CP) for performing control for communication and / or an application processor (AP) for performing control of an upper layer (e.g., an application program). The processor (123) may control the terminal (120) to perform operations.

[0047]

[0048] Figures 3a and 3b illustrate examples of wireless communication environments.

[0049] Although the base station (e.g., 110) is described as a single entity in FIG. 2, the present disclosure is not limited thereto. Referring to FIGS. 3A and 3B, the base stations (e.g., 110-1 to 110-8) may be implemented to form an access network with a distributed deployment.

[0050] Referring to FIGS. 3A and 3B, within a cell composed of distributed base stations (e.g., 110-1 to 110-4 or 110-5 to 110-8), a terminal (120) can move at high speed. Each of the base stations (e.g., 110-1 to 110-8) receives an uplink signal transmitted by the terminal (120). can be estimated. N rx N through the dog antenna layer Uplink signal transmitted in a communication system utilizing the signal can be expressed as in mathematical expression 1.

[0051] [Mathematical Formula 1]

[0052]

[0053] In mathematical equation 1, is the signal received through the kth tone and lth symbol (e.g., the signal received by the base station), is (N rx x 1) can be a vector of size . is the signal transmitted through the kth tone and lth symbol (e.g., the signal transmitted by the terminal), is (N layer x 1) can be a vector of size . is for the kth tone, lth symbol (N rx x N layer ) can be a channel matrix of size . is the noise and interference received through the kth tone and lth symbol (N rx x 1) can be a vector of size .

[0054] Each of the base stations (e.g., 110-1 to 110-8) can calculate the MMSE weight W through minimum mean squared error (MMSE) estimation and perform equalization through mathematical expression 2 including W.

[0055] [Equation 2]

[0056]

[0057] In mathematical expression 2, is the kth tone, estimated from the lth symbol (N rx x N layer ) can be a channel matrix of size . is for noise and interference (N rx x N rx ) can be a covariance matrix of size .

[0058] To calculate the MMSE weight W, (N rx x N rx ) requires an inversion operation on a matrix of size N, and this inversion operation depends on the number of antennas (e.g. N rx ) increases, the complexity can also increase significantly. To reduce the computational complexity, equalization can be performed using Equation 3 (e.g., whitening + MMSE).

[0059] [Equation 3]

[0060]

[0061] In mathematical expression 3, I is (N layer x N layer ) can be an identity matrix of size . It is used in mathematical expression 3. is measured in a specific resource area. can be obtained using .

[0062] In developing 5G communication systems, as well as 4G, efforts have been made to support communication even in high-speed mobile environments of terminals (120). However, in OFDM systems, as the mobile speed of the terminal (120) increases, the frequency offset increases, and the increased frequency offset can degrade link performance.

[0063]

[0064] FIG. 4 illustrates a block diagram of a device according to one embodiment, and FIGS. 5 and 6 illustrate flowcharts of a method of operating the device according to one embodiment.

[0065] According to one embodiment, a base station (e.g., base station (110) of FIG. 1) can perform frequency offset estimation and noise estimation to alleviate performance degradation issues occurring in a high-speed mobile environment of a terminal (e.g., terminal (120) of FIG. 1). The base station (110) can perform frequency offset estimation and noise estimation for each antenna group. The base station (110) can increase the estimation accuracy of the frequency offset and reduce the complexity of the noise estimation operation.

[0066] Referring to FIG. 4, according to one embodiment, the base station (110) transmits a demodulation reference signal (DMRS) symbol Y rs and data symbol Y data The base station (110) can receive a signal Y including the DMRS symbol Y rs Data symbol Y based on dataData can be acquired by demodulating (e.g., equalizing). Modules utilized for data acquisition of the base station (110) (e.g., frequency domain channel estimation module (410), frequency offset estimation module (420), time domain channel estimation module (430), noise estimation module (440), and MMSE weight acquisition module (450), and / or demodulation module (460)) may be modules implemented in a communication circuit (e.g., communication circuit (111) of FIG. 2) (e.g., transceiver) or a processor (e.g., processor (113) of FIG. 2) (e.g., control unit).

[0067] Referring to FIG. 5, according to one embodiment, operations 510 to 570 may be performed sequentially, but are not necessarily performed sequentially. For example, the order of each operation (510 to 570) may be changed, and at least two operations may be performed in parallel.

[0068] According to one embodiment, operations 510 to 570 may be understood to be performed in the communication circuit (111) and / or processor (113) of the base station (110).

[0069] In operation 510, a base station (110) according to one embodiment transmits a DMRS symbol Y rs A signal Y including a DMRS symbol Y can be received. The signal Y may be an uplink signal transmitted by a terminal (e.g., terminal (120) of FIG. 1). The signal Y may be a DMRS symbol Y. rs and data symbol Y data may include.

[0070] In operation 520, a frequency domain channel estimation module (410) according to one embodiment can estimate frequency domain channels corresponding to DMRS symbols.

[0071] In operation 530, the frequency offset estimation module (420) according to one embodiment may estimate a frequency offset for each antenna group based on the phase shift between frequency domain channels and information about the antenna group. Frequency offset for each antenna group can be estimated through mathematical formula 4.

[0072] [Equation 4]

[0073]

[0074] In mathematical equation 4, may be a frequency domain channel value estimated from the index r of the antenna, the DMRS port p, the index l of the DMRS symbol pair, the index l(1) of the second symbol of the lth DMRS symbol pair, and the index k of the RE (resource element). may be a conjugate complex number of a frequency domain channel value estimated from the index r of the antenna, the DMRS port p, the index l of the DMRS symbol pair, the index l(0) of the first symbol of the lth DMRS symbol pair, and the index k of the RE (resource element). silver is the position of the first symbol of the th DMRS symbol pair, silver It may be the location of the second symbol of the second DMRS symbol pair.

[0075] In one embodiment, the index r of an antenna may be the index of all antennas included in an antenna group. That is, the frequency offset for each antenna group may be estimated based on the phase shift between frequency domain channels calculated for each antenna. The index k of an RE may be the index of all REs included in an allocated resource block (RB), or may be the index of a sparse RE. The index l of a DMRS symbol pair may be defined based on the DMRS symbol allocated to a terminal (e.g., 120). For example, if the number of allocated DMRS symbols is 4 (e.g., if the indices of the allocated DMRS symbols are 0, 1, 2, 3), 6 (e.g., 4C2) DMRS symbol pairs can be defined (e.g., pair 0: (0,1), pair 1: (0,2), pair 2: (0,3), pair 3: (1,2), pair 4: (1, 3), pair 5: (2,3)). As the number of allocated DMRS symbols increases, the number of definable DMRS symbol pairs can also increase. If the number of allocated DMRS symbols is sufficiently large, instead of calculating frequency offsets for all definable DMRS symbol pairs, only a few DMRS symbol pairs can be selectively utilized. That is, the frequency offset estimation module (420) can select and / or sum the phase shifts calculated for each antenna and divide them by DMRS symbol interval (e.g., the position difference between symbols included in a DMRS symbol pair).

[0076] According to one embodiment, as described above, information about an antenna group may include indices of antennas constituting each antenna group. Information about an antenna group may include a signal (e.g., DMRS symbol Y rs and data symbol Y data It may be obtained based on the antenna-specific frequency offset that is stored prior to reception of signal Y or estimated after reception of signal Y.

[0077] According to one embodiment, antenna grouping is performed on a signal (e.g., DMRS symbol Y rs and data symbol Y data It may be performed before receiving the signal Y including the antenna. For example, if there are 8 antennas, 4 antenna groups can be set (e.g., 8 / 4=2 antennas are assigned to each group). After antenna grouping, information about the antenna groups can be stored in a memory (e.g., memory (112) of FIG. 2). Information about the antenna groups can be utilized later when estimating the frequency offset for each antenna group.

[0078] According to one embodiment, antenna grouping is performed on a signal (e.g., DMRS symbol Y rs and data symbol Y data may be performed after reception of a signal Y) including antenna grouping. Antenna grouping may be performed based on an antenna-specific frequency offset estimated after reception of the signal. Antenna-specific frequency offset can be estimated through mathematical formula 5.

[0079] [Equation 5]

[0080]

[0081] Frequency offset for each antenna with reference to Equations 4 and 5 and frequency offset by antenna group When comparing the frequency offset per antenna, can be calculated for a single antenna (e.g., antenna index r).

[0082] According to one embodiment, the base station (110) can first estimate the frequency offset for each antenna after receiving the signal. For example, if there are eight antennas, the frequency offset for each of the eight antennas This can be obtained (e.g. However, the size of the frequency offset is (defined within) The base station (110) is configured to estimate the frequency offset per antenna Antennas can be grouped based on .

[0083] According to one embodiment, the base station (110) can group antennas based on the size of the frequency offset per antenna (e.g.,

[0084] According to one embodiment, the base station (110) can group antennas based on the sign of the frequency offset per antenna (e.g., ,

[0085] According to one embodiment, the base station (110) may group antennas based on a K-means clustering algorithm that utilizes the size of the frequency offset for each antenna. The K-means clustering algorithm may be an algorithm used to group data into k (e.g., k=4) groups (or clusters).

[0086] According to one embodiment, the base station (110) may first group antennas (e.g., form clusters) (e.g., assign antennas to clusters) based on the magnitude of the frequency offset for each antenna. The base station (110) may set the average of the frequency offsets of the antennas assigned to the cluster as the initial center (start centroids) of the cluster. The initial center (start centroids) of the cluster may be expressed using mathematical expression 6.

[0087] [Equation 6]

[0088]

[0089] The base station (110) can reassign antennas to clusters closest to the initial center. The distance (e.g., degree of proximity) between the initial center and the frequency offset can be calculated in the angular domain. The base station (110) can update the center of the cluster by averaging the frequency offsets of the antennas reassigned to the cluster. The base station (110) can reassign antennas to clusters closest to the updated center.

[0090] In one embodiment, the base station (110) may repeat center update and clustering. The base station (110) may stop center update and clustering if the antennas forming the cluster remain the same. The base station (110) may merge adjacent clusters into a single cluster if the difference between the centers of adjacent clusters is less than or equal to a threshold (e.g., 10 degrees). Antennas for which clustering has been completed may each form an antenna group. After antenna grouping, information about the antenna group may be stored in a memory (e.g., the memory (112) of FIG. 2). Information about the antenna group may be utilized when estimating a frequency offset for each antenna group.

[0091] In operation 540, a time domain estimation module (430) according to one embodiment can estimate a time domain channel based on a frequency offset per antenna group.

[0092] In operation 550, a noise estimation module (440) according to one embodiment can estimate noise for each antenna group based on frequency domain channels, information about antenna groups, and frequency offsets for each antenna group.

[0093] According to one embodiment, the noise estimation module (440) generates a covariance matrix for noise for each antenna group based on information about the antenna group. can be estimated. The noise estimation module (440) calculates the covariance matrix based on the frequency offset for each antenna group. can be updated. The noise estimation module (440) calculates the entire covariance matrix based on the updated covariance matrix. can be obtained. Covariance matrix for each antenna group and the entire covariance matrix can be expressed through mathematical formula 7.

[0094] [Equation 7]

[0095]

[0096] In mathematical expression 7, the number of antenna groups is For individuals, the entire covariance matrix The diagonal elements of the covariance matrix for each antenna group (where i is the index of the antenna group) can correspond to the covariance matrix for each antenna group. silver ( x ) can be a matrix of size (however, is the number of antennas constituting antenna group i).

[0097] According to one embodiment, the noise estimation module (440) calculates a covariance matrix The update of the covariance matrix can be performed optionally. The update of (e.g., covariance reconstruction) can be significant in the high signal to noise ratio (SNR) region. The noise estimation module (440) calculates the covariance matrix Covariance matrix to determine whether to update The DMRS (demodulation reference signal) SNR (signal to noise ratio) can be utilized.

[0098] Referring to FIG. 6, according to one embodiment, in operation 610, the noise estimation module (440) calculates a covariance matrix The average DMRS SNR can be obtained.

[0099] According to one embodiment, in operation 620, the noise estimation module (440) estimates the average DMRS SNR (e.g., DMRS_SNR AVG ) and threshold (e.g. DMRS_SNR TH ) can be compared.

[0100] According to one embodiment, in operation 630, the noise estimation module (440) determines whether the average DMRS SNR is greater than a threshold (e.g., DMRS_SNR TH ) is greater than or equal to the covariance matrix, the covariance matrix can be updated based on the frequency offset per antenna group. If the average DMRS SNR is greater than or equal to the threshold (e.g. DMRS_SNR TH ) may not be updated.

[0101] According to one embodiment, the entire covariance matrix is ​​updated and / or the covariance matrix is ​​not updated based on the operation 640. can be obtained. Below, we will explain in detail how to update the covariance matrix.

[0102] According to one embodiment, as described above, the noise estimation module (440) calculates a frequency offset for each antenna group. Covariance matrix for each antenna group based on can be updated.

[0103] According to one embodiment, the noise estimation module (440) calculates a covariance matrix for each antenna group using mathematical expression 8. can be updated. The updated covariance matrix is can be expressed as

[0104] [Equation 8]

[0105]

[0106] Referring to mathematical expression 8, the noise estimation module (440) calculates the absolute value of the frequency offset for each antenna group. This threshold If it is larger, the covariance matrix Off-diagonal elements of the signal can be replaced with 0. In addition, the noise estimation module (440) calculates the absolute value of the frequency offset for each antenna group. This threshold If less than or equal to , the covariance matrix can be maintained as is.

[0107] According to one embodiment, the noise estimation module (440) calculates a covariance matrix for each antenna group using mathematical expression 9. can also be updated. Similarly, the updated covariance matrix is can be expressed as a noise estimation module (440) with a diagonal loading factor Covariance matrix based on can be corrected.

[0108] [Equation 9]

[0109]

[0110]

[0111]

[0112] Referring to mathematical expression 9, the diagonal load variable is the absolute value of the frequency offset per antenna group. This first threshold If it is less than or equal to , it can be set to 0. Diagonal load variable is the absolute value of the frequency offset per antenna group. This second threshold If it is greater than or equal to , it can be set to 1. Diagonal load variable is the absolute value of the frequency offset per antenna group. This first threshold and the second threshold If the value is between , the first threshold , second threshold , and absolute value can be set based on.

[0113] According to one embodiment, the noise estimation module (440) calculates a covariance matrix for each antenna group using mathematical expression 10. can also be updated. The updated covariance matrix is , and the noise estimation module (440) is a diagonal load variable Covariance matrix based on can be corrected.

[0114] [Equation 10]

[0115]

[0116]

[0117] Referring to Equation 10, the diagonal load variable is is the absolute value of the frequency offset per antenna group. can be set based on a table containing different diagonal load variables according to the threshold values ​​included in Equations 8 to 10 (e.g., ) may be experimentally obtained values ​​and may vary depending on the number of antennas included in the antenna group.

[0118] Referring again to FIG. 5, in operation 560, the MMSE (minimum mean squared error) weight acquisition module (450) according to one embodiment can acquire MMSE weights based on noise and time domain channels for each antenna group.

[0119] In operation 570, a demodulation module (460) according to one embodiment generates a signal (e.g., data symbol Y) based on MMSE weights. data ) can be used to obtain data by demodulating (e.g. equalizing).

[0120] According to one embodiment, the base station (110) can perform frequency offset estimation and noise estimation to alleviate performance degradation issues occurring in a high-speed mobile environment of the terminal (120). The base station (110) can perform frequency offset estimation and noise estimation for each antenna group. The base station (110) can increase the accuracy of frequency offset estimation and reduce the complexity of the noise estimation operation. Although the present disclosure describes the base station (110) performing the estimation, it should be noted that the terminal (120) can also perform the estimation.

[0121]

[0122] A method performed in a wireless communication system according to one embodiment may include receiving a signal including demodulation reference signal (DMRS) symbols. The method may include estimating frequency domain channels corresponding to the DMRS symbols. The method may include estimating a frequency offset for each antenna group based on a phase shift between the frequency domain channels and information about the antenna group. The method may include estimating a time domain channel based on the frequency offset for each antenna group. The method may include estimating noise for each antenna group based on the frequency domain channels, information about the antenna group, and the frequency offset for each antenna group. The method may include obtaining a minimum mean squared error (MMSE) weight based on the noise for each antenna group and the time domain channel. The method may include obtaining data by demodulating the signal based on the MMSE weight.

[0123] According to one embodiment, the information about the antenna group may include indices of the antennas constituting each antenna group. The frequency offset for each antenna group may be estimated based on a phase shift between the frequency domain channels calculated for each of the antennas.

[0124] The information about the antenna group may be stored before receiving the signal or may be acquired based on an estimated frequency offset for each antenna after receiving the signal. The information about the antenna group acquired after receiving the signal may be acquired by grouping antennas based on the size of the frequency offset for each antenna, by grouping antennas based on the sign of the frequency offset for each antenna, or by grouping antennas based on a K-means clustering algorithm using the size of the frequency offset for each antenna.

[0125] According to one embodiment, the operation of estimating noise for each antenna group may include an operation of estimating a covariance matrix for noise for each antenna group based on information about the antenna group. The operation of estimating noise for each antenna group may include an operation of updating the covariance matrix based on a frequency offset for each antenna group. The operation of estimating noise for each antenna group may include an operation of obtaining an entire covariance matrix based on the updated covariance matrix.

[0126] According to one embodiment, the operation of updating the covariance matrix may include the operation of obtaining an average demodulation reference signal (DMRS) signal to noise ratio (SNR) of the covariance matrix. The operation of updating the covariance matrix may include the operation of comparing the average DMRS SNR with a threshold. The operation of updating the covariance matrix may include the operation of updating the covariance matrix based on a frequency offset for each antenna group when the average DMRS SNR is greater than or equal to the threshold.

[0127] According to one embodiment, the operation of updating the covariance matrix may include an operation of replacing off-diagonal elements of the covariance matrix with 0 when the absolute value of the frequency offset for each antenna group is greater than a threshold value. The operation of updating the covariance matrix may include an operation of maintaining the covariance matrix when the absolute value of the frequency offset for each antenna group is less than or equal to the threshold value.

[0128] In one embodiment, the operation of updating the covariance matrix may include an operation of correcting the covariance matrix based on a diagonal loading factor. The diagonal loading factor may be set to a value corresponding to a frequency offset for each antenna group.

[0129] According to one embodiment, the diagonal load variable may be set to 0 when the absolute value of the frequency offset for each antenna group is less than or equal to a first threshold value. The diagonal load variable may be set to 1 when the absolute value is greater than or equal to a second threshold value. The diagonal load variable may be set based on the first threshold value, the second threshold value, and the absolute value when the absolute value is a value between the first threshold value and the second threshold value.

[0130] According to one embodiment, the diagonal load variables may be set based on a table including different diagonal load variables according to the absolute values.

[0131] A base station according to one embodiment may include communication circuitry. The base station may include one or more processors operatively connected to the communication circuitry. The base station may include a memory storing instructions. The instructions, when individually or collectively executed by the one or more processors, may cause the base station to receive a signal including demodulation reference signal (DMRS) symbols. The instructions, when individually or collectively executed by the one or more processors, may cause the base station to estimate frequency domain channels corresponding to the DMRS symbols. The instructions, when individually or collectively executed by the one or more processors, may cause the base station to estimate a frequency offset for each antenna group based on a phase shift between the frequency domain channels and information about the antenna group. The instructions, when individually or collectively executed by the one or more processors, may cause the base station to estimate a time domain channel based on the frequency offset for each antenna group. The instructions, when individually or collectively executed by the one or more processors, may cause the base station to estimate noise for each antenna group based on the frequency domain channels, information about the antenna group, and the frequency offset for each antenna group. The instructions, when individually or collectively executed by the one or more processors, may cause the base station to obtain a minimum mean squared error (MMSE) weight based on the noise for each antenna group and the time domain channel.The above instructions, when individually or collectively executed by the one or more processors, may cause the base station to demodulate the signal based on the MMSE weights to obtain data.

[0132] According to one embodiment, the information about the antenna group may include indices of the antennas constituting each antenna group. The frequency offset for each antenna group may be estimated based on a phase shift between the frequency domain channels calculated for each of the antennas.

[0133] According to one embodiment, the information about the antenna group may be obtained based on a frequency offset per antenna that is stored before reception of the signal or estimated after reception of the signal. The information about the antenna group obtained after reception of the signal may be obtained by grouping antennas based on a magnitude of the frequency offset per antenna, by grouping antennas based on a sign of the frequency offset per antenna, or by grouping antennas based on a K-means clustering algorithm that utilizes the magnitude of the frequency offset per antenna.

[0134] In one embodiment, the instructions, when individually or collectively executed by the one or more processors, may cause the base station to estimate a covariance matrix for noise for each antenna group based on information about the antenna group. The processor may cause the base station to update the covariance matrix based on a frequency offset for each antenna group. The processor may cause the base station to obtain a full covariance matrix based on the updated covariance matrix.

[0135] In one embodiment, the instructions, when individually or collectively executed by the one or more processors, may cause the base station to obtain an average demodulation reference signal (DMRS) signal-to-noise ratio (SNR) of the covariance matrix. The processor may cause the base station to compare the average DMRS SNR with a threshold. The processor may cause the base station to update the covariance matrix based on the frequency offset for each antenna group if the average DMRS SNR is greater than or equal to the threshold.

[0136] In one embodiment, the instructions, when individually or collectively executed by the one or more processors, may cause the base station to replace off-diagonal elements of the covariance matrix with 0 if the absolute value of the frequency offset per antenna group is greater than a threshold value. The processor may cause the base station to maintain the covariance matrix if the absolute value of the frequency offset per antenna group is less than or equal to the threshold value.

[0137] In one embodiment, the instructions, when individually or collectively executed by the one or more processors, cause the base station to, in one embodiment, cause the processors to cause the base station to correct the covariance matrix based on a diagonal loading factor. The diagonal loading factor may be set to a value corresponding to a frequency offset for each antenna group.

[0138] According to one embodiment, the diagonal load variable may be set to 0 when the absolute value of the frequency offset for each antenna group is less than or equal to a first threshold value. The diagonal load variable may be set to 1 when the absolute value is greater than or equal to a second threshold value. The diagonal load variable may be set based on the first threshold value, the second threshold value, and the absolute value when the absolute value is a value between the first threshold value and the second threshold value.

[0139] According to one embodiment, the diagonal load variables may be set based on a table including different diagonal load variables according to the absolute values.

[0140] According to one embodiment, the diagonal elements of the entire covariance matrix may correspond to covariance matrices for each antenna group.

[0141]

[0142] The terminals according to the various embodiments disclosed in this document may take various forms. The terminals may include, for example, portable communication devices (e.g., smartphones), computer devices, portable multimedia devices, portable medical devices, cameras, wearable devices, or home appliances. The terminals according to the embodiments of this document are not limited to the aforementioned devices.

[0143] The various embodiments of this document and the terminology used therein are not intended to limit the technical features described in this document to specific embodiments, but should be understood to include various modifications, equivalents, or substitutes of the embodiments. In connection with the description of the drawings, similar reference numerals may be used for similar or related components. The singular form of a noun corresponding to an item may include one or more of the items, unless the context clearly indicates otherwise. In this document, each of the phrases "A or B", "at least one of A and B", "at least one of A or B", "A, B, or C", "at least one of A, B, and C", and "at least one of A, B, or C" can include any one of the items listed together in the corresponding phrase among those phrases, or all possible combinations thereof. Terms such as "first," "second," or "first" or "second" may be used merely to distinguish one component from another, and do not limit the components in any other respect (e.g., importance or order). When a component (e.g., a first component) is referred to as "coupled" or "connected" to another (e.g., a second component), with or without the terms "functionally" or "communicatively," it means that the component can be connected to the other component directly (e.g., wired), wirelessly, or through a third component.

[0144] The term "module" used in various embodiments of this document may include a unit implemented in hardware, software, or firmware, and may be used interchangeably with terms such as logic, logic block, component, or circuit. A module may be an integral component, or a minimum unit or part of such a component that performs one or more functions. For example, according to one embodiment, a module may be implemented in the form of an application-specific integrated circuit (ASIC).

[0145] Various embodiments of the present document may be implemented as software (e.g., a program) including one or more instructions stored in a storage medium (e.g., built-in memory or external memory) readable by a machine (e.g., an electronic device). For example, a processor (e.g., a processor) of the machine (e.g., an electronic device) may call at least one instruction among the one or more instructions stored from the storage medium and execute it. This enables the machine to operate to perform at least one function according to the at least one instruction called. The one or more instructions may include code generated by a compiler or code executable by an interpreter. The machine-readable storage medium may be provided in the form of a non-transitory storage medium. Here, non-transitory only means that the storage medium is a tangible device and does not contain a signal (e.g., electromagnetic waves), and this term does not distinguish between cases where data is stored semi-permanently and cases where it is stored temporarily in the storage medium.

[0146] According to one embodiment, the method according to various embodiments disclosed in the present document may be provided as included in a computer program product. The computer program product may be traded as a product between a seller and a buyer. The computer program product may be distributed in the form of a machine-readable storage medium (e.g., compact disc read-only memory (CD-ROM)), or may be distributed online (e.g., downloaded or uploaded) via an application store (e.g., Play Store™) or directly between two user devices (e.g., smart phones). In the case of online distribution, at least a portion of the computer program product may be temporarily stored or temporarily generated in a machine-readable storage medium, such as the memory of a manufacturer's server, an application store's server, or an intermediary server.

[0147] According to various embodiments, each component (e.g., a module or a program) of the above-described components may include one or more entities, and some of the entities may be separated and placed in other components. According to various embodiments, one or more components or operations of the aforementioned components may be omitted, or one or more other components or operations may be added. Alternatively or additionally, a plurality of components (e.g., a module or a program) may be integrated into a single component. In such a case, the integrated component may perform one or more functions of each of the plurality of components identically or similarly to those performed by the corresponding component among the plurality of components prior to the integration. According to various embodiments, the operations performed by a module, program, or other component may be executed sequentially, in parallel, iteratively, or heuristically, or one or more of the operations may be executed in a different order, omitted, or one or more other operations may be added.

Claims

1. A method performed in a wireless communication system, An operation of receiving a signal including DMRS (demodulation reference signal) symbols; An operation of estimating frequency domain channels corresponding to the above DMRS symbols; An operation of estimating a frequency offset for each antenna group based on information about the phase shift between the frequency domain channels and the antenna group; An operation of estimating a time domain channel based on a frequency offset for each antenna group; An operation of estimating noise for each antenna group based on the frequency domain channels, information about the antenna group, and frequency offset for each antenna group; An operation of obtaining a minimum mean squared error (MMSE) weight based on the noise and the time domain channel for each antenna group; and An operation of acquiring data by demodulating the signal based on the above MMSE weights. A method comprising:

2. In paragraph 1, Information about the above antenna group is: Contains the indices of the antennas that make up each antenna group, The frequency offset for each antenna group is: It is estimated based on the phase shift between the frequency domain channels calculated for each of the above antennas. method.

3. In either of paragraphs 1 and 2, Information about the above antenna group is: It is obtained based on the antenna-specific frequency offset stored before or estimated after the reception of the signal, Information about the antenna group obtained after receiving the above signal, It is obtained by grouping antennas based on the size of the frequency offset for each antenna, or by grouping antennas based on the sign of the frequency offset for each antenna, or by grouping antennas based on the K-means clustering algorithm using the size of the frequency offset for each antenna. method.

4. In any one of paragraphs 1 to 3, The operation of estimating noise for each antenna group is as follows: An operation of estimating a covariance matrix for noise for each antenna group based on information about the antenna group; An operation of updating the covariance matrix based on the frequency offset for each antenna group; and An operation to obtain the full covariance matrix based on the updated covariance matrix. A method comprising:

5. In any one of paragraphs 1 to 4, The operation of updating the above covariance matrix is: An operation of obtaining an average DMRS (demodulation reference signal) SNR (signal to noise ratio) of the above covariance matrix; The operation of comparing the above average DMRS SNR with a threshold value; and An operation of updating the covariance matrix based on the frequency offset for each antenna group when the average DMRS SNR is greater than or equal to the threshold value. A method comprising:

6. In any one of paragraphs 1 to 5, The operation of updating the above covariance matrix is: An operation of replacing off-diagonal elements of the covariance matrix with 0 when the absolute value of the frequency offset for each antenna group is greater than a threshold value; and An operation of maintaining the covariance matrix when the absolute value of the frequency offset for each antenna group is less than or equal to the threshold value. A method comprising:

7. In any one of paragraphs 1 to 6, The operation of updating the above covariance matrix is: An operation to correct the covariance matrix based on diagonal loading factors. Including, The above diagonal load variable is, is set to a value corresponding to the frequency offset for each antenna group, or It is set based on a table containing different diagonal load variables according to the above absolute values, method.

8. In any one of paragraphs 1 to 7, The above diagonal load variable is, If the absolute value of the frequency offset for each antenna group is less than or equal to the first threshold, it is set to 0. If the above absolute value is greater than or equal to the second threshold value, it is set to 1, If the absolute value is a value between the first threshold value and the second threshold value, it is set based on the first threshold value, the second threshold value, and the absolute value. method.

9. A computer program stored on a computer-readable recording medium to execute any one of the methods of claims 1 to 8 in combination with hardware.

10. At the base station, communication circuit; One or more processors operatively connected to the communication circuitry; and Memory that stores instructions Including, The above instructions, when individually or collectively executed by the one or more processors, cause the base station to: Receive a signal containing DMRS symbols, Estimate frequency domain channels corresponding to the above DMRS (demodulation reference signal) symbols, Based on the phase shift between the frequency domain channels and the information about the antenna group, the frequency offset is estimated for each antenna group, Based on the frequency offset for each antenna group, the time domain channel is estimated, Based on the frequency domain channels, information about the antenna group, and frequency offset for each antenna group, noise is estimated for each antenna group, Based on the noise for each antenna group and the time domain channel, a minimum mean squared error (MMSE) weight is obtained, To obtain data by demodulating the signal based on the above MMSE weights, Base station.

11. In paragraph 10, Information about the above antenna group is: Contains the indices of the antennas that make up each antenna group, The frequency offset for each antenna group is: It is estimated based on the phase shift between the frequency domain channels calculated for each of the above antennas. Base station.

12. In any one of paragraphs 10 and 11, Information about the above antenna group is: It is obtained based on the antenna-specific frequency offset stored before or estimated after the reception of the signal, Information about the antenna group obtained after receiving the above signal, It is obtained by grouping antennas based on the size of the frequency offset for each antenna, or by grouping antennas based on the sign of the frequency offset for each antenna, or by grouping antennas based on the K-means clustering algorithm using the size of the frequency offset for each antenna. Base station.

13. In any one of paragraphs 10 to 12, The above instructions, when individually or collectively executed by the one or more processors, cause the base station to: Based on the information about the antenna group, a covariance matrix for noise is estimated for each antenna group, Based on the frequency offset for each antenna group, the covariance matrix is ​​updated, Based on the updated covariance matrix, we obtain the full covariance matrix. Base station.

14. In any one of paragraphs 10 to 13, The above instructions, when individually or collectively executed by the one or more processors, cause the base station to: Obtain the average DMRS (demodulation reference signal) SNR (signal to noise ratio) of the above covariance matrix, Compare the above average DMRS SNR with the threshold, If the average DMRS SNR is greater than or equal to the threshold, the covariance matrix is ​​updated based on the frequency offset for each antenna group. Base station.

15. In any one of paragraphs 10 to 14, The above instructions, when individually or collectively executed by the one or more processors, cause the base station to: If the absolute value of the frequency offset for each antenna group is greater than the threshold, the off-diagonal elements of the covariance matrix are replaced with 0, If the absolute value of the frequency offset for each antenna group is less than or equal to the threshold value, the covariance matrix is ​​maintained. Base station.

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