WO2025174000A1 - Method performed by terminal or network in wireless communication system, and device therefor - Google Patents

Abstract

A method performed by a terminal, according to at least one from among embodiments disclosed in the present specification, comprises: receiving channel state information (CSI) configuration information through higher layer signaling; acquiring CSI from an artificial intelligence/machine learning (AI/ML) model on the basis of the CSI configuration information; and transmitting a CSI report on the basis of the CSI, wherein data input into the AI/ML model in order to acquire the CSI includes data about past CSI calculated prior to the CSI, and the CSI report can include information about a time window to which the past CSI belongs in a time domain.

Description

Method performed by a terminal or network in a wireless communication system and device therefor

The present disclosure relates to a wireless communication system, and more particularly, to a method and device for transmitting or receiving an uplink/downlink wireless signal by a terminal or a network in a wireless communication system.

Wireless communication systems are widely deployed to provide various types of communication services, such as voice and data. Typically, wireless communication systems are multiple access systems that support communication with multiple users by sharing available system resources (e.g., bandwidth, transmission power). Examples of multiple access systems include code division multiple access (CDMA), frequency division multiple access (FDMA), time division multiple access (TDMA), orthogonal frequency division multiple access (OFDMA), and single-carrier frequency division multiple access (SC-FDMA).

Recently, research is being conducted on CSI feedback based on AI/ML (artificial intelligence/machine learning) in NR standardization, and CSI compression to reduce CSI overhead through AI/ML models is being considered as one of the main research topics.

The technical task of this disclosure is to provide a method and device for efficiently performing wireless signal transmission and reception processes. For example, a method and device for performing CSI reporting more efficiently and accurately using an AI/ML model that utilizes past CSI as input can be provided.

In addition to the technical challenges described above, other technical challenges can be inferred from the description below.

According to one aspect of the present disclosure, a method performed by a terminal includes receiving CSI (channel state information) configuration information through upper layer signaling; acquiring CSI from an AI/ML (artificial intelligence/machine learning) model based on the CSI configuration information; and transmitting a CSI report based on the CSI, wherein data input to the AI/ML model to acquire the CSI includes data on past CSIs calculated before the CSI, and the CSI report may include information on a time window to which the past CSIs belong in the time domain.

The size of the above time window can be set through the above CSI setting information.

Data on the above past CSIs can be obtained by applying weights to the past CSIs determined within the time window. The CSI report can include information on the weights.

Data on the above past CSIs can be obtained by applying a time-frequency pattern to the past CSIs determined within the time window. The CSI report can include information on the time-frequency pattern.

The above past CSIs can be selected based on the coherency of the channel being maintained for the current point in time.

The terminal may flush its buffer for past CSIs based on the past CSIs being invalid for the current point in time. The terminal may transmit information to the network indicating the flushing of the buffer.

The above CSI report may further include Ground Truth CSI information indicating actual values of the above past CSIs.

The above CSI configuration information may include information on at least one of a pattern, granularity, or filter to be applied to the past CSIs to generate the Ground Truth CSI information.

According to another aspect of the present disclosure, a non-transitory computer-readable recording medium having recorded thereon a program for performing the method described above may be provided.

According to another aspect of the present disclosure, a device comprises: a memory configured to store instructions; and a processor configured to perform operations by executing the instructions, wherein the operations of the processor include receiving channel state information (CSI) configuration information through upper layer signaling; obtaining CSI from an artificial intelligence/machine learning (AI/ML) model based on the CSI configuration information; and transmitting a CSI report based on the CSI, wherein data input to the AI/ML model to obtain the CSI includes data on past CSIs that were calculated before the CSI, and the CSI report may include information on a time window to which the past CSIs belong in the time domain.

The above device may further include a transceiver.

The above device may be a terminal in a wireless communication system.

The above device may be a processing device configured to control a terminal in a wireless communication system.

According to another aspect of the present disclosure, a method performed by a base station includes transmitting channel state information (CSI) configuration information to a terminal through upper layer signaling; receiving a CSI report from the terminal based on the CSI configuration information; and reconstructing CSI calculated in a first AI/ML (artificial intelligence/machine learning) model of the terminal based on the CSI report in a second AI/ML model of the base station, wherein data input to the second AI/ML model for reconstructing the CSI includes data on past CSIs that were calculated before the CSI, and the CSI report may include information on a time window to which the past CSIs belong in the time domain.

According to another aspect of the present disclosure, a base station includes a memory configured to store instructions; and a processor configured to perform operations by executing the instructions, wherein the operations of the processor include transmitting channel state information (CSI) configuration information to a terminal through higher layer signaling; receiving a CSI report from the terminal based on the CSI configuration information; and reconstructing CSI calculated in a first AI/ML model of the terminal based on the CSI report in a second AI/ML model of the base station, wherein data input to the second AI/ML model to reconstruct the CSI includes data on past CSIs that were calculated before the CSI, and the CSI report may include information on a time window to which the past CSIs belong in the time domain.

According to the present disclosure, wireless signal transmission and reception can be efficiently performed in a wireless communication system. For example, the overhead of CSI reporting can be reduced through an AI/ML model that utilizes past CSI as input. Furthermore, by clearly defining the data range of past CSI, terminals and networks can operate without ambiguity.

In addition to the technical effects described above, other technical effects can be inferred from the description below.

Figure 1 illustrates physical channels used in a 3GPP system, which is an example of a wireless communication system, and a general signal transmission method using the channels.

Figure 2 illustrates the structure of a radio frame.

Figure 3 illustrates a resource grid of slots.

Figure 4 illustrates an example of physical channels being mapped within a slot.

Figure 5 illustrates the PDSCH and ACK/NACK transmission process.

Figure 6 illustrates a PUSCH transmission process.

Figure 7 shows an example of a CSI-related procedure.

Figure 8 is a diagram to explain the concept of AI/ML/Deep learning.

Figures 9 to 12 illustrate various AI/ML models of deep learning.

Figure 13 is a diagram illustrating segmentation AI inference.

Figure 14 is a diagram illustrating a framework for 3GPP RAN Intelligence.

Figures 15 to 17 illustrate AI Model Training and Inference environments.

Figure 18 is a diagram to explain the concept of AI/ML-based CSI compression.

Figure 19 is a diagram to explain the concept of AI/ML-based CSI prediction.

Figure 20 is a diagram for explaining AI/ML-based TSF-CSI compression according to one implementation.

Figure 21 illustrates examples of time/frequency patterns for Historical CSI according to one implementation.

Figure 22 is a diagram for explaining AI/ML-based Differential-CSI compression according to one implementation.

Figure 23 is a diagram for explaining the operation of a network and terminal according to one implementation.

Figure 24 illustrates a flow of a method performed by a terminal in a wireless communication system according to one embodiment.

Figure 25 illustrates a flowchart of a method performed by a base station in a wireless communication system according to one embodiment.

Figures 26 to 29 illustrate a communication system (1) and a wireless device applicable to the present disclosure.

The following technologies can be used in various wireless access systems, such as CDMA (code division multiple access), FDMA (frequency division multiple access), TDMA (time division multiple access), OFDMA (orthogonal frequency division multiple access), and SC-FDMA (single carrier frequency division multiple access). CDMA can be implemented with radio technologies such as UTRA (Universal Terrestrial Radio Access) or CDMA2000. TDMA can be implemented with radio technologies such as GSM (Global System for Mobile communications)/GPRS (General Packet Radio Service)/EDGE (Enhanced Data Rates for GSM Evolution). OFDMA can be implemented with radio technologies such as IEEE 802.11 (Wi-Fi), IEEE 802.16 (WiMAX), IEEE 802-20, and E-UTRA (Evolved UTRA). UTRA is a part of UMTS (Universal Mobile Telecommunications System). 3GPP (3rd Generation Partnership Project) LTE (long term evolution) is part of E-UMTS (Evolved UMTS) that uses E-UTRA, and LTE-A (Advanced) is an evolved version of 3GPP LTE. 3GPP NR (New Radio or New Radio Access Technology) is an evolved version of 3GPP LTE/LTE-A.

As more and more communication devices demand greater communication capacity, the need for improved mobile broadband communications compared to existing Radio Access Technology (RAT) is emerging. Furthermore, massive Machine Type Communications (MTC), which connects multiple devices and objects to provide diverse services anytime, anywhere, is also a key issue to be considered in next-generation communications. Furthermore, communication system design that considers reliability and latency-sensitive services/terminals is being discussed. Accordingly, the introduction of next-generation RATs that consider enhanced Mobile BroadBand Communication (eMBB), massive MTC, and Ultra-Reliable and Low Latency Communication (URLLC) is being discussed. For convenience, this technology is referred to as NR (New Radio or New RAT) in the present invention.

For clarity of explanation, the description will focus on 3GPP NR, but the technical idea of the present invention is not limited thereto.

In this specification, the expression "setting" can be replaced with the expression "configure/configuration", and the two can be used interchangeably. In addition, conditional expressions (e.g., "if", "in a case", or "when", etc.) can be replaced with the expressions "based on that ~~" or "in a state/status". In addition, the operation of the terminal/base station or the SW/HW configuration according to the satisfaction of the condition can be inferred/understood. In addition, if the process of the receiving (or transmitting) side can be inferred/understood from the process of the transmitting (or receiving) side in signal transmission/reception between wireless communication devices (e.g., base stations, terminals), the description thereof can be omitted. For example, signal determination/generation/encoding/transmission, etc. of the transmitting side can be understood as signal monitoring reception/decoding/determination, etc. of the receiving side. In addition, the expression that the terminal performs (or does not perform) a specific operation can also be interpreted as meaning that the base station operates while expecting/assuming (or expecting/assuming that the terminal does not perform) the specific operation. In addition, the expression that the base station performs (or does not perform) a specific operation can also be interpreted as meaning that the terminal operates while expecting/assuming (or expecting/assuming that the base station does not perform) the specific operation. In addition, the division and index of each section, embodiment, example, option, method, plan, etc. in the following description are for the convenience of explanation and should not be interpreted as meaning that each constitutes an independent invention or that each must be implemented only individually. In addition, in describing each section, embodiment, example, option, method, plan, etc., if there is no explicitly conflicting/opposing description, it can be inferred/interpreted that at least some of them can be combined and implemented together, or at least some can be implemented with the omission of each.

In a wireless communication system, a terminal receives information from a base station via the downlink (DL) and transmits it to the base station via the uplink (UL). The information transmitted and received between the base station and the terminal includes data and various control information, and various physical channels exist depending on the type and purpose of the information being transmitted and received.

Figure 1 is a drawing for explaining physical channels used in a 3GPP NR system and a general signal transmission method using them.

When a terminal is powered on again from a powered-off state or enters a new cell, it performs an initial cell search operation, such as synchronizing with the base station, in step S101. To this end, the terminal receives a Synchronization Signal Block (SSB) from the base station. The SSB includes a Primary Synchronization Signal (PSS), a Secondary Synchronization Signal (SSS), and a Physical Broadcast Channel (PBCH). Based on the PSS/SSS, the terminal synchronizes with the base station and obtains information such as a cell ID (cell identity). In addition, the terminal can obtain broadcast information within the cell based on the PBCH. Meanwhile, the terminal can check the downlink channel status by receiving a Downlink Reference Signal (DL RS) during the initial cell search phase.

After completing the initial cell search, the terminal can obtain more specific system information by receiving a physical downlink control channel (PDCCH) and a physical downlink shared channel (PDSCH) based on the physical downlink control channel information in step S102.

Thereafter, the terminal may perform a random access procedure such as steps S103 to S106 to complete connection to the base station. To this end, the terminal may transmit a preamble through a physical random access channel (PRACH) (S103) and receive a response message to the preamble through a physical downlink control channel and a corresponding physical downlink shared channel (S104). In the case of contention-based random access, a contention resolution procedure such as transmission of an additional physical random access channel (S105) and reception of a physical downlink control channel and a corresponding physical downlink shared channel (S106) may be performed.

The terminal that has performed the procedure as described above can then perform the general uplink/downlink signal transmission procedure, such as receiving a physical downlink control channel/physical downlink shared channel (S107) and transmitting a physical uplink shared channel (PUSCH)/physical uplink control channel (PUCCH) (S108). The control information that the terminal transmits to the base station is collectively referred to as uplink control information (UCI). UCI includes HARQ ACK/NACK (Hybrid Automatic Repeat and request Acknowledgement/Negative-ACK), SR (Scheduling Request), CSI (Channel State Information), etc. CSI includes CQI (Channel Quality Indicator), PMI (Precoding Matrix Indicator), RI (Rank Indication), etc. UCI is generally transmitted through PUCCH, but can be transmitted through PUSCH when control information and traffic data must be transmitted simultaneously. Additionally, UCI can be transmitted aperiodically via PUSCH upon request/instruction from the network.

Figure 2 illustrates the structure of a radio frame. In NR, uplink and downlink transmissions are organized into frames. Each radio frame is 10 ms long and is divided into two 5 ms half-frames (HF). Each half-frame is divided into five 1 ms sub-frames (SF). A sub-frame is divided into one or more slots, and the number of slots within a sub-frame depends on the subcarrier spacing (SCS). Each slot contains 12 or 14 OFDM (Orthogonal Frequency Division Multiplexing) symbols, depending on the cyclic prefix (CP). When a normal CP is used, each slot contains 14 OFDM symbols. When an extended CP is used, each slot contains 12 OFDM symbols.

Table 1 illustrates that when CP is normally used, the number of symbols per slot, the number of slots per frame, and the number of slots per subframe vary depending on the SCS.

SCS (15*2^u) N ^slot _symb N ^frame,u _slot N ^{subframes, u} _slots 15KHz (u=0) 14 10 1 30KHz (u=1) 14 20 2 60KHz (u=2) 14 40 4 120KHz (u=3) 14 80 8 240KHz (u=4) 14 160 16

* N ^slot _symb : Number of symbols in the slot

* N ^frame,u _slot : Number of slots in a frame

* N ^subframe,u _slot : number of slots in a subframe

Table 2 illustrates that when extended CP is used, the number of symbols per slot, the number of slots per frame, and the number of slots per subframe vary depending on the SCS.

SCS (15*2^u) N ^slot _symb N ^frame,u _slot N ^{subframes, u} _slots 60KHz (u=2) 12 40 4

The structure of the frame is only an example, and the number of subframes, number of slots, and number of symbols in the frame can be varied.

In an NR system, OFDM numerology (e.g., SCS) may be set differently between multiple cells that are merged into a single terminal. Accordingly, the (absolute time) interval of a time resource (e.g., SF, slot, or TTI) (conveniently referred to as TU (Time Unit)) consisting of the same number of symbols may be set differently between the merged cells. Here, the symbol may include an OFDM symbol (or CP-OFDM symbol), an SC-FDMA symbol (or Discrete Fourier Transform-spread-OFDM, DFT-s-OFDM symbol).

Figure 3 illustrates a resource grid of a slot. A slot contains multiple symbols in the time domain. For example, in the case of a regular CP, one slot contains 14 symbols, but in the case of an extended CP, one slot contains 12 symbols. A carrier contains multiple subcarriers in the frequency domain. A Resource Block (RB) is defined as multiple (e.g., 12) consecutive subcarriers in the frequency domain. A Bandwidth Part (BWP) is defined as multiple consecutive Physical RBs (PRBs) in the frequency domain and can correspond to a single numerology (e.g., SCS, CP length, etc.). A carrier can contain up to N (e.g., 5) BWPs. Data communication is performed through activated BWPs, and only one BWP can be activated for a single terminal. Each element in the resource grid is referred to as a Resource Element (RE), to which one complex symbol can be mapped.

Figure 4 illustrates an example of how physical channels are mapped within a slot. A PDCCH can be transmitted in the DL control region, and a PDSCH can be transmitted in the DL data region. A PUCCH can be transmitted in the UL control region, and a PUSCH can be transmitted in the UL data region. GP provides a time gap between the base station and the terminal when switching from transmission mode to reception mode or from reception mode to transmission mode. Some symbols within a subframe at the time of transition from DL to UL can be set as GP.

Below, each physical channel is described in more detail.

The PDCCH carries Downlink Control Information (DCI). For example, the PCCCH (i.e., DCI) carries the transmission format and resource allocation of the downlink shared channel (DL-SCH), resource allocation information for the uplink shared channel (UL-SCH), paging information for the paging channel (PCH), system information on the DL-SCH, resource allocation information for upper layer control messages such as random access responses transmitted on the PDSCH, transmission power control commands, activation/deactivation of Configured Scheduling (CS), etc. The DCI includes a cyclic redundancy check (CRC), which is masked/scrambled with various identifiers (e.g., Radio Network Temporary Identifier, RNTI) depending on the owner or usage of the PDCCH. For example, if the PDCCH is for a specific terminal, the CRC is masked with a terminal identifier (e.g., Cell-RNTI, C-RNTI). If the PDCCH is for paging, the CRC is masked with the Paging-RNTI (P-RNTI). If the PDCCH is for system information (e.g., a System Information Block, SIB), the CRC is masked with the System Information RNTI (SI-RNTI). If the PDCCH is for a random access response, the CRC is masked with the Random Access-RNTI (RA-RNTI).

The PDCCH consists of 1, 2, 4, 8, or 16 Control Channel Elements (CCEs) depending on the Aggregation Level (AL). A CCE is a logical allocation unit used to provide a PDCCH with a predetermined code rate depending on the radio channel status. A CCE consists of six Resource Element Groups (REGs). A REG is defined as one OFDM symbol and one (P)RB. The PDCCH is transmitted through a Control Resource Set (CORESET). A CORESET is defined as a set of REGs with a given numerology (e.g., SCS, CP length, etc.). Multiple CORESETs for a single UE can overlap in the time/frequency domain. A CORESET can be configured through system information (e.g., Master Information Block, MIB) or UE-specific upper layer (e.g., Radio Resource Control, RRC, layer) signaling. Specifically, the number of RBs and the number of OFDM symbols (up to 3) that constitute the CORESET can be set by upper layer signaling.

To receive/detect PDCCH, the UE monitors PDCCH candidates. PDCCH candidates represent the CCE(s) that the UE should monitor for PDCCH detection. Each PDCCH candidate is defined as 1, 2, 4, 8, or 16 CCEs depending on the AL. Monitoring involves (blind) decoding the PDCCH candidates. The set of PDCCH candidates that the UE monitors is defined as a PDCCH Search Space (SS). The search space includes a Common Search Space (CSS) or a UE-specific search space (USS). The UE can acquire DCI by monitoring PDCCH candidates in one or more search spaces configured by the MIB or higher-layer signaling. Each CORESET is associated with one or more search spaces, and each search space is associated with one COREST. The search space can be defined based on the following parameters.

- controlResourceSetId: Indicates the CORESET associated with the search space.

- monitoringSlotPeriodicityAndOffset: Indicates the PDCCH monitoring period (in slots) and the PDCCH monitoring interval offset (in slots).

- monitoringSymbolsWithinSlot: Indicates the PDCCH monitoring symbols within the slot (e.g., the first symbol(s) of the CORESET).

- nrofCandidates: AL={1, 2, 4, 8, 16} indicates the number of PDCCH candidates (one of 0, 1, 2, 3, 4, 5, 6, 8)

* An opportunity (e.g., time/frequency resource) for monitoring PDCCH candidates is defined as a PDCCH (monitoring) opportunity. One or more PDCCH (monitoring) opportunities can be configured within a slot.

Table 3 illustrates the characteristics of each search space type.

Type Search Space RNTI Use Case Type0-PDCCH Common SI-RNTI on a primary cell SIB Decoding Type0A-PDCCH Common SI-RNTI on a primary cell SIB Decoding Type1-PDCCH Common RA-RNTI or TC-RNTI on a primary cell Msg2, Msg4 decoding in RACH Type2-PDCCH Common P-RNTI on a primary cell Paging Decoding Type3-PDCCH Common INT-RNTI, SFI-RNTI, TPC-PUSCH-RNTI, TPC-PUCCH-RNTI, TPC-SRS-RNTI, C-RNTI, MCS-C-RNTI, or CS-RNTI(s) UE Specific UE Specific C-RNTI, or MCS-C-RNTI, or CS-RNTI(s) User-specific PDSCH decoding

Table 4 illustrates DCI formats transmitted via PDCCH.

DCI format Usage 0_0 Scheduling of PUSCH in one cell 0_1 Scheduling of PUSCH in one cell 1_0 Scheduling of PDSCH in one cell 1_1 Scheduling of PDSCH in one cell 2_0 Notifying a group of UEs of the slot format 2_1 Notifying a group of UEs of the PRB(s) and OFDM symbol(s) where UE may assume no transmission is intended for the UE 2_2 Transmission of TPC commands for PUCCH and PUSCH 2_3 Transmission of a group of TPC commands for SRS transmissions by one or more UEs

DCI format 0_0 is used to schedule a TB-based (or TB-level) PUSCH, and DCI format 0_1 can be used to schedule a TB-based (or TB-level) PUSCH or a CBG (Code Block Group)-based (or CBG-level) PUSCH. DCI format 1_0 is used to schedule a TB-based (or TB-level) PDSCH, and DCI format 1_1 can be used to schedule a TB-based (or TB-level) PDSCH or a CBG-based (or CBG-level) PDSCH (DL grant DCI). DCI format 0_0/0_1 may be referred to as UL grant DCI or UL scheduling information, and DCI format 1_0/1_1 may be referred to as DL grant DCI or DL scheduling information. DCI format 2_0 is used to convey dynamic slot format information (e.g., dynamic SFI) to the terminal, and DCI format 2_1 is used to convey downlink pre-emption information to the terminal. DCI format 2_0 and/or DCI format 2_1 can be conveyed to the terminals within a group through the group common PDCCH, which is a PDCCH conveyed to the terminals defined as a group.

DCI format 0_0 and DCI format 1_0 may be referred to as fallback DCI formats, while DCI format 0_1 and DCI format 1_1 may be referred to as non-fallback DCI formats. In the fallback DCI format, the DCI size/field configuration remains the same regardless of the terminal configuration. On the other hand, in the non-fallback DCI format, the DCI size/field configuration varies depending on the terminal configuration.

PDSCH carries downlink data (e.g., DL-SCH transport block, DL-SCH TB) and applies modulation methods such as Quadrature Phase Shift Keying (QPSK), 16 Quadrature Amplitude Modulation (QAM), 64 QAM, and 256 QAM. TB is encoded to generate a codeword. PDSCH can carry up to two codewords. Scrambling and modulation mapping are performed for each codeword, and modulation symbols generated from each codeword can be mapped to one or more layers. Each layer is mapped to resources along with a Demodulation Reference Signal (DMRS), generated as an OFDM symbol signal, and transmitted through the corresponding antenna port.

PUCCH carries Uplink Control Information (UCI). UCI includes:

- SR (Scheduling Request): Information used to request UL-SCH resources.

- HARQ(Hybrid Automatic Repeat reQuest)-ACK(Acknowledgement): This is a response to a downlink data packet (e.g., codeword) on the PDSCH. It indicates whether the downlink data packet was successfully received. One HARQ-ACK bit can be transmitted in response to a single codeword, and two HARQ-ACK bits can be transmitted in response to two codewords. The HARQ-ACK response includes a positive ACK (simply, ACK), a negative ACK (NACK), a DTX, or a NACK/DTX. Here, HARQ-ACK is used interchangeably with HARQ ACK/NACK and ACK/NACK.

- CSI (Channel State Information): Feedback information for the downlink channel. MIMO (Multiple Input Multiple Output)-related feedback information includes the Rank Indicator (RI) and Precoding Matrix Indicator (PMI).

Table 5 illustrates PUCCH formats. Depending on the PUCCH transmission length, they can be classified into Short PUCCH (formats 0 and 2) and Long PUCCH (formats 1, 3, and 4).

PUCCH format Length in OFDM symbols N ^PUCCH _symb Number of bits Usage Etc 0 1 - 2 ≤2 HARQ, SR Sequence selection 1 4 - 14 ≤2 HARQ, [SR] Sequence modulation 2 1 - 2 >2 HARQ, CSI, [SR] CP-OFDM 3 4 - 14 >2 HARQ, CSI, [SR] DFT-s-OFDM
(no UE multiplexing) 4 4 - 14 >2 HARQ, CSI, [SR] DFT-s-OFDM
(Pre DFT OCC)

PUCCH format 0 carries UCI of up to 2 bits in size and is mapped and transmitted based on sequence. Specifically, the terminal transmits a specific UCI to the base station by transmitting one of multiple sequences through the PUCCH of PUCCH format 0. The terminal transmits the PUCCH of PUCCH format 0 within the PUCCH resources for the corresponding SR configuration only when transmitting a positive SR.

PUCCH format 1 carries UCI of up to 2 bits in size, and modulation symbols are spread in the time domain using an orthogonal cover code (OCC) (which is set differently depending on whether frequency hopping is used). DMRS are transmitted in symbols where modulation symbols are not transmitted (i.e., transmitted using Time Division Multiplexing (TDM).

PUCCH format 2 carries UCI with a bit size greater than 2 bits, and modulation symbols are transmitted by frequency division multiplexing (FDM) with DMRS. DM-RSs are located at symbol indices #1, #4, #7, and #10 within a given resource block with a density of 1/3. Pseudo Noise (PN) sequences are used for DM_RS sequences. Frequency hopping can be enabled for 2-symbol PUCCH format 2.

PUCCH format 3 does not multiplex terminals within the same physical resource blocks and carries UCI with a bit size greater than 2 bits. In other words, PUCCH resources in PUCCH format 3 do not include orthogonal cover codes. Modulation symbols are transmitted through time division multiplexing (TDM) with DMRS.

PUCCH format 4 supports multiplexing of up to four terminals within the same physical resource blocks and carries UCI with a bit size greater than 2 bits. In other words, PUCCH resources in PUCCH format 3 include orthogonal cover codes. Modulation symbols are transmitted through time division multiplexing (TDM) with DMRS.

At least one of one or more configured cells in a terminal may be configured for PUCCH transmission. At least the primary cell may be configured as a cell for PUCCH transmission. At least one PUCCH cell group may be configured in the terminal based on at least one cell configured for PUCCH transmission, and each PUCCH cell group includes one or more cells. The PUCCH cell group may be simply referred to as a PUCCH group. PUCCH transmission may be configured not only for the primary cell but also for the SCell, and the primary cell belongs to the primary PUCCH group, and the PUCCH-SCell configured for PUCCH transmission belongs to the secondary PUCCH group. For cells belonging to the primary PUCCH group, the PUCCH on the primary cell may be used, and for cells belonging to the secondary PUCCH group, the PUCCH on the PUCCH-SCell may be used.

PUSCH carries uplink data (e.g., UL-SCH transport block, UL-SCH TB) and/or uplink control information (UCI), and is transmitted based on a CP-OFDM (Cyclic Prefix - Orthogonal Frequency Division Multiplexing) waveform or a DFT-s-OFDM (Discrete Fourier Transform - spread - Orthogonal Frequency Division Multiplexing) waveform. When the PUSCH is transmitted based on a DFT-s-OFDM waveform, the UE transmits the PUSCH by applying transform precoding. For example, when transform precoding is disabled (e.g., transform precoding is disabled), the UE transmits the PUSCH based on the CP-OFDM waveform, and when transform precoding is enabled (e.g., transform precoding is enabled), the UE can transmit the PUSCH based on the CP-OFDM waveform or the DFT-s-OFDM waveform. PUSCH transmissions can be dynamically scheduled by UL grants in DCI, or semi-statically scheduled (configured grant) based on higher layer (e.g., RRC) signaling (and/or Layer 1 (L1) signaling (e.g., PDCCH)). PUSCH transmissions can be performed in a codebook-based or non-codebook-based manner.

Figure 5 illustrates an ACK/NACK transmission process. Referring to Figure 5, a terminal can detect a PDCCH in slot #n. Here, the PDCCH includes downlink scheduling information (e.g., DCI formats 1_0, 1_1), and the PDCCH indicates a DL assignment-to-PDSCH offset (K0) and a PDSCH-HARQ-ACK reporting offset (K1). For example, DCI formats 1_0, 1_1 can include the following information:

- Frequency domain resource assignment: Indicates the set of RBs allocated to the PDSCH.

- Time domain resource assignment: K0 (e.g., slot offset), indicates the starting position of the PDSCH within slot #n+K0 (e.g., OFDM symbol index), and the length of the PDSCH (e.g., number of OFDM symbols).

- PDSCH-to-HARQ_feedback timing indicator: Indicates K1

- HARQ process number (4 bits): Indicates the HARQ process ID (Identity) for data (e.g., PDSCH, TB)

- PUCCH resource indicator (PRI): Indicates the PUCCH resource to be used for UCI transmission among multiple PUCCH resources within the PUCCH resource set.

Afterwards, the terminal receives PDSCH from slot #(n+K0) according to the scheduling information of slot #n, and when reception of PDSCH is finished in slot #n1 (where, n+K0≤n1), UCI can be transmitted through PUCCH in slot #(n1+K1). Here, UCI may include HARQ-ACK response for PDSCH. In Fig. 5, for convenience, it is assumed that SCS for PDSCH and SCS for PUCCH are the same and slot # n1 = slot #n+K0, but the present invention is not limited thereto. If the SCSs are different, K1 can be indicated/interpreted based on the SCS of PUCCH.

When the PDSCH is configured to transmit at most 1 TB, the HARQ-ACK response may consist of 1 bit. When the PDSCH is configured to transmit at most 2 TB, the HARQ-ACK response may consist of 2 bits if spatial bundling is not configured, and may consist of 1 bit if spatial bundling is configured. When the HARQ-ACK transmission timing for multiple PDSCHs is designated as slot #(n+K1), the UCI transmitted in slot #(n+K1) includes HARQ-ACK responses for multiple PDSCHs.

Whether a UE should perform spatial bundling for a HARQ-ACK response can be configured (e.g., RRC/higher layer signaling) for each cell group. For example, spatial bundling can be individually configured for each HARQ-ACK response transmitted over the PUCCH and/or each HARQ-ACK response transmitted over the PUSCH.

Spatial bundling can be supported when the maximum number of TBs (or codewords) that can be received at a time (or scheduled via 1 DCI) in the serving cell is 2 (or more than 2) (e.g., when the upper layer parameter maxNrofCodeWordsScheduledByDCI corresponds to 2-TB). Meanwhile, more than 4 layers can be used for 2-TB transmission, and up to 4 layers can be used for 1-TB transmission. Consequently, when spatial bundling is configured for the cell group, spatial bundling can be performed for serving cells that can schedule more than 4 layers among the serving cells in the cell group. On the serving cell, a UE that wishes to transmit a HARQ-ACK response via spatial bundling can generate the HARQ-ACK response by performing a (bit-wise) logical AND operation on the A/N bits for multiple TBs.

For example, assuming that a terminal receives a DCI scheduling 2 TB and receives 2 TB via PDSCH based on the DCI, the terminal performing spatial bundling can generate a single A/N bit by logically ANDing the first A/N bit for the first TB and the second A/N bit for the second TB. Consequently, if both the first TB and the second TB are ACK, the terminal reports the ACK bit value to the base station, and if either TB is NACK, the terminal reports the NACK bit value to the base station.

For example, if only 1-TB is actually scheduled on a serving cell configured to receive 2-TB, the terminal can generate a single A/N bit by logically ANDing the A/N bit for the 1-TB with bit value 1. Consequently, the terminal reports the A/N bit for the 1-TB to the base station as is.

A base station/terminal has multiple parallel DL HARQ processes for DL transmission. These multiple parallel HARQ processes allow DL transmissions to be performed continuously while waiting for HARQ feedback regarding the success or failure of the previous DL transmission. Each HARQ process is associated with a HARQ buffer in the MAC (Medium Access Control) layer. Each DL HARQ process manages state variables such as the number of transmissions of MAC Physical Data Blocks (PDUs) in the buffer, HARQ feedback for MAC PDUs in the buffer, and the current redundancy version. Each HARQ process is identified by a HARQ process ID.

Figure 6 illustrates a PUSCH transmission process. Referring to Figure 6, a terminal can detect a PDCCH in slot #n. Here, the PDCCH includes uplink scheduling information (e.g., DCI formats 0_0 and 0_1). DCI formats 0_0 and 0_1 can include the following information.

- Frequency domain resource assignment: Indicates the set of RBs allocated to PUSCH.

- Time domain resource assignment: Slot offset K2 indicates the starting position (e.g., symbol index) and length (e.g., number of OFDM symbols) of the PUSCH within the slot. The starting symbol and length can be indicated through SLIV (Start and Length Indicator Value) or can be indicated separately.

Thereafter, the terminal can transmit a PUSCH in slot #(n+K2) according to the scheduling information of slot #n. Here, the PUSCH includes a UL-SCH TB.

CSI-related actions

Figure 7 shows an example of a CSI-related procedure.

The terminal receives configuration information related to CSI from the base station via RRC signaling (710). The configuration information related to CSI may include at least one of CSI-IM (interference management) resource-related information, CSI measurement configuration-related information, CSI resource configuration-related information, CSI-RS resource-related information, or CSI report configuration-related information.

- CSI-IM resources can be configured for interference measurement (IM) of the terminal. In the time domain, the CSI-IM resource set can be configured periodically, semi-persistently, or aperiodicly. The CSI-IM resources can be configured as Zero Power (ZP)-CSI-RS for the terminal. The ZP-CSI-RS can be configured separately from the Non-Zero Power (NZP)-CSI-RS.

- The UE may assume that the CSI-RS resource(s) for channel measurement configured for one CSI reporting and the CSI-IM / NZP CSI-RS resource(s) for interference measurement (when NZP CSI-RS resource(s) are used for interference measurement) are in a QCL relationship with respect to 'QCL-TypeD' per resource.

- The CSI resource configuration may include at least one of a CSI-IM resource for interference measurement, an NZP CSI-RS resource for interference measurement, and an NZP CSI-RS resource for channel measurement. The CMR (channel measurement resource) may be an NZP CSI-RS for CSI acquisition, and the IMR (Interference measurement resource) may be an NZP CSI-RS for CSI-IM and IM.

- CSI-RS can be configured for one or more terminals. Different CSI-RS configurations may be provided for each terminal, or the same CSI-RS configuration may be provided to multiple terminals. CSI-RS can support up to 32 antenna ports. CSI-RS corresponding to N (N is 1 or greater) antenna ports can be mapped to N RE locations within a time-frequency unit corresponding to one slot and one RB. When N is 2 or greater, N-port CSI-RS can be multiplexed using CDM, FDM, and/or TDM schemes. CSI-RS can be mapped to REs other than REs to which CORESET, DMRS, and SSB are mapped. In the frequency domain, CSI-RS can be configured for the entire bandwidth, a portion of the bandwidth (BWP), or a portion of the bandwidth. CSI-RS may be transmitted in each RB within the bandwidth for which CSI-RS is configured (i.e., density = 1), or in every second RB (e.g., even or odd RB) (i.e., density = 1/2). When CSI-RS is used as a Tracking Reference Signal (TRS), a single-port CSI-RS may be mapped on three subcarriers in each resource block (i.e., density = 3). One or more CSI-RS resource sets may be configured for a UE in the time domain. Each CSI-RS resource set may include one or more CSI-RS configurations. Each CSI-RS resource set may be configured periodically, semi-persistently, or aperiodicly.

- The CSI report configuration may include configurations for feedback type, measurement resources, report type, etc. The NZP-CSI-RS resource set may be used for the CSI report configuration of the corresponding terminal. The NZP-CSI-RS resource set may be associated with CSI-RS or SSB. In addition, multiple periodic NZP-CSI-RS resource sets may be configured as TRS resource sets. (i) The feedback type may include a Channel Quality Indicator (CQI), a Precoding Matrix Indicator (PMI), a CSI-RS Resource Indicator (CRI), an SSB Resource block Indicator (SSBRI), a Layer Indicator (LI), a Rank Indicator (RI), a Layer 1-Reference Signal Received Strength (RSRP), etc. (ii) Measurement resources may include configurations for downlink signals and/or downlink resources on which the terminal performs measurements to determine feedback information. The measurement resources may be configured as ZP and/or NZP CSI-RS resource sets associated with CSI reporting configurations. The NZP CSI-RS resource set may include a CSI-RS set or an SSB set. For example, L1-RSRP may be measured for a CSI-RS set or an SSB set. (iii) Reporting types may include configurations for a time point at which the terminal performs reporting and an uplink channel, etc. The reporting time point may be configured as periodic, semi-persistent, or aperiodic. Periodic CSI reporting may be transmitted on PUCCH. Semi-persistent CSI reporting may be transmitted on PUCCH or PUSCH based on a MAC CE indicating activation/deactivation. Aperiodic CSI reporting may be indicated by DCI signaling. For example, the CSI request field of an uplink grant may indicate one of several report trigger sizes. Aperiodic CSI reports may be transmitted on the PUSCH.

The terminal measures CSI based on configuration information related to CSI. CSI measurement may include a procedure of receiving a CSI-RS (720) and computing the received CSI-RS to acquire CSI (730).

The UE can transmit a CSI report to the base station (740). For the CSI report, the time and frequency resources that the UE can use are controlled by the base station. The CSI (channel state information) can include at least one of a channel quality indicator (CQI), a precoding matrix indicator (PMI), a CSI-RS resource indicator (CRI), an SS/PBCH block resource indicator (SSBRI), a layer indicator (LI), a rank indicator (RI), L1-RSRP, and/or L-SINR.

The time domain behavior of CSI reporting supports periodic, semi-persistent, and aperiodic. i) Periodic CSI reporting is performed on short PUCCH and long PUCCH. The periodicity and slot offset of periodic CSI reporting can be configured by RRC, and refer to the CSI-ReportConfig IE. ii) SP (semi-periodic) CSI reporting is performed on short PUCCH, long PUCCH, or PUSCH. In case of SP CSI on short/long PUCCH, the periodicity and slot offset are configured by RRC, and CSI reporting is activated/deactivated by separate MAC CE/DCI. In case of SP CSI on PUSCH, the periodicity of SP CSI reporting is configured by RRC, but the slot offset is not configured by RRC, and SP CSI reporting is activated/deactivated by DCI (format 0_1). For SP CSI reporting on PUSCH, a separate RNTI (SP-CSI C-RNTI) is used. The initial CSI reporting timing follows the PUSCH time domain allocation value indicated in the DCI, and the subsequent CSI reporting timings follow the cycle set by RRC. DCI format 0_1 includes a CSI request field and can activate/deactivate a specific configured SP-CSI trigger state. SP CSI reporting has the same or similar activation/deactivation mechanism as the data transmission mechanism on SPS PUSCH. iii) Aperiodic CSI reporting is performed on PUSCH and is triggered by DCI. In this case, information related to the trigger of aperiodic CSI reporting can be transmitted/indicated/configured via MAC-CE. For AP CSI with AP CSI-RS, the AP CSI-RS timing is configured by RRC, and the timing for AP CSI reporting is dynamically controlled by DCI.

CSI codebooks defined in the NR standard (e.g., PMI codebooks) can be broadly divided into Type I and Type II codebooks. Type I codebooks are primarily targeted at SU (Single User)-MIMO, which supports both high-order and low-order signals. Type II codebooks can primarily support MI-MIMO, which supports up to two layers. Compared to Type I, Type II codebooks can provide more accurate CSI, but may increase signaling overhead. Meanwhile, Enhanced Type II codebooks were introduced to address the CSI overhead shortcomings of existing Type II codebooks. Enhanced Type II codebooks were introduced by reducing the codebook payload by considering the correlation of the frequency axis.

CSI reporting via PUSCH can be configured as Part 1 and Part 2. Part 1 has a fixed payload size and is used to identify the number of information bits in Part 2. Part 1 is transmitted in its entirety before Part 2.

- For Type I CSI feedback, Part 1 contains the RI (if reported), the CRI (if reported), and the CQI of the first code word. Part 2 contains the PMI, and when RI > 4, Part 2 contains the CQI.

- For Type II CSI feedback, Part 1 contains the RI (if reported), CQI, and an indication of the number of non-zero WB amplitude coefficients per layer of Type II CSI. Part 2 contains the PMI of Type II CSI.

- For Enhanced Type II CSI feedback, Part 1 contains the RI (if reported), CQI, and the total number of non-zero WB amplitude coefficients for all layers of Enhanced Type II CSI. Part 2 contains the PMI of Enhanced Type II CSI.

If CSI reporting on PUSCH includes two parts and the CSI payload to be reported is less than the payload size provided by the PUSCH resources allocated for CSI reporting, the UE may omit part of Part 2 CSI.

Meanwhile, semi-persistent CSI reporting performed in PUCCH format 3 or 4 supports Type II CSI feedback, but only Part 1 of Type II CSI feedback.

QCL (quasi-co location)

Two antenna ports are quasi-co-located if the channel properties of one antenna port can be inferred from the channel properties of the other antenna port. The channel properties may include one or more of Delay spread, Doppler spread, Frequency/Doppler shift, Average received power, Received Timing/average delay, and Spatial RX parameters.

A terminal can configure a list of multiple TCI-State configurations via the upper layer parameter PDSCH-Config. Each TCI-State is associated with one or two DL reference signals and a QCL configuration parameter between the DM-RS port of the PDSCH. The QCL can include qcl-Type1 for the first DL RS and qcl-Type2 for the second DL RS. The QCL type can correspond to one of the following:

- 'QCL-TypeA': {Doppler shift, Doppler spread, average delay, delay spread}

- 'QCL-TypeB': {Doppler shift, Doppler spread}

- 'QCL-TypeC': {Doppler shift, average delay}

- 'QCL-TypeD': {Spatial Rx parameter}

Beam Management (BM)

The BM process is a process for acquiring and maintaining a set of BS (or transmission and reception point (TRP)) and/or UE beams that can be used for downlink (DL) and uplink (UL) transmission/reception, and may include the following processes and terms.

- Beam measurement: An operation in which a BS or UE measures the characteristics of a received beamforming signal.

- Beam determination: An operation in which a BS or UE selects its own transmit beam (Tx beam) / receive beam (Rx beam).

- Beam sweeping: An operation of covering a spatial domain using transmit and/or receive beams over a predetermined time interval in a predetermined manner.

- Beam report: An operation in which a UE reports information about a beamformed signal based on beam measurement.

The BM process can be divided into (1) a DL BM process using SSB or CSI-RS, and (2) a UL BM process using SRS (sounding reference signal). In addition, each BM process can include Tx beam sweeping to determine a Tx beam and Rx beam sweeping to determine an Rx beam.

At this time, the DL BM process may include (1) transmission of beamformed DL RSs (e.g., CSI-RS or SSB) by the BS and (2) beam reporting by the UE.

Here, the beam report may include preferred DL RS ID(s) and corresponding reference signal received power (RSRP). The DL RS ID may be an SSB Resource Indicator (SSBRI) or a CSI-RS Resource Indicator (CRI).

Positioning

Positioning may refer to determining the geographic location and/or velocity of a UE by measuring radio signals. Position information may be requested by a client (e.g., an application) associated with the UE and reported to the client. Furthermore, the location information may be contained within the core network or requested by a client connected to the core network. The location information may be reported in a standard format, such as cell-based or geographic coordinates, and may also include an estimated error value for the UE's position and velocity and/or the positioning method used for positioning.

LPP can be used as a point-to-point between a location server (E-SMLC and/or SLP and/or LMF) and a target device (UE and/or SET) to position the target device using position-related measurements obtained from one or more reference sources. Through LPP, the target device and the location server can exchange measurement and/or position information based on Signal A and/or Signal B.

NRPPa can be used to exchange information between a reference source (ACCESS NODE and/or BS and/or TP and/or NG-RAN node) and a location server.

The functions provided by the NRPPa protocol may include:

- E-CID Location Information Transfer. This function allows location information to be exchanged between the reference source and the LMF for E-CID positioning purposes.

- OTDOA Information Transfer. This function allows information to be exchanged between the reference source and the LMF for OTDOA positioning purposes.

- Reporting of General Error Situations. This feature allows reporting of general error situations for which no function-specific error message is defined.

The positioning methods supported by NG-RAN may include GNSS (Global Navigation Satellite System), OTDOA, E-CID (enhanced cell ID), barometric positioning, WLAN positioning, Bluetooth positioning, terrestrial beacon system (TBS), and UTDOA (Uplink Time Difference of Arrival). Among the above positioning methods, the position of the UE may be measured using any one of the positioning methods, but the position of the UE may also be measured using two or more positioning methods.

OTDOA (Observed Time Difference Of Arrival)

The OTDOA positioning method utilizes the timing measurements of downlink signals received by the UE from multiple TPs, including the eNB, ng-eNB, and PRS-dedicated TPs. The UE measures the timing of the received downlink signals using location assistance data received from a location server. Based on these measurement results and the geographic coordinates of neighboring TPs, the UE's location can be determined.

A UE connected to a gNB can request a measurement gap for OTDOA measurements from a TP. If the UE does not recognize the SFN for at least one TP in the OTDOA assistance data, the UE can use an autonomous gap to obtain the SFN of the OTDOA reference cell before requesting a measurement gap to perform Reference Signal Time Difference (RSTD) measurements.

Here, the RSTD can be defined based on the smallest relative time difference between the boundaries of two subframes received from the reference cell and the measurement cell, respectively. That is, it can be calculated based on the relative time difference between the start time of the subframe of the reference cell that is closest to the start time of the subframe received from the measurement cell. Meanwhile, the reference cell can be selected by the UE.

Accurate OTDOA measurement requires measuring the time of arrival (TOA) of signals received from three or more geographically dispersed TPs or base stations. For example, the TOA for TP 1, TP 2, and TP 3 can be measured, and based on the three TOAs, the RSTD for TP 1-TP 2, the RSTD for TP 2-TP 3, and the RSTD for TP 3-TP 1 can be calculated. Based on these TOAs, a geometric hyperbola can be determined, and the point where these hyperbolas intersect can be used to estimate the UE's location. Since each TOA measurement may have inaccuracies and/or uncertainties, the estimated UE's location can be known within a certain range depending on the measurement uncertainty.

E-CID (Enhanced Cell ID)

In the Cell ID (CID) positioning method, the location of the UE can be measured through geographic information of the UE's serving ng-eNB, serving gNB, and/or serving cell. For example, geographic information of the serving ng-eNB, serving gNB, and/or serving cell can be obtained through paging, registration, etc.

Meanwhile, the E-CID positioning method may utilize additional UE measurements and/or NG-RAN radio resources in addition to the CID positioning method to improve the UE position estimate. In the E-CID positioning method, some of the same measurement methods as the measurement control system of the RRC protocol may be used, but generally, additional measurements are not performed solely for UE position measurement. In other words, a separate measurement configuration or measurement control message may not be provided to measure the UE's position, and the UE may not expect to be requested to perform additional measurement operations solely for position measurement, and may report measurement values obtained through measurement methods that the UE can generally measure.

For example, a serving gNB can implement an E-CID positioning method using E-UTRA measurements provided from the UE.

AI/ML (Artificial intelligence / machine learning)

Advances in AI/ML technology are leading to the intelligence/advanced development of node(s) and terminal(s) that make up wireless communication networks. In particular, with the intelligence of networks/base stations, it is expected that various network/base station decision parameter values (e.g., transmit/receive power of each base station, transmit power of each terminal, precoder/beam of base station/terminal, time/frequency resource allocation for each terminal, multiplexing (duplexing) method of each base station, etc.) can be quickly optimized and derived/applied according to various environmental parameters (e.g., distribution/location of base stations, distribution/location/material of buildings/furniture, etc., location/movement direction/speed of terminals, climate information, etc.). In line with this trend, many standardization organizations (e.g., 3GPP, O-RAN) are considering its introduction, and research on it is also actively underway.

AI/ML can be easily referred to as artificial intelligence based on deep learning in a narrow sense, but conceptually it is as shown in Figure 8.

- Artificial Intelligence: This can refer to all automation where machines can replace tasks that people would otherwise do.

- Machine Learning: Machines can learn patterns for decision-making from data without explicitly programming rules.

Deep Learning: An AI/ML model based on artificial neural networks. Machines simultaneously extract features from unstructured data and make judgments. The algorithms rely on multilayer networks of interconnected nodes for feature extraction and transformation, inspired by the biological nervous system, or neural networks. Common deep learning network architectures include deep neural networks (DNNs), recurrent neural networks (RNNs), and convolutional neural networks (CNNs).

Classification of AI/ML types based on various criteria

1. Offline vs. Online

(1) Offline Learning: This follows a sequential process of database collection, learning, and prediction. In other words, collection and learning are performed offline, and the completed program can be installed on-site for use in prediction tasks. This offline learning method is used in most situations. In offline learning, the system does not learn incrementally; learning is performed using all available collected data and applied to the system without further training. If learning on new data is required, learning can be restarted using the entire new data set.

(2) Online Learning: Online learning leverages the continuous availability of data available for learning via the Internet. This method incrementally improves performance by learning from additional data. Learning is performed in real time on specific data (sets) collected online, enabling the system to quickly adapt to changing data.

To build an AI system, only online learning may be used, so that learning is performed using only real-time data, or offline learning may be performed using a predetermined data set, and then additional learning may be performed using additional real-time data (online + offline learning).

2. Classification by AI/ML Framework Concept

(1) Centralized Learning: Training data collected from multiple different nodes are reported to a centralized node, and all data resources/storage/learning (e.g., supervised, unsupervised, reinforcement learning) are performed in one central node.

(2) Federated Learning: A collective AI/ML model is built based on data across distributed data owners. Instead of importing data into an AI/ML model, the AI/ML model is imported as a data source, allowing local nodes/individual devices to collect data and train their own copies of the AI/ML model, eliminating the need to report source data to a central node. In federated learning, the parameters/weights of the AI/ML model are simply sent back to the centralized node to support general AI/ML model training. The advantages of federated learning include increased computational speed and superior information security. This eliminates the need to upload personal data to a central server, preventing personal information leaks and misuse.

(3) Distributed Learning: This concept represents the concept of machine learning processes being scaled and distributed across a cluster of nodes. Training AI/ML models are split and shared across multiple nodes operating simultaneously to accelerate AI/ML model training.

3. Classification by learning method

(1) Supervised Learning: Supervised learning is a machine learning task that aims to learn a mapping function from input to output given a labeled data set. The input data is called training data and has known labels or outcomes. Examples of supervised learning include (i) Regression: Linear Regression, Logistic Regression, (ii) Instance-based Algorithms: k-Nearest Neighbor (KNN), (iii) Decision Tree Algorithms: CART, (iv) Support Vector Machines: SVM, (v) Bayesian Algorithms: Naive Bayes, and (vi) Ensemble Algorithms: Extreme Gradient Boosting, Bagging: Random Forest. Supervised learning can be further grouped into regression and classification problems, where classification predicts labels and regression predicts quantities.

(2) Unsupervised Learning: A machine learning task that aims to learn features that explain hidden structures in unlabeled data. The input data is unlabeled and has no known outcome. Some examples of unsupervised learning include K-means clustering, principal component analysis (PCA), nonlinear independent component analysis (ICA), and long-term memory (LSTM).

(3) Reinforcement Learning: In reinforcement learning (RL), an agent interacts with the environment through a trial-and-error process, aiming to optimize a long-term goal. It is a goal-oriented learning method based on interaction with the environment. Examples of RL algorithms include (i) Q-learning, (ii) multi-armed bandit learning, (iii) deep Q network, state-action-reward-state-action (SARSA), (iv) temporal difference learning, (v) actor-critic reinforcement learning, (vi) deep deterministic policy gradient, and (vii) Monte-Carlo tree search. Reinforcement learning can be further grouped into AI/ML model-based reinforcement learning and AI/ML model-free reinforcement learning. Model-based reinforcement learning is an RL algorithm that uses a predictive AI/ML model to obtain transition probabilities between states by using various dynamic states of the environment and the AI/ML model that leads to these states as rewards. Model-free reinforcement learning is a value- or policy-based RL algorithm that maximizes future rewards. It is computationally less complex in multi-agent environments/states and does not require an accurate representation of the environment. RL algorithms can also be categorized into value-based RL versus policy-based RL, and policy-based RL versus non-policy RL.

AI/ML models

Figure 9 illustrates an FFNN (Feed-Forward Neural Network) AI/ML model. Referring to Figure 9, the FFNN AI/ML model includes an input layer, a hidden layer, and an output layer.

Figure 10 illustrates an RNN (Recurrent Neural Network) AI/ML model. Referring to Figure 10, the RNN AI/ML model is a type of artificial neural network in which hidden nodes are connected by directed edges to form a cyclic structure (directed cycle), and is an AI/ML model suitable for processing data that appears sequentially, such as voice and text. One type of RNN is LSTM (Long Short-Term Memory), and LSTM has a structure that adds a cell state to the hidden state of RNN. Specifically, in LSTM, an input gate, a forget gate, an output gate, and a cell state are added to the RNN cell. In Figure 10, A represents a neural network, x _t represents an input value, and h _t represents an output value. Here, h _t can mean a state value representing the present based on time, and h _t-1 can represent a previous state value.

Figure 11 illustrates a CNN (Convolution Neural Network) AI/ML model. CNN uses convolution operations, commonly used in image processing and video processing, to reduce AI/ML model complexity and extract good features. Referring to Figure 11, a kernel or filter refers to a unit/structure that applies weights to inputs within a specific range/unit. The kernel (or filter) can be modified through learning. The stride refers to the range of movement of the kernel within the input. The feature map refers to the result of applying the kernel to the input. Padding refers to a value added to adjust the size of the feature map. Multiple feature maps can be extracted to induce robustness to distortion and changes. Pooling refers to an operation (e.g., max pooling, average pooling) to reduce the size of the feature map by downsampling it.

Figure 12 illustrates an auto-encoder AI/ML model. Referring to Figure 12, an auto-encoder is a neural network that receives a feature vector x as input and outputs the same or similar vector x'. The input and output nodes have the same features, and it is a type of unsupervised learning. Since an auto-encoder reconstructs the input, the output can be referred to as a reconstruction. The loss function can be expressed as in Mathematical Formula 1.

The loss function of the auto encoder exemplified in Figure 12 is calculated based on the difference between the input and the output, and based on this, the degree of loss of the input is identified, and the auto encoder performs an optimization process to minimize the loss.

Figure 13 is a diagram illustrating segmentation AI inference.

Figure 13 illustrates a case where, among split AI operations, the Model Inference function is performed collaboratively by an end device such as a UE and a network AI/ML endpoint.

In addition to the Model Inference function, the Model Training function, Actor, and Data Collection functions can each be split into multiple parts depending on the current task and environment, and performed by multiple entities collaborating.

For example, computationally intensive and energy-intensive parts may be performed at the network endpoint, while privacy-sensitive and latency-sensitive parts may be performed at the end device. In this case, the end device may execute the task/model from input data up to a specific part/layer, and then transmit the intermediated data to the network endpoint. The network endpoint then executes the remaining parts/layers and provides the inference outputs to one or more devices that perform the actions/tasks.

The following describes a functional framework for AI operations.

Below, to explain AI (or AI/ML) more specifically, the terms can be defined as follows.

- Data collection: Data collected from network nodes, management entities, or UEs as a basis for AI model training, data analysis, and inference.

- AI Model: A data-driven algorithm that applies AI technology to generate a set of outputs containing predictive information and/or decision parameters based on a set of inputs.

- AI/ML Training: An online or offline process of training an AI model by learning features and patterns that best represent the data and obtain a trained AI/ML model for inference.

- AI/ML Inference: The process of making predictions or inducing decisions based on collected data and the AI model using a trained AI model.

Referring to FIG. 14, the Data Collection function (10) is a function that collects input data and provides processed input data to the Model Training function (20) and the Model Inference function (30).

Examples of input data may include measurements from UEs or other network entities, feedback from actors, and output from AI models.

The Data Collection function (10) performs data preparation based on input data and provides input data processed through data preparation. Here, the Data Collection function (10) does not perform data preparation specific to each AI algorithm (e.g., data pre-processing and cleaning, formatting, and transformation), but can perform data preparation common to AI algorithms.

After the data preparation process is performed, the Model Training function (10) provides training data (11) to the Model Training function (20) and provides inference data (Inference Data) (12) to the Model Inference function (30). Here, the Training Data (11) is data required as input for the AI Model Training function (20). The Inference Data (12) is data required as input for the AI Model Inference function (30).

The Data Collection function (10) may be performed by a single entity (e.g., UE, RAN node, network node, etc.) or may be performed by multiple entities. In this case, Training Data (11) and Inference Data (12) may be provided to the Model Training function (20) and Model Inference function (30), respectively, from multiple entities.

The Model Training function (20) is a function that performs AI model training, validation, and testing, which can generate model performance metrics as part of the AI model testing process. If necessary, the Model Training function (20) also handles data preparation (e.g., data pre-processing and cleaning, forming, and transformation) based on the Training Data (11) provided by the Data Collection function (10).

Here, Model Deployment/Update (13) is used to initially deploy the trained, verified, and tested AI model to the Model Inference function (30) or to provide the updated model to the Model Inference function (30).

The Model Inference function (30) is a function that provides AI model inference output (16) (e.g., prediction or decision). If applicable, the Model Inference function (30) may provide model performance feedback (14) to the Model Training function (20). In addition, the Model Inference function (30) is also responsible for data preparation (e.g., data pre-processing and cleaning, forming, and transformation) based on the Inference Data (12) provided by the Data Collection function (10), if necessary.

Here, Output (16) refers to the inference output of the AI model generated by the Model Inference function (30), and the details of the inference output may vary depending on the use case.

Model Performance Feedback (14) can be used to monitor the performance of the AI model if available, and this feedback may be omitted.

The actor function (40) is a function that receives the output (16) from the model inference function (30) and triggers or performs a corresponding task/action. The actor function (40) can trigger tasks/actions for other entities (e.g., one or more UEs, one or more RAN nodes, one or more network nodes, etc.) or for itself.

Feedback (15) can be used to derive training data (11), inference data (12), or to monitor the performance of the AI model, its impact on the network, etc.

Meanwhile, the definitions of training/validation/test in the data set used in AI/ML can be distinguished as follows.

- Training data: This refers to the data set for learning the model.

- Validation data: This refers to a data set used to validate a model that has already completed training. In other words, it refers to a data set typically used to prevent overfitting of the training data set.

It also refers to a data set for selecting the best model among the various models learned during the learning process. Therefore, it can be viewed as a type of learning.

- Test data: This refers to the data set for final evaluation. This data is unrelated to learning.

In the case of the above data set, if the training set is generally divided, the training data and validation data can be divided and used in a ratio of 8:2 or 7:3 within the entire training set, and if the test is included, it can be divided and used in a ratio of 6:2:2 (training: validation: test).

Depending on the capability of the AI/ML function between the base station and the terminal, the level of cooperation can be defined as follows, and variations due to combination of multiple levels or separation of any one level are also possible.

Cat 0a) No collaboration framework: AI/ML algorithms are purely implementation-based and do not require any changes to the wireless interface.

Cat 0b) This level corresponds to a framework with a modified wireless interface tailored to efficient implementation-based AI/ML algorithms, but without collaboration.

Category 1) involves inter-node support to improve the AI/ML algorithms of each node. This applies when the UE receives support from the gNB (for training, adaptation, etc.) and vice versa. At this level, model exchange between network nodes is not required.

Category 2) Joint ML tasks can be performed between the UE and gNB. This level requires the exchange of AI/ML model commands or network nodes.

The functions exemplified in FIG. 14 above may be implemented in a RAN node (e.g., a base station, a TRP, a central unit (CU) of a base station, etc.), a network node, an operation administration maintenance (OAM) of a network operator, or a UE.

Alternatively, two or more entities, such as a RAN, a network node, a network operator's OAM, or a UE, may cooperate to implement the functions exemplified in FIG. 14. For example, one entity may perform some of the functions of FIG. 14, and another entity may perform the remaining functions. In this way, since some of the functions exemplified in FIG. 14 are performed by a single entity (e.g., a UE, a RAN node, a network node, etc.), the transmission/provision of data/information between each function may be omitted. For example, if the Model Training function (20) and the Model Inference function (30) are performed by the same entity, the transmission/provision of Model Deployment/Update (13) and Model Performance Feedback (14) may be omitted.

Alternatively, any one of the functions illustrated in FIG. 14 may be performed through collaboration between two or more entities, including a RAN, a network node, a network operator's OAM, or a UE. This may be referred to as a split AI operation.

Figure 15 illustrates a case where the AI Model Training function is performed by a network node (e.g., a core network node, an OAM of a network operator, etc.) and the AI Model Inference function is performed by a RAN node (e.g., a base station, a TRP, a CU of a base station, etc.).

Step 1: RAN node 1 and RAN node 2 transmit input data (i.e., training data) for AI model training to the network node. Here, RAN node 1 and RAN node 2 can also transmit data collected from the UE (e.g., UE measurements related to RSRP, RSRQ, SINR of the serving cell and neighboring cells, UE location, speed, etc.) to the network node.

Step 2: Network nodes train the AI model using the received training data.

Step 3: The network node distributes/updates the AI Model to RAN Node 1 and/or RAN Node 2. RAN Node 1 (and/or RAN Node 2) may continue model training based on the received AI Model.

For convenience of explanation, we assume that the AI Model is deployed/updated only to RAN node 1.

Step 4: RAN node 1 receives input data for AI Model Inference (i.e., Inference data) from UE and RAN node 2.

Step 5: RAN node 1 performs AI Model Inference using the received Inference data to generate output data (e.g., prediction or decision).

Step 6: If applicable, RAN node 1 may transmit model performance feedback to the network nodes.

Step 7: RAN node 1, RAN node 2, and the UE (or 'RAN node 1 and the UE', or 'RAN node 1 and the RAN node 2') perform actions based on the output data. For example, in the case of a load balancing operation, the UE may move from RAN node 1 to RAN node 2.

Step 8: RAN node 1 and RAN node 2 transmit feedback information to the network nodes.

Figure 16 illustrates a case where both the AI Model Training function and the AI Model Inference function are performed by RAN nodes (e.g., base stations, TRPs, CUs of base stations, etc.).

Step 1: UE and RAN node 2 transmit input data (i.e., training data) for AI model training to RAN node 1.

Step 2: RAN node 1 trains the AI model using the received training data.

Step 3: RAN node 1 receives input data for AI Model Inference (i.e., Inference data) from the UE and RAN node 2.

Step 4: RAN node 1 performs AI Model Inference using the received Inference data to generate output data (e.g., prediction or decision).

Step 5: RAN node 1, RAN node 2, and the UE (or 'RAN node 1 and the UE', or 'RAN node 1 and the RAN node 2') perform actions based on the output data. For example, in the case of a load balancing operation, the UE may move from RAN node 1 to RAN node 2.

Step 6: RAN node 2 sends feedback information to RAN node 1.

Figure 17 illustrates a case where the AI Model Training function is performed by a RAN node (e.g., a base station, a TRP, a CU of the base station, etc.) and the AI Model Inference function is performed by a UE.

Step 1: The UE transmits input data (i.e., training data) for AI model training to the RAN node. Here, the RAN node can collect data (e.g., UE measurements related to RSRP, RSRQ, SINR of the serving cell and neighboring cells, UE location, speed, etc.) from various UEs and/or from other RAN nodes.

Step 2: The RAN node trains the AI model using the received training data.

Step 3: The RAN node distributes/updates the AI model to the UE. The UE may also continue model training based on the received AI model.

Step 4: Receive input data (i.e., Inference data) for AI Model Inference from the UE and RAN nodes (and/or from other UEs).

Step 5: The UE performs AI Model Inference using the received Inference data to generate output data (e.g., prediction or decision).

Step 6: If applicable, the UE may send model performance feedback to the RAN node.

Step 7: The UE and RAN nodes perform actions based on the output data.

Step 8: The UE transmits feedback information to the RAN node.

AI/ML based CSI

In the previous NR Rel-18 standardization, research was conducted on CSI compression based on a two-sided AI/ML model and CSI prediction based on a UE-sided model, and FIGS. 18 and 19 illustrate the concepts of CSI compression and CSI prediction, respectively.

In the case of CSI compression illustrated in Fig. 18, the terminal and the base station are each equipped with AI/ML models, and it is a two-sided model (from an inference perspective) that operates as a pair. For convenience, the terminal's model is named AI-encoder and the base station's model is named AI-decoder. The terminal applies the channel information (e.g., raw channel matrix or precoder type channel information vector (e.g., eigenvector)) measured/estimated by itself (which may be preprocessed as necessary) as input to the AI-encoder to generate output, and quantizes the output information and feeds it back to the base station as AI/ML-based CSI. The base station applies the de-quantized information of the fed-back AI/ML-based CSI as input to the AI-decoder to generate output CSI. In this process, the channel information that actually needs to be transmitted is compressed through AI/ML, and the feedback overhead is reduced, so this is called CSI compression.

The CSI prediction illustrated in Figure 19 illustrates a case where an AI/ML model is equipped only on the terminal side to perform inference. The terminal can apply multiple historical measurements as AI/ML inputs and estimate/predict one or more future CSIs as AI/ML model outputs.

Figure 20 is a diagram to explain the concept of the temporal-spatial-frequency (TSF)-CSI compression technique.

The TSF-CSI compression of Fig. 20 can be understood as a combination of the CSI compression and CSI prediction use cases described above. The CSI compression illustrated in Fig. 18 is compression of spatial and frequency domain channel information, and thus can be called SF-CSI compression. TSF-CSI compression applies historical channel information as an additional input to the encoder in SF-CSI compression. Since the network applies historical CSI information decoded in the past network as an additional input to the decoder, it can improve CSI compression performance.

In this way, TSF-CSI compression may have the advantage of increasing the efficiency of estimation and compression for the current channel compared to SF-compression by utilizing past channel information, but it has the following problems/issues.

- Issue 1) When a terminal compresses a CSI report corresponding to a point in time called Slot n+X and feeds it back to the network, if the current CSI at point n+X does not have a good correlation with the past historical CSI (e.g., due to deep fading or a sudden change in the channel environment), problems such as error propagation caused by historical channel information may occur, which may lower the performance of channel estimation/compression.

- Issue 2) Since channel measurement/estimation information for a specific section is continuously buffered, there may be a need for correction/improvement of terminal memory issues or CPU occupancy rules.

- Issue 3) When reporting ground truth CSI for training/monitoring, the feedback overhead can become very large.

Below, we propose solutions primarily for issues 1 and 3.

Proposal 1

For example, for historical CSI information applied as input to the AI-encoder of the terminal and/or historical output CSI information applied to the AI-decoder of the network, the terminal can report information about historical CSI applied to the encoder to the base station.

Historical CSI information reported by a terminal may include some or all of the following:

- Pattern information of historical CSI applied to input (e.g., time/frequency pattern)

- Window size and/or filtering information applied as model input

- Information about channel coherence time

- Information on whether buffer flushing is performed in relation to historical CSI

The pattern of historical CSI may refer to the time/frequency pattern of CSI required to generate information about past CSI that is input to the terminal encoder. Fig. 21 illustrates examples of time/frequency patterns for historical CSI according to one implementation. In Fig. 21, t1-t6 represent time duration/resource (per slot or per multiple slot), and f1-f10 represent frequency resource (e.g., subband) indices. This means that the CSIs corresponding to the shaded time/frequency indices are included as inputs to the AI/ML encoder.

The filtering information may be, for example, information on a filtering method for historical CSI and/or coefficient information of the filter (e.g., weight values for weighted avg), which can also be applied to Proposal 2/3 described below.

The historical window size can refer to, for example, the t1-t6 interval in Fig. 21, and if there is no separate configuration, it can be set/applied as a default value. For example, the default value can be infinity, in which case CSI information that has undergone specific filtering for past historical CSI can be used. Alternatively, if there is no separate configuration for the historical window size, it can be defined as a one-shot measurement, meaning that past historical CSI is not used. The default value setting can be applied equally to the NW side decoder.

When providing data on historical CSI as input to an AI/ML model, multiple (historical) CSIs may have weights applied to them, or a single (historical) CSI value that has been pre-processed (e.g., filtered) may be used as input, and filtering information may include information about this. For example, filtering information may include information about what filtering (e.g., average, weighted average, accumulation, moving average) was used for multiple measured historical CSIs.

Information about a pattern can be reported by the terminal as a 1D/2D bitmap for determining historical CSI in a window. For example, in the case of a 1D bitmap, a historical CSI value calculated based on WB CSI can be used as a bitmap for the time axis. Alternatively, multiple patterns can be preset/defined in a higher layer such as RRC, and a pattern index can be reported to the base station to indicate which pattern has been used by the terminal. This index reporting method has the advantage of reducing payload overhead.

Channel coherence time can refer to the duration during which the terminal channel state does not change significantly. For example, channel coherence time can be calculated based on Equation 2.

In mathematical expression 2, f _m represents the maximum Doppler spread, λ represents the wavelength, and v represents the velocity.

Alternatively, the terminal can measure the channel based on a tracking reference signal (TRS) and transmit a TDCP (time domain channel property) report, which is a report on the correlation measurement value based on the channel measurement, to the base station. For example, the terminal can be configured/defined to perform TSF-compression using only historical CSI existing at the same coherence time as the current CSI of slot n.

In the case of buffer flushing information, for example, if it is determined that there is no correlation with the past historical CSI based on the current CSI of slot n or that it is below a certain level, the terminal may configure new historical CSI or not use historical CSI, which may be advantageous in terms of performance. Therefore, the terminal may delete information related to historical CSI from its memory/buffer and report it to the base station. For example, the terminal may flush information related to historical CSI and calculate CSI using the default CSI information, or use a zero value. When the base station receives buffer flushing information, the base station may also flush information related to historical output CSI and calculate using the default CSI information, or reconstruct the CSI reported by the terminal by reflecting the zero value.

The T/F pattern of historical CSI can be configured to use all of these values as AI/ML model inputs, or the values can be reduced to N (N can be configurable) through the above-described specific filtering and configured as inputs (e.g., inputs as many as the number of f-domains by calculating average or weighted average in time domain). This extension can also apply different filters (coefficients) to each T/F unit (e.g., slot, band).

Meanwhile, as in the above TSF-CSI compression, for historical CSI and/or historical output CSI, one or more inputs of the same input type as the model input (e.g., pre-coder type (e.g., eigenvector), raw channel matrix, channel covariance matrix) related to the current CSI can be input. In this case, since the size of the model input can become very large, in order to achieve the same effect, instead of inputting information of the same type as the model input, time/frequency correlation information for historical CSI based on the current CSI can be used as an additional input. This information can include CSI coherence time and/or CSI correlation (with latest reported CSI)/Doppler spread information, etc. The AI-decoder can configure the input of the AI-decoder using information reported from the terminal, information generated by the base station itself, for example, filtered information (e.g., average, weighted average, accumulation, moving average) for historical output CSI, or correlation information for historical output CSI calculated by the base station.

In this way, TSF-CSI compression uses information such as historical channel information and/or latest reported CSI as input, and if such input information has a good time/frequency correlation for the current channel, performance can be additionally improved based on this. Fig. 22 is a diagram explaining AI/ML-based Differential-CSI compression according to one implementation. Referring to Fig. 22, the terminal can use the differential value between the accumulated CSI and the current measured CSI as AI/ML input. Here, information about the accumulation window for the accumulated CSI can be set by the base station, and the accumulated CSI can be CSI with WB or SB attributes. The terminal can encode the differential value and feed it back to the base station. The NW side can decode the fed-back information, add the differential value to the output CSI accumulated by the NW, and decode/restore the current CSI. Since the terminal only feeds back the differential value, the compression ratio for the feedback information can be improved compared to the existing SF-CSI compression.

Proposal 1 also considers a negotiation process between the terminal and the base station regarding historical (output) CSI patterns. The negotiation process may follow at least one of the following examples, but is not limited thereto.

Example 1: In the base station-initiated method, the base station sets/indicates multiple historical CSI patterns, and the terminal reports information about its selection to the base station. The base station can either use the patterns reported by the terminal as is or signal an ACK message to the terminal.

- Example 2: In the UE-initiated manner, the terminal reports the historical CSI pattern that can be set/applied to the base station, and the base station instructs/sets the terminal with information about the pattern to be applied to the decoder. The terminal can either reflect this as is or report an ACK for confirmation of reception/application to the base station.

- Example 3: If a terminal changes a historical pattern during inference, and requests a change or reports the changed information to the base station, the base station can confirm the report or instruct/set the terminal to indicate that it is not applicable or to provide information on a different pattern.

Proposal 2

(For model monitoring of TSF-CSI compression in Proposal 1) The base station may signal some or all of the following to the terminal for ground truth CSI transmission.

- Pattern information for Historical CSI

- Granularity information of Historical CSI (WB, SB CSI)

- Filtering information for Historical CSI

Proposal 2 addresses issue 3 described above. Historical CSI information can also be applied as AI/ML encoder input. Therefore, terminals can report high-resolution ground truth CSI to the network for multiple historical CSIs (e.g., reports based on the float 32 format or type 2 CSI reports based on high-resolution parameters). In this case, the amount of ground truth CSI reported by the terminal (for training/monitoring purposes in the network) increases with the amount of historical CSI information.

To address this issue, the base station can instruct the terminal to report ground truth CSI only for CSI corresponding to the instructed pattern (e.g., time/frequency pattern) for Proposal 1. Alternatively, the base station can configure or pre-arrange for the terminal to configure historical CSI using only WB CSI, excluding frequency-selective channel characteristics.

Alternatively, the terminal can report a single representative CSI that has undergone filtering (e.g., averaging, accumulation) along with the current CSI as ground truth CSI. In this case, the filtered historical CSI can be WB/SB CSI. WB CSI has the advantage of significantly reducing the reporting payload.

Meanwhile, the quantization granularity/payload for (filtered) historical CSI and current CSI can be applied differently. For example, ground truth CSI for current CSI can be reported with higher payload and higher resolution, while information about (filtered) historical CSI can be reported to the base station with lower resolution and/or payload. For example, while (filtered) historical CSI is quantized to 3 bits/3 bits for amplitude/phase, current CSI can be quantized to 4 bits/4 bits for amplitude/phase, respectively. Instead of (filtered) historical CSI being reported restricted to a specific rank (e.g., rank 1), current CSI can be reported for the full rank or for a number of ranks indicated by the base station. In this way, the base station can set/indicate the ranks to be reported for ground truth CSI.

Proposal 2 can be extended to not only TSF-CSI compression but also CSI prediction based on historical CSI (e.g., Fig. 19).

Proposal 3

For example, when collecting data for model training/inference/monitoring, the following side-information may be reported to the base station along with the collected data for the purpose/classification of the data.

a. Meta information about collected data

- UE mobility information (e.g., location, speed, Doppler info)

- Information about the surrounding environment where data was collected (e.g., site/zone/cell id)

b. Information on whether collected data is labeled

c. Information on whether collected data is omitted

d. Time information of collected data (e.g., time stamp)

Since AI/ML operates in a data-driven manner, model performance can vary depending on data characteristics. Therefore, side information indicating the characteristics of the collected data can be transmitted together. Alternatively, the entity performing the data collection can assign an ID to the data collection and report it.

The subject of the classification of the above data collection (e.g., assigning a dataset ID) may be a terminal, a base station, or a training entity (e.g., OAM, OTT server).

- If the terminal classifies the data collection, the classification list (dataset ID list) is reported to the base station in advance, and if the dataset is reported to the base station based on the data collection procedure, the dataset can be reported together with the ID, etc.

- If the base station classifies the data collection, the terminal can report the Meta information of Proposal 3 for the dataset classification of the base station. Alternatively, the terminal can report to the base station only for the dataset that meets a specific criterion set by the base station (e.g., it can be the value of the dataset's statistic), or if multiple configuration lists are set in advance in the terminal,

The above proposal 3 can be applied not only to the use cases related to the CSI feedback described above, but also to AI/ML model-based operations involving data collection.

The above suggestions 1/2/3 can be applied alone or in combination.

FIG. 23 is a diagram illustrating the operation of a network and a terminal according to at least some of the above-described proposals.

Referring to FIG. 23, a terminal may transmit a UE capability report to the network (2305). The UE capability report may include information about the capabilities of AI/ML models supported by the base station, data collection capabilities, and/or the maximum historic CSI that the terminal can buffer.

The network can signal various configuration information to the terminal (2310). The configuration information may include at least one of configuration information for an AI/ML model, configuration information for a CSI-RS, and/or configuration information for CSI reporting. The configuration information for the AI/ML model may include information about an AI/ML model trained by a base station or training entity.

The terminal can receive an activation instruction for a configured/installed AI/ML model (e.g., TSF-CSI compression, CSI prediction, SF-CSI prediction) from the network (2315).

The terminal receives CSI-RS (2320) and can measure/predict/calculate CSI based on this in an AI/ML model (2325).

The terminal can transmit a CSI report to the network (2330).

The network can decode/restore CSI through an AI/ML model (e.g., decoder) (2335).

The network can schedule DL channels considering CSI and transmit them to the terminal (2340).

The operations in Fig. 23 are exemplary, and some operations may be omitted depending on the embodiment.

Figure 24 illustrates a flow of a method performed by a terminal in a wireless communication system according to one embodiment.

Referring to FIG. 24, the terminal can receive CSI (channel state information) configuration information through upper layer signaling (2405).

The terminal can obtain CSI from an AI/ML (artificial intelligence/machine learning) model based on the CSI configuration information (2410). The data input to the AI/ML model to obtain the CSI may include data on past CSIs calculated prior to the CSI.

The terminal may transmit a CSI report based on the CSI (2415). The CSI report may include information about the time window to which the past CSIs belong in the time domain.

The size of the above time window can be set through the above CSI setting information.

Data on the above past CSIs can be obtained by applying weights to the past CSIs determined within the time window. The CSI report can include information on the weights.

Data on the above past CSIs can be obtained by applying a time-frequency pattern to the past CSIs determined within the time window. The CSI report can include information on the time-frequency pattern.

The above past CSIs can be selected based on the coherency of the channel being maintained for the current point in time.

The terminal may flush its buffer for past CSIs based on the past CSIs being invalid for the current point in time. The terminal may transmit information to the network indicating the flushing of the buffer.

The above CSI report may further include Ground Truth CSI information indicating actual values of the above past CSIs.

The above CSI configuration information may include information on at least one of a pattern, granularity, or filter to be applied to the past CSIs to generate the Ground Truth CSI information.

Figure 25 illustrates a flowchart of a method performed by a base station in a wireless communication system according to one embodiment.

Referring to FIG. 25, the base station can transmit CSI (channel state information) configuration information to the terminal through upper layer signaling (2505).

The base station can receive a CSI report from the terminal based on the CSI setting information (2510).

The base station can reconstruct the CSI calculated in the first AI/ML (artificial intelligence/machine learning) model of the terminal based on the CSI report in the second AI/ML model of the base station (2515).

The data input to the second AI/ML model to reconstruct the CSI may include data on past CSIs calculated prior to the CSI. The CSI report may include information on the time window to which the past CSIs belong in the time domain.

The size of the above time window can be set through the above CSI setting information.

Data on the above past CSIs can be obtained by applying weights to the past CSIs determined within the time window. The CSI report can include information on the weights.

Data on the above past CSIs can be obtained by applying a time-frequency pattern to the past CSIs determined within the time window. The CSI report can include information on the time-frequency pattern.

The above past CSIs can be selected based on the coherency of the channel being maintained for the current point in time.

The terminal may flush the terminal's buffer for past CSIs based on the past CSIs being invalid for the current point in time. The base station may receive information from the terminal indicating the flushing of the buffer.

The above CSI report may further include Ground Truth CSI information indicating actual values of the above past CSIs.

The above CSI configuration information may include information on at least one of a pattern, granularity, or filter to be applied to the past CSIs to generate the Ground Truth CSI information.

Fig. 26 illustrates a communication system (1) applicable to the present disclosure.

Referring to FIG. 26, a communication system (1) includes a wireless device, a base station, and a network. Here, the wireless device refers to a device that performs communication using a wireless access technology (e.g., 5G NR (New RAT), LTE (Long Term Evolution)) and may be referred to as a communication/wireless/5G device. Although not limited thereto, the wireless device may include a robot (100a), a vehicle (100b-1, 100b-2), an XR (eXtended Reality) device (100c), a hand-held device (100d), a home appliance (100e), an IoT (Internet of Things) device (100f), and an AI device/server (400). For example, the vehicle may include a vehicle equipped with a wireless communication function, an autonomous vehicle, a vehicle capable of performing vehicle-to-vehicle communication, etc. Here, the vehicle may include an Unmanned Aerial Vehicle (UAV) (e.g., a drone). XR devices include AR (Augmented Reality)/VR (Virtual Reality)/MR (Mixed Reality) devices, and can be implemented in the form of HMD (Head-Mounted Device), HUD (Head-Up Display) installed in a vehicle, television, smartphone, computer, wearable device, home appliance, digital signage, vehicle, robot, etc. Mobile devices can include smartphone, smart pad, wearable device (e.g., smart watch, smart glass), computer (e.g., laptop, etc.), etc. Home appliances can include TV, refrigerator, washing machine, etc. IoT devices can include sensors, smart meters, etc. For example, base stations and networks can also be implemented as wireless devices, and a specific wireless device (200a) can act as a base station/network node to other wireless devices.

Wireless devices (100a to 100f) can be connected to a network (300) via a base station (200). Artificial Intelligence (AI) technology can be applied to the wireless devices (100a to 100f), and the wireless devices (100a to 100f) can be connected to an AI server (400) via the network (300). The network (300) can be configured using a 3G network, a 4G (e.g., LTE) network, a 5G (e.g., NR) network, etc. The wireless devices (100a to 100f) can communicate with each other via the base station (200)/network (300), but can also communicate directly (e.g., sidelink communication) without going through the base station/network. For example, vehicles (100b-1, 100b-2) can communicate directly (e.g., V2V (Vehicle to Vehicle)/V2X (Vehicle to everything) communication). In addition, IoT devices (e.g., sensors) can communicate directly with other IoT devices (e.g., sensors) or other wireless devices (100a to 100f).

Wireless communication/connection (150a, 150b, 150c) can be established between wireless devices (100a~100f)/base stations (200), and base stations (200)/base stations (200). Here, wireless communication/connection can be achieved through various wireless access technologies (e.g., 5G NR) such as uplink/downlink communication (150a), sidelink communication (150b) (or D2D communication), and base station-to-base station communication (150c) (e.g., relay, IAB (Integrated Access Backhaul). Through wireless communication/connection (150a, 150b, 150c), wireless devices and base stations/wireless devices, and base stations and base stations can transmit/receive wireless signals to each other. For example, wireless communication/connection (150a, 150b, 150c) can transmit/receive signals through various physical channels. To this end, at least some of various configuration information setting processes for transmitting/receiving wireless signals, various signal processing processes (e.g., channel encoding/decoding, modulation/demodulation, resource mapping/demapping, etc.), and resource allocation processes can be performed based on various proposals of the present disclosure.

Figure 27 illustrates a wireless device applicable to the present disclosure.

Referring to FIG. 27, the first wireless device (100) and the second wireless device (200) can transmit and receive wireless signals through various wireless access technologies (e.g., LTE, NR). Here, {the first wireless device (100), the second wireless device (200)} can correspond to {the wireless device (100x), the base station (200)} and/or {the wireless device (100x), the wireless device (100x)} of FIG. 26.

A first wireless device (100) includes one or more processors (102) and one or more memories (104), and may further include one or more transceivers (106) and/or one or more antennas (108). The processor (102) controls the memories (104) and/or the transceivers (106), and may be configured to implement the descriptions, functions, procedures, proposals, methods, and/or operational flowcharts disclosed in this document. For example, the processor (102) may process information in the memory (104) to generate first information/signal, and then transmit a wireless signal including the first information/signal via the transceiver (106). In addition, the processor (102) may receive a wireless signal including second information/signal via the transceiver (106), and then store information obtained from signal processing of the second information/signal in the memory (104). The memory (104) may be connected to the processor (102) and may store various information related to the operation of the processor (102). For example, the memory (104) may perform some or all of the processes controlled by the processor (102), or may store software code including commands for performing the descriptions, functions, procedures, proposals, methods, and/or operation flowcharts disclosed in this document. Here, the processor (102) and the memory (104) may be part of a communication modem/circuit/chip designed to implement a wireless communication technology (e.g., LTE, NR). The transceiver (106) may be connected to the processor (102) and may transmit and/or receive wireless signals via one or more antennas (108). The transceiver (106) may include a transmitter and/or a receiver. The transceiver (106) may be used interchangeably with an RF (Radio Frequency) unit. In the present disclosure, a wireless device may also mean a communication modem/circuit/chip.

The second wireless device (200) includes one or more processors (202), one or more memories (204), and may further include one or more transceivers (206) and/or one or more antennas (208). The processor (202) controls the memories (204) and/or the transceivers (206), and may be configured to implement the descriptions, functions, procedures, proposals, methods, and/or operational flowcharts disclosed in this document. For example, the processor (202) may process information in the memory (204) to generate third information/signals, and then transmit a wireless signal including the third information/signals via the transceivers (206). Furthermore, the processor (202) may receive a wireless signal including fourth information/signals via the transceivers (206), and then store information obtained from signal processing of the fourth information/signals in the memory (204). The memory (204) may be connected to the processor (202) and may store various information related to the operation of the processor (202). For example, the memory (204) may perform some or all of the processes controlled by the processor (202), or may store software code including commands for performing the descriptions, functions, procedures, proposals, methods, and/or operation flowcharts disclosed in this document. Here, the processor (202) and the memory (204) may be part of a communication modem/circuit/chip designed to implement wireless communication technology (e.g., LTE, NR). The transceiver (206) may be connected to the processor (202) and may transmit and/or receive wireless signals via one or more antennas (208). The transceiver (206) may include a transmitter and/or a receiver. The transceiver (206) may be used interchangeably with an RF unit. In the present disclosure, a wireless device may also mean a communication modem/circuit/chip.

Hereinafter, the hardware elements of the wireless device (100, 200) will be described in more detail. Although not limited thereto, one or more protocol layers may be implemented by one or more processors (102, 202). For example, one or more processors (102, 202) may implement one or more layers (e.g., functional layers such as PHY, MAC, RLC, PDCP, RRC, SDAP). One or more processors (102, 202) may generate one or more Protocol Data Units (PDUs) and/or one or more Service Data Units (SDUs) according to the descriptions, functions, procedures, proposals, methods, and/or operation flowcharts disclosed in this document. One or more processors (102, 202) may generate messages, control information, data, or information according to the descriptions, functions, procedures, proposals, methods, and/or operation flowcharts disclosed in this document. One or more processors (102, 202) can generate signals (e.g., baseband signals) including PDUs, SDUs, messages, control information, data or information according to the functions, procedures, proposals and/or methods disclosed herein, and provide the signals to one or more transceivers (106, 206). One or more processors (102, 202) can receive signals (e.g., baseband signals) from one or more transceivers (106, 206) and obtain PDUs, SDUs, messages, control information, data or information according to the descriptions, functions, procedures, proposals, methods and/or operational flowcharts disclosed herein.

One or more processors (102, 202) may be referred to as a controller, a microcontroller, a microprocessor, or a microcomputer. One or more processors (102, 202) may be implemented by hardware, firmware, software, or a combination thereof. For example, one or more Application Specific Integrated Circuits (ASICs), one or more Digital Signal Processors (DSPs), one or more Digital Signal Processing Devices (DSPDs), one or more Programmable Logic Devices (PLDs), or one or more Field Programmable Gate Arrays (FPGAs) may be included in one or more processors (102, 202). The descriptions, functions, procedures, proposals, methods, and/or operational flowcharts disclosed in this document may be implemented using firmware or software, and the firmware or software may be implemented to include modules, procedures, functions, etc. The descriptions, functions, procedures, suggestions, methods and/or operation flowcharts disclosed in this document may be implemented using firmware or software configured to perform one or more processors (102, 202) or stored in one or more memories (104, 204) and executed by one or more processors (102, 202). The descriptions, functions, procedures, suggestions, methods and/or operation flowcharts disclosed in this document may be implemented using firmware or software in the form of codes, instructions and/or sets of instructions.

One or more memories (104, 204) may be coupled to one or more processors (102, 202) and may store various forms of data, signals, messages, information, programs, codes, instructions, and/or commands. The one or more memories (104, 204) may be configured as ROM, RAM, EPROM, flash memory, hard drives, registers, cache memory, computer-readable storage media, and/or combinations thereof. The one or more memories (104, 204) may be located internally and/or externally to the one or more processors (102, 202). Additionally, the one or more memories (104, 204) may be coupled to the one or more processors (102, 202) via various technologies, such as wired or wireless connections.

One or more transceivers (106, 206) can transmit user data, control information, wireless signals/channels, etc., as mentioned in the methods and/or flowcharts of this document, to one or more other devices. One or more transceivers (106, 206) can receive user data, control information, wireless signals/channels, etc., as mentioned in the descriptions, functions, procedures, proposals, methods and/or flowcharts of this document, from one or more other devices. For example, one or more transceivers (106, 206) can be connected to one or more processors (102, 202) and can transmit and receive wireless signals. For example, one or more processors (102, 202) can control one or more transceivers (106, 206) to transmit user data, control information, or wireless signals to one or more other devices. Additionally, one or more processors (102, 202) may control one or more transceivers (106, 206) to receive user data, control information, or wireless signals from one or more other devices. Additionally, one or more transceivers (106, 206) may be coupled to one or more antennas (108, 208), and one or more transceivers (106, 206) may be configured to transmit and receive user data, control information, wireless signals/channels, or the like, as referred to in the descriptions, functions, procedures, proposals, methods, and/or operational flowcharts disclosed herein, via one or more antennas (108, 208). In this document, one or more antennas may be multiple physical antennas or multiple logical antennas (e.g., antenna ports). One or more transceivers (106, 206) may convert received user data, control information, wireless signals/channels, etc. from RF band signals to baseband signals in order to process the received user data, control information, wireless signals/channels, etc. using one or more processors (102, 202). One or more transceivers (106, 206) may convert processed user data, control information, wireless signals/channels, etc. from baseband signals to RF band signals using one or more processors (102, 202). For this purpose, one or more transceivers (106, 206) may include an (analog) oscillator and/or a filter.

Figure 28 illustrates another example of a wireless device applicable to the present disclosure. The wireless device may be implemented in various forms depending on the use case/service (see Figure 26).

Referring to FIG. 28, the wireless device (100, 200) corresponds to the wireless device (100, 200) of FIG. 27 and may be composed of various elements, components, units/units, and/or modules. For example, the wireless device (100, 200) may include a communication unit (110), a control unit (120), a memory unit (130), and an additional element (140). The communication unit may include a communication circuit (112) and a transceiver(s) (114). For example, the communication circuit (112) may include one or more processors (102, 202) and/or one or more memories (104, 204) of FIG. 27. For example, the transceiver(s) (114) may include one or more transceivers (106, 206) and/or one or more antennas (108, 208) of FIG. 27. The control unit (120) is electrically connected to the communication unit (110), the memory unit (130), and the additional elements (140) and controls the overall operation of the wireless device. For example, the control unit (120) may control the electrical/mechanical operation of the wireless device based on the program/code/command/information stored in the memory unit (130). In addition, the control unit (120) may transmit information stored in the memory unit (130) to an external device (e.g., another communication device) via a wireless/wired interface through the communication unit (110), or store information received from an external device (e.g., another communication device) via a wireless/wired interface in the memory unit (130).

The additional element (140) may be configured in various ways depending on the type of the wireless device. For example, the additional element (140) may include at least one of a power unit/battery, an input/output unit (I/O unit), a driving unit, and a computing unit. Although not limited thereto, the wireless device may be implemented in the form of a robot (Fig. 26, 100a), a vehicle (Fig. 26, 100b-1, 100b-2), an XR device (Fig. 26, 100c), a portable device (Fig. 26, 100d), a home appliance (Fig. 26, 100e), an IoT device (Fig. 26, 100f), a digital broadcasting terminal, a hologram device, a public safety device, an MTC device, a medical device, a fintech device (or a financial device), a security device, a climate/environmental device, an AI server/device (Fig. 26, 400), a base station (Fig. 26, 200), a network node, etc. Wireless devices may be mobile or stationary depending on the use/service.

In FIG. 28, various elements, components, units/parts, and/or modules within the wireless device (100, 200) may be entirely interconnected via a wired interface, or at least some may be wirelessly connected via a communication unit (110). For example, within the wireless device (100, 200), the control unit (120) and the communication unit (110) may be wired, and the control unit (120) and a first unit (e.g., 130, 140) may be wirelessly connected via the communication unit (110). In addition, each element, component, unit/part, and/or module within the wireless device (100, 200) may further include one or more elements. For example, the control unit (120) may be composed of one or more processor sets. For example, the control unit (120) may be composed of a set of a communication control processor, an application processor, an electronic control unit (ECU), a graphics processing processor, a memory control processor, etc. As another example, the memory unit (130) may be composed of RAM (Random Access Memory), DRAM (Dynamic RAM), ROM (Read Only Memory), flash memory, volatile memory, non-volatile memory, and/or a combination thereof.

Figure 29 illustrates a vehicle or autonomous vehicle applicable to the present disclosure. The vehicle or autonomous vehicle may be implemented as a mobile robot, a car, a train, a manned or unmanned aerial vehicle (AV), a ship, or the like.

Referring to FIG. 29, a vehicle or autonomous vehicle (100) may include an antenna unit (108), a communication unit (110), a control unit (120), a driving unit (140a), a power supply unit (140b), a sensor unit (140c), and an autonomous driving unit (140d). The antenna unit (108) may be configured as a part of the communication unit (110). Blocks 110/130/140a to 140d correspond to blocks 110/130/140 of FIG. 28, respectively.

The communication unit (110) can transmit and receive signals (e.g., data, control signals, etc.) with external devices such as other vehicles, base stations (e.g., base stations, road side units, etc.), and servers. The control unit (120) can control elements of the vehicle or autonomous vehicle (100) to perform various operations. The control unit (120) can include an ECU (Electronic Control Unit). The drive unit (140a) can drive the vehicle or autonomous vehicle (100) on the ground. The drive unit (140a) can include an engine, a motor, a power train, wheels, brakes, a steering device, etc. The power supply unit (140b) supplies power to the vehicle or autonomous vehicle (100) and can include a wired/wireless charging circuit, a battery, etc. The sensor unit (140c) can obtain vehicle status, surrounding environment information, user information, etc. The sensor unit (140c) may include an IMU (inertial measurement unit) sensor, a collision sensor, a wheel sensor, a speed sensor, an incline sensor, a weight detection sensor, a heading sensor, a position module, a vehicle forward/backward sensor, a battery sensor, a fuel sensor, a tire sensor, a steering sensor, a temperature sensor, a humidity sensor, an ultrasonic sensor, an illuminance sensor, a pedal position sensor, etc. The autonomous driving unit (140d) may implement a technology for maintaining a driving lane, a technology for automatically controlling speed such as adaptive cruise control, a technology for automatically driving along a set path, a technology for automatically setting a path and driving when a destination is set, etc.

For example, the communication unit (110) can receive map data, traffic information data, etc. from an external server. The autonomous driving unit (140d) can generate an autonomous driving route and driving plan based on the acquired data. The control unit (120) can control the drive unit (140a) so that the vehicle or autonomous vehicle (100) moves along the autonomous driving route according to the driving plan (e.g., speed/direction control). During autonomous driving, the communication unit (110) can irregularly/periodically acquire the latest traffic information data from an external server and can acquire surrounding traffic information data from surrounding vehicles. In addition, during autonomous driving, the sensor unit (140c) can acquire vehicle status and surrounding environment information. The autonomous driving unit (140d) can update the autonomous driving route and driving plan based on newly acquired data/information. The communication unit (110) can transmit information regarding the vehicle location, autonomous driving route, driving plan, etc. to the external server. External servers can predict traffic information data in advance using AI technology or other technologies based on information collected from vehicles or autonomous vehicles, and provide the predicted traffic information data to the vehicles or autonomous vehicles.

The embodiments described above are combinations of components and features of the present disclosure in a predetermined form. Each component or feature should be considered optional unless explicitly stated otherwise. Each component or feature may be implemented without being combined with other components or features. Furthermore, it is also possible to form embodiments of the present disclosure by combining some components and/or features. The order of operations described in the embodiments of the present disclosure may be changed. Some components or features of one embodiment may be included in another embodiment or may be replaced with corresponding components or features of another embodiment. It is self-evident that claims that do not have an explicit citation relationship in the patent claims may be combined to form embodiments or incorporated as new claims through post-application amendments.

It will be apparent to those skilled in the art that the present invention can be embodied in other specific forms without departing from the spirit or scope of the invention. Therefore, the above detailed description should not be construed as limiting in any respect, but rather as illustrative. The scope of the present invention should be determined by a reasonable interpretation of the appended claims, and all modifications within the scope of equivalents are intended to be included within the scope of the present invention.

The present disclosure may be used in a terminal, base station, or other equipment of a wireless mobile communication system.

Claims (15)

In a method performed by a terminal, Receive CSI (channel state information) configuration information through upper layer signaling; Obtaining CSI from an AI/ML (artificial intelligence/machine learning) model based on the above CSI setting information; and Including transmitting a CSI report based on the above CSI, The data input to the AI/ML model to obtain the above CSI includes data on past CSIs calculated before the above CSI, A method wherein the above CSI report includes information about the time window to which the past CSIs belong in the time domain. In the first paragraph, A method wherein the size of the above time window is set through the above CSI setting information. In the first paragraph, Data on the above past CSIs are obtained by applying weights to the above past CSIs determined within the above time window, A method wherein the CSI report includes information about the weights. In the first paragraph, Data on the above past CSIs are obtained by applying a time-frequency pattern to the above past CSIs determined within the above time window, A method wherein the CSI report includes information about the time-frequency pattern. In the first paragraph, A method in which the above past CSIs are selected based on the coherency of the channel being maintained for the current point in time. In the first paragraph, A method further comprising flushing a buffer of the terminal for the past CSIs based on the past CSIs being invalid for the current point in time. In paragraph 6, A method further comprising transmitting information to the network notifying flushing of the buffer. In the first paragraph, A method wherein the above CSI report further includes Ground Truth CSI information indicating actual values of the past CSIs. In the first paragraph, A method wherein the CSI configuration information includes information on at least one of a pattern, granularity, or filter to be applied to the past CSIs to generate the Ground Truth CSI information. A non-transitory computer-readable recording medium having recorded thereon a program for performing the method described in claim 1. In the device, a memory configured to store instructions; and A processor configured to perform operations by executing the above instructions, The operations of the above processor are: Receive CSI (channel state information) configuration information through upper layer signaling; Obtaining CSI from an AI/ML (artificial intelligence/machine learning) model based on the above CSI setting information; and Including transmitting a CSI report based on the above CSI, The data input to the AI/ML model to obtain the above CSI includes data on past CSIs calculated before the above CSI, The above CSI report is a device that includes information about the time window to which the past CSIs belong in the time domain. In paragraph 11, Including a transmitter and receiver, The above device is a terminal in a wireless communication system. In paragraph 11, The above device is a processing device configured to control a terminal in a wireless communication system. In a method performed by a base station, Transmit CSI (channel state information) configuration information to the terminal through upper layer signaling; Receiving a CSI report from the terminal based on the above CSI setting information; and Including reconstructing the CSI calculated in the first AI/ML (artificial intelligence/machine learning) model of the terminal based on the CSI report in the second AI/ML model of the base station, The data input to the second AI/ML model to reconstruct the CSI includes data on past CSIs calculated before the CSI, A method wherein the above CSI report includes information about the time window to which the past CSIs belong in the time domain. At the base station, a memory configured to store instructions; and A processor configured to perform operations by executing the above instructions, The operations of the above processor are: Transmit CSI (channel state information) configuration information to the terminal through upper layer signaling; Receiving a CSI report from the terminal based on the above CSI setting information; and Including reconstructing the CSI calculated in the first AI/ML (artificial intelligence/machine learning) model of the terminal based on the CSI report in the second AI/ML model of the base station, The data input to the second AI/ML model to reconstruct the CSI includes data on past CSIs calculated before the CSI, The above CSI report is a base station that includes information about the time window to which the past CSIs belong in the time domain.