Method for base station to receive csi report in wireless communication system and base station

Abstract

Method for a base station to receive a CSI report in a wireless communication system and the base station. The present invention provides a method for a terminal to receive a downlink phase tracking reference signal from a base station in a wireless communication system and an apparatus for supporting the same. According to an embodiment applicable to the present invention, the terminal can receive a phase tracking reference signal from the base station based on the number of phase tracking reference signal ports according to whether transmission configuration indication (TCI) state related information is present in received downlink control information, the number being determined based on different methods. In addition, the base station can transmit a phase tracking reference signal to the terminal accordingly.

Description

[0001] This application is a divisional application of the original invention patent application No. 201980007460.8 (International Application No.: PCT / KR2019 / 000209, Application Date: January 7, 2019, Invention Title: Method and Apparatus for Transmitting and Receiving PT-RS between Terminal Base Stations in a Wireless Communication System). Technical Field

[0002] This disclosure relates to wireless communication systems, and more specifically, to a method for transmitting and receiving downlink phase tracking reference signals (PT-RS) between a terminal and a base station in a wireless communication system, and to apparatus for supporting the method. Background Technology

[0003] Wireless access systems have been widely deployed to provide various types of communication services such as voice and data. Typically, a wireless access system is a multiple access system that supports communication by sharing available system resources (bandwidth, transmit power, etc.) among multiple users. 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).

[0004] The need for significantly improved mobile broadband communications compared to existing radio access technologies (RATs) has increased due to the large number of communication devices requiring higher communication capacity. Furthermore, in next-generation communication systems, large-scale machine-type communications (MTC) capable of providing various services anytime, anywhere by interconnecting multiple devices or objects has been considered. In addition, communication system designs capable of supporting services / UEs sensitive to reliability and latency have been discussed.

[0005] As mentioned above, the introduction of next-generation RATs, taking into account enhanced mobile broadband communications, massive MTC, ultra-reliable and low latency communications (URLLC), etc., has been discussed.

[0006] Specifically, due to the need for methods of transmitting signals in various frequency bands, the concept of a phase tracking reference signal (PT-RS) for estimating the phase noise between a terminal and a base station in various frequency bands is discussed in various ways. Summary of the Invention

[0007] Technical issues

[0008] The purpose of this disclosure is to provide a method for transmitting and receiving downlink phase tracking reference signals (PT-RS) between a terminal and a base station in a wireless communication system, and an apparatus for supporting the method.

[0009] Those skilled in the art will appreciate that the purposes that can be achieved by this disclosure are not limited to those specifically described above, and that the foregoing and other purposes that can be achieved by this disclosure will become clearer from the detailed description below.

[0010] Technical solutions

[0011] This disclosure provides a method for transmitting and receiving downlink phase tracking reference signals (PT-RS) between a terminal (user equipment) and a base station in a wireless communication system, and apparatus for supporting the method.

[0012] In one aspect of this disclosure, a method is provided for a user equipment (UE) to receive PT-RS in a wireless communication system. The method may include the following steps: receiving a physical downlink control channel (PDCCH) including downlink control information (DCI) from a base station; determining, based on a first TCI state or a second TCI state applied to a control resource set (CORESET) for receiving the PDCCH, a number of downlink PT-RS ports scheduled for the UE, depending on whether information related to a first transmit configuration indication (TCI) state exists in the DCI; and receiving the PT-RS from the base station based on the determined number of downlink PT-RS ports.

[0013] When the number of determined downlink PT-RS ports is 1, the UE can receive the PT-RS from one of the DMRS port groups among one or more demodulation reference signal (DMRS) port groups configured for the UE.

[0014] In this case, the number of the one or more DMRS port groups configured for the UE can be equal to the number of reference signal (RS) set information entries included in the first TCI state or the second TCI state.

[0015] When the number of downlink PT-RS ports determined is 1, the UE can receive the PT-RS from one of the multiple DMRS port groups configured for the UE, which is associated with a codeword having a high modulation and coding scheme (MCS) level.

[0016] When the number of downlink PT-RS ports is determined to be 2, the UE can receive the PT-RS from each of the two DMRS port groups configured for the UE.

[0017] In this case, the layer on which the UE receives the PT-RS from each of the DMRS port groups can be determined based on the strongest layer indicator (SLI) associated with each of the DMRS port groups reported by the UE to the base station.

[0018] Therefore, the UE can perform joint coding of SLI associated with the DMRS port group and report the jointly coded SLI to the base station using a broadband report via a Physical Uplink Control Channel (PUCCH) of one or two symbols or a PUCCH of four or more symbols.

[0019] Each of the SLIs associated with the first DMRS port group and the SLIs associated with the second DMRS port group can have a size of two bits.

[0020] The UE can divide each of the SLIs associated with the first DMRS port group and the SLIs associated with the second DMRS port group into Channel State Information (CSI) Part 1 and CSI Part 2, and report CSI Part 1 and CSI Part 2 to the base station using subband reporting via a PUCCH or Physical Uplink Shared Channel (PUSCH) of four or more symbols in length.

[0021] The CSI part 1 may further include a CSI reference signal indicator and a rank indicator, and the CSI part 2 may further include a precoding matrix indicator.

[0022] The SLI associated with the first DMRS port group may have a size of two bits, and the SLI associated with the second DMRS port group may have a variable bit size depending on the rank of the second DMRS port group.

[0023] When the rank of the second DMRS port group is 1, the SLI associated with the second DMRS port group can have a size of zero bits. When the rank of the second DMRS port group is 2, the SLI associated with the second DMRS port group can have a size of one bit. When the rank of the second DMRS port group is 3 or 4, the SLI associated with the second DMRS port group can have a size of two bits.

[0024] In another aspect of this disclosure, a UE is provided for receiving PT-RS in a wireless communication system. The UE may include a receiver and a processor connected to the receiver. The processor may be configured to: receive a PDCCH including a DCI from a base station; determine, based on a first TCI state or a second TCI state applied to a CORESET for receiving the PDCCH, a number of downlink PT-RS ports scheduled for the UE, depending on whether information related to a first TCI state is present in the DCI; and receive the PT-RS from the base station based on the determined number of downlink PT-RS ports.

[0025] In another aspect of this disclosure, a method is provided for a base station to transmit PT-RS to a UE in a wireless communication system. The method may include the steps of: transmitting a PDCCH including a DCI to the UE; and transmitting the PT-RS to the UE. Depending on whether information related to a first TCI state exists in the DCI, the number of downlink PT-RS ports used for transmitting the PT-RS can be determined based on a first TCI state or a second TCI state applied to a CORESET used for transmitting the PDCCH.

[0026] In other aspects of this disclosure, a base station for transmitting PT-RS in a wireless communication system is provided. The base station may include a transmitter and a processor connected to the transmitter. The processor may be configured to transmit a PDCCH including a DCI to the UE; and to transmit the PT-RS to the UE. The number of downlink PT-RS ports for transmitting the PT-RS can be determined based on a first TCI state or a second TCI state applied to a CORESET for transmitting the PDCCH, depending on whether information related to a first TCI state is present in the DCI.

[0027] It should be understood that both the above general description of this disclosure and the following detailed description are exemplary and illustrative, and are intended to provide further explanation of the claimed disclosure.

[0028] Beneficial effects

[0029] As clearly described above, the embodiments of this disclosure have the following effects.

[0030] According to this disclosure, even when the UE cannot receive information about the transmission resources (or beams) for the downlink phase tracking reference signal (PT-RS) in the downlink control information (DCI), the UE can still receive the downlink PT-RS. In other words, the base station can send the downlink PT-RS to the UE without sending information related to the transmission resources (or beams) for the downlink PT-RS in the DCI.

[0031] When a UE is configured with one or more demodulation reference signal (DMRS) port groups, the UE can efficiently report information about the optimal layer for each DMRS port group to the BS in terms of resources. For example, according to this disclosure, when two DMRS port groups are configured, the information about the optimal layer for the second DMRS port group can have a variable bit size based on the rank of the second DMRS port group.

[0032] The effects achievable using the embodiments of this disclosure are not limited to those specifically described above, and those skilled in the art can deduce other effects not described herein based on the following detailed description. In other words, it should be noted that those skilled in the art can deduce effects not anticipated by this disclosure based on the embodiments of this disclosure. Attached Figure Description

[0033] The accompanying drawings, included to provide a further understanding of this disclosure, are provided together with the detailed embodiments to illustrate various embodiments of the disclosure. However, the technical features of this disclosure are not limited to the specific drawings. Features disclosed in each drawing are combined with each other to configure new embodiments. Reference numerals in each drawing correspond to structural elements.

[0034] Figure 1 This is a diagram illustrating a physical channel and a signal transmission method using a physical channel.

[0035] Figure 2 This is a diagram illustrating a self-contained subframe structure applicable to this disclosure.

[0036] Figure 3 and Figure 4 This is a diagram illustrating a representative method of connecting a transceiver unit (TXRU) to an antenna element.

[0037] Figure 5 This is a schematic diagram illustrating a hybrid beamforming structure according to an embodiment of the present disclosure from the perspective of the TXRU and the physical antenna.

[0038] Figure 6 This is a schematic illustration of beam scanning operation for synchronizing signals and system information during downlink (DL) transmission processing according to an embodiment of the present disclosure.

[0039] Figure 7 This is a diagram illustrating a time-domain pattern of a phase tracking reference signal (PT-RS) applicable to this disclosure.

[0040] Figure 8 This is a schematic illustration of two demodulation reference signal (DMRS) configuration types applicable to this disclosure.

[0041] Figure 9 This is a schematic illustration of an example of a first DMRS configuration type applicable to the front-end DMRS of this disclosure.

[0042] Figure 10 This is a schematic illustration of the Channel State Information (CSI) omission rules applicable to this disclosure.

[0043] Figure 11 This is a schematic illustration of a method for transmitting and receiving PT-RS between a base station (BS) and a user equipment (UE) according to an embodiment of the present disclosure. Figure 12 This is a flowchart illustrating a method for a UE to receive PT-RS from a BS according to this disclosure, and Figure 13 This is a flowchart illustrating a method by which a BS sends a PT-RS to a UE according to this disclosure.

[0044] Figure 14 This is a diagram illustrating the configuration of the UE and BS for implementing the proposed implementation. Detailed Implementation

[0045] The embodiments of this disclosure described below are combinations of elements and features of this disclosure in specific forms. Unless otherwise mentioned, these elements or features may be considered optional. Each element or feature may be practiced without combination with other elements or features. Furthermore, embodiments of this disclosure may be constructed by combining portions of elements and / or features. The order of operations described in the embodiments of this disclosure may be rearranged. Some constructions or elements of any embodiment may be included in another embodiment and may be replaced with corresponding constructions or features of another embodiment.

[0046] In the description of the accompanying drawings, detailed descriptions of known processes or steps of this disclosure will be avoided so as not to obscure the subject matter of this disclosure. Furthermore, processes or steps that would be understandable to those skilled in the art will not be described.

[0047] Throughout the specification, when a part “comprises” or “includes” a component, it indicates that no other components are excluded and may be further included, unless otherwise stated. The terms “unit,” “device,” and “module” described in the specification refer to a unit for performing at least one function or operation that can be implemented by hardware, software, or a combination thereof. Additionally, the terms “a,” “an,” “the,” etc., in the context of this disclosure (more specifically, in the context of the appended claims) may include both singular and plural representations, unless otherwise indicated in the specification or unless the context clearly indicates otherwise.

[0048] In the embodiments of this disclosure, the data transmission and reception relationship between the base station (BS) and the user equipment (UE) will be described primarily. The BS refers to a terminal node in the network that communicates directly with the UE. Specific operations described as being performed by the BS can be performed by upper-layer nodes of the BS.

[0049] That is, it is obvious that in a network consisting of multiple network nodes including the BS, various operations performed to communicate with the UE can be performed by the BS or network nodes other than the BS. The term "BS" can be replaced by fixed station, node B, evolved Node B (eNode B or eNB), gNode B (gNB), advanced base station (ABS), access point, etc.

[0050] In embodiments of this disclosure, the term "terminal" can be replaced by UE, mobile station (MS), user station (SS), mobile user station (MSS), mobile terminal, advanced mobile station (AMS), etc.

[0051] The transmitting end can refer to a fixed and / or mobile node that provides data or voice services, while the receiving end can refer to a fixed and / or mobile node that receives data or voice services. Therefore, in uplink (UL) transmission, the UE and BS can act as the transmitting end and the receiving end, respectively. In downlink (DL) transmission, the UE and BS can act as the receiving end and the transmitting end, respectively.

[0052] The embodiments of this disclosure can be supported by at least one publicly disclosed standard specification for radio access systems, including: IEEE 802.xx systems, 3GPP systems, 3GPP Long Term Evolution (LTE) systems, and 3GPP2 systems. In particular, the embodiments of this disclosure can be supported by the standard specifications 3GPP TS 36.211, 3GPP TS 36.212, 3GPP TS 36.213, 3GPP TS 36.321, and 3GPP TS 36.331. That is, steps or parts of the embodiments of this disclosure that are not described in order to clearly reveal the technical ideas of this disclosure can be explained by the above standard specifications. All terms used in the embodiments of this disclosure can be interpreted according to standard specifications.

[0053] Exemplary embodiments of the present disclosure will now be described in detail with reference to the accompanying drawings. The detailed description given below with reference to the drawings is intended to explain exemplary embodiments of the present disclosure, and not to illustrate the only embodiments that can be implemented according to the present disclosure.

[0054] The following detailed description includes specific terminology in order to provide a full understanding of this disclosure. However, it will be apparent to those skilled in the art that specific terms may be substituted with other terms without departing from the spirit and scope of this disclosure.

[0055] The following text describes the 3GPP NR system, which is an example of a radio access system.

[0056] The embodiments disclosed herein can be applied to various wireless access systems such as 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).

[0057] Although embodiments of this disclosure have been described based on the 3GPP NR system in order to illustrate the technical features of this disclosure, this disclosure is also applicable to other radio systems (e.g., 3GPP LTE, IEEE 802.16, IEEE 802.11, etc.).

[0058] 1. NR System

[0059] 1.1. Physical channels and signal transmission and reception methods using them

[0060] In a radio access system, the UE receives information from the BS in the DL and transmits information to the BS in the UL. The information transmitted and received between the UE and the BS includes general data information and various types of control information. Depending on the type / purpose of the information transmitted and received between the UE and the BS, there are many physical channels.

[0061] Figure 1 The physical channel applicable to embodiments of this disclosure and a general signal transmission method using the physical channel are illustrated.

[0062] When the UE is powered on or enters a new cell, the UE performs an initial cell search (S11). The initial cell search involves obtaining synchronization with the BS. Specifically, the UE synchronizes its timing with the BS and obtains information such as the cell identifier (ID) by receiving the primary synchronization channel (P-SCH) and secondary synchronization channel (S-SCH) from the BS.

[0063] Then, the UE can obtain the information broadcast in the cell by receiving the Physical Broadcast Channel (PBCH) from the BS.

[0064] During the initial cell search, the UE can monitor the status of the DL channel by receiving the DL reference signal (RS).

[0065] After completing the initial cell search, the UE can obtain more detailed system information by receiving the Physical Downlink Control Channel (PDCCH) and the Physical Downlink Shared Channel (PDSCH), which depends on the information in the PDCCH (S12).

[0066] To complete access to the BS, the UE can perform a random access procedure (S13 to S16). For this, the UE can transmit a preamble via the Physical Random Access Channel (PRACH) (S13) and receive a Random Access Response (RAR) to the preamble via the PDCCH and the PDSCH associated with the PDCCH (S14). The UE can then transmit the Physical Uplink Shared Channel (PUSCH) based on the scheduling information in the RAR (S15). The UE can perform a contention resolution procedure by receiving the PDCCH signal and the PDSCH signal associated with the PDCCH signal.

[0067] After completing the above process, the UE can perform the reception of PDCCH and / or PDSCH signals (S17) and the transmission of Physical Uplink Control Channel (PUCCH) and PUSCH signals (S18) as a general UL / DL signal transmission process.

[0068] Control information sent from the UE to the BS is usually called uplink control information (UCI). UCI includes hybrid automatic repeat and request-acknowledge / negative-acknowledge (HARQ-ACK / NACK), scheduling request (SR), channel quality indicator (CQI), precoding matrix indicator (PMI), rank indicator (RI), etc.

[0069] Typically, UCIs can be sent periodically via PUCCH in an NR system. However, in some implementations, UCIs can be sent via PUSCH (if control information and service data need to be sent simultaneously). Additionally, the UE can send UCIs intermittently via PUSCH when it receives a request / command from the network.

[0070] 1.2 Parameter Set

[0071] The NR systems to which this disclosure applies support the various sets of Orthogonal Frequency Division Multiplexing (OFDM) parameters shown in the table below. In this case, the cyclic prefix information and the value of μ for each carrier bandwidth portion can be signaled separately in the DL and UL. For example, the cyclic prefix information and the value of μ for each downlink carrier bandwidth portion can be signaled via DL-BWP-mu and DL-MWP-cp corresponding to higher-layer signaling. Similarly, the cyclic prefix information and the value of μ for each uplink carrier bandwidth portion can be signaled via UL-BWP-mu and UL-MWP-cp corresponding to higher-layer signaling.

[0072] [Table 1]

[0073] μ <![CDATA[Δf=2 μ ·15[kHz]]]> Cyclic prefix 0 15 normal 1 30 normal 2 60 Normal, expansion 3 120 normal 4 240 normal

[0074] 1.3 Frame Structure

[0075] DL and UL transmissions are configured with frames of 10ms length. Each frame can consist of ten subframes, each 1ms long. In this case, the number of consecutive OFDM symbols in each subframe is...

[0076] Additionally, each subframe can consist of two half-frames of the same size. In this case, the two half-frames consist of subframes 0 to 4 and subframes 5 to 9, respectively.

[0077] Regarding the subcarrier spacing μ, the time slot can be like... They are numbered in ascending order within a subframe, and can also be... They are numbered in ascending order within a frame. In this case, the number of consecutive OFDM symbols in a time slot can be determined based on the cyclic prefix, as shown in the table below. The start time slot of a subframe In the time dimension, the starting OFDM symbol of the same subframe Alignment. Table 2 shows the number of OFDM symbols in each slot / frame / subframe under the normal cyclic prefix case, and Table 3 shows the number of OFDM symbols in each slot / frame / subframe under the extended cyclic prefix case.

[0078] [Table 2]

[0079]

[0080] [Table 3]

[0081]

[0082] In NR systems to which this disclosure applies, a self-contained time slot structure can be applied based on the above-described time slot structure.

[0083] Figure 2 This is a diagram illustrating a self-contained time slot structure applicable to this disclosure.

[0084] exist Figure 2 In the diagram, shaded areas (e.g., symbol index = 0) indicate downlink control areas, and black areas (e.g., symbol index = 13) indicate uplink control areas. The remaining areas (e.g., symbol indices = 1 to 13) can be used for DL ​​or UL data transmission.

[0085] Based on this structure, the BS and UE can sequentially perform DL and UL transmissions within a single time slot. That is, within a single time slot, the BS and UE can not only send and receive DL data, but also send and receive UL ACK / NACK in response to the DL data. Therefore, due to this structure, the time required for data retransmission in the event of a data transmission error can be reduced, thereby minimizing the waiting time for final data transmission.

[0086] In this self-contained time slot structure, the processes enabling the BS and UE to switch from transmit mode to receive mode and from receive mode to transmit mode require predetermined time slot lengths. Therefore, in the self-contained time slot structure, some OFDM symbols during the switch from DL to UL are set as guard periods (GP).

[0087] Although a self-contained time slot structure is described as including both a DL control region and a UL control region, these control regions can be selectively included in the self-contained time slot structure. In other words, the self-contained time slot structure according to this disclosure can include either a DL control region or a UL control region, or both a DL control region and a UL control region, such as... Figure 2 As shown in the image.

[0088] Additionally, for example, time slots can have various time slot formats. In this case, the OFDM symbols in each time slot can be divided into downlink symbols (represented by "D"), flexible symbols (represented by "X"), and uplink symbols (represented by "U").

[0089] Therefore, the UE can assume that DL transmissions occur only in the symbols represented by "D" and "X" in the DL timeslot. Similarly, the UE can assume that UL transmissions occur only in the symbols represented by "U" and "X" in the UL timeslot.

[0090] 1.4. Simulated Beamforming

[0091] In millimeter-wave (mmW) systems, due to the short wavelength, multiple antenna elements can be installed in the same area. That is, considering a wavelength of 1 cm in the 30 GHz band, a total of 100 antenna elements can be installed in a 5 × 5 cm panel at intervals of 0.5λ (wavelength) in the case of a two-dimensional array. Therefore, in mmW systems, coverage or throughput can be improved by increasing beamforming (BF) gain through the use of multiple antenna elements.

[0092] In this configuration, each antenna port can include a transceiver unit (TXRU) to enable adjustment of transmit power and phase based on the antenna element. By doing so, each antenna element can perform independent beamforming based on frequency resources.

[0093] However, installing TXRUs in all approximately 100 antenna elements is not cost-effective. Therefore, a method has been considered that uses analog phase shifters to map multiple antenna elements to a single TXRU and adjust the beam direction. However, a drawback of this method is that frequency-selective beamforming is impossible because only one beam direction is generated across the entire frequency band.

[0094] To address this issue, a hybrid BF with B TXRUs (Turn-Tube Units) and fewer than Q antenna elements can be considered as an intermediate form between digital and analog BF. In the case of a hybrid BF, the number of beam directions that can be transmitted simultaneously is limited to B or fewer, depending on how the B TXRUs and Q antenna elements are connected.

[0095] Figure 3 and Figure 4 This diagram illustrates a representative connection method for connecting a TXRU to an antenna element. Here, the TXRU virtualization model represents the relationship between the TXRU output signal and the antenna element output signal.

[0096] Figure 3 A method for connecting TXRUs to a subarray is shown. Figure 7In this configuration, an antenna element is connected to a TXRU.

[0097] also, Figure 4 A method for connecting all TXRUs to all antenna elements is shown. Figure 8 In this configuration, all antenna elements are connected to all TXRUs. In this case, a separate additional unit is needed to connect all antenna elements to all TXRUs, such as... Figure 8 As shown in the image.

[0098] exist Figure 3 and Figure 4 In this context, W indicates the phase vector weighted by the analog phase shifter. That is, W is the primary parameter determining the analog beamforming direction. In this case, the mapping relationship between the CSI-RS antenna port and the TXRU can be one-to-one or one-to-many.

[0099] Figure 3 The disadvantage of the configuration shown is that it is difficult to achieve beamforming focusing, but its advantage is that all antennas can be configured at low cost.

[0100] on the contrary, Figure 4 The advantage of the configuration shown is that beamforming and focusing can be easily achieved. However, its disadvantage is high cost, as all antenna elements are connected to the TXRU.

[0101] When multiple antennas are used in the NR system to which this disclosure applies, a hybrid beamforming method can be applied, which combines digital beamforming and analog beamforming. In this case, analog (or radio frequency (RF)) beamforming means performing precoding (or combination) operations at the RF end. In the case of hybrid beamforming, precoding (or combination) is performed at both the baseband end and the RF end. Therefore, the advantage of hybrid beamforming is that it guarantees performance similar to that of digital beamforming while reducing the number of RF chains and the number of D / A (digital-to-analog) (or A / D (analog-to-digital)) converters.

[0102] For ease of description, a hybrid beamforming structure can be represented by N transceiver units (TXRUs) and M physical antennas. In this case, the digital beamforming of the L data layers transmitted by the transmitter can be represented by an N*L (N×L) matrix. Subsequently, the TXRUs convert the N converted digital signals into analog signals, and the analog beamforming, which can be represented by an M*N (M×N) matrix, is applied to the converted signals.

[0103] Figure 5 This is a schematic diagram illustrating a hybrid beamforming structure according to an embodiment of the present disclosure from the perspective of the TXRU and the physical antenna. Figure 5In this context, we assume that the number of digital beams is L and the number of analog beams is N.

[0104] Furthermore, in the NR systems to which this disclosure applies, a method has been considered for providing efficient beamforming to UEs located in a specific area by designing a BS capable of analog beamforming based on symbol changes. Additionally, in the NR systems to which this disclosure applies, a method has been considered for introducing multiple antenna panels that can apply independent hybrid beamforming by defining N TXRUs and M RF antennas as a single antenna panel.

[0105] When the BS uses multiple analog beams as described above, each UE has a different analog beam suitable for signal reception. Therefore, in the NR system to which this disclosure applies, the following beam scanning operation has been considered: the BS applies a different analog beam for each symbol in a specific subframe (SF) (at least relative to synchronization signals, system information, paging, etc.), and then performs signal transmission so that all UEs have a chance to receive the signal.

[0106] Figure 6 This is a schematic illustration of beam scanning operation for synchronizing signals and system information during downlink (DL) transmission processing according to an embodiment of the present disclosure.

[0107] exist Figure 6 In this context, the physical resources (or channels) used to broadcast system information applicable to the NR system of this disclosure are referred to as the physical broadcast channel (xPBCH). In this case, analog beams belonging to different antenna panels can be transmitted simultaneously in a single symbol.

[0108] Additionally, a beam reference signal (BRS) corresponding to the reference signal (RS) of a single analog beam applied (corresponding to a specific antenna panel) has been discussed as a configuration for measuring the channel of each analog beam in the NR system applicable to this disclosure. BRS can be defined for multiple antenna ports, and each BRS antenna port can correspond to a single analog beam. In this case, unlike the BRS, all analog beams in the analog beam group can be applied to the synchronization signal or xPBCH to assist a random UE in correctly receiving the synchronization signal or xPBCH.

[0109] 1.5. PT-RS (Phase Tracking Reference Signal)

[0110] Phase noise will be described below. Jitter that occurs in the time domain may appear as phase noise in the frequency domain. As shown in the following equation, this phase noise randomly alters the phase of the received signal in the time domain.

[0111] [Formula 1]

[0112]

[0113] in

[0114] In Equation 1, the parameter r n ,s n ,d k ,φ n These respectively indicate the received signal, the time-domain signal, the frequency-domain signal, and the phase rotation value caused by phase noise. When the received signal in Equation 1 is processed by DFT (Discrete Fourier Transform), Equation 2 is obtained.

[0115] [Equation 2]

[0116]

[0117] In Equation 2, the parameters These indicate the common phase error (CPE) and inter-cell interference (ICI), respectively. In this case, the value of CPE in Equation 12 increases as the phase noise correlation increases. This CPE can be considered as a carrier frequency offset in the WLAN system, but from the UE's perspective, CPE and CFO can be interpreted as similar to each other.

[0118] By performing CPE / CFO estimation, the UE can eliminate the CPE / CFO corresponding to phase noise in the frequency domain. Furthermore, for correct decoding of the received signal, the UE should perform CPE / CFO estimation before decoding the received signal. Therefore, the BS can send a signal to the UE so that the UE can accurately perform CPE / CFO estimation. That is, the main purpose of this signal is to estimate phase noise. For this purpose, pilot signals previously shared between the BS and the UE can be used, or data signals can be modified or copied. In this specification, the series of signals used for estimating phase noise are generally referred to as Phase Compensation Reference Signal (PCRS), Phase Noise Reference Signal (PNRS), or Phase Tracking Reference Signal (PT-RS). Hereinafter, for ease of description, they will all be referred to as PT-RS.

[0119] 1.5.1. Time-domain plot (or time density)

[0120] Figure 7 This is an illustration of a PT-RS time-domain pattern applicable to this disclosure.

[0121] like Figure 7 As shown, PT-RS can have different patterns depending on the modulation and coding scheme (MCS) level applied.

[0122] [Table 4]

[0123] MCS level PT-RS time pattern (64QAM,CR=1 / 3)<=MCS<(64QAM,CR=1 / 2) #3 (64QAM,CR=1 / 2)<=MCS<(64QAM,CR=5 / 6) #2 (64QAM,CR=5 / 6)<=MCS #1

[0124] like Figure 7 As shown in Table 4, the PT-RS mapping pattern can vary depending on the MCS level applied.

[0125] If this configuration is generalized, the PT-RS time-domain pattern (or time density) can be defined as shown in the table below.

[0126] [Table 5]

[0127] Scheduled MCS <![CDATA[Time density (L PT-RS )]]> <![CDATA[I MCS <ptrs-MCS1]]> PT-RS does not exist <![CDATA[ptrs-MCS1≤I MCS <ptrs-MCS2]]> 4 <![CDATA[ptrs-MCS2≤I MCS <ptrs-MCS3]]> 2 <![CDATA[ptrs-MCS3≤I MCS <ptrs-MCS4]]> 1

[0128] In this case, time densities 1, 2, and 4 can respectively correspond to Figure 7 Patterns #1, #2 and #3.

[0129] In this configuration, ptrs-MCS1, ptrs-MCS2, ptrs-MCS3 and ptrs-MCS4 can be defined via higher-level signaling.

[0130] 1.5.2 Frequency Domain Pattern (or Frequency Density)

[0131] According to this disclosure, PT-RS can be mapped to one subcarrier per resource block (RB), one subcarrier per two RBs, or one subcarrier per four RBs for transmission. In this case, the frequency domain pattern (or frequency density) of the PT-RS can be configured according to the scheduled bandwidth.

[0132] For example, the frequency density can be determined based on the scheduled bandwidth as shown in Table 6.

[0133] [Table 6]

[0134] Scheduled BW Frequency density <![CDATA[0<N RB <=4]]> No PT-RS <![CDATA[5<N RB <=8]]> 1 <![CDATA[9<N RB <=16]]> 1 / 2 <![CDATA[17<N RB <=32]]> 1 / 4

[0135] In this case, frequency density 1 can correspond to the frequency domain pattern of PT-RS being mapped to one subcarrier per RB, frequency density 1 / 2 can correspond to the frequency domain pattern of PT-RS being mapped to one subcarrier per two RBs, and frequency density 1 / 4 can correspond to the frequency domain pattern of PT-RS being mapped to one subcarrier per four RBs.

[0136] If this configuration is generalized, the frequency domain pattern (or frequency density) of the PT-RS can be defined as shown in the table below.

[0137] [Table 7]

[0138] Scheduled bandwidth <![CDATA[Frequency density (K PT-RS )]]> <![CDATA[N RB <N RBO ]]> PT-RS does not exist <![CDATA[N RB0 ≤N RB <N RB1 ]]> 2 <![CDATA[N RB1 ≤N RB ]]> 4

[0139] In this case, frequency density 2 can correspond to the frequency domain pattern in which PT-RS is mapped to one subcarrier for every two RBs, and frequency density 4 can correspond to the frequency domain pattern in which PT-RS is mapped to one subcarrier for every four RBs.

[0140] In this configuration, NRB0 and NRB1 can be defined via higher-level signaling.

[0141] 1.6. DMRS (Demodulation Reference Signal)

[0142] In an NR system to which this disclosure applies, DMRS can be transmitted and received based on a preload structure. Alternatively, in addition to the preload DMRS, supplementary DMRS can also be transmitted and received.

[0143] The preloaded DMRS can support fast decoding. The first OFDM symbol loaded with the preloaded DMRS can be identified as the third (e.g., l=2) or fourth (e.g., l=3) OFDM symbol. The position of the first OFDM symbol can be indicated by the PBCH.

[0144] The number of OFDM symbols occupied by the frontend DMRS can be indicated by a combination of DCI and Radio Resource Control (RRC) signaling.

[0145] Additional DMRS can be configured for high-speed UEs. Additional DMRS can be located in the middle / last (one or more) symbols within a time slot. When one preceding DMRS is configured, additional DMRS can be assigned to zero to three OFDM symbols. When two preceding DMRS are configured, additional DMRS can be assigned to zero or two OFDM symbols.

[0146] The fronthaul DMRS can be configured to have two types. One of the two types can be indicated by higher-level signaling (e.g., RRC signaling).

[0147] Figure 8 The diagram illustrates two DMRS configuration types applicable to this disclosure.

[0148] exist Figure 8 In this context, P0 to P11 can correspond to port numbers 1000 to 1011, respectively. The DMRS configuration type, which is actually configured for the UE, can be indicated by higher-level signaling (e.g., RRC signaling).

[0149] In the case of DMRS configuration type 1, it can be further subdivided according to the number of OFDM symbols allocated for the fronthaul DMRS as follows.

[0150] DMRS configuration type 1 and the number of OFDM symbols allocated for the fronthaul DMRS = 1

[0151] Up to four ports (e.g., P0 to P3) can be multiplexed based on frequency-code division multiplexing (F-CDM) and frequency division multiplexing (FDM) with a length of 2. The RS density can be set to four REs per port in the RB.

[0152] DMRS configuration type 1 and the number of OFDM symbols allocated for the fronthaul DMRS = 2

[0153] Up to eight ports (e.g., P0 to P7) can be multiplexed based on a 2-length F-CDM, a 2-length Time-Code Division Multiple Access (T-CDM), and an FDM. The RS density can be set to 6 REs per port in the RB. When the presence of PT-RS is configured via higher-layer signaling, the T-CDM can be fixed to

[11] . The RS density can be set to 12 REs per port in the RB.

[0154] In the case of DMRS configuration type 2, it can be further subdivided according to the number of OFDM symbols allocated for the front-end DMRS as follows.

[0155] DMRS configuration type 2 and the number of OFDM symbols allocated for the fronthaul DMRS = 1

[0156] Up to six ports (e.g., P0 to P5) can be multiplexed based on F-CDM and FDM of length 2. The RS density can be set to four REs per port in the RB.

[0157] DMRS configuration type 2 and the number of OFDM symbols allocated for the fronthaul DMRS = 2

[0158] Up to 12 ports (e.g., P0 to P11) can be multiplexed based on a 2-length F-CDM, a 2-length T-CDM, and an FDM. The RS density can be set to 6 REs per port in the RB. When the presence of PT-RS is configured via higher-layer signaling, the T-CDM can be fixed to

[11] . The RS density can be set to 8 REs per port in the RB.

[0159] Figure 9 This is a schematic illustration of an example of a first DMRS configuration type applicable to the front-end DMRS of this disclosure.

[0160] Specifically, Figure 9 (a) shows the structure of a DMRS preloaded in a symbol (with a preloaded DMRS of one symbol), and Figure 9 (b) shows the structure of a DMRS preloaded in two symbols (a preloaded DMRS with two symbols).

[0161] exist Figure 9In this context, Δ represents the DMRS offset value in the frequency domain. In this case, DMRS ports with the same Δ value can be code-division multiplexed (CDM-F) in the frequency domain or code-division multiplexed (CDM-T) in the time domain. Alternatively, CDM-F can also be applied to DMRS ports with different Δ values.

[0162] The UE can obtain the DM-RS port configuration information configured by the BS from the DCI.

[0163] 1.7. DMRS Port Group

[0164] In this disclosure, a DMRS port group can refer to a group of DMRS ports in a quasi-co-located (QCL) or partial QCL configuration. Here, quasi-co-located (QCL) may mean that long-term channel parameters such as Doppler spread and / or Doppler shift, average delay, delay spread, etc., are assumed to be the same. Partial QCL may mean that some of the long-term channel parameters are assumed to be the same.

[0165] 1.8. DCI format in NR system

[0166] The NR system to which this disclosure applies can support the following DCI formats. Specifically, the NR system can support DCI format 0_0 and DCI format 0_1 ​​for PUSCH scheduling, and DCI format 1_0 and DCI format 1_1 for PDSCH scheduling. In addition, the NR system can also support DCI format 2_0, DCI format 2_1, DCI format 2_2 and DCI format 2_3 for other purposes.

[0167] DCI format 0_0 can be used to schedule PUSCH based on transmit port (TB) (or TB level), and DCI format 0_1 ​​can be used to schedule PUSCH based on TB (or TB level) or PUSCH based on block group (CBG) (or CBG level) (when CBG-based signal transmission and reception are configured).

[0168] DCI format 1_0 can be used to schedule TB-based (or TB-level) PDSCH, and DCI format 1_1 can be used to schedule TB-based (or TB-level) PDSCH or CBG-based (or CBG-level) PDSCH (when CBG-based signal transmission and reception are configured).

[0169] DCI format 2_0 can be used to notify slot formats. DCI format 2_1 can be used to notify PRB and OFDM symbols when the UE assumes there is no transmission for the UE. DCI format 2_2 can be used to send transmit power control (TPC) commands for PUCCH and PUSCH. DCI format 2_3 can be used to send a set of TPC commands for SRS transmission at one or more UEs.

[0170] Details of the DCI format can be found in 3GPP TS 28.212. That is, features of the DCI format not described in this disclosure can be found in that specification. In addition, definitions of all terms used herein can also be found in that specification.

[0171] 2. Proposed Implementation Methods

[0172] The configuration according to this disclosure will be described in detail below based on the above-described technical features.

[0173] In the NR system to which this disclosure applies, the UE can report a Channel State Information (CSI) report to the BS within a given transmission time (e.g., a time slot) (e.g., CSI Reference Signal Resource Indicator / Rank Indicator (CRI / RI), Channel Quality Indicator (CQI), and / or Precoding Matrix Indicator (PMI)). When the UE transmits a CSI report via a short PUCCH (e.g., a PUCCH consisting of one or two symbols) or transmits a wideband (WB) or partial-band report (e.g., WB or partial-band CSI) via a long PUCCH (e.g., a PUCCH consisting of four or more symbols), the UE can transmit the report by performing joint encoding on the CRI / RI, PMI, CQI, and / or zero-padding bits in a given payload.

[0174] According to this disclosure, when a UE performs a subband (SB) report via a long PUCCH or a CSI report via a PUSCH, the CSI reported by the UE can be divided into two parts as follows.

[0175] Part 1: CQI and CRI / RI of the first codeword (CW)

[0176] Part 2: PMI and CQI of the Second CW

[0177] Figure 10 This is a schematic illustration of the CSI omission rules applicable to this disclosure.

[0178] When the predetermined conditions are met, the UE can, according to this disclosure, be based on Figure 10 The CSI omission rules shown in the example are used to perform CSI omission.

[0179] For example, when the size of the UCI used for CSI reporting at the UE is greater than the size of the resources allocated by the BS to the UE for PUSCH transmission, the UE can use a method based on... Figure 10 The rule illustrated in the example discards the PMI and / or CQI of a specific SB in order to report CSI to the BS.

[0180] For CSI reports on the PUSCH, the CSI Part 2 information bits of a portion of the SB can be omitted. Regarding the priority rules for omitting partial CSI Part 2 information, the priority level (or priority) can decrease from box #0 to box #2N. In this case, the granularity of omission (or the basis for omission) can be... Figure 10 One of the boxes.

[0181] exist Figure 10 In this context, N can represent the number of CSI reports in a time slot, and the CSI report number can correspond to the order in the CSI report configuration.

[0182] According to this disclosure, when the UE performs a CSI report as described above, PT-RS can be configured for the UE via RRC signaling. In this case, the UE can report a Layer Indicator (LI) to the BS as information indicating the optimal layer, to support the BS in determining the DMRS port associated with PT-RS.

[0183] The following section will provide a description of the LI reporting method for the UE applicable to this disclosure.

[0184] When the UE performs a long PUCCH-based SB report or a PUSCH-based CSI report, the LI (Limited Information) that needs to be included in the CSI can always be included in the 1CSI portion related to the WB (or regardless of the UE's reporting characteristics (e.g., whether it's WB / PB or SB)). Additionally, the LI can be encoded separately from other CSI content and then reported to the BS. This is because the 1CSI portion can contain CSI content that is independent of CRI / RI.

[0185] As another example, when the UE performs a CSI report based on a short PUCCH or a WB / PB report based on a long PUCCH, LI can be encoded separately from other CSI content. The decoding order or UCI field order can be determined as CRI->RI->padding bits->(PMI / CQI)->LI, CRI->RI->padding bits->LI->(PMI- / CQI), or CRI->RI->padding bits->PMI->LI->CQI to improve the performance of polarity coding. In this case, depending on the size of RI, the (bit) size of LI can be set to 1 bit (in the case of rank = 2) or 2 bits (in the case of rank > 2).

[0186] As another example, the size of LI can be fixed to a specific size independently of RI. In this case, LI can be encoded together with RI and then reported to BS. The decoding order or UCI field order can be determined as CRI->RI->LI->padding bits->PMI->CQI or CRI->LI->RI->padding bits->PMI->CQI.

[0187] As another example, when the UE performs a long PUCCH-based SB report or a PUSCH-based CSI report, the LI can be configured to always be included in part 1CSI due to the SB characteristics. Therefore, the LI can be encoded separately from other CSI content and then reported to the BS. In this case, joint encoding or individual encoding can be applied to the LI for each SB.

[0188] As another example, when the UE performs a long PUCCH-based SB report or a PUSCH-based CSI report, the LI can be configured to be included in part 2CSI. Therefore, the LI can be encoded separately from other CSI content and then reported to the BS. In this case, the following omission rules can be applied to the CSI.

[0189] 1) In the case of WB CSI reporting, LI can be encoded separately from PMI and CQI used for the second CW. In this case, LI can be mapped to the least significant bit (LSB).

[0190] 2) When LI is configured to have WB capabilities and UE is configured to report SB CSI, UE can communicate with relative to... Figure 10 The omission of priority in the configuration will make LI configured to be included in WB CSI (i.e., the one with the highest priority). Figure 10 The LI is protected from being omitted in the first box of the UE. Then, the UE can report the LI to the BS.

[0191] 3) When the LI is configured with WB capabilities and the UE is configured to report SB CSIs, the entire system can operate without significant problems even if the LI is not reported to the BS. In this case, the LI can be configured to be included in every nth odd-numbered SB CSI report (1 <= n <= N) (see [link to relevant documentation]). Figure 10 Therefore, CSI omission rules can be applied to LI.

[0192] 4) When the LI is configured to have SB characteristics and the UE is configured to report SB CSI, the LI for each SB can be configured to be included in the odd-numbered SB CSI of every nth report. Therefore, CSI omission rules can be applied to the LI.

[0193] 5) Even if the LI is not reported to the BS, the entire system can operate without major problems. For every nth report, the LI can have the lowest priority in CSI omissions. That is, the LI can be configured to have a higher priority than... Figure 10 Odd-numbered SB CSIs have lower priority.

[0194] The following section provides a description of the CSI reporting operation and the related DL PT-RS receiving operation for the UE applicable to this disclosure.

[0195] When two CWs are used in Cyclic Prefix Orthogonal Frequency Division Multiplexing (CP-OFDM) transmission, the UE can report information about the DL layer (e.g., the preferred DL layer) in the CW with the higher CQI to the BS in the UCI. Information about the preferred DL layer can be reported to the BS via LI and used for PT-RS mapping.

[0196] LI can be configured to be separated from other CSIs according to the following encoding rules of WB PMI. The UCI field order can be determined as CRI->RI->padding bits (if present)->PMI->CQI.

[0197] In this disclosure, LI may be referred to as the strongest layer indicator (SLI).

[0198] Hereinafter, the preferred layer group can refer to the layer group preferred by the UE for transmitting feedback signals at each Transmitter-Receiver Point (TRP). The UE's preferred layer group may be equal to or different from the DMRS port group corresponding to each TRP. In this disclosure, it is assumed that the UE's preferred layer group has the same meaning as the DMRS port group described in specifications such as 3GPP TS 38.211, TS 38.212, TS 38.213 and TS 38.214.

[0199] In this disclosure, the number of reported DL PT-RS ports may refer to the number of DL PT-RS ports used by the UE for reporting. Therefore, the number of reported DL PT-RS ports may be equal to or different from the number of DL PT-RS ports configured for the UE.

[0200] However, for ease of description, this disclosure assumes that the number of reported DL PT-RS ports is equal to the number of DL PT-RS ports. Therefore, the reported number of DL PT-RS ports may have the same meaning as the number of DL PT-RS ports.

[0201] Additionally, the number of reported DL PT-RS ports can be equal to the number of SLIs reported by the UE. Although from the perspective of UE behavior, the UE's SLI reports may be unrelated to any DL PT-RS port, the BS can use the UE-reported SLIs to perform mapping between DL PT-RS ports and DMRS ports.

[0202] In this disclosure, the size of the SLI can be determined according to the RI. For example, the SLI size can be configured according to the RI as shown in Table 8 below. When the SLI size changes, the size of the padding bits can also change.

[0203] [Table 8]

[0204] RI Bits used for SLI 1 0 2 1 3 2 4 2

[0205] Although the sizes of CRI and RI are fixed, the sizes of SLI and PMI can be derived / obtained from the values ​​of RI. Therefore, the BS can first calculate the size of the padding bits after decoding CRI and RI, and then improve decoding performance based on this. Afterward, the BS can decode SLI and PMI. For this, SLI needs to be encoded after the padding bits. That is, in this disclosure, the order of UCI fields can be determined as follows.

[0206] CRI->RI->Padding bits (if present)->SLI->PMI->CQI

[0207] Specifically, as mentioned above, the bit size of SLI can vary according to RI. This can be seen from Table 8 above.

[0208] The BS can configure the SLI size for the UE through higher-level signaling (e.g., RRC signaling, Media Access Control-Control Element (MAC-CE) signaling, etc.).

[0209] Because the UCI is a limited resource, the size of the SLI bits included in the UCI is also limited. For example, Table 8 assumes the maximum SLI size is fixed at 2, but in some implementations, the maximum SLI size can be limited to 1. When the maximum SLI size is limited to 1, even in the case of RI = 3 or 4, the SLI size can be set to 1 bit. In this case, the SLI can indicate one of two layers. Here, these two layers are not limited to layers #0 and #1; in some implementations, various combinations such as layers #0 and #2, layers #1 and #3, etc., can be applied.

[0210] In this disclosure, when there is no relevant Transmit Configuration Indicator (TCI) status information in the DCI received from the BS via the PDCCH (e.g., when the higher-layer parameter tci-PresentInDCI is set to "Disabled," i.e., when the higher-layer parameter tci-PresentInDCI is not set to "Enabled"), there may be no relevant TCI status information in the DCI. In this case, the UE can assume that the number of scheduled DL PT-RS ports is the same as the number of DMRS ports.

[0211] The TCI status information sent in the DCI can be used to configure the number of DL PT-RS ports scheduled for the UE. Therefore, when PresentInDCI = "Disabled" (or when there is no TCI status information in the received DCI), the UE can know the number of DL PT-RS ports scheduled.

[0212] Upon receiving a DCI message with PresentInDCI = "Disabled", the UE can expect (assuming) that the number of DL PT-RS ports is the same as the number of DMRS ports.

[0213] When PresentInDCI = "Disabled", multiple DMRS port groups do not need to be defined for the UE. In this case, the number of DMRS port groups can be limited to 1.

[0214] Therefore, upon receiving a DCI with PresentInDCI = "Disabled", the UE can expect (assuming) that the number of DL PT-RS ports is 1.

[0215] Alternatively, upon receiving a DCI with PresentInDCI = "Disabled", the UE can obtain the number of scheduled DL PT-RS ports from the TCI state of the control resource set (CORESET) applied to the current PDCCH reception (or PDCCH carrying DCI).

[0216] Specifically, when there is no TCI state information in the DCI of the CORESET used for scheduling PDSCH, the UE can assume that the TCI state used for PDSCH is equal to the TCI state applied to the CORESET used for PDCCH transmission to determine the QCL information on the PDSCH antenna port.

[0217] After receiving a DCI with PresentInDCI = "Disabled", the UE can obtain the number of DL PT-RS ports from the TCI state applied to the PDCCH carrying the DCI. For example, when the TCI state applied to the PDCCH carrying the DCI includes information about N beam resources (where N = 1 or 2), the UE can identify the number of DL PT-RS ports as N.

[0218] In summary, multiple TCI states can be configured via higher-level signaling (e.g., RRC signaling), and the DCI can indicate a specific TCI state among these multiple TCI states. If a specific TCI state is not provided to the UE via the DCI, the UE can receive the PDSCH based on the TCI state applied to the CORESET used for PDCCH transmission. Additionally, the UE can determine the number of DL PT-RS ports based on the TCI state applied to the CORESET used for PDCCH transmission.

[0219] In other words, when the UE receives a DCI (or PDCCH) with PresentInDCI = "disabled", the UE can perform the following actions.

[0220] When the number of DL PT-RS ports is indicated as 1 by the TCI state applied to CORESET, the UE can expect that only one PT-RS is being sent from one or more DMRS port groups. That is, even if multiple DMRS port groups are configured for the UE, the UE can assume that one DL PT-RS port is scheduled (or configured).

[0221] If the TCI state applied to CORESET includes information about multiple RS sets, the UE can expect to send PT-RS from a DMRS port group in which CW with a high modulation and coding scheme (MCS) is transmitted. In other words, PT-RS can be sent to the UE from one of the multiple DMRS port groups that transmits CW with a high MCS.

[0222] When the number of DL PT-RS ports is indicated as 2 via the TCI state applied to CORESET, the UE can expect to transmit PT-RS from each of the two DMRS port groups. That is, the UE can assume that the number of DL PT-RS ports is 2.

[0223] In this disclosure, the number of DL PT-RS ports can be less than or equal to the number of DMRS port groups. When the number of DL PT-RS ports is equal to the number of DMRS port groups, the UE can report SLI for each DMRS port group (or preferred tier group). On the other hand, when the number of DL PT-RS ports is less than the number of DMRS port groups, the number of SLIs reported by the UE can also be less than the number of DMRS port groups (or preferred tier groups).

[0224] In the prior art, there is no definition of how to determine the number of DL PT-RS ports that will be reported by the UE (or used for reporting). Therefore, this disclosure proposes a method to solve this problem. Hereinafter, the number of DL PT-RS ports used by the UE for reporting may be referred to as the number of reported DL PT-RS ports.

[0225] The UE can anticipate that the number of DL PT-RS ports is less than or equal to the number of preferred layer groups. According to this disclosure, regardless of the number of DL PT-RS ports, the UE can report the SLI for each preferred layer group to the BS. Furthermore, when the number of DL PT-RS ports is less than the number of preferred layer groups in DL data transmission, since the number of preferred layer groups is independent of the number of DL PT-RS ports, there can be no ambiguity between the BS and the UE.

[0226] In this disclosure, the UE can determine the number of DL PT-RS ports defined by TCI or TCI status as the number of reported DL PT-RS ports.

[0227] Specifically, the BS can pre-configure information about the RS set and the number of DL PT-RS ports through a TCI status message to serve the noncoherent joint transmission (JT) operation to the UE. Therefore, the UE can determine the number of DL PT-RS ports as the number of DL PT-RS ports reported.

[0228] In other words, the UE can determine the number of DL PT-RS ports reported from the number of DL PT-RS ports defined by the TCI state associated with the report.

[0229] For example, in the case of non-periodic reporting, the TCI status can be indicated by the DCI that triggers the non-periodic reporting.

[0230] For example, in the case of non-periodic / periodic reporting, TCI status can be pre-configured for the UE.

[0231] In addition, the number of DL PT-RS ports defined by the TCI status can be changed via RRC and / or MAC-CE signaling.

[0232] Therefore, the following implementation methods can be considered.

[0233] When the number of reported DL PT-RS ports is 2 and the number of DMRS port groups (or preferred tier groups) is 2, the UE can determine / select SLI for each DMRS port group (or preferred tier group) and then feed back the corresponding information to the BS.

[0234] When the number of reported DL PT-RS ports is 1, the number of DMRS port groups (or preferred layer groups) is 2, and there is a CW, the UE can determine / select an SLI for all the layers included in all DMRS port groups (or preferred layer groups), and then feed the SLI back to the BS.

[0235] When the number of reported DL PT-RS ports is 1, the number of DMRS port groups (or preferred layer groups) is 2, and there are two CWs, the UE can select an SLI from the CW with the higher CQI and then feed the SLI back to the BS.

[0236] Alternatively, the UE may determine the number of DL PT-RS ports configured by RRC signaling as the number of reported DL PT-RS ports.

[0237] Alternatively, according to this disclosure, the UE may define the number of DL PT-RS ports for reporting based on CSI-ReportConfig reporting settings, CSI-ResourceConfig CSI resource settings, and / or information about measurement configuration.

[0238] In this disclosure, joint encoding or individual encoding can be applied to SLIs corresponding to different DMRS port groups (or preferred layer groups) to feed the SLIs back to the BS. In the case of joint encoding, the bit information of each SLI in the indication feedback bit information can be determined based on the rank of the corresponding DMRS port group (or preferred layer group).

[0239] For example, when the number of DMRS port groups (or preferred layer groups) is 2 and the UE reports the SLI for each group, the jointly coded bit information can be divided into the Most Significant Bit (MSB) and the LSB. Here, the MSB and LSB can respectively indicate the SLI of the first DMRS port group (or preferred layer group) and the SLI of the second DMRS port group (or preferred layer group). The size of each of the MSB and LSB in the feedback bit information can be determined based on the rank of each DMRS port group (or preferred layer group).

[0240] [Table 9]

[0241] RI Bits used for SLI RI Bits used for SLI 1(1,0) 0 5(2,3) 3(1,2) 2(1,1) 0 6(3,3) 4(2,2) 3(1,2) 1(0,1) 7(3,4) 4(2,2) 4(2,2) 2(1,1) 8(4,4) 4(2,2)

[0242] In Table 9 above, RI = X(X1,X2) indicates that the total rank is X, and the ranks of DMRS port groups #1 and #2 (or preferred layer groups #1 and #2) are X1 and X2, respectively.

[0243] In Table 9 above, the bits used for SLI = Y(Y1,Y2) represent a total bit size of Y, and the MSB and LSB sizes are Y1 [bits] and Y2 [bits], respectively.

[0244] When the ranks are given as X1 and X2, X1 and X2 can determine the size of the MSB and LSB, respectively. For example, when X1 = 2 and X2 = 3, the size of the MSB and LSB can be determined such that the MSB = 1 bit (Y1) and the LSB = 2 bits (Y2).

[0245] When the rank is given as X, the ranks X1 and X2 of the DMRS port group (or preferred layer group) can be determined according to the CW-layer mapping rules shown in Table 10 below. For example, when RI = 5, the sizes of MSB and LSB can be determined such that MSB = 1 bit (Y1) and LSB = 2 bits (Y2).

[0246] [Table 10]

[0247] X X1, X2 X X1, X2 1 1，0 5 2，3 2 1，1 6 3，3 3 1，2 7 3，4 4 2，2 8 4，4

[0248] The above implementation method may be efficient for incoherent JTs.

[0249] In the above implementation, when the number of reported DL PT-RS ports is 1, the bits used for SLI can be defined as follows.

[0250] [Table 11]

[0251] RI Bits used for SLI RI Bits used for SLI 1(1,0) 0 5(2,3) 2 2(1,1) 1 6(3,3) 2 3(1,2) 2 7(3,4) 2 4(2,2) 2 8(4,4) 2

[0252] For example, when the rank is 5 or higher, the UE can select the DL layer only within the CW with a higher CQI, and then report the DL layer to the BS. Therefore, the maximum size of the bits used for SLI can be limited to two bits.

[0253] In this case, the bits used for SLI can be interpreted as MSB or LSB.

[0254] According to this disclosure, when one or more SLIs are jointly encoded and transmitted, the bit size of the SLI field (i.e., the bits used for SLI) can be determined by the number of reported DL PT-RS ports and / or RI (i.e., X or {X1,X2}).

[0255] Alternatively, the BS can configure the presence of SLI reports for each DMRS port group (or preferred layer group) for the UE via higher-level signaling (e.g., RRC, MAC-CE, etc.).

[0256] Specifically, each of the various TCI states configured by higher-level signaling can include the presence of an SLI report for each DMRS port group (or preferred tier group). Therefore, the BS can configure the presence of an SLI report for each DMRS port group (or preferred tier group) via higher-level signaling.

[0257] As another example, the presence of SLI reporting can be configured for a UE in accordance with this disclosure via higher-level signaling based on CSI-ReportConfig reporting settings, CSI-ResourceConfig CSI resource settings, and / or information about measurement configuration.

[0258] According to this disclosure, the UE can perform CSI reporting according to the following methods.

[0259] By assuming that two CWs are transmitted from different TRPs / beams, the UE can perform CSI reporting as follows.

[0260] When transmitting a CSI report on a long or short PUCCH using the WB, the UE can perform joint encoding of {SLI for CW#0, SLI for CW#1} and then report the encoding result to the BS. In this case, each of the two SLIs can be fixed at two bits. That is, since the bit size of the SLI is fixed at two bits regardless of the RI, joint encoding can be applied to the RI and SLI.

[0261] When the UE transmits a CSI report on a long PUCCH or PUSCH using the SB, it can report the SLI of CW#0 through CSI part 1 and the SLI of CW#1 through CSI part 2. For example, the CSI reported by the UE can be configured as follows.

[0262] Part 1: {CQI, CRI, RI of CW#0, SLI of CW#0}

[0263] Part 2: {CW#1 CQI, PMI, CW#1 SLI}

[0264] In this case, the bit size of the SLI of CW#0 can be two bits, and the bit size of the SLI of CW#1 can be determined by the rank of CW#1.

[0265] Specifically, when the rank of CW#1 is 1, the bit size of the SLI of CW#1 can be set to 0. In other words, the SLI of CW#1 can be left undefined.

[0266] As another example, when the rank of CW#1 is 2, the bit size of the SLI of CW#1 can be set to 1.

[0267] As another example, when the rank of CW#1 is 3 or 4, the bit size of the SLI of CW#1 can be set to 2.

[0268] Overview

[0269] Figure 11 This is a schematic illustration of a method for transmitting and receiving PT-RS between a BS and a UE according to an embodiment of the present disclosure. Figure 12 This is a flowchart illustrating a method for a UE to receive PT-RS from a BS according to this disclosure, and Figure 13 This is a flowchart illustrating a method by which a BS sends a PT-RS to a UE according to this disclosure.

[0270] The UE receives a PDCCH including DCI from the BS (S1110 and S1210). That is, the BS sends a PDCCH including DCI to the UE (S1110 and S1310).

[0271] DCI can schedule the transmission of PT-RS (and DL data) from the BS to the UE. That is, based on DCI, the UE can identify the scheduled PT-RS (and DL data) sent from the BS.

[0272] The UE can determine the number of PT-RS ports used for receiving PT-RS (S1120 and S1220). In this disclosure, the UE determining the number of PT-RS ports may include determining the number of PT-RS ports by processing at the UE.

[0273] In this scenario, information related to the first TCI state may or may not be present in the DCI. When information related to the first TCI state is present in the DCI, the UE can determine the number of DL PT-RS ports scheduled for the UE based on the first TCI state. When information related to the first TCI state is absent in the DCI, the UE can determine the number of DL PT-RS ports scheduled for the UE based on the second TCI state applied to the CORESET used for receiving the PDCCH including the DCI.

[0274] In this case, the first TCI state may include configuration information about the DMRS port used for DL ​​data scheduled by DCI.

[0275] The UE receives PT-RS (S1130 and S1230) from the BS based on the determined number of DL PT-RS ports.

[0276] That is, the BS sends PT-RS to the UE (S1130 and S1320). As described above, depending on whether there is information related to the first TCI state in the DCI, the number of DL PT-RS ports used for sending PT-RS can be determined based on the first TCI state or the second TCI state applied to the CORESET used for sending PDCCH.

[0277] According to this disclosure, when the number of DL PT-RS ports is determined to be 1, the UE can receive PT-RS from one of the DMRS port groups configured for the UE. In other words, when the determined number of DL PT-RS ports is 1, the UE can receive PT-RS from one of the DMRS port groups configured for the UE.

[0278] The number of one or more DMRS port groups configured for a UE can be equal to the number of RS set information entries included in the first TCI state or the second TCI state.

[0279] According to this disclosure, when the number of DL PT-RS ports is determined to be 1, the UE can receive PT-RS from one of the multiple DMRS port groups configured for the UE that is associated with CW with a high MCS level. In other words, when the determined number of DL PT-RS ports is 1, the UE can receive PT-RS from one of the multiple DMRS port groups configured for the UE that is associated with CW with a high MCS level.

[0280] According to this disclosure, when the number of DL PT-RS ports is determined to be 2, the UE can receive PT-RS from each of the two DMRS port groups configured for the UE. In other words, when the determined number of DL PT-RS ports is 2, the UE can receive PT-RS from each of the two DMRS port groups configured for the UE.

[0281] In this case, the layer on which the UE receives PT-RS from each of the DMRS port groups can be determined based on the SLI associated with each of the DMRS port groups reported by the UE to the BS.

[0282] To this end, the UE can perform joint encoding of the SLI associated with the DMRS port group and report the jointly encoded SLI to the BS via a PUCCH of one or two symbols or a PUCCH of four or more symbols using a WB report. In this case, each of the SLI associated with the first DMRS port group and the SLI associated with the second DMRS port group can be configured to have a size of two bits.

[0283] The UE can divide each of the SLIs associated with the first DMRS port group and the SLIs associated with the second DMRS port group into CSI Part 1 and CSI Part 2, and then report CSI Part 1 and CSI Part 2 to the BS via a PUCCH or PUSCH of four or more symbols using the SB report. CSI Part 1 may also include CRI and RI, and CSI Part 2 may also include PMI. The SLI associated with the first DMRS port group can be configured to have a size of two bits, and the SLI associated with the second DMRS port group can be configured to have a variable bit size depending on the rank of the second DMRS port group.

[0284] Specifically, when the rank of the second DMRS port group is 1, the SLI associated with the second DMRS port group can be configured to have a size of zero bits. When the rank of the second DMRS port group is 2, the SLI associated with the second DMRS port group can be configured to have a size of one bit. When the rank of the second DMRS port group is 3 or 4, the SLI associated with the second DMRS port group can be configured to have a size of two bits.

[0285] Since each implementation of the proposed method can be considered as a method for implementing this disclosure, it is obvious that each implementation can be considered as the proposed method. Furthermore, this disclosure can be implemented not only independently of the proposed methods but also by combining (or merging) some of the proposed methods. Additionally, it is possible to define the following rule: information regarding whether the proposed method is applied (or information regarding rules related to the proposed method) should be sent from the BS to the UE via a predefined signal (e.g., physical layer signal, higher layer signal, etc.).

[0286] 3. Equipment Configuration

[0287] Figure 14 This is a diagram illustrating the configuration of a UE and a BS for implementing the embodiments proposed in this disclosure. Figure 14 The UE and BS illustrated herein operate to implement the above-described implementation of the DL PT-RS transmission and reception method therebetween.

[0288] UE 1 can be used as a transmitter in the UL and as a receiver in the DL. BS (eNB or gNB) 100 can be used as a receiver in the UL and as a transmitter in the DL.

[0289] Each of the UE and BS may include a transmitter (Tx) 10 or 110 and a receiver (Rx) 20 or 120 for transmitting and receiving control information, data and / or messages, as well as an antenna 30 or 130 for transmitting and receiving information, data and / or messages.

[0290] Additionally, each of the UE and BS may include a processor 40 or 140 for implementing the above-described embodiments of this disclosure. The processor 40 or 140 may be configured to control memory 50 or 150, Tx 10 or 110 and / or Rx 20 or 120 to implement the processes and / or methods described / proposed above.

[0291] For example, processor 40 or 140 may include a communication modem designed to implement wireless communication technologies (e.g., LTE, NR, etc.). Memory 50 or 150 may be coupled to processor 40 or 140 and store various information related to the operation of processor 40 or 140. For example, memory 50 or 150 may store software code including instructions for performing all or some of the processes and / or methods described / presented above in the processing controlled by processor 40 or 140. Tx 10 or 110 and / or Rx 20 or 120 may be coupled to processor 40 or 140 and transmit and / or receive radio signals. Processor 40 or 140 and memory 50 or 150 may be part of a processing chip (e.g., a system-on-a-chip (SoC)).

[0292] Using the above configuration, UE 1 can receive the PDCCH, including the DCI, from BS 100 via Rx 20. Depending on whether information related to the first TCI state exists in the DCI, UE 1 can determine the number of DL PT-RS ports scheduled for UE 1 via processor 40 based on the first or second TCI state of the CORESET applied for receiving the PDCCH. UE 1 can then receive PT-RS from BS 100 via Rx 20 based on the determined number of DL PT-RS ports.

[0293] That is, BS 100 can send the PDCCH including DCI to UE 1 via Tx 110, and then send the PT-RS to UE 1 via Tx 110. In this case, depending on whether there is information related to the first TCI state in the DCI, the number of DLPT-RS ports used for sending PT-RS can be determined based on the first TCI state or the second TCI state applied to the CORESET used for sending PDCCH.

[0294] The Tx and Rx of the UE and BS can perform packet modulation / demodulation functions, high-speed packet channel coding functions, OFDMA packet scheduling, TDD packet scheduling and / or channelization for data transmission. Figure 14 Each of the UE and BS may also include a low-power radio frequency (RF) / intermediate frequency (IF) module.

[0295] In addition, the UE can be any of the following: Personal Digital Assistant (PDA), Cellular Phone, Personal Communication Service (PCS) Phone, Global System for Mobile Communications (GSM) Phone, Wideband Code Division Multiple Access (WCDMA) Phone, Mobile Broadband System (MBS) Phone, Handheld PC, Laptop PC, Smartphone, Multi-Mode Multi-Band (MM-MB) Terminal, etc.

[0296] A smartphone is a terminal that combines the advantages of both a mobile phone and a PDA. It integrates the functions of a PDA (i.e., scheduling and data communication such as fax sending and receiving and internet connectivity) into a mobile phone. An MB-MM terminal refers to a terminal with a built-in multi-modem chip that can operate in either mobile internet systems or other mobile communication systems (e.g., CDMA 2000, WCDMA, etc.).

[0297] The embodiments of this disclosure can be implemented by various means (e.g., hardware, firmware, software, or combinations thereof).

[0298] In a hardware configuration, the method according to an exemplary embodiment of this disclosure can be implemented by one or more application-specific integrated circuits (ASICs), digital signal processors (DSPs), digital signal processing devices (DSPDs), programmable logic devices (PLDs), field-programmable gate arrays (FPGAs), processors, controllers, microcontrollers, microprocessors, etc.

[0299] In firmware or software configuration, the method according to embodiments of this disclosure can be implemented as modules, processes, functions, etc., for performing the above-described functions or operations. Software code can be stored in memory 50 or 150 and executed by processor 40 or 140. The memory can be located internally or externally to the processor, and data can be sent to and received from the processor via various known means.

[0300] Those skilled in the art will appreciate that this disclosure may be practiced in other specific ways different from those set forth herein without departing from the spirit and essential characteristics of this disclosure. The above embodiments are therefore to be understood as illustrative in all respects and not restrictive. The scope of this disclosure should be defined by the appended claims and their legal equivalents, rather than by the foregoing description, and all changes falling within the meaning and scope of the appended claims should be included herein. It will be apparent to those skilled in the art that claims not expressly referenced in the appended bundle may be presented as a combination of embodiments of this disclosure, or may be included as new claims by subsequent amendments after filing.

[0301] Industrial applicability

[0302] This disclosure applies to a variety of radio access systems, including 3GPP systems and / or 3GPP2 systems. Beyond these radio access systems, embodiments of this disclosure are applicable to all technical fields where applications can be found in radio access systems. Furthermore, the proposed method can also be applied to millimeter-wave communications using the UHF band.

Claims

1. A method of receiving channel state information (CSI) reports by a base station (BS) in a wireless communication system, the method comprising: receiving CSI reports #1 to #N, where N is a positive integer; and obtaining information bits of the CSI reports #1 to #N, wherein at least one of the CSI reports #1 to #N includes a wideband CSI, and wherein a layer indicator (LI) is included in the wideband CSI of the at least one CSI report. 2.The method of claim 1, wherein omitting a part of the information bits of the CSI reports #1 to #N based on a predefined priority order, starting from a lowest priority level in the predefined priority order, based on a payload size of an uplink channel for the CSI reports. 3.The method of claim 1, wherein each of the CSI reports #1 to #N includes a part 1 CSI, and one or more of the CSI reports #1 to #N includes a part 2 CSI. 4.The method of claim 3, wherein, the LI is included in the part 2 CSI of at least one of the CSI reports including the wideband CSI. 5.The method of claim 3, wherein omitting a part of the information bits of the CSI reports #1 to #N based on a predefined priority order, and wherein, in the predefined priority order, a wideband CSI for the part 2 CSI of the CSI reports #1 to #N has a higher priority level than each subband CSI of the part 2 CSI. 6.The method of claim 3, wherein the part 2 CSI includes at least a precoding matrix indicator (PMI) or a channel quality indicator (CQI) for a second codeword. 7.The method of claim 6, wherein the LI is encoded separately from the PMI or the CQI for the second codeword. 8.A base station (BS) in a wireless communication system, the BS comprising: at least one transceiver; at least one processor; and at least one computer memory operably connectable to the at least one processor and storing instructions that, when executed, cause the at least one processor to perform the following operations: receiving CSI reports #1 to #N, where N is a positive integer; and obtaining information bits of the CSI reports #1 to #N, wherein at least one of the CSI reports #1 to #N includes a wideband CSI, and wherein a layer indicator (LI) is included in the wideband CSI of the at least one CSI report. 9.The BS of claim 8, wherein omitting a part of the information bits of the CSI reports #1 to #N based on a predefined priority order, starting from a lowest priority level in the predefined priority order, based on a payload size of an uplink channel for the CSI reports. 10.The BS of claim 8, wherein, Each of the CSI reports #1 to #N includes partial 1 CSI, and one or more of the CSI reports #1 to #N includes partial 2 CSI.

11. The BS of claim 10, wherein The LI is included in the partial 2 CSI of at least one of the CSI reports including the wideband CSI.

12. The BS of claim 10, wherein A portion of the information bits of the CSI reports #1 to #N is omitted based on a predefined priority order, and wherein, in the predefined priority order, wideband CSI for the partial 2 CSI of the CSI reports #1 to #N has a higher priority level than each subband CSI of the partial 2 CSI.

13. The BS of claim 10, wherein The partial 2 CSI includes at least a precoding matrix indicator (PMI) or a channel quality indicator (CQI) for a second codeword.

14. The BS of claim 13, wherein The LI is encoded separately from the PMI or the CQI for the second codeword.

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