KR20240040572A - Method and apparatus for receiving ptrs in wireless communication system - Google Patents

Abstract

This disclosure describes methods and devices for a terminal or base station to receive a phase tracking reference signal (PTRS) in a wireless communication system. In particular, a method for a terminal to receive a PTRS in a wireless communication system according to various embodiments of the present disclosure performs linear interpolation based on two resource elements (REs) to which a demodulation reference signal (DMRS) is assigned. By doing so, obtaining a first CFR estimate in the RE to which the PTRS is assigned, calculating an estimate of the CPE angle difference for the RE to which the PTRS is assigned, and adding the estimate of the CPE angle difference to the first CFR estimate. It may include performing phase tracking of the RE to which the PTRS is assigned based on the second CFR estimate obtained by applying it.
In addition to this, various embodiments identified through the specification are possible.

Description

Method and apparatus for receiving PTRS in a wireless communication system {METHOD AND APPARATUS FOR RECEIVING PTRS IN WIRELESS COMMUNICATION SYSTEM}

This disclosure relates to wireless communication systems, and more specifically to a method and apparatus for receiving PTRS for phase noise estimation in a wireless communication system.

5G mobile communication technology defines a wide frequency band to enable fast transmission speeds and new services, and includes sub-6 GHz ('Sub 6GHz') bands such as 3.5 gigahertz (3.5 GHz) as well as millimeter wave (mm) bands such as 28 GHz and 39 GHz. It is also possible to implement it in the ultra-high frequency band ('Above 6GHz') called Wave. In addition, in the case of 6G mobile communication technology, which is called the system of Beyond 5G, Terra is working to achieve a transmission speed that is 50 times faster than 5G mobile communication technology and an ultra-low delay time that is reduced to one-tenth. Implementation in Terahertz (THz) bands (e.g., 3 terahertz bands at 95 GHz) is being considered.

In the early days of 5G mobile communication technology, there were concerns about ultra-wideband services (enhanced Mobile BroadBand, eMBB), ultra-reliable low-latency communications (URLLC), and massive machine-type communications (mMTC). With the goal of satisfying service support and performance requirements, efficient use of ultra-high frequency resources, including beamforming and massive array multiple input/output (Massive MIMO) to alleviate radio wave path loss in ultra-high frequency bands and increase radio transmission distance. Various numerology support (multiple subcarrier interval operation, etc.) and dynamic operation of slot format, initial access technology to support multi-beam transmission and broadband, definition and operation of BWP (Band-Width Part), large capacity New channel coding methods such as LDPC (Low Density Parity Check) codes for data transmission and Polar Code for highly reliable transmission of control information, L2 pre-processing, and dedicated services specialized for specific services. Standardization of network slicing, etc., which provides networks, has been carried out.

Currently, discussions are underway to improve and enhance the initial 5G mobile communication technology, considering the services that 5G mobile communication technology was intended to support, based on the vehicle's own location and status information. V2X (Vehicle-to-Everything) to help autonomous vehicles make driving decisions and increase user convenience, and NR-U (New Radio Unlicensed), which aims to operate a system that meets various regulatory requirements in unlicensed bands. ), NR terminal low power consumption technology (UE Power Saving), Non-Terrestrial Network (NTN), which is direct terminal-satellite communication to secure coverage in areas where communication with the terrestrial network is impossible, positioning, etc. Physical layer standardization for technology is in progress.

In addition, IAB (IAB) provides a node for expanding the network service area by integrating intelligent factories (Industrial Internet of Things, IIoT) to support new services through linkage and convergence with other industries, and wireless backhaul links and access links. Integrated Access and Backhaul, Mobility Enhancement including Conditional Handover and DAPS (Dual Active Protocol Stack) handover, and 2-step Random Access (2-step RACH for simplification of random access procedures) Standardization in the field of wireless interface architecture/protocol for technologies such as NR) is also in progress, and a 5G baseline for incorporating Network Functions Virtualization (NFV) and Software-Defined Networking (SDN) technology Standardization in the field of system architecture/services for architecture (e.g., Service based Architecture, Service based Interface) and Mobile Edge Computing (MEC), which provides services based on the location of the terminal, is also in progress.

When this 5G mobile communication system is commercialized, an explosive increase in connected devices will be connected to the communication network. Accordingly, it is expected that strengthening the functions and performance of the 5G mobile communication system and integrated operation of connected devices will be necessary. To this end, eXtended Reality (XR) and Artificial Intelligence are designed to efficiently support Augmented Reality (AR), Virtual Reality (VR), and Mixed Reality (MR). , AI) and machine learning (ML), new research will be conducted on 5G performance improvement and complexity reduction, AI service support, metaverse service support, and drone communication.

In addition, the development of these 5G mobile communication systems includes new waveforms, full dimensional MIMO (FD-MIMO), and array antennas to ensure coverage in the terahertz band of 6G mobile communication technology. , multi-antenna transmission technology such as Large Scale Antenna, metamaterial-based lens and antenna to improve coverage of terahertz band signals, high-dimensional spatial multiplexing technology using OAM (Orbital Angular Momentum), RIS ( In addition to Reconfigurable Intelligent Surface technology, Full Duplex technology, satellite, and AI (Artificial Intelligence) to improve the frequency efficiency of 6G mobile communication technology and system network are utilized from the design stage and end-to-end. -to-End) Development of AI-based communication technology that realizes system optimization by internalizing AI support functions, and next-generation distributed computing technology that realizes services of complexity beyond the limits of terminal computing capabilities by utilizing ultra-high-performance communication and computing resources. It could be the basis for .

To enable compensation for phase noise that may occur during signal transmission and reception, a phase tracking reference signal (PTRS) was introduced into new radio (NR). Generally, phase noise increases as a function of oscillator carrier frequency. The degradation due to phase noise in orthogonal frequency division multiplexing (OFDM) signals is the equal phase rotation of all subcarriers, known as common phase error (CPE). PTRS can be used at high carrier frequencies (e.g., frequency range 2 (FR2) where millimeter wave or mmWave is used) to mitigate phase noise.

Because the phase rotation produced by CPE is the same for all subcarriers within an OFDM symbol, PTRS is less dense in the frequency domain and more dense in the time domain. PTRS is UE device specific, limited to scheduled resource blocks (RBs), and can be beamformed. The number of PTRS ports may be less than the total number of demodulation reference signal (DMRS) ports, and orthogonality between PTRS ports is achieved by FDM. PTRS can be configured according to the quality of the oscillator, allocated bandwidth (BW), carrier frequency, OFDM subcarrier spacing, and modulation and coding methods used for transmission.

Recently, with the development of wireless communication systems, research on ways to utilize PTRS in next-generation communication systems is being actively conducted. Accordingly, the demand for channel estimation technology using radio resources allocated to PTRS is increasing.

Various embodiments disclosed in this document provide a method and apparatus for receiving PTRS to estimate phase noise in a wireless communication system.

According to various embodiments disclosed in this document, a method for a terminal to receive a phase tracking reference signal (PTRS) in a wireless communication system is linearly based on two resource elements (REs) to which a demodulation reference signal (DMRS) is assigned. Obtaining a first CFR estimate in the RE to which the PTRS is assigned by performing interpolation (linear interpolation); calculating an estimate of the CPE angle difference for the RE to which the PTRS is assigned; It may include performing phase tracking of the RE to which the PTRS is assigned based on a second CFR estimate obtained by applying the estimate of the CPE angle difference.

According to various embodiments disclosed in this document, a terminal that receives a phase tracking reference signal (PTRS) in a wireless communication system includes a transceiver and at least one processor, and the at least one processor includes a demodulation reference signal (DMRS). ) By performing linear interpolation based on the two REs (resource elements) to which the PTRS is assigned, a first CFR estimate is obtained in the RE to which the PTRS is assigned, and the CPE angle for the RE to which the PTRS is assigned is obtained. Calculate an estimate of the difference, and based on a second CFR estimate obtained by applying the estimate of the CPE angle difference to the first CFR estimate, the PTRS will be set to perform phase tracking of the assigned RE. You can.

According to various embodiments disclosed in this document, a method for a base station to receive a phase tracking reference signal (PTRS) in a wireless communication system is linearly based on two resource elements (REs) to which a demodulation reference signal (DMRS) is assigned. Obtaining a first CFR estimate in the RE to which the PTRS is assigned by performing interpolation (linear interpolation), calculating an estimate of the CPE angle difference for the RE to which the PTRS is assigned, It may include performing phase tracking of the RE to which the PTRS is assigned based on a second CFR estimate obtained by applying the estimate of the CPE angle difference.

According to various embodiments disclosed in this document, a base station that receives a phase tracking reference signal (PTRS) in a wireless communication system includes a transceiver and at least one processor, and the at least one processor includes a demodulation reference signal (DMRS). ) By performing linear interpolation based on the two REs (resource elements) to which the PTRS is assigned, the first CFR estimate in the RE to which the PTRS is assigned is obtained, and the CPE angle for the RE to which the PTRS is assigned is obtained. Calculate an estimate of the difference, and based on a second CFR estimate obtained by applying the estimate of the CPE angle difference to the first CFR estimate, the PTRS will be set to perform phase tracking of the assigned RE. You can.

FIG. 1 illustrates resource elements (REs) to which a phase tracking reference signal (PTRS) is assigned in a wireless communication system according to various embodiments of the present disclosure.
2 illustrates common phase error (CPE) according to various embodiments of the present disclosure.
3 illustrates channel frequency response (CFR) according to various embodiments of the present disclosure.
FIG. 4 illustrates OFDM symbols on a specific subcarrier according to various embodiments of the present disclosure on the time axis.
Figure 5 illustrates a channel estimation operation of a terminal according to various embodiments of the present disclosure.
Figure 6 illustrates a channel estimation operation of a terminal according to various embodiments of the present disclosure.
Figure 7 illustrates a channel estimation operation of a terminal according to various embodiments of the present disclosure.
Figure 8 illustrates a channel estimation operation of a terminal according to various embodiments of the present disclosure.
Figure 9 shows a graph of block error rate (BLER) versus signal to noise ratio (SNR) according to various embodiments of the present disclosure.
Figure 10 shows a BLER versus SNR graph according to various embodiments of the present disclosure.
Figure 11 shows the structure of a terminal according to various embodiments of the present disclosure.
Figure 12 shows the structure of a base station according to various embodiments of the present disclosure.
In relation to the description of the drawings, identical or similar reference numerals may be used for identical or similar components.

Various aspects of claimed subject matter are described with reference to the drawings, in which like reference numerals are used to refer to like elements. In the following description, for purposes of explanation, numerous specific details are set forth to provide a thorough understanding of one or more embodiments. However, it may be clear that the embodiment(s) may be practiced without these specific details.

Terms used in the present disclosure are merely used to describe specific embodiments and may not be intended to limit the scope of other embodiments. Singular expressions may include plural expressions, unless the context clearly dictates otherwise. Terms used herein, including technical or scientific terms, may have the same meaning as generally understood by a person of ordinary skill in the technical field described in this disclosure. Among the terms used in this disclosure, terms defined in general dictionaries may be interpreted to have the same or similar meaning as the meaning they have in the context of related technology, and unless clearly defined in this disclosure, have an ideal or excessively formal meaning. It is not interpreted as In some cases, even terms defined in the present disclosure cannot be interpreted to exclude embodiments of the present disclosure.

Terms referring to signals used in the following description (e.g. message, signal, signaling, sequence, stream), terms referring to resources (e.g. symbol, slot) , subframe, radio frame, subcarrier, RE (resource element), RB (resource block), BWP (bandwidth part), opportunity (Occasion), for operation Terms referring to data (e.g. step, method, process, procedure), terms referring to data (e.g. information, parameter, variable, value ( value, bit, symbol, codeword), terms referring to channels, terms referring to control information (e.g. downlink control information (DCI), medium access control code word (MAC CE) Element), RRC (radio resource control (RRC) signaling), terms referring to network entities, terms referring to device components, etc. are exemplified for convenience of explanation. Accordingly, the present disclosure is not limited to the terms described below, and other terms having equivalent technical meaning may be used.

Various embodiments are described herein with respect to a wireless terminal and/or base station. A wireless terminal may refer to a device that provides voice and/or data connectivity to a user. The wireless terminal may be connected to a computing device, such as a laptop computer or desktop computer, or may be a self-contained device such as a personal digital assistant (PDA). A wireless terminal may also be called a system, subscriber unit, subscriber station, mobile station, mobile, mobile device, remote station, remote terminal, access terminal, user terminal, terminal, wireless communication device, user agent, user device, or user equipment. . A wireless terminal is a subscriber station, wireless device, cellular telephone, PCS telephone, cordless telephone, Session Initiation Protocol (SIP) telephone, wireless local loop (WLL) station, personal digital assistant (PDA), portable device with wireless connectivity capability, or It could be any other processing device connected to the wireless modem. A base station (eg, access point) may refer to a device in an access network that communicates with wireless terminals over one or more sectors over a wireless interface. A base station may encompass an Internet Protocol (IP) network and act as a router between wireless terminals and the rest of the access network by converting received air interface frames into IP packets. The base station also coordinates management of attributes for the air interface.

Terms used in this document are merely used to describe specific embodiments and may not be intended to limit the scope of other embodiments. Singular expressions may include plural expressions, unless the context clearly indicates otherwise. All terms used herein, including technical or scientific terms, may have the same meaning as commonly understood by a person of ordinary skill in the technical field of the present disclosure. Terms defined in commonly used dictionaries can be interpreted as having the same or similar meaning as the meaning they have in the context of related technology, and unless clearly defined in this document, they are not interpreted in an ideal or excessively formal sense. . In some cases, even terms defined in this document cannot be interpreted to exclude embodiments of the present disclosure.

Orthogonal Frequency-division Multiplexing (OFDM)-based wireless communication systems use a reference signal in the frequency domain to estimate phase error, which commonly affects all OFDM subcarriers. (common phase error, CPE) must be estimated and compensated. Additionally, the influence of inter-carrier interference (ICI) can be reduced by estimating and compensating for phase error on a symbol basis using cyclic prefix (CP) in the time domain.

In the 3rd generation partnership project (3GPP) long term evolution (LTE) and new radio (NR) systems, DMRS (Demodulation Reference Signal) can be inserted in the time domain and frequency domain. DMRS can be inserted by skipping one or multiple OFDM symbols in the time domain. Assuming that the wireless channel does not change, channel estimation can be performed by performing linear interpolation or extrapolation on OFDM symbols in which DMRS is inserted nearby to estimate the channel of the OFDM symbol in which DMRS is not inserted. .

In 3GPP, the frequency band 24.25 GHz to 52.6 GHz region is defined as FR (Frequency Range) 2. When 5G communication is performed using a frequency corresponding to FR 2, large phase noise (PN) may occur mainly on the terminal side rather than the base station. At this time, even if the wireless channel does not change, channels between different OFDM symbols at the receiving end may appear different due to phase noise. Additionally, in channels that change slowly over time, the channel in OFDM without a DMRS can be estimated by linear interpolation or extrapolation of the channel in OFDM with a surrounding DMRS. However, due to phase noise, the linear A characteristic may no longer be valid. Therefore, PTRS can be inserted so that the receiver can perform channel estimation more accurately in OFDM symbols where DMRS does not exist. PTRS is a training signal for estimating and compensating for phase distortion due to phase noise, Doppler effect, or synchronization error.

1 illustrates resource elements (REs) to which a phase tracking reference signal (PTRS) is assigned in a wireless communication system according to various embodiments of the present disclosure.

Referring to Figure 1, the horizontal axis represents the time domain and the vertical axis represents the frequency domain. The minimum unit in the time domain is an OFDM symbol, and the minimum unit in the frequency domain is a subcarrier. The basic unit of resources in the time-frequency domain is a resource element (RE), which can be expressed as an OFDM symbol index and a subcarrier index. 14 OFDM symbols can make up 1 slot, and 12 subcarriers can make up 1 RB (resource block).

Figure 1 shows radio resources to which a plurality of different types of signals are allocated. Referring to FIG. 1, assuming there is 1 slot consisting of 14 OFDM symbols, OFDM symbol index 0 (or OFDM symbol index 0, 1) may be allocated for CORESET (control resource set). A physical downlink control channel (PDCCH) transmitted on CORESET may include downlink control information (DCI) for scheduling a physical downlink shared channel (PDSCH).

In Figure 1, it is assumed that DMRS ports 0/1/2/3 all form the same DMRS port group. P0 DMRS and P1 DMRS having different OCC (orthogonal cover codes) may overlap in the frequency domain at the location of P0/P1 DMRS. Additionally, at the location of the P2/P3 DMRS, the P2 DMRS and DMRS having different OCCs may overlap in the frequency domain. For channel estimation in radio resources where DMRS does not exist in FR2, where phase noise is large, PTRS can be transmitted on a subcarrier corresponding to a specific DMRS antenna port within a resource block (RB). For example in FIG. 1, PTRS may be placed in a resource element (RE) where CORESET and DMRS do not exist on a subcarrier with an index of 0.

PTRSs are placed at a location (i.e., subcarrier) on the frequency axis of the RE where the DMRS exists. PTRSs may not be placed in every OFDM symbol, but may be placed at predetermined intervals on the time axis. Figure 1 illustrates an embodiment in which PTRSs are arranged at intervals of two OFDM symbols (i.e., an embodiment in which PTRSs are arranged at intervals of three OFDM symbols), but is not limited thereto, and PTRSs arranged on one subcarrier are divided into integers. It can be arranged at intervals of OFDM symbols.

2 illustrates common phase error (CPE) according to various embodiments of the present disclosure.

Phase noise (PN) generated in the time-domain during the signal transmission and reception process gives the same gain to the received signal of any RE within the OFDM symbol in the frequency domain and maintains the same phase. Rotation can cause inter-carrier interference (ICI). At this time, the variable consisting of the same gain and the same phase can be called CPE (common phase error).

Referring to FIG. 2, the horizontal axis of the graph shows the real index of the CPE, and the vertical axis shows the imaginary index of the CPE. In the graph, points with a CPE gain of 0.991 are shown at 1° intervals between phase -8° and 8°. Additionally, the graph shows the constellations of 14 CPEs corresponding to 14 OFDM symbols.

The points indicating 14 CPEs corresponding to 14 OFDM symbols have phase values irregularly distributed between -8° and 8°, and the CPE gain may be approximately 1. Since the 14 CPE values corresponding to 14 OFDM symbols are irregularly distributed, it is necessary to estimate the difference in CPE angle and apply the estimated value of the CPE angle difference to estimate the channel.

Below, contents related to the contents described above are defined as mathematical equations and parameters. OFDM symbol and sample signal received from Can be expressed as <Equation 1> below.

In equation 1 Silver OFDM symbol and sample PN in is a set of delays when CIR (channel impulse response) has nonzero power at a specific delay, Silver OFDM symbol delay This is the CIR corresponding to, Silver OFDM symbol and sample It is a transmitted signal from is modulo operator, Silver OFDM symbol and sample It means noise in .

Received signal in time domain a frequency domain signal By converting to , the following <Equation 2> can be derived.

In equation 2 is CPE, Silver OFDM symbol and frequency is the CFR in Silver OFDM symbol and frequency It is a frequency domain transmission signal in Silver OFDM symbol and frequency refers to noise and interference signals in

CPE in <Equation 2> can be expressed as an approximation as shown in <Equation 3>.

In <Equation 3> is the OFDM symbol Defined as CPE angle. Therefore, in equation 2 Silver OFDM symbol frequency at It can be interpreted as a rotated CFR.

As shown in FIG. 3, when estimating the rotated CFR in an OFDM symbol in which a DMRS does not exist and a PTRS exists, the pre-estimated rotated CFR is copied from nearby OFDM symbols with a DMRS, and CPE is performed using PTRS. After estimating the angle difference, the CFR can be estimated by rotating the copied rotated CFR above by the CPE angle difference.

Meanwhile, the channel estimation process for the existing PTRS RE can be explained as follows. Transmit port 0, receive antenna , OFDM symbol where DMRS exists and frequency The rotated CFR estimate at Let's say RE with PTRS present Since DMRS does not exist in , the receiving end cannot immediately obtain the rotated CFR estimate for PTRS RE. Accordingly, the receiving end is connected to the RE where PTRS exists (PTRS RE). And the frequency at which PTRS RE exists PTRS RE to obtain rotated CFR estimates in DMRS RE close to First obtain the rotated CFR estimate of . receiving antenna , OFDM symbol where PTRS exists And the frequency at which PTRS RE exists The received signal from Let's say Then, the OFDM symbol and OFDM symbols Estimate of the CPE angle difference at can be obtained as in <Equation 4> below.

In <Equation 4>, it is assumed that the transmitting end and the receiving end promise each other that PTRS will be transmitted from port 0 of the transmitting end, is the angle operator, is the conjugate operator. Then, the OFDM symbol where DMRS does not exist and PTRS exists The rotated CFR estimate can be obtained as shown in Equation 5 below.

In <Equation 5> Silver OFDM symbol OFDM symbol with DMRS close to , frequency , sending port , and receiving antenna It means the rotated CFR estimate at .

3 illustrates channel frequency response (CFR) according to various embodiments of the present disclosure. Figure 3 shows the frequency index 0 of 14 OFDM symbols (e.g., RE with subcarrier index 0 in Figure 1) when the carrier frequency is 28GHz, SCS (subcarrier spacing) is 60Khz, and the receiver speed is 50km/h. It shows the change in CFR, and shows a graph of the change in the real part of the CFR and a graph of the change in the imaginary part of the CFR.

Referring to FIG. 3, CFR may take the form of a second-order parabolic function throughout 14 OFDM symbol sections, but within 2 to 3 OFDM symbol sections, CFR may approximately take the form of a first-order linear function.

In a wireless channel environment that changes with time, when estimating the channel from an RE to which a Phase Tracking Reference Signal (PTRS) is assigned (i.e., an RE to which no DMRS is assigned), 1 to which the closest DMRS is assigned according to the conventional method If only the CFR estimates of the symbols are used, errors in channel estimation may be large.

According to various embodiments of the present disclosure, in order to reduce the above-described error in channel estimation, two symbols to which a DMRS is assigned close to a RE to which a PTRS is assigned are linearly interpolated or extrapolated to obtain a RE to which a PTRS is assigned. An estimate of the rotated CFR can be obtained. For example, in FIG. 3, there are CFR values for the case where the index of the OFDM symbol is 2 (310) and 4 (330), and the CFR value for the case where the index of the symbol is 3 (320) and the index of the symbol is 6. If the CFR value of case 340 is not known, linear interpolation is performed on the CFR values of case 310 where the index of the symbol is 2 and case 330 of case 4 to obtain the CFR value of case 320 where the index of the symbol is 3. It can be estimated, and the CFR value when the symbol index is 6 (340) can be estimated by performing linear extrapolation on the CFR values when the symbol index is 2 (310) and when the symbol index is 4 (330).

FIG. 4 illustrates OPDM symbols on a specific subcarrier according to various embodiments of the present disclosure on the time axis.

Referring to Figure 4, the horizontal axis represents the time domain and the vertical axis represents the frequency domain. In the time-frequency domain, the basic unit of resources is RE (resource element), which can be represented by an OFDM symbol index on the horizontal axis and a subcarrier index on the vertical axis. Figure 4 shows 14 OFDM symbols, or 14 REs, for a specific subcarrier.

PTRSs are placed at a location (i.e., subcarrier) on the frequency axis of the RE where the DMRS exists. PTRSs may not be placed in every OFDM symbol, but may be placed at predetermined intervals on the time axis. For example, in FIG. 4, an embodiment is shown in which the PTRS is placed at RE 3, RE 6, RE 9, and 12 with an interval of two OFDM symbols, but the present invention is not limited to this, and the PTRS is placed on one subcarrier. They may be arranged at intervals of an integer number of OFDM symbols.

According to an embodiment according to the present disclosure, the UE may perform 1-dimensional rotated CFR estimation for each RE where a DMRS exists. Subsequently, the UE can select two CFR estimates: REs in which a DMRS exists (hereinafter referred to as DMRS REs) close to an RE in which a PTRS exists (hereinafter referred to as PTRS RE). The UE may obtain a first CFR estimate, which is a temporary CFR estimate of the PTRS RE, by performing linear interpolation on the CFR estimates of the two selected DMRS REs. According to various embodiments according to the present disclosure, the first CFR estimate may be obtained by performing not only linear interpolation but also linear extrapolation on the two selected CFR estimates.

According to various embodiments of the present disclosure, the first CFR estimate may be obtained based on DMRS REs adjacent to the PTRS RE in the time domain. The DMRS REs may be the two closest REs in the time domain from the PTRS RE. For example, the first CFR estimate of PTRS RE 3 may be obtained based on RE 2 and RE 4, which are the DMRS REs closest to RE 3 in the time domain. At this time, DMRS REs close to a PTRS RE may mean the two REs closest to the PTRS RE in the time domain, but are not limited to this embodiment. The DMRS REs closest to a PTRS RE may be defined to include one RE closest in the forward direction and one RE closest in the reverse direction in the time domain, and one RE closest to the forward (or reverse) direction in the time domain. Next, it may be defined to include one adjacent RE.

According to various embodiments of the present disclosure, the terminal may calculate an estimate of the common phase error (CPE) angle difference for the PTRS RE. The terminal may obtain a second CFR estimate by applying the estimate of the CPE angle difference to the first CFR estimate obtained according to the process described above. The UE may perform phase tracking of the RE to which the PTRS is assigned based on the obtained second CFR estimate. In the example of FIG. 4, the terminal may calculate an estimate of the CPE angle difference for RE 3 to which RTRS is assigned, and apply the estimate of the CPE angle difference to the first CFR estimate obtained based on RE 2 and RE 4 to obtain RE A second CFR estimate for 3 can be obtained.

Figure 5 illustrates a channel estimation operation of a terminal according to various embodiments of the present disclosure.

The channel estimation operation of the terminal shown in FIG. 5 may be performed based on DMRS and PTRS, that is, downlink signals, received by the terminal from the base station.

Referring to FIG. 5, in step 510, the UE may perform linear interpolation based on the two REs to which the DMRS is assigned to obtain the first CFR estimate in the RE to which the PTRS is assigned.

After performing 1-dimensional rotated CFR estimation in the RE in which a DMRS exists, the UE can select the CFR estimates of two REs in which a DMRS exists that are close to the RE in which a PTRS exists. Linear interpolation can be performed on the two selected CFR estimates to obtain a first CFR estimate (or first CFR estimate), which is a temporary CFR estimate of the RE where the PTRS exists. According to various embodiments according to the present disclosure, the first CFR estimate may be obtained by performing not only linear interpolation but also linear extrapolation on the two selected CFR estimates.

According to various embodiments of the present disclosure, the first CFR estimate may be obtained based on REs assigned a DMRS adjacent to the RE assigned a PTRS in the time domain. The REs to which the DMRS is assigned may be the two REs closest to the RE to which the PTRS is assigned in the time domain. For example, in Figure 4, the first CFR estimate of RE 3, a RE to which a PTR is assigned, is the closest to RE 3 among REs to which adjacent DMRs are assigned (RE 1, RE 2, RE 4, and RE 5) in the time domain. It can be obtained based on the two adjacent REs, RE 2 and RE 4.

In step 520, the UE may calculate an estimate of the common phase error (CPE) angle difference for the RE to which the PTRS is assigned. The UE can filter received signals at frequencies where REs where PTRSs exist using a whitened matched filter in the spatial domain. The CPE angle difference can be estimated by accumulating the filtered result values in the white matched filter.

According to various embodiments according to the present disclosure, transmission port 0, reception antenna , OFDM symbol where DMRS exists and frequency The rotated CFR estimate at Let's say, OFDM symbol where PTRS exists at and The first CFR estimate performed by linear interpolation or linear extrapolation with When this is said, the first CFR estimate is The vector collected across the two receiving antennas is as shown in Equation 6 below.

Frequency where REs with PTRS assigned exist Received signal from second The vector collected across the two receiving antennas is as shown in Equation 7 below.

remind and An estimate of the CPE angle difference can be obtained using , and the estimate of the CPE angle difference is as shown in Equation 8 below.

remind Silver OFDM symbol and frequency receiving antenna from It refers to the inverse matrix of the estimated value of the covariance matrix that shows the correlation of the noises in the reception antenna.

In step 530, the terminal may obtain a second CFR estimate by applying the estimate of the CPE angle difference to the first CFR estimate.

According to various embodiments according to the present disclosure, the second CFR estimate, which is the rotated CFR estimate in the RE where PTRS exists, is expressed as Equation 9 below.

remind is the sending port, is the receiving antenna, means a RE where PTRS exists.

The UE may perform phase tracking of the RE to which the PTRS is assigned based on the obtained second CFR estimate. PTRS can not only be used to remove phase noise through CPE estimation, but can also be used for channel estimation in the frequency domain by performing phase tracking. Due to this channel estimation, the channel estimation result can be efficiently compensated when the channel changes rapidly on the time axis, and channel degradation that may occur in the high frequency band can be minimized.

In the above, the embodiment has been described based on the downlink case in which the terminal receives DMRS and PTRS from the base station, but the same process can also be applied to the uplink case. That is, of course, the above-described operations can be applied in the same or similar manner to the uplink case in which the base station receives DMRS and PTRS from the terminal.

Figure 6 illustrates a channel estimation operation of a terminal according to various embodiments of the present disclosure. FIG. 6 shows the channel estimation operation of the terminal in FIG. 5 in detail, and content that overlaps with the content described in FIG. 5 is omitted in FIG. 6.

Referring to FIG. 6, in step 610, the UE can obtain a CFR estimate of the RE where the DMRS exists by performing 1-dimensional rotated CFR estimation on the RE where the DMRS exists.

In step 620, the UE selects CFR estimates from two REs with a DMRS that are close to the RE with a PTRS, and performs linear interpolation or linear extrapolation on the two selected CFR estimates to obtain a PTRS. A first CFR estimate, which is a provisional CFR estimate of an existing RE, can be obtained. According to various embodiments according to the present disclosure, the first CFR estimate may be obtained by performing not only linear interpolation but also linear extrapolation on the two selected CFR estimates.

In step 630, the UE may filter received signals at a frequency where an RE where a PTRS exists using a whitened matched filter in the spatial domain.

In step 640, the terminal can estimate the CPE angle difference by accumulating the result of filtering in the white matched filter.

In step 650, the UE may obtain a second CFR estimate by rotating the CPE angle difference estimate to the first CFR estimate for the RE where PTRS exists. Afterwards, the UE may perform phase tracking of the RE to which the PTRS is assigned based on the obtained second CFR estimate.

Figure 7 illustrates a channel estimation operation of a terminal according to various embodiments of the present disclosure.

Referring to FIG. 7, in step 710, the UE can obtain the first CFR estimate of the RE where the DMRS exists by performing 1-dimensional rotated CFR estimation on the RE where the DMRS exists.

In step 720, the terminal can define a cost function that uses the difference between the two CPE angles as a variable. The CPE angle difference, which is a variable in the cost function, may mean the difference between the CPE angle of the RE where PTRS exists and the CPE angle of one of the two REs where DMRS exists.

In step 730, the terminal can set the initial value of the CPE angle difference, which is two variables of the cost function. The initial value of the CPE angle difference can be set according to preset conditions.

In step 740, the UE can estimate the difference between the two CPE angles based on the RE in which the PTRS exists. The CPE angle difference can be estimated using an iterative algorithm on the initial values of the two variables of the set cost function. The iterative algorithm may include, for example, the Levenberg-Marquardt (LM) algorithm.

In step 750, the UE rotates the CFR estimates of two OFDM symbols in which PTRS and DMRS close to the time axis exist based on the estimates of the two estimated CPE angle differences, respectively, with the corresponding CPE angle difference estimates (two first CFR estimate), and the second estimate can be obtained through linear interpolation or linear extrapolation of the two first CFR estimates. Afterwards, the UE may perform phase tracking of the RE to which the PTRS is assigned based on the obtained second CFR estimate.

Figure 8 illustrates a channel estimation operation of a terminal according to various embodiments of the present disclosure. FIG. 8 shows an operation in which the terminal estimates the difference in CPE angles, which are two variables of the cost function, using an iterative algorithm in steps 730 to 740 of FIG. 7 .

In step 810, the terminal can set the initial value of the CPE angle difference, which is two variables of the cost function. The initial value of the CPE angle difference can be set according to preset conditions.

In step 820, the terminal determines whether the stopping condition for executing the iterative algorithm used to obtain an estimate of the CPE angle difference is met. If the conditions for stopping the iterative algorithm execution are met, the terminal can stop repeated execution of the iterative algorithm and end the operation. If the stop condition for executing the iterative algorithm is not met, the terminal may perform the operation of step 830.

In step 830, the terminal may calculate a gradient from an estimate of the difference between two potential CPE angles and a cost function.

In step 840, the terminal can obtain a new estimate of the CPE angle difference by performing the Levenberg-Marquardt (LM) algorithm included in the iterative algorithm. The terminal can update the estimate of the difference between the two new CPE angles, which are variables of the cost function.

Below, the process of obtaining the CPE angle difference based on the cost function according to the embodiment described in FIGS. 7 and 8 will be described in detail. Below, an embodiment will be described based on the downlink case in which the terminal receives DMRS and PTRS, but the same process can also be applied to the uplink case. That is, of course, the following operations can be applied in the same or similar manner to the uplink case where the base station receives DMRS and PTRS from the terminal.

The UE performs 1-dimensional rotated CFR estimation in the DMRS RE, and the UE obtains a rotated CFR estimate for each of the two DMRS REs close to the PTRS RE. Next, in order to calculate the CPE angle difference of the PTRS RE, the terminal defines a cost function with the two CPE angle differences as variables and obtains the two CPE angle difference values that minimize the cost function. In order to obtain the two parameters that minimize the cost function, an iterative algorithm-based method can be used instead of the close form-based method, and the terminal must set an initial value to perform this iterative algorithm method.

The UE obtains two whitened matched filter outputs in the space domain for two CFR estimates for two DMRS REs received on a subcarrier where a PTRS RE exists. The terminal multiplies the outputs of the two whitened matched filters by a predetermined weight and obtains, for each, two metrics accumulated over the frequency at which the PTRS RE exists. Additionally, the UE obtains one metric that obtains the correlation of the rotated CFR estimate vectors of the two previously acquired DMRS REs. The terminal can determine the initial values of the two variables of the previously defined cost function by comparing the sizes of these three metrics.

To describe the embodiment described in FIG. 8 in more detail, the UE can estimate CPE angle difference values for two DMRS REs through an iterative task based on the LM algorithm. In this process, the terminal can repeatedly perform the process of updating two variables based on a matrix obtained by partial differentiation of the cost function, and through this repetition, CPE angle difference values for the two DMRS REs can be obtained. You can. In addition, the terminal reflects the CPE angle difference values in the rotated CFR estimates for each of the two DMRS REs and then estimates the rotated CFR of the PTRS RE through a linear weighted sum.

What is explained in FIGS. 7 and 8 will be explained in more detail through the equation below. The cost function can be expressed as <Equation 10> below.

In Equation 10, the vector Is and Silver OFDM symbol and OFDM symbols It is the CPE angle difference between Silver OFDM symbol and OFDM symbols It means the difference in CPE angle between second Vector collected across two receiving antennas Define. second Vector collected across two receiving antennas Define.

Meanwhile, , , Can be defined as <Equation 11> to <Equation 16> below, respectively.

Meanwhile, vector initial value of The process of finding can be accomplished through observation of the cost function in Equation 10. On the other hand, if there is no separate standard in the process of obtaining the initial value of the cost function, there may be cases where the obtained predetermined value is the local minimum rather than the global minimum, so a predetermined standard is needed to efficiently obtain the initial value. do. <Equation 17> below can be applied to this initial value determination process.

Initial value of the cost function according to <Equation 10> and <Equation 17> Once this is determined, the terminal creates a vector through repeated performance such as the LM algorithm. An estimate can be obtained.

First, the terminal uses a rotated CFR vector Calculate the whitened version as shown in <Equation 18> below.

Subsequently, the terminal rotates the CFR vector The whitened version of is calculated as in <Equation 19>.

Subsequently, the terminal receives the vector from PTRS RE The whitened version of is calculated as <Equation 20>.

The terminal is a function is defined as <Equation 21>,

function in the second iteration gradient Can be expressed according to <Equation 22> and <Equation 23> below.

Parameters appearing in <Equation 22> and <Equation 23> can be defined according to <Equation 24> to <Equation 26> below.

Additionally, in <Equation 26> silver vector of This is the second entry, silver vector of It is the th entry, and the relationship of <Equation 27> below can be defined in relation to Equation 23.

Parameters related to <Equation 27> may be defined as <Equation 28> to <Equation 30> below.

Meanwhile, according to the above-described repetitive process, th iteration ( ) in vector Can be expressed as <Equation 31> and <Equation 32> below.

Vector at the end of the iteration second Let's say Then, sending port , receiving antenna , OFDM symbol where DMRS does not exist and PTRS exists and frequency The CFR estimate rotated in can be calculated as <Equation 33>.

In <Equation 33> is the sending port , receiving antenna , OFDM symbol (or RE) where DMRS exists and frequency is the CFR estimate vector rotated from , is the sending port , receiving antenna , OFDM symbol (or RE) where DMRS exists and frequency is the CFR estimate vector rotated from .

When CFR estimate vectors (or CFR estimate values) for two DMRS REs are respectively obtained through the above-described process, the terminal calculates the rotated CFR for the two DMRS REs by applying the CPE angle difference to each of the two CFR estimate vectors. values can be obtained. Subsequently, the UE can obtain the CFR value for the PTRS RE through a procedure of linearly interpolating or extrapolating the rotated CFR values obtained for the two DMRS REs.

Figure 9 shows a BLER versus SNR graph according to various embodiments of the present disclosure.

The graph in Figure 9 shows the number of REs with a carrier frequency of 28 GHz, 4x2 TDLA-30 channel, SCS = 60kHz, modulation and coding (MCS) = 9, MCS table = 2, 16 quadrature amplitude modulation (QAM), and DMRS. This shows the BLER performance obtained through a 1200 slot Monte Carlo experiment when there are 4, 1 RE for CORESET, 2 layers of PDSCH, and 50 km/h speed. The horizontal axis of the graph represents Signal Noise Ratio (SNR), and the vertical axis represents BLER (Block Error Rate).

In Figure 9, the SNR-BLER graph shows a case where the CFR estimate in the RE to which PTRS is assigned is obtained using one RE to which DMRS is assigned (Baseline), and linear interpolation or extrapolation is performed using two REs to which DMRS is assigned. When the CFR estimate in the RE to which the PTRS is assigned is obtained by performing (Alt 1) (e.g., the operation of the UE in FIG. 5), the BLER relative to each SNR is indicated.

Referring to FIG. 9, in the case where a CFR estimate in a RE to which a PTRS is assigned is obtained by performing linear interpolation or extrapolation using two REs to which a DMRS is assigned, the PTRS is assigned using one RE to which an MRS is assigned. It can be seen that the reduction rate of BLER is greater as SNR increases compared to the case where CFR estimates were obtained from RE. This shows that the wireless channel environment changes over time, and the technology for obtaining a CFR estimate using two REs assigned to DMRS in a high-frequency environment where phase noise exists can have very excellent reception performance. there is.

Figure 10 shows a BLER (Block Error Rate) versus SNR graph according to various embodiments of the present disclosure.

Referring to FIG. 10, the graph 1000 shows a carrier frequency of 28 GHz, 4x2 TDLA-30 channel, SCS = 60kHz, modulation and coding (MCS) = 9, MCS table = 2, 16 quadrature amplitude modulation (QAM), and DMRS. The BLER performance obtained through a 1200 slot Monte Carlo experiment is shown when the number of existing REs is 4, the RE for CORESET is 1, the number of PDSCH layers is 2, and the speed is 50 km/h. The horizontal axis of the graph represents the Signal Noise Ratio (SNR), and the vertical axis represents the Block Error Rate (BLER). The SNR-BLER graph in FIG. 10 includes the graph shown in FIG. 9.

In Figure 10, the SNR-BLER graph shows that when the CFR estimate in the RE to which PTRS is assigned is obtained using one RE to which DMRS is assigned (Baseline), linear interpolation or extrapolation is performed using two REs to which DMRS is assigned. When a CFR estimate is obtained in a RE to which a PTRS is assigned (Alt 1) (e.g., the operation of the UE in FIG. 5), the difference between the two CPE angles is used as a variable using the two REs to which a DMRS is assigned. When the CFR estimate is obtained by performing an iterative algorithm on the cost function (Alt 2) (for example, the operation of the terminal in FIG. 7), the BLER relative to each SNR is shown.

Referring to FIG. 10, in the case where a CFR estimate is obtained by performing an iterative algorithm using two REs to which DMRS is assigned and a cost function with the difference in two CPE angles as a variable, the CFR estimate is obtained using one RE to which MRS is assigned. It can be seen that the reduction rate of BLER is greater as SNR increases compared to the case where the CFR estimate is obtained from the RE where PTRS is assigned. This shows that the wireless channel environment changes over time, and the technology for obtaining a CFR estimate using two REs assigned to DMRS in a high-frequency environment where phase noise exists can have very excellent reception performance. there is.

Figure 11 shows the structure of a terminal 1100 according to various embodiments of the present disclosure.

The configuration illustrated in FIG. 11 can be understood as the configuration of the terminal 1100. Terms such as '... unit' and '... unit' used hereinafter refer to a unit that processes at least one function or operation, and may be implemented as hardware, software, or a combination of hardware and software. .

Referring to FIG. 11, the terminal 1100 includes a communication unit 1110, a storage unit 1120, and a control unit 1130.

The communication unit 1110 performs functions for transmitting and receiving signals through a wireless channel. For example, the communication unit 1110 performs a conversion function between baseband signals and bit strings according to the physical layer specifications of the system. For example, when transmitting data, the communication unit 1110 generates complex symbols by encoding and modulating the transmission bit string. Additionally, when receiving data, the communication unit 1110 restores the received bit stream by demodulating and decoding the baseband signal. Additionally, the communication unit 1110 upconverts the baseband signal into an RF band signal and transmits it through an antenna, and downconverts the RF band signal received through the antenna into a baseband signal. For example, the communication unit 1110 may include a transmission filter, a reception filter, an amplifier, a mixer, an oscillator, a DAC, an ADC, etc.

Additionally, the communication unit 1110 may include multiple transmission and reception paths. Furthermore, the communication unit 1110 may include an antenna unit. The communication unit 1110 may include at least one antenna array composed of multiple antenna elements. In terms of hardware, the communication unit 1110 may be composed of digital circuits and analog circuits (eg, radio frequency integrated circuit (RFIC)). Here, the digital circuit and analog circuit can be implemented in one package. Additionally, the communication unit 1110 may include multiple RF chains. The communication unit 1110 may perform beamforming. The communication unit 1110 may apply a beamforming weight to the signal to be transmitted and received in order to give directionality according to the settings of the control unit 1130. According to one embodiment, the communication unit 1110 may include a radio frequency (RF) block (or RF unit). The RF block may include a first RF circuitry related to an antenna and a second RF circuitry related to baseband processing. The first RF circuit may be referred to as RF-A (antenna). The second RF circuit may be referred to as RF-B (baseband).

Additionally, the communication unit 1110 can transmit and receive signals. For this purpose, the communication unit 1110 may include at least one transceiver. The communication unit 1110 can receive a downlink signal. Downlink signals include synchronization signal (SS), reference signal (RS) (e.g., demodulation (DM)-RS, phase tracking reference signal (PTRS)), and system information (e.g., MIB, SIB, RMSI (e.g., It may include remaining system information (OSI), other system information (OSI), configuration message, control information, or downlink data, etc. In addition, the communication unit 1110 can transmit an uplink signal. Uplink signals include random access-related signals (e.g., random access preamble (RAP) (or Msg1 (message 1)), Msg3 (message 3)), and reference signals (e.g., sounding reference signal (SRS)). , DMRS, PTRS), or power headroom report (PHR), etc.

Additionally, the communication unit 1110 may include different communication modules to process signals in different frequency bands. Furthermore, the communication unit 1110 may include multiple communication modules to support multiple different wireless access technologies. For example, different wireless access technologies include Bluetooth low energy (BLE), Wireless Fidelity (Wi-Fi), WiFi Gigabyte (WiGig), and cellular networks (e.g., Long Term Evolution (LTE), new wireless network (NR)). radio), etc. In addition, different frequency bands include super high frequency (SHF) (e.g., 2.5GHz, 5Ghz) bands, millimeter wave (e.g., 38GHz, 60GHz, etc.) bands. In addition, the communication unit 1110 may provide the same wireless access method on different frequency bands (e.g., unlicensed band for licensed assisted access (LAA), citizens broadband radio service (CBRS) (e.g., 3.5 GHz)). You can also use technology.

The communication unit 1110 transmits and receives signals as described above. Accordingly, all or part of the communication unit 1110 may be referred to as a ‘transmitting unit’, a ‘receiving unit’, or a ‘transmitting/receiving unit’. Additionally, in the following description, transmission and reception performed through a wireless channel are used to mean that the processing as described above is performed by the communication unit 1110.

The storage unit 1120 stores data such as basic programs, application programs, and setting information for the operation of the terminal 1100. The storage unit 1120 may be comprised of volatile memory, non-volatile memory, or a combination of volatile memory and non-volatile memory. And, the storage unit 1120 provides stored data according to the request of the control unit 1130.

The control unit 1130 controls the overall operations of the terminal 1100. For example, the control unit 1130 transmits and receives signals through the communication unit 1110. Additionally, the control unit 1130 records and reads data from the storage unit 1120. Additionally, the control unit 1130 can perform protocol stack functions required by communication standards. For this purpose, the control unit 1130 may include at least one processor. The control unit 1130 may include at least one processor or microprocessor, or may be part of a processor. Additionally, a portion of the communication unit 1110 and the control unit 1130 may be referred to as CP. The control unit 1130 may include various modules for performing communication. According to various embodiments, the control unit 1130 may control the terminal to perform operations according to various embodiments.

FIG. 12 illustrates the structure of a base station 1200 in a wireless communication system according to various embodiments of the present disclosure.

Referring to FIG. 12, the base station 1200 includes a communication unit 1210, a storage unit 1220, and a control unit 1230.

The communication unit 1210 performs functions for transmitting and receiving signals through a wireless channel. For example, the communication unit 1210 performs a conversion function between baseband signals and bit strings according to the physical layer specifications of the system. For example, when transmitting data, the communication unit 1210 generates complex symbols by encoding and modulating the transmission bit string. Additionally, when receiving data, the communication unit 1210 restores the received bit stream by demodulating and decoding the baseband signal. Additionally, the communication unit 1210 upconverts the baseband signal into a radio frequency (RF) band signal and transmits it through an antenna, and downconverts the RF band signal received through the antenna into a baseband signal.

To this end, the communication unit 1210 may include a transmission filter, a reception filter, an amplifier, a mixer, an oscillator, a digital to analog convertor (DAC), an analog to digital convertor (ADC), etc. Additionally, the communication unit 1210 may include multiple transmission and reception paths. Furthermore, the communication unit 1210 may include at least one antenna array composed of a plurality of antenna elements. In terms of hardware, the communication unit 1210 may be composed of a digital unit and an analog unit, and the analog unit is divided into a number of sub-units according to operating power, operating frequency, etc. It can be configured.

The communication unit 1210 can transmit and receive signals. For this purpose, the communication unit 1210 may include at least one transceiver. For example, the communication unit 1210 may transmit a synchronization signal, reference signal, system information, message, control information, or data. Additionally, the communication unit 1210 can perform beamforming.

The communication unit 1210 transmits and receives signals as described above. Accordingly, all or part of the communication unit 1210 may be referred to as a ‘transmitting unit’, a ‘receiving unit’, or a ‘transmitting/receiving unit’. Additionally, in the following description, transmission and reception performed through a wireless channel are used to mean that the processing as described above is performed by the communication unit 1210.

The storage unit 1220 stores data such as basic programs, application programs, and setting information for operation of the base station. The storage unit 1220 may include memory. The storage unit 1220 may be comprised of volatile memory, non-volatile memory, or a combination of volatile memory and non-volatile memory. And, the storage unit 1220 provides stored data according to the request of the control unit 1230.

The control unit 1230 controls the overall operations of the base station 1200. For example, the control unit 1230 transmits and receives signals through the communication unit 1210. Additionally, the control unit 1230 records and reads data from the storage unit 1220. Additionally, the control unit 1230 can perform protocol stack functions required by communication standards. For this purpose, the control unit 1230 may include at least one processor.

The configuration of the base station 1200 shown in FIG. 12 is only an example of a base station, and examples of base stations that perform various embodiments of the present disclosure are not limited to the configuration shown in FIG. 12. That is, according to various embodiments, some configurations may be added, deleted, or changed.

In FIG. 12, the base station 1200 is described as one entity, but the present disclosure is not limited thereto. The base station 1200 according to various embodiments of the present disclosure may be implemented to form an access network having an integrated deployment as well as a distributed deployment. According to one embodiment, the base station is divided into a central unit (CU) and a digital unit (DU), with the CU performing upper layer functions (e.g., packet data convergence protocol (PDCP, RRC)) and the DU performing lower layer functions. It can be implemented to perform (lower layers) (e.g. MAC (medium access control), PHY (physical)). The base station's DU can form beam coverage on the wireless channel.

Meanwhile, the embodiments of the present invention disclosed in the specification and drawings are merely provided as specific examples to easily explain the technical content of the present invention and to facilitate understanding of the present invention, and are not intended to limit the scope of the present invention. In other words, it is obvious to those skilled in the art that other modifications based on the technical idea of the present invention can be implemented. Additionally, each of the above embodiments can be operated in combination with each other as needed.

As described above, a method for a terminal (e.g., 1100 in FIG. 11) to receive a phase tracking reference signal (PTRS) in a wireless communication system according to various embodiments disclosed in this document uses a demodulation reference signal (DMRS). Obtaining a first CFR estimate in the RE to which the PTRS is assigned by performing linear interpolation based on two resource elements (REs) to which the PTRS is assigned, a CPE angle for the RE to which the PTRS is assigned. Calculating an estimate of the difference, performing phase tracking of the RE to which the PTRS is assigned based on a second CFR estimate obtained by applying the estimate of the CPE angle difference to the first CFR estimate. may include.

According to various embodiments disclosed in this document, the estimated value of the CPE angle difference is obtained by filtering the received signal at the frequency where the RE to which the PTRS is assigned is present through a whitened matched filter in the spatial domain. It can be obtained by performing a filtering step and a step of accumulating the filtered result value in the white matched filter.

According to various embodiments disclosed in this document, obtaining the first CFR estimate includes obtaining based on REs to which the DMRS is assigned that are adjacent in the time domain to the RE to which the PTRS is assigned, The REs to which the DMRS is assigned may be the two closest REs in the time domain from the RE to which the PTRS is assigned.

According to various embodiments disclosed in this document, the two REs to which the DMRS is assigned and the RE to which the PTRS is assigned may be located within a physical downlink shared channel (PDSCH) resource. According to various embodiments disclosed in this document, the two REs to which the DMRS is assigned and the RE to which the PTRS is assigned may be located on the same subcarrier.

As described above, in a wireless communication system according to various embodiments disclosed in this document, a terminal receiving a phase tracking reference signal (PTRS) includes a transceiver and at least one processor, and the at least one processor includes a DMRS By performing linear interpolation based on two REs (resource elements) to which a (demodulation reference signal) is assigned, a first CFR estimate is obtained in the RE to which the PTRS is assigned, and the RE to which the PTRS is assigned is obtained. Calculate an estimate of the CPE angle difference, and perform phase tracking of the RE to which the PTRS is assigned based on a second CFR estimate obtained by applying the estimate of the CPE angle difference to the first CFR estimate. It can be set to perform.

According to various embodiments disclosed in this document, the at least one processor determines the estimated value of the CPE angle difference by white matching the received signal at the frequency where the RE to which the PTRS is assigned is present in the spatial domain. It can be set to be obtained by performing filtering on a whitened matched filter and accumulating the result of filtering on the white matched filter.

According to various embodiments disclosed in this document, the at least one processor sets the first CFR estimate to be obtained based on REs to which the DMRS is assigned that are adjacent in the time domain to the RE to which the PTRS is assigned; , the REs to which the DMRS is assigned may be the two closest REs in the time domain from the RE to which the PTRS is assigned.

According to various embodiments disclosed in this document, the two REs to which the DMRS is assigned and the RE to which the PTRS is assigned may be located within a physical downlink shared channel (PDSCH) resource.

According to various embodiments disclosed in this document, the two REs to which the DMRS is assigned and the RE to which the PTRS is assigned may be located on the same subcarrier.

As described above, a method for a base station (e.g., 1200 in FIG. 12) to receive a phase tracking reference signal (PTRS) in a wireless communication system according to various embodiments disclosed in this document uses a demodulation reference signal (DMRS). Obtaining a first CFR estimate in the RE to which the PTRS is assigned by performing linear interpolation based on two resource elements (REs) to which the PTRS is assigned, a CPE angle for the RE to which the PTRS is assigned. Calculating an estimate of the difference, performing phase tracking of the RE to which the PTRS is assigned based on a second CFR estimate obtained by applying the estimate of the CPE angle difference to the first CFR estimate. may include.

According to various embodiments disclosed in this document, the estimated value of the CPE angle difference is obtained by filtering the received signal at the frequency where the RE to which the PTRS is assigned is present through a whitened matched filter in the spatial domain. It can be obtained by performing a filtering step and a step of accumulating the filtered result value in the white matched filter.

According to various embodiments disclosed in this document, obtaining the first CFR estimate includes obtaining based on REs to which the DMRS is assigned that are adjacent in the time domain to the RE to which the PTRS is assigned, The REs to which the DMRS is assigned may be the two closest REs in the time domain from the RE to which the PTRS is assigned.

According to various embodiments disclosed in this document, the two REs to which the DMRS is allocated and the RE to which the PTRS is allocated may be located within a physical uplink shared channel (PUSCH) resource.

According to various embodiments disclosed in this document, the two REs to which the DMRS is assigned and the RE to which the PTRS is assigned may be located on the same subcarrier.

As described above, in a wireless communication system according to various embodiments disclosed in this document, a base station for receiving a phase tracking reference signal (PTRS) includes a transceiver and at least one processor, and the at least one processor includes a DMRS By performing linear interpolation based on two REs (resource elements) to which a (demodulation reference signal) is assigned, a first CFR estimate is obtained in the RE to which the PTRS is assigned, and the RE to which the PTRS is assigned is obtained. Calculate an estimate of the CPE angle difference, and perform phase tracking of the RE to which the PTRS is assigned based on a second CFR estimate obtained by applying the estimate of the CPE angle difference to the first CFR estimate. It can be set to perform.

According to various embodiments disclosed in this document, the at least one processor determines the estimated value of the CPE angle difference by white matching the received signal at the frequency where the RE to which the PTRS is assigned is present in the spatial domain. It can be set to be obtained by performing filtering on a whitened matched filter and accumulating the result of filtering on the white matched filter.

According to various embodiments disclosed in this document, the at least one processor sets the first CFR estimate to be obtained based on REs to which the DMRS is assigned that are adjacent in the time domain to the RE to which the PTRS is assigned; , the REs to which the DMRS is assigned may be the two closest REs in the time domain from the RE to which the PTRS is assigned.

According to various embodiments disclosed in this document, the two REs to which the DMRS is allocated and the RE to which the PTRS is allocated may be located within a physical uplink shared channel (PUSCH) resource.

According to various embodiments disclosed in this document, the two REs to which the DMRS is assigned and the RE to which the PTRS is assigned may be located on the same subcarrier.

Claims (20)

In a method for a terminal to receive a phase tracking reference signal (PTRS) in a wireless communication system,
Obtaining a first CFR estimate in the RE to which the PTRS is assigned by performing linear interpolation based on two resource elements (REs) to which the demodulation reference signal (DMRS) is assigned;
Obtaining an estimate of the CPE angle difference for the RE to which the PTRS is assigned; and
A method comprising performing phase tracking of the RE to which the PTRS is assigned based on a second CFR estimate obtained by applying the estimate of the CPE angle difference to the first CFR estimate. In claim 1,
The estimated value of the CPE angle difference is,
filtering a received signal at a frequency where an RE to which the PTRS is assigned is present using a whitened matched filter in a spatial domain; and
A method obtained by accumulating filtered result values in the white matched filter. In claim 1,
Obtaining the first CFR estimate includes obtaining the first CFR estimate based on REs to which the DMRS is assigned that are adjacent in the time domain to the RE to which the PTRS is assigned,
The REs to which the DMRS is assigned are the two closest REs in the time domain from the RE to which the PTRS is assigned. In claim 1,
The two REs to which the DMRS is assigned and the RE to which the PTRS is assigned are located within a physical downlink shared channel (PDSCH) resource. In claim 1,
The method wherein the two REs to which the DMRS is assigned and the RE to which the PTRS is assigned are located on the same subcarrier. In a terminal that receives a phase tracking reference signal (PTRS) in a wireless communication system,
transceiver; and
Contains at least one processor,
The at least one processor,
Obtaining a first CFR estimate in the RE to which the PTRS is assigned by performing linear interpolation based on two resource elements (REs) to which a demodulation reference signal (DMRS) is assigned,
Obtain an estimate of the CPE angle difference for the RE to which the PTRS is assigned,
The UE is set to perform phase tracking of the RE to which the PTRS is assigned, based on a second CFR estimate obtained by applying the estimate of the CPE angle difference to the first CFR estimate. In claim 6,
The at least one processor,
The estimated value of the CPE angle difference is obtained by filtering the received signal at the frequency where the RE to which the PTRS is assigned is present using a whitened matched filter in the spatial domain,
A terminal set to be obtained by performing a step of accumulating filtered result values in the white matching filter. In claim 6,
The at least one processor,
The first CFR estimate is set to be obtained based on REs to which the DMRS is assigned adjacent to the RE to which the PTRS is assigned in the time domain,
The REs to which the DMRS is assigned are the two closest REs in the time domain from the RE to which the PTRS is assigned. In claim 6,
The two REs to which the DMRS is assigned and the RE to which the PTRS is assigned are located within a physical downlink shared channel (PDSCH) resource. In claim 6,
The two REs to which the DMRS is assigned and the RE to which the PTRS is assigned are located on the same subcarrier. In a method for a base station to receive a phase tracking reference signal (PTRS) in a wireless communication system,
Obtaining a first CFR estimate in the RE to which the PTRS is assigned by performing linear interpolation based on two resource elements (REs) to which the demodulation reference signal (DMRS) is assigned;
Obtaining an estimate of the CPE angle difference for the RE to which the PTRS is assigned; and
A method comprising performing phase tracking of the RE to which the PTRS is assigned based on a second CFR estimate obtained by applying the estimate of the CPE angle difference to the first CFR estimate. In claim 11,
The estimated value of the CPE angle difference is,
filtering a received signal at a frequency where an RE to which the PTRS is assigned is present using a whitened matched filter in a spatial domain; and
A method obtained by accumulating filtered result values in the white matched filter. In claim 11,
Obtaining the first CFR estimate includes obtaining the first CFR estimate based on REs to which the DMRS is assigned that are adjacent in the time domain to the RE to which the PTRS is assigned,
The REs to which the DMRS is assigned are the two closest REs in the time domain from the RE to which the PTRS is assigned. In claim 11,
The two REs to which the DMRS is assigned and the RE to which the PTRS is assigned are located within a physical uplink shared channel (PUSCH) resource. In claim 11,
The method wherein the two REs to which the DMRS is assigned and the RE to which the PTRS is assigned are located on the same subcarrier. In a base station that receives a phase tracking reference signal (PTRS) in a wireless communication system,
transceiver; and
Contains at least one processor,
The at least one processor,
By performing linear interpolation based on two resource elements (REs) to which a demodulation reference signal (DMRS) is assigned, a first CFR estimate is obtained in the RE to which the PTRS is assigned,
Obtain an estimate of the CPE angle difference for the RE to which the PTRS is assigned,
The base station is set to perform phase tracking of the RE to which the PTRS is assigned, based on a second CFR estimate obtained by applying the estimate of the CPE angle difference to the first CFR estimate. In claim 16,
The at least one processor,
The estimated value of the CPE angle difference is obtained by filtering the received signal at the frequency where the RE to which the PTRS is assigned is present using a whitened matched filter in the spatial domain,
A base station set to be obtained by performing a step of accumulating filtered result values in the white matched filter. In claim 16,
The at least one processor,
The first CFR estimate is set to be obtained based on REs to which the DMRS is assigned adjacent to the RE to which the PTRS is assigned in the time domain,
The REs to which the DMRS is assigned are the two closest REs in the time domain from the RE to which the PTRS is assigned. In claim 16,
The two REs to which the DMRS is assigned and the RE to which the PTRS is assigned are located within a physical uplink shared channel (PUSCH) resource. In claim 16,
The base station wherein the two REs to which the DMRS is assigned and the RE to which the PTRS is assigned are located on the same subcarrier.

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