Method and apparatus for transmitting phase tracking reference signal for phase noise compensation in OFDM system

Abstract

A method according to an embodiment of the present specification comprises the steps of: generating an orthogonal frequency division multiplexing (OFDM) signal; and transmitting the OFDM signal. The OFDM signal is generated on the basis of values of resource elements (REs) based on subcarrier indices. The values of the REs are based on information mapped to the REs. The information mapped to the REs is generated on the basis of the sum of i) data and ii) a phase tracking reference signal (PTRS) to which precoding related to discrete Fourier transform (DFT) has been applied.

Description

Method and apparatus for transmitting a phase tracking reference signal for phase noise compensation in an OFDM system

[0001] This specification relates to a method and apparatus for transmitting a phase tracking reference signal for phase noise compensation in an OFDM system.

[0002] Mobile communication systems were developed to provide voice services while ensuring user mobility. However, mobile communication systems have expanded their scope to include data services as well as voice. Currently, due to the explosive increase in traffic leading to resource shortages and users demanding higher-speed services, more advanced mobile communication systems are required.

[0003] The requirements for next-generation mobile communication systems largely include the ability to accommodate explosive data traffic, a dramatic increase in transmission rates per user, a significantly increased number of connected devices, very low end-to-end latency, and high energy efficiency. To achieve this, various technologies are being researched, such as dual connectivity, massive multiple input multiple output (MMIMO), in-band full duplex, non-orthogonal multiple access (NOMA), super wideband support, and device networking.

[0004] Meanwhile, 5G NR's PT-RS was introduced to address phase noise in the mmWave band. Since compensating for common phase error is sufficient in the mmWave band, PT-RS was designed with a structure capable of compensating for such error. Currently, inter-subcarrier interference caused by random phase noise cannot be compensated for through PT-RS.

[0005] However, 6G requires higher data transfer rates than 5G, and to achieve this, the use of the sub-THz band, which allows for a wider bandwidth than the mmWave band, is expected. Accordingly, as the impact of phase noise on system performance increases, a method to compensate for random phase noise is required.

[0006] The purpose of this specification is to propose a method for generating an OFDM signal capable of compensating for random phase noise.

[0007] The technical problems to be solved in this specification are not limited to those mentioned above, and other technical problems not mentioned will be clearly understood by those skilled in the art to which this specification belongs from the description below.

[0008] A method according to one embodiment of the present specification includes the steps of generating an Orthogonal Frequency Division Multiplexing (OFDM) signal and transmitting the OFDM signal.

[0009] The above OFDM signal is generated based on the values ​​of resource elements (RE) based on subcarrier indices.

[0010] The values ​​of the above REs are based on information mapped to the above REs.

[0011] The information mapped to the above REs is characterized by being generated based on the sum of i) data and ii) a Phase Tracking Reference Signal (PTRS) to which precoding related to the Discrete Fourier Transform (DFT) has been applied.

[0012] First information can be generated based on the Inverse Discrete Fourier Transform (IDFT) associated with the above OFDM signal. Based on the first information, first phase noise associated with the PTRS can be estimated. Based on the linear interpolation of the first phase noise, second phase noise associated with the data can be estimated.

[0013] The data can be decoded based on the DFT of the first information in which the second phase noise is compensated.

[0014] The above OFDM signal may be associated with an uplink channel or a downlink channel.

[0015] The transmission of the above ODFM signal may be a downlink transmission or an uplink transmission.

[0016] The information mapped to the REs can be generated by multiplying the PTRS to which the above DFT precoding has been applied by a boosting factor and then adding the above data.

[0017] The above boosting factor can be set based on control information or upper-level signaling.

[0018] A wireless device according to another embodiment of the present specification includes one or more transceivers, one or more processors for controlling the one or more transceivers, and one or more memories connected to the one or more processors for storing instructions.

[0019] The above instructions are characterized by enabling the wireless device to perform all steps of any one of the above methods based on execution by the one or more processors.

[0020] The above wireless device may be a base station or a terminal.

[0021] An apparatus according to another embodiment of the present specification comprises one or more memories and one or more processors functionally connected to the one or more memories. The one or more memories are characterized by storing instructions that cause the apparatus to perform all steps of any one of the methods based on execution by the one or more processors.

[0022] One or more non-transitory computer-readable storage media according to another embodiment of the present specification store instructions. The instructions, executable by one or more processors, are characterized by enabling a wireless device to perform all steps of any one of the methods.

[0023] Based on the embodiments of this specification, the OFDM signal generated can have phase noise estimated and compensated in the time domain. Accordingly, inter-carrier interference caused by random phase noise can be eliminated.

[0024] Furthermore, compared to conventional operation which can only compensate for common phase error (CPE) common to all frequency ranges within an OFDM symbol, phase noise occurring in the high-frequency band (THz band) can be compensated more effectively. In other words, the impact of phase noise in the high-frequency band on communication performance can be minimized.

[0025] The effects obtainable in this specification are not limited to those mentioned above, and other unmentioned effects will be clearly understood by those skilled in the art to which this specification belongs from the description below.

[0026] FIG. 1 is a drawing illustrating an example of a communication system applicable to the present specification.

[0027] FIG. 2 is a drawing illustrating an example of a wireless device that can be applied to the present specification.

[0028] FIG. 3 is a diagram illustrating a method for processing a transmission signal applicable to the present specification.

[0029] FIG. 4 is a drawing illustrating another example of a wireless device to which the present specification applies.

[0030] FIG. 5 is a drawing illustrating an example of a portable device to which the present specification applies.

[0031] FIG. 6 is a diagram illustrating physical channels applicable to the present specification and a signal transmission method using them.

[0032] Figure 7 is a figure showing an example of a communication structure that can be provided in a 6G system.

[0033] Figure 8 is a diagram illustrating an oscillator spectrum.

[0034] Figure 9 is a diagram illustrating the structure of an oscillator.

[0035] Figure 10 is a diagram illustrating the arrangement of PT-RS in the time domain.

[0036] FIG. 11 illustrates a PT-RS transmission structure according to an embodiment of the present specification.

[0037] FIG. 12 illustrates a PT-RS group according to an embodiment of the present specification.

[0038] FIG. 13 illustrates a phase noise compensation receiver according to an embodiment of the present specification.

[0039] Figure 14 illustrates phase noise and estimated phase noise.

[0040] FIG. 15 is a flowchart illustrating a method according to one embodiment of the present specification.

[0041] The following embodiments are combinations of the components and features of this specification in a predetermined form. Each component or feature may be considered optional unless otherwise explicitly stated. Each component or feature may be implemented in a form not combined with other components or features. Additionally, some components and / or features may be combined to constitute the embodiments of this specification. The order of operations described in the embodiments of this specification may be changed. Some components or features of any embodiment may be included in another embodiment, or may be replaced with corresponding components or features of another embodiment.

[0042] In the description of the drawings, procedures or steps that could obscure the gist of the specification have not been described, nor have procedures or steps that are understandable to those skilled in the art been described.

[0043] Throughout the specification, when a part is described as "comprising" or "including" a component, this means that, unless specifically stated otherwise, it does not exclude other components but may include additional components. Furthermore, terms such as "...part," "...unit," and "module" as used in the specification refer to a unit that performs at least one function or operation, and this may be implemented in hardware, software, or a combination of hardware and software. Additionally, "one (a or an)," "one," "the," and similar related terms may be used in the context describing this specification (particularly in the context of the following claims) to include both singular and plural forms, unless otherwise indicated in this specification or clearly contradicted by the context.

[0044] The embodiments of this specification have been described with a focus on the data transmission and reception relationship between a base station and a mobile station. Here, the base station refers to a terminal node of a network that communicates directly with a mobile station. Specific operations described herein as being performed by a base station may, in some cases, be performed by an upper node of the base station.

[0045] That is, in a network consisting of multiple network nodes including a base station, various operations performed for communication with a mobile station may be performed by the base station or other network nodes other than the base station. In this case, 'base station' may be replaced by terms such as fixed station, Node B, eNB (eNode B), gNB (gNode B), ng-eNB, advanced base station (ABS), or access point.

[0046] Additionally, in the embodiments of this specification, the term terminal may be replaced with terms such as user equipment (UE), mobile station (MS), subscriber station (SS), mobile subscriber station (MSS), mobile terminal, or advanced mobile station (AMS).

[0047] Furthermore, the transmitting end refers to a fixed and / or mobile node that provides data or voice services, and the receiving end refers to a fixed and / or mobile node that receives data or voice services. Therefore, in the case of the uplink, a mobile station can be the transmitting end and a base station can be the receiving end. Similarly, in the case of the downlink, a mobile station can be the receiving end and a base station can be the transmitting end.

[0048] The embodiments of this specification may be supported by standard documents disclosed in at least one of the wireless access systems, such as IEEE 802.xx systems, 3GPP (3rd Generation Partnership Project) systems, 3GPP LTE (Long Term Evolution) systems, 3GPP 5G (5th generation) NR (New Radio) systems and 3GPP2 systems, and in particular, the embodiments of this specification may be supported by the documents 3GPP TS (technical specification) 38.211, 3GPP TS 38.212, 3GPP TS 38.213, 3GPP TS 38.321 and 3GPP TS 38.331.

[0049] In addition, the embodiments of this specification may be applied to other wireless access systems and are not limited to the systems described above. For example, they may be applicable to systems applied after the 3GPP 5G NR system and are not limited to specific systems.

[0050] That is, obvious steps or parts not described in the embodiments of this specification may be described by referring to the aforementioned documents. Additionally, all terms disclosed in this specification may be explained by the aforementioned standard documents.

[0051] Hereinafter, preferred embodiments according to the present specification will be described in detail with reference to the accompanying drawings. The detailed description disclosed below, together with the accompanying drawings, is intended to describe exemplary embodiments of the present specification and is not intended to represent the only embodiment in which the technical configuration of the present specification can be implemented.

[0052] Additionally, specific terms used in the embodiments of this specification are provided to aid in understanding this specification, and the use of such specific terms may be modified in other forms without departing from the technical spirit of this specification.

[0053] The following technology can be applied to various wireless access systems such as CDMA (code division multiple access), FDMA (frequency division multiple access), TDMA (time division multiple access), OFDMA (orthogonal frequency division multiple access), and SC-FDMA (single carrier frequency division multiple access).

[0054] For the sake of clarity in the following description, the explanation is based on 3GPP communication systems (e.g., LTE, NR, etc.), but the technical concept of the present invention is not limited thereto. LTE may refer to technology from 3GPP TS 36.xxx Release 8 onwards. Specifically, LTE technology from 3GPP TS 36.xxx Release 10 onwards is referred to as LTE-A, and LTE technology from 3GPP TS 36.xxx Release 13 onwards may be referred to as LTE-A pro. 3GPP NR may refer to technology from TS 38.xxx Release 15 onwards. 3GPP 6G may refer to technology from TS Release 17 and / or Release 18 onwards. "xxx" indicates a standard document detail number. LTE / NR / 6G may be collectively referred to as 3GPP systems.

[0055] Regarding the background technology, terms, abbreviations, etc. used in this specification, reference may be made to matters described in standard documents published prior to the present invention. For example, reference may be made to standard documents 36.xxx and 38.xxx.

[0056] Communication systems applicable to the present specification

[0057] Although not limited thereto, the various descriptions, functions, procedures, proposals, methods, and / or flowcharts of operation disclosed in this specification may be applied to various fields requiring wireless communication / connection (e.g., 5G) between devices.

[0058] Examples are provided in more detail below with reference to the drawings. In the following drawings and descriptions, the same reference numerals may represent the same or corresponding hardware blocks, software blocks, or function blocks unless otherwise described.

[0059] FIG. 1 is a drawing illustrating an example of a communication system to which the present specification applies. Referring to FIG. 1, the communication system (100) to which the present specification applies includes a wireless device, a base station, and a network. Here, a wireless device refers to a device that performs communication using wireless access technology (e.g., 5G NR, LTE) and may be referred to as a communication / wireless / 5G device. Although not limited thereto, a wireless device may include a robot (100a), a vehicle (100b-1, 100b-2), an XR (extended reality) device (100c), a hand-held device (100d), a home appliance (100e), an IoT (Internet of Thing) device (100f), and an AI (artificial intelligence) device / server (100g). For example, a vehicle may include a vehicle equipped with wireless communication capabilities, an autonomous vehicle, a vehicle capable of performing inter-vehicle communication, etc. Here, the vehicle (100b-1, 100b-2) may include an unmanned aerial vehicle (UAV) (e.g., a drone). The XR device (100c) includes an augmented reality (AR) / virtual reality (VR) / mixed reality (MR) device and may be implemented in the form of a head-mounted device (HMD), a head-up display (HUD) equipped in a vehicle, a television, a smartphone, a computer, a wearable device, a home appliance, digital signage, a vehicle, a robot, etc. The portable device (100d) may include a smartphone, a smart pad, a wearable device (e.g., a smartwatch, smart glasses), a computer (e.g., a laptop, etc.). The home appliance (100e) may include a TV, a refrigerator, a washing machine, etc. The IoT device (100f) may include a sensor, a smart meter, etc.For example, the base station (120) and network (130) may also be implemented as wireless devices, and a specific wireless device (120a) may act as a base station / network node for other wireless devices.

[0060] Wireless devices (100a to 100f) can be connected to a network (130) through a base station (120). AI technology may be applied to the wireless devices (100a to 100f), and the wireless devices (100a to 100f) can be connected to an AI server (100g) through the network (130). The network (130) can be configured using a 3G network, a 4G (e.g., LTE) network, or a 5G (e.g., NR) network. The wireless devices (100a to 100f) may communicate with each other through the base station (120) / network (130), but they may also communicate directly (e.g., sidelink communication) without going through the base station (120) / network (130). For example, vehicles (100b-1, 100b-2) can communicate directly (e.g., V2V (vehicle to vehicle) / V2X (vehicle to everything) communication). Also, IoT devices (100f) (e.g., sensors) can communicate directly with other IoT devices (e.g., sensors) or other wireless devices (100a to 100f).

[0061] Wireless communication / connection (150a, 150b, 150c) can be established between wireless devices (100a~100f) / base station (120) and between base station (120) / base station (120). Here, wireless communication / connection can be established through various wireless access technologies (e.g., 5G NR), such as uplink / downlink communication (150a), sidelink communication (150b) (or D2D communication), and communication between base stations (150c) (e.g., relay, IAB (integrated access backhaul)). Through wireless communication / connection (150a, 150b, 150c), wireless devices and base stations / wireless devices, and base stations and base stations can transmit / receive wireless signals to / from each other. For example, wireless communication / connection (150a, 150b, 150c) can transmit / receive signals through various physical channels. To this end, based on the various proposals of this specification, at least some of the following may be performed: a process for setting various configuration information for transmitting / receiving wireless signals, a process for various signal processing (e.g., channel encoding / decoding, modulation / demodulation, resource mapping / demapping, etc.), a resource allocation process, etc.

[0062] Communication systems applicable to the present specification

[0063] FIG. 2 is a drawing illustrating an example of a wireless device that can be applied to the present specification.

[0064] Referring to FIG. 2, the first wireless device (200a) and the second wireless device (200b) can transmit and receive wireless signals through various wireless access technologies (e.g., LTE, NR). Here, {the first wireless device (200a), the second wireless device (200b)} may correspond to {the wireless device (100x), the base station (120)} and / or {the wireless device (100x), the wireless device (100x)} of FIG. 1.

[0065] The first wireless device (200a) includes one or more processors (202a) and one or more memories (204a), and may additionally include one or more transceivers (206a) and / or one or more antennas (208a). The processor (202a) controls the memory (204a) and / or transceivers (206a) and may be configured to implement the descriptions, functions, procedures, proposals, methods and / or sequences of operation disclosed herein. For example, the processor (202a) may process information within the memory (204a) to generate a first information / signal and then transmit a wireless signal containing the first information / signal through the transceiver (206a). Additionally, the processor (202a) may receive a wireless signal containing a second information / signal through the transceiver (206a) and then store information obtained from the signal processing of the second information / signal in the memory (204a). Memory (204a) may be connected to the processor (202a) and may store various information related to the operation of the processor (202a). For example, memory (204a) may store software code including instructions for performing some or all of the processes controlled by the processor (202a) or for performing the descriptions, functions, procedures, proposals, methods, and / or sequences of operation disclosed in this specification. Here, the processor (202a) and memory (204a) may be part of a communication modem / circuit / chip designed to implement wireless communication technology (e.g., LTE, NR). A transceiver (206a) may be connected to the processor (202a) and may transmit and / or receive wireless signals through one or more antennas (208a). The transceiver (206a) may include a transmitter and / or receiver. The transceiver (206a) may be combined with an RF (radio frequency) unit. In this specification, a wireless device may refer to a communication modem / circuit / chip.

[0066] The second wireless device (200b) includes one or more processors (202b) and one or more memories (204b), and may additionally include one or more transceivers (206b) and / or one or more antennas (208b). The processor (202b) controls the memory (204b) and / or transceivers (206b) and may be configured to implement the descriptions, functions, procedures, proposals, methods and / or sequences of operation disclosed herein. For example, the processor (202b) may process information within the memory (204b) to generate a third information / signal and then transmit a wireless signal containing the third information / signal through the transceiver (206b). Additionally, the processor (202b) may receive a wireless signal containing a fourth information / signal through the transceiver (206b) and then store information obtained from the signal processing of the fourth information / signal in the memory (204b). The memory (204b) may be connected to the processor (202b) and may store various information related to the operation of the processor (202b). For example, the memory (204b) may store software code including instructions for performing some or all of the processes controlled by the processor (202b) or for performing the descriptions, functions, procedures, proposals, methods, and / or sequence diagrams of operation disclosed in this specification. Here, the processor (202b) and the memory (204b) may be part of a communication modem / circuit / chip designed to implement wireless communication technology (e.g., LTE, NR). The transceiver (206b) may be connected to the processor (202b) and may transmit and / or receive wireless signals through one or more antennas (208b). The transceiver (206b) may include a transmitter and / or receiver. The transceiver (206b) may be used in combination with an RF unit. In this specification, a wireless device may refer to a communication modem / circuit / chip.

[0067] Hereinafter, hardware elements of the wireless device (200a, 200b) will be described in more detail. Although not limited thereto, one or more protocol layers may be implemented by one or more processors (202a, 202b). For example, one or more processors (202a, 202b) may implement one or more layers (e.g., functional layers such as PHY (physical), MAC (media access control), RLC (radio link control), PDCP (packet data convergence protocol), RRC (radio resource control), and SDAP (service data adaptation protocol). One or more processors (202a, 202b) may generate one or more PDUs (Protocol Data Units) and / or one or more SDUs (service data units) according to the descriptions, functions, procedures, proposals, methods, and / or flowcharts of operation disclosed herein. One or more processors (202a, 202b) may generate messages, control information, data, or information according to the descriptions, functions, procedures, proposals, methods, and / or flowcharts of operation disclosed in this specification. One or more processors (202a, 202b) may generate a signal (e.g., baseband signal) including a PDU, SDU, message, control information, data, or information according to the functions, procedures, proposals, and / or methods disclosed in this specification and provide it to one or more transceivers (206a, 206b). One or more processors (202a, 202b) may receive a signal (e.g., baseband signal) from one or more transceivers (206a, 206b) and may obtain a PDU, SDU, message, control information, data, or information according to the descriptions, functions, procedures, proposals, methods, and / or flowcharts of operation disclosed in this specification.

[0068] One or more processors (202a, 202b) may be referred to as a controller, microcontroller, microprocessor, or microcomputer. One or more processors (202a, 202b) may be implemented by hardware, firmware, software, or a combination thereof. For example, one or more application-specific integrated circuits (ASICs), one or more digital signal processors (DSPs), one or more digital signal processing devices (DSPDs), one or more programmable logic devices (PLDs), or one or more field programmable gate arrays (FPGAs) may be included in one or more processors (202a, 202b). Descriptions, functions, procedures, proposals, methods, and / or flowcharts disclosed herein may be implemented using firmware or software, and the firmware or software may be implemented to include modules, procedures, functions, etc. Firmware or software configured to perform the descriptions, functions, procedures, proposals, methods, and / or operation sequences disclosed in this specification may be included in one or more processors (202a, 202b) or stored in one or more memories (204a, 204b) and driven by one or more processors (202a, 202b). The descriptions, functions, procedures, proposals, methods, and / or operation sequences disclosed in this specification may be implemented using firmware or software in the form of code, instructions, and / or sets of instructions.

[0069] One or more memories (204a, 204b) may be connected to one or more processors (202a, 202b) and may store various forms of data, signals, messages, information, programs, codes, instructions, and / or commands. One or more memories (204a, 204b) may be composed of ROM (read-only memory), RAM (random access memory), EPROM (erasable programmable read-only memory), flash memory, hard drives, registers, cache memory, computer-readable storage media, and / or combinations thereof. One or more memories (204a, 204b) may be located inside and / or outside of one or more processors (202a, 202b). Additionally, one or more memories (204a, 204b) may be connected to one or more processors (202a, 202b) through various technologies such as wired or wireless connections.

[0070] One or more transceivers (206a, 206b) may transmit user data, control information, wireless signals / channels, etc., as mentioned in the methods and / or operation flowcharts, etc., of this specification to one or more other devices. One or more transceivers (206a, 206b) may receive user data, control information, wireless signals / channels, etc., as mentioned in the descriptions, functions, procedures, proposals, methods and / or operation flowcharts, etc., disclosed in this specification from one or more other devices. For example, one or more transceivers (206a, 206b) may be connected to one or more processors (202a, 202b) and may transmit and receive wireless signals. For example, one or more processors (202a, 202b) may control one or more transceivers (206a, 206b) to transmit user data, control information, or wireless signals to one or more other devices. Additionally, one or more processors (202a, 202b) may control one or more transceivers (206a, 206b) to receive user data, control information, or wireless signals from one or more other devices. Additionally, one or more transceivers (206a, 206b) may be connected to one or more antennas (208a, 208b), and one or more transceivers (206a, 206b) may be configured to transmit and receive user data, control information, wireless signals / channels, etc., as described in the descriptions, functions, procedures, proposals, methods, and / or flowcharts of operation disclosed herein through one or more antennas (208a, 208b). In this specification, one or more antennas may be a plurality of physical antennas or a plurality of logical antennas (e.g., antenna ports). One or more transceivers (206a, 206b) can convert the received wireless signal / channel, etc. from an RF band signal to a baseband signal in order to process the received user data, control information, wireless signal / channel, etc. using one or more processors (202a, 202b).One or more transceivers (206a, 206b) can convert user data, control information, wireless signals / channels, etc. processed using one or more processors (202a, 202b) from baseband signals to RF band signals. To this end, one or more transceivers (206a, 206b) may include (analog) oscillators and / or filters.

[0071] FIG. 3 is a diagram illustrating a method for processing a transmission signal applicable to the present specification. For example, the transmission signal may be processed by a signal processing circuit. In this case, the signal processing circuit (300) may include a scrambler (310), a modulator (320), a layer mapper (330), a precoder (340), a resource mapper (350), and a signal generator (360). In this case, for example, the operation / function of FIG. 3 may be performed in the processor (202a, 202b) and / or transceiver (206a, 206b) of FIG. 2. Also, for example, the hardware element of FIG. 3 may be implemented in the processor (202a, 202b) and / or transceiver (206a, 206b) of FIG. 2. For example, blocks 310 to 350 may be implemented in the processor (202a, 202b) of FIG. 2, and block 360 may be implemented in the transceiver (206a, 206b) of FIG. 2, but are not limited to the above-described embodiment.

[0072] A codeword can be converted into a wireless signal through the signal processing circuit (300) of FIG. 3. Here, the codeword is an encoded bit sequence of an information block. The information block may include a transmission block (e.g., UL-SCH transmission block, DL-SCH transmission block). The wireless signal may be transmitted through various physical channels (e.g., PUSCH, PDSCH) of FIG. 6. Specifically, the codeword can be converted into a scrambled bit sequence by a scrambler (310). The scrambled sequence used for scrambling is generated based on an initialization value, which may include ID information of a wireless device, etc. The scrambled bit sequence may be modulated into a modulation symbol sequence by a modulator (320). The modulation method may include pi / 2-BPSK (pi / 2-binary phase shift keying), m-PSK (m-phase shift keying), m-QAM (m-quadrature amplitude modulation), etc.

[0073] A complex modulation symbol sequence can be mapped to one or more transmission layers by a layer mapper (330). The modulation symbols of each transmission layer can be mapped to the corresponding antenna port(s) by a precoder (340) (precoding). The output z of the precoder (340) can be obtained by multiplying the output y of the layer mapper (330) by an N*M precoding matrix W, where N is the number of antenna ports and M is the number of transmission layers. Here, the precoder (340) can perform precoding after performing transform precoding (e.g., a discrete Fourier transform (DFT)) on the complex modulation symbols. Alternatively, the precoder (340) can perform precoding without performing transform precoding.

[0074] A resource mapper (350) can map the modulation symbols of each antenna port to a time-frequency resource. The time-frequency resource may include multiple symbols (e.g., CP-OFDMA symbols, DFT-s-OFDMA symbols) in the time domain and multiple subcarriers in the frequency domain. A signal generator (360) generates a radio signal from the mapped modulation symbols, and the generated radio signal can be transmitted to another device through each antenna. To this end, the signal generator (360) may include an inverse fast Fourier transform (IFFT) module, a cyclic prefix (CP) inserter, a digital-to-analog converter (DAC), a frequency uplink converter, etc.

[0075] The signal processing process for a received signal in a wireless device can be configured as the inverse of the signal processing process (310–360) of FIG. 3. For example, a wireless device (e.g., 200a, 200b of FIG. 2) can receive a wireless signal from the outside through an antenna port / transceiver. The received wireless signal can be converted into a baseband signal through a signal restorer. To this end, the signal restorer may include a frequency downlink converter, an analog-to-digital converter (ADC), a CP remover, and a fast Fourier transform (FFT) module. Subsequently, the baseband signal can be restored into a codeword through a resource de-mapper process, a postcoding process, a demodulation process, and a de-scrambling process. The codeword can be restored into the original information block through decoding. Accordingly, a signal processing circuit (not shown) for a received signal may include a signal restorer, a resource de-mapper, a postcoder, a demodulator, a de-scrambler, and a decoder.

[0076] Wireless device structure applicable to the present specification

[0077] FIG. 4 is a drawing illustrating another example of a wireless device to which the present specification applies.

[0078] Referring to FIG. 4, the wireless device (400) corresponds to the wireless device (200a, 200b) of FIG. 2 and may be composed of various elements, components, units / parts, and / or modules. For example, the wireless device (400) may include a communication unit (410), a control unit (420), a memory unit (430), and additional elements (440). The communication unit may include a communication circuit (412) and transceiver(s) (414). For example, the communication circuit (412) may include one or more processors (202a, 202b) and / or one or more memories (204a, 204b) of FIG. 2. For example, the transceiver(s) (414) may include one or more transceivers (206a, 206b) and / or one or more antennas (208a, 208b) of FIG. 2. The control unit (420) is electrically connected to the communication unit (410), the memory unit (430), and additional elements (440) and controls the general operation of the wireless device. For example, the control unit (420) may control the electrical / mechanical operation of the wireless device based on a program / code / command / information stored in the memory unit (430). Additionally, the control unit (420) may transmit information stored in the memory unit (430) to an external (e.g., another communication device) via a wireless / wired interface through the communication unit (410), or store information received from an external (e.g., another communication device) via a wireless / wired interface through the communication unit (410) in the memory unit (430).

[0079] The additional element (440) can be configured in various ways depending on the type of wireless device. For example, the additional element (440) may include at least one of a power unit / battery, an input / output unit, a driving unit, and a computing unit. Although not limited thereto, the wireless device (400) may be implemented in the form of a robot (Fig. 1, 100a), a vehicle (Fig. 1, 100b-1, 100b-2), an XR device (Fig. 1, 100c), a portable device (Fig. 1, 100d), a home appliance (Fig. 1, 100e), an IoT device (Fig. 1, 100f), a digital broadcasting terminal, a hologram device, a public safety device, an MTC device, a medical device, a fintech device (or financial device), a security device, a climate / environment device, an AI server / device (Fig. 1, 140), a base station (Fig. 1, 120), a network node, etc. Wireless devices can be used in a movable or fixed location depending on the use—e.g., service.

[0080] In FIG. 4, various elements, components, units / parts, and / or modules within the wireless device (400) may be entirely interconnected via a wired interface, or at least partially connected via a communication unit (410). For example, within the wireless device (400), the control unit (420) and the communication unit (410) may be connected via a wire, and the control unit (420) and the first unit (e.g., 430, 440) may be connected wirelessly via the communication unit (410). Additionally, each element, component, unit / part, and / or module within the wireless device (400) may include one or more additional elements. For example, the control unit (420) may be composed of one or more sets of processors. For example, the control unit (420) may be composed of a set of a communication control processor, an application processor, an electronic control unit (ECU), a graphics processing processor, a memory control processor, etc. As another example, the memory unit (430) may be composed of RAM, DRAM (dynamic RAM), ROM, flash memory, volatile memory, non-volatile memory and / or a combination thereof.

[0081] Mobile devices to which this specification applies

[0082] FIG. 5 is a drawing illustrating an example of a portable device to which the present specification applies.

[0083] FIG. 5 illustrates a portable device to which the present specification applies. The portable device may include a smartphone, a smartpad, a wearable device (e.g., a smart watch, smart glasses), a portable computer (e.g., a laptop, etc.). The portable device may be referred to as an MS (mobile station), UT (user terminal), MSS (mobile subscriber station), SS (subscriber station), AMS (advanced mobile station), or WT (wireless terminal).

[0084] Referring to FIG. 5, the portable device (500) may include an antenna unit (508), a communication unit (510), a control unit (520), a memory unit (530), a power supply unit (540a), an interface unit (540b), and an input / output unit (540c). The antenna unit (508) may be configured as part of the communication unit (510). Blocks 510 to 530 / 540a to 540c correspond to blocks 410 to 430 / 440 of FIG. 4, respectively.

[0085] The communication unit (510) can transmit and receive signals (e.g., data, control signals, etc.) with other wireless devices and base stations. The control unit (520) can control the components of the portable device (500) to perform various operations. The control unit (520) may include an application processor (AP). The memory unit (530) can store data / parameters / programs / code / commands required for the operation of the portable device (500). Additionally, the memory unit (530) can store input / output data / information, etc. The power supply unit (540a) supplies power to the portable device (500) and may include wired / wireless charging circuits, batteries, etc. The interface unit (540b) can support the connection between the portable device (500) and other external devices. The interface unit (540b) may include various ports (e.g., audio input / output ports, video input / output ports) for connection with external devices. The input / output unit (540c) can receive or output video information / signals, audio information / signals, data, and / or information input from a user. The input / output unit (540c) may include a camera, a microphone, a user input unit, a display unit (540d), a speaker and / or a haptic module, etc.

[0086] For example, in the case of data communication, the input / output unit (540c) acquires information / signals (e.g., touch, text, voice, image, video) input by the user, and the acquired information / signals can be stored in the memory unit (530). The communication unit (510) converts the information / signals stored in the memory into wireless signals and can directly transmit the converted wireless signals to another wireless device or to a base station. Additionally, the communication unit (510) can receive wireless signals from another wireless device or base station and then restore the received wireless signals to their original information / signals. The restored information / signals are stored in the memory unit (530) and then can be output in various forms (e.g., text, voice, image, video, haptic) through the input / output unit (540c).

[0087] Physical channels and general signal transmission

[0088] In a wireless access system, a terminal can receive information from a base station via a downlink (DL) and transmit information to a base station via an uplink (UL). The information transmitted and received by the base station and the terminal includes general data information and various control information, and various physical channels exist depending on the type and purpose of the information they transmit and receive.

[0089] FIG. 6 is a diagram illustrating physical channels applicable to the present specification and a signal transmission method using them.

[0090] When a terminal is turned on again after being turned off, or when it newly enters a cell, it performs initial cell search operations, such as synchronizing with the base station, in step S611. To do this, the terminal receives the primary synchronization channel (P-SCH) and secondary synchronization channel (S-SCH) from the base station to synchronize with the base station and obtain information such as the cell ID.

[0091] Subsequently, the terminal can obtain in-cell broadcast information by receiving a physical broadcast channel (PBCH) signal from the base station. Meanwhile, during the initial cell search phase, the terminal can check the downlink channel status by receiving a Downlink Reference Signal (DL RS). After completing the initial cell search, the terminal can obtain more specific system information by receiving the physical downlink control channel (PDCCH) and the physical downlink shared channel (PDSCH) based on the physical downlink control channel information in step S612.

[0092] Subsequently, the terminal may perform a random access procedure, such as steps S613 through S616, to complete the connection to the base station. To this end, the terminal transmits a preamble through a physical random access channel (PRACH) (S613) and receives a random access response (RAR) for the preamble through a physical downlink control channel and a corresponding physical downlink shared channel (S614). The terminal transmits a physical uplink shared channel (PUSCH) using scheduling information within the RAR (S615) and performs a contention resolution procedure, such as receiving a physical downlink control channel signal and a corresponding physical downlink shared channel signal (S616).

[0093] A terminal that has performed the procedure described above may subsequently perform the reception of a physical downlink control channel signal and / or a physical downlink shared channel signal (S617) and the transmission of a physical uplink shared channel (PUSCH) signal and / or a physical uplink control channel (PUCCH) signal (S618) as a general uplink / downlink signal transmission procedure.

[0094] Control information transmitted by a terminal to a base station is collectively referred to as uplink control information (UCI). UCI includes HARQ-ACK / NACK (hybrid automatic repeat and request acknowledgment / negative-ACK), SR (scheduling request), CQI (channel quality indication), PMI (precoding matrix indication), RI (rank indication), BI (beam indication) information, etc. In this case, UCI is generally transmitted periodically via PUCCH, but depending on the embodiment (e.g., when control information and traffic data need to be transmitted simultaneously), it may be transmitted via PUSCH. Additionally, the terminal may transmit UCI non-periodically via PUSCH in response to a request or instruction from the network.

[0095] Figure 7 is a figure showing an example of a communication structure that can be provided in a 6G system.

[0096] 6G systems are expected to have 50 times higher simultaneous wireless connectivity than 5G wireless communication systems. URLLC, a key feature of 5G, will become an even more dominant technology in 6G communication by providing end-to-end latency of less than 1ms. Unlike the frequently used area spectrum efficiency, 6G systems will exhibit significantly superior volume spectrum efficiency. 6G systems can provide very long battery life and advanced battery technologies for energy harvesting, meaning mobile devices in 6G systems will not require separate charging. New network characteristics in 6G may include the following.

[0097] - Satellite Integrated Network: 6G is expected to be integrated with satellites to provide a global mobile population. Integrating terrestrial, satellite, and airborne networks into a single wireless communication system is crucial for 6G.

[0098] - Connected Intelligence: Unlike previous generations of wireless communication systems, 6G is innovative and will update wireless evolution from "connected things" to "connected intelligence." AI can be applied at each stage of the communication process (or at each step of the signal processing described below).

[0099] - Seamless integration of wireless information and energy transfer: 6G wireless networks will transfer power to charge the batteries of devices such as smartphones and sensors. Therefore, wireless information and energy transfer (WIET) will be integrated.

[0100] - Ubiquitous Super 3D Connectivity: Connectivity to the network and core network functions of drones and very low Earth orbit satellites will create Super 3D connectivity in 6G ubiquitous.

[0101] Some general requirements regarding the new network characteristics of 6G mentioned above may be as follows.

[0102] - Small cell networks: The idea of ​​small cell networks was introduced to improve the quality of received signals in cellular systems as a result of increased throughput, energy efficiency, and spectrum efficiency. Consequently, small cell networks are an essential feature of communication systems for 5G and beyond 5G (5GB). Therefore, 6G communication systems also adopt the characteristics of small cell networks.

[0103] - Ultra-dense heterogeneous network: Ultra-dense heterogeneous networks will be another important characteristic of 6G communication systems. Multi-tier networks composed of heterogeneous networks improve overall QoS and reduce costs.

[0104] - High-capacity backhaul: Backhaul connections are characterized as high-capacity backhaul networks to support high-volume traffic. High-speed fiber optics and free-space optics (FSO) systems can be possible solutions to this problem.

[0105] - Radar technology integrated with mobile technology: High-precision localization (or location-based services) through communication is one of the functions of 6G wireless communication systems. Therefore, radar systems will be integrated with 6G networks.

[0106] - Softwarization and virtualization: Softwarization and virtualization are two important features that form the basis of the design process in 5GB networks to ensure flexibility, reconfigurability, and programmability. Additionally, billions of devices can be shared across a shared physical infrastructure.

[0107] The symbols / abbreviations / terms used in this specification are as follows.

[0108] - PT-RS: Phase Tracking Reference Signal

[0109] - DFT: Discrete Fourier Transform

[0110] - IDFT: Inverse Discrete Fourier Transform

[0111] - FFT: Fast Fourier Transform

[0112] - IFFT: Inverse Fast Fourier Transform

[0113] - PN: Phase Noise

[0114] - VCO: Voltage Controlled Oscillator

[0115] - OFDM: Orthogonal Frequency Division Multiplexing

[0116] - CPE: Common Phase Error

[0117] - ICI: Inter-Carrier Interference

[0118] - DMRS: Demodulation Reference Signal

[0119] - SNR: Signal-to-Noise Ratio

[0120] This specification relates to a method for transmitting a new Phase Tracking Reference Signal (PT-RS) capable of compensating for random phase noise in OFDM. In particular, it presents a method for estimating and compensating for random phase noise in the time domain at an OFDM receiver by precoding the PT-RS using the Discrete Fourier Transform (DFT) and superimposing it onto the data for transmission.

[0121] The background technology related to the embodiments of the present specification will be described below with reference to FIGS. 8 to 10.

[0122] Phase Noise >

[0123] Figure 8 is a diagram illustrating an oscillator spectrum.

[0124] Ideally, an oscillator is a sine wave generator that has only a single pure frequency component (Fig. 8(a)). However, as can be seen in Fig. 8(b), the output signal of an actual oscillator appears as a frequency-modulated version of the ideal sine wave with noise. These additional frequency components, other than the target frequency of the oscillator, cause arbitrary phase fluctuations in the signal modulated by the oscillator. This is called phase noise (PN).

[0125] Figure 9 is a diagram illustrating the structure of an oscillator.

[0126] Specifically, the oscillator structure according to FIG. 9 includes a phase / frequency detector (PFD), a charge pump (CP), a low pass filter (LPF), a voltage-controlled oscillator (VCO), and a divider (N).

[0127] In an oscillator structure, the sources of phase noise are the reference clock signal Ref(t) and the VCO. As the frequency of the signal to be generated by the oscillator increases, the value of Divider N increases; consequently, the loop bandwidth expands, leading to significant amplification of the VCO's phase noise. For this reason, the magnitude of phase noise increases with higher carrier frequencies used in communication, becoming a major cause of communication performance degradation.

[0128] Phase noise is a multiplication noise component with a constant envelope that varies arbitrarily in the time domain. It can be expressed as follows. The OFDM received signal r[n], which passes through channel h[n] and is affected by phase noise, is given by the following Equation 1.

[0129]

[0130] In mathematical formula 1, represents the convolution operation, and x[n] is the transmitted signal, and is phase noise, h[n] is channel impulse response, and w[n] is additive white noise.

[0131] The OFDM demodulated signal R[k] with N-point DFT applied to the received signal r[n] is given by the following Equation 2.

[0132]

[0133] In mathematical formula 2, represents an N-point circular convolution operation, and is an N-point DFT applied And, X[k] is x[n] with N-point DFT applied, and H[k] is h[n] with N-point DFT applied, and w[n] is the result of N-point DFT.

[0134] Phase noise Due to the low-pass characteristics of the phase noise, it has a limited number of significant components around the center frequency. If u is the single-sided spectral width of the phase noise, the OFDM demodulated signal at subcarrier k is given by the following Equation 3.

[0135]

[0136] In mathematical formula 3, Is And, is additive white noise and It is a residual component resulting from convolution in the region extending beyond. is the Common Phase Error (CPE) component. The above CPE component is a phase shift value commonly applied to all subcarriers due to phase noise. Also is an inter-carrier interference component. The above inter-carrier interference component is caused by phase noise (random phase noise) that changes within one OFDM symbol interval.

[0137] < Conventional Phase Noise Estimation and Compensation Methods >

[0138] With the support of the mmWave band in 5G NR, the carrier frequency used for communication has increased, leading to a greater impact of phase noise on communication performance. In the FR2 (frequency Range 2, 24.25 ~ 52.6 GHz) band corresponding to mmWave, Common Phase Error (CPE) was the primary cause of performance degradation due to phase noise. To compensate for CPE, the Phase Tracking Reference Signal (PT-RS) was introduced in the 5G NR standard. The PT-RS will be explained below with reference to Figure 10.

[0139] Figure 10 is a diagram illustrating the arrangement of PT-RS in the time domain.

[0140] In NR, time domain densities (or time densities) of 1, 2, and 4 are supported for PT-RS. Referring to FIG. 10, when the time density is 1 (PTRS TD-1), PT-RS is assigned to consecutive symbols excluding the symbol where DMRS is transmitted. When the time density is 2 (PTRS TD-2), PT-RS is assigned to one symbol every 2 symbols. When the time density is 4 (PTRS TD-4), PT-RS is assigned to one symbol every 4 symbols.

[0141] Using this PT-RS, a receiver (e.g., a terminal or base station) can estimate the common phase noise (CPE) within a symbol as shown in the following Equation 4.

[0142]

[0143] In mathematical formula 4, Is And, is a channel estimated based on PT-RS, and is a channel estimated based on DMRS, and is the number of PT-RS resource elements in the OFDM symbol.

[0144] In NR, the antenna port of the PT-RS is quasi-colocated with the antenna port of the DMRS with the lowest index among the DMRSs assigned to the PDSCH. The DMRS in Equation 4 has a quasi-colocated relationship with the PT-RS and QCL Type-A and QCL Type-D.

[0145] QCL Type-A means that it underwent the same Doppler shift, Doppler spread, mean delay, and delay spread, and QCL Type-D means that it was transmitted on the same beam. In Equation 4, it can be assumed that DMRS and PT-RS underwent the same transmission channel. Therefore, by compensating the channel estimated based on DMRS for the channel estimated based on PT-RS, only the phase noise component remains.

[0146] As described above, while common phase error (CPE) within a single OFDM symbol can be estimated using the existing 5G NR PT-RS, random phase noise that changes even within a single OFDM symbol in the time domain cannot be estimated or compensated.

[0147] To achieve the goal of 6G technology, which is to improve data transmission rates by up to 10 times compared to 5G, an increase in transmission bandwidth is inevitable. To secure the necessary transmission bandwidth, it is expected that higher frequency bands than existing ones, such as sub-THz or THz bands, will need to be used. In these higher frequency bands, performance degradation caused by inter-carrier interference (ICI) as well as CPE becomes prominent.

[0148] The simplest way to reduce performance degradation caused by ICI in OFDM systems is to widen the subcarrier spacing. However, widening the subcarrier spacing shortens the length of OFDM symbols. Consequently, there is a problem where the overhead required to support the same cell coverage (or the overhead of the cyclic prefix required to support the same channel delay spread) increases. Therefore, a method is needed to compensate for ICI caused by phase noise without widening the subcarrier spacing.

[0149] Phase noise causes signal distortion in the time domain by arbitrarily shifting the phase of the signal. However, since OFDM signals transmit data in parallel by dividing it among multiple subcarriers, the reference signal is also placed on a specific subcarrier in the frequency domain. Consequently, channel estimation and compensation are also performed in the frequency domain, making it difficult to estimate and compensate for the effects of phase noise that changes in the time domain. Embodiments for solving this problem will be described below with reference to FIGS. 11 to 13.

[0150] This specification proposes a structure for a reference signal capable of compensating for inter-carrier interference (ICI) caused by random phase noise by superimposing and transmitting a PT-RS with DFT-precoding applied to the data, thereby estimating and compensating for phase noise in the time domain at the receiver. This will be explained below with reference to FIGS. 11 and 12.

[0151] FIG. 11 illustrates a PT-RS transmission structure according to an embodiment of the present specification. FIG. 12 illustrates a PT-RS group according to an embodiment of the present specification.

[0152] Referring to FIG. 11, the Resource Allocation block places PT-RS in Time-domain 1. Time-domain 1 is a sub-sampled region of Time-domain 2 where the actual OFDM signal is transmitted. Specifically, Time-domain 1 is associated with the (PT-RS) sample, and Time-domain 2 is associated with the (OFDM) symbol.

[0153] FIG. 12 illustrates a PT-RS placed in Time-domain 1 (sample area). In FIG. 12, a set of PT-RS (PT-RS samples) placed in adjacent Resource Elements is called a PT-RS group. The size of the PT-RS group and the spacing between PT-RS groups can be set / instructed based on upper-layer parameters. The size of the PT-RS group and the spacing between PT-RS groups may vary depending on the state of the transmission channel.

[0154] Referring to Fig. 11, as described above, the PT-RS placed in time domain 1 is precoded through DFT and added with data in the frequency domain.

[0155] Transmission signal in the frequency domain It can be expressed as shown in the following mathematical formula 5.

[0156]

[0157] In mathematical formula 5, is a data signal, and is a phase-tracing reference signal with DFT precoding applied, and is the Boosting factor of the phase tracking reference signal.

[0158] Performing DFT precoding has the effect of distributing PT-RS across the entire resource area where data is placed. The PT-RS with DFT precoding applied is multiplied by a boosting factor α before being added to the data. As the value of α increases, the power of the PT-RS increases, which improves the accuracy of the estimated phase noise, but increases the interference that the PT-RS exerts on the data. Data superimposed with the PT-RS in this way is then distributed in the frequency domain in the same way as a standard OFDM system, followed by OFDM modulation and cyclic prefix insertion, and then transmitted.

[0159] FIG. 13 illustrates a phase noise compensation receiver according to an embodiment of the present specification.

[0160] Referring to Fig. 13, the signal r[n] received through the channel can be expressed as in the following mathematical equation 6.

[0161]

[0162] In mathematical formula 6, represents the convolution operation, and x[n] is the transmitted signal, and is phase noise, h[n] is channel impulse response, and w[n] is additive white noise.

[0163] The signal after OFDM demodulation (FFT) and perfect channel equalization can be expressed as shown in the following mathematical equation 7.

[0164]

[0165] In mathematical formula 7, represents an N-point circular convolution operation, and is with N-point FFT applied and X[k] is x[n] with N-point FFT applied, and w[n] with N-point FFT applied, where N is the FFT size.

[0166] After channel equalization, the signal is converted into the time domain (e.g., time domain 1) by extracting resources of the area to be received and using the Inverse Discrete Fourier Transform (IDFT), as shown in the following mathematical equation 8.

[0167]

[0168] In mathematical formula 8, is D[k] with IDFT applied, and is PT-RS, and is a PT-RS boosting factor, and is phase noise, and is additive white noise. m is the index in time domain 1.

[0169] Referring to Fig. 13, the phase noise in PT-RS estimated through angle estimation on PT-RS is given by the following Equation 9.

[0170]

[0171] Figure 14 illustrates phase noise and estimated phase noise.

[0172] In Fig. 14, it is assumed that data is assigned to 10 resource blocks, and PT-RS is assigned to 4 resource elements per resource block. Fig. 14(a) shows the original phase noise applied to the channel, and Fig. 14(b) shows the phase noise estimated based on PT-RS. In this example, the Boosting factor α is 1 (0 dB), the SNR is 20 dB, and no multipath channel is applied. As can be seen from the results in Fig. 14, the phase noise can be estimated based on PT-RS with DFT precoding applied.

[0173] Referring to Fig. 13, the phase noise in the entire data can be obtained as follows using the phase noise estimated based on PT-RS. After averaging the values ​​estimated in each PT-RS group, the phase noise in the entire data can be estimated through linear interpolation of the phase noise estimated between the PT-RS groups. After compensating the estimated phase noise (multiplying by the complex conjugate of the estimated phase noise), the original data in the frequency domain can be obtained through DFT.

[0174] Since the PT-RS overlaps with the data, it acts as interference during data decoding, degrading data decoding performance. To reduce the amount of interference caused by the PT-RS, the PT-RS can be removed at the receiver. The PT-RS canceller in Fig. 13 removes interference caused by the PT-RS by reconstructing the PT-RS that has passed through the channel using the estimated channel and then subtracting the reconstructed PT-RS from the received signal. This improves data decoding performance. When reconstructing the PT-RS, the PT-RS boosting factor α can be used in addition to the channel information H[k]. The value of α can be set / instructed to the receiver through separate signaling (e.g., DCI / MAC-CE / RRC).

[0175] The effects according to the embodiments of this specification are as follows. In an OFDM system, by using a phase tracking signal to which DFT-precoding has been applied to estimate and compensate for phase noise in the time domain, inter-carrier interference caused by random phase noise as well as common phase noise can be eliminated.

[0176] In terms of implementation, operations related to signal generation / phase noise estimation according to the embodiments described above can be processed by the device of FIGS. 1 to 5 described above (e.g., the processor (202a, 202b) of FIG. 2).

[0177] In addition, operations related to signal generation / phase noise estimation according to the above-described embodiment may be stored in memory (e.g., 204a, 204b of FIG. 2) in the form of instructions / programs (e.g., instructions, executable code) for driving at least one processor (e.g., processor (202a, 202b) of FIG. 2).

[0178] The embodiments described above will be explained in detail below with reference to FIG. 15 in terms of the operation of a wireless device (base station or terminal). The methods described below are distinguished only for convenience of explanation, and it is obvious that a part of one method may be substituted with a part of another method or combined with one another and applied.

[0179] FIG. 15 is a flowchart illustrating a method according to one embodiment of the present specification.

[0180] Referring to FIG. 15, a method according to one embodiment of the present specification includes an OFDM signal generation step (S1510) and an OFDM signal transmission step (S1520).

[0181] In S1510, the wireless device generates an Orthogonal Frequency Division Multiplexing (OFDM) signal. For example, the first wireless device (base station or terminal) generates an OFDM signal.

[0182] In S1520, the wireless device transmits the OFDM signal. For example, the first wireless device (base station or terminal) transmits the OFDM signal to the second wireless device (terminal or base station). For example, the OFDM signal may be associated with an uplink channel or a downlink channel. For example, the transmission of the OFDM signal may be a downlink transmission or an uplink transmission.

[0183] The above OFDM signal can be generated based on the embodiments described above. It will be explained in detail below.

[0184] According to one embodiment, the OFDM signal can be generated based on the values ​​of resource elements (REs) based on subcarrier indices. For example, the value of each resource element for generating the OFDM signal is It can be expressed as. Here, p is the antenna port, and is the subcarrier spacing configuration, l is the OFDM symbol index, and k is the subcarrier index.

[0185] The values ​​of the above REs may be based on information mapped to the above REs. The information mapped to the above REs may be generated based on the overlap of data and PTRS. This will be explained in detail below.

[0186] The information mapped to the above REs can be generated based on the sum of i) data and ii) a Phase Tracking Reference Signal (PTRS) to which precoding related to the Discrete Fourier Transform (DFT) has been applied. This embodiment may be based on Equation 5. Specifically, the information mapped to the above REs may be based on X[k] of Equation 5. More specifically, the information mapped to the above REs may be generated as follows.

[0187] The information mapped to the REs can be generated by multiplying the PTRS to which the above DFT precoding has been applied by a boosting factor and then adding the data. For example, the boosting factor can be set based on control information or upper-layer signaling.

[0188] The estimation of phase noise based on the above OFDM signal is explained in detail below.

[0189] According to one embodiment, first information may be generated based on an Inverse Discrete Fourier Transform (IDFT) associated with the OFDM signal. Based on the first information, a first phase noise associated with the PTRS may be estimated. Based on linear interpolation of the first phase noise, a second phase noise associated with the data may be estimated. Based on the DFT of the first information compensated for the second phase noise, the data may be decoded. For example, the first information may be based on s[m] of Equation 8. For example, the first phase noise may be based on Equation 9. For example, the second phase noise may be based on the phase noise of the entire data estimated through linear interpolation based on the average value of the first phase noise.

[0190] The operation based on S1510 to S1520 described above can be implemented by the device of FIG. 2. For example, a wireless device (200a or 200b) can control one or more transceivers (206a or 206b) and / or one or more memories (204a or 204b) to perform the operation based on S1510 to S1520.

[0191] Although the embodiments described above have been described with a focus on the transmission operation of the first wireless device (base station or terminal), it is evident that such embodiments can be applied to the reception operation of the second wireless device (terminal or base station). Specifically, the embodiments applied to the OFDM signal generation step and the OFDM transmission step described above can be applied to the OFDM signal reception step.

[0192] Here, the wireless communication technology implemented in the wireless devices (200a, 200b) of this specification may include LTE, NR, and 6G, as well as Narrowband Internet of Things for low-power communication. For example, NB-IoT technology may be an example of LPWAN (Low Power Wide Area Network) technology and may be implemented according to standards such as LTE Cat NB1 and / or LTE Cat NB2, but is not limited to the names mentioned above. Additionally, or generally, the wireless communication technology implemented in the wireless devices (200a, 200b) of this specification may perform communication based on LTE-M technology. For example, LTE-M technology may be an example of LPWAN technology and may be referred to by various names such as eMTC (enhanced Machine Type Communication). For example, LTE-M technology may be implemented in at least one of various standards such as 1) LTE CAT 0, 2) LTE Cat M1, 3) LTE Cat M2, 4) LTE non-BL (non-Bandwidth Limited), 5) LTE-MTC, 6) LTE Machine Type Communication, and / or 7) LTE M, and is not limited to the names mentioned above. Additionally or generally, wireless communication technology implemented in the wireless devices (200a, 200b) of this specification may include at least one of ZigBee, Bluetooth, and Low Power Wide Area Network (LPWAN) for low-power communication, and is not limited to the names mentioned above. As an example, ZigBee technology can create personal area networks (PANs) related to small / low-power digital communication based on various standards such as IEEE 802.15.4, and may be referred to by various names.

[0193] The embodiments described above are combinations of the components and features of this specification in a specific form. Each component or feature should be considered optional unless otherwise explicitly stated. Each component or feature may be implemented in a form not combined with other components or features. Additionally, it is possible to construct embodiments of this specification by combining some components and / or features. The order of operations described in the embodiments of this specification may be changed. Some components or features of one embodiment may be included in another embodiment, or may be replaced with corresponding components or features of another embodiment. It is obvious that embodiments may be constructed by combining claims that do not have an explicit citation relationship in the claims, or that they may be included as new claims through amendments made after filing.

[0194] Embodiments according to the present specification may be implemented by various means, e.g., hardware, firmware, software, or a combination thereof. In the case of implementation by hardware, an embodiment of the present invention may be implemented by one or more ASICs (application specific integrated circuits), DSPs (digital signal processors), DSPDs (digital signal processing devices), PLDs (programmable logic devices), FPGAs (field programmable gate arrays), processors, controllers, microcontrollers, microprocessors, etc.

[0195] In the case of implementation by firmware or software, an embodiment of the present specification may be implemented in the form of a module, procedure, function, etc., that performs the functions or operations described above. The software code may be stored in memory and executed by a processor. The memory may be located inside or outside the processor and may exchange data with the processor by various known means.

[0196] It is obvious to those skilled in the art that this specification may be embodied in other specific forms without departing from the essential features of this specification. Accordingly, the detailed description set forth above should not be interpreted restrictively in all respects but should be considered illustrative. The scope of this specification shall be determined by a reasonable interpretation of the appended claims, and all modifications within the equivalent scope of this specification are included within the scope of this specification.

Claims

1. Regarding the method, A step of generating an Orthogonal Frequency Division Multiplexing (OFDM) signal; and The step of transmitting the above OFDM signal; comprising, The above OFDM signal is generated based on the values ​​of resource elements (RE) based on subcarrier indices, and The values ​​of the above REs are based on information mapped to the above REs, and A method characterized by the information mapped to the above REs being generated based on the sum of i) data and ii) a Phase Tracking Reference Signal (PTRS) to which precoding related to the Discrete Fourier Transform (DFT) has been applied.

2. In Paragraph 1, First information is generated based on the Inverse Discrete Fourier Transform (IDFT) associated with the above OFDM signal, and Based on the above first information, a first phase noise associated with the PTRS is estimated, and A method characterized by estimating a second phase noise associated with the data based on linear interpolation of the first phase noise.

3. In Paragraph 2, A method characterized by decoding the data based on the DFT of the first information in which the second phase noise is compensated.

4. In Paragraph 1, A method characterized in that the above OFDM signal is associated with an uplink channel or a downlink channel.

5. In Paragraph 1, A method characterized in that the transmission of the above ODFM signal is a downlink transmission or an uplink transmission.

6. In Paragraph 1, A method characterized by generating information mapped to the REs by multiplying the PTRS to which the above DFT precoding has been applied by a boosting factor and then adding the above data.

7. In Paragraph 6, A method characterized in that the above boosting factor is set based on control information or upper-level signaling.

8. In a wireless device, One or more transmitters / receivers; One or more processors controlling the above one or more transceivers; and It includes one or more memories connected to the above one or more processors and storing instructions, A wireless device characterized by the above instructions, based on execution by the one or more processors, enabling the wireless device to perform all steps of the method according to any one of claims 1 to 7.

9. In Paragraph 8, A wireless device characterized in that the above wireless device is a base station or a terminal.

10. An apparatus comprising one or more memories and one or more processors functionally connected to the one or more memories, An apparatus characterized in that the above one or more memories store instructions that cause the apparatus to perform all steps of the method according to any one of claims 1 to 7, based on execution by the above one or more processors.

11. In one or more non-transitory computer-readable storage media storing instructions, One or more non-transitory computer-readable storage media characterized by instructions executable by one or more processors that cause a wireless device to perform all steps of the method according to any one of claims 1 to 7.

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