Electronic device and method for estimating doppler spread in wireless communication system

Abstract

In embodiments, an electronic device is provided. The electronic device may comprise: at least one processor; and a memory for storing instructions. The instructions, when executed by the at least one processor, may cause the electronic device to: acquire first uplink reference signals in a first symbol; acquire a first channel estimation result for the first symbol by using the first uplink reference signals; acquire second uplink reference signals in a second symbol after the first symbol; determine a first communication quality index using the first uplink reference signals, and the first channel estimation result for the first symbol; determine a second communication quality index using the second uplink reference signals, and the first channel estimation result for the first symbol; and determine Doppler spread information corresponding to the difference between the first communication quality index and the second communication quality index.

Description

Electronic device and method for estimating Doppler spread in wireless communication systems

[0001] The present disclosure relates to a wireless communication system, and more particularly, to an electronic device and method for estimating Doppler spread in a wireless communication system.

[0002] In wireless communication systems, terminals transmitting or receiving wireless signals can move. This movement of the terminals causes changes in the wireless channel. Communication equipment providing the network can estimate channel changes caused by frequency dispersion, spread, and fluctuations due to the terminal's movement.

[0003] The above information may be provided as background art to aid in understanding the present disclosure. No claim or determination is made as to whether any of the above is applicable as prior art related to the present disclosure.

[0004] In embodiments, an electronic device is provided. The electronic device may include at least one processor and a memory storing instructions. The instructions, when executed by the at least one processor, may cause the electronic device to obtain first uplink reference signals in a first symbol, obtain a first channel estimation result for the first symbol using the first uplink reference signals, obtain second uplink reference signals in a second symbol subsequent to the first symbol, determine a first communication quality index using the first uplink reference signals and the first channel estimation result for the first symbol, determine a second communication quality index using the second uplink reference signals and the first channel estimation result for the first symbol, and determine Doppler spread information corresponding to a difference between the first communication quality index and the second communication quality index.

[0005] In embodiments, a method performed by an electronic device is provided. The method may include: obtaining first uplink reference signals in a first symbol; obtaining a first channel estimation result for the first symbol using the first uplink reference signals; obtaining second uplink reference signals in a second symbol subsequent to the first symbol; determining a first communication quality index using the first uplink reference signals and the first channel estimation result for the first symbol; determining a second communication quality index using the second uplink reference signals and the first channel estimation result for the first symbol; and determining Doppler spread information corresponding to a difference between the first communication quality index and the second communication quality index.

[0006] In embodiments, an electronic device is provided. The electronic device may include at least one processor and a memory storing instructions. The instructions, when executed by the at least one processor, may cause the electronic device to obtain first uplink reference signals in a first symbol, obtain second uplink reference signals in a second symbol subsequent to the first symbol, obtain a channel estimation result for the second symbol using the second uplink reference signals, determine a first communication quality index using the first uplink reference signals and the channel estimation result, determine a second communication quality index using the second uplink reference signals and the channel estimation result, and determine Doppler spread information corresponding to a difference between the first communication quality index and the second communication quality index.

[0007] In embodiments, an electronic device is provided. The electronic device may include at least one processor and at least one transceiver. The at least one processor may be configured to obtain first downlink reference signals in a first symbol via the at least one transceiver. The at least one processor may be configured to obtain a first channel estimation result for the first symbol using the first downlink reference signals. The at least one processor may be configured to obtain second downlink reference signals in a second symbol subsequent to the first symbol via the at least one transceiver. The at least one processor may be configured to determine a first communication quality index using the first downlink reference signals and the first channel estimation result for the first symbol. The at least one processor may be configured to determine a second communication quality index using the second downlink reference signals and the first channel estimation result for the first symbol. The at least one processor may be configured to determine Doppler spread information corresponding to a difference between the first communication quality indicator and the second communication quality indicator.

[0008] In embodiments, an electronic device is provided. The electronic device may include at least one processor and at least one transceiver. The at least one processor may be configured to obtain, via the at least one transceiver, first uplink reference signals in a first symbol. The at least one processor may be configured to obtain, via the at least one transceiver, second uplink reference signals in a second symbol subsequent to the first symbol. The at least one processor may be configured to obtain a channel estimation result for the second symbol using the second uplink reference signals. The at least one processor may be configured to determine a first communication quality index using the first uplink reference signals and the channel estimation result. The at least one processor may be configured to determine a second communication quality index using the second uplink reference signals and the channel estimation result. The at least one processor may be configured to determine Doppler spread information corresponding to a difference between the first communication quality index and the second communication quality index.

[0009] In embodiments, an electronic device is provided. The electronic device may include at least one processor and a memory storing instructions. The instructions, when executed by the at least one processor, may cause the electronic device to obtain first downlink reference signals in a first symbol, obtain a first channel estimation result for the first symbol using the first downlink reference signals, obtain second downlink reference signals in a second symbol subsequent to the first symbol, determine a first communication quality index using the first downlink reference signals and the first channel estimation result for the first symbol, determine a second communication quality index using the second downlink reference signals and the first channel estimation result for the first symbol, and determine Doppler spread information corresponding to a difference between the first communication quality index and the second communication quality index.

[0010] In embodiments, an electronic device is provided. The electronic device may include at least one processor and a memory storing instructions. The instructions, when executed by the at least one processor, may cause the electronic device to obtain first downlink reference signals in a first symbol, obtain second downlink reference signals in a second symbol subsequent to the first symbol, obtain a channel estimation result for the second symbol using the second downlink reference signals, determine a first communication quality index using the first downlink reference signals and the channel estimation result, determine a second communication quality index using the second downlink reference signals and the channel estimation result, and determine Doppler spread information corresponding to a difference between the first communication quality index and the second communication quality index.

[0011] Figure 1 shows a wireless communication system.

[0012] Figure 2 shows network entities according to distributed deployment.

[0013] Figure 3 shows an example of a resource structure in the time domain and frequency domain.

[0014] Figure 4 shows an example of function split of network entities.

[0015] Figure 5 shows examples of channels in a communication standard.

[0016] Figures 6a and 6b show examples of reference signals (RSs) within a slot.

[0017] Figure 7 shows examples of functional blocks for processing a received signal.

[0018] Figures 8a and 8b show examples of constellations for received signals.

[0019] Figures 9a and 9b show examples of calculation of communication quality using two RSs.

[0020] Figure 10 shows the relationship between communication quality difference and Doppler frequency.

[0021] Figures 11a and 11b show examples of the performance of Doppler estimation using correlation.

[0022] Figures 12a and 12b show examples of the performance of Doppler estimation using communication quality.

[0023] Figure 13 shows the operation flow of an electronic device for determining Doppler spread information by utilizing differences in communication qualities.

[0024] Figure 14a illustrates the functional configuration of a DU (digital unit).

[0025] Figure 14b illustrates the functional configuration of a wireless communication device.

[0026] The terms used in this disclosure are used only to describe specific embodiments and may not be intended to limit the scope of other embodiments. The singular expression may include plural expressions unless the context clearly indicates otherwise. Terms used herein, including technical or scientific terms, may have the same meaning as commonly understood by those of ordinary skill in the art described in this disclosure. Terms defined in general dictionaries among the terms used in this disclosure may be interpreted as having the same or similar meaning in the context of the relevant technology, and shall not be interpreted in an idealized or overly formal sense unless explicitly defined in this disclosure. In some cases, even if a term is defined in this disclosure, it cannot be interpreted to exclude embodiments of the present disclosure.

[0027] The various embodiments of the present disclosure described below illustrate a hardware-based approach as an example. However, since the various embodiments of the present disclosure include techniques utilizing both hardware and software, the various embodiments of the present disclosure do not exclude a software-based approach.

[0028] In the following description, terms referring to signals (e.g., signal, information, message, signaling), terms referring to data types (e.g., list, set, subset), terms for operational states (e.g., step, operation, procedure), terms referring to data (e.g., packet, user stream, information, bit, symbol, codeword), terms referring to resources (e.g., symbol, slot, subframe, radio frame, subcarrier, resource element (RE), resource block (RB), bandwidth part (BWP), occasion), terms referring to channels, terms referring to network entities, terms referring to components of devices, etc. are examples for convenience of description. Therefore, the present disclosure is not limited to the terms described below, and other terms having equivalent technical meanings may be used. In addition, the terms '...bu', '...gi', '...mul', '...che', etc. used below may mean at least one shape structure or a unit that processes a function.

[0029] In addition, in the present disclosure, expressions such as "more than" or "less than" may be used to determine whether a specific condition is satisfied or fulfilled, but this is merely a description for expressing an example and does not exclude descriptions such as "more than" or "less than." A condition described as "more than" may be replaced with "more than," a condition described as "less than" may be replaced with "less than," and a condition described as "more than and less than" may be replaced with "more than and less than." In addition, hereinafter, "A" to "B" mean at least one of elements from A (including A) to B (including B). hereinafter, "C" and / or "D" mean at least one of "C" or "D," that is, including {"C", "D", "C" and "D"}.

[0030] Although the present disclosure describes various embodiments using terms used in some communication standards (e.g., 3rd Generation Partnership Project (3GPP), European Telecommunications Standards Institute (ETSI), extensible radio access network (xRAN), open-radio access network (O-RAN), etc.), these are merely examples for explanation. The various embodiments of the present disclosure can be easily modified and applied to other communication systems.

[0031] In the present disclosure, the communication quality may be, for example, at least one of RSRP (reference signal received power), BRSRP (beam reference signal received power), RSRQ (reference signal received quality), RSSI (received signal strength indicator), SINR (signal to interference and noise ratio), CINR (carrier to interference and noise ratio), SNR (signal to noise ratio), EVM (error vector magnitude), BER (bit error rate), and BLER (block error rate). In addition to the examples described above, other terms having equivalent technical meanings or other metrics indicating channel quality may be used. Hereinafter, in the present disclosure, high communication quality means a case where a communication quality value related to a signal size is large or a communication quality value related to an error rate is small. A higher communication quality may mean that a smooth wireless communication environment is guaranteed. In addition, an optimal beam may mean a beam having the highest communication quality among beams.

[0032] Figure 1 shows a wireless communication system.

[0033] Referring to FIG. 1, FIG. 1 illustrates a base station (110) and a terminal (120) as some of the nodes utilizing a wireless channel in a wireless communication system. Although FIG. 1 illustrates only one base station, the wireless communication system may further include other base stations identical or similar to the base station (110).

[0034] The base station (110) is a network infrastructure that provides wireless access to terminals (120). The base station (110) has coverage defined based on the distance at which a signal can be transmitted. In addition to the base station, the base station (110) includes an 'access point (AP)', a 'RAN (radio access network) node', an 'eNodeB (eNB)', and a '5G node (5 th The term "network node" may be referred to as "next generation node (gNB)", "wireless point", "transmission / reception point (TRP)", "communication node", "wireless communication device", "wireless communication equipment", "network node", "network entity", or other terms having equivalent technical meaning.

[0035] The terminal (120) is a device used by a user and communicates with the base station (110) via a wireless channel. The link from the base station (110) to the terminal (120) is referred to as a downlink (DL), and the link from the terminal (120) to the base station (110) is referred to as an uplink (UL). In addition, although not shown in FIG. 1, the terminal (120) and another terminal may communicate with each other via a wireless channel. In this case, the link between the terminal (120) and another terminal (device-to-device link, D2D) is referred to as a sidelink, and the sidelink may be used interchangeably with the PC5 interface. In some other embodiments, the terminal (120) may be operated without the involvement of a user. In one embodiment, the terminal (120) is a device that performs machine type communication (MTC) and may not be carried by the user. Additionally, according to one embodiment, the terminal (120) may be an NB (narrowband)-IoT (internet of things) device.

[0036] The terminal (120) may be referred to as a terminal, or other terms such as 'user equipment (UE),' 'customer premises equipment (CPE),' 'mobile station,' 'subscriber station,' 'remote terminal,' 'wireless terminal,' 'electronic device,' or 'user device,' or other terms having equivalent technical meanings.

[0037] The base station (110) can perform beamforming with the terminal (120). The base station (110) and the terminal (120) can transmit and receive wireless signals in a relatively low frequency band (e.g., FR 1 (frequency range 1) of NR). In addition, the base station (110) and the terminal (120) can transmit and receive wireless signals in a relatively high frequency band (e.g., FR 2 (or, FR 2-1, FR 2-2, FR 2-3), FR 3 of NR), millimeter wave (mmWave) band (e.g., 26 GHz, 28 GHz, 30 GHz, 38 GHz, 60 GHz)). To improve channel gain, the base station (110) and the terminal (120) can perform beamforming. Here, the beamforming can include transmission beamforming and reception beamforming. The base station (110) and the terminal (120) can impart directionality to the transmitted or received signal. To this end, the base station (110) and the terminal (120) can select serving beams through a beam search or beam management procedure. After the serving beams are selected, subsequent communication can be performed through resources that have a QCL relationship with the resource that transmitted the serving beams.

[0038] If large-scale characteristics of a channel carrying a symbol on a first antenna port can be inferred from a channel carrying a symbol on a second antenna port, the first antenna port and the second antenna port can be evaluated to have a QCL relationship. For example, the large-scale characteristics may include at least one of delay spread, Doppler spread, Doppler shift, average gain, average delay, and a spatial receiver parameter.

[0039] Although both the base station (110) and the terminal (120) are described as performing beamforming in FIG. 1, the embodiments of the present disclosure are not necessarily limited thereto. In some embodiments, the terminal may or may not perform beamforming. Furthermore, the base station may or may not perform beamforming. That is, either only one of the base station and the terminal may perform beamforming, or neither the base station nor the terminal may perform beamforming.

[0040] In the present disclosure, a beam refers to a spatial flow of a signal in a wireless channel, and is formed by one or more antennas (or antenna elements), and this forming process may be referred to as beamforming. Beamforming may include at least one of analog beamforming and digital beamforming (e.g., precoding). Reference signals transmitted based on beamforming may include, for example, a demodulation-reference signal (DMRS), a channel state information-reference signal (CSI-RS), a synchronization signal / physical broadcast channel (SS / PBCH), and a sounding reference signal (SRS). In addition, as a configuration for each reference signal, an IE such as a CSI-RS resource or an SRS-resource may be used, and this configuration may include information associated with the beam. Information associated with a beam may mean whether the configuration (e.g., a CSI-RS resource) uses the same spatial domain filter as another configuration (e.g., another CSI-RS resource within the same CSI-RS resource set) or a different spatial domain filter, or whether it is quasi-co-located (QCL) with a reference signal, and if so, what type it is (e.g., QCL type A, B, C, D).

[0041] FIG. 2 illustrates network entities according to a distributed arrangement. For example, the network entities may include a digital unit (DU) and a radio unit (RU) (220) (or a massive multiple input multiple output (MMU) unit). For example, the network entities may be connected via a fronthaul. Unlike the backhaul between a base station and a core network, the fronthaul refers to entities (e.g., DU (210), RU (220)) between a wireless LAN and a base station. Although FIG. 2 illustrates an example of a fronthaul structure between a DU (210) and one RU (220), this is merely for convenience of explanation and the present disclosure is not limited thereto. In other words, embodiments of the present disclosure may also be applied to a fronthaul structure between one DU and multiple RUs. For example, embodiments of the present disclosure may be applied to a fronthaul structure between one DU and two RUs. Additionally, the embodiments of the present disclosure can also be applied to a fronthaul structure between one DU and three RUs.

[0042] Referring to FIG. 2, the base station (110) may include a DU (210) and a RU (220). The front hole (215) between the DU (210) and the RU (220) is F xIt can be operated through an interface. For the operation of the fronthaul (215), for example, an interface such as eCPRI (enhanced common public radio interface) and ROE (radio over ethernet) can be used. Depending on the implementation example, in addition to the DU (digital unit), the DU (210) may be referred to as a baseband unit (BBU), a digital BBU, a baseband digital unit, a digital processing unit, a digital processing circuit, a baseband processing circuit, a baseband processing unit, and / or equivalent technical terms thereof. Depending on the implementation example, in addition to the RU (radio unit), the RU (220) may be referred to as a remote unit, a radio demote head (RRH), a radio processing circuit, a radio processing unit, an antenna integrated radio, an air radio device, an air scale communication device, a radio device, a radio communication device, and / or equivalent technical terms thereof. Also, according to the implementation example, the network entity connected to the DU (210) in the present disclosure is described as the RU (210), but it is of course possible for a massive multiple input multiple output (MMU) unit to be connected to the DU (210) and used instead of the RU (210).

[0043] As communication technology advances, mobile data traffic increases, significantly increasing the bandwidth requirements for the fronthaul between the digital unit and the wireless unit. In a deployment such as a centralized / cloud radio access network (C-RAN), the DU performs functions for the packet data convergence protocol (PDCP), radio link control (RLC), media access control (MAC), and physical (PHY) layer, while the RU can be implemented to perform functions for the PHY layer in addition to the radio frequency (RF) function. The DU (210) can be responsible for upper layer functions of the wireless network.

[0044] For example, DU (210) can perform functions of MAC layer and part of PHY layer. Here, part of PHY layer means functions performed at a higher level among the functions of PHY layer, and may include, for example, channel encoding (or channel decoding), scrambling (or descrambling), modulation (or demodulation), layer mapping (or layer demapping). According to an embodiment, if DU (210) complies with O-RAN standard, it may be referred to as O-DU (O-RAN DU). DU (210) may be replaced and expressed as a first network entity for a base station (e.g., gNB) in embodiments of the present disclosure, if necessary. RU (220) may be in charge of lower layer functions of a wireless network. For example, RU (220) may perform part of PHY layer and RF functions. Here, a part of the PHY layer refers to functions of the PHY layer that are performed at a relatively lower level than the DU (210), and may include, for example, iFFT transform (or FFT transform), CP insertion (CP removal), and digital beamforming. The RU (220) may be referred to as an 'access unit (AU)', an 'access point (AP)', a 'transmission / reception point (TRP)', a 'remote radio head (RRH)', a 'radio unit (RU)', or other terms having an equivalent technical meaning thereto. According to an embodiment, when the RU (220) complies with the O-RAN standard, it may be referred to as an O-RU (O-RAN RU). The RU (220) may be expressed by being replaced with a second network entity for a base station (e.g., gNB) in embodiments of the present disclosure, as needed.

[0045] In FIG. 2, the base station (110) is described as including a DU (210) and a RU (220), but the embodiments of the present disclosure are not limited thereto. The base station according to the embodiments may be implemented in a distributed deployment according to a centralized unit (CU) configured to perform functions of upper layers of an access network (e.g., packet data convergence protocol (PDCP), radio resource control (RRC)) and a distributed unit (DU) configured to perform functions of lower layers. For example, the digital unit (DU) (210) may be implemented by being separated into the CU and the DU. Between a core (e.g., 5GC (5G core) or NGC (next generation core)) network and a radio network (RAN), the base station may be implemented in a structure in which the CU, DU, and RU are arranged in that order. The interface between the CU and the distributed unit (DU) may be referred to as an F1 interface.

[0046] A centralized unit (CU) can be connected to one or more DUs and can be responsible for functions at a higher layer than the DU. For example, the CU can be responsible for functions at the RRC (radio resource control) and PDCP (packet data convergence protocol) layers, while the DU and RU can be responsible for functions at lower layers. The DU can perform some functions (high PHY) of the RLC (radio link control), MAC (media access control), and PHY (physical) layers, while the RU can be responsible for the remaining functions (low PHY) of the PHY layer. In addition, for example, a digital unit (DU) can be included in a distributed unit (DU) depending on the implementation of a distributed deployment of the base station. Hereinafter, unless otherwise defined, the operations of DU (digital unit) and RU are described, but various embodiments of the present disclosure can be applied to both a base station arrangement including a CU and an arrangement in which a DU is directly connected to a core network (i.e., a base station in which the CU and DU are integrated into a single entity (e.g., an NG-RAN node)).

[0047] Figure 3 illustrates examples of resource structures in the time and frequency domains. Figure 3 illustrates the basic structure of the time-frequency domain, a radio resource domain where data or control channels are transmitted in the downlink or uplink.

[0048] Referring to Figure 3, the horizontal axis represents the time domain and the vertical axis represents the frequency domain. The minimum transmission unit in the time domain is an OFDM symbol, N symbOFDM symbols (302) are grouped to form one slot (306). The length of a subframe is defined as 1.0 ms, and the length of a radio frame (314) is defined as 10 ms. The minimum transmission unit in the frequency domain is a subcarrier, and the carrier bandwidth constituting the resource grid is N BW It consists of a number of subcarriers (304).

[0049] The basic unit of resources in the time-frequency domain is a resource element (RE) (312), which can be represented by an OFDM symbol index and a subcarrier index. A resource block may include multiple resource elements. In the LTE system, a resource block (RB) (or physical resource block (PRB)) is N in the time domain. symb N consecutive OFDM symbols and frequency domain SC RB are defined as N consecutive subcarriers. In the NR system, a resource block (RB) (308) is defined as N in the frequency domain. SC RB can be defined as a series of consecutive subcarriers (310). One RB (308) is N in the frequency axis. SC RB It contains REs (312). In general, the minimum transmission unit of data is RB and the number of subcarriers is N. SC RB=12. The frequency domain may include common resource blocks (CRBs). Physical resource blocks (PRBs) may be defined in the bandwidth part (BWP) of the frequency domain. The CRB and PRB numbers may be determined based on the subcarrier spacing. The data rate may increase in proportion to the number of RBs scheduled to the terminal.

[0050] In the NR system, in the case of a frequency division duplex (FDD) system that operates the downlink and uplink by frequency division, the downlink transmission bandwidth and the uplink transmission bandwidth may be different. The channel bandwidth represents the radio frequency (RF) bandwidth corresponding to the system transmission bandwidth. [Table 1] shows part of the correspondence between the system transmission bandwidth, subcarrier spacing (SCS), and channel bandwidth defined in the NR system in a frequency band lower than x GHz (e.g., frequency range (FR) 1 (310 MHz to 7125 MHz)). And [Table 2] shows part of the correspondence between the transmission bandwidth, subcarrier spacing, and channel bandwidth defined in the NR system in a frequency band higher than y GHz (e.g., FR 2 (24250 MHz - 52600 MHz) or FR 2-2 (52600 MHz to 71000 MHz)). For example, an NR system with a 100 MHz channel bandwidth and 30 kHz subcarrier spacing has a transmission bandwidth of 273 RBs. In [Table 1] and [Table 2], N / A may indicate a bandwidth-subcarrier combination not supported by the NR system.

[0051] Channel bandwidth [MHz] SCS 5 10 20 50 80 100 Transmission bandwidth configuration N RB15kHz2552106207N / AN / A30kHz11245113321727360kHzN / A112465107135

[0052] Channel bandwidth [MHz] SCS50100200400 Transmission bandwidth configuration N RB 60kHz66132264N / A120kHz3266132264

[0053] Figure 4 shows an example of function splitting of network entities. As wireless communication technology advances (e.g., 5G (5 th With the introduction of 5G communication systems (or NR (new radio) communication systems), the frequency bands used have increased further. As the cell radius of base stations has become significantly smaller, the number of RUs required for installation has also increased further. Furthermore, in 5G communication systems, the amount of data transmitted has increased by a factor of up to ten, significantly increasing the transmission capacity of wired networks transmitted to the fronthaul. Due to the factors described above, the installation cost of wired networks in 5G communication systems may increase significantly. Therefore, in order to lower the transmission capacity of wired networks and reduce the installation cost of wired networks, 'function split' can be utilized to transfer some of the functions of the modem of the DU to the RU, thereby lowering the transmission capacity of the fronthaul. Although described as RU below, the function split described below can be equally applied not only to RUs but also to the relationship between the MMU and the DU.

[0054] To reduce the burden on the DU, the role of the RU, which is traditionally solely responsible for RF functions, can be expanded to include some physical layer functions. As the RU performs higher-layer functions, its throughput increases, which can increase transmission bandwidth in the fronthaul while reducing latency requirements due to response processing. However, as the RU performs higher-layer functions, virtualization gains decrease, and the RU's size, weight, and cost increase. Considering the trade-offs between the advantages and disadvantages described above, implementing an optimal functional separation is required.

[0055] Referring to Figure 4, the functional separation in the physical layer below the MAC layer is illustrated. For the downlink (DL) that transmits a signal to a terminal through a wireless network, the base station can sequentially perform channel encoding / scrambling, modulation, layer mapping, antenna mapping, RE mapping, digital beamforming (e.g., precoding), iFFT transform / CP insertion, and RF transform. For the uplink (UL) that receives a signal from a terminal through a wireless network, the base station can sequentially perform RF transform, FFT transform / CP removal, digital beamforming (pre-combining), RE demapping, channel estimation, layer demapping, demodulation, and decoding / descrambling. The separation of uplink and downlink functions can be defined in various types depending on the needs of vendors, discussions in standards, etc., according to the above-mentioned trade-offs.

[0056] In the first functional separation (405), the RU performs the RF function, and the DU performs the PHY function. The first functional separation is one in which the PHY function is not substantially implemented in the RU, and may be referred to as Option 8, for example. In the second functional separation (410), the RU performs iFFT conversion / CP insertion in the DL and FFT conversion / CP removal in the UL of the PHY function, and the DU performs the remaining PHY functions. As an example, the second functional separation (410) may be referred to as Option 7-1. In the third functional separation (420a), the RU performs iFFT conversion / CP insertion in the DL and FFT conversion / CP removal and digital beamforming in the UL of the PHY function, and the DU performs the remaining PHY functions. As an example, the third functional separation (420a) may be referred to as Option 7-2x Category A. In the fourth functional separation (420b), the RU performs up to digital beamforming in both the DL and UL, and the DU performs upper PHY functions after the digital beamforming. For example, the fourth functional separation (420b) may be referred to as Option 7-2x Category B. In the fifth functional separation (425), the RU performs up to RE mapping (or RE demapping) in both the DL and UL, and the DU performs upper PHY functions after RE mapping (or RE demapping). For example, the fifth functional separation (425) may be referred to as Option 7-2. In the sixth functional separation (430), the RU performs up to modulation (or demodulation) in both the DL and UL, and the DU performs upper PHY functions after modulation (or demodulation). For example, the sixth functional separation (430) may be referred to as Option 7-3. In the seventh functional separation (440), the RU performs encoding / scrambling (or decoding / descrambling) in both the DL and UL, and the DU performs subsequent upper PHY functions up to modulation (or demodulation). For example, the seventh functional separation (440) may be referred to as Option 6.

[0057] In one embodiment, when a large amount of signal processing is expected, such as in the FR 1 MMU, functional separation at a relatively high layer (e.g., the fourth functional separation (420b)) may be required to reduce fronthaul capacity. In addition, functional separation at too high a layer (e.g., the sixth functional separation (430)) may complicate the control interface and cause a burden on the implementation of the RU due to the inclusion of a large number of PHY processing blocks within the RU. Therefore, appropriate functional separation may be required depending on the arrangement and implementation method of the DU and the RU.

[0058] In one embodiment, if the precoding of data received from the DU cannot be processed (i.e., if the precoding capability of the RU is limited), the third functional separation (420a) or a lower functional separation (e.g., the second functional separation (410)) may be applied. Conversely, if the DU has the capability to process the precoding of data received from the DU, the fourth functional separation (420b) or a higher functional separation (e.g., the sixth functional separation (430)) may be applied.

[0059] The O-RAN standard distinguishes the types of O-RUs depending on whether the precoding function is located at the interface of the O-DU or the O-RU interface. For example, the RU may perform operations according to the functional separation of the third functional separation (420a) (which may be referred to as category A (CAT-A)) or the fourth functional separation (420b) (which may be referred to as category B (CAT-B)) for performing beamforming processing. In other words, an O-RU that does not perform precoding (i.e., has low complexity) may be referred to as a CAT-A O-RU. An O-RU that performs precoding may be referred to as a CAT-B O-RU. In addition, for example, channel estimation may be performed in the O-RU instead of the O-DU. To improve uplink performance, the O-RU may also operate according to the sixth functional separation (430) (Option 7-3).

[0060] Hereinafter, the upper-PHY refers to the physical layer processing handled in the DU of the fronthaul interface. For example, the upper-PHY may include FEC encoding / decoding, scrambling, and modulation / demodulation. The lower-PHY refers to the physical layer processing handled in the RU of the fronthaul interface. For example, the lower-PHY may include FFT / iFFT, digital beamforming, PRACH (physical random access channel) extraction and filtering. However, the above-described criteria do not exclude embodiments through other functional separations. The functional configuration, signaling, or operation of FIGS. 5 to 14b described below may be applied not only to the third functional separation (420a), the fourth functional separation (420b), but also to other functional separations (e.g., the sixth functional separation (430).

[0061] In Fig. 4, the cues between the DU and the RU are also shown. For example, channel estimation can be performed in the O-RU instead of the O-DU. To improve uplink performance, the O-RU may also operate according to the sixth functional separation (430) (Option 7-3).

[0062] Figure 5 shows examples of channels in a communication standard.

[0063] Referring to FIG. 5, the channels may include a physical channel (510), a transport channel (520), and a logical channel (530) according to layers defined in a communication standard. The physical channel (510) may provide functions (e.g., channel coding, HARQ processing, modulation, multi-antenna processing, resource mapping) necessary for generating physical signals in the physical layer. In the physical layer, the physical signals are modulated using OFDM and may be transmitted in a wireless environment through time-frequency resources (e.g., resources of the resource grid of FIG. 3).

[0064] In downlink transmission, a physical channel (510) may include at least one of a physical broadcast channel (PBCH), a physical downlink shared channel (PDSCH), or a physical downlink control channel (PDCCH). The PDCCH may be used to carry downlink control information (DCI). Generally, downlink data may refer to symbols transmitted through the PDSCH, and a downlink control signal may refer to symbols transmitted through the PDCCH. In addition, in the downlink, in addition to the channels illustrated in FIG. 4, a synchronization signal (e.g., a primary synchronization signal (PSS), a secondary synchronization signal (SSS)) and an SS / PBCH block including a broadcast signal (e.g., a PBCH)) may be transmitted for synchronization. In addition, in the downlink, a channel state information-reference signal (CSI-RS) for obtaining measurement or channel information, a demodulation reference signal (DMRS) for channel estimation and demodulation, and a phase tracking reference signal (PTRS) may be transmitted in the downlink.

[0065] In uplink transmission, a physical channel (510) may include at least one of a physical uplink shared channel (PUSCH), a physical uplink control channel (PUCCH), or a physical random access channel (PRACH). The PUSCH or PUCCH may be used to carry uplink control information (UCI). Generally, uplink data refers to symbols transmitted through the PUSCH, and the uplink control signal may mean symbols corresponding to the UCI. For example, the UCI may include at least one of a scheduling request (SR), a hybrid automatic request (HARQ)-acknowledge (ACK) bit(s), or channel state information (CSI). In addition, in the uplink, in addition to the channels illustrated in FIG. 4, DMRS and PTRS for channel estimation and demodulation may be transmitted in the downlink for channel estimation.

[0066] A transmission channel (520) connects a physical layer and a medium access channel (MAC) layer located at an upper level of the physical layer, and can be classified according to how data is transmitted via a wireless interface. In a downlink, a transmission channel (520) may include at least one of a paging channel (PCH) for paging, a broadcast channel (BCH) for broadcasting system information, or a downlink shared channel (DL-SCH) for transmitting downlink data. In an uplink, a transmission channel (520) may include at least one of a random access channel (RACH) for transmitting a random access preamble or an uplink shared channel (UL-SCH) for transmitting downlink data.

[0067] The logical channel (530) is located above the transport channel and is mapped to the transport channel (520). The logical channel (530) can be divided into a control channel for transmitting control region information and a traffic channel for transmitting user region information. The control channel of the logical channel (530) can include at least one of a paging control channel (PCCH), a broadcast control channel (BCCH), a common control channel (CCCH), or a dedicated control channel (DCCH). The traffic channel of the logical channel (530) can include a dedicated traffic channel (DTCH).

[0068] In describing embodiments of the present disclosure, "data" may refer to sequences other than reference signals. For example, "data" acquired by a receiver in uplink communication may refer to signals transmitted via a PUSCH. However, the PUSCH is merely exemplary, and it is understood that embodiments of the present disclosure may also be applied to other channels requiring channel estimation (e.g., PDSCH, PBCH, PDCCH, PUCCH).

[0069] Figures 6a and 6b illustrate examples of reference signals (RSs) within a slot. The reference signals can be used for channel estimation. For example, a demodulation reference signal (DMRS) can be used for coherent demodulation with data (e.g., PDSCH, PUSCH). Channel estimation using DMRS is exemplified below, but the embodiments of the present disclosure described below can also be applied to channel estimation using SRSs. To illustrate the channel estimation of the present disclosure and operations using DMRS for channel estimation, uplink transmission in an NR communication system is described as an example. However, the embodiments of the present disclosure are not limited to the uplink of an NR communication system. It should be understood that the embodiments of the present disclosure can also be applied to downlink or other communication systems.

[0070] Referring to FIG. 6A, a base station (e.g., base station 110, DU 210) may receive an uplink signal from a terminal (e.g., terminal 120). The terminal 120 may transmit the uplink signal to the base station 110. The received uplink signal may include data (hereinafter, “received data”) received on an uplink channel (e.g., PUSCH). The received data may be transmitted in data symbols in the time domain. In addition, the received signal may include reference signals (hereinafter, “received reference signals”) (e.g., DMRS) for channel estimation and coherent demodulation of the data symbols. The received reference signals may be transmitted in DMRS symbols in the time domain. The base station 110 may receive the received data from the terminal 120 in the data symbols of a slot and receive the received reference signals in the DMRS symbols. A slot may include 14 symbols (e.g., symbol #0 (600), symbol #1 (601), symbol #2 (602), symbol #3 (603), symbol #4 (604), symbol #5 (605), symbol #6 (606), symbol #7 (607), symbol #8 (608), symbol #9 (609), symbol #10 (610), symbol #11 (611), symbol #12 (612), and symbol #13 (613)). At least some of the 14 symbols may be used to carry DMRS sequences. For example, a section of symbol #2 (602) and a section of symbol #11 (611) may include DMRS symbols.

[0071] The base station (110) (e.g., DU (210)) can estimate the channel between the base station (110) (e.g., RU (220)) and the terminal (120) through the reception reference signals. The base station (110) can obtain information about the channel experienced by the reception reference signals. For example, the base station (110) can obtain information about the channel experienced by the reception data through the relationship between the positions where the DMRS symbols of the reception reference signals are mapped and the positions where the data symbols of the reception data are mapped. For example, the base station (110) can obtain information about the channel experienced by the reception data by performing interpolation in the frequency domain or interpolation in the time domain based on the information about the channel experienced by the reception reference signals.

[0072] The base station (110) can estimate a channel in each resource element in time-frequency resources using uplink reference signals (e.g., DMRS, SRS). Although FIG. 6A illustrates an example in which channel estimation is performed using two DMRS symbols (e.g., symbol #2 (602) and symbol #11 (611)) within one slot, the embodiments of the present disclosure are not limited thereto. The DMRS symbols used for channel estimation need not necessarily be limited to symbols within the same slot.

[0073] Referring to FIG. 6B, the base station (110) can receive uplink signals across two slots (e.g., a first slot and a second slot). The first slot can include 14 symbols (e.g., symbol #0 (600), symbol #1 (601), symbol #2 (602), symbol #3 (603), symbol #4 (604), symbol #5 (605), symbol #6 (606), symbol #7 (607), symbol #8 (608), symbol #9 (609), symbol #10 (610), symbol #11 (611), symbol #12 (612), and symbol #13 (613)). The second slot may include 14 symbols (e.g., symbol #0 (650), symbol #1 (651), symbol #2 (652), symbol #3 (653), symbol #4 (654), symbol #5 (655), symbol #6 (656), symbol #7 (657), symbol #8 (658), symbol #9 (659), symbol #10 (610), symbol #11 (611), symbol #12 (612), and symbol #13 (613)). The base station (110) may perform channel estimation through symbol #11 (6111) of the first slot and symbol #2 (652) of the second slot.

[0074] Hereinafter, reference signals used by an electronic device (e.g., a base station (110), a DU (210), or a RU (220)) that performs channel estimation for an uplink channel to perform channel estimation may be referred to as a first uplink reference signal and a second uplink reference signal. For example, a reference signal that is earlier in time may be referred to as the first uplink reference signal, and a reference signal that is later in time may be referred to as the second uplink reference signal. As an example, the first uplink reference signal may be a DMRS mapped to symbol #2 (602) of the first slot, and the second uplink reference signal may be a DMRS mapped to symbol #11 (611) of the first slot. As another example, the first uplink reference signal may be a DMRS mapped to symbol #11 (611) of the first slot, and the second uplink reference signal may be a DMRS mapped to symbol #2 (652) of the second slot.

[0075] Fig. 7 illustrates examples of functional blocks for processing a received signal. Each functional block may represent a set of logical operations or codes configured to perform a corresponding operation, or may include at least a portion of processing circuitry configured to perform a specific operation. The electronic device including the functional blocks may vary depending on the implementation example of the network node. For example, the RU (220) may be connected to the DU (210), and the network entities may be distributed according to the third functional separation (420a) or the fourth functional separation (420b). Since channel estimation is performed in the DU (210), the electronic device including the functional blocks described below may be the DU (210). The DU (210) may receive IQ values ​​for signals received in the RU (220) from the RU (220) via the fronthaul. Also, for example, RU (220) may be connected to DU (210), and network entities may be distributed according to the sixth functional separation (430). Since channel estimation is performed in RU (220), an electronic device including the functional blocks described below may be RU (220). For another example, instead of RU (220), an MMU may be connected to DU (210) to perform channel estimation. Also, for example, when all processing (e.g., reception, channel estimation, and decoding) for a received signal is performed within one node without functional separation as exemplified in FIG. 4, the electronic device including the functional blocks may be a base station (110). Hereinafter, the description will be made based on the electronic device, but operations in the functional blocks of the electronic device may be performed by the base station (110), DU (210), and / or RU (220) depending on the deployment scenario.

[0076] Referring to FIG. 7, an electronic device can obtain uplink signals transmitted from a terminal (120). The electronic device can include an FFT block (710), a channel estimation block (720), an equalization block (730), and a quality calculation block (740).

[0077] In the FFT block (710), the electronic device can perform FFT to demodulate OFDM symbols. Through the FFT, the electronic device can obtain signals mapped to each subcarrier. The signals mapped to each subcarrier can represent signals received through receiving antennas (hereinafter, “received signals”). The received signals obtained by the electronic device (e.g., the base station (110), the DU (210), or the RU (220)) can be expressed by the following mathematical equation.

[0078]

[0079]

[0080]

[0081] In the equalization block (730), the electronic device can determine a weighting matrix for equalization. For example, assuming a minimum mean square error (MMSE) receiver, the electronic device can apply MMSE weighting to the received signal. For example, the MMSE weighting can be determined according to the following mathematical equation.

[0082]

[0083]

[0084]

[0085]

[0086]

[0087] In the equalization block (730), the electronic device can obtain received signals on which equalization has been performed. For example, the operation of applying MMSE weights can be understood by the following mathematical formula.

[0088]

[0089]

[0090] In the quality calculation block (740), the electronic device can obtain a communication quality index. For example, the electronic device can calculate the communication quality index using the received signals obtained through [Mathematical Equations 1] to [Mathematical Equations 4]. To describe the communication quality index, the vector space of the received signals can be utilized. The norm value represents the distance from the origin to the actual received signal in the vector space. For example, the norm value can be determined according to the following mathematical equation.

[0091]

[0092]

[0093] The electronic device may utilize the norm value to obtain a communication quality indicator. The electronic device may estimate a signal transmitted from the terminal (120) using the norm value. For example, the value estimated using the norm value (hereinafter, "estimated signal value") may be calculated using the following mathematical formula.

[0094]

[0095]

[0096] The terminal (120) can transmit DMRSs according to the DMRS configuration according to the network settings (e.g., RRC (radio resource control) signaling). Since the sequences of the DMRSs are predefined according to the DMRS configuration, an electronic device (e.g., base station (110), DU (210), RU (220)) that performs channel estimation can know in advance the sequences that would have been transmitted by the terminal (120). The electronic device can determine a communication quality index (e.g., SINR, SNR, CINR, EVM, BER, BLER) for the received signals by comparing the estimated signal values ​​estimated from the received signal with the transmitted signal values ​​corresponding to the predefined sequences. For example, the electronic device can compare an estimated vector having the estimated signal values ​​with a received vector having sequences according to the DMRS configuration. As an example, the electronic device can determine a communication quality index based on the following mathematical equation.

[0097]

[0098]

[0099] The communication quality index obtained through the above-described processes can be used for Doppler estimation. The electronic device can perform Doppler estimation according to the communication quality index. Hereinafter, in the present disclosure, the term of communication quality index is used to estimate the Doppler frequency, but in addition to these terms, it is to be understood that parameters indicating EVM parameter, communication quality, signal quality, reception quality, channel quality, quality index, error index, quality deviation, quality error, signal deviation, signal error, estimation error, estimation quality, and / or equivalent technical terms and / or equivalent meanings thereof can be used. For a specific description of the communication quality index, reference may be made to the constellation diagram described below.

[0100] Figures 8a and 8b show examples of constellations for received signals. The constellations represent signal vectors in complex space.

[0101] Referring to Fig. 8a, black dots represent actual transmitted signals (e.g., transmitted signal values), and white dots represent estimated signals (e.g., estimated signal values). For example, the transmitted signal may be modulated with QPSK. The transmitted signal may have candidate values ​​of '00', '01', '10', and '11'. For example, in a complex plane where the x-axis represents real numbers and the y-axis represents imaginary numbers, '00', '01', '10', and '11' may correspond to the first quadrant, the second quadrant, the third quadrant, and the fourth quadrant, respectively. The electronic device may determine a bit sequence corresponding to the estimated signal value (810) of the received signal depending on which quadrant the estimated signal value (810) is located in. The transmission signal values ​​(820) for '00', '01', '10', and '11' respectively correspond to 45 degrees, 135 degrees, 225 degrees, and 315 degrees in that order based on the (+) x-axis. Assuming an ideal wireless channel, the estimated signal value (810) also matches the transmission signal value (820), but this is not the case in an actual channel. Due to phase noise, carrier leakage, etc., the estimated signal value (810) may not exactly match the transmission signal value (820). At this time, the difference between the transmission signal value (820) and the estimated signal value (810) represents the error vector magnitude (EVM). In other words, the EVM represents the difference between ideal data and calculated data. The transmission signal value (820) corresponds to ideal data, and the estimated signal value (810) represents calculated data. The EVM may be a scalar value representing the accuracy of digital modulation. The smaller the difference between the transmitted signal value (820) and the estimated signal value (810), in other words, the lower the EVM, the better the channel condition may be.

[0102]

[0103] The denominator term (e.g., distance (840)) of the above [Mathematical Formula 7] represents the average of the transmission signal values ​​(820) for the subcarriers of the uplink frequency resource region. The numerator term (e.g., distance (860)) of the above [Mathematical Formula 7] represents the average of the differences between the transmission signal value (820) and the estimated signal value (810) for the subcarriers of the uplink frequency resource region.

[0104] Figures 9a and 9b illustrate examples of calculating communication quality using two RSs. The two RSs may include a first uplink reference signal and a second uplink reference signal. For example, the first uplink reference signal may be a DMRS mapped to symbol #2 (602) of the first slot, and the second uplink reference signal may be a DMRS mapped to symbol #11 (611) of the first slot. As another example, the first uplink reference signal may be a DMRS mapped to symbol #11 (611) of the first slot, and the second uplink reference signal may be a DMRS mapped to symbol #2 (652) of the second slot.

[0105] Doppler spread can be estimated by performing a correlation operation on the channel estimation results of temporally separated DMRS symbols (e.g., a first symbol to which a first uplink reference signal is mapped, a second symbol to which a second uplink reference signal is mapped). However, this method only roughly estimates the Doppler degree, making it difficult to estimate it accurately. In addition to the results of channel estimation, a direction to estimate the Doppler degree through the difference between two communication qualities can be considered. For example, the communication quality in the first symbol to which the first uplink reference signal is mapped can be calculated using the results of channel estimation using the first uplink reference signal and the first uplink reference signal. Similarly, the communication quality in the second symbol to which the second uplink reference signal is mapped can be calculated using the results of channel estimation using the second uplink reference signal and the second uplink reference signal. However, since this method assumes different channels between the two uplink reference signals, it is difficult to see that the difference in communication qualities directly represents the Doppler degree. Accordingly, the electronic device according to embodiments of the present disclosure can perform Doppler estimation by assuming the same channel vector for two communication qualities. Below, two communication quality indicators calculated in different ways are described in FIGS. 9A and 9B .

[0106] Referring to FIG. 9a, the electronic device receives a first uplink reference signal (901) (Y) from a terminal (e.g., terminal (120)). RS0 ) and the second uplink reference signal (911) (Y RS1 ) can be received. The first uplink reference signal (901) (Y RS0 ) and the second uplink reference signal (911) (Y RS1 ) represents signals received through multiple receiving antennas. More specifically, the first uplink reference signal (901) (Y RS0) represents the FFT output of the signals received in the first symbol to which the specified reference signal sequence is mapped. The second uplink reference signal (911) (Y RS1 ) represents the FFT output of signals received in the second symbol to which the specified reference signal sequence is mapped. The electronic device, through the equalization block (830), generates a first uplink reference signal (901) (Y RS0 ) and the first channel vector (903) (H RS0 ), using the first estimated signal value (905) (FEDout RS0 ) can be determined. The first channel vector (903) represents the result of channel estimation using the first uplink reference signal (901). For the equalization block (830), reference may be made to the descriptions of the equalization block (730) of FIG. 7. The electronic device, through the quality calculation block (840), calculates the first estimated signal value (905) (FEDout RS0 ) and the first transmission signal value (e.g., the first uplink reference signal (901) (Y RS0 ) can perform a comparison with the IQ value of the DMRS sequence to be assigned to the first symbol to which the first estimated signal value (905) (FEDout) is mapped. The electronic device RS0 ) and the difference between the first transmission signal values, the first communication quality index (907) (evmSNR RS0 ) can be calculated. For example, the electronic device can calculate the first communication quality index (907) (evmSNR) through [Mathematical Formula 6]. RS0 ) can be obtained. The first communication quality indicator (907) (evmSNR RS0 ) may represent a communication quality indicator in the first symbol to which the first uplink reference signal is mapped.

[0107] The above electronic device, through the equalization block (830), transmits a second uplink reference signal (911) (Y RS1 ) and the first channel vector (903) (H RS0), using the second estimated signal value (915) (FEDout RS1 ) can be determined. The first channel vector (903) represents the result of channel estimation using the first uplink reference signal (901). As described above, the electronic device may determine the second channel vector (H RS1 ) instead of using the first channel vector (H RS0 ) using the second estimated signal value (915) (FEDout RS1 ) can be determined. For the equalization block (830), reference may be made to the descriptions of the equalization block (730) of FIG. 7. The electronic device, through the quality calculation block (840), determines the second estimated signal value (915) (FEDout RS1 ) and the second transmission signal value (e.g., the second uplink reference signal (911) (Y RS1 ) can perform a comparison with the IQ value of the DMRS sequence to be assigned to the second symbol to which the second estimated signal value (915) (FEDout) is mapped. The electronic device RS1 ) and the difference between the second transmission signal values, the second communication quality index (917) (evmSNR RS1 ) can be calculated. For example, the electronic device can calculate the second communication quality index (917) (evmSNR) through [Mathematical Formula 6]. RS1 ) can be obtained. The second communication quality indicator (917) (evmSNR RS1 ) may represent a communication quality indicator in a second symbol to which a second uplink reference signal is mapped.

[0108] If the channel does not change over time, the Doppler spread can be 0. In other words, in a static environment, the first channel vector (903) (H RS0 ) and the second channel vector (H RS1 ) are the same. However, in a fading environment where the Doppler spread is not zero, the first channel vector (903) (H RS0 ) and the second channel vector (H RS1) can be inversely proportional to the Doppler. As the wireless channel environment changes rapidly, the correlation of the two channel vectors can decrease. As the wireless channel environment is stable, the correlation of the two channel vectors can increase. Assuming that the two channel vectors are the same, the influence due to Doppler according to time change can be estimated more accurately. For example, when estimating the second communication quality index in the second symbol to which the second uplink reference signal is mapped, the first channel vector (903) (H) according to the channel estimation using the first uplink reference signal RS0 ) can be used. Since the channel variation cannot keep up with the time gap between two symbols (e.g., the first symbol to which the first uplink reference signal is mapped, and the second symbol to which the second uplink reference signal is mapped), the communication quality index may be calculated lower than the actual value.

[0109] An electronic device according to embodiments can estimate the degree of Doppler spread through the difference (920) in the communication quality indices of the two symbols. Since the communication quality indices of different received signals from the two symbols are compared while assuming the same channel vector, the influence of channel variations is reduced, and thus, the Doppler influence due to time difference can be estimated more precisely. For example, the degree of Doppler spread can be obtained through the following mathematical formula.

[0110]

[0111]

[0112] In FIG. 9A, Doppler is estimated through mismatch using the second uplink reference signal (911) and the first channel vector (903), but embodiments of the present disclosure are not limited thereto. Estimating the degree of Doppler spread by applying the second channel vector, which is the result of channel estimation of the second uplink reference signal (911), to the first uplink reference signal (901) can also be understood as an embodiment of the present disclosure.

[0113] Referring to FIG. 9b, the electronic device receives a first uplink reference signal (951) (Y) from a terminal (e.g., terminal (120)). RS0 ) and the second uplink reference signal (961) (Y RS1 ) can be received. The first uplink reference signal (951) (Y RS0 ) and the second uplink reference signal (961) (Y RS1 ) represents signals received through multiple receiving antennas. More specifically, the first uplink reference signal (951) (Y RS0 ) represents the FFT output of the signals received in the first symbol to which the specified reference signal sequence is mapped. The second uplink reference signal (961) (Y RS1 ) represents the FFT output of signals received in the second symbol to which the specified reference signal sequence is mapped. The electronic device, through the equalization block (830), generates a first uplink reference signal (951) (Y RS0 ) and the second channel vector (953) (H RS1 ), using the first estimated signal value (955) (FEDout RS0 ) can be determined. The second channel vector (953) represents the result of channel estimation using the second uplink reference signal (961) instead of using the first uplink reference signal (951). As described above, the electronic device may determine the first channel vector (H RS0 ) instead of using the second channel vector (953)(H RS1) using the first estimated signal value (955)(FEDout RS0 ) can be determined. For the equalization block (830), reference may be made to the descriptions of the equalization block (730) of FIG. 7. The electronic device, through the quality calculation block (840), determines the first estimated signal value (955) (FEDout RS0 ) and the first transmission signal value (e.g., the first uplink reference signal (901) (Y RS0 ) can perform a comparison with the IQ value of the DMRS sequence to be assigned to the first symbol to which the first estimated signal value (905) (FEDout) is mapped. The electronic device RS0 ) and the difference between the first transmission signal values, the first communication quality index (957) (evmSNR RS0 ) can be calculated. For example, the electronic device can calculate the first communication quality index (957) (evmSNR) through [Mathematical Formula 6]. RS0 ) can be obtained. The first communication quality indicator (957) (evmSNR RS0 ) may represent a communication quality indicator in the first symbol to which the first uplink reference signal is mapped.

[0114] The above electronic device, through the equalization block (830), transmits a second uplink reference signal (961) (Y RS1 ) and the second channel vector (953) (H RS1 ), using the second estimated signal value (915) (FEDout RS1 ) can be determined. The second channel vector (953) represents the result of channel estimation using the second uplink reference signal (961). For the equalization block (830), reference may be made to the descriptions of the equalization block (730) of FIG. 7. The electronic device, through the quality calculation block (840), calculates the second estimated signal value (965) (FEDout RS1 ) and the second transmission signal value (e.g., the second uplink reference signal (961) (Y RS1) can perform a comparison with the IQ value of the DMRS sequence to be assigned to the second symbol to which the second estimated signal value (965) (FEDout) is mapped. The electronic device RS1 ) and the difference between the second transmission signal values, the second communication quality index (967) (evmSNR RS1 ) can be calculated. For example, the electronic device can calculate the second communication quality index (967) (evmSNR) through [Mathematical Formula 6]. RS1 ) can be obtained. The second communication quality indicator (967) (evmSNR RS1 ) may represent a communication quality indicator in a second symbol to which a second uplink reference signal is mapped.

[0115] An electronic device according to embodiments can estimate the degree of Doppler spread through the difference (970) in the communication quality indicators of the two symbols. For example, the degree of Doppler spread can be obtained through the following mathematical formula.

[0116]

[0117]

[0118] Figure 10 shows the difference in communication quality (e.g. SNR of [Equation 8]) Delta ) and the Doppler frequency.

[0119] Referring to Fig. 10, the graph (1000) shows the communication quality difference by Doppler frequency. The horizontal axis of the graph (1000) represents the Doppler frequency (unit: Hz), and the vertical axis of the graph (1000) represents the communication quality difference (unit: dB). The communication quality difference is expressed as the SNR of [Mathematical Formula 8]. DeltaCorresponds to. The first line (1001) represents the communication quality difference by Doppler frequency when the first communication quality index (907) is about 30 dB. The second line (1002) represents the communication quality difference by Doppler frequency when the first communication quality index (907) is about 20 dB. The third line (1003) represents the communication quality difference by Doppler frequency when the first communication quality index (907) is about 10 dB. The fourth line (1004) represents the communication quality difference by Doppler frequency when the first communication quality index (907) is about 0 dB. The fifth line (1005) represents the communication quality difference by Doppler frequency when the first communication quality index (907) is about -10 dB. The sixth line (1006) represents the communication quality difference by Doppler frequency when the first communication quality index (907) is about -20 dB.

[0120]

[0121] represents an estimated Doppler frequency, evmSNR represents a first communication quality index (907) for the first uplink reference signal, and func is a function corresponding to the relationship between evmSNR and the communication quality difference (hereinafter, the relationship function). The communication quality difference represents the difference between the first communication quality index (907) for the first uplink reference signal and the second communication quality index (917) for the second uplink reference signal.

[0122] Referring to the graph (1000), it can be confirmed that the relationship of the applied function changes according to the evmSNR. According to one embodiment, the electronic device can identify a relationship function according to a first communication quality index (907) for a first uplink reference signal among a plurality of relationship functions. The electronic device can determine a Doppler frequency according to a communication quality difference in two RS symbols using the determined relationship function. The communication quality difference can correspond to a difference between a first communication quality index using a first uplink reference signal and a channel vector of a first symbol and a second communication quality index using a second uplink reference signal and the channel vector of a second symbol. For example, the channel vector may be a first channel vector (e.g., a first channel vector (903)(H)) using the first uplink reference signal. RS0 ) may be. The second communication quality indicator may be calculated through mismatch. For another example, the channel vector may be a second channel vector (e.g., a second channel vector (953) (H) using the second uplink reference signal. RS1 )) can be calculated. The first communication quality indicator can be calculated through mismatch.

[0123] Figures 11a and 11b illustrate examples of the performance of Doppler estimation using correlation. Figures 11a and 11b illustrate the relationship between the correlation results obtained by correlating two channel vectors and the Doppler frequency.

[0124] Referring to FIG. 11a, a graph (1100) represents a cumulative distribution function (CDF) for each correlation result. The first line (1101) represents a CDF for each correlation result at a Doppler frequency of 10 Hz. The second line (1102) represents a CDF for each correlation result at a Doppler frequency of 50 Hz. The third line (1103) represents a CDF for each correlation result at a Doppler frequency of 100 Hz. The fourth line (1104) represents a CDF for each correlation result at a Doppler frequency of 200 Hz. The fifth line (1105) represents a CDF for each correlation result at a Doppler frequency of 300 Hz. The sixth line (1106) represents a CDF for each correlation result at a Doppler frequency of 400 Hz.

[0125] Referring to FIG. 11b, a graph (1150) represents a probability density function (PDF) for each correlation result. The first line (1151) represents a PDF for each correlation result at a Doppler frequency of 10 Hz. The second line (1152) represents a PDF for each correlation result at a Doppler frequency of 50 Hz. The third line (1153) represents a PDF for each correlation result at a Doppler frequency of 100 Hz. The fourth line (1154) represents a PDF for each correlation result at a Doppler frequency of 200 Hz. The fifth line (1155) represents a PDF for each correlation result at a Doppler frequency of 300 Hz. The sixth line (1156) represents a PDF for each correlation result at a Doppler frequency of 400 Hz.

[0126] Figures 12a and 12b show examples of the performance of Doppler estimation using communication quality.

[0127] Referring to Fig. 12a, a graph (1200) represents a cumulative distribution function (CDF) for each communication quality difference. The first line (1201) represents a CDF for each communication quality difference at a Doppler frequency of 10 Hz. The second line (1202) represents a CDF for each communication quality difference at a Doppler frequency of 50 Hz. The third line (1203) represents a CDF for each communication quality difference at a Doppler frequency of 100 Hz. The fourth line (1204) represents a CDF for each communication quality difference at a Doppler frequency of 200 Hz. The fifth line (1205) represents a CDF for each communication quality difference at a Doppler frequency of 400 Hz.

[0128] Referring to Fig. 12b, a graph (1250) represents a probability density function (PDF) for each communication quality difference. The first line (1251) represents a PDF for each communication quality difference at a Doppler frequency of 10 Hz. The second line (1252) represents a PDF for each communication quality difference at a Doppler frequency of 50 Hz. The third line (1253) represents a PDF for each communication quality difference at a Doppler frequency of 100 Hz. The fourth line (1254) represents a PDF for each communication quality difference at a Doppler frequency of 200 Hz. The fifth line (1255) represents a PDF for each communication quality difference at a Doppler frequency of 400 Hz.

[0129] In the present disclosure, for two symbols separated in time (e.g., DMRS symbols, SRS symbols), a communication quality index (e.g., a first communication quality index (907) (evmSNR) estimated without mismatch is provided. RS0 )) and communication quality indicators using mismatch (e.g., the second communication quality indicator (917) (evmSNR RS1)) is described as a technique for estimating the Doppler frequency. Instead of simply estimating the Doppler through a correlation operation of channel vectors (or channel matrices), a more quantitative estimation is possible because the Doppler is estimated by the difference in the communication quality indices. Comparing the graph (1100) of Fig. 11a with the graph (1200) of Fig. 12a, the difference between the Doppler frequencies is different when the variables (e.g., the correlation result and the communication quality difference) are different. For example, with a fixed CDF as a standard, for the differences between the same Doppler frequencies (e.g., 10 Hz and 100 Hz), the difference in the communication quality differences is greater than the difference in the correlation results. In other words, it can be confirmed that the communication quality is more advantageous than the correlation result in distinguishing the Doppler frequency. Similarly, comparing the graph (1150) of FIG. 11b with the graph (1250) of FIG. 12b reveals that when variables (e.g., correlation results and communication quality differences) vary, the differences between Doppler frequencies differ. For example, based on a fixed PDF, for differences between the same Doppler frequencies (e.g., 10 Hz and 100 Hz), the differences in communication quality differences are greater than the differences in correlation results. In other words, it can be confirmed that communication quality is more advantageous than correlation results in distinguishing Doppler frequencies.

[0130] Figure 13 illustrates the operational flow of an electronic device (e.g., DU (210), base station (110)) for determining Doppler spread information by utilizing differences in communication qualities. The Doppler spread information may represent parameters, indices, and / or values ​​associated with a Doppler frequency.

[0131] Referring to Figure 13,

[0132] In operation (1301), the electronic device may obtain first uplink reference signals of a first symbol. For example, the first uplink reference signals may be DMRSs. The DMRSs may be mapped to the first symbol. As another example, the first uplink reference signals may be SRSs. The electronic device, as a receiver of OFDM communication, may obtain the first uplink reference signals through an FFT operation (e.g., FFT block (710)) of signals received on the first symbol. The first uplink reference signals may correspond to subcarriers of an allocated uplink resource region of the first symbol on the time axis and on the frequency axis.

[0133] In operation (1303), the electronic device can obtain a first channel estimation result using the first uplink reference signals. The electronic device can perform channel estimation using the first uplink reference signals. The electronic device can perform channel estimation for each subcarrier for each of the plurality of receiving antennas. The electronic device can obtain a channel vector for each subcarrier for each of the plurality of receiving antennas.

[0134] In operation (1305), the electronic device may determine a first communication quality index based on the first uplink reference signals and the first channel estimation result. For example, the electronic device may identify a reception signal corresponding to a specific subcarrier among the first uplink reference signals. The electronic device may identify a channel vector corresponding to the specific subcarrier among the first channel estimation result. The electronic device may determine an estimated signal (e.g., an estimated signal value of [Mathematical Formula 6]) in the first symbol and the specific subcarrier using the reception signal and the channel vector. The electronic device may determine a transmission signal (e.g., a transmission signal value corresponding to predefined sequences) designated to be transmitted by a terminal (e.g., terminal 120) in the first symbol and the specific subcarrier. The electronic device may determine a difference between the transmission signal and the estimated signal for each subcarrier. The electronic device may determine a communication quality index using the difference. For example, the communication quality indicator may be evmSNR of [Mathematical Formula 7]. For another example, the communication quality indicator may be EVM, which may be proportional to the magnitude of the difference. For another example, the communication quality indicator may be indicated as a level corresponding to the difference among multiple levels.

[0135] In operation (1307), the electronic device may obtain second uplink reference signals of a second symbol. For example, the second uplink reference signals may be DMRSs. The DMRSs may be mapped to the second symbol. For another example, the second uplink reference signals may be SRSs. The second symbol may be a symbol mapped to transmit a reference signal (e.g., DMRS, SRS) after the first symbol. For example, referring to FIG. 6A, the first symbol, to which the first uplink reference signals are mapped, may correspond to symbol #2 (602) of the first slot, and the second symbol may correspond to symbol #11 (611) of the first slot. As another example, referring to FIG. 6B, the first symbol may correspond to symbol #11 (611) of the first slot as a symbol to which second uplink reference signals are mapped, and the second symbol may correspond to symbol #2 (652) of the second slot following the first slot. The electronic device, as a receiving end of OFDM communication, may obtain the second uplink reference signals through an FFT operation (e.g., FFT block (710)) of signals received on the second symbol. The second uplink reference signals may correspond to the second symbol on the time axis and subcarriers of an uplink resource region allocated on the frequency axis.

[0136] In operation (1309), the electronic device may determine a second communication quality index based on the second uplink reference signals and the first channel estimation result. For example, the electronic device may identify a received signal corresponding to a specific subcarrier among the second uplink reference signals. The electronic device may identify a channel vector corresponding to the specific subcarrier among the first channel estimation result. The electronic device may use the received signal and the channel vector to determine an estimated signal (e.g., an estimated signal value of [Mathematical Formula 6]) in the second symbol and the specific subcarrier. The electronic device according to embodiments may use the channel vector of the first channel estimation result that was previously used to determine the second communication quality index, rather than using the channel vector estimated through the second uplink reference signals. By determining the communication quality index through such mismatch, the degree of Doppler spread described below can be calculated more quantitatively. The electronic device may determine a transmission signal (e.g., a transmission signal value corresponding to predefined sequences) designated to be transmitted by a terminal (e.g., terminal 120) in the second symbol and the specific subcarrier. The electronic device may determine a difference between the transmission signal and the estimated signal for each subcarrier. The electronic device may determine a communication quality index using the difference. For example, the communication quality index may be evmSNR of [Mathematical Formula 7]. As another example, the communication quality index may be EVM, which may be proportional to the size of the difference. As another example, the communication quality index may be indicated as a level corresponding to the difference among a plurality of levels.

[0137] In operation (1311), the electronic device may determine Doppler spread information based on a difference between the first communication quality indicator and the second communication quality indicator. The Doppler spread information may represent a Doppler frequency. The Doppler frequency may be estimated through changes in the wireless channel environment between two symbols (e.g., the first symbol and the second symbol). A larger difference in the communication quality indicators of the two symbols may indicate a higher Doppler frequency. A smaller difference in the communication quality indicators of the two symbols may indicate a lower Doppler frequency. This is because, in reality, if the wireless channel changes less, the Doppler frequency may be measured lower. The electronic device may determine a difference between the first communication quality indicator and the second communication quality indicator. The electronic device may determine Doppler spread information based on the difference through a relationship function. The electronic device may identify a relationship function to be used among a plurality of relationship functions. For example, the electronic device may identify a relationship function to be used among the plurality of relationship functions based on the first communication quality indicator. For example, the electronic device may identify a relationship function to be used among the plurality of relationship functions based on the second communication quality indicator. The electronic device may determine the Doppler spread information by applying the difference to the identified relationship function.

[0138] The Doppler spread information estimated through FIG. 13 can be utilized in various ways. According to one embodiment, the electronic device can estimate a data channel based on the Doppler spread information. The electronic device can perform channel estimation for data symbols by reflecting the influence of the Doppler spread information. Furthermore, according to one embodiment, the electronic device can perform scheduling based on the Doppler spread information. For example, the electronic device can perform scheduling only for a frequency region in which the Doppler frequency is measured to be lower than a reference value. For example, the electronic device can determine a modulation and coding scheme (MCS) level based on the Doppler frequency. If the Doppler frequency is measured to be high and an environment in which the channel changes rapidly is expected, the electronic device can lower the MCS level and schedule the terminal to transmit data using a robust modulation scheme (e.g., QPSK). For example, the electronic device can determine whether to set frequency hopping based on the magnitude of the Doppler frequency. If a rapidly changing channel environment is expected, communication performance in the uplink channel can be improved through frequency hopping.

[0139] The utilization of the above-described Doppler spread information can be implemented in various ways depending on the distribution method of the network nodes. For example, DU (210) and RU (220) can be used to provide an access network. According to one embodiment, RU (220) can perform channel estimation using reference signals (e.g., DMRSs) and determine the Doppler spread information. Thereafter, RU (220) can transmit the Doppler spread information to DU (210). DU (210) can perform scheduling using the Doppler spread information. Furthermore, according to one embodiment, DU (210) can perform channel estimation using reference signals (e.g., DMRSs) and determine the Doppler spread information. Thereafter, DU (210) can perform scheduling using the Doppler spread information. In addition, according to one embodiment, the RU (220) can perform channel estimation using reference signals (e.g., DMRSs) and determine the Doppler spread information. Thereafter, the RU (220) can perform channel estimation for data symbols using the Doppler spread information. In addition, according to one embodiment, the DU (210) can perform channel estimation using reference signals (e.g., DMRSs) and determine the Doppler spread information. Thereafter, the DU (210) can perform channel estimation for data symbols using the Doppler spread information.

[0140] Although FIG. 13 illustrates that operation (1303) and operation (1305) are followed by operation (1307), embodiments of the present disclosure are not limited thereto. The order illustrated in FIG. 13 is merely an example, and operation (1307) may be performed before operation (1303) or operation (1305). In other words, the operation of acquiring the second uplink reference signals may be performed independently of the operation of acquiring the first channel estimation result or determining the first communication quality index.

[0141] Although FIG. 13 illustrates an example in which a network device (e.g., a base station (110), a DU (210), and an RU (220)) performing communication with a terminal (e.g., a terminal (120)) estimates an uplink channel, embodiments of the present disclosure are not limited thereto. Using the same principle, the terminal (120) can perform downlink channel estimation. The terminal (120) can determine a Doppler frequency for the downlink channel through a communication quality index according to mismatch with downlink reference signals in two symbols. For example, the terminal (120) can receive first downlink reference signals in a first symbol and second downlink reference signals in a second symbol. The terminal (120) can obtain a channel estimation result for the downlink channel through the first downlink reference signals. The channel estimation result can determine a channel matrix for the downlink channel between the terminal and a network node (e.g., a base station (110), an RU (220)). The terminal (120) can use the channel estimation result to determine first estimated signals for the first downlink reference signals. The terminal (120) can receive downlink configuration information (e.g., DMRS configuration information) from the network via RRC signaling. The terminal (120) can know in advance the downlink reference sequences in the first symbol. The terminal (120) can determine a first communication quality index for the first symbol by comparing the first estimated signals with the first transmission signals corresponding to the downlink reference sequences. The terminal (120) can use the channel estimation result to determine second estimated signals for the second downlink reference signals. A mismatch between a channel and a reference signal can be equally applied to the downlink. The terminal (120) can know in advance the downlink reference sequences in the second symbol according to the configuration information.The terminal (120) can determine a second communication quality index for the second symbol by comparing the second transmission signals corresponding to the downlink reference sequences with the second estimated signals. The terminal (120) can determine Doppler spread information by comparing the first communication quality index for the first symbol and the second communication quality index for the second symbol. The terminal (120) can perform channel estimation for the downlink data channel using the Doppler spread information.

[0142] Fig. 14a illustrates the functional configuration of a DU (digital unit). The configuration illustrated in Fig. 14a can be understood as the configuration of DU (210) of Fig. 14a as part of a base station. Terms such as "...unit" and "...unit" used hereinafter refer to a unit that processes at least one function or operation, and this can be implemented by hardware, software, or a combination of hardware and software.

[0143] Referring to FIG. 14a, DU (210) includes a transceiver (1410), memory (1420), and processor (1430).

[0144] The transceiver (1410) can perform functions for transmitting and receiving signals in a wired communication environment. The transceiver (1410) can include a wired interface for controlling direct connections between devices via a transmission medium (e.g., copper wire, optical fiber). For example, the transceiver (1410) can transmit electrical signals to other devices via copper wire, or perform conversion between electrical signals and optical signals. The DU (210) can communicate with the RU (radio unit) via the transceiver (1410).

[0145] The transceiver (1410) may perform functions for transmitting and receiving signals in a wireless communication environment. For example, the transceiver (1410) may perform a conversion function between baseband signals and bit streams according to the physical layer specifications of the system. For example, when transmitting data, the transceiver (1410) encodes and modulates the transmitted bit stream to generate complex symbols. Furthermore, when receiving data, the transceiver (1410) demodulates and decodes the baseband signal to restore the received bit stream. Furthermore, the transceiver (1410) may include multiple transmission and reception paths.

[0146] The transceiver (1410) can transmit and receive signals. For example, the transceiver (1410) can transmit management plane (M-plane) messages. For example, the transceiver (1410) can transmit management plane (S-plane) messages. For example, the transceiver (1410) can transmit control plane (C-plane) messages. For example, the transceiver (1410) can transmit user plane (U-plane) messages. For example, the transceiver (1410) can receive user plane messages. Although only the transceiver (1410) is illustrated in FIG. 14A, in other implementations, the DU (210) may include two or more transceivers.

[0147] The transceiver (1410) transmits and receives signals as described above. Accordingly, all or part of the transceiver (1410) may be referred to as a 'communication unit', a 'transmitter', a 'receiver', or a 'transmitter-receiver'. In addition, in the following description, transmission and reception performed through a wireless channel are used to mean that processing as described above is performed by the transceiver (1410). According to one embodiment, the transceiver (1410) may obtain random access signals related to an NPRACH on which physical layer processing has been performed from an RU (e.g., RU (220)). For example, the transceiver (1410) may obtain signals (e.g., frequency domain signals) on which CP removal and FFT have been performed on the received signals.

[0148] Although not illustrated in FIG. 14A, the transceiver (1410) may further include a backhaul transceiver for connection to the core network or other base stations. The backhaul transceiver may provide an interface for communicating with other nodes within the network. That is, the backhaul transceiver converts a bit stream transmitted from the base station to other nodes, such as other access nodes, other base stations, upper nodes, the core network, etc., into a physical signal, and converts a physical signal received from other nodes into a bit stream.

[0149] The memory (1420) stores data such as basic programs, application programs, and setting information for the operation of the DU (210). The memory (1420) may be referred to as a storage unit. The memory (1420) may be composed of volatile memory, non-volatile memory, or a combination of volatile and non-volatile memory. In addition, the memory (1420) may provide stored data upon request from the processor (1430).

[0150] The processor (1430) controls the overall operations of the DU (210). The processor (1480) may be referred to as a control unit. For example, the processor (1430) transmits and receives signals via the transceiver (1410) (or via the backhaul communication unit). In addition, the processor (1430) records and reads data from the memory (1420). In addition, the processor (1430) may perform functions of a protocol stack required by a communication standard. Although only the processor (1430) is illustrated in FIG. 14A, the DU (210) may include two or more processors according to other implementation examples.

[0151] According to one embodiment, the processor (1430) may perform physical layer processing on signals received from an RU (e.g., RU (220)). For example, the processor (1430) may perform subcarrier demapping (RE demapping) on ​​the received signals. For example, the processor (1430) may obtain a noise-interference component (e.g., a noise-interference covariance matrix) based on the received reference signals. Furthermore, for example, the processor (1430) may perform channel estimation based on the received reference signals. The processor (1430) may determine weights for a receive combiner. The processor (1430) may determine data corresponding to an uplink signal.

[0152] The configuration of DU (210) illustrated in FIG. 14a is merely an example, and examples of DUs performing embodiments of the present disclosure are not limited to the configuration illustrated in FIG. 14a. In some embodiments, some configurations may be added, deleted, or changed.

[0153] Fig. 14b illustrates the functional configuration of a wireless electronic device (e.g., RU (220), MMU). Hereinafter, RU (220) is exemplified as the wireless electronic device, but at least some of the descriptions described below may be applied to other wireless electronic devices. The configuration illustrated in Fig. 11b may be understood as the configuration of RU (220) of Fig. 2 as part of a base station. Terms such as "... unit" and "... device" used hereinafter mean a unit that processes at least one function or operation, and this may be implemented by hardware, software, or a combination of hardware and software.

[0154] Referring to FIG. 14b, the RU (220) includes an RF transceiver (1460), a fronthaul transceiver (1465), a memory (1470), and a processor (1480).

[0155] The RF transceiver (1460) performs functions for transmitting and receiving signals via a wireless channel. For example, the RF transceiver (1460) upconverts a baseband signal into an RF band signal and transmits the upconverted signal via an antenna, and downconverts an RF band signal received via the antenna into a baseband signal. For example, the RF transceiver (1460) may include a transmit filter, a receive filter, an amplifier, a mixer, an oscillator, a DAC, an ADC, and the like.

[0156] The RF transceiver (1460) may include multiple transmission and reception paths. Furthermore, the RF transceiver (1460) may include an antenna unit. The RF transceiver (1460) may include at least one antenna array composed of multiple antenna elements. In terms of hardware, the RF transceiver (1460) may be composed of digital circuits and analog circuits (e.g., a radio frequency integrated circuit (RFIC)). Here, the digital circuits and analog circuits may be implemented in a single package. In addition, the RF transceiver (1460) may include multiple RF chains. The RF transceiver (1460) may perform beamforming. The RF transceiver (1460) may apply beamforming weights to a signal to be transmitted and received in order to impart directionality to the signal according to the settings of the processor (1480). According to one embodiment, the RF transceiver (1460) may be equipped with multiple antennas.

[0157] According to one embodiment, the RF transceiver (1460) may transmit and receive signals over a radio access network. For example, the RF transceiver (1460) may transmit a downlink signal. The downlink signal may include a synchronization signal (SS), a reference signal (RS) (e.g., a cell-specific reference signal (CRS), a demodulation (DM)-RS), system information (e.g., a MIB, a SIB, remaining system information (RMSI), other system information (OSI)), a configuration message, control information, or downlink data. In addition, for example, the RF transceiver (1460) may receive an uplink signal. For example, the uplink signal may include a random access related signal (e.g., an NPRACH, an NPUSCH). According to one embodiment, the RF transceiver (1460) may receive signals including random access signals via multiple antennas provided in the RF transceiver (1460). Although only the RF transceiver (1460) is illustrated in FIG. 14B, according to other implementation examples, the RU (220) may include two or more RF transceivers.

[0158] The fronthaul transceiver (1465) can transmit and receive signals. According to one embodiment, the fronthaul transceiver (1465) can transmit and receive signals on the fronthaul interface. For example, the fronthaul transceiver (1465) can receive a management plane (M-plane) message. For example, the fronthaul transceiver (1465) can receive a management plane (S-plane) message. For example, the fronthaul transceiver (1465) can receive a control plane (C-plane) message. For example, the fronthaul transceiver (1465) can transmit a user plane (U-plane) message. For example, the fronthaul transceiver (1465) can receive a user plane message. In one embodiment, the fronthaul transceiver (1465) may transmit a signal (e.g., a frequency domain signal) on which CP removal and FFT have been performed to a DU (e.g., DU (210)). Although only the fronthaul transceiver (1465) is illustrated in FIG. 14B , in other implementations, the RU (220) may include two or more fronthaul transceivers.

[0159] The RF transceiver (1460) and the fronthaul transceiver (1465) transmit and receive signals as described above. Accordingly, all or part of the RF transceiver (1460) and the fronthaul transceiver (1465) may be referred to as a 'communication unit', a 'transmitter', a 'receiver', or a 'transmitter-receiver unit'. In addition, 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 RF transceiver (1460). 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 RF transceiver (1460).

[0160] The memory (1470) stores data such as basic programs, application programs, and setting information for the operation of the RU (220). The memory (1470) may be referred to as a storage unit. The memory (1470) may be composed of volatile memory, non-volatile memory, or a combination of volatile memory and non-volatile memory. In addition, the memory (1470) may provide stored data upon request from the processor (1480).

[0161] The processor (1480) controls the overall operations of the RU (220). The processor (1480) may be referred to as a control unit. For example, the processor (1480) transmits and receives signals through the RF transceiver (1460) or the fronthaul transceiver (1465). In addition, the processor (1480) writes and reads data to and from the memory (1470). In addition, the processor (1480) may perform functions of the protocol stack required by the communication standard. Although only the processor (1480) is illustrated in FIG. 14B, the RU (220) may include two or more processors according to other implementation examples. The processor (1480) may be a set of instructions or codes stored in the memory (1470), or may be a storage space that stores instructions / codes or instructions / codes that are temporarily residing in the processor (1480), or may be a part of the circuitry that constitutes the processor (1480). In addition, the processor (1480) may include various modules for performing communication. The processor (1480) may control the RU (220) to perform operations according to the embodiments described below.

[0162] The configuration of RU (220) illustrated in FIG. 14b is merely an example, and examples of RUs performing embodiments of the present disclosure are not limited to the configuration illustrated in FIG. 14b. In some embodiments, some configurations may be added, deleted, or changed.

[0163] In embodiments, an electronic device is provided. The electronic device may include at least one processor and a memory storing instructions. The instructions, when executed by the at least one processor, may cause the electronic device to obtain first uplink reference signals in a first symbol, obtain a first channel estimation result for the first symbol using the first uplink reference signals, obtain second uplink reference signals in a second symbol subsequent to the first symbol, determine a first communication quality index using the first uplink reference signals and the first channel estimation result for the first symbol, determine a second communication quality index using the second uplink reference signals and the first channel estimation result for the first symbol, and determine Doppler spread information corresponding to a difference between the first communication quality index and the second communication quality index.

[0164] For example, the first communication quality indicator may be determined based on a difference between a first estimated signal using the first channel estimation result for the first symbol and the first uplink reference signals and a first designated transmission signal for the first symbol. The second communication quality indicator may be determined based on a difference between a second estimated signal using the first channel estimation result for the first symbol and the second uplink reference signals and a second designated transmission signal for the second symbol.

[0165] For example, the first communication quality indicator may represent a ratio of the size of the first designated transmission signal to the size of the difference between the first estimated signal and the first designated transmission signal. The second communication quality indicator may represent a ratio of the size of the second designated transmission signal to the size of the difference between the second estimated signal and the second designated transmission signal.

[0166] For example, the first communication quality indicator can be determined according to the mathematical formula below.

[0167]

[0168]

[0169]

[0170]

[0171] For example, the first uplink reference signals may include demodulation reference signals (DMRSs) received from a terminal via a plurality of antennas on subcarriers of an uplink frequency resource region and the first symbol. The second uplink reference signals may include DMRSs received from a terminal via a plurality of antennas on the subcarriers of the uplink frequency resource region and the second symbol. The first channel estimation result for the first symbol may include a channel vector for each subcarrier of the subcarriers in the first symbol.

[0172] For example, the first estimated signal may be determined based on a received signal corresponding to the i-th subcarrier among the first uplink reference signals and a channel vector corresponding to the i-th subcarrier among the first channel estimation results for the first symbol, for the i-th subcarrier. The second estimated signal may be determined based on a received signal corresponding to the i-th subcarrier among the second uplink reference signals and a channel vector corresponding to the i-th subcarrier among the first channel estimation results for the first symbol, for the i-th subcarrier.

[0173] For example, each of the first estimated signal and the second estimated signal can be determined based on the mathematical formula below.

[0174]

[0175]

[0176] For example, the sequence of the first designated transmission signal in the first symbol and the sequence of the second designated transmission signal in the second symbol may be determined according to at least one parameter of demodulation reference signal (DMRS) configuration information provided to the terminal through radio resource control (RRC) signaling.

[0177] For example, the electronic device may include a digital unit (DU). The first uplink reference signals may be received from a terminal via a radio unit (RU) as first IQ (in-phase / quadrature-phase) data of first demodulation reference signals (DMRSs) mapped to the first symbol. The second uplink reference signals may be received from the terminal via the RU as IQ data of a second DMRS mapped to the second symbol.

[0178] For example, the electronic device may include a radio unit (RU). The first uplink reference signals may be received via a plurality of antennas of the RU on the first symbol. The second uplink reference signals may be received via the plurality of antennas of the RU on the second symbol.

[0179] For example, the instructions, when executed by the at least one processor, may cause the electronic device to obtain a second channel estimation result for the second symbol using the second uplink reference signals, and to obtain a channel estimation result for data symbols other than the first symbol and the second symbol using the first channel estimation result for the first symbol, the second channel estimation result for the second symbol, and the Doppler spread information.

[0180] For example, the instructions, when executed by the at least one processor, may cause the electronic device to determine a number of uplink reference symbols per slot according to the Doppler spread information and to transmit an RRC (radio resource control) message including demodulation reference signal (DMRS) configuration information indicating the number of uplink reference symbols per slot to the terminal.

[0181] For example, the difference between the first communication quality indicator and the second communication quality indicator may represent the Doppler spread information according to a relationship function. The relationship function may be identified among a plurality of relationship functions according to the first communication quality indicator.

[0182] In embodiments, a method performed by an electronic device is provided. The method may include: obtaining first uplink reference signals in a first symbol; obtaining a first channel estimation result for the first symbol using the first uplink reference signals; obtaining second uplink reference signals in a second symbol subsequent to the first symbol; determining a first communication quality index using the first uplink reference signals and the first channel estimation result for the first symbol; determining a second communication quality index using the second uplink reference signals and the first channel estimation result for the first symbol; and determining Doppler spread information corresponding to a difference between the first communication quality index and the second communication quality index.

[0183] For example, the first communication quality indicator may be determined based on a difference between a first estimated signal using the first channel estimation result for the first symbol and the first uplink reference signals and a first designated transmission signal for the first symbol. The second communication quality indicator may be determined based on a difference between a second estimated signal using the first channel estimation result for the first symbol and the second uplink reference signals and a second designated transmission signal for the second symbol.

[0184] For example, the first communication quality indicator may represent a ratio of the size of the first designated transmission signal to the size of the difference between the first estimated signal and the first designated transmission signal. The second communication quality indicator may represent a ratio of the size of the second designated transmission signal to the size of the difference between the second estimated signal and the second designated transmission signal.

[0185] For example, the sequence of the first designated transmission signal in the first symbol and the sequence of the second designated transmission signal in the second symbol may be determined according to at least one parameter of demodulation reference signal (DMRS) configuration information provided to the terminal through radio resource control (RRC) signaling.

[0186] For example, the method may further include an operation of obtaining a second channel estimation result for the second symbol using the second uplink reference signals, and an operation of obtaining a channel estimation result for data symbols other than the first symbol and the second symbol using the first channel estimation result for the first symbol, the second channel estimation result for the second symbol, and the Doppler spread information.

[0187] For example, the method may include an operation of determining the number of uplink reference symbols per slot according to the Doppler spread information, and an operation of transmitting an RRC (radio resource control) message including DMRS (demodulation reference signal) configuration information indicating the number of uplink reference symbols per slot to the terminal.

[0188] In embodiments, an electronic device is provided. The electronic device may include at least one processor and a memory storing instructions. The instructions, when executed by the at least one processor, may cause the electronic device to obtain first uplink reference signals in a first symbol, obtain second uplink reference signals in a second symbol subsequent to the first symbol, obtain a channel estimation result for the second symbol using the second uplink reference signals, determine a first communication quality index using the first uplink reference signals and the channel estimation result, determine a second communication quality index using the second uplink reference signals and the channel estimation result, and determine Doppler spread information corresponding to a difference between the first communication quality index and the second communication quality index.

[0189] In embodiments, an electronic device is provided. The electronic device may include at least one processor and at least one transceiver. The at least one processor may be configured to obtain first downlink reference signals in a first symbol via the at least one transceiver. The at least one processor may be configured to obtain a first channel estimation result for the first symbol using the first downlink reference signals. The at least one processor may be configured to obtain second downlink reference signals in a second symbol subsequent to the first symbol via the at least one transceiver. The at least one processor may be configured to determine a first communication quality index using the first downlink reference signals and the first channel estimation result for the first symbol. The at least one processor may be configured to determine a second communication quality index using the second downlink reference signals and the first channel estimation result for the first symbol. The at least one processor may be configured to determine Doppler spread information corresponding to a difference between the first communication quality indicator and the second communication quality indicator.

[0190] In embodiments, an electronic device is provided. The electronic device may include at least one processor and at least one transceiver. The at least one processor may be configured to obtain, via the at least one transceiver, first uplink reference signals in a first symbol. The at least one processor may be configured to obtain, via the at least one transceiver, second uplink reference signals in a second symbol subsequent to the first symbol. The at least one processor may be configured to obtain a channel estimation result for the second symbol using the second uplink reference signals. The at least one processor may be configured to determine a first communication quality index using the first uplink reference signals and the channel estimation result. The at least one processor may be configured to determine a second communication quality index using the second uplink reference signals and the channel estimation result. The at least one processor may be configured to determine Doppler spread information corresponding to a difference between the first communication quality index and the second communication quality index.

[0191] In embodiments, an electronic device is provided. The electronic device may include at least one processor and a memory storing instructions. The instructions, when executed by the at least one processor, may cause the electronic device to obtain first downlink reference signals in a first symbol, obtain a first channel estimation result for the first symbol using the first downlink reference signals, obtain second downlink reference signals in a second symbol subsequent to the first symbol, determine a first communication quality index using the first downlink reference signals and the first channel estimation result for the first symbol, determine a second communication quality index using the second downlink reference signals and the first channel estimation result for the first symbol, and determine Doppler spread information corresponding to a difference between the first communication quality index and the second communication quality index.

[0192] In embodiments, an electronic device is provided. The electronic device may include at least one processor and a memory storing instructions. The instructions, when executed by the at least one processor, may cause the electronic device to obtain first downlink reference signals in a first symbol, obtain second downlink reference signals in a second symbol subsequent to the first symbol, obtain a channel estimation result for the second symbol using the second downlink reference signals, determine a first communication quality index using the first downlink reference signals and the channel estimation result, determine a second communication quality index using the second downlink reference signals and the channel estimation result, and determine Doppler spread information corresponding to a difference between the first communication quality index and the second communication quality index.

[0193] For one or more embodiments, at least one of the components described in one or more of the preceding drawings may be configured to perform one or more operations, techniques, processes, and / or methods as described herein. For example, a processor (e.g., a baseband processor) described herein with respect to one or more of the preceding drawings may be configured to operate according to one or more examples described herein. For another example, circuitry associated with a user equipment (UE), a base station, a network element, and the like, as described above with respect to one or more of the preceding drawings, may be configured to operate according to one or more examples described herein.

[0194] Any of the embodiments described above may be combined with any other embodiment (or combination of embodiments) unless explicitly stated otherwise. The foregoing description of one or more implementations provides examples and descriptions, but is not intended to be exhaustive or limit the scope of the embodiments to the precise forms disclosed. Modifications and variations are possible in light of the above teachings or may be learned from practicing various embodiments.

[0195] The methods according to the embodiments described in the claims or specification of the present disclosure may be implemented in the form of hardware, software, or a combination of hardware and software.

[0196] When implemented in software, a computer-readable storage medium storing one or more programs (software modules) may be provided. The one or more programs stored in the computer-readable storage medium are configured to be executed by one or more processors in an electronic device. The one or more programs include instructions that cause the electronic device to execute methods according to embodiments described in the claims or specification of the present disclosure. The one or more programs may be provided as a computer program product. The computer program product may be traded between a seller and a buyer as a commodity. The computer program product may be distributed in the form of a machine-readable storage medium (e.g., compact disc read only memory (CD-ROM)), or may be distributed online (e.g., downloaded or uploaded) via an application store (e.g., Play Store™) or directly between two user devices (e.g., smart phones). In the case of online distribution, at least a portion of the computer program product may be temporarily stored or temporarily created in a device-readable storage medium, such as the memory of a manufacturer's server, an application store's server, or an intermediary server.

[0197] These programs (software modules, software) may be stored in random access memory, non-volatile memory including flash memory, read only memory (ROM), electrically erasable programmable read only memory (EEPROM), magnetic disc storage devices, compact disc-ROM (CD-ROM), digital versatile discs (DVDs) or other forms of optical storage devices, magnetic cassettes, or may be stored in memories formed by a combination of some or all of these. In addition, each configuration memory may include multiple copies.

[0198] Additionally, the program may be stored on an attachable storage device that is accessible via a communication network, such as the Internet, an intranet, a local area network (LAN), a wide area network (WAN), a storage area network (SAN), or a combination thereof. Such a storage device may be connected to a device implementing an embodiment of the present disclosure via an external port. Additionally, a separate storage device on the communication network may be connected to a device implementing an embodiment of the present disclosure.

[0199] In the specific embodiments of the present disclosure described above, components included in the disclosure are expressed singularly or plurally, depending on the specific embodiment presented. However, the singular or plural expressions are selected to suit the presented situation for convenience of explanation, and the present disclosure is not limited to singular or plural components. Components expressed in plural may be composed of singular elements, or components expressed in singular may be composed of plural elements.

[0200] According to embodiments, one or more of the components or operations of the aforementioned components may be omitted, or one or more other components or operations may be added. Alternatively or additionally, a plurality of components (e.g., modules or programs) may be integrated into a single component. In such a case, the integrated component may perform one or more functions of each of the plurality of components identically or similarly to those performed by the corresponding component among the plurality of components prior to the integration. According to embodiments, the operations performed by a module, program, or other component may be executed sequentially, in parallel, iteratively, or heuristically, or one or more of the operations may be executed in a different order, omitted, or one or more other operations may be added.

[0201] Meanwhile, although the detailed description of the present disclosure has described specific embodiments, it is obvious that various modifications are possible within the scope of the present disclosure.

Claims

1. In electronic devices, at least one processor; and Contains memory that stores instructions, When the above instructions are executed by the at least one processor, the electronic device: Obtaining the first uplink reference signals in the first symbol, Obtaining a first channel estimation result for the first symbol using the first uplink reference signals, Obtaining second uplink reference signals in the second symbol after the first symbol, Determine a first communication quality index using the first uplink reference signals and the first channel estimation result for the first symbol, Determine a second communication quality index using the second uplink reference signals and the first channel estimation result for the first symbol, causing Doppler spread information corresponding to the difference between the first communication quality indicator and the second communication quality indicator to be determined; Electronic devices.

2. In claim 1, The first communication quality indicator is determined based on the difference between the first estimated signal using the first channel estimation result for the first symbol and the first uplink reference signals and the first designated transmission signal for the first symbol, The second communication quality indicator is determined based on the difference between the second estimated signal using the first channel estimation result for the first symbol and the second uplink reference signals and the second designated transmission signal for the second symbol. Electronic devices.

3. In claim 2, The first communication quality indicator represents a ratio of the size of the first designated transmission signal to the size of the difference between the first estimated signal and the first designated transmission signal, The second communication quality indicator represents a ratio of the size of the second designated transmission signal to the size of the difference between the second estimated signal and the second designated transmission signal. Electronic devices.

4. In claim 3, The above first communication quality indicator is determined according to the mathematical formula below: The above second communication quality indicator is determined according to the mathematical formula below:

5. In claim 2, The above first uplink reference signals include subcarriers of an uplink frequency resource region and demodulation reference signals (DMRS) received from a terminal through a plurality of antennas on the first symbol, The second uplink reference signals include DMRSs received from a terminal via a plurality of antennas on the subcarriers and the second symbol of the uplink frequency resource region, The first channel estimation result for the first symbol includes a channel vector for each subcarrier of the subcarriers in the first symbol. Electronic devices.

6. In claim 5, The first estimated signal is determined based on a received signal corresponding to the i-th subcarrier among the first uplink reference signals and a channel vector corresponding to the i-th subcarrier among the first channel estimation results for the first symbol, for the i-th subcarrier. The second estimated signal is determined based on the received signal corresponding to the i-th subcarrier among the second uplink reference signals and the channel vector corresponding to the i-th subcarrier among the first channel estimation results for the first symbol, for the i-th subcarrier. Electronic devices.

7. In claim 6, Each of the first estimated signal and the second estimated signal is determined based on the mathematical formula below, 8. In claim 2, The sequence of the first designated transmission signal in the first symbol and the sequence of the second designated transmission signal in the second symbol are determined according to at least one parameter of the demodulation reference signal (DMRS) configuration information provided to the terminal through RRC (radio resource control) signaling. Electronic devices.

9. In claim 1, The above electronic device includes a DU (digital unit), The above first uplink reference signals are received from a terminal through a RU (radio unit) as first IQ (in-phase / quadrature-phase) data of first DMRS (demodulation reference signals) mapped to the first symbol, and The above second uplink reference signals are IQ data of the second DMRS mapped to the second symbol, received from the terminal through the RU. Electronic devices.

10. In claim 1, The above electronic device includes a RU (radio unit), The above first uplink reference signals are received via multiple antennas of the RU on the first symbol, The second uplink reference signals are received via the plurality of antennas of the RU on the second symbol. Electronic devices.

11. In claim 1, When the above instructions are executed by the at least one processor, the electronic device: Obtaining a second channel estimation result for the second symbol using the second uplink reference signals, Causing to obtain channel estimation results for data symbols other than the first symbol and the second symbol through the first channel estimation result for the first symbol, the second channel estimation result for the second symbol, and the Doppler spread information. Electronic devices.

12. In claim 1, When the above instructions are executed by the at least one processor, the electronic device: According to the above Doppler spread information, the number of uplink reference symbols per slot is determined, Causing the terminal to transmit an RRC (radio resource control) message including DMRS (demodulation reference signal) configuration information indicating the number of uplink reference symbols per slot. Electronic devices.

13. In claim 1, The difference between the first communication quality indicator and the second communication quality indicator represents the Doppler spread information according to the relationship function, The above relationship function is identified among a plurality of relationship functions according to the first communication quality indicator. Electronic devices.

14. In a method performed by an electronic device, An operation of acquiring first uplink reference signals in the first symbol, An operation of obtaining a first channel estimation result for the first symbol using the first uplink reference signals; An operation of acquiring second uplink reference signals in the second symbol after the first symbol, An operation for determining a first communication quality index using the first uplink reference signals and the first channel estimation result for the first symbol; An operation for determining a second communication quality index using the second uplink reference signals and the first channel estimation result for the first symbol; Including an operation of determining Doppler spread information corresponding to a difference between the first communication quality indicator and the second communication quality indicator. method.

15. In claim 14, The first communication quality indicator is determined based on the difference between the first estimated signal using the first channel estimation result for the first symbol and the first uplink reference signals and the first designated transmission signal for the first symbol, The second communication quality indicator is determined based on the difference between the second estimated signal using the first channel estimation result for the first symbol and the second uplink reference signals and the second designated transmission signal for the second symbol. method.

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