Method and apparatus for restricting channel estimation in the time domain for downlink transmission in a wireless communication system

Abstract

The present disclosure relates to a 5G communication system or a 6G communication system for supporting higher data rates beyond a 4G communication system such as long term evolution (LTE). The present disclosure relates to the field of a wireless communication system. More particularly, the present disclosure relates to method, apparatus(or device) and system for restricting channel estimation in the time domain for downlink transmission in a wireless communication system. A main technical result consists in enabling more flexible MU-MIMO scheduling in the time domain, including capabilities for more flexible channel estimation restrictions in the time domain, which ultimately leads to improved communication performance between the BS and the UE. Base station - implemented method of communication with one or more user equipments, the method comprising: defining possible values of a parameter of time interval of channel estimation performed by one or more UEs using one or more demodulation reference signals (DMRSs) for receiving a physical downlink shared channel (PDSCH); transmitting, using downlink control information (DCI) signaling, to the one or more UEs an indication of a scheduled PDSCH transmission and an indication of a to-be-applied value of said parameter from among the possible values of the parameter; and performing the scheduled PDSCH transmission to the one or more UEs.

Description

METHOD AND APPARATUS FOR RESTRICTING CHANNEL ESTIMATION IN THE TIME DOMAIN FOR DOWNLINK TRANSMISSION IN A WIRELESS COMMUNICATION SYSTEM

[0001] The present disclosure relates to the field of a wireless communication system. More particularly, the present disclosure relates to methods and apparatuses for restricting channel estimation in the time domain for downlink transmission in a wireless communication system.

[0002] Considering the development of wireless communication from generation to generation, the technologies have been developed mainly for services targeting humans, such as voice calls, multimedia services, and data services. Following the commercialization of 5G (5th generation) communication systems, it is expected that the number of connected devices will exponentially grow. Increasingly, these will be connected to communication networks. Examples of connected things may include vehicles, robots, drones, home appliances, displays, smart sensors connected to various infrastructures, construction machines, and factory equipment. Mobile devices are expected to evolve in various form-factors, such as augmented reality glasses, virtual reality headsets, and hologram devices. In order to provide various services by connecting hundreds of billions of devices and things in the 6G (6th generation) era, there have been ongoing efforts to develop improved 6G communication systems. For these reasons, 6G communication systems are referred to as beyond-5G systems.

[0003] 6G communication systems, which are expected to be commercialized around 2030, will have a peak data rate of tera (1,000 giga)-level bit per second (bps) and a radio latency less than 100μsec, and thus will be 50 times as fast as 5G communication systems and have the 1 / 10 radio latency thereof.

[0004] In order to accomplish such a high data rate and an ultra-low latency, it has been considered to implement 6G communication systems in a terahertz (THz) band (for example, 95 gigahertz (GHz) to 3THz bands). It is expected that, due to severer path loss and atmospheric absorption in the terahertz bands than those in mmWave bands introduced in 5G, technologies capable of securing the signal transmission distance (that is, coverage) will become more crucial. It is necessary to develop, as major technologies for securing the coverage, Radio Frequency (RF) elements, antennas, novel waveforms having a better coverage than Orthogonal Frequency Division Multiplexing (OFDM), beamforming and massive Multiple-input Multiple-Output (MIMO), Full Dimensional MIMO (FD-MIMO), array antennas, and multiantenna transmission technologies such as large-scale antennas. In addition, there has been ongoing discussion on new technologies for improving the coverage of terahertz-band signals, such as metamaterial-based lenses and antennas, Orbital Angular Momentum (OAM), and Reconfigurable Intelligent Surface (RIS).

[0005] Moreover, in order to improve the spectral efficiency and the overall network performances, the following technologies have been developed for 6G communication systems: a full-duplex technology for enabling an uplink transmission and a downlink transmission to simultaneously use the same frequency resource at the same time; a network technology for utilizing satellites, High-Altitude Platform Stations (HAPS), and the like in an integrated manner; an improved network structure for supporting mobile base stations and the like and enabling network operation optimization and automation and the like; a dynamic spectrum sharing technology via collision avoidance based on a prediction of spectrum usage; an use of Artificial Intelligence (AI) in wireless communication for improvement of overall network operation by utilizing AI from a designing phase for developing 6G and internalizing end-to-end AI support functions; and a next-generation distributed computing technology for overcoming the limit of UE computing ability through reachable super-high-performance communication and computing resources (such as Mobile Edge Computing (MEC), clouds, and the like) over the network. In addition, through designing new protocols to be used in 6G communication systems, developing mechanisms for implementing a hardware-based security environment and safe use of data, and developing technologies for maintaining privacy, attempts to strengthen the connectivity between devices, optimize the network, promote softwarization of network entities, and increase the openness of wireless communications are continuing.

[0006] It is expected that research and development of 6G communication systems in hyper-connectivity, including person to machine (P2M) as well as machine to machine (M2M), will allow the next hyper-connected experience. Particularly, it is expected that services such as truly immersive eXtended Reality (XR), high-fidelity mobile hologram, and digital replica could be provided through 6G communication systems. In addition, services such as remote surgery for security and reliability enhancement, industrial automation, and emergency response will be provided through the 6G communication system such that the technologies could be applied in various fields such as industry, medical care, automobiles, and home appliances.

[0007] The present disclosure relates generally to wireless communication systems. More specifically, the present disclosure is related to methods and apparatuses for restricting channel estimation in the time domain for downlink transmission in a wireless communication system.

[0008] According to an aspect of an exemplary embodiment, there is provided a communication method in a wireless communication system.

[0009] Aspects of the present disclosure provide efficient communication methods in a wireless communication system.

[0010] These and other aspects, features, and advantages of the present disclosure will be described in detail below with reference to the following accompanying figures. Where reference symbols are used, the same reference symbols in different figures denote the same objects. In the accompanying figures:

[0011] FIG. 1 illustrates a simplified diagram of the transceiving unit and antennas included in the BS and used to transmit PDSCH together with DMRS to UE and receive PUSCH together with DMRS from UE.

[0012] FIG. 2 illustrates the structure of type 1 DMRS in 5G NR.

[0013] FIG. 3 illustrates the structure of type 2 DMRS in 5G NR.

[0014] FIG. 4 is a flowchart of selecting PRG for PDSCH in 5G NR.

[0015] FIG. 5 is a flowchart of selecting a channel estimation time interval for PDSCH according to the present disclosure.

[0016] FIG. 6 is a non-limiting example of a PDSCH transmission structure according to the present disclosure.

[0017] FIG. 7 is the diagram of interactions between the BS and the UE according to an embodiment of the present disclosure.

[0018] FIG. 8 illustrates three non-limiting examples of PDSCH transmissions, for each of which its own time interval for estimating the PDSCH based on DMRS is set, according to an embodiment of the present disclosure.

[0019] FIG. 9 illustrates two non-limiting examples of setting time interval for estimating PDSCH based on DMRS according to an embodiment of the present disclosure.

[0020] FIG. 10 illustrates the schematic representation of the BS 200 according to an embodiment of the present disclosure.

[0021] FIG. 11 illustrates the schematic representation of the UE according to the present disclosure.

[0022] IG. 12 illustrates the schematic representation of communication system according to an embodiment of the present disclosure.

[0023] FIG. 13 is a block diagram of a terminal or user equipment (UE) according to an embodiment of the disclosure.

[0024] FIG. 14 is a block diagram of a base station (BS) according to an embodiment of the disclosure.

[0025] FIG. 15 is a block diagram of a network entity according to an embodiment of the disclosure.

[0026] Hereinafter, embodiments of the disclosure will be described in detail with reference to the accompanying drawings.

[0027] In describing the embodiments, descriptions related to technical contents well-known in the art and not associated directly with the disclosure will be omitted. Such an omission of unnecessary descriptions is intended to prevent obscuring of the main idea of the disclosure and more clearly transfer the main idea.

[0028] For the same reason, in the accompanying drawings, some elements may be exaggerated, omitted, or schematically illustrated. Further, the size of each element does not completely reflect the actual size. In the drawings, identical or corresponding elements are provided with identical reference numerals or different reference numerals.

[0029] The advantages and features of the disclosure and ways to achieve them will be apparent by making reference to embodiments as described below in detail in conjunction with the accompanying drawings. However, the disclosure is not limited to the embodiments set forth below, but may be implemented in various different forms. The following embodiments are provided only to completely disclose the disclosure and inform those skilled in the art of the scope of the disclosure, and the disclosure is defined only by the scope of the appended claims. Throughout the specification, the same or like reference numerals designate the same or like elements. Furthermore, in describing the disclosure, a detailed description of known functions or constitution incorporated herein will be omitted in the case that it is determined that the description may make the subject matter of the disclosure unnecessarily unclear. The terms which will be described below are terms defined in consideration of the functions in the disclosure, and may be different according to users, intentions of the operators, or customs. Therefore, the definitions of the terms should be made based on the contents throughout the specification.

[0030] Herein, it will be understood that each block of the flowchart illustrations, and combinations of blocks in the flowchart illustrations, may be performed based on computer program instructions. These computer program instructions may be loaded collectively onto at least one processor of a general purpose computer, special purpose computer, or other programmable data processing apparatus to produce a machine, such that the instructions, which perform through any one of, or in any combination of, the at least one processor of the computer or other programmable data processing apparatus, create means for performing the functions specified in the flowchart block(s). These computer program instructions may also be stored in a non-transitory computer usable or computer-readable memory that may direct a computer or other programmable data processing apparatus to function in a particular manner, such that the instructions stored in the computer usable or computer-readable memory produce an article of manufacture including instruction means that perform the function specified in the flowchart block(s). The computer program instructions may also be loaded onto a computer or other programmable data processing apparatus to cause a series of operational steps to be performed on the computer or other programmable data processing apparatus to produce a computer executed process such that the instructions that perform on the computer or other programmable data processing apparatus provide steps for executing the functions specified in the flowchart block(s).

[0031] Further, each block may represent a module, segment, or portion of code, which includes one or more executable instructions for executing the specified logical function(s). It should also be noted that in some alternative implementations, the functions noted in the blocks may occur out of the order. For example, two blocks(or functions) shown in succession may in fact be performed substantially concurrently or the blocks may sometimes be performed in the reverse order, depending upon the functionality involved.

[0032] As used in embodiments of the disclosure, a “~unit” may refer to a software element or a hardware element, such as a field programmable gate array (FPGA) or an application specific integrated circuit (ASIC), which performs a predetermined function. However, the term including the word “~unit” does not always have a meaning limited to software or hardware. The “~unit” may be constructed either to be stored in an addressable storage medium or to execute one or more processors. Therefore, the “~unit” includes, for example, software elements, object-oriented software elements, components such as class elements and task elements, processes, functions, properties, procedures, sub-routines, segments of a program code, drivers, firmware, micro-codes, circuits, data, database, data structures, tables, arrays, and parameters. The components and functions provided by the “~unit” may be either combined into a smaller number of components and a “~unit,” or divided into additional components and a “~unit.” Moreover, the components and “~units” may be implemented to reproduce one or more central processing units (CPUs) within a device or a security multimedia card. Further, in the embodiments, the “~unit” may include one or more processors.

[0033] It should be appreciated that the blocks in each flowchart and combinations of the flowcharts may be performed by one or more computer programs which include instructions. The entirety of the one or more computer programs may be stored in a single memory device or the one or more computer programs may be divided with different portions stored in different multiple memory devices.

[0034] Any of the functions or operations described herein can be processed by one processor or a combination of processors. The one processor or the combination of processors is circuitry performing processing and includes circuitry like an application processor (AP, e.g. a CPU), a communication processor (CP, e.g., a modem), a graphics processing unit (GPU), a neural processing unit (NPU) (e.g., an artificial intelligence (AI) chip), a Wi-Fi chip, a Bluetooth® chip, a global positioning system (GPS) chip, a near field communication (NFC) chip, connectivity chips, a sensor controller, a touch controller, a finger-print sensor controller, a display driver integrated circuit (IC), an audio CODEC chip, a universal serial bus (USB) controller, a camera controller, an image processing IC, a microprocessor unit (MPU), a system on chip (SoC), an IC, or the like.

[0035] It will be appreciated that various embodiments of the disclosure according to the claims and description in the specification can be realized in the form of hardware, software or a combination of hardware and software.

[0036] Any such software may be stored in non-transitory computer readable storage media. The non-transitory computer readable storage media store one or more computer programs (software modules), the one or more computer programs include computer-executable instructions that, when executed by one or more processors of an electronic device individually or collectively, cause the electronic device to perform a method of the disclosure.

[0037] Any such software may be stored in the form of volatile or non-volatile storage such as, for example, a storage device like read only memory (ROM), whether erasable or rewritable or not, or in the form of memory such as, for example, random access memory (RAM), memory chips, device or integrated circuits or on an optically or magnetically readable medium such as, for example, a compact disk (CD), digital versatile disc (DVD), magnetic disk or magnetic tape or the like. It will be appreciated that the storage devices and storage media are various embodiments of non-transitory machine-readable storage that are suitable for storing a computer program or computer programs comprising instructions that, when executed, implement various embodiments of the disclosure. Accordingly, various embodiments of the present disclosure may provide a program comprising code for implementing apparatus or a method as claimed in any one of the claims of this specification and a non-transitory machine-readable storage storing such a program.

[0038] Hereinafter, the determination of priority between A and B in the present disclosure may refer to various actions such as selecting the one having a higher priority based on a predefined priority rule and performing an operation corresponding thereto, or omitting or dropping an operation corresponding to the one having a lower priority.

[0039] Hereinafter, "A or B" as described in the present disclosure may be understood as "A and / or B," which may include A, or B, or both A and B.

[0040] In addition, "at least one of A, B, and C" as described in the present disclosure may be understood to include A, or B, or C, or any combination of A, B, and C.

[0041] In addition, "at least one of A, B, or C" as described in the present disclosure may be understood to include A, or B, or C, or any combination of A, B, and C.

[0042] Furthermore, "A / B" as described in the present disclosure may be understood as "A and / or B," which may include A, or B, or both A and B.

[0043] Furthermore, "A, B" as described in the present disclosure may be understood as "A and / or B," which may include A, or B, or both A and B.

[0044] Furthermore, "A and B" as described in the present disclosure may be understood as "A and / or B," which may include A, or B, or both A and B.

[0045] Furthermore, “if condition A and condition B are satisfied,” as described in the present disclosure, may not be limited to a case where both condition A and condition B are satisfied, but may be understood to include a case where either condition A or condition B is individually satisfied, both condition A and condition B are satisfied, or one or more additional conditions are satisfied in combination.

[0046] Furthermore, throughout this disclosure, ordinal terms such as "first," "second," "third," etc., (and similar qualifiers) are used merely to distinguish between different instances, occurrences, configurations, messages, stages, or aspects of elements, operations, or information as described herein. Unless the context clearly dictates otherwise, the use of such ordinal terms does not itself require that the elements, operations, or information distinguished by these terms be structurally different, numerically distinct, or substantively dissimilar. For example, a "first signal" and a "second signal" may refer to instances of the same signal transmitted at different times or containing the same core information despite minor variations, or they may refer to signals with different content or characteristics, depending on the specific context. Similarly, a "first value" and a "second value" may represent the same magnitude but measured or applied in different circumstances, or they may represent different magnitudes. The interpretation should be guided by the specific technical context, function, and relationship described in the relevant portion of the specification and claims.

[0047] Furthermore, the terms “first ~”, “second ~”, etc., as described in the present disclosure with respect to various elements (e.g., information, objects, operation, sequences, or the like), should not limit those elements. These terms may only be intended to distinguish one element from another, and may not be intended to indicate a specific order. For example, a first element could be termed a second element, and, similarly, a second element could be termed a first element.

[0048] Furthermore, even if “first ~” and “second ~” are described in the present disclosure, it may be understood that element(s) referred to by “first ~” and “second ~” may be the same or different. For example, in case of element(s) being information, first information and second information may both be same information and, in some cases, are separate and different information.

[0049] In addition, the terms “if ~” and “in case that ~” as used in the disclosure or claims may be interpreted to include the meanings of “when (or upon) ~,” “in response to ~,” “based on ~,” or “according to ~,” and may be used interchangeably with these expressions. In addition, expressions other than those exemplified herein may also be used, as long as they have substantially the same meaning and do not impair the technical features of the present disclosure.

[0050] For example, the physical layer signaling may be referred to as Layer 1 (L1) signaling and may include downlink control information (DCI). In addition, the higher layer signaling may include a medium access control (MAC) control message, a radio resource control (RRC) signaling message, a non-access stratum (NAS) signaling message, or an application layer message. The RRC signaling message may be referred to as L3 (layer 3) signaling. It should be noted, however, that the higher layer signaling is not limited to the aforementioned examples.

[0051] In addition, the term "not perform" as used in the present disclosure or claims may, in context, be understood to mean that the corresponding step is omitted or skipped. Such a term may be replaced with other terms having the same or substantially equivalent meaning.

[0052] In addition, "transmitting a message including A and B" as described in the present disclosure, may be understood as encompassing both (i) transmitting A and B in a single message, and (ii) transmitting A and B separately via multiple messages (e.g., transmitting a first message including A and a second message including B). This interpretation may also apply to messages that include two or more items (e.g., A, B, C), transmitted either together or separately.

[0053] In addition, "transmitting a message including A and transmitting a message including B" may also be interpreted as transmitting a message including A and B in a single message.

[0054] In the specific embodiments of the present disclosure described below, terms or components included in the disclosure may be expressed in singular or plural form depending on the specific embodiments presented. However, such singular or plural expressions are selected appropriately for convenience of description, and the present disclosure is not limited to a singular or plural number of components. A component expressed in the plural form may be implemented as a single component, and a component expressed in the singular form may be implemented as multiple components.

[0055] The drawings or flowcharts described below illustrate exemplary methods that may be implemented according to the principles of the present disclosure, and various modifications may be made to the methods illustrated in the flowcharts of the present disclosure. For example, although illustrated as a series of steps, various steps in each drawing or flowchart may overlap, occur in parallel, occur in a different order, or be repeated. In other examples, any step may be omitted or replaced with another step.

[0056] The methods and apparatuses proposed in the embodiments of the present disclosure are not limited to each embodiment individually, but may also be applied in combination of all or some of the embodiments proposed in the disclosure. Therefore, the embodiments of the present disclosure may be modified and applied without significantly departing from the scope of the present disclosure, as would be understood by those skilled in the art.

[0057] In this case, even if certain wordings are described differently across embodiments, they may be used interchangeably or in substitution or in combination if their underlying concepts are equivalent. For example, for the same or equivalent concept, even if one embodiment uses the expression "A" and another embodiment uses the expression "B", such expressions may be understood interchangeably, in substitution, or in combination.

[0058] The terms used in the following description to refer to access nodes, network entities, messages, interfaces between network entities, various types of identification information, and the like, are provided merely for the convenience of explanation by way of example. Therefore, the present disclosure is not limited to the terms described below, and other terms having equivalent technical meanings may also be used. Such terms may also be interchangeable with terms defined in any 3rd generation partnership project　(3GPP) technical specifications (TS) where appropriate.

[0059] Hereinafter, a base station is an entity that allocates resources to terminals, and may be at least one of a gNode B, an eNode B, a Node B, a base station (BS), a wireless access unit, a BS controller, or a node on a network.

[0060] Furthermore, the base station of the present disclosure may include a split architecture comprising a central unit (CU) and a distributed unit (DU). In this structure, the CU is configured to process the higher layers of the control and user planes, while the DU is configured to process lower-layer radio resource functions. The embodiments of the present disclosure may be equally applicable to 5G base station architectures in which such CU and DU functional splits are implemented.

[0061] A terminal may include a UE, a mobile station (MS), a cellular phone, a smartphone, a computer, or a multimedia system capable of performing communication functions.

[0062] In the disclosure, a downlink (DL) refers to a radio link through which a BS transmits a signal to a UE, and an uplink (UL) refers to a radio link through which a UE transmits a signal to a BS.

[0063] Furthermore, hereinafter, 5th generation (5G) mobile communication technologies (e.g., 5G new radio (NR)), 6th generation (6G) mobile communication technologies may be described by way of example, but the embodiments of the present disclosure may also be applied to other communication systems having similar technical backgrounds or channel types. For example, newly evolved mobile communication systems developed after 5G and 6G may be included. Furthermore, based on determinations by those skilled in the art, the embodiments of the present disclosure may also be applied to other communication systems (e.g., Wi-Fi systems) through some modifications without significantly departing from the scope of the present disclosure

[0064] In the following description, the terms physical channel and signal may be used interchangeably with data or control signal. For example, the term physical downlink shared channel (PDSCH) refers to a physical channel through which data is transmitted, but the term PDSCH may also be used to refer to the data itself. That is, in the present disclosure, the expression "transmit a physical channel" may be interpreted as being equivalent to the expression "transmit data or a signal via a physical channel."

[0065] Hereinafter, in the context of the present disclosure, higher layer signaling may refer to signaling corresponding to at least one or any combination of the following: master information block (MIB), system information block (SIB) or SIB M (M = 1, 2, ...), radio resource control (RRC), or medium access control (MAC) control element (CE), or a non-access stratum (NAS) signaling message, or an application layer message. The RRC signaling message may be referred to as L3 (layer 3) signaling.

[0066] In addition, L1 signaling may refer to signaling corresponding to at least one or any combination of signaling techniques using the at least one or any combination of the following physical layer channels or signaling: physical downlink control channel (PDCCH), downlink control information (DCI), user equipment (UE)-specific DCI, group-common DCI, common DCI, scheduling DCI (e.g., DCI used for scheduling downlink or uplink data), non-scheduling DCI (e.g., DCI not used for scheduling downlink or uplink data) physical uplink control channel (PUCCH), or uplink control information (UCI). The L1 signaling message may be referred to as a physical layer signaling.

[0067] Hereinafter, the expression that information is configured by the BS, as used in the present disclosure or claims, may, in context, be understood to mean that the terminal receives the corresponding information from the BS via a physical layer signaling or a higher layer signaling. Such an expression may be replaced with other terms having the same or substantially equivalent meaning.

[0068] Hereinafter, the operational principle of the present disclosure will be described in detail with reference to the accompanying drawings.

[0069] The 6G system operating in the high and mid-band (7-13 GHz) will support large MIMO (multiple input multiple output) antenna arrays with ≥ 1024 antenna elements, with hybrid analog and digital beamforming at BSs with a large number of antenna ports ≥ 128. Like 5G NR, 6G system is expected to support a similar set of reference signals such as DMRS (demodulation reference signal), CSI-RS (channel state information reference signal), SRS (sounding reference signal), PT-RS (phase tracking reference signal), PSS (primary synchronization signal), SSS (secondary synchronization signal). To ensure correct demodulation of the physical downlink and uplink shared channels (PDSCH and PUSCH), DMRS are used. DMRS are transmitted together with PDSCH and PUSCH, i.e. transmitted on demand, thus avoiding always-on signals. DMRS are subjected to precoding in the same way as PDSCH and PUSCH, i.e. DMRS have the same performance advantages as said physical data channels.

[0070] To provide more flexible scheduling and precoding of the downlink (DL) in the frequency domain, 5G NR supports a precoding resource group (PRG), which is a set of adjacent physical resource blocks (PRBs) in the frequency domain on which the BS applies the same precoding matrix (hereinafter referred to as the “precoder” for brevity). Thus, the UE can generally perform, for downlink demodulation, channel estimation within said PRG. In other words, if the PRG value is set, for example, to 2 adjacent PRBs, then the UE may perform channel estimation on each such PRB or on the two PRBs at once, and the use of the channel estimate obtained in this PRG for channel demodulation in the next PRG may lead to demodulation errors due to the channel “discontinuity” caused by the use of different precoders in these PRGs, i.e. in the next PRG the BS may have, for various reasons, changed the precoder used for DL transmission. Thus, the use of PRG allows minimizing errors caused by the “discontinuity” of the channel in the frequency domain.

[0071] It is anticipated that 6G communication technology will support PDSCH transmission with different transmission time intervals (TTIs) or with different time domain resource allocations (TDRAs), including those with durations greater than one slot. However, in 5G NR communication technology, the channel estimation restrictions and precoding assumptions for DMRS are supported only in the frequency domain. Thus, the channel estimation restrictions and DMRS precoding assumptions existing in prior art are not flexible enough. This gives rise to a number of problems that need to be addressed. Problem 1: The UE always assumes unrestricted channel estimates (which may also be referred to as channel measurements) for DMRS in the time domain. Problem 2: The time domain resource allocation of paired users, i.e. those users that are paired in a multi-user (MU) MIMO mode, must be aligned to ensure correct DL precoding / decoding. Problem 3: The current BS (i.e. the BS in 5G NR) will not be able to update the DL precoding within the PDSCH transmission in the transmission time interval even if its duration is more than 1 slot.

[0072] For the above reasons, the channel estimation and precoding restriction capabilities for DMRS need to be improved. In particular, the maximum time domain resource allocation (TDRA) for 6G xMIMO (extremely massive MIMO) will likely be extended beyond one slot (or 14 symbols). For such a long TDRA, more flexible MU-MIMO scheduling in the time domain should be supported. A possible change of DL precoding shall be signaled within the TDRA for PDSCH.

[0073] The present disclosure relates to the field of a wireless communication system. More particularly, the present disclosure relates to method, apparatus(or device) and system for restricting channel estimation in the time domain for downlink transmission in a wireless communication system.

[0074] Furthermore, the present disclosure relates to method, apparatus(or device) and system for communication between a base station (BS) and user equipments (UEs) that provide the ability to restrict channel estimation in the time domain for downlink transmission.

[0075] FIG. 1 illustrates a simplified diagram of the transceiving unit and antennas included in the BS and used to transmit PDSCH together with DMRS to UE and receive PUSCH together with DMRS from UE. FIG. 2 illustrates the structure of type 1 DMRS in 5G NR. FIG. 3 illustrates the structure of type 2 DMRS in 5G NR. FIG. 4 is a flowchart of selecting PRG for PDSCH in 5G NR.

[0076] DMRS for 5G NR are generated using pseudo-random sequences and are defined in 3GPP TS 38.211 for PDSCH and PUSCH. In 5G NR Rel-18 four types of DMRS are supported: type 1 DMRS, the structure of which is schematically illustrated in FIG. 2, type 2 DMRS, the structure of which is schematically illustrated in FIG. 3, as well as enhanced Type 1 (eType 1) DMRS and enhanced Type 2 (eType 2) DMRS.

[0077] As shown in FIG. 2, Type 1 DMRS has two code division multiplexing (CDM) groups, two frequency domain orthogonal cover codes (FD-OCCs), two time domain orthogonal cover codes (FD-OCCs) for a two-symbol DMRS configuration. In other words, type 1 DMRS supports a total of 2Х2Х2=8 orthogonal codes / 8 orthogonal DMRS ports that can be used for data transmission. Therefore, type 1 DMRS supports a maximum of eight ports for the two-symbol DMRS configuration. As shown in FIG. 2, for type 1 DMRS a uniform CDM group is used, i.e. the subcarriers used within the CDM group are distributed regularly.

[0078] As shown in FIG. 3, Type 2 DMRS has three code division multiplexing (CDM) groups, two frequency domain orthogonal cover codes (FD-OCCs), two time domain orthogonal cover codes (FD-OCCs) for a two-symbol DMRS configuration. In other words, type 2 DMRS supports a total of 3×2×2=12 orthogonal codes / 12 orthogonal DMRS ports that can be used for data transmission. Therefore, type 2 DMRS supports a maximum of twelve ports for the two-symbol DMRS configuration. As shown in FIG. 3, for type 2 DMRS a more localized CDM group is used, i.e. the subcarriers used within the CDM group are distributed in a more localized manner.

[0079] Type 1 DMRS and eType 2 DMRS are respectively the modifications of type 1 DMRS and type 2 DMRS, which are enhanced in that they use four FD-OCCs. Therefore, eType 1 DMRS and eType 2 DMRS respectively double the number of type 1 DMRS ports and the number of type 2 DMRS ports.

[0080] DL precoding for PDSCH follows the frequency domain granularity defined by the PRG size. In other words, it is assumed that the precoder applied to the corresponding (DL or UL) transmission will remain the same within a PRG in the frequency domain. PRG can take values of 2 PRB, 4 PRB or be wideband, i.e. cover the entire frequency domain resource allocation (FDRA). Possible PRG sizes may be specified in advance and the specific PRG size values to be used in a given case may then be signaled using RRC signaling and / or DCI signaling.

[0081] There are several reasons why a BS may decide to change the precoder. First, the transmission channel is frequency-selective and, accordingly, an optimal precoder in a given situation can change. Second, the frequency domain resource scheduler available in the communication network (e.g. as the part of the BS or in interaction with the BS) is attempted to be made more flexible; the system may contain multiple UEs and for the MU-MIMO mode, when several UEs are served on the same time-frequency resources, the scheduler may change the previously adopted decision: for example, for UE1 transmission (with a larger transmission packet, see packet 'B' in FIG. 6) all time-frequency resources are allocated, for the other user UE2 (with a smaller transmission packet, see packet 'A' in FIG. 6) a smaller part of the time-frequency resources (relative to the resources allocated to UE1) is allocated. That is, in the part of the resources MU-MIMO is used, and in the other part of the resources, in which transmission for UE1 is only performed, the single-user (SU) MIMO is used. In this non-limiting example, the BS can change the precoder as it transitions from operation in MU-MIMO to operation in SU-MIMO.

[0082] In general, it is usually impossible or difficult for the BS to communicate to the UE detailed information about how the BS allocates resources, or what precoder change scheme is used in a given case, since the BS must be flexible in these matters, or the precoder may change according to some complex algorithm. This is why the above-mentioned PRG is used for the frequency domain in 5G NR, where the UE assumes that the precoder will remain unchanged. Thus, PRG is understood here, and this understanding is consistent with 5G NR, as a resource block group consisting of a set of frequency-domain contiguous resource blocks that are contiguous resource blocks with a same pre-coding. However, the use of PRG in itself is not an obligation for the BS not to change the precoder, but rather a strong recommendation. In other words, the BS is not required to change the precoder even when PRG is used, meaning the frequency granularity of precoder changes never exceeds that of the PRG.

[0083] The PRG size selection procedure for PDSCH in 5G NR is schematically illustrated in FIG. 4 and described in detail in the specification Ref: TS 38.214 “NR; Physical layer procedures for data”, v18.2.0, 2024-03-29, 3gpp.org. The size of the PRG depends on a DCI format, i.e. the format of the downlink control information that is transmitted from the BS to the UE. As the non-limiting example, in 5G NR, the following PRG size determination logic is often used. If PDSCH transmission is scheduled using DCI format 1_0 signaling, then the PRG size value to be used in this scheduled PDSCH transmission will be derived as 'n2'=2 PRBs. Other possible values include, but are not limited to, 'n4'=4 PRBs, 'wideband'=all PRBs in FDRA for PDSCH. If the PDSCH transmission is scheduled by DCI format 1_1 signaling, then a semi-statically defined PRG size value will be derived according to RRC signaling or a dynamically defined PRG size value will be derived according to RRC signaling and DCI signaling.

[0084] There are two DCI formats: DCI format 1_0 and DCI format 1_1. The DCI format 1_0 is used for communication with the UE by default. This DCI format 1_0 is compact and fixed (i.e. its structure does not change). This DCI format 1_0 is used in cases where, for example, the UE is being reconfigured to enable initial communication with the UE. For this DCI format 1_0, a specific PRG size value may be specified in advance. In 5G NR, DCI format 1_0 has the PRG size specified in advance as 2. Thus, if, for example, the PDSCH is scheduled with DCI signaling having the format 1_0, then the UE may derive that the PRG size value is equal to, but not limited to, the predefined value 'n2' (i.e. two adjacent PRBs).

[0085] DCI format 1_1 is a more advanced format, the structure and size of which may vary depending on the UE configuration. The DCI signaling having DCI format 1_1 assumes in 5G NR, as shown in FIG. 4, that (1) the PRG size value is defined semi-statically via RRC signaling and (2) the PRG size value is defined dynamically via RRC and DCI signaling. When defined semi-statically, the PRG size value is determined according to the configured value that the UE receives from the RRC layer. When defined dynamically, the PRG size value is determined based on pre-configured values (of which there may be several) received from the RRC layer and, additionally, based on information contained in the DCI, namely in dependence on a number of PRBs that are allocated, according to the DCI, to the UE and a bit in the DCI.

[0086] The logic of defining / deriving the PRG size value semi-statically via RRC signaling is described in more detail below. In this embodiment, the UE may derive the PRG size according to the following pseudocode:

[0087] Pseudocode 1:

[0088]

[0089] The parameter 'PRG size' is the size of the PRG whose value is derived, and the parameter 'bundleSize' is a configuration parameter that is communicated to the UE through RRC signaling.

[0090] Next, the logic of defining the PRG size value dynamically through RRC and DCI signaling is described in more detail. In this embodiment, the PRG size may be derived according to the following pseudocode:

[0091] Pseudocode 2:

[0092]

[0093] The parameters 'bundleSizeSet1' and 'bundleSizeSet2' are communicated to the UE through RRC and may take one of the values specified above in Pseudocode 2 in curly brackets { }. The value of the 'N_PRBs' parameter in DCI specifies the number of PRBs allocated for data transmission. The value of the 'BWP size' parameter in DCI specifies the size of the channel bandwidth portion configured for the UE. In this embodiment, 1 bit in DCI is used to dynamically switch between the parameters 'bundleSizeSet1' and 'bundleSizeSet2', and the PRG size depends on the value of the parameter 'N_PRBs', i.e. the number of PRBs allocated for PDSCH. Given the derived PRG value, the UE performs channel estimation over each PRG or over a frequency domain unit that is smaller than one PRG (e.g. over a PRB). Due to this, the UE will, in most cases, avoid erroneous channel estimates due to a possible change in the precoder applied by the BS. The value 'n4' corresponds to 4 PRBs, the value 'wideband' corresponds to all PRBs (i.e. the entire FDRA for PDSCH), the value 'n2-wideband' corresponds to 2 PRBs or all PRBs, the value 'n4-wideband' corresponds to 4 PRBs or all PRBs. However, these values can be reassigned in other ways. Other details of the derivation of the PRG size value are described in technical specification TS 38.214 “NR; Physical layer procedures for data”, v18.2.0, 2024-03-29, 3gpp.org.

[0094] Next, considered with reference to FIG. 1 is the simplified diagram of the transceiving unit 200.1 and antennas 200.2 included in the BS 200 and used to transmit PDSCH together with DMRS to UE 400 and receive PUSCH together with DMRS from UE 400. On the left side of the figure, PDSCH / PUSCH transmissions for different MIMO layers and the DMRS antenna ports 'A', 'B', ..., 'ZZ' corresponding to said transmissions are shown. The number of MIMO layers usually corresponds to the number of DMRS ports and can be equal to, but not limited to, 64. Each transmission (e.g. PDSCH transmission for MIMO layer 'A') is transmitted with its corresponding DMRS signal transmitted from the corresponding DMRS antenna port (i.e. in this example from DMRS antenna port 'A'). On the receiving side of this transmission and the corresponding DMRS signal (for example the DMRS signal transmitted from the DMRS antenna port 'A'), the channel estimation is performed on the DMRS signal and the resulted estimate are used to demodulate the corresponding transmission (in this example the PDSCH transmission for MIMO layer 'A'). Each transmission, as shown in FIG. 1, is subjected in the transceiving unit 200.1 to digital and analog precoding and is emitted by a corresponding subset of physical antennas. In the present application, digital and analog precoding can be performed by any methods known from the prior art.

[0095] The present disclosure will now be described in the context of 6G communication system, bearing in mind the possibility of using in such a system data transmissions whose duration, namely TDRA, exceeds 1 slot or 14 OFDM symbols, since for xMIMO, from the point of view of implementation and overhead, it is highly desirable that the TDRA in MU-MIMO be sufficiently large.

[0096] There may be multiple OFDM symbols in the time domain in which DMRS (DMRS occasions) occur. Currently, the UE always assumes that the precoder will remain constant throughout the TDRA. That is, the UE may actually jointly process several DMRS symbols if they were transmitted from the BS within the TDRA several times, since there are configurations where DMRSs are transmitted several times in the time domain. At this time, the UE assumes that the precoder will not change in any way in the time domain within the slot, which leads to the problem that if the BS transmits data in a certain transmission mode (for example, in MU-MIMO), then it must maintain this mode throughout the entire TDRA, even if there is no longer any reason to use this mode in a part of the TDRA (i.e., for example, in said part of the TDRA it would be better to use SU-MIMO, since in said interval part the transmission is performed for single UE). This degrades the communication performance at least for some UEs (in the above non-limiting example for the UE, for which the transmission could have being performed in SU-MIMO, but is forced to be in MU-MIMO mode when there are no transmissions to other UEs in that TDRA). In other words, if the BS has the opportunity or need to change the precoder, or if for some other reason the BS has calculated a new optimal precoder value given the problem identified above, the BS cannot change the precoder because the UE assumes, or the BS knows that the UE assumes, that the precoder will not be changed during the entire TDRA.

[0097] In this disclosure, as indicated above, the possibility of transmitting a signal over longer than one slot (equal to 14 OFDM symbols) TDRA is considered (for example, over several adjacent slots or over a duration of more than 14 OFDM symbols). In such cases, the BS needs to have some flexibility for the scheduler so that when transmitting in MU-MIMO, it can change the data transmission to multiple UEs. For example, on some part of the exceeding 1-slot TDRA, the BS uses one MU-MIMO scheme, and on another arbitrary part of the TDRA (e.g., in the remaining part of the TDRA) - another MU-MIMO scheme or even another mode, i.e. SU-MIMO. Such a change in the MU-MIMO transmission scheme or the signal spatial coding mode itself entails a change in the precoder applied by the BS to the transmission.

[0098] In another non-limiting example, if there are UEs with different transmitted packet sizes, i.e. UE with a larger packet will use more time resources than another UE with a smaller packet. And the transmission to these two UEs, carried out in MU-MIMO mode, will entail a change in the scheduler decision for the time domain. In addition, for various reasons related to the computational delay at the BS, the calculation of the precoder at the BS based on the channel estimate reported by the UE takes some time and the BS, for various reasons, may not have time at the start of the transmission to calculate a most recent transmission precoder based on the most recent data. Therefore, it would be useful to give the BS the ability to change the downlink precoder based on the new channel estimates received.

[0099] To solve the above problems, the present disclosure proposes to use a “channel estimation time interval”, which is a group of symbols of (a same) precoding (precoding symbol group, PSG), on which the UE can assume the fixed precoder.

[0100] Next, with reference to Figs. 5-9, a detailed description will be given of the channel estimation time interval selection logic for the PDSCH and the communication method in which this logic is used according to the present disclosure.

[0101] FIG. 5 is a flowchart of selecting a channel estimation time interval for PDSCH according to the present disclosure. FIG. 6 is a non-limiting example of a PDSCH transmission structure according to the present disclosure. FIG. 7 is the diagram of interactions between the BS and the UE according to an embodiment of the present disclosure. FIG. 8 illustrates three non-limiting examples of PDSCH transmissions, for each of which its own time interval for estimating the PDSCH based on DMRS is set, according to an embodiment of the present disclosure. FIG. 9 illustrates two non-limiting examples of setting time interval for estimating PDSCH based on DMRS according to an embodiment of the present disclosure.

[0102] The BS-implemented method of communication with one or more UEs starts from defining, at step S100, possible values of the channel estimation time interval parameter. Channel estimation, to receive PDSCH, will be performed by one or more UEs on one or more DMRSs. The value of the channel estimation time interval parameter indicates a group of OFDM symbols (i.e. PSG) within which the UE expects no change by the BS of a precoder applied to the PDSCH transmission. In addition, it is necessary to note that the value of the channel estimation time interval parameter defines the granularity of the starting channel estimation time interval within the PDSCH transmission. As the non-limiting example, if the value of the channel estimation time interval is set to two DMRS occurrences in the TDRA (i.e., Y=2, as illustrated in FIG. 9 below), this means that in said TDRA (if its duration allows, i.e., at its duration of more than two DMRS occurrences) the next channel estimation time interval occurs every two DMRS occurrences. The defining at step S100 of possible values of the channel estimation time interval parameter includes configuring these values using RRC signaling or MAC signaling, or pre-specifying these values in a communication standard specification and storing the corresponding values in devices (e.g. in the memory of the BS and / or UE) to refer to them during operation.

[0103] The value of the channel estimation time interval parameter in one embodiment is defined by a total number of OFDM symbols included in the channel estimation time interval. In the non-limiting example, the channel estimation time interval parameter value may be set to 14 OFDM symbols, which would mean for the UE that the channel estimation time interval in the TDRA in this case would be a time period of 14 OFDM symbols from the beginning of that TDRA. In the other non-limiting example, the channel estimation time interval parameter value may be set to 7 OFDM symbols, which would mean for the UE that the channel estimation time interval in the TDRA in this case would be a time period of 7 OFDM symbols from the beginning of that TDRA. The values of 7 and 14 OFDM symbols given in the examples above should not be interpreted as limiting the present disclosure, since the channel estimation time interval can be set equal to OFDM symbol numbers that are less than or greater than 7, as well as OFDM symbol numbers that are less than or greater than 14.

[0104] In the alternative embodiment, the value of the channel estimation time interval parameter is defined by a number of OFDM symbols in the TDRA in which the DMRS occurs, i.e., the number of DMRS occurrences in the TDRA. In the non-limiting example, the value of the channel estimation time interval parameter may be set to 2 DMRS occurrences in the TDRA, which will mean for the UE that the channel estimation time interval in the TDRA in this case will be the time period starting with the first DMRS occurrence of said two DMRS, and ending with the second DMRS occurrence in the TDRA. Encountering the third DMRS occurrence in the TDRA will mark the end of the current PSG and the beginning of the next PSG. The number of OFDM symbols in the TDRA in which the DMRS occurs equal to 2, as indicated in the example above, should not be interpreted as limiting the present disclosure, since the channel estimation time interval may be set equal to a number of OFDM symbols in the TDRA in which the DMRS occurs, which is greater than or less than 2.

[0105] Once the step S100 is performed, the method proceeds to performing step S105, in which, using DCI signaling, one or more indications of a scheduled PDSCH transmission and a corresponding one or more indications of a to-be-applied value of said parameter from among previously defined possible values of this parameter are transmitted to one or more UEs. The indication of the to-be-applied value of said parameter from among the possible values of the parameter can be an explicit indication or an implicit indication of the value of said parameter.

[0106] A specific implicitly indicated value of said parameter is derived from the absence in the DCI of the explicit indication of any value of said parameter. In other words, if there is no explicit indication of any value of said parameter in the signaled DCI, the UE may derive the default value of the said parameter or any other predefined value. The non-limiting example of the default value of said parameter in this case could be the value 'allSymbols', i.e. the value that indicates to the UE that no change in the precoder applied by the BS is expected over the entire TDRA of the PDSCH being received. The specific value 'allSymbols' is not a limitation, since the default value of said parameter can be any other predefined value of said parameter (e.g. the value of the channel estimation time interval equal to 14 OFDM symbols or two DMRS occurrences in TTI or TDRA, etc.).

[0107] In the other embodiment, a specific implicitly indicated value of said parameter is derived from the absence in the DCI of an explicit indication of any value of said parameter and / or depending on a format of the signaled DCI. As shown in FIG. 5, scheduling of PDSCH transmission with DCI having DCI format 1_0 may implicitly indicate for the UE, but not limited to this specific value, the value 'wideband'. Scheduling of PDSCH transmission with DCI having DCI format 1_1 may result in (1) the channel estimation time interval value being semi-statically defined / derived through RRC signaling or (2) the channel estimation time interval value being dynamically defined / derived through RRC signaling and DCI. Deriving the channel estimation time interval value is performed on the UE side.

[0108] The logic of defining / deriving the channel estimation time interval value (i.e., PSG size) semi-statically through RRC signaling will now be described in more detail using the non-limiting example of the present disclosure implementation in this part. In this embodiment, the PSG size may be derived at the UE according to the following pseudocode:

[0109] Pseudocode 3:

[0110]

[0111] The parameter 'PSG size' is the PSG size measured in a number of DMRS symbols having a same precoding, the value of which is derived, and the parameter 'timeBundleSize' is a configuration parameter that is signaled to the UE through RRC signaling. The value 't2' may correspond to two DMRS occurrences (see item 1 in FIG. 8), the value 'all' may correspond to a total number of DMRS occurrences throughout the TDRA of the PDSCH transmission (i.e. over the entire TDRA), the value 't1' may correspond to a single DMRS occurrence. If the time interval value is defined by a total number of OFDM symbols in the TDRA rather than by a number of DMRS occurrences in the TDRA, then the value 't2' may correspond to OFDM symbols in the TDRA corresponding to two DMRSs (see the top of FIG. 9), the value 'all' may correspond to the total number of OFDM symbols in the TDRA, and the value 't1' may correspond to OFDM symbols corresponding to a single DMRS occurrence. However, neither the designations of specific values (i.e., 't2', 'all', 't1') nor the specific values themselves should be interpreted as any limitations of the present disclosure, since both the designations of specific values and the specific values themselves may be reassigned differently.

[0112] The logic of defining / deriving the channel estimation time interval value (i.e., PSG size) dynamically through RRC and DCI signaling will now be described in more detail using the non-limiting example of the present disclosure implementation in this part. In this embodiment, the PSG size may be derived according to the following pseudocode:

[0113] Pseudocode 4:

[0114]

[0115] The parameters 'timeBundleSizeSet1' and 'timeBundleSizeSet2' are communicated to the UE through RRC and may take one of the values specified above in Pseudocode 4 in curly brackets { }. The value of the 'N_symbols' parameter in DCI specifies the number of OFDM symbols allocated for data transmission, i.e. the number of OFDM symbols in TDRA. In the alternative implementation of said logic, the parameter 'N_symbols' may be replaced with the parameter 'N_DMRS_occasions' representing the number of DMRS occurrences in the time resources allocated for data transmission (e.g. in TDRA), and the parameter 'X' representing the threshold value of the number of OFDM symbols for PDSCH transmission may be correspondingly replaced with the parameter 'Y' representing the threshold number of DMRS occurrences. In this embodiment, 1 bit in DCI is used to dynamically switch between the parameters 'timeBundleSizeSet1' and 'timeBundleSizeSet2', and the PRG size depends on the value of the parameter 'N_symbols' or 'N_DMRS_occasions'. Given the derived PSG value, the UE performs channel estimation over each PSG or over a time domain unit that is smaller than a single PSG (e.g. over the part of OFDM symbols in which DMRS occur in TDRA). Due to this, the UE will in most cases perform channel estimation in consistency with changes in the precoder applied by the BS in the time domain.

[0116] The value 't2' may correspond to two DMRS occurrences, the value 'all' may correspond to a total number of DMRS occurrences throughout the TDRA of the PDSCH transmission (i.e. over the entire TDRA), the value 't1' may correspond to a single DMRS occurrence. If the time interval value is defined by a total number of OFDM symbols in the TDRA rather than by a number of DMRS occurrences in the TDRA, then the value 't2' may correspond to OFDM symbols in the PDSCH TDRA, which correspond to two DMRS occurrences, the value 'all' may correspond to all OFDM symbols in the TDRA, and the value 't1' may correspond to OFDM symbols in PDSCH TDRA, which correspond to a single DMRS occurrence. However, neither the designations of specific values (i.e. 't2', 'all', 't1') and parameters ('N_symbols', 'N_DMRS_occasions', 'X', 'Y'), nor the specific values themselves, including the specific values of the mentioned parameters, should be interpreted as any limitations of the present disclosure, since both the designations of specific values and the specific values themselves can be reassigned differently. In one embodiment, the BS scheduler may simultaneously perform both configuration and indication to the UE: of PRG (according to pseudocode 1 or 2) and configuration of PSG (according to pseudocode 3 or 4).

[0117] Thus, in one embodiment of the present disclosure, a specific implicitly indicated value of said parameter is derived from the absence in the DCI of an explicit indication of any value of said parameter and based on whether the time domain resources 'N_symbols' allocated for the PDSCH transmission exceed a corresponding threshold value X, where the value X is specified in advance in the specification of a communication standard (for example, but not limited to the mentioned value, X=14) or configured using higher layer signaling, wherein the time domain resources in this embodiment include a number of OFDM symbols.

[0118] In the other embodiment of the present disclosure a specific implicitly indicated value of said parameter is derived from the absence in the DCI of an explicit indication of any value of said parameter and based on whether the time domain resources 'N_slots' (this parameter is used in this embodiment instead of 'N_symbols') allocated for the PDSCH transmission exceed a corresponding threshold value X, where the value X is specified in advance in the specification of a communication standard (for example, but not limited to the mentioned value, X=1) or configured using higher layer signaling, wherein the time domain resources in this embodiment include a number of slots allocated in the time domain for PDSCH transmission.

[0119] In yet another embodiment of the present disclosure a specific implicitly indicated value of said parameter is derived from the absence in the DCI of an explicit indication of any value of said parameter and based on whether a number of occurrences of DMRS symbols 'N_DMRS_occasions' exceed a threshold value Y, where Y is specified in advance in a communication standard specification or configured using higher layer signaling.

[0120] In the alternative embodiment, the value of the channel estimation time interval parameter is explicitly indicated by one or more bits in the signaled DCI. Tables 1 and 2 below provide examples of explicit signaling of time domain configuration for channel estimation.

[0121]

[0122]

[0123] The correspondences between a specific bit value and a time domain configuration for channel estimation may be predefined in a communication standard specification and stored, for example in the form of a look-up table, in the memory of the BS and / or UE. Bit values greater than 2 bits can be used to support more codepoints. In addition, the DCI may further explicitly indicate for a scheduled PDSCH transmission the precoder change type with power reallocation (e.g., in steps: -3dB, 0dB, +3dB) or the precoder change type with full precoder recalculation. The precoder change type may be indicated by the same bit value (examples of which are given in Tables 1 and 2 above, i.e. in the same DCI field) that specifies the specific value of the channel estimation time interval parameter and will additionally, in this case, specify the specific precoder change type. Alternatively, the precoder change type may be indicated by a bit value in another DCI field (examples of which are given in Table 3 below), which will contain a bit value explicitly indicating only the precoder change type.

[0124]

[0125] The precoder change type with power reallocation may be signaled if on the PDSCH transmission duration the number of active UEs changes; for example, there are transmissions for UE#1 and UE#2, and from a specific OFDM symbol the signal transmission for UE#2 is not performed. In this case, the precoder change occurs, but it is only due to the fact that the amount of power allocated to the MIMO layer transmission to the UE#1 may be increased, in which case the BS 200 may signal via the DCI to UE#1 the precoder change type bit value '01' (according to Table 3 above) to dynamically reconfigure UE#1 to receive the PDSCH transmission with higher power. In this case, UE#1 understands that a simple power reallocation is taking place, and UE#1 may not perform a full channel re-estimation in this case, but may perform an appropriate scaling of the channel estimate obtained in the previous channel estimation time interval.

[0126] The precoder change type with full precoder recalculation, signaled by the precoder change type bit value '00' (as per Table 3 above), causes the UE to perform a full channel re-estimation. In this case, the UE understands that it is necessary to perform a complete channel re-estimation, and the UE in this case does not use the channel estimates that it obtained from the DMRS symbols of the previous channel estimation time interval, but performs a complete update of the channel estimate on the corresponding DMRS symbols of the recently arrived (i.e. current) channel estimation time interval.

[0127] Once the step S105 is performed, the method proceeds to performing step S110, in which the BS performs the scheduled PDSCH transmission(s) respectively to said one or more UEs. The non-limiting example of the structure of such a PDSCH transmission according to the present disclosure is illustrated in FIG. 6. In the situation shown in FIG. 6, the BS first transmits a PDSCH transmission-related packet 'A' to UE#2 and simultaneously transmits a PDSCH transmission-related packet 'B' to UE#1. Packet 'A' is smaller in size than packet 'B', so it takes up less time domain resources than packet 'B', i.e. TDRA of packet 'A' < TDRA of packet 'B'. Both transmissions shown are scheduled using DCI signaling with an explicit or implicit indication of PSG size being equal to two DMRS occurrences. This ensures configurable restrictions on the time-domain channel estimation performed by UEs on DMRSs, allowing the BS to more flexibly schedule the downlink in the time domain for different UEs. In the situation illustrated in FIG. 6, the BS has the opportunity to change (if the BS considers such a change necessary, for any reasons known to it) the precoder applied to the packet 'B' related to the PDSCH transmission to UE#1, and, optionally, to signal to the UE a specific precoder change type (as described above with respect to Table 3), starting with the third DMRS occurrence in the TDRA, while UE#1 will still be able to successfully demodulate the second half of the packet 'B', since it will recalculate the channel estimate on the third and, if necessary, fourth DMRS occurrence, which was signaled to it earlier by explicit or implicit indication of the PSG size being equal to two DMRS occurrences (as in the lower part of FIG. 9) and, optionally, the precoder change type.

[0128] Figs. 8, 9 show non-limiting examples of different configurations of time domain channel estimation restrictions signaled by the BS 200 and taken into account by UE 400 when performing channel estimation for demodulating PDSCH transmission.

[0129] Illustrated at the top of FIG. 8 is the PDSCH transmission in which there are four OFDM symbols in which DMRS occurs (i.e., four DMRS occurrences) on which the UE 400 will perform channel estimation. The channel estimation is restricted in the time domain in this case to two DMRS occurrences, i.e. the UE will perform channel re-estimation on every two DMRS occurrences in the PDSCH transmission time domain. The same restriction on the channel estimation time interval is illustrated in FIG. 9 below.

[0130] Illustrated at the middle of FIG. 8 is the PDSCH transmission that also has four DMRS occurrences. The channel estimation is restricted in the time domain in this case to a single DMRS occurrence, i.e. the UE will perform channel re-estimation on every new DMRS occurrence in the PDSCH transmission time domain.

[0131] FIG. 8 below illustrates the PDSCH transmission that also has four DMRS occurrences. In this case, the channel estimation in the time domain is not restricted (i.e. the value 'all' is signaled). In this case, the UE can theoretically use the channel estimate obtained from the front loaded (FL) DMRS to demodulate the PDSCH transmission over its entire time interval, since in this case the BS is not expected to change the precoder over the entire time interval of the PDSCH transmission.

[0132] FIG. 9 at the top illustrates the PDSCH transmission that also has four DMRS occurrences. The channel estimation is restricted in the time domain in this case to 14 OFDM symbols, i.e. the UE will perform the channel re-estimation on single or each new DMRS occurrence in the successive 14 OFDM symbols of the PDSCH transmission. In other words, the restriction of the channel estimation time interval can be defined not only by a number of DMRS occurrences, but also by a number of OFDM symbols. In the other alternative, the channel estimation time interval restriction can be defined by a number of slots.

[0133] FIG. 10 illustrates the schematic representation of the BS 200 according to an embodiment of the present disclosure.

[0134] Provided in a second aspect of the present disclosure is the BS 200 schematically shown in FIG. 10, which comprises operatively coupled a transceiving unit 200.1, an antenna 200.2, a processor 200.3, and a readable medium 200.4 storing instructions executable by the processor, which, when executed by the processor, cause the BS to perform the communication method according to the first aspect of the present disclosure or according to any development of the first aspect of the present disclosure. The BS 200 may be implemented as, but not limited to: Node B, eNodeB, gNodeB.

[0135] The transceiving unit 200.1 and the antenna 200.2 may generally correspond to what is illustrated in FIG. 1. The transceiving unit 200.1 and the antenna 200.2 can be adapted for operation in the upper part of the medium frequency band (7-13 GHz). The transceiving unit 200.1 is configured to transmit and receive radio signals. It includes amplifiers, modulators, demodulators and other components needed to convert signals to and from radio frequency band. The transceiving unit 200.1 can support multi-channel data transmission using xMIMO technology, which can increase the throughput. The transceiving unit 200.1 and the antenna 200.2 are responsible for digital and analog precoding / decoding of the signal. The transceiving unit 200.1 and the antenna 200.2 support operation in time division duplex mode and frequency division duplex mode, and comply with 3GPP specifications.

[0136] The antenna 200.2 is configured to emit and receive radio signals transmitted and received by transceiving unit 200.1. The antenna can be made in the form of an adaptive antenna array, which allows to steer the signal in a desired direction and minimize interference. As an example and not a limitation, the antenna 200.2 may have 1024 antenna elements and 128 digital ports. In the other example, the antenna 200.2 may have 3072 antenna elements and 256 digital ports. In yet another non-limiting example illustrated in FIG. 1 the antenna 200.2 may have 4096 antenna elements and 256 digital ports.

[0137] The processor 200.3 is responsible for processing all signals from all components of the BS 200 and for performing any step(s) of the above-described communication method according to the first aspect of the present disclosure or according to any development of the first aspect of the present disclosure. In other words, the processor 200.3 is configured to perform operations necessary to control the operation of the BS 200 and to execute executable instructions stored on the readable medium 200.4. The processor 200.3 in the BS 200 may be one or more of the following processors, but is not limited to the following types of processors: central processing units (CPUs), which are general-purpose processors that perform basic computing tasks in computers, servers, and mobile devices; graphic processing units (GPUs), which are specialized processors for processing graphics and performing parallel computing; coprocessors, which are auxiliary processors that operate in tandem with the CPU to perform specific tasks, such as, but not limited to, mathematical calculations or encryption; digital signal processors (DSPs), which are processors optimized for processing digital signals in real time, used in telecommunications and multimedia; systems on a chip (SoC), which are integrated chips that include, but are not limited to, a CPU, GPU, DSP, and other components, intended for mobile devices and embedded systems; microcontrollers (MCUs), which are compact processors with integrated memory and peripherals used in embedded systems and the IoT; field-programmable gate arrays (FPGAs), which are programmable processors that allow the user to configure their architecture to perform specialized tasks; neural processing units (NPUs), which are specialized processors optimized for machine learning and artificial intelligence tasks; vision processing units (VPUs), which are specialized microprocessors that are a type of AI accelerator designed to hardware accelerate the operation of machine vision algorithms.

[0138] The processor 200.3 may be manufactured using any technology known in the art, such as, but not limited to, CMOS technology, silicon-on-insulator (SOI) technology, silicon-germanium (SiGe) technology, gallium nitride (GaN) technology, graphene transistor technology, FinFET technology, GAAFET technology, etc. The processor 200.3 may be multi-core and support parallel data processing, which increases the operating efficiency of the BS 200.

[0139] Readable medium 200.4 is a storage device that stores executable instructions for processor 200.3. These instructions include instructions for performing the communication method according to the first aspect of the present disclosure or according to any development of the first aspect of the present disclosure, as well as any other instructions for controlling data transmission, signal processing, network resource management and other functions. The readable medium 200.4 in the BS 200 may be one or more of the following media, but without limitation to the types of media mentioned below: read-only memory (ROM), including, but without limitation, Mask ROM, PROM, EPROM, EEPROM; random access memory (RAM), including, but without limitation, DRAM, SDRAM, DDR SDRAM, MRAM, SRAM, PRAM, RRAM, FRAM, Nano-RAM, CBRAM nvSRAM; flash memory, including, but without limitation, NAND flash memory, NOR flash memory, USB flash memory; solid-state drives, including a drive (SSD), including, but without limitation, SATA SSD, NVMe SSD; optical discs, including, but without limitation, CD-ROM, DVD, Blu-ray; magnetic drives, including, but without limitation, HDD, magnetic tapes; memory cards, including but not limited to SD cards, microSD.

[0140] The readable medium 200.4 may be manufactured using any technology known in the art, such as, but not limited to, CMOS technology, silicon-on-insulator (SOI) technology, FinFET technology, 3D NAND technology, etc.

[0141] It should be understood that FIG. 10 does not show all components of the BS 200. In particular, in addition to the components shown, the BS 200 may contain other software and / or hardware components, such as, but not limited to, a power supply; a frequency-time resource scheduler implemented in software, hardware, or software and hardware and included in the BS 200 or located outside the BS 200, but in communication with it; a cooling system; input-output interfaces; switches and interconnections; a modulator / demodulator; a multiplexer / demultiplexer; filters; power control circuits; an operating system (OS) and other software. The BS 200 may be referred to by other names, such as a transmit / receive point (TRP).

[0142] Provided in the third aspect of the present disclosure is the computer-readable medium storing executable instructions that, when executed by a device, cause the device to perform the communication method according to the first aspect of the present disclosure or according to any development of the first aspect of the present disclosure. The readable medium may correspond to the readable medium 200.4 described above, so its repeated description is not repeated here. The instructions may be in any language and be presented in any form, provided that such language and form of instructions can be perceived by the processor 200.3 and other equipment of the BS 200 and the instructions can be executed to perform the communication method according to the first aspect of the present disclosure or according to any development of the first aspect of the present disclosure, or to implement any other necessary functionality.

[0143] Next, with reference to Figs. 5 and 7, the description of the UE-implemented method of communication with the BS is given. The communication method starts with step S300, in which an indication of a scheduled PDSCH transmission and an indication of a to-be-applied value of channel estimation time interval parameter from possible (pre-configured) values of said parameter are received using DCI signaling. Technically, the reception of the transmission by the UE 400 can be implemented according to any method known in prior art, at least with the aid of the components illustrated in FIG. 1 and FIG. 11. The DCI signaling and the derivation of the explicitly indicated and implicitly indicated channel estimation time interval parameter value may be performed similarly to what is described above with reference to Tables 1-3 and Pseudocodes 3-4, so the detailed description of these features of the present disclosure is not given here again.

[0144] Once the step S300 is performed, the UE 400 performs step S305, in which the channel estimate is calculated from one or more DMRS occurrences within the PDSCH transmission channel estimation time interval indicated by the received value of said parameter, and then step S310, in which the UE 400 performs demodulation of the PDSCH transmission based on the channel estimate obtained. The estimation of channel based on DMRS and demodulation of the transmission themselves may be performed by any known prior art methods, such as, but not limited to, any methods used in 5G NR for estimating channel between BS and UE from DMRS and demodulating the transmission.

[0145] Similar to the communication method implemented by the BS 200 described above with reference to Figs. 5 and 7, Tables 1-3 and Pseudocodes 1-4, the value of the channel estimation time interval parameter indicates a group of symbols within which the UE 400 expects no change by the BS 200 of the precoder applied to the PDSCH transmission, where the symbols are OFDM symbols. The value of the channel estimation time interval parameter is defined by a total number of OFDM symbols contained in the channel estimation time interval, or by a number of OFDM symbols in which DMRS occurs, within the TTI / TDRA, where the UE 400 expect no change by the BS 200 of the precoder applied to the PDSCH transmission.

[0146] Possible values of said parameter are configured for and derived at the UE 400 via RRC signaling or MAC signaling. Possible values of said parameter are specified in advance in a specification of a communication standard and are derived at the UE 400 in accordance with such specification. The indication to the UE 400 of a to-be-applied value of said parameter from possible values of the parameter by the BS 200 may be received at the UE 400 as explicit indication of the specific value of this parameter (e.g. a bit value in a specific DCI field) or be implicit logical derivation of the value based on indirect parameters (e.g. depending on a format of the DCI received at the UE 400, or depending on the above-described parameters 'N_symbols', 'N_DMRS_occasions', 'X, 'Y', etc.).

[0147] Thus, in the embodiment of the method implemented by the UE 400 a specific implicitly indicated value of the parameter is derived at the UE from the absence in the DCI of an explicit indication of any value of said parameter. In this case, the specific implicitly indicated value of said parameter may be the default value of this parameter or another predefined value. The default value of said parameter may indicate for the UE that no change in the precoder applied by the BS is expected over the entire PDSCH transmission time interval. In yet another embodiment a specific implicitly indicated value of said parameter is derived at the UE from the absence in the DCI of an explicit indication of any value of said parameter and / or depending on a format of the signaled DCI.

[0148] In yet another embodiment of the method a specific implicitly indicated value of said parameter is derived at the UE from the absence in the DCI of an explicit indication of any value of said parameter and / or based on whether the time domain resources allocated for the PDSCH transmission exceed a threshold value specified in advance in a specification of a communication standard or configured using higher layer signaling, wherein the time domain resources include a number of OFDM symbols or a number of slots in PDSCH transmission. In yet another embodiment of the method a specific implicitly indicated value of said parameter is derived at the UE from the absence in the DCI of an explicit indication of any value of said parameter and / or based on whether a number of occurrences of DMRS symbols exceed a threshold value specified in advance in a specification of a communication standard or configured using higher layer signaling. To explicitly indicate the value of said parameter in the DCI one or more bits are allocated (see Tables 1-2 above). In the other embodiment, said method further comprises receiving an explicit indication for the scheduled PDSCH transmission, using DCI signaling (see Table 3 above), of a precoder change type with power reallocation or the precoder change type with full precoder recalculation.

[0149] FIG. 11 illustrates the schematic representation of the UE according to the present disclosure.

[0150] Provided in a fifth aspect of the present disclosure is the UE 200 schematically shown in FIG. 11, which comprises operatively coupled a transceiving unit 400.1, an antenna 400.2, a processor 400.3, and a readable medium 400.4 storing instructions executable by the processor, which, when executed by the processor, cause the UE to perform the communication method according to the fourth aspect of the present disclosure or according to any development of the fourth aspect of the present disclosure.

[0151] The UE 400 includes various user electronic devices that are connected to telecommunication networks to gain access to various services and functions. Thus, the UE 400 may be, but is not limited to, a smartphone, a tablet, a smart watch, smart glasses, a fitness tracker, an augmented reality (AR) and / or virtual reality (VR) headset, a laptop, a desktop computer, a mini PC, a smart TV, a streaming media device, a medical device, a payment processing device, equipment installed on a vehicle, including an entertainment system, an Internet of Things (IoT) device, a smart sensor, a monitoring device, etc. The UE 400 may be referred to differently, such as a user terminal, a terminal, a user device, a mobile device, etc.

[0152] The description of possible implementations of the transceiving unit 200.1, antenna 200.2, processor 200.3, and readable medium 200.4 contained in the BS 200 are essentially applicable, mutatis mutandis, respectively, as the descriptions of possible implementations of the transceiving unit 400.1, antenna 400.2, processor 400.3, and readable medium 400.4 contained in the UE 400. Therefore, such descriptions are not repeated here.

[0153] Provided in the sixth aspect of the present disclosure is the computer-readable medium storing executable instructions that, when executed by a device, cause the device to perform the communication method according to the fourth aspect of the present disclosure or according to any development of the fourth aspect of the present disclosure. The description of possible implementations of the readable medium 200.4 is essentially applicable, mutatis mutandis, as the description of the readable medium according to the sixth aspect of the present disclosure. Therefore, it is not described here again. The instructions may be in any language and be presented in any form, provided that such language and form of instructions can be perceived by the processor 400.3 and other components of the UE 400 and the instructions can be executed to perform the communication method according to the fourth aspect of the present disclosure or any development of the fourth aspect of the present disclosure, or to implement any other necessary functionality.

[0154] FIG. 12 illustrates the schematic representation of communication system 500 according to an embodiment of the present disclosure. The communication system 500 comprises one BS 200, which is installed to serve UEs 400 in three deployed cells 1, 2, 3. The BS may correspond to the BS 200 described in detail above with reference to FIG. 10, and each UE may correspond to the UE 400 described in detail above with reference to FIG. 11, so detailed descriptions of the BS 200 and the UE 400 are not given here again. The communication system 500 may simultaneously support several active radio access technologies (RATs) such as 4G LTE, 5G NR, 6G.

[0155] The specific details shown in FIG. 11 should not be considered as limitations of the present technology, since the system 500 may have a different architecture and be characterized / illustrated differently, for example, each cell of cell 1, cell 2, cell 3 may have its own BS 200, the number of UEs 400 in the cells may differ from that shown, cells 1, 2, 3 may represent one larger cell, the shape and space covered by the cells may differ from that shown, etc. The number of cells may be greater or less than 3.

[0156] FIG. 13 is a block diagram of a terminal or user equipment (UE) 1300 according to an embodiment of the disclosure. Furthermore, the UE of FIG. 13 corresponds to the UE of FIG. 11.

[0157] The terminal is an electronic device capable of wireless communication, may include a User Equipment (UE), a portable phone, a smartphone, a tablet, an Internet of things (IoT) device, etc., having various form factors, and may perform wireless communication with a base station (BS) through a wireless channel.

[0158] Referring to FIG. 13, the UE 1300 may include at least one transceiver (hereinafter, referred to as simply “transceiver”) 1301, at least one processor (hereinafter, referred to as simply “processor”) 1302, and at least one memory (hereinafter, referred to as simply “memory”) 1303. According to at least one or a combination of methods corresponding to the embodiments described in the present disclosure, the transceiver 1301, the processor 1302, and the memory 1303 of the UE 1300 may operate. However, components of the UE 1300 are not limited to the exemplary components illustrated in FIG. 13. In another embodiment, the UE 1300 may further include additional components in addition to the above-mentioned components, or some components may be omitted. Further, in some embodiments, any combination of the transceiver 1301, the processor 1302, or the memory 1303 may be integrated in the form of one component.

[0159] The transceiver 1301 may be a communication circuit or communication circuitry that enables the UE 1300 to perform wireless communication with a node or an entity of a network. For example, the transceiver 1301 may enable the UE 1300 to transmit or receive a signal to or from a BS through cellular communication, or to transmit or receive a signal to or from another UE through cellular communication. For example, the transceiver 1301 may support at least one of various cellular communication technologies including 3rd generation (3G), 4th generation (4G), long term evolution (LTE), 5th generation (5G) NR, 6th generation (6G), and various cellular wireless communication technologies supported by the transceiver (1301) may include all subsequent generations of evolved wireless communications.

[0160] According to an embodiment, the UE 1300 may include a plurality of transceivers. For example, in the case of supporting evolved-universal terrestrial radio access-new radio (E-UTRA-NR) sual connectivity (EN-DC), the UE 1300 may include a first transceiver supporting the 4G LTE wireless communication and a second transceiver supporting the 5G NR wireless communication. According to another embodiment, in the case of supporting NR-dual connectivity (NR-DC), the UE 1300 may include a plurality of transceivers supporting the 5G NR wireless communication. According to still another embodiment, in the case of supporting near field wireless communication, the UE 1300 may separately include a transceiver supporting at least one standard in the group of wireless communication protocol standards as defined in the protocol standards for Bluetooth®, wireless local area network (WLAN) network (including institute of electrical and electronics engineers (IEEE) 802.11-2016 standard or its amendments, e.g., 802.11ah, 802.11ad, 802.11ay, 802.11ax, 802.11az, 802.11ba, and 802.11be, without being limited thereto).

[0161] According to an embodiment, the transceiver 1301 may include various circuit structures used to transmit or receive signals to or from a BS through a wireless channel. The signals may include control information and data. For example, the transceiver 1301 may include a radio frequency (RF) transmitter for up-converting and amplifying the frequency of a transmitted signal and an RF receiver for low-noise-amplifying a received signal and down-converting the frequency thereof. The transceiver 1301 may output a signal received through a wireless channel to the processor 1302 and may transmit, through a wireless channel, a signal output from the processor 1302.

[0162] The processor 1302 may control general operations of the UE 1300 according to embodiments of the disclosure. The processor 1302 may be implemented by one or more integrated circuit (or circuitry) (IC) chips and may execute various data processings. The processor 1302 may include at least one electric circuit, and may execute instructions (or a program, codes, data, etc.) stored in the memory 1303, individually, collectively or in any combination thereof. Further, the processor 1302 may include a single-core processor or multi-core processor, and may include a processor assembly including a plurality of processing circuits (circuitry) according to a specific implementation scheme.

[0163] The processor 1302 may be electrically, operatively, or communicatively coupled to the transceiver 1301 to control the transceiver 1301.

[0164] The processor 1302 may include at least one processor (or processing circuitry), and the at least one processor may perform the following operations individually, collectively or in any combination thereof. For example, the processor 1302 may include a communication processor (CP) configured to control communication operations and an application processor (AP) configured to control execution of an upper layer (for example, an application layer) . In a specific embodiment, at least a part of the processor 1302 may be included in one chip and the other part of the processor 1302 may be included in another chip. Otherwise, at least one processor may be included in another component, for example, the transceiver 1301 or the memory 1303.

[0165] The processor 1302 may perform or control or cause an operation of the UE 1300 for executing at least one or a combination of methods according to embodiments of the disclosure. For example, the processor 1302 may control operations of the UE 1300 for processing a downlink signal received from a BS or generating and transmitting an uplink signal to a BS. To this end, the processor 1302 may execute a computer program, codes, or instructions stored in the memory 1303, so as to control other components of the UE 1300 to enable execution of various operations.

[0166] The memory 1303 corresponds to a hardware storage device capable of temporarily or permanently storing information and may include one or more storage media. For example, the memory 1303 may include a memory assembly including one or more storage media. For example, the one or more storage media may include permanent memory, such as a hard drive, flash memory, or read-only memory (ROM), semipermanent memory, such as random access memory (RAM), cache memory, or a combination thereof.

[0167] The memory 1303 may be electrically, operatively, or communicatively coupled to the processor 1302 and may be accessed by the processor 1302.

[0168] The memory 1303 may store a computer program, codes, or instructions executable by the processor 1302. According to an embodiment, a computer program, codes, or instructions executable by the processor 1302 may be either stored in a single memory device or separated and distributedly stored in two or more memory devices. By executing the instructions stored in the memory 1303, the processor 1302 may perform various functions according to an embodiment of the disclosure.

[0169] According to an embodiment of the disclosure, operations of the UE 1300 may be caused to be performed based on execution of instructions (or a computer program or codes) stored in the memory 1303 by at least one processor (or processing circuitry) configured to execute the same individually, collectively, or in any combination thereof, based on processing circuitry that is not configured to execute instructions, and / or based on components of processing circuitry that is not configured to execute instructions.

[0170] FIG. 14 is a block diagram of a base station (BS) 1400 according to an embodiment of the disclosure. Furthermore, the base station or the network entity of FIG. 14 corresponds to the base station of FIG. 10.

[0171] The BS 1400 may perform wireless communication with at least one user equipment (UE) located within the area of the BS 1400 through a wireless channel.

[0172] Referring to FIG. 14, the BS 1400 may include at least one transceiver (hereinafter, referred to as simply “transceiver”) 1401, at least one processor (hereinafter, referred to as simply “processor”) 1402, and at least one memory (hereinafter, referred to as simply “memory”) 1403. According to at least one or a combination of methods corresponding to the embodiments described in the present disclosure, the transceiver 1401, the processor 1402, and the memory 1403 of the BS 1400 may operate. However, components of the BS 1400 are not limited to the exemplary components illustrated in FIG. 14. In another embodiment, the BS 1400 may further include additional components in addition to the above-mentioned components, or some components may be omitted. Further, in some embodiments, any combination of the transceiver 1401, the processor 1402, or the memory 1403 may be integrated in the form of one component.

[0173] The transceiver 1401 may be a communication circuit or communication circuitry that enables the BS 1400 to perform wireless communication with a node or an entity of a network. For example, the transceiver 1401 may enable the BS 1400 to transmit or receive a signal to or from the UE X00 through cellular communication, or to transmit or receive a signal to or from another network entity through wireless communication. For example, the transceiver 1401 may support various cellular communication technologies including 3rd generation (3G), 4th generation (4G), long term evolution (LTE), 5th generation (5G) NR, 6th generation (6G), and various cellular wireless communication technologies supported by the transceiver (1401) may include all subsequent generations of evolved wireless communications.. According to an embodiment, the transceiver 1401 may include various circuit structures used to transmit or receive signals to or from a UE through a wireless channel. The signals may include control information and data. For example, the transceiver 1401 may include a radio frequency (RF) transmitter for up-converting and amplifying the frequency of a transmitted signal and an RF receiver for low-noise-amplifying a received signal and down-converting the frequency thereof. The transceiver 1401 may output a signal received through a wireless channel to the processor 1402 and may transmit, through a wireless channel, a signal output from the processor 1402.

[0174] Meanwhile, according to an embodiment of the present disclosure, the BS 1400 may perform communication with a node or an entity of a network through wired or wireless communication. For example, the BS 1400 may perform wired or wireless communication with an adjacent BS, or a node or an entity of a core network through a backhaul network. Although not illustrated in FIG. 14, when the BS 1400 performs wired communication, the BS 1400 may further include a separate network interface for wired communication in addition to the transceiver 1401. The network interface may be referred to as network interface circuitry or communication interface circuitry.

[0175] The processor 1402 may control general operations of the BS 1400 according to embodiments of the disclosure. The processor 1402 may be implemented by one or more integrated circuit (or circuitry) (IC) chips and may execute various data processings. The processor 1402 may include at least one electric circuit, and may execute instructions (or a program, codes, data, etc.) stored in the memory 1403, individually, collectively or in any combination thereof. Further, the processor 1402 may include a single-core processor or multi-core processor, and may include a processor assembly including a plurality of processing circuits (circuitry) according to a specific implementation scheme.

[0176] The processor 1402 may be electrically, operatively, or communicatively coupled to the transceiver 1401 to control the transceiver 1401.

[0177] The processor 1402 may include at least one processor (or processing circuitry), and the at least one processor may perform the following operations individually, collectively or in any combination thereof. In a specific embodiment, at least a part of the processor 1402 may be included in one chip and the other part of the processor 1402 may be included in another chip. Otherwise, at least one processor may be included in another component, for example, the transceiver 1401 or the memory 1403.

[0178] The processor 1402 may perform or control or cause an operation of the BS 1400 for executing at least one or a combination of methods according to embodiments of the disclosure. For example, the processor 1402 may control operations of the BS 1400 for generating and transmitting a downlink signal to a UE or processing an uplink signal received from a UE. Otherwise, the BS 1400 may transmit or receive a signal to or from a neighboring BS, transfer a signal received from a UE to an upper node of the network, or transmit a signal transferred from an upper node of the network to a UE. To this end, the processor 1402 may execute a computer program, codes, or instructions stored in the memory 1403, so as to control other components of the BS 1400 to enable execution of various operations.

[0179] The memory 1403 corresponds to a hardware storage device capable of temporarily or permanently storing information and may include one or more storage media. For example, the memory 1403 may include a memory assembly including one or more storage media. For example, the one or more storage media may include permanent memory, such as a hard drive, flash memory, or read-only memory (ROM), semipermanent memory, such as random access memory (RAM), cache memory, or a combination thereof.

[0180] The memory 1403 may be electrically, operatively, or communicatively coupled to the processor 1402 and may be accessed by the processor 1402.

[0181] The memory 1403 may store a computer program, codes, or instructions executable by the processor 1402. According to an embodiment, a computer program, codes, or instructions executable by the processor 1402 may be either stored in a single memory device or separated and distributedly stored in two or more memory devices. By executing the instructions stored in the memory 1403, the processor 1402 may perform various functions according to an embodiment of the disclosure.

[0182] According to an embodiment of the disclosure, operations of the BS 1400 may be caused to be performed based on execution of instructions (or a computer program or codes) stored in the memory 1403 by at least one processor (or processing circuitry) configured to execute the same individually, collectively, or in any combination thereof, based on processing circuitry that is not configured to execute instructions, and / or based on components of processing circuitry that is not configured to execute instructions.

[0183] The UE or the base station may perform various communication procedures related to the control plane or the user plane by cooperating with one or more network entities based on wireless communication. For example, the UE may communicate with network entity such as an Access and Mobility Management Function (AMF) or a Session Management Function (SMF) via the base station, or the base station may perform at least one communication procedure by directly transmitting and receiving signals to / from, or relaying signals between, the network entities.

[0184] The structure of the above-described network entity will be described in more detail with reference to the drawings.

[0185] FIG. 15 is a block diagram of a network entity 1500 according to an embodiment of the disclosure.

[0186] The network entity 1500 may include an entity (apparatus, device, or server, etc.) that performs one or more network functions (NFs) or a part of a network function constituting a core network (e.g., a 5th generation (5G) core (5GC)) in a communication system. In this case, multiple NFs may be implemented within a single network entity, or a single NF may be distributed and implemented across a plurality of network entities. In addition, when an NF is implemented within the network entity, the NF may be implemented in the form of software, and in such a case, a program for operating the NF may be stored in memory of the network entity 1500.

[0187] A single NF may be implemented by one or more instances, which may be deployed on the same network entity or distributed across multiple network entities to operate. The instance may be a software unit that logically executes a specific network function, and may be implemented in a form that is decoupled from physical hardware resources. Further, one or more NFs may be implemented in the form of one network slice to operate to satisfy specifications required by a particular service.

[0188] The NF may include at least one of an access and mobility management function (AMF), a session management function (SMF), a local session management function (L-SMF), a user plane function (UPF), a local user plane function (L-UPF), a policy control function (PCF), a unified data management (UDM), a unified data repository (UDR), a network exposure function (NEF), a network repository function (NRF), an application function (AF), a network slice selection function (NSSF), a network data analytics function (NWDAF), a network slice admission control function (NSACF), an authentication server function (AUSF), or a data network (DN).

[0189] Referring to FIG. 15, the network entity 1500 may include at least one network interface 1501, at least one processor 1502 (hereinafter, “processor”), and at least one memory 1503 (hereinafter, “memory”). As described above, a NF may be implemented in the form of a physical device such as the network entity 1500, or may be virtualized and executed in the form of an instance. When implemented as an instance, the NF need not necessarily include physical components as illustrated in FIG. 15. In such a case, the instance may be logically represented as comprising one or more logical functional elements.

[0190] According to at least one or a combination of methods corresponding to the embodiments described in the present disclosure, the network interface 1501, the processor 1502, and the memory 1503 of the network entity 1500 may operate. However, components of the network entity 1500 are not limited to the exemplary components illustrated in FIG. 15. In another embodiment, the network entity 1500 may further include additional components in addition to the above-mentioned components, or some components may be omitted. Further, in an embodiment, the network interface 1501, the processor 1502, or the memory 1503 may be integrated in the form of one component.

[0191] The network interface 1501 is a collective term for a transmitter part of the network entity 1500 and a receiver part of the network entity 1500, and may be a communication circuit for transmitting or receiving a signal to or from a user equipment (UE), a base station (BS), or another network entity. Here, the communication circuit may include both a communication circuit for wireless communication and a communication circuit for a wired communication. For example, the network interface 1501 may include a circuit, logic, hardware, etc., configured to exchange a control plane message or a user plane message with a UE, a BS, or other core network entities through wireless communication or wired communication. The network interface 1501 may operate using various protocols (e.g., non-access stratum (NAS) protocol). The network interface 1501 may also be referred to, for convenience of description or depending on implementation, as communication circuitry, network interface circuitry, or a communication interface circuitry.

[0192] The processor 1502 may control general operations of the network entity 1500 according to embodiments of the disclosure. The processor 1502 may be implemented by one or more integrated circuit (or circuitry) (IC) chips and may execute various data processings. The processor 1502 may include at least one electric circuit, and may execute instructions (or a program, codes, data, etc.) stored in the memory 1503, individually, collectively or in any combination thereof. Further, the processor 1502 may include a single-core processor or multi-core processor, and may include a processor assembly including a plurality of processing circuits (circuitry) according to a specific implementation scheme. Further, it should be noted that, according to another embodiment, in a case where NF is implemented in the form of an instance, the network function may be not necessarily configured by physical hardware.

[0193] According to an embodiment, the processor 1502 may be electrically, operatively, or communicatively coupled to the network interface 1501 to control the network interface 1501.

[0194] The processor 1502 may include at least one processor (or processing circuitry), and the at least one processor may perform the following operations individually, collectively or in any combination thereof. In a specific embodiment, at least a part of the processor 1502 may be included in one chip and the other part of the processor 1502 may be included in another chip. Otherwise, at least one processor may be included in another component, for example, the network interface 1501 or the memory 1503.

[0195] The processor 1502 may perform or control or cause an operation of the network entity 1500 for executing at least one or a combination of methods according to embodiments of the disclosure. For example, the processor 1502 may control operations of the network entity 1500 for exchanging a control plane message or a user plane message with a UE, a BS, or other core network entities through wireless or wired communication, using various protocols (e.g., NAS protocol). To this end, the processor 1502 may execute a computer program, codes, or instructions stored in the memory 1503, so as to control other components of the network entity 1500 to enable execution of various operations.

[0196] The memory 1503 corresponds to a hardware storage device capable of temporarily or permanently storing information and may include one or more storage media. For example, the memory 1503 may include a memory assembly including one or more storage media. For example, the one or more storage media may include permanent memory, such as a hard drive, flash memory, or read-only memory (ROM), semipermanent memory, such as random access memory (RAM), cache memory, or a combination thereof.

[0197] The memory 1503 may be electrically, operatively, or communicatively coupled to the processor 1502 and may be accessed by the processor 1502.

[0198] The memory 1503 may store a computer program, codes, or instructions executable by the processor 1502. According to an embodiment, a computer program, codes, or instructions executable by the processor 1502 may be either stored in a single memory device or separated and distributedly stored in two or more memory devices. By executing the instructions stored in the memory 1503, the processor 1502 may perform various functions according to an embodiment of the disclosure.

[0199] According to an embodiment of the disclosure, operations of the network entity 1500 may be caused to be performed based on execution of instructions (or a computer program or codes) stored in the memory 1503 by at least one processor (or processing circuitry) configured to execute the same individually, collectively, or in any combination thereof, based on processing circuitry that is not configured to execute instructions, and / or based on components of processing circuitry that is not configured to execute instructions.

[0200] The present disclosure completely solves, or at least mitigates, the prior art problems. It should be understood that some embodiments of the present invention may solve all of the above problems, while another one or more embodiments may not solve all of the above problems at once, but instead solve one or more (but not all) of the above problems. In addition, it will be apparent to one skilled in the art that the disclosed invention may solve other related problems of the prior art that are not explicitly mentioned herein. The main technical advantage of the present invention is to enable the BS to more flexibly allocate time domain resources without negatively affecting the demodulation procedure on the UE side.

[0201] Provided in the first aspect of the present disclosure is the BS-implemented method of communication with one or more UEs, the method comprising: defining possible values of a parameter of time interval of channel estimation performed by one or more UEs using one or more DMRSs for receiving PDSCH; transmitting, using downlink control information (DCI) signaling, to the one or more UEs an indication of a scheduled PDSCH transmission and an indication of a to-be-applied value of said parameter from among the possible values of the parameter; and performing the scheduled PDSCH transmission to the one or more UEs.

[0202] According to the development of the first aspect the value of the channel estimation time interval parameter indicates a group of orthogonal frequency division multiplexing (OFDM) symbols within which UE expects no change by the BS of a precoder applied to the PDSCH transmission.

[0203] According to the development of the first aspect the value of the channel estimation time interval parameter is defined by a total number of OFDM symbols contained in the channel estimation time interval or by a number of OFDM symbols, in which DMRS occurs, within a TTI or a TDRA where the UE expects no change by the BS of a precoder applied to the PDSCH transmission.

[0204] According to the development of the first aspect defining the possible values of the channel estimation time interval parameter includes defining said values with radio resource control (RRC) signaling or medium access control (MAC) signaling.

[0205] According to the development of the first aspect defining the possible values of the channel estimation time interval parameter includes defining said values in a communication standard specification.

[0206] According to the development of the first aspect the indication of the to-be-applied value of said parameter from among the possible values of the parameter is an explicit indication or an implicit indication of the value of said parameter.

[0207] According to the development of the first aspect a specific implicitly indicated value of said parameter is derived from the absence in the DCI of the explicit indication of any value of said parameter.

[0208] According to the development of the first aspect the specific implicitly indicated value of said parameter is the default value of said parameter or another predetermined value.

[0209] According to the development of the first aspect the default value of the parameter indicates for the UE that no change in the precoder applied by the BS is expected over the entire PDSCH transmission time interval.

[0210] According to the development of the first aspect a specific implicitly indicated value of said parameter is derived from the absence in the DCI of the explicit indication of any value of said parameter and / or depending on a format of the signaled DCI.

[0211] According to the development of the first aspect a specific implicitly indicated value of said parameter is derived from the absence in the DCI of the explicit indication of any value of said parameter and based on whether the time domain resources allocated for the PDSCH transmission exceed a threshold value specified in advance in the specification of a communication standard or configured using higher layer signaling, wherein the time domain resources include a number of OFDM symbols or a number of slots in the PDSCH transmission.

[0212] According to the development of the first aspect a specific implicitly indicated value of said parameter is derived from the absence in the DCI of the explicit indication of any value of said parameter and based on whether a number of occurrences of DMRS symbols exceed a threshold value specified in advance in the specification of a communication standard or configured using higher layer signaling.

[0213] According to the development of the first aspect to explicitly indicate the value of said parameter in the DCI one or more bits are allocated.

[0214] According to the development of the first aspect the method further comprises transmitting an explicit indication for the scheduled PDSCH transmission, using DCI signaling, of a precoder change type with power reallocation or a precoder change type with full precoder recalculation.

[0215] Provided in the second aspect of the present disclosure is the BS comprising operatively coupled a transceiving unit, an antenna, a processor, and a readable medium storing processor executable instructions which, when executed by the processor, cause the BS to perform the communication method according to the first aspect of the present disclosure or according to any development of the first aspect of the present disclosure.

[0216] Provided in the third aspect of the present disclosure is the computer-readable medium storing executable instructions that, when executed by a device, cause the device to perform the communication method according to the first aspect of the present disclosure or according to any development of the first aspect of the present disclosure.

[0217] Provided in the fourth aspect of the present disclosure is the UE-implemented method of communication with the BS, the method comprising: receiving, using DCI signaling, an indication of a scheduled transmission of PDSCH and an indication of a to-be-applied value of a channel estimation time interval parameter from among possible values of said parameter; performing channel estimation over one or more DMRS occurrences within the channel estimation time interval of the PDSCH transmission, which is indicated by the value of said parameter; and demodulating the PDSCH transmission based on the obtained channel estimate.

[0218] According to the development of the fourth aspect the value of the channel estimation time interval parameter indicates a group of symbols within which the UE expects no change by the BS of a precoder applied to the PDSCH transmission, wherein the symbols are OFDM symbols.

[0219] According to the development of the fourth aspect the value of the channel estimation time interval parameter is defined by a total number of OFDM symbols contained in the channel estimation time interval or by a number of OFDM symbols, in which DMRS occurs, within TTI or TDRA where the UE expects no change by the BS of a precoder applied to the PDSCH transmission.

[0220] According to the development of the fourth aspect the possible values of the channel estimation time interval parameter are configured with RRC signaling or MAC signaling.

[0221] According to the development of the fourth aspect the possible values of said parameter are specified in advance in a communication standard specification.

[0222] According to the development of the fourth aspect the indication of the to-be-applied value of said parameter from among the possible values of the parameter is an explicit indication or an implicit indication of the value of said parameter.

[0223] According to the development of the fourth aspect a specific implicitly indicated value of said parameter is derived at the UE from the absence in the DCI of the explicit indication of any value of said parameter.

[0224] According to the development of the fourth aspect the specific implicitly indicated value of said parameter is the default value of said parameter or another predetermined value.

[0225] According to the development of the fourth aspect the default value of the parameter indicates for the UE that no change in the precoder applied by the BS is expected over the entire PDSCH transmission time interval.

[0226] According to the development of the fourth aspect a specific implicitly indicated value of said parameter is derived at the UE from the absence in the DCI of the explicit indication of any value of said parameter and / or depending on a format of the signaled DCI.

[0227] According to the development of the fourth aspect a specific implicitly indicated value of said parameter is derived at the UE from the absence in the DCI of the explicit indication of any value of said parameter and based on whether the time domain resources allocated for the PDSCH transmission exceed a threshold value specified in advance in the specification of a communication standard or configured using higher layer signaling, wherein the time domain resources include a number of OFDM symbols or a number of slots in the PDSCH transmission.

[0228] According to the development of the fourth aspect a specific implicitly indicated value of said parameter is derived at the UE from the absence in the DCI of the explicit indication of any value of said parameter and based on whether a number of occurrences of DMRS symbols exceed a threshold value specified in advance in a communication standard specification or configured using higher layer signaling.

[0229] According to the development of the fourth aspect to explicitly indicate the value of said parameter in the DCI one or more bits are allocated.

[0230] According to the development of the fourth aspect the method further comprises receiving an explicit indication for the scheduled PDSCH transmission, using DCI signaling, of a precoder change type with power redistribution or a precoder change type with full precoder recalculation.

[0231] Provided in the fifth aspect of the present disclosure is the user equipment comprising operatively coupled a transceiving unit, an antenna, a processor, and a readable medium storing processor executable instructions which, when executed by the processor, cause the user equipment to perform the communication method according to the fourth aspect of the present disclosure or according to any development of the fourth aspect of the present disclosure.

[0232] Provided in the sixth aspect of the present disclosure is the computer-readable medium storing executable instructions that, when executed by a device, cause the device to perform the communication method according to the fourth aspect of the present disclosure or according to any development of the fourth aspect of the present disclosure.

[0233] Provided in the seventh aspect of the present disclosure is the communication system comprising at least one BS according to the second aspect of the present disclosure or according to any development of the second aspect of the present disclosure and at least one UE according to the fifth aspect of the present disclosure or according to any development of the fifth aspect of the present disclosure, wherein said at least one BS and said at least one UE communicate with each other in the communication system served by said at least one BS.

[0234] Meanwhile, although specific embodiments of the present disclosure have been described in detail, various modifications may be made without departing from the scope of the present disclosure. Therefore, the scope of the present disclosure should not be limited to the described embodiments, but should be defined by the claims and equivalents thereof.

[0235] The present disclosure can be applied in 3GPP compliant communication networks with BSs and UEs that support xMIMO up to 256 digital ports / 4096 antenna elements. The proposed frequency band for using the disclosed disclosure is the upper part of the mid-frequency band (7-13 GHz). The technical solutions according to the present disclosure can be implemented with analog / digital single / multi-beam beamforming and TDD and / or FDD duplex modes. Other applications of the technology disclosed herein will be apparent to those of ordinary skill in the art upon review of this detailed description of the present application.

[0236] At least one aspect of the disclosed technical solution can be implemented by means of an AI model. The function associated with the AI can be performed by a read-only memory, random access memory, and processor(s) (CPU, GPU, NPU). The processor(s) controls the processing of input data in accordance with a predefined operating rule or an AI model stored in read-only memory and random access memory. The predefined operating rule or AI model is provided through training. Here, “provided through training” means that by applying a learning algorithm to a set of training data, a predefined operating rule or AI model with a desired characteristic is created. As the non-limiting example, the AI model may be created that predicts, in real time for subsequent explicit signaling to and dynamic switching at the UE, time domain channel estimation restrictions (i.e., channel estimation time interval parameter values) and / or precoder change type based on parameters associated with a current state of BS 200 and / or UE 400 and / or communication system 500. Such parameters may include, but are not limited to, the current number of transmitting / receiving UEs in the communication system, CSI transmitted from UEs, etc. In this case, a set of optimal channel estimation restrictions in the time domain and / or precoder change types in combination with parameters associated with various states of the BS 200 and / or UE 400 and / or communication system 500 can be used as training data for training such an AI model. The training may be performed within the device itself that uses the AI model according to the embodiment (i.e., online), and / or may be implemented via a separate server / system (i.e., offline).

[0237] The AI model may be a decision tree-based algorithm or may consist of multiple layers of a neural network. Each layer has a plurality of weights and performs the operation of the layer through a calculation based on the result of the calculation in the previous layer and the application of a plurality of weights and other parameter values. Examples of decision tree based algorithms include a random forest, tree ensembles, etc., and examples of neural networks include, among others, Convolutional Neural Network (CNN), Deep Neural Network (DNN), Recurrent Neural Network (RNN), Restricted Boltzmann Machine (RBM), Deep Belief Network (DBN), Bi-directional Network, Bi-directional Recurrent Deep Neural Network (BRDNN), Generative Adversarial Network (GAN), Transformer-based Networks, Deep Q-Network, large language models etc.

[0238] A learning algorithm is a method for learning a predetermined target device or target function based on a corresponding set of training data that causes, enables, controls, or provides output data of the target device or target function. Examples of learning algorithms include, but not limited to, supervised learning, unsupervised learning, semi-supervised learning or reinforcement learning, and so on.

[0239] One skilled in the art may understand that the various illustrative logical blocks (functional blocks or modules) and steps (operations) used in embodiments of the disclosed technical solution may be implemented by electronic hardware, computer software, or a combination of both. Whether the functions are implemented with the use of hardware or software depends on particular applications and requirements to a design of an entire system. A person skilled in the art can use different methods to implement the described functions for each particular application, but it should not be considered that the implementation will go beyond the scope of the embodiments disclosed in the application.

[0240] It should also be noted that the order of the steps of any disclosed method is not strict, since some one or more steps may be rearranged in the actual order of execution and / or combined with another one or more steps, and / or broken down into a larger number of sub-steps.

[0241] Throughout the present application, reference to an element in the singular form does not exclude the presence of a plurality of such elements in the actual implementation of the disclosure, and, conversely, reference to an element in the plural form does not exclude the presence of only one such element in the actual implementation of the disclosure. Any specific value or range of values stated above should not be interpreted in a limiting sense, but instead such specific value or range of values should be considered to represent the midpoint of a specified larger range, up to approximately 50% or more % on either side of the specifically stated value or the boundaries of a specifically stated range.

[0242] Although this disclosure has been shown and described with reference to specific embodiments and examples thereof, those skilled in the art will appreciate that various changes in form and detail may be made without departing from the spirit and scope of this disclosure as defined by the appended claims and their equivalents. In other words, the above detailed description is based on specific examples and possible implementations of the present disclosure, but it should not be interpreted so that only the explicitly disclosed implementations are feasible. It is intended that any modification or substitution that could be made to this disclosure by one of ordinary skill in the art without creative and / or technical contribution shall be within the scope of protection (with equivalents considered) provided by the following claims.

Claims

1.A method performed by a base station (BS) in a wireless communication system, the method comprising:defining possible values of a parameter of time interval of channel estimation performed by at least one user equipment(UE) using one or more demodulation reference signal (DMRS) for receiving a physical downlink shared channel (PDSCH);using downlink control information (DCI) signaling, transmitting, to the at least one UE, an indication of a scheduled PDSCH transmission and an indication of a to-be-applied value of said parameter from among the possible values of the parameter; andperforming the scheduled PDSCH transmission to the at least one UE.2.The method of claim 1, wherein the value of the channel estimation time interval parameter indicates a group of orthogonal frequency division multiplexing (OFDM) symbols within which UE expects no change by the BS of a precoder applied to the PDSCH transmission.3.The method of claim 1, wherein the value of the channel estimation time interval parameter is defined by a total number of OFDM symbols contained in the channel estimation time interval or by a number of OFDM symbols, in which DMRS occurs, within a transmission time interval (TTI) or a time domain resource allocation (TDRA) where the UE expects no change by the BS of a precoder applied to the PDSCH transmission.4.The method of claim 1, wherein the defining the possible values of the channel estimation time interval parameter includes defining the values with radio resource control (RRC) signaling or medium access control (MAC) signaling.5.A base station (BS) in a wireless communication system, comprising:at least one transceiver;at least one processor communicatively coupled to the at least one transceiver; andat least one memory, communicatively coupled to the at least one processor, storing instructions executable by the at least one processor individually or in any combination to cause the BS to:define possible values of a parameter of time interval of channel estimation performed by at least one user equipment(UE) using one or more demodulation reference signal (DMRS) for receiving a physical downlink shared channel (PDSCH);using downlink control information (DCI) signaling, transmit, to the at least one UE, an indication of a scheduled PDSCH transmission and an indication of a to-be-applied value of the parameter from among the possible values of the parameter; andperform the scheduled PDSCH transmission to the at least one UE.6.The BS of claim 5, wherein the value of the channel estimation time interval parameter indicates a group of orthogonal frequency division multiplexing (OFDM) symbols within which UE expects no change by the BS of a precoder applied to the PDSCH transmission.7.The BS of claim 5, wherein the value of the channel estimation time interval parameter is defined by a total number of OFDM symbols contained in the channel estimation time interval or by a number of OFDM symbols, in which DMRS occurs, within a transmission time interval (TTI) or a time domain resource allocation (TDRA) where the UE expects no change by the BS of a precoder applied to the PDSCH transmission.8.The BS of claim 5, wherein the instructions further cause the BS to define the values with radio resource control (RRC) signaling or medium access control (MAC) signaling.9.A method performed by a user equipment (UE) in a wireless communication system, the method comprising:receiving, from a base station (BS), using downlink control information (DCI) signaling, an indication of a scheduled transmission of a physical downlink shared channel (PDSCH) and an indication of a to-be-applied value of a channel estimation time interval parameter from among possible values of the parameter;performing channel estimation with one or more demodulation reference signal (DMRS) occurrences within the channel estimation time interval of the PDSCH transmission, which is indicated by the value of the parameter; anddemodulating the PDSCH transmission based on the obtained channel estimate.10.The method of claim 9, wherein the value of the channel estimation time interval parameter indicates a group of symbols within which the UE expects no change by the BS of a precoder applied to the PDSCH transmission, wherein the symbols are orthogonal frequency division multiplexing (OFDM) symbols.11.The method of claim 9, wherein the value of the channel estimation time interval parameter is defined by a total number of OFDM symbols contained in the channel estimation time interval or by a number of OFDM symbols, in which DMRS occurs, within a transmission time interval (TTI) or a time domain resource allocation (TDRA) where the UE expects no change by the BS of a precoder applied to the PDSCH transmission.12.The method of claim 9, wherein the possible values of the channel estimation time interval parameter are configured with radio resource control (RRC) signaling or medium access control (MAC) signaling.13.A user equipment (UE) in a wireless communication system, comprising:at least one transceiver;at least one processor communicatively coupled to the at least one transceiver; andat least one memory, communicatively coupled to the at least one processor, storing instructions executable by the at least one processor individually or in any combination to cause the UE to:receive, from a base station (BS), using downlink control information (DCI) signaling, an indication of a scheduled transmission of a physical downlink shared channel (PDSCH) and an indication of a to-be-applied value of a channel estimation time interval parameter from among possible values of the parameter;perform channel estimation with one or more demodulation reference signal (DMRS) occurrences within the channel estimation time interval of the PDSCH transmission, which is indicated by the value of the parameter; anddemodulate the PDSCH transmission based on the obtained channel estimate.14.The UE of claim 13, wherein the value of the channel estimation time interval parameter indicates a group of symbols within which the UE expects no change by the BS of a precoder applied to the PDSCH transmission, wherein the symbols are orthogonal frequency division multiplexing (OFDM) symbols.15.The UE of claim 13, wherein the value of the channel estimation time interval parameter is defined by a total number of OFDM symbols contained in the channel estimation time interval or by a number of OFDM symbols, in which DMRS occurs, within a transmission time interval (TTI) or a time domain resource allocation (TDRA) where the UE expects no change by the BS of a precoder applied to the PDSCH transmission.

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