Method and apparatus for indication of port transformation matrices for compressed channel measurement in wireless communication systems

Abstract

A method performed by a user equipment (UE) in a wireless communication system is provided. The method includes receiving configuration information on a channel state information (CSI) report, receiving channel state information reference signal (CSI-RS) on at least one CSI-RS resource with M ports based on the configuration information, calculating a CSI parameter for N ports based on the CSI-RS, and transmitting the CSI report including the CSI parameter for N ports, wherein M and N are integers and M < N.

Description

[Rectified under Rule 91, 23.10.2025]METHOD AND APPARATUS FOR INDICATION OF PORT TRANSFORMATION MATRICES FOR COMPRESSED CHANNEL MEASUREMENT IN WIRELESS COMMUNICATION SYSTEMS

[0001] The disclosure relates to the field of 5th generation (5G) and beyond 5G communication networks, and more particularly, to channel state information (CSI) measurement and feedback in multiple-input multiple-output (MIMO) system.

[0002] 5G mobile communication technologies define broad frequency bands such that high transmission rates and new services are possible, and can be implemented not only in “Sub 6GHz” bands such as 3.5 GHz, but also in “Above 6 GHz” bands referred to as mmWave including 28 GHz and 39 GHz. In addition, it has been considered to implement 6th generation (6G) mobile communication technologies (referred to as Beyond 5G systems) in terahertz bands (for example, 95 GHz to 3 THz bands) in order to accomplish transmission rates fifty times faster than 5G mobile communication technologies and ultra-low latencies one-tenth of 5G mobile communication technologies.

[0003] At the beginning of the development of 5G mobile communication technologies, in order to support services and to satisfy performance requirements in connection with enhanced mobile broadband (eMBB), ultra reliable low latency communications (URLLC), and massive machine-type communications (mMTC), there has been ongoing standardization regarding beamforming and massive multi input multi output (MIMO) for mitigating radio-wave path loss and increasing radio-wave transmission distances in mmWave, supporting numerologies (for example, operating multiple subcarrier spacings) for efficiently utilizing mmWave resources and dynamic operation of slot formats, initial access technologies for supporting multi-beam transmission and broadbands, definition and operation of bandwidth part (BWP), new channel coding methods such as a low density parity check (LDPC) code for large amount of data transmission and a polar code for highly reliable transmission of control information, L2 pre-processing, and network slicing for providing a dedicated network specialized to a specific service.

[0004] Currently, there are ongoing discussions regarding improvement and performance enhancement of initial 5G mobile communication technologies in view of services to be supported by 5G mobile communication technologies, and there has been physical layer standardization regarding technologies such as vehicle-to-everything (V2X) for aiding driving determination by autonomous vehicles based on information regarding positions and states of vehicles transmitted by the vehicles and for enhancing user convenience, new radio unlicensed (NR-U) aimed at system operations conforming to various regulation-related requirements in unlicensed bands, NR user equipment (UE) power saving, non-terrestrial network (NTN) which is UE-satellite direct communication for providing coverage in an area in which communication with terrestrial networks is unavailable, and positioning.

[0005] Moreover, there has been ongoing standardization in air interface architecture / protocol regarding technologies such as industrial internet of things (IIoT) for supporting new services through interworking and convergence with other industries, integrated access and backhaul (IAB) for providing a node for network service area expansion by supporting a wireless backhaul link and an access link in an integrated manner, mobility enhancement including conditional handover and dual active protocol stack (DAPS) handover, and two-step random access for simplifying random access procedures (2-step RACH for NR). There also has been ongoing standardization in system architecture / service regarding a 5G baseline architecture (for example, service based architecture or service based interface) for combining Network Functions Virtualization (NFV) and Software-Defined Networking (SDN) technologies, and Mobile Edge Computing (MEC) for receiving services based on UE positions.

[0006] As 5G mobile communication systems are commercialized, connected devices that have been exponentially increasing will be connected to communication networks, and it is accordingly expected that enhanced functions and performances of 5G mobile communication systems and integrated operations of connected devices will be necessary. To this end, new research is scheduled in connection with eXtended Reality (XR) for efficiently supporting Augmented Reality (AR), Virtual Reality (VR), Mixed Reality (MR) and the like, 5G performance improvement and complexity reduction by utilizing Artificial Intelligence (AI) and Machine Learning (ML), AI service support, metaverse service support, and drone communication.

[0007] Furthermore, such development of 5G mobile communication systems will serve as a basis for developing not only new waveforms for providing coverage in terahertz bands of 6G mobile communication technologies, multi-antenna transmission technologies such as Full Dimensional MIMO (FD-MIMO), array antennas and large-scale antennas, metamaterial-based lenses and antennas for improving coverage of terahertz band signals, high-dimensional space multiplexing technology using Orbital Angular Momentum (OAM), and Reconfigurable Intelligent Surface (RIS), but also full-duplex technology for increasing frequency efficiency of 6G mobile communication technologies and improving system networks, AI-based communication technology for implementing system optimization by utilizing satellites and AI from the design stage and internalizing end-to-end AI support functions, and next-generation distributed computing technology for implementing services at levels of complexity exceeding the limit of UE operation capability by utilizing ultra-high-performance communication and computing resources.

[0008] The following documents may be referenced to understand the disclosure.

[0009] [1] RP-193133, New WID: Further enhancements on MIMO for NR, Samsung,

[0010] [2] 3GPP TS 38.213, V15.12.0(2020-12): "NR; Physical layer procedures for control (Release 15)",

[0011] [3] 3GPP TS 38.214, V15.11.0 (2020-09): "NR; Physical layer procedures for data (Release 15)",

[0012] [4] 3GPP TS 38.213, V16.4.0 (2020-12): "NR; Physical layer procedures for control (Release 16)",

[0013] [5] 3GPP TS 38.214, V16.4.0 (2020-12): "NR; Physical layer procedures for data (Release 16)",

[0014] [6] 3GPP TS 38.321, V16.3.0 (2020-12): "NR; Medium Access Control (MAC) protocol specification (Release 16)",

[0015] [7] 3GPP TS 38.331, V16.3.1 (2021-01): "NR; Radio Resource Control (RRC) protocol specification”,

[0016] [8] 3GPP TS 38.211, V16.4.0 (2020-12): "NR; Physical channels and modulation”,

[0017] [9] 3GPP TS 38.212, V16.4.0 (2020-12): "NR; Multiplexing and channel coding”,

[0018]

[0010] 3GPP TS 38.215, V16.4.0 (2020-12): "NR; Physical layer measurements”.

[0019] The disclosure provides methods and apparatus for CSI reporting in communication networks, wherein the communication network is at least one of the 5G standalone network, a 5G non-standalone (NAS) network or 6G network.

[0020] Specifically, the disclosure provides methods and systems to configure a UE with a CSI measurement for M ports and a CSI report including the precoding information for N ports, where M<N signifying compressed measurement.

[0021] In accordance with an aspect of the disclosure, a method performed by a user equipment (UE) in a wireless communication system is provided. The method includes receiving configuration information on a channel state information (CSI) report, receiving channel state information reference signal (CSI-RS) on at least one CSI-RS resource with M ports based on the configuration information, calculating a CSI parameter for N ports based on the CSI-RS, and transmitting the CSI report including the CSI parameter for N ports, wherein M and N are integers and M < N.

[0022] In accordance with another aspect of the disclosure, a method performed by a base station (BS) in a wireless communication system is provided. The method includes transmitting, to a user equipment (UE) configuration information on a channel state information (CSI) report, transmitting, to the UE, channel state information reference signal (CSI-RS) on at least one CSI-RS resource with M ports based on the configuration information, and receiving, from the UE, the CSI report including a CSI parameter for N ports, wherein the CSI parameter for N ports is derived based on the CSI-RS, and wherein M and N are integers and M < N.

[0023] In accordance with another aspect of the disclosure, a user equipment (UE) in a wireless communication system is provided. The UE includes at least one transceiver and at least one processor coupled with the at least one transceiver, where the at least one processor is configured to receive configuration information on a channel state information (CSI) report, receive channel state information reference signal (CSI-RS) on at least one CSI-RS resource with M ports based on the configuration information, calculate a CSI parameter for N ports based on the CSI-RS, and transmit the CSI report including the CSI parameter for N ports, wherein M and N are integers and M < N.

[0024] In accordance with another aspect of the disclosure, a base station (BS) in a wireless communication system is provided. The BS includes at least one transceiver and at least one processor coupled with the at least one transceiver, where the at least one processor is configured to transmit, to a user equipment (UE) configuration information on a channel state information (CSI) report, transmit, to the UE, channel state information reference signal (CSI-RS) on at least one CSI-RS resource with M ports based on the configuration information, and receive, from the UE, the CSI report including a CSI parameter for N ports, wherein the CSI parameter for N ports is derived based on the CSI-RS, and wherein M and N are integers and M < N.

[0025] According to an embodiment of the disclosure, efficiency of CSI reporting can be improved.

[0026] Further, according to an embodiment of the disclosure, overhead of CSI-RS resource can be reduced.

[0027] Further, according to an embodiment of the disclosure, CSI reporting for multiple antenna ports can be supported through compressed measurements.

[0028] Embodiments herein are illustrated in the accompanying drawings, throughout which like reference letters indicate corresponding parts in the various figures. The embodiments herein will be better understood from the following description with reference to the drawings, in which:

[0029] FIG. 1 illustrates an example wireless network according to an embodiment of the disclosure;

[0030] FIG. 2A illustrates an example wireless transmit path according to an embodiment of the disclosure;

[0031] FIG. 2B illustrates an example wireless receive path according to an embodiment of the disclosure;

[0032] FIG. 3A illustrates an example UE according to an embodiment of the disclosure;

[0033] FIG. 3B illustrates an example gNB according to an embodiment of the disclosure;

[0034] FIG. 4 illustrates an exemplary cross-polarized MIMO antenna system;

[0035] FIG. 5 illustrates an exemplary layout for channel state information reference signal (CSI-RS) resource mapping in an orthogonal frequency division multiplexing (OFDM) time-frequency grid;

[0036] FIG. 6 illustrates an example of precoder construction in Type II CSI;

[0037] FIG. 7A illustrates exemplary reported precoding matrices in subband granularity;

[0038] FIG. 7B illustrates an exemplary precoding matrix construction for enhanced Type II CSI;

[0039] FIG. 8 illustrates an auto encoder based CSI feedback;

[0040] FIG. 9 depicts an example for an auto encoder based CSI feedback according to an embodiment of the disclosure;

[0041] FIG. 10 illustrates an exemplary CSI-RS port mapping for 128 ports;

[0042] FIG. 11 illustrates a procedure for compressed CSI measurement and reporting according to an embodiment of the disclosure;

[0043] FIG. 12 illustrates an exemplary port transformation operation of a network according to an embodiment of the disclosure;

[0044] FIG. 13 illustrates an exemplary method for a learning based determination of the port transformation matrices according to an embodiment of the disclosure;

[0045] FIG. 14 illustrates an exemplary procedure for the data collection and inference pertinent to UE-side trained AI / ML model according to an embodiment of the disclosure;

[0046] FIG. 15 illustrates an exemplary configuration with one-to-many mapping between the CMRs for full channel measurement and partial port measurements according to an embodiment of the disclosure; and

[0047] FIG. 16 illustrates an exemplary procedure for data collection related capability and preference indications between the UE and the network, according to an embodiment of the disclosure.

[0048] Hereinafter, embodiments of the disclosure will be described in detail with reference to the accompanying drawings.

[0049] 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.

[0050] 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.

[0051] 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.

[0052] 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).

[0053] 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.

[0054] 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.

[0055] 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.

[0056] 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.

[0057] 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.

[0058] 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.

[0059] 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.

[0060] 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.

[0061] 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.

[0062] 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.

[0063] 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.

[0064] 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.

[0065] 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.

[0066] 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.

[0067] 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.

[0068] Furthermore, throughout the 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.

[0069] 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.

[0070] 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.

[0071] 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.

[0072] 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.

[0073] 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.

[0074] 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.

[0075] 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.

[0076] 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.

[0077] 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.

[0078] 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.

[0079] 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.

[0080] 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.

[0081] 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.

[0082] 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.

[0083] 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.

[0084] 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.

[0085] 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

[0086] 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."

[0087] 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.

[0088] 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.

[0089] 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.

[0090] Hereinafter, the operational principle of the present disclosure will be described in detail with reference to the accompanying drawings.

[0091] Wireless communication has been one of the most successful innovations in modern history. Recently, the number of subscribers to wireless communication services exceeded five billion and continues to grow quickly. The demand of wireless data traffic is rapidly increasing due to the growing popularity among consumers and businesses of smart phones and other mobile data devices, such as tablets, “note pad” computers, net books, eBook readers, and machine type of devices. In order to meet the high growth in mobile data traffic and support new applications and deployments, improvements in radio interface efficiency and coverage is of paramount importance.

[0092] To meet the demand for wireless data traffic having increased since deployment of 4G communication systems, and to enable various vertical applications, 5G communication systems have been developed and are currently being deployed.

[0093] The 5G communication system is considered to be implemented to include higher frequency (mmWave) bands, such as 28 GHz or 60 GHz bands or, in general, above 6 GHz bands, so as to accomplish higher data rates, or in lower frequency bands, such as below 6 GHz, to enable robust coverage and mobility support. Aspects of the present disclosure may be applied to deployment of 5G communication systems, 6G or even later releases which may use THz bands. 　To decrease propagation loss of the radio waves and increase the transmission distance, the beamforming, massive multiple-input multiple-output (MIMO), Full Dimensional MIMO (FD-MIMO), array antenna, an analog beam forming, large-scale antenna techniques are discussed in 5G communication systems.

[0094] In addition, in 5G communication systems, development for system network improvement is under way based on advanced small cells, cloud Radio Access Networks (RANs), ultra-dense networks, device-to-device (D2D) communication, wireless backhaul, moving network, cooperative communication, Coordinated Multi-Points (CoMP), reception-end interference cancellation and the like.

[0095] FIG. 1 illustrates an example wireless network 100 according to an embodiment of the disclosure.

[0096] The embodiment of the wireless network 100 shown in FIG. 1 is for illustration only. Other embodiments of the wireless network 100 can be used without departing from the scope of the disclosure.

[0097] Referring to FIG. 1, the wireless network 100 includes an gNodeB (gNB) 101, an gNB 102, and an gNB 103. The gNB 101 communicates with the gNB 102 and the gNB 103. The gNB 101 also communicates with at least one Internet Protocol (IP) network 130, such as the Internet, a proprietary IP network, or other data network.

[0098] Depending on the network type, the term 'gNB' can refer to any component (or collection of components) configured to provide remote terminals with wireless access to a network, such as base transceiver station, a base station (BS), a radio base station, transmit point (TP), transmit-receive point (TRP), a ground gateway, an airborne gNB, a satellite system, mobile base station, a macrocell, a femtocell, a WiFi access point (AP) and the like. Also, depending on the network type, other well-known terms may be used instead of “user equipment” or “UE,” such as “mobile station,” “subscriber station,” “remote terminal,” “wireless terminal,” or “user device.” For the sake of convenience, the terms “user equipment” and “UE” are used in this patent document to refer to equipment that wirelessly accesses a gNB. The UE could be a mobile device or a stationary device. For example, UE could be a mobile telephone, smartphone, monitoring device, alarm device, fleet management device, asset tracking device, automobile, desktop computer, entertainment device, infotainment device, vending machine, electricity meter, water meter, gas meter, security device, sensor device, appliance etc.

[0099] The gNB 102 provides wireless broadband access to the network 130 for a first plurality of user equipments (UEs) within a coverage area 120 of the gNB 102. The first plurality of UEs includes a UE 111, which may be located in a small business (SB); a UE 112, which may be located in an enterprise (E); a UE 113, which may be located in a WiFi hotspot (HS); a UE 114, which may be located in a first residence (R); a UE 115, which may be located in a second residence (R); and a UE 116, which may be a mobile device (M) like a cell phone, a wireless laptop, a wireless PDA, or the like. The gNB 103 provides wireless broadband access to the network 130 for a second plurality of UEs within a coverage area 125 of the gNB 103. The second plurality of UEs includes the UE 115 and the UE 116. In some embodiments, one or more of the gNBs 101-103 may communicate with each other and with the UEs 111-116 using 5G, long-term evolution (LTE), LTE-A, WiMAX, or other advanced wireless communication techniques.

[0100] Dotted lines show the approximate extents of the coverage areas 120 and 125, which are shown as approximately circular for the purposes of illustration and explanation only. It should be clearly understood that the coverage areas associated with gNBs, such as the coverage areas 120 and 125, may have other shapes, including irregular shapes, depending upon the configuration of the gNBs and variations in the radio environment associated with natural and man-made obstructions.

[0101] As described in more detail below, one or more of gNB　101, gNB　102 and gNB　103 include two-dimensional (2D) antenna arrays as described in embodiments of the present disclosure. In some embodiments, one or more of gNB　101, gNB　102 and gNB　103 support the codebook design and structure for systems having 2D antenna arrays.

[0102] Although FIG. 1 illustrates one example of a wireless network 100, various changes may be made to FIG. 1. For example, the wireless network 100 can include any number of gNBs and any number of UEs in any suitable arrangement. Also, the gNB 101 can communicate directly with any number of UEs and provide those UEs with wireless broadband access to the network 130. Similarly, each gNB 102-103 can communicate directly with the network 130 and provide UEs with direct wireless broadband access to the network 130. Further, the gNB 101, 102, and / or 103 can provide access to other or additional external networks, such as external telephone networks or other types of data networks.

[0103] FIGS. 2A and 2B illustrate example wireless transmit and receive paths according to an embodiment of the disclosure.

[0104] In the following description, a transmit path 200 may be described as being implemented in an gNB (such as gNB 102), while a receive path 250 may be described as being implemented in a UE (such as UE 116). However, it will be understood that the receive path 250 can be implemented in an gNB and that the transmit path 200 can be implemented in a UE. In some embodiments, the receive path 250 is configured to support the codebook design and structure for systems having 2D antenna arrays as described in embodiments of the present disclosure.

[0105] The transmit path 200 includes a channel coding and modulation block 205, a serial-to-parallel (S-to-P) block 210, a size N Inverse Fast Fourier Transform (IFFT) block 215, a parallel-to-serial (P-to-S) block 220, an add cyclic prefix (CP) block 225, and an up-converter (UC) 230. The receive path 250 includes a down-converter (DC) 255, a remove cyclic prefix block 260, a serial-to-parallel (S-to-P) block 265, a size N Fast Fourier Transform (FFT) block 270, a parallel-to-serial (P-to-S) block 275, and a channel decoding and demodulation block 280.

[0106] In the transmit path 200, the channel coding and modulation block 205 receives a set of information bits, applies coding (such as a low-density parity check (LDPC) coding), and modulates the input bits (such as with Quadrature Phase Shift Keying (QPSK) or Quadrature Amplitude Modulation (QAM)) to generate a sequence of frequency-domain modulation symbols. The serial-to-parallel block 210 converts (such as de-multiplexes) the serial modulated symbols to parallel data in order to generate N parallel symbol streams, where N is the IFFT / FFT size used in the gNB 102 and the UE 116. The size N IFFT block 215 performs an IFFT operation on the N parallel symbol streams to generate time-domain output signals. The parallel-to-serial block 220 converts (such as multiplexes) the parallel time-domain output symbols from the size N IFFT block 215 in order to generate a serial time-domain signal. The add cyclic prefix block 225 inserts a cyclic prefix to the time-domain signal. The up-converter 230 modulates (such as up-converts) the output of the add cyclic prefix block 225 to an RF frequency for transmission via a wireless channel. The signal may also be filtered at baseband before conversion to the RF frequency.

[0107] A transmitted RF signal from the gNB 102 arrives at the UE 116 after passing through the wireless channel, and reverse operations to those at the gNB 102 are performed at the UE 116. The down-converter 255 down-converts the received signal to a baseband frequency, and the remove cyclic prefix block 260 removes the cyclic prefix to generate a serial time-domain baseband signal. The serial-to-parallel block 265 converts the time-domain baseband signal to parallel time domain signals. The size N FFT block 270 performs an FFT algorithm to generate N parallel frequency-domain signals. The parallel-to-serial block 275 converts the parallel frequency-domain signals to a sequence of modulated data symbols. The channel decoding and demodulation block 280 demodulates and decodes the modulated symbols to recover the original input data stream.

[0108] Each of the gNBs 101-103 may implement a transmit path 200 that is analogous to transmitting in the downlink (DL) to UEs 111-116 and may implement a receive path 250 that is analogous to receiving in the uplink (UL) from UEs 111-116. Similarly, each of UEs 111-116 may implement a transmit path 200 for transmitting in the uplink to gNBs 101-103 and may implement a receive path 250 for receiving in the downlink from gNBs 101-103.

[0109] Each of the components in FIGS. 2A and 2B can be implemented using only hardware or using a combination of hardware and software / firmware. As a particular example, at least some of the components in FIGS. 2A and 2B may be implemented in software, while other components may be implemented by configurable hardware or a mixture of software and configurable hardware. For instance, the FFT block 270 and the IFFT block 215 may be implemented as configurable software algorithms, where the value of size N may be modified according to the implementation.

[0110] Furthermore, although described as using FFT and IFFT, this is by way of illustration only and should not be construed to limit the scope of the disclosure. Other types of transforms, such as Discrete Fourier Transform (DFT) and Inverse Discrete Fourier Transform (IDFT) functions, can be used. It will be appreciated that the value of the variable N may be any integer number (such as 1, 2, 3, 4, or the like) for DFT and IDFT functions, while the value of the variable N may be any integer number that is a power of two (such as 1, 2, 4, 8, 16, or the like) for FFT and IFFT functions.

[0111] Although FIGS. 2A and 2B illustrate examples of wireless transmit and receive paths, various changes may be made to FIGS. 2A and 2B. For example, various components in FIGS. 2A and 2B can be combined, further subdivided, or omitted and additional components can be added according to particular needs. Also, FIGS. 2A and 2B are meant to illustrate examples of the types of transmit and receive paths that can be used in a wireless network. Any other suitable architectures can be used to support wireless communications in a wireless network.

[0112] FIG. 3A illustrates an example UE 116 according to an embodiment of the disclosure.

[0113] The embodiment of the UE 116 illustrated in FIG. 3A is for illustration only, and the UEs 111-115 of FIG. 1 can have the same or similar configuration. However, UEs come in a wide variety of configurations, and FIG. 3A does not limit the scope of the disclosure to any particular implementation of a UE.

[0114] Referring to the FIG. 3A, the UE　116 includes an antenna 305, a radio frequency (RF) transceiver 310, transmit (TX) processing circuitry 315, a microphone 320, and receive (RX) processing circuitry 325. The UE　116 also includes a speaker 330, a main processor 340, an input / output (I / O) interface (IF) 345, a keypad 350, a display 355, and a memory 360. The memory 360 includes a basic operating system (OS) program 361 and one or more applications 362.

[0115] The RF transceiver 310 receives, from the antenna 305, an incoming RF signal transmitted by a gNB of the network 100. The RF transceiver 310 down-converts the incoming RF signal to generate an intermediate frequency (IF) or baseband signal. The IF or baseband signal is sent to the RX processing circuitry 325, which generates a processed baseband signal by filtering, decoding, and / or digitizing the baseband or IF signal. The RX processing circuitry 325 transmits the processed baseband signal to the speaker 330 (such as for voice data) or to the main processor 340 for further processing (such as for web browsing data).

[0116] The TX processing circuitry 315 receives analog or digital voice data from the microphone 320 or other outgoing baseband data (such as web data, e-mail, or interactive video game data) from the main processor 340. The TX processing circuitry 315 encodes, multiplexes, and / or digitizes the outgoing baseband data to generate a processed baseband or IF signal. The RF transceiver 310 receives the outgoing processed baseband or IF signal from the TX processing circuitry 315 and up-converts the baseband or IF signal to an RF signal that is transmitted via the antenna 305.

[0117] The main processor 340 can include one or more processors or other processing devices and execute the basic OS program 361 stored in the memory 360 in order to control the overall operation of the UE 116. For example, the main processor 340 can control the reception of forward channel signals and the transmission of reverse channel signals by the RF transceiver 310, the RX processing circuitry 325, and the TX processing circuitry 315 in accordance with well-known principles. In some embodiments, the main processor 340 includes at least one microprocessor or microcontroller.

[0118] The main processor 340 is also capable of executing other processes and programs resident in the memory 360, such as operations for channel quality measurement and reporting for systems having 2D antenna arrays as described in embodiments of the present disclosure as described in embodiments of the present disclosure. The main processor 340 can move data into or out of the memory 360 as required by an executing process. In some embodiments, the main processor 340 is configured to execute the applications 362 based on the OS program 361 or in response to signals received from gNBs or an operator. The main processor 340 is also coupled to the I / O interface 345, which provides the UE 116 with the ability to connect to other devices such as laptop computers and handheld computers. The I / O interface 345 is the communication path between these accessories and the main controller 340.

[0119] The main processor 340 is also coupled to the keypad 350 and the display unit 355. The operator of the UE 116 can use the keypad 350 to enter data into the UE 116. The display 355 may be a liquid crystal display or other display capable of rendering text and / or at least limited graphics, such as from web sites. The memory 360 is coupled to the main processor 340. Part of the memory 360 can include a random access memory (RAM), and another part of the memory 360 can include a Flash memory or other read-only memory (ROM).

[0120] Although FIG. 3A illustrates one example of UE 116, various changes may be made to FIG. 3A. For example, various components in FIG. 3A can be combined, further subdivided, or omitted and additional components can be added according to particular needs. As a particular example, the main processor 340 can be divided into multiple processors, such as one or more central processing units (CPUs) and one or more graphics processing units (GPUs). Also, while FIG. 3A illustrates the UE 116 configured as a mobile telephone or smartphone, UEs can be configured to operate as other types of mobile or stationary devices.

[0121] FIG. 3B illustrates an example gNB 102 according to an embodiment of the disclosure.

[0122] The embodiment of the gNB 102 shown in FIG. 3B is for illustration only, and other gNBs of FIG. 1 can have the same or similar configuration. However, gNBs come in a wide variety of configurations, and FIG. 3B does not limit the scope of the disclosure to any particular implementation of an gNB. It is noted that gNB　101 and gNB　103 can include the same or similar structure as gNB　102.

[0123] Referring to FIG. 3B, the gNB 102 includes multiple antennas 370a-370n, multiple RF transceivers 372a-372n, transmit (TX) processing circuitry 374, and receive (RX) processing circuitry 376. In certain embodiments, one or more of the multiple antennas 370a-370n include 2D antenna arrays. The gNB 102 also includes a controller / processor 378, a memory 380, and a backhaul or network interface 382.

[0124] The RF transceivers 372a-372n receive, from the antennas 370a-370n, incoming RF signals, such as signals transmitted by UEs or other gNBs. The RF transceivers 372a-372n down-convert the incoming RF signals to generate IF or baseband signals. The IF or baseband signals are sent to the RX processing circuitry 376, which generates processed baseband signals by filtering, decoding, and / or digitizing the baseband or IF signals. The RX processing circuitry 376 transmits the processed baseband signals to the controller / processor 378 for further processing.

[0125] The TX processing circuitry 374 receives analog or digital data (such as voice data, web data, e-mail, or interactive video game data) from the controller / processor 378. The TX processing circuitry 374 encodes, multiplexes, and / or digitizes the outgoing baseband data to generate processed baseband or IF signals. The RF transceivers 372a-372n receive the outgoing processed baseband or IF signals from the TX processing circuitry 374 and up-converts the baseband or IF signals to RF signals that are transmitted via the antennas 370a-370n.

[0126] The controller / processor 378 can include one or more processors or other processing devices that control the overall operation of the gNB 102. For example, the controller / processor 378 can control the reception of forward channel signals and the transmission of reverse channel signals by the RF transceivers 372a-372n, the RX processing circuitry 376, and the TX processing circuitry 374 in accordance with well-known principles. The controller / processor 378 can support additional functions as well, such as more advanced wireless communication functions. For instance, the controller / processor 378 can perform the blind interference sensing (BIS) process, such as performed by a BIS algorithm, and decodes the received signal subtracted by the interfering signals. Any of a wide variety of other functions can be supported in the gNB 102 by the controller / processor 378. In some embodiments, the controller / processor 378 includes at least one microprocessor or microcontroller.

[0127] The controller / processor 378 is also capable of executing programs and other processes resident in the memory 380, such as a basic OS. The controller / processor 378 is also capable of supporting channel quality measurement and reporting for systems having 2D antenna arrays as described in embodiments of the present disclosure. In some embodiments, the controller / processor 378 supports communications between entities, such as web RTC. The controller / processor 378 can move data into or out of the memory 380 as required by an executing process.

[0128] The controller / processor 378 is also coupled to the backhaul or network interface 382. The backhaul or network interface 382 allows the gNB 102 to communicate with other devices or systems over a backhaul connection or over a network. The interface 382 can support communications over any suitable wired or wireless connection(s). For example, when the gNB 102 is implemented as part of a cellular communication system (such as one supporting 5G, LTE, or LTE-A), the interface 382 can allow the gNB 102 to communicate with other gNBs over a wired or wireless backhaul connection. When the gNB 102 is implemented as an access point, the interface 382 can allow the gNB 102 to communicate over a wired or wireless local area network or over a wired or wireless connection to a larger network (such as the Internet). The interface 382 includes any suitable structure supporting communications over a wired or wireless connection, such as an Ethernet or RF transceiver.

[0129] The memory 380 is coupled to the controller / processor 378. Part of the memory 380 can include a RAM, and another part of the memory 380 can include a Flash memory or other ROM. In certain embodiments, a plurality of instructions, such as a BIS algorithm is stored in memory. The plurality of instructions are configured to cause the controller / processor 378 to perform the BIS process and to decode a received signal after subtracting out at least one interfering signal determined by the BIS algorithm.

[0130] As described in more detail below, the transmit and receive paths of the gNB 102 (implemented using the RF transceivers 372a-372n, TX processing circuitry 374, and / or RX processing circuitry 376) support communication with aggregation of frequency division duplexing (FDD) cells and time division duplexing (TDD) cells.

[0131] Although FIG. 3B illustrates one example of a gNB 102, various changes may be made to FIG. 3B. For example, the gNB 102 can include any number of each component shown in FIG. 3B. As a particular example, an access point can include a number of interfaces 382, and the controller / processor 378 can support routing functions to route data between different network addresses. As another particular example, while shown as including a single instance of TX processing circuitry 374 and a single instance of RX processing circuitry 376, the gNB 102 can include multiple instances of each (such as one per RF transceiver).

[0132] Multiple input multiple output (MIMO) system wherein a BS and / or a UE is equipped with multiple antennas has been widely employed in wireless systems for its advantages in terms of spatial multiplexing, diversity gain and array gain.

[0133] FIG. 4 illustrates an exemplary cross-polarized MIMO antenna system.

[0134] FIG. 4 illustrates an example of MIMO antenna configuration with 48 antenna elements. Referring to FIG. 4, 4 cross-polarized 401 antenna elements form a 4x1 subarray. 12 subarrays form a 2V3H MIMO antennas configuration consisting 2 and 3 subarrays in vertical and horizontal dimensions, respectively. Although FIG. 4 illustrates one example of MIMO antenna configuration, the disclosed invention can be applied to various such configurations.

[0135] In MIMO systems, the channel state information (CSI) is required at the base station (BS) so that a signal from the BS is received at the UE with maximum possible received power and minimum possible interference. The acquisition of CSI at the BS can be via a measurement at the BS from an UL reference signal or via a measurement and feedback by the UE from a DL reference signal for time-domain duplexing (TDD) and frequency-domain duplexing (FDD) systems, respectively. In 5G FDD systems, the channel state information reference signal (CSI-RS) is the primary reference signal that is used by the UE to measure and report CSI.

[0136] In some embodiments, a UE may receive a configuration signaling from a BS for a CSI-RS that can be used for channel measurement. An example of such configuration is illustrated in FIG. 5.

[0137] FIG. 5 illustrates an exemplary layout for CSI-RS resource mapping in an OFDM time-frequency grid.

[0138] Referring to FIG. 5, 12 antenna ports (CSI-RS ports) are mapped to a CSI-RS with 3 code division multiplexing (CDM) groups, wherein each CDM group is mapped to 4 resource elements (REs) in OFDM time-frequency grid. The antenna ports that are mapped to the same CDM group can be orthogonalized in code-domain by employing orthogonal cover codes. The CSI-RS configuration in FIG. 5 can be related to the MIMO antenna configuration in FIG. 4, by mapping a CSI-RS port to one of the polarization of a subarray. In the 5G NR standards, three time-domain CSI-RS resources configurations, namely: periodic, semi-persistent and aperiodic are possible. In the FIG. 5, an illustrative example of periodic configuration is given with a period of 4 slots.

[0139] In some embodiments, the BS is capable of configuring a UE, by a higher layer signaling, with information for a CSI feedback that may include spatial channel information indicator and other supplementary information that would help the BS to have an accurate CSI. The spatial channel indicator, which is reported via a precoding matrix indicator (PMI) in 4G and 5G specifications, comprises a single or a plurality of channel matrix, the channel covariance matrix, the eigenvectors, or spatial sampling basis vectors. In particular, in 4G and 5G specification, the spatial channel information can be given by a single or a plurality of discrete Fourier transform (DFT) basis vectors.

[0140] FIG. 6 illustrates an example of precoder construction based on a plurality of DFT basis vectors for what is known as Type II CSI in 5G NR.

[0141] The spatial information of the channel is reported in terms of L=4 DFT basis vectors {b0, b1, b2, b3} 602 from a set of candidate DFT basis vectors 601. Additionally, amplitude information {p0, p1, p2, p3} 603 and co-phasing information (604) are reported. Thus, in Type II CSI a dual-stage precoding matrix is given asW=W1W2, where,W1select the DFT basis vectors andW2assign amplitude and co-phasing coefficients. Furthermore, a codebook can be defined as superset of candidate DFT basis vectors as well as candidate amplitude and phase coefficients. Then, a reported PMI would consist of indicators to the elements of a codebook that can represent the estimated channel.

[0142] In one exemplary embodiment, amplitude and phase information are reported in such a way that the linear combination of the basis vectors, i.e., , is matched to the eigenvector direction of the channel. Specifically, for a channel matrixHwith the (s,u)-th element hs,urepresenting the channel gain between the s-th transmit and the u-th receive antenna, the eigenvectors of the covariance matrixHHHcan be considered. Let denote one of the eigenvectors, then the PMI can be selected by the UE in such a way that the value is maximized.

[0143] Moreover, a UE can be configured in different ways to report a tuple of DFT basis vectors, amplitude coefficients and the phase coefficients, based on polarization-common or polarization-specific manner. For example, in 5G NR specifications, DFT basis vectors are reported in a polarization-common manner while phase and amplitude coefficients are reported in polarization specific manner, i.e., reported per polarization. MIMO systems allow spatial multiplexing, i.e., transmission of data in multiple transmission layers. In this regard, the type II CSI in the 5G NR allows the DFT basis vectors to be reported in a layer-common manner, i.e., common basis for all layers, while phase and amplitude coefficients to be reported in a layer-specific manner.

[0144] In order to account for the frequency-selectivity of a wideband channel, some embodiments allow various components of the precoding matrix, i.e., components of PMI, to be reported per frequency ranges. In some configurations, the frequency band the UE is configured for CSI reporting is partitioned into a set of subbands and the amplitude and / or phases coefficients are reported per a subband manner. In particular, the DL BWP can be partitioned in to subbands with subband size physical resource blocks (PRBs). Then the selected DFT basis vectors are linearly combined with different weights so that the resulting vector is aligned to the eigenvector of the channel in that subband. Denoting the set of subcarriers in the k-th subband as Fk, then the eigenvectors of the averaged covariance matrix can be considered, where, f∈Fkare subcarriers in the k-th subband andHf,kis the corresponding channel matrix.

[0145] FIG. 7A illustrates exemplary reporting precoding matrices in subband granularity.

[0146] FIG. 7A illustrates an example for frequency selective linear combination of DFT basis vectors 703 for K subbands of size 702 and L=4 DFT basis vectors (701).

[0147] In 5G NR specifications, another configuration, known as enhanced Type II (eType II) CSI, allows reporting amplitude and phase coefficients in a delay-domain rather than per subband reporting in frequency-domain. This configuration reduces the feedback overhead as the delay components are usually much smaller than the equivalent number of subbands. In enhanced Type II codebook (eType II CB) (FIG. 7B), precoding matrices are reported in delay domain by employing frequency-domain (FD) DFT basis rather than the frequency domain reporting in Type II CSI (FIG. 7A), i.e., per subband or wideband.

[0148] FIG. 7B illustrates an exemplary precoding matrix construction for eType II CSI.

[0149] Referring to FIG. 7B, a precoding matrix is expressed in three-stagesW=W1W2Wf(706). The spatial domain selection matrixW1selects L DFT vectors from P=2N1N2CSI-RS ports, consequently, it has 2L rows accounting for the cross-polarized antennas. Moreover, an Mv×N3matrix corresponds to MvDFT basis vectors (705) that can transform the precoding matrix reported in delay domain for Mvdelay components to a frequency domain with N3frequency domain points (bins) (704). In particular, the t∈{1,2,...,N3}-th element of f-th vector is given by . Finally, the matrixW2carries the amplitude and phase information wherein the i-th and j-th element, wi,j, carries amplitude (707) and phase (708) information of i-th 2D DFT beam and j-th delay component.

[0150] In order to further reduce the CSI overhead, a system may exploit angle-delay reciprocity and measure the dominant angle and delay components of a channel from an UL reference signal such as sounding reference signal (SRS). Then, a precoded CSI-RS can be considered for DL CSI measurement wherein the CSI-RS ports are mapped to an angle-delay component of the channel. Moreover, delay pre-compensation can be applied to the CSI ports so that the UE would measure CSI for a fewer number of delay components, i.e., in the extreme case for just one delay component.

[0151] Recently, artificial intelligence (AI)-based CSI feedback has gained considerable attention.

[0152] FIG. 8 illustrates an auto encoder (AE) based CSI feedback.

[0153] Referring to FIG. 8, an auto-encoder (AE) (800) includes an encoder part (801) at the UE (803) generating the CSI feedback and a decoder (802) at the gNB (804) reconstructing the CSI feedback. The main aim of an AE-based CSI feedback is to find the best representation of a channel state information in terms of feedback overhead. In another words, AE compresses the CSI to reduce the CSI feedback overhead.

[0154] The input for an auto-encoder can take different formats. In one embodiment, the input can be the eigenvectors of the channel. The covariance matrix of an Nt×Nrchannel matrixHgiven asHHHcan be computed by the UE. Then, the dominant eigenvectors of the covariance matrix given as V=[v1,...,vr] can be considered as an input for the auto-encoder.

[0155] FIG. 9 depicts an example for an auto encoder based CSI feedback according to an embodiment of the disclosure.

[0156] A set of Nschannel matrices which belong to Nssubbands, i.e., , is input (906) for a pre-processing unit (903). The preprocessing unit computes the Nseigenvectors and stacks them as a column of a matrix Vstack. The pre-processing unit transforms the estimated channel to stacked eigenvectors. Vstackis an input (907) for an encoder (901). An encoder (901) of the auto-encoder (900) then generates a CSI feedback in terms of a bit stream S (905). The decoder (902) part of the auto-encoder (900) takes the CSI feedback and reconstructs the stacked eignvectors. Moreover, a gNB then may use the reconstructed stacked eigenvectors as precoders.

[0157] The future networks will support a large number of antenna ports at the base station. As an example, in the frequency bands for future networks, e.g., mid-band (6GHz to 13GHz) for 6G mobile communication, the number of digitally controlled antenna ports in a single panel may dramatically increase, e.g., 256 ports, 512 ports. This increase in the number of antenna ports introduces a significant challenge for channel measurement. First, the CSI-RS overhead for antenna measurement increases by the same scale which diminishes the potential gain that could be achieved from the large number of ports. As an example, if the same time and frequency domain density for CSI-RS ports measurement is assumed, the increase in the number of antenna ports from 32 ports to 512 ports increases the CSI-RS overhead by 16 folds. Moreover, for a fixed transmission power, the per-port power for CSI-RS decreases by the same scale, incurring coverage challenged for CSI-RS measurement. Additionally, considering the legacy CSI-RS measurements, i.e., all the CSI-RS ports to be measured in a single resource block (RB), the increase in the CSI-RS ports may make it impossible to contain the ports in a single RB.

[0158] FIG. 10 illustrates an exemplary CSI-RS port mapping for 128 ports.

[0159] Referring to FIG. 10, 128 CSI-RS ports are mapped into an RB (10002) with 12×14=168 REs. As it is shown, for a CDM group with CDM8-FD2-TD4, i.e, 8 ports per CDM group wherein 2 subcarriers in frequency domain and 4 symbols in time domain, the maximum number of ports that can be supported is 128. For any arrangement of CDM groups, the maximum number of ports that can be mapped into a single RB is limited to 168. This implies, the same level of frequency granularity, i.e., RB-level for CSI-RS measurement, cannot be maintained.

[0160] The aforementioned limitations are applicable to other reference signals, e.g., SRS, demodulation reference signal (DMRS), etc., when the number of antenna ports increases, e.g., when the number of antenna ports at the UE increases, the SRS overhead increases.

[0161] The embodiments of the disclosure are described with reference to CSI-RS based measurements, it is to be understood that the scope of the disclosure is not limited thereto. The main principles, solutions and the corresponding embodiments of the disclosure are generic and can be readily be applied to other reference signals, e.g., SRS.

[0162] In the following, various methods to alleviate / resolve the aforementioned limitations are presented.

[0163] FIG. 11 illustrates a procedure for compressed CSI measurement and reporting according to an embodiment of the disclosure.

[0164] Referring to FIG. 11, in operation 11002, the network (11001) may configure the UE (11000) with a CSI report configuration. The CSI report configuration may include configuration information for CSI measurement. The configuration information for CSI measurement in the CSI report configuration may indicate CSI-RS resources with M CSI-RS ports (M is an integer). The CSI reporting configuration may further include a reporting configuration, e.g., codebook configuration, for the UE to report CSI quantities including at least one of PMI, channel quality indicator (CQI), rank indicator (RI), etc., for N CSI-RS ports (N is an integer). In operation 11003, the UE may receive DCI triggering a CSI report. In operation 11004, the UE may receive a CSI-RS on at least one CSI-RS resource with M ports. According to the configuration information for CSI measurement in the CSI reporting configuration, the UE may measure at least one CSI-RS resource with M ports. In operation 11005, the UE may report a CSI report consisting of at least one of PMI, CQI, RI, etc., for N ports.

[0165] When M<N, it can be referred as compressed CSI measurement. In this case, the network has to transform the N antenna ports to M measureable CSI-RS ports.

[0166] FIG. 12 illustrates an exemplary port transformation operation of a network according to an embodiment of the disclosure.

[0167] Referring to FIG.12, the network (12000) transforms the N antenna ports to M measureable CSI-RS ports (12004). The network transmits configuration information on M CSI-RS ports. The UE is configured with at least one CSI-RS resource with M ports (12001). The UE derives a CSI report for N ports (12003). The UE transmits the CSI report for N ports (12002).

[0168] The transformation process (12004) can also be referred as precoding, beamforming, virtualization, sampling or any other process that can transform the dimension of the channel measurement. In the disclosure, the term port transformation is used but the same process can be referred as precoding, beamforming, virtualization, sampling or any other process that can transform the dimension of the channel measurement.

[0169] In order for the UE to calculate a CSI corresponding to the N digitally controlled antenna ports based on measurement from M CSI-RS ports, the UE has to be informed with the transformation operation (12004) either explicitly or implicitly.

[0170] The transformation process in FIG. 12 can be represented a multiplication of an N-ports channel matrix denoted by with an M×N port transformation matrix denoted byA, where Nris the number of received antennas at the UE. Particularly, this is represented as Equation 1.

[0171] [Equation 1]

[0172]

[0173] where is the M-ports channel matrix which can be termed aspartial channel measurement.

[0174] The port transformation operation can take different forms. As an example, the network may sound a subset of the M antenna ports among the N digitally controlled antenna ports. This sampling process can be expressed by M×N ports transformation matrix. Equation 2 provides an example for sampling of M=4 antenna ports among N=8 antenna ports. In this case, if the element in thei-th row and j-th column is set to a value other than '0', e.g., '1', the UE may assume the j-th antenna port is sampled and mapped to i-th CSI-RS port. In the case of sampling, if M<N ports are mapped to the CSI-RS resource, the CSI-RS resource overhead and network's energy can be reduced by factor. Hereinafter, if there is a one-to-one mapping among the ports in the measured M ports and the ports in the N ports for the CSI report, the port transformation method can be termed asPortsSampling.

[0175] [Equation 2]

[0176]

[0177] In another exemplary case, the linear combining among ports can be considered. In this case, two or more antenna ports are combined or precoded by a combining a coefficients. Equation 3 provides an example for a combining operation for M=4 measured CSI-RS ports and N=8 antenna ports for CSI report. In this case, if the element in the i-th row and j-th column is set to a value other than '0', e.g., '1', the UE may assume the j-th antenna port is combined with other ports with a corresponding coefficients in the i-th row set to a value other than '0' and the linearly combined ports are mapped to i-th CSI-RS ports. Hereinafter, if there is a one-to-many mapping among the measured M ports and the N ports for the CSI report, the ports transformation method can be termed asPorts Combining.

[0178] [Equation 3]

[0179]

[0180] Similar toports samplingcase, in the case of ports combing, the CSI-RS overhead can be reduced by a factor of . Moreover, if the ports are combined in such a way that the maximum transmission power from the combined ports does not exceed the maximum transmission power of a single port, in other words, if for all i=1,...,M, then the network may save CSI-RS transmission energy by the factor of up to . In general, full channel (i.e., N ports) recovery from partial channel (i.e., M ports) measurement is more accurate in the case of combining as compared to sampling. This is because each of the N antenna ports can be measured indirectly by combining as compared to sampling.

[0181] The transformation matrix in Equation 1 can be formed based on some known sequences with special property, e.g., DFT, discrete cosine transform (DCT), Zadoff-Chu. Moreover, the coefficients of the transformation matrix can be determined by a learning method, e.g., as part of AI / ML model.

[0182] FIG. 13 illustrates an exemplary method for a learning based determination of the port transformation matrices, according to an embodiment of the disclosure.

[0183] In FIG. 13, the process of training the port transformation matrix (A) (13001) is depicted. The port transformation matrix can be trained separately or jointly with the channel recovery model (13004). Particularly, parameter updates on port transformation matrix (13001) and channel recovery model (13004) can be performed based on an end-to-end loss calculated on the ground truth full channelH(13000) and the recovered channel (13005). M port channel matrix Hc(13002) can be used for an input of the channel recovery model (13004).

[0184] The port transformation matrices can be explicitly configured by the network to the UE. In one aspect of the disclosure, the network may configure the UE with a port transformation matrix from a candidate set of port transformation matrices. This configuration can be given in the CSI report configuration. In another aspect of the disclosure, the network may configure the UE with a port transformation matrix by quantizing each element of the port transformation matrix, i.e., the quantized version of ai,j, for i=1,...,M and j=1,...,N. In one aspect, the coefficient ai,jcan be configured with amplitude information and phase information. Particularly, Kampand Kpbits can be used to represent the amplitude and phase of each coefficient by and levels. Thus, the coefficient ai,jcan be expressed in the form where α and β are the reported amplitude and phase coefficients, respectively. In some cases, the port transformation matrices may be sparse with most of the elements set to '0'. In this case, it's non-zero coefficients, e.g., a bitmap based, can be indicated with the corresponding amplitude and phase information for the indicated non-zero coefficients.

[0185] In some cases, an explicit configuration of the port transformation matrix may not be possible. The port transformation matrix can be considered as network's proprietary asset which cannot be disclosed to other vendors.

[0186] Moreover, the antenna panel structure, e.g., 2D planar, cylindrical, as well as the spacing between antenna elements and other factors may impact the performance of the recovery algorithm. Thus, the performance of AI / ML model trained based on a particular port transformation matrix on a particular network's antenna implementation may degrade when applied on another antenna implementation even if the same port transformation matrix is applied.

[0187] Moreover, the explicit configuration of coefficients may incur high overhead. As an example, if Kampand Kpbits are used to represent the amplitude and phase coefficients, respectively, for each coefficient of the M×N may require M×N×Kamp×Kpbits.

[0188] Considering the aforementioned limitations of explicit configurations of port transmission matrices, it is essential for the underlining relationship between the full channel measurements (H) and partial channel measurements (Hc)to be captured through training data collection. In order to capture this relationship, the UE may collect training data for full channel measurements (H) and partial channel measurements (Hc).

[0189] FIG. 14 illustrates an exemplary procedure for the data collection and inference pertinent to UE-side trained AI / ML model according to an embodiment of the disclosure.

[0190] The process of capturing the underlining relationship between the full and partial channel measurements is depicted in FIG. 14. In the data collection stage, the UE (14006) may perform the full channel measurements (H) and partial channel measurements (Hc). For this, the network (14000) may configure and transmit channel measurement resources (14001) to the UE. The estimated full channel (as a ground truth) and the partial channel are delivered (14002) from UE to a training server (14007), e.g., over-the-top (OTT) server. Alternatively, the UE may also use the estimated dataset for on-device training or fine-tuning. A model trained with the necessary optimization at the training server may be delivered to the UE (14003). Upon camping a certain cell of a network, the UE (14008) may receive an inference configuration (14004) that includes the necessary measurement and reporting configuration. Upon receiving the channel measurement resource for the partial channel measurement (14004), the UE may perform inference on the appropriate model, e.g., perform inference and report (14005) the result of the inference to the network.

[0191] In the UE-side training, as illustrated in FIG. 14, for the model inference, it is essential to ensure consistency with regards to the network-side settings which can also be termed as network-side additional conditions across model training and inference. The network-side additional conditions may include at least one of port transformation matrix, the downlink transmission filter for channel measurement resource, the antenna cross-correlation property, i.e., corresponding to antenna implementation, the antenna structure, or the antenna quasi-colocation (QCL) property that corresponds to the antenna panel.

[0192] To circumvent the practical limitations of explicit configuration of the network-side additional conditions, the network may indicate an associated ID that is associated to underlining network-side additional condition.

[0193] In one embodiment of the disclosure, the network may configure the UE with an implicit indication for the applied network-side additional conditions, wherein the implicit indication may be provided in the form of an associated ID in the measurement and reporting configurations for training and inference. The associated ID can be named as a model ID, a network-side setting ID (NSI ID), a dataset ID, or any other ID that achieves the purpose of ensuring consistency on the UE's assumption of the network-side additional condition. For the associated ID, the UE assumes consistency in at least one of the following network-side additional conditions including the relationship between the full ports and partial ports channels, i.e., port transformation matrix, the downlink transmission filter for channel measurement resource, the antenna cross-correlation property, i.e., corresponding to antenna implementation, the antenna structure, and the antenna quasi-colocation (QCL) property that corresponds to the antenna panel.

[0194] In one embodiment of the disclosure, the network may configure the UE with two sets of channel measurement resources (CMRs) and an associated ID:

[0195] - The first CMR set which can be termed as Set A for full channel measurement,

[0196] - The second CMR set which can be termed as Set B for partial channel measurement, and

[0197] - An associated ID.

[0198] For a pair of resources in Set A and Set B and an associated ID, the UE assumes consistency in at least one of the following network-side additional conditions including the relationship between the full ports and partial ports channels, i.e., port transformation matrix, the downlink transmission filter for channel measurement resource, the antenna cross-correlation property, i.e., corresponding to antenna implementation, the antenna structure, and the antenna quasi-colocation (QCL) property that corresponds to the antenna panel.

[0199] Table 1 shows one exemplary configuration for CMRs and associated ID. The CMRs for Set A and Set B as well as the associated ID may be provided in the CSI-ReportConfig.

[0200]

[0201] When the CSI report configuration is intended for data collection, the UE may not be expected to report the collected data to the network. In this case, the reportQuantity can be set to 'none'. The UE's behavior for the CSI report configurations with CSI reportQuantity set to 'none' may depend on other parameters of the configuration. As an example, when the UE is configured with a single set for channel measurement resources and the reportQuantity is set to 'none', the UE may use the configuration to determine the preferred receive filter. On the other hand, when the UE is configured with two sets of channel measurement resources and a corresponding reportQantity set to 'none', the UE may assume the configuration is for data collection.

[0202] Similarly, an exemplary configuration for the purpose of inference is shown in Table 2 below. The inference configuration can be provided as a CSI report configuration. The network may configure the UE with at least one CMR set for Set B, i.e., partial channel measurement and the corresponding associated ID. The network may additionally configure a CMR set for Set A, i.e., full channel measurement. The configuration of the CMR set for Set A can be optional. Thus, the UE is not expected to measure the CMRs for Set A for inference purpose. Additionally, the network may configure the UE with a reportQuantity for the CSI report which can be at least one of the candidates including cri-RI-PMI-CQI, cri-RI-PMI-CQI-LI, cri-RI-CQI, and other CSI reportQuantity for AI / ML based CSI reporting.

[0203] 'cri' represents a CSI-RS resource indicator, and 'LI' represents a layer indicator.

[0204]

[0205] In some cases, the network may apply multiple channel measurement compression ratios, i.e., the ratio of the number of ports in the partial and full channel measurements, i.e., . In this case, the network may configure the UE with a configuration for data collection wherein the configuration may contain a single CMR resource for full channel measurement, i.e., Set A, and multiple CMRs for the partial channel measurement, i.e., Set B.

[0206] FIG. 15 illustrates an exemplary configuration with one-to-many mapping between the CMRs for full channel measurement and partial ports measurements according to an embodiment of the disclosure.

[0207] Referring to FIG. 15, the network may configure a single CMR (15000) for Set A and K CMR resources (15001, 15002, 15003) for Set B. The k-th CMR resource in Set B (15002) may contain Mkports, thus, a measurement compression ratio of and associated with the port transformation matrixAk(15004).

[0208] In one embodiment of the disclosure, the network may configure the UE with a configuration for data collection, wherein the configuration includes:

[0209] - The first CMR set for full channel measurement, i.e., Set A, with a single CMR,

[0210] - The second CMR set for partial channel measurement, i.e., Set B, with K>1 CMRs, and

[0211] - K associated IDs.

[0212] Wherein the first associated ID is applied to the first CMR in Set B, the second associated ID is applied to the second CMR in Set B, and so on, where associated IDs are applied based on the ordinal position of their configuration the corresponding CMRs in Set B. For a pair of resources in Set A and Set B and an associated ID, the UE assumes consistency in at least one of the following network-side additional conditions including the relationship between the full ports and partial ports channels, i.e., port transformation matrix, the downlink transmission filter for channel measurement resource, the antenna cross-correlation property, i.e., corresponding to antenna implementation, the antenna structure, and the antenna quasi-colocation (QCL) property that corresponds to the antenna panel.

[0213] In one embodiment of the disclosure, the network may configure the UE with a configuration for data collection wherein the configuration may include:

[0214] - The first CMR set for full channel measurement, i.e., Set A, with a single CMR,

[0215] - The second CMR set for partial channel measurement, i.e., Set B, with K>1 CMRs, and

[0216] - single associated ID.

[0217] For the same associated ID and number of ports in Set B, the UE assumes consistency in at least one of the following network-side additional conditions including the relationship between the full ports and partial ports channels, i.e., ports transformation matrix, the downlink transmission filter for channel measurement resource, the antenna cross-correlation property, i.e., corresponding to antenna implementation, the antenna structure, and the antenna quasi-colocation (QCL) property that corresponds to the antenna panel. Thus, if such configuration is possible, the UE considers both the associated ID and the number of ports for CMR in Set B to determine the consistency on network-side additional conditions.

[0218] In some cases, the network is interested in sub-selection based port transformation matrices only. In this case, data collection may require a single CMR configuration for both full channel measurement and partial channel measurement.

[0219] In one embodiment of the disclosure, the network may configure the UE with a configuration for data collection wherein the configuration may include:

[0220] - A CMR set with at least one CMR resource for full channel and partial ports measurements,

[0221] - Indication and / or a configuration for port transformation matrix (A), and

[0222] - At least one associated ID.

[0223] The UE may determine to perform the measurement for the partial channel measurements based on configured CMR by selecting the ports indicated by the port transformation matrix, e.g., bitmap based indication. Moreover, for the same associated ID and the number of ports in the CMR set, the UE assumes consistency in at least one of the following network-side additional conditions including the relationship between the full ports and partial ports channels, the downlink transmission filter for channel measurement reference resource, the antenna cross-correlation property, i.e., corresponding to antenna implementation, the antenna structure, and the antenna quasi-colocation (QCL) property that corresponds to the antenna panel. When more than one associated IDs and more than one port transformation matrices are configured, the mapping of associated IDs to the port transformation matrices is given based on the ordinal position of their configuration. In other words, the first associated ID is applied to the first port transformation matrix, the second associated ID is applied to the second port transformation matrix, and so on where associated IDs are applied based on the ordinal position of their configuration the corresponding port transformation matrices.

[0224] The availability, applicability and configurations of measurements for data collection may depend on various factors and situations of the network and the UE. As an example, the network's situation such as the traffic load, the energy saving strategy and other factors may determine on the availability and configurations related to data collection. On the other hands, the UE's situation such as the UE's preferred configuration, other internal states such as power, computational resources, etc. Thus a mechanism that ensures alignment on the network's and UE's preferences in regards to the data collection is required.

[0225] FIG. 16 illustrates an exemplary procedure for data collection related capability and preference indications between the UE and the network, according to an embodiment of the disclosure.

[0226] Referring to FIG. 16, the network and the UE perform handshake on their preferences on the availability of data collection related configurations with the following procedure.

[0227] In operation 16002, the network (16001) may inquire the UE (16000) on the UE's capability report including inquiry for data collection related capability report. The inquiry may include the list of the associated ID supported by the network for each feature.

[0228] In operation 16003, the UE may report its capability report. The capability report may include conditions for the configuration of data collection regarding compressed channel measurements. The capability report may include supported parameters for the number of ports for full ports (N) and partial ports (M), and their possible combinations.

[0229] In operation 16004, following the UE's capability report, the network may configure the UE with candidate configurations for data collection (or a list of configurations for data collection). The configuration may include the corresponding associated ID.

[0230] In accordance to the network's candidate configurations in operation 16004, the UE may indicate the preferred configuration for data collection in operation 16005. This indication can be provided in uplink control information (UCI), or MAC-CE, or as UE assistance information (UAI) report.

[0231] In operation 16006, based on UE's indication of the preferred data collection related configurations, the network may activate or trigger the data collection related configurations. The network may also deactivate the configurations. Activation or triggering in operation 16006 can be rendered via MAC-CE, downlink control information (DCI) or other downlink messages.

[0232] Meanwhile, although specific embodiments of the disclosure have been described in detail, various modifications may be made without departing from the scope of the disclosure. Therefore, the scope of the disclosure should not be limited to the described embodiments, but should be defined by the claims and equivalents thereof.

Claims

1.A method performed by a user equipment (UE) in a wireless communication system, the method comprising:receiving configuration information on a channel state information (CSI) report;receiving channel state information reference signal (CSI-RS) on at least one CSI-RS resource with M ports based on the configuration information;calculating a CSI parameter for N ports based on the CSI-RS; andtransmitting the CSI report including the CSI parameter for N ports,wherein M and N are integers and M < N.2.The method of claim 1,wherein the configuration information includes a port transformation matrix that transforms the N ports to the M ports.3.The method of claim 1,wherein the configuration information further includes a channel measurement resource (CMR) set and at least one associated identity (ID),wherein the method further comprises:performing partial channel measurement based on the CMR set by selecting M ports indicated by the port transformation matrix.4.The method of claim 1,wherein the configuration information includes a first channel measurement resource (CMR) set for full channel measurement corresponding to the N ports, a second CMR set for partial channel measurement corresponding to the M ports, and at least one associated identity (ID).5.The method of claim 4,performing the full channel measurement based on the first CMR set; andperforming the partial channel measurement based on the second CMR set.6.The method of claim 4,wherein the UE assumes consistency in a relationship between the M ports and the N ports based on the at least one associated ID.7.The method of claim 1, further comprising:transmitting a capability report including information indicating, respectively, a number of M ports and a number of N ports that the UE is configured to support.8.A method performed by a base station (BS) in a wireless communication system, the method comprising:transmitting, to a user equipment (UE) configuration information on a channel state information (CSI) report;transmitting, to the UE, channel state information reference signal (CSI-RS) on at least one CSI-RS resource with M ports based on the configuration information; andreceiving, from the UE, the CSI report including a CSI parameter for N ports,wherein the CSI parameter for N ports is derived based on the CSI-RS, andwherein M and N are integers and M < N.9.The method of claim 8,wherein the configuration information includes a port transformation matrix that transforms the N ports to the M ports.10.The method of claim 8,wherein the configuration information includes a first channel measurement resource (CMR) set for full channel measurement corresponding to the N ports, a second CMR set for partial channel measurement corresponding to the M ports, and at least one associated identity (ID).11.The method of claim 10,wherein the at least one associated ID indicates consistency in a relationship between the M ports and the N ports.12.The method of claim 8, further comprising:receiving, from the UE, a capability report including information indicating, respectively, a number of M ports and a number of N ports that the UE is configured to support.13.A user equipment (UE) in a wireless communication system, the UE comprising:at least one transceiver; andat least one processor coupled with the at least one transceiver and configured to:receive configuration information on a channel state information (CSI) report,receive channel state information reference signal (CSI-RS) on at least one CSI-RS resource with M ports based on the configuration information,calculate a CSI parameter for N ports based on the CSI-RS, andtransmit the CSI report including the CSI parameter for N ports,wherein M and N are integers and M < N.14.The UE of claim 13,wherein the configuration information includes a port transformation matrix that transforms the N ports to the M ports, a channel measurement resource (CMR) set and at least one associated identity (ID),wherein the UE assumes consistency in a relationship between the M ports and the N ports based on the at least one associated ID, andwherein the at least one processor is further configured to perform partial channel measurement based on the CMR set by selecting M ports indicated by the port transformation matrix.15.A base station (BS) in a wireless communication system, the BS comprising:at least one transceiver; andat least one processor coupled with the at least one transceiver and configured to:transmit, to a user equipment (UE) configuration information on a channel state information (CSI) report,transmit, to the UE, channel state information reference signal (CSI-RS) on at least one CSI-RS resource with M ports based on the configuration information, andreceive, from the UE, the CSI report including a CSI parameter for N ports,wherein the CSI parameter for N ports is derived based on the CSI-RS, andwherein M and N are integers and M < N.

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