Method for transmitting channel state information reference signals

Abstract

The present disclosure relates to a method for transmitting channel state information reference signal (CSI-RS). The method includes setting, at a base station, CSI-RS transmission configuration information including one or more code division multiplexing (CDM) groups, resource elements (REs) in each CDM group having uniform frequency distribution; transmitting the CSI-RS transmission configuration information from the base station (BS) to a user equipment (UE); generating, for each antenna port of the BS, a CSI-RS modulated across resource elements in a frequency domain (FD) according to a discrete Fourier transform (DFT) vector by an orthogonal cover code (OCC) and across one or more orthogonal frequency division multiplexing (OFDM) symbols in a time domain (TD) according to a Walsh-Hadamard (WH) code; and transmitting the CSI-RS from the BS to the UE according to the CSI-RS transmission configuration.

Description

Technical Field

[0001] This disclosure relates to wireless communication. More specifically, this disclosure relates to a method for transmitting channel state information reference signals. Background Technology

[0002] Given the successive generations of development in wireless communication, technologies have been developed primarily for human-facing services such as voice calls, multimedia services, and data services. With the commercialization of 5G (fifth-generation) communication systems, the number of connected devices is expected to grow exponentially. These devices will increasingly connect to communication networks. Examples of connected things can include vehicles, robots, drones, home appliances, displays, smart sensors connected to various infrastructures, construction machinery, and factory equipment. Mobile devices are expected to evolve into various forms, such as augmented reality glasses, virtual reality headsets, and holographic devices. To provide a wide range of services by connecting hundreds of billions of devices and things in the 6G (sixth-generation) era, the industry has been working to develop improved 6G communication systems. For these reasons, 6G communication systems are referred to as "beyond 5G" systems.

[0003] The 6G communication system, expected to be commercialized around 2030, will have peak data rates in the terabyte (1000 gigabyte) range and wireless latency of less than 100 microseconds (μsec), and will therefore be 50 times faster than 5G communication systems with 1 / 10 of their wireless latency.

[0004] To achieve such high data rates and ultra-low latency, 6G communication systems have been considered for implementation in terahertz bands (e.g., the 95 GHz to 3 THz band). Since path loss and atmospheric absorption in the terahertz band are more severe than those in the millimeter-wave (mmWave) band introduced in 5G, technologies that can ensure signal transmission distance (i.e., coverage) are expected to become even more critical. As key technologies for ensuring coverage, it is necessary to develop radio frequency (RF) components, antennas, new waveforms with better coverage than orthogonal frequency division multiplexing (OFDM), beamforming and massive MIMO, full-dimensional MIMO (FD-MIMO), array antennas, and multi-antenna transmission technologies (such as massive MIMO). Furthermore, the industry has been discussing new technologies for improving the coverage of terahertz band signals, such as metamaterial-based lenses and antennas, orbital angular momentum (OAM), and reconfigurable smart surfaces (RIS).

[0005] Furthermore, to improve spectrum efficiency and overall network performance, the following technologies have been developed for 6G communication systems: full-duplex technology to enable uplink and downlink transmissions to use the same frequency resources simultaneously; network technologies to utilize satellites, high-altitude platform stations (HAPS), etc., in an integrated manner; improved network architectures to support mobile base stations and achieve network operation optimization and automation; dynamic spectrum sharing technology via conflict avoidance based on spectrum usage prediction; the use of AI in wireless communication to improve the entire network operation by leveraging artificial intelligence (AI) from the design phase of 6G development and internalizing end-to-end AI support functions; and next-generation distributed computing technologies to overcome the limitations of UE computing capabilities through ultra-high-performance communication and computing resources accessible on the network, such as mobile edge computing (MEC), cloud, etc. In addition, ongoing efforts are underway to design new protocols for use in 6G communication systems, develop mechanisms for achieving hardware-based secure environments and secure data use, develop technologies for maintaining privacy, enhance connectivity between devices, optimize networks, promote the software-defined networking of network entities, and increase the openness of wireless communication.

[0006] The research and development of 6G communication systems in hyper-connectivity (including human-to-machine (P2M) and machine-to-machine (M2M)) is expected to enable next-generation hyper-connected experiences. Specifically, services such as truly immersive extended reality (XR), high-fidelity mobile holograms, and digital twins are anticipated to be available through 6G communication systems. Furthermore, services such as remote surgery for enhanced security and reliability, industrial automation, and emergency response will be provided through 6G communication systems, enabling these technologies to be applied in various fields such as industry, healthcare, automotive, and home appliances.

[0007] The massive multiple-input multiple-output (mMIMO) architecture in the fifth-generation (5G) new wireless (5G NR) communication standard improves spectral efficiency performance by using an antenna system with multiple antenna elements and advanced processing schemes.

[0008] The ultra-large-scale MIMO (xMIMO) antenna system for future sixth-generation (6G) communication standards is designed to provide even better performance due to support for even larger antenna arrays and wider system bandwidth.

[0009] To implement mMIMO and xMIMO operations, channel state information (CSI) feedback can be used: - Based on reciprocity, the sounding reference signal (SRS) is used to provide channel measurements at the base station (BS). - Based on the codebook, where the quantized CSI is calculated by the user equipment (UE) and provided to the BS using uplink control information (UCI).

[0010] To support codebook-based CSI feedback, the Channel State Information Reference Signal (CSI-RS) is transmitted from the BS to the UE. Summary of the Invention

[0011] [Technical Issues]

[0012] The existing CSI-RS technology in 5G NR supports up to 32 antenna ports and is also modulated by quadrature phase shift keying (QPSK) symbols and transmitted over the system bandwidth.

[0013] However, the current CSI-RS architecture is insufficient to support xMIMO operation with more than 32 antenna ports, such as up to 256 antenna ports.

[0014] According to TS 38.211 "NR; Physical Channels and Modulation" v17.5.0 released on June 26, 2023, the CSI-RS architecture of 5G NR provides key features: -CSI-RS uses pseudo-random sequences for QPSK modulation; - Configurable bandwidth (BW) and common reference points for sequence generation; -Supports up to 32 antenna ports; - Signal density (the number of resource elements per antenna port) is selected from 0.5, 1, 3 (for a single port only); - Non-periodic, semi-persistent, and periodic transmission of CSI-RS within the same time slot; - Code division multiplexing (CDM) groups always contain adjacent resource elements (REs).

[0015] In addition, CSI-RS port multiplexing provides: - Multiplexing options: Time-domain orthogonal overlay code (TD-OCC), frequency-domain orthogonal overlay code (FD-OCC), frequency division multiplexing (FDM), time division multiplexing (TDM). - In addition to the CSI-RS with one port, the REs in each CDM group are not uniformly distributed; -Port index: First in the CDM group, then across the frequency domain in the CDM group, and then in the time domain.

[0016] Due to the aforementioned characteristics of the CSI-RS structure in 5G NR, adjacent REs in a CDM group may not allow the transmission of other reference signals within the same group, i.e., it is prone to generating potential scheduling constraints. CSI-RS always transmits in the same time slot, consuming a significant amount of resources. The CSI-RS structure with non-uniform CDM groups is only suitable for Cyclic Prefix Orthogonal Frequency Division Multiplexing (CP-OFDM) and cannot be extended for low peak-to-average power ratio (PAPR) waveforms.

[0017] 6G communication systems deployed in the mid-to-high frequency band (10-12 GHz) should support a greater number of antenna ports than 5G NR (i.e., more than 32), because 6G systems assume the use of antenna arrays with a very large number of antenna ports (xMIMO). Furthermore, more CSI-RS signals will be needed to obtain the channel characteristics of these ports, since in the simplest xMIMO scenario, one CSI-RS signal is required for the configuration and transmission of one antenna port.

[0018] Therefore, the existing CSI-RS architecture for 5G NR described above is insufficient to support 6G communication systems due to the following issues: The maximum number of CSI-RS antenna ports (up to 32) is less than the number required for 6G xMIMO (up to 256). - The 5G NR CSI-RS architecture only supports CP-OFDM and cannot be extended to low PAPR waveforms; - The 5G NR CSI-RS structure is not flexible enough to transmit other reference signals simultaneously; - The reduced overhead of 5G NR did not optimize for subband architecture; -CSI-RS transmission is always limited to the same time slot; - Port indexing does not support sharing CSI-RS resources with a different number of ports.

[0019] Therefore, there is a need in the art for a method for generating and transmitting CSI-RS that offers greater flexibility and performance and is suitable for 6G xMIMO systems.

[0020] The above information is presented as background information only to aid in understanding this disclosure. No decision has been made, nor any assertion, regarding whether any of the above content applies as prior art to this disclosure.

[0021] [Solution to the problem]

[0022] The aspects of this disclosure are intended to at least address the aforementioned problems and / or disadvantages, and to provide at least the advantages described below. Therefore, one aspect of this disclosure is to provide a method for transmitting channel state information reference signals.

[0023] Other aspects will be set forth in part in the description below, and will be partly apparent from the description or may be learned through the practice of the presented implementation schemes.

[0024] According to one aspect of this disclosure, a method for transmitting a Channel State Information Reference Signal (CSI-RS) is provided. The method includes: setting CSI-RS transmission configuration information at a base station, the CSI-RS transmission configuration information including one or more code division multiplexing (CDM) groups, each CDM group having resource elements (REs) with a uniform frequency distribution; transmitting the CSI-RS transmission configuration information from the base station (BS) to a user equipment (UE); generating a CSI-RS for each antenna port of the base station, the CSI-RS being modulated across resource elements in the frequency domain (FD) according to a discrete Fourier transform (DFT) vector using orthogonal coverage codes (OCC), and modulated across one or more OFDM symbols in the time domain (TD) according to Walsh-Hadamard (WH) codes; and transmitting the CSI-RS from the BS to the UE according to the CSI-RS transmission configuration.

[0025] In embodiments of this disclosure, the CSI-RS transmission configuration information further includes at least one of the following: information about the number of ports, information about the number of CDM groups, the length of the OCC in time and frequency, CSI-RS port index information, the CSI-RS waveform used, the OFDM symbols and time slots used, or the physical resource block (PRB) group where CSI-RS exists.

[0026] In another embodiment of this disclosure, the generation of CSI-RS includes modulating the CSI-RS sequence using quadrature phase shift keying (QPSK) symbols obtained based on a pseudo-random sequence.

[0027] In another embodiment of this disclosure, the generation of CSI-RS includes modulating the CSI-RS sequence using p / 2 binary phase shift keying (p / 2-BPSK) symbols obtained based on a pseudo-random sequence.

[0028] In another embodiment of this disclosure, the generation of CSI-RS includes modulating the CSI-RS sequence using a Zadoff-Chu (ZC) sequence.

[0029] In another embodiment of this disclosure, the PRB group includes two or more adjacent PRBs, which are spaced at the same or similar distance from each other in the frequency domain.

[0030] In another embodiment of this disclosure, CDM groups are transmitted on non-adjacent OFDM symbols in a time slot.

[0031] In another embodiment of this disclosure, signaling is used to indicate to the UE the actual OFDM symbol used for CSI-RS.

[0032] In another embodiment of this disclosure, in the event of a transmission conflict with other signals, the actual OFDM symbol used for CSI-RS is determined by the base station by delaying the subsequent transmission of all or part of the OFDM symbols of CSI-RS to subsequent OFDM symbols.

[0033] In another embodiment of this disclosure, the other signal is a tracking reference signal (TRS) transmitted by the BS.

[0034] In another embodiment of this disclosure, the first and last symbols of CSI-RS are in different time slots.

[0035] In another embodiment of this disclosure, a subset of the CSI-RS ports is transmitted on one timeslot, and another subset of the CSI-RS ports is transmitted on another timeslot.

[0036] In another embodiment of this disclosure, a first subset and a second subset of antenna ports correspond to different polarizations.

[0037] In another embodiment of this disclosure, the CSI-RS corresponding to a smaller number of antenna ports is a subset of the CSI-RS corresponding to a larger number of antenna ports.

[0038] In another embodiment of this disclosure, the antenna ports of the CSI-RS are indexed in the following order: first across CDM groups, and then by OCC code within the CDM group.

[0039] According to another aspect of this disclosure, a method for communication in a communication system including at least one base station and at least one user equipment is provided. The method includes: transmitting CSI-RS from the base station to the user equipment; configuring the user equipment to receive CSI-RS based on the received CSI-RS; measuring channel characteristics from a transmission port of the base station and acquiring channel state information; transmitting the channel state information to the base station; selecting transmission parameters of a Physical Downlink Shared Channel (PDSCH) based on the channel state information; and generating a signal and transmitting the signal to the user equipment on the PDSCH channel.

[0040] In embodiments of this disclosure, the transmission parameters of the PDSCH include the spatial precoding matrix, the modulation scheme, and the noise-resistant coding rate of the PDSCH.

[0041] According to another aspect of this disclosure, a base station is provided in a communication system including a user equipment. The base station is configured to: set channel state information reference signal (CSI-RS) transmission configuration information, the CSI-RS transmission configuration information including one or more code division multiplexing (CDM) groups, each CDM group having resource elements (REs) with a uniform frequency distribution; transmit the CSI-RS transmission configuration information to the user equipment (UE); generate a CSI-RS for each antenna port of the base station, the CSI-RS being modulated across resource elements in the frequency domain (FD) according to a discrete Fourier transform (DFT) vector via OCC, and modulated across one or more OFDM symbols in the time domain (TD) according to a Walsh-Hadamard (WH) code; and transmit the CSI-RS to the UE according to the CSI-RS transmission configuration.

[0042] According to another aspect of this disclosure, one or more non-transitory computer-readable storage media are provided that store computer-executable instructions that, when executed individually or jointly by one or more processors, cause a base station to perform operations. The operations include: setting CSI-RS transmission configuration information at the base station, the CSI-RS transmission configuration information including one or more code division multiplexing (CDM) groups, each CDM group having resource elements (REs) with a uniform frequency distribution; transmitting the CSI-RS transmission configuration information from the base station (BS) to the user equipment (UE); generating a CSI-RS for each antenna port of the base station, the CSI-RS being modulated across resource elements in the frequency domain (FD) according to a discrete Fourier transform (DFT) vector using orthogonal coverage codes (OCC), and modulated across one or more OFDM symbols in the time domain (TD) according to Walsh-Hadamard (WH) codes; and transmitting the CSI-RS from the BS to the UE according to the CSI-RS transmission configuration.

[0043] This disclosure provides a higher performance and more flexible CSI-RS generation and transmission architecture, a unified CSI-RS structure, and reduced transmission overhead.

[0044] Other aspects, advantages, and distinctive features of this disclosure will become apparent to those skilled in the art from the following detailed description of various embodiments thereof, taken in conjunction with the accompanying drawings.

[0045] [Beneficial effects of the invention]

[0046] This disclosure provides a method and apparatus for generating and transmitting CSI-RS, which offers greater flexibility and performance and is suitable for 6G xMIMO systems. Attached Figure Description

[0047] The above and other aspects, features and advantages of certain embodiments of the present disclosure will become more apparent from the following description taken in conjunction with the accompanying drawings, wherein: Figure 1 This is a schematic diagram illustrating the distribution of resource elements in a CDM group according to an embodiment of the present disclosure; Figure 2 The diagram illustrates the sequential resource elements in the frequency domain (left) and time domain (right) to which OCC elements from the same CDM group are mapped according to an embodiment of this disclosure; Figure 3 It is the CSI-RS structure according to the embodiments of this disclosure; Figure 4A is a flowchart illustrating CSI-RS modulation algorithms for xMIMO according to various embodiments of the present disclosure; Figure 4B is a flowchart illustrating CSI-RS modulation algorithms for xMIMO according to various embodiments of the present disclosure; Figure 4C is a flowchart illustrating CSI-RS modulation algorithms for xMIMO according to various embodiments of the present disclosure; Figure 5A shows the PRB distribution of CSI-RS according to various embodiments of this disclosure; Figure 5B shows the PRB distribution of CSI-RS according to various embodiments of this disclosure; Figure 5C shows the PRB distribution of CSI-RS according to various embodiments of this disclosure; Figure 6 The CSI-RS structure in the time domain, according to an embodiment of this disclosure, is shown in the case of conflict with other reference signals in the prior art. Figure 7 This illustrates CSI-RS transmission over two adjacent time slots in a 6G system according to an embodiment of this disclosure; Figure 8 The present disclosure illustrates CSI-RS transmissions via two sets of antenna ports in two different time slots in a 6G system according to an embodiment of the present disclosure. Figure 9 An embodiment of the present disclosure is shown for use in accordance with... Figure 8 The transmission uses two sets of antenna ports with different polarizations for CSI-RS transmission. Figure 10 It is a CSI-RS structure according to an embodiment of this disclosure, having resources shared for different numbers of antenna ports; Figure 11 This is a schematic diagram illustrating the indexing of the antenna ports of the CSI-RS according to an embodiment of this disclosure; Figure 12 This illustrates the basis for the embodiments according to this disclosure. Figure 11A schematic diagram of the signal structure transmission of CSI-RS received by the user equipment; and Figure 13 This is a flowchart illustrating a communication method in a communication system according to an embodiment of the present disclosure.

[0048] Figure 14 This is a block diagram of a terminal according to an embodiment of this disclosure.

[0049] Figure 15 This is a block diagram of a base station according to the implementation scheme of this disclosure.

[0050] In all the accompanying drawings, the same reference numerals are used to denote the same elements. Detailed Implementation

[0051] The following description, with reference to the accompanying drawings, is provided to aid in a full understanding of the various embodiments of this disclosure as defined by the claims and their equivalents. This description includes various specific details to aid understanding, but these are to be considered exemplary only. Therefore, those skilled in the art will recognize that various changes and modifications can be made to the various embodiments described herein without departing from the scope and spirit of this disclosure. Furthermore, for clarity and brevity, descriptions of well-known functions and structures may be omitted.

[0052] The terms and words used in the following description and claims are not limited to their dictionary literal meanings, but are used solely by the inventors to achieve a clear and consistent understanding of this disclosure. Therefore, those skilled in the art will understand that the following description, which provides various embodiments of this disclosure, is for illustrative purposes only and is not intended to limit the disclosure as defined by the appended claims and their equivalents.

[0053] It should be understood that the singular forms “a,” “an,” and “the” include plural referents unless the context explicitly specifies otherwise. Thus, for example, referring to “the surface of a component” includes referring to one or more such surfaces.

[0054] The structure of the Channel State Information Reference Signal (CSI-RS) according to this disclosure is described below.

[0055] According to this disclosure, multiple (CDM) groups have a uniform frequency distribution of resource elements (transmission comb structure) in each CDM group. A CDM group is a set of subcarriers in which several signals with orthogonal sequences can be multiplexed.

[0056] It should be understood that each flowchart and the boxes in a combination of flowcharts can be executed by one or more computer programs that include computer-executable instructions. The entirety of the one or more computer programs can be stored in a single memory device, or the one or more computer programs can be divided into different parts stored in multiple different memory devices.

[0057] Any function or operation described herein may be processed by a single processor or combination of processors. This single processor or combination of processors is circuitry that performs the processing and includes, for example, an application processor (AP, such as a central processing unit (CPU)), a communication processor (CP, such as a modem), a graphics processing unit (GPU), a neural processing unit (NPU) (e.g., an artificial intelligence (AI) chip), a Wi-Fi chip, or Bluetooth. TM Circuits such as chips, global positioning system (GPS) chips, near field communication (NFC) chips, connectivity chips, sensor controllers, touch controllers, fingerprint sensor controllers, display driver integrated circuits (ICs), audio codec chips, universal serial bus (USB) controllers, camera controllers, image processing ICs, microprocessor units (MPUs), system-on-a-chip (SoCs) or ICs.

[0058] Figure 1 This is a schematic diagram illustrating the distribution of resource elements (subcarriers) in a CDM group according to an embodiment of the present disclosure.

[0059] refer to Figure 1 , N CDM,max = 2, where N CDM,max This is the specified maximum number of CDM groups. A second CDM group can be obtained by shifting the described comb structure by one subcarrier.

[0060] Similarly, in Figure 1 In the middle, the center and the right side respectively show when N CDM,max = 4 and N CDM,max = 8 represents a uniform distribution of resource elements within the same CDM group. Other CDM groups can also be obtained by shifting the comb-like structure shown.

[0061] The uniform frequency RE in the CDM group supports low PAPR waveforms.

[0062] When generating CDM groups with a uniform frequency distribution of resource elements, orthogonal code division is applied to each CDM group. This method... Figure 3 The diagram shows two CDM groups, one with a uniform frequency distribution of resource elements and the other with a continuous-time distribution of resource elements, illustrated by different shaded lines (horizontal and vertical). In the frequency domain, Figure 3The CDM groups are shifted relative to each other by a frequency interval between subcarriers. On the same resource element within each CDM group, CSI-RS signals transmitted through different antenna ports use code division, specifically multiplexing using a combination of orthogonal frequency (FD-OCC) and time (TD-OCC) codes.

[0063] In the frequency domain within a CDM group, Discrete Fourier Transform (DFT) codes are used for partitioning. Therefore, according to this disclosure, in the frequency domain (FD), cyclic shifting is used to multiplex multiple CSI-RS antenna ports within the same CDM group using DFT codes.

[0064] DFT-based FD-OCC provides low-complexity Fast Fourier Transform (FFT) channel estimation and low PAPR waveforms. The FD-OCC sequence obtained through Discrete Fourier Transform... The element (i.e., the code division sequence or multiplexed element mapped to the sequential resource element (RE) in the frequency domain) is defined as follows: Equation 1 Where k' is the RE index in the CDM group. N f,max It is the number of orthogonal codes in the frequency domain. k f It is the variable that uniquely corresponds to the FD-OCC code index in a CDM group. j is the imaginary unit.

[0065] The time-domain (TD) method of this disclosure uses a binary Walsh-Hadamard sequence to multiple CSI-RS antenna ports on multiple orthogonal frequency division multiplexing (OFDM) symbols of a CDM group.

[0066] Compared to OCC codes obtained using DFT, WH-based TD-OCC is easier to implement and more robust to frequency shifts. TD-OCC sequences are derived from orthogonal Walsh-Hadamard sequences. An element (i.e., an element of a code division or multiplexing sequence mapped to a sequential resource element (RE) in the time domain) is defined as: Equation 2 in l ' is the index of the OFDM symbol in the CDM group. N t,max It is the number of OFDM symbols that define the code length in the time domain. It is a variable representing a set of Walsh-Hadamard sequences (or a Walsh-Hadamard matrix, where each column of the matrix represents a separate sequence). In Equation 2 The usage explains how to recursively obtain a set of Walsh-Hadamard sequences from a Walsh-Hadamard sequence whose length has been halved.

[0067] In special circumstances, when N t,max When = 2, equation 2 takes the following form: .

[0068] Figure 2 The diagram illustrates the sequential resource elements in the frequency domain (left) and time domain (right) to which orthogonal overlay code (OCC) elements from the same CDM group according to an embodiment of this disclosure are mapped.

[0069] Therefore, the left side shows the FD-OCC CDM group, and the right side shows the TD-OCC CDM group. Furthermore, although the elements are arranged consecutively in the time domain (right side), in the frequency domain (left side), the resource elements of the CSI-RS CDM group are interleaved with resource elements not occupied by that CSI-RS signal. The idle resource elements between resource elements of one CDM group in the frequency domain can be used to transmit CSI-RS to another CDM group. This achieves frequency division between CDM groups for the CSI-RS signal. Figure 2 As shown, N f,max = 4 (for CDM groups in the frequency domain), and N t,max = 8 (for CDM groups in the time domain).

[0070] Maximum number of antenna ports for CSI-RS Defined by the following equation: ...Equation 3.

[0071] Figure 3 The CSI-RS structure according to an embodiment of this disclosure is shown.

[0072] refer to Figure 3 It shows that it is aimed at N CDM,max = 2、 N f,max = 4 and N t,max The CSI-RS structure has 8 antenna ports. Therefore, the maximum number of antenna ports used in this CSI-RS structure is 64.

[0073] Table 1 below shows the different N CDM,max , N f,max and Nt,max Possible CSI-RS configuration values

[0074] Table 1

[0075] Select a CSI-RS configuration from the set of configurations shown in Table 1 so that appropriate parameters can be used. N CDM,max , N f,max and N t,max Obtain the required number of CSI-RS antenna ports.

[0076] The actual port Np used by CSI-RS is selected based on the following possible port priorities (from...). N p,max Selected from: Implementation Plan 1: CDM Group first, FD-OCC Group second, TD-OCC Group third; In this implementation scheme, the function used to calculate port priority can be expressed as: ...Equation 4.

[0077] in It is a CDM group index. It is the FD-OCC code index in the CDM group. This is the TD-OCC code index in the CDM group. Equation 4 shows the indexing of the CDM group. FD-OCC code index in CDM group and the TD-OCC code index in the CDM group An example of a function to convert to port number p. This integer function specifies the port number of the signal based on the relevant parameters, and the range can be from 0 to... .

[0078] For subsequent implementations of this disclosure, the function from Equation 4 will take different forms.

[0079] Implementation Plan 2: FD-OCC first; CDM group second; TD-OCC third; Implementation Plan 3: FD-OCC first; TD-OCC second; CDM group third; Implementation Plan 4: TD-OCC first; FD-OCC second; CDM group third; Implementation Plan 5: CDM Group first; TD-OCC second; FD-OCC third; Implementation Scheme 6: Higher Layer / Downlink Control Information (DCI) Signaling Instructions One port.

[0080] Furthermore, this disclosure can use different CSI-RS modulation schemes with different waveforms. Flowcharts illustrating the CSI-RS modulation algorithm are shown in Figures 4A, 4B, and 4C.

[0081] Figure 4A is a flowchart of a CSI-RS modulation algorithm for xMIMO according to an embodiment of the present disclosure.

[0082] Referring to Figure 4A, firstly, a pseudo-random number generator generates a pseudo-random binary sequence based on initialization parameters (such as slot number, OFDM symbol number within the slot) and other parameters configurable by the Radio Resource Control (RRC) protocol. The generated binary sequence is modulated using QPSK symbols. After modulation, an OCC code obtained according to the process described herein is applied to the sequence. The resulting sequence is then modulated with CSI-RS resource elements. Here, as provided herein, a method for allocating resource elements in each CDM group is used. The result is fed into a CP-OFDM modulator. Next, discrete samples of the obtained CP-OFDM signal undergo digital-to-analog conversion (DAC). The signal then enters the RF path.

[0083] Figure 4B is a flowchart illustrating an alternative CSI-RS modulation algorithm according to an embodiment of the present disclosure.

[0084] Referring to Figure 4B, firstly, the pseudo-random number generator generates a pseudo-random binary sequence based on initialization parameters (such as slot number, OFDM symbol number within the slot) and other parameters configurable by the RRC protocol. The binary sequence is modulated using π / 2 binary phase shift keying symbols (π / 2-BPSK modulation). The resulting sequence is then DFT-expanded. After modulation, the OCC code obtained according to the process described herein is applied to the sequence. The resulting sequence is further modulated with CSI-RS resource elements. Here, as provided herein, the method used for allocating resource elements in each CDM group is used. The result is fed to the CP-OFDM modulator. Next, discrete samples of the obtained CP-OFDM signal are subjected to digital-to-analog conversion (DAC). The signal is then fed into the RF path. This algorithm guarantees a low PAPR.

[0085] Figure 4C is a flowchart illustrating another alternative CSI-RS modulation algorithm according to an embodiment of this disclosure.

[0086] Referring to Figure 4C, firstly, the generator generates a Zadoff-Chu sequence based on one or more initialization parameters (such as temporary slot numbers, OFDM symbol numbers in the slots) and other parameters configurable by the RRC protocol. The ZC sequence is then cyclically shifted. After the cyclic shift, the OCC code obtained according to the process described herein is applied to the sequence. The resulting sequence is further modulated with CSI-RS resource elements. As provided herein, the method used for allocating resource elements in each CDM group is employed. The result is fed into a CP-OFDM modulator. Next, discrete samples of the obtained CP-OFDM signal are subjected to digital-to-analog conversion (DAC). The signal then enters the RF path. This algorithm guarantees a low PAPR.

[0087] Therefore, this disclosure uses a uniform architecture to support various CSI-RS configurations with different numbers of antenna ports (up to 256) and different waveforms.

[0088] Figures 5A, 5B, and 5C illustrate the PRB distribution of CSI-RS according to various embodiments of this disclosure.

[0089] Referring to Figures 5A, 5B, and 5C, the distribution of CSI-RS across physical resource blocks (PRBs) in the prior art and according to this disclosure is shown.

[0090] Referring to Figure 5A, a typical cross-subband uniform PRB interleaving of a 5G NR system according to an embodiment of this disclosure is shown. In 5G NR, this PRB allocation for CSI-RS transmission is used to reduce overhead. Simultaneously, employing a cross-PRB distributed CSI-RS structure makes it more difficult to utilize channel coherence to improve the measurement of channel frequency characteristics.

[0091] Referring to Figure 5B, it illustrates a grouped PRB allocation for CSI-RS with a density of 0.5, optimized for subband structure, according to an embodiment of the present disclosure. In this example, the PRBs for CSI-RS are grouped at the center of the subband. According to the present disclosure, a given number is preferably used. PRB at intervals CSI-RS is transmitted in each subband, and The PRBs are continuous. Therefore, channel coherence can be used to improve channel estimation.

[0092] In most frequency-selective communication channels, the channel frequency characteristics are expected to vary slightly at subcarrier frequencies of adjacent PRBs compared to values ​​obtained at subcarrier frequencies separated by two or more PRBs. Therefore, at the receiver for a group of PRBs, after FD-OCC despreading (i.e., channel compression over the spectrum), the average channel frequency characteristic estimate will be less different from the actual frequency characteristics compared to a PRB with CSI-RS distributed across the entire subband. This makes channel estimation more accurate in the case of grouped PRBs.

[0093] The PRB block used for CSI-RS transmission is defined as: (5) in , , in, n It is the number of PRBs transmitted for CSI-RS. It constitutes the transmission of CSI-RS The number of PRBs in a repeating cycle of a consecutive PRB group. is the size of the group of consecutive PRBs transmitting CSI-RS (number of PRBs), n' is the PRB group index, and m' is the PRB index within the PRB group.

[0094] Therefore, PRB groups are separated by the same or similar distances in the frequency domain.

[0095] In one implementation, the period is equal to the number of PRBs in a subband: .

[0096] Number of PRBs used to transmit CSI-RS in each subband Configure via RRC protocol: = {1, 2, 3, 4, 5, 6, 7, all}.

[0097] Referring to Figure 5C, an alternative PRB allocation for CSI-RS with a density of 0.25, optimized for subband structure, is shown according to an embodiment of this disclosure. In the example shown, the PRBs for CSI-RS are also grouped at the center of the subband. Therefore, channel coherence can be used to improve channel estimation performance.

[0098] According to this disclosure, other PRB densities of CSI-RS can be used.

[0099] Therefore, by optimizing PRB allocation for CSI-RS subbands, this disclosure provides a more efficient overhead reduction for CSI-RS transmission. This overhead reduction is achieved, in particular, by the fact that a smaller number of PRB groups in the subband can be used for CSI-RS transmission compared to prior art CSI-RS with PRBs distributed across the entire subband, without sacrificing the estimation quality of channel frequency and timing characteristics.

[0100] Now for reference Figure 6 This describes the transmission of CSI-RS in the event of a conflict with the transmission of other reference signals, according to this disclosure.

[0101] In 5G NR, CSI-RS is transmitted continuously on adjacent OFDM symbols in a time slot (see [link]). Figure 6 (left side), and avoids conflicts between CSI-RS transmissions and other reference signal transmissions during the scheduling phase by selecting non-conflicting resources for transmission, i.e., the CDM group is continuous in the time domain.

[0102] However, in 6G systems, CSI-RS will obviously include a large number of OFDM symbols, making it difficult to schedule resources to avoid CSI-RS transmissions from interfering with other reference signals. Therefore, in one embodiment of this disclosure, a discontinuous time-domain CSI-RS structure is provided in the event of interference with other reference signals; that is, CDM groups are transmitted on non-adjacent OFDM symbols in time slots.

[0103] Figure 6 (Right side) shows a CSI-RS structure in the time domain in case of conflict with other reference signals in the prior art, according to an embodiment of this disclosure.

[0104] refer to Figure 6 This illustrates a CSI-RS structure where CSI-RS transmission conflicts with the transmission of other reference signals, such as the Tracking Reference Signal (TRS) or the Synchronization / Physical Broadcast Channel Signal (SS / PBCH). In this case, a gap is provided in the time domain of the CSI-RS structure for the transmission of other reference signals. This gap can be defined as follows: Implicitly, if a collision with other reference signals is detected, the transmission of CSI-RS symbols is delayed to allow the transmission of other reference signals. That is, if a collision occurs with other signals, the base station determines the actual OFDM symbol of the CSI-RS by delaying the transmission of all or part of the OFDM symbols of the CSI-RS to subsequent OFDM symbols (e.g., ...). Figure 6 On the right, the fifth and ninth OFDM symbols transmit TRS signals, and the base station delays CSI-RS transmission until subsequent OFDM symbols. -Displaying the OFDM symbol of the CDM group for transmitting CSI-RS when the base station is configured / indicated. At (for example, in) Figure 6 Middle, right side That is, signaling is used to indicate the actual OFDM symbol of CSI-RS in the UE.

[0105] Therefore, this disclosure provides a more flexible scheduling of reference signal transmission and allows different reference signals to be transmitted in the same time slot.

[0106] Figure 7 The CSI-RS transmission over two adjacent time slots in a 6G system according to an embodiment of this disclosure is illustrated.

[0107] Figure 8 The illustration shows CSI-RS transmissions via two sets of antenna ports in two different time slots in a 6G system according to an embodiment of this disclosure.

[0108] refer to Figure 7 and Figure 8 This disclosure describes options for CSI-RS transmission in multiple time slots according to the present disclosure.

[0109] 5G NR systems provide CSI-RS transmission in a single time slot.

[0110] However, due to the potential increase in the size of CSI-RS in 6G systems and the resulting complexity in transmitting it within a single time slot, embodiments of this disclosure utilize more than one (e.g., two) adjacent time slots (see [link]). Figure 7 The implementation provides CSI-RS transmission to increase the scheduling flexibility of CSI-RS transmission resources and other signals in the time domain. Therefore, the first and last CSI-RS symbols are in different time slots. This implementation also allows other signals to be transmitted in the same time slot as these "separate" CSI-RS signals.

[0111] For the same purpose, alternative embodiments of this disclosure provide the ability to divide antenna ports in a base station into two or more groups, wherein CSI-RS is transmitted to each of the antenna port groups in different time slots (see [link to documentation]). Figure 8 For example, ports with different polarizations can transmit signals in different time slots. This implementation provides more flexible transmission resource scheduling for CSI-RS and other signals in the time domain, and because the CSI-RS resource size in the time slot is smaller, other signals can be transmitted in the same time slot as CSI-RS.

[0112] Figure 9 The illustration schematically shows an embodiment of the present disclosure for use in accordance with... Figure 8The transmission implementation scheme shown uses two sets of antenna ports for CSI-RS transmission.

[0113] refer to Figure 9 A set of antenna ports ( Figure 9 The left side has one polarization, and the other set of antenna ports ( Figure 9 (Right side) has a second polarization. The polarization of the antenna port is... Figure 9 The diagram is schematically shown through two diagonal lines at each antenna port.

[0114] Due to the limited computing power of user equipment (UE) and the large number of antenna ports on the base station, in component carrier aggregation scenarios where data is transmitted on multiple component carriers, UE may be unable to calculate channel estimates from CSI-RS, as channel estimation is calculated for each component carrier. This leads to a situation where the base station must transmit multiple CSI-RS values ​​for different numbers of antenna ports to different users, depending on their computing capabilities. Figure 10 (Top). This significantly increases the CSI-RS transmission overhead of base stations in communication systems.

[0115] Figure 10 It is a CSI-RS structure according to an embodiment of this disclosure, which has resources shared for different numbers of antenna ports.

[0116] refer to Figure 10 According to this disclosure, CSI-RS resources with a smaller number of ports are proposed to be a subset of CSI-RS resources with a larger number of ports. This allows for the sharing of CSI-RS resources to transmit signals to multiple users, taking into account the computing power of multiple users (see [link to disclosure]). Figure 10 (Bottom). This reduces the CSI-RS transmission overhead at base stations in the communication system. Furthermore, users will be able to receive only their respective CSI-RS and estimate the channel.

[0117] In this disclosure, particularly in the resource-sharing implementation of this disclosure, the following CSI-RS port index p is proposed: according to the following equation, first across CDM groups, then according to the OCC code within the CDM group: Equation 6 in It is a CDM group index. It is the code index within the CDM group.

[0118] Figure 11 This is a schematic diagram illustrating the indexing of the antenna ports of the CSI-RS.

[0119] refer to Figure 11 It illustrates, according to the embodiments of this disclosure, forN CDM,max = 2、 N f,max = 4 and N t,max In the case of 8, the antenna ports of the CSI-RS structure in 5G NR are indexed (left) and (right). Therefore, according to Equation 3, the maximum number of antenna ports used for this CSI-RS structure is 64.

[0120] In this scenario, a 5G NR port with one polarization (port 0, 1, 2, ..., 31) transmits CSI-RS signals in one CDM group, and ports with other polarizations (port 32, 33, 34, ..., 63) transmit CSI-RS signals in a second CDM group.

[0121] If a user equipment only supports 32 ports, and therefore only receives one CDM group from the 64-port CSI-RS transmitted by the base station for channel estimation, then the user equipment receives signals from 32 single-polarization ports. Figure 12 (Left side).

[0122] Figure 12 This illustrates the basis for the embodiments according to this disclosure. Figure 11 A schematic diagram of the antenna port of CSI-RS, which transmits signals received by the user equipment.

[0123] refer to Figure 12 The base station ports from which a user equipment receives CSI-RS are schematically represented by solid diagonal lines. Ports from which a user equipment does not receive CSI-RS transmissions are schematically represented by dashed diagonal lines. The tilt of the diagonal lines schematically indicates the polarization of each port.

[0124] The port indexing process disclosed herein ( Figure 11 (Right side) This allows user equipment that only supports 32 ports to receive only one CDM group for channel estimation from the 64-port CSI-RS transmitted by the base station, but this CDM group corresponds to 32 ports with two polarizations ( Figure 12 (Right side).

[0125] CSI-RS transmission and precoding from cross-polarized antenna ports offer better performance than CSI-RS from co-polarized antenna ports. For example, using two polarizations allows transmission of two MIMO layers, thereby increasing the data transmission rate to the user equipment.

[0126] The CSI-RS generation method described herein and shown in Figures 4A, 4B, and 4C is used in communication systems to receive channel state information from user equipment via a network base station.

[0127] Figure 13 This is a flowchart illustrating a communication method in a communication system according to an embodiment of the present disclosure.

[0128] refer to Figure 13 The following describes an example of a method for communication in a communication system including at least one base station (BS) and at least one user equipment (UE), the method including the above-described process for obtaining channel state information. First, the base station detects and transmits configuration information with CSI-RS signal transmission parameters to the user equipment, which may include: - One or more code division multiplexing (CDM) groups, each CDM group having resource elements (REs) with a uniform frequency distribution (see [link to CDM group]). Figure 1 ); - Total number of ports, number of CDM groups, and OCC length calculated by time and frequency (see Table 1). -CSI-RS port index information (see Equation 6); - The CSI-RS waveforms used (see Figures 4A, 4B and 4C); Symbols used within a time slot ( Figure 6 (or delayed CSI-RS transmission); - CSI-RS transmission in one or two adjacent time slots (see...) Figure 7 ); -Transmission of port groups in different time slots (see...) Figure 8 and Figure 9 ); - There is a group of physical resource blocks (PRBs) in CSI-RS (see Figures 5A, 5B, and 5C and Equation 5). - and other information.

[0129] Then, the base station transmits a Channel State Information (CSI) request to the user equipment.

[0130] Next, the base station generates a CSI-RS signal for each antenna port of the base station (BS). This CSI-RS signal is modulated across resource elements in the frequency domain (FD) according to the Discrete Fourier Transform (DFT) vector using an orthogonal coverage code (OCC) (see Equation 1), and across one or more OFDM symbols in the time domain (TD) according to a Walsh-Hadamard code (WH) (see Equation 2). The base station then transmits the CSI-RS from the antenna ports defined by Equation 6 according to the indicated CSI-RS transmission configuration parameters.

[0131] The user equipment (UE) receives the CSI-RS reference signal based on the received CSI-RS configuration and measures channel characteristics from the base station's transmit port to obtain channel state information (CSI). Furthermore, this information is converted by the user into a set of indicators, such as the CSI-RS resource indicator (CRI), rank indicator (RI), precoding matrix indicator (PMI), and channel quality indicator (CQI), and transmitted to the base station via the feedback channel. After receiving the CSI channel state information from the UE, the base station accordingly selects the precoding space matrix, modulation scheme, and error correction coding rate for the Physical Downlink Shared Channel (PDSCH). The base station then generates a signal and transmits it in the PDSCH channel.

[0132] Therefore, this disclosure can increase the number of supported CSI-RS antenna ports to 256, supporting various waveforms with common structures (e.g., CP-OFDM) and low PAPR (e.g., OFDM with Discrete Fourier Transform Extended (DFT-s-OFDM, OFDM)). The CSI-RS structure exhibits optimized overhead reduction through subband structure. Furthermore, this disclosure provides more flexible CSI-RS transmission in different time slots and in the same time slot to match its transmission with other reference signals. In addition, the CSI-RS structure of this disclosure supports shared CSI-RS resources.

[0133] Figure 14 This is a block diagram of a terminal according to an embodiment of this disclosure.

[0134] refer to Figure 14 Terminal 1400 may include a processor 1410, a transceiver 1420, and a memory 1430. However, not all of the components shown are necessary. Terminal 1400 can be compared to... Figure 14 The components shown can be implemented with more or fewer components. Furthermore, according to another embodiment, the processor 1410, transceiver 1420, and memory 1430 can be implemented as a single chip.

[0135] Terminal 1400 can correspond to the UE mentioned above.

[0136] The above-mentioned components will now be described in detail.

[0137] Processor 1410 may include one or more processors or other processing devices that control the proposed functions, processes, and / or methods. Operation of terminal 1400 may be implemented by processor 1410.

[0138] Transceiver 1420 may include an RF transmitter for up-converting and amplifying the transmitted signal, and an RF receiver for down-converting the frequency of the received signal. However, according to another embodiment, transceiver 1420 may be implemented with more or fewer components than those shown in the components.

[0139] Transceiver 1420 can be connected to processor 1410 and transmit and / or receive signals. These signals may include control information and data. Furthermore, transceiver 1420 can receive signals via a wireless channel and output those signals to processor 1410. Transceiver 1420 can also transmit signals output from processor 1410 via a wireless channel.

[0140] Memory 1430 may store control information or data included in signals obtained by terminal 1400. Memory 1430 may be connected to processor 1410 and store at least one instruction or protocol or parameter for the proposed function, process, and / or method. Memory 1430 may include read-only memory (ROM) and / or random access memory (RAM) and / or hard disk and / or CD-ROM and / or DVD and / or other storage devices.

[0141] Figure 15 It is a base station according to the implementation scheme of this disclosure.

[0142] refer to Figure 15 Base station 1500 may include processor 1510, transceiver 1520, and memory 1530. However, not all of the components shown are necessary. Base station 1500 can be configured to... Figure 15 The components shown can be implemented with more or fewer components. Furthermore, according to another embodiment, the processor 1510, transceiver 1520, and memory 1530 can be implemented as a single chip.

[0143] The above-mentioned components will now be described in detail.

[0144] Processor 1510 may include one or more processors or other processing devices that control the proposed functions, processes, and / or methods. Operation of base station 1500 may be implemented by processor 1510.

[0145] Transceiver 1520 may include an RF transmitter for up-converting and amplifying the transmitted signal, and an RF receiver for down-converting the frequency of the received signal. However, according to another embodiment, transceiver 1520 may be implemented with more or fewer components than those shown in the components.

[0146] Transceiver 1520 can be connected to processor 1510 and transmit and / or receive signals. These signals may include control information and data. Furthermore, transceiver 1520 can receive signals via a wireless channel and output those signals to processor 1510. Transceiver 1520 can also transmit signals output from processor 1510 via a wireless channel.

[0147] Memory 1530 may store control information or data included in signals obtained by base station 1500. Memory 1530 may be connected to processor 1510 and store at least one instruction, protocol, or parameter for the proposed function, process, and / or method. Memory 1530 may include read-only memory (ROM) and / or random access memory (RAM) and / or hard disk and / or CD-ROM and / or DVD and / or other storage devices.

[0148] Although this disclosure has been described with reference to exemplary embodiments, various changes and modifications can be made by those skilled in the art. This disclosure is intended to cover such changes and modifications that fall within the scope of the appended claims.

[0149] Another aspect of this disclosure provides a base station configured to: set CSI-RS transmission configuration information, the CSI-RS transmission configuration information including one or more CDM groups, each CDM group having resource elements (REs) with a uniform frequency distribution; transmit the CSI-RS transmission configuration information to a user equipment (UE); generate a CSI-RS signal for each antenna port of the base station, the CSI-RS signal being modulated across resource elements in the frequency domain (FD) according to a discrete Fourier transform (DFT) vector via OCC, and modulated across one or more OFDM symbols in the time domain (TD) according to a Walsh-Hadamard (WH) code; and transmit the CSI-RS to the UE according to the CSI-RS transmission configuration.

[0150] Another aspect of this disclosure provides a computer-readable medium including a program that, when executed by at least one processor, causes at least one processor to perform the above-described method for transmitting CSI-RS according to this disclosure.

[0151] According to embodiments of this disclosure, the user equipment (UE) described herein may be a terminal, a mobile station (MS), an advanced mobile station (AMS), etc. Furthermore, a base station (BS) is a generic name for a network architecture node used to communicate with the user equipment, such as a node B (NB), eNode B (eNB), access point (AP), gNode B, etc.

[0152] The above description applies to various wireless communication systems, including Code Division Multiple Access (CDMA), Frequency Division Multiple Access (FDMA), Time Division Multiple Access (TDMA), Orthogonal Frequency Division Multiple Access (TDMA), and Single-Carrier Frequency Division Multiple Access (SC-FDMA). OFDMA can be implemented using wireless architectures such as IEEE 802.11 (Wi-Fi), IEEE 802.16 (Global Microwave Access Interoperability (WiMAX)), IEEE 802.20, and Evolved Universal Terrestrial Radio Access Network (E-UTRA), which is part of the Universal Mobile Telecommunications System (UMTS). 3GPP Long Term Evolution (LTE) is part of Evolved UMTS (E-UMTS) using E-UTRA. 3GPP LTE uses OFDMA in DL and SC-FDMA in UL, and LTE-A Advanced is an advanced version of 3GPP LTE. CDMA can be implemented using wireless architectures such as Universal Terrestrial Access (UTRA) and CDMA 2000. TDMA can be implemented using wireless architectures such as GSM / GPRS / EDGE (Global System for Mobile Communications) / General Packet Radio / Enhanced Data Rate GSM Evolution.

[0153] Each of the base station and user equipment disclosed herein supports a multiple-input multiple-output (MIMO) system. The base station of this disclosure can support single-user MIMO (SU-MIMO) and multi-user MIMO (MU-MIMO) systems.

[0154] It should be understood that while terms such as “first,” “second,” “third,” etc., may be used herein to describe various elements, components, regions, layers, and / or parts, these elements, components, regions, layers, and / or parts should not be limited to these terms. These terms are used only to distinguish one element, component, region, layer, or part from another. Thus, a first element, component, region, layer, or part may be referred to as a second element, component, region, layer, or part without departing from the scope of this disclosure. As used herein, the term “and / or” includes any and all combinations of one or more of the associated listed items.

[0155] The function of an element specified as a single element in the specification or claims can be implemented in practice by multiple parts of the device, and conversely, the function of an element specified as several separate elements in the specification or claims can be implemented in practice by a single element.

[0156] The embodiments disclosed herein are not limited to those described herein. Other embodiments of this disclosure, without departing from the spirit and scope thereof, will be readily apparent to those skilled in the art based on the information provided in the specification and relevant field knowledge.

[0157] Those skilled in the art will understand that the ideas of this disclosure are not limited to specific software or hardware implementations, and therefore any software and hardware known in the art can be used to implement this disclosure. Accordingly, the hardware can be implemented in one or more application-specific integrated circuits, digital signal processors, digital signal processing devices, programmable logic devices, field-programmable gate arrays, processors, controllers, microcontrollers, microprocessors, electronic devices, other electronic modules configured to perform the functions described herein, computers, or combinations thereof.

[0158] Clearly, referring to the storage of data, programs, etc., implies providing a computer-readable data medium. Examples of computer-readable storage media include read-only memory, random access memory, registers, cache memory, solid-state storage devices, magnetic media such as internal hard disk drives and removable disks, magneto-optical and optical media such as optical disc read-only memory (CD-ROM) and digital versatile optical disc (DVD), and any other data media known in the art.

[0159] It will be understood that various embodiments of the present disclosure as described in the claims and specification can be implemented in hardware, software, or a combination of hardware and software.

[0160] Any such software can be stored in a non-transitory computer-readable storage medium. The non-transitory computer-readable storage medium stores one or more computer programs (software modules), the one or more computer programs including computer-executable instructions that, when executed by one or more processors of an electronic device, cause the electronic device to perform the methods of this disclosure.

[0161] Any such software may be stored in the form of volatile or non-volatile memory, such as, for example, a storage device such as read-only memory (ROM) (whether erasable or rewritable); or in the form of memory, such as, for example, random access memory (RAM), memory chips, devices, or integrated circuits; or stored on an optical or magnetically readable medium, such as, for example, an optical disc (CD), a digital versatile optical disc (DVD), a magnetic disk, or magnetic tape. It will be understood that storage devices and storage media are various embodiments of non-transitory machine-readable memory suitable for storing one or more computational programs comprising instructions that, when executed, implement various embodiments of this disclosure. Therefore, various embodiments provide a program comprising code for implementing the means or methods as described in any one of the claims of this specification, and a non-transitory machine-readable memory storing such a program.

[0162] Although this disclosure has been shown and described with reference to various embodiments thereof, those skilled in the art will understand that various changes in form and detail may be made therein without departing from the spirit and scope of this disclosure as defined by the appended claims and their equivalents.

Claims

1. A method performed by a base station in a wireless communication system, the method comprising: The Channel State Information Reference Signal (CSI-RS) transmission configuration information is transmitted to the terminal. The CSI-RS transmission configuration information includes one or more Code Division Multiplexing (CDM) groups, and the resource elements (REs) in each CDM group have a uniform frequency distribution. The terminal is transmitted with CSI-RS generated for each antenna port of the base station based on the CSI-RS transmission configuration, wherein the CSI-RS is modulated across resource elements in the frequency domain (FD) using orthogonal coverage code (OCC) and across one or more orthogonal frequency division multiplexing (OFDM) symbols using Walsh-Hadamard (WH) code; and Receive channel state information based on the CSI-RS from the terminal.

2. The method according to claim 1, The CSI-RS transmission configuration information further includes at least one of the following: information about the number of ports, information about the number of CDM groups, the length of the OCC in time and frequency, CSI-RS port index information, CSI-RS waveform, OFDM symbols and time slots for the CSI-RS, or the existence of physical resource blocks (PRBs) for CSI-RS. in, The PRB group comprises two or more adjacent PRBs, which are spaced at the same or similar distances from each other in the frequency domain. The antenna ports used for CSI-RS are indexed in the following order: first across CDM groups, then by OCC within the CDM group.

3. The method according to claim 1, in, The CSI-RS is generated by modulating a CSI-RS sequence using one of the following: quadrature phase shift keying (QPSK) symbols, p / 2 binary phase shift keying (p / 2-BPSK) symbols, or a Zadoff-Chu ZC sequence. The QPSK symbols and p / 2-BPSK symbols are obtained based on pseudo-random sequences. CDM groups are transmitted on non-adjacent OFDM symbols within a time slot. In the event that the CSI-RS conflicts with another signal, the actual OFDM symbol used for the CSI-RS is determined by delaying the subsequent transmission of all or part of the OFDM symbols used for the CSI-RS to the next OFDM symbol. Information relating to the actual OFDM symbols used for CSI-RS is indicated to the terminal, and The other signal includes the tracking reference signal TRS.

4. The method according to claim 1, in, The first and last symbols of the CSI-RS are in different time slots. Specifically, a first subset of the CSI-RS ports is transmitted in the first time slot, and a second subset of the CSI-RS ports is transmitted in the second time slot. Wherein, the polarization of the first subset of the CSI-RS ports differs from the polarization of the second subset of the CSI-RS ports, and The first CSI-RS, corresponding to a smaller number of antenna ports, is a subset of the second CSI-RS, corresponding to a larger number of antenna ports.

5. A method performed by a terminal in a wireless communication system, the method comprising: The channel state information reference signal (CSI-RS) is received from the base station to transmit configuration information, which includes one or more code division multiplexing (CDM) groups, and the resource elements (REs) in each CDM group have a uniform frequency distribution. The base station receives CSI-RS based on the CSI-RS transmission configuration, wherein the CSI-RS is modulated across resource elements in the frequency domain FD based on Discrete Fourier Transform (DFT) vectors using orthogonal coverage code (OCC), and across one or more orthogonal frequency division multiplexing (OFDM) symbols in the time domain TD based on Walsh-Hadamard (WH) codes. as well as The base station transmits channel state information based on measurements of the CSI-RS.

6. The method according to claim 5, The CSI-RS transmission configuration information further includes at least one of the following: information about the number of ports, information about the number of CDM groups, the length of the OCC in time and frequency, CSI-RS port index information, CSI-RS waveform, OFDM symbols and time slots for the CSI-RS, or the existence of physical resource blocks (PRBs) for CSI-RS. in, The PRB group comprises two or more adjacent PRBs, which are spaced at the same or similar distances from each other in the frequency domain. The antenna ports used for CSI-RS are indexed in the following order: first across CDM groups, then by OCC within the CDM group.

7. The method according to claim 5, in, The CSI-RS is based on the modulation of the CSI-RS sequence using one of the following: quadrature phase shift keying (QPSK) symbols, p / 2 binary phase shift keying (p / 2-BPSK) symbols, or the Zadoff-Chu ZC sequence. The QPSK symbols and p / 2-BPSK symbols are obtained based on pseudo-random sequences. In this context, the CDM group receives data on non-adjacent OFDM symbols within the time slot. In the event that the CSI-RS conflicts with another signal, the actual OFDM symbol used for the CSI-RS is determined by delaying the subsequent transmission of all or part of the OFDM symbols used for the CSI-RS to the next OFDM symbol. Information relating to the actual OFDM symbols used for CSI-RS is indicated to the terminal, and The other signal includes the tracking reference signal TRS.

8. The method according to claim 5, in, The first and last symbols of the CSI-RS are in different time slots. Specifically, a first subset of the CSI-RS ports is received in the first time slot, and a second subset of the CSI-RS ports is transmitted in the second time slot. Wherein, the polarization of the first subset of the CSI-RS ports differs from the polarization of the second subset of the CSI-RS ports, and The first CSI-RS, corresponding to a smaller number of antenna ports, is a subset of the second CSI-RS, corresponding to a larger number of antenna ports.

9. A base station in a wireless communication system, the base station comprising: transceiver; as well as The controller is configured as follows: The transceiver is controlled to transmit Channel State Information Reference Signal (CSI-RS) transmission configuration information to the terminal. The CSI-RS transmission configuration information includes one or more Code Division Multiplexing (CDM) groups, and the resource elements (REs) in each CDM group have a uniform frequency distribution. The transceiver is controlled to transmit to the terminal a CSI-RS generated for each antenna port of the base station based on the CSI-RS transmission configuration. The CSI-RS is modulated across resource elements in the frequency domain (FD) based on the Discrete Fourier Transform (DFT) vector using orthogonal coverage code (OCC) and across one or more orthogonal frequency division multiplexing (OFDM) symbols in the time domain (TD) based on Walsh-Hadamard (WH) code. as well as Control the transceiver to receive channel state information based on the CSI-RS from the terminal.

10. The base station according to claim 9, The CSI-RS transmission configuration information further includes at least one of the following: information about the number of ports, information about the number of CDM groups, the length of the OCC in time and frequency, CSI-RS port index information, CSI-RS waveform, OFDM symbols and time slots for the CSI-RS, or the existence of physical resource blocks (PRBs) for CSI-RS. in, The PRB group comprises two or more adjacent PRBs, which are spaced at the same or similar distances from each other in the frequency domain. The antenna ports used for CSI-RS are indexed in the following order: first across CDM groups, then by OCC within the CDM group.

11. The base station according to claim 9, in, The CSI-RS is generated by modulating a CSI-RS sequence using one of the following: quadrature phase shift keying (QPSK) symbols, p / 2 binary phase shift keying (p / 2-BPSK) symbols, or a Zadoff-Chu ZC sequence. The QPSK symbols and p / 2-BPSK symbols are obtained based on pseudo-random sequences. CDM groups are transmitted on non-adjacent OFDM symbols within a time slot. In the event that the CSI-RS conflicts with another signal, the actual OFDM symbol used for the CSI-RS is determined by delaying the subsequent transmission of all or part of the OFDM symbols used for the CSI-RS to the next OFDM symbol. Information relating to the actual OFDM symbols used for CSI-RS is indicated to the terminal, and The other signal includes the tracking reference signal TRS.

12. The base station according to claim 9, in, The first and last symbols of the CSI-RS are in different time slots. Specifically, a first subset of the CSI-RS ports is transmitted in the first time slot, and a second subset of the CSI-RS ports is transmitted in the second time slot. Wherein, the polarization of the first subset of the CSI-RS ports differs from the polarization of the second subset of the CSI-RS ports, and The first CSI-RS, corresponding to a smaller number of antenna ports, is a subset of the second CSI-RS, corresponding to a larger number of antenna ports.

13. A terminal in a wireless communication system, the terminal comprising: transceiver; as well as The controller is configured as follows: The transceiver is controlled to receive Channel State Information Reference Signal (CSI-RS) transmission configuration information from the base station. The CSI-RS transmission configuration information includes one or more Code Division Multiplexing (CDM) groups, and the resource elements (REs) in each CDM group have a uniform frequency distribution. The transceiver is controlled to receive CSI-RS based on the CSI-RS transmission configuration from the base station, wherein the CSI-RS is modulated across resource elements in the frequency domain FD based on the Discrete Fourier Transform (DFT) vector using orthogonal coverage code OCC, and across one or more orthogonal frequency division multiplexing (OFDM) symbols in the time domain TD based on Walsh-Hadamard (WH) code. as well as The transceiver is controlled to transmit channel state information based on measurements of the CSI-RS to the base station.

14. The terminal according to claim 13, The CSI-RS transmission configuration information further includes at least one of the following: information about the number of ports, information about the number of CDM groups, the length of the OCC in time and frequency, CSI-RS port index information, CSI-RS waveform, OFDM symbols and time slots for the CSI-RS, or the existence of physical resource blocks (PRBs) for CSI-RS. in, The PRB group comprises two or more adjacent PRBs, which are spaced at the same or similar distances from each other in the frequency domain. The antenna ports used for CSI-RS are indexed in the following order: first across CDM groups, then by OCC within the CDM group.

15. The terminal according to claim 13, in, The CSI-RS is based on the modulation of the CSI-RS sequence using one of the following: quadrature phase shift keying (QPSK) symbols, p / 2 binary phase shift keying (p / 2-BPSK) symbols, or the Zadoff-Chu ZC sequence. The QPSK symbols and p / 2-BPSK symbols are obtained based on pseudo-random sequences. In this context, the CDM group receives data on non-adjacent OFDM symbols within the time slot. In the event that the CSI-RS conflicts with another signal, the actual OFDM symbol used for the CSI-RS is determined by delaying the subsequent transmission of all or part of the OFDM symbols used for the CSI-RS to the next OFDM symbol. Information relating to the actual OFDM symbols used for CSI-RS is indicated to the terminal, and The other signal includes the tracking reference signal TRS.

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