Hierarchical Channel State Information (CSI) Feedback with Partial Reciprocity in the Network

Abstract

Base stations or other network components (next-generation node B (gNB)) can operate to transmit a channel state information reference signal (CSI-RS) for channel state information (CSI) feedback. In response to the provision of CSI-RS, the CSI feedback is received as one or more frequency portions corresponding to the hierarchical precoding level in the frequency band, based on a hierarchical precoding scheme.

Description

[0001] Citation of relevant applications

[0002] This application was filed on August 7, 2020, and is entitled "HEIRARCHICAL CHANNEL STATE". Information (CSI) Feedback with Partial Reciprocity in a Network The international patent application PCT / CN2020 / 107926, concerning graded channel state information (CSI) feedback based on reciprocity, has been entered into a national patent application process. The application is for this stage, the contents of which are incorporated herein by reference in their entirety. Technical Field

[0003] This disclosure relates to wireless technologies, and more specifically, to techniques for hierarchical channel state information (CSI) feedback for user equipment (UE) with partial reciprocity. Background Technology

[0004] The explosive growth of wireless traffic has created an urgent need for increased speeds. Further improvements in spectral efficiency, leveraging mature physical layer technologies, may be negligible. On the other hand, the scarcity of licensed spectrum in low-frequency bands limits data rate increases. The next-generation wireless communication system, 5G, will provide information access and data sharing anytime, anywhere for a wide range of users and applications. 5G promises to be a unified network / system designed to meet diverse and sometimes conflicting performance dimensions and services. These diverse, multidimensional needs are driven by different services and applications. Generally, 5G can evolve based on 3GPP Advanced Long Term Evolution (LTE) (LTE-Advanced) with the potential addition of New Radio Access Technologies (RATs), enriching people's lives with better, simpler, and seamless wireless connectivity solutions. 5G will enable many devices to connect wirelessly and provide fast, rich content and services.

[0005] Similar to LTE, multi-antenna technology can be a key technical component in 3GPP 5G New Radio (NR) systems. Specifically, beamforming with very narrow beamwidths (resulting in high beamforming gain) can be an important tool for achieving targeted coverage in high-frequency NR. For example, to operate over a wide frequency range from below 6 GHz to 100 GHz, 3GPP NR aims to provide a unified approach to single-beam and multi-beam transmission. Multiple antennas can also be implemented at transmission equipment such as transmit-receive points (TRPs) (e.g., eNodeB (eNB) / next-generation nodeB (gNB) / base station antenna panels) and user equipment (UEs), and are referred to as multiple-input multiple-output (MIMO) devices. MIMO technology uses multiple antennas or antenna arrays / panels at one or more transmitters (Tx) and one or more receivers (Rx). MIMO systems can be used to increase network data throughput and link reliability without increasing bandwidth frequency or network transmission power. To achieve this, data communication between nodes (eNB / gNB) and mobile devices (e.g., UEs) can be distributed across multiple antennas to improve spectral efficiency and achieve array gain for diversity. Massive MIMO allows for the deployment of a large number of antenna elements in the antenna array. Multiple terminals can be deployed to combine massive MIMO technology with conventional time-division and frequency-division multiplexing using orthogonal frequency-division multiplexing (OFDM).

[0006] Three-dimensional (3D) or full-dimensional (FD) MIMO systems can be used in MIMO networks to enhance cellular performance by deploying antenna elements (e.g., two-dimensional (2D) antenna arrays) in both the horizontal and vertical dimensions. FD MIMO systems can direct two-dimensional (i.e., horizontal and vertical) communication to locations in three-dimensional (3D) space. Compared to traditional two-dimensional MIMO systems, the directionality of communication in 3D space can be improved, allowing for an increased number of communication paths, more focused beamforming, and increased throughput for spatial multiplexing. Attached Figure Description

[0007] Figure 1 This is a block diagram illustrating an example of a user equipment (UE) that can be used in conjunction with the various aspects described herein, the UE being communicatively coupled via a network to a network component that is a peer device.

[0008] Figure 2 This is an exemplary simplified block diagram of a user equipment (UE) wireless communication device or other network device / component (e.g., eNB, gNB) based on various aspects.

[0009] Figure 3 This is a diagram illustrating an exemplary precoding hierarchy structure for a hierarchical precoding scheme, based on various aspects.

[0010] Figure 4 This is a diagram of another exemplary precoding hierarchy structure for a hierarchical precoding scheme, based on various aspects.

[0011] Figure 5 This is a diagram of another exemplary precoding hierarchy structure for a hierarchical precoding scheme, based on various aspects.

[0012] Figure 6 This is another block diagram illustrating an exemplary processing flow for hierarchical precoding based on various aspects.

[0013] Figure 7 This is another block diagram illustrating an exemplary processing flow for hierarchical precoding based on various aspects. Detailed Implementation

[0014] As is widely recognized, the use of personally identifiable information should comply with privacy policies and practices that are generally accepted to meet or exceed industry or governmental requirements for protecting user privacy. Specifically, personally identifiable information data should be managed and processed to minimize the risk of unintentional or unauthorized access or use, and the nature of authorized use should be clearly explained to users.

[0015] This disclosure will now be described with reference to the accompanying drawings, wherein similar (or similarly ending) reference numerals are used throughout to denote similar elements, and the structures and devices shown therein are not necessarily drawn to scale. As used herein, the terms “component,” “system,” “interface,” etc., are intended to refer to entities, hardware, software (e.g., in execution), and / or firmware related to a computer. For example, a component can be a processor (e.g., a microprocessor, controller, or other processing device), a process running on a processor, a controller, an object, an executable file, a program, a storage device, a computer, a tablet computer, and / or user equipment with processing devices (e.g., a mobile phone, etc.). By way of example, an application running on a server and a server can also be components. One or more components may reside in a process, and components may be located on a single computer and / or distributed across two or more computers. This document may describe a set of elements or other sets of components, wherein the term “set” can be interpreted as “one or more.”

[0016] Furthermore, these components can be executed from various computer-readable storage media on which various data structures are stored, such as by utilizing modules, for example. Components can communicate via local and / or remote processes, for example, based on signals having one or more data packets (e.g., data from one component interacts with another component in a local system, a distributed system, and / or throughout a network, such as the Internet, a local area network, a wide area network, or similar networks with other systems via signals).

[0017] For example, a component can be a device with a specific function provided by a mechanical component operated by electrical or electronic circuitry, wherein the electrical or electronic circuitry can be operated by a software application or firmware application executed by one or more processors. The one or more processors can be internal or external to the device and can execute at least a portion of the software or firmware application. As another example, a component can be a device that provides a specific function through an electronic component without a mechanical component; the electronic component may include one or more processors to execute software and / or firmware that at least partially endows the electronic component with that function.

[0018] The use of the term “exemplary” is intended to present the concept in a specific manner. As used herein, the term “or” is intended to mean an inclusive “or” rather than an exclusive “or.” That is, unless otherwise stated or clearly apparent from the context, “X adopts A or B” is intended to mean any natural inclusive arrangement. That is, “X adopts A or B” is satisfied if X adopts A; X adopts B; or X adopts both A and B. Additionally, the articles “a” and “an” used in this application and the appended claims should generally be interpreted as meaning “one or more” unless otherwise stated or clearly apparent from the context to refer to the singular form. Furthermore, to the extent that the terms “comprising,” “including,” “having,” “having,” “with,” or variations thereof are used in the Detailed Description and Claims, such terms are intended to be included in a manner similar to the term “comprising.” Furthermore, in the context of discussing one or more numbered items (e.g., “first X,” “second X,” etc.), generally, the one or more numbered items may be different or they may be the same, but in some cases, the context may indicate that they are different or that they are the same.

[0019] As used herein, the term "circuit" may refer to, be part of, or may include: an application-specific integrated circuit (ASIC), electronic circuit, processor (shared, dedicated, or grouped), or associated memory (shared, dedicated, or grouped) operatively coupled to the circuit, which executes one or more software or firmware programs, combinational logic circuitry, or other suitable hardware components that provide the described functionality. In some embodiments, the circuit may be implemented in one or more software or firmware modules, or the functionality associated with the circuit may be implemented by one or more software or firmware modules. In some embodiments, the circuit may include logic that is at least partially operable in hardware.

[0020] In light of the above, various aspects / implementations for communication in beamforming systems or beamforming network equipment (e.g., User Equipment (UE), Evolved Node B (eNB), Next Generation Node B (gNB), New Radio (NR) Base Station (BS), Multiple-Input Multiple-Output (MIMO) equipment, Single-Input Multiple-Output (SIMO) equipment, etc.) are disclosed. Specifically, performance-related issues (power efficiency, beamforming, channel quality, etc.) may arise during beam management relative to LTE Advanced and 5G NR equipment, including CSI reporting, which can improve the Channel State Information (CSI) observed by the receiver (Rx) regarding the downlink channel. For example, for MU-MIMO pairing, wideband precoding may result in significant throughput loss at cell edges and for median UEs compared to subband precoding. For example, although the precoding scheme used for the Physical Downlink Shared Channel (PDSCH) is not always exactly wideband, a composite precoder can be frequency-selective, assuming the same frequency-selective precoder used for Channel State Information-Reference Signal (CSI-RS) is used together with a wideband precoder, as recommended by the UE, for PDSCH transmission. However, while wideband PMI feedback works well with specific gNB precoding schemes used for CSI-RS, it may not work well with other gNB precoding schemes, particularly for full division duplex (FDD) operation with partial reciprocity and for time division duplex (TDD) operation. Therefore, improving the precoding performance of UEs with network gNBs, for example by reducing overhead or feedback overhead while ensuring the gNB accurately obtains channel or subband spacing information, is a priority.

[0021] CSI can be obtained from Rx via either the transmit side (Tx) or the network side: a) based on the uplink channel estimate and through the channel reciprocity of the radio channel; and b) derived from the quantized feedback measured by Rx. The quantized form of the CSI feedback can be used for both FDD and TDD operating systems. The quantized CSI (or CSI) includes a precoding matrix index (PMI) to assist in beamforming or precoding selection on the gNB's Tx antenna. The set (or group) of possible PMIs is represented as a codebook. For different possible deployments of the 5G New Radio (NR) system, codebooks are designed and configured to provide reasonable performance in all possible service directions of the gNB. However, depending on the actual deployment of the gNB, the use of some PMIs in such codebooks can be avoided. For example, some PMI vectors may cause higher interference in the downlink (DL) channel compared to others, considering the potential interference to neighboring cells. To avoid CSI reporting with large feedback overhead, specifically, a hierarchical precoding scheme can be configured and used by the UE for CSI feedback, taking beamforming into account.

[0022] On one hand, the UE can configure CSI feedback according to a hierarchical precoding scheme to selectively reduce the feedback overhead associated with the CSI feedback. Specifically, the UE can configure a precoding hierarchy for hierarchical frequency-selective precoding to provide precoders for CSI feedback associated with hierarchical precoding levels of the precoding hierarchy. This can selectively reduce feedback overhead by allowing the UE to trim precoders belonging to subbands of frequency portions at hierarchical levels. As generally referred to herein, a subband can be a portion of a frequency portion divided according to a frequency band at the lowest hierarchical precoding level of the precoding hierarchy, where, for example, these subbands are at the highest index level. A frequency portion may be referred to herein as a partitioned portion of a frequency band that is not at the lowest level of the precoding hierarchy. However, the terms "frequency portion" and "subband" are used interchangeably.

[0023] Other aspects and details of this disclosure are further described below with respect to the accompanying drawings.

[0024] Figure 1 An exemplary architecture of system 100 for a network according to various implementations (aspects) is illustrated. The following description is provided for an example system 100 operating in combination with LTE system standards and 5G or NR system standards provided by 3GPP technical specifications. However, the exemplary implementation is not limited in this respect, and the implementation can be applied to other networks that benefit from the principles described herein, such as future 3GPP systems (e.g., sixth generation (6G)) systems, IEEE 802.16 protocols (e.g., WMAN, WiMAX, etc.), etc.

[0025] like Figure 1 As shown, system 100 includes UE 101a and UE 101b (collectively referred to as "UE101"). In this example, UE101 is shown as a smartphone (e.g., a handheld touchscreen mobile computing device that can connect to one or more cellular networks), but may include any mobile or non-mobile computing device, such as consumer electronics devices, cellular phones, smartphones, feature phones, tablets, wearable computing devices, personal digital assistants (PDAs), pagers, wireless handheld devices, desktop computers, laptops, in-vehicle infotainment (IVI), in-vehicle entertainment (ICE) devices, instrument cluster (IC), head-up display (HUD) devices, on-board diagnostic (OBD) devices, dashtop mobile equipment (DME), mobile data terminal (MDT), electronic engine management system (EEMS), electronic / engine control unit (ECU), electronic / engine electronic control module (ECM), embedded systems, microcontrollers, control modules, engine management system (EMS), connected or "smart" appliances, machine-type communication (MTC) devices, machine-to-machine (M2M) devices, Internet of Things (IoT) devices, etc.

[0026] In some implementations, any of UEs 101 can be an IoT UE, which may include a network access layer designed to utilize low-power IoT applications with short-lived UE connections. The IoT UE may utilize technologies such as M2M or MTC to exchange data with an MTC server or device via a Public Land Mobile Network (PLMN), Proximity Service (ProSe), or Device-to-Device (D2D) communication, sensor network, or IoT network. M2M or MTC data exchange may be machine-initiated data exchange. The IoT network describes interconnected IoT UEs, which may include uniquely identifiable embedded computing devices (within the Internet infrastructure) with short-lived connections. The IoT UE may execute background applications (e.g., keeping track of activity messages, status updates, etc.) to facilitate connectivity within the IoT network.

[0027] UE 101 can be configured to connect to or, for example, be communicatively coupled to a radio access network (RAN) 110. In implementations, RAN 110 can be a next-generation (NG) RAN or a 5G RAN, an evolved-UMTS terrestrial RAN (E-UTRAN), or a legacy RAN such as a UTRAN or GERAN. As used herein, the term "NG RAN," etc., can refer to RAN 110 operating in an NR or 5G system 100, while the term "E-UTRAN," etc., can refer to RAN 110 operating in an LTE or 4G system 100. UE 101 utilizes connections (or channels) 102 and 104, each connection (or channel) including a physical communication interface / layer.

[0028] Alternatively or otherwise, each UE in UE 101 may be configured with dual connectivity (DC) as multiple RATs or multiple radio dual connectivity (MR-DC), wherein a UE with multiple Rx / Tx capabilities may be configured to utilize resources provided by two different nodes (e.g., 111, 112, or other network nodes) capable of connecting via non-ideal backhaul connections, for example, one node providing NR access and the other providing E-UTRA for LTE or NR access for 5G. One node may act as a primary node (MN), and the other node may act as a secondary node (SN). The MN and SN may be connected via a network interface, and at least the MN may be connected to the core network 120. At least one of the MN and / or SN may operate using shared spectrum channel access. All functions specified for the UE may be available for Integrated Access and Backhaul Mobile Terminal (IAB-MT). Similar to UE 101, the IAB-MT may use one network node or two different nodes with EN-DC architecture, NR-DC architecture, etc., to access the network.

[0029] The diagram shows UE 101b configured to access AP 106 (also referred to as "WLAN node 106", "WLAN 106", "WLAN terminal 106", "WT 106", etc.) via connection 107. Connection 107 may include a local wireless connection, such as a connection consistent with any IEEE 802.11 protocol, where AP 106 will include Wireless Fibre. Router. In this example, AP106 is shown connected to the Internet but not to the core network of the wireless system (described in further detail below). In various implementations, UE 101b, RAN 110, and AP 106 can be configured to utilize LTE-WLAN aggregation (LWA) operation and / or LTE / WLAN radio-level operation integrated with IPsec tunneling (LWIP). LWA operation may involve RAN nodes 111a-111b configuring UE 101b, which is in the Radio Resource Control (RRC_CONNECTED) state, to utilize the radio resources of LTE and WLAN. LWIP operation may involve UE 101b using WLAN radio resources (e.g., connection 107) via IPsec protocol tunneling to authenticate and encrypt packets (e.g., IP packets) transmitted through connection 107. IPsec tunneling may include encapsulating the entire original IP packet and adding a new packet header to protect the original header of the IP packet.

[0030] RAN 110 may include one or more access nodes (ANs) or RAN nodes 111a and 111b (collectively or separately referred to as "RAN node 111" or "RAN 111") that enable connections between 102 and 104. As used herein, the terms "access node," "access point," etc., can describe equipment that provides radio baseband functionality for data and / or voice connections between the network and one or more users. These access nodes may be referred to as BS, gNB, RAN node, eNB, node B, RSU, transmit-receive point (TRxP), or TRP, etc., and may include ground stations (e.g., terrestrial access points) or satellite stations that provide coverage within a geographic area (e.g., a cell). As used herein, the terms "NG RAN node," etc., can refer to RAN node 111 (e.g., gNB) operating in NR or 5G system 100, and the terms "E-UT RAN node," etc., can refer to RAN node 111 (e.g., eNB) operating in LTE or 4G system 100. According to various implementation schemes, RAN node 111 may be implemented as one or more of dedicated physical devices such as macro cell base stations and / or low-power (LP) base stations, which are used to provide femtocell base stations, picocell base stations or other similar cells with smaller coverage area, smaller user capacity or higher bandwidth compared to macro cells.

[0031] In some implementations, all or part of the multiple RAN nodes 111 may be implemented as one or more software entities running on a server computer as part of a virtual network, which may be referred to as a Centralized RAN (CRAN) and / or a Virtual Baseband Unit Pool (vBBUP). In these implementations, the CRAN or vBBUP may implement RAN function splitting, such as Packet Data Convergence Protocol (PDCP) splitting, where the Radio Resource Control (RRC) layer and PDCP layer are operated by the CRAN / vBBUP, and other L2 protocol entities are operated by the individual RAN nodes 111; Media Access Control (MAC) / Physical (PHY) layer splitting, where the RRC layer, PDCP layer, RLC layer, and MAC layer are operated by the CRAN / vBBUP, and the PHY layer is operated by the individual RAN nodes 111; or “lower PHY” splitting, where the upper part of the RRC layer, PDCP layer, RLC layer, MAC layer, and PHY layer is operated by the CRAN / vBBUP, and the lower part of the PHY layer is operated by the individual RAN nodes 111. This virtualization framework allows the idle processor cores of the multiple RAN nodes 111 to execute other virtualized applications. In some implementations, a single RAN node 111 may represent a gNB distributed unit (DU) connected to the gNB central unit (CU) via a respective F1 interface. In these implementations, the gNB-DU may include one or more remote radio headers or RF front-end modules (RFEMs) (not shown), and the gNB-CU may be operated by a server (not shown) located in RAN 110 or by a server pool in a manner similar to CRAN / vBBUP. Alternatively, one or more of the plurality of RAN nodes 111 may be a next-generation eNB (gNB), which is a RAN node that provides E-UTRA user plane and control plane protocol terminals to UE 101 and is connected to 5GC via an NG interface.

[0032] Any node in RAN 111 can serve as the endpoint of the air interface protocol and can be the first point of contact for UE 101. In some implementations, any node in RAN 111 can perform various logical functions of RAN 110, including but not limited to the functions of the Radio Network Controller (RNC), such as radio bearer management, uplink and downlink dynamic radio resource management and data packet scheduling, and mobility management.

[0033] In the implementation, UE 101 may be configured to communicate with each other or with any of the RAN nodes 111 on a multi-carrier communication channel using orthogonal frequency division multiplexing (OFDM) communication signals, according to various communication technologies such as, but not limited to, OFDMA communication technology (e.g., for downlink communication) or single-carrier frequency division multiple access (SC-FDMA) communication technology (e.g., for uplink and ProSe or sidelink communication), but the scope of the implementation (aspect) is not limited in this respect. The OFDM signal may include multiple orthogonal subcarriers.

[0034] In some implementations, the downlink resource grid can be used for downlink transmissions from any node in RAN 111 to UE 101, while uplink transmissions can utilize similar techniques. The grid can be a time-frequency grid, referred to as a resource grid or time-frequency resource grid, which represents the physical resources in the downlink within each time slot. This time-frequency plane representation is common practice for OFDM systems, making radio resource allocation intuitive. Each column and row of the resource grid corresponds to an OFDM symbol and an OFDM subcarrier, respectively. The duration of the resource grid in the time domain corresponds to a time slot in a radio frame. The smallest time-frequency unit in the resource grid is represented as a resource element. Each resource grid comprises multiple resource blocks that describe the mapping of certain physical channels to resource elements. Each resource block comprises a set of resource elements; in the frequency domain, this can represent the minimum amount of resources currently available for allocation. Such resource blocks are used to transmit several different physical downlink channels.

[0035] According to various implementations, UE 101 and RAN node 111 transmit data (e.g., transmit and receive data) through licensed media (also referred to as “licensed spectrum” and / or “licensed band”) and unlicensed shared media (also referred to as “unlicensed spectrum” and / or “unlicensed band”). Licensed spectrum may include channels operating in the frequency range of approximately 400 MHz to approximately 2.8 GHz, while unlicensed spectrum may include a 5 GHz band.

[0036] To operate in unlicensed spectrum, UE 101 and RAN node 111 may use Licensed Assisted Access (LAA), eLAA, and / or feLAA mechanisms. In these specific implementations, UE 101 and RAN node 111 may perform one or more known medium sensing or carrier sensing operations to determine whether one or more channels in the unlicensed spectrum are unavailable or otherwise occupied before transmission in the unlicensed spectrum. Medium / carrier sensing operations may be performed according to a Listen-After-Talk (LBT) protocol.

[0037] The LAA mechanism is built on carrier aggregation (CA) technology in LTE-Advanced systems. In a CA, each aggregated carrier is called a component carrier (CC). In some cases, individual CCs may have different bandwidths than other CCs. In Time Division Duplex (TDD) systems, the number of CCs and the bandwidth of each CC may be the same for both DL and UL. The CA also includes individual serving cells to provide individual CCs. The coverage of serving cells may differ, for example, because CCs on different frequency bands will experience different path losses. The primary serving cell, or PCell, provides the primary component carrier (PCC) for both UL and DL and handles Radio Resource Control (RRC) and Non-Access Plane (NAS) related activities. Other serving cells are called SCells, and each SCell provides a single secondary component carrier (SCC) for both UL and DL. SCCs can be added and removed as needed, while changing the PCC may require UE101 to undergo a handover. In LAA, eLAA, and feLAA, some or all of the SCells can operate in unlicensed spectrum (called "LAASCell"), and LAA SCells are assisted by PCells operating in licensed spectrum. When a UE is configured to have more than one LAA SCell, the UE can receive UL authorization on the configured LAA SCell, thereby indicating different PUSCH start positions within the same subframe.

[0038] The PDSCH carries user data and higher-layer signaling to UE 101. The Physical Downlink Control Channel (PDCCH) carries information such as the transmission format and resource allocation related to the PDSCH channel. It also informs UE 101 about the transmission format, resource allocation, and Hybrid Automatic Repeat Request (HARQ) information related to the uplink shared channel. Typically, downlink scheduling (allocating control and shared channel resource blocks to UE 101b within the cell) can be performed at any RAN node of RAN node 111 based on channel quality information fed back from any UE in UE 101. Downlink resource allocation information can be transmitted on the PDCCH used for (e.g., allocated to) each UE in UE 101.

[0039] PDCCH uses Control Channel Elements (CCEs) to transmit control information. Multiple (e.g., six, etc.) CCEs can be composed of Resource Element Groups (REGs), where REGs are defined as Physical Resource Blocks (PRBs) in OFDM symbols. For example, before being mapped to resource elements, the complex-valued symbols of the PDCCH can first be organized into quadruplets, which can then be arranged using a sub-block interleaver for rate matching. One or more of these CCEs can be used to transmit each PDCCH, where each CCE can correspond to nine sets, each with four physical resource elements, called REGs. Four Quadrature Phase Shift Keying (QPSK) symbols can be mapped to each REG. Depending on the DCI size and channel conditions, one or more CCEs can be used to transmit the PDCCH. In LTE, four or more different PDCCH formats with different numbers of CCEs (e.g., aggregation levels, L = 1, 2, 4, 8, or 16) can be defined.

[0040] Some implementations may use the concept of resource allocation for control channel information, which is an extension of the above concept. For example, some implementations may utilize an extended (E)-PDCCH that uses PDSCH resources for control information transmission. One or more ECCEs may be used to transmit the EPDCCH. Similarly, each ECCE may correspond to a set of nine, each consisting of four physical resource elements, called an EREG. In some cases, an ECCE may have a different number of EREGs.

[0041] RAN nodes 110 can be configured to communicate with each other via an interface. In an implementation where system 100 is an LTE system, the interface can be an X2 interface. This X2 interface can be defined between two or more RAN nodes 111 (e.g., two or more eNBs / gNBs, etc.) connected to the evolved packet core (EPC) or core network 120, and / or between two eNBs connected to the EPC 120. In some specific implementations, the X2 interface may include an X2 user plane interface (X2-U) and an X2 control plane interface (X2-C). X2-U can provide flow control mechanisms for user packets transmitted via the X2 interface and can be used to transmit information about the delivery of user data between eNBs or gNBs. For example, X2-U can provide specific sequence number information about user data transmitted from the primary eNB (MeNB) to the secondary eNB (SeNB); information about the successful in-order delivery of PDCP Packet Data Units (PDUs) from the SeNB to UE 101 for user data; information about PDCP PDUs not delivered to UE 101; information about the current minimum expected buffer size at the SeNB for transmitting user data to the UE; and so on. X2-C can provide intra-LTE access mobility functions, including context transfer from the source eNB to the target eNB, user plane transmission control, load management functions, and inter-cell interference coordination functions.

[0042] RAN 110 is shown communicatively coupled to the core network—in this embodiment, communicatively coupled to the core network (CN) 120. CN 120 may include a plurality of network elements 122 configured to provide various data and telecommunications services to customers / subscribers (e.g., users of UE 101) connected to CN 120 via RAN 110. Components of CN 120 may be implemented in a single physical node or separate physical nodes, including components for reading and executing instructions from machine-readable or computer-readable media (e.g., non-transitory machine-readable storage media). In some embodiments, NFV may be used to virtualize any or all of the aforementioned network node functions via executable instructions stored in one or more computer-readable storage media (described in further detail below). A logical instance of CN 120 may be referred to as a network slice, and a logical instance of a portion of CN 120 may be referred to as a network subslice. Network Function Virtualization (NFV) architectures and infrastructure may be used to virtualize one or more network functions onto a physical resource comprising a combination of industry-standard server hardware, storage hardware, or switches (optionally performed by proprietary hardware). In other words, NFV systems can be used to execute virtual or reconfigurable concrete implementations of one or more Evolution Packet Core (EPC) components / functions.

[0043] Generally, application server 130 may be an element that provides IP bearer resources for use with the core network (e.g., Universal Mobile Telecommunications System Packet Service (UMTS PS) domain, LTE PS data service, etc.). Application server 130 may also be configured to support one or more communication services for UE 101 via EPC 120 (e.g., VoIP sessions, PTT sessions, group communication sessions, social networking services, etc.).

[0044] In the implementation scheme, CN 120 can be a 5GC or a 5GC 120, and RAN 110 can be connected to CN 120 via NG interface 113. In the implementation scheme, NG interface 113 can be divided into two parts: a Next Generation (NG) User Plane (NG-U) interface 114, which carries traffic data between RAN node 111 and the User Plane Function (UPF); and an S1 Control Plane (NG-C) interface 115, which is the signaling interface between RAN node 111 and the Access and Mobility Management Function (AMF). The core network CN 120 can also be a 5GC 120.

[0045] In one implementation, CN 120 may be a 5G CN (referred to as "5GC 120", etc.), while in other implementations, CN 120 may be an evolved packet core (EPC). When CN 120 is an EPC (referred to as "EPC 120", etc.), RAN 110 may be connected to CN 120 via S1 interface 113. In another implementation, S1 interface 113 may be divided into two parts: an S1 user plane (S1-U) interface 114, which carries traffic data between RAN node 111 and S-GW; and an S1-MME interface 115, which is the signaling interface between RAN node 111 and MME.

[0046] refer to Figure 2 This diagram illustrates a user equipment (UE) device or other network device / component (e.g., gNB, eNB, or other participating network entities / components). The UE device 200 includes: one or more processors 210 (e.g., one or more baseband processors) including processing circuitry and associated interfaces; transceiver circuitry 220 (e.g., including RF circuitry, which may include transmitter circuitry (e.g., associated with one or more transmit chains) and / or receiver circuitry (e.g., associated with one or more receive chains), the transmitter and receiver circuitry may employ common circuitry elements, different circuitry elements, or combinations thereof); and memory 230 (which may include any of a variety of storage media and may store instructions and / or data associated with one or more of the processors 210 or transceiver circuitry 220).

[0047] Additionally, memory 230 (and other memory components discussed herein, such as memory, data storage devices, etc.) may include one or more machine-readable media comprising instructions that, when executed by the machine or components herein, cause the machine to perform actions of a method, apparatus, or system for concurrent communication using various communication technologies according to the embodiments and examples described herein. It should be understood that the aspects described herein can be implemented by hardware, software, firmware, or any combination thereof. When implemented in software, functionality may be stored as one or more instructions or code on or transmitted via a computer-readable medium (e.g., the memory or other storage device described herein). Computer-readable media includes both computer storage media and communication media, including any medium that facilitates the transfer of a computer program from one place to another. Storage media or computer-readable storage devices may be any available medium accessible by a general-purpose or special-purpose computer. By way of example only and not limitation, such computer-readable media may include RAM, ROM, EEPROM, CD-ROM or other optical disk storage devices, magnetic disk storage devices or other magnetic storage devices, or other tangible and / or non-transitory media that can be used to carry or store desired information or executable instructions. Furthermore, any connection may also be referred to as a computer-readable medium. For example, if software is transmitted from a website, server, or other remote source using coaxial cable, fiber optic cable, twisted pair, digital subscriber line (DSL), or wireless technologies such as infrared, radio, and microwave, then coaxial cable, fiber optic cable, twisted pair, DSL, or wireless technologies such as infrared, radio, and microwave are included in the definition of the medium. As described in more detail below, System 400 can facilitate higher power efficiency for beam management operations, including CSI reporting / feedback based on a hierarchical precoding scheme.

[0048] Depending on the specifics, the UE 200 / 101 is operable to configure a Channel State Information (CSI) reporting configuration so that the Precoding Matrix Indicator (PMI) can be used as CSI feedback (report) associated with the Rank Indicator (RI), Wideband Channel Quality Indicator (CQI), or Subband CQI. The PMI precoder can be configured based on a hierarchical precoding scheme used for hierarchical frequency-selective precoding to configure CSI feedback from the UE 200 / 101. Transmission can then be processed by gNB 111, 112, or 200 for beamforming based on the codebook formed by the feedback.

[0049] For example, CSI feedback for FDD or TDD can be based on partial reciprocity between UE 101 and gNB 111. Theoretically, not all multipath parameters for FDD downlink and uplink channels must be equivalent. Therefore, full reciprocity is not necessarily true, while partial reciprocity is. Uplink sounding reference signals (SRS) are primarily used for CSI measurements to enable UL frequency scheduling and link adaptation. For example, in TDD, by utilizing channel reciprocity, the transmitter or gNB 111 can estimate the downlink channel based on the SRS on the uplink channel. However, such reciprocity depends on the accurate calibration of the transceiver RF chain at gNB 111. The sounding mechanism used to estimate UL channels over different bandwidths (subbands or wideband) depends on the terminal channel conditions. Terminals near gNB 111 are not necessarily power-limited and can therefore allocate wideband sounding to provide CSI estimates across the entire band. On the other hand, cell-edge terminals are power-limited and can only allocate power to a limited number of subbands. The gNB 111 relies on CSI to coherently process the antenna. For example, the gNB 111 utilizes subband spacing information, but ensuring such information can incur overhead costs, especially for MIMO schemes. Therefore, subband feedback in the CSI for the gNB 111 can be beneficial, particularly compared to PMI feedback in the context of constrained CSI feedback.

[0050] In a specific example of SRS signaling, UE 101, for example, uses the uplink carrier frequency f u The gNB 111 sends an SRS signal. The gNB 111 can utilize multiple Rx antennas to receive the SRS and extract parameters / characteristics from the received signal, such as angle of arrival (AoA), delay spread, angle spread, and average AoD (transmit angle). The gNB 111 assumes the same parameters / characteristics or uses them for the downlink frequency f. d The parameters / characteristics are derived from the frequency conversion. After generating the precoder for CSI-RS, the gNB111 can derive the parameters / characteristics based on the constructed downlink frequency f. d The parameters are applied to the precoder for the transmission of CSI-RS as precoded CSI-RS. The gNB 111 can also employ frequency-selective (subband-based) precoding for the CSI-RS. The UE101 can then receive the CSI-RS and respond by feeding back the wideband PMI and subband CQI as CSI feedback to the network. However, CSI feedback can affect network system performance regarding average throughput or cell-edge throughput.

[0051] On one hand, the hierarchical precoding scheme can be configured by UE 101 by configuring the precoding hierarchy structure. For example, a frequency band or bandwidth can be divided into frequency portions and configured as a hierarchical tree, such that these divided portions form different hierarchical levels of the precoding hierarchy structure. Frequency portions can be further subdivided into subbands. If differences are realized in the precoders associated with the subbands, these precoders are not eliminated and are retained for transmission in CSI feedback. However, if no differences are observed between the frequency portions and subbands, the frequency portions of the subbands of the frequency portions are eliminated. Therefore, the hierarchical precoding scheme can selectively reduce the amount of feedback overhead used for CSI feedback, improve efficiency, and eliminate network costs in terms of resources.

[0052] refer to Figure 3 This illustrates an example of a precoding hierarchy structure configured for performing hierarchical frequency-selective precoding based on various aspects (or implementation aspects). The precoding hierarchy structure 300 includes a root frequency portion 302 that includes a broadband or frequency band considered for generating the PMI precoder in CSI feedback. The root frequency portion may be specified as indexed as frequency portion P. 0,0 The root frequency portion 300 corresponds to the lowest index level of the precoding hierarchy 300, as shown at the top level of the precoding hierarchy 300. Although three hierarchical precoding levels (level 0, level 1, level 2) are shown, the precoding hierarchy 300 can be configured to have any number of hierarchical levels.

[0053] The next higher index level (level 1) relative to the root frequency portion 302 corresponds to frequency portions 304 and 306 that have already been divided from the root frequency portion 302. This root frequency portion includes, for example, both frequency portions 302 and 304, as well as subbands 308, 310, 312, and 314. Indexed as frequency portion P 1,0 P 1,1 Each frequency segment 304 and 306 is further subdivided (sub-divided) into subbands 308 to 314 at the highest index level (level 2) of the precoding hierarchy 300, as indexed as P. 2，0 P 2，1 P 2，2 P 2，3 Sub-band.

[0054] Each subband can belong to a frequency range at level H, where H can be any integer greater than 0. In one example, level H can be represented as follows: Where N can be a subband used for CSI feedback (e.g., indexed as P) 2,0 P 2,1 P 2,2 P 2,3The number of subbands (308 to 314). At level 0 (root), there exists a single frequency section P. 0，0 The root frequency portion 302 consists of all subbands 308 to 314. At level 1, the frequency portion P is at a higher index level (level 1) than level 0. 0，0 Below, there exists a component P indexed as the frequency part. 1,0 P 1,1 The two frequency sections are 304 and 306.

[0055] In summary, at hierarchical precoding level h, for the frequency part P h-1，m m = 0, ..., 2 h-1 -1, according to level h-1, there are two frequency components P h，2m and P h，2m+1 These two frequency sections will separate the sub-band from frequency section P. h-1，m The partitions are roughly equal in size; alternatively, the partitions can be formalized such that there exists a subtree P. h-1，m Two subtrees (leaf) P h，2m and P h，2m+1 For a specific N that is not a power of 2, the precoding hierarchy can be configured such that at a given hierarchical precoding level, only subtree P exists. h-1，m A subtree (leaf) P h，2m or P h，2m+1 (For example, for the leftmost leaf or the rightmost leaf). For example, for N=7, P 3，7 or P 3，0 exist Figure 4 It may not exist in (note) Figure 4 (This illustration is for N=8). In another case, some leaves (or one leaf, as a frequency component or subband) on the rightmost side and some leaves (one leaf) on the leftmost side may not necessarily exist at a given hierarchical precoding level.

[0056] In one respect, the frequency portion P indexed as being at level 1 1,0 P 1,1 Frequency sections 304 and 306 can be divided into those from frequency section P. 0，0The subbands are roughly equal in number. Therefore, each frequency portion of the precoding hierarchy 300 can be a nearly equal or equal division of a parent frequency portion at a lower index level. Specifically, a wideband precoder can still be configured for all four subbands, but the wideband frequency portion can be divided into two parts. For example, if a certain number (e.g., 32 or other) of Physical Resource Blocks (PRBs) are divided into two parts, another precoder can be configured to enter one frequency portion of a PRB, and if the differences between peer portions (e.g., 308 or 310) from the same parent frequency portion (e.g., 304) are small or negligible, these subbands (e.g., 308, 310) can be eliminated from CSI feedback. Similar evaluation / elimination can be performed throughout the precoder hierarchy, for example, to select individual subbands and associated parent portions for feedback. Then, for other subbands under the lower index frequency portion, the same operation can be performed, where the PRB can again be divided into two parts, and two additional PMI precoders can be configured and compared. For example, if the differences are not significant enough, no feedback overhead will be incurred for these sections or subbands. In this way, the same performance can be achieved for PMI, but with less overhead feedback.

[0057] In one example, pruning or elimination can be performed or analyzed using either a top-down or bottom-up approach. Here, one or more bitmaps corresponding to different hierarchical precoding levels can be configured or evaluated using a bottom-up approach, starting with the lowest index hierarchical precoding level in the hierarchical precoding structure of the hierarchical precoding scheme. For example, the lowest index hierarchical precoding level includes a frequency band as root frequency portion 302. Alternatively or additionally, one or more bitmaps can be configured or evaluated using a bottom-up approach, starting with the highest index hierarchical precoding level (such as subbands 308 to 314), corresponding to different hierarchical precoding levels. One or both methods can be used, for example, to determine the precoder location based on CSI feedback provided by UE 101 to gNB 111 according to the hierarchical precoding scheme.

[0058] Alternatively or otherwise, the precoding hierarchy may be configured such that there are two subtrees (leaves) 304 and 306 from the root 302 of the hierarchical structure tree including the precoding hierarchy 300. For example, each of these may further form branches in the subtree, which are further divided into subbands 308 and 310 subdivided from the frequency portion 304 and subbands 312 and 314 subdivided from the frequency portion 306. Although the three levels including the root frequency portion 302 at level 0, the frequency portions 304 and 306 at level 1, and the subbands 308 to 314 at level 2 are shown as three levels, one or more different hierarchical precoding levels are also configured as part of the precoding hierarchy 300 to form additional frequency portions or subbands for determining CSI feedback. In summary, feedback information from different hierarchical levels can be used in several ways: First, feedback information from the root level to the highest index level can be utilized, which can take the form of a product of precoder applied at different hierarchical levels, or in the form of applying all the underlying feedback parameters at different hierarchical levels to produce composite feedback parameters applicable to the current subband; in the second way, feedback information can come from the single hierarchical level used.

[0059] The same partitioning process corresponding to the precoder hierarchy 300 can be configured by UE 101 up to level H for generating a precoder for CSI feedback, where H represents the number of hierarchical levels in the precoder hierarchy. UE 101 generates precoders associated with frequency portions 304, 306 or subbands 308 to 314 at different hierarchical levels (hierarchical precoder levels). For example, W h，m This can correspond to the precoder and frequency part m at the hierarchical precoder level h, where h = 0, 1, ..., H and m = 0, ..., 2 h -1. Size W 0，0 It can be represented as N tx ×R, where N tx It can represent the CSI RS port number, and R represents the feedback rank indicator (RI) value.

[0060] Alternatively, or otherwise, W 0，0 It can be represented as and B 0，0 The product of , where W 0，0 It is N tx ×R1, and B 0，0 It is R1×R, N tx R1 can be the CSI-RS port number, and it can be a parameter that depends on the number or value of the feedback rank indicators (RI), where R1 > R. The parameter R1 can be used to distinguish these values ​​from R as seen for R = 1: if R1 = R, where because W 0，0Since it's already a rank-1 precoder, it might be difficult to incorporate frequency adoption. However, with R1=2, for example, different combination coefficients or rotation matrices can be configured accordingly to adopt the channel to the frequency.

[0061] Alternatively, or otherwise, for h = 0, 1, ..., H, and m = 0, ..., 2 h -1, generate two matrices A h，m and B h，m A h，m It is R1×R1, and B h，m It is rank-dependent, for example, R1×R. Then the precoder for subband n can be derived from... Given, among which

[0062] On the other hand, UE 101 can configure feedback overhead according to one or more overhead reduction mechanisms. For example, UE 101 can configure each hierarchical precoding level differently with different amounts of feedback overhead. At the root level or level 0, the feedback overhead can be higher, and subsequently gradually, the feedback overhead at higher index levels (e.g., level 1 or level 2) can be less restricted, or prevented from increasing after a predefined level. At the root frequency section 302, for example, a larger amount of information with higher feedback priority is utilized, and thus more granular additional information (e.g., rotation angle or other parameter data) is defined for CSI feedback. At each lower level or higher index hierarchical level, refinement can be performed to make the information coarser or less detailed, with lower priority, and thus utilize fewer information bits for CSI feedback. In one example, the rotation angle of a precoder codebook with a precoder for CSI feedback may have a progressively coarser resolution for rotation angles at higher index hierarchical precoding levels (e.g., level 1 with frequency portions (304, 306) or level 2 with subbands (308 to 314) than for rotation angles at lower index hierarchical precoding levels for hierarchical precoding schemes (e.g., level 1, root 302).

[0063] On the other hand, UE 101 can configure feedback overhead according to one or more overhead reduction mechanisms, which include pruning individual subbands or as a subtree formed together with child nodes (e.g., subbands 308, 310, 312, or 314) of a parent hierarchical level from one or more frequency portions (e.g., 304 or 306) in a hierarchical precoding scheme. For some subtrees, it is not necessary to make more fine distinctions between their two child nodes (therefore, it is not necessary to distinguish all descendants (e.g., subbands 308 and 310 of this particular subtree (e.g., parent frequency portion 304)). In this case, the entire subtree structure (e.g., subbands 308 and 310 of frequency portion 304) can be pruned without incurring feedback overhead for its descendants (e.g., subbands 308 and 310). Related to this mechanism, UE 101 can be configured with a bitmap representing subbands 308 to 314 in the available CSI reports, where each bit can correspond to subbands 308 to 314. UE 101 can use hierarchical precoding levels to configure the bitmap to indicate unpruned and pruned subbands associated with CSI feedback.

[0064] For example, for a given subband, "0" can indicate that there is no feedback at level H, and "1" can indicate that feedback is provided at level H, or vice versa.

[0065] In other aspects, feedback overhead reduction can be configured by combining the above-mentioned aspects for reduction or by utilizing each aspect independently, so that it is generally consistent with hierarchical precoding schemes and does not depend directly on the physical characteristics of the channel, but rather on the channel correlation between CSI pairs or related parameters. For example, pruning can be used in combination with coarser feedback along with higher indexed precoding levels.

[0066] The number N can be determined based on the number of PRBs in the bandwidth section and the subband size, which is similar to the configurable subband sizes found in TS 38.214 with reference to Table 5.2.1.4-2. When N subbands are not a power of 2, the frequency section can be determined based on a fixed size or adapted to the size of its parent frequency section, thus approximately equal sections are assigned to sibling sections or subsections. In a simplified example, N = 4 subbands can be generated for CSI reporting, which can be numbered B. k k = 1, 2, 3, ..., N. Here, for simplicity, N is a power of 2, but further descriptions are provided below where N is not a power of 2, such as... Figure 4 As shown. UE 101 can generate a precoder representation W representing the following. h，mThe pre-encoder can be a pre-encoder located in the hierarchical structure h and the frequency portion m. UE 101 generates a pre-encoder in the hierarchical structure h = 0, 1, ..., 2 for use in broadband or bandgap applications. 0，0 This can represent a wideband pre-encoder associated with root 402 for all frequency portions having sub-bands. Dimension W 0，0 Can be derived from N tx ×R represents, where N tx This is the CSI RS port number, and R is the feedback rank, which can be a matrix or a value. W 1，0 This can represent the first part used for sub-bands (i.e., sub-bands 1, 2, and W). 1，1 The additional precoder can be used for the second part of the sub-band (e.g., for level 1, i.e., 3, 4). Similarly, the second-level precoder can be provided by W. 2，m The expression indicates that m = 0, 1, 2, 3, which corresponds to the additional pre-encoder used for the (m+1)th quarter sub-band (i.e. sub-band m).

[0067] Make the pre-encoder W h，m The parameter a h，m Parameterization, therefore W h，m =G(a h，m ), where G(.) is the mapping function. For example, a precoder can be generated for the first subband 308, which can correspond to G(a 0，0 +a 1，0 +a 2，0 The precoder is represented by G(a). A precoder can be generated for the second subband 310, which can be generated by G(a). 0，0 +a 1，0 +a 2，1 ) represents. A precoder can be generated for the third subband 312, which can be generated by G(a 0，0 +a 1，1 +a 2，2 ) represents. A precoder can be generated for the fourth subband 314, which can be generated by G(a 0，0 +a 1，1 +a 2，3 )express.

[0068] In addition to or alternatively, for W h，m The codebook construction can be as configured by UE 101 to provide to gNB 111, with a gradually coarser resolution, or with a given rotation having a coarser resolution for the rotation angle (e.g., W with type II). 0，0 W when h > 0 h，mA given rotation configured to selectively reduce CSI feedback overhead may have progressively coarser resolution for rotation angles. UE 101 may generate a precoder codebook with a precoder for CSI feedback, which includes progressively coarser resolution for rotation angles at higher index-level precoding stages than at lower index-level precoding stages, independent of or in combination with pruning mechanisms for selectively reducing CSI feedback overhead.

[0069] Alternatively, in the hierarchical structure precoding, the hierarchical part h and the frequency part m, h = 0, 1, ..., H and m = 0, ..., 2 h -1, pre-encoder W h，m Having size N tx ×R, where N tx It can represent the CSI RS port number, and R represents the feedback rank indicator (RI) value.

[0070] refer to Figure 4 This illustrates another example of a precoding hierarchy structure for a hierarchical precoding scheme, according to various aspects or implementations. The precoding hierarchy structure 400 includes structures having, for example... Figure 3 The frequency portions 404 to 414 and subbands 416 to 432, similar to the index shown, enable the frequency portion P from level h-1 in the hierarchical precoding layer H to be used for the hierarchical precoding level h. h-1，m This means that m = 0, ..., 2 h-1 -1. UE 101 can transmit the frequency portion P h-1，m Divided into two frequency parts P h，2m and P h，2m+1 For example, the two frequency components can be approximately equal; alternatively, the partition can be formulated such that there exists a frequency from subtree P. h-1，m Two subtrees (leaf) P h，2m and P h，2m+1 .

[0071] In one aspect, as part of a hierarchical precoding scheme, UE 101 may prune one or more hierarchical precoding levels (e.g., levels 1 to 3) of frequency portions 404 to 414 or subbands 416 to 432 based on an overhead reduction mechanism for CSI feedback. A bitmap for each hierarchical precoding level can then be configured by UE 101, indicating the unpruned and pruned subbands associated with CSI feedback. Figure 4 As shown, for example, the trimmed subbands 416 to 430 are indicated by the X above them, and are therefore eliminated in the CSI feedback to gNB 111 to reduce feedback overhead.

[0072] Specifically, UE 101 can determine whether there are predetermined differences or differences in precoder configuration between subbands, and can subsequently eliminate these precoders associated with the subbands from the feedback. Therefore, in the exemplary precoding hierarchy 400, only subband 432 and parent frequency portions 414, 406, and 402 are configured in the CSI feedback. For example, UE 101 can make such a determination for differences between precoders corresponding to any two subbands (e.g., 416 and 418) of a subtree or the frequency portions from which they are divided (e.g., 408). Similarly, a similar determination can be made through precoding hierarchy 400 until a single subband (e.g., 432, etc.) for the CSI feedback is determined. UE 101 selects the lowest level of the precoding hierarchy subband for the CSI feedback precoder and can subsequently generate precoding for frequency bands in frequency portions that include one or more hierarchical precoding levels of the precoding hierarchy that include the subband selected by the precoder for the CSI feedback.

[0073] Alternatively or otherwise, the precoder may be configured or mapped to CSI feedback for each hierarchical level of the precoding hierarchy, or to any one or more hierarchical levels within the precoding hierarchy. For example, a bitmap or mapping to the CSI feedback may be generated at a hierarchical precoding level above the highest index precoding level, such as only at level 2, level 1, or level 0, or any combination of hierarchical levels. A bitmap or mapping to the CSI feedback may be generated or determined only for the highest index hierarchical level (e.g., level 3) or any one or more hierarchical levels of the precoding hierarchy. For example, any combination of one or more hierarchical levels may be associated with one or more bitmaps generated or mapped for association with one or more precoders.

[0074] Using the established symbols, to connect with the above Figure 3 Similarly, a precoder can be generated based on the selected sub-band, where in Figure 3 In the text, the first, second, third, and fourth sub-bands can correspond to their respective representations: W 2，0 W 2，1 W 2，2 and W 2，3 . Figure 4 Another example is shown where there are N = 8 subbands for CSI feedback reporting. Here, UE 101 can report a level 3 bitmap [0000 00 01], where the level can be H = log2(8) = 3, representing the highest index level; and for level 2, the UE reports [0 0 0 1], and for level 1, the UE reports [0 1]. Then, in response to receiving such feedback, gNB 111 can configure or infer information based on different bitmaps. For example, based on the level 1 bitmap, gNB 111 can determine W 1，0Not included in the feedback, but W 1，1 Included in the feedback. For example, based on the level 2 bitmap, gNB 111 can be further determined as: W 2，0 W 2，1 W 2，2 Not included in the feedback, but W 2，3 Included in the feedback. Based on the level 3 bitmap, gNB 111 can further determine W. 3，k k = 0, 1, 2, 4, 5, 6 is not included in the feedback, but W 3，7 Included in the feedback.

[0075] Alternatively or in response to receiving CSI feedback from UE 101, gNB 111 may configure the PMI precoder component from level 0 to level H without considering subtree pruning, as follows:

[0076] W 0，0 ,

[0077] W 1，0 W 1，1 ,

[0078] W 2，0 W 2，1 W 2，2 W 2，3 ,

[0079] W 3，0 W 3，1 W 3，2 W 3，3 W 3，4 W 3，5 W 3，6 W 3，7 .

[0080] When considering subtree pruning, gNB 111 can arrange PMI components from level 0 to level H, where underlined components are not included in CSI reports, as follows:

[0081] W 0，0 ,

[0082] W 1，0 W 1，1 ,

[0083] W 2，0 , W 2，1 , W 2，2 W 2，3 ,

[0084] W 3，0 , W 3，1 , W 3，2 , W 3，3 , W 3，4 ,W 3，5 ， W 3，6 ，W 3，7

[0085] The omission of underlined components can be fully determined by gNB 111 based on the level 1 to level H bitmap included in the CSI feedback, or provided by higher-layer signaling (e.g., RRC signaling, etc.). Therefore, according to one implementation or aspect, gNB 111 can process the CSI feedback provided by UE 101, for example, based on omission rules. Typical CSI feedback also includes RI (rank indicator), wideband CQI, and subband CQI, which may be different from the wideband CQI. Up to eight transmit layers are supported, considering NR. If RI indicates five or more spatial layers, these spatial layers are mapped to two transport blocks, and the CQI and subband CQI are calculated separately for each transport. It can be seen that the CSI feedback is not fixed, depending on whether RI > 4 and the number of pruned subbands selected (and correspondingly, the number of unpruned subbands). To aid decoding on the gNB side, CSI feedback can be divided into two parts: Part 1 includes the RI, wideband CQI, subband CQI for the first transport block, and a bitmap indicating trimmed / untrimmed subbands; Part 2, in the second transmission or feedback, includes the subband CQI for the second transport block and PMI feedback as given below in the readout sequence. If more than one CSI-RS resource is provided to the UE for hierarchical precoding feedback, the CRI (CSI-RS Resource Indicator) can also be included in the first part (or Part 1) of the CSI feedback, which can be in a transmission for feedback that is different from / separate from the second part of the CSI. Specifically, omitting rules can be configured based on when the feedback overhead for a given rank is greater than the feedback overhead that can be sent back to gNB 111 by gNB 111 using specified resources. Based on the hierarchical precoding scheme described according to aspects or embodiments herein, the readouts or reports provided by UE 101 in response to feedback can be a sequential order from the lowest index level (i.e., level 0) to the highest index level (i.e., level H) of the precoder, or alternatively, a sequential order from the highest index level to the lowest index level of the precoder. At the same level, readouts are from the lowest index frequency portion to the highest index frequency portion. For example, UE 101 can be configured to read out no more than that of the precoder components given by the specified resources. Therefore, for example, resource or CSI limits can be provided to UE 101 by gNB 111 or higher-layer signaling. In this way, in response to exceeding the limits, two-step CSI feedback can be configured by UE 101. In the first step, a level H bitmap can be included in the first part or step of the CSI feedback. For example, gNB 111 can determine the size of the feedback based on the bitmap, where its feed size can be constant, and the bitmap shows the size of the feedback attached to the precoder, which can be included in the second part or step with the second CSI feedback.

[0086] In one example, pruning or elimination can be performed or analyzed using either a top-down or bottom-up approach. Here, one or more bitmaps corresponding to different hierarchical precoding levels can be configured or evaluated using a bottom-up approach, starting from the lowest index hierarchical precoding level in the hierarchical precoding structure of the hierarchical precoding scheme. For example, the lowest index hierarchical precoding level includes a frequency band as the root frequency portion. Alternatively or otherwise, these bitmaps can be configured by UE 101 corresponding to each hierarchical precoding level, or evaluated by gNB 111 corresponding to each hierarchical precoding level, using a bottom-up approach starting from the highest index hierarchical precoding level.

[0087] On the other hand, hierarchical coding can be configured as a product of multiple precoders, where similar processing can be applied to one or more parameters. For example, UE 101 can configure the precoder to be parameterized by α and β, such as W(α, β). Here, α and β can be functions of frequency, and the broadband parameter function for α can be an average over all N subbands, and α h，m It can be in P h，m The value applied above. Here, the issue arises in using different quantization levels for different subtrees, where higher levels can use progressively smaller bits.

[0088] refer to Figure 5 This illustrates a similar approach to hierarchical precoding schemes based on various aspects. Figure 4 Another exemplary precoding hierarchy 500 is provided for the precoding hierarchy 400. As described above, feedback information from different hierarchy levels can be used in various ways. For example, feedback information from the root level 402 (level 0) to the highest index level (level 3) can be utilized, which can take the form of a product of precoder applications at different hierarchy levels or a selection of precoder applications at different hierarchy levels, corresponding to unpruned leaves or unpruned subbands as part of the hierarchical tree structure of the precoding hierarchy 500. The report used to read out or determine the position of the precoder at gNB 111 corresponding to the CSI feedback can be from the lowest index level (i.e., level 0) to the highest index level (i.e., level H). At the same level, readouts (presentation, processing, or other means of evaluation or provision) can be from the lowest index frequency portion to the highest index frequency portion. For example, the evaluation or readout of the corresponding precoder for the CSI feedback can start from the highest index level. If a leaf (as a frequency portion or subband) is "0", then the leaf can be pruned; otherwise, the leaf is not pruned, where the corresponding bit in the bitmap can be "1" (or vice versa). For another index level, if both sub-leafs of a leaf are "0", then the leaf is pruned; otherwise, the leaf is not pruned.

[0089] Alternatively or otherwise, the hierarchical precoding level of the frequency portion (e.g., level 2) may have more than one unpruned frequency portion, wherein although Figure 5 The child nodes (424 and 426) are pruned, but the frequency portion corresponding to part 412 can still be reported and identified in the CSI feedback. For example, level 2 may include bits [0 0 1 1].

[0090] Alternatively, for the highest index level, if a leaf (as a frequency component or subband) is "0", then the leaf is pruned or marked for omission; otherwise, the leaf is not pruned or marked for omission. For leaves at levels between the highest index level and the top level (root level), if the leaf is "0", then the leaf is pruned or marked for omission; if the leaf is "1", then the leaf is pruned.

[0091] If at least one cotyledon is "0", the leaf is not pruned or marked for omission; otherwise (both cotyledons are "1"), the leaf is pruned or marked for omission. For the top level, if at least one cotyledon is "0", the leaf is not pruned or marked for omission; otherwise (both cotyledons are "1"), the leaf is pruned or marked for omission. The precoder for pruned leaves (or marked for omission) is not included in the CSI feedback. Note that this pruning process can be used for cases where the UE feeds back a single bitmap of the highest index level, or for cases where the UE feeds back bitmaps of multiple or all hierarchical levels. In the case of bitmaps of multiple or all hierarchical levels, they are included in the first part of the CSI report.

[0092] Alternatively, gNB 111 can reconstruct the applicable precoder from the CSI feedback using sequences from bottom to top or from the highest index level to the lowest index level (or vice versa), and sequences from left to right or from the lowest index frequency portion to the highest index frequency portion at each level. For example, subband 432 may have its own precoder, while subbands 424 or 426 may have a precoder derived from parent 412, and subband 430 may have a precoder derived from parent 414. Subbands 416, 418, 420, and 422 may have a precoder derived from great-grandfather 402. Working in reverse from the highest index level to the lowest index level, the precoder used for the parent will be applied to the subband's precoder.

[0093] refer to Figure 6An exemplary processing flow 600 for a network device or component (e.g., UE 101, base station 110, AP 106, or other network component) is illustrated to perform a hierarchical precoding scheme according to various aspects / implementations described herein. Processing flow 600 begins at 602, where CSI-RS within one or more OFDM symbols is received. At 604, according to any one or more aspects described herein, the processing flow further includes generating Channel State Information (CSI) feedback based on a hierarchical precoding scheme that selectively reduces feedback overhead associated with the CSI feedback. The UE may further transmit the CSI feedback to the base station.

[0094] In one aspect, UE 101 may, for example, subdivide the frequency band of a hierarchical precoding level into frequency portions at one or more lower hierarchical levels for a hierarchical precoding scheme. For example, it may be possible to subdivide the frequency portions at one or more hierarchical levels into subbands to form a subtree of the precoding hierarchy structure, wherein these frequency portions include equally divided frequency portions of the frequency band, and the subbands include the highest indexed hierarchical precoding level for the hierarchical precoding scheme.

[0095] In response to CSI feedback exceeding the feedback payload limit, CSI feedback can be generated in two parts by providing a bitmap of the subband and further providing CSI feedback associated with a precoding matrix index (PMI) precoder based on a hierarchical precoding scheme. The bitmap of these subbands indicates which subbands or frequency portions are associated with the CSI feedback.

[0096] refer to Figure 7 An exemplary processing flow 700 is illustrated for a network device or component (e.g., eNB / gNB 111, base station 110, AP 106, or other network component) to perform a hierarchical precoding scheme according to various aspects / implementations described herein. Processing flow 700 begins at 702, where a Channel State Information Reference Signal (CSI-RS) is provided for CSI feedback. At 704, the processing flow includes receiving CSI feedback for the frequency portion corresponding to the hierarchical precoding level of the broadband frequency based on the hierarchical precoding scheme.

[0097] In one aspect, the gNB 111 or other network components may determine which precoders correspond to one or more frequency portions or one or more subbands of the hierarchical precoding level associated with the CSI feedback, in order to pair the CSI feedback with a physical channel for the UE. The precoders may be configured based on the product of a first matrix and a second matrix for the hierarchical precoding level of the hierarchical precoding scheme, wherein the first matrix includes CSI-RS port numbers and the second matrix is ​​rank-dependent based on the feedback rank indicator (RI). Alternatively or otherwise, the precoders may be configured based on a separate matrix of CSI-RS port numbers with rank values.

[0098] Bitmaps corresponding to the hierarchical precoding levels can be further generated based on either a bottom-up approach starting from the first hierarchical level (including the root frequency portion) or a bottom-up approach starting from the highest index hierarchical level (including the frequency portion within the subtree branch partition of the subband derived from the root frequency portion). These can then be used to evaluate or reconstruct the CSI feedback.

[0099] In one aspect, for example, the payload limit associated with the CSI feedback may be provided by gNB 111 or received by UE 101. In response to the CSI feedback exceeding the payload limit, a bitmap indicating one or more precoders associated with the CSI feedback, as well as other precoders omitted from the CSI feedback, may be received and processed, while a second CSI feedback is received based on the payload size indicated by the bitmap. The size of the feedback may be further determined based on the bitmap for resource allocation accordingly.

[0100] As used herein, the term "processor" can refer to virtually any computing processing unit or device, including but not limited to single-core processors; single-processors with software multithreading capabilities; multi-core processors; multi-core processors with software multithreading capabilities; multi-core processors with hardware multithreading technology; parallel platforms; and parallel platforms with distributed shared memory. Additionally, a processor can refer to an integrated circuit, application-specific integrated circuit, digital signal processor, field-programmable gate array, programmable logic controller, complex programmable logic device, discrete gate or transistor logic, discrete hardware components, or any combination thereof designed to perform the functions and / or processes described herein. Processors can utilize nanoscale architectures, such as, but not limited to, molecular and quantum dot-based transistors, switches, and gates, to optimize space utilization or enhance the performance of mobile devices. Processors can also be implemented as a combination of computing processing units.

[0101] Implementations may include subjects such as methods, means for performing actions or blocks of the methods, at least one machine-readable medium including instructions that, when executed by a machine (e.g., a processor with memory, an application-specific integrated circuit (ASIC), a field-programmable gate array (FPGA), etc.), cause the machine to perform actions of a method, apparatus, or system for concurrent communication using various communication technologies according to the implementations and embodiments described herein.

[0102] The first embodiment is a set of user equipment (UE) devices, including: a memory; a processor configured to: receive a channel state information reference signal (CSI-RS) within one or more orthogonal frequency division multiplexing (OFDM) symbols; generate channel state information (CSI) feedback based on a hierarchical precoding scheme that selectively reduces feedback overhead associated with the CSI feedback; and transmit the CSI feedback to a base station.

[0103] The second embodiment may include the first embodiment, wherein the processor is further configured to: subdivide the frequency band into different hierarchical precoding levels of a precoding hierarchy structure for a hierarchical precoding scheme.

[0104] The third embodiment may include the first or second embodiment, wherein the different hierarchical precoding levels of the precoding hierarchy include: at least one hierarchical precoding level, the at least one hierarchical precoding level including the frequency portion of the frequency band; and at least one other hierarchical precoding level, the at least one other hierarchical precoding level being lower than the at least one hierarchical precoding level.

[0105] The fourth embodiment may include any one or more embodiments of the first to third embodiments, wherein the at least one other hierarchical precoding level includes a subband formed from the frequency portion of the at least one hierarchical precoding level as a subtree of the precoding hierarchy structure.

[0106] The fifth embodiment may include any one or more embodiments of the first to fourth embodiments, wherein the processor is further configured to: select (map, determine or identify) the subband of the highest index level of the precoding hierarchy for the precoder feedback.

[0107] The sixth embodiment may include any one or more embodiments of the first to fifth embodiments, wherein the processor is further configured to generate CSI feedback including a bitmap indicating unpruned and pruned subbands among the subbands of the highest indexed hierarchical precoding level of the precoding hierarchy structure for the hierarchical precoding scheme.

[0108] The seventh embodiment may include any one or more embodiments of the first to sixth embodiments, wherein the processor is further configured to generate CSI feedback based on the bitmap, the CSI feedback including feedback corresponding to the frequency portions of unpruned subbands having a range from the lowest index-level precoding level to the highest index-level precoding level, and increasing with the index of the frequency portions at the same index-level precoding level.

[0109] The eighth embodiment may include any one or more embodiments of the first to seventh embodiments, wherein the processor is further configured to: provide feedback including one or more of the following: a CSI-RS resource indicator (CRI), a rank indicator (RI), a wideband channel quality indicator (CQI) for a first transport block, a subband CQI for a first transport block having an ascending order of subband indices, wherein a bitmap indicates unpruned and pruned subbands among subbands of the highest index-level precoding level; and other precoder construction information in the first portion of the CSI feedback; and if RI > 4, provide feedback including a wideband CQI for a second transport block and a subband CQI for a second transport block, and a precoder generated according to the bitmap in the second portion of the CSI feedback.

[0110] The ninth embodiment may include any one or more embodiments of the first to eighth embodiments, wherein the size of the bitmap is the number of subbands at the highest indexed precoding level, including both trimmed and untrimmed subbands.

[0111] The tenth embodiment may include any one or more embodiments of the first to ninth embodiments, wherein the processor is further configured to: determine a precoder at one or more hierarchical precoding levels based on at least one of the following: N tx xR or N tx xR1, where N tx Includes the CSI-RS port number, and R includes the feedback rank indicator (RI), and R1 is greater than R.

[0112] The eleventh embodiment may include any one or more embodiments of the first to tenth embodiments, wherein the processor is further configured to generate a hierarchical precoding scheme based on an overhead reduction mechanism, the overhead reduction mechanism including feedback overhead of CSI feedback in hierarchical precoding levels that distinguish precoding hierarchical structures.

[0113] The twelfth embodiment may include any one or more embodiments of the first to eleventh embodiments, wherein the feedback overhead in the hierarchical precoding hierarchy is less at the higher index hierarchical precoding level of the precoding hierarchy than at the lower index hierarchical precoding level of the precoding hierarchy.

[0114] The thirteenth embodiment may include any one or more embodiments of the first to twelfth embodiments, wherein the processor is further configured to: trim one or more hierarchical precoding levels of frequency portions or subbands based on an overhead reduction mechanism for CSI feedback; and generate bitmaps indicating untrimmed and trimmed subbands associated with CSI feedback.

[0115] The fourteenth embodiment may include any one or more embodiments of the first to thirteenth embodiments, wherein the processor is further configured to: determine different divisions of the frequency portion of the frequency band based on a predetermined size, or adapt the size of the different divisions to the parent frequency portion of a lower index hierarchy level, such that approximately equal portions of the different divisions are allocated to subband divisions of a higher index hierarchy level for the hierarchical precoding scheme.

[0116] The fifteenth embodiment may include any one or more embodiments of the first to fourteenth embodiments, wherein the processor is further configured to: generate a precoder codebook having a precoder for CSI feedback, the precoder codebook including a resolution of rotation angles that are progressively coarser at lower index hierarchical precoding levels compared to higher index hierarchical precoding levels that include frequency portions or subbands of frequency bands for hierarchical precoding schemes.

[0117] The sixteenth embodiment may include any one or more embodiments of the first to fifteenth embodiments, wherein the processor is further configured to: generate CSI feedback based on omission rules, wherein the omission rules include: the feedback overhead in response to the CSI feedback does not exceed a resource limit derived from at least one of network configuration or network signaling; the CSI feedback includes one or more precoders of CSI feedback from the lowest indexed hierarchical precoding level to the highest indexed hierarchical precoding level; and generate CSI feedback based on omission rules for omitting one or more precoders at the highest indexed hierarchical precoding level or at a hierarchical precoding level higher than the lowest indexed hierarchical precoding level, the CSI feedback including feedback corresponding to the frequency portions of unpruned subbands from the lowest indexed hierarchical precoding level to the highest indexed hierarchical precoding level, and increasing with the indexing of frequency portions at the same hierarchical precoding level until a resource limit is reached.

[0118] The seventeenth embodiment may include any one or more embodiments of the first to sixteenth embodiments, wherein the processor is further configured to: provide feedback including one or more of the following: a CSI-RS resource indicator (CRI), a rank indicator (RI), a wideband channel quality indicator (CQI) for a first transport block, a subband CQI for a first transport block having an ascending order of subband indices, wherein a bitmap indicates unpruned and pruned subbands among subbands of the highest index-level precoding level; and other precoder construction information in the first portion of the CSI feedback; and if RI > 4, provide feedback including a wideband CQI for a second transport block and a subband CQI for a second transport block, and one or more precoders generated from a bitmap in the second portion of the CSI feedback.

[0119] The eighteenth embodiment may include any one or more embodiments of the first to seventeenth embodiments, wherein the processor is further configured to: average one or more parameters based on frequencies within a sub-band range of a frequency portion associated with the frequency band; and apply the one or more parameters across one or more hierarchical precoding levels of a hierarchical precoding scheme.

[0120] The ninth embodiment is a tangible computer-readable storage device that stores executable instructions that, in response to execution, cause one or more processors of a user equipment (UE) to perform operations including: receiving a channel state information reference signal (CSI-RS) within one or more orthogonal frequency division multiplexing (OFDM) symbols; and generating channel state information (CSI) feedback based on a hierarchical precoding scheme that selectively reduces feedback overhead associated with the CSI feedback.

[0121] The twentieth embodiment may include the nineteenth embodiment, wherein these operations further include: subdividing the frequency band of the hierarchical precoding level into frequency portions at one or more lower hierarchical levels.

[0122] The twenty-first embodiment may include any one or more embodiments of the nineteenth to twentieth embodiments, wherein these operations further include: subdividing frequency portions at one or more hierarchical levels into subbands to form a subtree of a precoding hierarchical structure, wherein these frequency portions include frequency portions of equal division of frequency bands, and these subbands include the highest indexed hierarchical precoding level for the hierarchical precoding scheme.

[0123] The twenty-second embodiment may include any one or more embodiments of the nineteenth to twenty-first embodiments, wherein these operations further include: in response to a CSI feedback exceeding the feedback payload limit, generating CSI feedback in two parts by providing a bitmap of subbands and further providing CSI feedback including a precoding matrix index (PMI) precoder based on a hierarchical precoding scheme, the bitmap of these subbands indicating which of these subbands are associated with the CSI feedback.

[0124] The twenty-third embodiment may include a baseband processor comprising: a memory; a processor configured to: receive a channel state information reference signal (CSI-RS) within one or more orthogonal frequency division multiplexing (OFDM) symbols; determine frequency portions of frequency bands and subbands from frequency portions to be configured at different hierarchical levels in a hierarchical precoding scheme that selectively reduces feedback overhead associated with channel state information (CSI) feedback; and generate CSI feedback based on a precoding hierarchy structure of the hierarchical precoding scheme.

[0125] The twenty-fourth embodiment may include the twenty-third embodiment, wherein the processor is further configured to prune the subtree of the precoding hierarchy structure formed from these subbands based on the precoder differences between frequency portions or subbands.

[0126] The twenty-fifth embodiment may be a next-generation node B (gNB), which includes: a memory; one or more processors configured to: transmit a channel state information reference signal (CSI-RS) for CSI feedback; and, in response to providing the CSI-RS, receive channel state information (CSI) feedback corresponding to one or more frequency portions of a hierarchical precoding level in the frequency band based on a hierarchical precoding scheme.

[0127] The twenty-sixth embodiment may include the twenty-fifth embodiment, wherein these hierarchical precoding levels include a highest indexed precoding level, which includes subbands subdivided from one or more frequency portions used in the hierarchical precoding scheme.

[0128] The twenty-seventh embodiment may include any one of the twenty-fifth to twenty-sixth embodiments, wherein the lowest index hierarchical precoding level includes a frequency band as a root frequency portion.

[0129] The twenty-eighth embodiment may include any one of the embodiments of the twenty-fifth to twenty-seventh embodiments, wherein the CSI feedback includes one or more bitmaps indicating unpruned subbands and one or more pruned subbands in the subbands and frequency portions of one or more hierarchical precoding levels in the hierarchical precoding hierarchy of the precoding hierarchy for the hierarchical precoding scheme.

[0130] The twenty-ninth embodiment may include any of the embodiments of the twenty-fifth to twenty-eighth embodiments, identifying unpruned subbands and one or more pruned subbands in the subbands and frequency portions of one or more hierarchical precoding levels of a hierarchical precoding scheme based on one or more bitmaps; mapping the precoder received from CSI feedback to one or more unpruned subbands in the unpruned subbands of one or more hierarchical precoding levels.

[0131] The thirtieth embodiment may include any one of the twenty-fifth to twenty-ninth embodiments, wherein the one or more processors are further configured to map the precoder received in the CSI feedback to a hierarchical precoding level of the frequency band.

[0132] The thirty-first embodiment may include any one of the twenty-fifth to thirtyth embodiments, wherein the one or more processors are further configured to determine the precoder based on a hierarchical precoding scheme and CSI feedback.

[0133] The thirty-second embodiment may include any one of the embodiments of the twenty-fifth to thirty-first embodiments, wherein the one or more processors are further configured to: determine which precoder locations to eliminate from the CSI feedback and the precoder locations at the hierarchical precoder level associated with the CSI feedback.

[0134] The thirty-third embodiment may include any one of the embodiments in the twenty-fifth to thirty-second embodiments, wherein the one or more processors are further configured to: map the precoder of the CSI feedback to a hierarchical tree structure in the hierarchical precoding level; and, based on the hierarchical precoding scheme, determine which subtrees of the hierarchical tree structure are pruned according to the CSI feedback, wherein these subtrees are derived from the frequency portion of the frequency band at the hierarchical precoding level.

[0135] The thirty-fourth embodiment may include any one of the twenty-fifth to thirty-third embodiments, wherein the one or more processors are further configured to: determine the feedback size based on one or more bitmaps for the second CSI feedback in response to the CSI feedback exceeding the payload limit.

[0136] The thirty-fifth embodiment may include any one of the twenty-fifth to thirty-fourth embodiments, wherein one or more precoders associated with CSI feedback are parameterized by one or more parameters that are functions of frequency and are averaged across subbands of one or more frequency portions used in the hierarchical precoding scheme.

[0137] The thirty-sixth embodiment may be a tangible computer-readable storage device storing executable instructions that, in response to execution, cause one or more processors of a network device, including an access point or a next-generation node B (gNB), to perform operations including: providing a channel state information reference signal (CSI-RS) for CSI feedback; and receiving CSI feedback of a frequency portion corresponding to a hierarchical precoding level of a broadband frequency based on a hierarchical precoding scheme.

[0138] The thirty-seventh embodiment may include the thirty-sixth embodiment, wherein these operations further include: determining which precoders corresponding to one or more frequency portions or one or more subbands of a hierarchical precoding level are associated with CSI feedback, so as to pair the CSI feedback with a physical channel for user equipment (UE).

[0139] The thirty-eighth embodiment may include any one of the thirty-sixth to thirty-seventh embodiments, wherein the precoder is configured based on the product of a first matrix and a second matrix for a hierarchical precoding level for a hierarchical precoding scheme, wherein the first matrix includes CSI-RS port numbers and the second matrix is ​​rank-dependent based on a feedback rank indicator (RI).

[0140] The thirty-ninth embodiment may include any one of the embodiments in the thirty-sixth to thirty-eighth embodiments, wherein these operations further include: determining one or more bitmaps corresponding to hierarchical precoding levels based on a bottom-up approach, the bottom-up approach starting from the highest index hierarchical level, the highest index hierarchical level including the frequency portion within the subtree branch division of the subband derived from the root frequency portion.

[0141] The fortieth embodiment may include any one of the thirty-sixth to thirty-ninth embodiments, wherein these operations further include: providing a payload limit associated with the CSI feedback; and in response to the CSI feedback exceeding the payload limit: receiving a bitmap indicating one or more precoders associated with the CSI feedback and other precoders omitted from the CSI feedback in response to the CSI feedback exceeding the payload limit; and receiving a second CSI feedback according to the payload size indicated by the bitmap.

[0142] The forty-first embodiment may include any one of the embodiments in the thirty-sixth to fortieth embodiments, wherein the feedback overhead in the hierarchical precoding level is less in the higher index hierarchical precoding level than in the higher hierarchical precoding level with a lower feedback priority and a precoding hierarchy structure.

[0143] The forty-second embodiment may be a baseband processor, which includes: a memory; processing circuitry configured to: provide a channel state information reference signal (CSI-RS) for CSI feedback; and receive channel state information (CSI) feedback corresponding to one or more frequency portions of a frequency band based on a hierarchical precoding scheme.

[0144] The forty-third embodiment may include the forty-second embodiment, wherein the processing circuitry is further configured to: determine, based on one or more bitmaps corresponding to hierarchical precoding levels, which precoders are associated with CSI feedback and which precoders are omitted from CSI feedback.

[0145] The forty-fourth embodiment may include any one of the forty-two to forty-three embodiments, wherein the processing circuitry is further configured to: receive a bitmap in response to the CSI feedback exceeding a payload limit, the bitmap indicating one or more precoders associated with the CSI feedback and other precoders omitted from the CSI feedback in response to the CSI feedback exceeding a payload limit; and receive a second CSI feedback according to the payload size indicated by the bitmap.

[0146] Furthermore, standard programming and / or engineering techniques can be used to implement the various aspects or features described herein as methods, apparatus, or articles of art. As used herein, the term "article of art" is intended to cover a computer program accessible from any computer-readable device, carrier, or medium. For example, computer-readable media may include, but is not limited to, magnetic storage devices (e.g., hard disks, floppy disks, magnetic stripes), optical discs (e.g., high-density disks (CDs), digital versatile disks (DVDs), etc.), smart cards, and flash memory devices (e.g., EPROMs, cards, sticks, key drives, etc.). Additionally, the various storage media described herein may represent one or more devices and / or other machine-readable media for storing information. The term "machine-readable medium" may include, but is not limited to, wireless channels and various other media capable of storing, containing, and / or carrying instructions and / or data. Furthermore, a computer program product may include a computer-readable medium having one or more instructions or codes that are operable to cause a computer to perform the functions described herein.

[0147] Communication media embody computer-readable instructions, data structures, program modules, or other structured or unstructured data in data signals such as modulated data signals, such as carrier waves or other transmission mechanisms, and include any information delivery or transmission medium. The term "modulated data signal" or signal refers to a signal whose one or more characteristics are set or altered in a manner that encodes information in one or more signals. By way of example, and not limitation, communication media include wired media such as wired networks or direct wired connections, and wireless media such as acoustic, RF, infrared, and other wireless media.

[0148] An exemplary storage medium can be coupled to a processor, enabling the processor to read information from and write information to the storage medium. Alternatively, the storage medium can be integrated with the processor. Furthermore, in some aspects, the processor and storage medium can reside in an ASIC. Additionally, the ASIC can reside in a user terminal. Alternatively, the processor and storage medium can reside as discrete components in the user terminal. Furthermore, in some aspects, the process and / or actions of a method or algorithm can reside as one or any combination or set of code and / or instructions on a machine-readable and / or computer-readable medium, and can be incorporated into a computer program product.

[0149] In this regard, although the subject matter disclosed herein has been described in conjunction with various embodiments and corresponding drawings, it should be understood that other similar embodiments may be used, or modifications and additions may be made to the described embodiments, to perform the same, similar, alternative, or substitute functions of the disclosed subject matter without departing from the described embodiments. Therefore, the disclosed subject matter should not be limited to any single embodiment described herein, but should be interpreted in accordance with the breadth and scope of the following appended claims.

[0150] In particular, regarding the various functions performed by the aforementioned components (components, devices, circuits, systems, etc.), unless otherwise stated, the terminology used to describe such components (including references to "means") is intended to correspond to any component or structure that performs the specified function of the said component (e.g., functionally equivalent), even if it is not structurally equivalent to the disclosed structure that performs the function in the exemplary embodiments of this disclosure shown herein. Furthermore, while certain features have been disclosed with respect to only one of several embodiments, it may be desirable and advantageous for any given or particular application to combine such features with one or more other features of other embodiments.

Claims

1. A base station, comprising: Memory; One or more processors, said one or more processors being configured to: Transmit the Channel State Information Reference Signal (CSI-RS) for Channel State Information (CSI) feedback; as well as In response to providing the CSI-RS, the CSI feedback corresponding to one or more frequency portions of a hierarchical precoding level within a frequency band is received based on a hierarchical precoding scheme, the hierarchical precoding scheme including a precoder W having a precoder for the CSI feedback. h,m The precoder codebook includes a resolution of rotation angles that are progressively coarser at lower index-level precoder levels compared to higher index-level precoder levels that include one or more frequency portions of the frequency band.

2. The base station of claim 1, wherein the hierarchical precoding level includes a highest index precoding level, the highest index precoding level including subbands subdivided from the one or more frequency portions used for the hierarchical precoding scheme.

3. The base station according to claim 1, wherein the lowest index hierarchical precoding level of the hierarchical precoding level includes the frequency band as a root frequency portion.

4. The base station of claim 1, wherein the CSI feedback comprises one or more bitmaps indicating subbands of one or more hierarchical precoding levels in the hierarchical precoding hierarchy of the hierarchical precoding scheme and unpruned subbands and one or more pruned subbands in the one or more frequency portions.

5. The base station according to claim 4, wherein the one or more processors are further configured to: Identify, based on the one or more bitmaps, the unpruned subbands and the one or more pruned subbands among the subbands and the one or more frequency portions of the one or more hierarchical precoding levels of the hierarchical precoding scheme; and The precoder received from the CSI feedback is mapped to one or more unpruned subbands at the one or more hierarchical precoder levels.

6. The base station according to claim 1, wherein the one or more processors are further configured to: The precoder received in the CSI feedback is mapped to the hierarchical precoding level of the frequency band.

7. The base station according to claim 1, wherein the one or more processors are further configured to: The precoder is determined from the CSI feedback based on the hierarchical precoding scheme.

8. The base station according to claim 1, wherein the one or more processors are further configured to: Determine which precoder locations to eliminate from the CSI feedback and the precoder locations associated with the CSI feedback at the hierarchical precoder level.

9. The base station according to claim 1, wherein the one or more processors are further configured to: Map the precoder that receives the CSI feedback to the hierarchical tree structure of the hierarchical precoder level; and Based on the hierarchical precoding scheme, the CSI feedback determines which subtrees of the hierarchical tree structure are pruned, wherein the subtrees are derived from one or more frequency portions of the frequency band at the hierarchical precoding level.

10. The base station of claim 9, wherein the one or more processors are further configured to: In response to the CSI feedback, which serves as the first CSI feedback, exceeding the payload limit, the feedback size is determined based on one or more bitmaps used for the second CSI feedback.

11. The base station of claim 1, wherein one or more precoders associated with the CSI feedback are parameterized by one or more parameters, the one or more parameters being a function of frequency and averaged over subbands of the one or more frequency portions of the hierarchical precoding scheme.

12. A tangible computer-readable storage device storing executable instructions that, in response to execution, cause one or more processors of a network device to perform operations, the operations including: Provides a Channel State Information Reference Signal (CSI-RS) for Channel State Information (CSI) feedback; as well as The CSI feedback is received based on a hierarchical precoding scheme corresponding to the frequency portion of a hierarchical precoding level for a wideband frequency, the hierarchical precoding scheme including a precoder W for the CSI feedback. h,m The precoder codebook includes a resolution of rotation angles that are progressively coarser at lower index-level precoder levels compared to higher index-level precoder levels that include one or more frequency portions of the frequency band.

13. The tangible computer-readable storage device of claim 12, wherein the operation further comprises: Determine which precoders corresponding to one or more frequency portions or one or more subbands of the hierarchical precoding level are associated with the CSI feedback, so as to pair the CSI feedback with a physical channel for user equipment (UE).

14. The tangible computer-readable storage device of claim 13, wherein the precoder is configured based on the product of a first matrix and a second matrix for the hierarchical precoding level of the hierarchical precoding scheme, wherein the first matrix includes a CSI-RS port number and the second matrix is ​​rank-dependent based on a feedback rank indicator (RI).

15. The tangible computer-readable storage device of claim 12, wherein the operation further comprises: One or more bitmaps corresponding to the hierarchical precoding levels are determined using a bottom-up approach, starting from the highest index hierarchical level, which includes the frequency portion within the subtree branch division of the subband derived from the root frequency portion.

16. The tangible computer-readable storage device of claim 12, wherein the operation further comprises: Provide a payload limit associated with the CSI feedback; as well as In response to the CSI feedback exceeding the payload limit: Receive a bitmap indicating one or more precoders associated with the CSI feedback and other precoders omitted from the CSI feedback in response to the CSI feedback exceeding the payload limit; as well as The second CSI feedback is received based on the payload size indicated by the bitmap.

17. The tangible computer-readable storage device of claim 12, wherein the feedback overhead in the hierarchical precoding levels is less in higher indexed hierarchical precoding levels than in higher hierarchical precoding levels with lower feedback priorities having a precoding hierarchy.

18. A baseband processor, comprising: Memory; Processing circuit, the processing circuit being configured to: Provides a Channel State Information Reference Signal (CSI-RS) for Channel State Information (CSI) feedback; as well as The CSI feedback is received based on a hierarchical precoding scheme corresponding to one or more frequency portions of a frequency band, the hierarchical precoding scheme including a precoder W for the CSI feedback. h,m The precoder codebook includes a resolution of rotation angles that are progressively coarser at lower index-level precoder levels compared to higher index-level precoder levels that include one or more frequency portions of the frequency band.

19. The baseband processor of claim 18, wherein the processing circuitry is further configured to: Based on one or more bitmaps corresponding to hierarchical precoding levels, determine which precoders are associated with the CSI feedback and which precoders are omitted from the CSI feedback.

20. The baseband processor of claim 18, wherein the processing circuitry is further configured to: In response to the CSI feedback exceeding the payload limit: Receive a bitmap indicating one or more precoders associated with the CSI feedback and other precoders omitted from the CSI feedback in response to the CSI feedback exceeding the payload limit; and The second CSI feedback is received based on the payload size indicated by the bitmap.

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