Mapping the Windowed FD Basis to a Combined Indicator for PMI Reporting and Use

Abstract

The UE determines the PMI by performing at least the following operations: determining an intermediate set of vectors from an FD codebook; forming a subset of the intermediate set of vectors; mapping the vector subset to a combination indicator; and forming the PMI from at least the combination indicator. The UE transmits the PMI towards the radio network. The base station receives the PMI from the UE. The PMI includes a combination indicator that is mapped to a vector subset from the FD codebook. The base station uses at least the received PMI to determine information from at least the FD codebook to apply to data for transmission towards the UE.

Description

Field of the Invention

[0001] The present invention generally relates to feedback in a wireless communication system, and more particularly, to precoder matrix indication (PMI) and similar feedback. Background of the Invention

[0002] In a wireless communication system and particularly in a cellular system, channel state information (CSI) is determined by a user equipment (UE), and some indication corresponding to the CSI is fed back from the UE to the wireless network. One such indication is precoder matrix indication (PMI), which allows the wireless network to select information from a codebook and apply that information to data to be transmitted to the UE.

[0003] Recently, a new codebook and PMI feedback process has been proposed. Under this new scheme, there are certain problems with the selection and reporting of PMI, as described in more detail below. Brief Description of the Drawings

[0004] In the drawings:

[0005] Figure 1 is a block diagram of one possible and non - limiting exemplary system in which exemplary embodiments may be practiced;

[0006] Figure 2 is a logic flow diagram for channel state information feedback and use according to an exemplary embodiment, and shows the operations of one or more exemplary methods, the execution result of computer program instructions embodied on a computer - readable memory, the functions executed by logic implemented in hardware, and / or the interconnected means for performing the functions;

[0007] Figure 3 shows uplink control information (UCI) associated with enhanced type II PMI (precoder matrix indication) reporting for layer l according to an exemplary embodiment;

[0008] Figure 4 shows a graphical example of a sliding window mechanism using FD codebook indices (0 to 21) in the frequency domain and a corresponding mapping with a window of size 2M = 14 and an initial point of M 初始 = - 6;

[0009] Figure 5 shows, according to an exemplary embodiment, when applying the sliding window mechanism (e.g., N3>19 in the exemplary embodiment), the operations performed by a UE involved in mapping an FD base subset to a combined indication i l ; and

[0010] Figure 6A flowchart of a method for mapping a windowed FD basis to a combined indication for PMI reporting and use, performed by a network node according to an exemplary embodiment, and shows operations of one or more exemplary methods, results of execution of computer program instructions embodied on a computer-readable memory, functions performed by logic implemented in hardware, and / or interconnected means for performing the functions. SUMMARY OF THE INVENTION

[0011] This section is intended to include examples and is not intended to be limiting.

[0012] In an exemplary embodiment, a method is disclosed. The method includes determining a precoding matrix indicator by a user equipment. Determining the precoding matrix indicator includes: determining an intermediate set of vectors from a frequency-domain codebook, forming a subset of the intermediate set of vectors, mapping the subset of vectors to a combined indication, and forming the precoding matrix indicator at least from the combined indication. The method further includes transmitting the precoding matrix indicator from the user equipment towards a wireless network.

[0013] Additional exemplary embodiments include a computer program including code for performing the method of the previous paragraph when the computer program runs on a processor. According to the computer program of this paragraph, wherein the computer program is a computer program product, the computer program product includes a computer-readable medium carrying the computer program code for use with a computer. Another example is the computer program according to this paragraph, wherein the program can be directly loaded into the internal memory of a computer.

[0014] Exemplary apparatus includes one or more processors and one or more memories, the one or more memories including computer program code. The one or more memories and the computer program code are configured to, using the one or more processors, cause the apparatus to perform operations including: determining a precoding matrix indicator by a user equipment, including: determining an intermediate set of vectors from a frequency-domain codebook; forming a subset of the intermediate set of vectors; mapping the subset of vectors to a combined indication; and forming the precoding matrix indicator at least from the combined indication; and transmitting the precoding matrix indicator from the user equipment towards a wireless network.

[0015] Exemplary computer program products include a computer-readable storage medium carrying the computer program code for use with a computer, embodied therein. The computer program code includes: code for determining a precoding matrix indicator by a user equipment, including: determining an intermediate set of vectors from a frequency-domain codebook; forming a subset of the intermediate set of vectors; mapping the subset of vectors to a combined indication; and forming the precoding matrix indicator at least from the combined indication; and code for transmitting the precoding matrix indicator from the user equipment towards a wireless network.

[0016] In another exemplary embodiment, a device includes means for performing the following operations: determining, by a user equipment, a precoding matrix indicator, including: determining an intermediate set of vectors from a frequency-domain codebook; forming a subset of the intermediate set of vectors; mapping the vector subset to a combined indicator; and forming the precoding matrix indicator from at least the combined indicator; and transmitting, by the user equipment, the precoding matrix indicator towards a wireless network.

[0017] In an exemplary embodiment, a method is disclosed that includes receiving, at a base station, a precoding matrix indicator from a user equipment. The precoding matrix indicator includes a combined indicator mapped to a subset of vectors from a frequency-domain codebook. The method further includes using at least the received precoding matrix indicator to determine information from at least the frequency-domain codebook to apply to data for transmission towards the user equipment.

[0018] Additional exemplary embodiments include a computer program that includes code for performing the method of the previous paragraph when the computer program is run on a processor. A computer program according to this paragraph, wherein the computer program is a computer program product that includes a computer-readable medium having computer program code embodied therein for use with a computer. Another example is a computer program according to this paragraph, wherein the program can be directly loaded into the internal memory of a computer.

[0019] An exemplary device includes one or more processors and one or more memories, the one or more memories including computer program code. The one or more memories and the computer program code are configured to, using the one or more processors, cause the device to perform operations including: receiving, at a base station, a precoding matrix indicator from a user equipment, the precoding matrix indicator including a combined indicator mapped to a subset of vectors from a frequency-domain codebook; and using at least the received precoding matrix indicator to determine information from at least the frequency-domain codebook to apply to data for transmission towards the user equipment.

[0020] An exemplary computer program product includes a computer-readable storage medium having computer program code embodied therein for use with a computer. The computer program code includes: code for receiving, at a base station, a precoding matrix indicator from a user equipment, the precoding matrix indicator including a combined indicator mapped to a subset of vectors from a frequency-domain codebook; and code for using at least the received precoding matrix indicator to determine information from at least the frequency-domain codebook to apply to data for transmission towards the user equipment.

[0021] In another exemplary embodiment, a device includes means for performing the following operations: receiving, at a base station, a precoding matrix indicator from a user equipment, the precoding matrix indicator including a combined indicator mapped to a subset of vectors from a frequency-domain codebook; and determining, using at least the received precoding matrix indicator, information from at least the frequency-domain codebook to apply to data for transmission towards the user equipment. Detailed Description

[0022] The following abbreviations, which can be found in the specification and / or the drawings, are defined as follows:

[0023] 3GPP Third Generation Partnership Project

[0024] 5G Fifth Generation

[0025] 5GC 5G Core Network

[0026] AMF Access and Mobility Management Function

[0027] CSI Channel State Information

[0028] CU Central Unit

[0029] DU Distributed Unit

[0030] eNB (or eNodeB) Evolved Node B (e.g., an LTE base station)

[0031] EN-DC E-UTRA-NR Dual Connectivity

[0032] en-gNB or a node that provides NR user plane and control plane protocol termination towards the UE and

[0033] En-gNB A node that acts as a secondary node in EN-DC

[0034] E-UTRA Evolved Universal Terrestrial Radio Access, i.e., LTE radio access technology

[0035] FD Frequency Domain

[0036] gNB (or 5G / NR base station, i.e., a node that provides NR user plane and control

[0037] gNodeB) plane protocol termination and is connected to the 5GC via the NG interface

[0038] I / F Interface

[0039] LTE Long Term Evolution

[0040] MAC Media Access Control

[0041] MME Mobility Management Entity

[0042] ng or NG Next Generation

[0043] ng-eNB or NG-eNB Next Generation eNB

[0044] NR New Radio

[0045] N / W or NW Network

[0046] NZC Non-Zero Coefficient

[0047] PDCP Packet Data Convergence Protocol

[0048] PHY Physical Layer

[0049] PMI Precoder Matrix Indicator

[0050] RA Reference Amplitude

[0051] RAN Radio Access Network

[0052] Rel Release

[0053] RLC Radio Link Control

[0054] RRH Remote Radio Head

[0055] RRC Radio Resource Control

[0056] RU Radio Unit

[0057] Rx Receiver

[0058] SCI Strongest Coefficient Indicator

[0059] SD Spatial Domain

[0060] SDAP Service Data Adaptation Protocol

[0061] SGW Serving Gateway

[0062] SMF Session Management Function

[0063] TS Technical Specification

[0064] Tx Transmitter

[0065] UCI Uplink Control Information

[0066] UE User Equipment (e.g., a wireless device, typically a mobile device)

[0067] UPF User Plane Function

[0068] The term "exemplary" is used herein to mean "serving as an example, instance, or illustration". Any embodiment described herein as "exemplary" is not necessarily to be construed as preferred or advantageous over other embodiments. All embodiments described in this detailed description are exemplary embodiments provided to enable those skilled in the art to make or use the invention and not to limit the scope of the invention as defined by the claims.

[0069] Exemplary embodiments herein describe techniques for mapping a windowed FD basis to a combined indication for PMI reporting and use. Additional descriptions of these techniques are presented after a system where exemplary embodiments can be used is described.

[0070] Turning Figure 1 , the figure shows a block diagram of one possible and non - limiting exemplary system in which exemplary embodiments may be practiced. A user equipment (UE) 110, a radio access network (RAN) node 170, and a network element 190 are shown. In Figure 1 , the user equipment (UE) 110 communicates wirelessly with a wireless network 100. The UE is a wireless device that can access the wireless network, typically a mobile device. The UE 110 includes one or more processors 120, one or more memories 125, and one or more transceivers 130 interconnected by one or more buses 127. Each of the one or more transceivers 130 includes a receiver Rx 132 and a transmitter Tx 133. The one or more buses 127 can be an address bus, a data bus, or a control bus and can include any interconnect mechanism such as a series of lines on a motherboard or integrated circuit, optical fibers, or other optical communication devices, etc. The one or more transceivers 130 are connected to one or more antennas 128. The one or more memories 125 include computer program code 123. The UE 110 includes a control module 140, and the control module includes one or both of parts 140 - 1 and / or 140 - 2 that can be implemented in several ways. The control module 140 can be implemented in hardware as control module 140 - 1, such as being implemented as part of one or more processors 120. The control module 140 - 1 can also be implemented as an integrated circuit or by other hardware such as a programmable gate array. In another example, the control module 140 can be implemented as control module 140 - 2, which is implemented as computer program code 123 and executed by one or more processors 120. For example, the one or more memories 125 and the computer program code 123 can be configured to cause the user equipment 110 to perform one or more of the operations described herein using one or more processors 120. The UE 110 communicates with the RAN node 170 via a wireless link 111.

[0071] The RAN node 170 is a base station that provides access to the wireless network 100 for wireless devices such as the UE 110. For example, the RAN node 170 may be a base station for 5G, also known as New Radio (NR). In 5G, the RAN node 170 may be an NG-RAN node, which is defined as a gNB or an ng-eNB. A gNB is a node that provides NR user plane and control plane protocol termination towards the UE and is connected to the 5GC (e.g., the network element 190) via the NG interface. An ng-eNB is a node that provides E-UTRA user plane and control plane protocol termination towards the UE and is connected to the 5GC via the NG interface. The NG-RAN node may include multiple gNBs, and the multiple gNBs may further include a Central Unit (CU) (gNB-CU) 196 and a Distributed Unit (DU) (gNB-DU), where the DU 195 is shown. It should be noted that the DU may include or be coupled to and control a Radio Unit (RU). The gNB-CU is a logical node that hosts the RRC, SDAP, and PDCP protocols of the gNB or controls the operation of one or more gNB-DUs, and the RRC and PDCP protocols of the en-gNB. The gNB-CU terminates the F1 interface connected to the gNB-DU. The F1 interface is shown as the reference numeral 198, although the reference numeral 198 also shows the link between the remote element and the centralized element of the RAN node 170, such as between the gNB-CU 196 and the gNB-DU 195. The gNB-DU is a logical node that hosts the RLC, MAC, and PHY layers of the gNB or en-gNB, and its operation is partially controlled by the gNB-CU. One gNB-CU supports one or more cells. One cell is supported by only one gNB-DU. The gNB-DU terminates the F1 interface 198 connected to the gNB-CU. It should be noted that the DU 195 is considered to include the transceiver 160, for example, as part of the RU, but some examples in this regard may make the transceiver 160 part of a separate RU, for example, under the control of the DU 195 and connected to the DU 195. The RAN node 170 may also be an eNB (evolved NodeB) base station for LTE (Long-Term Evolution), or any other suitable base station.

[0072] The RAN node 170 includes one or more processors 152, one or more memories 155, one or more network interfaces (N / W I / F) 161, and one or more transceivers 160 interconnected by one or more buses 157. Each of the one or more transceivers 160 includes a receiver Rx 162 and a transmitter Tx 163. The one or more transceivers 160 are connected to one or more antennas 158. The one or more memories 155 include computer program code 153. The CU 196 may include the processor 152, the memory 155, and the network interface 161. It should be noted that the DU 195 may also include its own one or more memories and processors, and / or other hardware, but these are not shown.

[0073] The RAN node 170 includes a control module 150, and the control module includes one or both of parts 150-1 and / or 150-2 that can be implemented in several ways. The control module 150 can be implemented in hardware as the control module 150-1, such as being implemented as part of one or more processors 152. The control module 150-1 can also be implemented as an integrated circuit or by other hardware such as a programmable gate array. In another example, the control module 150 can be implemented as the control module 150-2, which is implemented as computer program code 153 and executed by one or more processors 152. For example, the one or more memories 155 and the computer program code 153 are configured to cause the RAN node 170 to perform one or more of the operations described herein using one or more processors 152. It should be noted that the functionality of the control module 150 may be distributed, such as being distributed between the DU 195 and the CU 196, or being implemented separately in the DU 195.

[0074] One or more network interfaces 161 communicate via a network, such as via links 176 and 131. Two or more RAN nodes 170 communicate using, for example, the link 176. The link 176 can be wired or wireless or both, and can implement, for example, the Xn interface for 5G, the X2 interface for LTE, or other suitable interfaces for other standards.

[0075] One or more buses 157 can be an address bus, a data bus, or a control bus and can include any interconnection mechanism, such as a series of lines on a motherboard or integrated circuit, fiber optic or other optical communication devices, wireless channels, etc. For example, one or more transceivers 160 can be implemented as a remote radio head (RRH) 195 for LTE or a distributed unit (DU) 195 for a gNB implementation for 5G, where other elements of the RAN node 170 may be physically located at a different location from the RRH / DU, and one or more buses 157 can be partially implemented as, for example, a fiber optic cable or other suitable network connection to connect other elements of the RAN node 170 (e.g., a central unit (CU), gNB-CU) to the RRH / DU 195. Reference numeral 198 also indicates those suitable network links.

[0076] The wireless network 100 can include one or more network elements 190, which can include core network functionality and provide connectivity to other networks such as a telephone network and / or a data communication network (e.g., the Internet) via one or more links 181. Such core network functionality for 5G can include an access and mobility management function (AMF) and / or a user plane function (UPF) and / or a session management function (SMF). Such core network functionality for LTE can include MME (mobility management entity) / SGW (serving gateway) functionality. These are only example functions that can be supported by the network element 190, and it should be noted that both 5G and LTE functions can be supported. The RAN node 170 is coupled to the network element 190 via a link 131. The link 131 can be implemented as, for example, an NG interface for 5G, or an S1 interface for LTE, or other suitable interfaces for other standards. The network element 190 includes one or more processors 175, one or more memories 171, and one or more network interfaces (N / W I / F) 180 interconnected by one or more buses 185. One or more memories 171 include computer program code 173. One or more memories 171 and the computer program code 173 are configured to cause the network element 190 to perform one or more operations using one or more processors 175.

[0077] The wireless network 100 enables network virtualization, which is the process of combining hardware and software network resources and network functionality into a single software-based management entity (i.e., a virtual network). Network virtualization involves platform virtualization and is typically combined with resource virtualization. Network virtualization is divided into: external network virtualization, which combines many networks or parts of networks into virtual units; or internal network virtualization, which provides network-like functionality to software containers on a single system. It should be noted that the virtualized entities resulting from network virtualization are still implemented to some extent using hardware such as processors 152 or 175 and memories 155 and 171, and such virtualized entities also produce technical effects.

[0078] The computer-readable memories 125, 155, and 171 can be of any type suitable for the local technical environment and can be implemented using any suitable data storage technology, such as semiconductor-based memory devices, flash memories, magnetic memory devices and systems, optical memory devices and systems, fixed memories, and removable memories. The computer-readable memories 125, 155, and 171 may be devices for performing storage functions. As a non-limiting example, the processors 120, 152, and 175 can be of any type suitable for the local technical environment and can include one or more of the following: general-purpose computers, special-purpose computers, microprocessors, digital signal processors (DSPs), and processors based on multi-core processor architectures. The processors 120, 152, and 175 may be devices for performing functions such as controlling the UE 110, the RAN node 170, and other functions as described herein.

[0079] Generally, various embodiments of the user equipment 110 can include, but are not limited to, cellular phones such as smart phones, tablet computers, personal digital assistants (PDAs) with wireless communication capabilities, portable computers with wireless communication capabilities, vehicles with modem devices for wireless V2X (vehicle-to-everything) communication, image capture devices with wireless communication capabilities such as digital cameras, game devices with wireless communication capabilities, music storage and playback devices with wireless communication capabilities, Internet devices (including Internet of Things (IoT) devices) that allow wireless Internet access and possibly browsing, IoT devices with sensors and / or actuators that use wireless communication for automation applications, tablet computers with wireless communication capabilities, and portable units or terminals incorporating combinations of such functions.

[0080] An appropriate but non-limiting technical background for practicing the exemplary embodiments of the present invention has thus been presented, and the exemplary embodiments will now be described more specifically.

[0081] Figure 2It is a signaling and logic flow diagram for channel state information feedback and usage. The figure also shows the operations of one or more exemplary methods according to an exemplary embodiment, the execution results of computer program instructions embodied on a computer-readable memory, the functions executed by logic implemented in hardware, and / or the interconnected devices for performing the functions. For example, the control module 140 for the UE 110 and the control module 150 for the RAN node 170 may include Figure 2 multiple blocks therein, where each included block is an interconnected device for performing the functions in the block. Assume Figure 2 the blocks in are executed by the UE 110, for example, at least partially under the control of the control module 140, or by the RAN node 170, for example, at least partially under the control of the control module 150.

[0082] In step 1, the RAN node 170 transmits a reference signal to the UE 110. In step 2, the UE uses the reference signal to determine the channel state information (CSI) (including PMI). In step 3, the UE 110 uses the determined channel state information to determine the feedback information (including PMI). In step 4, the UE 110 feeds back the determined feedback information (including PMI). This information is typically fed back using one or more CSI reports 210.

[0083] In response to receiving the feedback information, the RAN node 170 determines the precoding to be used (e.g., one or more matrices) at least based on the PMI in step 5. In step 6, the RAN node 170 applies the determined precoding to the data to be transmitted to the UE, and in step 7, transmits the precoded data towards the UE. In step 8, the UE 110 processes the received precoded data.

[0084] It should be noted that in the remainder of this disclosure, the RAN node 170 is referred to as a gNB. As described above, this is not a limitation, and the RAN node 170 may be other elements, such as an eNB.

[0085] Figure 2 A simple overview of channel state information (such as PMI, reporting, and usage) is presented. The exemplary embodiments herein relate to PMI determination and reporting. First, an introduction to the technical field of PMI determination and reporting is provided, and then the overview and exemplary embodiments are described in detail.

[0086] As an introduction, in Rel-16 type-II precoder matrix indicator (PMI) feedback, a new codebook has been introduced that compresses channel state information (CSI) across N3 of the PMI sub-bands, where each sub-band has a PMI determined for it. A subset M of the N3 elements is selected from this frequency domain (FD) codebook, where M < N3, to form the basis of the orthogonal vectors signaled from UE 110 to gNB 170 as part of the CSI report 210. Each codebook element is indicated by an index with an alphabet set: {0, 1,..., N3 - 1}, where N3 is the codebook size, which corresponds to the number of PMI sub-bands. In an example implementation, the indices of the M basis vectors, i.e., the FD basis subset, are reported from UE 110 to gNB 170.

[0087] In RAN1#97, a sliding window mechanism was introduced to simplify the signaling of this FD basis subset for a large number of PMI sub-bands (e.g., such as N3 > 1). See the protocol "CSI enhancement for MU-MIMO support", section 7.2.8.1 in 3GPP "RAN1 Chairman's Notes RAN1#97" in Reno, USA, May 2019. The window is applied to the codebook indices such that only the indices within the window can be reported. This operation constrains the reportable codebook index alphabet set from N3 to L possible values, which corresponds to a window of size L. In an example implementation, L = 2M. The sliding window is parameterized by its starting point M 初始 which is signaled as part of the CSI report 310.

[0088] It was also agreed that, assuming L = 2M and the first element is always 0 (zero), for N3 > 19, the FD basis subset is indicated by a combined indicator with a bit width of The mapping from the basis index subset to the combined indicator has not been specified in the protocol. This mapping presents a problem that will be detailed below and the exemplary implementations in this document provide solutions for this.

[0089] Regarding the exemplary problem, consider the M combinations of the frequency domain (FD) components of the foreshadowing layers l = 1,..., υ, where the vector notation of their indices is

[0090]

[0091] where the elements of the combination are selected from a codebook of N3 vectors and their indices are given by

[0092]

[0093] where f = 0, 1,..., M - 1.

[0094] The M codebook vectors are indicated by the index i l (l = 1, ..., υ), where

[0095]

[0096] It should be noted that the example of equation (3) is for N3 > 19 and L = 2M, although this is only an example.

[0097] In this case, we may want to indicate the (M - 1)-combinations of the elements, since the codebook index of n 3，l is indicated relative to the FD component associated with the strongest coefficient indicated, since where mod is the modulo operator, and for all layers, the first element of the combination in equation (1) is and may not need to be reported. Thus, the combination indicator i l reports only M - 1 codebook elements and the number of possible combinations is given by the binomial assuming L = 2M.

[0098] Generally, i l is a combination index of degree M - 1 and number 2M - 1, which can map the (M - 1)-combinations to a set of at most 2M - 1 elements when N3 is large in some exemplary embodiments, e.g., when N3 > 19. The codebook elements are defined in the alphabet {1, 2, ..., N3 - 1} of size N3 - 1 > 2M - 1. Thus, in principle, a larger number of combination indicators than those defined in equation (3) would be needed to represent all possible (M - 1)-combinations of the codebook elements. However, a sliding window mechanism has been introduced such that only the non-zero elements and the initial point in a window of size 2M

[0099]

[0100] are reported. The sliding window is given by the following intermediate set:

[0101]

[0102] Therefore, IntS is a new set of constraints on the codebook elements, and the reported elements f = 1, 2, ... M - 1 can take any value in the alphabet of size 2M - 1 (the zero value is always in the window but may not need to be reported). It should be noted that the values in the set change with the parameter M 初始and change, and some selected values may be outside the range {1, 2,..., 2M - 1}. This will be described in more detail as follows. Figure 4 as described in more detail below.

[0103] To solve this problem, a mapping element is introduced in the exemplary embodiments herein. The notation IntS\{0} indicates that the value '0' is excluded from the set IntS. For example, a mapping function is introduced that allows the (M - 1)-combinations of the non-zero elements of the intermediate set IntS to be indicated by a combination indication of order M - 1 and quantity 2M - 1, identified by a sliding window of length 2M within a set of size N3 > 2M. It should be noted that without this mapping, a larger number N3 - 1 of combination indications would have to be used, which corresponds to a instead of larger index bit width.

[0104] In additional detail, the mapping from element to element is given in a compact form as follows:

[0105]

[0106] or as shown by the following equivalent expression:

[0107]

[0108] Another alternative and equivalent expression is given by the following:

[0109]

[0110] This operation allows the set of values IntS that changes with M 初始 to be mapped to the continuous set {0, 1, 2,..., 2M - 1} of 2M values. After applying this mapping, a ranking function can be introduced that determines the index i from the (M - 1)-combinations l . Since the combinations are represented as strictly decreasing sequences, for f = 1, 2,..., M - 1, a second mapping from to can be used such that This second mapping is given by the following:

[0111]

[0112] The combination indication i corresponding to the sequence lGiven by the following ranking function:

[0113]

[0114] where

[0115]

[0116] (10) now satisfies the definition in equation (3).

[0117] After defining the ranking function in equation (10), the deranking procedure is straightforward and follows a standard algorithm to find the sequence from index i l in from which the codebook elements can be found by reversing the mappings in equations (9) and (6), (7), or (8). The FD basis of An example of a standard algorithm can be found in Section 5.2.2.2.3 of 3GPP TS38.214 V15.6.0 (2019-06), but other algorithms can also be used.

[0118] In particular, the reciprocals of equations (6), (7), or (8) are given by

[0119]

[0120] The reciprocal of equation (9) is given by:

[0121]

[0122] Figure 3 Shows the uplink control information (UCI) associated with the enhanced type II PMI (precoder matrix indicator) report for layer l. In this figure, the following acronyms are used and defined: SD: spatial domain; SCI: strongest coefficient indicator; RA: reference amplitude; and NZC: non-zero coefficient. The PMI report 300 in this example includes a first part (part 1) 305 of fixed size and a second part (part 2) 310 of variable size. For example, the PMI report 300 may be part of the CSI report 210 sent in Figure 2 step 4 of The variable-size part 310 includes three groups, group 0, group 1, and group 2. Group 0 includes the following indicators: SD rotation, SD basis, and SCI. Group 1 includes the following indicators: FD basis, RA, bitmap, and NZC. Group 2 includes the following indicators: bitmap and NZC.

[0123] The frequency domain (FD) basis indicator includes the index i l and an additional indicator i 初始 for the parameter M init325. In some embodiments, an additional indication i init 325 is used for a large number of PMI sub - bands, such as N3 > 19, but this is not a limitation. The index i of the codebook element l is included as indication 330. The determination of the index i l (as indication 330) is one of the aspects in the exemplary embodiments herein.

[0124] Figure 4 Shows a graphical example of a sliding window mechanism using FD codebook indices (0 to 21) in the frequency domain and a corresponding mapping with a window of size L = 2M = 14 and an initial point at M 初始 = - 6. More particularly, Figure 4 is an illustration of the sliding window mechanism applied to the FD - based indication and the remapping of the values within the window, with the following example values: N3 = 22; M = 7; and M 初始 = - 6. It should be noted that since the window wraps around, when M 初始 is negative, this means the window slides to the left by - M 初始 , and the window consists of two parts (parts 405 and 410 or 415 and 420), positioned at the two edges of an interval of length N3 as shown in Figure 4 . Also, as described above, for an alphabet of size 2M - 1 (the zero value is always in the window but may not need to be reported), the values in the set change with the parameter M 初始 , and some selected values may be outside the range {1, 2,..., 2M - 1}. In Figure 4 , where M 初始 < 0, there are multiple values outside this range, associated with parts 405 and 408 of layer 1, or parts 415 and 418 of layer 2. In contrast, when M 初始 = 0, the window corresponds to the dashed line in Figure 4 , and no selected elements can be outside the range {1, 2,..., 2M - 1}.

[0125] Figure 4 The configuration in init has υ = 2 layers. The window parameter M 初始 indicated by the index i is the general layer, while the FD - based subset of size M is the specific layer. For layer 1, the FD components selected within the window are shown The mapping from Equation (6), (7), or (8) has the effect of shifting FD components that fall on the right edge of the FD codebook set to the left within the blank portion of the set {0, 1, ..., 2M - 1}. It should be noted that the shift is described as to the left, although a shift to the right is also correct since all shift operations in this document are cyclic. The shift performed by the mapping in Equation (6), (7), or (8) is indicated by reference numeral 430, which shifts the selected FD components within the right portion of window 410 or 420 to portions 408 or 418, respectively. It should be noted that the sizes of portions 410 and 420 in terms of the number of codebook indices are -M 初始 , as indicated by 440-1, and it is the same size as that of portions 408 and 418 indicated by 440-2. Due to the shift performed by the mapping in Equation (6), (7), or (8), the remapped FD components are given by those of layer 1 and those of layer 2 . It should be noted that only the last two elements are shifted for layer 1, and the last four elements are shifted for layer 2, i.e., those elements with indices exceeding 2M - 1 = 13

[0126] As mentioned above, it has been pointed out that the mapping operation allows the set of values IntS that changes with M 初始 to be mapped to a continuous set of 2M values Figure 4 is an illustration of this concept. Regardless of the value of M 初始 , the set of values IntS is mapped to a continuous set of 2M indices (e.g., 0 to 13 in this case) and their corresponding FD components

[0127] The above example can also be used to clarify the following. Before remapping with Equation (8), the (M - 1)-combination of the first layer (without the zeroth element) is After applying the mapping in Equation (8), we get Finally, after applying the mapping in Equation (9), we get Therefore the alphabet of is {0, 1, ..., 2M - 2}, while the alphabet of

[0128] Figure 5 shows a flowchart of the operation involving mapping an FD base subset to the combination indicator f l when applying the sliding window mechanism. In an exemplary embodiment, for example, when N3 > 19, the sliding window can be applied to a large number of PMI subbands. Without these two mappings, it would not be possible to use a codebook with Combination indications in the units place are used to indicate the FD basis subset. Figure 5 It is a logic flow chart for mapping a windowed FD basis to combination indications for PMI reporting and use. The figure shows the operations of one or more exemplary methods according to an exemplary embodiment, the execution results of computer program instructions embodied on a computer-readable memory, the functions executed by logic implemented in hardware, and / or the interconnected devices for performing the functions. The figure is executed by the UE 110, for example, under the control of the control module 140.

[0129] In block 510, the FD basis is set to the following subset:

[0130]

[0131] where for f = 1, 2,... M - 1, In block 520, the UE maps to where See also the above equations (6), (7), or (8). In block 530, the UE 110 maps to where See also the above equation (9). In block 540, the UE 110 determines the combination indication i l . See also the above equation (10). It should be noted that, as described by block 550, blocks 520, 530, and 540 can be considered as mapping the basis subset to the combination indication. In block 560, the UE 110 sends an indication 330 of the combination indication i l (see Figure 3 ), as part of the PMI report 300, which may also be part of a larger CSI report 210 (see Figure 2 ), or as a separate CSI report 210.

[0132] See Figure 6 , which is a flow chart of a method executed by a network node for mapping combination indications for PMI reporting and use to a windowed FD basis. The figure shows the operations of one or more exemplary methods according to an exemplary embodiment, the execution results of computer program instructions embodied on a computer-readable memory, the functions executed by logic implemented in hardware, and / or the interconnected devices for performing the functions. Figure 6 The blocks in are executed by a network (e.g., access) node, such as the RAN node 170, particularly the gNB. Figure 6 The description of assumes the use of a gNB, but this may be just an example of a network node.

[0133] In block 610, the gNB 170 receives a PMI report and the combination indication il CSI report. In block 620, gNB170 performs a de-ranking procedure by following at least one algorithm to find a strictly decreasing sequence from the combined indication i l in In block 630, gNB 170 performs the inverse of the mapping from block 530. Referring to equation (12), for example, it maps from the strictly decreasing sequence to the sequence

[0134] In block 640, gNB 170 performs the inverse of the mapping from block 520. Referring to equation (11), for example, it maps from the sequence f = 1, 2,... M-1 to f = 1, 2,... M-1. Blocks 620, 630, and 640 can be considered as mappings of the combined indication to the FD basis subset. In block 650, gNB 170 uses the FD basis subset and the corresponding FD components to determine the codebook elements to be used for future transmissions.

[0135] Without in any way limiting the scope, interpretation, or application of the claims that follow, one or more of the technical effects of the example embodiments disclosed herein are to address the fact that the values in the set change with the parameter M 初始 and some of the selected values may be outside the range {1, 2,..., 2M-1}. Another technical effect of one or more of the example embodiments disclosed herein is the mapping such that a combined indication of order M-1 and quantity 2M-1 is used instead of using a larger quantity N3-1 of combined indications corresponding to instead of a larger index bitwidth. Related advantages and technical effects include reducing the computational complexity in the ranking and de-ranking algorithms because the size of the lookup tables used in these algorithms is reduced, which results in a simpler search.

[0136] As used in this application, the term "circuitry" may refer to one or more or all of the following:

[0137] (a) Only hardware circuit implementations (such as implementations in only analog and / or digital circuitry), and

[0138] (b) Combinations of hardware circuits and software, such as (if applicable): (i) combinations of analog and / or digital hardware circuits with software / firmware, and (ii) any part of a hardware processor with software (including a digital signal processor), software, and memory, which work together to cause a device (such as a mobile phone or a server) to perform various functions), and

[0139] (c) A hardware circuit and / or a processor, such as a microprocessor or a part of a microprocessor, which requires software (e.g., firmware) to operate, but the software may be absent when not needed for operation.

[0140] This definition of circuitry applies to all uses of the term in this application (including in any claims). As another example, as used in this application, the term "circuitry" also encompasses implementations of only a hardware circuit or a processor (or processors) or implementations of a hardware circuit or a processor and portions of its (or their) accompanying software and / or firmware. The term "circuitry" also encompasses (e.g., and where applicable to a particular claim element) a baseband integrated circuit or a processor integrated circuit of a mobile device or a similar integrated circuit in a server, a cellular network device, or other computing or networking device.

[0141] Embodiments herein may be implemented in software (executed by one or more processors), hardware (e.g., an application specific integrated circuit), or a combination of software and hardware. In an example embodiment, the software (e.g., application logic, instruction set) is maintained on any of a variety of conventional computer-readable media. In the context of this document, a "computer-readable medium" may be any medium or device that can contain, store, communicate, propagate, or transport instructions for use by or in connection with an instruction execution system, apparatus, or device such as a computer, where an example of a computer is described and illustrated in Figure 1 wherein. A computer-readable medium may include a computer-readable storage medium (e.g., memory 125, 155, 171 or other devices), which may be any medium or device that can contain, store, and / or transport instructions for use by or in connection with an instruction execution system, apparatus, or device such as a computer. A computer-readable storage medium does not include a propagated signal.

[0142] If desired, the different functions discussed herein may be performed in a different order and / or simultaneously with each other. Additionally, if desired, one or more of the above functions may be optional or may be combined.

[0143] Although various aspects of the invention are set forth in the independent claims, other aspects of the invention include other combinations of features from the described embodiments and / or dependent claims with the features of the independent claims, rather than only the combinations explicitly set forth in the claims.

[0144] It should also be noted herein that although example embodiments of the invention have been described above, these descriptions should not be taken in a limiting sense. Rather, several variations and modifications can be made without departing from the scope of the invention as defined by the appended claims.

Claims

1. A method for communication, comprising: Determining, by a user equipment (110), a precoding matrix indicator, comprising: Determining an intermediate set of vectors from a frequency-domain codebook, wherein determining the intermediate set of vectors comprises: Based on the initial value M 初始 Select the middle set of the vectors, where M 初始 is selected from the set of non-positive values {-2M + 1, -2M + 2, …, 0}, where there are 2M vectors in the middle set of the vectors, and the index of the middle set of the vectors is defined as IntS = {(M 初始 + i) mod N3, i = 0, 1, …, 2M - 1}, where N3 is the size of the frequency domain codebook of the vectors; Forming a subset of the intermediate set of vectors, wherein there are 2M vectors in the intermediate set of vectors, and wherein forming the subset of the intermediate set of vectors further comprises: Selecting the subset of M vectors from the intermediate set of 2M vectors; Mapping the subset of vectors to a combination indicator, wherein mapping the subset of M vectors to the combination indicator comprises: Apply a first mapping to the non-zero indices of the M vectors within the intermediate set to obtain a first intermediate index defined between 1 and 2M-1 where applying the first mapping includes dividing the non-zero indices of the M vectors within the intermediate set into a first group and a second group, and subtracting a first pre-configured amount from the indices of the second group, according to the following function: where for f = 1, 2, …, M−1, is the non-zero index of the M vectors of layer l, and where the non-zero value is selected from the set of values {1, 2, …, N3−1} associated with the vectors of the frequency domain codebook; Apply a second mapping to the first intermediate index to obtain a second intermediate index defined between 0 and 2M-2 where applying the second mapping includes inverting the sign of the first intermediate index and adding a second preconfigured amount: For a first intermediate index For f = 1, 2, … M-1, a second intermediate index And for layer l; using the second intermediate index in the calculation of the combination coefficient C(x, y) as an independent variable to calculate the combination indicator i l , where using the second intermediate index as an independent variable in the calculation of the combination coefficient to calculate the combination indicator includes: using the second intermediate index as the first independent variable of the combination coefficient to calculate the combination indicator associated with the vector of the non-zero index according to the following function: wherein at least from the combined indication i l and the initial value M 初始 of the indication i init , form the precoding matrix indication such that the precoding matrix indication includes the combined indication i l and the initial value M 初始 of the indication i init ; and Transmitting, by the user equipment (110), the precoding matrix indicator towards a RAN node.

2. The method according to claim 1, wherein the vector having a non - zero index is identified by the indication i 初始 of the initial value M init and the combined indication i l of the initial value M 3. The method according to any one of claims 1 to 2, wherein determining the precoding matrix indicator comprises: Using a reference signal obtained from the RAN node.

4. The method according to any one of claims 1 to 2, wherein the initial value of the intermediate set is common for all reported layers, while the combination indicator is specific for each reported layer.

5. The method according to any one of claims 1 to 2, further comprising: Receiving, by the user equipment and from the RAN node, data to which one or more codebook elements have been applied based on the transmitted precoding matrix indicator.

6. A device for communication, comprising: Components for determining, by a user equipment, a precoding matrix indicator, comprising: Determining an intermediate set of vectors from a frequency-domain codebook, wherein the components for determining the intermediate set of vectors comprise: A component for selecting an intermediate set of the vectors based on an initial value M 初始 where M 初始 is selected from the set of non-positive values {-2M + 1, -2M + 2, …, 0}, and the index of the intermediate set of the vectors is defined as IntS = {(M 初始 + i) mod N3, i = 0, 1, …, 2M - 1}, where N3 is the size of the frequency domain codebook of the vectors; Components for forming a subset of the intermediate set of vectors, wherein there are 2M vectors in the intermediate set of vectors, and wherein the components for forming the subset of the intermediate set of vectors further comprise: Components for selecting the subset of M vectors from the intermediate set of 2M vectors; Mapping the subset of vectors to a combination indicator, wherein the components for mapping the subset of vectors to the combination indicator comprise: Non-zero indices for applying a first mapping to the M vectors within the intermediate set to obtain a first intermediate index defined between 1 and 2M-1 wherein applying the first mapping includes dividing the non-zero indices of the M vectors within the intermediate set according to the initial value of the intermediate set into a first group and a second group, and subtracting a first pre-configured amount from the indices of the second group, according to the following function: where for f = 1, 2, …, M−1, is the non-zero index of the M vectors of layer l, and where the non-zero value is selected from the set of values {1, 2, …, N3−1} associated with the vectors of the frequency-domain codebook; A component for applying a second mapping to the first intermediate index to obtain a second intermediate index defined between 0 and 2M-2 where applying the second mapping includes inverting the sign of the first intermediate index according to the following function and adding a second preconfigured amount: For the first intermediate index For f = 1, 2, … M-1, the second intermediate index And for layer l; For using the second intermediate index in the calculation of the combination coefficient C(x, y) As an independent variable to calculate the combination indicator i l The component, wherein using the second intermediate index as an independent variable in the calculation of the combination coefficient to calculate the combination indicator includes: using the second intermediate index as the first independent variable of the combination coefficient to calculate the combination indicator associated with the vector of the non-zero index According to the following function: wherein for at least indicating the combination i l , and the initial value M 初始 of the indication i init , forming the precoding matrix indication such that the precoding matrix indication includes the combination indication i l , and the initial value M 初始 of the indication i init ; and Components for transmitting the precoding matrix indicator towards a RAN node.

7. The device according to claim 6, wherein Having a non-zero index The vector of which is from the initial value M 初始 The indication i of which init And the combined indication i of which l Is recognized.

8. The apparatus according to any one of claims 6 and 7, wherein determining the precoding matrix indicator comprises: Using a reference signal obtained from the RAN node.

9. The device according to any one of claims 6 and 7, wherein the initial value of the intermediate set is common for all reported layers, while the combination indicator is specific for each reported layer.

10. The apparatus according to any one of claims 6 and 7, further comprising: Components for receiving, by the user equipment and from the RAN node, data to which one or more codebook elements have been applied based on the transmitted precoding matrix indicator.

11. A device for communication, comprising: A component for receiving, at a base station, a precoding matrix indication from a user equipment, the precoding matrix indication including a combined indication i mapping to a subset of M vectors from a frequency-domain codebook l , where the size of the frequency-domain codebook is N3; And Components for determining, using at least the received precoding matrix indicator, information from at least the frequency-domain codebook to be applied to data for transmission towards the user equipment, wherein the components for determining comprise: A component for obtaining a first intermediate index and a second intermediate index, wherein for f = 1, 2, … M-1 and for layer l, the second intermediate index is obtained by performing a de-ranking procedure on the combined indication i according to the following function l : wherein and wherein for f = 1, 2, … M-1 and for layer l, said first intermediate index is obtained by reversing the following function from its corresponding second intermediate index as follows: and For f = 1, 2, … M-1 and for layer l, the component that obtains the non-zero indices of the vector by reversing the following function from its corresponding first intermediate index :​ Among them associated with the vector of the frequency-domain codebook, wherein the precoding matrix indication includes an initial value M 初始 indication i of init , and wherein M 初始 is obtained from the indication i of the initial value M 初始 of init and is obtained thereby.

12. The apparatus according to claim 11, wherein the component for determination comprises: For f = 1, 2, … M-1 and for layer l, obtaining precoding weights from at least the vectors of the frequency-domain codebook corresponding to non-zero indices for application to the data for transmission towards the user equipment.

13. The device according to any one of claims 11 and 12, wherein the device further comprises components for: transmitting, by the base station towards the user equipment, the data to which the information from at least the frequency-domain codebook has been applied.

14. A computer program product, comprising a computer-readable storage medium carrying computer program code for use with a computer, the computer program code comprising: Code for determining a precoding matrix indicator by a user equipment, comprising: Determining an intermediate set of vectors from a frequency-domain codebook, wherein determining the intermediate set of vectors comprises: Based on the initial value M 初始 Select the middle set of the vectors, where M 初始 is selected from the set of non-positive values {-2M + 1, -2M + 2, …, 0}, where there are 2M vectors in the middle set of the vectors, and the index of the middle set of the vectors is defined as IntS = {(M 初始 + i) mod N3, i = 0, 1, …, 2M - 1}, where N3 is the size of the frequency domain codebook of the vectors; Forming a subset of the intermediate set of vectors, wherein there are 2M vectors in the intermediate set of vectors, and wherein forming the subset of the intermediate set of vectors further comprises: Selecting the subset of M vectors from the intermediate set of 2M vectors; Mapping the subset of vectors to a combination indicator, wherein mapping the subset of M vectors to the combination indicator comprises: Apply a first mapping to the non-zero indices of the M vectors within the intermediate set to obtain first intermediate indices defined between 1 and 2M - 1 where applying the first mapping includes dividing the non-zero indices of the M vectors within the intermediate set into a first group and a second group according to the initial value of the intermediate set, and subtracting a first pre-configured amount from the indices of the second group, according to the following function: where for f = 1, 2, …, M - 1, is the non-zero index of the M vectors of layer l, and where the non-zero values are selected from the set of values {1, 2, …, N3 - 1} associated with the vectors of the frequency-domain codebook; Apply a second mapping to the first intermediate index to obtain a second intermediate index defined between 0 and 2M-2 where applying the second mapping includes inverting the sign of the first intermediate index and adding a second preconfigured amount: For the first intermediate index For f = 1, 2, … M-1, the second intermediate index And for layer l; Use the second intermediate index in the calculation of the combination coefficient C(x, y) as an independent variable to calculate the combination indication i l , wherein using the second intermediate index as an independent variable in the calculation of the combination coefficient to calculate the combination indication includes: using the second intermediate index as the first independent variable of the combination coefficient to calculate the combination indication associated with the vector of the non-zero index according to the following function: wherein at least from the combined indication i l and the initial value M 初始 of the indication i init to form the precoding matrix indication such that the precoding matrix indication includes the combined indication i l and the initial value M 初始 of the indication i init ; and Sending the precoding matrix indicator towards a RAN node.

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