Type ii port selection codebook generation

Abstract

Apparatuses, methods, and systems for type-II port selection codebook generation are disclosed. One apparatus (600) includes a processor (605) and a transceiver (625) that receives (805) a set of reference signals. The processor (605) identifies (810) a set of ports based on the set of reference signals. The processor (605) selects (815) a subset of ports from the identified set of ports and generates (820) an amplitude coefficient indicator and at least one phase coefficient indicator for each selected port based on the set of reference signals. The processor (605) generates (825) a CSI report, where the CSI report consists of a type-II port selection codebook corresponding to the generated coefficients and the selected ports.

Description

[0001] This application claims priority to U.S. Provisional Patent Application No. 62 / 986,601, entitled “EXPLOITING CHANNEL CORRELATION FOR TYPE-II CODEBOOK” and filed on March 6, 2020, by Ahmed Hindy, Udar Mittal, and Tyler Brown, which is incorporated herein by reference. TECHNICAL FIELD

[0002] The subject matter disclosed herein relates generally to wireless communications, and more particularly to configurations for exploiting channel correlation to further enhance Type-II codebooks. BACKGROUND

[0003] For Type-II codebooks of Third Generation Partnership Project (“3GPP”) New Radio (“NR”) Release 16, the number of precoder matrix indicator (“PMI”) bits fed back from a user equipment (“UE”) via uplink control information (“UCI”) in a Fifth Generation (“5G”) Node B (“gNB”) can be very large (i.e., greater than 1000 bits at large bandwidth). Moreover, the number of channel state information reference signal (“CSI-RS”) ports transmitted in a downlink (“DL”) channel to enable channel estimation at the UE can also be large, resulting in higher system complexity and loss of resources over reference signaling. SUMMARY

[0004] A procedure for exploiting channel correlation to enhance Type-II port selection codebook generation of channel state information (“CSI”) feedback mechanisms is disclosed. The procedure can be implemented by an apparatus, a system, a method, or a computer program product.

[0005] A method of a UE includes receiving a set of reference signals and identifying a set of ports based on the set of reference signals. The method includes selecting a subset of ports from the identified set of ports and generating an amplitude coefficient indicator and at least one phase coefficient indicator for each selected port based on the reference signals. The method includes generating a CSI report, where the CSI report includes a Type-II port selection codebook corresponding to the generated coefficients and the selected ports.

[0006] A method of a radio access network ("RAN") includes receiving a set of uplink ("UL") reference signals and identifying a set of channel characteristics based on the UL reference signals. Here, the set of channel characteristics includes one or more parameters of angle of arrival and relative delay values corresponding to a set of different channel paths. The method includes generating a set of DL reference signals based on the channel characteristics inferred from the received set of UL reference signals. BRIEF DESCRIPTION OF DRAWINGS

[0007] A more particular description of the embodiments briefly described above will be rendered by reference to specific embodiments that are illustrated in the appended drawings. Understanding that these drawings depict only some embodiments and are not therefore to be considered to be limiting of the scope, embodiments will be described and explained with additional specificity and detail through the use of the accompanying drawings in which:

[0008] Figure 1 is a schematic block diagram illustrating one embodiment of a wireless communication system for CSI feedback reporting;

[0009] Figure 2 is a diagram illustrating one embodiment of CSI reporting, for example, using a Type-II port selection codebook;

[0010] Figure 3 is a diagram illustrating one embodiment of equations used to describe an uplink channel;

[0011] Figure 4 is a diagram illustrating one embodiment of equations used to describe noise estimation of a CSI-RS channel;

[0012] Figure 5 is a diagram illustrating one embodiment of another equation describing noise estimation of a CSI-RS channel;

[0013] Figure 6 is a diagram illustrating one embodiment of a user equipment device that can be used for Type-II port selection codebook generation;

[0014] Figure 7 is a diagram illustrating one embodiment of a network device that can be used for Type-II port selection codebook generation;

[0015] Figure 8 is a flow diagram illustrating one embodiment of a first method Type-II port selection codebook generation; and

[0016] Figure 9 is a flow diagram illustrating one embodiment of a second method Type-II port selection codebook generation. DETAILED DESCRIPTION

[0017] As those skilled in the art will appreciate, the various aspects of the embodiments can be embodied as a system, apparatus, method, or program product. Accordingly, the embodiments can take the form of an entirely hardware embodiment, an entirely software embodiment (including firmware, resident software, micro-code, etc.) or an embodiment combining software and hardware aspects.

[0018] For example, the disclosed embodiments can be implemented as hardware circuitry, including custom very-large-scale integration ("VLSI") circuits or gate arrays, off-the-shelf semiconductors such as logic chips, transistors, or other discrete components. The disclosed embodiments can also be implemented in programmable hardware devices such as field programmable gate arrays, programmable array logic, programmable logic devices or the like. As another example, the disclosed embodiments can include one or more physical or logical blocks of executable code, which may, for example, be organized as an object, procedure, or function.

[0019] Furthermore, embodiments can take the form of a program product embodied in one or more computer readable storage devices storing machine-readable code, computer-readable code, and / or program code, hereinafter also referred to as code. The storage devices can be tangible, non-transitory, and / or non-transmission. The storage devices can not embody signals. In a certain embodiment, the storage devices only take the form of a signal for access to the code.

[0020] Any combination of one or more computer readable medium can be utilized. The computer readable medium can be a computer readable storage medium. The computer readable storage medium can be a storage device storing the code. The storage device can be, for example, but not limited to, an electronic, magnetic, optical, electromagnetic, infrared, holographic, micromechanical, or semiconductor system, apparatus, or device, or any suitable combination of the foregoing.

[0021] More specific examples (a non-exhaustive list) of the storage device would include the following: an electrical connection having one or more wires, a portable computer diskette, a hard disk, a random access memory ("RAM"), a read-only memory ("ROM"), an erasable programmable read-only memory ("EPROM" or Flash memory), a portable compact disc read-only memory ("CD-ROM"), an optical storage device, a magnetic storage device, or any suitable combination of the foregoing. In the context of this document, a computer readable storage medium can be any tangible medium that can contain, or store a program for use by or in connection with an instruction execution system, apparatus, or device.

[0022] Code for carrying out operations for embodiments can be any number of lines and can be written in any combination of one or more programming languages including an object- oriented programming language such as Python, Ruby, Java, Smalltalk, C++, or the like, and conventional procedural programming languages, such as the "C" programming language, and / or machine languages such as assembly languages. The code can execute entirely on the user's computer, partly on the user's computer, as a stand-alone software package, partly on the user's computer and partly on a remote computer or entirely on the remote computer or server. In the latter scenario, the remote computer can be connected to the user's computer through any type of network, including a local area network ("LAN"), wireless LAN ("WLAN"), or a wide area network ("WAN"), or the connection can be made to an external computer (for example, through the Internet using an Internet Service Provider ("ISP")). The embodiments can also be implemented in conjunction with a software module that is contained in another physical entity, such as a server, a personal computer, a laptop computer, a wireless communication device, a mobile telephone, a special-purpose computer, or other device.

[0023] Furthermore, the described features, structures, or characteristics of the embodiments can be combined in any suitable manner in one or more embodiments. In the following description, numerous specific details are provided, such as examples of programming, software modules, user selections, network transactions, database queries, database structures, hardware modules, hardware circuits, hardware chips, etc., to provide a thorough understanding of the embodiments. One skilled in the relevant art will recognize, however, that the embodiments can be practiced without one or more of the specific details, or with other methods, components, materials, and so forth. In other instances, well-known structures, materials, or operations are not shown or described in detail in order to avoid obscuring aspects of the embodiments.

[0024] Reference throughout this specification to "one embodiment", "an embodiment", or similar language means that a particular feature, structure, or characteristic described in connection with the embodiment is included in at least one embodiment. Thus, appearances of the phrases "in one embodiment", "in an embodiment", and similar language throughout this specification may, but do not necessarily, all refer to the same embodiment, but mean "one or more but not all embodiments". Unless otherwise noted, the terms "including", "comprising", "having" and variations thereof herein are intended to be broad and encompass the terms "consisting of" and "consisting essentially of". Unless otherwise noted, the use of the term "or" herein is intended to be inclusive of the meaning of "and / or", unless the context clearly indicates otherwise. Unless otherwise noted, the terms "a" (or "an"), and "the" (and "and / or" or "at least one of") are intended to be broad and encompass the term "one or more", unless the context clearly indicates otherwise.

[0025] As used herein, a list with a conjunction of “and / or” includes any single item in the list or a combination of items in the list. For example, a list of A, B and / or C includes only A, only B, only C, a combination of A and B, a combination of B and C, a combination of A and C, or a combination of A, B, and C. As used herein, a list using the terminology “one or more of’ includes any single item in the list or a combination of items in the list. For example, one or more of A, B, and C includes only A, only B, only C, a combination of A and B, a combination of B and C, a combination of A and C, or a combination of A, B, and C. As used herein, a list using the terminology “one of’ includes one and only one of any single item in the list. For example, “one of A, B, and C” includes only A, only B, or only C and excludes combinations of A, B, and C. As used herein, “a member selected from the group consisting of A, B, and C” includes one and only one of A, B, or C, and excludes combinations of A, B, and C.” As used herein, “a member selected from the group consisting of A, B, and C and combinations thereof’ includes only A, only B, only C, a combination of A and B, a combination of B and C, a combination of A and C, or a combination of A, B, and C.

[0026] The code can also be stored in a storage device that can direct a computer, other programmable data processing apparatus, or other devices to function in a particular manner, such that the instructions stored in the storage device produce an article of manufacture including instructions which implement the function / act specified in the flowchart and / or block diagram block or blocks.

[0027] The code can also be loaded onto a computer, other programmable data processing apparatus, or other devices to cause a series of operational steps to be performed on the computer, other programmable apparatus or other devices to produce a computer implemented process such that the code which execute on the computer or other programmable apparatus provide processes for implementing the functions / acts specified in the flowchart and / or block diagram block or blocks.

[0028] The code can also be loaded onto a computer, other programmable data processing apparatus, or other devices to cause a series of operational steps to be performed on the computer, other programmable apparatus or other devices to produce a computer implemented process such that the code which execute on the computer or other programmable apparatus provide processes for implementing the functions / acts specified in the flowchart and / or block diagram block or blocks.

[0029] The diagrams in the drawings are intended to facilitate understanding of the way in which the various embodiments can be implemented and operate. In this regard, the actual deployment and implementation can differ from that shown and described. The diagrams are intended only to facilitate an understanding of the way in which the various embodiments can be implemented and operated. The diagrams are not intended to limit the scope or context of the various embodiments in any way.

[0030] It should also be noted that in some alternative embodiments, the functions noted in the blocks can occur out of the order noted in the figures. For example, two blocks noted in succession can in fact be executed substantially concurrently or the blocks can sometimes be executed in the reverse order, depending upon the functionality involved. Other steps and methods can be contemplated that are equivalent in function, logic, or effect to those shown.

[0031] Although various arrow types and line types can be employed in the flowchart and / or block diagrams, these are understood not to limit the scope of the respective embodiments. Indeed, some arrows or other connectors can be used to indicate only the logical flow of the depicted embodiment. For instance, an arrow can indicate a waiting or monitoring period of unspecified duration between enumerated steps of the depicted embodiment. It will also be noted that each block of the block diagrams and / or flowchart illustrations, and combinations of blocks in the block diagrams and / or flowchart illustrations, can be implemented by special purpose hardware-based systems that perform the specified functions or steps, or combinations of special purpose hardware and code.

[0032] The description of elements in each figure can refer to elements of previous figures. Like numbers refer to like elements in all figures, including alternative embodiments of like elements.

[0033] Generally, the present disclosure describes systems, methods, and apparatuses for type-II port selection codebook generation. According to 3GPP Release 16 (“Rel-16”), the NR Type-II codebook enables high-resolution DL channel estimation in a RAN comprising at least one gNB. As discussed above, for the NR Rel-16 Type-II codebook, the number of PMI bits fed back from the UE in the gNB via UCI can be very large (e.g., greater than 1000 bits at large bandwidth). Additionally, the number of CSI-RS ports transmitted in the downlink channel to enable channel estimation at the user equipment can also be large, resulting in higher system complexity and loss of resources over reference signaling. Thus, there is a need to further reduce the PMI feedback bits and / or reduce the number of CSI-RS ports utilized in order to improve efficiency.

[0034] A special case of the NR Rel-16 Type-II codebook (referred to as the port selection codebook) is proposed, where the number of CSI-RS ports is reduced via the application of a bottom-layer spatial beamforming procedure. No insight is provided on how to design this beamforming procedure. In addition, it has recently been discussed in the literature that the channel correlation between uplink and downlink channels can be exploited to reduce the CSI feedback overhead even in frequency-division duplex (“FDD”) modes where the UL-DL carrier frequency separation is not too large.

[0035] It is assumed that the gNB is equipped with a two-dimensional (“2D”) antenna array that places N1, N2antenna ports per polarization level and per polarization orientation and that the communication takes place over N3PMI subbands. A PMI subband consists of a set of resource blocks, each of which consists of a set of subcarriers. In this case, 2N1N2N3CSI-RS ports are utilized to achieve a high-resolution DL channel estimation for the NR Rel-16 Type-II codebook implementation.

[0036] To reduce the UL feedback overhead, a discrete Fourier transform (“DFT”) based CSI compression in the spatial domain is applied to each polarization’s L dimensions, where L < N1N2. Similarly, an additional compression in the frequency domain is applied, where an inverse DFT matrix is used to transform each beam of the frequency domain precoding vector to the delay domain, and a subset of the delay domain coefficients’ magnitude and phase values are selected and fed back to the gNB as part of the CSI report.

[0037] The 2N1N2xN3codebook per layer takes the following form

[0038]

[0039] where W1is a 2N1N2x2Lblock-diagonal matrix with two identical diagonal blocks (L < N1N2), i.e.,

[0040]

[0041] and B is an N1N2xLmatrix with columns extracted from a 2D oversampled DFT matrix, as follows.

[0042]

[0043]

[0044]

[0045]

[0046]

[0047] where the superscript T denotes the matrix transpose operation. Note that O1, O2 oversampling factors are assumed for the 2D DFT matrix from which matrix B is extracted. Note that W1 is common across all layers. W f is an N3xM’ matrix (M’ < N3) with columns selected from a strictly oversampled size N3 DFT matrix, as follows

[0048]

[0049]

[0050] Only the indices of the L selected columns of B are reported along with the oversampling indices taking O1O2 values. Similarly, for W F , only the indices of the M’ selected columns of the pre-defined size N3 DFT matrix are reported. Thus, L, M represent the equivalent spatial and frequency dimensions after compression, respectively. Finally, the 2LxM matrix represents the linear combination coefficients (“LCCs”) of the spatial and frequency DFT-based vectors.

[0051] Both are W F and are independent for different layers. The magnitude and phase values of an approximate fraction β of the available 2LM’ coefficients are reported to the gNB as part of the CSI report (β < 1). Thus, for single-layer transmission, a maximum of coefficients are reported per layer (in addition to the indices of the selected L, M’ DFT vectors), resulting in a significant reduction in the CSI report size compared to reporting information for 2N1N2xN3-1 coefficients. Note that coefficients with zero magnitude are indicated via a per-layer bitmap.

[0052] Since all coefficients reported within a layer are normalized with respect to the coefficient with the largest magnitude (strongest coefficient), the relative value of this coefficient is set to unity and no magnitude or phase information is explicitly reported for this coefficient. Only the indication of the index of the strongest coefficient per layer is reported.

[0053] Figure 1 A wireless communication system 100 depicting a CSI feedback report in accordance with embodiments of the present disclosure is depicted. In one embodiment, the wireless communication system 100 includes at least one remote unit 105, a radio access network (“RAN”) 120, and a mobile core network 140. The RAN 120 and the mobile core network 140 form a mobile communication network. The RAN 120 can be comprised of a base unit 121 with which the remote unit 105 communicates using wireless communication links 111. Although Figure 1A particular number of remote units 105, base units 121, wireless communication links 111, RANs 120, and mobile core networks 140 are depicted in FIG. 1, but one of skill in the art will recognize that any number of remote units 105, base units 121, wireless communication links 111, RANs 120, and mobile core networks 140 can be included in the wireless communication system 100.

[0054] In one implementation, the RAN 120 is in compliance with the 5G system specified in the 3GPP specifications. For example, the RAN 120 can be an NG-RAN, implementing NR RAT and / or LTE RAT. In another example, the RAN 120 can include non-3GPP RAT (e.g., Institute of Electrical and Electronics Engineers (“IEEE”) 802.11 compatible WLANs). In another implementation, the RAN 120 is in compliance with the LTE system specified in the 3GPP specifications. More generally, however, the wireless communication system 100 can implement some other open or proprietary communication network, for example, Worldwide Interoperability for Microwave Access (“WiMAX”) or IEEE 802.16 standards, among others. The present disclosure is not intended to be limited to the implementation of any particular wireless communication system architecture or protocol.

[0055] In one embodiment, the remote units 105 can include computing devices, such as desktop computers, laptop computers, personal digital assistants (“PDAs”), tablet computers, smart phones, smart televisions (e.g., televisions connected to the Internet), smart appliances (e.g., appliances connected to the Internet), set-top boxes, game consoles, security systems (including security cameras), vehicle on-board computers, network equipment (e.g., routers, switches, modems), and the like. In some embodiments, the remote units 105 include wearable devices, such as smart watches, fitness bands, optical head-mounted displays, and the like. Moreover, the remote units 105 can be referred to as UEs, subscriber units, mobiles, mobile stations, users, terminals, mobile terminals, fixed terminals, subscriber stations, user terminals, wireless transmit / receive units (“WTRUs”), a device, or by other terminology used in the art. In various embodiments, the remote units 105 include a subscriber identity and / or identification module (“SIM”) and a mobile equipment (“ME”), which provides mobile termination functionality (e.g., radio transmission, handover, speech encoding and decoding, error detection and correction, signaling and access to the SIM). In certain embodiments, the remote units 105 can include a terminal equipment (“TE”) and / or be embedded in an appliance or device (e.g., a computing device, as described above).

[0056] ​The remote units 105 can directly communicate with one or more of the base units 121 in the RAN 120 via uplink ("UL") and downlink ("DL") communication signals. The UL and DL communication signals can be carried over the wireless communication links 111. Here, the RAN 120 is an intermediate network that provides the remote units 105 with access to the mobile core network 140.

[0057] As depicted, the base unit 121 can transmit a set of reference signals 113 that are received at the remote unit 105. The remote unit 105 uses the set of reference signals 113 to determine channel conditions for the wireless communication link 111 between the remote unit 105 and the base unit 121. Based on the determined channel conditions, the remote unit 105 transmits a CSI report 115 to the base unit 121, where the CSI report 115 includes a Type-II port selection codebook, as described in detail below.

[0058] In some embodiments, the remote units 105 communicate with the application servers 151 via a network connection with the mobile core network 140. For example, an application 107 (e.g., a web browser, a media client, a telephone, and / or a Voice-over-Internet Protocol ("VoIP") application) in the remote unit 105 can trigger the remote unit 105 to establish a protocol data unit ("PDU") session (or other data connection) with the mobile core network 140 via the RAN 120. The mobile core network 140 then relays traffic between the remote unit 105 and the application servers 151 using the PDU session. The PDU session represents a logical connection between the remote unit 105 and a user plane function ("UPF") 141.

[0059] To establish a PDU session (or PDN connection), the remote unit 105 must register with the mobile core network 140 (also referred to as "attaching to the mobile core network" in the context of fourth generation ("4G") systems). Note that the remote unit 105 can establish one or more PDU sessions (or other data connections) with the mobile core network 140. Thus, the remote unit 105 can have at least one PDU session for communicating with the packet data network 150. The remote unit 105 can establish additional PDU sessions for communicating with other data networks and / or other communication peers.

[0060] In the context of a 5G system (“5GS”), the term “PDU Session” refers to a data connection providing an end-to-end (“E2E”) user plane (“UP”) connection between a remote unit 105 and a specific Data Network (“DN”) through a UPF 141. The PDU Session supports one or more Quality of Service (“QoS”) Flows. In certain embodiments, there can be a one-to-one mapping between a QoS Flow and a QoS profile, such that all packets belonging to a particular QoS Flow have the same 5G QoS Identifier (“5QI”).

[0061] In the context of a 4G / LTE system, such as an Evolved Packet System (“EPS”), a Packet Data Network (“PDN”) connection (also referred to as an EPS session) provides an E2E UP connection between a remote unit 105 and a PDN. The PDN connection procedure establishes an EPS Bearer, i.e., a tunnel between a remote unit 105 and a Packet Gateway (“PGW”, not shown) in a mobile core network 140. In certain embodiments, there is a one-to-one mapping between an EPS Bearer and a QoS profile, such that all packets belonging to a particular EPS Bearer have the same QoS Class Identifier (“QCI”).

[0062] The base units 121 can be distributed over a geographic region. In certain embodiments, the base units 121 can also be referred to as access terminals, access points, bases, base stations, NodeBs, “NBs,” Evolved NodeBs (abbreviated as eNodeBs or “eNBs,” also referred to as Evolved Universal Terrestrial Access Network (“E-UTRAN”) Node Bs), 5G / NR NodeBs (“gNBs”), Home NodeBs, relay nodes, RAN nodes, or by any other terminology used in the art. The base units 121 are generally part of a RAN, such as RAN 120, which can include one or more controllers that are communicably coupled to one or more corresponding base units 121. These and other elements of radio access networks are not illustrated but are known to those of ordinary skill in the art. The base units 121 connect to the mobile core network 140 via the RAN 120.

[0063] The base units 121 can serve a number of remote units 105 within a serving area, for example, a cell or a cell sector via a wireless communication link 111. The base units 121 can communicate directly with one or more remote units 105 via communication signals. Generally, the base units 121 transmit DL communication signals to serve the remote units 105 in the time, frequency, and / or spatial domain. Additionally, the DL communication signals can be carried over the wireless communication links 111. The wireless communication links 111 can be any suitable carrier in a licensed or unlicensed radio frequency spectrum. The wireless communication links 111 facilitate communication between one or more remote units 105 and / or one or more base units 121. Note that during NR-U operation, the base units 121 and remote units 105 communicate over unlicensed radio frequency spectrum.

[0064] In one embodiment, the mobile core network 140 is a 5GC or an evolved packet core (“EPC”), which can be coupled to a packet data network 150, like the Internet and private data networks, as well as other data networks. A remote unit 105 can have a subscription or other account with the mobile core network 140. Each mobile core network 140 belongs to a single PLMN. The present disclosure is not intended to be limited to the implementation of any particular wireless communication system architecture or protocol.

[0065] The mobile core network 140 includes several network functions (“NFs”). As depicted, the mobile core network 140 includes at least a UPF 141. The mobile core network 140 also includes a number of control plane functions (“CPs”), including but not limited to an access and mobility management function (“AMF”) 143, a session management function (“SMF”) 145, a policy control function (“PCF”) 147, a unified data management function (“UDM”), and a user data repository (“UDR”), which serve the RAN 120.

[0066] The UPF 141 is responsible for packet routing and forwarding, packet inspection, QoS handling, and external PDU session for interconnecting with a data network (DN) in the 5G architecture. The AMF 143 is responsible for termination of NAS signaling, NAS ciphering and integrity protection, registration management, connection management, mobility management, access authentication and authorization, security context management. The SMF 145 is responsible for session management (i.e., session establishment, modification, release), remote unit (i.e., UE) IP address allocation and management, DL data notification, and traffic steering configuration of UPF for proper traffic routing.

[0067] The PCF 147 is responsible for unifying the policy framework, providing policy rules to CP functions, and accessing subscription information for policy decisions in the UDR. The UDM is responsible for generating authentication and key agreement ("AKA") credentials, user identification handling, access authorization, subscription management. The UDR is a repository of subscriber information and can be used to serve many network functions. For example, the UDR can store subscription data, policy-related data, subscriber-related data that is permitted to be exposed to third party applications, etc. In some embodiments, the UDM is quasi co-located with the UDR, described as the combined entity "UDM / UDR" 149.

[0068] In various embodiments, the mobile core network 140 can also include an authentication server function ("AUSF") (which functions as an authentication server), a network repository function ("NRF") (which provides NF service registration and discovery, enabling NFs to identify appropriate services to each other and communicate with each other over application programming interfaces ("APIs")), a network exposure function ("NEF") (which is responsible for enabling customers and network partners to easily access network data and resources), or other NFs defined for the 5GC. In certain embodiments, the mobile core network 140 can include an authentication, authorization, and accounting ("AAA") server.

[0069] Although specific numbers and types of network functions are depicted in Figure 1 the figures, one of skill in the art will recognize that any number and type of network functions can be included in the mobile core network 140. Moreover, in LTE variants in which the mobile core network 140 includes an EPC, the depicted network functions can be replaced with appropriate EPC entities, such as a mobile management entity ("MME"), a serving gateway ("SGW"), a PGW, a home subscriber server ("HSS"), etc. For example, the AMF 143 can be mapped to a MME, the SMF 145 can be mapped to a control plane portion of a PGW and / or to a MME, the UPF 141 can be mapped to a SGW and a user plane portion of a PGW, the UDM / UDR 149 can be mapped to a HSS, etc.

[0070] In various embodiments, the mobile core network 140 supports different types of mobile data connections and different types of network slices, where each mobile data connection utilizes a particular network slice. Here, a "network slice" refers to a portion of the mobile core network 140 that is optimized for a certain traffic type or communication service. A network instance can be identified by a single-network slice selection assistance information ("S-NSSAI"), while a set of network slices for which the remote units 105 are authorized to use is identified by network slice selection assistance information ("NSSAI").

[0071] Here, “NSSAI” refers to a vector value that includes one or more S-NSSAI values. In certain embodiments, various network slices can include separate instances of network functions, such as the SMF 145 and UPF 141. In some embodiments, different network slices can share some common network functions, such as the AMF 143. To facilitate illustration, different network slices are not shown in Figure 1

[0072] While Figure 1 While components of a 5G RAN and 5G core network are depicted, the described embodiments for Type II selection codebook selection apply to other types of communication networks and RATs, including IEEE 802.11 variants, Global System for Mobile Communications (“GSM”, i.e., a 2G digital cellular network), General Packet Radio Service (“GPRS”), Universal Mobile

[0073] In the following description, the term “RAN node” is used for a base station, but it can be replaced by any other radio access node, e.g., gNB, eNB, base station (“BS”), access point (“AP”), etc. Moreover, the operations are mainly described in the context of 5G NR. However, the proposed solutions / methods are equally applicable to other mobile communication systems that support CSI feedback reporting.

[0074] Figure 2 A procedure 200 for CSI reporting, e.g., using a Type II port selection codebook, in accordance with embodiments of the disclosure is depicted. The procedure 200 involves a UE 205 in communication with a RAN node 210. The UE 205 and the RAN node 210 communicate wirelessly via a communication channel 215. Radio signals propagate from transmitter to receiver via the channel 215 and are affected by the combined effects of channel conditions, e.g., scattering, fading, and power decay with distance.

[0075] At step 1, the UE 205 transmits a set of uplink (“UL”) reference signals to the RAN node 210. In one embodiment, the set of UL reference signals includes a demodulation reference signal (“DM-RS”). Here, the DM-RS can be associated with transmission of uplink data on PUSCH or transmission of control signaling on PUCCH. In another embodiment, the set of UL reference signals can include a sounding reference signal (“SRS”).​

[0076] At step 2, the RAN node 210 - having received the set of UL reference signals - identifies a set of channel properties based on the UL reference signals. For example, the channel properties can include parameters corresponding to angle-of-arrival and / or relative delay values of a set of different channel paths. Here, the channel properties describe current conditions of the channel 215.

[0077] At step 3, the RAN node 210 generates a set of DL reference signals based on the determined channel properties. In certain embodiments, the set of DL reference signals can be beamformed using a beamforming function, where the beamforming function is based on the determined channel properties.

[0078] At step 4, the RAN node 210 transmits the generated set of DL reference signals. In various embodiments, the set of DL reference signals includes a set of CSI-RS signals.

[0079] At step 5, the UE 205 identifies a set of ports based on the set of DL reference signals and selects a subset of the identified ports, as described in greater detail below.

[0080] At step 6, for each selected port, the UE 205 generates an amplitude coefficient indicator and at least one phase coefficient indicator.

[0081] At step 7, the UE 205 transmits a CSI report containing a Type-II port selection codebook corresponding to the generated coefficients. This CSI report allows the RAN node 210 to adapt its transmissions to the current conditions / properties of the channel 215. The process of generating the CSI report and Type-II port selection codebook is described in greater detail below.

[0082] For the Type-II port selection codebook, only K (where K < 2N1N2) beamformed CSI-RS ports are utilized in the DL transmission in order to reduce complexity. The KxN3 codebook matrix per layer takes the following form

[0083]

[0084] Here, and W3 follow the same structure as the regular NR Rel-16 Type-II codebook and are layer-specific. W1 is a Kx2L block-diagonal matrix with two identical diagonal blocks, i.e.,

[0085]

[0086] and E is a matrix whose columns are standard unit vectors, as follows.

[0087]

[0088] where is a standard unit vector with 1 at the i-th position. Here, d PS is a radio resource control ("RRC") parameter that takes values {1, 2, 3, 4} under the condition d PS PS takes values and is reported as part of the UL CSI feedback overhead. W1 is common across all layers. Note that m PS parameterizes the position of the first 1 in the first column of E, however d PS represents a row shift corresponding to different values of m PS .

[0089] For K = 16, L = 4 and d PS = 1, the 8 possible realizations of E corresponding to m PS = {0, 1,..., 7} are as follows:

[0090]

[0091]

[0092] For d PS = 2, the 4 possible realizations of E corresponding to m PS = {0, 1, 2, 3} are as follows:

[0093]

[0094] For d PS = 3, the 3 possible realizations of E corresponding to m PS = {0, 1, 2} are as follows

[0095]

[0096] For d PS = 4, the 2 possible realizations of E corresponding to m PS = {0, 1} are as follows

[0097]

[0098] ​To improve the efficiency of Type-II port selection codebook operation, disclosed herein are novel methods that can be implemented individually or jointly to improve the performance of Type-II port selection codebook by exploiting reciprocity between UL and DL channels. The proposed methods vary in reducing CSI-RS transmission complexity, CSI feedback overhead, or both. Different methods are expected to have different impact on performance, which also depends on the validity of the channel reciprocity assumption. Exploiting partial reciprocity between UL and DL channels in NR 5G FDD systems is inspired as a possible improvement of channel feedback reporting in NR.

[0099] Initially, assume a channel with P paths, where P UL , P DL paths, and P UL ≤ P, P DL ≤ P. Here, the number of subbands is N3 with indices n = 0,..., N3-1. The number of antennas per polarization at the RAN node 210 (e.g., gNB) is N1N2 with indices s = 0,..., N1N2-1. The number of antennas per polarization at the UE 205 is N’1N’2 with indices u = 0,..., N’1N’2-1.

[0100] Without loss of generality, one can assume that the coordinate system is rotated such that the RAN node antenna panels occupy the YZ plane. For ease of explanation, assume that the UE antenna panels are parallel to the antenna panels of the RAN node 210. However, the UE antenna panel directions can be general and will be implicit in the channel model.

[0101] Figure 3 Equation 300 is depicted for the UL channel. As Figure 3 shown, the UL channel The following parameters found in Equation 300 are defined:

[0102] Complex gain of path p in the UL channel

[0103] Af: PMI subband spacing

[0104] τ p : Delay of path p

[0105] F c : UL carrier frequency

[0106] c: Speed of light

[0107] (d1, d2): Horizontal and vertical antenna spacing at the gNB. The antennas are placed in the YZ plane

[0108] (d'1, d'2): horizontal and vertical antenna spacing at the UE. The antennas are placed in the YZ plane

[0109] φ p : angle of arrival ("AoA") of the path p (gNB side)

[0110] φ' p : angle of departure ("AoD") of the path p (UE side)

[0111] θ p : zenith AoA ("ZoA") of the path p (gNB side)

[0112] θ' p : zenith AoD ("ZoD") of the path p (UE side)

[0113] t: time index corresponding to a subsequent CSI-RS transmission

[0114] v: relative velocity between the gNB and the UE

[0115] T CSI : duration between CSI-RS transmissions

[0116] υ p : angle between the direction of movement of the path p and the direction of departure of the signal. The direction is in the Z plane

[0117] s: gNB antenna index, such that s = s1.N2 + s2

[0118] u: UE antenna index, such that u = u1.N'2 + u2

[0119] UL channel can be expressed by:

[0120]

[0121] wherein, is the UL channel estimate at the RAN node 210 and is characterized by:

[0122]

[0123] Further:

[0124]

[0125]

[0126]

[0127] wherein

[0128]

[0129]

[0130] Assume the downlink carrier frequency is F c In certain embodiments, the number of delay paths, the path delays, and the angle of arrival / angle of departure pairs are reciprocal for both the UL and DL channels, i.e., the UL and DL channels share similar Only the channel gain g p and, in turn, {a p , ψ p} are not reciprocal.

[0131] The DL channel would then be:

[0132]

[0133] where

[0134]

[0135] Note here that P UL ≠ P DL . Here it is assumed that P UL ≤ P DL .

[0136] Assume the RAN node 210 transmits K / 2 = P UL ≤ N1N2 beamformed CSI-RS ports per polarization to the UE 205, where the 2N1N2 x K CSI-RS beamforming matrix G(n) is designed as one of the following alternatives:

[0137]

[0138] where

[0139]

[0140] Alternatively:

[0141]

[0142] where

[0143]

[0144] Here, diag([λ] k ) is a diagonal matrix whose kth diagonal entry is λ. B is a size matrix whose columns are selected from columns of a size N1N2 DFT matrix, constructed in a similar way as described above with reference to the NR Rel-16 Type-II codebook.

[0145] One of the polarizations of the observed channel, and assuming that the CSI-RS beamforming matrix is set to the first choice, the received signal will have the form

[0146]

[0147] where c k (n) represents the CSI-RS symbol (known at both nodes) and is the background noise.

[0148] Figure 4 Equation 400 is depicted for describing the noise estimate of the CSI-RS channel. The UE 205 can apply some filtering (e.g., zero-forcing (“ZF”) or minimum mean square error (“MMSE”) filtering) to estimate such that the noise estimate of the channel corresponding to CSI-RSkis then characterized by equation 400 as shown by Figure 4

[0149] It is possible to average the received signal across frequency samples to estimate the first term in

[0150]

[0151] In addition, it is possible to define

[0152]

[0153] Note that the smaller the variance of , the better the term is estimated, and thus these 2L out of the 2L amplitude / phase coefficient pairs (across both polarizations) are reported to the RAN node 210, where Recall that 2L < K. Note that if (i) the relative delay in is an integer multiple of 1 / Δf, (ii) P = P UL and (iii) z k,u (n) ~ 0, then will vanish. Typically, this is not always true and the variance of is non-negligible, indicating that some sub-band information needs to be reported by the UE 205.

[0154] In a sequel, it is possible to extend the analysis to the case where and

[0155]

[0156] Figure 5 ​Equation 500, describing noise estimation for a CSI-RS channel according to embodiments of this disclosure, is illustrated here. The expression is as follows Figure 5 Equation 500 is shown. Note that in... The higher the probability that the first term on the right-hand side (“RHS”) of equation 500 will disappear, The greater the mismatch between them.

[0157] Solution 1: CSI-RS Beamforming Matrix Design

[0158] Based on the first solution, the 2N1N2xK CSI-RS beamforming matrix G(n) at frequency band n can be designed as follows:

[0159]

[0160] in

[0161]

[0162] In an alternative embodiment of the first solution, the 2N1N2xK CSI-RS beamforming matrix G(n) at frequency band n can be designed as:

[0163] in

[0164] Where diag([λ]) k B is a diagonal matrix with λ entries on its k-th diagonal. B is the size of a subset of columns that are N1N2 2D DFT matrices. The matrix, the size N1N22D DFT matrix, has a structure similar to that described above with reference to the NR Rel-16 Type II codebook, but completely chosen by the RAN node 210. Other designs of G(n) depend on both the orientation between the UE 205 and the RAN node 210, the zenith emission angle of arrival, and the path delay value.

[0165] Solution 2: CSI Report

[0166] Regarding CSI reporting, the aforementioned method implies the following: each selected port reports an amplitude and phase value (2L coefficients), represented as follows. of in Recall that the UE 205 selects L ports per polarization from K / 2 ports, which may not necessarily be in a specific order, as shown in the following sections. However, several challenges arise:

[0167] Difference in path phase corresponding to different UE antennas The larger, the worse performance in reporting only one phase per port

[0168]

[0169] UL and DL delay values mismatch, i.e.,

[0170] This requires reporting of additional phase values per port to represent the phase difference across different UE antennas, or the phase perturbation across sub-bands, or both. The number of additional phase values reported per port can be parameterized by RRC parameters or specified (and reported) by the UE 205. In this sense, the UE 205 reports one amplitude coefficient indicator per polarization per CSI-RS port + delta phase coefficient indicator per polarization per CSI-RS port, where delta is scaled by any one (or combination) of the following factors:

[0171] Number of SRS ports used for estimating the UL channel

[0172] Rank indicator reported in the CSI report

[0173] Number of PMI sub-bands in the channel

[0174] RRC parameters set by the network

[0175] New parameters reported by the UE 205 to indicate the number of phase coefficients included in the CSI report

[0176] According to the second solution, the UE 205 reports one amplitude coefficient and multiple phase coefficients per CSI-RS port in the CSI report.

[0177] Solution 3: Layer-specific port selection

[0178] Regarding layer-specific port selection, in NR Rel-16, the Type-II port selection codebook for layer v is as follows

[0179]

[0180] where W1(2N1N2xK) is layer-common, however and W f are layer-specific. One way to extend the codebook is via making W1 layer-specific, i.e.,

[0181]

[0182] ​​In this case, the UE 205 selects radically different beam (port) combinations for each layer, e.g., for rank 2 transmission, the UE 205 then reports E1, E2, where the selected ports across the two layers can not intersect, in order to enable separate design of matrices of size Kx2L each

[0183] Here, E1, E2 can each be designed in a similar way as in Rel-16, i.e., per layer each of K / 2 bits, where is the mathematical combination n-Choose-k (a,b). Recall that G(n) is a matrix of size 2N1N2xK, however is a vector of length 2L.

[0184] Another embodiment includes implementing layer-specific As follows

[0185]

[0186] where The change in phase values in

[0187] Another embodiment can also include some slight modification to G(n), as follows

[0188]

[0189] where

[0190]

[0191] and

[0192] As used herein, the mathematical expression “A © B” represents the Hadamard product of matrices A, B, and Ω'(n) is a matrix whose entries have unit magnitude.

[0193] As a third solution, the UE 205 can report a layer-specific port selection matrix in the CSI report, where the port selection per layer can be restricted (only consecutive ports), or via a bitmap of free selection, or via combinatorial free selection.

[0194] Solution 4: CQI reporting

[0195] ​With respect to CQI reporting, given UL and DL channel reciprocity, the RAN node 210 already knows some partial information of the DL channel (path delay, azimuth / zenith angle of departure) except for the non-reciprocal channel gain. Given that the channel gain is frequency-independent, the UE 205 can report only wideband CQI to the RAN node 210, however given the wideband CQI and the partial channel information inferred from the UL channel, the RAN node 210 is able to infer sub-band CQI.

[0196] As a fourth solution, the UE 205 can report only wideband CQI in the CSI report.

[0197] Figure 6 A user equipment apparatus 600 that can be used for Type-II port selection codebook generation in accordance with embodiments of the present disclosure is depicted. In various embodiments, the user equipment apparatus 600 is used to implement one or more of the above-described solutions. The user equipment apparatus 600 can be one embodiment of the above-described remote unit 105, UE 205. Furthermore, the user equipment apparatus 600 can include a processor 605, a memory 610, an input device 615, an output device 620, and a transceiver 625.

[0198] In some embodiments, the input device 615 and the output device 620 are combined into a single device, such as a touch screen. In certain embodiments, the user equipment apparatus 600 can not include any input device 615 and / or output device 620. In various embodiments, the user equipment apparatus 600 can include one or more of the processor 605, the memory 610, and the transceiver 625, and can not include the input device 615 and / or the output device 620.

[0199] As depicted, the transceiver 625 includes at least one transmitter 630 and at least one receiver 635. In some embodiments, the transceiver 625 communicates with one or more cells (or wireless coverage areas) supported by one or more base station units 121. In various embodiments, the transceiver 625 can communicate with the RAN using one or more (e.g., up to four) transmission layers. Additionally, the transceiver 625 can support at least one network interface 640 and / or application interface 645. The application interface 645 can support one or more APIs. The network interface 640 can support 3GPP reference points, such as Uu, N1, PC5, and / or the like. Other network interfaces 640 can be supported, as appreciated by one of ordinary skill in the art.

[0200] In one embodiment, the processor 605 can include any known controller capable of executing computer-readable instructions and / or capable of performing logical operations. For example, the processor 605 can be a microcontroller, a microprocessor, a central processing unit (“CPU”), a graphics processing unit (“GPU”), an auxiliary processing unit, a field programmable gate array (“FPGA”), or similar programmable controller. In some embodiments, the processor 605 executes instructions stored in the memory 610 to perform the methods and routines described herein. The processor 605 is communicably coupled to the memory 610, the input device 615, the output device 620, and the transceiver 625. In certain embodiments, the processor 605 can include an application processor (also known as a “main processor”) that manages application-domain and operating system (“OS”) functions and a baseband processor (also known as a “baseband radio processor”) that manages radio functions.

[0201] In various embodiments, the processor 605 controls the user equipment apparatus 600 to implement the UE behaviors described above. For Type-II port selection codebook generation, the processor 605 receives a set of downlink reference signals via the transceiver 625. In some embodiments, the set of received downlink reference signals are beamformed using a beamforming function. In such embodiments, the beamforming function is based on one or more channel characteristics, including parameters corresponding to at least one of angle of arrival values and relative delay values for a set of different channel paths.

[0202] In one embodiment, the columns of the beamforming function at a given frequency index are based on orthogonal columns extracted from a Fourier-based transform, where each of the columns is scaled by a fundamentally different phase value. In another embodiment, the columns of the beamforming function at a given frequency index are based on parameters corresponding to at least one of angle of arrival values and relative delay values for a subset of the set of different channel paths.

[0203] The processor identifies a set of ports based on the set of downlink reference signals and selects a subset of ports from the identified set of ports. For example, the user equipment apparatus 600 can be configured with 6 to 32 ports. After receiving the set of downlink reference signals, the processor 605 can then select a subset of ports, e.g., 2 to 6 ports, for CSI feedback. In some embodiments, the set of downlink reference signals corresponds to multiple transmission layers, where a different subset of the set of ports is selected for each transmission layer.

[0204] In some embodiments, the port selection for each transmission layer is limited to a set of contiguous ports. In certain embodiments, the port selection for each transmission layer is polarization-common. In one embodiment, a bitmap is used to indicate the port selection for each transmission layer. In another embodiment, a combined value is used to indicate the port selection for each transmission layer.

[0205] The processor 605 generates an amplitude coefficient indicator and at least one phase coefficient indicator for each selected port based on the set of downlink reference signals. In some embodiments, the indicated amplitude coefficient corresponds to multiple phase coefficients for each port. In other embodiments, the indicated amplitude coefficient corresponds to one phase coefficient for each port.

[0206] The processor 605 generates a CSI report and controls the transceiver 625 to transmit the CSI report to the RAN. Here, the CSI report consists of a Type-II port selection codebook corresponding to the generated coefficients and the selected ports. In some embodiments, the CSI report indicates a set of one or more phase coefficient values for each selected port. In some embodiments, the CSI report includes only a wideband CQI value.

[0207] In some embodiments, the CSI report includes a subset of the set of ports selected for a particular layer. In certain embodiments, the port selection for each transmission layer is limited to a set of consecutive ports. In certain embodiments, the port selection for each transmission layer is polarization-universal. In one embodiment, a bitmap is used to indicate the port selection for each transmission layer. In another embodiment, a combined value is used to indicate the port selection for each transmission layer.

[0208] In one embodiment, the memory 610 is a computer readable storage medium. In some embodiments, the memory 610 includes volatile computer storage media. For example, the memory 610 can include a RAM, including dynamic RAM (“DRAM”), synchronous dynamic RAM (“SDRAM”), and / or static RAM (“SRAM”). In some embodiments, the memory 610 includes non-volatile computer storage media. For example, the memory 610 can include a hard disk drive, a flash memory, or any other suitable non-volatile computer storage device. In some embodiments, the memory 610 includes both volatile and non-volatile computer storage media.

[0209] In some embodiments, the memory 610 stores data related to Type-II port selection codebook generation. For example, the memory 610 can store various parameters, configurations, resource assignments, policies, and the like as described above. In certain embodiments, the memory 610 also stores program code and related data, such as an operating system or other controller algorithms operating on the user equipment apparatus 600 and one or more software applications.

[0210] In one embodiment, input device 615 can include any known computer input device, including a touch panel, buttons, a keyboard, a stylus, a microphone, or the like. In some embodiments, input device 615 can be integrated with output device 620, e.g., as a touch screen or similar touch-sensitive display. In some embodiments, input device 615 includes a touch screen such that text can be input using a virtual keyboard displayed on the touch screen and / or by handwriting on the touch screen. In some embodiments, input device 615 includes two or more different devices, such as a keyboard and a touch panel.

[0211] In one embodiment, output device 620 is designed to output visual, audible, and / or tactile signals. In some embodiments, output device 620 includes an electronically controllable display or display device capable of outputting visual data to a user. For example, output device 620 can include, but is not limited to, an LCD display, a LED display, an OLED display, a projector, or similar display device capable of outputting images, text, etc., to a user. As another non-limiting example, output device 620 can include a wearable display separate from, but communicatively coupled to, the rest of user device apparatus 600, such as a smart watch, smart glasses, a heads-up display, or the like. Further, output device 620 can be a component of a smart phone, a personal digital assistant, a television, a table computer, a notebook (laptop) computer, a personal computer, a vehicle dashboard, or the like.

[0212] In certain embodiments, output device 620 includes one or more speakers for producing sound. For example, output device 620 can produce an audible alert or notification (e.g., a beep or chime). In some embodiments, output device 620 includes one or more haptic devices for producing vibrations, motion, or other haptic feedback. In some embodiments, all or portions of output device 620 can be integrated with input device 615. For example, input device 615 and output device 620 can form a touch screen or similar touch-sensitive display. In other embodiments, output device 620 can be located near input device 615.

[0213] Transceiver 625 communicates with one or more network functions of a mobile communication network via one or more access networks. Transceiver 625 operates under the control of processor 605 to transmit and to receive messages, data, and other signals. For example, processor 605 can selectively activate transceiver 625 (or portions thereof) at particular times in order to send and receive messages.

[0214] The transceiver 625 includes at least transmitter 630 and at least one receiver 635. One or more transmitters 630 can be used to provide UL communication signals to a base unit 121, such as the UL transmissions described herein. Similarly, one or more receivers 635 can be used to receive DL communication signals from the base unit 121, as described herein. Although only one transmitter 630 and one receiver 635 are illustrated, the user equipment apparatus 600 can have any suitable number of transmitters 630 and receivers 635. Further, the transmitter 630 and receiver 635 can be any suitable type of transmitters and receivers. In one embodiment, the transceiver 625 includes a first transmitter / receiver pair for communicating with a mobile communication network over licensed radio spectrum and a second transmitter / receiver pair for communicating with a mobile communication network over unlicensed radio spectrum.

[0215] In certain embodiments, the first transmitter / receiver pair for communicating with a mobile communication network over licensed radio spectrum and the second transmitter / receiver pair for communicating with a mobile communication network over unlicensed radio spectrum can be combined into a single transceiver unit, such as a single chip that performs functions for both licensed and unlicensed radio spectrum. In some embodiments, the first transmitter / receiver pair and the second transmitter / receiver pair can share one or more hardware components. For example, certain transceivers 625, transmitters 630, and receivers 635 can be implemented as physically separate components that access shared hardware resources and / or software resources, such as, for example, the network interface 640.

[0216] In various embodiments, one or more transmitters 630 and / or one or more receivers 635 can be implemented and / or integrated into a single hardware component, such as a multi-transceiver chip, a system-on-a-chip, an ASIC, or other type of hardware component. In certain embodiments, one or more transmitters 630 and / or one or more receivers 635 can be implemented and / or integrated into a multi-chip module. In some embodiments, other components, such as the network interface 640, or other hardware components / circuits, can be integrated with any number of transmitters 630 and / or receivers 635 into a single chip. In such embodiments, the transmitters 630 and receivers 635 can be logically configured as a transceiver 625 that uses one common control signal or as modular transmitters 630 and receivers 635 implemented in the same hardware chip or multi-chip module.

[0217] Figure 7A network device apparatus 700 that can generate a type-II port selection codebook is depicted in accordance with embodiments of the present disclosure. In one embodiment, the network device apparatus 700 can be one implementation of a RAN node, such as the base unit 121, the RAN node 210, or a gNB as described above. In another embodiment, the network apparatus 700 can be one implementation of an AMF, such as the AMF 143 and / or the AMF 215 described above. Further, the base station network apparatus 700 can include a processor 705, a memory 710, an input device 715, an output device 720, and a transceiver 725.

[0218] In some embodiments, the input device 715 and the output device 720 are combined into a single device, such as a touch screen. In certain embodiments, the network apparatus 700 can not include any input device 715 and / or output device 720. In various embodiments, the network apparatus 700 can include one or more of the processor 705, the memory 710, and the transceiver 725, and can not include the input device 715 and / or the output device 720.

[0219] As depicted, the transceiver 725 includes at least one transmitter 730 and at least one receiver 735. Here, the transceiver 725 communicates with one or more remote units 105. Additionally, the transceiver 725 can support at least one network interface 740 and / or application interface 745. The application interface 745 can support one or more APIs. The network interface 740 can support 3GPP reference points, such as Uu, Nl, N2, and N3. Other network interfaces 740 can be supported, as appreciated by one of ordinary skill in the art. The transceiver 725 can be used for transmitting and receiving information such as messages, data, and / or instructions, etc., to and from the network apparatus 700.

[0220] In one embodiment, the processor 705 can include any known controller capable of executing computer-readable instructions and / or capable of performing logical operations. For example, the processor 705 can be a microcontroller, a microprocessor, a CPU, a GPU, an auxiliary processor, a FPGA, or similar programmable controller. In some embodiments, the processor 705 executes instructions stored in the memory 710 to perform methods and routines described herein. The processor 705 is communicatively coupled to the memory 710, the input device 715, the output device 720, and the transceiver 725.

[0221] In various embodiments, the network apparatus 700 is a RAN node (e.g., a gNB) that transmits UE configurations and receives measurement reports, as described herein. In such embodiments, the processor 705 controls the network apparatus 700 to perform the behaviors described above. When operating as a RAN node, the processor 705 can include an application processor (also known as “main processor”) that manages application-domain and operating system (“OS”) functions and a baseband processor (also known as “baseband radio processor”) that manages radio functions.

[0222] In various embodiments, the processor 705 controls the network device 700 to implement the above-described RAN behavior. To generate a beamforming matrix for each frequency index of a Type-II port selection codebook, the processor 705 identifies a set of channel characteristics based on the uplink reference signals. Here, the set of channel characteristics includes parameters corresponding to one or more angle of arrival and relative delay values of different channel paths. The processor 705 generates a set of downlink reference signals based on the channel characteristics inferred from the received set of uplink reference signals. The processor 705 controls the transceiver 725 to transmit the generated set of downlink reference signals, e.g., to one or more UEs served by the network device 700.

[0223] In some embodiments, the generated set of downlink reference signals is beamformed using a beamforming function. In such embodiments, the beamforming function is based on one or more channel characteristics. In one embodiment, the columns of the beamforming function at a given frequency index are based on orthogonal columns extracted from a Fourier-based transform, where each column is scaled by a fundamentally different phase value. In another embodiment, the columns of the beamforming function at a given frequency index are based on parameters corresponding to at least one of an angle of arrival value and a relative delay value of a subset of the set of different channel paths.

[0224] In one embodiment, the memory 710 is a computer readable storage medium. In some embodiments, the memory 710 includes volatile computer storage media. For example, the memory 710 can include a RAM, including dynamic RAM (“DRAM”), synchronous dynamic RAM (“SDRAM”), and / or static RAM (“SRAM”). In some embodiments, the memory 710 includes non-volatile computer storage media. For example, the memory 710 can include a hard disk drive, a flash drive, or any other suitable non-volatile computer storage device. In some embodiments, the memory 710 includes both volatile and non-volatile computer storage media.

[0225] In some embodiments, the memory 710 stores data related to Type-II port selection codebook generation. For example, the memory 710 can store parameters, configurations, resource assignments, policies, and the like, as described above. In certain embodiments, the memory 710 also stores program code and related data, such as an operating system or other controller algorithms operating on the network device 700 and one or more software applications.

[0226] In one embodiment, input device 715 can include any known computer input device, including a touch panel, buttons, a keyboard, a stylus, a microphone, or the like. In some embodiments, input device 715 can be integrated with output device 720, e.g., as a touch screen or similar touch-sensitive display. In some embodiments, input device 715 includes a touch screen such that text can be input using a virtual keyboard displayed on the touch screen and / or by handwriting on the touch screen. In some embodiments, input device 715 includes two or more different devices, such as a keyboard and a touch panel.

[0227] In one embodiment, output device 720 is designed to output visual, audible, and / or tactile signals. In some embodiments, output device 720 includes an electronically controllable display or display device capable of outputting visual data to a user. For example, output device 720 can include, but is not limited to, an LCD display, a LED display, an OLED display, a projector, or similar display device capable of outputting images, text, etc., to a user. As another non-limiting example, output device 720 can include a wearable display separate from, but communicatively coupled to, the rest of network device 700, such as a smart watch, smart glasses, a heads-up display, or the like. Further, output device 720 can be a component of a smart phone, a personal digital assistant, a television, a table computer, a notebook (laptop) computer, a personal computer, a vehicle dashboard, or the like.

[0228] In certain embodiments, output device 720 includes one or more speakers for producing sound. For example, output device 720 can produce an audible alert or notification (e.g., a beep or chime). In some embodiments, output device 720 includes one or more haptic devices for producing vibrations, motion, or other haptic feedback. In some embodiments, all or portions of output device 720 can be integrated with input device 715. For example, input device 715 and output device 720 can form a touch screen or similar touch-sensitive display. In other embodiments, output device 720 can be located near input device 715.

[0229] Transceiver 725 includes at least transmitter 730 and at least one receiver 735. One or more transmitters 730 can be used to communicate with UEs, as described herein. Similarly, one or more receivers 735 can be used to communicate with network functions in a PLMN and / or RAN, as described herein. Although only one transmitter 730 and one receiver 735 are illustrated, network device apparatus 700 can have any suitable number of transmitters 730 and receivers 735. Further, transmitter 730 and receiver 735 can be any suitable type of transmitters and receivers.

[0230] Figure 8One embodiment of a method 800 for Type-II port selection codebook generation according to embodiments of the disclosure is depicted. In various embodiments, the method 800 is performed by a UE, such as the remote unit 105, the UE 205, and / or the user equipment apparatus 600, as described above. In some embodiments, the method 800 is performed by a processor, such as a microcontroller, a microprocessor, a CPU, a GPU, an auxiliary processing unit, a FPGA, or the like.

[0231] The method 800 begins and receives 805 a set of reference signals. The method 800 includes identifying 810 a set of ports based on the set of reference signals. The method 800 includes selecting 815 a subset of ports from the identified set of ports. The method 800 includes generating 820 an amplitude coefficient indicator and at least one phase coefficient indicator for each selected port based on the set of reference signals. The method 800 includes generating 825 a CSI report, where the CSI report consists of a Type-II port selection codebook corresponding to the generated coefficients and the selected ports. The method 800 ends.

[0232] Figure 9 One embodiment of a method 900 for Type-II port selection codebook generation according to embodiments of the disclosure is depicted. In various embodiments, the method 900 is performed by a RAN node, such as the base unit 121, gNB 210, and / or network apparatus 700, as described above. In some embodiments, the method 900 is performed by a processor, such as a microcontroller, a microprocessor, a CPU, a GPU, an auxiliary processing unit, a FPGA, or the like.

[0233] The method 900 begins and receives 905 a set of uplink reference signals. The method 900 includes identifying 910 a set of channel properties based on the uplink reference signals, the set of channel properties including parameters corresponding to at least one of an angle of arrival value and a relative delay value for a set of different channel paths. The method 900 includes generating 915 a set of downlink reference signals based on the channel properties inferred from the received set of uplink reference signals. The method 900 ends.

[0234] Disclosed herein is a first apparatus for type-II port selection codebook generation according to embodiments of the disclosure. The first apparatus can be implemented by a UE, such as the remote units 105, UE 205, and / or user equipment apparatus 600 described above. The first apparatus includes a processor and a transceiver that receives a set of reference signals (e.g., downlink reference signals). The processor identifies a set of ports based on the set of reference signals and selects a subset of ports from the identified set of ports. The processor generates an amplitude coefficient indicator and at least one phase coefficient indicator for each selected port based on the set of reference signals. The processor generates a CSI report, where the CSI report consists of a type-II port selection codebook corresponding to the generated coefficients and the selected ports.

[0235] In some embodiments, the CSI report indicates a set of one or more phase coefficient values for each of the selected ports. In some embodiments, the set of reference signals corresponds to a plurality of transmission layers, where a different subset of the set of ports is selected for each transmission layer. In certain embodiments, the CSI report includes a layer-specific selection of the subset of the set of ports.

[0236] In some embodiments, the port selection per layer is limited to a set of contiguous ports. In certain embodiments, the port selection per layer is polarization-common. In one embodiment, the port selection per layer is indicated using a bitmap. In another embodiment, the port selection per layer is indicated using a combined value.

[0237] In some embodiments, the indicated amplitude coefficient per port corresponds to a plurality of phase coefficients. In other embodiments, the indicated amplitude coefficient per port corresponds to one phase coefficient. In some embodiments, the CSI report includes only a wideband CQI value.

[0238] In some embodiments, the received set of reference signals are beamformed using a beamforming function. In such embodiments, the beamforming function is based on one or more channel characteristics including parameters corresponding to at least one of an angle of arrival value and a relative delay value for a set of different channel paths.

[0239] In one embodiment, the columns of the beamforming function at a given frequency index are based on orthogonal columns drawn from a Fourier-based transform, where each of the columns is scaled by a fundamentally different phase value. In another embodiment, the columns of the beamforming function at a given frequency index are based on parameters corresponding to at least one of an angle of arrival value and a relative delay value for a subset of the set of different channel paths.

[0240] Disclosed herein is a first method for type-II port selection codebook generation according to embodiments of the disclosure. The first method can be performed by a UE, such as the remote unit 105, UE 205, and / or user equipment apparatus 600 described above. The first method includes receiving a set of reference signals and identifying a set of ports based on the set of reference signals. The first method includes selecting a subset of ports from the identified set of ports and generating an amplitude coefficient indicator and at least one phase coefficient indicator for each selected port based on the set of reference signals. The first method includes generating a CSI report, where the CSI report consists of a type-II port selection codebook corresponding to the generated coefficients and the selected ports.

[0241] In some embodiments, the CSI report indicates a set of one or more phase coefficient values for each of the selected ports. In some embodiments, the set of reference signals corresponds to a plurality of transmission layers, where a different subset of the set of ports is selected for each transmission layer. In some embodiments, the CSI report includes a layer-specific selection of the subset of the set of ports.

[0242] In certain embodiments, the port selection per layer is limited to a set of contiguous ports. In certain embodiments, the port selection per layer is polarization-common. In one embodiment, the port selection per layer is indicated using a bitmap. In another embodiment, the port selection per layer is indicated using a combined value.

[0243] In some embodiments, the indicated amplitude coefficient per port corresponds to a plurality of phase coefficients. In other embodiments, the indicated amplitude coefficient per port corresponds to one phase coefficient. In some embodiments, the CSI report includes only a wideband CQI value.

[0244] In some embodiments, the received set of reference signals are beamformed using a beamforming function. In such embodiments, the beamforming function is based on one or more channel characteristics including parameters corresponding to at least one of an angle of arrival value and a relative delay value for a set of different channel paths.

[0245] In one embodiment, the columns of the beamforming function at a given frequency index are based on orthogonal columns drawn from a Fourier-based transform, where each of the columns is scaled by a fundamentally different phase value. In another embodiment, the columns of the beamforming function at a given frequency index are based on parameters corresponding to at least one of an angle of arrival value and a relative delay value for a subset of the set of different channel paths.

[0246] Disclosed herein is a second apparatus for generating a beamforming matrix for each frequency index of a Type-II port selection codebook according to embodiments of the disclosure. The second apparatus can be implemented by a RAN node in a communication network such as the base unit 121, gNB 210, and / or network apparatus 700 described above. The second apparatus includes a processor and a transceiver that receives a set of uplink reference signals. The processor identifies a set of channel properties based on the uplink reference signals, the set of channel properties including parameters corresponding to at least one of angle of arrival values and relative delay values of a set of different channel paths. The processor generates a set of downlink reference signals based on the channel properties inferred from the received set of uplink reference signals.

[0247] In some embodiments, the generated set of downlink reference signals is beamformed using a beamforming function. In such embodiments, the beamforming function is based on the set of channel properties. In one embodiment, columns of the beamforming function at a given frequency index are based on orthogonal columns extracted from a Fourier-based transform, where each of the columns is scaled by a fundamentally different phase value. In another embodiment, columns of the beamforming function at a given frequency index are based on parameters corresponding to at least one of angle of arrival values and relative delay values of a subset of the set of different channel paths.

[0248] Disclosed herein is a second method for generating a beamforming matrix for each frequency index of a Type-II port selection codebook according to embodiments of the disclosure. The second method can be performed by a RAN node in a communication network such as the base unit 121, gNB 210, and / or network apparatus 700 described above. The second method includes receiving a set of uplink reference signals and identifying a set of channel properties based on the uplink reference signals, the set of channel properties including parameters corresponding to at least one of angle of arrival values and relative delay values of a set of different channel paths. The second method includes generating a set of downlink reference signals based on the channel properties inferred from the received set of uplink reference signals.

[0249] In some embodiments, the generated set of downlink reference signals is beamformed using a beamforming function. In such embodiments, the beamforming function is based on the set of channel properties. In one embodiment, columns of the beamforming function at a given frequency index are based on orthogonal columns extracted from a Fourier-based transform, where each of the columns is scaled by a fundamentally different phase value. In another embodiment, columns of the beamforming function at a given frequency index are based on parameters corresponding to at least one of angle of arrival values and relative delay values of a subset of the set of different channel paths.

[0250] Embodiments can be practiced in other specific forms. The described embodiments are to be considered in all respects only as illustrative and not restrictive. Accordingly, the scope of the application is indicated by the appended claims rather than by the foregoing description. All changes that come within the meaning of and equivalency of the claims are intended to be embraced within the range of the claims.

Claims

1. A user equipment ("UE") apparatus, comprising: a transceiver; and a processor coupled to the transceiver, the processor configured to cause the apparatus to: receive a set of channel state information ("CSI") reference signals ("CSI-RS"); identify a set of CSI-RS ports based on the set of CSI-RS; select a subset of CSI-RS ports from the set of identified CSI-RS ports based on a free selection of CSI-RS ports from the identified CSI-RS ports; generate at least one amplitude coefficient indicator and at least one phase coefficient indicator for each selected CSI-RS port based on the set of CSI-RS; and generate a CSI report, wherein the CSI report includes a Type-II port selection codebook corresponding to the generated coefficients and the selected ports, wherein the CSI report further includes an indication of the free selection of the CSI-RS ports from the identified pair of CSI-RS ports using a combination value, wherein the combination value is in the form of an n-Choose-k mathematical combination function ("nCk") that selects an integer value of b elements from a set of integer values of a elements. ”).

2. The apparatus of claim 1, wherein, the CSI report indicating a set of one or more phase coefficient values for each of the selected ports.

3. The apparatus of claim 1, wherein, the set of CSI-RS corresponding to a plurality of transmission layers, wherein a different subset of the set of ports is selected for each transmission layer.

4. The apparatus of claim 3, wherein, the CSI report including a layer-specific selection of the subset of the set of ports.

5. The apparatus of claim 4, wherein, the port selection per layer is polarization-common.

6. The apparatus of claim 1, wherein, the processor configured to cause the device to indicate the free selection of the CSI-RS ports from the identified CSI-RS ports using a bitmap.

7. The apparatus of claim 1, wherein, using the combination value to indicate a number of bits required for the free selection of the CSI-RS ports from the identified set of CSI-RS ports is K bits, where K corresponds to a number of the identified set of CSI-RS ports, L corresponds to a number of beams, the function is a base-2 logarithm function, and is a ceiling function that is a smallest integer value greater than or equal to its input argument.

8. The apparatus of claim 1, wherein, each port, each indicated amplitude coefficient corresponding to one phase coefficient.

9. A radio access network ("RAN") apparatus, comprising: a transceiver; and a processor coupled to the transceiver, the processor configured to cause the apparatus to: generate a set of channel state information ("CSI") reference signals ("CSI-RS"); transmit the set of CSI-RS to a user equipment ("UE"); receive a CSI report from the UE, wherein the CSI report includes a Type-II port selection codebook corresponding to the generated coefficients and a free selection of CSI-RS ports corresponding to the CSI-RS, at least one amplitude coefficient indicator for each selected CSI-RS port, and at least one phase coefficient indicator for each selected CSI-RS port, wherein the CSI report further includes an indication of the free selection of the CSI-RS ports from the identified pair of CSI-RS ports using a combination value, wherein the combination value is in the form of an n-Choose-k mathematical combination function ("nCk") that selects an integer value of b elements from a set of integer values of a elements. ”).

10. The apparatus of claim 9, wherein, to transmit the set of CSI-RS, the processor configured to cause the apparatus to beamform the CSI-RS using a beamforming function, wherein the beamforming function is based on one or more channel characteristics including parameters corresponding to a set of relative delay values and one or more angle of arrival values of a plurality of different channel paths.

11. The apparatus of claim 10, wherein, a column of the beamforming function at a given frequency index is based on a quadrature column extracted from a Fourier-based transform, wherein each of the columns is scaled by a fundamentally different phase value.

12. The apparatus of claim 10, wherein, a column of the beamforming function at a given frequency index is based on the parameters corresponding to one or more angle of arrival values and relative delay values of a subset of the set of different channel paths.

13. The apparatus of claim 10, wherein, the one or more channel characteristics are based on a set of uplink reference signals received at the apparatus.

14. A method of a radio access network ("RAN") node for generating a beamforming matrix for each frequency index of a Type-II port selection codebook, the method comprising generating a set of channel state information ("CSI") reference signals ("CSI-RSs"); transmitting the set of CSI-RSs to a user equipment ("UE"); receiving a CSI report from the UE, wherein the CSI report includes a Type-II port selection codebook corresponding to the generated coefficients and a free selection of CSI-RS ports corresponding to the CSI-RSs, at least one amplitude coefficient indicator for each selected CSI-RS port, and at least one phase coefficient indicator for each selected CSI-RS port, wherein, The CSI report further includes an indication of the free selection of the CSI-RS ports from the identified pair of CSI-RS ports using a combination value, where the combination value is in the form of an n-Choose-k mathematical combination function ("nCk") that selects an integer value of b elements from a set of integer values of a elements. ”).

15. The method of claim 14, wherein, transmitting the set of CSI-RSs includes beamforming the CSI-RSs using a beamforming function, wherein the beamforming function is based on one or more channel characteristics including parameters corresponding to one or more of a set of relative delay values and one or more of arrival angles of a plurality of different channel paths.

16. The method of claim 15, wherein, a column of the beamforming function at a given frequency index is based on an orthogonal column extracted from a Fourier-based transform, wherein each of the columns is scaled by a fundamentally different phase value.

17. The method of claim 16, wherein, a column of the beamforming function at a given frequency index is based on the parameters corresponding to one or more of an arrival angle value and a relative delay value of a subset of the set of different channel paths.

18. The method of claim 16, wherein, the one or more channel characteristics are based on a set of uplink reference signals received at the RAN node.

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