Methods, architectures, apparatuses and systems for hybrid vector and scalar quantization for channel state information compression and feedback

Abstract

A wireless transmit / receive unit (WTRU) is described herein. The WTRU may receive one or more reference signals and determine channel state information (CSI) based on the one or more reference signals. The WTRU may determine a latent vector based on a compression of the CSI and perform vector quantization of the vector for a plurality of sets of vector quantization codebooks. The WTRU may select (1) a set of vector quantization codebooks from the plurality of sets of vector quantization codebooks and (2) a number of bits for scalar quantization based on any of a CSI feedback size and a reconstruction performance criterion. The WTRU may transmit reporting information indicating the set of vector quantization codebooks and a quantized compressed CSI associated with the set of vector quantization codebooks.

Description

METHODS, ARCHITECTURES, APPARATUSES AND SYSTEMS FOR HYBRID VECTOR AND SCALAR QUANTIZATION FOR CHANNEL STATE INFORMATION COMPRESSION AND FEEDBACKCROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims the benefit of US Patent Application No. 63 / 609,361 filed December 13, 2023, which is incorporated herein by reference in its entirety.TECHNICAL FIELD

[0002] The present disclosure is generally directed to the fields of communications, software and encoding, including methods, architectures, apparatuses, and systems directed to hybrid vector and scalar quantization for channel state information (CSI) compression and feedback.BACKGROUND

[0003] The artificial intelligence / machine learning (AI / ML) framework for CSI compression may comprise a two-sided model, where the CSI compression may be performed at the wireless transmit and receive unit (WTRU) side, the compressed CSI may be fed back to the network (NW) and decompressed (restored) at the NW-side. Quantization-based approaches may be utilized to reduce the overhead associated with CSI feedback in AI / ML based CSI compression methods. Embodiments described herein have been designed with the foregoing in mind.SUMMARY

[0004] Methods, architectures, apparatuses, and systems directed to hybrid vector and scalar quantization for CSI compression and feedback are described herein. In an embodiment, a method implemented in a WTRU is described. The method may include receiving one or more reference signals and determining CSI based on the one or more reference signals. The method may include determining a (e.g., latent) vector based on a compression of the CSI and performing vector quantization of the (e.g., latent) vector for a plurality of sets of vector quantization codebooks, e.g., resulting in a plurality of quantized compressed CSI candidates, where a (e.g., each) quantized compressed CSI candidate may be associated with one set of vector quantization codebooks. The method may include selecting (1) a set of vector quantization codebooks from the plurality of sets of vector quantization codebooks and (2) a number of bits for scalar quantization based on any of a CSI feedback size and a reconstruction performance criterion. The method may include transmitting reporting information indicating the selected set of vector quantization codebooks of the plurality of quantized compressed CSI candidates and a quantized compressed CSI associated with the set of vector quantization codebooks.

[0005] In an embodiment, a WTRU is described. The WTRU may comprise circuitry including any of a transceiver, a processor, and memory. The WTRU may be configured to receive one or more reference signals and determine CSI based on the one or more reference signals. The WTRUmay be configured to determine a (e.g., latent) vector based on a compression of the CSI and perform vector quantization of the (e.g., latent) vector for a plurality of sets of vector quantization codebooks, e.g., resulting in a plurality of quantized compressed CSI candidates, where a (e.g., each) quantized compressed CSI candidate may be associated with one set of vector quantization codebooks. The WTRU may be configured to select (1) a set of vector quantization codebooks from the plurality of sets of vector quantization codebooks and (2) a number of bits for scalar quantization based on any of a CSI feedback size and a reconstruction performance criterion. The WTRU may be configured to transmit reporting information indicating the selected set of vector quantization codebooks of the plurality of quantized compressed CSI candidates and a quantized compressed CSI associated with the set of vector quantization codebooks.

[0006] In an embodiment, a method implemented in a network element is described. The method may include transmitting one or more reference signals to a WTRU and receiving from the WTRU, reporting information indicating a set of vector quantization codebooks of a plurality of sets of vector quantization codebooks, a quantized compressed channel state information (CSI) associated with the set of vector quantization codebooks and a number of bits used for scalar quantization. The method may include dequantizing the quantized compressed CSI based on the indicated set of vector quantization codebooks and the indicated number of bits used for scalar quantization. The method may include determining a CSI associated with the WTRU based on the dequantized compressed CSI.

[0007] In an embodiment, a network element is described. The network element may comprise circuitry including any of a transceiver, a processor, and memory. The network element may be configured to transmit one or more reference signals to a WTRU and receive from the WTRU, reporting information indicating a set of vector quantization codebooks of a plurality of sets of vector quantization codebooks, a quantized compressed channel state information (CSI) associated with the set of vector quantization codebooks and a number of bits used for scalar quantization. The network element may be configured to dequantize the quantized compressed CSI based on the indicated set of vector quantization codebooks and the indicated number of bits used for scalar quantization. The network element may be configured to determine a CSI associated with the WTRU based on the dequantized compressed CSI.BRIEF DESCRIPTION OF THE DRAWINGS

[0008] A more detailed understanding may be had from the detailed description below, given by way of example in conjunction with drawings appended hereto. Figures in such drawings, like the detailed description, are examples. As such, the Figures (FIGs.) and the detailed description arenot to be considered limiting, and other equally effective examples are possible and likely. Furthermore, like reference numerals ("ref.") in the FIGs. indicate like elements, and wherein:

[0009] FIG. 1 A is a system diagram illustrating an example communications system;

[0010] FIG. IB is a system diagram illustrating an example wireless transmit / receive unit (WTRU) that may be used within the communications system illustrated in FIG. 1 A;

[0011] FIG. 1C is a system diagram illustrating an example radio access network (RAN) and an example core network (CN) that may be used within the communications system illustrated in FIG. 1A;

[0012] FIG. ID is a system diagram illustrating a further example RAN and a further example CN that may be used within the communications system illustrated in FIG. 1 A;

[0013] FIG. 2 is a diagram illustrating an example of two-sided artificial intelligence / machine learning (AI / ML) based CSI compression framework;

[0014] FIG. 3 is a diagram illustrating an example of vector quantization (VQ) and dequantization;

[0015] FIG. 4 is a diagram illustrating an example of geometrical representation of vector quantization;

[0016] FIG. 5 is a diagram illustrating an example of VQ with a VQ codeword size being equal to the input data vector size;

[0017] FIG. 6 is a diagram illustrating an example set of VQ codebooks;

[0018] FIG. 7 is a diagram illustrating an example method for hybrid vector and scalar quantization of CSI feedback;

[0019] FIG. 8 is a diagram illustrating an example method for hybrid vector and scalar quantization of CSI feedback in a WTRU; and

[0020] FIG. 9 is a diagram illustrating an example method for hybrid vector and scalar quantization of CSI feedback in a network element.DETAILED DESCRIPTION

[0021] In the following detailed description, numerous specific details are set forth to provide a thorough understanding of embodiments and / or examples disclosed herein. However, it will be understood that such embodiments and examples may be practiced without some or all of the specific details set forth herein. In other instances, well-known methods, procedures, components and circuits have not been described in detail, so as not to obscure the following description. Further, embodiments and examples not specifically described herein may be practiced in lieu of, or in combination with, the embodiments and other examples described, disclosed or otherwise provided explicitly, implicitly and / or inherently (collectively "provided") herein. Although variousembodiments are described and / or claimed herein in which an apparatus, system, device, etc. and / or any element thereof carries out an operation, process, algorithm, function, etc. and / or any portion thereof, it is to be understood that any embodiments described and / or claimed herein assume that any apparatus, system, device, etc. and / or any element thereof is configured to carry out any operation, process, algorithm, function, etc. and / or any portion thereof.Example Communications System

[0022] The methods, apparatuses and systems provided herein are well-suited for communications involving both wired and wireless networks. An overview of various types of wireless devices and infrastructure is provided with respect to FIGs. 1A-1D, where various elements of the network may utilize, perform, be arranged in accordance with and / or be adapted and / or configured for the methods, apparatuses and systems provided herein.

[0023] FIG. 1A is a system diagram illustrating an example communications system 100 in which one or more disclosed embodiments may be implemented. The communications system 100 may be a multiple access system that provides content, such as voice, data, video, messaging, broadcast, etc., to multiple wireless users. The communications system 100 may enable multiple wireless users to access such content through the sharing of system resources, including wireless bandwidth. For example, the communications systems 100 may employ one or more channel access methods, such as code division multiple access (CDMA), time division multiple access (TDMA), frequency division multiple access (FDMA), orthogonal FDMA (OFDMA), singlecarrier FDMA (SC-FDMA), zero-tail (ZT) unique-word (UW) discrete Fourier transform (DFT) spread OFDM (ZT UW DTS-s OFDM), unique word OFDM (UW-OFDM), resource block- filtered OFDM, filter bank multicarrier (FBMC), and the like.

[0024] As shown in FIG. 1A, the communications system 100 may include wireless transmit / receive units (WTRUs) 102a, 102b, 102c, 102d, a radio access network (RAN) 104 / 113, a core network (CN) 106 / 115, a public switched telephone network (PSTN) 108, the Internet 110, and other networks 112, though it will be appreciated that the disclosed embodiments contemplate any number of WTRUs, base stations, networks, and / or network elements. Each of the WTRUs 102a, 102b, 102c, 102d may be any type of device configured to operate and / or communicate in a wireless environment. By way of example, the WTRUs 102a, 102b, 102c, 102d, any of which may be referred to as a "station" and / or a "STA", may be configured to transmit and / or receive wireless signals and may include (or be) a user equipment (UE), a mobile station, a fixed or mobile subscriber unit, a subscription-based unit, a pager, a cellular telephone, a personal digital assistant (PDA), a smartphone, a laptop, a netbook, a personal computer, a wireless sensor, a hotspot or Mi- Fi device, an Internet of Things (loT) device, a watch or other wearable, a head-mounted display(HMD), a vehicle, a drone, a medical device and applications (e.g., remote surgery), an industrial device and applications (e.g., a robot and / or other wireless devices operating in an industrial and / or an automated processing chain contexts), a consumer electronics device, a device operating on commercial and / or industrial wireless networks, and the like. Any of the WTRUs 102a, 102b, 102c and 102d may be interchangeably referred to as a UE.

[0025] The communications systems 100 may also include a base station 114a and / or a base station 114b. Each of the base stations 114a, 114b may be any type of device configured to wirelessly interface with at least one of the WTRUs 102a, 102b, 102c, 102d, e.g., to facilitate access to one or more communication networks, such as the CN 106 / 115, the Internet 110, and / or the networks 112. By way of example, the base stations 114a, 114b may be any of a base transceiver station (BTS), a Node-B (NB), an eNode-B (eNB), a Home Node-B (HNB), a Home eNode-B (HeNB), a gNode-B (gNB), a new radio (NR) Node-B (NR NB), a site controller, an access point (AP), a wireless router, and the like. While the base stations 114a, 114b are each depicted as a single element, it will be appreciated that the base stations 114a, 114b may include any number of interconnected base stations and / or network elements.

[0026] The base station 114a may be part of the RAN 104 / 113, which may also include other base stations and / or network elements (not shown), such as a base station controller (BSC), a radio network controller (RNC), relay nodes, etc. The base station 114a and / or the base station 114b may be configured to transmit and / or receive wireless signals on one or more carrier frequencies, which may be referred to as a cell (not shown). These frequencies may be in licensed spectrum, unlicensed spectrum, or a combination of licensed and unlicensed spectrum. A cell may provide coverage for a wireless service to a specific geographical area that may be relatively fixed or that may change over time. The cell may further be divided into cell sectors. For example, the cell associated with the base station 114a may be divided into three sectors. Thus, in an embodiment, the base station 114a may include three transceivers, i.e., one for each sector of the cell. In an embodiment, the base station 114a may employ multiple-input multiple output (MIMO) technology and may utilize multiple transceivers for each or any sector of the cell. For example, beamforming may be used to transmit and / or receive signals in desired spatial directions.

[0027] The base stations 114a, 114b may communicate with one or more of the WTRUs 102a, 102b, 102c, 102d over an air interface 116, which may be any suitable wireless communication link (e.g., radio frequency (RF), microwave, centimeter wave, micrometer wave, infrared (IR), ultraviolet (UV), visible light, etc.). The air interface 116 may be established using any suitable radio access technology (RAT).

[0028] More specifically, as noted above, the communications system 100 may be a multiple access system and may employ one or more channel access schemes, such as CDMA, TDMA,FDMA, OFDMA, SC-FDMA, and the like. For example, the base station 114a in the RAN 104 / 113 and the WTRUs 102a, 102b, 102c may implement a radio technology such as Universal Mobile Telecommunications System (UMTS) Terrestrial Radio Access (UTRA), which may establish the air interface 116 using wideband CDMA (WCDMA). WCDMA may include communication protocols such as High-Speed Packet Access (HSPA) and / or Evolved HSPA (HSPA+). HSPA may include High-Speed Downlink Packet Access (HSDPA) and / or High-Speed Uplink Packet Access (HSUPA).

[0029] In an embodiment, the base station 114a and the WTRUs 102a, 102b, 102c may implement a radio technology such as Evolved UMTS Terrestrial Radio Access (E-UTRA), which may establish the air interface 116 using Long Term Evolution (LTE) and / or LTE- Advanced (LTE-A) and / or LTE-Advanced Pro (LTE-A Pro).

[0030] In an embodiment, the base station 114a and the WTRUs 102a, 102b, 102c may implement a radio technology such as NR Radio Access, which may establish the air interface 116 using New Radio (NR).

[0031] In an embodiment, the base station 114a and the WTRUs 102a, 102b, 102c may implement multiple radio access technologies. For example, the base station 114a and the WTRUs 102a, 102b, 102c may implement LTE radio access and NR radio access together, for instance using dual connectivity (DC) principles. Thus, the air interface utilized by WTRUs 102a, 102b, 102c may be characterized by multiple types of radio access technologies and / or transmissions sent to / from multiple types of base stations (e.g., an eNB and a gNB).

[0032] In an embodiment, the base station 114a and the WTRUs 102a, 102b, 102c may implement radio technologies such as IEEE 802.11 (i.e., Wireless Fidelity (Wi-Fi), IEEE 802.16 (i.e., Worldwide Interoperability for Microwave Access (WiMAX)), CDMA2000, CDMA2000 IX, CDMA2000 EV-DO, Interim Standard 2000 (IS-2000), Interim Standard 95 (IS-95), Interim Standard 856 (IS-856), Global System for Mobile communications (GSM), Enhanced Data rates for GSM Evolution (EDGE), GSM EDGE (GERAN), and the like.

[0033] The base station 114b in FIG. 1 A may be a wireless router, Home Node-B, Home eNode- B, or access point, for example, and may utilize any suitable RAT for facilitating wireless connectivity in a localized area, such as a place of business, a home, a vehicle, a campus, an industrial facility, an air corridor (e.g., for use by drones), a roadway, and the like. In an embodiment, the base station 114b and the WTRUs 102c, 102d may implement a radio technology such as IEEE 802.11 to establish a wireless local area network (WLAN). In an embodiment, the base station 114b and the WTRUs 102c, 102d may implement a radio technology such as IEEE 802.15 to establish a wireless personal area network (WPAN). In an embodiment, the base station 114b and the WTRUs 102c, 102d may utilize a cellular-based RAT (e.g., WCDMA, CDMA2000,GSM, LTE, LTE-A, LTE-A Pro, NR, etc.) to establish any of a small cell, picocell or femtocell. As shown in FIG. 1 A, the base station 114b may have a direct connection to the Internet 110. Thus, the base station 114b may not be required to access the Internet 110 via the CN 106 / 115.

[0034] The RAN 104 / 113 may be in communication with the CN 106 / 115, which may be any type of network configured to provide voice, data, applications, and / or voice over internet protocol (VoIP) services to one or more of the WTRUs 102a, 102b, 102c, 102d. The data may have varying quality of service (QoS) requirements, such as differing throughput requirements, latency requirements, error tolerance requirements, reliability requirements, data throughput requirements, mobility requirements, and the like. The CN 106 / 115 may provide call control, billing services, mobile location-based services, pre-paid calling, Internet connectivity, video distribution, etc., and / or perform high-level security functions, such as user authentication. Although not shown in FIG. 1 A, it will be appreciated that the RAN 104 / 113 and / or the CN 106 / 115 may be in direct or indirect communication with other RANs that employ the same RAT as the RAN 104 / 113 or a different RAT. For example, in addition to being connected to the RAN 104 / 113, which may be utilizing an NR radio technology, the CN 106 / 115 may also be in communication with another RAN (not shown) employing any of a GSM, UMTS, CDMA 2000, WiMAX, E-UTRA, or Wi-Fi radio technology.

[0035] The CN 106 / 115 may also serve as a gateway for the WTRUs 102a, 102b, 102c, 102d to access the PSTN 108, the Internet 110, and / or other networks 112. The PSTN 108 may include circuit-switched telephone networks that provide plain old telephone service (POTS). The Internet 110 may include a global system of interconnected computer networks and devices that use common communication protocols, such as the transmission control protocol (TCP), user datagram protocol (UDP) and / or the internet protocol (IP) in the TCP / IP internet protocol suite. The networks 112 may include wired and / or wireless communications networks owned and / or operated by other service providers. For example, the networks 112 may include another CN connected to one or more RANs, which may employ the same RAT as the RAN 104 / 114 or a different RAT.

[0036] Some or all of the WTRUs 102a, 102b, 102c, 102d in the communications system 100 may include multi-mode capabilities (e.g., the WTRUs 102a, 102b, 102c, 102d may include multiple transceivers for communicating with different wireless networks over different wireless links). For example, the WTRU 102c shown in FIG. 1A may be configured to communicate with the base station 114a, which may employ a cellular-based radio technology, and with the base station 114b, which may employ an IEEE 802 radio technology.

[0037] FIG. IB is a system diagram illustrating an example WTRU 102. As shown in FIG. IB, the WTRU 102 may include a processor 118, a transceiver 120, a transmit / receive element 122, aspeaker / microphone 124, a keypad 126, a display / touchpad 128, non-removable memory 130, removable memory 132, a power source 134, a global positioning system (GPS) chipset 136, and / or other elements / peripherals 138, among others. It will be appreciated that the WTRU 102 may include any sub-combination of the foregoing elements while remaining consistent with an embodiment.

[0038] The processor 118 may be a general-purpose processor, a special purpose processor, a conventional processor, a digital signal processor (DSP), a plurality of microprocessors, one or more microprocessors in association with a DSP core, a controller, a microcontroller, Application Specific Integrated Circuits (ASICs), Field Programmable Gate Arrays (FPGAs) circuits, any other type of integrated circuit (IC), a state machine, and the like. The processor 118 may perform signal coding, data processing, power control, input / output processing, and / or any other functionality that enables the WTRU 102 to operate in a wireless environment. The processor 118 may be coupled to the transceiver 120, which may be coupled to the transmit / receive element 122. While FIG. IB depicts the processor 118 and the transceiver 120 as separate components, it will be appreciated that the processor 118 and the transceiver 120 may be integrated together, e.g., in an electronic package or chip.

[0039] The transmit / receive element 122 may be configured to transmit signals to, or receive signals from, a base station (e.g., the base station 114a) over the air interface 116. For example, in an embodiment, the transmit / receive element 122 may be an antenna configured to transmit and / or receive RF signals. In an embodiment, the transmit / receive element 122 may be an emitter / detector configured to transmit and / or receive IR, UV, or visible light signals, for example. In an embodiment, the transmit / receive element 122 may be configured to transmit and / or receive both RF and light signals. It will be appreciated that the transmit / receive element 122 may be configured to transmit and / or receive any combination of wireless signals.

[0040] Although the transmit / receive element 122 is depicted in FIG. IB as a single element, the WTRU 102 may include any number of transmit / receive elements 122. For example, the WTRU 102 may employ MIMO technology. Thus, in an embodiment, the WTRU 102 may include two or more transmit / receive elements 122 (e.g., multiple antennas) for transmitting and receiving wireless signals over the air interface 116.

[0041] The transceiver 120 may be configured to modulate the signals that are to be transmitted by the transmit / receive element 122 and to demodulate the signals that are received by the transmit / receive element 122. As noted above, the WTRU 102 may have multi-mode capabilities. Thus, the transceiver 120 may include multiple transceivers for enabling the WTRU 102 to communicate via multiple RATs, such as NR and IEEE 802.11, for example.

[0042] The processor 118 of the WTRU 102 may be coupled to, and may receive user input data from, the speaker / microphone 124, the keypad 126, and / or the display / touchpad 128 (e.g., a liquid crystal display (LCD) display unit or organic light-emitting diode (OLED) display unit). The processor 118 may also output user data to the speaker / microphone 124, the keypad 126, and / or the display / touchpad 128. In addition, the processor 118 may access information from, and store data in, any type of suitable memory, such as the non-removable memory 130 and / or the removable memory 132. The non-removable memory 130 may include random-access memory (RAM), readonly memory (ROM), a hard disk, or any other type of memory storage device. The removable memory 132 may include a subscriber identity module (SIM) card, a memory stick, a secure digital (SD) memory card, and the like. In other embodiments, the processor 118 may access information from, and store data in, memory that is not physically located on the WTRU 102, such as on a server or a home computer (not shown).

[0043] The processor 118 may receive power from the power source 134 and may be configured to distribute and / or control the power to the other components in the WTRU 102. The power source 134 may be any suitable device for powering the WTRU 102. For example, the power source 134 may include one or more dry cell batteries (e.g., nickel-cadmium (NiCd), nickel-zinc (NiZn), nickel metal hydride (NiMH), lithium-ion (Li-ion), etc.), solar cells, fuel cells, and the like.

[0044] The processor 118 may also be coupled to the GPS chipset 136, which may be configured to provide location information (e.g., longitude and latitude) regarding the current location of the WTRU 102. In addition to, or in lieu of, the information from the GPS chipset 136, the WTRU 102 may receive location information over the air interface 116 from a base station (e.g., base stations 114a, 114b) and / or determine its location based on the timing of the signals being received from two or more nearby base stations. It will be appreciated that the WTRU 102 may acquire location information by way of any suitable location-determination method while remaining consistent with an embodiment.

[0045] The processor 118 may further be coupled to other elements / peripherals 138, which may include one or more software and / or hardware modules / units that provide additional features, functionality and / or wired or wireless connectivity. For example, the elements / peripherals 138 may include an accelerometer, an e-compass, a satellite transceiver, a digital camera (e.g., for photographs and / or video), a universal serial bus (USB) port, a vibration device, a television transceiver, a hands free headset, a Bluetooth® module, a frequency modulated (FM) radio unit, a digital music player, a media player, a video game player module, an Internet browser, a virtual reality and / or augmented reality (VR / AR) device, an activity tracker, and the like. The elements / peripherals 138 may include one or more sensors, the sensors may be one or more of a gyroscope, an accelerometer, a hall effect sensor, a magnetometer, an orientation sensor, aproximity sensor, a temperature sensor, a time sensor; a geolocation sensor; an altimeter, a light sensor, a touch sensor, a magnetometer, a barometer, a gesture sensor, a biometric sensor, and / or a humidity sensor.

[0046] The WTRU 102 may include a full duplex radio for which transmission and reception of some or all of the signals (e.g., associated with particular subframes for both the uplink (e.g., for transmission) and downlink (e.g., for reception) may be concurrent and / or simultaneous. The full duplex radio may include an interference management unit to reduce and or substantially eliminate self-interference via either hardware (e.g., a choke) or signal processing via a processor (e.g., a separate processor (not shown) or via processor 118). In an embodiment, the WTRU 102 may include a half-duplex radio for which transmission and reception of some or all of the signals (e.g., associated with particular subframes for either the uplink (e.g., for transmission) or the downlink (e.g., for reception)).

[0047] FIG. 1C is a system diagram illustrating the RAN 104 and the CN 106 according to an embodiment. As noted above, the RAN 104 may employ an E-UTRA radio technology to communicate with the WTRUs 102a, 102b, and 102c over the air interface 116. The RAN 104 may also be in communication with the CN 106.

[0048] The RAN 104 may include eNode-Bs 160a, 160b, 160c, though it will be appreciated that the RAN 104 may include any number of eNode-Bs while remaining consistent with an embodiment. The eNode-Bs 160a, 160b, 160c may each include one or more transceivers for communicating with the WTRUs 102a, 102b, 102c over the air interface 116. In an embodiment, the eNode-Bs 160a, 160b, 160c may implement MIMO technology. Thus, the eNode-B 160a, for example, may use multiple antennas to transmit wireless signals to, and receive wireless signals from, the WTRU 102a.

[0049] Each of the eNode-Bs 160a, 160b, and 160c may be associated with a particular cell (not shown) and may be configured to handle radio resource management decisions, handover decisions, scheduling of users in the uplink (UL) and / or downlink (DL), and the like. As shown in FIG. 1C, the eNode-Bs 160a, 160b, 160c may communicate with one another over an X2 interface.

[0050] The CN 106 shown in FIG. 1C may include a mobility management entity (MME) 162, a serving gateway (SGW) 164, and a packet data network (PDN) gateway (PGW) 166. While each of the foregoing elements are depicted as part of the CN 106, it will be appreciated that any one of these elements may be owned and / or operated by an entity other than the CN operator.

[0051] The MME 162 may be connected to each of the eNode-Bs 160a, 160b, and 160c in the RAN 104 via an SI interface and may serve as a control node. For example, the MME 162 may be responsible for authenticating users of the WTRUs 102a, 102b, 102c, bearer activation / deactivation, selecting a particular serving gateway during an initial attach of theWTRUs 102a, 102b, 102c, and the like. The MME 162 may provide a control plane function for switching between the RAN 104 and other RANs (not shown) that employ other radio technologies, such as GSM and / or WCDMA.

[0052] The SGW 164 may be connected to each of the eNode-Bs 160a, 160b, 160c in the RAN 104 via the SI interface. The SGW 164 may generally route and forward user data packets to / from the WTRUs 102a, 102b, 102c. The SGW 164 may perform other functions, such as anchoring user planes during inter-eNode-B handovers, triggering paging when DL data is available for the WTRUs 102a, 102b, 102c, managing and storing contexts of the WTRUs 102a, 102b, 102c, and the like.

[0053] The SGW 164 may be connected to the PGW 166, which may provide the WTRUs 102a, 102b, 102c with access to packet-switched networks, such as the Internet 110, to facilitate communications between the WTRUs 102a, 102b, 102c and IP-enabled devices.

[0054] The CN 106 may facilitate communications with other networks. For example, the CN 106 may provide the WTRUs 102a, 102b, 102c with access to circuit-switched networks, such as the PSTN 108, to facilitate communications between the WTRUs 102a, 102b, 102c and traditional land-line communications devices. For example, the CN 106 may include, or may communicate with, an IP gateway (e.g., an IP multimedia subsystem (IMS) server) that serves as an interface between the CN 106 and the PSTN 108. In addition, the CN 106 may provide the WTRUs 102a, 102b, 102c with access to the other networks 112, which may include other wired and / or wireless networks that are owned and / or operated by other service providers.

[0055] Although the WTRU is described in FIGs. 1A-1D as a wireless terminal, it is contemplated that in certain representative embodiments that such a terminal may use (e.g., temporarily or permanently) wired communication interfaces with the communication network.

[0056] In representative embodiments, the other network 112 may be a WLAN.

[0057] A WLAN in infrastructure basic service set (BSS) mode may have an access point (AP) for the BSS and one or more stations (STAs) associated with the AP. The AP may have an access or an interface to a distribution system (DS) or another type of wired / wireless network that carries traffic into and / or out of the BSS. Traffic to STAs that originates from outside the BSS may arrive through the AP and may be delivered to the STAs. Traffic originating from STAs to destinations outside the BSS may be sent to the AP to be delivered to respective destinations. Traffic between STAs within the BSS may be sent through the AP, for example, where the source STA may send traffic to the AP and the AP may deliver the traffic to the destination STA. The traffic between STAs within a BSS may be considered and / or referred to as peer-to-peer traffic. The peer-to-peer traffic may be sent between (e.g., directly between) the source and destination STAs with a direct link setup (DLS). In certain representative embodiments, the DLS may use an 802. l ie DLS or an802.1 Iz tunneled DLS (TDLS). A WLAN using an Independent BSS (IBSS) mode may not have an AP, and the STAs (e.g., all of the STAs) within or using the IBSS may communicate directly with each other. The IBSS mode of communication may sometimes be referred to herein as an "ad-hoc" mode of communication.

[0058] When using the 802.1 lac infrastructure mode of operation or a similar mode of operations, the AP may transmit a beacon on a fixed channel, such as a primary channel. The primary channel may be a fixed width (e.g., 20 MHz wide bandwidth) or a dynamically set width via signaling. The primary channel may be the operating channel of the BSS and may be used by the STAs to establish a connection with the AP. In certain representative embodiments, Carrier sense multiple access with collision avoidance (CSMA / CA) may be implemented, for example in in 802.11 systems. For CSMA / CA, the STAs (e.g., every STA), including the AP, may sense the primary channel. If the primary channel is sensed / detected and / or determined to be busy by a particular STA, the particular STA may back off. One STA (e.g., only one station) may transmit at any given time in a given BSS.

[0059] High throughput (HT) STAs may use a 40 MHz wide channel for communication, for example, via a combination of the primary 20 MHz channel with an adjacent or nonadj acent 20 MHz channel to form a 40 MHz wide channel.

[0060] Very high throughput (VHT) STAs may support 20 MHz, 40 MHz, 80 MHz, and / or 160 MHz wide channels. The 40 MHz, and / or 80 MHz, channels may be formed by combining contiguous 20 MHz channels. A 160 MHz channel may be formed by combining 8 contiguous 20 MHz channels, or by combining two non-contiguous 80 MHz channels, which may be referred to as an 80+80 configuration. For the 80+80 configuration, the data, after channel encoding, may be passed through a segment parser that may divide the data into two streams. Inverse fast fourier transform (IFFT) processing, and time domain processing, may be done on each stream separately. The streams may be mapped on to the two 80 MHz channels, and the data may be transmitted by a transmitting STA. At the receiver of the receiving STA, the above-described operation for the 80+80 configuration may be reversed, and the combined data may be sent to a medium access control (MAC) layer, entity, etc.

[0061] Sub 1 GHz modes of operation are supported by 802.1 laf and 802.11 ah. The channel operating bandwidths, and carriers, are reduced in 802.1 laf and 802.1 lah relative to those used in802.1 In, and 802.1 lac. 802.1 laf supports 5 MHz, 10 MHz and 20 MHz bandwidths in the TV white space (TVWS) spectrum, and 802.1 lah supports 1 MHz, 2 MHz, 4 MHz, 8 MHz, and 16 MHz bandwidths using non-TVWS spectrum. According to a representative embodiment,802.1 lah may support meter type control / machine-type communications (MTC), such as MTC devices in a macro coverage area. MTC devices may have certain capabilities, for example, limitedcapabilities including support for (e.g., only support for) certain and / or limited bandwidths. The MTC devices may include a battery with a battery life above a threshold (e.g., to maintain a very long battery life).

[0062] WLAN systems, which may support multiple channels, and channel bandwidths, such as 802.1 In, 802.1 lac, 802.11af, and 802.1 lah, include a channel which may be designated as the primary channel. The primary channel may have a bandwidth equal to the largest common operating bandwidth supported by all STAs in the BSS. The bandwidth of the primary channel may be set and / or limited by a STA, from among all STAs in operating in a BSS, which supports the smallest bandwidth operating mode. In the example of 802.1 lah, the primary channel may be 1 MHz wide for STAs (e.g., MTC type devices) that support (e.g., only support) a 1 MHz mode, even if the AP, and other STAs in the BSS support 2 MHz, 4 MHz, 8 MHz, 16 MHz, and / or other channel bandwidth operating modes. Carrier sensing and / or network allocation vector (NAV) settings may depend on the status of the primary channel. If the primary channel is busy, for example, due to a STA (which supports only a 1 MHz operating mode), transmitting to the AP, the entire available frequency bands may be considered busy even though a majority of the frequency bands remains idle and may be available.

[0063] In the United States, the available frequency bands, which may be used by 802.1 lah, are from 902 MHz to 928 MHz. In Korea, the available frequency bands are from 917.5 MHz to 923.5 MHz. In Japan, the available frequency bands are from 916.5 MHz to 927.5 MHz. The total bandwidth available for 802.1 lah is 6 MHz to 26 MHz depending on the country code.

[0064] FIG. ID is a system diagram illustrating the RAN 113 and the CN 115 according to an embodiment. As noted above, the RAN 113 may employ an NR radio technology to communicate with the WTRUs 102a, 102b, 102c over the air interface 116. The RAN 113 may also be in communication with the CN 115.

[0065] The RAN 113 may include gNBs 180a, 180b, 180c, though it will be appreciated that the RAN 113 may include any number of gNBs while remaining consistent with an embodiment. The gNBs 180a, 180b, 180c may each include one or more transceivers for communicating with the WTRUs 102a, 102b, 102c over the air interface 116. In an embodiment, the gNBs 180a, 180b, 180c may implement MIMO technology. For example, gNBs 180a, 180b may utilize beamforming to transmit signals to and / or receive signals from the WTRUs 102a, 102b, 102c. Thus, the gNB 180a, for example, may use multiple antennas to transmit wireless signals to, and / or receive wireless signals from, the WTRU 102a. In an embodiment, the gNBs 180a, 180b, 180c may implement carrier aggregation technology. For example, the gNB 180a may transmit multiple component carriers to the WTRU 102a (not shown). A subset of these component carriers may be on unlicensed spectrum while the remaining component carriers may be on licensed spectrum. Inan embodiment, the gNBs 180a, 180b, 180c may implement Coordinated Multi-Point (CoMP) technology. For example, WTRU 102a may receive coordinated transmissions from gNB 180a and gNB 180b (and / or gNB 180c).

[0066] The WTRUs 102a, 102b, 102c may communicate with gNBs 180a, 180b, 180c using transmissions associated with a scalable numerology. For example, OFDM symbol spacing and / or OFDM subcarrier spacing may vary for different transmissions, different cells, and / or different portions of the wireless transmission spectrum. The WTRUs 102a, 102b, 102c may communicate with gNBs 180a, 180b, 180c using subframe or transmission time intervals (TTIs) of various or scalable lengths (e.g., including a varying number of OFDM symbols and / or lasting varying lengths of absolute time).

[0067] The gNBs 180a, 180b, 180c may be configured to communicate with the WTRUs 102a, 102b, 102c in a standalone configuration and / or a non-standalone configuration. In the standalone configuration, WTRUs 102a, 102b, 102c may communicate with gNBs 180a, 180b, 180c without also accessing other RANs (e.g., such as eNode-Bs 160a, 160b, 160c). In the standalone configuration, WTRUs 102a, 102b, 102c may utilize one or more of gNBs 180a, 180b, 180c as a mobility anchor point. In the standalone configuration, WTRUs 102a, 102b, 102c may communicate with gNBs 180a, 180b, 180c using signals in an unlicensed band. In a non-standalone configuration WTRUs 102a, 102b, 102c may communicate with / connect to gNBs 180a, 180b, 180c while also communicating with / connecting to another RAN such as eNode-Bs 160a, 160b, 160c. For example, WTRUs 102a, 102b, 102c may implement DC principles to communicate with one or more gNBs 180a, 180b, 180c and one or more eNode-Bs 160a, 160b, 160c substantially simultaneously. In the non-standalone configuration, eNode-Bs 160a, 160b, 160c may serve as a mobility anchor for WTRUs 102a, 102b, 102c and gNBs 180a, 180b, 180c may provide additional coverage and / or throughput for servicing WTRUs 102a, 102b, 102c.

[0068] Each of the gNBs 180a, 180b, 180c may be associated with a particular cell (not shown) and may be configured to handle radio resource management decisions, handover decisions, scheduling of users in the UL and / or DL, support of network slicing, dual connectivity, interworking between NR and E-UTRA, routing of user plane data towards user plane functions (UPFs) 184a, 184b, routing of control plane information towards access and mobility management functions (AMFs) 182a, 182b, and the like. As shown in FIG. ID, the gNBs 180a, 180b, 180c may communicate with one another over an Xn interface.

[0069] The CN 115 shown in FIG. ID may include at least one AMF 182a, 182b, at least one UPF 184a, 184b, at least one session management function (SMF) 183a, 183b, and at least one Data Network (DN) 185a, 185b. While each of the foregoing elements are depicted as part of theCN 115, it will be appreciated that any of these elements may be owned and / or operated by an entity other than the CN operator.

[0070] The AMF 182a, 182b may be connected to one or more of the gNBs 180a, 180b, 180c in the RAN 113 via an N2 interface and may serve as a control node. For example, the AMF 182a, 182b may be responsible for authenticating users of the WTRUs 102a, 102b, 102c, support for network slicing (e.g., handling of different protocol data unit (PDU) sessions with different requirements), selecting a particular SMF 183a, 183b, management of the registration area, termination of non-access stratum (NAS) signaling, mobility management, and the like. Network slicing may be used by the AMF 182a, 182b, e.g., to customize CN support for WTRUs 102a, 102b, 102c based on the types of services being utilized by WTRUs 102a, 102b, 102c. For example, different network slices may be established for different use cases such as services relying on ultra-reliable low latency (URLLC) access, services relying on enhanced massive mobile broadband (eMBB) access, services for MTC access, and / or the like. The AMF 182a, 182b may provide a control plane function for switching between the RAN 113 and other RANs (not shown) that employ other radio technologies, such as LTE, LTE-A, LTE-A Pro, and / or non-3GPP access technologies such as Wi-Fi.

[0071] The SMF 183a, 183b may be connected to an AMF 182a, 182b in the CN 115 via an N11 interface. The SMF 183a, 183b may also be connected to a UPF 184a, 184b in the CN 115 via an N4 interface. The SMF 183a, 183b may select and control the UPF 184a, 184b and configure the routing of traffic through the UPF 184a, 184b. The SMF 183a, 183b may perform other functions, such as managing and allocating UE IP address, managing PDU sessions, controlling policy enforcement and QoS, providing downlink data notifications, and the like. A PDU session type may be IP -based, non-IP based, Ethernet-based, and the like.

[0072] The UPF 184a, 184b may be connected to one or more of the gNBs 180a, 180b, 180c in the RAN 113 via an N3 interface, which may provide the WTRUs 102a, 102b, 102c with access to packet-switched networks, such as the Internet 110, e.g., to facilitate communications between the WTRUs 102a, 102b, 102c and IP-enabled devices. The UPF 184a, 184b may perform other functions, such as routing and forwarding packets, enforcing user plane policies, supporting multihomed PDU sessions, handling user plane QoS, buffering downlink packets, providing mobility anchoring, and the like.

[0073] The CN 115 may facilitate communications with other networks. For example, the CN 115 may include, or may communicate with, an IP gateway (e.g., an IP multimedia subsystem (IMS) server) that serves as an interface between the CN 115 and the PSTN 108. In addition, the CN 115 may provide the WTRUs 102a, 102b, 102c with access to the other networks 112, which may include other wired and / or wireless networks that are owned and / or operated by other serviceproviders. In an embodiment, the WTRUs 102a, 102b, 102c may be connected to a local Data Network (DN) 185a, 185b through the UPF 184a, 184b via the N3 interface to the UPF 184a, 184b and an N6 interface between the UPF 184a, 184b and the DN 185a, 185b.

[0074] In view of FIGs. 1 A-1D, and the corresponding description of FIGs. 1 A-1D, one or more, or all, of the functions described herein with regard to any of WTRUs 102a-d, base stations 114a- b, eNode-Bs 160a-c, MME 162, SGW 164, PGW 166, gNBs 180a-c, AMFs 182a-b, UPFs 184a- b, SMFs 183a-b, DNs 185a-b, and / or any other element(s) / device(s) described herein, may be performed by one or more emulation elements / devices (not shown). The emulation devices may be one or more devices configured to emulate one or more, or all, of the functions described herein. For example, the emulation devices may be used to test other devices and / or to simulate network and / or WTRU functions.

[0075] The emulation devices may be designed to implement one or more tests of other devices in a lab environment and / or in an operator network environment. For example, the one or more emulation devices may perform the one or more, or all, functions while being fully or partially implemented and / or deployed as part of a wired and / or wireless communication network in order to test other devices within the communication network. The one or more emulation devices may perform the one or more, or all, functions while being temporarily implemented / deployed as part of a wired and / or wireless communication network. The emulation device may be directly coupled to another device for purposes of testing and / or may performing testing using over-the-air wireless communications.

[0076] The one or more emulation devices may perform the one or more, including all, functions while not being implemented / deployed as part of a wired and / or wireless communication network. For example, the emulation devices may be utilized in a testing scenario in a testing laboratory and / or a non-deployed (e.g., testing) wired and / or wireless communication network in order to implement testing of one or more components. The one or more emulation devices may be test equipment. Direct RF coupling and / or wireless communications via RF circuitry (e.g., which may include one or more antennas) may be used by the emulation devices to transmit and / or receive data.

[0077] Throughout embodiments described herein the terms "base station", "network", and "gNB", collectively "the network" may be used interchangeably to designate any network element such as e.g., a network element acting as a serving base station. Embodiments described herein are not limited to gNBs and are applicable to any other type of base stations.

[0078] For the sake of clarity, satisfying, failing to satisfy a condition, and configuring condition parameter(s) are described throughout embodiments described herein as relative to a threshold (e.g., greater, or lower than) a (e.g., threshold) value, configuring the (e.g., threshold) value, etc.For example, satisfying a condition may be described as being above a (e.g., threshold) value, and failing to satisfy a condition may be described as being below a (e.g., threshold) value. Embodiments described herein are not limited to threshold-based conditions. Any kind of other condition and param eter(s) (such as e.g., belonging or not belonging to a range of values) may be applicable to embodiments described herein.

[0079] Throughout embodiments described herein, (e.g., configuration) information may be described as received by a WTRU from the network, for example, through system information or via any kind of protocol message. Although not explicitly mentioned throughout embodiments described herein, the same (e.g., configuration) information may be pre-configured in the WTRU (e.g., via any kind of pre-configuration methods such as e.g., via factory settings), such that this (e.g., configuration) information may be used by the WTRU without being received from the network.

[0080] Throughout embodiments described herein, the expression "the WTRU may be configured with a set of parameters" is equivalent or may be used interchangeably with "the WTRU may receive configuration information (e.g., from another network element (e.g., gNB)) indicating a set of parameters". Throughout embodiments described herein, the expressions "the WTRU may report something", and "the WTRU may be configured to report something", is equivalent or may be used interchangeably with "the WTRU may transmit (e.g., reporting) information indicating something".

[0081] Throughout embodiments described herein, the expressions "the WTRU may be signaled a parameter” and "the WTRU may be indicated with a parameter” are equivalent or may be used interchangeably with "the WTRU may receive information (e.g., from another network element (e.g., gNB)) indicating a parameter".

[0082] Throughout embodiments described herein, the expression "the WTRU may be indicated to perform an action” is equivalent or may be used interchangeably with "the WTRU may receive information (e.g., from another network element (e.g., gNB)) indicating to perform an action".

[0083] In embodiments described herein, "a" and "an" and similar phrases are to be interpreted as "one or more" and "at least one". Similarly, any term which ends with the suffix "(s)" is to be interpreted as "one or more" and "at least one". The term "may" is to be interpreted as "may, for example".

[0084] A symbol " / " (e.g., forward slash) may be used herein to represent "and / or", where for example, "A / B" may imply "A and / or B".

[0085] In embodiments described herein, "list of', "set of' and "one or more of' may be used interchangeably.

[0086] In embodiments described herein, "identity" and "identifier" may be used interchangeably to refer to how a network element (or a WTRU) may be identified.

[0087] In embodiments described herein, a network element may refer to any kind of device including computing resources and networking capabilities, that may be connected to a network. The terms network element and node may be used interchangeably. A network element may be any kind of network infrastructure device and or a WTRU. The architecture depicted at FIG. IB for a WTRU 102 may be applicable more generally to any kind of network element.Overview

[0088] For WTRUs capable of performing vector quantization for (e.g., AI / ML-based) CSI compression, there are described herein WTRU methods to select vector quantization codebooks and to determine the number of bits for scalar quantization for a hybrid vector and scalar quantization mode of operation.Autoencoder based CSI Compression

[0089] An AI / ML framework for CSI compression may comprise a two-sided model, where the CSI compression may be performed at the WTRU side, the compressed CSI may be fed back to the network (NW) and decompressed (restored) at the NW-side. The WTRU side processing for CSI compression may comprise a ML encoder (e.g., preceded by a pre-processing stage). The NW side processing may comprise a ML decoder (e.g., followed by a post-processing stage if preprocessing is employed at the WTRU). The ML encoder operating in conjunction with a corresponding machine learning (ML) decoder are referred to herein as an autoencoder (AE).

[0090] FIG. 2 is a diagram illustrating an example of two-sided AI / ML based CSI compression framework. The ML encoder 21 and ML decoder 22 part of the AE may be trained separately or jointly, using a training dataset. In an example, training of the ML models may be performed offline, e.g., prior to deploying the models at the network elements (WTRUs and / or gNB).Quantization

[0091] Any of trainable and fixed quantization-based approaches may be utilized to reduce the overhead associated with CSI feedback in AI / ML based CSI compression methods. Quantization schemes may be divided into, for example, two categories (1) scalar quantization (SQ), where an (e.g., each) individual dimension of the compressed CSI (latent) may be independently quantized or (2) vector quantization (VQ).

[0092] In vector quantization, the input data vector to be quantized may be compared to a (e.g., each) codeword in a vector quantization codebook (VQ codebook).

[0093] FIG. 3 is a diagram illustrating an example of vector quantization and dequantization. The quantized output vector may be selected as the codeword closest to the input data vector 31. TheVQ codebook 331, 341 may be available at the transmit network element 33 (where quantization may be performed) and at the receiver network element 34 (where dequantization may be performed), the de-quantizer may be signaled (e.g., indicated) the index of the closest codeword within the VQ codebook, which may reduce the feedback overhead.

[0094] In a geometrical interpretation of the vector quantization, the codewords in the VQ codebook may correspond to the centroids of the clusters of the data distribution.

[0095] FIG. 4 is a diagram illustrating an example of geometrical representation of vector quantization. The data vector 41, which may be referred to herein as z may be within a cluster 42 which may be referred to herein as k, and may be approximated (e.g., quantized) to the cluster center (centroid) 43, which may be codeword Ckof the VQ codebook. The closer the data vector 41 z may be to the cluster center 43, the smaller the quantization error. The farther the data vector 41 z may be to the cluster center 43, the larger the quantization error. The distance between the data vector 41 z and the cluster center 43 may determine (e.g., represent, be associated with) the quantization error.

[0096] FIG. 5 is a diagram illustrating an example of VQ with a VQ codeword size being equal to the input data vector size. The vector quantization may compare the input data vector z to a (e.g., each) codeword (vector) of the VQ codebook CvC2, ... CN. The size of (e.g., all) the codewords in the VQ codebook may be equal to the size, D, of the input data vector z. In this example, the (e.g., entire) input data vector may be quantized in one step, by comparing with a (e.g., every) codeword in the VQ codebook.

[0097] There may be other examples of VQ, where parts of the input data vector z may be quantized using VQ codebooks with VQ codeword length shorter than the input data vector size. In this example, multiple component VQ codebooks may be used for quantization, where a (e.g., each) VQ codebook may be used to quantize a part of the input data vector, and the final quantized vector may be a concatenation of the closest codewords of the component VQ codebooks, as illustrated in FIG. 6.

[0098] FIG. 6 is a diagram illustrating an example set of VQ codebooks. The sum of the codeword lengths of the component VQ codebooks may be equal to the size of the input data vector 60 to be quantized, such as e.g.,+ B2= D. To reconstruct the input data vector 60, the de-quantizer may be signaled (e.g., indicated) the index of the closest codeword within a (e.g., each) component codebooks, for example, index k for a first VQ codebook 61, and index k2for a second VQ codebook 62 as illustrated in FIG. 6. The de-quantizer may concatenate the corresponding (closest) codewords, codeword Clkifrom the first VQ codebook 61, and codeword C2fcfromthe second VQ codebook 62 to determine the reconstructed data vector C, as follows:

[0099] In one example for FIG. 6, for an input vector of size D=16, two VQ codebooks may be used, where the first VQ codebook size may be 256 with a VQ codeword size of 8 bits, and a second VQ codebook size of 128 with a VQ codeword size of 8 bits, as follows:256, Bi = 8, log2V1= 8), VQ CB2 N2= 128, B2= 8, log2V2= 7)

[0100] The feedback overhead for this example may be:+ log2N2= 8 + 7 = 15 bits.

[0101] In another example for FIG. 6 for an input vector of size D=16, two VQ codebooks may be used, where the first VQ codebook size may be 512 with a VQ codeword size of 10 bits, and a second VQ codebook size of 256 with a VQ codeword size of 6 bits, as follows:256, B2= 6, log2V2= 8)

[0102] The feedback overhead for this example may be:+ log2N2= 9 + 8 = 17 bits.

[0103] Using (e.g., only) scalar quantization may result in low reconstruction performance (e.g., if a smaller number of bits is used for SQ), and / or in high overhead (e.g., if a larger number of bits is used for SQ). Training-aware vector quantization (VQ) may provide better performance compared to SQ, and may result in higher storage and computational complexity, for example, for large VQ codebooks.

[0104] Embodiments described herein may allow to reduce the CSI feedback overhead while maintaining a target reconstruction performance based on determining and adapting parameters of hybrid vector and scalar quantization.Hybrid Vector and Scalar Quantization Overview

[0105] A WTRU capable of performing hybrid VQ and SQ quantization may be configured with one or more sets of VQ codebooks. The WTRU may determine any of the VQ codebook set and the SQ parameters as a function of any of CSI feedback (e.g., size) information and configured reconstruction performance information (e.g., threshold).

[0106] In an embodiment, a WTRU capable of performing hybrid vector and scalar quantization (e.g., for AI / ML based CSI compression) may be configured with a plurality of sets of VQ codebooks.

[0107] In an example, the WTRU may receive from the NW (e.g., configuration information indicating) the configuration for the metric and the corresponding thresholds to evaluate the CSI reconstruction performance.

[0108] In an example, the WTRU may receive one or more (e.g., CSI) reference signals (RS).

[0109] In an example, the WTRU may determine the CSI based on the received (e.g., CSI) reference signals, where the CSI may be represented as the channel matrix (H) or the eigenvectorsof the channel matrix. The WTRU may compress the CSI and may determine the latent vector z corresponding to the measured channel H (e.g., using a configured AI / ML encoder model).

[0110] In an example, the WTRU may perform vector quantization of the latent vector z for a (e.g., each configured) set of VQ codebooks (e.g., sets that may meet the configured CSI feedback size). The WTRU may obtain different quantized vectors of the latent vector for different sets of VQ codebooks (e.g., sets that may meet the configured CSI feedback size).[OHl] In an example, the WTRU may select any of the set of VQ codebooks and the number of bits for SQ as a function of a (e.g., configured) CSI feedback size and / or a (e.g., configured) reconstruction performance criterion (e.g., threshold).

[0112] In an example, the WTRU may report any of the selected set of VQ codebooks, the number of bits for SQ and the quantized compressed CSI (e.g., the quantized vector of the latent vector obtained based on the selected set of VQ codebooks).Terminology

[0113] Throughout embodiments described herein the terms "hybrid CSI feedback report", "CSI feedback report", and "CSI feedback", collectively "reporting information" may be used interchangeably to designate any piece of information (e.g., message) that may be transmitted by the WTRU to the gNB to provide information related to CSI.

[0114] A VQ codebook may be referred to herein as a set of vectors (codewords) of the same size, that may be used to quantize a data vector z of size D. For AE-based CSI compression applications, the data vector z may represent the compressed output of the AI / ML encoder (also referred to herein as the latent vector, or output of the bottleneck layer). The terms "bottleneck size", and "(e.g., latent, data) vector size" may be used interchangeably to designate the size (e.g., the dimensionality, (D)) of the vector z to be quantized.

[0115] VQ codebook size, N, may be referred to herein as the number of entries (e.g., elements) in the codebook, where an (e.g., each) element may be referred to as a vector or a codeword. The terms VQ codebook size and codebook size may be used interchangeably.

[0116] n-bit VQ codebook may be referred to herein as the number of bits to represent the size of the VQ codebook. For example, for a VQ codebook of size N, n = log2N bits may be used to represent the size of the index for indexing the codewords in the codebook. The number of bits to represent the size of the VQ codebook may reflect the overhead associated with feeding back (e.g., transmitting) the quantized data vector, which may be indicated by the index of the closest codeword to the input data vector z. The terms n-bit VQ codebook and n-bit codebook may be used interchangeably. If the codebook size is a power of 2, a VQ codebook may be referred interchangeably as a n-bit (VQ) codebook or a (VQ) codebook of size N.

[0117] VQ vector size / VQ codeword size, B may be referred to herein as the length of a (e.g., each) vector of a (e.g., VQ) codebook. For (e.g., traditional) vector quantization, the vector size of the VQ codebook may be equal to the size of the data vector z to be quantized, such as e.g., B=D.

[0118] A quantization mode may indicate the process used to quantize the data vector z, which may be any of (i) scalar quantization SQ (uniform, or non-uniform), (ii) vector quantization (VQ), and (iii) hybrid VQ and SQ quantization.

[0119] A set of VQ codebooks may be referred to herein as a set of VQ codebooks comprising one or more VQ codebooks. For a single codebook per set, the size of the codebook vectors, B, may be equal to the input data vector size D. For multiple (M) codebooks (CB) per set, such as CBltCB2, ...=D, where Bkmay be the vector size or codeword size associated with the codebook CBk. The component codebooks of the set of VQ codebooks may have the same or may have different sizes: N N2, ... NMwhere Nkmay be the VQ codebook size of CBk.

[0120] Residual vector, Rp: for p-th codebook set, with the overall selected codeword indicated as Cp, where the super-script may refer to the VQ codebook set and the sub-script k may refer to the selected codeword index, the residual vector may be determined as the difference between the data vector z and the selected (codeword) Cp, determined as: Rp= z — Cp.

[0121] Using the terminology described herein, a single VQ codebook may be characterized by (e.g., associated with) a VQ codebook size, a VQ codeword size, and feedback overhead (e.g., [N, B, n (where n = log2N)]).

[0122] Using the terminology described herein, a set of VQ codebooks may be characterized by (e.g., associated with) the following parameters: [M, (N1, B1, og2N1), ... (NM, BM, log21VM)] representing: the number of codebooks in the set, CB (codebook size, vector size, feedback overhead), ... CBM(codebook size, VQ codeword size, feedback overhead)). A set of VQ codebooks may be characterized by (e.g., associated with) the number of codebooks in the set, and for the different codebooks in the set: the codebook size, the vector size and the feedback overhead.

[0123] The feedback overhead associated with a set of VQ codebooks may be constant (e.g., fixed) regardless of the individual codeword(s) the input data vector z may be quantized to. The overhead associated with a set of VQ codebooks may be the sum of overheads of the component codebooks, which may be referred to herein as ”=1log2 k■

[0124] The hybrid vector and scalar quantization mode may comprise applying vector quantization to the data (e.g., latent) vector z using the (e.g., configured) VQ codebook(s), determining the candidate quantized vector, calculating the associated residual vector, determining the number of bits for SQ, and using scalar quantization for the residual vector. Considering thatscalar quantization may be applied to an (e.g., each) element of the residual vector, the total number of bits for SQ may be an integer multiple of the input data vector size, D, as described herein.

[0125] Embodiments described herein may be applicable for different VQ configurations for the WTRU, such as, for example, any of (i) a single set of VQ codebooks, comprising a single VQ codebook (e.g., as shown in FIG. 5), (ii) a single set of VQ codebooks, wherein the set may comprise multiple VQ codebooks (as shown in FIG. 6), and (iii) a plurality of sets of VQ codebooks, wherein a set of VQ codebooks may comprise one or more VQ codebooks (generalization of the example shown in FIG. 6).

[0126] In embodiments described herein, the terms quantized compressed CSI candidate and candidate quantized vector may be used interchangeably.Hybrid Vector and Scalar Quantization

[0127] Hybrid vector and scalar quantization is described herein.Configuration of WTRU Quantizer

[0128] The configuration of the quantizer at the WTRU is described herein.Configuration of AI / ML Model with Multiple Quantization Modes

[0129] A WTRU may (e.g., be configured to) generate one or more quantity associated with the CSI feedback report using an AI / ML model, such as e.g., configured autoencoder (AE) model. The configured AI / ML encoder model may be trained to generate a latent output (e.g., expressed in floating point) which may be post-processed (e.g., quantized) into a stream of bits that may be sent to the NW for reconstructing the channel using the AI / ML decoder. In an example, to quantize the output latent of the AI / ML encoder, the WTRU may be explicitly configured with (e.g., by receiving configuration information indicating) one of three quantization modes: scalar quantization (SQ), vector quantization (VQ), hybrid quantization (SQ+VQ). In another example, the WTRU may be implicitly configured with the quantization mode, e.g., as a function of any of the configured sub-bands, input dimension, carrier frequency, indicated model ID, etc. The WTRU may use the configured quantization mode to encode the output latent to the (e.g., expected) number of bits. The quantization mode may be indicated (to the NW) through any of a MAC control element (MAC-CE) or as a two-bit field in the downlink control information (DCI).

[0130] In an example, the WTRU may be configured with one or more parameters based on the configured quantization mode. For example, if the WTRU is configured with the scalar quantization mode, then the WTRU may be indicated any of the scalar quantization type, e.g., uniform or non-uniform, and the number of bits to use per latent element. For example, if theWTRU is configured with the hybrid quantization mode, then the WTRU may be configured with any of a set of VQ codebooks, a VQ set selection flag, a VQ bit budget, a SQ bit budget, and a VQ+SQ bit budget / total feedback size (Fs).

[0131] In an example, the WTRU may be configured with a set of VQ codebooks. This may be implicitly indicated as a function of any of the AI / ML model, the bottleneck size, the number of antennas, a rank, a CSI configuration, etc. In another example, the set of VQ codebooks may be explicitly configured (e.g., indicated) with one or more of (i) the number of codebook sets, e.g., (P), which may indicate the total number of sets that the WTRU may select from for performing the vector quantization, and (ii) the identities of the configured number of sets. A (e.g., each) set identifier (ID) may have (e.g., be associated with) a predefined set of parameters which may include any of the number of codebooks in the set (M), the size of the m-th codebook (lVm), the codeword size in the m-th codebook (Bm), and the overhead associated with the m-th set

[0132] In an example, the WTRU may be configured with a VQ set selection flag. If activated, the WTRU may select and report one of the P configured sets of VQ codebooks.

[0133] In an example, the WTRU may be configured with a VQ bit budget, indicating the allocated bit budget for reporting the VQ parameters (e.g., the selected codewords).

[0134] In an example, the WTRU may be configured with a SQ bit budget, indicating the allocated bit budget for quantizing the residual vector using scalar quantization. This may be indicated in terms of the number of bits that the WTRU may use for a (e.g., each) element of the residual vector.

[0135] In an example, the WTRU may be configured with a VQ+SQ bit budget (e.g., total feedback size (FQ) indicating the allocated bit budget for quantizing the residual vector using scalar quantization and vector quantization. The WTRU may determine the split between the bits used for SQ and bits used for VQ.

[0136] Any of the VQ related parameters described hereabove may also be used if the WTRU is configured with the VQ quantization mode.Configuration of Performance Metrics

[0137] In an example, the WTRU may be configured or indicated to select (e.g., determine) and / or report the (e.g., preferred) quantization mode. In an example, the WTRU may be indicated to determine a (e.g., preferred) set of VQ codebook associated with the VQ or the hybrid quantization modes. The WTRU may be configured with assistance information to determine the set of VQ codebooks. For example, the WTRU may be configured with one or more performance metric threshold(s). For example, the metric M(-,-) may be any of a squared generalized cosine similarity (SGCS), a normalized mean squared error (NMSE), a distance, a normalized distance,and a quantization error. The WTRU may be indicated with a first (e.g., metric) criterion (e.g., threshold) to control the VQ error and a second (e.g., metric) criterion (e.g., threshold) to control the SQ error associated with the residual part. In an example, the WTRU may be configured with a criterion (e.g., threshold) on the overall hybrid VQ+SQ error.

[0138] In various embodiments, the different pieces of configuration information described herein related the configuration of the AI / ML model with multiple quantization modes and the configuration of performance metrics may be received by the WTRU (e.g., if any) in different configuration messages (e.g., transmissions) or in a same configuration message (e.g., transmission).WTRU Determination of VQ and SQ Parameters

[0139] The determination by the WTRU of any of VQ and SQ parameters is described herein.WTRU Determination of the Quantization Mode

[0140] A WTRU may be configured with one or more sets of VQ codebooks. The WTRU may determine the quantization mode, e.g., as a function of any of the CSI feedback size and the (e.g., configured) AI / ML encoder model.

[0141] In an example, the WTRU may determine the (e.g., total) number of bits available for SQ corresponding to a (e.g., each) configured set of VQ codebooks, for example, as the difference between the configured CSI feedback size and the overhead of the set of VQ codebooks. The WTRU may determine “hybrid VQ+SQ” as the quantization mode when at least for one of the configured sets of VQ codebooks, the (e.g., total) number of bits available for SQ is greater than the bottleneck size of the (e.g., configured) AI / ML encoder model. The WTRU may determine “VQ” as the quantization mode, e.g., when the (e.g., total) number of bits available for SQ for (e.g., each of) the configured sets of VQ codebooks is smaller than the (e.g., configured) AI / ML encoder model bottleneck size.

[0142] The WTRU may use the determined quantization mode for a (e.g., the current) CSI feedback report, e.g., if configured by the NW. For example, the WTRU may include an indication of the determined quantization mode (e.g., VQ or VQ+SQ) with the (e.g., reporting information indicating) CSI feedback report.

[0143] The WTRU may use the configured quantization mode for a (e.g., the current) CSI feedback report. For example, the WTRU may include (e.g., indicate) the determined quantization mode in the CSI feedback report.WTRU Determination of the VQ and SQ Parameters

[0144] The WTRU may determine the CSI based on the received CSI reference signals (CSL RS). The CSI may be represented as the channel matrix (W) or as the eigenvectors of the channel matrix. For the sake of clarity, embodiments are described herein for the case where the CSI maycorrespond to the channel matrix. Embodiments described herein are also applicable to the case where the CSI may correspond to the eigen vector.

[0145] The WTRU may compress the CSI and may determine the latent vector z corresponding to the measured channel H (e.g., using a (e.g., configured) AI / ML encoder model).

[0146] The WTRU may be configured to perform an additional quantization step to compress the latent vector z. In a hybrid vector and scalar quantization setup the quantization may be performed in two different ways, as described herein (e.g., in a first and second embodiments).

[0147] In a first embodiment, the WTRU may determine the VQ and SQ parameters as a function of a (e.g., configured) CSI feedback size Fs.

[0148] The WTRU may determine the centroid (e.g., optimal, closest codeword) for a (e.g., each) component VQ codebook of a (e.g., each) configured set of VQ codebooks. The WTRU may determine the (e.g., overall) candidate quantized vector for a (e.g., each) configured set of VQ codebooks, Cp, e.g. resulting in a plurality of candidate quantized vectors.

[0149] The WTRU may calculate the residual vector Rpassociated with the candidate quantized vector from a (e.g., each) set of VQ codebooks, where Rp= z — Cp.

[0150] Based on a fixed feedback size or bit budget for the overall feedback, Fs, and the configured metric M(-,-), the WTRU may select the combination of VQ entry and SQ bits such that M( z, Cp+ SQ(Rp)) may be maximized or minimized, depending on the metric (e.g., maximized if the metric is SGCS or minimized if the metric is NMSE), and the feedback size of the overall hybrid VQ+SQ quantized latent may remain under the (e.g., configured) CSI feedback size Fs.

[0151] An Example of the first embodiment is described herein:

[0152] In an example with z being a vector of size D=10, the WTRU may be configured withP=2 sets of VQ codebooks, and a fixed budget of 40 bits for the CSI feedback. The metric may be NMSE and may be minimized as described herein:

[0153] First VQ codebook set: [M = 1, (Nt= 1024, B = 10, log2lV1= 10)];

[0154] First VQ overhead of 10 bits. (40-10)=30 bits available in total for SQ, resulting in 3-bitSQ;

[0155] First overall Quantization error \z — ( C1+ SQ^j)) ^ = (0.1);

[0156] Second VQ codebook set: [M = 2, (Nt= 2048, B = 5, log2lV1= 11), (1V2= 512, B2= 5, log21V2= 9)];

[0157] Second VQ overhead of 20 bits. (40-20)=20 bits available in total for SQ, resulting in 2- bit SQ;

[0158] Second overall Quantization error \z — ( C2+ SQ(R2)) |2(0.15).

[0159] In this example, the first VQ codebook set may be selected (e.g., first overall quantization error being lower than second overall quantization error).

[0160] In a second embodiment, the WTRU may determine the VQ and SQ parameters as a function of a (e.g., configured) reconstruction performance threshold Ty.

[0161] The WTRU may determine the centroid (e.g., optimal, closest codeword) for a (e.g., each) component VQ codebook of a (e.g., each) configured set of VQ codebooks. The WTRU may determine the (e.g., overall) candidate quantized vector for a (e.g., each) configured set of VQ codebooks, Cp, e.g. resulting in a plurality of candidate quantized vectors.

[0162] The WTRU may calculate the residual vector Rpassociated with the candidate quantized vector from a (e.g., each) set of VQ codebooks, where Rp= z — Cp.

[0163] The WTRU may select the combination of VQ entry and SQ bits such that for the configured metric a (e.g., minimum, lower bound) performance criterion (e.g., threshold) may be met. For example, M( z, Cp+ SQ(Rp)) may be greater / lesser (depending on the metric) than Ty, (e.g., greater than Tf if SGCS is used as metric, lesser than Tf if NMSE is used as metric) and the feedback size of the (e.g., overall) hybrid VQ+SQ scheme may be minimized.

[0164] An Example of the second embodiment is described herein:

[0165] In an example with z being a vector of size D=10, the WTRU may be configured withP=2 sets of VQ codebooks. The metric be NMSE and a minimum performance threshold of Tf =0.25.

[0166] First VQ codebook set: [M = 1, (^ = 1024, B1= 10, log2lV1= 10)];

[0167] First VQ Overhead of 10 bits may achieve a performance of \z — C1|2= (0.35);

[0168] Using 20 bits for SQ may result in 2 -bit SQ per element.

[0169] First overall quantization error \z — ( C1+ SQ^i)) ^ = (0.26);

[0170] Second VQ codebook set:512, B2= 5, log2lV2= 9)];

[0171] Second VQ overhead of 20 bits may achieve a performance of \z — C2|2= (0.27);

[0172] Using 10 bits for SQ may result in 1 -bit SQ per element.

[0173] Second overall quantization error: \z — ( C2+ SQ(R2)) |2(0.24).

[0174] In this example, the second VQ codebook may be selected (e.g., being lower than the performance threshold of T = 0.25.)Fallback Procedures and Error Handling

[0175] Fallback procedures and error handing are described herein.Error Handling

[0176] The WTRU may (e.g., be configured to) monitor error performance of the hybrid quantization procedure any of continuously (e.g., at every CSI feedback report), periodically (e.g., at (e.g., every) kt / lreport), or a-periodically. The WTRU may be triggered (e.g., based on the configuration) for the activation and initiation of a fallback procedure.

[0177] Any of continuous and periodic error handling may be based on the calculation and updates of error events frequencies based on the error handling period e.g., in a case where hybrid vector quantization is activated. In one example, the error events may be associated with (e.g., only) the quantization error. In another example, the WTRU may be configured to associate the error events with the CSI reconstruction accuracy based on the metrics included in the configuration.

[0178] In an example, the error (e.g., determined by the WTRU) may be defined as the quantization error between the latent vector and the quantized hybrid output. In this example, the error may be collected and updated following different methods, such as e.g., based on any if an error event frequency method and an average error method.

[0179] In an error event frequency method, the WTRU may update (e.g., indicate) in a (e.g., each) subsequent hybrid CSI feedback report the error event frequency. An error event may occur when the current quantization error satisfies an error condition (e.g., is above a (e.g., pre-defined) quantization error threshold). The WTRU may update the error frequency according to the preconfigured error handling period.

[0180] In an average error method, e.g., depending on the metric for calculating the quantization error included in the configuration, the WTRU may calculate (e.g., update, indicate) the average error in a (e.g., each) feedback report e.g., if hybrid quantization is activated.

[0181] In another example, one or more quantization error method(s) may be combined with CSI feedback reconstruction error metrics based on the configuration.Triggers for Fallback:

[0182] The WTRU may initiate (e.g., activate) a fallback procedure based on error performance triggers (e.g., conditions). In one example, the triggers (e.g., conditions) may be based on shortterm or long-term performance dip. The WTRU may be configured by a counter that may indicate how many error events may be detected before initiating a fallback. The triggers (e.g., conditions) may be based on one or more performance indicator(s), as described herein.

[0183] In a first example, the triggers (e.g., conditions) may be based on quantization error performance: the WTRU may be configured with a quantization error threshold, e.g., the threshold may be any of a frequency and an average error. In a case where the error frequency (or average error) satisfies a first condition (e.g., is above a pre-configured threshold), then the WTRU may initiate a fallback procedure.

[0184] In a second example, the triggers (e.g., conditions) may be based on CSI reconstruction accuracy / error. The WTRU may be pre-configured with a performance threshold related to the CSI reconstruction performance. The WTRU may initiate a fallback in a case where the accuracy satisfies a second condition (e.g., is lower than an accuracy threshold), or in a case where the reconstruction error satisfies a third condition (e.g., is higher than a pre-configured threshold).

[0185] In a third example, the triggers (e.g., conditions) may be based on a combination of quantization error and CSI reconstruction error. E.g., the WTRU may determine if the quantization error is lower than the pre-configured threshold, and the WTRU may determine if the reconstruction performance does meet the criterion, e.g., if the pre-configured threshold(s) is met (e.g., if the reconstruction performance is lower than the pre-configured threshold).

[0186] In another example, the WTRU may be triggered by the overall overhead over any of a period and a number of hybrid CSI feedback reports, which may be included in the configuration.

[0187] In an example, the WTRU may be triggered to initiate a fallback procedure. For example, the WTRU may initiate a fallback procedure based on an error event having occurred.

[0188] In one example, the WTRU may fall back to SQ (e.g., uniform SQ), for example, based on a quantization error (e.g., when the trigger is the quantization error). In this example, the WTRU may determine the number of bits for SQ such that the quantization error may be smaller than a (e.g., configured) threshold. The WTRU may report (e.g., indicate) SQ (scalar quantization) as the fallback quantization mode. In an example, the WTRU may further indicate the determined number of bits for SQ.

[0189] In another example, the WTRU may fall back to non-AI / ML CSI feedback reporting, for example, based on a reconstruction error (e.g., when the trigger is reconstruction error (or a combination of any of reconstruction error and quantization error). In this example, the WTRU may report (e.g., indicate) the fallback to be non-AI / ML CSI feedback and may use the default CSI report configuration to report to the NW the measured CSI.WTRU CSI Feedback Reporting for Hybrid VQ+SQ

[0190] Methods for transmitting CSI feedback reporting by the WTRU are described herein.CSI Feedback Report Components

[0191] A WTRU may report (e.g., transmit) CSI feedback for compressed and quantized CSI measurements. The CSI feedback may be reported in one or more CSI feedback report instances. The CSI feedback report may include one or more CSI feedback components. The CSI feedback components may include information according to at least one of the following examples.

[0192] In a first example, a CSI feedback component may include (e.g., indicate) an identity of a set of VQ codebooks. The identified set of VQ codebooks may be one that may be selected by a WTRU. The identified set of VQ codebooks may be one from a plurality of configured sets of VQcodebooks. In an example, the identity may be reported as an index e.g., corresponding to a (e.g., configurable) table of sets of VQ codebooks. In another example, the identity of a selected set of VQ codebooks may include a set of parameters (e.g., for a WTRU determined or constructed set of VQ codebooks).

[0193] In a second example, a CSI feedback component may include (e.g., indicate) an identity of one or more codewords associated with one or more VQ codebook(s) of one or more set(s) of VQ codebooks. For example, a WTRU may report the identity of one codeword per VQ codebook of a set of VQ codebooks. The identity reported may be an index mapping to multiple codewords from multiple codebooks in a set of VQ codebooks. In another example, the identity reported may be an index mapping to a single codeword for a single codebook in a set of VQ codebooks. The WTRU may report multiple indices, for example, (e.g., each) associated with a codeword for a codebook in a set of VQ codebooks.

[0194] In a third example, a CSI feedback component may include (e.g., indicate) a SQ payload size. The WTRU may report the payload size of a set of SQ elements (or bits). The SQ payload size may be determined from any of an associated VQ payload size (e.g., determined from a selected set of VQ codebooks), a (e.g., maximum, upper bound) feedback payload and a quantization performance.

[0195] In a fourth example, a CSI feedback component may include (e.g., indicate) a SQ report. The WTRU may report the SQ elements or bits. For example, the SQ elements or bits may be any of associated with and determined from the measured CSI feedback or the compressed CSI feedback. In another example, the SQ elements or bits may be any of associated with and determined from the quantization error (or residue) determined from any of the measured CSI feedback, the compressed CSI feedback, and the VQ quantized CSI feedback.

[0196] In a fifth example, a CSI feedback component may indicate a quantization performance. For example, the WTRU may report the resulting quantization error from using at least one of VQ or SQ. In another example, the WTRU may report a quantization error as a function of one or more combinations of a VQ payload size, a SQ payload size, and a total feedback payload size.

[0197] In a sixth example, a CSI feedback component may include an indication of contents of a CSI feedback report. The WTRU may not report all CSI feedback report components in a CSI feedback report. The WTRU may include an indication of the set of CSI feedback report components included in a CSI feedback report.Content of a CSI Feedback Report

[0198] A WTRU may determine the one or more CSI feedback report components to include in a CSI feedback report based on any of (1) a report type, (2) a timing of the CSI feedback report, (3) a CSI feedback report resource, (4) a priority assigned to a feedback report, (5) other uplinkcontrol information (UCI) reported in the same feedback resource or in overlapping feedback resources, (6) whether UCI multiplexing or dropping may be configured (e.g., or used), (7) a change in a value of a CSI feedback report component from a previous CSI feedback report, and (8) an available CSI feedback report (e.g., maximum, upper bound) payload.

[0199] In a first example, the WTRU may determine the one or more CSI feedback report components to include in a CSI feedback report based on the report type (e.g., any of periodic, aperiodic, and semi-persistent). For example, the WTRU may report a subset of CSI feedback report components in periodic reporting. For example, the WTRU may report (e.g., all) CSI feedback report components in aperiodic reporting.

[0200] In a second example, the WTRU may determine the one or more CSI feedback report components to include in a CSI feedback report based on the timing of the CSI feedback report. For example, the WTRU may be configured with time instances for one or more CSI feedback report components. The WTRU may determine the CSI feedback report component to include in a CSI feedback report based on the timing of the CSI feedback report.

[0201] In a third example, the WTRU may determine the one or more CSI feedback report components to include in a CSI feedback report based on the CSI feedback report resource. For example, the WTRU may determine the CSI feedback report components to include in a CSI feedback report based on at least one of (1) any of a time, a frequency, a spatial state, quasi co location (QCL) state, a transmission configuration indicator (TCI) state of the feedback resource, (2) a physical uplink control channel (PUCCH) format type, and (3) whether the CSI feedback report may be transmitted on PUCCH or on physical uplink shared channel (PUSCH).

[0202] In a fourth example, the WTRU may determine the one or more CSI feedback report components to include in a CSI feedback report based on a priority assigned to a feedback report.

[0203] In a fifth example, the WTRU may determine the one or more CSI feedback report components to include in a CSI feedback report based on other UCI reported in any of the same feedback resource and in overlapping feedback resources.

[0204] In a sixth example, the WTRU may determine the one or more CSI feedback report components to include in a CSI feedback report based on whether UCI multiplexing or dropping may be any of configured and used.

[0205] In a seventh example, the WTRU may determine the one or more CSI feedback report components to include in a CSI feedback report based on a change in a value of a CSI feedback report component from a previous CSI feedback report. For example, the WTRU may determine to transmit a (e.g., new) CSI feedback report component if it includes at least one value that changed (or changed more than a (e.g., threshold) value) from a previously reported value for the same CSI feedback report component. For example, the WTRU may determine to transmit a (e.g.,new) identity of set of VQ codebooks if a (e.g., newly) selected set of VQ codebooks is different from a previously reported identity of set of VQ codebooks. In another example, a WTRU may determine to report a first CSI feedback report component if the value of a second CSI feedback report component has changed more than a (e.g., threshold) value. For example, the WTRU may report a (e.g., new) SQ payload size if the selected set of VQ codebooks has changed.

[0206] In an eighth example, the WTRU may determine the one or more CSI feedback report components to include in a CSI feedback report based on an available CSI feedback report (e.g., maximum, upper bound) payload. For example, a WTRU may (e.g., always) report a first set of CSI feedback report components. The WTRU may determine whether to include a second set of CSI feedback report components based on the remaining CSI feedback report budget.

[0207] In an example, a WTRU may determine the value of a CSI feedback component as a function of the value of another CSI feedback component. For example, the index of a VQ codeword may depend on the identity of a set of VQ codebooks. In another example, the SQ report may depend on any of the SQ payload size, the total payload size, the VQ codeword and the set of VQ codebooks. In some examples, a CSI feedback report may include the value of a second CSI feedback component that may depend on the value of a first CSI feedback component, where the value of the first CSI feedback component may not be included in the CSI feedback report. In such a case, the WTRU may be configured or may determine (and e.g., indicate) an association of CSI feedback reports indicating the timing or resources of a first CSI feedback report including a first CSI feedback component and the timing or resources of a second CSI feedback report including the second CSI feedback component.WTRU Determined and Indicated CSI Feedback Reporting Configuration]

[0208] A WTRU may determine the parameters for CSI reporting of one or more CSI feedback report components. The WTRU may indicate (e.g., transmit information indicating) to the gNB, any of the reporting periodicity and a payload (e.g., size, format) for one or more CSI feedback report components.

[0209] A WTRU may determine that a current configuration may not meet a (e.g., configured) quality or performance (e.g., quantization performance) criterion. For example, a WTRU may be configured with a first reporting format and may determine that a quality metric of the first reporting format may not meet a condition (e.g., threshold). The WTRU may determine that a quality metric of a second reporting format may meet the condition (e.g., threshold). The WTRU may indicate (e.g., transmit information indicating) to the gNB that the first reporting format may not meet the (e.g., feedback quality) criterion, or the feedback quality metric value (e.g., the feedback quality measurement of the first reporting format may not meet the feedback qualitycriterion). The WTRU may indicate to the gNB the identity of the WTRU-determined second reporting format.

[0210] Examples of quality metric may include any of (1) a quantization error (for a single reporting instance or averaged over multiple reporting instances), (2) a CSI feedback payload (e.g., size), a reconstruction performance, a compression / decompression error. The WTRU may be configured with one or more criteria (e.g., thresholds) for at least one of the quality metrics.

[0211] Examples of reporting formats may include any of (1) a plurality of sets of VQ codebooks, (2) a CSI feedback report payload size, (3) any of (i) VQ only, (ii) SQ only, and (iii) VQ and SQ reporting, (4) uniform or non-uniform quantization, and (5) quantization range or granularity.

[0212] In the example of a reporting format including a CSI feedback report payload size, the CSI feedback report payload size may include any of a payload restricted to VQ feedback, payload restricted to SQ feedback, and payload restricted to total feedback.Example of Hybrid Vector and Scalar Quantization Method

[0213] A WTRU may be capable of performing hybrid vector and scalar quantization (e.g., for AI / ML based CSI compression). The WTRU may be configured with (e.g., receive first configuration information indicating) one or more sets of VQ codebooks, e.g., P sets of VQ codebooks.

[0214] The WTRU may receive from the NW (e.g., second configuration information indicating) the configuration for the metric to evaluate the CSI reconstruction performance, and the corresponding reconstruction performance criteria (e.g., thresholds). The metric may be any of a SGCS, a NMSE, a distance, a normalized distance and a quantization error.

[0215] The WTRU may determine the CSI based on the received CSI-RS. The CSI may be represented as the channel matrix (H) or the eigenvectors of the channel matrix. The WTRU may compress the CSI and may determine the latent vector z corresponding to the measured channel H (e.g., using a configured AI / ML encoder model).

[0216] The WTRU may perform vector quantization of the latent vector z for a (e.g., each) configured set of VQ codebooks (e.g., for sets VQ codebooks meeting the (e.g., configured) CSI feedback size). In an example, the WTRU may determine the centroid (e.g., optimal, closest codeword) for a (e.g., each) component VQ codebook of a (e.g., each) configured set of VQ codebooks (e.g., satisfying the CSI feedback size criterion). The WTRU may determine the overall candidate quantized vector (e.g., based on the determined centroids) for a (e.g., each) configured set of VQ codebooks, Cp. The WTRU may calculate the residual vector Rpassociated with the candidate quantized vector from a (e.g., each) set of VQ codebooks, where e.g., Rp= z — Cp.

[0217] In a hybrid quantization mode, the WTRU may select the set of VQ codebooks and the number of bits for SQ as a function of a (e.g., configured) CSI feedback size and / or a (e.g., configured) reconstruction performance criterion (e.g., threshold).

[0218] In an example, for a fixed CSI feedback report size, the WTRU may select the VQ set and the number of bits for SQ to minimize the quantization error between the latent vector z and the hybrid quantized output, Cp+ SQ(Rpwhile keeping the total feedback size below the configured threshold.

[0219] In an example, for a configured quantization error / reconstruction performance criterion (e.g., threshold), the WTRU may select the set of VQ codebooks and the SQ bits to minimize the total feedback size while keeping the quantization error below the configured threshold.

[0220] The WTRU may report one or more of the selected set of VQ codebooks, the number of bits for SQ and the quantized compressed CSI.

[0221] In an example, a first part of the report may indicate any of the (e.g., index of the) selected set of VQ codebooks, and the indices of the clusters / codewords of a (e.g., each) component VQ codebook of the selected set of VQ codebooks.

[0222] In an example, a second part of the report may indicate any of the number of bits used for scalar quantization of the residual vector, and the quantized residual vector.

[0223] In an example, the first part may (e.g., always) be reported and the second part may (e.g., only) be reported if additional bit budget for reporting is available.

[0224] In another example, the first part may (e.g., only) be reported when a codebook index changes and the second part corresponding to the residue may be reported in (e.g., all) feedback reports.

[0225] FIG. 7 is a diagram illustrating an example method 700 for hybrid vector and scalar quantization of CSI feedback in a WTRU.

[0226] As shown at 70, the WTRU may receive configuration information indicating a plurality (P) of sets of VQ codebooks and a reconstruction performance criterion (e.g., threshold).

[0227] As shown at 72, the WTRU may determine a CSI. The WTRU may perform CSI compression to determine a latent vector z.

[0228] As shown at 74, the WTRU may perform vector quantization for a (e.g., each) configured set of VQ codebooks. The WTRU may determine a candidate quantized vector for a (e.g., each) set of VQ codebooks (e.g., satisfying a criterion).

[0229] As shown at 76, the WTRU may determine a set of VQ codebooks and a number of bits for scalar quantization as a function of (e.g., based on) any of a (e.g., configured) CSI feedback size and a reconstruction performance criterion (e.g., threshold).

[0230] As shown at 78, the WTRU may report any of the selected set of VQ codebooks, the number of bits for SQ, and the quantized compressed CSI. The quantized compressed CSI may correspond to the result of the quantization of the latent vector, performed on the selected set of VQ codebooks.

[0231] FIG. 8 is a diagram illustrating an example method 800 for hybrid vector and scalar quantization of CSI feedback in a WTRU. The method 800 may be implemented in a WTRU. As shown at 810, the WTRU may receive one or more reference signals. As shown at 820, the WTRU may determine CSI based on the one or more reference signals. As shown at 830, the WTRU may determine a (e.g., latent) vector based on a compression of the CSI. As shown at 840, the WTRU may perform vector quantization of the (e.g., latent) vector for a plurality of sets of vector quantization codebooks, e.g., resulting in a plurality of quantized compressed CSI candidates, where a (e.g., each) quantized compressed CSI candidate may be associated with one set of vector quantization codebooks. As shown at 850, the WTRU may select (1) a set of vector quantization codebooks from the plurality of sets of vector quantization codebooks and (2) a number of bits for scalar quantization based on any of a CSI feedback size and a reconstruction performance criterion. As shown at 860, the WTRU may transmit reporting information indicating the selected set of vector quantization codebooks of the plurality of quantized compressed CSI candidates and a quantized compressed CSI associated with (e.g., quantized according to) the set of vector quantization codebooks.

[0232] In various embodiments, the reporting information may indicate the number of bits for scalar quantization.

[0233] In various embodiments, the reporting information may indicate a quantized residual vector.

[0234] In various embodiments, the reporting information may indicate a hybrid vector and scalar quantization mode of operation.

[0235] In various embodiments, the reporting information may indicate an index of the selected set of vector quantization codebooks in the plurality of sets of vector quantization codebooks.

[0236] In various embodiments, the reporting information may indicate any of (i) a quantized residual vector, (ii) a hybrid vector and scalar quantization mode of operation, and (iii) an index of the selected set of vector quantization codebooks in the plurality of sets of vector quantization codebooks.

[0237] In various embodiments, perform vector quantization of the latent vector for the set of vector quantization codebooks may comprise select, for the latent vector, a set of entries from the set of vector quantization codebooks.

[0238] In various embodiments, the quantized compressed CSI may be indicated by indices of the entries selected from the set of vector quantization codebooks.

[0239] In various embodiments, the set of vector quantization codebooks and the number of bits for scalar quantization may be selected based on a size of the reporting information being below the CSI feedback size.

[0240] In various embodiments, the set of vector quantization codebooks and the number of bits for scalar quantization may be selected based on a quantization error of the quantized compressed CSI satisfying the reconstruction performance criterion.

[0241] In various embodiments, the quantization error of the quantized compressed CSI may satisfy the reconstruction performance criterion in a case where the quantization error is below a reconstruction performance threshold.

[0242] In various embodiments, the WTRU may receive first configuration information indicating the plurality of sets of vector quantization codebooks.

[0243] In various embodiments, the first configuration information may indicate the CSI feedback size.

[0244] In various embodiments, the first configuration information may indicate any of (1) a vector quantization bit budget allocated for reporting vector quantization information and (2) a scalar quantization bit budget allocated for reporting residual error information using scalar quantization.

[0245] In various embodiments, the WTRU may receive second configuration information indicating the reconstruction performance criterion.

[0246] In various embodiments, the reconstruction performance criterion may be associated with a performance on a hybrid vector quantization and scalar quantization operation.

[0247] In various embodiments, the second configuration information may indicate a first reconstruction performance criterion to be used for controlling a vector quantization error.

[0248] In various embodiments, the second configuration information may indicate a second reconstruction performance criterion to be used for controlling a scalar quantization error associated with a residual error.

[0249] In various embodiments, the WTRU may determine a quantization error between the quantized compressed CSI and the latent vector.

[0250] In various embodiments, the WTRU may determine that an error event may have occurred based on the quantization error satisfying an error condition.

[0251] In various embodiments, the quantization error may satisfy the error condition if the quantization error is above a threshold.

[0252] In various embodiments, the WTRU may initiate a fallback procedure based on the error event having occurred.

[0253] FIG. 9 is a diagram illustrating an example method 900 for hybrid vector and scalar quantization of CSI feedback in a network element. The method 900 may be implemented in a network element, such as, for example, a base station. As shown at 910, the network element may transmit one or more reference signals to a WTRU. As shown at 920, the network element may receive from the WTRU, reporting information indicating a set of vector quantization codebooks of a plurality of sets of vector quantization codebooks, a quantized compressed channel state information (CSI) associated with the set of vector quantization codebooks and a number of bits used for scalar quantization. As shown at 930, the network element may dequantize the quantized compressed CSI based on the indicated set of vector quantization codebooks and the indicated number of bits used for scalar quantization. As shown at 940, the network element may determine a CSI associated with the WTRU based on the dequantized compressed CSI.

[0254] In various embodiments, the reporting information may indicate a quantized residual vector.

[0255] In various embodiments, the reporting information may indicate a hybrid vector and scalar quantization mode of operation.

[0256] In various embodiments, the reporting information may indicate an index of the set of vector quantization codebooks in the plurality of sets of vector quantization codebooks.

[0257] In various embodiments, the reporting information may indicate any of (i) a quantized residual vector, (ii) a hybrid vector and scalar quantization mode of operation, and (iii) an index of the set of vector quantization codebooks in the plurality of sets of vector quantization codebooks.

[0258] In various embodiments, the quantized compressed CSI may be indicated by indices of entries selected from the set of vector quantization codebooks.

[0259] In various embodiments, the network element may send first configuration information indicating the plurality of sets of vector quantization codebooks.

[0260] In various embodiments, the first configuration information may indicate the CSI feedback size.

[0261] In various embodiments, the first configuration information may indicate any of (1) a vector quantization bit budget allocated for reporting vector quantization information and (2) a scalar quantization bit budget allocated for reporting residual error information using scalar quantization.

[0262] In various embodiments, the network element may send second configuration information indicating the reconstruction performance criterion.

[0263] In various embodiments, the reconstruction performance criterion may be associated with a performance on a hybrid vector quantization and scalar quantization operation.

[0264] In various embodiments, the second configuration information may indicate a first reconstruction performance criterion to be used for controlling a vector quantization error.

[0265] In various embodiments, the second configuration information may indicate a second reconstruction performance criterion to be used for controlling a scalar quantization error associated with a residual error.

[0266]

[0267] While not explicitly described, embodiments described herein may be employed in any combination or sub-combination. For example, the present principles are not limited to the described variants, and any arrangement of variants and embodiments can be used.

[0268] Besides, any characteristic, variant or embodiment described for a method is compatible with an apparatus device comprising means for processing the disclosed method, with a device comprising circuitry, including any of a transceiver, a processor and memory, the circuitry being configured to process the disclosed method, with a computer program product comprising program code instructions and with a non-transitory computer-readable storage medium storing program instructions. Any characteristic, variant or embodiment described for a method, or an apparatus device directed to a WTRU is compatible with a method or an apparatus directed to a network (e.g., infrastructure) element.

[0269] Although features and elements are provided above in particular combinations, one of ordinary skill in the art will appreciate that each feature or element can be used alone or in any combination with the other features and elements. The present disclosure is not to be limited in terms of the particular embodiments described in this application, which are intended as illustrations of various aspects. Many modifications and variations may be made without departing from its spirit and scope, as will be apparent to those skilled in the art. No element, act, or instruction used in the description of the present application should be construed as critical or essential to the invention unless explicitly provided as such. Functionally equivalent methods and apparatuses within the scope of the disclosure, in addition to those enumerated herein, will be apparent to those skilled in the art from the foregoing descriptions. Such modifications and variations are intended to fall within the scope of the appended claims. The present disclosure is to be limited only by the terms of the appended claims, along with the full scope of equivalents to which such claims are entitled. It is to be understood that this disclosure is not limited to particular methods or systems.

[0270] The foregoing embodiments are discussed, for simplicity, with regard to the terminology and structure of infrared capable devices, i.e., infrared emitters and receivers. However, the embodiments discussed are not limited to these systems but may be applied to other systems that use other forms of electromagnetic waves or non-electromagnetic waves such as acoustic waves.

[0271] It is also to be understood that the terminology used herein is for the purpose of describing particular embodiments only, and is not intended to be limiting. As used herein, the term "video" or the term "imagery" may mean any of a snapshot, single image and / or multiple images displayed over a time basis. As another example, when referred to herein, the terms "user equipment" and its abbreviation "UE", the term "remote" and / or the terms "head mounted display" or its abbreviation "HMD" may mean or include (i) a wireless transmit and / or receive unit (WTRU); (ii) any of a number of embodiments of a WTRU; (iii) a wireless-capable and / or wired-capable (e.g., tetherable) device configured with, inter alia, some or all structures and functionality of a WTRU; (iii) a wireless-capable and / or wired-capable device configured with less than all structures and functionality of a WTRU; or (iv) the like. Details of an example WTRU, which may be representative of any WTRU recited herein, are provided herein with respect to FIGs. 1 A-1D. As another example, various disclosed embodiments herein supra and infra are described as utilizing a head mounted display. Those skilled in the art will recognize that a device other than the head mounted display may be utilized and some or all of the disclosure and various disclosed embodiments can be modified accordingly without undue experimentation. Examples of such other device may include a drone or other device configured to stream information for providing the adapted reality experience.

[0272] In addition, the methods provided herein may be implemented in a computer program, software, or firmware incorporated in a computer-readable medium for execution by a computer or processor. Examples of computer-readable media include electronic signals (transmitted over wired or wireless connections) and computer-readable storage media. Examples of computer- readable storage media include, but are not limited to, a read only memory (ROM), a random access memory (RAM), a register, cache memory, semiconductor memory devices, magnetic media such as internal hard disks and removable disks, magneto-optical media, and optical media such as CD-ROM disks, and digital versatile disks (DVDs). A processor in association with software may be used to implement a radio frequency transceiver for use in a WTRU, UE, terminal, base station, RNC, or any host computer.

[0273] Variations of the method, apparatus and system provided above are possible without departing from the scope of the invention. In view of the wide variety of embodiments that can be applied, it should be understood that the illustrated embodiments are examples only, and should not be taken as limiting the scope of the following claims. For instance, the embodiments providedherein include handheld devices, which may include or be utilized with any appropriate voltage source, such as a battery and the like, providing any appropriate voltage.

[0274] Moreover, in the embodiments provided above, processing platforms, computing systems, controllers, and other devices that include processors are noted. These devices may include at least one Central Processing Unit ("CPU") and memory. In accordance with the practices of persons skilled in the art of computer programming, reference to acts and symbolic representations of operations or instructions may be performed by the various CPUs and memories. Such acts and operations or instructions may be referred to as being "executed," "computer executed" or "CPU executed."

[0275] One of ordinary skill in the art will appreciate that the acts and symbolically represented operations or instructions include the manipulation of electrical signals by the CPU. An electrical system represents data bits that can cause a resulting transformation or reduction of the electrical signals and the maintenance of data bits at memory locations in a memory system to thereby reconfigure or otherwise alter the CPU's operation, as well as other processing of signals. The memory locations where data bits are maintained are physical locations that have particular electrical, magnetic, optical, or organic properties corresponding to or representative of the data bits. It should be understood that the embodiments are not limited to the above-mentioned platforms or CPUs and that other platforms and CPUs may support the provided methods.

[0276] The data bits may also be maintained on a computer readable medium including magnetic disks, optical disks, and any other volatile (e.g., Random Access Memory (RAM)) or non-volatile (e.g., Read-Only Memory (ROM)) mass storage system readable by the CPU. The computer readable medium may include cooperating or interconnected computer readable medium, which exist exclusively on the processing system or are distributed among multiple interconnected processing systems that may be local or remote to the processing system. It should be understood that the embodiments are not limited to the above-mentioned memories and that other platforms and memories may support the provided methods.

[0277] In an illustrative embodiment, any of the operations, processes, etc. described herein may be implemented as computer-readable instructions stored on a computer-readable medium. The computer-readable instructions may be executed by a processor of a mobile unit, a network element, and / or any other computing device.

[0278] There is little distinction left between hardware and software implementations of aspects of systems. The use of hardware or software is generally (but not always, in that in certain contexts the choice between hardware and software may become significant) a design choice representing cost versus efficiency tradeoffs. There may be various vehicles by which processes and / or systems and / or other technologies described herein may be effected (e.g., hardware, software, and / orfirmware), and the preferred vehicle may vary with the context in which the processes and / or systems and / or other technologies are deployed. For example, if an implementer determines that speed and accuracy are paramount, the implementer may opt for a mainly hardware and / or firmware vehicle. If flexibility is paramount, the implementer may opt for a mainly software implementation. Alternatively, the implementer may opt for some combination of hardware, software, and / or firmware.

[0279] The foregoing detailed description has set forth various embodiments of the devices and / or processes via the use of block diagrams, flowcharts, and / or examples. Insofar as such block diagrams, flowcharts, and / or examples include one or more functions and / or operations, it will be understood by those within the art that each function and / or operation within such block diagrams, flowcharts, or examples may be implemented, individually and / or collectively, by a wide range of hardware, software, firmware, or virtually any combination thereof. In an embodiment, several portions of the subject matter described herein may be implemented via Application Specific Integrated Circuits (ASICs), Field Programmable Gate Arrays (FPGAs), digital signal processors (DSPs), and / or other integrated formats. However, those skilled in the art will recognize that some aspects of the embodiments disclosed herein, in whole or in part, may be equivalently implemented in integrated circuits, as one or more computer programs running on one or more computers (e.g., as one or more programs running on one or more computer systems), as one or more programs running on one or more processors (e.g., as one or more programs running on one or more microprocessors), as firmware, or as virtually any combination thereof, and that designing the circuitry and / or writing the code for the software and or firmware would be well within the skill of one of skill in the art in light of this disclosure. In addition, those skilled in the art will appreciate that the mechanisms of the subject matter described herein may be distributed as a program product in a variety of forms, and that an illustrative embodiment of the subject matter described herein applies regardless of the particular type of signal bearing medium used to actually carry out the distribution. Examples of a signal bearing medium include, but are not limited to, the following: a recordable type medium such as a floppy disk, a hard disk drive, a CD, a DVD, a digital tape, a computer memory, etc., and a transmission type medium such as a digital and / or an analog communication medium (e.g., a fiber optic cable, a waveguide, a wired communications link, a wireless communication link, etc.).

[0280] Those skilled in the art will recognize that it is common within the art to describe devices and / or processes in the fashion set forth herein, and thereafter use engineering practices to integrate such described devices and / or processes into data processing systems. That is, at least a portion of the devices and / or processes described herein may be integrated into a data processing system via a reasonable amount of experimentation. Those having skill in the art will recognize that a typicaldata processing system may generally include one or more of a system unit housing, a video display device, a memory such as volatile and non-volatile memory, processors such as microprocessors and digital signal processors, computational entities such as operating systems, drivers, graphical user interfaces, and applications programs, one or more interaction devices, such as a touch pad or screen, and / or control systems including feedback loops and control motors (e.g., feedback for sensing position and / or velocity, control motors for moving and / or adjusting components and / or quantities). A typical data processing system may be implemented utilizing any suitable commercially available components, such as those typically found in data computing / communication and / or network computing / communication systems.

[0281] The herein described subject matter sometimes illustrates different components included within, or connected with, different other components. It is to be understood that such depicted architectures are merely examples, and that in fact many other architectures may be implemented which achieve the same functionality. In a conceptual sense, any arrangement of components to achieve the same functionality is effectively "associated" such that the desired functionality may be achieved. Hence, any two components herein combined to achieve a particular functionality may be seen as "associated with" each other such that the desired functionality is achieved, irrespective of architectures or intermedial components. Likewise, any two components so associated may also be viewed as being "operably connected", or "operably coupled", to each other to achieve the desired functionality, and any two components capable of being so associated may also be viewed as being "operably couplable" to each other to achieve the desired functionality. Specific examples of operably couplable include but are not limited to physically mateable and / or physically interacting components and / or wirelessly interactable and / or wirelessly interacting components and / or logically interacting and / or logically interactable components.

[0282] With respect to the use of substantially any plural and / or singular terms herein, those having skill in the art can translate from the plural to the singular and / or from the singular to the plural as is appropriate to the context and / or application. The various singular / plural permutations may be expressly set forth herein for sake of clarity.

[0283] It will be understood by those within the art that, in general, terms used herein, and especially in the appended claims (e.g., bodies of the appended claims) are generally intended as "open" terms (e.g., the term "including" should be interpreted as "including but not limited to," the term "having" should be interpreted as "having at least," the term "includes" should be interpreted as "includes but is not limited to," etc.). It will be further understood by those within the art that if a specific number of an introduced claim recitation is intended, such an intent will be explicitly recited in the claim, and in the absence of such recitation no such intent is present. For example, where only one item is intended, the term "single" or similar language may be used. As an aid tounderstanding, the following appended claims and / or the descriptions herein may include usage of the introductory phrases "at least one" and "one or more" to introduce claim recitations. However, the use of such phrases should not be construed to imply that the introduction of a claim recitation by the indefinite articles "a" or "an" limits any particular claim including such introduced claim recitation to embodiments including only one such recitation, even when the same claim includes the introductory phrases "one or more" or "at least one" and indefinite articles such as "a" or "an" (e.g., "a" and / or "an" should be interpreted to mean "at least one" or "one or more"). The same holds true for the use of definite articles used to introduce claim recitations. In addition, even if a specific number of an introduced claim recitation is explicitly recited, those skilled in the art will recognize that such recitation should be interpreted to mean at least the recited number (e.g., the bare recitation of "two recitations," without other modifiers, means at least two recitations, or two or more recitations). Furthermore, in those instances where a convention analogous to "at least one of A, B, and C, etc." is used, in general such a construction is intended in the sense one having skill in the art would understand the convention (e.g., "a system having at least one of A, B, and C" would include but not be limited to systems that have A alone, B alone, C alone, A and B together, A and C together, B and C together, and / or A, B, and C together, etc.). In those instances where a convention analogous to "at least one of A, B, or C, etc." is used, in general such a construction is intended in the sense one having skill in the art would understand the convention (e.g., "a system having at least one of A, B, or C" would include but not be limited to systems that have A alone, B alone, C alone, A and B together, A and C together, B and C together, and / or A, B, and C together, etc.). It will be further understood by those within the art that virtually any disjunctive word and / or phrase presenting two or more alternative terms, whether in the description, claims, or drawings, should be understood to contemplate the possibilities of including one of the terms, either of the terms, or both terms. For example, the phrase "A or B" will be understood to include the possibilities of "A" or "B" or "A and B." Further, the terms "any of' followed by a listing of a plurality of items and / or a plurality of categories of items, as used herein, are intended to include "any of," "any combination of," "any multiple of," and / or "any combination of multiples of the items and / or the categories of items, individually or in conjunction with other items and / or other categories of items. Moreover, as used herein, the term "set" is intended to include any number of items, including zero. Additionally, as used herein, the term "number" is intended to include any number, including zero. And the term "multiple", as used herein, is intended to be synonymous with "a plurality".

[0284] In addition, where features or aspects of the disclosure are described in terms of Markush groups, those skilled in the art will recognize that the disclosure is also thereby described in terms of any individual member or subgroup of members of the Markush group.

[0285] As will be understood by one skilled in the art, for any and all purposes, such as in terms of providing a written description, all ranges disclosed herein also encompass any and all possible subranges and combinations of subranges thereof. Any listed range can be easily recognized as sufficiently describing and enabling the same range being broken down into at least equal halves, thirds, quarters, fifths, tenths, etc. As a non-limiting example, each range discussed herein may be readily broken down into a lower third, middle third and upper third, etc. As will also be understood by one skilled in the art all language such as "up to," "at least," "greater than," "less than," and the like includes the number recited and refers to ranges which can be subsequently broken down into subranges as discussed above. Finally, as will be understood by one skilled in the art, a range includes each individual member. Thus, for example, a group having 1-3 cells refers to groups having 1, 2, or 3 cells. Similarly, a group having 1-5 cells refers to groups having 1, 2, 3, 4, or 5 cells, and so forth.

[0286] Moreover, the claims should not be read as limited to the provided order or elements unless stated to that effect. In addition, use of the terms "means for" in any claim is intended to invoke 35 U.S.C. §112, 6 or means-plus-function claim format, and any claim without the terms "means for" is not so intended.

Claims

CLAIMSWhat is claimed is:

1. A wireless transmit / receive unit (WTRU) comprising circuitry, including any of a transceiver, a processor, and memory, configured to: receive one or more reference signals; determine channel state information (CSI) based on the one or more reference signals; determine a latent vector based on a compression of the CSI; perform vector quantization of the latent vector for a plurality of sets of vector quantization codebooks resulting in a plurality of quantized compressed CSI candidates, each quantized compressed CSI candidate being associated with one set of vector quantization codebooks; select (1) a set of vector quantization codebooks from the plurality of sets of vector quantization codebooks and (2) a number of bits for scalar quantization based on any of a CSI feedback size and a reconstruction performance criterion; and transmit reporting information indicating the selected set of vector quantization codebooks and a quantized compressed CSI of the plurality of quantized compressed CSI candidates associated with the selected set of vector quantization codebooks.

2. The WTRU of claim 1, wherein the reporting information further indicates the number of bits for scalar quantization.

3. The WTRU of any of claims 1 to 2, wherein the reporting information further indicates any of (i) a quantized residual vector, (ii) a hybrid vector and scalar quantization mode of operation, and (iii) an index of the selected set of vector quantization codebooks in the plurality of sets of vector quantization codebooks.

4. The WTRU of any of claims 1 to 3, wherein the WTRU being configured to perform vector quantization of the latent vector for the set of vector quantization codebooks comprises the WTRU being configured to select, for the latent vector, a set of entries from the set of vector quantization codebooks.

5. The WTRU of claim 4, wherein the quantized compressed CSI is indicated by indices of the entries selected from the set of vector quantization codebooks.

6. The WTRU of any of claims 1 to 5, wherein the set of vector quantization codebooks and the number of bits for scalar quantization are selected based on a size of the reporting information being below the CSI feedback size.

7. The WTRU of any of claims 1 to 6, wherein the set of vector quantization codebooks and the number of bits for scalar quantization are selected based on a quantization error of the quantized compressed CSI satisfying the reconstruction performance criterion.

8. The WTRU of claim 7, wherein the quantization error of the quantized compressed CSI satisfies the reconstruction performance criterion in a case where the quantization error is below a reconstruction performance threshold.

9. The WTRU of any of claims 1 to 8, configured to receive first configuration information indicating the plurality of sets of vector quantization codebooks.

10. The WTRU of claim 9, wherein the first configuration information indicates the CSI feedback size.

11. The WTRU of any of claims 9 to 10, wherein the first configuration information indicates any of (1) a vector quantization bit budget allocated for reporting vector quantization information and (2) a scalar quantization bit budget allocated for reporting residual error information using scalar quantization.

12. The WTRU of any of claims 1 to 11, configured to receive second configuration information indicating the reconstruction performance criterion.

13. The WTRU of any of claims 1 to 12, wherein the reconstruction performance criterion is associated with a performance on a hybrid vector quantization and scalar quantization operation.

14. The WTRU of any of claims 12 to 13, wherein the second configuration information indicates a first reconstruction performance criterion to be used for controlling a vector quantization error.

15. The WTRU of any of claims 12 to 14, wherein the second configuration information indicates a second reconstruction performance criterion to be used for controlling a scalar quantization error associated with a residual error.

16. The WTRU of any of claims 1 to 15, wherein the WTRU is configured to determine a quantization error between the quantized compressed CSI and the latent vector.

17. The WTRU of claim 16, wherein the WTRU is configured to determine that an error event has occurred based on the quantization error satisfying an error condition.

18. The WTRU of claim 17, wherein the quantization error satisfies the error condition if the quantization error is above a threshold.

19. The WTRU of any of claims 17 to 18, wherein the WTRU is configured to initiate a fallback procedure based on the error event having occurred.

20. A method implemented in a wireless transmit / receive unit (WTRU), the method comprising: receiving one or more reference signals; determining channel state information (CSI) based on the one or more reference signals; determining a latent vector based on a compression of the CSI; performing vector quantization of the latent vector for a plurality of sets of vector quantization codebooks resulting in a plurality of quantized compressed CSI candidates, each quantized compressed CSI candidate being associated with one set of vector quantization codebooks; selecting (1) a set of vector quantization codebooks from the plurality of sets of vector quantization codebooks and (2) a number of bits for scalar quantization based on any of a CSI feedback size and a reconstruction performance criterion; and transmitting reporting information indicating the set of vector quantization codebooks and a quantized compressed CSI of the plurality of quantized compressed CSI candidates associated with the set of vector quantization codebooks.

21. A method implemented in a network element, the method comprising: transmitting one or more reference signals to a wireless transmit / receive unit (WTRU); receiving from the WTRU, reporting information indicating a set of vector quantization codebooks of a plurality of sets of vector quantization codebooks, a quantized compressed channel state information (CSI) associated with the set of vector quantization codebooks and a number of bits used for scalar quantization; dequantizing the quantized compressed CSI based on the set of vector quantization codebooks and the number of bits used for scalar quantization; and determining a CSI associated with the WTRU based on the dequantized compressed CSI.

22. A network element comprising circuitry, including any of a transceiver, a processor, and memory, configured to: transmit one or more reference signals to a wireless transmit / receive unit (WTRU); receive from the WTRU, reporting information indicating a set of vector quantization codebooks of a plurality of sets of vector quantization codebooks, a quantized compressed channel state information (CSI) associated with the set of vector quantization codebooks and a number of bits used for scalar quantization; dequantize the quantized compressed CSI based on the set of vector quantization codebooks and the number of bits used for scalar quantization; anddetermine a CSI associated with the WTRU based on the dequantized compressed CSI.

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