Method and apparatus for reference signal overhead reduction in wireless communication system

Abstract

A process, method, architecture, apparatus, system, apparatus and computer program product are directed to reducing signaling overhead in conjunction with processing of reference signals. In an embodiment, an apparatus may be configured to: receive configuration information including channel state information (CSI) spatial prediction parameters from a network node; receiving a first plurality of reference signals transmitted from a plurality of antenna ports of the network node; estimating a first CSI measurement based on the plurality of received reference signals; and determining a first subset of antenna ports of a plurality of antenna ports of the network node and one or more parameters associated with the first subset of antenna ports based on the first CSI measurement and the CSI spatial prediction parameters, wherein the first subset is smaller than the plurality of antenna ports.

Description

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This patent application claims the benefit of U.S. Provisional Patent Application No. 63 / 335,038, filed on April 26, 2022, which is incorporated herein by reference. Technical Field

[0003] The present disclosure generally relates to the field of wireless communication networks. For example, one or more embodiments disclosed herein relate to methods, devices, systems and / or processes for reducing signaling overhead in conjunction with reference signals, particularly but not exclusively in 3GPP cellular network systems. Background Art

[0004] For downlink scheduling and link adaptation purposes for single-user (SU) and multi-user (MU)-MIMO (multiple-input multiple-output), accurate knowledge of the channel can be used. This can be achieved using the downlink (DL) channel state information (CSI) reference signal (CSI-RS) to achieve channel estimation at the UE and by feeding back the estimated CSI (e.g., implicit CSI: channel quality indicator (CQI), precoding matrix indicator (PMI), rank indicator (RI), layer indicator (LI)) in the UE CSI report. However, since 5G NR supports up to 32 antenna ports, there is a large overhead associated with the DL CSI-RS and the corresponding uplink (UL) CSI reports. This overhead is expected to increase with the increase in system bandwidth and number of antennas in B5G (beyond 5G) massive MIMO systems. BRIEF DESCRIPTION OF THE DRAWINGS

[0005] A more detailed understanding may be obtained from the following detailed description given by way of example in conjunction with the accompanying drawings. As with the detailed description, each of the figures in such drawings is exemplary. Therefore, each of the figures and detailed description should not be considered limiting, and other equally effective examples are possible and possible. In addition, the same reference numerals ("reference numerals") in the various figures ("Figures") indicate the same elements, and wherein:

[0006] Figure 1A is a system diagram illustrating an example communication system in which one or more disclosed embodiments may be implemented;

[0007] Figure 1B is a diagram showing that according to an embodiment, Figure 1A A system diagram of an example wireless transmit / receive unit (WTRU) for use within a communication system is shown;

[0008] Figure 1C is a diagram showing that according to an embodiment, Figure 1AA system diagram of an example radio access network (RAN) and an example core network (CN) used within the illustrated communication system;

[0009] Figure 1D is a diagram showing that according to an embodiment, Figure 1A A system diagram of yet another example RAN and yet another example CN used within the communication system shown;

[0010] Figure 2 is a diagram showing an example of configuration of CSI report settings, resource settings, and links;

[0011] Figure 3 is a diagram illustrating codebook-based precoding of feedback information;

[0012] Figure 4 is a diagram showing a DNN (Deep Neural Network) model for predicting a channel matrix of one channel subset based on a channel matrix of another channel subset according to an embodiment;

[0013] Figure 5 and Figure 6 are graphical representations showing simulation results in 3D space and 2D space, respectively, illustrating correlation of channels in a selected subset of channels according to an embodiment;

[0014] Fig. 7A and Figure 7B is a graphical representation of simulation results showing two embodiments, and showing RB indices associated with any (e.g., each) cluster and representative RBs of any (e.g., each) cluster, and illustrating a minimum correlation coefficient associated with any (e.g., each) embodiment;

[0015] Figure 8 An example of a method for reducing signaling overhead in conjunction with reference signals is shown; and

[0016] Fig. 9 Another example of a method for reducing signaling overhead in conjunction with reference signals is shown. DETAILED DESCRIPTION

[0017] introduce

[0018] In the following detailed description, many specific details are set forth to provide a thorough understanding of the embodiments and / or examples disclosed herein. However, it will be understood that such embodiments and examples can be practiced without some or all of the specific details set forth herein. In other cases, well-known methods, procedures, components, and circuits are not described in detail to avoid obscuring the following description. In addition, embodiments and examples not specifically described herein can be practiced or combined with embodiments and other examples that are explicitly, implicitly, and / or inherently described, disclosed, or otherwise provided (collectively referred to as "provided") herein.

[0019] Although various embodiments are described and / or claimed herein in which devices, systems, apparatuses, etc. and / or any elements thereof perform an operation, process, algorithm, function, etc. and / or any portion thereof, it should be understood that any embodiment described and / or claimed herein assumes that any device, system, apparatus, etc. and / or any element thereof is configured to perform any operation, process, algorithm, function, etc. and / or any portion thereof.

[0020] Example Communication Systems and Apparatus

[0021] The methods, devices, and systems provided herein are well suited for communications involving wired and wireless networks. Wired networks are well known. Figures 1A to 1D An overview of various types of wireless devices and infrastructure is provided in which various elements of the network can utilize, perform, be arranged according to, and / or be adapted and / or configured for the methods, devices, and systems provided herein.

[0022] Figure 1A 1 is a diagram illustrating an example communication system 100 in which one or more disclosed embodiments may be implemented. The communication system 100 may be a multiple access system that provides content such as voice, data, video, messaging, broadcast, etc. to multiple wireless users. The communication system 100 may enable multiple wireless users to access such content by sharing system resources (including wireless broadband). For example, the communication system 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), single carrier FDMA (SC-FDMA), zero tail unique word DFT spread OFDM (ZT UW DTS-s OFDM), unique word OFDM (UW-OFDM), resource block filtered OFDM, filter bank multi-carrier (FBMC), etc.

[0023] like Figure 1AAs shown, the communication system 100 may include wireless transmit / receive units (WTRUs) 102a, 102b, 102c, 102d, RAN 104 / 113, CN 106 / 115, public switched telephone network (PSTN) 108, Internet 110 and other networks 112, but 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 “STA”) may be configured to transmit and / or receive wireless signals and may include user equipment (UE), a mobile station, a fixed or mobile subscriber unit, a subscription-based unit, a pager, a cellular phone, a personal digital assistant (PDA), a smart phone, a laptop, a netbook, a personal computer, a wireless sensor, a hotspot or Mi-Fi device, an Internet of Things (IoT) device, a watch or other wearable device, a head-mounted display (HMD), a vehicle, a drone, medical devices and applications (e.g., remote surgery), industrial devices and applications (e.g., robots and / or other wireless devices operating in the context of an industrial and / or automated process chain), a consumer electronic device, a device operating on a commercial and / or industrial wireless network, etc. Any of the WTRUs 102a, 102b, 102c, 102d may be interchangeably referred to as a UE.

[0024] The communication system 100 may also include a base station (BS) 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 to facilitate access to one or more communication networks, such as the CN 106 / 115, the Internet 110, and / or other networks 112. By way of example, the base stations 114a, 114b may be a base transceiver station (BTS), a Node B, an eNode B, a master Node B, a master eNode B, a gNB, an NR NodeB, 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.

[0025] 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), a relay node, 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 cells (not shown). These frequencies may be in a licensed spectrum, an unlicensed spectrum, or a combination of a licensed spectrum and an unlicensed spectrum. A cell may provide coverage of wireless services to a specific geographic area that may be relatively fixed or may vary over time. The cell may also be divided into cell sectors. For example, a cell associated with the base station 114a may be divided into three sectors. Therefore, in one 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 MIMO technology and may utilize multiple transceivers for each sector of the cell. For example, beamforming may be used to transmit and / or receive signals in a desired spatial direction.

[0026] 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).

[0027] More specifically, as described above, the communication 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, etc. 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 use Wideband CDMA (WCDMA) to establish the air interface 116. 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).

[0028] 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-APro).

[0029] In an embodiment, the base station 114a and the WTRUs 102a, 102b, 102c may implement a radio technology such as New Radio (NR) to establish NR radio access over the air interface 116.

[0030] 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 jointly implement LTE radio access and NR radio access, for example using dual connectivity (DC) principles. Thus, the air interface used by the 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., eNBs and gNBs).

[0031] In other embodiments, the base station 114a and the WTRUs 102a, 102b, 102c may implement a radio technology such as IEEE 802.11 (i.e., Wireless Fidelity (WiFi), IEEE 802.16 (i.e., Worldwide Interoperability for Microwave Access (WiMAX)), CDMA2000, CDMA2000 1X, 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 Evolution (GERAN), etc.

[0032] Figure 1AThe base station 114b in the example may be, for example, a wireless router, a master Node B, a master eNode B, or an access point, and may utilize any suitable RAT to facilitate wireless connectivity in a local area, such as a business location, a home, a vehicle, a campus, an industrial facility, an air corridor (e.g., for use by drones), a road, and the like. In one 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 another 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 a microcell or a femtocell. Figure 1A As shown, base station 114b may be directly connected to Internet 110. Therefore, base station 114b may not need to access Internet 110 via CN 106 / 115.

[0033] 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 different quality of service (QoS) requirements, such as different throughput requirements, latency requirements, fault tolerance requirements, reliability requirements, data throughput requirements, mobility requirements, etc. The CN 106 / 115 may provide call control, billing services, mobile location-based services, prepaid calls, Internet connectivity, video distribution, etc., and / or perform high-level security functions, such as user authentication. Although Figure 1A Not shown, but 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 or a different RAT as the RAN 104 / 113. 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) that employs GSM, UMTS, CDMA2000, WiMAX, E-UTRA, or WiFi radio technology.

[0034] 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 a circuit-switched telephone network that provides 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), the 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 communication 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 use the same RAT as the RAN 104 / 113 or a different RAT.

[0035] Some or all of the WTRUs 102a, 102b, 102c, 102d in the communication 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 via different wireless links). Figure 1A The illustrated WTRU 102c 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.

[0036] Figure 1B is a system diagram illustrating an example WTRU 102. Figure 1B As shown, the WTRU 102 may include, among other things, a processor 118, a transceiver 120, a transmit / receive element 122, a speaker / 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 peripherals 138. It will be appreciated that the WTRU 102 may include any sub-combination of the foregoing elements while remaining consistent with an embodiment.

[0037] 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 associated with a DSP core, a controller, a microcontroller, an application specific integrated circuit (ASIC), a field programmable gate array (FPGA) circuit, any other type of integrated circuit (IC), a state machine, etc. 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. Although Figure 1B The processor 118 and the transceiver 120 are depicted as separate components, but it will be appreciated that the processor 118 and the transceiver 120 may be integrated together in an electronic package or chip.

[0038] The transmit / receive element 122 may be configured to transmit signals to or receive signals from a base station (e.g., base station 114a) via an air interface 116. For example, in one 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 a transmitter / detector configured to transmit and / or receive, for example, IR, UV, or visible light signals. In another embodiment, the transmit / receive element 122 may be configured to transmit and / or receive both RF signals and optical signals. It will be appreciated that the transmit / receive element 122 may be configured to transmit and / or receive any combination of wireless signals.

[0039] Although the transmit / receive element 122 is Figure 1B Although depicted as a single element in the figure, the WTRU 102 may include any number of transmit / receive elements 122. More specifically, the WTRU 102 may employ MIMO technology. Thus, in one 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.

[0040] The transceiver 120 may be configured to modulate signals to be transmitted by the transmit / receive element 122 and to demodulate signals received by the transmit / receive element 122. As described 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 (e.g., such as NR and IEEE 802.11).

[0041] The processor 118 of the WTRU 102 may be coupled to and may receive user input data from: a speaker / microphone 124, a keypad 126, and / or a display / touchpad 128 (e.g., a liquid crystal display (LCD) display unit or an 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 a non-removable memory 130 and / or a removable memory 132. The non-removable memory 130 may include a random access memory (RAM), a read-only 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, etc. In other embodiments, the processor 118 may access information from and store data in a memory that is not physically located on the WTRU 102, such as on a server or a home computer (not shown).

[0042] The processor 118 may receive power from the power source 134 and may be configured to distribute the power to and / or control power to 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, etc.

[0043] 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 from a base station (e.g., base stations 114a, 114b) over the air interface 116 and / or determine its location based on the timing of receiving signals from two or more nearby base stations. It will be appreciated that the WTRU 102 may acquire location information by any suitable location-determination method while remaining consistent with an embodiment.

[0044] The processor 118 may also be coupled to other peripherals 138, which may include one or more software and / or hardware modules that provide additional features, functionality, and / or wired or wireless connectivity. For example, the peripherals 138 may include an accelerometer, an electronic compass, a satellite transceiver, a digital camera (for photos and / or video), a universal serial bus (USB) port, a vibration device, a television transceiver, a hands-free headset, module, a frequency modulation (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, etc. The peripheral device 138 may include one or more sensors, which may be gyroscopes, accelerometers, Hall effect sensors, magnetometers, orientation sensors, proximity sensors, temperature sensors, time sensors; geolocation sensors; altimeters, light sensors, touch sensors, magnetometers, barometers, gesture sensors, biometric sensors, and / or humidity sensors.

[0045] The WTRU 102 may include a full-duplex radio in which transmission and reception of some or all of the signals (e.g., associated with specific subframes for both 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 139 to reduce and or substantially eliminate self-interference via hardware (e.g., chokes) or signal processing via a processor (e.g., a separate processor (not shown) or via the processor 118). In an embodiment, the WTRU 102 may include a half-duplex radio in which transmission and reception of some or all of the signals (e.g., associated with specific subframes for both uplink (e.g., for transmission) or ...

[0046] Figure 1C 1 is a system diagram showing the RAN 104 and the CN 106 in accordance with an embodiment. As described above, the RAN 104 may employ an E-UTRA radio technology to communicate with the WTRUs 102a, 102b, 102c over the air interface 116. The RAN 104 may also be in communication with the CN 106.

[0047] 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 one embodiment, the eNode-Bs 160a, 160b, 160c may implement MIMO technology. Thus, for example, the eNode-B 160a may use multiple antennas to transmit wireless signals to and / or receive wireless signals from the WTRU 102a.

[0048] Each of the eNode-Bs 160a, 160b, 160c may be associated with a particular cell (not shown) and may be configured to handle radio resource management decisions, handover decisions, user scheduling in uplink (UL) and / or downlink (DL), etc. Figure 1C As shown, eNode-Bs 160a, 160b, 160c may communicate with each other via an X2 interface.

[0049] Figure 1C The illustrated CN 106 may include a mobility management entity (MME) 162, a serving gateway (SGW) 164, and a packet data network (PDN) gateway (or PGW) 166. While each of the foregoing elements is depicted as being part of the CN 106, it will be appreciated that any of these elements may be owned and / or operated by an entity other than the CN operator.

[0050] The MME 162 may be connected to each of the eNode-Bs 162a, 162b, 162c in the RAN 104 via an S1 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 the WTRUs 102a, 102b, 102c, etc. 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.

[0051] The SGW 164 may be connected to each of the eNode Bs 160a, 160b, 160c in the RAN 104 via an S1 interface. The SGW 164 may generally route and forward user data packets to and from the WTRUs 102a, 102b, 102c. The SGW 164 may perform other functions, such as anchoring the user plane during inter-eNode-B handovers, triggering paging when DL data is available for the WTRUs 102a, 102b, 102c, managing and storing the context of the WTRUs 102a, 102b, 102c, and the like.

[0052] 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.

[0053] 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) 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 other networks 112, which may include other wired and / or wireless networks owned and / or operated by other service providers.

[0054] Although the WTRU Figures 1A to 1D Although depicted as a wireless terminal, it is contemplated that in certain representative embodiments such a terminal may (eg, temporarily or permanently) employ a wired communications interface with a communications network.

[0055] In a representative embodiment, other network 112 may be a WLAN.

[0056] A WLAN in infrastructure basic service set (BSS) mode may have an access point (AP) for the BSS and one or more stations (STA) associated with the AP. The AP may access a distribution system (DS) or another type of wired / wireless network that loads traffic into and / or out of the BSS or has an interface thereto. Traffic originating from outside the BSS to the STA may be reached by the AP and may be delivered to the STA. Traffic from the STA to a destination outside the BSS may be sent to the AP to be delivered to the corresponding destination. Traffic between STAs within the BSS may be sent by 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. Traffic between STAs within the BSS may be considered and / or referred to as point-to-point traffic. Point-to-point traffic may be sent between the source STA and the destination STA using a direct link setup (DLS) (e.g., directly sent between them). In certain representative embodiments, the DLS may use 802.11e DLS or 802.11z tunnel DLS (TDLS). A WLAN using an independent BSS (IBSS) mode may not have an AP, and STAs (eg, all STAs) within or using the IBSS may communicate directly with each other. The IBSS communication mode may sometimes be referred to herein as an "ad hoc" communication mode.

[0057] When using the 802.11ac infrastructure mode of operation or a similar mode of operation, the AP can send beacons on a fixed channel, such as a primary channel. The primary channel can be a fixed width (e.g., a 20 MHz wide bandwidth) or a width dynamically set via signaling. The primary channel can be an operating channel of the BSS and can be used by STAs to establish a connection with the AP. In certain representative embodiments, carrier sense multiple access-collision avoidance (CSMA / CA) can be implemented, for example, in an 802.11 system. For CSMA / CA, STAs (e.g., each STA) including the AP can sense the primary channel. If the primary signal is sensed / detected by a particular STA and / or is determined to be busy, the particular STA can back off. One STA (e.g., only one station) can transmit in a given BSS at any given time.

[0058] A high throughput (HT) STA may communicate using a 40 MHz wide channel, for example, via a combination of a primary 20 MHz channel and adjacent or non-adjacent 20 MHz channels to form a 40 MHz wide channel.

[0059] Very high throughput (VHT) STA can support 20MHz, 40MHz, 80MHz and / or 160MHz wide channels. 40MHz and / or 80MHz channels can be formed by combining continuous 20MHz channels. A 160MHz channel can be formed by combining 8 continuous 20MHz channels, or by combining two discontinuous 80MHz channels, which can be referred to as an 80+80 configuration. For the 80+80 configuration, the data can be passed through a fragment parser after channel coding, which can divide the data into two streams. Inverse Fast Fourier Transform (IFFT) processing and time domain processing can be performed on each stream respectively. The stream can be mapped to two 80MHz channels, and the data can be transmitted by the transmitting STA. At the receiver of the receiving STA, the above-mentioned operation of the 80+80 configuration can be reversed, and the combined data can be sent to the media access control (MAC).

[0060] 802.11af and 802.11ah support operating modes below 1 GHz. The channel operating bandwidth and carrier are reduced in 802.11af and 802.11ah relative to those channel operating channels and carriers used in 802.11n and 802.11ac. 802.11af supports 5MHz, 10MHz and 20MHz bandwidths in TV white space (TVWS) spectrum, and 802.11ah supports 1MHz, 2MHz, 4MHz, 8MHz and 16MHz bandwidths using non-TVWS spectrum. According to a representative embodiment, 802.11ah can support instrument type control / machine type communication, such as MTC devices in macro coverage. MTC devices may have certain capabilities, for example, limited capabilities, including support for (e.g., only support for) certain and / or limited bandwidths. MTC devices may include batteries with battery life above a threshold (e.g., to maintain very long battery life).

[0061] A WLAN system that can support multiple channels and channel bandwidths (such as 802.11n, 802.11ac, 802.11af, and 802.11ah) includes a channel that can be designated as a primary channel. The primary channel may have a bandwidth equal to the maximum common operating bandwidth supported by all STAs in the BSS. The bandwidth of the primary channel may be set and / or limited by the STA that supports the minimum bandwidth operating mode among all STAs operating in the BSS. In the example of 802.11ah, for STAs (e.g., MTC-type devices) that support (e.g., only support) a 1MHz mode, the primary channel may be 1MHz wide, even if the AP and other STAs in the BSS support 2MHz, 4MHz, 8MHz, 16MHz, and / or other channel bandwidth operating modes. Carrier sensing and / or network allocation vector (NAV) settings may depend on the state of the primary channel. If the primary channel is busy, for example, due to a STA (which only supports a 1MHz operating mode) transmitting to the AP, the entire available band may be considered busy even if most of the band remains idle and may be available.

[0062] In the United States, the available frequency band that can be used by 802.11ah is 902MHz to 928MHz. In South Korea, the available frequency band is 917.5MHz to 923.5MHz. In Japan, the available frequency band is 916.5MHz to 927.5MHz. The total bandwidth available for 802.11ah is 6MHz to 26MHz, depending on the country code.

[0063] Figure 1D1 is a system diagram showing the RAN 113 and the CN 115 according to an embodiment. As described above, the RAN 113 may employ 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.

[0064] 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 one embodiment, the gNBs 180a, 180b, 180c may implement MIMO technology. For example, the gNBs 180a, 180b may utilize beamforming to transmit signals to and / or receive signals from the gNBs 180a, 180b, 180c. Thus, for example, the gNB 180a 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 located on an unlicensed spectrum, while the remaining component carriers may be located on a licensed spectrum. In an embodiment, the gNBs 180a, 180b, 180c may implement coordinated multi-point (CoMP) technology. For example, the WTRU 102a may receive coordinated transmissions from the gNB 180a and gNB 180b (and / or gNB 180c).

[0065] The WTRUs 102a, 102b, 102c may communicate with the gNBs 180a, 180b, 180c using transmissions associated with scalable parameter sets. For example, the 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 the gNBs 180a, 180b, 180c using subframes or transmission time intervals (TTIs) of varying or scalable lengths (e.g., containing different numbers of OFDM symbols and / or lasting different lengths of absolute time) .

[0066] 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 a standalone configuration, the WTRUs 102a, 102b, 102c may communicate with the gNBs 180a, 180b, 180c without also accessing other RANs (e.g., such as the eNode Bs 160a, 160b, 160c). In a standalone configuration, the WTRUs 102a, 102b, 102c may use one or more of the gNBs 180a, 180b, 180c as mobility anchors. In a standalone configuration, the WTRUs 102a, 102b, 102c may communicate with the gNBs 180a, 180b, 180c using signals in an unlicensed band. In a non-standalone configuration, the WTRU 102a, 102b, 102c may communicate / connect with the gNB 180a, 180b, 180c while also communicating / connecting with another RAN, such as the eNode-B 160a, 160b, 160c. For example, the WTRU 102a, 102b, 102c may implement the DC principle to communicate with one or more gNBs 180a, 180b, 180c and one or more eNode-Bs 160a, 160b, 160c substantially simultaneously. In a non-standalone configuration, the eNode-B 160a, 160b, 160c may serve as a mobility anchor for the WTRU 102a, 102b, 102c, and the gNB 180a, 180b, 180c may provide additional coverage and / or throughput to serve the WTRU 102a, 102b, 102c.

[0067] 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, user scheduling in uplink (UL) and / or downlink (DL), support for network slicing, dual connectivity, interworking between NR and E-UTRA, routing of user plane data towards a user plane function (UPF) 184a, 184b, routing of control plane information towards an access and mobility management function (AMF) 182a, 182b, etc. As shown in FIG. Figure 1D As shown, gNBs 180a, 180b, and 180c may communicate with each other via an Xn interface.

[0068] Figure 1DThe illustrated CN 115 may include at least one AMF 182a, 182b, at least one UPF 184a, 184b, at least two session management functions (SMFs) 183a, 183b, and possibly data networks (DNs) 185a, 185b. While each of the foregoing elements is depicted as part of the CN 115, it will be appreciated that any of these elements may be owned and / or operated by an entity other than the CN operator.

[0069] The AMF 182a, 182b may be connected to one or more of the gNBs 180a, 180b, 180c in the RAN 113 via the N2 interface and may serve as a control node. For example, the AMF 182a, 182b may be responsible for authenticating users of the WTRU 102a, 102b, 102c, supporting network slicing (e.g., handling different PDU sessions with different requirements), selecting a specific SMF 183a, 183b, managing registration areas, terminating NAS signaling, mobility management, etc. The AMF 182a, 182b may use network slicing to customize CN support for the WTRU 102a, 102b, 102c based on the type of service the WTRU 102a, 102b, 102c is utilizing. For example, different network slices may be established for different use cases, such as services that rely on ultra-reliable low latency (URLLC) access, services that rely on enhanced massive mobile broadband (eMBB) access, services for machine type communication (MTC) access, etc. 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 WiFi).

[0070] The SMF 183a, 183b may be connected to the AMF 182a, 182b in the CN 115 via the N11 interface. The SMF 183a, 183b may also be connected to the UPF 184a, 184b in the CN 115 via the 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 addresses, managing PDU sessions, controlling policy enforcement and QoS, providing downlink data notification, etc. The PDU session type may be IP-based, non-IP-based, Ethernet-based, etc.

[0071] The UPF 184a, 184b may be connected to one or more of the gNBs 180a, 180b, 180c in the RAN 113 via the N3 interface, 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. The UPF 184, 184b may perform other functions, such as routing and forwarding packets, enforcing user plane policies, supporting multi-homed PDU sessions, handling user plane QoS, buffering downlink packets, providing mobility anchoring, etc.

[0072] 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) 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 other networks 112, which may include other wired and / or wireless networks owned and / or operated by other service providers. In one embodiment, the WTRUs 102a, 102b, 102c may be connected to local data networks (DNs) 185a, 185b via the UPFs 184a, 184b via the N3 interfaces to the UPFs 184a, 184b and the N6 interfaces between the UPFs 184a, 184b and the DNs 185a, 185b.

[0073] Given that Figures 1A to 1D and Figures 1A to 1D In the embodiment of the present invention, one or more or all of the functions described herein for one or more of the following may be performed by one or more simulation devices (not shown): WTRU 102a to 102d, base station 114a to 114b, eNode-B 160a to 160c, MME 162, SGW 164, PGW 166, gNB 180a to 180c, AMF 182a to 182b, UPF 184a to 184b, SMF 183a to 183b, DN 185a to 185b and / or any other device described herein. The simulation device may be one or more devices configured to simulate one or more or all of the functions described herein. For example, the simulation device may be used to test other devices and / or simulate network and / or WTRU functions.

[0074] The simulation device can be designed to implement one or more tests of other devices in a laboratory environment and / or an operator network environment. For example, one or more simulation devices can perform one or more or all functions when fully or partially implemented and / or deployed as part of a wired and / or wireless communication network to test other devices within the communication network. One or more simulation devices can perform one or more or all functions when temporarily implemented / deployed as part of a wired and / or wireless communication network. The simulation device can be directly coupled to another device for testing purposes, and / or can use over-the-air wireless communication to perform testing.

[0075] One or more simulation devices can perform one or more (including all) functions when not implemented / deployed as part of a wired and / or wireless communication network. For example, the simulation device can be used for testing scenarios in a test laboratory and / or a wired and / or wireless communication network that is not deployed (e.g., testing) to implement testing of one or more components. One or more simulation devices can be test equipment. The simulation device can use direct RF coupling and / or wireless communication via RF circuits (e.g., which can include one or more antennas) to transmit and / or receive data.

[0076] Channel State Information Report

[0077] The channel state information may include any of the following: a channel quality index (CQI), a rank indicator (RI), a precoding matrix index (PMI), an L1 channel measurement (e.g., a reference signal received power (RSRP), such as L1-RSRP, or a signal-to-interference-plus-noise ratio (SINR)), a CSI-RS resource indicator (CRI), a synchronization signal (SS) and physical broadcast channel (SS / PBCH) block resource indicator (SSBRI), a layer indicator (LI), and / or any other measurement quantity measured by the WTRU (e.g., UE) based on a configured reference signal (e.g., a CSI-RS or SS / PBCH block or any other reference signal).

[0078] CSI Reporting Framework

[0079] A WTRU (e.g., UE) may be configured to report CSI, for example, via an uplink control channel on a physical uplink control channel (PUCCH) or as requested by a BS (e.g., gNB) on an uplink physical shared channel (UL PUSCH) grant. For example, depending on the configuration, the CSI-RS may cover the full bandwidth of a bandwidth part (BWP), or only a small portion thereof. Within the CSI-RS bandwidth, the CSI-RS may be configured in any (e.g., every) physical resource block (PRB) or every other PRB. In the time domain, CSI-RS resources may be configured periodically, semi-persistently, or aperiodically. Semi-persistent CSI-RS is similar to periodic CSI-RS, except that the resource may be (de)activated by a MAC CE; and the WTRU (e.g., UE) reports relevant measurements only when the resource is activated. For aperiodic CSI-RS, the WTRU (e.g., UE) is triggered to report the measured CSI-RS on PUSCH as requested in the DCI (downlink control information). Periodic reports are carried on the PUCCH, while semi-persistent reports may be carried on the PUCCH or PUSCH. The reported CSI may be used by the scheduler in, for example, allocating the best resource blocks based on the time-frequency selectivity of the channel, determining the precoding matrix, beams and / or transmission mode, and selecting the appropriate modulation and coding scheme (MCS). The reliability, accuracy, and timeliness of WTRU (e.g., UE) CSI reporting may be critical to meeting Ultra-Reliable and Low-Latency Communication (URLLC) service requirements.

[0080] A WTRU (e.g., UE) may be configured with a CSI configuration, which may include one or more CSI reporting settings, resource settings, and / or a link between one or more CSI reporting settings and one or more resource settings. The link may be implemented, for example, by providing a pointer to the resource configuration within the CSI reporting setting. Figure 2 Examples of CSI reporting settings, resource settings, and linked configurations are shown.

[0081] In the CSI configuration, any of the following configuration parameters may be provided:

[0082] N≥1 CSI report setups 211 , M≥1 resource setups 213 , and a CSI measurement setup 215 linking the N CSI report setups 211 with the M resource setups 213 .

[0083] - The CSI report settings 211 may include at least one of the following:

[0084] · Temporal behavior: aperiodic or periodic / semi-persistent.

[0085] • Frequency granularity, at least for PMI and CQI.

[0086] • CSI report type (eg, PMI, CQI, RI, CRI, etc.).

[0087] • If PMI is reported, the PMI type (Type I or II) and codebook configuration.

[0088] - Resource settings 213 may include at least one of the following:

[0089] · Temporal behavior: aperiodic or periodic / semi-persistent.

[0090] • RS type (eg, for channel measurement or interference measurement).

[0091] • S ≥ 1 resource sets, and any (eg, each) resource set may contain K resources, where K is an integer that can be preconfigured.

[0092] - A CSI measurement setup 215 may include a linked pair of any of the following:

[0093] A CSI reporting setting.

[0094] A resource setting.

[0095] For CQI, refer to the transmission scheme setting.

[0096] - For CSI reporting of component carriers, any of the following frequency granularities may be supported:

[0097] Broadband CSI.

[0098] Partial-band CSI.

[0099] Sub-band CSI.

[0100] Codebook-based precoding

[0101] Figure 3 The basic concept of codebook-based precoding of feedback information is shown. The feedback information may include a precoding matrix index (PMI) which may be referred to as a codeword index in the codebook, such as Figure 3 shown.

[0102] like Figure 3As shown, the codebook may include a set of precoding vectors / matrices for any (e.g., each) rank and multiple antenna ports, and any (e.g., each) precoding vector or matrix may have its own index so that the receiver can inform the transmitter of the preferred precoding vector / matrix index. Compared to non-codebook-based precoding, codebook-based precoding may suffer from performance degradation due to its limited number of precoding vectors / matrices. However, the main advantage of codebook-based precoding is the possibility of reducing control signaling / feedback overhead. Table 1 shows an example codebook for 2Tx.

[0103]

[0104] Table 1

[0105] CSI Processing Standards

[0106] A CSI processing unit (CPU) may be referred to as a minimum CSI processing unit, and a WTRU (e.g., UE) may support one or more CPUs (e.g., N CPUs). A WTRU (e.g., UE) with N CPUs may estimate N CSI feedback calculations in parallel, where N may be the WTRU (e.g., UE) capability. If a WTRU (e.g., UE) is requested to estimate more than N CSI feedbacks simultaneously, the WTRU (e.g., UE) may (e.g., only) perform N of the highest priority CSI feedbacks and may not estimate the remaining feedbacks.

[0107] The start and end of the CPU may be determined based on the CSI reporting type (e.g., aperiodic, periodic, semi-persistent) as any of the following:

[0108] For aperiodic CSI reporting, the CPU may be occupied starting from the first OFDM symbol after the physical downlink control channel (PDCCH) trigger until the last OFDM symbol of the PUSCH carrying the CSI report.

[0109] For periodic and semi-persistent CSI reporting, the CPU may be occupied starting from the first OFDM symbol of one or more associated measurement resources (no earlier than the CSI reference resource) until the last OFDM symbol of the CSI report.

[0110] The amount of CPU occupied may differ based on the CSI measurement type (e.g., beam-based or non-beam-based), such as any of the following:

[0111] Non-beam related reports:

[0112] When there are K CSI-RS resources in the CSI-RS resource set used for channel measurement, K CPUs.

[0113] Beam-related reports (e.g., "cri-RSRP" (CSI-RS resource indicator reference signal received power), "ssb (synchronization signal block)-index-RSRP", or "none"):

[0114] Since the CSI calculation complexity is low, one CPU is used regardless of the number of CSI-RS resources in the CSI-RS resource set used for channel measurement.

[0115] ο “None” is used for P3 operation or non-periodic Tracking Reference Signal (TRS) transmission.

[0116] For aperiodic CSI reporting with a single CSI-RS resource, one CPU may be occupied.

[0117] • For reporting CSI for K CSI-RS resources, K CPUs may be occupied because the WTRU (eg, UE) may (eg, needs to) perform CSI measurement on any (eg, each) CSI-RS resource.

[0118] When the number of unused CPUs (N u ) is less than the number of CPUs required for CSI reporting (N r ), any of the following WTRU (e.g., UE) behaviors may be used:

[0119] • For example, in case of uplink control information (UCI) on PUSCH without data / HHARQ (Hybrid Automatic Repeat Request), the WTRU (eg, UE) may drop N_r-N_uCSI reports based on priority.

[0120] • For example, in other cases, the WTRU (eg, UE) may report dummy information in the Nr-Nu CSI report based on priority to avoid rate matching processing for PUSCH.

[0121] Artificial Intelligence (AI)

[0122] Artificial intelligence can be broadly defined as behavior exhibited by machines. This behavior can, for example, mimic cognitive functions to perceive, reason, adapt, and act.

[0123] Machine Learning (ML)

[0124] General principles of ML

[0125] Machine learning may refer to a type of algorithm that solves problems based on empirical learning ("data") without being explicitly programmed ("configured rule sets"). Machine learning can be considered a subset of AI. Different machine learning paradigms can be envisioned based on the nature of the data or feedback available to the learning algorithm. For example, supervised learning methods may involve learning a function that maps inputs to outputs based on labeled training examples, where any (e.g., each) training example can be a pair consisting of an input and a corresponding output. For example, unsupervised learning methods may involve detecting patterns in data without pre-existing labels. For example, reinforcement learning methods may involve performing a series of actions in an environment to maximize cumulative rewards. In some embodiments, machine learning algorithms may be applied using a combination or interpolation of the above methods. For example, a semi-supervised learning method may use a combination of a small amount of labeled data and a large amount of unlabeled data during training. In this regard, semi-supervised learning is between unsupervised learning (without labeled training data) and supervised learning (with (e.g., only) labeled training data).

[0126] Deep Learning (DL)

[0127] Deep learning refers to a class of machine learning algorithms that use artificial neural networks (e.g., DNNs) loosely inspired by biological systems. DNNs are a special class of machine learning models inspired by the human brain, in which the input is linearly transformed and passed through a nonlinear activation function multiple times. DNNs typically include multiple layers, wherein any (e.g., each) layer includes a linear transformation and a given nonlinear activation function. DNNs can be trained using training data via a backpropagation algorithm. Recently, DNNs have shown state-of-the-art performance in a variety of fields (e.g., speech, vision, natural language, etc.) and in various machine learning settings (such as supervised, unsupervised, and semi-supervised). The term AIML-based method / processing can refer to achieving behavior and / or compliance with requirements by learning based on data without explicitly configuring the order of steps or actions. Such methods can enable learning of complex behaviors that may be difficult to specify and / or implement when using traditional methods.

[0128] Clustering

[0129] Clustering is one of the (e.g., most basic) tasks in unsupervised machine learning, and has a wide variety of applications in various fields. The clustering task can be intended to divide several data samples into multiple separate groups so that the data samples of each group / cluster are more similar / more relevant to any other (e.g., each other) relative to those data samples in other groups / clusters. Among several clustering methods, K-means clustering has aroused great interest because of its simplicity and effectiveness. K-means is an iterative lightweight algorithm that is generally suitable for clustering data samples distributed around some centroids. Although K-means is an old-fashioned method, it has recently been used and demonstrated its effectiveness in processing many problems between various fields, including signal processing, data mining, and image processing, to name a few.

[0130] Reduce reference signal overhead

[0131] For downlink scheduling and link adaptation purposes for both SU-MIMO and MU-MIMO, accurate knowledge of the channel may be used (e.g., required). This may be achieved using DL CSI-RS reference signals to enable channel estimation at the WTRU (e.g., UE) and by feeding back the estimated CSI (e.g., implicit CSI: CQI, PMI, RI, LI) in the WTRU (e.g., UE) CSI report. Since 5G NR supports up to 32 antenna ports, there is a large overhead associated with the DL CSI-RS reference signals and the corresponding UL CSI reports. This overhead may (e.g., is expected to further) increase with increasing system bandwidth and number of antennas in B5G massive MIMO systems.

[0132] In certain scenarios (e.g., certain antenna configurations and channel conditions), the channel responses / CSI corresponding to different Tx antenna ports may be highly correlated. Similarly, high correlation between channel responses / CSI in different subbands may be observed in the frequency domain. When high correlation of CSI occurs (in the spatial domain or the frequency domain), the high correlation may be exploited to reduce the density of CSI-RS used (e.g., required) to accurately estimate CSI at the WTRU (e.g., UE).

[0133] Aspects to be addressed herein include any of the following actions: reducing RS overhead by transmitting / activating (e.g., only) on a reduced set of antenna ports while achieving performance close to that of full-port transmission, determining which antenna ports are selected for reduced-port CSI-RS transmission and which protocols are selected to indicate the reduced set to a BS (e.g., gNB), performing CSI feedback reporting based on the reduced set of antenna ports, reducing RS overhead by determining a reduced CSI-RS pattern in the frequency domain, determining a reduced CSI-RS pattern in the frequency domain, reporting the selected pattern, and performing CSI feedback reporting based on the reduced pattern in the frequency domain.

[0134] Representative RS overhead based on spatial correlation

[0135] To reduce CSI-RS overhead, the BS (e.g., gNB) may transmit CSI-RS on a selected subset of antenna ports, for example, instead of performing full-port CSI-RS transmission. The WTRU (e.g., UE) may (e.g., then) estimate a reduced channel matrix associated with the selected ports. The estimated reduced channel may be used for different purposes in different deployment scenarios. For example,

[0136] a. AI model at (e.g., only) WTRU (e.g., UE): The WTRU (e.g., UE) may use the estimated reduced channel response / frequency response / coefficient / matrix (hereinafter sometimes referred to as "channel" to avoid unnecessary redundancy) of the selected (first) subset to predict the channel associated with the unselected (second) subset using the AI ​​model for CSI prediction. The WTRU (e.g., UE) may use the estimated channel based on the first subset in conjunction with the predicted channel of the second subset, for example, to form an entire channel matrix for further processing at the WTRU (e.g., UE). For example, for Type I or Type I ICSI feedback, the WTRU (e.g., UE) may use the entire channel matrix to perform PMI measurements.

[0137] b. AI model at (e.g., only) BS (e.g., gNB) and joint processing between WTRU (e.g., UE) and BS (e.g., gBB): The WTRU (e.g., UE) may directly send back the estimated reduced channel corresponding to the selected (first) subset. The BS (e.g., gNB) may use the reduced estimated channel associated with the first subset to predict the second subset channel using the AI ​​model for CSI prediction at the BS (e.g., gNB). The BS (e.g., gNB) may form the full channel matrix and, for example, may use it for precoding purposes (as opposed to conventional approaches).

[0138] The WTRU (eg, UE) may also be configured to directly derive / report a precoder index (PMI) associated with the estimated reduced channel of the selected ports (first subset).

[0139] AI Model Description

[0140] DNN methods can be used to solve the CSI prediction problem. Figure 4 The layout of the DNN model according to an embodiment is shown. Given an initial (full) estimated channel Two reduced channel matrices can be constructed and Where P1+P2=P and P1≥P2. represents the subset of indices containing the selected antenna ports, where j=0, ..., P1-1, p j，1 denotes the jth port index associated with the first subset. Similarly, The subset containing the unselected antenna port indices may be represented by, where for j=0, ..., P2-1, p i，2 can represent the i-th port index associated with the second subset. By definition, [P1] and [P2] can be two disjoint subsets, that is, The DNN method (e.g., then) can be designed to be able to A ) is associated with the estimated channel response input, the prediction is related to the second subset (H B ) associated channel response / CSI.

[0141] Model training.

[0142] For training purposes, the full channel matrix H f N samples are collected in, that is, for n=1,...,N, Can be based on To construct the input-output pair To train DNN.

[0143] refer to Figure 4 , the matrix H can be constructed in a specific way A and H B , so that the column indices (transport port indices) follow a specific pattern, e.g., the indices are sorted in two subsets, i.e., and This may reduce the feedback overhead when using a DNN model at a BS (e.g., gNB). In this case, the WTRU (e.g., UE) may (e.g., needs to) report (e.g., only report) the selected port index and the associated channel coefficients. Such information may be sufficient to know the predicted channel H B . Recall that the DNN model can be placed at the WTRU (e.g., UE) or the BS (e.g., gNB) or both. The proposed framework can be viewed as a means for CSI-RS overhead reduction, channel prediction / mapping from one antenna subset to another, and uplink feedback overhead reduction.

[0144] The DNN weights (θ) can be optimized to minimize a specific loss function L. For example, the loss function can be chosen as

[0145]

[0146] Where f(.) represents the DNN function.

[0147] Model feasibility.

[0148] In some cases, in the first subset (H A ) and the channel response / CSI of the second subset (H B ) can exist between the channel responses / CSI of the two antenna subsets [P1] and [P2]. ​​This relationship / mapping can be determined by how the two antenna subsets [P1] and [P2] are spatially related. For example, in a static communication scenario, it has been theoretically shown that such a mapping exists.

[0149] The performance of an AI / ML model may depend on how well the first (input) subset is selected. Therefore, it may be useful (e.g., important) to determine the best representative first subset [P1] that can be used to predict channel coefficients associated with the second subset [P2]. ​​In other words, before training the model, the subset [P1] should be determined in a way that specifies the inherent relationship between the input and output.

[0150] Representative Antenna Port Selection

[0151] Representativeness determination of subsets

[0152] A WTRU (eg, UE) may be configured to determine a subset of antenna ports.

[0153] The WTRU (e.g., UE) may be configured with a new higher layer parameter (referred to herein as CSISpatial-PortIndication) which may be included in a new message (referred to herein as CSIPred-ReportConFig). The value of this parameter may indicate to the WTRU (e.g., UE) whether CSI spatial prediction at the WTRU (e.g., UE) is enabled. If the parameter indicates that CSI spatial prediction is not enabled, the WTRU (e.g., UE) may operate (e.g., assuming that the BS (e.g., gNB) transmits CSI-RS using a default time-frequency pattern.

[0154] When the higher layer parameter CSISpatial-PortIndication indicates that CSI spatial prediction is enabled, the WTRU (e.g., UE) may operate in a case where the BS (e.g., gNB) does not utilize a default time-frequency pattern for CSI-RS transmission (e.g., assuming this case).

[0155] In one option, the WTRU (e.g., UE) is configured with antenna ports that are used by the BS (e.g., gNB) to transmit CSI-RS for channel measurement (P1). The WTRU (e.g., UE) may operate with (e.g., only) CSI-RS transmitted on the indicated antenna port index (e.g., assuming this case).

[0156] In another option, a parameter corresponding to the maximum number of active antenna ports (maxP1) used by the BS (e.g., gNB) for CSI-RS transmission may be provided to the WTRU (e.g., UE). The WTRU (e.g., UE) may (e.g., then) determine a set of antenna ports P1, where P1≤maxP1. The WTRU (e.g., UE) may (e.g., then) determine P1 disjoint sets / groups / clusters of antenna ports, where P1≤maxP1. For p=1, ..., P1, the antenna ports belonging to the pth set have a spatial relationship with each other and the representative port within the pth set, at least in terms of channel coefficients. The representative port associated with any (e.g., each) set may be defined as, for example, the port with the minimum distance or maximum correlation to all other ports in the same set / group / cluster. This is defined later in the description. The WTRU (e.g., UE) may determine the extent of such spatial relationship between antenna ports within a set based on the maximum number of such sets (maxP1) configured by the network. For example, the WTRU (eg, UE) may use cross-correlation values ​​between channel coefficients corresponding to different antenna ports to determine their spatial relationship.

[0157] The WTRU (e.g., UE) may respond to the BS (e.g., gNB) with a set of P1 identified antenna ports, where P1 ≤ maxP1. This subset [P1] allows the channel coefficients P for all antenna ports to be determined, for example using a suitable DNN, by measuring the channel coefficients on the CSI-RS transmitted on this particular subset of antenna ports.

[0158] According to an embodiment, the WTRU (e.g., UE) may be configured with a parameter maxsubseterror that represents the maximum allowed error between channel coefficients of members of a set (cluster / group) of antenna ports. The error may be a Frobenius norm, a mean square error, etc. The WTRU (e.g., UE) may (e.g., then) determine a minimum number of such sets that may be determined, where the members of each group have channel coefficients that differ from each other by an amount less than the configured parameter maxsubseterror. The WTRU (e.g., UE) may (e.g., then) report the number P1 of such sets / clusters / groups, and / or the indices of the P1 antenna ports that may be used to perform channel measurements on all member antenna ports belonging to those sets.

[0159] The WTRU (e.g., UE) may report channel coefficients to the BS (e.g., gNB). According to an embodiment, the WTRU (e.g., UE) may use a DNN to estimate the channel coefficients (P) for all antenna port indexes based on measurements made on a subset of antenna ports P1. The WTRU (e.g., UE) may then report the channel coefficients for all antenna port indexes.

[0160] According to an embodiment, the WTRU (e.g., UE) may report (e.g., report only) the channel coefficient for an antenna port index, e.g., directly estimating its value based on the received CSI-RS. This may correspond to the port index used by the BS (e.g., gNB) on which the CSI-RS is sent. The WTRU (e.g., UE) may (e.g., additionally) report the identities of the antenna ports of all members of any (e.g., each) of the P1 antenna port sets / clusters / groups. The BS (e.g., gNB) may (e.g., then) be able to estimate the channel coefficients for all P antenna ports, e.g., by estimating the missing values ​​using a DNN.

[0161] If the WTRU (e.g., UE) determines to report channel coefficients for P1 antenna ports such that P1 ≤ maxP1, where maxP1 represents the maximum number of antenna ports to be used by the BS (e.g., gNB) for CSI-RS transmission, then (e.g., then) the WTRU (e.g., UE) may (e.g., is required to) use all pre-configured uplink resources to report the channel coefficients. The WTRU (e.g., UE) may (e.g., then) utilize resources in a pre-configured manner, e.g., the first P1 resource in time out of the maxP1 allocated resources. Representative pre-configuration of possible subsets

[0162] The following sections describe port selection based on preconfigured subsets.

[0163] A WTRU (eg, UE) may be pre-configured with multiple antenna port grouping sets, such as with index n1. Any (eg, each) set may contain multiple antenna port subsets, such as with index n2. Any (eg, each) antenna port index belonging to a subset may have a specific CSI spatial relationship with other members of the subset.

[0164] According to an embodiment, any (e.g., each) set may be formed, for example, as a subset containing the same number of representative antenna ports (P1). According to an embodiment, any (e.g., each) set may correspond to an antenna port grouping satisfying the following conditions: for example, the maximum difference between the channel coefficients within the subset is less than a preconfigured value, for example, maxsubseterror.

[0165] The formation of sets and subsets may be such that, for example, one set may include antenna port groups that any (e.g., each) include N1 clusters, another set may include antenna port groups that any (e.g., each) include N2 clusters, and there is a set that may include antenna port groups where the maximum difference between the channel coefficients of the group members is less than a preconfigured threshold (e.g., maxsubseterror). For example, within the first set may be multiple subsets that (e.g., each) have N1 clusters, where the respective antenna port memberships may be different. This may be illustrated with the following example: for a total of 64 antenna port indices, a set may include groups of 8 antenna port clusters, where (e.g., each) such group includes a different combination of antenna port indices.

[0166] The WTRU (e.g., UE) may first select a set that meets the requirements configured by the network, such as, the maximum deviation of channel coefficients between subset members is less than maxsubseterror, the number of representative antenna ports corresponding to CSI-RS transmissions on the same port is set to a specific value (P1), etc. According to an embodiment, the WTRU (e.g., UE) may (e.g., then) select a subset within the selected set to meet any additional criteria. For example, the WTRU (e.g., UE) may select a subset in which the maximum difference between channel coefficients within a set of antenna groups is less than a configured threshold (e.g., maxsubseterror), and (e.g., then) select a subset in which the maximum difference between groups is the smallest. According to an embodiment, the WTRU (e.g., UE) may randomly select a subset from the set.

[0167] According to an embodiment, the WTRU (e.g., UE) may be configured to select groupings of antenna ports such that the maximum difference between the channel coefficients of the group members is less than a preconfigured value, e.g., maxsubsterror. Within a preconfigured set of such groupings that satisfy a given condition, the WTRU (e.g., UE) may select a grouping of antenna port indices that minimizes the number of antenna port clusters (e.g., maximizes the size of the membership of any (e.g., each) individual antenna port cluster).

[0168] The WTRU (e.g., UE) may communicate its selection of the set and subset to the BS (e.g., gNB). The WTRU (e.g., UE) may communicate its selection of the set and subset, for example, by communicating its selection of the index n1 and According to an embodiment, when a WTRU (e.g., UE) is configured with a requirement (e.g., a desired number of clusters) of a BS (e.g., gNB) to set a first index (n_1), (e.g., then) the WTRU (e.g., UE) may select a member of the identified subset and (e.g., only) transmit a second index According to an embodiment, when a WTRU (e.g., UE) is configured with a maximum number of clusters for channel state measurement by a BS (e.g., gNB), (e.g., then) the WTRU (e.g., UE) may determine that multiple sets may satisfy the requirement. The WTRU (e.g., UE) may select a set that satisfies the condition from the pre-configured sets based on either: (i) optimizing a sub-criteria, such as a minimum number of clusters or a maximum inter-member similarity, i.e., a minimum maximum difference between group members, or (ii) randomly.

[0169] The following sections describe a method by which a WTRU (eg, UE) dynamically determines a subset of antenna ports.

[0170] Determining the best representative antenna port subset may be important for several reasons. First, such a subset may produce minimal feedback overhead while maintaining a target performance (e.g., ∈-accuracy relative to a full-port setting). Second, a good selection of candidates for the first subset may (e.g., significantly) improve the performance of the DNN approach, which in turn may improve overall system performance, e.g., block error rate (BLER), throughput, etc. In this section, the process by which a WTRU (e.g., UE) determines the entries of a subset [P1] will be described.

[0171] Mechanism for determining antenna port subsets

[0172] The WTRU (eg, UE) may be configured, for example, based on an initial estimated full-port channel matrix To determine and report a subset of antenna ports

[0173] According to an embodiment, the WTRU (e.g., UE) may determine the size of P1 based on a pre-configured metric (e.g., correlation coefficient, normalized mean square error (NMSE), etc. Increasing P1 may (e.g., be expected to) improve the performance of the DNN while increasing the associated overhead. Conversely, decreasing P1 may reduce prediction performance but may reduce overhead.

[0174] The WTRU (eg, UE) may apply an unsupervised learning method to the full-port channel matrix To determine the antenna port set For example, the WTRU (eg, UE) may apply a clustering method to cluster the total number of antenna ports into separate groups in a manner that maximizes the intra-group correlation while minimizing the inter-group correlation.

[0175] According to an embodiment, a WTRU (eg, a UE) may use K-means to convert the full-port channel matrix Clustering is in N rdimensional space. It should be noted that P1 may be equivalent to the number of centroids, which is an input to the K-means algorithm. The WTRU (e.g., UE) may determine the number of clusters / centroids / selected ports by iteratively performing measurements on a possible preconfigured number of clusters, for example, P1 may take one of the predefined values ​​of transmit antenna ports (2, 4, 8, 12, 16, 24, 32). According to an embodiment, the WTRU (e.g., UE) may determine any value of P1 that is lower than some maximum preconfigured value P1max. For example, the WTRU (e.g., UE) may start by setting P1 to P1max and (e.g., then) calculate the minimum correlation coefficient p for each cluster i , for i = 0, ..., P1-1, then ρ i The minimum value (denoted as ρ min ) and the pre-configured correlation threshold ρ th For comparison. If ρ min (P1)>ρ th , then the WTRU (e.g., UE) may reduce the number of clusters until the minimum number of clusters / ports that satisfies the relevance test is determined. min (P1)<ρ th , the WTRU (eg, UE) may increase the number of clusters.

[0176] The WTRU (eg, UE) may (eg, then) determine the As an example, the port with the smallest distance or largest correlation to the centroid of any (e.g., each) cluster can be selected. For i=0, ..., P1-1, let represents the centroid identified from K-means. The WTRU (e.g., UE) may select port p j，1 ,,like

[0177]

[0178] And h ji is the full matrix H associated with port i f , where port i belongs to cluster j.

[0179] According to an embodiment, the WTRU (eg, UE) may select / recommend the size of the subset P1 based on the number of PUCCH / PUSCH payload bits (B) or the physical downlink shared channel (PDSCH) performance (eg, BLER).

[0180] If the WTRU (eg, UE) is configured to select from pre-configured subsets, then (eg, then) the WTRU (eg, UE) may first determine the clusters and associated ports, and then select the subset with the largest number of ports from the different clusters.

[0181] Representative adaptive update of the determined subset

[0182] The determined subset may change based on the degree of time variation of the channel. The WTRU (e.g., UE) may be configured to determine when a previously determined subset may (e.g., needs to) be updated based on channel-related measurements. In this case, the DNN model may be designed to handle variable input and variable output dimensions (e.g., using a convolutional neural network (CNN) with dropout). According to an embodiment, the WTRU (e.g., UE) may be configured with different sets of DNN models; any one (e.g., each one) may have a different P1 value.

[0183] -The WTRU (e.g., UE) may track the reduced channel For example, a WTRU (e.g., UE) may store an initial estimated channel H A , denoted as H A [0] In any (e.g., each) subsequent time slot t, the WTRU (e.g., UE) may calculate the time interval of the WTRU (e.g., UE) based on the function f(H A [0],H A [t]) to perform the measurement. For example, the function can be NMSE, such as,

[0184] ·

[0185] where ||.|| F Denotes the Frobenius norm. The WTRU (e.g., UE) may compare the NMSE obtained at any (e.g., every) time with a certain pre-configured threshold. If the measured NMSE is greater than a certain pre-configured NMSE threshold, the WTRU (e.g., UE) may trigger reporting of full-port transmission.

[0186] - According to an embodiment, a WTRU (eg, UE) may request full-port CSI-RS transmission based on PDSCH capabilities For example, if the BLER drops below a predefined BLER threshold.

[0187] According to an embodiment, the WTRU (eg, UE) may store a vector associated with the centroid Where j = 0, ..., P1-1. For example, suppose is a matrix that keeps the centroids in its columns. The WTRU (e.g., UE) may calculate the centroids based on the function f(C,HA ) to perform measurements. For example, the WTRU (e.g., UE) may determine whether previously determined antenna ports are still associated with their clusters, or whether some of them have become closer to another cluster. According to an embodiment, the WTRU (e.g., UE) may use a correlation function to determine new port assignments,

[0188] ·f(C,H A )=C H H A

[0189] Among them, C and H A Any (eg, each) column of may (eg, be assumed to) have unit norm. For example, if the number of ports to be assigned to a new cluster is greater than some preconfigured value, the WTRU (eg, UE) may trigger reporting of full-port transmission.

[0190] - A WTRU (e.g., UE) may request an all-port transmission based on channel measurements. For example, if the estimated Doppler exceeds a certain pre-configured threshold, the WTRU (e.g., UE) may trigger a report of an all-port transmission. In another example, if the change in the estimated angle of arrival exceeds a certain pre-configured threshold, the WTRU (e.g., UE) may trigger a report.

[0191] - The WTRU (e.g., UE) may store the CSI associated with the first subset and (e.g., only) request CSI-RS transmission on the second subset to update the first subset instead of full port transmission. For example, if the WTRU (e.g., UE) detects that the determined subset may be (e.g., needs to be) updated, the WTRU (e.g., UE) may request CSI-RS transmission to estimate H at time t B And (for example, then) based on H B [l]undH A [t-1] to update the first subset.

[0192] Numerical results

[0193] To demonstrate the effectiveness of the proposed framework, a numerical example for using K-means is now presented. The simulation parameters employed may be as follows. A clustered delay line (CDL)-A channel model is used, where the delay spread is set to 300ns, the carrier frequency is set to 4GHz and the number of transmit antenna ports is set to 128. Both the base station and the WTRU (e.g., UE) are equipped with uniform linear arrays where the antenna elements are spaced half a wavelength apart. A wideband setting may be used (e.g., assumed), where the channel matrix may be obtained by averaging the channel over 20 resource blocks.

[0194] The size of the first subset (number of centroids) can be set to 16. Consider the following two scenarios: N r =2, which corresponds to clustering in 2D space; and N r =3, which corresponds to clustering in 3D space. Figure 5 and Figure 6 The results shown are for Scenario I and Scenario II, respectively. The cluster centroids are depicted by black "x's" and the antenna ports closest to any (e.g., each) of the 16 clusters are depicted by red circles. These ports can be considered as representative ports that can (e.g., need to) signal back to the BS (e.g., gNB). The minimum correlation coefficients associated with Scenario I and Scenario II were measured to be 0.66 and 0.72, respectively. Recall that the correlation can be improved by increasing P1 (the number of centroids) and can be reduced by decreasing P1.

[0195] Representative indication of a subset of antenna ports

[0196] The WTRU (eg, UE) may be configured to indicate the selected antenna port (index).

[0197] Explicit indication of the identified subset

[0198] According to an embodiment, a WTRU (e.g., UE) may be configured, instructed, or requested to report information of an antenna port subset (e.g., an identified antenna port subset) based on measurement and / or evaluation of a measurement reference signal (e.g., CSI-RS, TRS, etc.). In the following, the term antenna port may be used interchangeably with antenna, virtual antenna, logical antenna, antenna port number, antenna port index, and physical antenna. Some or more of the following may apply:

[0199] - A subset of antenna ports may be referred to as a CSI reporting quantity (eg, antenna port index).

[0200] - A subset of antenna port indices may be reported by the WTRU (eg, UE) as preferred or required antenna ports for measuring RS.

[0201] The maximum number of antenna port indices in the report may be determined based on any of the following:

[0202] • The capacity of the uplink feedback resources configured, used or determined.

[0203] • The number of antenna ports configured by higher layers (eg, Radio Resource Control (RRC), Medium Access Control-Control Element (MAC-CE)) for measuring RSs that may be targets of RS overhead reduction.

[0204] - WTRU (e.g., UE) capability (e.g., AIML capability) reporting of RS overhead reduction for the identified antenna port subset may be triggered by the BS (e.g., gNB) via L1 signaling (e.g., DCI) or configured to be reported periodically or semi-persistently via higher layer signaling. The antenna port subset may include the full antenna port set. (For example, in this case) the WTRU (e.g., UE) may skip reporting the antenna port subset and the absence of signal may be treated as a report using the full antenna port set.

[0205] According to an embodiment, the WTRU (e.g., UE) may determine to report information of the identified antenna port subset if (e.g., at this time) any of the following conditions may be met:

[0206] - The identified subset of antenna ports is different from previous reports.

[0207] - Based on the measurement quality of the current antenna port subset being below a threshold. (For example, in this case) the WTRU (e.g., UE) may indicate to the BS (e.g., gNB) that the measurement quality (e.g., channel measurement quality) is below a threshold. This indication may be viewed or interpreted as an indication that the full set of antenna ports may (e.g., need to) be preferred for channel measurement.

[0208] - The channel estimation / prediction quality from the current subset of antenna ports is below a threshold.

[0209] - The AIML model used for channel estimation or measurement accuracy is below a threshold.

[0210] The WTRU (e.g., UE) may indicate the identified antenna subset through uplink signaling to be used for CSI-RS transmission. The CSI report may include the identified subset and / or the associated CSI. The signaling may be done (e.g., explicitly) through modified UCI, using PUCCH and / or PUSCH, or implicitly using specific PUCCH, random access channel (RACH), or sounding reference signal (SRS) resources.

[0211] - According to an embodiment, a WTRU (e.g., UE) may be configured with different formats of UCI resources. Different formats may have different numbers of bits, resource blocks, etc. to indicate the identified antenna subset information. For example, the format may indicate the identified antenna subset index and the corresponding CSI or part thereof.

[0212] - According to an embodiment, the format may indicate including the identified subset and the associated PMI based on the reduced size CSI.

[0213] - The WTRU (eg, UE) may transmit back to the selected antenna port via PUCCH or PUSCH.

[0214] - The feedback may include CSI reports associated with the (reduced) set of antennas.

[0215] - If the WTRU (eg, UE) reaches the maximum number of centroids (P1), but does not meet the required correlation threshold, it may report this explicitly or implicitly as part of the reporting mechanism. A fallback to the legacy configuration may be used.

[0216] - If the determined P1 is less than maxP1, it has an impact on the uplink report.

[0217] - According to an embodiment, the selected antenna subset may be associated with certain pre-configured indexes to facilitate efficient feedback between the base station and the terminal.

[0218] - According to an embodiment, the WTRU (eg, UE) may indicate an increase or decrease in the number of antennas in a subset through a simple up / down command.

[0219] The following sections describe channel measurement reporting for a subset of antenna ports.

[0220] According to an embodiment, the BS (e.g., gNB) may instruct or request the WTRU (e.g., UE) to report channel measurements of a subset of antenna ports. Based on the channel measurements of the subset of antenna ports, the BS (e.g., gNB) may estimate channel information of other antenna ports, for example, by using an AIML model trained at the BS (e.g., gNB) and / or the WTRU (e.g., UE).

[0221] One or more types of CSI reports (or channel measurement reports) may be used, where a first type of CSI report may include channel information for all antenna ports and / or a second type of CSI report may include channel information for a subset of antenna ports.

[0222] The first type of CSI reporting may be configured with a first time period (eg, periodic or semi-persistent; long term), and / or the second type of CSI reporting may be configured with a second time period (eg, aperiodic, short term).

[0223] For example, when a WTRU (eg, UE) is triggered or requested to report, it may be indicated or informed which subset of antenna ports may (eg, need to) be reported.

[0224] When a WTRU (e.g., UE) reports CSI, the type of CSI report may be determined based on any of the following:

[0225] - Determined uplink resource type For example, when PUSCH is used for CSI reporting, a first type of CSI reporting may be used; otherwise, a second type of CSI reporting may be used.

[0226] - Determined uplink resource amount For example, when the CSI reporting resource can carry a number of information bits greater than a threshold, the first type of CSI report may be used; otherwise, the second type of CSI report may be used.

[0227] - Dropping of a portion of the CSI may or may not be used. For example, if the uplink resource has sufficient capacity to report the CSI of all antenna ports, a first type of CSI report may be used; otherwise, a second type of CSI report may be used, where the number of antenna ports used for CSI reporting may be determined based on the uplink resource capacity.

[0228] In the following, the term CSI may be used interchangeably with channel measurement, channel measurement of all antenna ports, channel measurement of an antenna port subset, channel matrix, CSI report, CSI report setting, CSI measurement resource, and CSI report quantity (e.g., PMI, RI, CQI, LI).

[0229] CSI feedback reporting based on antenna port subset

[0230] A WTRU (e.g., UE) may be configured to derive CSI (or an amount thereof) based on reference signal measurements from a first set of antenna ports. For example, the first set of antenna ports may be a subset of the total number of antenna ports configured for the WTRU (e.g., UE). For example, a second set of antenna ports may be defined and / or determined such that a combination of the first set of antenna ports and the second set of antenna ports may be equal to the total number of antenna ports configured for the WTRU (e.g., UE). The WTRU (e.g., UE) may be configured to predict CSI (or an amount thereof) for the second set of antenna ports. The WTRU (e.g., UE) may use the CSI derived from the first set of antenna ports to predict the CSI for the second set of antenna ports. According to an embodiment, the first set of antenna ports may be referred to as a "measurement subset" and / or the second set of antenna ports may be referred to as a "prediction subset". According to an embodiment, the WTRU (e.g., UE) may be (e.g., explicitly) configured with a measurement subset and a prediction subset. According to an embodiment, the WTRU (e.g., UE) may determine which antenna ports may be included in (e.g., constitute) a measurement subset and which antenna ports may be included in (e.g., constitute) a prediction subset. The WTRU (e.g., UE) may be configured with criteria for determining the subsets. For example, the WTRU (e.g., UE) may partition the subsets to achieve any of the following: partitioning is performed such that the CSI prediction error on the second set of antenna ports is minimized. For example, the NMSE between the predicted CSI and / or the actual CSI may be below a threshold and / or partitioning such that the reference signal transmission overhead is minimized and / or the CSI feedback transmission overhead is minimized.

[0231] The WTRU (e.g., UE) may derive a CSI quantity (e.g., PMI) based on at least one antenna port from a first set (e.g., a measurement subset) and / or the WTRU (e.g., UE) may transmit a CSI report associated with (e.g., comprising) a portion of antenna ports of the first antenna port set.

[0232] According to an embodiment, a WTRU (e.g., UE) may be configured to receive CSI-RS associated with a subset of antenna ports out of a total number of configured antenna ports. For example, such a subset of antenna ports may correspond to a first antenna port set (e.g., a “measurement subset”). The WTRU (e.g., UE) may be configured to determine a CSI quantity (e.g., PMI or any other implicit CSI) associated with the first antenna port set. The WTRU (e.g., UE) may be configured to report the determined CSI through the first antenna port set. According to an embodiment, the WTRU (e.g., UE) may be configured to include an (e.g., explicit) indication of the first antenna port set, for example, together with the CSI report. According to an embodiment, the WTRU (e.g., UE) may be pre-configured with a set of PUCCH resources, and any (e.g., each) PUCCH resource may be associated with a different subset of antenna ports. The WTRU (e.g., UE) may determine the PUCCH resources for CSI transmission based on the determination of the first antenna port set. For example, such an embodiment may be beneficial in reducing RS transmission overhead and / or CSI feedback overhead. A BS (e.g., a gNB) may determine CSI associated with a second set of antenna ports based on CSI reports received for a first set of antenna ports, for example using a predictor AIML model.

[0233] A WTRU (e.g., a UE) may derive and / or transmit a CSI report containing channel measurements (e.g., a channel matrix or a quantity derived therefrom) based on an indication of a first antenna port set (e.g., a measurement subset) and / or a portion of antenna ports that (e.g., comprise) the first antenna port set.

[0234] Any of the above embodiments may also be extended to the case of (e.g., explicit) CSI reporting, where the WTRU (e.g., UE) may be configured to derive and report (e.g., explicit) CSI for a subset of antenna ports out of the total number of configured antenna ports. According to an embodiment, the WTRU (e.g., UE) may be configured to perform any of the following steps: determining a first set of antenna ports using one or more of the methods described herein, deriving (e.g., explicit) CSI associated with the first set of antenna ports, compressing (e.g., explicit) CSI, and transmitting compressed CSI associated with the first set of antenna ports. For example, such an embodiment may be beneficial in reducing RS transmission overhead and / or CSI feedback overhead. The BS (e.g., gNB) may employ an AIML model to convert received CSI on a subset of antenna ports into CSI on the full set of antenna ports.

[0235] A WTRU (e.g., UE) may derive a first CSI quantity (e.g., PMI) based on at least one antenna port from a first set (e.g., a measurement subset) and derive a second CSI quantity (e.g., PMI) based on one or more antenna ports from a second set (e.g., a prediction subset), and the WTRU (e.g., UE) may transmit a CSI report having the first CSI quantity and the second CSI quantity and an indication of an antenna port portion of (e.g., constituting) the first antenna port set and / or the second antenna port set.

[0236] According to an embodiment, a WTRU (e.g., a UE) may be configured to receive CSI-RS associated with a subset of antenna ports out of the total number of configured antenna ports. For example, such a subset of antenna ports may correspond to a first antenna port set (e.g., a "measurement subset"). The WTRU (e.g., a UE) may be configured to determine two types of CSI. A first CSI quantity (e.g., a PMI or any other implicit CSI thereof) may be associated with a first antenna port set. For example, a WTRU (e.g., a UE) may be configured to derive CSI based on a CSI-RS received on a first antenna port set. A second CSI quantity (e.g., a PMI or any other implicit CSI thereof) may be associated with a second antenna port set. For example, a WTRU (e.g., a UE) may be configured to predict CSI on a second antenna port set based on CSI derived from a first antenna port set. For example, such a prediction may be performed using an AIML model. For example, an AIML model at a WTRU (e.g., a UE) may be configured by a network. For example, an AIML model at a WTRU (e.g., a UE) may be predefined. For example, the AIML model at the WTRU (eg, UE) may be based on the WTRU (eg, UE) implementation.The WTRU (eg, UE) may be configured to report both the first CSI quantity and the second CSI quantity in a CSI report.

[0237] According to an embodiment, the WTRU (e.g., UE) may indicate that a CSI report contains at least one quantity derived based on a measurement of a CSI-RS and / or another CSI quantity based on a prediction of the CSI in the spatial domain. For example, the WTRU (e.g., UE) may indicate an association between the CSI and a subset of antenna ports to which the CSI applies. According to an embodiment, the WTRU (e.g., UE) may be configured to implicitly or explicitly indicate antenna ports that may be included in (e.g., constitute) a first set of antenna ports and a second set of antenna ports.

[0238] A WTRU (e.g., UE) may transmit a CSI report containing channel measurements (e.g., a channel matrix or a throughput thereof) based on at least one antenna port from a first set (e.g., a measurement subset) and one or more antenna ports from a second set (e.g., a prediction subset), and the WTRU (e.g., UE) may transmit the CSI report along with an indication of the antenna ports constituting the first antenna port set and / or the second antenna port set.

[0239] Any of the above embodiments may also be extended to the case of (e.g., explicit) CSI reporting, where the WTRU (e.g., UE) may be configured to derive and / or report (e.g., explicit) CSI for a first antenna port subset and / or a second antenna port subset. According to an embodiment, the WTRU (e.g., UE) may be configured to perform any of the following steps: determine a first antenna port set and a second antenna port set using one or more of the methods described herein, derive (e.g., explicit) CSI associated with the first antenna port set and / or the second antenna port set, compress the (e.g., explicit) CSI, and / or transmit compressed CSI associated with the first antenna port set and the second antenna port set. For example, such embodiments may be beneficial in reducing RS transmission overhead and / or CSI feedback overhead.

[0240] Frequency domain representation for reducing RS overhead

[0241] Background: CSI-RS can be configured to partially or fully cover the bandwidth of the assigned bandwidth part (BWP). Within the configured bandwidth, CSI-RS can be configured for transmission in every resource block (RB) (density = 1) or every other RB (density = 1 / 2), with additional configurations for sets or resource blocks (e.g., even or odd). Given a target channel estimation performance, CSI-RS overhead can be reduced by dynamically controlling the CSI-RS frequency density.

[0242] One possible approach is to start with density (ρ) = 1 and adaptively change the density based on WTRU (e.g., UE) measurements. For example, given an initial estimated channel (atρ=1), where k=1, ..., K and K is the number of RBs, the WTRU (e.g., UE) may construct a compact channel matrix where h k is the vectorized H[K]. The WTRU (eg, UE) may determine a first set of RBs K1 out of a total number of RBs K,, which may be used to predict a channel associated with another set of size K2. For example, the matrix may be formed and where K1 and K2 are two disjoint subsets, where |K1|+|K2|=K, |K1|≤|K2| and K1∩K2=0. For example, a DNN can be trained to take the input Mapping to output

[0243] Representative RB subset selection

[0244] A WTRU (e.g., UE) may be configured with different patterns of CSI-RS resources in the frequency domain. For example, there may be N different configurations of frequency densities, where one configuration includes CSI-RS resources in every RB, another configuration includes CSI-RS resources in every other RB, another configuration includes CSI-RS resources in every third RB, and so on, up to a configuration that includes CSI-RS resources in every N RBs.

[0245] For any (e.g., each) configured frequency density, a WTRU (e.g., UE) may be configured with different configurations of CSI-RS resources. For example, one configuration may include CSI-RS in every N RBs starting from the first RB, another configuration may include CSI-RS resources in every N RBs starting from the second RB, and so on, up to a configuration that may include CSI-RS resources in every N RBs starting from the Nth RB.

[0246] Initially, and periodically, the BS (e.g., gNB) may transmit CSI-RS on a default frequency resource pattern. For example, the BS (e.g., gNB) may transmit CSI-RS on each RB within the BWP. The WTRU (e.g., UE) may estimate channel coefficients using this maximum set of resources for CSI-RS transmission. The WTRU (e.g., UE) may (e.g., then) determine the correlation between different RBs within the BWP. For example, the WTRU (e.g., UE) may determine the mean square error between channel estimates for different RB combinations and conclude from this that by specifying N groups of RBs, it is ensured that the maximum difference in channel coefficients within any (e.g., each) group / cluster is less than a pre-configured value.

[0247] If the WTRU (e.g., UE) determines that the correlation between a pair of RBs is greater than a preconfigured value, it may (e.g., then) report to the BS (e.g., gNB) to eliminate CSI-RS transmission on one of the RBs. According to an embodiment, the WTRU (e.g., UE) may make this determination based on another metric (e.g., mean square error between channel coefficients corresponding to the pair of RBs).

[0248] The WTRU (eg, UE) may extend this determination to more than one pair of RBs, eg, N RBs, and (eg, then) identify such groups of N RBs having similar channel coefficients to each other based on some metric.

[0249] Due to the observed correlation between RBs, the WTRU (eg, UE) may (eg, then) be able to determine channel coefficients for all RBs within a BWP based on channel measurements on a subset of frequency resources used for CSI-RS transmission.

[0250] The WTRU (e.g., UE) may signal to the BS (e.g., gNB) the RB indices that it may use (e.g., needs to) to measure the channel coefficients to determine the channel coefficients for the entire BWP. According to an embodiment, the WTRU (e.g., UE) may provide the indices of all RBs in the set. According to an embodiment, a plurality of such RB combinations may have been pre-configured by the BS (e.g., gNB). The WTRU (e.g., UE) may select one of the RB combinations and signal its index to the BS (e.g., gNB).

[0251] A WTRU (e.g., UE) may request CSI-RS transmissions to a BS (e.g., gNB) on a default frequency mode. The WTRU (e.g., UE) may do this, for example, when it determines that channel coefficient estimates from a subset of RBs are insufficient to provide an estimate of the channel coefficients for the full BWP at a pre-required level of accuracy. The WTRU (e.g., UE) may make this determination, for example, based on observing the BLER of downlink shared channel transmissions.

[0252] According to an embodiment, a WTRU (e.g., UE) may be configured with a temporal pattern of CSI-RS transmissions such that a BS (e.g., gNB) cycles over different frequency patterns. For example, a BS (e.g., gNB) may transmit CSI-RS on a default frequency pattern (e.g., on every RB or on every other RB) at the beginning of a cycle of L consecutive transmissions, and (e.g., then) transmit on a reduced subset of RBs previously identified by the WTRU (e.g., UE) for (L-1) occasions. According to an embodiment, a WTRU (e.g., UE) may be configured with a temporal pattern of CSI-RS transmissions that starts with a default frequency pattern at a first instance, followed by a CSI-RS frequency density pattern N1, N2, N3 on consecutive transmission instances within the cycle, and then returns to the default frequency pattern at the beginning of the next cycle.

[0253] Representative RB subsets

[0254] The WTRU (e.g., UE) may be configured to determine and indicate a representative set of RBs to be used for CSI-RS transmission in an allocated BWP. The WTRU (e.g., UE) may determine the set of RBs in a manner that reduces CSI-RS overhead while maintaining target performance (e.g., channel estimation or PDSCH performance).

[0255] Mechanism for determining RB subsets

[0256] The WTRU (e.g., UE) may determine the minimum number of RBs and their indices / positions based on a pre-configured correlation / NMSE threshold or a channel estimation performance related metric configured by the BS (e.g., gNB). The determined RBs may be used to predict the channel coefficients associated with other (unselected) RBs in the allocated BWP. The WTRU (e.g., UE) may use a DNN approach or linear interpolation to predict the channels associated with the other RBs. According to an embodiment, the WTRU (e.g., UE) may determine which approach to use based on the calculated correlation of the identified RBs.

[0257] The WTRU (e.g., UE) can estimate the channel size of all RBs by initial full estimation. A clustering method is applied to determine a representative set of RBs, i.e., k=1, ..., K, where K is the number of RBs in the allocated BWP. According to an embodiment, the WTRU (e.g., UE) may cluster / group together any (e.g., each) set of related RBs using K-means. The WTRU (e.g., UE) may tune the number of clusters (K1) until a global correlation threshold test is met. For example, in K-means, K1 is equivalent to the number of centroids. The WTRU (e.g., UE) may change the number of centroids until a K1 that satisfies a predefined criterion (e.g., correlation coefficient or / and reporting overhead constraint) is found. According to an embodiment, the WTRU (e.g., UE) may set K1 based on a pre-configured density. For example, the WTRU (e.g., UE) may be configured with one of eight possible density levels between 0 and 1, and the WTRU (e.g., UE) may determine K1 RB indices from the configured BWP based on the configured density.

[0258] The WTRU (eg, UE) may recommend a density that achieves a predefined correlation threshold. For example, the WTRU (eg, UE) may report one of the possible preconfigured densities such that the target channel estimation performance is met.

[0259] The WTRU (e.g., UE) may determine the representative RB index for each cluster by measuring the distance between the cluster centroid and the RB closest to the centroid or by looking at the cosine similarity between the CSI associated with the closest RB and the centroid. For example, let [h1, ..., h4] denote the cluster with centroid The N associated with one of the resulting clusters r N t dimensional channel vector. The WTRU (e.g., UE) may determine the representative RB index in the cluster by selecting the RB index with the minimum distance or maximum correlation to the cluster centroid. For example, the WTRU (e.g., UE) may determine the RB index as

[0260]

[0261] Where all i∈{1, 2, 3, 4}.

[0262] The WTRU (e.g., UE) may report (e.g., only) the index of the representative RB of any (e.g., each) identified cluster. The WTRU (e.g., UE) may indicate whether the RBs associated with the same cluster are contiguous. Such information may, for example, help the BS (e.g., gNB) to adjust the density or select the subcarrier position within any (e.g., each) RB, or may be useful for scheduling aspects.

[0263] Numerical results

[0264] To demonstrate the effect of K-means in the frequency domain, two simulation scenarios with different density values ​​are implemented. Fig. 7A and Figure 7B Results for both scenarios are shown. The simulation parameters employed are as follows. The CDL-A channel model is employed, the carrier frequency is set to 4 GHz, the number of transmit antennas is set to 32, and the number of receive antennas is set to 3. Both the BS and the WTRU (e.g., UE) may be equipped with uniform linear arrays where antenna elements are spaced half a wavelength apart. The bandwidth portion size may be set to 32 resource blocks.

[0265] Consider the following two scenarios: Scenario I, where the delay spread is set to 300 ns and the number of clusters is set to 8 RBs corresponding to a density of 0.25, and in Scenario II, the delay spread is set to 30 ns and the number of clusters is set to 4 RBs corresponding to a density of 0.125. Fig. 7A and Figure 7B The results shown are for scenario I and scenario II, respectively. The two figures show the RB indices associated with any (e.g., each) cluster. In addition, the representative RB of any (e.g., each) cluster is depicted with a red circle. The representative RB is determined based on the calculated correlation between any (e.g., each) RB and the centroid of the same cluster. These are the RB indices that can (e.g., need to) signal back to the BS (e.g., gNB). For example, in Figure 7BIn , the representative RB indices are (5, 14, 22, 29). The minimum correlation coefficients associated with scenario I and scenario II are measured to be 0.85 and 0.88, respectively. Recall that the correlation can be controlled by tuning K1 (the number of centroids). It can also be seen that Figure 7B The RBs of each cluster in appear to be continuous, but each cluster has a variable size, whereas Fig. 7A The RBs in scenario I are discontinuous due to the large delay spread.

[0266] Representative report of identified RB subsets

[0267] The following sections describe the determination of RB subsets by a WTRU (eg, UE).

[0268] According to an embodiment, a WTRU (e.g., UE) may be configured, requested, or indicated to report a subset of RBs for which the WTRU (e.g., UE) may (e.g., need to) measure a channel to obtain channel information of a configured bandwidth. For example, a BWP may be configured, used, or determined for the WTRU (e.g., UE) to measure CSI and report the measured CSI. Using the reported information, the BS (e.g., gNB) may transmit a measurement reference signal in the subset of RBs indicated or reported by the WTRU (e.g., UE). Any of the following may apply:

[0269] -The indication (or report) associated with the RB subset may include an index of the RB or an associated CSI report. This may be determined based on which node (e.g., BS (e.g., gNB) and / or WTRU (e.g., UE)) is AIML capable.

[0270] - The indication (or reporting) of the RB subset may be based on one or more subband indices reported. For example, the WTRU (e.g., UE) may report or indicate the subband indices for which reference signals may need to be measured. For example, one or more subbands may be configured, defined, or used in a BWP, and the WTRU (e.g., UE) may report a bitmap indicating which subbands need to measure reference signals to obtain channel information for the BWP.

[0271] The subband size (or minimum subband size) may be determined based on determined uplink resources (e.g., capacity, uplink resource type) and / or predetermined conditions (e.g., whether discarding occurs, measurement quality, accuracy of AIML model). Smaller subband sizes may require a larger number of bits to indicate an RB subset.

[0272] - The indication (or reporting) of RB subsets may be based on one or more clusters, where a cluster may be defined or indicated as a starting RB and a number of consecutive RBs within a BWP. One or more clusters may be mutually exclusive (eg, non-overlapping in the frequency domain).

[0273] The number of clusters (or the maximum number of clusters) may be determined based on the determined uplink resources (e.g., capacity, uplink resource type) and / or predetermined conditions (e.g., whether discarding occurs, measurement quality, accuracy of the AIML model). A larger number of clusters may require more bits to indicate the RB subset.

[0274] - The indication (or reporting) of the RB subset may be the interval of adjacent RBs. For example, the first RB subset may be RBs located every 2 RBs (eg, even RBs or odd RBs), and the second RB subset may be RBs located every 3 RBs.

[0275] Hereinafter, the term measurement reference signal may be used interchangeably with a demodulation reference signal (eg, DMRS), a tracking reference signal (TRS), a phase tracking reference signal (PTRS), and an SRS.

[0276] The following sections describe the determination of RB subsets at a BS (e.g., gNB).

[0277] According to an embodiment, a BS (e.g., gNB) may indicate or determine a subset of RBs for a WTRU (e.g., UE) to measure and / or report CSI. Based on the channel measurement of the subset of RBs, the BS (e.g., gNB) may estimate channel information of other RBs by using an AIML model trained at the BS (e.g., gNB) and / or WTRU (e.g., UE).

[0278] One or more types of CSI reports (or channel measurement reports) may be used, where a first type of CSI report may include channel information for all RBs in a BWP and a second type of CSI report may include channel information for a subset of RBs in a BWP.

[0279] - A first type of CSI report may be configured with a first time period (eg, periodic or semi-persistent; long term), and a second type of CSI report may be configured with a second time period (eg, aperiodic, short term).

[0280] - When a WTRU (eg, UE) is triggered or requested to report, it may be indicated or informed which subset of RBs may (eg, need to) be reported.

[0281] In the case where the WTRU (e.g., UE) reports CSI (e.g., at this time), the type of CSI report may be determined based on any of the following:

[0282] - Determined uplink resource type For example, when PUSCH is used for CSI reporting, a first type of CSI reporting may be used; otherwise, a second type of CSI reporting may be used.

[0283] - Determined uplink resource amount For example, when the CSI reporting resource can carry a number of information bits greater than a threshold, the first type of CSI report may be used; otherwise, the second type of CSI report may be used.

[0284] - Dropping of a portion of the CSI may or may not be used. For example, if the uplink resource has sufficient capacity to report CSI for all RBs in the BWP, a first type of CSI report may be used; otherwise, a second type of CSI report may be used, where the number of RBs used for CSI reporting may be determined based on the uplink resource capacity.

[0285] CSI feedback report based on dynamic RB subset selection

[0286] A WTRU (e.g., UE) may be configured to derive CSI (or an amount thereof) based on CSI-RS transmitted on a subset of resource blocks (RBs) within a configured bandwidth portion. The CSI report may be a PMI associated with a representative RB and information related to different identified RB clusters / groups. According to an embodiment, the CSI report may include a (compressed) reduced channel matrix for (e.g., only) a representative RB, and (e.g., then) a full channel matrix associated with all RBs may be predicted using a linear (e.g., interpolation) or non-linear (e.g., DNN) approach.

[0287] The WTRU (eg, UE) may derive a CSI quantity (eg, PMI) based on the estimated channel associated with the selected RB.

[0288] According to an embodiment, a WTRU (e.g., UE) may be configured to receive CSI-RS on a subset of RBs (e.g., recommended by the WTRU (e.g., UE)). The WTRU (e.g., UE) may be configured to determine and report a PMI associated with the selected subset of RBs. This may be equivalently considered as downsampling the frequency domain, but where the sampling locations (the selected RBs) are determined and recommended by the WTRU (e.g., UE) (rather than uniformly downsampling or averaging the channels of any (e.g., each) RB cluster / group). The WTRU (e.g., UE) may be configured to include an (e.g., explicit) indication of the index of the RBs associated with any (e.g., each) cluster / group to assist in the precoding process. According to an embodiment, if the determined RBs associated with any (e.g., each) cluster / group are indicated as contiguous, the WTRU (e.g., UE) may be configured to derive and report the PMI of the representative RB as well as the size of any (e.g., each) cluster and the starting RB index of any (e.g., each) cluster.

[0289] The WTRU (eg, UE) may be configured to directly report the estimated channel associated with the selected RB.

[0290] According to an embodiment, the WTRU (e.g., UE) may be configured to send back a reduced channel matrix (which may be a compressed version) associated with a pre-configured RB subset. This may be beneficial for high correlation scenarios, e.g., low density and high correlation per cluster. The BS (e.g., gNB) may use a CSI prediction method (e.g., supervised such as DNN or unsupervised such as interpolation / extrapolation).

[0291] The following sections describe falling back to traditional clustering.

[0292] The WTRU (e.g., UE) may be configured to recommend the use of dynamic clustering or traditional clustering. Here, traditional based clustering refers to clustering / grouping contiguous RBs with a fixed subband size, for example, the number of RBs in each cluster is the same. Dynamic clustering may include clusters with contiguous or discontinuous RBs, and the number of RBs in each cluster may be variable. The WTRU (e.g., UE) may determine / recommend whether to use dynamic clustering or traditional clustering. For example, the WTRU (e.g., UE) may compare the resulting downlink overhead and uplink feedback overhead associated with the two methods and recommend the one with the lower overhead.

[0293] Figure 8 An example of a method 800 implemented in a WTRU 102 including multiple antennas and corresponding antenna ports is shown.

[0294] According to an embodiment, the WTRU 102 may be configured to receive configuration information from the network for selecting a first subset of antenna ports of the WTRU on which to perform reference signal processing, for example based on spatial correlation between antennas of the WTRU (810).

[0295] According to an embodiment, the WTRU 102 may be configured to estimate the channel conditions of the WTRU based on, for example, reference signals received on all antenna ports (820).

[0296] According to an embodiment, the WTRU 102 may be configured to select a first subset of antenna ports based on estimated channel conditions, for example for all antennas and received configuration information (830).

[0297] According to an embodiment, the WTRU 102 may be configured to send data disclosing identities of antenna ports in the first subset of antenna ports to the network (840).

[0298] According to an embodiment, the WTRU 102 may be configured to perform reference signal processing on a first subset of antenna ports to estimate channel conditions corresponding to antenna ports in the first subset of antenna ports (850).

[0299] According to an embodiment, the WTRU 102 may be configured to estimate channel conditions corresponding to the remaining antenna ports of the WTRU based on the channel conditions corresponding to the antenna ports in the first subset of antenna ports (860).

[0300] According to an embodiment, the selection of the first antenna subset may be based on a threshold that satisfies a maximum difference between channel conditions of antenna ports in the first antenna port subset.

[0301] According to an embodiment, the received configuration information may include one or more of the following: (1) a maximum number of antenna ports that can be included in the first antenna port subset; (2) a method for determining the first antenna port subset; and (3) a measure of spatial correlation between the first antenna port subset and a second antenna port subset, the second antenna port subset including antenna ports that are not in the first antenna port subset.

[0302] According to an embodiment, the selection of the first antenna subset may be performed using an artificial intelligence / machine learning process.

[0303] According to an embodiment, the artificial intelligence / machine learning process may utilize a DNN model.

[0304] According to an embodiment, the WTRU may be configured to: determine a condition indicating a change in a channel condition that satisfies a criterion; and alter the first subset of antenna ports in response to such determination.

[0305] According to an embodiment, the condition indicating a change in the channel condition satisfying the criterion may include a data transfer error rate exceeding a threshold value.

[0306] Fig. 9 An example of the method 900 implemented in a WTRU 102 including multiple antennas and corresponding antenna ports is shown.

[0307] According to an embodiment, the WTRU 102 may be configured to receive configuration information indicating one or more channel state information (CSI) spatial prediction parameters from a network node (910).

[0308] According to an embodiment, the WTRU 102 may be configured to receive a first plurality of reference signals transmitted from a plurality of antenna ports of a network node (920).

[0309] According to an embodiment, the WTRU 102 may be configured to perform / estimate one or more first CSI measurements based on a plurality of received reference signals (930).

[0310] According to an embodiment, the WTRU 102 may be configured to determine a first subset of antenna ports of a plurality of antenna ports of a network node and / or one or more parameters associated with the first subset of antenna ports based on the one or more first CSI measurements and the one or more CSI spatial prediction parameters (940). For example, the first subset may be smaller than the plurality of antenna ports.

[0311] According to an embodiment, the WTRU 102 may be configured to send information indicating the first subset of antenna ports and / or one or more parameters associated with the first subset of antenna ports to a network node (950).

[0312] According to an embodiment, the WTRU 102 may be configured to receive a second plurality of reference signals transmitted from the first subset of antenna ports (960).

[0313] According to an embodiment, the WTRU 102 may be configured to perform / estimate one or more second CSI measurements based on a second plurality of reference signals (970).

[0314] According to an embodiment, the WTRU 102 may be configured to predict one or more third CSI measurements for a second subset of antenna ports of a plurality of antenna ports of a network node, for example based on the estimated one or more second CSI measurements.

[0315] According to an embodiment, the WTRU 102 may be configured to send CSI feedback information including CSI measurements of any of: (1) a first subset of antenna ports, (2) a second subset of antenna ports, and (3) multiple antenna ports.

[0316] According to an embodiment, the WTRU 102 may be configured to send CSI feedback information indicating any of: (1) a first CSI measurement, (2) a second CSI measurement, and (3) a third CSI measurement.

[0317] According to an embodiment, one or more CSI spatial prediction parameters may include any of the following: (1) a maximum number of antenna ports for a first antenna port subset, for example, for determining the first antenna port subset; (2) a method for determining the first antenna port subset; and (3) a measure of spatial correlation between the first antenna port subset and the second antenna port subset.

[0318] According to an embodiment, the second subset of antenna ports may be complementary to the first subset of antenna ports.

[0319] According to an embodiment, the WTRU 102 may be configured to use an artificial intelligence / machine learning model to predict one or more third CSI measurements for the second antenna port subset.

[0320] According to an embodiment, the one or more parameters associated with the first subset of antenna ports may include one or more channel coefficients associated with the first subset of antenna ports.

[0321] According to an embodiment, the WTRU 102 configured to determine the first subset of antenna ports may include the WTRU 102 configured to determine the first subset of antenna ports based on satisfying a threshold value between one or more channel coefficients associated with the first subset of antenna ports.

[0322] According to an embodiment, one or more channel coefficients associated with the first antenna port subset may be one or more first channel coefficients associated with the first antenna port subset, and the WTRU 102 may be configured to predict one or more second channel coefficients associated with the second antenna port subset based on the one or more first channel coefficients associated with the first antenna port subset.

[0323] According to an embodiment, the WTRU 102 may be configured to send information indicative of one or more second channel coefficients associated with the second subset of antenna ports to a network node.

[0324] According to an embodiment, the WTRU 102 may be configured to determine a condition indicating one or more changes in one or more channel conditions associated with a first subset of antenna ports, wherein the condition may be based on estimating one or more fifth CSI measurements based on a third plurality of reference signals transmitted from the first subset of antenna ports; and in response to such a determination, the WTRU 102 may be configured to change the first subset of antenna ports.

[0325] According to an embodiment, the condition may include a data block / transfer error rate exceeding a threshold.

[0326] in conclusion

[0327] The system and method for processing data according to a representative embodiment can be executed by one or more processors that execute a sequence of instructions contained in a memory device. Such instructions can be read from other computer-readable media such as auxiliary data storage devices into the memory device. The execution of the sequence of instructions contained in the memory device causes the processor to operate, for example, as described above. In an alternative embodiment, hard-wired circuits can replace software instructions or be used in combination with software instructions to implement the present invention. Such software can be run on a processor contained in a robot assistant / equipment (RAA) and / or remotely contained in another mobile device. In the latter case, data can be transmitted between the RAA or other mobile devices containing sensors and a remote device containing a processor via wire or wirelessly, and the processor runs software that performs scale estimation and compensation as described above. According to other representative embodiments, some of the processing described above with respect to positioning can be performed in a device containing a sensor / camera, and the remaining processing can be performed in a second device after receiving partially processed data from a device containing a sensor / camera.

[0328] Although features and elements are provided above in specific combinations, it will be understood by those skilled in the art that each feature or element can be used alone or in any combination with other features and elements. The present disclosure is not limited in terms of the specific embodiments described in the present application, which are intended to be illustrations of various aspects. Without departing from its spirit and scope, many modifications and changes can be made, as will be apparent to those skilled in the art. Any element, action or instruction used in the description of the present application should not be interpreted as being critical or necessary to the present invention unless explicitly provided as such. In addition to those listed herein, functionally equivalent methods and devices within the scope of the present disclosure are apparent to those skilled in the art from the foregoing description. Such modifications and changes are intended to fall within the scope of the appended claims. The present disclosure is limited only by the terms of the appended claims and the full scope of equivalents given by such claims. It should be understood that the present disclosure is not limited to specific methods or systems herein.

[0329] For simplicity, the foregoing embodiments are discussed with respect to terminology and structure of devices with infrared capabilities (i.e., infrared transmitters and receivers). However, the embodiments discussed are not limited to these systems, but can be applied to other systems using other forms of electromagnetic waves or non-electromagnetic waves (such as sound waves).

[0330] It will also be understood that the terms used herein are used only for the purpose of describing specific embodiments and are not intended to be limiting. As used herein, the term "video" or the term "image" may mean any of a snapshot, a single image, and / or a plurality of images displayed over a certain time basis. As another example, when referred to herein, the term "user equipment" and its abbreviation "UE", the term "remote" and / or the term "head-mounted display" or its abbreviation "HMD" may mean or include (i) a wireless transmit and / or receive unit (WTRU); (ii) any of many embodiments of a WTRU; (iii) a device with wireless capabilities and / or wired capabilities (e.g., wearable) that is configured with some or all of the structure and functionality of a WTRU; (iii) a device with wireless capabilities and / or wired capabilities that is configured with less than all of the structure and functionality of a WTRU; or (iv) a similar device. References herein to Figures 1A to 1D Details of an example WTRU are provided, which may be representative of any WTRU set forth herein. As another example, various disclosed embodiments herein are described above and below as utilizing a head mounted display. Those skilled in the art will recognize that devices other than a head mounted display may be utilized, and some or all of the present disclosure and various disclosed embodiments may be modified accordingly without undue experimentation. Examples of such other devices may include drones or other devices configured to stream information to provide an adapted reality experience.

[0331] In addition, the methods provided herein can be implemented in a computer program, software or firmware that is incorporated into a computer-readable medium for execution by a computer or processor. Examples of computer-readable media include electronic signals (transmitted via a wired or wireless connection) and computer-readable storage media. Examples of non-temporary computer-readable storage media include, but are not limited to, read-only memory (ROM), random access memory (RAM), registers, 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 associated with software can be used to implement a radio frequency transceiver for a WTRU, UE, terminal, base station, RNC, MME, EPC, AMF or any host computer.

[0332] Variations of the methods, devices, and systems provided above are possible without departing from the scope of the present invention. In view of the various embodiments that may be applied, it should be understood that the embodiments shown are merely examples and should not be considered to limit the scope of the appended claims. For example, the embodiments provided herein include handheld devices that may include or be used with any suitable voltage source (such as a battery, etc.) that provides any suitable voltage.

[0333] In addition, in the embodiments provided above, processing platforms, computing systems, controllers, and other devices including processors are mentioned. These devices may include at least one central processing unit ("CPU") and memory. According to the practice of those skilled in the art of computer programming, references to actions and symbolic representations of operations or instructions may be performed by various CPUs and memories. Such actions and operations or instructions may be referred to as "execution," "computer execution," or "CPU execution."

[0334] Those of ordinary skill in the art will appreciate that the actions and symbolic representations of operations or instructions include manipulation of electrical signals by the CPU. The electrical system represents data bits, which may cause the final conversion or reduction of electrical signals and maintain the data bits in memory locations in the storage system, thereby reconfiguring or otherwise changing the operation of the CPU and other processing of signals. The memory locations where the data bits are maintained are physical locations having specific electrical, magnetic, optical, or organic properties that correspond to or represent the data bits. It should be understood that the embodiments are not limited to the above-mentioned platforms or CPUs, and other platforms and CPUs may support the provided methods.

[0335] The data bits may also be maintained on a computer-readable medium, including a magnetic disk, an optical disk, and any other volatile (e.g., random access memory (RAM)) or non-volatile (e.g., read-only memory (ROM)) mass storage system readable by a CPU. The computer-readable medium may include cooperating or interconnected computer-readable media that reside only on a processing system or 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 other platforms and memories may support the provided methods.

[0336] In an illustrative embodiment, any 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.

[0337] There is little difference between hardware and software implementations of various aspects of the system. The use of hardware or software is usually (but not always, as in some cases, the choice of hardware or software may become important) a design choice that represents a cost-efficiency trade-off. There may be various vehicles (e.g., hardware, software, and / or firmware) with which the processes and / or systems and / or other technologies described herein can be implemented, and the preferred vehicle may change with the context in which the processes and / or systems and / or other technologies are deployed. For example, if the implementer determines that speed and accuracy are most important, then the implementer may select a primary hardware and / or firmware vehicle. If flexibility is most important, then the implementer may select a primary software implementation. Alternatively, the implementer may select some combination of hardware, software, and / or firmware.

[0338] The foregoing detailed description has been described various embodiments of the apparatus and / or process by using block diagrams, flow charts and / or examples. Insofar as such block diagrams, flow charts and / or examples include one or more functions and / or operations, it will be understood by those skilled in the art that each function and / or operation within such block diagrams, flow charts or examples can be implemented individually and / or collectively by a wide range of hardware, software, firmware or indeed any combination thereof. In an embodiment, several parts of the subject matter described herein may be implemented via an application specific integrated circuit (ASIC), a field programmable gate array (FPGA), a digital signal processor (DSP) and / or other integrated formats. However, those skilled in the art will recognize that all or part of some aspects of the embodiments disclosed herein may be equivalently implemented in an integrated circuit, 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 almost as any combination thereof, and according to the present disclosure, designing circuit systems and / or writing codes for software and / or firmware will be completely within the skill range of those skilled in the art. In addition, those skilled in the art will appreciate that the mechanisms of the subject matter described herein can be distributed as a program product in a variety of forms, and that the illustrative examples of the subject matter described herein apply regardless of the particular type of signal-bearing medium used to actually carry out the distribution. Examples of signal-bearing media include, but are not limited to, the following: recordable media such as floppy disks, hard drives, CDs, DVDs, digital tapes, computer memory, etc.; and transmission media such as digital and / or analog communication media (e.g., fiber optic cables, waveguides, wired communication links, wireless communication links, etc.).

[0339] Those skilled in the art will recognize that it is common in the art to describe devices and / or processes in the manner 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 can be integrated into a data processing system by a reasonable amount of experimentation. Those skilled in the art will recognize that a typical data processing system can typically include a system unit housing, a video display device, a memory such as volatile and non-volatile memory, a processor such as a microprocessor and a digital signal processor, a computing entity such as an operating system, a driver, a graphical user interface, and an application, one or more interactive devices such as a touch pad or screen, and / or a control system including a feedback loop and a control motor (e.g., feedback for sensing position and / or velocity; a control motor for moving and / or adjusting components and / or quantities). A typical data processing system can be implemented using any suitable commercially available components, such as components typically found in data computing / communication and / or network computing / communication systems.

[0340] The subject matter described herein sometimes illustrates different parts that are included in different other parts or connected with different other parts.It should be understood that the architecture of such description is only an example, and many other architectures that realize the same function can actually be implemented.In a conceptual sense, any arrangement of parts for realizing the same function is effectively "associated" so that the desired function can be realized.Therefore, any two parts that are combined to realize a specific function in this article can be regarded as "associated" with each other so that no matter how the architecture or intermediate parts realize the desired function.Similarly, any two parts that are associated in this way can also be regarded as "operably connected" or "operably coupled" to realize the desired function, and any two parts that can be associated in this way can also be regarded as "operably coupled" to realize the desired function.The specific example of operable coupling includes (but is not limited to) parts that can be matched physically and / or physically interact, and / or parts that can be wirelessly interacted and / or wirelessly interacted, and / or parts that can be logically interacted and / or parts that can be logically interacted.

[0341] With respect to the use of substantially any plural and / or singular terms herein, those skilled in the art can translate from the plural to the singular and / or from the singular to the plural where appropriate to the context and / or application. For clarity, the various singular / plural arrangements may be expressly set forth herein.

[0342] Those skilled in the art will understand that, in general, the terms used herein and particularly in the appended claims (e.g., the bodies of the appended claims) are generally intended to be "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 "including but not limited to," etc.). Those skilled in the art will further understand that if a specific number of an introduced claim statement is intended, such intent will be expressly stated in the claim, and in the absence of such a statement, such intent is not present. For example, where only one item is intended, the term "single" or similar language may be used. To aid understanding, the following appended claims and / or the description herein may include the use of the introductory phrases "at least one" and "one or more" to introduce multiple claim statements. However, the use of such phrases should not be interpreted as implying that a claim recitation introduced by the indefinite article "a" or "an" will limit any particular claim including such introduced claim recitation to embodiments including only one such recitation, even if the same claim includes the introductory phrases "one or more" or "at least one" and an indefinite article such as "a" or "an" (e.g., "a" and / or "an" should be interpreted as meaning "at least one" or "one or more"). The same is true for the use of definite articles to introduce claim recitations. In addition, even if a specific number of introduced claim recitations is explicitly recited, one skilled in the art will recognize that such recitation should be interpreted as meaning at least the recited number (e.g., merely reciting "two recitations" without other modifiers means at least two recitations or two or more recitations). Furthermore, in those cases where a convention similar to “at least one of A, B, and C, etc.” is used, generally, such construction is intended to represent the convention that one skilled in the art would understand (e.g., “a system having at least one of A, B, and C” would include, but is not limited to, systems having only A, only B, only C, both A and B, both A and C, both B and C, and / or both A, B, and C, etc.). In those cases where a convention similar to “at least one of A, B, or C, etc.” is used, generally, such meaning is intended in the sense that one skilled in the art would understand the convention (e.g., “a system having at least one of A, B, or C” would include, but is not limited to, systems having only A, only B, only C, both A and B, both A and C, both B and C, and / or both A, B, and C, etc.). One skilled in the art would further understand that any transitional words and / or phrases (whether in the specification, claims, or drawings) that actually give two or more alternatives should be understood to contemplate the possibility of including one of the items, either of the items, or both of the items.For example, the phrase "A or B" will be understood to include the possibility of "A" or "B" or "A and B." In addition, the term "any" as used herein followed by a list of multiple items and / or categories of items is intended to include "any," "any combination," "any multiple," and / or "any combination of multiples," either alone or in combination with other items and / or other categories of items. Furthermore, the term "set," as used herein, is intended to include any number of items, including zero. Additionally, the term "number," as used herein, is intended to include any number, including zero. And the term "plurality," as used herein, is intended to be synonymous with "multiple."

[0343] 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.

[0344] As will be understood by those skilled in the art, for any and all purposes, such as in providing a written description, all ranges disclosed herein also encompass any and all possible sub-ranges and combinations of sub-ranges thereof. Any listed range can be easily identified as fully describing and capable of decomposing the same range into at least equal halves, one-third, one-quarter, one-fifth, one-tenth, etc. As a non-limiting example, each range discussed herein can be easily decomposed into a lower third, a middle third, and an upper third, etc. As will be understood by those skilled in the art, all languages ​​such as "at most", "at least", "greater than", "less than", etc. include the enumerated numbers, and refer to the ranges that can be subsequently subdivided into sub-ranges as discussed above. Finally, as will be understood by those skilled in the art, the range includes each individual member. Therefore, for example, a group with 1 to 3 units refers to a group with 1, 2 or 3 units. Similarly, a group with 1 to 5 units refers to a group with 1, 2, 3, 4 or 5 units, and so on.

[0345] Furthermore, the claims should not be read as limited to the order or elements provided unless otherwise stated. In addition, the use of the term "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 term "means for..." is not intended to be so.

[0346] By way of example, suitable processors include 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, an application specific integrated circuit (ASIC), an application specific standard product (ASSP); a field programmable gate array (FPGA) circuit, any other type of integrated circuit (IC), and / or state machine.

[0347] The WTRU may be used in conjunction with modules implemented in hardware and / or software, including software defined radio (SDR), and other components such as cameras, video camera modules, video phones, speaker phones, vibrating devices, speakers, microphones, television transceivers, hands-free headsets, keyboards, module, a frequency modulation (FM) radio unit, a near field communication (NFC) module, a liquid crystal display (LCD) display unit, an organic light emitting diode (OLED) display unit, a digital music player, a media player, a video game console module, an internet browser, and / or any wireless local area network (WLAN) or ultra-wideband (UWB) module.

[0348] Although various embodiments have been described in terms of a communication system, it is contemplated that the system may be implemented in software on a microprocessor / general purpose computer (not shown). In certain embodiments, one or more functions of the various components may be implemented in software controlling a general purpose computer.

[0349] Furthermore, while the invention has been shown and described herein with reference to particular embodiments, the invention is not intended to be limited to the details shown. Rather, various modifications may be made in the details within the range and range of equivalents of the claims and without departing from the invention.

Claims

1. A method implemented in a wireless transmit receive unit (WTRU), the method include: receiving configuration information indicating one or more channel state information (CSI) spatial prediction parameters from a network node; receiving a first plurality of reference signals transmitted from a plurality of antenna ports of the network node; estimating one or more first CSI measurements based on the plurality of received reference signals; determining a first subset of antenna ports of the plurality of antenna ports of the network node and one or more parameters associated with the first subset of antenna ports based on the one or more first CSI measurements and the one or more CSI spatial prediction parameters, wherein the first subset is smaller than the plurality of antenna ports; sending information indicating the first subset of antenna ports and the one or more parameters associated with the first subset of antenna ports to the network node; receiving a second plurality of reference signals transmitted from the first subset of antenna ports; as well as One or more second CSI measurements are estimated based on the second plurality of reference signals.

2. The method according to claim 1, wherein include: predicting one or more third CSI measurements for a second subset of the plurality of antenna ports of the network node based on the estimated one or more second CSI measurements; and CSI feedback information is sent, the CSI feedback information indicating any of: (1) the one or more first CSI measurements; (2) the one or more second CSI measurements; and (3) the one or more third CSI measurements.

3. The method according to claim 2, in, The one or more CSI spatial prediction parameters include any of the following: (1) a maximum number of antenna ports of the first antenna port subset; (2) a method for determining the first antenna port subset; and (3) a measure of spatial correlation between the first subset of antenna ports and the second subset of antenna ports.

4. The method according to any one of claims 2 to 3, in, The second antenna port subset is complementary to the first antenna port subset.

5. The method according to any one of claims 2 to 4, wherein the method include: An artificial intelligence / machine learning model is used to predict the one or more third CSI measurements for the second subset of antenna ports.

6. The method according to any one of claims 2 to 5, in, The one or more parameters associated with the first subset of antenna ports include one or more channel coefficients associated with the first subset of antenna ports.

7. The method according to claim 6, in, Determining a first subset of antenna ports includes determining the first subset of antenna ports based on satisfying a threshold value of a minimum correlation between the one or more channel coefficients associated with the first subset of antenna ports.

8. The method according to any one of claims 6 to 7, in, The one or more parameters associated with the first subset of antenna ports are one or more channel coefficients associated with the first subset of antenna ports, the method comprising: predicting one or more second channel coefficients associated with the second subset of antenna ports based on the one or more first channel coefficients associated with the first subset of antenna ports; and Information indicative of the one or more second channel coefficients associated with the second subset of antenna ports is sent to the network node.

9. The method according to any one of claims 2 to 8, wherein the method include: determining conditions indicative of one or more changes in one or more channel conditions associated with the first subset of antenna ports, wherein the conditions are based on estimating one or more fifth CSI measurements based on a third plurality of reference signals transmitted from the first subset of antenna ports; as well as In response to the determination, the first subset of antenna ports is altered.

10. The method according to claim 9, in, The condition includes a data block error rate exceeding a threshold.

11. A wireless transmit / receive unit (WTRU) comprising a circuit system including a transmitter, a receiver, a processor, and a memory, the WTRU being configured to: receiving configuration information indicating one or more channel state information (CSI) spatial prediction parameters from a network node; receiving a first plurality of reference signals transmitted from a plurality of antenna ports of the network node; estimating one or more first CSI measurements based on the plurality of received reference signals; determining a first subset of antenna ports of the plurality of antenna ports of the network node and one or more parameters associated with the first subset of antenna ports based on the one or more first CSI measurements and the one or more CSI spatial prediction parameters, wherein the first subset is smaller than the plurality of antenna ports; sending information indicating the first subset of antenna ports and the one or more parameters associated with the first subset of antenna ports to the network node; receiving a second plurality of reference signals transmitted from the first subset of antenna ports; as well as One or more second CSI measurements are estimated based on the second plurality of reference signals.

12. The WTRU of claim 11 , wherein the WTRU is configured to: predicting one or more third CSI measurements for a second subset of the plurality of antenna ports of the network node based on the estimated one or more second CSI measurements; and CSI feedback information is sent, the CSI feedback information indicating any of: (1) the one or more first CSI measurements; (2) the one or more second CSI measurements; and (3) the one or more third CSI measurements.

13. The WTRU of claim 12, in, The one or more CSI spatial prediction parameters include any of the following: (1) a maximum number of antenna ports of the first antenna port subset; (2) a method for determining the first antenna port subset; and (3) a measure of spatial correlation between the first subset of antenna ports and the second subset of antenna ports.

14. The WTRU according to any one of claims 12 to 13, in, The second antenna port subset is complementary to the first antenna port subset.

15. The WTRU of any one of claims 12 to 14, wherein the WTRU is configured to use an artificial intelligence / machine learning model to predict the one or more third CSI measurements for the second subset of antenna ports.

16. The WTRU according to any one of claims 12 to 15, in, The one or more parameters associated with the first subset of antenna ports include one or more channel coefficients associated with the first subset of antenna ports.

17. The WTRU of claim 16, in, The WTRU configured to determine a first subset of antenna ports includes the WTRU configured to determine the first subset of antenna ports based on satisfying a threshold value for a minimum correlation between the one or more channel coefficients associated with the first subset of antenna ports.

18. The WTRU according to any one of claims 16 to 17, in, The one or more parameters associated with the first subset of antenna ports are one or more channel coefficients associated with the first subset of antenna ports, wherein the WTRU is configured to: predicting one or more second channel coefficients associated with the second subset of antenna ports based on the one or more first channel coefficients associated with the first subset of antenna ports; as well as Information indicative of the one or more second channel coefficients associated with the second subset of antenna ports is sent to the network node.

19. The WTRU according to any one of claims 12 to 18, wherein the WTRU is configured to: determining conditions indicative of one or more changes in one or more channel conditions associated with the first subset of antenna ports, wherein the conditions are based on estimating one or more fifth CSI measurements based on a third plurality of reference signals transmitted from the first subset of antenna ports; and In response to the determination, the first subset of antenna ports is altered.

20. The WTRU of claim 19, in, The condition includes a data block error rate exceeding a threshold.

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