Beam management and beam inference

Abstract

Systems, methods, and tools associated with beam management and beam inference (e.g., for holographic MIMO) are described herein. A wireless transmit / receive unit (WTRU) may receive configuration information from a network device, where the configuration information may indicate a hierarchical spatial arrangement of at least a first plurality of beams and a second plurality of beams. The WTRU may also be configured to perform a measurement of beams belonging to the first plurality of beams or the second plurality of beams, transmit a report regarding the measurement of the beams to the network device, and determine a transmit beam to be used by the WTRU based on the configuration information and a beam indication received from the network device after the report is transmitted. The WTRU may then perform the transmission using the transmit beam.

Description

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims the benefit of U.S. Provisional Patent Application No. 63 / 394,005, filed on August 1, 2022, the disclosure of which is incorporated herein by reference in its entirety. Background Art

[0003] The wireless communication system may be configured to use multiple-input multiple-output (MIMO) technology to transmit and receive information in the wireless communication system. Multiple antenna ports, precoding schemes, and / or CSI feedback mechanisms may be used to facilitate MIMO transmission and reception. Beam management procedures may be implemented to improve beam quality and reduce beam interference. Summary of the invention

[0004] Systems, methods, and tools associated with beam management and / or beam inference are described herein. A wireless transmit / receive unit (WTRU) as described herein may include a processor that may be configured to receive configuration information from a network device, wherein the configuration information may indicate a hierarchical spatial arrangement of at least a first plurality of beams and a second plurality of beams, the first plurality of beams may be associated with a first spatial resolution, the second plurality of beams may be associated with a second spatial resolution, and an area covered by one of the first plurality of beams may include an area covered by one of the second plurality of beams. The WTRU may also be configured to perform measurements of beams belonging to the first plurality of beams or the second plurality of beams, send a report on the measurements of the beams to the network device, and determine a transmit beam to be used by the WTRU based on the configuration information and a beam indication received from the network device after the report is sent. The WTRU may then perform a transmission using the transmit beam.

[0005] In an example, the beam measured by the WTRU may be one of the first plurality of beams, and the transmit beam may be one of the second plurality of beams. In an example, the WTRU may also be configured to make a prediction regarding the transmit beam based on configuration information received from the network device and measurements performed by the WTRU, and send an indication of the prediction to the network device. For example, the prediction made by the WTRU may be that the transmit beam to be used by the WTRU is narrower than the beam measured by the WTRU, and the WTRU may be configured to include an indication of the prediction in a report sent to the network device.

[0006] In an example, the configuration information may include a first codebook associated with a first plurality of beams and a second codebook associated with a second plurality of beams, and the beam indication received from the network device may include an index that may identify a transmit beam in the first codebook or the second codebook. In an example, the configuration information may also indicate a first channel state information reference signal (CSI-RS) resource set associated with the first plurality of beams and a second CSI-RS resource set associated with the second plurality of beams, and measurements of the beams may be performed using CSI-RS resources from the first CSI-RS resource set or the second CSI-RS resource set. In an example, the WTRU may also be configured to predict a receive beam based at least on the configuration information received from the network device, and include an indication of the predicted receive beam in a report sent to the network device. The WTRU may indicate the predicted receive beam, for example, via a codeword index associated with the codebook (e.g., the codebook may be included in the configuration information received from the network device and may be associated with the first plurality of beams or the second plurality of beams). BRIEF DESCRIPTION OF THE DRAWINGS

[0007] Figure 1A is a system diagram illustrating an example communication system in which one or more disclosed embodiments may be implemented.

[0008] Figure 1B is an example of a method that can be used according to an embodiment of the present invention. Figure 1A A system diagram of an example wireless transmit / receive unit (WTRU) for use within an illustrated communication system.

[0009] Figure 1C is an example of a method that can be used according to an embodiment of the present invention. Figure 1A System diagram of an example Radio Access Network (RAN) and an example Core Network (CN) for use within the illustrated communication system.

[0010] Figure 1D is an example of a method that can be used according to an embodiment of the present invention. Figure 1A System diagram of another example RAN and another example CN for use within the illustrated communication system.

[0011] Figure 2 is a diagram illustrating an example of a hybrid beamforming architecture and antenna ports.

[0012] Figure 3 is a diagram illustrating an example of supported antenna port configurations.

[0013] Figure 4 is a diagram illustrating an example of a rotated orthogonal beam and an orthogonal discrete Fourier transform (DFT) beam.

[0014] Figure 5 is a diagram illustrating an example of a beam management phase.

[0015] Figure 6 is a diagram illustrating an example of spatial domain beam inference based on measurements of a set of wide beams.

[0016] Figure 7 is a diagram illustrating an example of spatial domain beam inference based on measurements of a set of narrow beams.

[0017] Figure 8 is a diagram illustrating an example of a holographic MIMO architecture.

[0018] Figure 9(a) to Figure 9(e) is a diagram illustrating an example of hierarchical beam design.

[0019] Fig.10 is a diagram illustrating an example of a beam at level k and its sub-beams.

[0020] Fig.11 is a diagram illustrating an example of an SSB beam associated with a low-level hierarchical beam in a hierarchical beam structure.

[0021] Fig.12 is a diagram illustrating an example of beam management and beam inference associated with H-MIMO.

[0022] Fig.13 is a flow chart illustrating an example of beam inference (e.g., when the WTRU is in a radio resource control (RRC) connected state).

[0023] Fig.14 is a diagram illustrating an example of beam management (eg, during an initial access phase).

[0024] Fig.15 is a diagram illustrating an example of random access opportunity configuration associated with beam inference.

[0025] Fig.16 is a flow chart illustrating an example of beam inference at a WTRU (eg, when the WTRU is in an RRC connected state).

[0026] Fig.17 is a diagram illustrating an example of beam management and beam inference associated with H-MIMO.

[0027] Fig.18 is a diagram illustrating an example of a hierarchical beam structure or arrangement that may be configured for a WTRU.

[0028] Fig.19 is a flow diagram illustrating example operations that may be associated with beam management and / or beam inference. DETAILED DESCRIPTION

[0029] 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 through sharing of system resources (including wireless bandwidth). 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, and filter bank multi-carrier (FBMC), etc.

[0030] like Figure 1A As 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 should be understood 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 send and / or receive wireless signals and may include a user equipment (WTRU), 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 an industrial and / or automated process chain environment), a consumer electronic device, a device operating on a commercial and / or industrial wireless network, etc. Any of the WTRUs 102a, 102b, 102c, and 102d may be interchangeably referred to as a WTRU.

[0031] The communication system 100 may also include a base station 114a and / or a base station 114b. Each of the base stations 114a, 114b may be any type of device that is 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 evolved Node B (eNB), a Home Node B, a Home evolved Node B, a next generation Node B (gNB), an NR Node B, a site controller, an access point (AP), a wireless router, and the like. Although the base stations 114a, 114b are each depicted as a single element, it should be appreciated that the base stations 114a, 114b may include any number of interconnected base stations and / or network elements.

[0032] Base station 114a may be part of RAN 104 / 113, which may also include other base stations and / or network elements (not shown), such as base station controllers (BSC), radio network controllers (RNC), relay nodes, etc. Base station 114a and / or base station 114b may be configured to send 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, which may be relatively fixed or may change over time. The cell may be further divided into cell sectors. For example, the cell associated with base station 114a may be divided into three sectors. Therefore, in one embodiment, base station 114a may include three transceivers, i.e., one transceiver for each sector of the cell. In an embodiment, base station 114a may employ multiple-input multiple-output (MIMO) technology and may utilize multiple transceivers for each sector of the cell. For example, beamforming may be used to send and / or receive signals in a desired spatial direction.

[0033] 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).

[0034] More specifically, as noted 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, and SC-FDMA. 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 115 / 116 / 117. WCDMA may include communication protocols such as High Speed ​​Packet Access (HSPA) and / or Evolved HSPA (HSPA+). HSPA may include High Speed ​​Downlink (DL) Packet Access (HSDPA) and / or High Speed ​​UL Packet Access (HSUPA).

[0035] 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) that may establish the air interface 116 using Long Term Evolution (LTE) and / or Advanced LTE (LTE-A) and / or Advanced LTE Pro (LTE-A Pro).

[0036] In an embodiment, the base station 114a and the WTRUs 102a, 102b, 102c may implement a radio technology such as NR radio access, which may establish the air interface 116 using New Radio (NR).

[0037] 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 together implement LTE radio access and NR radio access, for example using the dual connectivity (DC) principle. Thus, the air interface utilized by the WTRUs 102a, 102b, 102c may be characterized by multiple types of radio access technologies and / or transmissions transmitted to / from multiple types of base stations (e.g., eNBs and gNBs).

[0038] In other embodiments, the base station 114a and the WTRUs 102a, 102b, 102c may implement radio technologies 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), and GSM EDGE (GERAN).

[0039] Figure 1A The base station 114b in may be, for example, a wireless router, a Home NodeB, a Home eNodeB, or an access point, and may utilize any suitable RAT to facilitate wireless connectivity in local areas such as commercial venues, homes, vehicles, campuses, industrial facilities, sky corridors (e.g., for use by drones), and roads. 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 yet 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 picocell or a femtocell. As Figure 1A As shown, base station 114b may have a direct connection to Internet 110. Therefore, base station 114b may not need to access Internet 110 via CN 106 / 115.

[0040] 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, error 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 calling, Internet connectivity, video distribution, etc., and / or perform high-level security functions, such as user authentication. Although not described in detail in the text and video, the CN 106 / 115 may be 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, error 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 calling, Internet connectivity, video distribution, etc., and / or perform high-level security functions, such as user authentication. Figure 1AAlthough not shown in the figure, it will be appreciated that the RAN 104 / 113 and / or the CN 106 / 115 may be in direct or indirect communication with other RANs that employ the same RAT as the RAN 104 / 113 or a different RAT. For example, in addition to being connected to the RAN 104 / 113, which may utilize 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.

[0041] The CN 106 / 115 may also act 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 communication networks 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 employ the same RAT as the RAN 104 / 113 or a different RAT.

[0042] 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.

[0043] 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.

[0044] 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) and state machine, etc. The processor 118 may perform signal decoding, 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 is understood that the processor 118 and the transceiver 120 may be integrated together in an electronic package or chip.

[0045] The send / receive element 122 may be configured to send a signal to a base station (e.g., base station 114a) or receive a signal from a base station via an air interface 116. For example, in one embodiment, the send / receive element 122 may be an antenna configured to send and / or receive an RF signal. In an embodiment, the send / receive element 122 may be a transmitter / detector configured to send and / or receive, for example, an IR, UV, or visible light signal. In another embodiment, the send / receive element 122 may be configured to send and / or receive both an RF signal and an optical signal. It should be understood that the send / receive element 122 may be configured to send and / or receive any combination of wireless signals.

[0046] Although the transmit / receive element 122 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.

[0047] 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 noted above, the WTRU 102 may have multi-mode capabilities. For example, the transceiver 120 may include multiple transceivers for enabling the WTRU 102 to communicate via multiple RATs, such as NR and IEEE 802.11.

[0048] 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, and a secure digital (SD) memory card, among others. 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).

[0049] The processor 118 may receive power from the power source 134, and may be configured to distribute and / or control power to the other components in the WTRU 102. The power source 134 may be any suitable device for powering the WTRU 102. For example, the power source 134 may include one or more dry cell batteries (e.g., nickel cadmium (NiCd), nickel zinc (NiZn), nickel metal hydride (NiMH), lithium ion (Li-ion), etc.), solar cells, fuel cells, etc.

[0050] 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 signals received 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.

[0051] The processor 118 may also be coupled to other peripherals 138, which may include one or more software modules 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, FM radio unit, digital music player, media player, video game player module, Internet browser, virtual reality and / or augmented reality (VR / AR) device and activity tracker, etc. Peripheral device 138 may include one or more sensors, which may be one or more of the following: gyroscope, accelerometer, Hall effect sensor, magnetometer, orientation sensor, proximity sensor, temperature sensor, time sensor; geolocation sensor; altimeter, light sensor, touch sensor, magnetometer, barometer, gesture sensor, biometric sensor and / or humidity sensor.

[0052] The WTRU 102 may include a full-duplex radio for which transmission and reception of some or all signals (e.g., associated with specific subframes for both UL (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 for reducing and / or substantially eliminating self-interference via hardware (e.g., a choke) or via signal processing performed by a processor (e.g., a separate processor (not shown) or via the processor 118). In one embodiment, the WRTU 102 may include a half-duplex radio for which transmission and reception of some or all signals (e.g., associated with specific subframes for both UL (e.g., for transmission) or downlink (e.g., for reception)) may be concurrent and / or simultaneous.

[0053] Figure 1C 1 is a system diagram illustrating the RAN 104 and the CN 106 in accordance with an embodiment. As noted 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.

[0054] The RAN 104 may include evolved Node-Bs 160a, 160b, 160c, though it will be appreciated that the RAN 104 may include any number of evolved Node-Bs while remaining consistent with an embodiment. The evolved Node-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 evolved Node-Bs 160a, 160b, 160c may implement MIMO technology. Thus, the evolved Node-B 160a, for example, may use multiple antennas to transmit wireless signals to and / or receive wireless signals from the WTRU 102a.

[0055] Each of the evolved Node 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, and scheduling of users in the UL and / or DL, among other things. Figure 1C As shown, the eNode-Bs 160a, 160b, 160c may communicate with one another via an X2 interface.

[0056] 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 are depicted as being part of the CN 106, it should be understood that any of these elements may be owned and / or operated by an entity other than a CN operator.

[0057] The MME 162 may be connected to each of the evolved Node-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, and selecting a particular serving gateway during an initial attach of the WTRUs 102a, 102b, 102c. 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.

[0058] The SGW 164 may be connected to each of the evolved Node-Bs 160a, 160b, 160c in the RAN 104 via an S1 interface. The SGW 164 may generally route and forward user data packets to / from the WTRUs 102a, 102b, 102c. The SGW 164 may perform other functions, such as anchoring the user plane during an inter-evolved Node-B handover, triggering paging when DL data is available for the WTRUs 102a, 102b, 102c, and managing and storing the context of the WTRUs 102a, 102b, 102c.

[0059] 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.

[0060] 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 be in communication with, an IP gateway (e.g., an IP Multimedia Subsystem (IMS) server) that acts 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 networks and / or wireless networks owned and / or operated by other service providers.

[0061] Although the WTRU Figures 1A to 1D Although described as wireless terminals, it is contemplated that in certain representative embodiments, such terminals may (eg, temporarily or permanently) use a wired communications interface with a communications network.

[0062] In a representative embodiment, the other network 112 may be a WLAN.

[0063] A WLAN in infrastructure basic service set (BSS) mode may have an access point (AP) for a BSS and one or more stations (STAs) associated with the AP. The AP may have access or an interface to a distribution system (DS) or another type of wired / wireless network that carries traffic to and / or out of the BSS. Traffic originating from outside the BSS and destined for the STA may be reached by the AP and may be delivered to the STA. Traffic originating from the STA and destined for a target outside the BSS may be transmitted to the AP to be delivered to the corresponding target. Traffic between STAs within the BSS may be transmitted by the AP, for example, wherein the source STA may transmit traffic to the AP, and the AP may deliver traffic to the target 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 transmitted between the source STA and the target STA (e.g., directly between them) using a direct link setup (DLS). 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 within or using the IBSS (eg, all STAs in the STA) may communicate directly with each other. The IBSS communication mode may sometimes be referred to herein as an "ad hoc" communication mode.

[0064] When using the 802.11ac infrastructure operation mode or a similar operation mode, the AP may send beacons on a fixed channel (such as a primary channel). The primary channel may be a fixed width (e.g., a 20 MHz wide bandwidth) or a width dynamically set via signaling. The primary channel may be an operating channel of the BSS and may be used by the STA to establish a connection with the AP. In certain representative embodiments, carrier sense multiple access / collision avoidance (CSMA / CA) may be implemented, for example, in an 802.11 system. For CSMA / CA, a STA (e.g., each STA) (including the AP) may sense the primary channel. If the primary channel is sensed / detected and / or determined to be busy by a particular STA, the particular STA may back off. One STA (e.g., only one station) may transmit at any given time in a given BSS.

[0065] High throughput (HT) STAs may communicate using a 40 MHz wide channel (eg, via a combination of a primary 20 MHz channel and adjacent or non-adjacent 20 MHz channels) to form a 40 MHz wide channel.

[0066] Very high throughput (VHT) STA can support 20MHz, 40MHz, 80MHz and / or 160MHz wide channels. 40MHz channels and / or 80MHz channels can be formed by combining continuous 20MHz channels. 160MHz channels can be formed by combining 8 continuous 20MHz channels, or by combining two non-continuous 80MHz channels (this can be called 80+80 configuration). For 80+80 configuration, after channel coding, the data can pass through a segment parser that can divide the data into two streams. Each stream can be processed by inverse fast Fourier transform (IFFT) and time domain processing separately. These streams can be mapped to two 80MHz channels, and the data can be sent by sending STA. At the receiver of the receiving STA, the above-mentioned operation for 80+80 configuration can be reversed, and the combined data can be transmitted to the medium access control (MAC).

[0067] 802.11af and 802.11ah support operating modes below 1GHz. Channel operating bandwidths and carriers are reduced in 802.11af and 802.11ah relative to those used in 802.11n and 802.11ac. 802.11af supports 5MHz, 10MHz, and 20MHz bandwidths in the 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 may support instrument type control / machine type communications, such as MTC devices in macro coverage areas. MTC devices may have certain capabilities, such as limited capabilities, including support for (e.g., only support for) certain bandwidths and / or limited bandwidths. MTC devices may include batteries with battery life above a threshold (e.g., to maintain very long battery life).

[0068] WLAN systems that can support multiple channels and channel bandwidths (such as 802.11n, 802.11ac, 802.11af, and 802.11ah) include channels that can be designated as primary channels. 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 a STA (which supports the minimum bandwidth operating mode) from 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, because a STA (supporting only a 1MHz operating mode) is sending to the AP, the entire available band may be considered busy even if most of the band remains idle and may be available.

[0069] In the United States, the available frequency band for 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.

[0070] Figure 1D 1 is a system diagram illustrating the RAN 113 and the CN 115 in accordance with an embodiment. As noted 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.

[0071] The RAN 113 may include base stations 180a, 180b, 180c, but it should be understood that the RAN 113 may include any number of base stations while being consistent with an embodiment. The base stations 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 base stations 180a, 180b, 180c may implement MIMO technology. For example, the base stations 180a, 108b may utilize beamforming to send signals to and / or receive signals from the gNB base stations 180a, 180b, 180c. Thus, the base station 180a may, for example, use multiple antennas to send wireless signals to and / or receive wireless signals from the WTRU 102a. In an embodiment, the base stations 180a, 180b, 180c may implement carrier aggregation technology. For example, the base station 180a may send multiple component carriers to the WTRU 102a (not shown). A subset of these component carriers may be on an unlicensed spectrum, while the remaining component carriers may be on a licensed spectrum. In an embodiment, the base stations 180a, 180b, 180c may implement coordinated multi-point (CoMP) technology. For example, the WTRU 102a may receive coordinated transmissions from the base station 180a and the base station 180b (and / or the base station 180c).

[0072] The WTRUs 102a, 102b, 102c may communicate with the base stations 180a, 180b, 180c using transmissions associated with a set of parameters that may be scalable. For example, OFDM symbol spacing and / or OFDM subcarrier spacing may vary for different transmissions, different cells, and / or different portions of the wireless transmission spectrum. The WTRUs 102a, 102b, 102c may communicate with the base stations 180a, 180b, 180c using subframes or transmit time intervals (TTIs) of varying or scalable lengths (e.g., containing different numbers of OFDM symbols and / or continuously varying absolute time lengths).

[0073] The base stations 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 base stations 180a, 180b, 180c while not accessing other RANs (e.g., such as the eNodeBs 160a, 160b, 160c). In a standalone configuration, the WTRUs 102a, 102b, 102c may use one or more of the base stations 180a, 180b, 180c as mobility anchor points. In a standalone configuration, the WTRUs 102a, 102b, 102c may communicate with the base stations 180a, 180b, 180c using signals in an unlicensed band. In a non-standalone configuration, the WTRUs 102a, 102b, 102c may communicate / connect with the base stations 180a, 180b, 180c while also communicating / connecting with another RAN, such as the evolved Node-Bs 160a, 160b, 160c. For example, the WTRUs 102a, 102b, 102c may implement the DC principle to communicate with one or more base stations 180a, 180b, 180c and one or more evolved Node-Bs 160a, 160b, 160c substantially simultaneously. In a non-standalone configuration, the evolved Node-Bs 160a, 160b, 160c may act as mobility anchors for the WTRUs 102a, 102b, 102c, and the base stations 180a, 180b, 180c may provide additional coverage and / or throughput for serving the WTRUs 102a, 102b, 102c.

[0074] Each of the base stations 180a, 180b, 180c may be associated with a particular cell (not shown) and may be configured to handle radio resource management decisions, handover decisions, scheduling of users in UL and / or DL, support of 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. Figure 1D As shown, base stations 180a, 180b, 180c may communicate with each other via an Xn interface.

[0075] Figure 1D The illustrated CN 115 may include at least one AMF 182a, 182b, at least one UPF 184a, 184b, at least one session management function (SMF) 183a, 183b, and possible data networks (DNs) 185a, 185b. Although each of the foregoing elements is depicted as part of the CN 115, it should be understood that any of these elements may be owned and / or operated by an entity other than the CN operator.

[0076] The AMF 182a, 182b may be connected to one or more of the base stations 180a, 180b, 180c in the RAN 113 via an N2 interface and may act as a control node. For example, the AMF 182a, 182b may be responsible for authenticating users of the WTRU 102a, 102b, 102c, support of network slicing (e.g., handling of different PDU sessions with different requirements), selecting a specific SMF 183a, 183b, management of registration areas, termination of 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 services utilized by the WTRU 102a, 102b, 102c. For example, different network slices may be established for different use cases, such as services relying on ultra-reliable low latency (URLLC) access, services relying on enhanced mobile broadband (eMBB) access, and / or services for machine type communication (MTC) access, etc. The AMF 162 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.

[0077] 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 traffic routing through the UPF 184a, 184b. The SMF 183a, 183b may perform other functions such as managing and allocating WTRU IP addresses, managing PDU sessions, controlling policy enforcement and QoS, providing downlink data notifications, etc. The PDU session type may be IP-based, non-IP-based, Ethernet-based, etc.

[0078] The UPF 184a, 184b may be connected to one or more of the base stations 180a, 180b, 180c in the RAN 113 via an N3 interface, which may provide the WTRUs 102a, 102b, 102c with access to packet-switched networks, such as the Internet 110, 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, and providing mobility anchoring, etc.

[0079] The CN 115 may facilitate communications with other networks. For example, the CN 115 may include or may communicate with an IP gateway (e.g., an IP Multimedia Subsystem (IMS) server) that acts 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 networks 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 UPF 184a, 184b via the N3 interface to the UPF 184a, 184b and the N6 interface between the UPF 184a, 184b and the DN 185a, 185b.

[0080] Given that Figures 1A to 1D as well as Figures 1A to 1D Corresponding to the description of the present invention, one or more or all of the functions described herein with reference to one or more of the following may be performed by one or more simulation devices (not shown): WTRU102a-102d, base station 114a-114b, evolved Node B 160a-160c, MME 162, SGW 164, PGW 166, base station 180a-180c, AMF 182a-182b, UPF 184a-184b, SMF 183a-183b, DN 185a-185b and / or any other device described herein. The simulation device may be one or more devices configured to emulate 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.

[0081] The simulation device may be designed to implement one or more tests of other devices in a laboratory environment and / or in an operator network environment. For example, one or more simulation devices may perform one or more functions or all functions while being fully or partially implemented and / or deployed as part of a wired and / or wireless communication network in order to test other devices within the communication network. One or more simulation devices may perform one or more functions or all functions while being temporarily implemented / deployed as part of a wired and / or wireless communication network. The simulation device may be directly coupled to another device for testing purposes and / or may use over-the-air wireless communications to perform testing.

[0082] One or more simulation devices can perform one or more (including all) functions without being implemented / deployed as part of a wired and / or wireless communication network. For example, the simulation device can be used in a test scenario in a test laboratory and / or a non-deployed (e.g., testing) wired and / or wireless communication network to implement testing of one or more components. One or more simulation devices can be test equipment. Direct RF coupling and / or wireless communication via RF circuits (e.g., which can include one or more antennas) can be used by the simulation device to send and / or receive data.

[0083] The wireless communication system may be designed to accommodate different beamforming architectures and / or deployment scenarios. Hybrid beamforming may be supported. The number P of supported antenna ports (e.g., logical antenna ports) may vary (e.g., with 4, 8, 16, or 32 ports), such as Figure 2 As shown. The number of antenna ports (e.g., logical antenna ports) can be mapped to different antenna port configurations (e.g., (N1, N2) in the panel). For example, assuming that the number of dual-polarization and / or dual-polarization CSI-RS ports P is equal to 2N1N2, the 32 ports can be mapped to antenna configurations with (N1, N2) = (16, 1), (8, 2), or (4, 4), as shown Figure 3 shown.

[0084] Downlink (DL) transmissions in a wireless communication system may be performed based on one or more precoding schemes (e.g., non-codebook based precoding schemes). A precoder may be defined. A precoder matrix indicator (PMI) may be determined and / or used by a WTRU to estimate channel state information (CSI). Multiple (e.g., two) types of precoders may be supported, including, for example, a first type associated with type I CSI and a second type associated with type I CSI. Type I CSI (e.g., which may be associated with standard resolution) may be optimized for single-user MIMO (SU-MIMO) transmissions with a potentially large number of (e.g., up to 8) layers. Type I CSI (e.g., which may be associated with high resolution) may be optimized for multi-user MIMO (MU-MIMO) transmissions with multiple (e.g., up to 2) layers per scheduled WTRU and / or a total maximum number of layers (e.g., 12 layers). Type I and / or Type II codebooks may be composed of beam grids based on a two-dimensional (2D) DFT. Type I and / or Type II codebooks can implement beam-selected CSI feedback and / or phase-shift keying (PSK)-based in-phase combining between two polarizations. Type II codebook-based CSI feedback reports can include wideband and / or subband amplitude information for one or more selected beams.

[0085] The number of beams in a beam grid (GoB) may depend on (N1, N2) and (O1, O2), where (O1, O2) may represent an oversampling factor or a rotation factor in a type I or type II codebook. A rotated beam may be equivalent to an oversampled DFT beam with oversampling factors O1 and O2. For example, for (N1=4, N2=4) and (O1=4, O2=4), a total of 256 beams in a GoB may be formed, including 16 orthogonal DFT beams and 240 (e.g., 256-16) rotated beams, as shown in FIG. Figure 4 As shown. The rotated beams may be non-orthogonal. The beam width may depend on (N1, N2). The function of (O1, O2) may be applied (e.g., used) during a beam management or beam tracking process (e.g., during one or more beam scanning steps of a beam management or beam tracking process).

[0086] Downlink (DL) beam management (BM) may be aimed at adjusting one or more transmit (Tx) beams of a transmit and receive point (TRP) and / or one or more receive (e.g., Rx) beams of a WTRU. The DL beam management process may be performed in multiple steps (e.g., three steps), such as Figure 5 P-1, P-2, and P-3 are shown. For example, at P-1, the WTRU may measure one or more TRP Tx beams to facilitate (e.g., support) selection of a TRP Tx beam and / or a WTRU Rx beam. A wide beam scan may be applied in this step to determine the optimal Rx beam, and the WTRU may select an appropriate wide beam for UL transmission based on the measurement (e.g., based on a synchronization signal block (SSB)). At P-2, the WTRU may measure one or more additional TRP Tx beams to refine (e.g., change) an inter-TRP or intra-TRP Tx beam. For example, a base station (e.g., a gNB) may configure the WTRU with one or more CSI-RS resource sets, where each CSI-RS resource set may include multiple CSI-RS resources that the WTRU may use (e.g., during CSI measurement and / or reporting) for beam refinement (e.g., to select a refined or narrow beam). The gNB may determine a narrow beam for downlink transmission and / or uplink reception based on measurements (e.g., downlink measurements) performed by the WTRU on one or more candidate beams (e.g., refined or narrow Tx beams). At P-3, the WTRU may measure the same TRP Tx beam to determine (e.g., change) the Rx beam of the WTRU (e.g., if the WTRU is configured for beamforming). The WTRU may also determine the Tx beam for uplink transmission based on downlink measurements of one or more Rx beams of the WTRU. In this step, the gNB may repeat one or more beams (e.g., narrow beams) for the WTRU to perform measurements.

[0087] Beam management may be performed based on a hierarchical beam search principle. For example, the WTRU may (e.g., first) select a wide beam from a set of candidate wide beams (e.g., based on one or more SSBs), and may, for example, feedback (e.g., report) the selected beam (e.g., corresponding SSB) to the network via a physical random access channel (PRACH) during an initial access phase. In response to receiving the feedback, the network (e.g., a network device such as a base station) may send a plurality of refined narrow beams based on the wide beam (e.g., SSB) selected by the WTRU (e.g., the refined narrow beams may provide initial spatial information to the WTRU). The refined narrow beams may be associated with corresponding CSI measurement and / or reporting configurations, which may be used by the WTRU to determine the refined narrow beams and report the determination to the network.

[0088] One or more beam tracking techniques may be employed to ensure that a suitable (e.g., optimal) beam pair is maintained for data transmission / reception if the WTRU moves or if the operating environment of the WTRU changes. The base station may (e.g., periodically) broadcast an SBS, from which the WTRU may determine the strength of one or more beams (e.g., as indicated by corresponding RSRP values) by measuring the SBS. The WTRU may report the determined (e.g., measured) beam strength values ​​to the base station, and the base station may decide a suitable (e.g., optimal) transmit beam for the WTRU. The beam tracking techniques described herein may be used for wide and / or narrow beam selection and changing. The beam tracking techniques may be used to detect the strongest narrow beam based on WTRU measurements of a CSI reference signal (CSI-RS) and / or an SBS.

[0089] The WTRU may use one or more CSI reference signals to estimate the channel and / or transmit a report about the estimate to a base station (e.g., a gNB). For example, the WTRU may measure the DL CSI-RS and may report the measurement via one or more uplink (UL) messages. The measurement may be used by the base station for mobility checks and / or beam management. Multiple (e.g., three) types of CSI reports may be supported, including, for example, periodic reports, semi-persistent reports, and aperiodic CSI reports. Periodic CSI reports may be configured by the network to be generated and sent with a certain period. For example, periodic CSI-RS transmissions may be configured so that they may occur once every Mth time slot (e.g., based on parameters such as CSI-ResourcePeriodicityAndOffset), where M may range from 4 to 640 time slots. Measurement reporting of these CSI-RS transmissions may be performed via the PUCCH. Semi-persistent CSI reporting may be similar to periodic CSI reporting (eg, in terms of configuration), except that activation and deactivation of CSI-RS transmissions for semi-persistent CSI reporting may be controlled by the network (eg, via MAC layer transmissions such as MAC CEs).

[0090] Layer 1 RSRP (L1-RSRP) such as RI-RSRP and / or SSB-index-RSRP may be used during beam management or beam tracking to identify a suitable beam (e.g., best downlink beam). SSB-Index-RSRP may be measured and / or reported based on the SSB associated with the beam. CRI-RSRP may be measured and / or reported based on the CSI-RS resource associated with the beam.

[0091] Beam management may include beam inference in the time domain and / or the spatial domain, for example, for overhead and / or latency reduction, beam selection accuracy, etc. The inference (and / or management) may be performed on the network side, on the WTRU side, or on both sides. Performing beam inference and / or management on the network side may reduce the computational complexity of the WTRU, in which case the WTRU may still provide feedback to the network, such as L1-RSRP feedback. There may be overhead associated with such feedback, and techniques such as RSRP compression techniques may be used to reduce the overhead. Performing beam inference and / or management on the WTRU side may reduce or eliminate the aforementioned feedback overhead (e.g., because the WTRU may predict and / or indicate the appropriate beam via the CSI-RS Resource Indicator (CRI) and therefore not report the measured L1-RSRP), but this approach may increase the power consumption of the WTRU, for example, due to the computational complexity of the operation.

[0092] Beam inference and / or management may be similar to (e.g., at least to some extent) selecting a grid or pixel from a 2D image of beams, where the grid (or pixel) of the 2D image may represent the spatial coverage area of ​​the selected beam (e.g., each grid in the 2D image may correspond to a beam, and the area of ​​the grid may correspond to the width of the beam, such as 3 dB). For spatial domain (SD) beam inference, a variety of methods may be used. Using a first example approach, a suitable (e.g., optimal) beam may be inferred based on measurements of a set or subset of wide beams, such as Figure 6 As shown. In this example, a subset of wide beams (e.g., corresponding to SSBs) may be measured, and one or more narrow (e.g., fine) grids of beams may be predicted based on the measurements, from which a suitable (e.g., optimal) beam may be further predicted. This approach may be referred to or categorized as a super-resolution approach. Using a second example approach, a suitable or optimal beam (e.g., a narrow beam) may be inferred based on measurements of a set or subset of narrow beams, such as Figure 7 As shown. In this example, a subset of narrow beams (e.g., corresponding to CSI-RS) can be sent for measurement, and the top k beams sorted by the measurement results can be predicted as suitable beams. This method can be called or classified as an interpolation or recovery method (e.g., because the beams are recovered based on partial data or information of the same beam resolution).

[0093] A wireless communication system with an unlimited number of antennas in a limited space may be referred to as a holographic MIMO (H-MIMO) or large intelligent surface (LIS) system. Beamforming may be performed in such an H-MIMO and / or LIS system and may be referred to herein as holographic beamforming. Holographic beamforming may be performed in a dynamic manner, for example using a configurable (e.g., fully configurable) metasurface that may provide an architecture with lower cost, size, and / or power consumption compared to traditional digital, analog, and / or hybrid architectures. The metasurface may include a thin electromagnetic (EM) material that may generate EM rays in an intelligent manner (e.g., by configuring an array of phase-shifting elements and delivering desired EM behavior in a reconfigurable pattern). This may differ (e.g., at least in some aspects) from traditional phased array and / or active antenna systems.

[0094] Figure 8 An example of an H-MIMO architecture is shown. As shown, the H-MIMO architecture may include multiple (e.g., three) components, such as, for example, a metasurface having N radiating elements, which may be configured to transmit a signal having a carrier frequency f cThe reference signal feed antenna of the H-MIMO beamforming can be configured to synthesize the baseband of the EM rays. If the antenna size or antenna elements become comparable to the link distance, the operating condition can meet the Fresnel region, in which near-field propagation can occur. The degree of freedom (DoF) associated with H-MIMO beamforming can be greater than 1 (e.g., for line-of-sight (LoS) channels and / or in near-field conditions). The H-MIMO beamforming framework can be used to enhance the MIMO capacity of LoS channels.

[0095] The beamforming gain in a hybrid beamforming architecture may be constrained by the number of transceiver units (TxRUs), which in turn may constrain the number of logical antenna ports. This may be because the beamforming gain may be synthesized from both analog and digital beamformers, and the beamforming gain in such a hybrid arrangement may be difficult to achieve at an optimal level. H-MIMO may provide greater beamforming gain than a hybrid beamforming scheme because multiple (e.g., all) antenna elements are configurable. H-MIMO may also allow the network to transition from a logical domain (e.g., which may include antenna ports) to a physical domain (e.g., which may include RF ports), for example, by viewing the radio environment as a software entity that may be programmed, reconfigured, and / or optimized.

[0096] The deployment of ultra-large-scale MIMO can enhance beam quality, mitigate beam interference, and / or increase the opportunity for spatial multiple gain. As the number of antenna elements increases, narrower beams with better beam quality can be formed (e.g., as a result of increased beamforming gain). For example, an H-MIMO system may include 160,000 antenna elements with a 1×1 square meter element surface, 1 / 4 wavelength antenna spacing, and / or a center frequency of 30 GHz. Because traditional beamforming techniques such as hybrid analog and digital beamforming may no longer be applicable due to network routing and / or hardware limitations, the ultra-large number of antenna elements and / or the ability to generate narrow beams in such an H-MIMO system may affect the way beam management is performed. The amount of time spent in a beam search may be proportional to the number of beams (e.g., Tx beams) to be searched, and therefore, beam searches may take longer in H-MIMO systems. If H-MIMO is deployed, greater CSI-RS signaling overhead and / or latency associated with signal monitoring, signal measurement, and / or network response may also be expected.

[0097] Techniques such as beam inference may be used to reduce beam search overhead and / or time spent on beam management. The performance of a beam inference model, such as one based on artificial intelligence / machine learning (AI / ML), may depend on several factors, including, for example, spatial, temporal, and / or frequency variations of the channel due to changes in WTRU mobility or the associated environment, beam resolution, and / or the number of beams to scan. There may be deficiencies in existing beam inference models that may render them inadequate for H-MIMO. For example, Figure 6 As shown, the accuracy and / or inference error of beam inference based on a partially wide beam (e.g., SSB) may be hampered by the limitations of a super-resolution model such as an AI / ML-based model, where the partially wide beam may be viewed as a low-resolution image (e.g., a 2D image of the beam). A refined (e.g., narrow) beam may be predicted or inferred (e.g., by a network device) from a subset of measured beams. The predicted beam (e.g., the refined or narrow beam) may not be among the first set of beams or reference signals (RS) measured by the WTRU, or may not be among the subset of the first measured beams or reference signals. Therefore, the network device (e.g., a base station) may send additional information about the inferred or predicted beam (e.g., the refined or narrow beam) to the WTRU. For example, the network device may configure and send a second set of reference signals or beams for the WTRU to measure and select (e.g., predict) one or more beams or reference signals to feed back to the network (e.g., so that the network can determine which transmission configuration indicator (TCI) state may be activated for PDCCH or PDSCH transmission). In these cases, if the spatial information of the reference signal or beam is unknown to the WTRU, the WTRU may perform a beam search, which may result in increased computational effort and / or latency. Because narrower (e.g., thinner) beams may be generated or expected in an H-MIMO system due to a larger number of antenna elements in a finite surface, there may be a high probability that the predicted or inferred beam (e.g., a refined or narrow beam) may not be among the set or subset of measured beams. This may mean that additional beam search efforts by the WTRU may be frequent and may increase the overhead and / or latency associated with beam management. Furthermore, as Figure 2 As shown, the number of TxRUs in a hybrid beamforming architecture may be limited. The quality of the beam (e.g., as a result of composite beamforming and / or precoding based on analog and digital beamforming weights) may also be constrained by the hybrid beamforming architecture. In contrast, the antenna elements (e.g., each antenna element) of an H-MIMO system may be programmable, so the beamforming weights may not be limited by the hybrid or analog beamforming architecture, and the beam management performance may be improved by exploiting the programmable properties of the elements.

[0098] Beam management including beam inference techniques may be used to support H-MIMO, large intelligent surfaces (LIS), and / or various beamforming architectures, such as all-digital, hybrid, and / or analog beamforming architectures. The network device may employ different beam management (including beam inference) techniques than the WTRU. For example, beam interference at the network device may be reported for feedback and / or other processes using a measurement metric (e.g., L1-RSRP) that is different from the metric used by the WTRU. A hierarchical beam indication mechanism (e.g., configuration and / or signaling associated with a hierarchical spatial arrangement of beams) may be implemented so that the network device and the WTRU may exchange beam information (e.g., for beams of different levels or beams with different spatial resolutions). In a first example use case, both the network device and the WTRU may learn beam resolution and / or quasi-co-location (QCL) information of the beams based on the hierarchical beam structure (e.g., the hierarchical spatial arrangement of beams). For example, this use case may apply if the network device uses wide beams or narrow beams for beam inference and the WTRU reports the inferred narrow beams to the network (e.g., when beam inference is enabled on the WTRU side). In a second example use case, the network may use wide beams or narrow beams for beam inference and may indicate the inferred beams to the WTRU (e.g., when beam inference is performed on the network side) so that the WTRU can perform fast beam pairing.

[0099] A hierarchical reference signal or beam structure (e.g., a hierarchical arrangement of reference signals or beams) may be implemented, where the term "reference signal" and the term "beam" may be used interchangeably in the relevant examples provided herein. For example, one or more sets of hierarchical reference signals (RS) may be configured or predefined in the spatial domain for the WTRU and / or the network based on a corresponding beam grid, and the network and / or the WTRU may use the predefined or configured hierarchical beams for beam mapping, beam indication, beam inference, etc. The hierarchical reference signal or beam may have one or more of the following attributes.

[0100] Multiple (e.g., K) different hierarchical levels of reference signals or beams may be configured or defined (e.g., based on a hierarchical spatial arrangement of beams). For level k (e.g., 1≤k≤K), m reference signals or beams may be configured or defined (e.g., arranged into a grid of beams). (Each) reference signal or beam may have its own coverage area (e.g., represented by a square in a 2D image of the beam, as shown in FIG. 1 ). Figure 9(a) to Figure 9(e)As shown). If a reference signal or beam at level k+1 is within (e.g., contained by) the beam coverage of a reference signal or beam at level k (e.g., the square at level k+1 is within the square at level k, as shown in FIG. 9), then the reference signal or beam covering the square at level k+1 (e.g., indicating beam coverage) has a QCL type D relationship with the reference signal or beam at level k. In other words, the (3dB) beamwidth (or spatial coverage) of the reference signal or beam at level k may cover the reference signal or beam at level k+1 (e.g., the square at level k+1 may be within the square at level k). In terms of the QCL assumption, a reference signal or beam at level k may have m (e.g., m=m=2) at the next level (e.g., at level k+1). 2^(k) ) QCL reference signals or beams.

[0101] Figure 9(a) to Figure 9(e) Examples of hierarchical RS / beam arrangements or designs are shown. In these examples, four levels of hierarchical reference signals or beams may be defined for the spatial domain (SD) (e.g., the definition may indicate a hierarchical spatial arrangement of reference signals or beams). Reference signals or beams at lower levels may have wider beamwidths, while reference signals or beams at higher levels may have narrower beamwidths. The squares in the 2D image shown in FIG9 may represent beam coverage areas (e.g., 3 dB beamwidths). At lower levels, the squares may have larger areas, which may mean wider beamwidths, and the areas may become smaller as the levels become higher (e.g., the beamwidths may become narrower). The union or combination of beam coverage areas within the same level may correspond to a specific spatial domain. A reference signal or beam at level k may be configured to contain m QCL reference signals or beams at the next level (e.g., level k+1) through a hierarchical spatial arrangement. Fig.18 Example designs of QCL assumptions with different levels of reference signals (e.g., CSI-RS) or beams are shown. Fig.18 In the example of , three levels of beams can be used to cover the same spatial region. The first level (e.g., k=1) can include 64 beams (8x8) to cover the spatial region, the second level (e.g., k=2) can include 256 beams (16x16) to cover the same spatial region, and the third level (e.g., k=3) can include 1024 beams (32x32) to cover the same spatial region. The (3dB) beamwidth of (e.g., each) beam at the second level and / or the third level can be QCLed with the beam at the first level. Thus, (e.g., each) beam at the first level (e.g., level k=1) can be QCLed with the m=2 beam at the second level (e.g., level k=2). 2^1 =22 = 4 beams for QCL, and m = 2 at the third level (eg, level k = 3) 2^2 =2 4 = 16 beams are QCLed. Therefore, when a beam at a particular level is specified, one or more beams at the next level can be determined based on the hierarchical QCL relationship.

[0102] The reference signals or beams at (e.g., each) a particular level (e.g., level k) may be designed or represented by codewords in a codebook (e.g., a DFT codebook). For example, configuration information transmitted by a network device to a WTRU may include multiple codebooks indicating hierarchical spatial arrangements of reference signals or beams at different levels (e.g., different levels may correspond to different spatial resolutions of beams). The configuration information may, for example, indicate that for level k, there may be N in the vertical and horizontal spatial directions, respectively. (k) and M (k) As shown in Figure 9, N (k) and M (k) At level 1 it can be equal to 4, at level 2 it can be equal to 8, at level 3 it can be equal to 16, at level 4 it can be equal to 32, and so on. Therefore, levels 1, 2, 3, and 4 can represent 4, 8, 16, and 32 beams in the vertical and horizontal spatial directions of each level. Thus, let 1≤i1 (k) ≤N (k) represents the i-th vertical beam at level k, and 1≤i2 (k) ≤M (k) represents the i-th horizontal beam at level k, which can be based on the index i1 in the corresponding 2D beam image or codebook (k) and i2 (k) To indicate or identify the (eg, each) reference signal or beam at that level.

[0103] 9, a beam at level k (e.g., level 1) may cover the same area as the union of m sub-beams at level k+1 (e.g., level 2). The m sub-beams at the next level may be generated, for example, based on a 2D DFT with rotated beams (e.g., based on a type I codebook). Fig.10 An example is shown, where 4 sub-beams can be covered by sub-beams at level k+1 (eg, each sub-beam is covered by ((i1 (k+1) ,i2 (k+1)) representation), and the combined sub-beams can cover the same area of ​​the beam at level k. The reference signal or beam (e.g., a sub-beam or narrower beam) at level k+1 can be a QCL type D with the beam at level k. This QCL relationship (e.g., spatial relationship) between different hierarchical beam levels can be used for H-MIMO beam management to reduce beam search work (e.g., because once a beam at one level is identified, a sub-beam at the next level can also be identified). For example, Fig.18 As shown, in the case of three levels of beams, the first level beams (e.g., 64 beams) may be assigned a codebook (e.g., having 64 codewords, one of which may be linked to a corresponding codeword in the codebook). Since beams at different levels may have a QCL relationship, the codebooks associated with each level may also have a hierarchical relationship.

[0104] For example, during a beam inference training phase for H-MIMO (e.g., learning an AI / ML model for beam inference), the WTRU may be configured (e.g., pre-configured) with a hierarchical beam structure or spatial arrangement. The WTRU may report measurement results for one or more CSI-RS sets that may be associated with multiple levels of beams (e.g., there may be one CSI-RS resource set for each level of beam). The configured CSI-RS resource sets may include a large number of CSI-RS resources (e.g., due to the size of H-MIMO). The larger the size of the metasurface in H-MIMO, the higher the number of CSI-RS resources that may be measured and / or reported. Beam management associated with H-MIMO may be performed using the hierarchical beam structure described herein to reduce CSI-RS resource signaling overhead.

[0105] In an example, if / when the network device is configured to perform beam inference, beam management associated with H-MIMO may be performed. For example, during an initial access phase, one or more of the following may be performed. A base station (e.g., a gNB) may broadcast an SSB. The base station may send an SSB at a specific time within an SSB burst set. The base station may send an SSB index per beam in a spatial direction, or the base station may send multiple SSBs (e.g., with different SSB indices) on the same beam or in the same spatial direction. During the initial access phase, there may be no radio link establishment before the WTRU completes the random access procedure. The WTRU may measure and select a suitable beam with a specific SSB index. The WTRU may perform random access on a random access resource associated with the selected SSB index. If beam inference is enabled on the network (e.g., base station or gNB) side, during the random access procedure, the base station may configure the WTRU to report the highest / best q (e.g., q=4) SBSs (e.g., with the highest RSRP) and the corresponding L1-RSRP values ​​and / or SSB indices. SSB can be used for beam inference because (e.g., at least in part) an SSB or a set of SSB bursts can be used for initial access, and the network can send SSBs even if not every SSB burst is sent (e.g., at least some SSB bursts in an SSB burst set can always be sent).

[0106] If the base station (e.g., gNB) configures (e.g., enables) the use of beam inference during the initial access phase (e.g., via system information (SI)), the WTRU may report the best / highest q SBSs and the corresponding L1-RSRP values ​​and / or SSB indices in the PUSCH payload. In a two-step RACH procedure, the best / highest q L1-RSRPs and SSB indices may be included in the PUSCH payload in step 1 (e.g., via transmission of MsgA). In a four-step RACH procedure, the best / highest q L1-RSRPs and / or SSB indices may be included in the PUSCH payload in step 3 (e.g., via transmission of Msg3).

[0107] The base station may determine (e.g., depending on the RACH resources used by the WTRU) which SSB (e.g., a wide beam) is selected by the WTRU, and the random access procedure may be completed based on the determined SSB (e.g., the beam corresponding to the SSB). The base station may configure the WTRU with multiple groups of beams (e.g., arranged in a hierarchical structure) that may be associated with one or more CSI-RS resource sets (e.g., each CSI-RS source set may include multiple CSI-RS resources). For example, after the WTRU completes initial access and / or enters an RRC connected state, the configuration information may be sent from the base station to the WTRU. The base station may associate a low (e.g., lowest) level beam (e.g., level 1) with an SSB or SSB index, such as Fig.11 As shown. The association can be done (e.g., configured), for example, via RRC signaling. A one-to-one mapping between beams at one level and CSI-RS resources may or may not be required. The association between the hierarchical beam structure and the CSI-RS resources may be as described herein.

[0108] A network device such as a base station and / or a WTRU may be configured to perform one or more of the following, for example in an RRC connected state. A network device (e.g., a base station, a gNB, or a TRP) may configure the WTRU with one or more CSI-RS resource sets (e.g., including non-zero power CSI-RS resources), for example, via an information element such as CSIresourceConfig. The network device may indicate a hierarchical reference signal or beam via one or more QCL type D chains, where a CSI-RS resource at level k+1 (e.g., corresponding to a beam) may be configured with a QCL type D source RS at level k. This may indicate that the beam coverage of the CSI-RS at level k+1 is within the beam coverage of the CSI-RS at level k. In this way, the WTRU may use QCL chains to track the RS / beam hierarchy.

[0109] The network device may configure multiple non-zero power (NZP) CSI-RS resources to share the same physical time-frequency resources (e.g., the same time slot and / or port number), for example, to reduce resource overhead. The network device may perform CSI-RS beam scanning (e.g., partial CSI-RS beam scanning), and the WTRU may measure one or more configured NZP CSI-RS resources (e.g., based on a semi-persistent CSI reporting configuration) and report the measurement results (e.g., L1-RSRP with CRI) to the network device. For example, the WTRU may perform L1-RSRP (e.g., CSI-RSRP) measurement and reporting, and the network device may use the report provided by the WTRU as an input for beam inference.

[0110] The network device may, for example, issue a CSI request in a DCI to trigger a CSI-RS report (e.g., an aperiodic (AP) CSI-RS report). For example, the network device may trigger an AP CSI-RS report on CSI-RS #1 and CSI-RS #2. AP CSI-RS #2 may be a narrow RS or beam predicted by the network device (e.g., for use by a WTRU), and AP CSI-RS #1 may be an intermediate RS or beam for the WTRU to perform hierarchical beam search or tracking. The network device may send AP CSI-RS #1 (e.g., repeatedly) with a medium-width beam (e.g., the beam used for AP CSI-RS #1 may be a medium or lower-level beam). The medium-width beam may be QCL (e.g., configured via the network) with a wide beam (e.g., corresponding to an SSB or CSI-RS) and may be sent before AP CSI-RS #2 (e.g., in a time slot before the transmission of CSI-RS #2). The network device may transmit AP CSI-RS #2 in a narrow beam (e.g., as a high-level beam) that may be QCLed with AP CSI-RS #1 (e.g., configured via the network). Based on such an arrangement or configuration, the WTRU may report CSI for CSI-RS #2 and may not report CSI for CSI-RS #1 (e.g., because CSI-RS #2 is associated with a narrower beam that is QCLed with CSI RS #1), for example, to reduce reporting overhead.

[0111] The QCL assumptions or links of the reference signals or beams (e.g., the hierarchical levels of the reference signals or beams) may be configured, for example, to maintain RS or beam QCL chains. Such a hierarchical structure or arrangement may be implemented for H-MIMO that may use narrow beams. For example, one or more of the following may be implemented to reduce configuration and / or other signaling overhead.

[0112] An information element (e.g., hierarchicalBeamMapping) may be included in CSI-RS related configuration information (e.g., such as CSI-ResourceConfig) sent by a network device to a WTRU. If the information element is set to ON, the WTRU may assume that the CSI-RS resources in the CSI-RS / CSI SSB resource sets may have a hierarchical structure, e.g., as shown in FIG. 9 . For example, the WTRU may receive configuration information indicating that CSI-RS resource set #1 is associated with (beam) level 1 (e.g., assuming that CSI-RS resource set 1 is the lowest level CSI-RS resource set in CSI-ResourceConfig), CSI-RS resource set 2 is associated with beam level 2, and so on. Such configuration information may indicate a hierarchical structure of CSI-RS resource sets, e.g., for each level. If the information element (e.g., hierarchicalBeamMapping) is set to OFF, the WTRU may assume that there is no hierarchical beam structure for the CSI resource / CSI resource set configuration (e.g., the WTRU may assume that the configured CSI resource sets (IDs) have no hierarchical mapping between them).

[0113] The WTRU may assume that the lowest CSI resource set is associated with the lowest level of hierarchical beams, and so on, until the last configured CSI resource set (e.g., when hierarchical beam mapping is ON). The WTRU may assume that the number of hierarchical RS / beam levels may be equal to the number of CSI resource sets configured in CSI-ResourceConfig. For example, the SSB beams in an SSB burst set may default to the lowest level of hierarchical beams (e.g., at level 1), where SSB is the transmit beam in the lowest level. The number of SSB beams may be determined based on an information element (e.g., such as ssb-PositionsInBurst), for example, Fig.11 shown.

[0114] A network device (e.g., a base station or gNB) may configure a WTRU with multiple CSI resources in (e.g., each) CSI resource set. The network device may or may not configure a QCL linkage or correspondence (e.g., a QCL assumption) for the configured CSI-RS resources. The number of CSI resources in a CSI resource set may be less than or equal to the number of reference signals or beams at level k of a hierarchical beam structure or arrangement. (e.g., each) CSI-RS resource in a CSI-RS resource set (e.g., a CSI-RS resource set k corresponding to (beam) level k) is QCL type D to the next higher number CSI-RS resource set (e.g., a CSI-RS resource set k+1 corresponding to beam level k+1). For example, a network device (e.g., a base station or gNB) may provide CSI configuration information (e.g., CSI-ResourceConfig) and set the number of sub-beams m (e.g., m=2 p , p=1,2,...) is set to 4 (e.g., as part of the CSI configuration information) for the next hierarchical level increase (e.g., each beam at level k can contain 4 sub-beams at level k+1). With this CSI resource configuration, the network device can allocate m (e.g., m=4) CSI-RS resource sets, each of which can be mapped to Fig.10 The corresponding spatial arrangement of the beams shown. For example, CSI-RS resource set #1 can be mapped to hierarchical beam level 1, CSI-RS resource set #2 can be mapped to hierarchical beam level 2, CSI-RS resource set #3 can be mapped to hierarchical beam level 3, and CSI-RS resource set #4 can be mapped to hierarchical beam level 4. In this way, the beam hierarchy can be represented via different CSI-RS resource sets configured by the network (e.g., via CSI-ResourceConfig). Additional spatial information (e.g., indicated by one or more codeword indices) can be associated with the CSI-RS resource configuration. For example, a CSI-RS resource can be associated with a codeword index, and the CSI-RS resource set (level) can be linked to a corresponding codebook, for example, as shown in FIG. Fig.18 and Fig.12As shown. When hierarchicalBeamMapping is set to ON, the WTRU may assume that the configuration is valid (e.g., when hierarchicalBeamMapping is set to ON, the WTRU may assume that the additional spatial information indicated by the codeword index associated to the CSI-RS resource is valid). The network device may configure multiple CSI-RS resources and associated spatial information (e.g., codeword IDs) in (e.g., each) CSI-RS resource set (e.g., independently). For example, the network device may configure 16 CSI-RS resources and their corresponding codeword IDs in CSI-RS resource set #1, 32 CSI-RS resources and their corresponding codeword IDs in CSI-RS resource set #2, and so on. In the example, more (e.g., more than 32) CSI-RS resources may be configured for higher-level CSI-RS resource sets because a higher number of CSI-RS resource sets (e.g., hierarchical levels) may correspond to a larger number of beams in the spatial domain (e.g., beams with finer or narrower beamwidths). In this way, the number of CSI-RS resources in a CSI-RS resource set used for beam inference may be lower because beam inference may not use full beam scanning. Finer / narrower beams may also lead to higher beam inference accuracy (e.g., assuming that the number of CSI-RS measurements may be sufficient for each level of beam).

[0115] A network device (e.g., a base station or gNB) may use a CSI-RS reporting period as a beam inference monitoring or verification period. The monitoring period (e.g., for beam inference) may be set by a time, the value of which may be configured by the network device. The network device may implement beam inference objectives based on periodic, aperiodic, or semi-persistent CSI measurements and reports. For example, in (e.g., each) CSI-RS reporting period, the network device may configure the WTRU with CSI configuration resources for CSI L1-RSRP reporting. In this regard, the network device may configure the WTRU with multiple CSI-RS resource sets and may associate (e.g., each) configured CSI-RS resource set with a beam level in a beam mapping. The network device may also configure the WTRU with multiple (NZP) CSI-RS resources in (e.g., each) CSI-RS resource set for L1-RSRP measurement and reporting. As described herein, partial beam measurements may be performed based on a low- to medium-resolution 2D image of the beam, from which the WTRU may obtain beam information for beam inference and / or other purposes, such as spatial coverage information from one or more CSI-RS resource sets configured for measurement (e.g., if parameters such as hierarchicalBeamMapping are set to ON in CSI-ResourceConfig).

[0116] Fig.12 An example of CSI configuration information (e.g., CSI-ResourceConfig) and a beam management process associated with H-MIMO (e.g., in the RRC connected state) is shown. Fig.12 As shown, the network device may configure the WTRU with multiple CSI resource sets (e.g., CSI resource set #1 and CSI resource set #2, where #1 is the lowest CSI-RS resource set ID) in the CSI resource configuration for CSI reporting (e.g., L1-RSRP reporting). The first CSI-RS resource set (e.g., CSI resource set #1) may be configured with 8 NZP CSI-RS resources for beam inference, and the second CSI-RS resource set (e.g., set #2) may be configured with 2 NZP CSI-RS resources. For beam inference, the network device may scan a partial set of CSI-RS beams. For example, the network device may Fig.12As shown, level 1 (e.g., wide, DFT-based) beams {(1,1), (1,3), (2,2), (2,4), (3,1), (3,3), (4,2), (4,4)} are sent in the beam inference monitoring period, and those level 1 beams may be mapped to the eight CSI-RS resources configured in CSI-RS resource set #1. During the beam inference phase, the WTRU may not be informed of the actual beam information (e.g., DFT-based Tx beam information). (e.g., each) CSI-RS resource in CSI-RS resource set #1 (e.g., corresponding to level 1 beams) may be QCLed with an SSB index, and the WTRU may measure the 8 CSI-RS resources in CSI-RS resource set #1 and report the measurement results to the network device (e.g., via PUCCH or PUSCH). The network device may predict one or more narrow beams or refined beams based on the measurement results (e.g., L1-RSRP) reported by the WTRU, and may notify the WTRU of the inferred or predicted beams (e.g., because the beam predicted by the network device may not be among the beams measured and reported by the WTRU using CSI-RS resource set #1). The network device may apply the inferred beams to the non-periodic CSI-RS reporting, and may set the repeat flag to "ON" for the NZP CSI-RS resources of the higher or same CSI-RS resource set for the WTRU to perform CSI reporting to determine the best inferred beam and tune its receive spatial parameters (e.g., the WTRU may perform Rx beamforming). The network device may also signal one or more indices of a codebook (e.g., a 2D DFT codebook) associated with the inferred beam (e.g., CSI-RS resource) to the WTRU so that the WTRU can determine or identify the inferred beam based on the codebook. As described herein, such a codebook may be configured for a set of beams that may include an inferred beam, and thus, the codebook may provide spatial information about the beam to the WTRU. In an example, the network device may signal the CSI-RS resources in the higher CSI-RS resource set to the WTRU (e.g., together with the aforementioned codebook index) to indicate the spatial information (e.g., resolution and / or level) of the inferred beam. The WTRU may use the provided spatial information for beam pairing and may avoid performing additional beam scans to verify the inferred beam, thereby reducing the time associated with beam search and feedback.

[0117] The network device may configure the WTRU with aperiodic CSI-RS reporting. For one or more inferred or predicted beams, the network device may set the repeat flag associated with CSI-RS resource set #2 to “ON”, such as Fig.12 The network device can be associated with the inferred beam (e.g., Fig.12The corresponding codebook index associated with the beams 35 and 36 shown (5,3) and (5,4)) is signaled to the WTRU (e.g., via MAC-CE or PDCCH payload), and aperiodic CSI-RS reporting for the inferred beam may be requested (e.g., configured). In response, the WTRU may determine the spatial information associated with the predicted beam (e.g., for Rx beam reception) based on the selected CSI-RS resource set (e.g., #2 in this example) and / or the codebook index indicated by the network device. The WTRU may measure the beam inferred and indicated by the network device, and report the measurement results (e.g., including the CRI associated with the measurement) back to the network device so that the network device can determine the best beam for the WTRU. In a subsequent (e.g., next) beam prediction or inference cycle or period, the network device may remap a different set of beams (e.g., 2D DFT beams) such as {(1,2), (1,4), (2,1), (2,3), (3,2), (3,4), (4,1), (4,3)} to CSI-RS resources 1 to 8 in CSI-RS resource set #1. Using these techniques, beam inference may be performed based on a random or arbitrary beam pattern or based on a fixed beam pattern. In addition, beam inference may be implemented with the proposed hierarchical beam structure, and the WTRU may use additional spatial information (e.g., codeword ID) to identify the beam direction.

[0118] Beam inference and / or hierarchical beam searching may be supported (e.g., performed) for beam management. A network device (e.g., a base station or gNB) may configure multiple CSI-RS resource sets for the WTRU to perform measurements (e.g., L1-RSRP measurements). The network device may configure CSI reporting for a specific CSI-RS resource set such that the WTRU may report (e.g., only one) L1-RSRP for that CSI-RS set for hierarchical beam searching. For other CSI-RS resource sets, the WTRU may report multiple L1-RSRPs for beam inference.

[0119] Multi-resolution beam inference may be supported for H-MIMO. Multi-resolution beam inference may allow different beam resolutions (e.g., squares of different sizes as shown in FIG. 9 ) to be used as input for beam inference. Using this approach, beam inference accuracy and super-resolution performance may be improved. A network device (e.g., a base station, gNB, or TRP) may activate different CSI-RS resource sets and CSI-RS resources in each CSI-RS resource set for the WTRU to measure, and may configure the WTRU with different beam inference periods.

[0120] The WTRU may report channel estimates (e.g., including I and Q components) for each configured CSI-RS resource in a CSI-RS resource set (e.g., instead of reporting L1-RSRP for each NZP CSI-RS resource). For example, the WTRU may report channel estimates to enhance the performance of CSI reporting. The CSI reporting type may be configured for the WTRU to report measurements of received reference signals, which may be used as input to beam inference.

[0121] Fig.13 An example of a beam inference process associated with H-MIMO is illustrated (e.g., in an RRC connected state). As shown, a network device (e.g., a base station or gNB) may configure a WTRU with multiple CSI-RS resource sets and multiple NZP CSI-RS resources for each CSI resource set to perform CSI reporting (e.g., L1-RSRP CSI reporting), and the network device may use the report as an input for beam inference. The network device may perform partial CSI-RS beam scanning. The WTRU may measure one or more configured NZP CSI-RS resources (e.g., based on a semi-persistent CSI reporting configuration) and may report the measurement results (e.g., L1-RSRP with CRI) to the network device. The network device may perform beam inference based on the WTRU's reports. The network device may configure and / or request non-periodic CSI reports from the WTRU to verify the beam inferred or predicted by the network device. In some cases (e.g., if a configuration parameter such as hierarchicalBeamMapping is set to ON), the network device may signal one or more beam indices (e.g., additional DFT beam indices) and may transmit a CSI-RS with a repeat flag set to ON so that the WTRU performs Rx beamforming. In some cases (e.g., if hierarchicalBeamMapping is set to OFF), the network device may perform (e.g., fall back to) beam scanning for one or more predicted beams, and the WTRU may report measurements associated with the scanned beams (e.g., L1-RSRP) back to the network device. In response, the network device may perform beamforming (e.g., Rx beamforming) based on the measurements reported by the WTRU (e.g., L1-RSRP measurements) and with the repeat flag set to ON.

[0122] In an example, the WTRU may be configured to perform beam management and / or beam inference. Performing beam inference at the WTRU may reduce feedback (e.g., L1-RSRP feedback) overhead associated with one or more configured NZP CSI-RS resources and / or improve beam inference accuracy. Since the beam inferred or predicted by the WTRU may not be in the configured list (e.g., for CSI-RS resources, TCI state, etc.), the WTRU may report the inferred beam to the network device so that the network device may determine the beam to use for DL ​​transmission based on the information reported by the WTRU. For example, during an initial access phase, the WTRU or the network device may perform one or more of the following. The network device may send (e.g., scan) one or more SSBs within an SSB burst set (e.g., for RSRP measurement), and the WTRU may perform beam inference based on the received SSBs, such as Figure 6 shown.

[0123] Fig.14 An example of performing beam inference at a WTRU during an initial access phase is shown. As shown, the network device may perform an SSB beam (e.g., wide beam) scan within an SSB burst set (e.g., M SSB transmissions within the SSB burst set may be assumed), and the WTRU may use one or more SSB RSRP measurements or received SSB signals as input to beam inference. Based on the results of the beam inference, the WTRU may determine the best SSB (e.g., indicated by an SSB ID) or a sub-beam associated with the SSB, and select a RACH transmission opportunity for performing a PRACH procedure (e.g., a two-step or four-step RACH procedure).

[0124] If the WTRU supports beam inference during the initial access phase, the network device may broadcast support information, such as spatial information about the beam or sub-beam, for example as part of system information that the WTRU may receive via a broadcast channel, or using a predefined table or codebook that the WTRU may receive as part of configuration information (e.g., RRC configuration information). The network device may allocate additional RACH opportunities to support beam inference at the WTRU.

[0125] The WTRU may send a PRACH message in a random access opportunity (RO). The WTRU and / or the network device may determine the RACH resources based on the SSB ID, which may be obtained as a result of beam inference at the WTRU. The PRACH transmit beam may be based on the SSB (e.g., wide beam) or a narrow beam that may be QCL with the SSB. The network device may allocate additional PRACH resources for sub-beam indication, such as Fig.14For example, the network device may allocate additional PRACH resources (e.g., Fig.15 The allocated PRACH resources may be combined in the frequency domain with the PRACH resources for the SSB beam (e.g., Fig.15 The PRACH resource (0,0) shown is multiplexed.

[0126] The WTRU may use the same preamble for PRACH transmissions with multiple (e.g., all) reserved PRACH resources with the same SSB ID. Fig.15 As shown, PRACH resources (0,0), (1,1) and (1,2) for SSB ID #m can use the same PRACH preamble. Configuration parameters (e.g., such as msg1-FDM-sub, which can be set to 2, such as Fig.15 As shown) can be used to reserve additional PRACH subbeam resources (e.g., (1,1) and (1,2)) for SSB ID #m.

[0127] If the network device successfully receives the PRACH, the network device may perform a PDCCH transmission using the predicted narrow beam from the WTRU, which the WTRU may monitor as a PRACH response. The WTRU may use the TxPRACH beam space information as an Rx beam for reception (e.g., Fig.14 (as shown in (c)).

[0128] For example, in the RRC connected state, one or more of the following may be performed. For example, after completing the initial access procedure described herein, the WTRU may enter the RRC connected state. Since beam inference may have been performed at the WTRU during the initial access phase, the inferred beam may be applied to the PDCCH and / or PDSCH transmissions specific to the WTRU. The network device may enhance the inferred beam (e.g., further refine the beam) or perform beam tracking. The WTRU may perform one or more of the following beam management operations associated with beam inference at the WTRU, such as: Fig.16As shown. The network device may configure the WTRU with multiple CSI-RS resource sets and multiple NZP CSI-RS resources for each CSI resource set. The network device may also perform partial CSI-RS beam scanning, and the WTRU may measure one or more of the configured NZP CSI-RS resources (e.g., based on semi-persistent CSI RS transmission and reporting). The WTRU may perform beam inference based on the measurement results (e.g., L1-RSRP value) and / or the received CSI-RS reference signal (e.g., one or more CSI-RS ports).

[0129] The WTRU may report the CSI resource set ID (e.g., as a hierarchical beam level indication), codeword ID (e.g., via PMI format (i1, i2) and / or as a beam indication) and / or (predicted) RSRP to the network device (e.g., if hierarchicalBeamMapping is set to ON). The WTRU may report both predicted Tx and Rx beam / codeword IDs, or only Tx beam / codeword IDs, or only Rx beam / codeword IDs. If hierarchicalBeamMapping is set to OFF, the WTRU may report / feed back the angle of arrival (AoA) as auxiliary information to the network device. The reporting of AoA may be configured and / or enabled separately, e.g., independent of the CSI configuration. The AoA information may be considered as an Rx beam direction report.

[0130] The network device may configure aperiodic CSI reporting (e.g., based on aperiodic transmission of CSI reference signals) for the WTRU to verify one or more DL Tx beams. This may be because the DL Tx beam ultimately used by the network may be different from the beam inferred or predicted by the WTRU. If the predicted reference signal or beam performance is poor (e.g., below a performance threshold), the network device may switch back to using conventional beam management techniques (e.g., based on hierarchical beam searching).

[0131] Fig.17 An example of CSI resource configuration information (e.g., CSI-ResourceConfig) and beam management associated with H-MIMO when beam inference is performed at the WTRU, for example, when the WTRU is in an RRC connected state. Fig.17As shown, a network device such as a base station can configure multiple CSI resource sets (e.g., #2 and #3, assuming that #1 is the lowest CSI-RS resource set or CSI SSB resource set ID) in a CSI resource configuration for a CSI report (e.g., an L1-RSRP report). The network device can configure a first CSI-RS resource set (e.g., set #2) with 14 NZP CSI-RS resources for beam inference, and a second CSI-RS resource set (e.g., set #3) with 4 NZP CSI-RS resources for beam selection. The network device can send a partial set of CSI-RS beams. For example, in a beam inference monitoring period, the network device may, for example, send one or more level 2 (narrow) beams based on codebook indices {(2,2), (2,7), ..., (8,6)}. The level 2 beam can be mapped to the CSI-RS resources in CSI-RS resource set #2 (e.g., 14 CSI-RS resources). The network device may not inform the WTRU of the actual Tx (e.g., DFT) beam information. One or more (e.g., each) CSI-RS resources in the higher level CSI-RS set may be QCLed with the SSB index of CSI-RS set #1 (e.g., level 1 beam). The WTRU may measure the CSI-RS resources in CSI-RS resource set #2 and may use the measurement results as an input metric for beam inference at the WTRU. The WTRU may predict one or more narrow beams or refined beams. In some cases (e.g., if hierarchicalBeamMapping is set to ON), the WTRU may report the CSI-RS resource set ID, the predicted codeword ID (e.g., in PMI format (i1, i2)) and / or the measurement results (e.g., RSRP value) to the network device (e.g., when predicting a narrow beam or a refined beam). The WTRU may report both the predicted Tx and Rx beam / codeword IDs, or only the Tx beam / codeword ID, or only the Rx beam / codeword ID. The WTRU may also report RSRP (e.g., predicted RSRP) to the network device. In some cases (e.g., if hierarchicalBeamMapping is set to OFF), the WTRU may report the angle of arrival (AoA) to the network device (e.g., because there may be no GoB spatial information that the network device can refer to). CSI reporting may be performed via PUCCH or PUSCH, and / or based on the WTRU's reporting configuration (e.g., semi-persistent CSI reporting).Since the beam predicted by the WTRU may not be among the measured CSI-RS resources in the CSI-RS resource set, the WTRU may signal the predicted or inferred beam to the network device based on the beam grid configured in the spatial domain or via a non-grid based AoA reported to the network device (e.g., the network device may convert the AoA to spatial information). The AoA information may be considered as an Rx beam direction report. The network device may schedule non-periodic CSI-RS reporting for the WTRU to verify the preferred beam, such as. Fig.17 As shown, the CSI-RS resources in a resource set (eg, set #3) may be configured with CQI / PMI / RI to facilitate direct PDSCH transmission.

[0132] In an embodiment of the present disclosure, beam management and / or beam inference associated with H-MIMO may be performed at a network device (e.g., a base station or gNB). If the WTRU is in an initial access phase, the WTRU may report the best or highest q SSBs based on the measurement of the SSBs (e.g., L1-RSRP measurement), and the measurement results (e.g., L1-RSRP of the SSBs) and / or the corresponding SSB index in the PUSCH payload (e.g., msg-B in a two-step RACH process or msg3 in a four-step RACH process).

[0133] If the WTRU is in an RRC connected state, the network device may configure multiple CSI-RS resource sets and multiple NZP CSI-RS resources for each CSI resource set for the WTRU to perform CSI reporting (e.g., L1-RSRP CSI reporting). The reported CSI information may be used by the network device as input for beam inference. The network device may perform partial CSI-RS beam scanning, and the WTRU may measure one or more configured NZP CSI-RS resources (e.g., based on semi-persistent CSI reporting) and report the measurement results (e.g., L1-RSRP values) and / or corresponding CRI to the network device. The network device may perform beam inference based on the measurements reported by the WTRU (e.g., L1-RSRP values). The network device may configure aperiodic CSI reporting for the WTRU to verify one or more beams inferred or predicted by the network device. In some cases (e.g., if hierarchicalBeamMapping is set to ON), the network device may signal a codebook (e.g., 2D-DFT codebook) index to the WTRU (e.g., to identify the inferred beam) and may set the repeat flag for CSI-RS to ON so that the WTRU performs Rx beamforming. In some cases (e.g., if hierarchicalBeamMapping is set to OFF), the network device may perform (e.g., fall back to) beam scanning for the predicted beams and the WTRU may report measurements (e.g., L1-RSRP values) of those scanned beams to the network device. The network device may set the repeat flag to ON so that the WTRU performs Rx beamforming.

[0134] In an embodiment of the present disclosure, beam management and / or beam inference associated with H-MIMO may be performed at the WTRU. If the WTRU is in an initial access phase, a network device (e.g., a base station or gNB) may perform an SSB (e.g., wide beam) scan in an SSB burst set (e.g., M SSBs may be sent in an SSB burst set). The WTRU may select multiple SSB RSRPs (or received SSB signals) as input to beam inference at the WTRU.

[0135] Based on the results of the beam inference, the WTRU may determine the best SSB (e.g., indicated by the SSB ID) or sub-beams associated with the SSB. The WTRU may select a RACH transmission opportunity for performing a PRACH procedure (e.g., a two-step or four-step RACH procedure). If the network device supports WTRU beam inference during the initial access phase, the network device may broadcast support information, such as sub-beam spatial information, as part of the system information that the WTRU may receive via a broadcast channel, or using a predefined table or codebook that the WTRU may receive as part of the WTRU's configuration information. The network device may allocate additional RACH opportunities to facilitate beam inference at the WTRU.

[0136] If the network device successfully receives the PRACH, the network device may use a narrow beam (e.g., a predicted narrow beam) for PDCCH transmission and the WTRU may monitor the PDCCH transmission as a PRACH response. The WTRU may use the reported Tx PRACH beam space information to determine the Rx beam for reception.

[0137] While the WTRU is in an RRC connected state, the network device may configure the WTRU with multiple CSI-RS resource sets and multiple NZP CSI-RS resources for each CSI resource set to perform CSI measurements (e.g., L1-RSRP measurements) and / or reporting. The network device may perform partial CSI-RS beam scanning. In response, the WTRU may measure one or more of the CSI-RS resources, such as the NZP CSI-RS resources configured by the network device (e.g., based on a semi-persistent CSI reporting configuration), and the WTRU may perform beam inference based on the measurement results (e.g., RSRP values) and / or the received CSI-RS signals (e.g., CSI-RS ports and / or other CSI estimates associated with the CSI-RS signals). If beam inference is enabled on the WTRU side, the network device may configure a type of CSI reporting for the WTRU. With this type of CSI reporting, the WTRU may not report measurement results such as RSRP results (e.g., L1-RSRP) and may report one or more inferred or predicted beams. The network device may configure one or more NZP CSI-RS resource sets and / or one or more CSI-RS resources per resource set for the WTRU to report the predicted beam. In some cases (e.g., if hierarchicalBeamMapping is set to ON), the WTRU may report the CSI resource set ID (e.g., for beam hierarchical level indication), CSI-RS resource ID (e.g., for beam inference) and / or codebook ID (e.g., in PMI format (i1, i2)) to the network device. In some examples, the network device may request the WTRU to report the predicted beam along with the measurement results (e.g., RSRP value). In some cases (e.g., if hierarchicalBeamMapping is set to OFF), the WTRU may report the angle of arrival (AoA) to the network device. The network device may (e.g., after the network device receives feedback from the WTRU) configure aperiodic CSI reporting for the WTRU to verify one or more DL Tx beams. Even if the WTRU performs beam inference, the network device may decide to use traditional beam management (e.g., fall back to beam scanning).

[0138] Fig.18An example of a hierarchical beam structure (e.g., a hierarchical spatial arrangement of beams) that may be used in an H-MIMO system is shown. As shown, a network device may configure a WTRU with multiple groups of beams (e.g., with respective spatial resolutions) and may indicate these groups of beams (e.g., together with their spatial arrangement) to the WTRU as part of the WTRU's configuration information (e.g., which may be transmitted to the WTRU via one or more RRC messages). For example, the configuration information may indicate the number of beams included in each group of beams and the hierarchical relationship of these groups of beams (e.g., beams associated with a lower beam level in the hierarchical arrangement may be QCLed with beams at a higher beam level). The configuration information may include a corresponding codebook associated with the level or group of beams, and the WTRU may use the codebook to determine the hierarchical structure or arrangement of beams and / or identify a particular beam (e.g., based on an index, such as a codeword index associated with the codebook).

[0139] Fig.19 Example operations that may be associated with beam inference and / or beam management performed by a network device (e.g., a base station or gNB) and / or a WTRU are shown. Fig.19 As shown, the network device may send one or more beams to the WTRU, for example, during a training period. The network device may indicate the one or more selected beams to the WTRU, for example, by indicating to the WTRU the corresponding codeword identifier (ID) of the codebook associated with the selected beam. The codebook and / or codeword ID may be pre-indicated to the WTRU as part of the WTRU's configuration information (e.g., configuration information that may indicate a hierarchical arrangement of beams, as described herein). In an example, if the codebook is associated with the same spatial resolution (e.g., beam resolution) as a previous codebook (e.g., a codebook associated with a beam predicted by the WTRU or indicated by the WTRU), the network device may not signal the codebook ID again; otherwise, the network device may signal the ID of the newly selected codebook. In response to the beams and / or other indications sent by the network device, the WTRU may measure the beams (Tx beams) and report one or more top-ranked Tx beams (e.g., and measurement results associated with those beams) to the network device. The WTRU may also report to the network device one or more Rx beams predicted by the WTRU.

[0140] Based on the WTRU's report, the network device may determine / select one or more beams (e.g., the best Tx beam) for the WTRU. The network device also determines whether to perform (e.g., fall back to) beam scanning on the determined beam. If the network device determines to perform beam scanning, the WTRU may determine the best Tx-Rx beam pair based on the scanned beams, and may report the determined Tx-Rx beam pair to the network device. If the network device determines not to perform beam scanning, the network device may indicate to the WTRU the beams selected by the network device and / or the CSI-RS resources associated with those beams, as well as other auxiliary information (e.g., codebook index, probability indicating the likelihood of predicting the beam, etc.). The network device may indicate the selected beams to the WTRU, for example, by indicating to the WTRU the corresponding codeword IDs associated with those beams. If the network device determines that the codebook associated with the selected beam has a spatial resolution (e.g., beam resolution) that is different from the spatial resolution of the previous codebook, the network device may also signal the newly selected codebook ID to the WTRU.

[0141] In response to receiving an indication of a selected beam and / or codebook / codeword ID, the WTRU may determine a Tx beam and / or Rx beam for the WTRU using spatial information associated with the selected beam (e.g., spatial information that the WTRU may have previously received via configuration information). The WTRU may then report the determined Tx and / or Rx beams to the network device (e.g., as a Tx-Rx beam pair).

[0142] Although the features and elements described above are described in particular combinations, each feature or element may be used alone without the other features and elements of the preferred embodiments, or in various combinations with or without the other features and elements.

[0143] Although the implementation described herein may consider 3GPP specific protocols, it should be understood that the implementation described herein is not limited to such scenarios and is applicable to other wireless systems. For example, although the solution described herein considers LTE, LTE-A, New Radio (NR) or 5G specific protocols, it should be understood that the solution described herein is not limited to such scenarios and is also applicable to other wireless systems.

[0144] The processes described above may be implemented in a computer program, software, and / or firmware incorporated in a computer-readable medium for execution by a computer and / or processor. Examples of computer-readable media include, but are not limited to, electronic signals (sent via wired and / or wireless connections) and / or computer-readable storage media. Examples of 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, but not limited to, built-in hard disks and removable disks), magneto-optical media, and / or optical media (such as compact disk (CD)-ROM disks and / or digital versatile disks (DVDs)). A processor associated with the software may be used to implement a radio frequency transceiver for a WTRU, terminal, base station, RNC, and / or any host computer.

Claims

1. A wireless transmit / receive unit (WTRU), the wireless transmit / receive unit (WTRU) comprising: A processor, the processor being configured to: receiving configuration information from a network device, wherein the configuration information indicates a hierarchical spatial arrangement of at least a first plurality of beams and a second plurality of beams, the first plurality of beams being associated with a first spatial resolution, the second plurality of beams being associated with a second spatial resolution, and an area covered by one of the first plurality of beams encompassing an area covered by one of the second plurality of beams; performing measurements of beams belonging to the first plurality of beams or the second plurality of beams; sending a report of the measurement of the beam to the network device; determining a transmit beam to be used by the WTRU based on the configuration information and a beam indication received from the network device after the sending of the report; and Transmission is performed using the transmission beam.

2. The WTRU of claim 1 , wherein: The beam measured by the WTRU is one of the first plurality of beams, and wherein the transmit beam is one of the second plurality of beams.

3. The WTRU of claim 1 , wherein: The processor is further configured to make a prediction regarding the transmit beam based on the configuration information received from the network device and the measurements performed by the WTRU, and to send an indication of the prediction to the network device.

4. The WTRU of claim 3, wherein: The processor being configured to make the prediction regarding the transmit beam includes the processor being configured to predict that the transmit beam to be used by the WTRU is narrower than a beam measured by the WTRU.

5. The WTRU of claim 3, wherein: The processor is further configured to include the indication of the prediction in the report sent to the network device.

6. The WTRU of claim 1 , wherein: The configuration information includes a first codebook associated with the first plurality of beams and a second codebook associated with the second plurality of beams, and wherein the beam indication received from the network device includes an index identifying the transmit beam in the first codebook or the second codebook.

7. The WTRU of claim 1 , wherein: The configuration information also indicates a first channel state information reference signal (CSI-RS) resource set associated with the first plurality of beams and a second CSI-RS resource set associated with the second plurality of beams, and wherein the measurement of the beam is performed using CSI-RS resources from the first CSI-RS resource set or the second CSI-RS resource set.

8. The WTRU of claim 1 , wherein: The processor is further configured to predict a receive beam based at least on the configuration information received from the network device and the measurements performed by the WTRU.

9. The WTRU of claim 8, wherein: The processor is further configured to include an indication of the predicted receive beam in the report sent to the network device.

10. The WTRU of claim 9, wherein: The configuration information received from the network device includes a codebook associated with the first plurality of beams or the second plurality of beams, and wherein the predicted receive beam is indicated via a codeword index associated with the codebook.

11. A method implemented by a wireless transmit / receive unit (WTRU), the method comprising: receiving configuration information from a network device, wherein the configuration information indicates a hierarchical spatial arrangement of at least a first plurality of beams and a second plurality of beams, the first plurality of beams being associated with a first spatial resolution, the second plurality of beams being associated with a second spatial resolution, and an area covered by one of the first plurality of beams encompassing an area covered by one of the second plurality of beams; performing measurements of beams belonging to the first plurality of beams or the second plurality of beams; sending a report of the measurement of the beam to the network device; determining a transmit beam to be used by the WTRU based on the configuration information and a beam indication received from the network device after the sending of the report; and Transmission is performed using the transmission beam.

12. The method according to claim 11, wherein: The beam measured by the WTRU is one of the first plurality of beams, and wherein the transmit beam is one of the second plurality of beams.

13. The method of claim 11, further comprising making a prediction about the transmit beam based on the configuration information received from the network device and the measurements performed by the WTRU, and indicating the prediction in the report sent to the network device.

14. The method according to claim 11, wherein: The configuration information includes a first codebook associated with the first plurality of beams and a second codebook associated with the second plurality of beams, and wherein the beam indication received from the network device includes an index identifying the transmit beam in the first codebook or the second codebook.

15. The method according to claim 11, wherein: The configuration information also indicates a first channel state information reference signal (CSI-RS) resource set associated with the first plurality of beams and a second CSI-RS resource set associated with the second plurality of beams, and wherein the measurement of the beam is performed using CSI-RS resources from the first CSI-RS resource set or the second CSI-RS resource set.

16. The method according to claim 11, further comprising: A receive beam is predicted based at least on the configuration information received from the network device, and the predicted receive beam is indicated in the report sent to the network device.

17. A network device, comprising: A processor, the processor being configured to: sending configuration information to a wireless transmit / receive unit (WTRU), wherein the configuration information indicates a hierarchical spatial arrangement of at least a first plurality of beams and a second plurality of beams, the first plurality of beams being associated with a first spatial resolution, the second plurality of beams being associated with a second spatial resolution, and an area covered by one of the first plurality of beams encompassing an area covered by one of the second plurality of beams; receiving a report from the WTRU regarding beams measured by the WTRU, wherein the beam belongs to the first plurality of beams or the second plurality of beams; determining a transmit beam to be used by the WTRU based at least on the report; and A message is sent to the WTRU, wherein the message indicates the transmit beam to be used by the WTRU.

18. The network device according to claim 17, wherein: The beam measured by the WTRU is one of the first plurality of beams, and wherein the transmit beam determined by the network device is one of the second plurality of beams.

19. The network device of claim 17, the processor being configured to determine the transmit beam further based on a prediction made by the WTRU and indicated in the report.

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