EP4792554A1 - Ris discovery and service - Google Patents

Abstract

Systems, methods, and instrumentalities for RIS discovery are disclosed. A WTRU may receive information associated with one or more Reflective Intelligent Surfaces/Reconfigurable Intelligent Surfaces (RISs) that may be available for communication with the WTRU. The WTRU may send, based on the received information, a request to initiate discovery to one or more of the RISs. The WTRU may receive at least one response message wherein the at least one response message may identify at least one available RIS. The WTRU may send a request for service to the at least one available RIS. The WTRU may receive scheduling information associated with the at least one available RIS and may transmit, based on the scheduling information, RIS-based communication to the at least one available RIS.

Description

RIS DISCOVERY AND SERVICE

CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims the benefit of US patent application number 63/543,786 filed October 12, 2023, the contents of which are hereby incorporated by reference herein in its entirety.

BACKGROUND

[0002] Mobile communications using wireless communication continue to evolve. A fifth generation may be referred to as 5G. A previous (legacy) generation of mobile communication may be, for example, fourth generation (4G) long term evolution (LTE).

SUMMARY

[0003] Systems, methods, and instrumentalities are described that may be associated with RIS (Reflective Intelligent Surface/Reconfigurable Intelligent Surface) discovery.

[0004] A wireless transmit and receive unit (WTRU) may send a request regarding availability of RISs for communication with the WTRU. The WTRU may receive, in response to the request, in a downlink transmission, e.g., PDSCH transmission, information associated with available Reflective Intelligent Surfaces (RISs) available for communication with the WTRU. The received information associated with the available RISs may comprise, for example, at least one of a number of deployed RISs, RIS type, RIS mode, RIS phase resolution, RIS codebooks, RIS orientation, sub-surface grouping, or RIS area with increased near field effects.

[0005] The WTRU may send, based on the received information, a request to initiate discovery of one or more of the available RISs. The request to initiate discovery may be sent via an uplink transmission, e.g., PUSCH transmission, and may comprise, for example, of one or more of a traffic type, an expected reliability, a buffer size, an indication of primary use, an indication of previously used RISs, or location information associated with the WTRU.

[0006] The WTRU may receive via a downlink transmission, e.g., PDSCH transmission, at least one response message comprising, for example, an indication of a number of RISs, RIS identifiers, a number of sub surfaces, frequency resources, near field information, and a type of RIS discovery. The at least one response message may further comprise at least one of a time resource, port information, hopping pattern, repetition factor, spatial filter information, or time transmission properties.

[0007] The WTRU may, on a condition that the type of RIS discovery is associated with downlink, perform a measurement for a configured reception occasion, report an index associated with the measurement, and receive an identifier associated with a RIS. The identifier associated with the RIS may comprise an implicit indication of the RIS.

[0008] The WTRU may, on a condition that the type of RIS discovery is associated with uplink, transmit an uplink reference signal, and receive an indication of one or more RISs.

[0009] The WTRU may send a request for service from at least one of the available RISs. The request for service may comprise one or more of an identifier associated with the at least one of the available RISs, configuration information for the at least one of the available RISs, or resource requirements.

[0010] The WTRU may receive scheduling information associated with the at least one of the available RISs. The WTRU may transmit, based on the scheduling information, RIS-based communication to the at least one of the available RISs.

[0011] In examples, a wireless transmit and receive unit (WTRU) may receive information associated with one or more RISs that may be available for communication with the WTRU. The received information may identify a number of deployed RISs and information associated with the deployed RISs such as, for example, RIS type, RIS mode, RIS phase resolution, RIS codebooks, RIS orientation, location within a cell, groupings, etc.

[0012] The WTRU may send, based on the received information, a request to initiate discovery to one or more of the RISs. The request may be carried on an uplink transmission and may comprise, for example, an indication of a traffic type, reliability, buffer size, intended usage, identifiers associated with RISs previously used, and/or location of the WTRU.

[0013] The WTRU may receive at least one response message wherein the at least one response message may identify at least one available RIS. The response message may comprise at least one of a type of discovery process associated with the at least one available RIS, a time resource, frequency source, port information, hopping pattern, repetition factor, spatial filter information, time transmission properties, an identifier, a number of available RIS units, or near field information.

[0014] The WTRU may determine, on a condition that the at least one response message comprises a downlink reference signal, to: perform a measurement of a configured reception occasion; report one or more indices associated with the measurement; and receive one or more identifiers associated with identified RIS units. [0015] The WTRU may send a request for service to the at least one available RIS. The request for service may comprise one or more of an identifier associated with the at least one available RIS, configuration information for the at least one available RIS, and resource requirements.

[0016] The WTRU may receive scheduling information associated with the at least one available RIS and may transmit, based on the scheduling information, RIS-based communication to the at least one available RIS.

BRIEF DESCRIPTION OF THE DRAWINGS

[0017] FIG. 1A is a system diagram illustrating an example communications system in which one or more disclosed embodiments may be implemented.

[0018] FIG. 1 B is a system diagram illustrating an example wireless transmit/receive unit (WTRU) that may be used within the communications system illustrated in FIG. 1A according to an embodiment.

[0019] FIG. 1C is a system diagram illustrating an example radio access network (RAN) and an example core network (ON) that may be used within the communications system illustrated in FIG. 1 A according to an embodiment.

[0020] FIG. 1 D is a system diagram illustrating a further example RAN and a further example ON that may be used within the communications system illustrated in FIG. 1A according to an embodiment.

[0021] FIG. 2 depicts an example RIS comprising a RIS controller and RIS panel.

[0022] FIG. 3 depicts an example RIS architecture.

[0023] FIG. 4 depicts an example multi-RIS deployment.

[0024] FIG. 5 depicts an example RIS-aided system.

[0025] FIG. 6 depicts an example signal flow chart.

DETAILED DESCRIPTION

[0026] A more detailed understanding may be had from the following description, given by way of example in conjunction with the accompanying drawings.

[0027] FIG. 1A is a diagram illustrating an example communications system 100 in which one or more disclosed embodiments may be implemented. The communications system 100 may be a multiple access system that provides content, such as voice, data, video, messaging, broadcast, etc., to multiple wireless users. The communications system 100 may enable multiple wireless users to access such content through the sharing of system resources, including wireless bandwidth. For example, the communications systems 100 may employ one or more channel access methods, such as code division multiple access (CDMA), time division multiple access (TDMA), frequency division multiple access (FDMA), orthogonal FDMA (OFDMA), single-carrier FDMA (SC-FDMA), zero-tail unique-word discrete Fourier transform (DFT)- Spread OFDM (ZT UW DTS-s OFDM), unique word OFDM (UW-OFDM), resource block-filtered OFDM, filter bank multicarrier (FBMC), and the like.

[0028] As shown in FIG. 1A, the communications system 100 may include wireless transmit/receive units (WTRUs) 102a, 102b, 102c, 102d, a RAN 104/113, a ON 106/115, a public switched telephone network (PSTN) 108, the Internet 110, and other networks 112, though it will be appreciated that the disclosed embodiments contemplate any number of WTRUs, base stations, networks, and/or network elements. Each of the WTRUs 102a, 102b, 102c, 102d may be any type of device configured to operate and/or communicate in a wireless environment. By way of example, the WTRUs 102a, 102b, 102c, 102d, any of which may be referred to as a “station” and/or a “ST A”, may be configured to transmit and/or receive wireless signals and may include a user equipment (UE), a mobile station, a fixed or mobile subscriber unit, a subscription-based unit, a pager, a cellular telephone, a personal digital assistant (PDA), a smartphone, a laptop, a netbook, a personal computer, a wireless sensor, a hotspot or Mi-Fi device, an Internet of Things (loT) device, a watch or other wearable, a head-mounted display (HMD), a vehicle, a drone, a medical device and applications (e.g., remote surgery), an industrial device and applications (e.g., a robot and/or other wireless devices operating in an industrial and/or an automated processing chain contexts), a consumer electronics device, a device operating on commercial and/or industrial wireless networks, and the like. Any of the WTRUs 102a, 102b, 102c, and 102d may be interchangeably referred to as a UE.

[0029] The communications systems 100 may also include a base station 114a and/or a base station 114b. Each of the base stations 114a, 114b may be any type of device configured to wirelessly interface with at least one of the WTRUs 102a, 102b, 102c, 102d to facilitate access to one or more communication networks, such as the CN 106/115, the Internet 110, and/or the other networks 112. By way of example, the base stations 114a, 114b may be a base transceiver station (BTS), a Node-B, an eNode B (eNB), a Home Node B, a Home eNode B, a gNode B (gNB), a NR NodeB, a site controller, an access point (AP), a wireless router, and the like. While the base stations 114a, 114b are each depicted as a single element, it will be appreciated that the base stations 114a, 114b may include any number of interconnected base stations and/or network elements.

[0030] The base station 114a may be part of the RAN 104/113, which may also include other base stations and/or network elements (not shown), such as a base station controller (BSC), a radio network controller (RNC), relay nodes, etc. The base station 114a and/or the base station 114b may be configured to transmit and/or receive wireless signals on one or more carrier frequencies, which may be referred to as a cell (not shown). These frequencies may be in licensed spectrum, unlicensed spectrum, or a combination of licensed and unlicensed spectrum. A cell may provide coverage for a wireless service to a specific geographical area that may be relatively fixed or that may change over time. The cell may further be divided into cell sectors. For example, the cell associated with the base station 114a may be divided into three sectors. Thus, in one embodiment, the base station 114a may include three transceivers, i.e., one for each sector of the cell. In an embodiment, the base station 114a may employ multiple-input multiple output (MIMO) technology and may utilize multiple transceivers for each sector of the cell. For example, beamforming may be used to transmit and/or receive signals in desired spatial directions.

[0031] 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).

[0032] More specifically, as noted above, the communications system 100 may be a multiple access system and may employ one or more channel access schemes, such as CDMA, TDMA, FDMA, OFDMA, SC-FDMA, and the like. For example, the base station 114a in the RAN 104/113 and the WTRUs 102a, 102b, 102c may implement a radio technology such as Universal Mobile Telecommunications System (UMTS) Terrestrial Radio Access (UTRA), which may establish the air interface 115/116/117 using wideband CDMA (WCDMA). WCDMA may include communication protocols such as High-Speed Packet Access (HSPA) and/or Evolved HSPA (HSPA+). HSPA may include High-Speed Downlink (DL) Packet Access (HSDPA) and/or High-Speed UL Packet Access (HSUPA).

[0033] In an embodiment, the base station 114a and the WTRUs 102a, 102b, 102c may implement a radio technology such as Evolved UMTS Terrestrial Radio Access (E-UTRA), which may establish the air interface 116 using Long Term Evolution (LTE) and/or LTE-Advanced (LTE-A) and/or LTE-Advanced Pro (LTE-A Pro).

[0034] 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).

[0035] In an embodiment, the base station 114a and the WTRUs 102a, 102b, 102c may implement multiple radio access technologies. For example, the base station 114a and the WTRUs 102a, 102b, 102c may implement LTE radio access and NR radio access together, for instance using dual connectivity (DC) principles. Thus, the air interface utilized by WTRUs 102a, 102b, 102c may be characterized by multiple types of radio access technologies and/or transmissions sent to/from multiple types of base stations (e.g., an eNB and a gNB).

[0036] 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), GSM EDGE (GERAN), and the like.

[0037] The base station 114b in FIG. 1 A may be a wireless router, Home Node B, Home eNode B, or access point, for example, and may utilize any suitable RAT for facilitating wireless connectivity in a localized area, such as a place of business, a home, a vehicle, a campus, an industrial facility, an air corridor (e.g., for use by drones), a roadway, and the like. In 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 femtocell. As shown in FIG. 1 A, the base station 114b may have a direct connection to the Internet 110. Thus, the base station 114b may not be required to access the Internet 110 via the CN 106/115.

[0038] The RAN 104/113 may be in communication with the CN 106/115, which may be any type of network configured to provide voice, data, applications, and/or voice over internet protocol (VoIP) services to one or more of the WTRUs 102a, 102b, 102c, 102d. The data may have varying quality of service (QoS) requirements, such as differing throughput requirements, latency requirements, error tolerance requirements, reliability requirements, data throughput requirements, mobility requirements, and the like. The CN 106/115 may provide call control, billing services, mobile location-based services, pre-paid calling, Internet connectivity, video distribution, etc., and/or perform high-level security functions, such as user authentication. Although not shown in FIG. 1A, it will be appreciated that the RAN 104/113 and/or the CN 106/115 may be in direct or indirect communication with other RANs that employ the same RAT as the RAN 104/113 or a different RAT. For example, in addition to being connected to the RAN 104/113, which may be utilizing a NR radio technology, the CN 106/115 may also be in communication with another RAN (not shown) employing a GSM, UMTS, CDMA 2000, WiMAX, E-UTRA, or WiFi radio technology. [0039] The CN 106/115 may also serve as a gateway for the WTRUs 102a, 102b, 102c, 102d to access the PSTN 108, the Internet 110, and/or the other networks 112. The PSTN 108 may include circuit- switched telephone networks that provide plain old telephone service (POTS). The Internet 110 may include a global system of interconnected computer networks and devices that use common communication protocols, such as the transmission control protocol (TCP), user datagram protocol (UDP) and/or the internet protocol (IP) in the TCP/IP internet protocol suite. The networks 112 may include wired and/or wireless communications networks owned and/or operated by other service providers. For example, the networks 112 may include another CN connected to one or more RANs, which may employ the same RAT as the RAN 104/113 or a different RAT.

[0040] Some or all of the WTRUs 102a, 102b, 102c, 102d in the communications system 100 may include multi-mode capabilities (e.g., the WTRUs 102a, 102b, 102c, 102d may include multiple transceivers for communicating with different wireless networks over different wireless links). For example, the WTRU 102c shown in FIG. 1A may be configured to communicate with the base station 114a, which may employ a cellular-based radio technology, and with the base station 114b, which may employ an IEEE 802 radio technology.

[0041] FIG. 1 B is a system diagram illustrating an example WTRU 102. As shown in FIG. 1 B, the WTRU 102 may include 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, among others. It will be appreciated that the WTRU 102 may include any sub-combination of the foregoing elements while remaining consistent with an embodiment.

[0042] The processor 118 may be a general purpose processor, a special purpose processor, a conventional processor, a digital signal processor (DSP), a plurality of microprocessors, one or more microprocessors in association with a DSP core, a controller, a microcontroller, Application Specific Integrated Circuits (ASICs), Field Programmable Gate Arrays (FPGAs) circuits, any other type of integrated circuit (IC), a state machine, and the like. The processor 118 may perform signal coding, data processing, power control, input/output processing, and/or any other functionality that enables the WTRU 102 to operate in a wireless environment. The processor 118 may be coupled to the transceiver 120, which may be coupled to the transmit/receive element 122. While FIG. 1 B depicts the processor 118 and the transceiver 120 as separate components, it will be appreciated that the processor 118 and the transceiver 120 may be integrated together in an electronic package or chip. [0043] The transmit/receive element 122 may be configured to transmit signals to, or receive signals from, a base station (e.g., the base station 114a) over the air interface 116. For example, in one embodiment, the transmit/receive element 122 may be an antenna configured to transmit and/or receive RF signals. In an embodiment, the transmit/receive element 122 may be an emitter/detector configured to transmit and/or receive IR, UV, or visible light signals, for example. In yet another embodiment, the transmit/receive element 122 may be configured to transmit and/or receive both RF and light signals. It will be appreciated that the transmit/receive element 122 may be configured to transmit and/or receive any combination of wireless signals.

[0044] Although the transmit/receive element 122 is depicted in FIG. 1 B as a single element, 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.

[0045] The transceiver 120 may be configured to modulate the signals that are to be transmitted by the transmit/receive element 122 and to demodulate the signals that are received by the transmit/receive element 122. As noted above, the WTRU 102 may have multi-mode capabilities. Thus, the transceiver 120 may include multiple transceivers for enabling the WTRU 102 to communicate via multiple RATs, such as NR and IEEE 802.11 , for example.

[0046] The processor 118 of the WTRU 102 may be coupled to, and may receive user input data from, the speaker/microphone 124, the keypad 126, and/or the display/touchpad 128 (e.g., a liquid crystal display (LCD) display unit or organic light-emitting diode (OLED) display unit). The processor 118 may also output user data to the speaker/microphone 124, the keypad 126, and/or the display/touchpad 128. In addition, the processor 118 may access information from, and store data in, any type of suitable memory, such as the non-removable memory 130 and/or the removable memory 132. The non-removable memory 130 may include random-access memory (RAM), read-only memory (ROM), a hard disk, or any other type of memory storage device. The removable memory 132 may include a subscriber identity module (SIM) card, a memory stick, a secure digital (SD) memory card, and the like. In other embodiments, the processor 118 may access information from, and store data in, memory that is not physically located on the WTRU 102, such as on a server or a home computer (not shown).

[0047] The processor 118 may receive power from the power source 134 and may be configured to distribute and/or control the power to the other components in the WTRU 102. The power source 134 may be any suitable device for powering the WTRU 102. For example, the power source 134 may include one or more dry cell batteries (e.g., nickel-cadmium (NiCd), nickel-zinc (NiZn), nickel metal hydride (NiMH), lithium-ion (Li-ion), etc.), solar cells, fuel cells, and the like.

[0048] The processor 118 may also be coupled to the GPS chipset 136, which may be configured to provide location information (e.g., longitude and latitude) regarding the current location of the WTRU 102. In addition to, or in lieu of, the information from the GPS chipset 136, the WTRU 102 may receive location information over the air interface 116 from a base station (e.g., base stations 114a, 114b) and/or determine its location based on the timing of the signals being received from two or more nearby base stations. It will be appreciated that the WTRU 102 may acquire location information by way of any suitable locationdetermination method while remaining consistent with an embodiment.

[0049] The processor 118 may further be coupled to other peripherals 138, which may include one or more software and/or hardware modules that provide additional features, functionality and/or wired or wireless connectivity. For example, the peripherals 138 may include an accelerometer, an e-compass, a satellite transceiver, a digital camera (for photographs and/or video), a universal serial bus (USB) port, a vibration device, a television transceiver, a hands free headset, a Bluetooth® module, a frequency modulated (FM) radio unit, a digital music player, a media player, a video game player module, an Internet browser, a Virtual Reality and/or Augmented Reality (VR/AR) device, an activity tracker, and the like. The peripherals 138 may include one or more sensors, the sensors may be one or more of a gyroscope, an accelerometer, a hall effect sensor, a magnetometer, an orientation sensor, a proximity sensor, a temperature sensor, a time sensor; a geolocation sensor; an altimeter, a light sensor, a touch sensor, a magnetometer, a barometer, a gesture sensor, a biometric sensor, and/or a humidity sensor.

[0050] The WTRU 102 may include a full duplex radio for which transmission and reception of some or all of the signals (e.g., associated with particular subframes for both the 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 to reduce and or substantially eliminate self-interference via either hardware (e.g., a choke) or signal processing via a processor (e.g., a separate processor (not shown) or via processor 118). In an embodiment, the WRTU 102 may include a half-duplex radio for which transmission and reception of some or all of the signals (e.g., associated with particular subframes for either the UL (e.g., for transmission) or the downlink (e.g., for reception)).

[0051] FIG. 1 C is a system diagram illustrating the RAN 104 and the CN 106 according to an embodiment. As noted above, the RAN 104 may employ an E-UTRA radio technology to communicate with the WTRUs 102a, 102b, 102c over the air interface 116. The RAN 104 may also be in communication with the CN 106. [0052] The RAN 104 may include eNode-Bs 160a, 160b, 160c, though it will be appreciated that the RAN 104 may include any number of eNode-Bs while remaining consistent with an embodiment. The eNode-Bs 160a, 160b, 160c may each include one or more transceivers for communicating with the WTRUs 102a, 102b, 102c over the air interface 116. In one embodiment, the eNode-Bs 160a, 160b, 160c may implement MIMO technology. Thus, the eNode-B 160a, for example, may use multiple antennas to transmit wireless signals to, and/or receive wireless signals from, the WTRU 102a.

[0053] Each of the eNode-Bs 160a, 160b, 160c may be associated with a particular cell (not shown) and may be configured to handle radio resource management decisions, handover decisions, scheduling of users in the UL and/or DL, and the like. As shown in FIG. 1 C, the eNode-Bs 160a, 160b, 160c may communicate with one another over an X2 interface.

[0054] The CN 106 shown in FIG. 1 C may include a mobility management entity (MME) 162, a serving gateway (SGW) 164, and a packet data network (PDN) gateway (or PGW) 166. While each of the foregoing elements is depicted as part of the CN 106, it will be appreciated that any of these elements may be owned and/or operated by an entity other than the CN operator.

[0055] The MME 162 may be connected to each of the eNode-Bs 162a, 162b, 162c in the RAN 104 via an S1 interface and may serve as a control node. For example, the MME 162 may be responsible for authenticating users of the WTRUs 102a, 102b, 102c, bearer activation/deactivation, selecting a particular serving gateway during an initial attach of the WTRUs 102a, 102b, 102c, and the like. The MME 162 may provide a control plane function for switching between the RAN 104 and other RANs (not shown) that employ other radio technologies, such as GSM and/or WCDMA.

[0056] The SGW 164 may be connected to each of the eNode Bs 160a, 160b, 160c in the RAN 104 via the 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 user planes during inter- eNode B handovers, triggering paging when DL data is available for the WTRUs 102a, 102b, 102c, managing and storing contexts of the WTRUs 102a, 102b, 102c, and the like.

[0057] 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.

[0058] The CN 106 may facilitate communications with other networks. For example, the CN 106 may provide the WTRUs 102a, 102b, 102c with access to circuit-switched networks, such as the PSTN 108, to facilitate communications between the WTRUs 102a, 102b, 102c and traditional land-line communications devices. For example, the CN 106 may include, or may communicate with, an IP gateway (e.g., an IP multimedia subsystem (IMS) server) that serves as an interface between the CN 106 and the PSTN 108. In addition, the CN 106 may provide the WTRUs 102a, 102b, 102c with access to the other networks 112, which may include other wired and/or wireless networks that are owned and/or operated by other service providers.

[0059] Although the WTRU is described in FIGS. 1 A-1 D as a wireless terminal, it is contemplated that in certain representative embodiments that such a terminal may use (e.g., temporarily or permanently) wired communication interfaces with the communication network.

[0060] In representative embodiments, the other network 112 may be a WLAN.

[0061] A WLAN in Infrastructure Basic Service Set (BSS) mode may have an Access Point (AP) for the BSS and one or more stations (STAs) associated with the AP. The AP may have an access or an interface to a Distribution System (DS) or another type of wired/wireless network that carries traffic in to and/or out of the BSS. Traffic to STAs that originates from outside the BSS may arrive through the AP and may be delivered to the STAs. Traffic originating from STAs to destinations outside the BSS may be sent to the AP to be delivered to respective destinations. Traffic between STAs within the BSS may be sent through the AP, for example, where the source STA may send traffic to the AP and the AP may deliver the traffic to the destination STA. The traffic between STAs within a BSS may be considered and/or referred to as peer-to- peer traffic. The peer-to-peer traffic may be sent between (e.g., directly between) the source and destination STAs with a direct link setup (DLS). In certain representative embodiments, the DLS may use an 802.11e DLS or an 802.11 z tunneled DLS (TDLS). A WLAN using an Independent BSS (IBSS) mode may not have an AP, and the STAs (e.g., all of the STAs) within or using the IBSS may communicate directly with each other. The IBSS mode of communication may sometimes be referred to herein as an “ad-hoc” mode of communication.

[0062] When using the 802.11 ac infrastructure mode of operation or a similar mode of operations, the AP may transmit a beacon on a fixed channel, such as a primary channel. The primary channel may be a fixed width (e.g., 20 MHz wide bandwidth) or a dynamically set width via signaling. The primary channel may be the operating channel of the BSS and may be used by the STAs to establish a connection with the AP. In certain representative embodiments, Carrier Sense Multiple Access with Collision Avoidance (CSMA/CA) may be implemented, for example in in 802.11 systems. For CSMA/CA, the STAs (e.g., every STA), including the AP, may sense the primary channel. If the primary channel is sensed/detected and/or determined to be busy by a particular STA, the particular STA may back off. One STA (e.g., only one station) may transmit at any given time in a given BSS. [0063] High Throughput (HT) STAs may use a 40 MHz wide channel for communication, for example, via a combination of the primary 20 MHz channel with an adjacent or nonadjacent 20 MHz channel to form a 40 MHz wide channel.

[0064] Very High Throughput (VHT) STAs may support 20MHz, 40 MHz, 80 MHz, and/or 160 MHz wide channels. The 40 MHz, and/or 80 MHz, channels may be formed by combining contiguous 20 MHz channels. A 160 MHz channel may be formed by combining 8 contiguous 20 MHz channels, or by combining two non-contiguous 80 MHz channels, which may be referred to as an 80+80 configuration. For the 80+80 configuration, the data, after channel encoding, may be passed through a segment parser that may divide the data into two streams. Inverse Fast Fourier Transform (IFFT) processing, and time domain processing, may be done on each stream separately. The streams may be mapped on to the two 80 MHz channels, and the data may be transmitted by a transmitting STA. At the receiver of the receiving STA, the above described operation for the 80+80 configuration may be reversed, and the combined data may be sent to the Medium Access Control (MAC).

[0065] Sub 1 GHz modes of operation are supported by 802.11 af and 802.11 ah. The channel operating bandwidths, and carriers, are reduced in 802.11 af and 802.11 ah relative to those used in 802.11 n, and 802.11 ac. 802.11 af supports 5 MHz, 10 MHz and 20 MHz bandwidths in the TV White Space (TVWS) spectrum, and 802.11ah supports 1 MHz, 2 MHz, 4 MHz, 8 MHz, and 16 MHz bandwidths using non- TVWS spectrum. According to a representative embodiment, 802.11 ah may support Meter Type Control/Machine-Type Communications, such as MTC devices in a macro coverage area. MTC devices may have certain capabilities, for example, limited capabilities including support for (e.g., only support for) certain and/or limited bandwidths. The MTC devices may include a battery with a battery life above a threshold (e.g., to maintain a very long battery life).

[0066] WLAN systems, which may support multiple channels, and channel bandwidths, such as 802.11 n, 802.11 ac, 802.11 af, and 802.11 ah, include a channel which may be designated as the primary channel. The primary channel may have a bandwidth equal to the largest common operating bandwidth supported by all STAs in the BSS. The bandwidth of the primary channel may be set and/or limited by a STA, from among all STAs in operating in a BSS, which supports the smallest bandwidth operating mode. In the example of 802.11 ah, the primary channel may be 1 MHz wide for STAs (e.g., MTC type devices) that support (e.g., only support) a 1 MHz mode, even if the AP, and other STAs in the BSS support 2 MHz, 4 MHz, 8 MHz, 16 MHz, and/or other channel bandwidth operating modes. Carrier sensing and/or Network Allocation Vector (NAV) settings may depend on the status of the primary channel. If the primary channel is busy, for example, due to a STA (which supports (e.g., only supports) a 1 MHz operating mode), transmitting to the AP, the entire available frequency bands may be considered busy even though a majority of the frequency bands remains idle and may be available.

[0067] In the United States, the available frequency bands, which may be used by 802.11 ah, are from 902 MHz to 928 MHz. In Korea, the available frequency bands are from 917.5 MHz to 923.5 MHz. In Japan, the available frequency bands are from 916.5 MHz to 927.5 MHz. The total bandwidth available for 802.11 ah is 6 MHz to 26 MHz depending on the country code.

[0068] FIG. 1 D is a system diagram illustrating the RAN 113 and the CN 115 according to an embodiment. As noted above, the RAN 113 may employ an NR radio technology to communicate with the WTRUs 102a, 102b, 102c over the air interface 116. The RAN 113 may also be in communication with the CN 115.

[0069] The RAN 113 may include gNBs 180a, 180b, 180c, though it will be appreciated that the RAN 113 may include any number of gNBs while remaining consistent with an embodiment. The gNBs 180a, 180b, 180c may each include one or more transceivers for communicating with the WTRUs 102a, 102b, 102c over the air interface 116. In one embodiment, the gNBs 180a, 180b, 180c may implement MIMO technology. For example, gNBs 180a, 108b may utilize beamforming to transmit signals to and/or receive signals from the gNBs 180a, 180b, 180c. Thus, the gNB 180a, for example, may use multiple antennas to transmit wireless signals to, and/or receive wireless signals from, the WTRU 102a. In an embodiment, the gNBs 180a, 180b, 180c may implement carrier aggregation technology. For example, the gNB 180a may transmit multiple component carriers to the WTRU 102a (not shown). A subset of these component carriers may be on unlicensed spectrum while the remaining component carriers may be on licensed spectrum. In an embodiment, the gNBs 180a, 180b, 180c may implement Coordinated Multi-Point (CoMP) technology. For example, WTRU 102a may receive coordinated transmissions from gNB 180a and gNB 180b (and/or gNB 180c).

[0070] The WTRUs 102a, 102b, 102c may communicate with gNBs 180a, 180b, 180c using transmissions associated with a scalable numerology. For example, the OFDM symbol spacing and/or OFDM subcarrier spacing may vary for different transmissions, different cells, and/or different portions of the wireless transmission spectrum. The WTRUs 102a, 102b, 102c may communicate with gNBs 180a, 180b, 180c using subframe or transmission time intervals (TTIs) of various or scalable lengths (e.g., containing varying number of OFDM symbols and/or lasting varying lengths of absolute time).

[0071] The gNBs 180a, 180b, 180c may be configured to communicate with the WTRUs 102a, 102b, 102c in a standalone configuration and/or a non-standalone configuration. In the standalone configuration, WTRUs 102a, 102b, 102c may communicate with gNBs 180a, 180b, 180c without also accessing other RANs (e.g., such as eNode-Bs 160a, 160b, 160c). In the standalone configuration, WTRUs 102a, 102b, 102c may utilize one or more of gNBs 180a, 180b, 180c as a mobility anchor point. In the standalone configuration, WTRUs 102a, 102b, 102c may communicate with gNBs 180a, 180b, 180c using signals in an unlicensed band. In a non-standalone configuration WTRUs 102a, 102b, 102c may communicate with/connect to gNBs 180a, 180b, 180c while also communicating with/connecting to another RAN such as eNode-Bs 160a, 160b, 160c. For example, WTRUs 102a, 102b, 102c may implement DC principles to communicate with one or more gNBs 180a, 180b, 180c and one or more eNode-Bs 160a, 160b, 160c substantially simultaneously. In the non-standalone configuration, eNode-Bs 160a, 160b, 160c may serve as a mobility anchor for WTRUs 102a, 102b, 102c and gNBs 180a, 180b, 180c may provide additional coverage and/or throughput for servicing WTRUs 102a, 102b, 102c.

[0072] Each of the gNBs 180a, 180b, 180c may be associated with a particular cell (not shown) and may be configured to handle radio resource management decisions, handover decisions, scheduling of users in the UL and/or DL, support of network slicing, dual connectivity, interworking between NR and E- UTRA, routing of user plane data towards User Plane Function (UPF) 184a, 184b, routing of control plane information towards Access and Mobility Management Function (AMF) 182a, 182b and the like. As shown in FIG. 1 D, the gNBs 180a, 180b, 180c may communicate with one another over an Xn interface.

[0073] The CN 115 shown in FIG. 1 D may include at least one AMF 182a, 182b, at least one UPF 184a, 184b, at least one Session Management Function (SMF) 183a, 183b, and possibly a Data Network (DN) 185a, 185b. While each of the foregoing elements are depicted as part of the CN 115, it will be appreciated that any of these elements may be owned and/or operated by an entity other than the CN operator.

[0074] The AMF 182a, 182b may be connected to one or more of the gNBs 180a, 180b, 180c in the RAN 113 via an N2 interface and may serve as a control node. For example, the AMF 182a, 182b may be responsible for authenticating users of the WTRUs 102a, 102b, 102c, support for network slicing (e.g., handling of different PDU sessions with different requirements), selecting a particular SMF 183a, 183b, management of the registration area, termination of NAS signaling, mobility management, and the like. Network slicing may be used by the AMF 182a, 182b in order to customize CN support for WTRUs 102a, 102b, 102c based on the types of services being utilized WTRUs 102a, 102b, 102c. For example, different network slices may be established for different use cases such as services relying on ultra-reliable low latency (URLLC) access, services relying on enhanced massive mobile broadband (eMBB) access, services for machine type communication (MTC) access, and/or the like. 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. [0075] The SMF 183a, 183b may be connected to an AMF 182a, 182b in the CN 115 via an N11 interface. The SMF 183a, 183b may also be connected to a UPF 184a, 184b in the CN 115 via an N4 interface. The SMF 183a, 183b may select and control the UPF 184a, 184b and configure the routing of traffic through the UPF 184a, 184b. The SMF 183a, 183b may perform other functions, such as managing and allocating UE IP address, managing PDU sessions, controlling policy enforcement and QoS, providing downlink data notifications, and the like. A PDU session type may be IP-based, non-IP based, Ethernetbased, and the like.

[0076] The UPF 184a, 184b may be connected to one or more of the gNBs 180a, 180b, 180c in the RAN 113 via an N3 interface, which may provide the WTRUs 102a, 102b, 102c with access to packet- switched networks, such as the Internet 110, to facilitate communications between the WTRUs 102a, 102b, 102c and IP-enabled devices. The UPF 184, 184b may perform other functions, such as routing and forwarding packets, enforcing user plane policies, supporting multi-homed PDU sessions, handling user plane QoS, buffering downlink packets, providing mobility anchoring, and the like.

[0077] The CN 115 may facilitate communications with other networks. For example, the CN 115 may include, or may communicate with, an IP gateway (e.g., an IP multimedia subsystem (IMS) server) that serves as an interface between the CN 115 and the PSTN 108. In addition, the CN 115 may provide the WTRUs 102a, 102b, 102c with access to the other networks 112, which may include other wired and/or wireless networks that are owned and/or operated by other service providers. In one embodiment, the WTRUs 102a, 102b, 102c may be connected to a local Data Network (DN) 185a, 185b through the UPF 184a, 184b via the N3 interface to the UPF 184a, 184b and an N6 interface between the UPF 184a, 184b and the DN 185a, 185b.

[0078] In view of Figures 1A-1 D, and the corresponding description of Figures 1A-1 D, one or more, or all, of the functions described herein with regard to one or more of: WTRU 102a-d, Base Station 114a-b, eNode-B 160a-c, MME 162, SGW 164, PGW 166, gNB 180a-c, AMF 182a-b, UPF 184a-b, SMF 183a-b, DN 185a-b, and/or any other device(s) described herein, may be performed by one or more emulation devices (not shown). The emulation devices may be one or more devices configured to emulate one or more, or all, of the functions described herein. For example, the emulation devices may be used to test other devices and/or to simulate network and/or WTRU functions.

[0079] The emulation devices may be designed to implement one or more tests of other devices in a lab environment and/or in an operator network environment. For example, the one or more emulation devices may perform the one or more, or all, functions while being fully or partially implemented and/or deployed as part of a wired and/or wireless communication network in order to test other devices within the communication network. The one or more emulation devices may perform the one or more, or all, functions while being temporarily implemented/deployed as part of a wired and/or wireless communication network. The emulation device may be directly coupled to another device for purposes of testing and/or may perform testing using over-the-air wireless communications.

[0080] The one or more emulation devices may perform the one or more, including all, functions while not being implemented/deployed as part of a wired and/or wireless communication network. For example, the emulation devices may be utilized in a testing scenario in a testing laboratory and/or a non-deployed (e.g., testing) wired and/or wireless communication network in order to implement testing of one or more components. The one or more emulation devices may be test equipment. Direct RF coupling and/or wireless communications via RF circuitry (e.g., which may include one or more antennas) may be used by the emulation devices to transmit and/or receive data.

[0081] Disclosed herein are systems, methods, and instrumentalities for RIS (Reflective Intelligent Surface/Reconfigurable Intelligent Surface) discovery. A wireless transmit and receive unit (WTRU) may receive and decode RIS deployment information as part of a RIS discovery process. The WTRU may request to initialize a RIS discovery process and may request RIS service based on the discovered RISs. The WTRU may receive one or more messages in response to the RIS discovery request for the RIS selection process. The one or more messages may comprise signaling information, resource allocation information, performance requirement information, etc. The RIS discovery message may be based on downlink sounding or uplink sounding. The WTRU may perform a RIS selection process based on measurements, available RIS information, and/or channel conditions, and may send indications or reports which may include measurements, sets of selected RISs, preferred RIS states/configuration, a preferred RIS mode of operation, etc.

[0082] A WTRU may receive and decode RIS-related information, e.g., basic RIS-related information, in the downlink. The WTRU may request to initiate RIS discovery in the uplink. The WTRU may receive a response in the downlink to the RIS discovery request. If the response comprises a positive acknowledgement (ACK), the WTRU may request RIS service using an uplink transmission. The WTRU may receive RIS related scheduling information and may perform RIS based transmission or reception.

[0083] The disclosed systems, methods, and instrumentalities may be configured to perform topological node discovery, service request, selection, and configuration.

[0084] A goal, e.g., a primary goal, for 5G and beyond-cell ular systems may be to fulfill user experience requirements for throughput and reliability while maintaining energy efficiency across locations. Cellular systems may rely on fixed macro base stations deployments for providing coverage and services. This approach may not provide sufficient coverage in densely populated urban areas or at higher frequencies. Network densification may address this issue, but building new BS infrastructure from scratch may be timeconsuming and challenging due to various factors such as costs, power sourcing, real estate permissions, regulatory approvals, and/or backhaul availability. As a result, a number of topological solutions may be specified (e.g., in 3GPP) to deal with the above challenges, namely, IAB, NCR, and repeaters. Additionally, RIS may be considered as a topological solution for adoption in future cellular systems.

[0085] Integrated Access Backhaul (IAB) refers to decode and forwarding relays (e.g., L2 regenerative relays) which may provide a fast and cost-efficient alternative to fiber backhaul. Studies of architectures and radio protocols for IAB may be performed. A multi-hop NR-based IAB framework may have been specified where NR-Uu may be utilized for in-band and out-of-band backhauling. IAB evolution continues with additional features such as duplexing and efficiency enhancements. Work relating to IAB may be ongoing to explore further enhancements with vehicle mounted relays (VMR) (e.g., mobile BS relays mounted on vehicles).

[0086] The architecture of IAB may include lAB-donor and lAB-node. lAB-donor may be a central control node in the IAB network comprising lAB-donor-CU and lAB-donor-DU connected through a wired F1 interface. lAB-donor-DU may handle the lower protocol layers (e.g., PHY, MAC, and RLC) and lAB-donor- CU may handle the upper protocol layers (e.g., PDCP and SDAP/RRC). This functional split may permit time-sensitive functions to be handled by the lAB-donor-DU, which may be closer to the served nodes, and the remaining functions handled by the lAB-donor-CU, which may come with increased processing capacity. The lAB-node may be a relay node within the IAB network which may provide initial access to the parent node above it and access services to child nodes below it. lAB-node may comprise IAB-MT, linking IAB node with the DU of the parent node (e.g., either an lAB-donor or another lAB-node), and lAB-node- donor (or lAB-donor-DU) that serves the WTRUs and may serve downstream lAB-nodes in the example of multi-hop wireless backhauling. IAB-MT may use a standalone or shared IAB-DU antenna.

[0087] The topology of an IAB network may include lAB-donor serving as the central node where traffic may converge between the access and core networks. The IAB network may follow a tree-like structure with over-the-air links connecting multiple lAB-nodes. The lAB-donor-CU may establish connection with all lAB-donor-Dus using F1 interfaces (e.g., wired or wireless) and may be responsible for managing traffic to and from the core network and coordinating operations, e.g., all operations, within the IAB network. lAB- donor may provide wireless coverage to its child lAB-nodes. If a new lAB-node powers-up, it may be useful to, e.g., may need to, establish connection to the IAB network as a WTRU. This may be performed through acquiring an IP address and establishing a wireless F1 interface between the lAB-node-DU and the lAB- donor-CU. The configured lAB-node-DU may operate as a relay node within the IAB network. From the perspective of the WTRU, there may be no distinction between lAB-nodes, lAB-donors, and regular TRPs (transmission/reception point).

[0088] A challenge in deploying IAB may be potential interference across the wireless links. Resource allocation mechanisms may be used to mitigate interference. IAB specifications may employ TDM (timedivision multiplexing) with the parent node allocating available time resources to the child links of the IAB node, ensuring that the MT and DU sides may have non-overlapping receive and transmit states. This mechanism may eliminate self-interference between parent and child links. IAB enhancements may provide support for FDM (frequency-division multiplexing) and SDM (space-division multiplexing) to enable additional mechanisms for suppressing self-interference. Support for IAB operation in FD mode may improve spectrum efficiency and reduce latency.

[0089] Challenges for deploying mobile base station relays (MBSRs) such as VMRs may be addressed. These may include, for example, the following: MBSR switching IAB donor without causing disruption; location services for WTRUs accessing network through MBSRs; and efficient control for managing WTRU access to the 5G network using MBSRs. Further enhancements to the MBSR topology may be provided for multiple connectivity architectures, and for the extension of IAB application scenarios to domains such as NTN-based backhauling, urban air mobility, public safety, and disaster recovery scenarios.

[0090] IAB may provide a more efficient solution than deploying regular fully stacked cells. However, IAB may not always be an economically viable solution. There may also be challenges concerning interference between links and delay associated with the decoding operation (e.g., particularly in the example of multihop relaying).

[0091] Repeaters may be amplifying and forwarding (e.g., non-regenerative) relays which may provide a cost-effective solution relative to IAB. Repeaters may amplify and forward wireless signals in the RF domain and may be susceptible to noise and interference amplification. The use of higher frequencies in NR may pose additional constraints on the implementation of repeaters. For some repeaters, RF and electromagnetic compatibility (EMC) requirements targeting both frequency range 1 (FR1) and frequency range 2 (FR2) may be defined.

[0092] To further improve performance in terms of spatial directivity, unwanted interference amplification, and simplifying network integration, network-controlled repeater (NCR) may be employed as a stationary in-band RF repeater which may receive side control information from the gNB such as, for example, beam information, ON-OFF information, and/or time-division duplexing (TDD) downlink (DL)- uplink (UL) configuration information. [0093] NCR may comprise two functional entities: NCR-MT which provides the communication including side-control-information between the gNB and NCR through a C-link using the NR Uu interface; and NCR- Fwd, which may amplify and forward DL/UL RF signals between the gNB and the WTRU. NCR-MT (NCR mobile termination) and NCR-Fwd (NCR forwarding) may operate in the same or different frequency bands with at least one carrier used by the NCR-MT to be within the frequency band forwarded by the NCR-Fwd. NCR-Fwd may be implemented using beamforming antennas and one transceiver chain, but the performance requirements for beamforming antennas may not be as high as those for TRPs (transmission/reception point) or lABs (integrated access and backhaul).

[0094] The various forms of side-control-information for NCR specifications may be summarized as follows in connection with beam information (e.g., backhaul link and C-link), timing information, on-off information, and DL-UP configuration information.

[0095] Beam information may be employed in connection with a backhaul link and/or C-link. In an NCR system, the backhaul link and C-link may utilize fixed or adaptive beamforming. In a baseline scenario where the NCR-MT and NCR-Fwd operate within the same frequency band, the C-link and backhaul link may experience similar large-scale channel characteristics. As a result, the same TCI (transmission configuration indicator) states used for the C-link may also be applied to the NCR-Fwd for beamforming in the backhaul link. If adaptive beams are employed for both the C-link and backhaul link, the determination and indication of the backhaul link beams may be accomplished through new signaling provided by the gNB. In the absence of indication via the new signaling, the backhaul link beam may be determined based on a predefined rule.

[0096] For NCR-Fwd, the access link beam may be indicated using a beam index, considering both dynamic and semi-static indications, including semi-persistent indications. The time domain resource associated with the access link beam may be explicitly determined based on the indicated time domain resources. Due to the multiuser scheduling nature, the gNB may frequently change the transmission beam of the repeater. This frequent beam switching may result in PDCCH overhead and extended beam-switch delays. As a result, a single beam indication may represent one or multiple beams.

[0097] For the DL/UL of the access link in NCR-Fwd, beam correspondence may be assumed. The DL and UL beams on the access side that correspond to each other may have the same Bl (beam index). The forwarding direction of an indicated beam, either DL or UL, may be determined based on its corresponding time domain resource and the DL/UL TDD configuration. A gNB may guide the NCR through beam control information to perform periodic beam sweeping. Note the gNB may not have knowledge of the NCR’s beam characteristics, while the WTRU may not differentiate between beams originating from the gNB or the NCR. Based solely on the received signals, the WTRU may report its preferred Bl. The gNB may indicate Bl as a reference for the NCR’s transmit beamforming and may designate as the quasi-colocation (QCL) RS for determining the transmit beam to the WTRU. Following the network indication, the NCR may utilize the transmit beam corresponding to RS (reference signal) for subsequent forwarding and starting from a specified application time.

[0098] Timing information, ON-OFF information, and/or DL-UL configuration information may be employed. The following assumptions may hold for NCR timing: (i) NCR-Fwd DL and UL receive timing may respectively align with the NCR-MT DL and UL receive timing; (ii) NCR-Fwd DL transmit timing may be delayed by an internal delay after the NCR-MT (or NCR-Fwd) DL receive timing; and (iii) NCR-Fwd UL receive timing may be advanced by an internal delay before the NCR-MT (or NCR-Fwd) UL transmit timing. [0099] With ON-OFF information, NCRs may be turned off if not needed, resulting in power savings, but may also help with interference mitigation for high SINR users while maintaining performance for low SINR users. ON-OFF information may be recommended for NCRs to control the behavior of NCR-Fwd, providing benefits for network performance. The NCR-Fwd may be assumed, e.g., may be assumed by default, to be OFF unless explicitly or implicitly indicated by the gNB.

[0100] Regarding TDD DL/UL configuration, a semi-static TDD DL/UL configuration may be supported for the C-link, backhaul link, and/or access link. The NCR-Fwd default behavior may be set to OFF, based on the flexible symbol in the semi-static configuration. The same TDD UL/DL configuration may be assumed to be used for both the backhaul link and access link.

[0101] Further enhancements in the side control information for NCR may be provided. For example, power control may be employed to boost NCR performance. Strategies such as improvements in beam control and scheduling and utilizing diverse frequencies for the backhaul link may also be provided.

[0102] RIS may be a topological solution corresponding to a planar surface comprising a large number of scattering elements called unit-cells, whose response in the EM domain may be tuned to the propagation environment through control signaling. FIG. 2 depicts an example RIS. The RIS may be modeled as the combination of at least a RIS controller and a RIS panel as depicted in FIG. 2. The RIS panel may comprise a group of elements which may have the capability to change at least one of the properties of the incident radio waves including frequency, amplitude, phase, and polarization. The radio wave may be at least reflected or transmitted to another direction after hitting the RIS panel, depending on the design of RIS. The RIS micro-controller may refer to a component of RIS that may be responsible for configuring the RIS elements to achieve an intended manner of manipulation of the incident radio wave and potentially processing signaling received from another network node. The configuration of a RIS element by the micro- controller may be conveyed through control signaling from the RIS controller. Inside a RIS, one interface may be the interface between the RIS micro-controller and the RIS panel to transmit the control signals. [0103] RIS may turn a channel from a passive actor into a controllable entity through tuning of wireless signal reflections, refractions, focusing, collimation, modulation, and any combination of these. The associated characteristics of RIS may motivate a host of use examples including improving various system’s KPIs (key performance indicator), such as, for example, coverage and capacity, as well as enabling new applications such as, for example, localization and sensing. RIS may be implemented using mostly passive components (e.g., electronics such as pin diodes, varactor didoes, crystal liquids, etc.) without requiring any RF operation or signal processing. RIS as a topological solution may provide a number of characteristics in terms of cost, complexity, deployment flexibility, and energy-efficiency compared to network nodes such as full-stacked cells, lABs, NCRs, and repeaters.

[0104] The use of RISs to boost signal coverage and performance may be of interest as a result of their ability to tailor the RF characteristics of the reflected signals. A RIS may be a device comprising a large number of unit cells that may manipulate (e.g., reflect, refract, and/or absorb) electromagnetic waves impinging on it. A RIS may be used in wireless systems to partially control the properties of radio environments. Since RISs may comprise, e.g., typically comprise, a large number of antenna elements, they may be used to form very narrow beams which may lead to reinforced coverage. In examples, the unit cells may apply elementary phase shifts to the arriving wave as commanded by a RIS control unit. If a plane wave impinges on the RIS with a given angle of arrival (AoA), the angle of departure (AoD) of the reflected wave may depend on the AoA and the relative phases applied on the unit cells, which altogether may constitute a RIS beamforming vector. By adjusting those phases, the reflected wave may be steered to the desired direction and thereby improve coverage and/or capacity performance for the WTRU being serviced in UL and DL. Dynamically configuring RIS responses may be challenging, requiring devising a diverse set of RIS controlling strategies including gNB-controlled (e.g., through one or more gNBs) and WTRU-controlled (e.g., one or more WTRUs) as depicted, for example, in FIG. 3. FIG. 3 depicts an example RIS architecture wherein instructions for RIS state may be received at the RIS controller from a TRP or WTRU using control signaling.

[0105] Both a transmit antenna and a RIS unit-cell may be regarded as a collection of point sources that may emit polarized spherical waves. The reactive near-field zone of the antenna may vanish close to it and may be neglected. The radiative near-field (NF) and far-field zones may follow and be separated by the Rayleigh distance, dp= 2D²l , (where D is the maximum length of the antenna and A is the wavelength). The phase difference between a wave impinging at the center and the corner of an aperture may be, e.g., at most, rr/8. [0106] In the far-field, a wave may have an amplitude that may be constant over the receive antenna and may have a phase that may depend, e.g., may only depend, on the incident angle. In the radiative, NF (near field) amplitude variations at the Rx antenna may be neglected, but the phase variations may not be neglected. As the phases may not be coherent, e.g., may not be perfectly coherent, at the direction of maximum radiation, a reduction in the antenna gain may occur and an increase may occur in the main lobe’s beamwidth. Beams in the NF may be focused, e.g., may only be focused, on a spatial region which may be referred to as, for example, Depth of Field (DoF), or Depth of Focus, around the focal point. The focal point may be finite below C/F and may motivate the appearance of beam de-focusing effects and a corresponding SNR loss. Beams in the far field (e.g., beyond dp) may be focused, e.g., always be focused, and their DoF may extend to infinity. Although NF effects may be present in any scenario, the radiative NF region may be larger in RIS-based scenarios than in traditional scenarios because of the additional scattering from RIS (e.g., tunable reflections from the unit-cells), which may impair the ability to focus the energy in a given direction.

[0107] Deploying multiple topological nodes such as lABs, NCRs, repeaters, RISs or/and RISs with subsurfaces in the environment may provide opportunities for enhanced coverage and reliability including, for example, improved QoS, resource fairness, mobility, spectrum availability, energy efficiency, interference, etc. FIG. 4 depicts an example multi-RIS deployment. RISs may be seen as extension of a gNB or WTRU antennas by enhancing the reflection paths or clusters that may bring additional diversities to the channel for improved robustness and may increase the transmission layers for improved, e.g., higher, capacity. Synchronization over-the-air with multiple RISs may be supported as compared to other types of cooperative transmission with TRPs, RRHs (remote radio head), or repeaters.

[0108] Evolving/future RAN architectures may be expected to transition towards a more WTRU-centric architecture. This may be motivated by the increasing number of devices which introduces complexities for network deployment and operation. Accordingly, methods, procedures, and frameworks for WTRU controlling of topological nodes may be required to enable WTRU-centric networking.

[0109] RIS may be considered a potential topological solution alongside lABs, NCRs, and repeaters for shaping a smarter electromagnetic landscape in evolving/future RAN architectures. WTRU methods and procedures may be explained in the context of RIS-based deployment. The solutions disclosed herein may also be applicable to other topological nodes such as, for example, TRPs, lABs, relays, NCRs, repeaters, etc.

[0110] Each unit of RIS may be considered as a panel that may be built by close placement of many unit-cells where the functionality or state (e.g., reflection, refraction, absorption, etc.) of each unit-cell or a subset of unit-cells, e.g., RIS sub-surface, may be adjusted to result in a favorable reception at the receiver. A unit of RIS may be defined as a single installation of a RIS in a deployment. In a RIS-based deployment, more than one unit of RIS may exist, where each unit or a sub-surface of a RIS may be configured according to the transmission requirements of one or more WTRUs. The terms sub-surface of RIS, RIS, or unit of RIS may be used interchangeably. A RIS state may represent its overall reflection behavior that may include, for example, at least the overall phase shift(s) and/or amplification gain(s) associated with one or more unit-cell(s) or sub-surface(s) of RIS, e.g., all unit-cells of a RIS or all subsurfaces of a RIS.

[0111] In a RIS deployment, a WTRU may discover, e.g., first need to discover, the available unit of RIS and/or sub-surface, RIS discovery request, and may discover, e.g., secondly discover, whether any of available units and/or subsurface may be selected to aid communications, positioning, or sensing, e.g., RIS service request or RIS selection request. With multiple units of RIS, a set of RIS sub-surfaces from a single or multiple units of a RIS and/or a set of RISs (as depicted, for example, in FIG. 5), methods and procedures may be provided for a WTRU to discover, request RIS service, and control RIS towards RIS- aided transmission and reception.

[0112] In examples, a WTRU may receive and decode the RIS deployment information as part of the RIS discovery process. The WTRU may request to initialize a RIS discovery process and may request RIS service based on the discovered RISs. The WTRU may receive a message in response to the RIS discovery request for the RIS selection process including, for example, signaling information, resource allocation information, performance requirement information, etc. The indicated RIS discovery message may be based on downlink sounding or uplink sounding. The WTRU may perform RIS selection processes based on measurements, available RIS information, channel conditions, and send indications or reports which may include, for example, measurements, set of selected RISs, preferred RIS states/configuration, preferred RIS mode of operation, etc.

[0113] In examples, a WTRU may receive and decode information as a part of a RIS discovery process. A WTRU may receive information related to RIS deployment from the broadcast channel in the MIB or via a PDSCH transmission, e.g., SIB, WTRU-specific RRC (radio resource control) signaling, etc.

[0114] The information received by the WTRU may include the total number of deployed RISs, e.g., in a cell or a set of cells, the number of the activated RIS, RIS type (e.g., passive, semi-active, active), RIS mode (e.g., reflection, refraction, absorption, etc.), RIS phase resolution, RIS codebooks, RIS orientation, geo-location of available RIS within a cell, operating frequency, sub-surface grouping (e.g., fixed, dynamic), RIS area with increased NF effects, etc. [0115] The information may be transmitted via the broadcast channel in the MIB, or via a PDSCH transmission, e.g., SIB, etc. The information of different RISs may be split and indicated over multiple information blocks. In an example relating to 4 RISs, one RRC configuration may contain information regarding 2 RISs and a remaining 2 RISs’ information may be transmitted via another RRC configuration. In an example, the information regarding RIS types, RIS modes, etc., for each RIS may be indicated in individual SIBs, MIBs, etc.

[0116] The information may be transmitted, e.g., may always be transmitted, or may be transmitted in response to a request from a WTRU about availability and possibility of RIS serving the WTRU, e.g., RIS service request.

[0117] The information may be stored at the WTRU for future RIS service request. For example, the WTRU may utilize the information of the available RISs from the previously discovered RIS, e.g., stored in a database (e.g., geolocations, RIS IDs, etc.), to request RIS service.

[0118] Based on the received information, a WTRU may send a request to initiate RIS discovery processes. A request message may be carried in an uplink transmission, e.g., PUSCH, PUCCH, SRS, PRACH, etc., in, for example, a UCI, or a MAC CE information element.

[0119] The transmission carrying the message may be based on a dedicated pre-defined set of resources such as, for example, a specific subset of PUCCH or SRS (sounding reference signal) resources or resource sets.

[0120] The message may contain an indication of traffic type, expected reliability, buffer size, etc. The message may also indicate its primary usage. For example, the message may indicate whether the request may be intended, e.g., primarily intended, for enhancing its uplink performance or downlink performance.

[0121] The message may include an explicit index or identifier corresponding to the RIS units used for prior transmissions in the cell.

[0122] The message may contain some information related to the geo-location of the WTRU.

[0123] The message may contain a request for additional NF information, or for transmission of RS resources to measure NF effects by the TRP or the WTRU.

[0124] The request message may be periodic, semi-persistent, or aperiodic.

[0125] In response to the RIS discovery request, a WTRU may receive a message, e.g., via a PDCCH, PDSCH, etc., that may include one or more of an acknowledgement of availability of RIS to assist the WTRU and/or an implicit or explicit RIS identifier for the available RISs. The acknowledgement of availability of RIS to assist the WTRU may be included because a RIS may be already configured for another group of WTRUs, and re-adjustment of its RIS state may not be possible. [0126] If the WTRU receives positive acknowledgement on availability of RISs, it may receive additional information about the RIS discovery process, where the RIS discovery process may include one or more of the following: Type of the RIS discovery process, e.g., RIS selection based on a downlink sounding, e.g., by reception of a CSI-RS, or a RIS selection based on an uplink sounding, e.g., by an SRS, or RIS selection based on available RIS information e.g., geo-location, orientation, etc.; time resource (e.g., symbol, slot, frame, etc.), frequency resource (e.g., sub-carrier, resource block, bandwidth part, frequency, etc.), ports information, hopping pattern, repetition factor; spatial filter information, e.g., TCI information for CSI-RS reception, or spatial relation information for SRS transmission; time transmission properties, e.g., periodic, aperiodic, semi-persistent, configurable pattern, etc.; an implicit or explicit identifier for each transmission opportunity where the identifier may be a new index or based on an existing resource identifier, e.g., CRI (CSI reference signal resource indicator), SRI (sounding reference signal source indicator), PRI, etc.; the number of actively available RIS units for the discovery process; NF information related to the RIS, including for example, scheduling information about a transmitted or received RS for NF measurements, if requested by the WTRU; and/or indication that the RIS discovery process may be configured by RRC, MAC-CE, or DCI.

[0127] If the indicated RIS-discovery process is based on a downlink sounding, the WTRU may receive a downlink reference signal, e.g., a CSI-RS, according to the received configuration. A WTRU may perform a measurement for each of the configured reception occasions. The WTRU may report one or more indices corresponding to measurements. The number of reported measurements may be fixed, e.g., two best, or may be based on a condition of meeting a threshold, e.g., all the measurements that meet a threshold. The measurement may be in form of an RSRP (reference signal received power), SINR (signal interference - noise ratio), relative delay to a reference (e.g., SSB), delay profile, Doppler shift, Doppler spread, a quantity related to NF effects (e.g., a correlation value or function), etc. Following the measurements, a WTRU may receive one or more identifiers as implicit indication of the identified RIS units for support of its reception, e.g., one or more CRIs. In a solution, a WTRU may also receive an explicit RIS identifier. To assist a gNB, the explicit identifier may be reported as part of its future RIS discovery requests.

[0128] If the indicated RIS-discovery process is based on an uplink sounding, a WTRU may transmit an uplink reference signal, e.g., SRS, according to the received configuration. Following the transmissions, a WTRU may receive one or more identifier as an implicit indication of the identified RIS units for support of its transmission, e.g., one or more SRIs. A WTRU may also receive an explicit RIS identifier. To assist a gNB, the explicit identifier may be reported as part of its future RIS discovery requests.

[0129] If the WTRU receives positive acknowledgement on availability of RISs, or after receiving the indicated RIS-discovery process (e.g., using downlink or uplink sounding), the WTRU may request for RIS service including selection and configuration of one or group of RISs. The request message may be explicit in form of an uplink transmission, e.g., PUSCH, PUCCH, SRS, PRACH, etc., or may be implicit in form of certain selection of uplink resources, e.g., specific PUCCH resource, RACH resource, SRS resource, spatialrelationlnfo, etc.

[0130] The WTRU message may contain information such as RIS IDs, beam indices, etc., related to one, subset, or set of RISs from the discovered RISs for selection. The WTRU selection may be based on WTRU geolocation and information of available RISs, e.g., nearest 2 RISs, etc.

[0131] The message may indicate one or a set of preferred configurations or states of the discovered RISs requested for service which may include one or more of the following: phase/amplitude response; codebook; operating mode (reflection, refraction, absorption, etc.); MIMO scheme (e.g., spatial- multiplexing, diversity, etc.); unit-cell grouping; beam indication; etc.

[0132] The message may include information related to RIS resource requirements or expected RIS resources related to current or future transmissions, such as number of slots, symbol number, PRBs, ports, starting/end time units, etc.

[0133] As used herein, the terms ‘a’ and ‘an’ and similar phrases may be interpreted as ‘one or more’ and ‘at least one’. A term which ends with the suffix ‘(s)’ may be interpreted as ‘one or more’ and ‘at least one’. The term ‘may’ may be interpreted as ‘may, for example’. A sign, symbol, or mark of forward slash ‘I’ may be interpreted as ‘and/or’ unless particularly mentioned otherwise, where for example, ‘A/B’ may imply ‘A and/or B’.

[0134] A WTRU may transmit or receive a physical channel or reference signal according to at least one spatial domain filter. The term “beam” may be used to refer to a spatial domain filter.

[0135] The WTRU may transmit a physical channel or signal using the same spatial domain filter as the spatial domain filter used for receiving an RS, such as CSI-RS or a SS (synchronization signal) block. The WTRU transmission may be referred to as “target,” and the received RS or SS block may be referred to as “reference” or “source.” In an example, the WTRU may transmit the target physical channel or signal according to a spatial relation with a reference to such RS or SS block.

[0136] The WTRU may transmit a first physical channel or signal according to the same spatial domain filter as the spatial domain filter used for transmitting a second physical channel or signal. The first and second transmissions may be referred to as “target” and “reference” (or “source”), respectively. In an example, the WTRU may transmit the first (target) physical channel or signal according to a spatial relation with a reference to the second (e.g., reference) physical channel or signal. [0137] A spatial relation may be Implicit, configured by RRC, or signaled by MAC CE or DCI. For example, a WTRU may implicitly transmit PUSCH and DM-RS of PUSCH according to the same spatial domain filter as an SRS (sounding reference signal) indicated by an SRI indicated in DCI or configured by RRC. In an example, a spatial relation may be configured by RRC for an SRI or signaled by MAC CE for a PUCCH. Such spatial relation may also be referred to as a “beam indication”.

[0138] The WTRU may receive a first (e.g., target) downlink channel or signal according to the same spatial domain filter or spatial reception parameter as a second (e.g., reference) downlink channel or signal. For example, such association may exist between a physical channel such as PDCCH or PDSCH and its respective DM-RS. At least if the first and second signals are reference signals, such association may exist if the WTRU may be configured with a QCL assumption type D between corresponding antenna ports. Such association may be configured as a TCI state. A WTRU may be indicated an association between a CSI-RS or SS block and a DM-RS by an index to a set of TCI states configured by RRC and/or signaled by MAC CE. Such indication may also be referred to as a “beam indication”.

[0139] A unified TCI, e.g., a common TCI, a common beam, a common RS, etc., may refer to a beam/RS to be simultaneously used for multiple physical channels/signals. The term “TCI” may at least comprise a TCI state that includes at least one source RS to provide a reference (e.g., WTRU assumption) for determining QCL and/or spatial filter.

[0140] In an example, a WTRU may receive from a gNB an indication of a first unified TCI to be used/applied for both a PDCCH and a PDSCH and a downlink RS. The source reference signal(s) in the first unified TCI may provide common QCL information at least for WTRU-dedicated reception on the PDSCH and all (or subset of) CORESETs in a CC. In an example, a WTRU may receive from a gNB an indication of a second unified TCI to be used/applied for both an PUCCH and an PUSCH, and an uplink RS. The source reference signal(s) in the second unified TCI may provide a reference for determining common UL TX spatial filter(s) at least for dynamic-grant/configured-grant based PUSCH and all (or subset of) dedicated PUCCH resources in a CC.

[0141] The WTRU may be configured with a first mode for unified TCI (e.g., SeparateDLULTCI mode) where an indicated unified TCI (e.g., the first unified TCI or the second unified TCI) may be applicable for either downlink (e.g., based on the first unified TCI) or uplink (e.g., based on the second unified TCI). In an example, a WTRU may receive (e.g., from a gNB) an indication of a second unified TCI to be used/applied commonly for a PDCCH, a PDSCH, a PUCCH, and a PUSCH (and a DL RS and/or a UL RS). The WTRU may be configured with a second mode for unified TCI (e.g., JointTCI mode) where an indicated unified TCI, e.g., the third unified TCI, may be applicable for both downlink and uplink. [0142] The WTRU may determine a TCI state applicable to a transmission or reception by first determining a Unified TCI state instance applicable to this transmission or reception, and then determining a TCI state corresponding to the Unified TCI state instance. A transmission may consist of at least PUCCH, PUSCH, SRS. A reception may consist of at least PDCCH, PDSCH, CSI-RS. A Unified TCI state instance may also be referred to as TCI state group, TCI state process, unified TCI pool, a group of TCI states, a set of time-domain instances/stamps/slots/symbols, and/or a set of frequency-domain instances/RBs/subbands, etc. A Unified TCI state instance may be equivalent or identified to a Coreset Pool identity (e.g., CORESETPoollndex, a TRP indicator, and/or the like).

[0143] Unified TCI may be interchangeably used with one or more of unified TCI-states, unified TCI instance, TCI, and TCI-state while being consistent with the systems, methods, and instrumentalities described herein.

[0144] A TRP, e.g., transmission and reception point, may be interchangeably used with one or more of TP (transmission point), RP (reception point), RRH (radio remote head), DA (distributed antenna), BS (base station), a sector (of a BS), and a cell (e.g., a geographical cell area served by a BS), while being consistent with the systems, methods, and instrumentalities described herein. Hereafter, Multi-TRP may be interchangeably used with one or more of MTRP, M-TRP, and multiple TRPs, while being consistent with the systems, methods, and instrumentalities described herein.

[0145] A WTRU may be configured with (or may receive configuration of) one or more TRPs to which the WTRU may transmit and/or from which the WTRU may receive. The WTRU may be configured with one or more TRPs for one or more cells. A cell may be a serving cell, special cell, secondary cell, nonserving cell, etc.

[0146] A WTRU may be configured with at least one RS for the purpose of channel measurement. This RS may be denoted as a Channel Measurement Resource (CMR) and may comprise a CSI-RS, SSB, or other downlink RS transmitted from the TRP to a WTRU. A CMR may be configured or associated with a TCI state. A WTRU may be configured with a CMR group where CMRs transmitted from the same TRP may be configured. Each group may be identified by a CMR group index (e.g., group 1). A WTRU may be configured with one CMR group per TRP, and the WTRU may receive a linkage between one CMR group index and another CMR group index, or between one RS index from one CMR group and another RS index from another group.

[0147] A WTRU may be configured with (or receive configuration of) one or more pathloss (PL) reference groups (e.g., sets) and/or one or more SRS groups, SRS resource indicator (SRI) or SRS resource sets. [0148] A PL reference group may correspond to or may be associated with a TRP. A PL reference group may include, identify, correspond to, or be associated with one or more TCI states, SRIs, reference signal sets (e.g., CSI-RS set, SRI sets), CORESET index, and or reference signals (e.g., CSI-RS, SSB).

[0149] A WTRU may receive a configuration (e.g., any configuration described herein). The configuration may be received from a gNB or TRP. For example, the WTRU may receive configuration of one or more TRPs, one or more PL reference groups, and/or one or more SRI sets. A WTRU may implicitly determine an association between a RS set/group and a TRP. For example, if the WTRU is configured with two SRS resource sets, the WTRU may determine to transmit to TRP1 with SRS in the first resource set, and to TRP2 with SRS in the second resource set. The configuration may be via RRC signaling.

[0150] In the example, TRP, PL reference group, SRI group, and SRI set may be used interchangeably. The terms “set” and “group” may be used interchangeably herein.

[0151] A WTRU may report a subset of channel state information (CSI) components, where CSI components may correspond to at least a CSI-RS resource indicator (CRI), a SSB resource indicator (SSBRI), an indication of a panel used for reception at the WTRU (such as a panel identity or group identity), measurements such as L1 -RSRP, L1-SINR taken from SSB or CSI-RS (e.g., cri-RSRP, cri-SINR, ssb-lndex-RSRP, ssb-lndex-SINR), and other channel state information such as at least rank indicator (Rl), channel quality indicator (CQI), precoding matrix indicator (PMI), Layer Index (LI), and/or the like.

[0152] In examples, a property of a grant or assignment may comprise one or more of the following: a frequency allocation; an aspect of time allocation, such as a duration; a priority; a modulation and coding scheme; a transport block size; a number of spatial layers; a number of transport blocks; a TCI state, CRI, or SRI; a number of repetitions; whether the repetition scheme is Type A or Type B; whether the grant is a configured grant type 1, type 2, or a dynamic grant; whether the assignment is a dynamic assignment or a semi-persistent scheduling (configured) assignment; a configured grant index or a semi-persistent assignment index; a periodicity of a configured grant or assignment; a channel access priority class (CAPC); and/or any parameter provided in a DCI, by MAC, or by RRC for the scheduling the grant or assignment.

[0153] In examples, an indication by DCI may comprise one or more of the following: an explicit indication by a DCI field or by RNTI used to mask CRC of the PDCCH; and/or an implicit indication by a property such as DCI format, DCI size, Coreset or search space, Aggregation Level, first resource element of the received DCI (e.g., index of first Control Channel Element), where the mapping between the property and the value may be signaled by RRC or MAC [0154] In examples, a signal may be interchangeably used with one or more of following consistent with systems, methods, and instrumentalities described herein: sounding reference signal (SRS); channel state information - reference signal (CSI-RS); demodulation reference signal (DM-RS); phase tracking reference signal (PT-RS); and/or synchronization signal block (SSB)

[0155] A channel may be interchangeably used with one or more of following consistent with systems, methods, and instrumentalities described herein: physical downlink control channel (PDCCH); physical downlink shared channel (PDSCH); physical uplink control channel (PUCCH); physical uplink shared channel (PUSCH); physical random access channel (PRACH).

[0156] Downlink reception may be used interchangeably with Rx occasion, PDCCH, PDSCH, SSB reception, consistent with systems, methods, and instrumentalities described herein.

[0157] Uplink transmission may be used interchangeably with Tx occasion, PUCCH, PUSCH, PRACH, SRS transmission, consistent with systems, methods, and instrumentalities described herein.

[0158] RS may be interchangeably used with one or more of RS resource, RS resource set, RS port and RS port group, consistent with systems, methods, and instrumentalities described herein.

[0159] RS may be interchangeably used with one or more of SSB, CSI-RS, SRS, and DM-RS, consistent with systems, methods, and instrumentalities described herein.

[0160] In examples, time instance may be interchangeably used with slot, symbol, subframe, consistent with systems, methods, and instrumentalities described herein.

[0161] In examples, the terms RS and pilot may be used interchangeably. In an OFDM system, an RS/pilot may comprise multiple (e.g., multiple known) reference/pilot symbols mapped to different subcarriers and OFDM symbols.

[0162] A RIS state may represent its overall reflection behavior that may include at least the overall phase shift(s) and/or amplification gain(s) associated with one or more unit-cell(s) or sub-surface(s) of RIS, e.g., all unit-cells of a RIS or all sub-surfaces of a RIS.

[0163] A RIS state may correspond to an M-tuple of RIS element factors, e.g., a set of values of all RIS element factors of a RIS.

[0164] A RIS state may also correspond to an S-tuple of RIS sub-surface factors, e.g., a set of values of all S sub-surfaces factors of a RIS.

[0165] A RIS state with S RIS sub-surface factors may be mapped to a RIS state with M RIS element factors by setting the RIS element factors that belong to a sub-surface to the corresponding sub-surface factor. [0166] The terms RIS state and RIS configuration may be used interchangeably herein.

[0167] The Rayleigh distance may be the distance above which the phase difference between a wave impinging at the center and the corner of a receive aperture is at most TT/8. The terms “Rayleigh distance” and “Fraunhofer distance” may be interchangeable used herein.

[0168] Rayleigh distance may be used to delimit the beginning of the far-field region, but the real impact of NF effects may depend on the geometry and may be quantified, e.g., may only be quantified, by evaluating the receiver’s location in relation to the depth of focus of the beams in use.

[0169] A cellular scenario may be considered with TRPs, WTRUs, and topological nodes deployed in the environment. Each TRP, or a group of TRPs, may serve one or several WTRUs without using the RIS nodes (e.g., legacy system), or utilize one or several RISs (e.g., RIS-based system).

[0170] FIG. 5 depicts an example RIS-aided system. Considering a single TRP-RIS-WTRU as an exemplary scenario (illustrated in FIG. 5), the equivalent baseband received complex-valued scalar signal y_m at the WTRU may be given by Equation 1.

Equation

[0171] wherein: x may be the complex-valued scalar symbol, e.g., a known reference (pilot) symbol; P may be the complex-valued precoding vector of dimension N_T x 1, where N_T is the number of transmit antennas or antenna ports, e.g., at a network-side TRP; d' = [do ••• dw_T-i] may be the complexvalued channel between the TRP and the WTRU, excluding propagation paths via the RIS, of dimension 1 x N_T, a_m' is the complex-valued vector channel between the TRP and the RIS element, of dimension 1 x N_T, c_m' = b_ma_m' may be the cascaded complex-valued vector channel between the TRP, RIS element m, and the WTRU, of dimension 1 x W_T; b_m is the complex-valued scalar channel between the RIS element and the WTRU; z is the additive noise and interference; and (p_m = a_me^jl3m may be the complex-valued scalar RIS element factor of RIS element m, with m=1, ..., M;. In a passive RIS, the factor may have a fixed amplitude, e.g., a unit amplitude (| _m | = a_m = 1). In an active or hybrid RIS, the amplitude a_m may be variable and controllable. The maximum amplification may be limited, e.g., a_m < “max for all m. In some examples, e.g., even for a passive RIS, a RIS element may be turned off, i.e. , (p_m = 0 or (p_m « 0. A RIS element may be in a certain state ( _m) at a time and is assumed to be applicable to all sub-carriers within a certain bandwidth.

[0172] The model may be further simplified by including the TRP precoding P into the TRP-to-RIS channel.

Equation 2: y_m = (,b_ma_m(p_m + d)x + z = (c_m(p_m + d)x + z [0173] wherein: d = d'P may be the complex valued scalar effective direct TRP-to-RIS channel (including TRP precoding); a_m = a_m' P may be the complex-valued scalar channel between the TRP and the RIS element; and c_m = b_ma_m may be the cascaded complex-valued scalar channel TRP to m:th RIS element to WTRU.

[0174] An exemplary model including all RIS elements may be obtained by adding the signals corresponding to all M RIS elements of the RIS (c_m(p_ms).

Equation 3: y = ((a© )<t> + d)x + z = (c<I> + d)x + z

[0175] wherein: a may be the complex-valued vector channel between the TRP and the RIS, of dimension 1 x M, where M is the number of RIS elements; b may be the complex-valued vector channel between the RIS and the WTRU (e.g., UE), also 1 x M; c = aQb = bQa may be the element-wise (Hadamard) product of a and b, <I> may be the complex-valued vector of dimension M x 1 containing the M RIS element factors (p_m. <I> may correspond to the RIS state. A RIS state may correspond to an M- tuple of RIS element factors, e.g., a set of values of all RIS element factors of a RIS. A RIS state may also correspond to an S-tuple of RIS sub-surface factors, e.g., a set of values of all S sub-surfaces factors of a RIS. A RIS state with S RIS sub-surface factors may be mapped to a RIS state with M RIS element factors by setting the RIS element factors that belong to a sub-surface to the corresponding sub-surface factor. The term RIS configuration may be used to denote a RIS state. The terms RIS state and RIS configuration may be used interchangeably herein.

[0176] In examples, a rectangular RIS, Mh may denote the number of RIS elements in a first direction, e.g., horizontal, and M_v may denote the number of RIS elements in a second direction, e.g., vertical, such that M=Mh*M_v.

[0177] To benefit from deploying topological nodes such as, for example, IAB, NCR, repeater, RIS, etc., there may be, may need to be, mechanisms for WTRUs to discover and request services. By discovering RISs, the WTRUs may assist the gNB for selection or grouping of the RIS nodes, provide beam-based measurements or feedback codebooks for the RIS-aided links, and to enable WTRU-assisted or WTRU- controlled RIS. The latter may be particularly relevant to deploying RIS units in indoor environments. The multiple RISs may be used for a variety of applications including, for example, the following: communications-based enhancements which may comprise, for example, improving spatial-multiplexing MIMO capabilities and hence spectral efficiency by improving channel rank in FR1 , and establishing LoS communications for higher-frequencies such as FR2 and sub-THz/THz; positioning, localization and sensing which may comprise, for example, improving positioning accuracy in indoor scenarios by having multiple RISs, allowing for sensing of target objects in an environment, etc. [0178] RIS discovery and service request procedures may result in various performance improvements depending on the system and use example under consideration. Some examples include the following: WTRU procedures/signaling based on RIS discovery to enable channel access to RIS (both for licensed and unlicensed bands); RIS configuration including codebook, beams, pattern for deployments in indoor, outdoor, and O2I; selection/grouping of multiple RISs for aiding M-TRP transmission; beam-based, ON/OFF, etc., and/or interference mitigation with multiple RISs deployed; per-element group or sub- surface-based control of RIS by the WTRU.

[0179] A WTRU may determine the presence and availability of RIS for its transmission or reception based on measurements, available RIS information, and/or channel conditions. The WTRU may request for RIS service by sending indications or reports which may include, for example, measurements, a set of selected RISs, a preferred RIS states/configuration, a preferred RIS mode of operation etc. Based on the determined state of RIS, a WTRU may transmit or receive based on the received scheduling information. [0180] A WTRU may receive and decode basic RIS-related information as a part of a RIS discovery process. The WTRU may receive information related to RIS deployment from the broadcast channel in the MIB, or via a PDSCH transmission, e.g., SIB, WTRU-specific RRC signaling, etc.

[0181] The RIS-based information received by the WTRU may include one or more of the following: the number of available RISs or set of activated RISs, which may be identified by an index, e.g., using candidate RIS IDs, beam IDs, etc.; RIS modes of operation (e.g., reflection, refraction, transmissive, absorption, etc.), e.g., using one or more TCI states related to one or multiple RS resources (or beams) for each mode, or using one or multiple RS resources (or beams) for each mode; RIS types or categories (e.g., passive, semi-active, active), e.g., using one or more TCI states related to one or multiple RS resources (or beams) for each type/category; RIS configuration set (e.g., reflection angle or set of angles, amplification value or set of values, phase resolution, amplitude resolution, # of unit-cells, # of subsurfaces, etc.); at least one RIS activation/application time that may capture the required time for switching from one mode of RIS operation to another, e.g., form RIS-configuration-set1 to RIS-configuration-set2, or RIS-off to RIS-on, etc.; RIS availability information expressed by system parameters (e.g., slot index, radio frame index, SFN number, BWP-id), e.g., related to a serving cell or one or more of TRPs, for example configured through a RIS reference cell ID; orientation and geolocation (e.g., positioning) information; operating frequency, time location, bandwidth of influence, etc.; measurement RS information associated with RISs; beam related information, e.g., QCL information, TCI, spatialRelationlnfo, etc.; information about NF effects related to RISs, e.g., the coverage area around one or more RISs where NF effects are more significant (e.g., given as the Rayleigh distances, a geo-located area around the one or more RISs showing increased NF effects, etc.), the depth of focus of one or more TCI states (or beams), an SNR loss or beamwidth increase resulting from NF, etc.

[0182] The different RIS-based information such as RIS modes and configuration may be associated with an ID that may be communicated between the RIS, gNB, and WTRU. The indication may be dynamic (e.g., DCI) or using higher-layer configuration (e.g., MAC-CE/RRC).

[0183] The WTRU may receive and decode the RIS deployment information as part of the RIS discovery process. The WTRU may receive and decode the RIS-based information from one or more of: a gNB/TRP; a source WTRU; and/or a RIS controller.

[0184] The WTRU may receive the RIS-based information from a gNB/TRP. A WTRU may receives the RIS-based information from the broadcast channel in the MIB. The fields of the MIB carried by PBCH may be modified to incorporate RIS-based information, e.g., adding a new field RIS-positions. A WTRU may receive the RIS-based information via a PDSCH transmission, e.g., SIB, WTRU-specific RRC signaling, etc.

[0185] The WTRU may receive the RIS-based information from a source WTRU. The source WTRU may have originally received the RIS-based information from the RIS-controller, gNB/TRP, or another source WTRU. The source WTRU may send the RIS discovery information to the target WTRU. The communication may be through use of one or several RISs.

[0186] The WTRU may receive the RIS-based information from a RIS controller that may be equipped with a radio unit configured to send the RIS-based information for the discovery of RISs. A new set of physical channels may be specified for this purpose, e.g., broadcast or control channel for RIS controller. In examples, existing channels may be used for this purpose, e.g., PDCCH and/or PDSCH, e.g., using an RNTI, e.g., a new RNTI for RIS. In examples, sidelink channels may be used such as PSCCH and/or PSSCH.

[0187] In examples, the gNB/TRP may configure the RIS controller to broadcast the RIS-based information. The configuration may correspond to periodic, semi-periodic, or aperiodic transmission.

[0188] In examples, the gNB/TRP may provide the RIS controller with relevant side-control-information to assist with the broadcasting of the RIS-based information. The side control information may include one or more of the following: RIS-mode-information: indicated RIS mode of operation such as reflection, refraction, transmissive, absorption, transmitting, receiving, etc.; RIS-controlling-information: indication of the RIS controlling mechanism including gNB-controlled, gNB-assisted, WTRU-controlled, or autonomous; Spatial-information: explicit or implicit amplitude, phase or both, directivity, beamforming information; in one solution, spatial-information may be indicated as part of the TCI framework (e.g., for one or multiple beams); TDD-information: UL/DL resource information, e.g., dedicated slots for DL, UL, or flexible slots, for resource utilization and interference management purposes; Timing-information: applicability duration for a given RIS configuration, transmission alignment; and/or ON/OFF-information: for efficiency and interference management purposes, RIS, or one or group of unit-cells, or sub-surfaces of RIS may be turned off.

[0189] In examples, the RIS controller may send ACK/NACK or status report to indicate successful reception of the control information from gNB/TRP.

[0190] In examples, the communication between gNB/TRP and RIS controller (e.g., for carrying control signals) may be through the Uu interface. The control information may be carried in downlink over PDCCH or PDSCH, or uplink over PUCCH, PUSCH, etc.

[0191] The RIS-based information of multiple RISs may be split and indicated over multiple information blocks. For example, if 4 RISs are employed, one RRC configuration may contain information regarding 2 RISs and the remaining 2 RISs information may be transmitted via another RRC configuration. In an example, the information regarding RIS types, RIS modes, etc., for each RIS may be indicated in individual SIB(s), MIB(s), etc.

[0192] The information may be stored at the WTRU for a future RIS service request. For example, the WTRU may utilize the information of the available RISs from the previously discovered RIS, e.g., stored in a database (e.g., geolocations, RIS IDs, etc.), to request RIS service.

[0193] A RIS (e.g., RIS controller and/or RIS surface) may be associated with one or more RIS IDs of one or more types.

[0194] A first type of RIS ID may be used to distinguish a RIS across many cells, e.g., in a network, country, region, or globally. The first type of RIS ID may be associated with or based on a MAC address, or another ID that may be hard coded into the RIS by the RIS vendor. The RIS may report its RIS ID of the first type to the network upon RIS initial access. The network may use a RIS ID of the first type to configure or indicate a RIS ID to a WTRU as discussed herein.

[0195] A second type of RIS ID may be cell-specific or WTRU-specific and may be configurable. A RIS ID of the second type may be selected by the network, a WTRU, or the RIS controller. A cell specific RIS ID of the second type may be used for RIS-related configuration, indication, etc., in the corresponding cell. The RIS ID may be a part of the system information of the cell or serving cell RRC configuration. A RIS configured/indicated to a WTRU may have different RIS IDs of the second type in different cells. A WTRU- specific RIS ID of the second type may be used for RIS-related configuration, indication, etc., by the WTRU in one or more cells, e.g., serving cells. The RIS ID may be a part of the system information of a cell or a serving cell RRC configuration, but may be applied also to a set of cells, e.g., a set of cells in a configured list, a set of cells in a cell group, etc.

[0196] In examples, a WTRU may receive both a RIS ID of a first type and a RIS ID of a second type. The network may indicate that a RIS ID of a first type and a RIS ID of a second type correspond to the same RIS. Based on this information, the WTRU may determine that two different RIS IDs of the second type, e.g., in two different cells, correspond to the same RIS, e.g., the two different RIS IDs of the second type correspond to the same RIS ID of the first type.

[0197] RIS-based information may be transmitted, e.g., may always be transmitted, or may be transmitted in response to a request from a WTRU about availability and possibility of RIS serving the WTRU, e.g., RIS service request. The WTRU-based triggers for transmitting RIS-based information may be explicit indication from the WTRU (e.g., part of UCI) or implicitly based on certain received signal quality, beam quality, interference level, mobility condition, etc.

[0198] The information may be stored at the WTRU for a future RIS service request. For example, the WTRU may utilize the information of the available RISs from the previously discovered RIS, e.g., stored in a database (e.g., geolocations, RIS IDs, etc.), to request RIS service.

[0199] Based on the received information, a WTRU may send a request to initiate an RIS discovery processes.

[0200] The request message may be carried in an uplink transmission, e.g., PUSCH, PUCCH, SRS, PRACH, etc., for instance in a UCI, or a MAC-CE information element. In examples, the initial request may be made by a dedicated new service request signal.

[0201] In examples, a RIS discovery signal that may also initiate a service request may be based on one or more of the following: the transmission carrying the message may be based on a dedicated pre-defined set of resources which may be, for example, a specific subset of PUCCH or SRS resources or resource sets, such as, for example, an SR (scheduling request) associated with logical channel ID that may be associated with RIS discovery; the message may contain an indication of traffic type, expected reliability, buffer size, state of mobility, RS measurement metrics, such as RSRP, CQI, RS index, etc., and the message may also indicate its primary usage, e.g., whether the request is primarily intended for enhancing its uplink performance, downlink performance, or both; the message may include an explicit index or identifier corresponding to the RIS units used for prior transmissions in the cell; the message may contain some information related to the geo-location of the WTRU; the message may contain a request for additional NF information (e.g., if not previously received by the WTRU as part of the RIS-related information message), or for transmission of RS resources (e.g., a CSI-RS) to measure NF effects by the TRP or the WTRU (e.g., for beam correlation measurements); and/or the request message may be transmitted in a periodic, semi-persistent, or aperiodic manner.

[0202] In response to the RIS discovery request, a WTRU may receive a message, e.g., via a PDCCH, PDSCH, etc., that may include one or more of the following: an implicit or explicit RIS identifier for the available RISs; and/or an acknowledgement of availability of RIS to assist the WTRU in an example wherein a RIS may have previously been configured for another group of WTRU, and re-adjustment of its RIS state may not be possible.

[0203] If a WTRU receives positive acknowledgement on availability of RISs, it may receive additional information about the discovered RIS, where the information may include one or more of the following: Type or Types of the discovered RISs, e.g., RIS selection based on a downlink sounding, e.g., by reception of a CSI-RS, or a RIS selection based on an uplink sounding, e.g., by an SRS, or RIS selection based on available RIS information e.g., geo-location, orientation, etc.; time resource (e.g., symbol, slot, frame, etc.), frequency resource (e.g., sub-carrier, resource block, bandwidth part, frequency, etc.), ports information, hopping pattern, repetition factor wherein a WTRU may use these resources for RIS selection, e.g., system parameters may be used to predetermine or preconfigure RIS mode, type, etc.; spatial filter information, e.g., TCI information for CSI-RS reception, or spatial relation information for SRS transmission; time transmission properties, e.g., periodic, aperiodic, semi-persistent, configurable pattern, etc., for instance of a downlink or uplink physical signals/channels used for RIS discovery; an implicit or explicit identifier for each transmission opportunity wherein the identifier may be a new index or based on an existing resource identifier, e.g., CRI, SRI, PRI, etc.; the number, IDs, etc., of actively available RIS units resulted from the discovery process which also may include other information, for example, including additional details such as number of sub-surfaces, etc.; NF information related to the RIS, including, e.g., scheduling information about a transmitted or received RS for NF measurements, if requested by the WTRU; and/or RIS discovery process may be configured by RRC, MAC-CE, or DCI and MAC+-CE and/or DCI may be used to activate, deactivate, and/or switch between different configurations.

[0204] If the indicated RIS-discovery process may be based on a downlink sounding, a WTRU may receive a downlink reference signal, e.g., a CSI-RS, according to the received configuration. A WTRU may perform a measurement for each of configured reception occasions. A WTRU may report one or more indices that correspond to measurements. The number of reported measurements may be fixed, e.g., two best, or based on a condition of meeting a threshold, e.g., all the measurements that meet a threshold. The measurement may be in form of an RSRP, SINR, relative delay to a reference (e.g., SSB), delay profile, Doppler shift, Doppler spread, a quantity related to NF effects (e.g., a correlation value or function), etc. Following the measurements, a WTRU may receive one or more identifiers as implicit indication of the identified RIS units for support of its reception, e.g., one or more CRIs, TCI state(s), etc. In examples, a WTRU may also receive an explicit RIS identifier. To assist a gNB, the explicit identifier may be reported as part of its future RIS discovery requests.

[0205] If the indicated RIS-discovery process is based on an uplink sounding, a WTRU may transmit an uplink reference signal, e.g., SRS, according to the received configuration. Following the transmissions, a WTRU may receive one or more identifiers as an implicit indication of the identified RIS units for support of its transmission, e.g., one or more SRIs. In examples, a WTRU may also receive an explicit RIS identifier. To assist a gNB, the explicit identifier may be reported by the WTRU as part of its future RIS discovery requests.

[0206] If a WTRU receives positive acknowledgement on availability of RISs, or after receiving the indicated RIS-discovery process information (e.g., using downlink or uplink sounding), the WTRU may request for RIS service including selection and configuration of one or group of RISs. This may be an option for the WTRU to base the selection using information received from the gNB.

[0207] The request message may be explicit in form of an uplink transmission, e.g., PUSCH, PUCCH, SRS, PRACH, etc., or implicit in form of certain selection of uplink resources, e.g., specific PUCCH resource, RACH resource, SRS resource, spatialrelationlnfo, etc.

[0208] The WTRU message may contain information such as RIS IDs, beam indices, etc., related to one, a subset, or set of RISs from the discovered RISs for selection. The WTRU may determine the message information based on measurements, received information, etc.

[0209] The WTRU selection may be based on WTRU geolocation and information of available RISs, e.g., nearest 2 RISs, etc.

[0210] The message may indicate one or a set of preferred configurations or states of the discovered RISs requested for service which may include one or more of phase/amplitude response, codebook, operating mode (e.g., reflection, refraction, absorption, etc.), MIMO scheme (e.g., spatial-multiplexing, diversity, etc.), unit-cell grouping, beam indication, etc. In examples, the WTRU may perform the end selection, at a minimum requests RIS service, and the gNB may apply the selection or decide on its own for RIS-based service.

[0211] The message may include information related to RIS resource requirements or expected RIS resources related to current or future transmissions, such as number of slots, symbol number, PRBs, ports, starting/end time units, etc. [0212] An exemplary signaling flowchart capturing methods associated with RIS related information, RIS discovery, and RIS service is provided in FIG. 6. In FIG. 6, exemplary gNB to WTRU interaction is depicted.

[0213] Although features and elements described herein 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 other features and elements.

[0214] The description herein may be provided for exemplary purposes and does not limit in any way the applicability of the described systems, methods, and instrumentalities to other wireless technologies and/or to wireless technology using different principles, when applicable. The term network in this disclosure may refer to one or more gNBs which in turn may be associated with one or more Transmission/Reception Points (TRPs) or any other node in the radio access network.

[0215] Although the implementations described herein may consider 3GPP specific protocols, it is understood that the implementations described herein are not restricted to this scenario and may be applicable to other wireless systems. For example, although the solutions described herein consider LTE, LTE-A, New Radio (NR) or 5G specific protocols, it is understood that the solutions described herein are not restricted to this scenario and are applicable to other wireless systems as well.

[0216] The processes described herein 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 (transmitted over wired and/or wireless connections) and/or computer-readable storage media. Examples of computer- readable storage media include, but are not limited to, a read only memory (ROM), a random access memory (RAM), a register, cache memory, semiconductor memory devices, magnetic media such as, but not limited to, internal hard disks and removable disks, magneto-optical media, and/or optical media such as compact disc (CD)-ROM disks, and/or digital versatile disks (DVDs). A processor in association with software may be used to implement a radio frequency transceiver for use in a WTRU, terminal, base station, RNC, and/or any host computer.

Claims

CLAIMS What is Claimed:

1 . A wireless transmit and receive unit (WTRU), comprising: a processor configured to: receive information associated with available Reflective Intelligent Surfaces (RISs) available for communication with the WTRU; send, based on the received information, a request to initiate discovery of one or more of the available RISs; receive at least one response message, the at least one response message comprising an indication of a number of RISs, RIS identifiers, a number of sub surfaces, frequency resources, near field information, and a type of RIS discovery; and on a condition that the type of RIS discovery is associated with downlink, perform a measurement for a configured reception occasion; report an index associated with the measurement; and receive an identifier associated with a RIS; and send a request for service from at least one of the available RISs.

2. The WTRU of claim 1 , wherein the processor is further configured to: send a request regarding availability of RISs for communication with the WTRU, wherein the processor configured to receive the information associated with the available RISs is configured to receive the information associated with available RISs in response to the request regarding availability of RISs for communication with the WTRU.

3. The WTRU of claim 1 , wherein the received information associated with available RISs comprises at least one of a number of deployed RISs, RIS type, RIS mode, RIS phase resolution, RIS codebooks, RIS orientation, sub-surface grouping, or RIS area with increased near field effects.

4. The WTRU of claim 1 , wherein the request to initiate discovery of one or more of the available RISs comprises one or more of a traffic type, an expected reliability, a buffer size, an indication of primary use, an indication of previously used RISs, or location information associated with the WTRU.

5. The WTRU of claim 1 , wherein the at least one response message further comprises at least one of a time resource, port information, hopping pattern, repetition factor, spatial filter information, or time transmission properties.

6. The WTRU of claim 1 , wherein the request for service comprises one or more of an identifier associated with the at least one of the available RISs, configuration information for the at least one of the available RISs, or resource requirements.

7. The WTRU of claim 1 , wherein the identifier associated with the RIS comprises an implicit indication of the RIS.

8. The WTRU of claim 1 , wherein the processor is further configured to: on a condition that the type of RIS discovery is associated with uplink, transmit an uplink reference signal; and receive an indication of one or more RISs.

9. The WTRU of claim 1 , wherein the processor is further configured to: receive scheduling information associated with the at least one of the available RISs; and transmit, based on the scheduling information, RIS-based communication to the at least one of the available RISs.

10. The WTRU of claim 1 , wherein the processor configured to receive information associated with available RISs available for communication with the WTRU is further configured to receive the information associated with available RISs via a PDSCH transmission; wherein the processor configured to send, based on the received information, the request to initiate discovery of one or more of the available RISs is further configured to send the request to initiate discovery of one or more of the available RISs via PUSCH transmission. wherein the processor configured to receive the at least one response message is further configured to receive the at least one response message via PDSCH transmission.

11. A method for Reflective Intelligent Surfaces (RSIs) discovery comprising: receiving information associated with available Reflective Intelligent Surfaces (RISs) available for communication with a wireless transmit/receive unit (WTRU); sending, based on the received information, a request to initiate discovery of one or more of the available RISs; receiving at least one response message, the at least one response message comprising an indication of a number of RISs, RIS identifiers, a number of sub surfaces, frequency resources, near field information, and a type of RIS discovery; and on a condition that the type of RIS discovery is associated with downlink, performing a measurement for a configured reception occasion; reporting an index associated with the measurement; and receiving an identifier associated with a RIS; and sending a request for service from at least one of the available RISs.

12. The method of claim 11 , further comprising: sending a request regarding availability of RISs for communication with the WTRU, wherein receiving the information associated with the available RISs comprises receiving the information associated with available RISs in response to the request regarding availability of RISs for communication with the WTRU.

13. The method of claim 11, wherein the received information associated with available RISs comprises at least one of a number of deployed RISs, RIS type, RIS mode, RIS phase resolution, RIS codebooks, RIS orientation, sub-surface grouping, or RIS area with increased near field effects.

14. The method of claim 11, wherein the request to initiate discovery of one or more of the available RISs comprises one or more of a traffic type, an expected reliability, a buffer size, an indication of primary use, an indication of previously used RISs, or location information associated with the WTRU.

15. The method of claim 11, wherein the at least one response message further comprises at least one of a time resource, port information, hopping pattern, repetition factor, spatial filter information, or time transmission properties.

16. The method of claim 11, wherein the request for service comprises one or more of an identifier associated with the at least one of the available RISs, configuration information for the at least one of the available RISs, or resource requirements.

17. The method of claim 11, wherein the identifier associated with the RIS comprises an implicit indication of the RIS.

18. The method of claim 11, wherein the method further comprises: on a condition that the type of RIS discovery is associated with uplink, transmitting an uplink reference signal; and receiving an indication of one or more RISs.

19. The method of claim 11, wherein the method further comprises: receiving scheduling information associated with the at least one of the available RISs; and transmitting, based on the scheduling information, RIS-based communication to the at least one of the available RISs.

20. A wireless transmit and receive unit (WTRU), comprising: a processor configured to: receive information associated with available Reflective Intelligent Surfaces (RISs) available for communication with the WTRU; send, based on the received information, a request to initiate discovery of one or more of the available RISs; receive at least one response message, the at least one response message comprising an indication of a number of RISs, RIS identifiers, a number of sub surfaces, frequency resources, near field information, and a type of RIS discovery; and on a condition that the type of RIS discovery is associated with uplink, transmit an uplink reference signal; and receive an indication of one or more RISs; and send a request for service from at least one of the available RISs.