Configuration of reconfigurable smart surface (RIS) in wireless system

Abstract

A wireless transmit / receive unit (WTRU) may be configured to receive reconfigurable smart surface (RIS) discovery information. The RIS discovery information may indicate the presence of the RIS. The WTRU may perform one or more first measurements on one or more first signals to determine a first measurement value. The WTRU may determine that the first measurement is less than a threshold. The WTRU may transmit a reservation request to the RIS based on the first measurement being less than the threshold. The WTRU may perform one or more second measurements of one or more second signals received via the RIS to determine a second measurement value. The WTRU may determine that the second measurement is less than the threshold. The WTRU may transmit an RIS configuration update request to the RIS based on the second measurement being less than the threshold.

Description

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This patent application claims the benefit of U.S. Provisional Application No. 63 / 359,983, filed on July 11, 2022, and U.S. Provisional Application No. 63 / 468,954, filed on May 25, 2023, the entire contents of each of which are incorporated herein by reference in their entirety. Background Art

[0003] The present invention relates to the field of computing and communications, and more specifically, to methods, devices, systems, architectures, and interfaces for computing and communications in advanced or next generation wireless communication systems, including communications performed using new radio and / or new radio (NR) access technologies and communication systems. Such NR access and technologies (which may also be referred to as 5G and / or 6G, etc.) and / or other similar wireless communication systems and technologies may include features and / or technologies for reconfigurable smart surfaces (RIS). As described herein, the RIS may be able to adapt to radio environment conditions. For example, the RIS may be able to electronically control the propagation of radio frequency (RF) signals impinging on the surface of the RIS. NR downlink (DL) beam management (BM) is intended to adjust the transmit and receive point (TRP) transmit (TX) beam and the wireless transmit receive unit (WTRU) receive (RX) beam.

[0004] The RIS may include a programmable structure (e.g., a RIS controller) for controlling the propagation of electromagnetic (EM) waves, for example, by changing the electrical and magnetic properties of the surface of the RIS. By placing one or more RIS into an environment in which a wireless system is operating, the properties of a radio channel used for communication in the environment may be controlled. Control of the radio channel may change the wireless system design, where the radio channel is considered an uncontrollable entity that may distort the transmitted signal. In some implementations, the RIS may be placed (e.g., on a wall) so that signals from a first (e.g., predetermined) direction (e.g., from a base station or other network node) are directed toward the environment. Surfaces in such environments (e.g., walls, furniture, clothing, etc.) may, for example, include a metasurface-based RIS. In some implementations, the introduction of a RIS into a wireless communication system may provide coverage enhancement of a wireless link. For example, the RIS may be used to enhance the signal-to-noise ratio (SNR) at a receiver. For example, the radiation pattern of the RIS may be controlled so that the SNR may be improved at the receiver.

[0005] In order to properly control RIS to enhance network coverage, certain techniques for measuring channel quality may be implemented. For example, in some wireless systems, one or more frequency and / or time resources may be reserved for channel quality measurement. In some implementations, a channel state information reference signal (CSI-RS) for downlink channel sounding and a sounding reference signal (SRS) for uplink channel sounding may be defined separately (e.g., as described in the 5G NR standard). These time and / or frequency resources may be utilized to perform RIS control.

[0006] Signaling for initial cell access may also be defined (e.g., in the form of a synchronization signal (SS) block). For example, when the RIS is deployed in a wireless network (e.g., a 5G NR network), the SS block may be used to transmit information about the presence and / or attributes associated with the RIS to a wireless transmit receive unit (WTRU). In addition, beam establishment may be performed during a random access procedure (e.g., a 5G NR random access procedure). These resources may be employed to perform RIS control. As described herein, the RIS may be used to enhance the performance of any wireless system. Summary of the invention

[0007] A wireless transmit / receive unit (WTRU) may include a processor configured to receive reconfigurable intelligent surface (RIS) discovery information. For example, the RIS discovery information may include an indication of the presence of a RIS (e.g., in a cell). The WTRU may receive one or more first signals and perform one or more first measurements on the received one or more first signals. The WTRU may determine a first measurement value based on the first measurement. The WTRU may compare the first measurement value with a threshold and may, for example, determine that the first measurement value is less than the threshold. The WTRU may transmit a reservation request to the RIS based on the first measurement value being less than the threshold. The WTRU may receive one or more second signals and may perform one or more second measurements on the received one or more second signals. For example, the one or more second signals may be received via the RIS. The WTRU may determine a second measurement value based on the one or more second measurements. The WTRU may determine that the second measurement value is less than the threshold. The WTRU may transmit a RIS configuration update request (e.g., to the RIS) based on the second measurement value being less than the threshold. The WTRU may transmit the RIS reservation request and / or the RIS configuration update request as a first type of uplink control information (UCI).

[0008] The WTRU may also receive (e.g., via the RIS) one or more third signals and perform one or more third measurements on the received one or more third signals to determine a third measurement value. The WTRU may determine that the third measurement value is greater than the threshold. After determining that the third measurement value is greater than the threshold, the WTRU may perform data transmission via the RIS.

[0009] As described herein, the WTRU may receive RIS discovery information. The RIS discovery information may be received from a base station. Additionally or alternatively, the RIS discovery information may be received (e.g., reflected) via a RIS. For example, the RIS discovery information may be received in a physical broadcast channel (PBCH) transmission. BRIEF DESCRIPTION OF THE DRAWINGS

[0010] Figure 1A is a system diagram illustrating an example communication system in which one or more disclosed embodiments may be implemented;

[0011] Figure 1B is an example of an embodiment in which Figure 1A A system diagram of an example wireless transmit / receive unit (WTRU) for use within an illustrated communication system;

[0012] Figure 1C is an example of an embodiment in which Figure 1A A system diagram of an example Radio Access Network (RAN) and an example Core Network (CN) used within the illustrated communication system;

[0013] Figure 1D is an example of an embodiment in which Figure 1A A system diagram of another example RAN and another example CN used within the illustrated communication system;

[0014] Figure 2 An example system including a reconfigurable smart surface (RIS) is illustrated;

[0015] Figure 3 An example associated with the configuration of RIS is illustrated;

[0016] Figure 4 A and Figure 4 B illustrates an example associated with a signal-to-noise ratio (SNR) that may be achieved in a system including a RIS;

[0017] Figure 5 A and Figure 5 B illustrates other examples associated with may be implemented in a system including a RIS;

[0018] Figure 6illustrates examples associated with control signaling that may be used in a system including a RIS; and

[0019] Figure 7 An example protocol stack associated with a system including a RIS is illustrated. DETAILED DESCRIPTION

[0020] Figure 1A 1 is a diagram illustrating an example communication system 100 in which one or more disclosed embodiments may be implemented. The communication system 100 may be a multiple access system that provides content such as voice, data, video, messaging, broadcast, etc. to multiple wireless users. The communication system 100 may enable multiple wireless users to access such content through sharing of system resources (including wireless bandwidth). For example, the communication system 100 may employ one or more channel access methods such as code division multiple access (CDMA), time division multiple access (TDMA), frequency division multiple access (FDMA), orthogonal FDMA (OFDMA), single carrier FDMA (SC-FDMA), zero tail unique word DFT spread OFDM (ZT UW DTS-s OFDM), unique word OFDM (UW-OFDM), resource block filtered OFDM, filter bank multi-carrier (FBMC), spatial domain multiple access (SDMA), etc.

[0021] like Figure 1AAs shown, the communication system 100 may include wireless transmit / receive units (WTRUs) 102a, 102b, 102c, 102d, RAN 104 / 113, CN 106 / 115, public switched telephone network (PSTN) 108, Internet 110 and other networks 112, but it should be understood that the disclosed embodiments contemplate any number of WTRUs, base stations, networks, and / or network elements. Each of the WTRUs 102a, 102b, 102c, 102d may be any type of device configured to operate and / or communicate in a wireless environment. By way of example, the WTRUs 102a, 102b, 102c, 102d (any of which may be referred to as a “station” and / or “STA”) may be configured to send and / or receive wireless signals and may include user equipment (WTRU), a mobile station, a fixed or mobile subscriber unit, a subscription-based unit, a pager, a cellular phone, a personal digital assistant (PDA), a smart phone, a laptop, a netbook, a personal computer, a wireless sensor, a hotspot or Mi-Fi device, an Internet of Things (IoT) device, a watch or other wearable device, a head-mounted display (HMD), a vehicle, a drone, medical devices and applications (e.g., remote surgery), industrial devices and applications (e.g., robots and / or other wireless devices operating in an industrial and / or automated process chain environment), a consumer electronic device, a device operating on a commercial and / or industrial wireless network, etc. Any of the WTRUs 102a, 102b, 102c, and 102d may be interchangeably referred to as a WTRU.

[0022] The communication system 100 may also include a base station 114a and / or a base station 114b. Each of the base stations 114a, 114b may be any type of device that is configured to interface with at least one of the WTRUs 102a, 102b, 102c, 102d to facilitate access to one or more communication networks, such as the CN 106 / 115, the Internet 110, and / or other networks 112. By way of example, the base stations 114a, 114b may be a base transceiver station (BTS), a Node B, an eNode B, a Home Node B, a Home eNode B, a gNB, an NR Node B, a site controller, an access point (AP), a wireless router, and the like. Although the base stations 114a, 114b are each depicted as a single element, it should be appreciated that the base stations 114a, 114b may include any number of interconnected base stations and / or network elements.

[0023] The base station 114a may be part of the RAN 104 / 113, which may also include other base stations and / or network elements (not shown), such as a base station controller (BSC), a radio network controller (RNC), a relay node, etc. The base station 114a and / or the base station 114b may be configured to send and / or receive wireless signals on one or more carrier frequencies (which may be referred to as cells (not shown)). These frequencies may be in a licensed spectrum, an unlicensed spectrum, or a combination of licensed and unlicensed spectrum. A cell may provide coverage of wireless services to a specific geographic area, which may be relatively fixed or may change over time. The cell may be further divided into cell sectors. For example, a cell associated with the base station 114a may be divided into three sectors. Therefore, in one embodiment, the base station 114a may include three transceivers, i.e., one transceiver for each sector of the cell. In one 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 send and / or receive signals in a desired spatial direction.

[0024] 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).

[0025] More specifically, as noted above, the communication system 100 may be a multiple access system and may employ one or more channel access schemes such as CDMA, TDMA, FDMA, OFDMA, SC-FDMA, etc. For example, the base station 114a in the RAN 104 / 113 and the WTRUs 102a, 102b, 102c may implement a radio technology such as Universal Mobile Telecommunications System (UMTS) Terrestrial Radio Access (UTRA), which may use Wideband CDMA (WCDMA) to establish the air interface 115 / 116 / 117. WCDMA may include communication protocols such as High Speed ​​Packet Access (HSPA) and / or Evolved HSPA (HSPA+). HSPA may include High Speed ​​Downlink (DL) Packet Access (HSDPA) and / or High Speed ​​UL Packet Access (HSUPA).

[0026] In one embodiment, the base station 114a and the WTRUs 102a, 102b, 102c may implement a radio technology such as Evolved UMTS Terrestrial Radio Access (E-UTRA) that may establish the air interface 116 using Long Term Evolution (LTE) and / or Advanced LTE (LTE-A) and / or Advanced LTE Pro (LTE-A Pro).

[0027] In one 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).

[0028] In one embodiment, the base station 114a and the WTRUs 102a, 102b, 102c may implement multiple radio access technologies. For example, the base station 114a and the WTRUs 102a, 102b, 102c may together implement LTE radio access and NR radio access, for example using dual connectivity (DC) principles. Thus, the air interface utilized by the WTRUs 102a, 102b, 102c may be characterized by multiple types of radio access technologies and / or transmissions transmitted to / from multiple types of base stations (e.g., eNBs and gNBs).

[0029] 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), etc.

[0030] Figure 1AThe base station 114b in the example may be, for example, a wireless router, a Home NodeB, a Home eNodeB, or an access point, and may utilize any suitable RAT to facilitate wireless connectivity in a local area, such as a business location, a home, a vehicle, a campus, an industrial facility, an air corridor (e.g., for use by drones), a road, and the like. In one embodiment, the base station 114b and the WTRUs 102c, 102d may implement a radio technology such as IEEE 802.11 to establish a wireless local area network (WLAN). In one embodiment, the base station 114b and the WTRUs 102c, 102d may implement a radio technology such as IEEE 802.15 to establish a wireless personal area network (WPAN). In another embodiment, the base station 114b and the WTRUs 102c, 102d may utilize a cellular-based RAT (e.g., WCDMA, CDMA2000, GSM, LTE, LTE-A, LTE-A Pro, NR, etc.) to establish a micro-micro cell base station or a femto cell base station. As Figure 1A As shown, base station 114b may have a direct connection to Internet 110. Therefore, base station 114b may not need to access Internet 110 via CN 106 / 115.

[0031] The RAN 104 / 113 may be in communication with the CN 106 / 115, which may be any type of network configured to provide voice, data, applications and / or Voice over Internet Protocol (VoIP) services to one or more of the WTRUs 102a, 102b, 102c, 102d. The data may have different quality of service (QoS) requirements, such as different throughput requirements, latency requirements, error tolerance requirements, reliability requirements, data throughput requirements, mobility requirements, etc. The CN 106 / 115 may provide call control, billing services, mobile location-based services, prepaid calling, Internet connectivity, video distribution, etc., and / or perform high-level security functions, such as user authentication. Although not described in detail in the text and video, the CN 106 / 115 may be configured to provide voice, data, applications and / or Voice over Internet Protocol (VoIP) services to one or more of the WTRUs 102a, 102b, 102c, 102d. The data may have different quality of service (QoS) requirements, such as different throughput requirements, latency requirements, error tolerance requirements, reliability requirements, data throughput requirements, mobility requirements, etc. The CN 106 / 115 may provide call control, billing services, mobile location-based services, prepaid calling, Internet connectivity, video distribution, etc., and / or perform high-level security functions, such as user authentication. Figure 1A Although not shown in the figure, it will be appreciated that the RAN 104 / 113 and / or the CN 106 / 115 may be in direct or indirect communication with other RANs that employ the same RAT as the RAN 104 / 113 or a different RAT. For example, in addition to being connected to the RAN 104 / 113, which may utilize NR radio technology, the CN 106 / 115 may also be in communication with another RAN (not shown) that employs GSM, UMTS, CDMA2000, WiMAX, E-UTRA, or WiFi radio technology.

[0032] The CN 106 / 115 may also act as a gateway for the WTRUs 102a, 102b, 102c, 102d to access the PSTN 108, the Internet 110, and / or other networks 112. The PSTN 108 may include a circuit-switched telephone network that provides plain old telephone service (POTS). The Internet 110 may include a global system of interconnected computer networks and devices that use common communication protocols, such as the Transmission Control Protocol (TCP), the User Datagram Protocol (UDP), and / or the Internet Protocol (IP) in the TCP / IP Internet protocol suite. The networks 112 may include wired communication networks and / or wireless communication networks owned and / or operated by other service providers. For example, the networks 112 may include another CN connected to one or more RANs, which may employ the same RAT as the RAN 104 / 113 or a different RAT.

[0033] Some or all of the WTRUs 102a, 102b, 102c, 102d in the communication system 100 may include multi-mode capabilities (e.g., the WTRUs 102a, 102b, 102c, 102d may include multiple transceivers for communicating with different wireless networks via different wireless links). Figure 1A The illustrated WTRU 102c may be configured to communicate with the base station 114a, which may employ a cellular-based radio technology, and with the base station 114b, which may employ an IEEE 802 radio technology.

[0034] Figure 1B is a system diagram illustrating an example WTRU 102. Figure 1B As shown, the WTRU 102 may include, among other things, a processor 118, a transceiver 120, a transmit / receive element 122, a speaker / microphone 124, a keypad 126, a display / touchpad 128, non-removable memory 130, removable memory 132, a power source 134, a global positioning system (GPS) chipset 136, and / or other peripherals 138. It will be appreciated that the WTRU 102 may include any sub-combination of the foregoing elements while remaining consistent with an embodiment.

[0035] The processor 118 may be a general purpose processor, a special purpose processor, a conventional processor, a digital signal processor (DSP), a plurality of microprocessors, one or more microprocessors associated with a DSP core, a controller, a microcontroller, an application specific integrated circuit (ASIC), a field programmable gate array (FPGA) circuit, any other type of integrated circuit (IC), a state machine, etc. The processor 118 may perform signal decoding, data processing, power control, input / output processing, and / or any other functionality that enables the WTRU 102 to operate in a wireless environment. The processor 118 may be coupled to the transceiver 120, which may be coupled to the transmit / receive element 122. Although Figure 1B The processor 118 and the transceiver 120 are depicted as separate components, but it is understood that the processor 118 and the transceiver 120 may be integrated together in an electronic package or chip.

[0036] The send / receive element 122 may be configured to send a signal to a base station (e.g., base station 114a) or receive a signal from the base station by an air interface 116. For example, in one embodiment, the send / receive element 122 may be an antenna configured to send and / or receive an RF signal. In one embodiment, the send / receive element 122 may be a transmitter / detector configured to send and / or receive, for example, IR, UV or visible light signals. In another embodiment, the send / receive element 122 may be configured to send and / or receive both RF signals and optical signals. It should be understood that the send / receive element 122 may be configured to send and / or receive any combination of wireless signals.

[0037] Although the transmit / receive element 122 Figure 1B Although depicted as a single element in the figure, the WTRU 102 may include any number of transmit / receive elements 122. More specifically, the WTRU 102 may employ MIMO technology. Thus, in one embodiment, the WTRU 102 may include two or more transmit / receive elements 122 (e.g., multiple antennas) for transmitting and receiving wireless signals over the air interface 116.

[0038] The transceiver 120 may be configured to modulate signals to be transmitted by the transmit / receive element 122 and to demodulate signals received by the transmit / receive element 122. As noted above, the WTRU 102 may have multi-mode capabilities. For example, the transceiver 120 may include multiple transceivers for enabling the WTRU 102 to communicate via multiple RATs, such as NR and IEEE 802.11.

[0039] The processor 118 of the WTRU 102 may be coupled to and may receive user input data from a speaker / microphone 124, a keypad 126, and / or a display / touchpad 128 (e.g., a liquid crystal display (LCD) display unit or an organic light emitting diode (OLED) display unit). The processor 118 may also output user data to the speaker / microphone 124, the keypad 126, and / or the display / touchpad 128. In addition, the processor 118 may access information from and store data in any type of suitable memory, such as a non-removable memory 130 and / or a removable memory 132. The non-removable memory 130 may include a random access memory (RAM), a read-only memory (ROM), a hard disk, or any other type of memory storage device. The removable memory 132 may include a subscriber identity module (SIM) card, a memory stick, a secure digital (SD) memory card, and the like. In other embodiments, the processor 118 may access information from and store data in a memory that is not physically located on the WTRU 102, such as on a server or a home computer (not shown).

[0040] The processor 118 may receive power from the power source 134, and may be configured to distribute and / or control power to the other components in the WTRU 102. The power source 134 may be any suitable device for powering the WTRU 102. For example, the power source 134 may include one or more dry cell batteries (e.g., nickel-cadmium (NiCd), nickel-zinc (NiZn), nickel-metal hydride (NiMH), lithium-ion (Li-ion), etc.), solar cells, fuel cells, etc.

[0041] The processor 118 may also be coupled to the GPS chipset 136, which may be configured to provide location information (e.g., longitude and latitude) regarding the current location of the WTRU 102. In addition to or in lieu of the information from the GPS chipset 136, the WTRU 102 may receive location information from a base station (e.g., base stations 114a, 114b) over the air interface 116 and / or determine its location based on the timing of signals received from two or more nearby base stations. It will be appreciated that the WTRU 102 may acquire location information by any suitable location-determination method while remaining consistent with an embodiment.

[0042] The processor 118 may also be coupled to other peripherals 138, which may include one or more software modules and / or hardware modules that provide additional features, functionality, and / or wired or wireless connectivity. For example, the peripherals 138 may include an accelerometer, an electronic compass, a satellite transceiver, a digital camera (for photos and / or video), a universal serial bus (USB) port, a vibration device, a television transceiver, a hands-free headset, module, a frequency modulation (FM) radio unit, a digital music player, a media player, a video game player module, an Internet browser, a virtual reality and / or augmented reality (VR / AR) device, an activity tracker, etc. Peripheral device 138 may include one or more sensors, which may be one or more of the following: 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.

[0043] The WTRU 102 may include a full-duplex radio for which transmission and reception of some or all signals (e.g., associated with specific subframes for both UL (e.g., for transmission) and downlink (e.g., for reception)) may be concurrent and / or simultaneous. The full-duplex radio may include an interference management unit 139 for reducing and / or substantially eliminating self-interference via signal processing performed by hardware (e.g., a choke) or via a processor (e.g., a separate processor (not shown) or via the processor 118). In one embodiment, the WRTU 102 may include a half-duplex radio for which transmission and reception of some or all signals (e.g., associated with specific subframes for both UL (e.g., for transmission) or downlink (e.g., for reception)) may be concurrent and / or simultaneous.

[0044] Figure 1C 1 is a system diagram illustrating the RAN 104 and the CN 106 in accordance with an embodiment. As noted above, the RAN 104 may employ an E-UTRA radio technology to communicate with the WTRUs 102a, 102b, 102c over the air interface 116. The RAN 104 may also be in communication with the CN 106.

[0045] The RAN 104 may include evolved Node-Bs 160a, 160b, 160c, though it will be appreciated that the RAN 104 may include any number of evolved Node-Bs while remaining consistent with an embodiment. The evolved Node-Bs 160a, 160b, 160c may each include one or more transceivers for communicating with the WTRUs 102a, 102b, 102c over the air interface 116. In one embodiment, the evolved Node-Bs 160a, 160b, 160c may implement MIMO technology. Thus, the evolved Node-B 160a, for example, may use multiple antennas to transmit wireless signals to and / or receive wireless signals from the WTRU 102a.

[0046] Each of the evolved Node Bs 160a, 160b, 160c may be associated with a particular cell (not shown) and may be configured to handle radio resource management decisions, handover decisions, scheduling of users in the UL and / or DL, etc. Figure 1C As shown, the eNode-Bs 160a, 160b, 160c may communicate with one another via an X2 interface.

[0047] Figure 1C The illustrated CN 106 may include a mobility management entity (MME) 162, a serving gateway (SGW) 164, and a packet data network (PDN) gateway (or PGW) 166. While each of the foregoing elements is depicted as being part of the CN 106, it should be understood that any of these elements may be owned and / or operated by an entity other than the CN operator.

[0048] The MME 162 may be connected to each of the evolved Node-Bs 162a, 162b, 162c in the RAN 104 via an S1 interface and may serve as a control node. For example, the MME 162 may be responsible for authenticating users of the WTRUs 102a, 102b, 102c, bearer activation / deactivation, selecting a particular serving gateway during an initial attach of the WTRUs 102a, 102b, 102c, etc. The MME 162 may provide a control plane function for switching between the RAN 104 and other RANs (not shown) that employ other radio technologies, such as GSM and / or WCDMA.

[0049] The SGW 164 may be connected to each of the evolved Node-Bs 160a, 160b, 160c in the RAN 104 via an S1 interface. The SGW 164 may generally route and forward user data packets to / from the WTRUs 102a, 102b, 102c. The SGW 164 may perform other functions, such as anchoring the user plane during an inter-evolved Node-B handover, triggering paging when DL data is available for the WTRUs 102a, 102b, 102c, managing and storing the context of the WTRUs 102a, 102b, 102c, and the like.

[0050] 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.

[0051] The CN 106 may facilitate communications with other networks. For example, the CN 106 may provide the WTRUs 102a, 102b, 102c with access to circuit-switched networks, such as the PSTN 108, to facilitate communications between the WTRUs 102a, 102b, 102c and traditional land-line communications devices. For example, the CN 106 may include, or may be in communication with, an IP gateway (e.g., an IP Multimedia Subsystem (IMS) server) that acts as an interface between the CN 106 and the PSTN 108. In addition, the CN 106 may provide the WTRUs 102a, 102b, 102c with access to other networks 112, which may include other wired networks and / or wireless networks owned and / or operated by other service providers.

[0052] Although the WTRU Figures 1A to 1D Although described as wireless terminals, it is contemplated that in certain representative embodiments, such terminals may (eg, temporarily or permanently) use a wired communications interface with a communications network.

[0053] In a representative embodiment, the other network 112 may be a WLAN.

[0054] A WLAN in infrastructure basic service set (BSS) mode may have an access point (AP) for a BSS and one or more stations (STAs) associated with the AP. The AP may have access or an interface to a distribution system (DS) or another type of wired / wireless network that carries traffic to and / or carries traffic away from the BSS. Traffic originating from outside the BSS and destined for the STA may be reached by the AP and may be delivered to the STA. Traffic originating from the STA and destined for a target outside the BSS may be transmitted to the AP to be delivered to the corresponding target. Traffic between STAs within the BSS may be transmitted by the AP, for example, wherein the source STA may transmit traffic to the AP, and the AP may deliver traffic to the target STA. Traffic between STAs within the BSS may be considered and / or referred to as point-to-point traffic. Point-to-point traffic may be transmitted between the source STA and the target STA (e.g., directly between them) using a direct link setup (DLS). In certain representative embodiments, the DLS may use 802.11e DLS or 802.11z tunnel DLS (TDLS). A WLAN using an independent BSS (IBSS) mode may not have an AP, and STAs within or using the IBSS (eg, all STAs in the STA) may communicate directly with each other. The IBSS communication mode may sometimes be referred to herein as an "ad hoc" communication mode.

[0055] When using the 802.11ac infrastructure operation mode or a similar operation mode, the AP may send beacons on a fixed channel (such as a primary channel). The primary channel may be a fixed width (e.g., a 20 MHz wide bandwidth) or a width dynamically set via signaling. The primary channel may be a working channel of the BSS and may be used by the STA to establish a connection with the AP. In certain representative embodiments, carrier sense multiple access / collision avoidance (CSMA / CA) may be implemented, for example, in an 802.11 system. For CSMA / CA, a STA (e.g., each STA) (including the AP) may listen to the primary channel. If the primary channel is listened / 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.

[0056] High throughput (HT) STAs may communicate using a 40 MHz wide channel, for example, via a combination of a primary 20 MHz channel and adjacent or non-adjacent 20 MHz channels to form a 40 MHz wide channel.

[0057] Very high throughput (VHT) STA can support 20MHz, 40MHz, 80MHz and / or 160MHz wide channels. 40MHz channels and / or 80MHz channels can be formed by combining continuous 20MHz channels. 160MHz channels can be formed by combining 8 continuous 20MHz channels, or by combining two non-continuous 80MHz channels (this can be called 80+80 configuration). For 80+80 configuration, after channel coding, the data can pass through a segment parser that can divide the data into two streams. Each stream can be processed by inverse fast Fourier transform (IFFT) and time domain processing separately. These streams can be mapped to two 80MHz channels, and the data can be sent by the transmitter STA. At the receiver of the receiver STA, the above-mentioned operation for the 80+80 configuration can be reversed, and the combined data can be transmitted to the medium access control (MAC).

[0058] 802.11af and 802.11ah support operating modes below 1GHz. Channel operating bandwidths and carriers are reduced in 802.11af and 802.11ah relative to those used in 802.11n and 802.11ac. 802.11af supports 5MHz, 10MHz, and 20MHz bandwidths in the TV White Space (TVWS) spectrum, and 802.11ah supports 1MHz, 2MHz, 4MHz, 8MHz, and 16MHz bandwidths using non-TVWS spectrum. According to a representative embodiment, 802.11ah may support instrument type control / machine type communications, such as MTC devices in macro coverage areas. MTC devices may have certain capabilities, such as limited capabilities, including support for (e.g., only support for) certain bandwidths and / or limited bandwidths. MTC devices may include batteries with battery life above a threshold (e.g., to maintain very long battery life).

[0059] WLAN systems that can support multiple channels and channel bandwidths (such as 802.11n, 802.11ac, 802.11af, and 802.11ah) include channels that can be designated as primary channels. The primary channel may have a bandwidth equal to the maximum common operating bandwidth supported by all STAs in the BSS. The bandwidth of the primary channel may be set and / or limited by a STA (which supports the minimum bandwidth operation mode) from all STAs operating in the BSS. In the example of 802.11ah, for STAs (e.g., MTC-type devices) that support (e.g., only support) a 1MHz mode, the primary channel may be 1MHz wide, even if the AP and other STAs in the BSS support 2MHz, 4MHz, 8MHz, 16MHz, and / or other channel bandwidth operation modes. Carrier sensing and / or network allocation vector (NAV) settings may depend on the state of the primary channel. If the primary channel is busy, for example, because a STA (supporting only a 1MHz operation mode) is sending to the AP, the entire available band may be considered busy even if most of the band remains idle and may be available.

[0060] In the United States, the available frequency band for 802.11ah is 902MHz to 928MHz. In South Korea, the available frequency band is 917.5MHz to 923.5MHz. In Japan, the available frequency band is 916.5MHz to 927.5MHz. The total bandwidth available for 802.11ah is 6MHz to 26MHz, depending on the country code.

[0061] Figure 1D 1 is a system diagram illustrating the RAN 113 and the CN 115 in accordance with an embodiment. As noted above, the RAN 113 may employ NR radio technology to communicate with the WTRUs 102a, 102b, 102c over the air interface 116. The RAN 113 may also be in communication with the CN 115.

[0062] The RAN 113 may include gNBs 180a, 180b, 180c, though it will be appreciated that the RAN 113 may include any number of gNBs while remaining consistent with an embodiment. The gNBs 180a, 180b, 180c may each include one or more transceivers for communicating with the WTRUs 102a, 102b, 102c over the air interface 116. In one embodiment, the gNBs 180a, 180b, 180c may implement MIMO technology. For example, the gNBs 180a, 180b may utilize beamforming to send signals to and / or receive signals from the gNBs 180a, 180b, 180c. Thus, the gNB 180a may, for example, use multiple antennas to send wireless signals to and / or receive wireless signals from the WTRU 102a. In one 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 an unlicensed spectrum, while the remaining component carriers may be on a licensed spectrum. In one embodiment, the gNBs 180a, 180b, 180c may implement coordinated multi-point (CoMP) technology. For example, the WTRU 102a may receive coordinated transmissions from the gNB 180a and gNB 180b (and / or gNB 180c).

[0063] The WTRUs 102a, 102b, 102c may communicate with the gNBs 180a, 180b, 180c using transmissions associated with parameter sets that may be scalable. For example, OFDM symbol spacing and / or OFDM subcarrier spacing may vary for different transmissions, different cells, and / or different portions of the wireless transmission spectrum. The WTRUs 102a, 102b, 102c may communicate with the gNBs 180a, 180b, 180c using subframes or Transmission Time Intervals (TTIs) of varying or scalable lengths (e.g., containing varying numbers of OFDM symbols and / or varying absolute time lengths over time).

[0064] The gNBs 180a, 180b, 180c may be configured to communicate with the WTRUs 102a, 102b, 102c in a standalone configuration and / or a non-standalone configuration. In a standalone configuration, the WTRUs 102a, 102b, 102c may communicate with the gNBs 180a, 180b, 180c while not accessing other RANs (e.g., such as the eNodeBs 160a, 160b, 160c). In a standalone configuration, the WTRUs 102a, 102b, 102c may use one or more of the gNBs 180a, 180b, 180c as mobility anchor points. In a standalone configuration, the WTRUs 102a, 102b, 102c may communicate with the gNBs 180a, 180b, 180c using signals in an unlicensed band. In a non-standalone configuration, the WTRUs 102a, 102b, 102c may communicate / connect with the gNB 180a, 180b, 180c while also communicating / connecting with another RAN, such as the eNodeB 160a, 160b, 160c. For example, the WTRUs 102a, 102b, 102c may implement the DC principle to communicate with one or more gNBs 180a, 180b, 180c and one or more eNodeBs 160a, 160b, 160c substantially simultaneously. In a non-standalone configuration, the eNodeB 160a, 160b, 160c may act as a mobility anchor for the WTRUs 102a, 102b, 102c, and the gNB 180a, 180b, 180c may provide additional coverage and / or throughput for serving the WTRUs 102a, 102b, 102c.

[0065] Each of the gNBs 180a, 180b, 180c may be associated with a specific cell (not shown) and may be configured to handle radio resource management decisions, handover decisions, scheduling of users in UL and / or DL, support of network slicing, dual connectivity, interworking between NR and E-UTRA, routing of user plane data towards a user plane function (UPF) 184a, 184b, routing of control plane information towards an access and mobility management function (AMF) 182a, 182b, etc. Figure 1D As shown, gNBs 180a, 180b, and 180c may communicate with each other via an Xn interface.

[0066] Figure 1DThe illustrated CN 115 may include at least one AMF 182a, 182b, at least one UPF 184a, 184b, at least one session management function (SMF) 183a, 183b, and possible data networks (DNs) 185a, 185b. Although each of the foregoing elements is depicted as part of the CN 115, it should be understood that any of these elements may be owned and / or operated by an entity other than the CN operator.

[0067] The AMF 182a, 182b may be connected to one or more of the gNBs 180a, 180b, 180c in the RAN 113 via the N2 interface and may act as a control node. For example, the AMF 182a, 182b may be responsible for authenticating users of the WTRU 102a, 102b, 102c, supporting network slicing (e.g., handling different protocol data unit (PDU) sessions with different requirements), selecting a specific SMF 183a, 183b, management of registration areas, termination of NAS signaling, mobility management, etc. The AMF 182a, 182b may use network slicing to customize CN support for the WTRU 102a, 102b, 102c based on the type of services utilized by the WTRU 102a, 102b, 102c. For example, different network slices may be established for different use cases, such as services relying on ultra-reliable low latency (URLLC) access, services relying on enhanced mobile broadband (eMBB) access, services for machine type communication (MTC) access, etc. The AMF 162 may provide a control plane function for switching between the RAN 113 and other RANs (not shown) that employ other radio technologies, such as LTE, LTE-A, LTE-A Pro, and / or non-3GPP access technologies, such as WiFi.

[0068] The SMF 183a, 183b may be connected to the AMF 182a, 182b in the CN 115 via the N11 interface. The SMF 183a, 183b may also be connected to the UPF 184a, 184b in the CN 115 via the N4 interface. The SMF 183a, 183b may select and control the UPF 184a, 184b, and configure traffic routing through the UPF 184a, 184b. The SMF 183a, 183b may perform other functions such as managing and allocating WTRU IP addresses, managing PDU sessions, controlling policy enforcement and QoS, providing downlink data notifications, etc. The PDU session type may be IP-based, non-IP-based, Ethernet-based, etc.

[0069] The UPF 184a, 184b may be connected to one or more of the gNBs 180a, 180b, 180c in the RAN 113 via the N3 interface, which may provide the WTRUs 102a, 102b, 102c with access to packet-switched networks, such as the Internet 110, to facilitate communications between the WTRUs 102a, 102b, 102c and IP-enabled devices. The UPF 184, 184b may perform other functions, such as routing and forwarding packets, enforcing user plane policies, supporting multi-homed PDU sessions, handling user plane QoS, buffering downlink packets, providing mobility anchoring, etc.

[0070] The CN 115 may facilitate communications with other networks. For example, the CN 115 may include or may communicate with an IP gateway (e.g., an IP Multimedia Subsystem (IMS) server) that acts as an interface between the CN 115 and the PSTN 108. In addition, the CN 115 may provide the WTRUs 102a, 102b, 102c with access to other networks 112, which may include other wired networks and / or wireless networks owned and / or operated by other service providers. In one embodiment, the WTRUs 102a, 102b, 102c may be connected to local data networks (DNs) 185a, 185b via the UPF 184a, 184b via the N3 interface to the UPF 184a, 184b and the N6 interface between the UPF 184a, 184b and the DN 185a, 185b.

[0071] Given that Figures 1A to 1D as well as Figures 1A to 1D , one or more or all of the functions described herein for one or more of the following may be performed by one or more simulation devices (not shown): WTRU 102a-102d, base station 114a-114b, evolved Node B 160a-160c, MME 162, SGW 164, PGW 166, gNB 180a-180c, AMF 182a-182ab, UPF 184a-184b, SMF 183a-183b, DN 185a-185b and / or any other device described herein. The simulation device may be one or more devices configured to emulate one or more or all of the functions described herein. For example, the simulation device may be used to test other devices and / or simulate network and / or WTRU functions.

[0072] The simulation device may be designed to implement one or more tests of other devices in a laboratory environment and / or in an operator network environment. For example, one or more simulation devices may perform one or more functions or all functions while being fully or partially implemented and / or deployed as part of a wired and / or wireless communication network in order to test other devices within the communication network. One or more simulation devices may perform one or more functions or all functions while being temporarily implemented / deployed as part of a wired and / or wireless communication network. The simulation device may be directly coupled to another device for the purpose of testing and / or performing tests using over-the-air wireless communications.

[0073] One or more simulation devices can perform one or more (including all) functions without being implemented / deployed as part of a wired and / or wireless communication network. For example, the simulation device can be used in a test scenario in a test laboratory and / or a non-deployed (e.g., testing) wired and / or wireless communication network to implement testing of one or more components. One or more simulation devices can be test equipment. Direct RF coupling and / or wireless communication via an RF circuit system (e.g., which can include one or more antennas) can be used by the simulation device to send and / or receive data.

[0074] In some implementations, the link quality in a wireless system may be degraded (e.g., due to shadowing, blockage, etc.) to support selected applications / services. RIS may be used to route electromagnetic waves around obstacles, which may cause shadowing / blocking. To route signals around obstacles, RIS may be configured to reflect or refract signals in appropriate directions. However, RIS configuration may require channel estimation and optimization techniques, which may be computationally complex.

[0075] One or more techniques associated with RIS configuration are provided herein. As described herein, RIS confirmations can be based on one or more quality metric measurements (e.g., signal-to-noise ratio (SNR), reference signal received power (RSRP), channel quality indicator (CQI), ACK-NACK, etc.). For example, instead of performing channel estimation and spectrum and / or energy efficiency optimization techniques (e.g., which may be computationally complex), the RIS can be configured to achieve (e.g., obtain, maintain, etc.) a predetermined quality level, which can be measured using a quality metric measurement such as SNR.

[0076] The present patent application discloses a method for facilitating RIS-assisted communication, for example, by providing downlink control information (DCI) and / or one or more transmission configuration indicators (TCIs) (e.g., two sets of DCIs and two sets of TCIs) for a gNB-WTRU link and a RIS-WTRU link.

[0077] One or more techniques can be provided for achieving a target quality level (e.g., SNR) using RIS. For example, one or more techniques (e.g., computationally simple techniques) can be provided to enhance / enable RIS coverage of a wireless system. One or more of the following can be applied.

[0078] Using RIS to improve or enable communication between a WTRU and a gNB (e.g., or a mobile terminal and a base station, access point, etc.) may be performed using signaling between the network, the WTRU, and one or more RIS elements. Configuration of RIS may include the exchange of information and the sending of control signaling between the WTRU, RIS elements, and / or the network.

[0079] RIS configuration (e.g., as a technique to optimize spectrum or energy efficiency) may include performing channel estimation on a channel between a transmitter and the RIS and a channel between the RIS and a receiver. Channel estimation performed for RIS configuration may be computationally intensive. For example, channel estimation may include the transmission of a training sequence, and the receiver may receive and store the received samples during training (e.g., before the optimization problem can be solved). In addition, in order to increase (e.g., maximize) the possible gain of using RIS in a wireless system, RIS may form a narrow beam pattern, for example, to pick up a signal from a transmitter node and reflect or refract the signal toward a receiver node. RIS may additionally or alternatively form a narrow beam pattern to enhance the coverage of a wireless link. In order to form a narrow beam, RIS may perform a search process, which may increase (e.g., cause excessive) overhead on a RIS auxiliary link. The overhead associated with RIS configuration may affect (e.g., impair) the potential gain provided by RIS. In some specific implementations, channel estimation and associated search processes for RIS configuration may be simplified, for example, by using a majority voting algorithm (e.g., to maximize the received SNR).

[0080] The techniques described herein may be used to simplify and accelerate the RIS configuration process. For example, the techniques described herein may include obtaining and / or maintaining a predetermined channel quality (e.g., measured by SNR and / or any other suitable performance indicator). However, certain other implementations do not consider the initial access scenario described herein. Certain other implementations also do not consider that the RIS configuration may be based on measurements performed at the WTRU, as described herein.

[0081] A system model associated with a wireless system including RIS 204 may be provided. One or more of the following may apply. For example, Figure 2 An example system 200 including a RIS 202 is illustrated. Figure 2As shown, system 202 may include: one or more (e.g., two, three, four) single antenna nodes, RIS 202, and an associated RIS controller. RIS 202 may be a standalone unit, part of a network, and / or controlled (e.g., fully controlled) by the WTRU. RIS 202 may be connected to a RIS controller, which may be configured to communicate with a receiving node. RIS controller may also be part of RIS 202. For example, a receiving node may be configured to provide feedback regarding the configuration of RIS 202 via the RIS controller. RIS controller may be located at a RIS 202 site. Figure 2 As shown, for example, even if the link (e.g., direct link) between the nodes is blocked (e.g., completely blocked), the node can communicate with the RIS controller. In some scenarios, the RIS controller may not be co-located with the RIS 202. For example, the RIS controller can be deployed at any location as long as the measurement results (e.g., received signal power, SNR, etc.) or the performance indicator calculated based on the measurement results can be transmitted from the receiving node to the RIS controller / transmitted from the RIS controller, and the RIS controller can configure the RIS 202 hardware. As described herein, a single RIS controller can control more than one RIS. Alternatively, one or more RIS controllers can control a single RIS. For example, if the RIS controller is not co-located with the RIS 202, an additional connection between the RIS 202 and the RIS controller can be used. Control plane messages can be sent / received between the RIS 202 and the node. The RIS controller can be equipped with a low-power, low-complexity transceiver. The control plane messages (e.g., RIS control plane messages) sent / received between RIS 202 and the node may be different from the messages communicated on the control plane of the existing wireless system, and the RIS control plane 212 may be implemented independently of the served wireless system and / or integrated into the served wireless system. The RIS control plane may include a radio resource control layer (RRC) responsible for configuring the lower layers. Figure 2 As shown, if there is a link (e.g., a direct link) between node 1 206 and node 2 208, the nodes can also share control information directly with each other. The user plane 210 can carry data sent throughout the system 200. The user plane 210 can include one or more of the following sublayers: PDCP (Packet Data Convergence Protocol), RLC (Radio Link Control), and Medium Access Control (MAC).

[0082] RIS202 can be configured based on a channel quality indicator (e.g., received SNR). Although SNR is used as an example channel quality indicator to describe the technology herein, other similar channel quality indicators may be used in addition or alternatively. One or more of the following items may be applied. An SNR threshold (e.g., requirement) may be defined at a receiving node (RX node). For example, an SNR threshold may be defined based on the requirements of the application or service used (e.g., an SNR threshold may be defined from an upper layer to a physical layer). The SNR threshold may be defined in addition or alternatively based on a previous SNR value measured by the RX node. For example, if the RX node detects a drop in the measured SNR value, the RX node may initiate a RIS configuration process. The RIS configuration process may be initiated at the physical layer. Regardless of the source of the SNR threshold, the RIS configuration techniques described herein may be applied. When the SNR threshold is not met at the link between node 1 206 and node 2 208, RIS202 may be reserved for the connection. In some implementations, the RX node can communicate with the RIS controller to control (eg, directly control) the RIS 202. The RIS controller can additionally or alternatively notify / inform the sender node (TX node) about the use of the RIS.

[0083] Figure 3 An example associated with the RIS configuration process is illustrated. One or more of the following may be applied. The measured SNR may be less than an SNR threshold. For example, an SNR threshold may be defined based on link quality requirements (e.g., data rate). The RX node may measure the SNR of an input signal. For example, a signal designed for channel estimation purposes and noise estimation purposes may be used to measure the SNR (e.g., also referred to as a reference signal or training signal, such as a channel state information reference signal (CSI-RS), a sounding reference signal (SRS), etc.). The reference signal may be multiplexed with user and other data symbols. Additionally or alternatively, the reference signal may be sent as part of a preamble.

[0084] like Figure 3As shown, at step 302, the WTRU may detect that the signal-to-noise ratio (SNR) has dropped below a threshold. At step 304, the WTRU may reserve the RIS, for example, by transmitting a message to the RIS controller 204 or the RIS 202. One or more of the following may apply. When the measured SNR is below the SNR threshold, the Rx node may transmit a request to the RIS controller 204 to reserve the RIS. If the RIS is not used by any other node pair, the request to use the RIS transmitted by the RX node may be granted. The RIS controller 204 may notify the TX node (e.g., gNB) of the use of the RIS. At step 306, the RIS controller 204 may instruct the TX node to send a training signal and / or a reference signal to be used for SNR measurement. For example, the RIS controller 204 may instruct the TX node to send the training signal and / or the reference signal with the shortest periodicity allowed by the system 202.

[0085] At step 308, the configuration of the RIS may be changed. One or more of the following may apply. The configuration of the RIS may be changed to synchronize with the transmission of the training signal by the TX node. For example, the configuration of the RIS may refer to a process (e.g., beamforming) by which the RIS associated with a parameter is configured to reflect and / or refract a signal impinging on the RIS. The parameter may include one or more of the following: phase response, amplitude response, phase and amplitude response, unit cell grouping (sub-surface), and / or switch information. The parameters associated with the RIS may be changed (e.g., modified / updated) until a measured quality metric (e.g., SNR) associated with the training signal is greater than or equal to a threshold quality metric, as further described herein. Further details associated with the configuration of the RIS may depend on the RIS implementation.

[0086] At step 310, a training signal may be received (e.g., by a WTRU) and an SNR may be calculated. One or more of the following may apply. At step 312, if the RX node (e.g., WTRU) calculates that the SNR is below a threshold and has not exceeded a configured period, the RX node may continue to receive training signal transmissions, change the RIS configuration, and measure the SNR of its incoming signal.

[0087] At step 314, the measured SNR may be greater than the SNR threshold. If the measured SNR is greater than the SNR threshold, then at step 316, the RX node may inform / notify the RIS controller 204 that the measured SNR is greater than the SNR threshold. Configuration of the RIS may be stopped, and data may be sent using the RIS based on the RIS configuration associated with the measured SNR being greater than the SNR threshold.

[0088] At step 318, the measured SNR may be less than an SNR threshold (e.g., less than an SNR threshold that is longer than a deadline, which may be defined by the system). The deadline may be set, for example, by the WTRU (e.g., for time-critical communications), a RIS controller, and / or a network (e.g., defined in a radio link control or radio resource control layer). If none of the RIS configurations tested within a deadline (e.g., a deadline set by the system) results in a measured SNR greater than a threshold SNR, then at step 320, the RIS configuration process may stop and the RIS may be released. In certain scenarios, the deadline (e.g., for a timer) may be configured by the gNB for the WTRU, for example, as part of a DCI. For example, a DCI received by the WTRU may include an indication of the deadline (e.g., in terms of specific time units, such as X seconds, and / or radio transmission units, such as X time slots). In an example, the WTRU may provide historical information to the gNB regarding the RIS training time spent versus the configured deadline so that the gNB may update the deadline accordingly as needed. There may be triggers at the WTRU and / or signaled from the gNB for providing such RIS training time information. For example, the triggers for the WTRU to transmit the RIS training time information may include: triggers received from the network (e.g., gNB) via signaling (e.g., MAC CE / DCI, etc.) and / or triggers initiated by the WTRU via signaling (UCI, SRS, etc.) based on the configuration received from the gNB (e.g., RRC, MAC CE, DCI, etc.). The WTRU may provide this information as part of the RIS training or configuration process, for example, as described herein with respect to Figure 3 The trigger and / or RIS training report structure may be configured by the gNB.

[0089] The timing associated with the configuration of RIS can be controlled by two nodes (e.g. Figure 2206 and node 208 of the TX node). One or more of the following may be applied. The RIS controller may coordinate the configuration process. For example, the RIS controller may notify both the TX node and the RX node when to send a training signal and / or when the RX node is expected to receive a training signal. Additionally or alternatively, the TX node may schedule the RIS configuration (e.g., based on the training signal transmission interval of the TX node). If the TX node schedules the RIS configuration, the RX node may wait to receive a known sequence and may perform SNR estimation when a training signal is detected (e.g., only when a training signal is detected). For example, when only noise is received, samples may not be stored. Additionally or alternatively, noise samples may be used for noise estimation. In some scenarios, the nodes may, for example, use control plane signaling to agree on timing together. For example, the nodes may use the control plane to communicate directly to agree on timing. Additionally or alternatively, the nodes may communicate via the RIS controller to agree on timing (e.g., if a direct link between the nodes is blocked).

[0090] As described herein, control signaling may be used during RIS configuration. One or more of the following may be applied. When the RX node detects / determines that the measured SNR is less than a threshold SNR, the RX node may communicate with the RIS controller. When the RX node arrives at the network or a cell in the network, an initial connection between the RX node and the RIS controller may be established. For example, the presence of the RIS in the cell may be announced via a data field added in the control plane signaling sent by the network. When the RIS controller sends a beacon signal to announce its presence, an initial connection between the RX node and the RIS controller may be established in addition or alternatively. When the RX node sends a request signal (e.g., to find an available RIS), an initial connection between the RX node and the RIS controller may be established. The selection between different options and implementation details depends on the network in which the RIS is deployed. During the configuration of the RIS, the RX node may measure the received SNR and report the measurement result (e.g., or a performance indicator calculated based on the measurement) to the RIS controller. The signaling indicating the measured SNR may not require a high link capacity, for example, because the information from the RX node includes (e.g., only includes) the measurement result or the performance indicator, which may be a single digit. For example, depending on the implementation of the RIS auxiliary link and / or to minimize the time used to configure the RIS, the latency requirement may be low.

[0091] The control signaling used to configure the RIS may be implementation specific and / or may vary for different deployment scenarios.The techniques described herein are examples, and any other suitable techniques may additionally or alternatively be used.

[0092] One or more techniques for providing expansion to multi-antenna nodes may be provided. WTRUs and network nodes (e.g., base stations (BS) or access points (APs)) in a wireless system may be equipped with antenna arrays that include one or more (e.g., multiple) antenna elements. The RIS configuration techniques described herein may also be used with TX nodes and RX nodes that include multiple antenna elements. One or more of the following may apply.

[0093] If the TX node is equipped with an antenna array, an orthogonal training sequence can be sent from each antenna. For example, each training sequence can be sent in certain directions based on the radiation pattern of the array element (e.g., based only on the radiation pattern of the array element). For example, if the array element is a dipole element, each training sequence can be sent omnidirectionally. In some scenarios (e.g., in 5G NR), the SRS sent from different antenna ports can be orthogonal to each other. For example, if the RIS is located in the far field of the array of the TX node, the plane wave can reach the RIS from a similar (e.g., the same) direction (e.g., due to the orthogonal sequence sent) and / or can be reflected in a similar (e.g., the same) direction. The RX node can detect the orthogonal sequence and measure the associated SNR of the received signal. If the RX node is equipped with an antenna array, the SNR can be calculated at each transmitter chain connected to the array element, which can result in a diversity gain for the SNR measurement.

[0094] After you have determined the appropriate RIS configuration (for example, using the Figure 3

[00136] In some embodiments, the RX node may estimate the channel. The WTRU may notify the RIS controller of the correct RIS configuration and data transmission may begin. The RX node may report channel state information (CSI) to the TX node. The TX node may perform pre-decoding. The RX node may perform combining. The pre-decoding performed at the TX node and the combining performed at the receiver node may be calculated using already existing techniques (e.g., as in a conventional multi-antenna system). For example, the associated codebook may be redesigned to take advantage of the performance improvement provided by the RIS. However, since the pre-decoding at the TX node may be performed after the RIS configuration, the techniques described herein are agnostic to any associated codebook redesign.

[0095] In addition to SNR, other quality indicators may be utilized additionally or alternatively in the RIS configuration. One or more of the following may apply. In a wireless system, the WTRU may use one or more (e.g., several) performance indicators to evaluate link quality. For example, in certain implementations (e.g., 5G NR), the performance indicators may include a channel quality indicator (CQI), a rank indicator (RI), a pre-decoder matrix indicator (PMI), and / or a reference signal received power (RSRP). The CQI value may include a number between 0 and 15 and may be used to select a modulation and coding scheme from a table defined in the 5G NR specification. The RI may indicate the number of transmission layers that the WTRU determines the channel can support. The PMI indicates the pre-decoder matrix applicable to the transmission (e.g., when the RI is known). The RSRP for layer 1 reporting may be applicable to beam management and / or may be referred to as L1-RSRP. In some implementations (e.g., IEEE 802.11 networks), parameters for link quality assessment may include a received signal strength indicator (RSSI), a signal to interference plus noise ratio (SINR), a carrier to noise ratio (CNR, e.g., a measure of received carrier strength relative to received noise strength), a packet delivery ratio (PDR), and / or a bit error rate (BER). For example, the techniques described herein may be supported by one or more of: L1-RSRP, SINR, and / or RSSI. For example, if it is determined that the SNR is suitable for transmission and the rank of the channel does not support multi-layer transmission, the RI indicator may be utilized during RIS configuration. In such examples, the configuration of the RIS configuration may increase channel capacity. CQI and / or PMI may be used in addition or alternatively in the RIS configuration.

[0096] Some other wireless systems may use different channel quality indicators, and the implementation of each of the different channel quality indicators may vary, for example, depending on specific requirements and resources. However, regardless of the channel quality indicator used, the techniques associated with RIS configuration described herein may be employed.

[0097] Figure 4 Examples associated with simulations associated with the techniques described herein (eg, for outdoor use cases) are illustrated. Figure 4For the illustrated example, one or more of the following may apply. The distances (e.g., horizontal distances) between the WTRU and the RIS and between the RIS and the BS may be 5m and 180m, respectively. The WTRU antenna, BS antenna, and RIS heights may be 1.5m, 5m, and 10m, respectively. The transmit power may be 20dBm, the signal bandwidth may be assumed to be 20MHz, and the noise figure of the receiver may be 5dB. The path loss is calculated using the defined urban micro street canyon model. Both the WTRU and the BS may be equipped with a single antenna. The RIS may be modeled as a 64-element uniform linear array with λ / 2 element spacing (e.g., where λ = wavelength of the signal). The antennas and RIS elements may be assumed to be isotropic radiators. The codebook in the search may include one or more rows of a discrete Fourier transform (DFT) matrix. Reference Figure 4 In the illustrated case of SP=1 402, the codebook size may be 64. Figure 4 In the illustrated case of SP=2 404, the codebook size may be 128. The target SNR value in both cases may be 10 dB. In the case of SP=1 402, the failure rate may be 0.01, while in the case of SP=2 404, the failure rate may be reduced to 0. In the case of SP=1 402 and SP=2 404, the average number of iterations in the search may include 33 and 63, respectively.

[0098] Figure 5 Examples associated with simulations associated with the techniques described herein (e.g., for indoor use cases) are illustrated. One or more of the following may apply. The distances between the WTRU and RIS and between the RIS and BS may include 7.5m and 15m, respectively. The WTRU antenna, BS antenna, and RIS heights may be 1.5m, 2.5m, and 2m, respectively. The path loss may be calculated using an indoor office model. The RIS size may be 64, and both the WTRU and BS may be single antenna devices. Reference Figure 5 For the illustrated SP=1 502 case, the failure rate may be 0.03. The failure rate for the SP=2 case may be 0. The average number of iterations performed during the search for the SP=1 502 and SP=2 504 cases may be 33 and 63, respectively.

[0099] like Figure 4 and Figure 5 As shown, the failure rate and / or search time may depend on the size of the codebook. For example, an increase in the codebook size may be associated with a decrease in the failure rate and an increase in the search time. However, the techniques described herein may be used with various (e.g., any) codebook designs. In addition, in combination with Figure 4 and Figure 5 The DTF matrices described by the illustrated examples are exemplary and are used to illustrate the operation and performance of the RIS configuration.

[0100] The RIS configuration techniques described herein may be applied to various networks, including but not limited to 5G NR. For example, the RIS discovery process may be performed, for example, as part of an initial access process. One or more of the following may apply. A network node such as a base station (e.g., a gNB) may periodically send a synchronization signal (SS) block. The periodicity of the SS blocks sent may vary, for example, between 10ms and 160ms. For example, the SS block may include a primary synchronization signal (PSS), a secondary synchronization signal (SSS), a broadcast signal, and / or an indication of a physical broadcast channel (PBCH). In some cases, the broadcast signal may carry a portion of system information for the WTRU to access the network or synchronize with the network.

[0101] The RIS controller may be equipped with a transceiver (e.g., such as Figure 1B 120 as illustrated). For example, the RIS controller may use the transceiver (e.g., via a beacon signal) to announce specific information associated with the RIS (e.g., available RIS resources). The gNB may configure the WTRU to assist the WTRU in RIS discovery and discovery of available RIS resources, for example, as part of an initial access procedure. For example, the WTRU may be configured to receive and / or decode information announced by the RIS in a cell. In some scenarios, the RIS beacon signal transmitted by the RIS controller may be synchronized with other control signaling from the gNB. A WTRU located within the coverage area of ​​the RIS may receive this information announced by the RIS. For example, the RIS controller may include in its advertisement one or more of: the presence of a RIS unit (e.g., or the number of RIS units if more than one unit is controlled by the same controller); properties of the RIS unit (e.g., size, number of elements, array gain, etc.); information associated with the RIS type and / or RIS capabilities (e.g., active / passive, reflective / transmissive, etc.); the location of the RIS unit; the type of information expected from the WTRU (e.g., RIS configuration and / or preferred phase shift matrix); one or more performance indicators (e.g., SNR, CQI, RI, PMI, RSRP); information that can be used for RIS element configuration; and / or a link quality indicator (e.g., for the RIS controller to calculate the RIS configuration based on the RIS implementation).

[0102] Based on the information announced by the RIS controller, the WTRU may determine to use one or more RIS resources, for example, by initiating a RIS configuration procedure. For example, if the WTRU wants to use RIS resources, the WTRU may transmit a RIS resource request to the RIS controller. Additionally or alternatively, the WTRU may transmit a RIS resource request to a network node (e.g., a gNB), which may then forward the RIS resource request to the RIS (e.g., a RIS controller). During RIS configuration, the WTRU may communicate with the RIS controller.

[0103] The WTRU may define the RIS configuration based on, for example, a signal quality indicator in the CSI. Information included in a RIS controller transmission (e.g., information notified by the RIS controller) may indicate the structure and properties of the RIS unit. For example, the structure and properties of the RIS unit may include a number of RIS elements, phase and amplitude ranges of the RIS elements, and / or operating modes (e.g., reflection, refraction, absorption, etc.). The information may be included in the RIS controller transmission and / or may further include detailed information about the unit cells of the RIS (e.g., the number of unit cells); which components are used to control the operation of the unit cells (e.g., PIN diodes, transistors); the number of bits in the control word used to control a single unit cell in the RIS; and / or the phase and amplitude response of the unit cell caused by the control word. Additionally or alternatively, the WTRU may transmit the CSI to the RIS controller, and the RIS controller may define the details for the RIS configuration. In this case, the WTRU may not know the details of the manufacturing and component technologies used to implement the RIS unit.

[0104] As described herein, beacon and control signaling between the WTRU and the RIS controller may additionally or alternatively be implemented using narrowband Internet of Things (NB-IoT) transmissions (e.g., using 5G in-band transmissions or guard bands between 5G carriers). Additionally or alternatively, different radio links for WTRU to RIS control signaling may be defined. The gNB and / or the WTRU may configure one or more new dedicated control links for the RIS. The new dedicated control links may be lower in complexity than, for example, the PDCCH / PUCCH (physical downlink / uplink control channels) used for WTRU-gNB communications. The one or more new dedicated control links may be referred to as physical RIS control channels (PRCCs). Different radio links may be implemented using radio technologies other than the radio technology used for data transmission between the WTRU and the gNB. For example, the RIS may be used for the link between the WTRU and the gNB, but the control signaling between the WTRU and the RIS controller may be accomplished using one or more wireless local area network transmissions.

[0105]

[00136] In certain scenarios, RIS discovery may be performed without a transmission from a RIS controller. For example, a network node (e.g., a gNB) may transmit (e.g., periodically) an SS block. The periodicity of the SS block may vary, for example, between 10 ms and 160 ms. The SS block may include a primary synchronization signal (PSS), a secondary synchronization signal (SSS), and / or a PBCH. For example, the PBCH may include a master information block (MIB) that includes information for the WTRU to obtain system information about the network (e.g., scheduling information for receiving system information block 1 (SIB1)).

[0106] During the initial access procedure, the WTRU may search for available cells and wait to receive the associated SS. After the WTRU detects the SS, the WTRU may synchronize with the network and obtain system information associated with the network. If the RIS is present in the cell, information indicating the presence of the RIS may be added to the data sent in the PBCH. The WTRU may continue to monitor the SS block transmission. If the RIS has not been reserved for the link between the gNB and the WTRU, the network may change the RIS configuration. For example, the network may synchronize the configuration of the RIS with the transmission of the SS blocks. Additionally or alternatively, information associated with the periodicity of the RIS configuration may be included in the PBCH content.

[0107] If RIS exists in the cell, information indicating the presence of RIS may be added to the data sent in PBCH. For example, one or more information bits may be added to the MIB, which may be used to indicate the presence (e.g., or absence) of RIS in the cell. In an example, the MIB may include one or more of the following fields: cellBarred, dmrs-TypeA-position, intraFreqReselection, pdcch-ConfingSIB1, ssb-SubcarrierOffset, subCarrierSpacingCommon, systemFrameNumber, and / or an indication of the presence of RIS (e.g., RIS presence field).

[0108] In an example, RIS information (e.g., RIS presence field) may be included in SIB1 that is sent (e.g., periodically) in a physical downlink shared channel (PDSCH). The WTRU may continue to monitor the SS block transmission. For example, if the RIS has not been reserved for any link between the network node and the WTRU, the network may change the RIS configuration, for example, to synchronize with the SS block transmission. The network may change the RIS configuration by, for example, explicit signaling from the gNB to the RIS controller. For example, the signaling between the gNB and the RIS controller may be sent via a backhaul link, a wired link, an in-band link, an out-of-band link, etc. Information about the periodicity of the RIS configuration may also be added to the PBCH (e.g., by extending the MIB or SIB1).

[0109] If the RIS discovery procedure is performed as part of the initial access procedure, one or more of the following may apply. A RIS and / or RIS controller may be deployed. The RIS information field may be included in the PBCH, (MIB) and / or SIB1CH. For example, the RIS information field may indicate the presence of a RIS and / or timing information associated with the RIS configuration. A control link between the RIS controller and the WTRU may be established.

[0110] For example, configuration of the RIS may be performed at the start of data transmission and / or during initial access.

[0111] A link (e.g., a direct link) may be established between the WTRU and the gNB, or a direct link may not exist. However, in some cases, the measured SNR associated with the link may be below a threshold SNR. One or more of the following may apply. The WTRU may initiate data transmission. The WTRU may measure the power of the received SS blocks and calculate the associated SNR. If the SNR is below the threshold SNR, the WTRU may send a request to reserve the RIS to the RIS controller. If the RIS is available, the WTRU may be granted control of the RIS.

[0112] In some scenarios, the WTRU may continue to monitor the SNR measured from the SS block, for example, while updating the RIS configuration. When the SNR reaches or exceeds the SNR threshold, the WTRU may reserve the RIS and notify the RIS controller to use the corresponding RIS configuration. The WTRU may initiate data transmission with the gNB.

[0113] In some scenarios, a link between the WTRU and the gNB may be established even when the measured SNR level is below an SNR threshold. The WTRU may reserve the RIS. The gNB may, for example, send the CSI-RS with a minimum periodicity (e.g., 5 ms). When the SNR reaches or exceeds the SNR threshold, the WTRU may instruct the RIS controller to use the corresponding RIS configuration and may initiate data transmission. If the threshold SNR is not achieved after a predetermined time, the RIS may be released.

[0114] As described herein, the WTRU may transmit configuration instructions to the RIS controller. In some scenarios, the WTRU may transmit control instructions to the gNB, which in turn may relay the control instructions to the RIS controller. Additionally or alternatively, the WTRU may communicate directly with the RIS controller.

[0115] If the WTRU transmits a control instruction to the gNB, the RIS control information may be transmitted to the gNB and may be included in the uplink control information (UCI) included in the physical uplink control channel (PUCCH) transmission. The UCI may additionally or alternatively be transmitted in a physical uplink shared channel (PUSCH) transmission. Depending on the RIS implementation and / or how the RIS units are integrated into the network, a control messaging arrangement may be used to transmit the RIS control information (RCI). If the RIS is deployed by a network operator, the connection between the RIS controller and the gNB may, for example, include extending a given interface (e.g., an F1 interface for interconnecting a base station-centralized unit (gNB-CU) and a base station-distributed unit (gNB-DU) to include an interface between the gNB and the RIS controller).

[0116] If the WTRU communicates directly with the RIS controller, the RIS controller may include a transceiver. For example, if the link between the gNB and the WTRU is blocked, the WTRU may communicate with the RIS controller to perform RIS configuration.

[0117] As described herein, UCI may be used to transmit channel state information (CSI), hybrid automatic repeat request (HARQ) acknowledgments, and scheduling requests to the network. If a connection between the gNB and the WTRU has been established, the UCI may also be used to report CSI from the WTRU to the gNB for RIS control and / or RIS configuration. However, if the direct link between the WTRU and the gNB is blocked, the WTRU may communicate with a RIS controller (e.g., to receive transmissions from the network before the WTRU begins transmitting to the network). The RIS configuration (e.g., a selected RIS configuration and / or a preferred RIS configuration) may be determined prior to the transmission of user plane data between the WTRU and the gNB. For example, the RIS configuration may be determined by measuring the power of a synchronization signal sent by the gNB and reflected by the RIS to the WTRU. Based on the measured power of the synchronization signals (e.g., the WTRU-gNB channel and the WTRU-RIS channel), the WTRU may determine the RIS configuration and send an indication of the determined RIS configuration to the RIS controller. The WTRU may report received signal quality (e.g., received power and / or SNR) or instructions for RIS configuration to the RIS controller, for example, using a radio link between the WTRU and the RIS controller (e.g., UCI for the RIS controller-WTRU link). In an example, the WTRU may not transmit the determined RIS configuration to the RIS controller. For example, the WTRU may send an indication and / or information for the RIS controller to update its configuration (e.g., because performance has degraded below a certain threshold). The information may also include some measurement information that the RIS controller may use to select an appropriate RIS configuration.

[0118] The size of the RIS and / or associated technology may vary. If the WTRU receives information about RIS elements deployed in a cell, the WTRU may control the RIS, for example, by defining the RIS configuration at the circuit level (e.g., directly controlling the reflection of a single RIS element). For example, the information about the RIS elements deployed in the cell may include, but is not limited to, a predetermined set of beams for the RIS (e.g., in which case the WTRU may send an index indicating the selected beam). The information transmitted by the RIS controller may also include detailed information about how the various RIS elements operate, which the WTRU may use to determine the expected phase response or phase and amplitude response of the RIS element. The detailed information may include information such as the range of phases and amplitudes that the RIS element may support (e.g., for phase, there may be a set of discrete values ​​to select from, rather than a continuous phase capability). The RIS controller may transmit to the WTRU one or more of the following: a preferred set of beam IDs / indexes from a predefined set; a desired phase response (e.g., based on the WTRU processing of the received beam); and / or a desired phase and amplitude response (e.g., based on the WTRU processing of the received beam).

[0119] If a radio link between the RIS controller and the WTRU exists, the RIS controller may provide this information to the WTRU. Additionally or alternatively, the WTRU may report the CSI to the RIS controller, and the RIS controller may determine the RIS configuration (e.g., based on the CSI). For example, if the details associated with the RIS implementation may not be visible to the WTRU or the network, the WTRU may report the CSI to the RIS controller.

[0120] As described herein, DCI may be used for scheduling (e.g., including sidelink scheduling) and transmitting transmit power control (TPC) messages to the WTRU. When the RIS controller communicates with the WTRU over a radio link (e.g., in the case of WTRU control), the RIS controller may transmit information about RIS attributes and an acknowledgement of a request for RIS resources to the WTRU (e.g., DCI in the RIS controller-WTRU radio link). In addition to the first DCI between the gNB-WTRU, the gNB and / or the WTRU may configure a second DCI between the RIS controller-WTRU to enable the exchange of control information.

[0121] Figure 6 An example associated with RIS configuration signal timing is shown. Figure 6As illustrated, the RIS configuration may be changed, for example, to synchronize with the transmission of the SS block. When the WTRU receives the SS block, the WTRU may synchronize with the network and receive system information from the PBCH. The PBCH may include information about the periodicity of the RIS configuration. After the PBCH is received, the WTRU may determine the network and RIS controller timing. If the WTRU attempts to establish a connection for data transmission, the WTRU may reserve the RIS, for example, by sending a RIS reservation request (RR). The WTRU may inform the RIS controller that it is able to receive signals from a gNB with a corresponding RIS configuration. The RIS controller may send a RIS reservation confirmation (Rack), for example, to verify that the RIS is reserved for the WTRU. The RIS configuration may be initially set to the configuration received from the WTRU. The RIS reservation request may be transmitted as part of one or more uplink physical channels or signals (e.g., physical random access channel (PRACH), PUCCH, PUSCH, SRS) or implicitly transmitted by a specific selection of UL resources (e.g., PRACH, PUCCH, PUSCH, SRS). If the SNR threshold specification is not met, the set RIS configuration may be used as a starting point for RIS configuration (e.g., Figure 3 As illustrated). The WTRU may receive the SNR threshold via pre-configuration of the gNB (e.g., RRC) or dynamic configuration of the gNB (e.g., MAC CE, DCI, etc.). The WTRU may determine and indicate the second threshold (e.g., dynamically) based on its own measurements. During RIS configuration, the WTRU may transmit a feedback (FB) signal to the RIS controller. The FB signal may include a performance indicator for the RIS controller. The RIS controller may use the FB signal to determine the next configuration or to guide instructions for RIS configuration. If the WTRU has not moved away from a location where it can receive SS blocks, the FB signal is used to optimize the RIS configuration. When the threshold SNR value is reached, the RIS configuration may end and data transmission may begin. If the SNR target is not reached after a predetermined time, the RIS may be released. Additionally or alternatively, the RIS may be released after the session between the WTRU and the BS is stopped. In some scenarios, a link (e.g., a direct link) between the WTRU and the gNB may not exist. If a link between the gNB and the WTRU does not exist, the RIS may be configured before the connection can be established. One or more of the following may apply.

[0122] For example, the RIS configuration may be changed to synchronize with the transmission of the SS block. When the WTRU receives the SS block, the WTRU may synchronize with the network and receive system information from the PBCH. The PBCH may include information about the timing and / or periodicity of the RIS configuration. After receiving the PBCH, the WTRU may know the timing associated with the network and the RIS / RIS controller. If the WTRU attempts to establish a connection for data transmission, the WTRU may reserve the RIS and notify the RIS controller that the WTRU is able to receive signals from a gNB with a corresponding RIS configuration. The RIS configuration may be (e.g., initially) set to that configuration. For example, if the measured SNR is less than a threshold SNR, the set RIS configuration may be used as a starting point for the search process, which may speed up the search (e.g., if the WTRU has not moved away from a location where it is able to receive the SS block). When the target SNR is reached, the RIS configuration process may be stopped and the WTRU may start data transmission. If the threshold SNR is not reached after a predetermined time, the RIS may be released.

[0123] Figure 6 An example associated with control signaling for RIS configuration is illustrated. At step 604, the WTRU may receive and detect one or more SSS and / or PBCH transmissions periodically sent by the gNB. The SSS and / or PBCH may be reflected by the RIS or received by the WTRU directly from the gNB. At step 606, the WTRU may perform synchronization with the gNB and / or RIS. The WTRU may also discover the RIS. At step 608, the WTRU may establish a connection with the RIS and measure a performance metric (e.g., SNR). If the performance metric is below a threshold, the WTRU may request RIS service, for example, by transmitting a RIS reservation request. At step 610, the WTRU may receive an indication of the availability of the RIS from the RIS or a RIS controller. The indication may include a RIS reservation acknowledgement (RACK), a RIS reservation negative acknowledgement (RNACK), or any other indication detailing the availability of the RIS for use by the WTRU. At step 612, the WTRU may then receive CSI configuration information (e.g., channel state information reference signal (CSI-RS)) from the gNB. The CSI configuration information may be reflected by the RIS before reaching the WTRU. At step 614, the WTRU may measure the signal quality (e.g., via the SNR) and based on the measurement, may transmit a request for an updated RIS configuration (e.g., a RIS configuration update request) to the RIS or RIS controller in an attempt to increase the SNR. For example, if the measurement result (e.g., the SNR) is below a threshold, the WTRU may transmit a request for an updated RIS configuration (e.g., a RIS configuration update request) to the RIS or RIS controller.

[0124] At step 616, a signal quality measurement (e.g., SNR) threshold is reached and / or a deadline is reached. At step 618, the RIS configuration process may be terminated by the WTRU, gNB, RIS, and / or RIS controller. If the threshold is not reached and the deadline is exceeded, the RIS may be released by the WTRU, gNB, RIS, and / or RIS controller. If the threshold is reached, data transmission may begin. At step 620, the WTRU may receive scheduling information for sending data to or receiving data from the gNB via the RIS. The gNB may send the scheduling information via the PDSCH or PDCCH. At step 622, the WTRU may receive data via the RIS using the PDSCH based on the scheduling information. The WTRU may also transmit data to the gNB via the RIS using the PUSCH.

[0125] In some cases, the WTRU may include a processor configured to receive RIS discovery information (e.g., Figure 1B The illustrated processor 118), the RIS discovery information indicates that a RIS exists for a transmission in the cell (e.g., available, within range). The RIS discovery information may include one or more locations of the RIS in the cell, RIS capabilities (e.g., the capabilities of each of the RIS in the cell), the number of unit cells, etc. The RIS discovery information may be included in a synchronization signal (SS) block (e.g., having a periodicity between 10ms and 160ms). The SS block may include an indication of the PSS, SSS, and / or PBCH. During the initial access procedure, the WTRU may search for available cells and wait to receive associated SS, PSS, SSS, and / or PBCH transmissions (e.g., the PBCH may include RIS discovery information). The WTRU may receive the discovery information in the PBCH.

[0126] The WTRU may perform one or more first measurements of one or more first signals to determine a first measurement value. Any measurement / parameter related to channel quality may be used for RIS control. In some cases, channel quality and / or channel state information (e.g., SNR calculation) may be based on measurement (e.g., reference signal power) or calculation (e.g., based on the location of the RIS in the cell). In some cases, the one or more first signals may include one or more broadcast signals. The one or more first signals may additionally or alternatively include training signals, CSI-RS, SRS, SS, PSS and / or any signal received via PBCH and / or SS. The one or more first measurements may include measuring channel quality and / or channel state information. The one or more first measurements may include one or more quality metric measurements (e.g., SNR, RSRP, signal power, noise level, interference level, signal to interference plus noise ratio (SINR), block error rate (BLER), peak signal to noise ratio (PSNR), geometric signal to noise ratio (GSNR), CQI, ACK, and / or NACK). The WTRU may be configured to achieve (e.g., obtain, maintain, etc.) a predetermined signal and / or channel quality level, which may be measured using a quality metric measurement such as SNR. The one or more first measurements may also include the WTRU performing channel estimation, spectrum and / or energy efficiency optimization techniques.

[0127] The measurement value may include one or more measurements from any of the measurement techniques disclosed herein. One or more of the following may apply. The WTRU may select a measurement value derived from various measurement value types, including a first measurement, a second measurement, a third measurement, an intermediate measurement, a last measurement, a highest measurement, a lowest measurement, a mean measurement, a median measurement, a mode measurement, a logarithmic mean, a geometric mean, a measurement occurring during a specified time period, and / or an nth measurement (e.g., an unspecified measurement number in a measurement series).

[0128] The WTRU may determine that the first measurement value is less than a threshold value. The threshold value may be defined based on a target set by the application or service used (e.g., a threshold value defined from an upper layer, a middle layer, a lower layer, an RRC, PDCP, RLC, a MAC and / or a PHY layer), a previous measurement value measured by the WTRU, a link quality target (e.g., a data rate), the WTRU (e.g., an operational target), and / or any element in the network. In some cases, the threshold value may be stored in the WTRU (e.g., in a table, a database, a memory, a random access memory (RAM), a processor, and / or a cache). In various cases, the WTRU may interpret "less than" as "less than or equal to". The comparison between the threshold value and the first measurement value may be performed in various ways, for example, by using a digital comparator, an analog comparator, and / or an amplitude comparator in the WTRU and / or the WTRU. The first measurement value being less than the threshold value may indicate that the signal quality is not good enough or not reliable enough to start data transmission.

[0129] The WTRU may transmit a reservation request to the RIS based on the first measurement value being less than (or less than or equal to) a threshold. Because the signal quality and / or power from the gNB is not high enough, the WTRU may seek the services of the RIS to reflect more signals to increase the measurement value of the signal. The WTRU may transmit a reservation request to the RIS in the form of a signal.

[0130] The WTRU may perform one or more second measurements of one or more second signals received via the RIS to determine second measurement values. The WTRU may receive a RACK and / or an RNACK from the RIS. The RACK may indicate to the WTRU that the RIS is available for use by the WTRU, while the RNACK may indicate that the RIS is not available for use by the WTRU. In some cases, a single RIS may be used by two, three, or more WTRUs simultaneously. In some cases, the RIS reservation request signal may not reach the RIS with a good enough quality for the RIS to recognize that the signal is a RIS reservation request. In such cases, the RIS may transmit a request to the WTRU to retransmit the signal. In some cases, the WTRU may not receive a response from the RIS. In such cases, the WTRU may retransmit the RIS reservation request or may transmit the reservation request to another RIS. When the RIS transmits the RNACK to the WTRU, the RNACK may include a forwarding recommendation with one or more RISs in the RIS network that the WTRU may alternatively use. After the WTRU receives the RACK, the WTRU may receive one or more second signals (e.g., CSI, CSI-RS, and / or tracking reference signals) transmitted from the gNB and reflected by the RIS. The one or more second measurements may be performed using any of the measurement techniques possible for the one or more first measurements (e.g., the same as one or more previous measurement techniques). In some cases, a different measurement technique may be used for the second measurement than for the first measurement. The second measurement may be selected using any of the criteria possible for the first measurement (e.g., the same as one or more previous measurement values). In some cases, a different measurement type may be used for the second measurement than for the first measurement.

[0131] The WTRU may determine that the second measurement value is less than the threshold value. Similar comparison techniques described in the comparison between the first measurement value and the threshold value may be used here (e.g., the same as one or more previous comparison techniques). In some cases, a different comparison technique may be used for this comparison than one or more previous comparisons).

[0132] The WTRU may transmit a RIS configuration update request to the RIS based on the second measurement value being less than the threshold. The RIS configuration update request may include a signal that, when received by the RIS, instructs the RIS to modify, change, and / or alter parameters associated with the RIS. These changes may be used to increase the measurement value of future signals.

[0133] After sending the RIS configuration update request, the WTRU may be further configured to perform one or more third measurements of one or more third signals received via the RIS to determine a third measurement value. The one or more third measurements may be performed using any of the measurement techniques possible for the one or more first measurements and the second measurements (e.g., the same as one or more previous measurement techniques). In some cases, a different measurement technique may be used for the third measurement than the first measurement and / or the second measurement. The second measurement value may be selected using any of the criteria possible for the first measurement value (e.g., the same as one or more previous measurement values). In some cases, a different measurement value type may be used for the third measurement value than the first measurement value and / or the second measurement value.

[0134] The WTRU may determine that the third measurement value is greater than (or greater than or equal to) a threshold value. Similar comparison techniques described in the comparison between the first measurement value and the threshold value and the second measurement value and the threshold value may be used here (e.g., the same as one or more previous comparison techniques). In some cases, a different comparison technique may be used for this comparison than one or more previous comparisons).

[0135] After determining that the third measurement value is greater than the threshold, the WTRU may perform data transmission via the RIS. The data may include any analog signal and / or digital signal. The data may be sent by the gNB to the WTRU via the RIS and / or by the WTRU to the gNB via the RIS. The WTRU may periodically perform measurements of the data signal quality. If the quality begins to degrade (for example, because the WTRU has moved location and the signal quality is at or below another threshold), the WTRU may transmit another RIS configuration update request to have the RIS change one or more of its parameters. If the signal is still at or below the threshold after the deadline, the WTRU may issue a reservation request to another available RIS.

[0136] The WTRU may be further configured to receive the one or more first signals directly from the base station (e.g., using interference, assistance, and / or reflections from the RIS). The WTRU's direct reception of the one or more first signals may include suppressing the one or more first signals reflected by the RIS. "Directly" may include a situation where the WTRU has not established a connection with the RIS and the RIS unintentionally (e.g., accidentally) reflects the one or more first signals.

[0137] In other cases, the RIS discovery information may be received via the RIS. In these cases, the RIS reflects, assists, and / or interferes with one or more signals carrying the RIS discovery information (e.g., before a connection has been established between the WTRU and the RIS). In some cases, the RIS may reflect the RIS discovery information signal based on its prior configuration information with the WTRU or another WTRU. In some cases, the discovery information may be included in the one or more first signals or may be transmitted as part of another signal.

[0138] The one or more first signals, second signals, and third signals may be transmitted by the gNB and reflected by the RIS to the WTRU. The one or more first signals, second signals, and third signals may include any combination of signal types disclosed herein. "Reflection" may include any reflection that modifies signal power, quality, direction, and / or properties. In some embodiments, the one or more first signals, second signals, and / or third signals may be transmitted by the gNB to the WTRU (e.g., reflected by the WTRU or not reflected by the WTRU) via a physical downlink shared channel (PDSCH).

[0139] The WTRU may be further configured to transmit the reservation request and the RIS configuration update request as a first type of uplink control information (UCI). The first type of UCI may have unique attributes for signals transmitted from the WTRU and received by the RIS.

[0140] The WTRU may be further configured to receive an indication of the availability of the RIS as a first type of downlink control information (DCI). The first type of DCI may have unique attributes for signals transmitted from the RIS and received by the WTRU.

[0141] The attributes of the first type of UCI and DCI (e.g., UCI / DCI sent between the WTRU and the RIS) may be different from the attributes of the second type of UCI and DCI (e.g., UCI / DCI sent between the WTRU and the gNB). For example, the attributes of the first type of UCI and DCI may include one or more of the following: different bit structure formats (e.g., more or fewer bits), more or fewer fields within certain formats, different arrangements of fields, different number of bits for a given field, different methods of determining the number of bits in a field, different bit sequences, different codebook types used, different number of CSI ports, different methods for determining the value for a given field (e.g., frequency hopping flag, modulation and coding scheme, redundancy version, HARQ process number, first downlink assignment index, SRS request, rank indicator, layer indicator, wideband CQI, sub-band differential CQI, etc.), different usage, different usage for the same format, and / or different transmission procedures. These properties of the first type of UCI and DCI (eg, UCI / DCI sent between the WTRU and the RIS) may enable more efficient communication between the WTRU and the RIS.

[0142] The WTRU may be further configured to receive the broadcast signal, one or more of the first signal, the second signal, and the third signal as a second type of downlink control information (DCI), and scheduling information via a physical downlink control channel (PDCCH) as a second type of downlink control information (DCI). The second type of DCI may have unique attributes for signals transmitted from the gNB and received by the WTRU.

[0143] The WTRU may be further configured to transmit a hybrid automatic repeat request acknowledgement (HARQ-ACK), a hybrid automatic repeat request negative acknowledgement (HARQ-NACK), channel state information (CSI), or a scheduling request (SR) for data transmission to the base station via a physical uplink control channel (PUCCH) or a physical uplink shared channel (PUSCH) as a second type of uplink control information (UCI). The second type of UCI may have unique attributes for a signal transmitted from the WTRU and received by the gNB. The HARQ-ACK may indicate that the WTRU has successfully decoded the received transmission. The HARQ-NACK may indicate that the WTRU failed to successfully decode the received transmission. The success and / or failure of the transmission may be determined based at least in part on error detection using one or more cyclic redundancy checks (CRCs). The CSI may include any known channel properties of any communication link (WTRU-gNB, WTRU-RIS, RIS-gNB, etc.) disclosed herein. The CSI may describe how the signal propagates from the WTRU to the gNB and may represent, for example, the combined effects of scattering, fading, and power attenuation with distance (e.g., channel estimation). The CSI may make it possible to adapt the transmission to the current channel conditions, which is useful for achieving reliable communications with high data rates. The CSI may include the type of fading distribution, average channel gain, line-of-sight component, and spatial correlation. The scheduling request may include a request from the WTRU to the gNB for uplink shared (UL-SCH) resources for transmission.

[0144] In some cases, at least one of the one or more first, second, or third signals may include a synchronization signal block (SSB) or a channel state information reference signal (CSI-RS). The SSB and CSI-RS may include any of the SSB and CSI-RS attributes disclosed herein.

[0145] The WTRU may be further configured to receive a RIS reservation acknowledgement (RACK) or a RIS reservation negative acknowledgement (RNCK) as a first type of downlink control information (DCI) in response to the reservation request. The RACK and RNACK may be used as an indication of the availability of the RIS. The RACK may indicate that the RIS is available for connection with the WTRU and / or that the received RIS successfully decoded the RIS reservation request. The RNACK may indicate that the RIS is not available for connection with the WTRU and / or that the received RIS failed to successfully decode the RIS reservation request.

[0146] In some cases, at least one of the first measurement, the second measurement, or the third measurement is a signal-to-noise ratio (SNR). The SNR may include a ratio of signal power to noise power.

[0147] The WTRU may be further configured to release the RIS if the first measurement value, the second measurement value, and the third measurement value are less than (or equal to) a threshold for a certain period of time. The period of time may include a plurality of time slots (e.g., X time slots). After the WTRU repeatedly attempts to establish a successful configuration with the RIS for data transmission and reception with the gNB, the RIS may be released after a given amount of time. "Release" may mean temporarily severing the communication between the WTRU and the RIS, lowering the priority order of the WTRU in the connection / configuration queue at the RIS, setting a deadline before the WTRU may attempt to communicate with the RIS again, etc.

[0148] Configuration of the RIS may be performed during data transmission. For example, in certain scenarios, the link between the WTRU and a network node (e.g., a gNB) may be active, and the WTRU may move to an area where the measured SNR is less than an SNR threshold. One or more of the following may apply. A drop in the measured SNR may be detected at both the WTRU and the gNB (e.g., because the channel is reciprocal). The WTRU and / or the gNB may request the use of the RIS. If use of the RIS is granted for the link, the RIS configuration may be changed, for example, to synchronize with the reference signal transmitted. For example, as described herein, the configuration of the RIS may be changed (e.g., modified / updated) based on measurements at the WTRU, and the associated SNR may be measured using the CSI-RS. Additionally or alternatively, the configuration of the RIS may be performed based on measurements made by a network node (e.g., a gNB). The measurement results may be reported to the gNB using uplink control information (UCI). The gNB may then forward the information to the RIS controller. If the RIS controller is equipped with a transceiver, it may also receive SNR reports directly from the WTRU by receiving UCI. If the RIS configuration is performed based on the SNR at the gNB, the gNB may use the SRS to perform SNR measurements. In some scenarios, the SNR may be measured at one end of the link (e.g., only one end). For example, if the SNR is measured only at one end of the link, the device measuring the SNR (e.g., the WTRU or gNB) may not report the measured SNR value to the RIS controller, which may minimize control signaling between the WTRU and the RIS controller. The device measuring the SNR may notify the RIS controller when the SNR has reached the SNR threshold.

[0149] In a TDD link, SNR measurements can be performed at both ends of the link, which can speed up the configuration process.

[0150] Although the examples described herein list SNR as a quality indicator for performing RIS configuration, other quality indicators (eg, RI, layer indicator (LI), etc.) may additionally or alternatively be used.

[0151] The RIS configuration techniques described herein do not limit the control messaging that may occur between the gNB, WTRU, and / or controller. For example, one or more of the following may apply. The control plane for the RIS configuration may be implemented using a side link (e.g., a 5G NR side link connection). The control plane for the RIS configuration may be implemented via existing network protocols such as LTE and / or non-standalone 5G. The RIS controller may be part of an existing system architecture (e.g., a 5G NR architecture). The RIS controller may include an open RAN component. The RIS controller may communicate using a non-cellular connection (e.g., Wi-Fi, Bluetooth).

[0152] The deployment of RIS units within an already existing network (e.g., a 5G NR network) may create a need to supplement the protocol stack of the already existing network.

[0153] For example, Figure 7 An example protocol stack of a system 700 including a RIS 702 is illustrated. One or more of the following may apply. The RLC layer 710 may be responsible for radio resource control in the network. The RLC layer 710 may be updated to incorporate RIS control 704 (e.g., because the RIS 702 may be part of the radio resources). In some cases, the network may control the RIS with respect to one or more of: transfer of upper layer protocol data units (PDUs); error correction through ARQ; concatenation, segmentation, and reassembly of RLC service data units (SDUs); resegmentation of RLC data PDUs; reordering of RLC data PDUs; duplicate detection; RLC SDU discard; RLC re-establishment; and / or protocol error detection and recovery. For example, the RIS may transfer upper layer protocol data units (PDUs) in one of a plurality of modes, including: acknowledged mode (AM), unacknowledged mode (UM), and / or transparent mode (TM); changes may be made to the MAC layer 712 (e.g., because the gNB may also serve other nodes that do not employ RIS). For example, in some cases, the network may control RIS with respect to frame delimitation and identification, control of access to the physical transmission medium, and / or transparent data transfer of low latency communication (LLC) PDUs. SNR measurements for RIS control may be incorporated into the PHY layer 714. For example, in some cases, the network may control RIS with respect to communications in PDSCH, PDCCH, PBCH, PRACH, PUSCH, and / or PUCCH (e.g., as Figure 5 and Figure 6). The RRC protocol 706 and PDCP 708 in the network layer (located in the radio protocol stack in the UMTS / LTE / 5G air interface above the RLC layer) can be modified to incorporate RIS control and communication. Additional interfaces 716 can be defined, such as interfaces between the existing network, RIS controller and WTRU, and / or interfaces between the RIS controller and RIS.

Claims

1. A wireless transmit / receive unit (WTRU), comprising: A processor, the processor being configured to: receiving a reconfigurable intelligent surface (RIS) discovery message indicating the presence of a RIS; performing one or more first measurements of the one or more first signals to determine first measurement values; determining that the first measurement value is less than a threshold; transmitting a reservation request to the RIS based on the first measurement being less than the threshold; performing one or more second measurements of one or more second signals received via the RIS to determine second measurement values; determining that the second measurement value is less than the threshold; as well as A RIS configuration update request is transmitted to the RIS based on the second measurement value being less than the threshold.

2. The WTRU of claim 1 , wherein the processor is further configured to: performing one or more third measurements of one or more third signals received via the RIS to determine third measurement values; determining that the third measurement value is greater than the threshold; and After determining that the third measurement value is greater than the threshold, data transmission is performed via the RIS.

3. The WTRU of claim 1 , wherein the RIS discovery information is received in a physical broadcast channel (PBCH) transmission.

4. The WTRU of claim 1 , wherein the one or more first signals are received from a base station.

5. The WTRU of claim 1 , wherein the RIS discovery information is received via the RIS.

6. The WTRU of claim 1 , wherein the processor is further configured to transmit the reservation request and the RIS configuration update request as a first type of uplink control information (UCI).

7. The WTRU of claim 1 , wherein the processor is further configured to receive an indication of availability associated with the RIS.

8. The WTRU of claim 1, wherein the processor is further configured to receive a broadcast signal as a second type of downlink control information (DCI).

9. The WTRU of claim 1 , wherein the processor is further configured to receive scheduling information as a second type of downlink control information (DCI) via a physical downlink control channel (PDCCH).

10. A method implemented by a wireless transmit / receive unit (WTRU), the method comprising: receiving a reconfigurable intelligent surface (RIS) discovery information indicating that a RIS exists for transmission in a cell; performing one or more first measurements of the one or more first signals to determine first measurement values; determining that the first measurement value is less than a threshold; transmitting a reservation request to the RIS based on the first measurement being less than the threshold; performing one or more second measurements of one or more second signals received via the RIS to determine second measurement values; determining that the second measurement value is less than the threshold; as well as A RIS configuration update request is transmitted to the RIS based on the second measurement value being less than the threshold.

11. The method according to claim 10, further comprising: performing one or more third measurements of one or more third signals received via the RIS to determine third measurement values; determining that the third measurement value is greater than the threshold; as well as After determining that the third measurement value is greater than the threshold, data transmission is performed via the RIS.

12. The method of claim 10, wherein the RIS discovery information is received in a physical broadcast channel (PBCH) transmission.

13. The method of claim 10, wherein the one or more first signals are received from a base station. The method of claim 10 , wherein the RIS discovery information is received via the RIS.

15. The method of claim 10, further comprising transmitting the reservation request and the RIS configuration update request as a first type of uplink control information (UCI).

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