Reconfigurable Intelligent Surfaces (RIS) Assisted Initial Access

Abstract

The WTRU may detect a reflected SSB transmission from the RIS. The reflected SSB is associated with an index. The WTRU may determine a source device of the reflected SSB transmission based on the index. For example, the WTRU may determine that the reflected SSB transmission was reflected by the RIS based on the index associated with the RIS. The WTRU may perform a random access procedure with the network device via the RIS based on the index. The SSB transmission may be associated with an SSB burst transmission including multiple SSB transmissions, each of which may be associated with an index. The multiple SSB transmissions may include SSB transmissions that were reflected by the RIS and / or SSB transmissions that were not reflected by the RIS. The spatial state of the RIS may remain constant and / or may change during the SSB burst transmission.

Description

[Technical field]

[0001] (CROSS REFERENCE TO RELATED APPLICATIONS) This application claims priority to U.S. Provisional Patent Application No. 63 / 328,897, filed April 8, 2022, which is incorporated by reference as if fully set forth herein. [Background technology]

[0002] The present invention relates to the field of computing and communications, and more particularly to methods, apparatus, 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 communications systems. Such NR access and technologies, which may also be referred to as 5G and / or 6G, and / or other similar wireless communication systems and technologies, may include functionality and / or technology for reconfigurable intelligent surfaces (RIS). As described herein, the RIS may adapt to wireless environment conditions. For example, the RIS may electronically control the propagation of radio frequency (RF) signals that contact the surface of the RIS. The NR downlink (DL) beam management BM coordinates the transmission and reception point (TRP) transmission (Tx) beams and the WTRU received (Rx) beams. One or more of the following may apply: The P1 procedure may be used to enable WTRU measurements on different TRP Tx beams, e.g., to support TRP Tx beam / WTRU Rx beam selection. The P2 procedure may be used to enable WTRU measurements on different TRP Tx beams, e.g., to change inter / intra-TRP Tx beams. The P3 procedure may be used to enable WTRU measurements on the same TRP Tx beam, e.g., to change WTRU Rx beams (e.g., if the WTRU uses beamforming). Summary of the Invention

[0003] A system can be configured to perform a reconfigurable intelligent surface (RIS) assisted initial access. For example, the system can include a network node (e.g., a gNB or TRP), a RIS, and one or more radio transmit receive units (WTRUs). The network node can be configured to transmit configuration information to the RIS. For example, the configuration information can be configured to cause the RIS to reflect a contact signal (e.g., based on channel information). After configuring the RIS, the network node can transmit a synchronization block (SSB) toward the RIS. Based on the configuration information, the RIS can reflect the SSB transmitted by the network node. For example, the RIS can reflect the SSB toward the WTRU. In a particular implementation, the configuration information transmitted to the RIS can be specific to a given SSB transmission (e.g., or an SSB transmission burst). In such an implementation, the network node can transmit multiple pieces of configuration information to the RIS, each respective confirmation information associated with a respective SSB transmission.

[0004] The WTRU may detect the reflected SSB. Based on the SSB, the WTRU may acquire remaining system information (RMSI) and / or perform a random access procedure. After completion of the random access procedure, the WTRU may enter a connected state. The SSB detected by the WTRU may be associated with an index. For example, the WTRU may determine the SSB detected by a source (e.g., a network node or a RIS) based on the index. Additionally or alternatively, the WTRU may map one or more physical random access channel (PRACH) transmission timings using the index associated with the detected SSB.

[0005] The WTRU may detect a reflected SSB transmission from a RIS, where the reflected SSB is associated with an index. The index associated with the reflected SSB may be an SSB index or a candidate SSB index (e.g., an SSB transmission timing). The WTRU may determine that the reflected SSB transmission was reflected by the RIS based on the index associated with the reflected SSB transmission. For example, the WTRU may determine a source device of the reflected SSB transmission based on the index (e.g., whether the SSB transmission was reflected by the RIS or received directly from the network device). The WTRU may perform a random access procedure with the network device via the RIS based on the index.

[0006] In some embodiments, the WTRU may determine that the reflected SSB transmission has been reflected by the RIS based on a determination that an index associated with the SSB transmission is not quasi collocated (QCL) with a candidate SSB index associated with the SSB transmission.

[0007] In some embodiments, the index associated with the reflected SSB may be a candidate SSB index (e.g., an SSB transmission timing). In such embodiments, the WTRU may determine that the reflected SSB transmission was reflected by the RIS based on determining that the index associated with the SSB transmission is not quasi-co-located (QCL) with a burst set index associated with the SSB transmission.

[0008] The SSB transmission may be associated with an SSB burst transmission, which includes multiple SSB transmissions. Each of the multiple SSB transmissions may be associated with an index. The multiple SSB transmissions may include SSB transmissions that are reflected by the RIS and / or SSB transmissions that are not reflected by the RIS. In some embodiments, the spatial state of the RIS may be maintained constant during the SSB burst transmission.

[0009] The SSB burst transmission may include a reflected SSB transmission and / or multiple legacy SSB transmissions. The multiple legacy SSB transmissions may not be reflected by the RIS. The SSB burst transmission may be transmitted according to a legacy SSB transmission pattern.

[0010] The WTRU can detect a second reflected SSB transmission from the reflected RIS. The second reflected SSB transmission can be associated with a different spatial beam than the reflected SSB transmission. The reflected SSB transmission can be associated with the first SSB transmission burst from the source device. The reflected SSB transmission and / or the second reflected SSB can be associated with a second SSB burst transmission from the source device.

[0011] The second reflected SSB transmission may be associated with the same index as the reflected SSB transmission.

[0012] The number of candidate SSB indices may be greater than the number of SSB indices.

[0013] A subset of the SSB transmissions of the SSB burst transmission may be reflected by the RIS at different spatial states.

[0014] The WTRU may detect an unreflected SSB transmission. The unreflected SSB transmission may not be reflected by the RIS. The unreflected SSB transmission may not be associated with a second SSB burst transmission that includes multiple SSB transmissions. The multiple SSB transmissions of the SSB burst transmission may be reflected by the RIS. [Brief description of the drawings]

[0015] [Figure 1A] 1 is a system diagram illustrating an example communication system in which one or more disclosed embodiments may be implemented. [Figure 1B] 1 is a system diagram illustrating an example wireless transmit / receive unit (WTRU) that may be used within the communications system illustrated in FIG. 1A, according to one embodiment. [Figure 1C] 1 is a system diagram illustrating an example radio access network (RAN) and an example core network (CN) that may be used within the communication system illustrated in FIG. 1A, according to one embodiment. [Figure 1D] 1B is a system diagram illustrating a further exemplary RAN and a further exemplary CN that may be used within the communication system illustrated in FIG. 1A, according to one embodiment. [Diagram 2] FIG. 1 illustrates an example RIS-assisted wireless system. [Diagram 3] FIG. 1 illustrates an example four-element RIS. [Figure 4] FIG. 1 illustrates an embodiment relating to a passive RIS that may enable an incident / touch signal (e.g., a beam) to be reflected in multiple directions. [Diagram 5] FIG. 1 illustrates another embodiment relating to a RIS-assisted wireless system. [Figure 6] FIG. 1 illustrates an example RIS support architecture. [Figure 7A] FIG. 1 illustrates an embodiment relating to a RIS controller. [Figure 7B] FIG. 1 illustrates an embodiment relating to a RIS controller. [Figure 7C] FIG. 1 illustrates an embodiment relating to a RIS controller. [Figure 8] FIG. 1 illustrates one embodiment relating to RIS additional initial access. [Figure 9] FIG. 1 illustrates an embodiment relating to RIS additional initial access and / or backward compatibility. [Figure 10] FIG. 1 illustrates an embodiment relating to RIS additional initial access and / or backward compatibility. [Figure 11] FIG. 1 illustrates an embodiment relating to RIS additional initial access and / or backward compatibility. [Figure 12A]FIG. 1 illustrates an embodiment relating to RIS additional initial access and / or backward compatibility. [Figure 12B] FIG. 1 illustrates an embodiment relating to RIS additional initial access and / or backward compatibility. [Figure 13] FIG. 1 illustrates an embodiment relating to RIS additional initial access and / or backward compatibility. [Figure 14] FIG. 1 illustrates an example procedure associated with determining the source of a detected SSB (e.g., via the RIS-to-WTRU path or the gNB-to-WTRU). [Figure 15] FIG. 1 illustrates one embodiment relating to RIS-assisted SSB transmission. [Figure 16A] FIG. 2 illustrates an example embodiment relating to multiple SSB transmissions. [Figure 16B] FIG. 2 illustrates an example embodiment relating to multiple SSB transmissions. [Figure 17] FIG. 1 illustrates an example embodiment relating to an SSB burst set transmission; [Figure 18] FIG. 1 illustrates an example embodiment relating to an SSB burst set transmission; [Figure 19] FIG. 13 illustrates a further embodiment relating to multiple SSB burst set transmissions. [Figure 20] FIG. 13 illustrates a further embodiment relating to multiple SSB burst set transmissions. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0016] 1A is a diagram illustrating an example communications system 100 in which one or more disclosed embodiments may be implemented. Communications system 100 may be a multiple access system that provides content, such as voice, data, video, messaging, broadcasts, etc., to multiple wireless users. Communications system 100 may enable multiple wireless users to access such content through sharing of system resources, including wireless bandwidth. For example, the communications system 100 may use 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 multicarrier (FBMC), and the like.

[0017] 1A, communications 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, although it will be understood that the disclosed embodiments contemplate any number of WTRUs, base stations, networks, and / or network elements. Each of WTRUs 102a, 102b, 102c, 102d may be any type of device configured to operate and / or communicate in a wireless environment. By way of example, the WTRUs 102a, 102b, 102c, 102d, any of which may be referred to as a “station” and / or “STA,” may be configured to transmit and / or receive wireless signals, and may include user equipment (WTRU), mobile stations, fixed or mobile subscriber units, subscription-based units, pagers, mobile phones, personal digital assistants (PDAs), smartphones, laptops, netbooks, personal computers, wireless sensors, hotspots or Mi-Fi devices, Internet of Things (loT) devices, watches or other wearable, head-mounted displays (HMDs), vehicles, drones, medical devices and applications (e.g., for remote surgery), industrial devices and applications (e.g., robots and / or other wireless devices operating in an industrial and / or automated processing chain context), consumer electronics devices, devices operating in commercial and / or industrial wireless networks, and the like. Any of the WTRUs 102a, 102b, 102c, and 102d may be referred to interchangeably as a WTRU.

[0018] 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 configured to wirelessly interface with at least one of the WTRUs 102a, 102b, 102c, 102d to facilitate access to one or more communication networks, such as the CN 106 / 115, the Internet 110, and / or other networks 112. By way of example, the base stations 114a, 114b may be a base station 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, etc. Although the base stations 114a, 114b are each depicted as a single element, it will be understood that the base stations 114a, 114b may include any number of interconnected base stations and / or network elements.

[0019] The base station 114a may be part of the RAN 104 / 113, which may also include other base stations and / or network elements (not shown), such as a base station controller (BSC), a radio network controller (RNC), relay nodes, etc. The base station 114a and / or the base station 114b may be configured to transmit and / or receive wireless signals on one or more carrier frequencies, which may be referred to as cells (not shown). These frequencies may be licensed spectrum, unlicensed spectrum, or a combination of licensed and unlicensed spectrum. A cell may provide wireless service coverage for a particular geographic area, which may be relatively fixed or may change over time. A cell may be further divided into cell sectors. For example, the cell associated with the base station 114a may be divided into three sectors. Thus, in one embodiment, the base station 114a may include three transceivers, i.e., one 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, using beamforming to transmit and / or receive signals in a desired spatial direction.

[0020] The base stations 114a, 114b may communicate with one or more of the WTRUs 102a, 102b, 102c, 102d via 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).

[0021] More specifically, as noted above, the communications system 100 may be a multiple access system, but may use one or more channel access schemes, such as CDMA, TDMA, FDMA, OFDMA, SC-FDMA, etc. For example, the base stations 114a and the WTRUs 102a, 102b, 102c in the RAN 104 / 113 may implement a radio technology, such as Universal Mobile Telecommunications System (UMTS) Terrestrial Radio Access (UTRA), which may establish the air interface 115 / 116 / 117 using wideband CDMA (WCDMA). WCDMA may include communications 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 ​​Uplink Packet Access (HSUPA).

[0022] 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), which may establish the air interface 116 using Long Term Evolution (LTE) and / or LTE-Advanced (LTE-A) and / or LTE-Advanced Pro (LTE-A Pro).

[0023] In one embodiment, the base station 114a and the WTRUs 102a, 102b, 102c may implement a radio technology, such as New Radio (NR) radio access, which may establish the air interface 116 using NR technology.

[0024] 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 implement LTE radio access and NR radio access together, e.g., 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 sent to and from multiple types of base stations (e.g., eNBs and gNBs).

[0025] In other embodiments, the base station 114a and the WTRUs 102a, 102b, 102c may implement a wireless technology such as IEEE 802.11 (i.e., Wireless Fidelity, WiFi), IEEE 802.16 (i.e., Worldwide Interoperability for Microwave Access, WiMAX), CDMA2000, CDMA2000 1X, CDMA2000 EV-DO, Interim Standard 2000 (IS-2000), Interim Standard 95 (IS-95), Interim Standard 856 (IS-856), Global System for Mobile communications (GSM), Enhanced Data rates for GSM Evolution (EDGE), GSM EDGE (GERAN), or the like.

[0026] The base station 114b of FIG. 1A 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 localized area, such as an office, a home, a vehicle, a campus, an industrial facility, an air corridor (e.g., for use by drones), a road, etc. 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 yet another embodiment, the base station 114b and the WTRUs 102c, 102d may utilize a cellular-based RAT (e.g., WCDMA, CDMA2000, GSM, LTE, LTE-A, LTE-A Pro, NR, etc.) to establish a picocell or femtocell. 1A, the base station 114b may have a direct connection to the Internet 110. Thus, the base station 114b may not need to access the Internet 110 via the CN 106 / 115.

[0027] The RAN 104 / 113 may communicate with the CN 106 / 115, which may be any type of network configured to provide voice, data, application, and / or voice over internet protocol (VoIP) services to one or more of the WTRUs 102a, 102b, 102c, 102d. The data may have various quality of service (QoS) requirements, such as, for example, 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 shown in FIG. 1A, it will be appreciated that the RAN 104 / 113 and / or the CN 106 / 115 may communicate directly or indirectly with other RANs employing 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 communicate with another RAN (not shown) using GSM, UMTS, CDMA2000, WiMAX, E-UTRA, or WiFi radio technology.

[0028] 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 providing plain old telephone service (POTS). The Internet 110 may include a global system of interconnected computer networks and devices that use common communication protocols, such as the transmission control protocol (TCP), user datagram protocol (UDP), and / or the internet protocol (IP) of the TCP / IP Internet protocol suite. The networks 112 may include wired and / or wireless communication networks owned and / or operated by other service providers. For example, the networks 112 may include another CN connected to one or more RANs, which may use the same RAT as the RANs 104 / 113 or a different RAT.

[0029] Some or all of the WTRUs 102a, 102b, 102c, 102d in the communications system 100 may include multi-mode capabilities (e.g., the WTRUs 102a, 102b, 102c, 102d may include multiple transceivers for communicating with different wireless networks over different wireless links). For example, the WTRU 102c shown in FIG. 1A may be configured to communicate with a base station 114a, which may employ a cellular-based wireless technology, and a base station 114b, which may employ an IEEE 802 wireless technology.

[0030] Figure 1B is a system diagram illustrating an example WTRU 102. As shown in Figure 1B, 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 understood that the WTRU 102 may include any sub-combination of the foregoing elements while remaining consistent with an embodiment.

[0031] The processor 118 may be a general purpose processor, a special purpose processor, a conventional processor, a digital signal processor (DSP), multiple microprocessors, one or more microprocessors associated with a DSP core, a controller, a microcontroller, an Application Specific Integrated Circuits (ASIC), a Field Programmable Gate Arrays (FPGA) circuit, any other type of integrated circuit (IC), a state machine, etc. The processor 118 may perform signal coding, data processing, power control, input / output processing, and / or any other functionality that enables the WTRU 102 to operate in a wireless environment. The processor 118 may be coupled to the transceiver 120, which may be coupled to the transmit / receive element 122. Although FIG. 1B depicts the processor 118 and the transceiver 120 as separate components, it will be understood that the processor 118 and the transceiver 120 may be integrated together in an electronic package or chip.

[0032] The transmit / receive element 122 may be configured to transmit or receive signals to or from a base station (e.g., base station 114a) over the air interface 116. For example, in one embodiment, the transmit / receive element 122 may be an antenna configured to transmit and / or receive RF signals. In one embodiment, the transmit / receive element 122 may be an emitter / detector configured to transmit and / or receive, for example, IR, UV, or visible light signals. In yet another embodiment, the transmit / receive element 122 may be configured to transmit and / or receive both RF and light signals. It will be appreciated that the transmit / receive element 122 may be configured to transmit and / or receive any combination of wireless signals.

[0033] 1B as a single element, the WTRU 102 may include any number of transmit / receive elements 122. More specifically, the WTRU 102 may employ MIMO technology. Thus, in one embodiment, the WTRU 102 may include two or more transmit / receive elements 122 (e.g., multiple antennas) for transmitting and receiving wireless signals over the air interface 116.

[0034] The transceiver 120 may be configured to modulate signals transmitted by the transmit / receive element 122 and demodulate signals received by the transmit / receive element 122. As mentioned above, the WTRU 102 may have multi-mode capabilities. Thus, the transceiver 120 may include multiple transceivers to enable the WTRU 102 to communicate via multiple RATs, such as, for example, NR and IEEE 802.11.

[0035] The processor 118 of the WTRU 102 may be coupled to and may receive user-entered 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 non-removable memory 130 and / or removable memory 132. The non-removable memory 130 may include random-access memory (RAM), read-only memory (ROM), a hard disk, or any other type of memory storage device. The removable memory 132 may include a subscriber identity module (SIM) card, a memory stick, a secure digital (SD) memory card, etc. In other embodiments, the processor 118 may access information from and store data in memory that is not physically located on the WTRU 102, such as on a server or home computer (not shown).

[0036] The processor 118 may receive power from the power source 134 and may be configured to distribute and / or control the power to other components in the WTRU 102. The power source 134 may be any suitable device for providing power to the WTRU 102. For example, the power source 134 may include one or more dry batteries (e.g., nickel-cadmium (NiCd), nickel-zinc (NiZn), nickel metal hydride (NiMH), lithium-ion (Li-ion), etc.), solar cells, fuel cells, etc.

[0037] The processor 118 may also be coupled to a 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, information from the GPS chipset 136, the WTRU 102 may receive location information from base stations (e.g., base stations 114a, 114b) over the air interface 116 and / or determine its location based on the timing of signals being received from two or more nearby base stations. It will be appreciated that the WTRU 102 may obtain location information by way of any suitable location determination method while remaining consistent with an embodiment.

[0038] The processor 118 may further be coupled to other peripherals 138, which may include one or more software and / or hardware modules that provide additional features, functionality, and / or wired or wireless connectivity. For example, the peripherals 138 may include an accelerometer, an electronic compass, a satellite transceiver, a digital camera (for photos and / or videos), a universal serial bus (USB) port, a vibration device, a television transceiver, a hands-free headset, a Bluetooth® module, a frequency modulated (FM) radio unit, a digital music player, a media player, a video game player module, an Internet browser, a virtual reality and / or augmented reality (VR / AR) device, an activity tracker, and the like. The peripherals 138 may include one or more sensors, which may be one or more of a gyroscope, an accelerometer, a Hall effect sensor, a magnetometer, an orientation sensor, a proximity sensor, a temperature sensor, a time sensor, a geolocation sensor, an altimeter, a light sensor, a touch sensor, a magnetometer, a barometer, a gesture sensor, a biometric sensor, and / or a humidity sensor.

[0039] The WTRU 102 may include a full-duplex radio where transmission and reception of some or all of the signals associated with a particular subframe (e.g., for both the UL (e.g., for transmission) and the downlink (e.g., for reception) may be parallel and / or simultaneous. The full-duplex radio may include an interference management unit 139 to reduce and or substantially eliminate self-interference via either hardware (e.g., a choke) or signal processing via a processor (e.g., via a separate processor (not shown) or processor 118). In one embodiment, the WRTU 102 may include a half-duplex radio for transmission and reception of some or all of the signals (e.g., associated with a particular subframe for either the UL (e.g., for transmission) or the downlink (e.g., for reception)).

[0040] 1C is a system diagram illustrating the RAN 104 and the CN 106, according to one embodiment. As mentioned above, the RAN 104 may employ E-UTRA radio technology to communicate with the WTRUs 102a, 102b, 102c over the air interface 116. The RAN 104 may also communicate with the CN 106.

[0041] The RAN 104 may include eNodeBs 160a, 160b, 160c, although it will be understood that the RAN 104 may include any number of eNodeBs while remaining consistent with an embodiment. The eNodeBs 160a, 160b, 160c may each include one or more transceivers for communicating with the WTRUs 102a, 102b, 102c over the air interface 116. In an embodiment, the eNodeBs 160a, 160b, 160c may implement MIMO technology. Thus, the eNodeB 160a may, for example, use multiple antennas to transmit wireless signals to and / or receive wireless signals from the WTRU 102a.

[0042] Each of the eNodeBs 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. As shown in FIG 1C, the eNodeBs 160a, 160b, 160c may communicate with one another via an X2 interface.

[0043] 1C may include a mobility management entity (MME) 162, a serving gateway (SGW) 164, and a packet data network (PDN) gateway (or PGW) 166. Although each of the foregoing elements is depicted as part of the CN 106, it will be understood that any of these elements may be owned and / or operated by an entity other than the CN operator.

[0044] The MME 162 may be connected to each of the eNodeBs 162a, 162b, 162c in the RAN 104 via an S1 interface and may function as a control node. For example, the MME 162 may be responsible for authenticating users of the WTRUs 102a, 102b, 102c, activating / deactivating bearers, selecting a particular serving gateway during initial attachment 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.

[0045] The SGW 164 may be connected to each of the eNodeBs 160a, 160b, 160c in the RAN 104 via an S1 interface. The SGW 164 may generally route and forward user data packets to and from the WTRUs 102a, 102b, 102c. The SGW 164 may perform other functions, such as anchoring the user plane during inter-eNodeB handover, triggering paging when DL data is available to the WTRUs 102a, 102b, 102c, and managing and storing the context of the WTRUs 102a, 102b, 102c.

[0046] The SGW 164 may be connected to a 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.

[0047] 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 communicate with an IP gateway (e.g., an IP multimedia subsystem (IMS) server) that serves as an interface between the CN 106 and the PSTN 108. In addition, the CN 106 may provide the WTRUs 102a, 102b, 102c with access to other networks 112, which may include other wired and / or wireless networks owned and / or operated by other service providers.

[0048] Although the WTRU is illustrated in FIGS. 1A-1D as a wireless terminal, it is contemplated that in certain representative embodiments such a terminal may use a wired communications interface (e.g., temporarily or permanently) with the communications network.

[0049] In an exemplary embodiment, the other network 112 may be a WLAN.

[0050] A WLAN in infrastructure basic service set (BSS) mode may have an access point (AP) of the BSS and one or more stations (STAs) associated with the AP. The AP may have access or interface to a distribution system (DS) or another type of wired / wireless network that carries traffic into and / or out of the BSS. Traffic originating outside the BSS to the STA may arrive through the AP and be sent to the STA. Traffic originating from the STA to a destination outside the BSS may be sent to the AP to be sent to the respective destination. Traffic between STAs within the BSS may be sent, for example, through the AP, where the source STA may send traffic to the AP, and the AP may send traffic to the destination STA. Traffic between STAs within the BSS may be considered and / or referred to as peer-to-peer traffic. Peer-to-peer traffic may be sent between (e.g., directly between) the source STA and the destination STA using a direct link setup (DLS). In certain representative embodiments, the DLS may use 802.11e DLS or 802.11z tunneled DLS (TDLS). A WLAN using an Independent BSS (IBSS) mode may not have an AP, and STAs (e.g., all of the STAs) within or using the IBSS may communicate directly with each other. The IBSS mode of communication may be referred to herein as an "ad-hoc" communication mode.

[0051] When using an 802.11ac infrastructure mode of operation or a similar mode of operation, an AP may transmit a beacon 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 that is dynamically set via signaling. The primary channel may be the operating channel of the BSS, but may be used by STAs to establish a connection with the AP. In certain representative embodiments, for example, in an 802.11 system, Carrier Sense Multiple Access with Collision Avoidance (CSMA / CA) may be implemented. With CSMA / CA, STAs (e.g., all STAs), including the AP, may sense the primary channel. If the primary channel is sensed / detected and / or determined to be busy by a particular STA, the particular STA may back off. One STA (e.g., only one station) may transmit at any given time in a given BSS.

[0052] A High Throughput (HT) STA may use a 40 MHz wide channel for communication, which may be formed, for example, through a combination of a primary 20 MHz channel and adjacent or non-adjacent 20 MHz channels.

[0053] A Very High Throughput (VHT) STA may support 20 MHz, 40 MHz, 80 MHz, and / or 160 MHz wide channels. A 40 MHz and / or 80 MHz channel may be formed by combining multiple adjacent 20 MHz channels. A 160 MHz channel may be formed by combining eight consecutive 20 MHz channels or by combining two non-adjacent 80 MHz channels, which may be referred to as an 80+80 configuration. For the 80+80 configuration, after channel encoding, the data may pass through a segment parser that may split the data into two streams. Inverse Fast Fourier Transform (IFFT) processing and time domain processing may be performed separately on each stream. The streams may be mapped to two 80 MHz channels and the data may be transmitted by the transmitting STA. At the receiver of the receiving STA, the operations described above for the 80+80 configuration may be reversed and the combined data may be sent to the Medium Access Control (MAC).

[0054] Sub-1 GHz operating modes are supported by 802.11af and 802.11ah. Channel operating bandwidths and carriers are reduced in 802.11af and 802.11ah compared to those used in 802.11n and 802.11ac. 802.11af supports 5 MHz, 10 MHz, and 20 MHz bandwidths in TV White Space (TVWS) spectrum, and 802.11ah supports 1 MHz, 2 MHz, 4 MHz, 8 MHz, and 16 MHz bandwidths using non-TVWS spectrum. According to a representative embodiment, 802.11ah may support meter-type control / machine-type communication, such as MTC devices in macro coverage areas. MTC devices may have limited capabilities, including certain capabilities, such as support for certain and / or limited bandwidths (e.g., only supporting these). MTC devices may include batteries with above-threshold battery life (e.g., to maintain very long battery life).

[0055] WLAN systems that may support multiple channels and channel bandwidths, such as 802.11n, 802.11ac, 802.11af, and 802.11ah, include a channel that may be designated as a primary channel. The primary channel may have a bandwidth equal to the maximum common operating bandwidth supported by all STAs in the BSS. The bandwidth of the primary channel may be configured and / or limited by the STAs among all STAs operating in the BSS that support the smallest bandwidth operating mode. In an 802.11ah embodiment, the primary channel may be 1 MHz wide for STAs (e.g., MTC-type devices) that support (e.g., only) the 1 MHz mode, even if the AP and other STAs in the BSS support 2 MHz, 4 MHz, 8 MHz, 16 MHz, and / or other channel bandwidth operating modes. Carrier sensing and / or Network Allocation Vector (NAV) configuration may depend on the status of the primary channel. For example, if the primary channel is active due to a STA (that only supports the 1 MHz mode of operation) transmitting to the AP, the entire available frequency band may be considered active even though most of the frequency band may remain dormant and available.

[0056] In the United States, the available frequency bands that can be used by 802.11ah are 902MHz to 928MHz. In South Korea, the available frequency bands are 917.5MHz to 923.5MHz. In Japan, the available frequency bands are 916.5MHz to 927.5MHz. The total bandwidth available for 802.11ah is 6MHz to 26MHz depending on the country code.

[0057] 1D is a system diagram illustrating the RAN 113 and the CN 115, according to one embodiment. As mentioned above, the RAN 113 may employ NR radio technology to communicate with the WTRUs 102a, 102b, 102c over the air interface 116. Further, the RAN 113 may communicate with the CN 115.

[0058] The RAN 113 may include gNBs 180a, 180b, 180c, although it will be understood that the RAN 113 may include any number of gNBs while remaining consistent with an embodiment. The gNBs 180a, 180b, 180c may each include one or more transceivers for communicating with the WTRUs 102a, 102b, 102c over the air interface 116. In an embodiment, the gNBs 180a, 180b, 180c may implement MIMO technology. For example, the gNBs 180a, 108b may utilize beamforming to transmit signals to and / or receive signals from the gNBs 180a, 180b, 180c. Thus, the gNB 180a may transmit and / or receive wireless signals to and from the WTRU 102a, for example, using multiple antennas. 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 gNBs 180a and 180b (and / or gNB 180c).

[0059] The WTRUs 102a, 102b, 102c may communicate with the gNBs 180a, 180b, 180c using transmissions associated with scalable numerology. For example, the OFDM symbol spacing and / or OFDM subcarrier spacing may vary for different transmissions, different cells, and / or different portions of the wireless transmission spectrum. The WTRUs 102a, 102b, 102c may communicate with the gNBs 180a, 180b, 180c using subframes or transmission time intervals (TTIs) of different or scalable lengths (e.g., including different numbers of OFDM symbols and / or lasting different lengths of absolute time).

[0060] The gNBs 180a, 180b, 180c may be configured to communicate with the WTRUs 102a, 102b, 102c in a standalone configuration and / or a non-standalone configuration. In a standalone configuration, the WTRUs 102a, 102b, 102c may communicate with the gNBs 180a, 180b, 180c without accessing another RAN (e.g., eNodeBs 160a, 160b, 160c, etc.). In a standalone configuration, the WTRUs 102a, 102b, 102c may utilize 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 unlicensed bands. In a non-standalone configuration, the WTRUs 102a, 102b, 102c may communicate with and connect to a gNB 180a, 180b, 180c while also communicating with and connecting to another RAN, such as an eNodeB 160a, 160b, 160c. For example, the WTRUs 102a, 102b, 102c may implement DC principles 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 eNodeBs 160a, 160b, 160c may act as mobility anchors for the WTRUs 102a, 102b, 102c, and the gNBs 180a, 180b, 180c may provide additional coverage and / or throughput for serving the WTRUs 102a, 102b, 102c.

[0061] Each of the gNBs 180a, 180b, 180c may be associated with a particular cell (not shown) and may be configured to handle radio resource management decisions, handover decisions, scheduling of users in the UL and / or DL, support for network slicing, dual connectivity, interworking between NR and E-UTRA, routing of user plane data to User Plane Functions (UPFs) 184a, 184b, routing of control plane information to Access and Mobility Management Functions (AMFs) 182a, 182b, etc. As shown in FIG. 1D, the gNBs 180a, 180b, 180c may communicate with each other via an Xn interface.

[0062] 1D may include at least one AMF 182a, 182b, at least one UPF 184a, 184b, at least one Session Management Function (SMF) 183a, 183b, and possibly a Data Network (DN) 185a, 185b. Although each of the foregoing elements is illustrated as part of the CN 115, it will be understood that any of these elements may be owned and / or operated by an entity other than the CN operator.

[0063] The AMF 182a, 182b may be connected to one or more of the gNBs 180a, 180b, 180c in the RAN 113 via an N2 interface and may function as a control node. For example, the AMF 182a, 182b may be responsible for authenticating users of the WTRUs 102a, 102b, 102c, supporting network slicing (e.g., handling different PDU sessions with different requirements), selecting a particular SMF 183a, 183b, managing registration areas, terminating NAS signaling, mobility management, etc. The network slices may be used by the AMF 182a, 182b to customize the CN support of the WTRUs 102a, 102b, 102c based on the type of service utilizing the WTRUs 102a, 102b, 102c. For example, different network slices may be established for different use cases such as services relying on ultra-reliable low latency (URLLC) access, services relying on enhanced massive mobile broadband (eMBB) access, services for machine type communication (MTC) access, 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.

[0064] The SMFs 183a, 183b may be connected to the AMFs 182a, 182b in the CN 115 via an N11 interface. The SMFs 183a, 183b may also be connected to the UPFs 184a, 184b in the CN 115 via an N4 interface. The SMFs 183a, 183b may select and control the UPFs 184a, 184b and configure the routing of traffic through the UPFs 184a, 184b. The SMFs 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 notification, etc. The PDU session type may be IP-based, non-IP-based, Ethernet-based, etc.

[0065] The UPFs 184a, 184b may be connected to one or more of the gNBs 180a, 180b, 180c in the RAN 113 via an N3 interface, which may provide the WTRUs 102a, 102b, 102c with access to packet-switched networks, such as the Internet 110, to facilitate communications between the WTRUs 102a, 102b, 102c and IP-enabled devices. The UPFs 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.

[0066] The CN 115 may facilitate communication with other networks. For example, the CN 115 may include or communicate with an IP gateway (e.g., an IP Multimedia Subsystem (IMS) server) that serves as an interface between the CN 115 and the PSTN 108. In addition, the CN 115 may provide the WTRUs 102a, 102b, 102c with access to other networks 112, which may include other wired and / or wireless networks owned and / or operated by other service providers. In an embodiment, the WTRUs 102a, 102b, 102c may be connected to local data networks (DNs) 185a, 185b through the UPFs 184a, 184b via an N3 interface to the UPFs 184a, 184b and an N6 interface between the UPFs 184a, 184b and the DNs 185a, 185b.

[0067] 1A-1D and the corresponding description thereof, one or more or all of the functions described herein with respect to one or more of the WTRUs 102a-d, base stations 114a-b, eNode-Bs 160a-c, MME 162, SGW 164, PGW 166, gNBs 180a-c, AMFs 182a-ab, UPFs 184a-b, SMFs 183a-b, DNs 185a-b, and / or any other devices described herein may be performed by one or more emulation devices (not shown). The emulation devices may be one or more devices configured to emulate one or more or all of the functions described herein. For example, the emulation devices may be used to test other devices and / or to simulate network and / or WTRU functions.

[0068] The emulation device may be designed to implement one or more tests of other devices in a lab environment and / or an operator network environment. For example, one or more emulation devices may perform one or more or all functions while fully or partially implemented and / or deployed as part of a wired and / or wireless communication network to test other devices in the communication network. One or more emulation devices may perform one or more or all functions while temporarily implemented / deployed as part of a wired and / or wireless communication network. The emulation device may be directly coupled to another device for testing purposes and / or may use terrestrial wireless communication to implement the tests.

[0069] The one or more emulation devices may perform one or more functions, inclusive, while not being implemented / deployed as part of a wired and / or wireless communication network. For example, the emulation devices may be utilized in test scenarios in a test lab and / or in an undeployed (e.g., test) wired and / or wireless communication network to implement testing of one or more components. The one or more emulation devices may be test equipment. Direct RF coupling and / or wireless communication via RF circuitry (which may include, for example, one or more antennas) may be used by the emulation devices to transmit and / or receive data.

[0070] During initial access, one or more of the following may occur: A P1 (e.g., beam selection) procedure may focus on initial acquisition (e.g., based on synchronization signal blocks (SSBs)) for an idle WTRU. The SSBs may include a primary synchronization signal (PSS), a secondary synchronization signal (SSS), and / or a physical broadcast channel (PBCH). Periodic SSB beam scanning may be performed by the network (e.g., gNB) at a certain interval (e.g., SSB periodicity may be 20, 40, 80, and / or 160 ms). Beam scanning may be implemented by the WTRU, for example, to determine an optimal receiving beam. The SSBs of the SSB burst set may be multiplexed in the time domain.

[0071] For subsequent downlink transmissions (DLTx), the WTRU may assume that the receiving (Rx) beam used to acquire the SSB is a suitable beam for receiving the subsequent downlink transmission. The WTRU may use the Tx beam used to transmit a physical random access channel (PRACH) transmission. Beam scanning for SSB transmissions may enable, for example, receiver beam scanning for reception of uplink random access transmissions and / or downlink beamforming for random access responses. The P1 (e.g., beam selection) procedure may be completed when the random access procedure is completed.

[0072] In a particular initial access procedure (e.g., NR initial access procedure), one or more of the following may apply: In an embodiment, the WTRU may search for an SSB to obtain a physical cell ID (PCI) and / or downlink (DL) synchronization. The WTRU may decode a master information block (MIB). The WTRU may obtain a physical downlink control channel (PDCCH) configuration. The PDCCH may be used to obtain remaining system information (RMSI). The control resource set (CORESET) #0 configuration of the RMSI may be associated with the SSB of the SSB burst set. The WTRU may read the RMSI from the system information block (SIB) #1 and decode the public land mobile network (PLMN) ID, cell selection parameters, random access channel (RACH) parameters, etc. The WTRU may perform random access and obtain UL synchronization. The UL synchronization may include a timing advance (TA). The WTRU may establish a radio resource control (RRC) connection.

[0073] The SSB candidate index (e.g., NR) may be one or more of the following: The half frame may include an SSB. The first symbol index of the candidate SSB may be determined according to the sub-carrier spacing (SCS) of the SSB. Index 0 may correspond to the first symbol of the first slot of the half frame. L max may indicate (eg, in NR) the maximum number of SSB identifiers (IDs) in an SSB burst set.

[0074]

number

[0075]

number

[0076]

number

[0077] [Table 1]

[0078] For SSB mapping (e.g., NR) to PRACH transmission timing, one or more of the following may apply: Parameters such as ssB-per-RACH-Occasion and CB-PreamblesPerSSB may configure the N SSBs (SSB-per-rach-occasion) that may be associated with the PRACH transmission timing, and the number of preambles each SSB uses at each valid PRACH transmission timing (e.g., based on contention (CB-preambles-per-SSB)).

[0079] There are two possible configurations related to N: if N<1, one SSB can be mapped to 1 / N consecutive valid PRACH transmission timings, and / or if N≧1, N SSBs can be mapped to one PRACH transmission timing.

[0080] For reconfigurable intelligent surfaces (RIS), one or more of the following may apply: RIS may create a smart propagation environment (e.g., for future wireless communication systems). The surface of a RIS may, for example, intelligently change the wireless environment (e.g., by electronically controlling the propagation of incident / touching signals in a programmable way to improve system performance). Introducing a RIS into a wireless communication system may allow for the control of scattering in the environment.

[0081] As described herein, a RIS can include one or more (e.g., multiple) elements (e.g., sub-wavelength sized unit elements) that can be electronically controlled. In certain implementations, the RIS elements can include metasurfaces and / or reflective arrays. The RIS elements can be closely spaced, which can allow the RIS to operate as a scatterer (e.g., a smart scatterer). Each element can modify the properties (e.g., reflection, refraction, and / or absorption) of the contact signal. The RIS elements can be passive, active, and / or semi-active. For example, a passive element can passively reflect a signal without amplification. For example, an active element can be capable of actively reflecting a signal with amplification.

[0082] FIG. 2 illustrates an example RIS-assisted wireless system 200. The RIS-assisted wireless system 200 may include a transmitter 202 (e.g., a gNB and / or a TRP), a RIS 204, and a receiver 206 (e.g., a WTRU). With reference to the embodiment illustrated in FIG. 2, a RIS 208 may be disposed between the transmitter 202 and the receiver 206, and (e.g., in addition to a direct link 210 between the transmitter 202 and the receiver 206), another link 212a-b runs between the two nodes through the RIS 204. Both links (e.g., the transmitter-receiver link 210 and the link 212a-b between the transmitter 202 and the receiver 206 through the RIS 204) can improve overall system performance when properly controlled.

[0083] The RIS 204 may be controlled via a RIS controller 208, which may be integrated into the RIS 204 or may be separate from the RIS 204 (e.g., as seen in FIG. 2). The RIS controller 208 may be able to individually control elements of the RIS 204, e.g., after receiving certain control signals from the transmitter 202 (e.g., gNB and / or TRP) and / or the receiver 206 (e.g., WTRU).

[0084] FIG. 3 illustrates an example four-element RIS 302. A RIS controller 304 may be connected to elements 306a-d (e.g., all elements) of the RIS 302. The RIS controller 304 may control the respective impedances (e.g., Z N ), the phase shift of the incident signal and / or the touch signal can be changed to route them in a particular direction.

[0085] The RIS 302 may be of multiple types, e.g., passive RIS, active RIS, and / or semi-active RIS. A passive RIS may include, e.g., passive elements (e.g., diodes, transmission / delay lines, lumped circuits, etc.) and may adjust the phase shift for each RIS element individually or for groups of RIS elements simultaneously. As described herein, a passive RIS may reflect the touch signal by adjusting the phase shift and / or constructively overlapping and enhancing the received signals from various paths. Furthermore, e.g., due to the passive nature of the RIS elements, a passive RIS may use minimal power (e.g., near zero power). A semi-active RIS, or an active RIS, may include power amplification and phase adjustment functions for the touch signal. For example, with reference to a semi-active RIS, e.g., (e.g., also known and referred to herein as an active-passive hybrid RIS), one or more active elements of the overall RIS element may support additional application functions. One or more of the active elements may be capable of both amplification and phase adjustment. The remaining elements of the RIS may be passive, providing only phase adjustment. For example, the elements of the active RIS (e.g., all elements) may be active elements capable of providing both amplification and phase gain.

[0086] With reference to implementations including a passive RIS, amplitude configuration may not be used in the beam selection process (e.g., P1 procedure). Additionally or alternatively, RIS-assisted SSB may be based on non-amplified tuning, such as reflection. In such implementations, elements of the RIS may be controlled by a RIS controller, for example, to modify the electromagnetic properties of the reflected signal (e.g., apply a phase shift). FIG. 4 illustrates one embodiment relating to a passive RIS 402 that may enable the incident / contact signal 404 (e.g., a beam) to be reflected in multiple directions. As seen in FIG. 4, the signal transmitted from the transmitter 406 (e.g., gNB and / or TRP) may be passively controlled without amplification.

[0087] With reference to implementations including an active RIS 402, configuration information may be transmitted (e.g., from a network) to the RIS 402 and / or to the RIS controller 408. For example, the configuration information may include amplitude configuration, which may be used in the beam selection process. In such implementations, the RIS 402 aided SSB may be actively reflected, such as by amplification tuning, by reflection. Elements of the RIS 402 may be controlled by the RIS controller 408, for example, to modify the electromagnetic properties of the reflected signal (e.g., apply a phase shift).

[0088] In a particular network (e.g., NR), the WTRU 410 may perform initial access before entering an RRC connected state / mode for data reception and data transmission. During the initial access phase, the WTRU 410 may detect synchronization signal blocks (SSBs) to obtain system information (SI), establish a beam-enabled link based on SSBs in beam scanning bursts (e.g., SSB bursts and / or burst sets) transmitted from the network (e.g., gNB and / or TRP), and / or obtain frequency and / or timing synchronization. For example, the SSB burst set may cover some spatial area with a set of beams according to a predefined interval (e.g., candidate SSB index).

[0089] Functions of the RIS 402 may include reflecting the incident beam 404 (e.g., in a desired direction) such that coverage and reception quality are enhanced. For example, if the RIS 402 is implemented in a given wireless communication system, the WTRU 410 may detect SSBs from multiple wireless propagation paths during initial access (e.g., from the RIS-to-WTRU path, the gNB / TRP-WTRU path, and / or from both the RIS-to-WTRU path and the gNB / TRP-WTRU path).

[0090] As an example (e.g., for mmWave and above frequency ranges), the WTRU may be blocked by an obstacle so that the WTRU is out of gNB coverage and cannot receive / obtain the current initial access and beam selection.

[0091] 5, for example, illustrates an example where an obstruction 502 is present (e.g., between a gNB and / or a TRP 504 and a WTRU 506). The WTRU 506 may be reached with assistance from a RIS 508. The WTRU 506 may perform initial access, for example, using the assistance of the RIS 508 to achieve timing and frequency synchronization and / or initial beam selection. However, to provide assistance, the RIS 508 may be configured to reflect the SSB 510 in the appropriate spatial direction (e.g., so that the WTRU 506 can detect the SSB 510).

[0092] For example, additional SSBs may be used to allow the RIS 508 to perform beam scanning and extend coverage. However, such signaling to enable assistance of the RIS 508 may not be defined and / or provided. One or more of the techniques described herein may be used to enable assistance of the RIS 508 during initial access and / or to take into account various radio propagation paths (e.g., from the RIS-to-WTRU path, the gNB / TRP-WTRU path, and / or from both the RIS-to-WTRU path and the gNB / TRP-WTRU path).

[0093] The initial access may be performed with the assistance of the RIS 508 (e.g., RIS 508-assisted initial access). For example, one or more of the following may be applied, including RIS 508-assisted SSB transmission: The candidate SSB index may be greater than the SSB index. For SSB index repetition (e.g., towards the same RIS), redundant candidate SSB indexes may be used. Additionally or alternatively, multiple SSB indexes may be used towards the same RIS 508, and the RIS controller 512 may apply a given configuration on the candidate SSB index to reflect the SSB 514. Multiple SSB burst sets may be broadcast by the network (e.g., gNB / TRP), and one or more (e.g., several) burst sets may be used for the RIS 508. The WTRU 506 may determine the RIS-to-WTRU path or the gNB / TRP-to-WTRU path based on the detected SSBs in the burst set.

[0094] The PRACH transmission may be performed with the assistance of the RIS 508 (eg, a RIS 508-assisted PRACH). For example, one or more RIS 508-assisted SSB and PRACH mapping rules may be provided.

[0095] For an architecture related to a RIS-assisted system (e.g., for performing RIS-assisted initial access), one or more of the following may be applicable: One or more radio links and / or radio propagation paths (e.g., between a gNB, a RIS, and / or a WTRU) may be defined. As described herein, the RIS-assisted system may be a hierarchical system (e.g., a three-tier system including a gNB / TRP, a RIS, and a WTRU). For example, FIG. 6 illustrates an example RIS-assisted architecture including a gNB / TRP 602, a RIS 604, and a WTRU 606. As seen in FIG. 6, there may be multiple (e.g., two) paths between the gNB / TRP 602 and the WTRU 606. For example, a first path may be a path that does not include the RIS 604 (e.g., a direct path 608 from the gNB / TRP 602 to the WTRU 606), and a second path 610-612 may be a path that includes the RIS 604 (e.g., a reflected path 612 between the RIS 604 and the WTRU 606). For example, as illustrated in FIG. 6, the reflection path 612 between the RIS 604 and the WTRU 606 may be controlled by the network (e.g., the gNB / TRP 602), e.g., via the RIS controller 614.

[0096] As described herein, one or more radio links may be defined. A first link may include a link between a network (e.g., gNB / TRP 602) and a RIS 604, which may be referred to as a fronthaul link 610. A second link may include a link between a network (e.g., gNB / TRP 602) and a WTRU 606, which may be referred to as an access link 608. One or more paths may also be defined. In an embodiment, a first path may include a path between a gNB / TRP 602 and a RIS 604 (e.g., a gNB-to-RIS path). A second path may include a path between a gNB / TRP 602 and a WTRU 606 (e.g., a gNB / TRP-to-WTRU path). A third path may include a path between a RIS and a WTRU (e.g., a RIS-to-WTRU path).

[0097] With respect to the fronthaul link 610, one or more of the following may apply: The fronthaul link 610 may represent a control link between the gNB / TRP 602 and the RIS 604 and / or the RIS controller 614. The fronthaul link 610 may carry control signals between the gNB and / or the TRP 602 and the RIS controller 614 (e.g., bidirectionally). For example, the control signals carried by the fronthaul link 610 may be used to configure the RIS controller 614 in the gNB / TRP-RIS direction. Additionally or alternatively, the control signals carried by the fronthaul link 610 may be used to send feedback and configuration information in the RIS-gNB / TRP direction.

[0098] For the access link 608, one or more of the following may apply: The access link 608 may be distinguished by a propagation path (e.g., a radio propagation path) between the gNB / TRP 602 and the WTRU 606. As described herein, a path between the gNB / TRP 602 and the WTRU 606 that does not include RIS 604 assistance may be denoted as a gNB / TRP-to-WTRU path. Similarly, a path between the gNB / TRP 602 and the WTRU 606 that includes RIS 604 assistance (e.g., a reflected path from the RIS 604 to the WTRU 606) may be denoted as a RIS-to-WTRU path. The access link may carry UL and DL data and control channels (e.g., PDCCH, PDSCH, PUCCH, and / or PUSCH) from the gNB / TRP 602 and / or to the WTRU 606.

[0099] As described herein, the RIS controller 614 may be used to perform the RIS 604 assistance. One or more of the following may apply: The RIS-WTRU reflection path 612 may be controlled by the system via the RIS controller 614. For example, the RIS controller 614 may receive control signals, for example, over the gNB / TRP 602-to-RIS 604 control path. For example, the RIS controller 614 may be implemented by a mobile terminal (MT), a distribution unit (DU), and / or a RAN intelligent controller (RIC).

[0100] 7A, 7B, and 7C illustrate embodiments related to a RIS controller. When the RIS controller is implemented by an MT 702a (e.g., an MT RIS controller), one or more of the following may apply: As seen in FIG. 7A, an MT 702a-based RIS controller may act as a WTRU 704a, and the MT 702a is connected to a gNB / TRP 706a, e.g., through a fronthaul link 708a. The gNB / TRP 706a may have additional functionality, e.g., to support RIS 710a-based MT 702a operation. Each RIS controller may be connected to multiple gNBs / TRPs 706a (e.g., having RIS-based functionality). For example, a RIS controller may be configured for dual connectivity (e.g., NR dual connectivity). Additionally or alternatively, each RIS controller may be connected to multiple RISs 710a.

[0101] When the RIS controller is implemented by a DU702b (e.g., a DU RIS controller), one or more of the following may apply: As seen in FIG. 7B, a DU702b-based RIS controller may behave as a network node (e.g., a gNB / TRP 706b). As seen in FIG. 7B, a DU702b-based RIS controller type may operate as a gNB / TRP 706b with a split protocol stack. For example, a DU702b-based RIS controller may be employed with an active RIS 710b array.

[0102] When the RIS controller is implemented by a RIC702c (e.g., a RIC-based RIS controller), one or more of the following may apply: An exemplary RIC702c-based RIS controller is illustrated in FIG. 7C. As seen in FIG. 7C, the RIC702c-based RIS controller may include a processing unit incorporating one or more applications that may support, for example, RIS control functions. For example, the RIC702c-based RIS controller may have near real-time (near-RT) RIC702c control functions. The RIC702c-based controller may implement certain procedures for hosting the configuration settings of the RIS710c array and / or for exchanging control procedures with the gNB / TRP 706c (e.g., via Universal Software Radio Peripheral (USRP) connectivity). The gNB / TRP 706c may also include additional functions that support the RIC702c-based RIS controller.

[0103] As described herein, one or more RIS types may be used to provide assistance during initial access. In certain implementation examples, information regarding the type of RIS (e.g., RIS capabilities and / or class) that provides assistance may be signaled to the gNB / TRP (e.g., so that the gNB / TRP knows the capabilities of the RIS before the RIS is activated). Based on the RIS type that provides assistance, the network may configure the RIS controller to set up the RIS configuration. Based on the RIS type that provides assistance, the RIS controller may configure and / or control the RIS array and / or elements according to the network configuration. The network (e.g., via the gNB) may control the RIS controller based on received information regarding the RIS type and / or RIS capabilities. Additionally or alternatively, the RIS controller may report capabilities such as processing time (e.g., time from receiving control information and / or configuration information to configuring the RIS in the network). The RIS controller may determine or otherwise obtain TDD and / or FDD and / or slot format indication (SFI) associated with a group of WTRUs. The RIS can use this information to appropriately reflect incident and / or contact signals, for example, for the DL, UL, and / or flexible slot structures.

[0104] As described herein, RIS-assisted initial access may be performed. One or more of the following may apply: A network node (e.g., gNB / TRP) may be associated with K beams (e.g., SSBs). The beams may be associated with a default and / or initial RIS configuration, for example, when the WTRU performs initial access. As described herein, RIS-assisted SSB may refer to an SSB that is reflected and / or beamformed by the RIS.

[0105] FIG. 8 illustrates an embodiment relating to a RIS-added initial access procedure 800. With respect to initial access, one or more of the following may apply: An initial configuration of the RIS controller and the RIS may be performed. At 802, when the RIS is first deployed or powered on, the RIS controller may perform a synchronization procedure. In an embodiment, the synchronization procedure may include obtaining time and frequency synchronization with the gNB / TRP, acquiring MIB and SIB, and / or completing beam pairing with the gNB / TRP. Additionally or alternatively, the time and frequency synchronization with the gNB / TRP may be configured (e.g., manually configured) at the time of deployment and / or via an operator's RIS deployment configuration procedure between the gNB / TRP and the RIS. Once the initial configuration is completed, the RIS controller may receive RIS control messages from the gNB / TRP. For example, if the type of the RIS controller is a MT RIS controller, the MT RIS controller may enter an RRC connected state and / or may receive RIS control messages.

[0106] At 804, the gNB / TRP may transmit the SSB and / or RMSI according to a predetermined RIS-assisted SSB transmission scheme (e.g., as described further herein). For example, if the WTRU is out of coverage of the gNB / TRP (e.g., due to obstructions), the WTRU may not receive the SSB and / or RMSI transmitted directly by the gNB / TRP.

[0107] At 806, the RIS can reflect the incoming and / or incoming SSB and / or RMSI according to the particular RIS-assisted SSB transmission scheme used in the system, as described herein.

[0108] At 808, the WTRU may perform a cell search procedure, detect SSBs reflected by the RIS, and / or acquire RMSI. At 810, the WTRU may perform a random access procedure. For example, based on the detected candidate SSB indices and / or corresponding associations, the WTRU may determine associated RACH resources and / or RACH preamble indices (e.g., a subset of RACH resources and / or a subset of RACH preamble indices).

[0109] At 812, after the random access procedure is completed, a communication link between the WTRU and the gNB (via the RIS) may be established. The WTRU may receive an RRC configuration and / or enter an RRC connected state.

[0110] 8, certain downlink synchronization signals (e.g., SSB) and RMSI may be detected by the WTRU even when, for example, the WTRU is outside of gNB coverage (e.g., blocked by an obstacle) (e.g., as seen at 808). Even when the WTRU is within network coverage (e.g., no obstacles are present), with RIS assistance the WTRU may be able to detect the SSB and / or RMSI with better quality (e.g., because the RIS may boost the signal).

[0111] RIS-assisted SSB transmission and / or detection may be performed (e.g., at 802). For example, the gNB / TRP may transmit SSB / PBCH and / or RMSI candidates to the RIS. If the WTRU is within gNB / TRP coverage, the WTRU may synchronize with the SSB transmitted from the gNB / TRP, for example, without the assistance of the RIS (e.g., for backward compatibility reasons). The WTRU may perform a P1 procedure, for example, based on the SSB received from the gNB. If the RIS configuration is different at the transmission timings of different SSB transmissions, the P1 procedure may be affected (e.g., adversely affected). For example, the WTRU may receive an SSB (e.g., ID#2) from the gNB at the transmission timing of the first SSB transmission. At the transmission timing of the next SSB transmission, the RIS may reflect the SSB (ID#2) differently, which may cause the WTRU Rx beam tuning to be different (e.g., different from the transmission timing of the previous SSB transmission).

[0112] One or more of the following can be used to support backward compatibility for certain initial access procedures (e.g., NR legacy WTRU with RIS-assisted initial access). The RIS can be maintained in (e.g., one) predefined spatial state (e.g., a spatial direction with a specific beamwidth, which can be controlled and configured by the RIS controller) during SSB transmission timing (e.g., candidate SSB index / location). The RIS configuration can be the same for SSB transmission timing, so that no dynamic configuration is required, e.g., to reflect an incoming SSB. Some SSB indices can be equal to legacy values ​​(e.g., A, B, C, D, E, F, and G as shown in Table 1). That is, legacy SSB transmission patterns can be maintained.

[0113] 9-13 are diagrams illustrating embodiments related to RIS-added initial access and / or backward compatibility. As seen in FIG. 9, such implementations may be applied to WTRUs that are out of gNB / TRP coverage (e.g., without RIS assistance), as shown, for example, by WTRU1 902a and WTRU2 902b. The WTRUs may assume that SSBs are transmitted according to a certain pattern (e.g., a pattern used in NR). Referring again to FIG. 9, WTRU1 902a and WTRU2 902b may be assisted by RIS#1 904a, and WTRU3 902c may be able to receive links 908a from both the gNB / TRP 906 and RIS#2 904b. WTRU3 902c shown in FIG. 9 may detect different SSBs (e.g., SSB#2 908b and SSB#3 908c shown in FIG. 9) at various SSB transmission timings (e.g., candidate SSB indices and / or locations). For example, the SSBs (e.g., beams) of an SSB burst set may be time division multiplexed (TDM).

[0114] One or more (e.g., multiple) SSBs 908a-c may be forwarded to one or more (e.g., multiple) RISs 904a-b, either non-collocated (e.g., as shown in FIG. 9) or collocated (e.g., as shown in FIG. 11). Now, referring to FIG. 11, WTRU1 1102a can detect SSB#1 1104a reflected by RIS#1 1106a at SSB transmission timing (e.g., candidate SSB index / position) x, and further, WTRU2 1102b can detect SSB#2 1104b reflected by RIS#2 1106b at SSB transmission timing y.

[0115] In a particular implementation (e.g., NR), the WTRU may assume that the transmission of an SSB (e.g., in a burst set) in a half frame starts from the first symbol of the first slot of the half frame. For the serving cell, the WTRU may assume that the periodicity is the same as the half frame periodicity for reception of the SSB and that the duration of the burst set is within the half frame. Additionally or alternatively, the number of SSB indices may be equal to the number of SSB transmission timings (e.g., candidate SSB indexes / positions) in the SSB burst set. If the number of SSB indices is equal to the number of SSB transmission timings of the SSB burst set, the WTRU may obtain timing and frequency synchronization information. In an embodiment, the WTRU may obtain timing and frequency synchronization information from the SSB index and / or the candidate SSB index (e.g., after the WTRU successfully detects an SSB in the SSB burst set). In an embodiment, the WTRU may obtain a cell ID from the PSS and / or the SSS. In an embodiment, the WTRU may decode the PBCH payload and / or fetch the SSB index.

[0116] The WTRU may obtain timing synchronization by mapping the SSB index and the candidate SSB index to determine the camping cell slot and / or frame timing without ambiguity. Additionally or alternatively, a quasi-colocation (QCL) assumption may be based on the QCL assumption of the gNB / TRP-to-RIS path, for example, because the reflected beam of the RIS-to-WTRU path may be associated with the beam of the gNB / TRP-to-RIS path in a one-to-one mapping relationship (e.g., as shown in FIG. 10).

[0117] As described herein, backward compatibility support for certain initial access procedures (e.g., NR legacy WTRUs with RIS-assisted initial access) may be provided. In certain implementations, support for RIS to perform, for example, SSB beam scanning (e.g., by using SSB repetition techniques) may be provided. One or more of the following may apply. For example, as described herein, the RIS may be maintained in a (e.g., one) given state (e.g., a predefined spatial state associated with a spatial direction and / or a particular beamwidth) during a given SSB transmission (e.g., transmission timing and / or candidate SSB index and / or location). The SSB transmission may be repeated one or more times (e.g., multiple times) at, for example, different transmission timings (e.g., candidate SSB index and / or location).

[0118] The RIS may determine (e.g., assume) that the (e.g., each) repeated SSB is associated with a similar (e.g., identical) quasi-colocation (QCL) assumption as the gNB-to-RIS path. For example, the QCL assumption may be valid for (e.g., only for) the gNB / TRP-to-RIS path. In a particular implementation, the RIS may not determine (e.g., assume) that the QCL for the SSB repetitions is the same, for example, because the RIS controller may configure repeated SSB transmissions (e.g., SSB transmissions in the same spatial direction on the gNB / TRP-to-RIS path) on various RIS-to-WTRU paths. However, in a particular implementation, the WTRU may determine (e.g., assume) that the QCL for the SSB repetitions is the same based on the detected SSB index (e.g., because the QCL source reference signal may be a detected SSB during initial access).

[0119] A network (e.g., a gNB) may configure a RIS controller with associated timing to reflect SSBs during the transmit timing of SSB transmissions. If the network configures the RIS with associated timing, repeated SSBs may be transmitted toward the same RIS (e.g., when the RIS is stationary). Furthermore, if the network configures the RIS with associated timing, the RIS controller may configure and / or control the RIS to reflect SSBs in one or more (e.g., different) spatial directions during the transmit timing of different SSB transmissions.

[0120] 12A and 12B illustrate examples relating to multiple SSB transmissions to a RIS using similar (e.g., the same) SSB indexes. As seen in FIG. 12A, SSB#1 1202a may be reflected in a spatial direction at SSB transmission timing x. As seen in FIG. 12B, SSB#1 1202b may be reflected in another spatial direction at another SSB transmission timing y. For example, if multiple SSBs 1202a-b are transmitted toward the same RIS 1204a-b, the multiple SSBs 1202a-b may be transmitted with similar (e.g., the same) SSB indexes (e.g., as illustrated in FIG. 12A and FIG. 12B). For example, the multiple SSB transmissions 1202a-b may be quasi co-located (QCLed) from the gNB / TRP 1206a-b to the RIS 1204a-b. As described herein, SSB 1202a-b repetition (e.g., as illustrated in Figures 12A and 12B) may refer to a situation in which the same SSB index is transmitted for multiple SSB transmission timings within an SSB burst set. The network may configure RIS controllers 1208a-b to set the RIS configuration, and the RIS controllers 1208a-b may configure RIS 1204a-b for repetitive SSB beams 1202a-b, for example, in different directions. In certain implementations, beam scanning may be performed from the RIS 1204a-b.

[0121] 13 illustrates one embodiment relating to a single SSB burst set 1302 with SSB repetitions where the SSBs are reflected by the RIS 1304. To support SSB repetitions, for example, as seen in FIG. 13, the number of transmitted SSB transmission timings 1306 (e.g., the number of candidate SSB indexes / positions) may be greater than the number of SSB indexes 1308. When the number of transmitted SSB transmission timings 1306 is greater than the number of SSB indexes 1308, repeated SSBs, or SSB bursts, within the same SSB burst set 1302 may be forwarded to the same RIS 1304.

[0122] In an embodiment, for a gNB / TRP-to-RIS path, the QCL assumption may be valid for repeated SSBs toward the same RIS, but for a RIS-to-WTRU path, the Rx beam of the WTRU may not be the same (e.g., if the RIS controller configures the RIS to perform SSB beam scanning). For example, the RIS may switch SSB beams to different spatial directions at different candidate SSB indices (e.g., as illustrated in Figures 12A and 12B).

[0123] In an embodiment, the parameter

[0124]

number

[0125]

number

[0126]

number

[0127]

number

[0128] Table 2 shows the candidate SSB index, SSB index, and

[0129]

number

[0130]

number

[0131]

number

[0132]

number

[0133]

number

[0134] [Table 2]

[0135] If the WTRU detects the SSB during initial access, the receive paths from the gNB / TRP-to-WTRU and / or the RIS-to-WTRU may be transparent to the WTRU. In certain implementations, the RIS may be proximate (e.g., closely located) to the WTRU. If proximate to the RIS, the WTRU may be able to detect the SSB via the RIS (e.g., with better receive power). However, in such embodiments, the effective propagation delay may be increased. For example, the effective propagation delay may be equal to the propagation delay associated with the gNB / TRP-to-RIS path plus the propagation delay associated with the RIS-to-WTRU path.

[0136] In a particular implementation, the candidate SSB index may be used in determining when a detected SSB is received via a RIS or from a gNB / TRP (e.g., via a gNB / TRP-to-WTRU path). For example, the WTRU may perform a test (e.g., hypothesis testing) to determine whether the detected SSB is received from a RIS or from a gNB. For example, we may determine that a detected candidate SSB index is

[0137]

number

[0138]

number

[0139]

number

[0140]

number

[0141]

number

[0142]

number

[0143] Referring to FIG. 13, the SSB index (e.g.,

[0144]

number

[0145]

number

[0146] If the WTRU determines that the detected SSB is received via the RIS-to-WTRU path, the WTRU may continue with the QCL assumption for the gNB / TRP-to-RIS path (e.g., for the PDCCH in the CORESET#0 search space (SS) indicated by the PBCH payload and / or for the PDSCH for SI / RMSI scheduled by the PDCCH in the CORESET#0 search space). Regardless of the CORESET#0 multiplexing pattern (e.g., TDM, FDM, hybrid, etc.), the QCL assumption may be valid, for example, because the source reference signal is the SSB detected at the SSB transmission timing during initial access.

[0147] FIG. 14 is a diagram illustrating an example procedure 1400 related to determining the source of a detected SSB (e.g., via the RIS-to-WTRU path or the gNB-to-WTRU). At 1402, the WTRU may determine whether it has detected an SSB (e.g., an SSB transmission). If the WTRU does not detect the SSB, the WTRU continues monitoring for the SSB. However, if the WTRU does detect the SSB, at 1406, the WTRU may determine whether the SSB is a candidate SSB index.

[0148]

number

[0149]

number

[0150]

number

[0151]

number

[0152]

number

[0153] 1406, candidate SSB index

[0154]

number

[0155]

number

[0156]

number

[0157]

number

[0158] After the WTRU determines whether the SSB transmission was sent via the RIS-to-WTRU path at 1412 or via the gNB / TRP-to-WTRU path at 1414, the WTRU may obtain a CORESET#0 indication from the PBCH payload of the SSB transmission at 1416. At 1418, the WTRU may determine whether there is a PDSCH scheduled for the SI at 1418. If the WTRU determines at 1418 that there is a PDSCH scheduled for the SI, then at 1420, the WTRU may retrieve the SI for the PRACH resource configuration and / or RACH transmission timing.

[0159] FIG. 15 is a diagram illustrating an embodiment related to RIS-assisted SSB transmission. One or more of the following may be applied. In an embodiment, at 1502, the gNB / TRP may configure the RIS controller (e.g., to control the RIS) prior to SSB transmission. For example, the gNB configuration may include K different RIS configurations. For example, the RIS controller may configure the RIS for recurring SSB beams at various times (e.g., candidate SSB indexes) with different configurations. At 1504, the RIS controller may apply configuration #1 for SSB#1 generated at transmit timing #0. For example, at 1506, configuration #1 may reflect SSB#1 in a certain spatial direction. At 1508, SSB#1 may be transmitted again, for example, at the next transmit timing, in which case a different RIS configuration is applied by the RIS at 1510, which causes SSB#1 to be reflected in a different spatial direction at 1512. The configurations can be applied in this manner until all K RIS configurations have been processed (as shown at 1514).

[0160] RIS-assisted SSB detection can be performed. One or more of the following may be applied: Figures 16A and 16B illustrate examples of multiple SSBs 1602a-b associated with different SSB indices that may be transmitted towards the RIS 1604a-b. With reference to the example illustrated in Figure 16A, SSB#1 1602a may be reflected in one spatial direction at SSB transmission timing x of 1606a. With reference to the example illustrated in Figure 16B, SSB#2 1602b may be reflected in another spatial direction at another SSB transmission timing y of 1606b.

[0161] The gNB may, for example, transmit redundant SSB bursts in the same SSB burst set, which allows the RIS to perform SSB beam switching. One or more (e.g., multiple) SSBs with different SSB indices may be transmitted towards the same RIS. As described herein, the RIS may be configured with (e.g., one) predefined spatial state (e.g., a spatial direction with a particular beamwidth) for a given SSB transmission timing (e.g., candidate SSB index / location). For example, candidate SSB index

[0162]

number

[0163]

number

[0164] 16A and 16B, one or more (e.g., multiple) SSBs associated with different SSB indices (e.g., #1 1602a and #2 1602b) and transmit timings may be transmitted toward the same RIS 1604a-b. In such an implementation, the RIS controllers 1610a-b may configure the RISs 1604a-b to reflect (e.g., or beamform) an incoming SSB at the corresponding SSB transmit timings.

[0165] In a particular implementation, the candidate SSB indices of the SSB burst set

[0166]

number

[0167]

number

[0168] 17 illustrates an embodiment relating to a single SSB burst set 1702 that includes an extra SSB burst. As can be seen in FIG. 17, the candidate SSB indices

[0169]

number

[0170] The WTRU may determine the source of the detected SSB (e.g., RIS-to-WTRU path, gNB / TRP-to-WTRU path, direct path, etc.) based on the candidate SSB index or SSB indexes 1706a-e of the SSB transmission. For example, the SSB indexes 1706a-e may be equal to the candidate SSB indexes. For example, the WTRU may determine the source of the detected SSB (e.g., RIS-to-WTRU path, gNB / TRP-to-WTRU path, direct path, etc.) based on the candidate SSB index or SSB indexes of the SSB transmissions.

[0171]

number

[0172]

number

[0173] FIG. 18 illustrates an embodiment related to SSB burst transmission to a RIS. One or more of the following may be applied. In an embodiment, at 1802, the gNB / TRP may configure the RIS controller (e.g., to control the RIS) prior to an SSB transmission. For example, the gNB configuration may include K different RIS configurations. For example, the RIS controller may apply a RIS configuration for each SSB (e.g., SSB#1, SSB#2) with different configurations. At 1804, the RIS controller may apply configuration #i1 (e.g., configuration instructions in a time entity) for SSB#1 occurring at transmission timing #0. For example, at 1806, configuration #i1 may reflect SSB#1 in one spatial direction. At 1808, at the next transmission timing, SSB#2 may be transmitted (e.g., again). For example, at 1810, a different RIS configuration may be applied for SSB#2. For example, at 1812, a different RIS configuration may be applied such that the RIS reflects SSB#2 in a different spatial direction. Configurations can be applied in this manner (as shown at 1814) until all K RIS configurations have been processed.

[0174] RIS-aware SSB detection can be performed. One or more of the following may apply: FIG. 19 illustrates an example embodiment associated with multiple SSB burst sets 1902a-b. With reference to the example embodiment illustrated in FIG. 19, a first SSB burst set 1902a may be associated with an implementation that does not include a RIS (e.g., a legacy WTRU) and a second SSB burst set 1902b may be associated with an implementation that includes a RIS 1908. The gNB may transmit redundant SSB burst sets toward a RIS that may be configured to reflect SSBs. For example, the redundant SSB burst sets may be used by the RIS to perform SSB beam scanning. Additionally or alternatively, each periodicity of the SSB burst sets may be dependent on or independent of other SSB burst sets. In a particular implementation, the RIS controller may configure the RIS to reflect SSBs in a given spatial condition (e.g., a spatial direction with a particular beamwidth) during an SSB transmission timing (e.g., a candidate SSB index / location). Candidate SSBs or SSBs in the same SSB burst set (e.g., within a half frame) are, e.g.,

[0175]

number

[0176]

number

[0177] Each SSB burst may be associated with its own candidate SSB index and SSB burst set index. For example, the PBCH and / or DM-RS (e.g., MIB) of the PBCH payload may indicate an associated candidate SSB index 1910 and / or SSB burst set index for an SSB burst. In such an implementation, the WTRU may simultaneously, or substantially simultaneously, detect SSBs via the gNB / TRP-to-WTRU path and / or via the RIS-to-WTRU path. The WTRU may use the SSB burst set index and / or the candidate SSB index to identify the SSB symbol location, e.g., such that there is no ambiguity related to timing synchronization information. For example, the WTRU may determine the source of the detected SSB (e.g., via the RIS-to-WTRU path and / or the gNB / TRP-to-WTRU direct path) based on the candidate SSB index and / or the burst set index. For example, if the WTRU detects an SSB with an SSB transmission timing not associated with burst set 1, the WTRU may determine that the detected SSB was received via the RIS-to-WTRU path. If the WTRU detects an SSB with an SSB transmission timing attached to burst set 1, the WTRU may determine that the detected SSB was received via the gNB / TRP-to-WTRU direct path.

[0178] As seen in FIG. 19, two SSB burst sets may be used 1902a-b. The starting symbols of the candidate SSB indices may include {4,8,16,20}+28·n, n=0,1 for the first burst set, and {4,8,16,20}+28·n=3,4 for the second burst set, respectively. If the WTRU detects an SSB at the starting symbol of 76=16+3·28, the WTRU may determine that the detected SSB was received via the RIS-to-WTRU path. The WTU may determine timing synchronization information using the detected candidate SSB index and / or the burst set index. For example, the second burst set 1902b may not be transmitted within a half frame. For example, if the burst set index is known by the WTRU upon detection of an SSB in the burst set, the timing synchronization information may be known by the WTRU.

[0179] Referring again to the embodiment illustrated in Figure 19, SSB burst set 1 1902a may be associated with an offset from SSB burst set 2 1902b. If the offset 1910 between SSB burst set 1 1902a and SSB burst set 2 1902b is set to 0, then SSB burst set 1 1902a and SSB burst set 2 1902b may be adjacent and / or contiguous in time. The offset 1910 of the redundant (e.g., second) burst set may be configured by higher layers and / or based on a predefined specification.

[0180] RIS-assisted RACH transmission can be performed. One or more of the following may apply: FIG. 20 illustrates an embodiment related to separated ROs for multiple SSB burst sets 2002a-b. In a particular implementation (e.g., NR), a parameter such as ssb-perRACHOccasionAndCB-PreamblesPerSSB may specify the number of SSBs (e.g., SSB index) that can be mapped to the PRACH transmission timing (RO) and / or the number of preamble indexes (e.g., SSB index) that can be mapped to the SSBs. If SSB indexes (e.g., the same SSB index) are used in various spatial directions and / or are mapped to the same RO and / or preamble, one or more ambiguities may exist (e.g., with respect to legacy SSB indexes that are mapped to ROs and / or preambles). For example, the RIS may use repeated SSBs with the same SSB index (e.g., to perform beam scanning). In certain implementations, if repeated SSBs are mapped to the same RO and / or preamble, the network may not be able to distinguish between SSBs transmitted at different SSB transmission timings that are detected by the WTRU.

[0181] However, in certain implementations, the candidate SSB indexes can be used for purposes of SSB to RO and / or preamble mapping for licensed bands using the RIS (e.g., instead of using the SSB index for SSB to RO and / or preamble mapping). As seen in Table 2, the total number of candidate SSB indexes

[0182]

number

[0183] In a particular implementation, the ROs 2004a-b for the various SSB burst sets 2002a-b may be separated. For example, the ROs 2004a-b may be separated based on network configuration (e.g., SIB / RMSI). The number (e.g., total number) of candidate SSB indices may be equal to the total number of SSBs in each SSB burst set 2002a-b. SSBs with the same index may be mapped to different ROs 2004a-b, which may reduce the likelihood of ambiguity.

[0184] As described herein, the candidate SSB index may be greater than the SSB index. The excess candidate SSB index may be used for SSB index repetitions toward a RIS (e.g., the same RIS). In such a case, the RIS controller may apply a configuration to reflect the respective SSB based on the candidate SSB index. The WTRU may determine the source of the reflected SSB (e.g., via the RIS-to-WTRU path and / or the gNB / TRP-to-WTRU path), for example, based on the detected candidate SSB index and / or the SSB index. Additionally or alternatively, the candidate SSB index may be used for mapping associated with the PRACH transmission timing and preamble.

[0185] As described herein, multiple SSB indices may be transmitted toward a RIS (e.g., the same RIS), and the RIS controller may apply an associated configuration, e.g., based on the candidate SSB index, to reflect the SSB. For example, the SSB index may be used for mapping associated with the PRACH transmission timing and the preamble.

[0186] As described herein, the SSB burst set may be broadcast (e.g., by the gNB / TRP). One or more of the SSB burst sets may be used by the RIS (e.g., to perform beam scanning). The RIS may use redundant burst sets. The RIS controller may apply associated configurations to reflect SSBs based on the candidate SSB index and / or the SSB index (e.g., with a dedicated SSB burst set). The RO may be isolated. For example, RO isolation may be configured for the WTRU (e.g., by the network). The WTRU may transmit a PRACH on a dedicated RO based on, for example, a detected SSB index associated with a burst set index.

Claims

1. 1. A method implemented by a wireless transmit / receive unit (WTRU), the method comprising: Detecting a reflected synchronization signal block (SSB) transmission from a reconfigurable intelligent surface (RIS), the reflected SSB being associated with an index; determining that the reflected SSB transmission was reflected by the RIS based on the index associated with the reflected SSB transmission; and performing a random access procedure with a network device via the RIS based on the index.

2. The method of claim 1 , wherein the index associated with the reflected SSB is an SSB index or a candidate SSB index.

3. 2. The method of claim 1, wherein determining that the reflected SSB transmission has been reflected by the RIS comprises determining that the index associated with the SSB transmission is not quasi-collocated (QCL) with a candidate SSB index associated with the SSB transmission.

4. the index associated with the reflected SSB is a candidate SSB index; 2. The method of claim 1, wherein determining that the reflected SSB transmission has been reflected by the RIS comprises determining that the index associated with the SSB transmission is not quasi-collocated (QCL) with a burst set index associated with the SSB transmission.

5. 2. The method of claim 1, wherein the reflected SSB transmission is associated with an SSB burst transmission that includes a plurality of SSB transmissions, each of the plurality of SSB transmissions being associated with a respective index.

6. The method of claim 5 , wherein the plurality of SSB transmissions includes SSB transmissions that are reflected by the RIS and SSB transmissions that are not reflected by the RIS.

7. The method of claim 5 , wherein the spatial state of the RIS is maintained constant during the SSB burst transmission.

8. 8. The method of claim 7, wherein the SSB burst transmission includes the reflected SSB transmission and a plurality of legacy SSB transmissions, the plurality of legacy SSB transmissions are not reflected by the RIS, and the SSB burst transmission is transmitted according to a legacy SSB transmission pattern.

9. The method of claim 5 , wherein at least a subset of the plurality of SSB transmissions of the SSB burst transmission are reflected by the RIS at a plurality of different spatial states.

10. Furthermore, 2. The method of claim 1, comprising detecting a second reflected SSB transmission from the reflected RIS, the second reflected SSB transmission being associated with a different spatial beam than the reflected SSB transmission, the reflected SSB transmission being associated with a first SSB transmission burst from the network device, the second reflected SSB transmission being associated with a second SSB burst transmission from the network device, the second reflected SSB transmission being associated with a same index as the reflected SSB transmission, and a number of candidate SSB indexes being greater than a number of SSB indexes.

11. 1. A wireless transmission and reception device comprising: a processor; and a memory, the processor comprising: Detecting a reflected synchronization signal block (SSB) transmission from a reconfigurable intelligent surface (RIS), the reflected SSB being associated with an index; determining that the reflected SSB transmission was reflected by the RIS based on the index associated with the reflected SSB transmission; and performing a random access procedure with a network device via the RIS based on the index.

12. The WTRU of claim 11 , wherein the index associated with the reflected SSB is an SSB index or a candidate SSB index.

13. 12. The WTRU of claim 11, wherein determining that the reflected SSB transmission has been reflected by the RIS includes determining that the index associated with the SSB transmission is not quasi collocated (QCL) with a candidate SSB index associated with the SSB transmission.

14. the index associated with the reflected SSB is a candidate SSB index; 12. The WTRU of claim 11, wherein determining that the reflected SSB transmission has been reflected by the RIS includes determining that the index associated with the SSB transmission is not quasi-co-located (QCL) with a burst set index associated with the SSB transmission.

15. 12. The WTRU of claim 11, wherein the reflected SSB transmission is associated with an SSB burst transmission that includes a plurality of SSB transmissions, each of the plurality of SSB transmissions being associated with a respective index.

16. The WTRU of claim 15, wherein the plurality of SSB transmissions include SSB transmissions that are reflected by the RIS and SSB transmissions that are not reflected by the RIS.

17. The WTRU of claim 15, wherein the spatial state of the RIS is maintained constant during the SSB burst transmission.

18. 20. The WTRU of claim 17, wherein the SSB burst transmission includes the reflected SSB transmission and a plurality of legacy SSB transmissions, the plurality of legacy SSB transmissions are not reflected by the RIS, and the SSB burst transmission is transmitted according to a legacy SSB transmission pattern.

19. The WTRU of claim 15, wherein at least a subset of the plurality of SSB transmissions of the SSB burst transmission are reflected by the RIS in a plurality of different spatial states.

20. The processor, and detecting a second reflected SSB transmission from the reflected RIS, the second reflected SSB transmission being associated with a different spatial beam than the reflected SSB transmission, the reflected SSB transmission being associated with a first SSB transmission burst from the network device, and the second reflected SSB transmission being associated with a second SSB burst transmission from the network device; The WTRU of claim 11 , wherein the second reflected SSB transmission is associated with a same index as the reflected SSB transmission, and a number of candidate SSB indexes is greater than a number of SSB indexes.

Images