WO2025151688A1

WO2025151688A1 - Methods, architectures, apparatuses and systems for multiplexed backscattering

Info

Publication number: WO2025151688A1
Application number: PCT/US2025/011020
Authority: WO
Inventors: Fumihiro Hasegawa; Erdem Bala; Martino Freda; Paul Marinier; Moon Il Lee; Jongwoo HONG
Original assignee: InterDigital Patent Holdings Inc
Current assignee: InterDigital Patent Holdings Inc
Priority date: 2024-01-10
Filing date: 2025-01-10
Publication date: 2025-07-17
Anticipated expiration: 2026-07-10

Abstract

Methods, architectures, apparatuses, and systems directed to multiplexed backscattering are described herein. In an embodiment, a transmit/receive unit (WTRU) may receive first information indicating a first time offset with respect to a first reference signal transmission. The WTRU may receive the first reference signal transmission and a second reference signal transmission. The WTRU may transmit a third reference signal transmission based on the received second reference signal transmission at the indicated first time offset with respect to a first reference signal transmission, the third reference signal transmission being transmitted responsive to a power condition being satisfied.

Description

METHODS, ARCHITECTURES, APPARATUSES AND SYSTEMS FOR MULTIPLEXED B ACKSCATTERING

CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims the benefit of US Patent Application No. 63/619,619 filed January

10, 2024, which is incorporated herein by reference in its entirety.

TECHNICAL FIELD

[0002] The present disclosure is generally directed to the fields of communications, software and encoding, including methods, architectures, apparatuses, and systems directed to multiplexed backscattering.

BACKGROUND

[0003] In the third generation partnership project (3 GPP) Release 16, downlink, uplink and downlink and uplink positioning methods may be used. In 3 GPP, devices such as ambient Internet of Things (loT) devices may transmit by backscattering and may create collisions at the base station. Embodiments described herein have been designed with the foregoing in mind.

SUMMARY

[0004] Methods, architectures, apparatuses, and systems directed to multiplexed backscattering are described herein. In an embodiment, a method implemented in a wireless transmit/receive unit (WTRU) is described. The method may include receiving first information indicating a first time offset with respect to a first reference signal transmission. The method may include receiving the first reference signal transmission and e.g., determining whether the received first reference signal transmission may satisfy a power condition. The method may include receiving a second reference signal transmission and transmitting a third reference signal transmission based on (1) the received second reference signal transmission, (2) the indicated first time offset, and (3) whether the received first reference signal transmission may satisfy the power condition. In an example, the third reference signal transmission may be transmitted based on the received second reference signal transmission at the indicated first time offset with respect to the first reference signal transmission. In various embodiments, the third reference signal transmission may be transmitted responsive to a power condition being satisfied.

[0005] In an embodiment, a WTRU including a circuitry, including any of a transmitter, a receiver, a processor, and a memory is described. The WTRU may be configured to receive first information indicating a first time offset with respect to a first reference signal transmission. The WTRU may be configured to receive the first reference signal transmission and e.g., to determine whether the received first reference signal transmission may satisfy a power condition. The WTRU may be configured to receive a second reference signal transmission and to transmit a third reference signal transmission based on (1) the received second reference signal transmission, (2) the indicated first time offset, and (3) whether the received first reference signal transmission may satisfy the power condition. In an example, the third reference signal transmission may be transmitted based on the received second reference signal transmission at the indicated first time offset with respect to the first reference signal transmission. In various embodiments, the third reference signal transmission may be transmitted responsive to a power condition being satisfied. [0006] In an embodiment, a method implemented in a network element is described. The method may include transmitting first information to a first WTRU. In various embodiments, the first information may indicate a first time offset with respect to a first reference signal transmission of a plurality of reference signal transmissions. The method may include transmitting second information to a second WTRU. In various embodiments, the second information may indicate a second time offset with respect to the first reference signal transmission, and the first time offset may be different from the second time offset. The method may include transmitting the plurality of reference signal transmissions. The method may include receiving from the first WTRU, a second reference signal transmission at the first time offset with respect to the first reference signal transmission and receiving from the second WTRU, a third reference signal transmission at the second time offset with respect to the first reference signal transmission.

[0007] In an embodiment, a network element including a circuitry, including any of a transmitter, a receiver, a processor, and a memory is described. The network element may be configured to transmit first information to a first WTRU. In various embodiments, the first information may indicate a first time offset with respect to a first reference signal transmission of a plurality of reference signal transmissions. The network element may be configured to transmit second information to a second WTRU. In various embodiments, the second information may indicate a second time offset with respect to the first reference signal transmission, and the first time offset may be different from the second time offset. The network element may be configured to transmit the plurality of reference signal transmissions. The network element may be configured to receive from the first WTRU, a second reference signal transmission at the first time offset with respect to the first reference signal transmission and to receive from the second WTRU, a third reference signal transmission at the second time offset with respect to the first reference signal transmission.

BRIEF DESCRIPTION OF THE DRAWINGS

[0008] A more detailed understanding may be had from the detailed description below, given by way of example in conjunction with drawings appended hereto. Figures in such drawings, like the detailed description, are examples. As such, the Figures (FIGs.) and the detailed description are not to be considered limiting, and other equally effective examples are possible and likely. Furthermore, like reference numerals ("ref.") in the FIGs. indicate like elements, and wherein: [0009] FIG. 1 A is a system diagram illustrating an example communications system;

[0010] FIG. IB is a system diagram illustrating an example wireless transmit/receive unit (WTRU) that may be used within the communications system illustrated in FIG. 1 A;

[0011] FIG. 1C is a system diagram illustrating an example radio access network (RAN) and an example core network (CN) that may be used within the communications system illustrated in FIG. 1A;

[0012] FIG. ID is a system diagram illustrating a further example RAN and a further example CN that may be used within the communications system illustrated in FIG. 1 A;

[0013] FIG. 2 is a diagram illustrating an example positioning reference signal (PRS) transmission;

[0014] FIG. 3 is a diagram illustrating an example transmission timeline of a transmit and receive point (TRP);

[0015] FIG. 4 is a diagram illustrating an example timeline for transmission of a reference PRS and a measurement PRS;

[0016] FIG. 5 is a diagram illustrating another example timeline for transmission of a reference PRS and a measurement PRS;

[0017] FIG. 6 is a diagram illustrating an example timeline;

[0018] FIG. 7 is diagram illustrating an example signaling from the network;

[0019] FIG. 8 is a diagram illustrating an example timeline for transmission of PRS from the network;

[0020] FIG. 9 is a diagram illustrating an example of more than one message arranged in a time division multiplex manner;

[0021] FIG. 10 is a diagram illustrating an example of more than one message arranged in a frequency division multiplex manner;

[0022] FIG. 11 is a diagram illustrating an example protocol exchange between the WTRU and the network;

[0023] FIG. 12 is a diagram illustrating an example timeline for transmission of a reference PRS and a measurement PRS;

[0024] FIG. 13 is a diagram illustrating an example timeline showing a timing offset;

[0025] FIG. 14 is a diagram illustrating an example slot structure for the WTRU;

[0026] FIG. 15 is a diagram illustrating an example of WTRU Tx muting pattern;

[0027] FIG. 16 is a diagram illustrating an example of WTRU Tx muting pattern with a granularity of repetitions: [0028] FIG. 17 is a diagram illustrating an example of WTRU Tx muting pattern with a granularity of repetition group;

[0029] FIG. 18 is a diagram illustrating an example of WTRU Tx muting pattern with a granularity of repetition group and with a transmission of a reference PRS;

[0030] FIG. 19 is a diagram illustrating an example of configured transmission filters for a WTRU;

[0031] FIG. 20 is a diagram illustrating an example of frequency domain multiplexing (FDM) based backscattering;

[0032] FIG. 21 is a diagram illustrating an example configuration of timing offset and hopping pattern;

[0033] FIG. 22 is a diagram illustrating an example of backscattering with frequency hopping and time shift;

[0034] FIG. 23 is a diagram illustrating an example method for multiplexed backscattering, implemented in a WTRU;

[0035] FIG. 24 is a diagram illustrating another example method for multiplexed backscattering, implemented in a WTRU;

[0036] FIG. 25 is a diagram illustrating an example method for multiplexed backscattering, implemented in a network element;

[0037] FIG. 26 is a diagram illustrating an example method for backscattering in presence of multipath, implemented in a WTRU; and

[0038] FIG. 27 is a diagram illustrating an example method for backscattering in presence of multipath, implemented in a network element.

DETAILED DESCRIPTION

[0039] In the following detailed description, numerous specific details are set forth to provide a thorough understanding of embodiments and/or examples disclosed herein. However, it will be understood that such embodiments and examples may be practiced without some or all of the specific details set forth herein. In other instances, well-known methods, procedures, components and circuits have not been described in detail, so as not to obscure the following description. Further, embodiments and examples not specifically described herein may be practiced in lieu of, or in combination with, the embodiments and other examples described, disclosed or otherwise provided explicitly, implicitly and/or inherently (collectively "provided") herein. Although various embodiments are described and/or claimed herein in which an apparatus, system, device, etc. and/or any element thereof carries out an operation, process, algorithm, function, etc. and/or any portion thereof, it is to be understood that any embodiments described and/or claimed herein assume that any apparatus, system, device, etc. and/or any element thereof is configured to carry out any operation, process, algorithm, function, etc. and/or any portion thereof.

[0040] Example Communications System

[0041] The methods, apparatuses and systems provided herein are well-suited for communications involving both wired and wireless networks. An overview of various types of wireless devices and infrastructure is provided with respect to FIGs. 1A-1D, where various elements of the network may utilize, perform, be arranged in accordance with and/or be adapted and/or configured for the methods, apparatuses and systems provided herein.

[0042] FIG. 1A is a system diagram illustrating an example communications system 100 in which one or more disclosed embodiments may be implemented. The communications system 100 may be a multiple access system that provides content, such as voice, data, video, messaging, broadcast, etc., to multiple wireless users. The communications system 100 may enable multiple wireless users to access such content through the sharing of system resources, including wireless bandwidth. For example, the communications systems 100 may employ one or more channel access methods, such as code division multiple access (CDMA), time division multiple access (TDMA), frequency division multiple access (FDMA), orthogonal FDMA (OFDMA), singlecarrier FDMA (SC-FDMA), zero-tail (ZT) unique-word (UW) discrete Fourier transform (DFT) spread OFDM (ZT UW DTS-s OFDM), unique word OFDM (UW-OFDM), resource block- filtered OFDM, filter bank multicarrier (FBMC), and the like.

[0043] As shown in FIG. 1A, the communications system 100 may include wireless transmit/receive units (WTRUs) 102a, 102b, 102c, 102d, a radio access network (RAN) 104/113, a core network (CN) 106/115, a public switched telephone network (PSTN) 108, the Internet 110, and other networks 112, though it will be appreciated that the disclosed embodiments contemplate any number of WTRUs, base stations, networks, and/or network elements. Each of the WTRUs 102a, 102b, 102c, 102d may be any type of device configured to operate and/or communicate in a wireless environment. By way of example, the WTRUs 102a, 102b, 102c, 102d, any of which may be referred to as a "station" and/or a "STA", may be configured to transmit and/or receive wireless signals and may include (or be) a user equipment (UE), a mobile station, a fixed or mobile subscriber unit, a subscription-based unit, a pager, a cellular telephone, a personal digital assistant (PDA), a smartphone, a laptop, a netbook, a personal computer, a wireless sensor, a hotspot or Mi- Fi device, an Internet of Things (loT) device, a watch or other wearable, a head-mounted display (HMD), a vehicle, a drone, a medical device and applications (e.g., remote surgery), an industrial device and applications (e.g., a robot and/or other wireless devices operating in an industrial and/or an automated processing chain contexts), a consumer electronics device, a device operating on commercial and/or industrial wireless networks, and the like. Any of the WTRUs 102a, 102b, 102c and 102d may be interchangeably referred to as a UE.

[0044] The communications systems 100 may also include a base station 114a and/or a base station 114b. Each of the base stations 114a, 114b may be any type of device configured to wirelessly interface with at least one of the WTRUs 102a, 102b, 102c, 102d, e.g., to facilitate access to one or more communication networks, such as the CN 106/115, the Internet 110, and/or the networks 112. By way of example, the base stations 114a, 114b may be any of a base transceiver station (BTS), a Node-B (NB), an eNode-B (eNB), a Home Node-B (HNB), a Home eNode-B (HeNB), a gNode-B (gNB), a new radio (NR) Node-B (NR NB), a site controller, an access point (AP), a wireless router, and the like. While the base stations 114a, 114b are each depicted as a single element, it will be appreciated that the base stations 114a, 114b may include any number of interconnected base stations and/or network elements.

[0045] The base station 114a may be part of the RAN 104/113, which may also include other base stations and/or network elements (not shown), such as a base station controller (BSC), a radio network controller (RNC), relay nodes, etc. The base station 114a and/or the base station 114b may be configured to transmit and/or receive wireless signals on one or more carrier frequencies, which may be referred to as a cell (not shown). These frequencies may be in licensed spectrum, unlicensed spectrum, or a combination of licensed and unlicensed spectrum. A cell may provide coverage for a wireless service to a specific geographical area that may be relatively fixed or that may change over time. The cell may further be divided into cell sectors. For example, the cell associated with the base station 114a may be divided into three sectors. Thus, in an embodiment, the base station 114a may include three transceivers, i.e., one for each sector of the cell. In an embodiment, the base station 114a may employ multiple-input multiple output (MIMO) technology and may utilize multiple transceivers for each or any sector of the cell. For example, beamforming may be used to transmit and/or receive signals in desired spatial directions.

[0046] The base stations 114a, 114b may communicate with one or more of the WTRUs 102a, 102b, 102c, 102d over an air interface 116, which may be any suitable wireless communication link (e.g., radio frequency (RF), microwave, centimeter wave, micrometer wave, infrared (IR), ultraviolet (UV), visible light, etc.). The air interface 116 may be established using any suitable radio access technology (RAT).

[0047] More specifically, as noted above, the communications system 100 may be a multiple access system and may employ one or more channel access schemes, such as CDMA, TDMA, FDMA, OFDMA, SC-FDMA, and the like. For example, the base station 114a in the RAN 104/113 and the WTRUs 102a, 102b, 102c may implement a radio technology such as Universal Mobile Telecommunications System (UMTS) Terrestrial Radio Access (UTRA), which may establish the air interface 116 using wideband CDMA (WCDMA). WCDMA may include communication protocols such as High-Speed Packet Access (HSPA) and/or Evolved HSPA (HSPA+). HSPA may include High-Speed Downlink Packet Access (HSDPA) and/or High-Speed Uplink Packet Access (HSUPA).

[0048] In an embodiment, the base station 114a and the WTRUs 102a, 102b, 102c may implement a radio technology such as Evolved UMTS Terrestrial Radio Access (E-UTRA), which may establish the air interface 116 using Long Term Evolution (LTE) and/or LTE- Advanced (LTE-A) and/or LTE-Advanced Pro (LTE-A Pro).

[0049] In an embodiment, the base station 114a and the WTRUs 102a, 102b, 102c may implement a radio technology such as NR Radio Access, which may establish the air interface 116 using New Radio (NR).

[0050] In an embodiment, the base station 114a and the WTRUs 102a, 102b, 102c may implement multiple radio access technologies. For example, the base station 114a and the WTRUs 102a, 102b, 102c may implement LTE radio access and NR radio access together, for instance using dual connectivity (DC) principles. Thus, the air interface utilized by WTRUs 102a, 102b, 102c may be characterized by multiple types of radio access technologies and/or transmissions sent to/from multiple types of base stations (e.g., an eNB and a gNB).

[0051] In an embodiment, the base station 114a and the WTRUs 102a, 102b, 102c may implement radio technologies such as IEEE 802.11 (i.e., Wireless Fidelity (Wi-Fi), IEEE 802.16 (i.e., Worldwide Interoperability for Microwave Access (WiMAX)), CDMA2000, CDMA2000 IX, CDMA2000 EV-DO, Interim Standard 2000 (IS-2000), Interim Standard 95 (IS-95), Interim Standard 856 (IS-856), Global System for Mobile communications (GSM), Enhanced Data rates for GSM Evolution (EDGE), GSM EDGE (GERAN), and the like.

[0052] The base station 114b in FIG. 1 A may be a wireless router, Home Node-B, Home eNode- B, or access point, for example, and may utilize any suitable RAT for facilitating wireless connectivity in a localized area, such as a place of business, a home, a vehicle, a campus, an industrial facility, an air corridor (e.g., for use by drones), a roadway, and the like. In an embodiment, the base station 114b and the WTRUs 102c, 102d may implement a radio technology such as IEEE 802.11 to establish a wireless local area network (WLAN). In an embodiment, the base station 114b and the WTRUs 102c, 102d may implement a radio technology such as IEEE 802.15 to establish a wireless personal area network (WPAN). In an 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 any of a small cell, picocell or femtocell. As shown in FIG. 1 A, the base station 114b may have a direct connection to the Internet 110. Thus, the base station 114b may not be required to access the Internet 110 via the CN 106/115. [0053] The RAN 104/113 may be in communication with the CN 106/115, which may be any type of network configured to provide voice, data, applications, and/or voice over internet protocol (VoIP) services to one or more of the WTRUs 102a, 102b, 102c, 102d. The data may have varying quality of service (QoS) requirements, such as differing throughput requirements, latency requirements, error tolerance requirements, reliability requirements, data throughput requirements, mobility requirements, and the like. The CN 106/115 may provide call control, billing services, mobile location-based services, pre-paid calling, Internet connectivity, video distribution, etc., and/or perform high-level security functions, such as user authentication. Although not shown in FIG. 1 A, it will be appreciated that the RAN 104/113 and/or the CN 106/115 may be in direct or indirect communication with other RANs that employ the same RAT as the RAN 104/113 or a different RAT. For example, in addition to being connected to the RAN 104/113, which may be utilizing an NR radio technology, the CN 106/115 may also be in communication with another RAN (not shown) employing any of a GSM, UMTS, CDMA 2000, WiMAX, E-UTRA, or Wi-Fi radio technology.

[0054] The CN 106/115 may also serve as a gateway for the WTRUs 102a, 102b, 102c, 102d to access the PSTN 108, the Internet 110, and/or other networks 112. The PSTN 108 may include circuit-switched telephone networks that provide plain old telephone service (POTS). The Internet 110 may include a global system of interconnected computer networks and devices that use common communication protocols, such as the transmission control protocol (TCP), user datagram protocol (UDP) and/or the internet protocol (IP) in the TCP/IP internet protocol suite. The networks 112 may include wired and/or wireless communications networks owned and/or operated by other service providers. For example, the networks 112 may include another CN connected to one or more RANs, which may employ the same RAT as the RAN 104/114 or a different RAT.

[0055] Some or all of the WTRUs 102a, 102b, 102c, 102d in the communications system 100 may include multi-mode capabilities (e.g., the WTRUs 102a, 102b, 102c, 102d may include multiple transceivers for communicating with different wireless networks over different wireless links). For example, the WTRU 102c shown in FIG. 1A may be configured to communicate with the base station 114a, which may employ a cellular-based radio technology, and with the base station 114b, which may employ an IEEE 802 radio technology.

[0056] FIG. IB is a system diagram illustrating an example WTRU 102. As shown in FIG. IB, the WTRU 102 may include a processor 118, a transceiver 120, a transmit/receive element 122, a speaker/microphone 124, a keypad 126, a display/touchpad 128, non-removable memory 130, removable memory 132, a power source 134, a global positioning system (GPS) chipset 136, and/or other elements/peripherals 138, among others. It will be appreciated that the WTRU 102 may include any sub-combination of the foregoing elements while remaining consistent with an embodiment.

[0057] The processor 118 may be a general-purpose processor, a special purpose processor, a conventional processor, a digital signal processor (DSP), a plurality of microprocessors, one or more microprocessors in association with a DSP core, a controller, a microcontroller, Application Specific Integrated Circuits (ASICs), Field Programmable Gate Arrays (FPGAs) circuits, any other type of integrated circuit (IC), a state machine, and the like. The processor 118 may perform signal coding, data processing, power control, input/output processing, and/or any other functionality that enables the WTRU 102 to operate in a wireless environment. The processor 118 may be coupled to the transceiver 120, which may be coupled to the transmit/receive element 122. While FIG. IB depicts the processor 118 and the transceiver 120 as separate components, it will be appreciated that the processor 118 and the transceiver 120 may be integrated together, e.g., in an electronic package or chip.

[0058] The transmit/receive element 122 may be configured to transmit signals to, or receive signals from, a base station (e.g., the base station 114a) over the air interface 116. For example, in an embodiment, the transmit/receive element 122 may be an antenna configured to transmit and/or receive RF signals. In an embodiment, the transmit/receive element 122 may be an emitter/detector configured to transmit and/or receive IR, UV, or visible light signals, for example. In an 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.

[0059] Although the transmit/receive element 122 is depicted in FIG. IB as a single element, the WTRU 102 may include any number of transmit/receive elements 122. For example, the WTRU 102 may employ MIMO technology. Thus, in an 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.

[0060] The transceiver 120 may be configured to modulate the signals that are to be transmitted by the transmit/receive element 122 and to demodulate the signals that are received by the transmit/receive element 122. As noted above, the WTRU 102 may have multi-mode capabilities. Thus, the transceiver 120 may include multiple transceivers for enabling the WTRU 102 to communicate via multiple RATs, such as NR and IEEE 802.11, for example.

[0061] The processor 118 of the WTRU 102 may be coupled to, and may receive user input data from, the speaker/microphone 124, the keypad 126, and/or the display/touchpad 128 (e.g., a liquid crystal display (LCD) display unit or organic light-emitting diode (OLED) display unit). The processor 118 may also output user data to the speaker/microphone 124, the keypad 126, and/or the display/touchpad 128. In addition, the processor 118 may access information from, and store data in, any type of suitable memory, such as the non-removable memory 130 and/or the removable memory 132. The non-removable memory 130 may include random-access memory (RAM), readonly memory (ROM), a hard disk, or any other type of memory storage device. The removable memory 132 may include a subscriber identity module (SIM) card, a memory stick, a secure digital (SD) memory card, and the like. In other embodiments, the processor 118 may access information from, and store data in, memory that is not physically located on the WTRU 102, such as on a server or a home computer (not shown).

[0062] The processor 118 may receive power from the power source 134 and may be configured to distribute and/or control the power to the other components in the WTRU 102. The power source 134 may be any suitable device for powering the WTRU 102. For example, the power source 134 may include one or more dry cell batteries (e.g., nickel-cadmium (NiCd), nickel-zinc (NiZn), nickel metal hydride (NiMH), lithium-ion (Li-ion), etc.), solar cells, fuel cells, and the like.

[0063] The processor 118 may also be coupled to the GPS chipset 136, which may be configured to provide location information (e.g., longitude and latitude) regarding the current location of the WTRU 102. In addition to, or in lieu of, the information from the GPS chipset 136, the WTRU 102 may receive location information over the air interface 116 from a base station (e.g., base stations 114a, 114b) and/or determine its location based on the timing of the signals being received from two or more nearby base stations. It will be appreciated that the WTRU 102 may acquire location information by way of any suitable location-determination method while remaining consistent with an embodiment.

[0064] The processor 118 may further be coupled to other elements/peripherals 138, which may include one or more software and/or hardware modules/units that provide additional features, functionality and/or wired or wireless connectivity. For example, the elements/peripherals 138 may include an accelerometer, an e-compass, a satellite transceiver, a digital camera (e.g., for photographs and/or video), a universal serial bus (USB) port, a vibration device, a television transceiver, a hands free headset, a Bluetooth® module, a frequency modulated (FM) radio unit, a digital music player, a media player, a video game player module, an Internet browser, a virtual reality and/or augmented reality (VR/AR) device, an activity tracker, and the like. The elements/peripherals 138 may include one or more sensors, the sensors may be one or more of a gyroscope, an accelerometer, a hall effect sensor, a magnetometer, an orientation sensor, a proximity sensor, a temperature sensor, a time sensor; a geolocation sensor; an altimeter, a light sensor, a touch sensor, a magnetometer, a barometer, a gesture sensor, a biometric sensor, and/or a humidity sensor. [0065] The WTRU 102 may include a full duplex radio for which transmission and reception of some or all of the signals (e.g., associated with particular subframes for both the uplink (e.g., for transmission) and downlink (e.g., for reception) may be concurrent and/or simultaneous. The full duplex radio may include an interference management unit to reduce and or substantially eliminate self-interference via either hardware (e.g., a choke) or signal processing via a processor (e.g., a separate processor (not shown) or via processor 118). In an embodiment, the WTRU 102 may include a half-duplex radio for which transmission and reception of some or all of the signals (e.g., associated with particular subframes for either the uplink (e.g., for transmission) or the downlink (e.g., for reception)).

[0066] FIG. 1C is a system diagram illustrating the RAN 104 and the CN 106 according to an embodiment. As noted above, the RAN 104 may employ an E-UTRA radio technology to communicate with the WTRUs 102a, 102b, and 102c over the air interface 116. The RAN 104 may also be in communication with the CN 106.

[0067] The RAN 104 may include eNode-Bs 160a, 160b, 160c, though it will be appreciated that the RAN 104 may include any number of eNode-Bs while remaining consistent with an embodiment. The eNode-Bs 160a, 160b, 160c may each include one or more transceivers for communicating with the WTRUs 102a, 102b, 102c over the air interface 116. In an embodiment, the eNode-Bs 160a, 160b, 160c may implement MIMO technology. Thus, the eNode-B 160a, for example, may use multiple antennas to transmit wireless signals to, and receive wireless signals from, the WTRU 102a.

[0068] Each of the eNode-Bs 160a, 160b, and 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 uplink (UL) and/or downlink (DL), and the like. As shown in FIG. 1C, the eNode-Bs 160a, 160b, 160c may communicate with one another over an X2 interface. [0069] The CN 106 shown in FIG. 1C may include a mobility management entity (MME) 162, a serving gateway (SGW) 164, and a packet data network (PDN) gateway (PGW) 166. While each of the foregoing elements are depicted as part of the CN 106, it will be appreciated that any one of these elements may be owned and/or operated by an entity other than the CN operator.

[0070] The MME 162 may be connected to each of the eNode-Bs 160a, 160b, and 160c in the RAN 104 via an SI interface and may serve as a control node. For example, the MME 162 may be responsible for authenticating users of the WTRUs 102a, 102b, 102c, bearer activation/deactivation, selecting a particular serving gateway during an initial attach of the WTRUs 102a, 102b, 102c, and the like. The MME 162 may provide a control plane function for switching between the RAN 104 and other RANs (not shown) that employ other radio technologies, such as GSM and/or WCDMA. [0071] The SGW 164 may be connected to each of the eNode-Bs 160a, 160b, 160c in the RAN 104 via the SI interface. The SGW 164 may generally route and forward user data packets to/from the WTRUs 102a, 102b, 102c. The SGW 164 may perform other functions, such as anchoring user planes during inter-eNode-B handovers, triggering paging when DL data is available for the WTRUs 102a, 102b, 102c, managing and storing contexts of the WTRUs 102a, 102b, 102c, and the like.

[0072] The SGW 164 may be connected to the PGW 166, which may provide the WTRUs 102a, 102b, 102c with access to packet-switched networks, such as the Internet 110, to facilitate communications between the WTRUs 102a, 102b, 102c and IP-enabled devices.

[0073] The CN 106 may facilitate communications with other networks. For example, the CN 106 may provide the WTRUs 102a, 102b, 102c with access to circuit-switched networks, such as the PSTN 108, to facilitate communications between the WTRUs 102a, 102b, 102c and traditional land-line communications devices. For example, the CN 106 may include, or may communicate with, an IP gateway (e.g., an IP multimedia subsystem (IMS) server) that serves as an interface between the CN 106 and the PSTN 108. In addition, the CN 106 may provide the WTRUs 102a, 102b, 102c with access to the other networks 112, which may include other wired and/or wireless networks that are owned and/or operated by other service providers.

[0074] Although the WTRU is described in FIGs. 1A-1D as a wireless terminal, it is contemplated that in certain representative embodiments that such a terminal may use (e.g., temporarily or permanently) wired communication interfaces with the communication network. [0075] In representative embodiments, the other network 112 may be a WLAN.

[0076] A WLAN in infrastructure basic service set (BSS) mode may have an access point (AP) for the BSS and one or more stations (STAs) associated with the AP. The AP may have an access or an interface to a distribution system (DS) or another type of wired/wireless network that carries traffic into and/or out of the BSS. Traffic to STAs that originates from outside the BSS may arrive through the AP and may be delivered to the STAs. Traffic originating from STAs to destinations outside the BSS may be sent to the AP to be delivered to respective destinations. Traffic between STAs within the BSS may be sent through the AP, for example, where the source STA may send traffic to the AP and the AP may deliver the traffic to the destination STA. The traffic between STAs within a BSS may be considered and/or referred to as peer-to-peer traffic. The peer-to-peer traffic may be sent between (e.g., directly between) the source and destination STAs with a direct link setup (DLS). In certain representative embodiments, the DLS may use an 802. l ie DLS or an 802.1 Iz tunneled DLS (TDLS). A WLAN using an Independent BSS (IBSS) mode may not have an AP, and the STAs (e.g., all of the STAs) within or using the IBSS may communicate directly with each other. The IBSS mode of communication may sometimes be referred to herein as an "ad-hoc" mode of communication.

[0077] When using the 802.1 lac infrastructure mode of operation or a similar mode of operations, the AP may transmit a beacon on a fixed channel, such as a primary channel. The primary channel may be a fixed width (e.g., 20 MHz wide bandwidth) or a dynamically set width via signaling. The primary channel may be the operating channel of the BSS and may be used by the STAs to establish a connection with the AP. In certain representative embodiments, Carrier sense multiple access with collision avoidance (CSMA/CA) may be implemented, for example in in 802.11 systems. For CSMA/CA, the STAs (e.g., every STA), including the AP, may sense the primary channel. If the primary channel is sensed/detected and/or determined to be busy by a particular STA, the particular STA may back off. One STA (e.g., only one station) may transmit at any given time in a given BSS.

[0078] High throughput (HT) STAs may use a 40 MHz wide channel for communication, for example, via a combination of the primary 20 MHz channel with an adjacent or nonadj acent 20 MHz channel to form a 40 MHz wide channel.

[0079] Very high throughput (VHT) STAs may support 20 MHz, 40 MHz, 80 MHz, and/or 160 MHz wide channels. The 40 MHz, and/or 80 MHz, channels may be formed by combining contiguous 20 MHz channels. A 160 MHz channel may be formed by combining 8 contiguous 20 MHz channels, or by combining two non-contiguous 80 MHz channels, which may be referred to as an 80+80 configuration. For the 80+80 configuration, the data, after channel encoding, may be passed through a segment parser that may divide the data into two streams. Inverse fast fourier transform (IFFT) processing, and time domain processing, may be done on each stream separately. The streams may be mapped on to the two 80 MHz channels, and the data may be transmitted by a transmitting STA. At the receiver of the receiving STA, the above-described operation for the 80+80 configuration may be reversed, and the combined data may be sent to a medium access control (MAC) layer, entity, etc.

[0080] Sub 1 GHz modes of operation are supported by 802.1 laf and 802.11 ah. The channel operating bandwidths, and carriers, are reduced in 802.1 laf and 802.1 lah relative to those used in 802.1 In, and 802.1 lac. 802.1 laf supports 5 MHz, 10 MHz and 20 MHz bandwidths in the TV white space (TVWS) spectrum, and 802.1 lah supports 1 MHz, 2 MHz, 4 MHz, 8 MHz, and 16 MHz bandwidths using non-TVWS spectrum. According to a representative embodiment, 802.1 lah may support meter type control/machine-type communications (MTC), such as MTC devices in a macro coverage area. MTC devices may have certain capabilities, for example, limited capabilities including support for (e.g., only support for) certain and/or limited bandwidths. The MTC devices may include a battery with a battery life above a threshold (e.g., to maintain a very long battery life).

[0081] WLAN systems, which may support multiple channels, and channel bandwidths, such as 802.1 In, 802.1 lac, 802.11af, and 802.1 lah, include a channel which may be designated as the primary channel. The primary channel may have a bandwidth equal to the largest common operating bandwidth supported by all STAs in the BSS. The bandwidth of the primary channel may be set and/or limited by a STA, from among all STAs in operating in a BSS, which supports the smallest bandwidth operating mode. In the example of 802.1 lah, the primary channel may be 1 MHz wide for STAs (e.g., MTC type devices) that support (e.g., only support) a 1 MHz mode, even if the AP, and other STAs in the BSS support 2 MHz, 4 MHz, 8 MHz, 16 MHz, and/or other channel bandwidth operating modes. Carrier sensing and/or network allocation vector (NAV) settings may depend on the status of the primary channel. If the primary channel is busy, for example, due to a STA (which supports only a 1 MHz operating mode), transmitting to the AP, the entire available frequency bands may be considered busy even though a majority of the frequency bands remains idle and may be available.

[0082] In the United States, the available frequency bands, which may be used by 802.1 lah, are from 902 MHz to 928 MHz. In Korea, the available frequency bands are from 917.5 MHz to 923.5 MHz. In Japan, the available frequency bands are from 916.5 MHz to 927.5 MHz. The total bandwidth available for 802.1 lah is 6 MHz to 26 MHz depending on the country code.

[0083] FIG. ID is a system diagram illustrating the RAN 113 and the CN 115 according to an embodiment. As noted above, the RAN 113 may employ an NR radio technology to communicate with the WTRUs 102a, 102b, 102c over the air interface 116. The RAN 113 may also be in communication with the CN 115.

[0084] The RAN 113 may include gNBs 180a, 180b, 180c, though it will be appreciated that the RAN 113 may include any number of gNBs while remaining consistent with an embodiment. The gNBs 180a, 180b, 180c may each include one or more transceivers for communicating with the WTRUs 102a, 102b, 102c over the air interface 116. In an embodiment, the gNBs 180a, 180b, 180c may implement MIMO technology. For example, gNBs 180a, 180b may utilize beamforming to transmit signals to and/or receive signals from the WTRUs 102a, 102b, 102c. Thus, the gNB 180a, for example, may use multiple antennas to transmit wireless signals to, and/or receive wireless signals from, the WTRU 102a. In an embodiment, the gNBs 180a, 180b, 180c may implement carrier aggregation technology. For example, the gNB 180a may transmit multiple component carriers to the WTRU 102a (not shown). A subset of these component carriers may be on unlicensed spectrum while the remaining component carriers may be on licensed spectrum. In an embodiment, the gNBs 180a, 180b, 180c may implement Coordinated Multi-Point (CoMP) technology. For example, WTRU 102a may receive coordinated transmissions from gNB 180a and gNB 180b (and/or gNB 180c).

[0085] The WTRUs 102a, 102b, 102c may communicate with gNBs 180a, 180b, 180c using transmissions associated with a scalable numerology. For example, OFDM symbol spacing and/or OFDM subcarrier spacing may vary for different transmissions, different cells, and/or different portions of the wireless transmission spectrum. The WTRUs 102a, 102b, 102c may communicate with gNBs 180a, 180b, 180c using subframe or transmission time intervals (TTIs) of various or scalable lengths (e.g., including a varying number of OFDM symbols and/or lasting varying lengths of absolute time).

[0086] The gNBs 180a, 180b, 180c may be configured to communicate with the WTRUs 102a, 102b, 102c in a standalone configuration and/or a non- standalone configuration. In the standalone configuration, WTRUs 102a, 102b, 102c may communicate with gNBs 180a, 180b, 180c without also accessing other RANs (e.g., such as eNode-Bs 160a, 160b, 160c). In the standalone configuration, WTRUs 102a, 102b, 102c may utilize one or more of gNBs 180a, 180b, 180c as a mobility anchor point. In the standalone configuration, WTRUs 102a, 102b, 102c may communicate with gNBs 180a, 180b, 180c using signals in an unlicensed band. In a non- standalone configuration WTRUs 102a, 102b, 102c may communicate with/connect to gNBs 180a, 180b, 180c while also communicating with/connecting to another RAN such as eNode-Bs 160a, 160b, 160c. For example, WTRUs 102a, 102b, 102c may implement DC principles to communicate with one or more gNBs 180a, 180b, 180c and one or more eNode-Bs 160a, 160b, 160c substantially simultaneously. In the non- standalone configuration, eNode-Bs 160a, 160b, 160c may serve as a mobility anchor for WTRUs 102a, 102b, 102c and gNBs 180a, 180b, 180c may provide additional coverage and/or throughput for servicing WTRUs 102a, 102b, 102c.

[0087] Each of the gNBs 180a, 180b, 180c may be associated with a particular cell (not shown) and may be configured to handle radio resource management decisions, handover decisions, scheduling of users in the UL and/or DL, support of network slicing, dual connectivity, interworking between NR and E-UTRA, routing of user plane data towards user plane functions (UPFs) 184a, 184b, routing of control plane information towards access and mobility management functions (AMFs) 182a, 182b, and the like. As shown in FIG. ID, the gNBs 180a, 180b, 180c may communicate with one another over an Xn interface.

[0088] The CN 115 shown in FIG. ID may include at least one AMF 182a, 182b, at least one UPF 184a, 184b, at least one session management function (SMF) 183a, 183b, and at least one Data Network (DN) 185a, 185b. While each of the foregoing elements are depicted as part of the CN 115, it will be appreciated that any of these elements may be owned and/or operated by an entity other than the CN operator. [0089] The AMF 182a, 182b may be connected to one or more of the gNBs 180a, 180b, 180c in the RAN 113 via an N2 interface and may serve as a control node. For example, the AMF 182a, 182b may be responsible for authenticating users of the WTRUs 102a, 102b, 102c, support for network slicing (e.g., handling of different protocol data unit (PDU) sessions with different requirements), selecting a particular SMF 183a, 183b, management of the registration area, termination of non-access stratum (NAS) signaling, mobility management, and the like. Network slicing may be used by the AMF 182a, 182b, e.g., to customize CN support for WTRUs 102a, 102b, 102c based on the types of services being utilized by 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 MTC access, and/or the like. The AMF 182a, 182b may provide a control plane function for switching between the RAN 113 and other RANs (not shown) that employ other radio technologies, such as LTE, LTE-A, LTE-A Pro, and/or non-3GPP access technologies such as Wi-Fi.

[0090] The SMF 183a, 183b may be connected to an AMF 182a, 182b in the CN 115 via an N11 interface. The SMF 183a, 183b may also be connected to a UPF 184a, 184b in the CN 115 via an N4 interface. The SMF 183a, 183b may select and control the UPF 184a, 184b and configure the routing of traffic through the UPF 184a, 184b. The SMF 183a, 183b may perform other functions, such as managing and allocating UE IP address, managing PDU sessions, controlling policy enforcement and QoS, providing downlink data notifications, and the like. A PDU session type may be IP -based, non-IP based, Ethernet-based, and the like.

[0091] The UPF 184a, 184b may be connected to one or more of the gNBs 180a, 180b, 180c in the RAN 113 via an N3 interface, which may provide the WTRUs 102a, 102b, 102c with access to packet-switched networks, such as the Internet 110, e.g., to facilitate communications between the WTRUs 102a, 102b, 102c and IP-enabled devices. The UPF 184a, 184b may perform other functions, such as routing and forwarding packets, enforcing user plane policies, supporting multihomed PDU sessions, handling user plane QoS, buffering downlink packets, providing mobility anchoring, and the like.

[0092] The CN 115 may facilitate communications with other networks. For example, the CN 115 may include, or may communicate with, an IP gateway (e.g., an IP multimedia subsystem (IMS) server) that serves as an interface between the CN 115 and the PSTN 108. In addition, the CN 115 may provide the WTRUs 102a, 102b, 102c with access to the other networks 112, which may include other wired and/or wireless networks that are owned and/or operated by other service providers. In an embodiment, the WTRUs 102a, 102b, 102c may be connected to a local Data Network (DN) 185a, 185b through the UPF 184a, 184b via the N3 interface to the UPF 184a, 184b and an N6 interface between the UPF 184a, 184b and the DN 185a, 185b.

[0093] In view of FIGs. 1 A-1D, and the corresponding description of FIGs. 1 A-1D, one or more, or all, of the functions described herein with regard to any of WTRUs 102a-d, base stations 114a- b, eNode-Bs 160a-c, MME 162, SGW 164, PGW 166, gNBs 180a-c, AMFs 182a-b, UPFs 184a- b, SMFs 183a-b, DNs 185a-b, and/or any other element(s)/device(s) described herein, may be performed by one or more emulation elements/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.

[0094] The emulation devices may be designed to implement one or more tests of other devices in a lab environment and/or in an operator network environment. For example, the one or more emulation devices may perform the one or more, or all, functions while being fully or partially implemented and/or deployed as part of a wired and/or wireless communication network in order to test other devices within the communication network. The one or more emulation devices may perform the one or more, or all, functions while being temporarily implemented/deployed as part of a wired and/or wireless communication network. The emulation device may be directly coupled to another device for purposes of testing and/or may performing testing using over-the-air wireless communications.

[0095] The one or more emulation devices may perform the one or more, including all, functions while not being implemented/deployed as part of a wired and/or wireless communication network. For example, the emulation devices may be utilized in a testing scenario in a testing laboratory and/or a non-deployed (e.g., testing) wired and/or wireless communication network in order to implement testing of one or more components. The one or more emulation devices may be test equipment. Direct RF coupling and/or wireless communications via RF circuitry (e.g., which may include one or more antennas) may be used by the emulation devices to transmit and/or receive data.

[0096] Throughout embodiments described herein the terms "base station", "network", and "gNB", collectively "the network" may be used interchangeably to designate any network element such as e.g., a network element acting as a serving base station. Embodiments described herein are not limited to gNBs and are applicable to any other type of base stations.

[0097] For the sake of clarity, satisfying, failing to satisfy a condition, and configuring condition parameter(s) are described throughout embodiments described herein as relative to a threshold (e.g., greater, or lower than) a (e.g., threshold) value, configuring the (e.g., threshold) value, etc. For example, satisfying a condition may be described as being above a (e.g., threshold) value, and failing to satisfy a condition may be described as being below a (e.g., threshold) value. Embodiments described herein are not limited to threshold-based conditions. Any kind of other condition and param eter(s) (such as e.g., belonging or not belonging to a range of values) may be applicable to embodiments described herein.

[0098] Throughout embodiments described herein, (e.g., configuration) information may be described as received by a WTRU from the network, for example, through system information or via any kind of protocol message. Although not explicitly mentioned throughout embodiments described herein, the same (e.g., configuration) information may be pre-configured in the WTRU (e.g., via any kind of pre-configuration methods such as e.g., via factory settings), such that this (e.g., configuration) information may be used by the WTRU without being received from the network.

[0099] Throughout embodiments described herein, the expression "the WTRU may be configured with a set of parameters" is equivalent or may be used interchangeably with "the WTRU may receive configuration information (e.g., from another network element (e.g., gNB)) indicating a set of parameters". Throughout embodiments described herein, the expressions "the WTRU may report something", "the WTRU may be configured to report something", "the WTRU may send a report of (indicating) something" are equivalent or may be used interchangeably with "the WTRU may transmit (e.g., reporting) information indicating something".

[0100] Throughout embodiments described herein, the expressions "the WTRU may be signaled a parameter" and "the WTRU may be indicated with a parameter" are equivalent or may be used interchangeably with "the WTRU may receive information (e.g., from another network element (e.g., gNB)) indicating a parameter".

[0101] Throughout embodiments described herein, the expression "the WTRU may be indicated to perform an action" is equivalent or may be used interchangeably with "the WTRU may receive information (e.g., from another network element (e.g., gNB)) indicating to perform an action".

[0102] In embodiments described herein, "a" and "an" and similar phrases are to be interpreted as "one or more" and "at least one". Similarly, any term which ends with the suffix "(s)" is to be interpreted as "one or more" and "at least one". The term "may" is to be interpreted as "may, for example".

[0103] A symbol "/" (e.g., forward slash) may be used herein to represent "and/or", where for example, "A/B" may imply "A and/or B".

[0104] In embodiments described herein, "list of', "set of' and "one or more of' may be used interchangeably.

[0105] In embodiments described herein, "identity" and "identifier" may be used interchangeably to refer to how a network element (or a WTRU) may be identified. [0106] In embodiments described herein, a network element may refer to any kind of device including computing resources and networking capabilities, that may be connected to a network. The terms network element and node may be used interchangeably. A network element may be any kind of network infrastructure device and or a WTRU. The architecture depicted at FIG. IB for a WTRU 102 may be applicable more generally to any kind of network element.

[0107] Positioning Methods

[0108] In the third generation partnership project (3 GPP) Release 16, downlink, uplink and downlink and uplink positioning methods may be used.

[0109] In embodiments described herein, any of a DL positioning method, an UL positioning method and a DL & UL positioning method may be applicable.

[0110] A DL positioning method may refer to any positioning method that may use downlink reference signals such as e.g., positioning reference signals (PRS). The WTRU may receive multiple reference signals from transmission points (TP(s)) and may measure DL reference signal time difference (RSTD) and/or reference signal received power (RSRP). Examples of DL positioning methods may include any of downlink angle of departure (DL-AoD) and downlink time difference of arrival (DL-TDOA) positioning.

[OHl] A UL positioning method may refer to any positioning method that may use uplink reference signals such as e.g., sounding reference signals (SRS) for positioning. The WTRU may transmit SRS to multiple reception points (RPs) and the RPs may measure the UL relative time of arrival (RTOA) and/or RSRP. Examples of UL positioning methods may include any of UL- TDOA and uplink angle of arrival (UL-AoA) positioning.

[0112] A DL & UL positioning method may refer to any positioning method that may use uplink and downlink reference signals for positioning. In one example, a WTRU may transmit SRS to multiple TRPs and a gNB may measure Rx-Tx time difference which may be calculated based on the time of arrival of DL RS (e.g., PRS). The gNB may measure RSRP for the received SRS. The WTRU may measures Rx-Tx time difference for PRS transmitted from multiple TRPs. The WTRU may measure RSRP for the received PRS. The Rx-Tx difference and e.g., RSRP measured at WTRU and gNB may be used to compute round trip time. In embodiments described herein, a WTRU Rx - Tx time difference refers to the difference between arrival time of the reference signal transmitted by the TRP and transmission time of the reference signal transmitted from the WTRU. An example of DL & UL positioning method may be multi round trip time (RTT) positioning.

[0113] In 3GPP, WTRUs that may include ambient internet of things (loT) devices may transmit by backscattering (e.g., only). For RTT-based positioning, the WTRU (e.g., ambient loT device) may transmit a received DL RS (e.g., PRS). [0114] Collision of RSs transmitted by the WTRUs may occur e.g., at the gNB if a plurality of ambient loT devices deployed in the field attempt to reflect the received PRS at a same time (e.g., simultaneously). Embodiments described herein may allow to avoid the collision between backscattered signals from different WTRUs.

[0115] Overview of Time Domain Offset-based Signal Transmission

[0116] A WTRU may receive, from the network, configuration information indicating a timing offset at which the WTRU may be expected to backscatter. The WTRU may start a timer after (e.g., when) the WTRU may have determined that the WTRU may have received the reference DL-RS. After an amount of time corresponding to the (e.g., configured) timing offset may have elapsed (e.g., when the timer reaches the configured timing offset), the WTRU may transmit the received DL-RS which may be transmitted periodically. If the WTRU cannot transmit the received DL-RS at the configured timing offset, for example, based on insufficient (e.g., a lack of) harvested power, the WTRU may determine to attempt to transmit at the next transmission occasion, for example, based on the WTRU being able to harvest power satisfying a power condition (e.g., being above a preconfigured threshold).

[0117] In an example, the WTRU (e.g., ambient loT) may be configured by the network with any of a reference PRS sequence (e.g., pseudo noise (PN) sequence identifier (ID)), PRS periodicity (e.g., 2 milliseconds), a number of PRS occasions per cycle (e.g., four). In an example, the reference PRS may be transmitted (e.g., only) at reference timing.

[0118] In an example, the WTRU may receive a message (e.g., including information) indicating a timing offset with respect to the reference PRS Rx timing (e.g., a number T of occasion(s) after the reference PRS) from then network. The message may indicate when the WTRU may expect to receive the first PRS after the message (e.g., expected Tx).

[0119] In an example, the WTRU may receive the signal (e.g., if RSRP is above the threshold) and may determine whether the received signal is the reference PRS (e.g., sequence). If the received reference signal is not the reference PRS, the WTRU may continue searching (e.g., monitoring for a reference PRS) until the WTRU may find (e.g., receive) the reference PRS (e.g., sequence).

[0120] In an example, based on the reference PRS satisfying a power condition (e.g., RSRP above a threshold), the WTRU may transmit (e.g., backscatter) a received PRS (e.g., which may be different from the reference PRS) at indicated timing offset with respect to the reference PRS (e.g., the indicated number T of occasion(s) after the reference PRS). If the WTRU is not able to transmit at indicated timing offset (e.g., based on lack of (e.g., based on insufficient) Tx power), the WTRU may (e.g., determine to) transmit at next transmission occasion (e.g., the indicated number T of occasion(s) after the reference PRS). [0121] In an example, the WTRU may determine not to transmit after the WTRU may receive a termination message from the network (e.g., indicating a termination of the positioning method).

[0122] WTRU Behavior Overview

[0123] In an example, the WTRU may send a request to the network for configuration (e.g., any of PRS configurations, SRSp configurations) in any of the physical uplink shared channel (PUSCH), the physical uplink control channel (PUCCH), uplink control information (UCI), a MAC control element (MAC-CE), a radio resource control (RRC) message, an LTE positioning protocol (LPP) message. The request from the WTRU may include information indicating configuration(s) of any of a measurement gap, a PRS processing window, and a window for transmission of SRS for positioning (SRSp).

[0124] In an example, the WTRU may receive grant information from the network.

[0125] In an example, the WTRU may send an acknowledgement message in any of PUSCH and PUCCH for the grant information received from the network.

[0126] In an example, one or more conditions (e.g., criteria) may be used in a combination. The WTRU may be configured with one or more conditions and associated WTRU behavior. The WTRU may determine which behavior to use based on the applicable condition.

[0127] In an example, the WTRU may measure DL-PRS inside and/or outside of the active bandwidth part (BWP). The WTRU may transmit SRSp inside and/or outside of the active BWP.

[0128] In an example, the WTRU be preconfigured with parameters (e.g., any of one or more measurement gaps, one or more PRS processing windows, one or more PRS configurations, one or more SRSp configurations) via (e.g., based on receiving) a semi-static message (e.g., via any of LPP, RRC).

[0129] In an example, any actions that the WTRU may determine to take may be configured by the network. For example, the WTRU may be configured with a rule, associated with an action, and according to the rule, the WTRU may determine to take (e.g., perform) the associated action. [0130] In an example, in addition to the measurements performed on PRS, the WTRU may include (e.g., perform) one or more cell-related measurements, such as any of a synchronization signal block (SSB) RSRP from the serving cell with corresponding cell ID, a SSB RSRP from the neighboring cell(s) with corresponding cell ID(s), a RSRP of channel state information reference signal (CSI-RS) with CSI-RS resource ID, a RSRP of demodulation reference signal (DM-RS).

[0131] Terminology

[0132] In embodiments described herein, "Network" may include any of an AMF network element, a location management function (LMF) network element, a gNB and a new generation radio access network (NG-RAN) network element. [0133] In embodiments described herein, the terms "message" and "information" may be used interchangeably.

[0134] In embodiments described herein, the terms "pre-configuration" and "configuration" may be used interchangeably.

[0135] In embodiments described herein, the terms "non-serving gNB" and "neighboring gNB" may be used interchangeably.

[0136] In embodiments described herein, the terms "gNB" and "TRP" may be used interchangeably.

[0137] In embodiments described herein, the terms "PRS", "SRS", "SRS for positioning" and "SRS for positioning purpose" may be used interchangeably.

[0138] In embodiments described herein, the terms "PRS" and "PRS resource" may be used interchangeably.

[0139] In embodiments described herein, the terms "PRS(s)" and "PRS resource(s)" may be used interchangeably. The aforementioned "PRS(s)" or "PRS resource(s)" may belong to different PRS resource sets.

[0140] In embodiments described herein, the terms "PRS", "PRS transmission", "DL-PRS" and "DL PRS" may be used interchangeably.

[0141] In embodiments described herein, the terms "reference signal", and "reference signal transmission" may be used interchangeably.

[0142] In embodiments described herein, the terms "measurement gap" and "measurement gap pattern" may be used interchangeably. A measurement gap pattern may include (e.g., may be associated with) one or more parameters such as e.g., any of a measurement gap duration, measurement gap repetition period, and a measurement gap periodicity.

[0143] In embodiments described herein, a positioning reference unit (PRU) may be a WTRU or TRP whose location (e.g., any of altitude, latitude, geographic coordinate, or local coordinate) may be known by the network (e.g., any of gNB, LMF). Capabilities of a PRU may be same as a WTRU or a TRP, e.g., capable of any of receiving PRS, transmitting SRS (or SRS for positioning), reporting measurements, and transmitting a PRS. The WTRUs acting as PRUs may be used by the network for calibration purposes (e.g., any of correct unknown timing offset, correct unknown angle offset).

[0144] In embodiments described herein the terms "time offset with respect to an event" and "timing offset with respect to an event" may be used interchangeably and may be expressed in terms of a number T of occasion(s) after the event, where the occasion(s) represent a transmission opportunity, for example for transmitting a reflected (e.g., received) reference signal. [0145] An LMF network element may be non-limiting example of a network element that may be used for or to support positioning. Any other network element may be substituted for LMF and may be applicable to embodiments described herein.

[0146] In an example, the WTRU may receive configuration information indicating one or more preconfigured threshold(s) from the network (e.g., any of LMF, gNB) according to any embodiment described herein.

[0147] The line of sight (LOS) indicator may be any of a hard indicator (e.g., one or zero) or a soft indicator (e.g., any value between zero and one such as e.g., 0, 0.1, 0.2. ..,1). The LOS indicator may indicate a likelihood (e.g., probability) of the presence of an LOS path between a TRP and a WTRU or along PRS. The LOS indicator may be associated with any of a TRP and a PRS resource ID (e.g., index). In an example, the WTRU may receive information indicating the LOS indicator from the network per any of TRP and resource ID. In another example, the WTRU may determine the LOS indicator per any of TRP and resource ID based on measurements.

[0148] A WTRU location may be expressed in terms of any of altitude, latitude, geographic coordinate, and local coordinate, for example.

[0149] For the sake of clarity, embodiments are described herein with positioning reference signals (PRS). Any other types of reference signals are applicable to embodiments described herein.

[0150] Configurations for RS Positioning

[0151] Configurations for RS positioning are described herein.

[0152] Configurations for PRS

[0153] In one example, information indicating a PRS configuration may include (e.g., indicate) any of a number of symbols, a transmission power, a number of PRS resources included in a PRS resource set, a muting pattern for PRS (for example, the muting pattern may be expressed via a bitmap), a periodicity, a type of PRS (e.g., any of periodic, semi-persistent, aperiodic), a slot offset for periodic transmission for PRS, a vertical shift of PRS pattern in the frequency domain, a time gap during repetition, a repetition factor, a resource element (RE) offset, a comb pattern, a comb size, a spatial relation, a quasi co location (QCL) information (e.g., any of QCL target, QCL source) for PRS, a number of PRUs, a number of TRPs, an absolute radio-frequency channel number (ARFCN), a subcarrier spacing, an expected RSTD, an uncertainty in expected RSTD, a start physical resource block (PRB), a bandwidth, a BWP ID, a number of frequency layers, a start/end time for PRS transmission, an on/off indicator for PRS, a TRP ID, a PRS ID, a cell ID, a global cell ID, a PRU ID, and applicable time window. The WTRU may apply a PRS configuration under a condition that the (e.g., current) time may be within the applicable time window. The term "ID" may be used interchangeably with "index". The WTRU may receive beam width of a PRS or boresight direction (e.g., AoD) of PRS from the network. The configuration described herein is not limited to PRS. The configuration parameters described herein may be applicable to any (e.g., type of) DL RS.

[0154] Configurations for SRS for Positioning

[0155] In one example, information indicating a SRS (e.g., SRSp) configuration may include (e.g., indicate) any of (1) a resource ID, (2) comb offset values, (3) cyclic shift values, (4) a start position in the frequency domain, (5) a number of SRSp symbols, (6) a shift in the frequency domain for SRSp, (7) a frequency hopping pattern, (8) a type of SRSp (e.g., any of aperiodic, semi- persistent, periodic), (9) a sequence ID used to generate SRSp (or any other IDs used to generate SRSp sequence), (10) spatial relation information indicating which reference signal (e.g., any of DL RS, UL RS, CSLRS, SRS, DM-RS) or SSB (e.g, any of SSB ID, cell ID of the SSB) the SRSp may be related to spatially where the SRSp and DL RS may be aligned spatially, (11) QCL information (e.g., a QCL relationship between SRSp and other reference signals or SSB), (12) a QCL type (e.g, QCL type A, QCL type B, QCL type C, QCL type D), (13) a resource set ID, (14) a list of SRSp resources in the resource set, (15) a transmission power related information, (16) pathloss reference information which may include index for any of SSB, CSLRS, and PRS, (17) a periodicity of SRSp transmission; (18) and spatial information such as any of spatial direction information of SRSp transmission (e.g, beam information, angles of transmission), spatial direction information of DL RS reception (e.g, beam ID used to receive DL RS, angle of arrival). The term "ID" may be used interchangeably with "index".

[0156] Measurements

[0157] In one example, RSTD may be referred to as the difference in time of arrival between PRSs transmitted from a reference (e.g, first) TRP and target (e.g, second) TRP. The WTRU may be configured with the reference (e.g, first) TRP index and target (e.g, second) TRP index. The WTRU may be configured with the PRS resource indices to perform measurements. The WTRU may determine the time of arrival from TRP based on one or more PRS resources associated with the TRP. In another example, the RSTD may be referred to as the difference in time of arrival between the reference (e.g, first) PRS transmitted from a reference (e.g, first) TRP and the target (e.g, second) PRS transmitted from a target (e.g, second) TRP. In one example, the reference PRS and target PRS may be transmitted from the same TRP.

[0158] In one example, "WTRU Rx - Tx time difference" may refer to the difference between arrival time of the reference signal transmitted by the TRP and transmission time of the reference signal transmitted from the WTRU. The WTRU Rx-Tx time difference may be associated with PRS resource ID and/or SRSp resource ID. [0159] The WTRU may send (e.g., information indicating) one or more measurements in a report to the network (e.g., any of LMF, gNB) via any of a semi-static (e.g., any of LPP, RRC) and a dynamic message (e.g., any of UCI, UL MAC-CE).

[0160] Messages for Ambient loT Device

[0161] Messages (including any of configuration messages, control messages, and data messages) may be transmitted to the loT device, e.g., from any of a gNB and a WTRU. Messages may be transmitted by modulating encoded bits with a modulation scheme, such as e.g., ON/OFF keying, amplitude shift keying (ASK), frequency shift keying (FSK), etc. A carrier wave may be used to carry the modulation symbols, e.g., one or more characteristics of the carrier wave (e.g., any of amplitude, frequency, phase, etc.) may be changed to convey a modulation symbol. A carrier wave may be any of a signal of a single frequency and a signal containing multiple frequencies, such as e.g., a signal generated using an OFDM modulator.

[0162] Backscattering

[0163] In an example, a backscatter device may reflect an incoming RF signal and may not generate its own RF signal. In an example, the backscatter device may modulate an incoming RF signal Sin(t) to transmit its own data on the reflected signal. This may be achieved by using the impedance mismatch concept. An antenna impedance (which may be referred to as ZA) may be connected to a load impedance (which may be referred to as ZL) at the device. The reflection coefficient may be referred to as T = (ZL - ZA) / (ZL + ZA). The reflected signal may be referred to as Sout(t) = TxSin(t). By changing the reflection coefficient (e.g., by adjusting the load impedance) over time, any of the amplitude, frequency, etc. of the reflected signal may be changed (e.g., adjusted). For example, amplitude shift keying (ASK) modulation may be performed by using r=0 (non-reflecting state/OFF signal) or T = 1 (reflecting state/ON signal), as described, for example, by C. Xu et al. in "Practical Backscatter Communication Systems for Battery-Free Internet of Things: A Tutorial and Survey of Recent Research," published in IEEE Signal Processing Magazine, vol. 35, no. 5, pp. 16-27, Sept. 2018. The RFID standard is based on backscatter communications wherein RFID tags switch the reflection coefficient between two states based on the data being sent. ASK and PSK may be supported by the RFID tags.

[0164] Ambient loT Device Type

[0165] There may be different types of ambient loT devices. Three types (of ambient loT devices (device A, device B and device C) are described in 3GPP.

[0166] Ambient loT devices of device type A may not have energy storage and may not generate an RF signal. Device type A loT may backscatter an incoming signal. A device type A loT may have a capacitor to supply a small amount of power to run its circuitry. The capacitor may be filled using received RF power. [0167] Ambient loT devices of device type B may be similar to device type, with energy storage. The use of stored energy may include amplification for reflected signals.

[0168] Ambient loT devices of device type C may include energy storage, independent signal generation circuitry (e.g., active RF components for transmission). This type of device may be of lower complexity and power consumption than existing loT devices (e.g., narrowband (NB) loT devices).

[0169] loT devices of type A, B, and C may be able to demodulate any of control and data, etc. that may be received from the RAN according to connectivity topology.

[0170] Embodiments described herein may allow WTRUs to be located with improved accuracy based on its transmission of received PRS with reduced interference from other WTRUs.

[0171] Multiplexed Backscattering

[0172] Multiplexed backscattering is described herein.

[0173] In an example, the WTRU may be configured to transmit (e.g., backscatter) the received DL RS at the (e.g., configured) timing offset since the reception of the reference DL RS. The WTRU may determine the reception timing of the reference DL RS and may increment the counter after (e.g., when) the WTRU may receive DL RS which may be transmitted from the network. In a case where the counter reaches the (e.g., configured) timing offset, the WTRU may (e.g., determine to) perform backscattering, e.g., the WTRU may transmit the received DL-RS.

[0174] PRS Transmission Timeline

[0175] FIG. 2 is a diagram illustrating an example PRS transmission. WTRUs 21, 22 may receive PRS 23 or DL-RS (e.g., any of CSI-RS, SSB, demodulation reference signal (DMRS), phase tracking reference signal (PTRS)) from the network. Embodiments are described herein with the example of PRS as reference signals. Embodiments described herein may be applicable to any other type of reference signals.

[0176] FIG. 3 is a diagram illustrating an example transmission timeline of a TRP. An example of transmission of a message and PRS is shown in FIG. 3. In the example, the content of signal and/or reference signals transmitted from the network (e.g., any of LMF, gNB) are shown in FIG.

3. In the example, a message 30 (e.g., first information) may be sent to the WTRU from the network. The message 30 may be followed by a transmission of the reference PRS 31. For example, the WTRU may receive an indication (such as e.g., configuration information) from the network, indicating that the reference PRS 31, which may be referred to as first PRS, after the message may be received at least a second time offset 32 (e.g., T2) where the unit of second time offset 32 (e.g., T2) may be any of symbols, slots, frames, and seconds. After the transmission of the reference PRS 31, same or different PRS 33 may be transmitted from the network any of periodically, semi-persistently and a-periodically. [0177] In an example of periodic transmission of PRS, the WTRU may receive information indicating one or more configurations about the PRS transmission from the network, such as e.g., periodicity. The WTRU may determine that the periodic transmission may be terminated after the WTRU may have received an indication from the network indicating that the periodic transmission may be terminated.

[0178] In an example of semi-persistent PRS transmission, the WTRU may receive configuration information indicating, for example, a start time and an end time of the semi-persistent PRS transmission (e.g., a time period for performing reference signal transmissions). The start or end time may be indicated in terms of any of symbol, slot, frame number, system frame number (SFN) and absolute time. In another example, the WTRU may receive configuration information indicating a start time and a duration of semi-persistent transmission (e.g., a time period for performing reference signal transmissions). In another example, the WTRU may receive an activation message (e.g., via MAC-CE) from the network to indicate that the semi-persistent transmission may start in a number N of units (e.g., any of slots, frames, symbols). The WTRU may receive a deactivation message from the network, indicating that that the semi-persistent transmission may terminate in a number N of units (e.g., any of slots, frames, symbols).

[0179] In an example of aperiodic PRS transmission, the WTRU may receive a trigger message from the network (e.g., via downlink control information (DCI)) indicating that the NW may transmit PRS in a number N of units (e.g., any of slots, frames, symbols).

[0180] FIG. 4 is a diagram illustrating an example timeline for transmission of reference PRS and measurement PRS (mPRS) from the network. FIG. 4 illustrates the reference PRS and mPRS as two types of PRS. The message from the network may indicate one or more configurations for any type of PRS. In an example the reference PRS and a mPRS may be a same type of message. In the example, the reference PRS and mPRS may be transmitted at a first configured periodicity 41, which may be referred to as Pl.

[0181] In an example, a reference PRS may be transmitted from the network at a second configured periodicity 42, which may be referred to as P2 and which may be different from Pl. Periodicity of PRS or mPRS may be expressed (e.g., indicated) in terms of any of slots, symbols, frames, and absolute time (e.g., seconds). In an example, mPRSs may be transmitted for a (e.g., configured, indicated) number of repetitions (e.g., in a configured number of occasions) between transmission of reference PRSs. For example, in the example illustrated in FIG. 4, two occasions 43, 44 may be used by the network to transmit two mPRS between a first reference PRS and a second (e.g., subsequent) reference PRS.

[0182] FIG. 5 is a diagram illustrating another example timeline for transmission of a reference PRS and mPRS. In the example the first occasion of mPRS 51 may be transmitted after configured time offset 52 T1 from the end of the reference PRS 53. The time offset 52 T1 may be expressed (e.g., indicated) in terms of any of symbols, slots, frames and absolute time (e.g., seconds). The measurement PRSs may be transmitted at the (e.g., configured) periodicity 54.

[0183] In an example, the WTRU may be indicated to start backscattering, e.g., backscattering PRS, in a specific time. In one example, the WTRU may receive a message such as a configuration message and/or a control message. The message may include information indicating the timing of backscattering. For example, the timing information may be any of a value (e.g., T seconds, N slots, M frames, K symbols) and a pointer to a value. The WTRU may determine when to start backscattering based on the value. In one example, the WTRU may (e.g., be expected to) start backscattering T seconds after the end of the message.

[0184] In an example, the value may be determined by the WTRU implicitly. In an example, the value may be preconfigured. For example, a message of a (e.g., certain) type may be used to indicate transmission of PRS and the WTRU may determine that the WTRU may start backscattering T seconds after receiving this type of message. In another example, the message may contain a field to indicate start of PRS transmission.

[0185] In an example, the network element transmitting the PRS may start transmitting the PRS before the end of T seconds after the message transmission may end.

[0186] FIG. 6 is a diagram illustrating an example timeline. In this example, the gNB may start transmitting the PRS 61 (T + Td) seconds after transmission of the (e.g., configuration, control) message 62 may end. The WTRU may start backscattering (T + D) seconds after transmission of the message 62 where the time duration D may include the time for the propagation delay, receive processing such as demodulation, etc. By the time the gNB may start transmitting the PRS, the WTRU may have (e.g., already) started backscattering. For example, the time duration D may be any of configured and indicated by the network (e.g., any of gNB, LMF). In an example, the time duration may be indicated in the WTRU capability. In an example, the WTRU may be configured with a window by the network where the parameters of the window may include any of a start time (e.g., expressed in terms of any of an absolute time, an SFN, a slot or symbol number, a PRS transmission occasion number or ID), an end time and a duration (e.g., expressed in terms of any of the number of symbols, slots, frames) of the window. The start and/or stop time and/or the duration may be defined (e.g., indicated) with respect to an expected time of arrival of a DL reference signal. For example, the start time of the window may be defined (e.g., indicated as) XI seconds before the expected time of arrival of the DL PRS. For example, the end time of the window may be defined (e.g., indicated as) X2 seconds after the expected time of arrival of the DL PRS. In one example, the WTRU may determine to backscatter (e.g., transmit the received signal from the network) during or inside the configured window(s). The WTRU may determine to stop backscattering and/or may not backscatter outside of the configured window(s). In an example, if the WTRU receives a DL RS close to the end of the window, the WTRU may determine to backscatter the received signal until the end of the window (e.g., first N symbols of PRS). In an example, the WTRU may determine to backscatter partial DL RS (e.g., a subset of the received DL PRS) if the WTRU is not configured with a window of a size that may allow the WTRU to backscatter (e.g., all of) the received DL-RS. The WTRU may be configured with a periodicity of the window. The window may be aperiodic, e.g., the WTRU may have received an indication from the network indicating the timing at which the window may be activated. In another example, the window may be activated or deactivated by the network via e.g., a MAC-CE. In another example, the WTRU may determine to initiate backscatter during (e.g., based on) the window. The window may be used by the WTRU to determine when to perform backscattering. The WTRU may stop backscattering when (e.g., after) the WTRU may receive an indication from the network to stop backscattering.

[0187] Content of Messages from the Network

[0188] FIG. 7 is diagram illustrating an example signaling from the network (e.g., any of gNB, LMF). In the example, a first WTRU 71, which may be referred to as WTRU A and a second WTRU 72, which may be referred to as WTRU C, may be configured with a timing offset of respectively three occasions 73 and one occasion 74. The configured timing offset may be used by the WTRU to determine the transmission timing. The configuration may be included in a message received from the network (e.g., in any of physical downlink control channel (PDCCH), physical downlink shared channel (PDSCH), dedicated signal). The message may be included in any of DCI, a MAC-CE, a RRC message and a LPP message. The timing offset may be indicated in terms of any of symbols, slots, frames, SFNs, absolute time (e.g., seconds, minutes, hours) and occasion. [0189] The message may be a query including of bit field comprising one or more bits.

[0190] The message may include information related to PRS configurations indicating any of (1) a sequence ID, (2) one or more repetition factors, (3) information related PRS sequence, (4) a duration of PRS transmission, (5) a time offset of the reference PRS transmission with respect to the end of message, (6) a center frequency, and (7) one or more comb patterns.

[0191] A PRS may comprise (e.g., be associated with) a number N of complex values where N may be an integer. The complex values may correspond to values placed across any of N resource elements in the frequency domain and N samples in the time domain. Information related to reference PRS may comprise complex values of the reference PRS or information related to generation of the N complex values (such as e.g., indicating an initial seed for pseudo random number generator). [0192] In an example, the WTRU may determine the reference PRS based on the location of the reference PRS in the time domain and/or frequency domain. For example, the WTRU may receive information related to (e.g., indicating) an index (e.g., frame, slot, symbol, BWP, component carrier, carrier, starting or center frequency of the reference PRS) prior to receiving the reference PRS. Based on the indicated index, the WTRU may determine the sequence of the reference PRS. [0193] FIG. 8 is a diagram illustrating an example timeline for transmission of PRS from the network. The WTRU may receive information related to (e.g., indicating) an index 80 which may be related to any of the reference PRS 81 and mPRS 82. The WTRU may determine sequence of any of the reference PRS 81 and mPRS 82 based on any of the index 80 (e.g., slot index, frame index, symbol index, counter) information the WTRU may have received, and a seed for a pseudo random number generator.

[0194] In an example, the WTRU may determine the index information based on receiving a standalone message. The WTRU may determine the index information from the downlink channel (e.g., PDCCH, PDSCH) in the form of any of DCI, a MAC-CE, a RRC message and a LPP message.

[0195] Structure of a Message

[0196] In an example, the WTRU may receive more than one message from the network and the messages may include information related to (indicating) configuration. The WTRU may determine one or more configurations by decoding more than one message. The WTRU may receive a different subset of configuration in a different message. For example, the WTRU may receive information indicating an identifier for the WTRU (e.g., WTRU ID) in the first message indicating that the following messages (e.g., second, third messages) may be intended for the WTRU with the identifier indicated in the first message. In another example, the first message may include common configuration information (e.g., any of a center frequency for transmission of signal, a reference PRS sequence) and the second message may include information indicating a timing offset. In one example, the WTRU may determine to obtain the configuration in the second message based on the content of the first message. In another example, (e.g., all) information indicating a configuration may be included in a (e.g., single) message.

[0197] An example of identifier for WTRU may be any of a number, digits, etc. The identifier may comprise any of a seed and a complex number (e.g., comprising a real part and an imaginary part) based on which the WTRU may generate the WTRU specific signal or sequence for performing a backscattering or transmission operation. The WTRU identifier may comprise an ID or part of an ID stored at the WTRU (e.g., at the device memory). The WTRU ID may comprise an ID assigned by the gNB to the WTRU and/or (e.g., randomly) selected by the WTRU during a random-access procedure (e.g., radio network identifier (RNTI)). [0198] In an example, the WTRU may receive the messages (e.g., any of the first, second, third message) on one occasion (e.g., the same downlink channel may include all messages). The messages may be any of time division multiplexed (TDMed), frequency division multiplexed (FDMed) and encoded in the same message.

[0199] FIG. 9 is a diagram illustrating an example of more than one message arranged in a time division multiplex (TDM) manner. The WTRU may receive the first message 91 in symbol #2 through symbol #M and the second message 92 in symbol #K to symbol #N.

[0200] FIG. 10 is a diagram illustrating an example of more than one message arranged in a frequency division multiplex (FDM) manner. The WTRU may receive the first message 1010 in RE #M+1 to RE#N and the second message 1020 in RE#T to RE#K in the same or different symbols. In another example, the WTRU may receive sub-messages spread by spreading code across time and/or frequency.

[0201] Source of the Message

[0202] In an example, the WTRU may receive a message including details for one or more configurations from the network (e.g., any of LMF, gNB). In another example, the WTRU may receive the message from a network element managing configuration or resources such as a WTRU with server and/or LMF capability.

[0203] Relationship Between Reception Timing of the Message and Reception of the Reference PRS

[0204] The WTRU may be configured to expect reception or transmission of reference PRS after configured time (e.g., N slots) after reception or transmission of the message. An example is illustrated in FIG. 3 where the WTRU may be configured to receive the reference PRS 31 after a second time offset 32 (T2) where the unit of T2 may be any of slots, seconds, frames, symbols, etc. The WTRU may be any of configured and preconfigured with the second time offset 32. The WTRU may determine the second time offset 32 from the message 30 the WTRU may receive from the network. The WTRU may receive the message 30 by any of broadcast, groupcast and unicast.

[0205] Format of the Message

[0206] In an example, any messages the WTRU may receive from the network may be received as a standalone message or in the downlink channel (e.g., any of PDCCH, PDSCH). The message may be received in any of DCI, a MAC-CE, a RRC message and a LPP message. In another example, the message may be attached as the head or tail bits in the downlink channel. The message may be encoded by any of code division-based duplexing (CDM), time domain multiplexing (TDM) and frequency domain multiplexing (FDM) with the downlink channel. The message may be pigged backed in PDCCH and/or PDSCH. [0207] WTRU Behavior for Monitoring Message

[0208] In an example, the WTRU may be configured to monitor for a message. The WTRU may determine to search for the presence of the message at configured (e.g., or preconfigured) time and/or frequency resources. The WTRU may receive a message (e.g., via any of broadcast, groupcast and unicast) indicating time and/or frequency resources to monitor.

[0209] During random access, the WTRU may select a transmission resource (e.g., a time and/or frequency resource) to transmit an initial signal and/or a message to the gNB. The signal may comprise a preamble. The message may comprise a temporary WTRU ID which may be generated by the WTRU (e.g., randomly generated and/or generated from an ID stored at the device memory). In an example, the gNB may assign a WTRU ID to the WTRU. For example, the gNB may confirm the ID sent by the WTRU in the message. In another example, the gNB may send to the WTRU an ID. The WTRU ID agreed by the gNB and the WTRU may be used for subsequent communication (e.g., transmissions) between the gNB and the WTRU.

[0210] Request for Backscattering from the Network, WTRU Response

[0211] In an example, the WTRU may receive a request from the network (e.g., via any of RRC, LPP, MAC-CE, DCI) to perform backscattering or transmission procedure. In embodiments described herein, backscattering and transmission may be used interchangeably. The request may be contained (e.g., included, indicated) in the message described herein. The request may be expressed in a bit or sequence bits. For example, bit set to " 1 " may indicate to start backscattering, or bit set to "0" may indicate to transmit the preconfigured signal at indicated timing. In embodiment described herein, when described as an alternative to a backscattered transmission, transmitting a preconfigured signal refers to a non-backscattered transmission of a preconfigured signal.

[0212] In an example, the WTRU may receive DL RS which may indicate the request. In this case, the WTRU may be preconfigured with a RS indicating the request for backscattering. If the WTRU receives the RS from the network, the WTRU may determine to perform backscattering. The WTRU may be configured to monitor the RS at configured periodic occasions.

[0213] In an example, the WTRU may determine to transmit a response for the request. The WTRU may determine to transmit a configured (or preconfigured) sequence (or signal) to the network. The request from the network may include any of time offset information and frequency resource (e.g., center frequency) information at which the WTRU may transmit the signal as a reply. If the WTRU cannot perform backscattering at indicated time and/or frequency resources, the WTRU may be configured to transmit the (e.g., preconfigured) sequence. In another example, if the WTRU cannot perform backscattering at indicated time and/or frequency resources, the WTRU may be configured not to transmit the (e.g., preconfigured) sequence. [0214] FIG. 11 is a diagram illustrating an example protocol exchange between the WTRU and the network. The WTRU may receive a request 1110 from the network indicating to perform backscattering. The WTRU may send a response 1120 to the network indicating whether the WTRU is capable of performing backscattering (e.g., sufficient amount of power stored or harvested). The WTRU may receive information 1130 indicating one or more configurations for PRS from the network. The WTRU may receive PRS 1140. The WTRU may transmit a configured or preconfigured signal 1150 as backscatter.

[0215] Reporting from the WTRU

[0216] In an example, the WTRU may transmit a report (e.g., information) including any of the following information (e.g., measurement): (i) WTRU location information e.g., obtained from global navigation satellite system (GNSS), GPS, (ii) a timing advanced value, (iii) any of RSRP and reference signal received path power (RSRPP) of any of a DL RS and a signal, (iv) a RSTD between two DL RSs, (v) an AoA of DL RS, (vi) an estimated AoD of DL RS, (vii) a LOS status between TRP and WTRU, and (viii) a LOS status for DL RS. In an example, the presence of line of sight (LOS) or non-line of sight (NLOS) path may be indicated along AoD of PRS.

[0217] Any information (e.g., measurement) described hereabove may be associated with a timestamp (such as e.g., any of an absolute time, SFN, slot number, symbol number, frame number) indicating a time at which the information (e.g., measurement) may have been obtained or determined. The WTRU may send the report (e.g., information) based on the request from the network (e.g., any of gNB, LMF).

[0218] Timing Offset-based Backscattering

[0219] FIG. 12 is a diagram illustrating an example timeline where a first reference signal 1210 (e.g., the reference PRS) may be transmitted at periodicity of four occasions and a second reference signal 1220 (e.g., mPRS) may be transmitted (e.g., repeatedly) in between two reference PRSs 1210, 1250. In the example, the first 1210 and the second 1220 reference signals may be a same reference signal and may be transmitted at the same periodicity. In this example, the WTRU may not be configured with information related to the sequences of mPRS. The WTRU may be configured with information related to the sequence of the reference PRS (e.g., only).

[0220] Variations of What Signals the WTRU may Transmit During Backscattering Operation

[0221] In an example, the WTRU may receive information indicating a timing offset (e.g., such as number of repeated occasions after the reference PRS) in the message from the network, that the WTRU may wait before performing backscattering. In an example, the backscattering operation may comprise transmitting what the WTRU may receive. For example, as illustrated in FIG. 3, the WTRU may transmit the received PRS 34 (e.g., the WTRU may transmit (e.g., a reflected transmission of the second PRS 33 (referred as PRS#2) shown in FIG. 3).

[0222] In another example, the WTRU may transmit any of processed and modulated received PRS to the network. Examples of processing on received PRS may include adding any of phase shift and phase rotation to the received PRS. For example, the WTRU may modify (e.g., process) the received signal as as follows, w(t) = r(t)e^-7^ where r(t), w(t) and (p may represent received signal as a function of time t, transmitted signal and phase shift, respectively. In another example, the WTRU may modify (e.g., process) the received signal as follows, w(t) = r(t)e^_-^/^^>t or w(t) = r(t)e^_-^/^^,W where in the first equation, phase rotation may be added and in the second equation, phase rotation may be a function of time. The WTRU may receive configuration information related to (e.g., indicating) the amount of phase shift or rotation from the network.

[0223] In an example, the WTRU may determine to apply preconfigured code (e.g., any of spreading code, scrambling code) to the received signal and transmit the coded signal to the network. For example, the WTRU may determine to apply code division multiplexing (CDM) to the received signal. The WTRU may be configured with the code by the configuration message. The WTRU may be configured or preconfigured with more than one code and may receive a message from the network indicating which code to use among the more than one code.

[0224] In an example, the WTRU may be configured with a signal and/or sequence to transmit. The signal may be, for example, a reference signal. The WTRU may be configured with a number N of complex numbers and may use any of OFDM and DFT-s-OFDM to transmit the signal. The WTRU may transmit the signal when the WTRU may receive PRS at the (e.g., configured, indicated) timing offset with respect to the reference timing (e.g., timing at which the WTRU may receive the reference PRS). The sequence may comprise a sequence of complex numbers, which may be generated by a pseudo number generator with a configured (e.g., random) number seed. In another example, the WTRU may be any of preconfigured and hardcoded with a (e.g., specific) sequence or signal such that a (e.g., each) WTRU may be associated with a (e.g., unique) sequence or signal to assist the network to distinguish WTRUs based on received sequences or signals. Different WTRUs may be associated with different sequences or signals, to be differentiated by the network based on receiving different sequences or signals.

[0225] In an example, the WTRU may be configured with a sequence of bits (e.g., 1, -1) and the WTRU may use any of amplitude shift keying (ASK) and phase shift keying (PSK) to transmit the configured sequence.

[0226] In an example, based on the indication received from the network, the WTRU may determine to backscatter or transmit the preconfigured signal. For example, if the WTRU receives a line-of-sight (LOS) indicator (e.g., any of a hard indicator indicating 1 for LOS and 0 for non- LOS (NLOS), and a soft indicator with a (e.g., real) value between 0 and 1 indicating likelihood of the LOS). The WTRU may determine to backscatter or transmit the preconfigured signal if the LOS indicator satisfies a condition (e.g., is greater than a (e.g., configured) threshold (e.g., LOS indicator is greater than 0.5, LOS indicator is 1)). The LOS indicator may be associated with the PRS transmitted from the network, indicating the LOS status along the transmission direction of PRS. In an example, the LOS indicator may be associated with the TRP from which the PRS may be transmitted, indicating LOS status between the WTRU and the TRP.

[0227] In an example, the PRS configuration may implicitly identify a device. For example, the WTRU may be (pre)configured with a (e.g., specific) PRS sequence that may (e.g., uniquely) identify the device (e.g., WTRU). The (e.g., specific) PRS sequence may be associated with the WTRU. For example, the PRS sequence may comprise a set of time/frequency resources transmitted following a (e.g., common) signal (such as e.g., any of a backscattering signal and a (e.g., common) command signal). If the WTRU receives the PRS associated with it, the WTRU may transmit the received (e.g., modulated) PRS signal to the network. For example, the WTRU may identify its PRS signal (e.g., associated with the WTRU). The WTRU may initiate backscattering of any further PRS (or other signal) to the network, for example adding information according to embodiments described herein onto the backscattered signal.

[0228] In an example, the WTRU may receive a broadcast signal from the network. The WTRU may determine the timing offset corresponding to the WTRU.

[0229] In an example, a broadcast message may be decoded as described herein. The message may include a "message type" field (e.g., indication). If the message is a broadcast message, the field (e.g., indication) may be set to one of the broadcast messages. If the message type indicates unicast or groupcast, the WTRU may determine to decode the field (e.g., information) in the message which may include the ID for the WTRU or the group the WTRU may be associated with.

[0230] WTRU Behavior in Presence of Multipath Measurement

[0231] In one example, the WTRU may perform one or more measurements on the PRS and may determine the presence of multipath in the measurement. For example, the WTRU may detect the PRS and any of a replica and a phase rotated version of the PRS after a duration (e.g., of a number N of microseconds (e.g., after the PRS). An impulse response of a multipath channel may be referred to as h( here N, h_k(t) and T_k may be referred to as the number of multipaths, a time varying channel coefficient at the kth path and the time delay at the kth path, respectively. The WTRU may perform one or more measurements on the first path and delayed paths with respect to the first path. A (e.g., each) path may be associated with the relative delay with respect to the first path. A received power may be determined per path and a power difference between the first path and the kth path may be determined.

[0232] In an example, if the WTRU determines the presence of multipaths in the channel, the WTRU may determine to transmit the preconfigured signal (e.g., as a non-backscattered transmission of the preconfigured signal) to the network at configured timing offset (e.g., at the configured timing offset with respect to the reception timing of the reference PRS). If the WTRU does not detect the presence of multipaths (e.g., single path measurement), the WTRU may perform backscattering (e.g., the WTRU may transmit the received PRS). The WTRU may receive from the network (e.g., information indicating) a request to select (e.g., determine) between transmission of a preconfigured signal or backscattering based on the presence of the multipath in the measurement or not.

[0233] In an example, the WTRU may backscatter the received signal which may include one or more multipath components. The WTRU may receive from the network (e.g., information indicating) a request to backscatter the received signal independently (e.g., regardless) of the presence of the multipath measurement in the channel.

[0234] In one example, the WTRU may determine to start the timer based on reception timing of the signal in the first path.

[0235] Timing Offset, Timer and Reference Timing

[0236] Referring to FIG. 12, a first WTRU 1201 (which may be referred to as WTRU A) and a second WTRU 1202 (which may be referred to as WTRU C) may be configured with a timing offset of three occasions and one occasion, respectively. Configuring WTRUs with different timing offsets for backscattering may allow to reduce the likelihood of receiving colliding backscattered signals.

[0237] In an example, the WTRU may determine the timing offset from the message. In an example, the WTRU may be preconfigured with the timing offset (e.g., the WTRU may be hardcoded with the timing offset). In an example, the WTRU may report the timing offset value by (e.g., via) WTRU capability reporting, for example.

[0238] The timing offset may be defined with respect to a reference timing. An example of the reference timing may be when the WTRU may receive the reference PRS. For example, the WTRU may (e.g., also) be configured with the number of repetitions of PRS, which may be four repetitions, including the reference PRS, in the example shown at FIG. 12. The first WTRU 1201 may receive a first PRS 1210 (referred to as PRS #1) which may be the reference PRS. The first WTRU 1201 may determine that the received first PRS 1210 may be the reference PRS based on the sequence of PRS. According to the message, the first WTRU 1201 may determine to transmit the received signal 1240 (e.g., referred to as PRS#4 in the example) at three occasions from the reception of the reference PRS 1210. The WTRU may start a timer or counter to count the number of occasions based on a periodicity of PRS transmission. For example, if the periodicity between two repetitions is two milliseconds (ms), the WTRU may increment a counter at (e.g., every) two ms. When the WTRU's timer reaches the end of the repetition cycle (e.g., four in this example or eight ms), the WTRU may reset the timer. If the WTRU determines that the timing offset may be at three occasions from the reception of the reference PRS, e.g., six ms since the reception of the reference PRS if the configured periodicity between two consecutive PRSs is two ms, the first WTRU 1201 may transmit the received PRS 1240 (referred to as PRS#4 in FIG. 12). The first WTRU 1201 may transmit the received PRS in an occasion occurring an amount of time after the reception of the reference PRS 1210, the amount of time corresponding to a timing offset (e.g., a number of occasions) configured for the first WTRU 1201. In an example, a (e.g., each) occasion in a cycle may be associated with an occasion number in the cycle, and the timing offset may correspond to an occasion number in the cycle. An occasion number may be referred to herein as a reference signal occasion number.

[0239] In an example, the WTRU may reset the timer when the WTRU may receive the reference PRS or at the reference timing. The WTRU may reset and start the timer when the WTRU may receive the reference PRS or at the reference timing.

[0240] FIG. 13 is a diagram illustrating an example of timeline showing another example of timing offset. In the example, the WTRU 1301 may be configured with a timing offset 1305 of 5ms. The WTRU 1301 may start the timer when the WTRU 1301 may receive the reference PRS 1310. When the timer reaches the configured timing offset (e.g., 5ms), the WTRU may determine to transmit configured signal or (e.g., most) recently received signal 1311. In the illustrated example, the WTRU 1310 may determine to transmit the reference PRS for the timing offset of 5ms. In another example, the WTRU may be configured to transmit the next signal closest to the configured timing offset. For example, if the WTRU is configured with the timing offset of 5ms in the example shown at FIG. 13, the WTRU may determine to transmit PRS#2 and PRS#6. In another example, the WTRU may determine to transmit the signal that may be the closest to the configured timing offset (e.g., reference PRS#1 or PRS#2, whichever the signal whose reception timing may be closest to the configured timing of 5ms).

[0241] As described herein, the WTRU may determine to transmit the configured sequence or modulated signal to the network at the configured timing offset.

[0242] In another example, the reference timing may be a (e.g., specific) time. The WTRU may be configured with timing information (e.g., any of SFN, absolute time, such as 4 PM EST) at which the WTRU may be expected to start the timer.

[0243] In embodiments described herein, timer and counter may be used interchangeably. [0244] In another example, the WTRU may determine to increment the counter based on any of RSRP and RSRPP (RSRP per path) of the received PRS which may not be a reference PRS. The WTRU may increase the counter if RSRP of the received signal satisfies a condition (e.g., is above a (e.g., preconfigured) threshold).

[0245] Examples of WTRU Capability or Assistance Information of the WTRU

[0246] The WTRU may send its capability or assistance information to the network. Examples of capabilities include at least one of (1) a lower bound (e.g., minimum) or upper bound (e.g., maximum) timing offset for backscattering, (2), a (e.g., minimum) time (e.g., in any of seconds, symbols, slots or frames) for backscattering, (3) an amount of time it may take for the WTRU to harvest a (e.g., certain) level of power (e.g., N Watts), (4) a number of occasions the WTRU may backscatter a (e.g., certain) level of power (e.g., N Watts), (5) a type of DL signals or channels the WTRU may decode, (6) a WTRU ID, (7) a number of transmission and/or reception panels, dimension of the panel and number of elements in the panel, (8) a number or amount of signals the WTRU may be preconfigured or configured with, (9) one or more signals or spreading codes the WTRU may be hard coded, and (10) an upper bound (e.g., maximum) transmission power.

[0247] Transmission Power

[0248] In an example, the WTRU may not have enough power to transmit the received signal. In such a case, the WTRU may wait until the next occasion of the reference PRS to start the timer. In the example illustrated in FIG. 12, the second WTRU 1202 may be configured with the timing offset value of one occasion. In the example shown in FIG. 12, from the first occasion through the third occasion, the second WTRU 1202 may not be ready for transmission based on not having received enough power. The second WTRU 1202 may wait until the next reception of the reference PRS to start the timer. The WTRU may start a timer if at least one or combination of the following conditions is satisfied. The WTRU may start a timer if the power for transmission is above the (e.g., pre-) configured threshold and/or if the power for reception and/or decoding is above the (e.g., pre-) configured threshold.

[0249] The power mentioned hereabove may be power saved (e.g., retrieved) from energy harvesting.

[0250] The threshold may be configured by the network (e.g., by transmitting configuration information). The WTRU may be preconfigured or hard coded with a threshold for transmission power.

[0251] The WTRU may send a capability report to the network, indicating the time it may take for the WTRU to charge its battery via, for example, energy harvesting from a first percentage to a second percentage where the (first/second) percentage may indicate a WTRU battery charge level (such as e.g., how much charge the battery of the WTRU may have). [0252] Timer Stoppage Conditions

[0253] In an example, the WTRU may receive a PRS and if any of the RSRP and RSRPP of the received PRS is lower than the (e.g., configured) threshold, the WTRU may determine to stop the timer. The WTRU may stop the timer if RSRP of the received reference signal is below the (e.g., configured) threshold for more than a (e.g., configured) number of occasions (e.g., three occasions).

[0254] Transmission Behavior - Periodic/Semi-Persistent/Aperiodic

[0255] In an example, the WTRU may be configured to transmit any of periodically, semi- persistently and in an aperiodic manner. For example, the WTRU may receive a configuration message from the network indicating any of a (i) periodicity of transmission, (ii) a time window for periodic transmission, (iii) an activation (/deactivation) indication, and (iv) a number of transmissions.

[0256] In an example, the WTRU may be configured with a periodicity of transmission (e.g., any of one slot, the (e.g., every) occasion at the configured timing offset, 10 ms).

[0257] In an example, the WTRU may be configured with a time window for periodic transmission (e.g., transmit at (e.g., every) ten milliseconds for two seconds starting when the WTRU may receive the first reference PRS after the configuration message may be received, transmit at (e.g., every) ten milliseconds for two seconds starting when the WTRU may receive the configuration message).

[0258] In an example, the WTRU may receive an activation message from the network indicating to start the backscattering operation or transmission of the signal, and/or start the timer. The WTRU may receive a deactivation message from the network indicating to stop the backscattering operation or transmission of the signal and/or stop the timer. Any of the activation message and deactivation message may be in the form of a bit (e.g., " 1" for starting transmission, "0" for stopping transmission) and/or a message (e.g., a first message for starting transmission, a second message for stopping transmission).

[0259] In an example, the WTRU may be configured with the number of transmissions. For example, the WTRU may be configured to transmit the received PRS three times. The WTRU may transmit a received PRS at the configured time offset three times. The WTRU may receive a configuration message (e.g., indicating the number of (e.g., repeated) transmissions, e.g., the number of transmissions to be repeated).

[0260] Time limit for Backscattering

[0261] In an example, the WTRU may receive (e.g., information indicating) a request to backscatter within a number N of units (e.g., any of N seconds, N slots, N symbols). For example, the WTRU may receive an indication from the network, indicating that the WTRU may backscatter the received signal within N slots from the reception (e.g., of the indication). If the WTRU cannot transmit the received signal by the indicated time limit, the WTRU may determine to transmit a preconfigured signal. In another example, the WTRU may determine to transmit a message indicating that the WTRU cannot transmit any signal.

[0262] Frame Format / Slot Structure for the WTRU

[0263] In an example, the WTRU may receive configuration information indicating DL and/or UL timing.

[0264] FIG. 14 is a diagram illustrating an example of DL and UL format (e.g., slot structure) for the WTRU. In the example, the WTRU may receive a PRS during a first DL time interval 1410 (e.g., 14 OFDM symbols in the example). The WTRU may transmit the received signal during a first UL time interval 1420 (e.g., 14 OFDM symbols during the UL interval). The WTRU may use the configured frequency resources (e.g., bandwidth part, band) to transmit the signal. The duration of DL and/or UL interval may be any of preconfigured, configured, and hard coded by the network.

[0265] Muting for Backscattering

[0266] In an example, the WTRU may be configured with a muting pattern. The WTRU may receive a muting pattern (e.g., information) from the network indicating which occasion(s) the WTRU may skip backscattering and/or the WTRU may not expect to receive PRS based on PRS(s) being muted in the indicated occasions. Muting patterns may be configured by the network to reduce interference at the WTRU and/or gNB.

[0267] In an example, the muting pattern may be configured semi-statically, (e.g., any of activated, deactivated, and triggered). For example, the WTRU may receive information indicating the muting pattern in any of a RRC message and a LPP message. The WTRU may determine the muting pattern to be activated after the WTRU may have received the configuration message indicating the muting pattern, or at the indicated timing, e.g., N slots after the WTRU may have received the configuration message.

[0268] In an example, the WTRU may receive an activation message or deactivation message from the network, activating or deactivating a (e.g., configured) muting pattern. The WTRU may receive information indicating more than one muting patterns from the network where a (e.g., each) pattern may be associated with an index. The WTRU may receive, in activation or deactivation message, information indicating the index corresponding to one of the (e.g., configured) muting patterns.

[0269] In an example, the WTRU may receive a triggering message, triggering one of the (e.g., configured) muting patterns where the trigger message may indicate an index for one of the (e.g., configured) muting patterns. [0270] FIG. 15 is a diagram illustrating an example of WTRU Tx muting pattern. The WTRU 1501 may be configured with a muting pattern [1 1 0 1] where the WTRU may receive an indication from the network that a (e.g., each) bit of the muting pattern may correspond to a transmission occasion for the WTRU. For example, as shown at FIG. 15, the WTRU 1501 may be configured with the time offset of one occasion. The WTRU 1501 may transmit the received PRS 1502, 1505, 1511 one occasion after the reference PRS reception. According to the muting pattern, the WTRU may be expected to skip a (e.g., every) third transmission occasion 1508 out of four transmission occasions 1502, 1505, 1508, 1511. Thus, the WTRU may not transmit the received PRS 1508 (referred to as PRS#8) according to the configured muting pattern.

[0271] FIG. 16 is a diagram illustrating an example of WTRU Tx muting pattern with a granularity of repetitions. In the example, the WTRU 1601 may be configured with a muting pattern [1 1 0] where a (e.g., each) bit may correspond to a PRS transmission occasion. According to the configured muting pattern, the WTRU 1601 may determine that out of three PRS transmission occasions, the TRP may not transmit the third PRS. The WTRU 1601 may not expect to receive the third PRS 1603, the sixth PRS 1606, the ninth PRS 1609 and the twelfth PRS 1612 as shown in FIG. 16. The number of bits in the muting pattern may be determined based on the number of repetitions for PRS. For example, the WTRU 1601 may be configured with three repetitions in the example illustrated in FIG. 16.

[0272] FIG. 17 is a diagram illustrating an example of WTRU Tx muting pattern with a granularity of repetition group. In the example, the WTRU 1701 may configured with a muting pattern [1 0], The WTRU 1701 may receive an indication from the network indicating that a (e.g., each) bit may correspond to a group of repetitions. A group of repetitions may comprise a (e.g., configured) number of repetitions, e.g., three in the example. In the example, the WTRU 1701 may determine that the second group, out of two groups of repetitions may not be transmitted by the TRP. As illustrated in FIG. 17, the WTRU may not be expected to receive the fourth PRS 1704, the fifth PRS 1705, the sixth PRS 1706, the tenth PRS 1710, the eleventh PRS 1711 and the twelfth PRS 1712.

[0273] FIG. 18 is a diagram illustrating an example of WTRU Tx muting pattern with a granularity of repetition group and with a transmission of a reference PRS. The WTRU 1801 may receive an indication from the network indicating that a group of repetitions may be muted and that the reference PRS may be transmitted by the TRP. The WTRU 1801 may use the reference PRS to determine the timing for counting the number of occasions.

[0274] WTRU Behavior in Case of Lack of Transmission Power

[0275] In an example, a WTRU configured to perform backscattering may not be expected to decode the received signal (e.g., to be backscattered). The WTRU may decode (e.g., only) the reference PRS which may serve as the starting point for the WTRU to determine the timing at which the WTRU may transmit the received signal. Different WTRUs may be configured with different timing offsets such that the received signals from different WTRUs at the network may not collide.

[0276] The WTRU may be configured, by the network, to perform at least one of the following or combination of the following examples of transmission procedures.

[0277] In a first example of transmission procedure, if the power stored at the WTRU is below the (e.g., configured) threshold (e.g., the WTRU may not transmit signals due to lack of power), the WTRU may wait for the next occasion to receive the reference PRS for transmission.

[0278] In a second example of transmission procedure, if the power stored at the WTRU is below the (e.g., configured) threshold (e.g., the WTRU may not transmit signals due to lack of power), the WTRU may wait for the next occasion to receive the reference PRS for transmission. The WTRU may terminate transmission of received PRS if the WTRU may not accumulate enough transmission power within a (e.g., preconfigured) time limit (e.g., ten seconds since the WTRU may have received the message related to reference and/or measurement PRS).

[0279] In a third example of transmission procedure, if the power stored at the WTRU is below the (e.g., configured) threshold (e.g., the WTRU may not transmit signals due to lack of power), the WTRU may determine to terminate transmission of received PRS.

[0280] Termination Process

[0281] The WTRU may determine to terminate backscattering, or transmission operation based on receiving a termination message from the network via, for example, any of a RRC message, a LPP message, a MAC-CE and DCI, indicating to stop backscattering or transmission operation. In an example, the WTRU may be configured with the time limit and/or a duration to perform backscattering or transmission by the network. The WTRU may start the timer when the WTRU may receive the first reference PRS. The WTRU may stop (e.g., terminate) backscattering or transmission operation when the timer may expire or may reach the time limit. The WTRU may stop (e.g., terminate) backscattering or transmission operation after an amount of time (e.g., corresponding to the duration) may have elapsed since the reception of the first reference PRS.

[0282] In an example, the WTRU may determine to terminate backscattering or transmission operation if the WTRU determines that the WTRU may not be able to have enough power by the end of (e.g., an indicated time period for performing) PRS transmission, e.g., end of semi-persistent PRS duration, before aperiodic PRS reception.

[0283] The WTRU may determine to terminate backscattering or transmission operation if the WTRU determines that the WTRU may not have enough power to transmit the signal at a (e.g., preconfigured) time (e.g., within a time limit) before the end of (e.g., an indicated time period for performing semi-persistent) reference signal transmission. For example, the WTRU may determine that the WTRU may not be able to harvest enough power to transmit the received PRS at a number N of slots before the end of semi-persistent PRS transmission from the network.

[0284] Acknowledgment Transmission

[0285] In an example, the WTRU may transmit the received reference PRS to indicate acknowledgement reception of the reference PRS. In another example, the WTRU may transmit the configured signal to indicate acknowledgement reception of the reference PRS.

[0286] Example of Time Domain Offset-based Signal Transmission

[0287] In an example, the WTRU (e.g., ambient loT) may be configured by the network with any of a reference PRS sequence (e.g., pseudo noise (PN) sequence identifier (ID)), PRS periodicity (e.g., 2 milliseconds), a number of PRS occasions per cycle (e.g., four). In an example, the reference PRS may be transmitted (e.g., only) at reference timing.

[0288] In an example, the WTRU may receive a message (e.g., including information) indicating a timing offset with respect to the reference PRS Rx timing (e.g., a number T of occasion(s) after the reference PRS) from then network. The message may indicate when the WTRU may expect to receive the first PRS after the message (e.g., expected Tx).

[0289] In an example, the WTRU may receive the signal (e.g., if RSRP is above the threshold) and may determine whether the received signal is the reference PRS (e.g., sequence). If the received reference signal is not the reference PRS, the WTRU may continue searching (e.g., monitoring for a reference PRS) until the WTRU may find (e.g., receive) the reference PRS (e.g., sequence).

[0290] In an example, based on the reference PRS satisfying a power condition (e.g., RSRP above a threshold), the WTRU may transmit (e.g., backscatter) a received PRS (e.g., which may be different from the reference PRS) at indicated timing offset with respect to the reference PRS (e.g., the indicated number T of occasion(s) after the reference PRS). If the WTRU is not able to transmit at indicated timing offset (e.g., based on lack of (e.g., based on insufficient) Tx power), the WTRU may (e.g., determine to) transmit at next transmission occasion (e.g., the indicated number T of occasion(s) after the reference PRS).

[0291] In an example, the WTRU may determine not to transmit after the WTRU may receive a termination message from the network (e.g., indicating a termination of the positioning method).

[0292] Timing Offset and FDM-based Backscattering

[0293] FDM-based backscattering is described herein.

[0294] Message Content

[0295] In an example, the WTRU may receive configuration information indicating any of one or more timing and frequency characteristics. Examples of frequency characteristics may include any of (i) a center frequency, (ii) a bandwidth (e.g., expressed in terms of any of MHz, number of resource blocks or resource elements), (iii) a comb pattern, (iv) an ID for transmission filter if the WTRU is configured or preconfigured with more than one transmission filters. The WTRU may determine to transmit the signal based on the configured (e.g., indicated) one or more frequency characteristics.

[0296] In an example, the configuration and/or control message may indicate which sub-band to use. In one method, the WTRU may modulate the backscattered signal to the indicated sub-band (e.g., center frequency of the sub -band).

[0297] Backscattering with Configured Frequency Characteristics

[0298] In an example, the WTRU may receive information indicating to transmit the received signal at a (e.g., configured) timing offset. In addition, the WTRU may receive (e.g., in any of the same information or different information) an indication to transmit the received signal at the (e.g., configured) frequency characteristics, e.g., at the configured center frequency and indicated transmission filter or bandwidth.

[0299] FIG. 19 is a diagram illustrating an example of configured transmission filters for a WTRU. The WTRU may be any of configured, preconfigured, and hard coded with two filters 1910 1920, as illustrated in FIG. 19, with the same bandwidth (BW). The filters 1910 1920 may have different center frequencies as shown in FIG. 19. The WTRU may receive an indication or configuration from the network indicating which filter to use. When the WTRU may transmit the received DL reference signal, the WTRU may use the indicated filter, to transmit part of the received DL reference signal.

[0300] In an example, the WTRU may modulate the backscattered signal (e.g., with a corresponding wave such as a sinusoidal wave or a square wave) and may shift the backscattered signal to a (e.g., certain) frequency. For example, the WTRU may modulate the backscattered PRS to shift the signal to a first center frequency 1911 (fl) associated with the first filter 1910 or a second center frequency 1922 (f2) associated with the second filter 1920.

[0301] In an example, the WTRU may be configured with more than one frequency range. The configured frequency ranges may overlap in the frequency domain. A (e.g., each) range may be expressed in terms of a number of any of resource elements (Res), resource blocks (RBs), and frequency (Hz). A (e.g., each) range may be associated with different center frequencies or start and/or end point in the frequency (e.g., expressed in terms of any of RB index, RE index, frequency). A (e.g., each) range may be associated with a (e.g., unique) index.

[0302] FIG. 20 is a diagram illustrating an example of FDM-based backscattering. In the example, WTRUs may be preconfigured with two filters shown in FIG. 19 where the first frequency may be lower than the second frequency and bandwidth of the first and second filters may be the same. As an example, the filter with the center frequency at fl and f2 may be referred with filter index 1 filter index 2, respectively. In the example, the transmitted PRS may span bandwidth between a starting frequency referred to as fs and an ending frequency referred to as fe where the starting frequency may be lower than the ending frequency (fs<fe). In the example, a first WTRU 2001, a second WTRU 2002, a third WTRU 2003 and a fourth WTRU 2004 may be configured with the timing offsets of three occasions, three occasions, one occasion and one occasion, respectively. The first WTRU 2001, the second WTRU 2002, the third WTRU 2003 and the fourth WTRU 2004 may be configured with the filter index, 1, 2, 1 and 2, respectively.

[0303] As shown in FIG. 20, the first WTRU 2001 may transmit the fourth received PRS 2040 (referred to as PRS#4) and a first eighth received PRS 2081 (referred to as PRS #8) after three occasions from the reception of the reference PRS 2010, 2050 using the filter with the first index (referred to as index 1). The second WTRU 2002 may transmit a second eighth received PRS 2082 (referred to as PRS#8) after three occasions from the reception of the reference PRS 2050 using the filter with the second index (referred to as index 2). The third WTRU 2003 may transmit a first sixth received PRS 2061 (referred to as PRS#6) after one occasion from the reception of the reference PRS 2050 using the filter with the first index. The fourth WTRU 2004 may transmit the second received PRS 2020 (referred to as PRS#2) and the second sixth received PRS 2062 (referred to as PRS #6) after one occasion from the reception of the reference PRS 2010, 2050 using the filter with the second index. As shown in the example, the collision between backscattering WTRUs may be avoided.

[0304] Example of Time Offset-based and EDM- based Signal Transmission

[0305] In an example, the WTRU (e.g., ambient loT) may be configured by the network with any of a reference PRS sequence (e.g., pseudo noise (PN) sequence identifier (ID)), PRS periodicity (e.g., 2 milliseconds), a number of PRS occasions per cycle (e.g., four). In an example, the reference PRS may be transmitted (e.g., only) at reference timing.

[0306] In an example, the WTRU may receive a message (e.g., including information) indicating a timing offset with respect to the reference PRS Rx timing (e.g., a number T of occasion(s) after the reference PRS) from then network. The message may indicate when the WTRU may expect to receive the first PRS after the message (e.g., expected Tx).

[0307] In an example, the WTRU may receive the second message indicating hopping pattern indication (such a e.g., a WTRU specific offset). An example of hopping pattern may include [1 0] where "1" may correspond to the upper sub-band, "0" may correspond to the lower sub-band. The index (1 or 0) may be determined based on reference occasion index (e.g., mod (ref hop index, number of PRS occasions per cycle) + WTRU specific offset). [0308] In an example, the WTRU may receive the signal (e.g., if RSRP is above the threshold) and may determine whether the received signal is the reference PRS. If the received signal is not the reference PRS, the WTRU may continue the search (e.g., may monitor for a reference PRS) until the WTRU may receive the reference PRS. If the WTRU cannot transmit at the indicated timing offset (e.g., based on a lack of Tx power), the WTRU may determine to transmit at next transmission occasion (e.g., T occasion(s) after the reference PRS).

[0309] The WTRU may transmit the indicated sub-band of received PRS at indicated timing offset with respect to the reference PRS (e.g., T occasion(s) of the reference PRS).

[0310] Other Example of Time Offset-based and EDM- based Signal Transmission

[0311] In an example, the WTRU may receive a first message indicating a timing offset (e.g., T ms).

[0312] In an example, the WTRU may receive a second message indicating hopping pattern indication (e.g., a starting sub-band, whether to alternate or repeat, if repeat number of repetitions). An example of hopping pattern may include [1 0], where "1" may correspond to an upper subband, and "0" may correspond to a lower sub-band.

[0313] In an example, the WTRU may receive the reference PRS (if the method is repetition occasion based).

[0314] In an example, the WTRU may receive the target PRS.

[0315] In an example, the WTRU may transmit in the sub-band of PRS indicated in the pattern at indicated timing offset (e.g., T milliseconds after reception of the reference PRS) with respect to the reference PRS.

[0316] In an example, the WTRU may stop transmission after transmitting PRS for the indicated number of repetitions.

[0317] Backscattering with Configured Frequency Hopping

[0318] FIG. 21 is a diagram illustrating an example configuration of timing offset and hopping pattern. In the example, the WTRUs may be configured with one or more timing offsets and one or more hopping patterns.

[0319] As shown in FIG. 21, a first WTRU 2101, a second WTRU 2102, a third WTRU 2103 and a fourth WTRU 2104 may be configured with the timing offsets of three occasions 2130, three occasions 2130, one occasion 2110 and one occasion 2110, respectively. In an example, the first WTRU 2101 and the second WTRU 2102 may configured with a first frequency hopping pattern 2111. The third WTRU 2103 and the fourth WTRU 2104 may be configured with a second frequency hopping pattern 2112.

[0320] The first frequency hopping pattern 2111 may be represented by [1 2] and the second frequency hopping pattern 2112 may be represented by [2 1], The element in the vector [1 2] may indicate the filter index as illustrated in FIG. 19. Using hopping in the frequency domain (e.g., using different Tx filters at different occasions) may allow to improve bandwidth coverage and to improve the quality of timing, power, phase and/or angle measurements.

[0321] In an example, the WTRU may receive information indicating frequency hopping pattern and time offset values in a same message or different (e.g., separate) configuration messages.

[0322] In an example, the WTRU may determine to use the filter index sequentially according to the configured hopping pattern. For example, the WTRU may determine to use the filter associated with the first index in the pattern when the WTRU may transmit or backscatter for a first time after receiving the configuration message. After using the filter associated with the first index, the WTRU may determine to use the filter associated with the second index for the subsequent transmission or backscattering.

[0323] FIG. 22 is a diagram illustrating an example of backscattering with frequency hopping and time shift. A first WTRU 2201 may transmit a fourth received PRS 2240 (referred to as PRS#4) and a first eighth received PRS 2281 (referred to as PRS #8) after three occasions from the reception of the reference PRS 2210, 2250 using the filter with a first index 2211 and a second index 2212 respectively. A second WTRU 2202 may transmit a second eighth received PRS 2282 (referred to as PRS#8) after three occasions from the reception of the reference PRS 2250 using the filter with the first index 2211. A third WTRU 2203 may transmit a first sixth received PRS 2261 (referred to as PRS#6) after one occasion from the reception of the reference PRS 2250 using the filter with the second index 2212. A fourth WTRU 2204 may transmit a second received PRS 2220 (referred to as PRS#2) and a second sixth received PRS 2262 (referred to as PRS #6) after one occasion from the reception of the reference PRS 2210, 2250 using the filter with the second index 2212 and the first index 2211, respectively. As shown in the example, the collision between backscattering WTRUs can be avoided.

[0324] FIG. 23 is a diagram illustrating an example method 2300 for multiplexed backscattering. The method 2300 may be implemented in a WTRU. As shown at 2310, the WTRU may receive first information indicating a first time offset with respect to a first reference signal transmission. As shown at 2320, the WTRU may receive the first reference signal transmission. As shown at 2330, the WTRU may determine whether the received first reference signal transmission satisfies a power condition. As shown at 2340, the WTRU may receive a second reference signal transmission. As shown at 2350, the WTRU may transmit a third reference signal transmission based on (1) the received second reference signal transmission, (2) the indicated first time offset, and (3) whether the received first reference signal transmission satisfies the power condition. For example, the third reference signal transmission may be transmitted based on the received second reference signal transmission at the indicated time offset with respect to the first reference signal transmission and responsive to the power condition being satisfied (e.g., for any of the received first reference signal transmission and the received second reference signal transmission).

[0325] In various embodiments, the third reference signal transmission may be transmitted by backscattering the second reference signal transmission.

[0326] In various embodiments, the third reference signal transmission may be transmitted by reflecting an energy received from the second reference signal transmission.

[0327] In various embodiments, the WTRU may receive (e.g., first) configuration information indicating any of a reference signal sequence, a reference signal periodicity, and a number of reference signal occasions per cycle.

[0328] In various embodiments, the first information may indicate a second time offset between a first information transmission and the first reference signal transmission.

[0329] In various embodiments, the received first reference signal transmission may satisfy the power condition (e.g., the power condition may be satisfied for the received first reference signal transmission) in a case where a (e.g., first) reference signal received power is above a (e.g., first) threshold.

[0330] In various embodiments, the WTRU may transmit the third reference signal transmission in a case where the received first reference signal transmission satisfies the power condition.

[0331] In various embodiments, the WTRU may determine that the received first reference signal transmission satisfies the power condition, and the WTRU may transmit the third reference signal transmission at the indicated first time offset with respect to the first reference signal transmission. [0332] In various embodiments, the WTRU may (e.g., be operable to) monitor for a subsequent first reference signal transmission in a case where the received first reference signal transmission fails to satisfy the power condition.

[0333] In various embodiments, the WTRU may transmit the third reference signal transmission in a case where (e.g., responsive to) the received second reference signal transmission satisfies the power condition (e.g., in a case where a (e.g., second) reference signal received power is above a (e.g., second) threshold).

[0334] In various embodiments, in a case where the received second reference signal transmission fails to satisfy the power condition, the WTRU may receive a fourth reference signal transmission and may transmit the third reference signal transmission based on the received fourth reference signal transmission at a third time offset with respect to the first reference signal transmission, wherein the third time offset may be an integer number of the first time offset.

[0335] In various embodiments, the first information may indicate a frequency hopping pattern. [0336] In various embodiments, the frequency hopping pattern may comprise a pattern of a plurality of sub-band indexes. In various embodiments, the first time offset may be associated with an index, and the WTRU may determine a sub-band index from the plurality of sub-band indexes based on the index of the first time offset.

[0337] In various embodiments, the WTRU may transmit the third reference signal transmission in a sub-band associated with the sub-band index.

[0338] FIG. 24 is a diagram illustrating another example method 2400 for multiplexed backscattering. The method 2400 may be implemented in a WTRU. As shown at 2410, the WTRU may receive (e.g., from a network) first information indicating a first time offset with respect to a first reference signal transmission. As shown at 2420, the WTRU may receive (e.g., from the network) the first reference signal transmission. As shown at 2440, the WTRU may receive a second reference signal transmission. As shown at 2450, the WTRU may transmit (e.g., to the network) a third reference signal transmission based on the received second reference signal transmission at the indicated first time offset. In various embodiments, the third reference signal transmission may be transmitted responsive to a power condition being satisfied.

[0339] In various embodiments, transmitting the third reference signal transmission may comprise backscattering the second reference signal transmission.

[0340] In various embodiments, transmitting the third reference signal transmission may comprise reflecting an energy received from the second reference signal transmission.

[0341] In various embodiments, the WTRU may receive first configuration information indicating any of a reference signal sequence, a reference signal periodicity, and a number of reference signal occasions per cycle.

[0342] In various embodiments, the first time offset may correspond to a reference signal occasion number in the cycle.

[0343] In various embodiments, the first information may indicate a second time offset between a first information transmission and the first reference signal transmission.

[0344] In various embodiments, the third reference signal transmission may be transmitted responsive to the power condition being satisfied for the received first reference signal transmission.

[0345] In various embodiments, the power condition may be satisfied for the received first reference signal in a case where a first reference signal received power is above a first threshold.

[0346] In various embodiments, the third reference signal transmission may be transmitted responsive to the power condition being satisfied for the received second reference signal transmission.

[0347] In various embodiments, the power condition may be satisfied for the received second reference signal transmission in a case where a second reference signal received power of the received second reference signal transmission is above a second threshold. [0348] In various embodiments, the first information may indicate a frequency hopping pattern. [0349] In various embodiments, the frequency hopping pattern may comprise a pattern of a plurality of sub-band indexes. In various embodiments, the first time offset may be associated with an index, and the WTRU may determine a sub-band index from the plurality of sub-band indexes based on the index of the first time offset.

[0350] In various embodiments, transmitting the third reference signal transmission may comprise transmitting the third reference signal transmission in a sub-band associated with the sub-band index.

[0351] In various embodiments, the WTRU may receive second configuration information indicating a time period for performing reference signal transmissions.

[0352] In various embodiments, the WTRU may determine that the WTRU may not have enough power to perform the reference signal transmissions by an end of the time period.

[0353] In various embodiments, the WTRU may terminate performing the reference signal transmissions based on the WTRU not having enough power to perform the reference signal transmissions by an end of the time period.

[0354] In various embodiments, the WTRU may determine that the WTRU may not have enough power to perform the reference signal transmissions within a time limit before an end of the time period.

[0355] In various embodiments, the WTRU may terminate performing the reference signal transmissions based on the WTRU not having enough power to perform the reference signal transmissions within a time limit before an end of the time period.

[0356] FIG. 25 is a diagram illustrating an example method 2500 for multiplexed backscattering. The method 2500 may be implemented in a network element. As shown at 2510, the network element may transmit first information to a first WTRU. In various embodiments, the first information may indicate a first time offset with respect to a first reference signal transmission of a plurality of reference signal transmissions. As shown at 2520, the network element may transmit second information to a second WTRU. In various embodiments, the second information may indicate a second time offset with respect to the first reference signal transmission. In various embodiments, the first time offset may be different from the second time offset. As shown at 2530, the network element may transmit the plurality of reference signal transmissions. As shown at 2540, the network element may receive from the first WTRU, a second reference signal transmission at the first time offset with respect to the first reference signal transmission. As shown at 2550, the network element may receive from the second WTRU, a third reference signal transmission at the first time offset with respect to the first reference signal transmission. [0357] FIG. 26 is a diagram illustrating an example method 2600 for backscattering in presence of multipath. The method 2600 may be implemented in a WTRU. As shown at 2610, the WTRU may receive information indicating a time offset with respect to a reference signal transmission. As shown at 2620, the WTRU may receive the reference signal transmission. As shown at 2630, the WTRU may perform measurement on the reference signal transmission to detect a presence of multipath. As shown at 2640, the WTRU may transmit a preconfigured signal at the indicated time offset with respect to the reference signal transmission. In various embodiments, the preconfigured signal may be transmitted responsive to the presence of multipath being detected.

[0358] FIG. 27 is a diagram illustrating an example method 2700 for backscattering in presence of multipath. The method 2700 may be implemented in a network element. As shown at 2710, the network element may transmit information indicating a time offset with respect to a reference signal transmission. As shown at 2720, the network element may transmit the reference signal transmission. As shown at 2730, the network element may receive a preconfigured signal at the indicated time offset with respect to the reference signal transmission. In various embodiments, the preconfigured signal may indicate a presence of multipath being detected at the WTRU.

[0359] While not explicitly described, embodiments described herein may be employed in any combination or sub-combination. For example, the present principles are not limited to the described variants, and any arrangement of variants and embodiments can be used.

[0360] Besides, any characteristic, variant or embodiment described for a method is compatible with an apparatus device comprising means for processing the disclosed method, with a device comprising circuitry, including any of a transmitter, a receiver, a processor and a memory, the circuitry being configured to process the disclosed method, with a computer program product comprising program code instructions and with a non-transitory computer-readable storage medium storing program instructions. Besides, any characteristic, variant or embodiment described for a WTRU is compatible with an (e.g., infrastructure) network element of the cellular network.

[0361] Although features and elements are provided above in particular combinations, one of ordinary skill in the art will appreciate that each feature or element can be used alone or in any combination with the other features and elements. The present disclosure is not to be limited in terms of the particular embodiments described in this application, which are intended as illustrations of various aspects. Many modifications and variations may be made without departing from its spirit and scope, as will be apparent to those skilled in the art. No element, act, or instruction used in the description of the present application should be construed as critical or essential to the invention unless explicitly provided as such. Functionally equivalent methods and apparatuses within the scope of the disclosure, in addition to those enumerated herein, will be apparent to those skilled in the art from the foregoing descriptions. Such modifications and variations are intended to fall within the scope of the appended claims. The present disclosure is to be limited only by the terms of the appended claims, along with the full scope of equivalents to which such claims are entitled. It is to be understood that this disclosure is not limited to particular methods or systems.

[0362] The foregoing embodiments are discussed, for simplicity, with regard to the terminology and structure of infrared capable devices, i.e., infrared emitters and receivers. However, the embodiments discussed are not limited to these systems but may be applied to other systems that use other forms of electromagnetic waves or non-electromagnetic waves such as acoustic waves. [0363] It is also to be understood that the terminology used herein is for the purpose of describing particular embodiments only, and is not intended to be limiting. As used herein, the term "video" or the term "imagery" may mean any of a snapshot, single image and/or multiple images displayed over a time basis. As another example, when referred to herein, the terms "user equipment" and its abbreviation "UE", the term "remote" and/or the terms "head mounted display" or its abbreviation "HMD" may mean or include (i) a wireless transmit and/or receive unit (WTRU); (ii) any of a number of embodiments of a WTRU; (iii) a wireless-capable and/or wired-capable (e.g., tetherable) device configured with, inter alia, some or all structures and functionality of a WTRU; (iii) a wireless-capable and/or wired-capable device configured with less than all structures and functionality of a WTRU; or (iv) the like. Details of an example WTRU, which may be representative of any WTRU recited herein, are provided herein with respect to FIGs. 1 A-1D. As another example, various disclosed embodiments herein supra and infra are described as utilizing a head mounted display. Those skilled in the art will recognize that a device other than the head mounted display may be utilized and some or all of the disclosure and various disclosed embodiments can be modified accordingly without undue experimentation. Examples of such other device may include a drone or other device configured to stream information for providing the adapted reality experience.

[0364] In addition, the methods provided herein may be implemented in a computer program, software, or firmware incorporated in a computer-readable medium for execution by a computer or processor. Examples of computer-readable media include electronic signals (transmitted over wired or wireless connections) and computer-readable storage media. Examples of computer- readable storage media include, but are not limited to, a read only memory (ROM), a random access memory (RAM), a register, cache memory, semiconductor memory devices, magnetic media such as internal hard disks and removable disks, magneto-optical media, and optical media such as CD-ROM disks, and digital versatile disks (DVDs). A processor in association with software may be used to implement a radio frequency transceiver for use in a WTRU, UE, terminal, base station, RNC, or any host computer.

[0365] Variations of the method, apparatus and system provided above are possible without departing from the scope of the invention. In view of the wide variety of embodiments that can be applied, it should be understood that the illustrated embodiments are examples only, and should not be taken as limiting the scope of the following claims. For instance, the embodiments provided herein include handheld devices, which may include or be utilized with any appropriate voltage source, such as a battery and the like, providing any appropriate voltage.

[0366] Moreover, in the embodiments provided above, processing platforms, computing systems, controllers, and other devices that include processors are noted. These devices may include at least one Central Processing Unit ("CPU") and memory. In accordance with the practices of persons skilled in the art of computer programming, reference to acts and symbolic representations of operations or instructions may be performed by the various CPUs and memories. Such acts and operations or instructions may be referred to as being "executed," "computer executed" or "CPU executed."

[0367] One of ordinary skill in the art will appreciate that the acts and symbolically represented operations or instructions include the manipulation of electrical signals by the CPU. An electrical system represents data bits that can cause a resulting transformation or reduction of the electrical signals and the maintenance of data bits at memory locations in a memory system to thereby reconfigure or otherwise alter the CPU's operation, as well as other processing of signals. The memory locations where data bits are maintained are physical locations that have particular electrical, magnetic, optical, or organic properties corresponding to or representative of the data bits. It should be understood that the embodiments are not limited to the above-mentioned platforms or CPUs and that other platforms and CPUs may support the provided methods.

[0368] The data bits may also be maintained on a computer readable medium including magnetic disks, optical disks, and any other volatile (e.g., Random Access Memory (RAM)) or non-volatile (e.g., Read-Only Memory (ROM)) mass storage system readable by the CPU. The computer readable medium may include cooperating or interconnected computer readable medium, which exist exclusively on the processing system or are distributed among multiple interconnected processing systems that may be local or remote to the processing system. It should be understood that the embodiments are not limited to the above-mentioned memories and that other platforms and memories may support the provided methods.

[0369] In an illustrative embodiment, any of the operations, processes, etc. described herein may be implemented as computer-readable instructions stored on a computer-readable medium. The computer-readable instructions may be executed by a processor of a mobile unit, a network element, and/or any other computing device.

[0370] There is little distinction left between hardware and software implementations of aspects of systems. The use of hardware or software is generally (but not always, in that in certain contexts the choice between hardware and software may become significant) a design choice representing cost versus efficiency tradeoffs. There may be various vehicles by which processes and/or systems and/or other technologies described herein may be effected (e.g., hardware, software, and/or firmware), and the preferred vehicle may vary with the context in which the processes and/or systems and/or other technologies are deployed. For example, if an implementer determines that speed and accuracy are paramount, the implementer may opt for a mainly hardware and/or firmware vehicle. If flexibility is paramount, the implementer may opt for a mainly software implementation. Alternatively, the implementer may opt for some combination of hardware, software, and/or firmware.

[0371] The foregoing detailed description has set forth various embodiments of the devices and/or processes via the use of block diagrams, flowcharts, and/or examples. Insofar as such block diagrams, flowcharts, and/or examples include one or more functions and/or operations, it will be understood by those within the art that each function and/or operation within such block diagrams, flowcharts, or examples may be implemented, individually and/or collectively, by a wide range of hardware, software, firmware, or virtually any combination thereof. In an embodiment, several portions of the subject matter described herein may be implemented via Application Specific Integrated Circuits (ASICs), Field Programmable Gate Arrays (FPGAs), digital signal processors (DSPs), and/or other integrated formats. However, those skilled in the art will recognize that some aspects of the embodiments disclosed herein, in whole or in part, may be equivalently implemented in integrated circuits, as one or more computer programs running on one or more computers (e.g., as one or more programs running on one or more computer systems), as one or more programs running on one or more processors (e.g., as one or more programs running on one or more microprocessors), as firmware, or as virtually any combination thereof, and that designing the circuitry and/or writing the code for the software and or firmware would be well within the skill of one of skill in the art in light of this disclosure. In addition, those skilled in the art will appreciate that the mechanisms of the subject matter described herein may be distributed as a program product in a variety of forms, and that an illustrative embodiment of the subject matter described herein applies regardless of the particular type of signal bearing medium used to actually carry out the distribution. Examples of a signal bearing medium include, but are not limited to, the following: a recordable type medium such as a floppy disk, a hard disk drive, a CD, a DVD, a digital tape, a computer memory, etc., and a transmission type medium such as a digital and/or an analog communication medium (e.g., a fiber optic cable, a waveguide, a wired communications link, a wireless communication link, etc.).

[0372] Those skilled in the art will recognize that it is common within the art to describe devices and/or processes in the fashion set forth herein, and thereafter use engineering practices to integrate such described devices and/or processes into data processing systems. That is, at least a portion of the devices and/or processes described herein may be integrated into a data processing system via a reasonable amount of experimentation. Those having skill in the art will recognize that a typical data processing system may generally include one or more of a system unit housing, a video display device, a memory such as volatile and non-volatile memory, processors such as microprocessors and digital signal processors, computational entities such as operating systems, drivers, graphical user interfaces, and applications programs, one or more interaction devices, such as a touch pad or screen, and/or control systems including feedback loops and control motors (e.g., feedback for sensing position and/or velocity, control motors for moving and/or adjusting components and/or quantities). A typical data processing system may be implemented utilizing any suitable commercially available components, such as those typically found in data computing/communication and/or network computing/communication systems.

[0373] The herein described subject matter sometimes illustrates different components included within, or connected with, different other components. It is to be understood that such depicted architectures are merely examples, and that in fact many other architectures may be implemented which achieve the same functionality. In a conceptual sense, any arrangement of components to achieve the same functionality is effectively "associated" such that the desired functionality may be achieved. Hence, any two components herein combined to achieve a particular functionality may be seen as "associated with" each other such that the desired functionality is achieved, irrespective of architectures or intermedial components. Likewise, any two components so associated may also be viewed as being "operably connected", or "operably coupled", to each other to achieve the desired functionality, and any two components capable of being so associated may also be viewed as being "operably couplable" to each other to achieve the desired functionality. Specific examples of operably couplable include but are not limited to physically mateable and/or physically interacting components and/or wirelessly interactable and/or wirelessly interacting components and/or logically interacting and/or logically interactable components.

[0374] With respect to the use of substantially any plural and/or singular terms herein, those having skill in the art can translate from the plural to the singular and/or from the singular to the plural as is appropriate to the context and/or application. The various singular/plural permutations may be expressly set forth herein for sake of clarity. [0375] It will be understood by those within the art that, in general, terms used herein, and especially in the appended claims (e.g., bodies of the appended claims) are generally intended as "open" terms (e.g., the term "including" should be interpreted as "including but not limited to," the term "having" should be interpreted as "having at least," the term "includes" should be interpreted as "includes but is not limited to," etc.). It will be further understood by those within the art that if a specific number of an introduced claim recitation is intended, such an intent will be explicitly recited in the claim, and in the absence of such recitation no such intent is present. For example, where only one item is intended, the term "single" or similar language may be used. As an aid to understanding, the following appended claims and/or the descriptions herein may include usage of the introductory phrases "at least one" and "one or more" to introduce claim recitations. However, the use of such phrases should not be construed to imply that the introduction of a claim recitation by the indefinite articles "a" or "an" limits any particular claim including such introduced claim recitation to embodiments including only one such recitation, even when the same claim includes the introductory phrases "one or more" or "at least one" and indefinite articles such as "a" or "an" (e.g., "a" and/or "an" should be interpreted to mean "at least one" or "one or more"). The same holds true for the use of definite articles used to introduce claim recitations. In addition, even if a specific number of an introduced claim recitation is explicitly recited, those skilled in the art will recognize that such recitation should be interpreted to mean at least the recited number (e.g., the bare recitation of "two recitations," without other modifiers, means at least two recitations, or two or more recitations). Furthermore, in those instances where a convention analogous to "at least one of A, B, and C, etc." is used, in general such a construction is intended in the sense one having skill in the art would understand the convention (e.g., "a system having at least one of A, B, and C" would include but not be limited to systems that have A alone, B alone, C alone, A and B together, A and C together, B and C together, and/or A, B, and C together, etc.). In those instances where a convention analogous to "at least one of A, B, or C, etc." is used, in general such a construction is intended in the sense one having skill in the art would understand the convention (e.g., "a system having at least one of A, B, or C" would include but not be limited to systems that have A alone, B alone, C alone, A and B together, A and C together, B and C together, and/or A, B, and C together, etc.). It will be further understood by those within the art that virtually any disjunctive word and/or phrase presenting two or more alternative terms, whether in the description, claims, or drawings, should be understood to contemplate the possibilities of including one of the terms, either of the terms, or both terms. For example, the phrase "A or B" will be understood to include the possibilities of "A" or "B" or "A and B." Further, the terms "any of' followed by a listing of a plurality of items and/or a plurality of categories of items, as used herein, are intended to include "any of," "any combination of," "any multiple of," and/or "any combination of multiples of the items and/or the categories of items, individually or in conjunction with other items and/or other categories of items. Moreover, as used herein, the term "set" is intended to include any number of items, including zero. Additionally, as used herein, the term "number" is intended to include any number, including zero. And the term "multiple", as used herein, is intended to be synonymous with "a plurality".

[0376] In addition, where features or aspects of the disclosure are described in terms of Markush groups, those skilled in the art will recognize that the disclosure is also thereby described in terms of any individual member or subgroup of members of the Markush group.

[0377] As will be understood by one skilled in the art, for any and all purposes, such as in terms of providing a written description, all ranges disclosed herein also encompass any and all possible subranges and combinations of subranges thereof. Any listed range can be easily recognized as sufficiently describing and enabling the same range being broken down into at least equal halves, thirds, quarters, fifths, tenths, etc. As a non-limiting example, each range discussed herein may be readily broken down into a lower third, middle third and upper third, etc. As will also be understood by one skilled in the art all language such as "up to," "at least," "greater than", "less than," and the like includes the number recited and refers to ranges which can be subsequently broken down into subranges as discussed above. Finally, as will be understood by one skilled in the art, a range includes each individual member. Thus, for example, a group having 1-3 cells refers to groups having 1, 2, or 3 cells. Similarly, a group having 1-5 cells refers to groups having 1, 2, 3, 4, or 5 cells, and so forth.

[0378] Moreover, the claims should not be read as limited to the provided order or elements unless stated to that effect. In addition, use of the terms "means for" in any claim is intended to invoke 35 U.S.C. §112, 6 or means-plus-function claim format, and any claim without the terms "means for" is not so intended.

Claims

CLAIMS What is claimed is:

1. A wireless transmit/receive unit (WTRU) comprising a circuitry, including any of a transmitter, a receiver, a processor, and a memory, configured to: receive first information indicating a first time offset with respect to a first reference signal transmission; receive the first reference signal transmission; receive a second reference signal transmission; and transmit a third reference signal transmission based on the received second reference signal transmission at the first time offset with respect to the first reference signal transmission, wherein the third reference signal transmission is transmitted responsive to a power condition being satisfied.

2. The WTRU of claim 1, wherein the WTRU being configured to transmit the third reference signal transmission comprises the WTRU being configured to backscatter the second reference signal transmission.

3. The WTRU of any of claims 1 to 2, wherein the WTRU being configured to transmit the third reference signal transmission comprises the WTRU being configured to reflect an energy received from the second reference signal transmission.

4. The WTRU of any of claims 1 to 3, wherein the WTRU is configured to receive first configuration information indicating any of a reference signal sequence, a reference signal periodicity, and a number of reference signal occasions per cycle.

5. The WTRU of claim 4, wherein the first time offset corresponds to a reference signal occasion number in the cycle.

6. The WTRU of any of claims 1 to 5, wherein the first information indicates a second time offset between a first information transmission and the first reference signal transmission.

7. The WTRU of any of claims 1 to 6, wherein the third reference signal transmission is transmitted responsive to the power condition being satisfied for the received first reference signal transmission.

8. The WTRU of any of claims 1 to 7, wherein the power condition is satisfied for the received first reference signal transmission in a case where a first reference signal received power of the received first reference signal transmission is above a first threshold.

9. The WTRU of any of claims 1 to 8, wherein the third reference signal transmission is transmitted responsive to the power condition being satisfied for the received second reference signal transmission.

10. The WTRU of any of claims 1 to 9, wherein the power condition is satisfied for the received second reference signal transmission in a case where a second reference signal received power of the received second reference signal transmission is above a second threshold.

11. The WTRU of any of claims 1 to 10, wherein the first information indicates a frequency hopping pattern.

12. The WTRU of claim 11, wherein the frequency hopping pattern comprises a pattern of a plurality of sub-band indexes, wherein the first time offset is associated with an index, and wherein the WTRU is configured to determine a sub-band index from the plurality of sub-band indexes based on the index of the first time offset.

13. The WTRU of claim 12, wherein the WTRU being configured to transmit the third reference signal transmission comprises the WTRU being configured to transmit the third reference signal transmission in a sub-band associated with the sub-band index.

14. The WTRU of any of claims 1 to 13, wherein the WTRU is configured to receive second configuration information indicating a time period for performing reference signal transmissions.

15. The WTRU of claim 14, wherein the WTRU is configured to determine that the WTRU does not have enough power to perform the reference signal transmissions by an end of the time period.

16. The WTRU of claim 14, wherein the WTRU is configured to terminate performing the reference signal transmissions based on the WTRU not having enough power to perform the reference signal transmissions by an end of the time period.

17. The WTRU of claim 14, wherein the WTRU is configured to determine that the WTRU does not have enough power to perform the reference signal transmissions within a time limit before an end of the time period.

18. The WTRU of claim 14, wherein the WTRU is configured to terminate performing the reference signal transmissions based on the WTRU not having enough power to perform the reference signal transmissions within a time limit before an end of the time period.

19. A method implemented in a wireless transmit/receive unit (WTRU), the method comprising: receiving first information indicating a first time offset with respect to a first reference signal transmission; receiving the first reference signal transmission; receiving a second reference signal transmission; and transmitting a third reference signal transmission based on the received second reference signal transmission at the first time offset with respect to the first reference signal transmission, wherein the third reference signal transmission is transmitted responsive to a power condition being satisfied.

20. A method implemented in a network element, the method comprising: transmitting first information to a first wireless transmit/receive unit (WTRU), wherein the first information indicates a first time offset with respect to a first reference signal transmission of a plurality of reference signal transmissions; transmitting second information to a second WTRU, wherein the second information indicates a second time offset with respect to the first reference signal transmission, and wherein the first time offset is different from the second time offset; transmitting the plurality of reference signal transmissions; receiving from the first WTRU, a second reference signal transmission at the first time offset with respect to the first reference signal transmission; and receiving from the second WTRU, a third reference signal transmission at the second time offset with respect to the first reference signal transmission.