Method for backscatter power boost

Abstract

Methods for backscattering radio frequency (RF) signals are provided herein. A method includes receiving a transmission, the transmission including a signal and control information, the control information including power boost and repetition parameters; and determining whether an energy level of the device is sufficient to backscatter the signal in the event of a power boost. If the energy level of the device is sufficient to backscatter the received signal with a power boost, power boost is used to backscatter the received signal and modulate with a preamble. If the energy level of the device is insufficient to backscatter the received signal in the case of a power boost, the received signal is backscattered in a plurality of repetitions without a power boost and modulated with a preamble. The method comprises: receiving a reply message, the reply message comprising an indication of the preamble for modulating the backscatter signal; and transmitting information indicating an identifier or energy level of the device in response to the received reply message.

Description

Cross-reference to related applications

[0001] This application claims the benefit of U.S. Provisional Application No. 63 / 531,514, filed August 8, 2023, the contents of which are incorporated herein by reference. Background Technology

[0002] The 3rd Generation Partnership Project (3GPP) recently began research on the Internet of Things (IoT) for the environment. The goal of this research could be to investigate the feasibility of new IoT technologies opening up new markets within the 3GPP system. These new IoT technologies could potentially offer several orders of magnitude higher connection numbers and / or device density than existing 3GPP IoT technologies, and could provide several orders of magnitude lower complexity and power consumption than existing 3GPP LPWA technologies such as Narrowband (NB)-IoT and Long Term Evolution Machine Type Communications (LTE-MTC). Additionally, 3GPP has launched a research project to define various use cases for environmentally powered IoT.

[0003] Some IoT use cases may involve backscattering devices that reflect incoming radio frequency (RF) signals without generating their own RF signals. Backscattering devices can also modulate the incoming RF signal Sin(t) to transmit their own data on the reflected signal. This can be implemented using the concept of impedance mismatch. The antenna impedance ZA can be connected to the load impedance ZL at the device. The reflection coefficient can then be defined as Γ = (ZL - ZA) / (ZL ​​+ ZA). Generally, the reflected signal can be expressed as S 出 (t)=Γ×S 入 (t). Therefore, by changing the reflection coefficient over time (by adjusting the load impedance), the amplitude, frequency, etc., of the reflected signal can be altered. For example, amplitude shift keying modulation can be implemented using Γ=0 (non-reflection state / OFF signal) or Γ=1 (reflection state / ON signal). Radio frequency identification (RFID) standards can be based on backscatter communication, where the RFID tag switches the reflection coefficient between two states based on the data being transmitted. RFID tags can support ASK and PSK. Summary of the Invention

[0004] A system of one or more computers can be configured to perform specific operations or actions by installing software, firmware, hardware, or combinations thereof on the system, which, in operation, causes the system to perform actions. One or more computer programs can be configured to perform specific operations or actions by including instructions that, when executed by a data processing device, cause that device to perform actions. One general aspect includes a processor and a transceiver configured to: receive a transmission including signals and control information, the control information including power boost and repetition parameters. The processor is configured to: determine whether the energy level of the device is sufficient to backscatter a signal with a power boost. If the energy level of the device is sufficient to backscatter the received signal with a power boost, the processor and the transceiver are configured to: use a power boost to backscatter the received signal and modulate the backscattered signal with a preamble. If the energy level of the device is insufficient to backscatter the received signal with a power boost, the processor and the transceiver are configured to: backscatter the received signal in a repetitive manner without a power boost and modulate the backscattered signal with a preamble. The processor and transceiver are configured to receive a response message including an indication of a preamble for modulating the backscattered signal. The processor and transceiver are configured to transmit information indicating a device identifier and / or energy level in response to the received response message. Other embodiments of this aspect include corresponding computer systems, apparatuses, and computer programs recorded on one or more computer storage devices, each of which is configured to perform the actions of the method.

[0005] The implementation may include one or more of the following features: Power boost and repetition parameters include an indication of whether power boost is enabled or disabled, an indication of at least a first power level, and an indication of a repetition factor. If the device's energy level is sufficient to backscatter the received signal with power boost, the received signal is backscattered using power boost and modulated with a preamble. If the device's energy level is insufficient to backscatter the received signal with power boost, the received signal is backscattered multiple times at the first power level and modulated with a preamble. The indication of the preamble for modulating the backscattered signal is an indication of cyclic shift of the preamble. Control information includes an indication of at least a first preamble length and a second preamble length. The processor and transceiver are configured to modulate the backscattered signal using a second preamble length based on whether the reply message includes an indication of a preamble for modulating the backscattered signal. The processor and transceiver are configured to backscatter the received signal after a backoff period and modulate the backscattered signal with a preamble. The processor and transceiver are configured to backscatter the received signal after a delay and modulate the backscattered signal with a preamble. The delay is randomly selected from a set of configured delay values. The device is an Internet of Things (IoT) device. Implementations of the described technology may include hardware, methods, or processes, or computer software on a computer-accessible medium. Attached Figure Description

[0006] A more detailed understanding can be obtained from the following description given by way of example in conjunction with the accompanying drawings, wherein the same reference numerals in the figures denote the same elements, and wherein: Figure 1A This is a system diagram illustrating an example communication system that can implement one or more of the disclosed embodiments; Figure 1B This illustrates that, according to an embodiment, it is possible to Figure 1A The system diagram shown is of an example wireless transmit / receive unit (WTRU) used in the communication system. Figure 1C This illustrates that, according to an embodiment, it is possible to Figure 1A The system diagram shows an example radio access network (RAN) and an example core network (CN) used in the communication system shown. Figure 1D This illustrates that, according to an embodiment, it is possible to Figure 1A The system diagram shown illustrates another example RAN and another example CN used within the communication system. Figure 2 This is a diagram showing examples of two preamble sequences of different lengths; Figure 3This is an example showing a timing diagram of a signal that can be used to modulate a preamble according to one or more methods described herein; Figure 4 This is a diagram illustrating an example of a backscattering method used for preamble transmission; Figure 5 This is a diagram illustrating an example of a method used for solving race conditions; and Figure 6 This is a flowchart that further describes an example of a process for backscatter power enhancement that can be performed by an IoT device; Figure 7 This is a flowchart further describing an example of a process that can be performed by a device such as an interrogator for enabling and receiving the backscattered signal; and Figure 8 This is a flowchart illustrating another example of a process that can be performed by a device to backscatter a signal in the event of a power boost. Detailed Implementation

[0007] Figure 1A This diagram illustrates an example communication system 100 that may implement one or more of the disclosed embodiments. The communication system 100 may be a multiple access system providing content such as voice, data, video, messaging, and broadcasting to multiple wireless users. The communication system 100 enables multiple wireless users to access such content through shared system resources including wireless broadband. For example, the communication system 100 may employ one or more channel access methods, such as Code Division Multiple Access (CDMA), Time Division Multiple Access (TDMA), Frequency Division Multiple Access (FDMA), Orthogonal FDMA (OFDMA), Single Carrier FDMA (SC-FDMA), Zero-Tail Unique Word Discrete Fourier Transform Extended OFDM (ZT-UW-DFT-S-OFDM), Unique Word OFDM (UW-OFDM), Resource Block Filtered OFDM, Filter Bank Multicarrier (FBMC), etc.

[0008] like Figure 1AAs shown, the communication system 100 may include wireless transmit / receive units (WTRUs) 102a, 102b, 102c, 102d, a radio access network (RAN) 104, a core network (CN) 106, a public switched telephone network (PSTN) 108, the Internet 110, and other networks 112. However, it will be understood that the disclosed embodiments contemplate any number of WTRUs, base stations, networks, and / or network elements. Each of the WTRUs 102a, 102b, 102c, and 102d may be any type of device configured to operate and / or communicate in a wireless environment. For example, WTRUs 102a, 102b, 102c, and 102d (any of which may be referred to as a station (STA)) may be configured to transmit and / or receive wireless signals and may include user equipment (UE), mobile stations, fixed or mobile subscriber units, subscription-based units, pagers, cellular phones, personal digital assistants (PDAs), smartphones, laptops, netbooks, personal computers, wireless sensors, hotspots or Mi-Fi devices, Internet of Things (IoT) devices, watches or other wearable devices, head-mounted displays (HMDs), vehicles, drones, medical devices and applications (e.g., remote surgery), industrial devices and applications (e.g., robots and / or other wireless devices operating in the context of industrial and / or automated processing chains), consumer electronics devices, devices operating on commercial and / or industrial wireless networks, etc. Any of WTRUs 102a, 102b, 102c, and 102d may be interchangeably referred to as WTRUs.

[0009] The communication system 100 may also include base station 114a and / or base station 114b. Each of base stations 114a and 114b may be any type of device configured to wirelessly interface with at least one of WTRUs 102a, 102b, 102c, and 102d to facilitate access to one or more communication networks such as CN 106, Internet 110, and / or other networks 112. For example, base stations 114a and 114b may be base transceiver stations (BTS), Node Bs, eNodeBs (eNBs), home Node Bs, home eNode Bs, next-generation Node Bs such as gNode Bs (gNBs), new radio (NR) Node Bs, site controllers, access points (APs), wireless routers, etc. Although base stations 114a and 114b are each depicted as a single element, it will be understood that base stations 114a and 114b may include any number of interconnected base stations and / or network elements.

[0010] Base station 114a may be part of RAN 104, which may also include other base stations and / or network elements (not shown), such as base station controllers (BSCs), radio network controllers (RNCs), relay nodes, etc. Base station 114a and / or base station 114b may be configured to transmit and / or receive radio signals on one or more carrier frequencies, which may be referred to as cells (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 specific geographic area that may be relatively fixed or may change over time. A cell may also be divided into cell sectors. For example, the cell associated with base station 114a may be divided into three sectors. Therefore, in one embodiment, base station 114a may include three transceivers, i.e., one transceiver for each sector of the cell. In embodiments, base station 114a may employ multiple-input multiple-output (MIMO) technology and may utilize multiple transceivers for each sector of the cell. For example, beamforming may be used to transmit and / or receive signals in a desired spatial direction.

[0011] Base stations 114a and 114b can communicate with one or more of WTRUs 102a, 102b, 102c, and 102d via air interface 116, which can be any suitable wireless communication link (e.g., radio frequency (RF), microwave, centimeter wave, micrometer wave, infrared (IR), ultraviolet (UV), visible light, etc.). Any suitable radio access technology (RAT) can be used to establish air interface 116.

[0012] More specifically, as described above, the communication system 100 can be a multiple access system and can employ one or more channel access schemes, such as CDMA, TDMA, FDMA, OFDMA, SC-FDMA, etc. For example, base station 114a in RAN 104 and WTRUs 102a, 102b, and 102c can implement radio technologies, such as using Wideband CDMA (WCDMA) to establish Universal Mobile Telecommunications System (UMTS) Terrestrial Radio Access (UTRA) for air interface 116. WCDMA can include communication protocols such as High-Speed ​​Packet Access (HSPA) and / or Evolved HSPA (HSPA+). HSPA can include High-Speed ​​Downlink (DL) Packet Access (HSDPA) and / or High-Speed ​​Uplink (UL) Packet Access (HSUPA).

[0013] In the embodiment, base station 114a and WTRUs 102a, 102b, 102c may implement radio technologies, such as using Long Term Evolution (LTE) and / or LTE-Advanced (LTE-A) and / or LTE-Advanced Pro (LTE-A Pro) to establish Evolved UMTS Terrestrial Radio Access (E-UTRA) for air interface 116.

[0014] In the embodiments, base station 114a and WTRUs 102a, 102b, 102c may implement radio technology, such as using NR to establish NR radio access for air interface 116.

[0015] In the embodiments, base station 114a and WTRUs 102a, 102b, and 102c can implement various radio access technologies. For example, base station 114a and WTRUs 102a, 102b, and 102c can, for instance, use the dual connectivity (DC) principle to jointly implement LTE radio access and NR radio access. Therefore, the air interface used by WTRUs 102a, 102b, and 102c can be characterized by various types of radio access technologies and / or by transmissions sent to / from various types of base stations (e.g., eNBs and gNBs).

[0016] In other embodiments, base station 114a and WTRUs 102a, 102b, 102c may implement radio technologies such as IEEE 802.11 (i.e., WiFi), IEEE 802.16 (i.e., WiMAX), CDMA2000, CDMA2000 1X, CDMA2000 EV-DO, Provisional Standard 2000 (IS-2000), Provisional Standard 95 (IS-95), Provisional Standard 856 (IS-856), Global System for Mobile Communications (GSM), Enhanced Data Rate GSM Evolution (EDGE), GSMEDGE (GERAN), etc.

[0017] Figure 1ABase station 114b can be, for example, a wireless router, a home Node-B, a home eNode-B, or an access point, and can utilize any suitable RAT to facilitate wireless connectivity in localized areas such as commercial locations, homes, vehicles, campuses, industrial facilities, air corridors (e.g., for use by drones), roads, etc. In one embodiment, base station 114b and WTRUs 102c, 102d can implement radio technologies such as IEEE 802.11 to establish a wireless local area network (WLAN). In another embodiment, base station 114b and WTRUs 102c, 102d can implement radio technologies such as IEEE 802.15 to establish a wireless personal area network (WPAN). In yet another embodiment, base station 114b and WTRUs 102c, 102d can utilize cellular-based RATs (e.g., WCDMA, CDMA2000, GSM, LTE, LTE-a, LTE-a Pro, NR, etc.) to establish picocells or femtocells. Figure 1A As shown, base station 114b can be directly connected to Internet 110. Therefore, base station 114b does not need to access Internet 110 via CN 106.

[0018] RAN 104 can communicate with CN 106, which can be any type of network configured to provide voice, data, application, and / or Voice over Internet Protocol (VoIP) services to one or more of WTRUs 102a, 102b, 102c, and 102d. Data can have different Quality of Service (QoS) requirements, such as different throughput requirements, latency requirements, fault tolerance requirements, reliability requirements, data throughput requirements, mobility requirements, etc. CN 106 can provide call control, billing services, location-based services, prepaid calling, internet connectivity, video distribution, etc., and / or perform advanced security functions such as user authentication. Although... Figure 1A As not shown, but will be understood, RAN 104 and / or CN 106 can communicate directly or indirectly with other RANs that use the same RAT as or a different RAT than RAN 104. For example, in addition to connecting to RAN 104, which may be utilizing NR radio technology, CN 106 can also communicate with another RAN (not shown) using GSM, UMTS, CDMA 2000, WiMAX, E-UTRA, or WiFi radio technology.

[0019] CN 106 can also serve as a gateway for WTRUs 102a, 102b, 102c, and 102d to access PSTN 108, the Internet 110, and / or other networks 112. PSTN 108 may include a circuit-switched telephone network providing Common Old-Style Telephone Service (POTS). The Internet 110 may include a global system of interconnected computer networks and devices using common communication protocols such as Transmission Control Protocol (TCP), User Datagram Protocol (UDP), and / or Internet Protocol (IP) from the TCP / IP Internet Protocol suite. Network 112 may include wired and / or wireless communication networks owned and / or operated by other service providers. For example, network 112 may include another CN connected to one or more RANs, which may use the same RAT as RAN 104 or a different RAT.

[0020] Some or all of the WTRUs 102a, 102b, 102c, and 102d in communication system 100 may include multi-mode capabilities (e.g., WTRUs 102a, 102b, 102c, and 102d may include multiple transceivers for communicating with different wireless networks via different wireless links). For example, Figure 1A The WTRU 102c shown can be configured to communicate with a base station 114a that can use cellular-based radio technology and with a base station 114b that can use IEEE 802 radio technology.

[0021] Figure 1B This is a system diagram illustrating example WTRU 102. (See diagram below.) Figure 1B As shown, WTRU 102 may include a processor 118, a transceiver 120, a transmitting / receiving element 122, a speaker / microphone 124, a keypad 126, a display / touchpad 128, non-removable memory 130, removable memory 132, a power supply 134, a Global Positioning System (GPS) chipset 136, and / or other peripheral devices 138, etc. It will be understood that, while remaining consistent with the embodiments, WTRU 102 may include any sub-combination of the foregoing elements.

[0022] Processor 118 can be a general-purpose processor, a special-purpose processor, a conventional processor, a digital signal processor (DSP), multiple microprocessors, one or more microprocessors associated with a DSP core, a controller, a microcontroller, an application-specific integrated circuit (ASIC), a field-programmable gate array (FPGA), any other type of integrated circuit (IC), a state machine, etc. Processor 118 can perform signal encoding, data processing, power control, input / output processing, and / or any other functions that enable WTRU 102 to operate in a wireless environment. Processor 118 can be coupled to transceiver 120, which can be coupled to transmitting / receiving element 122. Although Figure 1B While the processor 118 and transceiver 120 are depicted as separate components, it will be understood that the processor 118 and transceiver 120 can be integrated together in an electronic package or chip.

[0023] Transmitting / receiving element 122 can be configured to transmit signals to or receive signals from a base station (e.g., base station 114a) via air interface 116. For example, in one embodiment, transmitting / receiving element 122 can be an antenna configured to transmit and / or receive RF signals. In embodiments, for example, transmitting / receiving element 122 can be a transmitter / detector configured to transmit and / or receive, for example, IR, UV, or visible light signals. In yet another embodiment, transmitting / receiving element 122 can be configured to transmit and / or receive both RF signals and optical signals. It will be understood that transmitting / receiving element 122 can be configured to transmit and / or receive any combination of wireless signals.

[0024] Although the transmitting / receiving element 122 is in Figure 1B While depicted as a single element, WTRU 102 may include any number of transmit / receive elements 122. More specifically, WTRU 102 may employ MIMO technology. Thus, in one embodiment, WTRU 102 may include two or more transmit / receive elements 122 (e.g., multiple antennas) for transmitting and receiving wireless signals via air interface 116.

[0025] Transceiver 120 can be configured to modulate signals transmitted by transmitting / receiving element 122 and demodulate signals received by transmitting / receiving element 122. As described above, WTRU 102 can have multi-mode capability. Therefore, transceiver 120 can include multiple transceivers for enabling WTRU 102 to communicate via various RATs (e.g., such as NR and IEEE 802.11).

[0026] The processor 118 of WTRU 102 can be coupled to and receive user input data from: a speaker / microphone 124, a keypad 126, and / or a display / touchpad 128 (e.g., a liquid crystal display (LCD) unit or an organic light-emitting diode (OLED) display unit). The processor 118 can also output user data to the speaker / microphone 124, keypad 126, and / or display / touchpad 128. Additionally, the processor 118 can access information and store data from any suitable type of memory, such as non-removable memory 130 and / or removable memory 132. Non-removable memory 130 may include random access memory (RAM), read-only memory (ROM), a hard disk, or any other type of memory storage device. Removable memory 132 may include a subscriber identity module (SIM) card, memory stick, secure digital storage (SD) card, etc. In other embodiments, the processor 118 can access information and store data from memory not actually located on WTRU 102, such as on a server or home computer (not shown).

[0027] The processor 118 may receive power from the power supply 134 and may be configured to distribute power to other components in the WTRU 102 and / or control power to those other components. The power supply 134 may be any suitable device for powering the WTRU 102. For example, the power supply 134 may include one or more dry cell batteries (e.g., nickel-cadmium (NiCd), nickel-zinc (NiZn), nickel metal hydride (NiMH), lithium-ion (Li-ion), etc.), solar cells, fuel cells, etc.

[0028] The processor 118 may also be coupled to a GPS chipset 136, which may be configured to provide location information (e.g., longitude and latitude) about the current location of the WTRU 102. In addition to or instead of information from the GPS chipset 136, the WTRU 102 may receive location information from base stations (e.g., base stations 114a, 114b) via air interface 116 and / or determine its location based on the timing of signals received from two or more nearby base stations. It will be understood that, while remaining consistent with the embodiments, the WTRU 102 may acquire location information using any suitable location determination method.

[0029] The processor 118 can also be connected to other peripheral devices 138, which may include one or more software and / or hardware modules that provide additional features, functions, and / or wired or wireless connectivity. For example, peripheral devices 138 may include accelerometers, electronic compasses, satellite transceivers, digital cameras (for photos and / or videos), Universal Serial Bus (USB) ports, vibration devices, television transceivers, hands-free headsets, Bluetooth® modules, FM radio units, digital music players, media players, video game player modules, internet browsers, virtual reality and / or augmented reality (VR / AR) devices, activity trackers, etc. Peripheral devices 138 may include one or more sensors. These sensors may be one or more of the following: gyroscopes, accelerometers, Hall effect sensors, magnetometers, orientation sensors, proximity sensors, temperature sensors, time sensors; geolocation sensors; altimeters, light sensors, touch sensors, magnetometers, barometers, gesture sensors, biometric sensors, humidity sensors, etc.

[0030] WTRU 102 may include a full-duplex radio, wherein the transmission and reception of some or all of the signals (e.g., associated with a specific subframe of both UL (e.g., for transmission) and DL (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 hardware (e.g., a choke) or signal processing via a processor (e.g., a separate processor (not shown) or via processor 118). In embodiments, WTRU 102 may include a half-duplex radio, wherein the transmission and reception of some or all of the signals (e.g., associated with a specific subframe of both UL (e.g., for transmission) or downlink (e.g., for reception)) may be concurrent and / or simultaneous.

[0031] Figure 1C This is a system diagram illustrating RAN 104 and CN 106 according to an embodiment. As described above, RAN 104 can employ E-UTRA radio technology to communicate with WTRUs 102a, 102b, and 102c via air interface 116. RAN 104 can also communicate with CN 106.

[0032] RAN 104 may include eNode-Bs 160a, 160b, and 160c, but it will be understood that RAN 104 may include any number of eNode-Bs while remaining consistent with the embodiments. eNode-Bs 160a, 160b, and 160c may each include one or more transceivers for communicating with WTRUs 102a, 102b, and 102c via air interface 116. In one embodiment, eNode-Bs 160a, 160b, and 160c may implement MIMO technology. Therefore, for example, eNode-B 160a may use multiple antennas to transmit radio signals to and / or receive radio signals from WTRU 102a.

[0033] Each of the eNode-B 160a, 160b, and 160c can be associated with a specific cell (not shown) and can be configured to handle radio resource management decisions, handover decisions, user scheduling in UL and / or DL, etc. Figure 1C As shown, eNode-B 160a, 160b, and 160c can communicate with each other via the X2 interface.

[0034] Figure 1C The CN 106 shown may include a Mobility Management Entity (MME) 162, a Serving Gateway (SGW) 164, and a Packet Data Network (PDN) Gateway (or PGW) 166. While the foregoing elements are depicted as part of CN 106, it will be understood that any of these elements may be owned and / or operated by an entity other than a CN operator.

[0035] The MME 162 can connect to each of the eNode-Bs 162a, 162b, and 162c in RAN 104 via the S1 interface and can act as a control node. For example, the MME 162 can be responsible for authenticating users of WTRUs 102a, 102b, and 102c, activating / deactivating bearers, selecting a specific serving gateway during the initial attachment of WTRUs 102a, 102b, and 102c, etc. The MME 162 can provide control plane functions for handover between RAN 104 and other RANs (not shown) employing other radio technologies such as GSM and / or WCDMA.

[0036] The SGW 164 can connect to each of the eNode Bs 160a, 160b, and 160c in RAN 104 via the S1 interface. The SGW 164 can typically route and forward user data packets to or from WTRUs 102a, 102b, and 102c. The SGW 164 can perform other functions such as anchoring the user plane during eNode-B handover, triggering paging when DL data is available to WTRUs 102a, 102b, and 102c, and managing and storing the context of WTRUs 102a, 102b, and 102c.

[0037] SGW 164 can be connected to PGW 166, which can provide WTRU 102a, 102b, 102c with access to packet-switched networks (such as Internet 110) to facilitate communication between WTRU 102a, 102b, 102c and IP-enabled devices.

[0038] CN 106 can facilitate communication with other networks. For example, CN 106 can provide WTRUs 102a, 102b, and 102c with access to circuit-switched networks (such as PSTN 108) to facilitate communication between WTRUs 102a, 102b, and 102c and traditional terrestrial line communication equipment. For example, CN 106 may include an IP gateway (e.g., an IP Multimedia Subsystem (IMS) server) or be able to communicate with such an IP gateway as an interface between CN 106 and PSTN 108. Additionally, CN 106 can provide WTRUs 102a, 102b, and 102c with access to other networks 112, which may include other wired and / or wireless networks owned and / or operated by other service providers.

[0039] Despite WTRU in Figures 1A to 1D While described as a wireless terminal, it is envisioned that, in some representative embodiments, such a terminal may (e.g., temporarily or permanently) use a wired communication interface with a communication network.

[0040] In a representative embodiment, the other network 112 may be a WLAN.

[0041] A WLAN in Infrastructure Basic Services Set (BSS) mode can have an Access Point (AP) for the BSS and one or more Stations (STAs) associated with the AP. The AP can have an interface to a Distribution System (DS) or another type of wired / wireless network that loads traffic into and / or loads traffic out of the BSS. Traffic originating outside the BSS destined for a STA can be delivered to the AP. Traffic from a STA to a destination outside the BSS can be sent to the AP for delivery to the appropriate destination. Traffic between STAs within the BSS can be sent via the AP, for example, where a source STA can send traffic to the AP, and the AP can deliver the traffic to the destination STA. Traffic between STAs within the BSS can be considered and / or referred to as point-to-point traffic. Point-to-point traffic can be sent between a source STA and a destination STA using a Direct Link Setup (DLS) (e.g., directly between them). In some representative embodiments, the DLS can use 802.11e DLS or 802.11z Tunneled DLS (TDLS). A WLAN using the Standalone BSS (IBSS) mode may not have an access point (AP), and STAs within the IBSS or using the IBSS (e.g., all STAs) can communicate directly with each other. The IBSS communication mode may sometimes be referred to as a "self-organizing" communication mode in this document.

[0042] When operating in 802.11ac infrastructure mode or a similar mode, the AP can transmit beacons on a fixed channel, such as the primary channel. The primary channel can be of fixed width (e.g., a bandwidth of 20 MHz) or dynamically configured. The primary channel can be the operating channel of the BSS and can be used by the STA to establish a connection with the AP. In some representative embodiments, Carrier Sense Multiple Access with Collision Avoidance (CSMA / CA) can be implemented, for example, in an 802.11 system. For CSMA / CA, each STA (e.g., every STA), including the AP, can sense the primary channel. If a particular STA senses / detects that the primary signal is busy and / or determines that the primary signal is busy, that particular STA can back off. In a given BSS, at any given time, only one STA (e.g., only one station) can transmit.

[0043] High-throughput (HT) STAs can communicate using a 40 MHz wide channel, for example, by combining a primary 20 MHz channel with adjacent or non-adjacent 20 MHz channels.

[0044] Very High Throughput (VHT) STAs can support channels with widths of 20 MHz, 40 MHz, 80 MHz, and / or 160 MHz. 40 MHz and / or 80 MHz channels can be formed by combining consecutive 20 MHz channels. A 160 MHz channel can be formed by combining eight consecutive 20 MHz channels, or by combining two non-consecutive 80 MHz channels, which can be referred to as an 80+80 configuration. In the 80+80 configuration, data, after channel coding, can be passed through a fragment parser that splits the data into two streams. Inverse Fast Fourier Transform (IFFT) processing and time-domain processing can be performed on each stream separately. The streams can be mapped onto the two 80 MHz channels, and the data can be transmitted by the transmitting STA. At the receiver of the receiving STA, the above operations of the 80+80 configuration can be reversed, and the combined data can be sent to the Media Access Control (MAC).

[0045] 802.11af and 802.11ah support operating modes below 1 GHz. The channel operating bandwidth and carrier are reduced in 802.11af and 802.11ah compared to those used in 802.11n and 802.11ac. 802.11af supports 5 MHz, 10 MHz, and 20 MHz bandwidths in the TV Blank (TVWS) spectrum, and 802.11ah supports 1 MHz, 2 MHz, 4 MHz, 8 MHz, and 16 MHz bandwidths using non-TVWS spectrum. According to a representative embodiment, 802.11ah may support instrument-type control / machine-type communication (MTC), such as MTC devices in macro coverage areas. MTC devices may have certain capabilities, such as limited capabilities, including support for (e.g., only) certain and / or limited bandwidths. MTC devices may include batteries with a battery life exceeding a threshold (e.g., to maintain a very long battery life).

[0046] WLAN systems that can support multiple channels and channel bandwidths (such as 802.11n, 802.11ac, 802.11af, and 802.11ah) include a channel that can be designated as the primary channel. The primary channel can have a bandwidth equal to the maximum common operating bandwidth supported by all STAs in the BSS. The bandwidth of the primary channel can be set and / or limited by the STAs operating in the BSS that support the minimum bandwidth operating mode. In the 802.11ah example, for STAs that support (e.g., only support) the 1 MHz mode (e.g., MTC type devices), the primary channel can be 1 MHz wide, 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 Sense and / or Network Allocation Vector (NAV) settings can depend on the status of the primary channel. If the primary channel is busy, for example, due to STAs (which only support the 1 MHz operating mode) transmitting to the AP, all available bands may be considered busy even if most bands remain idle.

[0047] In the United States, the available frequency band for 802.11ah is 902 MHz to 928 MHz. In South Korea, the available frequency band is 917.5 MHz to 923.5 MHz. In Japan, the available frequency band is 916.5 MHz to 927.5 MHz. The total available bandwidth for 802.11ah is 6 MHz to 26 MHz, depending on the country code.

[0048] Figure 1D This is a system diagram illustrating RAN 104 and CN 106 according to an embodiment. As described above, RAN 104 may employ NR radio technology to communicate with WTRUs 102a, 102b, and 102c via air interface 116. RAN 104 may also communicate with CN 106.

[0049] RAN 104 may include gNBs 180a, 180b, and 180c, but it will be understood that RAN 104 may include any number of gNBs while remaining consistent with the embodiments. gNBs 180a, 180b, and 180c may each include one or more transceivers for communicating with WTRUs 102a, 102b, and 102c via air interface 116. In one embodiment, gNBs 180a, 180b, and 180c may implement MIMO technology. For example, gNBs 180a and 180b may utilize beamforming to transmit signals to and / or receive signals from gNBs 180a, 180b, and 180c. Thus, for example, gNB 180a may use multiple antennas to transmit radio signals to and / or receive radio signals from WTRU 102a. In embodiments, gNBs 180a, 180b, and 180c may implement carrier aggregation technology. For example, gNB 180a can transmit multiple component carriers to WTRU 102a (not shown). A subset of these component carriers may be located on unlicensed spectrum, while the remaining component carriers may be located on licensed spectrum. In embodiments, gNBs 180a, 180b, and 180c may implement Coordinated Multipoint (CoMP) technology. For example, WTRU 102a can receive coordinated transmissions from gNBs 180a and 180b (and / or gNB 180c).

[0050] WTRUs 102a, 102b, and 102c can communicate with gNBs 180a, 180b, and 180c using transmissions associated with a scalable digital architecture. For example, the OFDM symbol spacing and / or OFDM subcarrier spacing can vary for different transmissions, different cells, and / or different portions of the radio transmission spectrum. WTRUs 102a, 102b, and 102c can communicate with gNBs 180a, 180b, and 180c using subframes of various lengths or scalable lengths, or transmission time intervals (TTIs) (e.g., containing different numbers of OFDM symbols and / or absolute times of varying durations).

[0051] gNBs 180a, 180b, and 180c can be configured to communicate with WTRUs 102a, 102b, and 102c in standalone and / or non-standalone configurations. In standalone configuration, WTRUs 102a, 102b, and 102c can communicate with gNBs 180a, 180b, and 180c without accessing other RANs (e.g., eNodeBs 160a, 160b, and 160c). In standalone configuration, WTRUs 102a, 102b, and 102c can use one or more of gNBs 180a, 180b, and 180c as mobile anchors. In standalone configuration, WTRUs 102a, 102b, and 102c can communicate with gNBs 180a, 180b, and 180c using signals in unlicensed frequency bands. In a non-standalone configuration, WTRUs 102a, 102b, and 102c can communicate / connect with gNBs 180a, 180b, and 180c while also communicating / connecting with another RAN (such as eNode-Bs 160a, 160b, and 160c). For example, WTRUs 102a, 102b, and 102c can implement DC principles to communicate substantially simultaneously with one or more gNBs 180a, 180b, and 180c and one or more eNode-Bs 160a, 160b, and 160c. In a non-standalone configuration, eNode-Bs 160a, 160b, and 160c can act as mobile anchors for WTRUs 102a, 102b, and 102c, and gNBs 180a, 180b, and 180c can provide additional coverage and / or throughput to serve WTRUs 102a, 102b, and 102c.

[0052] Each of gNBs 180a, 180b, and 180c can be associated with a specific cell (not shown) and can be configured to handle radio resource management decisions, handover decisions, user scheduling in UL and / or DL, support for network slicing, interoperability between DC, NR, and E-UTRA, routing of user plane data to User Plane Functions (UPF) 184a and 184b, routing of control plane information to Access and Mobility Management Functions (AMF) 182a and 182b, etc. Figure 1D As shown, gNB 180a, 180b, and 180c can communicate with each other via the Xn interface.

[0053] Figure 1DThe CN 106 shown may include at least one AMF 182a, 182b, at least one UPF 184a, 184b, at least one Session Management Function (SMF) 183a, 183b, and possibly a Data Network (DN) 185a, 185b. Although the foregoing elements are depicted as part of the CN 106, it will be understood that any of these elements may be owned and / or operated by an entity other than a CN operator.

[0054] AMF 182a and 182b can connect to one or more of the gNBs 180a, 180b, and 180c in RAN 104 via the N2 interface and can act as control nodes. For example, AMF 182a and 182b can be responsible for authenticating users of WTRU 102a, 102b, and 102c, supporting network slicing (e.g., handling different Protocol Data Unit (PDU) sessions with different requirements), selecting specific SMF 183a and 183b, managing registration areas, terminating Non-Access Stratum (NAS) signaling, mobility management, etc. AMF 182a and 182b can use network slicing to customize CN support for WTRU 102a, 102b, and 102c based on the service types being used by WTRU 102a, 102b, and 102c. For example, different network slices can be established for different use cases, such as services dependent on Ultra Reliable Low Latency (URLLC) access, services dependent on Enhanced Massive Mobile Broadband (eMBB) access, and services for MTC access. AMF 182a and 182b can provide control plane functions for handover between RAN 104 and other RANs (not shown) employing other radio technologies (such as LTE, LTE-A, LTE-A Pro) and / or non-3GPP access technologies (such as WiFi).

[0055] SMFs 183a and 183b can connect to AMFs 182a and 182b in CN 106 via the N11 interface. SMFs 183a and 183b can also connect to UPFs 184a and 184b in CN 106 via the N4 interface. SMFs 183a and 183b can select and control UPFs 184a and 184b, and configure traffic routing through UPFs 184a and 184b. SMFs 183a and 183b can perform other functions, such as managing and allocating UE IP addresses, managing PDU sessions, controlling policy enforcement and QoS, and providing DL data notifications. PDU session types can be IP-based, non-IP-based, or Ethernet-based.

[0056] UPF 184a and 184b can connect to one or more of the gNBs 180a, 180b, and 180c in RAN 104 via the N3 interface. These gNBs can provide WTRU 102a, 102b, and 102c with access to packet-switched networks (such as the Internet 110) to facilitate communication between WTRU 102a, 102b, and 102c and IP-enabled devices. UPF 184 and 184b can perform other functions such as routing and forwarding packets, enforcing user plane policies, supporting multihomed PDU sessions, handling user plane QoS, buffering DL packets, and providing mobility anchoring.

[0057] CN 106 can facilitate communication with other networks. For example, CN 106 may include or be able to communicate with an IP gateway (e.g., an IP Multimedia Subsystem (IMS) server) that serves as an interface between CN 106 and PSTN 108. Additionally, CN 106 can provide WTRUs 102a, 102b, and 102c with access to other networks 112, which may include other wired and / or wireless networks owned and / or operated by other service providers. In one embodiment, WTRUs 102a, 102b, and 102c can be connected to DNs 185a and 185b via UPFs 184a and 184b through their N3 interfaces and the N6 interface between UPFs 184a and 184b and local DNs 185a and 185b.

[0058] Given Figures 1A to 1D and Figures 1A to 1D The corresponding descriptions can be performed by one or more emulation devices (not shown) that perform one or more of the functions described herein with respect to: WTRU 102a to 102d, base stations 114a to 114b, eNode-B 160a to 160c, MME 162, SGW 164, PGW 166, gNB 180a to 180c, AMF 182a to 182ab, UPF 184a to 184b, SMF 183a to 183b, DN 185a to 185b, and / or any other devices described herein. An emulation device can be one or more devices configured to emulate one or more of the functions described herein. For example, an emulation device can be used to test other devices and / or simulate network and / or WTRU functions.

[0059] Simulation devices can be designed to perform one or more tests on other devices in laboratory and / or carrier network environments. For example, one or more simulation devices may perform one or more functions when fully or partially implemented and / or deployed as part of a wired and / or wireless communication network to test other devices within the communication network. One or more simulation devices may perform one or more functions when temporarily implemented / deployed as part of a wired and / or wireless communication network. Simulation devices may be directly coupled to another device for testing purposes and / or use over-the-air wireless communication to perform tests.

[0060] One or more simulation devices may perform one or more functions when implemented / deployed without being part of a wired and / or wireless communication network. For example, simulation devices may be used to test scenarios in a laboratory and / or undeployed (e.g., tested) wired and / or wireless communication networks to perform tests on one or more components. One or more simulation devices may be test equipment. Simulation devices may transmit and / or receive data using direct RF connections and / or wireless communication via RF circuitry (e.g., which may include one or more antennas).

[0061] The problems addressed by the embodiments presented in this paper can be understood as follows. Depending on the use case, the number of devices in an IoT deployment can be large. For example, thousands of such devices may be deployed in a warehouse to track assets. Efficient media access mechanisms are needed to reduce collisions and improve system efficiency. Additionally, coverage enhancement techniques may be required, as some of these devices may operate within limited coverage areas.

[0062] The following paragraphs describe the common terminology, common principles and observations, components, and common benefits of the embodiments presented herein. Hereinafter, the first device may be referred to as an "interrogator" and may be a base station (e.g., a micro or pico base station), a repeater, a UE, a WTRU, or another device communicating with the second device. The second device may be referred to as an "IoT device" or simply as a "device" or "another device."

[0063] As used herein, the term "backscattering" can refer to a transmission technique that can be used to wirelessly transmit signals. In some methods, a device can transmit a signal by applying backscattering to an incoming signal. In some examples, backscattering means receiving an incoming signal, which may (or may not) involve decoding the incoming signal to derive information or data. Backscattering can be implemented by reflecting an incoming signal. For example, unlike a conventional active transmission in which the transmitting device generates its own RF signal, a backscattering device can modulate an incoming RF wave from an external source (such as a reader) and reflect the incoming RF wave back with encoded information. The backscattered signal can be modulated by the device. The device may be able to harvest energy (e.g., from the RF signal) and store the energy in a storage unit (e.g., a capacitor). Backscattering can be useful in systems where energy efficiency is critical, such as in passive RFID systems and certain wireless sensor networks. This process can reduce power requirements because the device may not need to generate its own RF signal, but instead rely on energy from the incoming signal for both power supply and communication.

[0064] Operating a backscattering device can involve altering the impedance of the antenna to encode data onto the reflected RF signal. This modulation can be implemented using semiconductor switches that alternate between different impedance states, thereby effectively modulating the amplitude or phase of the backscattered signal depending on the modulation scheme (e.g., ASK or PSK). By manipulating these parameters, backscattering systems can efficiently transmit data over short to medium distances, making them ideal for inventory tracking, asset management, and IoT applications.

[0065] Devices capable of backscattering signals can be, for example, "passive RF devices," "semi-passive RF devices," or "active RF devices." A passive RF device can refer to any RF device that includes an antenna but lacks active components (such as antenna amplifiers) or does not amplify baseband signals for data transmission via backscattering. A passive RF device may include baseband circuitry that operates using energy induced by RF waves (making it strictly passive) or by local energy harvesting (making it semi-passive). For example, a passive RF device may not be designed to generate RF signals, which involves converting electrical energy into electromagnetic waves. Therefore, in some examples, a passive device may not include components that an active device might use, such as amplifiers, upconverters, RF links, or parts of RF links.

[0066] Semi-passive devices can be configured not to actively transmit. For example, a semi-passive device can only transmit when it is activated or receives sufficient energy to meet power requirements. Semi-active devices can include means for storing the collected energy in, for example, a battery or another type of capacitor. In a semi-active device, the means for storing the collected energy may not be used to power the transmission itself, but may be used for other purposes, such as powering a processor or other circuitry.

[0067] Active devices are those that require electricity to operate and are capable of amplifying, switching, or modifying electrical signals. Active devices perform signal processing through functions such as amplification, filtering, and conversion. These devices may be necessary for processing signals that have been converted to baseband, the frequency range occupied by the signal before it is modulated onto a carrier frequency for transmission. Unlike passive devices, which can operate without an external power source, active devices rely on external power or local energy sources such as solar cells or batteries for transmission. Common examples of active components include transistors, operational amplifiers, integrated circuits, and oscillators.

[0068] In some examples, the device as referred to herein (also referred to herein as an IoT device) can be a passive radio frequency device, a semi-passive radio frequency device, or an active device. The device can be a passive device that does not include any active components, or it can be an active device that has both a power source (e.g., an internal or external power source) and one or more active components. In some examples, the device may include both passive and active components. Those skilled in the art will understand that the methods and processes disclosed herein are not limited to a particular type of device (i.e., passive, semi-passive, or active), but can be applied to any of these types of wireless devices. The terms “backscatter,” “reflect,” and “transmit” are used interchangeably herein. As used herein, the term backscatter can be used interchangeably to refer to a combination of actions taken by the receiver, such as receiving and transmitting signals, receiving and reflecting signals, reflecting signals, or simply transmitting signals.

[0069] As used herein, the term backscattering can include or imply decoding of an incoming signal, possibly in combination with other steps mentioned above. For example, backscattering can refer to receiving, decoding, and transmitting a signal; receiving, decoding, and reflecting a signal; decoding and reflecting a signal; decoding and transmitting a signal; or simply decoding a signal.

[0070] As used herein, the term backscattering can include or imply modulation of an incoming signal, possibly in combination with other steps mentioned above. For example, backscattering can refer to receiving, modulating, and transmitting a signal; receiving, modulating, and reflecting a signal; modulating and reflecting a signal; modulating and transmitting a signal; receiving and modulating a signal; decoding, modulating, and transmitting a signal; receiving, decoding, modulating, and reflecting a signal; decoding, modulating, and reflecting a signal; decoding, modulating, and transmitting a signal; or simply modulating a signal.

[0071] In some examples, backscattering can be separate from or complement other actions taken by the device. For example, the device can be configured to receive and backscatter signals; decode and backscatter signals; backscatter and modulate signals; backscatter and transmit signals; receive, backscatter and modulate signals; receive, backscatter and reflect signals; modulate, backscatter and reflect signals; modulate, backscatter and transmit signals; receive, backscatter and modulate signals; decode, backscatter, modulate and transmit signals; receive, decode, backscatter, modulate and reflect signals; decode, backscatter, modulate and reflect signals; decode, backscatter, modulate and transmit signals; or receive, decode, backscatter, reflect, modulate and transmit signals.

[0072] In some methods, transmissions (e.g., from an interrogator to a device (e.g., an IoT device) or from a device (e.g., an IoT device) to an interrogator) can be organized into or performed within defined time intervals such as frames, time slots, or other types of time intervals. A period (e.g., a count round) can be defined as a set of time intervals in which the interrogator and device exchange messages. Some of the methods disclosed herein may still apply if transmissions are not organized into defined time intervals; however, for clarity of presentation, it can be assumed that transmissions can be performed on a frame-based basis.

[0073] One or both of the following conditions may apply. In some cases, the duration of a time interval (e.g., a frame) may not be fixed. The start of a time interval may be indicated by a predefined signal and / or message. For example, a period may be organized into frames, and the first frame may begin with the first message. This may mean that the device can determine the time interval that begins with sending a message or receiving a message (e.g., for a frame). For example, the time interval may begin with T1 + offset and end with T2, where T1 may be the time instance of the last sample of the first message, and T2 may be the time instance of the first sample of the second message. The offset may be pre-configured, configured, or determined by the device through other methods. Subsequent time intervals may begin with either the first message or the second message. It should be noted that, as mentioned above, the time interval between the first and second messages may not be defined or labeled as a “frame,” but the methods described herein may still apply.

[0074] In some cases, the duration of the time interval can have a fixed value. However, for example, for different parameter sets and / or carrier frequencies, there can be several possible duration values. The start of the time interval can be indicated by a signal and / or message.

[0075] In some methods, the device may randomly select a time interval during which it may attempt to access the channel; for example, the device may send signals and / or messages during the selected time interval to establish a communication channel with the interrogator.

[0076] In some methods, the total number of time intervals (e.g., within a period) can be predefined and / or indicated, for example, in a message (e.g., the first message of the period). The corresponding number / index of the time intervals can be indicated in the message, for example, at the start of the time interval. The number of time intervals in the first period and the second period can differ. In some methods, a 1-bit indicator can be used to indicate / point to the first time interval, for example, the first time interval in the period.

[0077] The device may transmit a preamble (e.g., a preamble for random access) within a time interval. It may also be permitted to transmit a specific type of preamble (e.g., a short or long preamble, a preamble generated at the device, or a preamble generated at the interrogator and reflected by the device) only within a specific time interval (e.g., a frame). For example, the device may anticipate or be able to transmit a short preamble in a first time interval, while the device may anticipate or be able to transmit a long preamble in a second time interval.

[0078] The m-bit code point (e.g., m=1) in the message can indicate the time interval type. The m-bit indication can be sent by time interval (e.g., within a period) or within a time interval (e.g., the first frame in a period), and can be applied to all time intervals within the same period.

[0079] One or more parameters can be included in the control message. The control message can include an identifier or flag for the first time interval in the cycle. For example, a 1-bit flag can be provided, as follows: A value of 1 indicates that the current time interval is the first time interval. A value of 0 indicates that the current frame is not the first time interval.

[0080] The control message may include an indication of the number of time intervals in the period, which may be represented by N bits. The control message may include a frame index, which may be represented by M bits. In some cases, the M bits may indicate the allowed preamble length in the current time interval, or one or more allowed preamble lengths across multiple different time intervals. This can be generalized to include preamble length / type or other attributes. If these attributes apply to all time intervals in a period (or all time intervals where preamble transmission is allowed), then the M bits can be sent in the control message at the beginning of the period.

[0081] The content of messages in the first time interval of a period can differ from that in other time intervals. For example, in some cases, only the message in the first time interval may contain a bitmap of all preambles in the period. In some examples, only the message in the first time interval may indicate the frame number in the period.

[0082] Some solutions may involve preamble backscatter power boosting. A general overview of some of these solutions can be understood as follows. A device (e.g., an IoT network device) may receive a transmission (e.g., from an interrogator). This transmission may include one or both of signaling and control information (e.g., in a message). In some cases, the interrogator may send more than one transmission including signaling and / or control information. The signal may be an unmodulated carrier (CW). The control information may include one or more of the following: an indication to enable / disable power boosting, a power boost value / level, and / or a repetition factor. Signaling and control information may be sent in separate transmissions. Control information may be received before or after the signal. The device may reflect the received signal, modulate the signal using a preamble, and use power boosting or repetition based on the device's energy level.

[0083] If the device's energy level (e.g., stored energy, battery power, etc.) is sufficient for transmission with a power boost (e.g., with an indicated power boost value / level) or above a threshold, the device can modulate the received signal (received CW) with a preamble and transmit the modulated signal using a first power level + power boost value / level (e.g., the indicated power boost value / level). The device can (e.g., randomly) select the preamble sequence and / or can (e.g., randomly) select a cyclic shift for the preamble.

[0084] If the device's energy level is insufficient to transmit with a power boost (e.g., with an indicated power boost value / level), or if the energy level is below a threshold, the device can modulate the received signal with a preamble and transmit the modulated CW multiple times for each transmission using a first power level (e.g., the device can repeat the transmission multiple times). The number of times the device transmits the modulated signal can be determined, for example, based on control information. In some cases, this number can be based on or equal to a repetition factor indicated by the control information.

[0085] The device can receive messages indicating the preamble (or cyclic shift of the preamble) used for modulation (e.g., a reply message for modulated CW). When the device receives a message indicating the preamble (or cyclic shift) used by the device, the device can send an ID and optionally the device's energy level (e.g., the device's current energy level). The use of power boost can be conditional upon control information indicating that power boost is enabled. In some cases, such as when power boost is not enabled, the device can use repetition (e.g., the device can repeat the modulated CW transmission multiple times based on an indicated repetition factor, and in some cases, a first power level can be used for each transmission).

[0086] It should be understood that energy levels can be defined based on absolute energy (e.g., joules) and / or relative energy (e.g., the ratio of energy to energy storage capacity, such as 25%, 50%, etc.). Other ways of characterizing available and / or stored energy may also be possible and can still be implemented according to the methods disclosed herein.

[0087] A multiple access scheme can be defined as a method and / or a set of procedures that can be used by an interrogator and a device (e.g., IoT devices within a group of IoT devices) to establish a communication channel that can exchange signals. Multiple access schemes are described in the following paragraphs.

[0088] One step of the process can be understood as follows: In some methods, the device can select the time interval (e.g., one of the time intervals in an inventory round) at which it may attempt to access the channel and / or establish a communication channel with the interrogator. The selection can be random; for example, the device can randomly select one of the time intervals with equal probability (from a set of time intervals). In some methods, the device can be configured and / or indicate a specific time interval. As a step in the random access process, the device can send a preamble to the interrogator. The preamble can contain at least one sequence. The sequence referred to herein can be a Zadoff-Chu sequence, an m-sequence, a Golay sequence, or another type of sequence.

[0089] In the following text, a preamble can be defined as including a cyclic prefix (CP), a sequence or k repetitions of a sequence (e.g., where k is an integer and k>1), and a guard interval (g). However, the preamble can be formed in alternative forms or formats; for example, in some cases, the preamble sequence may not have a guard interval. A carrier modulated by a preamble sequence can be referred to as a "preamble". The methods disclosed herein are still applicable if signals other than the preamble are used, such as reference signals, positioning reference signals, etc.

[0090] Figure 2 This is a diagram illustrating examples of two preamble sequences of different lengths. (See diagram for example.) Figure 2 As shown, the first preamble 210 has a first format of length t1µs and includes a cyclic prefix (CP) 211, four sequence repetitions 212a, 212b, 212c, and 212d, and a guard interval (GI) 213. The second preamble 220 has a second format of length t2µs and includes CP 221, two sequence repetitions 222a and 222b, and GI 223. In some cases, the first format may be referred to as a "long" preamble format, and the second format, which is shorter than the first format, may be referred to as a "short" preamble format.

[0091] In some methods, a device may receive an unmodulated carrier, modulate it with a preamble sequence to generate a preamble, and backscatter the preamble. The modulation format may be one of ASK, FSK, PSK, etc. In some methods, an interrogator may modulate the unmodulated carrier with a preamble sequence to generate a preamble and transmit the preamble. The device (e.g., an IoT device) may backscatter the received preamble after further processing. One difference between the preceding and subsequent methods may be that some devices may not be able to generate certain signals or may not be expected to generate certain signals. For example, some devices may not be able to generate or may not be expected to generate signals modulated with complex coefficient sequences (e.g., Zadoff-Chu sequences).

[0092] The following paragraphs can be used to understand at least one step of the process for channel access in a multiple access scheme.

[0093] Certain attributes of the preamble and / or preamble sequence can be configured and / or indicated to the device. Alternatively, attributes of the transmission of the preamble and / or preamble sequence can be configured and / or indicated to the device. Indications regarding the preamble and / or preamble sequence, or instructions regarding the transmission of the preamble and / or preamble sequence, can be included in control information within control messages sent by the interrogator. Control messages can be sent before the preamble within a defined time period (e.g., in the first frame of an inventory round and / or in each frame of an inventory round) (e.g., where there is a defined timing offset between the control message and the preamble). More than one type of control message can exist. For example, the content of a first type of message can be partially or completely different from the content of a second type of message. Alternatively or additionally, control messages can be received from a node other than the interrogator. In some methods, multiple control messages can be sent or received from different nodes.

[0094] For example, an unmodulated carrier can be transmitted before (and / or, in some methods, after) a control message to charge the device's memory cells. It should be noted that the interrogator can transmit a carrier even when it is not transmitting data or other signals on the channel, allowing the device to perform backscattering.

[0095] Control messages may include control information and may contain one or more of the following information and / or indications sent to the device. For example, a control message may indicate the start of a time interval (e.g., a frame) at which one or more devices may attempt to access the channel (e.g., send a random access preamble and / or data message). The time interval may begin at the start or end of the message, or at a predefined time interval after the start / end of the message. The device may determine the boundaries (e.g., start or end) of the time interval based on the control message.

[0096] Control messages can indicate the selection of a subset of devices. For example, the message may contain control information for selecting a subset of devices. The selected subset of devices may be allowed to attempt multiple access, for example, during the duration of a time interval or during the duration of multiple time intervals (e.g., during an inventory round). Subset selection may be based on device ID, a flag indicating maintenance is being performed on the device, device attributes, or some other information. For example, certain time intervals may be allocated for transmissions by devices with energy storage and / or power boosting capabilities.

[0097] Control messages can indicate the preamble length and / or the preamble sequence length and / or indicate attributes of length. For example, code points in the message can indicate one or more lengths (e.g., N1 seconds or symbols and N2 seconds or symbols), and / or can indicate short preambles and / or long preambles. In another example, the number of repetitions k of the sequence can be indicated.

[0098] Control messages may indicate the number of repetitions or the maximum number of repetitions of the sequence in the preamble. Control messages may include indications that the device enables / disables power boost during a time interval or a set of time intervals. Control messages may include indications of a power boost value / level (or maximum value / level) that can be applied by the device (e.g., when permitted).

[0099] Control messages may include indications of time interval indices, such as frame numbers. Control messages may include one or more delay values, or indications that one or more devices can use to determine delay values. For example, code points in the message may indicate a delay value or a set of delay values. In some examples, the message may indicate a maximum delay value, a minimum delay value (which may be assumed to be zero delay if not indicated), and the number of delay values. Using this information, the device can determine the possible set of delay values ​​as minimum delay + k * offset, where offset = (maximum delay - minimum delay) / number of delay values.

[0100] Control messages may include an indication of whether a transmission (e.g., a transmission following a control message) contains a preamble. Alternatively, the transmission may be an unmodulated carrier, which the device may anticipate being modulated to generate a preamble.

[0101] In some methods, the message may include an indication of whether the incoming signal is backscattered without modulation. For example, a bit value of 1 may indicate "backscattering without modulation," and a bit value of 0 may mean "modulated with a preamble sequence and backscattered."

[0102] Control messages may include indications of the interrogator's transmission power or indications associated with attributes of the transmission power. For example, a control message may indicate whether the transmission power can be further increased (e.g., in a future retransmission of a preamble). Alternatively, a control message may indicate the transmission power difference between this transmission and another transmission (e.g., data transmission), or whether the transmission power can be further increased (e.g., during data transmission).

[0103] Control messages may include an indication of the time gap between the message and the preamble transmission, or an attribute of the time gap. For example, an unmodulated carrier may be transmitted during this time gap.

[0104] Control messages may include an indication of the interrogator ID or an attribute of the ID, or information that can be used to identify the interrogator.

[0105] Control messages may include indications of coverage modes for a time interval or a set of time intervals. For example, a control message may include an indication of whether the device should operate in coverage enhancement mode. In some examples, long preambles may be used in coverage enhancement mode. In some examples, repetition of data messages may be used in coverage enhancement mode. In some examples, a power boost for the device may be expected in coverage enhancement mode (if such a device is capable of power boosting).

[0106] In some examples, the device can receive and decode messages, and the device can determine whether to attempt channel access. For example, the device can randomly select a time interval (e.g., a frame) from a set of available time intervals determined based on control messages and / or configuration and / or received indications. The device can select the time interval based on received signaling or configuration information or based on stored configuration. For example, it may have already received an indication to attempt channel access within the current time interval.

[0107] The device can determine an attempted access based at least on the preamble type and / or preamble attributes allowed within a time interval. For example, the device can determine an attempted channel access based on the preamble length. In some methods, if the preamble is long, it can determine an attempted channel access, and if the preamble is short, it can determine to postpone the channel access attempt. If the preamble is not an unmodulated carrier, for example, if it is a preamble signal (i.e., a signal containing a preamble), the device can determine to access the channel.

[0108] The device can also determine the time interval based on the preamble type and / or preamble attributes. For example, the device can select a first time interval for a short preamble and a second time interval for a long preamble.

[0109] Further steps in the channel access process can be understood as follows: The device may receive or determine whether to receive a preamble. The device may determine whether to attempt channel access within the current time interval (e.g., a frame). In some methods, the device may backscatter the received preamble. The device may apply a delay to the received preamble before backscattering it. The value of the delay may be randomly selected, for example, from a set of predefined delay values. In some methods, the delay value may be determined, for example, based on previous configuration, signaling, or usage. The device may be able to determine the start time of the preamble using a fixed timing offset between the message and the preamble. The delay value may be measured in seconds, in the number of symbols, or in some other duration or interval. In some methods, the delay value may be determined based on a previously selected delay value from previous channel access attempts. For example, the device may maintain the delay value for a configured time period. When the time period expires, the device may fall back to a randomly selected value.

[0110] An application with a duration or value of D for a delay can be performed as follows. The device can determine the start of the preamble. For example, during the first D seconds (assuming D is measured in seconds), the device can adjust the load impedance accordingly so that the incoming signal is not backscattered. After D seconds of the preamble signal, the device can readjust the load impedance accordingly so that the incoming signal is backscattered. The device can be configured to increase the power of the backscattered signal, for example, by applying a power boost, can receive an indication to increase the power of the backscattered signal, or can determine to increase the power of the backscattered signal. In some examples, the device can apply a cyclic shift to the preamble and then backscatter the cyclically shifted preamble.

[0111] In some methods, the application of a delay of duration or value D can be performed as follows: The device can determine the start of the preamble. The device can modulate the preamble with a modulation signal. The modulation signal can be, for example, a square wave with a specific periodicity. The device can introduce a cyclic shift or delay into the modulation signal (e.g., a square wave) and modulate the preamble with the modulation signal. The modulated preamble can then be backscattered modulated.

[0112] Figure 3 This is an example illustrating a timing diagram of a signal that can be used to modulate a preamble according to one or more methods described herein. Figure 3 In the example shown, the square wave s1(t) shown by element 310 has a periodicity of t seconds, and the duration of the square wave is eight time intervals. Square wave 310 alternates between the values ​​"0" and "1". It should be noted that in some examples, the duration of the square wave can be the same as the duration of the preamble. Figure 3 It is also shown that a cyclic shift of D=T / 2 seconds is introduced into the square wave s1(t), which produces the modulated signal s2(t) shown by element 320. The cyclic shift can be applied from the right or the left.

[0113] After multiplying the preamble with the modulation signal, the resulting signal can be backscattered. For example, in the case of OOK modulation, the portion of the preamble multiplied by the value "1" of the modulation signal can be backscattered, while the portion of the preamble multiplied by the value "0" of the modulation signal may not be backscattered. For example, the portion of the signal that is not backscattered can be absorbed by the device.

[0114] If a delay D is introduced into the modulated signal, the method described herein can be applied similarly. Cyclic shift and / or delay can be applied to the preamble and / or the signal modulated by the preamble. It should be noted that cyclic shift can be considered as a delay or advance of the signal, and the terms cyclic shift, delay, and advance are used interchangeably.

[0115] Figure 4This is a diagram illustrating an example of a method for transmitting backscatter preamble codes. Figure 4 In the diagram, the propagation of the signal over time is shown from left to right along the horizontal axis or "x" axis. The diagram shows the interrogator 410 and two devices (device 1 (in...)). Figure 4 (represented by element 420) and equipment 2 (in) Figure 4 The signal and / or message sent (represented by element 430). For example, as shown at 411, according to the embodiment described in the preceding paragraphs, the interrogator sends control messages (as shown at 311 and 317). Figure 4 As shown, interrogator 410 sends a preamble 412. Device 1 receives the preamble, applies delay D1, and performs backscattering, as shown at 421. Interrogator 410 receives the backscattered preamble and sends a reply to device 1. Device 2 receives the preamble, applies delay D2, and performs backscattering, as shown at 431. Figure 4 As shown, the interrogator 410 uses a carrier wave (CW) to transmit the preamble 412. Delays can be applied to the preamble and / or the modulated signal, as previously described.

[0116] In some methods, the device can reflect only a portion of the preamble. For example, interrogator 410 can send a first preamble sequence consisting of N symbols (1…N, 1…N) twice, and the device can reflect only a portion of the symbols (e.g., x…N, 1…x-1).

[0117] Another step in the channel access process can be understood as follows: After sending the preamble, the device can monitor the response message from the interrogator 410. The timing of the monitoring (e.g., the time when the device should monitor) can be known and / or predefined by the device.

[0118] Upon receiving a response message, the device can determine, based on the message, an indication of one or more delay values ​​D1, D2, D3, etc. For example, there can be 2^n possible D values ​​(e.g., signaled or indicated by the interrogator), and the response message can contain n bits, where each code point can indicate one of the D values. In one example, bit 00 can correspond to D0; bit 01 can correspond to D1; bit 10 can correspond to D2; and bit 11 can correspond to D3. The response message can contain an indication of one or more D values. If the indicated D value, or one of the indicated D values, matches the delay applied by the device to the preamble transmission, the device can determine that the preamble transmission (potentially) succeeded.

[0119] For example, such as Figure 4As shown, it can be assumed that device 1 applies delay D1 to the received preamble 411, and the second device applies delay D2 to the received preamble 411, and they each send delayed preambles, as shown at 421 and 431. The interrogator can estimate D1 and D2 based on the received aggregate signals 421 and 431. Interrogator 410 can indicate D1 and D2 in one or more response messages, as shown at 413 and 415, respectively. It should be noted that in some embodiments, the response message may contain a delay value, and in some embodiments, the response message may contain more than one delay value.

[0120] It should be noted that more than one device can select the same delay value and send the same delayed version of the preamble. To prevent potential collisions in subsequent communications, a race-resolution phase (described below) can be used. Alternatively or additionally, a collision may cause subsequent communications to fail, and the device may need to retransmit the preamble.

[0121] As described above, the device can receive a response message containing a delay value from the interrogator. If the delay value does not match the delay that the device has already applied to the backscatter preamble, the device can continue monitoring response messages (e.g., another response message). The device can continue comparing the delay value contained in the response message with the delay that the device has already applied to the backscatter preamble until (e.g., within a period) all response messages have been decoded.

[0122] If the delay value matches the delay that the device has already applied to the backscatter preamble, the device can send a message to the interrogator. Figure 4 In the context of this, two of these messages sent by device 1 and device 2 are shown by elements 422 and 432, respectively. Each message may contain an identifier for the corresponding device. The ID may be a random number or a number stored in the device's memory. The message may contain capability information. For example, capability information may relate to whether the device is capable of power boosting, information about the current energy level in the device's energy storage, the size of the data payload, the preferred modulation / coding scheme, or other information. In some methods, the message may contain data, such as a serial number or sensor measurement data.

[0123] The message exchange between the interrogator and the device can continue until the interrogator sends an indication to the device that the message exchange has ended, or the device sends such an indication to the interrogator. For example, the indication that the message exchange has ended can be one or more of the following: a new reply message with a new D value, an ACK, a flag toggled by the interrogator at the device, a new control message (e.g., an indication that a new frame has started), an indication from the interrogator to enter sleep mode (e.g., permanently or temporarily deactivating the device), and another message or signal.

[0124] In some methods, the interrogator can send messages to the device, such as acknowledgments. Figure 4 In the context of this, two examples of an acknowledgment message sent by interrogator 410 are shown by elements 414 and 416. The message may contain part or all of an ID sent by the device. The message, or a portion thereof, may be scrambled with the ID or a portion thereof. The message may contain scheduling information for the device. For example, the message may indicate to the device one or more time intervals (e.g., time slots or frames) to be used for data transmission.

[0125] although Figure 4 Not shown, but in some embodiments, the interrogator may send one or more "request" messages to one or more devices. The request message may contain an agreed-upon or device-sent ID. The request message may contain a request for data. For example, the request message may request a serial number, measurement, or other information. In some embodiments, the request message may not request a specific type of data, but may be an indication to the device to send data it possesses. The request message may include resource allocation information (e.g., time slot allocation or another time resource allocation) for the device to send data.

[0126] In some methods, after receiving a reply message and confirming the D value, the device can send data (e.g., serial number, measurement data, etc.) and / or device ID in the message. Figure 4 In the context of this, two examples of data messages sent by device 1 and device 2 are shown by elements 423 and 433. In some methods, acknowledgment messages (e.g., such as...) Figure 4 The confirmation messages 414 and 416 shown may include a request to send additional data (such as ID) to one or more devices.

[0127] This article describes race condition resolution. For race condition resolution, the device can send a message indicating an ID to the interrogator. To implement this, multiple sub-time intervals can be defined. For example, k sub-time intervals can be assigned after the reply message. The positions of these time intervals can be known (e.g., referenced to a predefined reply message).

[0128] Figure 5 This is a diagram illustrating an example of a method for resolving competition. It shows a system consisting of an interrogator 510 and two devices (device 1 (in...)). Figure 5 (represented by element 520) and equipment 2 (in Figure 5 The signal and / or message sent (represented by element 530). For example, as shown at 511 and 518, according to the embodiment described in the preceding paragraphs, the interrogator 510 sends a control message. Figure 5The example shown is similar; interrogator 510 sends a preamble 512. Device 1 receives the preamble, applies a delay D1, and performs backscattering, as shown at 521. Interrogator 510 receives the backscattered preamble and sends a reply to device 1, shown at 513. Figure 5 In the example shown, device 2 receives preamble 512, applies a delay equal to D1, and performs backscattering, as shown at 531. Because the same delay value D1 is applied to backscattering preambles 521 and 531, collisions or races may occur between the backscattering preambles.

[0129] The device can (e.g., randomly) select one or more sub-time intervals and send ID messages within the selected sub-time intervals. The number of sub-time intervals can be indicated by the interrogator, for example, in a reply message or control message. Figure 5 As shown, there can be two sub-time intervals 501 and 502. Device 1 sends ID message 522 in the first sub-time interval 501, and device 2 sends ID message 532 in the second sub-time interval 502. Messages 522 and 532 may each contain an ID, a portion of the ID, and / or other data.

[0130] Similar to what has been described in the preceding paragraphs, the interrogator 510 can send messages to acknowledge messages 522 and 532, such as Figure 5 The data are shown at 514 and 515 respectively. Devices 520 and 530 can each send data, as shown at 523 and 533, which can be acknowledged by an interrogator, as shown at 516 and 517. In some embodiments, as shown at 516 and 517, the interrogator can acknowledge data 523 and 533 sent by device 1 and device 2.

[0131] This article describes a method involving the use of multiple D values. In some methods, the response message sent by the interrogator may include multiple D values ​​of multiple detected preambles. A device that receives a message including D values ​​can determine that the preamble it sent may have been received.

[0132] In such cases, the response message may include scheduling information for the device sending the preamble with a delay corresponding to the D value. Alternatively or additionally, the device may determine the time interval for sending messages based on the order of the D values ​​in the response message. For example, a device sending the preamble with a delay corresponding to a first D value in the response message may use a first time slot to send the ID, and a device sending the preamble with a delay corresponding to a second D value in the response message may use a second time slot to send the ID.

[0133] In some methods, the interrogator can use the D value as the device ID to send a scheduling message. For example, the message could contain the D value and a request for data. The device that receives the message and acknowledges the D value can access the channel and send the requested data.

[0134] Further steps in the channel access process can be understood as follows. If the device does not receive a reply message indicating the first delay value to be used by the device (e.g., corresponding to a preamble of length L1), the device may perform one or more steps as described in the following paragraphs.

[0135] If the device does not receive a response message indicating the first delay value used by the device (corresponding to a preamble of length L1), the device may transmit a second preamble of length L1 (e.g., CW modulated by a second preamble of length L1) in the event of a power boost. For example, the device may apply a first power level plus a power boost level or value to transmit the second preamble of length L1. In some methods, the device may potentially transmit the second preamble of length L1 after a backoff period (e.g., in the next cycle). Transmitting the second preamble in the event of a power boost may depend on the device's energy level (e.g., stored energy, battery charge, etc.) being sufficient for transmission in the event of a power boost (e.g., greater than a threshold). Alternatively or additionally, the transmission of the second preamble may depend on whether a power boost is permitted (or explicitly disallowed). The power boost level or value, or the difference between the first power level and the power level when the power boost is applied, may be signaled by an interrogator or predetermined or determined by the device. If some or all of the conditions for transmitting the second preamble in the event of a power boost are not met, the device may, for example, not transmit the second preamble, transmit the second preamble without a power boost, or transmit a second preamble with a different L2 length. Further details regarding the transmission of the second preamble are provided in the following paragraphs.

[0136] The time interval (e.g., frame) for sending the preamble can be randomly selected. The selected time interval can be a time interval that supports a preamble length L1 (which can be sent as a signal in a control message).

[0137] The device can determine the backoff parameters according to one or more of the following methods. In some cases, the backoff period or time can be selected as any time interval (e.g., a frame) within the same period or another period (e.g., the next period). In some cases, the device may receive a control message within a period indicating that backoff has been completed (for one or all devices). After receiving this message, the device can randomly select a time interval from the remaining time intervals. In some cases, a specific time interval for retry is indicated, for example, in a control message such as a reply message.

[0138] In some embodiments, if the device does not receive a response message indicating a first delay value (corresponding to a preamble of length L1) used by the device, and if the device's energy level (e.g., stored energy, battery power, etc.) is insufficient for transmission with a power boost (e.g., below a threshold), the device may transmit a preamble of length L2 (e.g., a CW modulated by a preamble of length L2). In some embodiments, L2 may be greater than L1, but it should be understood that in other embodiments, L2 may be equal to or less than L1. The device may transmit a preamble of length L2 without a power boost (e.g., using a first power level). In some embodiments, if a power boost is disabled (e.g., indicated as disabled by a control message), the device may transmit a preamble of length L2 without a power boost, regardless of the device's energy level.

[0139] Control information may include an indication of whether preamble length L2 is used / allowed in one or more time intervals (e.g., frames), and the device may randomly select one of the time intervals that supports L2.

[0140] The determination of whether a device should use a power boost and / or a longer preamble can be performed as follows. The device can transmit a second preamble of length L1 (e.g., a CW modulated by a second preamble of length L1) in the case of a power boost. For example, the device can apply a first power level plus a power boost level or value to transmit a second preamble of length L1. If a power boost is permitted (or not explicitly prohibited), the device can transmit the second preamble in the case of a power boost. Transmitting the second preamble in the case of a power boost can depend on the device's energy level (e.g., stored energy, battery charge, etc.) being sufficient for transmission in the case of a power boost (e.g., energy level greater than a threshold). The power boost level or value, or the difference between the first power level and the power level when the power boost is applied, can be transmitted by a signal from an interrogator, or predetermined or determined by the IoT device. If some or all of the conditions for transmitting the second preamble in the case of a power boost are not met, the device can, for example, not transmit the second preamble, transmit the second preamble without a power boost, or transmit a second preamble with a different length L2.

[0141] This paper provides a general description of solutions utilizing orthogonal preambles. In some methods, a device (e.g., an IoT device) (e.g., from an interrogator) receives a transmission that includes signals and control information (e.g., in a message). The control information may be received before the signals.

[0142] Control information may include one or more of the following: an indication of the start or start time of a first time interval (e.g., the start or start time of a frame or time slot), an indication of enabling / disabling power boost, a power boost value / level, and a preamble length (e.g., a first preamble length L1). The signal may include a first preamble (e.g., a carrier (CW) modulated with a first preamble). The length of the preamble may be the first preamble length L1. The preamble may include a cyclic prefix and one or more repetitions of the sequence. The preamble may be consistent with the description provided in the preceding paragraphs.

[0143] In some methods, the device may transmit the received signal after applying a delay of a first value (e.g., by backscattering or reflection). The device may begin transmitting the received signal from a time corresponding to the start of an indication of a first time interval (or start time) plus the first delay value. The device may, for example, randomly select the first delay value from a set of values ​​that can be configured, known, or received (e.g., from an interrogator), or select it according to a non-random method (e.g., based on one or more deterministic, configured, or pre-configured criteria that the device can evaluate).

[0144] In some embodiments, the device may receive a response message that indicates a first delay value used by the device. When the device receives the response message indicating the first delay value used by the device, the device may (e.g., send an ID associated with the device to an interrogator).

[0145] In some embodiments, the device may send the ID within a second time interval. The device may select the second time interval from a set of time intervals (e.g., which may be known or configured) after receiving a reply message (e.g., after the time or time unit of reception, such as after the start or end time or time unit of reception).

[0146] If the device does not receive a response message indicating the first delay value used by the device, the device may perform one or more of the following steps. In some steps, if the device's energy level (e.g., stored energy, battery power, etc.) is sufficient for transmission with a power boost (e.g., greater than a threshold), the device may transmit a second preamble of length L1 (e.g., a CW modulated by a second preamble of length L1) with a power boost (e.g., using a first power level plus a power boost level or value). In some steps, if the device's energy level (e.g., stored energy, battery power, etc.) is insufficient for transmission with a power boost (e.g., below a threshold), the device may transmit a preamble of length L2 (e.g., a CW modulated by a preamble of length L2). L2 may be greater than L1, but it should be understood that in some embodiments, L2 may be equal to or less than L1. The device may transmit a preamble of length L2 without a power boost (e.g., using a first power level).

[0147] In some steps, if power boost is disabled (e.g., indicated as disabled by a control message), the device can send a second-length L2 preamble without power boost, regardless of the device's energy level. If the device sends an ID, it can receive an acknowledgment message confirming receipt of the ID. For example, the acknowledgment message may contain the ID or a portion of it.

[0148] In some embodiments, if the device sends an ID but does not receive an acknowledgment message confirming receipt (e.g., the acknowledgment message does not contain the ID or a portion of the ID, or the device does not receive any acknowledgment message), the device may send (e.g., backscatter or reflect) a preamble of length L1 (e.g., a second or third preamble, such as a CW modulated with a preamble of length L1).

[0149] In some methods, the device can receive messages (e.g., containing control information), and the device can receive an unmodulated carrier. The device can modulate the carrier with a preamble sequence and backscatter the modulated carrier.

[0150] A preamble sequence (also referred to herein simply as a “sequence”) may include one or more of the following: a cyclic prefix, a sequence or repetition of a sequence, and a guard interval. One or more coefficients of the sequence (e.g., a symbol) may be 1 and -1 (or 1 and 0). In some embodiments, the device may select a preamble sequence from a set of possible preamble sequences (e.g., randomly). In some embodiments, the preamble sequence may already be stored at the device (e.g., during manufacturing). A sequence or a set of sequences may be available at the device (e.g., stored in memory), and the device may generate a preamble sequence, for example, by applying a specific number of repetitions to the sequence, adding a cyclic prefix, and a guard interval. The device may (e.g., randomly) select a preamble, or may (e.g., randomly) select a cyclic shift for the preamble. The terms “preamble index” and “cyclic shift index” are used interchangeably.

[0151] In some methods, the device can send a preamble sequence and / or multiple repetitions of that sequence, for example, to enhance coverage. In some methods, the device can adjust the symbol duration. For example, in one case, the symbol duration of the preamble can be equal to t1 (e.g., duration equal to t1 seconds), and in another case, the symbol duration can be equal to t2 (e.g., t2 seconds). In some methods, the symbol duration can be defined based on a clock signal. For example, the symbol duration can be represented by a variable M, where M = 2 clock symbols, or M = 4 clock symbols, etc., and one of the clock symbols can correspond to a square wave. In some methods, a longer symbol duration can be used to enhance coverage.

[0152] In some methods, the control message may indicate one or more of the following: the maximum number of repetitions that the device can apply, the number of repetitions that the device can apply, or the symbol length (e.g., based on a multiple M of the clock signal).

[0153] In some methods, the device can determine to send the preamble in enhanced coverage mode. For example, in the first transmission, the interrogator may not detect the preamble (e.g., the device may not receive a reply message), and in the second transmission, the device can make the determination to send in enhanced coverage mode.

[0154] In some methods, if the energy level of the device (e.g., stored energy, battery power, etc.) is sufficient for transmission with a power boost (e.g., sending a preamble with an indicated power boost value / level) or is above a threshold, the device can modulate the received signal (i.e., the received CW) with a preamble and transmit the modulated signal using a first power level while simultaneously applying or adding a power boost value / level (e.g., the indicated power boost value / level).

[0155] The determination of whether to increase power can be based on one or more of the following. For example, the determination of whether to increase power can be based on whether the device has sufficient power in memory for power boosting. The determination of whether to increase power can be based on whether the device has received control information enabling and / or instructing power boosting and / or repetition. The determination of whether to increase power can be based on whether a previous random access attempt was successful or unsuccessful. The determination of whether to increase power can be based on priority relative to other techniques or processes. For example, power boosting may have a higher priority than another technique (such as repetition or the use of longer symbols) (e.g., the device may apply power boosting before relying on repetition based on some defined set of rules or received configuration or instructions).

[0156] During the initial random access attempt, the device can apply the M value and / or repetition count indicated in the control message. If random access is unsuccessful, the IoT device can retransmit the preamble at another time interval. In some methods, retransmission can potentially be performed in another cycle or in the same cycle after the backoff period. This can be configured or enabled / disabled by the interrogator. In such an attempt (i.e., during retransmission), if the device has sufficient power, it can also increase the power; if it does not have sufficient power, it can increase M and / or the repetition count.

[0157] The methods described in previous chapters may be applicable, except that in this method, the device can generate a preamble, generate multiple repetitions of the signal and / or message, and / or change the modulation scheme to transmit a symbol for a longer or shorter duration. For example, when the modulation scheme changes, the symbol duration may be longer or shorter depending on the scheme.

[0158] In some methods, the device can send data and / or messages to the interrogator without first sending a preamble. The device can select a time interval (e.g., randomly select frames from among allowed frames) and can perform one or more of the following steps. For example, the device can send a message that may contain at least one of an ID and user data (e.g., sensor measurements). The device can then monitor an acknowledgment message. The acknowledgment message can contain part or all of the ID. Attributes of the acknowledgment message can be defined by part or all of the ID. For example, a CRC included in the acknowledgment message can be scrambled using part or all of the ID.

[0159] The device can send a message that may contain at least user data (e.g., measurements from one or more sensors). The device can then monitor acknowledgment messages. Acknowledgment messages can contain part or all of the user data. One attribute of the acknowledgment message can be defined by part or all of the user data. For example, CRC can be used to scramble a portion of the user data (e.g., the last N bits of the data). Acknowledgment messages may include a request for additional data transmission from the device (e.g., user ID).

[0160] The determination of whether to send a preamble can be based on, for example, configuration, signaling, or indication received in a control message. For instance, a control message in the first time interval of a period (e.g., a frame) can enable / disable preamble transmission. In some examples, preamble transmission can be enabled / disabled in each time interval (e.g., a frame) or each set of time intervals within a period. In some examples, the type of preamble can be indicated in each time interval or each set of time intervals within a period: the first N / 4 time intervals can be allocated to a backscatter preamble, the second N / 4 time intervals can be allocated to a generated preamble, and / or the last N / 2 time intervals can be allocated to a transmission without a preamble.

[0161] Some of the solutions described in this article may involve coverage enhancement.

[0162] In some embodiments, a first device (e.g., an interrogator device or a WTRU) receives configuration information from a network node (e.g., a base station or a NodeB (e.g., a gNB)). This configuration information includes one or more of the following: the maximum transmission power of the first device toward one or more other devices (e.g., which may be a type of device such as an IoT device); the maximum transmission power of one or more other devices; an indication of whether power boosting is allowed or enabled (e.g., for one or more other devices); a signal quality / strength threshold; a maximum number of repetitions (e.g., for one or more other devices); and a power-saving priority (e.g., for one or more devices).

[0163] A first device may transmit a first transmission at a first transmission power to at least a second device (e.g., a device among one or more other devices, or a device of one or more other device types). The first device may receive a second transmission from the second device. The second transmission may include a modulated carrier and / or a preamble (e.g., the received second transmission may be a reflection or backscatter of the first transmission). The received second transmission may include information about whether the second device supports power boosting and / or whether the second device applies power boosting to the second transmission. The first device may determine (e.g., measure or estimate) the quality or strength of the received signal, such as the RSRP of the received second transmission.

[0164] In some examples, if the determined signal quality or strength is below a signal quality / strength threshold, the first device may perform one or more of the following: The first device may determine a power margin as the difference between the maximum transmission power of the first device toward one or more other devices and a first transmission power. If the power margin is above the threshold (i.e., if there is sufficient margin), the first device may determine a second transmission power higher than the first transmission power and may use the determined second transmission power to send a third transmission (e.g., a carrier and / or a preamble) to the second device. If the power margin is below the threshold (i.e., there is insufficient margin), the first device may send a transmission to the second device, thereby indicating an increase in power and / or indicating the number of repetitions for the transmission.

[0165] In some examples, the first device may determine whether to increase its power used for transmission or instruct the second device to increase its transmission power or use repetition. This determination may be based on one or more of received configuration information and / or the size of the payload to be transmitted by the second device. If the first device determines to increase its power used for transmission, it may determine a second transmission power higher than the first transmission power and use the determined second transmission power to transmit a third transmission (e.g., a carrier and / or a preamble) to the second device. If the first device determines to instruct increased power and / or use repetition, it may transmit a transmission to the second device, thereby instructing increased power and / or instructing the number of repetitions used for transmission.

[0166] In some methods, the interrogator may receive configuration information from the network. For example, if the interrogator is a WTRU, it may receive configuration information from a base station (e.g., a NodeB, such as a gNB). The configuration information may include, but is not limited to, one or more of the following: the maximum transmission power of the interrogator toward one or more other devices that may be a type of device (such as an IoT device); the interrogator's total maximum transmission power; the maximum transmission power of one or more devices; an indication of whether power boosting is allowed or enabled (e.g., for one or more other devices); signal quality / strength thresholds (e.g., including RSRP, SNR, SINR, etc.), which can be measured based on signals received from the devices; the maximum number of repetitions and / or repetitions applicable to the device transmitting signals and / or transmitting on the channel (e.g., for one or more other devices); and a priority level associated with the interrogator and / or the devices. In some methods, the priority level may characterize the priority or relative priority of energy saving. For example, energy saving at a device may have a higher priority than energy saving at the interrogator. Based on the priority, the interrogator may determine one or more transmission parameters, such as the transmission power of the interrogator and / or the devices.

[0167] In some methods, priority can be determined by the interrogator, for example, based on one or more rules. In some examples, the device can always have higher priority. In some examples, the device may only have higher priority if the interrogator's energy level is above a certain level. In some examples, the device may only have higher priority if its energy level is below a certain level.

[0168] Essentially as described in the paragraphs above, energy levels can be defined based on absolute energy (e.g., joules) and / or relative energy (e.g., the ratio of energy to energy storage capacity, such as 25%, 50%, etc.). Other ways of characterizing available and / or stored energy may also be possible and can still be implemented according to the methods disclosed herein.

[0169] In some methods, the interrogator may send a first transmission at a first transmission power to at least a second device (e.g., an IoT device among one or more other devices, or a device of one or more other device types). The first transmission may be the transmission of an unmodulated carrier, a preamble (e.g., a preamble backscattered by an IoT device as previously discussed), a reference signal, a message, or another type of signal.

[0170] The interrogator can receive a second transmission from the device. The second transmission may include a reflection or backscatter of the modulated carrier and / or the first transmission (e.g., a reference signal transmitted by the interrogator and backscattered by the device). The received second transmission may include information about whether the second device supports power boosting and / or whether power boosting is applied to the second transmission. The received second transmission may include attributes of the energy level at the device's memory. For example, this attribute may be the ratio of available energy to storage capacity and / or total storage capacity.

[0171] In some methods, the interrogator can determine (e.g., measure or estimate) the quality or strength of the received signal, such as the RSRP of a received second transmission.

[0172] In some methods, the interrogator can increase and / or determine to increase the transmission power toward one or more devices. This determination can be based on one or more conditions, which may include, but are not limited to, at least one of those conditions described in the following paragraphs.

[0173] In some methods, the interrogator can determine the power margin as the difference between the maximum transmit power and a reference transmit power, where the reference transmit power can be, for example, the transmit power applied to the signal backscattered by the IoT device and used for RSRP measurement at the interrogator. The reference transmit power can be the last transmit power applied. The reference transmit power can also be the transmit power applied within a specific time interval.

[0174] In some methods, the interrogator can compare the power margin with a threshold. The threshold can be configured by the network. If the difference is greater than zero, the interrogator can determine a new transmission power, for example, p = p_reference + p_offset. The value of p_offset can be configured and / or indicated by the network.

[0175] In some methods, the interrogator can determine priorities (e.g., energy-saving priorities) and can determine that one or more devices have higher priorities. The interrogator can increase and / or determine to increase the transmission power toward one or more devices based on the priorities of the interrogator and / or one or more devices.

[0176] In some methods, if the energy stored at the device is below a threshold, or equal to or below a threshold, the interrogator can increase and / or determine to increase the transmission power toward one or more devices.

[0177] In some methods, if the time required for the energy stored at the device to reach a certain level exceeds a threshold, or is equal to or greater than a threshold, the interrogator can increase and / or determine to increase the transmission power toward one or more devices.

[0178] In some methods, the interrogator can estimate the number of devices. In other methods, the number of devices counted after one or more cycles (e.g., the number of devices that communicate with the interrogator and send some data, such as serial numbers) may be less than the estimated number. This could mean that some devices are unable to access the channel, for example, due to collisions and / or coverage issues. The interrogator can increase transmission power until all devices have been counted and / or until the estimated number of devices to be counted is zero or below a threshold.

[0179] In some methods, the interrogator can determine whether to request and / or instruct the device to increase or boost its transmission power. This determination can be based on one or more conditions, which may include, but are not limited to, at least one of the following: One condition may be that the interrogator has reached its maximum transmission power. The power boost request / instruction may be sent to a group of devices in a public message. Devices receiving the message / instruction may apply the increased power to their transmission. The increased transmission power may be applied until the energy level drops below a threshold. The amount of the power increase may be indicated to the IoT device.

[0180] The interrogator can request the device to increase power and / or use repeating and / or longer symbols (i.e., apply a different MCS). The device can send its energy level in the message. If the energy level is above a threshold, the interrogator can request the device to use a power boost. The interrogator can signal the device to charge its storage units (e.g., capacitors). For example, a 1-bit value can signal the device that a CW will be sent within the next kiloms or until the next message. This signal can instruct the device to stop monitoring the channel and recharge its energy storage units.

[0181] Figure 6 This is a flowchart further describing an example of a process that can be performed by the device for backscattering signals. For example... Figure 6 As shown, at 610, the device receives at least one transmission, which includes signals (e.g., CW) and / or control information. The control information may include, for example, an indication to enable or disable power boost, an indication of a power boost value, and one or more of a repetition factor; however, it should be understood that... Figure 6 The control information mentioned may include the control information discussed in any of the embodiments mentioned above. As shown at 620, the device may backscatter (i.e., reflect) the received signal while modulating the signal using parameters based on the device's energy level. For example, if the device's energy level is sufficient for power boosting or above a threshold, the device may use power boosting to reflect the signal. In some examples, if the device's energy level is insufficient for power boosting or below a threshold, the device may reflect the signal multiple times. The parameters used to modulate the signal may be one of a preamble and a cyclic shift. As shown at 630, the device may receive a message (e.g., a reply to the backscattered signal) that includes an indication of the parameters used by the device to modulate the backscattered signal. The indication of the parameters used by the device to modulate the reflected signal can serve as an acknowledgment of the backscattered signal.

[0182] Figure 7 This is a flowchart illustrating an example of a process that can be performed by a device such as an interrogator to enable and receive a backscatter signal. Figure 7As shown, at 710, the interrogator sends at least one transmission, which includes a signal (e.g., CW) and / or control information. The control information may include, for example, an indication to enable or disable power boost, an indication of a power boost value, and one or more repetition factors. Subsequently, as shown at 720, the interrogator may receive a repetition of at least one backscatter (i.e., reflection) of its previously transmitted signal. The backscatter signal may be modulated based on given parameters (such as a preamble sequence). As shown at 730, the interrogator may send a message (e.g., a reply to the backscatter signal) including an indication of parameters used by the device to modulate the backscatter signal. The indication of parameters used by the device to modulate the reflected signal can serve as an acknowledgment of the backscatter signal.

[0183] Figure 8 This is a flowchart illustrating another example of a process that can be performed by a device for backscattering a signal in the event of a power boost. (e.g.) Figure 8 As shown, at 810, the device receives a transmission that includes signals (e.g., CW) and / or control information. The control information may include, for example, power boost parameters and repetition parameters, but it should be understood that... Figure 8 The control information mentioned may include the control information discussed in any of the embodiments mentioned above. As shown at 820, the device determines whether the device's energy level is sufficient to backscatter the received signal in the event of a power boost.

[0184] The device can backscatter (i.e., reflect) the received signal while modulating the signal using parameters based on the device's energy level. For example, as shown at 830a, if the device's energy level is sufficient, the device can use power boosting to backscatter the received signal and modulate the backscattered signal with a preamble. It should be noted that, generally, the device can modulate the backscattered signal with a baseband signal, which can be a preamble, a data signal, etc. The methods described herein (e.g., the disclosed power boosting method) are similarly applicable to baseband signals other than a preamble. As shown at 830b, if the device's energy level is insufficient, the device can backscatter the received signal multiple times without applying power boosting and modulate the backscattered signal with a preamble. At 840, the device can receive a message (e.g., a reply to the backscattered signal) including an indication of the parameters used by the device to modulate the backscattered signal. The indication of the parameters used by the device to modulate the reflected signal can serve as confirmation of the backscattered signal. At 850, the device can send a response to the received reply message, which includes the device's identifier and / or an indication of the energy level.

[0185] Although the features and elements have been described above in specific combinations, those skilled in the art will understand that each feature or element can be used alone or in any combination with other features and elements. Furthermore, the methods described herein can be implemented in a computer program, software, or firmware incorporated into a computer-readable medium for execution by a computer or processor. Examples of computer-readable media include electronic signals (transmitted via a wired or wireless connection) and computer-readable storage media. Examples of non-transitory computer-readable storage media include, but are not limited to, read-only memory (ROM), random access memory (RAM), registers, cache memory, semiconductor memory devices, magnetic media such as internal hard disks and removable disks, magneto-optical media, and optical media such as CD-ROM discs and digital multifunction disks (DVDs). The processor associated with the software can be used to implement a radio frequency transceiver for a WTRU, UE, terminal, base station, RNC, or any host computer.

Claims

1. An apparatus, the apparatus comprising: Processor and transceiver; The processor and the transceiver are configured to receive transmissions, the transmissions including signals and control information, the control information including power boost and repetition parameters; The processor and the transceiver are configured to backscatter the received signal and modulate the backscattered signal with a preamble. The processor and the transceiver are configured to backscatter the received signal when the device's energy level is sufficient to backscatter the signal with increased power. Furthermore, the processor and the transceiver are configured to: under the condition that the energy level of the device is insufficient to backscatter the received signal with a power boost, backscatter the received signal multiple times without a power boost and modulate the backscattered signal with a preamble; The processor and the transceiver are configured to: receive a response message, the response message including an indication of the preamble for modulating the backscattered signal; and The processor and the transceiver are configured to send information indicating the device's identifier or energy level in response to a received reply message.

2. The device according to claim 1, wherein, The control information includes: an indication to enable or disable the power boost of the device, an indication of at least a first power level, and an indication of a repetition factor.

3. The device according to claim 2, wherein, When the energy level of the device is insufficient to backscatter the received signal with increased power, the processor and the transceiver are configured to backscatter the received signal multiple times at the first power level and modulate the backscattered signal with a preamble.

4. The device according to claim 1, wherein, The indication of the preamble used to modulate the backscattered signal is an indication of the cyclic shift of the preamble.

5. The device according to claim 1, wherein, The control information includes indications of at least the first preamble length and the second preamble length.

6. The apparatus of claim 5, wherein the processor and the transceiver are configured to modulate the backscattered signal using the second preamble length based on receiving a reply message including an indication of the preamble for modulating the backscattered signal.

7. The device of claim 1, wherein the processor and the transceiver are configured to: backscatter the received signal after a backoff period, and modulate the backscattered signal with a preamble.

8. The device of claim 1, wherein the processor and the transceiver are configured to: after a delay, backscatter the received signal and modulate the backscattered signal with a preamble.

9. The device according to claim 8, wherein, The delay is randomly selected from a set of configured delay values.

10. The device according to claim 1, wherein, The device is an Internet of Things (IoT) device.

11. A method for backscattering radio frequency (RF) signals, the method comprising: Receive transmission, the transmission including signals and control information, the control information including power boost and repetition parameters; Determine whether the energy level of the device is sufficient to backscatter the signal under power enhancement; When the energy level of the device is sufficient to backscatter the received signal with power boost, the received signal is backscattered using power boost and the backscattered signal is modulated with a preamble; Receive a response message, the response message including an indication of the preamble for modulating the backscattered signal; as well as In response to a received reply message, information indicating the device's identifier or energy level is sent.

12. The method according to claim 11, wherein, When the energy level of the device is insufficient to backscatter the received signal with a power boost, the received signal is backscattered multiple times without a power boost and the backscattered signal is modulated with a preamble.

13. The method according to claim 12, wherein, The power boost and repetition parameters include: an indication to enable or disable the power boost of the device, an indication of at least a first power level, and an indication of a repetition factor.

14. The method according to claim 12, wherein, When the energy level of the device is insufficient to backscatter the received signal with increased power, the received signal is backscattered multiple times at the first power level and the backscattered signal is modulated with a preamble.

15. The method according to claim 11, wherein, The indication of the preamble used to modulate the backscattered signal is an indication of the cyclic shift of the preamble.

16. The method according to claim 11, wherein, The control information includes indications of at least the first preamble length and the second preamble length.

17. The apparatus of claim 16, wherein the processor and the transceiver are configured to modulate the backscattered signal using the second preamble length based on whether a reply message including an indication of the preamble for modulating the backscattered signal is received.

18. The apparatus of claim 11, wherein the processor and the transceiver are configured to: backscatter the received signal after a backoff period and modulate the backscattered signal with a preamble.

19. The apparatus of claim 11, wherein the processor and the transceiver are configured to: after a delay, backscatter the received signal and modulate the backscattered signal with a preamble.

20. The device according to claim 19, wherein, The delay is randomly selected from a set of configured delay values.

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