Method for targeted wake-up and 802.11 frame extension for energy harvesting

Abstract

A method and apparatus for targeted wake-up and frame extension for energy harvesting is disclosed. In one embodiment, a method performed by a station (STA) may compromise on receiving a zero energy (ZE) frame from an access point (AP) during an energy detection state indicating the presence of an energy harvesting (EH) window, harvesting energy during a determined duration during the EH window, and receiving a data portion of the ZE frame during an information decoding state based on the STA's current stored energy being above a first threshold and the signal strength of the received ZE frame being above a second threshold.

Description

Technical Field

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[0001] (Cross - Reference to Related Applications) This application claims the benefit of U.S. Provisional Patent Application No. 63 / 147,019, filed Feb. 8, 2021, the content of which is incorporated herein by reference.

Background Art

[0002] Both IEEE and 3GPP have the concept of a power - save - mode (PSM) for end - devices (e.g., STAs, WTRUs, etc.) that obtain services from an access point or gNB. The nominal procedures in the power - save - mode (PSM) include that the end - device negotiates a sleep cycle with the AP or gNB, wakes up according to a pre - negotiated periodicity (or event occurrence), indicates buffered data for reception or transmission when entering the "wake - up period", executes data transmission or data reception during the "wake - up period", and resumes PSM when there is a pause period in data transmission or reception. In this regard, a wake - up cycle can be a periodic and finite but long duration, and a portion within that cycle can be regarded as the "wake - up period" of the end - user device. When the device wakes up, the duration for which the device is "active" within the wake - up cycle depends on the amount of data queued for reception or transmission. Theoretically, once woken up, the end - user device can remain active throughout the duration of the wake - up cycle. During the "wake - up period", if there is no indication of queued data for reception / transmission, the end - user device resumes sleep at the end of the wake - up period.

[0003] One of the main reasons for PSM is energy saving. The longer a device can sleep, the longer the continuous standby time for the end-user device's power. A device that periodically wakes up is obligated to wake up even if there may be nothing to transmit downlink (i.e., to the end-user device). In other words, the act of waking up for the purpose of determining whether the device has data to receive, and simply activating the device's receiver, consumes a small amount of power. The identification information of the user device to which the data is to be transmitted is indicated by the AP or NB on the wake-up packet. According to current state technology, IEEE 802.11ba requires the end-user device to detect the wake-up packet, decode the protocol content, and determine whether the wake-up command is specifically addressed to it. The end-user device's identification information is encoded within the MAC payload. Therefore, the end-user device must first detect the presence of a valid PHY PDU, then decode the entire MAC packet (verify the FCS), and then confirm the presence of its identification information in the wake-up packet.

[0004] In 3GPP, DRX and eDRX are examples of methods that enable PSM mechanisms. In IEEE 802.11, the 802.11ba principle for wake-up receivers is an example of a method specified for PSM. As mentioned earlier, the main reason behind PSM is energy saving. The longer a device can sleep, the longer the end-user device's power standby time. However, the longer a device can sleep, the longer the resulting latency when enabling receive / transmit. [Overview of the project]

[0005] A method and apparatus for targeted wake-up and frame expansion for energy harvesting is disclosed. In one embodiment, a method performed by a station (STA) may compromise between receiving a zero-energy (ZE) frame from an access point (AP) indicating the presence of an energy harvesting (EH) window during an energy detection state, harvesting energy over a determined duration within the EH window, and receiving the data portion of a ZE frame during an information decoding state based on the STA's current stored energy exceeding a first threshold and the signal intensity of the received ZE frame exceeding a second threshold. The method may further compromise to initiate an uplink access attempt with the AP, provided that the STA detects a group ID.

[0006] The EH window may be indicated by the ZE preamble. The duration of the EH window may be indicated by the signature. The received ZE frame may be a frame intended for another STA. The harvested energy may be used to determine whether the STA has enough stored energy to receive the data portion of the ZE frame. The current stored energy may be stored in a capacitor. [Brief explanation of the drawing]

[0007] A more detailed understanding can be obtained from the following description, which is given as an example in conjunction with the attached drawings, where similar reference numbers in the drawings indicate similar elements. [Figure 1A] This is a system diagram showing an exemplary communication system in which one or more disclosed embodiments may be implemented. [Figure 1B] This is a system diagram showing an exemplary wireless transmit / receive unit (WTRU) that may be used in the communication system shown in Figure 1A, according to one embodiment. [Figure 1C]This is a system diagram showing an exemplary radio access network (RAN) and an exemplary core network (CN) that may be used in the communication system shown in Figure 1A according to one embodiment. [Figure 1D] This is a system diagram showing further exemplary RAN and further exemplary CN that may be used in the communication system shown in Figure 1A according to one embodiment. [Figure 2] These are exemplary 802.11ax single and multi-user frame formats. [Figure 3] This is an example of the 802.11ax PPDU format. [Figure 4] This is an example MAC frame containing a wake-up packet. [Figure 5] This is an example of an 802.11ba wake-up packet. [Figure 6] This is an example 802.11ba wake-up procedure using WuR. [Figure 7] This is an example of a wake-up preamble configuration. [Figure 8] This is a graph of the theoretical availability space for appropriate preambles. [Figure 9] This is an exemplary WuP signature and associated partition. [Figure 10] This is an example of a function-specific WuP signature. [Figure 11] These are various exemplary WuP types. [Figure 12] This is a diagram illustrating exemplary ZE-WuR transmission options from a ZE-WuR AP. [Figure 13] This is a diagram illustrating the ZE-WuR receiving options from a ZE-WuR AP. [Figure 14] This is a diagram illustrating a dedicated resource for multi-tone wake-up. [Figure 15] This is an example diagram of shared resources for multitone wake-up. [Figure 16] A diagram of an exemplary shared resource for single - tone wake - up. [Figure 17] A flowchart showing an exemplary process for resource determination of WuP transmission. [Figure 18] An exemplary seed and seed window for WuP transmission. [Figure 19] A diagram representing response latency and response offset determination. [Figure 20] A diagram of an exemplary preamble clip for facilitating ZE - WuR discovery. [Figure 21] A diagram of an exemplary discovery packet. [Figure 22] A diagram showing an operating region for energy harvesting. [Figure 23] A diagram showing WUR frames and field lengths. <000008​​​​​​​​​​​​​​​​​​​​​​​​Figure 1A shows an exemplary communication system 100 in which one or more disclosed embodiments may be implemented. The communication system 100 may be a multiple access system that provides content such as voice, data, video, message transmission, and broadcast to multiple wireless users. The communication system 100 may enable multiple wireless users to access such content through the sharing of system resources, including wireless bandwidth. For example, the communication system 100 may use one or more channel access methods such as code division multiple access (CDMA), time division multiple access (TDMA), frequency division multiple access (FDMA), orthogonal FDMA (OFDMA), single-carrier FDMA (SC-FDMA), zero-tail unique-word discrete Fourier transform spread OFDM (ZT-UW-DFT-S-OFDM), unique word OFDM (UW-OFDM), resource block filter OFDM, and filter bank multicarrier (FBMC).

[0009] As shown in Figure 1A, the communication system 100 may include radio 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, but it will be understood that the disclosed embodiments intend 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 radio environment. For example, WTRU102a, 102b, 102c, and 102d, all of which may be referred to as stations (STA), may be configured to transmit and / or receive radio signals and may include user equipment (UE), mobile stations, fixed or mobile subscriber units, subscriber-based units, pagers, mobile 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 wearables, 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 an industrial and / or automated processing chain context), consumer electronic devices, and devices operating on commercial and / or industrial wireless networks. Any of WTRU102a, 102b, 102c, and 102d may interchangeably be referred to as UE.

[0010] The communication system 100 may also include base stations 114a and / or base stations 114b. Each of the base stations 114a and 114b may be any type of device configured to wirelessly interface with at least one of the WTRUs 102a, 102b, 102c, and 102d to facilitate access to one or more communication networks such as CN 106, the Internet 110, and / or other networks 112. As an example, base stations 114a and 114b may be a base transceiver station (BTS), a next-generation NodeB such as a NodeB, eNode B (eNB), Home Node B, Home eNode B, gNode B (gNB), a New Radio (NR) NodeB, a site controller, an access point (AP), a wireless router, and the like. Although base stations 114a and 114b are shown as single elements, it will be understood that base stations 114a and 114b may include any number of interconnected base stations and / or network elements.

[0011] Base station 114a may be part of RAN 104, which may also include other base stations such as a base station controller (BSC), a radio network controller (RNC), relay nodes, and / or network elements (not shown). 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 licensed spectrum, unlicensed spectrum, or a combination of licensed and unlicensed spectrum. Cells may provide coverage of radio services to a particular geographic area which may be relatively fixed or change over time. Cells may be further divided into cell sectors. For example, a cell associated with base station 114a may be divided into three sectors. Thus, in one embodiment, base station 114a may include three transceivers, i.e., one transceiver per sector of the cell. In one embodiment, the base station 114a may use 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.

[0012] Base stations 114a and 114b may communicate with one or more WTRUs 102a, 102b, 102c, and 102d via an air interface 116, which may be any suitable radio communication link (e.g., radio frequency (RF), microwave, centimeter wave, micrometer wave, infrared (IR), ultraviolet (UV), visible light, etc.). The air interface 116 may be established using any suitable radio access technology (RAT).

[0013] More specifically, as described above, the communication system 100 may be a multiple access system and may use one or more channel access schemes, such as CDMA, TDMA, FDMA, OFDMA, SC-FDMA, etc. For example, base stations 114a of RAN 104 and WTRU 102a, 102b, 102c may implement radio technologies such as Universal Mobile Telecommunications System (UMTS) Terrestrial Radio Access (UTRA), which may establish an air interface 116 using wideband CDMA (WCDMA). WCDMA may include communication protocols such as High-Speed ​​Packet Access (HSPA) and / or evolved HSPA (HSPA+). HSPA may include High-Speed ​​Downlink Packet Access (HSDPA) and / or High-Speed ​​Uplink Packet Access (HSUPA).

[0014] In one embodiment, base stations 114a and WTRUs 102a, 102b, and 102c may implement radio technologies such as Evolved UMTS Terrestrial Radio Access (E-UTRA), which may establish an air interface 116 using Long Term Evolution (LTE) and / or LTE-Advanced (LTE-A) and / or LTE-Advanced Pro (LTE-A Pro).

[0015] In one embodiment, the base station 114a and WTRUs 102a, 102b, and 102c may implement radio technologies such as NR radio access, which may establish an air interface 116 using NR.

[0016] In one embodiment, base station 114a and WTRU 102a, 102b, 102c may implement multiple radio access technologies. For example, base station 114a and WTRU 102a, 102b, 102c may implement LTE radio access and NR radio access together, for example, using the dual connectivity (DC) principle. Thus, the air interface utilized by WTRU 102a, 102b, 102c may be characterized by multiple types of radio access technologies and / or transmissions transmitted to and from multiple types of base stations (e.g., eNB and gNB).

[0017] In other embodiments, base stations 114a and WTRUs 102a, 102b, and 102c may implement wireless technologies such as IEEE 802.11 (i.e., Wireless Fidelity, WiFi), IEEE 802.16 (i.e., Worldwide Interoperability for Microwave Access, WiMAX), CDMA2000, CDMA2000 1X, CDMA2000 EV-DO, Provisional Standard 2000 (IS-2000), Provisional Standard 95 (IS-95), Provisional Standard 856 (IS-856), Global System for Mobile communications (GSM), Enhanced Data rates for GSM Evolution (EDGE), and GSM EDGE (GERAN).

[0018] The base station 114b in Figure 1A may be, for example, a wireless router, Home Node B, Home eNode B, or access point, and any suitable RAT may be used to facilitate wireless connectivity in local areas such as offices, homes, vehicles, campuses, industrial facilities, aerial corridors (for use by drones), roads, etc. In one embodiment, the base station 114b and WTRU 102c, 102d may implement wireless technologies such as IEEE 802.11 to establish a wireless local area network (WLAN). In one embodiment, the base station 114b and WTRU 102c, 102d may implement wireless technologies such as IEEE 802.15 to establish a wireless personal area network (WPAN). In yet another embodiment, base stations 114b and WTRUs 102c, 102d may establish picocells or femtocells using cellular-based RATs (e.g., WCDMA, CDMA2000, GSM, LTE, LTE-A, LTE-A Pro, NR, etc.). As shown in Figure 1A, base station 114b may have a direct connection to the internet 110. Therefore, base station 114b may not need to access the internet 110 via CN 106.

[0019] RAN104 may communicate with CN106, which may be any type of network configured to provide voice, data, applications, and / or Voice over Internet Protocol (VoIP) services to one or more of WTRU102a, 102b, 102c, and 102d. The data may have various quality of service (QoS) requirements, such as different throughput requirements, latency requirements, error tolerance requirements, reliability requirements, data throughput requirements, and mobility requirements. CN106 may provide call control, billing services, mobile location-based services, prepaid calls, internet connectivity, video distribution, etc., and / or high-level security functions such as user authentication. Although not shown in Figure 1A, it will be understood that RAN104 and / or CN106 may communicate directly or indirectly with other RANs using the same RAT or different RAT as RAN104. For example, in addition to being connected to RAN104 which may utilize NR radio technology, CN106 may also communicate with another RAN (not shown) using GSM, UMTS, CDMA2000, WiMAX, E-UTRA, or WiFi radio technology.

[0020] CN106 may also function as a gateway to WTRU102a, 102b, 102c, and 102d for access to PSTN108, the Internet 110, and / or other networks 112. PSTN108 may include a public switched telephone network providing plain old telephone service (POTS). The Internet 110 may include a global system of interconnected computer networks and devices, which use common communication protocols such as the transmission control protocol (TCP), the user datagram protocol (UDP), and / or the Internet protocol (IP) of the TCP / IP Internet Protocol suite. Network 112 may include wired and / or wireless networks owned and / or operated by other service providers. For example, network 112 may include another CN connected to one or more RANs that may use the same RAT as RAN104 or a different RAT.

[0021] Some or all of the WTRUs 102a, 102b, 102c, and 102d in the communication system 100 may include multimode capability (for example, WTRUs 102a, 102b, 102c, and 102d may include multiple transceivers for communicating with different radio networks via different radio links). For example, WTRU 102c shown in Figure 1A may be configured to communicate with base station 114a, which may use cellular-based radio technology, and base station 114b, which may use IEEE 802 radio technology.

[0022] Figure 1B is a system diagram showing an exemplary WTRU102. As shown in Figure 1B, the WTRU102 may include, among other things, a processor 118, a transceiver 120, a transmit / receive element 122, a speaker / microphone 124, a keypad 126, a display / touchpad 128, non-removable memory 130, removable memory 132, a power supply 134, a global positioning system (GPS) chipset 136, and / or other peripherals 138. It will be understood that the WTRU102 may include any partial combination of the aforementioned elements while maintaining consistency with one embodiment.

[0023] The processor 118 may be a general-purpose processor, a dedicated 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. The processor 118 may perform signal coding, data processing, power control, input / output processing, and / or any other functionality that enables the WTRU 102 to operate in a wireless environment. The processor 118 may be coupled to a transceiver 120 which may be coupled to a transmit / receive element 122. Figure 1B shows the processor 118 and transceiver 120 as separate components, but it will be understood that the processor 118 and transceiver 120 may be integrated together in an electronic package or chip.

[0024] The transmit / receive element 122 may be configured to transmit signals to or receive signals from a base station (e.g., base station 114a) via the air interface 116. For example, in one embodiment, the transmit / receive element 122 may be an antenna configured to transmit and / or receive RF signals. In one embodiment, the transmit / receive element 122 may be an emitter / detector configured to transmit and / or receive, for example, IR, UV, or visible light signals. In yet another embodiment, the transmit / receive element 122 may be configured to transmit and / or receive both RF signals and optical signals. It will be understood that the transmit / receive element 122 may be configured to transmit and / or receive any combination of radio signals.

[0025] Although the transmit / receive element 122 is shown as a single element in Figure 1B, the WTRU 102 may include any number of transmit / receive elements 122. More specifically, the WTRU 102 may utilize MIMO technology. Thus, in one embodiment, the WTRU 102 may include two or more transmit / receive elements 122 (e.g., multiple antennas) for transmitting and receiving radio signals via the air interface 116.

[0026] The transceiver 120 may be configured to modulate the signal transmitted by the transmit / receive element 122 and demodulate the signal received by the transmit / receive element 122. As described above, the WTRU 102 may have multimode capability. Therefore, the transceiver 120 may include multiple transceivers to enable the WTRU 102 to communicate via multiple RATs, such as NR and IEEE 802.11.

[0027] The processor 118 of the WTRU102 may be coupled to a speaker / microphone 124, a keypad 126, and / or a display / touchpad 128 (e.g., a liquid crystal display (LCD) display unit or an organic light-emitting diode (OLED) display unit) and may receive user input from these. The processor 118 may also output user data to the speaker / microphone 124, the keypad 126, and / or the display / touchpad 128. In addition, the processor 118 may access information from any type of suitable memory, such as non-removable memory 130 and / or removable memory 132, and store data in such memory. The non-removable memory 130 may include random-access memory (RAM), read-only memory (ROM), a hard disk, or any other type of memory storage device. The removable memory 132 may include a subscriber identity module (SIM) card, a memory stick, a secure digital (SD) memory card, and the like. In other embodiments, the processor 118 may access information from memory not physically located on the WTRU 102, such as on a server or home computer (not shown), and store data in such memory.

[0028] The processor 118 may receive power from the power supply 134, but may also be configured to distribute and / or control power to other components in the WTRU 102. The power supply 134 may be any suitable device for supplying power to 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.), a solar cell, a fuel cell, etc.

[0029] 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 the information from the GPS chipset 136, the WTRU 102 may receive location information from base stations (e.g., base stations 114a, 114b) via the air interface 116 and / or determine its location based on the timing of signals received from two or more nearby base stations. It will be understood that the WTRU 102 may acquire location information by any preferred location determination method while maintaining consistency with one embodiment.

[0030] The processor 118 may be further coupled to other peripherals 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, peripherals 138 may include an accelerometer, an electronic compass, a satellite transceiver, a digital camera (for photos and / or videos), a universal serial bus (USB) port, a vibration device, a television transceiver, a hands-free headset, a Bluetooth® module, a frequency modulated (FM) radio unit, a digital music player, a media player, a video game player module, an internet browser, a virtual reality and / or augmented reality (VR / AR) device, an activity tracker, and the like. Peripherals 138 may include one or more sensors. The sensor may be one or more of the following: gyroscope, accelerometer, Hall effect sensor, magnetometer, orientation sensor, proximity sensor, temperature sensor, time sensor, geolocation sensor, altimeter, light sensor, touch sensor, barometer, gesture sensor, biometric sensor, humidity sensor, etc.

[0031] WTRU102 may include a full-duplex radio in which the transmission and reception of some or all of a signal (for example, associated with specific subframes of both UL (for example, for transmission) and DL (for example, for reception) may be simultaneous and / or together. The full-duplex radio may include an interference management unit for reducing and / or substantially eliminating self-interference either through hardware (e.g., chokes) or signal processing via a processor (e.g., via a separate processor (not shown) or processor 118). In one embodiment, WTRU102 may include a half-duplex radio for the transmission and reception of some or all of a signal (for example, associated with specific subframes of either UL (for example, for transmission) or DL ​​(for example, for reception)).

[0032] Figure 1C is a system diagram illustrating RAN104 and CN106 according to one embodiment. As described above, RAN104 can communicate with WTRU102a, 102b, and 102c via the air interface 116 using E-UTRA wireless technology. RAN104 can also communicate with CN106.

[0033] RAN104 may include eNode-B160a, 160b, and 160c, but it will be understood that RAN104 may include any number of eNode-B while maintaining consistency with one embodiment. Each of eNode-B160a, 160b, and 160c may include one or more transceivers for communicating with WTRU102a, 102b, and 102c via the air interface 116. In one embodiment, eNode-B160a, 160b, and 160c may implement MIMO technology. Thus, eNode-B160a may, for example, use multiple antennas to transmit radio signals to and / or receive radio signals from WTRU102a.

[0034] Each of the eNode-B160a, 160b, and 160c may be associated with a specific cell (not shown) and may be configured to handle wireless resource management decisions, handover decisions, user scheduling, etc., in UL and / or DL. As shown in Figure 1C, the eNode-B160a, 160b, and 160c may communicate with each other via the X2 interface.

[0035] The CN106 shown in Figure 1C may include a mobility management entity (MME) 162, a serving gateway (SGW) 164, and a packet data network (PDN) gateway (PGW) 166. Although these elements are shown as part of CN106, it should be understood that any of these elements may be owned and / or operated by an entity other than the CN operator.

[0036] The MME162 can be connected to each of the eNode-B162a, 162b, and 162c in RAN104 via the S1 interface and can function as a control node. For example, the MME162 may perform roles such as authenticating users of WTRU102a, 102b, and 102c, activating / deactivating bearers, and selecting gateways for specific services during the initial attachment of WTRU102a, 102b, and 102c. The MME162 may provide control plane functionality for switching between RAN104 and other RANs (not shown) employing other radio technologies such as GSM and / or WCDMA.

[0037] The SGW164 can be connected to each of the eNode-B160a, 160b, and 160c in RAN104 via the S1 interface. The SGW164 can generally route and forward user data packets to and from WTRU102a, 102b, and 102c. The SGW164 can also perform other functions, such as anchoring the user plane during eNode B handovers, triggering paging when DL data is available to WTRU102a, 102b, and 102c, and managing and remembering the context of WTRU102a, 102b, and 102c.

[0038] SGW164 may be connected to PGW166, which may provide WTRU102a, 102b, and 102c with access to a packet-switched network such as the Internet 110 to facilitate communication between WTRU102a, 102b, and 102c and IP-enabled devices.

[0039] CN106 can facilitate communication with other networks. For example, CN106 can provide WTRU102a, 102b, and 102c with access to a circuit-switched network such as PSTN108 to facilitate communication between WTRU102a, 102b, and 102c and conventional terrestrial line communication devices. For example, CN106 may include, or communicate with, an IP gateway (e.g., an IP multimedia subsystem (IMS) server) that functions as an interface between CN106 and PSTN108. In addition, CN106 may provide WTRU102a, 102b, and 102c with access to another network 112, which may include other wired and / or wireless networks owned and / or operated by other service providers.

[0040] Although the WTRU is shown as a wireless terminal in Figures 1A to 1D, in certain representative embodiments, such a terminal is intended to be able to use a wired communication interface (e.g., temporary or permanent) with a communication network.

[0041] In a typical embodiment, the other network 112 may be a WLAN.

[0042] A WLAN in Basic Service Set (BSS) mode may have an Access Point (AP) of the BSS and one or more stations (STAs) associated with the AP. The AP may have access to or interfaces with a Distribution System (DS) or another type of wired / wireless network that carries traffic within and / or outside the BSS. Traffic originating outside the BSS to an STA may reach and be delivered to the STA via the AP. Traffic originating from an STA to a destination outside the BSS may be sent to the AP and then delivered to its respective destination. Traffic between STAs within the BSS may be sent, for example, via the AP; the source STA may send traffic to the AP, and the AP may deliver the traffic to the destination STA. Traffic between STAs within the BSS may be considered and / or referred to as peer-to-peer traffic. Peer-to-peer traffic may be sent between the source STA and the destination STA (for example, directly between them) in a direct link setup (DLS). In certain representative embodiments, the DLS may use 802.11e DLS or 802.11z tunneled DLS (TDLS). A WLAN using Independent BSS (IBSS) mode may not have APs, and STAs within or using IBSS (e.g., all STAs) may communicate directly with each other. The IBSS mode of communication may be referred to herein as “ad hoc” communication mode.

[0043] When using the 802.11ac infrastructure operating mode or a similar operating mode, an AP may transmit beacons on a fixed channel, such as the primary channel. The primary channel may be of a fixed width (e.g., a 20 MHz bandwidth) or a dynamically set width. The primary channel may be the operating channel of the BSS and may be used by the STA to establish a connection with the AP. In certain typical embodiments, Carrier Sense Multiple Access with Collision Avoidance (CSMA / CA) may be implemented, for example, in an 802.11 system. In the case of CSMA / CA, the STA, including the AP (e.g., all STAs), may sense the primary channel. If the primary channel is sensed / detected and / or determined to be busy by a particular STA, that STA may be backed off. A single STA (e.g., only one station) may transmit at any given time on a given BSS.

[0044] High-throughput (HT) STAs may use a 40 MHz wide channel for communication, which may be formed, for example, through a combination of a primary 20 MHz channel and adjacent or non-adjacent 20 MHz channels.

[0045] Very High Throughput (VHT) STAs may support channels with widths of 20 MHz, 40 MHz, 80 MHz, and / or 160 MHz. The 40 MHz and / or 80 MHz channels mentioned above may be formed by combining multiple consecutive 20 MHz channels. A 160 MHz channel may be formed by combining eight consecutive 20 MHz channels, or by combining two non-contiguous 80 MHz channels, which may be referred to as an 80+80 configuration. In the 80+80 configuration, after channel coding, the data may pass through a segment parser that can split the data into two streams. Inverse Fast Fourier Transform (IFFT) and time-domain processing may be performed separately for each stream. The streams may be mapped to two 80 MHz channels, and the data may be transmitted by a transmitting STA. At the receiver of a receiving STA, the operation described above for the 80+80 configuration may be reversed, and the combined data may be transmitted to Medium Access Control (MAC).

[0046] Sub-1 GHz operating modes are supported by 802.11af and 802.11ah. 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 bandwidths of 5 MHz, 10 MHz, and 20 MHz in the TV White Space (TVWS) spectrum, while 802.11ah supports bandwidths of 1 MHz, 2 MHz, 4 MHz, 8 MHz, and 16 MHz using the non-TVWS spectrum. According to a typical embodiment, 802.11ah may support meter-type control / machine-type communications (MTC), such as MTC devices in a macro coverage area. MTC devices may have certain capabilities, including support for specific and / or limited bandwidths (e.g., support only for that). MTC devices may include batteries with battery life exceeding a threshold (e.g., to maintain very long battery life).

[0047] A WLAN system capable of supporting multiple channels and channel bandwidths such as 802.11n, 802.11ac, 802.11af, and 802.11ah includes a channel that can be designated as the primary channel. The primary channel may have a bandwidth equal to the maximum common operating bandwidth supported by all STAs in the BSS. The bandwidth of the primary channel may be set and / or limited by an STA from among all STAs operating in a BSS that support the minimum bandwidth operating mode. In the 802.11ah example, the primary channel may be 1 MHz wide for an STA (e.g., an MTC type device) that supports (e.g., only) the 1 MHz mode, even if other STAs in the AP and BSS support 2 MHz, 4 MHz, 8 MHz, 16 MHz, and / or other channel bandwidth operating modes. Carrier sensing and / or Network Allocation Vector (NAV) settings may depend on the state of the primary channel. For example, if the primary channel is busy, an STA (which only supports 1MHz operating mode) sending to the AP may consider the entire available frequency band to be busy, even if the majority of the available frequency band is idle.

[0048] In the United States, the available frequency band that can be used by 802.11ah is 902MHz to 928MHz. In South Korea, the available frequency band is 917.5MHz to 923.5MHz. In Japan, the available frequency band is 916.5MHz to 927.5MHz. The total bandwidth available for 802.11ah is 6MHz to 26MHz, depending on the country code.

[0049] Figure 1D is a system diagram illustrating RAN104 and CN106 according to one embodiment. As described above, RAN104 can communicate with WTRU102a, 102b, and 102c via the air interface 116 using NR radio technology. RAN104 can also communicate with CN106.

[0050] RAN104 may include gNB180a, 180b, and 180c, but it will be understood that RAN104 may include any number of gNBs while maintaining consistency with one embodiment. Each of gNB180a, 180b, and 180c may include one or more transceivers for communicating with WTRU102a, 102b, and 102c via the air interface 116. In one embodiment, gNB180a, 180b, and 180c may implement MIMO technology. For example, gNB180a and 180b may use beamforming to transmit and / or receive signals to gNB180a, 180b, and 180c. Thus, gNB180a may, for example, use multiple antennas to transmit and / or receive radio signals from WTRU102a. In one embodiment, gNB180a, 180b, and 180c may implement carrier aggregation technology. For example, gNB180a may transmit multiple component carriers to WTRU102a (not shown). A subset of these component carriers may be on the unauthorized spectrum, and the remaining component carriers may be on the authorized spectrum. In one embodiment, gNB180a, 180b, and 180c may implement coordinated multi-point (CoMP) technology. For example, WTRU102a may receive coordinated transmissions from gNB180a and gNB180b (and / or gNB180c).

[0051] WTRU102a, 102b, and 102c may communicate with gNB180a, 180b, and 180c using transmissions associated with an expandable numerology. For example, OFDM symbol intervals and / or OFDM subcarrier intervals may vary for different transmissions, different cells, and / or different portions of the radio transmission spectrum. WTRU102a, 102b, and 102c may communicate with gNB180a, 180b, and 180c using subframes or transmission time intervals (TTIs) of varying or expandable lengths (e.g., varying numbers of OFDM symbols and / or varying durations of absolute time).

[0052] gNB180a, 180b, and 180c can be configured to communicate with WTRU102a, 102b, and 102c in standalone and / or non-standalone configurations. In a standalone configuration, WTRU102a, 102b, and 102c can communicate with gNB180a, 180b, and 180c without accessing other RANs (e.g., eNode-B160a, 160b, and 160c). In a standalone configuration, WTRU102a, 102b, and 102c can utilize one or more of gNB180a, 180b, and 180c as mobility anchor points. In a standalone configuration, WTRU102a, 102b, and 102c can communicate with gNB180a, 180b, and 180c using signals in unlicensed bands. In a non-standalone configuration, WTRU102a, 102b, and 102c can communicate with and connect to gNB180a, 180b, and 180c, while also communicating with and connecting to other RANs such as eNode-B160a, 160b, and 160c. For example, WTRU102a, 102b, and 102c can implement DC principles for substantially simultaneous communication with one or more gNB180a, 180b, and 180c and one or more eNode-B160a, 160b, and 160c. In a non-standalone configuration, eNode-B160a, 160b, and 160c can function as mobility anchors for WTRU102a, 102b, and 102c, while gNB180a, 180b, and 180c can provide additional coverage and / or throughput to service WTRU102a, 102b, and 102c.

[0053] Each of the gNB180a, 180b, and 180c may be associated with a specific cell (not shown) and may be configured to handle radio resource management decisions, handover decisions, user scheduling in UL and / or DL, network slice support, interaction between DC, NR and E-UTRA, routing of user plane data to User Plane Functions (UPFs) 184a and 184b, routing of control plane information to Access and Mobility Management Functions (AMFs) 182a and 182b, and so on. As shown in Figure 1D, the gNB180a, 180b, and 180c may communicate with each other via the Xn interface.

[0054] The CN106 shown in Figure 1D may include at least one AMF182a, 182b, at least one UPF184a, 184b, at least one Session Management Function (SMF)183a, 183b, and possibly a Data Network (DN)185a, 185b. Although the aforementioned elements are shown as part of CN106, it will be understood that any of these elements may be owned and / or operated by an entity other than the CN operator.

[0055] AMF182a and 182b can be connected to one or more gNB180a, 180b, and 180c in RAN104 via the N2 interface and can function as control nodes. For example, AMF182a and 182b may play roles such as user authentication for WTRU102a, 102b, and 102c, support for network slicing (e.g., handling different protocol data unit (PDU) sessions with different requirements), selection of specific SMF183a and 183b, management of registration areas, termination of non-access stratum (NAS) signaling, and mobility management. Network slicing can be used by AMF182a and 182b to customize CN support for WTRU102a, 102b, and 102c based on the type of service utilizing WTRU102a, 102b, and 102c. For example, different network slices may be established for different use cases, such as services that rely on ultra-reliable low latency (URLLC) access, services that rely on enhanced massive mobile broadband (eMBB) access, and services for MTC access. AMF182a, 182b may provide control plane functionality for switching between RAN104 and other RANs (not shown) using other radio technologies such as LTE, LTE-A, LTE-A Pro, and / or non-3GPP access technologies such as WiFi.

[0056] SMF183a and 183b may be connected to AMF182a and 182b in CN106 via the N11 interface. SMF183a and 183b may also be connected to UPF184a and 184b in CN106 via the N4 interface. SMF183a and 183b may select and control UPF184a and 184b and configure the routing of traffic through UPF184a and 184b. SMF183a and 183b may 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 may be IP-based, non-IP-based, Ethernet-based, etc.

[0057] UPF184a and 184b may be connected via the N3 interface to one or more gNB180a, 180b, and 180c within RAN104, thereby providing WTRU102a, 102b, and 102c with access to a packet-switched network such as the Internet 110 to facilitate communication between WTRU102a, 102b, and 102c and IP-enabled devices. UPF184 and 184b may perform other functions such as packet routing and forwarding, enforcement of user plane policies, support for multi-homed PDU sessions, processing of user plane QoS, buffering of DL packets, and providing mobility anchoring.

[0058] CN106 can facilitate communication with other networks. For example, CN106 may include, or communicate with, an IP gateway (e.g., an IP multimedia subsystem (IMS) server) that functions as an interface between CN106 and PSTN108. In addition, CN106 may provide WTRU102a, 102b, 102c with access to other networks 112, which may include other wired and / or wireless networks owned and / or operated by other service providers. In one embodiment, WTRU102a, 102b, 102c may be connected to local DN185a, 185b via UPF184a, 184b through N3 interfaces to UPF184a, 184b and N6 interfaces between UPF184a, 184b and DN185a, 185b.

[0059] With regard to Figures 1A-1D and the corresponding descriptions in Figures 1A-1D, one or more of the functions described herein with respect to one or more of the WTRU102a-d, base stations 114a-b, eNode-B160a-c, MME162, SGW164, PGW166, gNB180a-c, AMF182a-b, UPF184a-b, SMF183a-b, DN185a-b, and / or any other devices described herein may be performed by one or more emulation devices (not shown). An emulation device may be one or more devices configured to emulate one or more of the functions described herein. For example, an emulation device may be used to test other devices and / or simulate network and / or WTRU functions.

[0060] Emulation devices may be designed to implement testing of one or more other devices in a laboratory and / or operator network environment. For example, one or more emulation devices may perform one or more or all functions while fully or partially implemented and / or deployed as part of a wired and / or wireless network to test other devices in a communications network. One or more emulation devices may perform one or more or all functions while temporarily implemented / deployed as part of a wired and / or wireless network. Emulation devices may be directly coupled to another device for the purpose of testing and / or performing testing using over-the-air radio communications.

[0061] One or more emulation devices may perform one or more functions, including all of the above, while not implemented / deployed as part of a wired and / or wireless communication network. For example, emulation devices may be used in test laboratory test scenarios, and / or in undeployed (e.g., test) wired and / or wireless communication networks, to implement testing of one or more components. One or more emulation devices may be test equipment. Direct RF coupling and / or wireless communication via RF circuitry (e.g., which may include one or more antennas) may be used by emulation devices to transmit and / or receive data.

[0062] In advanced wireless technologies such as cellular and WLAN, the RF front-end can be a mix of passive and active components. For example, passive components may include Rx antennas, Tx / Rx path switches, and filters. These components require little to no power to function, if any. Conversely, active components require power to function. For example, oscillators tuned to the carrier frequency, low-noise amplifiers, and A / D converters in the Rx path are active components.

[0063] Advances in RF component design over the past few years have enabled the use of novel types of RF circuits that can process received RF waveforms collected by a receiving device via the antenna front end, even without an active power supply. For example, such a device can harvest energy from the received RF waveform to perform the circuitry necessary to process the signal. These passive receivers use RF components such as cascaded capacitors, zero-bias Schottky diodes, or MEMS to implement the necessary functions of voltage multipliers or rectifiers, charge pumps, and signal detectors. It is worth considering that passive receivers can operate in the antenna far-field and support a reasonable link budget. Hereafter, the terms passive receiver and zero-energy receiver may be used interchangeably.

[0064] A passive receiver can perform basic signal detection, such as correlation to a known signature waveform, and / or enter an energy harvesting mode by accumulating energy from the RF waveform entering the receiver front end via the Rx antenna. Link budget characteristics of small-area or medium-area cellular base stations are supported. For example, a passive receiver may be used as a wake-up radio to trigger an internal device wake-up and signal interrupt following detection of wake-up signaling, and then prompt the main modem receiver with an active RF component to wake up.

[0065] The reduction in device power consumption can be substantial when passive receivers are used. A typical cellular 3G, 4G, or 5G modem transceiver can easily require up to several hundred milliwatts (mW) to demodulate and process received signals during active reception, such as in RRC_CONNECTED mode. Power consumption increases or decreases depending on the number of active RF front-end chains on the device, the channel bandwidth used for reception, and the data rate received. When the device is in RRC_IDLE mode and no data is being received or transmitted, cellular radio power saving protocols such as (e)DRX ensure that the receiver only needs to be powered on a few times per second at most. Typically, the device can then perform tasks such as measuring the received signal strength of the serving cell and / or adjacent cells for the purpose of cell (re)selection procedures and paging channel reception. Furthermore, the device supports coherent demodulation to perform AFC and channel estimation. Device power consumption when in RRC_IDLE is on the order of a few mW. In R15eMTC and NB-IoT, the sequence detection circuit for processing the in-band wake-up signal in RRC_IDLE mode can also be implemented in the form of a dedicated wake-up receiver. This allows for the power to be cut off from critical parts of the A / D converter and digital baseband processor. However, several active components within the RF front end, such as low-noise amplifiers and oscillators, are still used. Device power consumption in RRC_IDLE can be reduced to approximately 1mW.

[0066] Figure 2 shows an exemplary 802.11ax frame structure 200. Figure 2 shows both a single-user frame structure 210 and a multi-user frame structure 230. As shown, the structure can be similar to those of 802.11n and 802.11ac. The structure consists of a preamble, a header, and data fields.

[0067] The frame format begins with a preamble. The first part of the preamble consists of a legacy (non-HE) training field 212 (single user) or a legacy (non-HE) training field 232 (multi-user). The second part consists of the HE preamble field. The legacy portion of the preamble includes L-STF (legacy non-HT short training field), L-LTF (legacy long training field), and L-SIG (legacy signal field). This legacy portion can be decoded by legacy devices. The legacy portion may be included for backward compatibility and coexistence with legacy WiFi devices. The L-SIG field may be used as a repeating legacy (non-HT) signal field. The HE preamble can only be decoded by 802.11ax devices. The HE preamble may contain HE-STF and HE-LTF patterns. The HE header may contain HE SIG-A and HE SIG-B fields. HE SIG-A may contain information about packets to be followed on both the downlink and uplink, MCS rate, modulation, BSS color, BW, spatial stream, remaining time in the transmission opportunity, etc. HE SIG-B may contain only multi-user packets. The HE-Data field carries the PSDU(s). A maximum packet expansion mode with a duration of 8μs or 16μs is used at the end of the 802.11ax frame.

[0068] The single-user frame format structure may also include the RL-SIG field 214, the HE SIG-A field 216, the HE-STF field 220, the HE-Data field 222, and the packet extension field 224. The multi-user frame structure may also include the RL-SIG field 234, the HE SIG-A field 236, the HE SIG-B field 238, the HE-STF field 240, the HE-LTF field 242, the HE Data field 244, and the pack extension field 246.

[0069] Figure 3 shows an exemplary 802.11 PPDU format 300. 802.11ax is sometimes abbreviated as High Efficiency (HE) in the 802.11 standard. HE supports four transmission modes: single-user (SU), single-user extended range (extended range SU), trigger-based, and multi-user (MU).

[0070] The HE SU PPDU format 310 may be used when sending to a single user. The HE SU PPDU format 310 may include a legacy preamble 312, an HE preamble 314, and a data field 316.

[0071] The legacy preamble 312 may include an L-STF field 318, an L-LTF field 319, and an L-SIG field 320. The L-STF field 318 may be 8 μs. The L-LTF field 319 may be 8 μs. The L-SIG field 320 may be 4 μs.

[0072] The HE preamble 314 may include the RL-SIG field 321, the HE-SIG-A field 322, the HE-STF field 323, and the HE-LTF field 324 (or more). The R-SIG field 321 may be 4 μs. The HE-SIG-A field 322 may be 8 μs. The HE-STF field 323 may be 4 μs. The data field 316 may include the data field 325 and the PE field 326.

[0073] The HE Extended Range SU PPDU format 330 can be used when sending to a single user, but further away from an access point (AP), such as in outdoor scenarios. The HE Extended Range SU PPDU format 330 may include a legacy preamble 332, an HE preamble 334, and a data field 336.

[0074] The legacy preamble 332 may include an L-STF field 338, an L-LTF field 339, and an L-SIG field 340. The L-STF field 338 may be 8 μs. The L-LTF field 339 may be 8 μs. The L-SIG field 340 may be 4 μs.

[0075] The HE preamble 334 may include the RL-SIG field 341, the HE-SIG-A field 342, the HE-STF field 343, and the HE-LTF field 344 (or more). The R-SIG field 341 may be 4 μs. The HE-SIG-A field 342 may be 16 μs. The HE-STF field 343 may be 4 μs. The data field 316 may include the data field 345 and the PE field 346.

[0076] The HE trigger-based PPDU format 350 can be used for uplink OFDMA and / or MU-MIMO transmissions. The HE trigger-based PPDU format 350 carries a single transmission and can be sent as an immediate response to a trigger frame sent by the AP. The HE trigger-based PPDU format 350 may include a legacy preamble 352, an HE preamble 354, and a data field 356.

[0077] The legacy preamble 352 may include an L-STF field 358, an L-LTF field 359, and an L-SIG field 360. The L-STF field 358 may be 8 μs. The L-LTF field 359 may be 8 μs. The L-SIG field 360 may be 4 μs.

[0078] The HE preamble 354 may include the RL-SIG field 361, the HE-SIG-A field 362, the HE-STF field 363, and the HE-LTF field 364 (or more). The R-SIG field 361 may be 4 μs. The HE-SIG-A field 362 may be 8 μs. The HE-STF field 363 may be 8 μs. The data field 316 may include the data field 365 and the PE field 366.

[0079] The HE MU PPDU370 format may be used when sending to one or more users. The HE MU PPDU370 format may be similar to the SU format, except that the HE-SIG-B field may be present. The HE MU PPDU370 format may include a legacy preamble 372, an HE preamble 374, and a data field 376.

[0080] The legacy preamble 372 may include an L-STF field 378, an L-LTF field 379, and an L-SIG field 380. The L-STF field 378 may be 8 μs. The L-LTF field 379 may be 8 μs. The L-SIG field 380 may be 4 μs.

[0081] The HE preamble 374 may include the RL-SIG field 381, the HE-SIG-A field 382, ​​the HE-SIG-B field 383, the HE-STF field 384, and the HE-LTF field 385 (or more). The R-SIG field 381 may be 4 μs. The HE-SIG-A field 382 may be 8 μs. The HE-SIG-B field 383 may be 8 μs. The HE-STF field 384 may be 4 μs. The data field 316 may include the data field 386 and the PE field 387.

[0082] Figure 4 illustrates an exemplary MAC frame 400 containing a wake-up packet. MAC frame 400 may include a MAC header 402, a frame body 404, and an FCS 406. MAC header 410 may include a frame control field 410, an ID field 412, and a type-dependent field 414. Frame control field 410 may include a type field 420, a protected field 422, a frame body present field 424, and a length / miscellaneous field 426. Length / miscellaneous field 426 may include a group address BU field 430, a key ID field 432, and a reserved field 434. Type-dependent field 414 may include a sequence number field 440 and a counter field 442. MAC packets may be preceded by the 802.11 "Legacy" PHY-PDU format and an 802.11ba PHY preamble to facilitate synchronization, as shown in Figure 5.

[0083] Figure 5 shows an exemplary 802.11ba wake-up packet 500. The 802.11ba wake-up packet 500 may include a “legacy” portion 502 which may include a legacy STF field 510, a legacy LTF field 512, and a legacy SIG field 514. The 802.11ba wake-up packet 500 may also include BPSK marker #1 504 and BPSK marker #2 506. The narrowband portion 520 may include a WuR-Sync field 522 and a WuR-Data field 524.

[0084] The “legacy” portion of the packet 502 may allow all legacy devices to decode the presence of an 802.11-compliant PHY PDU and then ignore its contents for the entire duration indicated within the duration element of the legacy SIG field. This method enables the coexistence of 802.11ba receivers and legacy 802.11 waveforms. An 802.11 station (STA) incorporates a Wake-up Receiver (WuR) that looks for a specially encoded waveform (e.g., OOK) to determine the presence of a WuP. The WuR may be a dedicated low-power receiver or a component integrated with a Primary Component Radio (PCR). The WuR listens for WuPs and consumes significantly less energy than the PCR in receive mode. If a WuP is received and the WuR successfully detects it, the WuR wakes up the PCR.

[0085] Figure 6 illustrates an exemplary 802.11ba wake-up procedure 600 using WuR602. As shown in Figure 6, PCR ("receiver") 604 can negotiate with AP ("transmitter") 606 to enter the PSM. AP606 requires the transmission of a data packet on the downlink toward PCR604. AP606 may transmit WuP608 encoding the "identification information" of WuR602 associated with PCR604. This identification information may be shown to PCR604 by AP606 during the "wake-up mode" negotiation in the initial stages before entering the PSM. WuR602 can then decode WuP608 (potentially one of more WuPs is needed for wake-up) and, if the identification information is correlated, transmit a wake-up signal to PCR604. PCR604 can transition from the off state to the on state and send a Poll PDU to AP606 to query pending data. AP606 can then send buffered data to PCR604 using one or more exchanges. Upon completion of the procedure, PCR604 can return to the off state and WuR602 can return to the on state.

[0086] In the example above, AP606, which supports this WuP608 transmission, is sometimes referred to as a WuR AP according to the IEEE 802.11ba standard. As shown in Figure 6, WuR602 does not know that WuP608 is addressed to WuR602 itself until it decodes the MAC portion of WuP608. The power consumed by WuR602 to decode the PHY PDU and MAC PDU can be assumed to be less than the power that would be consumed if PCR604 were used. As the number of STAs associated with the WuR AP increases, the WuR-SYNC portion of the PHY PDU can be used for synchronization purposes and as a trigger for all STAs with WuR to recognize WuP608. However, the identification information of WuR602 may also be encoded within the MAC PDU, which causes all WuRs to decode the MAC PDU before deciding to discard it. As the number of WuRs increases, the power consumption requirements for decode unnecessary WuPs worsen. This increased decoding of WuP608 reduces continuous battery standby time, especially since the primary reason for WuR602 is to extend battery life. In summary, the current technology solution involves waking up multiple WuRs when it may be necessary to wake up only one WuR or one subset of WuRs, and the WuRs must decode MAC PDUs to verify their addresses.

[0087] Within the 3GPP framework, unlike existing current technology devices, wireless transmit / receive units (WTRUs) implementing passive transceivers can benefit from near-zero power consumption when not actively transmitting or receiving at high data rates for the purpose of data exchange with a network or heavy control signaling. ZE receivers have already been considered to perform the following functions when in the RRC_IDLE / INACTIVE state and while harvesting energy:

[0088] To enable the WTRU to further benefit from the near-zero power consumption associated with ZE transceivers, the WTRU can utilize the ZE transceiver with backscatter-based UL to execute either a random access procedure and / or a data transmission procedure. The WTRU can then use the query signal of the serving BS to perform monostatic backscattering of either a 4-step random access type MSG1 or a 2-step random access type MSGA. The WTRU can also, with the assistance of another WTRU or facilitator, perform bistatic backscattering of either two messages MSG1 or MSGA.

[0089] Given the dependence of ZE transceiver transmissions on query signals from either the serving cell (BS) and / or other WTRUs / facilitators, a procedure is needed to enable coordination between the network and WTRUs equipped with ZE receivers for energy- and resource-efficient random access and grant-free access operation. A frame structure is required that enables efficient signaling supporting RRC_IDLE / INACTIVE state functionality via the ZE air interface without incurring significant power consumption overhead to the ZE receivers.

[0090] 802.11 systems are ubiquitous, and in the most practical scenarios, 802.11 traffic exists between two peer entities regardless of the presence of other radio access technologies. For example, in airport and office environments, it is common to find communication services that utilize both terrestrial cellular systems and 802.11 networks. 802.11 is also more ubiquitous, at least currently, in that a significant portion of data traffic is typically carried over 802.11 rather than over terrestrial cellular systems. This may be due to the existing situation where traffic is not typically measured over 802.11 but is typically measured and billed over cellular systems. Therefore, it is useful to utilize 802.11 not only for information delivery but also as a source for power delivery in the form of optimized waveforms for energy harvesting electronic circuits.

[0091] Zero-energy (ZE) devices are ultra-low-power communication devices that can be either auxiliary devices attached to a main radio or standalone devices such as IoT devices. A supplementary device in one representation might be a wake-up receiver (WuR). ZE devices can be constructed to include very few or zero active components, thus minimizing energy drain for either uplink or downlink transmission. This virtually battery-free operation relies on the ZE device harvesting energy from an ambient or dedicated source (or a combination of both) to participate in information reception and energy harvesting. ZE devices can also modulate backscattered information to the intended receiver using backscattering techniques with similar ambient or dedicated sources.

[0092] A wake-up receiver (WuR) can be an auxiliary or standalone communication device. In 802.11ba, a WuR can be a supplement to the main transceiver component within the 802.11 framework. One of the primary purposes of a WuR may be to allow the main transceiver component to turn off most of its active circuitry and enter a power-saving mode. While the main transceiver is sleeping, the WuR monitors. The WuR may receive a "paging signal or wake-up signal" from the serving AP, and if reception is successful, it may wake up the main transceiver component.

[0093] In the proposed embodiment, the WuR can be a pre-programmed and / or predetermined decision, in place of the main transceiver, including participating in low-rate communication. The WuR can communicate using energy harvesting (EH) and backscattering capabilities. The EH and regeneration capabilities may relate to energy storage requirements. In the proposed embodiment, the WuR may be more complementary than supplementary, as it may perform specific standalone functions.

[0094] The primary communication receiver (PCR) may be the main transceiver component. In one implementation, the PCR may be an STA as defined in standard 802.11. The STA may have a finite but decaying energy storage (in the exemplary case of an STA implemented in a handset) or a finite but static energy storage (in the exemplary case of an STA implemented in a desktop PC). In the case of a handset, the PCR may benefit from the WuR, as the STA may shut off most of its active circuitry and rely on the WuR to be woken up in response to AP paging. PCRs can typically be involved in high-speed communications reaching data rates of several Mbps (or even Gbps).

[0095] A wake-up packet (WuP) can be a paging signal sent by an AP or infrastructure node intended to wake up one or more WuRs. In some representations, a WuP may be more than just a wake-up signal and may readily provide supporting features such as phase / frequency tracking, local oscillation drift correction, and warnings for specific procedures. A WuP can be a purely physical layer signal (i.e., consumed and terminated in what is typically a PHY procedure), a MAC layer signal (i.e., a signal embedded within a frame format), or a signal consumed by an application (e.g., a public safety message that triggers a specific alert framework to be instantiated).

[0096] Each signal type has its advantages, but for WuR, the signal type that places the least burden on energy storage is appropriate. If WuR receives WuP and determines that WuR is not the intended destination, a considerable amount of energy is wasted because WuR's energy storage is quite small. In the proposed solution, WuR may terminate earlier if it detects, based on hierarchical rules, that WuP is not addressed to WuR. Furthermore, WuP may be consumed (or discarded) in PHY processing.

[0097] In most scenarios, the signal has a single objective. For example, between two communicators, a flag can signal danger when set and normal when not set. However, variations in the design can modify these variations. For example, a third state may be added, which may be a flag set but tilted 45 degrees to the right to signal the direction of the danger source when additionally signaling danger.

[0098] In the proposed embodiment, various WuPs can be mapped to specific functions (or procedures) and agreed upon by two peer communication entities. The same WuP or nested WuP intended for one function in WuR#1 may be used and / or assigned to other WuRs. The peer node responsible for performing the wake-up can hierarchically determine which WuPs can wake up one single WuR, one group, or more groups of WuRs. WuPs are sometimes synonymously referred to as "signatures or preambles." WuPs may be sequences such as M sequences or any suitable code sequences that can orthogonalize WuRs while ensuring high decryptability performance at the PHY layer.

[0099] The preamble clip may be part of the WuP. The preamble clip may also be a fractional part of the WuP and may be formulated as follows: If the preamble is a sequence of length N, the preamble clip may be a fractional part occupying K consecutive bits of the sequence of length N, where K ≤ N. N may typically be fixed for a particular radio access technology, while K may be deployment-specific. The (NK) bits of the WuP are used for different procedures. The preamble clip has special importance because if K bits are deemed invalid for that purpose, the WuR correlating the N-bit WuP may terminate prematurely. Thus, the preamble clip can be visualized as identification information of the transmitting entity and / or an implicit indicator of the transmitting entity's transmission and / or the receiving entity's joining of the network.

[0100] In wireless communication systems, synchronization between the transmitter and receiver is typically required. In 3GPP-based terrestrial cellular systems, synchronization can be achieved when the WTRU successfully receives the primary and secondary synchronization signals (PSS / SSS) and controls its local oscillator. The WTRU can always be downlink synchronized with the base station in such technology. In 802.11, synchronization can be achieved when the station reads the 802.11 header, which includes the synchronization field and training field.

[0101] 802.11ba may incorporate a scanning mechanism called discovery to enable the STA to detect mobility. WUR discovery frames are used to enable the STA to perform low-power network discovery without interrupting connectivity with the current AP, and discovery through a selected channel scan. The STA may associate with the strongest signal. An 802.11ba-compliant AP configures the STA with a "fast initial link setup" discovery frame that allows the STA to switch channels and scan for APs on the indicated channel. If a stronger AP is perceived on the channel indicated in the discovery frame, the STA may reassociate.

[0102] The proposed embodiment eliminates the need for a separate channel and the need for the STA to reassociate when not necessary. For example, if the STA is an Internet of Things (IoT) sensor device (e.g., a sea level monitoring sensor near an oil rig) that sends packets once every 24 hours, and the sensor's next transmission opportunity could still be 21 hours away, then if the device itself discovers it has drifted from its previous AP location to that AP, there is no need to reassociate it to a different AP. Unless necessary, the same IoT sensor may drift further to another AP within the same BSS, or probabilistically drift back to the same initial AP to which it was associated, so there is no need to reassociate it. This solution allows the device to determine that it has moved from one AP to another, determine if the new AP is part of a logical grouping known to be the same BSS (or) acceptable, receive a wake-up signal from one or more APs sharing the groping (e.g., BSS), and reassociate to the new AP only if necessary.

[0103] With current technology, WuP can be of a single type and single purpose. More importantly, current technology allows WuR to determine the wake-up signal after decoding the MAC frame of the signal. The effect of WuP can be converted to either (1) wake-up PCR or (2) no action.

[0104] In the proposed embodiment, the peer transmitting entity may allow the ZE WuR to take one or more actions, namely (1) delay wake-up until an event or opportunity conveniently exists, (2) fully wake up to participate in duplex, bidirectional communication, and / or (3) partially wake up to consume a downlink-only payload without feedback.

[0105] A headerless control element can be an argument to a WuP, which has a fixed size and can nominally be consumed within the physical layer. The physical layer consumes the WuP (e.g., by correlating the WuP signature) and decodes a fixed-size payload with several bits of augmentation in hardware without requiring an additional microprocessor.

[0106] The preamble tracking set can be a set of 1 to M WuPs associated with a WuR. A WuR can typically be assigned an explicit procedure for tracking and decrypting a set of M WuPs, or it implicitly derives up to M WuPs applicable to being serviced within an AP(or) BSS. The set M may depend on the expected service deployment and type in the infrastructure. The tracking set provides a comprehensive addressing of WuRs (or one or more WuRs in the case of group wake-up) within the BSS. Conversely, a WuP not in the tracking set may indicate that the WuR is under a non-serving AP(or) BSS.

[0107] Piano nodes that depend on the relative priorities of some WuRs among ZE WuRs may assign hierarchically encoded WuPs. A WuP of length N bits may be encoded in a hierarchy in such a way that the highest-priority WuR can terminate decoding as soon as it detects a first few-bit mismatch, while a lower-priority WuR must fully correlate before determining the need to terminate decoding. For example, in a group of ZE-WuR(1, 3, 5), assume that ZE-WuR 1 has a higher priority than both ZE-WuR3 and 5, and ZE-WuR3 has a higher priority than 5. The WuP signature encodes a hierarchy that allows ZE-WuR1 to skip decoding much earlier than ZE-WuR3 and 5 when the WuP is not addressed to it. In an N-bit WuP signature, assume that the last J bits are used to indicate the hierarchy. The (N-J) bits are decoded by all of ZE-WuR1, 3, 5. However, in ZE-WuR1, it is necessary to decode j≤J bits to detect that the WuP is not addressed to itself, while in ZE-WuR3, it is necessary to decode (j + d)≤J bits to detect that the WuP is not addressed to itself, and finally in ZE-WuR5, it is necessary to decode up to a maximum of (J + d + e)<J bits to determine that the WuP is not addressed to itself.

[0108] A STA configured using a discovery channel detects the presence of other APs by tuning to channels signaled within the discovery channel. When associating with a new AP discovered through this process, the selection can be based on the received signal strength (the strongest, first selected) without having a realistic consideration of whether the AP selected for association has sufficient capacity. Optimizations have been proposed in the prior art to signal in a quantized representation such as relative capacity, probability of successful association, etc. The STA can receive these inputs and determine which AP the STA desires to associate with, which is not necessarily the strongest one measured by the STA.

[0109] A proposal for a new frame format within the 802.11 framework (e.g., as an extension to 802.11ba or a new interface) that enables coexistence between ZE WuR and legacy, current technology devices in a new infrastructure supporting upgrades to the 802.11 standard. The frame format allows for accurate interpretation by both legacy and ZE WuR for information transmission and energy transfer. Energy transfer may be opportunistic, ZE WuR-only, or simultaneous.

[0110] Simultaneous power and information transmission can be a process in which both information and energy are delivered to the intended recipient. A frame carrying information to one STA may incidentally piggyback a power-optimized energy waveform for the WuR STA. Signatures are selected so that harvest targets can be met progressively and within a limited duration. Conversely, an in-band full-duplex infrastructure node can transmit information to a normal node, and a ZE WuR device can opportunistically backscatter over time-frequency resources as if it were a query signal.

[0111] The temporary storage device may not be specific in that it may include a particular low-capacity, fast-charging, temporary miniature battery or other form of energy storage device. In high-level design of a receiver for optimal operation, two key variables during receiving operation are considered: namely, the incident signal strength (power level) and the current energy storage level. Device operation can be characterized with respect to fundamental conceptual thresholds that govern its receiver operation. Depending on the stage of receiving processing while receiving a ZE frame, and based on the PHY frame structure, an active ZE WuR receiver can be in one of two basic states: signature detection, i.e., searching / listening for ZE WuP, or data frame decoding / receiving. In this estimation, the areas that need to be understood are the minimum energy required for operation and / or detection, the signal power threshold for initiating harvesting, and the threshold for declaring sufficiency.

[0112] Below, we will describe at least two proposed solutions. One proposes an extension to the 802.11 frame format, and the other proposes that the STA employ a zero-energy wake-up receiver (ZE-WuR) component to minimize energy consumption in order to perform the wake-up function.

[0113] In one proposed solution for ZE-WuR, ZE-WuR does not need to decrypt the entire WuP and may terminate early. The first part of the WuP provides ZE-WuR with enough information to determine if the WuP is addressed to itself and to use the same WuP further to perform a synchronization procedure. MAC PDU information within the WuP is decrypted only if necessary.

[0114] The WuP may be configured such that the WuP MAC payload follows immediately after the WuP preamble. The WuP may be transmitted by a ZE-WuR AP intended to wake up the PCR of one or more STAs. The PCR of the STAs may be woken up by the associated ZE-WuR. In this proposed solution, the wake-up may be performed using a physical layer preamble. The preamble may be an M sequence of length N bits. The length of the preamble N may be variable and may be dynamically determined by the ZE-WuR AP.

[0115] The preamble may be used alone by the receiving ZE-WuR for at least one of three main reasons: (1) synchronization, (2) determining whether the ZE-WuR AP has addressed the wake-up command, and (3) the purpose of the wake-up. This proposal involves assigning a unique (or) carefully managed preamble sequence to the ZE-WuR. During the association time, the STA's PCR exchanges "wake-up" mode setup parameters and receives one or more WuP preamble identification information.

[0116] Figure 7 illustrates an exemplary wake-up preamble configuration 700. As shown in Figure 7, the PCR in STA702 performs a wake-up mode exchange with the ZE-WuR AP704, indicating the number of preambles and the internal priority processing of different WuPs. It may be shown that STA702 can accept up to N different ZE-WuR preamble sequences. The ZE-WuR AP704 configures up to M (M ≤ N) preambles, and the preamble information to STA702 indicates preamble information that shows a local mapping between “preamble functions” and “assigned priorities”. For example, “preamble function #1” may be “Wake up, power on humidity sensor”, and “preamble function #2” may be “Wake up, transmit standby power status”. In one embodiment, the preamble “functions” are performed by the ZE-WuR AP704 itself, and in the relevant embodiment, the ZE-WuR 706 wakes up the PCR to perform the preamble “functions”. The preamble is function-specific and must be performed after either ZE-WuR706 or PCR wakes up.

[0117] In one embodiment, the ZE-WuR AP704 may determine the number of preambles that can be assigned to the STA and may respond to the STA with up to M (M ≤ N) "function-specific" preamble sequence indices. The priority assigned to each preamble may be indicated to the ZE-WuR STA by the ZE-WuR AP704. The PCR of the STA constitutes the preamble and priority in the ZE-WuR AP704. Upon entering zero-energy mode, the ZE-WuR AP704 listens to the preamble and determines whether the preamble is addressed to the ZE-WuR AP704 and whether the PCR needs to be woken up or whether the ZE-WuR AP704 can perform the task itself.

[0118] In 802.11ba, several M sequences were analyzed for their synchronization performance, and M sequences that met the "balanced" and "executable" criteria were considered to exhibit nearly identical performance when adopted as WuR SYNC packets for low date rates and high data rates. The selected M sequences to be standardized are given in equation (30-9) of 802.11ba / D6.0. The usefulness of M sequences as preambles for WuR SYNC has been thoroughly studied in 802.11ba and is supported in 17 / 0997r0 and 17 / 1343r0. However, WuR SYNC can only be used for synchronization and triggering purposes and cannot be used to uniquely wake up WuR.

[0119] Assuming a length of K bits, the number of different bit sequences that can be formed is equal to 2K. If constraints are imposed on which subset of 2K can be selected, the available choices will be limited. For example, if the available sequences must satisfy a "balance criterion," the number of available sequences may be reduced to approximately 2K-1. In addition, if there is a further constraint of a "run criterion," the number of available sequences will be further reduced. The "balance criterion" requires that the selected sequence has an even number of zeros and ones in it. The "run criterion" requires that the selected sequence cannot contain more consecutive ones or zeros than the run count value "C". For example, if the run criterion requires that the number of consecutive ones or zeros is less than 5, then all sequences with more than 5 consecutive ones or zeros are unusable.

[0120] Figure 8 illustrates the theoretical availability space for a suitable preamble. As shown in Figure 8, the number of available sequences increases as the length of the M sequence increases. The number of available sequences as a percentage of available sequences at each length decreases. However, the amount of available preambles can be very large. Using an arbitrary example, if the length of the M sequence is 24, there are approximately 1.8 million available sequences.

[0121] According to the current 802.11 standard, the theoretical maximum number of associations in a ZE-WuR AP can be approximately 2000. Knowing the maximum number of associations that can be supported allows for the determination of an assignable average preamble for each associated STA. However, it should be noted that some preambles may be mapped to groups of STAs, and that a ZE-WuR AP may decide to wake several PCRs simultaneously. There can be several determinants regarding how STAs are grouped into a particular preamble. For example, a group of STAs may be mapped to a particular wake-up preamble given (1) their proximity to each other, i.e., geographical proximity, (2) the function of the STA (e.g., a particular type of sensor), and / or (3) the distance from the WuR AP (e.g., via long-range path loss estimation to / from the STA).

[0122] In 802.11ba, the M sequence does not encode any identification information of any WuR STA. This is purely intended as a mechanism for WuR to maintain synchronization. There is also a cyclic shift applied to the 13 subcarriers through which the WuR SYNC is transmitted. A single M sequence of length 32 can be used as the WuR-SYNC in 802.11ba for LDR. The bitwise complement of the same sequence is used for HDR. WuR receives the WuR SYNC and correlates it by comparing it to the expected sequence. If the received sequence is correlated, WuR wakes up PCR to perform MAC-PDU decoding. In one embodiment, the WuP preamble can be an N-bit preamble that can be split into "A+B" bits. The "A" bit of the ZE-WuR preamble may also be called the "preamble clip" and indicates the identification information of the ZE-WuR AP. The "B" bit of the WuP preamble may be "ZE-WuR identification information" that identifies an individual or a group of ZE-WuRs.

[0123] Figure 9 illustrates an exemplary configuration of the WuP described above. As shown in Figure 9, the length of the preamble clip 902 may be long enough for the WuR to perform synchronization. In one embodiment, the length of the preamble clip may be dynamically selected by the ZE-WuR AP, the length may be explicitly indicated to the STA, or the STA may programmatically derive the length. Since the identification information of the ZE-WuR AP may be implicit in the preamble clip, any ZE-WuR associated with a ZE-WuR AP can perform synchronization using a preamble clip from any WuP preamble, even if the WuP does not target itself. The identification information portion of the WuP preamble allows the ZE-WuR to determine whether the WuP is addressed to it. The set of preambles that the ZE-WuR AP can use is determined by the preamble clip. The preamble clip may be keyed to the first K bits of the WuP preamble. For example, bits [1:K] are from the generator sequence keyed to the ZE-WuR AP's BSSID (or any other ID). The first K bits may also be implicit identifiers without a specific derivation of the AP's identifier or a mapping to the AP's identifier. Bits [K+1:N] are the ZE-WuR-identifier 904 bits. The total of N bits constitutes the ZE-WuR's wake-up signature. The K bits of any ZE-WuR signature may be used by any ZE-WuR associated with the ZE-WuR AP (i.e., the domain of the ZE-WuR AP) for synchronization purposes.

[0124] In one embodiment, the preamble clip 904 can encode AP identification information. In such a case, the generator sequence may be known in advance between the ZE-WuR STA and the ZE-WuR AP. Thus, the set of sequences applicable to the BSS may also be known in advance. The ZE-WuR AP may exchange one or more generator seeds with the STA during the ZE-WuR mode setup procedure. Based on the generator seeds, the STA can derive the preamble clip(s) applicable within the ZE-WuR AP and BSS. In one embodiment, the preamble clip in the WuP signature may assist the ZE-WuR in detecting that it has left the catchment area of ​​the ZE-WuR AP it is currently associated with and entered the catchment area of ​​another WuR AP in the BSS or ESS. The set of WuP signatures that the ZE-WuR can correlate may be called the signature monitor set.

[0125] A ZE-WuR STA moving from a geographic area served by one ZE-WuR AP within a BSS / ESS to another ZE-WuR AP can detect potential changes in the server. Since preamble clips can be used by ZE-WuR to discover serving ZE-WuR APs, a discovery mechanism that typically requires ZE-WuR to monitor discovery channels is unnecessary. In one embodiment, ZE-WuR may consist of one or more WuP signatures, each consisting of a WuP preamble clip and a WuR signature. ZE-WuR correlates to a pre-configured list of WuP preamble clips to detect whether they are under its serving ZE-WuR AP or have moved to the catchment area of ​​another ZE-WuR AP within the ESS / BSS.

[0126] In a relevant embodiment, the ZE-WuR can correlate a WuP preamble clip and use it for synchronization. The WuP preamble clip can be used by any ZE-WuR associated with a serving WuR AP, since the preamble clip is configured in the ZE-WuR. The preamble clip may be indicated by the ZE-WuR AP during association setup, or the preamble clip may be derived by the ZE-WuR based on the generator seed and the identification information of the ZE-WuR AP. In one embodiment, the selection of the WuP signature used by the ZE-WuR AP also implicitly indicates to the ZE-WuR whether it can optionally choose not to wake up the PCR. In a relevant embodiment, the selection of the WuP signature used by the ZE-WuR AP may also indicate to the ZE-WuR whether a delayed wake-up is preferred. If ZE-WuR correlates and detects such a preamble, an implicit timing can be inferred by ZE-WuR as a delay that ZE-WuR must undergo before waking up the PCR.

[0127] In other embodiments, a preamble clip or an entire WuP signature may be mapped one-to-one to a function. A ZE-WuR AP may configure several WuP signatures in the ZE-WuR, indicating that each WuP maps to one or more functions that the ZE-WuR associated with the PCR can perform. When the ZE-WuR decodes a WuP signature, the corresponding function to be performed may be implicitly (or explicitly) derived. The selection of a WuP signature triggers the ZE-WuR to perform the corresponding function. In relevant embodiments, a WuP signature informs the ZE-WuR that a wake-up may be required, but that no reception or transmission is necessary. An example of such a function includes the ZE-WuR receiving a WuP signature, waking up the PCR to perform a temperature read, storing it in local memory, and returning to sleep. Alternatively, instead of waking up the PCR, the ZE-WuR itself may perform such a function. In either scenario, media access may not be required for either transmitting or receiving information over the 802.11 channel. Figure 10 illustrates an exemplary function-specific WuP signature.

[0128] In one embodiment, the ZE-WuR can correlate the entire WuP and match the indicated ZE-WuR identification information with a pre-configured WuP signature. The ZE-WuR correlates and matches the WuP signature with one or more configured identification pieces. The signature may be individually addressed (wake-up for only one ZE-WuR), or alternatively, the signature may be group-addressed (wake-up for two or more ZE-WuRs). If the ZE-WuR cannot match the pre-configured signature with the WuP signature, the ZE-WuR may refrain from decoding the MAC-PDU that may follow the WuP signature.

[0129] In one embodiment, a bank of K collimators may be used in the WuR to correlate an received WuP signature with K pre-configured signatures. In an alternative embodiment, the WuR may be designed to implement reconfigurable collimators. The collimators in the WuR may be implemented as programmable low-power devices and may be modified as needed. In one embodiment, a WuP signature can encode a hierarchical address. In a hierarchical scenario, the hierarchical identification information has a cascaded level of wake-up signatures. The ZE-WuR correlates the received signature with the stored signatures by hierarchically decoding it. If the hierarchy is broken, the ZE-WuR considers the signature invalid and terminates decoding. Support for and presence of hierarchical WuP signatures may be indicated by the ZE-WuR AP during the time of association.

[0130] In one embodiment, the size of the WuP preamble may be static and set to N bits. This size N may be common across all ZE-WuR APs, regardless of geography, in such embodiments. In alternative embodiments, the size of the WuP signature may be dynamic and may vary from N bits to M bits. The WuP signature size used by the ZE-WuR AP may be signaled to the STA during association setup. If the size can be changed dynamically without explicit signaling, the ZE-WuR AP indicates that dynamic WuP signature sizes are enabled in the system. In one embodiment, the selection of a WuP preamble clip may implicitly map to a dynamic length. In such embodiments, ZE-WuR correlates with the WuP preamble clip and, depending on the preamble clip, identifies the length of the WuP signature. In further embodiments, the preamble clip may encode a hierarchy length indication. The K-bit preamble clip not only provides synchronization, but also allows ZE-WuR to hierarchically determine the length of the WuP signature that it must correlate.

[0131] Furthermore, ZE-WuR can utilize both the preamble clip and the ZE-WuR identification portion for synchronization, assuming prior knowledge of a tracked set of preamble clips and IDs. The tracked set of preamble clips can also be considered a monitored preamble set for WuR.

[0132] In summary, one proposed solution can be summarized as follows: receive the WuP, which is split into a preamble clip and a WuR identifier signature; correlate the preamble clip portion to determine the sending entity; correlate the WuR identifier portion to perform a function-specific task.

[0133] A WuP signature can consist of a twin-partitioned preamble clip and WuR identification information. The preamble clip can identify the transmitting AP as a serving AP and / or another AP within the BSS / ESS. AP identification information can be encoded within the preamble clip. The ZE-WuR termination can be decoded early if the AP identification portion of the WuP is mismatched. A preamble clip encoding a dynamic length of K bits. A ZE-WuR that self-determines a complete set of preamble clips applicable in the BSS / ESS based on a seed generator sequence. A ZE-WuR that detects mobility events based on preamble clips of other APs within {BSS,ESS} without requiring reassociation. A ZE-WuR that requests one or more function-specific WuP signatures. A ZE-WuR that indicates autonomously determined function priorities and support for programmable / reconfigurable preamble correlators. An AP that assigns one of more function-specific signatures. A ZE-WuR that receives a function-specific WuP and executes the corresponding function without needing to wake up PCR.

[0134] WuP signatures can be broadly classified into five types. WuP Type 1 may function as a SYNC for all ZE-WuRs associated with a particular ZE-WuR AP. ZE-WuRs associated with a ZE-WuR AP use a WuP preamble clip for synchronization from any WuP addressed to any ZE-WuR. Type 1 may be used by ZE-WuRs for synchronization and clock correction purposes, and the rest of the WuP may not be necessary for decoding. This may be a WuP signature-based wake-up, and it may not be necessary to decode the MAC PDU. Note that any ZE-WuR type in a packet can function as a ZE-WuR Type 1 for any ZE-WuR.

[0135] WuP Type 2 can be a “short wake-up” instruction addressed to either an individual or a group of ZE-WuRs. In “short wake-up” mode, a ZE-WuR wakes up a PCR solely for the explicit purpose of “receiving” a short packet (or a finite, known number of packets) from a ZE-WuR AP. The TXOP may be known in advance, and the PCR waits only to receive, resuming sleep as soon as its routine is complete. This may be a WuP signature-based wake-up and may not require decoding of the MAC PDU.

[0136] WuP Type 3 can be a “full wake-up” instruction addressed to either an individual or a group of ZE-WuRs. In “full wake-up” mode, a ZE-WuR can fully wake up a PCR. A PCR may be required in such a full wake-up to poll the ZE-WuR AP and send / receive conversation data. A full wake-up may also be for the explicit purpose of “sending and / or receiving” some data packets to / from a ZE-WuR AP. A TXOP may not be known, and the PCR can wait for as long as necessary to complete the routine, after which it can resume sleep. This may be a WuP signature-based wake-up and may not require decoding of the MAC PDU.

[0137] WuP type 4 may be in “soft wake-up” mode. ZE-WuR can optionally wake up PCR. When a type 4 WuP is received, ZE-WuR AP may indicate that a “lower priority” procedure is pending for STA at ZE-WuR AP, and that PCR may be woken up on a best-effort basis. Soft wake-up also implicitly defines the maximum time at which ZE-WuR may choose not to wake up PCR. Examples of such procedures may include non-urgent ZE-WuR mode renegotiation requests. Upon receiving a type 4 WuP, etc., ZE-WuR sets the “delayed wake-up” flag. PCR works up when an opportunistic reason arises to wake up PCR, or when the maximum time for delayed wake-up has expired at ZE-WuR. This may be a WuP signature-based wake-up and may not require decoding of the MAC PDU.

[0138] WuP type 5 may be in "no wake-up required" mode. In "no wake-up required" mode, the ZE-WuR may receive a MAC-PDU targeting the PCR, but no further transactions are required. When a type 5 WuP is received, the ZE-WuR can decode the MAC-PDU itself, store it in a local repository, and later set a flag to remind the PCR to correspond to the stored information. Examples of such wake-ups would be configuration uploads / configuration modifications for the PCR, which could be updates to humidity sensor or calibration data.

[0139] Except for WuP type 5, ZE-WuR does not need to decode the MAC PDU. Wake-up determination may simply be based on the correlation of the WuP signature.

[0140] Figure 11 illustrates the five WuP types described above. Types 1-4 are shown in format 1110 of Figure 11. Type 5 is shown in formats 1130 and 1150.

[0141] Format 1110 may include an N-bit WuP signature 1112 and a headerless control element 1114. The N-bit WuP signature may include a preamble clip field 1116 and a WuR ID field 1118. The headerless control element 1114 may include a WuP OPT field 1120, a delayed wake-up indicator field 1122, a linger field 1124, and a CRC field 1126. In format 1110, there is no MAC header, and only the headerless control element 1114 exists following the WuP signature 1112. The headerless control element 1114 may be protected by the CRC field 1126. MAC processing refers to processing that can conventionally be performed in the MAC layer, including CRC calculation. In the above WuR type, the headerless control element 1122 may be considered an extension of the PPDU.

[0142] The ZE WuR decodes at least the WuR-OPT field 1120 of the WuP packet and continues to decode the following few bits if the WuP type is 1-4. In this case, the PPDU may be as shown in the first part of Figure 11. For WuP type 5, the WuR decodes the packet by referring to a much larger packet embedded within the MAC frame, which is potentially done by a microprocessor. The WuP OPT 1120 may be a field indicating the ZE-WuR type. The delayed wake-up indicator field 1122 is present for ZE WuR type 4. For soft wake-up, the delayed wake-up indicator field 1122 indicates the maximum time applicable to delay the wake-up. The delayed wake-up indicator field 1122 may be a timer or a quantized value representing a time offset from the current UTC. A ZE-WuR that receives a ZE-WuR OPT indicating a type 4 wake-up wakes up the PCR at an opportune time. In the worst-case scenario, ZE-WuR wakes up PCR when the wake-up delay time expires.

[0143] Linguafield 1124 is present for ZE-WuR type 2 when the ZE-WuR AP indicates that it should continue short wakeups for a while due to uncertainty in channel access caused by DCF. The ZE-WuR AP can transmit short packets with nothing additional to transmit. In other cases, access to the media may be delayed due to increased demand for the media from several competing transmitters. The ZE-WuR AP can instruct the ZE-WuR to notify PCR to stay during short wakeups due to uncertainty in channel access. In all types described above, the information may be transmitted by the ZE-WuR AP as a PHY PDU without a MAC PDU component. To protect the authenticity of the PHY PDU, a CRC may be attached to the headerless control element following the ZE-WuR signature component.

[0144] Formats 1130 and 1150 indicate type 5, which is a non-wake-up (WuP) type.

[0145] Format 1130 may include an N-bit WuP signature 1132 and a non-wake-up MAC PDU fixed-length header 1134. The N-bit WuP signature 1132 may include a preamble clip field 1136 and a WuR ID field 1138. The non-wake-up MAC PDU fixed-length header 1134 may include a WuP OPT field 1140, a MAC header 1142, a data field 1144, and a CRC field 1146.

[0146] Format 1150 may include an N-bit WuP signature 1152 and a non-wakeup MAC PDU variable-length header 1154. The N-bit WuP signature 1132 may include a preamble clip field 1156 and a WuR ID field 1158. The non-wakeup MAC PDU fixed-length header 1134 may include a WuP OPT field 1160, a length field 1162, a MAC header 1164, a data field 1166, and a CRC field 1168.

[0147] In Type 5, the reason for wake-up is not mandatory. For example, a sensor operator may want to provide a modified calibration file to the sensor instrument to correct errors in previous sensing reports. The calibration file must be applied to the sensor before the next attempt to perform sensing. The calibration data may be transmitted within the MAC PDU, and the ZE-WuR may decode the calibration data and apply the calibration file to the PCR file path where the information resides. In an alternative example, the intended configuration for the sensor may need to be modified. The configuration file may be transmitted within the MAC PDU, and the ZE-WuR may write the configuration file to the secondary bank after verifying the CRC. The PCR is not woken up at this point. When there is an occasion where the PCR needs to be woken up, the presence of the information / command set in the secondary bank forces the PCR to respond to the information.

[0148] Figure 12 illustrates process 1200, which shows the wake-up type. In 1204, the WuR AP determines the WuP wake-up option via the preamble. In 1206, the ZE-WuR AP 1202 determines what the ZE-WuR may need to do following the wake-up (i.e., the wake-up operation).

[0149] In one embodiment, at 1208, the ZE-WuR AP1202 determines that the ZE-WuR needs to be woken up for a short duration. This sets the WuP OPT field to type 2. After making a subsequent determination that the PCR has been woken up, at 1212, the ZE-WuR AP1202 sends a data payload to the ZE-WuR. In a subsequent embodiment, the ZE-WuR AP may send two or more WuPs depending on the confidence estimate regarding the probability of successful reception of the previous WuP.

[0150] In another embodiment, the ZE-WuR AP determines that the PCR needs to be fully woken up. At 1210, the WuP OPT field is set to type 3. At 1214, the ZE-WuR AP1202 receives the pole PDU from the PCR. At 1212, the ZE-WuR AP1202 sends the data payload to the ZE-WuR.

[0151] In subsequent embodiments, the ZE-WuR AP may send two or more WuPs depending on the confidence estimate regarding the probability of successful reception of the previous WuP. The ZE-WuR AP waits for uplink transmissions from the PCR before participating in the data conversation.

[0152] In one embodiment, the ZE-WuR AP1202 determines that the PCR needs to be delayed but woken up in an opportunistic manner. The ZE-WuR AP1202 determines the maximum delay period before the PCR needs to be woken up. The ZE-WuR AP sends a WuP with the ZE-WuR OPT field set to type 4. The ZE-WuR AP1202 may send two or more WuPs depending on the confidence estimate regarding the probability of successful reception of the previous WuP.

[0153] In an additional embodiment, ZE-WuR AP1202 has data for PCR consumption. At 1216, ZE-WuR AP sets the ZE-WuR OPT field to type 5 and creates a MAC PDU with the data field embedded. The WuP containing the MAC payload is sent to ZE-WuR1218. ZE-WuR AP1202 may send two or more WuPs depending on the confidence estimate regarding the probability of successful reception of the previous WuP. At 1220, ZE-WuR AP1202 enters the PSM state.

[0154] Figure 13 illustrates a rough classification of WuP types in ZE-WuR1302. In one embodiment, ZE-WuR receives any WuP and considers it to be WuP type 1. ZE-WuR can choose to execute a synchronization procedure with the WuP.

[0155] In the second embodiment, at 1304, ZE-WuR1302 determines that the ZE-WuR AP has sent a ZE-WuR type 2 WuP and that it needs to be woken up for a short time. At 1306, ZE-WuR1302 wakes up PCR to indicate that the WuP type is type 2. After PCR is woken up, at 1308, PCR receives a short packet from the ZE-WuR AP and indicates successful receipt of the packet. It instructs ZE-WuR to return to ZE-WuR mode, and PCR returns to sleep mode.

[0156] In a further embodiment, the ZE-WuR 1302 determines that the PCR needs to be fully activated. This is done by detecting the WuP OPT field as type 3 transmitted in the WuP at 1310. At 1306, the ZE-WuR 1302 wakes up the PCR to indicate that the WuP type is type 3. As at 1312, the PCR sends a short pole PDU to the ZE-WuR AP indicating that it is ready to begin a data conversation. At 1308, the PCR receives and transmits in a series of conversations with the ZE-WuR AP until it determines that the conversation may be terminated. The PCR commands its ZE-WuR to return to ZE-WuR mode, and the PCR returns to sleep mode.

[0157] In a further embodiment, ZE-WuR AP1302 determines that its PCR needs to be delayed but woken up in an opportunistic manner. ZE-WuR1302 determines the maximum delay period before the PCR must be woken up. ZE-WuR1302 infers this by detecting the ZE-WuR OPT field set to type 4 in the WuP at 1314. In a further embodiment, ZE-WuR1302 determines an opportunistic opportunity in which it may choose to consume the payload and wake up the PCR. ZE-WuR1302 also determines the maximum delay period before the PCR must be woken up. If an opportunity to wake up the PCR arises, for example, if a different WuP of a different type is subsequently received, or if the maximum delay time has expired, ZE-WuR1302 wakes up the PCR and indicates the wake-up type as type 4. The ZE-WuR1302 passes the previously received payload in WuP type 4. The PCR can use the delayed wake-up indicator field to determine possible reasons why the PCR was woken up.

[0158] In an additional embodiment, at 1316, ZE-WuR1302 determines that it has received a WuP having a ZE-WuR OPT field set to type 5. At 1318, ZE-WuR1302 decodes the entire subsequent MAC PDU and verifies the CRC. ZE-WuR1302 decodes the data payload embedded in the data field within the MAC PDU and determines what needs to be done using that information. For example, at 1320, ZE-WuR1302 may write the contents of the MAC data field to a configuration file in the secondary data bank or replace an existing configuration file in the primary data bank. In this embodiment, ZE-WuR1302 does not wake up its PCR and returns to ZE-WuR1302 mode after successful consumption of the MAC PDU.

[0159] During the wake-up mode setup procedure, a ZE-WuR AP may indicate to the STA that it will use either a dedicated or shared resource to send its WuP. The STA configures the ZE-WuR with information about the shared / dedicated resource for receiving the WuP. One or more ZE-WuRs may be mapped to the same resource. The location where a WuP is sent to a given ZE-WuR may be a function of its selector identification information. During the wake-up mode setup procedure, the STA may be signaled a ZE-WuR seed and a ZE-WuR seed window, during which a certain type of WuP may be sent to that ZE-WuR. However, it should be noted that the ZE-WuR seed does not need to be resolved into periodic sensing / receiving periods. WuP transmissions may be aperiodic. The ZE-WuR seed window may be long or short.

[0160] The ZE-WuR seed indicates the starting position in the time frame in which a ZE-WuR WuP may be sent. The ZE-WuR seed window indicates the time range in which a ZE-WuR can expect to receive its WuP. Both the ZE-WuR seed and the ZE-WuR seed window are optional in that WuP transmissions can be completely aperiodic without granular time negotiation. WuP transmissions may be ad-hoc, on-demand, and autonomous for various reasons.

[0161] The ZE-WuR seed window length for a given ZE-WuR may be determined by the ZE-WuR AP based on requests and recommendations from the STA during the wake-up mode setup procedure. The window length may depend on the STA priority of the ZE-WuR(or)PCR component. For example, a higher priority ZE-WuR(or)PCR may have a shorter window. In other words, the ZE-WuR AP ensures a short window in which a WuP is transmitted when it actually needs to be transmitted. A lower priority ZE-WuR(or) with higher waiting capability may be given a longer seed window. A lower priority ZE-WuR may have to wait a longer duration within the seed window to get its turn for a WuP if required by the ZE-WuR AP. The position and frequency resources assigned to a ZE-WuR may be changed or modified by the ZE-WuR AP during any subsequent reassociation or ZE-WuR mode modification procedure.

[0162] Figure 14 shows exemplary dedicated resources for multi-tone wake-ups. As shown in Figure 14, the ZE-WuR AP determines that ZE-WuR1402a, 1402b, 1402c and / or 1404d are allocated dedicated resources from which their respective WuPs can be transmitted. One or more frequency resources at different times may be used by the ZE-WuR AP as opportunities to transmit WuPs. In Figure 14, ZE-WuR1 1402a refers to a dedicated location / resource from which ZE-WuR1 can expect to receive its WuP. ZE-WuRS1404 refers to a common WuP for several low-function ZE-WuRs whose frequency use is restricted. ZE-WuRS1404 may be used as a common WuP for low-function ZE-WuRs to perform synchronization and also as a group wake-up signature.

[0163] Figure 15 illustrates an exemplary shared resource for multitone wake-up. As shown in Figure 15, a ZE-WuR AP may determine that ZE-WuR1502a, 1502b, 1502c, and 1502d are assigned a shared resource from which their respective WuPs can be transmitted. One or more frequency resources at different times can be used by a ZE-WuR AP as an opportunity to transmit WuPs to one or more ZE-WuR1502a, 1502b, 1502c, and 1502d. In Figure 15, ZE-WuR1, 4, and 6 1502a refer to a shared location / resource from which ZE-WuR1, 4, and 6 1502a can expect to receive their WuPs. Disambiguation of which ZE-WuR is addressed depends on the WuP signatures transmitted in those shared resources. Similar to Figure 14, ZE-WuRS1504 in Figure 15 is a common WuP location for several low-function ZE-WuR1502a, 1502b, 1502c, and 1502d whose frequency usage is restricted. Note that in Figure 15, ZE-WuR3 1502c may be assigned a dedicated resource, while the other ZE-WuR1502a, 1502b, and 1502d may be assigned a shared resource. Also note that the figure shows a multi-tone scenario in which one or more frequency tones are determined by the ZE-WuR AP for WuP transmission. Associated tone-ZE-WuR pairings may be determined by the ZE-WuR AP in conjunction with the requirements and capabilities indicated by the STA during the ZE-WuR mode setup procedure. A ZE-WuR assigned a dedicated resource may be switched to a shared resource during the sub-sequence ZE-WuR mode modification procedure (or) the re-association procedure, and vice versa.

[0164] Figure 16 illustrates an exemplary shared resource for single-tone wakeup. Figure 16 is similar to Figure 15, except that in single-tone wakeup, the WuP AP supports WuP transmission in only one set of frequency tones.

[0165] The WuP AP determines the time / frequency resources necessary to enable wake-up functionality in the network. The ZE-WuR AP configures the set of time / frequency resources for receiving WuP at each STA that requires wake-up functionality. Resources are configured during the association and wake-up mode setup procedures. Each STA configures its respective ZE-WuR using the WuP signature and the time / frequency resources at which the WuP signature can be received.

[0166] Figure 17 illustrates exemplary resource determination for WuP transmission. As shown in Figure 17, the ZE-WuR AP determines that it needs to transmit a WuP to the ZE-WuR. In 1702, the ZE-WuR AP determines the time / frequency resources previously allocated to the ZE-WuR (via STA) during association (or) wake-up mode setup. In 1704, the ZE-WuR AP selects one or more tones to embed the WuP signature. In 1706, if the ZE-WuR has been allocated dedicated resources, in 1708, it selects a separate ZE-WuR signature from a number of pre-configured ones for the ZE-WuR and transmits the selected WuP for the ZE-WuR.

[0167] If shared resources are allocated to a ZE-WuR, in 1710, a shared WuP may be selected to address one or more ZE-WuRs that share those resources. In 1712, the selected preamble may be signaled to the WuR STA. Note that the WuP may incorporate a hierarchical scheme to address all or a subset of the ZE-WuRs that share those resources. In 1714, before sending the WuP, the ZE-WuR AP determines the selector identifier of the ZE-WuR and the hierarchy that needs to be encoded in the WuP signature. The WuP seed and WuP seed window may be configured in advance by the ZE-WuR AP (via the STA) in the ZE-WuR during the association and / or wake-up mode setup procedure.

[0168] In 1716, the ZE-WuR may have a wake-up seed and seed window configured by its STA. Some ZE-WuRs may have a short seed window, while others may have a longer seed window length.

[0169] Figure 18 illustrates the seed and seed window for WuP transmission. ZE-WuR#3 has a seed window 1804 that may be shorter than, for example, the seed window 1802 of ZE-WuR#2. This means that, starting from the beginning of the WuP seed indicated for ZE-WuR#3, ZE-WuR#3 can be expected to receive its WuP within the expiration of a window that may be significantly shorter than the window for ZE-WuR#2. The ZE-WuR AP determines the window length based on, for example, the latency of channel access due to DCF, and / or the priority / urgency of needing to wake up ZE-WuR#3. By the same logic, the priority of ZE-WuR#2 may be lower (in the illustrative diagram of Figure 18), which means that STA#2 may be allowed to receive an additional delay before a successful wake-up.

[0170] While determining resources for WuP transmission, the ZE-WuR AP may leave adjacent tones empty so that a power boost may be applied on the tone carrying the WuP. Since all WuPs are Type 1 in addition to incorporating additional types, the ZE-WuR correlating the WuP autonomously determines the rate at which its crystal oscillator requires control. The ZE-WuR controls its clock using the preamble clip portion of the WuP signature of any WuP signature. In addition to this, if the WuP is addressed to itself, the ZE-WuR can adjust the clock in addition to correlating and decoding the rest of the WuP. The ZE-WuR OPT of a WuP allows the ZE-WuR to (1) partially decode the PHY PDU, (2) fully decode the PHY PDU including the headerless control element, (3) ignore the MAC PDU, or (4) decode the MAC PDU. Subsequently, using the programmed principles, one of several possible actions is taken by the ZE-WuR, one of which is to wake up its PCR. The ZE-WuR's WuP slot may be modified at any time by the ZE-WuR AP during the reassociation or wake-up mode modification procedure. The ZE-WuR AP may determine the need to rebalance the network and reallocate dedicated / shared resources for the various ZE-WuRs.

[0171] A ZE-WuR AP can decide to power boost the tone carrying a WuP and leave adjacent tones either powerless or at reduced power. A ZE-WuR AP may support power boosting to enable a ZE-WuR that can harvest energy from the reception of signals with higher energy tones. Through this method, a ZE-WuR AP not only increases the probability of successful WuP reception by the target ZE-WuR, but also facilitates energy harvesting by a ZE-WuR that opportunistically receives WuPs. A ZE-WuR AP can determine typical response latency and the reasons for response latency when attempting to wake up a PCR. The ZE-WuR AP first wakes up the ZE-WuR by sending several WuPs (a pack of WuPs). The pack size may be dynamic, deployment-specific, and does not need to be fixed. The ZE-WuR AP determines the potential for subsequent wake-up latency in ZE-WuR by inferring the information sent back by PCR.

[0172] Upon receiving a WuP in the WuP pack, the ZE-WuR wakes up the PCR. The ZE-WuR also indicates to the PCR the number of WuPs received so far in the pack. The woken-up PCR then estimates, for example, channel access latency due to DCF. The number of positively counted WuPs in the WuP pack and the access latency are determined immediately before the PCR sends a message to the ZE-WuR AP.

[0173] Figure 19 shows how the ZE-WuR AP can estimate the probability of receiving a WuP by ZE-WuR and the delay / congestion of channel access by PCR. Since ZE-WuR AP1902 knows the pack size, it also determines the offset from the first positive decoding of the WuP by ZE-WuR1904 and the latency experienced during channel access. These estimations are performed periodically or opportunistically by ZE-WuR AP1902 to fine-tune the WuP pack size and the congestion present in the system. ZE-WuR AP1902 can also use this information to re-equalize WuP allocations (e.g., reducing group size to WuP allocations) and then determine the WuP pack size to use by comparing it to the previous WuP pack size.

[0174] For example, a WuP used to wake up a group of ZE-WuRs may wake up each of their PCRs at roughly the same time that they perform channel access to poll ZE-WuR AP 1902. The larger the group size, the greater the latency in access for STAs within the group, as they may have to perform clear channel assessment / DCF before accessing the channel to contact ZE-WuR AP1902.

[0175] In one embodiment, the ZE-WuR AP may receive priority for requested ZE-WuR functions and services from the STA during the establishment of association, wake-up mode setup, re-association, or wake-up mode modification procedures. The ZE-WuR STA requests one or more WuP signatures for the wake-up procedure. The ZE-WuR AP may determine the relative priority of ZE-WuR STAs in the system among various ZE-WuR STAs and determine whether the STA should be given a shared or dedicated resource to listen for WuP signatures. In this embodiment, if a dedicated resource is allocated to the ZE-WuR STA, one or more WuP signatures are presented to the ZE-WuR STA. The PCR component of the STA constitutes the ZE-WuR with the allocated WuP signatures. The ZE-WuR AP uses the specific WuP signatures and sends them to the ZE-WuR on the dedicated resource to perform a function-specific wake-up of the PCR.

[0176] In another embodiment, the ZE-WuR AP allocates shared resources to the ZE-WuR STA during the establishment of an association, wake-up mode setup, re-association, or wake-up mode modification procedure. The ZE-WuR AP may use the same set of resources to send a WuP to wake up one or more ZE-WuRs that share those resources. In this embodiment, when the ZE-WuR AP decides to allocate shared resources, it also decides to allocate an appropriate WuP signature to the ZE-WuR to minimize group wake-up when not necessary. The ZE-WuR AP encodes the hierarchical information in the WuP to facilitate the shared ZE-WuR skipping decoding when the hierarchy is broken. The ZE-WuR may be assigned a selector ID, and the hierarchy may be encoded according to the priority among the ZE-WuRs within the group. For example, in a group of ZE-WuRs (1, 3, 5), assume that ZE-WuR 1 has a higher priority than both ZE-WuR 3 and 5, and ZE-WuR 3 has a higher priority than 5. The WuP signature encodes a hierarchy that allows ZE-WuR 1 to skip decoding much earlier than ZE-WuR 3 and 5 when the WuP is not addressed to it. Assume that in an N-bit WuP signature, the last J bits are used to indicate the hierarchy. The (N-J) bits are decoded by all of ZE-WuRs 1, 3, 5. However, in ZE-WuR 1, it is necessary to decode j≦J bits to detect that the WuP is not addressed to itself, while in ZE-WuR 3, it is necessary to decode (j + d)≦J bits to detect that the WuP is not addressed to itself, and finally in ZE-WuR 5, it is necessary to decode up to a maximum of (J + d + e)<J bits to determine that the WuP is not addressed to itself.

[0177] In a further embodiment, the ZE-WuR AP determines a set of tones to be applied to one or more ZE-WuRs into which the WuP is embedded for transmission. The ZE-WuR AP may select multitones for transmitting the WuP by allocating a dedicated frequency resource to each ZE-WuR. The dedicated resource is mapped to each ZE-WuR. The ZE-WuR AP may leave adjacent tones in the WuP transmission for null transmission. In the following embodiments, the tone carrying the WuP is power-boosted, and tones adjacent to the WuP tone are transmitted at zero or reduced power. Power boosting may be applied by the ZE-WuR AP to increase the reliability of WuP reception and to enable energy harvesting by possible ZE-WuRs.

[0178] In the relevant embodiments, the ZE-WuR AP determines a set of tones to be applied to one or more ZE-WuRs into which a WuP is embedded for transmission. The ZE-WuR AP can select multitones for transmitting a WuP by allocating a shared frequency resource to various ZE-WuRs. A set of one or more ZE-WuRs may be allocated the same frequency resource to which a WuP can be transmitted. The ZE-WuR AP may leave adjacent tones in the WuP transmission for null transmissions. In the following embodiments, the tone carrying the WuP is power-boosted, and tones adjacent to the WuP tone are transmitted at zero or reduced power. Power boosting may be applied by the ZE-WuR AP to increase the reliability of WuP reception and to enable energy harvesting by possible ZE-WuRs.

[0179] In one embodiment, a ZE-WuR AP can rebalance a ZE-WuR previously assigned to either a dedicated or shared resource to another resource. The ZE-WuR AP may choose to rebalance a ZE-WuR to use a different resource, either to allow the STA to request such action during a reassociation or wake-up mode correction procedure, or by self-determining the need to rebalance the load. A ZE-WuR assigned to a dedicated resource may be grouped with other ZE-WuRs, and previously grouped ZE-WuRs may be moved to use the dedicated resource. In another embodiment, the ZE-WuR AP then configures ZE-WuR selector identification information on an STA configured on that ZE-WuR by the STA. The selector ID can be used by the ZE-WuR to determine the hierarchy that may be applied while decoding a WuP. In this embodiment, the selector ID may be assigned to an STA assigned to a shared resource for receiving WuPs. It is implicitly determined that a ZE-WuR having an assigned selector ID can also be part of a group.

[0180] In additional embodiments, the ZE-WuR AP determines the priority of the STAs and the wake-up priority based on parameters exchanged during the association request or wake-up mode request. In this embodiment, higher-priority STAs may be given a shorter window during which they are guaranteed to receive a WuP, while lower-priority STAs may be given a longer window during which they can expect their WuP. The nominal seed may consist of a ZE-WuR AP that indicates a potential start time during which the ZE-WuR may become more sensitive to WuPs. In this embodiment, the windowed duration indicated by the seed window starting from the seed can be defined as a time frame during which the ZE-WuR AP is intended to send a WuP to the appropriate ZE-WuR.

[0181] In 802.11ba, ZE-WuR consists of discovery channel information. The intent of the feature may be to allow the STA to detect the absence of a periodic beacon and then search for the presence of a nearby ZE-WuR AP. In addition, even during service, ZE-WuR may choose to remain associated with the serving ZE-WuR AP and monitor the discovery channel outside of service periods. In the proposed solution, neighboring AP information may be configured by the serving ZE-WuR AP as a discovery packet to the associated ZE-WuR STA during the association or wake-up mode setup procedure. In one embodiment, the ZE-WuR AP cooperates with other APs in the BSS / ESS to assign one or more WuP signatures to the STA. The preamble clip may be part of the WuP signature, as previously described. One of the more preamble clips used by neighboring ZE-WuR APs in the BSS / ESS may be configured in ZE-WuR by the currently associated ZE-WuR AP. An associated discovery channel with a preamble clip may be included in the discovery packet. The PCR component of the STA constitutes this information in its ZE-WuR component. This could be a use case, for example, in an offshore oil drilling rig where there are multiple offshore-deployed crest sensors that can float and move arbitrarily over a reasonable over-age area that can be serviced by a collection of APs. Floating may take the form of Brownian motion or any form bounded only by a barrier deployed at the furthest edge of the oil drilling boundary. In such a use case, when a sensor moves from capturing one AP to capturing another AP, it simply does not need to perform any significant task to accommodate the movement.

[0182] A serving AP can configure a discovery PDU that lists preamble clips used by other neighboring APs and their movement to anywhere within a larger area bounded by a barrier. Any AP may be able to wake up a sensor if the sensor is configured with the correct preamble clip and coordination between APs.

[0183] Figure 20 illustrates an exemplary preamble clip to facilitate ZE-WuR discovery. The packet may include an Element ID frame 2002, a length field 2004, an Element ID Extension field 206, and a Neighboring AP Information field 2008 (i.e., the discovery packet). As shown in Figure 20, the discovery packet includes a WuR Class field 2020, a Channel Information field 2022, an AP ID field 2024, and a BSS / ESS ID field 2026. The discovery packet is also applicable within the BSS / ESS and carries a WuP signature 2028 that signals to the WuR. Either an explicit signature is assigned, or the relevant AP constructs seed information for the WuR to derive such information. In one embodiment, the WuP signature carries a preamble clipping portion and ZE-WuR identification information specifically assigned to the ZE-WuR by the neighboring AP in the BSS / ESS. Such neighbor details, one to P for each channel, may be configured in the STA. For each channel, 1 to R APs that the ZE-WuR can discover are identified in the discovery packet. Before entering sleep mode, the STA configures the discovery packet information received by its ZE-WuR.

[0184] In another embodiment, the ZE-WuR monitors for the presence of neighboring APs detailed in the discovery packet. The ZE-WuR may choose not to monitor for WuPs from neighboring APs configured in the discovery packet if the serving ZE-WuR AP can still be considered to be serving the ZE-WuR. This may be done, for example, by monitoring for the presence of beacons and WuPs. In one embodiment, when the ZE-WuR moves away from its location and into the service area of ​​a different ZE-WuR AP, it correlates for WuPs using previously configured discovery packet information. In that embodiment, upon identifying an AP on a particular channel, if the WuP signature was previously configured for the ZE-WuR by the previously serving ZE-WuR AP, the ZE-WuR refrains from associating it with the new ZE-WuR AP until it is needed in the future. This need may arise, for example, when the ZE-WuR needs to wake up its PCR to receive or transmit data packets.

[0185] In another embodiment, when a ZE-WuR discovers itself in the presence of a new AP, it does not need to reassociate until it is instructed by the new ZE-WuR AP to wake up its PCR. The command to wake up may be executed by receiving a WuP from the new AP, but using information previously configured for the ZE-WuR by its previously associated ZE-WuR AP. This may be useful because the PCR may be a less active 802.11 device and only needs to be woken up once every few days for sending or receiving a few packets. In an additional embodiment, when the ZE-WuR receives a WuP from the new ZE-WuR AP, the ZE-WuR wakes up its PCR, indicating the AP identification information and the WuP as the reason for the wake-up. The PCR can then be reassociated with the new ZE-WuR AP. The newly serving ZE-WuR AP can erase, add, or modify the discovery packet configuration in the STA. The ZE-WuR can monitor WuP frames during the ON window and perform scans only during the OFF window.

[0186] In yet another embodiment, a ZE-WuR AP may constitute a ZE-WuR with different types of discovery packets. The ZE-WuR AP displays neighbor AP information and relative capacity. The ZE-WuR AP may also display the allow threshold for neighbor APs. One-to-one neighbor AP information may be configured within the discovery packet in the ZE-WuR. The number of active APs on each channel may also be indicated in the discovery packet. The higher the AP count, the higher the probability of finding neighbor APs on the indicated channel. However, it may also indicate a decrease in capacity and an increased probability of rejecting association at those APs. In an additional embodiment, the ZE-WuR AP displays the relative capacity and allow threshold for each BSSID in the STA. The relative capacity and allow threshold for each previously provided neighbor information may be erased, added, or modified by the serving ZE-WuR AP when PCR may be active. This information may be updated by the serving ZE-WuR WP during wake-up mode setup, update, or beacon transmission. The allow threshold refers to a threshold below which a candidate AP is likely to reject the association request. The threshold may be a Boolean value that signals a binary "accept / reject" instruction to the ZE-WuR to which association is desired. The threshold may also be configured as a percentage indicating that the relative capacity must be higher than the signaled threshold.

[0187] Figure 21 illustrates an exemplary discovery packet 2108. Similar to Figure 20, the packet may include an element ID frame 2102, a length field 2104, an element ID extension field 2106, and an adjacent AP information field 2108 (i.e., the discovery packet). The discovery packet may include a WuR class field 2120, a channel information field 2122, an AP ID field 2124, and a BSS / ESS ID field 2126. The BSS / ESS ID field 2126 may include a relative capacity field 2130 and an allow threshold field 2132. For example, a relative capacity of 40% and an allow threshold of 10% indicates that ZE-WuR is likely to succeed when the association request is sent to the AP. Conversely, a relative capacity of 30% and an allow threshold of 35% indicates that ZE-WuR is unlikely to succeed when the association request is sent to the AP. ZE-WuR uses configured discovery packet information to rank candidate APs based on a combination of relative capacity and permission thresholds. Higher-ranked APs may be better suited for channel access in systems based on DCF access. The actual candidates for ZE-WuR will depend on the APs in the direction of ZE-WuR's movement.

[0188] The following describes proposed improvements to the 802.11 frame format to effectively enable ZE services, including power delivery and energy harvesting. The present invention defines a conceptual framework for ZE device receivers having battery-less operation, or devices equipped with small temporary energy storage devices.

[0189] Temporary storage devices may include specific low-charge (low-capacitance), fast-chargeable, temporary miniature batteries or other forms of energy storage devices. High-level design and optimal operation issues of receivers may depend on two key variables during reception operation: namely, incident signal strength (power level) and current energy storage level (in temporary / temporary storage). Device operation may be characterized with respect to conceptual fundamental thresholds governing its receiver operation. Depending on the stage of reception processing while receiving ZE frames, and based on a PHY frame structure very similar to that specified in the 802.11ba-WuR specification, an active ZE (WuR) receiver may be in one of two basic states: (1) signature / synchronous field detection, i.e., searching / listening to ZE synchronous sequences or ZE signature sequences, and (2) data frame decoding / reception.

[0190] The region of operation (ROO) planes associated with each state are very similar, except for the thresholds considered; therefore, only the ROO plane associated with the state of the first receiver is discussed.

[0191] Figure 22 illustrates an exemplary operating region for energy harvesting. When a battery-less ZE receiver or a receiver with a small temporary energy storage device is operating in state 1, the receiver has power consumption requirements to operate its logic circuitry, collect power from the input signal, and supply it to the signature( / synchronous) detector in order to reliably detect the signature with a false detection probability below a low, pre-set threshold. If the power harvested from the incident signal itself is used to power the circuit, this incident power may have to be divided between the detector input port and the power harvester at a certain rate. The harvesting circuit can power the circuit indirectly by supplying power directly to the temporary energy storage device. Sequence detection threshold: Assuming that none of the incident power is used to power any receiver circuitry, all of this can be directed to the signature sequence detector input. A base threshold, sensitivity threshold, or sequence detection threshold can be conceptualized for the input power, which may be the minimum signal power level for reliable detection of the signature (as declared by a pre-set criterion). This can be shown by the vertical line 2202 on the ROO plane in Figure 22.

[0192] Another area is the minimum energy reserve required for operation. Even "battery-less" devices may have some form of temporary energy / charge storage to power the receiver circuit during receiver operation, because (without this temporary reserve) the instantaneously harvested energy may not always be able to supply the power required by the circuit throughout its entire operating period [the instantaneously harvested energy supply may not always keep up with the power demands of the circuit]. Therefore, a minimum level of reserve to be maintained in this storage device (sometimes called an energy buffer) may be required to allow any operation of the receiver to proceed. This threshold may be the "minimum energy reserve required to operate the signature detector." This threshold is indicated by the horizontal line 2204 on the ROO plane in Figure 22.

[0193] There may be two soft thresholds for the incident signal power, where energy harvesting from the incident signal may roughly begin. Significant energy harvesting can only be properly performed at signal levels above this threshold; meaningful or significant energy harvesting cannot be achieved at lower signal levels. One such threshold may occur when 100% of the incident power is directed to the energy harvester (this may be called a standalone EH threshold), and another such threshold may occur when EH is performed concurrently with a sequence detector, i.e., more specifically, when an amount of power equal to a “sequence detection (sensitivity) threshold” is divided towards the detector input.

[0194] Because clearly defined thresholds around such definitions may not be visualized, these thresholds may be soft and may even be embodied by fuzzy bands of power levels. As shown in Figure 22, these thresholds are vertical lines (dotted lines) or bands in a plane. Such EH thresholds may not exist at all, as conceptualized in this section. It may be feasible to harvest some energy to varying degrees across the entire range of verifiable input signal levels. Another assumption here that should be continuously evaluated and verified is that the EH threshold(s) are greater than the fundamental signal detection threshold.

[0195] Another area is the minimum energy storage required to operate the detector without EH. Near the region where only sufficient incident power is available to turn off the signature detector (i.e., near the sequence detection threshold), the ZE receiver idealization can direct 100% of the incident signal power to the detector input. In such scenarios, a sufficient energy storage level may be required to power the detector circuit until the end of the detection process. The minimum level of stored energy required to successfully operate the sequence detector to a reasonable conclusion while operating at the incident signal power level at the sequence detection threshold can be called the threshold for the "minimum energy conservation required to operate the sequence detector without EH." "Running the sequence detector to a reasonable conclusion" can be defined as either successfully running the sequence detector over a reasonable amount of time (e.g., to at least detect a complete valid signature), or initiating the signature detection process with a reasonable opportunity to complete the process.

[0196] In the region of incident power levels that do not produce significant EH (i.e., below the EH threshold), the minimum energy storage level required for detector operation may gradually (and slowly) decrease as signal intensity increases. This is because higher signal intensity may mean greater robustness, higher reliability, or earlier detection (which may require a lower energy storage level at the start), or a stronger signal may facilitate the processing required to successfully detect the sequence (which reduces the power requirements of the processing circuit), or the need for retries decreases, increasing the probability of successful signature detection. Furthermore, the device is capable of micro-energy harvesting even in this region, which reduces the required load on stored energy storage in the early stages of sequence detection as the incident signal intensity increases. Thus, this threshold is nearly horizontal, with a slight downward slope to the left of the ROO plane.

[0197] When the EH threshold is exceeded, the receiver can harvest energy, and any surplus available power from the incident signal can be diverted towards the EH. In an idealized ZE receiver, this functions similarly to an overflow gate that directs all power up to a sequence detection threshold to the detector input, but any power exceeding this threshold is directed entirely to the EH circuit. The receiver receives sufficient incident signal power to reach an operating region where it balances the power requirements of its circuit with the surplus energy that can be harvested from the received signal. This is the threshold at which a break-even occurs between energy consumption and capture, and it is the point at which the receiver can close its energy budget without assistance from an internal energy storage device.

[0198] In the ROO plane, the region in which the receiver operates with nearly zero balance of excess energy from its energy harvesting is represented by a narrow vertical band of incident signal levels. Between the EH threshold and the energy sufficiency break-even threshold, the threshold curve depicting the region in which successful sequence detection can proceed is likely to be a curved, downward-sloping arc. Above this arc is the region in which sequence detection can be performed partially dependent on the battery / energy storage device, along with some energy harvesting. Below this arc is the region in which the energy storage level may be too low to operate the detector, but this region is useful for pure energy harvesting.

[0199] This threshold curve may tend to drop sharply as the energy storage level requirement decreases significantly, since more energy becomes available from harvesting as the signal level increases. Excess power may exist available from harvesting from the incident signal in the final region on the right side of the plane in Figure 22. Here, the threshold curve forming the lower boundary of the region can slope gently downward with the increased available power from EH, allowing the receiver to reduce its reliance on the energy storage device. The threshold for the "absolute minimum energy storage required to operate" may also decrease as the incident power level increases. As the rate of energy supply increases, the required energy buffer can be made smaller.

[0200] Similar to the sequence detection state of a ZE receiver, ROO can be visualized when operating in an information / data decoding state. The threshold for detection sensitivity, in this case decoding sensitivity, may be at least somewhat higher than the corresponding threshold for sequence (signature) detection. Similarly, the EH threshold with simultaneous decoding can be a bit offset from this threshold in the sequence detection state, and may be a higher bit in the case of a receiver in an information decoding state.

[0201] The signature detector does not need to rely on an external energy storage device, and its threshold for the "minimum energy storage required to operate" can be approximately zero, particularly due to the specific nature of the energy signature sequence outlined above. The EH threshold drawn on this ROO plane in Figure 22 is for the energy storage device used by the data decoder circuit within the receiver. In this device scenario, this threshold may also be indicated by a band of incident signal levels, meaning it indicates an ambiguous range of values ​​rather than an exact threshold. In this case, the standard signature detection threshold does not require stored energy from the main energy storage device that continues to power the receiver's data decoding operation. Thus, this threshold is shown by a solid line in Figure 22. However, to allow for a theoretical scenario in which the signature detector may be provided with the assistance of a battery or temporary storage, and which may enable the detection of signatures at lower signal levels, a co-threshold relative to the main signal detection threshold is conceptualized. This is shown by a dotted line to the left of the main threshold (indicating lower incident power) in Figure 22.

[0202] An infrastructure network may include Energy Delivery (ED) nodes, access points (APs), and ZE STAs, which are members of the network. The architecture can be based on APs (and, where applicable, separate ED nodes) connected to a wired infrastructure network (similar to a WLAN distribution system - DS), or on a mesh architecture where APs and potentially ED nodes are linked to each other via wireless "backhaul links." In most system designs, APs can also function as energy sources (ED nodes) because ED waveforms are transmitted on the same channel as information packets. In addition, there may be infrastructure nodes whose sole purpose may be to function as energy sources. The main principle of having separate, dedicated ED nodes is that they may be appropriately positioned for more efficient energy transfer to specific ZE STAs. In addition, they may be involved in beamforming of ED transmissions, either in single-point beamforming independent of any other transmitting devices, or in coordinated beamforming where two or more transmitters coordinate their transmissions to concentrate power on the intended receiver.

[0203] If there are dedicated ED nodes that do not function as APs for information exchange with non-AP STAs, they may need to exchange control information or signals with the main network and APs that operate in coordination with them. If dedicated ED nodes are connected to a DS wired network, all necessary exchanges of control signals (e.g., timing of ED transmissions, identification of the intended recipient of the ED) can be exchanged via the DS. Similar to mesh APs, there may be 802.11 mesh architectures having a set of dedicated ED nodes that are part of a mesh. If dedicated ED nodes are part of a mesh architecture, they can communicate with the network via wireless links; that is, a wired backbone connection to the ED nodes may not be necessary. Modifications to the MAC protocol may be proposed for the communication of necessary control information from the network to the dedicated ED nodes. This essential control information enables the ED nodes to properly target, time, and synchronize their ED transmissions to intended ZE STA recipients, and to time them in relation to key information communications to those ZE STAs.

[0204] A single energy delivery source refers to a situation where each ZE STA is served for its EH needs by a single energy source (ED node). It may be possible for the same AP that sends information packets to the ZE STA to also serve the ED. If the ED node for the ZE STA is isolated from its information exchange AP, and any dedicated POW frames, waveforms, or fields that are part of the PHY frames used solely for the ED need to be transmitted in a manner coordinated with data packets in terms of time and frequency, then the ED node serving the STA must coordinate its ED transmissions with data transmissions (or receptions) from the AP.

[0205] "Multiple energy delivery sources" refers to cases where any individual ZE STA can be served by multiple ED nodes due to its energy harvesting needs. Each ZE STA may have an "active set" of ED nodes that serve it for EH. In systems that allow for some mobility, the active set of a ZE STA may be updated from time to time. Multiple ED nodes within the active set of a ZE STA can participate in coordinated ED to the STA through techniques such as coordinated beamforming of ED signals. It may also be possible to employ a "best choice" strategy to select an ED node from the active set at any given time. Coordinated beamforming may require finer timing matching, which will require a synchronous clock across all these ED node transmitters, in addition to matching their transmit times on the same slot boundary, as the involved transmitters may need to precisely match the phase of their waveforms. This should require pre-set transmit start times across all these ED nodes for beamformed ED transmission.

[0206] The current frame format is insufficient to provide the energy required for WUR-Data decoding. Furthermore, legacy preambles may not be optimal for EH purposes, and the WUR-Sync field duration may be insufficient to harvest a significant amount of energy. WUR may not be harvestable while attempting to detect WUR frames, i.e., while searching for the WUR-Sync field.

[0207] Figure 23 shows the durations of various fields, including both fixed-length (FL) and variable-length (VL) fields. Three different modification options are presented to enable simultaneous delivery of information and energy. Each of these is described above.

[0208] Figure 24 illustrates Option 1. In Option 1, the frame format includes the legacy preamble 2402 and WUR-Sync 2404. The frame format may be modified to include the Power Optimized Waveform (POW) preamble 2406 after WUR-Sync 2404. Given a 4ms MCOT and a maximum WUR frame duration of 2.972ms, a fixed POW preamble length of approximately 1ms can be readily adapted. In 802.11, the MCOT may be limited by the communication bandwidth and priority class. In the 5GHz band, the MCOT may be limited to 2ms, 4ms, or 6ms depending only on the channel access priority class.

[0209] Figure 25 illustrates Option 2. Similar to Option 1, the WUR frame may include the legacy preamble 2502, WUR-Sync 2504, and POW preamble 2506. Dedicated EH frames 2508a and 2508b may precede the WUR frame. In one scenario, the AP may contend for the channel at least twice before delivering the WUR frame. Contention may be necessary to gain access to the media. In this option, the WUR must hold harvested energy long enough for the AP to contend for the channel and deliver the WUR frame. Also in Option 2, the WUR frame may have a higher access category than the EH frame.

[0210] Figure 26 illustrates Option 3. The WUR frame may include a ZE preamble 2202 and a legacy frame 2604. An EH indication preamble 2608 may be introduced in precedence over / before the legacy frame 2604. The AP must compete for the channel at least twice before delivering the ZE frame, exactly as in Option 2. The ZE frame can deliver only information according to the legacy IEEE 802.11ba WUR frame structure, or it can deliver both power and information according to the frame structure proposed in Option 1. Another variation of the frame structure in Option 1 is shown in Figure 26, where the ZE preamble 2202 precedes the rest of the frame to indicate the availability of power delivery for a certain duration, for example, the duration may be indicated by the preamble itself before the field delivering information to the WUR. Furthermore, to ensure synchronization for accurate information decoding as in Figure 26, a ZE-data field 2612 may be present immediately after ZE-Sync 2610. A new variation of the ZE frame structure enables the simultaneous delivery of information and energy, where ZE-Sync2610 may be optional based on the synchronization capability of devices using, for example, the ZE preamble 2602, as well as the need for resynchronization after a duration that may be shorter than the overall duration of the legacy preambles 2614 and POW2616.

[0211] When designing WUR-sync or ZE-preambles for "harvest or detect" and / or "harvest then detect / decode" architectures, two broad designs may be considered. One design may require no changes to the existing WUR-Sync design, which may have some potential negative impacts on legacy / existing WUR architectures. The second design, on the other hand, introduces changes to the existing WUR-sync, leading to more efficient integration with legacy / existing WUR.

[0212] In one embodiment, no changes may be required to the legacy WUR. However, the legacy WUR may be able to detect WUR frames containing the new power delivery field, but may not be able to decode the data field within the frame. On the other hand, the new WUR will be able to detect the new WUR frame, harvest the energy, and then decode the data field. However, the new WUR may still fail to decode any legacy WUR frame that does not contain a power delivery field with POW. This design may impose a burden on the AP to handle the distinction between legacy and new WURs and generate / transmit the corresponding WUR frames accordingly. A drawback of such embodiments is the power consumption overhead associated with decoding additional WUR frames that are not targeted by the WUR.

[0213] In another embodiment, a new WUR-Sync design may be considered in which the legacy WUR does not detect energy harvesting frames (e.g., dedicated frames for energy harvesting or WUR frames containing new power delivery fields), and the new WUR can distinguish between legacy WUR frames and new WUR frames. This embodiment may then lead to power consumption savings through the WUR's ability to ignore data decoding when it is unnecessary or not targeted at the WUR itself.

[0214] Consider a new WUR function that distinguishes between WUR frames dedicated to power delivery / energy harvesting, WUR frames intended for simultaneous power and information delivery, and information only. The new WUR may have the freedom to choose whether to miss an energy harvesting opportunity or an information decoding opportunity based on the current charge level of the WUR's battery.

[0215] A potential WUR-sync design could utilize the current IEEE 802.11ba WUR-Sync code structure, where the basic sequence S is followed by its complement (1-S). The obvious advantages of this approach are that the transmit capability is supported with minor modifications and WUR can still use a single collimator. The disadvantage is that, if the first positive peak is not considered, legacy WUR may misinterpret the second negative peak as an HDR WUR frame. This may necessitate modifications to the detection circuitry or become a requirement for legacy WUR. Without this modification, legacy WUR may consume more power during EH frame transmission.

[0216] For ZE devices, the feasibility of persistent communication depends on energy regulation. Even in existing architectures, it is predictable that auxiliary and alternative energy sources will be used to maintain electronic functionality in the circuit. However, cost can be a significant factor limiting the alternative / redundant mechanisms that can be incorporated. In one architecture, instead of relying on alternative sources, an additional storage device may be relied upon. When energy is harvested, the energy is stored in an energy storage device that retains capacitance over a longer duration. Even when no energy is consumed, the capacitor consumes energy at some nominal rate, depending on the quality of the electronic component.

[0217] Therefore, if the energy harvesting rate is very high, the energy storage may not be sufficient, and auxiliary storage may be required. In one architecture, two different energy storage devices (batteries) may be used, one nominally used, for example, for decoding information, and the other storage device having a much smaller capacity than the nominal storage device. The second storage device may be called an auxiliary storage device. The auxiliary storage device can be charged very quickly and, being the highest priority task in the architecture and the most commonly performed procedure, may be dedicated solely to the sequence detector. The auxiliary storage device may be a device exhibiting a very high input impedance. As detailed in the previous section, the energy signature may contain a POW structure sufficient to enable signature (sequence) detection, which can be done without the assistance of other batteries. This may be sufficient to help charge the energy storage device of the sequence detector simultaneously to detect itself, or the signature sequence may be prefixed with a short POW that helps charge the storage device used for sequence detection.

[0218] While implementation details can vary, it may be useful to visualize the harvesting scheme as a state-machine implementation. Generally, the two can be considered at two levels: (1) the energy harvesting level and (2) the non-energy harvesting level. Figure 27 shows the energy harvesting and non-energy harvesting levels.

[0219] As shown in Figure 27, at non-energy harvesting levels, sufficient storage devices may be available, and therefore, sequence detection may be automatic. At energy harvesting levels, there are sub-states to enter depending on whether the stored energy is sufficiently available or unavailable.

[0220] It may be important to calculate the rechargeable battery capacity, i.e., device battery life, for deployment scenarios. Current state-of-the-art rechargeable battery technology depends on the battery's self-discharge characteristics, load characteristics in charging mode, and recharge characteristics. In addition, current state-of-the-art boost DC-DC converter technology may depend on the input voltage range, boost ratio, and output load capability. When designing ultra-low power circuits, it may be important to consider leakage current characteristics. This may involve determining the rechargeable battery capacity requirement (e.g., 100mAh), defining the goal with a single rechargeable POW transmission assuming that POW is received with sufficient strength, i.e., a 1-5% improvement in the current battery state, calculating the size of the capacitor at the DC-DC converter input, and selecting the potential difference required for effective charging, such as calculating the duration of a single POW transmission and the number of transmissions required for different link distances.

[0221] Figure 28 illustrates an exemplary embodiment of a first frame format for energy harvesting. As shown in Figure 28, the ZE preamble 2802 sequence is transmitted, followed by a legacy preamble 2804 which may be decodeable by all 802.11 legacy devices and can be used for synchronization and training. This pair may be followed by the ZE-Sync field 2806 and the ZE-Data field 2808. In one alternative configuration, the legacy preamble 2804 and the ZE preamble 2802 may be interchangeable as they do not affect the expected behavior. In this design, the ZE preamble 2802 may be intended to indicate the presence of a WUR frame and to deliver power when needed.

[0222] This design is another variation of the design described above, where the POW field is moved to the beginning of the frame as a ZE preamble / sequence that can be generated as an energy signature. The power consumption associated with energy signature detection can be ignored compared to the power consumption associated with ZE-Sync / WUR-Sync detection and data decoding. This frame format may be useful in several scenarios.

[0223] In one embodiment, a WUR / ZE-STA with a strong received signal strength may be interested in harvesting energy before attempting to decode the data, but has strict synchronization requirements that necessitate a synchronization sequence (ZE-Sync) immediately before the data field.

[0224] In another embodiment, the WUR / ZE-STA may have an independent environmental energy harvesting circuit and strict synchronization requirements. Therefore, the WUR / ZE-STA does not require indication of the presence of an energy harvesting opportunity, but requires a synchronization sequence (ZE-Sync) immediately preceding the data field.

[0225] In another embodiment, the WUR / ZE-STA may have a weak received signal strength that is not sufficient for energy harvesting but is sufficient for information decoding. The WUR then only needs to detect the ZE-Sync and perform data decoding without attempting to harvest energy.

[0226] A first frame format can be exemplified at a station (STA) by exchanging information with the AP-STA regarding its functions (e.g., battery type, device class, RF front-end structure) and configuration (e.g., mapping to EH window duration based on assigned signatures and supported operating regions). The STA can transition to a passive energy signature detection state and detect the presence of a ZE frame having the first format. Provided that a stored energy level above a first threshold and a received signal intensity above a second threshold are determined based on the current operating region, the STA can transition to a training and synchronization state, and subsequently to an information decoding state. Provided that a unique or group address identifier is detected, the STA can send a wake interrupt to the main transceiver and exchange information with the AP-STA.

[0227] The first and second thresholds may be fixed values, or they may be functions of the received signal strength and energy storage level, respectively. In another alternative, when the first condition is not met, the STA may continue to monitor the channel for energy signatures and / or continue energy harvesting. In an additional alternative, given the second condition that a unique or group address identifier is found, the STA may use backscattering to exchange information with the AP-STA.

[0228] Figure 29 shows a second frame format for energy harvesting. Figure 29 shows a first exemplary embodiment 2910 and a second exemplary embodiment 2930. In the first exemplary embodiment 2910, a ZE preamble 2912 may be transmitted to notify ZE devices of an energy harvesting opportunity. In some embodiments, the transmission may be directed to multiple ZE devices and may be received by ZE devices that are not the target of the transmission (i.e., an untargeted STA intercepts a transmission directed to another STA). A legacy frame 2914 may carry energy to at least some of the ZE devices, and the duration of the energy harvesting opportunity may be indicated in the ZE preamble 2902. This fits well within the existing framework because any access to the medium is based on contention or delay of the IFS period. The first exemplary variant 2910 shows ZE devices performing EH during an EH opportunity from a legacy frame. Once this is complete, the ZE devices participate in data communication. This is an example of simultaneous energy and information transfer.

[0229] In the second embodiment 2930 of the frame format, a dedicated opportunity for transmitting a power-optimized waveform (POW) 2936 may be provided immediately after the preambles 2932 and 2934. Similar to the first frame format, the ZE preamble 2932 and the legacy preamble 2934 may be swapped in position. However, the POW 2936 follows immediately after the preambles 2932 and 2934, as indicated in the preambles 2932 and 2934. Following the POW 2936, the ZE device harvests enough energy to participate in the information transfer indicated in the ZE synchronization 2938 and the data field 2940.

[0230] A second frame format may be exemplified in the STA by exchanging features (e.g., battery type, device class, RF front-end structure) and configuration (e.g., mapping to EH window duration based on assigned signatures and supported operating regions) with the AP-STA. The STA can transition to a signature detection state, detect the presence of a ZE frame having the second format, and determine the current operating region. Provided that the current operating region is determined to be the same as the last reported region, the STA can determine the duration of the energy harvesting (EH) window based on the detected signature and operating region. Provided that the first operating region is determined to be the current region, the STA may utilize a first battery type (battery type 1) to power the training, synchronization, and decoding states. The STA can then transition to the training and synchronization states at the end of the determined EH window duration. The STA can then transition to an information decoding state based on the detection of a known SYNC sequence. Upon detecting a unique or group address identifier, the STA can send a wake interrupt to the main transceiver and exchange information with the AP-STA.

[0231] In another exemplary embodiment, the second frame format may be exemplified in the STA by exchanging the functions (e.g., battery type, device class, RF front-end structure) and configuration (e.g., mapping to EH window duration based on assigned signatures and supported operating regions) with that of the AP-STA. The STA can transition to a signature detection state, detect the presence of a ZE frame having the second format, and determine the current operating region. Provided that the current operating region is determined to be the same as the last reported region, the STA can determine the duration of the EH window based on the detected signature and operating region. Provided that the second operating region is determined to be current, the STA can transition to a dedicated EH state to charge the second battery type (battery type 2) for the determined duration. At the end of the determined EH window duration, the STA can transition to a training and synchronization state and utilize the energy of battery type 2. The STA can transition to an information decoding state based on the detection of a known SYNC sequence and utilize the energy of battery type 2. Upon detecting a unique or group address identifier, the STA can send a wake interrupt to the main transceiver and exchange information with the AP-STA.

[0232] In another exemplary embodiment, a second frame format may be exemplified in the STA by exchanging the functions (e.g., battery type, device class, RF front-end structure) and configuration (e.g., mapping to EH window duration based on assigned signatures and supported operating regions) with that of the AP-STA. The STA can transition to a signature detection state, detect the presence of a ZE frame having the second format, and determine the current operating region. Provided that the current operating region is determined to be the same as the last reported region, the STA can determine the duration of the energy harvesting (EH) window based on the detected signature and operating region. Provided that the third operating region is determined to be current, the STA may transition to a dedicated EH state to charge battery type 2 for part of the determined duration and battery type 1 for the remainder of the determined duration, based on the received signal strength. The STA can transition to a training and synchronization state at the end of the determined EH window duration and utilize the energy of battery type 2. The STA can transition to an information decoding state based on the detection of a known SYNC sequence and utilize the energy of battery type 2. Upon detecting a unique or group address identifier, the STA can send a wake interrupt to the main transceiver and exchange information with the AP-STA.

[0233] The efficiency with which battery storage devices are available in a deployed system depends on the energy harvesting capabilities. Some of these capabilities may be incorporated to utilize opportunistic energy sources, while others are based on dedicated energy harvesting. Opportunistic methods do not interfere with other procedures, such as procedures for data communication. STA uses opportunistic situations to enhance those energy storages.

[0234] In another embodiment, the STA utilizes opportunistic EH opportunities to determine the need for dedicated EH opportunities. Here, the STA may have capabilities (e.g., battery type, device class, RF front-end structure) and configurations (e.g., mapping to EH window duration based on assigned signatures and supported operating areas) that are interchangeable with the AP-STA. The STA can transition to a passive energy signature detection state to detect the presence of an energy harvesting (EH) opportunity. Based on the detected energy signature, or as a pre-configured fixed value, the STA may determine the duration of the EH opportunity. The STA can perform pure EH over the determined duration and transition back to the passive energy signature detection state at the end of that duration. The STA may periodically (or based on configured event detection) report EH quality and / or request a dedicated EH signaling configuration.

[0235] In some cases, energy harvesting can be based on coordination between non-AP STAs in an ad-hoc architecture. In these cases, multiple STAs may be equipped with higher-capacity batteries or may be directly connected to the power grid, and thus able to deliver power to other STAs, illustrating both types of STAs as ZE-STAs.

[0236] In one embodiment, an STA can perform ad hoc energy harvesting by sending a configured preamble to the ZE-STA, in which a measurement opportunity configuration, for example, an energy measurement opportunity (a typical transmission from a nearby STA) follows an expected configured duration. The STA can then receive measurement reports for one or more opportunities, for example, via supported backscatter transmissions. The STA can then determine an STA suitable for energy delivery to the ZE-STA, for example, the STA with the highest measured energy level. After the preamble / energy signature known by the ZE-STA, the STA can send a query request (or a newly defined energy delivery request for a specific duration) to the determined STA. The STA can repeat the query request until an active period for query response transmissions is achieved based on the considered preamble / energy signature.

[0237] With the assistance of hierarchical sequence-based signaling, the STA can exchange functions (e.g., receiver architecture and correlator hierarchy configuration) and additional configurations (such as mapping between identifiers / functions and WuP sequence / energy signatures, and assignment of sets of unique and / or group identifiers) with the AP-STA, as described in the previous section. Based on one or more preambles assigned to the STA, the STA can find the identification information of the associated AP at the first level of the hierarchy, e.g., the preamble corresponding to the BSSID. Note that the AP may also encode hierarchy information at the second level into its signature. In that case, the STA may need to transition to the second level of the correlation hierarchy to find one of the assigned identifiers. Provided that a unique / group identifier is found, the STA may transition to the third level of the correlation hierarchy. This method allows the AP to perform a hierarchical wake-up of the STA, and if a mismatch occurs at one level, the STA can terminate the decoding procedure early.

[0238] The STA detects sequences corresponding to specific operations / functions, such as sensor measurement, main transceiver wake-up, or MAC payload decoding. As detailed earlier, APs and STAs can agree on multiple function-specific wake-up signatures, making hierarchical addressing very useful. Importantly, an STA not addressed by a specific wake-up signature can use transmissions made to other STAs for energy harvesting.

[0239] In exemplary embodiments, the STA can reduce power operating costs via a configurable hierarchical correlation function by exchanging functions (e.g., receiver architecture and correlator hierarchy configuration) and configurations (e.g., mapping between identifiers / functions and WuP sequences / energy signatures, assignment of sets of unique and / or group identifiers) with the AP-STA. At a first level of the hierarchy, the STA may detect the identification information of the associated AP, e.g., a preamble corresponding to the BSSID, and then transition to a second level of the correlation hierarchy to look for one of the assigned identifiers. Provided that a unique / group identifier is found, the STA may transition to a third level of the correlation hierarchy. The STA may detect a sequence corresponding to a specific operation / function, e.g., sensor measurement or main transceiver wake-up or MAC payload decoding. The STA can then perform the detected function or operation.

[0240] In another exemplary embodiment, the STA can receive a wake-up command and postpone the wake-up procedure until a predetermined event and / or opportunistic event. The STA can detect the identity of the sending node from the wake-up sequence. The STA can detect the identity of the sending node as an infrastructure service set from the wake-up sequence. Based on the received wake-up sequence, the STA can detect whether a mobility event has occurred. The STA can make an early decision to decode the wake-up sequence based on hierarchical partial decoding.

[0241] While features and elements are 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. In addition, the methods described herein can be implemented in computer programs, software, or firmware embedded in computer-readable media for execution by a computer or processor. Examples of computer-readable media include electronic signals (transmitted via wired or wireless connections) and computer-readable storage media. Examples of 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 disks and digital versatile disks (DVDs). A processor associated with software can be used to implement a radio frequency transceiver for use in a WTRU, UE, terminal, base station, RNC, or any host computer.

Claims

1. A method performed by a station (STA), During the energy detection state, a zero-energy (ZE) frame indicating the presence of an energy harvesting (EH) window is received from the access point (AP), Harvesting energy over a determined duration within the aforementioned EH window, A method comprising receiving a data portion of a ZE frame based on the fact that the current stored energy of the STA exceeds a first threshold and the signal intensity of the received ZE frame exceeds a second threshold.

2. The method according to claim 1, wherein the EH window is indicated by the ZE preamble.

3. The method according to claim 1, further comprising initiating an uplink access attempt with the AP on the condition that the STA detects a group ID.

4. The method according to claim 1, wherein the duration of the EH window is indicated by a signature.

5. The method according to claim 1, wherein the received ZE frame is a frame targeting another STA.

6. The method according to claim 1, wherein the harvested energy is used to determine whether the STA has enough stored energy to receive the data portion of the ZE frame.

7. The method according to claim 1, wherein the current stored energy is stored in a capacitor.

8. It is a station (STA), Receiver and Transmitter and Includes a processor, The receiver is configured to receive zero-energy (ZE) frames from the access point (AP) indicating the presence of an energy harvesting (EH) window during the energy detection state. The processor is configured to harvest energy over a determined duration within the EH window, The receiver is further configured to receive the data portion of the ZE frame based on the current stored energy of the STA exceeding a first threshold and the signal intensity of the received ZE frame exceeding a second threshold.

9. The STA according to claim 8, wherein the EH window is indicated by the ZE preamble.

10. The STA according to claim 8, wherein the processor is configured to initiate an uplink access attempt with the AP under the condition that the STA detects a group ID.

11. The STA according to claim 8, wherein the duration of the EH window is indicated by a signature.

12. The STA according to claim 8, wherein the received ZE frame is a frame targeting another STA.

13. The harvested energy is used to determine whether the STA has enough stored energy to receive the data portion of the ZE frame, according to claim 8.

14. The STA according to claim 8, wherein the current stored energy is stored in a capacitor.

15. A method performed by a station (STA), During the energy detection state, a zero-energy (ZE) frame indicating the transmission of a power-optimized waveform is received from the access point (AP), Harvesting energy over a duration determined during the transmission of the power-optimized waveform, A method comprising receiving a data portion of a ZE frame based on the fact that the current stored energy of the STA exceeds a first threshold and the signal intensity of the received ZE frame exceeds a second threshold.

16. The method of claim 15, further comprising initiating an uplink access attempt with the AP on the condition that the STA detects a group ID.

17. The method according to claim 15, wherein the received ZE frame is a frame targeting another STA.

18. The method according to claim 15, wherein the harvested energy is used to determine whether the STA has enough stored energy to receive the data portion of the ZE frame.

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