Method and apparatus for adaptive indirect carrier modulation

Abstract

A wireless transmit / receive unit, i.e., WTRU, selects a constellation from a set of constellations corresponding to a symbol configuration of indirect carrier modulation, i.e., ICM, based on at least one constellation performance validity indicator, each constellation performance validity indicator corresponding to a constellation in the set of constellations, and can transmit data while harvesting energy using the selected constellation and symbol configuration.

Description

Background Art

[0001] The indirect carrier modulation method has the potential to realize a transmitter with ultra-low power consumption that can be deployed on a large scale. Existing systems that employ indirect carrier modulation include Near-field communication (NFC) and Radio-frequency identification (RFID).

[0002] In RFID, a so-called reader can interact with multiple devices ( "tags"). The reader supplies RF power and data to the tag in the downlink (DL). The tag uses the RF power supplied by the reader to send back data. The tag modulates the antenna load using a simple method such as On-Off Keying (OOK) and Binary Phase Shift Keying (BPSK) to transmit data and reflects the RF carrier transmitted by the reader back to the reader. Passive RFID devices generally use OOK modulation in the uplink, and OOK modulation is suitable for energy harvesting in the downlink, while semi-passive and active devices employ, for example, BPSK, which is suitable for transmitting high energy per bit in an indirect carrier modulation framework. A specific product supports one frequency band and communication mode. The reader and all tags communicate via the same frequency channel. Therefore, the tag simultaneously performs power reception in the DL and data transmission in the uplink (UL) using the same carrier frequency.

[0003] An RFID system uses indirect carrier modulation transmission between a reader and a tag, which are backscatter coupling devices in the far-field of each other's antennas. An RFID tag can be passive (i.e., without a self-powered source), semi-passive (i.e., having a small battery), or active (i.e., having a self-powered source such as a battery). In existing RFID standards, only one communication mode is defined. This is called the reader / writer mode, and all communication starts when the reader queries the tag. The tag responds only when queried by the reader. In existing RFID standards, several frequency bands ranging from low frequency (125 kHz) to super-high frequency (SHF) (5.8 GHz) are defined. The communication distance of RFID can be extended up to 100 m at most.

[0004] NFC can be said to be an improved version of RFID. NFC is used in various applications such as home automation, household appliances, and smart meters. An NFC system uses indirect carrier modulation transmission between inductively coupled devices, and the reader and the tag are present in the near-field of each other's transducers. An NFC device can be passive, semi-passive, or active. In existing NFC standards, a single frequency band of 13.56 MHz and three communication modes ("reader / writer", "card emulation", and "peer-to-peer") are defined. The communication distance of NFC is approximately from 1 cm to a maximum of 1 m.

Summary of the Invention

[0005] Method and apparatus for operation by a wireless transmit / receive unit (WTRU). The WTRU can select a constellation from a set of constellations corresponding to symbol settings of indirect carrier modulation, i.e., ICM (indirect carrier modulation), based on at least one constellation performance effectiveness metric, each constellation performance effectiveness metric corresponding to a constellation of the set of constellations, and can use the selected constellation and symbol settings to harvest energy and transmit data simultaneously.

Brief Description of the Drawings

[0006] Furthermore, like reference numbers in the figures indicate like elements.

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DETAILED DESCRIPTION OF THE INVENTION

[0007] (Exemplary Network for Implementing the Embodiment) FIG. 1A is a diagram showing an exemplary communication system 100 in which one or more of the disclosed embodiments may be implemented. The communication system 100 can be a plurality of access systems that provide content such as voice, data, video, messaging, and broadcast to a plurality of wireless users. The communication system 100 can enable a plurality of wireless users to access such content through sharing of system resources including wireless bandwidth. For example, the communication system 100 can employ one or more channel access methods such as code division multiple access (CDMA), time division multiple access (TDMA), frequency division multiple access (FDMA), orthogonal FDMA (OFDMA), single-carrier FDMA (SC-FDMA), zero-tail unique-word DFT-Spread OFDM (ZT UW DTS-s OFDM), unique word OFDM (UW-OFDM), resource block filtering OFDM, filter bank multicarrier (FBMC).

[0008] As shown in FIG. 1A, communication system 100 may include wireless transmit / receive units (WTRUs) 102a, 102b, 102c, 102d, a radio access network (RAN) 104, a core network (CN) 106, a public switched telephone network (PSTN) 108, the Internet 110, and other networks 112, but it will be understood that the disclosed embodiments contemplate any number of WTRUs, base stations, networks, and / or network elements. Each of the WTRUs 102a, 102b, 102c, 102d can be any type of device configured to operate and / or communicate in a wireless environment. By way of example, the WTRUs 102a, 102b, 102c, 102d, any of which may be referred to interchangeably as a “station” and / or “STA,” can be configured to transmit and / or receive wireless signals and can be a user equipment (UE), a mobile station, a fixed or mobile subscriber unit, a subscriber-based unit, a pager, a cellular telephone, a personal digital assistant (PDA), a smartphone, a laptop, a netbook, a personal computer, a wireless sensor, a hotspot or Mi-Fi device, an Internet of Things (IoT) device, a watch or other wearable, a head-mounted display (HMD), a vehicle, a drone, a medical device and application (e.g., remote surgery), an industrial device and application (e.g., a robot and / or other wireless device operating in an industrial and / or automated processing chain context), a home appliance device, a device operating in a commercial and / or industrial wireless network, etc. Any of the WTRUs 102a, 102b, 102c, and 102d may be referred to interchangeably as a UE.

[0009] The communication system 100 may also include base station 114a and / or base station 114b. Each of base stations 114a, 114b may be any type of device configured to wirelessly interface with at least one of WTRUs 102a, 102b, 102c, 102d to facilitate access to one or more communication networks such as CN 106, the Internet 110, and / or other network 112. By way of example, base stations 114a, 114b may be a base transceiver station (BTS), Node B, eNodeB, home Node B, home eNodeB, gNB, NR Node B, site controller, access point (AP), wireless router, etc. Although base stations 114a, 114b are each shown as a single element, it will be understood that base stations 114a, 114b may include any number of interconnected base stations and / or network elements.

[0010] Base station 114a may be part of RAN 104 and may also include other base stations and / or network elements (not shown), such as a base station controller (BSC), a radio network controller (RNC), a relay node, etc. Base station 114a and / or base station 114b may be configured to transmit and / or receive radio signals at one or more carrier frequencies, which may be referred to as a cell (not shown). These frequencies may be licensed spectrum, unlicensed spectrum, or a combination of licensed and unlicensed spectrum. The cell may provide wireless service coverage to a specific geographic area that may be relatively fixed or may change over time. The cell may be further divided into cell sectors. For example, the 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 for each sector of the cell. In one embodiment, 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.

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

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

[0013] In one embodiment, the base stations 114a in the RAN 104 and the WTRUs 102a, 102b, 102c can implement radio technologies such as Evolved UMTS Terrestrial Radio Access (E-UTRA), which can establish the air interface 116 using Long-Term Evolution (LTE) and / or LTE-Advanced (LTE-A) and / or LTE-Advanced Pro (LTE-APro).

[0014] In one embodiment, the base stations 114a in the RAN 104 and the WTRUs 102a, 102b, 102c can implement radio technologies such as NR radio access, which can establish the air interface 116 using New Radio (NR).

[0015] In one embodiment, the base stations 114a and the WTRUs 102a, 102b, 102c within RAN 104 may implement multiple radio access technologies. For example, the base stations 114a and the WTRUs 102a, 102b, 102c may implement LTE radio access and NR radio access together, for example, using the dual connectivity (DC) principle. Accordingly, the air interfaces utilized by the WTRUs 102a, 102b, 102c may be characterized by transmissions to / from multiple types of radio access technologies and / or multiple types of base stations (e.g., eNBs and gNBs).

[0016] In other embodiments, the base stations 114a and the WTRUs 102a, 102b, 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, Interim Standard 2000 (IS-2000), Interim Standard 95 (IS-95), Interim Standard 856 (IS-856), Global System for Mobile communications (GSM), GSM Evolution (Enhanced Data rates for GSM Evolution (EDGE)), GSM EDGE (GERAN), etc.

[0017] The base station 114b in FIG. 1A may be, for example, a wireless router, a home node B, a home eNode B, or an access point, and may utilize any suitable RAT to facilitate wireless connection in a local area such as an office, a home, a vehicle, a campus, an industrial facility, an aerial corridor (e.g., for use by a drone), a road, or other locations. In one embodiment, the base station 114b and the WTRUs 102c, 102d may implement a wireless technology such as IEEE 802.11 to establish a wireless local area network (WLAN). In one embodiment, the base station 114b and the WTRUs 102c, 102d may implement a wireless technology such as IEEE 802.15 to establish a wireless personal area network (WPAN). In yet another embodiment, the base station 114b and the WTRUs 102c, 102d may utilize a cellular-based RAT (e.g., WCDMA, CDMA2000, GSM, LTE, LTE-A, LTE-A Pro, NR, etc.) to establish a pico cell or a femto cell. As shown in FIG. 1A, the base station 114b may have a direct connection to the Internet 110. Thus, the base station 114b may not need to access the Internet 110 via the CN 106 in some cases.

[0018] RAN 104 may communicate with CN 106, 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 WTRUs 102a, 102b, 102c, 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, mobility requirements, etc. CN 106 may provide call control, billing services, mobile location-based services, prepaid calls, internet connectivity, video distribution, etc., and / or may perform high-level security functions such as user authentication. Although not shown in FIG. 1A, it will be understood that RAN 104 and / or CN 106 may communicate directly or indirectly with other RANs using the same RAT or a different RAT as RAN 104. For example, in addition to being connected to RAN 104, which may utilize NR radio technology, CN 106 may also communicate with another RAN (not shown) using GSM, UMTS, CDMA2000, WiMAX, E-UTRA, or WiFi radio technology.

[0019] CN106 may also function as a gateway for WTRU102a, 102b, 102c, 102d to access the PSTN108, the Internet 110, and / or other networks 112. The PSTN108 may include a public switched telephone network that provides plain old telephone service (POTS). The Internet 110 may include a global system of interconnected computer networks and devices that use common communication protocols such as the transmission control protocol (TCP), the user datagram protocol (UDP), and / or the Internet protocol (IP) of the TCP / IP Internet protocol suite. Other networks 112 may include wired and / or wireless communication networks owned and / or operated by other service providers. For example, other networks 112 may include another CN connected to one or more RANs that may use the same or a different RAT as the RAN 104.

[0020] Some or all of the WTRU102a, 102b, 102c, 102d in the communication system 100 may include multimode capabilities (e.g., the WTRU102a, 102b, 102c, 102d may include multiple transceivers for communicating with different wireless networks via different wireless links). For example, the WTRU102c shown in FIG. 1A may be configured to communicate with a base station 114a that can use cellular-based wireless technology and a base station 114b that can use IEEE802 wireless technology.

[0021] Figure 1B is a system diagram illustrating an exemplary WTRU102. As shown in Figure 1B, the WTRU102 can 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, a non-removable memory 130, a removable memory 132, a power source 134, a chipset 136 of a positioning system such as a Global Positioning System (GPS), and / or other elements 138. It will be understood that the WTRU102 can include any partial combination of the foregoing elements while remaining consistent with one embodiment.

[0022] The processor 118 can be a general-purpose processor, a dedicated processor, a conventional processor, a digital signal processor (DSP), a plurality of microprocessors, one or more microprocessors associated with a DSP core, a controller, a microcontroller, an application specific integrated circuit (ASIC), a field programmable gate array (FPGA) circuit, any other type of integrated circuit (IC), a state machine, etc. The processor 118 can perform signal coding, data processing, power control, input / output processing, and / or any other function that enables the WTRU102 to operate in a wireless environment. The processor 118 can be coupled to a transceiver 120 that can be coupled to a transmit / receive element 122. Although Figure 1B shows the processor 118 and the transceiver 120 as separate components, it will be understood that the processor 118 and the transceiver 120 can be integrated together in an electronic package or chip.

[0023] The transmit / receive element 122 may be configured to transmit signals to or receive signals from a base station (e.g., base station 114a of FIG. 1A) 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 wireless signals.

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

[0025] The transceiver 120 may be configured to modulate signals transmitted by the transmit / receive element 122 and demodulate signals received by the transmit / receive element 122. As described above, the WTRU 102 may have multi-mode capabilities. Thus, the transceiver 120 may include multiple transceivers to enable the WTRU 102 to communicate via multiple RATs such as, for example, NR and IEEE 802.11.

[0026] The processor 118 of the WTRU 102 can be coupled to the speaker / microphone 124, keypad 126, and / or display / touchpad 128 (e.g., a liquid crystal display (LCD) display unit or an organic light-emitting diode (OLED) display unit) and can receive user input data therefrom. The processor 118 can also output user data to the speaker / microphone 124 and / or the display / touchpad 128. Further, the processor 118 can access information from and store data in any suitable type of memory, such as the non-removable memory 130 and / or the removable memory 132. The non-removable memory 130 can include random-access memory (RAM), read-only memory (ROM), a hard disk, or any other type of memory storage device. The removable memory 132 can 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 can access information from and store data in a memory that is not physically located on the WTRU 102, such as on a server or a home computer (not shown).

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

[0028] The processor 118 may also be coupled to a GPS chipset 136, which may be configured to provide location information (e.g., longitude and latitude) regarding the current location of the WTRU 102. In addition to or instead of information from the GPS chipset 136, the WTRU 102 may receive location information from a base station (e.g., base stations 114a, 114b) via the air interface 116 and / or may 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 obtain location information by any suitable positioning method while remaining consistent with one embodiment.

[0029] The processor 118 may further be coupled to other elements 138, which may include one or more software modules and / or hardware modules that provide additional features, functionality, and / or wired or wireless connectivity. For example, the elements 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, etc. The elements 138 may include one or more sensors, and the sensors may be one or more of a gyroscope, an accelerometer, a Hall effect sensor, a magnetometer, an orientation sensor, a proximity sensor, a temperature sensor, a time sensor, a geolocation sensor, an altimeter, a light sensor, a touch sensor, a magnetometer, a barometer, a gesture sensor, a biometric sensor, and / or a humidity sensor.

[0030] The WTRU 102 may include a full-duplex radio in which some or all of the transmission and reception of signals (e.g., associated with specific subframes for both UL (e.g., for transmission) and downlink (e.g., for reception)) can be parallel and / or simultaneous. The full-duplex radio may include an interference management unit for reducing and / or substantially eliminating self-interference via hardware (e.g., choke) or signal processing via a processor (e.g., via a separate processor (not shown) or the processor 118). In one embodiment, the WRTU 102 may include a half-duplex radio for the transmission and reception of any of some or all of the signals (e.g., associated with specific subframes for either UL (e.g., for transmission) or downlink (e.g., for reception)).

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

[0032] The RAN 104 may include eNode-Bs 160a, 160b, 160c, although it will be understood that the RAN 104 may include any number of eNode-Bs while remaining consistent with one embodiment. Each of the eNode-Bs 160a, 160b, 160c may include one or more transceivers for communicating with the WTRUs 102a, 102b, 102c via the air interface 116. In one embodiment, the eNode-Bs 160a, 160b, 160c may implement MIMO technology. Thus, the eNode-B 160a, for example, can transmit a radio signal to and / or receive a radio signal from the WTRU 102a using a plurality of antennas.

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

[0034] CN 106 shown in Figure 1C may include a mobility management entity (MME) 162, a serving gateway (SGW) 164, and a packet data network (PDN) gateway (or PGW) 166. Although each of the foregoing elements is depicted as part of CN 106, it will be understood that any of these elements may be owned and / or operated by an entity other than the CN operator.

[0035] MME 162 can be connected to each of eNode-Bs 162a, 162b, and 162c in RAN 104 via the S1 interface and can function as a control node. For example, MME 162 can authenticate WTRUs 102a, 102b, 102c, users with bearer activation / deactivation, and can play a role in selecting a specific serving gateway during the initial attachment of WTRUs 102a, 102b, 102c. MME 162 can provide control plane functions for switching between RAN 104 and other RANs (not shown) that employ other radio technologies such as GSM and / or WCDMA.

[0036] SGW 164 can be connected to each of eNode Bs 160a, 160b, and 160c in RAN 104 via the S1 interface. SGW 164 can generally route and transfer user data packets to / from WTRUs 102a, 102b, and 102c. SGW 164 can perform other functions such as the function of anchoring the user plane during handover between eNode Bs, the function of triggering paging when DL data is available to WTRUs 102a, 102b, and 102c, and the function of managing and storing the contexts of WTRUs 102a, 102b, and 102c.

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

[0038] CN 106 can facilitate communication with other networks. For example, CN 106 can provide WTRUs 102a, 102b, and 102c with access to a circuit switched network such as PSTN 108 to facilitate communication between WTRUs 102a, 102b, and 102c and conventional landline communication devices. For example, CN 106 can include or communicate with an IP gateway (e.g., an IP Multimedia Subsystem (IMS) server) that functions as an interface between CN 106 and PSTN 108. Further, CN 106 can provide WTRUs 102a, 102b, and 102c with access to other networks 112 that can include other wired and / or wireless networks owned and / or operated by other service providers.

[0039] The WTRU is described as a wireless terminal in FIGS. 1A - 1D, but in certain representative embodiments, it is contemplated that such a terminal can use a wired communication interface (e.g., temporarily or permanently) with a communication network.

[0040] In an exemplary embodiment, the other network 112 can be a WLAN.

[0041] A WLAN in infrastructure basic service set (BSS) mode can have an access point (AP) of the BSS and one or more stations (STAs) associated with the AP. The AP can have access to or an interface to a distribution system (DS) or another type of wired / wireless network that conveys traffic within and / or outside the BSS. Traffic to an STA originating from outside the BSS can reach and be delivered to the STA through the AP. Traffic originating from an STA to a destination outside the BSS can be sent to the AP and then sent to the respective destination. Traffic between STAs within the BSS can be sent, for example, via the AP, where the source STA can send the traffic to the AP and the AP can deliver the traffic to the destination STA. Traffic between STAs within the BSS can be considered and / or referred to as peer-to-peer traffic. Peer-to-peer traffic can be sent in a direct link setup (DLS) between the source STA and the destination STA (e.g., directly between them). In certain exemplary embodiments, the DLS can use 802.11e DLS or 802.11z tunneled DLS (TDLS). A WLAN using independent BSS (IBSS) mode may not have an AP, and STAs within or using the IBSS (e.g., all of the STAs) can communicate directly with each other. The IBSS mode of communication can be referred to herein as the "ad hoc" communication mode.

[0042] When using the 802.11ac infrastructure operation mode or a similar operation mode, the 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 width dynamically set via signaling. 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 some representative embodiments, for example, in an 802.11 system, Carrier Sense Multiple Access / Collision Avoidance (CSMA / CA) with collision avoidance may be implemented. In the case of CSMA / CA, STAs including the AP (e.g., all STAs) may sense the primary channel. If the primary channel is sensed / detected as busy by a particular STA and / or determined to be so, the particular STA may back off. Only one STA (e.g., only one station) may transmit at any given time in a given BSS.

[0043] A High Throughput (HT) STA may form a 40 MHz wide channel for communication, for example, via a combination of the primary 20 MHz channel and adjacent or non - adjacent 20 MHz channels.

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

[0045] The sub-1 GHz operating mode is supported by 802.11af and 802.11ah. The channel operating bandwidth and carriers are reduced in 802.11af and 802.11ah compared to those used in 802.11n and 802.11ac. 802.11af supports 5 MHz, 10 MHz, and 20 MHz bandwidths in the TV White Space (TVWS) spectrum, and 802.11ah supports 1 MHz, 2 MHz, 4 MHz, 8 MHz, and 16 MHz bandwidths using the non-TVWS spectrum. According to an exemplary embodiment, 802.11ah may support meter type control / machine-type communications (MTC), such as MTC devices in a macro coverage area. The MTC device may have limited capabilities, including support for a particular and / or limited bandwidth (e.g., support only therefor). The MTC device may include a battery having a battery life exceeding a threshold (e.g., to maintain a very long battery life).

[0046] A WLAN system that supports multiple channels and channel bandwidths such as 802.11n, 802.11ac, 802.11af, and 802.11ah includes channels that can be designated as primary channels. The primary channel may have a bandwidth equal to the maximum common operating bandwidth supported by all STAs in the BSS. The bandwidth of the primary channel can be set and / or restricted by an STA from among all STAs operating in a BSS that supports the minimum bandwidth operation mode. In the example of 802.11ah, the primary channel is 1 MHz wide for an STA (e.g., an MTC type device) that supports the 1 MHz mode (e.g., supports only that) even when the AP and other STAs in the BSS support 2 MHz, 4 MHz, 8 MHz, 16 MHz, and / or other channel bandwidth operation modes. Carrier sensing and / or Network Allocation Vector (NAV) setting may depend on the state of the primary channel. For example, if the primary channel is busy due to an STA transmitting to the AP (supporting only the 1 MHz operation mode), the entire available frequency band may be considered busy even if most of the frequency band remains idle and available.

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

[0048] FIG. 1D is a system diagram illustrating RAN 113 and CN 115 according to one embodiment. As described above, RAN 113 can communicate with WTRUs 102a, 102b, 102c via air interface 116 using NR radio technology. RAN 113 can also communicate with CN 115.

[0049] RAN 113 may include gNBs 180a, 180b, and 180c, but it will be understood that RAN 113 may include any number of gNBs while remaining consistent with one embodiment. Each of gNBs 180a, 180b, and 180c may include one or more transceivers for communicating with WTRUs 102a, 102b, and 102c via air interface 116. In one embodiment, gNBs 180a, 180b, and 180c may implement MIMO technology. For example, gNBs 180a, 180b, and 180c may use beamforming to transmit and / or receive signals to / from WTRUs 102a, 102b, and 102c. Thus, gNB 180a, for example, may transmit a wireless signal to WTRU 102a and / or receive a wireless signal from WTRU 102a using multiple antennas. In one embodiment, gNBs 180a, 180b, and 180c may implement carrier aggregation technology. For example, gNB 180a may be able to transmit multiple component carriers (not shown) to WTRU 102a. A subset of these component carriers may be on unlicensed spectrum and the remaining component carriers may be on licensed spectrum. In one embodiment, gNBs 180a, 180b, and 180c may implement coordinated multi-point (CoMP) technology. For example, WTRU 102a may be able to receive coordinated transmissions from gNB 180a and gNB 180b (and / or gNB 180c).

[0050] WTRU102a, 102b, and 102c can communicate with gNB180a, 180b, and 180c using transmissions associated with an extensible numerology. For example, the OFDM symbol interval and / or the OFDM sub-carrier interval can vary for different transmissions, different cells, and / or different portions of the radio transmission spectrum. WTRU102a, 102b, and 102c can communicate with gNB180a, 180b, and 180c using sub-frames or transmission time intervals (TTIs) of various or scalable lengths (e.g., including various numbers of OFDM symbols and / or having absolute times of various lengths).

[0051] gNBs 180a, 180b, and 180c can be configured to communicate with WTRUs 102a, 102b, and 102c in a stand-alone configuration and / or a non-stand-alone configuration. In a stand-alone configuration, WTRUs 102a, 102b, and 102c can communicate with gNBs 180a, 180b, and 180c without accessing other RANs (e.g., eNode-Bs 160a, 160b, and 160c in FIG. 1C, etc.). In a stand-alone configuration, WTRUs 102a, 102b, and 102c can utilize one or more of gNBs 180a, 180b, and 180c as mobility anchor points. In a stand-alone configuration, WTRUs 102a, 102b, and 102c can communicate with gNBs 180a, 180b, and 180c using signals in an unlicensed band. In a non-stand-alone configuration, WTRUs 102a, 102b, and 102c can communicate with and connect to gNBs 180a, 180b, and 180c while also communicating with and connecting to another RAN such as eNode-Bs 160a, 160b, and 160c. For example, WTRUs 102a, 102b, and 102c can implement a DC principle for communicating with one or more gNBs 180a, 180b, and 180c and one or more eNode-Bs 160a, 160b, and 160c substantially simultaneously. In a non-stand-alone configuration, eNode-Bs 160a, 160b, and 160c can function as the mobility anchor for WTRUs 102a, 102b, and 102c, and gNBs 180a, 180b, and 180c can provide additional coverage and / or throughput for serving WTRUs 102a, 102b, and 102c.

[0052] Each of gNBs 180a, 180b, and 180c can be associated with a specific cell (not shown) and can be configured to handle radio resource management decisions, handover decisions, user scheduling in UL and / or DL, support for network slicing, dual connectivity, interworking between NR and E-UTRA, routing of user plane data to user plane functions (UPFs) 184a, 184b, routing of control plane information to access and mobility management functions (AMFs) 182a, 182b, etc. As shown in FIG. 1D, gNBs 180a, 180b, and 180c can communicate with each other via the Xn interface.

[0053] CN 115 shown in FIG. 1D can include at least one AMF 182a, 182b, at least one UPF 184a, 184b, at least one session management function (SMF) 183a, 183b, and optionally data networks (DNs) 185a, 185b. Although each of the foregoing elements is depicted as part of CN 115, it will be understood that any of these elements can be owned and / or operated by entities other than the CN operator.

[0054] AMF 182a and 182b can be connected to one or more of gNBs 180a, 180b, and 180c in RAN 113 via the N2 interface and can function as control nodes. For example, AMF 182a and 182b can perform functions such as user authentication of WTRUs 102a, 102b, and 102c, support for network slicing (e.g., handling of different protocol data unit (PDU) sessions with different requirements), selection of specific SMFs 183a and 183b, registration area management, termination of NAS signaling, and mobility management. Network slices can be used by AMF 182a and 182b to customize the CN support for WTRUs 102a, 102b, and 102c based on the type of service being utilized by WTRUs 102a, 102b, and 102c. For example, different network slices can 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. AMF 162 can provide control plane functions for switching between RAN 113 and other RANs (not shown) that employ other radio technologies such as non-3GPP access technologies like LTE, LTE-A, LTE-A Pro, and / or WiFi.

[0055] SMF183a and 183b can be connected to AMF182a and 182b in CN115 via the N11 interface. SMF183a and 183b can also be connected to UPF184a and 184b in CN115 via the N4 interface. SMF183a and 183b can select and control UPF184a and 184b and configure the routing of traffic passing through UPF184a and 184b. SMF183a and 183b can perform other functions such as managing and allocating UE IP addresses, managing PDU sessions, controlling policy enforcement and QoS, and providing downlink data notifications. The PDU session type can be IP-based, non-IP-based, Ethernet-based, etc.

[0056] UPF184a and 184b can be connected to one or more of gNB180a, 180b, and 180c in RAN113 via the N3 interface, which can provide access to a packet-switched network such as the Internet 110 to WTRU102a, 102b, and 102c to facilitate communication between WTRU102a, 102b, and 102c and IP-compatible devices. UPF184 and 184b can perform other functions such as routing and forwarding packets, enforcing user plane policies, supporting multi-home PDU sessions, handling user plane QoS, buffering downlink packets, and providing mobility anchoring.

[0057] CN115 may facilitate communication with other networks. For example, CN115 may include or communicate with an IP gateway (e.g., an IP Multimedia Subsystem (IMS) server) that functions as an interface between CN115 and PSTN108. Further, CN115 may provide access to other network 112, which may include other wired and / or wireless networks owned and / or operated by other service providers, to WTRU102a, 102b, 102c. In one embodiment, WTRU102a, 102b, 102c may be connected to local Data Network (DN) 185a, 185b through UPF184a, 184b via an N3 interface to UPF184a, 184b and an N6 interface between UPF184a, 184b and DN185a, 185b.

[0058] Looking at FIGS. 1A - 1D and the corresponding descriptions of FIGS. 1A - 1D, one or more of the functions described herein related to one or more of 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 device described herein may be implemented by one or more emulation devices (not shown). An emulation device may be one or more devices configured to emulate one or more or all of the functions described herein. For example, an emulation device may be used to test other devices and / or simulate network and / or WTRU functionality.

[0059] An emulation device can be designed to implement one or more tests of other devices in a laboratory environment and / or an operator network environment. For example, one or more emulation devices can be fully or partially implemented and / or deployed as part of a wired and / or wireless communication network to test other devices within the communication network and, while being deployed, can execute one or more or all functions. One or more emulation devices can execute one or more or all functions while being temporarily implemented / deployed as part of a wired and / or wireless communication network. An emulation device can be directly coupled to another device for testing purposes and / or can execute tests using terrestrial wireless communication.

[0060] One or more emulation devices can execute one or more functions, including all, while not being implemented / deployed as part of a wired and / or wireless communication network. For example, an emulation device can be utilized in a test scenario in a test laboratory and / or in a wired and / or wireless communication network that is not deployed (e.g., for testing) to implement tests of one or more components. One or more emulation devices can be test equipment. Direct RF coupling and / or wireless communication via an RF circuit (which can include one or more antennas) can be used by an emulation device to transmit and / or receive data.

[0061] (Detailed description) An important challenge for future cellular communications is the need to support many billions of connected, highly mobile devices. The data transfer speed of mobile phones has increased dramatically over the past 30 years (nearly six orders of magnitude), while the improvement in battery energy density has been less than a factor of 10 from 1990 to 2015. This is a major challenge for scaling to one billion devices. As an example, if one billion devices are deployed and each has a 10-year battery life, it is estimated that an average of 274 million batteries would need to be replaced per day. In addition, there are cases where battery replacement is difficult, if not impossible. Therefore, rethinking the radio transceiver, air interface, and overall system may be effective for scaling to one billion devices.

[0062] Important advancements that are thought to support this scaling include ultra-low power RF transmitters that can support link budgets, at least for small cells, zero-energy uplink air interfaces that are powered from the device's battery to enable "permanent" batteries in the short term and battery-less operation of the device in the long term, and scalable system frameworks that can support diverse deployment scenarios and device types.

[0063] For example, an indirect carrier modulation-based backscatter coupling communication framework used in a long-distance RFID system may be useful when integrating a large number of mobile connected devices into a mobile communication network (e.g., future 3GPP and IEEE networks). For this purpose, an ultra-low power transponder for terminal devices that enables a communication distance of several tens to several hundreds of meters is considered useful. These transponders are considered to support multiple operating modes and dynamically adapt to different operating environments. Such devices are considered to benefit from more advanced coding and modulation schemes while being limited in power consumption and cost (compared to, for example, the currently specified schemes for RFID systems). Furthermore, these devices are considered to benefit even when wirelessly powered from the network.

[0064] Somewhat simplified transponders that use indirect carrier modulation can include an antenna, a programmable antenna load, and an indirect carrier modulator (ICM) with a load modulator, a memory module for storing the payload, an energy harvester, and (optionally) a battery with a level indicator. Data is transmitted on the UL by reflecting the incident wave according to the payload. The antenna load of the ICM can be set to different impedance states, and the antenna load modulator can dynamically set the antenna load according to the specified modulation type and payload.

[0065] The antenna load determines both the transmitted energy and the harvested energy. Let the power of the incident RF signal be P IN and when the antenna load is set to the power reflection coefficient Г, the harvested power is (1 - Г)P IN λ, where λ < 1 is the power conversion efficiency of the energy harvester. The energy transmitted or reflected is ГP IN is.

[0066] In currently deployed indirect carrier modulation transmission systems (e.g., inductively coupled NFC and backscatter coupled RFID), there is a fixed trade-off between UL throughput and reliability and DL energy harvesting efficiency. Each specified device class is optimized for either DL energy harvesting efficiency (i.e., battery-less passive class devices) or UL throughput and reliability (i.e., semi-passive class devices with on-board batteries). Existing products are designed to support only a single operation class, and all classes support relatively low data rates.

[0067] Inductively coupled indirect carrier modulation transmission In an inductively coupled indirect carrier modulation transmission system (e.g., NFC), there is an inherent trade-off between communication range and throughput. Reducing the data symbol duration to improve UL throughput results in a shorter communication range.

[0068] As the coupling quality factor between the reader and the transponder increases, the link bandwidth becomes narrower. This limits the minimum achievable duration of UL data symbols and thus the maximum UL throughput, but improves DL power transfer efficiency. Reducing the coupling quality factor to widen the link bandwidth, enable shorter symbol durations, and support higher UL throughput results in a decrease in DL power transfer efficiency. In this case, to support full passive operation or semi-passive operation, the reader and the transponder must be brought closer to each other.

[0069] This trade-off between UL communication range and throughput can be mitigated by using higher order modulation (e.g., QPSK, 16-QAM). However, in a transmission system employing indirect carrier modulation, enabling higher order modulation using conventional methods poses a trade-off between throughput and transponder complexity.

[0070] In the currently proposed approach, points are mapped from the UL constellation to the individual reflection states of the antenna load modulator. This means that, for example, 16 different reflection states are required to support 16-QAM. Since the number of reflection states increases with the modulation order, the complexity of the antenna load modulator can become impractical, especially in passive and semi-passive transponders that support high-order modulation (e.g., 64-QAM). The complexity of passive and semi-passive transponders needs to be noted because it directly affects the cost of the transponder.

[0071] Backscatter-coupled indirect carrier modulation transmission In a backscatter-coupled indirect carrier modulation system, there is an inherent trade-off between the reflected power in the UL and the harvested power in the DL. The UL performance is linked to the DL via the energy harvesting function of a backscatter system (e.g., RFID) that exchanges data in the UL while supplying power in the DL.

[0072] The selection of the UL constellation (the number and spacing of constellation points) affects both UL performance (e.g., throughput, BER) and DL power harvesting efficiency. Widening the spacing between constellation points improves the UL signal-to-noise ratio and thus the BER, but decreases the DL power harvesting efficiency. Using high-order modulation to improve UL throughput and spectral efficiency for a specified minimum BER performance also decreases the DL power harvesting efficiency.

[0073] For example, many of the new ultra-low power use cases envisioned for 5G NR are expected to employ backscatter-coupled indirect carrier modulation transmission in the terminal device. These devices must support multiple operating modes in order to provide, as needed, improved data rate and link reliability, or long battery life. Such terminal devices can benefit from improved coding modulation schemes and constellation adaptation procedures for inductive coupling and backscatter-coupled indirect carrier modulation transmission systems.

[0074] Constellation adaptation In an indirect carrier modulation (ICM) transmission system, the UL performance is linked to the DL via an energy harvesting function. For example, a backscatter transponder (e.g., RFID) transmits data in the UL while harvesting energy in the DL using the same RF carrier. Two commonly used primary indirect carrier modulation schemes and the associated two-point constellations are shown in FIGS. 2A and 2B, respectively. The constellation of FIG. 2A utilizes on-off keying (OOK) with the zero reflection (100% absorption) state S0 of the ICM as a point of the constellation and the zero absorption (100% reflection) state S1, and the constellation of FIG. 2B utilizes binary phase shift keying (BPSK) with two zero absorption (100% reflection) states S1, S2. The DL energy harvesting efficiency of the approach of FIG. 2B is 0%, but it transmits higher energy per symbol in the UL compared to the approach of FIG. 2A. On the other hand, the approach of FIG. 2A has good DL energy harvesting efficiency but transmits lower energy per symbol in the UL.

[0075] Figures 3A and 3B respectively show two examples of the secondary indirect carrier modulation method and the related 4-point constellation. The constellation in Figure 3A utilizes Quadrature Phase-Shift Keying (QPSK) with four states S1 to S4, and the constellation in Figure 3B utilizes four-point Quadrature Amplitude Modulation (4-QAM) with the zero reflection (100% absorption) state S0 of ICM as a point of the constellation. When the vector distance r of the return loss circle between constellation points is kept constant, the method in Figure 3A transmits higher energy per bit and can ensure a relatively large minimum distance between constellation points. On the other hand, the method in Figure 3B can provide better DL energy harvesting efficiency, but the minimum distance between constellation points is relatively small.

[0076] In one embodiment of this principle, the WTRU can use an adaptive method that can select the arrangement of constellation points for a given modulation order.

[0077] In such an adaptive method, the WTRU can adapt the signal constellation for a specified uplink modulation order. The UE can meet the DL power reception requirement by utilizing the zero reflection state of ICM (i.e., transmit muting) as a point of the UL signal constellation. The UE can enhance the UL reliability by increasing the radius of the return loss circle including the ICM reflection state representing the points of the UL signal constellation. Also, the WTRU performs the adaptation of the signal constellation based on the composite requirements of energy harvesting and the payload reliability requirement of UL transmission, and further can select the uplink signal constellation arrangement based on at least one of, for example, the current battery level indicator, the downlink power reception efficiency, and the uplink payload reliability.

[0078] The trade-off between energy harvesting and UL reliability can be achieved by determining the placement of constellation points for a corresponding modulation order (i.e., a specific number of constellation points). The device can perform automatic constellation adaptation triggered, for example, by a data retransmission request from the network, as described below.

[0079] Figure 14 shows an example of a possible transmission method 1400 according to an embodiment of the present principle. In this example, a network 1402 communicates with a WTRU 1404.

[0080] In step S1401, the network sends a non-modulated (CW) transmission to the WTRU, and the WTRU reflects to the network a capability report including a list of supported constellation arrangements for each supported modulation order.

[0081] In step S1403, the network sends a modulated transmission to the WTRU including a WTRU configuration having priorities for at least a part of the list of supported constellation arrangements.

[0082] In step S1405, the network sends a non-modulated (CW) transmission to the WTRU, and the WTRU uses the highest-priority constellation arrangement for that modulation order when reflecting the data.

[0083] In step S1407, the network sends a modulated transmission to the WTRU including a first retransmission request.

[0084] In step S1409, the network sends a non-modulated (CW) transmission to the WTRU, and the WTRU uses the next (i.e., second)-highest-priority constellation arrangement for that modulation order when reflecting the retransmitted data.

[0085] In step S1411, the network transmits a modulated transmission including a second retransmission request to the WTRU.

[0086] In step S1413, the network transmits an unmodulated (CW) transmission to the WTRU, and the WTRU uses the next (i.e., third) highest priority constellation arrangement for that modulation order when reflecting the retransmitted data.

[0087] In one embodiment, the device can report a list of supported constellation arrangements for each supported modulation order using a pre-specified or pre-configured modulation type and modulation order having a pre-specified or pre-configured arrangement of constellation points. As an example, the device can report a list of supported constellation arrangements for each supported modulation using the standard constellation of OOK modulation shown in FIG. 2A. As an additional example, a list of constellation arrangements supported by the device for secondary modulation, including the standard constellation of QPSK, is shown in FIG. 3A, and a second constellation utilizing the zero reflection state (S0) is shown in FIG. 3B.

[0088] In another embodiment, the device receives a setting that includes a priority or ranking for a reported constellation arrangement for each reported modulation order. For example, the default constellation type (e.g., highest priority) for a battery-less passive device can be the constellation type that provides the highest DL energy harvesting efficiency supported. An example of the default constellation type for secondary modulation is the constellation that utilizes the zero reflection state (S0) shown in FIG. 3B. For example, the lowest priority constellation for a battery-less passive device can be the constellation that provides the highest UL transmission energy per bit at a given modulation order. An example of the lowest priority constellation type for secondary modulation is the standard constellation of QPSK shown in FIG. 3A.

[0089] In one embodiment, a device that transmits data uses the highest priority constellation arrangement that provides the highest DL energy harvesting efficiency supported.

[0090] In one embodiment, the device receives a data retransmission request from the network or fails to receive an ACK within a pre-specified time window for a pre-specified number of consecutive times that are specified, signaled, or pre-configured.

[0091] In one embodiment, when the device receives a data retransmission request from the network, it switches to the next configured constellation and modulation type on the priority list and retransmits the data.

[0092] In one embodiment, the device continues data transmission using the selected constellation and modulation type unless it receives an additional data retransmission request from the network. Otherwise, the device selects the next configured constellation and modulation type on the priority list and retransmits the data. The device can repeat this process until it has exhausted the constellations on the priority list or until it reaches a signaling or pre-configured total number of retransmissions, at which point the device can declare a data transmission / connection failure.

[0093] Next, a network assistance procedure in which the WTRU has full control over which constellation arrangement to use for a given modulation order will be described in the following embodiments. In this case, it is assumed that the network can blindly detect which transmission settings were utilized by the WTRU for data transmission.

[0094] FIG. 15 shows an example of a possible transmission method 1500 according to one embodiment of the present principle. In this example, a network 1502 communicates with a WTRU 1504.

[0095] In step S1501, the network sends unmodulated (CW) transmission to the WTRU, and the WTRU reflects back to the network a capability report that includes, for example, a list of supported constellation arrangements for each supported modulation order.

[0096] In step S1503, the network sends modulation transmission to the WTRU that includes a Channel - Quality Indicator (CQI) mapping that includes a mapping between the CQI value and the supported constellation arrangements within the reported list.

[0097] In step S1505, the network sends a modulated transmission to the WTRU that includes a CQI measurement assistance setting including a unique ID and a unique ID transmission opportunity (e.g., timing and frequency settings). The unique ID is used for transmission by the device, enabling the network to identify the transmitting device and measure the channel quality associated with the transmitting device.

[0098] In step S1507, the network sends an unmodulated (CW) transmission to the WTRU, and the WTRU reflects the unique ID transmission to the network.

[0099] In step S1509, the network sends a modulated transmission to the WTRU that includes a CQI measurement report.

[0100] In step S1511, the WTRU selects a constellation configuration based on the CQI value reported by the network and the configured CQI mapping.

[0101] In step S1513, the network sends an unmodulated (CW) transmission to the WTRU, and the WTRU reflects data to the network using the selected constellation configuration.

[0102] In one embodiment, the WTRU reports a list of supported constellation configurations for each supported modulation order using a pre-specified or pre-configured modulation type and modulation order having a pre-specified or pre-configured arrangement of constellation points. As an example, the WTRU can report a list of supported constellation configurations for each supported modulation using the standard constellation of OOK modulation shown in FIG. 2A. As an additional example, a list of constellation configurations supported by the WTRU for, e.g., secondary modulation, includes the standard constellation of QPSK shown in FIG. 3A and a second constellation using the zero reflection state (S0) shown in FIG. 3B.

[0103] In one embodiment, the WTRU receives a mapping between a Channel Quality Indicator (CQI) value and a list of reported constellation arrangements for each reported modulation order.

[0104] In one embodiment, the WTRU receives CQI measurement assistance settings, such as a unique ID, the period of the unique ID transmitter opportunity.

[0105] In one embodiment, the WTRU uses the signaling modulation type / modulation order and constellation / symbol settings to periodically transmit the set unique ID to facilitate CQI measurement by the network.

[0106] In one embodiment, the WTRU periodically, or Q i is related

[0107] [Number] (where f() is a function of the most recent N measurement values) under the condition that it satisfies, a CQI measurement report including the current measured CQI value (Q i ) is received from the network.

[0108] In one embodiment, the WTRU selects a constellation arrangement from a pre-set list based on the CQI value reported by the network and a pre-set mapping.

[0109] In one embodiment, the WTRU continues data transmission using the selected new constellation arrangement and modulation order.

[0110] In the following embodiments, a fully autonomous procedure for the WTRU to perform constellation adaptation based on the evaluation of performance metrics will be described.

[0111] Figure 16 shows an example of a possible transmission method 1600 according to an embodiment of the present principle. In this example, it is assumed that the network 1602 communicates with the WTRU 1604 and that the network can blindly detect which transmission settings were used for data transmission by the WTRU.

[0112] In step S1601, the network sends unmodulated (CW) transmission to the WTRU, and the WTRU reflects to the network a capability report that includes, for example, a list of supported constellation arrangements for each supported modulation order.

[0113] In step S1603, the network sends modulated transmission to the WTRU that includes a RISS measurement support setting message that includes a CW transmission opportunity to enable Received Interrogation Signal Strength (RISS) measurement.

[0114] In step S1605, the network sends unmodulated (CW) transmission to the WTRU, and the WTRU reflects data to the network.

[0115] In step S1607, the network sends unmodulated transmission to the WTRU as announced in the RISS measurement support setting message.

[0116] In step S1609, the WTRU measures its own DL energy harvesting efficiency η.

[0117] In step S1611, the network sends modulated transmission to the WTRU that includes a retransmission request.

[0118] In step S1613, the WTRU has performance metrics, such as

[0119]

Number

[0120] In step S1615, the network sends unmodulated (CW) transmission to the WTRU, and the WTRU reflects a transmission adaptation notification to the network using a pre-set or pre-specified modulation type.

[0121] In step S1617, the network sends unmodulated (CW) transmission to the WTRU, and the WTRU reflects data to the network using the newly selected constellation configuration.

[0122] In one embodiment, the WTRU reports a list of supported constellation configurations for each supported modulation order, using a pre-specified or pre-set modulation type and modulation order having a pre-specified or pre-set arrangement of constellation points. As an example, the WTRU reports a list of supported constellation configurations for each supported modulation using the standard constellation of OOK modulation shown in Figure 2A. As a further example, for instance, the list of constellation configurations supported by the device for secondary modulation includes the standard constellation of QPSK shown in Figure 3A and a second constellation utilizing the zero reflection state (S0) shown in Figure 3B.

[0123] In one embodiment, the WTRU receives a setting for an opportunity to measure the received interrogation signal strength (RISS).

[0124] In one embodiment, the WTRU receives CW transmissions from the network, measures the RISS over one or more measurement opportunities, and determines the DL energy harvesting efficiency (η) associated with the current UL transmission configuration.

[0125] In one embodiment, the WTRU receives a data retransmission request from the network or a notification from the PMU.

[0126] In one embodiment, the WTRU has a performance metric (E H -E TX ) = {ηRISS - P ICM}(N / R) > δ and E TX > Δ, and selects a new constellation configuration from a list of pre-specified UL constellation arrangements. In the formula, P ICM is the power consumption of the ICM when set for the new constellation, N is the UL data packet size, R is the UL data rate, E TX is the UL transmission energy per symbol, and δ and Δ are optimization targets that can be pre-set in the WTRU or signaled by the network as part of the trigger criteria.

[0127] In one embodiment, the WTRU transmits a UL transmission adaptation notification message indicating the newly selected transmission settings to be used in subsequent UL data packets, using a pre-specified / pre-set modulation type and modulation order with a pre-specified / pre-set arrangement of constellation points. If it is assumed that the network can blindly detect which transmission settings were used for data transmission by the WTRU, this embodiment can be omitted in the series of steps performed by the WTRU, as shown in FIG. 15.

[0128] In one embodiment, the WTRU transmits a UL data packet using the new transmission settings that include the new constellation configuration.

[0129] Hybrid phase-amplitude indirect carrier modulation In an indirect carrier modulation transmission system, the UL performance is linked to the DL via the energy harvesting function. For example, a backscatter transponder (e.g., RFID) transmits data in the UL and at the same time harvests energy in the DL using the same RF carrier. FIGS. 4A and 4B show the ICM state transitions and transmission waveforms related to the commonly used Manchester coded on-off keying (OOK) indirect carrier modulation scheme. The shown scheme is used to transmit 1 bit per symbol. This scheme employs a 50% duty cycle factor and divides the symbol period into two equal sections. When transmitting "0", the ICM remains in the reflected state S1 for the first half of the symbol and transitions to the zero reflection state S0 for the second half of the symbol. When transmitting "1", the state transition of the ICM is reversed as shown on the right side.

[0130] The DL energy harvesting efficiency is defined as the portion of the incident RF energy that is harvested and stored in the transponder's battery. The normalized energy harvesting efficiency of the DL is η = E H / E 0 where E 0 is the available incident energy and E H is the harvested energy. The harvested energy E H is defined as follows.

[0131]

Equation

[0132] T is the symbol duration, and Г k is the power reflection coefficient associated with the ICM state used to represent each symbol. In the example shown in FIG. 4A, Г = 0 for S0, Г = 1 for S1, and E H = TP IN / 2. E 0 is calculated assuming that the ICM remains in state S0 (Г = 0) throughout the duration T, and thus E 0 = TPIN and the normalized energy harvesting efficiency η = 50%. Using a similar approach, the transmission energy E per symbol can be obtained and is defined as follows. TX can be obtained and is defined as follows.

[0133]

Equation

[0134] In the example shown in FIG. 4A, Γ = 0 for S0, Γ = 1 for S1, and E TX = TP IN / 2. The gNB receiver decoder uses a data slicer that includes a carrier threshold detector. Since the bit duration and duty cycle factor are specified by the standard, the gNB receiver decoder knows the sampling position of the received waveform.

[0135] FIGS. 5A and 5B show another example of a Manchester coded indirect carrier modulation scheme that employs binary phase shift keying (BPSK) to transmit 1 bit per symbol. This scheme employs a 50% duty cycle factor and divides the symbol period into two equal sections. When transmitting "0", the ICM is in state S1 in the first half of the symbol and transitions to state S2 in the second half of the symbol. As shown in FIGS. 5A and 5B, when transmitting "1", the state transition of the ICM is reversed. Note that for both S1 and S2, Γ = 1 in the example shown in FIG. 5A. Therefore, the harvested energy E H = 0, the normalized energy harvesting efficiency η = 0, and since all incident RF energy is reflected, E TX = TP IN . The gNB receiver decoder uses a phase discriminator. Since the bit duration and duty cycle factor are specified by the standard, the gNB receiver decoder knows where the phase transition is in the received waveform.

[0136] In comparison, the coded indirect carrier modulation method shown in FIGS. 4A and 4B that employs OOK provides better energy harvesting efficiency, and the method shown in FIGS. 5A and 5B that employs BPSK provides higher transmission energy per bit. This represents a certain trade-off between DL energy harvesting efficiency and UL reliability. Thus, a flexible coding modulation method that can provide additional degrees of freedom may be desired so that the trade-off between DL energy harvesting and UL reliability can be made according to the requirements of different use cases and deployment scenarios.

[0137] FIGS. 6A and 6B show a hybrid phase-amplitude indirect carrier modulation method according to an embodiment of the present principle. The illustrated method is for transmitting 1 bit per symbol.

[0138] Generally, such a hybrid phase-amplitude indirect carrier modulation method can be obtained by the UE using hybrid phase-amplitude indirect RF carrier modulation having two degrees of freedom for coded data transmission, and the two degrees of freedom can be the duty cycle factor and the modulation degree. The UE can use changes in the carrier amplitude and carrier phase to encode the data symbol and the symbol boundary. The ICM states can be arranged in two pairs of antipodal reflection states {S1, S2} and {S3, S4}, and the first symbol can be encoded using the duty cycle factor and the transition from state S4 to S1, and the second symbol can be encoded using the duty cycle factor and the transition from state S2 to S3.

[0139] As described above, one degree of freedom is the settable duty cycle coefficient ξ, where 0 < ξ < 1. This means that the data symbol is divided into two parts, ξT and (1 - ξ)T. When the ICM transmits "0", it remains in state S4 during the first ξT part of the symbol and transitions to state S1 during the remaining (1 - ξ)T part of the symbol. When the ICM transmits "1", it remains in state S2 during the first (1 - ξ)T part of the symbol and transitions to state S3 during the remaining ξT part of the symbol. It should be understood that the significance of the state transition can be different, for example, reversed.

[0140] States S1 and S2 can implement the same power reflection coefficient Г 1,2 and states S3 and S4 can implement the same power reflection coefficient Г 3,4 It should be noted that there is a 180-degree phase difference between the reflection waveforms associated with states S1 and S2, and similarly, there is a 180-degree phase difference between the reflection waveforms associated with states S3 and S4. The modulation degree δ is defined as the ratio of the two power reflection coefficients Г 1,2 and Г 3,4 specifically, δ = Г 1,2 / Г 3,4

[0141] The normalized energy harvesting efficiency of DL is η = E H / E 0 where E 0 = TP IN is the available incident energy and E H is the harvested energy. The harvested energy E H is as follows.

[0142]

Equation

[0143]

Number

[0144]

Number

[0145] In the example shown in Figure 6A, assuming that 1,2 = 1 / 2 and ξ = 0.25, the transmission energy per symbol

[0146]

Number

[0147] Based on the reliability of UL transmission and the requirements of power harvesting, the duty cycle factor ξ and the modulation degree δ can be selected as follows.

[0148] The DL energy harvesting efficiency can be improved by reducing the duty cycle factor and increasing the modulation degree.

[0149] The UL reliability (i.e., the transmission energy per bit) can be improved by increasing the duty cycle factor and reducing the modulation degree.

[0150] Figures 7A and 7B illustrate a decoding method for hybrid phase-amplitude indirect carrier modulation transmission according to an embodiment of the present principle. Figure 7A shows a transmission waveform similar to that in Figure 6B, and Figure 7B shows the output waveform of a receiver decoder that employs an amplitude detector and a phase detector.

[0151] The WTRU can use a data slicer (e.g., an amplitude detector) that includes a carrier threshold detector and a phase detector to detect boundaries between data symbols and boundaries within symbols. The allowable settings of the duty cycle factor ξ and the modulation degree δ can be specified by the standard so that the UE can know how to set the threshold of the data slicer and where to sample the output of the data slicer.

[0152] The trade-off between energy harvesting and UL reliability can be achieved by describing the modulation scheme and determining an appropriate combination of values of the parameter pair {ξ, δ} that includes the duty cycle factor ξ and the modulation degree δ. The WTRU can perform automatic constellation adaptation triggered by, for example, a data retransmission request from the network using the following embodiments.

[0153] Figure 17 illustrates an example of a possible transmission method 1700 according to an embodiment of the present principle. In this example, a network 1702 communicates with a WTRU 1704.

[0154] In step S1701, the network sends unmodulated (CW) transmission to the WTRU, and the WTRU reflects back to the network a capability report that includes, for example, a list of supported duty cycle factors ξ and modulation degrees δ.

[0155] In step S1703, the network sends modulated transmission to the WTRU that includes a WTRU setting having a priority regarding at least a part of the list of supported values of the parameter pair {ξ, δ}.

[0156] In step S1705, the network sends an unmodulated (CW) transmission to the WTRU, and the WTRU uses the setting with the highest priority of the parameter pair {ξ, δ} when reflecting the data.

[0157] In step S1707, the network sends a modulated transmission including a first retransmission request to the WTRU.

[0158] In step S1709, the network sends an unmodulated (CW) transmission to the WTRU, and the WTRU uses the setting with the next (i.e., second) highest priority of the parameter pair {ξ, δ} when reflecting the retransmitted data.

[0159] In step S1711, the network sends a modulated transmission including a second retransmission request to the WTRU.

[0160] In step S1713, the network sends an unmodulated (CW) transmission to the WTRU, and the WTRU uses the setting with the next (i.e., third) highest priority of the parameter pair {ξ, δ} when reflecting the retransmitted data.

[0161] In one embodiment, the WTRU reports a list of the supported duty cycle factor ξ and modulation degree δ for hybrid phase - amplitude indirect carrier modulation using a pre - specified / pre - set modulation type.

[0162] In one embodiment, the WTRU receives a priority or ranking for a reported list of supported values of the parameter pair {ξ, δ}. For example, the set of default (highest priority) values for the parameter pair {ξ, δ} for a passive device is the one that provides the highest supported DL energy harvesting efficiency. For example, the default (highest priority) values of the parameter pair {ξ, δ} are the lowest supported duty cycle factor and the highest supported modulation level for optimizing DL energy harvesting. For example, the set of lowest priority values for the parameter pair {ξ, δ} for a passive device is the one that provides the highest UL transmission energy per bit. For example, the lowest priority values for the parameter pair {ξ, δ} are the highest supported duty cycle factor and the lowest supported modulation level for optimizing UL reliability (transmission energy per bit).

[0163] In one embodiment, the WTRU starts data transmission using the default (highest priority) setting of the parameter pair {ξ, δ}.

[0164] In one embodiment, the WTRU receives a data retransmission request or fails to receive an ACK within a pre-specified time window for a pre-specified number of consecutive times that are specified, signaled, or pre-configured.

[0165] In one embodiment, the WTRU retransmits the data by switching to the next configured setting of the parameter pair {ξ, δ} on the priority list.

[0166] In one embodiment, the WTRU continues data transmission using a selected new setting of the parameter pair {ξ, δ} unless it receives an additional data retransmission request from the network. Otherwise, the device selects the next set value for the parameter pair {ξ, δ} on the priority list and retransmits the data. The WTRU continues this process until it exhausts the prioritization list constellation or reaches a pre-configured or signaled total number of retransmissions, after which the WTRU declares a data transmission / connection failure.

[0167] In the following embodiments, a network-assisted procedure is described where the network has full control over which value of the parameter pair {ξ, δ} the WTRU uses. In this case, it is assumed that the network can blindly detect which transmission settings were utilized for data transmission by the WTRU.

[0168] FIG. 18 shows an example of a possible transmission method 1800 according to one embodiment of the present principle. In this example, the network 1802 communicates with the WTRU 1804.

[0169] In step S1801, the network sends a non-modulated (CW) transmission to the WTRU, and the WTRU reflects back to the network a capability report that includes, for example, a list of supported duty cycle factors ξ and modulation levels δ.

[0170] In step S1803, the network sends a modulated transmission to the WTRU that includes a channel quality indicator (CQI) mapping that includes a mapping between the CQI value and at least a portion of the list of supported values for the parameter pair {ξ, δ}.

[0171] In step S1805, the network sends a modulated transmission to the WTRU that includes a CQI measurement assistance setting including a unique ID and a unique ID transmission opportunity (e.g., timing and frequency settings). The unique ID is used for transmission by the device, enabling the network to identify the transmitting device and measure the channel quality associated with the transmitting device.

[0172] In step S1807, the network sends an unmodulated (CW) transmission to the WTRU, and the WTRU reflects the unique ID transmission back to the network.

[0173] In step S1809, the network sends a modulated transmission to the WTRU that includes a CQI measurement report.

[0174] In step S1811, the WTRU selects a parameter pair {ξ, δ} based on the CQI value reported by the network and the configured CQI mapping.

[0175] In step S1813, the network sends an unmodulated (CW) transmission to the WTRU, and the WTRU reflects data back to the network using the selected parameter pair {ξ, δ}.

[0176] In one embodiment, the WTRU reports a list of supported duty cycle coefficients ξ and modulation degrees δ for hybrid phase-amplitude indirect carrier modulation using a pre-specified / pre-configured modulation type.

[0177] In one embodiment, the WTRU receives a mapping between the CQI value and a list of reported values of the parameter pair {ξ, δ}.

[0178] In one embodiment, the WTRU receives a CQI measurement assistance setting, e.g., a unique ID, the period of the unique ID transmission opportunity.

[0179] In one embodiment, the WTRU utilizes the signaling modulation type / modulation order and constellation / symbol setting to periodically transmit a set unique ID, facilitating CQI measurements by the network.

[0180] In one embodiment, the WTRU periodically, or when Q i is in the following relationship

[0181]

Number

[0182] In one embodiment, the WTRU selects the values of the parameter pair {ξ, δ} from the reported list in the first embodiment based on the received pre-set mapping between the CQI value reported by the network and the reported list of values for the CQI value and the parameter pair {ξ, δ}.

[0183] In one embodiment, the WTRU continues data transmission using the selected new values of the parameter pair {ξ, δ}.

[0184] In the following embodiments, a fully autonomous procedure in which the WTRU performs constellation adaptation based on the evaluation of performance metrics will be described.

[0185] FIG. 19 shows an example of a possible transmission method 1900 according to one embodiment of the present principle. In this example, it is assumed that the network 1902 communicates with the WTRU 1904 and that the network can blindly detect which transmission settings were utilized for data transmission by the WTRU.

[0186] In step S1901, the network sends unmodulated (CW) transmission to the WTRU, and the WTRU reflects to the network a capability report including, for example, a list of supported duty cycle factor ξ and modulation degree δ.

[0187] In step S1903, the network sends modulated transmission including a RISS measurement support setting message including a CW transmission opportunity for enabling RISS (Received Inquiry Signal Strength) measurement to the WTRU.

[0188] In step S1905, the network sends unmodulated (CW) transmission to the WTRU, and the WTRU reflects data to the network.

[0189] In step S1907, the network sends unmodulated transmission to the WTRU as announced in the RISS measurement support setting message.

[0190] In step S1909, the WTRU measures its own DL energy harvesting efficiency η.

[0191] In step S1911, the network transmits modulated transmission including a retransmission request to the WTRU.

[0192] In step S1913, the WTRU selects a new constellation configuration based on performance metrics, e.g.,

[0193]

Number

[0194] In step S1915, the network sends a continuous wave (CW) transmission to the WTRU, and the WTRU reflects a transmission adaptation notification to the network using a pre-set or pre-specified modulation type.

[0195] In step S1917, the network sends a CW transmission to the WTRU, and the WTRU reflects data to the network using a newly selected constellation arrangement.

[0196] In one embodiment, the WTRU reports a list of supported duty cycle factors ξ and modulation degrees δ for hybrid phase-amplitude indirect carrier modulation using a pre-specified / pre-set modulation type.

[0197] In one embodiment, the WTRU receives a setting of an opportunity for measuring received inquiry signal strength (RISS).

[0198] In one embodiment, the WTRU receives a CW transmission from the network, measures RISS over one or more measurement opportunities, and determines the downlink energy harvesting efficiency (η) associated with the current UL transmission setting.

[0199] In one embodiment, the WTRU receives a data retransmission request from the network or a notification from the PMU.

[0200] In one embodiment, the WTRU selects a new value of the parameter pair {ξ, δ} from the list reported in the first embodiment such that the performance metric (E H -E TX ) = {ηRISS - P ICM}(N / R) > δ and E TX > Δ is satisfied. Where P ICM is the power consumption of the ICM when set for the new constellation, N is the UL data packet size, R is the UL data rate, E TXis the UL transmission energy per symbol, and δ and Δ are optimization goals that can be pre-set in the UE or signaled by the network as part of the triggering criteria.

[0201] In one embodiment, the WTRU uses a pre-specified / pre-set modulation type and modulation order with a pre-specified / pre-set arrangement of the points of the constellation to send a transmission adaptation notification message indicating the newly selected transmission settings to be used in subsequent UL data packets. This embodiment may be omitted in the series of steps performed by the WTRU shown in FIG. 19 if it is assumed that the network can blindly detect which transmission settings were used for data transmission by the UE.

[0202] In one embodiment, the WTRU transmits a UL data packet using a new transmission setting that includes a new set of values for the parameter pair {ξ, δ}.

[0203] Sparse block code-based indirect carrier modulation In an ICM transmission system, UL performance is tied to DL via an energy harvesting function. For example, a backscatter transponder (e.g., RFID) transmits data on UL while harvesting energy on DL using the same RF carrier. Using a sparse block code in UL can improve DL energy harvesting efficiency when transmission muting is used to represent the "0" entries of the code.

[0204] Figures 8A-8C show an example of a sparse block code (Figure 8A) and the associated carrier modulation scheme, where n bits of data are packed into each symbol and each symbol is represented by a sequence of N = 2 n code bits. In Figure 8A, n = 2 and N = 4. The code representing each data symbol contains only one non-zero entry.

[0205] A general description of the ICM state transitions associated with the symbol sequence is shown in FIG. 8B. A "0" entry in the symbol is represented by setting the ICM to state S0. As shown in FIG. 8B, when the ICM is set to state S0, the load applied to the antenna can be set to match the antenna impedance (e.g., 50 ohms). When the ICM is in state S0, the RF carrier can be fully absorbed. Thus, during the transmission of a "0" entry in the symbol, all or most of the incident RF energy can be absorbed, resulting in the maximum DL energy harvesting efficiency called transmit muting. The ICM transitions, for example, from state S0 to S1 when transmitting a "1" entry in the symbol. State S1 in FIG. 8B represents a short circuit, and thus the incident RF energy is reflected. Thus, during the transmission of a "1" entry in the symbol, all of the incident RF energy can be reflected, resulting in the maximum transmit energy.

[0206] FIG. 8C shows a time-domain description of the transmission waveforms corresponding to each of the {n = 2, N = 4} sparse block codes. The DL energy harvesting efficiency is defined as the portion of the incident RF energy that is harvested and stored in the transponder's battery. The normalized DL energy harvesting efficiency is η = E H / E 0 where E 0 is the available incident energy and E H is the harvested energy. The harvested energy E H is as follows.

[0207]

Equation

[0208]

Equation

[0209] In the example shown in Fig. 8B, Г = 0 for S0, Г = 1 for S1, E TX = T C P IN is.

[0210] Two alternative embodiments of the sparse block coding scheme are shown in Figs. 20A and 20B. Fig. 20A shows a code that implements the maximum sparsity (coding rate = 1 / 2) that provides a DL energy harvesting efficiency η = 75% and a transmission UL energy E TX = T C P IN per symbol. Fig. 20B shows a sparse block code with a coding rate = 2 / 5 that provides a DL energy harvesting efficiency η = 60% and a transmission UL energy E TX = (2 / 5)T C P IN per symbol.

[0211] In indirect carrier modulation transmission, a flexible coding scheme that introduces multiple degrees of freedom may be required to enable a trade-off between DL energy harvesting and UL reliability according to the requirements of various use cases and deployment scenarios. Below, a general overview of how this trade-off can be achieved using a sparse block code is provided.

[0212] The device can increase the sparsity level of the sparse block code or equivalently the rate to improve the DL energy harvesting efficiency.

[0213] Conversely, the device can increase the transmission energy per UL symbol and thus the UL reliability by decreasing the sparsity level of the sparse block code or equivalently the rate.

[0214] The UL reliability adopting the sparse block code-based ICM transmission can be improved by introducing additional degrees of freedom to the sparse block code-based indirect carrier modulation scheme. FIGS. 9A to 9C show a sparse block code according to an embodiment of this principle. FIG. 9A shows the coding scheme, and FIG. 9 shows the ICM state transition.

[0215] Generally, according to this embodiment, the UE uses the phase inversion of the RF carrier to represent the non-zero entries of the sparse block code and transmits the phase inversion in the data coding sequence using the transition between the pair of antipodal reflected states {S1, S2} of the ICM. By mapping the antipodal reflected states of the ICM to the open and short terminations of the antenna, the transmission reliability can be improved. The UE can use one of the reflected states from the antipodal pair to transmit the reference phase for the phase coherent indirect carrier modulation transmission, and can use the directional transition between the pair of antipodal reflected states {S1, S2} to indicate the change in the phase inversion direction.

[0216] The "0" entry of the symbol can be represented by setting the ICM to state S0. When transmitting the "1" entry of the symbol, the ICM can transition from state S0 to S1 and then to S2. State S1 in FIG. 9B can represent a short circuit, and state S2 can represent an open circuit. Both state S1 and state S2 can reflect all of the incident RF energy, but as a result of transitioning from state S1 to S2, the carrier phase is inverted. FIG. 9C shows a time-domain description of the transmission waveform corresponding to each of the {n = 2, N = 4} sparse block codes.

[0217] In the first case, the harvesting efficiency η and the transmission energy E per symbol TX It should be noted that they are the same in the two approaches described in FIGS. 8A - 8C and FIGS. 9A - 9C. However, the transmission method described in FIGS. 9A - 9C can improve the UL reliability by introducing additional degrees of freedom by introducing a phase inversion at the center of the sine wave packet representing the "1" entry of the sparse block code. Subsequently, the UE can use a decoder that employs both an amplitude detector and a phase detector. The load modulator of the UE's transponder is expected to consume more power because it performs three state transitions of the antenna load instead of two during the transmission of the "1" entry of the sparse block code, which may slightly reduce the overall energy efficiency of the UE.

[0218] High - density block - code - based indirect carrier modulation In an indirect carrier modulation transmission system, the UL performance is linked to the DL via the energy harvesting function. For example, a backscatter transponder (e.g., RFID) transmits data in the UL and at the same time harvests energy in the DL using the same RF carrier. Using a high-density block code where a perfect reflection state (e.g., S1 in Fig. 21B showing the ICM state transition) is used to represent the "1" entry of the high-density block code, the UL reliability can be improved by increasing the transmission energy per symbol. An example of a high-density block code and the associated carrier modulation scheme is shown in Figs. 21A and 21B, where n-bit data is packed into each symbol and each symbol is represented by a sequence of N = 2n coded bits. In Fig. 21A, n = 2 and N = 4. The code representing each data symbol contains only one zero entry.

[0219] A rough description of the state transition of the ICM associated with the code sequence is shown in Fig. 21B. The "0" entry in the code is represented by setting the ICM to state S0. As shown in Fig. 21B, when the ICM is set to state S0, the load added to the antenna is set to match the antenna impedance (e.g., 50 ohms). When the ICM is in state S0, the RF carrier is completely absorbed. Thus, during the transmission of the "0" entry in the code, all or most of the incident RF energy is absorbed. The ICM transitions, for example, from state S0 to S1 when transmitting the "1" entry in the code. State S1 in Fig. 21B represents a short circuit, and thus all of the incident RF energy is reflected. Thus, during the transmission of the "1" entry in the code, all of the incident RF energy is reflected, resulting in maximum transmission energy.

[0220] A time-domain description of the transmission waveform corresponding to each of the high-density block codes of {n = 2, N = 4} is shown in Fig. 22. The DL energy harvesting efficiency is defined as the portion of the incident RF energy that is harvested and stored in the transponder's battery. The normalized energy harvesting efficiency of the DL is η = E H / E0 and E 0 is the available incident energy, and E H is the harvested energy. The harvested energy E H is defined as follows.

[0221]

Equation

[0222] T C is the duration of each element of the high - density block code, and Г k is the power reflection coefficient associated with the ICM state used to represent each code entry. In the case of the example shown in Figure 21B, for S 0 Г = 0, and for S 1 Г = 1, and E H = T C P IN is. E 0 is calculated assuming that the ICM remains in state S 0 (Г = 0) for all four code entries, and thus E 0 = 4T C P IN is, and the normalized energy harvesting efficiency η = 25%. Using a similar approach, the transmission energy E TX per symbol can be obtained as follows.

[0223]

Equation

[0224] In the example shown in Figure 21B, for S 0 Г = 0, for S 1 Г = 1, and E TX =(3 / 4)T C P IN is.

[0225] Two alternative embodiments of the high-density block coding scheme are shown in FIGS. 23A and 23B. FIG. 23A shows a code implementing the maximum density (code rate = 1 / 2) that provides a DL energy harvesting efficiency η = 25% and a transmission UL energy E per symbol TX =(3 / 4)T C P IN FIG. 23B shows a high-density block code with a rate = 2 / 5 that provides a DL energy harvesting efficiency η = 40% and a transmission UL energy E per symbol TX =(3 / 5)T C P IN In indirect carrier modulation transmission, a flexible coding scheme that introduces multiple degrees of freedom may be required to enable a trade-off between DL energy harvesting and UL reliability according to the requirements of various use cases and deployment scenarios. Below, a general overview of how this trade-off can be achieved using high-density block codes is provided.

[0226] The device can increase the density level of the high-density block code or equivalently the rate to increase the transmission energy per UL symbol and thus the UL reliability. Conversely, the device can decrease the density level of the high-density block code or equivalently the rate to improve the DL energy harvesting efficiency.

[0227]

[0228] UE Procedure As already explained, a UE can receive power and transmit information simultaneously on the same RF carrier. The UE can operate in an ICM transmission system to enable efficient DL energy harvesting (EH) and reliable UL data transmission simultaneously. The desired trade-off between EH and UL reliability can be obtained by determining the constellation type (e.g., ICM, hybrid phase-amplitude ICM, sparse block code ICM, high density block code ICM) for a corresponding modulation order (i.e., a specific number of constellation points) and selecting a constellation / symbol setting that optimizes the DL EH efficiency for a specified UL transmission reliability. This can be, in a broad sense, either network control or UE control.

[0229] In an embodiment of method 1000 according to this principle, as shown in FIG. 10, the UE can perform constellation adaptation after a data retransmission request from the network.

[0230] In step S1002, the UE reports to the network a list of supported class(es) or supported modulation type(s) / modulation order(s) and corresponding constellation / symbol settings, using an essential standardized modulation type / modulation order with a specific constellation / symbol setting.

[0231] In step S1004, the UE receives a priority or ranking (per modulation order) for the reported list of modulation and constellation settings, where the default constellation type (i.e., the one with the highest priority) provides the highest DL energy harvesting efficiency supported, and the constellation with the lowest priority provides the highest UL transmission energy per bit for a given modulation order.

[0232] In step S1006, the UE transmits data using the highest-priority constellation that provides the highest supported DL energy harvesting efficiency.

[0233] In step S1008, the UE receives a data retransmission request or fails to receive an ACK within a specified time window for a specified signaling / pre-set consecutive number of times.

[0234] In step S1010, the UE switches to the next configured constellation and modulation type on the priority list and retransmits the data.

[0235] In step S1012, the UE continues data transmission using the selected constellation and modulation type as long as it does not receive a retransmission request or receives an ACK (see step S1008). Otherwise, the UE repeats step S1010 until it exhausts the constellations on the priority list or reaches the pre-set total number of retransmissions, and declares a failure in data transmission / connection when it exhausts the constellations or reaches the total number of retransmissions.

[0236] In the default (i.e., highest priority) constellation setting in step S1004, the zero reflection state of ICM can be utilized as a point of the UL signal constellation for efficient DL EH. This constellation setting can be a hybrid phase-amplitude indirect carrier modulation scheme with the lowest supported duty cycle factor and the highest supported modulation degree for efficient DL EH, or a sparse block code-based indirect carrier modulation scheme with the maximum number of supported zero reflection states per symbol.

[0237] The lowest-priority constellation in step S1004 can be a hybrid phase-amplitude indirect carrier modulation scheme having the highest supported duty cycle factor and the lowest supported modulation degree, or a sparse block code-based indirect carrier modulation scheme including phase reversal of sine wave packets representing non-zero code entries.

[0238] In the method shown in FIG. 10, the UE determines which modulation type / modulation order and associated constellation settings to use based on assistance information from the network in the form of a priority / ranking list.

[0239] FIG. 11 shows a method 1100 according to an embodiment of the present principle in which the UE completely controls which modulation type / modulation order and constellation settings to use without assistance information from the network. Here, it is assumed that the network can blindly detect which transmission settings were used for data transmission by the UE. In this embodiment, the UE can perform constellation adaptation based on channel quality indicator (CQI) measurement values reported by the network.

[0240] In step S1102, the UE reports the supported class(es), or the list of supported modulation type(s) / modulation order(s) and the corresponding received constellation / symbol settings for each supported modulation type, using an essential standardized modulation type / modulation order having a specific constellation / symbol setting.

[0241] In step S1104, the UE receives a mapping between the CQI value and the modulation type / modulation order and the corresponding constellation / symbol settings based on the reported values.

[0242] In step S1106, the UE receives CQI measurement assistance settings, for example, a unique ID, the period of the unique ID transmission opportunity, and modulation type / modulation order and constellation / symbol settings.

[0243] In step S1108, the UE uses the signaling modulation type / modulation order and constellation / symbol settings to transmit the set unique ID, for example, periodically, to facilitate CQI measurement by the network.

[0244] In step S1110, the UE receives from the network the currently measured CQI value (Q i ) periodically, or when Q i satisfies the following relationship

[0245]

Equation

[0246] In step S1112, the UE selects a constellation type from a pre-set list based on the CQI value reported by the network and a pre-set mapping.

[0247] In step S1114, the UE continues data transmission using the selected modulation type / modulation order and constellation settings.

[0248] FIG. 12 shows a method 1200 according to an embodiment of the present principle in which the UE performs constellation adaptation based on the constellation type settings received from the network.

[0249] In step S1202, the UE reports a list of supported class(es) or supported modulation type(s) / modulation order(s) and corresponding constellation / symbol settings, using a mandatory standardized modulation type / modulation order with a specific constellation / symbol setting.

[0250] In step S1204, the UE receives a priority or ranking (per modulation order) for the reported list of modulation and constellation settings, where the default constellation type (highest priority) can be the one that provides the highest DL energy harvesting efficiency supported, and the lowest priority constellation can be the one that provides the highest UL transmission energy per bit for a given modulation order.

[0251] In step S1206, the UE receives a CQI measurement opportunity setting for facilitating CQI measurement by the network, e.g., a unique ID, modulation type / modulation order, and constellation / symbol setting.

[0252] In step S1208, the UE transmits the set unique ID in the allocated measurement opportunity, using the signaled modulation type / modulation order and constellation / symbol setting.

[0253] In step S1210, the UE receives from the network a priority value indicating the modulation type / modulation order and constellation setting to be used first for data transmission.

[0254] In step S1212, the UE receives a data retransmission request or fails to receive an ACK within a pre-specified time window for a specified signaling / pre-set consecutive number of times.

[0255] In step S1214, the UE switches to the next configured constellation and modulation type on the priority list and retransmits the data.

[0256] In step S1216, the UE continues data transmission using the selected constellation and modulation type as long as it does not receive a retransmission request or fails to receive an ACK (see step S1212). Otherwise, it repeats step S1214 until it exhausts the constellations on the priority list or reaches the signaling or preconfigured total number of retransmissions, and declares a data transmission / connection failure when it exhausts the constellations or reaches the total number of retransmissions. This method can return to step S1206.

[0257] The default (highest priority) constellation setting (see S1204) can utilize the zero reflection state of ICM as a point of the UL signal constellation for efficient DL EH. This constellation setting can be a hybrid phase-amplitude indirect carrier modulation scheme having the lowest duty cycle factor supported for efficient DL EH and the highest modulation order supported, or a sparse block code-based indirect carrier modulation scheme having the maximum number of supported zero reflection states per symbol.

[0258] The lowest priority constellation (see step S1204) can be a hybrid phase-amplitude indirect carrier modulation scheme having the highest duty cycle factor supported and the lowest modulation order supported, or a sparse block code-based indirect carrier modulation scheme including phase reversal of sine wave packets representing non-zero code entries.

[0259] FIG. 13 shows a method 1300 according to an embodiment of this principle in which the UE performs constellation adaptation based on the evaluation of performance metrics.

[0260] In step S1302, the UE reports a list of supported class(es) or supported modulation type(s) / modulation order(s) and corresponding constellation / symbol settings using a mandatory standardized modulation type / modulation order having a specific constellation / symbol setting.

[0261] In step S1304, the UE receives a transmission adaptation notification message setting, e.g., transmission period or trigger criterion and related parameters, modulation type / modulation order, and constellation setting.

[0262] In step S1306, the UE receives a setting for an opportunity to measure the received inquiry signal strength (RISS), e.g., opportunity type (single measurement opportunity or non-single, i.e., resources are used for both measurement and UL data transmission), opportunity period, modulation type / modulation order and constellation setting associated with UL transmission in a non-single opportunity.

[0263] In step S1308, the UE measures the RISS over one or more measurement opportunities and determines the DL energy harvesting efficiency (η) associated with the current UL transmission setting.

[0264] In step S1310, the UE receives a data retransmission request from the network or a notification from the Power Management Unit (PMU), and selects a new constellation from a pre-specified list of UL constellation types such that the performance metric (E H -E TX ) = {ηRISS - P ICM}(N / R) > δ and E TX > Δ. Where P ICM is the power consumption of the ICM when set for the new constellation, N is the UL data packet size, R is the UL data rate, E TXis the UL transmission energy per symbol, and δ and Δ are optimization targets that can be pre-set in the UE or signaled by the network as part of the triggering criteria.

[0265] In step S1312, the UE uses the pre-set / signaled transmission settings and transmits a transmission adaptation notification message indicating the newly selected transmission settings to be used in subsequent UL data packets.

[0266] In step S1314, the UE transmits the UL data packet using the new transmission settings.

[0267] In one embodiment of method 2400 according to this principle, shown in FIG. 24, the UE can perform constellation adaptation after a data retransmission request from the network.

[0268] In step S2402, the UE reports to the network a list of supported class(es) or supported modulation type(s) / modulation order(s) and corresponding constellation / symbol settings, using a mandatory standardized modulation type / modulation order with a specific constellation / symbol setting.

[0269] In step S2404, the UE receives a priority or ranking (per modulation order) for the reported list of modulation and constellation settings, where the default constellation type (i.e., the one with the highest priority) provides the highest DL energy harvesting efficiency supported, and the lowest priority constellation provides the highest UL transmission energy per bit for a given modulation order.

[0270] In step S2406, the UE transmits the data using the highest priority constellation that provides the highest DL energy harvesting efficiency supported.

[0271] In step S2408, the UE either receives a data retransmission request or fails to receive an ACK within a pre-specified time window for a specified signaling / pre-set consecutive number of times.

[0272] In step S2410, the UE switches to the next configured constellation and modulation type on the priority list and retransmits the data.

[0273] In step S2412, the UE continues data transmission using the selected constellation and modulation type as long as it does not receive a retransmission request or receives an ACK (see step S1008). Otherwise, the UE repeats step S2410 until it exhausts the constellations on the priority list or reaches the total pre-set retransmission number specified by signaling. When it exhausts the constellations or reaches the total retransmission number, the UE declares a failure in data transmission / connection.

[0274] In the default (highest priority) constellation setting for, e.g., a passive device in step S2404, the zero reflection state of ICM can be utilized as a point of the UL signal constellation for efficient DL EH.

[0275] In the default (highest priority) constellation setting for, e.g., a passive device in step S2404, it can be a hybrid phase-amplitude indirect carrier modulation scheme having the lowest supported duty cycle factor and the highest supported modulation degree for efficient DL EH.

[0276] In the default (highest priority) constellation setting for, e.g., a passive device in step S2404, it can be a sparse block code-based indirect carrier modulation scheme having the maximum number of supported zero reflection states per symbol (i.e., maximum sparsity, highest code rate).

[0277] In step S2404, the default (highest priority) constellation setting for, for example, a passive device can be a high-density block code-based indirect carrier modulation scheme (i.e., minimum density, lowest code rate) having the maximum number of supported zero reflection states per symbol.

[0278] In step S2404, the lowest priority constellation for, for example, a passive device can be a hybrid phase-amplitude indirect carrier modulation scheme having the highest supported duty cycle factor and the lowest supported modulation degree.

[0279] In step S2404, the lowest priority constellation setting for, for example, a passive device can be a high-density block code-based indirect carrier modulation scheme having the maximum number of supported full reflection states per symbol (i.e., maximum density, highest code rate).

[0280] In step S2404, the lowest priority constellation setting for, for example, a passive device can be a sparse block code-based indirect carrier modulation scheme (i.e., minimum sparsity, lowest code rate) having the maximum number of supported full reflection states per symbol.

[0281] In step S2404, the lowest priority constellation for, for example, a passive device can be a sparse block code-based indirect carrier modulation scheme including phase inversion of sine wave packets representing non-zero code entries.

[0282] In the method shown in FIG. 24, the UE determines which modulation type / modulation order and associated constellation setting to use based on assistance information from the network in the form of a priority / ranking list.

[0283] Figure 25 shows a method 2500 according to an embodiment of the present principle, in which a UE performs constellation adaptation based on a constellation type setting received from a network.

[0284] In step S2502, the UE reports a list of supported class(es) or supported modulation type(s) / modulation order(s) and corresponding constellation / symbol settings, using a mandatory standardized modulation type / modulation order having a specific constellation / symbol setting.

[0285] In step S2504, the UE receives a priority or ranking for the reported list of modulation and constellation settings (per modulation order).

[0286] The priority or ranking can include a default modulation / constellation type (highest priority) that provides the highest supported DL energy harvesting efficiency, for example, suitable for a battery-less passive device. Alternatively, the priority or ranking can include a default modulation / constellation type (highest priority) that provides the highest UL transmission energy per bit for a given modulation order, for example, suitable for an active device having an on-board battery.

[0287] The priority or ranking can include the lowest priority constellation that provides the highest UL transmission energy per bit for a given modulation order, for example, suitable for a battery-less passive device. Alternatively, the priority or ranking can include the lowest priority constellation that provides the highest supported DL energy harvesting efficiency, for example, suitable for an active device having an on-board battery.

[0288] In step S2506, the UE receives a CQI measurement opportunity setting for facilitating CQI measurement by the network, for example, a unique ID, modulation type / modulation order, and constellation / symbol setting.

[0289] In step S2508, the UE transmits the set unique ID in the allocated measurement opportunity using the signaled modulation type / modulation order and constellation / symbol setting.

[0290] In step S2510, the UE receives from the network a priority value indicating the modulation type / modulation order and constellation setting to be used first for data transmission.

[0291] In step S2512, the UE either receives a data retransmission request or fails to receive an ACK within a pre-specified time window for a specified signaling / pre-set number of consecutive times.

[0292] In step S2514, the UE switches to the next set constellation and modulation type on the priority list and retransmits the data.

[0293] In step S2516, the UE continues data transmission using the selected constellation and modulation type as long as it does not receive a retransmission request or fails to receive an ACK (see step S2512). Otherwise, the UE repeats step S2514 until it exhausts the constellations on the priority list or reaches the total number of pre-set retransmissions signaled, and declares a failure in data transmission / connection when it exhausts the constellations or reaches the total number of retransmissions. This method can return to step S2506.

[0294] For example, in the default (highest priority) constellation setting for a passive device (see step S2504), the zero reflection state of the ICM can be used as a point of the UL signal constellation for efficient DL EH. This constellation setting can be a hybrid phase-amplitude indirect carrier modulation scheme having the lowest supported duty cycle factor and the highest supported modulation degree for efficient DL EH, or a sparse block code-based indirect carrier modulation scheme having the largest number of supported zero reflection states per symbol (i.e., maximum sparsity, highest code rate), or a high-density block code-based indirect carrier modulation scheme having the largest number of supported zero reflection states per symbol (i.e., minimum density, lowest code rate).

[0295] For example, the lowest priority constellation for a passive device (see step S2504) can be a hybrid phase-amplitude indirect carrier modulation scheme having the highest supported duty cycle factor and the lowest supported modulation degree, or a high-density block code-based indirect carrier modulation scheme having the largest number of supported full reflection states per symbol (i.e., maximum density, highest code rate), or a sparse block code-based indirect carrier modulation scheme having the largest number of supported full reflection states per symbol (i.e., minimum sparsity, lowest code rate), or a sparse block code-based indirect carrier modulation scheme including phase inversion of sine wave packets representing non-zero code entries.

[0296] Although the features and elements are described above in specific combinations, one of ordinary skill in the art will appreciate that each feature or element can be used alone or in any combination with other features and elements. Further, the methods described herein can be implemented in a computer program, software, or firmware incorporated in a computer-readable medium for execution by a computer or processor. Examples of computer-readable media include electronic signals (transmitted via wired or wireless connection) and computer-readable storage media. Examples of computer-readable storage media include, but are not limited to, magnetic media such as read-only memory (ROM), random access memory (RAM), registers, cache memory, semiconductor memory devices, 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 of operation by a wireless transmit / receive unit, i.e., a WTRU, the method comprising: selecting means for selecting a constellation from a set of constellations corresponding to symbol settings of indirect carrier modulation, i.e., ICM, based on at least one constellation performance effectiveness indicator, each constellation performance effectiveness indicator corresponding to a constellation of the set of constellations; energy harvesting means and transmitting means for using the selected constellation and symbol settings to harvest energy and transmit data simultaneously; A method comprising the above.

2. The method according to claim 1, further comprising evaluation means for evaluating at least one of the constellation performance effectiveness indicators for the corresponding constellation based on downlink energy harvesting, i.e., DL EH efficiency and uplink, i.e., UL, data transmission reliability.

3. The method according to claim 2, further comprising measuring means for measuring received signal strength and the downlink energy harvesting efficiency.

4. The constellation performance effectiveness indicator includes at least one of the quantities ηRISS, PICM, and ETX, and the constellation is selected such that each of the at least one quantity included in the constellation performance effectiveness indicator satisfies the respective conditions ηRISS > ε, PICM < θ, and ETX > Δ, where η is the energy harvesting efficiency, RISS is the measured received signal strength, PICM is the power consumption of the ICM, ETX is the uplink transmission energy per symbol, and θ, ε, and Δ are target values. The method according to claim 3.

5. The constellation is selected such that (ηRISS - PICM)(N / R) > δ and a second effectiveness indicator ETX > Δ, where N is the uplink data packet size, R is the uplink data rate, and δ is a target value. The method according to claim 4.

6. The method according to claim 1, further comprising selecting means for selecting the symbol settings.

7. The method according to claim 1, further comprising transmitting means for transmitting a notification of the selected constellation and symbol settings.

8. The constellation is the method according to claim 1, which defines the arrangement of constellation points.

9. The symbol setting is the method according to claim 1, which defines the number of bits per symbol.

10. The constellation is the method according to claim 1, which is determined by the impedance state of an indirect carrier modulator.

11. A wireless transmit / receive unit, i.e., a WTRU, comprising: An antenna configured to transmit data; An energy harvester configured to harvest energy; At least one hardware processor configured to select a constellation from a set of constellations corresponding to symbol settings of indirect carrier modulation, i.e., ICM, based on at least one constellation performance effectiveness metric, where each constellation performance effectiveness metric corresponds to a constellation in the set of constellations; and at least one hardware processor; The WTRU uses the selected constellation and symbol setting to harvest energy and transmit data simultaneously.

12. The at least one hardware processor is further configured to evaluate, for the corresponding constellation, at least one of the constellation performance effectiveness metrics based on downlink energy harvesting, i.e., DL EH efficiency, and uplink, i.e., UL data transmission reliability, according to the WTRU of claim 11.

13. The at least one hardware processor is further configured to measure received signal strength and the downlink energy harvesting efficiency according to the WTRU of claim 12.

14. The constellation performance effectiveness indicator includes at least one of the quantities ηRIS S, PICM, and ETX, and the at least one hardware processor is configured to select the constellation such that the at least one quantity included in the constellation performance effectiveness indicator satisfies the respective conditions ηRIS S > ε, PICM < θ, and ETX > Δ, where η is the energy harvesting efficiency, RIS S is the measured received signal strength, PICM is the power consumption of the ICM, ETX is the uplink transmission energy per symbol, and θ, ε, and Δ are target values, the WTRU according to claim 13.

15. The at least one hardware processor is configured to select the constellation such that (ηRIS S - PICM)(N / R) > δ and a second effectiveness indicator ETX > Δ, where N is the uplink data packet size, R is the uplink data rate, and δ is a target value, the WTRU according to claim 14.

16. The at least one hardware processor is further configured to select the symbol setting, the WTRU according to claim 11.

17. The at least one hardware processor is further configured to transmit a notification of the selected constellation and symbol setting via the antenna, the WTRU according to claim 11.

18. The constellation defines the arrangement of constellation points, the WTRU according to claim 11.

19. The symbol setting defines the number of bits per symbol, the WTRU according to claim 11.

20. The constellation is determined by the impedance state of an indirect carrier modulator, the WTRU according to claim 11.

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