Method and wtru for providing range extension for WLAN

Abstract

To provide a method and apparatus for enabling WLAN devices to perform HARQ scheduling and media access in 6GHz bands, as well as longer range HARQ transmissions.SOLUTION: A method for use in a station (STA) comprises receiving low rate range extension (LRRE) information from an AP and determining whether a first condition is satisfied. The method includes transmitting a mode change request to the AP to change the mode of operation to an LRRE hybrid automatic repeat request (HARQ) mode on a condition that a first condition is met, receiving a response to the mode change request from the AP, and communicating with the AP using a plurality of physical layer convergence procedure (PLCP) protocol data units (PPDUs). Each of the plurality of PPDUs includes at least one field enabling transmission between the STA and the AP under a first condition, and an LRREHARQ mode indication.SELECTED DRAWING: Figure 8A

Description

[Technical Field]

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS This application claims the benefit of U.S. Provisional Patent Application No. 62 / 790,810, filed January 10, 2019, the contents of which are incorporated herein by reference. [Background technology]

[0002] Hybrid Automatic Repeat Request (HARQ) is a transmission error control technique in wireless communication networks. It relies on a combination of error correction codes and retransmissions. In unlicensed spectrum, such as the 6 GHz band, there are currently no conventional wireless local area network (WLAN) devices operating on the 6 GHz band. Therefore, there is a need for a method and apparatus that enables WLAN devices to perform HARQ scheduling and medium access in the 6 GHz band, as well as HARQ transmissions over longer ranges. Summary of the Invention

[0003] 1. A method for use in a wireless transmit / receive unit (WTRU), the method including: receiving slow range extension (LRRE) information from an access point (AP), determining whether a first condition is met by the WTRU, sending a mode change request to the AP to change an operating mode to an LRRE hybrid automatic repeat request (HARQ) mode on condition that the first condition is met, receiving a response regarding the mode change request from the AP, and communicating with the AP using a plurality of physical layer convergence procedure (PLCP) protocol data units (PPDUs), each of the plurality of PPDUs comprising at least one field that enables transmission between the WTRU and the AP under the first condition and an LRRE HARQ mode indication.

[0004] a wireless transmit / receive unit (WTRU), the WTRU including: a receiver configured to receive slow rate range extension (LRRE) information from an access point (AP); a transmitter; and a processor configured to determine whether a first condition is satisfied by the WTRU, wherein on condition that the first condition is satisfied, the transmitter is further configured to send a mode change request to the AP to change the operation mode to a LRRE hybrid automatic repeat request (HARQ) mode, the receiver is further configured to receive a response regarding the mode change request from the AP, the WTRU is configured to communicate with the AP using a plurality of physical layer convergence procedure (PLCP) protocol data units (PPDUs), each of the plurality of PPDUs comprising at least one field enabling transmission between the WTRU and the AP under the first condition and an LRRE HARQ mode indication.

[0005] 1. A method for use in a wireless transmit / receive unit (WTRU), the method including: receiving slow range extension (LRRE) information from an access point (AP); determining whether a first condition is satisfied by the WTRU, the first condition being satisfied when a channel quality of a channel used by the WTRU is less than a channel quality value; receiving a mode change request from the AP to change an operating mode to an LRRE hybrid automatic repeat request (HARQ) mode on condition that the first condition is satisfied; sending a response regarding the mode change request to the AP; and communicating with the AP using a plurality of physical layer convergence procedure (PLCP) protocol data units (PPDUs), each of the plurality of PPDUs including at least one field that enables transmission between the WTRU and the AP under the first condition and an LRRE HARQ mode indication. [Brief explanation of the drawings]

[0006] A more detailed understanding may be had from the following description, given by way of example in conjunction with the accompanying drawings, in which like reference numerals indicate similar elements and in which: [Figure 1A]FIG. 1 is a system diagram illustrating an example communication system in which one or more disclosed embodiments may be implemented. [Figure 1B] 1B is a system diagram illustrating an example wireless transmit / receive unit (WTRU) that may be used within the communications system shown in FIG. 1A, according to an embodiment. [Figure 1C] 1B is a system diagram illustrating an example radio access network (RAN) and an example core network (CN) that may be used within the communication system shown in FIG. 1A, according to an embodiment. [Figure 1D] 1B is a system diagram illustrating a further exemplary RAN and a further exemplary CN that may be used within the communication system shown in FIG. 1A, according to an embodiment. [Figure 2] FIG. 1 illustrates exemplary hybrid automatic repeat request (HARQ) goodput performance with collisions. [Figure 3] FIG. 1 illustrates an example of a collision-aware HARQ receiver. [Figure 4] FIG. 4 illustrates exemplary performance of the collision-aware HARQ receiver shown in FIG. 3. [Figure 5] FIG. 1 illustrates an exemplary beacon interval having a time division duplex (TDD) interval. [Figure 6] FIG. 1 illustrates an exemplary detailed TDD interval structure. [Figure 7] FIG. 1 illustrates an exemplary procedure for HARQ across TDD boundaries. [Figure 8A] 1 illustrates a method for providing range extension for a WLAN according to a first embodiment of the present application; [Figure 8B] FIG. 2 illustrates a method for providing range extension for a WLAN according to a second embodiment of the present application. [Figure 8C] FIG. 10 illustrates a method for providing range extension for a WLAN according to a third embodiment of the present application. [Figure 8D] FIG. 10 illustrates a method for providing range extension for a WLAN according to a fourth embodiment of the present application. [Figure 9]FIG. 1 illustrates a High Efficiency (HE) 6 GHz Physical Protocol Data Unit (PPDU) according to the present application. [Figure 10] 1 illustrates an Extremely High Throughput (EHT) 6GHz PPDU format according to the present application. [Figure 11] FIG. 1 illustrates an EHT PPDU format for multiple frequency bands according to the present application. [Figure 12] FIG. 2 illustrates a frequency selective channel according to the present application. [Figure 13] 1 illustrates a cell edge station (STA) using 2.4 GHz target wake time (TWT) service period (SP) to bootstrap 5 / 6 GHz uplink (UL) resource unit (RU) allocation in accordance with the present application. [Figure 14] FIG. 1 illustrates an exemplary powerless collision estimation midamble in accordance with the present application. [Figure 15] FIG. 1 illustrates an exemplary partial power collision estimation midamble in accordance with the present application. [Figure 16] FIG. 1 illustrates an exemplary joint Doppler and collision estimation midamble according to the present application. [Figure 17] FIG. 1 illustrates an exemplary Doppler midamble punctured for collision estimation in accordance with the present application. [Figure 18] FIG. 2 illustrates an exemplary unpowered resource unit for collision estimation in accordance with the present application. [Figure 19] FIG. 1 illustrates an exemplary procedure for collision estimation in collision-aware HARQ according to the present application. [Figure 20] FIG. 1 illustrates an exemplary receiver-initiated collision estimation resource modification according to the present application. DETAILED DESCRIPTION OF THE INVENTION

[0007] 1A illustrates an example communication system 100 in which one or more disclosed embodiments may be implemented. The communication system 100 may be a multiple-access system that provides content, such as voice, data, video, messaging, and broadcasts, to multiple wireless users. The communication system 100 enables the multiple wireless users to access such content through the sharing of system resources, including wireless bandwidth. For example, the communication system 100 may employ one or more channel access methods, such as code division multiple access (CDMA), time division multiple access (TDMA), frequency division multiple access (FDMA), orthogonal FDMA (OFDMA), single-carrier FDMA (SC-FDMA), zero-tail unique word discrete Fourier transform extended OFDM (ZT-UW-DFT-S-OFDM), unique word OFDM (UW-OFDM), resource block filtered OFDM, filter bank multicarrier (FMBC), etc.

[0008] 1A, communications 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, although it will be appreciated that the disclosed embodiments contemplate any number of WTRUs, base stations, networks, and / or network elements. Each of WTRUs 102a, 102b, 102c, 102d may be any type of device configured to operate and / or communicate in a wireless environment. For example, the WTRUs 102a, 102b, 102c, 102d, any of which may be referred to as a station (STA), may be configured to transmit and / or receive wireless signals and may include user equipment (UE), mobile stations, fixed or mobile subscriber units, subscription-based units, pagers, mobile phones, personal digital assistants (PDAs), smartphones, laptops, netbooks, personal computers, wireless sensors, hotspot or Mi-Fi devices, IoT devices, watches or other wearables, head-mounted displays (HMDs), vehicles, drones, medical devices and applications (e.g., remote surgery), industrial devices and applications (e.g., robots and / or other wireless devices operating within an industrial and / or automation processing chain context), consumer electronics devices, devices operating on commercial and / or industrial wireless networks, etc. Any of the WTRUs 102a, 102b, 102c, and 102d may be referred to interchangeably as a UE.

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

[0010] The base station 114a may be part of the RAN 104, which may also include other base stations and / or network elements (not shown), such as a base station controller (BSC), a radio network controller (RNC), relay nodes, etc. The base station 114a and / or base station 114b may be configured to transmit and / or receive wireless signals on one or more carrier frequencies, which may be referred to as a cell (not shown). These frequencies may be in the licensed spectrum, the unlicensed spectrum, or a combination of the licensed and unlicensed spectrum. A cell may provide coverage for wireless services in a specific geographic area, which may be relatively fixed or which may change over time. A cell may be further divided into cell sectors. For example, the cell associated with the base station 114a may be divided into three sectors. Thus, in one embodiment, the base station 114a may include three transceivers, i.e., one for each sector of the cell. In an embodiment, the base station 114a may employ multiple-input multiple-output (MIMO) technology and utilize multiple transceivers for each sector of the cell. For example, beamforming may be used to transmit and / or receive signals in desired spatial directions.

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

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

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

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

[0015] In an embodiment, the base station 114a and the WTRUs 102a, 102b, 102c may implement multiple radio access technologies. For example, the base station 114a and the WTRUs 102a, 102b, 102c may jointly implement LTE radio access and NR radio access, e.g., using a dual connectivity (DC) principle. Thus, the air interface utilized by the WTRUs 102a, 102b, 102c may be characterized by multiple types of radio access technologies and / or transmissions sent to / from multiple types of base stations (e.g., eNBs and gNBs).

[0016] In other embodiments, the base station 114a and the WTRUs 102a, 102b, 102c may implement a wireless technology such as IEEE 802.11 (i.e., Wireless Fidelity (WiFi)), IEEE 802.16 (i.e., Worldwide Interoperability for Microwave Access (WiMAX)), CDMA2000, CDMA2000 1X, CDMA2000EV-DO, Interim Standard 2000 (IS-2000), Interim Standard 95 (IS-95), Interim Standard 856 (IS-856), Global System for Mobile Communications (GSM), Enhanced Data Rates for GSM Evolution (EDGE), GSM EDGE (GERAN), or the like.

[0017] 1A may be, for example, a wireless router, a Home NodeB, a Home eNodeB, or an access point and may utilize any suitable RAT for facilitating wireless connectivity within a localized area, such as a workplace, a home, a vehicle, a campus, an industrial facility, an air corridor (e.g., for use by drones), a roadway, etc. In one embodiment, the base station 114b and the WTRUs 102c, 102d may implement a radio technology such as IEEE 802.11 to establish a wireless local area network (WLAN). In an embodiment, the base station 114b and the WTRUs 102c, 102d may implement a radio technology such as IEEE 802.15 to establish a wireless personal area network (WPAN). In yet another embodiment, the base station 114b and the WTRUs 102c, 102d may utilize a cellular-based RAT (e.g., WCDMA, CDMA2000, GSM, LTE, LTE-A, LTE-A Pro, NR, etc.) to establish a picocell or femtocell. 1A, the base station 114b may have a direct connection to the Internet 110. Thus, the base station 114b may not need to access the Internet through the CN 106.

[0018] The RAN 104 may be in communication with the CN 106, which may be any type of network configured to provide voice, data, application, and / or VoIP services to one or more of the WTRUs 102a, 102b, 102c, 102d. The data may have various quality of service (QoS) requirements, such as different throughput requirements, latency requirements, error tolerance requirements, reliability requirements, data throughput requirements, mobility requirements, etc. The CN 106 may provide call control, billing services, mobile location-based services, prepaid calling, Internet connectivity, video distribution, etc., and / or perform advanced security functions such as user authentication. Although not shown in FIG. 1A , it will be appreciated that the RAN 104 and / or CN 106 may communicate directly or indirectly with other RANs employing the same RAT as the RAN 104 or a different RAT. For example, in addition to being connected to the RAN 104, which may utilize NR radio technology, the CN 106 may also communicate with another RAN (not shown) that employs GSM, UMTS, CDMA2000, WiMAX, E-UTRA, or WiFi radio technology.

[0019] The CN 106 may also serve as a gateway for the WTRUs 102a, 102b, 102c, 102d to access the PSTN 108, the Internet 110, and / or other networks 112. The PSTN 108 may include a circuit-switched telephone network providing plain old telephone service (POTS). The Internet 110 may include a global system of interconnected computer networks and devices that use common communication protocols such as TCP, UDP, and / or IP in the TCP / IP Internet protocol suite. The networks 112 may also include wired and / or wireless communication networks owned and / or operated by other service providers. For example, the network 112 may include another CN connected to one or more RANs that may employ the same RAT as the RAN 104 or a different RAT.

[0020] Some or all of the WTRUs 102a, 102b, 102c, 102d in the communications system 100 may include multi-mode capabilities (e.g., the WTRUs 102a, 102b, 102c, 102d may include multiple transceivers for communicating with different wireless networks over different wireless links.) For example, the WTRU 102c shown in FIG. 1A may be configured to communicate with a base station 114a that may employ cellular-based wireless technology and with a base station 114b that may employ IEEE 802.2 wireless technology.

[0021] 1B is a system diagram illustrating an example WTRU 102. As shown in FIG. 1B, the WTRU 102 may include, among other things, a processor 118, a transceiver 120, a transmit / receive element 122, a speaker / microphone 124, a keypad 126, a display / touchpad 128, non-removable memory 130, removable memory 132, a power source 134, a GPS chipset 136, and / or other peripherals 138. It will be appreciated that the WTRU 102 may include any sub-combination of the foregoing elements while remaining consistent with an embodiment.

[0022] The processor 118 may be a general-purpose processor, a special-purpose processor, a conventional processor, a digital signal processor (DSP), multiple microprocessors, one or more microprocessors in association with a DSP core, a controller, a microcontroller, an application specific integrated circuit (ASIC), a field programmable gate array (FPGA), any other type of integrated circuit (IC), a state machine, etc. The processor 118 may perform signal coding, data processing, power control, input / output processing, and / or any other functionality that enables the WTRU 102 to operate in a wireless environment. The processor 118 may be coupled to the transceiver 120, which may be coupled to the transmit / receive element 122. While FIG. 1B depicts the processor 118 and the transceiver 120 as separate components, it will be appreciated that the processor 118 and the transceiver 120 may be integrated together 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) over the air interface 116. For example, in one embodiment, the transmit / receive element 122 may be an antenna configured to transmit and / or receive RF signals. In an embodiment, the transmit / receive element 122 may be an emitter / detector configured to transmit and / or receive, for example, IR signals, UV signals, 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 light signals. It will be appreciated that the transmit / receive element 122 may be configured to transmit and / or receive any combination of wireless signals.

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

[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 mentioned above, the WTRU 102 may have multi-mode capabilities. Thus, the transceiver 120 may include multiple transceivers to enable the WTRU 102 to communicate via multiple RATs, such as, for example, NR and IEEE 802.11.

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

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

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

[0029] The processor 118 may be further coupled to other peripherals 138, which may include one or more software and / or hardware modules that provide additional features, functions, and / or wired or wireless connectivity. For example, the peripherals 138 may include an accelerometer, an e-compass, a satellite transceiver, a digital camera (for photos and / or videos), a USB port, a vibration device, a television transceiver, a hands-free headset, a Bluetooth module, a frequency modulation (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 peripherals 138 may include one or more sensors. The sensors may be one or more of a gyroscope, an accelerometer, a Hall effect sensor, a magnetometer, a direction 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, a humidity sensor, etc.

[0030] The WTRU 102 may include a full-duplex radio where transmission and reception of some or all of the signals (e.g., associated with a particular subframe for both the UL (e.g., for transmission) and DL (e.g., for reception)) may be parallel and / or simultaneous. The full-duplex radio may include an interference management unit to reduce and / or substantially eliminate self-interference, either through hardware (e.g., a choke) or signal processing via a processor (e.g., a separate processor (not shown) or processor 118). In an embodiment, the WTRU 102 may include a half-duplex radio for transmission and reception of some or all of the signals (e.g., associated with a particular subframe for either the UL (e.g., for transmission) or DL ​​(e.g., for reception)).

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

[0032] The RAN 104 may include eNodeBs 160a, 160b, and 160c, although it will be appreciated that the RAN 104 may include any number of eNodeBs while remaining consistent with an embodiment. The eNodeBs 160a, 160b, and 160c may each include one or more transceivers for communicating with the WTRUs 102a, 102b, and 102c over the air interface 116. In one embodiment, the eNodeBs 160a, 160b, and 160c may implement MIMO technology. Thus, for example, the eNodeB 160a may use multiple antennas to transmit wireless signals to and / or receive wireless signals from the WTRU 102a.

[0033] Each of the eNodeBs 160a, 160b, 160c may be associated with a particular cell (not shown) and may be configured to handle radio resource management decisions, handover decisions, scheduling of users in the UL and / or DL, etc. As shown in FIG. 1C, the eNodeBs 160a, 160b, 160c may communicate with one another via an X2 interface.

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

[0035] The MME 162 may be connected to each of the eNodeBs 160a, 160b, 160c in the RAN 104 via an S1 interface and may function as a control node. For example, the MME 162 may be responsible for authenticating users of the WTRUs 102a, 102b, 102c, bearer activation / deactivation, selecting a particular serving gateway during initial attach of the WTRUs 102a, 102b, 102c, etc. The MME 162 may provide a control plane function for switching between the RAN 104 and other RANs (not shown) that employ other radio technologies such as GSM and / or WCDMA.

[0036] The SGW 164 may be connected to each of the eNodeBs 160a, 160b, 160c in the RAN 104 via an S1 interface. The SGW 164 may generally route and forward user data packets to and from the WTRUs 102a, 102b, 102c. The SGW 164 may perform other functions such as anchoring the user plane during inter-eNodeB handovers, triggering paging when DL data is available to the WTRUs 102a, 102b, 102c, and managing and storing the context of the WTRUs 102a, 102b, 102c.

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

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

[0039] Although the WTRU is depicted in FIGS. 1A-1D as a wireless terminal, in some representative embodiments, it is contemplated that such a terminal may use a wired communication interface (e.g., temporarily or permanently) with the communication network.

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

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

[0042] Using the 802.11ac base mode of operation or a similar mode of operation, an AP can transmit beacons based on a fixed channel, such as a primary channel. The primary channel may be of a fixed width (e.g., a 20 MHz-wide band) or a dynamically configured width. The primary channel may be the operating channel of the BSS and may be used by STAs to establish a connection with the AP. In some representative embodiments, for example, an 802.11 system may implement carrier sense multiple access with collision avoidance (CSMA / CA). With CSMA / CA, STAs (e.g., every STA), including the AP, can sense the primary channel. If the primary channel is sensed / detected and / or determined to be busy by a particular STA, the particular STA may yield. One STA (e.g., only one station) may transmit in a given BSS at any time.

[0043] High-throughput (HT) STAs may use 40 MHz wide channels for communication, for example, by combining a primary 20 MHz channel with adjacent or non-adjacent 20 MHz channels to form a 40 MHz wide channel.

[0044] A very high throughput (VHT) STA may support 20 MHz, 40 MHz, 80 MHz, and / or 160 MHz wide channels. A 40 MHz and / or 80 MHz channel may be formed by combining contiguous 20 MHz channels. A 160 MHz channel may be formed by combining eight contiguous 20 MHz channels or by combining two non-contiguous 80 MHz channels, sometimes referred to as an 80+80 configuration. For the 80+80 configuration, after channel coding, the data may be passed through a segment parser that can split the data into two streams. Inverse fast Fourier transform (IFFT) processing and time-domain processing may be performed separately for each stream. The streams may be mapped onto two 80 MHz channels, and the data may be transmitted by the transmitting STA. At the receiver of the receiving STA, the operations described above for the 80+80 configuration may be reversed, and the combined data may be transmitted to the medium access control (MAC).

[0045] Sub-1 GHz operating modes are supported by 802.11af and 802.11ah. Channel operating bandwidths and carriers are reduced in 802.11af and 802.11ah compared to those used in 802.11n and 802.11ac. 802.11af supports 5 MHz, 10 MHz, and 20 MHz bandwidths in the TV White Space (TVWS) spectrum, while 802.11ah supports 1 MHz, 2 MHz, 4 MHz, 8 MHz, and 16 MHz bandwidths using non-TVWS spectrum. According to a representative embodiment, 802.11ah can support meter-type control / machine-type communication (MTC) devices, such as MTC devices, within macro coverage areas. MTC devices may have limited capabilities, including, for example, support for (e.g., only support for) specific and / or limited bandwidths. MTC devices may include batteries with above-threshold battery life (e.g., to maintain very long battery life).

[0046] WLAN systems that can support multiple channels and channel bandwidths, such as 802.11n, 802.11ac, 802.11af, and 802.11ah, include a channel that may be designated as a primary channel. The primary channel may have a bandwidth equal to the maximum common operating bandwidth supported by all STAs in the BSS. The bandwidth of the primary channel may be set and / or limited by a STA, among all STAs operating in the BSS, that supports the smallest bandwidth operating mode. In an 802.11ah example, the primary channel may be 1 MHz wide for STAs (e.g., MTC-type devices) that support (e.g., only support) the 1 MHz mode, even if the AP and other STAs in the BSS support 2 MHz, 4 MHz, 8 MHz, 16 MHz, and / or other channel bandwidth operating modes. Carrier sensing and / or network allocation vector (NAC) configuration may depend on the status of the primary channel. For example, if the primary channel is busy due to STAs (that only support the 1 MHz mode of operation) transmitting to the AP, all available frequency bands may be considered busy even if most of the available frequency bands remain idle.

[0047] In the United States, the available frequency bands that can be used by 802.11ah are 902 MHz to 928 MHz. In South Korea, the available frequency bands are 917.5 MHz to 923.5 MHz. In Japan, the available frequency bands are 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] 1D is a system diagram illustrating the RAN 104 and the CN 106, according to an embodiment. As described above, the RAN 104 may employ NR radio technology to communicate with the WTRUs 102a, 102b, 102c over the air interface 116. The RAN 104 may also communicate with the CN 106.

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

[0050] The WTRUs 102a, 102b, 102c may communicate with the gNBs 180a, 180b, 180c using transmissions associated with scalable numerology. For example, the OFDM symbol spacing and / or OFDM subcarrier spacing may vary for different transmissions, different cells, and / or different portions of the wireless transmission spectrum. The WTRUs 102a, 102b, 102c may communicate with the gNBs 180a, 180b, 180c using subframes or transmission time intervals (TTIs) of different or scalable lengths (e.g., including different numbers of OFDM symbols and / or continuously varying lengths of absolute time).

[0051] The gNBs 180a, 180b, 180c may be configured to communicate with the WTRUs 102a, 102b, 102c in a standalone configuration and / or a non-standalone configuration. In a standalone configuration, the WTRUs 102a, 102b, 102c may communicate with the gNBs 180a, 180b, 180c without accessing another RAN (e.g., eNodeBs 160a, 160b, 160c). In a standalone configuration, the WTRUs 102a, 102b, 102c may utilize one or more of the gNBs 180a, 180b, 180c as mobility anchor points. In a standalone configuration, the WTRUs 102a, 102b, 102c may communicate with the gNBs 180a, 180b, 180c using signals in unlicensed bands. In a non-standalone configuration, the WTRUs 102a, 102b, 102c may communicate / connect to a gNB 180a, 180b, 180c while also communicating / connecting to another RAN, such as an eNodeB 160a, 160b, 160c. For example, the WTRUs 102a, 102b, 102c may implement a DC principle to communicate with one or more gNBs 180a, 180b, 180c and one or more eNodeBs 160a, 160b, 160c substantially simultaneously. In a non-standalone configuration, the eNodeBs 160a, 160b, 160c may function as mobility anchors for the WTRUs 102a, 102b, 102c, and the gNBs 180a, 180b, 180c may provide additional coverage and / or throughput for serving the WTRUs 102a, 102b, 102c.

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

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

[0054] The AMF 182a, 182b may be connected to one or more of the gNBs 180a, 180b, 180c in the RAN 104 via an N2 interface and may function as a control node. For example, the AMF 182a, 182b may be responsible for user authentication of the WTRUs 102a, 102b, 102c, support for network slicing (e.g., handling various protocol data unit (PDU) sessions with different requirements), selection of a particular SMF 183a, 183b, management of registration areas, termination of non-access stratum (NAS) signaling, mobility management, etc. Network slicing may be used by the AMF 182a, 182b to customize CN support for the WTRUs 102a, 102b, 102c based on the type of service being utilized by the WTRUs 102a, 102b, 102c. For example, different network slices may be established for different use cases, such as services relying on Ultra-Reliable Low-Latency (URLLC) access, services relying on Enhanced High-Capacity Mobile Broadband (eMBB) access, services for MTC access, etc. The AMF 182a, 182b may provide a control plane function for switching between the RAN 104 and other RANs (not shown) that employ other radio technologies such as LTE, LTE-A, LTE-A Pro, and / or non-3GPP access technologies such as WiFi.

[0055] The SMFs 183a, 183b may be connected to the AMFs 182a, 182b in the CN 106 via an N11 interface. The SMFs 183a, 183b may be connected to the UPFs 184a, 184b in the CN 106 via an N4 interface. The SMFs 183a, 183b may select and control the UPFs 184a, 184b and configure the routing of traffic through the UPFs 184a, 184b. The SMFs 183a, 183b may perform other functions such as managing and allocating UE IP addresses, managing PDU sessions, controlling policy enforcement and QoS, providing DL data notification, etc. The PDU session type may be IP-based, non-IP-based, Ethernet-based, etc.

[0056] The UPFs 184a, 184b may be connected to one or more of the gNBs 180a, 180b, 180c in the RAN 104 via an N3 interface, which may provide the WTRUs 102a, 102b, 102c with access to packet-switched networks, such as the Internet 110, to facilitate communication between the WTRUs 102a, 102b, 102c and IP-enabled devices. The UPFs 184a, 184b may perform other functions such as routing and forwarding packets, enforcing user plane policy, supporting multi-homed PDU sessions, handling user plane QoS, buffering DL packets, and providing mobility anchoring.

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

[0058] 1A-1D , and in response to the description of FIGS. 1A-1D , one or more or all of the functions described herein with respect to one or more of the WTRUs 102a-d, base stations 114a-b, eNodeBs 160a-c, MME 162, SGW 164, PGW 166, gNBs 180a-c, AMFs 182a-b, UPFs 184a-b, SMFs 183a-b, DNs 185a-b, and / or any other devices described herein may be performed by one or more emulation devices (not shown). The emulation devices may be one or more devices configured to emulate one or more or all of the functions described herein. For example, the emulation devices may be used to test other devices and / or to simulate the functionality of a network and / or a WTRU.

[0059] The emulation device may be designed to implement one or more tests of other devices within a lab environment and / or a carrier network environment. For example, one or more emulation devices may perform one or more or all functions while fully or partially implemented and / or deployed as part of a wired and / or wireless communications network to test other devices within the communications network. One or more emulation devices may perform one or more or all functions while temporarily implemented / deployed as part of a wired and / or wireless communications network. The emulation device may be directly coupled to another device for purposes of testing and / or performing tests using over-the-air wireless communications.

[0060] The one or more emulation devices may perform one or more functions, inclusive, while not being implemented / deployed as part of a wired and / or wireless communication network. For example, the emulation devices may be utilized in a test lab and / or in a test scenario within an undeployed (e.g., testing) wired and / or wireless communication network to implement testing of one or more components. The one or more emulation devices may be test equipment. Direct RF coupling and / or wireless communication via RF circuitry (which may, for example, include one or more antennas) may be used by the emulation devices to transmit and / or receive data.

[0061] A WLAN in infrastructure basic service set (BSS) mode has an access point (AP) for the BSS and one or more stations (STAs) associated with the AP. The AP typically has access or interface to a distribution system (DS) or another type of wired / wireless network that carries traffic within and outside the BSS. Traffic to a STA originating from outside the BSS arrives through the AP and is delivered to the STA. Traffic originating from a STA destined for a destination outside the BSS is sent to the AP for delivery to the respective destination. Traffic between STAs within the BSS may also be sent through the AP, with the source STA sending traffic to the AP, and the AP delivering the traffic to the destination STA. Such traffic between STAs within the BSS is actually peer-to-peer traffic. Such peer-to-peer traffic may also be sent directly between the source and destination STAs using direct link setup (DLS) using 802.11e DLS or 802.11z tunneled DLS (TDLS). A WLAN using independent BSS (IBSS) mode does not have an AP and / or has STAs that communicate directly with each other. This communication mode is called an "ad hoc" communication mode.

[0062] Using the 802.11ac infrastructure mode of operation, an AP can transmit beacons on a fixed channel, usually the primary channel. This channel may be 20 MHz wide and is the operating channel of the BSS. This channel is also used by STAs to establish connections with the AP. The basic channel access mechanism in 802.11 systems is Carrier Sense Multiple Access with Collision Avoidance (CSMA / CA). In this mode of operation, all STAs, including the AP, sense the primary channel. If the channel is detected as busy, the STA yields. Therefore, only one STA can transmit at any time within a given BSS.

[0063] 802.11n also allows high-throughput (HT) STAs to use 40 MHz wide channels for communication, which is achieved by combining a primary 20 MHz channel with adjacent 20 MHz channels to form a 40 MHz wide contiguous channel.

[0064] In 802.11ac, very high throughput (VHT) STAs can support channels of 20 MHz, 40 MHz, 80 MHz, and / or 160 MHz width. 40 MHz and 80 MHz channels are formed by combining contiguous 20 MHz channels, similar to 802.11n described above. A 160 MHz channel may be formed by combining eight contiguous 20 MHz channels or two non-contiguous 80 MHz channels, sometimes referred to as an 80+80 configuration. In the 80+80 configuration, after channel coding, the data is passed through a segment parser that splits the data into two streams. IFFT and time-domain processing are performed separately for each stream. The streams are then mapped onto two channels, and the data is transmitted. At the receiver, this mechanism is reversed, and the combined data is transmitted to the MAC.

[0065] Sub-1 GHz operating modes are supported by 802.11af and 802.11ah. These specifications use reduced channel operating bandwidths and carriers 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, while 802.11ah supports 1 MHz, 2 MHz, 4 MHz, 8 MHz, and 16 MHz bandwidths using non-TVWS spectrum. A potential use case for 802.11ah is support for meter-type control (MTC) devices within macro coverage areas. MTC devices have limited capabilities, including support for limited bandwidths, but may also have requirements for very long battery life.

[0066] WLAN systems that support multiple channels and channel widths, such as 802.11n, 802.11ac, 802.11af, and 802.11ah, include a channel designated as the primary channel. The primary channel may, but need not, have a bandwidth equal to the maximum common operating bandwidth supported by all STAs in the BSS. The bandwidth of the primary channel is therefore limited by the STA that supports the smallest bandwidth operating mode among all STAs operating in the BSS. In the example of 802.11ah, even if the AP and other STAs in the BSS can support 2 MHz, 4 MHz, 8 MHz, 16 MHz, or other channel bandwidth operating modes, the primary channel may be 1 MHz wide if there are STAs (e.g., MTC-type devices) that support only the 1 MHz mode. All carrier sensing and NAV setting depend on the status of the primary channel; i.e., if the primary channel is busy, for example, because STAs that only support the 1 MHz operating mode are transmitting to the AP, the entire available frequency band is considered busy, even if most of it remains idle and available.

[0067] In the United States, the available frequency bands that can be used by 802.11ah are 902 MHz to 928 MHz. In South Korea, it is 917.5 MHz to 923.5 MHz, and in Japan, it 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.

[0068] IEEE 802.11 High Efficiency WLAN (HEW) can enhance the quality of service experienced by all users over a wide spectrum of wireless users in many usage scenarios, including high-density scenarios in the 2.4 GHz, 5 GHz, and 6 GHz bands. New use cases that support high-density deployment of APs and STAs and associated radio resource management (RRM) technologies are considered with HEW.

[0069] Potential applications for HEW may include emerging usage scenarios such as data distribution for stadium events, high user density scenarios such as train stations, or business / retail environments, and evidence of an increasing reliance on video distribution and wireless services for medical applications.

[0070] In IEEE 802.11ax, some embodiments have shown that the traffic measured for various applications has a high probability of short packets, and that there are network applications that can also generate short packets, including the following applications: Virtual Office, TCP ACK, Video Streaming ACK, Device / Controller (mouse, keyboard, game control, etc.), Access-Probe Request / Response, Network Selection-Probe Request, ANQP, and Network Management-Control frames.

[0071] Also, many embodiments in 802.11ax describe the introduction of MU features, including UL and DL OFDMA and UL and DL MU-MIMO. Designing and defining mechanisms for multiplexing UL random access for various purposes may be considered in this disclosure.

[0072] In IEEE 802.11ax, medium access in the 6 GHz band may include several embodiments. One embodiment may use triggered or scheduled medium access in the 6 GHz band. Another embodiment may use limited active scanning and may have scheduled EDCA medium access in the 6 GHz band.

[0073] Hybrid Automatic Repeat Request (HARQ) has become the primary transmission error control technique in wireless communication networks, relying on a combination of error correction codes and retransmissions. HARQ has been adopted in wireless communication standards such as 3GPP's UMTS, LTE, and IEEE 802.16 WiMax.

[0074] Two popular types of HARQ combining schemes exist in the technical literature: Tracking Combining (CC) HARQ and Incremental Redundancy (IR) HARQ.

[0075] In a tracking combining HARQ scheme, each retransmission contains the same data and parity bits. The receiver combines the received packet with the previous transmission using maximal ratio combining (MRC). Tracking combining can be viewed as repetition coding, where each retransmission increases Eb / N0 at the receiver.

[0076] For incremental redundancy HARQ schemes, each retransmission uses a different set of coded bits (e.g., different redundancy versions generated by puncturing the encoder output). For turbo codes, this means different systematic and parity bits. With each retransmission, the receiver obtains additional information. Variations of IR HARQ exist: the retransmission includes parity bits or is self-decodable.

[0077] In general, HARQ schemes can be classified as either synchronous or asynchronous, and retransmissions in each case can be either adaptive or non-adaptive. In the case of synchronous HARQ, retransmissions per process occur at predefined times relative to the initial transmission. Therefore, there is no need to signal the HARQ process ID, which can be inferred from the retransmission timing. On the other hand, in the case of asynchronous HARQ, retransmissions can occur at any time relative to the initial transmission. Therefore, explicit signaling is required to indicate the HARQ process ID and ensure that the receiver can correctly associate each retransmission with the corresponding previous transmission.

[0078] In LTE, the HARQ entity is located in the MAC layer and is responsible for transmit and receive HARQ operations. Transmit HARQ operations include the transmission and retransmission of transport blocks and the reception and processing of ACK / NACK signaling. Receive HARQ operations include receiving transport blocks, combining the received data, and generating ACK / NACK signaling based on the decoding results. To allow continuous transmission while the previous transport block is being decoded, up to eight parallel HARQ processes are used to support multi-process "stop and wait" (SAW) HARQ operations. Multi-process HARQ thus interlaces several independent SAW processes in time, so that all transmission resources can be used by one of the processes. Each HARQ process is responsible for a separate SAW operation and manages a separate buffer.

[0079] The LTE standard uses asynchronous adaptive HARQ in the downlink and synchronous HARQ (which can be either adaptive or non-adaptive) in the uplink.

[0080] In LTE, the following signaling may be used to support HARQ: HARQ process ID (for asynchronous HARQ only), New Data Indicator (NDI) (triggered whenever a new packet transmission begins), Redundancy Version (RV) (RV of the transmission block (for adaptive HARQ only)), and / or MCS (for adaptive HARQ only).

[0081] In 3GPP NR, the following HARQ features may be supported: multiple HARQ processes, dynamic and semi-static HARQ ACK codebooks, CBG-level HARQ retransmissions, asynchronous and adaptive HARQ, and flexible timing between data transmission and HARQ ACK feedback.

[0082] In 3GPP NR, codeword block group (CBG)-level HARQ retransmissions are supported. A transmission block (TB) may contain one or more CBGs, and CBGs may have their own HARQ ACK bits. Therefore, it is possible for the transmitter to retransmit a partial TB. Two CBG-related signaling fields, CBG Transmission Information (CBGTI) and CBG Flush-Out Information (CBGFI), are carried by the DCI. The CBGTI indicates the CBG that the (re)transmission carries. A CBGFI set to '0' indicates that an earlier received instance of the same CBG being transmitted may have been corrupted, and a CBGFI set to '1' indicates that the retransmitted CBG can be combined with an earlier received instance of the same CBG.

[0083] In 3GPP Unlicensed NR (NR-U), HARQ feedback may be transmitted over unlicensed bands. NR-U may consider mechanisms to support flexible triggering and multiplexing of HARQ feedback for one or more DL HARQ processes. The following techniques are identified as beneficial for NR-U transmission: (1) techniques to handle reduced HARQ A / N transmission opportunities for a given HARQ process due to LBT failure, and (2) transmission of HARQ A / Ns for corresponding data within the same shared channel occupancy time (COT). For the first technique, potential techniques may include mechanisms to provide multiple and / or complementary time- and / or frequency-domain transmission opportunities. For the second technique, it is understood that in some cases, HARQ Ack / Nacks may need to be transmitted within a COT separate from the COT in which the corresponding data was transmitted. A mechanism to support this needs to be identified.

[0084] IEEE 802.11 Extreme High Throughput (EHT) may be the next major revision of the IEEE 802.11 standard following 802.11ax. EHT is designed to explore the possibility of further increasing peak throughput and improve the efficiency of IEEE 802.11 networks. Key use cases and addressed applications may include high-throughput and low-latency applications such as video over WLAN, augmented reality (AR), and virtual reality (VR).

[0085] The list of features within the EHT that achieve the goals of increased peak throughput and improved efficiency may include, but is not limited to, multi-AP, multi-band, z-bandwidth, 16 partial streams, HARQ, full duplex (in time and frequency domain), AP coordination, semi-orthogonal multiple access (SOMA), and new designs for 6 GHz channel access.

[0086] Collision-aware HARQ for EHT is described herein.

[0087] Figure 2 shows exemplary hybrid automatic repeat request (HARQ) goodput performance with collisions. In unlicensed channels, the noise model may be collision-dominant with interference from other 802.11 transmitters as well as other radio access technologies (e.g., 3GPP unlicensed NR). In the case of failed transmissions due to increased interference, possibly non-Gaussian, utilizing these transmissions for HARQ combining may result in worse performance than simple ARQ.

[0088] As shown in Figure 2, using incremental redundancy (IR) HARQ in the presence of collisions results in performance degradation at higher SNRs. Embodiments that do not degrade performance may include restricting HARQ to collision-free environments, e.g., trigger-based transmissions or multi-AP deployments, or using modified receivers that incorporate the presence of collisions.

[0089] 3 shows an example of a collision-aware HARQ receiver. As shown in FIG. 3, the collision-aware HARQ receiver can be used in the following procedure: (1) receive Rx packet at 301, (2) decode Rx packet at 302, (3) if unsuccessful, add HARQ buffer at 303, then decode at 304, (3) if unsuccessful, find if there was a collision at 305, (4) if there was a collision, discard at 306, if there was no collision, add to buffer at 307. FIG. 4 shows exemplary performance of the collision-aware HARQ receiver shown in FIG. 3. This results in improved performance as seen in IR Rx, but assumes an ideal collision estimator.

[0090] IEEE 802.11ax has recently expanded its scope to include operation of 802.11ax devices in the 6 GHz band, which is expected to be open to unlicensed use. Because there are no legacy WLAN devices operating in the 6 GHz band, backward compatibility requirements are not expected to be very stringent. Given this potential new medium access paradigm, there is a need for HARQ medium access and scheduling, as well as HARQ transmission protocols for the 6 GHz band.

[0091] One of the features that HARQ technology can provide is range extension. To provide range extension, HARQ transmissions may need to exceed the minimum MCS currently used in WLANs. However, any HARQ transmissions must rely on current WLAN signaling and waveform designs, which are still subject to the minimum MCS associated with the current longest range. To provide extended range, a HARQ transmission protocol and additional signaling design are needed that enable HARQ transmissions over longer ranges.

[0092] Collision-aware HARQ schemes may require the receiver or transmitter to know that a collision has occurred and be able to modify its behavior. For example, a sudden power level change in the received signal strength indicator / received channel power indicator (RSSI / RCPI) during the reception process can indicate the occurrence of a collision, but in a fading channel, this may be an unreliable method. Therefore, signaling, feedback, and procedures are required that allow the EHT transmitter and receiver to reliably indicate the occurrence of a collision.

[0093] Embodiments of HARQ scheduling and medium access for the 6 GHz band are described herein.

[0094] Embodiments are described herein for WLAN medium access and / or time division duplex (TDD) medium access systems within the 6 GHz band.

[0095] The beacon interval may have a fixed format or a pre-configured / pre-defined format so that any STA that may miss the beacon frame may have an opportunity to find out the timing information and be able to communicate with the AP.

[0096] An embodiment that allows a STA to communicate with an AP when it may miss a beacon frame (e.g., the STA may switch APs or bands mid-beacon interval) may include: (1) a fixed beacon interval format: fixed beacon frame size, fixed TDD interval size; (2) a TDD ID within each TDD interval; (3) a special sequence at the beginning of each TDD interval or a longer preamble in the first transmission of the TDD; and (4) TDD identification information within each TDD interval that indicates which TDD it may be.

[0097] Figure 5 shows three example beacon intervals having time division duplex (TDD) intervals. In one example, the beacon intervals may be made up of TDD intervals as shown in Figure 5. Beacon interval 501 is a first example of a beacon interval having a TDD interval. Beacon intervals 502 and 503 are two other examples of beacon intervals having a TDD interval.

[0098] A TDD interval may have a fixed size. Each TDD interval may be used to transmit one or more frames from one or more STAs. For example, DL TDD may be initiated by an AP. Once the AP acquires the channel via EDMA / CA, it can then share it with one or more STAs. STAs may transmit within the interval with limited channel sensing. A DL TDD interval may be used for multiple DL / UL frame exchanges.

[0099] Various TDD intervals may be defined, and various TDD intervals may have different transmission / medium evaluation rules. Examples of TDD intervals may include, but are not limited to, a beacon TDD interval, a DL TDD interval, an UL TDD interval, and a special TDD interval.

[0100] The beacon TDD interval may be located at the beginning of a beacon interval. The beacon TDD interval may be used to transmit one or more beacon frames. In one example, the beacon TDD interval may occur once within a beacon interval. In another example, the beacon TDD interval may occur optionally within a beacon interval, resulting in beacon frame transmission being skipped. The beacon TDD interval size may be predefined with a fixed duration. In one example, the beacon TDD interval size may be configurable. For example, beacon TDD intervals of types 1 to N may be predefined with N sizes. A type 1 beacon TDD interval may be capable of carrying a complete beacon frame with all management elements. A type 2 beacon TDD interval may be capable of carrying a beacon frame with information for most of the elements. A type N beacon TDD interval may carry a beacon frame with basic information and a minimum size. The beacon TDD interval type may be announced in advance via a previous beacon frame or in another band. If the transmission of a beacon frame may cross the boundary of the beacon TDD interval, the beacon frame may be truncated and the truncated portion may be transmitted during a later beacon interval. If the transmission of a beacon frame may be shorter than the beacon TDD interval, the AP may have several options, which may be pre-configured or announced by the AP in the beacon frame: (1) the AP may enable other STAs to transmit in the remainder of the beacon TDD interval using EDMA / CA, (2) the AP may not enable other STAs to transmit in the remainder of the beacon TDD interval. The AP may transmit special control / management signals or training / sounding signals. The AP may not enable other STAs to transmit, or (3) the AP may not transmit either, in which case the medium may not be used by STAs in the BSS, and as a result, that period may be used to measure inter-BSS interference.

[0101] A DL TDD interval may be used to exchange data / control / management information between the AP and STAs. A DL TDD interval may be initiated by the AP, once which acquires the channel via EDMA / CA and can share it with one or more STAs. STAs may transmit within the interval with limited or no channel sensing. In one example, all DL TDD intervals within a beacon interval may have the same fixed size. That size may be predefined or preconfigured. If configured, the DL TDD interval size may be conveyed in the beacon frame and / or other control / management frames transmitted in-band or out-of-band.

[0102] The UL TDD interval may be used to exchange data / control / management information between the AP and the STAs. In one example, all UL TDD intervals within a beacon interval may have the same fixed size. The size may be predefined or preconfigured. If configured, the UL TDD interval size may be carried in the beacon frame and / or other control / management frames transmitted in-band or out-of-band. STAs that may have uplink traffic to transmit can closely monitor the UL TDD interval. The channel access procedure for the UL TDD interval may follow one or more of the following examples.

[0103] First, the UL TDD interval may be initiated by the AP. Once the AP acquires the channel via EDMA / CA or scheduling, it can transmit a trigger frame to trigger simultaneous UL transmissions. The trigger frame may be used to trigger dedicated or random STAs. The AP can share it with one or more STAs. STAs can transmit within the interval with limited or no channel sensing.

[0104] Second, the UL TDD interval may be initiated by the STA. Once the STA acquires the channel via EDMA / CA or scheduling, it can transmit uplink frames to the AP. The AP then shares the TDD and can transmit to the STA and other STAs.

[0105] Special TDD intervals may have special formats for special uses. Examples of special TDD intervals may include, but are not limited to, target wake time (TWT) TDD, restricted access window (RAW), power saving TDD, and training TDD.

[0106] In the case of TWT TDD, the intervals may use conventional TWT transmission procedures.

[0107] In the case of RAW TDD, the interval can use conventional RAW transmission procedures.

[0108] In the case of power-saving TDD, the interval may be used to wake up STAs in power-saving mode.

[0109] For training TDD, the intervals may be used for one-to-one or one-to-many sounding, beamforming training.

[0110] FIG. 5 shows some examples of proposed beacon intervals for TDD systems.

[0111] At the end of a TDD interval, a transmission may have to be truncated so as not to cross a TDD boundary. If a transmission completes before the end of TDD, either (1) the AP can enable other STAs to transmit using EDMA / CA, (2) the AP cannot enable other STAs to transmit and can transmit special control / management signals or training / sounding signals, or (3) the AP cannot enable other STAs to transmit and can transmit neither. In this third case, the medium may not be used by STAs in the BSS, and as a result, the period may be used to measure inter-BSS interference.

[0112] Embodiments for TDD index and identification information and sequences are described herein.

[0113] Figure 6 shows an example detailed TDD interval structure. In one example, each TDD may carry a TDD index and / or TDD identification information and / or sequence, as shown in Figure 6. As shown in Figure 6, a beacon interval may comprise a beacon 601 and multiple TDDs (i.e., TDD 1, TDD 2, ..., TDD N).

[0114] The TDD index may be used by the STA to determine timing information and when the next beacon can be expected. In one example, the TDD index may be explicitly conveyed. For example, the TDD index may be conveyed in a Physical Layer Convergence Protocol (PLCP) header or a MAC header. The TDD index may be explicitly conveyed in the first transmission in a TDD interval or in every frame in a TDD interval. In one example, the number of TDDs in a beacon interval may be a fixed number so that the STA knows the expected time for the next beacon frame. In one example, the TDD index may be transmitted in a countdown manner, so that the index can indicate the number of TDDs remaining in the beacon interval.

[0115] Since different TDDs may have different channel access procedures and TDD formats, the TDD identification information may be used to indicate what kind of TDD it may be. For example, the TDD identification information may indicate whether the TDD is a DL TDD, an UL TDD, a specialized TDD (and which specialized TDD), etc.

[0116] A TDD sequence may be transmitted at the beginning of each TDD interval, and STAs can detect the start of TDD by looking for the TDD sequence.

[0117] A TDD schedule element may be defined and carried within a beacon frame. The TDD schedule element may indicate a beacon interval duration, a number of TDDs within a beacon interval, TDD identification information, or TDD-specific information. The beacon interval duration may indicate the duration of the current beacon interval. The duration may be predefined or preconfigured. The TDD identification information or TDD-specific information field may be used to indicate TDD identification information for each TDD. In one example, the TDD schedule element may be used to schedule a TDD interval structure for one or more beacon intervals. In another example, the number of valid beacon intervals may be indicated. The number of valid beacon intervals may indicate that the same TDD interval format may be valid for these number of beacon intervals.

[0118] Embodiments for out-of-band scheduling are described herein.

[0119] An AP or a collocated AP may be able to operate on multiple bands. An AP in Band 1 may configure transmissions for APs in Band 2. For example, Band 1 may be a 5 GHz band where traditional EDMA / CA channel access procedures may apply, while Band 2 may be a 6 GHz band where limited EDMA / CA may apply. For example, only the AP may need to perform EDMA / CA for channel access, and transmissions from STAs may be more scheduled.

[0120] In one example, Band 1 may contain information that helps STAs associate or re-associate with an AP in Band 2. For example, TDD schedule elements may be carried and transmitted in Band 1. Medium access on Band 2 may be different than that in Band 1. Thus, some medium access information may be carried in Band 1.

[0121] In one example, band 1 may carry some management and control signaling intended for band 2. Because transmissions on band 2 may carry fewer management and control signals, it may carry more data transmissions. For example, band 2 may carry limited beacons (i.e., the beacons may carry less information than conventional beacons). The beacon interval may be larger than in conventional WiFi systems.

[0122] Embodiments for HARQ scheduling are described herein.

[0123] HARQ transmissions spanning multiple TDD intervals may be possible. Moreover, the transmission may be at the end of a TDD interval, so that the acknowledgement may be transmitted within the same interval.

[0124] FIG. 7 illustrates an exemplary procedure for HARQ across a TDD boundary. STA (STA1) may transmit a frame to STA (STA2) at the end of a TDD interval. In one example, STA2 may be an AP, and the transmission may be a triggered uplink transmission. The STA may not expect to receive a return acknowledgment within the same TDD. The STA may set a HARQ policy (indicated by data 701) to indicate an acknowledgment, with possible retransmissions within a later TDD (i.e., TDD 2). The HARQ policy may be carried within the MAC header. As shown in FIG. 7, NAK 702 may be polled, and data Rx 703 may indicate that a retransmission may be triggered by the NAK. ACK 704 may indicate that data 701 in TDD 1 was successfully received. Alternatively or additionally, the above HARQ policy may be carried within the PLCP header. Both STA1 and STA2 may keep transmitted and received packets in HARQ buffers.

[0125] STA2 may have an opportunity to transmit in a future TDD, for example, TDD 2. STA2 can send a BA request frame to STA1.

[0126] Depending on the reception result, STA1 can send a positive or negative acknowledgement (ACK or NAK) to STA2. In case of a NAK, the HARQ policy can indicate whether a retransmission can be triggered immediately after the acknowledgement or a delay, or in a future TDD.

[0127] STA2 is able to follow instructions.

[0128] Embodiments for HARQ range extension are described herein. Embodiments for extended range beacons and waveforms are also described herein.

[0129] An embodiment for post-association HARQ range extension is described as follows.

[0130] As described above, HARQ techniques may be used in WLAN scenarios to provide range extension. However, under currently known WLAN signaling and waveform designs, the range of HARQ transmissions is limited. To provide an extended range, the present application discloses a method and a WTRU that use a new HARQ transmission protocol and signaling design that can enable HARQ transmissions over a longer range. The method and WTRU according to the present application use a slow range extension (LRRE) HARQ PPDU for transmissions between the WTRU and the AP in an LRRE HARQ scheme. In the present application, unless otherwise indicated, the terms “LRRE HARQ scheme,” “LRRE HARQ mode,” and “LRRE HARQ operation” may be used interchangeably. It should be noted that the LRRE HARQ scheme according to the present application is used in a WLAN scenario, and therefore the term “LRRE HARQ operation” can refer to either the operation of the WLAN (i.e., WLAN connection) or the operation of a station (e.g., a WTRU or an AP). It should be noted that in this application, unless otherwise indicated, the terms "extended range," "range extension," and "LRRE" may be used interchangeably.

[0131] The method and WTRU according to the present application can provide range extension using an LRRE HARQ scheme, which may support a WTRU even when it is beyond the range of its supported MCS or when its transmission rate is lower than a non-HARQ MCS. A method, WTRU, and AP using the LRRE HARQ scheme to provide extended range for a WLAN is described below with reference to Figures 8A-8D.

[0132] A first embodiment according to the present application will be described with reference to Fig. 8A. Fig. 8A shows an exemplary flowchart of a method 800 according to the first embodiment of the present application. It should be noted that the method 800 shown in Fig. 8A may be used by a WTRU according to the present application.

[0133] 8A , the method 800 includes receiving LRRE information from an AP at 801, determining whether a first condition is met by the WTRU at 802, sending a mode change request to the AP to change the operation mode to the LRRE HARQ mode on the condition that the first condition is met at 803, receiving a response regarding the mode change request from the AP at 804, and communicating with the AP using a plurality of physical layer convergence procedure (PLCP) protocol data units (PPDUs) at 805. Each of the plurality of PPDUs may comprise (1) at least one field that enables transmission between the WTRU and the AP under the first condition, and / or (2) an LRRE HARQ mode indication.

[0134] Accordingly, a WTRU providing range extension for a WLAN according to the present application may comprise a receiver configured to receive LRRE information from an AP, a transmitter, and a processor configured to determine whether a first condition is met by the WTRU, wherein, on condition that the first condition is met, the transmitter is further configured to send a mode change request to the AP to change the operating mode to the LRRE HARQ mode, and the receiver is further configured to receive a response regarding the mode change request from the AP, and the WTRU is configured to communicate with the AP using a plurality of PPDUs, each of the PPDUs comprising (1) at least one field that enables transmission between the WTRU and the AP under the first condition, and (2) an LRRE HARQ mode indication.

[0135] The processes in the method 800 and the components within the WTRU are described in detail below with reference to specific embodiments.

[0136] 8A, the method 800 may include receiving LRRE information from an AP, at 801. In response, the receiver is configured to receive the LRRE information from the AP.

[0137] In an embodiment, the LRRE information may include LRRE capability information, which may indicate the capability of the AP to operate in the LRRE mode of operation.

[0138] For example, the LRRE capability information may include a distance parameter indicating the distance range within which an AP can operate in the LRRE mode of operation, ie, the distance range within which the AP's signal can be received by a WTRU in the LRRE mode of operation.

[0139] As another example, the LRRE capability information may include a speed parameter indicating the speed range in which the AP can operate in the LRRE operating mode, i.e., the speed range in which the AP's signal can be received by a WTRU located within a desired distance in the LRRE operating mode.

[0140] The LRRE information may also include LRRE support information, which may indicate under what conditions an AP can support LRRE operation, i.e., under what conditions an AP can communicate with a WTRU in an LRRE operation mode.

[0141] The LRRE information may also include HARQ capability information. For example, the LRRE information may include the capability of the AP to transmit data information using the HARQ scheme in the LRRE operation mode, i.e., the capability of the AP to transmit using the LRRE HARQ scheme.

[0142] It will be appreciated that the above examples are not intended to be exclusive or limiting to the present application. The LRRE information received in 801 may be other information as long as the information can be useful in realizing the principles of the present application.

[0143] Preferably, before receiving the LRRE information from the AP, the method 800 may further include associating the WTRU with the AP. Accordingly, the WTRU may associate with the AP before the receiver receives the LRRE information from the AP.

[0144] As described above, method 800 may be used to provide extended range after a WTRU associates with an AP. In an embodiment, the WTRU may associate with the AP using a series of request-response procedures including authentication and association. It should be appreciated that the association method used by the WTRU and according to the present application may be any known or further developed association process. In other words, the WTRU may associate with the AP using any available method as long as the method can serve to realize the principles of the present application.

[0145] Preferably, method 800 may also include exchanging the above-described LRRE information between the WTRU and the AP after the WTRU associates with the AP. More specifically, when the WTRU associates with the AP, it can exchange its capabilities regarding slow switching range and / or HARQ capability support with the AP. On the one hand, the WTRU can transmit its LRRE information and / or HARQ capability information to the AP, and on the other hand, the AP can also transmit its LRRE information to the WTRU. Thus, both the WTRU and the AP know each other's LRRE information, and therefore, they can change their operation mode to LRRE operation based on the LRRE information from each other under certain circumstances, such as when a first condition (described below) is met.

[0146] It will be appreciated that generally speaking, a WTRU (e.g., WTRU 102a shown in FIG. 1) and an AP may be referred to as a station. For example, in a WLAN scenario, a wireless access point (WAP) may be referred to as a station (i.e., an AP station), and a laptop or smartphone may also be referred to as a station (i.e., a non-AP station). In this application, for clarity, an AP station will be referred to as an AP, and a non-AP station will be referred to as a WTRU.

[0147] The method 800 may then proceed to process 802. At 802, the method 800 may include determining whether a first condition is met by the WTRU. In response, the processor may determine whether the first condition is met by the WTRU.

[0148] In an embodiment, the first condition may be met when the channel quality of the channel used by the WTRU is less than the channel quality value. In other words, the first condition is that the channel quality of the channel used by the WTRU is less than the channel quality value. In this application, the channel quality value may also be referred to as the second value to distinguish between values ​​for various conditions that may be used for the method according to the application.

[0149] Channel quality may be affected by many different factors, such as distance and interference. For example, generally, the longer the distance between the WTRU and the AP, the worse the channel quality. The more networks operating on the same channel, the more interference each encounters, causing frequent disconnections and packet loss on connected client devices. Channel quality may be defined by various parameters, such as packet loss rate, latency, jitter, signal strength, etc. For example, channel quality may be defined by packet loss rate. If the packet loss rate increases, the channel quality will be worse, and if the packet loss rate decreases, the channel quality will be better.

[0150] Therefore, the second value may be the value of one of the above-mentioned parameters. For example, if the channel quality is defined by a packet loss rate, the second value may be 5%. If the channel quality is defined by a latency, the second value may be 3 ms.

[0151] Although some examples of channel quality and second values ​​are given above, it should be appreciated that they are not intended to be exclusive or limiting to the present application. The channel quality and first value may alternatively be determined or defined by other available methods in accordance with the principles of the present application.

[0152] In another embodiment, the first condition is met when the current distance between the WTRU and the AP is greater than the distance value. In other words, the first condition is that the current distance between the WTRU and the AP is less than the distance value. In this application, the distance value may also be referred to as the first value to distinguish between values ​​for various conditions.

[0153] Generally, the longer the distance between a WTRU and an AP, the more difficult it becomes for them to communicate with each other. The current distance may not be a constant value because the WTRU may be moved by its user. At times, the WTRU may be far from the AP, and the distance between the WTRU and the AP will continue to increase, causing the signal strength from the AP to continue to decrease. If the distance becomes too large (e.g., greater than a threshold distance value), the signal from the AP may be too weak to reach the WTRU. One of the objectives of this application is to provide range extension of the connection (e.g., WLAN connection) between a WTRU and an AP, so that even if the WTRU is some distance away from the AP (e.g., even if the current distance is greater than a threshold distance value), they can still communicate with each other.

[0154] Preferably, the process at 802 may be executed by the WTRU at regular time intervals, such as every 3 seconds. By executing the process at 802 at regular time intervals, the WTRU can detect changes in distance in a timely manner, so that the WTRU can initiate those processes (e.g., those processes following the process at 802) to maintain its communication with the AP when the current distance is greater than a threshold distance value.

[0155] The current distance may be detected by transmitting an UL frame and / or a DL frame between the WTRU and the AP and determining parameters in the frame that indicate the transmission time and reception time. Note that the distance detection methods described above are only provided as examples and are not intended to be exclusive or limiting to the present application. The method 800 according to the present application and the WTRU may use any other available and suitable methods to detect the current distance between the WTRU and the AP, as long as those methods can help realize the principles of the present application.

[0156] The above description describes some examples of first conditions, which are not intended to be exclusive or limiting to the first conditions that may be applied in the present application. The first conditions determined by the WTRU in 802 may be any other conditions as long as they can help realize the principles of the present application.

[0157] Next, method 800 may proceed at 803. At 803, method 800 may include sending a mode change request to the AP to change the operating mode to the LRRE HARQ mode. In response, the transmitter may send a mode change request to the AP to change the operating mode to the LRRE HARQ mode.

[0158] In an embodiment, the operating mode may represent a current operating mode of a WLAN. In another embodiment, the operating mode may represent a current operating mode of an AP or a current operating mode of a WTRU. For example, before a station (e.g., a WTRU or an AP) switches to the LRRE HARQ mode, it may be operating in a base operating mode (e.g., the WTRU connects to the AP via a wireless link) or a default mode (e.g., the WTRU communicates with the AP using a non-LRRE HARQ mode). It should be appreciated that the above examples of current operating modes are not intended to be limiting on the current operating modes in which the WLAN, WTRU, and / or AP may be operating. Any other available and suitable operating mode may be the current operating mode as long as the current operating mode can be useful for implementing the principles of the present application.

[0159] The LRRE HARQ mode may indicate that a station (e.g., a WTRU) is communicating with another station (e.g., an AP) using the LRRE HARQ scheme. Accordingly, in the LRRE HARQ mode, the WTRU may transmit and receive PPDUs (e.g., LRRE HARQ PPDUs) by using the LRRE HARQ scheme. Accordingly, the AP may transmit and receive PPDUs (e.g., LRRE HARQ PPDUs) by using the LRRE HARQ scheme. In this application, unless otherwise indicated, the terms “LRRE HARQ mode,” “HARQ mode,” “LRRE HARQ scheme,” and “LRRE operation mode” may be used interchangeably. The following description further illustrates the LRRE HARQ scheme and the LRRE HARQ PPDU with reference to detailed embodiments.

[0160] The purpose of sending the mode change request is to request a switch from the current operating mode to the LRRE HARQ mode. The mode change request may be an HARQ request frame. In an embodiment, the HARQ request frame may be a separate frame transmitted separately from the WTRU to the AP. In another embodiment, the HARQ request frame may be part of another frame (e.g., a trigger frame, an UL data frame, etc.) transmitted by the WTRU. Although several examples of HARQ request frames are given above, it will be appreciated that they are not intended to be exclusive or limiting to the present application. The HARQ request frame may be implemented by any other available frame as long as those other available frames can help realize the principles of the present application. It will also be appreciated that a mode change request may be sent by the AP to the WTRU if the AP initiates a mode change. The following description further describes various scenarios for transmitting and receiving a mode change request.

[0161] In an embodiment, the mode change request may include a HARQ request. That is, the HARQ request may be part of the mode change request. The HARQ request may indicate that the transmitter (e.g., a WTRU) sending the mode change request is attempting to initiate communication via a HARQ scheme. Thus, the HARQ request is essentially similar to those well-known HARQ requests sent by a WTRU during data transmission (e.g., UL data transmission from the WTRU to an AP). After receiving this HARQ request, the receiver (e.g., an AP) may send a response regarding the HARQ request back to the transmitter. The following description further describes this request-response process in detail.

[0162] In another embodiment, the mode change request may indicate a HARQ operation type. For example, the mode change request may include the exact type of HARQ operation it is requesting. In the method 800 and WTRU according to the present application, the mode change request may include LRRE as the type of HARQ operation. It should be noted that although the present application has described the method 800 and WTRU for providing WLAN range extension based on an LRRE HARQ scheme, the principles of the present application may also be implemented with other HARQ operation types, such as Tracking Combining (CC) and Incremental Redundancy (IR).

[0163] In another embodiment, the mode change request may indicate a HARQ process mode. For example, the mode change request may include detailed HARQ process modes such as OFDMA HARQ, multiple stop and waits, the number of parallel HARQ processes, etc. The HARQ process modes described above are not intended to be exclusive or limiting to the present application. The mode change request may include other detailed HARQ process modes as long as these modes can help realize the principles of the present application.

[0164] In an embodiment, the mode change request may be a HARQ request, which requests the AP to switch from its current mode to a HARQ mode (e.g., an LRRE HARQ mode). In response, the response (described below) sent from the AP may be a HARQ response.

[0165] Next, the method 800 may proceed at 804. At 804, the method 800 may include receiving a response from the AP regarding the mode change request. In response, the receiver may receive a response from the AP regarding the mode change request.

[0166] Specifically, after receiving the mode change request, the AP may acknowledge the mode change request by transmitting a response (e.g., a mode change response or a HARQ request response) to the WTRU. The response may be a response frame (e.g., a HARQ request response frame). In an embodiment, the response frame may be a separate frame transmitted separately from the AP. In another embodiment, the response frame may be part of another frame transmitted by the AP (e.g., a trigger frame, a DL data frame, etc.). Although several examples of response frames are given above, it will be appreciated that they are not intended to be exclusive or limiting to the present application. The response frame may be implemented by any other available frame as long as those other available frames can help realize the principles of the present application. It will also be appreciated that the response frame may be transmitted by the WTRU to the AP if the AP is the sender of the mode change request described above. The following description further describes various scenarios for transmitting and receiving mode change requests.

[0167] The mode change request may be sent by a station (either the WTRU or the AP) initiating a mode change. For example, if the WTRU determines that the first condition above is met (e.g., the current distance between the WTRU and the AP is greater than a first value), the WTRU may send a mode change request to the AP to initiate a mode change. In that case, the AP receives the mode change request and then sends the response described above to the WTRU. If the AP determines that the first condition above is met (e.g., the distance between the AP and the WTRU is greater than a first value), the AP may send a mode change request to the WTRU to initiate a mode change. In that case, the WTRU receives the mode change request and then sends the response described above to the AP. Various scenarios for sending a mode change request and receiving a response regarding the mode change request are further illustrated with reference to additional embodiments below.

[0168] More specifically, to switch to LRRE HARQ operation, the WTRU / AP may request LRRE HARQ operation. If the AP / WTRU responds with a HARQ response and / or an operating mode change response, the AP and WTRU may begin LRRE HARQ operation. In one example, the mode change request / response (or HARQ request / HARQ response) process may be performed using an LRRE HARQ PPDU.

[0169] Additionally, the WTRU may request that the AP transmit an LRRE HARQ beacon to support the LRRE HARQ process. Such a request may be implied as part of the HARQ request or mode change request. The AP may then start transmitting the LRRE HARQ beacon, which is carried within the LRRE HARQ PPDU.

[0170] Method 800 may then proceed to process at 805. At 805, method 800 may include communicating with an AP via at least one physical layer convergence procedure (PLCP) protocol data unit (PPDU) using a PPDU structure, the PPDU structure comprising: (1) at least one field that enables transmission from the WTRU to the AP under a first condition; and / or (2) a field that includes an LRRE HARQ mode indication. In response, the WTRU may communicate with the AP via at least one physical layer convergence procedure (PLCP) protocol data unit (PPDU) using a PPDU structure, the PPDU structure comprising: (1) at least one field that enables transmission from the WTRU to the AP under a first condition; and / or (2) a field that includes an LRRE HARQ mode indication.

[0171] Specifically, after the above-described processes in 803 and 804, the WTRU has changed its operation mode to the LRRE HARQ mode, and the WTRU and the AP can communicate with each other in this mode. The term "communicate" means that the WTRU can transmit PPDUs to the AP, and the AP can also transmit PPDUs to the WTRU. The PPDU transmitted between the WTRU and the AP may be an LRRE HARQ PPDU having a PPDU structure specifically designed for transmission in the LRRE HARQ mode. Before describing the PPDU structure in detail, the following description first illustrates additional embodiments of the method according to the present application.

[0172] A second embodiment according to the present application will be described with reference to Figure 8B. Figure 8B shows an example flowchart of a method 800 according to the second embodiment of the present application. It should be noted that the method 800 shown in Figure 8B may be used by a WTRU according to the present application. It should be noted that in the second embodiment, unless otherwise indicated, the terms (e.g., first condition, mode change request, response, etc.) are the same as or similar to those in the first embodiment above.

[0173] As shown in FIG. 8B, the method 800 includes receiving LRRE information from an AP at 811; determining whether a first condition is met by the WTRU at 812; receiving a mode change request from the AP to change the operation mode to the LRRE HARQ mode at 813 on condition that the first condition is met; sending a response regarding the mode change request to the AP at 814; and communicating with the AP via a PPDU using a PPDU structure at 815, the PPDU structure comprising: (1) at least one field that enables transmission between the WTRU and the AP under the first condition; and (2) an LRRE HARQ mode indication.

[0174] A third embodiment according to the present application will be described with reference to FIG. 8C. FIG. 8C shows an exemplary flowchart of a method 800 according to the third embodiment of the present application. It should be noted that the method 800 shown in FIG. 8C may be used by an AP according to the present application. It should be noted that in the third embodiment, unless otherwise indicated, the terms (e.g., first condition, mode change request, response, etc.) are the same as or similar to those in the first embodiment above.

[0175] As shown in FIG. 8C, the method 800 includes receiving LRRE information from a WTRU at 821, determining whether a first condition is met at 822, sending a mode change request to the WTRU to change the operation mode to the LRRE HARQ mode on condition that the first condition is met at 823, receiving a response regarding the mode change request from the WTRU at 824, and communicating with the WTRU via a PPDU using a PPDU structure at 825, the PPDU structure comprising: (1) at least one field that enables transmission between the WTRU and the AP under the first condition; and (2) an LRRE HARQ mode indication.

[0176] A fourth embodiment according to the present application will be described with reference to Fig. 8D. Fig. 8D shows an exemplary flowchart of a method 800 according to the fourth embodiment of the present application. It should be noted that the method 800 shown in Fig. 8D may be used by an AP according to the present application. It should be noted that in the fourth embodiment, unless otherwise indicated, the terms (e.g., first condition, mode change request, response, etc.) are the same as or similar to those in the first embodiment above.

[0177] As shown in FIG. 8D , method 800 includes receiving LRRE information from a WTRU at 831; determining whether a first condition is met at 832; receiving a mode change request from the WTRU to change the operation mode to the LRRE HARQ mode on condition that the first condition is met at 833; sending a response regarding the mode change request to the WTRU at 834; and communicating with the WTRU via a PPDU using a PPDU structure at 835, the PPDU structure comprising: (1) at least one field that enables transmission between the WTRU and the AP under the first condition; and (2) an LRRE HARQ mode indication.

[0178] The following description describes the PPDU structure used by the LRRE PPDU according to the present application. For clarity, the LRRE PPDU may also be referred to as a PPDU. The newly designed PPDU according to the present application may be required for 6 GHz HE or EHT devices.

[0179] As mentioned above, the PPDU structure may comprise at least one field that enables transmission between the WTRU and the AP under a first condition. Preferably, the at least one field may include multiple fields that enable transmission within the 6 GHz band.

[0180] In an embodiment, the multiple fields enabling transmission within the 6 GHz band may include at least one high-efficiency 6 GHz short training field (HE-6GHz-STF), at least one HE 6 GHz long training field (HE-6GHz-LTF), and at least one HE 6 GHz signal field (HE-6GHz-SIG). Figure 9 shows an HE 6 GHz PPDU structure as an example of a PLCP preamble for an HE or EHT device for the 6 GHz band.

[0181] 9, the HE6GHz PPDU may include multiple HE6GHz compatibility portions (e.g., fields) when transmitted within the 6GHz band. As shown in FIG. 9, the HE6GHz PPDU may include at least one HE-6GHz-STF (e.g., HE-6GHz-STF 901), at least one HE-6GHz-LTF (e.g., HE-6GHz-LTF 902, 904, and 905), at least one HE-6GHz-SIG (e.g., HE-6GHz-SIG 903), and a data field 906.

[0182] In an embodiment, the HE-6GHz-STF and HE-6GHz-LTF shown in Figure 9 may follow the designs of those commonly known in the art as HE STF and HE LTF. In another embodiment, the HE-6GHz-STF and / or HE-6GHz-LTF may be designed differently to transmit in LRRE HARQ mode, i.e., to help provide range extension according to the present application.

[0183] For example, the HE-6GHz-STF and / or HE-6GHz-LTF shown in FIG. 9 may have more bits than their counterparts commonly known in the art, which may result in increased received power at a station (e.g., a WTRU or AP) or increased transmit power at the station. That is, the HE-6GHz-STF and / or HE-6GHz-LTF may be extended in length. Preferably, the HE-6GHz-STF and / or HE-6GHz-LTF may have twice as many bits as their counterparts commonly known in the art. That is, the HE-6GHz-STF and / or HE-6GHz-LTF may be twice as long as the commonly known HE STF and HE LTF, which may result in increased received power at a station (e.g., a WTRU or AP) (e.g., the received power at the station may increase by 3 dB) or increased transmit power at the station. It will be appreciated that the received power at a station may vary based on different designs of the HE-6GHz-STF and / or HE-6GHz-LTF, and therefore the 3dB example is not intended to be exclusive or limiting to this application.

[0184] In an embodiment, the number of these HE-6GHz fields may also be increased to increase the transmit power or received power at the station. For example, the number of HE-6GHz-STFs and / or HE-6GHz-LTFs may be doubled compared to those HE-STFs and HE-LTFs in a conventionally known PPDU. Preferably, there may be two HE-6GHz-STFs and four HE-6GHz-LTFs. These HE-6GHz-STFs and / or HE-6GHz-LTFs may carry phase rotation or different modulation or other indication that they are part of an LRRE HARQ PPDU, which may be a PPDU transmitted using the LRRE HARQ scheme.

[0185] The PPDU structure may also comprise an LRRE HARQ mode indication that indicates whether the LRRE HARQ PPDU is transmitting in LRRE HARQ mode or that the PPDU is an LRRE HARQ PPDU. The LRRE HARQ mode indication may be any one or combination of the generation, type, TXOP, and HARQ parameters described below.

[0186] In an embodiment, at least one field in the PPDU structure may comprise a first subfield indicating a generation of the PPDU, i.e., a generation subfield, and the at least one field comprising the first subfield may be any one of HE-6GHz-STF, HE-6GHz-LTF, and HE-6GHz-SIG.

[0187] For example, as shown in Figure 9, the HE-6GHz-SIG field comprises a Generation subfield 907. The Generation subfield may contain an indication of the generation of the PPDU that follows the HE-6GHz-SIG. Possible values ​​may include 11ax, EHT, or a future generation of the PPDU. The format of the rest of the PPDU may depend on the generation indication provided in this subfield.

[0188] In an embodiment, at least one field in the PPDU structure may comprise a second subfield, i.e., a type subfield, indicating the type of PPDU following the HE-6GHz-SIG. The at least one field comprising the second subfield may be any one of HE-6GHz-STF, HE-6GHz-LTF, and HE-6GHz-SIG.

[0189] For example, as shown in Figure 9, the HE-6GHz-SIG field comprises a Type subfield 908. Possible values ​​of Type may include SU, MU, trigger-based PPDU, MU-MIMO PPDU, SU-MIMO PPDU, HARQ PPDU, OFDMA PPDU, multi-AP joint transmission, and multi-AP HARQ. The Type of the PPDU may indicate the format of the remaining PPDU. For example, if the Type of the PPDU indicates that it is an LRRE HARQ PPDU or an extended range PPDU, the PPDU may carry additional HARQ parameters.

[0190] In an embodiment, at least one field in the PPDU structure may comprise a third subfield containing transmission opportunity (TXOP) information, i.e., a TXOP subfield. The at least one field comprising the third subfield may be any one of HE-6GHz-STF, HE-6GHz-LTF, and HE-6GHz-SIG.

[0191] 9, the HE-6GHz-SIG field comprises a TXOP subfield 909. The TXOP subfield may carry TXOP-related information. For example, the TXOP may be a request for an uplink TXOP if carried in a PPDU from the WTRU to the AP, which may be indicated by the UPLINK flag being set to 1 in the PLCP preamble.

[0192] In an embodiment, at least one field in the PPDU structure may comprise a fourth subfield, i.e., a HARQ parameter subfield, that includes at least one HARQ parameter. The at least one field comprising the fourth subfield may be any one of HE-6GHz-STF, HE-6GHz-LTF, and HE-6GHz-SIG.

[0193] For example, as shown in Figure 9, the HE-6GHz-SIG field comprises a HARQ parameters subfield 910. The HARQ parameters subfield may include HARQ-related parameters such as a HARQ process ID, an RV, an indication of initial transmission or retransmission, etc. In an embodiment, the first part of the HE 6GHz preamble (e.g., the HE-6GHz-SIG) may indicate that the HE PPDU may be an LRRE HARQ PPDU or an extended range HARQ PPDU (i.e., the first part of the HE 6GHz preamble may include an LRRE HARQ mode indication), and a later part of the HE 6GHz preamble (e.g., HE-6GHz-SIG2 not shown in Figure 9) may include the HARQ parameters.

[0194] FIG. 9 illustrates that the HE-6GHz-SIG field may include one or more subfields or parameters. Note that the one or more fields may include, but are not limited to, the above-described subfields of Generation, Type, TXOP, and HARQ parameters. The example illustrated in FIG. 9 is not intended to be exclusive or limiting to the present application. In an embodiment, the above-described subfields may be included in one of other fields, such as HE-6GHz-STF and HE-6GHz-LTF. In another embodiment, the above-described subfields may be included in multiple fields illustrated in FIG. 9 simultaneously.

[0195] In an embodiment, the multiple fields enabling transmission within the 6 GHz band may include at least one very high throughput 6 GHz short training field (EHT-6GHz-STF), at least one EHT 6 GHz long training field (EHT-6GHz-LTF), and at least one EHT 6 GHz signal field (EHT-6GHz-SIG). Figure 10 shows the EHT 6 GHz PPDU structure.

[0196] As shown in Figure 10, an EHT 6GHz PPDU may comprise multiple EHT 6GHz compatibility portions (e.g., fields) when being transmitted within the 6GHz band. As shown in Figure 10, an EHT 6GHz PPDU may include at least one EHT-6GHz-STF (e.g., EHT-6GHz-STF 1001), at least one EHT 6GHz LTF (e.g., EHT-6GHz-LTF 1002), at least one EHT-6GHz-SIG (e.g., EHT-6GHz-SIG 1003), and data 1006.

[0197] In an embodiment, the EHT-6GHz-STF and EHT-6GHz-LTF shown in Figure 10 may follow the design of the EHT STF field and EHT LTF field commonly known in the art. In another embodiment, the EHT-6GHz-STF and EHT-6GHz-LTF may be designed differently to transmit in LRRE HARQ mode, i.e., to help provide range extension according to the present application.

[0198] For example, the EHT-6GHz-STF and / or EHT-6GHz-LTF shown in FIG. 10 may have more bits than their counterparts commonly known in the art, which may result in increased received power at a station (e.g., a WTRU or AP) or increased transmitting power at the station. That is, the EHT-6GHz-STF and / or EHT-6GHz-LTF may be extended in length. Preferably, the EHT-6GHz-STF and / or EHT-6GHz-LTF may have twice as many bits as their counterparts commonly known in the art. That is, the EHT-6GHz-STF and / or EHT-6GHz-LTF may be twice as long as their commonly known EHT STF and / or EHT LTF, which may result in increased received power at a station (e.g., a WTRU or AP) or increased transmitting power at the station. Preferably, the received power at a station receiving the PPDU may increase by 3 dB. It will be appreciated that the received power at a station may vary based on different designs of the EHT-6GHz-STF and / or EHT-6GHz-LTF, and therefore the 3dB example is not intended to be exclusive or limiting to this application.

[0199] In an embodiment, the number of these EHT 6GHz fields may also be increased to increase the transmit power or received power at the station. For example, the number of EHT-6GHz-STFs and / or EHT-6GHz-LTFs may be doubled compared to the EHT-STFs and EHT-LTFs in a conventionally known PPDU. Preferably, there may be two EHT-6GHz-STFs and four EHT-6GHz-LTFs. These EHT-6GHz-STFs and / or EHT-6GHz-LTFs may carry phase rotation or different modulation or other indication that they are part of an LRRE HARQ PPDU, which may be a PPDU transmitted using the LRRE HARQ scheme.

[0200] The PPDU structure may also comprise an LRRE HARQ mode indication that indicates that the LRRE HARQ PPDU is transmitting in LRRE HARQ mode or that the PPDU is an LRRE HARQ PPDU. For example, LRRE HARQ PPDUs may include an indication in their PLCP preamble that they are LRRE HARQ PPDUs, which may indicate an additional number of STF and LTF fields or an additional power boost for the SIG field in the PLCP preamble. In another example, additional fields, such as additional STF, LTF, and / or SIG fields, and / or HARQ parameter fields, may be added to the PLCP preamble to ensure that the HARQ information can be correctly decoded at the receiving station (e.g., WTRU).

[0201] This LRRE HARQ mode indication may be any one or combination of the generation, type, TXOP, and HARQ parameters described below.

[0202] In an embodiment, at least one field in the PPDU structure may comprise a first subfield indicating a generation of the PPDU, i.e., a generation subfield, and the at least one field comprising the first subfield may be any one of EHT-6GHz-STF, EHT-6GHz-LTF, and EHT-6GHz-SIG.

[0203] For example, as shown in FIG. 10, the EHT-6GHz-SIG field comprises a generation subfield 1007. The generation subfield may include an indication of the generation of the PPDU that follows the EHT-6GHz-SIG. Possible values ​​may include 11ax, EHT, or a future generation of the PPDU. The format of the remainder of the PPDU may depend on the generation indication provided in this subfield. Other types of generation indications may indicate that a wider or narrower band transmission follows the PLCP preamble.

[0204] In an embodiment, at least one field in the PPDU structure may comprise a second subfield, i.e., a type subfield, indicating the type of PPDU following the EHT-6GHz-SIG. The at least one field including the second subfield may be any one of EHT-6GHz-STF, EHT-6GHz-LTF, and EHT-6GHz-SIG.

[0205] For example, as shown in Figure 10, the EHT-6GHz-SIG field comprises a type subfield 1008. Example possible values ​​may include, but are not limited to, SU, MU, trigger-based PPDU, MU-MIMO PPDU, SU-MIMO PPDU, HARQ PPDU, OFDMA PPDU, multi-AP joint transmission, and multi-AP HARQ. The type of the PPDU may indicate the format of the remaining PPDU. For example, if the type of the PPDU indicates that it is an LRRE HARQ PPDU or an extended range PPDU, the PPDU may carry additional HARQ parameters.

[0206] In an embodiment, at least one field in the PPDU structure may comprise a third subfield, i.e., a TXOP subfield, that contains transmission opportunity (TXOP) information. The at least one field comprising the third subfield may be any one of EHT-6GHz-STF, EHT-6GHz-LTF, and EHT-6GHz-SIG. For example, as shown in Figure 10, the EHT-6GHz-SIG field comprises a TXOP subfield 1009. The contents of the TXOP subfield may be defined similarly to the subfields defined above with reference to Figure 9.

[0207] In an embodiment, at least one field in the PPDU structure may comprise a fourth subfield, i.e., a HARQ parameter subfield, that includes at least one HARQ parameter. The at least one field comprising the fourth subfield may be any one of EHT-6GHz-STF, EHT-6GHz-LTF, and EHT-6GHz-SIG. For example, as shown in Figure 10, the EHT-6GHz-SIG field comprises a HARQ parameter subfield 1010. The HARQ parameters may be defined similarly to the HARQ parameters defined above with reference to Figure 9.

[0208] Without loss of generality, the design of the LRRE HARQ PPDU on other bands can follow a similar design pattern, for example, the design of the LRRE HARQ PPDU on the 5 GHz band may have a similar design to that shown in Figures 9-10.

[0209] FIG. 10 shows that the EHT-6GHz-SIG field may include one or more subfields or parameters. Note that the one or more fields may include, but are not limited to, the above-described subfields of Generation, Type, TXOP, and HARQ parameters. The example shown in FIG. 10 is not intended to be exclusive or limiting to the present application. In an embodiment, the above-described subfields may be included in one of the other fields, such as EHT-6GHz-STF and EHT-6GHz-LTF. In another embodiment, the above-described subfields may be included in multiple fields shown in FIG. 10 simultaneously.

[0210] Preferably, the at least one field includes at least one extremely high throughput short training field (EHT STF), at least one EHT long training field (EHT LTF), at least one EHT signal field (EHT SIG), and at least one EHT mark field (EHT Mark).

[0211] Figure 11 shows an example of an EHT PPDU structure for multiple frequency bands. In one example, for the 2.4, 5 GHz band, or other band, the LRRE HARQ PPDU may include an additional indication that the PPDU is a HARQ PPDU. An exemplary design of an EHT PPDU structure according to the present application is shown in Figure 11. The EHT PPDU may be transmitted on frequency bands that may have older generation WLAN devices operating in sub-1 GHz, 2.4 GHz, 5 GHz bands, etc.

[0212] As shown in FIG. 11, an exemplary design of an EHT PPDU may have one or more of fields such as EHT MARK 1104, EHT STF 1105, EHT LTF 1106 and 1108, EHT SIG A 1107, and EHT SIG B 1109 after the conventional portion (e.g., L-STF, L-LTF, and L-SIG).

[0213] The EHT MARK field may contain an indication that the PPDU is an EHT PPDU. In addition, there may be an additional indication that the current PPDU is an LRRE HARQ PPDU. Thus, the EHT MARK may be considered as the LRRE HARQ mode indication described above.

[0214] The EHT STF field may provide an STF for EHT devices. The number of EHT STF fields may depend on whether there is an indication that the current PPDU is an LRRE HARQ PPDU in the EHT MARK 1104. The EHT STF may have the same or similar functionality as that shown in FIG. 9 to increase the transmit power at a station (e.g., a WTRU) or increase the receive power at a station (e.g., an AP).

[0215] The EHT LTF field may provide the LTF for the EHT device. The number of EHT LTF fields may depend on whether there is an indication that the current PPDU is an LRRE HARQ PPDU in the EHT MARK 1104. The EHT LTF may have the same or similar function as that shown in FIG. 9 to increase the transmit power at a station (e.g., a WTRU) or increase the receive power at a station (e.g., an AP).

[0216] The EHT SIG A subfield may partially provide the SIG indication for the remainder of the PPDU. The EHT SIG B subfield may partially provide the SIG indication for the remainder of the PPDU.

[0217] The PPDU structure may also include an LRRE HARQ mode indication indicating that the LRRE HARQ PPDU is transmitting in LRRE HARQ mode or that the PPDU is an LRRE HARQ PPDU. This LRRE HARQ mode indication may be any one or combination of the Generation, Type, TXOP, and HARQ Parameters subfields described below. In one example, one or more of the EHT Mark, EHT STF, EHT LTF, EHT SIG A, and EHG SIG B fields in the EHT PLCP preamble may include one or more of the Generation, Type, TXOP, and HARQ Parameters subfields. The Generation, Type, TXOP, and HARQ Parameters subfields may be defined similarly to the subfields defined above with reference to FIG. 9.

[0218] For example, as shown in FIG. 11, one or more of the above fields may comprise a generation subfield 1111. The generation subfield may include an indication of the generation of the PPDU. Possible values ​​may include 11ax, EHT, or a future generation of the PPDU, 11ba+. The format of the rest of the PPDU may depend on the generation indication provided in this subfield. Other types of generation indications may indicate that a wider or narrower band transmission follows the PLCP preamble.

[0219] As shown in FIG. 11 , one or more of the above fields may comprise a type subfield 1112 indicating the type of the PPDU and may follow a SIG (e.g., L-SIG and EHT SIG A). Example possible values ​​may include, but are not limited to, SU, MU, trigger-based PPDU, MU-MIMO PPDU, SU-MIMO PPDU, HARQ PPDU, OFDMA PPDU, multi-AP transmission, multi-AP joint transmission, and multi-AP HARQ. The PPDU type indication may define the format of the remaining PPDU. For example, if the PPDU type indicates that it is a HARQ PPDU or an extended range PPDU, the PPDU may carry additional HARQ parameters.

[0220] 11, the one or more fields may comprise a TXOP subfield 1113, and the one or more fields may comprise a HARQ parameters subfield 1114. The TXOP subfield and the HARQ parameters subfield may be defined similarly to the subfields defined above with reference to FIG.

[0221] Alternatively or additionally, the AP may request an operating mode change by sending a mode change request or HARQ request, which may include a HARQ mode, HARQ type, or parameters similar to those described above. The WTRU may respond with a response or HARQ response.

[0222] Once the response / HARQ response is successfully received, the WTRU and AP may communicate with each other using HARQ operations (eg, using their LRRE HARQ PPDUs, as described above).

[0223] During communication between the WTRU and the AP, either of them may send a disassociation request carried within an LRRE HARQ PPDU to perform disassociation.

[0224] An embodiment for LRRE HARQ association support is described as follows: The WTRU may utilize LRRE HARQ operation to associate with an AP that supports the operation. The LRRE HARQ association procedure may be as follows:

[0225] An AP can transmit an LRRE HARQ beacon carried within an LRRE PPDU to support the LRRE HARQ association process. LRRE HARQ PPDUs may include an indication in their PLCP preamble that they are LRRE HARQ PPDUs, which may indicate an additional number of STFs and LTFs or an additional power boost for the SIG field in the PLCP preamble. In one example, additional fields, such as additional STFs, LTFs, and / or SIG fields, and / or HARQ parameter fields, may be added to the PLCP preamble to ensure that the HARQ information can be correctly decoded at the receiving STA.

[0226] In another example, the number of LRRE HARQ beacons may be transmitted consecutively or at fixed intervals so that the beacons can be combined at the receiving STAs, and the TSF timer may be the same across the number of LRRE HARQ beacons to ensure combination.

[0227] The WTRU may receive the LRRE HARQ beacon, or it may be aware of the presence of the AP from prior knowledge or from ESS information. The WTRU may transmit several probe request, authentication request, and / or (re)association request frames carried in the LRRE PPDU consecutively or at fixed intervals so that the packets can be correctly combined at the receiving AP. The probe request / response, authentication request / response, and (re)association request / response may include a HARQ request element. The WTRU and the AP may then exchange packets carried in the LRRE PPDU to communicate over an extended range.

[0228] As channel conditions improve, the WTRU or AP may decide to change the operating mode to use standard PPDU or other HARQ operation, i.e., to stop using the LRRE HARQ mode and swift to another operating mode (e.g., the default mode).

[0229] An embodiment for HARQ resource allocation via 2.4 GHz assistance is described as follows: If the AP generally has 5 dB transmit power or more (i.e., power greater than that of the WTRU), then the WTRU at the cell edge may be able to receive beacons and broadcast control frames in the DL, but the WTRU may not be able to reach the AP in the UL direction.

[0230] In broadcast-triggered TWT, the dedicated / random access RU size / location / target UL RSSI / MSC assigned by the AP in the trigger frame (TF) within the TWT service period may not be feasible by the WTRU moving to the cell edge by the time of its last radio contact with the AP.

[0231] FIG. 12 shows an example of a frequency selective channel. As shown in FIG. 12, based on the estimated channel of a recently received DL broadcast (beacon) frame, a WTRU may be able to reach the AP if a "good resource unit (good RU)" is assigned to the WTRU. If the assigned RU (or the RU derived from the random access procedure) happens to be a "bad RU," the WTRU may not be able to reach the AP. When a STA receives a beacon frame allocating a broadcast TWT service period, the STA has no idea which scenario will occur when the TWT service period begins.

[0232] In one embodiment, the MCS selection may be decided by the WTRU instead of being signaled in the TF. The "minimum target UL RSSI" (or possibly "minimum RU size" / "minimum UL duration") may be indicated by the AP in a beacon frame, and the WTRU may rely on this information and its power headroom derived from the path loss (possibly based on the beacon frame) to select an MCS. The WTRU may select its MCS after receiving the TF, which indicates the size / location of the RU.

[0233] In another embodiment, random access RUs may not be contiguous and may be interlaced with dedicated / non-allocated RUs. STAs with DL RSSI below a certain threshold may not follow the random RU index selection procedure currently defined in 11ax, and instead select a feasible random access RU that meets the power headroom constraint.

[0234] In another embodiment, an AP can use its 5 / 6 GHz beacon frame to allocate not only broadcast TWT service periods in the 5 / 6 GHz primary channel, but also TWT service periods in 2.4 GHz channels operated by the same / co-located APs. Considering congestion in the 2.4 GHz band, such service periods may be short and are expected not to occupy too much channel time.

[0235] In this embodiment, a triggered TWT in the 2.4 GHz band can precede a triggered TWT in the 5 / 6 GHz band. Based on its observation of beacon frames in the 5 / 6 GHz primary channel and the above-specified information contained in the beacon frames, the WTRU can determine that some RU allocations will not be able to reach the AP. Such a WTRU can perform random access within the 2.4 GHz triggered TWT. For this UL transmission, which generally reaches a longer distance than within the 5 / 6 GHz channel, the WTRU can indicate its preferred 5 / 6 GHz UL RU index and MCS to bootstrap a scheduled UL transmission within the 5 / 6 GHz band.

[0236] If the UL payload is short, the WTRU can terminate the payload transmission in the 2.4 GHz PPDU and indicate that UL resources are not required. If the UL payload is not completely transmitted within the duration of the 2.4 GHz trigger-based (TB) PPDU, the AP can use the indicated information to schedule UL transmission in the 5 / 6 GHz triggered TWT with a feasible RU index and power control setting for the STA.

[0237] 13 illustrates an exemplary cell edge station (i.e., WTRU) bootstrapping 5 / 6 GHz uplink (UL) resource unit (RU) allocation using a 2.4 GHz target wake time (TWT) service period (SP). As shown in FIG. 13, after receiving a beacon frame (i.e., beacon 1301) in 5 / 6 GHz, four WTRUs (i.e., STA1, STA2, STA3, and STA4) determine that they cannot reach the AP based on the "minimum target UL RSSI" and minimum MCS provided on several RU indices. They perform random access in 2.4 GHz within the triggered TWT, which was signaled in the beacon frame.

[0238] If the path loss in the 2.4 GHz band is low, the transmission between the WTRU and the AP may be successful. The AP may receive their preferred UL RU index / MCS and achievable target RSSI. STA2 may have a short payload so that it indicates that no more UL resources are needed for UL transmission. STAs 1, 3, and 4 may tune to the 5 / 6 GHz channel for the scheduled 5 / 6 GHz TWT. Within the TFs (e.g., TFs 1302, 1304, and 1306) that initiate the TWT, STAs 1, 3, and 4 may be scheduled using their indicated RU / MCS. TB-PPDU reception may be successful for STA 4 but not for STAs 1 and 3. The AP may schedule HARQ retransmissions for STAs 1 and 3 in the next TB-PPDU within the same TWT service period using their preferred settings.

[0239] In this embodiment, the UL transmission at 2.4 GHz may be similar to the "preamble" for the next 5 / 6 GHz UL transmission, assuming the likelihood of decoding the preamble increases with improved path loss.

[0240] An embodiment for a collision-aware HARQ transmission procedure is described as follows.

[0241] In general, blank periods or resources during which the transmitter does not transmit any power may be configured within a transmitted packet to allow the receiver to continuously estimate the SINR of the packet and identify the occurrence of a collision based on this estimate. The following sections detail various examples whereby this may be implemented in an EHT.

[0242] First, an embodiment for a no-power midamble for collision estimation is described herein.

[0243] In one embodiment, a dedicated midamble with no power transmitted from the transmitter may be used. The receiving STA can estimate the interference power from these resources and use this to estimate the presence or absence of a collision. The midambles may be configured to occur at specified intervals in a manner that is STA-specific or BS-specific. The STA-specific midamble has a midamble pattern that is specific to each STA (or group of STAs) in a BSS. This assumes that collisions may occur from STAs in the same BSS. Signaling about the location of the collision estimation midamble may be placed in the EHT preamble. The BSS-specific midamble occurs so that all STAs in a BSS may have the same midamble structure. This assumes that collisions are from OBSS STAs. The signaling about the location of the collision estimation midamble may be placed in the EHT preamble, sent by a dedicated collision estimation midamble configuration packet, configured in a beacon, or set up during STA association.

[0244] 13 shows an exemplary no-power collision estimation midamble. The location of the midamble may be static (i.e., fixed for the duration of the packet) or dynamic (i.e., changing over the duration of the packet).

[0245] The AP and STA may include a capability bit indicating support for collision estimation midambles.

[0246] The CE midamble signaling, eg, the EHT preamble, may include a bit that indicates the presence of a collision estimation midamble in the packet.

[0247] The CE midamble signaling, for example the EHT preamble, may include a field that indicates the location of the first collision estimation midamble.

[0248] The CE midamble signaling, for example the EHT preamble, may include a field indicating the collision estimation midamble update interval.

[0249] The CE midamble signaling, eg, the EHT preamble, may include a field indicating the number of OFDM symbols used for the collision estimation midamble.

[0250] An embodiment of partial power midambles for collision estimation will be described with reference to Figure 14. As shown in Figure 14, each of the stations (i.e., STA1 and STA2) comprises a PPDU comprising fields of a preamble, data, and a CE midamble. For example, a first PPDU may comprise preamble 1401, data 1402, 1404, and 1406, and CE midambles 1403 and 1405. A second PPDU may comprise preamble 1411, data 1412, 1414, and 1416, and CE midambles 1413 and 1415.

[0251] In one embodiment, a dedicated midamble may be used with power transmitted on some OFDM tones and no power transmitted on others. The midamble configuration may be configured similarly to the no-power midamble described above. The receiving STA estimates the SINR from these resources and uses this to estimate the presence or absence of collisions.

[0252] The AP and STA may include a capability bit indicating support for collision estimation midambles.

[0253] The CE midamble signaling, eg, the EHT preamble, may include a bit that indicates the presence of a collision estimation midamble in the packet.

[0254] The CE midamble signaling, for example the EHT preamble, may include a field that indicates the location of the first collision estimation midamble.

[0255] The CE midamble signaling, for example the EHT preamble, may include a field indicating the collision estimation midamble update interval.

[0256] The CE midamble signaling, eg, the EHT preamble, may include a field indicating the number of OFDM symbols used for the collision estimation midamble.

[0257] The CE midamble signaling, eg, the EHT preamble, may include a field indicating which OFDM subcarriers are at zero power.

[0258] In one example, the CE midamble may consist of an LTF signal, eg, EHT-LTF, with a predetermined set of punctured subcarriers on which no power is transmitted.

[0259] In one example, the CE midamble may be comprised of an LTF signal, e.g., EHT-LTF or HE-LTF, having an indicated set of punctured subcarriers on which no power is transmitted. For example, the starting subcarriers and subcarrier spacing may be indicated by CE midamble signaling, e.g., an EHT preamble. As shown in FIG. 15, a first PPDU may comprise preamble 1501, data 1502, 1504, and 1506, and CE midambles 1503 and 1505. A second PPDU may comprise preamble 1511, data 1512, 1514, and 1516, and CE midambles 1513 and 1515.

[0260] An embodiment of a partial power midamble and Doppler for collision estimation will be described with reference to Figure 16. Figure 16 shows an exemplary combined Doppler and collision estimation midamble. As shown in Figure 16, Doppler midambles 1603 and 1606 defined in 802.11ax may be combined with the CE estimation midamble. In this case, additional OFDM symbols may be added to the Doppler estimation midamble for SINR estimation as shown in Figure 16. As shown in Figure 16, a PPDU may comprise preamble 1601, data 1602, 1605, and 1608, and CE midambles 1604 and 1607.

[0261] Alternatively or additionally, the Doppler midamble may be punctured with zeros to allow for SINR and collisions, as shown in Figure 17. As shown in Figure 17, a PPDU may comprise a preamble 1701, data 1702, 1704, and 1706, and CE / Doppler midambles 1703 and 1705.

[0262] An embodiment for a no-power pilot for collision estimation is described below.

[0263] In one embodiment, each OFDM symbol may have a zero-power pilot at a unique location within the packet. Current 802.11ax packets use the following numerology: Pilot subcarriers: 26 tones with 2 pilots, 52 tones with 4 pilots, 106 tones with 4 pilots, 242 tones with 8 pilots, 484 tones with 16 pilots, and 996 tones with 16 pilots.

[0264] In one embodiment, an equal number of no-power pilots may be deployed in each RU. Alternatively or additionally, a reduced number of no-power pilots may be deployed in each RU, such as no-power pilot subcarriers: 26 tones with 1 pilot, 52 tones with 2 pilots, 106 tones with 2 pilots, 242 tones with 4 pilots, 484 tones with 8 pilots, and 996 tones with 8 pilots.

[0265] The pilot locations may be STA-specific or BSS-specific, or the pattern may be static or dynamic.

[0266] SUMMARY Embodiments for a power-free resource unit for collision estimation are described herein.

[0267] FIG. 18 shows an example no-power resource unit for collision estimation. RUs or partial RUs may be set to no-power transmission to enable collision estimation. As RUs extend the duration of a packet, the index of the OFDM symbol within the RU can be set to no-power to reduce overhead. Note that based on the collision behavior of scheduled STAs, different RUs may have different frequencies / distributions of no-power RU symbols. As shown in FIG. 18, no-power RU 1801 may comprise RU1, symbol 2; RU3, symbol 3; and RU2, symbol 4. Data RU 1802 may comprise the other elements shown in FIG. 18.

[0268] Embodiments for collision estimation and collision-aware HARQ procedures are described herein.

[0269] 19 shows an example procedure for collision estimation in collision-aware HARQ, in which STA-specific collision estimation may be assumed.

[0270] At 1901, the STA can receive the EHT preamble.

[0271] At 1902, a STA can identify the location of STA-specific collision estimation resources, which may include both unpowered and powered resources.

[0272] At 1903, the STA may estimate the presence of a collision, which may be based on interference metrics, such as SINR variation, interference power variation, packet duration over, etc.

[0273] At 1904, the STA may decode the packet based on the collision estimation. In one example, the STA may implement a HARQ-aware decoder at 1905 and combine packets if there are no collisions. The transmitter then transmits feedback at 1906. In another example, the STA may estimate that it is operating in the non-HARQ range (i.e., ARQ is better than HARQ) and send a request to the AP to turn off HARQ transmissions. Note that in CC HARQ, the transmissions may be the same. However, in IR-HARQ, the transmissions may be different, and if ARQ was used, the best RV may always be transmitted.

[0274] A STA / AP can request that the AP / STA change its collision estimation resource to allow for better estimation of interference from other colliding STAs. Figure 20 shows an example of the collision estimation resource change process. As shown in Figure 20, there is a receiver 2005 and a transmitter 2006.

[0275] At 2001, a WTRU (e.g., receiver 2005) may receive CE resource signaling from an AP (e.g., transmitter 2006). At 2002, the WTRU may send a CE resource change request to the AP. At 2003, the AP may send a CE resource change response to the WTRU. At 2004, the AP may send new CE resource signaling to the WTRU. More specifically, in one embodiment, the STA / AP may suggest possible CE resources by reviving the LLR of a received packet and may be able to identify resources with an LLR close to zero (i.e., a probability of one or zero equally means that performance is uncertain). In one example, the STA / AP may send a CE resource request packet to a transmitter indicating the desired resources.

[0276] Although features and elements of the present invention have been described in preferred embodiments in specific combinations, each feature or element may be used alone without the other features and elements of the preferred embodiments, or in various combinations with or without other features and elements of the present invention.

[0277] Although the solutions described herein take into account 802.11 specific protocols, it is understood that the solutions described herein are not limited to this scenario and are applicable to other wireless systems as well.

[0278] Although SIFS was used in the design and procedure examples to indicate various interframe intervals, all other interframe intervals such as RIFS, AIFS, DIFS or other agreed time intervals may be applied in the same solution.

[0279] Although four RBs per triggered TXOP are shown as an example in some figures, the actual number of RBs / channels / bandwidth utilized may vary.

[0280] Although features and elements are described above in particular combinations, those skilled in the art will appreciate that each feature or element may be used alone or in any combination with the other features and elements. The methods described herein may be implemented in a computer program, software, or firmware embodied 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 connections) and computer-readable storage media. Examples of computer-readable storage media include, but are not limited to, ROM, RAM, registers, cache memory, semiconductor memory devices, magnetic media such as internal hard disks and removable disks, magneto-optical media, and optical media such as CD-ROM disks and digital versatile disks (DVDs). Software and an associated processor may be used to implement a radio frequency transceiver for use in a WTRU, UE, terminal, base station, RNC, or any host computer.

Claims

1. A method performed by a station (STA), comprising: receiving information from an access point (AP) indicating a target wake time (TWT) service period in a first frequency band and a TWT service period in a second frequency band; transmitting an uplink preference indication for the first frequency band during the TWT service period in the second frequency band; receiving from the AP an allocation of uplink resources in the first frequency band based on the transmitted uplink preference indication for the first frequency band; A method for providing the above.

2. The method of claim 1 , wherein the first frequency band is a 5 GHz band or a 6 GHz band.

3. The method of claim 1 , wherein the second frequency band is the 2.4 GHz band.

4. 2. The method of claim 1, wherein the uplink preference indication for the first frequency band includes at least one of: (i) a preferred resource unit (RU) index for the first frequency band; or (ii) a preferred modulation and coding scheme (MSC) for the first frequency band.

5. 2. The method of claim 1, wherein the uplink preference indication for the first frequency band includes at least one of: (i) an indication of an achievable target uplink received power; or (ii) a target uplink received signal strength indicator (RSSI) for the first frequency band.

6. 2. The method of claim 1, wherein the information indicating the TWT service period in the first frequency band and the TWT service period in the second frequency band is included in a beacon frame transmitted by the AP in the first frequency band.

7. 10. The method of claim 1, wherein if a payload length is less than a threshold, the STA completes transmission of the payload in a physical layer protocol data unit (PPDU) on the second frequency band.

8. 8. The method of claim 7, wherein the PPDU indicates that uplink resources in the first frequency band are not required.

9. determining a modulation and coding scheme (MCS) for the first frequency band based on a power headroom derived from a path loss estimated from a downlink broadcast frame received in the first frequency band; receiving a trigger frame indicating at least a size or a location of a resource unit; selecting the MCS based on the trigger frame; The method of claim 1 further comprising:

10. A transceiver; Processor and A station (STA) comprising: The transceiver and the processor receiving information from an access point (AP) indicating a target wake time (TWT) service period in a first frequency band and a TWT service period in a second frequency band; transmitting an uplink preference indication for the first frequency band during the TWT service period in the second frequency band; receiving from the AP an allocation of uplink resources in the first frequency band based on the transmitted uplink preference indication for the first frequency band; STA configured as follows.

11. The STA of claim 10 , wherein the first frequency band is a 5 GHz band or a 6 GHz band.

12. The STA of claim 10 , wherein the second frequency band is the 2.4 GHz band.

13. 11. The STA of claim 10, wherein the uplink preference indication for the first frequency band includes at least one of: (i) a preferred resource unit (RU) index for the first frequency band; or (ii) a preferred modulation and coding scheme (MSC) for the first frequency band.

14. 11. The STA of claim 10, wherein the uplink preference indication for the first frequency band includes at least one of: (i) an indication of an achievable target uplink received power; or (ii) a target uplink received signal strength (RSSI) for the first frequency band.

15. The STA of claim 10, wherein the information indicating the TWT service period in the first frequency band and the TWT service period in the second frequency band is included in a beacon frame transmitted by the AP in the first frequency band.

16. 11. The STA of claim 10, wherein if a payload length is less than a threshold, the STA completes transmission of the payload in a physical layer protocol data unit (PPDU) on the second frequency band.

17. 17. The STA of claim 16, wherein the PPDU indicates that uplink resources in the first frequency band are not required.

18. The transceiver and the processor determining a modulation and coding scheme (MCS) for the first frequency band based on a power headroom derived from a path loss estimated from a downlink broadcast frame received in the first frequency band; receiving a trigger frame indicating at least a size or a location of a resource unit; Selecting the MCS based on the trigger frame The STA of claim 10 further configured to:

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