Dynamic methods and procedures for secondary channel access in WIFI system

Abstract

Systems and methods for enabling usage of remaining bandwidth while a primary portion is occupied, busy or otherwise unavailable. In particular, the present disclosure is directed to implementations for secondary channel access via one or more secondary channels while a primary channel is busy or occupied. In an example, wireless devices may switch to monitor one of their secondary subchannels for physical and virtual carrier sensing when the primary channel is busy. A first device may define and announce one or more anchor channels which may be used as subchannels for which the other devices may perform channel access by using physical and / or virtual carrier sensing. The anchor channels may be used temporarily as the primary channel when the primary channel is busy. In some implementations, the devices may continue monitoring the primary channel, and may switch back to the primary channel when the primary channel becomes available again.

Description

DYNAMIC METHODS AND PROCEDURES FOR SECONDARY CHANNEL ACCESS IN WIFI SYSTEMCROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims the benefit of U.S. Provisional Application No. 63 / 620,813, filed January 13, 2024, the contents of which are incorporated herein by reference.BACKGROUND

[0002] In some implementations of wireless local area network (WLAN) systems with multiple channel widths, a portion (or sometimes the majority) of the bandwidth available to a system (e.g. a basic service set (BSS)) may be wasted, due to medium access by a single station (STA) or an overlapping BSS that operates on only a portion of the available bandwidth. For example, a portion of bandwidth for a first BSS may be busy or may experience interference from an overlapping BSS. This portion may be referred to as a primary channel, and some or all of the remaining bandwidth may be referred to as a secondary channel.SUMMARY

[0003] Aspects of the present disclosure may be directed to implementations of systems and methods for enabling usage of remaining bandwidth while a primary portion is occupied, busy or otherwise unavailable, by transmitters, receivers, or both. In particular, aspects may be directed to implementations for secondary channel access via one or more secondary subchannels while a primary subchannel is busy or occupied. In some implementations, wireless devices (including access points (APs), non-AP stations (STAs), or other wireless transmit / receive units (WTRUs)) may switch to monitor one of their secondary subchannels for physical and virtual carrier sensing when the primary channel is busy.

[0004] In one aspect, a first device, such as an AP, may define and announce one or more anchor channels which may be used as subchannels for which the AP and STAs may perform non-primary channel access (NPCA) by using physical and / or virtual carrier sensing. The anchor channels may be used as the temporary primary channel when the primary channel is busy. In some implementations, the devices may start transmitting on the anchor channel when the physical and / or virtual carrier sensing results determine the wireless media is idle or free from interference. In some implementations, the devices may continue monitoring the primary channel, and may switch back to the primary channel when the primary channel becomes available again.

[0005] In one example, a device / method for use in a wireless local area network (WLAN) station (STA), e.g., an AP STA or a non-AP STA, may include determining, based on a primary channel associated with a first AP being unavailable, thatthe first AP will switch from the primary channel to an anchor channel associated with the first AP. The STA receives, from a second AP, before a timer associated with the first AP expires, a control frame indicating that the anchor channel associated with the first AP is idle. In response to receivingthe control frame, the STA sends, via the anchor channel, a transmission to access the anchor channel. In various aspects, the STA may be the first AP, i.e., an AP STA, or a non-AP STA associated with the first AP. According to various aspects, the first AP and the second AP are associated with a multi-AP group (MAP). In certain aspects, the anchor channel associated with the first AP conforms to a primary channel associated with the second AP. According to various aspects, the control frame may be a short control frame including one of a request to send (RTS), a clear to send (CTS), a buffer status report poll (BSRP) frame, a buffer status report response (BSRR) frame or a trigger frame, having a duration field for setting network allocation vectors (NAVs), set to zero. This enables a STA receiving the control frame on the anchor channel to respond immediately for non-primary channel access on the anchor channel. In one example, the timer associated with the first AP is a synchronization delay timer. In another example, the first AP and the second AP use the same bandwidth.

[0006] According to other aspects of the disclosure, an example STA / method for use in the STA may include receiving, from an AP that the STA is associated with, an indication of anchor channel(s) for nonprimary channel access when a primary channel with the AP is unavailable. The STA determines the primary channel with the AP is unavailable and monitors the indicated anchor channel(s). The STA receives, from the AP on one of the monitored anchor channels, a control frame indicating that the respective anchor channel is idle and a duration that the AP will remain on the anchor channel. In response to receiving the control frame, the STA sends, via the anchor channel, a transmission for anchor channel access. According to some aspects, the STA receives, from the AP on the anchor channel, a transmission opportunity (TXOP) for the STA to transmit or receive on the anchor channel. In one example, the STA then sends, to the AP on the anchor channel during the TXOP, an indication that the STA will remain on the anchor channel following the TXOP, for longer than the duration that the AP indicated it will remain on the anchor channel. In a variation example, prior to sending the indication that the STA will remain on the anchor channel following the TXOP, the STA receives, from the AP on the anchor channel, an indication that the STA should remain of the anchor channel following the TXOP.

[0007] In various implementations, the control frame is one of a request to send (RTS), a clear to send (CTS), a buffer status report poll (BSRP) frame or a trigger frame. In certain aspects, the control frame may have a duration field, which is used by STAs in setting their network allocation vectors (NAVs), set to zero to enable the STA to immediately contend for anchor channel access. In various examples, the anchor channel is a secondary channel of bandwidth of the AP used for channel bonding. In various examples, the anchor channel conforms to, or falls within, a bandwidth of a primary channel of a second AP in a multi-AP group (MAP) with the AP. Additional aspects, features and advantages will become apparent from the detailed embodiments described hereafter.BRIEF DESCRIPTION OF THE DRAWINGS

[0008] A more detailed understanding may be had from the following description, given by way of example in conjunction with the accompanying drawings, wherein like reference numerals in the figures indicate like elements, and wherein:

[0009] FIG. 1A is a system diagram illustrating an example communications system in which one or more disclosed embodiments may be implemented;

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

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

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

[0013] FIG. 2 is a signal flow diagram of secondary channel access using a target wake time, according to some implementations;

[0014] FIG. 3A is a table illustrating an example target wake time element, according to some implementations;

[0015] FIG. 3B is a table illustrating an example target wake time control field, according to some implementations;

[0016] FIG. 3C is a table illustrating an example target wake time individual parameter field, according to some implementations;

[0017] FIG. 4 is a signal diagram illustrating an embodiment of MAP assisted synchronization recovery, according to some implementations;

[0018] FIG. 5 is a signal diagram illustrating an embodiment of switching between primary and anchor channels, according to some implementations; and

[0019] FIG. 6 is a signal diagram illustrating another embodiment of switching between primary and anchor channels, according to some implementations.DETAILED DESCRIPTION

[0020] FIG. 1A is a diagram illustrating an example communications system 100 in which one or more disclosed embodiments may be implemented. The communications system 100 may be a multiple access system that provides content, such as voice, data, video, messaging, broadcast, etc., to multiple wireless users. The communications system 100 may enable multiple wireless users to access such content through the sharing of system resources, including wireless bandwidth. For example, the communications systems 100 may employ one or more channel access methods, such as code division multiple access (CDMA), time division multiple access (TDMA), frequency division multiple access (FDMA), orthogonal FDMA (OFDMA), single-carrier FDMA (SC-FDMA), zero-tail unique-word discrete Fourier transform Spread OFDM (ZT-UW-DFT-S- OFDM), unique word OFDM (UW-OFDM), resource block-filtered OFDM, filter bank multicarrier (FBMC), and the like.

[0021] As shown in FIG. 1A, the communications system 100 may include wireless transmit / receive units (WTRUs) 102a, 102b, 102c, 102d, a radio access network (RAN) 104, a core network (ON) 106, a public switched telephone network (PSTN) 108, the Internet 110, and other networks 112, though itwill be appreciated that the disclosed embodiments contemplate any number of WTRUs, base stations, networks, and / or network elements. Each of the WTRUs 102a, 102b, 102c, 102d may be any type of device configured to operate and / or communicate in a wireless environment By way of example, the WTRUs 102a, 102b, 102c, 102d, any of which may be referred to as a station (STA), may be configured to transmit and / or receive wireless signals and may include a user equipment (UE), a mobile station, a fixed or mobile subscriber unit, a subscription-based unit, a pager, a cellular telephone, a personal digital assistant (PDA), a smartphone, a laptop, a netbook, a personal computer, a wireless sensor, a hotspot or Mi-Fi device, an Internet of Things (loT) device, a watch or other wearable, a head-mounted display (HMD), a vehicle, a drone, a medical device and applications (e.g., remote surgery), an industrial device and applications (e.g., a robot and / or other wireless devices operating in an industrial and / or an automated processing chain contexts), a consumer electronics device, a device operating on commercial and / or industrial wireless networks, and the like. Any of the WTRUs 102a, 102b, 102c and 102d may be interchangeably referred to as a UE.

[0022] The communications systems 100 may also include a base station 114a and / or a base station 114b. Each of the base stations 114a, 114b may be any type of device configured to wirelessly interface with at least one of the WTRUs 102a, 102b, 102c, 102d to facilitate access to one or more communication networks, such as the CN 106, the Internet 110, and / or the other networks 112. By way of example, the base stations 114a, 114b may be a base transceiver station (BTS), a NodeB, an eNode B (eNB), a Home Node B, a Home eNode B, a next generation NodeB, such as a gNode B (gNB), a new radio (NR) NodeB, a site controller, an access point (AP), a wireless router, and the like. While the base stations 114a, 114b are each depicted as a single element, it will be appreciated that the base stations 114a, 114b may include any number of interconnected base stations and / or network elements.

[0023] 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, and the like. The base station 114a and / or the base station 114b may be configured to transmit and / or receive wireless signals on one or more carrier frequencies, which may be referred to as a cell (not shown). These frequencies may be in licensed spectrum, unlicensed spectrum, or a combination of licensed and unlicensed spectrum A cell may provide coverage for a wireless service to a specific geographical area that may be relatively fixed or that may change over time. The cell may further be divided into cell sectors. For example, the cell associated with the base station 114a may be divided into three sectors. Thus, in one embodiment, the base station 114a may include three transceivers, i.e., one for each sector of the cell. In anembodiment, the base station 114a may employ multiple-input multiple output (MIMO) technology and may utilize multiple transceivers for each sector of the cell. For example, beamforming may be used to transmit and / or receive signals in desired spatial directions.

[0024] The base stations 114a, 114b may communicate with one or more of the WTRUs 102a, 102b, 102c, 102d over an air interface 116, which may be any suitable wireless communication link (e.g., radio frequency (RF), microwave, centimeter wave, micrometer wave, infrared (IR), ultraviolet (UV), visible light, etc.). The air interface 116 may be established using any suitable radio access technology (RAT).

[0025] More specifically, as noted above, the communications system 100 may be a multiple access system and may employ one or more channel access schemes, such as CDMA, TDMA, FDMA, OFDMA, SC-FDMA, and the like. For example, the base station 114a in the RAN 104 and the WTRUs 102a, 102b, 102c may implement a radio technology such as Universal Mobile Telecommunications System (UMTS) Terrestrial Radio Access (UTRA), which may establish the air interface 116 using wideband CDMA (WCDMA). WCDMA may include communication protocols such as High-Speed Packet Access (HSPA) and / or Evolved HSPA (HSPA+). HSPA may include High-Speed Downlink (DL) Packet Access (HSDPA) and / or High-Speed Uplink (UL) Packet Access (HSUPA).

[0026] 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).

[0027] In an embodiment, the base station 114a and the WTRUs 102a, 102b, 102c may implement a radio technology such as NR Radio Access , which may establish the air interface 116 using NR.

[0028] In an embodiment, the base station 114a and the WTRUs 102a, 102b, 102c may implement multiple radio access technologies. For example, the base station 114a and the WTRUs 102a, 102b, 102c may implement LTE radio access and NR radio access together, for instance using dual connectivity (DC) principles. Thus, the air interface utilized by WTRUs 102a, 102b, 102c may be characterized by multiple types of radio access technologies and / or transmissions sent to / from multiple types of base stations (e.g , an eNB and a gNB).

[0029] In other embodiments, the base station 114a and the WTRUs 102a, 102b, 102c may implement radio technologies such as IEEE 802.11 (i.e , Wireless Fidelity (WiFi), IEEE 802.16 (i.e., Worldwide Interoperability for Microwave Access (WiMAX)), CDMA2000, CDMA2000 1X, CDMA2000 EV-DO, Interim Standard 2000 (IS-2000), Interim Standard 95 (IS-95), Interim Standard 856 (IS-856), Global System for Mobile communications (GSM), Enhanced Data rates for GSM Evolution (EDGE), GSM EDGE (GERAN), and the like.

[0030] The base station 114b in FIG 1A may be a wireless router, Home Node B, Home eNode B, or access point, for example, and may utilize any suitable RAT for facilitating wireless connectivity in a localized area, such as a place of business, a home, a vehicle, a campus, an industrial facility, an air corridor (e.g., for use by drones), a roadway, and the like. In 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). Inan 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. As shown in FIG. 1A, the base station 114b may have a direct connection to the Internet 110. Thus, the base station 114b may not be required to access the Internet 110 via the CN 106.

[0031] The RAN 104 may be in communication with the CN 106, which may be any type of network configured to provide voice, data, applications, and / or voice over internet protocol (VoIP) services to one or more of the WTRUs 102a, 102b, 102c, 102d. The data may have varying quality of service (QoS) requirements, such as differing throughput requirements, latency requirements, error tolerance requirements, reliability requirements, data throughput requirements, mobility requirements, and the like. The CN 106 may provide call control, billing services, mobile location-based services, pre-paid calling, Internet connectivity, video distribution, etc., and / or perform high-level security functions, such as user authentication. Although not shown in FIG. 1A, it will be appreciated that the RAN 104 and / or the CN 106 may be in direct or indirect communication with other RANs that employ the same RAT as the RAN 104 or a different RAT. For example, in addition to being connected to the RAN 104, which may be utilizing a NR radio technology, the CN 106 may also be in communication with another RAN (not shown) employing a GSM, UMTS, CDMA 2000, WiMAX, E-UTRA, or WiFi radio technology.

[0032] 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 the other networks 112. The PSTN 108 may include circuit-switched telephone networks that provide plain old telephone service (POTS). The Internet 110 may include a global system of interconnected computer networks and devices that use common communication protocols, such as the transmission control protocol (TCP), user datagram protocol (UDP) and / or the internet protocol (IP) in the TCP / IP internet protocol suite. The networks 112 may include wired and / or wireless communications networks owned and / or operated by other service providers. For example, the networks 112 may include another CN connected to one or more RANs, which may employ the same RAT as the RAN 104 or a different RAT.

[0033] 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. 1 A may be configured to communicate with the base station 114a, which may employ a cellularbased radio technology, and with the base station 114b, which may employ an IEEE 802 radio technology.

[0034] FIG. 1 B is a system diagram illustrating an example WTRU 102. As shown in FIG. 1B, the WTRU 102 may include a processor 118, a transceiver 120, a transmit / receive element 122, a speaker / microphone 124, a keypad 126, a display / touchpad 128, non-removable memory 130, removable memory 132, a power source 134, a global positioning system (GPS) chipset 136, and / or other peripherals 138, among others. It willbe appreciated that the WTRU 102 may include any sub-combination of the foregoing elements while remaining consistent with an embodiment.

[0035] The processor 118 may be a general purpose processor, a special purpose processor, a conventional processor, a digital signal processor (DSP), a plurality of microprocessors, one or more microprocessors in association with a DSP core, a controller, a microcontroller, Application Specific Integrated Circuits (ASICs), Field Programmable Gate Arrays (FPGAs), any other type of integrated circuit (IC), a state machine, and the like. The processor 118 may perform signal coding, data processing, power control, input / output processing, and / or any other functionality that enables the WTRU 102 to operate in a wireless environment. The processor 118 may be coupled to the transceiver 120, which may be coupled to the transmit / receive element 122. While FIG. 1 B 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.

[0036] The transmit / receive element 122 may be configured to transmit signals to, or receive signals from, a base station (e.g., the base station 114a) over the air interface 116. For example, in 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 IR, UV, or visible light signals, for example. In yet another embodiment, the transmit / receive element 122 may be configured to transmit and / or receive both RF and light signals. It will be appreciated that the transmit / receive element 122 may be configured to transmit and / or receive any combination of wireless signals.

[0037] Although the transmit / receive element 122 is depicted in FIG. 1 B 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.

[0038] The transceiver 120 may be configured to modulate the signals that are to be transmitted by the transmit / receive element 122 and to demodulate the signals that are received by the transmit / receive element 122. As noted above, the WTRU 102 may have multi-mode capabilities. Thus, the transceiver 120 may include multiple transceivers for enabling the WTRU 102 to communicate via multiple RATs, such as NR and IEEE 802.11 , for example.

[0039] The processor 118 of the WTRU 102 may be coupled to, and may receive user input data from, the speaker / microphone 124, the keypad 126, and / or the display / touchpad 128 (e.g., a liquid crystal display (LCD) display unit or organic light-emitting diode (OLED) display unit) The processor 118 may also output user data to the speaker / microphone 124, the keypad 126, and / or the display / touchpad 128. In addition, the processor 118 may access information from, and store data in, any type of suitable memory, such as the non-removable memory 130 and / or the removable memory 132. The non-removable memory 130 may include random-access memory (RAM), read-only memory (ROM), a hard disk, or any other type of memory storage device. The removable memory 132 may include a subscriber identity module (SIM) card, a memory stick, a secure digital(SD) memory card, and the like. In other embodiments, the processor 118 may access information from, and store data in, memory that is not physically located on the WTRU 102, such as on a server or a home computer (not shown).

[0040] The processor 118 may receive power from the power source 134, and may be configured to distribute and / or control the power to the other components in the WTRU 102. The power source 134 may be any suitable device for powering the WTRU 102. For example, the power source 134 may include one or more dry cell batteries (e.g., nickel-cadmium (NiCd), nickel-zinc (NiZn), nickel metal hydride (NiMH), lithium-ion (Li- ion), etc.), solar cells, fuel cells, and the like.

[0041] The processor 118 may also be coupled to the GPS chipset 136, which may be configured to provide location information (e.g., longitude and latitude) regarding the current location of the WTRU 102. In addition to, or in lieu of, the information from the GPS chipset 136, the WTRU 102 may receive location information over the air interface 116 from a base station (e.g., base stations 114a, 114b) and / or determine its location based on the timing of the signals being received from two or more nearby base stations. It will be appreciated that the WTRU 102 may acquire location information by way of any suitable location-determination method while remaining consistent with an embodiment

[0042] The processor 118 may further be coupled to other peripherals 138, which may include one or more software and / or hardware modules that provide additional features, functionality 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 photographs and / or video), a universal serial bus (USB) port, a vibration device, a television transceiver, a hands free headset, a Bluetooth® module, a frequency modulated (FM) radio unit, a digital music player, a media player, a video game player module, an Internet browser, a Virtual Reality and / or Augmented Reality (VR / AR) device, an activity tracker, and the like. The peripherals 138 may include one or more sensors. The sensors may be one or more of a gyroscope, an accelerometer, a hall effect sensor, a magnetometer, an orientation sensor, a proximity sensor, a temperature sensor, a time sensor; a geolocation sensor, an altimeter, a light sensor, a touch sensor, a magnetometer, a barometer, a gesture sensor, a biometric sensor, a humidity sensor and the like.

[0043] The WTRU 102 may include a full duplex radio for which transmission and reception of some or all of the signals (e g., associated with particular subframes for both the UL (e.g., for transmission) and DL (e.g., for reception) may be concurrent and / or simultaneous. The full duplex radio may include an interference management unit to reduce and or substantially eliminate self-interference via either hardware (e.g., a choke) or signal processing via a processor (e.g., a separate processor (not shown) or via processor 118). In an embodiment, the WTRU 102 may include a half-duplex radio for which transmission and reception of some or all of the signals (e.g., associated with particular subframes for either the UL (e g., for transmission) or the DL (e g., for reception)).

[0044] FIG. 1C is a system diagram illustrating the RAN 104 and the CN 106 according to an embodiment. As noted above, the RAN 104 may employ an E-UTRA radio technology to communicate with the WTRUs 102a, 102b, 102c over the air interface 116. The RAN 104 may also be in communication with the CN 106.

[0045] The RAN 104 may include eNode-Bs 160a, 160b, 160c, though it will be appreciated that the RAN 104 may include any number of eNode-Bs while remaining consistent with an embodiment. The eNode-Bs 160a, 160b, 160c may each include one or more transceivers for communicating with the WTRUs 102a, 102b, 102c over the air interface 116. In one embodiment, the eNode-Bs 160a, 160b, 160c may implement MIMO technology. Thus, the eNode-B 160a, for example, may use multiple antennas to transmit wireless signals to, and / or receive wireless signals from, the WTRU 102a.

[0046] Each of the eNode-Bs 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, and the like. As shown in FIG. 1 C, the eNode-Bs 160a, 160b, 160c may communicate with one another over an X2 interface.

[0047] The CN 106 shown in FIG. 1C may include a mobility management entity (MME) 162, a serving gateway (SGW) 164, and a packet data network (PDN) gateway (PGW) 166. While 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.

[0048] The MME 162 may be connected to each of the eNode-Bs 162a, 162b, 162c in the RAN 104 via an S1 interface and may serve as a control node. For example, the MME 162 may be responsible for authenticating users of the WTRUs 102a, 102b, 102c, bearer activation / deactivation, selecting a particular serving gateway during an initial attach of the WTRUs 102a, 102b, 102c, and the like. The MME 162 may provide a control plane function for switching between the RAN 104 and other RANs (not shown) that employ other radio technologies, such as GSM and / or WCDMA

[0049] The SGW 164 may be connected to each of the eNode Bs 160a, 160b, 160c in the RAN 104 via the S1 interface. The SGW 164 may generally route and forward user data packets to / from the WTRUs 102a, 102b, 102c. The SGW 164 may perform other functions, such as anchoring user planes during inter-eNode B handovers, triggering paging when DL data is available for the WTRUs 102a, 102b, 102c, managing and storing contexts of the WTRUs 102a, 102b, 102c, and the like.

[0050] The SGW 164 may be connected to the PGW 166, which may provide the WTRUs 102a, 102b, 102c with access to packet-switched networks, such as the Internet 110, to facilitate communications between the WTRUs 102a, 102b, 102c and IP-enabled devices.

[0051] The CN 106 may facilitate communications with other networks For example, the CN 106 may provide the WTRUs 102a, 102b, 102c with access to circuit-switched networks, such as the PSTN 108, to facilitate communications between the WTRUs 102a, 102b, 102c and traditional land-line communications devices. For example, the CN 106 may include, or may communicate with, an IP gateway (e.g., an IP multimedia subsystem (IMS) server) that serves as an interface between the CN 106 and the PSTN 108. Inaddition, the CN 106 may provide the WTRUs 102a, 102b, 102c with access to the other networks 112, which may include other wired and / or wireless networks that are owned and / or operated by other service providers.

[0052] Although the WTRU is described in FIGS. 1A-1 D as a wireless terminal, it is contemplated that in certain representative embodiments that such a terminal may use (e.g., temporarily or permanently) wired communication interfaces with the communication network.

[0053] In representative embodiments, the other network 112 may be a WLAN.

[0054] 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 or an interface to a Distribution System (DS) or another type of wired / wireless network that carries traffic in to and / or out of the BSS. Traffic to STAs that originates from outside the BSS may arrive through the AP and may be delivered to the STAs. Traffic originating from STAs to destinations outside the BSS may be sent to the AP to be delivered to respective destinations. Traffic between STAs within the BSS may be sent through the AP, for example, where the source STA may send traffic to the AP and the AP may deliver the traffic to the destination STA The traffic between STAs within a BSS may be considered and / or referred to as peer-to-peer traffic. The peer-to- peer traffic may be sent between (e.g., directly between) the source and destination STAs with a direct link setup (DLS). In certain representative embodiments, the DLS may use an 802.11e DLS or an 802.11z tunneled DLS (TDLS). A WLAN using an Independent BSS (IBSS) mode may not have an AP, and the STAs (e.g., all of the STAs) within or using the IBSS may communicate directly with each other. The IBSS mode of communication may sometimes be referred to herein as an “ad-hoc” mode of communication.

[0055] When using the 802.11 ac infrastructure mode of operation or a similar mode of operations, the AP may transmit a beacon on a fixed channel, such as a primary channel. The primary channel may be a fixed width (e.g., 20 MHz wide bandwidth) or a dynamically set width. The primary channel may be the operating channel of the BSS and may be used by the STAs to establish a connection with the AP. In certain representative embodiments, Carrier Sense Multiple Access with Collision Avoidance (CSMA / CA) may be implemented, for example in 802.11 systems. For CSMA / CA, the STAs (e.g., every STA), including the AP, may sense the primary channel. If the primary channel is sensed / detected and / or determined to be busy by a particular STA, the particular STA may back off. One STA (e.g., only one station) may transmit at any given time in a given BSS.

[0056] High Throughput (HT) STAs may use a 40 MHz wide channel for communication, for example, via a combination of the primary 20 MHz channel with an adjacent or nonadjacent 20 MHz channel to form a 40 MHz wide channel.

[0057] Very High Throughput (VHT) STAs may support 20MHz, 40 MHz, 80 MHz, and / or 160 MHz wide channels The 40 MHz, and / or 80 MHz, channels may be formed by combining contiguous 20 MHz channels. A 160 MHz channel may be formed by combining 8 contiguous 20 MHz channels, or by combining two noncontiguous 80 MHz channels, which may be referred to as an 80+80 configuration. For the 80+80 configuration, the data, after channel encoding, may be passed through a segment parser that may divide the data into twostreams. Inverse Fast Fourier Transform (IFFT) processing, and time domain processing, may be done on each stream separately The streams may be mapped on to the two 80 MHz channels, and the data may be transmitted by a transmitting STA. At the receiver of the receiving STA, the above described operation for the 80+80 configuration may be reversed, and the combined data may be sent to the Medium Access Control (MAC).

[0058] Sub 1 GHz modes of operation are supported by 802.11 af and 802.11 ah. The channel operating bandwidths, and carriers, are reduced in 802.11 af and 802.11ah relative to those used in 802.11n, and 802.11ac. 802.11 af supports 5 MHz, 10 MHz, and 20 MHz bandwidths in the TV White Space (TVWS) spectrum, and 802.11 ah supports 1 MHz, 2 MHz, 4 MHz, 8 MHz, and 16 MHz bandwidths using non-TVWS spectrum. According to a representative embodiment, 802.11 ah may support Meter Type Control / Machine- Type Communications (MTC), such as MTC devices in a macro coverage area. MTC devices may have certain capabilities, for example, limited capabilities including support for (e.g , only support for) certain and / or limited bandwidths The MTC devices may include a battery with a battery life above a threshold (e.g., to maintain a very long battery life).

[0059] WLAN systems, which may support multiple channels, and channel bandwidths, such as 802 11 n, 802.11ac, 802.11af, and 802.11 ah, include a channel which may be designated as the primary channel. The primary channel may have a bandwidth equal to the largest common operating bandwidth supported by all STAs in the BSS. The bandwidth of the primary channel may be set and / or limited by a STA, from among all STAs in operating in a BSS, which supports the smallest bandwidth operating mode. In the example of 802.11ah, the primary channel may be 1 MHz wide for STAs (e.g., MTC type devices) that support (e.g., only support) a 1 MHz mode, even if the AP, and other STAs in the BSS support 2 MHz, 4 MHz, 8 MHz, 16 MHz, and / or other channel bandwidth operating modes. Carrier sensing and / or Network Allocation Vector (NAV) settings may depend on the status of the primary channel. If the primary channel is busy, for example, due to a STA (which supports only a 1 MHz operating mode) transmitting to the AP, all available frequency bands may be considered busy even though a majority of the available frequency bands remains idle.

[0060] In the United States, the available frequency bands, which may be used by 802.11 ah, are from 902 MHz to 928 MHz. In Korea, the available frequency bands are from 917.5 MHz to 923.5 MHz. In Japan, the available frequency bands are from 916.5 MHz to 927.5 MHz. The total bandwidth available for 802.11ah is 6 MHz to 26 MHz depending on the country code.

[0061] FIG. 1 D is a system diagram illustrating the RAN 104 and the CN 106 according to an embodiment. As noted above, the RAN 104 may employ an NR radio technology to communicate with the WTRUs 102a, 102b, 102c over the air interface 116. The RAN 104 may also be in communication with the CN 106.

[0062] The RAN 104 may include gNBs 180a, 180b, 180c, though it will be appreciated that the RAN 104 may include any number of gNBs while remaining consistent with an embodiment. The gNBs 180a, 180b, 180c may each include one or more transceivers for communicating with the WTRUs 102a, 102b, 102c over the air interface 116. In one embodiment, the gNBs 180a, 180b, 180c may implement MIMO technology. For example,gNBs 180a, 108b may utilize beamforming to transmit signals to and / or receive signals from the gNBs 180a, 180b, 180c. Thus, the gNB 180a, for example, may use multiple antennas to transmit wireless signals to, and / or receive wireless signals from, the WTRU 102a. In an embodiment, the gNBs 180a, 180b, 180c may implement carrier aggregation technology. For example, the gNB 180a may transmit multiple component carriers to the WTRU 102a (not shown). A subset of these component carriers may be on unlicensed spectrum while the remaining component carriers may be on licensed spectrum. In an embodiment, the gNBs 180a, 180b, 180c may implement Coordinated Multi-Point (CoMP) technology. For example, WTRU 102a may receive coordinated transmissions from gNB 180a and gNB 180b (and / or gNB 180c).

[0063] The WTRUs 102a, 102b, 102c may communicate with gNBs 180a, 180b, 180c using transmissions associated with a 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 gNBs 180a, 180b, 180c using subframe or transmission time intervals (TTIs) of various or scalable lengths (e.g., containing a varying number of OFDM symbols and / or lasting varying lengths of absolute time).

[0064] The gNBs 180a, 180b, 180c may be configured to communicate with the WTRUs 102a, 102b, 102c in a standalone configuration and / or a non-standalone configuration. In the standalone configuration, WTRUs 102a, 102b, 102c may communicate with gNBs 180a, 180b, 180c without also accessing other RANs (e.g., such as eNode-Bs 160a, 160b, 160c). In the standalone configuration, WTRUs 102a, 102b, 102c may utilize one or more of gNBs 180a, 180b, 180c as a mobility anchor point. In the standalone configuration, WTRUs 102a, 102b, 102c may communicate with gNBs 180a, 180b, 180c using signals in an unlicensed band. In a non-standalone configuration WTRUs 102a, 102b, 102c may communicate with / connect to gNBs 180a, 180b, 180c while also communicating with / connecting to another RAN such as eNode-Bs 160a, 160b, 160c. For example, WTRUs 102a, 102b, 102c may implement DC principles to communicate with one or more gNBs 180a, 180b, 180c and one or more eNode-Bs 160a, 160b, 160c substantially simultaneously. In the non- standalone configuration, eNode-Bs 160a, 160b, 160c may serve as a mobility anchor for WTRUs 102a, 102b, 102c and gNBs 180a, 180b, 180c may provide additional coverage and / or throughput for servicing WTRUs 102a, 102b, 102c.

[0065] Each of the gNBs 180a, 180b, 180c may be associated with a particular cell (not shown) and may be configured to handle radio resource management decisions, handover decisions, scheduling of users in the UL and / or DL, support of network slicing, DC, interworking between NR and E-UTRA, routing of user plane data towards User Plane Function (UPF) 184a, 184b, routing of control plane information towards Access and Mobility Management Function (AMF) 182a, 182b and the like. As shown in FIG. 1D, the gNBs 180a, 180b, 180c may communicate with one another over an Xn interface.

[0066] The CN 106 shown in FIG. 1 D 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.

[0067] 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 serve as a control node. For example, the AMF 182a, 182b may be responsible for authenticating users of the WTRUs 102a, 102b, 102c, support for network slicing (e.g., handling of different protocol data unit (PDU) sessions with different requirements), selecting a particular SMF 183a, 183b, management of the registration area, termination of non-access stratum (NAS) signaling, mobility management, and the like. Network slicing may be used by the AMF 182a, 182b in order to customize CN support for WTRUs 102a, 102b, 102c based on the types of services being utilized WTRUs 102a, 102b, 102c. For example, different network slices may be established for different use cases such as services relying on ultra-reliable low latency (URLLC) access, services relying on enhanced massive mobile broadband (eMBB) access, services for MTC access, and the like 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.

[0068] The SMF 183a, 183b may be connected to an AMF 182a, 182b in the CN 106 via an N11 interface. The SMF 183a, 183b may also be connected to a UPF 184a, 184b in the CN 106 via an N4 interface. The SMF 183a, 183b may select and control the UPF 184a, 184b and configure the routing of traffic through the UPF 184a, 184b. The SMF 183a, 183b may perform other functions, such as managing and allocating UE IP address, managing PDU sessions, controlling policy enforcement and QoS, providing DL data notifications, and the like. A PDU session type may be IP-based, non-IP based, Ethernet-based, and the like.

[0069] The UPF 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 communications between the WTRUs 102a, 102b, 102c and IP-enabled devices. The UPF 184, 184b may perform other functions, such as routing and forwarding packets, enforcing user plane policies, supporting multi-homed PDU sessions, handling user plane QoS, buffering DL packets, providing mobility anchoring, and the like.

[0070] The CN 106 may facilitate communications with other networks For example, the CN 106 may include, or may communicate with, an IP gateway (e.g., an IP multimedia subsystem (IMS) server) that serves as an interface between the CN 106 and the PSTN 108. In addition, the CN 106 may provide the WTRUs 102a, 102b, 102c with access to the other networks 112, which may include other wired and / or wireless networks that are owned and / or operated by other service providers In one embodiment, the WTRUs 102a, 102b, 102c may be connected to a local DN 185a, 185b through the UPF 184a, 184b via the N3 interface to the UPF 184a, 184b and an N6 interface between the UPF 184a, 184b and the DN 185a, 185b.

[0071] In view of FIGs. 1A-1 D, and the corresponding description of FIGs. 1A-1 D, one or more, or all, of the functions described herein with regard to one or more of: WTRU 102a-d, Base Station 114a-b, eNode-B 160a-c, MME 162, SGW 164, PGW 166, gNB 180a-c, AMF 182a-b, UPF 184a-b, SMF 183a-b, DN 185a-b,and / or any other device(s) 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 network and / or WTRU functions.

[0072] The emulation devices may be designed to implement one or more tests of other devices in a lab environment and / or in an operator network environment. For example, the one or more emulation devices may perform the one or more, or all, functions while being fully or partially implemented and / or deployed as part of a wired and / or wireless communication network in order to test other devices within the communication network. The one or more emulation devices may perform the one or more, or all, functions while being temporarily implemented / deployed as part of a wired and / or wireless communication network The emulation device may be directly coupled to another device for purposes of testing and / or performing testing using over-the-air wireless communications.

[0073] The one or more emulation devices may perform the one or more, including all, functions while not being implemented / deployed as part of a wired and / or wireless communication network. For example, the emulation devices may be utilized in a testing scenario in a testing laboratory and / or a non-deployed (e.g., testing) wired and / or wireless communication network in order to implement testing of one or more components. The one or more emulation devices may be test equipment. Direct RF coupling and / or wireless communications via RF circuitry (e.g., which may include one or more antennas) may be used by the emulation devices to transmit and / or receive data.

[0074] As described in IEEE Std 802.11 ™-2020: Wireless Local Area Network (WLAN) Medium Access Control (MAC) and Physical Layer (PHY) Specifications, incorporated herein by reference, a WLAN in Infrastructure Basic Service Set (BSS) mode has an Access Point (AP), i.e., AP STA, for the BSS and one or more stations (STAs), i.e., non-AP 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 in and out of the BSS. Traffic to STAs that originates from outside the BSS arrives through the AP and is delivered to the STAs T raffic originating from STAs to destinations outside the BSS is sent to the AP to be delivered to the respective destinations. Traffic between STAs within the BSS may also be sent through the AP where the source STA sends traffic to the AP and the AP delivers the traffic to the destination STA. Such traffic between STAs within a BSS is really peer-to-peer traffic. Such peer-to-peer traffic may also be sent directly between the source and destination STAs with a direct link setup (DLS) using an 802.11e DLS or an 802.11z tunneled DLS (TDLS) A WLAN using an Independent BSS (IBSS) mode has no AP, and / or STAs, communicating directly with each other. This mode of communication is referred to as an “ad-hoc” mode of communication.

[0075] In an infrastructure mode (e.g. BSS infrastructure mode), an AP may transmit a beacon on a fixed channel, usually the primary channel. In an example, this channel may be 20 MHz wide, and referred to as the operating channel of the BSS. In some implementations, this channel is also used by the STAs to establish a connection with the AP. In some implementations, the fundamental channel access mechanism in an 802.11system is Carrier Sense Multiple Access with Collision Avoidance (CSMA / CA). In this mode of operation, every STA, including the AP, will sense the occupancy or vacancy of the primary channel. If the channel is detected to be busy, the STA backs off. Hence only one STA may transmit at any given time in a given BSS.

[0076] In 802.11n, High Throughput (HT) STAs may also use a 40 MHz wide channel for communication. This may be achieved by combining the primary 20 MHz channel, with an adjacent 20 MHz channel to form a 40 MHz wide contiguous channel.

[0077] In 802.11 ac, described in IEEE P802 11 ax™ / D8.0: Wireless LAN Medium Access Control (MAC) and Physical Layer (PHY) Specifications and incorporated by reference herein, Very High Throughput (VHT) STAs may support 20MHz, 40 MHz, 80 MHz and 160 MHz wide channels. 40 MHz and 80 MHz channels may be formed by combining contiguous 20 MHz channels similar to 802.11 n described above Combining lower bandwidth channels to create larger bandwidth channels is sometimes referred to as channel bonding. A 160 MHz channel may be formed either by combining 8 contiguous 20 MHz channels, or by combining two noncontiguous 80 MHz channels, this may also be referred to as an 80+80 configuration. For the 80+80 configuration, in some implementations the data at the transmitter, after channel encoding, is passed through a segment parser that divides it into two streams. Inverse fast Fourier transform (IFFT) and time domain processing are done on each stream separately. The streams are then mapped on to the two channels, and the data is transmitted. At the receiver, this mechanism is reversed, and the combined data is sent to the MAC layer.

[0078] Sub 1 GHz modes of operation are supported by 802.11 af, and 802.11 ah. For these specifications the channel operating bandwidths, and carriers, are reduced relative to those used in 802.11n and 802.11 ac. 802.11 af supports 5 MHz, 10 MHz and 20 MHz bandwidths in the TV White Space (TVWS) spectrum, and 802.11ah supports 1 MHz, 2 MHz, 4 MHz, 8 MHz and 16 MHz bandwidths using non-TVWS spectrum. A possible use case for 802.11 ah is support for Meter Type Control (MTC) devices in a macro coverage area. MTC devices may have limited capabilities including only support for limited bandwidths, but also may include a requirement for a very long battery life.

[0079] WLAN systems which support multiple channels and channel widths, such as 802.11n, 802.11 ac, 802.11 af and / or 802.11 ah, include a channel which is designated as the primary channel. The primary channel may, but not necessarily, have a bandwidth equal to the largest common operating bandwidth supported by all STAs in the BSS. The bandwidth of the primary channel is therefore limited by the STA, which supports the smallest bandwidth operating mode of all STAs operating in a BSS. In the example of 802.11 ah, the primary channel may be 1 MHz wide if there are STAs (e.g MTC type devices) that only support a 1 MHz mode even if the AP, and other STAs in the BSS, may support a 2 MHz, 4 MHz, 8 MHz, 16 MHz or other channel bandwidth operating modes. In many implementations, carrier sensing and NAV settings depend on the status of the primary channel; i.e., if the primary channel is busy, for example, due to a STA supporting only a 1 MHz operating mode is transmitting to the AP, then the entire available frequency bands are considered busy even though majority of it stays idle and available.

[0080] In the United States, the available frequency bands which may be used by 802.11 ah are from 902 MHz to 928 MHz. In Korea it is from 917.5 MHz to 923.5 MHz; and in Japan, it is from 916 5 MHz to 9275 MHz. The total bandwidth available for 802.11 ah is 6 MHz to 26 MHz depending on the country code. Other frequency bands and channel widths may be utilized, depending on application and implementation.

[0081] As mentioned previously, in some implementations of wireless local area network (WLAN) systems with multiple channel widths, a portion (or sometimes the majority) of the bandwidth available to a system (e.g. a basic service set (BSS)) may be wasted due to medium access by a single station (STA) or an overlapping BSS that operates on only a portion of the available bandwidth For example, a portion of bandwidth for a first BSS may be busy or may experience interference from an overlapping BSS. This portion may be referred to as a primary channel, and some or all of the remaining bandwidth may be referred to as a secondary channel. In WLANs, a "primary channel" may generally refer to the main frequency band used for wireless communication, while a "secondary channel" is typically one or more additional bands paired with the primary channel to create a wider bandwidth, which generally is used to increase data throughput by "bonding" channels together. Essentially, the primary channel handles control functions and is always active, while the secondary channels are used for data transmission when needed and requires compatible capabilities between devices to function effectively.

[0082] Some methods of secondary channel access (SCA) have been attempted, with various drawbacks. For example, in subchannel selective transmission (SST) implementations, such as that used with 802.11 ax, a STA may transmit and receive on a secondary channel. A high efficiency (HE) SST non-AP STA and a HE SST AP may set up SST operation by negotiating a trigger enabled Target Wake Time (TWT) using individual TWT agreements.

[0083] Referring to FIG. 2 an example method 200 of individual TWT operation is shown where STA1 sends a TWT request 205 and receives a TWT response 210 from the AP to set a trigger-enabled TWT service period 215 where STA1 should be awake and ready to receive and / or transmit. Referring to FIGs. 3A-3B, an example of a TWT element 300 with corresponding Control field 320 and TWT Parameter Info field 340 used in this process is shown.

[0084] Referring to FIG. 3B an example of the TWT Control field 320 is shown, where a Negotiation Type subfield 322 may include a broadcast type subfield (not shown), which may indicate whether the TWT element 300 is for broadcast TWT or individual TWT. If the broadcast type subfield of the Negotiation Type subfield 322 is = 0, the TWT element is for individual TWT, and then only one individual TWT Parameter Info field 340 set is contained in the TWT element 300.

[0085] In FIG. 3C, an example of an Individual TWT Parameter Info field 340 is shown, which includes a TWT Channel subfield 342. The TWT Channel subfield 342 indicates the subchannels the STA may need to monitor during the negotiated TWT SP. The SST operation allows a non-AP STA to operate on a secondary 20MHz subchannel or a secondary 80MHz subchannel in the negotiated TWT SP. The non-AP STA shall be available at the TWT start time and shall not access the medium in the subchannel using distributed coordinatedfunction (DCF) or enhanced distributed channel access function (EDCAF). Instead, the channel access for the non-AP STA during the SST operation is trigger-based, meaning that the AP grants uplink resources for the non-AP STAs to perform uplink transmission. A non-AP STA may include a Channel Switch Timing element in (Re)Association Request frames it transmits to an AP to indicate the time required by the STA to switch between different subchannels.

[0086] Embodiments disclosed herein may be directed to implementations of systems and methods for enabling usage of remaining bandwidth while a primary portion is occupied, busy or otherwise unavailable, by transmitters, receivers, or both. In particular, embodiments are disclosed for secondary channel access (SCA) via one or more secondary subchannels while a primary subchannel is busy or occupied In some implementations, wireless devices (including access points (APs), non-AP stations (STAs), or other wireless transmit / receive units (WTRUs)) may switch to monitor one of their secondary (sub)channels for physical and virtual carrier sensing when the primary channel is busy

[0087] In one example embodiment, a first device, such as an AP, may define and announce one or more (sub)channels, referred to herein as anchor channels, which may be used as (sub)channels for which the AP and STAs may perform channel access by using physical and / or virtual carrier sensing. In various examples, the anchor channels may be used as a temporary primary channel when the primary channel is busy. This may be referred to as non-primary channel access (NPCA). In some examples, an anchor channel, which may be referred to interchangeably herein as an NPCA primary channel, may use a 20MHz resolution or 40MHz resolution. An anchor channel / NPCA primary channel may differ from a primary channel as is described substantially in paragraphs above. For example, the primary channel may refer to a 20MHz channel in which a CCA / NAV operation is usually performed. Additionally, or alternatively, a primary channel may refer to a channel in which one or more STAs are configured to carry out CCA / NAV operation by default By contrast, the terms anchor channel and / or NPCA primary channel may refer to a 20MHz channel in which one or more STAs are configured to perform CCA / NAV when the primary channel is occupied. An anchor channel and / or NPCA primary channel may be considered a secondary channel.

[0088] In some implementations, the devices may start transmitting on an anchor channel when the physical and / or virtual carrier sensing results determine the wireless media is idle and / or free from interference. In some implementations, the devices may continue monitoring the primary channel, and may switch back to the primary channel when the primary channel becomes available again

[0089] In embodiments which may use multi-link operation (MLO), the support of secondary channel access (SCA) may be per link, meaning a first STA affiliated with a STA multi-link device (MLD) may support SCA while another STA affiliated with the same STA MLD may not support SCA. Alternatively, in another implementation, the support of SCA may be per device. In such implementations, if a STA MLD supports the SCA operation, then all STAs affiliated with the STA MLD may support the SCA. If a STA MLD does not support the SCA operation, then all STAs affiliated with the STA MLD may not support the SCA.

[0090] In some example embodiments, the anchor channel may have 20MHz resolution or 40MHz resolution. In some implementations, the secondary channel may have 20MHz, 40MHz, 60MHz, 80MHz or 160MHz resolution. The access to a secondary channel may be through the access of an anchor channel. Accordingly, in some implementations, anchor channel access may refer to a secondary channel access (SCA). In one example, the AP may be operating on a 320MHz channel and its primary 20MHz subchannel is within its primary 160MHz subchannel. In one example, one or more 20MHz subchannels in the secondary 160MHz channel may be selected as an anchor channel. In one example, a 20M Hz subchannel in the secondary 80M Hz subchannel, a 20MHz subchannel in the third 80MHz and / or a 20MHz subchannel in the fourth 80MHz subchannel may be selected and used as anchor channels.

[0091] The following embodiments primarily refer to AP STAs and non-AP STAs. However, implementations of these systems and methods may apply equally to AP MLDs and / or non-AP STA MLDs, as well as APs affiliated with an AP MLD and non-AP STAs affiliated with a non-AP STA MLD or any combination of the foregoing.

[0092] Existing network allocation vector (NAV) setting methods are typically not related to the bandwidth. For example, a STA may receive a PPDU. The STA may read the SIG field or the MAC header to acquire a transmission opportunity (TXOP) Duration field or the Duration field to set a NAV. Accordingly, the NAV setting is not related to any particular channel or subchannel. However, with a primary / anchor channel switch, the STA may need to know if the NAV setting is for the primary channel, the anchor channel or both. Accordingly, the STAs / APs may need a subchannel-based NAV setting capability. If the physical layer protocol data unit (PPDU) that triggers the primary / anchor channel switch is an intra-BSS PPDU, then the STA may check the bandwidth (BW) field and Punctured Channel Indication in the SIG field to determine the subchannels for which the NAV may be related. If the PPDU that triggers the primary / anchor channel switch is an inter-BSS downlink (DL) PPDU, the STA may check the basic service set identifier (BSSID) field or the transmitter address (TA) in the MAC header field to determine which AP transmitted the PPDU. If the STA received a Beacon frame from the AP (the inter-BSS AP which is either the transmitter or receiver of the PPDU) before, the STA may know the operation channel and primary channel of the BSS. Using this information or portions of this information together with the BW field in the SIG field of the PPDU, the STA may be able to know on which subchannels the PPDU may be transmitted If the PPDU is an inter-BSS uplink (UL) PPDU, the STA may check the BSSID field or the receiver address (RA) in the MAC header field to determine the AP which is the receiver of the PPDU. Alternatively, or additionally, the STA may detect if it receives any energy on the anchor channel when it receives the PPDU. In this way, the STA may know if the NAV is set also for the anchor channel The following discussion may apply equally to implementations in which the NAV is set on the primary channel, the anchor channel, or both the primary channel and the anchor channel. For example, when the NAV is set on the primary channel, the NAV may be set only on the primary channel and not on the anchor or secondary channel.

[0093] In some example embodiments, after a device (either an AP or a STA) switches to an anchor channel, it may access the anchor channel using one or more of the following procedures. In some modes,both AP STAs and non-AP STAs may be allowed to use CSMA / CA to access the secondary channel. In another mode, an AP may perform anchor channel access and non-AP STAs may need to wait for the AP to transmit a trigger for uplink transmission. If an AP has an additional radio or RF chain, it may use the radio or RF chain to monitor the anchor channel or the next anchor channel to which the AP may switch. The AP may determine under which condition or conditions it may use the radio / RF chain to monitor the anchor channel For example, in some implementations, if the AP notices a neighbouring BSS is operating on the same operating channel or the same primary channel, and the activity from the neighbouring BSS is frequent, then the AP may use the additional radio / RF chain to monitor the anchor channel. The AP may have updated NAV settings on the anchor channel and the AP may need to obey the NAV on the anchor channel when it switches to it. If the AP does not have an updated NAV setting on the anchor channel, it may need to monitor the anchor channel and perform channel access following one or more of these rules:(i) The AP may start a MediumSyncDelay timer (or other named timer) right after it switches to the anchor channel, and the AP may try to contend or obtain priority for transmitting via the medium on the anchor channel when the MediumSyncDelay timer reaches 0, if the AP has not detected or does not detect any transmission from another WiFi device on the anchor channel; and(ii) If the AP receives a PPDU with valid NAV information on the anchor channel the AP may try to contend or obtain priority for transmitting via the medium after the NAV duration on the anchor channel.

[0094] In some implementations, the secondary access may always start with a control frame exchange, e.g., using a short frame such as a request-to-send (RTS) / clear-to-send (CTS) exchange, multi-user (MU)- RTS / CTS exchange, buffer status report poll (BSRP)Zbuffer status report (BSR) exchange, trigger frame / UL response exchange, new control frames (e.g. frames that include channel characteristics of the anchor or other such information), etc. The control frame exchange enables polling of non-AP STAs so that the AP knows if the non-AP STA is monitoring the anchor channel before the real data transmissions. If the AP does not receive a response from a non-AP STA, the AP knows that STA may not be available for transmissions and receptions via the anchor channel.

[0095] In some implementations, APs with different primary operation channels may form a multiple AP (MAP) group and master basic service set (M-BSS). The APs may negotiate to help each other for quicker medium synchronization recovery. For example, in an AP to AP transmission / negotiation, all the APs in the MAP group may indicate if they agree to provide a MAP assisted synchronization recovery procedure. APs which agree to provide MAP assisted synchronization recovery procedure may follow the procedures illustrated in the FIG. 4 signal diagram 400.

[0096] In the FIG. 4 example network diagram 400 is shown where AP1 and AP2 are in a MAP group. In this example, APTs anchor channel 410 is part of AP2’s primary 80MHz channel 450. AP1 may determine that it may switch from its primary channel 405 to an anchor channel 410 by using the procedure described herein. AP1 may not have updated NAV information on the anchor channel 410 and thus it may need to monitor the anchor channel 410 until its MediumSyncDelay timer 420 reaches 0 (provided it does not receive any PPDUon the anchor channel while monitoring the channel) In the meantime, AP2 may transmit one or more short control frames 460 on its primary channel (e.g., primary 80MHz channel shown in darkened slots of AP2’s bandwidth 450), e.g., using non-high throughput (HT) duplicate PPDUs, such that AP1 monitoring its anchor channel 410 (e.g., 20MHz, 40MHz or 80MHz anchor channel) may receive at least one copy. The short frame 460 may include a Duration field set= 0 to indicate the channel is idle after the frame. In certain examples, AP2 may determine to transmit the short frame when APTs anchor channel is idle for a time greater than a predefined or announced threshold.

[0097] In some example embodiments, a Short Secondary Access Beacon / Announcement frame may be transmitted by an AP on the anchor channel right after the AP switches to the secondary / anchor channel. In certain embodiments, the Short Secondary Access Beacon / Announcement frame may carry indication of any one or combination of the following items (1 )-(4):(1) A time duration the AP may stay on the anchor channel;(2) An allowed uplink channel access scheme field, indicating if one or more uplink access schemes are allowed The uplink access schemes may include UL trigger-based access, CSMA / CA based uplink access, uplink orthogonal frequency division multiplexing random access (DORA), etc., and may be signalled by predetermined flags or a bitmap, parameter-value pairs, or any other such method;(3) A maximum operating channel width on the secondary channel; and / or(4) Identifications of any punctured subchannels or disabled subchannels on the secondary channel.

[0098] In some embodiments, the AP may determine a dwell time or time to stay on or continue using the anchor channel, based on its NAV setting on the primary channel. For example, the AP which switched to the anchor channel and became the TXOP holder of the anchor channel may determine the time duration to stay on the anchor channel. In one implementation, the AP may determine the time duration to stay on the anchor channel based on the NAV setting on its primary channel.

[0099] In some instances, the AP may need to switch back to the primary channel before the end of the NAV set on the primary channel. In such instances, the AP may not lose medium synchronization on the primary channel since it has the correct NAV setting. In some such implementations, non-AP STAs which participated in a TXOP (e.g. participated in transmissions or receptions) on the anchor channel may need to switch back to the primary channel at the end of the TXOP of the anchor channel, regardless of their own NAV setting on the primary channel

[0100] In other examples, non-AP STAs which participated in TXOP (e.g. participated in transmissions or receptions) on the anchor channel may prefer to stay on the anchor channel longer. This may be due to a longer NAV setting on the primary channel for the STA, or the STA may not want to switch back and forth between the primary channel and anchor channel due to the extra switching delay overhead required (for example, where latency is crucial or if only a small amount of data needs to be transferred). The non-AP STA may inform the AP of its NAV setting on the primary channel if its NAV may be longer than the TXOP or theexpected stay time on the anchor channel, or may simply inform the AP of the decision that the STA will stay on the anchor channel.

[0101] Turning to FIG. 5, a signal diagram 500 illustrating a method of WLAN devices switching between primary and anchor channels is shown according to some example embodiments. In example method diagram 500, an AP and an associated STA may switch from the APs primary channel to the anchor channel. The AP may gain the medium of the anchor channel and start a TXOP 505. Based on the AP’s NAV setting on the primary channel, the AP may set the Duration field of TXOP 505 on the anchor channel For example, it may set the Duration of the TXOP 505 over the anchor channel to the end of the NAV on the primary channel as shown in FIG. 5 However, in the example illustrated, the STA may prefer, e.g , for any of the reasons noted above, to remain on the anchor channel longer than the Duration of TXOP 505 In this case, the STA may transmit a PPDU 510 to the AP over the anchor channel, with the PPDU 505 indicating one or a combination of the following options (1)-(3).(1) The STA may remain on the anchor channel after the end of the TXOP 505. As one example, this may be a one bit or several bit field / subfield which may be carried in a PHY / MAC header with control / management / data transmissions, or a newly defined control / management frame.(2) The STA may remain on the anchor channel until the next Beacon frame transmission from the AP. As an example, if this field / subfield is set, the STA may switch back to the primary channel just before the next Beacon frame. Similarly, as option (1), this may be a one bit or several bit field / subfield which may be carried in a PHY / MAC header with control / management / data transmissions, or a newly defined control / management frame.(3) The STA may signal a specific time duration that the STA may be on the anchor channel (or a duration the STA will remain on the anchor channel after TXOP 505. As an example, a field / subfield referred to as Anchor Channel Duration may be indicated to the AP. An example of the Anchor Channel Duration field / subfield may indicate units of microseconds, time units or a predetermined microsecond length, or any other unit indicative of a time duration.

[0102] Upon reception of the frame / PPDU 510 from the STA indicating the STA will remain on the anchor channel longer than the TXOP 505, the AP may send an acknowledgement (ACK) to the STA over the anchor channel (not shown) At the end of the anchor channel TXOP 505, the AP may switch back to monitor the primary channel The AP may obtain priority over the medium on the primary channel and it may have a clear channel assessment (CCA) idle for any or all of the secondary channels including the anchor channel. For example, the AP may start a TXOP 515 on the determined idled channels. The AP may know one or more STAs may be still monitoring the anchor channel, and thus it may transmit a PPDU using orthogonal frequency division multiple access (OFDMA) mode or aggregated PPDU (A-PPDU) mode. In certain implementations, the AP may allocate downlink (DL) resources for the STAs parking on the anchor channel by including the resource allocation field in the SIG field transmitted over the secondary channels including the anchor channel. In such implementations, the SIG field transmitted over the primary channels and secondary channels may not be thesame so the SIG fields for anchor channels may carry more information. In some implementations, the AP may allocate uplink (UL) resources for the STAs parking on the anchor channel by including Trigger frame(s) transmitted over the secondary channels, including the anchor channel.

[0103] Referring to FIG. 6 another method 600 of switching between primary and anchor channels is shown according to an example embodiment. Example method 600 of FIG. 6 allows the AP to switch back to the primary channel while the non-AP STA may stay on the anchor channel. The procedure and settings of FIG. 6, method 600 are similar to those shown in FIG. 5, but in this example embodiment, the AP may suggest / indicate that the non-AP STA stay on the anchor channel after the end of the TXOP on the anchor channel. In this way, the AP may have control over the numberof STAs which park on the primary channel and the number of STAs which park on the secondary channel (including the anchor channel).

[0104] In method 600, after the AP starts a TXOP 605 over the anchor channel / secondary channel, the AP may suggest one or more STAs to stay on the anchor channel longer than the TXOP 605 duration by transmitting an Anchor Channel Operation Request frame 610. The AP may transmit a PPDU to the STA(s) over the anchor channel and in the PPDU, the AP may indicate one or a combination of the following options(1)-(3):(1 ) Whether the STA may be suggested to stay on the anchor channel after the end of the TXOP 605. This may be a one bit or several bit field / subfield which may be carried in PHY / MAC header with control / management / data transmissions, or a newly defined control / management frame;(2) Whether the STA may be suggested to stay on the anchor channel until the next Beacon frame transmission from the AP. If this field / subfield is set, the STA is suggested to switch back to the primary channel just before the next Beacon frame. This may be a one bit or several bit field / subfield which may be carried in PHY / MAC header with control / management / data transmissions, or a newly defined control / management frame; and / or(3) The time duration the STA may be suggested to stay in the anchor channel. The field / subfield may be referred as Anchor Channel Duration (which is shown in FIG. 6 indicating length of time 617). The field / subfield may be in unit of microseconds, time units, or any other such units.

[0105] On reception of the Anchor Channel Operation Request frame 610, each STA may send a response frame 615 to the AP over the anchor channel. The STA may indicate via the response frame 615 if it accepts the ARs suggestion or potentially indicates a different time it will remain on the anchor channel.

[0106] At the end of the TXOP 605, the AP may switch back to monitor the primary channel. The AP may obtain priority over the medium on the primary channel and it may determine CCA idle for the secondary channels including the anchor channel. The AP may then start a TXOP 620 on the idled channels. The AP may know one or more STAs may be still monitoring the anchor channel, and thus it may transmit a PPDU using OFDMA mode or A-PPDU mode via the anchor channel It may allocate DL resources for the STAs parking on the anchor channel by including the resource allocation field in the SIG field transmitted over the secondary channels including the anchor channel. In this scenario, the SIG field transmitted over the primary channels- 72 -and secondary channels may not be the same so the SIG fields may carry more information The AP may allocate UL resources for the STAs parking on the anchor channel by including Trigger frame(s) transmitted over the secondary channels, including the anchor channel.

[0107] In various example embodiments, in order to end anchor channel operations, a device, including an AP STA or a non-AP STA, may transmit an End of Anchor Operation frame (not shown) to indicate it may switch back to the primary channel immediately after the frame. This frame may be transmitted over the anchor channel.

[0108] In one implementation, the STA may transmit another End of Anchor Operation frame on the primary channel to announce that it is available on the primary channel. In some implementations, the STA may transmit a short control or action frame on the primary channel to announce that it is available on the primary channel.

[0109] In one example, a method for use in a wireless local area network (WLAN) station (STA), e.g., an AP STA or a non-AP STA, may include determining, based on a primary channel associated with a first AP being unavailable, that the first AP will switch from the primary channel to an anchor channel associated with the first AP. The STA receives, from a second AP, before a timer associated with the first AP expires, a frame indicating that the anchor channel associated with the first AP is idle. In response to receiving the frame from the second AP, the STA accesses the anchor channel associated with the first AP based on a carrier-sense multiple access collision avoidance (CSMA / CA) procedure. Next, the STA transmits, to a second STA, an initial anchor channel control frame to check the second STAs availability in the anchor channel. The STA may then receive a control response frame indicating the second STA is available to transmit and / or receive in the anchor channel.

[0110] In various embodiments, the STA may be the first access point (AP), i.e., an AP STA, or a non-AP STA associated with the first AP. According to one embodiment, the first AP and the second AP are associated with a multi-AP group (MAP). In certain embodiments, the anchor channel associated with the first AP is within a primary channel bandwidth associated with the second AP, e.g., the anchor channel of the first AP is the same as, or a portion of, the primary channel of the second AP. According to various embodiments, the initial anchor channel control frame may be a short control frame including one of a request to send (RTS), a clear to send (GTS), a buffer status report poll (BSRP) frame, a buffer status report response (BSRR) frame or a trigger frame, having a duration field for setting a network allocation vectors (NAVs), set to zero. This enables a STA receiving the control frame on the anchor channel to respond immediately for non-primary channel access on the anchor channel. In one example, the timer associated with the first AP is a synchronization delay timer. In one example, the first AP and the second AP use the same bandwidth.

[0111] According to other embodiments, an example STA / method for use in the STA may include receiving, from an AP that the STA is associated with, an indication of anchor channel(s) for non-primary channel access when a primary channel with the AP is unavailable. The STA determines the primary channel with the AP is unavailable and monitors the indicated anchor channel(s).

[0112] The STA receives, from the AP on one of the monitored anchor channels, a control frame indicating that the respective anchor channel is idle and a duration that the AP will remain on the anchor channel. In response to receiving the control frame, the STA sends, via the anchor channel, a transmission for anchor channel access. According to some embodiments, the STA receives, from the AP on the anchor channel, a transmission opportunity (TXOP) for the STA to transmit on the anchor channel. In one example, the STA then sends, to the AP on the anchor channel during the TXOP, an indication, e g., using an Anchor Channel Duration frame, that the STA will remain on the anchor channel following the TXOP, for longer than the duration that the AP indicated it will remain on the anchor channel. In a variation example, prior to sending the indication that the STA will remain on the anchor channel following the TXOP, the STA receives, from the AP on the anchor channel, an indication, e.g., an Anchor Channel Operation Request frame, that the STA should remain of the anchor channel following the TXOP.

[0113] In various implementations, the control frame may be one of a request to send (RTS), a clear to send (CTS), a buffer status report poll (BSRP) frame or a trigger frame. In certain aspects, the control frame may have a duration field, which is used by STAs in setting their network allocation vectors (NAVs), set to zero to enable the STA to immediately contend for anchor channel access. In various examples, the anchor channel is a secondary channel of bandwidth of the AP used for channel bonding. In various examples, the anchor channel conforms to a primary channel of a second AP in a multi-AP group (MAP) with the AP. In other aspects, the present disclosure is directed to any of a wireless transmit receive unit (WTRU); an access point (AP); a station (STA); at least one processor operatively connected to at least one transceiver; a network device; a computing device; and / or an integrated circuit configured to, or a non-transitory computer readable medium comprising instructions which when executed by a processing device cause the processing device to, perform any of the above discussed method implementations.

[0114] Although features and elements are described above in particular combinations, one of ordinary skill in the art will appreciate that each feature or element can be used alone or in any combination with the other features and elements. In addition, the methods described herein may be implemented in a computer program, software, or firmware incorporated in a computer-readable medium for execution by a computer or processor. Examples of computer-readable media include electronic signals (transmitted over wired or wireless connections) and computer-readable storage media. Examples of computer-readable storage media include, but are not limited to, a read only memory (ROM), a random access memory (RAM), a register, cache memory, semiconductor memory devices, magnetic media such as internal hard disks and removable disks, magnetooptical media, and optical media such as CD-ROM disks, and digital versatile disks (DVDs). A processor in association with software may be used to implement a radio frequency transceiver for use in a WTRU, UE, terminal, base station, RNC, or any host computer.

Claims

CLAIMSWhat is Claimed:1 . A method for use in a station (STA), the method comprising: determining, based on a primary channel associated with a first access point (AP) being unavailable, that the first AP will switch from the primary channel to an anchor channel associated with the first AP; receiving, from a second AP, before a timer associated with the first AP expires, a frame indicating that the anchor channel associated with the first AP is idle; accessing the anchor channel associated with the first AP based on a carrier-sense multiple access collision avoidance (CSMA / CA) procedure; transmitting, to a second STA, an initial anchor channel control frame to check the second STAs availability in the anchor channel; and receiving a control response frame indicating the second STA is available to transmit and receive in the anchor channel.

2. The method of claim 1 , wherein the STA is the first AP or a non-AP STA associated with the first AP.

3. The method of claim 1 , wherein the first AP and the second AP are associated in a multi-AP (MAP) group.

4. The method of claim 1, wherein the anchor channel associated with the first AP is within a primary channel bandwidth of the second AP.

5. The method of claim 1 , wherein the initial anchor channel control frame is one of a request to send (RTS) frame, a clear to send (CTS) frame, a buffer status report poll (BSRP) frame, a buffer status report response (BSRR) frame, or a trigger frame, and wherein the control frame has a duration field set to zero for setting a network allocation vector (NAV) of a recipient.

6. The method of claim 1 , wherein the timer associated with the first AP comprises a synchronization delay timer.

7. The method of claim 1 , wherein the first AP and the second AP use a same bandwidth8. A station (STA) comprising: a transceiver; and a processor communicatively coupled to the transceiver; wherein the transceiver and the processor are configured to: determine, based on a primary channel associated with a first access point (AP) being unavailable, that the first AP will switch from the primary channel to an anchor channel associated with the first AP;receive, from a second AP, before a timer associated with the first AP expires, a frame indicating that the anchor channel associated with the first AP is idle; access the anchor channel associated with the first AP based on a carrier-sense multiple access collision avoidance (CSMA / CA) procedure; transmit, to a second STA, an initial anchor channel control frame to check the second STAs availability in the anchor channel; and receive a control response frame indicating the second STA is available to transmit and receive in the anchor channel.

9. The STA of claim 8, wherein the STA is the first AP or a non-AP STA associated with the first AP.

10. The STA of claim 8, wherein the first AP and the second AP are in a multi-AP (MAP) group.

11. The STA of claim 8, wherein the anchor channel associated with the first AP is within a primary channel bandwidth of the second AP.

12. The STA of claim 8, wherein the initial anchor channel control frame is one of a request to send (RTS) frame, a clear to send (GTS) frame, a buffer status report poll (BSRP) frame, a buffer status report response (BSRR) frame, or a trigger frame, wherein the control frame has a duration field set to zero for setting a network allocation vector (NAV) of a recipient.

13. The STA of claim 8, wherein the timer associated with the first AP comprises a synchronization delay timer.

14. The STA of claim 8, wherein the first AP and the second AP use a same bandwidth15. A method for use in a station (STA), the method comprising: receiving, from an access point (AP) the STA is associated with, an indication of an anchor channel for non-primary channel access when a primary channel with the AP is unavailable; determining the primary channel with the AP is unavailable; monitoring the anchor channel; receiving, from the AP on the anchor channel, a control frame indicating that the anchor channel is idle and a duration that the AP will remain on the anchor channel; and in response to receiving the control frame, sending, via the anchor channel, a transmission for anchor channel access.

16. The method of claim 15, further comprising: receiving, from the AP on the anchor channel, a transmission opportunity (TXOP) for the STA to transmit on the anchor channel; andsending, to the AP on the anchor channel during the TXOP, an indication that the STA will remain on the anchor channel following the TXOP, for longer than the indicated duration that the AP will remain on the anchor channel.

17. The method of claim 16, wherein prior to sending the indication that the STA will remain on the anchor channel following the TXOP, the method further comprises: receiving, from the AP on the anchor channel, an indication that the STA should remain of the anchor channel following the TXOP.

18. The method of claim 15, wherein the control frame comprises one of a request to send (RTS) frame, a clear to send (CTS) frame, a buffer status report poll (BSRP) frame or a trigger frame, and wherein the control frame has a duration field set to zero for setting a network allocation vector (NAV) of a recipient.

19. The method of claim 15, wherein the anchor channel is a secondary channel of bandwidth of the AP used for channel bonding20. The method of claim 19, wherein the anchor channel is within a primary channel bandwidth of a second AP in a multi-AP (MAP) group with the AP.-7J -

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