Methods for non-primary channel access in WLAN systems

Abstract

Methods and procedures for non-primary channel access (NPCA) are provided herein. A method performed by a non-access point (AP) station (STA) may include receiving a physical layer protocol data unit (PPDU) in a primary channel and operating in an NPCA primary channel. The non-AP STA may operate in an NPCA primary channel in response to determining that the PPDU is not transmitted by an AP-STA the non-AP STA is associated with or by an AP-STA belonging to a group the non-AP STA is associated with, determining that the non-AP STA is not an intended recipient of the PPDU, determining the NPCA primary channel is idle, and determining that a network allocation vector (NAV) set by the PPDU is greater than a threshold.

Description

METHODS FOR NON-PRIMARY CHANNEL ACCESS IN WLAN SYSTEMSCROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims the benefit of U.S. Provisional Application No. 63 / 620,441 , filed January 12, 2024, the contents of which are incorporated herein by reference.BACKGROUND

[0002] A wireless local area network (WLAN) that uses or is established in accordance with an infrastructure Basic Service Set (BSS) mode may include an Access Point (AP) associated with the BSS and one or more stations (STAs) associated with the AP. Both APs and STAs may be alternatively referred to herein as ST As: for example, the AP may be referred to in various examples herein as an AP-STA, while the aforementioned STAs may also be referred to as non-AP-STAs. TheAP typically has access to, or interfaces with, a Distribution System (DS) or another type of wired / wireless network that carries traffic in and out of the BSS. Traffic destined for STAs in the BSS that originates from outside the BSS may arrive through the AP and be delivered to the STAs. T raffic originating from STAs in the BSS that is being sent to destinations outside the BSS may be sent to the AP for delivery to the respective destinations. Traffic between STAs within the BSS may also be sent through the AP, such that 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 may also considered or referred to as 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 may have an AP, and / or STAs, communicating directly with each other. This mode of communication may be referred to as an “ad-hoc” mode of communication.SUMMARY

[0003] Methods and procedures for non-primary channel access (NPCA) are provided herein. A method performed by a non-access point (AP) station (STA) may include receiving a physical layer protocol data unit (PPDU) in a primary channel, and operating in an NPCA primary channel. The non-AP STA may operate in the NPCA primary channel in response to determining that the PPDU is not transmitted by an AP-STA the non-AP STA is associated with or by an AP-STA belonging to a group the non-AP STA is associated with, determining that the non-AP STA is not an intended recipient of the PPDU, determining the NPCA primary channel is idle, and determining that a network allocation vector (NAV) set by the PPDU is greater than a NPCA Minimum Duration threshold.BRIEF DESCRIPTION OF THE DRAWINGS

[0004] 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:

[0005] FIG. 1A is a system diagram illustrating an example communications system in which one or more disclosed embodiments may be implemented;

[0006] 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;

[0007] 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;

[0008] 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;

[0009] FIG. 2 is a signaling diagram illustrating an example of individual target wake time (TWT) operation as may be carried out by STAs in a WLAN;

[0010] FIG. 3 is a flow diagram illustrating an exemplary procedure performed by an AP-STA for network allocation vector (NAV) triggered primary / NPCA primary channel switching; and

[0011] FIG. 4 is a flow diagram illustrating an exemplary procedure performed by a non-AP STA.DETAILED DESCRIPTION

[0012] 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), singlecarrier 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.

[0013] 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 (CN) 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 networkelements. 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.

[0014] 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.

[0015] 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 an embodiment, 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.

[0016] 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).

[0017] 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).

[0018] 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).

[0019] 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.

[0020] 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).

[0021] 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.

[0022] 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). 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. 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.

[0023] 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.

[0024] 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.

[0025] 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.

[0026] FIG. 1 B is a system diagram illustrating an example WTRU 102. As shown in FIG. 1 B, 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 will be appreciated that the WTRU 102 may include any sub-combination of the foregoing elements while remaining consistent with an embodiment.

[0027] 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.

[0028] 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.

[0029] 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.

[0030] 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.

[0031] 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).

[0032] 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 moredry 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.

[0033] 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

[0034] 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.

[0035] 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)).

[0036] 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 GN 106.

[0037] 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 MIMOtechnology. 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.

[0038] 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.

[0039] 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.

[0040] 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

[0041] 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.

[0042] 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.

[0043] 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. 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.

[0044] 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.

[0045] In representative embodiments, the other network 112 may be a WLAN.

[0046] 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.

[0047] 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.

[0048] 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.

[0049] 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 two streams. 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).

[0050] 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).

[0051] WLAN systems, which may support multiple channels, and channel bandwidths, such as 802 11 n, 802.11ac, 802.11 af, 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 802.11 ah, 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. More specifically, the NAV is a mechanism used in IEEE 802.11 wireless networks (Wi-Fi) to manage and control medium access by preventing collisions. When a STA transmits a frame, the STA may include a duration field in the MAC header, which may specify how long the medium will be occupied. The duration may include the time for acknowledgments and potential retransmissions. Other stations that receive the frame may read the duration field and set their own NAV timers accordingly This tells them how long they should wait before attempting to access the medium During the period indicated by the NAV, stations defer any transmission attempts, treating the medium as busy even if they cannot detect actual radio signals. Thus, the NAV functions like a timer or counter. When the NAV timer expires, the station can attempt to transmit if the physical carrier-sense mechanism also indicates that the medium is idle.

[0052] 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 802.11 ah is 6 MHz to 26 MHz depending on the country code.

[0053] 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.

[0054] 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).

[0055] 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).

[0056] 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.

[0057] 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.

[0058] 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.

[0059] 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.

[0060] 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.

[0061] 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.

[0062] 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.

[0063] 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.

[0064] 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.

[0065] 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.

[0066] In an Institute for Electrical and Electronics Engineers (IEEE) 802.11ac infrastructure mode of operation, a AP may transmit a beacon on a fixed channel, which may be a primary channel. The primary channel may be 20 MHz wide, and may be considered the operating channel of the BSS. The primary channel may also be used by ST As to establish a connection with the AP. 802.11 systems may utilize Carrier Sense Multiple Access with Collision Avoidance (CSMA / CA) as a fundamental channel access mechanism. In this mode of operation, some or all of the STAs, including APs, may sense an occupancy or vacancy of the primary channel. If the channel is detected or determined to be busy, the STA may “back off”. Hence, one STA may transmit at any given time in a given BSS.

[0067] In accordance with 802.11n, High Throughput (HT) STAs may also use a 40 MHz wide channel for communication. This may be achieved by combining a primary 20 MHz channel with an adjacent 20 MHz channel to form a 40 MHz wide contiguous channel.

[0068] In accordance with 802.11ac, 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. A 160 MHz channel may be formed, for example, bycombining 8 contiguous 20 MHz channels, or by combining two non-contiguous 80 MHz channels, which may be referred to as an 80+80 configuration. For the 80+80 configuration, at the transmitter, the data, after channel encoding, may be passed through a segment parser that divides it into two streams. Inverse Fast Fourier Transform (IFFT) and / or time domain processing may be performed on each stream separately. The streams may then be mapped on to the two channels, and the data may be transmitted. At the receiver, this mechanism is reversed, and the combined data may be sent to the MAC

[0069] Sub 1 GHz modes of operation may be supported when operating in accordance with the 802 11 af and / or 802.11ah standards. In accordance with these specifications, the channel operating bandwidths and carriers may be reduced relative to those used in 802.11 n, and 802.11 ac. For example, 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 802.11ah 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 may also include a requirement for a very long battery life.

[0070] WLAN systems that support multiple channels and channel widths, such as 802.11 n, 802.11 ac, 802.11 af, and 802 11 ah, may provide for 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, of all STAs in operating in a BSS, which supports the smallest bandwidth operating mode. 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. All 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.

[0071] 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 927.5 MHz. The total bandwidth available for 802.11 ah is 6 MHz to 26 MHz depending on the country code.

[0072] Solutions for secondary channel access (SCA) are described herein. In solutions described herein, SCA may also be referred to interchangeably as non-primary channel access (NPCA). Subchannel Selective Transmission (SST) may be understood as one such solution enabling SCA.

[0073] In accordance with 802.11 ax, SST mechanisms may allow a STA to transmit and / or receive on a secondary channel. A HE SST non-AP STA and a HE SST AP may set up SST operation, for example, by negotiating a trigger enabled Target Wake Time (TWT) using individual TWT agreements. TWT operation may allow an AP to manage activity in the BSS in order to minimize contention between STAs and to reduce the amount of time that a STA utilizing a power management mode needs to be awake. This may be achieved byconfiguring or allocating STAs to operate at nonoverlapping times and / or frequencies, and carrying out frame exchanges in predefined service periods (SPs). An individual TWT agreement may be implicit or explicit. A TWT or TWT SP that is set up under an implicit TWT agreement may be referred to as an implicit TWT or implicit TWT SP, respectively. A TWT or TWT SP that is set up under a trigger-enabled TWT agreement may be a trigger-enabled TWT or trigger-enabled TWT SP, respectively. The TWT responding STA of a trigger- enabled TWT agreement may be an AP.

[0074] FIG. 2 illustrates one example of individual TWT operation. In the example shown, aspects of the TWT operation may be carried out by a STA 201 , a STA 202, and a STA 203. The STA 201 shown in FIG. 2 may be referred to herein as a TWT responding STA. As shown in FIG. 2, at 221 , STA 202, which may be referred to herein as a TWT requesting STA, sends a TWT request 221 to the STA 201 , which may be referred to as a TWT responding STA. The STA 201 may be an AP-STA, while the STAs 202 and 203 may be non-AP STAs.

[0075] The TWT request 221 as shown in FIG. 2 may be sent to set up a trigger-enabled TWT agreement. The TWT request 221 may include a set of TWT parameters that are requested, suggested, or demanded for use in a TWT agreement.

[0076] STA 201 accepts the TWT agreement with STA 202 and confirms acceptance by sending the TWT response as shown at 211 . Subsequently, STA 201 sends an unsolicited TWT response, as shown at 212, to STA 203 to set up a trigger-enabled TWT agreement with STA 203. Both TWT agreements may be set up as announced TWTs. An announced TWT may allow the AP to send buffered data to STAs, for example, only after receiving a message or an announcement of an active status from each STA (such as PS-Poll, QoS Null frame etc). On the other hand, an unannounced TWT may not require such an indication from STAs. During the trigger-enabled TWT SP, the STA 201 may send a Basic Trigger frame, as shown at 213, to which the STA 202 and STA 203 indicate that they are awake during the TWT SP. For example, STA 202 indicates that it is awake by sending a PS-Poll frame 222, and STA 203 indicates that it is awake by sending a QoS Null frame 231 in response to the Basic Trigger frame 213.

[0077] In the example shown in FIG. 2, the STA 201 acknowledges receipt of the PS-Poll frame 222 and the QoS Null frame 231 by sending a multi-STA BlockAck frame 214. STA 202 and STA 203 then receive downlink data in a subsequent exchange with the STA 201 , during the TWT SP. For example, STA 201 transmits a DL MU PPDU 215, to which STA 202 and STA 203 respond by sending BlockAck frames 223 and 232. STA 202 and STA 203 enter a doze state subsequent to the TWT SP

[0078] Table 1 illustrates an example of a TWT element as may be included in a management frame. As illustrated in table 1 , the TWT element may include an Element ID field, a Length field, a Control Field, and / or a TWT Parameter Info field.Table 1 : Example format of a TWT element

[0079] T able 2 illustrates an example of the Control field of the TWT element.Table 2: Control field in TWT element

[0080] Referring to the example of the Control field as shown in Table 2, a Broadcast subfield in the Negotiation Type subfield may indicate whether the TWT element is for a broadcast TWT or an individual TWT. If the Broadcast field of the Negotiation Type subfield is 0 (the TWT element is for individual TWT), then one Individual TWT parameter may be included in the TWT element.

[0081] Table 3 illustrates one example of the format of an Individual TWT Parameter Info field. The TWT Channel subfield in the Individual TWT Parameter Set field may, for example, indicate the subchannels that the STA may need to monitor.Table 3: Individual TWT Parameter Set field

[0082] SST operation may allow a non-AP STA to operate on a secondary 20MHz subchannel or a secondary 80MHz subchannel in a negotiated TWT SP. The non-AP STA may be available at the TWT start time and may not access the medium in the subchannel using DCF or EDCAF. Instead, the channel access for non-AP STA during the SST operation may be trigger-based. This may mean that the AP-STA grants uplink resources for the non-AP STAs to perform uplink transmission. A non-AP STA may include a Channel Switch Timing element in Association Request frames or Reassociation Request frames that it transmits to an AP- STA to indicate the time required by the non-AP STA to switch between different subchannels.

[0083] A description of the Ultra High Reliability (UHR) Study Group is provided herein. The IEEE 802.11 Ultra High Reliability (UHR) Study Group was formed in September 2022. UHR may be considered a major revision to IEEE 802.11 standards following 802.11 be, which is currently in the Working Group Letter Ballot Stage. The UHR Study Group was formed to explore the possibility to improve reliability, support low latency traffic and further increase peak throughput and improve efficiency of the IEEE 802.11 networks. Secondary channel access is one item discussed in the development of 802.11 bn and by the UHR Study Group.

[0084] Methods and procedures proposed herein may be implemented to solve one or more problems as are described herein, though it should be well understood that the proposed methods and procedures may address other problems not explicitly mentioned.

[0085] Various problems relation to SCA, which may be addressed by the UHR Study Group, are described herein. In existing WLAN systems with multiple channel widths, a portion or even a majority of the bandwidth available to a BSS may be wasted due to medium access by a single STA or an OBSS STA that only operates on a portion of the available bandwidth. Methods and procedures described herein may address how to use the secondary channel when the primary channel is busy.

[0086] Proposed solutions are described herein. At least one solution proposed herein may relate to BSS level signaling and procedures to support SCA. SCA mechanisms may allow an AP-STA or a non-AP STA to transmit or receive frames on one or more secondary subchannels when the primary subchannel is busy or occupied either at transmitter side or receiver side or both sides.

[0087] In the case of multi-link operation (MLO), SCA may be supported per link This means a 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. In some methods, support for SCA may be provided per MLD. This means 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.

[0088] In some solutions, the terms AP-STA and non-AP STA may be used. In some solutions, these terms may be replaced by (or used interchangeably with) the terms AP and STA, respectively. In some solutions, these terms may be replaced by (or used interchangeably with) the terms AP-STA MLD and non-AP STA MLD, respectively. In some solutions, these terms may be replaced by (or used interchangeably with) the terms “AP- STA affiliated with an AP-STA MLD” and “non-AP STA affiliated with a non-AP STA MLD”, respectively.

[0089] Solutions involving NAV-triggered primary / anchor channel switching methods (also referred to equivalently as primary / NPCA primary channel switching) are described herein. In some solutions, an AP-STA and / or non-AP STAs may switch to monitor one or more of their secondary subchannels using physical and virtual carrier sensing when the primary channel is busy for the AP-STA and / or the non-AP STAs. The AP-STA may, for example, define and announce one or more anchor channels that may be used as subchannels, where the AP-STA and / or non-AP STAs 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. The STAs (e.g., AP-STA and / or non-AP STAs) may start transmitting when results from the physical and / or virtual carrier sensing determine the wireless media is idle The STAs (e.g., AP-STAs and / or non-AP STAs) may switch back to continue monitoring the primary channel when the primary channel becomes available again.

[0090] In some methods, an anchor channel (which may be referred to equivalently herein as an “NPCA primary channel”) may use a 20MHz resolution or 40MHz resolution. The anchor channel may differ from the primary channel 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. By contrast, the anchor channel may be a 20MHz channel where the STAs switch to perform CCA / NAV when the primary channel is occupied. The anchor channel may be considered a secondary channel A secondary channel may use a 20MHz, 40MHz, 60MHz, 80MHz, 160MHz resolution.

[0091] Access to a secondary channel may be carried out through an anchor channel Thus, the term anchor channel access or NPCA may be used to refer to SCA In some examples, an AP-STA may be operating on a 320MHz channel and its primary 20MHz subchannel may be within its primary 160MHz subchannel. In some examples, a 20MHz subchannel in the secondary 160MHz subchannel may be selected as an anchor channel. In some examples, more than one anchor channel may be selected. An AP-STA may still be operatingon a 320MHz channel and its primary 20MHz subchannel may be within its primary 80MHz subchannel. A 20MHz subchannel in the secondary 80MHz subchannel, a 20MHz subchannel in the third 80MHz, and a 20MHz subchannel in the fourth 80MHz subchannel may be selected as anchor channels.

[0092] Solutions involving timer-triggered primary / anchor channel switching are described herein. A “timer" as referred to herein may be implemented logically in software through algorithms designed to carry out steps based on a passage of time, or on conditions that an amount of time has elapsed. In some methods, a non-AP STA may switch to the anchor channel after a timer is expired. The non-AP STA may start a timer (e.g. , initiate or begin monitoring a time duration) at the end of a transmission from an associated AP. The non-AP STA may reset the timer if it receives a transmission from the associated AP-STA again. If the timer expires, i.e., the elapsed time is greater than a predefined or pre-negotiated threshold (also referred to herein as a “No AP Transmission Threshold”), then the non-AP STA may consider that its associated AP-STA may switch to the anchor channel and the non-AP STA may need to determine whether it may switch to the anchor channel or roam to another AP-STA. The value of the No AP Transmission Threshold may need to be negotiated with the AP-STA or set by the AP-STA. The value of the No AP Transmission Threshold may be signaled to the non- AP STA by the AP-STA.

[0093] It should be noted that solutions involving timer-triggered primary / anchor channel switching may be used independently with the NAV Triggered primary / anchor switch procedure. This may mean that a non-AP STA may switch from primary to anchor using either the NAV triggered primary / anchor switch procedure or timer triggered primary / anchor switch procedure, or a combination of both procedures. A combination of both procedures may involve a subset of the steps of a NAV triggered primary / anchor switch procedure and / or a subset of the steps of a timer triggered primary / anchor switch procedure as described herein.

[0094] Device capabilities indicating support for SCA (e.g., NPCA) are described herein An AP-STA (or AP MLD) and / or non-AP STAs (or non-AP MLDs) may set a Secondary Channel Access Support subfield in its respective transmitted UHR Capabilities element(s) or other capabilities element(s) to 1 to indicate support for SCA. Otherwise, the AP / AP MLD and non-AP STA / STA MLD may set the Secondary Channel Access Support subfield to 0. The AP may send the UHR Capabilities element or other capabilities element that carries the SCA Support subfield in a Beacon frame, (Re)Association Response frame, a Probe Response frame, or other types of frames that it may transmit. The non-AP STAs may send the UHR Capabilities element or other capabilities element which carries the SCA Support subfield in a (Re)Association Request frame, Probe Request frame or other types of frames that they may transmit. The SCA Support subfield may also be referred to equivalently herein as a “subfield” that indicates support for SCA or NPCA.

[0095] If an AP-STA that announces its support for SCA is affiliated with an AP MLD, each AP-STA affiliated with the AP-STA MLD may announce if other AP-STAs affiliated with the same MLD support SCA by sending the UHR Capabilities element or other capabilities element which carries the SCA Support subfield in any one or more of an ML element, Reconfiguration ML element, Reduce Neighbor Report element, and / or MultipleBSSID element in Beacon frame, (Re)Association Response frame, Probe Response frame, ML Probe Response frame, Multi-Link Operation Update Response frame, or another type of frame.

[0096] If a non-AP STA that announces its support for SCA is affiliated with a non-AP MLD, each non-AP STA affiliated with the STA MLD may announce if other non-AP STAs affiliated with the same MLD support SCA by sending the UHR Capabilities element or other capabilities element which carries the SCA Support subfield in any one or more of an ML element, Reconfiguration ML element in (Re)Association Request frame, Probe Request frame, ML Probe Request frame, Multi-Link Operation Update Request frame, or another type of frame.

[0097] Anchor channel announcements are described herein An AP-STA may announce an anchor channel or a set of anchor channels using an Anchor Channel field / subfield carried in one or more elements, management frames, control frames, or data frames. In some methods, the anchor channel may be a per link parameter when multi-link operation is considered. If the APOSTA is affiliated with an AP MLD, each AP affiliated with the same AP MLD may indicate the anchor channel(s) that other AP-STAs affiliated with the same AP MLD may use by sending the Anchor Channel field / subfield in the Per-STA Profile subelement in the ML element, Reconfiguration ML element, Reduced Neighbor Report element, and / or Multiple BSSID element in Beacon frame, (Re)Association Response frame, Probe Response frame, ML Probe Response frame In this way, non-AP STAs operating on other links may observe that the anchor channel set by the corresponding AP- STA affiliated with the same AP-STA MLD. An anchor channel field / subfield may be referred to equivalently as a subfield that indicates or announces an NPCA primary channel or a set of NPCA primary channels.

[0098] Table 4 illustrates an example of an Anchor Channel subfield format. The Anchor Channel Bitmap field / subfield may be a bitmap with N bits. The number of bits, N, may depend on the maximum supported bandwidth of the 802.11 amendment. If the maximum supported bandwidth is X MHz, then the number of bits defined for the Anchor Channel subfield may be greater than or equal to ceiling(X / 20) bits, i.e., N > ceiling (X / 20). For example, if the maximum supported bandwidth is 320MHz, then the number of bits defined for the Anchor Channel Bitmap subfield may be greater than or equal to 320 / 20 = 16 bits. Each bit in the subfield may represent a 20MHz subchannel in certain order (e.g., in order from the lowest frequency to the highest frequency). It should be noted that if the AP’s operating bandwidth (i.e., Y MHz) is smaller than the maximum supported bandwidth, then the first ceiling (Y / 20) bits may be meaningful. For example, if the bit is set to 1 , it may indicate the corresponding 20MHz subchannel may be used as an anchor channelTable 4: Exemplary Anchor Channel field / subfield format

[0099] The Anchor Channel Order subfield may use or be interpreted using a look-up table. This subfield may indicate which anchor channel may be used first when the primary channel is busy, and / or which anchor channel may be used second after the primary channel and the first anchor channel, and so on. An Anchor Channel Order subfield may be referred to equivalently as a subfield that indicates an NCPA channel that may be used first when the primary channel is busy.

[0100] T able 5 illustrates an example encoding of an Anchor Channel Order subfield. In the example shown, the anchor channels may be numbered from lowest frequency to the highest frequency using numbers starting from 0. For example, if two anchor channels are signaled, index 0 may be used to indicate the anchor channel with lower frequency, and index 1 may be used to indicate the anchor channel with higher frequency. The same methods may be used to indicate a greater number of anchor channels.T able 5: Exemplary encoding of Anchor Channel Order subfield

[0101] NAV duration thresholds are described herein. The non-AP STAs may announce a NAV duration threshold in an NAV Duration Threshold field / subfield, which may be carried in one or more elements, management frames, control frames, or data frames. If a non-AP STA has a NAV set by OBSS STAs or P2P transmissions, and the NAV duration is bigger than the NAV duration threshold value carried in the NAV Duration Threshold field / subfield, the STA (e g., AP / STA), may switch to the secondary channel. In some examples, the term “NAV Duration Threshold” as is used herein may be used interchangeably with the terms “Minimum Duration threshold,” “Minimum Duration,” “Duration threshold” “NPCA Minimum Duration threshold,” “NPCA Minimum Duration,” NPCA Duration threshold,” or simply “NPCA Duration.” In some examples, a NAV Duration threshold may be referred to generically as a duration, a time period, a time window, or a timer.

[0102] A NAV duration threshold (referred to alternatively as a NPCA Minimum Duration Threshold) field may indicate the minimum duration of inter-BSS activity (e g., one or more inter-BSS PPDUs or inter-BSS TXOPs) that is required to have been indicated on the primary channel of the BSS as a necessary condition to permit an NPCA STA to switch to the NPCA primary channel to perform NPCA operation.

[0103] In some methods, the value carried in the NAV Duration Threshold field / subfield may be a per-BSS parameter determined and sent or announced by an AP-STA. The AP-STA may include or announce this field / subfield, for example, in a Beacon frame, (Re)Association Response frame, Probe Response frame, or another type of frame that it may transmit.

[0104] In some methods, the NAV Duration Threshold may be a per-STA parameter determined and announced by non-AP STAs. Each non-AP STA may indicate its NAV duration threshold in the NAV Duration Threshold field / subfield in a management frame, action frame, control frame or data frame that it transmits.

[0105] In some methods, the NAV duration threshold may be a per-link parameter when multi-link operation is considered. If the AP-STA is affiliated with an AP MLD, each AP-STA affiliated with the same AP MLD may indicate the value that the other AP-STAs affiliated with the same AP MLD may use to set the NAV duration threshold. The AP-STA may do this by sending the NAV Duration Threshold field / subfield in the Per-STA Profile subelement in an ML element, Reconfiguration ML element, Reduced Neighbor Report element, Multiple BSSID element, or another type of element / sub-element carried in a Beacon frame, (Re)Association Response frame, Probe Response frame, ML Probe Response frame, or another type of frame that it may transmit. In this way, STAs operating on other links may observe the NAV duration threshold set by the corresponding AP-STA affiliated with the same AP MLD.

[0106] In some methods, the NAV duration threshold may be a per-MLD parameter when multi-link operation is considered. The NAV Duration Threshold field / subfield may be carried in a ML element, Reconfiguration ML element, and / or other types of elements.

[0107] In some methods, a NAV duration threshold parameter may be configurable such that an AP-STA or a non-AP STA may access a channel flexibly by configuring the parameter. In this way, the non-AP STA may be able to support low latency traffic and other type of high priority traffic easily. For example, the NAV duration threshold may be set to a smaller value for low latency traffic or high priority traffic than the normal traffic, such that the STAs with low latency traffic or high priority traffic may switch to the non-primary channel while the STAs with other traffic may not switch. In this way, the STAs with low latency traffic / high priority traffic may have a greater chance of gaining control or the non-primary channel through contention. The NAV Duration Threshold field / subfield may be carried in a frame that may be transmitted more frequently. For example, a frame such as a Control frame or another type of frame, or a MAC header field may carry a NAV Duration Threshold field / subfield.

[0108] In some methods, the NAV Duration Threshold field / subfield may indicate a duration in unit of microsecond or TU. In some methods, there may be limited number of preselected values for the NAV Duration Threshold field / subfield and a non-AP STA may need to indicate one or more values via signaling. For example, the non-AP STA may indicate or include an index associated with a value in the NAV Duration Threshold field / subfield. In some methods, the set of values for the threshold may be configurable by an AP-STA. For example, an AP-STA may announce the set of values in a frame, such as a BSS level management frame which may in some examples be a Beacon frame. An AP-STA and / or non-AP STA may use an index associated with a specific value within the set to indicate a threshold value

[0109] Stay Away Time parameters, include maximum Stay Away Time and minimum Stay Away Time parameters are described herein. STAs, including AP-STAs and non-AP STAs may determine to perform certain actions based on the Stay Away Time, such as performing primary / anchor channel switch, or entering or exiting power saving modes. A Stay Away Time may be provided with respect to a Primary channel STAs, including AP-STAs and non-AP STAs, may announce the maximum and / or minimum stay away time from the primary channel

[0110] In some methods, an AP-STA may announce a Maximum Stay Away Time and / or Minimum Stay Away Time for itself in an element which may be carried in a Beacon frame, (Re)Association Response frame, Probe Response frame, or another type of frame. In some methods, an AP-STA may announce a Maximum Stay Away Time and / or Minimum Stay Away Time for other AP-STAs in the same M ulti-BSS I D set in an element which may be carried in the Multiple BSSID element in a Beacon frame, (Re)Association Response frame, Probe Response frame, or another type of frame. In some methods, an AP-STA may announce a Maximum Stay Away Time and / or Minimum Stay Away Time for other AP-STAs affiliated with the same AP MLD in an element which may be carried in the ML element or Reconfiguration ML element in a Beacon frame, (Re)Association Response frame, Probe Response frame, or another type of frame.

[0111] In some methods, an AP-STA may announce a Maximum Stay Away Time and / or Minimum Stay Away Time for other AP-STAs affiliated with the same AP MLD and / or in the same BSSID set in an element which may be carried in the RNR element in a Beacon frame, (Re)Association Response frame, Probe Response frame etc. A non-AP STA may use the information to estimate the time that its associated AP may switch to an anchor channel. A non-AP STA may perform a primary / anchor channel switch, go to power save mode, or take another action based on the estimated time. For example, a non-AP STA may use the Minimum Stay Away Time to determine the time duration that can be used to switch to a power save or doze mode. A non-AP STA may use the Maximum Stay Away Time to determine the time by which the STA should be in active / awake mode.

[0112] In some methods, a non-AP STA may announce a Maximum Stay Away Time and / or Minimum Stay Away Time for itself in an element which may be carried in a (Re)Association Request frame, Probe Request frame, action frame, or another type of frame.

[0113] In some methods, a non-AP STA may announce a Maximum Stay Away Time and / or Minimum Stay Away Time for other non-AP STAs affiliated with the same STA MLD in an element which may be carried in the ML element or Reconfiguration ML element in a (Re)Association Request frame, Probe Request frame, action frame, or another type of frame. An AP-STA may use the information to estimate the time that an associated non-AP STA may switch to an anchor channel and thus it may perform primary / anchor channel switch, go to power save mode, or take another action. The AP-STA may use this information to estimate if the non-AP STA may be available in the anchor / primary channel. For example, the non-AP STA may use the Minimum Stay Away Time to determine the time at which the non-AP STA may switch to and / or begin operate within the anchor channel. The AP-STA may use the Maximum Stay Away Time to estimate the time by which the non-AP STA has switched back to or begun operating in the primary channel.

[0114] Configurations and / or settings maintained by a non-AP STA that determine whether the non-AP STA is to perform SCA are described herein. In some solutions, a non-AP STA may be configured to determine whether to switch to another channel even when other conditions associated with the switch, such as those as described in paragraphs above, are satisfied. For example, in some solutions, a non-AP STA may be configured with one or more settings such that SCA is enabled or disabled irrespective of whether other conditions forSCA operation are met The non-AP STA may indicate whether SCA is enabled or disabled in such situations. In other words, a non-AP STA may indicate whether it is willing to switch to park on the anchor channel (i.e., whether SCA operation is enabled or disabled), for example, if all of the other channel switch conditions met. This indication may be updated by the non-AP STA from time to time. For example, SCA may be enabled at a first time instance, time 1 , ) while SCA may be disabled at second time instance, time 2. The non-AP STA may provide an indication as to whether SCA is enabled or disabled via a SCA Ready field / su bfield, or via another field / subfield which may be defined in an element, a field, MAC header, PHY header, a control frame, a management frame or a data frame. A non-AP STA may transmit a frame carrying the SCA Ready field / subfield to the AP-STA. An SCA Ready field / subfield may be referred to equivalently as an NPCA Ready field / subfield.

[0115] Configurations and / or settings maintained by an AP-STA that determine whether the AP-STA is to carry out steps for SCA are described herein. In some solutions, an AP-STA may be configured to determine whether to switch to another channel even when other conditions associated with the switch, such as those as described in paragraphs above, are satisfied. In some solutions, an AP-STA may be configured with one or more settings such that SCA is enabled or disabled irrespective of whether other conditions for SCA operation are met. The AP-STA may indicate whether SCA is enabled or disabled in such situations. In other words, an AP-STA may indicate whether it is willing to switch to park on the anchor channel (i.e., whether SCA operation is enabled or disabled), for example, if all of the other channel switch conditions met. The AP-STA may update its indication from time to time. For example, SCA may be enabled at a first time instance, time 1 , a while SCA may be disabled at second time instance, time 2. An AP-STA may provide such an indication as to whether SCA is enabled or disabled via a field / subfield, which may be defined in an element or frame. An AP-STA may transmit a frame carrying the indication to one or more non-AP STAs or to one or more other AP-STAs.

[0116] An AP-STA that receives such indication whether another STA (e.g., an non-AP STA is configured to perform SCA despite other conditions being met may determine whether and / or when to perform transmissions on primary and / or secondary channels. If the AP-STA receives a frame that includes a SCA Ready field / subfield, and the SCA Ready field / subfield is set to 0, the AP-STA may know that the non-AP STA is not going to perform SCA and that the non-AP STA will monitor the primary channel Thus, if the primary channel is busy, the AP-STA may not send transmissions to the non-AP STA on the primary or secondary channels If the SCA Ready field / subfield is set to 0, the AP-STA may determine that the non-AP STA is configured to perform SCA and the AP-STA may transmit to the non-AP STA using a secondary channel, for example, when the primary channel is busy. The non-AP STA may indicate a change to this setting or configuration by transmitting another frame carrying the SCA Ready field / subfield.

[0117] In some methods, the SCA Ready field / subfield may carry a per link parameter when multi-link operation is considered. If a non-AP STA is affiliated with a STA MLD, each non-AP STA affiliated with the same STA MLD may indicate the SCA Ready field / subfield(s) set by other non-AP STAs affiliated with the same STA MLD. An SCA Ready field / subfield may be carried in the Per-STA Profile subelement that is included in, for example, the ML element, Reconfiguration ML element transmitted in a (Re)Association Request frame, Probe Request frame, ML Probe Request frame, or another type of frame.

[0118] Primary / anchor channel switch conditions and procedures are further described herein. Detailed procedures for NAV triggered primary / anchor channel switch are discussed. In some examples described herein, when the NAV is set by an OBSS transmission or intra-BSS P2P transmission on the primary channel and the NAV is greater the NAV duration threshold, the AP / STA may switch to its anchor channel.

[0119] FIG. 3 is a flow diagram illustrating an exemplary procedure performed by an AP-STA for NAV triggered primary / NPCA primary channel switching. An AP-STA that supports NPCA and has NPCA enabled (or, in other words, is configured to or “willing to” perform NPCA) may follow a procedure shown in FIG. 3 to switch to an NPCA primary channel, according to one or more steps described in the following paragraphs.

[0120] As shown in FIG. 3, at 310 for example, an AP-STA may receive a PPDU. At 320, the AP-STA may determine whether the AP-STA is an intended recipient of the PPDU by reading one or more fields. If the AP- STA is not an intended receiver, it may then proceed to check the next condition. Otherwise, the AP-STA continues to operate on the primary channel, as shown at 311 .

[0121] The AP-STA may determine whether the AP-STA is an intended recipient based on content (e.g., one or more fields or subfields), one or more classifications, or one or more characteristics of the PPDU. One or more methods below may be used for an early determination that the AP-STA is not an intended recipient of the PPDU. For example, if the PPDU is classified as an Inter-BSS PPDU, then the AP-STA may not be the intended receiver of the PPDU.

[0122] A DL / UL field included in a PHY header (e.g., one of the SIG fields) of the PPDU may indicate whether the transmission is a DL or an UL transmission If the DL / UL field included in the PPDU indicates the transmission is a DL transmission, or an RXVECTOR parameter UPLINK_FLAG is set to 0, then the AP-STA may determine it is not an intended recipient of the PPDU.

[0123] In some scenarios, Multiple Access Point (MAP) operation may be configured or enabled for use by devices in an 802.11 network. In the case that the MAP operation is allowed, a special rule may be applied to the DL / UL field. In some examples, the DL / UL field in the PHY header may be set to 1 to indicate the PPDU is addressed to an AP-STA (and, correspondingly, the RXVECTOR parameter UPLINK_FLAG may be set to 1), including uplink transmissions and AP-to-AP transmissions. The DL / UL field in the PHY header may be set to 0 to indicate the PPDU is addressed to a non-AP STA (and, correspondingly, the RXVECTOR parameter UPLINK_FLAG may be set to 0), including downlink transmissions and P2P transmissions between a pair of non-AP STAs. In these scenarios, if the DL / UL field in the PHY header (e.g., one of the SIG fields) indicates the transmission is addressed to a non-AP STA or the RXVECTOR parameter UPLINK_FLAG is 0, then the AP-STA may determine it is not the intended receiver of the PPDU.

[0124] In some examples, a new MAP field may be defined and carried in the PHY header. The MAP field may be interpreted along with the DL / UL field according to one or more rules. The MAP field may, for example, indicate whether the transmission is destined within the MAP BSS (M-BSS). The M-BSS may include multiple AP-STAs which form a MAP group and the non-AP STAs associated with the AP-STAs. When the MAP field is set to 0 and the DL / UL field indicates DL, the MAP field and the DL / UL field may be interpreted such that therecipient determines the transmission is addressed to a non-AP STA and transmitted out of the M-BSS. When the MAP field is set to 0 and the DL / UL field indicates UL, a recipient may determine the transmission is addressed to an AP-STA and destined or transmitted out of the M-BSS. When the MAP field is set to 1 and DL / UL field indicates DL, it a recipient may determine the transmission is addressed to a non-AP STA and destined or transmitted within the M-BSS. When the MAP field is set to 0 and the DL / UL field indicates UL, a recipient may determine the transmission is addressed to an AP-STA and transmitted within the M-BSS. For AP-to-AP transmissions within the M-BSS, the MAP field may be set to 1 and the DL / UL field may be set to 0 (indicating the transmission is addressed to an AP). For STA-to-STA transmissions within the M-BSS, the MAP field may be set to 1 and the DL / UL field may be set to 1 (indicating the transmission is addressed to a non-AP STA).

[0125] Table 6 illustrates an example of an interpretation of the MAP field and DL / UL field when MAP operation is enabled.Table 6: Interpretations of MAP field and DL / UL field when MAP operation is considered

[0126] A BSS Color field may be included in the PHY header (one of the SIG fields) of a PPDU. The BSS Color field may assist devices in distinguishing between overlapping networks, enhancing spatial reuse and reducing co-channel interference. The BSS Color field included in the PPDU may be used to determine a BSS associated with the PPDU. If the BSS Color field is not 0 and does not indicate the same BSS Color used by the AP-STA, or the RXVECTOR parameter BSS_COLOR is not 0 or not the BSS color of the BSS, then the AP-STA may determine the PPDU is included in an OBSS transmission and it is not the intended receiver of the PPDU.

[0127] In the case that the MAP operation is allowed, a MAP BSS Color may be defined and carried in the PHY header of the PPDU. The MAP BSS Color field may be set to a value to indicate the transmission is from a MAP BSS. If the value carried in the MAP BSS Color field in the PHY header (e.g. , one of the SIG fields) is not the BSS color the AP-STA used or the AP-STA belongs to, or the RXVECTOR parameter BSS_COLOR or MAP_BSS_COLOR is not the BSS color of the BSS or the MAP BSS, then the AP-STA may determine it is not an intended recipient of the PPDU.

[0128] If a PPDU is a VHT PPDU and a GroupJD field in the PHY header (e.g., a VHT-SIG-A field) is not 0, or the RXVECTOR parameter GROUPJD is not 0, then it may be interpreted as either a VHT SU PPDU sent by an AP-STA or a VHT MU PPDU sent by an AP-STA, and thus the AP-STA may determine it is an OBSS transmission and it is not the intended receiver of the PPDU.

[0129] Further with respect to FIG. 3, at 330, the AP-STA may check the NAV set by the PPDU and compare it with the NAV duration threshold, substantially according to one or more examples described inparagraphs above. For example, the AP-STA may determine whether the NAV set by the PPDU is greater than a threshold (e g., a NAV duration threshold or an NPCA Minimum Duration threshold). If the NAV is not greater than the threshold, the AP-STA may proceed to a following step, if applicable; otherwise, the AP-STA may continue operation in the primary channel as shown at 311.

[0130] As shown at 340, the AP-STA may determine whether one or more NPCA primary channels are idle. In some methods, the AP-STA may both check whether there is NAV has been set on one or more NPCA primary channels and perform a CCA on the NPCA primary channel(s) In some methods, the AP-STA may simply perform a CCA on the NPCA primary channel(s). If the NAV is set on the NPCA primary channel(s), or if the CCA indicates that the anchor channel(s) is / are idle, the AP-STA may switch to an NPCA primary channel; otherwise, the AP-STA may determine that the NPCA primary channel is not idle and continue operation in the primary channel, as shown at 311 .

[0131] It should be noted that the conditions illustrated in FIG. 3 and described above may be evaluated with a different order, which may not change the decision of whether the AP-STA may switch to the NPCA primary channel. In some examples, a method performed by an AP-STA for primary / NPCA primary channel switching may perform a subset of the steps shown in FIG. 3 For example, in some methods, the AP-STA need only determine whether the NAV is set for the NPCA primary channel to determine whether to switch to the anchor channel. In some methods, the AP-STA need only determine whether the NAV is greater than a threshold (e.g., a NAV Duration Threshold or an NPCA Minimum Duration Threshold) to determine whether to switch to the NPCA primary channel. In some methods, the AP-STA need only perform a CCA on the NPCA primary channel to determine whether to switch to the NPCA primary channel.

[0132] FIG. 4 is a flow diagram illustrating an exemplary procedure performed by a non-AP STA. A non-AP STA that supports NPCA and is configured / enabled to (i.e., “willing to”) perform NPCA may follow a procedure substantially as illustrated in FIG. 4.

[0133] As shown in FIG. 4, at 410, a non-AP STA may receive a PPDU As shown at 420, the non-AP STA may determine whether the PPDU is received from an associated AP-STA by checking one or more of below fields. If the PPDU is not received from an AP-STA with which the non-AP STA is associated, the non-AP STA may check one or more conditions before determining whether to switch to an NPCA primary channel. If the PPDU is from an AP-STA with which the non-AP STA is associated, the non-AP STA may continue operating on the primary channel as shown at 411 .

[0134] If the PPDU is classified as an inter-BSS PPDU, then the non-AP STA may determine it is not the intended recipient of the PPDU. The classification of inter-BSS PPDU and intra-BSS PPDU may be performed in accordance with one or more methods described substantially in paragraph above, or in accordance with various techniques known in the art.

[0135] In the case that multi-AP transmission may be allowed, the non-AP STA may determine whether the PPDU is sent from its associated AP-STA or an AP-STA which belongs to the same MAP group as its associated AP-STA. With MAP operation, the STA may determine whether the PPDU is sentfrom its associatedAP-STA or an AP-STA belonging to the same MAP group as its associated AP-STA by evaluating one or more conditions. In some examples, a condition may be whether the DL / U L field in the PHY header (e.g., a SIG field included in the PHY header) indicates the transmission is an UL transmission or a RXVECTOR parameter UPLINK_FLAG is set to 1, then the non-AP STA may determine the PPDU is not from its associated AP-STA or an AP-STA belonging to the same MAP group as its associated AP-STA; in some examples, a condition may be based on a value of a MAP BSS Color, which may be defined and carried in the PHY header of the PPDU. The MAP BSS Color field may be set to a value to indicate the transmission is from a MAP BSS. If the MAP BSS Color field in the PHY header (one of the SIG fields) is not the BSS Color the AP-STA used or the AP-STA belongs to, or the RXVECTOR parameter BSS_COLOR or MAP_BSS_COLOR is not the BSS color of the BSS or the MAP BSS, then the non-AP STA may determine the PPDU is not from its associated AP- STA or an AP-STA belonging to the same MAP group as its associated AP-STA.

[0136] As shown at 430, the non-AP STA may determine whether it is an intended recipient of the PPDU. If the PPDU is not sent by its associated AP-STA or an AP-STA in the same MAP group as the associated AP- STA, the PPDU may still be addressed to the non-AP STA by P2P transmission. The non-AP STA may determine if it is an intended recipient STA by checking the Receiver Address field in the MAC header. If the non-AP STA is not an intended recipient, it may evaluate one or more further conditions as illustrated in FIG. 4. If the non-AP STA determines it is an intended recipient, the non-AP STA may continue to operate on the primary channel as shown at 411 .

[0137] As shown at 440, the non-AP STA may determine whether the NAV set by the PPDU is greater than a threshold (e g., a NAV Duration Threshold or an NPCA Minimum Duration threshold). If yes, the non-AP STA may evaluate one or more further conditions as illustrated in FIG. 4. If the NAV set by the PPDU is not greater than the threshold, the non-AP STA may continue operation in the primary channel.

[0138] The non-AP STA may check if the NPCA primary channel is idle. In some methods, the non-AP STA may both determine whether a NAV has been set on one or more NPCA primary channels and perform a CCA on the NPCA primary channel. In some methods, the non-AP STA may only perform a CCA to determine whether the NPCA primary channel is busy. If the NAV has not been set on the anchor channel, or if the non- AP STA determines, based on the CCA, that the NPCA primary channel is not busy, the non-AP STA may switch to an NPCA primary channel; otherwise, the non-AP STA may continue operation in the primary channel.

[0139] It should be noted that the conditions illustrated in FIG. 4 and described above may be evaluated with a different order, which may not change the decision of whether the non-AP STA may switch to the NPCA primary channel In some examples, a method performed by a non-AP STA for primary / NPCA primary channel switching may perform a subset of the steps shown in FIG. 4. For example, in some methods, the non-AP STA need only determine whether the NAV is set for the NPCA primary channel to determine whether to switch to the NPCA primary channel. In some methods, the non-AP STA need only determine whether the NAV is greater than a NAV duration threshold to determine whether to switch to the NPCA primary channel In some methods,the non-AP STA need only perform a CCA on the NPCA primary channel to determine whether to switch to the NPCA primary channel

[0140] It should be noted that some paragraphs above may make reference to an AP-STA or non-AP STA determining whether or how to access a single secondary / NPCA primary channel. It should be appreciated by those of skill in the art that in some methods, there may be multiple secondary / NPCA primary channels that an AP-STA or a non-AP STA may consider switching to. Hence, in some methods, an AP-STA or a non-AP STA may perform one or more actions as described in paragraphs above or illustrated in FIGs. 2-4 with respect to multiple channels. For example, an AP-STA or a non-AP STA may determine whether the NAV is set for one of multiple NPCA primary channels, compare the NAV to a NAV duration threshold, and / or perform a CCA on one or more of multiple NPCA primary channels in order whether to carry out NPCA

[0141] 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 performed by a non-access point (AP) station (STA), the method comprising: receiving a physical layer protocol data unit (PPDU) in a primary channel; and operating in a non-primary channel access (NPCA) primary channel in response to: determining that the PPDU is not transmitted by an AP-STA the non-AP STA is associated with or not transmitted by an AP-STA belonging to group of AP-STAs that the non-AP STA is associated with; determining that the non-AP STA is not an intended recipient of the PPDU, determining the NPCA channel is idle; and determining that a network allocation vector (NAV) set by the PPDU is greater than a NAV duration threshold.

2. The method of claim 1 , wherein the non-AP STA determines it is not an intended recipient of the PPDU based on a determination that: the PPDU is an inter-basic service set (BSS) PPDU; a field included in the PPDU indicates that the PPDU is an uplink (UL) PPDU; or a receiver address (RA) included in the PPDU does not match an address associated with the non- AP STA.

3. The method of claim 1, further comprising ceasing monitoring the primary channel, and wherein operating in the NPCA primary channel further comprises monitoring the NPCA primary channel.

4. The method of claim 1 , wherein operating in the NPCA primary channel further comprises sending or receiving a transmission using the NPCA primary channel.

5. The method of claim 1 , further comprising operating in the NPCA primary channel for a time duration equal to a stay-away time.

6. The method of claim 1 , further comprising operating in the NCPA primary channel after a time duration equal to a stay-away time7. The method of claim 1, wherein determining the NPCA primary channel is idle comprises performing a clear channel assessment (CCA)8. A non-access point (AP) station (STA), the non-AP STA comprising: a processor and a transceiver configured to receive a physical layer protocol data unit (PPDU) in a primary channel; and a processor and a transceiver configured to operate in a non-primary channel access (NPCA) primary channel in response to: determining that the PPDU is not transmitted by an AP-STA the non-AP STA is associated with or not transmitted by an AP-STA belonging to a group of AP-that the non-AP STA is associated with; determining that the non-AP STA is not an intended recipient of the PPDU, determining the NPCA primary channel is idle; and determining that a network allocation vector (NAV) set by the PPDU is greater than a NAV duration threshold.

9. The non-AP STA of claim 8, wherein the non-AP STA determines it is not an intended recipient of the PPDU based on a determination that: the PPDU is an inter-basic service set (BSS) PPDU; a field included in the PPDU indicates that the PPDU is an uplink (UL) PPDU; or a receiver address (RA) included in the PPDU does not match an address associated with the non- AP STA.

10. The non-AP STA of claim 8, the processor and the transceiver further configured to cease monitoring the primary channel and operate in the NPCA primary channel by monitoring the NCPA primary channel.

11. The non-AP STA of claim 8, the processor and the transceiver further configured to operate in the NCPA primary channel by sending or receiving a transmission using the NPCA primary channel.

12. The non-AP STA of claim 8, the processor and the transceiver further configured to operate in the NPCA primary channel for a time duration equal to a stay-away time13. The non-AP STA of claim 8, the processor and the transceiver further configured to operate in the primary channel after the time duration equal to the stay-away time.

14. The non-AP STA of claim 8, the processor and the transceiver further configured to determine the NPCA primary channel is idle by performing a clear channel assessment (CCA).

15. An access point (AP)-station (STA), the AP-STA comprising: a processor and a transceiver configured to receive a physical layer protocol data unit (PPDU) in a primary channel; and a processor and a transceiver configured to operate in a non-primary channel access (NPCA) primary channel in response to: determining that the AP-STA is not an intended recipient of the PPDU; determining the NPCA primary channel is idle; and determining that a network allocation vector (NAV) set by the PPDU is greater than an NPCA NAV duration threshold16. The AP-STA of claim 15, wherein the AP-STA determines it is not an intended recipient of the PPDU based on a determination that: the PPDU is an inter-basic service set (BSS) PPDU; a field included in the PPDU indicates that the PPDU is an uplink (UL) PPDU; or a receiver address (RA) included in the PPDU does not match an address of the AP-STA.

17. The AP-STA of claim 15, the processor and the transceiver further configured to cease monitoring the primary channel and operate in the NPCA primary channel by monitoring the NPCA primary channel.

18. The AP-STA of claim 15, the processor and the transceiver further configured to operate in the NPCA primary channel by sending or receiving a transmission using the NPCA primary channel.

19. The AP-STA of claim 15, the processor and the transceiver further configured to operate in the NPCA primary channel for a time duration equal to a stay-away time20. The AP-STA of claim 15, the processor and the transceiver further configured to determine the NPCA primary channel is idle by performing a clear channel assessment (CCA).

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