Transmission opportunity (TXOP) truncation in non-primary channel access (NPCA) operation

Abstract

A first access point (AP) transmits, via a primary channel (PCH), a first frame that initiates a transmission opportunity (TXOP) on the PCH. Before an end of the TXOP, the first AP transmits, via the PCH, a second frame that truncates the TXOP. Based on transmitting the second frame, the first AP first AP transmits to a second AP, operating on a non-primary channel access (NPCA) PCH during the TXOP, a third frame indicating truncation of the TXOP.

Description

Docket No.: 24-3052PCTTITLETRANSMISSION OPPORTUNITY (TXOP) TRUNCATION IN NON-PRIMARY CHANNEL ACCESS (NPCA) OPERATIONCROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims the benefit of U.S. Provisional Application No. 63 / 716,264, filed November s, 2024, and U.S. Provisional Application No. 63 / 840,192, filed July 8, 2025, all of which are hereby incorporated by reference in their entireties.BRIEF DESCRIPTION OF THE DRAWINGS

[0002] Examples of several of the various embodiments of the present disclosure are described herein with reference to the drawings.

[0003] FIG. 1 illustrates example wireless communication networks in which embodiments of the present disclosure may be implemented.

[0004] FIG. 2 is a block diagram illustrating example implementations of a station (STA) and an access point (AP).

[0005] FIG. 3 illustrates an example of a Medium Access Control (MAC) frame format.

[0006] FIG. 4 illustrates an example trigger frame.

[0007] FIG. 5 illustrates an example multi-user request to send (MU-RTS) trigger frame.

[0008] FIG. 6 illustrates an example common info field.

[0009] FIG. 7 illustrates an example of a Request-to-Send (RTS) / Clear-to-Send (CTS) procedure.

[0010] FIG. 8 is an example that illustrates an MU-RTS / CTS procedure.

[0011] FIG. 9 is an example that illustrates non-primary channel access (NPCA) operation.

[0012] FIG. 10 illustrates virtual and physical carrier sense (CS) functions associated with primary and secondary channels for NPCA operation and non-NPCA operation.

[0013] FIG. 11 shows an example that illustrates NPCA operation.

[0014] FIG. 12 illustrates an example that highlights a problem that may arise in existing NPCA operation.

[0015] FIG. 13 shows an example that illustrates an example NPCA operation according to an embodiment.

[0016] FIG. 14 shows another example that illustrates another example NPCA operation according to an embodiment.

[0017] FIG. 15 shows another example that illustrates another example NPCA operation according to an embodiment

[0018] FIG. 16 shows another example that illustrates another example NPCA operation according to an embodiment.

[0019] FIG. 17 shows another example that illustrates another example NPCA operation according to an embodiment.Docket No.: 24-3052PCT

[0020] FIG. 18 shows another example that illustrates another example NPCA operation according to an embodiment.

[0021] FIG. 19 illustrates an example process according to an embodiment.

[0022] FIG. 20 illustrates another example process according to an embodiment.

[0023] FIG. 21 illustrates another example process according to an embodiment.

[0024] FIG. 22 illustrates another example process according to an embodiment.DETAILED DESCRIPTION

[0025] In the present disclosure, various embodiments are presented as examples of how the disclosed techniques may be implemented and / or how the disclosed techniques may be practiced in environments and scenarios. It will be apparent to persons skilled in the relevant art that various changes in form and detail can be made therein without departing from the scope. After reading the description, it will be apparent to one skilled in the relevant art how to implement alternative embodiments. The present embodiments may not be limited by any of the described exemplary embodiments. The embodiments of the present disclosure will be described with reference to the accompanying drawings. Limitations, features, and / or elements from the disclosed example embodiments may be combined to create further embodiments within the scope of the disclosure. Any figures which highlight the functionality and advantages are presented for example purposes only. The disclosed architecture is sufficiently flexible and configurable, such that it may be utilized in ways other than those shown. For example, the actions listed in any flowchart may be re-ordered or only optionally used in some embodiments.

[0026] Embodiments may be configured to operate as needed. The disclosed mechanism may be performed when certain criteria are met, for example, in a station, an access point, a radio environment, a network, a combination of the above, and / or the like. Example criteria may be based, at least in part, on for example, wireless device or network node configurations, traffic load, initial system set up, packet sizes, traffic characteristics, a combination of the above, and / or the like. When the one or more criteria are met, various example embodiments may be applied. Therefore, it may be possible to implement example embodiments that selectively implement disclosed protocols.

[0027] In this disclosure, “a” and “an” and similar phrases are to be interpreted as “at least one” and “one or more.” Similarly, any term that ends with the suffix “(s)” is to be interpreted as “at least one” and “one or more.” In this disclosure, the term “may” is to be interpreted as “may, for example.” In other words, the term “may” is indicative that the phrase following the term “may” is an example of one of a multitude of suitable possibilities that may, or may not, be employed by one or more of the various embodiments. The terms “comprises” and “consists of’, as used herein, enumerate one or more components of the element being described. The term “comprises” is interchangeable with “includes" and does not exclude unenumerated components from being included in the element being described. By contrast, “consists of provides aDocket No.: 24-3052PCT complete enumeration of the one or more components of the element being described. The term “based on”, as used herein, may be interpreted as “based at least in part on” rather than, for example, “based solely on". The term “and / or” as used herein represents any possible combination of enumerated elements. For example, “A, B, and / or C” may represent A; B; C; A and B; A and C; B and C; or A, B, and C.

[0028] If A and B are sets and every element of A is an element of B, A is called a subset of B. In this specification, only non-empty sets and subsets are considered. For example, possible subsets of B = {STA1 , STA2) are: {STA1}, {STA2}, and {STA1 , STA2}. The phrase “based on” (or equally “based at least on”) is indicative that the phrase following the term “based on” is an example of one of a multitude of suitable possibilities that may, or may not, be employed to one or more of the various embodiments. The phrase “in response to” (or equally “in response at least to”) is indicative that the phrase following the phrase “in response to” is an example of one of a multitude of suitable possibilities that may, or may not, be employed to one or more of the various embodiments. The phrase “depending on” (or equally “depending at least to”) is indicative that the phrase following the phrase “depending on” is an example of one of a multitude of suitable possibilities that may, or may not, be employed to one or more of the various embodiments. The phrase “employing / using” (or equally “employing / using at least”) is indicative that the phrase following the phrase “employing / using” is an example of one of a multitude of suitable possibilities that may, or may not, be employed to one or more of the various embodiments.

[0029] The term configured may relate to the capacity of a device whether the device is in an operational or non-operational state. Configured may refer to specific settings in a device that effect the operational characteristics of the device whether the device is in an operational or non-operational state. In other words, the hardware, software, firmware, registers, memory values, and / or the like may be “configured” within a device, whether the device is in an operational or nonoperational state, to provide the device with specific characteristics. Terms such as “a control message to cause in a device" may mean that a control message has parameters that may be used to configure specific characteristics or may be used to implement certain actions in the device, whether the device is in an operational or non-operational state.

[0030] In this disclosure, parameters (or equally called, fields, or Information elements: IBs) may comprise one or more information objects, and an information object may comprise one or more other objects. For example, if parameter (IE) N comprises parameter (IE) M, and parameter (IE) M comprises parameter (IE) K, and parameter (IE) K comprises parameter (information element) J. Then, for example, N comprises K, and N comprises J. In an example embodiment, when one or more messages / frames comprise a plurality of parameters, it implies that a parameter in the plurality of parameters is in at least one of the one or more messages / frames but does not have to be in each of the one or more messages / frames.

[0031] Many features presented are described as being optional through the use of “may” or the use of parentheses. For the sake of brevity and legibility, the present disclosure does not explicitly recite each and every permutation that may be obtained by choosing from the set of optional features. The present disclosureDocket No.: 24-3052PCT is to be interpreted as explicitly disclosing all such permutations. For example, a system described as having three optional features may be embodied in seven ways, namely with just one of the three possible features, with any two of the three possible features or with three of the three possible features

[0032] Many of the elements described in the disclosed embodiments may be implemented as modules. A module is defined here as an element that performs a defined function and has a defined interface to other elements. The modules described in this disclosure may be implemented in hardware, software in combination with hardware, firmware, wetware (e.g., hardware with a biological element) or a combination thereof, which may be behaviorally equivalent. For example, modules may be implemented as a software routine written in a computer language configured to be executed by a hardware machine (such as C, C++, Fortran, Java, Basic, Matlab or the like) or a modeling / simulation program such as Simulink, Stateflow, GNU Octave, or LabVIEWMathScript. It may be possible to implement modules using physical hardware that incorporates discrete or programmable analog, digital and / or quantum hardware. Examples of programmable hardware comprise: computers, microcontrollers, microprocessors, application-specific integrated circuits (ASICs); field programmable gate arrays (FPGAs); and complex programmable logic devices (CPLDs). Computers, microcontrollers, and microprocessors are programmed using languages such as assembly, C, C++, or the like. FPGAs, ASICs and CPLDs are often programmed using hardware description languages (HDL) such as VHSIC hardware description language (VHDL) or Verilog that configure connections between internal hardware modules with lesser functionality on a programmable device. The mentioned technologies are often used in combination to achieve the result of a functional module.

[0033] FIG. 1 illustrates example wireless communication networks in which embodiments of the present disclosure may be implemented.

[0034] As shown in FIG. 1 , the example wireless communication networks may include an Institute of Electrical and Electronic Engineers (IEEE) 802.11 (WLAN) infra-structure network 102. WLAN infra-structure network 102 may include one or more basic service sets (BSSs) 110 and 120 and a distribution system (DS) 130.

[0035] BSS 110-1 and 110-2 each includes a set of an access point (AP or AP STA) and at least one station (STA or non-AP STA). For example, BSS 110-1 includes an AP 104-1 and a STA 106-1 , and BSS 1 10-2 includes an AP 104-2 and STAs 106-2 and 106-3. The AP and the at least one STA in a BSS perform an association procedure to communicate with each other.

[0036] DS 130 may be configured to connect BSS 110-1 and BSS 110-2. As such, DS 130 may enable an extended service set (ESS) 150. Within ESS 150, APs 104-1 and 104-2 are connected via DS 130 and may have the same service set identification (SSID).

[0037] WLAN infra-structure network 102 may be coupled to one or more external networks. For example, as shown in FIG. 1 , WLAN infra-structure network 102 may be connected to another network 108 (e.g.,Docket No.: 24-3052PCT802.X) via a portal 140. Portal 140 may function as a bridge connecting DS 130 of WLAN infra-structure network 102 with the other network 108.

[0038] The example wireless communication networks illustrated in FIG. 1 may further include one or more ad-hoc networks or independent BSSs (IBSSs). An ad-hoc network or IBSS is a network that includes a plurality of STAs that are within communication range of each other. The plurality of STAs are configured so that they may communicate with each other using direct peer-to-peer communication (i.e., not via an AP).

[0039] For example, in FIG. 1 , STAs 106-4, 106-5, and 106-6 may be configured to form a first IBSS 112- 1 . Similarly, STAs 106-7 and 106-8 may be configured to form a second IBSS 112-2. Since an IBSS does not include an AP, it does not include a centralized management entity. Rather, STAs within an IBSS are managed in a distributed manner. STAs forming an IBSS may be fixed or mobile.

[0040] A STA as a predetermined functional medium may include a medium access control (MAC) layer that complies with an IEEE 802.11 standard. A physical layer interface for a radio medium may be used among the APs and the non-AP stations (STAs). The STA may also be referred to using various other terms, including mobile terminal, wireless device, wireless transmit / receive unit (WTRU), user equipment (UE), mobile station (MS), mobile subscriber unit, or user. For example, the term “user" may be used to denote a STA participating in uplink Multi-user Multiple Input, Multiple Output (MU MIMO) and / or uplink Orthogonal Frequency Division Multiple Access (OFDMA) transmission.

[0041] A physical layer (PHY) protocol data unit (PPDU) may be a composite structure that includes a PHY preamble and a payload in the form of a PHY service data unit (PSDU). For example, the PSDU may include a PHY preamble and header and / or one or more MAC protocol data units (MPDUs). The information provided in the PHY preamble may be used by a receiving device to decode the subsequent data in the PSDU. In instances in which PPDUs are transmitted over a bonded channel (channel formed through channel bonding), the preamble fields may be duplicated and transmitted in each of the multiple component channels. The PHY preamble may include both a legacy portion (or “legacy preamble”) and a non-legacy portion (or “non-legacy preamble”). The legacy preamble may be used for packet detection, automatic gain control and channel estimation, among other uses. The legacy preamble also may generally be used to maintain compatibility with legacy devices. The format of, coding of, and information provided in the non-legacy portion of the preamble is based on the particular IEEE 802.11 protocol to be used to transmit the payload.

[0042] A frequency band may include one or more sub-bands or frequency channels. For example, PPDUs conforming to the IEEE 802.11 n, 802.1 1ac, 802.11 ax and / or 802.11 be standard amendments may be transmitted over the 2.4 GHz, 5 GHz, and / or 6 GHz bands, each of which may be divided into multiple 20 MHz channels. The PPDUs may be transmitted over a physical channel having a minimum bandwidth of 20 MHz. Larger channels may be optionally formed through channel bonding of a primary 20 MHz channel and one or more 20 MHz secondary channels. For example, PPDUs may be transmitted over physical channels having bandwidths of 40 MHz, 80 MHz, 160 MHz, or 320 MHz by bonding together a primary 20 MHz channelDocket No.: 24-3052PCT and 1 , 3, 7, or 15 secondary channel respectively. The primary channel is a common channel operation for all STAs where management frames are sent by the AP to ensure that all STAs (regardless of channel bonding support) can receive.

[0043] FIG. 2 is a block diagram illustrating example implementations of a STA 210 and an AP 260. As shown in FIG. 2, STA 210 may include at least one processor 220, a memory 230, and at least one transceiver 240. AP 260 may include at least one processor 270, a memory 280, and at least one transceiver 290. Processor 220 / 270 may be operatively connected to memory 230 / 280 and / or to transceiver 240 / 290.

[0044] Processor 220 / 270 may implement functions of the PHY layer, the MAC layer, and / or the logical link control (LLC) layer of the corresponding device (STA 210 or AP 260). Processor 220 / 270 may include one or more processors and / or one or more controllers. The one or more processors and / or one or more controllers may comprise, for example, a general-purpose processor, a digital signal processor (DSP), a microcontroller, an application specific integrated circuit (ASIC), a field programmable gate array (FPGA), a logic circuit, or a chipset, for example.

[0045] Memory 230 / 280 may include a read-only memory (ROM), a random-access memory (RAM), a flash memory, a memory card, a storage medium, and / or other storage unit. Memory 230 / 280 may comprise one or more non-transitory computer readable mediums. Memory 230 / 280 may store computer program instructions or code that may be executed by processor 220 / 270 to carry out one or more of the operations / embodiments discussed in the present application. Memory 230 / 280 may be implemented (or positioned) within processor 220 / 270 or external to processor 220 / 270. Memory 230 / 280 may be operatively connected to processor 220 / 270 via various means known in the art.

[0046] Transceiver 240 / 290 may be configured to transmit / receive radio signals. In an embodiment, transceiver 240 / 290 may implement a PHY layer of the corresponding device (STA 210 or AP 260). In an embodiment, STA 210 and / or AP 260 may be a multi-link device (MLD), that is a device capable of operating over multiple links as defined by the IEEE 802.11 standard. As such, STA 210 and / or AP 260 may each implement multiple PHY layers. The multiple PHY layers may be implemented using one or more of transceivers 240 / 290.

[0047] FIG. 3 illustrates an example format of a MAC frame. In operation, a STA may construct a subset of MAC frames for transmission and may decode a subset of received MAC frames upon validation. The particular subsets of frames that a STA may construct and / or decode may be determined by the functions supported by the STA. A STA may validate a received MAC frame using the frame check sequence (FCS) contained in the frame and may interpret certain fields from the MAC headers of all frames.

[0048] As shown in FIG. 3, a MAC frame includes a MAC header, a variable length frame body, and a frame check sequence (FCS).

[0049] The MAC header includes a frame control field, an optional duration / ID field, address fields, an optional sequence control field, an optional QoS control field, and an optional HT control field.Docket No.: 24-3052PCT

[0050] The frame control field includes the following subfields: protocol version, type, subtype, "To DS”, “From DS”, “More Fragments”, retry, power management, “More Data , protected frame, and +HTC.

[0051] The protocol version subfield is invariant in size and placement across all revisions of the IEEE 802.1 1 standard. The value of the protocol version subfield is 0 for MAC frames.

[0052] The type and subtype subfields together identify the function of the MAC frame. There are three frame types: control, data, and management. Each of the frame types has several defined subtypes. Bits within the subtype subfield are used to indicate a specific modification of the basic data frame (subtype 0). For example, in data frames, the most significant bit (MSB) of the subtype subfield, bit 7 (B7) of the frame control field, is defined as the QoS subfield. When the QoS subfield is set to 1 , it indicates a QoS data frame, which is a data frame that contains a QoS control field in its MAC header. The second MSB of the subtype field, bit 6 (B6) of the frame control field, when set to 1 in data subtypes, indicates a data frame that contain no frame body field.

[0053] The “To DS” subfield indicates whether a data frame is destined to the distribution system (DS). The “From DS" subfield indicates whether a data frame originates from the DS.

[0054] The “More Fragments” subfield is set to 1 in all data or management frames that have another fragment to follow the MAC service data unit (MSDU) or MAC management protocol data unit (MMPDU) carried by the MAC frame. The “More Fragments” subfield is set to 0 in all other frames in which the “More Fragments” subfield is present.

[0055] The retry subfield is set to 1 in any data or management frame that is a retransmission of an earlier frame. It is set to 0 in all other frames in which the retry subfield is present. A receiving STA uses this indication to aid it in the process of eliminating duplicate frames. These rules do not apply for frames sent by a STA under a block agreement.

[0056] The power management subfield is used to indicate the power management mode of a STA.

[0057] The “More Data” subfield indicates to a STA in power save (PS) mode that bufferable units (BUs) are buffered for that STA at the AP. The “More Data” subfield is valid in individually addressed data or management frames transmitted by an AP to a STA in PS mode. The “More Data” subfield is set to 1 to indicate that at least one additional buffered BU is present for the STA.

[0058] The protected frame subfield is set to 1 if the frame body field contains information that has been processed by a cryptographic encapsulation algorithm.

[0059] The +HTC subfield indicates that the MAC frame contains an HT control field.

[0060] The duration / ID field of the MAC header indicates various contents depending on the frame type and subtype and the QoS capabilities of the sending STA. For example, in control frames of the power save poll (PS-Poll) subtype, the duration / ID field carries an association identifier (AID) of the STA that transmitted the frame in the 14 least significant bits (LSB), with the 2 most significant bits (MSB) set to 1 . In other framesDocket No.: 24-3052PCT sent by STAs, the duration / ID field contains a duration value (in microseconds) which is used by a recipient to update a network allocation vector (NAV). The NAV is a counter that indicates to a STA an amount of time during which the STA must defer from accessing the shared medium.

[0061] Up to four address fields may be present in the MAC frame format. The address fields are used to indicate the basic service set identifier (BSSID), source address (SA), destination address (DA), transmitting address (TA), and receiving address (RA). Certain frames may not contain some of the address fields. Certain address field usage may be specified by the relative position of the address field (1-4) within the MAC header, independent of the type of address present in that field. Specifically, the address 1 field always identifies the intended receiver(s) of the frame, and the address 2 field, where present, always identifies the transmitter of the frame.

[0062] The sequence control field includes two subfields, a sequence number subfield and a fragment number subfield. The sequence number subfield in data frames indicates the sequence number of the MSDU (if not in an Aggregated MSDU (A-MSDU)) or A-MSDU. The sequence number subfield in management frames indicates the sequence number of the frame. The fragment number subfield indicates the number of each fragment of an MSDU or MMPDU. The fragment number is set to 0 in the first or only fragment of an MSDU or MMPDU and is incremented by one for each successive fragment of that MSDU or MMPDU. The fragment number is set to 0 in a MAC protocol data unit (MPDU) containing an A-MSDU, or in an MPDU containing an MSDU or MMPDU that is not fragmented. The fragment number remains constant in all retransmissions of the fragment.

[0063] The QoS control field identifies the traffic category (TC) or traffic stream (TS) to which the MAC frame belongs. The QoS control field may also indicate various other QoS related, A-MSDU related, and mesh- related information about the frame. This information can vary by frame type, frame subtype, and type of transmitting STA. The QoS control field is present in all data frames in which the QoS subfield of the subtype subfield is equal to 1.

[0064] The HT control field is present in QoS data, QoS null, and management frames as determined by the +HTC subfield of the frame control field.

[0065] The frame body field is a variable length field that contains information specific to individual frame types and subtypes. The frame body may include one or more MSDUs or MMPDUs. The minimum length of the frame body is 0 octets.

[0066] The FCS field contains a 32-bit Cyclic Redundancy Check (CRC) code. The FCS field value is calculated over all of the fields of the MAC header and the frame body field.

[0067] FIG. 4 illustrates an example trigger frame 400. Trigger frame 400 may correspond to a basic trigger frame as defined in the existing IEEE 802.1 1 ax standard amendment. Trigger frame 400 may be used by an AP to allocate resources for and solicit one or more TB PPDU transmissions from one or more STAs. Trigger frame 400 may also carry other information required by a responding STA to transmit a TB PPDU to the AP.Docket No.: 24-3052PCT

[0068] As shown in FIG. 4, trigger frame 400 includes a Frame Control field, a Duration field, a receiver address (RA) field, a transmitter address (TA) field, a Common Info field, a User List Info field, a Padding field, and an FCS field.

[0069] The Frame Control field includes the following subfields: protocol version, type, subtype, To DS, From DS, more fragments, retry, power management, more data, protected frame, and +HTC.

[0070] The Duration field indicates various contents depending on frame type and subtype and the QoS capabilities of the sending STA. For example, in control frames of the power save poll (PS-Poll) subtype, the Duration field carries an association identifier (AID) of the STA that transmitted the frame in the 14 least significant bits (LSB), and the 2 most significant bits (MSB) are both set to 1 . In other frames sent by STAs, the Duration field contains a duration value (in microseconds) which is used by a recipient to update a network allocation vector (NAV).

[0071] The RA field is the address of the STA that is intended to receive the incoming transmission from the transmitting station. The TA field is the address of the STA transmitting trigger frame 400 if trigger frame 400 is addressed to STAs that belong to a single BSS. The TA field is the transmitted BSSID if the trigger frame 400 is addressed to STAs from at least two different BSSs of the multiple BSSID set.

[0072] The common info field may have a format as illustrated by common info field 600 described further below. The common info field specifies a trigger frame type of trigger frame 400, a transmit power of trigger frame 400 in dBm, and several key parameters of a TB PPDU that is transmitted by a STA in response to trigger frame 400. The trigger frame type of a trigger frame used by an AP to receive QoS data using UL MU operation is referred to as a basic trigger frame.

[0073] The User List Info field contains a User Info field per STA addressed in trigger frame 400. The per STA User Info field includes, among others, an AID subfield, an RU Allocation subfield, a Spatial Stream (SS) Allocation subfield, an MCS subfield to be used by a STA in a TB PPDU transmitted in response to trigger frame 400, and a Trigger Dependent User Info subfield. The Trigger Dependent User Info subfield can be used by an AP to specify a preferred access category (AC) per STA. The preferred AC sets the minimum priority AC traffic that can be sent by a participating STA. The AP determines the list of participating STAs, along with the BW, MCS, RU allocation, SS allocation, Tx power, preferred AC, and maximum duration of the TB PPDU per participating STA.

[0074] The Padding field is optionally present in trigger frame 400 to extend the frame length to give recipient STAs enough time to prepare a response for transmission one SIFS (short interframe spacing) after the frame is received. The Padding field, if present, is at least two octets in length and is set to all 1 s.

[0075] The FCS field is used by a STA to validate a received frame and to interpret certain fields from the MAC headers of a frame.

[0076] FIG. 5 illustrates an example multi-user request to send (MU-RTS) trigger frame 500. MU-RTS trigger frame 500 may be used by an AP to solicit simultaneous CTS frames from multiple STAs to transmit aDocket No.: 24-3052PCT downlink (DL) MU PPDU to the multiple STAs. As shown in FIG. 5, MU-RTS trigger frame 500 may comprise a frame control field, a duration field, an RA field, a TA field, a common info field, one or more user info fields, a padding field, and an FCS field. The frame control, TA, RA, padding, and FCS fields may be similar to the corresponding fields of trigger frame 400 described above. The common info field may have a format as illustrated by common info field 600 described further below. The duration field may be set to the time, in microseconds, required to transmit the DL MU PPDU, plus the time required to transmit one CTS frame, one ACK frame (if required), and three SIFS periods.

[0077] The one or more user info fields correspond respectively to the one or more STAs solicited by MU- RTS trigger frame 500. As shown in FIG. 5, a user info field may comprise an AID12 subfield, an RU allocation subfield, reserved bits, and a PS 160 subfield. The AID12 subfield comprises an association identifier of the STA to which the user info field is addressed. The RU allocation subfield indicates a channel on which the solicited STA is to transmit the CTS frame. In an example, this may include a primary 20 MHz channel, a primary 40 MHz, a primary 80 MHz channel, a primary 160 MHz, an 80+80 Mhz channel, or a 320 MHz channel.

[0078] FIG. 6 illustrates an example Common Info field 600. Common Info field 600 may be an embodiment of the Common Info field of trigger frame 400 or MU-RTS trigger frame 500, for example. As shown in FIG. 6, Common Info field 600 may include a Trigger Type subfield, a UL Length subfield, a More TF subfield, a CS required subfield, a UL BW subfield, a Gl and HE / EHT-LTF Type / Triggered TXS Mode subfield, a first Reserved subfield, a Number of HE / EHT-LTF Symbols subfield, a second Reserved subfield, an LDPC Extra Symbol Segment subfield, an AP Tx Power subfield, a Pre-FEC Padding Factor subfield, a PE Disambiguity subfield, an UL Spatial Reuse subfield, a third Reserved subfield, an HE / EHT P160 subfield, a Special User Info Field Flag subfield, an EHT Reserved subfield, a fourth Reserved subfield, and a Trigger Dependent Common Info subfield. The Trigger Type subfield, UL Length subfield, More TF subfield, CS required subfield, UL BW subfield, Gl and HE-LTF Type / Triggered TXS Mode subfield, first Reserved subfield, Number of HE / EHT-LTF Symbols subfield, second Reserved subfield, LDPC Extra Symbol Segment subfield, AP Tx Power subfield, Pre-FEC Padding Factor subfield, PE Disambiguity subfield, UL Spatial Reuse subfield, third Reserved subfield, HE / EHT P160 subfield, Special User Info Field Flag subfield, EHT Reserved subfield, fourth Reserved subfield, and Trigger Dependent Common Info subfield may have the same content and interpretation as corresponding subfields of an EHT variant Common Info field defined in the IEEE 802.11 be draft amendment ("IEEE P802.11 be / D3.1 , March 2023”).

[0079] FIG. 7 illustrates an example 700 of a Request-to-Send (RTS) / Clear-to-Send (CTS) procedure. Example 700 may be an example according to the RTS / CTS procedure as defined in section 10.3.2.9 of the IEEE 802.1 1 standard draft "IEEE P802.1 1-REVme™ / D3.0, April 2023.” As shown in FIG. 7, example 700 may include STAs 702 and 704. Other STAs of the same BSS may also be within communication range of STAs 702 and 704.Docket No.: 24-3052PCT

[0080] In an example, STA 702 may transmit an RTS frame 706 to STA 704. STA 702 may transmit RTS frame 706 to protect from hidden STA(s) the transmission of a data frame 710 that STA 702 intends to transmit. RTS frame 706 may include a Duration / ID field. The Duration / ID field may be set to the time, in microseconds, required to transmit data frame 710, plus one CTS frame, plus one ACK frame (if required), plus three SIRS (Short Interframe Spacing) periods.

[0081] In an example, STA 704 may respond to RTS frame 706 by transmitting a CTS frame 708 to STA 702. CTS frame 708 may be transmitted one SIFS period after RTS frame 706. STA 704 may respond to RTS frame 706 when RTS frame 706 is addressed to STA 704 and after considering the NAV, unless the NAV was set by a frame originating from STA 702. STA 704 may respond to the RTS frame 706 when RTS frame 706 is addressed to STA 704 and if the NAV indicates idle. For a non-S1 G STA, the NAV indicates idle when the NAV count is 0 or when the NAV count is non-zero but a nonbandwidth signaling TA obtained from a TA field of RTS frame 706 matches a saved TXOP holder address. For an S1 G STA, the NAV indicates idle when both the NAV and RID (response indication deferral) counters are 0 or when either the NAV or RID counter is non-zero but the TA field of RTS frame 706 matches the saved TXOP holder address.

[0082] STA 704 may set an RA field of CTS frame 708 to a nonbandwidth signaling TA obtained from the TA field of RTS frame 706. STA 704 may set a Duration field of CTS frame 708 based on the Duration / ID field of RTS frame 706, namely as equal to the value of the Duration / ID field of RTS frame 706, adjusted by subtracting the time required to transmit CTS frame 708 and one SIFS period.

[0083] Upon receiving CTS frame 708, STA 702 may wait one SIFS period before transmitting data frame 710. STA 704 may transmit an ACK frame 712 in response to data frame 710. STA 704 may transmit ACK frame 712 one SIFS after receiving data frame 710

[0084] As shown in example 700, other STAs within communication range of STAs 702 and 704, and belonging to the same BSS, may set their NAVs according to RTS frame 706 and / or CTS frame 708. For example, a STA receiving RTS frame 706 may set its NAV based on the Duration / ID field of RTS frame 706. Another STA receiving CTS frame 708 may set its NAV based on the Duration field of CTS frame 708. As such, the other STAs may not access the channel using EDCA until the end of transmission of ACK frame 712.

[0085] FIG. 8 is an example 800 that illustrates a multi-user Request-to-Send (MU-RTS) / Clear-to-Send (CTS) procedure. Example 800 may be an example according to the MU-RTS / CTS procedure as defined in section 26.2.6 of the IEEE 802.1 1 standard draft. As shown in FIG. 8, example 800 may include an AP 802 and STAs 804 and 806. STAs 804 and 806 may be associated with AP 802. For the purpose of illustration, example 800 also illustrates STAs of an overlapping basic service set (OBSS) relative to the BSS of AP 802 (OBSS STAs). The OBSS STAs, as shown in FIG. 8, may be hidden from AP 802 (outside of the communication range of AP 802) or exposed to AP 802 (within the communication range of AP 802).Docket No.: 24-3052PCT

[0086] In example 800, AP 802 wishes to transmit a downlink (DL) multi-user (MU) PPDU 814 to STAs 804 and 806. DL MU PPDU 814 may comprise data for each of STAs 804 and 806. DL MU PPDU 814 may occupy a plurality of channels (e.g., 20 MHz channels). Each channel of the plurality of channels may carry the data for a respective STA (e.g., STA 804, STA 806) served by DL MU PPDU 814.

[0087] As shown in FIG. 8, to protect the transmission of DL MU PPDU 814 to STAs 804 and 806 from interference by OBSS STAs hidden from AP 802, AP 802 may use the MU-RTS / CTS procedure to initiate a TXOP and to protect the TXOP frame exchange sequence. AP 802 may initiate the TXOP by transmitting an MU-RTS trigger frame 808 that solicits simultaneous CTS frame transmissions from STAs 804 and 806.

[0088] MU-RTS trigger frame 808 may have a format as illustrated by MU-RTS trigger frame 500 illustrated in FIG. 5. As such, MU-RTS trigger frame 808 may comprise a frame control field, a duration field, an RA field, a TA field, a common info field, one or more user info fields, a padding field, and an FCS field. The duration field may be set to the time, in microseconds, required to transmit DL MU PPDU 814, plus the time required to transmit one CTS frame, one ACK frame (if required), and three SIPS periods.

[0089] The one or more user info fields correspond respectively to the one or more STAs solicited by the MU-RTS trigger frame. In example 800, MU-RTS trigger frame 808 may comprise a user info field for each of STAs 804 and 806 indicating that a CTS frame is solicited from each of STAs 804 and 806. As shown in FIG. 8, a user info field may comprise an AID12 subfield, an RU allocation subfield, reserved bits, and a PS 160 subfield. The AID12 subfield comprises an association identifier of the STA to which the user info field is addressed. The RU allocation subfield indicates a channel on which the solicited STA is to transmit the CTS frame. In an example, this may include a primary 20 MHz channel, a primary 40 MHz, a primary 80 MHz channel, a primary 160 MHz, an 80+80 Mhz channel, or a 320 MHz channel.

[0090] AP 802 may send MU-RTS trigger frame 808 in a PPDU that occupies one or more channels (e.g., 20 MHz channels). In an example, for each channel occupied by the PPDU that carries MU-RTS trigger frame 808, AP 802 may request at least one non-AP STA to send a CTS frame that occupies that channel. In an example, AP 802 may not request that a non-AP STA send a CTS frame that occupies a channel that is not occupied by the PPDU carrying MU-RTS trigger frame 808.

[0091] After transmitting MU-RTS trigger frame 808, AP 802 may wait for a CTSTimeout interval of aSIFSTime + aSlotTime + aRxPHYStartDelay that begins when a MAC layer of AP 802 receives a PHYTXEND. confirm primitive for transmitted MU-RTS trigger frame 808. If the MAC layer does not receive a PHY-RXEARLYSIG. indication or a PHY-RXSTART. indication primitive during the CTSTimeout interval, AP 802 may conclude that the transmission of MU-RTS trigger frame 808 has failed, and, if MU-RTS trigger frame 808 initiated a TXOP, AP 802 may invoke its backoff procedure. If the MAC layer receives a PHY- RXEARLYSIG. indication or a PHY-RXSTART. indication primitive during the CTSTimeout interval, then the MAC layer may wait for the corresponding PHY-RXEND. indication primitive to determine whether transmission of MU-RTS trigger frame 808 was successful. The receipt of a CTS frame from any non-APDocket No.: 24-3052PCTSTA addressed by MU-RTS trigger frame 808 before the PHY-RXEND. indication primitive shall be interpreted as the successful transmission of MU-RTS trigger frame 808, permitting the frame exchange sequence to continue. The receipt of any other type of frame shall be interpreted as a failure of the transmission of MU-RTS trigger frame 808. AP 802 may process the received frame and, if MU-RTS trigger frame 808 initiated a TXOP, AP 802 shall invoke its backoff procedure at the PHY-RXEND. indication primitive.

[0092] In example 800, on receiving MU-RTS trigger frame 808, STAs 804 and 806 respond by transmitting respectively CTS frames 810 and 812 to AP 802. In an example, STAs 804 and 806 begin the transmission of CTS frames 810 and 812, respectively, at the SIPS time boundary after an end of a received PPDU comprising MU-RTS trigger frame 808. In an example, STA 804 (or STA 806) responds to MU-RTS trigger frame 808 with a CTS frame when the following conditions are met: MU-RTS trigger frame 808 comprises a user info field addressed to the STA (the AID12 subfield of the user info field is equal to the 12 LSBs of the AID of the STA) and MU-RTS trigger frame 808 is sent by an AP with which the STA is associated; and the UL MU CS condition indicates that the medium is idle as described in section 26.5.2.5 (UL MU CS mechanism) of the IEEE 802.1 1 standard ("IEEE P802.11-REVme™ / D3.0, April 2023”). Otherwise, if one of the conditions is not met, STA 804 (or STA 806) does not send a CTS frame to AP 802.

[0093] In an example, STAs 804 and 806 may set an RA field of respectively CTS frames 810 and 812 to a TA obtained from the TA field of MU-RTS trigger frame 808. In an example, STAs 804 and 806 may set a duration field of respectively CTS frames 810 and 812 based on the duration field of MU-RTS trigger frame 808, namely as equal to the value of the duration field of MU-RTS trigger frame 808, adjusted by subtracting the time required to transmit respectively CTS frames 810 and 812 and one SIPS period.

[0094] OBSS STAs exposed to AP 802 may receive MU-RTS trigger frame 808 due to being within the communication range of AP 802. In an example, as shown in FIG. 8, on receiving MU-RTS trigger frame 808, OBSS STAs exposed to AP 802 set their respective NAVs based on the duration field of MU-RTS trigger frame 808. As such, the OBSS STAs exposed to AP 802 may not access the wireless medium for the duration of the TXOP initiated by AP 802.

[0095] OBSS STAs hidden from AP 802 do not receive MU-RTS trigger frame 808 due to being outside the communication range of AP 802. However, in an example, as shown in FIG. 8, some of the OBSS STAs hidden from AP 802 may receive CTS frame 810 and / or CTS frame 812 and may set their respective NAVs based on the duration field of CTS frame 810 and / or CTS frame 812. As such, some of the OBSS STAs hidden from AP 802 may also not access the wireless medium for the duration of the TXOP initiated by AP 802.

[0096] On receiving CTS frame 810 and / or CTS frame 812, AP 802 may wait one SIFS period before transmitting DL MU PPDU 814. On receiving DL MU PPDU 814, STAs 804 and 806 may respond by transmitting respective BlockAck (BA) frames 816 and 818 to AP 802.Docket No.: 24-3052PCT

[0097] It is envisioned in future IEEE 802.11 standards that a STA (AP STA or non-AP STA) may access a non-primary channel to communicate with another STA. Such operation may be referred to as non-primary channel access (NPCA) operation. Specifically, in addition to a default primary channel (which is used by all STAs in the BSS and via which the AP transmits management frames), the STA may have one or more secondary channels considered as NPCA primary channels. The STA may transmit or receive on a channel that includes an NPCA primary channel but that does not necessarily include the primary channel (e.g., when the primary channel is unavailable). The STA may maintain a NAV for an NPCA primary channel independent of the NAV associated with the primary channel. FIG. 9 shows an example that illustrates non-primary channel access (NPCA) operation. For the purpose of illustration, NPCA operation is contrasted with single primary channel (non-NPCA STA) operation. As shown in FIG. 9, the STA may be capable of operating over a plurality of channels. According to non-NPCA operation, the plurality of channels may include a primary channel (PCH), a first secondary channel (SCH1 ), a second secondary channel (SCH2), and a third secondary channel (SCH2). According to NPCA operation, the same channels may include a primary channel (PCH), a first secondary channel (SCH1), an NPCA primary channel (NPCA PCH), and a second secondary channel (SCH2). It is noted that the position of the NPCA primary channel may or may not be as shown in the example of FIG. 9. For example, the NPCA primary channel may correspond to SCH1 .

[0098] In an implementation, as shown in FIG. 10, in non-NPCA operation, a virtual carrier sense (CS) function (e.g., NAV) may be associated with only the PCH. Secondary channels may have only a physical CS function (e.g., energy detection) associated with them, which may be performed only when contending for transmission on the PCH. As such, as shown in FIG. 9, the STA may only transmit on a channel that includes the PCH (e.g., PCH, PCH+SCH1 , PCH+SCH1+SCH2, PCH+SCH1 +SCH2+SCH3) and only when the NAV associated with the PCH is zero (and the physical CS function indicates "channel idle" for all channels being used).

[0099] In contrast, as shown in FIG. 10, in NPCA operation, a virtual CS function (e.g., NAV) may be associated with multiple channels (e.g., PCH and NPCA PCH). As such, as shown in FIG. 9, the STA may transmit on channels that do not include the PCH but that include the NPCA PCH (e.g., NPCA PCH, NPCA PCH+SCH1 , NPCA PCH+SCH2) if the NAV associated with the NPCA PCH is zero (and the physical CS indicates “channel idle” for all channels being used). In an implementation, the STA may also transmit on channels that do not include the PCH but that include the NPCA PCH (e.g., NPCA PCH, NPCA PCH+SCH1 , NPCA PCH+SCH2) if the STA detects that the NPCA PCH is idle using physical CS for at least a medium synchronization duration.

[0100] In implementations, the STA may perform physical and / or virtual CS functions (herein referred to as CS or CCA) on multiple channels (e.g., PCH and NPCA PCH). If the PCH is busy (non-zero NAV or CCA indicates "channel busy”), the STA may use the NPCA PCH for transmission if the NPCA PCH is idle (zero NAV and CCA indicates “channel idle”).Docket No.: 24-3052PCT

[0101] In an implementation, the STA may perform CS in parallel on multiple channels, including the PCH and the NPCA PCH. Such a STA is referred to herein as a concurrent CCA NPCA STA (such a STA may also be referred to as a concurrent CCA multiple primary channel (MPC) STA or a Type 1 STA). Because of its concurrent CCA capability, a concurrent CCA NPCA STA is capable of medium synchronization simultaneously on multiple channels (e.g., PCH and NPCA PCH). Medium synchronization on a channel (e.g., PCH or NPCA PCH) may be performed by detecting a frame that includes NAV information or by listening to the channel for at least a medium synchronization duration and finding the channel idle throughout the medium synchronization duration. An NPCA STA that does not support this capability may perform CS on a single channel at a time. In an implementation, an NPCA STA may perform CS on the PCH by default, and when the PCH is found busy, the STA may perform CS on the NPCA PCH. Such a STA is referred to herein as a non-concurrent CCA NPCA STA (such a STA may also be referred to as a non-concurrent CCA MPC STA or a Type 2 STA). In contrast to the concurrent CCA NPCA STA, a non-concurrent CCA NPCA STA may only synchronize to the NPCA PCH after the PCH is found busy. Hence, it may need to listen to the channel for at least a medium synchronization duration (if it does not receive any frame that includes NAV information) before it is able to transmit.

[0102] FIG. 11 shows an example 1 100 that illustrates an NPCA operation. As shown in FIG. 11 , example 1 100 includes an AP and a STA associated with the AP. The AP and the STA may both support NPCA operation and may operate over a plurality of channels, including a primary channel (PCH), an NPCA primary channel (NPCA PCH), a first secondary channel (SCH1), and a second secondary channel (SCH2).

[0103] Example 1100 may begin with the AP transmitting a frame 1 102 on the PCH. Frame 1102 may indicate a medium synchronization duration for the NPCA PCH. The medium synchronization duration of a channel indicates a minimum duration that a STA must listen to the channel before the STA is able to transmit on the channel (if the STA does not receive via the channel before the end of the medium synchronization duration a frame that indicates NAV information). Frame 1 102 may be a management frame, such as a beacon frame, for example.

[0104] Subsequently, while the AP and STA operate on the PCH, transmission of a frame 1104 from an OBSS may begin on the PCH. The AP and the STA may detect frame 1 104 on the PCH. In an implementation, the AP and STA may be configured to set a NAV associated with the PCH based on receiving frame 1 104 on the PCH. Frame 1104 may indicate a transmission (of one or more frames including frame 1104) on the PCH. A duration of the transmission on the PCH may be provided by a duration field of frame 1 104, a transmission opportunity (TXOP) duration field of an inter-BSS PPDU comprising frame 1104, or a length field of the inter-BSS PPDU. The AP and STA may set their NAVs for the PCH based on the duration of the OBSS transmission on the PCH (hereinafter, OBSS NAV duration or OBSS TXOP duration).

[0105] In accordance with NPCA operation, on receiving an inter-BSS PPDU and obtaining the OBSS NAV duration, the AP and the STA may be configured to switch to the NPCA PCH for the OBSS NAV duration. InDocket No.: 24-3052PCT an example, the AP and the STA may switch to the NPCA PCH at time T 1 as shown in example 1100. Here, time T1 may correspond to the time for switching from the PCH to the NPCA PCH after obtaining the OBSS NAV duration. The AP and STA may be configured to finish transmitting on the NPCA PCH before an end of the OBSS NAV duration and to return to the PCH by the end of the OBSS NAV duration, by time T2, as shown in example 1100. Here, time T2 may correspond to the time for switching from the NPCA PCH to the PCH by the end of OBSS NAV duration.

[0106] In an implementation, after switching to the NPCA PCH, the AP and STA may start a “MediumSyncDelay” timer for the medium synchronization duration of the NPCA PCH (e.g., as indicated in frame 1 102). In example 1 100, the AP may be a concurrent CCA STA capable of concurrent CS on both the PCH and the NPCA PCH. As such, provided that the NPCA PCH is idle, the AP may access the NPCA PCH, without waiting for expiration of the “MediumSyncDelay" timer, to transmit a frame 1 106 on the NPCA PCH. In an example, the STA may be a non-concurrent CCA STA. On switching to the NPCA PCH, the STA may not be aware of whether a transmission is ongoing on the NPCA PCH. The STA may thus be configured to sense the NPCA PCH until the “MediumSyncDelay” timer expires before attempting to access the NPCA PCH. However, the STA may acquire medium synchronization on the NPCA PCH before expiration of the “MediumSyncDelay” timer if the STA receives a frame indicating NAV information on the NPCA PCH. For example, the STA may acquire medium synchronization on the NPCA PCH on receiving frame 1106 from the AP. The STA may reset the “MediumSyncDelay” timer to zero and may then proceed to access the NPCA PCH, after performing a random backoff, to transmit a frame (not shown in FIG. 11 ) on the NPCA PCH.

[0107] FIG. 12 illustrates an example 1200 that highlights a problem that may arise in existing NPCA operation. As shown in FIG. 12, example 1200 includes STAs 1202, 1204 and 1206. STAs 1204 and 1206 may belong to the same BSS. STA 1202 may belong to a different BSS than STAs 1204 and 1206. In an example, STA 1202 may be an AP STA, STA 1204 may be an AP STA, and STA 1206 may be a non-AP STA. In an example, where STA 1204 is an AP STA and STA 1206 is a non-AP STA, STA 1206 may be associated with STA 1204. In an example, STAs 1202 and 1204 may support NPCA operation and may operate over a plurality of channels, including a primary channel (PCH), an NPCA primary channel (NPCA PCH), a first secondary channel (SCH1), and a second secondary channel (SCH2). In an example, STA 1206 may not support NPCA operation and may operate only over PCH.

[0108] As shown in FIG. 12, example 1200 may begin with STA 1202 transmitting a frame 1210 on the PCH. By transmitting frame 1210, STA 1202 may obtain a TXOP on the PCH. Frame 1210 may be comprised in a PPDU comprising a TXOP duration field. The TXOP duration field may indicate a TXOP duration 1212. TXOP duration 1212 may indicate a duration that starts by the end of frame 1210 (e.g., starting at a time T1) and that ends at a time T2 as shown in FIG. 12.

[0109] In an example, on receiving frame 1210, STA 1204 may determine that frame 1210 is comprised in an inter-BSS PPDU (OBSS PPDU). As discussed above in relation to FIG. 11 and in accordance with NPCADocket No.: 24-3052PCT operation, STA 1204 may set a NAV 1214 for the PCH based on TXOP duration 1212 and may switch to the NPCA PCH for TXOP duration 1212 (OBSS NAV duration for STA 1204). In example 1200, STA 1204 may switch to the NPCA PCH at a time T1. After switching to the NPCA PCH, STA 1204 may start a “MediumSyncDelay” timer for the medium synchronization duration of the NPCA PCH, and if the NPCA PCH is idle (at / after expiration of the MediumSyncDelay timer), STA 1204 may access the NPCA PCH to transmit a frame on the NPCA PCH (not shown in FIG. 12). In an example, STA 1204 may perform uplink and / or downlink communications via the NPCA PCH as illustrated by frame exchange 1215 in example 1200. In an example, frame exchange 1215 may end before an end of TXOP duration 1212. In an example, where STA 1204 is an AP STA, STA 1204 may communicate with its associated STAs via the NPCA PCH during TXOP duration 1212 and may be configured to switch back to the PCH by the end of TXOP duration 1212.

[0110] In an example, on receiving frame 1210, STA 1206 may determine that frame 1210 is comprised in an inter-BSS PPDU (OBSS PPDU). Based on not supporting / enabling NPCA operation, STA 1206 may set a NAV 1216 for the PCH based on TXOP duration 1212 but may not switch to the NPCA PCH. Instead, STA 1206 remains on the PCH and remains silent until an end of TXOP duration 1212 (e.g., T2).

[0111] After transmitting frame 1210, STA 1202 may communicate with its associated STAs via the PCH within TXOP duration 1212. In an example, STA 1202 may perform uplink and / or downlink communications as illustrated with a frame exchange 1218. In an example (not shown in FIG. 12), frame exchange 1218 may extend to the end of TXOP duration 1212. In another example, as illustrated in example 1200, STA 1202 and its associated STAs may finish communicating before the end of TXOP duration 1212, and frame exchange 1218 may end before the end of TXOP duration 1212. In accordance with existing IEEE 802.11 operation, based on frame exchange 1218 ending before the end of TXOP duration 1212, STA 1202 may transmit a frame 1220 to truncate the TXOP obtained by STA 1202 on the PCH. In an example, frame 1220 may be a contention free-end (CF-end) frame. In example 1200, STA 1202 may transmit frame 1220 at a time T3, ending / truncating the TXOP on the PCH, as illustrated in example 1200, before the end of TXOP duration 1212 (e.g., time T2).

[0112] With the TXOP truncated, the PCH becomes available for contention by any STA operating on the PCH. Specifically, on receiving frame 1220, STA 1206 may reset NAV 1216 at time T3, earlier than the end of TXOP duration 1212. STA 1206 may then contend for the PCH and transmit a frame 1222 on the PCH. In an example, STA 1206 may be associated with STA 1204 and may transmit frame 1222 to STA 1204. However, as STA 1204 is configured to switch to the PCH by the end of TXOP duration 1212, STA 1204 may still be operating on the NPCA PCH (despite having finished communication on the NPCA PCH) when STA 1206 transmits frame 1222. Accordingly, STA 1204 may not receive frame 1222 and STA 1206 may not receive a response to frame 1222 from STA 1206. STA 1206 may attempt re-transmission of frame 1222 on the PCH without response from STA 1204. This may result in several unsuccessful frame exchange attempts on the PCH, wasting both PCH resources and power / p recessing resources of STA 1206. Additionally, STADocket No.: 24-3052PCT1206 may have low latency traffic to transmit to STA 1204. Transmission of the low latency traffic to STA 1204 may be delayed and the low latency traffic may be discarded or lost.

[0113] Embodiments of the present disclosure, as further described below, address the above-discussed problem of existing technologies. In an aspect, a first STA transmits, via a first channel, a first frame that truncates a TXOP obtained by the first STA on the first channel. The first STA also transmits, via a second channel, a second frame indicating / informing truncation of the TXOP on the first channel. In an embodiment, the first channel comprises a PCH. In an embodiment, the second channel comprises an NPCA PCH, an aggregate channel comprising the PCH and the NPCA PCH, a backhaul channel, or a control channel. In an embodiment, the transmitting of the second frame is after the transmitting of the first frame. In another embodiment, the transmitting of the second frame is before the transmitting of the first frame. In an embodiment, transmitting the second frame comprises transmitting the second frame to a second STA (operating on a third channel, e g., NPCA PCH). On receiving the second frame, the second STA switches to the first channel. As such, the second STA may contend for the first channel after the truncation of the TXOP and may communicate on the first channel. Additionally, where the second STA comprises an AP STA, the second STA may receive any frame transmitted by an associated STA on the first channel after truncation of the TXOP on the first channel. In an embodiment, where the second STA comprises an AP STA, the second STA may further transmit, via the third channel (e.g., NPCA PCH), a third frame announcing / indicating switching, by the second STA, from the third channel to the first channel (e.g., PCH). As such, stations associated with the second STA may also switch to the first channel before an end of the TXOP on the first channel and may communicate with the second STA on the first channel. In an embodiment, the first STA may be configured not to truncate / terminate a TXOP, on the first channel, obtained by the first STA, before an end of a duration of the TXOP. In an embodiment, the first STA may be configured not to truncate the TXOP, on the first channel, obtained by the first STA, before an end of a duration of the TXOP, based on a second STA supporting / enabling NPCA operation.

[0114] FIG. 13 shows an example 1300 that illustrates an example NPCA operation according to an embodiment. As shown in FIG. 13, example 1300 includes STAs 1302, 1304 and 1306. STAs 1304 and 1306 may belong to the same BSS. STA 1302 may belong to a different BSS than STAs 1304 and 1306. Each of STAs 1302, 1304 and 1306 may be an AP STA or a non-AP STA. In an embodiment, STA 1302 may be an AP STA, STA 1304 may be an AP STA, and STA 1306 may be a non-AP STA, or vice versa. In an embodiment, where STA 1304 is an AP STA and STA 1306 is a non-AP STA, STA 1306 may be associated with STA 1304. In an embodiment, STAs 1302 and 1304 may support NPCA operation and may operate over a plurality of channels, including a primary channel (PCH), an NPCA primary channel (NPCA PCH), a first secondary channel (SCH1 ), and a second secondary channel (SCH2). In an embodiment, STA 1306 may not support NPCA operation and may operate only over the PCH. In an embodiment, where STA 1306 does not support NPCA operation, STA 1306 may be a non-ultra-high reliability (non-UHR) STA, such as anDocket No.: 24-3052PCT extremely high throughput (EHT) STA, a high efficiency (HE) STA, a very high throughput (VHT) STA, or a high throughput (HT) STA. In another embodiment, STA 1306 may support NPCA operation but may have disabled / deacti vated NPCA operation and may thus operate only over the PCH. In such an embodiment, STA 1306 may be a UHR STA.

[0115] As shown in FIG. 13, example 1300 may begin with STA 1302 transmitting a frame 1310 on the PCH. By transmitting frame 1310, STA 1302 may initiate and / or obtain a TXOP on the PCH. Frame 1310 may be comprised in a PPDU comprising a TXOP duration field. The TXOP duration field may indicate a TXOP duration 1312. TXOP duration 1312 may indicate a duration that starts by the end of frame 1310 (e.g., starting at a time T1), and that ends at a time T2 as shown in FIG. 13.

[0116] In an embodiment, on receiving frame 1310, STA 1304 may determine that frame 1310 is comprised in an inter-BSS PPDU (OBSS PPDU). As discussed above in relation to FIG. 11 and in accordance with NPCA operation, STA 1304 may set a NAV 1314 for the PCH based on TXOP duration 1312 and may switch to the NPCA PCH for TXOP duration 1312 (OBSS NAV duration for STA 1304). In example 1300, STA 1304 may switch to the NPCA PCH at a time T1 . After switching to the NPCA PCH, STA 1304 may start a “MediumSyncDelay” timer for the medium synchronization duration of the NPCA PCH, and if the NPCA PCH is idle (at / after expiration of the MediumSyncDelay timer), STA 1304 may access the NPCA PCH to transmit a frame on the NPCA PCH (not shown in FIG. 13). In an example, STA 1304 may perform uplink and / or downlink communications via the NPCA PCH as illustrated by a frame exchange 1315 in example 1300. In an example, frame exchange 1315 may end before an end of TXOP duration 1312. In an example, where STA 1304 is an AP STA, STA 1304 may communicate with its associated STAs via the NPCA PCH during TXOP duration 1312 and may be configured to switch back to the PCH by the end of TXOP duration 1312.

[0117] In an embodiment, on receiving frame 1310, STA 1306 may determine that frame 1310 is comprised in an inter-BSS PPDU (OBSS PPDU). Based on not supporting / enabling NPCA operation, STA 1306 may set a NAV 1316 for the PCH based on TXOP duration 1312 but may not switch to the NPCA PCH. Instead, STA 1306 remains on the PCH and remains silent until an end of TXOP duration 1312 (e.g., T2).

[0118] After transmitting frame 1310, STA 1302 may communicate with its associated STAs on the PCH within TXOP duration 1312. In an example, STA 1302 may perform uplink and / or downlink communications as illustrated with a frame exchange 1318. In an example (not shown in FIG. 13), frame exchange 1318 may extend to the end of TXOP duration 1312. In another example, as illustrated in example 1300, STA 1302 and its associated STAs may finish communicating before the end of TXOP duration 1312, and frame exchange 1318 may end before the end of TXOP duration 1312. In accordance with existing IEEE 802.11 operation, based on frame exchange 1318 ending before the end of TXOP duration 1312, STA 1302 may transmit a frame 1320 to truncate the TXOP obtained by STA 1302 on the PCH . In an embodiment, frame 1320 may be a contention free-end (CF-end) frame. In example 1300, STA 1302 may transmit frame 1320 at a time T3, ending / truncating the TXOP on the PCH, as illustrated in example 1300, before the end of TXOP durationDocket No.: 24-3052PCT1312 (e.g., time T2). With the TXOP truncated, the PCH becomes available for contention by any STA operating on the PCH.

[0119] On receiving frame 1320, STA 1306 may reset NAV 1316 at time T3, earlier than the end of the OBSS NAV duration. In an embodiment, STA 1306 may be a UHR STA. In an embodiment, being a non-AP STA, STA 1306 may be configured to perform only triggered uplink transmission on the PCH after resetting NAV 1316 at time T3. In another embodiment, after resetting NAV 1316 at time T3, STA 1306 may be configured to wait until an end of TXOP duration 1312 to contend for the channel (despite that the TXOP associated with TXOP duration 1312 has been reset). This embodiment assumes that the UHR AP with which (UHR) STA 1306 is associated may still be operating / communicating on the NPCA PCH until the end of TXOP duration 1312. In another embodiment, STA 1306 may be a non-UHR STA. As such, after resetting NAV 1316 at time T3, STA 1306 may contend for the PCH if STA 1306 has buffered traffic (not shown in FIG. 13). Otherwise, if STA 1306 does not have buffered traffic, STA 1306 may not contend for the PCH.

[0120] In an embodiment, after transmitting frame 1320, STA 1302 may be configured to transmit a frame (before an end of the TXOP) indicating / informing truncation of the TXOP on the PCH. In an embodiment, as illustrated in FIG. 13, after transmitting frame 1320, STA 1302 may transmit a frame 1322, via the NPCA PCH, indicating / informing truncation of the TXOP on the PCH. In an embodiment, as illustrated in FIG. 13, based on transmitting frame 1320, STA 1302 may transmit a frame 1322, via the NPCA PCH, indicating / informing truncation of the TXOP on the PCH. Alternatively, as illustrated in FIG. 14, STA 1302 may transmit a frame 1422, via an aggregate channel comprising the PCH and the NPCA PCH, indicating / informing truncation of the TXOP on the PCH. Frame 1322 or frame 1422 may indicate that the truncation of the TXOP is completed or that the TXOP on the PCH has been truncated In an embodiment, frame 1322 or frame 1422 may indicate the time at which the TXOP on the PCH has been truncated. In example 1300, the transmitting of frame 1322 is after the transmitting of frame 1320. In example 1400, the transmitting of frame 1422 is after the transmitting of frame 1320. Frame 1422 may duplicate the same information on the PCH and on the NPCA PCH. As such, frame 1422 may duplicate the indication / information of truncation of the TXOP on the PCH in each channel (including the NPCA PCH). In an embodiment, STA 1302 may perform a clear channel assessment (CCA) before transmitting frame 1322 or frame 1422. In an embodiment, the CCA may use a first backoff counter value smaller than a second backoff counter used by another STA (not shown in FIG. 13 or in FIG. 14). In an embodiment, the other STA may be a member of a BSS of STA 1302. In another embodiment, the other STA may be a member of an OBSS. In example 1300, STA 1302 transmits frame 1322 after determining that the NPCA PCH is idle. In an embodiment, frame 1322 may comprise a management frame, an action frame, a control frame, a quality of service (QoS) null frame, or a QoS data frame. In example 1400, STA 1302 transmits frame 1422 after determining that the aggregate channel is idle. In an embodiment, frame 1422 may comprise a management frame, an action frame, a control frame, a quality of service (QoS) null frame, or a QoS data frame.Docket No.: 24-3052PCT

[0121] In an embodiment, STA 1302 may transmit frame 1322 or frame 1422 addressed to STA 1304, where STA 1304 operates / camps on the NPCA PCH, during the TXOP on the PCH. For example, both STA 1302 and STA 1304 may comprise an AP STA, and STA 1302 may address frame 1322 or frame 1422 to STA 1304 only to inform STA 1304 of the truncation of the TXOP on PCH. In another embodiment, frame 1322 or frame 1422 may comprise a broadcast frame. As such, STA 1302, which may be an AP STA or a non-AP STA, may inform STA 1304, which may be an AP STA or a non-AP STA, and any other STA, of the truncation of the TXOP on PCH.

[0122] On receiving frame 1322 or frame 1422, STA 1304 may determine that the TXOP obtained by STA 1302 on the PCH is (or has been) truncated (e.g., truncation of the TXOP is completed). In an embodiment, based on receiving frame 1322 or frame 1422, STA 1304 may switch from the NPCA PCH to the PCH. In an embodiment, STA 1304 may switch from the NPCA PCH to the PCH after finishing any ongoing communication on the NPCA PCH. In an embodiment, based on receiving frame 1322 or frame 1422, STA 1304 may further reset NAV 1314 for the PCH. In an embodiment, STA 1304 may reset NAV 1314 before switching to the PCH. In another embodiment, STA 1304 may reset NAV 1314 after switching to the PCH.

[0123] In an embodiment, where STA 1304 comprises an AP STA, STA 1304 may further transmit (e.g., before switching to the PCH), via the NPCA PCH, a frame 1324 announcing / indicating switching, by STA 1304, from the NPCA PCH to the PCH. In an embodiment, STA 1304 may perform a clear channel assessment (CCA) before transmitting frame 1324 and may transmit frame 1324 based on the NPCA PCH being idle. In an embodiment, frame 1324 may comprise a management frame, an action frame, a control frame, a quality of service (QoS) null frame, or a QoS data frame. In an embodiment, frame 1324 may comprise a broadcast frame. As such, STAs associated with STA 1304 and that are operating on the NPCA PCH may switch from the NPCA PCH to the PCH. In another embodiment, frame 1324 may comprise a frame addressed to another STA (not shown in FIG. 13 or in FIG. 14), where the other STA is associated with STA 1304. As such, only the STA to which frame 1324 is addressed may switch from the NPCA PCH to the PCH. After transmitting frame 1324, STA 1304 may switch from the NPCA PCH to PCH.

[0124] In another embodiment, where STA 1304 comprises a non-AP STA, STA 1304 may not announce the switching of STA 1304 from the NPCA PCH to the PCH and may only switch from the NPCA PCH to the PCH, based on receiving frame 1322 or frame 1422.

[0125] After switching to the PCH, STA 1304 may perform a CCA before transmitting frame 1326 via the PCH and may transmit frame 1326 based on the PCH being idle. As such, by being informed by STA 1302 of the truncation of the TXOP on the PCH, STA 1304 may communicate with its associated STAs (e.g., STA 1306) via the PCH, after the truncation of the TXOP obtained by STA 1302 on the PCH.

[0126] FIG. 15 shows another example 1500 that illustrates an example NPCA operation according to an embodiment. As shown in FIG. 15, example 1500 includes STAs 1502, 1504 and 1506. STAs 1504 and 1506 may belong to the same BSS. STA 1502 may belong to a different BSS than STAs 1504 and 1506. Each ofDocket No.: 24-3052PCTSTAs 1502, 1504 and 1506 may be an AP STA or a non-AP STA. In an embodiment, STA 1502 may be an AP STA, STA 1504 may be an AP STA, and STA 1506 may be a non-AP STA, or vice versa. In an embodiment, where STA 1504 is an AP STA and STA 1506 is a non-AP STA, STA 1506 may be associated with STA 1504. In an embodiment, STAs 1502 and 1504 may support NPCA operation and may operate over a plurality of channels, including a primary channel (PCH), an NPCA primary channel (NPCA PCH), a first secondary channel (SCH1 ), a second secondary channel (SCH2), and a reserved channel. In an embodiment, the reserved channel may comprise a backhaul channel. In another embodiment, the reserved channel may comprise a control channel. In an embodiment, STA 1506 may not support NPCA operation and may operate only over the PCH. In an embodiment, where STA 1506 does not support NPCA operation, STA 1506 may be a non-ultra-high reliability (non-UHR) STA, such as an extremely high throughput (EHT) STA, a high efficiency (HE) STA, a very high throughput (VHT) STA, or a high throughput (HT) STA. In another embodiment, STA 1506 may support NPCA operation but may have disabled / deactivated NPCA operation and may thus operate only over the PCH. In such an embodiment, STA 1506 may be a UHR STA.

[0127] As shown in FIG. 15, example 1500 may begin with STA 1502 transmitting a frame 1510 on the PCH. By transmitting frame 1510, STA 1502 may initiate and / or obtain a TXOP on the PCH. Frame 1510 may be comprised in a PPDU comprising a TXOP duration field. The TXOP duration field may indicate a TXOP duration 1512. TXOP duration 1512 may indicate a duration that starts by the end of frame 1510 (e.g., starting at a time T1), and that ends at a time T2 as shown in FIG. 15.

[0128] In an embodiment, on receiving frame 1510, STA 1504 may determine that frame 1510 is comprised in an inter-BSS PPDU (OBSS PPDU). As discussed above in relation to FIG. 11 and in accordance with NPCA operation, STA 1504 may set a NAV 1514 for the PCH based on TXOP duration 1512 and may switch to the NPCA PCH for TXOP duration 1512 (OBSS NAV duration for STA 1504). In example 1500, STA 1504 may switch to the NPCA PCH at a time T1 . After switching to the NPCA PCH, STA 1504 may start a “MediumSyncDelay” timer for the medium synchronization duration of the NPCA PCH, and if the NPCA PCH is idle (at / after expiration of the MediumSyncDelay timer), STA 1504 may access the NPCA PCH to transmit a frame on the NPCA PCH (not shown in FIG. 15). In an example, STA 1504 may perform uplink and / or downlink communications via the NPCA PCH as illustrated by a frame exchange 1515 in example 1500. In an example, frame exchange 1515 may end before an end of TXOP duration 1512. In an example, where STA 1504 is an AP STA, STA 1504 may communicate with its associated STAs via the NPCA PCH during TXOP duration 1512 and may be configured to switch back to the PCH by the end of TXOP duration 1512.

[0129] In an embodiment, on receiving frame 1510, STA 1506 may determine that frame 1510 is comprised in an inter-BSS PPDU (OBSS PPDU). Based on not supporting / enabling NPCA operation, STA 1506 may set a NAV 1516 for the PCH based on TXOP duration 1512 but may not switch to the NPCA PCH. Instead, STA 1506 remains on the PCH and remains silent until an end of TXOP duration 1512 (e.g., T2).Docket No.: 24-3052PCT

[0130] After transmitting frame 1510, STA 1502 may communicate with its associated STAs via the PCH within TXOP duration 1512. In an example, STA 1502 may perform uplink and / or downlink communications as illustrated with a frame exchange 1518. In an example (not shown in FIG. 15), frame exchange 1518 may extend to the end of TXOP duration 1512. In another example, as illustrated in example 1500, STA 1502 and its associated STAs may finish communicating before the end of TXOP duration 1512, and frame exchange 1518 may end before the end of TXOP duration 1512. In accordance with existing IEEE 802.11 operation, based on frame exchange 1518 ending before the end of TXOP duration 1512, STA 1502 may transmit a frame 1520 to truncate the TXOP obtained by STA 1502 on the PCH . In an embodiment, frame 1520 may be a contention free-end (CF-end) frame. In example 1500, STA 1502 may transmit frame 1520 at a time T3, ending / truncating the TXOP on the PCH, as illustrated in example 1500, before the end of TXOP duration 1512 (e.g., time T2). With the TXOP truncated, the PCH becomes available for contention by any STA operating on the PCH.

[0131] On receiving frame 1520, STA 1506 may reset NAV 1516 at time T3, earlier than the end of the OBSS NAV duration. In an embodiment, STA 1506 may be a UHR STA. In an embodiment, being a non-AP STA, STA 1506 may be configured to perform only triggered uplink transmission on the PCH after resetting NAV 1516 at time T3. In another embodiment, after resetting NAV 1516 at time T3, STA 1506 may be configured to wait until an end of TXOP duration 1512 to contend for the channel (despite that the TXOP associated with TXOP duration 1512 has been reset). This embodiment assumes that the UHR AP with which (UHR) STA 1506 is associated may still be operating / communicating on the NPCA PCH until the end of TXOP duration 1512. In another embodiment, STA 1506 may be a non-UHR STA. As such, after resetting NAV 1516 at time T3, STA 1506 may contend for the PCH if STA 1506 has buffered traffic (not shown in FIG. 15). Otherwise, if STA 1506 does not have buffered traffic, STA 1506 may not contend for the PCH.

[0132] In an embodiment, after transmitting frame 1520, STA 1502 may be configured to transmit a frame (before an end of the TXOP) indicating / informing truncation of the TXOP on the PCH. In an embodiment, as illustrated in FIG. 15, after transmitting frame 1520, STA 1502 may transmit a frame 1522, via the reserved channel, indicating / informing truncation of the TXOP on the PCH . In an embodiment, the reserved channel may comprise a backhaul channel. In another embodiment, the reserved channel may comprise a control channel. Frame 1522 may indicate that the truncation of the TXOP is completed or that the TXOP on the PCH has been truncated. In an embodiment, frame 1522 may indicate the time at which the TXOP on the PCH has been truncated. In example 1500, the transmitting of frame 1522 is after the transmitting of frame 1520. In an embodiment, STA 1502 may perform a clear channel assessment (CCA) before transmitting frame 1522. In an embodiment, the CCA may use a first backoff counter value smaller than a second backoff counter used by another STA (not shown in FIG. 15). In an embodiment, the other STA may be a member of a BSS of STA 1502. In another embodiment, the other STA may be a member of an OBSS. In example 1500, STA 1502 transmits frame 1522 after determining that the reserved channel is idle. In an embodiment, frameDocket No.: 24-3052PCT1522 may comprise a management frame, an action frame, a control frame, a quality of service (QoS) null frame, or a QoS data frame.

[0133] In an embodiment, STA 1502 may transmit frame 1522 addressed to STA 1504, where STA 1504 operates / camps on the NPCA PCH, during the TXOP on the PCH. In addition, STA 1504 also operates on the reserved channel. For example, both STA 1502 and STA 1504 may comprise an AP STA, and STA 1502 may address frame 1522 to STA 1504 only to inform STA 1304 of the truncation of the TXOP on PCH.

[0134] On receiving frame 1522, STA 1504 may determine that the TXOP obtained by STA 1502 on the PCH is (or has been) truncated (e.g., truncation of the TXOP is completed). In an embodiment, based on receiving frame 1522, STA 1504 may switch from the NPCA PCH to the PCH. In an embodiment, STA 1504 may switch from the NPCA PCH to the PCH after finishing any ongoing communication on the NPCA PCH. In an embodiment, based on receiving frame 1522, STA 1504 may further reset NAV 1514 for the PCH. In an embodiment, STA 1504 may reset NAV 1514 before switching to the PCH. In another embodiment, STA 1504 may reset NAV 1514 after switching to the PCH.

[0135] In an embodiment, where STA 1504 comprises an AP STA, STA 1504 may further transmit (e.g., before switching to the PCH), via the NPCA PCH, a frame 1524 announcing / indicating switching, by STA 1504, from the NPCA PCH to the PCH. In an embodiment, STA 1504 may perform a clear channel assessment (CCA) before transmitting frame 1524 and may transmit frame 1524 based on the NPCA PCH being idle. In an embodiment, frame 1524 may comprise a management frame, an action frame, a control frame, a quality of service (QoS) null frame, or a QoS data frame. In an embodiment, frame 1524 may comprise a broadcast frame. As such, STAs associated with STA 1504 and that are operating on the NPCA PCH may switch from the NPCA PCH to the PCH. In another embodiment, frame 1524 may comprise a frame addressed to another STA (not shown in FIG. 15), where the other STA is associated with STA 1504. As such, only the STA to which frame 1524 is addressed may switch from the NPCA PCH to the PCH. After transmitting frame 1524, STA 1504 may switch from the NPCA PCH to the PCH.

[0136] After switching to the PCH, STA 1504 may perform a CCA before transmitting frame 1526 via the PCH and may transmit frame 1526 based on the PCH being idle. As such, by being informed by STA 1502 of the truncation of the TXOP on the PCH, STA 1504 may communicate with its associated STAs (e.g., STA 1506) via the PCH, after the truncation of the TXOP obtained by STA 1502 on the PCH.

[0137] FIG. 16 shows another example 1600 that illustrates an example NPCA operation according to an embodiment As shown in FIG. 16, example 1600 includes STAs 1602, 1604 and 1606. STAs 1604 and 1606 may belong to the same BSS. STA 1602 may belong to a different BSS than STAs 1604 and 1606. Each of STAs 1602, 1604 and 1606 may be an AP STA or a non-AP STA. In an embodiment, STA 1602 may be an AP STA, STA 1604 may be an AP STA, and STA 1606 may be a non-AP STA, or vice versa. In an embodiment, where STA 1604 is an AP STA and STA 1606 is a non-AP STA, STA 1606 may be associated with STA 1604. In an embodiment, STAs 1602 and 1604 may support NPCA operation and may operate overDocket No.: 24-3052PCT a plurality of channels, including a primary channel (PCH), an NPCA primary channel (NPCA PCH), a first secondary channel (SCH1 ), and a second secondary channel (SCH2). In an embodiment, STA 1606 may not support NPCA operation and may operate only over the PCH. In an embodiment, where STA 1606 does not support NPCA operation, STA 1606 may be a non-ultra-high reliability (non-UHR) STA, such as an extremely high throughput (EHT) STA, a high efficiency (HE) STA, a very high throughput (VHT) STA, or a high throughput (HT) STA. In another embodiment, STA 1606 may support NPCA operation but may have disabled / deactivated NPCA operation and may thus operate only over the PCH. In such an embodiment, STA 1606 may be a UH STA.

[0138] As shown in FIG. 16, example 1600 may begin with STA 1602 transmitting a frame 1610 on the PCH. By transmitting frame 1610, STA 1602 may initiate and / or obtain a TXOP on the PCH. Frame 1610 may be comprised in a PPDU comprising a TXOP duration field. The TXOP duration field may indicate a TXOP duration 1612. TXOP duration 1612 may indicate a duration that starts by the end of frame 1610 (e g., starting at a time T1), and that ends at a time T2 as shown in FIG. 16.

[0139] In an embodiment, on receiving frame 1610, STA 1604 may determine that frame 1610 is comprised in an inter-BSS PPDU (OBSS PPDU). As discussed above in relation to FIG. 11 and in accordance with NPCA operation, STA 1604 may set a NAV 1614 for the PCH based on TXOP duration 1612 and may switch to the NPCA PCH for TXOP duration 1612 (OBSS NAV duration for STA 1604). In example 1600, STA 1604 may switch to the NPCA PCH at a time T1 . After switching to the NPCA PCH, STA 1604 may start a “MediumSyncDelay” timer for the medium synchronization duration of the NPCA PCH, and if the NPCA PCH is idle (at / after expiration of the MediumSyncDelay timer), STA 1604 may access the NPCA PCH to transmit a frame on the NPCA PCH (not shown in FIG. 16). In an example, STA 1604 may perform uplink and / or downlink communications via the NPCA PCH as illustrated by frame exchange 1615 in example 1600. In an example, frame exchange 1615 may end before an end of TXOP duration 1612. In an example, where STA 1604 is an AP STA, STA 1604 may communicate with its associated STAs via the NPCA PCH during TXOP duration 1612 and may be configured to switch back to the PCH by the end of TXOP duration 1612.

[0140] In an embodiment, on receiving frame 1610, STA 1606 may determine that frame 1610 is comprised in an inter-BSS PPDU (OBSS PPDU). Based on not supporting / enabling NPCA operation, STA 1606 may set a NAV 1616 for the PCH based on TXOP duration 1612 but may not switch to the NPCA PCH. Instead, STA 1606 remains on the PCH and remains silent until an end of TXOP duration 1612 (e.g., T2).

[0141] After transmitting frame 1610, STA 1602 may communicate with its associated STAs via the PCH within TXOP duration 1612. In an example, STA 1602 may perform uplink and / or downlink communications as illustrated with a frame exchange 1618. In an example (not shown in FIG. 16), frame exchange 1618 may extend to the end of TXOP duration 1612. In another example, as illustrated in example 1600, STA 1602 and its associated STAs may finish communicating before the end of TXOP duration 1612, and frame exchange 1618 may end before the end of TXOP duration 1612. In an embodiment, STA 1602 may be configured toDocket No.: 24-3052PCT transmit a frame indicating / informing truncation of the TXOP obtained by STA 1602 on the PCH, before transmitting a frame to truncate the TXOP on the PCH. In an embodiment, before transmitting a frame to truncate the TXOP on the PCH, STA 1602 may transmit, via the NPCA PCH, a frame 1620 indicating / informing truncation of the TXOP on the PCH. In an embodiment, frame 1620 may indicate a transmission time of the frame to truncate TXOP on the PCH (e.g., transmission time of a frame 1624). In an embodiment, the transmitting of frame 1620 may be during frame exchange 1618. In an embodiment, the transmitting of frame 1620 is before the end of TXOP duration 1612.

[0142] In an embodiment, STA 1602 may perform a clear channel assessment (CCA) before transmitting frame 1620. In an embodiment, the CCA may use a first backoff counter value smaller than a second backoff counter used by another STA (not shown in FIG. 16). In an embodiment, the other STA may be a member of a BSS of STA 1602. In another embodiment, the other STA may be a member of an OBSS. In example 1600, STA 1602 transmits frame 1620 after determining that the NPCA PCH is idle. In an embodiment, frame 1620 may comprise a management frame, an action frame, a control frame, a quality of service (QoS) null frame, or a QoS data frame.

[0143] In an embodiment, STA 1602 may transmit frame 1620 addressed to STA 1604, where STA 1604 operates / camps on the NPCA PCH, during the TXOP on the PCH. For example, both STA 1602 and STA 1604 may comprise an AP STA, and STA 1602 may address frame 1620 to STA 1604 only to inform STA 1604 of the truncation of the TXOP on PCH. In another embodiment, frame 1620 may comprise a broadcast frame. As such, STA 1602, which may be an AP STA or a non-AP STA, may inform STA 1604, which may be an AP STA or a non-AP STA, and any other STA, of the truncation of the TXOP on PCH.

[0144] On receiving frame 1620, STA 1604 may determine that the TXOP obtained by STA 1602 on the PCH will be truncated (e.g., truncation of the TXOP is at a future time, before an end of TXOP duration 1612). In an embodiment, based on receiving frame 1620, STA 1604 may switch from the NPCA PCH to the PCH. In an embodiment, STA 1604 may switch from the NPCA PCH to the PCH after finishing any ongoing communication on the NPCA PCH.

[0145] In an embodiment, where STA 1604 comprises an AP STA, before switching to the PCH, STA 1604 may transmit, via the NPCA PCH, a frame 1622 announcing / indicating switching, by STA 1604, from the NPCA PCH to the PCH. In an embodiment, STA 1604 may perform a clear channel assessment (CCA) before transmitting frame 1622 and may transmit frame 1622 based on the NPCA PCH being idle. In an embodiment, frame 1622 may comprise a management frame, an action frame, a control frame, a quality of service (QoS) null frame, or a QoS data frame. In an embodiment, frame 1622 may comprise a broadcast frame. As such, STAs associated with STA 1604 and that are operating on the NPCA PCH may switch from the NPCA PCH to the PCH. In another embodiment, frame 1622 may comprise a frame addressed to another STA (not shown in FIG. 16), where the other STA is associated with STA 1604. As such, only the STA to which frame 1622 isDocket No.: 24-3052PCT addressed may switch from the NPCA PCH to the PCH. After transmitting frame 1622, STA 1604 may switch from the NPCA PCH to the PCH.

[0146] In another embodiment, where STA 1604 comprises a non-AP STA, STA 1604 may not announce the switching of STA 1604 from the NPCA PCH to the PCH and may only switch from the NPCA PCH to the PCH, based on receiving frame 1620.

[0147] In example 1600, STA 1604 switches from the NPCA PCH to the PCH before the transmitting of frame 1624.

[0148] After frame exchange 1618 on the PCH ends before the end of TXOP duration 1612, in accordance with existing IEEE 802.11 operation, STA 1602 may transmit frame 1624 to truncate the TXOP obtained by STA 1602 on the PCH. In an embodiment, frame 1624 may be a contention free-end (CF-end) frame. STA 1602 may transmit frame 1624 at a time T3, ending / truncating the TXOP on the PCH, as illustrated in example 1600, where time T3 is before the end of TXOP duration 1612 (e.g., before time T2). With the TXOP truncated, the PCH becomes available for contention by any STA operating on the PCH.

[0149] On receiving frame 1624, STA 1606 may reset NAV 1616 at time T3, earlier than the end of the OBSS NAV duration. In an embodiment, STA 1606 may be a UHR STA. In an embodiment, being a non-AP STA, STA 1606 may be configured to perform only triggered uplink transmission on the PCH after resetting NAV 1616 at time T3. In another embodiment, after resetting NAV 1616 at time T3, STA 1606 may be configured to wait until an end of TXOP duration 1612 to contend for the channel (despite that the TXOP associated with TXOP duration 1312 has been reset). This embodiment assumes that the UHR AP with which (UHR) STA 1606 is associated may still be operating / communicating on the NPCA PCH until the end of TXOP duration 1612. In another embodiment, STA 1606 may be a non-UHR STA. As such, after resetting NAV 1616 at time T3, STA 1606 may contend for the PCH if STA 1606 has buffered traffic (not shown in FIG. 16). Otherwise, if STA 1606 does not have buffered traffic, STA 1606 may not contend for the PCH.

[0150] On receiving frame 1624 via the PCH, STA 1604 may reset NAV 1614 on the PCH at time T3, before the end of TXOP duration 1612. After resetting NAV 1614 on the PCH, STA 1604 may perform a CCA before transmitting frame 1626 via the PCH and may transmit frame 1626 based on the PCH being idle. As such, by being informed by STA 1602 of an upcoming / future truncation of the TXOP on the PCH and switching from the NPCA PCH to the PCH, STA 1604 may communicate with its associated STAs (e.g., STA 1606) via the PCH, after the truncation of the TXOP obtained by STA 1602 on the PCH.

[0151] FIG. 17 shows another example 1700 that illustrates an example NPCA operation according to an embodiment. As shown in FIG. 17, example 1700 includes STAs 1702, 1704 and 1706. STAs 1704 and 1706 may belong to the same BSS. STA 1702 may belong to a different BSS than STAs 1704 and 1706. Each of STAs 1702, 1704 and 1706 may be an AP STA or a non-AP STA. In an embodiment, STA 1702 may be an AP STA, STA 1704 may be an AP STA, and STA 1706 may be a non-AP STA, or vice versa. In an embodiment, where STA 1704 is an AP STA and STA 1706 is a non-AP STA, STA 1706 may be associatedDocket No.: 24-3052PCT with STA 1704. In an embodiment, STAs 1702 and 1704 may support NPCA operation and may operate over a plurality of channels, including a primary channel (PCH), an NPCA primary channel (NPCA PCH), a first secondary channel (SCH1), a second secondary channel (SCH2), and a reserved channel. In an embodiment, the reserved channel may comprise a backhaul channel. In another embodiment, the reserved channel may comprise a control channel. In an embodiment, STA 1706 may not support NPCA operation and may operate only over the PCH. In an embodiment, where STA 1706 does not support NPCA operation, STA 1706 may be a non-ultra-high reliability (non-UHR) STA, such as an extremely high throughput (EHT) STA, a high efficiency (HE) STA, a very high throughput (VHT) STA, or a high throughput (HT) STA. In another embodiment, STA 1706 support NPCA operation but may have disabled / deactivated NPCA operation and may thus operate only over the PCH. In such an embodiment, STA 1706 may be a UHR STA.

[0152] As shown in FIG. 17, example 1700 may begin with STA 1702 transmitting a frame 1710 on the PCH. By transmitting frame 1710, STA 1702 may initiate and / or obtain a TXOP on the PCH Frame 1710 may be comprised in a PPDU comprising a TXOP duration field. The TXOP duration field may indicate a TXOP duration 1712. TXOP duration 1712 may indicate a duration that starts by the end of frame 1710 (e.g., starting at a time T1), and that ends at a time T2 as shown in FIG. 17.

[0153] In an embodiment, on receiving frame 1710, STA 1704 may determine that frame 1710 is comprised in an inter-BSS PPDU (OBSS PPDU). As discussed above in relation to FIG. 11 and in accordance with NPCA operation, STA 1704 may set a NAV 1714 for the PCH based on TXOP duration 1712 and may switch to the NPCA PCH for TXOP duration 1712 (OBSS NAV duration for STA 1704). In example 1700, STA 1704 may switch to the NPCA PCH at a time T1 . After switching to the NPCA PCH, STA 1704 may start a “MediumSyncDelay” timer for the medium synchronization duration of the NPCA PCH, and if the NPCA PCH is idle (at / after expiration of the MediumSyncDelay timer), STA 1704 may access the NPCA PCH to transmit a frame on the NPCA PCH (not shown in FIG. 17). In an example, STA 1704 may perform uplink and / or downlink communications via the NPCA PCH as illustrated by frame exchange 1715 in example 1700. In an example, frame exchange 1715 may end before an end of TXOP duration 1712. In an example, where STA 1704 is an AP STA, STA 1704 may communicate with its associated STAs via the NPCA PCH during TXOP duration 1712 and may be configured to switch back to the PCH by the end of TXOP duration 1712.

[0154] In an embodiment, on receiving frame 1710, STA 1706 may determine that frame 1710 is comprised in an inter-BSS PPDU (OBSS PPDU). Based on not supporting / enabling NPCA operation, STA 1706 may set a NAV 1716 for the PCH based on TXOP duration 1712 but may not switch to the NPCA PCH. Instead, STA 1706 remains on the PCH and remains silent until an end of TXOP duration 1712 (e.g., T2).

[0155] After transmitting frame 1710, STA 1702 may communicate with its associated STAs via the PCH within TXOP duration 1712. In an example, STA 1702 may perform uplink and / or downlink communications as illustrated with a frame exchange 1718. In an example (not shown in FIG. 17), frame exchange 1718 may extend to the end of TXOP duration 1712. In another example, as illustrated in example 1700, STA 1702 andDocket No.: 24-3052PCT its associated STAs may finish communicating before the end of TXOP duration 1712, and frame exchange 1718 may end before the end of TXOP duration 1712. In an embodiment, STA 1702 may be configured to transmit a frame indicating / informing truncation of the TXOP obtained by STA 1702 on the PCH, before transmitting a frame to truncate the TXOP on the PCH. In an embodiment, before transmitting a frame to truncate TXOP on the PCH, STA 1702 may transmit, via the reserved channel, a frame 1720 indicating / informing truncation of the TXOP on the PCH. In an embodiment, the reserved channel may comprise a backhaul channel . In another embodiment, the reserved channel may comprise a control channel. In an embodiment, frame 1720 may indicate a transmission time of the frame to truncate TXOP on the PCH (e.g ., transmission time of a frame 1724). In an embodiment, the transmitting of frame 1720 may be during frame exchange 1718. In an embodiment, the transmitting of frame 1720 is before the end of TXOP duration 1712.

[0156] In an embodiment, STA 1702 may perform a clear channel assessment (CCA) before transmitting frame 1720. In an embodiment, the CCA may use a first backoff counter value smaller than a second backoff counter used by another STA (not shown in FIG. 17). In an embodiment, the other STA may be a member of a BSS of STA 1702. In another embodiment, the other STA may be a member of an OBSS. In example 1700, STA 1702 transmits frame 1720 after determining that the reserved channel is idle. In an embodiment, frame 1720 may comprise a management frame, an action frame, a control frame, a quality of service (QoS) null frame, or a QoS data frame.

[0157] In an embodiment, STA 1702 may transmit frame 1720 addressed to STA 1704, where STA 1704 operates / camps on the NPCA PCH, during the TXOP on the PCH. In addition, STA 1704 also operates on the reserved channel For example, both STA 1702 and STA 1704 may comprise an AP STA, and STA 1702 may address frame 1720 to STA 1704 only to inform STA 1704 of the truncation of the TXOP on PCH.

[0158] On receiving frame 1720, STA 1704 may determine that the TXOP obtained by STA 1702 on the PCH will be truncated (e.g., truncation of the TXOP is at a future time, before an end of TXOP duration 1712). In an embodiment, based on receiving frame 1720, STA 1704 may switch from the NPCA PCH to the PCH. In an embodiment, STA 1704 may switch from the NPCA PCH to the PCH after finishing any ongoing communication on the NPCA PCH.

[0159] In an embodiment, where STA 1704 comprises an AP STA, before switching to the PCH, STA 1704 may transmit, via the NPCA PCH, a frame 1722 announcing / indicating switching, by STA 1704, from the NPCA PCH to the PCH. In an embodiment, STA 1704 may perform a clear channel assessment (CCA) before transmitting frame 1722 and may transmit frame 1722 based on the NPCA PCH being idle. In an embodiment, frame 1722 may comprise a management frame, an action frame, a control frame, a quality of service (QoS) null frame, or a QoS data frame. In an embodiment, frame 1722 may comprise a broadcast frame. As such, STAs associated with STA 1704 and that are operating on the NPCA PCH may switch from the NPCA PCH to the PCH. In another embodiment, frame 1722 may comprise a frame addressed to another STA (not shownDocket No.: 24-3052PCT in FIG. 17), where the other STA is associated with STA 1704. As such, only the STA to which frame 1722 is addressed may switch from the NPCA PCH to the PCH. After transmitting frame 1722, STA 1704 may switch from the NPCA PCH to the PCH.

[0160] In example 1700, STA 1704 switches from the NPCA PCH to the PCH before the transmitting of frame 1724.

[0161] After frame exchange 1718 on the PCH ends before the end of TXOP duration 1712, in accordance with existing IEEE 802.11 operation, STA 1702 may transmit frame 1724 to truncate the TXOP obtained by STA 1702 on the PCH. In an embodiment, frame 1724 may be a contention free-end (CF-end) frame. In example 1700, STA 1702 may transmit frame 1724 at a time T3, ending / truncating the TXOP on the PCH, as illustrated in example 1700, where time T3 is before the end of TXOP duration 1712 (e.g., before time T2). With the TXOP truncated, the PCH becomes available for contention by any STA operating on the PCH.

[0162] On receiving frame 1724, STA 1706 may reset NAV 1716 at time T3, earlier than the end of the OBSS NAV duration. In an embodiment, STA 1706 may be a UHR STA. In an embodiment, being a non-AP STA, STA 1706 may be configured to perform only triggered uplink transmission on the PCH after resetting NAV 1716 at time T3. In another embodiment, after resetting NAV 1716 at time T3, STA 1706 may be configured to wait until an end of TXOP duration 1712 to contend for the channel (despite that the TXOP associated with TXOP duration 1712 has been reset). This embodiment assumes that the UHR AP with which (UHR) STA 1706 is associated may still be operating / communicating on the NPCA PCH until the end of TXOP duration 1712. In another embodiment, STA 1706 may be a non-UHR STA. As such, after resetting NAV 1716 at time T3, STA 1706 may contend for the PCH if STA 1706 has buffered traffic (not shown in FIG. 17). Otherwise, if STA 1706 does not have buffered traffic, STA 1706 may not contend for the PCH.

[0163] On receiving frame 1724 via the PCH, STA 1704 may reset NAV 1714 on the PCH at time T3, before the end of TXOP duration 1712. After resetting NAV 1714 on the PCH, STA 1704 may perform a CCA before transmitting frame 1726 via the PCH and may transmit frame 1726 based on the PCH being idle. As such, by being informed by STA 1702 of an upcoming / future truncation of the TXOP on the PCH and switching from the NPCA PCH to the PCH, STA 1704 may communicate with its associated STAs (e.g., STA 1706) via the PCH, after the truncation of the TXOP obtained by STA 1702 on the PCH.

[0164] FIG. 18 shows another example 1800 that illustrates an example NPCA operation according to an embodiment. As shown in FIG. 18, example 1800 includes APs 1802 and 1804, and STAs 1806 and 1808. AP 1804, STA 1806 and STA 1808 may belong to the same BSS. AP 1802 may belong to a different BSS than AP 1804, STA 1806 and STA 1808. In an embodiment, STAs 1806 and 1808 may be associated with AP 1804. In an embodiment, APs 1802 and 1804, and STA 1808 may support NPCA operation and may operate over a plurality of channels, including a primary channel (PCH), an NPCA primary channel (NPCA PCH), a first secondary channel (SCH1 ), and a second secondary channel (SCH2). In an embodiment, STA 1806 may not support NPCA operation and may operate only over the PCH. In an embodiment, where STADocket No.: 24-3052PCT1806 does not support NPCA operation, STA 1806 may be a non-ultra-high reliability (non-UHR) STA, such as an extremely high throughput (EHT) STA, a high efficiency (HE) STA, a very high throughput (VHT) STA, or a high throughput (HT) STA. In another embodiment, STA 1806 may support NPCA operation but may have disabled / deactivated NPCA operation and may thus operate only over the PCH. In such an embodiment, STA 1806 may be a UHR STA.

[0165] As shown in FIG. 18, example 1800 may begin with AP 1804 transmitting a frame 1810 to AP 1802 on the PCH. In an embodiment, frame 1810 may indicate that AP 1802 supports / activates / uses / enables an NPCA operation. In an embodiment, frame 1810 may further indicate that AP 1804 has one or more associated STAs that do not support / enable the NPCA operation. In an embodiment, the one or more STAs may comprise non-UHR STAs. In another embodiment, the one or more STAs may comprise UHR STAs. In an embodiment, one or more associated STAs include STA 1806. In an embodiment, frame 1810 may comprise a management frame, an action frame, a control frame, a quality of service (QoS) null frame, or a QoS data frame.

[0166] On receiving frame 1810, AP 1802 may determine whether or not to disable TXOP truncation before the end of a TXOP obtained by AP 1802. In an embodiment, based on determining to disable TXOP truncation, AP 1802 may transmit a frame 1812 to AP 1804 informing AP 1804 of disabling truncation, by AP 1802, of a TXOP obtained by AP 1802 before the end of the TXOP duration. In another embodiment, based on determining to disable TXOP truncation, AP 1802 may not transmit frame 1812. In another embodiment, based on determining not to disable TXOP truncation, AP 1802 may not transmit frame 1812. In a further embodiment, based on determining not to disable TXOP truncation, AP 1802 may transmit frame 1812 informing AP 1804 of not disabling truncation, by AP 1802, of a TXOP obtained by AP 1802 before the end of the TXOP duration. In another embodiment, without the exchange of frames 1810 and / or 1812 (not shown in FIG. 18), AP 1802 may determine to disable TXOP truncation. In an embodiment, AP 1802 may determine to disable TXOP truncation based on the existence of another UHR AP (e.g., AP 1804) that may be within the communication range of AP 1802. By disabling TXOP truncation, AP 1802 may prevent / reduce any channel access disadvantage AP 1804 may have / experience if AP 1804 is on the NPCA PCH when a TXOP truncation occurs on the PCH.

[0167] In an embodiment, AP 1802 may transmit a frame 1814 on the PCH . By transmitting frame 1814, AP 1802 may initiate and / or obtain a TXOP on the PCH. Frame 1814 may be comprised in a PPDU comprising a TXOP duration field. The TXOP duration field may indicate a TXOP duration 1816. TXOP duration 1816 may indicate a duration that starts by the end of frame 1814 (e.g., starting at a time T1 ), and that ends at a time T2 as shown in FIG. 18.

[0168] In an embodiment, on receiving frame 1814, AP 1804 may determine that frame 1814 is comprised in an inter-BSS PPDU (OBSS PPDU). As discussed above in relation to FIG. 11 and in accordance with NPCA operation, AP 1804 may set a NAV 1818 for the PCH based on TXOP duration 1816 and may switchDocket No.: 24-3052PCT to the NPCA PCH for TXOP duration 1816 (OBSS NAV duration for AP 1804). In example 1800, AP 1804 may switch to the NPCA PCH at a time T1. After switching to the NPCA PCH, AP 1804 may start a “MediumSyncDelay” timer for the medium synchronization duration of the NPCA PCH, and if the NPCA PCH is idle (at / after expiration of the MediumSyncDelay timer), AP 1804 may access the NPCA PCH to transmit a frame on the NPCA PCH (not shown in FIG. 18). In an example, AP 1804 may perform uplink and / or downlink communications via the NPCA PCH as illustrated by frame exchange 1819 in example 1800. In an example, frame exchange 1819 may end before an end of TXOP duration 1816. In an example, AP 1804 may communicate with its associated ST As via the NPCA PCH during TXOP duration 1816 and may be configured to switch back to the PCH by the end of TXOP duration 1816.

[0169] In an embodiment, on receiving frame 1814, STA 1806 may determine that frame 1814 is comprised in an inter-BSS PPDU (OBSS PPDU). Based on not supporting / enabling NPCA operation, STA 1806 may set a NAV 1820 for the PCH based on TXOP duration 1816 but may not switch to the NPCA PCH. Instead, STA 1806 remains on the PCH and remains silent until an end of TXOP duration 1816 (e.g., T2).

[0170] In an embodiment, on receiving frame 1814, STA 1808 may determine that frame 1814 is comprised in an inter-BSS PPDU (OBSS PPDU). Based on supporting / enabling NPCA operation, STA 1808 may set a NAV 1821 for the PCH based on TXOP duration 1816 and may switch to the NPCA PCH for TXOP duration 1816 (OBSS NAV duration for STA 1808). In example 1800, STA 1808 may switch to the NPCA PCH at a time T1. Being associated with AP 1804, STA 1808 may be involved in uplink and / or downlink communications with AP 1804 via the NPCA PCH as illustrated by frame exchange 1819 in example 1800. In an embodiment, STA 1808 may be configured to switch back to the PCH by the end of TXOP duration 1816.

[0171] After transmitting frame 1814, AP 1802 may communicate with its associated STAs on the PCH within TXOP duration 1816. In an example, AP 1802 may perform uplink and / or downlink communications as illustrated with a frame exchange 1822. In an example (not shown in FIG. 18), frame exchange 1822 may be of the same duration as TXOP duration 1816. In example 1800, AP 1802 and its associated STAs may finish communicating before an end of TXOP duration 1816, and therefore, frame exchange 1822 may end before the end of TXOP duration 1816. Based on AP 1804 supporting / activating / using / enabling the NPCA operation, AP 1802 may not terminate / truncate (disable truncation of) the TXOP before the end of TXOP duration 1816. As such, by the end of TXOP duration 1816 (e.g., time T2), AP 1804 may switch from the NPCA PCH to the PCH (by the end of NAV 1818). In an embodiment, AP 1804 may perform a CCA before transmitting frame 1824 and may transmit frame 1824 based on the PCH being idle. As such, disabling truncation of the TXOP before the end of TXOP duration 1816 by AP 1802, AP 1804 may start communicating with its associated STAs (e.g., STA 1808) on the PCH, after the end of the TXOP. In another embodiment (not shown in FIG. 18), where AP 1802 indicates that AP 1802 determined not to disable TXOP truncationDocket No.: 24-3052PCT(e.g., in frame 1812), AP 1804 may return to the PCH as soon as AP 1804 finishes communication on the NPCA PCH.

[0172] By the end of TXOP duration 1816 (e.g., time T2), STA 1808 may switch from the NPCA PCH to the PCH. In an embodiment, STA 1808 switches back to the PCH (e.g., BSS primary channel) when an NPCA_TIMER expires. In an embodiment, after switching to the NPCA PCH, STA 1808 may set NPCA_TIMER to the largest non-zero value of the variables NPCA_PPDU_REM_DUR, NPCA_PHY_TXOP_REM_DUR, and NPCA_CFRAME_TXOP_REM_DUR, minus the switch back delay that STA 1808 indicated in the most recently transmitted NPCA Operation Parameters field. In an embodiment, STA 1808 may store the current values of the variables QSRCfAC], CW[AC] and the backoff counter for each enhanced distributed channel access function (EDCAF) when STA 1808 switches to the NPCA PCH. In an embodiment, STA 1808 may initiate a countdown of the MAC variable NPCA_TIMER in units of 1 s. In an embodiment, switching to the PCH may occur before the end of TXOP duration 1816 (not shown in FIG. 18), based on receiving a frame from AP 1802 on the NPCA PCH to return to the PCH. In an embodiment, the frame received from AP 1802 on the NPCA PCH to return to the PCH may be a trigger frame that has a value of zero in an NPCA primary channel indication subfield of a special user info field of the trigger frame. In another embodiment, returning to the PCH may occur before the end of the TXOP duration 1816 (not shown in FIG. 18), after a period of inactivity on the NPCA PCH. In an embodiment, a period of inactivity may comprise not receiving any frame from AP 1802 on the NPCA PCH for a predetermined duration. In another embodiment, returning to the PCH may occur before the end of TXOP duration 1816 (not shown in FIG. 18), based on not receiving a frame from AP 1802 addressed / intended to STA 1808. As such, STA 1808 may switch back to the PCH after a timeout interval. In another embodiment, returning to the PCH may occur before the end of TXOP duration 1816, based on STA 1808 receiving on the NPCA PCH an OBSS frame whose duration (e.g. PPDU duration, NAV duration) exceeds TXOP duration 1816 on the PCH (e.g., STA 1808 may switch back to the PCH immediately or within a time period after detecting the OBSS frame). In another embodiment, returning to the PCH may occur by / at the end of TXOP duration 1816, based on STA 1808 receiving on the NPCA PCH an OBSS frame whose duration (e.g. PPDU duration, NAV duration) is less than TXOP duration 1816 on the PCH. In an embodiment, where STA 1808 receives on the NPCA PCH an OBSS frame whose duration (e.g. PPDU duration, NAV duration) is less than TXOP duration 1816 on the PCH, STA 1808 and / or AP 1802 may switch back to the PCH immediately (or within a time period) after detecting the OBSS frame, based on determining that the remaining duration, after the OBSS NAV duration on the NPCA PCH, to be not enough to exchange frames on the NPCA PCH. In an embodiment, STA 1808 may be a non-AP STA. In another embodiment, STA 1808 may be an AP STA. In an embodiment, STA 1808 may be configured to perform only triggered uplink transmission on the PCH after switching from the NPCA PCH to the PCH. Thus, STA 1808 may not contend for the channel immediately after returning from the NPCA PCH to the PCH until a duration has elapsed. In an embodiment, the duration may be used to initializeDocket No.: 24-3052PCT a medium synchronization delay timer. While the medium synchronization delay timer has a non-zero value, STA 1808 may perform CCA until it receives a frame from AP 1804 (e.g. frame 1824 from AP 1804) on the PCH. In an embodiment, STA 1808 may initiate transmission on the PCH after receiving the frame from AP 1804 on the PCH (e.g. frame 1824) or after the medium synchronization delay timer has expired. In another embodiment, when STA 1808 switches back to the PCH, STA 1808 may replace the current values of the variables QSRC[AC], CW[AC], and the backoff counter for each EDCAF with the values that STA 1808 stored when it switched to the NPCA PCH, and may resume the backoff procedure.

[0173] FIG. 19 illustrates an example process 1900 according to an embodiment. Example process 1900 is provided for the purpose of illustration only and is not limiting of embodiments. Example process 1900 may be performed by a first station (STA), such as STA 1302, STA 1502, STA 1602, or STA 1702, for example. As shown in FIG. 19, example process 1900 may include steps 1902, and 1904.

[0174] Step 1902 includes transmitting, by the first STA and via a first channel, a first frame that truncates a transmission opportunity (TXOP) obtained by the first STA on the first channel.

[0175] Step 1904 includes transmitting, by the first STA and via a second channel, a second frame indicating / informing truncation of the TXOP on the first channel.

[0176] In an embodiment, the first channel comprises a primary channel (PCH). In an embodiment, the second channel comprises a non-primary channel access (NPCA) primary channel (PCH). In another embodiment, the second channel comprises an aggregate channel comprising the PCH and the NPCA PCH. In another embodiment, the second channel comprises a backhaul channel or a control channel.

[0177] In an embodiment, transmitting the second frame comprises transmitting the second frame to a second STA. In an embodiment, the second STA operates / camps on the second channel. In an embodiment, the first STA comprises a first access point (AP) STA and the second STA comprises a second AP STA. In another embodiment, the second frame comprises a broadcast frame.

[0178] In an embodiment, the transmitting of the second frame is after the transmitting of the first frame. In another embodiment, the transmitting of the second frame is before the transmitting of the first frame. In an embodiment, the second frame indicates a transmission time of the first frame.

[0179] In an embodiment, process 1900 may further comprise performing, by the first STA, a clear channel assessment (CCA) before transmitting the second frame. In an embodiment, the CCA uses a first backoff counter value smaller than a second backoff counter used by a third STA. In an embodiment, the transmitting of the second frame is based on the second channel being idle.

[0180] In an embodiment, the first frame comprises a contention free-end (CF-end) frame. In an embodiment, the second frame comprises a management frame, an action frame, a control frame, a quality of service (QoS) null frame, or a QoS data frame.Docket No.: 24-3052PCT

[0181] In an embodiment, process 1900 may further comprise transmitting, by the first STA, a third frame that initiates the TXOP on the first channel. In an embodiment, the third frame comprises a management frame, an action frame, a control frame, a quality of service (QoS) null frame, or a QoS data frame

[0182] In an embodiment, the first STA comprises an AP STA or a non-AP STA. In an embodiment, the second STA comprises an AP STA or a non-AP STA.

[0183] FIG. 20 illustrates another example process 2000 according to an embodiment. Example process 2000 is provided for the purpose of illustration only and is not limiting of embodiments. Example process 2000 may be performed by a first station (STA), such as STA 1304, STA 1504, STA 1604, or STA 1704, for example. As shown in FIG. 20, example process 2000 may include steps 2002 and 2004.

[0184] Step 2002 includes receiving, by the first STA from a second STA and via a first channel, a first frame indicating / informing truncation of a transmission opportunity (TXOP) obtained by the second STA on a second channel.

[0185] Step 2004 includes, based on receiving the first frame, switching, by the first STA, from a third channel to the second channel.

[0186] In an embodiment, process 2000 may further comprise transmitting, by the first STA and via the third channel, a second frame announcing / indicating switching, by the first STA, from the third channel to the second channel. In an embodiment, the first STA comprises an access point (AP) STA.

[0187] In an embodiment, the first channel comprises a non-primary channel access (NPCA) primary channel (PCH). In another embodiment, the first channel comprises an aggregate channel comprising a primary channel (PCH) and the NPCA PCH. In another embodiment, the first channel comprises a backhaul channel or a control channel. In an embodiment, the second channel comprises a primary channel (PCH) In an embodiment, the third channel comprises a non-primary channel access (NPCA) primary channel (PCH).

[0188] In an embodiment, the first frame comprises a broadcast frame. In another embodiment, the first frame comprises a frame addressed to the first STA. In an embodiment, the first frame indicates that the truncation of the TXOP is completed. In an embodiment, process 2000 may further comprise resetting, by the first STA, a basic network allocation vector (NAV) for the second channel, based on receiving the first frame.

[0189] In another embodiment, the first frame indicates a truncation time of the TXOP. In an embodiment, process 2000 may further comprise receiving, by the first STA from the second STA and via the second channel, a third frame, and resetting, by the first STA, a basic network allocation vector (NAV) for the second channel based on receiving the third frame. In an embodiment, the third frame comprises a contention free- end (CF-end) frame.

[0190] In an embodiment, process 2000 may further comprise receiving, by the first STA and via the second channel, a fourth frame setting the basic NAV for the second channel. In an embodiment, the basic NAV for the second channel is set to a duration of a TXOP obtained by the second STA on the second channel.Docket No.: 24-3052PCT

[0191] In an embodiment, the second frame comprises a broadcast frame. In another embodiment, the second frame comprises a frame addressed to a third STA. In an embodiment, the third STA is associated with the first STA.

[0192] In an embodiment, process 2000 may further comprise performing, by the first STA, a clear channel assessment (CCA) before transmitting the second frame. In an embodiment, the transmitting of the second frame is based on the third channel being idle.

[0193] In an embodiment, the first frame comprises a management frame, an action frame, a control frame, a quality of service (QoS) null frame, or a QoS data frame. In an embodiment, the second frame comprises a management frame, an action frame, a control frame, a quality of service (QoS) null frame, or a QoS data frame. In an embodiment, the fourth frame comprises a management frame, an action frame, a control frame, a quality of service (QoS) null frame, or a QoS data frame.

[0194] In an embodiment, the first STA comprises an AP STA or a non-AP STA. In an embodiment, the second STA comprises an AP STA or a non-AP STA.

[0195] FIG. 21 illustrates another example process 2100 according to an embodiment. Example process 2100 is provided for the purpose of illustration only and is not limiting of embodiments. Example process 2100 may be performed by a first access point (STA), such as AP 1802, for example. As shown in FIG. 21 , example process 2100 may include steps 2102, 2104, and 2106.

[0196] Step 2102 includes receiving, by the first AP from a second AP, a first frame indicating that the second AP supports / activates / uses / enables a non-primary channel access (NPCA) operation.

[0197] Step 2104 includes obtaining, by the first AP, a transmission opportunity (TXOP) on a primary channel (PCH).

[0198] Step 2106 includes, based on the second AP supporting / activating / using / enabling the NPCA operation, not terminating / truncating (disabling truncation of), by the first AP, the TXOP before an end of a duration of the TXOP.

[0199] In an embodiment, the first frame further indicates that the second AP has one or more associated stations (STAs) that do not support / enable the NPCA operation. In an embodiment, the one or more STAs comprise non-ultra-high reliability (non-UHR) STAs, and wherein non-UHR STAs comprise extremely high throughput (EHT) (EHT) STAs, high efficiency (HE) STAs, very high throughput (VHT) STAs, and high throughput (HT) STAs. In another embodiment, the one or more STAs comprise UHR STAs.

[0200] In an embodiment, process 2100 may further comprise transmitting, by the first AP to the second AP, a second frame informing the second AP of disabling truncation, by the first AP, of the TXOP before the end of the duration of the TXOP.

[0201] In an embodiment, the first frame comprises a management frame, an action frame, a control frame, a quality of service (QoS) null frame, or a QoS data frame. In an embodiment, the second frame comprisesDocket No.: 24-3052PCT a management frame, an action frame, a control frame, a quality of service (QoS) null frame, or a QoS data frame.

[0202] FIG. 22 illustrates another example process 2200 according to an embodiment. Example process 2200 is provided for the purpose of illustration only and is not limiting of embodiments. Example process 2200 may be performed by a first access point (STA), such as AP 1804, for example. As shown in FIG. 22, example process 2200 may include steps 2202, and 2204.

[0203] Step 2202 includes transmitting, by a first access point (AP) to a second AP, a first frame indicating that the first AP supports / activates / uses / enables a non-primary channel access (NPCA) operation.

[0204] Step 2204 includes receiving, by the first AP from the second AP, a second frame informing the first AP of disabling truncation, by the second AP, of a transmission opportunity (TXOP) on a primary channel (PCH), before an end of a duration of the TXOP.

[0205] In an embodiment, the first frame further indicates that the first AP has one or more associated stations (STAs) that do not support / enable the NPCA operation. In an embodiment, the one or more STAs comprise non-ultra high reliability (non-UHR) STAs, and wherein non-UHR STAs comprise extremely high throughput (EHT) (EHT) STAs, high efficiency (HE) STAs, very high throughput (VHT) STAs, and high throughput (HT) STAs. In another embodiment, the one or more STAs comprise UHR STAs.

[0206] In an embodiment, the first frame comprises a management frame, an action frame, a control frame, a quality of service (QoS) null frame, or a QoS data frame. In an embodiment, the second frame comprises a management frame, an action frame, a control frame, a quality of service (QoS) null frame, or a QoS data frame.

Claims

Docket No.: 24-3052PCTCLAIMSWhat is claimed is:1 . A method, comprising: transmitting, by a first access point (AP) and via a primary channel (PCH), a first frame that initiates a transmission opportunity (TXOP) on the PCH; before an end of the TXOP, transmitting, by the first AP and via the PCH, a second frame that truncates the TXOP; and based on transmitting the second frame, transmitting, by the first AP to a second AP, a third frame indicating truncation of the TXOP, wherein the second AP operates on a non-primary channel access (NPCA) PCH during the TXOP.

2. A method, comprising: transmitting, by a first station (STA) and via a first channel, a first frame that truncates a transmission opportunity (TXOP) obtained by the first STA on the first channel; and transmitting, by the first STA and via a second channel, a second frame indicating truncation of the TXOP on the first channel.

3. The method of claim 2, wherein the first channel comprises a primary channel (PCH).

4. The method of any of claims 2-3, wherein the second channel comprises a non-primary channel access (NPCA) primary channel (PCH).

5. The method of claim 4, wherein the second channel comprises an aggregate channel comprising the PCH and the NPCA PCH.

6. The method of any of claims 2-3, wherein the second channel comprises a backhaul channel or a control channel.

7. The method of any of claims 2-6, wherein transmitting the second frame comprises transmitting the second frame to a second STA.

8. The method of claim 7, wherein the second STA operates on the second channel.

9. The method of claim 7, wherein the first STA comprises a first access point (AP) STA and the secondSTA comprises a second AP STA.

10. The method of any of claims 2-6, wherein the second frame comprises a broadcast frame.1 1 . The method of any of claims 2-10, wherein the transmitting of the second frame is after the transmitting of the first frame.

12. The method of any of claims 2-10, wherein the transmitting of the second frame is before the transmitting of the first frame.

13. The method of claim 12, wherein the second frame indicates a transmission time of the first frame.

14. The method of any of claims 1 1 -13, further comprising performing, by the first STA, a clear channel assessment (CCA) before transmitting the second frame.Docket No.: 24-3052PCT15. The method of claim 14, wherein the CCA uses a first backoff counter value smaller than a second backoff counter used by a third STA.

16. The method of any of claims 14-15, wherein the transmitting of the second frame is based on the second channel being idle.

17. The method of any of claims 2-16, wherein the first frame comprises a contention free-end (CF-end) frame.

18. The method of any of claims 2-16, wherein the second frame comprises a management frame, an action frame, a control frame, a quality of service (QoS) null frame, or a QoS data frame.

19. The method of any claims 2-18, further comprising transmitting, by the first STA, a third frame that initiates the TXOP on the first channel.

20. The method of any of claims 2-8 and 10-19, wherein the first STA comprises an AP STA or a non-AP STA.21 . The method of any of claims 7-9, wherein the second STA comprises an AP STA or a non-AP STA.

22. A method, comprising: receiving, by a first access point (AP) and via a non-primary channel access (NPCA) primary channel (PCH), a first frame indicating truncation by a second AP of a transmission opportunity (TXOP) obtained by the second AP on a PCH; based on receiving the first frame, transmitting, by the first AP and via the NPCA PCH, a second frame indicating switching by the first AP from the NPCA PCH to the PCH; and switching, by the first AP, from the NPCA PCH to the PCH.

23. A method, comprising: receiving, by a first station (STA) from a second STA and via a first channel, a first frame indicating truncation of a transmission opportunity (TXOP) obtained by the second STA on a second channel; and based on receiving the first frame, switching, by the first STA, from a third channel to the second channel.

24. The method of claim 23, further comprising transmitting, by the first STA and via the third channel, a second frame indicating switching, by the first STA, from the third channel to the second channel.

25. The method of claim 24, wherein the first STA comprises an access point (AP) STA.

26. The method of any of claims 23-25, wherein the first channel comprises a non-primary channel access (NPCA) primary channel (PCH).

27. The method of claim 26, wherein the first channel comprises an aggregate channel comprising a primary channel (PCH) and the NPCA PCH.

28. The method of any of claims 23-25, wherein the first channel comprises a backhaul channel or a control channel.Docket No.: 24-3052PCT29. The method of any of claims 23-28, wherein the second channel comprises a primary channel (PCH).

30. The method of any of claims 23-29, wherein the third channel comprises a non-primary channel access (NPCA) primary channel (PCH).31 . The method of any of claims 23-30, wherein the first frame comprises a broadcast frame.

32. The method of any of claims 23-30, wherein the first frame comprises a frame addressed to the first STA.

33. The method of any of claims 31-32, wherein the first frame indicates that the truncation of the TXOP is completed.

34. The method of claim 33, further comprising resetting, by the first STA, a basic network allocation vector (NAV) for the second channel, based on receiving the first frame.

35. The method of any of claims 31-34, wherein the first frame indicates a truncation time of the TXOP.

36. The method of claim 35, further comprising: receiving, by the first STA from the second STA and via the second channel, a third frame; and resetting, by the first STA, a basic network allocation vector (NAV) for the second channel based on receiving the third frame.

37. The method of claim 36, wherein the third frame comprises a contention free-end (CF-end) frame.

38. The method of any of claims 34-37, further comprising receiving, by the first STA and via the second channel, a fourth frame setting the basic NAV for the second channel.

39. The method of claim 38, wherein the basic NAV for the second channel is set to a duration of a TXOP obtained by the second STA on the second channel.

40. The method of any of claims 24-39, wherein the second frame comprises a broadcast frame.41 . The method of any of claims 24-39, wherein the second frame comprises a frame addressed to a third STA.

42. The method of claim 41 , wherein the third STA is associated with the first STA.

43. The method of any of claims 24-42, further comprising performing, by the first STA, a clear channel assessment (CCA) before transmitting the second frame.

44. The method of claim 43, wherein the transmitting of the second frame is based on the third channel being idle.

45. The method of any of claims 23-44, wherein the first frame comprises a management frame, an action frame, a control frame, a quality of service (QoS) null frame, or a QoS data frame.

46. The method of any of claims 24-45, wherein the second frame comprises a management frame, an action frame, a control frame, a quality of service (QoS) null frame, or a QoS data frame.

47. The method of any of claims 39-44, wherein the fourth frame comprises a management frame, an action frame, a control frame, a quality of service (QoS) null frame, or a QoS data frame.

48. The method of any of claims 23-47, wherein the first STA comprises an AP STA or a non-AP STA.Docket No.: 24-3052PCT49. The method of any of claims 23-48, wherein the second STA comprises an AP STA or a non-AP STA.

50. A method, comprising: receiving, by a first access point (AP) from a second AP, a first frame indicating that the second AP supports or enables a non-primary channel access (NPCA) operation; obtaining, by the first AP, a transmission opportunity (TXOP) on a primary channel (PCH); and based on the second AP supporting or enabling the NPCA operation, not truncating, by the first AP, the TXOP before an end of a duration of the TXOP.51 . The method of claim 50, wherein the first frame further indicates that the second AP has one or more associated stations (STAs) that do not support / enable the NPCA operation.

52. The method of claim 51 , wherein the one or more STAs comprise non-ultra-high reliability (non-UHR) STAs, and wherein non-UHR STAs comprise extremely high throughput (EHT) (EHT) STAs, high efficiency (HE) STAs, very high throughput (VHT) STAs, or high throughput (HT) STAs.

53. The method of any of claims 50-52, further comprising transmitting, by the first AP to the second AP, a second frame informing the second AP of disabling truncation of, by the first AP, the TXOP before the end of the duration of the TXOP.

54. The method of any of claims 50-53, wherein the first frame comprises a management frame, an action frame, a control frame, a quality of service (QoS) null frame, or a QoS data frame.

55. The method of any of claims 50-54, wherein the second frame comprises a management frame, an action frame, a control frame, a quality of service (QoS) null frame, or a QoS data frame.

56. A method, comprising: transmitting, by a first access point (AP) to a second AP, a first frame indicating that the first AP supports or enables a non-primary channel access (NPCA) operation; and receiving, by the first AP from the second AP, a second frame informing the first AP of disabling truncation of, by the second AP, a transmission opportunity (TXOP) on a primary channel (PCH), before an end of a duration of the TXOP.

57. The method of claim 56, wherein the first frame further indicates that the first AP has one or more associated stations (STAs) that do not support / enable the NPCA operation.

58. The method of claim 57, wherein the one or more STAs comprise non-ultra high reliability (non-UHR) STAs, and wherein non-UHR STAs comprise extremely high throughput (EHT) (EHT) STAs, high efficiency (HE) STAs, very high throughput (VHT) STAs, or high throughput (HT) STAs.

59. The method of any of claims 56-58, wherein the first frame comprises a management frame, an action frame, a control frame, a quality of service (QoS) null frame, or a QoS data frame.

60. The method of any of claims 56-59, wherein the second frame comprises a management frame, an action frame, a control frame, a quality of service (QoS) null frame, or a QoS data frame.

61. A device comprising:Docket No.: 24-3052PCT one or more processors; and memory storing instructions that, when executed by the one or more processors of the device, cause the device to perform a method according to any of claims 1-60.

62. A non-transitory computer-readable medium comprising instructions that, when executed by one or more processors of a device, cause the device to perform a method according to any of claims 1-60.

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