Non-primary channel access (NPCA) switching operation

Abstract

: Channel switching is a mechanism used to help cope with interference. To facilitate channel switching, there is provided a method which comprises detecting, by a first or second station (STA) and via a primary channel, an overlapping basic service set (OBSS) physical layer protocol data unit (PPDU). After detecting the OBSS PPDU, the method comprises switching, by first STA, from the primary channel to a non-primary channel access (NPCA) primary channel based on a first NPCA switching mode used by the first STA and transmitting, by the first STA to a second STA, which receives it, a first frame via a bandwidth comprising the NPCA primary channel, wherein a transmission time of the first frame is based on a second NPCA switching mode used by the second STA.

Description

[0001] NON-PRIMARY CHANNEL ACCESS (NPCA) SWITCHING OPERATION

[0002] FIELD

[0003] The present invention relates to wireless networks, including those conforming to the IEEE 802.11 standard

[0004] BACKGROUND

[0005] Many modem wireless networks are in areas where installations of networks are very dense. The consequence is that any given network will be frequently subject to interference from overlapping networks i.e. networks which are not connected to the network in question (“the network”). In many cases the overlapping network may be of the same type as the network but has no coordination arranged with the network. Therefore, its transmissions may interfere with communications of the network - for example, causing devices in the network to refrain from transmitting or dropping packets. In the case of IEEE 802.11 (“Wi-Fi”) networks, overlapping networks are called overlapping basic service sets (OBSS) networks. Such delays are highly undesirable, particularly where the network is handling traffic which needs low latency or high reliability of transmission time.

[0006] A possibility for dealing with interfering transmissions is for devices of the network to switch to other channels on which there is no interference.

[0007] SUMMARY

[0008] Embodiments are defined by the appended independent claims. Further variants are provided by the appended dependent claims.

[0009] There are mechanisms of switching to other channels, in the case of Wi-Fi to a nonprimary channel. For example, an AP and a STA may operate on a primary channel (PCH) and a non-primary channel access primary channel (NPCA PCH) and may be arranged to switch when they detect and OBSS transmission.

[0010] To facilitate channel switching, there is provided a method which comprises detecting, by a first station (STA) and via a primary channel, an overlapping basic service set (OBSS) physical layer protocol data unit (PPDU). After detecting the OBSS PPDU, the method comprises switching, by first STA, from the primary channel to a non-primary channel access (NPCA) primary channel based on a first NPCA switching mode used by the first STA and transmitting, by the first STA to a second STA, a first frame via a bandwidth comprising the NPCA primary channel, wherein a transmission time of the first frame is based on a second NPCA switching mode used by the second STA.

[0011] Also, the method may comprise detecting, by a first station (STA) and via a primary channel, an overlapping basic service set (OBSS) physical layer protocol data unit (PPDU). Then, after detecting the OBSS PPDU, the first STA may switch, from the primary channel to a non-primary channel access (NPCA) primary channel based on a first NPCA switching mode used by the first STA and receiving, from a second STA, a first frame via a bandwidth comprising the NPCA primary channel, wherein a transmission time of the first frame is based on the first NPCA switching mode.

[0012] In the case of an access point (AP), the method may comprise receiving, from a first station (STA), a first frame indicating a first non-primary channel access (NPCA) switching mode used by the first STA, wherein the first NPCA switching mode indicates a first time at which the first STA switches from a primary channel to an NPCA primary channel after detecting a first overlapping basic service set (OBSS) physical layer protocol data unit (PPDU). The AP may transmit to the first STA, a second frame indicating a second NPCA switching mode used by the AP, wherein the second NPCA switching mode indicates a second time at which the AP switches from the primary channel to the NPCA primary channel after detecting a second OBSS PPDU. The AP may detect, via the primary channel, a third OBSS PPDU. After detecting the third OBSS PPDU, the AP may switch from the primary channel to the NPCA primary channel based on the second NPCA switching mode; and transmit, to the first STA, an initial control frame (ICF) via a bandwidth comprising the NPCA primary channel, wherein a transmission time of the ICF is based on the first NPCA switching mode.

[0013] In the case of a STA (a first STA) communicating with tan AP, the method may comprise transmitting, by to the AP, a first frame indicating a first non-primary channel access (NPCA) switching mode used by the first STA, wherein the first NPCA switching mode indicates a first time at which the first STA switches from a primary channel to an NPCA primary channel after detecting a first overlapping basic service set (OBSS) physical layer protocol data unit (PPDU). The STA may receive, from the AP, a second frame indicating a second NPCA switching mode used by the AP, wherein the second NPCA switching mode indicates a second time at which the AP switches from the primary channel to the NPCA primary channel after detecting a second OBSS PPDU. After detecting the third OBSS PPDU, the first STA may switch from the primary channel to the NPCA primary channel based on the first NPCA switching mode; and detecting, via the primary channel, a third OBSS PPDU. The first STA may receiving, an initial control frame (ICF) via a bandwidth comprising the NPCA primary channel, wherein a transmission time of the ICF is based on the first NPCA switching mode.

[0014] BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Examples of several of the various embodiments of the present disclosure are described herein with reference to the drawings.

[0016] FIG. 1 illustrates example wireless communication networks in which embodiments of the present disclosure may be implemented.

[0017] FIG. 2 is a block diagram illustrating example implementations of a station (STA) and an access point (AP).

[0018] FIG. 3 illustrates an example of a Medium Access Control (MAC) frame format.

[0019] FIG. 4 illustrates an example trigger frame.

[0020] FIG. 5 illustrates an example multi-user request to send (MU-RTS) trigger frame.

[0021] FIG. 6 illustrates an example of a common info field.

[0022] FIG. 7 illustrates an example of a Request-to-Send (RTS) / Clear-to-Send (CTS) procedure.

[0023] FIG. 8 is an example that illustrates an MU-RTS / CTS procedure.

[0024] FIG. 9 is an example that illustrates non-primary channel access (NPCA) operation.

[0025] FIG. 10 illustrates virtual and physical carrier sense (CS) functions associated with primary and secondary channels for NPCA operation and non-NPCA operation.

[0026] FIG. 11 shows an example that illustrates NPCA operation.

[0027] FIG. 12 illustrates an inefficiency that may arise in the NPCA operation of FIG. 11.

[0028] FIG. 13 illustrates a problem that may arise due to a mismatch of NPCA switching modes between STAs.

[0029] FIG. 14 shows an example that illustrates an example NPCA operation according to an embodiment. FIG. 15 shows another example that illustrates another example NPCA operation according to an embodiment.

[0030] FIG. 16 shows another example that illustrates another example NPCA operation according to an embodiment.

[0031] FIG. 17 shows another example that illustrates another example NPCA operation according to an embodiment.

[0032] FIG. 18 shows another example that illustrates another example NPCA operation according to an embodiment.

[0033] FIG. 19 shows another example that illustrates another example NPCA operation according to an embodiment.

[0034] FIG. 20 illustrates an example process according to an embodiment.

[0035] FIG. 21 illustrates another example process according to an embodiment.

[0036] FIG. 22 shows another example that illustrates another example NPCA operation according to an embodiment.

[0037] FIG. 23 shows another example that illustrates another example NPCA operation according to an embodiment.

[0038] DETAILED DESCRIPTION

[0039] 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. 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.

[0040] 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 a 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.

[0041] 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.

[0042] 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.

[0043] In this disclosure, parameters (or equally called, fields, or Information elements: IES) 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.

[0044] 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 disclosure 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.

[0045] 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.

[0046] FIG. 1 illustrates example wireless communication networks in which embodiments of the present disclosure may be implemented.

[0047] 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.

[0048] 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 110-2 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.

[0049] 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).

[0050] 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., 802. 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.

[0051] 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).

[0052] 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.

[0053] 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.

[0054] 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.

[0055] A frequency band may include one or more sub-bands or frequency channels. For example, PPDUs conforming to the IEEE 802.1 In, 802.1 lac, 802.1 lax and / or 802.1 Ibe 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 channel 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.

[0056] 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.

[0057] 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.

[0058] 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.

[0059] 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. 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.

[0060] As shown in FIG. 3, a MAC frame includes a MAC header, a variable length frame body, and a frame check sequence (FCS).

[0061] 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.

[0062] 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.

[0063] The protocol version subfield is invariant in size and placement across all revisions of the IEEE 802.11 standard. The value of the protocol version subfield is 0 for MAC frames.

[0064] 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.

[0065] 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.

[0066] 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.

[0067] 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.

[0068] The power management subfield is used to indicate the power management mode of a STA.

[0069] 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.

[0070] The protected frame subfield is set to 1 if the frame body field contains information that has been processed by a cryptographic encapsulation algorithm.

[0071] The +HTC subfield indicates that the MAC frame contains an HT control field.

[0072] 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 frames 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.

[0073] 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.

[0074] 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.

[0075] 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.

[0076] 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.

[0077] 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.

[0078] 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.

[0079] 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 lax 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.

[0080] 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.

[0081] 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.

[0082] 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).

[0083] 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.

[0084] 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.

[0085] 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.

[0086] 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 Is.

[0087] 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.

[0088] 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 a 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.

[0089] 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.

[0090] 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 GI 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 sub field, a PE Disambiguity subfield, an UL Spatial Reuse subfield, a third Reserved subfield, an HE / EHT Pl 60 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, GI 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 Pl 60 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 802.1 Ibe draft amendment (“IEEE P802.1 lbe / D3.1, March 2023”).

[0091] 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 802.11 standard draft “IEEE P802.1 l-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.

[0092] 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 SIFS (Short Interframe Spacing) periods.

[0093] 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-SIG 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 SIG 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.

[0094] 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.

[0095] 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.

[0096] 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. 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 802.11 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).

[0097] 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.

[0098] 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.

[0099] 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 SIFS periods.

[0100] 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. 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.

[0101] 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-AP STA 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.

[0102] 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 SIFS 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 802.11 standard (“IEEE P802.1 l-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. 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 SIFS period.

[0103] 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.

[0104] 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.

[0105] 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.

[0106] 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), 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.

[0107] 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).

[0108] 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.

[0109] 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 (nonzero 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”).

[0110] 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.

[0111] FIG. 11 shows an example 1100 that illustrates NPCA operation. As shown in FIG. 11, example 1100 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).

[0112] Example 1100 may begin with the AP transmitting a frame 1102 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 1102 may be a management frame, such as a beacon frame, for example.

[0113] 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 1104 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 1104 on the PCH. Frame 1104 may indicate a transmission on the PCH. A duration of the transmission on the PCH may be provided by a duration field of frame 1104, a transmission opportunity (TXOP) duration field of an OBSS PPDU comprising frame 1104, or a length field of the OBSS PPDU. The AP and STA may set their NAVs for the PCH based on the duration of the OBSS transmission on the PCH (OBSS NAV duration).

[0114] In accordance with NPCA operation, on receiving an OBSS 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. 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. 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 1102). In example 1100, 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 1106 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.

[0115] In basic NPCA operation, a STA (AP STA or non-AP STA) may be configured to switch to the NPCA PCH only when the STA is able to obtain the OBSS NAV duration from the OBSS PPDU. In some cases, however, the STA may fail to obtain the OBSS NAV duration from the OBSS PPDU. For example, a TXOP field of the OBSS PPDU (which indicates a TXOP duration associated with the OBSS PPDU) may be set to “UNSPECIFIED” and the STA may fail to decode MPDU(s) contained in the OBSS PPDU to obtain the TXOP duration. As illustrated in example 1200 of FIG. 12, this failure to obtain the OBSS NAV duration may result in a non-AP STA not switching to the NPCA PCH despite detecting the OBSS PPDU on the PCH. As such, the non-AP STA may remain on the PCH, while the AP STA switches to the ACH for the duration of the OBSS NAV. The non-AP STA may fail to receive frame 1106 transmitted by the AP STA and may be deprived from communication until the AP STA returns to the PCH at the end of the OBSS NAV duration.

[0116] To mitigate this potential problem, in an enhanced NPCA operation, a STA (AP STA or non-AP STA) may be configured to switch to the NPCA PCH on detecting an OBSS PPDU on the PCH even when the STA is unable to determine the OBSS NAV duration from the OBSS PPDU. With a non-AP STA switching to the NPCA PCH without having determined the OBSS NAV duration, the non-AP STA may not have knowledge of the time at which the AP STA will return to the PCH. In an implementation, after switching to the NPCA PCH, an AP STA may be configured to transmit on the NPCA PCH a frame that indicates a duration based on the OBSS NAV duration. The frame informs the non-AP STA of the time at which the non-AP STA should return to the PCH.

[0117] The time at which a STA (AP STA or non-AP STA) switches from the PCH to the NPCA PCH may be based on an NPCA switching mode used by the STA. Specifically, the NPCA switching mode used by the STA indicates a time at which the STA switches from the PCH to the NPCA PCH after receiving an OBSS PPDU on the PCH.

[0118] According to a first mode (hereinafter also referred to as Mode 1), the STA switches from the PCH to the NPCA PCH after receiving a signal field of a PPDU being received on the PCH and determining based on the signal field that the PPDU is an OBSS PPDU. In an implementation, the signal field may be comprised in a PHY portion (e.g., PHY header) of the PPDU. For example, the signal field may be a very high throughput (VHT)-SIG-A field of a VHT PPDU, a high efficiency (HE)-SIG-A field of an HE PPDU, or a universal signal (U-SIG) field of an extremely high throughput (EHT) PPDU or an ultra-high reliability (UHR) PPDU. In an implementation, the signal field comprises a BSS color field that allows the STA to determine whether the PPDU is an inter-BSS PPDU (OBSS PPDU) or an intra-BSS PPDU. In an implementation, the signal field comprises a partial AID field (e.g., in VHT-SIG-A) that allows the STA to determine whether the PPDU is an inter-BSS PPDU (OBSS PPDU) or an intra-BSS PPDU. In an implementation, the signal field comprises a group ID field (e.g., in VHT-SIG-A) that allows the STA to determine whether the PPDU is an inter-BSS PPDU (OBSS PPDU) or an intra-BSS PPDU or whether the PPDU is for a DL transmission, a UL transmission, or an SU / MU transmission. In an implementation, the signal field comprises a TXOP field that indicates a TXOP duration associated with the PPDU. After determining that the PPDU is an OBSS PPDU based on the BSS color field, the STA may be configured to determine the OBSS NAV duration based on the TXOP field of the signal field of the PPDU. According to this implementation, the STA may be configured to switch from the PCH to the NPCA PCH after reading the TXOP field of the signal field of the PPDU, regardless of whether the STA is able to determine the OBSS NAV duration based on the TXOP field. That is, after reading the TXOP field of the PPDU, the STA may stop processing / decoding the PPDU and may switch immediately to the NPCA PCH. In an implementation, when the STA does not determine the OBSS NAV before switching to the NPCA PCH, the STA may be configured to return to the PCH at or before the end of the OBSS PPDU.

[0119] According to a second mode (hereinafter also referred to as Mode 2), after determining that a PPDU being received on the PCH is an OBSS PPDU and failing to determine / obtain the OBSS NAV duration (e.g., based on the TXOP field of the signal field of the PPDU or based on the absence of a TXOP field in the signal field), the STA may continue to process the PPDU to read / decode one or more MPDU (indicating the TXOP duration associated with the PPDU) contained in the PPDU. In an implementation, the STA may be configured to switch from the PCH to the NPCA PCH after reading / decoding (or trying to read / decode) the one or more MPDU of the PPDU, regardless of whether the STA is able to determine the OBSS NAV duration based on the TXOP duration. That is, after reading / decoding (or trying to read / decode) the one or more MPDU of the PPDU, the STA may stop processing / decoding the PPDU and may switch immediately to the NPCA PCH. In an implementation, the STA may be configured to read / decode (or try to read / decode) a first occurring MPDU (or a fixed number of first occurring MPDUs) of the PPDU before switching to the NPCA PCH. In another implementation, the STA may be configured to read / decode (or try to read / decode) a delimiter of a first occurring MPDU PPDU before switching to the NPCA PCH. In an implementation, when the STA does not determine the OBSS NAV before switching to the NPCA PCH, the STA may be configured to return to the PCH at or before the end of the OBSS PPDU.

[0120] In implementation, STAs may support different NPCA switching modes and may activate / use different NPCA switching modes during NPCA operation. As a result, STAs may switch to the NPCA PCH at different times in response to the same OBSS PPDU detected on the PCH. This mismatch may cause a loss of frames between the STAs as illustrated in example 1300 of FIG. 13.

[0121] As shown in FIG. 13, example 1300 includes an AP and a STA associated with the AP. The AP and the STA may both support NPCA operation but may be using different NPCA switching modes. Specifically, the AP may be using the first mode (Mode 1) described above. That is, the AP may be configured to switch to the NPCA PCH after reading the signal field (or the TXOP field of the signal field) of the OBSS PPDU, regardless of whether the AP determines the OBSS NAV duration (e.g., based on the signal field). In contrast, the STA may be using the second NPCA switching mode (Mode 2) described above. That is, the STA may be configured to switch to the NPCA PCH only after reading / decoding a first occurring MPDU of the OBSS PPDU to try to determine the OBSS NAV duration based on a TXOP duration indicated in the first occurring MPDU.

[0122] In example 1300, it is assumed, for the purpose of illustration, that the TXOP field of the OBSS PPDU is set to “UNSPECIFIED.” On detecting the OBSS PPDU on the PCH, the AP may read the BSS color field of the signal field of the PPDU to determine that the PPDU is an inter-BSS PPDU (OBSS PPDU). The AP may then read the TXOP field of the signal field of the OBSS PPDU to determine the OBSS NAV duration. Based on using the first mode, the AP switches to the NPCA PCH after reading the TXOP field, regardless of whether the AP is able to determine the OBSS NAV duration from the TXOP field. Specifically, as shown in example 1300, the AP switches to the NPCA PCH, at a time tl, immediately after reading the TXOP field of the OBSS PPDU. As the TXOP field of the OBSS PPDU is set to “UNSPECIFIED” in example 1300, the AP switches to the NPCA PCH without knowledge of the OBSS NAV duration. Accordingly, in an implementation, the AP may return to the PCH at or before the end of OBSS PPDU

[0123] The STA may detect the OBSS PPDU on the PCH in parallel to the AP. On detecting the OBSS PPDU, the STA may read the BSS color field of the signal field of the PPDU to determine that the PPDU is an inter-BSS PPDU (OBSS PPDU). The STA may then read the TXOP field of the signal field of the OBSS PPDU to determine the OBSS NAV duration. Based on the TXOP field of the OBSS PPDU being set to “UNSPECIFIED” and the STA using the second NPCA switching mode, the STA may continue processing / reading the OBSS PPDU to read / decode the first occurring MPDU of the OBSS PPDU. After reading / decoding the first occurring MPDU, and regardless of whether the STA determines the OBSS NAV duration based on a TXOP duration indicated in the first occurring MPDU, the STA switches to the NPCA PCH. Specifically, as shown in example 1300, the STA switches to the NPCA PCH, at a time t2, immediately after reading / decoding the first occurring MPDU of the OBSS PPDU. It is assumed in example 1300, for the purpose of illustration, that the STA fails to determine the OBSS NAV duration from the first occurring MPDU (e.g., the STA fails to decode the first occurring MPDU) and therefore switches to the NPCA PCH without knowledge of the OBSS NAV duration. Accordingly, in an implementation, the STA may return to the PCH at or before the end of the OBSS PPDU (e.g., if the STA does not get the OBSS NAV duration of the OBSS PPDU on NPCA PCH). In another implementation, the STA may return to the PCH at or before the end of the OBSS NAV duration (e.g., if the STA does get the OBSS NAV duration of the OBSS PPDU on NPCA PCH).

[0124] As shown in FIG. 13, the mismatch between the NPCA PCH switching modes used by the AP and STA results in the AP switching to the NPCA PCH before the STA in example 1300. The AP may attempt to communicate with the STA on the NPCA PCH in between times tl and t2, for example by transmitting one or more initial control frame (ICF) to the STA on the NPCA PCH (or on a channel comprising the NPCA PCH). However, as the STA only switches to the NPCA PCH at time t2, the STA does not receive the one or more ICF from the AP before time t2. NPCA PCH resources, as well as AP resources, used to transmit the one or more ICF to the STA may be wasted. Embodiments of the present disclosure, as further described below, address the above-discussed problem of existing technologies. In an aspect, a first STA (e.g., AP STA) receives from a second STA (e.g., non-AP STA) a first frame indicating a first NPCA switching mode used by the second STA The first NPCA switching mode indicates a first time at which the second STA switches from a primary channel to an NPCA primary channel after detecting an OBSS PPDU on the primary channel. The first STA switches from the primary channel to the NPCA primary channel after detecting a first OBSS PPDU on the primary channel. The first STA may switch from the primary channel to the NPCA primary channel based on a second NPCA switching mode used by the first STA. The second NPCA switching mode indicates a second time at which the first STA switches from the primary channel to the NPCA primary channel after detecting an OBSS PPDU on the primary channel. After switching to the NPCA primary channel, the first STA transmits to the second STA a frame via the NPCA primary channel. In an embodiment, a transmission time of the frame is based on the first NPCA switching mode used by the second STA. This ensures that the first STA transmits the frame to the second STA after the second STA has switched to the NPCA primary channel. Loss of NPCA PCH resources (and first STA resources) by transmitting frames to the second STA before the second STA has switched to the NPCA PCH may thus be avoided.

[0125] In an embodiment, the first STA (e.g., AP STA) transmits to the second STA (e.g., non-AP STA) a second frame indicating a second NPCA switching mode used by the first STA regardless of the first frame (e.g., without receiving the first frame or after receiving the first frame). The second frame may comprise a beacon frame, a fast initial link setup (FILS) discovery frame, a short beacon frame, a traffic indication map (TIM) broadcast frame, a broadcast frame, or an announcement frame. In an embodiment, after receiving the second frame, based on the second NPCA switching mode, the second STA may use the second NPCA switching mode for the second STA to switch to the NPCA PCH. In another embodiment, after receiving the second frame, based on the second NPCA switching mode, the second STA may deactivate (disable) the NPCA switching operation. In another embodiment, after receiving the second frame, based on the second NPCA switching mode, the second STA may accept or reject the second NPCA switching mode.

[0126] In an embodiment, the first STA (the second STA) may switch to the NPCA primary channel based on a length of an OBSS PPDU received on the primary channel ( or based on a remaining duration of the OBSS PPDU). For example, if a remaining duration of OBSS PPDU exceeds an NPCA switching duration threshold (e.g., the remaining duration of the OBSS PPDU is sufficient for the first STA and the second STA to exchange frames on the NPCA PCH), the first STA and / or the second STA may switch to the NPCA PCH after receiving (detecting / decoding) a SIG field (e.g., VHT-SIG-A field, HE-SIG-A field, U-SIG field, etc.) of the OBSS PPDU without receiving (decoding / reading) the remaining parts (e.g., 1st MPDU, the MAC header of the 1stMPDU, or the MPDU delimiter of the 1stMPDU, etc.) of the OBSS PPDU. Otherwise (e.g., if the remaining duration of the OBSS PPDU is less than the NPCA switching duration threshold), the first STA and / or the second STA may not switch to the NPCA PCH after receiving the SIG field (e.g., VHT-SIG-A field, HE-SIG-A field, U-SIG field, etc.) and may continue to receive the remaining parts (e.g., one of 1st MPDU, the MAC header of the 1stMPDU, and the MPDU delimiter of the 1stMPDU) of the OBSS PPDU. In an embodiment, the NPCA switching duration threshold may comprise a time duration for the STA to switch to the NPCA PCH from the PCH and operate on the NPCA PCH.

[0127] In an embodiment, if a received OBSS (inter-BSS) PPDU is a high throughput (HT) PPDU, a STA (e.g., the first STA (AP), the second STA (non-AP STA)) may decide to switch to the NPCA PCH from the PCH based on a length of an MPDU (e.g., a first MPDU or MPDU 1) of the received OBSS PPDU. For example, if the length of the first MPDU of the received OBSS HT PPDU is greater than a threshold (e.g., the remaining duration of the received OBSS PPDU is less than the NPCA switching duration threshold), the STA may switch to the NPCA PCH from the PCH after either receiving one or more fields of a MAC header of the first MPDU of the received OBSS PPDU to determine that the received PPDU is an OBSS PPDU. In an example, the one or more fields may comprise one or more of a Frame Control field, a Duration / ID field, an Address 1, an Address 2, an Address 3, and an Address 4 of the MAC header of the first MPDU of the received OBSS PPDU.

[0128] FIG. 14 shows an example 1400 that illustrates an example NPCA operation according to an embodiment. Example 1400 is provided for the purpose of illustration only and is not limiting of embodiments. As shown in FIG. 14, example 1400 includes STAs 1402 and 1404. STAs 1402 and 1404 may belong to the same BSS. Each of STAs 1402 and 1404 may be an AP STA or a non-AP STA. In an embodiment, STA 1402 may be an AP STA, and STA 1404 may be a non- AP STA, or vice versa. In an embodiment, where STA 1402 is an AP STA and STA 1404 is a non-AP STA, STA 1404 may be associated with STA 1402. STAs 1402 and 1404 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). In an embodiment, each of STAs 1402 and 1404 may support one or more NPCA switching modes. The one or more NPCA switching modes may include the first mode (Mode 1) described above and the second mode (Mode 2) described above.

[0129] As shown in FIG. 14, example 1400 may begin with STA 1402 transmitting a frame 1406. Frame 1406 may indicate a first NPCA switching mode used / activated / enabled by STA 1402. In an embodiment, STA 1402 may be an AP STA, and frame 1406 may comprise a beacon frame, a fast initial link setup (FILS) discovery frame, a short beacon frame, a traffic indication map (TIM) broadcast frame, a broadcast frame, or an announcement frame, for example.

[0130] In an embodiment, frame 1406 may indicate one or more NPCA switching modes supported by STA 1402. In an implementation, frame 1406 may comprise a capability element that indicates the one or more NPCA switching modes supported by STA 1402. The first NPCA switching mode used / activated / enabled by STA 1402 may correspond to one of the one or more NPCA switching modes supported by STA 1402. In an example, the one or more NPCA switching modes supported by STA 1402 include the first mode (Mode 1) and / or the second mode (Mode 2) described above. In an embodiment, where STA 1402 supports more than one NPCA switching modes, STA 1402 may activate / enable more than one NPCA switching modes. STA 1402 may indicate the more than one NPCA switching modes in frame 1406. STA 1402 may use different NPCA switching modes of the more than one NPCA switching modes in different scenarios. For example, STA 1402 may support and activate / enable both the first mode (Mode 1) and the second mode (Mode 2). STA 1402 may use the first mode (Mode 1) when the OBSS PPDU comprises a VHT PPDU, an HE PPDU, an EHT PPDU, or a UHR PPDU, and may use the second mode (Mode 2) when the OBSS PPDU comprises an HT PPDU.

[0131] The first NPCA switching mode indicates a first time at which STA 1402 switches from the PCH to the NPCA PCH after detecting an OBSS PPDU on the PCH. In example 1400, the first NPCA switching mode used by STA 1402 corresponds to the first mode (Mode 1) described above. As mentioned above, according to the first mode, STA 1402 may be configured to switch from the PCH to the NPCA PCH after receiving / decoding a signal (SIG) field of a PPDU being received on the PCH and determining based on the SIG field that the PPDU is an OBSS PPDU. In an embodiment, where the PPDU being received on the PCH comprises an extremely high throughput (EHT) PPDU, an ultra-high reliability (UHR) PPDU, or a UHR+ PPDU, the SIG field comprises a universal SIG (U-SIG) field of the PPDU. In an embodiment, where the PPDU being received on the PCH comprises a high efficiency (HE) PPDU, the SIG field comprises an HE-SIG-A field of the PPDU. In an embodiment, where the PPDU being received on the PCH comprises a very high throughput (VHT) PPDU, the SIG field comprises a VHT-SIG-A field of the first OBSS PPDU. In an embodiment, STA 1402 may be configured to stop processing / decoding the PPDU being received on the PCH and to switch immediately to the NPCA PCH after reading the TXOP field of the SIG field of the PPDU. The first time indicated by the first NPCA switching mode may thus correspond to the time that STA 1402 finishes reading / decoding the TXOP field of the PPDU being received on the PCH. In another embodiment, STA 1402 may switch to the NPCA PCH after finishing reading / decoding the SIG field of the PPDU. The first time indicated by the first NPCA switching mode may thus correspond to the time that STA 1402 finishes reading / decoding the SIG field of the PPDU being received on the PCH.

[0132] Subsequently, example 1400 may include STA 1404 transmitting a frame 1408 to STA 1402. Frame 1408 may indicate a second NPCA switching mode used / activated / enabled by STA 1404. In an embodiment, frame 1408 comprises an operation mode field that indicates the second NPCA switching mode used / activated / enabled by STA 1404. Frame 1408 may comprise a probe request frame, an association request frame, a reassociation request frame, a request frame, a management frame, an action frame, a control frame, a quality of service (QoS) null frame, or a QoS data frame, for example. In an embodiment, where frame 1408 comprises a request frame, frame 1408 comprises a request from STA 1404 to STA 1402 to use the indicated second NPCA switching mode used / activated / enabled by STA 1404.

[0133] In an embodiment, frame 1408 may indicate one or more NPCA switching modes supported by STA 1404. In an implementation, frame 1408 may comprise a capability element that indicates the one or more NPCA switching modes supported by STA 1404. The second NPCA switching mode used / activated / enabled by STA 1404 may correspond to one of the one or more NPCA switching modes supported by STA 1404. In an example, the one or more NPCA switching modes supported by STA 1404 include the first mode (Mode 1) and / or the second mode (Mode 2) described above. In an embodiment, where STA 1404 supports more than one NPCA switching modes, STA 1404 may activate / enable more than one NPCA switching modes. STA 1404 may indicate the more than one NPCA switching modes in frame 1408. STA 1404 may use different NPCA switching modes of the more than one NPCA switching modes in different scenarios. For example, STA 1404 may support and activate / enable both the first mode (Mode 1) and the second mode (Mode 2). STA 1404 may use the first mode (Mode 1) when the OBSS PPDU comprises a VHT PPDU, an HE PPDU, an EHT PPDU, or a UHR PPDU, and may use the second mode (Mode 2) when the OBSS PPDU comprises an HT PPDU.

[0134] The second NPCA switching mode indicates a second time at which STA 1404 switches from the PCH to the NPCA PCH after detecting an OBSS PPDU on the PCH. In example 1400, the second NPCA switching mode used by STA 1404 corresponds to the first mode (Mode 1) described above. As mentioned above, according to the first mode, STA 1404 may be configured to switch from the PCH to the NPCA PCH after receiving / decoding a signal (SIG) field of a PPDU being received on the PCH and determining based on the SIG field that the PPDU is an OBSS PPDU. In an embodiment, where the PPDU being received on the PCH comprises an EHT PPDU, a UHR PPDU, or a UHR+ PPDU, the SIG field comprises a U-SIG field of the PPDU. In an embodiment, where the PPDU being received on the PCH comprises an HE PPDU, the SIG field comprises an HE-SIG-A field of the PPDU. In an embodiment, where the PPDU being received on the PCH comprises a VHT PPDU, the SIG field comprises a VHT-SIG-A field of the first OBSS PPDU. In an embodiment, STA 1404 may be configured to stop processing / decoding the PPDU being received on the PCH and to switch immediately to the NPCA PCH after reading the TXOP field of the SIG field of the PPDU. The second time indicated by the second NPCA switching mode may thus correspond to the time that STA 1404 finishes reading / decoding the TXOP field of the PPDU being received on the PCH. In another embodiment, STA 1404 may switch to the NPCA PCH after finishing reading / decoding the SIG field of the PPDU. The second time indicated by the second NPCA switching mode may thus correspond to the time that STA 1404 finishes reading / decoding the SIG field of the PPDU being received on the PCH.

[0135] In an embodiment, STA 1402 may respond to frame 1408 from STA 1404 by transmitting a frame 1410 to STA 1404. In another embodiment, STA 1402 may not respond to frame 1408 from STA 1404. In an embodiment, frame 1410 acknowledges frame 1410. In another embodiment, frame 1410 responds to frame 1410. In an embodiment, frame 1410 indicates the first NPCA switching mode used / activated / enabled by STA 1402. In an embodiment, frame 1410 comprises an operation mode field that indicates the first NPCA switching mode used / activated / enabled by STA 1402. Frame 1410 may comprise a probe response frame, an association response frame, a reassociation response frame, a response frame, a management frame, an action frame, a control frame, a quality of service (QoS) null frame, or a QoS data frame, for example. In an embodiment, where frame 1408 comprises a request frame as described above, frame 1410 may comprise a response frame that comprises a response to the request from STA 1404 to STA 1402 to use the indicated second NPCA switching mode used / activated / enabled by STA 1404. The response may accept or reject the request comprised in frame 1408. For example, if STA 1402 supports the second NPCA switching mode indicated in frame 1408, STA 1402 may accept the request comprised in frame 1408. Conversely, if STA 1402 does not support the second NPCA switching mode indicated in frame 1408, STA 1402 may reject the request comprised in frame 1408. In an embodiment, frame 1410 may indicate one or more NPCA switching modes supported by STA 1402. In an implementation, frame 1410 may comprise a capability element that indicates the one or more NPCA switching modes supported by STA 1402. The first NPCA switching mode used / activated / enabled by STA 1402 may correspond to one of the one or more NPCA switching modes supported by STA 1402. In an example, the one or more NPCA switching modes supported by STA 1402 include the first mode (Mode 1) and / or the second mode (Mode 2) described above. In an embodiment, where STA 1402 supports more than one NPCA switching modes, STA 1402 may activate / enable more than one NPCA switching modes. STA 1402 may indicate the more than one NPCA switching modes in frame 1410. STA 1402 may use different NPCA switching modes of the more than one NPCA switching modes in different scenarios. For example, STA 1402 may support and activate / enable both the first mode (Mode 1) and the second mode (Mode 2). STA 1402 may use the first mode (Mode 1) when the OBSS PPDU comprises a VHT PPDU, an HE PPDU, an EHT PPDU, or a UHR PPDU, and may use the second mode (Mode 2) when the OBSS PPDU comprises an HT PPDU.

[0136] After STAs 1402 and 1404 exchange frames 1408 and 1410, a transmission of a PPDU 1412 begins on the PCH. PPDU 1412 may be transmitted by a station that belongs to an OBSS relative to the BSS of STAs 1402 and 1404. As STAs 1402 and 1404 operate on the PCH, STAs 1402 and 1404 may (in parallel) detect / sense the transmission of PPDU 1412 and begin to read / decode OBSS PPDU 1412. In an example, STAs 1402 and 1404 may read / decode a PHY identifier field of PPDU 1412, which allows STAs 1402 and 1404 to determine a PPDU type of PPDU 1412. Next, STAs 1402 and 1404 may read / decode a BSS color field (or a BSSID field) of a signal (SIG) field of PPDU 1412. The SIG field may be comprised in a preamble art or a PHY header of PPDU 1412. Depending on the type of PPDU 1412, the SIG field may comprise a U-SIG, a UHR SIG, an EHT SIG, an HE SIG-A / B, a VHT SIG-A / B, or an HT SIG, for example.

[0137] Based on the BSS color field (or the BSSID field) of PPDU 1412 indicating a BSS that is different than the BSS of STAs 1402 and 1404, STAs 1402 and 1404 may detect that PPDU 1412 is an OBSS (or inter-BSS) PPDU. It is noted that STAs 1402 and 1404 may determine that PPDU 1412 is an OBSS PPDU before / without receiving PPDU 1412 fully.

[0138] In an embodiment, based on detecting that PPDU 1412 is an OBSS PPDU, STAs 1402 and 1404 may apply respectively the first NPCA switching mode and the second NPCA switching mode to determine when to switch from the PCH to the NPCA PCH. Specifically, based on detecting that PPDU 1412 is an OBSS PPDU, STA 1402 may switch from the PCH to the NPCA PCH at the first time indicated by the first NPCA switching mode used by STA 1402. Similarly, based on detecting that PPDU 1412 is an OBSS PPDU, STA 1404 may switch from the PCH to the NPCA PCH at the second time indicated by the second NPCA switching mode used by STA 1404.

[0139] In example 1400, as the first NPCA switching mode used by STA 1402 and the second NPCA switching mode used by STA 1404 are the same at detection of OBSS PPDU 1412 (both correspond to Mode 1), the first time and the second time correspond to the same time instant and STAs 1402 and 1404 switch at the same time (tl) from the PCH to the NPCA PCH as shown in FIG. 14. In an embodiment, based on the first NPCA switching mode and the second NPCA switching mode corresponding to Mode 1 described above, STAs 1402 and 1404 switch from the PCH to the NPCA PCH after finishing reading / decoding a TXOP field of the SIG field of PPDU 1412. In another embodiment, based on the first NPCA switching mode and the second NPCA switching mode corresponding to Mode 1 described above, STAs 1402 and 1404 switch from the PCH to the NPCA PCH after finishing reading / decoding the SIG field of PPDU 1412.

[0140] Continuing with example 1400, after switching to the NPCA PCH, STA 1402 may access the NPCA PCH and transmit a frame 1414 to STA 1404. As shown in FIG. 14, frame 1414 may be transmitted via a bandwidth that comprises the NPCA PCH. For example, frame 1414 may be transmitted via the NPCH PCH and SCH2. In an embodiment, STA 1402 may transmit frame 1414 at a transmission time based on the second NPCA switching mode used by STA 1404 (or based on the second time indicated by the second NPCA switching mode). Specifically, in example 1400, knowing that STA 1404 switched to (or is expected to switch to) the NPCA PCH at time tl (based on the second NPCA switching mode of STA 1404 indicated in frame 1408), STA 1402 may determine that STA 1404 is ready / available to receive via the NPCA PCH after time tl. STA 1402 may thus transmit frame 1414 at a transmission time based on tl (e.g., immediately after tl, after a random backoff from tl, etc.). Frame 1414 may comprise an initial control frame (ICF), a request-to-send (RTS) frame, a multi-user (MU)-RTS frame, a buffer status report poll (BSRP) trigger frame, a block ack request (BAR) frame, a clear-to-send (CTS) frame, a block ack (BA) frame, an acknowledgment (Ack) frame, a buffer status report (BSR) frame, an initial control response frame (ICR), a control frame, a management frame, or an action frame, for example. By transmitting frame 1414 at a transmission time based on the second NPCA switching mode used by STA 1404, loss of frame 1414 due to unavailability of STA 1404 to receive frame 1414 on the NPCA PCH is avoided.

[0141] In an embodiment, STA 1404 may respond to frame 1414 from STA 1402 by transmitting a frame 1416 to STA 1402. Frame 1416 may comprise a clear-to-send (CTS) frame, a BlockAck (BA) frame, an acknowledgment (Ack) frame, a buffer status report (BSR) frame, an initial control response frame (ICR), a control frame, a management frame, or an action frame, for example. Subsequently, STA 1402 may transmit a frame 1418 to STA 1404. Frame 1418 may comprise a data frame, a management frame, or an action frame, for example. STA 1404 may respond to frame 1418 by transmitting a frame 1420 to STA 1402. Frame 1420 may comprise an immediate response frame, such as an Ack frame or a BA frame. As such, successful communication may occur between STAs 1402 and 1404 on the NPCA PCH after STAs 1404 and 1404 switch to the NPCA PCH after detecting OBSS PPDU 1412. In an embodiment, STAs 1402 and 1404 may switch to the NPCA PCH as described above, without determining the OBSS NAV duration associated with OBSS PPDU 1412. Accordingly, STAs 1402 and 1404 may be configured to finish communicating on the NPCA PCH and return to the PCH before an end of OBSS PPDU 1412.

[0142] FIG. 15 shows an example 1500 that illustrates another example NPCA operation according to an embodiment. Example 1500 is provided for the purpose of illustration only and is not limiting of embodiments. As shown in FIG. 15, example 1500 also includes STAs 1402 and 1404 described in FIG. 14 above.

[0143] As shown in FIG. 15, example 1500 may being with STA 1402 transmitting a frame 1502. Frame 1502 may indicate a first NPCA switching mode used / activated / enabled by STA 1402. In an embodiment, STA 1402 may be an AP STA, and frame 1502 may comprise a beacon frame, a fast initial link setup (FILS) discovery frame, a short beacon frame, a traffic indication map (TIM) broadcast frame, a broadcast frame, or an announcement frame, for example.

[0144] In an embodiment, frame 1502 may indicate one or more NPCA switching modes supported by STA 1402. In an implementation, frame 1502 may comprise a capability element that indicates the one or more NPCA switching modes supported by STA 1402. The first NPCA switching mode used / activated / enabled by STA 1402 may correspond to one of the one or more NPCA switching modes supported by STA 1402. In an example, the one or more NPCA switching modes supported by STA 1402 include the first mode (Mode 1) and / or the second mode (Mode 2) described above. In an embodiment, where STA 1402 supports more than one NPCA switching modes, STA 1402 may activate / enable more than one NPCA switching modes. STA 1402 may indicate the more than one NPCA switching modes in frame 1502. STA 1402 may use different NPCA switching modes of the more than one NPCA switching modes in different scenarios. For example, STA 1402 may support and activate / enable both the first mode (Mode 1) and the second mode (Mode 2). STA 1402 may use the first mode (Mode 1) when the OBSS PPDU comprises a VHT PPDU, an HE PPDU, an EHT PPDU, or a UHR PPDU, and may use the second mode (Mode 2) when the OBSS PPDU comprises an HT PPDU. The first NPCA switching mode indicates a first time at which STA 1402 switches from the PCH to the NPCA PCH after detecting an OBSS PPDU on the PCH. In example 1500, the first NPCA switching mode used by STA 1402 corresponds to the second mode (Mode 2) described above. As mentioned above, according to the second mode, STA 1402 may be configured to switch from the PCH to the NPCA PCH after reading / decoding (or trying to read / decode) one or more MPDU (e.g., first occurring MPDU, a fixed number of first occurring MPDUs, etc.) of the OBSS PPDU. In an embodiment, STA 1402 may be configured to stop processing / decoding the PPDU being received on the PCH and to switch immediately to the NPCA PCH after reading / decoding the one or more MPDU of the PPDU. The first time indicated by the first NPCA switching mode may thus correspond to the time that STA 1402 finishes reading / decoding the one or more MPDU of the PPDU being received on the PCH. In another embodiment, STA 1402 may switch to the NPCA PCH after finishing reading / decoding a delimiter of a first occurring MPDU of the PPDU. The first time indicated by the first NPCA switching mode may thus correspond to the time that STA 1402 finishes reading / decoding the delimiter of the first occurring MPDU of the PPDU being received on the PCH.

[0145] Subsequently, example 1500 may include STA 1404 transmitting a frame 1504 to STA 1402. Frame 1504 may indicate a second NPCA switching mode used / activated / enabled by STA 1404. In an embodiment, frame 1504 comprises an operation mode field that indicates the second NPCA switching mode used / activated / enabled by STA 1404. Frame 1504 may comprise a probe request frame, an association request frame, a reassociation request frame, a request frame, a management frame, an action frame, a control frame, a quality of service (QoS) null frame, or a QoS data frame, for example. In an embodiment, where frame 1504 comprises a request frame, frame 1504 comprises a request from STA 1404 to STA 1402 to use the indicated second NPCA switching mode used / activated / enabled by STA 1404.

[0146] In an embodiment, frame 1504 may indicate one or more NPCA switching modes supported by STA 1404. In an implementation, frame 1504 may comprise a capability element that indicates the one or more NPCA switching modes supported by STA 1404. The second NPCA switching mode used / activated / enabled by STA 1404 may correspond to one of the one or more NPCA switching modes supported by STA 1404. In an example, the one or more NPCA switching modes supported by STA 1404 include the first mode (Mode 1) and / or the second mode (Mode 2) described above. In an embodiment, where STA 1404 supports more than one NPCA switching modes, STA 1404 may activate / enable more than one NPCA switching modes. STA 1404 may indicate the more than one NPCA switching modes in frame 1504. STA 1404 may use different NPCA switching modes of the more than one NPCA switching modes in different scenarios. For example, STA 1404 may support and activate / enable both the first mode (Mode 1) and the second mode (Mode 2). STA 1404 may use the first mode (Mode 1) when the OBSS PPDU comprises a VHT PPDU, an HE PPDU, an EHT PPDU, or a UHR PPDU, and may use the second mode (Mode 2) when the OBSS PPDU comprises an HT PPDU. In another example, STA 1404 may use one of Mode 1 and Mode 2 regardless of PPDU type.

[0147] The second NPCA switching mode indicates a second time at which STA 1404 switches from the PCH to the NPCA PCH after detecting an OBSS PPDU on the PCH. In example 1500, the second NPCA switching mode used by STA 1404 corresponds to the second mode (Mode 2) described above. As mentioned above, according to the second mode, STA 1404 may be configured to switch from the PCH to the NPCA PCH after reading / decoding (or trying to read / decode) one or more MPDU (e.g., first occurring MPDU, a fixed number of first occurring MPDUs, etc.) of the OBSS PPDU. In an embodiment, STA 1404 may be configured to stop processing / decoding the PPDU being received on the PCH and to switch immediately to the NPCA PCH after reading / decoding the one or more MPDU of the PPDU. The second time indicated by the second NPCA switching mode may thus correspond to the time that STA 1404 finishes reading / decoding the one or more MPDU of the PPDU being received on the PCH. In another embodiment, STA 1404 may be configured to stop processing / decoding the PPDU being received on the PCH and to switch immediately to the NPCA PCH after reading / decoding a first MPDU of the one or more MPDU of the PPDU. The second time indicated by the second NPCA switching mode may thus correspond to the time that STA 1404 finishes reading / decoding the first MPDU of the one or more MPDU of the PPDU being received on the PCH. In another embodiment, STA 1404 may switch to the NPCA PCH after finishing reading / decoding a delimiter of a first occurring MPDU of the PPDU. The second time indicated by the second NPCA switching mode may thus correspond to the time that STA 1404 finishes reading / decoding the delimiter of the first occurring MPDU of the PPDU being received on the PCH.

[0148] In an embodiment, STA 1402 may respond to frame 1504 from STA 1404 by transmitting a frame 1506 to STA 1404. In another embodiment, STA 1402 may not respond to frame 1504 from STA 1404. In an embodiment, frame 1506 acknowledges frame 1506. In another embodiment, frame 1506 responds to frame 1506. In an embodiment, frame 1506 indicates the first NPCA switching mode used / activated / enabled by STA 1402. In an embodiment, frame 1506 comprises an operation mode field that indicates the first NPCA switching mode used / activated / enabled by STA 1402. Frame 1506 may comprise a probe response frame, an association response frame, a reassociation response frame, a response frame, a management frame, an action frame, a control frame, a quality of service (QoS) null frame, or a QoS data frame, for example. In an embodiment, where frame 1504 comprises a request frame as described above, frame 1506 may comprise a response frame that comprises a response to the request from STA 1404 to STA 1402 to use the indicated second NPCA switching mode used / activated / enabled by STA 1404. The response may accept or reject the request comprised in frame 1504. For example, if STA 1402 supports the second NPCA switching mode indicated in frame 1504, STA 1402 may accept the request comprised in frame 1504. Conversely, if STA 1402 does not support the second NPCA switching mode indicated in frame 1504, STA 1402 may reject the request comprised in frame 1504.

[0149] In an embodiment, frame 1506 may indicate one or more NPCA switching modes supported by STA 1402. In an implementation, frame 1506 may comprise a capability element that indicates the one or more NPCA switching modes supported by STA 1402. The first NPCA switching mode used / activated / enabled by STA 1402 may correspond to one of the one or more NPCA switching modes supported by STA 1402. In an example, the one or more NPCA switching modes supported by STA 1402 include the first mode (Mode 1) and / or the second mode (Mode 2) described above. In an embodiment, where STA 1402 supports more than one NPCA switching modes, STA 1402 may activate / enable more than one NPCA switching modes. STA 1402 may indicate the more than one NPCA switching modes in frame 1506. STA 1402 may use different NPCA switching modes of the more than one NPCA switching modes in different scenarios. For example, STA 1402 may support and activate / enable both the first mode (Mode 1) and the second mode (Mode 2). STA 1402 may use the first mode (Mode 1) when the OBSS PPDU comprises a VHT PPDU, an HE PPDU, an EHT PPDU, or a UHR PPDU, and may use the second mode (Mode 2) when the OBSS PPDU comprises an HT PPDU. In an embodiment, where STA 1402 supports more than one NPCA switching modes, STA 1402 may activate / enable one NPCA switching mode. STA 1402 may indicate one NPCA switching mode in frame 1506. STA 1402 may use the same NPCA switching mode of the more than one NPCA switching modes in different scenarios. For example, STA 1402 may support and activate / enable both the first mode (Mode 1) and the second mode (Mode 2). STA 1402 may use the second mode (Mode 2) regardless of PPDU type.

[0150] After STAs 1402 and 1404 exchange frames 1504 and 1506, a transmission of a PPDU 1508 begins on the PCH. PPDU 1508 may be transmitted by a station that belongs to an OBSS relative to the BSS of STAs 1402 and 1404. As STAs 1402 and 1404 operate on the PCH, STAs 1402 and 1404 may (in parallel) detect / sense the transmission of PPDU 1508 and begin to read / decode OBSS PPDU 1508. In an example, STAs 1402 and 1404 may read / decode a PHY identifier field of PPDU 1508, which allows STAs 1402 and 1404 to determine a PPDU type of PPDU 1508. Next, STAs 1402 and 1404 may read / decode a BSS color field (or a BSSID field) of a signal (SIG) field of PPDU 1508. The SIG field may be comprised in a preamble art or a PHY header of PPDU 1508. Depending on the type of PPDU 1508, the SIG field may comprise a U-SIG, a UHR SIG, an EHT SIG, an HE SIG-A / B, a VHT SIG-A / B, or an HT SIG, for example.

[0151] Based on the BSS color field (or the BSSID field) of PPDU 1508 indicating a BSS that is different than the BSS of STAs 1402 and 1404, STAs 1402 and 1404 may detect that PPDU 1508 is an OBSS (or inter-BSS) PPDU. It is noted that STAs 1402 and 1404 may determine that PPDU 1508 is an OBSS PPDU before / without receiving PPDU 1508 fully.

[0152] In an embodiment, based on detecting that PPDU 1508 is an OBSS PPDU, STAs 1402 and 1404 may apply respectively the first NPC A switching mode and the second NPC A switching mode to determine when to switch from the PCH to the NPCA PCH. Specifically, based on detecting that PPDU 1508 is an OBSS PPDU, STA 1402 may switch from the PCH to the NPCA PCH at the first time indicated by the first NPCA switching mode used by STA 1402. Similarly, based on detecting that PPDU 1508 is an OBSS PPDU, STA 1404 may switch from the PCH to the NPCA PCH at the second time indicated by the second NPCA switching mode used by STA 1404.

[0153] In example 1500, as the first NPCA switching mode used by STA 1402 and the second NPCA switching mode used by STA 1404 are the same at detection of OBSS PPDU 1508 (both correspond to Mode 2), the first time and the second time correspond to the same time instant and STAs 1402 and 1404 switch at the same time (t2) from the PCH to the NPCA PCH as shown in FIG. 15. In an embodiment, based on the first NPCA switching mode and the second NPCA switching mode corresponding to Mode 2 described above, STAs 1402 and 1404 switch from the PCH to the NPCA PCH after finishing reading / decoding one or more MPDU (e.g., first occurring MPDU, a fixed number of first occurring MPDUs, etc.) of PPDU 1508. In another embodiment, based on the first NPCA switching mode and the second NPCA switching mode corresponding to Mode 2 described above, STAs 1402 and 1404 switch from the PCH to the NPCA PCH after finishing reading / decoding the delimiter of the first occurring MPDU (e.g., MPDUl) ofPPDU 1508.

[0154] Continuing with example 1500, after switching to the NPCA PCH, STA 1402 may access the NPCA PCH and transmit a frame 1510 to STA 1404. As shown in FIG. 15, frame 1510 may be transmitted via a bandwidth that comprises the NPCA PCH. For example, frame 1510 may be transmitted via the NPCH PCH and SCH2. In an embodiment, STA 1402 may transmit frame 1510 at a transmission time based on the second NPCA switching mode used by STA 1404 (or based on the second time indicated by the second NPCA switching mode). Specifically, in example 1500, knowing that STA 1404 switched to (or is expected to switch to) the NPCA PCH at time t2 (based on the second NPCA switching mode of STA 1404 indicated in frame 1506), STA 1402 may determine that STA 1404 is ready / available to receive via the NPCA PCH after time t2. STA 1402 may thus transmit frame 1510 at a transmission time based on t2 (e.g., immediately after t2, after a random backoff from t2, etc.). Frame 1510 may comprise an initial control frame (ICF), a request-to-send (RTS) frame, a multi-user (MU)-RTS frame, a buffer status report poll (BSRP) trigger frame, a block ack request (BAR) frame, a clear-to-send (CTS) frame, a block ack (BA) frame, an acknowledgment (Ack) frame, a buffer status report (BSR) frame, an initial control response frame (ICR), a control frame, a management frame, or an action frame, for example. By transmitting frame 1510 at a transmission time based on the second NPCA switching mode used by STA 1404, loss of frame 1510 due to unavailability of STA 1404 to receive frame 1510 on the NPCA PCH is avoided.

[0155] In an embodiment, STA 1404 may respond to frame 1510 from STA 1402 by transmitting a frame 1512 to STA 1402. Frame 1512 may comprise a clear-to-send (CTS) frame, a BlockAck (BA) frame, an acknowledgment (Ack) frame, a buffer status report (BSR) frame, an initial control response frame (ICR), a control frame, a management frame, or an action frame, for example. Subsequently, STA 1404 may transmit a frame 1514 to STA 1404. Frame 1514 may comprise a data frame, a management frame, or an action frame, for example. STA 1404 may respond to frame 1514 by transmitting a frame 1516 to STA 1402. Frame 1516 may comprise an immediate response frame, such as an Ack frame or a BA frame. As such, successful communication may occur between STAs 1402 and 1404 on the NPCA PCH after STAs 1404 and 1404 switch to the NPCA PCH after detecting OBSS PPDU 1508. In an embodiment, STAs 1402 and 1404 may switch to the NPCA PCH as described above, without determining the OBSS NAV duration associated with OBSS PPDU 1508. Accordingly, STAs 1402 and 1404 may be configured to finish communicating on the NPCA PCH and return to the PCH before an end of OBSS PPDU 1508.

[0156] FIG. 16 shows an example 1600 that illustrates another example NPCA operation according to an embodiment. Example 1600 is provided for the purpose of illustration only and is not limiting of embodiments. As shown in FIG. 16, example 1600 also includes STAs 1402 and 1404 described in FIG. 14 above.

[0157] As shown in FIG. 16, example 1600 may being with STA 1402 transmitting a frame 1602. Frame 1602 may indicate a first NPCA switching mode used / activated / enabled by STA 1402. In an embodiment, STA 1402 may be an AP STA, and frame 1602 may comprise a beacon frame, a fast initial link setup (FILS) discovery frame, a short beacon frame, a traffic indication map (TIM) broadcast frame, a broadcast frame, or an announcement frame, for example.

[0158] In an embodiment, frame 1602 may indicate one or more NPCA switching modes supported by STA 1402. In an implementation, frame 1602 may comprise a capability element that indicates the one or more NPCA switching modes supported by STA 1402. The first NPCA switching mode used / activated / enabled by STA 1402 may correspond to one of the one or more NPCA switching modes supported by STA 1402. In an example, the one or more NPCA switching modes supported by STA 1402 include the first mode (Mode 1) and / or the second mode (Mode 2) described above. In an embodiment, where STA 1402 supports more than one NPCA switching modes, STA 1402 may activate / enable more than one NPCA switching modes. STA 1402 may indicate the more than one NPCA switching modes in frame 1402. STA 1402 may use different NPCA switching modes of the more than one NPCA switching modes in different scenarios. For example, STA 1402 may support and activate / enable both the first mode (Mode 1) and the second mode (Mode 2). STA 1402 may use the first mode (Mode 1) when the OBSS PPDU comprises a VHT PPDU, an HE PPDU, an EHT PPDU, or a UHR PPDU, and may use the second mode (Mode 2) when the OBSS PPDU comprises an HT PPDU.

[0159] The first NPCA switching mode indicates a first time at which STA 1402 switches from the PCH to the NPCA PCH after detecting an OBSS PPDU on the PCH. In example 1600, the first NPCA switching mode used by STA 1402 corresponds to the first mode (Mode 1) described above. As mentioned above, according to the first mode, STA 1402 may be configured to switch from the PCH to the NPCA PCH after receiving / decoding a signal (SIG) field of a PPDU being received on the PCH and determining based on the SIG field that the PPDU is an OBSS PPDU. In an embodiment, where the PPDU being received on the PCH comprises an extremely high throughput (EHT) PPDU, an ultra-high reliability (UHR) PPDU, or a UHR+ PPDU, the SIG field comprises a universal SIG (U-SIG) field of the PPDU. In an embodiment, where the PPDU being received on the PCH comprises a high efficiency (HE) PPDU, the SIG field comprises an HE-SIG-A field of the PPDU. In an embodiment, where the PPDU being received on the PCH comprises a very high throughput (VHT) PPDU, the SIG field comprises a VHT-SIG-A field of the first OBSS PPDU. In an embodiment, STA 1402 may be configured to stop processing / decoding the PPDU being received on the PCH and to switch immediately to the NPCA PCH after reading the TXOP field of the SIG field of the PPDU. The first time indicated by the first NPCA switching mode may thus correspond to the time that STA 1402 finishes reading / decoding the TXOP field of the PPDU being received on the PCH. In another embodiment, STA 1402 may switch to the NPCA PCH after finishing reading / decoding the SIG field of the PPDU. The first time indicated by the first NPCA switching mode may thus correspond to the time that STA 1402 finishes reading / decoding the SIG field of the PPDU being received on the PCH.

[0160] Subsequently, example 1600 may include STA 1404 transmitting a frame 1604 to STA 1402. Frame 1604 may indicate a second NPCA switching mode used / activated / enabled by STA 1404. In an embodiment, frame 1604 comprises an operation mode field that indicates the second NPCA switching mode used / activated / enabled by STA 1404. Frame 1604 may comprise a probe request frame, an association request frame, a reassociation request frame, a request frame, a management frame, an action frame, a control frame, a quality of service (QoS) null frame, or a QoS data frame, for example. In an embodiment, where frame 1604 comprises a request frame, frame 1604 comprises a request from STA 1404 to STA 1402 to use the indicated second NPCA switching mode used / activated / enabled by STA 1404.

[0161] In an embodiment, frame 1604 may indicate one or more NPCA switching modes supported by STA 1404. In an implementation, frame 1604 may comprise a capability element that indicates the one or more NPCA switching modes supported by STA 1404. The second NPCA switching mode used / activated / enabled by STA 1404 may correspond to one of the one or more NPCA switching modes supported by STA 1404. In an example, the one or more NPCA switching modes supported by STA 1404 include the first mode (Mode 1) and / or the second mode (Mode 2) described above. In an embodiment, where STA 1404 supports more than one NPCA switching modes, STA 1404 may activate / enable more than one NPCA switching modes. STA 1404 may indicate the more than one NPCA switching modes in frame 1604. STA 1404 may use different NPCA switching modes of the more than one NPCA switching modes in different scenarios. For example, STA 1404 may support and activate / enable both the first mode (Mode 1) and the second mode (Mode 2). STA 1404 may use the first mode (Mode 1) when the OBSS PPDU comprises a VHT PPDU, an HE PPDU, an EHT PPDU, or a UHR PPDU, and may use the second mode (Mode 2) when the OBSS PPDU comprises an HT PPDU.

[0162] The second NPCA switching mode indicates a second time at which STA 1404 switches from the PCH to the NPCA PCH after detecting an OBSS PPDU on the PCH. In example 1600, the second NPCA switching mode used by STA 1404 corresponds to the second mode (Mode 2) described above. As mentioned above, according to the second mode, STA 1404 may be configured to switch from the PCH to the NPCA PCH after reading / decoding (or trying to read / decode) one or more MPDU (e.g., first occurring MPDU, a fixed number of first occurring MPDUs, etc.) of the OBSS PPDU. In an embodiment, STA 1404 may be configured to stop processing / decoding the PPDU being received on the PCH and to switch immediately to the NPCA PCH after reading / decoding the one or more MPDU of the PPDU. The second time indicated by the second NPCA switching mode may thus correspond to the time that STA 1404 finishes reading / decoding the one or more MPDU of the PPDU being received on the PCH. In another embodiment, STA 1404 may switch to the NPCA PCH after finishing reading / decoding a delimiter of a first occurring MPDU of the PPDU. The second time indicated by the second NPCA switching mode may thus correspond to the time that STA 1404 finishes reading / decoding the delimiter of the first occurring MPDU of the PPDU being received on the PCH.

[0163] In an embodiment, STA 1402 may respond to frame 1604 from STA 1404 by transmitting a frame 1606 to STA 1404. In another embodiment, STA 1402 may not respond to frame 1604 from STA 1404. In an embodiment, frame 1606 acknowledges frame 1606. In another embodiment, frame 1606 responds to frame 1606. In an embodiment, frame 1606 indicates the first NPCA switching mode used / activated / enabled by STA 1402. In an embodiment, frame 1606 comprises an operation mode field that indicates the first NPCA switching mode used / activated / enabled by STA 1402. Frame 1606 may comprise a probe response frame, an association response frame, a reassociation response frame, a response frame, a management frame, an action frame, a control frame, a quality of service (QoS) null frame, or a QoS data frame, for example. In an embodiment, where frame 1604 comprises a request frame as described above, frame 1606 may comprise a response frame that comprises a response to the request from STA 1404 to STA 1402 to use the indicated second NPCA switching mode used / activated / enabled by STA 1404. The response may accept or reject the request comprised in frame 1604. For example, if STA 1402 supports the second NPCA switching mode indicated in frame 1604, STA 1402 may accept the request comprised in frame 1604. Conversely, if STA 1402 does not support the second NPCA switching mode indicated in frame 1604, STA 1402 may reject the request comprised in frame 1604. In example 1600, it is assumed that STA 1402 accepts / acknowledges the second NPCA switching mode indicated in frame 1604.

[0164] In an embodiment, frame 1606 may indicate one or more NPCA switching modes supported by STA 1402. In an implementation, frame 1606 may comprise a capability element that indicates the one or more NPCA switching modes supported by STA 1402. The first NPCA switching mode used / activated / enabled by STA 1402 may correspond to one of the one or more NPCA switching modes supported by STA 1402. In an example, the one or more NPCA switching modes supported by STA 1402 include the first mode (Mode 1) and / or the second mode (Mode 2) described above. In an embodiment, where STA 1402 supports more than one NPCA switching modes, STA 1402 may activate / enable more than one NPCA switching modes. STA 1402 may indicate the more than one NPCA switching modes in frame 1606. STA 1402 may use different NPCA switching modes of the more than one NPCA switching modes in different scenarios. For example, STA 1402 may support and activate / enable both the first mode (Mode 1) and the second mode (Mode 2). STA 1402 may use the first mode (Mode 1) when the OBSS PPDU comprises a VHT PPDU, an HE PPDU, an EHT PPDU, or a UHR PPDU, and may use the second mode (Mode 2) when the OBSS PPDU comprises an HT PPDU.

[0165] After STAs 1402 and 1404 exchange frames 1604 and 1606, a transmission of a PPDU 1608 begins on the PCH. PPDU 1608 may be transmitted by a station that belongs to an OBSS relative to the BSS of STAs 1402 and 1404. As STAs 1402 and 1404 operate on the PCH, STAs 1402 and 1404 may (in parallel) detect / sense the transmission of PPDU 1608 and begin to read / decode OBSS PPDU 1608. In an example, STAs 1402 and 1404 may read / decode a PHY identifier field of PPDU 1608, which allows STAs 1402 and 1404 to determine a PPDU type of PPDU 1608. Next, STAs 1402 and 1404 may read / decode a BSS color field (or a BSSID field) of a signal (SIG) field of PPDU 1608. The SIG field may be comprised in a preamble art or a PHY header of PPDU 1608. Depending on the type of PPDU 1608, the SIG field may comprise a U-SIG, a UHR SIG, an EHT SIG, an HE SIG-A / B, a VHT SIG-A / B, or an HT SIG, for example.

[0166] Based on the BSS color field (or the BSSID field) of PPDU 1608 indicating a BSS that is different than the BSS of STAs 1402 and 1404, STAs 1402 and 1404 may detect that PPDU 1608 is an OBSS (or inter-BSS) PPDU. It is noted that STAs 1402 and 1404 may determine that PPDU 1608 is an OBSS PPDU before / without receiving PPDU 1608 fully.

[0167] In an embodiment, based on detecting that PPDU 1608 is an OBSS PPDU, STAs 1402 and 1404 may apply respectively the first NPCA switching mode and the second NPCA switching mode to determine when to switch from the PCH to the NPCA PCH. Specifically, based on detecting that PPDU 1608 is an OBSS PPDU, STA 1402 may switch from the PCH to the NPCA PCH at the first time indicated by the first NPCA switching mode used by STA 1402. Similarly, based on detecting that PPDU 1608 is an OBSS PPDU, STA 1404 may switch from the PCH to the NPCA PCH at the second time indicated by the second NPCA switching mode used by STA 1404.

[0168] In example 1600, as the first NPCA switching mode used by STA 1402 and the second NPCA switching mode used by STA 1404 are different (the first NPCA switching mode corresponding to Mode 1 and the second NPCA switching mode corresponding to Mode 2), the first time and the second time correspond to different time instants and STAs 1402 and 1404 switch at times tl and t2 respectively from the PCH to the NPCA PCH as shown in FIG. 16. In an embodiment, based on the first NPCA switching mode corresponding to Mode 1 described above, STA 1402 switches from the PCH to the NPCA PCH after finishing reading / decoding a TXOP field of the SIG field of PPDU 1608. In another embodiment, based on the first NPCA switching mode corresponding to Mode 1 described above, STA 1402 switches from the PCH to the NPCA PCH after finishing reading / decoding the SIG field of PPDU 1608. In an embodiment, based on the second NPCA switching mode corresponding to Mode 2 described above, STA 1404 switches from the PCH to the NPCA PCH after finishing reading / decoding one or more MPDU (e.g., first occurring MPDU, a fixed number of first occurring MPDUs, etc.) of PPDU 1608. In another embodiment, based on the second NPCA switching mode corresponding to Mode 2 described above, STA 1404 switches from the PCH to the NPCA PCH after finishing reading / decoding the delimiter of the first occurring MPDU (e.g., MPDU1) of PPDU 1608.

[0169] Continuing with example 1600, after switching to the NPCA PCH, STA 1402 may access the NPCA PCH and transmit a frame 1610 to STA 1404. As shown in FIG. 16, frame 1610 may be transmitted via a bandwidth that comprises the NPCA PCH. For example, frame 1610 may be transmitted via the NPCH PCH and SCH2. In an embodiment, STA 1402 may transmit frame 1610 at a transmission time based on the second NPCA switching mode used by STA 1404 (or based on the second time indicated by the second NPCA switching mode). Specifically, in example 1600, knowing that STA 1404 switched to (or is expected to switch to) the NPCA PCH at time t2 (based on the second NPCA switching mode of STA 1404 indicated in frame 1606), STA 1402 may determine that STA 1404 is ready / available to receive via the NPCA PCH after time t2. STA 1402 may thus transmit frame 1610 at a transmission time based on t2.

[0170] In an embodiment, STA 1402 may be configured to wait for a time period 1618 from the first time (e.g., time tl) at which STA 1402 switched to the NPCA PCH, before transmitting frame 1610 to STA 1404. In an embodiment, time period 1618 may be based on the second time (e.g., time t2) at which STA 1404 is expected to switch to the NPCA PCH. For example, as shown in FIG. 16, time period 1618 may extend until at least time t2. In an embodiment, time period 1618 may be further configured based on (or to account for) a switching delay of STA 1404 to switch from the PCH to the NPCA PCH. As such, STA 1402 may allow sufficient time for STA 1404 to switch to the NPCA PCH before transmitting frame 1610 to STA 1404. This increases the probability of STA 1404 receiving frame 1610 successfully. Frame 1610 may comprise an initial control frame (ICF), a request-to-send (RTS) frame, a multi-user (MU)-RTS frame, a buffer status report poll (BSRP) trigger frame, a block ack request (BAR) frame, a clear-to-send (CTS) frame, a block ack (BA) frame, an acknowledgment (Ack) frame, a buffer status report (BSR) frame, an initial control response frame (ICR), a control frame, a management frame, or an action frame, for example. In an embodiment, after switching to the NPCA PCH, STA 1404 may be configured to wait to receive a frame from STA 1402 before transmitting to STA 1402 on the NPCA PCH.

[0171] In an embodiment, STA 1404 may respond to frame 1610 from STA 1402 by transmitting a frame 1612 to STA 1402. Frame 1612 may comprise a clear-to-send (CTS) frame, a BlockAck (BA) frame, an acknowledgment (Ack) frame, a buffer status report (BSR) frame, an initial control response frame (ICR), a control frame, a management frame, or an action frame, for example. Subsequently, STA 1404 may transmit a frame 1614 to STA 1404. Frame 1614 may comprise a data frame, a management frame, or an action frame, for example. STA 1404 may respond to frame 1614 by transmitting a frame 1616 to STA 1402. Frame 1616 may comprise an immediate response frame, such as an Ack frame or a BA frame. As such, successful communication may occur between STAs 1402 and 1404 on the NPCA PCH after STAs 1404 and 1404 switch to the NPCA PCH after detecting OBSS PPDU 1608. In an embodiment, STAs 1402 and 1404 may switch to the NPCA PCH as described above, without determining the OBSS NAV duration associated with OBSS PPDU 1608. Accordingly, STAs 1402 and 1404 may be configured to finish communicating on the NPCA PCH and return to the PCH before an end of OBSS PPDU 1608.

[0172] In an embodiment, after switching to the NPCA PCH and during time period 1618, STA 1402 may communicate with another STA (not shown in FIG. 16). The other STA may belong to the same BSS as STA 1402. The other STA may be a STA that switched to the NPCA PCH at time tl, together with STA 1402, after detecting OBSS PPDU 1608. STA 1402 may have information regarding the time at which the other STA is configured to switch from the PCH to the NPCA PCH based on detecting an OBSS PPDU on the PCH, based on receiving a frame, similar to frame 1604, from the other STA.

[0173] FIG. 17 shows an example 1700 that illustrates another example NPCA operation according to an embodiment. Example 1700 is provided for the purpose of illustration only and is not limiting of embodiments. As shown in FIG. 17, example 1700 also includes STAs 1402 and 1404 described in FIG. 14 above. Example 1700 is similar to example 1600 described above. Specifically, as shown in FIG. 17, STAs 1402 and 1404 switch to the NPCA PCH at times tl and t2 respectively after detecting OBSS PPDU 1608.

[0174] In the embodiment illustrated in FIG. 17, STA 1404 may be configured, after switching to the NPCA PCH (after detecting OBSS PPDU 1608) to transmit a frame to STA 1402. STA 1402 may be configured to wait for a time period 1710 from the first time (e.g., time tl) at which STA 1402 switched to the NPCA PCH to receive the frame from STA 1404. Time period 1710 may be set similarly to time period 1618 described above. STA 1402 may be further configured, if STA 1402 does not receive a frame from STA 1404 during time period 1710, to transmit a frame (similar to frame 1610 described above) to STA 1404.

[0175] Accordingly, in example 1700, after switching to the NPCA PCH at time t2, STA 1404 transmits a frame 1702 to STA 1402. Frame 1702 may comprise a control frame, a data frame, a management frame, a QoS null frame, a QoS data frame, or an action frame, for example. STA 1402 may respond to frame 1702 by transmitting a frame 1704 to STA 1404. Frame 1704 may comprise an immediate response frame, such as an Ack frame or BA frame. Subsequently, STA 1404 may transmit a frame 1706 to STA 1404. Frame 1706 may comprise a data frame, a management frame, or an action frame, for example. STA 1404 may respond to frame 1706 by transmitting a frame 1708 to STA 1402. Frame 1708 may comprise an immediate response frame, such as an Ack frame or a BA frame. In an embodiment (not shown in FIG. 17), STA 1402 may transmit to STA 1404 a frame, similar to frame 1414, 1510, or 1610, before transmitting frame 1706 to STA 1404. In another embodiment, based on receiving frame 1702 from STA 1404, STA 1402 may not transmit frame 1704 before transmitting frame 1706 to STA 1404. For example, STA 1402 may transmit to STA 1404 frame 1706 in response to frame 1702.

[0176] FIG. 18 shows an example 1800 that illustrates another example NPCA operation according to an embodiment. Example 1800 is provided for the purpose of illustration only and is not limiting of embodiments. As shown in FIG. 18, example 1800 also includes STAs 1402 and 1404 described in FIG. 14 above.

[0177] Example 1800 may begin with STAs 1402 and 1404 exchanging frames 1408 and 1410, followed by STAs 1402 and 1404 detecting OBSS PPDU 1412 on the PCH and switching together at time tl (using Mode 1) to the NPCA PCH, as described in FIG. 14 above. After switching to the NPCA PCH, STA 1402 and 1404 may exchange frames 1414, 1416, 1418, and 1420 on the NPCA PCH, as described in FIG. 14 above. STAs 1402 and 1404 may return to the PCH by the end of OBSS PPDU 1412.

[0178] Subsequently, STA 1404 may transmit a frame 1802 to STA 1402 indicating an operation mode change by STA 1404. Specifically, frame 1802 may indicate an operation mode change at STA 1404 from the second NPCA switching mode (indicated in frame 1408 and used to switch to the NPCA PCH in response to OBSS PPDU 1412) to a third NPCA switching mode different than the second NPCA switching mode. For example, with the second NPCA switching mode corresponding to Mode 1, frame 1802 may indicate an operation mode change at STA 1404 from Mode 1 to Mode 2. In an embodiment, frame 1802 may comprise a request from STA 1404 to STA 1402 to change the operation mode at STA 1404. In embodiments, frame 1802 may comprise a control frame, a management, an action frame, a QoS null frame, or a QoS data frame, for example.

[0179] STA 1402 may respond to frame 1802 by transmitting a frame 1804 to STA 1404. In an embodiment, frame 1804 may acknowledge frame 1804. In another embodiment, where frame 1802 comprises a request from STA 1404 to STA 1402 to change the operation mode at STA 1404, frame 1804 may comprise a response to the request from STA 1404. The response may accept or reject the request to change the operation mode at STA 1404 to the third NPCA switching mode. Frame 1804 may comprise a control frame, a management, an action frame, a QoS null frame, or a QoS data frame, for example.

[0180] In example 1800, it is assumed that frame 1804 acknowledges or accepts the operation mode change at STA 1404 from the second NPCA switching mode (Mode 1) to the third NPCA switching mode (e.g., Mode 2). As such, STA 1404 may begin using the third NPCA switching mode (e.g., Mode 2) after receiving frame 1804 from STA 1402. Subsequently, STAs 1402 and 1404 may detect OBSS PPDU 1608 described in FIG. 16 above on the PCH. On detecting OBSS PPDU 1608, STAs 1402 and 1404 may switch to the NPCA PCH according to respectively the first NPCA switching mode (indicated in frame 1410 and used by STA 1402) and the third NPCA switching mode (indicated in frame 1802 and used by STA 1404 after receiving frame 1804). Specifically, as shown in FIG. 18, STA 1402 may switch to the NPCA PCH at a time t2 based on the first NPCA switching mode (Mode 1) used by STA 1402, and STA 1404 may switch to the NPCA PCH at a time t3 based on the third NPCA switching mode (e.g., Mode 2) used by STA 1404. After STA 1404 switches to the NPCA PCH, STA 1402 and 1404 may exchange frames 1610, 1612, 1614, and 1616 on the NPCA PCH, as described in FIG. 16 above. STAs 1402 and 1404 may return to the PCH by the end of OBSS PPDU 1608.

[0181] In another example (not shown in FIG. 18), after STAs 1402 and 1404 return to the PCH after detecting OBSS PPDU 1412, STA 1402 may transmit to STA 1404 a frame indicating a change of operation mode by STA 1402 (e.g., Mode 1 to Mode 2) and / or requesting a change of operation mode at STA 1404 (e.g., from Mode 1 to Mode 2). In response, STA 1404 may transmit to STA 1402 a frame acknowledging the change of operation mode by STA 1402 where frame 1402 indicates a change of operation mode by STA 1402 and / or accepting / rejecting the change of operation mode where frame 1402 requests a change of operation mode at STA 1404.

[0182] FIG. 19 shows an example 1900 that illustrates another example NPCA operation according to an embodiment. Example 1900 is provided for the purpose of illustration only and is not limiting of embodiments. As shown in FIG. 19, example 1900 includes STAs 1402 and 1404, described in FIG. 14, above, a STA 1902. STA 1902 may belong to the same BSS as STAs 1402 and 1404. STA 1902 may be an AP STA or a non-AP STA. In an embodiment, where STA 1402 is an AP STA and STA 1902 is a non-AP STA, STA 1902 may be associated with STA 1402. Like STAs 1402 and 1404, STA 1902 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). Additionally, STA 1902 may support one or more NPCA switching modes. The one or more NPCA switching modes may include the first mode (Mode 1) described above and the second mode (Mode 2) described above.

[0183] As shown in FIG. 19, example 1900 may begin with STA 1402 transmitting frame 1406, followed by STAs 1402 and 1404 exchanging frames 1408 and 1410, as described above in FIG. 14. As mentioned above, frame 1406 and / or frame 1410 indicate a first NPCA switching mode used by STA 1402 as corresponding to Mode 1 described above. Frame 1408 indicates a second NPCA switching mode used by STA 1404 as corresponding to Mode 1.

[0184] Subsequently, example 1900 may include STA 1902 transmitting a frame 1904 to STA 1402. Frame 1904 may indicate a third NPCA switching mode used / activated / enabled by STA 1902. In an embodiment, frame 1904 comprises an operation mode field that indicates the third NPCA switching mode used / activated / enabled by STA 1902. Frame 1904 may comprise a probe request frame, an association request frame, a reassociation request frame, a management frame, an action frame, a control frame, a quality of service (QoS) null frame, or a QoS data frame, for example.

[0185] In an embodiment, frame 1904 may indicate one or more NPCA switching modes supported by STA 1902. In an implementation, frame 1904 may comprise a capability element that indicates the one or more NPCA switching modes supported by STA 1902. The third NPCA switching mode used / activated / enabled by STA 1902 may correspond to one of the one or more NPCA switching modes supported by STA 1902. In an example, the one or more NPCA switching modes supported by STA 1902 include the first mode (Mode 1) and / or the second mode (Mode 2) described above.

[0186] The third NPCA switching mode indicates a third time at which STA 1902 switches from the PCH to the NPCA PCH after detecting an OBSS PPDU on the PCH. In example 1900, the third NPCA switching mode used by STA 1902, and indicated in frame 1904, corresponds to the second mode (Mode 2) described above. In an embodiment, STA 1402 may respond to frame 1904 from STA 1902 by transmitting a frame 1906 to STA 1902. In an embodiment, where the third NPCA switching mode indicated in frame 1904 is the same as the first NPCA switching mode used by STA 1402 (indicated in frame 1406 and / or frame 1410), frame 1906 may acknowl edge / accept the third NPCA switching mode indicated in frame 1904 by STA 1902. Conversely, if the third NPCA switching mode indicated in frame 1904 is different than the first NPCA switching mode used by STA 1402, frame 1906 may recommend that STA 1902 use the first NPCA switching mode as the third NPCA switching mode. In response to frame 1906, STA 1902 may transmit to STA 1402 a frame 1908 accepting or rejecting the recommendation to use the first NPCA switching mode as the third NPCA switching mode. In example 1900, with the third NPCA switching mode indicated by STA 1902 in frame 1904 (and corresponding to Mode 2) being different than the first NPCA switching mode used by STA 1402 (and corresponding to Mode 1), STA 1402 may recommend in frame 1906 that STA 1902 use the first NPCA switching mode (corresponding to Mode 1) as the third NPCA switching mode. In example 1900, STA 1902 accepts the recommendation of STA 1402 in frame 1908.

[0187] Subsequently, a transmission of a PPDU 1910 begins on the PCH. PPDU 1910 may be transmitted by a station that belongs to an OBSS relative to the BSS of STAs 1402, 1404, and 1902. As STAs 1402, 1404, and 1902 operate on the PCH, STAs 1402, 1404, and 1902 may (in parallel) detect / sense the transmission of PPDU 1910 and begin to read / decode OBSS PPDU 1910. In an example, STAs 1402, 1404, and 1902 may read / decode a PHY identifier field of PPDU 1910, which allows 1402, 1404, and 1902 to determine a PPDU type of PPDU 1910. Next, STAs 1402, 1404, and 1902 may read / decode a BSS color field (or a BSSID field) of a signal (SIG) field of PPDU 1910. The SIG field may be comprised in a preamble art or a PHY header of PPDU 1910. Depending on the type of PPDU 1910, the SIG field may comprise a U- SIG, a UHR SIG, an EHT SIG, an HE SIG-A / B, a VHT SIG-A / B, or an HT SIG, for example.

[0188] Based on the BSS color field (or the BSSID field) of PPDU 1910 indicating a BSS that is different than the BSS of STAs 1402, 1404, and 1902, STAs 1402, 1404, and 1902 may detect that PPDU 1910 is an OBSS (or inter-BSS) PPDU. It is noted that STAs 1402, 1404, and 1902 may determine that PPDU 1910 is an OBSS PPDU before / without receiving PPDU 1910 fully.

[0189] In an embodiment, based on detecting that PPDU 1910 is an OBSS PPDU, STAs 1402, 1404, and 1902 may apply respectively the first NPCA switching mode, the second NPCA switching mode, and the third NPCA switching mode to determine when to switch from the PCH to the NPCA PCH. Specifically, based on detecting that PPDU 1910 is an OBSS PPDU, STA 1402 may switch from the PCH to the NPCA PCH at the first time indicated by the first NPCA switching mode used by STA 1402; STA 1404 may switch from the PCH to the NPCA PCH at the second time indicated by the second NPCA switching mode used by STA 1404; and STA 1902 may switch from the PCH to the NPCA PCH at the third time indicated by the third NPCA switching mode used by STA 1902.

[0190] In example 1900, as the first NPCA switching mode used by STA 1402, the second NPCA switching mode used by STA 1404, and the third NPCA switching mode used by STA 1902 are the same at detection of OBSS PPDU 1910 (all correspond to Mode 1), the first time, the second time, and the third time correspond to the same time instant and STAs 1402, 1404, and 1902 switch at the same time (tl) from the PCH to the NPCA PCH as shown in FIG. 19. In an embodiment, based on the first NPCA switching mode, the second NPCA switching mode, and the third NPCA switching mode corresponding to Mode 1 described above, STAs 1402, 1404, and 1902 switch from the PCH to the NPCA PCH after finishing reading / decoding a TXOP field of the SIG field of PPDU 1910. In another embodiment, based on the first NPCA switching mode, the second NPCA switching mode, and the third NPCA switching mode corresponding to Mode 1 described above, STAs 1402, 1404, and 1902 switch from the PCH to the NPCA PCH after finishing reading / decoding the SIG field of PPDU 1910.

[0191] Continuing with example 1900, after switching to the NPCA PCH, STA 1402 may access the NPCA PCH and transmit a frame 1912 to STAs 1404 and 1902. As shown in FIG. 19, frame 1912 may be transmitted via a bandwidth that comprises the NPCA PCH. For example, frame 1912 may be transmitted via the NPCA PCH and SCH2. In an embodiment, STA 1402 may transmit frame 1912 at a transmission time based on the second NPCA switching mode used by STA 1404 (or based on the second time indicated by the second NPCA switching mode) and / or the third NPCA switching mode used by STA 1902 (or based on the third time indicated by the third NPCA switching mode). Specifically, in example 1900, knowing that STAs 1404 and 1902 switched to (or are expected to switch to) the NPCA PCH at time tl (based on the second NPCA switching mode of STA 1404 indicated in frame 1408 and STA 1902 accepting the recommendation to use the first NPCA switching mode as the third NPCA switching mode), STA 1402 may determine that STAs 1404 and 1902 are ready / available to receive via the NPCA PCH after time tl. STA 1402 may thus transmit frame 1912 at a transmission time based on tl (e.g., immediately after tl, after a random backoff from tl, etc.). Frame 1912 may comprise an initial control frame (ICF), a request-to-send (RTS) frame, a multi-user (MU)-RTS frame, a buffer status report poll (BSRP) trigger frame, a block ack request (BAR) frame, a clear-to-send (CTS) frame, a block ack (BA) frame, an acknowledgment (Ack) frame, a buffer status report (BSR) frame, an initial control response frame (ICR), a control frame, a management frame, or an action frame, for example. By transmitting frame 1912 at a transmission time based on the second NPCA switching mode used by STA 1404 and the third NPCA switching mode used by STA 1902, loss of frame 1912 due to unavailability of STA 1404 and / or STA 1902 to receive frame 1912 on the NPCA PCH is avoided.

[0192] In an embodiment, STAs 1404 and 1902 may respond to frame 1912 from STA 1402 by transmitting (e.g., simultaneously) frames 1914a and 1914b respectively to STA 1402. Frames 1914a and 1914b may comprise a clear-to-send (CTS) frame, a BlockAck (BA) frame, an acknowledgment (Ack) frame, a buffer status report (BSR) frame, an initial control response frame (ICR), a control frame, a management frame, or an action frame, for example. Subsequently, STA 1402 may transmit a frame 1916 to STAs 1404 and 1902. Frame 1916 may comprise a data frame, a management frame, or an action frame, for example. In an example frame 1418 may comprise a multi-user (MU) data frame. Frame 1916 may be transmitted using OFDMA or MU-MIMO. STAs 1404 and 1902 may respond to frame 1916 by transmitting frames 1918a and 1918b respectively to STA 1402. Frames 1918a and 1918b may comprise an immediate response frame, such as an Ack frame or a BA frame. In an embodiment, STAs 1402, 1404, and 1902 may switch to the NPCA PCH as described above, without determining the OBSS NAV duration associated with OBSS PPDU 1910. Accordingly, STAs 1402, 1404, and 1902 may be configured to finish communicating on the NPCA PCH and return to the PCH before an end of OBSS PPDU 1910.

[0193] FIG. 20 illustrates an 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 STA, such as STA 1402, for example. The first STA may comprise an AP STA or a non-AP STA. As shown in FIG. 20, example process 2000 may include steps 2002, 2004, and 2006.

[0194] Step 2002 includes detecting, by the STA and via a primary channel, an OBSS PPDU.

[0195] Step 2004 includes, after detecting the OBSS PPDU, switching, by first STA, from the primary channel to an NPCA primary channel based on a first NPCA switching mode used by the first STA.

[0196] Step 2006 includes transmitting, by the first STA to a second STA, a first frame via a bandwidth comprising the NPCA primary channel. The second STA may comprise an AP STA or a non-AP STA. In an embodiment, the second STA may belong to the same BSS as the first STA. In an embodiment, where the first STA comprises an AP STA and the second STA comprises a non- AP STA, the second STA may be associated with the first STA. In an embodiment, a transmission time of the first frame is based on a second NPCA switching mode used by the second STA.

[0197] In an embodiment, the first frame comprises an initial control frame (ICF), a request-to-send (RTS) frame, a multi-user (MU)-RTS frame, a buffer status report poll (BSRP) trigger frame, a block ack request (BAR) frame, a clear-to-send (CTS) frame, a block ack (BA) frame, an acknowledgment (Ack) frame, a buffer status report (BSR) frame, an initial control response frame (ICR), a control frame, a management frame, or an action frame.

[0198] In an embodiment, process 2000 may further comprise transmitting, by the first STA, a second frame indicating the first NPCA switching mode. The second frame may comprise a beacon frame, a fast initial link setup (FILS) discovery frame, a short beacon frame, a traffic indication map (TIM) broadcast frame, a broadcast frame, or an announcement frame.

[0199] In an embodiment, process 2000 may further comprise receiving, by the first STA from the second STA, a third frame indicating the second NPCA switching mode. In an embodiment, the third frame comprises a probe request frame, an association request frame, a reassociation request frame, a request frame, 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 third frame comprises a capability element that indicates one or more NPCA switching modes supported by the second STA. In an embodiment, the third frame comprises an operation mode field indicating the second NPCA switching mode being used by the second STA.

[0200] In an embodiment, process 2000 may further comprise, in response to the third frame, transmitting, by the first STA to the second STA, a fourth frame indicating the first NPCA switching mode. In an embodiment, the fourth frame comprises a probe response frame, an association response frame, a reassociation response frame, a response frame, 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 capability element that indicates one or more NPCA switching modes supported by the first STA. In an embodiment, the fourth frame comprises an operation mode field indicating the first NPCA switching mode being used by the first STA.

[0201] In an embodiment, the first NPCA switching mode indicates a first time at which the first STA switches from the primary channel to the NPCA primary channel after detecting a first OBSS PPDU on the primary channel. The first NPCA switching mode may correspond to Mode 1 or Mode 2 as described above. In an embodiment, the first time occurs after the first STA decodes a signal (SIG) field of the first OBSS PPDU. In an embodiment, where the first OBSS PPDU comprises an extremely high throughput (EHT) PPDU, an ultra-high reliability (UHR) PPDU, or a UHR+ PPDU, the SIG field comprises a universal SIG (U-SIG) field of the first OBSS PPDU. In an embodiment, where the first OBSS PPDU comprises a high efficiency (HE) PPDU, the SIG field comprises an HE- SIG-A field of the first OBSS PPDU. In an embodiment, where the first OBSS PPDU comprises a very high throughput (VHT) PPDU, the SIG field comprises a VHT-SIG-A field of the first OBSS PPDU.

[0202] In another embodiment, the first time occurs after the first STA decodes a first medium access control (MAC) protocol data unit (MPDU) of the first OBSS PPDU. The first OBSS PPDU may comprise a high throughput (HT) PPDU, a very high throughput (VHT) PPDU, a high efficiency (HE) PPDU, an extremely high throughput (EHT) PPDU, an ultra-high reliability (UHR) PPDU, or a UHR+ PPDU.

[0203] In an embodiment, the second NPCA switching mode indicates a second time at which the second STA switches from the primary channel to the NPCA primary channel after detecting a second OBSS PPDU on the primary channel. The second NPCA switching mode may correspond to Mode 1 or Mode 2 as described above.

[0204] In an embodiment, the second time occurs after the second STA decodes a signal (SIG) field of the second OBSS PPDU. In an embodiment, where the second OBSS PPDU comprises an extremely high throughput (EHT) PPDU, an ultra-high reliability (UHR) PPDU, or a UHR+ PPDU, the SIG field comprises a universal SIG (U-SIG) field of the second OBSS PPDU. In an embodiment, where the second OBSS PPDU comprises a high efficiency (HE) PPDU, the SIG field comprises an HE-SIG-A field of the second OBSS PPDU. In an embodiment, where the second OBSS PPDU comprises a very high throughput (VHT) PPDU, the SIG field comprises a VHT-SIG-A field of the second OBSS PPDU.

[0205] In another embodiment, the second time occurs after the second STA decodes a first medium access control (MAC) protocol data unit (MPDU) of the second OBSS PPDU. The second OBSS PPDU may comprise a high throughput (HT) PPDU, a very high throughput (VHT) PPDU, a high efficiency (HE) PPDU, an extremely high throughput (EHT) PPDU, an ultra-high reliability (UHR) PPDU, or a UHR+ PPDU.

[0206] The first OBSS PPDU may be the same as the second OBSS PPDU. That is, the first STA and the second STA may detect the same PPDU as an OBSS PPDU. On detecting the OBSS PPDU, the first STA may switch at the first time after detecting the OBSS PPDU and the second STA may switch at the second time after detecting the OBSS PPDU.

[0207] In an embodiment, process 2000 may further comprise receiving, by the first STA from the second STA, a fifth frame in response to the first frame. In an embodiment, the fifth frame comprises a clear-to-send (CTS) frame, a BlockAck (BA) frame, an acknowledgment (Ack) frame, a buffer status report (BSR) frame, an initial control response frame (ICR), a control frame, a management frame, or an action frame.

[0208] In an embodiment, process 2000 may further comprise transmitting, by the first STA to the second STA, a sixth frame. In an embodiment, transmitting the sixth frame is after or in response to receiving the fifth frame. In an embodiment, the sixth frame comprises a data frame, a management frame, or an action frame.

[0209] In an embodiment, process 2000 may further comprise receiving, by the first STA from the second STA, a seventh frame in response to the sixth frame. In an embodiment, the seventh frame comprises an immediate response frame.

[0210] In an embodiment, process 2000 may further comprise switching, by the first STA, from the NPCA primary channel to the primary channel before an end of the OBSS PPDU.

[0211] In an embodiment, the first time at which the first STA switches to the NPCA primary channel after detecting an OBSS PPDU on the primary channel is different from the second time at which the first STA switches to the NPCA primary channel after detecting the OBSS PPDU on the primary channel. In an embodiment, where the first time is different than the second time, the transmission time of the first frame is based on the second time.

[0212] In an embodiment, where the first time is earlier than the second time, transmitting the first frame may comprise transmitting the first frame after an end of a first time period from the first time. The first time period may be configured based on a switching delay of the second STA to switch from the primary channel to the NPCA primary channel. In an embodiment, process 2000 may further comprise transmitting, by the first STA to a third STA, a frame during the first time period. The third STA may be associated with the first STA.

[0213] In an embodiment, the transmitting of the first frame after the end of the first time period is based on not receiving an eighth frame from the second STA during the first time period. The eighth frame may comprise a control frame, a data frame, a management frame, or an action frame. In an embodiment, the first STA does not transmit to the second STA the first frame based on receiving the eighth frame. In an embodiment, process 2000 may further comprise receiving, by the first STA from the second STA and during the first time period, the eighth frame; and in response to the eighth frame, transmitting, by the first STA to the second STA, an immediate response frame. In an embodiment, process 2000 may further comprise, after the immediate response frame, transmitting, by the first STA to the second STA, a ninth frame. In an embodiment, the ninth frame may be the same as the sixth frame. In an embodiment, process 2000 may further comprise, in response to the ninth frame, receiving, by the first STA to the second STA, a tenth frame. In an embodiment, the tenth frame may be the same as the seventh frame.

[0214] In an embodiment, the fourth frame comprise a recommendation by the first STA to the second STA to use an NPCA switching mode as the second NPCA switching mode. In an embodiment, process 2000 may further comprise receiving, by the first STA from the second STA, an eleventh frame in response to the fourth frame. In an embodiment, the eleventh frame indicates acceptance or rejection of the first NPCA switching mode by the second STA.

[0215] In an embodiment, the first NPCA switching mode and the second NPCA switching mode may be the same. In an embodiment, where the first NPCA switching mode and the second NPCA switching mode are the same, process 2000 may further comprise transmitting, by the first STA to the second STA, a twelfth frame indicating an operation mode change by the first STA from the first NPCA switching mode to a third NPCA switching mode different than the first NPCA switching mode. In an embodiment, the twelfth frame comprises a control frame, a management, an action frame, a QoS null frame, or a QoS data frame. In an embodiment, process 2000 may further comprise, in response to the twelfth frame, receiving, by the first STA from the second STA, a thirteenth frame indicating acceptance or rejection of the third NPCA switching mode. In an embodiment, the thirteenth frame comprises a control frame, a management, an action frame, a QoS null frame, or a QoS data frame.

[0216] In another embodiment, where the first NPCA switching mode and the second NPCA switching mode are the same, process 2000 may further comprise receiving, by the first STA from the second STA, a fourteenth frame indicating an operation mode change by the second STA from the second NPCA switching mode to a fourth NPCA switching mode different than the second NPCA switching mode. In an embodiment, the fourteenth frame comprises a control frame, a management, an action frame, a QoS null frame, or a QoS data frame. In an embodiment, process 2000 may further comprise, in response to the thirteenth frame, transmitting, by the first STA to the second STA, a fifteenth frame indicating acceptance or rejection of the fourth NPCA switching mode. In an embodiment, the fifteenth frame comprises a control frame, a management, an action frame, a QoS null frame, or a QoS data frame. In an embodiment, the detecting of the OBSS PPDU in step 2002 comprises determining by the first STA that a PPDU being received by the first STA is transmitted by a station belonging to an OBSS before receiving the PPDU fully.

[0217] In an embodiment, the detecting of the OBSS PPDU in step 2002 comprises decoding ( / receiving / reading / parsing) by the first STA a part of a PPDU being received by the first STA to determine if the PPDU is an inter-BSS PPDU. In an embodiment, the decoding ( / receiving / reading / parsing) of the part of the PPDU being received by the first STA comprises decoding ( / receiving / reading / parsing) by the first STA at least a signal field (SIG) of a preamble part of the PPDU. In an embodiment, the SIG comprises a universal SIG (U-SIG), an ultra-high reliable (UHR) SIG, an extremely high throughput (EHT) SIG, a high efficiency (HE) SIG-A / B, a very high throughput (VHT) SIG-A / B, or a high throughput (HT) SIG. In another embodiment, the decoding ( / receiving / reading / parsing) of the part of the PPDU being received by the first STA comprises decoding ( / receiving / reading / parsing) by the first STA at least a first medium access control (MAC) protocol data unit (MPDU) of the PPDU.

[0218] 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.

[0219] Example process 2100 may be performed by a first STA, such as STA 1404 or STA 1902, for example. As shown in FIG. 21, example process 2100 may include steps 2102, 2104, and 2106.

[0220] Step 2102 includes detecting, by the STA and via a primary channel, an OBSS PPDU.

[0221] Step 2104 includes, after detecting the OBSS PPDU, switching, by first STA, from the primary channel to an NPCA primary channel based on a first NPCA switching mode used by the first STA.

[0222] Step 2106 includes receiving, by the first STA from a second STA, a first frame via a bandwidth comprising the NPCA primary channel. The second STA may comprise an AP STA or a non-AP STA. In an embodiment, the second STA may belong to the same BSS as the first STA. In an embodiment, where the first STA comprises a non-AP STA and the second STA comprises an AP STA, the first STA may be associated with the second STA. In an embodiment, a transmission time of the first frame is based on the first NPCA switching mode used by the first STA.

[0223] In an embodiment, the first frame comprises an initial control frame (ICF), a request-to-send (RTS) frame, a multi-user (MU)-RTS frame, a buffer status report poll (BSRP) trigger frame, a block ack request (BAR) frame, a clear-to-send (CTS) frame, a block ack (BA) frame, an acknowledgment (Ack) frame, a buffer status report (BSR) frame, an initial control response frame (ICR), a control frame, a management frame, or an action frame.

[0224] In an embodiment, process 2100 may further comprise receiving, by the first STA from the second STA, a second frame indicating a second NPCA switching mode used by the second STA. The second frame may comprise a beacon frame, a fast initial link setup (FILS) discovery frame, a short beacon frame, a traffic indication map (TIM) broadcast frame, a broadcast frame, or an announcement frame.

[0225] In an embodiment, process 2100 may further comprise transmitting, by the first STA to the second STA, a third frame indicating the first NPCA switching mode. In an embodiment, the third frame comprises a probe request frame, an association request frame, a reassociation request frame, a request frame, 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 third frame comprises a capability element that indicates one or more NPCA switching modes supported by the first STA. In an embodiment, the third frame comprises an operation mode field indicating the first NPCA switching mode being used by the first STA.

[0226] In an embodiment, process 2100 may further comprise, in response to the third frame, receiving, by the first STA from the second STA, a fourth frame indicating the second NPCA switching mode used by the second STA. In an embodiment, the fourth frame comprises a probe response frame, an association response frame, a reassociation response frame, a response frame, 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 capability element that indicates one or more NPCA switching modes supported by the second STA. In an embodiment, the fourth frame comprises an operation mode field indicating the second NPCA switching mode being used by the second STA.

[0227] In an embodiment, the first NPCA switching mode indicates a first time at which the first STA switches from the primary channel to the NPCA primary channel after detecting a first OBSS PPDU on the primary channel. The first NPCA switching mode may correspond to Mode 1 or Mode 2 as described above.

[0228] In an embodiment, the first time occurs after the first STA decodes a signal (SIG) field of the first OBSS PPDU. In an embodiment, where the first OBSS PPDU comprises an extremely high throughput (EHT) PPDU, an ultra-high reliability (UHR) PPDU, or a UHR+ PPDU, the SIG field comprises a universal SIG (U-SIG) field of the first OBSS PPDU. In an embodiment, where the first OBSS PPDU comprises a high efficiency (HE) PPDU, the SIG field comprises an HE- SIG-A field of the first OBSS PPDU. In an embodiment, where the first OBSS PPDU comprises a very high throughput (VHT) PPDU, the SIG field comprises a VHT-SIG-A field of the first OBSS PPDU.

[0229] In another embodiment, the first time occurs after the first STA decodes a first medium access control (MAC) protocol data unit (MPDU) of the first OBSS PPDU. The first OBSS PPDU may comprise a high throughput (HT) PPDU, a very high throughput (VHT) PPDU, a high efficiency (HE) PPDU, an extremely high throughput (EHT) PPDU, an ultra-high reliability (UHR) PPDU, or a UHR+ PPDU.

[0230] In an embodiment, the second NPCA switching mode indicates a second time at which the second STA switches from the primary channel to the NPCA primary channel after detecting a second OBSS PPDU on the primary channel. The second NPCA switching mode may correspond to Mode 1 or Mode 2 as described above.

[0231] In an embodiment, the second time occurs after the second STA decodes a signal (SIG) field of the second OBSS PPDU. In an embodiment, where the second OBSS PPDU comprises an extremely high throughput (EHT) PPDU, an ultra-high reliability (UHR) PPDU, or a UHR+ PPDU, the SIG field comprises a universal SIG (U-SIG) field of the second OBSS PPDU. In an embodiment, where the second OBSS PPDU comprises a high efficiency (HE) PPDU, the SIG field comprises an HE-SIG-A field of the second OBSS PPDU. In an embodiment, where the second OBSS PPDU comprises a very high throughput (VHT) PPDU, the SIG field comprises a VHT-SIG-A field of the second OBSS PPDU.

[0232] In another embodiment, the second time occurs after the second STA decodes a first medium access control (MAC) protocol data unit (MPDU) of the second OBSS PPDU. The second OBSS PPDU may comprise a high throughput (HT) PPDU, a very high throughput (VHT) PPDU, a high efficiency (HE) PPDU, an extremely high throughput (EHT) PPDU, an ultra-high reliability (UHR) PPDU, or a UHR+ PPDU.

[0233] The first OBSS PPDU may be the same as the second OBSS PPDU. That is, the first STA and the second STA may detect the same PPDU as an OBSS PPDU. On detecting the OBSS PPDU, the first STA may switch at the first time after detecting the OBSS PPDU and the second STA may switch at the second time after detecting the OBSS PPDU.

[0234] In an embodiment, process 2100 may further comprise transmitting, by the first STA to the second STA, a fifth frame in response to the first frame. In an embodiment, the fifth frame comprises a clear-to-send (CTS) frame, a BlockAck (BA) frame, an acknowledgment (Ack) frame, a buffer status report (BSR) frame, an initial control response frame (ICR), a control frame, a management frame, or an action frame.

[0235] In an embodiment, process 2100 may further comprise receiving, by the first STA from the second STA, a sixth frame. In an embodiment, receiving the sixth frame is after or in response to transmitting the fifth frame. In an embodiment, the sixth frame comprises a data frame, a management frame, or an action frame.

[0236] In an embodiment, process 2100 may further comprise transmitting, by the first STA to the second STA, a seventh frame in response to the sixth frame. In an embodiment, the seventh frame comprises an immediate response frame.

[0237] In an embodiment, process 2100 may further comprise switching, by the first STA, from the NPCA primary channel to the primary channel before an end of the OBSS PPDU.

[0238] In an embodiment, the first time at which the first STA switches to the NPCA primary channel after detecting an OBSS PPDU on the primary channel is different from the second time at which the first STA switches to the NPCA primary channel after detecting the OBSS PPDU on the primary channel. In an embodiment, where the first time is different than the second time, the transmission time of the first frame is based on the first time.

[0239] In an embodiment, where the first time is earlier than the second time, receiving the first frame may comprise receiving the first frame after an end of a first time period from the second time. The first time period may be configured based on a switching delay of the first STA to switch from the primary channel to the NPCA primary channel.

[0240] In an embodiment, process 2100 may further comprise transmitting, by the first STA to the second STA, an eighth frame during the first time period. The eighth frame may comprise a control frame, a data frame, a management frame, or an action frame. In an embodiment, process 2100 may further comprise, in response to the eighth frame, receiving, by the first STA from the second STA, an immediate response frame.

[0241] In an embodiment, process 2100 may further comprise, after the immediate response frame, receiving, by the first STA from the second STA, a ninth frame. In an embodiment, the ninth frame may be the same as the sixth frame. In an embodiment, process 2100 may further comprise, in response to the ninth frame, transmitting, by the first STA to the second STA, a tenth frame. In an embodiment, the tenth frame may be the same as the seventh frame.

[0242] In an embodiment, the fourth frame comprise a recommendation by the second STA to the first STA to use an NPCA switching mode as the first NPCA switching mode. In an embodiment, process 2100 may further comprise transmitting, by the first STA to the second STA, an eleventh frame in response to the fourth frame. In an embodiment, the eleventh frame indicates acceptance or rejection of the first NPCA switching mode by the second STA.

[0243] In an embodiment, the first NPCA switching mode and the second NPCA switching mode may be the same. In an embodiment, where the first NPCA switching mode and the second NPCA switching mode are the same, process 2100 may further comprise receiving, by the first STA from the second STA, a twelfth frame indicating an operation mode change by the second STA from the second NPCA switching mode to a third NPCA switching mode different than the second NPCA switching mode. In an embodiment, the twelfth frame comprises a control frame, a management, an action frame, a QoS null frame, or a QoS data frame. In an embodiment, process 2100 may further comprise, in response to the twelfth frame, transmitting, by the first STA to the second STA, a thirteenth frame indicating acceptance or rejection of the third NPCA switching mode. In an embodiment, the thirteenth frame comprises a control frame, a management, an action frame, a QoS null frame, or a QoS data frame.

[0244] In another embodiment, where the first NPCA switching mode and the second NPCA switching mode are the same, process 2100 may further comprise transmitting, by the first STA to the second STA, a fourteenth frame indicating an operation mode change by the first STA from the first NPCA switching mode to a fourth NPCA switching mode different than the first NPCA switching mode. In an embodiment, the fourteenth frame comprises a control frame, a management, an action frame, a QoS null frame, or a QoS data frame. In an embodiment, process 2100 may further comprise, in response to the fourteenth frame, receiving, by the first STA from the second STA, a fifteenth frame indicating acceptance or rejection of the fourth NPCA switching mode. In an embodiment, the fifteenth frame comprises a control frame, a management, an action frame, a QoS null frame, or a QoS data frame.

[0245] In an embodiment, the detecting of the OBSS PPDU in step 2102 comprises determining by the first STA that a PPDU being received by the first STA is transmitted by a station belonging to an OBSS before receiving the PPDU fully.

[0246] In an embodiment, the detecting of the OBSS PPDU in step 2102 comprises decoding ( / receiving / reading / parsing) by the first STA a part of a PPDU being received by the first STA to determine if the PPDU is an inter-BSS PPDU. In an embodiment, the decoding ( / receiving / reading / parsing) of the part of the PPDU being received by the first STA comprises decoding ( / receiving / reading / parsing) by the first STA at least a signal field (SIG) of a preamble part of the PPDU. In an embodiment, the SIG comprises a universal SIG (U-SIG), an ultra-high reliable (UHR) SIG, an extremely high throughput (EHT) SIG, a high efficiency (HE) SIG-A / B, a very high throughput (VHT) SIG-A / B, or a high throughput (HT) SIG. In another embodiment, the decoding ( / receiving / reading / parsing) of the part of the PPDU being received by the first STA comprises decoding ( / receiving / reading / parsing) by the first STA at least a first medium access control (MAC) protocol data unit (MPDU) of the PPDU.

[0247] FIG. 22 shows an example 2200 that illustrates an example NPCA operation according to embodiment. Example 2200 is provided for the purpose of illustration only and is not limiting of embodiments. In example 2200, STA 1402 may be configured to switch from the PCH to the NPCA PCH after receiving a SIG field of an OBSS PPDU, if a remaining duration of the OBSS PPDU is greater than an NPCA switching duration threshold. Otherwise, if the remaining duration of the OBSS PPDU after receiving the SIG field of the OBSS PPDU is less than or equal to NPCA switching duration threshold, STA 1402 may not switch from the PCH to the NPCA PCH. In example 2200, after receiving a SIG field of OBSS PPDU 2202, a remaining duration of OBSS PPDU 2202 is larger than (or exceeds) an NPCA switching duration threshold 2204. Thus, STA 1402 switches from the PCH to NPCA PCH after receiving the SIG field of OBSS PPDU 2202. After switching to NPCA PCH, STA 1402 may exchange DL / UL frames with other STA.

[0248] FIG. 23 shows an example 2300 that illustrates another example NPCA operation according to embodiment. Example 2300 is provided for the purpose of illustration only and is not limiting of embodiments. In example 2300, STA 1402 may be configured to switch from the PCH to the NPCA PCH after receiving a first MPDU (e.g., MPDU 1) of an OBSS PPDU 2302. In another embodiment (not shown in FIG. 23), STA 1402 may switch to from the PCH to the NPCA PCH after receiving a MAC header of the first MPDU of OBSS PPDU 2302. In a further embodiment (not shown in FIG. 23), STA 1402 may switch from the PCH to the NPCA PCH after detecting an OBSS frame in a MAC header of the first MPDU of OBSS PPDU 2302. In an example, detecting an OBSS frame in the MAC header of the first MPDU of OBSS PPDU 2302 comprises receiving one or more fields (e.g., one or more of Frame Control field, Duration / ID field, Address 1, Address 2, Address 3, and Address 4) of the MAC header of the first MPDU of OBSS PPDU 2302. After switching to NPCA PCH, STA 1402 may exchange DL / UL frames with other STA.

Claims

CLAIMS:

1. A method comprising: receiving, by an access point (AP) from a first station (STA), a first frame indicating a first nonprimary channel access (NPCA) switching mode used by the first STA, wherein the first NPCA switching mode indicates a first time at which the first STA switches from a primary channel to an NPCA primary channel after detecting a first overlapping basic service set (OBSS) physical layer protocol data unit (PPDU); transmitting, by the AP to the first STA, a second frame indicating a second NPCA switching mode used by the AP, wherein the second NPCA switching mode indicates a second time at which the AP switches from the primary channel to the NPCA primary channel after detecting a second OBSS PPDU; detecting, by the AP and via the primary channel, a third OBSS PPDU; after detecting the third OBSS PPDU, switching, by AP, from the primary channel to the NPCA primary channel based on the second NPCA switching mode; and transmitting, by the AP to the first STA, an initial control frame (ICF) via a bandwidth comprising the NPCA primary channel, wherein a transmission time of the ICF is based on the first NPCA switching mode.

2. A method comprising: transmitting, by a first station (STA) to an access point (AP), a first frame indicating a first nonprimary channel access (NPCA) switching mode used by the first STA, wherein the first NPCA switching mode indicates a first time at which the first STA switches from a primary channel to an NPCA primary channel after detecting a first overlapping basic service set (OBSS) physical layer protocol data unit (PPDU); receiving, by the first STA from the AP, a second frame indicating a second NPCA switching mode used by the AP, wherein the second NPCA switching mode indicates a second time at which the AP switches from the primary channel to the NPCA primary channel after detecting a second OBSS PPDU; after detecting the third OBSS PPDU, switching, by the first STA from the primary channel to the NPCA primary channel based on the first NPCA switching mode; anddetecting, by the first STA and via the primary channel, a third OBSS PPDU; receiving, by the first STA from the AP, an initial control frame (ICF) via a bandwidth comprising the NPCA primary channel, wherein a transmission time of the ICF is based on the first NPCA switching mode.

3. A method comprising: detecting, by a first station (STA) and via a primary channel, an overlapping basic service set (OBSS) physical layer protocol data unit (PPDU); after detecting the OBSS PPDU, switching, by first STA, from the primary channel to a nonprimary channel access (NPCA) primary channel based on a first NPCA switching mode used by the first STA; and transmitting, by the first STA to a second STA, a first frame via a bandwidth comprising the NPCA primary channel, wherein a transmission time of the first frame is based on a second NPCA switching mode used by the second STA.

4. A method comprising: detecting, by a first station (STA) and via a primary channel, an overlapping basic service set (OBSS) physical layer protocol data unit (PPDU); after detecting the OBSS PPDU, switching, by the first STA, from the primary channel to a nonprimary channel access (NPCA) primary channel based on a first NPCA switching mode used by the first STA; and receiving, by the first STA from a second STA, a first frame via a bandwidth comprising the NPCA primary channel, wherein a transmission time of the first frame is based on the first NPCA switching mode.

5. The method of claim 3 or 4 wherein the first frame comprises an initial control frame (ICF), a request-to-send (RTS) frame, a multi-user (MU)-RTS frame, a buffer status report poll (BSRP) trigger frame, a block ack request (BAR) frame, a clear-to-send (CTS) frame, a block ack (BA) frame, an acknowledgment (Ack) frame, a buffer status report (BSR) frame, an initial control response frame (ICR), a control frame, a management frame, or an action frame.

6. The method of any of claims 3 - 5, further comprising receiving, by the first STA from the second STA, a second frame indicating a second NPCA switching mode used by the second STA.

7. The method of claim 6, wherein the second frame comprises a beacon frame, a fast initial link setup (FILS) discovery frame, a short beacon frame, a traffic indication map (TIM) broadcast frame, a broadcast frame, or an announcement frame.

8. The method of any of claims 3 - 7, further comprising: transmitting, by the first STA to the second STA, a third frame indicating the first NPCA switching mode; and in response to the third frame, receiving, by the first STA from the second STA, a fourth frame indicating the second NPCA switching mode.

9. The method of claim 8, wherein the third frame comprises a probe request frame, an association request frame, a reassociation request frame, a request frame, a management frame, an action frame, a control frame, a quality of service (QoS) null frame, or a QoS data frame.

10. The method of any of claims 8 - 9, wherein the third frame comprises a capability element that indicates one or more NPCA switching modes supported by the first STA.

11. The method of any of claims 8 - 10, wherein the third frame comprises an operation mode field indicating the first NPCA switching mode being used by the first STA.

12. The method of any of claims 8 - 11, wherein the fourth frame comprises a probe response frame, an association response frame, a reassociation response frame, a response frame, a management frame, an action frame, a control frame, a quality of service (QoS) null frame, or a QoS data frame.

13. The method of any of claims 8 - 12, wherein the fourth frame comprises a capability element that indicates one or more NPCA switching modes supported by the second STA.

14. The method of any of claims 8 - 13, wherein the fourth frame comprises an operation mode field indicating a second NPCA switching mode being used by the second STA.

15. The method of claims 3 - 14, wherein the first NPCA switching mode indicates a first time at which the first STA switches from the primary channel to the NPCA primary channel after detecting a first OBSS PPDU.

16. The method of claim 15, wherein the first time occurs after the first STA decodes a signal (SIG) field of the first OBSS PPDU.

17. The method of claim 16, wherein the first OBSS PPDU comprises an extremely high throughput (EHT) PPDU, an ultra-high reliability (UHR) PPDU, or a UHR+ PPDU, and wherein the SIG field comprises a universal SIG (U-SIG) field of the first OBSS PPDU.

18. The method of claim 16, wherein the first OBSS PPDU comprises a high efficiency (HE) or very-high throughput (VHT) PPDU, and wherein the SIG field comprises an HE-SIG-A or VHT-SIG-A field of the first OBSS PPDU.

19. The method of claim 15, wherein the first time occurs after the first STA decodes a first medium access control (MAC) protocol data unit (MPDU) of the first OBSS PPDU.

20. The method of claim 19, wherein the first PPDU comprises a high throughput (HT) PPDU, a very high throughput (VHT) PPDU, a high efficiency (HE) PPDU, an extremely high throughput (EHT) PPDU, an ultra-high reliability (UHR) PPDU, or a UHR+ PPDU.

21. The method of any of claims 15 - 20, wherein the second NPCA switching mode indicates a second time at which the second STA switches from the primary channel to the NPCA primary channel after detecting a second OBSS PPDU.

22. The method of claim 21, wherein the second time occurs after the second STA decodes a signal (SIG) field of the second OBSS PPDU.

23. The method of claim 22, wherein the first OBSS PPDU comprises an extremely high throughput (EHT) PPDU, an ultra-high reliability (UHR) PPDU, or a UHR+ PPDU, and wherein the SIG field comprises a universal SIG (U-SIG) of the second OBSS PPDU.

24. The method of claim 22, wherein the first OBSS PPDU comprises a high efficiency (HE) PPDU, and wherein the SIG field comprises an HE-SIG-A field of the second OBSS PPDU.

25. The method of claim 22, wherein the first OBSS PPDU comprises a very high throughput (VHT) PPDU, and wherein the SIG field comprises a VHT-SIG-A field of the second OBSS PPDU.

26. The method of claim 21, wherein the second time occurs after the second STA decodes a first medium access control (MAC) protocol data unit (MPDU) of the second OBSS PPDU.

27. The method of claim 26, wherein the second OBSS PPDU comprises a high throughput (HT) PPDU, a very high throughput (VHT) PPDU, a high efficiency (HE) PPDU, an extremely high throughput (EHT) PPDU, an ultra-high reliability (UHR) PPDU, or a UHR+ PPDU.

28. The method of any of claims 21 - 27, wherein the first OBSS PPDU is same as the second OBSS PPDU.

29. The method of any of claims 3 - 28, further comprising: transmitting, by first STA to the second STA, a fifth frame in response to the first frame; receiving, by the first STA from the second STA, a sixth frame; and transmitting, by the first STA to second STA, a seventh frame in response to the sixth frame.

30. The method of claim 29, wherein the fifth frame comprises a clear-to-send (CTS) frame, a BlockAck (BA) frame, an acknowledgment (Ack) frame, a buffer status report (BSR) frame, an initial control response frame (ICR), a control frame, a management frame, or an action frame.

31. The method of any of claims 29 - 30, wherein the sixth frame comprises a data frame, a management frame, or an action frame.

32. The method of any of claims 29 - 31, wherein the seventh frame comprises an immediate response frame.

33. The method of any of claims 3 - 32, further comprising switching, by the first STA, from the NPCA primary channel to the primary channel before an end of the OBSS PPDU.

34. The method of any of claims 31 - 33, wherein the first time is different from the second time.

35. The method of claim 34, wherein the transmission time of the first frame is based on the first time.

36. The method of claim 35, wherein the first time is later than the second time, and wherein receiving the first frame comprises receiving the first frame after an end of a first time period from the second time.

37. The method of claim 36, wherein the first time is earlier than the second time, and wherein transmitting the first frame comprises transmitting the first frame after an end of a first time period from the first time.

38. The method of claim 37, wherein the first time period is configured based on a switching delay of the first STA to switch from the primary channel to the NPCA primary channel.

39. The method of claim 35, wherein the first time is later than the second time, the method further comprising:transmitting, by the first STA to the second STA and during a first time period, an eighth frame; and in response to the eighth frame, receiving, by the first STA from the second STA, an immediate response frame.

40. The method of claim 39, wherein the eighth frame comprises a control frame, a data frame, a management frame, or an action frame.

41. The method of any of claims 39 - 40, further comprising: after the immediate response frame, receiving, by the first STA from the second STA, a ninth frame; and in response to the ninth frame, transmitting, by the first STA to the second STA, a tenth frame.

42. The method of claim 8, wherein the first NPCA switch mode is recommended / preferred / requested by the second STA for use by the first STA.

43. The method of claim 40, transmitting, by the first STA to the second STA, an eleventh frame in response to the fourth frame.

44. The method of claim 43, wherein the eleventh frame indicates acceptance or rejection of the second NPCA switching mode.

45. The method of any of claims 3 - 44, wherein the first NPCA switching mode and the second NPCA switching mode are the same, the method further comprising: receiving, by the first STA from the second STA, a twelfth frame indicating an operation mode change by the second STA from the second NPCA switching mode to a third NPCA switching mode different than the second NPCA switching mode; and in response to the twelfth frame, transmitting, by first STA to the second STA, a thirteenth frame indicating acceptance or rejection of the third NPCA switching mode.

46. The method of claim 45, wherein the twelfth frame comprises a control frame, a management, an action frame, a QoS null frame, or a QoS data frame.

47. The method of any of claims 45 - 46, wherein the thirteenth frame comprises a control frame, a management, an action frame, a QoS null frame, or a QoS data frame.

48. The method of any of claims 3 - 47, wherein the first NPCA switching mode and the second NPCA switching mode are the same, the method further comprising:transmitting, by first STA to the second STA, a fourteenth frame indicating an operation mode change by the first STA from the first NPCA switching mode to a fourth NPCA switching mode different than the first NPCA switching mode; and in response to the fourteenth frame, receiving, by the first STA from the second STA, a fifteenth frame indicating acceptance or rejection of the fourth NPCA switching.

49. The method of claim 48, wherein the fourteenth frame comprises a control frame, a management, an action frame, a QoS null frame, or a QoS data frame.

50. The method of any of claims 48 - 49, wherein the fifteenth frame comprises a control frame, a management, an action frame, a QoS null frame, or a QoS data frame.

51. The method of any of claims 1 - 50, wherein the detecting of the OBSS PPDU comprises determining by the first STA that a PPDU being received by the STA is transmitted by a station belonging to an OBSS before receiving the PPDU fully.

52. The method of any of claims 1 - 51, wherein the detecting of the OBSS PPDU comprises that decoding ( / receiving / reading / parsing) a part of a PPDU being received by the STA to determine if the PPDU is an inter-BSS PPDU.

53. The method of claim 52, wherein the decoding ( / receiving / reading / parsing) of the part of the PPDU being received by the STA comprises that decoding ( / receiving / reading / parsing) by the STA at least a signal field (SIG) of a preamble part of the PPDU.

54. The method of claim 53, wherein the SIG comprises a universal SIG (U-SIG), an ultra- high reliable (UHR) SIG, an extremely high throughput (EHT) SIG, a high efficiency (HE) SIG- A / B, a very high throughput (VHT) SIG-A / B, or a high throughput (HT) SIG.

55. The method of claim 54, wherein the decoding ( / receiving / reading / parsing) of the part of the PPDU being received by the STA comprises decoding ( / receiving / reading / parsing) by the STA at least a first medium access control (MAC) protocol data unit (MPDU) of the PPDU.

56. The method of any of claims 3 - 55, wherein the first STA comprises a non-access point (non-AP) STA.

57. The method of any of claims 3 - 56, wherein the second STA comprises an access point (AP) STA.

58. The method of any of claims 3 - 58, further comprising transmitting, by the first STA to a third STA, a frame during the first time period.

59. The method of any of claims 1 - 58, further comprising transmitting, by the first STA, a second frame indicating the first NPCA switching mode.

60. The method of claim 58, wherein the third STA is associated with the first STA.

61. The method of any of claims 1 - 60 wherein the transmitting of the first frame after the end of the first time period is based on not receiving an eighth frame from the second STA during the first time period.

62. The method of any of claims 61, wherein the first STA does not transmit to the second STA the first frame based on receiving the eighth frame.

63. A computer program product, storable on a computer-readable medium and arranged to, when run on a computer, execute the method of any preceding claim.

64. An access point (AP) comprising: a processor and a transceiver, the processor being arranged to cause the AP to: receive, from a first station (STA), a first frame indicating a first non-primary channel access (NPCA) switching mode used by the first STA, wherein the first NPCA switching mode indicates a first time at which the first STA switches from a primary channel to an NPCA primary channel after detecting a first overlapping basic service set (OBSS) physical layer protocol data unit (PPDU); transmit to the first STA, a second frame indicating a second NPCA switching mode used by the AP, wherein the second NPCA switching mode indicates a second time at which the AP switches from the primary channel to the NPCA primary channel after detecting a second OBSS PPDU; detect, via the primary channel, a third OBSS PPDU; after detecting the third OBSS PPDU, switching from the primary channel to the NPCA primary channel based on the second NPCA switching mode; and transmit, to the first STA, an initial control frame (ICF) via a bandwidth comprising the NPCA primary channel, wherein a transmission time of the ICF is based on the first NPCA switching mode.

65. A station (STA), comprising a processor and a transceiver, the processor being arranged to cause the STA to: transmit to an access point (AP), a first frame indicating a first non-primary channel access (NPCA) switching mode used by the first STA, wherein the first NPCA switching mode indicates a first time at which the first STA switches from a primary channel to an NPCA primary channel after detecting a first overlapping basic service set (OBSS) physical layer protocol data unit (PPDU); receive from the AP, a second frame indicating a second NPCA switching mode used by the AP, wherein the second NPCA switching mode indicates a second time at which the AP switches from the primary channel to the NPCA primary channel after detecting a second OBSS PPDU; after detecting the third OBSS PPDU, switch from the primary channel to the NPCA primary channel based on the first NPCA switching mode; and detect, via the primary channel, a third OBSS PPDU; receive, by the first STA from the AP, an initial control frame (ICF) via a bandwidth comprising the NPCA primary channel, wherein a transmission time of the ICF is based on the first NPCA switching mode.

66. A device arranged to be used in a first station (STA), the device comprising a processor, the processor being arranged cause the STA to: detect, via a primary channel, an overlapping basic service set (OBSS) physical layer protocol data unit (PPDU); after detecting the OBSS PPDU, switch from the primary channel to a non-primary channel access (NPCA) primary channel based on a first NPCA switching mode used by the first STA; and transmit to a second STA, a first frame via a bandwidth comprising the NPCA primary channel, wherein a transmission time of the first frame is based on a second NPCA switching mode used by the second STA.

67. A device arranged to be used in a first station (STA), the device comprising a processor, the processor being arranged to cause the STA to: detect via a primary channel, an overlapping basic service set (OBSS) physical layer protocol data unit (PPDU);after detecting the OBSS PPDU, switch from the primary channel to a non-primary channel access (NPCA) primary channel based on a first NPCA switching mode used by the first STA; and receive from a second STA, a first frame via a bandwidth comprising the NPCA primary channel, wherein a transmission time of the first frame is based on the first NPCA switching mode.

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