Random access methods for non-primary channel access

Abstract

A station (STA) receives, from an access point (AP) and via a primary channel (PCH), a first trigger frame indicating a first random access resource unit (RA-RU). The STA decrements a first orthogonal frequency division multiple access (OFDMA) backoff (OBO) counter for the PCH. The STA determines that a physical protocol data unit (PPDU) being received via the PCH comprises an inter-basic service set (BSS) PPDU. Based on the determining, the STA switches from the PCH to a non-primary channel access (NPCA) PCH. The STA initializes a second OBO counter for the NPCA PCH. In response to a second trigger frame, indicating a second RA-RU and received via the NPCA PCH, the STA maintains a value of the first OBO counter and decrements the second OBO counter.

Description

TITLERandom Access Methods for Non-Primary Channel AccessCROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims the benefit of U.S. Provisional Application No. 63 / 711,923, filed October 25, 2024, which is hereby incorporated by reference in its entirety.BRIEF DESCRIPTION OF THE DRAWINGS

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

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

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

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

[0006] FIG. 4 illustrates an example of a Quality of Service (QoS) null frame indicating buffer status information.

[0007] FIG. 5 illustrates an example format of a physical layer (PHY) protocol data unit (PPDU).

[0008] FIG. 6 illustrates an example that includes buffer status reporting by STAs, scheduling by an AP of uplink multi-user (MU) transmissions, and transmission of scheduled uplink transmissions by the STAs.

[0009] FIG. 7 illustrates an example of Uplink Orthogonal Frequency Division Multiple Access (OFDMA) Random Access (UORA) operation.

[0010] FIG. 8 illustrates an example UORA Parameter Set element.

[0011] FIG. 9 illustrates an example trigger frame that includes signaling to allow or disallow reducing of a m-OBO counter based on indicated RA-RUs.

[0012] FIG. 10 is an example that illustrates non-primary channel access (NPCA) operation.

[0013] FIG. 11 illustrates virtual and physical carrier sense (CS) functions associated with primary and secondary channels for NPCA operation and non-NPCA operation.

[0014] FIG. 12 shows an example that illustrates an NPCA operation.

[0015] FIG. 13 illustrates an example that highlights a potential problem that may arise using a trigger based NPCA operation.

[0016] FIG. 14 illustrates an example operation according to an embodiment.

[0017] FIG. 15 illustrates an example that highlights a further potential problem that may arise for a trigger based NPCA operation using UORA.

[0018] FIG. 16 illustrates a further example operation according to an embodiment.

[0019] FIG. 17 illustrates another example operation according to an embodiment.

[0020] FIG. 18 illustrates an additional example operation according to an embodiment.

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

[0022] FIG. 20 illustrates a further example process according to an embodiment.DETAILED DESCRIPTION

[0023] 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.

[0024] 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.

[0025] 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.

[0026] 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.

[0027] 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.

[0028] In this disclosure, parameters (or equally called, fields, or Information elements: IBs) may comprise one or more information objects, and an information object may comprise one or more other objects. For example, if parameter (IE) N comprises parameter (IE) M, and parameter (IE) M comprises parameter (IE) K, and parameter (IE) K comprises parameter (information element) J. Then, for example, N comprises K, and N comprises J. In an example embodiment, when one or more messages / frames comprise a plurality of parameters, it implies that a parameter in the plurality of parameters is in at least one of the one or more messages / frames but does not have to be in each of the one or more messages / frames.

[0029] 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.

[0030] 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.

[0031] FIG. 1 illustrates example wireless communication networks in which embodiments of the present disclosure may be implemented.

[0032] 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.

[0033] 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.

[0034] 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).

[0035] 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.

[0036] 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 aplurality 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).

[0037] 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.

[0038] 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.

[0039] 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.

[0040] A frequency band may include one or more sub-bands or frequency channels. For example, PPDUs conforming to the IEEE 802.11n, 802.11ac, 802.11ax and / or 802.11be 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 the default channel for a BSS. An AP of the BSS uses the primary channel to transmit management frames, thereby ensuring that all STAs in the BSS (regardless of channel bonding support) can receive the management frames.

[0041] 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.

[0042] 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.

[0043] 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.

[0044] 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.

[0045] 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.

[0046] As shown in FIG. 3, a MAC frame includes a MAC header, a variable length frame body, and a frame check sequence (FCS)

[0047] 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.

[0048] 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.

[0049] 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.

[0050] 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.

[0051] 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.

[0052] 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.

[0053] 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.

[0054] The power management subfield is used to indicate the power management mode of a STA

[0055] 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.

[0056] The protected frame subfield is set to 1 if the frame body field contains information that has been processed by a cryptographic encapsulation algorithm.

[0057] The +HTC subfield indicates that the MAC frame contains an HT control field.

[0058] 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.

[0059] 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 ofthe 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.

[0060] 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 ofthe 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.

[0061] 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.

[0062] 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.

[0063] 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.

[0064] 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.

[0065] FIG. 4 illustrates an example of a Quality of Service (QoS) null frame indicating buffer status information. A QoS null frame refers to a QoS data frame with an empty frame body. A QoS null frame includes a QoS control field and an optional HT control field which may contain a buffer status report (BSR) control subfield. A QoS null frame indicating buffer status information may be transmitted by a STA to an AP.

[0066] The QoS control field may include a traffic identifier (TID) subfield, an ack policy indicator subfield, and a queue size subfield (or a transmission opportunity (TXOP) duration requested subfield).

[0067] The TID subfield identifies the TC or TS of traffic for which a TXOP is being requested, through the setting of the TXOP duration requested or queue size subfield. The encoding of the TID subfield depends on the access policy (e g., Allowed value 0 to 7 for enhanced distributed channel access (EDCA) access policy to identify user priority for either TC or TS).

[0068] The ack policy indicator subfield, together with other information, identifies the acknowledgment policy followed upon delivery of the MPDU (e.g., normal ack, implicit block ack request, no ack, block ack, etc.)

[0069] The queue size subfield is an 8-bit field that indicates the amount of buffered traffic for a given TC or TS at the STA for transmission to the AP identified by the receiver address of the frame containing the subfield. The queue size subfield is present in QoS null frames sent by a STA when bit 4 of the QoS control field is set to 1. The AP may use information contained in the queue size subfield to determine t TXOP duration assigned to the STA or to determine the uplink (UL) resources assigned to the STA.

[0070] In a frame sent by or to a non-High Efficiency (non-HE) STA, the following rules may apply to the queue size value:The queue size value is the approximate total size, rounded up to the nearest multiple of 256 octets and expressed in units of 256 octets, of all MSDUs and A-MSDUs buffered at the STA (excluding the MSDU or A-MSDU contained in the present QoS Data frame) in the delivery queue used for MSDUs and A-MSDUs with TID values equal to the value indicated in the TID subfield of the QoS Control field.A queue size value of 0 is used solely to indicate the absence of any buffered traffic in the queue used for the specified TID.A queue size value of 254 is used for all sizes greater than 64768 octets.A queue size value of 255 is used to indicate an unspecified or unknown size.

[0071] In a frame sent by an HE STA to an HE AP, the following rules may apply to the queue size value.

[0072] The queue size value, QS, is the approximate total size in octets, of all MSDUs and A-MSDUs buffered at the STA (including the MSDUs or A-MSDUs contained in the same PSDU as the frame containing the queue size subfield) in the delivery queue used for MSDUs and A-MSDUs with TID values equal to the value indicated in the TID subfield of the QoS control field.

[0073] The queue size subfield includes a scaling factor subfield in bits B14-B15 of the QoS control field and an unsealed value, UV, in bits B8-B13 of the QoS control field. The scaling factor subfield provides the scaling factor, SF.

[0074] A STA obtains the queue size, QS, from a received QoS control field, which contains a scaling factor, SF, and an unsealed value, UV, as follows:QS =16 *UV, if SF is equal to O;1024 + 256 x W, if SF is equal to 1;17408 + 2048 x UV, if SF is equal to 2;148480 +32768 x UV, if SF is equal to 3 and UV is less than 62;> 2 147328, if SF equal to is 3 and UV is equal to 62;Unspecified or Unknown, if SF is equal to 3 and UV is equal to 63.

[0075] The TXOP duration requested subfield, which may be included instead of the queue size subfield, indicates the duration, in units of 32 microseconds (us), that the sending STA determines it needs for its next TXOP for the specified TID. The TXOP duration requested subfield is set to 0 to indicate that no TXOP is requested for the specified TID in the current service period (SP). The TXOP duration requested subfield is set to a nonzero value to indicate a requested TXOP duration in the range of 32 us to 8160 us in increments of 32 us.

[0076] The HT control field may include a BSR control subfield which may contain buffer status information used for UL MU operation. The BSR control subfield may be formed from an access category index (ACI) bitmap subfield, a delta TID subfield, an ACI high subfield, a scaling factor subfield, a queue size high subfield, and a queue size all subfield of the HT control field.

[0077] The ACI bitmap subfield indicates the access categories for which buffer status is reported (e.g., BO: best effort (AC_BE), B1: background (AC_BK), B2: video (AC_VI), B3: voice (AC_V0), etc.). Each bit of the ACI bitmap subfield is set to 1 to indicate that the buffer status of the corresponding AC is included in the queue size all subfield, and set to 0 otherwise, except that if the ACI bitmap subfield is 0 and the delta TID subfield is 3, then the buffer status of all 8 TIDs is included.

[0078] The delta TID subfield, together with the values of the ACI bitmap subfield, indicate the number of TIDs for which the STA is reporting the buffer status.

[0079] The ACI high subfield indicates the ACI of the AC for which the BSR is indicated in the queue size high subfield. The ACI to AC mapping is defined as ACI value 0 mapping to AC_BE, ACI value 1 mapping to AC_BK, ACI value 2 mapping to AC_VI, and ACI value 3 mapping to AC_V0.

[0080] The scaling factor subfield indicates the unit SF, in octets, of the queue size high and queue size all subfields.

[0081] The queue size high subfield indicates the amount of buffered traffic, in units of SF octets, for the AC identified by the ACI high subfield, that is intended for the STA identified by the receiver address of the frame containing the BSR control subfield.

[0082] The queue size all subfield indicates the amount of buffered traffic, in units of SF octets, for all Acs identified by the ACI Bitmap subfield, that is intended for the STA identified by the receiver address of the frame containing the BSR control subfield.

[0083] The queue size values in the queue size high and queue size all subfields are the total sizes, rounded up to the nearest multiple of SF octets, of all MSDUs and A-MSDUs buffered at the STA (including the MSDUs or A-MSDUs contained in the same PSDU as the frame containing the BSR control subfield) indelivery queues used for MSDUs and A-MSDUs associated with AC(s) that are specified in the ACI high and ACI bitmap subfields, respectively.

[0084] A queue size value of 254 in the queue size high and queue size all subfields indicates that the amount of buffered traffic is greater than 254 x SF octets. A queue size value of 255 in the queue size high and queue size all subfields indicates that the amount of buffered traffic is an unspecified or unknown size. The queue size value of QoS data frames containing fragments may remain constant even if the amount of queued traffic changes as successive fragments are transmitted.

[0085] MAC service provides peer entities with the ability to exchange MSDUs. To support this service, a local MAC uses the underlying PHY-level service to transport the MSDUs to a peer MAC entity. Such asynchronous MSDU transport is performed on a connectionless basis.

[0086] FIG. 5 illustrates an example format of a physical layer (PHY) protocol data unit (PPDU). As shown, the PPDU may include a PHY preamble, a PHY header, a PSDU, and tail and padding bits.

[0087] The PSDU may include one or more MPDUs, such as a QoS data frame, an MMPDU, a MAC control frame, or a QoS null frame. In the case of an MPDU carrying a QoS data frame, the frame body of the MPDU may include a MSDU or an A-MSDU.

[0088] By default, MSDU transport is on a best-effort basis. That is, there is no guarantee that a transmitted MSDU will be delivered successfully. However, the QoS facility uses a traffic identifier (TID) to specify differentiated services on a per-MSDU basis.

[0089] A STA may differentiate MSDU delivery according to designated traffic category (TC) or traffic stream (TS) of individual MSDUs. The MAC sublayer entities determine a user priority (UP) for an MSDU based on a TID value provided with the MSDU. The QoS facility supports eight UP values. The UP values range from 0 to 7 and form an ordered sequence of priorities, with 1 being the lowest value, 7 the highest value, and 0 falling between 2 and 3.

[0090] An MSDU with a particular UP is said to belong to a traffic category with that UP. The UP may be provided with each MSDU at the medium access control service access point (MAC SAP) directly in a UP parameter. An A-MPDU may include MPDUs with different TID values.

[0091] A STA may deliver buffer status reports (BSRs) to assist an AP in allocating UL MU resources. The STA may either implicitly deliver BSRs in the QoS control field or BSR control subfield of any frame transmitted to the AP (unsolicited BSR) or explicitly deliver BSRs in a frame sent to the AP in response to a BSRP Trigger frame (solicited BSR)

[0092] The buffer status reported in the QoS control field includes a queue size value for a given TID. The buffer status reported in the BSR control field includes an ACI bitmap, delta TID, a high priority AC, and two queue sizes.

[0093] A STA may report buffer status to the AP, in the QoS control field, of transmitted QoS null frames and QoS data frames and, in the BSR control subfield (if present), of transmitted QoS null frames, QoS data frames, and management frames as defined below.

[0094] The STA may report the queue size for a given TID in the queue size subfield of the QoS control field of transmitted QoS data frames or QoS null frames; the STA may set the queue size subfield to 255 to indicate an unknown / unspecified queue size for that TID. The STA may aggregate multiple QoS data frames or QoS null frames in an A-MPDU to report the queue size for different TIDs.

[0095] The STA may report buffer status in the BSR control subfield of transmitted frames if the AP has indicated its support for receiving the BSR control subfield.

[0096] A High-Efficiency (HE) STA may report the queue size for a preferred AC, indicated by the ACI high subfield, in the queue size high subfield of the BSR control subfield. The STA may set the queue size high subfield to 255 to indicate an unknown / unspecified queue size forthat AC.

[0097] A HE STA may report the queue size for ACs indicated by the ACI bitmap subfield in the queue size all subfield of the BSR control subfield. The STA may set the queue size all subfield to 255 to indicate an unknown / unspecified BSR for those ACs.

[0098] FIG. 6 illustrates an example 600 that includes buffer status reporting by STAs, scheduling by an AP of uplink multi-user (MU) transmissions, and transmission of scheduled uplink transmissions by the STAs. As shown, the AP may solicit one or more associated STAs (e.g., STA 1 and STA 2) for buffer status by sending a buffer status report poll (BSRP) trigger frame. Upon receiving the BSRP trigger frame, STA 1 and / or STA 2 may each generate a trigger-based (TB) PPDU including a BSR, if the BSRP trigger frame contains, in a User Info field, the 12 LSBs of the STA’s AID.

[0099] STA 1 and / or STA 2 may each report respective BSRs by including in the TB PPDU one or more QoS Data or QoS null frames. The one or more QoS Data or QoS null frames may contain one or more QoS control fields or one or more BSR control subfields.

[0100] As described earlier, a QoS control field may include a queue size subfield for a TID for which the STA has a queue size to report to the AP. For example, as shown in FIG. 6, STA 1 may respond to the BSRP trigger frame from the AP by transmitting an A-MPDU including multiple QoS null frames. The QoS null frames each indicate, in a respective QoS control field, a queue size for a respective TID, e.g. TID 0 and TID 2. Similarly, STA 2 may respond to the BSRP trigger frame by transmitting an MPDU including a QoS null frame, which indicates a queue size for TID 2 in its QoS control field.

[0101] A BSR control subfield may include a queue size all subfield indicating the queue size for the ACs, indicated by the ACI bitmap subfield, for which the STA has a queue size to report to the AP if the AP has indicated its support for receiving the BSR control subfield. The STA sets a delta TID, a scaling factor, an ACI high, and the queue size high subfields of the BSR Control subfield.

[0102] On receiving the BSRs from STA 1 and STA 2, the AP may transmit a basic trigger frame to allocate UL MU resources to STA 1 and STA 2. In response, STA 1 may transmit a TB PPDU containing QoS data frames with TID 0 and TID 2 and STA 2 may transmit a TB PPDU containing one or more QoS data frame(s) with TID. The AP may acknowledge the transmitted TB PPDUs from STA 1 and STA 2 by sending a multi-STA block ack frame.

[0103] FIG. 7 illustrates an example 700 of Uplink Orthogonal Frequency Division Multiple Access (OFDMA) Random Access (UORA) operation. For the purpose of illustration, the example UORA operation is described with reference to an example WLAN environment that includes an AP and a plurality of STAs (STA1, STA2, and STA3). The plurality of STAs may each be associated or not associated with the AP.

[0104] The AP may support UORA operation. As such, the AP may transmit a Basic Trigger frame, a Bandwidth Query Report Poll (BQRP) Trigger frame, or a BSRP Trigger frame that contains one or more resource units (RUs) for random access. A User Info field in a trigger frame whose 12-bit AID subfield is set to 0 indicates an allocation of one or more contiguous random access RUs (RA-RUs) for associated STAs. Similarly, a User Info field in a trigger frame whose 12-bit AID subfield is set to 2045 indicates an allocation of one or more contiguous RA-RUs for unassociated STAs.

[0105] FIG. 8 illustrates an example UORA Parameter Set element 800. An AP may include a UORA Parameter Set element, such as element 800, in management frames that it transmits. As shown in FIG. 8, example UORA Parameter Set element 800 may include an Element ID field, a Length field, an Element ID Extension field, and an OCW range field. Parameter Set element 800 is merely one example of a UORA parameter set element, and any suitable fields and values may be used.

[0106] The Element ID and the Element ID Extension field values may be set to 255 and 37 respectively, thereby uniquely identifying the UORA Parameter Set element from other information elements sent by the AP in management frames.

[0107] The Length field may indicate the number of octets in the element excluding the Element ID and Length fields.

[0108] The OCW Range field may indicate the range of an OFDMA contention window for STAs to initiate random access following transmission of the trigger frame. As shown, the OCW range field may include an EOCWmin subfield, an EOCWmax subfield, and a Reserved subfield.

[0109] The EOCWmin subfield may indicate a minimum value of OCW (OCWmin) for initial TB PPDU transmission using UORA. The OCWmin parameter may be used by a STA either for an initial transmission or following a successful TB PPDU transmission. The OCWmin parameter may be derived as follows: OCWmin = 2AE0CWmin - 1 , where EOCWmin is the value in the EOCWmin subfield. The EOCWmax subfield may indicate a maximum value of OCW (OCWmax) for UORA. The OCWmax parameter may be used by a STA for retransmission attempts of UORA. The OCWmax parameter may be derived usingOCWmax = 2AE0CWmax - 1 , where EOCWmax is the value in the EOCWmax subfield. The Reserved subfield may be used for signaling future features related to the UORA operation and may be set to 0.

[0110] A STA that supports UORA may maintain an internal OCW. OCW may be an integer in the range of OCWmin to OCWmax. A STA may update the OCWmin and OCWmax variables from a UORA Parameter Set element within an interval of time equal to one beacon interval after receiving an updated UORA Parameter Set element carried in a beacon, Probe Response, or (Re)Association Response frame transmitted by its associated AP. An unassociated non-AP STA that has not received a UORA Parameter Set element from the AP with which it intends to communicate may use a default OCWmin of 7 and a default OCWmax of 31.

[0111] A STA that supports UORA may also maintain an internal OFDMA random access backoff (OBO) counter which may be initialized in the range of 0 to OCW. A STA whose TB PPDU transmission sent in an RA-RU indicated by a trigger frame is unsuccessful, may attempt to retransmit the failed PPDU using EDCA or as a response to a trigger frame. If the TB PPDU is not successfully transmitted in the selected RA-RU, then the STA may update its OCW to 2 x OCW + 1 , as long as the updated OCW is less than the value of OCWmax. The STA may then randomly select its OBO counter in the range of 0 and the updated OCW. Once the OCW reaches OCWmax for successive retransmission attempts, the OCW may remain at the value of OCWmax. A STA may update its OCW value under the condition that the updated OCW remains in the range OCWmin to OCWmax obtained from the most recently received UORA Parameter Set element. If the updated OCW becomes greater than OCWmax as a consequence of receiving a modified UORA Parameter Set element, then the STA may set the value of OCW to the new OCWmax value.

[0112] Returning to FIG. 7, in the illustrated UORA operation, the AP may transmit a trigger frame 720 with 3 RA-RUs (RU1 , RU2, and RU3, indicated by the AID value of 0) and a scheduled RU (RU4, indicated by the AID value of 3) assigned to STA3 (which has an AID equal to 3).

[0113] It is assumed, in this example, that STA1 and STA2 have previously initialized their OBO counters to 1 and 6 respectively. Upon receiving the trigger frame 720, STA1 and STA2, which have pending frames for the AP, may decrement their respective OBO counters by the number of eligible RA-RUs indicated in the trigger frame 720 (i.e., three RA-RUs). Once the OBO counter of STA1 decrements to 0 (negative OBO are clipped to 0), STA1 may transmit pending frames (e.g., in a TB PPDU 751) on RU1, which STA1 may randomly select from the eligible set of RA-RUs (i.e., RU1 , RU2, and RU3). For example, a non-AP STA may consider an RU as an eligible RA-RU if it is capable of transmitting a PPDU (e.g., an HE TB PPDU) in that RU according to the parameters indicated in the Common Info field and in the User Info field that allocates the RU (e.g., as discussed below in relation to example trigger frame 900 illustrated in FIG. 9), the non-AP STA is associated with the BSS whose BSSID is a value in a TA field of the trigger frame, and the RA-RU is allocated for associated STAs. As another example, a non-AP STA may consider an RU as an eligible RA-RU if it supports all the transmit parameters indicated in the Common Info field and in the UserInfo field that allocates that RU, the non-AP STA is not associated with the BSS, and the RA-RU is allocated for unassociated STAs. The OBO counter of STA2 decrements to a nonzero value (3). STA2 may maintain the new OBO value (3) until it receives a later trigger frame carrying RA-RUs for associated STAs.

[0114] STA3, which also has pending frames for the AP, may be allocated a dedicated RU (RU4). STA3 thus does not contend for RA-RUs and instead transmits pending frames on RU4 (e.g., in a TB PPDU 752).

[0115] In this example, the TB PPDUs 751 and 752 from STA1 and STA3 contain frames that solicit an immediate response. Hence, the AP transmits a Multi-STA BlockACK frame 770 in response to TB PPDUs 751 and 752. The reception of the Multi-STA BlockACK frame 770 by STA1 and STA3 respectively indicates to STA1 and STA3 that the transmission of TB PPDU 751 and 752 respectively was successful. If no such acknowledgement is received by STA1 or STA3, the respective PPDU transmission is considered unsuccessful.

[0116] After a successful TB PPDU transmission in an RA-RU, a STA may set the value of its OCW to the OCWmin indicated in the latest UORA Parameter Set element from the AP or to the default OCWmin (if a UORA Parameter Set element was not received). The STA may also initialize its OBO counter to an integer value randomly selected from a uniform distribution in the range 0 to OCW.

[0117] FIG. 9 illustrates an example trigger frame that includes signaling to allow or disallow reducing of a m-OBO counter based on indicated RA-RUs. As shown in FIG. 9, example trigger frame 900 includes a Frame Control field, a Duration field, a receive address (RA) field, a transmit address (TA) field, a Common Info field, a User List Info field, a Padding Info field, and an FCS field. The Common Info field and the User List Info field make up the body of the trigger frame.

[0118] The Common Info field may consist of parameters that are common to all users such as the Type of trigger frame and the PPDU bandwidth being triggered.

[0119] The User List Info field may include several User Info Fields which signal assignments of RUs to STAs. A User Info field may include an AID12 subfield, an RU Allocation subfield, a UL FEC Coding Type Subfield, a UL HE-MCS subfield, a UL DCM subfield, an SS Allocation / RA-RU Information subfield, a UL Target Receive Power subfield, a Reserved / ML UORA Disallow subfield, and a Trigger Dependent User info subfield.

[0120] The AID12 subfield may identify the STA to which the User Info field applies and to which an RU is being assigned. An AID12 value between 1 and 2007 may indicate that the RU is being assigned to the STA whose last 12 bits of its AID matches the AID12 value. An AID12 value of 0 may indicate that the indicated contiguous RUs are contiguous RA-RUs assigned for associated STAs. An AID12 value of 2045 may indicate that the indicated contiguous RUs are contiguous RA-RUs assigned for unassociated STAs.

[0121] The RU allocation subfield may identify the size and location of the assigned RU relative to the whole PPDU frequency band. In an example, when the AID12 subfield indicates that the RU is an RA-RU, B39 (of the Reserved / ML UORA Disallow subfield) may be used to signal allowing / disallowing m-OBOcounter reduction based on the indicated number of RA-RUs. For example, B39 having a value equal to 1 may signal that ML UORA is disallowed on the RA-RU indicated by the User Info Field and that a STA MLD may not decrement its m-OBO counter based on the indicated number of RA-RUs. Otherwise, when B39 is equal to 0, ML UORA may be allowed and the STA MLD may decrement its m-OBO counter based on the indicated number of RA-RUs for ML UORA contention.

[0122] In an example, when the AID12 subfield indicates that the RU is an RA-RU, B26 to B31 of the User Info Field signal an RA-RU information subfield which includes 2 further subfields: Number of RA-RU and More RA-RU. The Number of RA-RU subfield may indicate the number of contiguous RUs allocated for UORA. The value of the Number of RA-RU subfield may be equal to the number of contiguous RA-RUs minus 1 . The More RA-RU subfield may be set to 1 to indicate that RA-RUs of the type indicated by the AID12 subfield in the User Info field are allocated in subsequent Trigger frames that are sent until the end of a service period in which the trigger frame carrying the More RA-RU subfield set to 1 is sent. Otherwise, the subfield may be set to 0.

[0123] It is envisioned in future IEEE 802.11 standards that a STA (AP STA or non-AP STA) may access a non-primary channel to communicate with another STA. Such operation may be referred to as non-primary channel access (NPCA) operation. Specifically, in addition to a default primary channel (which is used by all STAs in the BSS and via which the AP transmits management frames), the STA may have one or more secondary channels considered as NPCA primary channels. The STA may transmit or receive on a channel that includes an NPCA primary channel but that does not necessarily include the primary channel (e.g., when the primary channel is unavailable). The STA may maintain a NAV for an NPCA primary channel independent of the NAV associated with the primary channel.

[0124] FIG. 10 shows an example 1000 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. 10, 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. 10. For example, the NPCA primary channel may correspond to SCH1 .

[0125] FIG. 11 shows an example 1100 that illustrates virtual and physical carrier sense (CS) functions associated with primary and secondary channels for NPCA operation and non-NPCA operation. In an implementation, as shown in FIG. 11 , 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 onthe PCH. As such, as shown in FIG. 11, 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 N AV associated with the PCH is zero (and the physical CS function indicates "channel idle” for all channels being used)

[0126] In contrast, as also shown in FIG. 11, 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. 10, 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.

[0127] In implementations, the STA may perform physical and / or virtual CS functions (herein referred to as CS or CCA) on multiple channels (e.g., PCH and NPCA PCH). If the PCH is busy (non-zero NAV or CCA indicates “channel busy”), the STA may use the NPCA PCH for transmission if the NPCA PCH is idle (zero NAV and CCA indicates “channel idle”).

[0128] 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

[0129] FIG. 12 shows an example 1200 that illustrates an NPCA operation. As shown in FIG. 12, example 1200 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).

[0130] Example 1200 may begin with the AP transmitting a frame 1202 on the PCH. Frame 1202 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 1202 may be a management frame, such as a beacon frame, for example.

[0131] Subsequently, while the AP and STA operate on the PCH, transmission of a frame 1204 from an OBSS may begin on the PCH. The AP and the STA may detect frame 1204 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 1204 on the PCH. Frame 1204 may indicate a transmission (of one or more frames including frame 1204) on the PCH. A duration of the transmission on the PCH may be provided by a duration field of frame 1204, a transmission opportunity (TXOP) duration field of an OBSS PPDU comprising frame 1204, 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 (hereinafter, OBSS NAV duration or OBSS TXOP duration).

[0132] 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.

[0133] 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 1202). In example 1200, 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 1206 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 1206 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. 12) on the NPCA PCH.

[0134] FIG. 13 illustrates an example 1300 that highlights a potential problem that may arise using a trigger based NPCA operation. 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 and may operate over a plurality of channels,including a PCH, an NPCA PCH, a first secondary channel (SCH1), and a second secondary channel (SCH2).

[0135] Example 1300 may begin with the AP and STA operating on the PCH. While the AP and STA operate on the PCH, transmission of a frame 1304 from an OBSS may begin on the PCH. The AP and the STA may detect frame 1304 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 1304 on the PCH. Frame 1304 may indicate a transmission (of one or more frames including frame 1304) on the PCH. A duration of the transmission on the PCH may be provided by a duration field of frame 1304, a TXOP duration field of an OBSS PPDU comprising frame 1304, or a length field of the OBSS PPDU. The AP and STA may set their NAVs for the PCH based on the OBSS NAV duration or OBSS TXOP duration.

[0136] 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.

[0137] In an example, the AP and STA may use a trigger based NPCA operation, in which the AP initiates a transmission opportunity in the NPCA PCH for the STA. For example, the AP may transmit a frame 1306 via the NPCA PCH to the STA. Frame 1306 may be an initial control frame (ICF), which may be used in a variety of operations (e.g., dynamic power saving, dynamic subband operation, and device coexistence features). Alternatively, frame 1306 may be a BSRP frame used to poll stations of their uplink transmit buffer. The BSRP frame may, further, be used to poll whether the STA is operating in (i.e. has switched from the PCH to the NPCA PCH) the NPCA PCH. For example, by responding to the BSRP the STA implicitly indicates that the STA is operating in the NPCA PCH.

[0138] The STA may receive frame 1306 from the AP, and may reply with a response frame 1308 to the AP via the NPCA PCH. For example, if frame 1306 is an ICF, the STA may reply with an initial control response (ICR). As another example, if frame 1306 is a BSRP, the STA may reply with a BSR.

[0139] After receiving response frame 1308 from the STA, the AP may transmit a frame 1310 to the STA via the NPCA PCH. For example, frame 1310 may include a data frame. The STA may respond to frame 1310 with a BA frame 1312. Alternatively, or in addition, the AP may share the TXOP to the STA so that the STA may transmit an UL frame (not pictured) to the AP.

[0140] As noted, the trigger based NPCA operation allows an AP to initiate transmission opportunities for STAs (e.g., DL and UL transmit opportunities) in the NPCA PCH. If the AP is associated with multiple STAs, however, the trigger based NPCA operation may require significant time and generate significant overhead. For example, if an AP is associated with a large number of STAs, a long time and a significant overhead may be needed for the AP to poll its associated STAs (e.g., using a BSRP or ICF).

[0141] Embodiments of the present disclosure, as further described below, address the above-described problem associated with existing technologies. For example, performance for trigger based NPCA operations may be improved by, in an embodiment, using a trigger frame identifying RA-RUs for UORA, as discussed above in relation to FIGS. 7-9. In an embodiment, this may reduce a number of trigger frame transmissions (e.g., BSRP or ICF transmissions) from an AP to poll its associated STAs. By allowing the AP to allocate RA-RUs in the NPCA PCH, the AP may not need to poll its associated STAs one by one, which may significantly reduce the overhead (e.g., when there are a large number of associated STAs). In an aspect, a STA switches from a first channel to a second channel. A second orthogonal frequency division multiple access (OFDMA) backoff (OBO) counter is initialized for the second channel. The STA receives, from an AP and via the second channel, a first trigger frame (TF) indicating a first random access resource unit (RA-RU). The STA maintains a value of a first OBO counter for the first channel.

[0142] FIG. 14 illustrates an example operation 1400 according to an embodiment. As shown in FIG. 14, example 1400 includes an AP 1401 and a STA 1402 associated with AP 1401. AP 1401 and STA 1402 may both support NPCA operation and may operate over a plurality of channels, including a PCH, an NPCA PCH, a first secondary channel (SCH1), and a second secondary channel (SCH2).

[0143] Example 1400 may begin with AP 1401 and STA 1402 operating on the PCH. In an embodiment, AP 1401 and STA 1402 operate using UORA for transmission on the PCH, as discussed above in relation to FIGS. 7-9. AP 1401 transmits a frame 1403 to STA 1402. In an embodiment, frame 1403 is a trigger frame. For example, like trigger frame 720 illustrated in FIG. 7, frame 1403 may indicate RA-RUs and scheduled RUs for STAs associated with AP 1401. Frame 1403 may identify a number R of RA-RUs for use by the STAs associated with AP 1401 , including STA 1402. For example, frame 1403 may identify five RA-RUs.

[0144] In example 1400, it is assumed that STA 1402 has previously initialized an OBO counter (e.g., to 10). Upon receiving frame 1403, STA 1402 may decrement its OBO counter by the number of eligible RA-RUs indicated in frame 1403 (e.g., five RA-RUs). Once the OBO counter of STA 1402 decrements to 0 (negative OBO are clipped to 0), STA 1402 may transmit any pending frames (not pictured) on a selected RU (e.g., a randomly selected RU from an eligible set of RA-RUs), depending on the RU allocation by AP 1401 in frame 1403.

[0145] While AP 1401 and STA 1402 operate on the PCH, transmission of a frame 1404 from an OBSS may begin on the PCH. AP 1401 and STA 1402 may detect frame 1404 on the PCH. In an implementation, AP 1401 and STA 1402 may be configured to set a NAV associated with the PCH based on receiving frame 1404 on the PCH. Frame 1404 may indicate a transmission (of one or more frames including frame 1404) on the PCH. A duration of the transmission on the PCH may be provided by a duration field of frame 1404, a TXOP duration field of an OBSS PPDU comprising frame 1404, or a length field of the OBSS PPDU. AP 1401 and STA 1402 may set their NAVs for the PCH based on the OBSS NAV duration or OBSS TXOP duration.

[0146] In accordance with NPCA operation, on receiving an OBSS PPDU and obtaining the OBSS NAV duration, AP 1401 and STA 1402 may be configured to switch to the NPCA PCH for the OBSS NAV duration. AP 1401 and STA 1402 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.

[0147] In an example, AP 1401 and STA 1402 may use trigger based NPCA operation, in which AP 1401 initiates a transmission opportunity in the NPCA PCH for STA 1402. For example, AP 1401 may transmit a frame 1406 via the NPCA PCH to STA 1402. In an embodiment, frame 1406 may comprise a trigger frame indicating RA-RUs for UORA. For example, like frame 1403, frame 1406 may indicate RA-RUs and scheduled RUs for STAs associated with AP 1401. Frame 1406 may be transmitted on the NPCA PCH and may identify a number R of RA-RUs for use by the STAs associated with AP 1401 , including STA 1402, during transmission on the NPCA PCH. For example, frame 1406 may identify five RA-RUs.

[0148] Further, in an example, in addition to indicating RA-RUs, frame 1406 may be an initial control frame (ICF), may be used in a variety of operations (e.g., dynamic power saving, dynamic subband operation and device coexistence features). Alternatively, frame 1406 may be a BSRP frame used to poll stations of their uplink transmit buffer.

[0149] In an embodiment, STA 1402 may use an OBO counter for UORA transmission on the NPCA PCH. For example, STA 1402 may use an existing OBO counter, used for UORA transmission on the PCH (e.g., in response to frame 1403), for UORA transmission on the NPCA PCH (e.g., in response to frame 1406). That is, STA 1402 may use the same OBO counter both for UORA transmission on the PCH and for UORA transmission on the NPCA PCH. In an embodiment, STA 1402 may reinitialize the OBO counter using an existing OCW, used for UORA transmission on the PCH. After receiving frame 1406 identifying five RA-RUs, STA decrements the OBO counter with the number of RA-RUs identified in frame 1406 (e.g., five), as if frame 1406 is being transmitted in the PCH. Once the OBO counter reaches 0, STA 1402 may transmit a frame 1408 to AP 1401 using the NPCA PCH. For example, if frame 1406 is an ICF, STA 1402 may reply with an ICR. As another example, if frame 1406 is a BSRP, STA 1402 may reply with a BSR.

[0150] After receiving frame 1408 from STA 1402 via the NPCA PCH, AP 1401 may transmit a frame 1410 to STA 1402 using the NPCA PCH. For example, frame 1410 may include a data frame. STA 1402 may respond to frame 1410 with a BA frame 1412. Alternatively, or in addition, AP 1401 may share the TXOP to STA 1402 so that STA 1402 may transmit an UL frame (not pictured) to AP 1401 using the NPCA PCH. In an embodiment, using UORA for transmission on the NPCA PCH (e.g., trigger based transmission on the NPCA PCH) may reduce time, and overhead, needed for polling. For example, AP 1401 may allocate a number of RUs as RA-RUs, and any associated STA may transmit their trigger response frame (e.g., ICR or BSR) randomly on one of the allocated RA-RUs.

[0151] After receiving BA frame 1412, STA 1402 may reinitialize the OBO counter if STA 1402 has more frames to transmit to AP 1401. STA 1402 may also reset the OCW to an existing OCWmin parameter usedfor UORA transmissions via the PCH. In another embodiment, e.g., when STA 1402 does not receive BA frame 1412 from AP 1401 (not shown in example 1400), STA 1402 may update the OCW to 2*0CW +1 when the OCW is less than the value of an existing OCWmax parameter used for UORA transmissions via the PCH. Once the OCW reaches OCWmax for successive retransmissions attempts, STA 1402 may set the OCW equal to OCWmax.

[0152] FIG. 15 illustrates an example 1500 that highlights a further potential problem that may arise for a trigger based NPCA operation using UORA. As shown in FIG. 15, example 1500 includes AP 1401 and STA 1402 illustrated in example 1400 in FIG. 14. Like example 1400, in an example STA 1402 may use an OBO counter for UORA transmission on the NPCA PCH. For example, STA 1402 may use an existing OBO counter, used for UORA transmission on the PCH (e.g., in response to frame 1403), for UORA transmission on the NPCA PCH (e.g., in response to frame 1406). This is discussed further, above, in relation to example 1400 illustrated in FIG. 14. As in example 1400, after receiving frame 1406 identifying a number R of RA-RUs, STA 1402 may decrement its OBO counter by R, and once the OBO counter eventually reaches 0, STA 1402 may transmit a frame 1408 (e.g., an ICR or BSR) to AP 1401 using the NPCA PCH. AP 1401 may then transmit a frame 1410 to STA 1402 using the NPCA PCH. STA 1402 may respond to frame 1410 with a BA frame 1412. Alternatively, or in addition, AP 1401 may share the TXOP to STA 1402 so that STA 1402 may transmit an UL frame (not pictured) to AP 1401 using the NPCA PCH.

[0153] When there are many STAs contending on RA-RUs on the PCH, however, and / or when not all STAs have switched to the NPCA PCH, re-using the OBO counter for UORA transmission on the PCH for UORA transmission on the NPCA PCH may be inefficient. As discussed above in relation to FIGS. 7-9, for UORA operation the OFDMA contention window (OCW) may approximately double each time a collision occurs (e.g., according to 0CW=2*0CW+1). The OCW may start with a value OCWmin and may increase up to a value OCWmax (e.g., determined using a UORA Parameter Set element as described above in relation to FIG. 8). When there are many STAs contending for channel access, the OCW increases accordingly. The initial value of the OBO counter also increases accordingly. RA-RUs allocated in the NPCA channel are only available to STAs that switch to the NPCA channel, typically a fraction of all STAs in the PCH. When the OBO counter in the PCH is reused in the NPCA PCH, with decrementing based on the number of allocated RA-RUs, the OBO counter may be too high to allow transmission in the NPCA PCH.

[0154] For example, as illustrated in example 1500, the OBO counter may be set to an initial value of 15 for transmission on the PCH (e.g., due to a large number of contending STAs in the PCH). If the OBO counter for UORA transmission on the PCH is reused for UORA transmission on the NPCA PCH, STA 1402 may not be able to transmit, in response to frame 1406, due to the OBO counter being non-zero. This may reduce the efficiency of using UORA for trigger based NPCA operation.

[0155] Further embodiments of the present disclosure, as further described below, address this problem. In an aspect, a STA receives, from an AP and via a PCH, a first trigger frame indicating a first RA-RU. The STAdecrements a first OBO counter for the PCH. The STA determines that a PPDU being received via the PCH comprises an inter- BSS PPDU. Based on the determining, the STA switches from the PCH to an NPCA PCH. The STA initializes a second OBO counter for the NPCA PCH In response to a second trigger frame, indicating a second RA-RU and received via the NPCA PCH, a value of the first OBO counter is maintained and the second OBO counter is decremented.

[0156] FIG. 16 illustrates a further example 1600 operation according to an embodiment. As shown in FIG.16, example 1600 includes an AP 1601 and a STA 1602 associated with AP 1601 . AP 1601 and STA 1602 may both support NPCA operation and may operate over a plurality of channels, including a PCH, an NPCA PCH, a first secondary channel (SCH1), and a second secondary channel (SCH2).

[0157] Example 1600 may begin with AP 1601 and STA 1602 operating on the PCH. In an embodiment AP 1601 and STA 1602 operate using UORA for transmission on the PCH, as discussed above in relation to FIGS. 7-9. AP 1601 transmits a frame 1603 to STA 1602. In an embodiment, frame 1603 is a trigger frame. For example, like trigger frame 720 illustrated in FIG. 7, frame 1603 may indicate RA-RUs and scheduled RUs for STAs associated with AP 1601. Frame 1603 may identify a number R of RA-RUs for use by the STAs associated with AP 1601 , including STA 1602. For example, frame 1603 may identify five RA-RUs.

[0158] In an embodiment, STA 1602 has previously initialized a first OBO counter (OBO_1) (e.g., to 15). Upon receiving frame 1603, STA 1602 may decrement the first OBO counter OBO_1 by the number of eligible RA-RUs indicated in frame 1603 (e.g., five RA-RUs). Once the first OBO counter OBO_1 of STA 1602 decrements to 0 (negative OBO are clipped to 0), STA 1602 may transmit any pending frames (not pictured) on a selected RU (e.g., a randomly selected RU from an eligible set of RA-RUs, or a dedicated RU), depending on the RU allocation by AP 1601 in frame 1603

[0159] While AP 1601 and STA 1602 operate on the PCH, transmission of a frame 1604 from an OBSS may begin on the PCH. AP 1601 and STA 1602 may detect frame 1604 on the PCH. In an implementation, AP 1601 and STA 1602 may be configured to set a NAV associated with the PCH based on receiving frame 1604 on the PCH. Frame 1604 may indicate a transmission (of one or more frames including frame 1604) on the PCH. A duration of the transmission on the PCH may be provided by a duration field of frame 1604, a TXOP duration field of an OBSS PPDU comprising frame 1604, or a length field of the OBSS PPDU. AP 1601 and STA 1602 may set their NAVs for the PCH based on the OBSS NAV duration or OBSS TXOP duration.

[0160] In accordance with NPCA operation, on receiving an OBSS PPDU and obtaining the OBSS NAV duration, AP 1601 and STA 1602 may be configured to switch to the NPCA PCH for the OBSS NAV duration. AP 1601 and STA 1602 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.

[0161] In an example, AP 1601 and STA 1602 may use trigger based NPCA operation, in which AP 1601 initiates a transmission opportunity in the NPCA PCH for STA 1602. For example, AP 1601 may transmit aframe 1606 via the NPCA PCH to STA 1602. Frame 1606 may be an initial control frame (IGF), which may be used in a variety of operations (e.g., dynamic power saving, dynamic subband operation and device coexistence features). Alternatively, frame 1606 may be a BSRP frame used to poll stations of their uplink transmit buffer.

[0162] Further, in an embodiment, frame 1606 may comprise a trigger frame. For example, like frame 1603, frame 1606 may indicate RA-RUs and scheduled RUs for STAs associated with AP 1601. Frame 1606 may be transmitted on the NPCA PCH and may identify a number R of RA-RUs for use by the STAs associated with AP 1601, including STA 1602, during transmission on the NPCA PCH. For example, frame 1606 may identify five RA-RUs.

[0163] In an embodiment, STA 1602 may use a second OBO counter (OBO_2) for UORA transmission on the NPCA PCH. As illustrated, STA 1602 may initialize the second OBO counter OBO_2 for use in the NPCA PCH. That is, instead of using a same OBO counter OBO_1 for both the PCH and NPCA PCH, STA 1602 may initialize the second OBO counter OBO_2 for use in the NPCA PCH. For example, STA 1602 may initialize the second OBO counter OBO_2 to four (e.g., based on an OCW, as discussed below) for use in the NPCA PCH, as illustrated in example 1600. STA 1602 may maintain the first OBO counter OBO_1 for the PCH, and the second OBO counter OBO_2 for the NPCA PCH.

[0164] In other words, as discussed above, a STA (e.g., STA 1602) that supports UORA may store the current values of its OBO and OCW each time the STA switches to the NPCA primary channel. If a STA receives a trigger frame indicating an RA-RU, the STA may set its OCW to OCWmin and may initialize its OBO in the range of 0 to OCW. The STA may use the same UORA parameter set values for operation on the NPCA primary channel as it uses on the BSS primary channel.

[0165] In an embodiment, AP 1601 indicates in frame 1606 whether STA 1602 is to initialize the second OBO counter OBO_2. Alternatively, or in addition, STA 1602 may receive an indication to initialize the second OBO counter OBO_2 in another suitable frame, or STA 1602 may be pre-configured to initialize the second OBO counter OBO_2 (e.g., without receiving an indication to initialize the second OBO counter).

[0166] Further, the OCW for the second OBO counter OBO_2 may be indicated by AP 1601 in frame 1606. As discussed above in relation to FIGS. 7-9, the OCW may indicate the range of an OFDMA contention window for STAs to initiate random access. As illustrated in example 1600, frame 1606 indicates an OCW of eight to STA 1602. Alternatively, or in addition, the OCW for the second OBO counter OBO_2 may be indicated in any other suitable frame(s), or may be a predetermined value. For example, the OCW for the second OBO counter OBO_2 may be set to an OCWmin value used for UORA transmission on the PCH (e.g., provided by a UORA parameter set element to STA 1602 for the PCH). In an embodiment, STA 1602 uses this OCW to initiate random access. For example, as discussed above in relation to FIGS. 7-8, STA 1602 may initialize the second OBO counter OBO_2 to an integer value randomly selected from a uniform distribution in the range 0 to OCW (e.g., four, as illustrated). The OCW may then double each time a collisionoccurs (as described in example 1400 above). In an embodiment, the updated OCW for the second OBO counter OBO_2 remains in the range OCWmin to OCWmax. The OCWmin and OCWmax values used for the first OBO counter OBO_1 , for the PCH, may also be used for the second OBO counter OBO_2. Alternatively, or in addition, the OCWmin and OCWmax values may be provided to STA 1602 by AP 1601 (e.g., as discussed below in relation to FIG. 17), may be pre-determined, or may be determined using any other suitable technique.

[0167] As in examples 1400 and 1500 discussed above, after receiving frame 1606 identifying a number R of RA-RUs, STA 1602 may decrement its second OBO counter OBO_2 for the NPCA PCH by R, and once the second OBO counter OBO_2 eventually reaches 0, STA 1602 may transmit a frame 1608 (e.g., an ICR or BSR) to AP 1601 using the NPCA PCH. In an embodiment, STA 1602 maintains the value of the first OBO counter OBO_1 for the PCH and does not decrement the first OBO counter OBO_1 for the PCH upon receiving frame 1606 via the NPCA PCH.

[0168] AP 1601 may then transmit a frame 1610 to STA 1602 using the NPCA PCH. STA 1602 may respond to frame 1610 with a BA frame 1612. Alternatively, or in addition, AP 1601 may share the TXOP to STA 1602 so that STA 1602 may transmit an UL frame (not pictured) to AP 1601 using the NPCA PCH. In an embodiment, initializing a second OBO counter for NPCA PCH transmission may improve the efficiency of NPCA PCH transmission (e.g., trigger based NPCA PCH transmission).

[0169] FIG. 17 illustrates another example operation 1700 according to an embodiment. As shown in FIG.17, example 1700 includes an AP 1701 and a STA 1702 associated with AP 1701 . AP 1701 and STA 1702 may both support NPCA operation and may operate over a plurality of channels, including a PCH, an NPCA PCH, a first secondary channel (SCH1), and a second secondary channel (SCH2). In an embodiment AP 1701 and STA 1702 operate using UORA, as discussed above in relation to FIGS. 7-9, for transmission on the PCH and NPCA PCH.

[0170] Example 1700 may begin with AP 1701 transmitting a frame 1714 to STA 1702 using SCH2. In an embodiment, frame 1714 may indicate an OCWmin and OCWmax for UORA on the NPCA PCH. For example, the OCWmin and OCWmax for the NPCA PCH may be signaled in a UORA parameter set element similar to the OCWmin and OCWmax for the PCH (e.g., as discussed above in relation to UORA Parameter Set element 800 illustrated in FIG. 8). As discussed further below, STA 1702 may use the OCWmin and OCWmax indicated in frame 1714 to set a second OBO counter (OBO_2) for use when STA 1702 contends for an RA-RU in the NPCA PCH.

[0171] In an embodiment, after AP 1701 transmits frame 1714, AP 1701 transmits a frame 1703 to STA 1702 using the PCH. In an embodiment, frame 1703 is a trigger frame for transmission on the PCH. For example, like trigger frame 720 illustrated in FIG. 7, frame 1703 may indicate RA-RUs and scheduled RUs for STAs associated with AP 1701 . Frame 1703 may identify a number R of RA-RUs for use by the STAs associated with AP 1701 , including STA 1702. For example, frame 1703 may identify five RA-RUs.

[0172] In an embodiment, STA 1702 has previously initialized a first OBO counter (OBO_1) (e.g., to 15) for transmission on the PCH. Upon receiving frame 1703, STA 1702 may decrement the first OBO counter OBO_1 by the number of eligible RA-RUs indicated in frame 1703 (e.g., five RA-RUs). Once the first OBO counter OBO_1 of STA 1702 decrements to 0 (negative OBO are clipped to 0), STA 1702 may transmit any pending frames (not pictured) on a selected RU using the PCH (e.g., a randomly selected RU from an eligible set of RA-RUs, or a dedicated RU), depending on the RU allocation by AP 1701 in frame 1703.

[0173] While AP 1701 and STA 1702 operate on the PCH, transmission of a frame 1704 from an OBSS may begin on the PCH. AP 1701 and STA 1702 may detect frame 1704 on the PCH. In an implementation, AP 1701 and STA 1702 may be configured to set a NAV associated with the PCH based on receiving frame 1704 on the PCH. Frame 1704 may indicate a transmission (of one or more frames including frame 1704) on the PCH. A duration of the transmission on the PCH may be provided by a duration field of frame 1704, a TXOP duration field of an OBSS PPDU comprising frame 1704, or a length field of the OBSS PPDU. AP 1701 and STA 1702 may set their NAVs for the PCH based on the OBSS NAV duration or OBSS TXOP duration.

[0174] In accordance with NPCA operation, on receiving an OBSS PPDU and obtaining the OBSS NAV duration, AP 1701 and STA 1702 may be configured to switch to the NPCA PCH for the OBSS NAV duration. AP 1701 and STA 1702 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.

[0175] In an example, AP 1701 and STA 1702 may use trigger based NPCA operation, in which AP 1701 initiates a transmission opportunity in the NPCA PCH for STA 1702. For example, AP 1701 may transmit a frame 1706 via the NPCA PCH to STA 1702. Frame 1706 may be an initial control frame (ICF), which may be used in a variety of operations (e.g., dynamic power saving, dynamic subband operation and device coexistence features). Alternatively, frame 1706 may be a BSRP frame used to poll stations of their uplink transmit buffer.

[0176] Further, in an embodiment, frame 1706 may comprise a trigger frame. For example, like frame 1703, frame 1706 may indicate RA-RUs and scheduled RUs for STAs associated with AP 1701. Frame 1706 may be transmitted on the NPCA PCH and may identify a number R of RA-RUs for use by the STAs associated with AP 1701, including STA 1702, during transmission on the NPCA PCH. For example, frame 1706 may identify five RA-RUs.

[0177] In an embodiment, STA 1702 may use the second OBO counter OBO_2 for UORA transmission on the NPCA PCH. As illustrated, like example 1600 illustrated in FIG. 16, STA 1702 may initialize the second OBO counter OBO_2 for use in the NPCA PCH. That is, instead of using the same OBO counter OBO_1 for both the PCH and NPCA PCH, STA 1702 may initialize the second OBO counter OBO_2 for use in the NPCA PCH. STA 1702 may maintain the first OBO counter OBO_1 for the PCH, and the second OBO counter OBO_2 for the NPCA PCH.

[0178] In other words, as discussed above, a STA (e.g., STA 1702) that supports UORA may store the current values of its OBO and OCW each time the STA switches to the NPCA primary channel. If a STA receives a trigger frame indicating an RA-RU, the STA may set its OCW to OCWmin and may initialize its OBO in the range of 0 to OCW. The STA may use the same UORA parameter set values for operation on the NPCA primary channel as it uses on the BSS primary channel.

[0179] In an embodiment, AP 1701 indicates in frame 1706 whether STA 1702 is to initialize the second OBO counter OBO_2. Alternatively, or in addition, STA 1702 may receive an indication to initialize the second OBO counter OBO_2 in any other suitable frame, or may be pre-configured to initialize the second OBO counter OBO_2 (e.g., without receiving an indication to initialize the second OBO counter).

[0180] In an embodiment, STA 1702 uses the OCWmin and OCWmax indicated in frame 1714 to set the second OBO counter OBO_2. For example, STA 1702 may initialize an OCW to OCWmin (e.g., eight, as illustrated in example 1700) As discussed above in relation to FIGS. 7-8, STA 1702 may initialize the second OBO counter OBO_2 to a value in the range of 0 to OCW (e.g., to an integer value randomly selected from a uniform distribution in the range 0 to OCW): four, as illustrated in example 1700. The OCW may then double each time a collision occurs, as long as the updated OCW is less than the value of OCWmax (e.g., 64 as illustrated). STA 1702 may then randomly select its second OBO counter OBO_2 in the range of 0 and the updated OCW. Once the OCW reaches OCWmax for successive retransmission attempts, the OCW may remain at the value of OCWmax. STA 1702 may update its OCW value under the condition that the updated OCW remains in the range OCWmin to OCWmax.

[0181] As in examples 1400 and 1500 discussed above, after receiving frame 1706 identifying a number R of RA-RUs, STA 1702 may decrement its second OBO counter OBO_2 for the NPCA PCH by R, and once the second OBO counter OBO_2 eventually reaches 0, STA 1702 may transmit a frame 1708 to AP 1701 using the NPCA PCH (e.g., an ICR or BSR). In an embodiment, STA 1702 maintains the value of the first OBO counter OBO_1 for the PCH and does not decrement the first OBO counter OBO_1 for the PCH upon receiving frame 1706 via the NPCA PCH.

[0182] AP 1701 may then transmit a frame 1710 to STA 1702 using the NPCA PCH. STA 1702 may respond to frame 1710 with a BA frame 1712. Alternatively, or in addition, AP 1701 may share the TXOP to STA 1702 so that STA 1702 may transmit an UL frame (not pictured) to AP 1701 using the NPCA PCH. In an embodiment, initializing a second OBO counter for NPCA PCH transmission (e.g., using OCWmin and OCWmax values provided by AP 1701) may improve the efficiency of NPCA PCH transmission (e.g., trigger based NPCA PCH transmission).

[0183] FIG. 18 illustrates an additional example operation 1800 according to an embodiment. As shown in FIG. 18, example 1800 includes an AP 1801 and a STA 1802 associated with AP 1801. AP 1801 and STA 1802 may both support NPCA operation and may operate over a plurality of channels, including a PCH, an NPCA PCH, a first secondary channel (SCH1), and a second secondary channel (SCH2).

[0184] Example 1800 may begin with AP 1801 and STA 1802 operating on the PCH. In an embodiment AP 1801 and STA 1802 operate using UORA for transmission on the PCH, as discussed above in relation to FIGS. 7-9. AP 1801 transmits a frame 1803 to STA 1802. In an embodiment, frame 1803 is a trigger frame. For example, like trigger frame 720 illustrated in FIG. 7, frame 1803 may indicate RA-RUs and scheduled RUs for STAs associated with AP 1801. Frame 1803 may identify a number R of RA-RUs for use by the STAs associated with AP 1801 , including STA 1802. For example, frame 1803 may identify five RA-RUs.

[0185] In an embodiment, STA 1802 has previously initialized an OBO counter (e.g., to 15). Upon receiving frame 1803, STA 1802 may decrement the OBO counter by the number of eligible RA-RUs indicated in frame 1803 (e.g., five RA-RUs). Once the OBO counter of STA 1802 decrements to 0 (negative OBO are clipped to 0), STA 1802 may transmit any pending frames (not pictured) on a selected RU (e.g., a randomly selected RU from an eligible set of RA-RUs, or a dedicated RU), depending on the RU allocation by AP 1801 in frame 1803.

[0186] While AP 1801 and STA 1802 operate on the PCH, transmission of a frame 1804 from an OBSS may begin on the PCH. AP 1801 and STA 1802 may detect frame 1804 on the PCH. In an implementation, AP 1801 and STA 1802 may be configured to set a NAV associated with the PCH based on receiving frame 1804 on the PCH. Frame 1804 may indicate a transmission (of one or more frames including frame 1804) on the PCH. A duration of the transmission on the PCH may be provided by a duration field of frame 1804, a TXOP duration field of an OBSS PPDU comprising frame 1804, or a length field of the OBSS PPDU. AP 1801 and STA 1802 may set their NAVs for the PCH based on the OBSS NAV duration or OBSS TXOP duration.

[0187] In accordance with NPCA operation, on receiving an OBSS PPDU and obtaining the OBSS NAV duration, AP 1801 and STA 1802 may be configured to switch to the NPCA PCH for the OBSS NAV duration. AP 1801 and STA 1802 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.

[0188] In an example, AP 1801 and STA 1802 may use trigger based NPCA operation, in which AP 1801 initiates a transmission opportunity in the NPCA PCH for STA 1802. For example, AP 1801 may transmit a frame 1806 via the NPCA PCH to STA 1802. Frame 1806 may be an initial control frame (IGF), which may be used in a variety of operations (e.g., dynamic power saving, dynamic subband operation and device coexistence features). Alternatively, frame 1806 may be a BSRP frame used to poll stations of their uplink transmit buffer

[0189] Further, in an embodiment, frame 1806 may comprise a trigger frame. For example, like frame 1803, frame 1806 may indicate RA-RUs and scheduled RUs for STAs associated with AP 1801. Frame 1806 may be transmitted on the NPCA PCH and may identify a number R of RA-RUs for use by the STAs associated with AP 1801 , including STA 1802 during transmission on the NPCA PCH. For example, frame 1806 may identify five RA-RUs.

[0190] In an embodiment, STA 1802 may use an OBO counter for UORA transmission on the NPCA PCH. For example, in one embodiment STA 1802 may use an existing OBO counter, used for UORA transmission on the PCH (e g., in response to frame 1803), for UORA transmission on the NPCA PCH (e.g., in response to frame 1806). This is discussed further, above, in relation to example 1400 illustrated in FIG. 14. In an embodiment, however, STA 1802 may decrement the OBO counter differently for transmission on the NPCA PCH compared with transmission on the PCH.

[0191] For example, in example 1400 a STA 1402 may decrement an OBO counter by the number R of RA-RUs provided in a frame 1406. In an embodiment, STA 1802 may decrement an OBO counter by a multiple, N, of the number of RA-RUs provided in frame 1806. For example, AP 1801 may indicate a value of N in frame 1806 (e.g., three as illustrated). STA 1802 may decrement the OBO counter by N x R (e.g., 3 x 5 = 15), rather than by R.

[0192] In an embodiment, a value for N may be provided to STA 1802 by AP 1801 in frame 1806. This is merely an example, and N can be provided to STA 1802 in any suitable transmission, or may be predetermined (e.g., without requiring any transmission). In an embodiment, AP 1801 may set a value for N based on the number of STAs associated with AP 1801 that support NPCA PCH operation. For example, if one third of STAs associated with AP 1801 support NPCA PCH operation, AP 1801 could set N to three.

[0193] As illustrated, STA 1802 decrements its OB counter by 15 (e.g., by Nx R). Once the OBO counter eventually reaches 0, STA 1802 may transmit a frame 1808 (e.g., an ICR or BSR) to AP 1801 using the NPCA PCH. AP 1801 may then transmit a frame 1810 to STA 1802 using the NPCA PCH. STA 1802 may respond to frame 1810 with a BA frame 1812. Alternatively, or in addition, AP 1801 may share the TXOP to STA 1802 so that STA 1802 may transmit an UL frame (not pictured) to AP 1801 using the NPCA PCH In an embodiment, speeding up the decrementing of an OBO counter for NPCA PCH transmission, as compared to PCH transmission, may improve the efficiency of NPCA PCH transmission (e.g., in case the OBO counter used for PCH operation has a high value and / or a fraction of STAs associated with an AP support NPCA PCH operation).

[0194] As would be understood by a person of skill in the art based on the teachings herein, the embodiments as described by the above examples may be readily extended to implementations including more than one STA.

[0195] As would be understood by a person of skill in the art based on the teachings herein, the embodiments as described by the above examples may be readily extended to implementations including more than one AP.

[0196] As would be understood by a person of skill in the art based on the teachings herein, the embodiments as described by the above examples may be readily extended to scenarios in which any of the APs or any of the STAs may comprise a MLD, comprising at least one affiliated AP or affiliated STA.

[0197] FIG. 19 illustrates an example process 1900 according to an embodiment. Example process 1900 may be performed by a suitable STA, such as STA 1402 illustrated in FIG. 14, STA 1602 illustrated in FIG.16, STA 1702 illustrated in FIG 17, or STA 1802 illustrated in FIG. 18, for example. As shown in FIG. 19, process 1900 may include step 1902.

[0198] Step 1902 includes switching, by a station (STA), from a first channel to a second channel. In an embodiment the STA includes any suitable STA, including STA 1402 illustrated in FIG. 14, STA 1602 illustrated in FIG. 16, STA 1702 illustrated in FIG. 17, or STA 1802 illustrated in FIG. 18, for example.

[0199] Step 1904 includes initializing a second orthogonal frequency division multiple access (OFDMA) backoff (OBO) counter for the second channel.

[0200] Step 1906 includes receiving, by the STA from an access point (AP) and via the second channel, a first trigger frame (TF) indicating a first random access resource unit (RA-RU). In an embodiment, the AP includes any suitable AP, including AP 1401 illustrated in FIG. 14, AP 1601 illustrated in FIG. 16, AP 1701 illustrated in FIG. 17, or AP 1801 illustrated in FIG. 18, for example.

[0201] Step 1908 includes maintaining a value of a first OBO counter for the first channel.

[0202] In an embodiment, initializing the second OBO counter comprises setting the value of the second OBO counter in a range from 0 to an OFDMA contention window (OCW).

[0203] In an embodiment, the OCW is at least one of: a predetermined value, or indicated in the first TF.

[0204] In an embodiment, the process 1900 further includes receiving, by the STA from the AP, a first frame indicating the OCW.

[0205] In an embodiment, the OCW is an integer ranging from a minimum value (OCWmin) to a maximum value (OCWmax).

[0206] In an embodiment, the process 1900 further includes receiving, by the STA from the AP, a second frame indicating at least one of the OCWmin and the OCWmax .

[0207] In an embodiment, the at least one of the OCWmin and the OCWmax is provided in an uplink OFDMA-based random access (UORA) parameter set element of the second frame

[0208] In an embodiment, the UORA parameter set element is for the second channel

[0209] In an embodiment, the OCW is equal to a minimum value (OCWmin) of an uplink OFDMA-based random access (UORA) parameter set element of the first channel.

[0210] In an embodiment, initializing the second OBO counter comprises setting a value of the second OBO counter based on the value of the first OBO counter.

[0211] In an embodiment, the initializing the second OBO counter comprises setting the value of the second OBO counter equal to the value of the first OBO counter.

[0212] In an embodiment, the process 1900 further includes transmitting a physical protocol data unit (PPDU) via the second channel in response to the first TF.

[0213] In an embodiment, the PPDU comprises an ultra high reliability (UHR) PPDU.

[0214] In an embodiment, the transmitting of the PPDU is based on the second OBO counter decrementing to 0 based on a total number / count of RA-RUs in the first TF.

[0215] In an embodiment, transmitting the PPDU is based on the second OBO counter being less than the total number / count of RA-RUs multiplied by a factor N.

[0216] In an embodiment, the factor N is at least one of: a value indicated in the first TF, a predetermined value, or one.

[0217] In an embodiment, maintaining the value of the first OBO counter comprises not decrementing the first OBO counter in response to the first TF.

[0218] In an embodiment, initializing the second OBO counter comprises initializing the second OBO counter after switching, by the STA, from the first channel to the second channel.

[0219] In an embodiment, the process 1900 further includes decrementing, by the STA, the second OBO counter in response to the first TF

[0220] In an embodiment, the process 1900 further includes receiving, by the STA from the AP and via the first channel, a second TF indicating a second RA-RU, and decrementing, by the STA, the first OBO counter in response to the second TF.

[0221] In an embodiment, the process 1900 further includes receiving, by the STA from the AP, a third frame indicating that the AP transmits a trigger frame in the second channel that includes at least one RA-RU.

[0222] In an embodiment, the first channel comprises a primary channel (PCH).

[0223] In an embodiment, the second channel is a non-primary channel access (NPCA) PCH.

[0224] FIG. 20 illustrates an example process 2000 according to an embodiment. Example process 2000 may be performed by a suitable AP, such as AP 1401 illustrated in FIG. 14, AP 1601 illustrated in FIG. 16, AP 1701 illustrated in FIG. 17, or AP 1801 illustrated in FIG. 18, for example. As shown in FIG. 20, process 2000 may include step 2002.

[0225] Step 2002 includes switching, by an access point (AP), from a first channel to a second channel. In an embodiment, the AP includes any suitable AP, including AP 1401 illustrated in FIG. 14, AP 1601 illustrated in FIG. 16, AP 1701 illustrated in FIG. 17, or AP 1801 illustrated in FIG. 18, for example.

[0226] Step 2004 includes transmitting, by the AP to a station (STA) and via the second channel, a first trigger frame (TF). In an embodiment the STA includes any suitable STA, including STA 1402 illustrated in FIG. 14, STA 1602 illustrated in FIG. 16, STA 1702 illustrated in FIG. 17, or STA 1802 illustrated in FIG. 18, for example.

[0227] In an embodiment the TF indicates a first random access resource unit (RA-RU).

[0228] In an embodiment the TF further indicates a parameter for a first orthogonal frequency division multiple access (OFDMA) backoff (OBO) counter for the second channel.

[0229] In an embodiment, the parameter for the first OBO counter comprises an indication of an OFDMA contention window (OCW).

[0230] In an embodiment, the parameter for the first OBO counter comprises the 0CW.

[0231] In an embodiment, the OCW is an integer ranging from a minimum value (OCWmin) to a maximum value (OCWmax).

[0232] In an embodiment, the parameter for the first OBO counter indicates at least one of the OCWmin and the OCWmax.

[0233] In an embodiment, the at least one of the OCWmin and the OCWmax is provided in an uplink OFDMA-based random access (UORA) parameter set element of the first TF.

[0234] In an embodiment, the UORA parameter set element is for the second channel.

[0235] In an embodiment, the OCW is equal to a minimum value (OCWmin) of an uplink OFDMA-based random access (UORA) parameter set element of the first channel.

[0236] In an embodiment, the parameter for the first OBO counter indicates setting the value of the first OBO counter based on a value of a second OBO counter for the first channel.

[0237] In an embodiment, the parameter for the first OBO counter for the second channel indicates setting the value of the first OBO counter equal to the value of the second OBO counter.

[0238] In an embodiment, the process 2000 further includes receiving a physical protocol data unit (PPDU) via the second channel in response to the first TF.

[0239] In an embodiment, the PPDU comprises an ultra high reliability (UHR) PPDU.

[0240] In an embodiment, wherein the parameter for the first OBO counter relates to decrementing the first OBO counter based on a total number / count of RA-RUs in the first TF.

[0241] In an embodiment, the parameter for the first OBO counter comprises a factor N for decrementing the first OBO counter based on the total number / count of RA-RUs in the first TF multiplied by a factor N.

[0242] In an embodiment, the factor N is at least one of: determined by the AP, a predetermined value, or one.

[0243] In an embodiment, the factor N is determined by the AP based on a number of STAs associated with the AP supporting operation via the second channel.

[0244] In an embodiment, the process 2000 further includes transmitting, by the AP to the STA, a third frame indicating that the AP transmits a trigger frame in the second channel that includes at least one RA-RU.

[0245] In an embodiment, the first channel comprises a primary channel (PCH).

[0246] In an embodiment, the second channel comprises a non-primary channel access (NPCA) PCH.

[0247] In an embodiment, a STA / AP described in any of the embodiments above may further perform one or more of the NPCA operations described herein below. As would be understood by a person of skill in the art based on the teachings, any of the NPCA operations described below may be combined with the procedures / operations described above.

[0248] Hereinafter, a STA that supports NPCA operation is called an NPCA STA. An AP that supports NPCA operation is called an NPCA AP. A non-AP NPCA STA may set an NPCA Supported field of a UHR MACCapabilities Information field of a UHR Capabilities element to 1. In an implementation, a non-AP NPCA STA does not enable the NPCA mode unless the non-AP NPCA STA is associated with an NPCA AP that has enabled NPCA operation.

[0249] In an implementation, an NPCA AP that has an operating bandwidth less than 80 MHz does not enable NPCA operation. In an implementation, an AP of a multiple BSSID set that enables NPCA operation may indicate the same NPCA primary channel, same NPCA minimum duration, same NPCA switching delay, and same NPCA switch back delay as all of the other APs of the same multiple BSSID set that have enabled NPCA operation. In an implementation, an AP of a co-hosted BSS that enables NPCA operation may indicate the same NPCA primary channel, same NPCA minimum duration, same NPCA switching delay, and same NPCA switch back delay as all of the other APs of the same co-hosted BSSs that have enabled NPCA operation.

[0250] In an implementation, an NPCA AP that has enabled NPCA operation may set to 1 the NPCA Enabled field in the UHR Operation element of the (Re)Association Response, UHR Link Reconfiguration Notify, Beacon and Probe Response frames that it transmits.

[0251] In an implementation, an NPCA AP with a value (e.g., dotHHEPSROption Implemented) set to true may set the TXVECTOR parameter SPATIAL_REUSE to PSR_DISALLOW for PPDUs that it transmits, and may set the PSR Disallowed subfield in the SR Control field of the Spatial Reuse Parameter Set element to 1 in Management frames it transmits before enabling NPCA operation in its BSS and while NPCA operation remains enabled.

[0252] In an implementation, an AP may enable a PHY Header-based (PHYLEN) NPCA operation by setting a MAC Header-based (MOPLEN) NPCA field to 0 and may enable both PHYLEN NPCA and MOPLEN NPCA operation by setting the MOPLEN NPCA field to 1.

[0253] In an implementation, an NPCA AP may advertise an NPCA Disabled Subchannel Bitmap field in the NPCA Operation Parameters field. The NPCA Disabled Subchannel Bitmap field may indicate the subchannels that are punctured when an NPCA STA operates on the NPCA primary channel:If an NPCA Disabled Subchannel Bitmap field is present, then the NPCA Disabled Subchannel Bitmap Field Present bit may be set to 1 , otherwise the NPCA Disabled Subchannel Bitmap Field Present field may be set to 0.The NPCA Disabled Subchannel Bitmap field value may satisfy the following requirements:• The puncturing pattern indicated by the value of the NPCA Disabled Subchannel Bitmap field is a valid non-OFDMA puncturing pattern.• A 20 MHz subchannel indicated as punctured in the Disabled Subchannel Bitmap field of an EHT Operation element (if any) is also indicated as punctured in the NPCA Disabled Subchannel Bitmap field.An NPCA AP may indicate one or more 20 MHz subchannels as punctured in the NPCA Disabled Subchannel Bitmap field of the EHT Operation Element for the purpose of maximizing the BW of the NPCA operating channel.An NPCA AP may indicate one or more 20 MHz subchannels as punctured in the NPCA Disabled Subchannel Bitmap field of the EHT Operation Element for the purpose of creating a gap between the PPDU that initiated the NPCA switch and the NPCA operating channel.If no NPCA Disabled Subchannel Bitmap field is present in the NPCA Operation Parameters field transmitted by the AP that the STA is associated with, then the subchannels may be punctured during NPCA operation.

[0254] In an implementation, an NPCA AP may indicate a value in the NPCA Primary Channel field, of transmitted NPCA Operation Parameters fields, that corresponds to a channel that is located within the secondary 40 MHz of the BSS operating channel if the BSS is an 80 MHz BSS, thatcorresponds to a channel that is located within the secondary 80 MHz of the BSS operating channel if the BSS is a 160 MHz BSS, and that corresponds to a channel that is located within the secondary 160 MHz of the BSS operating channel if the BSS is a 320 MHz BSS.

[0255] In an implementation, a non-AP NPCA STA may indicate an NPCA switching delay and an NPCA switch back delay, respectively, in the NPCA Switching Delay field and NPCA Switch Back Delay fields of the OMP Request frames.

[0256] In an implementation, when a non-AP STA that supports NPCA mode (re)associates with an AP, the NPCA mode may be disabled by default for the non-AP STA. In the UHR OMP request sent to enable or update the parameters of NPCA mode for the non-AP STA, a non-AP STA may include the following in the Mode Parameters field of the Mode Tuple field:NPCA switching delay,NPCA switch back delay.

[0257] In an implementation, for a non-AP STA to enable NPCA mode, the associated AP must support NPCA and must have NPCA enabled for the BSS.

[0258] In an implementation, if an NPCA AP that has enabled NPCA operation advertises MU EDCA parameters in the Beacon frames that it transmits, a MU EDCA protocol may apply jointly on both BSS primary channel and NPCA primary channel for a non-AP NPCA STA. In an implementation, an NPCA STA may maintain a single MU EDCA timer that is shared across the BSS primary channel and the NPCA primary channel, transition from using EDCA parameters to using MU EDCA parameters (and vice-versa) at the same time on both the BSS primary channel and the NPCA primary channel based on certain conditions that occur on either the BSS primary channel or the NPCA primary channel, and when the STA is operating on the NPCA primary channel, use the same MU EDCA parameters as are used on the BSS primary channel exceptthat AIFSN[AC] may be set to 0 for all ACs. When the STA switches back to the BSS primary channel, it may revert to using the AIFSN[AC] values from the dot11 MUEDCATable.

[0259] In an implementation, an NPCA STA does not switch to the NPCA primary channel for NPCA operation if NPCA mode has not been enabled by its associated AP.

[0260] In an implementation, an NPCA STA may switch to the NPCA primary channel for NPCA operation if the NPCA mode has been enabled for the BSS of which it is a member and either condition 1 ) or 2) is met: 1) the STA received a PPDU and / or received a PHY-RXSTART. indication primitive for an HE / EHT / UHR PPDU on the BSS primary channel and all of the following conditions are true:a) Condition 2) is not true.b) The PPDU is classified by the STA as in inter-BSS PPDU.c) At least one of the following conditions is true:1) The value of the MAC variable NPCA_PPDU_REM_DUR derived from the received PPDU is greater than the value indicated in the most recently received or transmitted NPCA Minimum Duration Threshold field corresponding to the BSS of which the STA is a member.ii) If the NPCA AP corresponding to the BSS of which the STA is a member has enabled MOPLEN NPCA in addition to PHYLEN NPCA and the value of the MAC variable NPCA_PHY_TXOP_REM_DUR derived from the received PPDU is greater than the value indicated in the most recently received or transmitted NPCA Minimum Duration Threshold field corresponding to the BSS of which the STA is a member.d) The bandwidth of the PPDU is determined by the STA to be 20, 40, 80 or 160 MHz, based on the Bandwidth field in the PHY preamble of the PPDU and the channel occupied by the PPDU does not overlap with the NPCA primary channel.e) If the STA maintains an intra-BSS NAV, it is zero.2) All of the following conditions are true:a) A sequence of three PPDUs, separated by aSIFSTime, is identified on the BSS primary channel, comprising an initial Control frame, an initial response frame, and a third PPDU following the initial response frame.b) The STA received at least the first PPDU containing the initial Control frame and the PHY-RXSTART. indication and / or the PHY-RXEARLYSIG. indication of the third PPDU.c) An indication that a valid TXOP was obtained on the BSS primary channel, as verified by the receipt of a PHY-RXEARLYSIG. indication or PHYRXSTART. indication primitive corresponding to the third PPDU that occurs during a time window that:i) begins at aSIFSTime + ICR_Timeout after the MAC receives a PHY-RXEND. indication primitive corresponding to the first PPDU, where ICR_Timeout is equal to:(1) The length (in usee) of the expected CTS if the initial Control frame is an RTS or an MU-RTS Trigger frame,(2) the value of RXTIME calculated using Equation (27-147) with the value of LENGTH replaced by the value from the UL Length field of the Common Info field, if the initial Control frame is a BSRP Trigger frame or a BSRP NTB Trigger frame.ii) has a duration that is equal to NPCA_START_TIMEOUT which is aSIFSTime + (2 x aSlotTime) + aRxPHYStartDelay.d) At least one of the three PPDUs in the sequence of PPDUs is classified by the STA as an inter-BSS PPDU.e) At least one of the following conditions is true:i) The NPCA AP corresponding to the BSS of which the STA is a member has enabled PHYLEN NPCA only and the value of the MAC variable NPCA_PPDU_REM_DUR derived from the received third PPDU of the sequence of PPDUs is greater than the value indicated in the most recently received or transmitted NPCA Minimum Duration Threshold field corresponding to its BSS.ii) If the NPCA AP corresponding to the BSS of which the STA is a member has enabled MOPLEN NPCA in addition to PHYLEN NPCA and the value of the MAC variable NPCA_CFRAME_TXOP_REM_DUR derived from the received first PPDU (containing the initial Control frame of the control frame exchange) of the sequence of PPDUs is greater than the value indicated in the most recently received or transmitted NPCA Minimum Duration Threshold field corresponding to its associated BSS.f) The bandwidth of the third PPDU is determined by the STA to be 20, 40, 80, 160 or 320 MHz based on the Bandwidth field in the PHY preamble of the PPDU not overlap with the NPCA primary channel and the channel occupied by the PPDU does not overlap with the NPCA primary channel.g) If the STA maintains an intra-BSS NAV, it is zero at the time of the receipt of the PHYRXSTART.indication and / or the PHY-RXEARLYSIG.indication of the first PPDU.

[0261] In an implementation, when a PHY-CCA.indication(BUSY) primitive corresponding to the start of the reception of a PPDU is indicated at an NPCA STA while operating on the BSS primary channel, the values of the MAC variables NPCA_PPDU_REM_DUR, NPCA_PHY_TXOP_REM_DUR and NPCA_TIMER are all set to 0. When a PHY-CCA.indication(BUSY) corresponding to the start of the reception of a PPDU containing an initial Control frame is indicated at an NPCA STA while operating on the BSS primary channel, the MAC variable NPCA_CFRAME_TXOP_REM_DUR is set to 0.

[0262] In an implementation, the MAC variable NPCA_PPDU_REM_DUR derived from a received PPDU is equal to the value in usee, of the remaining duration of the received PPDU, determined by the MAC at the time of the receipt of the PHY-RXSTART. indication primitive associated with the received PPDU, by subtracting the time elapsed between the reception of the PHY-CCA.indication(BUSY) and PHY-RXSTART. indication primitives associated with the received PPDU from the value of RXTIME of the received PPDU.

[0263] In an implementation, the MAC variable NPCA_PHY_TXOP_REM_DUR derived from a received PPDU is:Set to 0, if the RXVECTOR parameter TXOP_DURATION is UNSPECIFIED, or if the NPCA AP corresponding to the BSS of which the STA is a member has not enabled MOPLEN NPCA.Otherwise, it is equal to the value in usee, of the remaining duration of the PPDU, determined by the MAC at the time of the receipt of the PHY-RXSTART. indication primitive associated with the received PPDU, by subtracting the time elapsed between the reception of the PHY-CCA.indication(BUSY) and PHY-RXSTART. indication primitives associated with the received PPDU from the value of RXTIME corresponding to the received PPDU, plus the value of the TXOP_DURATION parameter of the RXVECTOR of the PPDU.

[0264] In an implementation, the MAC variable NPCA_CFRAME_TXOP_REM_DUR derived from a received PPDU is:Set to 0, if the NPCA AP corresponding to the BSS of which the STA is a member has not enabled MOPLEN NPCA.Otherwise, it is set to the value in the Duration / ID field of the initial Control frame in the received PPDU at the receipt of the PHY-RXEND. indication primitive of the PPDU that contained the frame. The value of NPCA_CFRAME_TXOP_REM_DUR is reduced by the amount of time elapsed between the PHY-RXEND.indication primitive of the initial Control frame from which the value of NPCA_CFRAME_TXOP_REM_DUR was determined and the PHY-RXSTART. indication primitive of the third PPDU of the frame exchange sequence identified in condition 2) above at the time of the receipt of the PHY-RXSTART. indication primitive of the third PPDU.

[0265] In an implementation, when an NPCA STA switches to the NPCA primary channel for NPCA operation, then the following rules apply:1 ) If the STA switches from the BSS primary channel to the NPCA primary channel based on meeting condition 1) described above, the STA initiates the switch at the NPCA HE switch time and shall be ready to transmit and receive frames (subject to its capabilities and operating mode) on the NPCA primary channel no later than the value of its most recently indicated NPCA switching delay after the NPCA HE switch time. The NPCA HE switch time is the point in time immediately after the reception of the HE-SIG-A / U-SIG field of the received PPDU from condition 1) above.2) If the STA switches from the BSS primary channel to the NPCA primary channel based on meeting condition 2) described above, the STA initiates the switch at the NPCA NHT switch time and shall be ready to transmit and receive frames addressed to it (subject to its capabilities and operating mode) on the NPCA primary channel no later than the value of its most recently indicated NPCA switching delay after the NPCANHT switch time. The NPCA NHT switch time is equal to the point in time that is 3 x TSYM after the reception of the L-SIG field of the third PPDU of the received sequence of PPDUs from condition 2) above.3) The STA uses the same EDCA parameter set and EPCS EDCA parameter set values for operation on the NPCA primary channel as it uses on the BSS primary channel.4) At each NPCA HE switch time or NPCA NHT switch time, as appropriate, if the STA is an AP or if the STA is a non-AP STA and transmission of frames that are not a response to a Trigger frame is not disabled by the MU EDCA protocol, the STA may initiate a TXOP on the NPCA primary channel with the following exceptions:a) Each time that the STA switches to the NPCA primary channel, the STA does:I) If condition 1) is met, set NPCA_CFRAME_TXOP_REM_DUR to O, set NPCA_TIMER to the largest non-zero value of the variables NPCA_PPDU_REM_DUR, NPCA_PHY_TXOP_REM_DUR and NPCA_CFRAME_TXOP_REM_DUR, minus the switch back delay that the STA indicated in the most recently transmitted NPCA Operation Parameters field.II) Store the existing values of the variables QSRC[AC], CW[AC] and the backoff counter for each EDCAF.iii) Set QSRC[AC] for each AC to the value of the Initial NPCA QSRC field of the NPCA Operation Parameters received from its associated NPCA AP.iv) initialize variables CW[AC] to 2lnit-QSRc_NPCAx(CWmin[AC] + 1) - 1.v) invoke the backoff procedure even if the medium for the NPCA primary channel is not busy. vi) initiate countdown of the MAC variable NPCA_TIMER in units of 1 usee.5) A first STA does not initiate a transmission on the NPCA primary channel to a second STA until the NPCA switching delay time of the second STA has elapsed since the NPCA HE switch time at the first STA if the first STA is switching due to condition 1) above or since the NPCA NHT switch time at the first STA if the first STA is switching due to condition 2) above.6) The STA begins all frame exchanges on the NPCA primary channel with an initial control frame (ICF) using non-HT PPDU or non-HT duplicate PPDU format using a rate of 6 Mb / s, 12 Mb / s, or 24 Mb / s. a) For TXOPs initiated by an AP, the ICF is a BSRP Trigger frame or an MU-RTS Trigger frame except when at least one of the target non-AP STA(s) is operating in the DUO mode, in which case, the ICF may be a BSRP Trigger frame or a BSRP NTB Trigger frame but not an MU-RTS. In addition, the ICF conforms to the rules for Dynamic Unavailability Operation (DUO) mode if at least one of the target non-AP STA(s) is operating in DUO mode, to the rules for Enhanced multi-link single-radio (EMLSR) operation if at least one of the target non-AP STA(s) is affiliated with a non-AP MLD that is operating in EMLSR mode, and to the rules for Dynamic power save (DPS) operation if at least one of the target non-AP STA(s) is operating in DPS mode.b) For TXOPs initiated by a non-AP STA, the initial control frame is a BSRP NTB Trigger frame, except that if the non-AP STA is operating in the Dynamic Unavailability Operation mode (DUO), then the IGF conforms to the DUO mode rules.7) An NPCAAP that transmits a Trigger frame on the NPCA primary channel indicates RU index values that use the NPCA primary channel as the reference primary channel.8) An NPCA STA that transmits a Trigger frame on the NPCA primary channel sets the NPCA Primary Indication field to 1 in the Special User Info field, otherwise, this field is set to 0.9) The 20 MHz channels occupied by PPDUs transmitted by the STA shall meet all of the following conditions:a) include at least the NPCA primary channel.b) all be within the BSS bandwidth.c) not include any of the channels occupied by either the PPDU mentioned in condition 1) or by the third PPDU mentioned in condition 2), whichever caused the STA to switch from the BSS primary channel to the NPCA primary channel.d) not include channels that are indicated as punctured in the Disabled Subchannel Bitmap field in the EHT Operation element or in the NPCA Disabled Subchannel Bitmap field in the UHR Operation element.10) UHR ELR PPDUs, HE ER SU PPDUs, EHT MCS14 / 15 shall not be transmitted on the NPCA primary channel.11) Dynamic Subband Operation shall not be used on the NPCA primary channel.12) If TBTT for the BSS occurs while an NPCA AP is operating on the NPCA primary channel, the scheduling of the transmission of the Beacon frame and following group addressed frames shall be deferred until immediately after the AP switches back to the BSS primary channel.

[0266] In an example, an AP and associated STAs are not required to switch back to the BSS primary channel at TBTT. The group addressed frames may be buffered and delivered immediately following the next DTIM Beacon, unless explicitly specified otherwise. Further, in an example, exponential backoff may apply on the NPCA primary channel when there are failed transmissions.

[0267] In an implementation, an NPCA STA shall switch back to the BSS primary channel when the NPCA_TIMER expires. In an implementation, when the STA switches back to the BSS primary channel, it may:1) replace the current values of the variables QSRC[AC], CW[AC] and the backoff counter for each EDCAF with the values that it stored when it switched to the NPCA primary channel.2) resume the backoff procedure.

Claims

CLAIMSWhat is claimed is:

1. A method comprising:receiving, by a station (STA) from an access point (AP) and via a primary channel (PCH), a first trigger frame indicating a first random access resource unit (RA-RU);decrementing, by the STA, a first orthogonal frequency division multiple access (OFDMA) backoff (OBO) counter for the PCH;determining, by the STA, that a physical protocol data unit (PPDU) being received via the PCH comprises an inter-basic service set (BSS) PPDU;based on the determining, switching, by the STA, from the PCH to a non-primary channel access (NPCA) PCH;initializing a second OBO counter for the NPCA PCH; andin response to a second trigger frame, indicating a second RA-RU and received via the NPCA PCH,maintaining a value of the first OBO counter; anddecrementing the second OBO counter.

2. A method comprising:switching, by a station (STA), from a first channel to a second channel;initializing a second orthogonal frequency division multiple access (OFDMA) backoff (OBO) counter for the second channel;receiving, by the STA from an access point (AP) and via the second channel, a first trigger frame (TF) indicating a first random access resource unit (RA-RU); andmaintaining a value of a first OBO counter for the first channel.

3. The method of claim 2, wherein initializing the second OBO counter comprises setting the value of the second OBO counter in a range from 0 to an OFDMA contention window (OCW).

4. The method of claim 3, wherein the OCW is at least one of:a predetermined value; orindicated in the first TF.

5. The method of any of claims 3-4, further comprising receiving, by the STA from the AP, a first frame indicating the OCW.

6. The method of any of claims 3-5, wherein the OCW is an integer ranging from a minimum value (OCWmin) to a maximum value (OCWmax)7. The method of claim 6, further comprising receiving, by the STA from the AP, a second frame indicating at least one of the OCWmin and the OCWmax.

8. The method of claim 7, wherein the at least one of the OCWmin and the OCWmax is provided in an uplink OFDMA-based random access (UORA) parameter set element of the second frame.

9. The method of claim 8, wherein the UORA parameter set element is for the second channel.

10. The method of claim 3, wherein the OCW is equal to a minimum value (OCWmin) of an uplink OFDMA-based random access (UORA) parameter set element of the first channel.

11. The method of claim 2, wherein initializing the second OBO counter comprises setting a value of the second OBO counter based on the value of the first OBO counter.

12. The method of claim 11, wherein initializing the second OBO counter comprises setting the value of the second OBO counter equal to the value of the first OBO counter.

13. The method of any of claims 2-12, further comprising transmitting a physical protocol data unit (PPDU) via the second channel in response to the first TF.

14. The method of claim 13, wherein the PPDU comprises an ultra high reliability (UHR) PPDU.

15. The method of any of claims 13-14, wherein the transmitting of the PPDU is based on the second OBO counter decrementing to 0 based on a total number / count of RA-RUs in the first TF.

16. The method of claim 15, wherein transmitting the PPDU is based on the second OBO counter being less than the total number / count of RA-RUs multiplied by a factor N.

17. The method of claim 16, wherein the factor N is at least one of:a value indicated in the first TF;a predetermined value; orone.

18. The method of any of claims 2-17, wherein maintaining the value of the first OBO counter comprises not decrementing the first OBO counter in response to the first TF.

19. The method of any of claims 2-18, wherein initializing the second OBO counter comprises initializing the second OBO counter after switching, by the STA, from the first channel to the second channel.

20. The method of any of claims 2-19, further comprising decrementing, by the STA, the second OBO counter in response to the first TF.

21. The method of any of claims 2-20, further comprising:receiving, by the STA from the AP and via the first channel, a second TF indicating a second RA-RU; anddecrementing, by the STA, the first OBO counter in response to the second TF.

22. The method of any of claims 2-21, further comprising receiving, by the STA from the AP, a third frame indicating that the AP transmits a trigger frame in the second channel that includes at least one RA- RU.

23. The method of any of claims 2-22, wherein the first channel comprises a primary channel (PCH).

24. The method of any of claims 2-22, wherein the second channel comprises a non-primary channel access (NPCA) PCH.

25. A method comprising:transmitting, by an access point (AP) and via a primary channel (PCH), a first trigger frame indicating a first random access resource unit (RA-RU);receiving, by the AP from a station (STA), a first physical layer protocol data unit (PPDU) in response to the first trigger frame;determining, by the AP, that a second PPDU being received via the PCH comprises an inter- basic service set (BSS) PPDU;based on the determining, switching, by the AP, from the PCH to a non-primary channel access (NPCA) PCH; andtransmitting, by the AP and via NPCA PCH, a second TF indicating:a second RA-RU; anda parameter for initializing, by the STA, a first orthogonal frequency division multiple access (OFDMA) backoff (OBO) counter for the NPCA PCH.

26. A method comprising:switching, by an access point (AP), from a first channel to a second channel; and transmitting, by the AP to a station (STA) and via the second channel, a first trigger frame (TF) indicating:a first random access resource unit (RA-RU); anda parameter for a first orthogonal frequency division multiple access (OFDMA) backoff (OBO) counter for the second channel.

27. The method of claim 26, wherein the parameter for the first OBO counter comprises an indication of an OFDMA contention window (OCW).

28. The method of claim 27, wherein the parameter for the first OBO counter comprises the OCW.

29. The method of any of claims 27-28, wherein the OCW is an integer ranging from a minimum value (OCWmin) to a maximum value (OCWmax).

30. The method of claim 29, wherein the parameter for the first OBO counter indicates at least one of the OCWmin and the OCWmax31. The method of claim 30, wherein the at least one of the OCWmin and the OCWmax is provided in an uplink OFDMA-based random access (UORA) parameter set element of the first TF.

32. The method of claim 31 , wherein the UORA parameter set element is for the second channel.

33. The method of claim 27, wherein the OCW is equal to a minimum value (OCWmin) of an uplink OFDMA-based random access (UORA) parameter set element of the first channel.

34. The method of claim 26, wherein the parameter for the first OBO counter indicates setting a value of the first OBO counter based on a value of a second OBO counter for the first channel.

35. The method of claim 34, wherein the parameter for the first OBO counter for the second channel indicates setting the value of the first OBO counter equal to the value of the second OBO counter.

36. The method of any of claims 26-35, further comprising receiving a physical protocol data unit (PPDU) via the second channel in response to the first TP.

37. The method of claim 36, wherein the PPDU comprises an ultra high reliability (UHR) PPDU.

38. The method of any of claims 26-37, wherein the parameter for the first OBO counter relates to decrementing the first OBO counter based on a total number / count of RA-RUs in the first TF.

39. The method of claim 38, wherein the parameter for the first OBO counter comprises a factor N for decrementing the first OBO counter based on the total number / count of RA-RUs in the first TF multiplied by a factor N.

40. The method of claim 39, wherein the factor N is at least one of:determined by the AP;a predetermined value; orone.

41. The method of claim 40, wherein the factor N is determined by the AP based on a number of STAs associated with the AP supporting operation via the second channel.

42. The method of any of claims 26-41 , further comprising transmitting, by the AP to the STA, a third frame indicating that the AP transmits a trigger frame in the second channel that includes at least one RA-RU43. The method of any of claims 26-42, wherein the first channel comprises a primary channel (PCH).

44. The method of any of claims 26-43, wherein the second channel comprises a non-primary channel access (NPCA) PCH.

45. A device comprising:one or more processors; andmemory storing instructions that, when executed by the one or more processors, cause the device to perform a method according to any of claims 1-44.

46. A non-transitory computer-readable medium comprising instructions that, when executed by one or more processors, cause the one or more processors to perform a method according to any of claims 1- 44.

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