Transmission opportunity initiation

Abstract

A first station (STA) receives, from a second STA, a block acknowledgement request (BAR) frame: soliciting a block acknowledgement (BA) frame from the first STA, initiating a transmit opportunity (TXOP), and indicating whether the first STA is required to perform a carrier sense (CS) operation during a short inter frame space (SIFS) duration after receiving the BAR frame. Based on the BAR frame indicating that the first STA is required to perform the CS operation, the first STA performs the CS operation during the SIFS duration after receiving the BAR frame. Based on a result of the CS operation indicating idle, the first STA transmits, to the second STA and in response to the BAR frame, the BA frame.

Description

TITLETransmission Opportunity InitiationCROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims the benefit of U.S. Provisional Application No. 63 / 658,572, filed June 11 , 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 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 protocol data unit (PPDU).

[0008] FIG. 6 illustrates example block acknowledgment request (BAR) frames.

[0009] FIG. 7 illustrates an example of an operation that initiates a transmission opportunity (TXOP).

[0010] FIG. 8 illustrates an example of a power save (PS) mode.

[0011] FIG. 9 illustrates an example of an AP implementation of the PS mode illustrated in FIG. 8.

[0012] FIG. 10 illustrates example formats of a trigger frame, a BAR frame, and a block acknowledgment (BA) frame.

[0013] FIG. 11 illustrates an example that highlights a problem that may arise in association with an operation that initiates a TXOP.

[0014] FIG. 12 illustrates an example of an operation that initiates a TXOP according to an embodiment.

[0015] FIG. 13 illustrates an example of an operation that initiates a TXOP according to an embodiment.

[0016] FIG. 14 illustrates an example of an operation that initiates a TXOP according to an embodiment.

[0017] FIG. 15 illustrates an example process according to an embodiment of the present disclosure.

[0018] FIG. 16 illustrates another example process according to an embodiment of the present disclosure.DETAILED DESCRIPTION

[0019] 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 that shown. For example, the actions listed in any flowchart may be re-ordered or only optionally used in some embodiments.

[0020] 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.

[0021] 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.

[0022] 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”) isindicative 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.

[0023] 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.

[0024] In this disclosure, parameters (or equally called, fields, or Information elements: lEs) 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.

[0025] 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.

[0026] 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 combinationthereof, 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.

[0027] FIG. 1 illustrates example wireless communication networks 100 in which embodiments of the present disclosure may be implemented.

[0028] As shown in FIG. 1 , the example wireless communication networks 100 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) 1 10 and 120 and a distribution system (DS) 130.

[0029] BSS 110-1 and 110-2 each includes a set of an access point (AP or AP STA) and at least one station (STA or non-AP STA). For example, BSS 110-1 includes an AP 104-1 and a STA 106-1 , and BSS 1 10-2 includes an AP 104-2 and STAs 106-2 and 106-3. The AP and the at least one STA in a BSS perform an association procedure to communicate with each other.

[0030] 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).

[0031] 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.

[0032] The example wireless communication networks illustrated in FIG. 1 may further include one or more ad-hoc networks or independent BSSs (IBSSs). An ad-hoc network or IBSS is a network that includes a plurality of STAs that are within communication range of each other. The plurality of STAs are configured so that they may communicate with each other using direct peer-to-peer communication (i.e., not via an AP).

[0033] 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 doesnot 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.

[0034] 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.

[0035] 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 PLOP service data unit (PSDU). For example, the PSDU may include a PHY Convergence Protocol (PLCP) 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 802.1 1 protocol to be used to transmit the payload.

[0036] A frequency band may include one or more sub-bands or frequency channels. For example, PPDUs conforming to the IEEE 802.11 n, 802.11ac, 802.11 ax and / or 802.11 be standard amendments may be transmitted over the 2.4 GHz, 5 GHz, and / or 6 GHz bands, each of which may be divided into multiple 20 MHz channels. The PPDUs may be transmitted over a physical channel having a minimum bandwidth of 20 MHz. Larger channels may be formed through channel bonding. For example, PPDUs may be transmitted over physical channels having bandwidths of 40 MHz, 80 MHz, 160 MHz, or 520 MHz by bonding together multiple 20 MHz channels.

[0037] FIG. 2 is a block diagram illustrating example 200 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.

[0038] 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 morecontrollers 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.

[0039] 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.

[0040] 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.

[0041] FIG. 3 illustrates an example format of a MAC frame 300. 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.

[0042] As shown in FIG. 3, MAC frame 300 includes a MAC header, a variable length frame body, and a frame check sequence (FCS).

[0043] The MAC header includes a frame control field, an optional duration / ID field (not in PS-Poll frames), address fields, an optional sequence control field, an optional QoS control field (only in QoS Data frames), and an optional high throughput (HT) control field (only in +HTC frames).

[0044] 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 high throughput control (+HTC).

[0045] 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.

[0046] 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 framecontrol field, is defined as the QoS subfield. When the QoS subfield is set to 1 , it indicates a QoS subtype 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 contains no frame body field.

[0047] The To DS subfield indicates whether a data frame is destined to the DS. The From DS subfield indicates whether a data frame originates from the DS.

[0048] The more fragments subfield is set to 1 in all data or management frames that have another fragment to follow of the MAC service data unit (MSDU) or MAC management protocol data unit (MMPDU) carried by the MAC frame. It is set to 0 in all other frames in which the more fragments subfield is present.

[0049] 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.

[0050] The power management subfield is used to indicate the power management mode of a STA.

[0051] 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.

[0052] The protected frame subfield is set to 1 if the frame body field contains information that has been processed by a cryptographic encapsulation algorithm.

[0053] The +HTC subfield indicates that MAC frame 300 contains an HT control field A frame that contains the HT Control field is referred to as a +HTC frame. A Control Wrapper frame is a +HTC frame.

[0054] The duration / ID field of the MAC header indicates various contents depending on frame type and subtype and the QoS capabilities of the sending STA. For example, in control frames of the power save poll (PS-Poll) subtype, the duration / ID field carries an association identifier (AID) of the STA that transmitted the frame in the 14 least significant bits (LSB), and the 2 most significant bits (MSB) are both set to 1 . In other frames sent by STAs, the duration / 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 it must defer from accessing the shared medium.

[0055] There can be up to four address fields in the format of MAC frame 300. These fields are used to indicate the basic service set identifier (BSSID), source address (SA), destination address (DA), transmitter address (TA), and receiver address (RA). Certain frames might not contain some of the address fields. Certain address field usage may be specified by the relative position of the address field (1-4) within the MAC header, independent of the type of address present in that field. Specifically, the address 1 field alwaysidentifies the intended receiver(s) of the frame, and the address 2 field, where present, always identifies the transmitter of the frame.

[0056] The sequence control field includes two subfields, a sequence number subfield and a fragment number subfield. The sequence number subfield in data frames indicates the sequence number of the MSDU (if not in an Aggregated MSDU (A-MSDU)) or A-MSDU. The sequence number subfield in management frames indicates the sequence number of the frame. The fragment number subfield indicates the number of each fragment of an MSDU or MMPDU. The fragment number is set to 0 in the first or only fragment of an MSDU or MMPDU and is incremented by one for each successive fragment of that MSDU or MMPDU. The fragment number is set to 0 in an 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.

[0057] The QoS control field identifies the traffic category (TC) or traffic stream (TS) to which MAC frame 300 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.

[0058] 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. The control frame subtype for which HT control field is present is the control wrapper frame. A control frame that is described as +HTC (e.g., a request to send (RTS)+HTC, clear to send (CTS)+HTC, block acknowledgment (BlockAck or BA)+HTC or block acknowledgment request (BlockAckReq or BAR)+HTC frame) implies the use of the control wrapper frame to carry that control frame.

[0059] The frame body field is a variable length field that contains information specific to individual frame types and subtypes. It may include one or more MSDUs or MMPDUs. The minimum length of the frame body is 0 octets.

[0060] 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.

[0061] FIG. 4 illustrates an example 400 of a 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.

[0062] 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).

[0063] 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 onthe 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).

[0064] 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.)

[0065] 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.

[0066] In a frame sent by or to a non-High Efficiency (non-HE) STA, the following rules may apply to the queue size value:

[0067] 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.

[0068] 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.

[0069] A queue size value of 254 is used for all sizes greater than 64 768 octets.

[0070] 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:

[0075] QS =16 x(JV, if SF is equal to 0;1024 + 256 x UV, if SF is equal to 1 ;17 408 + 2048 x UV, if SF is equal to 2;148 480 + 32 768 x UV, if SF is equal to 3 and UV is less than 62;> 2 147 328, 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.

[0076] Unspecified or Unknown, if SF is equal to 3 and UV is equal to 63.

[0077] 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.

[0078] The HT control field may include a BSR control subfield which may contain buffer status information used for UL multi-user (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.

[0079] The ACI bitmap subfield indicates the access categories for which buffer status is reported (e.g., B0: best effort (AC_BE), B1 : background (AC_BK), B2: video (AC_VI), B3: voice (AC_VO), 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.

[0080] 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.

[0081] 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 ACJ3E, ACI value 1 mapping to AC_BK, ACI value 2 mapping to AC_VI, and ACI value 3 mapping to AC_VO.

[0082] The scaling factor subfield indicates the unit SF, in octets, of the queue size high and queue size all subfields.

[0083] 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.

[0084] 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.

[0085] 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) in deliveryqueues used for MSDUs and A-MSDUs associated with AC(s) that are specified in the ACI high and ACI bitmap subfields, respectively.

[0086] 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 "Vo 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.

[0087] 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.

[0088] FIG. 5 illustrates an example format of a PPDU. As shown, the PPDU may include a PHY preamble, a PHY header, a PSDU, and tail and padding bits.

[0089] 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.

[0090] 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.

[0091] 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.

[0092] 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 an UP parameter. An aggregated MPDU (A-MPDU) may include MPDUs with different TID values.

[0093] 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)

[0094] 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.

[0095] 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

[0096] 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.

[0097] 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.

[0098] 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 for that AC.

[0099] 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.

[0100] FIG. 6 illustrates example block acknowledgment request (BlockAckReq or BAR) frames 602 and 604. Example BAR frame 602 may be a compressed BAR frame variant, and example BAR frame 604 may be a multi-TID BAR frame variant. As shown in FIG. 6, example BAR frame variants 602 and 604 may each comprise a frame control field, a duration field, a receiver address (RA) field, a transmitter address (TA) field, a BAR control field, a BAR information field, and / or frame check sequence (FCS) field.

[0101] The Frame Control field may include the following subfields (not shown): protocol version, type, subtype, To DS, From DS, more fragments, retry, power management, more data, protected frame, and +HTC.

[0102] The Duration / ID field is set to the estimated time required to transmit one Ack frame or BlockAck (BA) frame, as applicable, plus one SIFS.

[0103] The RA field indicates the address of a recipient STA of BAR frame variant 602 or 604.

[0104] The TA field indicates the address of a STA transmitting BAR frame variant 602 or 604 or a bandwidth signaling TA.

[0105] The BAR control field includes a first reserved subfield, a BAR type subfield, a second reserved subfield, and a TID_INFO subfield.

[0106] The BAR type subfield of the BAR control field indicates the frame variant of the BAR frame. For example, the BAR type subfield set to 1 indicates an extended compressed BAR frame variant. The BAR type subfield set to 2 indicates a compressed BAR frame variant such as BAR frame 602. The BAR type subfield set to 3 indicates a multi-TID BAR frame variant such as BAR frame 604. The BAR type subfield set to 6 indicates a groupcast with retries (GCR) BAR frame variant. The BAR type subfield set to 10 indicates ageneral link groupcast with retries (GLK-GCR) BAR frame variant. The values 0, 4-5, 7-9, and 11 -15 are currently reserved.

[0107] The meaning of the TID_INFO subfield of the BAR Control field depends on the BAR frame variant type indicated by the BAR type subfield. For example, for a compressed BAR frame variant such as BAR frame 602, the TID_I NFO subfield of the BAR Control field contains the TID for which a BA frame is requested.

[0108] The meaning of the BAR Information field of the BAR frame depends on the BAR frame variant type. For example, for a compressed BAR frame variant such as BAR frame 602, the BAR Information field contains a Block Ack Starting Sequence Control subfield. The Block Ack Starting Sequence Control subfield may include a Fragment Number subfield and a Starting Sequence Number subfield. For a multi-TID BAR frame variant such as BAR frame 604, the BAR Information field includes, for each TID, a Per TID Info subfield and a Block Ack Starting Sequence Control subfield. The Per TID Info subfield include a reserved subfield and a TID value subfield that indicates the TID.

[0109] The FCS field may be used by a STA to validate a received frame and to interpret certain fields from the MAC headers of a frame.

[0110] FIG. 7 illustrates an example 700 of an operation that initiates a TXOP. As shown in FIG. 7, example 700 may include an AP 702 and a STA 704. STA 704 may be associated with AP 702.

[0111] As shown in FIG. 7, the operation of example 700 may begin with AP 702 transmitting a BAR frame 710 to STA 704. The transmission of BAR frame 710 initiates a TXOP 750A owned by AP 702. BAR frame 710 may indicate a duration of TXOP 750A. As shown in FIG. 7, in an example, a duration of TXOP 750A may be configured to be at least equal to the estimated transmission time of a BA frame 720A from STA 704 to AP 702, a data frame 760 from AP 702 to STA 704, a BA frame 720B from STA 704 to AP 702, and 766A- C durations (SIFS 766A between BAR frame 710 and BA frame 720A, SIFS 766B between BA frame 720A and data frame 760, and SIFS 7660 between data frame 760 and BA frame 720B).

[0112] After receiving BAR frame 710 (SIFS 766A after receiving BAR frame 710), STA 704 transmits BA frame 720A to AP 702. BAR frame 710 may request acknowledgments for one or more frames (not shown in FIG. 7) previously transmitted by AP 702 to STA 704. As such, BA frame 720A may include the acknowledgments requested by BAR frame 710. BA frame 720A may indicate a remaining duration 750B of TXOP 750A.

[0113] Continuing example 700, after receiving BA frame 720A (SIFS 766B after receiving BA frame 720A), AP 702 transmits data frame 760 to STA 704 After receiving data frame 760 (SIFS 766C after receiving data frame 760), STA 704 transmits BA frame 720B to AP 702.

[0114] FIG. 8 illustrates an example 800 of a power save (PS) mode. As shown in FIG. 8, example 800 includes STAs 802 and 804. STAs 802 and 804 may each be an AP STA or a non-AP STA. It is assumed that STA 804 implements the PS mode illustrated in FIG. 8, which may be denoted as a dynamic PS mode or a low power listening (LPL) mode.

[0115] In an implementation, a STA (AP STA or non-AP STA) implementing the PS mode illustrated in FIG. 8 may be in a first power state of the PS mode or in a second power state of the PS mode. The first power state may be referred to as a lower power receive state or a listen / listening state. The second power state may be referred to as a high power receive state or an awake state. While in the first power state, the STA is capable of receiving PPDUs of a first category. While in the second power state, the STA is capable of receiving PPDUs of the first category and PPDUs of a second category. In an implementation, the STA is not capable of receiving PPDUs of the second category during the first power state. In an implementation, the STA is capable of receiving PPDUs of only the first category during the first power state.

[0116] In an implementation, the first category may include PPDUs having a non-HT PPDU format. In another implementation, the first category may include, additionally or alternatively, PPDUs having a data rate that is less than or equal to 24 Mbps, a bandwidth of 20 MHz, and / or a single spatial stream. The second category may include PPDUs having a format other than the non-HT PPDU format. For example, the second category may include PPDUs having a high throughput (HT) format, such as a HT Mixed Mode PPDU, a VHT format such as VHT PPDU, an HE PPDU such as HE SU PPDU, HE MU PPDU, or HE ER SU PPDU, an EHT PPDU such as EHT MU PPDU, an ultra-high reliability (UHR) PPDU, or a physical layer version identifier field. Additionally, or alternatively, the second category may include PPDUs having a data rate that is greater than 24 Mbps, a bandwidth greater than 20 MHz, and / or a plurality of spatial streams.

[0117] The STA may transition between the first power state and the second power state of the PS. In an implementation, to reduce the power consumption of the STA, the first power state may correspond to a default state of the PS mode. As such, the STA may operate in the first power state and may transition to the second power state as needed.

[0118] In an implementation, as illustrated in example 800, the STA may transition from the first power state to the second power state in response to being solicited by another STA. For example, as shown in FIG. 8, STA 804, which implements the PS mode, may operate in the first power state and may transition to the second power state in response to a solicitation from STA 802. Specifically, STA 802 may transmit an initial control frame (ICF) 806 to STA 804 requesting that STA 804 transition from the first power state to the second power state of the PS mode. STA 802 may request that STA 804 transition from the first power state to the second power state in order to transmit to STA 804 a PPDU 810 of the second category that STA 804 is not capable of receiving during the first power state (e.g., an EHT PPDU, a PPDU having a bandwidth greater than 20 MHz, and / or a PPDU having multiple spatial streams). In an implementation, ICF 806 may be a request to send (RTS) frame, a multi-user RTS (MU-RTS) frame or a BAR frame. ICF 806 may be carried in a PPDU of the first category. In an implementation, ICF 806 may be carried in a PPDU using a non-HT duplicate format with a bandwidth of 40 MHz, 80 MHz, 160 MHz or 320 MHz. In an implementation, ICF 806 may include signaling indicating the PPDU bandwidth.

[0119] On receiving ICF 806, STA 804 initiates a transition from the first power state to the second power state. For example, on receiving ICF 806, STA 804 may enable / power on receiver capabilities needed to receive the PPDU of the second category that STA 802 wishes to transmit to STA 804 The transition from the first power state to the second power state may be associated with a state transition duration. The state transition duration may depend on the processing capabilities of STA 804. In an implementation, STA 802 may include padding in ICF 806 to allow STA 804 to transition from the first power state to the second power state in a timely manner. Hence, as shown in FIG. 8, STA 804 may start the state transition before the reception of ICF 806 is completed (i.e. without decoding the padding information).

[0120] In an implementation, STA 804 responds to ICF 806 by transmitting an initial control response (ICR) 808 to STA 802. ICR 808 informs STA 802 that STA 804 is transitioning from the first power state to the second power state. In an implementation, as shown in FIG. 8, STA 804 may transmit ICR 808 while transitioning from the first power state to the second power state. In an implementation, STA 804 may transmit ICR 808 after completing the transition from the first power state to the second power state. Completing the transition before transmitting ICR 808 may enable STA 804 to perform clear channel assessment over a bandwidth that is higher than 20 MHz. This may enable STA 804 to transmit ICR 808 on idle channels with bandwidths higher than 20 MHz, which improves hidden node protection due to the transmission of ICR 808. In another implementation, STA 804 may transmit ICR 808 before completing the transition to the second power state. In such an implementation, STA 804 may only be able to transmit ICR 808 using a bandwidth of 20 MHz. ICR 808 may be carried in a PPDU of the first category or the second category. In an implementation, STA 804 transmits ICR 808 a short interframe space (SIFS) after receiving ICF 806.

[0121] On receiving ICR 808, STA 802 initiates transmission of PPDU 810. In an implementation, STA 802 transmits PPDU 810 a SIFS after receiving ICR 808. In an implementation, STA 802 may begin transmitting PPDU 810 while STA 804 is still transitioning from the first power state to the second power state. PPDU 810 may thus include a first PPDU part 814 of the first category and a second PPDU part 816 of the second category. In another implementation, STA 802 may begin transmitting PPDU 810 after STA 804 has transitioned to the second power state. PPDU 810 may thus be entirely of the second category.

[0122] After receiving PPDU 810, STA 804 may transmit a BA frame 812 to STA 802. In an implementation, STA 804 may return to the first power state after receiving PPDU 810. STA 804 may transmit BA frame 812 while in the second power state or after returning to the first power state.

[0123] FIG. 9 illustrates an example 900 of an AP implementation of the PS mode illustrated in FIG. 8. As shown in FIG. 9, example 900 includes an AP 902 and a STA 904. STA 904 may be associated with AP 902. It is assumed that AP 902 implements the PS mode illustrated in FIG. 8. Specifically, as described above, while in the first power state of the PS mode, AP 902 is capable of receiving PPDUs of a first category; and while in the second power state of the PS mode, AP 902 is capable of receiving PPDUs of the first categoryand PPDUs of a second category. The first category and the second category may be as described above with reference to FIG. 8.

[0124] In an implementation, while in the first power state, AP 902 is capable of receiving data frames carried by PPDUs of the first category. In another implementation, AP 902 is capable of receiving PPDUs of the first category while in the first power state, AP 902 is not capable of receiving the data frames carried by PPDUs of the first category while in the first power state. In an implementation, while in the second power state, AP 902 is capable of receiving data frames carried by PPDUs of the first category or the second category.

[0125] Additionally, AP 902 may support another mode of operation. The other mode may correspond to an active mode or to a power saving mode different than the PS mode illustrated in FIG. 8. The other mode may have one or more power states. AP 902 may be capable of receiving PPDUs of the first category and / or of the second category in any power state.

[0126] In an implementation, AP 902 may be configured to announce a time period during which AP 902 will operate in the PS mode. For example, as shown in FIG. 9, during a first time period, AP 902 may transmit a frame 906 indicating or announcing a second time period during which AP 902 will operate in the PS. The second time period may or may not be adjacent to the first time period. In an implementation, AP 902 may be operating in the other mode during the first time period. In another implementation, AP 902 may be operating in the PS mode during the first time period. Frame 906 may indicate a start time T1 and an end time T2 of the second time period. Alternatively, frame 906 may indicate a start time TI and a duration of the second time period.

[0127] In an example, as shown in FIG. 9, AP 902 may be in the other mode before switching to the PS mode at the beginning of the second time period. In an implementation, AP 902 may be configured, upon switching to the PS mode from the other mode, to operate in a default state of the PS mode. In an implementation, the default state may be the first power state as described above. In another example, not shown in FIG. 9, AP 902 be in the second power state of the PS mode before the beginning of the second time period. AP 902 may switch from the second power state to the first power state of the PS mode at the beginning of the second time period.

[0128] In an implementation, as illustrated in example 900, AP 902 may transition from the first power state to the second power state in response to being solicited by a STA. For example, as shown in FIG. 9, after switching to the PS mode at the beginning of the second time period, AP 902 may operate in the first power state. Subsequently, AP 902 receives an ICF 908 requesting that AP 902 transition from the first power state to the second power state to receive from STA 904 a PPDU 912 of the second category. On receiving ICF 908 from STA 904, AP 902 may respond with an ICR 910 and may initiate a transition from the first power state to the second power state.

[0129] In an implementation, AP 902 may determine, from ICF 908, a TXOP duration, a bandwidth, and / or a modulation and coding scheme (MCS) of PPDU 912. AP 902 may turn on / enable receiver capabilities based on the bandwidth and MCS indicated in ICF 908. In an implementation, AP 902 may use the TXOP duration and the bandwidth indicated in ICF 908 to reserve a suitable channel for PPDU 912. For example, PPDU 912 may have a bandwidth of 80 MHz and AP 902 may reserve a primary 80 MHz channel for PPDU 912. In an implementation, AP 902 may perform a clear channel assessment (CCA) procedure over the channel to be used by STA 904 for the transmission of PPDU 912. After a successful CCA procedure, AP 902 may transmit an ICR 910 to STA 904. ICR 910 may be configured to reserve the channel to be used by STA 904 for the transmission of PPDU 912. In an implementation, ICR 910 may be a clear to send (CTS) frame that indicates the channel to be used by STA 904 for the transmission of PPDU 912.

[0130] On receiving ICR 910, STA 904 initiates transmission of PPDU 912. In an implementation, STA 904 transmits PPDU 912 a SIFS after receiving ICR 910. After receiving PPDU 912, AP 902 may transmit a BA frame 914 to STA 904. In an implementation, AP 902 may return to the first power state after receiving PPDU 912. AP 902 may transmit BA frame 914 while in the second power state or after returning to the first power state. After the second time period, AP 902 may transition to the other mode of operation or may remain in the first power state of the PS mode.

[0131] FIG. 10 illustrates example formats of a trigger frame 1010, a BAR frame 1020, and a BA frame 1030.

[0132] Trigger frame 1010 may be used by an AP to allocate resources for and solicit one or more TB PPDU transmissions from one or more STAs. Trigger frame 1010 may also carry other information required by a responding STA to transmit a TB PPDU to the AP. As shown in FIG. 10, trigger frame 1010 includes a Frame Control field, a Duration field, a receiver address (RA) field, a transmitter address (TA) field, a Common Info field, a User Info List field, an optional control feedback field, a Padding field, and an FCS field.

[0133] The Frame Control field may include the following subfields (not shown): protocol version, type, subtype, To DS, From DS, more fragments, retry, power management, more data, protected frame, and +HTC.

[0134] The Duration field indicates various contents depending on frame type and subtype and the QoS capabilities of the sending STA. For example, in control frames of the power save poll (PS-Poll) subtype, the Duration field carries an association identifier (AID) of the STA that transmitted the frame in the 14 least significant bits (LSB), and the 2 most significant bits (MSB) are both set to 1 . In other frames sent by STAs, the Duration field contains a duration value (in microseconds) which may be used by a recipient to update a NAV.

[0135] The RA field indicates the address of the STA that is intended to receive the incoming transmission from the transmitting station. The TA field is the address of the STA transmitting trigger frame 1010 if trigger frame 1010 is addressed to STAs that belong to a single BSS. The TA field may include the transmittedBSSID when trigger frame 1010 is addressed to STAs from at least two different BSSs of a multiple BSSID set.

[0136] The Common Info field specifies a trigger frame type of trigger frame 1010, a transmit power of trigger frame 1010 in dBm, and several key parameters of a TB PPDU that may be transmitted by a STA in response to trigger frame 1010. The trigger frame type of a trigger frame that may be used by an AP to receive QoS data using UL MU operation is referred to as a basic trigger frame. A non-AP HE STA interprets the Common Info field as HE variant. A non-AP EHT STA interprets the Common Info field as HE variant if B54 and B55 in the Common Info field are equal to 1; and interprets the Common Info field as EHT variant otherwise. The HE variant Common Info field and the EHT variant Common Info field use the same encoding method for the Trigger Type, UL Length, More TF, CS Required, LDPC Extra Symbol Segment, AP TX Power, Pre-FEC Padding Factor, PE Disambiguity, and Trigger Dependent Common Info subfields.

[0137] The User Info List field contains zero or more User Info fields. In trigger frame 1010, the variant of the User Info list field depicted includes a Special User Info field, user info field 1 , and user info field 2. The Special User Info field is a User Info field that does not carry user specific information, but rather the Special User Info field carries extended common information not provided in the Common Info field.

[0138] The optional control feedback field may indicate a link adaptation request.

[0139] The Padding field is optionally present in trigger frame 1010 to extend the frame length to give recipient STAs enough time to prepare a response for transmission one SIFS after the frame is received. The Padding field, if present, is at least two octets in length and is set to all 1s.

[0140] The FCS field may be used by a STA to validate a received frame and to interpret certain fields from the MAC headers of a frame.

[0141] As shown in FIG. 10, example BAR frame 1020 may comprise a frame control field, a duration field, a receiver address (RA) field, a transmitter address (TA) field, a BAR control field, a BAR information field, a control feedback field, a padding field, and / or a frame check sequence (FCS) field.

[0142] The Frame Control field may include the following subfields (not shown): protocol version, type, subtype, To DS, From DS, more fragments, retry, power management, more data, protected frame, and +HTC.

[0143] The Duration / ID field is set to the estimated time required to transmit one Ack or BA frame, as applicable, plus one SIFS.

[0144] The RA field indicates the address of a recipient STA of BAR frame 1020.

[0145] The TA field indicates the address of a STA transmitting BAR frame 1020 or a bandwidth signaling TA.

[0146] The BAR control field may include a first reserved subfield, a BAR type subfield, a second reserved subfield, and a TIDJNFO subfield (not shown). The BAR type subfield of the BAR control field indicates aframe variant of BAR frame 1000. For example, the BAR type subfield set to 1 indicates an extended compressed BAR frame variant. The BAR type subfield set to 2 indicates a compressed BAR frame variant. The BAR type subfield set to 3 indicates a multi-TID BAR frame variant. The BAR type subfield set to 6 indicates a groupcast with retries (GCR) BAR frame variant. The BAR type subfield set to 10 indicates a general link groupcast with retries (GLK-GCR) BAR frame variant. The values 0, 4-5, 7-9, and 11 -15 are currently reserved.

[0147] The meaning of the TID_I NFO subfield of the BAR Control field depends on the Block BAR frame variant type indicated by the BAR type subfield. For example, the TID_INFO subfield of the BAR Control field of the Compressed BAR frame contains the TID for which a BA frame is requested.

[0148] The meaning of the BAR Information field of the BAR frame depends on the BAR frame variant type. For example, the BAR Information field of the Compressed BAR frame contains a Block Ack Starting Sequence Control subfield.

[0149] The control feedback field may indicate a link adaptation request and / or a bandwidth indication.

[0150] The Padding field is optionally present in BAR frame 1020 to extend the frame length to give recipient STAs enough time to prepare a response for transmission one SIFS after the frame is received. The Padding field, if present, is at least two octets in length and is set to all 1s.

[0151] The FCS field may be used by a STA to validate a received frame and to interpret certain fields from the MAC headers of a frame.

[0152] As shown in FIG. 10, example BA frame 1030 may comprise a frame control field, a duration field, a receiver address (RA) field, a transmitter address (TA) field, a BA control field, a BA information field, a control feedback field, a padding field, and / or a frame check sequence (FCS) field.

[0153] The Frame Control field may include the following subfields (not shown): protocol version, type, subtype, To DS, From DS, more fragments, retry, power management, more data, protected frame, and +HTC.

[0154] The Duration / ID field is set to the estimated time required to transmit one Ack or BA frame, as applicable, plus one SIFS

[0155] The RA field indicates the address of a recipient STA of BA frame 1030.

[0156] The TA field indicates the address of a STA transmitting BA frame 1030 or a bandwidth signaling TA.

[0157] The BA control field may include a first reserved subfield, a BA type subfield, a second reserved subfield, and a TID_INFO subfield (not shown). The BA type subfield of the BA control field indicates a frame variant of BA frame 1030. For example, the BA type subfield set to 1 indicates an extended compressed BA frame variant. The BA type subfield set to 2 indicates a compressed BA frame variant. The BA type subfield set to 1 1 indicates a Multi-STA BA frame variant.

[0158] The meaning of the TID_INFO subfield of the BA Control field depends on the BA frame variant type indicated by the BA type subfield.

[0159] The meaning of the BA Information field of the BA frame depends on the BA frame variant type. For example, the BA Information field of the Compressed BA frame contains a Block Ack Starting Sequence Control subfield.

[0160] The control feedback field may indicate a bandwidth indication and may comprise a link adaptation response, a BSR, and / or operating mode (OM) control information.

[0161] The Padding field is optionally present in BA frame 1030 to extend the frame length to give recipient STAs enough time to prepare a response for transmission one SIFS after the frame is received. The Padding field, if present, is at least two octets in length and is set to all 1s.

[0162] The FCS field may be used by a STA to validate a received frame and to interpret certain fields from the MAC headers of a frame.

[0163] FIG. 11 illustrates an example 1100 that highlights a problem that may arise in association with an operation that initiates a TXOP. As shown in FIG. 11 , example 1100 may include a STA 1110 and a STA 1 112. STA 11 10 may comprise an AP STA. STA 1112 may comprise a non-AP STA. STA 1 112 may be associated with STA 1110. In an implementation (not shown in FIG. 1 1), STA 11 10 may comprise a non-AP STA, STA 1 112 may comprise an AP STA, and STA 1 110 may be associated with STA 1112.

[0164] As shown in FIG. 11 , the operation of example 1 100 that initiates a TXOP may begin with STA 1110 transmitting BAR frames 1120A-D to STA 1112 on respective subchannels 1 -4 of a frequency channel bandwidth to be used for communication using the TXOP. The transmission of BAR frames 1120A-B by STA 1110 initiates a TXOP with a bandwidth corresponding to the frequency channel bandwidth. In an example, STA 1110 may transmit BAR frames 1120A-D using a non-HT duplicate PPDU. The bandwidth of the non- HT duplicate PPDU may be equal to the TXOP bandwidth.

[0165] In response to BAR frames 1120A-D, STA 1 112 transmits BA frames 1125A-D on the same respective subchannels 1 -4 of the frequency channel bandwidth. In example 1100, STA 1112 is not configured to perform a carrier sense (CS) operation before transmission of BA frames 1125A-D. In an example, the CS operation is a part of the MAC protocol, specifically used by an implementation of the Carrier Sense Multiple Access with Collision Avoidance (CSMA / CA) mechanism. CS may be used to avoid collisions by determining if another device is currently transmitting on the medium.

[0166] Because the CS operation is not required, despite presence of interference 1150 at STA 1112 for subchannels 1 -2, STA 1 112 transmits BAR frames 1125A-D on subchannels 1 -4 of the frequency channel bandwidth.

[0167] Based on receiving BA frames 1 125A-D on subchannels 1 -4 of the frequency channel bandwidth, STA 1110 transmits data frame 1160 via subchannels 1-4 of the frequency channel bandwidth. However, because of interference 1150 at STA 1112 on subchannels 1-2, STA 11 12 may fail to receive and / or decodedata frame 1160, resulting in a receive error 1199 for data frame 1160. Receive error 1 199 for data frame 1160 (due to undetected interference 1150 on subchannels 1 -2) may cause an inefficient and wasteful use of network resources, including wireless channel resources required to resend data frame 1 160, processing and power resources of STA 11 10 used to process and retransmit data frame 1160, and processing and power resources of STA 1112 used to receive and process data frame 1 160 a second time.

[0168] Embodiments of the present disclosure, as further described below, address the above-described problems of existing technologies. In an aspect, a first STA may receive a first frame from a second STA, with the first frame soliciting a BA frame from the first STA, and initiating a TXOP for communication between the first STA and the second STA. The first frame may comprise an acknowledgement request frame. The acknowledgement request frame may comprise a block acknowledgement request (BAR) frame. The first frame may further comprise a field indicating that the first frame comprises the BAR frame. The first frame may comprise padding bits. The first frame may comprise a field indicating that the first frame comprises an initial control frame. The first frame may indicate whether the first STA is required to perform a CS operation during a first duration. The first frame may further comprise a field indicating that the first STA is required to perform a CS operation during the first duration. The first STA may perform the CS operation based on the first frame. Based on the CS operation, performed by the first STA during the first duration, indicating idle, the first STA may transmit the BA frame in response to the first frame. The CS operation may comprise a physical (PHY) CS and / or a virtual CS. The CS operation indicating idle may comprise both the PHY CS indicating idle and the virtual CS indicating idle. The PHY CS indicating idle may comprise at least a primary 20MHz channel indicating idle and / or zero or more secondary channels indicating idle. The PHY CS indicating busy may comprise a primary 20MHz channel indicating busy The virtual CS indicating idle may comprise a NAV indicating idle. The NAV indicating idle may comprise a NAV having a zero value. The NAV indicating busy may comprise the NAV indicating non-zero value. In another embodiment, the CS operation, performed by the first STA during the first duration, may indicate a busy condition. The CS operation indicating busy may comprise at least one of the PHY CS and the virtual CS indicating busy. Based on this busy condition, the first STA may not transmit the BA frame in response to the first frame. Because the second STA does not receive the BA frame implicated by the busy condition, the second STA may not send a data frame to the first STA based on receiving the BA frame.

[0169] FIG. 12 illustrates an example 1200 of an operation that initiates a TXOP according to an embodiment As shown in FIG. 12, example 1200 includes a STA 1210 and a STA 1212. STA 1210 may comprise an AP STA and STA 1212 may comprise a non-AP STA. STA 1212 may be associated with STA 1210. In an implementation (not shown in FIG. 12), STA 1210 may comprise a non-AP STA, STA 1212 may comprise an AP STA, and STA 1210 may be associated with STA 1212.

[0170] As shown in FIG. 12, the operation of example 1200 that initiates a TXOP may begin with STA 1210 transmitting frames 1220A-D to STA 1212 on respective subchannels 1 -4 of a frequency channel bandwidthto be used for communication using the TXOP. The transmission of frames 1220A-B by STA 1210 initiates a TXOP with a bandwidth corresponding to the frequency channel bandwidth. In an example, STA 1210 may transmit frames 1220A-D using a non-HT duplicate PPDU. The bandwidth of the non-HT duplicate PPDU may be equal to the TXOP bandwidth.

[0171] One or more of frames 1220A-D may comprise an acknowledgement request frame. In an example, the acknowledgement request frame may comprise a BAR frame, as described with FIGS. 6 and 10 above. In an implementation, the BAR frame may include a field indicating that the frame is a BAR frame. In an embodiment, frames 1220A-D may each include the acknowledgement request frame. For example, frames 1220A-D may duplicate the same acknowledgement request frame.

[0172] In an embodiment, STA 1210 may transmit frames 1220A-D on respective subchannels 1 -4 of the frequency channel bandwidth to be used for communication using the TXOP. In an implementation, the subchannels may comprise a primary channel. The primary channel may include one or more of: a 20 MHz channel, a 40 MHz channel, an 80 MHz channel, a 160 MHz channel, and a 320 MHz channel. The subchannels may further comprise one or more secondary channels. The secondary channels may include one or more of: 20MHz channels, 40MHz channels, 80MHz channels, 160MHz channels, and 320MHz channels. In an example, the bandwidth of subchannels 1-4 may be indicated in frames 1220A-D.

[0173] In an embodiment, one or more of frames 1220A-D may include a CS indication 1222. CS indication 1222 may be implemented as a CS required field of one or more of frames 1220A-D. In an embodiment, when set to a first value (e.g., 1 ) in one or more of frames 1220A-D, CS indication 1222 indicates that STA 1212 is required to perform a CS operation on subchannels 1-4 associated with the one or more of frames 1220A-D. In an implementation depicted in FIG. 12, frames 1220A-D are transmitted subchannels 1-4 with CS indication 1222 for one or more of frames 1220A-D (not shown). Based on the respective values of CS indication 1222 in the one or more of frames 1220A-D, STA 1212 may be required to perform a CS operation on any or all of subchannels 1-4 used to receive frames 1220A-D.

[0174] In an implementation, the CS operation performed on a subchannel may include a physical CS operation performed on the subchannel. The physical CS operation may include performing a clear channel assessment (CCA) on the subchannel. The physical CS operation may indicate busy for the subchannel when the CCA detects a signal on the subchannel with an energy greater than an energy detection (ED) threshold. The physical CS may indicate idle for the subchannel when the CCA does not detect a signal on the subchannel with an energy greater than the ED threshold.

[0175] Additionally, or alternatively, the CS operation performed on a subchannel may include a virtual CS operation performed for the subchannel. The virtual CS operation for the subchannel may include checking one or more network allocation vector (NAV) associated with the subchannel. The one or more NAV may include a basic (inter-BSS) NAV and / or an intra-BSS NAV associated with the subchannel. The virtual CS operation for the subchannel may indicate busy when the basic NAV and / or the intra-BSS NAV associatedwith the subchannel has a non-zero value. In an implementation, the virtual CS operation may indicate busy for the subchannel when at least one the basic NAV and the intra-BSS NAV associated with the subchannel has a non-zero value. The virtual CS operation may indicate idle for the subchannel when the basic NAV and / or the intra-BSS NAV associated with the subchannel has a zero value. In an implementation, the virtual CS operation may indicate idle for the subchannel when both the basic NAV and the intra-BSS NAV associated with the subchannel have a zero value.

[0176] In an embodiment, the CS operation performed on a subchannel may include the virtual CS operation for the subchannel based on whether the subchannel is a primary channel or a secondary channel. In an example, STA 1212 receives frame 1220A on a first subchannel (subchannel 1 ) that is a primary channel and frame 1220B on a second subchannel (subchannel 2) that is a secondary subchannel. As part of the CS operation, STA 1212 may perform the virtual CS operation for one or both of the first and second subchannels. In an embodiment, STA 1212 may perform the virtual CS operation for the first channel based on the first channel being a primary channel and may not perform the CS operation for the second channel based on the second channel being a secondary channel.

[0177] Continuing example 1200, after receiving frames 1220A-D, STA 1212 may process frames 1220A- D to determine whether STA 1212 is required to perform the CS operation on one or more subchannels used to receive frames 1220A-D. In example 1200, each of frames 1220A-D may have a CS indication 1222 set to a first value (e.g., CS = 1 ) to indicate that STA 1212 is required to perform the CS operation on the respective subchannel used to receive the frame. As such, STA 1212 may perform the CS operation for each of subchannels 1-4 used to receive frames 1220A-D. In an implementation, STA 1212 may perform the CS operation during a duration 1266 that STA 1212 waits before responding to frames 1220A-D. In different implementations, duration 1266 may correspond to a SIFS, may be longer than a SIFS, may be shorter than a PFIS, or may correspond to a PIFS.

[0178] Continuing example 1200, after performing the CS operations for subchannels 1-4 used to receive frames 1220A-D, because of interference 1250 being present on subchannels used to receive frames 1220A- B (subchannels 1 -2 in FIG. 12), the results of the CS operations may indicate that subchannels 1-2 used to receive frames 1220A-B are busy. In contrast, with no interference present on subchannels 3-4 used to receive frames 1220C-D (and, in an embodiment, the virtual CS operations for the subchannels indicating idle), the results of the CS operations may indicate that subchannels 3-4 used to receive frames 1220C-D are idle.

[0179] These CS operations required by CS indications 1222 of frames 1220A-D contrast to frames 1120A- D transmitted by STA 1 110 of example 1 100. For example, while no CS operations are performed in example 1 100 based on frames 1120A-D, STA 1212 performs CS operations on the subchannels designated by the one or more CS indications 1222.

[0180] Returning to example 1200, based on the CS operations performed based on the CS indications 1222 of frames 1220A-D, interference 1250 may be identified by STA 1212 before transmission of BA frames 1225A-D. Thus, STA 1212 may transmit BA frames 1225C-D in response to frames 1220C-D, via subchannels 3-4 used to receive frames 1220C-D, and not transmit BA frames in response to frames 1220A- B, via respective subchannels 1 -2 used to receive frames 1220A-B.

[0181] BA frames 1225C-D may be transmitted to STA 1210 using an HT PPDU or non-HT duplicate PPDU, e.g . , as described with FIG. 10 above. In an example, BA frames 1225C-D transmitted in response to frames 1220C-D are transmitted using a primary channel and a secondary channel (e.g., subchannels 3-4 respectively). The primary channel may correspond to a 20MHz channel. The secondary channel may correspond to a 20 MHz channel (e.g., first secondary 20 MHz channel). In alternative or additional implementations, the first STA may transmit BA frames 1225C-D via secondary channels.

[0182] Continuing example 1200, after receiving BA frames 1225C-D via subchannels 3-4, STA 1210 transmits data frame 1260 to STA 1212 via subchannels 3-4 used to receive BA frames 1225C-D. After STA 1212 receives data frame 1260, STA 1212 may transmit BA frames 1230C-D via subchannels 3-4 used to receive data frame 1260. In an example, data frame 1260 may be transmitted using a UHR physical layer protocol data unit (PPDU).

[0183] In example 1200, because STA 1210 did not use subchannels 1-2 subject to interference 1250 at STA 1212 to transmit data frame 1260, a receive error for data frame 1260, similar to receive error 1199 for data frame 1 160 of FIG. 11 , does not occur at STA 1212. Thus, at least based on the foregoing, embodiments depicted with FIG. 12 may avoid the problem described above with FIG. 11 .

[0184] FIG. 13 illustrates an example 1300 of an operation that initiates of a TXOP according to an embodiment. As shown in FIG. 13, example 1300 includes a STA 1310, and a STA 1312. STA 1310 may comprise an AP STA and STA 1312 may comprise a non-AP STA. STA 1312 may be associated with STA 1310. In an implementation (not shown in FIG. 13), STA 1310 may comprise a non-AP STA, STA 1312 may comprise an AP STA, and STA 1310 may be associated with STA 1312.

[0185] As shown in FIG. 13, the operation of example 1300 that initiates a TXOP may begin with STA 1310 transmitting frames 1320A-D to STA 1312. One or more of frames 1320A-D may comprise an acknowledgement request frame. In an example, the acknowledgement request frame may comprise a BAR frame, as described with FIG. 6 above.

[0186] In an embodiment, frames 1320A-D are transmitted on respective subchannels 1 -4 of a frequency channel bandwidth to be used for communication using the TXOP. In an implementation, the subchannels may comprise one primary 20MHz channel. The subchannels may comprise one or more secondary channels. The secondary channels may include one or more of: 20MHz channels, 40MHz channels, 80MHz 160MHz channels, and 320MHz channels. In an example, the bandwidth of the subchannels may be indicated in frames 1320A-D.

[0187] In an embodiment, one or more of frames 1320A-D may include ICF indications 1323. ICF indications 1323, in embodiments, may be used to indicate that STA 1312 is required to perform a CS operation on subchannels within a bandwidth indicated in the frame, e.g., subchannels 1-4 associated with the frames 1320A-D. In an implementation, frames 1320A-D may include ICF indications 1323 in a field indicating that frames 1320A-D are ICF frames. In an embodiment, when set to a first value (e.g., 1) in a frame among frames 1320A-D, ICF indications 1323 indicates that the frame is an initial control frame (ICF) such as ICF 806. The ICF may be a frame that initiates a TXOP and / or that causes another STA to transition from a first power state to a second power state of a PS mode.

[0188] In an implementation depicted in FIG. 13, frames 1320A-D are transmitted on subchannels 1-4 with ICF indications 1323 for one or more of frames 1320A-D (not shown). Based on ICF indications 1323, STA 1312 may be required to perform a CS operation on any or all of the subchannels of the bandwidth, including one or more of subchannels 1-4 used to transmit frames 1320A-D.

[0189] In an implementation, the CS operation may include at least one of a physical CS operation. The physical CS operation may include performing a clear channel assessment (CCA) on one or more of the subchannels of the bandwidth of the TXOP. The subchannels may comprise at least one of one or more 20MHz channels, one or more 40MHz channels, one or more 80MHz channels, one or more 160MHz channels, and one or more 320MHz channels.

[0190] In additional or alternative embodiments, the CS operation may include a virtual CS operation. The virtual CS operation may include MAC CS within the bandwidth of the TXOP, e.g., checking a network allocation vector (NAV) of the TXOP. In an example, frame 1320A is received on a subchannel (e.g., subchannel 1 ) that is a primary channel and frame 1320B is received on a subchannel (e g., subchannel 2) that is a secondary subchannel. The virtual CS operation may include checking the NAV of one or both of the primary and secondary subchannels. The NAVs checked by the virtual CS operation may include a basic NAV and / or an intra-BSS NAV. The NAV having non-zero value may comprise a virtual CS indicating busy. All NAVs having zero value may indicate a virtual CS indicating idle.

[0191] Continuing example 1300, after receiving one or more of frames 1320A-D via subchannels 1-4, STA 1312 initiates a TXOP for communication with STA 1310 for use of the respective subchannels 1-4 of frames 1320A-D. Frames 1320A-D may have an ICF indications 1323 that STA 1312 interprets as requiring CS operations be performed by STA 1312 on one or more subchannels of the bandwidth of the TXOP, e.g., subchannels 1-4 respectively used to transmit frames 1320A-D.

[0192] Continuing example 1300, after the TXOP is initiated, STA 1312 waits a duration 1366 before transmitting BA frames 1325C-D via subchannels 3-4. In an implementation, during this duration 1366, STA 1312 may perform the CS operations interpreted by STA 1312 as being required. In different implementations, duration 1366 may correspond to a SIFS, may be longer than a SIFS, may be less than a PIFS, or may correspond to a PIFS.

[0193] For subchannels 1-4 depicted in example 1300, interference 1350 exists for STA 1312 for subchannels 1-2 used to transmit frames 1320A-B. In example 1300, because of ICF indications 1323 associated with frames 1320A-D that are interpreted by STA 1312 as requiring CS operations, during duration 1366, STA 1312 may perform CS operations on the subchannels that include subchannels 1 -4 upon which frames 1320A-D were received. Continuing example 1300, after performing the CS operations, because of interference 1350 on subchannels 1-2, the results of the CS operations may show that subchannels 1-2 of frames 1320A-B are not idle (e.g., busy), while subchannels 3-4 of frames 1320C-D are idle.

[0194] In an implementation, the virtual CS will indicate busy when at least one of the basic NAV and the intra-BSS NAV is non-zero. Additionally or alternatively the virtual CS may indicate busy when at least one of all NAVs that the first STA considers has NAV counter that is not equal to 0. In an alternative result, the virtual CS will indicate idle when all NAVs assessed by the CS operation have NAV counters equal to 0. In example 1300, the virtual CS may indicate idle by at least all NAVs, that the first STA (STA 1312) considers, having non-zero value.

[0195] These CS operations required by ICF indications 1323 contrast to frames 1120A-D transmitted by STA 1110 of example 1100. For example, while no CS operations are performed in example 1100 based on frames 1120A-D, STA 1312 performs CS operations on the subchannels designated by the ICF indications 1323.

[0196] In example 1300, as specified by the ICF indications 1323, CS operations are required to be performed on subchannels 1-2 used to transmit frames 1320A-B. Based on the CS operations, interference 1350 may be identified on subchannels 1-4 by STA 1312 before transmission of BA frames 1325A-D. Thus, based on the CS results for subchannels 3-4 of frames 1320C-D being idle, STA 1312 may transmit BA frames 1325C-D using the TXOP, via subchannels 3-4 of frames 1320C-D, and not transmit BA frames in response to frames 1320A-B because of the corresponding subchannels 1 -2 being subject to interference 1350.

[0197] In example 1300, after performing the CS operations required by ICF indications 1323, for the subchannels that are determined to be idle (e.g., not busy), BA frames are transmitted by STA 1312 to STA 1310, e.g., using subchannels 3-4 associated with frames 1320C-D that were determined to be idle. BA frames 1320C-D may be transmitted to STA 1310 using an HT PPDU or non-HT duplicate PPDU, e.g., as described with FIG. 10 above. In an example, BA frames 1325C-D transmitted in response to frames 1320C- D are transmitted using a primary channel and a secondary 20MHz channel The primary channel may correspond to a 20MHz channel. In alternative or additional implementations, the first STA may transmit BA frames 1325C-D via one or more secondary channels.

[0198] Continuing example 1300, after receiving BA frames 1325C-D, STA 1310 transmits data frame 1360 via subchannels 3-4 used to receive BA frames 1325C-D. After STA 1312 receives data frame 1360, STA1312 may transmit BA frames 1330C-D via subchannels 3-4 used to receive data frame 1360. In an example, data frame 1360 may be transmitted using a UHR physical layer protocol data unit (PPDU).

[0199] In example 1300, because STA 1310 did not use subchannels 1-2 subject to interference 1350 to transmit data frame 1360, a receive error for data frame 1360, similar to receive error 1 199 for data frame 1160 of FIG. 1 1 , does not occur. Thus, at least based on the foregoing, embodiments depicted with FIG. 13 may avoid the problem described above with FIG. 11 .

[0200] FIG. 14 illustrates an example 1400 of an operation that initiates of a TXOP according to an embodiment. As shown in FIG. 14, example 1400 includes a STA 1410, and a STA 1412. STA 1410 may comprise an AP STA and STA 1412 may comprise a non-AP STA. STA 1412 may be associated with STA 1410. In an implementation (not shown in FIG. 14), STA 1410 may comprise a non-AP STA, STA 1412 may comprise an AP STA, and STA 1410 may be associated with STA 1412.

[0201] As shown in FIG. 14, the operation of example 1400 that initiates a TXOP may begin with STA 1410 transmitting frames 1420A-D to STA 1412. One or more of frames 1420A-D may comprise an acknowledgement request frame. In an example, the acknowledgement request frame may comprise a BAR frame, as described with FIGS. 6 and 10 above.

[0202] In an embodiment, frames 1420A-D are transmitted on respective subchannels 1 -4 of a frequency channel bandwidth to be used for communication using the TXOP. In an implementation, the subchannels may comprise one primary 20MHz channel. The subchannels may comprise one or more secondary channels. The secondary channels may include one or more of: 20MHz channels, 40MHz channels, 80MHz 160MHz channels, and 320MHz channels. In an example, the bandwidth of the subchannels may be indicated in frames 1420A-D.

[0203] Frames 1420A-D respectively include padding bits 1424A-D. In an embodiment, padding bits 1424A-D (or the presence thereof) may be used to indicate that STA 1412 is required to perform a OS operation on subchannels within a bandwidth indicated in the frame, e.g., subchannels 1 -4 associated with the frames 1420A-D.

[0204] In an implementation, the CS operation may include at least one of a physical CS operation. The physical CS operation may include performing a clear channel assessment (CCA) on one or more of the subchannels of the bandwidth of the TXOP. The subchannels may comprise at least one of one or more 20MHz channels, one or more 40MHz channels, one or more 80MHz channels, one or more 160MHz channels, and one or more 320MHz channels.

[0205] In additional or alternative embodiments, the CS operation may include a virtual CS operation. The virtual CS operation may include MAC CS within the bandwidth of the TXOP, e.g., checking a network allocation vector (NAV) of the TXOP. In an example, frame 1420A is received on a subchannel (e.g., subchannel 1 ) that is a primary channel and frame 1420B is received on a subchannel (e.g., subchannel 2) that is a secondary subchannel, and the virtual CS operation includes checking the NAV of one or both ofthe primary and secondary subchannels. The NAVs checked by the virtual CS operation may include a basic NAV and / or an intra-BSS NAV.

[0206] Continuing example 1400, after receiving one or more of frames 1420A-D, STA 1412 initiates a TXOP for communication with STA 1410 for use of the respective subchannels 1 -4 of frames 1420A-D. After the TXOP is initiated, STA 1412 waits a duration 1466 before transmitting BA frames 1425C-D via subchannels 3-4. In an implementation, during this duration 1466, STA 1412 may perform the CS operations on subchannels 1-4 interpreted by STA 1412 as being required, e.g., based on padding bits 1424A-D (or the presence thereof). In different implementations, duration 1466 may correspond to a SIPS, may be longer than a SIPS, may be less than a PIFS, or may correspond to a PIFS.

[0207] For subchannels 1-4 depicted in example 1400, interference 1450 exists for STA 1412 for subchannels 1-2 of frames 1420A-B. In example 1400, because of padding bits 1424A-D that are interpreted by STA 1412 as requiring CS operations, during duration 1466, STA 1412 may perform CS operations on the subchannels that include subchannels 1 -4 upon which frames 1420A-D were received. Continuing example 1400, after performing the CS operations, because of interference 1450, the results of the CS operations may show that subchannels 1 -2 of frames 1420A-B are not idle (e.g., busy), while subchannels 3-4 of frames 1420C-D are idle.

[0208] In an implementation, the virtual CS will indicate busy when at least of the basic NAV and the intra- BSS NAV is non-zero. Additionally or alternatively the virtual CS may indicate busy when at least one of all NAVs that the first STA considers has NAV counter that is not equal to 0. In an alternative result, the virtual CS will indicate idle when all NAVs assessed by the CS operation have NAV counters equal to 0. In example 1400, the virtual CS may indicate idle by at least all NAVs, that the first STA (STA 1412) considers, having non-zero value.

[0209] Padding bits 1424A-D being interpreted by STA 1412 as requiring CS operations contrasts to the interpretation of frames 1120A-D by STA 1112 of example 1100. For example, while no CS operations are performed in example 1 100 based on frames 1120A-D, STA 1412 performs CS operations on subchannels 1-4 based on padding bits 1424A-D.

[0210] In example 1400, as indicated by padding bits 1424A-D, CS operations are required to be performed on subchannels 1 -4 respectively used to transmit frames 1420A-D. Based on the CS operations, interference 1450 on subchannels 1 -2 may be identified by STA 1412 before transmission of BA frames 1425A-D. Thus, based on the CS results for subchannels 3-4 of frames 1420C-D being idle, STA 1412 may transmit BA frames 1425C-D using the TXOP, via subchannels 3-4 of frames 1420C-D, and not transmit BA frames associated with frames 1420A-B because of the corresponding subchannels 1-2 being subject to interference 1450.

[0211] In example 1400, after performing the CS operations required by padding bits 1424A-D, for the subchannels that are determined to be idle (e.g., not busy), BA frames are transmitted by STA 1412 to STA1410, e.g., using subchannels 3-4 associated with frames 1420C-D that were determined to be idle. BA frames 1420C-D may be transmitted to STA 1410 using an HT PPDU or non-HT duplicate PPDU, e.g., as described with FIG 10 above. In an example, BA frames 1425C-D transmitted in response to frames 1420C- D are transmitted using a primary channel and a secondary 20MHz channel. The primary channel may correspond to a 20MHz channel. In alternative or additional implementations, the first STA may transmit BA frames 1425C-D via one or more secondary channels.

[0212] Continuing example 1400, after receiving BA frames 1425C-D, STA 1410 transmits data frame 1460 via the subchannels 3-4 used to receive BA frames 1425C-D. After STA 1412 receives data frame 1460, STA 1412 may transmit BA frames 1430C-D via subchannels 3-4 used to receive data frame 1460. In an example, data frame 1460 may be transmitted using a UHR physical layer protocol data unit (PPDU).

[0213] In example 1400, because STA 1410 did not use subchannels 1-2 subject to interference 1450 to transmit data frame 1460, a receive error for data frame 1460, similar to receive error 1 199 for data frame 1160 of FIG. 1 1 , does not occur. Thus, at least based on the foregoing, embodiments depicted with FIG. 14 may avoid the problem described above with FIG. 11 .

[0214] FIG. 15 illustrates an example process 1500 according to an embodiment. Example process 1500 is provided for the purpose of illustration only and is not limiting of embodiments. Example process 1500 may be performed by STAs such as STAs such as STA 1210, STA 1212, STA 1310, STA 1312, STA 1410, and / or STA 1412, for example. As shown in FIG. 15, process 1500 may include steps 1502 and 1504.

[0215] Step 1502 includes a first STA receiving a first frame from a second STA, with the first frame soliciting a BA frame from the first STA, and initiating a TXOP for communication between the first STA and the second STA. The first frame may comprise an acknowledgement request frame The acknowledgement request frame may comprise a BAR frame. The first frame may further comprise a field indicating that the first frame comprises the BAR frame. The first frame may comprise padding bits. The first frame may comprise a field indicating that the first frame comprises an initial control frame. The first frame may indicate whether the first STA is required to perform a CS operation during a first duration. The first frame may further comprise a field indicating that the first STA is required to perform a CS operation during a first duration.

[0216] Step 1504 includes, based on the CS operation, performed by the first STA during the first duration, indicating idle, the first STA may transmit the BA frame in response to the first frame. The CS operation may comprise a physical (PHY) CS and / or a virtual CS. The CS operation indicating idle may comprise both a PHY CS indicating idle and a virtual CS indicating idle. The PHY CS indicating idle may comprise at least a primary 20MHz channel indicating idle and / or zero or more secondary channels indicating idle. The PHY CS indicating busy may comprise a primary 20MHz channel indicating busy. The virtual CS indicating idle may comprise NAV indicating idle. The NAV indicating idle may comprise NAV indicating zero value. The NAV indicating busy may comprise NAV indicating non-zero value.

[0217] In another embodiment, the CS operation, performed by the first STA during the first duration, may indicate a busy condition. The CS operation indicating busy may comprise that at least one of the PHY CS and the virtual CS indicates busy. Based on this busy condition, instead of transmitting the BA frame in response to the first frame, the first STA does not transmit the BA frame. Because the second STA does not receive the BA frame implicated by the busy condition, the second STA does not send data based on receiving the BA frame.

[0218] The virtual CS operation may comprise checking a network allocation vector (NAV). The receiving of the first frame may comprise receiving the first frame on a first channel, and wherein the checking of the NAV comprises checking one or more respective NAV for the first channel. The first channel may comprise a primary channel. The receiving of the first frame may comprise receiving the first frame on a second channel, and wherein the checking of the NAV further comprises checking one or more respective NAV for the second channel. In an example, the second channel may comprise a secondary channel. The one or more respective NAV comprise a basic NAV and an intra-BSS NAV. The virtual CS indicates busy when at least of the basic NAV and the intra-BSS NAV is non-zero. The virtual CS indicating busy may include at least one of all NAVs that the first STA considers has NAV counter that is not equal to 0. The virtual CS indicates idle. The virtual CS indicating idle may include all NAVs that the first STA considers have their NAV counter equal to 0. The first STA transmits the BA frame using non-high throughput (HT) physical protocol data unit (PPDU) or non-HT duplicate PPDU.

[0219] In an implementation, the non-HT PPDU or non-HT duplicate PPDU is transmitted on one or more 20MHz channels where the physical CS indicates idle. The one or more 20MHz channels comprises at least primary 20MHz channel. Based on a result of the CS indicating busy, not transmitting, by the first STA to the second STA, the acknowledgement frame in response to the first frame. A secondary channel of one or more secondary channels comprises 20MHz channel(s), 40MHz channel(s), 80MHz channel(s), 160MHz channel(s).

[0220] FIG. 16 illustrates an example process 1600 according to an embodiment. Example process 1600 is provided for the purpose of illustration only and is not intended to be limiting of embodiments. Example process 1600 may be performed by STAs such as STA 1210, STA 1212, STA 1310, STA 1312, STA 1410, and / or STA 1412, for example. As shown in FIG. 16, in one embodiment process 1600 may include step 1602 and step 1604. Alternatively, process 1600 may include step 1602 and not step 1604.

[0221] Step 1602 includes transmitting, by a first station (STA) to a second station (STA), a first frame that solicits a block ack (BA) frame from the second STA and initiates a TXOP. The first frame may comprise an acknowledgement request frame. The acknowledgement request frame may comprise a BAR frame. The first frame may further comprise a field indicating that the first frame comprises the BAR frame. The first frame may comprise padding bits. The first frame may comprise a field indicating that the first frame comprises an initial control frame. The first frame may indicate whether the first STA is required to perform aCS operation during a first duration. The first frame may further comprise a field indicating that the first STA is required to perform a CS operation during a first duration.

[0222] In another embodiment, step 1602 includes transmitting, by a first STA to a second STA, a first frame: initiating a TXOP and indicating whether the second STA is required to perform a CS operation after receiving the first frame. The second STA may be configured to perform the CS operation, during a first duration after receiving the first frame, based on the indication of whether the second STA is required to perform the CS operation. The second STA may further be configured to transmit a second frame, in response to the first frame, based on the CS operation indicating idle. The first duration may comprise a short inter frame space (SIFS) duration between the first frame and the second frame. The first duration may, alternatively or in addition, comprise a second duration between the first frame and the second frame. The first frame may solicit a block ack (BA) frame from the second STA. The second frame may comprise the BA frame.

[0223] Step 1604 includes, based on a result of carrier sense (CS) operation, by the second STA during a first duration, indicating idle, transmitting, by the first STA from the second STA, the BA frame in response to the first frame. The CS operation may comprise a physical (PHY) CS and / or a virtual CS. The CS operation indicating idle may comprise both a PHY CS indicating idle and a virtual CS indicating idle. The PHY CS indicating idle may comprise at least a primary 20MHz channel indicating idle and / or zero or more secondary channels indicating idle. The PHY CS indicating busy may comprise a primary 20MHz channel indicating busy. The virtual CS indicating idle may comprise NAV indicating idle. The NAV indicating idle may comprise NAV indicating zero value. The NAV indicating busy may comprise NAV indicating non-zero value.

[0224] In another embodiment, example process 1600 does not include step 1604.

[0225] In another embodiment, the CS operation, performed by the first STA during the first duration, may indicate a busy condition. The CS operation indicating busy may comprise that at least one of the PHY CS and the virtual CS indicates busy. Based on this busy condition, instead of transmitting the BA frame in response to the first frame, the first STA does not transmit the BA frame. Because the second STA does not receive the BA frame implicated by the busy condition, the second STA does not send data based on receiving the BA frame.

[0226] The virtual CS operation may comprise checking a network allocation vector (NAV). The receiving of the first frame may comprise receiving the first frame on a first channel, and wherein the checking of the NAV comprises checking one or more respective NAV for the first channel. The first channel may comprise a primary channel. The receiving of the first frame may comprise receiving the first frame on a second channel, and wherein the checking of the NAV further comprises checking one or more respective NAV for the second channel. In an example, the second channel may comprise a secondary channel. The one or more respective NAV comprise a basic NAV and an intra-BSS NAV. The virtual CS indicates busy when at least of the basic NAV and the intra-BSS NAV is non-zero. The virtual CS indicating busy may include at least one of all NAVs that the first STA considers has NAV counter that is not equal to 0. The virtual CSindicates idle. The virtual CS indicating idle may include all NAVs that the first STA considers have their NAV counter equal to 0. The first STA transmits the BA frame using non-high throughput (HT) physical protocol data unit (PPDU) or non-HT duplicate PPDU

[0227] In an implementation, the non-HT PPDU or non-HT duplicate PPDU is transmitted on one or more 20MHz channels where the physical CS indicates idle. The one or more 20MHz channels comprises at least primary 20MHz channel. Based on a result of the CS indicating busy, not transmitting, by the first STA to the second STA, the acknowledgement frame in response to the first frame. A secondary channel of one or more secondary channels comprises 20MHz channel(s), 40MHz channel(s), 80MHz channel(s), 160MHz channel(s).

Claims

CLAIMS1. A method comprising: receiving, by a first station (STA) from a second STA, a block acknowledgement request (BAR) frame: soliciting a block acknowledgement (BA) frame from the first STA; initiating a transmit opportunity (TXOP); and indicating whether the first STA is required to perform a carrier sense (CS) operation during a short inter frame space (SIRS) duration after receiving the BAR frame; based on the BAR frame indicating that the first STA is required to perform the CS operation, performing, by the first STA, the CS operation during the SIRS duration after receiving the BAR frame; and based on a result of the CS operation indicating idle, transmitting, by the first STA to the second STA and in response to the BAR frame, the BA frame.

2. A method comprising: receiving, by a first station (STA) from a second STA, a first frame: soliciting a block ack (BA) frame from the first STA; and initiating a transmit opportunity (TXOP); and based on a result of a carrier sense (CS) operation by the first STA during a first duration, indicating idle, transmitting, by the first STA to the second STA, the BA frame in response to the first frame.

3. The method of claim 2, wherein the first frame comprises an acknowledgement request frame.

4. The method of claim 3, wherein the acknowledgement request frame comprises a block acknowledgement request (BAR) frame.

5. The method of claim 4, wherein the first frame further comprises a field indicating that the first frame comprises the BAR frame.

6. The method of claim 2, wherein the first frame comprises padding bits.

7. The method of claim 2, wherein the first frame comprises a field indicating that the first frame comprises an initial control frame.

8. The method of claim 2, wherein the first frame indicates whether the first STA is required to perform the CS operation during the first duration.

9. The method of claim 8, wherein the first frame comprises a first indication that the first STA is required to perform the CS operation during the first duration.

10. The method of claim 9, further comprising, based on the first indication, performing, by the first STA, the CS operation for the first duration.11 . The method of any of claims 2-10, wherein the first duration comprises a second duration between the receiving of the first frame and the transmitting of the BA frame.

12. The method of claim 11 , wherein the second duration comprises a short interframe space (S IFS).

13. The method of claims 2-12, wherein the CS operation comprises at least one of a physical CS operation and a virtual CS operation.

14. The method of claim 13 wherein the physical CS operation comprises performing a clear channel assessment (CCA) on one or more channels.

15. The method of claim 14, wherein the receiving of the first frame comprises receiving the first frame on one or more secondary channels, and wherein the one or more channels comprises the one or more secondary channels.

16. The method of claim 15, wherein the one or more secondary channels comprises one or more 20MHz channels, one or more 40MHz channels, one or more 80MHz channels, one or more 160MHz channels, or one or more 320MHz channels.

17. The method of claim 14, wherein the one or more channels comprises a primary 20MHz channel within a bandwidth that the first frame is sent on.

18. The method of claim 13, wherein the physical CS operation indicates idle.

19. The method of claim 13, wherein the physical CS operation indicates busy.

20. The method of claim 13, wherein the virtual CS operation comprises checking a network allocation vector (NAV).21 . The method of claim 20, wherein the receiving of the first frame comprises receiving the first frame on a first channel, and wherein the checking of the NAV comprises checking one or more respective NAV for the first channel.

22. The method of claim 21 , wherein the first channel comprises a primary channel.

23. The method of claim 21 , wherein the receiving of the first frame comprises receiving the first frame on a second channel, and wherein the checking of the NAV further comprises checking one or more respective NAV for the second channel.

24. The method of any of claims 21-22, wherein the one or more respective NAV comprise a basic NAV and an intra-BSS NAV.

25. The method of claim 24, wherein the virtual CS operation indicates busy, comprising at least one NAV that the first STA considers having a NAV counter that is not equal to 0.

26. The method of claim 13, wherein the virtual CS operation indicates idle.

27. The method of claim 26, wherein the virtual CS operation indicating idle comprises all NAVs that the first STA considers having their respective NAV counters equal to 0.

28. The method of any of claims 2-27, wherein the first STA transmits the BA frame using non-high throughput (HT) physical protocol data unit (PPDU) or non-HT duplicate PPDU.

29. The method of claim 28, wherein the non-HT PPDU or non-HT duplicate PPDU is transmitted on one or more 20MHz channels where the CS operation indicates idle.

30. The method of claim 29, wherein the one or more 20MHz channels comprises at least a primary 20MHz channel.

31. The method of any of claims 2-30, further comprising: based on a result of a CS operation by the first STA indicating busy, not transmitting, by the first STA to the second STA, an acknowledgement frame in response to a second frame, received by the first STA from the second STA, soliciting the acknowledgment frame from the first STA and initiating a TXOP.

32. A method comprising: transmitting, by a first station (STA) to a second STA, a block ack request (BAR) frame: soliciting a block ack (BA) frame from the second STA; initiating a transmit opportunity (TXOP); and indicating whether the second STA is required to perform carrier sense (CS) operation during a short inter frame space (SIPS) duration after receiving the BAR frame, wherein the second STA is configured to: perform the CS operation during the SIFS duration, based on the BAR frame indicating that the second STA is required to perform the CS operation; and transmit the BA frame, to the first STA, in response to the BAR frame and based on the CS operation indicating idle.

33. A method comprising: transmitting, by a first station (STA) to a second STA, a first frame: initiating a transmit opportunity (TXOP); and indicating whether the second STA is required to perform a carrier sense (CS) operation after receiving the first frame.

34. The method of claim 33, wherein the second STA is configured to: perform the CS operation, during a first duration after receiving the first frame, based on the indication of whether the second STA is required to perform the CS operation; and transmit a second frame, in response to the first frame, based on the CS operation indicating idle.

35. The method of claim 34, wherein the first duration comprises a short inter frame space (SIFS) duration between the first frame and the second frame.

36. The method of claim 34, wherein the first duration comprises a second duration between the first frame and the second frame.

37. The method of any of claims 34-36, wherein the first frame solicits a block ack (BA) frame from the second STA and the second frame comprises the BA frame.

38. The method of any of claims 33-37, wherein the first frame comprises an acknowledgement request frame.

39. The method of claim 38, wherein the acknowledgement request frame comprises a block ack request (BAR) frame.

40. The method of claim 39, wherein the first frame further comprises a field indicating that the first frame comprises the BAR frame.41 . The method of any of claims 33-40, wherein the first frame comprises padding bits.

42. The method of any of claims 33-41 , wherein the first frame comprises a field indicating that the first frame comprises an initial control frame.

43. The method of claims 33-42, wherein the CS operation comprises at least one of a physical CS operation and a virtual CS operation.

44. The method of claim 43, wherein the physical CS operation comprises the second STA being configured to perform a clear channel assessment (CCA) on one or more channels.

45. The method of claim 44, wherein the one or more channels comprises one or more secondary channels within a bandwidth that the first frame is sent on.

46. The method of claim 45, wherein the one or more secondary channels comprises one or more 20MHz channels, 40MHz channels, 80MHz channels, 160MHz channels, or 320MHz channels.

47. The method of claim 44, wherein the one or more channels comprises a primary 20MHz channel within a bandwidth that the first frame is sent on.

48. The method of claim 43, wherein the physical CS operation indicates idle.

49. The method of claim 43, wherein the physical CS operation indicates busy.

50. The method of claim 43, wherein the virtual CS operation indicates a network allocation vector (NAV).51 . The method of claim 50, wherein the virtual CS operation indicates idle.

52. The method of claim 50, wherein the virtual CS operation indicates busy.

53. The method of claim 33, wherein the first STA receives a block ack (BA) frame, from the second STA and in response to the first frame, using a non-high throughput (HT) physical protocol data unit (PPDU) or a non-HT duplicate PPDU.

54. The method of claim 53, wherein the second STA is configured to transmit the non-HT PPDU or non- HT duplicate PPDU on one or more 20MHz channels where the CS operation indicates idle.

55. A device comprising: one or more processors; and memory storing instructions that, when executed by the one or more processors, cause the device to perform a method according to any of claims 1-54.

56. 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-

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