Resetting the network allocation vector (NAV) after receiving an initial control frame (ICF)

Abstract

Disclosed herein is a method performed by a wireless device to reset a network allocation vector. The method includes detecting a trigger frame, setting the NAV in response to determining that the trigger frame is not addressed to the wireless device, setting a NAV timeout in response to determining that the trigger frame functions as an initial control frame as defined by a version of a wireless networking standard implemented by the wireless device or a later version wireless of the wireless networking standard, wherein the trigger frame is not a request-to-send (RTS) type frame, and resetting the NAV in response to determining that the NAV timeout has expired.

Description

SPECIFICATIONRESETTING THE NETWORK ALLOCATION VECTOR (NAV) AFTER RECEIVING AN INITIAL CONTROL FRAME (ICF)CROSS-REFERENCE TO RELATED APPLICATION

[0001] This application claims the benefit of U.S. Provisional Application No. 63 / 773,282, filed March 17, 2025, titled “Setting and Resetting the Network Allocation Vector (NAV) Timer with Initial Control Frame (ICF)”, which is hereby incorporated by reference.TECHNICAL FIELD

[0002] The present disclosure generally relates to wireless communications, and more specifically, relates to resetting a network allocation vector (NAV) after receiving an initial control frame (ICF).BACKGROUND

[0003] Institute of Electrical and Electronics Engineers (IEEE) 802.11 is a set of standards for implementing wireless local area network communication in various frequencies, including but not limited to the 2.4 gigahertz (GHz), 5 GHz, 6 GHz, and 60 GHz bands. These standards define the protocols that enable Wi-Fi devices to communicate with each other. TheIEEE 802.11 family of standards has evolved over time to accommodate higher data rates, improved security, and better performance in different environments. Some of the most widely used standards include 802.11a, 802.11b, 802.11g, 802.1 In, 802.1 lac, and 802.1 lax (also known as “Wi-Fi 6”). These standards specify the modulation techniques, channel bandwidths, and other technical aspects that facilitate interoperability between devices from various manufacturers. IEEE 802.11 has played an important role in the widespread adoption of wireless networking in homes, offices, and public spaces, enabling users to connect their devices to the internet and each other without the need for wired connections.

[0004] IEEE 802.1 Ibe, also known as “Wi-Fi 7”, is the next generation of the IEEE 802.11 family of standards for wireless local area networks. Currently under development, 802.1 Ibe aims to significantly improve upon the capabilities of its predecessor, 802.1 lax / Wi-Fi 6, by offering even higher data rates, lower latency, and increased reliability. The standard is expected to leverage advanced technologies such as multi-link operation (MLO), which allows devices to simultaneously use multiple frequency bands and channels for enhanced performance andDocket No. 1002P25007W01Client Matter No. P25-007W01reliability. Additionally, 802.11be will introduce 4096-QAM (Quadrature Amplitude Modulation), enabling higher data rates by encoding more bits per symbol. The standard will also feature improved medium access control (MAC) efficiency, enhanced power saving capabilities, and better support for high-density environments. With theseadvancements, 802.1 Ibe is expected to deliver theoretical maximum data rates of up to 46 gigabits per second (Gbps), making it suitable for bandwidth-intensive applications such as virtual and augmented reality, 8K video streaming, and high-performance gaming.

[0005] Various multi-access point (M-AP) coordination schemes are being discussed for inclusion in future wireless networking standards (e.g., IEEE 802.1 Ibn wireless networking standard (or ultra high reliability (UHR)). Such multi-AP coordination schemes include coordinated spatial reuse (co-SR or c-SR), coordinated beamforming (co-BF or c-BF), coordinated TDMA (co-TDMA or c-TDMA), and coordinated restricted target wake time (co-RTWT or c-RTWT), just to name a few examples. The use of multi-AP coordination schemes may enable more efficient use of channel resources, as well as improve throughput and latency. Multi-AP coordination may be initiated by transmitting an initial control frame (ICF).

[0006] Legacy STAs may set a network allocation vector (NAV) using the value carried in the duration / ID field when they receive a trigger frame for which they are not designated as the intended recipient. However, according to the existing wireless networking standard specification, NAV timeout (“NAVTimeouf ’) is only defined for multi-user request-to-send (MU-RTS) frames among the trigger frames that can function as an ICF. In the ongoing wireless networking standard standardization process (e.g., for UHR), the buffer status report poll (BSRP) trigger frame is being considered for use as an ICF for various purposes. As the role of the BSRP trigger frame expands to being an ICF, the NAV configuration of wireless devices that overhear the BSRP trigger frame becomes important.

[0007] Features such as multi-AP coordination are likely to set NAV for a relatively long duration. If a transmission failure occurs during the coordination frame exchange sequence, channel resources may remain idle. However, nearby devices may perceive the channel as being busy due to virtual carrier sensing based on NAV, preventing them from attempting channel access. As a result, channel resources may go unused.BRIEF DESCRIPTION OF THE DRAWINGS

[0008] The disclosure will be more fully understood from the detailed description provided below and the accompanying drawings that depict various embodiments of the disclosure.Docket No. 1002P25007W01Client Matter No. P25-007W01However, these drawings should not be interpreted as limiting the disclosure to the specific embodiments shown; they are provided for explanation and understanding only.

[0009] Figure 1 illustrates an example of a wireless local area network (WLAN) with a basic service set (BSS) that includes multiple wireless devices, in accordance with some embodiments of the present disclosure.

[0010] Figure 2 is a schematic diagram of a wireless device, in accordance with some embodiments of the present disclosure.

[0011] Figure 3 A illustrates components of a wireless device configured to transmit data, in accordance with some embodiments of the present disclosure.

[0012] Figure 3B illustrates components of a wireless device configured to receive data, in accordance with some embodiments of the present disclosure.

[0013] Figure 4 illustrates interframe space (IFS) relationships, in accordance with some embodiments of the present disclosure.

[0014] Figure 5 illustrates a Carrier Sense Multiple Access with Collision Avoidance (CSMAZCA)-based frame transmission procedure, in accordance with some embodiments of the present disclosure.

[0015] Figure 6 illustrates maximum physical layer (PHY) rates for Institute of Electrical and Electronics Engineers (IEEE) 802.11 standards, in accordance with some embodiments of the present disclosure.

[0016] Figure 7 provides a detailed description of fields in Extremely High Throughput (EHT) Physical Protocol Data Unit (PPDU) frames, including their purposes and characteristics, in accordance with some embodiments of the present disclosure.

[0017] Figure 8 illustrates an example of multi-user (MU) transmission in Orthogonal Frequency -Di vision Multiple Access (OFDMA), in accordance with some embodiments of the present disclosure.

[0018] Figure 9 illustrates an example of an access point sending a trigger frame to multiple associated stations and receiving Uplink Orthogonal Frequency-Division Multiple Access Trigger-Based Physical Protocol Data Units (UL OFDMA TB PPDUs) in response, in accordance with some embodiments of the present disclosure.

[0019] Figure 10 is a flow diagram of a method for setting the network allocation vector (NAV) timeout and resetting NAV, according to some embodiments.

[0020] Figure 11 is a diagram showing an example wireless network scenario where NAV reset can be performed, according to some embodiments.Docket No. 1002P25007W01Client Matter No. P25-007W01

[0021] Figure 12 is a flow diagram showing a method for resetting a NAV after detecting a trigger frame that functions as an initial control frame (ICF), according to some embodiments.DETAILED DESCRIPTION

[0022] The present disclosure generally relates to wireless communications, and more specifically, relates to resetting a network allocation vector (NAV) after receiving an initial control frame (ICF).

[0023] The present disclosure discloses a NAV reset rule to improve channel efficiency when a trigger frame functioning as an ICF is received / overheard. According to some embodiments, an ultra high reliability (UHR) STA may set a NAV timeout (“NAVTimeout” in IEEE 802.11 nomenclature) when it receives a trigger frame functioning as an ICF, provided that the UHR STA is not the intended recipient of the trigger frame. In IEEE 802.11 wireless networking standards, NAVTimeout refers to a time interval following reception of a PHY- RXEND. indication during which, if the STA does not receive a PHY-RXEARLYSIG.indication or PHY-RXSTART. indication from the PHY, the STA can reset its NAV. The UHR STA may reset its NAV if the NAV timeout expires (the NAV timeout duration has elapsed after receiving / overhearing the ICF) without the UHR STA receiving / overhearing a corresponding response frame (e.g., an initial control response frame (ICR)). The duration of the NAV timeout may be defined differently depending on whether the physical layer protocol data unit (PPDU) format being solicited by the trigger frame is an uplink trigger-based physical layer protocol data unit (UL TB PPDU) format or a non-HT (high throughput) PPDU format.

[0024] An embodiment is a method performed by a wireless device to reset a NAV. The method includes the steps of detecting a trigger frame, setting the NAV in response to determining that that the trigger frame is not addressed to the wireless device, setting a NAV timeout in response to determining that the trigger frame functions as an initial control frame as defined by a version of a wireless networking standard implemented by the wireless device (e.g., UHR) or a later version wireless of the wireless networking standard, wherein the trigger frame is not a request-to-send (RTS) type frame, and resetting the NAV in response to determining that the NAV timeout has expired.

[0025] With the NAV reset technique disclosed herein, if a frame exchange sequence initiated by a trigger frame functioning as an ICF unexpectedly fails, surrounding wireless devices that received the ICF (and set their NAVs) can reset their NAVs if no signal is detected in the channel for a specified period of time referred to as a NAV timeout, which allows for more efficient channel utilization.Docket No. 1002P25007W01Client Matter No. P25-007W01

[0026] For purposes of illustration, various embodiments are described herein in the context of wireless networks that are based on IEEE 802.11 standards and using terminology and concepts thereof. Those skilled in the art will appreciate that the embodiments disclosed herein can be modified / adapted for use in other types of wireless networks.

[0027] In the following detailed description, only certain embodiments of the present invention have been shown and described, simply by way of illustration. As those skilled in the art would realize, the described embodiments may be modified in different ways, all without departing from the spirit or scope of the present invention. Accordingly, the drawings and description are to be regarded as illustrative in nature and not restrictive. Like reference numerals designate like elements throughout the specification.

[0028] Figure 1 shows a wireless local area network (WLAN) 100 with a basic service set (BSS) 102 that includes a plurality of wireless devices 104 (sometimes referred to as WLAN devices 104). Each of the wireless devices 104 may include a medium access control (MAC) layer and a physical (PHY) layer according to an IEEE (Institute of Electrical and Electronics Engineers) standard 802.11, including one or more of the amendments(e.g., 802.1 la / b / g / n / p / ac / ax / bd / be). In one embodiment, the MAC layer of a wireless device 104 may initiate transmission of a frame to another wireless device 104 by passing a PHY-TXSTART. request (TXVECTOR) to the PHY layer. The TXVECTOR provides parameters for generating and / or transmitting a corresponding frame. Similarly, a PHY layer of a receiving wireless device may generate an RXVECTOR, which includes parameters of a received frame and is passed to a MAC layer for processing.

[0029] The plurality of wireless devices 104 may include a wireless device 104A that is an access point (sometimes referred to as an AP station or AP STA) and the other wireless devices 104B1-104B4 that are non-AP stations (sometimes referred to as non-AP STAs).Alternatively, all the plurality of wireless devices 104 may be non-AP STAs in an ad-hoc networking environment. In general, the AP STA (e.g., wireless device 104 A) and the non-AP STAs (e.g., wireless devices 104B1-104B4) may be collectively referred to as STAs. However, for ease of description, only the non-AP STAs may be referred to as STAs unless the context indicates otherwise. Although shown with four non-AP STAs (e.g., the wireless devices 104B1-104B4), the WLAN 100 may include any number of non-AP STAs (e.g., one or more wireless devices 104B).

[0030] Figure 2 illustrates a schematic block diagram of a wireless device 104, according to an embodiment. The wireless device 104 may be the wireless device 104A (i.e., the AP of the WLAN 100) or any of the wireless devices 104B1-104B4 in Figure 1. The wireless device 104 Docket No. 1002P25007W01Client Matter No. P25-007W01includes a baseband processor 210, a radio frequency (RF) transceiver 240, an antenna unit 250, a storage device (e.g., memory device) 232, one or more input interfaces 234, and one or more output interfaces 236. The baseband processor 210, the storage device 232, the input interfaces 234, the output interfaces 236, and the RF transceiver 240 may communicate with each other via a bus 260.

[0031] The baseband processor 210 performs baseband signal processing and includes a MAC processor 212 and a PHY processor 222. The baseband processor 210 may utilize the memory 232, which may include a non-transitory computer / machine readable medium having software (e.g., computer / machine programing instructions) and data stored therein.

[0032] In an embodiment, the MAC processor 212 includes a MAC software processing unit 214 and a MAC hardware processing unit 216. The MAC software processing unit 214 may implement a first plurality of functions of the MAC layer by executing MAC software, which may be included in the software stored in the storage device 232. The MAC hardware processing unit 216 may implement a second plurality of functions of the MAC layer in specialpurpose hardware. However, the MAC processor 212 is not limited thereto. For example, the MAC processor 212 may be configured to perform the first and second plurality of functions entirely in software or entirely in hardware according to an implementation.

[0033] The PHY processor 222 includes a transmitting (TX) signal processing unit (SPU) 224 and a receiving (RX) SPU 226. The PHY processor 222 implements a plurality of functions of the PHY layer. These functions may be performed in software, hardware, or a combination thereof according to an implementation.

[0034] Functions performed by the transmitting SPU 224 may include one or more of Forward Error Correction (FEC) encoding, stream parsing into one or more spatial streams, diversity encoding of the spatial streams into a plurality of space-time streams, spatial mapping of the space-time streams to transmit chains, inverse Fourier Transform (iFT) computation, Cyclic Prefix (CP) insertion to create a Guard Interval (GI), and the like. Functions performed by the receiving SPU 226 may include inverses of the functions performed by the transmitting SPU 224, such as GI removal, Fourier Transform computation, and the like.

[0035] The RF transceiver 240 includes an RF transmitter 242 and an RF receiver 244. The RF transceiver 240 is configured to transmit first information received from the baseband processor 210 to the WLAN 100 (e.g., to another WLAN device 104 of the WLAN 100) and provide second information received from the WLAN 100 (e.g., from another WLAN device 104 of the WLAN 100) to the baseband processor 210.Docket No. 1002P25007W01Client Matter No. P25-007W01

[0036] The antenna unit 250 includes one or more antennas. When Multiple-Input Multiple-Output (MIMO) or Multi-User MEMO (MU-MIMO) is used, the antenna unit 250 may include a plurality of antennas. In an embodiment, the antennas in the antenna unit 250 may operate as a beam-formed antenna array. In an embodiment, the antennas in the antenna unit 250 may be directional antennas, which may be fixed or steerable.

[0037] The input interfaces 234 receive information from a user, and the output interfaces 236 output information to the user. The input interfaces 234 may include one or more of a keyboard, keypad, mouse, touchscreen, microphone, and the like. The output interfaces 236 may include one or more of a display device, touch screen, speaker, and the like.

[0038] As described herein, many functions of the WLAN device 104 may be implemented in either hardware or software. Which functions are implemented in software and which functions are implemented in hardware will vary according to constraints imposed on a design. The constraints may include one or more of design cost, manufacturing cost, time to market, power consumption, available semiconductor technology, etc.

[0039] As described herein, a wide variety of electronic devices, circuits, firmware, software, and combinations thereof may be used to implement the functions of the components of the WLAN device 104. Furthermore, the WLAN device 104 may include other components, such as application processors, storage interfaces, clock generator circuits, power supply circuits, and the like, which have been omitted in the interest of brevity.

[0040] Figure 3 A illustrates components of a WLAN device 104 configured to transmit data according to an embodiment, including a transmitting (Tx) SPU (TxSP) 324, an RF transmitter 342, and an antenna 352. In an embodiment, the TxSP 324, the RF transmitter 342, and the antenna 352 correspond to the transmitting SPU 224, the RF transmitter 242, and an antenna of the antenna unit 250 of Figure 2, respectively.

[0041] The TxSP 324 includes an encoder 300, an interleaver 302, a mapper 304, an inverse Fourier transformer (IFT) 306, and a guard interval (GI) inserter 308.

[0042] The encoder 300 receives and encodes input data. In an embodiment, the encoder 300 includes a forward error correction (FEC) encoder. The FEC encoder may include a binary convolution code (BCC) encoder followed by a puncturing device. The FEC encoder may include a low-density parity-check (LDPC) encoder.

[0043] The TxSP 324 may further include a scrambler for scrambling the input data before the encoding is performed by the encoder 300 to reduce the probability of long sequences of 0s or Is. When the encoder 300 performs the BCC encoding, the TxSP 324 may further include anDocket No. 1002P25007W01Client Matter No. P25-007W01encoder parser for demultiplexing the scrambled bits among a plurality of BCC encoders. If LDPC encoding is used in the encoder, the TxSP 324 may not use the encoder parser.

[0044] The interleaver 302 interleaves the bits of each stream output from the encoder 300 to change an order of bits therein. The interleaver 302 may apply the interleaving only when the encoder 300 performs BCC encoding and otherwise may output the stream output from the encoder 300 without changing the order of the bits therein.

[0045] The mapper 304 maps the sequence of bits output from the interleaver 302 to constellation points. If the encoder 300 performed LDPC encoding, the mapper 304 may also perform LDPC tone mapping in addition to constellation mapping.

[0046] When the TxSP 324 performs a MIMO or MU-MIMO transmission, the TxSP 324 may include a plurality of interleavers 302 and a plurality of mappers 304 according to a number of spatial streams (NSS) of the transmission. The TxSP 324 may further include a stream parser for dividing the output of the encoder 300 into blocks and may respectively send the blocks to different interleavers 302 or mappers 304. The TxSP 324 may further include a space-time block code (STBC) encoder for spreading the constellation points from the spatial streams into a number of space-time streams (NSTS) and a spatial mapper for mapping the space-time streams to transmit chains. The spatial mapper may use direct mapping, spatial expansion, or beamforming.

[0047] The IFT 306 converts a block of the constellation points output from the mapper 304 (or, when MIMO or MU-MIMO is performed, the spatial mapper) to a time domain block (i.e., a symbol) by using an inverse discrete Fourier transform (IDFT) or an inverse fast Fourier transform (IFFT). If the STBC encoder and the spatial mapper are used, the IFT 306 may be provided for each transmit chain.

[0048] When the TxSP 324 performs a MIMO or MU-MIMO transmission, the TxSP 324 may insert cyclic shift diversities (CSDs) to prevent unintentional beamforming. The TxSP 324 may perform the insertion of the CSD before or after the IFT 306. The CSD may be specified per transmit chain or may be specified per space-time stream. Alternatively, the CSD may be applied as a part of the spatial mapper.

[0049] When the TxSP 324 performs a MIMO or MU-MIMO transmission, some blocks before the spatial mapper may be provided for each user.

[0050] The GI inserter 308 prepends a GI to each symbol produced by the IFT 306. Each GI may include a Cyclic Prefix (CP) corresponding to a repeated portion of the end of the symbol that the GI precedes. The TxSP 324 may optionally perform windowing to smooth edges of each symbol after inserting the GI.Docket No. 1002P25007W01Client Matter No. P25-007W01

[0051] The RF transmitter 342 converts the symbols into an RF signal and transmits the RF signal via the antenna 352. When the TxSP 324 performs a MIMO or MU-MIMO transmission, the GI inserter 308 and the RF transmitter 342 may be provided for each transmit chain.

[0052] Figure 3B illustrates components of a WLAN device 104 configured to receive data according to an embodiment, including a Receiver (Rx) SPU (RxSP) 326, an RF receiver 344, and an antenna 354. In an embodiment, the RxSP 326, RF receiver 344, and antenna 354 may correspond to the receiving SPU 226, the RF receiver 244, and an antenna of the antenna unit 250 of Figure 2, respectively.

[0053] The RxSP 326 includes a GI remover 318, a Fourier transformer (FT) 316, a demapper 314, a deinterleaver 312, and a decoder 310.

[0054] The RF receiver 344 receives an RF signal via the antenna 354 and converts the RF signal into symbols. The GI remover 318 removes the GI from each of the symbols. When the received transmission is a MIMO or MU-MIMO transmission, the RF receiver 344 and the GI remover 318 may be provided for each receive chain.

[0055] The FT 316 converts each symbol (that is, each time domain block) into a frequency domain block of constellation points by using a discrete Fourier transform (DFT) or a fast Fourier transform (FFT). The FT 316 may be provided for each receive chain.

[0056] When the received transmission is the MIMO or MU-MIMO transmission, the RxSP 326 may include a spatial demapper for converting the respective outputs of the FTs 316 of the receiver chains to constellation points of a plurality of space-time streams, and an STBC decoder for despreading the constellation points from the space-time streams into one or more spatial streams.

[0057] The demapper 314 demaps the constellation points output from the FT 316 or the STBC decoder to bit streams. If the received transmission was encoded using LDPC encoding, the demapper 314 may further perform LDPC tone demapping before performing the constellation demapping.

[0058] The deinterleaver 312 deinterleaves the bits of each stream output from the demapper 314. The deinterleaver 312 may perform the deinterleaving only when the received transmission was encoded using BCC encoding, and otherwise may output the stream output by the demapper 314 without performing deinterleaving.

[0059] When the received transmission is the MIMO or MU-MIMO transmission, the RxSP 326 may use a plurality of demappers 314 and a plurality of deinterleavers 312 corresponding to the number of spatial streams of the transmission. In this case, the RxSP 326Docket No. 1002P25007W01Client Matter No. P25-007W01may further include a stream deparser for combining the streams output from the deinterleavers 312.

[0060] The decoder 310 decodes the streams output from the deinterleaver 312 or the stream deparser. In an embodiment, the decoder 310 includes an FEC decoder. The FEC decoder may include a BCC decoder or an LDPC decoder.

[0061] The RxSP 326 may further include a descrambler for descrambling the decoded data. When the decoder 310 performs BCC decoding, the RxSP 326 may further include an encoder deparser for multiplexing the data decoded by a plurality of BCC decoders. When the decoder 310 performs the LDPC decoding, the RxSP 326 may not use the encoder deparser.

[0062] Before making a transmission, wireless devices such as wireless device 104 will assess the availability of the wireless medium using Clear Channel Assessment (CCA). If the medium is occupied, CCA may determine that it is busy, while if the medium is available, CCA determines that it is idle.

[0063] The PHY entity for IEEE 802.11 is based on Orthogonal Frequency Division Multiplexing (OFDM) or Orthogonal Frequency Division Multiple Access (OFDMA). In either OFDM or OFDMA Physical (PHY) layers, a STA (e.g., a wireless device 104) is capable of transmitting and receiving Physical Layer (PHY) Protocol Data Units (PPDUs) (also referred to as PLCP (Physical Layer Convergence Procedure) Protocol Data Units) that are compliant with the mandatory PHY specifications. A PHY specification defines a set of Modulation and Coding Schemes (MCS) and a maximum number of spatial streams. Some PHY entities define downlink (DL) and uplink (UL) Multi-User (MU) transmissions having a maximum number of space-time streams (STS) per user and employing up to a predetermined total number of STSs. A PHY entity may provide support for 10 Megahertz (MHz), 20 MHz, 40 MHz, 80 MHz, 160 MHz, 240 MHz, and 320 MHz contiguous channel widths and support for an 80+80, 80+160 MHz, and 160+160 MHz non-contiguous channel width. Each channel includes a plurality of subcarriers, which may also be referred to as tones. A PHY entity may define signaling fields denoted as Legacy Signal (L-SIG), Signal A (SIG-A), and Signal B (SIG-B), and the like within a PPDU by which some necessary information about PHY Service Data Unit (PSDU) attributes are communicated. The descriptions below, for sake of completeness and brevity, refer to OFDM-based 802.11 technology. Unless otherwise indicated, a station refers to a non-AP STA.

[0064] Figure 4 illustrates Inter-Frame Space (IFS) relationships. In particular, Figure 4 illustrates a Short IFS (SIFS), a Point Coordination Function (PCF) IFS (PIFS), a Distributed Coordination Function (DCF) IFS (DIFS), and an Arbitration IFSs corresponding to an Access Category (AC) ‘i’ (AIFS[i]). Figure 4 also illustrates a slot time and a data frame is used for Docket No. 1002P25007W01Client Matter No. P25-007W01transmission of data forwarded to a higher layer. As shown, a WLAN device 104 transmits the data frame after performing backoff if a DIFS has elapsed during which the medium has been idle.

[0065] A management frame may be used for exchanging management information, which is not forwarded to the higher layer. Subtype frames of the management frame include a beacon frame, an association request / response frame, a probe request / response frame, and an authentication request / response frame.

[0066] A control frame may be used for controlling access to the medium. Subtype frames of the control frame include a request to send (RTS) frame, a clear to send (CTS) frame, and an acknowledgement (ACK) frame.

[0067] When the control frame is not a response frame of another frame, the WLAN device 104 transmits the control frame after performing backoff if a DIFS has elapsed during which the medium has been idle. When the control frame is the response frame of another frame, the WLAN device 104 transmits the control frame after a SIFS has elapsed without performing backoff or checking whether the medium is idle.

[0068] A WLAN device 104 that supports Quality of Service (QoS) functionality (that is, a QoS STA) may transmit the frame after performing backoff if an AIFS for an associated access category (AC) (i.e., AIFS[AC]) has elapsed. When transmitted by the QoS STA, any of the data frame, the management frame, and the control frame, which is not the response frame, may use the AIFS[AC] of the AC of the transmitted frame.

[0069] A WLAN device 104 may perform a backoff procedure when the WLAN device 104 that is ready to transfer a frame finds the medium busy. The backoff procedure includes determining a random backoff time composed of N backoff slots, where each backoff slot has a duration equal to a slot time and N being an integer number greater than or equal to zero. The backoff time may be determined according to a length of a Contention Window (CW). In an embodiment, the backoff time may be determined according to an AC of the frame. All backoff slots occur following a DIFS or Extended IFS (EIFS) period during which the medium is determined to be idle for the duration of the period.

[0070] When the WLAN device 104 detects no medium activity for the duration of a particular backoff slot, the backoff procedure shall decrement the backoff time by the slot time. When the WLAN device 104 determines that the medium is busy during a backoff slot, the backoff procedure is suspended until the medium is again determined to be idle for the duration of a DIFS or EIFS period. The WLAN device 104 may perform transmission or retransmission of the frame when the backoff timer reaches zero.Docket No. 1002P25007W01Client Matter No. P25-007W01

[0071] The backoff procedure operates so that when multiple WLAN devices 104 are deferring and execute the backoff procedure, each WLAN device 104 may select a backoff time using a random function and the WLAN device 104 that selects the smallest backoff time may win the contention, reducing the probability of a collision.

[0072] Figure 5 illustrates a Carrier Sense Multiple Access / Collision Avoidance (CSMA / CA) based frame transmission procedure for avoiding collision between frames in a channel according to an embodiment. Figure 5 shows a first station STA1 transmitting data, a second station STA2 receiving the data, and a third station STA3 that may be located in an area where a frame transmitted from the STA1 can be received, a frame transmitted from the second station STA2 can be received, or both can be received. The stations STA1, STA2, and STA3 may be WLAN devices 104 of Figure 1.

[0073] The station STA1 may determine whether the channel is busy by carrier sensing. The station STA1 may determine channel occupation / status based on an energy level in the channel or an autocorrelation of signals in the channel, or may determine the channel occupation by using a network allocation vector (NAV) timer.

[0074] After determining that the channel is not used by other devices (that is, that the channel is IDLE) during a DIFS (and performing backoff if required), the station STA1 may transmit a Request-To-Send (RTS) frame to the station STA2. Upon receiving the RTS frame, after a SIFS the station STA2 may transmit a Clear-To-Send (CTS) frame as a response to the RTS frame. If Dual-CTS is enabled and the station STA2 is an AP, the AP may send two CTS frames in response to the RTS frame (e.g., a first CTS frame in a non-High Throughput format and a second CTS frame in the HT format).

[0075] When the station STA3 receives the RTS frame, it may set a NAV timer of the station STA3 for a transmission duration of subsequently transmitted frames (for example, a duration of SIFS + CTS frame duration + SIFS + data frame duration + SIFS + ACK frame duration) using duration information included in the RTS frame. When the station STA3 receives the CTS frame, it may set the NAV timer of the station STA3 for a transmission duration of subsequently transmitted frames using duration information included in the CTS frame. Upon receiving a new frame before the NAV timer expires, the station STA3 may update the NAV timer of the station STA3 by using duration information included in the new frame. The station STA3 does not attempt to access the channel until the NAV timer expires.

[0076] When the station STA1 receives the CTS frame from the station STA2, it may transmit a data frame to the station STA2 after a SIFS period elapses from a time when the CTS frameDocket No. 1002P25007W01Client Matter No. P25-007W01has been completely received. Upon successfully receiving the data frame, the station STA2 may transmit an ACK frame as a response to the data frame after a SIFS period elapses.

[0077] When the NAV timer expires, the third station STA3 may determine whether the channel is busy using the carrier sensing. Upon determining that the channel is not used by other devices during a DIFS period after the NAV timer has expired, the station STA3 may attempt to access the channel after a contention window elapses according to a backoff process.

[0078] When Dual-CTS is enabled, a station that has obtained a transmission opportunity (TXOP) and that has no data to transmit may transmit a CF-End frame to cut short the TXOP. An AP receiving a CF-End frame having a Basic Service Set Identifier (BSSID) of the AP as a destination address may respond by transmitting two more CF-End frames: a first CF-End frame using Space Time Block Coding (STBC) and a second CF-End frame using non-STBC. A station receiving a CF-End frame resets its NAV timer to 0 at the end of the PPDU containing the CF-End frame. Figure 5 shows the station STA2 transmitting an ACK frame to acknowledge the successful reception of a frame by the recipient.

[0079] The IEEE 802.1 Ibn (Ultra High Reliability, UHR) working group has been established to address the growing demand for higher peak throughput and reliability in Wi-Fi. As shown in Figure 6, the peak PHY rate has significantly increased from IEEE 802.1 lb to IEEE 802.1 Ibe (Wi-Fi 7), with the latter focusing on further improving peak throughput. The UHR study group aims to enhance the tail of the latency distribution and jitter to support applications that require low latency, such as video-over- WLAN, gaming, AR, and VR. It is noted that various characteristics of UHR (e.g., max PHY rate, PHY rate enhancement, bandwidth / number of spatial streams, and operating bands) are still to be determined.

[0080] The focus of IEEE 802.1 Ibe is primarily on WLAN indoor and outdoor operation with stationary and pedestrian speeds in the 2.4, 5, and 6 GHz frequency bands. In addition to peak PHY rate, different candidate features are under discussion. These candidate features include (1) a 320MHz bandwidth and a more efficient utilization of a non-contiguous spectrum, (2) multi -band / multi -channel aggregation and operation, (3) 16 spatial streams and Multiple Input Multiple Output (MIMO) protocol enhancements, (4) multi-Access Point (AP) Coordination (e.g., coordinated and joint transmission), (5) an enhanced link adaptation and retransmission protocol (e.g., Hybrid Automatic Repeat Request (HARQ)), and (6) adaptation to regulatory rules specific to a 6 GHz spectrum.

[0081] The focus of IEEE 802.1 Ibn (UHR) is still under discussion, with candidate features including MLO enhancements (e.g., in terms of increased throughput / reliability and decreased latency), latency and reliability improvements (e.g., multi-AP coordination to support low Docket No. 1002P25007W01Client Matter No. P25-007W01latency traffic), bandwidth expansion (e.g., to 240, 480, 640 MHz), aggregated PPDU (A-PPDU), enhanced multi-link single-radio (eMLSR) extensions to AP, roaming improvements, and power-saving schemes for prolonging battery life.

[0082] Some features, such as increasing the bandwidth and the number of spatial streams, are solutions that have been proven to be effective in previous projects focused on increasing link throughput and on which feasibility demonstration is achievable.

[0083] With respect to operational bands (e.g., 2.4 / 5 / 6 GHz) for IEEE 802.1 Ibe, more than 1 GHz of additional unlicensed spectrum is likely to be available because the 6 GHzband (5.925- 7.125 GHz) is being considered for unlicensed use. This would allow APs and STAs to become tri -band devices. Larger than 160MHz data transmissions (e.g., 320 MHz or 640 MHz) could be considered to increase the maximum PHY rate. For example, 320 MHz or 160+160MHz data could be transmitted in the 6 GHz band. For example, 160+160 MHz data could be transmitted across the 5 and 6 GHz bands.

[0084] In the process of wireless communication, a transmitting station (STA) creates a Physical Layer Protocol Data Unit (PPDU) frame and sends it to a receiving STA. The receiving STA then receives, detects, and processes the PPDU.

[0085] The Extremely High Throughput (EHT) PPDU frame encompasses several components. It includes a legacy part, which comprises fields such as the Legacy Short Training Field (L-STF), Legacy Long Training Field (L-LTF), Legacy Signal Field (L-SIG), and Repeated Legacy Signal Field (RL-SIG). These fields are used to maintain compatibility with older Wi-Fi standards.

[0086] In addition to the legacy part, the EHT PPDU frame also contains the Universal Signal Field (U-SIG), EHT Signal Field (EHT-SIG), EHT Short Training Field (EHT-STF), and EHT Long Training Field (EHT-LTF). These fields are specific to the EHT standard and are used for various purposes, such as signaling, synchronization, and channel estimation.

[0087] Figure 7 provides a more detailed description of each field in the EHT PPDU frame, including their purposes and characteristics.

[0088] Regarding the Ultra High Reliability (UHR) PPDU, its frame structure is currently undefined and will be determined through further discussions within the relevant working group or study group. This indicates that the specifics of the UHR PPDU are still under development and will be finalized based on the outcomes of future deliberations.

[0089] The distributed nature of channel access networks, such as IEEE 802.11 WLANs, makes the carrier sense mechanism useful for ensuring collision-free operation. Each station (STA) uses its physical carrier sense to detect transmissions from other STAs. However, in Docket No. 1002P25007W01Client Matter No. P25-007W01certain situations, it may not be possible for a STA to detect every transmission. For instance, when one STA is located far away from another STA, it might perceive the medium as idle and start transmitting a frame, leading to collisions. To mitigate this hidden node problem, the network allocation vector (NAV) has been introduced.

[0090] As the IEEE 802.11 standard continues to evolve, it now includes scenarios where multiple users can simultaneously transmit or receive data within a basic service set (BSS), such as uplink (UL) and downlink (DL) multi-user (MU) transmissions in a cascaded manner. In these cases, the existing carrier sense and NAV mechanisms may not be sufficient, and modifications or newly defined mechanisms may be required to facilitate efficient and collision-free operation.

[0091] For the purpose of this disclosure, MU transmission refers to situations where multiple frames are transmitted to or from multiple STAs simultaneously using different resources.Examples of these resources include different frequency resources in Orthogonal Frequency Division Multiple Access (OFDMA) transmission and different spatial streams in Multi-User Multiple Input Multiple Output (MU-MIMO) transmission. Consequently, downlink OFDMA (DL-OFDMA), downlink MU-MIMO (DL-MU-MIMO), uplink OFDMA (UL-OFDMA), uplink MU-MIMO (UL-MU-MIMO), and OFDMA with MU-MIMO are all considered examples of MU transmission.

[0092] Figure 8 illustrates an example of multi-user (MU) transmission in Orthogonal Frequency-Division Multiple Access (OFDMA), in accordance with some embodiments of the present disclosure.

[0093] In the IEEE 802.1 lax and 802.1 Ibe specifications, the trigger frame plays a useful role in facilitating uplink multi-user (MU) transmissions. The purpose of the trigger frame is to allocate resources and solicit one or more Trigger-based (TB) Physical Layer Protocol Data Unit (PPDU) transmissions from the associated stations (STAs).

[0094] The trigger frame contains information required by the responding STAs to send their Uplink TB PPDUs. This information includes the Trigger type, which specifies the type of TB PPDU expected, and the Uplink Length (UL Length), which indicates the duration of the uplink transmission.

[0095] Figure 9 illustrates an example scenario where an access point (AP) operating in an 80MHz bandwidth environment sends a Trigger frame to multiple associated STAs. Upon receiving the Trigger frame, the STAs respond by sending their respective Uplink Orthogonal Frequency Division Multiple Access (UL OFDMA) TB PPDUs, utilizing the allocated resources within the specified 80 MHz bandwidth.Docket No. 1002P25007W01Client Matter No. P25-007W01

[0096] After successfully receiving the UL OFDMA TB PPDUs, the AP acknowledges the STAs by sending an acknowledgement frame. This acknowledgement can be in the form of an 80MHz width multi-STA Block Acknowledgement (Block Ack) or a Block Acknowledgement with a Direct Feedback (DF) OFDMA method. The multi-STA Block Ack allows the AP to acknowledge multiple STAs simultaneously, while the Block Ack with DF OFDMA enables the AP to provide feedback to the STAs using the same OFDMA technique employed in the uplink transmission.

[0097] The trigger frame is a useful component in enabling efficient uplink MU transmissions in IEEE 802.1 lax and 802.1 Ibe networks, by allocating resources and coordinating the uplink transmissions from multiple STAs within the same bandwidth.

[0098] Wireless network systems can rely on retransmission of media access control (MAC) protocol data units (MPDUs) when the transmitter (TX) does not receive an acknowledgement from the receiver (RX) or MPDUs are not successfully decoded by the receiver. Using an automatic repeat request (ARQ) approach, the receiver discards the last failed MPDU before receiving the newly retransmitted MPDU. With requirements of enhanced reliability and reduced latency, the wireless network system can evolve toward a hybrid ARQ (HARQ) approach.

[0099] There are two methods of HARQ processing. In a first type of HARQ scheme, also referred to as chase combining (CC) HARQ (CC-HARQ) scheme, signals to be retransmitted are the same as the signals that previously failed because all subpackets to be retransmitted use the same puncturing pattern. The puncturing is needed to remove some of the parity bits after encoding using an error-correction code. The reason why the same puncturing pattern is used with CC-HARQ is to generate a coded data sequence with forward error correction (FEC) and to make the receiver use a maximum-ratio combining (MRC) to combine the received, retransmitted bits with the same bits from the previous transmission. For example, information sequences are transmitted in packets with a fixed length. At a receiver, error correction and detection are carried out over the whole packet. However, the ARQ scheme may be inefficient in the presence of burst errors. To solve this more efficiently, subpackets are used. In subpacket transmissions, only those subpackets that include errors need to be retransmitted.

[0100] Since the receiver uses both the current and the previously received subpackets for decoding data, the error probability in decoding decreases as the number of used subpackets increases. The decoding process passes a cyclic redundancy check (CRC) and ends when the entire packet is decoded without error or the maximum number of subpackets is reached. In particular, this scheme operates on a stop-and-wait protocol such that if the receiver can decode Docket No. 1002P25007W01Client Matter No. P25-007W01the packet, it sends an acknowledgement (ACK) to the transmitter. When the transmitter receives an ACK successfully, it terminates the HARQ transmission of the packet. If the receiver cannot decode the packet, it sends a negative acknowledgement (NAK) to the transmitter and the transmitter performs the retransmission process.

[0101] In a second type of HARQ scheme, also referred to as an incremental redundancy (IR) HARQ (IR-HARQ) scheme, different puncturing patterns are used for each subpacket such that the signal changes for each retransmitted subpacket in comparison to the originally transmitted subpacket. IR-HARQ alternatively uses two puncturing patterns for odd numbered and even numbered transmissions, respectively. The redundancy scheme of IR-HARQ improves the log likelihood ratio (LLR) of parity bit(s) in order to combine information sent across different transmissions due to requests and lowers the code rate as the additional subpacket is used. This results in a lower error rate of the subpacket in comparison to CC-HARQ. The puncturing pattern used in IR-HARQ is indicated by a subpacket identity (SPID) indication. The SPID of the first subpacket may always be set to 0 and all the systematic bits and the punctured parity bits are transmitted in the first subpacket. Self-decoding is possible when the receiving signal-to-noise ratio (SNR) environment is good (i.e., a high SNR). In some embodiments, subpackets with corresponding SPIDs to be transmitted are in increasing order of SPID but can be exchanged / switched except for the first SPID.

[0102] AP coordination has been considered as a potential technology to improve WLAN system throughput in the IEEE 802.1 Ibe standard and is still being discussed in theIEEE 802.1 Ibn (UHR) standard. To support various AP coordination schemes, such as coordinated beamforming, OFDMA, TDMA, spatial reuse, and joint transmission, a predefined mechanism for APs is necessary.

[0103] In the context of coordinated TDMA (co-TDMA or c-TDMA), the AP that obtains a transmit opportunity (TXOP) is referred to as the sharing AP. This AP initiates the AP coordination schemes to determine the AP candidate set by sending a frame, such as a Beacon frame or probe response frame, which includes information about the AP coordination scheme capabilities. The AP that participates in the AP coordination schemes after receiving the frame from the sharing AP is called the shared AP. The sharing AP is also known as the master AP or coordinating AP, while the shared AP is referred to as the slave AP or coordinated AP.Docket No. 1002P25007W01Client Matter No. P25-007W01

[0104] The operation of various AP coordination schemes has been discussed in the IEEE 802.1 Ibe and UHR standards:

[0105] Coordinated Beamforming (C-BF): Multiple APs transmit on the same frequency resource by coordinating and forming spatial nulls, allowing for simultaneous transmission from multiple APs.

[0106] Coordinated OFDMA (C-OFDMA): APs transmit on orthogonal frequency resources by coordinating and splitting the spectrum, enabling more efficient spectrum utilization.

[0107] Joint Transmission (JTX): Multiple APs transmit jointly to a given user simultaneously by sharing data between the APs.

[0108] Coordinated Spatial Reuse (C-SR): Multiple APs or STAs adjust their transmit power to reduce interference between APs.

[0109] By implementing these AP coordination schemes, WLAN systems can improve their overall throughput and efficiency by leveraging the cooperation between multiple APs.

[0110] As used herein, a UHR AP / STA may refer to an AP / STA that implements the IEEE 802.1 Ibn wireless networking standard or a later version of the wireless networking standard (that is yet to be standardized). As used herein, a legacy AP / STA may refer to an AP / STA that implements a version of a wireless networking standard that is earlier than the IEEE 802.1 Ibn (UHR) wireless networking standard. As used herein, a pre-EHT AP / STA may refer to an AP / STA that implements the IEEE 802.1 Ibe (EHT) wireless networking standard or an earlier version of the wireless networking standard. A pre-EHT AP / STA may be considered to be a legacy AP / STA in the present disclosure.

[0111] In the IEEE 802.11 wireless networking standard, an AP / STA that has obtained channel access rights can suspend the transmissions of surrounding AP / STAs for a certain duration to successfully perform and protect its transmission. To achieve this, when an AP or non-AP STA receives a frame that is not addressed to itself, it may set its NAV to allow the AP / STA that has obtained channel access rights to complete its frame exchange. NAV refers to a duration for which an AP / STA is to defer / avoid transmission.

[0112] However, there can be cases when the intended receiver of the frame transmitted by the AP / STA that acquired the channel access rights cannot respond properly. If the surrounding APs / STAs still set their NAV in such situations, the channel may remain idle and thus channel resource utilization may deteriorate. To address this issue, immediately after completing the reception of the relevant frame, each AP / STA that set their NAV may monitor the wireless medium for signals during a predefined period of time called a NAV timeout (NAVTimeout). IfDocket No. 1002P25007W01Client Matter No. P25-007W01no signal is detected during the NAV timeout period, the AP / STA may reset the previously set NAV and begin a backoff procedure to access the channel.

[0113] An ICF refers to a control frame transmitted by an AP / STA to initiate channel access. Examples of frames that can function as an ICF include a request-to-send (RTS) frame, a multiuser request-to-send (MU-RTS) trigger frame, and a buffer status report poll (BSRP) trigger frame.

[0114] Legacy APs / STAs may set their NAVs using the value carried in the duration / ID field when they receive a trigger frame for which they are not designated as the recipient. However, according to the current wireless networking standard specification, NAV timeout is only defined for the MU-RTS frame among the trigger frames that can function as an ICF. Stated differently, APs / STAs that are not the intended recipient of a MU-RTS trigger frame may reset their previously set NAVs once the NAV timeout duration has elapsed after receiving the MU-RTS trigger frame.

[0115] Starting with the IEEE 802.1 Ibe (EHT) wireless networking standard, the BSRP trigger frame is being allowed to function as an ICF to support enhanced multi-link single radio (EMLSR) functionality. However, no specific NAV timeout has been defined for the BSRP trigger frame.

[0116] In the ongoing standardization process of the IEEE 802.1 Ibn (UHR) wireless networking standard, the BSRP trigger frame is being considered for use as an ICF for various purposes. For example, the BSRP trigger frame is being considered for use as an ICF for multi-AP coordination purposes. BSRP trigger frames may potentially be used for coordinated time division multiple access (Co-TDMA), coordinated beamforming (Co-BF), coordinated spatial reuse (Co-SR), dynamic power save, dynamic unavailability operation, and non-primary channel access (NPCA), among other use cases.

[0117] As the role of the BSRP trigger frame expands to being used as an ICF, the NAV configuration of wireless devices that overhear the BSRP trigger frame becomes important. Features such as multi-AP coordination are likely to set NAV for a relatively long duration. If a transmission failure occurs during the coordination frame exchange sequence, the channel resource may remain idle. However, nearby devices may perceive the channel as being busy due to virtual carrier sensing based on NAV, preventing them from attempting channel access. As a result, channel resources may go unused. Thus, defining a NAV timeout in a way that allows the NAV to be reset in such situations can improve network efficiency. Based on this recognition, the present disclosure defines a NAV reset rule to improve channel efficiency when a trigger frame functioning as an ICF is received / overheard.Docket No. 1002P25007W01Client Matter No. P25-007W01

[0118] For convenience in this disclosure, an AP / STA that implements the IEEE 802.1 Ibn (UHR) wireless networking standard or a later version of the wireless networking standard may be referred to as a “UHR AP / STA.”

[0119] The technique disclosed herein ensures that a UHR AP / STA sets its NAV timeout only when it receives a trigger frame transmitted by another UHR AP / STA and is not designated as the intended recipient of the trigger frame. The reason for this approach is to ensure channel access fairness for APs / STAs implementing earlier versions of the wireless networking standard. The technique may decide not to set a NAV timeout when a UHR AP / STA receives a trigger frame (e.g., BSRP trigger frame) transmitted by a legacy AP / STA (e.g., a pre-EHT AP / STA). That is, NAV reset is not performed in such cases.

[0120] The rationale behind this approach is that when the transmission opportunity (TXOP) holder is a pre-EHT AP / STA, there is no defined NAV reset rule for other pre-EHT APs / STAs receiving / overhearing frames transmitted by the TXOP holder. Thus, only allowing UHR APs / STAs to reset their NAVs and gain channel access rights after the NAV timeout period in such a situation would be inappropriate from a fairness perspective.

[0121] A pre-EHT STA does not reset its NAV even if no “PHY-RXSTART. indication” primitive (indicating the start of reception) occurs after overhearing an ICF transmitted by another AP / STA, thereby limiting its channel access opportunities. Here, ICF refers to trigger frames excluding RTS and MU-RTS frames, with the BSRP trigger frame being a representative example.

[0122] However, if a UHR AP / STA receives such an ICF that is not addressed to itself and performs NAV reset based on a defined NAV reset rule, allowing it to gain channel access rights, this would be unfair to the legacy AP / STAs that are not allowed to reset their NAVs in the same way.

[0123] Thus, in an embodiment, to ensure channel access fairness, a UHR AP / STA sets its NAV timeout only when an ICF / ICR frame exchange sequence, as defined by UHR and later versions of the wireless networking standard, is not successfully completed. That is, if the TXOP holder is a UHR AP / STA, and another UHR AP / STA receives a frame transmitted by the TXOP holder UHR AP / STA that functions as an ICF, the UHR AP / STA that received the trigger frame will reset its NAV if no signal is detected in the wireless medium during the NAV timeout period.

[0124] In an embodiment, to enable NAV reset while ensuring fairness, a UHR AP / STA may set a NAV timeout for NAV reset when it receives a trigger frame transmitted by a neighboring UHR AP / STA for ICF purposes, provided it is not the intended recipient of the trigger frame. In Docket No. 1002P25007W01Client Matter No. P25-007W01general, if an AP / STA is not the intended recipient of a frame, the AP / STA sets its NAV using the value carried in the duration / ID field or the TXOP DURATION indicated in the SIGNAL field. That is, when a UHR AP / STA receives a trigger frame functioning as an ICF from another UHR AP / STA, it may set its NAV timeout and start the countdown of the NAV timeout from the time when reception ends and the channel becomes idle. However, if the UHR AP / STA receives a trigger frame from an HE or EHT AP / STA, it does not set its NAV timeout, and thus does not perform a NAV reset. For example, if a UHR AP / STA can determine from the contents of the user info field and / or common info field that the received trigger frame is a BSRP trigger frame or a bandwidth query report poll (BQRP) trigger frame transmitted by an HE or EHT AP, it does not set its NAV timeout. As an exception, if a UHR AP / STA that is not the intended recipient receives a MU-RTS trigger frame that is not in TXOP sharing mode (e.g., a MU-RTS trigger frame that is not used for TXOP sharing purposes (not a MU-RTS TXS frame)), NAV timeout mechanism is already defined in the existing wireless networking standard so the UHR AP / STA may follow the existing behavior.

[0125] Trigger frames that function as an ICF, as defined in UHR and later versions of the IEEE 802.11 wireless networking standard, may be categorized as follows. UHR and later versions define specific values for the AID 12 subfield of the user info field for particular purposes. Such specialized user info fields may be defined in UHR and later versions. For example, if the AID12 subfield is set to a value of 2008, it may have a specific meaning. As an exception, the special user info field in EHT that has an AID 12 sub field set to a value of 2007 does not fall under this category. Additionally, UHR and later versions may indicate the format of the PPDU being solicited based on specific values carried in the "GI and HE-LTF Type / TXS Mode" (GI refers to guard interval, HE-LTF refers to high efficiency long training field, and TXS refers to transmission opportunity sharing mode) subfield within the common info field. For example, if the "GI and HE-LTF Type / TXS Mode" value included in the common info field of a BSRP trigger frame is set to a value of 3, it indicates that the intended receiver of the BSRP trigger frame should respond using a non-HT PPDU format. Otherwise, the intended receiver of the BSRP trigger frame should respond using an uplink trigger-based PPDU (UL TB PPDU) format. Embodiments may use such subfield information, where available, to set an appropriate duration for the NAV timeout.

[0126] When a UHR AP / STA receives a trigger frame that is not addressed to itself, it may set its NAV timeout only if the trigger frame functions as an ICF as defined in UHR or later version of the wireless networking standard. The duration of the NAV timeout may be definedDocket No. 1002P25007W01Client Matter No. P25-007W01differently depending on whether the trigger frame solicits a UL TB PPDU format or a non-HT PPDU format.

[0127] As previously explained, the fields of the trigger frame can be examined to determine the PPDU format (e.g., UL TB PPDU format or non-HT PPDU format) that the intended recipient of the trigger frame will use to respond to the trigger frame.

[0128] In an embodiment, if it is predicted that the intended recipient of the trigger frame will respond using a UL TB PPDU format, the NAV timeout may be set as follows:

[0129] NAVTimeout = 2 x aSIFSTime + T Preamble + UL DURATION + aRxPHYStartDelay + 2 x aSlotTime

[0130] In the above equation, T Preamble refers to the preamble duration of the UL TB PPDU. UL DURATION refers to the uplink duration. UL DURATION may be calculated using the UL LENGTH value included in the trigger frame and a 6 megabits per second (Mbps) data rate. UL LENGTH may be set to the length of one QoS NULL frame or one multi-STA BA frame. Alternatively, it can be set to the aggregated length of a QoS NULL frame and a M-STA BA frame. aSIFSTime refers to the short interframe space (SIFS) duration. aSlotTime refers to a slot duration. aRxPHYStartDelay refers to the time required for the PHY (physical layer) to detect a wireless signal and trigger a Rx primitive to the MAC layer.

[0131] In an embodiment, if it is predicted that the intended recipient of the trigger frame will respond using a non-HT PPDU format, the NAV timeout may be set as follows.

[0132] NAVTimeout = 2 x aSIFSTime + BA Time + aRxPHYStartDelay + 2 x aSlotTime

[0133] In the above equation, B A Time refers to the duration of the PPDU that carries the multi-STA BA frame (including the preamble and body). BA Time may be calculated based on the length of the multi-STA BA frame and a 6 Mbps data rate. The length of the multi-STA BA frame may vary depending on the bitmap field size. Since it is difficult to accurately predict the bitmap field size, it can be estimated as having a length of 4 bytes to calculate the length. aSIFSTime, aSlotTime, and aRxPHYStartDelay can be interpreted as previously described herein for the previous equation.

[0134] In both equations provided above, since the data rate that the responder will use to transmit a response could be unknown, it can be assumed that the responder will use the lowest rate of 6 Mbps to be safe.

[0135] An example method for setting the NAV timeout and resetting NAV is shown in Figure 10.

[0136] Figure 10 is a flow diagram of a method for setting the NAV timeout and resetting NAV, according to some embodiments.Docket No. 1002P25007W01Client Matter No. P25-007W01

[0137] At operation 1002, the UHR STA may receive a trigger frame. At operation 1004, the UHR STA may determine whether it is the intended recipient of the trigger frame. If the UHR STA is the intended recipient of the trigger frame, the method may move to operation 1020, at which the UHR STA may proceed with the trigger-based response procedure and the method may end. However, if the UHR STA is not the intended recipient of the trigger frame, (e.g., if the address indicated in the receiver address (RA) field does not match the UHR STA’s address or the RA field carries a broadcast address and the UHR STA’s AID is not present in the user info field), the method may move to operation 1006, at which the UHR STA may determine whether the trigger frame functions as an ICF. If the trigger frame does not function as an ICF, the UHR STA may infer that the trigger frame was transmitted by an HE or EHT AP so the method may move to operation 1014, at which the UHR STA does not set the NAV timeout (NAVTimeout is set to zero). The method may then move to operation 1018, at which the UHR STA may set the NAV using the received duration / ID field value. Otherwise, if the trigger frame functions as an ICF, the method may move to operation 1008, at which the UHR STA may determine whether UHR / nextGen specific information is included in the trigger frame. If UHR / nextGen specific information is not included in the trigger frame, the method may move to operation 1014, at which the UHR STA does not set the NAV timeout (NAVTimeout is set to zero). The method may then move to operation 1018, at which the UHR STA may set the NAV using the received duration / ID field value. Otherwise, if UHR / nextGen specific information is included in the trigger frame, the method may move to operation 1010, at which the UHR STA may determine whether the “GI and HE-LTF Type / TXS Mode” subfield included in the common info field is set to a value of 3. If so, the method may move to operation 1016, at which the UHR STA may set the NAV timeout to “2 x aSIFSTime + BA Time + aRxPHYStartDelay + 2 x aSlotTime,” as described earlier herein. The method may then move to operation 1018, at which the UHR STA may set the NAV using the received duration / ID field value. Otherwise, if the “GI and HE-LTF Type” subfield is not set to a value of 3, the method may move to operation 1012, at which the UHR STA may set the NAV timeout to “2 x aSIFSTime + T Preamble + UL LENGTH + aRxPHYStartDelay + 2 x aSlotTime,” as described earlier herein. The method may then move to operation 1018, at which the UHR STA may set the NAV using the received duration / ID field value. If the trigger frame functions as an ICF and the “GI and HE-LTF Type / TXS Mode” field is set to a value of 3, the UHR STA may infer that the trigger frame solicits a non-HT PPDU format response. Otherwise, the UHR STA may infer that the trigger frame solicits a UL TB PPDU format response.Docket No. 1002P25007W01Client Matter No. P25-007W01

[0138] After the NAV is set at operation 1018, the method may move to operation 1022. At operation 1022, the UHR STA may determine whether the NAV timeout is set to 0. If the NAV timeout is not set to zero (NAV timeout has been set), the method may move to operation 1024. Otherwise, if NAV timeout is set to zero (NAV timeout has not been set), the method may move to operation 1038.

[0139] For the case when the NAV timeout has been set, at operation 1024, the UHR STA may countdown the NAV and the NAV timeout simultaneously. At operation 1026, the UHR STA may determine whether the NAV has expired. If the NAV has expired, the virtual carrier sense mechanism may determine that the channel is idle and the method may move to operation 1036, at which the UHR STA may proceed to a backoff procedure and the method may end. Otherwise, if the NAV has not expired, the method may move to operation 1028, at which the UHR STA may determine whether a PHY-RXEARLYSIG.indication or PHY-RXSTART.indciation (indicating the start of reception) is received from the physical layer (PHY). If such reception indication is received, the method may move to operation 1030, at which the UHR STA may proceed to the Rx (reception / receiving) procedure and the method may end. Otherwise, if such reception indication is not received, the method may move to operation 1032, at which the UHR STA may determine whether the NAV timeout has expired. If the NAV timeout has not expired, the method may move to operation 1024 to continue counting down the NAV and the NAV timeout. Otherwise, if the NAV timeout has expired, the method may move to operation 1034, at which the UHR STA may reset the NAV. The method may then move to operation 1036 at which the UHR STA proceeds to a backoff procedure and the method may end.

[0140] For the case when the NAV timeout has not been set, at operation 1038, the UHR STA may countdown the NAV. At operation 1040, the UHR STA may determine whether the NAV has expired. If the NAV has expired, the virtual carrier sense mechanism may determine that the channel is idle and the method may move to operation 1036, at which the UHR STA may proceed to backoff procedure and the method may end. Otherwise, if the NAV has not expired, the method may move to operation 1042, at which the UHR STA may determine whether a PHY-RXEARLYSIG.indication or PHY-RXSTART.indciation (indicating the start of reception) is received from the physical layer (PHY). If such reception indication is received, the method may move to operation 1030, at which the UHR STA may proceed to the Rx (reception / receiving) procedure and the method may end. Otherwise, if such reception indication is not received, the method may move to operation 1038 to continue counting down the NAV.Docket No. 1002P25007W01Client Matter No. P25-007W01

[0141] The method shown in the diagram assumes a case where the trigger frame that functions as an ICF is a BSRP frame. However, embodiments are not limited to being used with BSRP frames. The same / similar NAV timeout and NAV reset rule can be applied to BQRP (trigger) frames.

[0142] The response to a BQRP frame is defined in a same / similar manner as the response to a BSRP frame. If a BQRP frame is not aggregated with an MPDU frame that requires an immediate response, the response must include at least one QoS Null frame. If a BQRP frame is aggregated with an MPDU frame that requires an immediate response, the response may include a multi-STA BA frame.

[0143] Thus, when the trigger frame functioning as an ICF is a BQRP trigger frame, the NAV timeout may be set as follows.

[0144] NAVTimeout = 2 x aSIFSTime + T Preamble + UL DURATION + aRxPHYStartDelay + 2 x aSlotTime

[0145] In the above equation, T Preamble refers to the preamble duration of the UL TB PPDU. UL DURATION refers to the uplink duration. UL DURATION may be calculated using the UL LENGTH value included in the trigger frame and a 6 megabits per second (Mbps) data rate. UL LENGTH may be set to the length of one QoS NULL frame or one multi-STA BA frame. Alternatively, it can be set to the aggregated length of a QoS NULL frame and a M-STA BA frame. aSIFSTime, aSlotTime, and aRxPHYStartDelay can be interpreted as previously described herein for a previous equation.

[0146] The present disclosure describes a technique to improve channel utilization in situations where a frame exchange sequence initiated by a trigger frame functioning as an ICF unexpectedly fails. This is achieved by allowing surrounding APs / STAs that detect / overhear the ICF to reset their NAV if no signal is detected in the wireless channel for a NAV timeout (NAVTimeout) duration. The NAV timeout duration may be configured differently depending on the type of PPDU format being solicited by the trigger frame. By utilizing this NAV reset technique, UHR and later-generation APs / STAs can utilize channel resources more efficiently.

[0147] Figure 11 is a diagram showing an example wireless network scenario where NAV reset can be performed, according to some embodiments.

[0148] As shown in the diagram, the wireless network includes a first AP (“API”), a second AP (“AP2”), and a non-AP station (“STA1”). At operation “la,” API may transmit a trigger frame that functions as an initial control frame (ICF) to AP2. At operation “lb,” STA1 may overhear the trigger frame transmitted by API . At operation “2,” STA1 may set its NAV because the trigger frame is not addressed to STA1 (it is addressed to AP2). At operation “3,” Docket No. 1002P25007W01Client Matter No. P25-007W01STA1 may also set its NAV timeout because the trigger frame functions as an ICF. At operation “4,” STA1 may fail to overhear an initial control response frame (ICR) that corresponds to the ICF. At operation “5,” STA1 may reset its NAV if the NAV timeout expires without STA1 overhearing the ICR. STA1 may be associated with API or not associated with API - the NAV reset technique described herein is applicable to STA1 regardless of whether STA1 is associated with the transmitter of the ICF or not. While the diagram shows an example of ICF transmission between APs, embodiments are not limited to AP-to-AP ICF transmission scenarios. The NAV reset rule described herein may also be applicable in AP-to-STA ICF transmission scenarios and STA-to-AP ICF transmission scenarios.

[0149] Turning now to Figure 12, a method 1200 will be described for resetting a NAV after detecting a trigger frame that functions as an ICF, in accordance with an example embodiment. The method 1200 may be performed by a wireless device (e.g., wireless device 104).

[0150] Additionally, although shown in a particular order, in some embodiments the operations of the method 1200 may be performed in a different order. For example, although the operations of the method 1200 are shown in a sequential order, some of the operations may be performed in partially or entirely overlapping time periods.

[0151] At operation 1205, the wireless device detects a trigger frame (that is not a (MU-)RTS frame). In an embodiment, the trigger frame is a BSRP (trigger) frame or a BQRP (trigger) frame. In an embodiment, the trigger frame serves to initiate multi-AP coordination. The trigger frame may have been transmitted by an AP or a non-AP STA.

[0152] At operation 1210, the wireless device sets a NAV in response to determining that the trigger frame is not addressed to the wireless device.

[0153] At operation 1215, the wireless device determines whether the trigger frame functions as an initial control frame as defined by a version of a wireless networking standard implemented by the wireless device or a later version wireless of the wireless networking standard. If the trigger frame does not function as an initial control frame, the method may proceed to operation 1220, at which the wireless device refrains from setting a NAV timeout. However, if the trigger frame functions as an initial control frame, the method may proceed to operation 1225, at which the wireless device sets a NAV timeout. In an embodiment, the version of the wireless networking standard implemented by the wireless device is a UHR (IEEE 802.1 Ibn) wireless networking standard.

[0154] In an embodiment, the wireless device determines a duration of the NAV timeout based on a PPDU format being solicited by the trigger frame, wherein the NAV timeout is set for the determined duration of the NAV timeout. For example, when the PPDU format being Docket No. 1002P25007W01Client Matter No. P25-007W01solicited by the trigger frame is an UL TB PPDU format, the duration of the NAV timeout may be set to:

[0155] 2 x aSIFSTime + T Preamble + UL DURATION + aRxPHYStartDelay + 2 x aSlotTime, wherein aSIFSTime is a short interframe space duration, T Preamble is a preamble duration, UL DURATION is an uplink frame duration, aRxPHYStartDelay is a duration for a physical layer (PHY) to detect a wireless signal and trigger a receiver (Rx) primitive to a media access control (MAC) layer, and aSlotTime is slot duration.

[0156] When the PPDU format being solicited by the trigger frame is a non-HT PPDU format, the duration of the NAV timeout may be set to:

[0157] 2 x aSIFSTime + BA Time + aRxPHYStartDelay + 2 x aSlotTime, wherein aSIFSTime is a short interframe space duration, BA Time is a duration of the PPDU that carries the multi-STA BA frame, aRxPHYStartDelay is a duration for a physical layer to detect a wireless signal and trigger a receiver (Rx) primitive to a MAC layer, and aSlotTime is slot duration. In an embodiment, the PPDU format being solicited by the trigger frame is determined to be the non-HT PPDU format based on determining that a GI and HE-LTF type and TXS mode field included in the trigger frame carries a value of 3.

[0158] At operation 1230, the wireless device resets the NAV in response to determining that the NAV timeout has expired.

[0159] In an embodiment, the wireless device detects a second trigger frame that is not a RTS type frame and refrains from setting a NAV timeout in response to determining that the second trigger frame was transmitted by a legacy wireless device that implements an earlier version of the wireless networking standard compared to the version of the wireless networking standard implemented by the wireless device. In an embodiment, the determination that the second trigger frame was transmitted by the legacy wireless device is based on contents of a user information field (also referred to as user info field) or common information field (also referred to as common info field) included in the second trigger frame.

[0160] Although many of the solutions and techniques provided herein have been described with reference to a WLAN system, it should be understood that these solutions and techniques are also applicable to other network environments, such as cellular telecommunication networks, wired networks, etc. In some embodiments, the solutions and techniques provided herein may be or may be embodied in an article of manufacture in which a non-transitory machine-readable medium (such as microelectronic memory) has stored thereon instructions which program one or more data processing components (generically referred to here as a “processor” or “processing unit”) to perform the operations described herein. In other embodiments, some of these Docket No. 1002P25007W01Client Matter No. P25-007W01operations might be performed by specific hardware components that contain hardwired logic (e.g., dedicated digital filter blocks and state machines). Those operations might alternatively be performed by any combination of programmed data processing components and fixed hardwired circuit components.

[0161] In some cases, an embodiment may be an apparatus (e.g., an AP STA, a non-AP STA, or another network or computing device) that includes one or more hardware and software logic structures for performing one or more of the operations described herein. For example, as described herein, an apparatus may include a memory unit, which stores instructions that may be executed by a hardware processor installed in the apparatus. The apparatus may also include one or more other hardware or software elements, including a network interface, a display device, etc.

[0162] Some portions of the preceding detailed descriptions have been presented in terms of algorithms and symbolic representations of operations on data bits within a computer memory. These algorithmic descriptions and representations are the ways used by those skilled in the data processing arts to most effectively convey the substance of their work to others skilled in the art. An algorithm is here, and generally, conceived to be a self-consistent sequence of operations leading to a desired result. The operations are those requiring physical manipulations of physical quantities. Usually, though not necessarily, these quantities take the form of electrical or magnetic signals capable of being stored, combined, compared, and otherwise manipulated. It has proven convenient at times, principally for reasons of common usage, to refer to these signals as bits, values, elements, symbols, characters, terms, numbers, or the like.

[0163] It should be borne in mind, however, that all of these and similar terms are to be associated with the appropriate physical quantities and are merely convenient labels applied to these quantities. The present disclosure can refer to the action and processes of a computer system, or similar electronic computing device, that manipulates and transforms data represented as physical (electronic) quantities within the computer system's registers and memories into other data similarly represented as physical quantities within the computer system memories or registers or other such information storage systems.

[0164] The present disclosure also relates to an apparatus for performing the operations herein. This apparatus can be specially constructed for the intended purposes, or it can include a general -purpose computer selectively activated or reconfigured by a computer program stored in the computer. For example, a computer system or other data processing system may carry out the computer-implemented methods described herein in response to its processor executing a computer program (e.g., a sequence of instructions) contained in a memory or other non- Docket No. 1002P25007W01Client Matter No. P25-007W01transitory machine-readable storage medium. Such a computer program can be stored in a computer readable storage medium, such as, but not limited to, any type of disk including floppy disks, optical disks, CD-ROMs, and magnetic-optical disks, read-only memories (ROMs), random access memories (RAMs), EPROMs, EEPROMs, magnetic or optical cards, or any type of media suitable for storing electronic instructions, each coupled to a computer system bus.

[0165] The algorithms and displays presented herein are not inherently related to any particular computer or other apparatus. Various general -purpose systems can be used with programs in accordance with the teachings herein, or it can prove convenient to construct a more specialized apparatus to perform the method. The structure for a variety of these systems will appear as set forth in the description below. In addition, the present disclosure is not described with reference to any particular programming language. It will be appreciated that a variety of programming languages can be used to implement the teachings of the disclosure as described herein.

[0166] The present disclosure can be provided as a computer program product, or software, that can include a machine-readable medium having stored thereon instructions, which can be used to program a computer system (or other electronic devices) to perform a process according to the present disclosure. A machine-readable medium includes any mechanism for storing information in a form readable by a machine (e.g., a computer). In some embodiments, a machine-readable (e.g., computer-readable) medium includes a machine (e.g., a computer) readable storage medium such as a read only memory (“ROM”), random access memory (“RAM”), magnetic disk storage media, optical storage media, flash memory components, etc.

[0167] In the foregoing specification, embodiments of the disclosure have been described with reference to specific example embodiments thereof. It will be evident that various modifications can be made thereto without departing from the broader spirit and scope of embodiments of the disclosure as set forth in the following claims. The specification and drawings are, accordingly, to be regarded in an illustrative sense rather than a restrictive sense.Docket No. 1002P25007W01Client Matter No. P25-007W01

Claims

CLAIMSWhat is claimed is:

1. A method performed by a wireless device to reset a network allocation vector (NAV), the method comprising:detecting a trigger frame;setting the NAV in response to determining that that the trigger frame is not addressed to the wireless device;setting a NAV timeout in response to determining that the trigger frame functions as an initial control frame as defined by a version of a wireless networking standard implemented by the wireless device or a later version wireless of the wireless networking standard, wherein the trigger frame is not a request-to-send (RTS) type frame; andresetting the NAV in response to determining that the NAV timeout has expired.

2. The method of claim 1, wherein the version of the wireless networking standard implemented by the wireless device is an Ultra High Reliability (UHR) wireless networking standard.

3. The method of claim 1, further comprising:detecting a second trigger frame that is not a RTS type frame; andrefraining from setting a NAV timeout in response to determining that the second trigger frame was transmitted by a legacy wireless device that implements an earlier version of the wireless networking standard compared to the version of the wireless networking standard implemented by the wireless device.

4. The method of claim 3, wherein the trigger frame and the second trigger frame are buffer status report poll (BSRP) frames.

5. The method of claim 3, wherein the determination that the second trigger frame was transmitted by the legacy wireless device is based on contents of a user information field or common information field included in the second trigger frame.Docket No. 1002P25007W01Client Matter No. P25-007W016. The method of claim 1, further comprising:determining a duration of the NAV timeout based on a physical layer protocol data unit (PPDU) format being solicited by the trigger frame, wherein the NAV timeout is set for the determined duration of the NAV timeout.

7. The method of claim 6, wherein when the PPDU format being solicited by the trigger frame is an uplink trigger-based PPDU format, the duration of the NAV timeout is set to:2 x aSIFSTime + T Preamble + UL DURATION + aRxPHYStartDelay + 2 x aSlotTime,wherein aSIFSTime is a short interframe space duration, T Preamble is a preamble duration, UL DURATION is an uplink frame duration, aRxPHYStartDelay is a duration for a physical layer to detect a wireless signal and trigger a receiver (Rx) primitive to a media access control (MAC) layer, and aSlotTime is slot duration.

8. The method of claim 6, wherein when the PPDU format being solicited by the trigger frame is a non-high throughput (non-HT) PPDU format, the duration of the NAV timeout is set to:2 x aSIFSTime + BA Time + aRxPHYStartDelay + 2 x aSlotTime,wherein aSIFSTime is a short interframe space duration, BA Time is a duration of a PPDU that carries a multi-station (multi-STA) block acknowledgement frame, aRxPHYStartDelay is a duration for a physical layer to detect a wireless signal and trigger a receiver (Rx) primitive to a media access control (MAC) layer, and aSlotTime is slot duration.

9. The method of claim 8, wherein the PPDU format being solicited by the trigger frame is determined to be the non-HT PPDU format based on determining that a guard interval (GI) and high efficiency long training (HE-LTF) type and transmission opportunity sharing (TXS) mode field included in the trigger frame carries a value of 3.

10. The method of claim 1, wherein the trigger frame is a buffer status report poll (BSRP) frame or a bandwidth query report poll (BQRP) frame.

11. The method of claim 10, wherein the trigger frame initiates multi-access point (multi -AP) coordination.

12. A wireless device comprising:a radio frequency transceiver;Docket No. 1002P25007W01Client Matter No. P25-007W01a memory device storing a set of instructions; anda processor coupled to the memory device, wherein the set of instructions, when executed by the processor, causes the wireless device to perform the method of any one of claims 1-11.

13. A non-transitory machine-readable medium having computer code stored therein, which when executed by a processor of a wireless device, causes the wireless device to perform the method of any one of claims 1-11.Docket No. 1002P25007W01Client Matter No. P25-007W01

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