Preemption to support low latency (LL) data

Abstract

Disclosed herein is a method performed by an access point (AP) in a wireless network to transmit low-latency data, the method comprising: wirelessly receiving a data frame from a first station (STA) during a transmit opportunity (TXOP) of the first STA; in response to determining that the AP has low-latency data to transmit, wirelessly transmitting a block acknowledgement (BA) frame to the first STA acknowledging the data frame, the BA frame including an indication that the first STA should suspend its transmission because the AP has low-latency data to transmit; and wirelessly transmitting a low-latency data frame to a second STA following the transmission of the BA frame.

Description

[Technical Field]

[0001] [CROSS-REFERENCE TO RELATED APPLICATIONS] This application claims priority to U.S. Provisional Application No. 63 / 487,222, entitled "Preemption to Support Low-Latency (LL) Data," filed February 27, 2023; and U.S. Provisional Application No. 63 / 486,435, entitled "Preemption to Support Low-Latency (LL) Data," filed February 22, 2023, which are incorporated herein by reference. This application also claims priority to U.S. Application No. 18 / 583,475, entitled "Preemption to Support Low-Latency (LL) Data," filed February 21, 2024, which are incorporated herein by reference.

[0002] The present disclosure relates generally to wireless communications, and more particularly to the use of preemption to support low latency data transmission in wireless networks. [Background technology]

[0003] The Institute of Electrical and Electronics Engineers (IEEE) 802.11 is a set of physical and media access control (MAC) specifications for implementing wireless local area network (WLAN) communications. These specifications provide the basis for wireless networking products that use the Wi-Fi® brand, which is managed and defined by the Wi-Fi® Alliance. These specifications define the use of the 2.400-2.500 gigahertz (GHz) and 4.915-5.825 GHz spectrum bands. These spectrum bands are commonly referred to as the 2.4 GHz and 5 GHz bands. Each spectrum is subdivided into channels with a central frequency and bandwidth. The 2.4 GHz band is divided into 14 channels, each spaced 5 megahertz (MHz) apart, although some countries regulate the availability of these channels. The 5 GHz band is more tightly regulated than the 2.4 GHz band, with channel spacing varying across the spectrum and a minimum of 5 MHz spacing depending on each country or region's regulations.

[0004] WLAN devices are currently deployed in diverse environments. These environments are characterized by the presence of many access points (APs) and non-AP stations (STAs) in a limited geographical area. Increased interference from neighboring devices leads to performance degradation. In addition, WLAN devices are increasingly required to support various applications, such as video, cloud access, and offloading. In particular, video traffic is expected to become a major type of traffic in WLAN deployments. Due to the real-time requirements of some of these applications, WLAN users are demanding improved performance.

[0005] Support for low latency (LL) data is one of the key requirements for future wireless networks. For example, the scope of standards beyond IEEE 802.11be includes the delivery of low latency traffic for real-time services (e.g., virtual reality (VR), augmented reality (AR), and mixed reality (MR)). In conventional wireless networks, when a station (STA) has a transmission opportunity (TXOP) and transmits data, other devices are not allowed to initiate their own transmissions to ensure the safe transmission of the TXOP holder's data. Such an operating scenario hinders low latency transmission.

[0006] Conventional WLANs allow stations to occupy a channel or link for relatively long periods of time (e.g., by granting TXOPs to STAs) to avoid having to contend with other STAs for channel access. However, this feature of conventional WLANs makes it difficult for low-latency applications or stations to obtain channel access opportunities, which makes it difficult to meet strict latency requirements. [Brief explanation of the drawings]

[0007] The present disclosure will be more fully understood from the detailed description set forth below and from the accompanying drawings of various embodiments of the present disclosure, which drawings, however, should not be construed as limiting the disclosure to the particular embodiments, but are merely for purposes of illustration and understanding.

[0008] [Figure 1] 1 illustrates an exemplary wireless local area network (WLAN) having a basic service set (BSS) including multiple wireless devices, in accordance with some embodiments of the present disclosure.

[0009] [Figure 2] 1 is a schematic diagram of a wireless device according to some embodiments of the present disclosure.

[0010] [Figure 3] 3A and 3B illustrate components of a wireless device configured to transmit data according to some embodiments of the present disclosure.

[0011]

[0012] [Figure 4] 1 illustrates Inter-Frame Space (IFS) relationships according to some embodiments of the present disclosure.

[0013] [Figure 5] 1 illustrates a Carrier Sense Multiple Access / Collision Avoidance (CSMA / CA) based frame transmission procedure according to some embodiments of the present disclosure.

[0014] [Figure 6] 1 illustrates a table comparing various iterations of the Institute of Electrical and Electronics Engineers (IEEE) 802.11 standard, in accordance with some embodiments of the present disclosure.

[0015] [Figure 7] 1 shows a table describing fields of an Extreme High Throughput (EHT) frame format according to some embodiments of the present disclosure.

[0016] [Figure 8] A diagram illustrating a scenario in which an AP has low latency data to transmit to STAn-1 during an uplink TXOP of STA1, according to some embodiments.

[0017] [Figure 9]A diagram illustrating how an AP may preempt STA1's TXOP to transmit low-latency data, according to some embodiments.

[0018] [Figure 10] FIG. 10 illustrates the interpretation of bits B20-B23 of the U-SIG field according to some embodiments.

[0019] [Figure 11] FIG. 1 illustrates a Block ACK frame format according to some embodiments.

[0020] [Figure 12] FIG. 10 illustrates a BA control field format according to some embodiments.

[0021] [Figure 13] A diagram illustrating STA1's TXOP being extended to compensate for its TXOP being preempted, according to some embodiments.

[0022] [Figure 14] FIG. 10 illustrates STA1 extending its TXOP with a CTS to self frame, according to some embodiments.

[0023] [Figure 15] A diagram illustrating a scenario in which STAn has low-latency data to transmit to the AP during STA1's uplink TXOP, according to some embodiments.

[0024] [Figure 16] A diagram illustrating how STAn can preempt STA1's TXOP to transmit low-latency data, according to some embodiments.

[0025] [Figure 17]1 illustrates pseudocode for determining whether a STA is allowed to transmit during an (OFDMA) random access uplink transmission, according to some embodiments.

[0026] [Figure 18] A diagram illustrating STA1's TXOP being extended to compensate for its TXOP being preempted, according to some embodiments.

[0027] [Figure 19] A diagram illustrating a scenario in which a STA has low latency data to transmit to an AP during the AP's downlink TXOP, according to some embodiments.

[0028] [Figure 20] A diagram illustrating how a STAn may preempt an AP's TXOP to transmit low-latency data, according to some embodiments.

[0029] [Figure 21] FIG. 10 illustrates an AP's TXOP being extended to compensate for its preemption, according to some embodiments.

[0030] [Figure 22] 1 is a flow diagram illustrating a method performed by an AP to transmit low latency data during a TXOP of a first STA, according to some embodiments.

[0031] [Figure 23] 1 is a flow diagram illustrating a method performed by a first STA to allow an AP to transmit low latency data, according to some embodiments.

[0032] [Figure 24] 1 is a flow diagram illustrating a method performed by a first STA to allow other STAs to transmit low latency data during the first STA's TXOP, according to some embodiments.

[0033] [Figure 25] 1 is a flow diagram illustrating a method performed by a first STA to transmit low latency data during a TXOP of a second STA, according to some embodiments.

[0034] [Figure 26] 1 is a flow diagram illustrating a method performed by a first STA to determine whether to transmit low latency data wirelessly to an AP during a random access uplink wireless transmission, according to some embodiments.

[0035] [Figure 27] 1 is a flow diagram illustrating a method performed by an AP to allow a STA to transmit low latency data during the AP's TXOP, according to some embodiments.

[0036] [Figure 28] 1 is a flow diagram illustrating a method performed by a first STA to allow a second STA to transmit low latency data during a TXOP of an AP, according to some embodiments.

[0037] [Figure 29] 1 is a flow diagram illustrating a method performed by a first STA to transmit low latency data during a TXOP of an AP, according to some embodiments. DETAILED DESCRIPTION OF THE INVENTION

[0038] One aspect of the present disclosure relates generally to wireless communications, and more particularly to enabling low latency (LL) data transmission using preemption in wireless networks.

[0039] Some embodiments allow an access point (AP) to transmit low-latency data in the middle of a station (STA)'s transmission opportunity (TXOP) by preempting the STA's TXOP. The STA's TXOP may be extended to compensate for the loss of the TXOP due to the preemption. Some embodiments also allow a first STA to transmit low-latency data in the middle of a second STA's TXOP by preempting a second STA's TXOP. The second STA's TXOP may be extended to compensate for the loss of the TXOP due to the preemption. Some embodiments also allow a STA to transmit low-latency data in the middle of an AP's TXOP by preempting an AP's TXOP. The AP's TXOP may be extended to compensate for the loss of the TXOP due to the preemption.

[0040] For purposes of illustration, various embodiments are described herein in the context of, and using the terminology and concepts of, a wireless network based on the IEEE 802.11 standard. Those skilled in the art will understand that the embodiments disclosed herein may be modified / adapted for use in other types of wireless networks.

[0041] In the following detailed description, only certain embodiments of the invention are shown and described by way of example only. As those skilled in the art will recognize, the described embodiments can be modified in various different ways, all without departing from the spirit or scope of the invention. Accordingly, the drawings and descriptions are to be regarded as illustrative in nature and not restrictive. Like reference numerals designate like elements throughout the specification.

[0042] FIG. 1 illustrates a wireless local area network (WLAN) 100 having a basic service set (BSS) 102 including multiple 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 conforming to the Institute of Electrical and Electronics Engineers (IEEE) standard 802.11, including one or more of its revisions (e.g., 802.11a / 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 the corresponding frame. Similarly, the PHY layer of a receiving wireless device may generate an RXVECTOR containing parameters of the received frame and passed to the MAC layer for processing.

[0043] The multiple wireless devices 104 may include wireless device 104A, which is an access point (sometimes referred to as an AP station or AP STA), and other wireless devices 104B1-104B4, which are non-AP stations (sometimes referred to as non-AP STAs). Alternatively, all of the multiple wireless devices 104 may be non-AP STAs in an ad-hoc networking environment. In general, AP STAs (e.g., wireless device 104A) and non-AP STAs (e.g., wireless devices 104B1-104B4) may be collectively referred to as STAs. However, for ease of explanation, only non-AP STAs may be referred to as STAs. Although shown with four non-AP STAs (e.g., wireless devices 104B1-104B4), WLAN 100 may include any number of non-AP STAs (e.g., one or more wireless devices 104B).

[0044] 2 shows a schematic block diagram of a wireless device 104 according to one embodiment. The wireless device 104 may be the wireless device 104A (i.e., an AP of the WLAN 100) or any of the wireless devices 104B1-104B4 in FIG. 1. The wireless device 104 includes a baseband processor 210, a radio frequency (RF) transceiver 240, an antenna unit 250, a storage device (e.g., a 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 interface 234, the output interface 236, and the RF transceiver 240 may communicate with each other via a bus 260.

[0045] 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 memory 232, which may include a non-transitory computer / machine readable medium having software (e.g., computer / machine programming instructions) and data stored therein.

[0046] In one embodiment, MAC processor 212 includes a MAC software processing unit 214 and a MAC hardware processing unit 216. 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 software stored on storage device 232. MAC hardware processing unit 216 may implement a second plurality of functions of the MAC layer in dedicated hardware. However, MAC processor 212 is not so limited. For example, MAC processor 212 may be configured to perform the first and second plurality of functions entirely in software or entirely in hardware, depending on the implementation.

[0047] The PHY processor 222 includes a transmitting (TX) signal processing unit (SPU) 224 and a receiving (RX) SPU 226. The PHY processor 222 implements several functions of the PHY layer, which may be performed in software, hardware, or a combination thereof, depending on the implementation.

[0048] The 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 multiple space-time streams, spatial mapping of the space-time streams to the transmit chains, inverse Fourier Transform (iFT) calculation, Cyclic Prefix (CP) insertion to create a Guard Interval (GI), and the like. The functions performed by the receiving SPU 226 may include the inverse of the functions performed by the transmitting SPU 224, such as GI removal, Fourier Transform calculation, and the like.

[0049] 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 in the WLAN 100) and to provide second information received from the WLAN 100 (e.g., from another WLAN device 104 in the WLAN 100) to the baseband processor 210.

[0050] Antenna unit 250 includes one or more antennas. If Multiple-Input Multiple-Output (MIMO) or Multi-User MIMO (MU-MIMO) is used, antenna unit 250 may include multiple antennas. In one embodiment, the antennas in antenna unit 250 may operate as a beamforming antenna array. In one embodiment, the antennas in antenna unit 250 may be directional antennas, which may be fixed or steerable.

[0051] The input interface 234 receives information from a user, and the output interface 236 outputs information to a user. The input interface 234 may include one or more of a keyboard, a keypad, a mouse, a touch screen, a microphone, and the like. The output interface 236 may include one or more of a display device, a touch screen, a speaker, and the like.

[0052] 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 depend on design constraints. Such constraints may include one or more of design cost, manufacturing cost, time to market, power consumption, available semiconductor technology, etc.

[0053] 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. Additionally, the WLAN device 104 may include other components, such as an application processor, a storage interface, clock generator circuits, power supply circuits, and the like, which have been omitted for the sake of brevity.

[0054] 3A illustrates components of a WLAN device 104 configured to transmit data, according to one embodiment, including a transmitting (Tx) SPU (TxSP) 324, an RF transmitter 342, and an antenna 352. In one embodiment, TxSP 324, RF transmitter 342, and antenna 352 correspond to transmitting SPU 224, RF transmitter 242, and antennas of antenna unit 250, respectively, of FIG.

[0055] 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 .

[0056] The encoder 300 receives and encodes input data. In one 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.

[0057] TxSP 324 may further include a scrambler to scramble input data before encoding is performed by encoder 300 to reduce the probability of long sequences of 0s or 1s. If encoder 300 performs BCC encoding, TxSP 324 may further include an encoder parser to demultiplex the scrambled bits among multiple BCC encoders. If LDPC coding is used in the encoder, TxSP 324 may not use an encoder parser.

[0058] The interleaver 302 interleaves the bits of each stream output from the encoder 300 to change the order of the bits therein. The interleaver 302 may apply interleaving only if the encoder 300 performs BCC encoding; otherwise, the interleaver 302 may output the stream output from the encoder 300 without changing the order of the bits therein.

[0059] The mapper 304 maps the sequence of bits output from the interleaver 302 to constellation points. If the encoder 300 performs LDPC coding, the mapper 304 may also perform LDPC tone mapping in addition to constellation mapping.

[0060] If the TxSP 324 performs MIMO or MU-MIMO transmission, the TxSP 324 may include multiple interleavers 302 and multiple mappers 304 depending on the number of spatial streams (NSS) of the transmission. The TxSP 324 may further include a stream parser to divide the output of the encoder 300 into blocks and send the blocks to different interleavers 302 or mappers 304, respectively. The TxSP 324 may also include a space-time block code (STBC) encoder to unpack constellation points from the spatial streams into the number of space-time streams (NSTS), and a spatial mapper to map the space-time streams to the transmit chains. The spatial mapper may use direct mapping, spatial spreading, or beamforming.

[0061] The IFT 306 converts the blocks of constellation points output by the mapper 304 (or the spatial mapper if MIMO or MU-MIMO is implemented) into time-domain blocks (i.e., symbols) by using an inverse discrete Fourier transform (IDFT) or an inverse fast Fourier transform (IFFT). If an STBC encoder and spatial mapper are used, an IFT 306 may be provided for each transmit chain.

[0062] If the TxSP 324 performs MIMO or MU-MIMO transmission, the TxSP 324 may insert cyclic shift diversity (CSD) to prevent unintentional beamforming. The TxSP 324 may perform CSD insertion before or after the IFT 306. CSD may be specified per transmit chain or per space-time stream. Alternatively, CSD may be applied as part of the spatial mapper.

[0063] If the TxSP 324 performs MIMO or MU-MIMO transmission, several blocks may be provided for each user before the spatial mapper.

[0064] The GI inserter 308 prepends a GI to each symbol generated by the IFT 306. Each GI may include a cyclic prefix (CP) that corresponds to the repeated portion of the trailing end of the symbol that the GI precedes. The TxSP 324 may optionally perform windowing to smooth the edges of each symbol after inserting the GI.

[0065] The RF transmitter 342 converts the symbols into an RF signal and transmits the RF signal via an antenna 352. If the TxSP 324 performs MIMO or MU-MIMO transmission, a GI inserter 308 and an RF transmitter 342 may be provided for each transmit chain.

[0066] 3B illustrates components of WLAN device 104 configured to receive data, according to one embodiment, including a receiver (Rx) SPU (RxSP) 326, an RF receiver 344, and an antenna 354. In one embodiment, RxSP 326, RF receiver 344, and antenna 354 may correspond to receiving SPU 226, RF receiver 244, and antenna of antenna unit 250, respectively, of FIG.

[0067] The RxSP 326 includes a GI remover 318 , a Fourier transformer (FT) 316 , a demapper 314 , a deinterleaver 312 , and a decoder 310 .

[0068] The RF receiver 344 receives an RF signal via an antenna 354 and converts the RF signal into symbols. The GI remover 318 removes the GI from each of the symbols. If the received transmission is a MIMO or MU-MIMO transmission, an RF receiver 344 and a GI remover 318 may be provided for each receive chain.

[0069] The FT 316 transforms each symbol (i.e., 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). A FT 316 may be provided for each receive chain.

[0070] If the received transmission is a MIMO or MU-MIMO transmission, the RxSP326 may include a spatial demapper for converting the output of each of the FTs316 in the receive chain into constellation points for multiple space-time streams, and an STBC decoder for despreading the constellation points from the space-time streams into one or more spatial streams.

[0071] The demapper 314 demaps the constellation points output from the FT 316 or STBC decoder into a bitstream. If the received transmission was coded using LDPC coding, the demapper 314 may further perform LDPC tone demapping before performing constellation demapping.

[0072] Deinterleaver 312 deinterleaves the bits of each stream output from demapper 314. Deinterleaver 312 may perform deinterleaving only if the received transmission was coded using BCC coding; otherwise, it may output the streams output by demapper 314 without performing deinterleaving.

[0073] If the received transmission is a MIMO or MU-MIMO transmission, the RxSP 326 may use multiple demappers 314 and multiple deinterleavers 312 corresponding to the number of spatial streams of the transmission. In this case, the RxSP 326 may further include a stream deparser to combine the streams output from the deinterleavers 312.

[0074] The decoder 310 decodes the stream output from the deinterleaver 312 or stream deparser. In one embodiment, the decoder 310 includes an FEC decoder. The FEC decoder may include a BCC decoder or an LDPC decoder.

[0075] The RxSP 326 may further include a descrambler for descrambling the decoded data. If the decoder 310 performs BCC decoding, the RxSP 326 may further include an encoder deparser for multiplexing data decoded by multiple BCC decoders. If the decoder 310 performs LDPC decoding, the RxSP 326 may not use an encoder deparser.

[0076] Before transmitting, a wireless device, such as wireless device 104, will assess the availability of the wireless medium using Clear Channel Assessment (CCA). If the medium is occupied, the CCA may determine that it is in a busy state, while if the medium is available, the CCA determines that it is in an idle state.

[0077] PHY entities for IEEE 802.11 are based on Orthogonal Frequency Division Multiplexing (OFDM) or Orthogonal Frequency Division Multiple Access (OFDMA). At either the OFDM or OFDMA physical (PHY) layer, a STA (e.g., wireless device 104) can transmit and receive PHY Protocol Data Units (PPDUs) that conform to the required PHY specification. The PHY specification defines a set of modulation and coding schemes (MCSs) and a maximum number of spatial streams. Some PHY entities have a maximum number of space-time streams (STSs) per user and define downlink (DL) and uplink (UL) multi-user (MU) transmissions employing up to a predetermined total number of STSs. The PHY entity may provide support for contiguous channel widths of 10 megahertz (MHz), 20 MHz, 40 MHz, 80 MHz, 160 MHz, 240 MHz, and 320 MHz, and non-contiguous channel widths of 80 + 80, 80 + 160 MHz, and 160 + 160 MHz. Each channel includes multiple subcarriers, which may also be referred to as tones. The PHY entity may define signaling fields within the PPDU, denoted as Legacy Signal (L-SIG), Signal A (SIG-A), and Signal B (SIG-B), and the like, which convey some necessary information regarding PHY Service Data Unit (PSDU) attributes. For completeness and brevity, the following description refers to OFDM-based 802.11 technology. Unless otherwise indicated, station refers to a non-AP STA.

[0078] Figure 4 illustrates interframe spacing (IFS) relationships. In particular, Figure 4 illustrates the Short IFS (SIFS), Point Coordination Function (PCF) IFS (PIFS), Distributed Coordination Function (DCF) IFS (DIFS), and Arbitration IFS (AIFS[i]) corresponding to Access Category (AC) "i." Figure 4 also illustrates slot times, in which data frames are used for transmission of data forwarded to higher layers. As shown, the WLAN device 104 transmits a data frame after performing a backoff if the DIFS has elapsed while the medium is idle.

[0079] Management frames can be used to exchange management information that is not forwarded to higher layers. Subtypes of management frames include beacon frames, association request / response frames, probe request / response frames, and authentication request / response frames.

[0080] Control frames may be used to control access to the medium. Subtypes of control frames include request to send (RTS) frames, clear to send (CTS) frames, and acknowledgement (ACK) frames.

[0081] When the control frame is not a response frame of another frame, the WLAN device 104 transmits the control frame after performing a backoff if a DIFS has elapsed while the medium is idle. When the control frame is a response frame of another frame, the WLAN device 104 transmits the control frame after a SIFS has elapsed without performing a backoff or checking whether the medium is idle.

[0082] A WLAN device 104 that supports Quality of Service (QoS) functionality (i.e., a QoS STA) may transmit a frame after performing a backoff if the AIFS (i.e., AIFS[AC]) for the associated Access Category (AC) has elapsed. When transmitted by a QoS STA, data frames, management frames, and control frames that are not response frames may use the AIFS[AC] of the AC of the transmitted frame.

[0083] If a WLAN device 104 ready to transmit a frame finds the medium busy, the WLAN device 104 may perform a backoff procedure. The backoff procedure includes determining a random backoff time consisting of N backoff slots, where each backoff slot has a time length equal to the slot time, and N is an integer greater than or equal to zero. The backoff time may be determined as a function of the length of the contention window (CW). In one embodiment, the backoff time may be determined as a function of the 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 length of that period.

[0084] If the WLAN device 104 detects no medium activity for the length of a particular backoff slot, the backoff procedure must decrement the backoff time by the slot time. If the WLAN device 104 determines that the medium is busy during the backoff slot, the backoff procedure is paused until the medium is again determined to be idle for the length of a DIFS or EIFS period. If the backoff timer reaches zero, the WLAN device 104 may transmit or retransmit the frame.

[0085] The backoff procedure operates such that when multiple WLAN devices 104 refrain from transmitting and perform the backoff procedure, each WLAN device 104 can select a backoff time using a random function, and the WLAN device 104 that selects the shortest backoff time can win the contention, reducing the probability of collision.

[0086] 5 illustrates a carrier sense multiple access / collision avoidance (CSMA / CA)-based frame transmission procedure for avoiding collisions between frames within a channel, according to one embodiment. Figure 5 illustrates a first station STA1 transmitting data, a second station STA2 receiving the data, and a third station STA3, which may be located within an area where a frame transmitted from STA1 can be received, a frame transmitted from the second station STA2 can be received, or both can be received. Stations STA1, STA2, and STA3 may be WLAN devices 104 of FIG. 1.

[0087] Station STA1 may determine whether the channel is busy by carrier sensing, may determine channel occupancy / status based on the energy level in the channel or autocorrelation of the signal in the channel, or may determine channel occupancy by using a network allocation vector (NAV) timer.

[0088] After determining that the channel is not being used by other devices (i.e., the channel is idle) during a DIFS (and performing a backoff if necessary), station STA1 may transmit a request to send (RTS) frame to station STA2. Upon receiving the RTS frame, after a SIFS, station STA2 may transmit a clear to send (CTS) frame in response to the RTS frame. If dual CTS is enabled and station STA2 is an AP, the AP may transmit two CTS frames in response to the RTS frame (e.g., the first CTS frame is in a non-high throughput format and the second CTS frame is in an HT format).

[0089] When station STA3 receives an RTS frame, it may use the time length information included in the RTS frame to set its NAV timer for the transmission time length of a subsequently transmitted frame (e.g., the time length of SIFS+CTS frame time length+SIFS+data frame time length+SIFS+ACK frame time length). When station STA3 receives a CTS frame, it may use the time length information included in the CTS frame to set its NAV timer for the transmission time length of a subsequently transmitted frame. If station STA3 receives a new frame before the NAV timer expires, it may update its NAV timer by using the time length information included in the new frame. Station STA3 will not attempt to access the channel until the NAV timer expires.

[0090] When station STA1 receives a CTS frame from station STA2, it may transmit a data frame to station STA2 after a SIFS period has elapsed since the CTS frame was completely received. Upon successfully receiving the data frame, station STA2 may transmit an ACK frame in response to the data frame after a SIFS period has elapsed.

[0091] If the NAV timer expires, the third station STA3 may use carrier sensing to determine whether the channel is busy. If the station STA3 determines that the channel is not being used by another device during the DIFS period after the NAV timer expires, the station STA3 may follow a backoff process and attempt to access the channel after the contention window has elapsed.

[0092] When Dual CTS is enabled, a station that has a transmit opportunity (TXOP) but has no data to send may transmit a CF-End frame to shorten the TXOP. An AP that receives a CF-End frame with the AP's Basic Service Set Identifier (BSSID) as the destination address may respond by transmitting two more CF-End frames: one using Space Time Block Coding (STBC) and one using non-STBC. A station that receives a CF-End frame resets its NAV timer to 0 at the end of the PPDU containing the CF-End frame. Figure 5 shows station STA2 transmitting an ACK frame to acknowledge successful reception of the frame by the receiver.

[0093] With a clear demand for higher peak throughput / capacity in WLANs, a new working group was formed to create an amendment to IEEE 802.11. This amendment, called IEEE 802.11be (i.e., Extremely High Throughput (EHT)), was created to support corresponding WLAN peak PHY speed improvements. Considering IEEE 802.11b through 802.11ac, the peak PHY speed has increased by 5x to 11x, as shown in Figure 6, which presents a table 600 comparing various iterations of IEEE 802.11. In the case of IEEE 802.11ax, the 802.11ax working group focuses on improving efficiency rather than peak PHY speed in high-density environments. The maximum PHY speed (A Gbps) and PHY speed improvement (Bx) for IEEE 802.11be may depend on the highest MCS (e.g., 4096QAM and its coding rate).

[0094] IEEE 802.11be primarily focuses on indoor and outdoor operation of WLANs at stationary and walking speeds in the 2.4, 5, and 6 GHz frequency bands. In addition to peak PHY speeds, different candidate features are being discussed. These candidate features include (1) more efficient utilization of 320 MHz bandwidth and non-contiguous spectrum, (2) multi-band / multi-channel aggregation and operation, (3) 16 spatial stream and multiple-input multiple-output (MIMO) protocol enhancements, (4) multi-access point (AP) coordination (e.g., coordinated transmission and joint transmission), (5) enhanced link adaptation and retransmission protocols (e.g., hybrid automatic repeat request (HARQ)), and (6) compliance with regulatory rules specific to the 6 GHz spectrum.

[0095] Some features, such as increasing bandwidth and the number of spatial streams, have proven effective in previous projects focused on improving link throughput, and demonstration of feasibility is an achievable solution.

[0096] With the 6 GHz band (5.925-7.125 GHz) being considered for unlicensed use in relation to the operating bands for IEEE 802.11be (e.g., 2.4 / 5 / 6 GHz), additional unlicensed spectrum above 1 GHz is likely to become available. This would allow APs and STAs to become tri-band devices. Data transmission greater than 160 MHz (e.g., 320 MHz) may be considered to improve maximum PHY speeds. For example, 320 MHz or 160+160 MHz data may be transmitted in the 6 GHz band. For example, 160+160 MHz data may be transmitted across the 5 GHz and 6 GHz bands.

[0097] In some embodiments, a transmitting STA generates a PPDU frame and transmits it to a receiving STA. The receiving STA receives, detects, and processes the PPDU. The PPDU may be an EHT PPDU that includes a legacy portion (e.g., a legacy short training field (L-STF), a legacy long training field (L-LTF), and a legacy signal (L-SIG) field), an EHT signal A field (EHT-SIG-A), an EHT signal B field (EHT-SIG-B), an EHT hybrid automatic repeat request (EHT-HARQ), an EHT short training field (EHT-STF), an EHT long training field (EHT-LTF), and an EHT-DATA field. Figure 7 includes a table 700 describing the fields of an EHT frame format. In particular, table 700 describes the various fields that may be present in the PHY preamble, data field, and midamble of an EHT frame format.For example, table 700 includes a legacy short training field (L-STF) 712, a legacy long training field (L-LTF) 714, a legacy signal field (L-SIG) 716, a repeated L-SIG (RL-SIG) 718, a universal signal field (U-SIG) 720, an EHT signal field (EHT-SIG) 722, an EHT hybrid automatic repeat request field (EHT-HARQ) 724, an EHT short training field (EHT-STF) 726, an EHT long training field (EHT-LTF) 728, an EHT data field 730, and an EHT midamble field. 7 includes a definition 702 for one or more of the EHT-MA field 732, a time length 704, a Discrete Fourier Transform (DFT) period 706, a Guard Interval (GI) 708, and a subcarrier spacing 710.

[0098] The distributed nature of channel access networks, such as IEEE 802.11 wireless networks, makes carrier sensing mechanisms important for collision-free operation. A STA's physical carrier sensing mechanism is responsible for detecting other STAs' transmissions. However, in some situations, it may be impossible to detect every single case. For example, a STA, which may be located a long distance away from another STA, may consider the medium to be idle and begin transmitting a frame while the other STA is also transmitting. To overcome this hidden node, a network allocation vector (NAV) may be used. However, as wireless networks evolve to include simultaneous transmission / reception between multiple users within a single basic service set (BSS), such as uplink (UL) / downlink (DL) multi-user (MU) transmissions in a cascaded manner, mechanisms to enable such situations may be necessary. As used herein, multi-user (MU) transmission refers to the case where multiple frames are transmitted simultaneously to or from multiple STAs using different resources. Examples of different resources are different frequency resources in OFDMA transmissions and different spatial streams in MU-MIMO transmissions. Thus, DL-OFDMA, DL-MU-MIMO, UL-OFDMA, and UL-MU-MIMO are examples of MU transmission.

[0099] Wireless network systems may rely on retransmission of a Medium Access Control (MAC) protocol data unit (MPDU) if the transmitter (TX) does not receive an acknowledgment from the receiver (RX) or if the MPDU is not successfully decoded by the receiver. Using an Automatic Repeat Request (ARQ) scheme, the receiver discards the last failed MPDU before receiving the newly retransmitted MPDU. With requirements for increased reliability and reduced delay, wireless network systems may evolve to a Hybrid ARQ (HARQ) scheme.

[0100] There are two methods for HARQ processing. In the first type of HARQ scheme, also known as chase combining (CC) HARQ (CC-HARQ), all subpackets to be retransmitted use the same puncturing pattern, so that the retransmitted signal is the same as the previously failed signal. Puncturing is necessary to remove some of the parity bits after encoding with an error-correcting code. The reason for using the same puncturing pattern in CC-HARQ is that it generates a coded data sequence using forward error correction (FEC) and the receiver combines the received retransmitted bits with the same bits from the previous transmission using maximum-ratio combining (MRC). For example, an information sequence is transmitted in packets with a fixed length. At the receiver, error correction and detection are performed across the entire packet. However, ARQ schemes can be inefficient in the presence of burst errors. To solve this problem more efficiently, subpackets are used. In subpacket transmission, only erroneous subpackets need to be retransmitted.

[0101] Because the receiver uses both the current and previously received subpackets to decode the data, the error probability in decoding decreases as the number of subpackets used increases. The decoding process terminates when a cyclic redundancy check (CRC) passes and the entire packet is decoded without errors or the maximum number of subpackets is reached. In particular, this scheme operates in a stop-and-wait protocol, such that if the receiver can decode the packet, it sends an acknowledgment (ACK) to the transmitter. If the transmitter successfully receives the ACK, it terminates the HARQ transmission of the packet. If the receiver cannot decode the packet, it sends a negative acknowledgment (NAK) to the transmitter, and the transmitter performs a retransmission process.

[0102] In a second type of HARQ scheme, also known as incremental redundancy (IR) HARQ (IR-HARQ), a different puncturing pattern is used for each subpacket so that the signal changes for each retransmitted subpacket compared to the originally transmitted subpacket. IR-HARQ alternates between two puncturing patterns for odd-numbered and even-numbered transmissions. The redundancy scheme of IR-HARQ improves the log likelihood ratio (LLR) of the parity bits to combine information sent across different transmissions due to requests, and reduces the coding rate as additional subpackets are used. This results in a lower subpacket error rate compared 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 systematic bits and punctured parity bits are transmitted in the first subpacket. If the signal-to-noise ratio (SNR) environment on the receiving side is good (i.e., high SNR), self-decoding is possible. In some embodiments, subpackets with corresponding SPIDs to be transmitted are in increasing order of SPID, but can be swapped / switched except for the first SPID.

[0103] AP cooperation has been discussed as a potential technology to be adopted in IEEE 802.11be to improve WLAN systems, and there is a high-level classification according to various AP cooperation methods. For example, there is a first type of cooperation method in which data for a user is transmitted from a single AP (sometimes referred to as "coordinated"), and there is a second type of cooperation method in which data for a user is transmitted from multiple APs (sometimes referred to as "joint").

[0104] In a coordinated scheme, multiple APs either 1) transmit on the same frequency resource in a coordinated manner, forming spatial nulls to allow simultaneous transmission from multiple APs, or 2) transmit on orthogonal frequency resources by coordinating and partitioning the spectrum to use the spectrum more efficiently. In a cooperative scheme, multiple APs transmit jointly for a given user.

[0105] As mentioned above, conventional WLANs allow stations to occupy a channel or link for relatively long periods of time (e.g., by granting a transmission opportunity (TXOP) to the STA) to avoid having to contend with other STAs for channel access. However, this feature of conventional WLANs makes it difficult for low-latency applications or STAs to obtain channel access opportunities, which makes it difficult to meet strict latency requirements.

[0106] Described herein are embodiments that allow an AP or a (non-AP) STA to transmit low-latency data in the middle of another AP / STA's TXOP by preempting that TXOP. Three scenarios are described below. These scenarios may occur in the context of a wireless network including an AP and one or more STAs (e.g., STA1-STAn). The first scenario is a scenario in which the AP has low-latency data to transmit in the TXOP of a TXOP holder STA (STA1). The second scenario is a scenario in which a first STA (STAn) has low-latency data to transmit in the TXOP of another STA (STA1). The third scenario is a scenario in which a STA (STAn) has low-latency data to transmit in the AP's TXOP. Scenario 1: The AP has low-latency data to transmit in STA1's uplink TXOP.

[0107] FIG. 8 illustrates a scenario in which the AP has low latency data to transmit to STAn-1 during STA1's uplink TXOP, according to some embodiments.

[0108] As shown in the figure, after a DIFS interval, STA1 may transmit an RTS frame 805. After a SIFS interval, the AP may transmit a CTS frame 810.

[0109] After the SIFS interval, STA1 may transmit a data frame 815 (including non-LL data) to the AP during STA1's (uplink) TXOP. While the AP is receiving the data frame 810 from STA1, the AP may determine that it has low-latency data 820 that needs to be sent urgently to STAn-1. Low-latency data is data that will be sent with low latency (e.g., urgent data). What is considered low-latency data may depend on the specific implementation.

[0110] After a SIFS interval, the AP may send a Block ACK frame 825 to STA1 acknowledging the data frame 815. After a SIFS interval, the AP may send a low-latency data frame 830 containing low-latency data to STAn-1. The low-latency data frame may be a data frame carrying low-latency data (e.g., urgent data).

[0111] After a SIFS interval, STAn-1 may send a Block ACK frame 835 to the AP acknowledging the low latency data frame 830. Thus, the AP may be considered to be preempting or intercepting STA1's TXOP in order to transmit the low latency data frame 830 to STAn-1.

[0112] However, during STA1's TXOP, STA1 cannot recognize that the AP has low-latency data to transmit to STAn-1. As a result, there is no way for the AP to transmit low-latency data to STAn-1 during STA1's TXOP (because the AP is not allowed to ignore the Tx / Rx (transmit / receive) process between the AP and STA1 during STA1's TXOP). That is, conventional WLAN mechanisms do not allow the AP to transmit low-latency data frame 830 to STAn-1 during STA1's TXOP.

[0113] To allow the AP to transmit low-latency data to STAn-1 during STA1's TXOP, the following functionality may be desirable: (1) STA1 should be able to directly / indirectly recognize that the AP has low-latency data to transmit during STA1's TXOP; and (2) if STA1's TXOP is preempted (taken by the AP and / or STAn-1) by the AP and / or another STA to transmit low-latency data, STA1's TXOP should be extended by an appropriate length (to reward STA1 for allowing the AP and / or another STA to preempt STA1's TXOP) to ensure fairness. Scenario 1 Functionality 1

[0114] FIG. 9 illustrates how an AP may preempt STA1's TXOP to transmit low-latency data, according to some embodiments.

[0115] As shown in the figure, after a DIFS interval, STA1 may transmit an RTS frame 905. After a SIFS interval, the AP may transmit a CTS frame 910.

[0116] After the SIFS interval, STA1 may transmit a data frame 915 (including non-LL data) to the AP during STA1's TXOP. While the AP is receiving the data frame 910 from STA1, the AP may determine that it has low-latency data 920 that needs to be sent urgently to STAn-1 (although this particular example is one in which the AP has low-latency data to send to STAn-1, the same techniques described herein may be used to allow the AP to send low-latency data to any other STA associated with the AP, including the TXOP holder STA (i.e., STA1).

[0117] After a SIFS interval, the AP may send a Block ACK frame 925 to STA1 acknowledging the Data frame 915. The Block ACK frame 925 may include an indication that the AP has low-latency data to transmit and that STA1 should withhold its transmission. The indication may serve as a preemption request indicator to indicate that preemption of the TXOP is required to transmit the low-latency data.

[0118] In one embodiment, the indication is included in a field in the preamble of Block Ack frame 925. For example, the indication may be included in the U-SIG field or UHR-SIG field (UHR stands for ultra-high reliability) of the preamble. In one embodiment, the indication is included in a field in the Medium Access Control (MAC) Protocol Data Unit (PDU) of Block Ack frame 925.

[0119] In one embodiment, the indication is a single bit. In one embodiment, the indication comprises multiple bits. In one embodiment, one of the bits comprising the indication indicates whether the indication applies to data contained in the current frame or to data contained in a buffered (future) frame.

[0120] Upon receiving Block ACK frame 925 from the AP, STA1 may recognize that the AP has low-latency data to transmit based on the indication included in Block ACK frame 925 (e.g., this may be included in the preamble of Block ACK frame 925 or the MPDU of Block ACK frame 925). As a result, STA1 may defer its transmission. For example, STA1 may defer its transmission by determining not to transmit data using a SIFS interval following transmission of Block ACK frame 925, but may use a longer IFS interval, such as a PIFS interval or a DIFS interval.

[0121] After a SIFS interval following the AP's transmission of Block ACK frame 925, the AP may transmit a low-latency data frame 930 (containing low-latency data) to STAn-1. In this way, the AP can preempt STA1's TXOP to transmit the low-latency data to STAn-1.

[0122] It is noted that if both the AP and STA1 use the same IFS interval (e.g., a SIFS interval) to transmit data, a collision between the AP and STA1 may occur. Thus, in one embodiment, STA1, the TXOP holder in this example, uses a longer interframe spacing interval than that used by the AP (e.g., the AP uses a SIFS interval, while STA1 uses a PIFS or DIFS interval), thereby allowing the AP to preempt STA1's TXOP following transmission of Block ACK frame 925. That is, if STA1 recognizes (e.g., based on an indication included in the Block ACK frame) that the AP has low-latency data to transmit, STA1 prioritizes the AP's transmission by using a longer IFS interval than that used by the AP (which may be predetermined by a protocol). In one embodiment, the AP uses a SIFS interval following transmission of Block ACK frame 925, and STA1 uses a PIFS or DIFS interval (which are longer than SIFS) following transmission of Block ACK frame 925.

[0123] The use of different IFS intervals provides benefits in cases where the AP's transmission of low-latency data frame 930 fails for some reason. For example, if the AP's transmission of low-latency data frame 930 fails, STA1 can still transmit data frame 935 (e.g., after a PIFS interval or a DIFS interval), thereby maintaining STA1's TXOP. If the channel is occupied through the use of the RTS / CTS protocol, other STAs are not permitted to access the channel during the PIFS interval. That is, the use of different IFS intervals gives priority to the AP (so that the AP can transmit low-latency data), while still allowing the TXOP to be maintained for the TXOP holder if the AP's transmission fails.

[0124] FIG. 10 is a diagram illustrating the interpretation of bits B20-B23 of the U-SIG field according to some embodiments.

[0125] The example shown in the figure assumes that bits B20-B23 of the U-SIG field 1402 (e.g., these are ignore bits in the U-SIG field of the EHT PPDU) are used to indicate that the AP has low latency data to transmit.

[0126] Bits B21 to B23 can be used to indicate the low delay level of the low delay data, which indicates the urgency of the data or the level of transmission priority of the data.

[0127] Bit B20 may be used to indicate whether the low latency level is applied to the current frame or to a future frame. As shown in the figure, bit B20 set to '0' may indicate that the low latency level is applied to data contained in the current data frame, and bit B20 set to '1' may indicate that the low latency level is applied to data contained in a future frame.

[0128] Also, as shown in the figure, bits B21-B23 set to "000" may indicate low latency level 0 (non-LL (non-urgent) data), bits B21-B23 set to "001" may indicate low latency level 1, and bits B21-B23 set to "110" may indicate low latency level 6, which in this example is the highest low latency level (most urgent). There may be other bit values ​​indicating other low latency levels, as indicated by the ellipsis in the figure. Bits B21-B23 set to "111" may indicate the presence of even lower latency data.

[0129] Therefore, in this example, 4 bits (B20 to B23) are used to indicate the presence / absence of low latency data and the low latency level of that low latency data.

[0130] In one embodiment, the same or similar bit encoding / interpretation shown in the figure may be used in the UHR-SIG field instead of the U-SIG field 1402 to indicate the presence of low-latency data and the low-latency level of that low-latency data.

[0131] 11 is a diagram illustrating a Block Ack frame format according to some embodiments. As shown, the Block Ack frame format includes a frame control field 1102 (2 octets), a time length field 1104 (2 octets), a receiver address (RA) field 1106 (6 octets), a transmitter address (TA) field 1108 (6 octets), a BA control field 1110 (2 octets), a BA information field 1112 (variable length), and a frame check sequence (FCS) field 1114 (4 octets).

[0132] 12 is a diagram illustrating a BA control field format according to some embodiments. As shown, the BA control field format includes a reserved field 1202 (1 bit), a multi-TID (traffic identifier) ​​field 1204 (1 bit), a compressed bitmap 1206 (1 bit), a GCR (groupcast with retry) mode field 1208 (2 bits), a reserved field 1210 (7 bits), and a TID_INFO field 1212 (4 bits).

[0133] In one embodiment, the indication that the AP has low latency data to send is contained in the reserved subfield of the BA control field, which is a field in a Block ACK frame (which is a MAC Control frame). Scenario 1 Function 2

[0134] FIG. 13 is a diagram illustrating STA1's TXOP being extended to compensate for its TXOP being preempted, according to some embodiments.

[0135] FIG. 13 is the same as FIG. 9 except that it shows that STA1's TXOP may be extended, and the length of the extension is equal to the preemption length of STA1's TXOP. In the example shown in the figure, STA1 obtained its TXOP through fair competition with other STAs. However, to support the AP's low-latency data transmission, STA1 allowed the AP to preempt STA1's TXOP. Because STA1 allowed the AP to preempt STA1's TXOP, STA1 should be rewarded / compensated with an extension of its TXOP corresponding to the length of time that STA1's TXOP was preempted by the AP and / or other STAs. To this end, in one embodiment, STA1 determines a TXOP compensation length corresponding to the length of time that STA1's TXOP was preempted. In the context of TXOP compensation length, "length" refers to a length of time (i.e., duration).

[0136] In the example shown in the figure, the intended receiver of the low-latency data frame 930 is STAn-1. However, other STAs, such as STA1, STA2, and STAn, may overhear the low-latency data frame 930. Also, other STAs may overhear the Block ACK frame 940 transmitted by STAn-1. STA1 may calculate the length of time to transmit the low-latency data frame 930 from the AP to STAn-1 based on the preamble of the low-latency data frame 930. STA1 may determine the TXOP compensation length based on summing the "stolen TXOP time length time" and the "remaining TXOP time length time" (the "remaining TXOP time length" may be the time remaining in the TXOP before the TXOP is preempted). In the example shown in the figure, there is no "remaining TXOP duration time" (because the end time of BA frame 940 coincides with the end time of STA1's TXOP), and therefore STA1 can only consider the "stolen TXOP duration time" and can be compensated with an extension corresponding to the "stolen TXOP duration time."

[0137] In one embodiment, STA1 determines the length of the low latency data frame 930 based on the L-SIG field in the physical layer (PHY) preamble. The L-SIG field is expected to be included in the preamble of the UHR PPDU to support backward compatibility. The L-SIG field may include a rate field, a length field, and a signal tail field. The length field of the L-SIG field may include a TXTIME variable. STA1 may estimate TXTIME based on decoding the length field (e.g., bits B5-B16) of the L-SIG field.

[0138] In one embodiment, STA1 determines the length of the low-latency data frame 930 based on the U-SIG field in the PHY preamble. The U-SIG field is expected to be included in the preamble of Wi-Fi® 7 (IEEE 802.11be) and later and future Wi-Fi® standards (e.g., UHR) for forward compatibility. Therefore, the U-SIG field is expected to be included not only in UHR PPDUs but also in future Wi-Fi® PPDUs. The U-SIG field may include a PHY version identifier field, an UL / DL field, a TXOP field, and others. STA1 may estimate the channel occupancy time by decoding the TXOP field (e.g., bits B13-B19) of the U-SIG field.

[0139] Thus, STA1 may determine the length of the low-latency data frame 930 based on decoding the L-SIG field or U-SIG field of the preamble of the low-latency data frame 930. STA1 may store this value in its buffer. It should be understood that there may be other ways for STA1 to determine / estimate the length of the low-latency data frame 930.

[0140] If the AP successfully transmits a low-latency data frame 930 to STAn-1, and STAn-1 transmits a Block ACK frame 940 acknowledging the low-latency data frame 930, STA1 may intercept the Block ACK frame 940 due to being part of the same BSS as STAn-1. STA1 may determine the length of the Block ACK frame 140 based on decoding the L-SIG or U-SIG field of the preamble of the Block ACK frame 140. STA1 may then determine the total TXOP compensation length based on summing the length of the low-latency data frame 930 and the length of the Block ACK frame 940 (as well as the length of any IFS intervals). For example, STA1 may determine the total TXOP compensation length using the following formula: Compensation Time=T_SIFS+T_LL data+T_SIFS+T_BlockAck

[0141] In the above equation, "Compensation Time" is the TXOP compensation length, "T_SIFS" is the length of the SIFS interval, "T_LL data" is the length of the low latency data frame 930, and "T_BlockAck" is the length of the Block ACK frame 940. Length may refer to a length of time.

[0142] STA1 may extend its TXOP by the TXOP compensation length. During the extended TXOP, STA1 can transmit other data to compensate for the preempted TXOP to ensure fairness.

[0143] STA1 may reacquire its TXOP when it determines that there is no more low-latency data being transmitted. In one embodiment, STA1 determines whether there is more low-latency data to be transmitted using the following technique: If STA1 overhears a low-latency data frame 930 during its own TXOP, STA1 may determine whether there is more low-latency data to be transmitted based on the bits included in the signal field of the preamble of the low-latency data frame 930. If no other TX / RX occurs for the duration of the PIFS interval, STA1 may determine that there is no more low-latency data to be transmitted. In this case, STA1 may reacquire its TXOP and extend its TXOP by the TXOP compensation length. In one embodiment, STA1 may extend its TXOP using a CTS to self frame, as described in more detail herein below.

[0144] FIG. 14 is a diagram illustrating STA1 extending its TXOP with a CTS to self frame, according to some embodiments.

[0145] In the example shown in the figure, the AP and STAs transmit frames 920-940 as described with reference to FIG. 9. In one embodiment, STA1 extends its TXOP using a CTS to self frame. For example, as shown in the figure, after STAn-1 transmits Block-ACK frame 940 to the AP, STA1 may transmit a CTS to self frame 1405 to extend its own TXOP and compensate for its preempted TXOP (e.g., preempted by the AP). When STA1 transmits the CTS to self frame 1405, other STAs that overhear the CTS to self frame 1405 may set their network allocation vector (NAV) values ​​to protect STA1's transmission / reception. Therefore, the use of the CTS to self frame 1405 helps ensure the extension of STA1's TXOP. After a SIFS interval following the transmission of the CTS to self frame 1405, STA1 may transmit a data frame 1410 during its extended TXOP.

[0146] Such techniques for extending and protecting a TXOP can be applied to other scenarios described below: Scenario 2: STAn has low-latency data to send during STA1's uplink TXOP.

[0147] FIG. 15 illustrates a scenario in which STAn has low latency data to transmit to the AP during STA1's uplink TXOP, according to some embodiments.

[0148] As shown in the figure, after a DIFS interval, STA1 may transmit an RTS frame 1505. After a SIFS interval, the AP may transmit a CTS frame 1510.

[0149] After the SIFS interval, STA1 may transmit data frame 1515 (including non-LL data) to the AP during STA1's (uplink) TXOP. While STA1 is transmitting data frame 1515 to the AP, STAn-1 and STAn may determine that they have low-latency data (low-latency data 1520 and low-latency data 1525) to transmit to the AP, respectively.

[0150] After a SIFS interval following transmission of the data frame 1515, the AP may transmit a Block ACK frame 1530 to STA1 acknowledging the data frame 1515. After the SIFS interval, the AP may transmit a trigger frame (TF-R) 1535 to schedule a random access uplink transmission. After the SIFS interval, the STAn may transmit a low-latency data frame 1540 containing low-latency data to the AP during the random access uplink transmission. After the SIFS interval, the AP may transmit a multi-block ACK frame 1545 to the STAn acknowledging the low-latency data frame 1540.

[0151] In the example shown in the figure, the AP preempts STA1's TXOP to send a TF-R frame 1535 and receives a low-latency data frame 1540 from STAn. This is not a typical situation in a conventional WLAN. In a conventional WLAN, the AP cannot recognize that STAn has low-latency data to send to the AP. Furthermore, there is no way for a conventional WLAN to determine which STA is selected to send low-latency data to the AP (e.g., if both STAn-1 and STAn have low-latency data to send to the AP, there is no way for a conventional WLAN to determine which of these STAs is authorized to send low-latency data to the AP).

[0152] To allow other STAs to transmit low-latency data during STA1's TXOP, the following functions may be desirable: (1) the AP should be able to directly / indirectly recognize that other STAs may have low-latency data to transmit during STA1's TXOP, and the STAs should be selected through fair competition to transmit the low-latency data; and (2) if STA1's TXOP is preempted (e.g., seized by STAn) by another STA to transmit low-latency data, STA1's TXOP should be extended by an appropriate length (to reward STA1 for allowing another STA to preempt STA1's TXOP) to ensure fairness. Scenario 2 Function 1

[0153] FIG. 16 illustrates how STAn may preempt STA1's TXOP to transmit low-latency data, according to some embodiments.

[0154] As shown in the figure, after a DIFS interval, STA1 may transmit an RTS frame 1605. After a SIFS interval, the AP may transmit a CTS frame 1610.

[0155] After the SIFS interval, STA1 may transmit data frame 1615 (including non-LL data) to the AP during STA1's TXOP. Data frame 1615 may include an indication that STA1 has low-latency data to transmit. In one embodiment, the indication not only indicates that STA1 has low-latency data to transmit, but also indicates the low-latency level of the low-latency data (e.g., similar to the indication included in Block ACK frame 925 used in Scenario 1 described above). The low-latency data may be data buffered at STA1 that will be transmitted after data frame 1615. In this example, because the AP, STA2, STAn-1, and STAn have the same BSS color as STA1, they may be able to overhear data frame 1615 transmitted by STA1 to the AP.

[0156] While STA1 is transmitting data frame 1615 to the AP, STAn-1 and STAn may determine that they have low-latency data (low-latency data 1620 and low-latency data 1625) to transmit to the AP, respectively. STAn-1 and STAn may determine the low-latency level of STA1's low-latency data based on decoding the intercepted data frame 1615 transmitted by STA1 (e.g., based on instructions contained therein).

[0157] After a SIFS interval following receipt of data frame 1615, the AP may transmit a Block ACK frame 1630 to STA1 acknowledging data frame 1615.

[0158] When the AP receives a data frame 1615 from STA1, it may determine (based on the indication included in the data frame 1615) that STA1 has low-latency data to transmit. However, to determine whether any other STAs have more urgent low-latency data to transmit, the AP may transmit a TF-R frame 1635 scheduling a random access uplink transmission (e.g., the TF-R frame 1635 may allocate a random access resource unit (RU)). Thus, when STA1 transmits a data frame 1615 to the AP, STA1 may indicate in the data frame 1615 whether STA1 has low-latency data to be transmitted. When the AP receives the data frame 1615 from STA1, the AP may determine whether polling is required to support the request for low-latency data. If the AP determines that polling is required, the AP may transmit a TF-R frame 1635 to request low-latency data from the STA.

[0159] The STAs receiving the TF-R frame 1635 may determine whether they are permitted to transmit their low-latency data to the AP during the random access uplink transmission based on the low-latency levels of their own low-latency data and STA1's low-latency data (e.g., these may be determined based on overhearing STA1's data frame 1615). In one embodiment, a STA determines that if its low-latency data is less urgent than STA1's low-latency data, it is not permitted to participate in the random access uplink transmission. The determination of which STA is given the opportunity to transmit low-latency data during the random access uplink transmission may be made based on the low-latency levels of the low-latency data of the multiple STAs and fair competition among the STAs. In the example shown in the figure, STAn is assumed to have the most urgent low-latency data, so STAn transmits a low-latency data frame 1640 to the AP during the random access uplink transmission (after the SIFS interval following the transmission of the TF-R frame 1635).

[0160] After a SIFS interval, the AP may transmit a multi-block ACK frame 1645 acknowledging the low latency data frame 1640 .

[0161] STAs receiving the TF-R frame 1635 may determine whether they are allowed to transmit during random access uplink transmission according to a predetermined function / algorithm. For example, the STA may set / define an OFDMA contention window (OCW) value based on the low-latency level of the STA's low-latency data, determine an OFDMA backoff (OBO) value by selecting any integer between 0 and the OCW value, increment the OBO value by a certain amount, and determine whether the OBO value is greater than or equal to a predefined threshold. The STA may determine that it is allowed to transmit during random access uplink transmission if the resulting OBO value is greater than or equal to the predefined threshold, and may determine that it is not allowed to transmit during random access uplink transmission if the resulting OBO value is less than the predefined threshold. If the STA is allowed to transmit during the random access uplink transmission, the STA may transmit its low latency data to the AP using a random access resource unit during the random access uplink transmission (e.g., the random access resource unit may be specified in the TF-R frame 1635).

[0162] As an example, in the context of the situation shown in FIG. 16, the TF-R frame 1635 transmitted by the AP may indicate that there is one available random access resource unit, and the STAs may be aware of this. It is also assumed that STA1 has low-latency data with low-latency level 3, STAn-1 has low-latency data with low-latency level 3, and STAn has low-latency data (e.g., most urgent data) with low-latency level 6, where the low-latency level is used as the OCW value. Each STA may randomly select an integer between 0 and its OCW value to determine its OBO value. In this example, it is assumed that STA1's OBO value is 3, STAn-1's OBO value is 2, and STAn's OBO value is 6. Each STA may then increment its OBO value by the number of random access resource units available for random access uplink transmission. In this example, there is one available random access resource unit for random access uplink transmission. Therefore, STA1's OBO value becomes 4, STAn-1's OBO value becomes 3, and STAn's OBO value becomes 7 (i.e., each OBO value is incremented by 1). Each STA may then determine whether its OBO value is greater than or equal to a predefined threshold. In this example, the predefined threshold is 7. Therefore, STAn may determine that it is allowed to transmit during the random access uplink transmission (its OBO value is greater than or equal to the threshold). Therefore, STAn may transmit its low-latency data to the AP using the random access resource unit during the random access uplink transmission.

[0163] In one embodiment, the OCW value, the OBO value, and the predefined threshold are defined as follows (which may be referred to as Algorithm 1):

[0164] 1) OCW_min=the low latency level of its buffered low latency data that the STA wants to send to the AP (e.g., OCW_min for STA1, STA2, and STA3 may be set to 3, 3, and 6, respectively);

[0165] 2) OCW_max = highest low latency level (e.g., low latency level 6 according to the example shown in Figure 10);

[0166] 3) OBO=random_integer(0,OCW_min) (i.e., a random integer between 0 and OCW_min) (e.g., OBO for STA1, STA2, and STA3 can be set to 1, 2, and 5, respectively);

[0167] 4) If the OBO value is greater than the number of random access resource units, the STA selects one of the random access resource units to use for data transmission; if the OBO value is not greater than the number of random access resource units, the STA performs steps 5 and 6 (for example, assuming the number of random access resource units is 2, STA3 can transmit low-latency data using the random access resource unit (because STA3's OBO is greater than 2), but STA1 and STA2 cannot);

[0168] 5) threshold_value is set to a predetermined value (e.g., threshold_value = highest low-latency level (e.g., low-latency level 6) + number of random access resource units (e.g., 2 in the above example) = 8);

[0169] 6) The STA adds / sums the number of random access resource units to the OBO value, and if the sum is greater than or equal to threshold_value, selects one of the random access resource units to use for data transmission (e.g., neither STA1 nor STA2 can transmit low latency data because their respective sum (OBO + number of random access resource units) is not greater than or equal to threshold_value, so the sum for STA1 is 3 (1(OBO) + 2(number of random access resource units) = 3) and the sum for STA2 is 4 (2(OBO) + 2(number of random access resource units) = 4)).

[0170] Although specific methods for determining / defining the OBO value, OCW value, and predefined thresholds are described above, it should be understood that these values ​​may be determined / defined in other ways.

[0171] If there is only one available random access resource unit and there are multiple STAs with OBO values ​​above a predefined threshold, a resource unit collision may occur, and the transmission of low-latency data may fail. Furthermore, even if the number of STAs with OBO values ​​above a predefined threshold is less than the number of available random access resource units, a scenario may still exist in which multiple STAs select / use the same random access resource unit. Similarly, in this case, a resource unit collision may occur, and the transmission of low-latency data may fail. In one embodiment, the AP may transmit a multiuser block ACK (MU-BA) frame to notify the STAs whether the transmission of low-latency data was successful or not. In one embodiment, if the transmission of low-latency data fails, the STAs may reset their OCW and OBO values ​​and repeat the process described above to transmit their low-latency data again.

[0172] In one embodiment, the new / reset OCW and OBO values ​​are calculated as follows:

[0173] 1)OCW_new=OCW_old+1;

[0174] 2) If OCW_new is greater than or equal to OCW_max, OCW_new is set to be OCW_max;

[0175] 3) OBO = random integer(0,OCW_new)

[0176] 4) Repeat steps 4, 5, and 6 of Algorithm 1 described above.

[0177] FIG. 17 illustrates pseudocode for determining whether a STA is allowed to transmit during an (OFDMA) random access uplink transmission, according to some embodiments.

[0178] As shown in the figure, OCW min is set to the low latency level of the STA's buffered low latency data, and OCW max is set to the maximum delay level.

[0179] If this is the first transmission attempt, the OCW min and OBO is set to a random integer between 0 and OCW.

[0180] Otherwise, if this is not the first transmission (it is a retransmission (e.g. because the initial transmission failed)), the OCW is set to the previous OCW incremented by one.

[0181] OCW is OCW max If OCW is greater than or equal to OCW max OBO is then set to be a random integer between 0 and OCW.

[0182] OBO then calculates the number of resource units (N RU ) The STA selects a random resource unit to use for low-latency data transmission if the OBO is greater than or equal to a predefined threshold.

[0183] FIG. 18 illustrates STA1's TXOP being extended to compensate for its TXOP being preempted, according to some embodiments.

[0184] FIG. 18 illustrates the same interaction between the AP and STAs as FIG. 16 (starting with data frame 1615), except that it shows that STA1's TXOP may be extended and that the extension length is equal to the preemption length of STA1's TXOP. STA1's TXOP was preempted after STA1 received Block ACK frame 1630. STA1 may determine the TXOP compensation length based on the length of TF-R frame 1635, the length of low-latency data frame 1640, and the length of multi-block ACK frame 1645 (as well as any IFS interval). Following the AP's transmission of multi-block ACK frame 1645, STA1 may extend its TXOP by the TXOP compensation length (e.g., using a CTS to self frame as described above). Scenario 3: The STA has low-latency data to transmit during the AP's downlink TXOP.

[0185] FIG. 19 illustrates a scenario in which a STA has low latency data to transmit to an AP during the AP's downlink TXOP, according to some embodiments.

[0186] As shown in the figure, after a DIFS interval, the AP may transmit an RTS frame 1905. After a SIFS interval, STA1 may transmit a CTS frame 1910.

[0187] After the SIFS interval, the AP may transmit data frame 1920 (including non-LL data) to STA1 during the AP's TXOP. While the AP is transmitting data frame 1920 to STA1, STAn-1 and STAn may determine that they have low-latency data (low-latency data 1925 and low-latency data 1930) that needs to be sent to the AP urgently. As previously mentioned, what is considered low-latency data may depend on the specific implementation.

[0188] In conventional WLAN mechanisms, the AP cannot recognize that STAn-1 and STAn have low-latency data to transmit. One way to solve this problem is to have the AP stop its transmission and periodically check the STAs to see if they have low-latency data to transmit. However, it is very inefficient for the AP to stop its transmission and check for low-latency data that may or may not be present.

[0189] To allow a STA to transmit low-latency data to the AP during the AP's TXOP, the following functions may be desirable: (1) the AP should be able to directly / indirectly recognize that a STA may have low-latency data to transmit; and (2) if the AP's TXOP is preempted by a STA to transmit low-latency data (e.g., stolen by a STAn), the AP's TXOP should be extended by an appropriate length (to reward the AP for allowing the STA to preempt the AP's TXOP) to ensure fairness. Scenario 3 Function 1

[0190] FIG. 20 illustrates how a STAn may preempt an AP's TXOP to transmit low-latency data, according to some embodiments.

[0191] As shown in the figure, after a DIFS interval, the AP may transmit an RTS frame 2005. After a SIFS interval, STA1 may transmit a CTS frame 2010.

[0192] After the SIFS interval, the AP may transmit a combined data frame and trigger frame 2015 (data+TF-R) during the AP's TXOP. The combined data frame and trigger frame may include a data frame portion (including non-LL data) intended for STA1 and a trigger frame portion that schedules uplink transmission and random access uplink transmission by STA1. While the AP is transmitting the combined data frame and trigger frame 2015, STAn-1 and STAn may determine that they have low-latency data (low-latency data 2020 and low-latency data 2025, respectively) that needs to be transmitted urgently to the AP. The trigger frame portion of the combined data frame and trigger frame 2015 may be used to check whether any STA has low-latency data to transmit to the AP (in this sense, it provides a preemption request handling function). If any STA has low-latency data to transmit, they may transmit the low-latency data using an OFDMA transmission scheme using the resource units allocated by the trigger frame portion of the combined data frame and trigger frame 2015. Thus, the combined data frame and trigger frame 2015 may be considered an instance of a combined data frame and preemption request response frame.

[0193] After a SIFS interval following transmission of the combined data frame and trigger frame 2015, STA1 may transmit a Block ACK frame 2030 to the AP acknowledging the data frame portion of the combined data frame and trigger frame 2015 using the resource units allocated to STA1 by the combined data frame and trigger frame 2015.

[0194] STAs (e.g., STAn-1 and STAn) having low-latency data to transmit to the AP may determine (e.g., using the OCW / OBO algorithm described above when describing scenario 2) whether they are allowed to transmit the low-latency data during the random access uplink transmission, and STAs that are allowed to transmit the low-latency data may transmit the low-latency data frame (including the low-latency data) to the AP using the combined data frame and random access resource unit allocated by the trigger frame 2015 during the random access uplink transmission.

[0195] In the example shown in the figure, the trigger frame portion of the combined data frame and trigger frame 2015 is assumed to allocate two resource units for uplink transmission, with the first resource unit (RU1) allocated to STA1 and the second resource unit (RU2) allocated to a random access resource unit. Also in this example, it is assumed that STAn determines that it is permitted to transmit low-latency data during its random access uplink transmission (e.g., because it has more urgent data to transmit to the AP compared to STAn-1). Thus, STA1 transmits a Block ACK frame 2030 to the AP using RU1, and STAn transmits a low-latency data frame 2035 to the AP using RU2. The transmission of the Block ACK frame 2030 and the low-latency data frame 2035 may be simultaneous (e.g., using uplink OFDMA transmission techniques).

[0196] After a SIFS interval following the simultaneous transmission of the Block ACK frame 2030 and the Low-Latency Data frame 2035, the AP may transmit a Multi-Block ACK frame 2040 that acknowledges the Block ACK frame 2030 and the Low-Latency Data frame 2035. In one embodiment, the AP transmits a combined data frame and multi-block ACK frame instead of a multi-block ACK frame. The combined data frame and multi-block ACK frame may include a data frame portion intended for the STA and a multi-block ACK frame portion that acknowledges the Block ACK frame 2030 and the Low-Latency Data frame 2035.

[0197] In one embodiment, if STA1 determines that it has low-latency data to transmit (before transmitting Block ACK frame 2030), STA1 may include an indication in Block ACK frame 2030 indicating that STA1 has low-latency data to transmit and that the AP should defer its transmission (e.g., similar to the indication included in Block ACK frame 925 in FIG. 9). In this case, STA1 may transmit a low-latency data frame (including the low-latency data) to the AP after the SIFS interval following transmission of Block ACK frame 2030, and the AP may defer the transmission by using a longer IFS interval (e.g., a PIFS interval or a DIFS interval). Thus, the combined data frame and trigger frame portion of trigger frame 2015 may be interpreted as equivalent to querying multiple STAs as to whether they have low-latency data. A STA (e.g., STA1) with low-latency data to transmit may respond by transmitting a frame indicating that it has low-latency data to transmit (e.g., Block ACK frame 2030 including an indication that STA1 has low-latency data to transmit).

[0198] The approach described above with reference to FIG. 20 offers advantages over other approaches. For example, one approach to allowing STAs to transmit low-latency data during an AP's TXOP would be for the AP to periodically transmit a trigger frame to grant the STA an opportunity to transmit low-latency data to the AP. However, this can result in wasted resources. In the worst case, if no STAs have low-latency data to transmit to the AP, the AP loses the opportunity to transmit data, wastes resources by transmitting a trigger frame to STAs that would not use the random access uplink transmission scheduled by the trigger frame, and the AP terminates the TXOP. Additionally, the overall radio resource idle time becomes longer. From the AP's perspective, periodically transmitting a trigger frame benefits STAs by providing them with an opportunity to transmit low-latency data, but from the perspective of overall system performance, this results in a significant loss because no meaningful action is taken if the STA does not have low-latency data to transmit. In contrast, the approach using combined data and trigger frames described above allows other STAs in the same BSS to transmit non-LL data even if no STAs have low-latency data to transmit to the AP. That is, even if there are no STAs with low latency data to transmit, the STAs may still transmit non-LL data to the AP during a random access uplink transmission (e.g., using a random access resource unit). Also, the TXOP may be obtained by the AP not terminating early. Scenario 3 Function 2

[0199] FIG. 21 illustrates an AP's TXOP being extended to compensate for its preemption, according to some embodiments.

[0200] Figure 21 illustrates the same interaction between the AP and STAs as Figure 20, except that it shows that the AP's TXOP may be extended and that the extension length is equal to the AP's TXOP preemption length. The AP may determine the TXOP compensation length based on the length of the trigger frame portion of the combined data frame and trigger frame 2015, the increased length of transmission time due to the use of uplink OFDMA (e.g., splitting resource units instead of being able to receive the Block ACK frame 2030 using the entire bandwidth), and the length of the multi-block ACK frame 2040. For example, the AP may determine the TXOP compensation length by summing these lengths (as well as any IFS intervals). Following the AP's transmission of the multi-block ACK frame 2040, the AP may extend its TXOP by the TXOP compensation length (e.g., using the CTS to self frame described above).

[0201] 22, a method 2200 performed by an AP to transmit low latency data during a TXOP of a first STA is described, according to an example embodiment. The AP may be implemented by a wireless device.

[0202] Additionally, although shown in a particular order, in some embodiments, the operations of method 2200 (and other methods shown in other figures) may be performed in a different order. For example, while the operations of method 2200 are shown in sequential order, some of the operations may be performed in partially or wholly overlapping time periods.

[0203] In operation 2205, the AP wirelessly receives a data frame from the first STA during the TXOP of the first STA.

[0204] In operation 2205, in response to determining that the AP has low-latency data to transmit, the AP wirelessly transmits a block acknowledgement (BA) frame to the first STA acknowledging the data frame, where the BA frame includes an indication that the first STA should withhold its transmission because the AP has low-latency data to transmit. The BA frame may be a standard BA frame, an extended BA frame, or a multi-BA frame. In one embodiment, the indication that the AP has low-latency data to transmit is included in a field of the preamble of the BA frame. In one embodiment, the preamble field is a U-SIG field. In another embodiment, the preamble field is a UHR-SIG field. In one embodiment, the indication that the AP has low-latency data to transmit is included in a field of the MPDU of the BA frame. In one embodiment, the field is included in the BA control field of the BA frame. In one embodiment, the indication that the AP has low-latency data to transmit includes 4 bits. In one embodiment, three of the four bits are used to indicate the low-latency level of the low-latency data, and the remaining bit of the four bits is used to indicate whether the low-latency level is for low-latency data contained in the current frame or for low-latency data contained in a future frame.

[0205] In operation 2215, following transmission of the BA frame, the AP wirelessly transmits a low-latency data frame to the second STA. In one embodiment, the low-latency data frame is transmitted after a first inter-frame spacing interval following transmission of the BA frame, where the first inter-frame spacing interval is shorter than a second inter-frame spacing interval to be used by the first STA following transmission of the BA frame. In one embodiment, the BA frame includes an indication that the AP has low-latency data to transmit, causing the first STA to use the second inter-frame spacing interval when attempting to access the wireless channel. In one embodiment, the first inter-frame spacing interval is a SIFS interval, and the second inter-frame spacing interval is a PIFS interval or a DIFS interval. In one embodiment, the AP wirelessly receives a data frame from the first STA after the second inter-frame spacing interval following transmission of the BA frame due to a failed transmission of the low-latency data frame. In one embodiment, the second STA is the same as the first STA.

[0206] In one embodiment, in operation 2220, the AP wirelessly receives a second BA frame from the second STA acknowledging the low latency data frame.

[0207] 23, a method 2300 performed by a first STA to allow an AP to transmit low latency data is described, according to an example embodiment. The first STA may be implemented by a wireless device.

[0208] In operation 2305, the first STA wirelessly transmits a data frame to the AP during the first STA's TXOP.

[0209] In operation 2310, the first STA wirelessly receives a BA frame from the AP acknowledging the data frame. The BA frame may be a standard BA frame, an extended BA frame, or a multi-BA frame.

[0210] In operation 2315, in response to determining that the BA frame includes an indication that the AP has low latency data to transmit, the first STA uses a second interframe spacing interval instead of the first interframe spacing interval when attempting to access the wireless channel, where the second interframe spacing interval is longer than the first interframe spacing interval.

[0211] In one embodiment, in operation 2320, the first STA determines a TXOP compensation length based on the length of the low latency data frame and the length of the BA frame. In one embodiment, the length of the low latency data frame is determined based on the L-SIG field or the U-SIG field of the preamble of the low latency data frame. In one embodiment, the length of the BA frame is determined based on the L-SIG field or the U-SIG field of the preamble of the BA frame.

[0212] In one embodiment, the first STA extends the first STA's TXOP by the TXOP compensation length in operation 2325. In one embodiment, operation 2325 involves operations 2330-2340.

[0213] At operation 2330, the first STA wirelessly transmits a CTS to self frame. At operation 2335, after wirelessly transmitting the CTS to self frame, the first STA wirelessly transmits a data frame to the AP. At operation 2340, after wirelessly transmitting the data frame, the first STA wirelessly receives an ACK frame from the AP that acknowledges the data frame.

[0214] 24, a method 2400 performed by a first STA to allow other STAs to transmit low-latency data during the first STA's TXOP is described, according to an example embodiment. The first STA may be implemented by a wireless device.

[0215] At operation 2405, the first STA wirelessly transmits a data frame to the AP during the first STA's TXOP, where the data frame includes an indication that the first STA has low latency data to transmit.

[0216] In operation 2410, the first STA wirelessly receives a first BA frame from the AP acknowledging the data frame. The first BA frame may be a standard BA frame, an extended BA frame, or a multi-BA frame.

[0217] At operation 2415, the first STA wirelessly receives a trigger frame from the AP after wirelessly receiving the first BA frame, where the trigger frame schedules a random access uplink wireless transmission, and one of the other STAs wirelessly transmits a low-latency data frame to the AP during the random access uplink wireless transmission.

[0218] In operation 2420, the first STA determines a TXOP compensation length based on the length of the trigger frame, the length of the low-latency data frame, and the length of a second BA frame that acknowledges the low-latency data frame and is wirelessly transmitted by the AP to other STAs. The second BA frame may be a standard BA frame, an extended BA frame, or a multi-BA frame.

[0219] At operation 2425, the first STA extends the TXOP of the first STA by the TXOP compensation length. In one embodiment, operation 2425 may involve operations 2430 to 2440. At operation 2430, the first STA wirelessly transmits a CTS to self frame. At operation 2435, the first STA wirelessly transmits a data frame to the AP after wirelessly transmitting the CTS to self frame. At operation 2440, after wirelessly transmitting the data frame, the first STA wirelessly receives an ACK frame from the AP that acknowledges the data frame.

[0220] 25, a method 2500 performed by a first STA to transmit low latency data during a TXOP of a second STA is described, according to an example embodiment. The first STA may be implemented by a wireless device.

[0221] At operation 2505, the first STA intercepts a wireless transmission of a data frame by the second STA to the AP during the second STA's TXOP, where the data frame includes an indication that the second STA has low-latency data to transmit.

[0222] At operation 2515, the first STA receives a trigger frame wirelessly from the AP, where the trigger frame schedules a random access uplink wireless transmission.

[0223] At operation 2520, in response to receiving the trigger frame, the first STA determines whether to wirelessly transmit the first STA's low latency data to the AP during a random access uplink wireless transmission based on the low latency level of the first STA's low latency data and the low latency level of the second STA's low latency data.

[0224] In operation 2525, in response to determining that the first STA is to wirelessly transmit the first STA's low latency data to the AP during the random access uplink wireless transmission, the first STA attempts to wirelessly transmit a low latency data frame including the first STA's low latency data to the AP using a random access resource unit during the random access uplink wireless transmission.

[0225] 26, a method 2600 performed by a first STA to determine whether to wirelessly transmit low latency data to an AP during a random access uplink wireless transmission is described, according to an example embodiment. The first STA may be implemented by a wireless device.

[0226] This method may be one way to perform operation 2520 (determining whether to wirelessly transmit low latency data of the first STA to the AP during a random access uplink wireless transmission).

[0227] At operation 2605, the first STA determines an OFDMA back-off value (also referred to herein as an OBO value) based on the low-latency level of the first STA's low-latency data. Operation 2605 may involve operations 2610 and 2615. At operation 2610, the first STA sets an OFDMA contention window value based on the low-latency level of the first STA's low-latency data. At operation 2615, the first STA randomly selects an integer value between zero and the OFDMA contention window value as the OFDMA back-off value.

[0228] At operation 2620, the first STA increments the OFDMA backoff value by the number of random access resource units available in the random access uplink radio transmission to generate an incremented OFDMA backoff value.

[0229] The first STA determines whether the incremented OFDMA backoff value is greater than or equal to a threshold value at operation 2625. If the incremented OFDMA backoff value is greater than or equal to the threshold value, the first STA determines that it is to wirelessly transmit low-latency data at operation 2630. Otherwise, if the incremented OFDMA backoff value is not greater than or equal to the threshold value, the first STA determines that it is not to wirelessly transmit low-latency data at operation 2635.

[0230] In one embodiment, in response to determining that a previous attempt to wirelessly transmit a low-latency data frame during a random access uplink wireless transmission failed, the first STA may increment the previous OFDMA contention window value to generate an incremented OFDMA contention window value. The first STA may then randomly select an integer value between zero and the incremented OFDMA contention window value to be the OFDMA backoff value. The first STA may then determine whether to wirelessly transmit low-latency data during a next random access uplink wireless transmission based on the selected value.

[0231] 27, a method 2700 performed by an AP to allow a STA to transmit low latency data during the AP's TXOP is described, according to an example embodiment. The AP may be implemented by a wireless device.

[0232] In operation 2705, the AP wirelessly transmits a combined data frame and trigger frame during the AP's TXOP, where the combined data frame and trigger frame includes a data frame portion intended for the first STA and a trigger frame portion that schedules an uplink wireless transmission and a random access uplink wireless transmission by the first STA, and the uplink wireless transmission and the random access uplink wireless transmission by the first STA are to occur simultaneously.

[0233] At operation 2710, the AP wirelessly receives, during an uplink wireless transmission by the first STA, a BA frame in a first resource unit from the first STA, acknowledging the combined data frame and data frame portion of the trigger frame, and wirelessly receives, during a random access uplink wireless transmission, a low-latency data frame in a second resource unit from the second STA. The BA frame may be a standard BA frame, an extended BA frame, or a multi-BA frame.

[0234] In operation 2715, the AP wirelessly transmits a Multi-Block ACK frame acknowledging the BA frame and the Low Latency Data frame to the first STA and the second STA. In one embodiment, the Multi-Block ACK frame is a combined data and Multi-Block ACK frame that includes a portion of the second data frame intended for the first STA.

[0235] In one embodiment, at operation 2720, the AP determines the TXOP compensation length based on the length of the trigger frame portion of the combined data frame and trigger frame, the increase in transmission time due to the use of OFDMA during uplink wireless transmission by the first STA, and the length of the multi-block ACK frame.

[0236] In one embodiment, at operation 2725, the AP extends the AP's TXOP by the TXOP compensation length. In one embodiment, operation 2725 involves operations 2730 to 2740. At operation 2730, the AP wirelessly transmits a CTS to self frame. At operation 2735, the AP wirelessly transmits a data frame to the STA after wirelessly transmitting the CTS to self frame. At operation 2740, after wirelessly transmitting the data frame, the first STA wirelessly receives an ACK frame from the STA that acknowledges the data frame.

[0237] 28, a method 2800 performed by a first STA to allow a second STA to transmit low-latency data during a TXOP of an AP is described, according to an example embodiment. The first STA may be implemented by a wireless device.

[0238] At operation 2805, the first STA wirelessly receives a combined data frame and trigger frame from the AP during the AP's TXOP, where the combined data frame and trigger frame includes a data frame portion intended for the first STA and a trigger frame portion that schedules an uplink wireless transmission by the first STA and a random access uplink wireless transmission together.

[0239] At operation 2810, in response to receiving the combined data frame and trigger frame from the AP, the first STA wirelessly transmits a BA frame to the AP using a first resource unit, acknowledging the data frame portion of the combined data frame and trigger frame, while the second STA wirelessly transmits a low-latency data frame to the AP using a second resource unit during a random access uplink wireless transmission. The BA frame may be a standard BA frame, an extended BA frame, or a multi-BA frame. In one embodiment, the BA frame may include an indication that the first STA has low-latency data to transmit and therefore the AP should withhold its transmission.

[0240] 29, a method 2900 performed by a first STA to transmit low latency data during a TXOP of an AP is described, according to an example embodiment. The first STA may be implemented by a wireless device.

[0241] At operation 2905, the first STA wirelessly receives a combined data frame and trigger frame from the AP during the AP's TXOP, where the combined data frame and trigger frame includes a data frame portion intended for the second STA and a trigger frame portion that schedules an uplink wireless transmission by the second STA and a random access uplink wireless transmission together, where the uplink wireless transmission by the second STA and the random access uplink wireless transmission are to occur simultaneously.

[0242] At operation 2910, the first STA determines whether to transmit data to the AP during a random access uplink wireless transmission based on a low latency level of the low latency data that the first STA is to transmit to the AP.

[0243] At operation 2915, the first STA wirelessly transmits a low-latency data frame including low-latency data to the AP using the first resource unit during a random access uplink wireless transmission, wherein the second STA wirelessly transmits a BA frame to the AP using the second resource unit during an uplink wireless transmission by the second STA. The BA frame may be a standard BA frame, an extended BA frame, or a multi-BA frame.

[0244] While many of the solutions and techniques provided herein are described with reference to WLAN systems, it should be understood that these solutions and techniques are also applicable to other network environments, such as cellular telecommunications networks, wired networks, etc. In some embodiments, the solutions and techniques provided herein may be or be embodied in a product having instructions stored on a non-transitory machine-readable medium (such as a microelectronic memory) that programs one or more data processing components (collectively referred to herein as a "processor" or "processing unit") to perform the operations described herein. In other embodiments, some of these operations may be performed by specific hardware components including hardwired logic (e.g., dedicated digital filter blocks and state machines). The operations may alternatively be performed by any combination of programmed data processing components and fixed, hardwired circuitry components.

[0245] 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 that stores instructions that may be executed by a hardware processor installed on the apparatus. An apparatus may also include one or more other hardware or software elements, including a network interface, a display device, etc.

[0246] Some portions of the foregoing detailed description are presented in terms of algorithms and symbolic representations of operations on data bits within a computer memory. These algorithmic descriptions and representations are the means 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. These operations require 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.

[0247] 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. This disclosure may refer to actions and processes of a computer system or other similar electronic computing device that manipulate and convert data represented as physical (electronic) quantities in the computer system's registers and memory into other data that are also represented as physical quantities in the computer system's memory or registers or other such information storage system.

[0248] The present disclosure also relates to an apparatus for performing the operations herein. This apparatus may be specially constructed for the intended purposes, or it may comprise 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 perform 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-transitory machine-readable storage medium. Such a computer program may be stored on a computer-readable storage medium, such as any type of disk, including, but not limited to, a floppy disk, an optical disk, a CD-ROM, and a magneto-optical disk, a read-only memory (ROM), a random access memory (RAM), an EPROM, an EEPROM, a magnetic or optical card, or any type of medium suitable for storing electronic instructions, each coupled to a computer system bus.

[0249] The algorithms and displays presented herein are not inherently related to any particular computer or other apparatus. Various general-purpose systems may be used with programs in accordance with the teachings herein, or it may prove convenient to construct more specialized apparatus to perform the methods. The structure for a variety of these systems will appear as set forth in the description that follows. In addition, the present disclosure is not described with reference to any particular programming language. It will be understood that a variety of programming languages ​​can be used to implement the teachings of the present disclosure as described herein.

[0250] The present disclosure may be provided as a computer program product or software that may include a machine-readable medium having instructions stored thereon that can be used to program a computer system (or other electronic device) 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, the machine-readable (e.g., computer-readable) medium includes a machine (e.g., computer) readable storage medium such as read-only memory ("ROM"), random access memory ("RAM"), magnetic disk storage media, optical storage media, flash memory components, etc.

[0251] In the foregoing specification, embodiments of the present disclosure have been described with reference to specific exemplary embodiments thereof. It will be apparent that various modifications may be made thereto without departing from the broader spirit and scope of the embodiments of the present disclosure as set forth in the following claims. The specification and drawings are therefore to be regarded in an illustrative rather than a restrictive sense. (Other possible items) (Item 1) 1. A method performed by a wireless device functioning as an access point (AP) in a wireless network for transmitting low latency data, comprising: wirelessly receiving a data frame from a first station (STA) during a transmit opportunity (TXOP) of the first STA; in response to determining that the AP has low-latency data to transmit, wirelessly transmitting a block acknowledgement (BA) frame to the first STA acknowledging the data frame, wherein the BA frame includes an indication that the first STA should withhold its transmission because the AP has low-latency data to transmit; and wirelessly transmitting a low latency data frame to a second STA following the transmission of the BA frame. A method for providing the above. (Item 2) Item 1. The method of claim 1, wherein the low latency data frame is transmitted after a first interframe spacing interval following the transmission of the BA frame, wherein the first interframe spacing interval is shorter than a second interframe spacing interval to be used by the first STA following the transmission of the BA frame. (Item 3) Item 3. The method of item 2, wherein the indication that the AP has low latency data to transmit is included in the BA frame, causing the first STA to use a second inter-frame spacing interval when attempting to access a wireless channel. (Item 4) Item 4. The method of item 3, wherein the first interframe spacing interval is a short interframe spacing (SIFS) interval, and the second interframe spacing interval is a point coordination function interframe spacing (PIFS) interval or a dispersion coordination function interframe spacing (DIFS) interval. (Item 5) receiving a data frame wirelessly from the first STA after the second interframe space interval following the transmission of the BA frame due to a failure in transmission of the low latency data frame; Item 3. The method of item 2, further comprising: (Item 6) Item 1. The method of item 1, wherein the indication that the AP has low latency data to transmit is included in a field in the preamble of the BA frame. (Item 7) 7. The method of claim 6, wherein the field of the preamble is a Universal Signaling (U-SIG) field. (Item 8) 7. The method of claim 6, wherein the field of the preamble is an Ultra High Reliability Signaling (UHR-SIG) field. (Item 9) Item 1. The method of item 1, wherein the indication that the AP has low latency data to transmit is included in a field of a Medium Access Control (MAC) Protocol Data Unit (PDU) of the BA frame. (Item 10) 10. The method of claim 9, wherein the field is included in a BA control field of the BA frame. (Item 11) Item 10. The method of item 1, wherein the indication that the AP has low latency data to transmit includes 4 bits. (Item 12) Item 12. The method according to item 11, wherein three of the four bits are used to indicate a low-delay level of low-delay data, and the remaining one of the four bits is used to indicate whether the low-delay level is for low-delay data included in a current frame or for low-delay data included in a future frame. (Item 13) wirelessly receiving a second BA frame from the second STA acknowledging the low latency data frame; Item 1, further comprising: (Item 14) Item 2. The method of item 1, wherein the second STA is the same as the first STA. (Item 15) 1. A method performed by a wireless device functioning as a first station (STA) in a wireless network to allow an access point (AP) to transmit low latency data, the method comprising: wirelessly transmitting a data frame to the AP during a transmit opportunity (TXOP) of the first STA; wirelessly receiving a block acknowledgement (BA) frame from the AP acknowledging the data frame; and responsive to determining that the BA frame includes an indication that the AP has low latency data to transmit, using a second interframe space interval instead of a first interframe space interval when attempting to access a wireless channel, wherein the second interframe space interval is longer than the first interframe space interval; A method for providing the above. (Item 16) determining a TXOP compensation length based on the length of the low latency data frame and the length of the BA frame; and extending the TXOP of the first STA by the TXOP compensation length; Item 16. The method of item 15, further comprising: (Item 17) The step of extending the TXOP of the first STA by the TXOP compensation length includes: transmitting a Clear to Send (CTS) to self frame over the air; wirelessly transmitting a data frame to the AP after wirelessly transmitting the CTS to self frame; and and after transmitting the data frame wirelessly, receiving an acknowledgement (ACK) frame from the AP for acknowledging the data frame. Item 17. The method according to Item 16, comprising: (Item 18) Item 17. The method of item 16, wherein the length of the low-latency data frame is determined based on a legacy signal (L-SIG) field or a universal signal (U-SIG) field of a preamble of the low-latency data frame, and the length of the BA frame is determined based on an L-SIG field or a U-SIG field of a preamble of the BA frame. (Item 19) 1. A method performed by a wireless device functioning as a first station (STA) in a wireless network to allow other STAs to transmit low latency data, the method comprising: wirelessly transmitting a data frame to an access point (AP) during a transmit opportunity (TXOP) of the first STA, wherein the data frame includes an indication that the first STA has low latency data for transmission; wirelessly receiving a first block acknowledgement (BA) frame from the AP acknowledging the data frame; receiving a trigger frame wirelessly from the AP after wirelessly receiving the first BA frame, where the trigger frame schedules a random access uplink wireless transmission, and one of the other STAs wirelessly transmits a low-latency data frame to the AP during the random access uplink wireless transmission; determining a TXOP compensation length based on a length of the trigger frame, a length of the low-latency data frame, and a length of a second BA frame wirelessly transmitted by the AP to the other STAs acknowledging the low-latency data frame; and extending the TXOP of the first STA by the TXOP compensation length; A method for providing the above. (Item 20) 1. A method performed by a wireless device functioning as a first station (STA) in a wireless network for transmitting low latency data, the method comprising: intercepting, during a transmit opportunity (TXOP) of a second STA, a wireless transmission of a data frame by the second STA to an access point (AP), wherein the data frame includes an indication that the second STA has low latency data for transmission; wirelessly receiving a trigger frame from the AP, where the trigger frame schedules a random access uplink wireless transmission; determining, in response to receiving the trigger frame, whether to wirelessly transmit the low-latency data of the first STA to the AP during the random access uplink wireless transmission based on a low-latency level of the low-latency data of the first STA and a low-latency level of the low-latency data of the second STA; and and in response to the first STA determining that it is to wirelessly transmit the low-latency data of the first STA to the AP during the random access uplink wireless transmission, attempting to wirelessly transmit a low-latency data frame including the low-latency data of the first STA to the AP using a random access resource unit during the random access uplink wireless transmission. A method for providing the above. (Item 21) The step of determining whether to wirelessly transmit the low latency data of the first STA to the AP during the random access uplink wireless transmission includes: determining an Orthogonal Frequency Division Multiple Access (OFDMA) backoff value based on the low-latency level of the low-latency data of the first STA; incrementing the OFDMA backoff value by the number of random access resource units available in the random access uplink radio transmission to generate an incremented OFDMA backoff value; and determining whether the incremented OFDMA backoff value is greater than or equal to a threshold value; Item 21. The method according to Item 20, comprising: (Item 22) Determining the OFDMA backoff value based on the low latency level of the low latency data of the first STA comprises: setting an OFDMA contention window value based on the low-latency level of the low-latency data of the first STA; and randomly selecting an integer value between zero and the OFDMA contention window value as the OFDMA backoff value; 22. The method according to item 21, comprising: (Item 23) The step of determining an OFDMA backoff value comprises: incrementing a previous OFDMA contention window value to generate an incremented OFDMA contention window value in response to determining that a previous attempt to wirelessly transmit the low latency data frame during the random access uplink wireless transmission failed; and randomly selecting an integer value between zero and the incremented OFDMA contention window value as the OFDMA backoff value; 22. The method according to item 21, comprising: (Item 24) 1. A method performed by a wireless device functioning as an access point (AP) in a wireless network to allow a STA to transmit low latency data, comprising: wirelessly transmitting a combined data frame and a trigger frame during a transmission opportunity (TXOP) of the AP, wherein the combined data frame and trigger frame includes a data frame portion intended for a first STA and a trigger frame portion that schedules an uplink wireless transmission and a random access uplink wireless transmission by the first STA, wherein the uplink wireless transmission and the random access uplink wireless transmission by the first STA are to occur simultaneously; receiving, during the uplink wireless transmission by the first STA, a block acknowledgement (BA) frame from the first STA in a first resource unit that acknowledges the data frame portion of the combined data frame and trigger frame, and receiving, during the random access uplink wireless transmission, a low latency data frame from a second STA in a second resource unit; and wirelessly transmitting a multi-block ACK frame that acknowledges the BA frame and the low-latency data frame to the first STA and the second STA; A method for providing the above. (Item 25) determining a TXOP compensation length based on a length of the trigger frame portion of the combined data frame and trigger frame, an increase in transmission time due to use of Orthogonal Frequency Division Multiple Access (OFDMA) during the uplink wireless transmission by the first STA, and a length of the multi-block ACK frame; and extending the TXOP of the AP by the TXOP compensation length; 25. The method of claim 24, further comprising: (Item 26) 25. The method of claim 24, wherein the Multi-Block ACK frame is a combined data and Multi-Block ACK frame that includes a second data frame portion intended for the first STA. (Item 27) 1. A method performed by a first station (STA) in a wireless network for transmitting low latency data, the method comprising: receiving, wirelessly from an access point (AP) during a transmit opportunity (TXOP) of the AP, a combined data frame and a trigger frame, wherein the combined data frame and trigger frame includes a data frame portion intended for the first STA and a trigger frame portion that schedules an uplink wireless transmission and, together, a random access uplink wireless transmission by the first STA; and In response to receiving the combined data frame and trigger frame from the AP, wirelessly transmitting a block acknowledgement (BA) frame to the AP using a first resource unit, the BA frame acknowledging the data frame portion of the combined data frame and trigger frame; wherein a second STA wirelessly transmits a low-latency data frame to the AP using a second resource unit during the random access uplink wireless transmission. A method for providing the above. (Item 28) 28. The method of claim 27, wherein the BA frame includes an indication that the first STA has low latency data to transmit and therefore the AP should withhold its transmission. (Item 29) 1. A method performed by a first station (STA) in a wireless network for transmitting low latency data, the method comprising: receiving, wirelessly from an access point (AP) during a transmission opportunity (TXOP) of the AP, a combined data frame and a trigger frame, wherein the combined data frame and trigger frame includes a data frame portion intended for a second STA and a trigger frame portion that schedules an uplink wireless transmission and a random access uplink wireless transmission by the second STA, wherein the uplink wireless transmission and the random access uplink wireless transmission by the second STA are to occur simultaneously; determining whether to transmit data to the AP during the random access uplink wireless transmission based on a low latency level of low latency data that the first STA is to transmit to the AP; and wirelessly transmitting a low-latency data frame including the low-latency data to the AP using a first resource unit during the random access uplink wireless transmission, wherein the second STA wirelessly transmits a block acknowledgement (BA) frame to the AP using a second resource unit during the uplink wireless transmission by the second STA. A method for providing the above.

Claims

1. 1. A method performed by a wireless device functioning as an access point (AP) in a wireless network for transmitting low latency data, comprising: wirelessly receiving a data frame from a first station (STA) during a transmission opportunity (TXOP) of the first STA; in response to determining that the AP has low-latency data to transmit, wirelessly transmitting a block acknowledgement (BA) frame to the first STA acknowledging the data frame, wherein the BA frame includes an indication that the first STA should suspend its transmission because the AP has low-latency data to transmit; and wirelessly transmitting a low latency data frame to a second STA following the transmission of the BA frame. A method for providing the above.

2. 2. The method of claim 1, wherein the low latency data frame is transmitted after a first inter-frame spacing interval following the transmission of the BA frame, wherein the first inter-frame spacing interval is shorter than a second inter-frame spacing interval to be used by the first STA following the transmission of the BA frame.

3. 3. The method of claim 2, wherein the indication that the AP has low latency data to transmit is included in the BA frame, causing the first STA to use a second inter-frame spacing interval when attempting to access a wireless channel.

4. 4. The method of claim 3, wherein the first interframe space interval is a short interframe space (SIFS) interval and the second interframe space interval is a point coordination function interframe space (PIFS) interval or a distribution coordination function interframe space (DIFS) interval.

5. wirelessly receiving a data frame from the first STA after the second inter-frame spacing interval following the transmission of the BA frame due to a failure in transmission of the low-latency data frame. The method of claim 2 further comprising:

6. The method of claim 1 , wherein the indication that the AP has low latency data to transmit is included in a field of a preamble of the BA frame.

7. 7. The method of claim 6, wherein the field of the preamble is a Universal Signaling (U-SIG) field.

8. 7. The method of claim 6, wherein the field of the preamble is an Ultra High Reliability Signal (UHR-SIG) field.

9. 9. The method of claim 1, wherein the indication that the AP has low latency data to transmit is included in a field of a Medium Access Control (MAC) Protocol Data Unit (PDU) of the BA frame.

10. The method of claim 9 , wherein the field is included in a BA control field of the BA frame.

11. The method of claim 1 , wherein the indication that the AP has low latency data to transmit comprises 4 bits.

12. 12. The method of claim 11, wherein three of the four bits are used to indicate a low-delay level of low-delay data, and the remaining one of the four bits is used to indicate whether the low-delay level is for low-delay data contained in a current frame or for low-delay data contained in a future frame.

13. wirelessly receiving a second BA frame from the second STA acknowledging the low-latency data frame; The method of claim 1 , further comprising:

14. The method of claim 1 , wherein the second STA is the same as the first STA.

15. 1. A method performed by a wireless device functioning as a first station (STA) in a wireless network to allow an access point (AP) to transmit low latency data, the method comprising: wirelessly transmitting a data frame to the AP during a transmission opportunity (TXOP) of the first STA; wirelessly receiving a block acknowledgement (BA) frame from the AP acknowledging the data frame; and responsive to determining that the BA frame includes an indication that the AP has low latency data to transmit, using a second interframe space interval instead of a first interframe space interval when attempting to access a wireless channel, wherein the second interframe space interval is longer than the first interframe space interval; A method for providing the above.

16. 1. A method performed by a wireless device functioning as a first station (STA) in a wireless network for transmitting low latency data, the method comprising: intercepting a wireless transmission of a data frame by a second STA to an access point (AP) during a transmission opportunity (TXOP) of the second STA, wherein the data frame includes an indication that the second STA has low latency data for transmission; wirelessly receiving a trigger frame from the AP, where the trigger frame schedules a random access uplink wireless transmission; determining, in response to receiving the trigger frame, whether to wirelessly transmit the low-latency data of the first STA to the AP during the random access uplink wireless transmission based on a low-latency level of the low-latency data of the first STA and a low-latency level of the low-latency data of the second STA; and and in response to determining that the first STA is to wirelessly transmit the low-latency data of the first STA to the AP during the random access uplink wireless transmission, attempting to wirelessly transmit a low-latency data frame including the low-latency data of the first STA to the AP using a random access resource unit during the random access uplink wireless transmission. A method for providing the above.

17. 1. A method performed by a wireless device functioning as an access point (AP) in a wireless network to allow a STA to transmit low-latency data, the method comprising: wirelessly transmitting a combined data frame and a trigger frame during a transmission opportunity (TXOP) of the AP, wherein the combined data frame and trigger frame include a data frame portion intended for a first STA and a trigger frame portion that schedules an uplink wireless transmission and a random access uplink wireless transmission by the first STA, wherein the uplink wireless transmission and the random access uplink wireless transmission by the first STA are to occur simultaneously; receiving, during the uplink wireless transmission by the first STA, in a first resource unit, a block acknowledgement (BA) frame from the first STA that acknowledges the data frame portion of the combined data frame and trigger frame; and receiving, during the random access uplink wireless transmission, in a second resource unit, a low-latency data frame from a second STA; and wirelessly transmitting a multi-block ACK frame that acknowledges the BA frame and the low-latency data frame to the first STA and the second STA; A method for providing the above.

Images