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, filed on February 27, 2023, entitled "Preemption to Support Low - latency (LL) data"; and U.S. Provisional Application No. 63 / 486,435, filed on February 22, 2023, entitled "Preemption to Support Low - Latency (LL) data", which are hereby incorporated by reference in their entirety. This application also claims priority to U.S. Application No. 18 / 583,475, filed on February 21, 2024, entitled "PREEMPTION TO SUPPORT LOW - LATENCY (LL) DATA", which is hereby incorporated by reference in its entirety.

[0002] This disclosure generally relates to wireless communications, and more specifically, to the use of preemption to support the transmission of low - latency data in a wireless network.

Background Art

[0003] IEEE 802.11 is a set of physical and media access control (MAC) specifications for implementing wireless local area network (WLAN) communication. These specifications provide the basis for wireless network products using 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 bands. These spectral bands are commonly referred to as the 2.4 GHz band and the 5 GHz band. 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 the availability of these channels is restricted in some countries. The 5GHz band is more strictly regulated than the 2.4GHz band, with channel spacing varying across the spectrum, and a minimum spacing of 5MHz depending on the regulations of each country or region.

[0004] WLAN devices are currently deployed in a variety of environments. These environments are characterized by the presence of many access points (APs) and non-AP stations (STAs) in geographically limited areas. Increased interference from neighboring devices leads to performance degradation. In addition, WLAN devices are increasingly required to support a variety of applications, including video, cloud access, and offloading. Video traffic, in particular, is expected to become the primary type of traffic in WLAN deployments. With some of these applications having real-time requirements, 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, standards beyond IEEE 802.11be include the delivery of low-latency traffic for real-time services (e.g., virtual reality (VR), augmented reality (AR), and mixed reality (MR)). In traditional wireless networks, when a station (STA) has a transmit opportunity (TXOP) and transmits data, other devices cannot initiate their own transmissions to ensure the secure transmission of the TXOP holder's data. Such operational scenarios hinder low-latency transmission.

[0006] Traditional WLANs allow stations to occupy a channel or link for relatively long periods (for example, by granting a TXOP to an STA) to avoid the need to compete with other STAs for channel access. However, this feature of traditional WLANs makes it difficult for low-latency applications or stations to obtain channel access opportunities, thereby making it difficult to meet stringent latency requirements. [Brief explanation of the drawing]

[0007] This disclosure will be better understood from the detailed description presented below and from the accompanying drawings of various embodiments of this disclosure. However, these drawings should not be construed as limiting this disclosure to any particular embodiment, but are merely for illustrative and illustrative purposes.

[0008] [Figure 1] The present disclosure illustrates an exemplary wireless local area network (WLAN) having a basic service set (BSS) that includes multiple wireless devices, according to several embodiments of this disclosure.

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

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

[0011]

[0012] [Figure 4] The inter-frame space (IFS) relationships in some embodiments of this disclosure are shown.

[0013] [Figure 5] This disclosure describes several embodiments of a carrier-sense multiple access / collision avoidance (CSMA / CA) based frame transmission procedure.

[0014] [Figure 6] A table comparing various iterations of the Institute of Electrical and Electronics Engineers (IEEE) 802.11 standard according to several embodiments of this disclosure is provided.

[0015] [Figure 7] A table illustrating the fields of the Extreme High Throughput (EHT) frame format according to some embodiments of this disclosure is provided.

[0016] [Figure 8] This figure shows a scenario in which, during the uplink TXOP of STA1, the AP has low-latency data to transmit to STAn-1, according to several embodiments.

[0017] [Figure 9]FIG. showing a method by which an AP can preempt the TXOP of STA1 to transmit low-latency data according to some embodiments.

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

[0019] [Figure 11] FIG. showing the block ACK frame format according to some embodiments.

[0020] [Figure 12] FIG. showing the BA control field format according to some embodiments.

[0021] [Figure 13] FIG. showing that the TXOP of STA1 is extended to compensate for the preemption of the TXOP of STA1 according to some embodiments.

[0022] [Figure 14] FIG. showing that STA1 extends its TXOP using a CTS to self frame according to some embodiments.

[0023] [Figure 15] FIG. showing a scenario where STAn has low-latency data to transmit to the AP during the uplink TXOP of STA1 according to some embodiments.

[0024] [Figure 16] FIG. showing a method by which STAn can preempt the TXOP of STA1 to transmit low-latency data according to some embodiments.

[0025] [Figure 17]This figure shows pseudocode for determining whether an STA is permitted to transmit during an (OFDMA) random access uplink transmission, according to several embodiments.

[0026] [Figure 18] This figure shows that in some embodiments, the TXOP of STA1 is extended to compensate for the preemption of the TXOP of STA1.

[0027] [Figure 19] This figure shows a scenario in which the STA has low-latency data to send to the AP during the AP's downlink TXOP, according to several embodiments.

[0028] [Figure 20] This figure shows how, in several embodiments, a STAn may preempt the AP's TXOP to transmit low-latency data.

[0029] [Figure 21] This figure shows that in some embodiments, the AP's TXOP is extended to compensate for the AP's TXOP being preempted.

[0030] [Figure 22] This flowchart illustrates, in several embodiments, how an AP can perform the transmission of low-latency data during a TXOP of a first STA.

[0031] [Figure 23] This flowchart illustrates how, in several embodiments, a first STA can perform actions to allow an AP to transmit low-latency data.

[0032] [Figure 24] This flowchart illustrates, in several embodiments, how the first STA may perform actions to allow other STAs to transmit low-latency data during the TXOP of the first STA.

[0033] [Figure 25] This flowchart illustrates, in several embodiments, how the first STA can transmit low-latency data during the TXOP of the second STA.

[0034] [Figure 26] This flowchart illustrates a method performed by a first STA to determine whether to wirelessly transmit low-latency data to an AP during random access uplink wireless transmission, according to several embodiments.

[0035] [Figure 27] This flowchart illustrates how, in several embodiments, an AP can perform actions to allow an STA to transmit low-latency data during an AP's TXOP.

[0036] [Figure 28] This flowchart illustrates, in several embodiments, how the first STA can perform actions to allow the second STA to transmit low-latency data during the AP's TXOP.

[0037] [Figure 29] This flowchart illustrates a method performed by a first STA to transmit low-latency data during AP's TXOP, according to several embodiments. [Modes for carrying out the invention]

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

[0039] In some embodiments, an access point (AP) can transmit low-latency data midway through a station's (STA) 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 preemption. In some embodiments, a first STA can transmit low-latency data midway through a second STA's TXOP by preempting the second STA's TXOP. The second STA's TXOP may be extended to compensate for the loss of the TXOP due to this preemption. In some embodiments, an STA can transmit low-latency data midway through an AP's TXOP by preempting the AP's TXOP. The AP's TXOP may be extended to compensate for the loss of the TXOP due to this preemption.

[0040] For illustrative purposes, various embodiments are described herein in the context of wireless networks based on the IEEE 802.11 standard, and using its terminology and concepts. 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 specific embodiments of the present invention are shown and described as illustrative. As those skilled in the art will recognize, all of the embodiments described can be modified in various different ways without departing from the spirit or scope of the invention. Accordingly, the drawings and description should be considered as illustrative and not limiting. Throughout this specification, similar reference numerals indicate similar elements.

[0042] Figure 1 shows a wireless local area network (WLAN) 100 having a basic service set (BSS) 102 including a plurality of wireless devices 104 (which may be 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 compliant with the IEEE (Institute of Electrical and Electronics Engineers) 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 wireless device 104 may initiate the 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, which is 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 not 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. Generally, 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 the sake of clarity, only non-AP STAs may be referred to as STAs. Although shown using four non-AP STAs (e.g., wireless devices 104B1-104B4), the WLAN 100 may include any number of non-AP STAs (e.g., one or more wireless devices 104B).

[0044] Figure 2 shows a schematic block diagram of a wireless device 104 according to one embodiment. The wireless device 104 may be wireless device 104A (i.e., AP of WLAN 100) or one of wireless devices 104B1 to 104B4 in Figure 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, storage device 232, input interface 234, output interface 236, and RF transceiver 240 can 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-temporary computer / machine-readable medium in which software (e.g., computer / machine programming instructions) and data are stored.

[0046] In one embodiment, the MAC processor 212 includes a MAC software processing unit 214 and a MAC hardware processing unit 216. The MAC software processing unit 214 can implement a first set of functions of the MAC layer by executing MAC software that may be contained in software stored in a storage device 232. The MAC hardware processing unit 216 can implement a second set of functions of the MAC layer in dedicated hardware. However, the MAC processor 212 is not limited to these. For example, depending on the implementation, the MAC processor 212 may be configured to execute the first and second sets of functions entirely in software or entirely in hardware.

[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 multiple functions of the PHY layer. These functions can be performed in software, hardware, or a combination thereof, depending on the implementation.

[0048] The functions performed by the transmitting SPU224 may include forward error correction (FEC) coding, stream parsing to one or more spatial streams, diversity coding of spatial streams to multiple spatiotemporal streams, spatial mapping of spatiotemporal streams to the transmission chain, inverse Fourier transform (iFT) calculation, cyclic prefix (CP) insertion to create guard intervals (GI), and one or more of the same. The functions performed by the receiving SPU226 may include the inverse of the functions performed by the transmitting SPU224, such as GI removal, Fourier transform calculation, and the same.

[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 (for example, to another WLAN device 104 of the WLAN 100) and to provide second information received from the WLAN 100 (for example, from another WLAN device 104 of the WLAN 100) to the baseband processor 210.

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

[0051] The input interface 234 receives information from the user, and the output interface 236 outputs information to the user. The input interface 234 may include one or more of the following: a keyboard, keypad, mouse, touchscreen, microphone, and the like. The output interface 236 may include one or more of the following: a display device, touchscreen, 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 in hardware depends on the constraints imposed on the design. These constraints may include one or more of the following: 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 functionality of the components of the WLAN device 104. Furthermore, the WLAN device 104 may include other components such as an application processor, storage interface, clock generator circuit, power supply circuit, and the like, which have been omitted for brevity.

[0054] Figure 3A shows the components of a WLAN device 104 configured to transmit data according to one embodiment, which include a transmitting (Tx) SPU (transmitting SPU: TxSP) 324, an RF transmitter 342, and an antenna 352. In one embodiment, the TxSP 324, RF transmitter 342, and antenna 352 correspond to the transmitting SPU 224, RF transmitter 242, and antenna of the antenna unit 250 in Figure 2, respectively.

[0055] The TxSP324 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 and a subsequent puncturing device. The FEC encoder may also include a low-density parity-check (LDPC) encoder.

[0057] The TxSP324 may further include a scrambler to scramble the input data before encoding is performed by the encoder 300 to reduce the probability of long sequences of 0s or 1s. If the encoder 300 performs BCC encoding, the TxSP324 may further include an encoder parser to demultiplex the scrambled bits across multiple BCC encoders. If LDPC encoding is used within the encoder, the TxSP324 does not need to use an encoder parser.

[0058] The interleaver 302 interleaves the bits of each stream output from the encoder 300, changing the order of the bits inside. The interleaver 302 may apply interleaving only when the encoder 300 is performing BCC encoding; otherwise, it may output the stream from the encoder 300 without changing the order of the bits inside.

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

[0060] When TxSP324 performs MIMO or MU-MIMO transmission, TxSP324 may include multiple interleavers 302 and multiple mappers 304 depending on the number of spatial streams (NSS) of the transmission. TxSP324 may further include a stream parser for dividing the output of encoder 300 into blocks and transmitting these blocks to different interleavers 302 or mappers 304, respectively. TxSP324 may further include a space-time block code (STBC) encoder for expanding constellation points from spatial streams into a number of space-time streams (NSTS), and a spatial mapper for mapping space-time streams to a transmission chain. The spatial mapper may use direct mapping, spatial augmentation, or beamforming.

[0061] IFT306 converts the constellation point blocks output from mapper 304 (or the spatial mapper if MIMO or MU-MIMO is being performed) into time-domain blocks (i.e., symbols) using the inverse discrete Fourier transform (IDFT) or the inverse fast Fourier transform (IFFT). When an STBC encoder and spatial mapper are used, IFT306 may be provided for each transmission chain.

[0062] When TxSP324 performs MIMO or MU-MIMO transmission, TxSP324 may insert cyclic shift diversity (CSD) to prevent unintended beamforming. TxSP324 may insert CSD before or after IFT306. CSD may be specified per transmission chain or per spatiotemporal stream. Alternatively, CSD may be applied as part of a spatial mapper.

[0063] When TxSP324 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 contain a cyclic prefix (CP) corresponding to the repeating portion at the end of the symbol preceding the GI. 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 RF signals and transmits these RF signals via the antenna 352. When the TxSP324 performs MIMO or MU-MIMO transmission, a GI inserter 308 and an RF transmitter 342 may be provided for each transmission chain.

[0066] Figure 3B shows the components of a WLAN device 104 configured to receive data according to one embodiment, which include a receiver (Receiver: Rx) SPU (Receiver SPU: RxSP) 326, an RF receiver 344, and an antenna 354. In one embodiment, the RxSP 326, RF receiver 344, and antenna 354 may correspond to the receiving SPU 226, RF receiver 244, and antenna of the antenna unit 250 in Figure 2, respectively.

[0067] The RxSP326 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 the RF signal via the antenna 354 and converts the RF signal into symbols. The GI remover 318 removes the GI from each of the symbols. If the received transmission is a MIMO or MU-MIMO transmission, the RF receiver 344 and the GI remover 318 may be provided for each receiving chain.

[0069] The FT316 transforms each symbol (i.e., each time-domain block) into a frequency-domain block of a constellation point using either the Discrete Fourier Transform (DFT) or the Fast Fourier Transform (FFT). The FT316 may be provided for each receiving 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 FT316 in the receiving chain into a constellation point of multiple spatiotemporal streams, and an STBC decoder for despreading the constellation points from the spatiotemporal stream into one or more spatial streams.

[0071] The demapper 314 demaps the constellation points output from the FT316 or STBC decoder into a bitstream. If the received transmission was encoded using LDPC coding, the demapper 314 may perform LDPC tone demapping before performing constellation demapping.

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

[0073] If the received transmission is a MIMO or MU-MIMO transmission, the RxSP326 may use multiple demappers 314 and multiple deinterleavers 312 corresponding to the number of spatial streams of the transmission. In this case, the RxSP326 may further include a stream deparser for combining 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 RxSP326 may further include a descrambler for descrambling the decoded data. If the decoder 310 performs BCC decoding, the RxSP326 may further include an encoder deparser for multiplexing data decoded by multiple BCC decoders. If the decoder 310 performs LDPC decoding, the RxSP326 does not need to use an encoder deparser.

[0076] Before transmitting, wireless devices such as wireless device 104 will use Clear Channel Assessment (CCA) to evaluate the availability of the wireless medium. If the medium is occupied, the CCA may determine that it is busy; on the other hand, if the medium is available, the CCA may determine that it is idle.

[0077] PHY entities for IEEE 802.11 are based on Orthogonal Frequency Division Multiplexing (OFDM) or Orthogonal Frequency Division Multiple Access (OFDMA). In either the OFDM or OFDMA physical (PHY) layer, an STA (e.g., wireless device 104) can send and receive PHY Protocol Data Units (PPDUs) that comply with the required PHY specifications. The PHY specifications define the set of Modulation and Coding Schemes (MCS) and the maximum number of spatial streams. Some PHY entities have a maximum number of space-time streams (STS) per user and define downlink (DL) and uplink (UL) multi-user (MU) transmissions that employ a predetermined total number of STS at most. The PHY entity may provide support for continuous channel widths of 10 megahertz (MHz), 20 MHz, 40 MHz, 80 MHz, 160 MHz, 240 MHz, and 320 MHz, and support for non-continuous channel widths of 80+80, 80+160 MHz, and 160+160 MHz. Each channel contains multiple subcarriers, which may also be referred to as tones. The PHY entity may define signaling fields within the PPDU, such as Legacy Signal (L-SIG), Signal A (SIG-A), Signal B (SIG-B), and similar, 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 shows the frame interval (IFS) relationships. In particular, Figure 4 shows 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 shows the slot time, where data frames are used to transmit data to be transferred to the upper layer. As shown, if the DIFS has elapsed while the medium is idle, the WLAN device 104 performs a backoff and then transmits a data frame.

[0079] Management frames may 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 can be used to control access to a medium. Subtypes of control frames include request to send (RTS) frames, clear to send (CTS) frames, and acknowledgment (ACK) frames.

[0081] When the control frame is not a response frame to another frame, the WLAN device 104 sends the control frame after performing a backoff if DIFS has elapsed while the medium is idle. When the control frame is a response frame to another frame, the WLAN device 104 sends the control frame after 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, any data frame, administration frame, or control frame other than a response frame may use the AIFS[AC] of the AC of the transmitted frame.

[0083] If a WLAN device 104 that is ready to forward a frame discovers that the medium is busy, the WLAN device 104 may perform a backoff procedure. The backoff procedure involves 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 according to the length of the Contention Window (CW). In one embodiment, the backoff time may be determined according to 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 duration of that period.

[0084] If the WLAN device 104 detects that there has been no activity on the media for a specified backoff slot duration, the backoff procedure must decrement the backoff time by the slot duration. If the WLAN device 104 determines that the media is busy during the backoff slot, the backoff procedure is paused until the media is again determined to be idle for a duration of the DIFS or EIFS period. When the backoff timer reaches zero, the WLAN device 104 may transmit or retransmit frames.

[0085] The backoff procedure works such that when multiple WLAN devices 104 are waiting to transmit and the backoff procedure is executed, each WLAN device 104 can select a backoff time using a random function, and the WLAN device 104 that selects the shortest backoff time wins the competition and reduces the probability of collision.

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

[0087] Station STA1 can determine whether a channel is busy by carrier sense. Station STA1 can determine channel occupancy / status based on the energy level within the channel or the autocorrelation of signals within the channel, or it can determine channel occupancy by using a network allocation vector (NAV) timer.

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

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

[0090] If station STA1 receives a CTS frame from station STA2, it may send a data frame to station STA2 after the SIFS period has elapsed from the time the CTS frame was fully received. Upon successful receipt of the data frame, station STA2 may send an ACK frame as a response to the data frame after the SIFS period has elapsed.

[0091] If the NAV timer expires, the third station STA3 may use carrier sense to determine whether the channel is busy. If it determines that the channel is not being used by another device during the DIFS period after the NAV timer expires, station STA3 may, in accordance with the backoff process, attempt to access the channel after the conflict window has elapsed.

[0092] When Dual CTS is enabled, a station that has a Transmit Opportunity (TXOP) but has no data to transmit may shorten the TXOP by sending a CF-End frame. An AP that receives a CF-End frame with the AP's Basic Service Set Identifier (BSSID) as the destination address may respond by sending two more CF-End frames: a first CF-End frame using Space Time Block Coding (STBC) and a second CF-End frame without STBC. Upon receiving the CF-End frame, the station resets its NAV timer to 0 at the end of the PPDU containing the CF-End frame. Figure 5 shows that station STA2 sends an ACK frame to acknowledge the 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 a revision of IEEE 802.11. This revision, called IEEE 802.11be (i.e., Extremely High Throughput (EHT)), was created to support improvements in the peak PHY speed of the corresponding WLAN. Considering IEEE 802.11b through 802.11ac, the peak PHY speed has increased by only 5 to 11 times, as shown in Figure 6, which presents 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 improvements (Bx) for IEEE 802.11be may depend on the maximum MCS (e.g., 4,096QAM and its coding rate).

[0094] IEEE 802.11be primarily focuses on the 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 speed, several candidate features are discussed. These candidate features include (1) more efficient use of 320 MHz bandwidth and discontinuous spectrum, (2) multiband / multichannel aggregation and operation, (3) enhancements to 16 spatial streams and multiple input multiple output (MIMO) protocols, (4) multi-access point (AP) coordination (e.g., coordinated transmission and co-transmission), (5) enhanced link matching and retransmission protocols (e.g., Hybrid Automatic Retransmission Request (HARQ)), and (6) compliance with regulatory rules specific to the 6 GHz spectrum.

[0095] Some features, such as increased bandwidth and the number of spatial streams, have proven effective in previous projects focused on improving link throughput, and their feasibility has been demonstrated, making them achievable solutions.

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

[0097] In some embodiments, the transmitting STA generates a PPDU frame and sends it to the receiving STA. The receiving STA receives, detects, and processes the PPDU. The PPDU may be an EHT PPDU including legacy portions (e.g., legacy short training field (L-STF), legacy long training field (L-LTF), and legacy signal (L-SIG) field), EHT signal A field (EHT-SIG-A), EHT signal B field (EHT-SIG-B), EHT hybrid automatic repeat request field (EHT-HARQ), EHT short training field (EHT-STF), EHT long training field (EHT-LTF), and EHT-DATA field. Figure 7 includes Table 700 describing the fields of the EHT frame format. In particular, Table 700 describes the various fields that may be present within the PHY preamble, data fields, and midamble of the EHT frame format.For example, Table 700 includes the Legacy Short Training Field (L-STF) 712, Legacy Long Training Field (L-LTF) 714, Legacy Signal Field (L-SIG) 716, Repeated L-SIG (RL-SIG) 718, Universal Signal Field (U-SIG) 720, EHT Signal Field (EHT-SIG) 722, EHT Hybrid Auto Retransmission Request Field (EHT-HARQ) 724, EHT Short Training Field (EHT-STF) 726, EHT Long Training Field (EHT-LTF) 728, EHT Data Field 730, and EHT Midamble Field (EHT midamble This includes definitions 702 relating to one or more of field:EHT-MA)732, time length 704, discrete Fourier transform (DFT) period 706, guard interval (GI) 708, and subcarrier interval 710.

[0098] Due to the distributed nature of channel access networks such as IEEE 802.11 wireless networks, carrier sense mechanisms are crucial for collision-free operation. A physical carrier sense mechanism on one STA is responsible for detecting transmissions from other STAs. However, in some situations, detecting each individual case may be impossible. For example, an STA located at a long distance from another STA may assume its medium is idle and begin transmitting a frame while the other STA is also transmitting. Network allocation vectors (NAVs) can be used to overcome this hidden node. However, as wireless networks evolve to include simultaneous transmission / reception between multiple users within a single basic service set (BSS), such as cascaded uplink (UL) / downlink (DL) multi-user (MU) transmissions, mechanisms to enable such situations may be needed. As used herein, multi-user (MU) transmission refers to a case where multiple frames are transmitted simultaneously to or from multiple STAs using different resources. Examples of different resources include different frequency resources in OFDMA transmissions and different spatial streams in MU-MIMO transmissions. Therefore, DL-OFDMA, DL-MU-MIMO, UL-OFDMA, and UL-MU-MIMO are examples of MU transmission.

[0099] Wireless network systems may rely on retransmitting a Medium Access Control (MAC) protocol data unit (MPDU) if the transmitter (TX) has not received an acknowledgment from the receiver (RX), or if the MPDU has not been successfully decoded by the receiver. Using an Automatic Retransmission Request (ARQ) technique, the receiver discards the last failed MPDU before receiving the newly retransmitted MPDU. With the need for improved reliability and reduced latency, wireless network systems may evolve to a hybrid ARQ (HARQ) technique.

[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 the retransmitted signal is the same as the previously failed signal. Puncture is necessary to remove some of the parity bits after encoding with error correction codes. The reason the same puncturing pattern is used in CC-HARQ is that it generates a data sequence coded using forward error correction (FEC), and the receiver uses maximum-ratio combining (MRC) to combine the received retransmitted bits with the same bits from the previous transmission. For example, an information sequence is transmitted in a packet of fixed length. Error correction and detection are performed throughout the packet at the receiver. However, the ARQ scheme can be inefficient when burst errors occur. To solve this more efficiently, subpackets are used. In subpacket transmission, only the subpacket containing the error needs to be retransmitted.

[0101] The receiver uses both the current and previously received subpackets to decode the data, so the probability of error in decoding decreases as the number of subpackets used increases. The decoding process terminates when it passes a cyclic redundancy check (CRC) and the entire packet has been decoded without errors or when the maximum number of subpackets has been reached. In particular, this scheme operates with a stop-and-wait protocol so that the receiver sends an acknowledgment (ACK) to the transmitter if it can decode the packet. 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 the 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 original transmitted subpacket. IR-HARQ alternates between two puncturing patterns for odd-numbered and even-numbered transmissions. The redundancy of IR-HARQ improves the log likelihood ratio (LLR) of the parity bits to synthesize information sent across different transmissions due to a request, and reduces the coding rate as additional subpackets are used. As a result, the subpacket error rate is lower compared to CC-HARQ. The puncturing patterns used in IR-HARQ are indicated by a subpacket identity (SPID) directive. 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. Self-decoding is possible if the signal-to-noise ratio (SNR) environment on the receiving end is good (i.e., high SNR). In some embodiments, the subpackets to be transmitted, each with a corresponding SPID, are in increasing SPID order, but all but the first SPID are interchangeable / switchable.

[0103] To improve WLAN systems, AP cooperation is being discussed as a potential technology to be adopted in IEEE 802.11be, and there are various high-level classifications depending on the AP cooperation method. For example, there is a first type of cooperation method in which user-facing data is transmitted from a single AP (sometimes called "coordinated"), and a second type of cooperation method in which user-facing data is transmitted from multiple APs (sometimes called "joint").

[0104] In the coordinated method, multiple APs either 1) transmit on the same frequency resource based on coordination, creating a spatial null to enable simultaneous transmission from multiple APs, or 2) transmit on orthogonal frequency resources by coordinating and dividing the spectrum, making more efficient use of the spectrum. In the collaborative method, multiple APs transmit jointly to a given user.

[0105] As mentioned above, traditional WLANs allow stations to occupy a channel or link for relatively long periods (for example, by granting a Transmit Opportunity (TXOP) to an STA) in order to avoid the need to compete with other STAs for channel access. However, this feature of traditional WLANs makes it difficult for low-latency applications or STAs to acquire channel access opportunities, thereby making it difficult to meet stringent latency requirements.

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

[0107] Figure 8 shows a scenario in which the AP has low-latency data to transmit to STAn-1 during the uplink TXOP of STA1, according to several embodiments.

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

[0109] After the SIFS interval, STA1 may send data frame 815 (including non-LL data) to the AP during STA1's (uplink) TXOP. While the AP is receiving data frame 810 from STA1, the AP may determine that it has low-latency data 820 that needs to be urgently sent 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 the SIFS interval, AP may send a block ACK frame 825 to STA1 acknowledging data frame 815. After the SIFS interval, 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 the 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 have preempted or intercepted STA1's TXOP in order to send 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 send to STAn-1. As a result, there is no way for the AP to send low-latency data to STAn-1 during STA1's TXOP (because the AP is not permitted to ignore the Tx / Rx (transmit / receive) process between the AP and STA1 during STA1's TXOP). In other words, the conventional WLAN mechanism does not allow the AP to send low-latency data frames 830 to STAn-1 during STA1's TXOP.

[0113] To allow an AP to transmit low-latency data to STAn-1 during STA1's TXOP, the following features may be desirable: (1) STA1 should be able to directly or indirectly recognize that an AP has low-latency data to transmit during STA1's TXOP; and (2) if STA1's TXOP is preempted (taken over by an AP and / or STAn-1) by an 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 Feature 1

[0114] Figure 9 shows how, in several embodiments, an AP may preempt the TXOP of STA1 in order to transmit low-latency data.

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

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

[0117] After the SIFS interval, the AP may send a block ACK frame 925 to the STA1 acknowledging the data frame 915. The block ACK frame 925 may include an instruction that the STA1 should withhold its transmission because the AP has low-latency data to transmit. This instruction may function as a preemption request indicator to show that preemption of the TXOP is requested in order to transmit the low-latency data.

[0118] In one embodiment, the instruction is included in a field of the preamble of the block ACK frame 925. For example, the instruction may be included in the U-SIG field or the UHR-SIG field of the preamble (UHR stands for ultra-high reliability). In one embodiment, the instruction is included in a field of the media access control (MAC) protocol data unit (PDU) of the block ACK frame 925.

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

[0120] Upon receiving a block ACK frame 925 from the AP, STA1 may recognize that the AP has low-latency data to transmit, based on the instructions contained in the block ACK frame 925 (for example, this may be contained in the preamble of the block ACK frame 925 or the MPDU of the block ACK frame 925). As a result, STA1 may postpone its transmission. For example, STA1 may postpone its transmission by deciding not to transmit data following the transmission of the block ACK frame 925 using an SIFS interval, but it may also use a longer IFS interval, such as a PIFS interval or a DIFS interval.

[0121] Following the SIFS interval after AP transmits block ACK frame 925, AP may transmit low-latency data frame 930 (containing low-latency data) to STAn-1. In this way, AP can preempt STA1's TXOP to transmit low-latency data to STAn-1.

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

[0123] The use of different IFS intervals offers benefits in cases where the AP fails to transmit low-latency data frame 930 for any reason. For example, if the AP fails to transmit low-latency data frame 930, STA1 can still transmit data frame 935 (e.g., after the PIFS or DIFS interval), thereby maintaining STA1's TXOP. If the channel is occupied through the use of the RTS / CTS protocol, other STAs are not allowed to access the channel during the PIFS interval time. In other words, 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] Figure 10 shows the interpretation of bits B20-B23 of the U-SIG field according to several embodiments.

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

[0126] Bits B21-B23 may be used to indicate the low latency level of low-latency data. The low latency level of low-latency data indicates the urgency or transmission priority level of the data.

[0127] Bit B20 can be used to indicate whether the low-latency level applies to the current frame or to a future frame. As shown in the diagram, setting bit B20 to "0" may indicate that the low-latency level applies to data contained in the current data frame, while setting bit B20 to "1" may indicate that the low-latency level applies to data contained in a future frame.

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

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

[0130] In one embodiment, the same bit encoding / interpretation or similar 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 said low-latency data.

[0131] Figure 11 shows a block ACK frame format according to several embodiments. As shown in the figure, 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] Figure 12 shows a BA control field format according to several embodiments. As shown in the figure, 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 (group cast 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, an instruction that the AP has low-latency data to transmit is included in the reserved subfield of the BA control field. The BA control field is a field of the block ACK frame (which is the MAC control frame). Scenario 1 Function 2

[0134] Figure 13 shows that in some embodiments, the TXOP of STA1 is extended to compensate for the preemption of the TXOP of STA1.

[0135] Figure 13 is identical to Figure 9, except that it shows that STA1's TXOP can be extended, and that the length of such extension is equal to the length of preemption of STA1's TXOP. In the example shown in the figure, STA1 acquired its TXOP through fair competition with other STAs. However, in order to support the AP's low-latency data transmission, STA1 allowed the AP to preempt STA1's TXOP. Since STA1 allowed the AP to preempt STA1's TXOP, STA1 should be rewarded / compensated by an extension of its TXOP corresponding to the length of time that STA1's TXOP was preempted by the AP and / or other STAs. For this purpose, 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., time length).

[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 intercept the low-latency data frame 930. Also, other STAs may intercept the block ACK frame 940 transmitted by STAn-1. Based on the preamble of the low-latency data frame 930, STA1 may calculate the length of time it takes for the AP to transmit the low-latency data frame 930 to STAn-1. STA1 may determine the TXOP compensation length by summing the "time of the stolen TXOP time" and the "time of the remaining TXOP time" ("remaining TXOP time" may be the length of time the TXOP was left before it was preempted). In the example shown in the figure, (since the end time of BA frame 940 coincides with the end time of STA1's TXOP) there is no "remaining TXOP time length," and therefore STA1 can only consider the "lost TXOP time length" and be rewarded by an extension corresponding to the "lost TXOP time length."

[0137] In one embodiment, STA1 determines the length of a 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 UHR PPDU preamble to support backward compatibility. The L-SIG field may include a velocity 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 of the L-SIG field (e.g., bits B5-B16).

[0138] In one embodiment, STA1 determines the length of a 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 preambles from Wi-Fi® 7 (IEEE 802.11be) onward and in 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 the PHY version identifier field, UL / DL field, TXOP field, and others. STA1 can estimate the channel occupancy time by decoding the TXOP field (e.g., bits B13-B19) of the U-SIG field.

[0139] Therefore, STA1 can determine the length of the low-latency data frame 930 by decoding the L-SIG field or U-SIG field of the preamble of the low-latency data frame 930. STA1 can store this value in its buffer. Please understand that other methods may exist for STA1 to determine / estimate the length of the low-latency data frame 930.

[0140] If 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 because it is part of the same BSS as STAn-1. STA1 may determine the length of the block ACK frame 140 by decoding the L-SIG field or U-SIG field of the preamble of the block ACK frame 140. STA1 may then determine the total TXOP compensation length by adding the lengths of the low-latency data frame 930 and the block ACK frame 940 (and any IFS interval lengths). 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 formula, "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 can refer to the length of time.

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

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

[0144] Figure 14 shows how STA1 extends its TXOP using a CTS to self frame in several embodiments.

[0145] In the example shown in the figure, the AP and STA transmit frames 920-940 as described with reference to Figure 9. In one embodiment, STA1 extends its TXOP using a CTS to self frame. For example, as shown in the figure, after STAn-1 sends a block ACK frame 940 to the AP, STA1 may extend its own TXOP by sending a CTS to self frame 1405 to compensate for its preempted TXOP (e.g., preempted by the AP). If STA1 sends a CTS to self frame 1405, other STAs that intercept the CTS to self frame 1405 may set their Network Allocation Vector (NAV) values ​​to protect STA1's transmit / receive. Thus, the use of the CTS to self frame 1405 helps ensure the extension of STA1's TXOP. After the 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 TXOP may be applied to other scenarios described below. Scenario 2: STAn has low-latency data to transmit during STA1's uplink TXOP.

[0147] Figure 15 shows a scenario in which STAn has low-latency data to transmit to AP during STA1's uplink TXOP, according to several embodiments.

[0148] As shown in the diagram, after the DIFS interval, STA1 may transmit RTS frame 1505. After the SIFS interval, AP may transmit 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] Following the SIFS interval after the transmission of data frame 1515, AP may send a block ACK frame 1530 to STA1 acknowledging data frame 1515. After the SIFS interval, AP may send a trigger frame (TF-R) 1535 scheduling a random access uplink transmission. After the SIFS interval, STAn may send AP a low-latency data frame 1540 containing low-latency data during a random access uplink transmission. After the SIFS interval, AP may send STAn a multi-block ACK frame 1545 acknowledging low-latency data frame 1540.

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

[0152] To allow other STAs to transmit low-latency data during STA1's TXOP, the following features 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 STAs should be selected through fair competition to transmit the low-latency data; and (2) If STA1's TXOP is preempted by another STA to transmit low-latency data (e.g., taken by STAn), 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 Feature 1

[0153] Figure 16 shows how, in several embodiments, STAn may preempt the TXOP of STA1 in order to transmit low-latency data.

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

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

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

[0157] Following the SIFS interval after receiving data frame 1615, AP may send a block ACK frame 1630 to STA1 acknowledging data frame 1615.

[0158] When an AP receives data frame 1615 from STA1, it may determine (based on the instructions contained in data frame 1615) that STA1 has low-latency data to transmit. However, to determine whether any other STA has more urgent low-latency data to transmit, the AP may transmit TF-R frame 1635 to schedule a random access uplink transmission (for example, TF-R frame 1635 may allocate a random access resource unit (RU)). Therefore, when STA1 transmits data frame 1615 to the AP, STA1 may indicate in data frame 1615 whether or not STA1 has low-latency data to transmit. When the AP receives data frame 1615 from STA1, the AP may determine whether polling is necessary to support the request for low-latency data. If the AP determines that polling is necessary, the AP may transmit TF-R frame 1635 to request low-latency data from the STA.

[0159] Multiple STAs receiving TF-R frame 1635 may determine whether they are permitted to transmit their own low-latency data to the AP during random access uplink transmission, based on the low-latency level of their own low-latency data and the low-latency level of STA1's low-latency data (for example, these may be determined based on intercepting STA1's data frame 1615). In one embodiment, an STA may determine that it is not permitted to participate in random access uplink transmission if its low-latency data is not as urgent as STA1's low-latency data. The decision of which STA is given the opportunity to transmit low-latency data during random access uplink transmission may be based on the low-latency levels of the low-latency data among multiple STAs and fair competition among those STAs. In the example shown in the figure, it is assumed that STAn has the most urgent low-latency data, and therefore STAn transmits low-latency data frame 1640 to the AP during random access uplink transmission (after the SIFS interval following the transmission of TF-R frame 1635).

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

[0161] An STA receiving TF-R frames 1635 may determine, according to a predetermined function / algorithm, whether they are permitted to be transmitted during random access uplink transmission. For example, an 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. If the resulting OBO value is greater than or equal to a predefined threshold, the STA may determine that it is permitted to be transmitted during random access uplink transmission; if the resulting OBO value is less than a predefined threshold, the STA may determine that it is not permitted to be transmitted during random access uplink transmission. If permitted to do so during a random access uplink transmission, the STA may use a random access resource unit to transmit its low-latency data to the AP during the random access uplink transmission (for example, a random access resource unit may be specified in TF-R frame 1635).

[0162] As an example in the context of the situation shown in Figure 16, a TF-R frame 1635 transmitted by the AP may indicate that there is one available random access resource unit, and the STA 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 with low-latency level 6 (e.g., most urgent data), and that the low-latency level is used as the OCW value. Each STA may determine its OBO value by randomly selecting an integer between 0 and its OCW value. In this example, it is assumed that the OBO value of STA1 is 3, the OBO value of STAn-1 is 2, and the OBO value of STAn 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 random access resource unit available for random access uplink transmission. Therefore, the OBO value of STA1 becomes 4, the OBO value of STAn-1 becomes 3, and the OBO value of STAn becomes 7 (i.e., each OBO value is incremented by 1). Each STA can 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 can determine that it is permitted to transmit during random access uplink transmission (its OBO value is greater than or equal to the threshold). Thus, STAn can transmit its low-latency data to the AP using the random access resource unit during random access uplink transmission.

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

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

[0165] 2) OCW_max = the highest low latency level (for example, low latency level 6 as shown in the example in Figure 10);

[0166] 3) OBO = random_integer(0, OCW_min) (i.e., a random integer between 0 and OCW_min) (for example, the OBO for STA1, STA2, and STA3 could 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 a random access resource unit (because STA3's OBO is greater than 2), but STA1 and STA2 cannot).

[0168] 5) The threshold_value is set to a predetermined value (for example, 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 selects one of the random access resource units to use for data transmission if the sum is greater than or equal to the threshold_value (for example, neither STA1 nor STA2 can transmit low-latency data because their respective sums (OBO + number of random access resource units) are greater than or equal to the threshold_value, and 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] While the specific methods for determining / defining OBO values, OCW values, and predefined thresholds are described above, please understand that these values ​​may be determined / defined in other ways.

[0171] If only one random access resource unit is available and multiple STAs have OBO values ​​exceeding a predefined threshold, a resource unit collision may occur, and transmission of low-latency data may fail. Furthermore, even if the number of STAs with OBO values ​​exceeding a predefined threshold is less than the number of available random access resource units, a scenario may still exist where multiple STAs select / use the same random access resource unit. Similarly, in this case, a resource unit collision may occur, and transmission of low-latency data may fail. In one embodiment, the AP may send a multiuser block ACK (MU-BA) frame to notify the STA whether the transmission of low-latency data was successful. In one embodiment, if the transmission of low-latency data fails, the STA may reset their OCW and OBO values ​​and repeat the process described above to transmit the 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 will be set to OCW_max;

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

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

[0177] Figure 17 shows pseudocode for determining whether an STA is permitted to transmit during an (OFDMA) random access uplink transmission, according to several embodiments.

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

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

[0180] Otherwise, if this is not the first transmission (for example, if it is a retransmission because the initial transmission failed), OCW is set to a value that is one increment of the previous OCW.

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

[0182] OBO then checks the number of resource units (N). RU ) is incremented by only that amount. STA selects a random resource unit to use for low-latency data transmission if OBO is greater than or equal to a predefined threshold. Scenario 2 Function 2

[0183] Figure 18 shows that in some embodiments, the TXOP of STA1 is extended to compensate for the preemption of the TXOP of STA1.

[0184] Figure 18 shows the same AP-STA interaction as in Figure 16 (starting with data frame 1615), except that it shows that STA1's TXOP can be extended and the length of the extension is equal to the length of the preemption of STA1's TXOP. STA1's TXOP was preempted after STA1 received block ACK frame 1630. STA1 can 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 (and 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 the CTS to self frame described above). Scenario 3: STA has low-latency data to transmit during AP's downlink TXOP.

[0185] Figure 19 shows a scenario in which the STA has low-latency data to transmit to the AP during the AP's downlink TXOP, according to several embodiments.

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

[0187] After the SIFS interval, AP may send data frame 1920 (including non-LL data) to STA1 during AP's TXOP. While AP is sending 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 they urgently need to send to AP. As previously mentioned, what is considered low-latency data may depend on the specific implementation.

[0188] In conventional WLAN mechanisms, the access point (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 transmitting and periodically check the STAs to see if they have low-latency data to transmit. However, it is highly inefficient for the AP to stop transmitting and check for low-latency data that may or may not exist.

[0189] To allow the STA to send low-latency data to the AP during the AP's TXOP, the following features may be desirable: (1) The AP should be able to directly or indirectly recognize that the STA may have low-latency data to send; and (2) If the AP's TXOP is preempted by the STA to send 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 Feature 1

[0190] Figure 20 shows how, in several embodiments, an STAn may preempt the AP's TXOP to transmit low-latency data.

[0191] As shown in the diagram, after the DIFS interval, AP may transmit RTS frame 2005. After the SIFS interval, STA1 may transmit 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 intended for STA1 (including non-LL data) and a trigger frame portion that schedules uplink transmissions and random access uplink transmissions by STA1. While the AP transmits the combined data frame and trigger frame 2015, STAn-1 and STAn may determine that they have low-latency data that they need to urgently transmit to the AP (low-latency data 2020 and low-latency data 2025, respectively). 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 response function). If any STA has low-latency data to transmit, they may transmit the low-latency data using the OFDMA transmission scheme with the resource units allocated by the trigger frame portion of the combined data frame and trigger frame 2015. Therefore, the combined data frame and trigger frame 2015 can be considered instances of the combined data frame and preemption request response frame.

[0193] Following the SIFS interval after the transmission of the combined data frame and trigger frame 2015, STA1 may use the resource units allocated to STA1 by the combined data frame and trigger frame 2015 to send a block ACK frame 2030 to the AP acknowledging the data frame portion of the combined data frame and trigger frame 2015.

[0194] STAs (e.g., STAn-1 and STAn) that have low-latency data to send to the AP may determine (for example, using the OCW / OBO algorithm described above when describing Scenario 2) whether they are permitted to send low-latency data during a random access uplink transmission. STAs permitted to send low-latency data may, during a random access uplink transmission, send a low-latency data frame (containing the low-latency data) to the AP using the combined data frame and random access resource units allocated by the trigger frame 2015.

[0195] In the example shown in the figure, it is assumed that the combined data frame and the trigger frame portion of trigger frame 2015 are allocated two resource units for uplink transmission: the first resource unit (RU1) is allocated to STA1, and the second resource unit (RU2) is allocated to the random access resource unit. In this example, it is also assumed that STAn determines that it is permitted to transmit low-latency data during random access uplink transmission (for example, because it has more urgent data to send to the AP compared to STAn-1). Therefore, STA1 sends block ACK frame 2030 to the AP using RU1, and STAn sends low-latency data frame 2035 to the AP using RU2. The transmission of block ACK frame 2030 and low-latency data frame 2035 may be simultaneous (for example, using the uplink OFDMA transmission technique).

[0196] Following the SIFS interval following the simultaneous transmission of block ACK frame 2030 and low-latency data frame 2035, the AP may transmit a multiblock ACK frame 2040 acknowledging block ACK frame 2030 and low-latency data frame 2035. In one embodiment, the AP transmits a combined data frame and multiblock ACK frame instead of a multiblock ACK frame. The combined data frame and multiblock ACK frame may include a data frame portion intended for the STA, as well as a multiblock ACK frame portion acknowledging block ACK frame 2030 and low-latency data frame 2035.

[0197] In one embodiment, if STA1 determines (before sending block ACK frame 2030) that it has low-latency data to send, STA1 may include an instruction in block ACK frame 2030 indicating that AP should postpone its transmission because STA1 has low-latency data to send (similar to the instruction included in block ACK frame 925 in Figure 9, for example). In this case, STA1 may send a low-latency data frame (containing the low-latency data) to AP after an SIFS interval following the transmission of block ACK frame 2030, and AP may postpone the transmission by using a longer IFS interval (e.g., a PIFS interval or DIFS interval). Thus, the combined data frame and the trigger frame portion of trigger frame 2015 can be interpreted as equivalent to querying multiple STAs whether they have low-latency data. An STA with low-latency data to send (e.g., STA1) may respond by sending a frame indicating that it has low-latency data to send (e.g., block ACK frame 2030 containing an instruction that STA1 has low-latency data to send).

[0198] Referring to Figure 20, the methods described above offer advantages over other methods. For example, one method to allow STAs to transmit low-latency data during AP's TXOP would be for the AP to periodically send trigger frames, giving STAs the opportunity to send low-latency data to the AP. However, this can lead to resource waste. In the worst case, if no STA has low-latency data to send to the AP, the AP loses the opportunity to send data and wastes resources by sending trigger frames to STAs that will not use the random access uplink transmissions scheduled by the trigger frames, thus terminating the AP's TXOP. This also results in longer idle time for the overall radio resources. From the AP's perspective, there is a benefit in periodically sending trigger frames, which gives STAs the opportunity to send low-latency data, but from the perspective of overall system performance, this is a significant loss because no meaningful action is taken if STAs do not have low-latency data to send. In contrast, with the method using combined data frames and trigger frames described above, even if no STA has low-latency data to send to the AP, other STAs within the same BSS can transmit non-LL data. In other words, even if there are no STAs with low-latency data to transmit, an STA can still transmit non-LL data to the AP during random access uplink transmission (e.g., using a random access resource unit). Furthermore, a TXOP can be obtained if the AP does not terminate prematurely. Scenario 3 Function 2

[0199] Figure 21 shows how, in some embodiments, the AP's TXOP is extended to compensate for the AP's TXOP being preempted.

[0200] Figure 21 shows the same AP-STA interaction as in Figure 20, except that it shows that the AP's TXOP can be extended and that the length of such extension is equal to the length of the AP's TXOP preemption. The AP may determine the TXOP compensation length based on the length of the combined data frame and the trigger frame portion of the trigger frame 2015, the increase in transmission time due to the use of uplink OFDMA (e.g., splitting resource units instead of allowing the block ACK frame 2030 to be received using the entire bandwidth), and the length of the multiblock ACK frame 2040. For example, the AP may determine the TXOP compensation length by summing these lengths (and any IFS interval). Following the transmission of the multiblock ACK frame 2040 by the AP, the AP may extend its TXOP by the TXOP compensation length (e.g., using the CTS to self frame described above).

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

[0202] In addition, although shown in a specific 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, although the operations of Method 2200 are shown in a sequential order, some of the operations may be performed in overlapping periods, either partially or entirely.

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

[0204] In response to operation 2205, in which the AP has determined that it has low-latency data to transmit, the AP radio transmits a block acknowledgment (BA) frame to the first STA acknowledging the data frame, the BA frame including an instruction 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 instruction that the AP has low-latency data to transmit is included in a field of the BA frame's preamble. In one embodiment, the field of the preamble is the U-SIG field. In another embodiment, the field of the preamble is the UHR-SIG field. In one embodiment, the instruction that the AP has low-latency data to transmit is included in the MPDU field of the BA frame. In one embodiment, this field is included in the BA control field of the BA frame. In one embodiment, the instruction 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 one bit is used to indicate whether the low latency level relates to low latency data contained in the current frame or to low latency data contained in a future frame.

[0205] In operation 2215, following the 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 frame interval following the transmission of the BA frame, where the first frame interval is shorter than a second frame interval that will be used by the first STA following the transmission of the BA frame. In one embodiment, the BA frame contains an instruction that the AP has low-latency data to transmit, causing the first STA to use the second frame interval when attempting to access the wireless channel. In one embodiment, the first frame interval is an SIFS interval, and the second frame 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 frame interval following the transmission of the BA frame due to a failure to transmit the low-latency data frame. In one embodiment, the second STA is the same as the first STA.

[0206] In one embodiment, during operation 2220, the AP wirelessly receives a second BA frame from the second STA that acknowledges a low-latency data frame.

[0207] Now, looking at Figure 23, a method 2300 performed by the first STA to allow the AP to transmit low-latency data is described according to an exemplary 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 response to operation 2315 determining that the BA frame contains an instruction that the AP has low-latency data to transmit, the first STA uses a second frame interval instead of a first frame interval when attempting to access the radio channel, where the second frame interval is longer than the first frame interval.

[0211] In one embodiment, in operation 2320, the first STA determines the 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 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 U-SIG field of the preamble of the BA frame.

[0212] In one embodiment, in operation 2325, the first STA extends the TXOP of the first STA by the TXOP compensation length. In one embodiment, operation 2325 is accompanied by operations 2330-2340.

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

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

[0215] In operation 2405, the first STA radio-transmits a data frame to the AP during the first STA's TXOP, the data frame including an instruction 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] In operation 2415, the first STA receives a trigger frame from the AP after radio receiving the first BA frame, where the trigger frame schedules a random access uplink radio transmission, and one of the other STAs radio transmits a low-latency data frame to the AP during the random access uplink radio transmission.

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

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

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

[0221] In operation 2505, the first STA intercepts a radio transmission of a data frame to the AP by the second STA during the second STA's TXOP, the data frame containing an instruction that the second STA has low-latency data to transmit.

[0222] In 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] In operation 2520, in response to receiving a trigger frame, the first STA determines whether to radio transmit the first STA's low-latency data to the AP during random access uplink radio transmission, based on the low-latency levels of the first STA's low-latency data and the low-latency levels of the second STA's low-latency data.

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

[0225] Now, looking at Figure 26, a method 2600 performed by a first STA to determine whether to wirelessly transmit low-latency data to an AP during random access uplink wireless transmission is described according to an exemplary 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 from the first STA to the AP during random access uplink wireless transmission).

[0227] In operation 2605, the first STA determines the OFDMA backoff value (also referred to herein as the OBO value) based on the low latency level of the first STA's low latency data. Operation 2605 may be accompanied by operations 2610 and 2615. In operation 2610, the first STA sets the OFDMA conflict window value based on the low latency level of the first STA's low latency data. In operation 2615, the first STA randomly selects an integer value between zero and the OFDMA conflict window value to be the OFDMA backoff value.

[0228] In 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] In operation 2625, the first STA determines whether the incremented OFDMA backoff value is greater than or equal to a threshold. If the incremented OFDMA backoff value is greater than or equal to a threshold, the first STA determines in operation 2630 that it is to transmit low-latency data wirelessly. Otherwise, if the incremented OFDMA backoff value is not greater than or equal to a threshold, the first STA determines in operation 2635 that it is not to transmit low-latency data wirelessly.

[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 increments the previous OFDMA competition window value to generate an incremented OFDMA competition window value. The first STA may then randomly select an integer value between zero and the incremented OFDMA competition window value to set as the OFDMA backoff value. Based on the selected value, the first STA may then determine whether to wirelessly transmit low-latency data during the next random access uplink wireless transmission.

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

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

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

[0234] In operation 2715, the AP radio transmits multiblock ACK frames to the first and second STAs acknowledging the BA frame and the low-latency data frame. In one embodiment, the multiblock ACK frame is a combined data and multiblock ACK frame, including a second data frame portion intended for the first STA.

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

[0236] In one embodiment, in operation 2725, the AP extends its TXOP by the TXOP compensation length. In one embodiment, operation 2725 is accompanied by operations 2730-2740. In operation 2730, the AP wirelessly transmits a CTS to self frame. In operation 2735, after wirelessly transmitting the CTS to self frame, the AP wirelessly transmits a data frame to the STA. In operation 2740, after wirelessly transmitting the data frame, the first STA wirelessly receives an ACK frame from the STA acknowledging the data frame.

[0237] Now, looking at Figure 28, a method 2800 performed by the first STA to allow the second STA to transmit low-latency data during the AP's TXOP is described according to an exemplary embodiment. The first STA may be implemented by a wireless device.

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

[0239] In operation 2810, in response to receiving a combined data frame and trigger frame from the AP, the first STA uses its first resource unit to wirelessly transmit a BA frame to the AP acknowledging the data frame portion of the combined data frame and trigger frame, where the second STA uses its second resource unit to wirelessly transmit a low-latency data frame to the AP during 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 instruction that the AP should withhold its transmission because it contains low-latency data for the first STA to transmit.

[0240] Now, looking at Figure 29, a method 2900 performed by a first STA to transmit low-latency data during the AP's TXOP is described according to an exemplary embodiment. The first STA may be implemented by a wireless device.

[0241] In 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 include a data frame portion intended for the second STA and a trigger frame portion that schedules an uplink wireless transmission and a random access uplink wireless transmission by the second STA, which are to be performed simultaneously.

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

[0243] In operation 2915, the first STA, during random access uplink radio transmission, uses the first resource unit to radio-transmit a low-latency data frame containing low-latency data to the AP, while the second STA, during uplink radio transmission by the second STA, uses the second resource unit to radio-transmit a BA frame to the AP. 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 and wired networks. In some embodiments, the solutions and techniques provided herein may be a product in which instructions for programming one or more data processing components (collectively referred to herein as “processors” or “processing units”) to perform the operations described herein are stored in a non-temporary machine-readable medium (such as microelectronic memory), or may be embodied therein. 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). Alternatively, these operations may be performed by any combination of programmed data processing components and fixed hardwired circuit components.

[0245] In some cases, an embodiment may be a device (e.g., APSTA, non-APSTA, or another network or computing device) comprising one or more hardware and software logic structures for performing one or more of the operations described herein. For example, as described herein, the device may include a memory unit storing instructions that can be executed by a hardware processor installed in the device. The device may also include one or more other hardware or software elements, such as a network interface or a display device.

[0246] Some parts of the detailed explanations above are presented in terms of algorithms and symbolic representations of operations on data bits in computer memory. These descriptions and representations of algorithms are the methods used by those skilled in the field of data processing to most effectively communicate the content of their research to others skilled in the field. Here, and generally, an algorithm is considered to be a consistent set of operations that produce a desired result. These operations require physical operations on physical quantities. These quantities usually, though not always, take the form of electrical or magnetic signals that can be stored, combined, compared, and otherwise manipulated. It has proven to be more convenient in some cases to refer to these signals as bits, values, elements, symbols, characters, terms, numbers, or the like, primarily because they are commonly used.

[0247] However, it should be kept in mind that all of these and similar terms will be associated with appropriate physical quantities and are merely convenient labels applied to those quantities. This disclosure may refer to actions and processes of computer systems or other similar electronic computing devices that manipulate data represented as physical (electronic) quantities in the registers and memory of the computer system and convert them into other data similarly represented as physical quantities in the memory or registers of the computer system or other such information storage systems.

[0248] This disclosure also relates to an apparatus for performing the operations described herein. This apparatus may be constructed specifically for the intended purpose, or it may include a general-purpose computer that is selectively invoked or reconfigured by a computer program stored in the computer. For example, a computer system or other data processing system may perform the computer implementation methods described herein in response to its processor executing a computer program (e.g., a set of instructions) contained in memory or other non-temporary machine-readable storage medium. Such computer programs may be stored in computer-readable storage media, each coupled to a computer system bus, such as any type of disk including floppy disks, optical disks, CD-ROMs, and magneto-optical disks, read-only memory (ROM), random access memory (RAM), EPROM, EEPROM, magnetic or optical cards, or any type of medium suitable for storing electronic instructions.

[0249] The algorithms and representations presented herein are not inherently related to any particular computer or other device. Various general-purpose systems may be used with the programs taught herein, or it may be proven that it is more convenient to construct more specialized devices to implement the methods. The structures of these various systems will appear as described below. In addition, this disclosure is not described with reference to any particular programming language. It will be understood that various programming languages ​​may be used to implement the teachings of this disclosure as described herein.

[0250] This disclosure may be provided as a computer program product or software that may include a machine-readable medium storing instructions, and by using such instructions, a computer system (or other electronic device) can be programmed to perform the processes described herein. The machine-readable medium includes any mechanism for storing information in a format readable by a machine (e.g., a computer). In some embodiments, the machine-readable (e.g., computer-readable) medium includes machine (e.g., computer)-readable storage media such as read-only memory ("ROM"), random-access memory ("RAM"), magnetic disk storage media, optical storage media, flash memory components, etc.

[0251] In the above-described specification, embodiments of the Disclosure have been described with reference to specific exemplary embodiments. It will be apparent that various modifications can be made to these embodiments without departing from the broader spirit and scope of the embodiments of the Disclosure described in the following claims. Accordingly, this specification and the drawings should be considered illustrative rather than restrictive. (Other possible items) (Item 1) A method used by a wireless device acting as an access point (AP) within a wireless network to transmit low-latency data: During a transmission opportunity (TXOP) of the first station (STA), a step is to wirelessly receive a data frame from the first STA; Steps include: and, in response to determining that the AP has low-latency data to transmit, wirelessly transmitting a block acknowledgment (BA) frame to the first STA acknowledging the data frame, wherein the BA frame includes an instruction that the first STA should withhold its transmission because the AP has low-latency data to transmit; and Following the transmission of the BA frame, the next step is to wirelessly transmit a low-latency data frame to the second STA. A method for providing this. (Item 2) The method according to item 1, wherein the low-latency data frame is transmitted after a first frame interval following the transmission of the BA frame, where the first frame interval is shorter than a second frame interval which will be used by the first STA following the transmission of the BA frame. (Item 3) The method of item 2, wherein the instruction that the AP has low-latency data to transmit is included in the BA frame, causing the first STA to use a second frame interval when attempting to access a radio channel. (Item 4) The method according to item 3, wherein the first frame interval is a short frame interval (SIFS) interval, and the second frame interval is a point adjustment function frame interval (PIFS) interval or a dispersion adjustment function frame interval (DIFS) interval. (Item 5) The step of wirelessly receiving a data frame from the first STA after the second frame interval following the transmission of the BA frame, due to the failure to transmit the low-latency data frame, The method described in item 2, further comprising the above. (Item 6) The method according to item 1, wherein the instruction that the AP has low-latency data to transmit is included in a field of the preamble of the BA frame. (Item 7) The method according to item 6, wherein the field of the preamble is a universal signal (U-SIG) field. (Item 8) The method according to item 6, wherein the field of the preamble is an ultra-high reliability signal (UHR-SIG) field. (Item 9) The method according to item 1, wherein the instruction that the AP has low-latency data to transmit is included in a field of the Media Access Control (MAC) protocol data unit (PDU) of the BA frame. (Item 10) The field is included in the BA control field of the BA frame, as described in item 9. (Item 11) The instruction that the AP has low-latency data to transmit includes 4 bits, as described in item 1. (Item 12) The method according to item 11, wherein three of the four bits are used to indicate the low latency level of the low latency data, and the remaining one bit of the four bits is used to indicate whether the low latency level relates to low latency data contained in the current frame or to low latency data contained in a future frame. (Item 13) Steps include wirelessly receiving a second BA frame from the second STA that acknowledges the low-latency data frame. The method described in item 1, further comprising the above. (Item 14) The method described in item 1, wherein the second STA is the same as the first STA. (Item 15) A method performed by a wireless device acting as a first station (STA) in a wireless network to allow an access point (AP) to transmit low-latency data: During the first STA's transmission opportunity (TXOP), a step is taken to wirelessly transmit a data frame to the AP; The step of receiving a block acknowledgment (BA) frame from the AP wirelessly, acknowledging the aforementioned data frame; and In response to determining that the BA frame contains an instruction that the AP has low-latency data to transmit, the AP attempts to access the radio channel, and in this step, uses a second frame interval instead of a first frame interval, wherein the second frame interval is longer than the first frame interval. A method for providing this. (Item 16) A step of determining the TXOP compensation length based on the length of the low-latency data frame and the length of the BA frame; and Steps to extend the TXOP of the first STA by the TXOP compensation length. The method described in item 15, further comprising the above. (Item 17) The step of extending the TXOP of the first STA by the TXOP compensation length is: The stage where a transmit permission (CTS) to self frame is transmitted wirelessly; The step of wirelessly transmitting the CTS to self frame, and then wirelessly transmitting the data frame to the AP; and After wirelessly transmitting the data frame, the AP wirelessly receives an acknowledgment (ACK) frame from the AP acknowledging the data frame. The method described in item 16, which has the following characteristics. (Item 18) The method according to item 16, wherein the length of the low-latency data frame is determined based on the legacy signal (L-SIG) field or universal signal (U-SIG) field of the preamble of the low-latency data frame, and the length of the BA frame is determined based on the L-SIG field or U-SIG field of the preamble of the BA frame. (Item 19) A method by which a wireless device acting as a first station (STA) in a wireless network allows other STAs to transmit low-latency data: During the first STA's transmission opportunity (TXOP), a step is taken to wirelessly transmit a data frame to an access point (AP), wherein the data frame includes an instruction that the first STA has low-latency data to transmit; Steps include wirelessly receiving a first block acknowledgment (BA) frame from the AP that acknowledges the aforementioned data frame; After wirelessly receiving the first BA frame, a trigger frame is wirelessly received from the AP, 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; A step of determining the 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 confirms the low-latency data frame and is wirelessly transmitted by the AP to the other STA; and Steps to extend the TXOP of the first STA by the TXOP compensation length. A method for providing this. (Item 20) A method performed by a wireless device acting as a first station (STA) in a wireless network to transmit low-latency data: During a second STA transmission opportunity (TXOP), the system intercepts a radio transmission of a data frame by the second STA to an access point (AP), wherein the data frame includes an instruction indicating that the second STA has low-latency data to transmit; In the step of receiving a trigger frame wirelessly from the AP, the trigger frame schedules a random access uplink wireless transmission; A 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, based on the low-latency level of the low-latency data of the first STA and the low-latency level of the low-latency data of the second STA, in response to receiving the trigger frame; and In response to the first STA determining that it is scheduled to wirelessly transmit the low-latency data of the first STA to the AP during the random access uplink wireless transmission, the random access resource unit attempts to wirelessly transmit a low-latency data frame containing the low-latency data of the first STA to the AP during the random access uplink wireless transmission. A method for providing this. (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 is: 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 available random access resource units in the random access uplink wireless 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 The method according to item 20, comprising the above steps. (Item 22) The step of determining the OFDMA backoff value based on the low-latency level of the low-latency data of the first STA is: 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 The method according to item 21, comprising the above steps. (Item 23) The step of determining the OFDMA backoff value is: In response to determining that the previous attempt to wirelessly transmit the low-latency data frame during the random access uplink wireless transmission failed, incrementing the previous OFDMA contention window value to generate an incremented OFDMA contention window value; and Randomly selecting an integer value between zero and the incremented OFDMA contention window value as the OFDMA backoff value The method according to item 21, comprising the above steps. (Item 24) A method that a wireless device acting as an access point (AP) in a wireless network performs to allow an STA to transmit low-latency data: During the AP's Transmit Opportunity (TXOP), a step is taken to wirelessly transmit a combined data frame and a trigger frame, 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, and the uplink wireless transmission and the random access uplink wireless transmission by the first STA are to be performed simultaneously; During the uplink wireless transmission by the first STA, the first resource unit wirelessly receives a block acknowledgment (BA) frame from the first STA acknowledging the data frame portion of the combined data frame and trigger frame; and during the random access uplink wireless transmission, the second resource unit wirelessly receives a low-latency data frame from the second STA; and Steps include wirelessly transmitting a multiblock ACK frame acknowledging the BA frame and the low-latency data frame to the first STA and the second STA. A method for providing this. (Item 25) A step of determining 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 orthogonal frequency division multiple access (OFDMA) during the uplink radio transmission by the first STA, and the length of the multiblock ACK frame; and The step of extending the TXOP of the AP by the TXOP compensation length. The method described in item 24, further comprising the above. (Item 26) The method according to item 24, wherein the multiblock ACK frame is a combined data and multiblock ACK frame, including a second data frame portion intended for the first STA. (Item 27) A method performed by a first station (STA) in a wireless network to transmit low-latency data: During the AP's Transmit Opportunity (TXOP), the AP wirelessly receives a combined data frame and a trigger frame from the access point (AP), wherein the combined data frame and trigger frame include a data frame portion intended for the first STA and a trigger frame portion that schedules the first STA to perform an uplink wireless transmission and, together with, a random access uplink wireless transmission; and In response to receiving the combined data frame and trigger frame from the AP, the first resource unit wirelessly transmits a block acknowledgment (BA) frame to the AP acknowledging the data frame portion of the combined data frame and trigger frame, wherein the second STA wirelessly transmits a low-latency data frame to the AP using the second resource unit during the random access uplink wireless transmission. A method for providing this. (Item 28) The method of item 27, which includes an instruction that the AP should withhold transmission because the BA frame has low-latency data for the first STA to transmit. (Item 29) A method performed by a first station (STA) in a wireless network to transmit low-latency data: During an access point (AP) transmission opportunity (TXOP), a combined data frame and a trigger frame are wirelessly received from the AP, wherein the combined data frame and trigger frame include 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, and the uplink wireless transmission and the random access uplink wireless transmission by the second STA are to be performed simultaneously; A step of determining whether to transmit data to the AP during the random access uplink radio transmission based on the low latency level of the low latency data that the first STA is to transmit to the AP; and During the random access uplink wireless transmission, the first resource unit wirelessly transmits a low-latency data frame containing the low-latency data to the AP, wherein the second STA wirelessly transmits a block acknowledgment (BA) frame to the AP using the second resource unit during the uplink wireless transmission by the second STA. A method for providing this.

Claims

1. A method performed by a first wireless device within a wireless network: The step of wirelessly receiving a data frame from a second wireless device within the aforementioned wireless network; In response to determining that the first wireless device has low-latency data to transmit, the first wireless device wirelessly transmits an acknowledgment (ACK) frame to the second wireless device acknowledging the data frame, wherein the ACK frame includes an instruction that the second wireless device may consider withholding its transmission because the first wireless device has low-latency data to transmit. A method for providing this.

2. The method according to claim 1, wherein the instruction that the first wireless device has low-latency data to transmit is included in a field of the preamble of the ACK frame.

3. The method according to claim 2, wherein the field of the preamble is a universal signal (U-SIG) field.

4. The method according to claim 2, wherein the field of the preamble is an ultra-high reliability signal (UHR-SIG) field.

5. A method performed by a first wireless device within a wireless network to allow a second wireless device within the wireless network to transmit low-latency data: A step of wirelessly transmitting a data frame to the second wireless device; The steps include: wirelessly receiving an acknowledgment (ACK) frame from the second wireless device that acknowledges the aforementioned data frame; and In response to determining that the ACK frame contains an instruction that the second wireless device has low-latency data to transmit, the step of using a second frame interval instead of a first frame interval when attempting to access the wireless channel, wherein the second frame interval is longer than the first frame interval. A method for providing this.

6. Following the transmission of the ACK frame, the next step is to wirelessly transmit a low-latency data frame to a third wireless device: Furthermore, The third wireless device is either identical to the second wireless device or a different wireless device from the second wireless device. The method according to claim 1.

7. The method according to claim 1, wherein the first wireless device functions as an access point (AP) within the wireless network.

8. The method according to claim 1, wherein the first wireless device functions as a non-access point (AP) station (STA) within the wireless network.

9. The method according to claim 1, wherein the second wireless device is a transmit opportunity (TXOP) holder and the first wireless device is a TXOP responder.

10. The method according to claim 9, wherein the first wireless device functions as an access point (AP) within the wireless network.

11. The method according to claim 9, wherein the first wireless device functions as a non-access point (AP) station (STA) within the wireless network.

12. The method according to claim 1, wherein the ACK frame is a block ACK frame.

13. The method according to claim 12, wherein the instruction that the first wireless device has low-latency data to transmit is included in the medium access control (MAC) field of the block ACK frame.

14. The method according to claim 5, wherein the first wireless device functions as a non-access point (AP) station (STA) in the wireless network, and the second wireless device functions as an AP in the wireless network.

15. The method according to claim 5, wherein the first wireless device functions as an access point (AP) in the wireless network, and the second wireless device functions as a non-AP station (STA) in the wireless network.

16. The method according to claim 5, wherein the first wireless device is a transmit opportunity (TXOP) holder and the second wireless device is a TXOP responder.

17. The method according to claim 16, wherein the first wireless device functions as a non-access point (AP) station (STA) within the wireless network.

18. The method according to claim 16, wherein the first wireless device functions as an access point (AP) within the wireless network.

19. The method according to claim 5, wherein the ACK frame is a block ACK frame.

20. The method according to claim 19, wherein the instruction that the second wireless device has low-latency data to transmit is included in the medium access control (MAC) field of the block ACK frame.

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