Frame exchange sequence for soliciting uplink transmission in distributed tone resource units

Abstract

A method performed by an access point (AP) to solicit an uplink trigger-based physical layer protocol data unit (PPDU) in distributed tone resource units (dRUs). The method includes transmitting an enhanced trigger frame to solicit an enhanced feedback report frame, wherein a station (STA) receiving the enhanced trigger frame is able to determine a dRU assigned to the STA based on information included in the enhanced trigger frame, receiving the enhanced feedback report frame, wherein a preamble field of the enhanced feedback report frame is received in a plurality of dRUs with each of the plurality of dRUs carrying an indication of whether a STA assigned to the dRU has buffered data to transmit, determining STAs that have buffered data to transmit based on decoding the preamble field, and transmitting a trigger frame to solicit the uplink trigger-based PPDU from the STAs that have buffered data to transmit.

Description

SPECIFICATIONFRAME EXCHANGE SEQUENCE FOR SOLICITING UPLINK TRANSMISSION IN DISTRIBUTED TONE RESOURCE UNITSCROSS-REFERENCE TO RELATED APPLICATION

[0001] This application claims the benefit of U.S. Provisional Application No. 63 / 638,862, filed April 25, 2024, titled “Methods for enhancing resource allocation in Distributed Tone RU (dRU)”, which is hereby incorporated by reference.TECHNICAL FIELD

[0002] The present disclosure generally relates to wireless communications, and more specifically, relates to a frame exchange sequence for soliciting uplink transmission in distributed tone resource units (dRUs).BACKGROUND

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

[0004] IEEE 802.1 Ibe, also known as “Wi-Fi 7”, is the next generation of the IEEE 802.11 family of standards for wireless local area networks. Currently under development, 802.1 Ibe aims to significantly improve upon the capabilities of its predecessor, 802.1 lax / Wi-Fi 6, by offering even higher data rates, lower latency, and increased reliability. The standard is expected to leverage advanced technologies such as multi-link operation (MLO), which allows devices to simultaneously use multiple frequency bands and channels for enhanced performance andreliability. Additionally, 802. l lbe will introduce 4096-QAM (Quadrature Amplitude Modulation), enabling higher data rates by encoding more bits per symbol. The standard will also feature improved medium access control (MAC) efficiency, enhanced power saving capabilities, and better support for high-density environments. With these advancements, 802.1 Ibe is expected to deliver theoretical maximum data rates of up to 46 gigabits per second (Gbps), making it suitable for bandwidth-intensive applications such as virtual and augmented reality, 8K video streaming, and high-performance gaming. The IEEE 802.1 Ibe standard is projected to be finalized by the end of 2024, paving the way for the next generation of Wi-Fi devices and networks.

[0005] A distributed tone resource unit (dRU) is a resource unit that is composed of noncontiguous tones that are distributed across a spectrum. This is in contrast to a regular nondistributed tone resource unit (rRU) that is composed of contiguous tones. The use of dRU can improve spectral efficiency by enabling wireless devices to transmit using higher transmit power.

[0006] An access point (AP) may solicit uplink transmission from one or more stations (STAs) that are associated with the AP in dRUs by assigning dRUs to the one or more STAs. However, the AP may not know which STAs have buffered data to transmit and may not know the channel condition of the operating bandwidth, which may prevent the AP from being able to assign dRUs to STAs in an efficient manner.BRIEF DESCRIPTION OF THE DRAWINGS

[0007] The disclosure will be more fully understood from the detailed description provided below and the accompanying drawings that depict various embodiments of the disclosure. However, these drawings should not be interpreted as limiting the disclosure to the specific embodiments shown; they are provided for explanation and understanding only.

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

[0009] Figure 2 is a schematic diagram of a wireless device, in accordance with some embodiments of the present disclosure.

[0010] Figure 3A illustrates components of a wireless device configured to transmit data, in accordance with some embodiments of the present disclosure.

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

[0012] Figure 4 illustrates interframe space (IFS) relationships, in accordance with some embodiments of the present disclosure.

[0013] Figure 5 illustrates a Carrier Sense Multiple Access with Collision Avoidance (CSMA / CA)-based frame transmission procedure, in accordance with some embodiments of the present disclosure.

[0014] Figure 6 illustrates maximum physical layer (PHY) rates for Institute of Electrical and Electronics Engineers (IEEE) 802.11 standards, in accordance with some embodiments of the present disclosure.

[0015] Figure 7 provides a detailed description of fields in Extremely High Throughput (EHT) Physical Protocol Data Unit (PPDU) frames, including their purposes and characteristics, in accordance with some embodiments of the present disclosure.

[0016] Figure 8 illustrates an example of multi-user (MU) transmission in Orthogonal Frequency-Division Multiple Access (OFDMA), in accordance with some embodiments of the present disclosure.

[0017] Figure 9 illustrates an example of an access point sending a trigger frame to multiple associated stations and receiving Uplink Orthogonal Frequency-Division Multiple Access Trigger-Based Physical Protocol Data Units (UL OFDMA TB PPDUs) in response, in accordance with some embodiments of the present disclosure.

[0018] Figure 10 is a diagram showing a regular resource unit assignment in a 80 Megahertz (MHz) bandwidth, according to some embodiments.

[0019] Figure 11 is a diagram showing a distributed tone resource unit assignment in a 80 MHz bandwidth, according to some embodiments.

[0020] Figure 12 is a diagram showing a 80 MHz distributed resource unit (dRU) tone plan that specifies four-tone dRUs, according to some embodiments.

[0021] Figure 13 is a diagram showing an assignment of dRUs to four non-AP stations (STAs) in accordance with a 80 MHz dRU tone plan, according to some embodiments.

[0022] Figure 14 is a diagram showing a format of an enhanced trigger frame, according to some embodiments.

[0023] Figure 15 is a diagram showing enhanced feedback report frames transmitted by non- AP STAs, according to some embodiments.

[0024] Figure 16 is a diagram showing an enhanced null data packet (NDP) feedback report frame as received by the AP, according to some embodiments.

[0025] Figure 17 is a diagram showing a frame exchange sequence between the AP and non- AP STAs, according to some embodiments.

[0026] Figure 18 is a diagram showing a frame exchange sequence for a case where some non- AP STAs do not have buffered data to transmit, according to some embodiments.

[0027] Figure 19 is a diagram showing a frame exchange sequence for a case where an enhanced NDP feedback report frame is not properly received in at least a portion of the bandwidth, according to some embodiments.

[0028] Figure 20 is a diagram showing an 80 MHz bandwidth that is divided into a 20 MHz subblock and a 40 MHz subblock, according to some embodiments.

[0029] Figure 21 is a flow diagram of a method for soliciting an uplink trigger-based PPDU in dRUs, according to some embodiments.

[0030] Figure 22 is a flow diagram of a method for providing feedback information to an AP to allow the AP to solicit an uplink trigger-based PPDU in dRUs, according to some embodiments.DETAILED DESCRIPTION

[0031] The present disclosure generally relates to wireless communications, and more specifically, relates to a frame exchange sequence for soliciting uplink transmission in distributed tone resource units (dRUs).

[0032] As mentioned above, an access point (AP) may solicit an uplink transmission from one or more stations (STAs) that are associated with the AP in dRUs by assigning dRUs to the one or more STAs. However, the AP may not know which STAs have buffered data to transmit and may not know the channel condition of the operating bandwidth, which may prevent the AP from being able to assign dRUs to STAs in an efficient manner.

[0033] The present disclosure introduces a frame exchange sequence between an AP and (non- AP) STAs that allows the AP to determine which (non-AP) STAs have buffered data to transmit to the AP and to determine the channel condition of the operating bandwidth. The frame exchange may involve transmitting new types of frames introduced herein such as an enhanced trigger frame and an enhanced null data packet (NDP) feedback report frame. The AP may use the information obtained from the frame exchange sequence to assign dRUs to STAs in an efficient manner (e.g., only assign dRUs to STAs that have buffered data to transmit and avoid assigning dRUs that span portion(s) of the bandwidth that have poor channel quality) and thus improve the spectral efficiency.

[0034] According to some embodiments, an AP may transmit an enhanced trigger frame to solicit an enhanced feedback report frame. A STA that receives the enhanced trigger frame may be able to determine a dRU assigned to the STA based on information included in the enhancedtrigger frame. The STA may transmit an enhanced feedback report frame to the AP as a response to the enhanced trigger frame, where a preamble field of the enhanced feedback report frame is transmitted in the dRU assigned to the STA and includes an indication of whether the STA has buffered data to transmit. The AP may determine which STAs that have buffered data to transmit based on decoding the preamble of the enhanced feedback report frame. Also, the AP may determine the channel condition of the operating bandwidth based on the enhanced feedback report frame. For example, if the enhanced feedback report frame was not properly received in a portion of a bandwidth, the AP may determine that the portion of the bandwidth in which the enhanced report frame was not properly received has poor channel quality. The AP may generate a dRU assignment that assigns STAs that have buffered data to transmit to dRUs that do not span the portion of the bandwidth in which the enhanced feedback report frame was not properly received (the portion of the operating bandwidth that has poor channel quality). The AP may then transmit a trigger frame to solicit an uplink trigger-based physical layer protocol data units (PPDU) from the STAs that have buffered data to transmit. The AP may include an indication of the dRU assignment in the trigger frame. A STA that receives the trigger frame may transmit an uplink trigger-based PPDU to the AP in the dRU assigned to the STA by the dRU assignment indicated in the trigger frame.

[0035] The frame exchange sequence disclosed herein may allow the AP to determine which STAs have buffered data to transmit and allow the AP to determine the channel condition of the operating bandwidth, which may in turn allow the AP to assign dRUs in an efficient manner. For example, the AP may avoid assigning dRUs to STAs that do not have buffered data to transmit and avoid assigning dRUs that span a portion of the operating bandwidth that has poor channel quality.

[0036] For purposes of illustration, various embodiments are described herein in the context of wireless networks that are based on IEEE 802.11 standards and using terminology and concepts thereof. Those skilled in the art will appreciate that the embodiments disclosed herein can be modified / adapted for use in other types of wireless networks.

[0037] In the following detailed description, only certain embodiments of the present invention have been shown and described, simply by way of illustration. As those skilled in the art would realize, the described embodiments may be modified in different ways, all without departing from the spirit or scope of the present invention. Accordingly, the drawings and description are to be regarded as illustrative in nature and not restrictive. Like reference numerals designate like elements throughout the specification.

[0038] Figure 1 shows a wireless local area network (WLAN) 100 with a basic service set (BSS) 102 that includes a plurality of wireless devices 104 (sometimes referred to as WLAN devices 104). Each of the wireless devices 104 may include a medium access control (MAC) layer and a physical (PHY) layer according to an IEEE (Institute of Electrical and Electronics Engineers) standard 802.11, including one or more of the amendments (e.g., 802.1 la / b / g / n / p / ac / ax / bd / be). In one embodiment, the MAC layer of a wireless device 104 may initiate transmission of a frame to another wireless device 104 by passing a PHY- TXSTART. request (TXVECTOR) to the PHY layer. The TXVECTOR provides parameters for generating and / or transmitting a corresponding frame. Similarly, a PHY layer of a receiving wireless device may generate an RXVECTOR, which includes parameters of a received frame and is passed to a MAC layer for processing.

[0039] The plurality of wireless devices 104 may include a wireless device 104A that is an access point (sometimes referred to as an AP station or AP STA) and the other wireless devices 104B1-104B4 that are non-AP stations (sometimes referred to as non-AP STAs). Alternatively, all the plurality of wireless devices 104 may be non-AP STAs in an ad-hoc networking environment. In general, the AP STA (e.g., wireless device 104A) and the non-AP STAs (e.g., wireless devices 104B1-104B4) may be collectively referred to as STAs. However, for ease of description, only the non-AP STAs may be referred to as STAs unless the context indicates otherwise. Although shown with four non-AP STAs (e.g., the wireless devices 104B1- 104B4), the WLAN 100 may include any number of non-AP STAs (e.g., one or more wireless devices 104B).

[0040] Figure 2 illustrates a schematic block diagram of a wireless device 104, according to an embodiment. The wireless device 104 may be the wireless device 104A (i.e., the AP of the WLAN 100) or any of the wireless devices 104B1-104B4 in Figure 1. The wireless device 104 includes a baseband processor 210, a radio frequency (RF) transceiver 240, an antenna unit 250, a storage device (e.g., memory device) 232, one or more input interfaces 234, and one or more output interfaces 236. The baseband processor 210, the storage device 232, the input interfaces 234, the output interfaces 236, and the RF transceiver 240 may communicate with each other via a bus 260.

[0041] The baseband processor 210 performs baseband signal processing and includes a MAC processor 212 and a PHY processor 222. The baseband processor 210 may utilize the memory 232, which may include a non-transitory computer / machine readable medium having software (e.g., computer / machine programing instructions) and data stored therein.

[0042] In an embodiment, the MAC processor 212 includes a MAC software processing unit 214 and a MAC hardware processing unit 216. The MAC software processing unit 214 may implement a first plurality of functions of the MAC layer by executing MAC software, which may be included in the software stored in the storage device 232. The MAC hardware processing unit 216 may implement a second plurality of functions of the MAC layer in specialpurpose hardware. However, the MAC processor 212 is not limited thereto. For example, the MAC processor 212 may be configured to perform the first and second plurality of functions entirely in software or entirely in hardware according to an implementation.

[0043] The PHY processor 222 includes a transmitting (TX) signal processing unit (SPU) 224 and a receiving (RX) SPU 226. The PHY processor 222 implements a plurality of functions of the PHY layer. These functions may be performed in software, hardware, or a combination thereof according to an implementation.

[0044] Functions performed by the transmitting SPU 224 may include one or more of Forward Error Correction (FEC) encoding, stream parsing into one or more spatial streams, diversity encoding of the spatial streams into a plurality of space-time streams, spatial mapping of the space-time streams to transmit chains, inverse Fourier Transform (iFT) computation, Cyclic Prefix (CP) insertion to create a Guard Interval (GI), and the like. Functions performed by the receiving SPU 226 may include inverses of the functions performed by the transmitting SPU 224, such as GI removal, Fourier Transform computation, and the like.

[0045] The RF transceiver 240 includes an RF transmitter 242 and an RF receiver 244. The RF transceiver 240 is configured to transmit first information received from the baseband processor 210 to the WLAN 100 (e.g., to another WLAN device 104 of the WLAN 100) and provide second information received from the WLAN 100 (e.g., from another WLAN device 104 of the WLAN 100) to the baseband processor 210.

[0046] 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 a plurality of antennas. In an embodiment, the antennas in the antenna unit 250 may operate as a beam-formed antenna array. In an embodiment, the antennas in the antenna unit 250 may be directional antennas, which may be fixed or steerable.

[0047] The input interfaces 234 receive information from a user, and the output interfaces 236 output information to the user. The input interfaces 234 may include one or more of a keyboard, keypad, mouse, touchscreen, microphone, and the like. The output interfaces 236 may include one or more of a display device, touch screen, speaker, and the like.

[0048] As described herein, many functions of the WLAN device 104 may be implemented in either hardware or software. Which functions are implemented in software and which functions are implemented in hardware will vary according to constraints imposed on a design. The constraints may include one or more of design cost, manufacturing cost, time to market, power consumption, available semiconductor technology, etc.

[0049] As described herein, a wide variety of electronic devices, circuits, firmware, software, and combinations thereof may be used to implement the functions of the components of the WLAN device 104. Furthermore, the WLAN device 104 may include other components, such as application processors, storage interfaces, clock generator circuits, power supply circuits, and the like, which have been omitted in the interest of brevity.

[0050] Figure 3 A illustrates components of a WLAN device 104 configured to transmit data according to an embodiment, including a transmitting (Tx) SPU (TxSP) 324, an RF transmitter 342, and an antenna 352. In an embodiment, the TxSP 324, the RF transmitter 342, and the antenna 352 correspond to the transmitting SPU 224, the RF transmitter 242, and an antenna of the antenna unit 250 of Figure 2, respectively.

[0051] The TxSP 324 includes an encoder 300, an interleaver 302, a mapper 304, an inverse Fourier transformer (IFT) 306, and a guard interval (GI) inserter 308.

[0052] The encoder 300 receives and encodes input data. In an embodiment, the encoder 300 includes a forward error correction (FEC) encoder. The FEC encoder may include a binary convolution code (BCC) encoder followed by a puncturing device. The FEC encoder may include a low-density parity-check (LDPC) encoder.

[0053] The TxSP 324 may further include a scrambler for scrambling the input data before the encoding is performed by the encoder 300 to reduce the probability of long sequences of 0s or Is. When the encoder 300 performs the BCC encoding, the TxSP 324 may further include an encoder parser for demultiplexing the scrambled bits among a plurality of BCC encoders. If LDPC encoding is used in the encoder, the TxSP 324 may not use the encoder parser.

[0054] The interleaver 302 interleaves the bits of each stream output from the encoder 300 to change an order of bits therein. The interleaver 302 may apply the interleaving only when the encoder 300 performs BCC encoding and otherwise may output the stream output from the encoder 300 without changing the order of the bits therein.

[0055] The mapper 304 maps the sequence of bits output from the interleaver 302 to constellation points. If the encoder 300 performed LDPC encoding, the mapper 304 may also perform LDPC tone mapping in addition to constellation mapping.

[0056] When the TxSP 324 performs a MIMO or MU-MIMO transmission, the TxSP 324 may include a plurality of interleavers 302 and a plurality of mappers 304 according to a number of spatial streams (NSS) of the transmission. The TxSP 324 may further include a stream parser for dividing the output of the encoder 300 into blocks and may respectively send the blocks to different interleavers 302 or mappers 304. The TxSP 324 may further include a space-time block code (STBC) encoder for spreading the constellation points from the spatial streams into a number of space-time streams (NSTS) and a spatial mapper for mapping the space-time streams to transmit chains. The spatial mapper may use direct mapping, spatial expansion, or beamforming.

[0057] The IFT 306 converts a block of the constellation points output from the mapper 304 (or, when MIMO or MU-MIMO is performed, the spatial mapper) to a time domain block (i.e., a symbol) by using an inverse discrete Fourier transform (IDFT) or an inverse fast Fourier transform (IFFT). If the STBC encoder and the spatial mapper are used, the IFT 306 may be provided for each transmit chain.

[0058] When the TxSP 324 performs a MIMO or MU-MIMO transmission, the TxSP 324 may insert cyclic shift diversities (CSDs) to prevent unintentional beamforming. The TxSP 324 may perform the insertion of the CSD before or after the IFT 306. The CSD may be specified per transmit chain or may be specified per space-time stream. Alternatively, the CSD may be applied as a part of the spatial mapper.

[0059] When the TxSP 324 performs a MIMO or MU-MIMO transmission, some blocks before the spatial mapper may be provided for each user.

[0060] The GI inserter 308 prepends a GI to each symbol produced by the IFT 306. Each GI may include a Cyclic Prefix (CP) corresponding to a repeated portion of the end of the symbol that the GI precedes. The TxSP 324 may optionally perform windowing to smooth edges of each symbol after inserting the GI.

[0061] The RF transmitter 342 converts the symbols into an RF signal and transmits the RF signal via the antenna 352. When the TxSP 324 performs a MIMO or MU-MIMO transmission, the GI inserter 308 and the RF transmitter 342 may be provided for each transmit chain.

[0062] Figure 3B illustrates components of a WLAN device 104 configured to receive data according to an embodiment, including a Receiver (Rx) SPU (RxSP) 326, an RF receiver 344, and an antenna 354. In an embodiment, the RxSP 326, RF receiver 344, and antenna 354 may correspond to the receiving SPU 226, the RF receiver 244, and an antenna of the antenna unit 250 of Figure 2, respectively.

[0063] The RxSP 326 includes a GI remover 318, a Fourier transformer (FT) 316, a demapper 314, a deinterleaver 312, and a decoder 310.

[0064] The RF receiver 344 receives an RF signal via the antenna 354 and converts the RF signal into symbols. The GI remover 318 removes the GI from each of the symbols. When the received transmission is a MIMO or MU-MIMO transmission, the RF receiver 344 and the GI remover 318 may be provided for each receive chain.

[0065] The FT 316 converts each symbol (that is, each time domain block) into a frequency domain block of constellation points by using a discrete Fourier transform (DFT) or a fast Fourier transform (FFT). The FT 316 may be provided for each receive chain.

[0066] When the received transmission is the MIMO or MU-MIMO transmission, the RxSP 326 may include a spatial demapper for converting the respective outputs of the FTs 316 of the receiver chains to constellation points of a plurality of space-time streams, and an STBC decoder for despreading the constellation points from the space-time streams into one or more spatial streams.

[0067] The demapper 314 demaps the constellation points output from the FT 316 or the STBC decoder to bit streams. If the received transmission was encoded using LDPC encoding, the demapper 314 may further perform LDPC tone demapping before performing the constellation demapping.

[0068] The deinterleaver 312 deinterleaves the bits of each stream output from the demapper 314. The deinterleaver 312 may perform the deinterleaving only when the received transmission was encoded using BCC encoding, and otherwise may output the stream output by the demapper 314 without performing deinterleaving.

[0069] When the received transmission is the MIMO or MU-MIMO transmission, the RxSP 326 may use a plurality of demappers 314 and a plurality of deinterleavers 312 corresponding to the number of spatial streams of the transmission. In this case, the RxSP 326 may further include a stream deparser for combining the streams output from the deinterleavers 312.

[0070] The decoder 310 decodes the streams output from the deinterleaver 312 or the stream deparser. In an embodiment, the decoder 310 includes an FEC decoder. The FEC decoder may include a BCC decoder or an LDPC decoder.

[0071] The RxSP 326 may further include a descrambler for descrambling the decoded data. When the decoder 310 performs BCC decoding, the RxSP 326 may further include an encoder deparser for multiplexing the data decoded by a plurality of BCC decoders. When the decoder 310 performs the LDPC decoding, the RxSP 326 may not use the encoder deparser.

[0072] Before making a transmission, wireless devices such as wireless device 104 will assess the availability of the wireless medium using Clear Channel Assessment (CCA). If the medium is occupied, CCA may determine that it is busy, while if the medium is available, CCA determines that it is idle.

[0073] The PHY entity for IEEE 802.11 is based on Orthogonal Frequency Division Multiplexing (OFDM) or Orthogonal Frequency Division Multiple Access (OFDMA). In either OFDM or OFDMA Physical (PHY) layers, a STA (e.g., a wireless device 104) is capable of transmitting and receiving Physical Layer (PHY) Protocol Data Units (PPDUs) (also referred to as PLCP (Physical Layer Convergence Procedure) Protocol Data Units) that are compliant with the mandatory PHY specifications. A PHY specification defines a set of Modulation and Coding Schemes (MCS) and a maximum number of spatial streams. Some PHY entities define downlink (DL) and uplink (UL) Multi-User (MU) transmissions having a maximum number of space-time streams (STS) per user and employing up to a predetermined total number of STSs. A PHY entity may provide support for 10 Megahertz (MHz), 20 MHz, 40 MHz, 80 MHz, 160 MHz, 240 MHz, and 320 MHz contiguous channel widths and support for an 80+80, 80+160 MHz, and 160+160 MHz non-contiguous channel width. Each channel includes a plurality of subcarriers, which may also be referred to as tones. A PHY entity may define signaling fields denoted as Legacy Signal (L-SIG), Signal A (SIG-A), and Signal B (SIG-B), and the like within a PPDU by which some necessary information about PHY Service Data Unit (PSDU) attributes are communicated. The descriptions below, for sake of completeness and brevity, refer to OFDM-based 802.11 technology. Unless otherwise indicated, a station refers to a non-AP STA.

[0074] Figure 4 illustrates Inter-Frame Space (IFS) relationships. In particular, Figure 4 illustrates a Short IFS (SIFS), a Point Coordination Function (PCF) IFS (PIFS), a Distributed Coordination Function (DCF) IFS (DIFS), and an Arbitration IFSs corresponding to an Access Category (AC) ‘i’ (AIFS[i]). Figure 4 also illustrates a slot time and a data frame is used for transmission of data forwarded to a higher layer. As shown, a WLAN device 104 transmits the data frame after performing backoff if a DIFS has elapsed during which the medium has been idle.

[0075] A management frame may be used for exchanging management information, which is not forwarded to the higher layer. Subtype frames of the management frame include a beacon frame, an association request / response frame, a probe request / response frame, and an authentication request / response frame.

[0076] A control frame may be used for controlling access to the medium. Subtype frames of the control frame include a request to send (RTS) frame, a clear to send (CTS) frame, and an acknowledgement (ACK) frame.

[0077] When the control frame is not a response frame of another frame, the WLAN device 104 transmits the control frame after performing backoff if a DIFS has elapsed during which the medium has been idle. When the control frame is the response frame of another frame, the WLAN device 104 transmits the control frame after a SIFS has elapsed without performing backoff or checking whether the medium is idle.

[0078] A WLAN device 104 that supports Quality of Service (QoS) functionality (that is, a QoS STA) may transmit the frame after performing backoff if an AIFS for an associated access category (AC) (i.e., AIFS[AC]) has elapsed. When transmitted by the QoS STA, any of the data frame, the management frame, and the control frame, which is not the response frame, may use the AIFS [AC] of the AC of the transmitted frame.

[0079] A WLAN device 104 may perform a backoff procedure when the WLAN device 104 that is ready to transfer a frame finds the medium busy. The backoff procedure includes determining a random backoff time composed of N backoff slots, where each backoff slot has a duration equal to a slot time and N being an integer number greater than or equal to zero. The backoff time may be determined according to a length of a Contention Window (CW). In an embodiment, the backoff time may be determined according to an AC of the frame. All backoff slots occur following a DIFS or Extended IFS (EIFS) period during which the medium is determined to be idle for the duration of the period.

[0080] When the WLAN device 104 detects no medium activity for the duration of a particular backoff slot, the backoff procedure shall decrement the backoff time by the slot time. When the WLAN device 104 determines that the medium is busy during a backoff slot, the backoff procedure is suspended until the medium is again determined to be idle for the duration of a DIFS or EIFS period. The WLAN device 104 may perform transmission or retransmission of the frame when the backoff timer reaches zero.

[0081] The backoff procedure operates so that when multiple WLAN devices 104 are deferring and execute the backoff procedure, each WLAN device 104 may select a backoff time using a random function and the WLAN device 104 that selects the smallest backoff time may win the contention, reducing the probability of a collision.

[0082] Figure 5 illustrates a Carrier Sense Multiple Access / Collision Avoidance (CSMA / CA) based frame transmission procedure for avoiding collision between frames in a channel according to an embodiment. Figure 5 shows a first station STA1 transmitting data, a secondstation STA2 receiving the data, and a third station STA3 that may be located in an area where a frame transmitted from the STA1 can be received, a frame transmitted from the second station STA2 can be received, or both can be received. The stations STA1, STA2, and STA3 may be WLAN devices 104 of Figure 1.

[0083] The station STA1 may determine whether the channel is busy by carrier sensing. The station STA1 may determine channel occupation / status based on an energy level in the channel or an autocorrelation of signals in the channel, or may determine the channel occupation by using a network allocation vector (NAV) timer.

[0084] After determining that the channel is not used by other devices (that is, that the channel is IDLE) during a DIFS (and performing backoff if required), the station STA1 may transmit a Request-To-Send (RTS) frame to the station STA2. Upon receiving the RTS frame, after a SIFS the station STA2 may transmit a Clear-To-Send (CTS) frame as a response to the RTS frame. If Dual-CTS is enabled and the station STA2 is an AP, the AP may send two CTS frames in response to the RTS frame (e.g., a first CTS frame in a non-High Throughput format and a second CTS frame in the HT format).

[0085] When the station STA3 receives the RTS frame, it may set a NAV timer of the station STA3 for a transmission duration of subsequently transmitted frames (for example, a duration of SIFS + CTS frame duration + SIFS + data frame duration + SIFS + ACK frame duration) using duration information included in the RTS frame. When the station STA3 receives the CTS frame, it may set the NAV timer of the station STA3 for a transmission duration of subsequently transmitted frames using duration information included in the CTS frame. Upon receiving a new frame before the NAV timer expires, the station STA3 may update the NAV timer of the station STA3 by using duration information included in the new frame. The station STA3 does not attempt to access the channel until the NAV timer expires.

[0086] When the station STA1 receives the CTS frame from the station STA2, it may transmit a data frame to the station STA2 after a SIFS period elapses from a time when the CTS frame has been completely received. Upon successfully receiving the data frame, the station STA2 may transmit an ACK frame as a response to the data frame after a SIFS period elapses.

[0087] When the NAV timer expires, the third station STA3 may determine whether the channel is busy using the carrier sensing. Upon determining that the channel is not used by other devices during a DIFS period after the NAV timer has expired, the station STA3 may attempt to access the channel after a contention window elapses according to a backoff process.

[0088] When Dual-CTS is enabled, a station that has obtained a transmission opportunity (TXOP) and that has no data to transmit may transmit a CF-End frame to cut short the TXOP.An AP receiving a CF-End frame having a Basic Service Set Identifier (BSSID) of the AP as a destination address may respond by transmitting two more CF-End frames: a first CF-End frame using Space Time Block Coding (STBC) and a second CF-End frame using non-STBC. A station receiving a CF-End frame resets its NAV timer to 0 at the end of the PPDU containing the CF-End frame. Figure 5 shows the station STA2 transmitting an ACK frame to acknowledge the successful reception of a frame by the recipient.

[0089] The IEEE 802.1 Ibn (Ultra High Reliability, UHR) working group has been established to address the growing demand for higher peak throughput and reliability in Wi-Fi. As shown in Figure 6, the peak PHY rate has significantly increased from IEEE 802.1 lb to IEEE 802.1 Ibe (Wi-Fi 7), with the latter focusing on further improving peak throughput. The UHR study group aims to enhance the tail of the latency distribution and jitter to support applications that require low latency, such as video-over- WLAN, gaming, AR, and VR. It is noted that various characteristics of UHR (e.g., max PHY rate, PHY rate enhancement, bandwidth / number of spatial streams, and operating bands) are still to be determined.

[0090] The focus of IEEE 802.1 Ibe is primarily on WLAN indoor and outdoor operation with stationary and pedestrian speeds in the 2.4, 5, and 6 GHz frequency bands. In addition to peak PHY rate, different candidate features are under discussion. These candidate features include (1) a 320MHz bandwidth and a more efficient utilization of a non-contiguous spectrum, (2) multi -band / multi-channel aggregation and operation, (3) 16 spatial streams and Multiple Input Multiple Output (MIMO) protocol enhancements, (4) multi-Access Point (AP) Coordination (e.g., coordinated and joint transmission), (5) an enhanced link adaptation and retransmission protocol (e.g., Hybrid Automatic Repeat Request (HARQ)), and (6) adaptation to regulatory rules specific to a 6 GHz spectrum.

[0091] The focus of IEEE 802.1 Ibn (UHR) is still under discussion, with candidate features including MLO enhancements (e.g., in terms of increased throughput / reliability and decreased latency), latency and reliability improvements (e.g., multi-AP coordination to support low latency traffic), bandwidth expansion (e.g., to 240, 480, 640 MHz), aggregated PPDU (A- PPDU), enhanced multi-link single-radio (eMLSR) extensions to AP, roaming improvements, and power-saving schemes for prolonging battery life.

[0092] Some features, such as increasing the bandwidth and the number of spatial streams, are solutions that have been proven to be effective in previous projects focused on increasing link throughput and on which feasibility demonstration is achievable.

[0093] With respect to operational bands (e.g., 2.4 / 5 / 6 GHz) for IEEE 802.1 Ibe, more than 1 GHz of additional unlicensed spectrum is likely to be available because the 6 GHzband (5.925- 7.125 GHz) is being considered for unlicensed use. This would allow APs and STAs to become tri -band devices. Larger than 160MHz data transmissions (e.g., 320 MHz or 640 MHz) could be considered to increase the maximum PHY rate. For example, 320 MHz or 160+160MHz data could be transmitted in the 6 GHz band. For example, 160+160 MHz data could be transmitted across the 5 and 6 GHz bands.

[0094] In the process of wireless communication, a transmitting station (STA) creates a Physical Layer Protocol Data Unit (PPDU) frame and sends it to a receiving STA. The receiving STA then receives, detects, and processes the PPDU.

[0095] The Extremely High Throughput (EHT) PPDU frame encompasses several components. It includes a legacy part, which comprises fields such as the Legacy Short Training Field (L-STF), Legacy Long Training Field (L-LTF), Legacy Signal Field (L-SIG), and Repeated Legacy Signal Field (RL-SIG). These fields are used to maintain compatibility with older Wi-Fi standards.

[0096] In addition to the legacy part, the EHT PPDU frame also contains the Universal Signal Field (U-SIG), EHT Signal Field (EHT-SIG), EHT Short Training Field (EHT-STF), and EHT Long Training Field (EHT-LTF). These fields are specific to the EHT standard and are used for various purposes, such as signaling, synchronization, and channel estimation.

[0097] Figure 7 provides a more detailed description of each field in the EHT PPDU frame, including their purposes and characteristics.

[0098] Regarding the Ultra High Reliability (UHR) PPDU, its frame structure is currently undefined and will be determined through further discussions within the relevant working group or study group. This indicates that the specifics of the UHR PPDU are still under development and will be finalized based on the outcomes of future deliberations.

[0099] The distributed nature of channel access networks, such as IEEE 802.11 WLANs, makes the carrier sense mechanism useful for ensuring collision-free operation. Each station (STA) uses its physical carrier sense to detect transmissions from other STAs. However, in certain situations, it may not be possible for a STA to detect every transmission. For instance, when one STA is located far away from another STA, it might perceive the medium as idle and start transmitting a frame, leading to collisions. To mitigate this hidden node problem, the network allocation vector (NAV) has been introduced.

[0100] As the IEEE 802.11 standard continues to evolve, it now includes scenarios where multiple users can simultaneously transmit or receive data within a basic service set (BSS), such as uplink (UL) and downlink (DL) multi-user (MU) transmissions in a cascaded manner. In these cases, the existing carrier sense and NAV mechanisms may not be sufficient, andmodifications or newly defined mechanisms may be required to facilitate efficient and collision- free operation.

[0101] For the purpose of this disclosure, MU transmission refers to situations where multiple frames are transmitted to or from multiple STAs simultaneously using different resources. Examples of these resources include different frequency resources in Orthogonal Frequency Division Multiple Access (OFDMA) transmission and different spatial streams in Multi-User Multiple Input Multiple Output (MU-MIMO) transmission. Consequently, downlink OFDMA (DL-OFDMA), downlink MU-MIMO (DL-MU-MIMO), uplink OFDMA (UL- OFDMA), uplink MU-MIMO (UL-MU-MIMO), and OFDMA with MU-MIMO are all considered examples of MU transmission.

[0102] Figure 8 illustrates an example of multi-user (MU) transmission in Orthogonal Frequency-Division Multiple Access (OFDMA), in accordance with some embodiments of the present disclosure.

[0103] In the IEEE 802.1 lax and 802.1 Ibe specifications, the trigger frame plays a useful role in facilitating uplink multi-user (MU) transmissions. The purpose of the trigger frame is to allocate resources and solicit one or more Trigger-based (TB) Physical Layer Protocol Data Unit (PPDU) transmissions from the associated stations (STAs).

[0104] The trigger frame contains information required by the responding STAs to send their Uplink TB PPDUs. This information includes the Trigger type, which specifies the type of TB PPDU expected, and the Uplink Length (UL Length), which indicates the duration of the uplink transmission.

[0105] Figure 9 illustrates an example scenario where an access point (AP) operating in an 80MHz bandwidth environment sends a Trigger frame to multiple associated STAs. Upon receiving the Trigger frame, the STAs respond by sending their respective Uplink Orthogonal Frequency Division Multiple Access (UL OFDMA) TB PPDUs, utilizing the allocated resources within the specified 80 MHz bandwidth.

[0106] After successfully receiving the UL OFDMA TB PPDUs, the AP acknowledges the STAs by sending an acknowledgement frame. This acknowledgement can be in the form of an 80MHz width multi-STA Block Acknowledgement (Block Ack) or a Block Acknowledgement with a Direct Feedback (DF) OFDMA method. The multi-STA Block Ack allows the AP to acknowledge multiple STAs simultaneously, while the Block Ack with DF OFDMA enables the AP to provide feedback to the STAs using the same OFDMA technique employed in the uplink transmission.

[0107] The trigger frame is a useful component in enabling efficient uplink MU transmissions in IEEE 802.1 lax and 802.1 Ibe networks, by allocating resources and coordinating the uplink transmissions from multiple STAs within the same bandwidth.

[0108] Wireless network systems can rely on retransmission of media access control (MAC) protocol data units (MPDUs) when the transmitter (TX) does not receive an acknowledgement from the receiver (RX) or MPDUs are not successfully decoded by the receiver. Using an automatic repeat request (ARQ) approach, the receiver discards the last failed MPDU before receiving the newly retransmitted MPDU. With requirements of enhanced reliability and reduced latency, the wireless network system can evolve toward a hybrid ARQ (HARQ) approach.

[0109] There are two methods of HARQ processing. In a first type of HARQ scheme, also referred to as chase combining (CC) HARQ (CC-HARQ) scheme, signals to be retransmitted are the same as the signals that previously failed because all subpackets to be retransmitted use the same puncturing pattern. The puncturing is needed to remove some of the parity bits after encoding using an error-correction code. The reason why the same puncturing pattern is used with CC-HARQ is to generate a coded data sequence with forward error correction (FEC) and to make the receiver use a maximum-ratio combining (MRC) to combine the received, retransmitted bits with the same bits from the previous transmission. For example, information sequences are transmitted in packets with a fixed length. At a receiver, error correction and detection are carried out over the whole packet. However, the ARQ scheme may be inefficient in the presence of burst errors. To solve this more efficiently, subpackets are used. In subpacket transmissions, only those subpackets that include errors need to be retransmitted.

[0110] Since the receiver uses both the current and the previously received subpackets for decoding data, the error probability in decoding decreases as the number of used subpackets increases. The decoding process passes a cyclic redundancy check (CRC) and ends when the entire packet is decoded without error or the maximum number of subpackets is reached. In particular, this scheme operates on a stop-and-wait protocol such that if the receiver can decode the packet, it sends an acknowledgement (ACK) to the transmitter. When the transmitter receives an ACK successfully, it terminates the HARQ transmission of the packet. If the receiver cannot decode the packet, it sends a negative acknowledgement (NAK) to the transmitter and the transmitter performs the retransmission process.

[0111] In a second type of HARQ scheme, also referred to as an incremental redundancy (IR) HARQ (IR-HARQ) scheme, different puncturing patterns are used for each subpacket such that the signal changes for each retransmitted subpacket in comparison to the originally transmittedsubpacket. IR-HARQ alternatively uses two puncturing patterns for odd numbered and even numbered transmissions, respectively. The redundancy scheme of IR-HARQ improves the log likelihood ratio (LLR) of parity bit(s) in order to combine information sent across different transmissions due to requests and lowers the code rate as the additional subpacket is used. This results in a lower error rate of the subpacket in comparison to CC-HARQ. The puncturing pattern used in IR-HARQ is indicated by a subpacket identity (SPID) indication. The SPID of the first subpacket may always be set to 0 and all the systematic bits and the punctured parity bits are transmitted in the first subpacket. Self-decoding is possible when the receiving signal- to-noise ratio (SNR) environment is good (i.e., a high SNR). In some embodiments, subpackets with corresponding SPIDs to be transmitted are in increasing order of SPID but can be exchanged / switched except for the first SPID.

[0112] AP coordination has been considered as a potential technology to improve WLAN system throughput in the IEEE 802.1 Ibe standard and is still being discussed in the IEEE 802.1 Ibn (UHR) standard. To support various AP coordination schemes, such as coordinated beamforming, OFDMA, TDMA, spatial reuse, and joint transmission, a predefined mechanism for APs is necessary.

[0113] In the context of coordinated TDMA (C-TDMA), the AP that obtains a transmit opportunity (TXOP) is referred to as the sharing AP. This AP initiates the AP coordination schemes to determine the AP candidate set by sending a frame, such as a Beacon frame or probe response frame, which includes information about the AP coordination scheme capabilities. The AP that participates in the AP coordination schemes after receiving the frame from the sharing AP is called the shared AP. The sharing AP is also known as the master AP or coordinating AP, while the shared AP is referred to as the slave AP or coordinated AP.

[0114] The operation of various AP coordination schemes has been discussed in the IEEE 802.1 Ibe and UHR standards:

[0115] Coordinated Beamforming (C-BF): Multiple APs transmit on the same frequency resource by coordinating and forming spatial nulls, allowing for simultaneous transmission from multiple APs.

[0116] Coordinated OFDMA (C-OFDMA): APs transmit on orthogonal frequency resources by coordinating and splitting the spectrum, enabling more efficient spectrum utilization.

[0117] Joint Transmission (JTX): Multiple APs transmit jointly to a given user simultaneously by sharing data between the APs.

[0118] Coordinated Spatial Reuse (C-SR): Multiple APs or STAs adjust their transmit power to reduce interference between APs.

[0119] By implementing these AP coordination schemes, WLAN systems can improve their overall throughput and efficiency by leveraging the cooperation between multiple APs.

[0120] Distributed tone resource unit (dRU) is a physical (PHY) layer feature that can help improve spectral efficiency. The use of dRUs may help with overcoming the power spectral density (PSD) limitation. Various power modes are defined in 6 GHz bands such as standard power (SP) mode, very low power (VLP) mode, and low power indoor (LPI) mode. The PSD limitation is stringent especially in VLP mode and LPI mode in 6 GHz bands and especially for non-AP STAs. For example, the PSD limitation of a non-AP STA in LPI mode is -1 dBM / MHz. As a result, using many RU tones in a limited bandwidth can decrease transmit power due to the stringent PSD limitation.

[0121] The use of dRU can overcome this limitation by distributing tones within a distribution bandwidth.

[0122] Figure 10 is a diagram showing a regular resource unit assignment in a 80 MHz bandwidth, according to some embodiments.

[0123] The diagram shows a regular (non-distributed) tone resource unit (rRU) tone plan for a 80 MHz bandwidth. As shown in the diagram, the rRU tone plan may specify one 996 RU, two 484-tone RUs, four 242-tone RUs, eight 106-tone RUs, sixteen 52-tone RUs, and thirty- six 26-tone RUs.

[0124] If it is assumed that a basic service set (BSS) includes one access point (AP) and two non-AP stations (STAs) that operate in a 80 MHz bandwidth (i.e., the operating bandwidth is 80 MHz), the AP may assign RUs to the two non-AP STAs according to the rRU tone plan for the 80 MHz bandwidth. For example, as shown in the diagram, the AP may assign the first 484- tone RU to the first non-AP STA (“STA1”) and assign the second 484-tone RU to the second non-AP STA (“STA2”) using orthogonal frequency division multiple access (OFDMA).

[0125] Transmitting in dRUs instead of rRUs may allow for significantly boosting the transmission power.

[0126] Figure 11 is a diagram showing a distributed tone resource unit assignment in a 80 MHz bandwidth, according to some embodiments.

[0127] The diagram shows a dRU tone plan for a 80 MHz distribution bandwidth. As shown in the diagram, the dRU tone plan may specify two 484-tone dRUs (484 dRU-1 and 484 dRU- 2). Each 484-tone dRU may include tones that are distributed across the 80 MHz distribution bandwidth. The dRU tone plan may also specify dRUs with other sizes (e.g., 242-tone dRUs, 106-tone dRUs, etc.). Hatching is used in the diagram to represent that the resource units are composed of distributed tones (i.e., the resource units are dRUs).

[0128] If it is again assumed again that a BSS includes one AP and two non-AP STAs that operate in a 80 MHz bandwidth, the AP may assign dRUs to the two non-AP STAs according to the dRU tone plan for the 80 MHz bandwidth. For example, the AP may assign the first 484- tone dRU (484-tone dRU-1) to the first non-AP STA (“STA1”) and assign the second 484-tone dRU (484-tone dRU-2) to the second non-AP STA (“STA2”).

[0129] When comparing the rRU scheme with the dRU scheme in the example RU assignment examples mentioned above, both schemes assign the same size RU to the two non- AP STAs (e.g., 484-tone RU) but the same size RU spans a wider bandwidth in the dRU scheme (e.g., the 484-tone RU in the rRU scheme spans a 40 MHz bandwidth but the 484-tone dRU in the dRU scheme spans a 80 MHz bandwidth). As such, using the dRU scheme lowers the number of tones included in 1 MHz, allowing for higher transmit power.

[0130] A dRU scheme (e.g., as shown in Figure 11) may coexist with rRUs (e.g., rRUs or multiple rRUs shown in Figure 10). For example, if it is assumed that there is an AP and three non-AP STAs (non-AP STA1, non-AP STA2, and non-AP STA33) that operate in a 160 MHz bandwidth (the operating bandwidth is 160 MHz), the AP may transmit a trigger frame to solicit an uplink trigger-based PPDU from the non-AP STAs. The AP may include an indication of a resource unit assignment in the trigger frame. As an example, the resource unit assignment may be as follows:

[0131] 1) Assign a 996-tone rRU (e.g., the 996-tone rRU specified by the rRU tone plan shown in Figure 10) to non-AP STA1.

[0132] 2) Assign 484-tone dRUs (e.g., the 484-tone dRUs specified by the dRU tone plan shown in Figure 11) to non-AP STA1 and non-AP STA2, respectively.

[0133] Thus, the AP may decide to assign rRUs and / or dRUs to non-AP STAs (a so-called “hybrid” assignment of RUs) when it solicits an uplink trigger-based PPDU from the non-AP STAs.

[0134] It has been recognized by the present disclosure that when the AP solicits uplink transmission from non-AP STAs in dRUs, it should check the following conditions to assign dRUs efficiently. First, the AP should check the channel condition of the of the operating bandwidth, as this may affect whether it is possible to use a dRU that spans the entire operating bandwidth or not. For example, if the AP operates in a 80 MHz bandwidth, the AP should check the channel condition of the 80 MHz bandwidth. If a portion of the 80 MHz bandwidth has poor channel quality at a non-AP STA (e.g., because a 20 MHz portion of the 80 MHz bandwidth suffers from interference), then it might not be possible to use a dRU that spans the entire 80 MHz bandwidth. If the AP assigns a dRU that spans the entire 80 MHz bandwidth to the non-AP STA, the non-AP STA may not be able to use the assigned dRU, resulting in the waste of frequency resources. Second, the AP should check which non-AP STAs have buffered data to transmit to avoid assigning dRUs to non-AP STAs that do not have buffered data to transmit. Assigning dRUs to non-AP STAs that do not have buffered data to transmit is a waste of frequency resources and thus should be avoided when possible.

[0135] The present disclosure introduces a frame exchange sequence that allows the AP to determine which (non-AP) STAs have buffered data to transmit and to determine the channel condition of an operating bandwidth. The AP may use the information obtained from the frame exchange sequence to assign dRUs to STAs in an efficient manner and thus improve spectral efficiency.

[0136] The AP may use an enhanced trigger frame to solicit information from non-AP STAs regarding whether they have buffered data to transmit or not. A non-AP STA that receives the enhanced trigger frame may transmit an enhanced feedback report frame to the AP as a response to the enhanced trigger frame. The non-AP STA may transmit a preamble field of the enhanced feedback report frame in a dRU. The preamble field may include an indication of whether the non-AP STA has buffered data to transmit or not. The AP may use the enhanced feedback report frame it receives from the non-AP STAs to determine which non-AP STAs have buffered data to transmit and also to determine the channel condition at the non-AP STAs (e.g., a failure to receive the enhanced feedback report frame in a portion of the bandwidth may be indicative of poor channel condition at a non-AP STA) . The AP may use this information to assign dRUs to STAs in an efficient manner.

[0137] The AP may perform operations in three phases: phase 1, phase 2, and phase 3, which are described in additional detail herein below.Phase 1

[0138] Before transmitting the enhanced trigger frame, the AP may recognize various information based on exchanging frames (e.g., beacon frame, probe request / response frame, etc.) with non-AP STAs. The information that the AP may recognize may be referred to as conditions in this disclosure. Three conditions are described in further detail herein below.Phase 1 Condition 1

[0139] The AP may recognize the operating bandwidth of non-AP STAs that are capable of transmitting in dRUs. For example, when the AP configures a BSS with non-AP STA1 to non- AP STA10, the AP and the non-AP STAs may recognize the operating bandwidth. This meansthat the AP may recognize the operating bandwidths of all non-AP STAs that are associated with the AP. For example, the AP may recognize the following information:AP operating bandwidth (OPBW): 160MHzNon-AP STA1 OPBW : 40 MHz Non-AP STA2 OPBW : 80 MHzNon-AP STA10 OPBW : 80 MHzPhase 1 Condition 2

[0140] The AP may recognize the association IDs (AIDs) of non-AP STAs. For example, when the AP configures the BSS with non-AP STA1 to non-AP STA10, the AP may assign AIDs to the non-AP STAs. The AP may recognize the AIDs assigned to the non-AP STAs. Also, each non-AP STA may recognize the AID assigned to itself. As an example, the AP may assign AIDs to the non-AP STAs as follows: Non-AP STA1 AID : 1000Non-AP STA2 AID: 2000Non-AP STA10 AID : 2009

[0141] In an embodiment, when the AP assigns AIDs to the non-AP STAs, it assigns AIDs according to the operating bandwidths of the non-AP STAs. For example, the AP may incrementally assign AID numbers starting with AID 1000 to non-AP STAs that have a 40 MHz operating bandwidth (e.g., assign AIDs 1000, 1000+1, 1000+2, and so on). Also, the AP may incrementally assign AID numbers starting with AID 2000 to non-AP STAs that have a 80 MHz operating bandwidth (e.g., assign AIDs 2000, 2000+1, 2000+2, and so on). That is, the starting AID number for non-AP STAs that have a 40 MHz operating bandwidth may be 1000 and the starting AID number for non-AP STAs that have a 40 MHz operating bandwidth may be 2000. Thus, the operating bandwidth of a non-AP STA may be easily recognized based on the AID assigned to the STA (e.g., it can be recognized that a STA that is assigned an AID in the range 1000-1999 has a 40 MHz operating bandwidth and a STA that is assigned an AID in the range 2000-2999 has a 80 MHz operating bandwidth).Phase 1 Condition 3

[0142] The AP and non-AP STAs may recognize the design of the dRU tone plan (e.g., the dRU tone plan shown in Figure 11). The dRU tone plan may be for a 20 MHz distributionbandwidth, 40MHz distribution bandwidth, or 80MHz distribution bandwidth (it should be appreciated, however, that other distribution bandwidths are possible).

[0143] As an example, the design of a 20 MHz dRU tone plan may be as follows (in terms of the number of dRUs):20 MHz dRU tone plan (A > B > C):Number of 26-tone dRUs = A (e.g., 26-tone dRU-1, . . ., 26-tone dRU-A) Number of 52-tone dRUs = B (e.g., 52-tone dRU-1, . . ., 52-tone dRU-B) Number of total 106-tone dRUs = C (e.g., 106-tone dRU-1, . . ., 106-tone dRU-C)

[0144] As another example, the design of a 40 MHz dRU tone plan may be as follows: 40 MHz d RU tone plan (D > E > F > G):Number of 26-tone dRUs = D (e.g., 26-tone dRU-1, . . ., 26-tone dRU-D) Number of 52-tone dRUs = E (e.g., 52-tone dRU-1, . . ., 52-tone dRU-E) Number of 106-tone dRUs = F (e.g., 106-tone dRU-1, . . ., 106-tone dRU-F) Number of 242-tone dRUs = G (e.g., 242-tone dRU-1, . . ., 242-tone dRU-G)

[0145] As another example, the design of a 80 MHz dRU tone plan may be as follows: 80 MHz dRU tone plan (H > I > J > K):Number of 52-tone dRUs = H (e.g., 52-tone dRU-1, . . ., 52-tone dRU-H)Number of 106-tone dRUs = I (e.g., 106-tone dRU-1, . . ., 106-tone dRU-I)Number of 242-tone dRUs = J (e.g., 242-tone dRU-1, . . ., 242-tone dRU-J) Number of 484-tone dRUs = K (e.g., 484-tone dRU-1, . . ., 484-tone dRU-K)

[0146] Figure 12 is a diagram showing a 80 MHz dRU tone plan that specifies four 242-tone dRUs, according to some embodiments.

[0147] The diagram shows a dRU tone plan for a 80 MHz distribution bandwidth. As shown in the diagram, the dRU tone plan may specify four 242-tone dRUs (242-tone dRU-1, 242-tone dRU-2, 242-tone dRU-3, and 242-tone dRU-4). Each 242-tone dRU may include tones that are distributed across the 80 MHz bandwidth. The AP and non-AP STAs may recognize the design of this dRU tone plan.Phase 2Phase 2 Condition 4

[0148] Based on one or more of phase 1 conditions 1-3, the AP may decide the dRU-based PPDU bandwidth (e.g., 20 MHz, 40 MHz, 80 MHz, etc.). In an embodiment, the AP decides the dRU-based PPDU bandwidth to be the bandwidth that covers the most number of non-AP STAs. For example, assume there are X number of non-AP STAs that have a 20 MHz operatingbandwidth and that the number of available 26-tone dRUs is A, B, and C. In this case, if X is greater than A / B / C, this means that the AP cannot accommodate all X non-AP STAs so the AP may consider using a 40 MHz or 80 MHz bandwidth instead. After the AP decides the PPDU bandwidth, it may determine the non-AP STAs that have an operating bandwidth that is the same width as the PPDU bandwidth.

[0149] For example, if the AP decides that the PPDU bandwidth will be 80MHz, the AP may determine the non-AP STAs that have an operating bandwidth of 80 MHz. The 80 MHz dRU- based PPDU may follow the 80 MHz dRU tone plan (e.g., the 80 MHz dRU tone plan recognized in phase 1 condition 3).

[0150] The AP may determine the dRU size based on the number of non-AP STAs that have the operating bandwidth. According to the 80 MHz dRU tone plan (e.g., the dRU tone plan shown in Figure 11), the maximum number of non-AP STAs that can transmit simultaneously is H. Various cases are described below assuming that the operating bandwidth is 80 MHz.

[0151] Case l is a case where the number of non-AP STAs is P, where P is greater than H (P > H). In this case, the AP may choose H non-AP STAs (e.g., according to some rules) and assign 52-tone dRUs to the H non-AP STAs. The AP may assign the 52-tone dRUs to the H non-AP STAs sequentially. For example, non-AP STA with AID 1000 may be assigned 52-tone dRU-1 and non-AP STA with AID 1000+H may be assigned 52-tone dRU-H. The AP may store the AID and assigned dRU number of each non-AP STA.

[0152] Case 2 is a case where the number of non-AP STAs is P, where P is greater than I but less than or equal to H (I < P <= H). In this case, the AP may assign 52-tone dRUs to the P non- AP STAs. The AP may assign the 52-tone dRUs to the P non-AP STAs sequentially. For example, non-AP STA with AID 1000 may be assigned 52-tone dRU-1 and non-AP STA with AID 1000+P may be assigned 52-tone dRU-P. The AP may store the AID and assigned dRU number of each non-AP STA.

[0153] Case 3 is a case where the number of non-AP STAs is P, where P is greater than J but less than or equal to I (J < P <= I). In this case, the AP may assign 106-tone dRUs to the P non- AP STAs. The AP may assign the 106-tone dRUs to the P non-AP STAs sequentially. For example, non-AP STA with AID 1000 may be assigned 106-tone dRU-1 and non-AP STA with AID 1000+P may be assigned 106-tone dRU-P. The AP may store the AID and assigned dRU number of each non-AP STA.

[0154] Case 4 is a case where the number of non-AP STAs is P, where P is greater than K but less than or equal to J (K < P <= J). In this case, the AP may assign 242-tone dRUs to the P non-AP STAs. The AP may assign the 242-tone dRUs to the P non-AP STAs sequentially. Forexample, non-AP STA with AID 1000 may be assigned 242-tone dRU-1 and non-AP STA with AID 1000+P may be assigned 242-tone dRU-P. The AP may store the AID and assigned dRU number of each non-AP STA.

[0155] Case 5 is a case where the number of non-AP STAs is P, where P is greater than zero but less than or equal to K (0 < P <= K). In this case, the AP may assign 484-tone dRUs to the P non-AP STAs. The AP may assign the 484-tone dRUs to the P non-AP STAs sequentially. For example, non-AP STA with AID 1000 may be assigned 484-tone dRU-1 and non-AP STA with AID 1000+P may be assigned 484-tone dRU-P. The AP may store the AID and assigned dRU number of each non-AP STA.

[0156] Figure 13 is a diagram showing an assignment of dRUs to four non-AP STAs in accordance with a 80 MHz dRU tone plan, according to some embodiments.

[0157] In the example shown in the diagram, it is assumed that that there are four non-AP STAs (non-AP STA1, non-AP STA2, non-AP STA3, and non-AP STA4) and that non-AP STA1 has an AID of 1000, non-AP STA2 has an AID of 1001, non-AP STA3 has an AID of 1002, and non-AP STA4 has an AID of 1003. Since there are four non-AP STAs (P=4), the d-RU size may be 242 tones (assuming J =4). As shown in the diagram, non-AP STA1 may be assigned 242-tone dRU-1, non-AP STA2 may be assigned 242-tone dRU-2, non-AP STA3 may be assigned 242-tone dRU-3, and non-AP STA4 may be assigned 242-tone dRU-4. The AP may store the AID and assigned dRU number for each non-AP STA.Phase 3

[0158] Based on conditions 1-4 mentioned above, the AP may determine which non-AP STAs to solicit an enhanced feedback report frame from and determine the dRU assignment for the non-AP STAs. The AP may then transmit an enhanced trigger frame to solicit the enhanced feedback report frame from the non-AP STAs to allow the AP to obtain feedback information regarding which non-AP STAs have buffered data to transmit and also to determine the channel condition of the operating bandwidth.

[0159] Figure 14 is a diagram showing a format of an enhanced trigger frame, according to some embodiments.

[0160] As shown in the diagram, an AP may transmit an enhanced trigger frame 1405. The enhanced trigger frame 1405 may include a MAC header 1410, a common information (“Common Info”) field 1415, a user information list (“User Info List”) field 1420, and a frame check sequence (FCS) field 1425, among other fields. The common information field 1415 may carry information regarding the PPDU bandwidth size (e.g., the operating bandwidth size) andthe dRU size (e.g., the dRU size may be determined based on phase 2 condition 4). The user information list field 1420 may include a user information field 1430 that carries information regarding the AID start number (e.g., the AID start number may be determined using phase 2 condition 2). For example, in the example shown in the diagram, the common information field 1415 includes an indication that the dRU size is 242 tones and the user information field 1430 includes an indication that the AID start number is 1000. It should be appreciated, however, that the dRU size and / or AID start number can be indicated in different fields of the enhanced trigger frame. The example shown in the diagram is provided by way of example only and should not be regarded as limiting.

[0161] The operations of the non-AP STAs when they receive the enhanced trigger frame from the AP are now described. The non-AP STAs that receive an enhanced trigger frame may perform operations in two phases: phase i and phase ii, which are described in additional detail herein below.Phase i

[0162] The non-AP STA may recognize the dRU size based on decoding the enhanced trigger frame (e.g., decoding the common information field included in the enhanced trigger frame). The non-AP STA may identify its own AID, which the AP assigned to the non-AP STA (e.g., in phase 1 condition 2). The non-AP STA may recognize the AID start number based on decoding the enhanced trigger frame (e.g., decoding the user information list field included in the enhanced trigger frame).

[0163] The non-AP STA may determine a dRU index based on its own AID and the AID start number. The dRU index may correspond to the dRU number on the AP side. Thus, the dRU index may identify a particular dRU. In an embodiment, the non-AP STA determines the dRU index according to the following equation:

[0164] dRU Tone lndex = 1 + (non-AP STA’s AID - starting number of AID)

[0165] In the equation above, “dRU Tone lndex” is the dRU index, “non-AP STA’s AID” is the AID assigned to the non-AP STA, and “starting number of AID” is the AID start number.

[0166] For example, if the non-AP STA’s AID is 1002 and the AID start number indicated in the enhanced trigger frame is 1002, then the non-AP STA may determine that the dRU index is 3 (dRU Tone lndex = 1 + (1002-1000) = 3). The non-AP STA may determine the dRU assigned to itself based on the dRU index and the dRU size indicated in the enhanced trigger frame. For example, if the dRU index is 3 and the dRU size is 242 tones, then the non-AP STA may recognize that it is assigned 242-tone dRU-3 specified by the 80 MHz dRU tone plan.

[0167] In an embodiment, the enhanced trigger frame includes a separate indication of the dRU assigned to each non-AP STA (e.g., in separate user information fields for each non-AP STA). For example, the enhanced trigger frame may include an indication that non-AP STA having AID 1000 is assigned to a first dRU, non-AP STA having AID having AID 1000+3 is assigned to a second dRU, and non-AP STA having AID 1000+7 is assigned to a third dRU. Each non-AP STA may determine the dRU assigned to itself based on the information included in the enhanced trigger frame. In an embodiment, the AP arranges the dRU assignment indications in order of AID (e.g., from smallest to largest). In this case, a non-AP STA that receives the enhanced trigger frame and determines that it has an AID that is smaller than the first AID indicated in the enhanced trigger frame may stop decoding the enhanced trigger frame at that point. For example, if the AP wishes to solicit an enhanced feedback report frame from non-AP STAs having AIDs 990, 1000, and 1003, the AP may transmit the enhanced trigger frame with dRU assignment indications arranged in order of AID 990, 1000, and 1003. A non- AP STA that receives the enhanced trigger frame and that has an AID that is smaller than 990 may immediately stop decoding the enhanced trigger frame after decoding the dRU assignment indication for AID 990. Such operation may be possible if an intermediate frame check sequence (FCS) field is added between the user info list field (e.g., user info list field 1420) and the FCS field (e.g., FCS field 1425). When non-AP STAs having different operating bandwidths are being assigned dRUs (e.g., non-AP STA having AID 990 may have a 20 MHz operating bandwidth, whereas the non-AP STAs having AIDs 1000 and 1003 may have a 40 MHz operating bandwidth), a question may arise regarding the dRU size to allocate (e.g., should they be allocated 20 MHz dRU tone plan dRUs or 40 MHz dRU tone plan dRUs). In an embodiment, the dRU assignment indicated in the enhanced trigger frame assigns dRUs only to non-AP STAs having the same operating bandwidth (e.g., only to non-AP STAs having AIDs in the 1000 series (i.e., AIDs between 1000 and 1999) or only to non-AP STAs having AIDs in the 2000 series (i.e., AIDs between 2000 and 2999)). This may prevent cases like the one mentioned above (the AID 990 / 1000 / 1003 case where different non-AP STAs may have different operating bandwidth) from occurring. In an embodiment, the dRU assignment assigns dRUs having dRU sizes that are commonly supported across operating bandwidths (e.g., 26-tone dRU or 56-tone dRUs).Phase ii

[0168] After receiving the enhanced trigger frame from the AP, a non-AP STA may transmit an enhanced feedback report frame. In an embodiment, the enhanced feedback report frame isan enhanced NDP feedback report frame. The enhanced NDP feedback report frame may be a null data packet (NDP) frame (that has no data payload). The enhanced feedback report frame may have a legacy preamble (e.g., that includes a L-STF field, a L-LTF field, a L-SIG field, a RL-SIG field, a U-SIG field, etc.), a UHR preamble (e.g., that includes a UHR-STF field), and a UHR-LTF (preamble) field (which may be considered part of the UHR preamble).

[0169] A non-AP STA may transmit an enhanced feedback report as follows. The non-AP STA may transmit the legacy preamble and UHR preamble of the enhanced NDP feedback report frame according to previous / future wireless networking standards. However, the non-AP STA may transmit the UHR-LTF field in a dRU assigned to the non-AP STA. Also, if the non- AP STA has buffered data to transmit, it may transmit the UHR-LTF field with all binary “l”s in the dRU assigned to the non-AP STA. However, if the non-AP STA does not have buffered data to transmit, it may transmit the UHR-LTF field with all binary “0”s in the dRU assigned to the non-AP STA.

[0170] Figure 15 is a diagram showing enhanced feedback report frames transmitted by non- AP STAs, according to some embodiments.

[0171] The example shown in the diagram assumes that four non-AP STAs are assigned dRUs according to the dRU assignment shown in Figure 13. That is, non-AP STA1 is assigned 242-tone dRU-1, non-AP STA2 is assigned 242-tone dRU-2, non-AP STA3 is assigned 242-tone dRU-3, and non-AP STA4 is assigned 242-tone dRU-4. Also, the example shown in the diagram assumes that the operating bandwidth is 80 MHz.

[0172] As shown in the diagram, non-AP STA1 may transmit an enhanced NDP feedback report frame with a legacy preamble, a UHR preamble, and a UHR-LTF field. The legacy preamble and UHR preamble may be transmitted in units of 20 MHz (e.g., when the dRU size is 242 tones or smaller, the preamble (legacy preamble and UHR preamble) should be transmitted in units of 20 MHz). Non-AP STA1 may transmit the UHR-LTF field in its assigned dRU (242-tone dRU-1). In this example, it is assumed that non-AP STA1 does not have any buffered data to transmit so it transmits all binary “0”s (encodes its assigned dRU with bit 0) in the UHR-LTF field.

[0173] Non-AP STA2 may also transmit an enhanced NDP feedback report frame with a legacy preamble, a UHR preamble, and a UHR-LTF field in a similar manner. However, non- AP STA2 may transmit the UHR-LTF field in its assigned dRU (242-tone dRU-2). In this example, it is assumed that non-AP STA2 does not have any buffered data to transmit so it transmits all binary “0”s (encodes its assigned dRU with bit 0) in the UHR-LTF field.

[0174] Non-AP STA3 may also transmit an enhanced NDP feedback report frame with a legacy preamble, a UHR preamble, and a UHR-LTF field in a similar manner. However, non- AP STA3 may transmit the UHR-LTF field in its assigned dRU (242-tone dRU-3). In this example, it is assumed that non-AP STA3 has buffered data to transmit so it transmits all binary “l”s (encodes its assigned dRU with bit 1) in the UHR-LTF field.

[0175] Non-AP STA4 may also transmit an enhanced NDP feedback report frame with a legacy preamble, a UHR preamble, and a UHR-LTF field in a similar manner. However, non- AP STA4 may transmit the UHR-LTF field in its assigned dRU (242-tone dRU-4). In this example, it is assumed that non-AP STA4 has buffered data to transmit so it transmits all binary “l”s (encodes its assigned dRU with bit 1) in the UHR-LTF field.

[0176] The non-AP STAs may transmit their respective enhanced NDP feedback report frames to the AP simultaneously.

[0177] Figure 16 is a diagram showing an enhanced NDP feedback report frame as received by the AP, according to some embodiments.

[0178] Continuing with the example provided above, the AP may receive an enhanced NDP feedback report frame from non-AP STA1, non-AP STA2, non-AP STA3, and non-AP STA 4. The enhanced NDP feedback report frame may have a legacy preamble, a UHR preamble, and a UHR-LTF field. As shown in the diagram, the UHR-LTF field that is received at the AP may be a merging of the UHR-LTF fields transmitted by non-AP STA1, non-AP STA2, non-AP STA3, and non-AP STA 4 in their respective assigned dRUs. Thus, the AP may receive the UHR-LTF field in four different dRUs with each dRU carrying an indication of whether the non-AP STA assigned to the dRU has buffered data to transmit. In this example, the portion of the UHR-LTF field received in 242-tone dRU-1 is filled with bit 0 indicating that non-AP STA1 does not have buffered data to transmit, the portion of the UHR-LTF field received in 242-tone dRU-2 is filled with bit 0 indicating that non-AP STA2 does not have buffered data to transmit, the portion of the UHR-LTF field received in 242-tone dRU-3 is filled with bit 1 indicating that non-AP STA3 has buffered data to transmit, and the portion of the UHR-LTF field received in 242-tone dRU-4 is filled with bit 1 indicating that non-AP STA4 has buffered data to transmit. Thus, the AP may determine which non-AP STAs have buffered data to transmit based on decoding the UHR-LTF field (which is transmitted / received in dRUs).

[0179] Figure 17 is a diagram showing a frame exchange sequence between the AP and non- AP STAs, according to some embodiments.

[0180] As shown in the diagram, the AP may transmit an enhanced trigger frame 1705 to the non-AP STAs to solicit an enhanced NDP feedback report frame from the non-AP STAs.Responsive to receiving the enhanced trigger frame 1705 from the AP, the non-AP STAs may simultaneously transmit an enhanced NDP feedback report frame, as described above. Notably, the non-AP STAs may transmit the UHR-LTF field of the enhanced NDP feedback report frame in their respectively assigned dRUs and include an indication in the UHR-LTF field of whether the non-AP ST A has buffered data to transmit.

[0181] After receiving the enhanced NDP feedback report frame from the non-AP STAs, the AP may operate in accordance with case 1 and / or case 2, which are described in additional detail herein below.Case 1

[0182] When the AP receives an enhanced feedback report frame from the non-AP STAs, the AP may determine which non-AP STAs have buffered data to transmit (and which non-AP STAs do not have buffered data to transmit) based on decoding the UHR-LTF field of the enhanced feedback report frame. The AP knows each non-AP STA’s AID and assigned dRU (e.g., the dRU index), and can use this knowledge when decoding the UHR-LTF field to determine which STAs have buffered data to transmit. The AP may then transmit a trigger frame to solicit an uplink trigger-based PPDU from the non-AP STAs that have buffered data to transmit (and not solicit an uplink trigger-based PPDU from any non-AP STAs that do not have buffered data to transmit). The trigger frame may include an indication of a dRU assignment. The dRU assignment may only assign dRUs to the non-AP STAs that have buffered data to transmit. By only assigning dRUs to STAs that have buffered data to transmit, interference between the uplink trigger-based PPDUs transmitted by non-AP STAs can be reduced.

[0183] Figure 18 is a diagram showing a frame exchange sequence for a case where some non-AP STAs do not have buffered data to transmit, according to some embodiments.

[0184] As shown in the diagram, the AP may transmit an enhanced trigger frame 1805 to solicit an enhanced NDP feedback report frame 1810 from non-AP STA1, non-AP STA2, non- AP STA3, and non-AP STA4. Responsive to receiving the enhanced trigger frame 1805, the non-AP STAs may transmit an enhanced NDP feedback report frame 1810 to the AP. The UHR-LTF field of the enhanced NDP feedback report frame 1810 received by the AP may indicate that non-AP STA1 and non-AP STA2 have no buffered data to transmit (e.g., the portion of the UHR-LTF field that is received in the dRUs assigned to non-AP STA1 and non- AP STA2 is filled with binary “0”s) but may indicate that non-AP STA3 and non-AP STA4 have buffered data to transmit (e.g., the portion of the UHR-LTF field that is received in the dRUs assigned to non-AP STA3 and non-AP STA4 is filled with binary “l”s). Accordingly, theAP may transmit a trigger frame 1815 that solicits an uplink trigger-based PPDU 1820 (UL TB PPDU) from non-AP STA3 and non-AP STA4 in dRUs (and does not solicit an uplink triggerbased PPDU from non-AP STA1 and non-AP STA2). The trigger frame 1815 may include an indication of a dRU assignment. The dRU assignment may assign dRUs to non-AP STA3 and non-AP STA4 (but not assign any RUs to non-AP STA1 and non-AP STA2). The dRU assignment may be the same or different from the dRU assignment that was used for transmitting the enhanced NDP feedback report frame 1810. Responsive to receiving the trigger frame 1815, non-AP STA3 and non-AP STA 4 may transmit the uplink trigger-based PPDU 1820 to the AP. The uplink trigger-based PPDU 1820 may include a legacy preamble, a UHR-STF field, a UHR-LTF field, and possibly other preamble fields. The uplink trigger-based PPDU 1820 may also include a data part for carrying a data payload. Non-AP STA3 and non- AP STA4 may transmit data in the data part in their respectively assigned dRUs. For example, non-AP STA3 may transmit its data in the data field in 242-tone dRU-3 and non-AP STA4 may transmit its data in the data field in 242-tone dRU-4. The other dRUs (242-tone dRUl and 242- tone dRU2) may be empty / unused. When the AP receives the uplink trigger-based PPDU 1820, it may decode the data included in the data part of the uplink trigger-based PPDU 1820 that was received in different dRUs. For example, the AP may obtain the data transmitted by non-AP STA3 by decoding the data received in 242-tone dRU-3 and decode the data transmitted by non- AP STA4 by decoding the data received in 242-tone dRU-4. The AP may then transmit a block acknowledgement (BA) frame 1825 to the non-AP STAs in response to receiving the uplink trigger-based PPDU 1820 ( to acknowledge successful reception of the uplink trigger-based PPDU 1820).Case 2

[0185] When the AP receives the enhanced feedback report frame from the non-AP STAs, the AP may determine that the enhanced feedback report frame was not properly received in at least a portion of the bandwidth. This may be the case if there is interference in the portion of the bandwidth or the portion of the bandwidth is suppressed due to some other reason. If the enhanced feedback report frame is not properly received in at least a portion of the bandwidth, the AP may divide the bandwidth into subblock(s) that do not include the portion of the bandwidth in which the enhanced feedback report frame was not properly received and assign dRUs within the subblock(s) to non-AP STAs. For example, if the operation bandwidth is 80 MHz (and the 80 MHz bandwidth is composed of a first 20 MHz portion, the second 20 MHz portion, a third 20 MHz portion, and a fourth 20 MHz portion) and the AP is not able to properlyreceive the enhanced feedback report frame in the second 20 MHz portion of the 80 MHz bandwidth, the AP may divide the 80MHz bandwidth into a 20 MHz subblock (e.g., comprised of the first 20 MHz portion of the 80 MHz bandwidth) and a 40 MHz subblock (e.g., comprised of the third 20 MHz portion and fourth 20 MHz portion of the 80 MHz bandwidth) and assign dRUs within the 20 MHz subblock (e.g., using a 20 MHz dRU tone plan) and dRUs within the 40 MHz subblock (e.g., using a 40 MHz dRU tone plan) to non-AP STAs.

[0186] Figure 19 is a diagram showing a frame exchange sequence for a case where an enhanced NDP feedback report frame is not properly received in at least a portion of the bandwidth, according to some embodiments.

[0187] As shown in the diagram, the AP may transmit an enhanced trigger frame 1905 to solicit an enhanced NDP feedback report frame 1910 from non-AP STA1, non-AP STA2, non- AP STA3, and non-AP STA4. Responsive to receiving the enhanced trigger frame, the non-AP STAs may transmit the enhanced NDP feedback report frame 1910 to the AP. In this example, as shown in the diagram, it is assumed that the AP is not able to properly receive the second 20 MHz portion of the 80 MHz bandwidth (the second from the top 20 MHz portion of the 80 MHz bandwidth). Thus, the AP may divide the 80 MHz bandwidth into a first subblock comprised of the first 20 MHz portion of the 80 MHz bandwidth and a second subblock comprised of the third and fourth 20 MHz portions of the 80 MHz bandwidth (so the subblocks exclude the second 20 MHz portion of the 80 MHz bandwidth), and assign dRUs within the first subblock and the second subblock to non-AP STAs that have buffered data to transmit. The AP may recognize which non-AP STAs have buffered data to transmit based on decoding the UHR-LTF field of the enhanced NDP feedback report frame 1910 in the portions of the bandwidth in which the enhanced NDP feedback report frame 1910 was properly received (e.g., the first, third, and fourth 20 MHz portions of the 80 MHz bandwidth). Since the dRUs are encoded with all binary “0”s (e.g., if a non-AP STA does not have buffered data to transmit) or all binary “l”s (e.g., if a non-AP STA has buffered data to transmit), even if the AP is not able to properly receive the UHR-LTF field in a portion of the bandwidth, the AP may still be able to infer the intended value (e.g., from other parts of the bandwidth). In this example, it is assumed that non- AP STA1 and non-AP STA2 do not have buffered data to transmit but that non-AP STA3 and non-AP STA4 have buffered data to transmit. Accordingly, the AP may transmit a trigger frame 1915 that solicits an uplink trigger-based PPDU 1920 from non-AP STA3 and non-AP STA4 (but does not solicit an uplink trigger-based PPDU from non-AP STA1 and non-AP STA2). The trigger frame 1915 may include an indication of a dRU assignment that assigns dRUs within the first subblock and / or the second subblock to non-AP STA3 and non-AP STA4(but not to non-AP STA1 and non-AP STA2). Responsive to receiving the trigger frame 1915, non-AP STA3 and non-AP STA 4 may transmit the uplink trigger-based PPDU 1920 to the AP. The uplink trigger-based PPDU 1920 may include a legacy preamble, a UHR-STF field, a UHR- LTF field, and possibly other preamble fields. The uplink trigger-based PPDU 1920 may also include a data part. Non-AP STA3 and non-AP STA4 may transmit data in the data part in their respectively assigned dRUs. For example, non-AP STA3 may transmit its data in the data field in its assigned dRU and non-AP STA4 may transmit its data in the data field in its assigned dRU. The second 20 MHz portion of the 80 MHz bandwidth (for the data part) may be empty / unused in the uplink trigger-based PPDU 1920. That is, the uplink trigger-based PPDU 1920 may be punctured in the second 20 MHz portion of the 80 MHz bandwidth (e.g., as shown in Figure 20) since that portion of the bandwidth is considered to have poor channel quality. The AP may receive the data part of the uplink trigger-based PPDU 1920 in different dRUs. For example, the AP may receive data transmitted by non-AP STA3 in one dRU and receive data transmitted by non-AP STA4 in another dRU. After receiving the uplink triggerbased PPDU 1920, the AP may transmit a BA frame 1925 to the non-AP STAs (to acknowledge successful reception of the uplink trigger-based PPDU 1920).

[0188] Figure 20 is a diagram showing an 80 MHz bandwidth that is divided into a 20 MHz subblock and a 40 MHz subblock, according to some embodiments.

[0189] As shown in the diagram, an 80 MHz bandwidth may be divided into a 20 MHz subblock and a 40 MHz subblock, with the second 20 MHz portion being punctured. When the 80 MHz bandwidth is not punctured, dRUs may be assigned within the 80 MHz bandwidth using a 80 MHz dRU tone plan. However, when the 80 MHz bandwidth is punctured and divided into a 20 MHz subblock and a 40 MHz subblock, dRUs may be assigned within the 20 MHz subblock using a 20 MHz dRU tone plan and dRUs may be assigned within the 40 MHz subblock using a 40 MHz dRU tone plan.

[0190] The frame exchange sequence described herein may allow an AP to determine which non-AP STAs have buffered data to transmit, which may allow the AP to only solicit uplink transmission from those non-AP STAs that have buffered data to transmit (and avoid soliciting uplink trigger-based PPDUs from non-AP STAs that do not have buffered data to transmit), which can reduce interference during the simultaneous uplink transmission. At the same time, the frame exchange sequence described herein may allow an AP to determine the channel condition of the operating bandwidth, which may allow the AP to avoid assigning dRUs that span portion(s) of the operating bandwidth that has poor channel quality, leading to a more efficient assignment and usage of dRUs.

[0191] Turning now to Figure 21, a method 2100 will be described for soliciting an uplink trigger-based PPDU in dRUs, in accordance with an example embodiment. The method 2100 may be performed by an AP. The AP may be implemented by a wireless device (e.g., wireless device 104).

[0192] Additionally, although shown in a particular order, in some embodiments the operations of the method 2100 (and the other methods shown in the other figures) may be performed in a different order. For example, although the operations of the method 2100 are shown in a sequential order, some of the operations may be performed in partially or entirely overlapping time periods.

[0193] At operation 2105, the AP transmits an enhanced trigger frame to solicit an enhanced feedback report frame, wherein a STA receiving the enhanced trigger frame is able to determine a dRU assigned to the STA based on information included in the enhanced trigger frame. In an embodiment, the enhanced trigger frame includes an indication of a PPDU bandwidth size, an indication of a dRU size, and an indication of an AID start number. In an embodiment, the STA receiving the enhanced trigger frame is able to determine the dRU assigned to the STA based on the PPDU bandwidth size, the dRU size, and the AID start number. In an embodiment, the enhanced trigger frame includes a common information field and a user information field, wherein the common information field includes the indication of the PPDU bandwidth size and the indication of the dRU size, and wherein the user information field includes the indication of the AID start number. In an embodiment, the dRU size is determined based on a number of STAs from which to solicit the enhanced feedback report frame. In an embodiment, the AP assigns AIDs to STAs associated with the AP based on operating bandwidths of the STAs.

[0194] At operation 2110, the AP receives the enhanced feedback report frame as a response to the enhanced trigger frame, wherein a preamble field of the enhanced feedback report frame is received in a plurality of dRUs with each of the plurality of dRUs carrying an indication of whether a STA assigned to the dRU has buffered data to transmit. In an embodiment, the preamble field is a UHR-LTF field.

[0195] At operation 2115, the AP determines STAs that have buffered data to transmit based on decoding the preamble field.

[0196] In an embodiment, at operation 2120, the AP determines that the enhanced feedback report frame was not properly received in a portion of a bandwidth.

[0197] In an embodiment, at operation 2125, responsive to determining that the enhanced feedback report frame was not properly received in the portion of the bandwidth, the AP generates a dRU assignment that assigns the STAs that have buffered data to transmit to dRUsthat do not span the portion of the bandwidth in which the enhanced feedback report frame was not properly received. In an embodiment, the bandwidth is divided into a first subblock and a second subblock that do not overlap with the portion in which the enhanced feedback report frame was not properly received, wherein the dRU assignment assigns the STAs that have buffered data to transmit to dRUs that span the first subblock or the second subblock. For example, if the bandwidth is a 80 MHz bandwidth comprised of a first 20 MHz portion, a second 20 MHz portion, a third 20 MHz portion, and a fourth 20 MHz portion, the first subblock may be comprised of the first 20 MHz portion, the portion in which the enhanced feedback report frame was not properly received may be the second 20 MHz portion, and the second subblock may be comprised of the third 20 MHz portion and the fourth 20 MHz portion.

[0198] At operation 2130, the AP transmits a trigger frame to solicit an uplink trigger-based PPDUs from the STAs that have buffered data to transmit. In an embodiment, as shown in block 2135, an indication of the generated dRU assignment is included in the trigger frame.

[0199] In an embodiment, at operation 2140, the AP receives the uplink trigger-based PPDU from the STAs that have buffered data to transmit in dRUs assigned to the STAs. Responsive to receiving the uplink trigger-based PPDU from the STAs that have buffered data to transmit, the AP may transmit a BA frame to those STAs.

[0200] Turning now to Figure 22, a method 2200 will be described for providing feedback information to an AP to allow the AP to solicit an uplink trigger-based PPDU in dRUs, in accordance with an example embodiment. The method 2200 may be performed by a STA. The STA may be implemented by a wireless device (e.g., wireless device 104).

[0201] At operation 2205, the STA receives an enhanced trigger frame from an AP.

[0202] At operation 2210, the STA determines a dRU assigned to the STA based on information included in the enhanced trigger frame. In an embodiment, the enhanced trigger frame includes an indication of a PPDU bandwidth size, an indication of a dRU size, and an indication of an AID start number, wherein the dRU assigned to the STA is determined based on the PPDU bandwidth size, the dRU size, and the AID start number. In an embodiment, the determining the dRU assigned to the STA comprises: determining a dRU index based on the AID start number and an AID assigned to the STA and determining the dRU assigned to the STA based on the dRU index and the dRU size. In an embodiment, the enhanced trigger frame includes a common information field and a user information field, wherein the common information field includes the indication of the PPDU bandwidth size and the indication of the dRU size, and wherein the user information field includes the indication of the AID start number.

[0203] At operation 2215, the STA transmits an enhanced feedback report frame to the AP as a response to the enhanced trigger frame, wherein a preamble field of the enhanced feedback report frame is transmitted in the dRU assigned to the STA and includes an indication of whether the STA has buffered data to transmit. In an embodiment, the preamble field is a UHR- LTF field.

[0204] In an embodiment, at operation 2220, the STA receives a trigger frame from the AP soliciting an uplink trigger-based PPDU from the STA, wherein the trigger frame includes an indication of a dRU assignment. In an embodiment, the dRU assignment assigns the STA to a same dRU as the dRU that was determined based on the information included in the enhanced trigger frame. In an embodiment, the dRU assignment assigns the STA to a different dRU from the dRU that was determined based on the information included in the enhanced trigger frame. In an embodiment, the different dRU spans a bandwidth that is smaller than a bandwidth in which the enhanced trigger frame is received.

[0205] In an embodiment, at operation 2225, responsive to receiving the trigger frame, the STA transmits the uplink trigger-based PPDU to the AP in a dRU assigned to the STA by the dRU assignment.

[0206] Although many of the solutions and techniques provided herein have been described with reference to a WLAN system, it should be understood that these solutions and techniques are also applicable to other network environments, such as cellular telecommunication networks, wired networks, etc. In some embodiments, the solutions and techniques provided herein may be or may be embodied in an article of manufacture in which a non-transitory machine-readable medium (such as microelectronic memory) has stored thereon instructions which program one or more data processing components (generically referred to here as a “processor” or “processing unit”) to perform the operations described herein. In other embodiments, some of these operations might be performed by specific hardware components that contain hardwired logic (e.g., dedicated digital filter blocks and state machines). Those operations might alternatively be performed by any combination of programmed data processing components and fixed hardwired circuit components.

[0207] In some cases, an embodiment may be an apparatus (e.g., an AP STA, a non-AP STA, or another network or computing device) that includes one or more hardware and software logic structures for performing one or more of the operations described herein. For example, as described herein, an apparatus may include a memory unit, which stores instructions that may be executed by a hardware processor installed in the apparatus. The apparatus may also includeone or more other hardware or software elements, including a network interface, a display device, etc.

[0208] Some portions of the preceding detailed descriptions have been presented in terms of algorithms and symbolic representations of operations on data bits within a computer memory. These algorithmic descriptions and representations are the ways used by those skilled in the data processing arts to most effectively convey the substance of their work to others skilled in the art. An algorithm is here, and generally, conceived to be a self-consi stent sequence of operations leading to a desired result. The operations are those requiring physical manipulations of physical quantities. Usually, though not necessarily, these quantities take the form of electrical or magnetic signals capable of being stored, combined, compared, and otherwise manipulated. It has proven convenient at times, principally for reasons of common usage, to refer to these signals as bits, values, elements, symbols, characters, terms, numbers, or the like.

[0209] It should be borne in mind, however, that all of these and similar terms are to be associated with the appropriate physical quantities and are merely convenient labels applied to these quantities. The present disclosure can refer to the action and processes of a computer system, or similar electronic computing device, that manipulates and transforms data represented as physical (electronic) quantities within the computer system's registers and memories into other data similarly represented as physical quantities within the computer system memories or registers or other such information storage systems.

[0210] The present disclosure also relates to an apparatus for performing the operations herein. This apparatus can be specially constructed for the intended purposes, or it can include a general-purpose computer selectively activated or reconfigured by a computer program stored in the computer. For example, a computer system or other data processing system may carry out the computer-implemented methods described herein in response to its processor executing a computer program (e.g., a sequence of instructions) contained in a memory or other non- transitory machine-readable storage medium. Such a computer program can be stored in a computer readable storage medium, such as, but not limited to, any type of disk including floppy disks, optical disks, CD-ROMs, and magnetic-optical disks, read-only memories (ROMs), random access memories (RAMs), EPROMs, EEPROMs, magnetic or optical cards, or any type of media suitable for storing electronic instructions, each coupled to a computer system bus.

[0211] The algorithms and displays presented herein are not inherently related to any particular computer or other apparatus. Various general-purpose systems can be used with programs in accordance with the teachings herein, or it can prove convenient to construct a more specialized apparatus to perform the method. The structure for a variety of these systems willappear as set forth in the description below. In addition, the present disclosure is not described with reference to any particular programming language. It will be appreciated that a variety of programming languages can be used to implement the teachings of the disclosure as described herein.

[0212] The present disclosure can be provided as a computer program product, or software, that can include a machine-readable medium having stored thereon instructions, which can be used to program a computer system (or other electronic devices) to perform a process according to the present disclosure. A machine-readable medium includes any mechanism for storing information in a form readable by a machine (e.g., a computer). In some embodiments, a machine-readable (e.g., computer-readable) medium includes a machine (e.g., a computer) readable storage medium such as a read only memory (“ROM”), random access memory (“RAM”), magnetic disk storage media, optical storage media, flash memory components, etc.

[0213] In the foregoing specification, embodiments of the disclosure have been described with reference to specific example embodiments thereof. It will be evident that various modifications can be made thereto without departing from the broader spirit and scope of embodiments of the disclosure as set forth in the following claims. The specification and drawings are, accordingly, to be regarded in an illustrative sense rather than a restrictive sense.

Claims

CLAIMSWhat is claimed is:

1. A method performed by an access point (AP) to solicit an uplink trigger-based physical layer protocol data unit (PPDU) in distributed tone resource units (dRUs), the method comprising: transmitting an enhanced trigger frame to solicit an enhanced feedback report frame, wherein a station (STA) receiving the enhanced trigger frame is able to determine a distributed tone resource unit (dRU) assigned to the STA based on information included in the enhanced trigger frame; receiving the enhanced feedback report frame as a response to the enhanced trigger frame, wherein a preamble field of the enhanced feedback report frame is received in a plurality of dRUs with each of the plurality of dRUs carrying an indication of whether a STA assigned to the dRU has buffered data to transmit; determining STAs that have buffered data to transmit based on decoding the preamble field; and transmitting a trigger frame to solicit the uplink trigger-based PPDU from the STAs that have buffered data to transmit.

2. The method of claim 1, wherein the preamble field is an ultra high reliability long training field (UHR-LTF) field.

3. The method of claim 1, wherein the enhanced trigger frame includes an indication of a PPDU bandwidth size, an indication of a dRU size, and an indication of an association identifier (AID) start number.

4. The method of claim 3, wherein the STA receiving the enhanced trigger frame is able to determine the dRU assigned to the STA based on the PPDU bandwidth size, the dRU size, and the AID start number.

5. The method of claim 4, wherein the enhanced trigger frame includes a common information field and a user information field, wherein the common information field includes the indication of the PPDU bandwidth size and the indication of the dRU size, and wherein the user information field includes the indication of the AID start number.

6. The method of claim 3, wherein the dRU size is determined based on a number of STAs from which to solicit the enhanced feedback report frame.

7. The method of claim 1, further comprising: determining that the enhanced feedback report frame was not properly received in a portion of a bandwidth; and responsive to determining that the enhanced feedback report frame was not properly received in the portion of the bandwidth, generating a dRU assignment that assigns the STAs that have buffered data to transmit to dRUs that do not span the portion of the bandwidth in which the enhanced feedback report frame was not properly received, wherein the dRU assignment is indicated in the trigger frame.

8. The method of claim 7, wherein the bandwidth is divided into a first subblock and a second subblock that do not overlap with the portion in which the enhanced feedback report frame was not properly received, wherein the dRU assignment assigns the STAs that have buffered data to transmit to dRUs that span the first subblock or the second subblock.

9. The method of claim 8, wherein the bandwidth is a 80 Megahertz (MHz) bandwidth comprised of a first 20 MHz portion, a second 20 MHz portion, a third 20 MHz portion, and a fourth 20 MHz portion, wherein the first subblock is comprised of the first 20 MHz portion, the portion in which the enhanced feedback report frame was not properly received is the second 20 MHz portion, and the second subblock is comprised of the third 20 MHz portion and the fourth 20 MHz portion.

10. The method of claim 1, further comprising: receiving the uplink trigger-based PPDU from the STAs that have buffered data to transmit in dRUs assigned to the STAs; and transmitting a block acknowledgement (BA) frame to the STAs that have buffered data to transmit.

11. The method of claim 1, further comprising: assigning AIDs to STAs associated with the AP based on operating bandwidths of the STAs.

12. A method performed by a station (STA) to provide feedback information to an access point (AP) for soliciting an uplink trigger-based physical layer protocol data units (PPDU) in distributed tone resource units (dRUs), the method comprising: receiving an enhanced trigger frame from an access point (AP); determining a distributed tone resource unit (dRU) assigned to the STA based on information included in the enhanced trigger frame; and transmitting an enhanced feedback report frame to the AP as a response to the enhanced trigger frame, wherein a preamble field of the enhanced feedback report frame is transmitted in the dRU assigned to the STA and includes an indication of whether the STA has buffered data to transmit.

13. The method of claim 12, wherein the preamble field is an ultra high reliability long training field (UHR-LTF) field.

14. The method of claim 12, wherein the enhanced trigger frame includes an indication of a PPDU bandwidth size, an indication of a dRU size, and an indication of an association identifier (AID) start number, wherein the dRU assigned to the STA is determined based on the PPDU bandwidth size, the dRU size, and the AID start number.

15. The method of claim 14, wherein the determining the dRU assigned to the STA comprises: determining a dRU index based on the AID start number and an AID assigned to the STA; and determining the dRU assigned to the STA based on the dRU index and the dRU size.

16. The method of claim 15, wherein the enhanced trigger frame includes a common information field and a user information field, wherein the common information field includes the indication of the PPDU bandwidth size and the indication of the dRU size, and wherein the user information field includes the indication of the AID start number.

17. The method of claim 12, further comprising: receiving a trigger frame from the AP soliciting an uplink trigger-based PPDU from the STA, wherein the trigger frame includes an indication of a dRU assignment; and responsive to receiving the trigger frame, transmitting the uplink trigger-based PPDU to the AP in a dRU assigned to the STA by the dRU assignment.

18. The method of claim 17, wherein the dRU assignment assigns the STA to a same dRU as the dRU that was determined based on the information included in the enhanced trigger frame.

19. The method of claim 17, wherein the dRU assignment assigns the STA to a different dRU from the dRU that was determined based on the information included in the enhanced trigger frame.

20. The method of claim 19, wherein the different dRU spans a bandwidth that is smaller than a bandwidth in which the enhanced trigger frame is received.

21. A wireless device to implement an access point (AP), the wireless device comprising: a radio frequency transceiver; a memory device storing a set of instructions; and a processor coupled to the memory device, wherein the set of instructions, when executed by the processor, causes the AP to perform the method of any one of claims 1-11.

22. A wireless device to implement a station (STA), the wireless device comprising: a radio frequency transceiver; a memory device storing a set of instructions; and a processor coupled to the memory device, wherein the set of instructions, when executed by the processor, causes the STA to perform the method of any one of claims 12-20.

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