Protection mechanism during txop sharing procedure between coordinated multiple aps

Abstract

Provided are techniques that can enable STAs that may be associated with a sharing AP to utilize a channel without having to excessively wait when they will not adversely impact transactions involving a shared AP. In this way, overall medium utilization may be enhanced without unreasonable risks of problematic interference. In some aspects, a method includes in a first access point (AP) device, generating a trigger frame with a transmission sharing opportunity (TXOP) having an associated TXOP duration, the frame including a MAC header timer duration that is less than the TXOP duration, and wirelessly transmitting the sharing opportunity trigger frame to one or more other access points (APs).

Description

SPECIFICATIONPROTECTION MECHANISM DURING TXOP SHARING PROCEDURE BETWEEN COORDINATED MULTIPLE APSCROSS-REFERENCE TO RELATED APPLICATION

[0001] This application claims the benefit of U.S. Provisional Application No. 63 / 584,420 filed September 21, 2023, which is hereby incorporated by reference.TECHNICAL FIELD

[0002] The present disclosure generally relates to wireless communications, and more specifically, relates to transmission opportunity sharing protections in a wireless network.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 and reliability. Additionally, 802.1 Ibe will introduce 4096-QAM (Quadrature AmplitudeModulation), 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.BRIEF DESCRIPTION OF THE DRAWINGS

[0005] 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.

[0006] Figure 1 A is a diagram showing a single BSS with an AP and multiple non-AP STAs.

[0007] Figure IB is a table illustrating operational parameters for various WiFi versions leading up to 802.1 Ibn.

[0008] Figure 2 is a block diagram illustrating a wireless device in accordance with some embodiments.

[0009] Figure 3 A is a diagram illustrating components of a WLAN device configured to transmit data in accordance with some embodiments.

[0010] Figure 3B is a diagram illustrating components of a WLAN device configured to receive data in accordance with some embodiments.

[0011] Figure 4 is a diagram illustrating Inter-Frame Space (IF S) relationships for WiFi transmissions in accordance with some embodiments.

[0012] Figure 5 is a diagram illustrating a Carrier Sense Multiple Access / Collision Avoidance (CSMA / CA) based frame transmission procedure for avoiding collisions between frames in a channel in accordance with some embodiments.

[0013] Figure 6A is a diagram showing the general structure of a trigger frame in accordance with some embodiments.

[0014] Figure 6B is a diagram illustrating an example trigger frame uplink (UL) transmission scenario in accordance with some embodiments.

[0015] Figure 6C illustrates an example trigger frame downlink (UL) transmission scenario in accordance with some embodiments.

[0016] Figures 7A and 7B show the general structures for EHT (WiFi 7) multi user and trigger based physical layer protocol data unit (PPDU) frames, respectively, in accordance with some embodiments.

[0017] Figure 7C is a table listing the fields and associated information for a TB PPDU in accordance with some embodiments.

[0018] Figure 7D is a table listing descriptions and information for sub fields in a universal signal (U-SIG) field for either a MU or TB PPDU frame in accordance with some embodiments.

[0019] Figure 8 is a diagram illustrating three BSSs with overlapping areas of coverage in accordance with some embodiments.

[0020] Figure 9 is a diagram illustrating TXOP transmissions involving STAs and APs in the three BSSs of Fig. 8 using traditional channel third-party contention rules.

[0021] Figure 10A is a diagram illustrating TXOP transmissions involving the STAs and APs of Fig. 8 where an OBSS station is allowed to prematurely reset its NAV timer prior to the TXOP duration expiring in accordance with some embodiments.

[0022] Figure 10B is a diagram showing an RTS-TXS trigger frame with a multi AP sharing indicator in accordance with some embodiments.

[0023] Figure 10C is a diagram showing a legacy MU-RTS-TXS frame with a multi AP sharing indicator in accordance with some embodiments.

[0024] Figures 10D and 10E are diagrams showing MU and TB PPDU frame structures that may include multi AP sharing indicators in accordance with some embodiments.

[0025] Figure 11 A is a diagram illustrating TXOP transmissions involving the STAs and APs of Figure 8 but with the sharing AP setting a reduced NAV time duration in accordance with some embodiments.

[0026] Figure 1 IB is a diagram showing a MU-RTS-TXS frame with an allocation duration sub field used to set an abbreviated NAV timer in accordance with some embodiments.

[0027] Figure 12A is a flow diagram showing a routine for an AP to generate a TXOP trigger frame in accordance with some embodiments.

[0028] Figure 12B is a flow diagram showing a routine for an AP to generate an RTS TXS frame for multi AP sharing in accordance with some additional embodiments.

[0029] Figure 12C is a flow diagram showing a routine for a station to process a TXOP trigger frame in a multi AP sharing scenario in accordance with some embodiments.DETAILED DESCRIPTION

[0030] As mentioned above, some of the objectives of the next generation of wireless networking standards (e.g., IEEE 802.1 Ibn or beyond IEEE 802.1 Ibe) include improving data rate and communication range. However, improving data rate and improving communication range are often competing objectives (there is a tradeoff between data rate and communication range). As will be discussed below, under multi AP sharing scenarios, some of the rules applied for previous and existing WiFi implementations impose inconvenient channel access restrictions on APs and non-AP STAs when they are at least partially in range of other BSSs but would not otherwise conflict with stations involved with the sharing activity. In some cases, they would be forced to wait for an unduly excessive NAV time period before attempting to access the channel. Accordingly, in some embodiments, provided are techniques that will enable STAs that may be associated with a sharing AP to utilize the channel without having to excessively wait when they will not adversely impact transactions involving a shared AP. In this way, overall medium utilization may be enhanced without unreasonable risks of problematic interference.

[0031] 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.

[0032] Figure 1 A 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.

[0033] 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).

[0034] Figure IB is a table illustrating operational parameters for various WiFi versions leading up to 802.1 Ibn, also referred to as WiFi 8 or UHR (Ultra High Reliability). The IEEE 802.1 Ibn (UHR) working group has been established to address the growing demand for higher peak throughput and reliability in Wi-Fi. As shown in Figure IB, 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 being considered.

[0035] The focus of IEEE 802.1 Ibe (EHT or WiFi 7) 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 320 MHz bandwidth and a more efficient utilization of a noncontiguous 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.

[0036] 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.

[0037] 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.

[0038] 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 GHz band (5.925 - 7.125 GHz) is being considered for unlicensed use. This would allow APs and STAs to become tri -band devices. Larger than 160 MHz 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.

[0039] 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.

[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, suchas 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 MEMO or MU-MIMO transmission, theRxSP 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 de-spreading the constellation points from the space-time streams into one or more spatial streams.

[0067] The demapper 314 de-maps 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 de-mapping before performing the constellation de-mapping.

[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 MEMO or MU-MIMO transmission, theRxSP 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 withthe 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’ (AIF S [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 dataframe, the management frame, and the control frame, which is not the response frame, may use the AIFSfAC] 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 second station STA2 receiving the data, and a third station STA3 that may be located in an area where a frame transmitted from the STA1 can be received, a frame transmitted from the second station STA2 can be received, or both can be received. The stations STA1, STA2, and STA3 may be WLAN devices 104 of Figure 1.

[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 SIFSthe 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] Figure 6A is a diagram showing the general structure of a trigger frame. A trigger frame is a control frame whose function is to allocate resources and solicit one or more Triggerbased (TB) Physical Layer Protocol Data Unit (PPDU) transmissions from associated stations including both AP and / or non-AP STAs. Among other things, they are used by APs to allocate resources for multi-user Orthogonal Frequency Division Multiple Access (OFDMA)transmissions. They specify how bandwidth and time slots should be divided among multiple STAs, enabling simultaneous data transmission from multiple users without interference. This is important for improving overall network efficiency and throughput, especially in environments with high user density.

[0090] As illustrated in the figure, trigger frames generally include several different sections including a MAC (media access control) header section 605, a common information section 610, and a user information section 615. The MAC header includes several fields that facilitate communication between devices. For example, they may include Frame Control (FC), Duration (or Duration / ID), Receiver Address (RA), and Transmitter Address (TA) fields as shown. The FC field indicates protocol Version, type, and several different flags for parameters such as power management. The duration field indicates the duration for which the medium is reserved, or in some implementations, it may carry the association identifier (AID) in certain contexts. The RA field indicates the address of a recipient STA, and the TA field indicates the address of the transmitting STA. The MAC header may also include fields for sequence and QoS Control.

[0091] Trigger frames have specific subfields within the frame Control field that are used for its operation including the trigger frame type, e.g., basic trigger, MU-BAR (multi-user block acknowledgment request, and MU-RTS (multi-user request to send. Each of these subtypes has unique characteristics and requirements for operation, especially in multi-user scenarios where coordination is important for efficient communication.

[0092] The common Info section 610 includes parameters such as the expected uplink length, bandwidth, guard interval, and the transmit power used by the AP. These parameters help STAs prepare for their upcoming transmissions.

[0093] The different fields in the common info field serve to inform the responding STAs on how they should set up the frame in the response. The response to a MU-RTS is a legacy CTS frame in the non-HT format. At 5GHz that means legacy OFDM. Most of the subfields in the common info field for MU-RTS may therefore not be needed. For the included fields, trigger type is set to 3 for MU-RTS requests; More TF is used for TWT or power save with UORA (otherwise set to 00; and the CS Required is set to 0 if the responding STAs are not required to consider the medium or the NAV in determining whether or not to respond. CS Required is set to 1 if responding STAs are required to use ED (Energy Detect) to sense and consider the medium and the NAV in determining whether or not to respond. The UL BW is usually used to describe the bandwidth of the response in the TB PPDU, but for MU-RTS, it may describe the bandwidth of the frame carrying the MU-RTS (e.g., 0=20 MHz, 1=40 MHz, 2=80 MHz, and 3=80 + 80 MHz or 160 MHz).

[0094] The user info section 615 includes details for each participating STA, such as Association IDs (AIDs), Resource Unit (RU) allocations, Modulation and Coding Scheme (MCS), and an expected Received Signal Strength Indicator (RSSI). This information allows each STA to know its specific transmission parameters. The AID12 field indicates the STA-id (associations ID) for each recipient. Other values used in this space are used in other variants of the trigger frame. RU allocation is used to indicate which primary channel the responding CTS should be sent on. This is particular to 40 MHz and 80 MHZ channels, whether the primary channel are the lowest channel, next lowest channel, and so on. The user info fields are typically repeated for every STA that is a recipient of the MU-RTS. The receiving STAs are addressed by their association ID, STA-id, not by MAC-addresses as in legacy RTS. There may be other information depending on specific trigger frame types. The User Info field in a trigger frame, such as in a MU-RTS trigger frame, may also include an allocation duration subfield. This subfield indicates a time allocated by the AP for the STA to transmit during the TXOP. The field can contain an allocation duration subfield, which indicates the duration of time allocated for P2P communications associated with the client device. This allocation duration subfield is used for managing the transmission time and allowing other devices to set their network allocation vectors (NAVs) accordingly.

[0095] Figure 6B illustrates an example trigger frame uplink (UL) transmission scenario in accordance with some embodiments. In the IEEE 802.11 specification versions since 802.1 lax (WiFi 6), the trigger frame plays a useful role in facilitating both uplink and downlink multi-user (MU) transmissions.

[0096] 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.

[0097] With the example scenario of Figure 6B, an access point (AP) operating in an 80 MHz bandwidth environment sends a trigger frame to multiple associated STAs to allow them to perform uplink data transmissions. Upon receiving the Trigger frame, the STAs respond by sending their respective CTS response frames. CTS (clear to send) frames are the response to a MU-RTS. All STAs that are addressed in the user info field of a MU-RTS trigger frame should respond with a CTS if they wish to participate in an uplink transmission. When the STAs send their CTS, they use the TA address, the address of the STA (AP) that should receive the CTS. The AP then sends a transmission to initiate uplink transmission from the STAs that responded appropriately. From here, the STAs transmit orthogonal frequency division multiple access (ULOFDMA) TB PPDUs utilizing the allocated resources within the specified 80 MHz bandwidth. 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 80 MHz 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.

[0098] Figure 6C illustrates an example trigger frame downlink (DL) transmission scenario in accordance with some embodiments. It’s similar to the uplink procedure except it facilitates bulk data transmissions from the AP to the STAs rather than from the STAs to the AP. The AP sends to the STAs a multi user RTS, e.g., MU-RTS-TXS for request to send downlink transmissions to the STAs. The process begins with the AP sending a MU RTS TXS trigger frame to the non- AP STA(s). Upon receiving this frame, the STAs are expected to respond with a CTS frame, indicating that they are ready to receive the data. From here, the AP transmits to the STAs that responded MU PPDUs, which include data intended for the STAs. Finally, the STAs respond with acknowledgement frames back to the AP.

[0099] Figures 7A and 7B show the general structures for EHT (WiFi 7) multi user and trigger based physical layer protocol data unit (PPDU) frames, respectively. (It is expected that the UHR PPDUs will be the same or similar. For simplicity, EHT examples may be used here and in other parts of this disclosure, but it should be appreciated that UHR and later specification parameters may equally be implemented.) With reference to Figure 7A, a MU PPDU can be sent to a single user or to multiple users. The frame has legacy (705 A) and contemporary (710A) preamble sections, along with data and packet extension field sections. The legacy section includes a legacy short training field (L-STF), legacy long training field (L-LTF) and a legacy signal field (L-SIG). The contemporary section includes a universal signal field (U-SIG), an EHT signal field (EHT-SIG), an EHT short training field (EHT-STF), an EHT long training field (EHT-LTF), data fields for the actual data payload, and a packet extension (PE) field. The EHT-SIG field, along with the U-SIG field, provides RU (resource unit) allocations and other information the STAs need to understand the MU packet. When the MU PPDU is sent to multiple users, the transmission can be OFDMA or MU-MIMO.

[0100] With reference to Figure 7B, upon receiving a trigger based RTS from an AP, a STA may use the EHT TB PPDU to respond to the trigger from the AP. The EHT TB frame format is similar to the MU PPDU. However, the TB PPDU does not include the EHT-SIG preamblefield, and it includes a repeated legacy (RL) signal field in the legacy section. In addition, the EHT-STF field may be two times longer than in the EHT MU PPDU in order to improve performance and reliability for uplink transmissions. Figure 7C is a table listing the fields, along with additional information, for a TB PPDU. Figure 7D is a table listing descriptions and information for sub fields in a universal signal (U-SIG) field for either a MU or TB PPDU frame.

[0101] The preamble is a design component used to provide information relevant for the receiver to decode the transmitted data. It is also used to provide backward compatibility with previous PHY versions. However, the preamble typically does not directly conveyed the PHY version of the packet. Auto detection (or spoofing) mechanisms have been created for receivers to implicitly determine the PHY versions. However, the auto detection algorithms have had to become more complex. EHT attempts to solve this problem with the universal signal (U-SIG) field. The U-SIG comes after the legacy and RL SIG fields and is 2 OFDM symbols in length. It includes version independent and version dependent bits. The version independent bits are the first 20 bits of the U-SIG and have the same location and definition for EHT and later PHYs. The first 3 bits (bits 0 to 2) are used to identify the PHY version, which simplifies auto detection. The next 3 bits (bits 3 to 5) indicate the spectrum occupancy of the PPDU (e.g., 80 MHz bandwidth). The 7th bit (bit 6) signals the link direction (i.e., uplink or downlink). The next 6 bits (bits 7 to 12) identify the basic service set (BSS) in use via the BSS color and the 7 TXOP bits (bits 13 to 19) provide information on how long the PPDU uses the medium. The U- SIG bits / fields remainder depends on the PHY version and PPDU type.

[0102] To provide flexibility and prepare for possible new capabilities, EHT classifies the reserved bits in the EHT preamble as "disregard" or "validate". This classification helps a receiver determine the appropriate action if it comes across a bit value that is not used in a PHY it supports. Disregard means ignore this bit and continue reception. Validate means check if the bit matches a known value and if not, terminate reception. As an example, values 1 to 7 in the PHY version identifier field will correspond to a future IEEE802.11 PHY version not recognized by a device supporting the current EHT version. If a baseline EHT device receives a value other than 0 (0 indicates EHT PHY), the device should stop reception.

[0103] 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 andreduced latency, the wireless network system can evolve toward a hybrid ARQ (HARQ) approach.

[0104] 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.

[0105] 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.

[0106] In a second type of HARQ scheme, also referred to as an incremental redundancy (IR) HARQ (IR-HARQ) scheme, different puncturing patterns are used for each subpacket such that the signal changes for each retransmitted subpacket in comparison to the originally transmitted subpacket. IR-HARQ alternatively uses two puncturing patterns for odd numbered and even numbered transmissions, respectively. The redundancy scheme of IR-HARQ improves the log likelihood ratio (LLR) of parity bit(s) in order to combine information sent across different transmissions due to requests and lowers the code rate as the additional subpacket is used. This results in a lower error rate of the subpacket in comparison to CC-HARQ. The puncturing pattern used in IR-HARQ is indicated by a subpacket identity (SPID) indication. The SPID of the first subpacket may always be set to 0 and all the systematic bits and the punctured parity bits are transmitted in the first subpacket. Self-decoding is possible when the receiving signal-to-noise ratio (SNR) environment is good (i.e., a high SNR). In some embodiments, subpackets with corresponding SPIDs to be transmitted are in increasing order of SPID but can be exchanged / switched except for the first SPID.

[0107] 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 desired.

[0108] In the context of coordinated TDMA (C-TDMA), the AP that has 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.

[0109] Various different M-AP technologies have been, and are being, discussed. They include coordinated beamforming (CBF), coordinated spatial reuse (CSR), joint transmission (JTX), and OFDMA / TDMA. Coordinated beam-forming / nulling involves multiple APs transmitting on the same frequency resource based on the coordination and formation of spatial nulls to allow for simultaneous transmission from multiple APs. Interference between the M- APs is reduced through the sharing of channel state information (CSI). With coordinated spatial reuse (C-SR), multiple APs and / or STAs adjust the transmit power to reduce interference between stations (APs, non-AP STA). With joint transmission (JTX) schemes, multiple APs jointly transmit to a given user simultaneously by sharing data between the APs. In effect, the multiple APs act as a single, virtual AP. With coordinated OFDMA / TDMA schemes, M-APs use time and frequency in a cooperative manner to increase system throughput. They transmit on orthogonal frequency resources by coordinating and splitting the spectrum to use it more efficiently.

[0110] With reference to Figure 8, contemporary WiFi implementations (e.g., UHR) permit new methods of TXOP sharing that allow a sharing AP to share its obtained transmission opportunity (TXOP) with other APs, referred to as “shared” APs. Fig. 8 is a diagram illustrating three BSSs with overlapping areas of coverage. The BSSs include BSS1, BSS2, and BSS3, each with an associated AP, API, AP2, and AP3, respectively. API has two associated non-AP stations (STA1-1, STA1-2); AP2 has two associated non-AP stations (STA2-1, STA2-2), andAP3 has one associated non-AP station (STA3-1), as are indicated in the figure. With this example, API is a sharing AP, sharing its TXOP with AP2, which is referred to as the shared AP. AP3 is not directly involved with the TXOP sharing, but it can hear at least some of the transmissions from either or both BSS1 or BSS2. In this capacity, it is referred to as an overhearing AP. Accordingly, BSS1 is a sharing BSS; BSS2 is a shared BSS and BSS3 is an overhearing BSS (OBSS).

[0111] Unfortunately, as will be discussed below, some of the rules used for previous and existing WiFi implementations impose inconvenient restrictions on APs and non-AP STAs when they realize they are at least partially in range of other transmitting stations. They are forced to wait for an unduly excessive NAV time period before attempting to access the channel. Accordingly, in some embodiments, provided are techniques that will enable STAs that are hidden to Shared APs and not associated with Sharing AP. to utilize the channel without having to excessively wait when they will not adversely impact transactions involving the shared AP. In this way, overall medium utilization may be enhanced without unreasonable risks of problematic interference.

[0112] Before discussing techniques relating to multi AP sharing, some background will be given pertaining to existing AP to non-AP STA TXOP sharing in order to put them in better perspective. With 802.1 Ibe (EHT) an AP may allocate time within an obtained TXOP to an associated non-AP STA by transmitting a MU-RTS-TXS trigger frame. From here, the STA, after receiving the MU-RTS TXS trigger frame (containing a User Info field addressed to it) from its associated AP may transmit one or more non-TB PPDUs within the time allocated in the MU-RTS TXS trigger frame. After sending the CTS solicited by an MU-RTS TXS trigger frame, the STA ignores the intra-BSS NAV until the end of the time allocation signaled in the MU-RTS TXS Trigger frame, as it has access to the channel for transmitting data. On the other hand, the STA does not received PHY-RXSTART indication from the PHY during the NAV timeout, and it is not permitted to reset its NAV. An STA that uses information from a received MU-RTS TXS trigger frame as the most recent basis to update its NAV should not reset its NAV after the NAV Timeout has expired unless the STA receives a satisfactory CF-End frame. This applies to the STAs in the BSS that are not participating in the TXOP exchange. Even when an STA that is not participating in the TXS procedure does not overhear a CTS frame during an NAV timeout, it still may not reset its NAV. This is justified, however, in order to protect recipient STA(s) of the MU-RTS-TXS to transmit one or more PPDUs without interference from other STAs within the same BSS.

[0113] WiFi 8 (UHR) introduces extended TXOP sharing, e.g., allowing a TXOP acquired by a sharing AP to be shared with single or multiple other APs. With TXOP sharing between multiple APs (M-APs), protection of additional STAs may be needed to allow the shared AP to transmit or solicit PPDUs in its BSS within the allocated time without undue interference from STAs in nearby BSSs, as well as from the same BSS. However, in some scenarios, e.g., where an STA is relevant to the TXOP sharing AP but not to the shared AP’s BSS, it would be beneficial to allow the STA to contend for channel access within the allocated TXOP time

[0114] Fig. 9 is a diagram illustrating TXOP transmissions involving STAs and APs in the three BSSs of Fig. 8 using traditional channel third-party contention rules. With this example, API is a sharing AP, AP2 is a shared AP and AP3 is an over-hearing AP in an over-hearing BSS (OBSS3). The sharing AP (API) and shared AP (AP2) exchange frames to carry out the TXOP transaction. API sends a MU-RTS-TXS frame, which is picked up and responded to with a CTS frame from AP2. AP2 uses the shared time to transmit data between itself and one or more of its stations, e.g., STA2-1, as is shown in the figure. The data transmission is completed with STA2- 1 sending an acknowledgement frame (BA) back to AP2.

[0115] With this example, two of the STAs (AP3, STA1-2) can overhear the MU-RTS TXS TF from API but cannot hear transmissions from stations in BSS2. Notwithstanding, under existing rules, they cannot reset their NAV timers. This may be justified with STA1-2 because it should not be allowed to interfere with the API transmitting its PPDUs within the allocated time. However, AP3 would not cause collisions with the stations in BSS2, but as shown in the figure, it still does not reset its NAV until the end of the allocated TXOP time, which is a waste of available resources.

[0116] Accordingly, in some embodiments, processes for efficiently utilizing channel resources while avoiding channel contention during TXOP sharing between multiple APs is are presented. If a station (e.g., UHR station) would not adversely affect a shared AP’s BSS within the allocated TXOP duration, it should be allowed to contend for channel access without having to wait for the TXOP timer duration to expire. In some embodiments, techniques for allowing such STAs to use a channel without having to wait for a whole TXOP duration are provided. In some embodiments, when a station determines it is not part of the same BSS as the sharing AP, it may reset its NAV and attempt to access the channel. With yet additional embodiments, the AP generating the MU-RTS-TXS can set a smaller duration in the MAC header (e.g., in a Duration / ID field) than the duration for the TXOP. This smaller NAV timer duration may be long enough for sharing exchange control activity (e.g., SIFS + response frame duration or SIFS + response frame duration + a short duration sufficient to transmit a few pending frames) but notcovering the entire TXOP sharing duration. In fact, in some embodiments, it may even be set to 0.

[0117] Fig. 10A is a diagram illustrating TXOP transmissions involving the STAs and APs of Fig. 8 where an OBSS station is allowed to prematurely reset its NAV timer prior to the TXOP duration expiring in accordance with some embodiments. With this example, the same basic TXOP transaction takes place between API, AP2 and STA2-1 as in Fig. 9. That is, API shares its TXOP with AP2, which uses it to transmit data between itself and its associated station(s), STA2-1 in this example. However, with this scenario, AP3 may reset its NAV timer before the TXOP duration expires. It can do this because it has determined that the TXOP is for sharing between APs and that it is not associated with the sharing AP (API). Accordingly, it is allowed to reset its NAV timer before expiration of the entire TXOP duration. The over-hearing stations may make these determinations in any suitable manner, examples of which are discussed below. In some embodiments, relevant frames may include one or more fields with data to allow a station to determine if multi AP sharing is taking place and whether it is associated with the sharing AP.

[0118] Figure 10B is a diagram showing an MU-RTS-TXS trigger frame with a multi AP sharing indicator in accordance with some embodiments. With this implementation, an EHT, or later, MU-RTS TXS trigger frame includes an indicator in the user section indicating TXOP sharing between APs. For example, the indicator may be disposed within one of the subfields or a reserved subfield in the User Info field, as shown in Figure 10B at 1005. Here, a bit indication is included to signify the TXOP sharing between Aps (BSSs).

[0119] Upon receiving a MU-RTS TXS PPDU with such an indication set, STAs such as UHR STAs should interpret the remaining fields of the User Info even if it's not specifically addressed to them. For OBSS STAs which are hidden from the Shared AP, the basic NAV (e.g., as defined in the Duration / ID field of the MAC header) is adhered to during the transmission of the MU-RTS TXS and CTS frames, but after that time, they are allowed to attempt wireless channel occupancy. Since TXOP permission for the channel is granted to the Shared AP, which is hidden from OBSS STAs, the OBSS STAs do not need to unnecessarily prolong the NAV configuration during the transmitted and shared TXOP period. This approach provides an advantage of OBSS STAs being able to attempt channel access without unnecessary delays.

[0120] On the other hand, if the received frame is an intra-BSS frame (STA is associated with the sharing AP), and the User Info field indicates that the frame is not destined for them, the STA should still set their intra-BSS NAV for the duration specified in the Allocation Duration subfield of the user section. Moreover, a STA, when receiving a MU-RTS TXS frametransmitted from a BSS belonging to the same group, should not perform a NAV Reset even if it does not receive a CTS frame during the NAV timeout period. Note that in some embodiments, BSSs classified as being part of the same group include MYBSS (STAs affiliated with same AP), BSSs that belong to the same ESS, and a set of BSSs grouped together for multi operation purposes.

[0121] Fig. 10C is a diagram showing a legacy MU-RTS-TXS frame with a multi AP sharing indicator in accordance with some embodiments. With this example, the MU-RTS TXS frame specifies partial BSS information (e.g., BSS ID information) in the AID12 field of the user info field in place of traditional AID information. This is indicated in the figure at 1010. In this case, the included BSS information can represent Color information or partial BSS ID, e.g., with reduced bit width, instead of a 48-bit BSS ID field. For example, partial BSS ID, an AP ID, or BSS color information can be represented with a 12-bit width as one of the subfields in the User Info field.

[0122] Figures 10D and 10E show MU and TB PPDU frame structures that may include multi AP sharing indicators in accordance with some embodiments. BSS information identifying the participating TXOP BSSs can be included in either of the signal fields, for example. In the depicted example, BSS information is included in the universal signal (U-SIG) fields (1015, 1020) for the MU and TB PPDUs, respectively.

[0123] Fig. 11 A is a diagram illustrating TXOP transmissions involving the STAs and APs of Figure 8 but with the sharing AP setting a reduced NAV time duration in accordance with some embodiments. With this example, the same basic TXOP transaction takes place between API, AP2 and STA2-1. That is, API shares it TXOP with AP2, which uses it to transmit data between itself and one or more of its associated station(s), STA2-1 in this example. However, with this scenario, AP3 does not have to prematurely reset the designated NAV duration on its own because it has already been defined by the sharing AP to be smaller than the duration available for the entire TXOP sharing opportunity.

[0124] Figure 1 IB is a diagram showing a MU-RTS-TXS frame with a Duration / ID field (1105) used to set this abbreviated NAV timer, used by OBSS stations, and an Allocation Duration field 1110 in the User section for the TXOP duration. For example, the sharing AP may set the duration in the Duration / ID 1105 to a time to account for response and pending frames but not for the entire TXOP duration. By configuring the duration field to the minimum time necessary for single protection, or even setting it to a zero duration, it becomes possible to mitigate the issue effectively. In other words, considering a scenario where the duration field value is defined as SIFS+CTS-air-Time in the MU-RTS TXS frame transmitted by the SharingAP, and where an OBSS STA listens exclusively to this MU-RTS TXS frame without receiving any corresponding responses, the duration value set in this context is shorter than the NAV timer for the whole TXOP allotment. Consequently, an NAV for that specific duration is established for the OBSS station, aligning with existing WiFi standards that prohibit NAV resets. As a result, the Basic NAV is upheld for the specified duration value, and once the OBSS NAV counter reaches zero, the OBSS stations become eligible to attempt channel occupancy. In this way, since TXOP permission for the channel is granted to the shared AP, which is hidden from the OBS stations, the OBSS stations do not need to unnecessarily prolong the NAV configuration during the transmitted and shared TXOP period.

[0125] In some embodiments, a more proactive approach involves setting the duration field of a MU-RTS TXS frame transmitted by the Sharing AP to 0. This approach can be considered in scenarios where STAs, both associated with the Sharing AP and hidden from the Shared AP, may receive the MU-RTS TXS frame but are unable to receive the response frame. For the associated STAs of the Sharing AP, they can set their intra-BSS NAV using information from the User Info field of the MU-RTS TXS PPDU to avoid impacting the Shared AP during the shared TXOP period.

[0126] As for the OBSS STAs hidden from the Shared AP, since the duration in the MU-RTS TXS frame is set to 0, they can immediately begin a backoff process. However, it's important to consider potential collisions, especially when OBSS STAs are within the transmission range of CTS frames from the Shared AP.

[0127] In scenarios where the Shared AP determines that TXOP sharing is not needed, it can decline the TXOP sharing request by not responding, effectively rejecting the request. When the Sharing AP encounters a CTS Timeout, it can naturally infer that its TXOP share request was declined by the Shared AP. In such situations, the Sharing AP can perform PIFS recovery or, after the CTS timeout, immediately transmit a CF-end frame, allowing wireless resources to be acquired by all around STAs through backoff contention. The scenario where the Shared AP rejects TXOP sharing aligns with the perspective of OBSS STAs or associated STAs of the Sharing AP when they receive a MU-RTS TXS frame but do not receive a CTS response thereafter. OBSS stations can reset their NAV timeout after the NAV timeout period, allowing them to regain access to the channel, while the associated STAs of the Sharing AP continue to maintain their intra-BSS NAV timeout.

[0128] Figure 12A is a flow diagram showing a routine 1200 for an AP to generate a TXOP trigger frame in accordance with some embodiments. At 1202, a first access point (AP) device generates a trigger frame with a sharing opportunity (TXOP) that has an associated TXOPduration. For example, the trigger frame may be a MU-RTS-TXS trigger frame. In some embodiments, this TXOP duration corresponds to the amount of time to the time being allocated to a shared AP receiving the transmission opportunity.

[0129] At 1204, the AP includes in the frame a timer duration that is less than the TXOP duration. For example, this timer duration may correspond to the time for response (e.g., CTS), a SIFS, and any pending frame(s). In some embodiments, this timer duration may even be as small as 0. In some embodiments, the timer duration is in a Duration / ID field of a MAC header section. In some embodiments, the timer duration is a second duration, and the AP is to set a first duration, corresponding to the TXOP duration, in a user section of the trigger frame with the second timer duration being smaller than the first timer duration. In some embodiments, the user section may also, or alternatively, include a BSS identifier field.

[0130] At 1206, the AP wirelessly transmits the sharing opportunity trigger frame to one or more other access points (Aps). In some embodiments, the trigger frame may also include a user section that includes a field to indicate the opportunity sharing is between multiple access points.

[0131] In some embodiments, the AP may generate a physical layer protocol data unit (PPDU) having a universal signal (U-SIG) or version specific (e.g., EHT-SIG, UHR-SIG or later) field with participating BSS information, and wirelessly transmit the PPDU to the other AP. For example, the participating BSS information could include at least one of a coordinated multiple AP operation or a multiple AP sharing activity.

[0132] Figure 12B is a flow diagram showing a routine 1210 for an AP to generate a trigger frame for multi AP sharing in accordance with additional embodiments. At 1212, the AP generates a trigger frame with a TXOP having an associated TXOP duration.

[0133] At 1214, the AP includes in the frame multi BSS sharing information to allow a station not associated with a shared AP to reset its NAV timer prior to an end of the TXOP duration. At 1216, it wirelessly transmits the sharing opportunity trigger frame to one or more other access points.

[0134] Figure 12C is a flow diagram showing a routine 1220 for a station to process a TXOP trigger frame in a multi AP sharing scenario in accordance with some embodiments. At 1222, a station wirelessly receives a trigger frame with a sharing opportunity.

[0135] Next, at 1224, the station determines that the frame request is from a first AP to one or more other APs. At 1226, it determines if it (the station) is in an associated BSS of the first AP. At 1228, it sets an NAV timer using duration information from the frame based on whether it is associated with the first AP and / or with any shared AP accepting the request.

[0136] In some embodiments, the duration information is in a MAC header section of the frame. In some embodiments, it determines if the STA is in the associated BSS by processing BSS color information from a PPDU or by processing BSS identification information from an associated identifier (AID) section of the frame. In some embodiments, the duration is less than a sharing opportunity duration associated with the sharing opportunity of the trigger frame.

[0137] 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.

[0138] In some cases, an embodiment may be an apparatus (e.g., an AP STA, a non-AP STA, or another network or computing device) that includes one or more hardware and software logic structures for performing one or more of the operations described herein. For example, as described herein, an apparatus may include a memory unit, which stores instructions that may be executed by a hardware processor installed in the apparatus. The apparatus may also include one or more other hardware or software elements, including a network interface, a display device, etc.

[0139] 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.

[0140] It should be bome 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.

[0141] 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.

[0142] The algorithms and displays presented herein are not inherently related to any particular computer or other apparatus. Various general-purpose systems can be used with programs in accordance with the teachings herein, or it can prove convenient to construct a more specialized apparatus to perform the method. The structure for a variety of these systems will appear as set forth in the description below. In addition, the present disclosure is not described with reference to any particular programming language. It will be appreciated that a variety of programming languages can be used to implement the teachings of the disclosure as described herein.

[0143] 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.

[0144] 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, comprising: in a first access point (AP) device, generating a trigger frame with a transmission sharing opportunity (TXOP) having an associated TXOP duration, the frame including a MAC header timer duration that is less than the TXOP duration; and wirelessly transmitting the sharing opportunity trigger frame to one or more other access points (APs).

2. The method of claim 1, wherein the MAC header timer duration corresponds to a time for the first AP to receive a response frame from the one or more other APs but less than is available for the one or more other APs to use the TXOP.

3. The method of claim 2, wherein the MAC header timer duration corresponds to a time for an SIFS plus the response frame or a time for an SIFS plus the response frame plus a duration sufficient to transmit one or more pending frames.

4. The method of claim 2, wherein the response frame is in a TB PPDU (Trigger-Based Physical Protocol Data Unit) frame.

5. The method of claim 2, wherein the response frame is a CTS frame.

6. The method of claim 1, wherein the MAC header timer duration corresponds to a network allocation vector (NAV) timer.

7. The method of claim 1, wherein the trigger frame includes a user section that includes a field to indicate the opportunity sharing to be between multiple access points.

8. The method of claim 1, wherein the TXOP duration is in a user section of the trigger frame.

9. The method of claim 1, wherein the trigger frame includes a user section including an AP identifier field.

10. The method of claim 9, wherein the TXOP duration is in a user section of the trigger frame.

11. The method of claim 1, wherein the TXOP duration is a first timer duration and the AP is to set a second timer duration in a media access control (MAC) section of the trigger frame, the second timer duration being less than the first timer duration.

12. The method of claim 11, wherein the first timer duration is in a user section of the trigger frame.

13. The method of claim 12, wherein the second timer duration in the MAC section is set to zero.

14. The method of claim 1 comprising generating a physical layer protocol data unit (PPDU) having a universal signal (U-SIG) field with participating BSS information and wirelessly transmitting the PPDU.

15. The method of claim 14, wherein the participating BSS information includes at least one of a coordinated multiple AP operation or a multiple AP sharing activity.

16. A non-transitory machine readable medium having instructions that when executed perform a method as recited in any of claims 1-15.

17. A method, comprising: in a first access point (AP) device, generating a physical layer protocol data unit (PPDU) having a signal field with participating BSS information, and wirelessly transmitting the PPDU to a station (STA).

18. The method of claim 17, wherein the STA is a non-AP STA.

19. The method of claim 17, wherein the participating BSS information includes at least one of a coordinated multiple AP operation or a multiple AP sharing activity.

20. The method of claim 17, wherein the PPDU is a multi-user (MU) PPDU.

21. The method of claim 17, wherein the signal field is a universal signal (U-SIG) field.

22. A non-transitory machine readable medium having instructions that when executed perform a method as recited in any of claims 17-21.

23. A method, comprising: in a station (STA), wirelessly receiving a trigger frame that includes a sharing opportunity including a first duration associated with the sharing opportunity; determining the frame is from a first AP to one or more other APs; determining if the STA is in an associated BSS of the first AP; and setting an NAV timer using a second duration from the frame that is less than the first duration, or resetting the NAV timer, if the STA is not in the BSS associated with the first AP.

24. The method of claim 23, wherein the first duration information is in a user section of the trigger frame.

25. The method of claim 23, wherein determining if the STA is in the associated BSS includes processing BSS color information from a PPDU.

26. The method of claim 23, wherein determining if the STA is in the associated BSS includes processing BSS identification information from an associated identifier (AID) section of the trigger frame.

27. The method of claim 23, comprising interpreting all of the fields of a user section even if the trigger frame is not addressed to the STA.

28. The method of claim 23, comprising setting the NAV timer to the first duration if the STA determines it is in the associated BSS of the first AP.

29. A non-transitory machine readable medium having instructions that when executed perform a method as recited in any of claims 23-28.

30. A method, comprising: in an AP, generating a trigger frame having a TXOP with an associated first duration; including in the frame multi BSS sharing information to allow a station not associated with a shared AP to reset its NAV timer prior to an end of the first duration; and wirelessly transmitting the sharing opportunity trigger frame to one or more other access points.

31. The method of claim 30, wherein the frame includes a second duration that is less than the first duration.

32. The method of claim 31, wherein the second duration is in a MAC header section of the trigger frame, and the first duration is in a user section of the trigger frame.

33. A method, comprising: in a first access point (AP) device, wirelessly receiving a physical layer protocol data unit (PPDU) from a station (STA), the PPDU including a signal field with participating BSS information; and processing the (PPDU).

34. The method of claim 33, wherein the STA is a second AP device.

35. The method of claim 33, wherein the participating BSS information includes at least one of a coordinated multiple AP operation or a multiple AP sharing activity.

36. The method of claim 33, wherein the PPDU is a multi-user (MU) PPDU.

37. The method of claim 33, wherein the signal field is a universal signal (U-SIG) field.

38. A non-transitory machine readable medium having instructions that when executed perform a method as recited in any of claims 33-37.

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