Extended Limited Target Wake Time (e-rTWT) scheme for Multiple Basic Service Set (BSS) environments

Abstract

This specification discloses a method performed by an access point (AP) of a basic service set (BSS) for scheduling a restricted target wake time (rTWT) service period (SP). The method comprises sending a frame containing restricted target wake time service period scheduling information for scheduling a restricted target wake time service period, which includes a first section on which one or more members of a BSS can transmit data, and a second section on which one or more members of overlapping BSSs (OBSSs) that overlap with the BSS but are not members of the BSS can transmit data.

Description

Technical Field

[0001] [Cross - reference to Related Applications] This application claims the benefit of U.S. Provisional Application No. 63 / 509,265, titled "Multi - AP resource management by using Enhanced Restricted Target Wake Time (e - rTWT) parameter set in OBSS network conditions in beyond IEEE 802.11be," filed on June 20, 2023, which is hereby incorporated by reference in its entirety.

[0002] The present disclosure generally relates to wireless communication and, more specifically, to an enhanced restricted target wake time scheme for multiple basic service set (BSS) environments.

Background Art

[0003] IEEE 802.1 1 is a set of physical and media access control (MAC) specifications for implementing wireless local area network (WLAN) communications. These specifications provide the basis for wireless network products using the Wi-Fi brand, which is managed and defined by the Wi-Fi® Alliance. These specifications define the use of the 2.400–2.500 gigahertz (GHz) and 4.915–5.825 GHz bands. These spectral bands are commonly referred to as the 2.4 GHz band and the 5 GHz band. Each spectrum is subdivided into channels with a central frequency and bandwidth. The 2.4 GHz band is divided into 14 channels, each spaced 5 megahertz (MHz) apart, although the availability of these channels is restricted in some countries. The 5GHz band is more strictly regulated than the 2.4GHz band, with channel spacing varying across the spectrum, and a minimum spacing of 5MHz depending on the regulations of each country or region.

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

[0005] Restricted target wake time (rTWT) is a feature that enables access points (APs) to provide enhanced media access protection and resource reservation in wireless networks to achieve more predictable latency, reduced worst-case latency, and / or higher reliability for latency-sensitive traffic. Traditional rTWT schemes are designed for a single basic service set (BSS) environment. In high-density network environments, overlapping BSS (OBSS) interference can cause transmission to fail during the BSS's rTWT service period (SP). [Brief explanation of the drawing]

[0006] This disclosure will be better understood from the detailed description presented below and from the accompanying drawings of various embodiments of this disclosure. However, these drawings should not be construed as limiting this disclosure to any particular embodiment, but are merely for illustrative and illustrative purposes.

[0007] [Figure 1] This figure shows an exemplary wireless local area network (WLAN) having a basic service set (BSS) including multiple wireless devices, according to some embodiments of the present disclosure.

[0008] [Figure 2] This is a schematic diagram of a wireless device according to some embodiments of the present disclosure.

[0009] [Figure 3A] This figure shows components of a wireless device configured to transmit data, according to some embodiments of the present disclosure.

[0010] [Figure 3B]This figure shows components of a wireless device configured to receive data, according to some embodiments of the present disclosure.

[0011] [Figure 4] This figure shows the inter-frame space (IFS) relationships in some embodiments of the present disclosure.

[0012] [Figure 5] This figure shows a carrier-sense multiple access / collision avoidance (CSMA / CA) based frame transmission procedure according to some embodiments of the present disclosure.

[0013] [Figure 6] This figure shows a table comparing various iterations of the Institute of Electrical and Electronics Engineers (IEEE) 802.11 standard according to some embodiments of the present disclosure.

[0014] [Figure 7] This figure shows a table illustrating the fields of an Extreme High Throughput (EHT) frame format according to some embodiments of the present disclosure.

[0015] [Figure 8] This diagram shows the limitations of the conventional rTWT method.

[0016] [Figure 9] This figure shows an extended rTWT parameter set notified by a single AP in several embodiments.

[0017] [Figure 10] This figure shows both the AP for BSS and the AP for OBSS, indicating an extended rTWT parameter set according to several embodiments.

[0018] [Figure 11] A diagram showing a frame exchange sequence for a first type of rTWT SP according to some embodiments.

[0019] [Figure 12] A diagram showing a frame exchange sequence for a second type of rTWT SP according to some embodiments.

[0020] [Figure 13] A diagram showing a frame exchange sequence for a third type of rTWT SP according to some embodiments.

[0021] [Figure 14] A diagram showing channel splitting according to some embodiments.

[0022] [Figure 15] A flowchart showing another method of scheduling rTWT SP according to some embodiments.

[0023] [Figure 16] A flowchart showing another method of transmitting data during a first type of rTWT SP according to some embodiments.

[0024] [Figure 17] A flowchart showing another method of transmitting data during a second type of rTWT SP according to some embodiments.

[0025] [Figure 18] A flowchart showing another method of transmitting data during a third type of rTWT SP according to some embodiments.

Best Mode for Carrying Out the Invention

[0026] One aspect of this disclosure relates generally to wireless communication, and more specifically to an extended restricted target waketime scheme for multiple basic service set (BSS) scenarios.

[0027] As mentioned above, the conventional rTWT method is designed for a single basic service set (BSS) environment. In high-density network environments, overlapping BSS (OBSS) interference can cause transmission to fail during the BSS's rTWT service period (SP).

[0028] This specification introduces an extended restricted target wake time (rTWT) scheme suitable for use in multi-BSS environments. The extended rTWT scheme can schedule rTWT SPs that allow members of BSS and members of OBSS overlapping with BSS to transmit data without collisions. Three types of rTWT SPs are described herein: 1) A first type of rTWT SP allows OBSS members to transmit data during an rTWT SP when they have low-latency data to transmit; 2) A second type of rTWT SP allows OBSS members to compete for a channel during an rTWT SP under certain conditions (e.g., when the channel is idle for a predetermined period); 3) A third type of rTWT SP allows members of BSS and OBSS to transmit simultaneously during an rTWT SP by having BSS members transmit data using a primary channel and OBSS members transmit data using a secondary channel.

[0029] According to the extended rTWT scheme disclosed herein, members of the OBSS may transmit low-latency data between rTWT SPs of the BSS, thereby reducing the delay of the low-latency data in the OBSS. Furthermore, the extended rTWT scheme ensures that there are no collisions between BSS transmissions and OBSS transmissions between rTWT SPs, thereby protecting the rTWT SPs. The extended rTWT scheme may be used in next-generation wireless standards (e.g., those beyond IEEE 802.11be) to protect rTWT SPs in multi-BSS environments.

[0030] To protect rTWT SPs in a multi-BSS environment, one or more APs may notify members of the BSS and members of one or more OBSSs of the scheduling information for the rTWT SPs so that both BSS and OBSS members can recognize the scheduled rTWT SPs for scheduling the rTWT SPs. The scheduling information for the rTWT SPs may include information about the scheduled rTWT SPs, such as the start time and duration (or end time) of the rTWT SPs. An STA receiving the scheduling information for the rTWT SPs may terminate any transmissions before the rTWT SPs start in order to protect the rTWT SPs. In one embodiment, the scheduling information for the rTWT SPs takes the form of an extended rTWT parameter set. The extended rTWT parameter set may include one or more parameters from the conventional rTWT parameter set and one or more additional parameters to support the extended rTWT scheme (for example, parameters to support one or more of the three types of rTWT SPs described above).

[0031] According to some embodiments, an AP of a BSS transmits a frame containing scheduling information for a restricted target waketime service period, which includes a first section on which one or more members of the BSS can transmit data, and a second section on which one or more members of an OBSS that overlap with the BSS but are not members of the BSS can transmit data. An AP or STA receiving the frame may determine, based on the scheduling information for the restricted target waketime service period contained in the frame, when the first section of the restricted target waketime service period occurs and when the second section of the restricted target waketime service period occurs. Members of the BSS may transmit data during the first section of the restricted target waketime service period, but may refrain from transmitting any data during the second section of the restricted target waketime service period. Similarly, members of an OBSS may refrain from transmitting any data during the first section of the restricted target waketime service period, but may transmit a data frame during the second section of the restricted target waketime service period. In this way, members of BSS and OBSS can have the opportunity to transmit data between rTWT SPs without collisions, which helps reduce the delay of low-latency data.

[0032] For illustrative purposes, various embodiments are described herein in the context of wireless networks based on the IEEE 802.11 standard, and using its terminology and concepts. Those skilled in the art will understand that the embodiments disclosed herein may be modified / adapted for use in other types of wireless networks.

[0033] In the following detailed description, only specific embodiments of the present invention are shown and described as illustrative. As those skilled in the art will recognize, all of the embodiments described can be modified in various different ways without departing from the spirit or scope of the invention. Accordingly, the drawings and description are provided as illustrative and not limiting. Throughout this specification, similar reference numerals indicate similar elements.

[0034] Figure 1 shows a wireless local area network (WLAN) 100 having a basic service set (BSS) 102 including a plurality of wireless devices 104 (which may be referred to as WLAN devices 104). Each of the wireless devices 104 may include a media access control (MAC) layer and a physical (PHY) layer in accordance with the IEEE (Institute of Electrical and Electronics Engineers) standard 802.11, including one or more revisions, such as 802.11a / b / g / n / p / ac / ax / bd / be. In one embodiment, the MAC layer of wireless device 104 may initiate the transmission of a frame to another wireless device 104 by passing a PHY-TXSTART.request(TXVECTOR) to the PHY layer. The TXVECTOR provides parameters for generating and / or transmitting the corresponding frame. Similarly, the PHY layer of a receiving wireless device may generate an RXVECTOR containing parameters of the received frame, which is passed to the MAC layer for processing.

[0035] The multiple wireless devices 104 may include wireless device 104A, which is an access point (sometimes referred to as an AP station or AP STA), and other wireless devices 104B1-104B4, which are not AP stations (sometimes referred to as non-AP STAs). Alternatively, all of the multiple wireless devices 104 may be non-AP STAs in an ad-hoc networking environment. Generally, AP STAs (e.g., wireless device 104A) and non-AP STAs (e.g., wireless devices 104B1-104B4) may be collectively referred to as STAs. However, for the sake of clarity, only non-AP STAs may be referred to as STAs. Although shown using four non-AP STAs (e.g., wireless devices 104B1-104B4), the WLAN 100 may include any number of non-AP STAs (e.g., one or more wireless devices 104B).

[0036] Figure 2 shows a schematic block diagram of a wireless device 104 according to one embodiment. The wireless device 104 may be wireless device 104A (i.e., AP of WLAN 100) or one of wireless devices 104B1 to 104B4 in Figure 1. The wireless device 104 includes a baseband processor 210, a radio frequency (RF) transceiver 240, an antenna unit 250, a storage device (e.g., a memory device) 232, one or more input interfaces 234, and one or more output interfaces 236. The baseband processor 210, storage device 232, input interface 234, output interface 236, and RF transceiver 240 can communicate with each other via a bus 260.

[0037] The baseband processor 210 performs baseband signal processing and includes a MAC processor 212 and a PHY processor 222. The baseband processor 210 may utilize memory 232, which may include a non-temporary computer / machine-readable medium in which software (e.g., computer / machine programming instructions) and data are stored.

[0038] In one embodiment, the MAC processor 212 includes a MAC software processing unit 214 and a MAC hardware processing unit 216. The MAC software processing unit 214 can implement a first set of functions of the MAC layer by executing MAC software that may be contained in software stored in a storage device 232. The MAC hardware processing unit 216 can implement a second set of functions of the MAC layer in dedicated hardware. However, the MAC processor 212 is not limited to these. For example, depending on the implementation, the MAC processor 212 may be configured to execute the first and second sets of functions entirely in software or entirely in hardware.

[0039] The PHY processor 222 includes a transmitting (TX) signal processing unit (SPU) 224 and a receiving (RX) SPU 226. The PHY processor 222 implements multiple functions of the PHY layer. These functions can be performed in software, hardware, or a combination thereof, depending on the implementation.

[0040] The functions performed by the transmitting SPU224 may include one or more of the following: forward error correction (FEC) coding, parsing of streams into one or more spatial streams, diversity coding of spatial streams into multiple spatiotemporal streams, spatial mapping of spatiotemporal streams to a transmission chain, inverse Fourier transform (IFT) calculation, cyclic prefix (CP) insertion to create guard intervals (GI). The functions performed by the receiving SPU226 may include the inverse of the functions performed by the transmitting SPU224, such as GI removal and Fourier transform calculation.

[0041] The RF transceiver 240 includes an RF transmitter 242 and an RF receiver 244. The RF transceiver 240 is configured to transmit first information received from the baseband processor 210 to the WLAN 100 (for example, to another WLAN device 104 of the WLAN 100) and to provide second information received from the WLAN 100 (for example, from another WLAN device 104 of the WLAN 100) to the baseband processor 210.

[0042] The antenna unit 250 includes one or more antennas. When Multiple-Input Multiple-Output (MIMO) or Multi-User MIMO (MU-MIMO) is used, the antenna unit 250 may include multiple antennas. In one embodiment, the antennas in the antenna unit 250 may operate as a beamforming antenna array. In one embodiment, the antennas in the antenna unit 250 may be directional antennas, which may be fixed or steerable.

[0043] The input interface 234 receives information from the user, and the output interface 236 outputs information to the user. The input interface 234 may include one or more of the following: a keyboard, keypad, mouse, touchscreen, microphone, and the like. The output interface 236 may include one or more of the following: a display device, touchscreen, speaker, and the like.

[0044] As described herein, many functions of the WLAN device 104 may be implemented in either hardware or software. Which functions are implemented in software and which in hardware depends on the constraints imposed on the design. These constraints may include one or more of the following: design cost, manufacturing cost, time to market, power consumption, available semiconductor technology, etc.

[0045] As described herein, a wide variety of electronic devices, circuits, firmware, software, and combinations thereof may be used to implement the functionality of the components of the WLAN device 104. Furthermore, the WLAN device 104 may include other components that are omitted for brevity, such as an application processor, memory interface, clock generator circuit, power supply circuit, and the like.

[0046] Figure 3A shows the components of a WLAN device 104 configured to transmit data according to one embodiment, which include a transmitting (Tx) SPU (transmitting SPU: TxSP) 324, an RF transmitter 342, and an antenna 352. In one embodiment, the TxSP 324, RF transmitter 342, and antenna 352 correspond to the transmitting SPU 224, RF transmitter 242, and antenna of the antenna unit 250 in Figure 2, respectively.

[0047] The TxSP324 includes an encoder 300, an interleaver 302, a mapper 304, an inverse Fourier transformer (IFT) 306, and a guard interval (GI) inserter 308.

[0048] The encoder 300 receives and encodes input data. In one embodiment, the encoder 300 includes a forward error correction (FEC) encoder. The FEC encoder may include a binary convolution code (BCC) encoder and a subsequent puncturing device. The FEC encoder may also include a low-density parity-check (LDPC) encoder.

[0049] The TxSP324 may further include a scrambler to scramble the input data before encoding is performed by the encoder 300 to reduce the probability of long sequences of 0s or 1s. If the encoder 300 performs BCC encoding, the TxSP324 may further include an encoder parser to demultiplex the scrambled bits across multiple BCC encoders. If LDPC encoding is used within the encoder, the TxSP324 does not need to use an encoder parser.

[0050] The interleaver 302 interleaves the bits of each stream output from the encoder 300, changing the order of the bits inside. The interleaver 302 may apply interleaving only when the encoder 300 is performing BCC encoding; otherwise, it may output the stream from the encoder 300 without changing the order of the bits inside.

[0051] Mapper 304 maps the sequence of bits output from interleaver 302 to constellation points. If encoder 300 performs LDPC coding, mapper 304 may also perform LDPC tone mapping in addition to constellation mapping.

[0052] When TxSP324 performs MIMO or MU-MIMO transmission, TxSP324 may include multiple interleavers 302 and multiple mappers 304 depending on the number of spatial streams (NSS) of the transmission. TxSP324 may further include a stream parser for dividing the output of encoder 300 into blocks and transmitting these blocks to different interleavers 302 or mappers 304, respectively. TxSP324 may further include a space-time block code (STBC) encoder for expanding constellation points from spatial streams into a number of space-time streams (NSTS), and a spatial mapper for mapping space-time streams to a transmission chain. The spatial mapper may use direct mapping, spatial augmentation, or beamforming.

[0053] IFT306 converts the constellation point blocks output from mapper 304 (or the spatial mapper if MIMO or MU-MIMO is being performed) into time-domain blocks (i.e., symbols) using the inverse discrete Fourier transform (IDFT) or the inverse fast Fourier transform (IFFT). When an STBC encoder and spatial mapper are used, IFT306 may be provided for each transmission chain.

[0054] When TxSP324 performs MIMO or MU-MIMO transmission, TxSP324 may insert cyclic shift diversity (CSD) to prevent unintended beamforming. TxSP324 may insert CSD before or after IFT306. CSD may be specified per transmission chain or per spatiotemporal stream. Alternatively, CSD may be applied as part of a spatial mapper.

[0055] When TxSP324 performs MIMO or MU-MIMO transmission, several blocks may be provided for each user before the spatial mapper.

[0056] The GI inserter 308 prepends a GI to each symbol generated by the IFT 306. Each GI may contain a cyclic prefix (CP) corresponding to the repeating portion at the end of the symbol preceding the GI. The TxSP 324 may optionally perform windowing to smooth the edges of each symbol after inserting the GI.

[0057] The RF transmitter 342 converts the symbols into RF signals and transmits these RF signals via the antenna 352. When the TxSP324 performs MIMO or MU-MIMO transmission, a GI inserter 308 and an RF transmitter 342 may be provided for each transmission chain.

[0058] Figure 3B shows the components of a WLAN device 104 configured to receive data according to one embodiment, which include a receiver (Receiver: Rx) SPU (Receiver SPU: RxSP) 326, an RF receiver 344, and an antenna 354. In one embodiment, the RxSP 326, RF receiver 344, and antenna 354 may correspond to the receiving SPU 226, RF receiver 244, and antenna of the antenna unit 250 in Figure 2, respectively.

[0059] The RxSP326 includes a GI remover 318, a Fourier transformer (FT) 316, a demapper 314, a deinterleaver 312, and a decoder 310.

[0060] The RF receiver 344 receives the RF signal via the antenna 354 and converts the RF signal into symbols. The GI remover 318 removes the GI from each of the symbols. If the received transmission is a MIMO or MU-MIMO transmission, the RF receiver 344 and the GI remover 318 may be provided for each receiving chain.

[0061] The FT316 transforms each symbol (i.e., each time-domain block) into a frequency-domain block of a constellation point using either the Discrete Fourier Transform (DFT) or the Fast Fourier Transform (FFT). The FT316 may be provided for each receiving chain.

[0062] If the received transmission is a MIMO or MU-MIMO transmission, the RxSP326 may include a spatial demapper that converts the output of each FT316 in the receiver chain into a constellation point of multiple spatiotemporal streams, and an STBC decoder that spreads the constellation point from the spatiotemporal stream into one or more spatial streams.

[0063] The demapper 314 demaps the constellation points output from the FT316 or STBC decoder into a bitstream. If the received transmission was encoded using LDPC coding, the demapper 314 may perform LDPC tone demapping before performing constellation demapping.

[0064] The deinterleaver 312 deinterleaves the bits of each stream output from the demapper 314. The deinterleaver 312 may perform deinterleaving only if the received transmission was encoded using BCC coding; otherwise, it may output the stream output by the demapper 314 without performing deinterleaving.

[0065] If the received transmission is a MIMO or MU-MIMO transmission, the RxSP326 may use multiple demappers 314 and multiple deinterleavers 312 corresponding to the number of spatial streams of the transmission. In this case, the RxSP326 may further include a stream deparser for combining the streams output from the deinterleavers 312.

[0066] The decoder 310 decodes the stream output from the deinterleaver 312 or stream deparser. In one embodiment, the decoder 310 includes an FEC decoder. The FEC decoder may include a BCC decoder or an LDPC decoder.

[0067] The RxSP326 may further include a descrambler for descrambling the decoded data. If the decoder 310 performs BCC decoding, the RxSP326 may further include an encoder deparser for multiplexing data decoded by multiple BCC decoders. If the decoder 310 performs LDPC decoding, the RxSP326 does not need to use an encoder deparser.

[0068] Before transmitting, wireless devices such as wireless device 104 will use Clear Channel Assessment (CCA) to evaluate the availability of the wireless medium. If the medium is occupied, the CCA may determine that it is busy; on the other hand, if the medium is available, the CCA may determine that it is idle.

[0069] IEEE 802.11 PHY entities are based on orthogonal frequency division multiplexing (OFDM) or orthogonal frequency division multiple access (OFDMA). In either OFDM or OFDMA physical (PHY) layer, an STA (e.g., radio device 104) can send and receive physical layer (PHY) protocol data units (PPDUs) that comply with the required PHY specification. The PHY specification defines the set of modulation and coding schemes (MCS) and the maximum number of spatial streams. Some PHY entities have a maximum number of space-time streams (STS) per user and define downlink (DL) and uplink (UL) multi-user (MU) transmissions that employ a maximum of a predetermined total number of STS. The PHY entity may provide support for continuous channel widths of 10 megahertz (MHz), 20 MHz, 40 MHz, 80 MHz, 160 MHz, 240 MHz, and 320 MHz, and support for non-continuous channel widths of 80+80, 80+160 MHz, and 160+160 MHz. Each channel contains multiple subcarriers, which may also be referred to as tones. The PHY entity may define signaling fields within the PPDU, such as Legacy Signal (L-SIG), Signal A (SIG-A), Signal B (SIG-B), and similar, which convey some necessary information regarding PHY Service Data Unit (PSDU) attributes. For completeness and brevity, the following description refers to OFDM-based 802.11 technology. Unless otherwise indicated, "station" refers to a non-AP STA.

[0070] Figure 4 shows the frame interval (IFS) relationships. In particular, Figure 4 shows the Short IFS (SIFS), Point Coordination Function (PCF) IFS (PIFS), Distributed Coordination Function (DCF) IFS (DIFS), and Arbitration IFS (AIFS[i]) corresponding to Access Category (AC) "i". Figure 4 also shows the slot time, where data frames are used to transmit data to be transferred to the upper layer. As shown, if the DIFS has elapsed while the medium is idle, the WLAN device 104 performs a backoff and then transmits a data frame.

[0071] Management frames may be used to exchange management information that is not forwarded to higher layers. Subtypes of management frames include beacon frames, association request / response frames, probe request / response frames, and authentication request / response frames.

[0072] Control frames can be used to control access to a medium. Subtypes of control frames include request to send (RTS) frames, clear to send (CTS) frames, and acknowledgment (ACK) frames.

[0073] When the control frame is not a response frame to another frame, the WLAN device 104 sends the control frame after performing a backoff if DIFS has elapsed while the medium is idle. When the control frame is a response frame to another frame, the WLAN device 104 sends the control frame after SIFS has elapsed without performing a backoff or checking whether the medium is idle.

[0074] A WLAN device 104 that supports Quality of Service (QoS) functionality (i.e., a QoS STA) may transmit a frame after performing a backoff if the AIFS (i.e., AIFS[AC]) for the associated access category (AC) has elapsed. When transmitted by a QoS STA, any data frame, administration frame, or control frame other than a response frame may use the AIFS[AC] of the AC of the transmitted frame.

[0075] If a WLAN device 104 that is ready to forward a frame discovers that the medium is busy, the WLAN device 104 may perform a backoff procedure. The backoff procedure involves determining a random backoff time consisting of N backoff slots, where each backoff slot has a time length equal to the slot time, and N is an integer greater than or equal to zero. The backoff time may be determined according to the length of the Contention Window (CW). In one embodiment, the backoff time may be determined according to the AC of the frame. All backoff slots occur following a DIFS or Extended IFS (EIFS) period, during which the medium is determined to be idle for the duration of that period.

[0076] If the WLAN device 104 detects that there has been no activity on the media for a specified backoff slot duration, the backoff procedure must decrement the backoff time by the slot duration. If the WLAN device 104 determines that the media is busy during the backoff slot, the backoff procedure is paused until the media is again determined to be idle for a duration of the DIFS or EIFS period. When the backoff timer reaches zero, the WLAN device 104 may transmit or retransmit frames.

[0077] The backoff procedure works such that when multiple WLAN devices 104 are waiting to transmit and the backoff procedure is executed, each WLAN device 104 can select a backoff time using a random function, and the WLAN device 104 that selects the shortest backoff time wins the competition and reduces the probability of collision.

[0078] Figure 5 shows a carrier-sensing multiple access / collision avoidance (CSMA / CA) based frame transmission procedure for avoiding collisions between frames within a channel, according to one embodiment. Figure 5 shows a first station STA1 that transmits data, a second station STA2 that receives the data, and a third station STA3 that may be located in an area where frames transmitted from STA1 can be received, frames transmitted from the second station STA2 can be received, or both can be received. Stations STA1, STA2, and STA3 may be the WLAN device 104 in Figure 1.

[0079] Station STA1 can determine whether a channel is busy by carrier sense. Station STA1 can determine channel occupancy / status based on the energy level within the channel or the autocorrelation of signals within the channel, or it can determine channel occupancy by using a network allocation vector (NAV) timer.

[0080] After determining during DIFS that the channel is not being used by another device (i.e., the channel is idle) (and performing a backoff if necessary), station STA1 may send a Request to Transmit (RTS) frame to station STA2. Upon receiving the RTS frame, station STA2 may send a Allow to Transmit (CTS) frame in response to the RTS frame after SIFS. If dual CTS is enabled and station STA2 is an AP, the AP may send two CTS frames in response to the RTS frame (for example, the first CTS frame is in non-high throughput format and the second CTS frame is in HT format).

[0081] When station STA3 receives an RTS frame, it may use the time length information contained in the RTS frame to set its NAV timer for the transmission time of a later frame (e.g., SIFS + CTS frame time + SIFS + data frame time + SIFS + ACK frame time). When station STA3 receives a CTS frame, it may use the time length information contained in the CTS frame to set its NAV timer for the transmission time of a later frame. If a new frame is received before the NAV timer expires, station STA3 may update its NAV timer by using the time length information contained in the new frame. Station STA3 will not attempt to access the channel until the NAV timer expires.

[0082] If station STA1 receives a CTS frame from station STA2, it may send a data frame to station STA2 after the SIFS period has elapsed from the time the CTS frame was fully received. Upon successful receipt of the data frame, station STA2 may send an ACK frame as a response to the data frame after the SIFS period has elapsed.

[0083] If the NAV timer expires, the third station STA3 may use carrier sense to determine whether the channel is busy. If it determines that the channel is not being used by another device during the DIFS period after the NAV timer expires, station STA3 may, in accordance with the backoff process, attempt to access the channel after the conflict window has elapsed.

[0084] When Dual CTS is enabled, a station that has a Transmit Opportunity (TXOP) but has no data to transmit may shorten the TXOP by sending a CF-End frame. An AP that receives a CF-End frame with the AP's Basic Service Set Identifier (BSSID) as the destination address may respond by sending two more CF-End frames: a first CF-End frame using Space Time Block Coding (STBC) and a second CF-End frame without STBC. Upon receiving the CF-End frame, the station resets its NAV timer to 0 at the end of the PPDU containing the CF-End frame. Figure 5 shows that station STA2 sends an ACK frame to acknowledge the successful reception of the frame by the receiver.

[0085] With a clear demand for higher peak throughput / capacity in WLANs, a new working group was formed to create a revision of IEEE 802.11. This revision, called IEEE 802.11be (i.e., Extremely High Throughput (EHT)), was created to support improvements in the peak PHY speed of the corresponding WLAN. Considering IEEE 802.11b through 802.11ac, the peak PHY speed has increased by only 5 to 11 times, as shown in Figure 6, which presents Table 600 comparing various iterations of IEEE 802.11. In the case of IEEE 802.11ax, the 802.11ax working group focuses on improving efficiency rather than peak PHY speed in high-density environments. The maximum PHY speed (A Gbps) and PHY speed improvements (Bx) for IEEE 802.11be may depend on the maximum MCS (e.g., 4,096QAM and its coding rate).

[0086] IEEE 802.11be primarily focuses on the indoor and outdoor operation of WLANs at stationary and walking speeds in the 2.4, 5, and 6 GHz frequency bands. In addition to peak PHY speed, several candidate features are discussed. These candidate features include (1) more efficient use of 320 MHz bandwidth and discontinuous spectrum, (2) multiband / multichannel aggregation and operation, (3) 16 spatial stream and multiple input multiple output (MIMO) protocol improvements, (4) multi-access point (AP) coordination (e.g., co-transmit and joint transmit), (5) enhanced link adaptation and retransmission protocols (e.g., Hybrid Automatic Retransmission Request (HARQ)), and (6) adaptation to regulatory rules specific to the 6 GHz spectrum.

[0087] Some features, such as increased bandwidth and the number of spatial streams, have proven effective in previous projects focused on improving link throughput, and their feasibility has been demonstrated, making them achievable solutions.

[0088] Regarding the operating bandwidths of IEEE 802.11be (e.g., 2.4 / 5 / 6 GHz), the 6 GHz band (5.925–7.125 GHz) is considered for unlicensed use, making it highly likely that additional unlicensed spectrum above 1 GHz will be available. This would allow APs and STAs to become tri-band devices. Data transmissions greater than 160 MHz (e.g., 320 MHz) may be considered to improve the maximum PHY speed. For example, 320 MHz or 160+160 MHz data could be transmitted in the 6 GHz band. For example, 160+160 MHz data could be transmitted across the 5 GHz and 6 GHz bands.

[0089] In some embodiments, the transmitting STA generates a PPDU frame and sends it to the receiving STA. The receiving STA receives, detects, and processes the PPDU. The PPDU may be an EHT PPDU including legacy portions (e.g., legacy short training field (L-STF), legacy long training field (L-LTF), and legacy signal (L-SIG) field), EHT signal A field (EHT-SIG-A), EHT signal B field (EHT-SIG-B), EHT hybrid automatic repeat request field (EHT-HARQ), EHT short training field (EHT-STF), EHT long training field (EHT-LTF), and EHT-DATA field. Figure 7 includes Table 700 describing the fields of the EHT frame format. In particular, Table 700 describes the various fields that may be present within the PHY preamble, data fields, and midamble of the EHT frame format.For example, Table 700 includes the Legacy Short Training Field (L-STF) 712, Legacy Long Training Field (L-LTF) 714, Legacy Signal Field (L-SIG) 716, Repeated L-SIG (RL-SIG) 718, Universal Signal Field (U-SIG) 720, EHT Signal Field (EHT-SIG) 722, EHT Hybrid Auto Retransmission Request Field (EHT-HARQ) 724, EHT Short Training Field (EHT-STF) 726, EHT Long Training Field (EHT-LTF) 728, EHT Data Field 730, and EHT Midamble Field (EHT midamble This includes definitions 702 relating to one or more of field:EHT-MA)732, time length 704, discrete Fourier transform (DFT) period 706, guard interval (GI) 708, and subcarrier interval 710.

[0090] Due to the distributed nature of channel access networks such as IEEE 802.11 wireless networks, carrier sense mechanisms are crucial for collision-free operation. A physical carrier sense mechanism on one STA is responsible for detecting transmissions from other STAs. However, in some situations, detecting each individual case may be impossible. For example, an STA located at a long distance from another STA may assume its medium is idle and begin transmitting a frame while the other STA is also transmitting. Network allocation vectors (NAVs) can be used to overcome this hidden node. However, as wireless networks evolve to include simultaneous transmission / reception between multiple users within a single basic service set (BSS), such as cascaded uplink (UL) / downlink (DL) multi-user (MU) transmissions, mechanisms to enable such situations may be needed. As used herein, multi-user (MU) transmission refers to a case where multiple frames are transmitted simultaneously to or from multiple STAs using different resources. Examples of different resources include different frequency resources in OFDMA transmissions and different spatial streams in MU-MIMO transmissions. Therefore, DL-OFDMA, DL-MU-MIMO, UL-OFDMA, and UL-MU-MIMO are examples of MU transmission.

[0091] Wireless network systems may rely on retransmitting a Medium Access Control (MAC) protocol data unit (MPDU) if the transmitter (TX) has not received an acknowledgment from the receiver (RX), or if the MPDU has not been successfully decoded by the receiver. Using an Automatic Retransmission Request (ARQ) technique, the receiver discards the last failed MPDU before receiving the newly retransmitted MPDU. With the need for improved reliability and reduced latency, wireless network systems may evolve to a hybrid ARQ (HARQ) technique.

[0092] There are two methods for HARQ processing. In the first type of HARQ scheme, also known as chase combining (CC) HARQ (CC-HARQ), all subpackets to be retransmitted use the same puncturing pattern, so the retransmitted signal is the same as the previously failed signal. Puncture is necessary to remove some of the parity bits after encoding with error correction codes. The reason the same puncturing pattern is used in CC-HARQ is that it generates a data sequence coded using forward error correction (FEC), and the receiver uses maximum-ratio combining (MRC) to combine the received retransmitted bits with the same bits from the previous transmission. For example, an information sequence is transmitted in a packet of fixed length. Error correction and detection are performed throughout the packet at the receiver. However, the ARQ scheme can be inefficient when burst errors occur. To solve this more efficiently, subpackets are used. In subpacket transmission, only the subpacket containing the error needs to be retransmitted.

[0093] The receiver uses both the current and previously received subpackets to decode the data, so the probability of error in decoding decreases as the number of subpackets used increases. The decoding process terminates when it passes a cyclic redundancy check (CRC) and the entire packet has been decoded without errors or when the maximum number of subpackets has been reached. In particular, this scheme operates with a stop-and-wait protocol so that the receiver sends an acknowledgment (ACK) to the transmitter if it can decode the packet. If the transmitter successfully receives the ACK, it terminates the HARQ transmission of the packet. If the receiver cannot decode the packet, it sends a negative acknowledgment (NAK) to the transmitter, and the transmitter performs a retransmission process.

[0094] In the second type of HARQ scheme, also known as incremental redundancy (IR) HARQ (IR-HARQ), a different puncturing pattern is used for each subpacket so that the signal changes for each retransmitted subpacket compared to the original transmitted subpacket. IR-HARQ alternates between two puncturing patterns for odd-numbered and even-numbered transmissions. The redundancy of IR-HARQ improves the log likelihood ratio (LLR) of the parity bits to synthesize information sent across different transmissions due to a request, and reduces the coding rate as additional subpackets are used. As a result, the subpacket error rate is lower compared to CC-HARQ. The puncturing patterns used in IR-HARQ are indicated by a subpacket identity (SPID) directive. The SPID of the first subpacket may always be set to 0, and all systematic bits and punctured parity bits are transmitted in the first subpacket. Self-decoding is possible if the signal-to-noise ratio (SNR) environment on the receiving end is good (i.e., high SNR). In some embodiments, the subpackets to be transmitted, each with a corresponding SPID, are in increasing SPID order, but all but the first SPID are interchangeable / switchable.

[0095] To improve WLAN systems, AP cooperation is being discussed as a potential technology to be adopted in IEEE 802.11be, and there are various high-level classifications depending on the AP cooperation method. For example, there is a first type of cooperation method in which user-facing data is transmitted from a single AP (sometimes called "coordinated"), and a second type of cooperation method in which user-facing data is transmitted from multiple APs (sometimes called "joint").

[0096] In a cooperative system, multiple APs either 1) transmit on the same frequency resource based on cooperation, forming a spatial null to enable simultaneous transmission from multiple APs, or 2) transmit on orthogonal frequency resources by coordinating and dividing the spectrum, making more efficient use of the spectrum. In a joint system, multiple APs transmit jointly to a given user.

[0097] rTWT is one of the main features proposed in IEEE 802.11be to support low-latency transmission for various use cases such as augmented reality (AR) and virtual reality (VR). A limitation of the conventional rTWT scheme proposed in IEEE 802.11be is that scheduling information for rTWT SPs is shared by APs only with their associated STAs. In other words, the conventional rTWT scheme only notifies scheduling information for rTWT SPs within a single BSS. Therefore, members of an OBSS overlapping with a BSS may not be aware of the BSS's rTWT SPs, and thus may terminate the transmission of signals that interfere with signals transmitted by the BSS members during the rTWT SP, resulting in the rTWT SP not being fully protected. Consequently, BSS members may fail to take advantage of channel access opportunities during the rTWT SP due to interference caused by OBSS signals. This can result in further delays in the transmission of low-latency data within the BSS.

[0098] Figure 8 shows the limitations of the conventional rTWT method.

[0099] The figure shows a multi-BSS environment including AP1 associated with STA11 and STA12. AP1, STA11, and STA12 may belong to BSS1. The environment further includes AP2 associated with STA21. AP2 and STA21 may belong to BSS2. BSS1 and BSS2 may overlap in the sense that one or more members of BSS1 may hear signals from BSS2, and vice versa. In this situation, BSS2 may be considered as OBSS from the perspective of BSS1. Similarly, BSS1 may be considered as OBSS from the perspective of BSS2.

[0100] AP1 of BSS1 can transmit scheduling information for rTWT SPs to schedule rTWT SPs for BSS, during which time one or more members of BSS1 can transmit low-latency data. However, in the conventional rTWT scheme, scheduling information for rTWT SPs is not exchanged between AP1 and AP2, so AP2 (and other members of BSS2) may not be aware of the scheduled rTWT SPs of BSS1, and as a result, it may terminate the transmission of data to STA21 during the rTWT SP of BSS1. In this case, STA12, which is a member of the rTWT SP of BSS1 and is within the transmission range of AP2, may not be able to receive low-latency data during the rTWT SP of BSS1 due to interference from AP2's signal. Therefore, in this example, STA12 is considered a "victim" of OBSS interference. In the example shown in the figure, STA21 and AP2 are located toward the edge of the coverage area of ​​BSS1, so they cannot hear some of the signals of BSS1, and thus may incorrectly identify a channel as idle when it is not. This could result in STA21 or AP2 transmitting data during the rTWT SP of BSS1, thereby causing interference. The problem can be exacerbated if STA21 or AP2 is outside the coverage area of ​​BSS1.

[0101] This disclosure introduces an extended rTWT scheme that may help avoid OBSS interference between BSS rTWT SPs in high-density multi-BSS scenarios. The extended rTWT scheme may schedule new types of rTWT SPs in which members of BSS and members of OBSS can transmit data without collision. Three types of rTWT SPs are described herein: 1) A first type of rTWT SP allows members of OBSS to transmit data between BSS rTWT SPs when they have low-latency data to transmit; 2) A second type of rTWT SP allows members of OBSS to compete for channels between BSS rTWT SPs after certain conditions (e.g., the channel is idle for a predetermined period) have been met; 3) A third type of rTWT SP allows members of BSS and OBSS to transmit simultaneously between rTWT SPs by having members of BSS transmit data using a primary channel and members of OBSS transmit data using a secondary channel.

[0102] To implement the extended rTWT scheme, a new rTWT parameter set may be defined. The new rTWT parameter set may be referred to as the extended rTWT parameter set (or e-rTWT parameter set). The e-rTWT parameter set may include one or more parameters from the conventional rTWT parameter set (e.g., the rTWT parameter set proposed in IEEE 802.11be) and one or more new parameters to support one or more of the new types of rTWT SPs described above.

[0103] Figure 9 shows an extended rTWT parameter set notified by a single AP in several embodiments.

[0104] In the example shown in the figure, AP1 may transmit a beacon frame 900 containing an e-rTWT parameter set for scheduling an rTWT SP for BSS1. BSS1 is considered to be the rTWT holder in this scenario. The e-rTWT parameter set may include parameters that describe the scheduled rTWT SP. For example, the e-rTWT parameters may include one or more parameters from the conventional rTWT parameter set (e.g., target wake time, nominal minimum TWT wake time length, TWT wake interval mantissa, TWT wake interval exponent, and / or broadcast TWT persistence as defined in the IEEE 802.11 wireless networking standard), and one or more new parameters to support the extended rTWT scheme. The rTWT holder BSS is the main BSS that controls the rTWT operation (e.g., the BSS of the AP that acquires the TXOP before the rTWT operation is performed and / or the BSS of the AP that initiates negotiation / exchange of the e-rTWT parameter set with the OBSS AP). All members of BSS1 and BSS2 receiving beacon frame 900 are restricted by the e-rTWT parameter set, meaning they must adhere to the rTWT SP described by the e-rTWT parameter set (for example, an STA should terminate any transmissions before the start of an rTWT SP, and an STA should only transmit data during an rTWT SP if those transmissions are permitted). While a conventional rTWT parameter set restricts only members of a single BSS, the e-rTWT parameter set can restrict members of more than one BSS. In this example, AP2 and STA21 of BSS2 are within AP1's coverage area, so they receive beacon frame 900 (including the e-rTWT parameter set contained within it) and are therefore restricted by the e-rTWT parameter set. The diagram shows that the e-rTWT parameter set is included in a beacon frame, but it should be understood that the e-rTWT parameter set may also be included in other types of frames.For example, the e-RTWT parameter set may be included in the probe response frame or control frame.

[0105] All APs and STAs shown in the diagram are restricted by the e-rTWT parameter set, so all of them can terminate any transmission before the start of the rTWT SP. During the rTWT SP, AP1 may send a trigger frame 905 requesting an uplink transmission from STA12. In response to receiving the trigger frame 905, STA12 may send a data frame 910 to AP1. In response to receiving the data frame 910, AP1 may send an acknowledgment (ACK) frame 915 to STA12. In this example, members of BSS2 protect BSS1 transmissions by not transmitting data during the rTWT SP.

[0106] By notifying both members of BSS1 and BSS2 of the e-rTWT parameter set, and by restricting those members by the e-rTWT parameter set, the rTWT SP of BSS1 can be protected from interference from the BSS2 signal.

[0107] Figure 10 shows both the AP for BSS and the AP for OBSS indicating an extended rTWT parameter set in several embodiments.

[0108] In the example shown in the figure, AP1 may transmit a beacon frame 1000 containing the e-rTWT parameter set. AP2 may transmit a beacon frame 1005 containing the same e-rTWT parameter set. The e-rTWT parameter set may include parameters to describe the scheduled rTWT SP, as described with reference to Figure 9 above. BSS1 is considered to be the rTWT holder in this scenario. In the example shown in the figure, AP1 and AP2 transmit their beacon frames successively (one after the other), but in other embodiments, AP1 and AP2 may transmit their beacon frames simultaneously. All members of BSS1 receiving beacon frame 1000 may be restricted by the e-rTWT parameter set contained in beacon frame 1000. Similarly, all members of BSS2 receiving beacon frame 1005 may be restricted by the e-rTWT parameter set contained in beacon frame 1005. In this example, since the e-rTWT parameter sets contained in beacon frame 1000 and beacon frame 1005 are identical, all members of BSS1 and BSS2 are restricted by the same e-rTWT parameter set. In one embodiment, AP1 and AP2 may negotiate the e-rTWT parameter set (for example, by communicating directly with each other or through an intermediary), or otherwise agree on the same e-rTWT parameter set before transmitting beacon frames (so that both of them notify the same e-rTWT parameter set).

[0109] Since all BSS1 and BSS2 members are restricted by the e-rTWT parameter set, all of them can terminate any transmission before the start of the rTWT SP. During the rTWT SP, AP1 may send a trigger frame 1015 requesting an uplink transmission from STA12. In response to receiving the trigger frame 1015, STA12 may send a data frame 1020 to AP1. In response to receiving the data frame 1020, AP1 may send an ACK frame 1025 to STA12. In this example, the BSS2 members protect the BSS1 transmission by not transmitting data during the rTWT SP.

[0110] By notifying both members of BSS1 and BSS2 of the same e-rTWT parameter set, and by restricting those members by the e-rTWT parameter set, the rTWT SP of BSS1 can be protected from interference from the BSS2 signal.

[0111] Therefore, the e-rTWT parameter set can restrict members of multiple BSSs. The e-rTWT parameter set can be notified by a single AP (e.g., shown in Figure 9) or by multiple APs (e.g., shown in Figure 10). Generally, multiple APs notifying the e-rTWT parameter set allows more STAs to be restricted by the e-rTWT parameter set, thereby better protecting the rTWT SP. For brevity, an example with a single OBSS is described. However, it should be understood that the techniques and concepts described herein can be extended to situations with more than one OBSS.

[0112] The e-rTWT parameter set can be used for scheduling rTWT SPs for a BSS while the BSS is given the opportunity to send data to overlapping OBSS members. Three such types of rTWT SPs are described herein. The parameters included in the e-rTWT parameter set may differ depending on the type of rTWT SP being scheduled.

[0113] Figure 11 shows a frame exchange sequence for a first type of rTWT SP according to several embodiments.

[0114] The first type of rTWT SP may allow a member of the OBSS to transmit data during the BSS's rTWT SP when the OBSS member has low-latency data to transmit.

[0115] As shown in the figure, AP1 of BSS1 may transmit a beacon frame 1100 containing an e-rTWT parameter set for scheduling rTWT SPs. The e-rTWT parameter set may include parameters that enable members of BSS2 to transmit low-latency data between rTWT SPs of BSS1. For example, the e-rTWT parameter set may include information about sections of rTWT SPs of BSS1 to which members of BSS1 can transmit data, and information about different sections of rTWT SPs of BSS1 to which members of BSS2 can transmit data. BSS1 is the rTWT holder in this scenario, and the rTWT SPs are assumed to be for BSS1. BSS2 is therefore assumed to be the OBSS in this scenario. In the examples shown in the figure and some of the following figures, the e-rTWT parameter set is advertised by a single AP (AP1). In other embodiments, as described above, it should be understood that the e-rTWT parameter set may be advertised by multiple APs (e.g., by AP1 and AP2).

[0116] In one embodiment, the e-rTWT parameter set further includes parameters for providing information about one or more of the following: an identifier for a restricted target waketime service period; operating bandwidth for a first section of the restricted target waketime service period; operating bandwidth for a second section of the restricted target waketime service period; received signal strength indicator (RSSI) for APs of BSS; RSSI for APs of OBSS (e.g., RSSI may be used for cooperative space reuse purposes); traffic identifier (TID) of traffic that may be transmitted during the first section of the restricted target waketime service period; TID of traffic that may be transmitted during the second section of the restricted target waketime service period; stream classification service identifier of streams that may be transmitted during the first section of the restricted target waketime service period; and stream classification service identifier of streams that may be transmitted during the second section of the restricted target waketime service period.

[0117] All members of BSS1 and BSS2 that receive beacon frame 1100 may terminate any TXOP or transmission before the initiation of the rTWT SP.

[0118] During the rTWT SP, AP1 may send a trigger frame 1105 requesting uplink transmission of BSS1 from STA12. In response to receiving the trigger frame 1105, STA12 may send a data frame 1010 to AP1. In response to receiving the data frame 1010, AP1 may send an ACK frame 1115 to STA12.

[0119] In this example, it is assumed that immediately after the transmission of ACK frame 1115, STA21 of BSS2 determines that it has low-latency data to send to AP2. STA21 may send a low-latency data frame 1120 (containing the low-latency data) to AP2 during the rTWT SP of BSS1 (for example, during a specific section of the rTWT SP allocated for OBSS transmission, as indicated by the e-rTWT parameter set notified in beacon frame 1100). In response to receiving the low-latency data frame 1120, AP2 may send an ACK frame 1125 to STA21. In one embodiment, if AP1 determines that BSS2 does not have low-latency data to send during the determined period, AP1 may resume frame exchange earlier than the trigger frame 1130.

[0120] Next, AP1 may send another trigger frame 1130 requesting uplink transmission from STA12. In response to receiving trigger frame 1130, STA12 may send data frame 1135 to AP1. In response to receiving data frame 1135, AP1 may send ACK frame 1140 to STA12.

[0121] In this example, it is assumed that there exists a protocol that allows low-latency BSS2 data to be transmitted between rTWT SPs without colliding with BSS1 data.

[0122] In one embodiment, AP1 and AP2 negotiate the e-rTWT parameter set before it is notified. AP1 and AP2 may negotiate the e-rTWT parameter set so that the rTWT SP can be shared by BSS1 and BSS2. In one embodiment, the rTWT SP is configured to include a first section from which one or more members of BSS1 who are not members of BSS2 can transmit data, and a second section from which one or more members of BSS2 who are not members of BSS1 can transmit data. Since AP1 and AP2 can cooperate to share the rTWT SP, the rTWT SP can be considered a “cooperative rTWT SP”.

[0123] Therefore, members of OBSS (e.g., BSS2) may be able to transmit low-latency data during the rTWP SP of a BSS (e.g., BSS1), thereby reducing the delay of OBSS low-latency data. Additionally, members of OBSS are restricted by the e-rTWT parameter set (e.g., thereby terminating any transmissions before the start of the BSS's rTWT SP), thereby avoiding collisions.

[0124] Figure 12 shows a frame exchange sequence for a second type of rTWT SP according to some embodiments.

[0125] A second type of rTWT SP may allow the STA of the OBSS to compete for the channel during the rTWT SP of the BSS after certain conditions (e.g., the channel has been idle for a given period) have been met.

[0126] As shown in the figure, AP1 may transmit a beacon frame 1200 containing an e-rTWT parameter set. The e-rTWT parameter set may include parameters that allow a member of BSS2 to transmit low-latency data between the rTWT SPs of BSS1 when the channel is idle for a predetermined period. For example, the e-rTWT parameter set may include information about the length of the predetermined period (however, in some embodiments, the length of the period is hardcoded in the radio networking standard). BSS1 is the rTWT holder in this scenario, and the rTWT SP is considered to be for BSS1. Thus, BSS2 is considered to be the OBSS in this scenario.

[0127] All members of BSS1 and BSS2 that receive beacon frame 1200 may terminate any TXOP or transmission before the rTWT SP begins.

[0128] During the rTWT SP, AP1 may send a trigger frame 1205 requesting uplink transmission from STA12. In response to receiving trigger frame 1205, STA12 may send data frame 1210 to AP1. In response to receiving data frame 1210, AP1 may send ACK frame 1215 to STA12.

[0129] In this example, it is assumed that STA21 of BSS2 determines that it has low-latency data to send to AP2 during the rTWT SP. STA21 may compete for channel access during the rTWT SP of BSS1 if it determines (for example, based on performing a clear channel assessment (CCA)) that the channel is idle for a given period (e.g., not sensing any Wi-Fi signals). A channel can be idle for several reasons. For example, a channel may be idle because AP1's transmission ends early due to the channel having good channel quality. In this example, it is assumed that the channel is idle for a given period, thereby allowing STA21 to send a low-latency data frame 1220 (containing the low-latency data) following the backoff period. In response to receiving the low-latency data frame 1220, AP2 may send an ACK frame 1225 to STA21.

[0130] In one embodiment, the length of the predetermined period is set as follows: length of predetermined period = aSIFSTime + AIFS[AC], where aSIFSTime is the length of the short interframe space (SIFS) and AIFS[AC] is the length of the arbitration interframe space for a specific access category AC. The access category may be an existing access category used in the IEEE 802.11 wireless networking standard, or it may be a newly defined access category to support low-latency traffic. In one embodiment, AP1 and AP2 negotiate the length of the predetermined period before the e-rTWT parameter set is announced.

[0131] Next, AP1 may send another trigger frame 1230 during the rTWT SP to request an uplink transmission from STA12 (for example, to request the transmission of aperiodic low-latency data). STA12 may send a data frame 1235 to AP1. In response to receiving data frame 1235, AP1 may send an ACK frame 1240 to STA12.

[0132] Therefore, members of OBSS (e.g., BSS2) may compete for a channel to transmit low-latency data during a BSS (e.g., BSS1) rTWP SP, provided certain conditions are met that reduce the delay of OBSS low-latency data (e.g., the channel is idle for a predetermined period). Furthermore, members of OBSS are restricted by an e-rTWT parameter set to avoid collisions (e.g., they terminate any transmissions before the start of a BSS rTWT SP and wait until the channel is idle for a predetermined period before transmitting data during the rTWT SP).

[0133] Figure 13 shows a frame exchange sequence for a third type of rTWT SP according to several embodiments.

[0134] A third type of rTWT SP may enable BSS members and OBSS members to simultaneously transmit data during the rTWT SP, with BSS members transmitting data using the primary channel and OBSS members transmitting data using the secondary channel.

[0135] As shown in the figure, AP1 may transmit a beacon frame 1300 containing an e-rTWT parameter set. The e-rTWT parameter set may include parameters that enable a member of BSS2 to transmit low-latency data between rTWT SPs of BSS1 using a secondary channel. For example, the e-rTWT parameter set may include channel allocation information indicating that BSS2 will use a secondary / non-primary channel to transmit data between rTWT SPs. BSS1 is considered to be the rTWT holder in this scenario, and the rTWT SP is for BSS1. Therefore, BSS2 is considered to be the OBSS in this scenario.

[0136] The channel status in BSS1 and BSS2 may differ. For example, assuming that a primary 80MHz channel (meaning "P80" in the figure) and a secondary 80MHz channel (meaning "S80" in the figure) are available, the secondary 80MHz channel may be busy in BSS1 but idle in BSS2. Therefore, in one embodiment, BSS1 and BSS2 may divide the channels in the frequency domain so that BSS1 uses the primary 80MHz channel during rTWT SP and BSS2 uses the secondary 80MHz channel during rTWT SP, thereby avoiding interference in a multi-BSS scenario. Information regarding channel allocation may be included in the beacon frame 1300 as part of the e-rTWT parameter set. Channel allocation between BSS1 and BSS2 may be predetermined or negotiated between AP1 and AP2 (e.g., via a beacon frame or management frame) prior to notification of the e-rTWT parameter set.

[0137] All members of BSS1 and BSS2 that receive beacon frame 1300 may terminate any TXOP or transmission before the initiation of the rTWT SP.

[0138] During the rTWT SP, AP1 may transmit a trigger frame 1305 on the primary 80MHz channel (P80) requesting uplink transmission from STA12. In response to receiving the trigger frame 1305, STA12 may transmit a data frame 1310 to AP1 on the primary 80MHz channel. In response to receiving the data frame 1310, AP1 may transmit an ACK frame 1215 to STA12 on the primary 80MHz channel.

[0139] Next, AP1 may transmit another trigger frame 1320 on the primary 80MHz channel requesting an uplink transmission from STA12. In response to receiving trigger frame 1320, STA12 may transmit data frame 1325 to AP1 on the primary 80MHz channel. In this example, it is assumed that before STA12 transmits data frame 1325, STA21 of BSS2 determines that it has low-latency data to transmit to AP2. STA21 may transmit a low-latency data frame 1330 (containing the low-latency data) to AP2 on the secondary 80MHz channel simultaneously with AP12's transmission of data frame 1325 on the primary 80MHz channel. Thus, data frame 1325 and low-latency data frame 1330 can be transmitted simultaneously during the rTWT SP without interference.

[0140] In response to receiving data frame 1325, AP1 may transmit ACK frame 1335 on the primary 80MHz channel. In response to receiving low-latency data frame 1330, AP2 may transmit ACK frame 1340 on the secondary 80MHz channel at the same time as AP1 transmits ACK frame 1335. Therefore, ACK frames 1335 and ACK frame 1340 can also be transmitted simultaneously during rTWT SP without interference.

[0141] In one embodiment, both AP1 and AP2 are aware of which channel is the primary channel. The operating bandwidth of AP1 and AP2 may include the primary channel. AP1 may notify the e-rTWT parameter set on the primary channel in order to schedule the rTWT SP. AP2 may receive the e-rTWT parameter set and thereby be able to recognize when the rTWT SP will start and end. Before the rTWT SP starts, AP2 may transmit data using the primary channel. However, after the rTWT SP has started, AP2 may switch to transmitting data outside of AP1's operating bandwidth (e.g., using a secondary / non-primary channel) to avoid interference. When the rTWT SP ends, AP2 may switch back to transmitting data using the primary channel.

[0142] Figure 14 shows channel splitting according to several embodiments.

[0143] As shown in the figure, the frequency domain may include a primary 20MHz channel, a secondary 20MHz channel, and a secondary 40MHz channel. Prior to the IEEE 802.11be wireless networking standard, STAs were not permitted to use secondary channels if the primary channel was busy. However, in newer / future wireless networking standards, it is expected that secondary channels, which allow for more efficient use of the spectrum, may be used even if the primary channel is busy. Therefore, an OBSS STA may use secondary channels to transmit data between the BSS's rTWT SPs to avoid interference. For example, as shown in the figure, the operating bandwidth (OPBW) of the rTWT holder may include only the primary 20MHz channel. In this case, the OBSS may transmit data between the BSS's rTWT SPs using the secondary 20MHz channel and / or the secondary 40MHz channel. As another example, as shown in the figure, the operating bandwidth of the rTWT holder may include only the primary 20MHz channel and the secondary 20MHz channel (or primary 40MHz channel). In this case, OBSS may transmit data using a secondary 40MHz channel during the rTWT SP of BSS.

[0144] Referring here to Figure 15, according to an exemplary embodiment, method 1500 is described as scheduling an rTWT SP. Method 1500 may be performed by an AP of the BSS (e.g., AP1 shown in Figure 8). The AP may be implemented by one or more devices described herein, such as wireless device 104.

[0145] In addition, although shown in a specific order, in some embodiments the operations of Method 1500 (and other methods shown in other figures) may be performed in a different order. For example, although the operations of Method 1500 are shown in a sequential order, some operations may be performed in overlapping periods, either partially or entirely.

[0146] In one embodiment, during operation 1505, the AP negotiates with the AP of the overlapping BSS that overlaps with the BSS regarding the characteristics of the limited target waketime service period.

[0147] Operation 1510 may be performed to schedule a first type of limited target waketime service period. In operation 1510, the AP transmits a frame containing scheduling information for a restricted target waketime service period, where the restricted target waketime service period includes a first section on which one or more BSS members can transmit data, and a second section on which one or more OBSS members that overlap with the BSS but are not members of the BSS can transmit data (without overlapping in time with the first section). In one embodiment, the scheduling information for the restricted target waketime service period includes information about when the first section of the restricted target waketime service period occurs, and information about when the second section of the restricted target waketime service period occurs. In one embodiment, the OBSS AP transmits a second frame containing the same restricted target waketime service period scheduling information contained in the frame transmitted by the BSS AP. In one embodiment, the frame is a beacon frame. In one embodiment, the frame is a probe response frame or a management frame. In one embodiment, the BSS members and OBSS members receiving the frame terminate any transmissions before the start of the restricted target waketime service period.

[0148] Operation 1515 may be performed to schedule a second type of restricted target waketime service period. In operation 1510, the AP sends a frame containing restricted target waketime service period scheduling information for scheduling a restricted target waketime service period for the BSS, where the OBSS member can transmit data during the BSS restricted target waketime service period after determining that the channel is idle for a predetermined period. In one embodiment, the restricted target waketime service period scheduling information includes information about the length of the predetermined period. In one embodiment, the OBSS AP sends a second frame containing the same restricted target waketime service period scheduling information contained in the frame sent by the BSS AP. In one embodiment, the frame is a beacon frame. In one embodiment, the frame is a probe response frame or a management frame. In one embodiment, the BSS member and the OBSS member receiving the frame terminate any transmissions before the start of the restricted target waketime service period.

[0149] Operation 1520 may be performed to schedule a third type of restricted target waketime service period. In operation 1520, the AP sends a frame containing restricted target waketime service period scheduling information for scheduling restricted target waketime service periods for BSSs, where one or more members of BSSs may transmit data during the restricted target waketime service period of the BSS using the primary channel, and where one or more members of OBSSs may transmit data during the restricted target waketime service period of the BSS using the secondary channel. Transmissions by BSS members and transmissions by OBSS members may occur concurrently. In one embodiment, the restricted target waketime service period scheduling information includes channel assignments for the primary channel and / or secondary channel.

[0150] In one embodiment, the scheduling information for the restricted target waketime service period (in addition to the information described above) further includes information about one or more of the following: an identifier for the restricted target waketime service period, operating bandwidth for the first section of the restricted target waketime service period, operating bandwidth for the second section of the restricted target waketime service period, received signal strength indicators (RSSI) for the APs of the BSS, RSSIs for the APs of the OBSS (for example, RSSIs may be used for cooperative space reuse purposes), traffic identifiers (TIDs) of traffic that may be transmitted during the first section of the restricted target waketime service period, TIDs of traffic that may be transmitted during the second section of the restricted target waketime service period, stream classification service identifiers of streams that may be transmitted during the first section of the restricted target waketime service period, and stream classification service identifiers of streams that may be transmitted during the second section of the restricted target waketime service period.

[0151] Referring here to Figure 16, according to an exemplary embodiment, method 1600 is described for transmitting data during a first type of rTWT SP. Method 1600 may be performed by an STA of an OBSS (e.g., STA21 shown in Figure 8) that overlaps with the BSS. The STA may be implemented by one or more devices described herein, such as the wireless device 104.

[0152] In operation 1605, the STA receives a frame from the AP containing scheduling information for a restricted target waketime service period, where the restricted target waketime service period includes a first section on which one or more members of the BSS can transmit data, and a second section on which one or more members of the OBSS that are not members of the BSS can transmit data. In one embodiment, the scheduling information for the restricted target waketime service period includes information about when the first section of the restricted target waketime service period occurs, and information about when the second section of the restricted target waketime service period occurs. In one embodiment, the AP is an AP of the BSS (an AP belonging to a different BSS than the STA). In one embodiment, the AP is an AP of the OBSS (an AP belonging to the same BSS as the STA).

[0153] In one embodiment, the STA determines when the restricted target waketime service period occurs based on the scheduling information for the restricted target waketime service period, and terminates any transmissions before the start of the restricted target waketime service period.

[0154] In one embodiment, in operation 1610, the STA determines when the first section of the restricted target waketime service period occurs, based on the scheduling information of the restricted target waketime service period.

[0155] In operation 1615, the STA determines when the second section of the restricted target waketime service period occurs, based on the scheduling information for the restricted target waketime service period.

[0156] In one embodiment, operation 1620 refrains from transmitting during the first section of the restricted target waketime service period.

[0157] In operation 1625, the STA sends a data frame during the second section of the limited target waketime service period.

[0158] Referring here to Figure 17, according to an exemplary embodiment, method 1700 is described for transmitting data during a second type of rTWT SP. Method 1700 may be performed by an STA of an OBSS (e.g., STA21 shown in Figure 8) that overlaps with the BSS. The STA may be implemented by one or more devices described herein, such as the wireless device 104.

[0159] In operation 1705, the STA receives a frame from the AP containing scheduling information for the restricted target waketime service period for scheduling the restricted target waketime service period for the BSS. In one embodiment, the AP is the AP of the BSS (an AP belonging to a different BSS than the STA). In one embodiment, the AP is the AP of the OBSS (an AP belonging to the same BSS as the STA).

[0160] In operation 1710, the STA performs channel sensing of the channel during the limited target waketime service period.

[0161] In operation 1715, the STA determines whether the channel was idle for a predetermined period. If the channel was not idle for the predetermined period, the flow proceeds to operation 1710, during which the STA continues to perform channel sensing. Otherwise, if the channel was idle for the predetermined period, the flow proceeds to operation 1720. In one embodiment, the scheduling information for the limited target waketime service period includes information about the length of the predetermined period.

[0162] In operation 1720, the STA transmits data frames during the BSS's limited target waketime service period.

[0163] Referring here to Figure 18, according to an exemplary embodiment, method 1800 is described for transmitting data during a third type of rTWT SP. Method 1800 may be performed by an STA of OBSS overlapping with BSS (e.g., STA21 shown in Figure 8). The STA is implemented by one or more devices described herein, such as wireless device 104.

[0164] In operation 1805, the STA receives a frame from the AP containing scheduling information for a limited target waketime service period for scheduling a limited target waketime service period for the BSS. In one embodiment, the AP is an AP of the BSS (an AP belonging to a different BSS than the STA). In one embodiment, the AP is an AP of the OBSS (an AP belonging to the same BSS as the STA).

[0165] In operation 1810, the STA determines, based on the scheduling information for the restricted target waketime service period, that the secondary channel will be used for transmission during the restricted target waketime service period of the BSS. In one embodiment, the scheduling information for the restricted target waketime service period includes channel allocation information relating to the allocation of the primary channel and / or secondary channel.

[0166] In operation 1815, the STA transmits data frames using the secondary channel during the BSS's limited target waketime service period, where one or more STAs of the BSS transmit data using the primary channel during the BSS's limited target waketime service period.

[0167] In operation 1820, in response to the determination that the limited target waketime service period has ended, the STA switches to using the primary channel for transmission.

[0168] While many of the solutions and techniques provided herein are described with reference to WLAN systems, it should be understood that these solutions and techniques are also applicable to other network environments such as cellular telecommunications networks and wired networks. In some embodiments, the solutions and techniques provided herein are, or may be embodied within, a manufactured product in which a non-temporary machine-readable medium (such as microelectronic memory) stores instructions thereon for programming one or more data processing components (collectively referred to here as “processors” or “processing units”) to perform the operations described herein. In other embodiments, some of these operations may be performed by specific hardware components, including hardwired logic (e.g., dedicated digital filter blocks and state machines). Alternatively, these operations may be performed by any combination of programmed data processing components and fixed hardwired circuit components.

[0169] In some cases, an embodiment may be a device (e.g., APSTA, non-APSTA, or another network or computing device) comprising one or more hardware and software logic structures for performing one or more of the operations described herein. For example, as described herein, the device may include a memory unit storing instructions that can be executed by a hardware processor installed in the device. The device may also include one or more other hardware or software elements, such as a network interface or a display device.

[0170] Some parts of the detailed explanation above are presented in terms of algorithms and symbolic representations of operations on data bits in computer memory. The multiple descriptions and representations of these algorithms are multiple forms used by those skilled in the art in multiple data processing fields to most efficiently convey the essence of these functions to others skilled in the art. Here, and in general, an algorithm is considered to be a consistent set of actions that produce a desired result. Multiple operations require multiple physical operations on multiple physical quantities. These quantities usually, though not always, take the form of electrical or magnetic signals that can be stored, combined, compared, and otherwise manipulated. These signals are sometimes conveniently referred to as bits, values, elements, symbols, characters, terms, or numbers, primarily because it is convention.

[0171] However, it should be kept in mind that all of these and similar terms will be associated with appropriate physical quantities and are merely convenient labels applied to those quantities. This disclosure may refer to actions and processes of computer systems or other similar electronic computing devices that manipulate data represented as physical (electronic) quantities in the registers and memory of the computer system and convert them into other data similarly represented as physical quantities in the memory or registers of the computer system or other such information storage systems.

[0172] This disclosure also relates to an apparatus for performing the operations described herein. This apparatus may be constructed specifically for the intended purpose, or it may include a general-purpose computer that is selectively invoked or reconfigured by a computer program stored in the computer. For example, a computer system or other data processing system may perform the computer implementation methods described herein in response to its processor executing a computer program (e.g., a set of instructions) contained in memory or other non-temporary machine-readable storage medium. Such computer programs may be stored in computer-readable storage media, each coupled to a computer system bus, such as any type of disk including floppy disks, optical disks, CD-ROMs, and magneto-optical disks, read-only memory (ROM), random access memory (RAM), EPROM, EEPROM, magnetic or optical cards, or any type of medium suitable for storing electronic instructions.

[0173] The algorithms and representations presented herein are not inherently related to any particular computer or other device. Various general-purpose systems may be used with the programs taught herein, or it may be proven that it is more convenient to construct more specialized devices to implement the methods. The structures of these various systems will appear as described below. In addition, this disclosure is not described with reference to any particular programming language. It will be understood that various programming languages ​​may be used to implement the teachings of this disclosure as described herein.

[0174] This disclosure may be provided as a computer program product or software that may include a machine-readable medium storing instructions, and by using such instructions, a computer system (or other electronic device) may be programmed to perform the processes described herein. The machine-readable medium includes any mechanism for storing information in a format readable by a machine (e.g., a computer). In some embodiments, the machine-readable (e.g., computer-readable) medium includes machine (e.g., computer)-readable storage media such as read-only memory ("ROM"), random-access memory ("RAM"), magnetic disk storage media, optical storage media, flash memory components, etc.

[0175] In the above-described specification, embodiments of the Disclosure have been described with reference to specific exemplary embodiments. It will be apparent that various modifications can be made to these embodiments without departing from the broader spirit and scope of the embodiments of the Disclosure described in the following claims. Accordingly, this specification and the drawings should be considered illustrative, not restrictive.

Claims

1. A method performed by a wireless device implementing an access point (AP) of a basic service set (BSS) in a wireless network, wherein the method is: A step of sending a frame having scheduling information for a restricted target waketime service period, for scheduling a restricted target waketime service period, which includes a first section where one or more members of a BSS may transmit data, and a second section where one or more members of overlapping BSSs (OBSSs) that overlap with the BSS but are not members of the BSS may transmit data. A method for providing this.

2. The method according to claim 1, wherein the scheduling information for the restricted target waketime service period includes information regarding when the first section of the restricted target waketime service period occurs, and information regarding when the second section of the restricted target waketime service period occurs.

3. The scheduling information for the aforementioned limited target waketime service period is: The method of claim 2, further comprising information relating to one or more of the identifier of the restricted target waketime service period, the operating bandwidth for the first section of the restricted target waketime service period, the operating bandwidth for the second section of the restricted target waketime service period, the received signal strength indicator (RSSI) for the AP of the BSS, the RSSI for the AP of the OBSS, the traffic identifier (TID) of traffic that may be transmitted during the first section of the restricted target waketime service period, the TID of traffic that may be transmitted during the second section of the restricted target waketime service period, the stream classification service identifier of a stream that may be transmitted during the first section of the restricted target waketime service period, and the stream classification service identifier of a stream that may be transmitted during the second section of the restricted target waketime service period.

4. The stage of negotiating the AP of the aforementioned OBSS with the characteristics of the limited target waketime service period. The method according to claim 1, further comprising:

5. The method according to claim 4, wherein the AP of the OBSS transmits a second frame containing scheduling information for the same limited target waketime service period included in the frame transmitted by the AP of the BSS.

6. The method according to claim 1, wherein the frame is a beacon frame.

7. The method according to claim 1, wherein the frame is a probe response frame or a management frame.

8. The method according to claim 1, wherein the members of the BSS and the OBSS that receive the frame terminate any transmission before the restricted target waketime service period begins.

9. A method performed by a wireless device implementing a station (STA) of an overlapping basic service set (OBSS) that overlaps with a basic service set (BSS) in a wireless network, wherein the method is: The step of receiving a frame from an access point (AP) containing scheduling information for a restricted target waketime service period, wherein the restricted target waketime service period includes a first section on which one or more members of the BSS may transmit data, and a second section on which one or more members of the OBSS who are not members of the BSS may transmit data; A step of determining when the second section of the restricted target waketime service period occurs, based on the scheduling information of the restricted target waketime service period; and The step of transmitting a data frame during the second section of the limited target waketime service period. A method for providing this.

10. A step of determining when the first section of the restricted target wake time service period occurs, based on the scheduling information of the restricted target wake time service period; and The stage of refraining from transmission during the first section of the aforementioned limited target waketime service period. The method according to claim 9, further comprising:

11. The method according to claim 9, wherein the AP is the AP of the BSS.

12. The method according to claim 9, wherein the AP is the AP of the OBSS.

13. A step of determining when the restricted target wake time service period occurs based on the scheduling information of the restricted target wake time service period; and The stage in which any transmissions are terminated before the aforementioned limited target waketime service period begins. The method according to claim 9, further comprising:

14. A wireless device that operates in a wireless network, wherein the wireless device is Radio frequency transceiver; A memory device for storing instruction sets; and A processor connected to the memory device, wherein the instruction set, when executed by the processor, causes the wireless device to perform a step of any one of claims 1 to 8. A wireless device equipped with the following features.

15. A wireless device that operates in a wireless network, wherein the wireless device is Radio frequency transceiver; A memory device for storing instruction sets; and A processor connected to the memory device, wherein the instruction set, when executed by the processor, causes the wireless device to perform a step of any one of claims 9 to 13. A wireless device equipped with the following features.

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