WO2025226488A1 - Padding technique to prevent collisions during dynamic bandwidth signaling - Google Patents

Abstract

Disclosed herein is a method performed by an access point (AP) to prevent collisions during dynamic bandwidth signaling. The method includes generating an initial control frame, determining a minimum padding length to add to an end of the initial control frame based on a transmission duration of the initial control frame, and transmitting the initial control frame with padding having at least the minimum padding length to the STA to cause the STA to switch from operating in a first mode to operating in a second mode, wherein the STA uses a wider bandwidth when the STA operates in the second mode compared to when the STA operates in the first mode

Description

PADDING TECHNIQUE TO PREVENT COLLISIONS DURING DYNAMIC

BANDWIDTH SIGNALING

CROSS-REFERENCE TO RELATED APPLICATION

[0001] This application claims the benefit of U.S. Provisional Application No. 63/637,218, filed April 22, 2024, titled “Method of padding for wide bandwidth access of power saving devices”, which is hereby incorporated by reference.

TECHNICAL FIELD

[0002] The present disclosure generally relates to wireless communications, and more specifically, relates to a padding technique to prevent collisions during dynamic bandwidth signaling.

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. l lbe will introduce 4096-QAM (Quadrature Amplitude Modulation), enabling higher data rates by encoding more bits per symbol. The standard will also feature improved medium access control (MAC) efficiency, enhanced power saving capabilities, and better support for high-density environments. With these advancements, 802.1 Ibe is expected to deliver theoretical maximum data rates of up to 46 gigabits per second (Gbps), making it suitable for bandwidth-intensive applications such as virtual and augmented reality, 8K video streaming, and high-performance gaming. The IEEE 802.1 Ibe standard is projected to be finalized by the end of 2024, paving the way for the next generation of Wi-Fi devices and networks.

[0005] To save power, a station (STA) may operate in a low power listen mode in which the STA only activates the components that are needed to receive frames using a minimum bandwidth (e.g., 20 MHz bandwidth). An access point (AP) may transmit an initial control frame (e.g., a request-to-send (RTS) frame) to the STA using the minimum bandwidth to cause the STA to use a wider bandwidth (e.g., 80 MHz bandwidth). Responsive to receiving the initial control frame, the STA may activate components (e.g., radio frequency (RF) chain component and baseband component) that are needed to use the wider bandwidth and transmit an initial control response frame (e.g., a clear-to-send (CTS) frame) to the AP using the wider bandwidth. That is, the STA may switch from operating in the low power listen mode to operating in a wider bandwidth mode in response to receiving the initial control frame. Such technique of changing the bandwidth used by a STA on demand may be referred to as dynamic bandwidth signaling. The initial control frame may be a frame that is transmitted to initiate dynamic bandwidth signaling or otherwise initiate the use of a wider bandwidth. The initial control response frame may be a frame that is transmitted as a response to the initial control frame.

[0006] Typically, the channel conditions surrounding the AP and STA are different. Thus, in existing wireless networking standards, when the STA attempts to respond to the initial control frame using the wider bandwidth (e.g., when transmitting the CTS frame), it should consider the channel transmission status of neighboring STAs. For example, the STA should ensure that the wider bandwidth channel has been idle for at least a point coordination function interframe space (PIFS) interval before the STA received the initial control frame to ensure that collisions do not occur at neighboring STAs of the STA. However, a STA operating in low power listen mode can only listen to the minimum bandwidth so the STA cannot determine whether the wider bandwidth channel has been idle for at least a PIFS interval before the STA received the initial control frame. Thus, the STA cannot ensure that the PIFS idleness requirement has been observed. This may result in collisions occurring at neighboring STAs of the STA during dynamic bandwidth signaling.

BRIEF DESCRIPTION OF THE DRAWINGS

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

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

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

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

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

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

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

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

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

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

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

[0018] Figure 10 is a diagram showing an access point (AP) transmitting a frame to a station (STA) to cause the STA to switch operation modes, according to some embodiments.

[0019] Figure 11 is a diagram showing a wireless network topology in which the padding technique can be applied, according to some embodiments.

[0020] Figure 12 is a diagram showing dynamic bandwidth signaling operations when the PIFS idleness requirement is observed, according to some embodiments.

[0021] Figure 13 is a diagram showing the occurrence of a frame collision due to the point coordination function interframe space (PIFS) idleness requirement not being observed, according to some embodiments.

[0022] Figure 14 is a diagram showing a situation where collisions are avoided during dynamic bandwidth signaling by adding sufficient padding to the initial control frame, according to some embodiments.

[0023] Figure 15 is a diagram showing a format of a common info field, according to some embodiments.

[0024] Figure 16 is a diagram showing a format of a user info field, according to some embodiments.

[0025] Figure 17 is a diagram showing a format of a user info field of a multi-user request-to- send transmission opportunity sharing (MU-RTS TXS) frame, according to some embodiments.

[0026] Figure 18 is a diagram showing a scrambling sequence encoding, according to some embodiments.

[0027] Figure 19 is a diagram showing the length of padding that needs to be added to an initial control frame to prevent collisions from occurring in the worst case scenario, according to some embodiments.

[0028] Figure 20 is a diagram showing equations for determining the minimum padding duration, according to some embodiments.

[0029] Figure 21 is a diagram showing the durations of different types of acknowledgement (ACK) frames for different transmission rates, according to some embodiments.

[0030] Figure 22 is a diagram showing the durations of different types of initial control frames for different transmission rates, according to some embodiments.

[0031] Figure 23 is a diagram showing the minimum padding lengths to add to an initial control frame depending on the transmission rate of the initial control frame and the acknowledgement (ACK) frame type when the transmission rate of the ACK frame is 6 Megabits per second (Mbps), according to some embodiments.

[0032] Figure 24 is a diagram showing the minimum padding lengths to add to an initial control frame depending on the transmission rate of the initial control frame and the ACK frame type when the transmission rate of the ACK frame is 12 Mbps, according to some embodiments. [0033] Figure 25 is a diagram showing the minimum padding lengths to add to an initial control frame depending on the transmission rate of the initial control frame and the ACK frame type when the transmission rate of the ACK frame is 24 Mbps, according to some embodiments. [0034] Figure 26 is a flow diagram of a method for preventing collisions during dynamic bandwidth signaling, according to some embodiments.

DETAILED DESCRIPTION

[0035] The present disclosure generally relates to wireless communications, and more specifically, relates to a padding technique to prevent collisions during wider bandwidth access. [0036] As mentioned above, a station (STA) operating in a low power listen mode that receives an initial control frame for dynamic bandwidth signaling cannot ensure that the point coordination function interframe space (PIFS) idleness requirement has been observed in the wider bandwidth channel before the initial control frame was received, which may result in collisions occurring at neighboring STAs.

[0037] The present disclosure introduces a way to prevent collisions from occurring when performing dynamic bandwidth signaling. This is achieved by considering the fundamental reason for performing the PIFS idleness check before receiving an initial control frame. The reason for performing the PIFS idleness check is to prevent collisions from occurring when the STA receiving the initial control frame transmits an initial control response frame as a response to the initial control frame (e.g., if the PIFS idleness requirement is not observed, the initial control response frame may collide with transmissions by neighboring STAs).

[0038] A padding technique is described herein that adds padding to the initial control frame to prevent collisions from occurring at neighboring STAs of the STA receiving the initial control frame without having to check for PIFS idleness. The padding technique may help protect/ensure the frame exchange sequence between neighboring STAs of the STA receiving the initial control frame, which can improve the overall channel utilization and spectral efficiency of the wireless network.

[0039] According to some embodiments, an AP generates an initial control frame, determines a minimum padding length to add to an end of the initial control frame based on a transmission duration of the initial control frame, and transmits the initial control frame with padding having at least the minimum padding length to a STA to cause the STA to switch from operating in a first mode to operating in a second mode, wherein the STA uses a wider bandwidth when the STA operates in the second mode compared to when the STA operates in the first mode. The minimum padding length may be determined as a function of the transmission duration of the initial control frame and the transmission duration of an ACK frame in an overlapping basic service set (OBSS) with respect to the AP. The transmission duration of the initial control frame may be a function of the size of the initial control frame and the transmission rate of the initial control frame. The transmission duration of the ACK frame in the OBSS may be a function of the size of the ACK frame and the transmission rate of the ACK frame. In general, it is shown by the present disclosure that the minimum padding length that needs to be added to the initial control frame increases as the transmission duration of the initial frame decreases and the transmission duration of the ACK frame increases.

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

[0041] 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.

[0042] Figure 1 shows a wireless local area network (WLAN) 100 with a basic service set (BSS) 102 that includes a plurality of wireless devices 104 (sometimes referred to as WLAN devices 104). Each of the wireless devices 104 may include a medium access control (MAC) layer and a physical (PHY) layer according to an IEEE (Institute of Electrical and Electronics Engineers) standard 802.11, including one or more of the amendments

(e.g., 802.1 la/b/g/n/p/ac/ax/bd/be). In one embodiment, the MAC layer of a wireless device 104 may initiate transmission of a frame to another wireless device 104 by passing a PHY- TXSTART. request (TXVECTOR) to the PHY layer. The TXVECTOR provides parameters for generating and/or transmitting a corresponding frame. Similarly, a PHY layer of a receiving wireless device may generate an RXVECTOR, which includes parameters of a received frame and is passed to a MAC layer for processing. [0043] 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).

[0044] 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.

[0045] The baseband processor 210 performs baseband signal processing and includes a MAC processor 212 and a PHY processor 222. The baseband processor 210 may utilize 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.

[0046] 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.

[0047] The PHY processor 222 includes a transmitting (TX) signal processing unit (SPU) 224 and a receiving (RX) SPU 226. The PHY processor 222 implements a plurality of functions of the PHY layer. These functions may be performed in software, hardware, or a combination thereof according to an implementation. [0048] 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.

[0049] The RF transceiver 240 includes an RF transmitter 242 and an RF receiver 244. The RF transceiver 240 is configured to transmit first information received from the baseband processor 210 to the WLAN 100 (e.g., to another WLAN device 104 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.

[0050] The antenna unit 250 includes one or more antennas. When Multiple-Input Multiple- Output (MIMO) or Multi-User MIMO (MU-MIMO) is used, the antenna unit 250 may include 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.

[0051] 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.

[0052] As described herein, many functions of the WLAN device 104 may be implemented in either hardware or software. Which functions are implemented in software and which functions are implemented in hardware will 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.

[0053] As described herein, a wide variety of electronic devices, circuits, firmware, software, and combinations thereof may be used to implement the functions of the components of the WLAN device 104. Furthermore, the WLAN device 104 may include other components, such as application processors, storage interfaces, clock generator circuits, power supply circuits, and the like, which have been omitted in the interest of brevity.

[0054] 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.

[0055] The TxSP 324 includes an encoder 300, an interleaver 302, a mapper 304, an inverse Fourier transformer (IFT) 306, and a guard interval (GI) inserter 308.

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

[0057] 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.

[0058] 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.

[0059] 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.

[0060] 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.

[0061] 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. [0062] 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.

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

[0064] 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.

[0065] 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.

[0066] 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.

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

[0068] The RF receiver 344 receives an RF signal via 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.

[0069] 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.

[0070] When the received transmission is the MIMO or MU-MIMO transmission, the RxSP 326 may include a spatial demapper for converting the respective outputs of the FTs 316 of the receiver chains to constellation points of a plurality of space-time streams, and an STBC decoder for despreading the constellation points from the space-time streams into one or more spatial streams. [0071] The demapper 314 demaps the constellation points output from the FT 316 or the STBC decoder to bit streams. If the received transmission was encoded using LDPC encoding, the demapper 314 may further perform LDPC tone demapping before performing the constellation demapping.

[0072] 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.

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

[0074] 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.

[0075] 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. [0076] 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.

[0077] The PHY entity for IEEE 802.11 is based on Orthogonal Frequency Division Multiplexing (OFDM) or Orthogonal Frequency Division Multiple Access (OFDMA). In either OFDM or OFDMA Physical (PHY) layers, a STA (e.g., a wireless device 104) is capable of transmitting and receiving Physical Layer (PHY) Protocol Data Units (PPDUs) (also referred to as PLCP (Physical Layer Convergence Procedure) Protocol Data Units) that are compliant with the mandatory PHY specifications. A PHY specification defines a set of Modulation and Coding Schemes (MCS) and a maximum number of spatial streams. Some PHY entities define downlink (DL) and uplink (UL) Multi-User (MU) transmissions having a maximum number of space-time streams (STS) per user and employing up to a predetermined total number of STSs. A PHY entity may provide support for 10 Megahertz (MHz), 20 MHz, 40 MHz, 80 MHz, 160 MHz, 240 MHz, and 320 MHz contiguous channel widths and support for an 80+80, 80+160 MHz, and 160+160 MHz non-contiguous channel width. Each channel includes a plurality of subcarriers, which may also be referred to as tones. A PHY entity may define signaling fields denoted as Legacy Signal (L-SIG), Signal A (SIG-A), and Signal B (SIG-B), and the like within a PPDU by which some necessary information about PHY Service Data Unit (PSDU) attributes are communicated. The descriptions below, for sake of completeness and brevity, refer to OFDM-based 802.11 technology. Unless otherwise indicated, a station refers to a non-AP STA. [0078] 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.

[0079] 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.

[0080] 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.

[0081] 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.

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

[0083] 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.

[0084] 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.

[0085] 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.

[0086] 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.

[0087] 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.

[0088] After determining that the channel is not used by other devices (that is, that the channel is IDLE) during a DIFS (and performing backoff if required), the station STA1 may transmit a Request-To-Send (RTS) frame to the station STA2. Upon receiving the RTS frame, after a SIFS the station STA2 may transmit a Clear-To-Send (CTS) frame as a response to the RTS frame. If Dual-CTS is enabled and the station STA2 is an AP, the AP may send two CTS frames in response to the RTS frame (e.g., a first CTS frame in a non-High Throughput format and a second CTS frame in the HT format). [0089] 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.

[0090] 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.

[0091] 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. [0092] 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.

[0093] The IEEE 802.1 Ibn (Ultra High Reliability, UHR) working group has been established to address the growing demand for higher peak throughput and reliability in Wi-Fi. As shown in Figure 6, the peak PHY rate has significantly increased from IEEE 802.1 lb to IEEE 802.1 Ibe (Wi-Fi 7), with the latter focusing on further improving peak throughput. The UHR study group aims to enhance the tail of the latency distribution and jitter to support applications that require low latency, such as video-over- WLAN, gaming, AR, and VR. It is noted that various characteristics of UHR (e g., max PHY rate, PHY rate enhancement, bandwidth/number of spatial streams, and operating bands) are still to be determined. [0094] The focus of IEEE 802.1 Ibe is primarily on WLAN indoor and outdoor operation with stationary and pedestrian speeds in the 2.4, 5, and 6 GHz frequency bands. In addition to peak PHY rate, different candidate features are under discussion. These candidate features include (1) a 320MHz bandwidth and a more efficient utilization of a non-contiguous spectrum, (2) multi -band/multi-channel aggregation and operation, (3) 16 spatial streams and Multiple Input Multiple Output (MIMO) protocol enhancements, (4) multi-Access Point (AP) Coordination (e.g., coordinated and joint transmission), (5) an enhanced link adaptation and retransmission protocol (e.g., Hybrid Automatic Repeat Request (HARQ)), and (6) adaptation to regulatory rules specific to a 6 GHz spectrum.

[0095] 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.

[0096] 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.

[0097] 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 160MHz data transmissions (e.g., 320 MHz or 640 MHz) could be considered to increase the maximum PHY rate. For example, 320 MHz or 160+160MHz data could be transmitted in the 6 GHz band. For example, 160+160 MHz data could be transmitted across the 5 and 6 GHz bands.

[0098] 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.

[0099] The Extremely High Throughput (EHT) PPDU frame encompasses several components. It includes a legacy part, which comprises fields such as the Legacy Short Training Field (L-STF), Legacy Long Training Field (L-LTF), Legacy Signal Field (L-SIG), and Repeated Legacy Signal Field (RL-SIG). These fields are used to maintain compatibility with older Wi-Fi standards. [00100] In addition to the legacy part, the EHT PPDU frame also contains the Universal Signal Field (U-SIG), EHT Signal Field (EHT-SIG), EHT Short Training Field (EHT-STF), and EHT Long Training Field (EHT-LTF). These fields are specific to the EHT standard and are used for various purposes, such as signaling, synchronization, and channel estimation.

[00101] Figure 7 provides a more detailed description of each field in the EHT PPDU frame, including their purposes and characteristics.

[00102] Regarding the Ultra High Reliability (UHR) PPDU, its frame structure is currently undefined and will be determined through further discussions within the relevant working group or study group. This indicates that the specifics of the UHR PPDU are still under development and will be finalized based on the outcomes of future deliberations.

[00103] The distributed nature of channel access networks, such as IEEE 802.11 WLANs, makes the carrier sense mechanism useful for ensuring collision-free operation. Each station (STA) uses its physical carrier sense to detect transmissions from other STAs. However, in certain situations, it may not be possible for a STA to detect every transmission. For instance, when one STA is located far away from another STA, it might perceive the medium as idle and start transmitting a frame, leading to collisions. To mitigate this hidden node problem, the network allocation vector (NAV) has been introduced.

[00104] As the IEEE 802.11 standard continues to evolve, it now includes scenarios where multiple users can simultaneously transmit or receive data within a basic service set (BSS), such as uplink (UL) and downlink (DL) multi-user (MU) transmissions in a cascaded manner. In these cases, the existing carrier sense and NAV mechanisms may not be sufficient, and modifications or newly defined mechanisms may be required to facilitate efficient and collision- free operation.

[00105] For the purpose of this disclosure, MU transmission refers to situations where multiple frames are transmitted to or from multiple STAs simultaneously using different resources. Examples of these resources include different frequency resources in Orthogonal Frequency Division Multiple Access (OFDMA) transmission and different spatial streams in Multi-User Multiple Input Multiple Output (MU-MIMO) transmission. Consequently, downlink OFDMA (DL-OFDMA), downlink MU-MIMO (DL-MU-MIMO), uplink OFDMA (UL- OFDMA), uplink MU-MIMO (UL-MU-MIMO), and OFDMA with MU-MIMO are all considered examples of MU transmission.

[00106] Figure 8 illustrates an example of multi-user (MU) transmission in Orthogonal Frequency-Division Multiple Access (OFDMA), in accordance with some embodiments of the present disclosure. [00107] In the IEEE 802.1 lax and 802.1 Ibe specifications, the trigger frame plays a useful role in facilitating uplink multi-user (MU) transmissions. The purpose of the trigger frame is to allocate resources and solicit one or more Trigger-based (TB) Physical Layer Protocol Data Unit (PPDU) transmissions from the associated stations (STAs).

[00108] 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.

[00109] Figure 9 illustrates an example scenario where an access point (AP) operating in an 80MHz bandwidth environment sends a Trigger frame to multiple associated STAs. Upon receiving the Trigger frame, the STAs respond by sending their respective Uplink Orthogonal Frequency Division Multiple Access (UL OFDMA) TB PPDUs, utilizing the allocated resources within the specified 80 MHz bandwidth.

[00110] After successfully receiving the UL OFDMA TB PPDUs, the AP acknowledges the STAs by sending an acknowledgement frame. This acknowledgement can be in the form of an 80MHz width multi-STA Block Acknowledgement (Block Ack) or a Block Acknowledgement with a Direct Feedback (DF) OFDMA method. The multi-STA Block Ack allows the AP to acknowledge multiple STAs simultaneously, while the Block Ack with DF OFDMA enables the AP to provide feedback to the STAs using the same OFDMA technique employed in the uplink transmission.

[00111] The trigger frame is a useful component in enabling efficient uplink MU transmissions in IEEE 802.1 lax and 802.1 Ibe networks, by allocating resources and coordinating the uplink transmissions from multiple STAs within the same bandwidth.

[00112] Wireless network systems can rely on retransmission of media access control (MAC) protocol data units (MPDUs) when the transmitter (TX) does not receive an acknowledgement from the receiver (RX) or MPDUs are not successfully decoded by the receiver. Using an automatic repeat request (ARQ) approach, the receiver discards the last failed MPDU before receiving the newly retransmitted MPDU. With requirements of enhanced reliability and reduced latency, the wireless network system can evolve toward a hybrid ARQ (HARQ) approach.

[00113] 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.

[00114] 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.

[00115] 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.

[00116] AP coordination has been considered as a potential technology to improve WLAN system throughput in the IEEE 802.1 Ibe standard and is still being discussed in the IEEE 802.1 Ibn (UHR) standard. To support various AP coordination schemes, such as coordinated beamforming, OFDMA, TDMA, spatial reuse, and joint transmission, a predefined mechanism for APs is necessary.

[00117] In the context of coordinated TDMA (C-TDMA), the AP that obtains a transmit opportunity (TXOP) is referred to as the sharing AP. This AP initiates the AP coordination schemes to determine the AP candidate set by sending a frame, such as a Beacon frame or probe response frame, which includes information about the AP coordination scheme capabilities. The AP that participates in the AP coordination schemes after receiving the frame from the sharing AP is called the shared AP. The sharing AP is also known as the master AP or coordinating AP, while the shared AP is referred to as the slave AP or coordinated AP.

[00118] The operation of various AP coordination schemes has been discussed in the IEEE 802.1 Ibe and UHR standards:

[00119] Coordinated Beamforming (C-BF): Multiple APs transmit on the same frequency resource by coordinating and forming spatial nulls, allowing for simultaneous transmission from multiple APs.

[00120] Coordinated OFDMA (C-OFDMA): APs transmit on orthogonal frequency resources by coordinating and splitting the spectrum, enabling more efficient spectrum utilization.

[00121] Joint Transmission (JTX): Multiple APs transmit jointly to a given user simultaneously by sharing data between the APs.

[00122] Coordinated Spatial Reuse (C-SR): Multiple APs or STAs adjust their transmit power to reduce interference between APs.

[00123] By implementing these AP coordination schemes, WLAN systems can improve their overall throughput and efficiency by leveraging the cooperation between multiple APs.

[00124] To save power, a STA may operate in a low power listen mode in which the STA only activates the components that are needed to receive frames using the minimum bandwidth. The STA may only activate the components that are needed to use a wider bandwidth when the STA needs to transmit or receive data. For example, a STA may only listen to a 20 Megahertz (MHz) bandwidth when operating in the low power listen mode to be able to receive legacy control frames and only use the STA’s full bandwidth when there is a need for data transmission or reception. This may allow the wireless device to significantly reduce its power consumption. Such technique of changing the bandwidth used by a STA on demand (e.g., to save power) may be referred to as dynamic bandwidth signaling.

[00125] An AP may initiate dynamic bandwidth signaling by transmitting an initial control frame to a STA operating in low power listen mode to cause the STA to operate in a wider bandwidth mode. The initial control frame may include dynamic bandwidth signaling information to define and control the behavior the STA after the STA receives the initial control frame. The initial control frame may be a trigger frame such as a MU-RTS frame, a multi-user block acknowledgement request (MU-BAR) frame, or a buffer status report poll (BSRP) frame. If a frame capable of channel reservation such as a RTS frame or MU-RTS frame is used as the initial control frame, the initial control frame can be used for performing wide bandwidth channel reservation and mode switching at the same time. The STA may respond to the initial control frame by transmitting an initial control response frame. The initial control response frame may be a CTS frame or a multi-station block acknowledgement (BA) frame.

[00126] A STA inevitably incurs a mode switching delay when switching operation modes from a low power listen mode to a wider bandwidth mode. A STA that receives an initial control frame should only activate the components (e.g., RF chain component and baseband component) needed for using a wider bandwidth after completing reception of the initial control frame, including performing a frame check sequence (FCS) check. The mode switching delay should be taken into consideration when transmitting the initial control frame. One approach to account for the mode switching delay is to add padding to the initial control frame to provide the STA with additional time to switch modes. When such padding is added to the initial control frame, the STA may start to use the wider bandwidth as soon as the STA completes reception of the initial control frame.

[00127] When a STA operating in a low power listen mode receives an initial control frame, it is not able to determine the channel state of the wider bandwidth channel before the initial control frame was received. This is because the STA is not able to listen to the wider bandwidth channel when the STA operates in the low power listen mode (e.g., so it cannot perform a physical clear channel assessment (CCA) or virtual carrier sensing in the wider bandwidth channel). If an AP transmits a (MU-)RTS frame to the STA in a wider bandwidth channel having a bandwidth that is wider than the 20 MHz minimum bandwidth (e.g., a 80 MHz bandwidth), the STA may not be able to accurately determine the appropriate channel width for response because the STA is not able to receive transmissions outside of the minimum 20 MHz bandwidth. As a result, neither the AP nor the STA are able to accurately perform channel reservation for surrounding APs/STAs, thereby reducing the likelihood of a successful frame exchange sequence in the wide bandwidth channel.

[00128] When switching operation modes to use a wider bandwidth, it is important to ensure that the STA receiving the initial control frame has adequate time to switch to using the wider bandwidth. This can be done by adding padding to the initial control frame, as mentioned earlier. Also, it is important to assess the channel state of the wider bandwidth channel by performing a clear channel assessment (CCA).

[00129] In addition to considering padding for the mode transition delay and performing CCA for the wider bandwidth channel, another important aspect to consider for dynamic bandwidth signaling is to check that the wider bandwidth channel has been idle for at least a PIFS interval before the initial control frame is received. Typically, the channel conditions surrounding the transmitter (e.g., AP) and the receiver (e.g., STA) can be different. As such, in legacy IEEE 802.11 wireless networking standards, when the receiver intends to attempt wide bandwidth channel access by receiving and responding to a control frame such as a RTS frame, it considers the channel transmission status of neighboring STAs. Factors to consider when responding to the requested channel width include the bandwidth of the channel in which the initial control frame was received and whether the channel has been idle for at least a PIFS interval prior to receiving the initial control frame. Checking for such PIFS idleness ensures that the frame exchange sequence between the RTS transmitter and hidden STAs are not corrupted. [00130] However, a STA operating in a low power listen mode that receives an initial control frame for dynamic bandwidth signaling cannot ensure that this PIFS idleness requirement has been observed in the wider bandwidth channel before the initial control frame was received, which can result in collisions occurring at neighboring STAs of the STA receiving the initial control frame. The present disclosure introduces a way to enable wide bandwidth channel access through dynamic bandwidth signaling in a manner that prevents collisions by considering the fundamental reason for performing the PIFS idleness check before receiving an initial control frame. In particular, a padding technique is described herein that adds padding to the initial control frame to prevent collisions from occurring at neighboring STAs of the STA receiving the initial control frame without having to check for PIFS idleness. The padding technique may help protect/ensure the frame exchange sequence between neighboring STAs of the STA receiving the initial control frame (without having to check for PIFS idleness), which can improve the overall channel utilization and spectral efficiency of the wireless network.

[00131] Also, to support dynamic bandwidth signaling for achieving wider bandwidth channel access, the present disclosure proposes using a MU-RTS frame for a single user for dynamic bandwidth signaling. Existing IEEE 802.11 wireless networking standards do not permit using a MU-RTS frame for dynamic bandwidth signaling. This is because if a MU-RTS frame is used for dynamic bandwidth signaling, multiple STAs may respond to the MU-RTS frame with CTS frames using dynamic bandwidths, in which case, the AP (that transmitted the MU-RTS frame) may not be able to determine which STAs transmitted a CTS frame. However, the present disclosure recognizes that a MU-RTS frame can be used for dynamic bandwidth signaling if it is addressed to a single user/STA.

[00132] Figure 10 is a diagram showing an AP transmitting a frame to a STA to cause the STA to switch operation modes, according to some embodiments.

[00133] The AP and the STA may be capable of operating in an 80 MHz bandwidth. The 80 MHz bandwidth may include a primary 20 MHz channel (P20), a secondary 20 MHz channel (S20), a primary 40 MHz channel (which may be a combination of P20 and S20), and a secondary 40 MHz channel (S40). The STA may be a power save (PS) STA that initially operates in a 20 MHz operation mode to save power. The 20 MHz operation mode may be a low power listen mode. The AP may transmit RTS frames or MU-RTS frames to the STA using the full 80 MHz bandwidth to cause the STA to switch operation modes to the 80 MHz operation mode. Upon receiving a (MU-)RTS frame from the AP in P20 and recognizing that the (MU-)RTS frame is addressed to itself, the STA may switch operation modes to the 80 MHz operation mode (e.g., by activating an RF chain component and a baseband component). Thus, the STA may normally stay in the 20 MHz operation mode to save power and only switch operation modes to the 80 MHz operation mode (or other wider bandwidth operation mode) when needed.

[00134] Once the STA has switched operation modes to the 80 MHz operation mode, the STA may perform carrier sensing and transmit clear-to-send (CTS) frames to the AP in the idle channels of the full 80 MHz bandwidth after a short interframe space (SIFS) interval after receiving the RTS frame in P20. In this example, the channels are organized in units of 20 MHz and frames are transmitted in the non-HT PPDU format in the 20 MHz channels. After receiving the CTS frames, the AP and the STA may perform a frame exchange sequence using the full 80 MHz bandwidth for a transmission opportunity (TXOP) duration. After the TXOP duration is over, the STA may switch operation modes back to the 20 MHz operation mode to save power. In this example, the (MU-)RTS frame functions as an initial control frame and the CTS frame functions as an initial control response frame.

[00135] As mentioned above, a STA operating in a low power listen mode cannot ascertain the status of channels that are outside the minimum bandwidth (e.g., 20 MHz bandwidth). As such, the STA is not aware of the usage of other channels before receiving the initial control frame and thus cannot perform a PIFS idleness check, which can result in collisions occurring at neighboring STAs of the STA. However, as will be described in additional detail herein, an appropriate length of padding may be added to the initial control frame to prevent collisions from occurring at neighboring STAs of the STA receiving the initial control frame without having to perform a PIFS idleness check. A STA operating in the low power listen mode that receives such an initial control frame (that includes the padding described herein) may perform an uplink multi-user carrier sensing (UL MU CS) for the requested wider bandwidth channel upon receiving the initial control frame (e.g., during a SIFS interval after receiving the initial control frame). If the wider bandwidth channel is idle, the STA may transmit an initial control response frame in the wider bandwidth channel after a SIFS interval after receiving the initial control frame. If sufficient padding is added to the initial control frame, the frame exchange sequences of neighboring STAs of the STA receiving the initial control frame can be protected by the STA performing a SIFS interval idleness check after receiving the initial control frame (without the STA having to perform a PIFS idleness check before the initial control frame was received).

[00136] Figure 11 is a diagram showing a wireless network topology in which the padding technique can be applied, according to some embodiments.

[00137] As shown in the diagram, the wireless network includes a first AP (“API”), a second AP (“AP2”), a first STA (“STA1”), a second STA (“STA2”), and a third STA (“STA3”). Various embodiments are described herein in the context of the wireless network topology shown in Figure 11 with the following assumptions. API may operate a first basic service set (“BSS1”) having an operating bandwidth of 80 MHz. AP2 may operate a second BSS (“BSS2”) having an operating bandwidth of 40 MHz. The operating bandwidth of BSS 1 may encompass the entire operating bandwidth of BSS2. Also, BSS1 and BSS2 may use different primary 20 MHz channels. API and AP2 may be hidden nodes to each other. Also, STA2 may be a hidden node to API. STA1 may be associated with API (belongs to BSS1) and may overhear transmissions by AP2. STA2 and STA3 may be associated with AP2 (belong to BSS2). STA2 may overhear transmissions by AP2 but not transmissions by API . STA3 may overhear transmissions by STA1, API, and AP2.

[00138] Figure 12 is a diagram showing dynamic bandwidth signaling operations when the PIFS idleness requirement is observed, according to some embodiments.

[00139] As shown in the diagram, at time t3, API may transmit (MU-)RTS frames to STA1 using the full 80 MHz operating bandwidth. Upon receiving a (MU-)RTS frame from API in its primary 20 MHz channel, STA1 may switch operation modes from a 20 MHz operation mode to a 80 MHz operation mode, perform UL MU CS in the full 80 MHz bandwidth, and transmit CTS frames to API using the full 80 MHz operating bandwidth after a SIFS interval after receiving the (MU-)RTS frame. Prior to this, at time tO, AP2 may have transmitted a 40 MHz PPDU to STA2 using its full 40 MHz operating bandwidth. If the 40 MHz PPDU (transmitted by AP2) and the (MU-)RTS frames (transmitted by API) have a timing gap that is at least as long as a PIFS interval (the difference between t3 and tl is equal to or longer than a PIFS interval duration), the acknowledgement (ACK) frames transmitted by STA2 at t3 (for acknowledging the 40 MHz PPDU) and the CTS frames transmitted by STA1 will not collide (e.g., at AP2). As a result, even if the intended recipient of the ACK frames (e.g., AP2) is within the transmission range of the CTS frames (i.e., within the transmission range of STA1), the intended recipient of the ACK frames will be able to receive the ACK frames without corruption, preventing network inefficiencies due to retransmissions. Also, any STAs that are within the transmission range of STA1 may be able to correctly receive the CTS frames for proper RTS/CTS-based protection operations. Thus, to implement dynamic bandwidth signaling for wider bandwidth channel access without collisions, it is recognized by the present disclosure that there should be a sufficient timing gap between frames transmitted by APs/STAs hidden to the transmitter of the initial control frame and the initial control frame itself (e.g., (MU-)RTS frames). Otherwise, collisions can occur, as shown in the example shown in Figure 13. [00140] Figure 13 is a diagram showing the occurrence of a frame collision due to the PIFS idleness requirement not being observed, according to some embodiments.

[00141] The situation shown in the diagram is similar to the situation shown in Figure 12 but the PIFS idleness requirement is not observed. As shown in the diagram, if the PIFS idleness requirement is not observed (e.g., the difference between t3 and t2 is shorter than a PIFS interval duration), frame collisions may occur. For example, as shown in the diagram, at time t5, STA1 (which is a power save (PS) STA) may transmit CTS frames to API using the full 80 MHz operating bandwidth as a response to the (MU-)RTS frames, which may collide at AP2 with the ACK frames transmitted by STA2 in STA2’s primary 20 MHz channel and secondary 20 MHz channel, resulting in AP2 not being able to properly receive the ACK frames and also not being able to properly set its basic NAV. Due to this, AP2 may need to retransmit the 40 MHz PPDU, which can be a waste of network resources. Also, any other STAs that overhear the ACK frames and the CTS frames (e.g., AP2 and potentially other APs/STAs) may not be able to properly set their NAVs due to the collision.

[00142] To address such a situation, the present disclosure introduces a way to prevent collisions between transmissions by the recipient of the initial control frame (e.g., STA1) and hidden STAs (e.g., STA2) from occurring when performing dynamic channel signaling by adding an appropriate length of padding to the initial control frame. [00143] Figure 14 is a diagram showing a situation where collisions are avoided during dynamic bandwidth signaling by adding sufficient padding to the initial control frame, according to some embodiments.

[00144] As shown in the diagram, at time tO, AP2 may transmit a 40 MHz PPDU to STA2 using its full 40 MHz operating bandwidth, which is outside of STAl’s primary 20 MHz channel. Responsive to receiving the 40 MHz PPDU, STA2 may transmit ACK frames to AP2 using its full 40 MHz operating bandwidth after a SIFS interval after receiving the 40 MHz PPDU from AP2. Also, at time t3, API may transmit (MU-)RTS frames with padding to STA1 using its full 80 MHz operating bandwidth. Responsive to receiving a (MU-)RTS frame in its primary 20 MHz channel, STA1 may switch operation modes from a 20 MHz operation mode to a 80 MHz operation mode and transmit CTS frames to API using its full 80 MHz bandwidth after a SIFS interval after receiving the (MU-)RTS frame.

[00145] In the example shown in the diagram, the time gap between the end of 40 MHz PPDU and the start of (MU-)RTS frames (the difference between t3 and t2) is shorter than a PIFS interval duration (which is the difference between t3 and tl). However, due to the padding added to the (MU-)RTS frames, a collision between the ACK frames (transmitted by STA2) and CTS frames (transmitted by STA1) is avoided. Thus, if sufficient padding is added to the (MU- )RTS frames, STA1 may dynamically use a wider bandwidth (e.g., 80 MHz bandwidth) while avoiding collisions and without needing to perform a PIFS idleness check.

[00146] In an embodiment, a MU-RTS frame for a single user is used as the initial control frame for dynamic bandwidth signaling. It is noted that this is not permitted by existing IEEE 802.11 wireless networking standards. In the existing IEEE 802.11 wireless networking standards, RTS and CTS frames are used for dynamic bandwidth signaling. The information related to dynamic bandwidth signaling may be provided using the scrambler seed in the service field of the data field. In an embodiment, the MU-RTS frame for a single user can specify the receiving STA and indicate the bandwidth that the receiving STA should use, thereby providing dynamic bandwidth signaling information. For example, a user information (or “user info”) field of the MU-RTS frame or a common information (or “common info”) field of the MU-RTS frame may be used for this purpose. The service field of the CTS frame may remain the same as in the existing wireless networking standards, containing dynamic bandwidth signaling information.

[00147] Figure 15 is a diagram showing a format of a common info field, according to some embodiments. The common info field shown in the diagram is an EHT variant common info field. [00148] As shown in the diagram, the common info field may include a trigger type field 1502 (4 bits), a UL length field 1504 (12 bits), a more TF field 1506 (1 bit), a CS required field 1508 (1 bit), a UL BW field 1510 (2 bits), a GI and HE EHT-LTF type/triggered TXOP sharing mode field 1512 (2 bits) a reserved field 1514 (1 bit), a number of HE/EHT-LTF symbols field 1516 (3 bits), a reserved field 1518 (1 bit), a LDPC extra symbol segment field 1520 (1 bit), an AP transmission (Tx) power field 1522 (6 bits), a pre-FED padding factor field 1524 (2 bits), a PE disambiguity field 1526 (1 bit), a UL spatial reuse field 1528 (16 bits), a reserved field 1530 (1 bit), a HE/EHT P160 field 1532 (1 bit), a special user info field flag field 1534 (1 bit), an EHT reserved field 1536 (7 bits), a reserved field 1538 (1 bit), and a trigger dependent common info field 1540 (variable length). The bit positions of the fields may be as shown in the diagram. [00149] In an embodiment, one or more of the reserved fields included in the common info field (e.g., reserved field 1514, reserved field 1518, reserved field 1530, and/or reserved field 1530) may be used for carrying dynamic bandwidth signaling information. The other fields can be interpreted according to IEEE 802.11 wireless networking standards (e.g., EHT). [00150] Figure 16 is a diagram showing a format of a user info field, according to some embodiments. The user info field shown in the diagram is an EHT variant user info field.

[00151] As shown in the diagram, the user info field may include an AID12 field 1602 (12 bits), a RU allocation field 1604 (8 bits), a UL FEC coding type field 1606 (1 bit), a UL EHT- MCS field 1608 (4 bits), a reserved field 1610 (1 bit), a SS allocation field 1612 (6 bits), a UL target receive power field 1614 (7 bits), a PS160 field 1616 (1 bit), and a trigger dependent user info field 1618 (variable length). The bit positions of the fields may be as shown in the diagram. [00152] In an embodiment, the reserved field 1610 included in the common info field may be used for carrying dynamic bandwidth signaling information (e.g., a bit indicating whether dynamic bandwidth signaling is being requested). Additionally or alternatively, in an embodiment, if a trigger frame that includes the user info field is being used solely for the purpose of dynamic bandwidth signaling, the UL EHT-MCS field 1608 and/or the SS allocation field 1612 can be used for carrying dynamic bandwidth signaling information. The other fields can be interpreted according to IEEE 802.11 wireless networking standards (e.g., EHT).

[00153] In an embodiment, a reserved field of a MU-RTS TXOP sharing (MU-RTS TXS) frame (which is a type of trigger frame) can be used for carrying an indication of dynamic bandwidth signaling.

[00154] Figure 17 is a diagram showing a format of a user info field of a MU-RTS TXS frame, according to some embodiments. The user info field shown in the diagram is an EHT variant user info field. [00155] As shown in the diagram, the user info field includes an AID12 field 1702 (12 bits), a RU allocation field 1704 (8 bits), an allocation duration field 1706 (9 bits), a reserved field 1708 (10 bits), and a PS160 field 1710 (1 bit). The bit positions of the fields may be as shown in the diagram. In an embodiment, the reserved field 1708 included in the user info field is used for carrying dynamic bandwidth signaling information. The other fields can be interpreted according to IEEE 802.11 wireless networking standards (e.g., EHT).

[00156] Since the STA receiving a MU-RTS frame is likely to be a single receiver, there are no constraints on providing available bandwidth information in the CTS frame’s SERVICE field. As defined in existing IEEE 802.11 wireless networking standards, the indication of "Dynamic" through DYN BANDWIDTH IN NON HT should be discernible to the receiving device. This can be perceived through the reception of the MU-RTS frame, allowing the CTS frame’s scrambling sequence to carry information about the available bandwidth in response. The scrambling sequence may be generated based on the TXVECTOR in cases where dynamic bandwidth signaling is supported during CTS frame transmission. Figure 18 is a diagram showing a scrambling sequence encoding, according to some embodiments. The scrambling sequence encoding shown in the diagram is an example encoding used in EHT. If the initial control frame is a BSRP frame and the initial control response frame is a multi-STA BA frame, it may be possible to transmit information for multiple users/STAs in the multi-STA BA frame (e.g., to convey bandwidth information). This is because, in the case of a multi-STA BA frame, even if bandwidth information is included per user/STA, each user/STA’s MPDU is included in the uplink trigger-based PPDU so there is no risk of collision. Also, when a BSRP frame is transmitted to a single user/STA, it may be transmitted using a non-HT PPDU format, which should allow sufficient capacity to provide the necessary information.

[00157] As mentioned above, an AP may transmit an initial control frame to a STA to cause the STA to use a wider bandwidth (e.g., to switch operation modes from a low power listen mode to a wider bandwidth mode). The AP may add padding to the initial control frame to prevent collisions from occurring at other STAs that are within the transmission range of the STA receiving the initial control frame.

[00158] The padding that is added to the initial control frame can be simple padding that does not encode any meaningful information. However, in an embodiment, the padding added to the initial control frame can include/encode meaningful/useful information.

[00159] For example, the padding may include one or more of the following information: [00160] 1) An intermediate FCS that certain STAs (e.g., UHR STAs and STAs that implement subsequent wireless networking standards) can understand. A STA that receives a frame that includes the intermediate FCS and understand the intermediate FCS may use the intermediate FCS to verify the integrity of the frame before fully receiving the entire frame.

[00161] 2) Padding to account for a mode switching delay.

[00162] 3) A bit for indicating dynamic bandwidth signaling.

[00163] 4) Information regarding power-off links and which link to activate if multiple links are established between STAs.

[00164] 5) A permission indication regarding sending control frames containing denial-to-send information if NAV values are set due to virtual CCA at the receiver of the initial control frame. [00165] It is recognized by the present disclosure that the length of padding that needs to be added to the initial control frame in order to prevent collisions depends on: 1) the transmission rate at which the initial control frame is to be transmitted; and 2) what type of ACK frame is to be transmitted by STAs that are hidden to the initial control frame transmitter and the transmission rate at which the ACK frame is to be transmitted.

[00166] Figure 19 is a diagram showing the length of padding that needs to be added to an initial control frame to prevent collisions from occurring in the worst case scenario, according to some embodiments.

[00167] As shown in the diagram, it is important that the CTS frames transmitted by STA1 and the ACK frames transmitted by STA2 (which is hidden to API) do not collide at AP2. Also, there should be a time gap of aRxPHYDelay (“@”) between t4 and t5. Having this time gap allows AP2 to properly overhear/receive the CTS frames from STA1.

[00168] The minimum padding duration that is needed to prevent the CTS frames and the ACK frames from colliding with each other while ensuring the aRxPHYDelay may be calculated using Equations (1) to (4) shown in Figure 20.

[00169] Figure 20 is a diagram showing equations for determining the minimum padding duration, according to some embodiments. In the equations, t2 is the time at which the initial control frame (e.g., the (MU-)RTS frames) is transmitted, tl is the time at which transmission of the OBSS frame (e.g., the 40 MHz PPDU) ends, ACKtimeout is the ACK timeout duration, aSIFStime is a SIFS interval duration, aSlotTime is a slot duration, P is aRxPHYStartDelay, ICFtxtime is the transmission duration of the initial control frame, Min Pad duration is the minimum padding duration, AckTxTime is the transmission duration of an ACK frame, @ is aRxPHYDelay, and t5 is the time at which the initial control response frame (e.g., the CTS frames) is transmitted.

[00170] As can be derived from the four equations shown in the diagram, the minimum padding duration may be determined according to the following equation: [00171] min_pad_duration = AckTxTime + aSlotTime + aRxPHYStartDelay - ICFTxtime, where min_pad_duration is the minimum padding duration, AckTxTime is the transmission duration of an ACK frame, aSlotTime is a slot duration, aRxPHYStartDelay is the duration for a physical layer to notify a MAC layer of a received signal, and ICFTxtime is the transmission duration of the initial control frame.

Equation I

[00172] It is noted that the variables AckTxtime and ICFTxtime may vary depending on the size and transmission rate of the ACK frame and the initial control frame.

[00173] Figure 21 is a diagram showing the durations of different types of ACK frames for different transmission rates, according to some embodiments.

[00174] An ACK frame may be a normal ACK frame, a compressed block ACK frame, a multi-STA ACK frame, or a Multi-TID block ACK frame. Different types of ACK frames may have different sizes. It is assumed that ACK frames can be transmitted at the basic transmission rates of 6, 12, or 24 Megabits per second (Mbps). As shown in the diagram, a normal ACK frame may have a size of 14 bytes. The transmission duration of the normal ACK frame may be 44 ps, 32 ps, or 28 ps depending on the transmission rate. A compressed BA frame may have a size of 32 bytes (bitmap size is 8 bytes) or 56 bytes (bitmap size is 32 bytes). If the size of the compressed BA frame is 32 bytes, the transmission duration of the compressed BA frame may be 68 ps, 44 ps, or 32 ps depending on the transmission rate. If the size of the compressed BA frame is 56 bytes, the transmission duration of the compressed BA frame may be 100 ps, 60 ps, or 40 ps depending on the transmission rate. A multi-STA frame or multi-TID frame may have a size of 34 bytes, 46 bytes, or 70 bytes depending on the number of users. If the size of the multi-STA frame or multi-TID frame is 34 bytes, the transmission duration of the frame may be 68 ps, 44 ps, or 32 ps depending on the transmission rate. If the size of the multi-STA frame or multi-TID frame is 46 bytes, the transmission duration of the frame may be 84 ps, 52 ps, or 36 ps depending on the transmission rate. If the size of the multi-STA frame or multi-TID frame is 70 bytes, the transmission duration of the frame may be 116 ps, 68 ps, or 52 ps depending on the transmission rate. While certain types of ACK frames and ACK frame sizes are shown in the diagram, it should be appreciated that there can be other types of ACK frames and that ACK frames can have different sizes than shown in the diagram. For example, for multi-STA or multi-TID frames, the bitmap size can be up to 128 bytes and the number of users can be larger than four.

[00175] Figure 22 is a diagram showing the durations of different types of initial control frames for different transmission rates, according to some embodiments. [00176] The transmission duration of the initial control frame may depend on the size of the initial control frame. The size of an initial control frame may depend on the information it contains. In an embodiment, the initial control frame is a type of a trigger frame. Thus, the initial control frame may include basic trigger frame fields having a size of 24 bytes, a user info field (e.g., for specifying the recipient) having a size of 5 bytes, two additional user info fields (e.g., for intermediate FCS or padding purposes) each having a size of 5 bytes, one byte padding (for byte alignment purposes), and a frame check sequence field having a size of 4 bytes. Thus, the total size of the initial control frame may be 44 bytes. The transmission duration of the initial control frame may thus be 64 ps, 32 ps, or 16 ps depending on the transmission rate, assuming that that the initial control frame can be transmitted at the basic transmission rates of 6, 12, or 24 Mbps. While the diagram assumes that certain information/fields are included in the initial control frame and that the initial control frame has a size of 44 bytes, it should be appreciated that the initial control frame can include additional information/fields and/or omit certain information/fields, and that the initial control frame can have a size other than 44 bytes. [00177] In general, the minimum duration of the padding added to an initial control frame to prevent collisions from occurring may depend on the initial control frame transmission duration and the ACK frame transmission duration mentioned above. The minimum padding duration may be converted to a minimum padding length using the transmission rate at which the initial control frame is to be transmitted. The minimum padding lengths for different ACK frame transmission rates, ACK frame types, and initial control frame transmission rates are shown in Figures 23, 24, and 25 to illustrate some examples.

[00178] Figure 23 is a diagram showing the minimum padding lengths to add to an initial control frame depending on the transmission rate of the initial control frame and the ACK frame type when the transmission rate of the ACK frame is 6 Mbps, according to some embodiments. [00179] As shown in the diagram, when the transmission rate of the ACK frame is 6 Mbps, the minimum padding lengths to add to the initial control frame may range from 0 bytes to 327 bytes depending on the transmission rate of the initial control frame (e.g., which can be 6 Mbps, 12 Mbps, or 24 Mbps) and the ACK frame type (e.g., which can be a normal ACK frame, a compressed BA frame, a compressed BA frame (32 byte bitmap), a multi-STA BA frame for 2 users, or a multi-STA BA frame for 4 users).

[00180] Figure 24 is a diagram showing the minimum padding lengths to add to an initial control frame depending on the transmission rate of the initial control frame and the ACK frame type when the transmission rate of the ACK frame is 12 Mbps, according to some embodiments. [00181] As shown in the diagram, when the transmission rate of the ACK frame is 12 Mbps, the minimum padding lengths to add to the initial control frame may range from 0 bytes to 183 bytes depending on the transmission rate of the initial control frame (e.g., which can be 6 Mbps, 12 Mbps, or 24 Mbps) and the ACK frame type (which can be a normal ACK frame, a compressed BA frame, a compressed BA frame (32 byte bitmap), a multi-STA BA frame for 2 users, or a multi-STA BA frame for 4 users).

[00182] Figure 25 is a diagram showing the minimum padding lengths to add to an initial control frame depending on the transmission rate of the initial control frame and the ACK frame type when the transmission rate of the ACK frame is 24 Mbps, according to some embodiments. [00183] As shown in the diagram, when the transmission rate of the ACK frame is 24 Mbps, the minimum padding lengths to add to the initial control frame may range from 0 bytes to 135 bytes depending on the transmission rate of the initial control frame (e.g., which can be 6 Mbps, 12 Mbps, or 24 Mbps) and the ACK frame type (e.g., which can be a normal ACK frame, a compressed BA frame, a compressed BA frame (32 byte bitmap), a multi-STA BA frame for 2 users, or a multi-STA BA frame for 4 users).

[00184] In the case of hidden node operation, the AP that transmits the initial control frame may not know the type and transmission rate of the ACK frame that is to be transmitted in an OBSS (e.g., it may not be able to collect such information from the OBSS). When there is a lack of information regarding the type and/or transmission rate of the ACK frame, the AP may choose to use the most conservative strategy, which is to assume that the ACK frame is transmitted at the lowest transmission rate possible. In such case, the AP may determine the length of the padding to add to the initial control frame based on the transmission rate and size of the initial control frame. The AP may refer to Equation I set forth above (or similar equation) and/or refer to one of the tables shown in Figures 23-25 (or similar tables) to determine the minimum padding length to add to the initial control frame. In an embodiment, the AP may extend the padding to align the padding to a byte unit for word alignment in the initial control frame.

[00185] If the AP is able to obtain BA session information from neighboring OBSS STAs or STAs associated with the AP are able to collect the information and report it to the AP, the AP may be able to predict which type of ACK frame hidden nodes will transmit and/or predict the transmission rate at which hidden nodes will transmit the ACK frame. The AP may use the predicted ACK frame type and/or the predicted ACK frame transmission rate when determining the length of padding to add to the initial control frame. The AP may use the most conservative strategy, which is to predict the largest possible ACK frame size and/or the lowest possible transmission rate that can be used.

[00186] When examining the minimum padding length trends (e.g., trends of the padding lengths shown in Figures 23-25), it can be observed that the minimum padding length increases as the transmission rate of the initial control frame increases and the size of the hidden STA's ACK frame increases. Thus, when determining the length of the padding to add to the initial control frame, the transmitter of the initial control frame should protect against the lowest ACK frame transmission rate and the largest ACK frame size. Also, rather than simply adding simple padding, including/encoding useful information in the padding, as mentioned above, can help the receiver (e.g., STA) perform more refined operations.

[00187] The padding technique disclosed herein may allow a STA operating in a low power listen mode (listening to the minimum receiving bandwidth) to switch operation modes to a wider bandwidth operation mode and transmit frames using the wider bandwidth without causing collisions. A STA inevitably incurs a mode switching delay after receiving the initial control frame to switch operation modes (e.g., to activate the necessary hardware to operate in the wider bandwidth operation mode). Also, to achieve wide channel bandwidth access, it is important to ensure that the PIFS idleness requirement is observed before receiving the initial control frame. However, this is not feasible for the STA due to hardware limitations. To address this problem, padding may be added to the initial control frame to protect hidden STAs during dynamic bandwidth signaling. This helps ensure that the frame exchange sequences involving neighboring STAs of the STA receiving the initial control frame are protected. The length of padding added to the initial control frame may affect the efficiency of the wireless network. The present disclosure provides a way to determine the minimum padding length needed to be added to an initial control frame during dynamic bandwidth signaling to prevent collisions. By not adding more padding than is necessary for preventing collisions, overall network efficiency can be improved. In general, if the padding/delay needed for preventing collisions is longer than the padding/delay needed to account for the mode switching delay, the longer padding/delay should be used. For the sake of illustration only, the padding technique is primarily described herein in the context of performing dynamic bandwidth signaling.

However, it should be appreciated that the padding technique described herein can be adapted and applied to other contexts where a STA might switch from operating in a narrower bandwidth mode to a wider bandwidth mode. That is, the padding technique may help prevent collisions in other situations where a STA attempts to perform wider bandwidth access. [00188] Turning now to Figure 26, a method 2600 will be described for preventing collisions during dynamic bandwidth signaling, in accordance with an example embodiment. The method 2600 may be performed by an AP. The AP may be implemented by a wireless device (e.g., wireless device 104).

[00189] Additionally, although shown in a particular order, in some embodiments the operations of the method 2600 (and the other methods shown in the other figures) may be performed in a different order. For example, although the operations of the method 2600 are shown in a sequential order, some of the operations may be performed in partially or entirely overlapping time periods.

[00190] At operation 2605, the AP generates an initial control frame. In an embodiment, the initial control frame is a RTS frame. In an embodiment, the initial control frame is a trigger frame. For example, the initial control frame may be a MU-RTS frame for a single user or a BSRP frame. In an embodiment where the initial control frame is a MU-RTS frame for a single user, the MU-RTS frame for the single user may include dynamic bandwidth signaling information. In an embodiment, the dynamic bandwidth signaling information is included in a common information field of the MU-RTS frame or a user information field of the MU-RTS frame. In an embodiment, the initial control frame is a MU-RTS TXS frame, wherein the MU- RTS TXS frame includes a user information field that carries dynamic bandwidth signaling information. Dynamic bandwidth signaling may be used in the process of determining available channel bandwidth during TXOP sharing in coordinated-TDMA schemes. While the MU-RTS TXS frame is used in a coordinated-TDMA scheme to share a TXOP, it may also serve the purpose of determining available channel bandwidth.

[00191] At operation 2610, the AP determines a minimum padding length to add to an end of the initial control frame based on a transmission duration of the initial control frame. In an embodiment, the AP determines (or predicts) which type of ACK frame is to be transmitted in an OBSS of the AP and determines (or predicts) a transmission rate to be used in the OBSS to transmit the ACK frame. In such an embodiment, as shown in block 2615, the minimum padding length may be further determined based on a type of ACK frame to be transmitted in an OBSS of the AP and a transmission rate to be used in the OBSS to transmit the ACK frame. In an embodiment, the AP determines the lowest transmission rate that can be used in an OBSS of the AP to transmit an ACK frame. In such an embodiment, as shown in block 2620, the minimum padding length may be further determined based on a lowest transmission rate that can be used in an OBSS of the AP to transmit an ACK frame. [00192] In an embodiment, the minimum padding length corresponds to a minimum padding duration, wherein the minimum padding duration is determined based on the following equation: min_pad_duration = AckTxTime + aSlotTime + aRxPHYStartDelay - ICFTxtime, wherein min_pad_duration is the minimum padding duration, AckTxTime is a transmission duration of an acknowledgement (ACK) frame, aSlotTime is a slot duration, aRxPHYStartDelay is a duration for a physical layer to notify a MAC layer of a received signal, and ICFTxtime is the transmission duration of the initial control frame.

[00193] At operation 2625, the AP transmits the initial control frame with padding having at least the minimum padding length to STA to cause the STA to switch from operating in a first mode to operating in a second mode, wherein the STA uses a wider bandwidth when the STA operates in the second mode compared to when the STA operates in the first mode. In an embodiment, the STA uses a 20 MHz bandwidth when operating in the first mode (e.g., the first mode may be a low power listen mode). In an embodiment, the padding includes one or more of the following: padding to prevent collisions from occurring at STAs that are in communication range of the STA when the STA uses the wider bandwidth, an intermediate FCS, padding to account for a mode switching delay, a bit for indicating dynamic bandwidth signaling, information regarding power-off links and which link to activate if multiple links are established between the AP and the STA, and a permission indication regarding sending control frames containing denial-to-send information.

[00194] In an embodiment, the AP receives an initial control response frame from the STA in the wider bandwidth as a response to the initial control frame. In an embodiment, the initial control frame is a CTS frame. In an embodiment, the initial control response frame is a multi- STA BA frame.

[00195] An embodiment is a method performed by a first wireless device to perform dynamic bandwidth signaling. The method may include generating a channel reservation control frame that includes dynamic bandwidth signaling information, wherein the dynamic bandwidth signaling information includes information regarding a requested bandwidth, transmitting the channel reservation control frame to a second wireless device, and receiving a channel reservation response control frame from the second wireless device that includes an indication of an available bandwidth within the requested bandwidth. In an embodiment, the channel reservation control frame is a MU-RTS frame for a single user or MU-RTS TXS frame for a single user and the channel reservation response control frame is a CTS frame. In an embodiment, the channel reservation control frame is a BSRP trigger frame and the channel reservation response control frame is a multi-STA BA frame. In an embodiment, the dynamic bandwidth signaling information further includes a dynamic bandwidth signaling indication (indicating that dynamic bandwidth signaling is being performed). In an embodiment, the dynamic bandwidth signaling information further includes a punctured channel bitmap. In an embodiment, the transmitting the channel reservation control frame to the second wireless device causes the second wireless device to switch from operating in a first mode to operating in a second mode, wherein the second wireless device uses a wider bandwidth when the second wireless device operates in the second mode compared to when the second wireless device operates in the first mode. The first wireless device (that performs the method described above) may be an AP or a non-AP STA (e.g., the first wireless device may implement a non-AP STA in cases where non-AP STAs are allowed to transmit trigger frames).

[00196] 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.

[00197] 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.

[00198] 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.

[00199] It should be borne in mind, however, that all of these and similar terms are to be associated with the appropriate physical quantities and are merely convenient labels applied to these quantities. The present disclosure can refer to the action and processes of a computer system, or similar electronic computing device, that manipulates and transforms data represented as physical (electronic) quantities within the computer system's registers and memories into other data similarly represented as physical quantities within the computer system memories or registers or other such information storage systems.

[00200] 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.

[00201] 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.

[00202] 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. [00203] 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

CLAIMS What is claimed is:

1. A method performed by an access point (AP) to prevent collisions during dynamic bandwidth signaling, the method comprising: generating an initial control frame; determining a minimum padding length to add to an end of the initial control frame based on a transmission duration of the initial control frame; and transmitting the initial control frame with padding having at least the minimum padding length to a STA to cause the STA to switch from operating in a first mode to operating in a second mode, wherein the STA uses a wider bandwidth when the STA operates in the second mode compared to when the STA operates in the first mode.

2. The method of claim 1, further comprising: determining what type of acknowledgement (ACK) frame is to be transmitted in an overlapping basic service set (OBSS) of the AP; and determining a transmission rate to be used in the OBSS to transmit the ACK frame, wherein the minimum padding length is further determined based on the type of ACK frame to be transmitted in the OBSS and the transmission rate to be used in the OBSS to transmit the ACK frame.

3. The method of claim 1, wherein the minimum padding length is further determined based on a lowest transmission rate that can be used in an overlapping basic service set (OBSS) of the AP to transmit an acknowledgement (ACK) frame.

4. The method of claim 1, wherein the minimum padding length corresponds to a minimum padding duration, wherein the minimum padding duration is determined based on the following equation: min_pad_duration = AckTxTime + aSlotTime + aRxPHYStartDelay - ICFTxtime, wherein min_pad_duration is the minimum padding duration, AckTxTime is a transmission duration of an acknowledgement (ACK) frame, aSlotTime is a slot duration, aRxPHYStartDelay is a duration for a physical layer to notify a media access control (MAC) layer of a received signal, and ICFTxtime is the transmission duration of the initial control frame.

5. The method of claim 1, wherein the initial control frame is a request-to-send (RTS) frame.

6. The method of claim 1, wherein the initial control frame is a trigger frame.

7. The method of claim 6, wherein the initial control frame is a multi-user request-to-send (MU-RTS) frame for a single user.

8. The method of claim 7, wherein the MU-RTS frame includes dynamic bandwidth signaling information.

9. The method of claim 8, wherein the dynamic bandwidth signaling information is included in a common information field of the MU-RTS frame or a user information field of the MU-RTS frame.

10. The method of claim 6, wherein the initial control frame is a multi-user request-to-send transmission opportunity sharing (MU-RTS TXS) frame, wherein the MU-RTS TXS frame includes a user information field that carries dynamic bandwidth signaling information.

11. The method of claim 6, wherein the initial control frame is a buffer status report poll (BSRP) frame.

12. The method of claim 1, further comprising: receiving an initial control response frame from the STA in the wider bandwidth as a response to the initial control frame.

13. The method of claim 12, wherein the initial control response frame is a clear-to-send (CTS) frame.

14. The method of claim 12, wherein the initial control response frame is a multi-station block acknowledgement (BA) frame.

15. The method of claim 1, wherein the padding includes one or more of the following: padding to prevent collisions from occurring at STAs that are in communication range of the STA when the STA uses the wider bandwidth; an intermediate frame check sequence (FCS); padding to account for a mode switching delay; a bit for indicating dynamic bandwidth signaling; information regarding power-off links and which link to activate if multiple links are established between the AP and the STA; and a permission indication regarding sending control frames containing deni al -to- send information.

16. The method of claim 1, wherein the STA uses a 20 Megahertz (MHz) bandwidth when operating in the first mode.

17. A method performed by a first wireless device to perform dynamic bandwidth signaling, the method comprising: generating a channel reservation control frame that includes dynamic bandwidth signaling information, wherein the dynamic bandwidth signaling information includes information regarding a requested bandwidth; transmitting the channel reservation control frame to a second wireless device; and receiving a channel reservation response control frame from the second wireless device that includes an indication of an available bandwidth within the requested bandwidth.

18. The method of claim 17, wherein the channel reservation control frame is a multi-user request-to-send (MU-RTS) frame for a single user or a MU-RTS transmission opportunity sharing (MU-RTS TXS) frame for a single user and the channel reservation response control frame is a clear-to-send (CTS) frame.

19. The method of claim 17, wherein the channel reservation control frame is a buffer status report poll (BSRP) trigger frame and the channel reservation response control frame is a multi - STA block acknowledgement (BA) frame.

20. The method of claim 17, wherein the dynamic bandwidth signaling information further includes a dynamic bandwidth signaling indication.

21. The method of claim 20, wherein the dynamic bandwidth signaling information further includes a punctured channel bitmap.

22. The method of claim 17, wherein the transmitting the channel reservation control frame to the second wireless device causes the second wireless device to switch from operating in a first mode to operating in a second mode, wherein the second wireless device uses a wider bandwidth when the STA operates in the second mode compared to when the second wireless device operates in the first mode.

23. The method of claim 17, wherein the first wireless device implements an access point (AP) or a non-AP STA.

24. A wireless device to implement an access point (AP), the wireless device comprising: a radio frequency transceiver; a memory device storing a set of instructions; and a processor coupled to the memory device, wherein the set of instructions, when executed by the processor, causes the AP to perform the method of any one of claims 1-16.

25. A wireless device comprising: a radio frequency transceiver; a memory device storing a set of instructions; and a processor coupled to the memory device, wherein the set of instructions, when executed by the processor, causes the wireless device to perform the method of any one of claims 17-22.