Traffic management during the limited target wake time (TWT) service period

Abstract

The present disclosure provides a system, method, and apparatus, including a computer program encoded on a computer storage medium, for managing data traffic in a restricted target wake time (TWT) service period (SP). In some aspects, an access point (AP) may transmit a packet when a restricted TWT SP begins, signaling all non-member wireless stations (STAs) to postpone access to the wireless medium for at least a threshold duration. Upon receiving the packet, any non-member STAs associated with the AP may set their network allocation vector (NAV) according to the duration indicated by the duration field of the received packet. In some implementations, low-latency STAs that are members of the TWT SP may not set their NAV according to the duration field of the received packet. Instead, the low-latency STAs may access the wireless medium before the NAV associated with the non-member STAs expires.

Description

[Technical Field]

[0001] Cross-reference of related applications

[0001] This patent application claims priority to U.S. Patent Application No. 17 / 402,391, filed on 13 August 2021, entitled "TRAFFIC MANAGEMENT IN RESTRICTED TARGET WAKE TIME (TWT) SERVICE PERIODS," which has been assigned to the assignee of this application. All prior application disclosures are deemed to be part of this patent application and are incorporated into this patent application by reference.

[0002]

[0002] This disclosure relates in general to wireless communications, and more specifically to managing data traffic during a limited target wake time (TWT) service period. [Background technology]

[0003]

[0003] A wireless local area network (WLAN) can be formed by one or more access points (APs) that provide a shared wireless medium for use by several client devices or stations (STAs). Each AP, which may support a Basic Service Set (BSS), may periodically broadcast beacon frames to enable any STA within the AP's wireless range to establish and maintain a communication link with the WLAN. A WLAN operating according to the IEEE 802.11 standard family is commonly referred to as a Wi-Fi network.

[0004]

[0004] Some wireless communication devices may be associated with low-latency applications that have strict end-to-end latency, throughput, and timing requirements for data traffic. Exemplary low-latency applications include, but are not limited to, real-time gaming applications, video communications, and augmented reality (AR) and virtual reality (VR) applications (collectively referred to as extended reality (XR) applications). Such low-latency applications may specify a variety of latency, throughput, and timing requirements for the wireless communication system providing connectivity to these applications. Therefore, it is desirable to ensure that the WLAN can meet the various latency, throughput, and timing requirements of such low-latency applications. [Overview of the Initiative]

[0005]

[0005] The systems, methods, and devices of this disclosure each have several innovative aspects, and none of any single aspect thereof alone possesses the desirable characteristics disclosed herein.

[0006]

[0006] One innovative aspect of the subject matter described herein may be implemented as a method of wireless communication. The method may be performed by a wireless communication device to manage data traffic during a limited target wake time (TWT) service period (SP). In some implementations, the method may include: performing a channel sensing operation to indicate whether a wireless channel is busy or idle; and transmitting a first packet over the wireless channel in response that the channel sensing operation indicated that the wireless channel associated with the limited TWT SP was idle for a threshold duration for the start of the limited TWT SP at a first time, the first packet including a duration field indicating the duration for which the wireless channel is reserved, and the channel sensing operation further indicating that the wireless channel was busy at a second time after the first time, less than the duration indicated by the duration field of the first packet.

[0007]

[0007] Another innovative aspect of the subject matter described herein may be implemented in a wireless communication device. The wireless communication device may include a processing system configured to perform channel sensing operations that indicate whether a wireless channel is busy or idle, and at least one interface, the at least one interface configured to transmit a first packet over the wireless channel in response that the channel sensing operation indicates that at a first time, the wireless channel associated with a limited TWT SP is idle for a threshold duration for the initiation of the limited TWT SP, the first packet including a duration field indicating the duration for which the wireless channel is reserved, and the channel sensing operation further indicates that the wireless channel is busy at a second time after the first time, less than the duration indicated by the duration field of the first packet.

[0008]

[0008] Another innovative aspect of the subject matter described herein may be implemented as a method of wireless communication. The method may be performed by a wireless communication device to manage data traffic in a restricted TWT SP. In some implementations, the method may include, in a first time, receiving a first packet via a wireless channel associated with a restricted TWT SP, which includes a duration field indicating the duration for which the wireless channel is reserved; and in a second time, in response to the first packet, transmitting a second packet via the wireless channel, which is less than the duration indicated by the duration field of the first packet after the first time.

[0009]

[0009] Another innovative aspect of the subject matter described herein may be implemented in a wireless communication device. The wireless communication device may include a processing system and an interface, the interface configured to receive, in a first time, a first packet via a wireless channel associated with a limited TWT SP, which includes a duration field indicating the duration for which the wireless channel is reserved, and in a second time, in response to the first packet, a second packet via the wireless channel which is less than the duration indicated by the duration field of the first packet after the first time.

[0010]

[0010] Details of one or more implementations of the subject matter described herein are described in the accompanying drawings and the following description. Other features, embodiments, and advantages will become apparent from the description, drawings, and claims. Note that the relative dimensions in the following figures may not be drawn to scale. [Brief explanation of the drawing]

[0011] [Figure 1]

[0011] An exemplary block diagram of a wireless system is shown. [Figure 2]

[0012] A block diagram of an exemplary wireless station (STA) is shown. [Figure 3]

[0013] An example block diagram of an access point (AP) is shown. [Figure 4A]

[0014] The timing diagram shows an example of wireless communication between devices belonging to the Basic Service Set (BSS). [Figure 4B]

[0015] The timing diagram shows an example of wireless communication between devices belonging to the BSS. [Figure 4C]

[0016] The timing diagram shows an example of wireless communication between devices belonging to the BSS. [Figure 5]

[0017] A timing diagram showing an example of wireless communication between devices belonging to a BSS is shown. [Figure 6]

[0018] A timing diagram showing an example of wireless communication between devices belonging to a BSS is shown. [Figure 7]

[0019] A timing diagram showing an example of wireless communication between devices belonging to a BSS is shown. [Figure 8A]

[0020] A timing diagram showing an example of wireless communication between devices belonging to a BSS is shown. [Figure 8B]

[0021] A timing diagram showing an example of wireless communication between devices belonging to a BSS is shown. [Figure 9A]

[0022] A timing diagram showing an example of wireless communication between devices belonging to a BSS is shown. [Figure 9B]

[0023] A timing diagram showing an example of wireless communication between devices belonging to a BSS is shown. [Figure 10A]

[0024] A timing diagram showing an example of wireless communication between devices belonging to a BSS is shown. [Figure 10B]

[0025] A timing diagram showing an example of wireless communication between devices belonging to a BSS is shown. [Figure 11A]

[0026] A timing diagram showing an example of wireless communication between devices belonging to a BSS is shown. [Figure 11B]

[0027] A timing diagram showing an example of wireless communication between devices belonging to a BSS is shown. [Figure 12]

[0028] An illustrative flowchart showing an exemplary wireless communication operation is shown. [Figure 13]

[0029] An illustrative flowchart showing an exemplary wireless communication operation is shown. [Figure 14]

[0030] A block diagram of an exemplary wireless communication device is shown. [Figure 15]

[0031] A block diagram of an exemplary wireless communication device is shown.

[0012]

[0032] Similar reference numbers and names in various drawings refer to the same elements. [Modes for carrying out the invention]

[0013]

[0033] The following description focuses on several specific implementations for the purpose of illustrating innovative aspects of the present disclosure. However, those skilled in the art will readily recognize that the teachings herein can be applied in numerous different ways. The implementations described may be implemented in any device, system, or network capable of transmitting and receiving radio frequency (RF) signals in accordance with one or more of the following: Long Term Evolution (LTE®), 3G, 4G, or 5G (New Radio, NR) standards published by the 3rd Generation Partnership Project (3GPP®), the Institute of Electrical and Electronics Engineers (IEEE) 802.11 standard, the IEEE 802.15 standard, or the Bluetooth® standard defined by the Bluetooth® Special Interest Group (SIG). The implementations described may be implemented in any device, system, or network capable of transmitting and receiving RF signals according to one or more of the following technologies or techniques: code division multiple access (CDMA), time division multiple access (TDMA), frequency division multiple access (FDMA), orthogonal FDMA (OFDMA), single-carrier FDMA (SC-FDMA), single-user (SU) multiple-input multiple-output (MIMO), and multi-user (MU) MIMO.The described implementations may also be implemented using other wireless communication protocols or RF signals suitable for use in one or more of the following: wireless wide area networks (WWAN), wireless personal area networks (WPAN), wireless local area networks (WLAN), or Internet of Things (IoT) networks.

[0014]

[0034] Many wireless networks use random channel access mechanisms to control access to a shared wireless medium. In these wireless networks, wireless communication devices (including access points (APs) and wireless stations (STAs)) compete with each other using carrier-sense multiple access / collision avoidance (CA) techniques to gain access to the wireless medium. Generally, a wireless communication device that randomly selects the lowest back-off number (RBO) wins the medium access competition and may be granted access to the wireless medium for a period of time generally called a transmit opportunity (TXOP). Other wireless communication devices are generally not allowed to transmit during another wireless communication device's TXOP to avoid collisions on the shared wireless medium.

[0015]

[0035] Some random channel access mechanisms, such as enhanced distributed channel access (EDCA), give high-priority traffic a greater chance of gaining media access than low-priority traffic. EDCA categorizes data into different access categories (ACs), such as voice (AC_VO), video (AC_VI), best-effort (AC_BE), and background (AC_BK). Each AC is associated with a different priority level and can be assigned different ranges of RBOs (Routing Booleans) so that higher-priority data is more likely to win TXOPs than lower-priority data (e.g., by assigning lower RBOs to higher-priority data and higher RBOs to lower-priority data). While EDCA increases the likelihood that low-latency data traffic will gain access to a shared wireless medium during a given competition period, the unpredictable consequences of media access competition behavior can prevent low-latency applications from achieving a certain level of throughput or meeting certain latency requirements.

[0016]

[0036] The IEEE 802.11be revision of the IEEE 802.11 standard describes a restricted target wake time (TWT) service period (SP) that can be used to provide more predictable latency, reduced worst-case latency, or reduced jitter, along with greater reliability for latency-sensitive traffic. Where used herein, the term “non-legacy STA” may refer to any STA that supports restricted TWT operation, and the term “low-latency STA” may refer to any non-legacy STA that has latency-sensitive traffic to transmit or receive. In contrast, the term “legacy STA” may refer to any STA that does not support restricted TWT operation. The IEEE 802.11be revision requires all non-legacy STAs that are TXOP holders outside of a restricted TWT SP to terminate their respective TXOPs before the commencement of any restricted TWT SP to which they are not members. While membership in a restricted TWT SP is reserved for low-latency STAs, current rules regarding restricted TWT SPs do not prevent non-member STAs from obtaining TXOPs during a restricted TWT SP. As a result, some non-member STAs may gain access to the shared wireless medium during a restricted TWT SP, even in the presence of SP members. Therefore, a new communication protocol or mechanism is needed to further protect latency-sensitive traffic in restricted TWT SPs.

[0017]

[0037] Implementations of the subject matter described herein may be used to manage data traffic in a restricted TWT SP. In some embodiments, an AP may send a packet at the start of a restricted TWT SP that explicitly signals all non-member STAs to postpone access to the wireless medium for at least a threshold duration. For example, the threshold duration may be indicated by the duration field in the medium access control (MAC) header of the packet. Upon receiving the packet, any non-member STA associated with the AP may set their network allocation vector (NAV) according to the duration indicated by the duration field. In some implementations, the packet may be a trigger frame requesting a trigger-based (TB) physical layer convergence protocol (PLCP) protocol data unit (PDU) (PPDU) from one or more low-latency STAs. In some other implementations, the header packet may be a clear-to-send (CTS) frame. In such implementations, any low-latency STA that is a member of a TWT SP may ignore CTS frames directed to it. In other words, low-latency STAs may not set their NAV according to the duration indicated by the duration field of the CTS frame directed to them. Furthermore, in some implementations, a packet may be a multi-user (MU) request-to-send (RTS) frame that identifies one or more low-latency STAs. In such implementations, each low-latency STA identified by the MU-RTS may send a CTS frame in response to the MU-RTS frame without setting its NAV according to the duration field of the MU-RTS frame.

[0018]

[0038] In some other embodiments, non-legacy STAs that are not members of the restricted TWT SP may be required (e.g., through implicit signaling) to postpone access to the wireless medium for at least a threshold duration at the start of the restricted TWT SP. In some implementations, non-legacy STAs may be required to reset their RBOs at the start of the restricted TWT SP. Thus, each non-legacy STA (including low-latency STAs that are members of the SP and non-member STAs) that has data to transmit or receive at the start of the restricted TWT SP must compete for medium access from the start of the restricted TWT SP. In some other implementations, non-legacy STAs may be required to postpone access to the shared wireless medium for the duration of the restricted TWT SP. Thus, any non-member STA that has data to transmit or receive during the restricted TWT SP must refrain from accessing the shared wireless medium until after the restricted TWT SP has ended. Furthermore, in some embodiments, the AP may suppress traffic from all non-legacy STAs that are not members of the restricted TWT SP for at least a threshold duration at the start of the restricted TWT SP. For example, an AP may broadcast a beacon frame containing a quiet element indicating the quiet duration associated with a limited TWT SP. Upon receiving such a beacon frame, any non-member STA with data to transmit or receive during the limited TWT SP must postpone access to the shared wireless medium for at least the quiet duration indicated in the beacon frame.

[0019]

[0039] Certain implementations of the subject matter described herein may be implemented to achieve one or more of the following potential benefits: By requiring non-member STAs to postpone media access for a threshold duration at the start of a restricted TWT through explicit or implicit signaling, aspects of the disclosure can significantly improve the latency gain achievable by latency-sensitive traffic through the application of a restricted TWT SP. For example, under current rules regarding restricted TWT SPs, a non-member STA already in the process of counting down its RBO at the start of a restricted TWT SP may gain access to the shared wireless medium before any low-latency STA that is a member of the SP. However, additional requirements imposed on non-member STAs (via the signaling techniques of the disclosure) may protect low-latency STAs from losing media access at the start of a restricted TWT SP. Thus, aspects of the disclosure can ensure that latency-sensitive traffic takes precedence over all other traffic during a restricted TWT SP. As a result, limited TWT SPs can provide more predictable latency, reduced worst-case latency, or reduced jitter, along with greater reliability for latency-sensitive traffic.

[0020]

[0040] Figure 1 shows a block diagram of an exemplary wireless system 100. The wireless system 100 is illustrated to include a wireless access point (AP) 110 and several wireless stations (STAs) 120a-120i. For simplicity, only one AP 110 is illustrated in Figure 1. The AP 110 may form a wireless local area network (WLAN) that enables the AP 110, STAs 120a-120i, and other wireless devices (not shown for simplicity) to communicate with each other over a wireless medium. The wireless medium, which may be divided into several channels or several resource units (RUs), can facilitate wireless communication between the AP 110, STAs 120a-120i, and other wireless devices connected to the WLAN. In some implementations, STAs 120a-120i can communicate with each other using peer-to-peer communication (e.g., without the presence or involvement of the AP 110). The AP 110 may be assigned a unique MAC address, which is programmed therein, for example, by the access point manufacturer. Similarly, each of the STA120a to STA120i can also be assigned a unique MAC address.

[0021]

[0041] In some implementations, the wireless system 100 may support a multi-input multiple-output (MIMO) wireless network and may support single-user MIMO (SU-MIMO) and multi-user (MU-MIMO) communication. In some implementations, the wireless system 100 may support orthogonal frequency division multiple access (OFDMA) communication. While the WLAN is shown in Figure 1 as an infrastructure basic service set (BSS), in other implementations, the WLAN may be an independent basic service set (IBSS), an extended service set (ESS), an ad-hoc network, or a peer-to-peer (P2P) network (such as one operating according to one or more Wi-Fi Direct protocols).

[0022]

[0042] STA120a~120i may be any suitable Wi-Fi-enabled wireless device, including, for example, a mobile phone, personal digital assistant (PDA), tablet device, laptop computer, or similar. STA120a~120i may also be referred to as user equipment (UE), subscriber station, mobile unit, subscriber unit, wireless unit, remote unit, mobile device, wireless device, wireless communication device, remote device, mobile subscriber station, access terminal, mobile terminal, wireless terminal, remote terminal, handset, user agent, mobile client, client, or by any other appropriate terminology.

[0023]

[0043] AP110 may be any suitable device that enables one or more wireless devices (such as STA120a to STA120i) to connect to a network (such as a local area network (LAN), wide area network (WAN), metropolitan area network (MAN), or the Internet). In some implementations, the system controller 130 may facilitate communication between AP110 and other networks or systems. In some implementations, the system controller 130 may facilitate communication between AP110 and one or more other APs (not shown for brevity) that may be associated with other wireless networks. Additionally or alternatively, AP110 may exchange signals and information with one or more other APs using wireless communication.

[0024]

[0044] AP110 may periodically broadcast beacon frames to enable STA120a-120i and other wireless devices within AP110's wireless range to establish and maintain a communication link with AP110. Beacon frames indicating downlink (DL) data transmission to STA120a-120i and requesting or scheduling uplink (UL) data transmission from STA120a-120i are typically broadcast according to a target beacon transmission time (TBTT) schedule. Broadcast beacon frames may include AP110's timing synchronization function (TSF) values. STA120a-120i may synchronize their own local TSF values ​​with the broadcasted TSF values, for example, so that all STA120a-120i are synchronized with each other and with AP110.

[0025]

[0045] In some implementations, each of the stations STA120a to STA120i and AP110 may include one or more transceivers, one or more processing resources (processors or application-specific integrated circuits (ASICs)), one or more memory resources, and a power supply (such as a battery). The one or more transceivers may include Wi-Fi transceivers, Bluetooth transceivers, cellular transceivers, or other suitable radio frequency (RF) transceivers (not shown for brevity) for transmitting and receiving wireless communication signals. In some implementations, each transceiver may communicate with other wireless devices in a distinguishable frequency band and / or using a distinguishable communication protocol. The memory resources may include non-temporary computer-readable media (such as one or more non-volatile memory elements, such as EPROM, EEPROM®, flash memory, or hard drives) for storing instructions to perform one or more operations as described with respect to Figures 5 to 11.

[0026]

[0046] Figure 2 shows a block diagram of an exemplary wireless station (STA) 200. STA 200 may be at least one implementation of STA 120a to 120i from Figure 1. STA 200 may include one or more transceivers 210, a processor 220, a user interface 230, memory 240, and several antennas ANT1 to ANTn. Transceiver 210 may be coupled to antennas ANT1 to ANTn either directly or through an antenna selection circuit (not shown for brevity). Transceiver 210 may be used to transmit signals to and receive signals from other wireless devices, for example, several APs and several other STAs. Although not shown in Figure 2 for brevity, transceiver 210 may include any number of transmit chains to process signals and transmit them to other wireless devices via antennas ANT1 to ANTn, and any number of receive chains to process signals received from antennas ANT1 to ANTn. Thus, STA 200 may be configured for MIMO and OFDMA communication. MIMO communication may include SU-MIMO and MU-MIMO communication. In some implementations, the STA200 may use multiple antennas ANT1 to ANTn to provide antenna diversity. Antenna diversity may include polarization diversity, pattern diversity, and spatial diversity.

[0027]

[0047] The processor 220 may be any suitable one or more processors capable of executing scripts or instructions of one or more software programs stored in the STA200 (for example, in memory 240). In some implementations, the processor 220 may be one or more microprocessors providing processor functions and external memory providing at least a portion of machine-readable media, or may include them. In other implementations, the processor 220 may be an application-specific integrated circuit (ASIC) with a processor, bus interface, user interface, and at least a portion of machine-readable media integrated on a single chip, or may include them. In some other implementations, the processor 220 may be one or more field-programmable gate arrays (FPGAs) or programmable logic devices (PLDs), or may include them.

[0028]

[0048] In some implementations, the processor 220 can be a component of a processing system. A processing system generally refers to a system or set of machines or components that receive inputs, process those inputs, and produce a set of outputs (which may be passed to other systems or components of STA200, for example). For example, the processing system of STA200 may refer to a system that includes various other components or sub-components of STA200.

[0029]

[0049] The STA200 processing system may interface with other components of the STA200, and may process information (such as inputs or signals) received from other components, and output information to other components. For example, the STA200 chip or modem may be coupled to or include a processing system, a first interface for outputting information, and a second interface for acquiring information. In some cases, the first interface may refer to an interface between the chip or modem's processing system and a transmitter, such that the STA200 can transmit information output from the chip or modem. In some cases, the second interface may refer to an interface between the chip or modem's processing system and a receiver, such that the STA200 can acquire information or signal inputs and information can be passed to the processing system. A person skilled in the art will readily recognize that the first interface can also acquire information or signal inputs, and the second interface can also output information or signal outputs.

[0030]

[0050] The user interface 230 coupled to the processor 220 may be, or represent, several suitable user input devices, such as a speaker, microphone, display device, keyboard, or touchscreen. In some implementations, the user interface 230 may allow the user to control several operations of the STA200 for interacting with one or more applications that can be executed by the STA200, as well as other suitable functions.

[0031]

[0051] In some implementations, the STA200 may include a satellite positioning system (SPS) receiver 250. The SPS receiver 250, coupled to the processor 220, may be used to acquire and receive signals transmitted from one or more satellites or satellite systems via an antenna (not shown for brevity). The signals received by the SPS receiver 250 may be used to determine (or at least assist in determining) the location of the STA200.

[0032]

[0052] Memory 240 may include a device database 241 that can store location data, configuration information, data rate, media access control (MAC) address, timing information, modulation and coding scheme (MCS), traffic indication (TID) queue size, ranging capability, and other appropriate information about (or related to) the STA200. The device database 241 may also store profile information about several other wireless devices. Profile information about a given wireless device may include, for example, service set identification (SSID), basic service set identifier (BSSID), operating channel, TSF value, beacon interval, ranging schedule, channel state information (CSI), received signal strength indicator (RSSI) value, goodput value, and connection history with the STA200. In some implementations, profile information about a given wireless device may also include clock offset value, carrier frequency offset value, and ranging capability.

[0033]

[0053] The memory 240 is also a non-temporary computer-readable storage medium (such as one or more non-volatile memory elements, such as an EPROM, EEPROM, flash memory, or hard drive) capable of storing computer-executable instructions 242 for performing all or part of one or more operations described in this disclosure.

[0034]

[0054] Figure 3 shows a block diagram of an exemplary access point (AP) 300. AP300 may be one implementation of AP110 in Figure 1. AP300 may include one or more transceivers 310, a processor 320, memory 330, a network interface 340, and several antennas ANT1 to ANTn. Transceiver 310 may be coupled to antennas ANT1 to ANTn either directly or through an antenna selection circuit (not shown for brevity). Transceiver 310 may be used to transmit signals to and receive signals from other wireless devices, including, for example, one or more of the STA120a to 120i and other APs in Figure 1. Although not shown in Figure 3 for brevity, transceiver 310 may include any number of transmit chains to process signals and transmit signals to other wireless devices via antennas ANT1 to ANTn, and may include any number of receive chains to process signals received from antennas ANT1 to ANTn. Thus, AP300 may be configured for MIMO and OFDMA communication. MIMO communication may include SU-MIMO and MU-MIMO communication. In some implementations, the AP300 may use multiple antennas ANT1 to ANTn to provide antenna diversity. Antenna diversity may include polarization diversity, pattern diversity, and spatial diversity.

[0035]

[0055] In high-frequency (60 GHz or millimeter wave (mmWave), etc.) wireless communication systems (such as those conforming to the IEEE 802.11 standard, specifically the IEEE 802.11ad or 802.11ay revisions), communication may be beamformed using phased array antennas at the transmitter and receiver. Beamforming generally refers to a wireless communication technique in which transmitting and receiving devices adjust their transmit or receive antenna configurations to achieve a desired link budget for subsequent communication. A procedure for adapting the transmitting and receiving antennas, called beamforming training, may be performed initially to establish a link between the transmitting and receiving devices and may be performed periodically to maintain a quality link using optimized transmit and receive beams.

[0036]

[0056] The processor 320 may be any suitable one or more processors capable of executing scripts or instructions of one or more software programs stored in the AP300 (for example, in memory 330). In some implementations, the processor 320 may be one or more microprocessors providing processor functions and external memory providing at least a portion of machine-readable media, or may include them. In other implementations, the processor 320 may be an ASIC with a processor, bus interface, user interface, and at least a portion of machine-readable media integrated on a single chip, or may include them. In some other implementations, the processor 320 may be one or more FPGAs or PLDs, or may include them. In some implementations, the processor 320 may be a component of a processing system. For example, the processing system of the AP300 may refer to a system that includes various other components or sub-components of the AP300.

[0037]

[0057] The AP300's processing system may interface with other components of the AP300, and may process information (such as inputs or signals) received from other components, and output information to other components. For example, the AP300's chip or modem may include a processing system, a first interface for outputting information, and a second interface for acquiring information. In some cases, the first interface may refer to an interface between the chip or modem's processing system and a transmitter, which may transmit information output from the chip or modem to the AP300. In some cases, the second interface may refer to an interface between the chip or modem's processing system and a receiver, which may allow the AP300 to acquire information or signal inputs and pass information to the processing system. A person skilled in the art will readily recognize that the first interface may also acquire information or signal inputs, and the second interface may also output information or signal outputs.

[0038]

[0058] The network interface 340 coupled to the processor 320 may be used to communicate with the system controller 130 in Figure 1. The network interface 340 may also enable the AP 300 to communicate directly or through one or more intervening networks with other wireless systems, other APs, one or more backhaul networks, or any combination thereof.

[0039]

[0059] Memory 330 may include a device database 331 that can store location data, configuration information, data rate, MAC address, timing information, MCS, ranging capability, and other appropriate information about (or relating to) AP300. The device database 331 may also store profile information about several other wireless devices (such as one or more of stations 120a to 120i in Figure 1). Profile information about a given wireless device may include, for example, the SSID, BSSID, operating channel, CSI, received signal strength indicator (RSSI) value, goodput value, and connection history with AP300 for the wireless device. In some implementations, profile information about a given wireless device may also include the TID queue size, preferred packet duration for trigger-based UL transmission, and the maximum amount of queued UL data that the wireless device can insert into the TB PPBU.

[0040]

[0060] The memory 330 is also a non-temporary computer-readable storage medium (such as one or more non-volatile memory elements, such as an EPROM, EEPROM, flash memory, or hard drive) capable of storing computer-executable instructions 332 for performing all or part of one or more operations described in this disclosure.

[0041]

[0061] Figure 4A shows a timing diagram 400 illustrating an example of wireless communication between devices belonging to a BSS. In the example in Figure 4A, the BSS is shown to include a low-latency STA402 and a non-legacy STA404. The low-latency STA402 is a member of a limited TWT SP (r-TWT SP) over a duration from time t3 to t8, while the non-legacy STA404 is not a member of a limited TWT SP (and is therefore sometimes referred to as a "non-member STA"). In some implementations, each of STA402 and 404 could be an example of either STA120a-120i in Figure 1 or STA200 in Figure 2. Although only one low-latency STA and one non-legacy STA are shown in the example in Figure 4A, in actual implementations, the BSS may include any number of low-latency STAs and any number of non-legacy STAs.

[0042]

[0062] The non-legacy STA404 attempts to access the shared wireless medium before initiating a limited TWT SP. More specifically, the non-legacy STA404 senses that the medium is idle for a threshold duration from time t0 to t1, based on channel sensing behavior (such as clear channel assessment, CCA), and further counts down a random backoff (RBO) duration from time t1 to t2 before attempting to acquire a TXOP. For example, the threshold duration (from time t0 to t1) could be the arbitration interframe spacing (AIFS) duration associated with a particular access category (AC) of data traffic. Thus, the RBO duration (from time t1 to t2) could be randomly selected from a range of RBOs across the competition window associated with the AC. At time t2, the non-legacy STA404 senses that the wireless medium is still idle and proceeds to acquire a TXOP, for example, by initiating a transmission over the shared medium. However, existing rules regarding restricted TWT operation require non-member STAs to terminate their TXOPs upon the start of a restricted TWT SP. Since the restricted TWT SP in Figure 4A starts at time t3, the non-legacy STA 404 must shorten its TXOP between times t2 and t3.

[0043]

[0063] The low-latency STA402 attempts to access the shared wireless medium at the start of the limited TWT SP. More specifically, the low-latency STA402 senses that the medium is idle during the AIFS duration from time t3 to t4, and further counts down the RBO duration from time t4 to t6 before attempting to acquire the TXOP. In the example in Figure 4A, the non-legacy STA404 also attempts to access the shared wireless medium at the start of the limited TWT SP. For example, the non-legacy STA404 senses that the medium is idle during the AIFS duration from time t3 to t5, and further counts down the RBO duration starting at time t5. In some implementations, data traffic associated with the low-latency STA402 may be assigned to ACs with higher priority than data traffic associated with the non-legacy STA404. Therefore, the AIFS or RBO duration associated with the low-latency STA402 may be shorter than the AIFS or RBO duration associated with the non-legacy STA404, respectively. As a result, the low-latency STA402 gains access to the wireless medium at time t6 and obtains TXOP, for example, by initiating transmission over the shared medium.

[0044]

[0064] At time t6, the non-legacy STA404 senses that the wireless medium is busy and refrains from accessing the shared medium for the duration of the TXOP. After the TXOP has ended, at time t7, the non-legacy STA404 may attempt to access the wireless medium again. In this way, the limited TWT operation can prioritize latency-sensitive traffic within the BSS, for example, by requiring other non-legacy STAs to terminate their TXOPs upon the initiation of the limited TWT SP. Furthermore, an AP (not shown for brevity) can suppress traffic from all legacy STAs associated with the BSS by scheduling a quiet interval to overlap with the limited TWT SP. For example, the duration of the quiet interval may be indicated by one or more quiet elements contained within management frames (such as beacon frames and probe response frames) sent by the AP before the initiation of the limited TWT SP.

[0045]

[0065] Figure 4B shows a timing diagram 410 illustrating an example of wireless communication between devices belonging to a BSS. In the example in Figure 4B, the BSS is shown to include a low-latency STA412 and a non-legacy STA414. The low-latency STA412 is a member of a limited TWT SP (r-TWT SP) over a duration from time t2 to t6, while the non-legacy STA414 is not a member of the limited TWT SP (and is therefore sometimes referred to as a "non-member STA"). In some implementations, each of STA412 and 414 could be an example of either STA120a-120i in Figure 1 or STA200 in Figure 2. Although only one low-latency STA and one non-legacy STA are shown in the example in Figure 4B, in actual implementations, the BSS may include any number of low-latency STAs and any number of non-legacy STAs.

[0046]

[0066] The non-legacy STA414 attempts to access the shared wireless medium before the start of the limited TWT SP. More specifically, the non-legacy STA414 senses that the medium is idle during the AIFS duration from time t0 to t1, and further counts down the RBO duration from time t1 to t4 before attempting to acquire a TXOP. In the example in Figure 4B, the RBO duration randomly selected by the non-legacy STA414 is greater than the amount of time remaining before the start of the limited TWT SP (from time t1 to t2). However, existing rules regarding limited TWT operation do not prevent the RBO countdown from extending beyond the start of the limited TWT SP. At time t4, the non-legacy STA414 senses that the wireless medium is still idle and proceeds to acquire a TXOP, for example, by initiating a transmission over the shared wireless medium. As a result, the non-legacy STA414 acquires access to the shared wireless medium during the limited TWT SP, from time t4 to t5. Since the non-legacy STA414 does not acquire its TXOP before the start of the restricted TWT SP, the TXOP (from time t4 to t5) does not violate any existing rules regarding restricted TWT operation.

[0047]

[0067] The low-latency STA412 attempts to access the shared wireless medium at the start of the limited TWT SP. More specifically, the low-latency STA412 senses that the medium is idle during the AIFS duration from time t2 to t3, and further counts down the RBO duration which begins at time t3. In some implementations, data traffic associated with the low-latency STA412 may be assigned to ACs with higher priority than data traffic associated with the non-legacy STA414. Therefore, the AIFS or RBO duration associated with the low-latency STA412 may be shorter than the AIFS or RBO duration associated with the non-legacy STA414, respectively. However, since the non-legacy STA414 started its RBO countdown before the start of the limited TWT SP, the non-legacy STA414 can obtain TXOP before the low-latency STA412 completes its RBO countdown. As a result, the low-latency STA412 senses that the wireless medium is busy at time t4 and refrains from accessing the shared wireless medium for the duration of the non-legacy STA414's TXOP. After the TXOP ends, at time t5, the low-latency STA412 can attempt to access the wireless medium again.

[0048]

[0068] Figure 4C shows a timing diagram 420 illustrating an example of wireless communication between devices belonging to a BSS. In the example in Figure 4C, the BSS is shown to include a low-latency STA422 and a non-legacy STA424. The low-latency STA422 is a member of a limited TWT SP (r-TWT SP) over a duration from time t3 to t7, while the non-legacy STA424 is not a member of a limited TWT SP (and is therefore sometimes referred to as a "non-member STA"). In some implementations, each of STA422 and 424 could be an example of either STA120a-120i in Figure 1 or STA200 in Figure 2. Although only one low-latency STA and one non-legacy STA are shown in the example in Figure 4C, in actual implementations, the BSS may include any number of low-latency STAs and any number of non-legacy STAs.

[0049]

[0069] A non-legacy STA424 attempts to access the shared wireless medium before the limited TWT SP begins. More specifically, the non-legacy STA424 senses that the medium is idle during the AIFS duration from time t0 to t1, and further counts down the RBO duration from time t1 to t2 before attempting to acquire a TXOP. In the example in Figure 4C, the RBO countdown ends (at time t2) before the limited TWT SP begins. However, the non-legacy STA424 may determine that the duration between the end of the RBO countdown and the start of the limited TWT SP (from time t2 to t3) is not suitable for a (shortened) TXOP. Therefore, in some implementations, the non-legacy STA424 may perform a new RBO countdown from time t2 to t5. At time t5, the non-legacy STA424 senses that the wireless medium is still idle and proceeds to acquire a TXOP, for example, by initiating a transmission over the shared wireless medium. As a result, the non-legacy STA424 gains access to the shared wireless medium during the limited TWT SP from time t5 to t6. Since the non-legacy STA424 does not acquire its TXOP before the start of the limited TWT SP, the TXOP (from time t5 to t6) does not violate any existing rules regarding limited TWT operation.

[0050]

[0070] The low-latency STA422 attempts to access the shared wireless medium at the start of the limited TWT SP. More specifically, the low-latency STA422 senses that the medium is idle during the AIFS duration from time t3 to t4, and further counts down the RBO duration starting at time t4. In some implementations, data traffic associated with the low-latency STA422 may be assigned to ACs with higher priority than data traffic associated with the non-legacy STA424. Therefore, the AIFS or RBO duration associated with the low-latency STA422 may be shorter than the AIFS or RBO duration associated with the non-legacy STA424, respectively. However, since the non-legacy STA424 started its RBO countdown before the start of the limited TWT SP, the non-legacy STA424 can obtain TXOP before the low-latency STA422 completes its second RBO countdown. As a result, the low-latency STA422 senses that the wireless medium is busy at time t5 and refrains from accessing the shared wireless medium for the duration of the non-legacy STA424's TXOP. After the TXOP ends, at time t6, the low-latency STA422 may attempt to access the wireless medium again.

[0051]

[0071] Figures 4B and 4C illustrate that, under various conditions, a non-member STA may acquire a TXOP during a restricted TWT SP before a low-latency STA that is a member of the restricted TWT SP. While the low-latency STA may access the wireless medium upon completion of the non-member STA's TXOP, such delays in medium access can significantly increase the latency of data traffic associated with the low-latency STA 412. Thus, existing rules regarding restricted TWT operation may not provide adequate protection for latency-sensitive traffic. Aspects of this disclosure may provide greater protection for latency-sensitive traffic by preventing non-member STAs from accessing the shared wireless medium for at least a threshold duration following the initiation of a restricted TWT SP. In some aspects, all non-member STAs may be subject to one or more rules requiring such STAs to postpone access to the shared wireless medium for at least a threshold duration at the initiation of each restricted TWT SP. In some other embodiments, the AP may send one or more frames to all non-member STAs that delay access to the shared wireless medium for at least a threshold duration at the start of the restricted TWT SP.

[0052]

[0072] Figure 5 shows a timing diagram 500 illustrating an example of wireless communication between devices belonging to a BSS. In the example in Figure 5, the BSS is shown to include low-latency STA502 and 504 and non-legacy STA506. Low-latency STA502 and 504 are connected from time t0 to t 10STA506 is a member of the limited TWT SP (r-TWT SP) for a duration up to a certain point, while the non-legacy STA506 is not a member of the limited TWT SP. In some implementations, each of STA502-506 could be an example of either STA120a-120i in Figure 1 or STA200 in Figure 2. Although only two low-latency STAs and one non-legacy STA are shown in the example in Figure 5, in actual implementations, the BSS may include any number of low-latency STAs and any number of non-legacy STAs.

[0053]

[0073] The first low-latency STA502 attempts to access the shared wireless medium at the start of the limited TWT SP. More specifically, the first low-latency STA502 senses that the medium is idle during the AIFS duration from time t0 to t2, and further counts down the RBO duration from time t2 to t4 before attempting to acquire TXOP. In the example in Figure 5, the second low-latency STA504 also attempts to access the shared wireless medium at the start of the limited TWT SP.

[0054]

[0074] In some implementations, to reduce the possibility of collisions between low-latency STA 502 and 504, the second low-latency STA 504 may wait for a conflict offset duration from time t0 to t1 before competing for media access. As a result, the first low-latency STA 502 wins access to the wireless media and obtains a TXOP from time t4 to t5. During the TXOP, the first low-latency STA 502 may send latency-sensitive traffic to or receive latency-sensitive traffic from an AP or another STA (e.g., in peer-to-peer communication). The second low-latency STA 504 senses that the media is idle for the AIFS duration from time t1 to t3 and further counts down the RBO duration starting at time t3. However, at time t4, the second low-latency STA 504 senses that the wireless media is busy and refrains from accessing the shared media for the duration of the TXOP.

[0055]

[0075] In some implementations, all non-legacy STAs may be required to reset their RBO at the start of each restricted TWT SP. In other words, any non-member STA with data to transmit or receive during a restricted TWT SP must compete for media access from the beginning of the restricted TWT SP. A non-legacy STA 506 may attempt to access the shared wireless medium before the start of a restricted TWT SP (as described with reference to Figures 4A-4C). However, regardless of whether the non-legacy STA 506 obtains a shortened TXOP or continues to count down its RBO, the non-legacy STA 506 must again compete for media access at the start of a restricted TWT SP.

[0056]

[0076] The non-legacy STA506 senses that the medium is idle during the AIFS duration from time t0 to t3, and further counts down the RBO duration which begins at time t3. In some implementations, data traffic associated with the non-legacy STA506 may be assigned to ACs with lower priority than data traffic associated with the low-latency STA502 and 504. As a result, the non-legacy STA506 loses access to the medium to the first low-latency STA502. At time t4, the non-legacy STA506 senses that the wireless medium is busy and refrains from accessing the shared medium for the duration of the TXOP.

[0057]

[0077] After the TXOP of the first low-latency STA502 has finished, at time t5, the second low-latency STA504 and the non-legacy STA506 may compete again for access to the wireless medium. As shown in Figure 5, the second low-latency STA504 senses that the medium is idle during the AIFS duration from time t5 to t6, and further counts down the RBO duration from time t6 to t8 before attempting to acquire the TXOP. The non-legacy STA506 senses that the medium is idle during the AIFS duration from time t5 to t7, and further counts down the RBO duration starting at time t7.

[0058]

[0078] In some implementations, data traffic associated with the second low-latency STA504 may be assigned to a higher priority AC than data traffic associated with the non-legacy STA506. As a result, the second low-latency STA504 wins access to the wireless medium and obtains a TXOP from time t8 to t9. At time t8, the non-legacy STA506 senses that the wireless medium is busy and refrains from accessing the shared medium for the duration of its TXOP. After the second low-latency STA504's TXOP ends, at time t9, the non-legacy STA506 may compete again for access to the wireless medium.

[0059]

[0079] In some implementations, membership in a restricted TWT SP may be limited so that each low-latency STA associated with the SP has a greater chance of acquiring a TXOP in a relatively short timeframe. For example, referring to Figure 5, if membership in a restricted TWT SP is limited to 2, any additional low-latency STAs in the BSS may be assigned to different restricted TWT SPs.

[0060]

[0080] In the example in Figure 5, it is assumed that data traffic associated with the non-legacy STA506 is assigned to an AC with a lower priority than data traffic associated with the low-latency STA502 and 504. However, in some cases, data traffic associated with each of the STA502-506 may be assigned to the same AC. In such cases, the likelihood of either the low-latency STA502 or 504 winning access to the wireless medium over the non-legacy STA506 is significantly reduced. In some implementations, non-member STAs may be prohibited from accessing the wireless medium during a restricted TWT SP in order to further protect latency-sensitive traffic in the restricted TWT SP.

[0061]

[0081] Figure 6 shows a timing diagram 600 illustrating an example of wireless communication between devices belonging to a BSS. In the example in Figure 6, the BSS is shown to include low-latency STAs 602 and 604 and a non-legacy STA 606. The low-latency STAs 602 and 604 are members of a limited TWT SP (r-TWT SP) over a duration from time t0 to t8, while the non-legacy STA 606 is not a member of a limited TWT SP. In some implementations, each of STAs 602-606 could be an example of either STAs 120a-120i in Figure 1 or STA 200 in Figure 2. Although only two low-latency STAs and one non-legacy STA are shown in the example in Figure 6, in actual implementations, the BSS may include any number of low-latency STAs and any number of non-legacy STAs.

[0062]

[0082] The first low-latency STA602 attempts to access the shared wireless medium at the start of the limited TWT SP. More specifically, the first low-latency STA602 senses that the medium is idle during the AIFS duration from time t0 to t2, and further counts down the RBO duration from time t2 to t4 before attempting to acquire TXOP. In the example in Figure 6, the second low-latency STA604 also attempts to access the shared wireless medium at the start of the limited TWT SP.

[0063]

[0083] In some implementations, to reduce the possibility of conflict between low-latency STA602 and STA604, the second low-latency STA604 may wait for a conflict offset duration from time t0 to t1 before competing for media access. As a result, the first low-latency STA602 wins access to the wireless media and obtains a TXOP from time t4 to t5. During the TXOP, the first low-latency STA602 may send latency-sensitive traffic to or receive latency-sensitive traffic from an AP or another STA (e.g., in peer-to-peer communication). The second low-latency STA604 senses that the media is idle for the AIFS duration from time t1 to t3 and further counts down the RBO duration starting at time t3. However, at time t4, the second low-latency STA604 senses that the wireless media is busy and refrains from accessing the shared media for the duration of the TXOP.

[0064]

[0084] In some implementations, all non-legacy STAs may be required to postpone access to the shared wireless medium for the duration of each restricted TWT SP. In other words, any non-member STA with data to transmit or receive during a restricted TWT SP must wait until the restricted TWT SP has ended before competing for medium access. Non-legacy STA 606 may attempt to access the wireless medium before the start of a restricted TWT SP (as described with reference to Figures 4A-4C). However, regardless of whether non-legacy STA 606 obtains a shortened TXOP or continues counting down the RBO, non-legacy STA 606 must postpone medium access for the duration of the restricted TWT SP, from time t0 to t8.

[0065]

[0085] After the TXOP of the first low-latency STA602 has finished, at time t5, the second low-latency STA604 may again compete for access to the wireless medium. As shown in Figure 6, the second low-latency STA604 senses that the medium is idle during the AIFS duration from time t5 to t6, counts down the RBO duration from time t6 to t7, and takes TXOP from time t7 to t8. After the limited TWT SP has finished, at time t8, the non-legacy STA606 may again compete for access to the wireless medium. As shown in Figure 6, the non-legacy STA606 senses that the medium is idle during the AIFS duration from time t8 to t9, and further counts down the RBO duration starting at time t9.

[0066]

[0086] In some implementations, membership in a restricted TWT SP may be limited so that each low-latency STA associated with the SP has a greater chance of acquiring a TXOP in a relatively short timeframe. For example, referring to Figure 6, if membership in a restricted TWT SP is limited to 2, any additional low-latency STA in the BSS may be assigned to a different restricted TWT SP.

[0067]

[0087] Aspects of this disclosure recognize that, in some cases, a low-latency STA assigned to a restricted TWT SP may not utilize all (or any) of the SP to transmit or receive latency-sensitive traffic. In such cases, requiring a non-member STA to postpone media access for the duration of the restricted TWT SP may result in insufficient utilization of the shared wireless medium. In some implementations, to improve media utilization during a restricted TWT SP, a non-member STA may be required to postpone media access for only a portion of the restricted TWT SP.

[0068]

[0088] Figure 7 shows a timing diagram 700 illustrating an example of wireless communication between devices belonging to a BSS. In the example in Figure 7, the BSS is shown to include low-latency STA702 and 704 and non-legacy STA706. Low-latency STA702 and 704 are shown from time t0 to t 11 STA706 is a member of the limited TWT SP (r-TWT SP) for a duration up to a certain point, while the non-legacy STA706 is not a member of the limited TWT SP. In some implementations, each of STA702-706 could be an example of either STA120a-120i in Figure 1 or STA200 in Figure 2. Although only two low-latency STAs and one non-legacy STA are shown in the example in Figure 7, in actual implementations, the BSS may include any number of low-latency STAs and any number of non-legacy STAs.

[0069]

[0089] The first low-latency STA702 attempts to access the shared wireless medium at the start of the limited TWT SP. More specifically, the first low-latency STA702 senses that the medium is idle during the AIFS duration from time t0 to t2, and further counts down the RBO duration from time t2 to t4 before attempting to acquire TXOP. In the example in Figure 7, the second low-latency STA704 also attempts to access the shared wireless medium at the start of the limited TWT SP.

[0070]

[0090] In some implementations, to reduce the possibility of conflict between low-latency STA 702 and 704, the second low-latency STA 704 may wait for a conflict offset duration from time t0 to t1 before competing for media access. As a result, the first low-latency STA 702 wins access to the wireless media and obtains a TXOP from time t4 to t6. During the TXOP, the first low-latency STA 702 may send latency-sensitive traffic to or receive latency-sensitive traffic from an AP or another STA (e.g., in peer-to-peer communication). The second low-latency STA 704 senses that the media is idle for the AIFS duration from time t1 to t3 and further counts down the RBO duration starting at time t3. However, at time t4, the second low-latency STA 704 senses that the wireless media is busy and refrains from accessing the shared media for the duration of the TXOP.

[0071]

[0091] In some implementations, all non-legacy STAs may be required to postpone access to the shared wireless medium for a period of quiet duration from the start of each restricted TWT SP. In other words, any non-member STA with data to transmit or receive during a restricted TWT SP must wait until the quiet duration expires before competing for access to the medium. In some implementations, the quiet duration may be signaled by an AP (not shown for brevity). For example, the quiet duration may be indicated by a quiet element carried in a management frame (such as a beacon or probe response) transmitted by the AP. A non-legacy STA 706 may attempt to access the wireless medium before the start of a restricted TWT SP (as described with reference to Figures 4A-4C). However, regardless of whether the non-legacy STA 706 obtains a shortened TXOP or continues counting down the RBO, the non-legacy STA 706 must postpone access to the medium for at least the quiet duration from time t0 to t5.

[0072]

[0092] The non-legacy STA706 senses that the wireless medium is busy for the remainder of the TXOP from time t5 to t6. After the TXOP of the first low-latency STA702 ends, at time t6, the second low-latency STA704 and the non-legacy STA706 may compete again for access to the wireless medium. As shown in Figure 7, the second low-latency STA704 senses that the medium is idle during the AIFS duration from time t6 to t7, and further counts down the RBO duration from time t7 to t9 before attempting to acquire the TXOP. The non-legacy STA706 senses that the medium is idle during the AIFS duration from time t6 to t8, and further counts down the RBO duration starting at time t8.

[0073]

[0093] In some implementations, data traffic associated with the second low-latency STA704 may be assigned to ACs with higher priority than data traffic associated with the non-legacy STA706. As a result, the second low-latency STA704 wins access to the wireless medium, from time t9 to t 10 The TXOP is obtained until time t9. The non-legacy STA706 senses that the wireless medium is busy at time t9 and refrains from accessing the shared medium for the duration of the TXOP. After the TXOP of the second low-latency STA704 ends, time t 10 In this scenario, the non-legacy STA706 may once again compete for access to the wireless medium.

[0074]

[0094] In some implementations, membership in a restricted TWT SP may be limited so that each low-latency STA associated with the SP has a greater chance of acquiring a TXOP in a relatively short timeframe. For example, referring to Figure 7, if membership in a restricted TWT SP is limited to 2, any additional low-latency STAs in the BSS may be assigned to different restricted TWT SPs.

[0075]

[0095] In some implementations, the quiescent duration may be chosen to balance the efficiency of media utilization with the latency gain for latency-sensitive traffic. In the example in Figure 7, the quiescent duration is configured to terminate before the termination of a single TXOP. However, in some other implementations, the quiescent duration may be configured to span one or more TXOPs.

[0076]

[0096] The implementations described with reference to Figures 5-7 rely on non-member STAs that adhere to updated rules regarding restricted TWT operation. For example, such updates to the rules may be implemented through future revisions to the IEEE 802.11 standard. However, aspects of this disclosure recognize that non-legacy STAs conforming to existing versions of the IEEE 802.11 standard may not adhere to the updated rules. Therefore, in some other implementations, non-member STAs may be explicitly signaled to postpone media access using existing wireless communication protocols. In such implementations, the AP may capture the wireless medium when the TWT SP begins and send one or more packets causing the non-member STA to postpone media access for at least a threshold interval, while allowing the low-latency STA to access the wireless medium during such intervals.

[0077]

[0097] Figure 8A shows a timing diagram 800 illustrating an example of wireless communication between devices belonging to a BSS. In the example in Figure 8A, the BSS is shown to include AP802, low-latency STA804, and non-legacy STA806. Low-latency STA804 is a member of a limited TWT SP (r-TWT SP) over a duration from time t1 to t9, while non-legacy STA806 is not a member of a limited TWT SP. In some implementations, AP802 may be an example of AP110 in Figure 1 or AP300 in Figure 3. In some implementations, each of STA804 and 806 may be an example of either STA120a-120i in Figure 1 or STA200 in Figure 2. Although only one low-latency STA and one non-legacy STA are shown in the example in Figure 8A, in actual implementations, the BSS may include any number of low-latency STAs and any number of non-legacy STAs.

[0078]

[0098] In some implementations, the AP802 may transmit a clear-to-send (CTS)-to-self frame over the shared wireless medium when the limited TWT SP begins. More specifically, the AP802 attempts to time the transmission of the CTS frame to itself to coincide with the start of the limited TWT SP. In the example in Figure 8A, the non-legacy STA806 counts down its RBO duration before the start of the limited TWT SP. The AP802 senses that the medium is idle during the point coordination function (PCF) interframe space (PIFS) duration from time t0 to t1 and proceeds to transmit the CTS frame to itself at time t1. The low-latency STA804 also attempts to access the shared wireless medium when the limited TWT SP begins. However, the low-latency STA804 senses that the medium is busy from time t1 to t2 while transmitting the CTS frame to itself.

[0079]

[0099] In some implementations, the duration field (in the MAC header) of a CTS frame directed to itself may be used to protect latency-sensitive traffic in a restricted TWT SP. More specifically, the value of the duration field indicates the duration for which the wireless medium should be reserved. STAs compliant with existing versions of the IEEE 802.11 standard must postpone medium access for at least the duration indicated by the duration field. In some implementations, to protect latency-sensitive traffic in a restricted TWT SP, the duration indicated by the duration field may be greater than the duration required to send a trigger frame. As shown in Figure 8A, a non-legacy STA806 sets its Network Allocation Vector (NAV) to the duration indicated by the duration field of the CTS frame directed to itself, over a duration from time t2 to t5.

[0080]

[0100] In some implementations, a low-latency STA may be configured to ignore any CTS frames sent to it by an AP at the start of a limited TWT SP. Therefore, the low-latency STA 804 does not set its NAV according to the duration field of CTS frames sent to it. Instead, the low-latency STA 804 may begin competing for media access immediately after sending a CTS frame to it. As shown in Figure 8A, the low-latency STA 804 senses that the media is idle for the AIFS duration from time t2 to t3, counts down the RBO duration from time t3 to t4, and obtains a TXOP from time t4 to t6. During the TXOP, the low-latency STA 804 may send latency-sensitive traffic to or from an AP or another STA (e.g., in peer-to-peer communication).

[0081]

[0101] At the end of the NAV duration, at time t5, the non-legacy STA806 may compete for media access. However, the non-legacy STA806 senses that the media is busy at time t5 due to the low-latency STA804's TXOP. Therefore, the non-legacy STA806 refrains from accessing the shared media for the duration of the TXOP. After the low-latency STA804's TXOP ends, at time t6, the non-legacy STA806 may again compete for media access. As shown in Figure 8A, the non-legacy STA806 senses that the media is idle during the AIFS duration from time t6 to t7, counts down the RBO duration from time t7 to t8, and takes TXOP from time t8 to t9.

[0082]

[0102] In some implementations, multiple low-latency STAs can be members of a restricted TWT SP. In such implementations, non-legacy STA806s may postpone their media access for even longer (as explained with reference to Figures 5-7). For example, data traffic associated with low-latency STAs may be assigned to higher priority ACs than data traffic associated with non-member STAs, so low-latency STAs are more likely to win media access over non-member STAs during a given competition period.

[0083]

[0103] In some implementations, membership in a restricted TWT SP may be limited so that each low-latency STA associated with the SP has a greater chance of acquiring a TXOP in a relatively short timeframe. For example, referring to Figure 8A, if membership in a restricted TWT SP is limited to 2, any additional low-latency STA in the BSS may be assigned to a different restricted TWT SP.

[0084]

[0104] In some implementations, the duration indicated by the duration field of the CTS frame to itself (also referred to herein as the “NAV duration”) may be selected to balance media utilization efficiency with latency gain for latency-sensitive traffic. In the example in Figure 8A, the NAV duration is configured to terminate before the termination of a single TXOP. However, in some other implementations, the NAV duration may be configured to span one or more TXOPs.

[0085]

[0105] Figure 8B shows a timing diagram 810 illustrating an example of wireless communication between devices belonging to a BSS. In the example in Figure 8B, the BSS is shown to include AP812, low-latency STA814, and non-legacy STA816. Low-latency STA814 is a member of a limited TWT SP (r-TWT SP) over a duration from time t0 to t9, while non-legacy STA816 is not a member of a limited TWT SP. In some implementations, AP812 may be an example of AP110 in Figure 1 or AP300 in Figure 3. In some implementations, each of STA814 and 816 may be an example of either STA120a-120i in Figure 1 or STA200 in Figure 2. Although only one low-latency STA and one non-legacy STA are shown in the example in Figure 8B, in actual implementations, the BSS may include any number of low-latency STAs and any number of non-legacy STAs.

[0086]

[0106] In some implementations, AP812 may transmit a Transmittable to itself (CTS) frame over the shared wireless medium when the Limited TWT SP begins. More specifically, AP812 attempts to time the transmission of a CTS frame to itself to coincide with the start of the Limited TWT SP. In the example in Figure 8B, the non-legacy STA816 obtains a shortened TXOP before the start of the Limited TWT SP. AP812 senses that the medium is idle during the PIFS duration from time t0 to t1 and proceeds to transmit a CTS frame to itself at time t1. Low-latency STA814 also attempts to access the shared wireless medium at the start of the Limited TWT SP. However, since the PIFS duration is shorter than any AIFS duration, AP812 wins the medium access over low-latency STA814. Therefore, low-latency STA814 senses that the medium is busy from time t1 to t2 while transmitting a CTS frame to itself.

[0087]

[0107] In some implementations, the duration field (in the MAC header) of a CTS frame directed to itself may be used to protect latency-sensitive traffic in a limited TWT SP. As illustrated with reference to Figure 8A, an STA compliant with existing versions of the IEEE 802.11 standard must postpone media access for at least the duration indicated by the duration field. In some implementations, to protect latency-sensitive traffic in a limited TWT SP, the duration indicated by the duration field may be greater than the duration required to send the trigger frame. As shown in Figure 8B, a non-legacy STA816 sets its NAV to the duration indicated by the duration field of the CTS frame directed to itself, over a duration from time t2 to t5.

[0088]

[0108] In some implementations, a low-latency STA may be configured to ignore any CTS frames sent to it by an AP at the start of a limited TWT SP. Therefore, the low-latency STA 814 does not set its NAV according to the duration field of CTS frames sent to it. Instead, the low-latency STA 814 may begin competing for wireless medium immediately after sending a CTS frame to it. As shown in Figure 8B, the low-latency STA 814 senses that the medium is idle for the AIFS duration from time t2 to t3, counts down the RBO duration from time t3 to t4, and obtains a TXOP from time t4 to t6. During the TXOP, the low-latency STA 814 may send latency-sensitive traffic to or from an AP or another STA (e.g., in peer-to-peer communication).

[0089]

[0109] At the end of the NAV duration, at time t5, the non-legacy STA816 may compete for media access. However, the non-legacy STA816 senses that the media is busy at time t5 due to the low-latency STA814's TXOP. Therefore, the non-legacy STA816 refrains from accessing the shared media for the duration of the TXOP. After the low-latency STA814's TXOP ends, at time t6, the non-legacy STA816 may again compete for media access. As shown in Figure 8B, the non-legacy STA816 senses that the media is idle during the AIFS duration from time t6 to t7, counts down the RBO duration from time t7 to t8, and takes TXOP from time t8 to t9.

[0090]

[0110] In some implementations, multiple low-latency STAs (not shown for brevity) can be members of a restricted TWT SP. In such implementations, non-legacy STAs 816 may postpone their media access for even longer (as explained with reference to Figures 5-7). For example, data traffic associated with low-latency STAs may be assigned to higher priority ACs than data traffic associated with non-member STAs, so low-latency STAs are more likely to win media access over non-member STAs during a given competition period.

[0091]

[0111] In some implementations, membership in a restricted TWT SP may be limited so that each low-latency STA associated with the SP has a greater chance of acquiring a TXOP in a relatively short timeframe. For example, referring to Figure 8B, if membership in a restricted TWT SP is limited to 2, any additional low-latency STAs in the BSS may be assigned to different restricted TWT SPs.

[0092]

[0112] In some implementations, the NAV duration, indicated by the duration field of the CTS frame to itself, can be chosen to balance media utilization efficiency with latency gain for latency-sensitive traffic. In the example in Figure 8B, the NAV duration is configured to terminate before the termination of a single TXOP. However, in some other implementations, the NAV duration may be configured to span one or more TXOPs.

[0093]

[0113] Figure 9A shows a timing diagram 900 illustrating an example of wireless communication between devices belonging to a BSS. In the example in Figure 9A, the BSS is shown to include AP902, low-latency STA904, and non-legacy STA906. Low-latency STA904 is a member of a limited TWT SP (r-TWT SP) over a duration from time t1 to t8, while non-legacy STA906 is not a member of a limited TWT SP. In some implementations, AP902 may be an example of AP110 in Figure 1 or AP300 in Figure 3. In some implementations, each of STA904 and 906 may be an example of either STA120a-120i in Figure 1 or STA200 in Figure 2. Although only one low-latency STA and one non-legacy STA are shown in the example in Figure 9A, in actual implementations, the BSS may include any number of low-latency STAs and any number of non-legacy STAs.

[0094]

[0114] In some implementations, the AP902 may transmit a trigger frame over the shared wireless medium when the limited TWT SP begins. More specifically, the AP902 attempts to time the transmission of the trigger frame to coincide with the start of the limited TWT SP. In the example in Figure 9A, the non-legacy STA906 counts down its RBO duration before the start of the limited TWT SP. The AP902 senses that the medium is idle during the PIFS duration from time t0 to t1 and proceeds to transmit a trigger frame at time t1. In some implementations, the trigger frame may request trigger-based (TB) physical layer convergence protocol (PLCP) protocol data units (PPDUs) from one or more low-latency STAs (such as the low-latency STA904). As shown in Figure 9A, the low-latency STA904 responds to the trigger frame at time t3 by sending uplink (UL) data in TB PPDU to AP902.

[0095]

[0115] In some implementations, the duration field (in the MAC header) of the trigger frame may be used to protect latency-sensitive traffic in a limited TWT SP. As illustrated with reference to Figure 8A, an STA compliant with existing versions of the IEEE 802.11 standard must postpone media access for at least the duration indicated by the duration field. In some implementations, the duration indicated by the duration field may be greater than the duration required to send the trigger frame. As shown in Figure 9A, a non-legacy STA906 sets its NAV to the duration indicated by the duration field of the trigger frame, spanning from time t2 to t4.

[0096]

[0116] At the end of the NAV duration, at time t4, the non-legacy STA906 may compete for media access. However, the non-legacy STA906 senses that the media is busy at time t4 due to the transmission of the TB PPDU. Therefore, the non-legacy STA906 refrains from accessing the shared media for the duration of the TB PPDU. After the transmission of the TB PPDU is complete, at time t5, the non-legacy STA906 may again compete for media access. As shown in Figure 9A, the non-legacy STA906 senses that the media is idle during the AIFS duration from time t5 to t6, counts down the RBO duration from time t6 to t7, and obtains a TXOP from time t7 to t8.

[0097]

[0117] In some implementations, a trigger frame may be used to request TB PPDU from multiple low-latency STAs (not shown for brevity). In such implementations, multiple low-latency STAs may simultaneously send their respective UL data to AP902 in TB PPDU (from time t3 to t5). In some implementations, AP902 may poll the low-latency STAs before the start of a limited TWT SP to determine which of the STAs (if any) has UL data to send. For example, AP902 may send a buffer status report poll (BSRP) trigger frame to the low-latency STA associated with the limited TWT SP. Each low-latency STA responds to the BSRP trigger frame by sending back a buffer status report (BSR) to AP902 indicating the amount of UL data buffered by the STA. AP902 may use the information carried in each BSR to determine resource allocation for the TB PPDU.

[0098]

[0118] In some implementations, the NAV duration carried in the trigger frame may be chosen to balance media utilization efficiency with latency gain for latency-sensitive traffic. In the example in Figure 9A, the NAV duration is configured to end before the TB PPDU ends. However, in some other implementations, the NAV duration may be configured to extend beyond the duration of the TB PPDU.

[0099]

[0119] Figure 9B shows a timing diagram 910 illustrating an example of wireless communication between devices belonging to a BSS. In the example in Figure 9B, the BSS is shown to include AP912, low-latency STA914, and non-legacy STA916. Low-latency STA914 is a member of a limited TWT SP (r-TWT SP) over a duration from time t0 to t8, while non-legacy STA916 is not a member of a limited TWT SP. In some implementations, AP912 may be an example of AP110 in Figure 1 or AP300 in Figure 3. In some implementations, each of STA914 and 916 may be an example of either STA120a-120i in Figure 1 or STA200 in Figure 2. Although only one low-latency STA and one non-legacy STA are shown in the example in Figure 9B, in actual implementations, the BSS may include any number of low-latency STAs and any number of non-legacy STAs.

[0100]

[0120] In some implementations, the AP912 may transmit a trigger frame over the shared wireless medium when the limited TWT SP begins. More specifically, the AP912 attempts to time the transmission of the trigger frame to coincide with the start of the limited TWT SP. In the example in Figure 9B, the non-legacy STA916 receives a shortened TXOP before the start of the limited TWT SP. The AP912 senses that the medium is idle during the PIFS duration from time t0 to t1 and proceeds to transmit a trigger frame at time t1. The trigger frame requests a TB PPDU from one or more low-latency STAs (such as the low-latency STA914). As shown in Figure 9B, the low-latency STA914 responds to the trigger frame at time t3 by transmitting UL data with a TB PPDU to the AP912.

[0101]

[0121] In some implementations, the duration field (in the MAC header) of the trigger frame may be used to protect latency-sensitive traffic in a limited TWT SP. As illustrated with reference to Figure 8A, an STA compliant with existing versions of the IEEE 802.11 standard must postpone media access for at least the duration indicated by the duration field. Therefore, to protect latency-sensitive traffic, the duration indicated by the duration field may be greater than the duration required to send the trigger frame. As shown in Figure 9B, a non-legacy STA916 sets its NAV to the duration indicated by the duration field of the trigger frame, over a duration from time t2 to t4.

[0102]

[0122] At the end of the NAV duration, at time t4, the non-legacy STA916 may compete for media access. However, the non-legacy STA916 senses that the media is busy at time t4 due to the transmission of the TB PPDU. Therefore, the non-legacy STA916 refrains from accessing the shared media for the duration of the TB PPDU. After the transmission of the TB PPDU is complete, at time t5, the non-legacy STA916 may again compete for media access. As shown in Figure 9B, the non-legacy STA916 senses that the media is idle during the AIFS duration from time t5 to t6, counts down the RBO duration from time t6 to t7, and obtains a TXOP from time t7 to t8.

[0103]

[0123] In some implementations, a trigger frame may be used to request TB PPDU from multiple low-latency STAs (not shown for brevity). In such implementations, multiple low-latency STAs may simultaneously send their respective UL data to AP912 in TB PPDU (from time t3 to t5). In some implementations, AP912 may poll the low-latency STAs before the start of a limited TWT SP to determine which of the STAs (if any) has UL data to send. For example, AP912 may send a BSRP trigger frame to the low-latency STA associated with the limited TWT SP. Each low-latency STA responds to the BSRP trigger frame by sending back a BSR to AP912 indicating the amount of UL data buffered by the STA. AP912 may use the information carried in each BSR to determine resource allocation for TB PPDU.

[0104]

[0124] In some implementations, the NAV duration carried in the trigger frame may be chosen to balance media utilization efficiency with latency gain for latency-sensitive traffic. In the example in Figure 9B, the NAV duration is configured to end before the TB PPDU ends. However, in some other implementations, the NAV duration may be configured to extend beyond the duration of the TB PPDU.

[0105]

[0125] Figure 10A shows a timing diagram 1000 illustrating an example of wireless communication between devices belonging to a BSS. In the example in Figure 10A, the BSS is shown to include AP1002, low-latency STA1004, and non-legacy STA1006. Low-latency STA1004 operates from time t1 to t 11STA1006 is a member of the limited TWT SP (r-TWT SP) for a duration up to a certain point, while the non-legacy STA1006 is not a member of the limited TWT SP. In some implementations, AP1002 may be an example of AP110 in Figure 1 or AP300 in Figure 3. In some implementations, each of STA1004 and 1006 may be an example of STA120a-120i in Figure 1 or STA200 in Figure 2. Although only one low-latency STA and one non-legacy STA are shown in the example in Figure 10A, in actual implementations, the BSS may include any number of low-latency STAs and any number of non-legacy STAs.

[0106]

[0126] In some implementations, AP1002 may transmit a multi-user (MU) request-to-send (RTS) frame over the shared wireless medium when a limited TWT SP begins. More specifically, AP1002 attempts to time the transmission of the MU-RTS frame to coincide with the start of the limited TWT SP. In the example in Figure 10A, the non-legacy STA1006 counts down its RBO duration before the start of the limited TWT SP. Thus, AP1002 senses that the medium is idle during the PIFS duration from time t0 to t1 and proceeds to transmit the MU-RTS frame at time t1. In some implementations, the MU-RTS frame may identify one or more low-latency STAs (such as low-latency STA1004). As shown in Figure 10A, low-latency STA1004 responds to the MU-RTS at time t3 by sending a CTS back to AP1002.

[0107]

[0127] In some implementations, the duration field (in the MAC header) of the MU-RTS frame may be used to protect latency-sensitive traffic in a limited TWT SP. As illustrated with reference to Figure 8A, an STA compliant with existing versions of the IEEE 802.11 standard must postpone media access for at least the duration indicated by the duration field. In some implementations, the duration indicated by the duration field may be greater than the duration required to transmit the MU-RTS frame. As shown in Figure 10A, a non-legacy STA1006 sets its NAV to the duration indicated by the duration field of the MU-RTS frame, over a duration from time t2 to t7. In some other implementations, a non-legacy STA1006 may set its NAV to the duration indicated by the duration field of the CTS frame.

[0108]

[0128] In some implementations, a low-latency STA may be configured to ignore the duration field of the MU-RTS frame sent by the AP at the start of the limited TWT SP. Therefore, the low-latency STA 1004 does not set its NAV according to the duration field of the MU-RTS frame. Instead, the low-latency STA 1004 may begin competing for media access immediately after the CTS transmission. As shown in Figure 10A, the low-latency STA 1004 senses that the media is idle during the AIFS duration from time t4 to t5, counts down the RBO duration from time t5 to t6, and obtains a TXOP from time t6 to t8. During the TXOP, the low-latency STA 1004 may send latency-sensitive traffic to or from an AP or another STA (e.g., in peer-to-peer communication).

[0109]

[0129] At the end of the NAV duration, at time t7, the non-legacy STA1006 may compete for media access. However, at time t7, the non-legacy STA1006 senses that the media is busy due to the low-latency STA1004's TXOP. Therefore, the non-legacy STA1006 refrains from accessing the shared media for the duration of the TXOP. After the low-latency STA1004's TXOP ends, at time t8, the non-legacy STA1006 may again compete for media access. As shown in Figure 10A, the non-legacy STA1006 senses that the media is idle for the duration of the AIFS from time t8 to t9, and from time t9 to t 10 The RBO duration is counted down until time t 10 from t 11 Get TXOP up to this point.

[0110]

[0130] In some implementations, MU-RTS may identify multiple low-latency STAs (not shown for brevity). In such implementations, each low-latency STA may transmit its respective CTS frame from time t3 to t4, depending on the MU-RTS frame. As a result, non-legacy STAs 1006 may postpone their media access for an even longer period (as explained with reference to Figures 5-7). For example, since data traffic associated with a low-latency STA may be assigned to a higher priority AC than data traffic associated with a non-member STA, the low-latency STA is more likely to win media access over a non-member STA during a given competition period.

[0111]

[0131] In some implementations, membership in a restricted TWT SP may be limited so that each low-latency STA associated with the SP has a greater chance of acquiring a TXOP in a relatively short timeframe. For example, referring to Figure 10A, if membership in a restricted TWT SP is limited to 2, any additional low-latency STA in the BSS may be assigned to a different restricted TWT SP.

[0112]

[0132] In some implementations, the NAV duration indicated by the CTS frame's duration field for itself can be selected to balance media utilization efficiency and latency gain for latency-sensitive traffic. In the example of FIG. 10A, the NAV duration is configured to end before the end of a single TXOP. However, in some other implementations, the NAV duration can be configured to span over one or more TXOPs.

[0113]

[0133] FIG. 10B shows a timing diagram 1010 illustrating an example of wireless communication between devices belonging to a BSS. In the example of FIG. 10B, the BSS is shown to include an AP 1012, a low-latency STA 1014, and a non-legacy STA 1016. The low-latency STA 1014 is a member of a restricted TWT SP (r-TWT SP) over a duration from time t0 to t 11 up to, while the non-legacy STA 1016 is not a member of the restricted TWT SP. In some implementations, the AP 1012 can be an example of the AP 110 in FIG. 1 or the AP 300 in FIG. 3. In some implementations, each of the STAs 1014 and 1016 can be an example of any one of the STAs 120a - 120i in FIG. 1 or the STA 200 in FIG. 2. Only one low-latency STA and one non-legacy STA are shown in the example of FIG. 10B, but in an actual implementation, the BSS can include any number of low-latency STAs and any number of non-legacy STAs.

[0114]

[0134] In some implementations, AP1012 may transmit a MU-RTS frame over the shared wireless medium when the limited TWT SP begins. More specifically, AP1012 attempts to time the transmission of the MU-RTS frame to coincide with the start of the limited TWT SP. In the example in Figure 10B, the non-legacy STA1016 receives a shortened TXOP before the start of the limited TWT SP. AP1012 senses that the medium is idle during the PIFS duration from time t0 to t1 and proceeds to transmit a MU-RTS frame at time t1. In some implementations, the MU-RTS frame may identify one or more low-latency STAs (such as low-latency STA1014). As shown in Figure 10B, low-latency STA1014 responds to the MU-RTS at time t3 by sending a CTS back to AP1012.

[0115]

[0135] In some implementations, the duration field (in the MAC header) of the MU-RTS frame may be used to protect latency-sensitive traffic in a limited TWT SP. As illustrated with reference to Figure 8A, an STA compliant with existing versions of the IEEE 802.11 standard must postpone media access for at least the duration indicated by the duration field. In some implementations, the duration indicated by the duration field may be greater than the duration required to transmit the MU-RTS frame. As shown in Figure 10B, a non-legacy STA1016 sets its NAV to the duration indicated by the duration field of the MU-RTS frame, over a duration from time t2 to t7. In some other implementations, a non-legacy STA1016 may set its NAV to the duration indicated by the duration field of the CTS frame.

[0116]

[0136] In some implementations, a low-latency STA may be configured to ignore the duration field of the MU-RTS frame sent by the AP at the start of the limited TWT SP. Therefore, the low-latency STA 1014 does not set its NAV according to the duration field of the MU-RTS frame. Instead, the low-latency STA 1014 may begin competing for media access immediately after the transmission of the CTS. As shown in Figure 10B, the low-latency STA 1014 senses that the media is idle during the AIFS duration from time t4 to t5, counts down the RBO duration from time t5 to t6, and obtains a TXOP from time t6 to t8. During the TXOP, the low-latency STA 1014 may send latency-sensitive traffic to or from an AP or another STA (e.g., in peer-to-peer communication).

[0117]

[0137] At the end of the NAV duration, at time t7, the non-legacy STA1016 may compete for media access. However, the non-legacy STA1016 senses that the media is busy at time t7 due to the low-latency STA1014's TXOP. Therefore, the non-legacy STA1016 refrains from accessing the shared media for the duration of the TXOP. After the low-latency STA1014's TXOP ends, at time t8, the non-legacy STA1016 may again compete for media access. As shown in Figure 10B, the non-legacy STA1016 senses that the media is idle during the AIFS duration from time t8 to t9, and from time t9 to t 10 The RBO duration is counted down until time t 10 from t 11 Get TXOP up to this point.

[0118]

[0138] In some implementations, MU-RTS may identify multiple low-latency STAs (not shown for brevity). In such implementations, each low-latency STA may transmit its respective CTS frame from time t3 to t4, depending on the MU-RTS frame. As a result, non-legacy STAs 1016 may postpone their media access for an even longer period (as explained with reference to Figures 5-7). For example, since data traffic associated with a low-latency STA may be assigned to a higher priority AC than data traffic associated with a non-member STA, the low-latency STA is more likely to win media access over a non-member STA during a given competition period.

[0119]

[0139] In some implementations, membership in a restricted TWT SP may be limited so that each low-latency STA associated with the SP has a greater chance of acquiring a TXOP in a relatively short time. For example, referring to Figure 10B, if membership in a restricted TWT SP is limited to 2, any additional low-latency STA in the BSS may be assigned to a different restricted TWT SP.

[0120]

[0140] In some implementations, the NAV duration, indicated by the duration field of the CTS frame to itself, can be chosen to balance media utilization efficiency with latency gain for latency-sensitive traffic. In the example in Figure 10B, the NAV duration is configured to terminate before the termination of a single TXOP. However, in some other implementations, the NAV duration may be configured to span one or more TXOPs.

[0121]

[0141] Figure 11A shows a timing diagram 1100 illustrating an example of wireless communication between devices belonging to a BSS. In the example in Figure 11A, the BSS is shown to include AP1102, low-latency STA1104, and non-legacy STA1106. Low-latency STA1104 operates from time t1 to t 12STA1106 is a member of the limited TWT SP (r-TWT SP) for a duration up to a certain point, while the non-legacy STA1106 is not a member of the limited TWT SP. In some implementations, AP1102 may be an example of AP110 in Figure 1 or AP300 in Figure 3. In some implementations, each of STA1104 and 1106 may be an example of either STA120a-120i in Figure 1 or STA200 in Figure 2. Although only one low-latency STA and one non-legacy STA are shown in the example in Figure 11A, in actual implementations, the BSS may include any number of low-latency STAs and any number of non-legacy STAs.

[0122]

[0142] In some implementations, AP1102 may transmit an MU-RTS frame over the shared wireless medium when the limited TWT SP begins. More specifically, AP1102 attempts to time the transmission of the MU-RTS frame to coincide with the start of the limited TWT SP. In the example in Figure 11A, the non-legacy STA1106 counts down its RBO duration before the start of the limited TWT SP. Thus, AP1102 senses that the medium is idle for the PIFS duration from time t0 to t1 and proceeds to transmit an MU-RTS frame at time t1. In some implementations, the MU-RTS frame may identify one or more low-latency STAs (such as the low-latency STA1104). As shown in Figure 11A, the low-latency STA1104 responds to the MU-RTS at time t3 by sending a CTS back to AP1102.

[0123]

[0143] In some implementations, the duration field (in the MAC header) of the MU-RTS frame may be used to protect latency-sensitive traffic in a limited TWT SP. As illustrated with reference to Figure 8A, an STA compliant with existing versions of the IEEE 802.11 standard must postpone media access for at least the duration indicated by the duration field. In some implementations, the duration indicated by the duration field may be greater than the duration required to transmit the MU-RTS frame. As shown in Figure 11A, a non-legacy STA1106 sets its NAV to the duration indicated by the duration field of the MU-RTS frame, over a duration from time t2 to t8. In some other implementations, a non-legacy STA1106 may set its NAV to the duration indicated by the duration field of the CTS frame.

[0124]

[0144] In some implementations, AP1102 may send a trigger frame at time t5 following the reception of the CTS frame. In some implementations, the trigger frame may request TB PPDU from one or more low-latency STAs (such as low-latency STA1104). As shown in Figure 11A, low-latency STA904 responds to the trigger frame at time t7 by sending UL data with TB PPDU to AP1102.

[0125]

[0145] At the end of the NAV duration, at time t8, the non-legacy STA1106 may compete for media access. However, at time t8, the non-legacy STA1106 senses that the media is busy due to the transmission of the TB PPDU. Therefore, the non-legacy STA1106 refrains from accessing the shared media for the duration of the TB PPDU. After the transmission of the TB PPDU is complete, at time t9, the non-legacy STA1106 may again compete for media access. As shown in Figure 11A, the non-legacy STA1106 from time t9 to t 10During the AIFS duration, the system senses that the medium is idle, and time t 10 from t 11 The RBO duration is counted down until time t 11 from t 12 Get TXOP up to this point.

[0126]

[0146] In some implementations, MU-RTS may identify multiple low-latency STAs (not shown for brevity). In such implementations, each low-latency STA may transmit its respective CTS frame from time t3 to t4, depending on the MU-RTS frame. In some implementations, a trigger frame may be used to request TB PPDU from multiple low-latency STAs (not shown for brevity). In such implementations, multiple low-latency STAs may simultaneously transmit their respective UL data to AP1102 with TB PPDU (from time t7 to t9).

[0127]

[0147] In some implementations, AP1102 may poll low-latency STAs before the start of a limited TWT SP to determine which of the STAs (if any) has the UL data to send. For example, AP1102 may send a BSRP trigger frame to the low-latency STA associated with the limited TWT SP. Each low-latency STA responds to the BSRP trigger frame by sending a BSR back to AP1102 indicating the amount of UL data buffered by the STA. AP1102 may use the information carried in each BSR to determine resource allocation for TB PPDU.

[0128]

[0148] In some implementations, the NAV duration, indicated by the MU-RTS frame duration field, may be chosen to balance media utilization efficiency with latency gain for latency-sensitive traffic. In the example in Figure 11A, the NAV duration is configured to end before the TB PPDU ends. However, in some other implementations, the NAV duration may be configured to extend beyond the duration of the TB PPDU.

[0129]

[0149] Figure 11B shows a timing diagram 1110 illustrating an example of wireless communication between devices belonging to a BSS. In the example in Figure 11B, the BSS is shown to include AP1112, low-latency STA1114, and non-legacy STA1116. Low-latency STA1114 operates from time t0 to t 12 STA1116 is a member of the limited TWT SP (r-TWT SP) for a duration up to a certain point, while the non-legacy STA1116 is not a member of the limited TWT SP. In some implementations, AP1112 may be an example of AP110 in Figure 1 or AP300 in Figure 3. In some implementations, each of STA1114 and 1116 may be an example of either STA120a-120i in Figure 1 or STA200 in Figure 2. Although only one low-latency STA and one non-legacy STA are shown in the example in Figure 11B, in actual implementations, the BSS may include any number of low-latency STAs and any number of non-legacy STAs.

[0130]

[0150] In some implementations, AP1112 may transmit a MU-RTS frame over the shared wireless medium when the limited TWT SP begins. More specifically, AP1112 attempts to time the transmission of the MU-RTS frame to coincide with the start of the limited TWT SP. In the example in Figure 11B, the non-legacy STA1116 receives a shortened TXOP before the start of the limited TWT SP. AP1112 senses that the medium is idle during the PIFS duration from time t0 to t1 and proceeds to transmit a MU-RTS frame at time t1. In some implementations, the MU-RTS frame may identify one or more low-latency STAs (such as low-latency STA1114). As shown in Figure 11B, low-latency STA1114 responds to the MU-RTS at time t3 by sending a CTS back to AP1112.

[0131]

[0151] In some implementations, the duration field (in the MAC header) of the MU-RTS frame may be used to protect latency-sensitive traffic in a limited TWT SP. As illustrated with reference to Figure 8A, an STA compliant with existing versions of the IEEE 802.11 standard must postpone media access for at least the duration indicated by the duration field. In some implementations, the duration indicated by the duration field may be greater than the duration required to transmit the MU-RTS frame. As shown in Figure 11B, a non-legacy STA1116 sets its NAV to the duration indicated by the duration field of the MU-RTS frame, over a duration from time t2 to t8. In some other implementations, a non-legacy STA1116 may set its NAV to the duration indicated by the duration field of the CTS frame.

[0132]

[0152] In some implementations, AP1112 may send a trigger frame at time t5 following the reception of the CTS frame. In some implementations, the trigger frame may request TB PPDU from one or more low-latency STAs (such as low-latency STA1114). As shown in Figure 11B, low-latency STA904 responds to the trigger frame at time t7 by sending UL data with TB PPDU to AP1112.

[0133]

[0153] At the end of the NAV duration, at time t8, the non-legacy STA1116 may compete for media access. However, at time t8, the non-legacy STA1116 senses that the media is busy due to the transmission of the TB PPDU. Therefore, the non-legacy STA1116 refrains from accessing the shared media for the duration of the TB PPDU. After the transmission of the TB PPDU is complete, at time t9, the non-legacy STA1116 may again compete for media access. As shown in Figure 11B, the non-legacy STA1116 from time t9 to t 10 During the AIFS duration, the system senses that the medium is idle, and time t 10 from t 11 The RBO duration is counted down until time t 11 from t 12 Get TXOP up to this point.

[0134]

[0154] In some implementations, MU-RTS may identify multiple low-latency STAs (not shown for brevity). In such implementations, each low-latency STA may transmit its respective CTS frame from time t3 to t4, depending on the MU-RTS frame. In some implementations, a trigger frame may be used to request TB PPDU from multiple low-latency STAs (not shown for brevity). In such implementations, multiple low-latency STAs may simultaneously transmit their respective UL data to AP1112 with TB PPDU (from time t7 to t9).

[0135]

[0155] In some implementations, AP1112 may poll low-latency STAs before the start of a limited TWT SP to determine which of the STAs (if any) has the UL data to send. For example, AP1112 may send a BSRP trigger frame to the low-latency STA associated with the limited TWT SP. Each low-latency STA responds to the BSRP trigger frame by sending a BSR back to AP1112 indicating the amount of UL data buffered by the STA. AP1112 may use the information carried in each BSR to determine resource allocation for TB PPDU.

[0136]

[0156] In some implementations, the NAV duration, indicated by the MU-RTS frame duration field, may be chosen to balance media utilization efficiency with latency gain for latency-sensitive traffic. In the example in Figure 11B, the NAV duration is configured to end before the TB PPDU ends. However, in some other implementations, the NAV duration may be configured to extend beyond the TB PPDU duration.

[0137]

[0157] Figure 12 shows an illustrative flowchart 1200 illustrating exemplary wireless communication operation. The exemplary operation 1200 can be performed by a wireless communication device such as either AP110 or AP300 in Figures 1 and 3, respectively.

[0138]

[0158] The wireless communication device performs a channel sensing operation to indicate whether the wireless channel is busy or idle (1202). The wireless communication device further transmits a first packet over the wireless channel in response to the channel sensing operation indicating that the wireless channel associated with the limited TWT SP is idle for a threshold duration for the initiation of the limited TWT SP during a first time, the first packet including a duration field indicating the duration for which the wireless channel is reserved, and the channel sensing operation further indicates that the wireless channel is busy during a second time, less than the duration indicated by the duration field of the first packet after the first time (1204).

[0139]

[0159] In some implementations, the wireless communication device may, in a third time, receive a third packet from the second STA via the wireless channel, the third time occurring after the second time and before the end of the limited TWT SP. In some implementations, the first time may coincide with the start of the limited TWT SP. In some implementations, the duration indicated by the duration field of the first packet may be greater than the duration required to complete the transmission of the first packet. In some implementations, the threshold duration may be the PIFS duration. In some implementations, the duration between the first time and the start of the limited TWT SP may be less than or equal to the threshold duration. In some implementations, the first packet may be a self-transmittable CTS frame.

[0140]

[0160] In some implementations, the wireless communication device may further receive a second packet via the wireless channel from a first STA associated with a limited TWT SP at a second time. In some implementations, the first packet may be an MU-RTS frame and the second packet may be a CTS frame. In some other implementations, the first packet may be a trigger frame requesting first uplink data from the first STA, and the second packet may be a TB PPDU carrying the first uplink data. In some implementations, the trigger frame may further request second uplink data from a second STA associated with a limited TWT SP, and the TB PPDU may further carry the second uplink data. In some implementations, the wireless communication device may further send a BSRP trigger frame to the first STA before the initiation of the limited TWT SP, and in response to the BSRP trigger frame, it may receive a BSR from the first STA, which indicates the availability of first uplink data.

[0141]

[0161] Figure 13 shows an illustrative flowchart 1300 illustrating exemplary wireless communication operation. Exemplary operation 1300 can be performed by a wireless communication device such as STA120a-120i in Figure 1 or STA200 in Figure 2.

[0142]

[0162] The wireless communication device receives a first packet via the wireless channel associated with the limited TWT SP at a first time, which includes a duration field indicating the duration for which the wireless channel is reserved (1302). In some implementations, the first time may coincide with the start of the limited TWT SP. In some implementations, the duration indicated by the duration field of the first packet may be greater than the duration required to complete the transmission of the first packet. In some implementations, the duration between the first time and the start of the limited TWT SP may be less than or equal to the PIFS duration. In some implementations, the first packet may be a CTS frame directed to itself.

[0143]

[0163] The wireless communication device further transmits a second packet over the wireless channel in response to the first packet at a second time, the second time being less than the duration indicated by the duration field of the first packet after the first time (1304). In some implementations, the second packet may be transmitted to the AP. In some other implementations, the second packet may be transmitted to the STA. In some implementations, the first packet may be a MU-RTS frame and the second packet may be a CTS frame. In some other implementations, the first packet may be a trigger frame requesting uplink data from the wireless communication device and the second packet may be a TB PPDU carrying the uplink data. In some implementations, the wireless communication device may further receive a BSRP trigger frame before the initiation of a limited TWT SP and transmit a BSR in response to the BSRP trigger frame, the BSR indicating the availability of uplink data.

[0144]

[0164] Figure 14 shows a block diagram of an exemplary wireless communication device 1400. In some implementations, the wireless communication device 1400 may be configured to perform the process 1200 described above with reference to Figure 12. The wireless communication device 1400 may be an exemplary implementation of either AP110 or AP300 in Figures 1 and 3, respectively. More specifically, the wireless communication device 1400 may be a package or device including a chip, SoC, chipset, at least one processor and at least one modem (e.g., a Wi-Fi (IEEE 802.11) modem or a cellular modem).

[0145]

[0165] The wireless communication device 1400 includes a receiving component 1410, a communication manager 1420, and a transmitting component 1430. The communication manager 1420 further includes a channel sensing component 1422 and a latency-sensitive (LS) traffic protection component 1424. One or more parts of components 1422-1424 may be implemented at least partially in hardware or firmware. In some implementations, at least one or more of components 1422 or 1424 are implemented at least partially as software stored in memory (such as memory 240 in Figure 2 or memory 330 in Figure 3). For example, one or more parts of components 1422 and 1424 may be implemented as non-transient instructions (or "code") that can be executed by a processor (such as processor 320 in Figure 3) to perform the function or operation of each component.

[0146]

[0166] The receiving component 1410 is configured to receive RX signals from one or more other wireless communication devices, and the transmitting component 1430 is configured to transmit TX signals to one or more other wireless communication devices. The communication manager 1420 is configured to manage wireless communication with one or more other wireless communication devices. In some implementations, the channel sensing component 1422 may perform a channel sensing operation indicating whether a wireless channel is busy or idle, and the LS traffic protection component 1424 may, in response to the channel sensing operation indicating that the wireless channel associated with the limited TWT SP is idle for a threshold duration for the initiation of the limited TWT SP in a first time, send a first packet over the wireless channel, the first packet including a duration field indicating the duration for which the wireless channel is reserved, and the channel sensing operation further indicates that the wireless channel is busy in a second time, less than the duration indicated by the duration field of the first packet, after the first time.

[0147]

[0167] Figure 15 shows a block diagram of an exemplary wireless communication device 1500. In some implementations, the wireless communication device 1500 may be configured to perform the process 1300 described above with reference to Figure 13. The wireless communication device 1500 may be an exemplary implementation of any of the STA120a-120i in Figure 1 or the STA200 in Figure 2. More specifically, the wireless communication device 1500 may be a package or device including a chip, SoC, chipset, at least one processor and at least one modem (e.g., a Wi-Fi (IEEE 802.11) modem or a cellular modem).

[0148]

[0168] The wireless communication device 1500 includes a receiving component 1510, a communication manager 1520, and a transmitting component 1530. The communication manager 1520 further includes a latency-sensitive (LS) traffic management component 1522. The portion of the LS traffic management component 1522 may be implemented at least partially in hardware or firmware. In some implementations, the LS traffic management component 1522 is implemented at least partially as software stored in memory (such as memory 240 in Figure 2 or memory 330 in Figure 3). For example, the portion of the LS traffic management component 1522 may be implemented as non-transient instructions (or "code") that can be executed by a processor (such as processor 220 in Figure 2) to perform the function or operation of each component.

[0149]

[0169] The receiving component 1510 is configured to receive an RX signal from one or more other wireless communication devices, and the transmitting component 1530 is configured to transmit a TX signal to one or more other wireless communication devices. In some implementations, the receiving component 1510 may, at a first time, receive a first packet via the wireless channel associated with the limited TWT SP, which includes a duration field indicating the duration for which the wireless channel is reserved. In some implementations, the transmitting component 1530 may, at a second time, transmit a second packet via the wireless channel in response to the first packet, which is less than the duration indicated by the duration field of the first packet after the first time.

[0150]

[0170] Implementation examples are described in the following numbered clauses. 1. A method for wireless communication using a wireless communication device, Perform channel sensing operations to indicate whether a wireless channel is busy or idle, A method comprising: transmitting a first packet over a wireless channel in response to a channel sensing operation indicating that the wireless channel associated with a limited target wake time (TWT) SP is idle for a threshold duration for the start of the limited target wake time (TWT) SP during a first time period, wherein the first packet includes a duration field indicating the duration for which the wireless channel is reserved, and the channel sensing operation further indicates that the wireless channel is busy for a second time period less than the duration indicated by the duration field of the first packet after the first time period. 2. The first time is as described in Clause 1, coinciding with the commencement of the Limited TWT SP. 3. The duration indicated by the duration field of the first packet is greater than the duration required to complete the transmission of the first packet, as described in Clause 1 or 2. 4. The threshold duration is the point coordination function (PCF) interframe space (PIFS) duration, as described in any one of clauses 1 to 3. 5. The duration between the first time and the start of the limited TWT SP is less than or equal to the threshold duration, as described in any one of clauses 1 to 4. 6. The method described in any one of the clauses 1 to 5, further comprising receiving a second packet via a wireless channel from a first wireless station (STA) associated with a limited TWT SP during a second time. 7. The first packet comprises a self-transmittable (CTS) frame, as described in any one of clauses 1 to 6. 8. The method according to any one of the clauses 1 to 6, wherein the first packet comprises a multi-user (MU) transmission request (RTS) frame and the second packet comprises a CTS frame. 9. The method according to any one of the clauses 1 to 6, wherein the first packet comprises a trigger frame requesting first uplink data from a first STA, and the second packet is a trigger-based (TB) physical layer convergence protocol (PLCP) protocol data unit (PPDU) carrying the first uplink data. 10. The method described in any one of the clauses 1-6 or 9, wherein the trigger frame further requests second uplink data from the second STA associated with the limited TWT SP, and the TB PPDU further carries the second uplink data. 11. Before initiating the limited TWT SP, send a buffer status report poll (BSRP) trigger frame to the first STA, The method according to any one of the clauses 1-6, 9, or 10, further comprising receiving a buffer status report (BSR) from a first STA in response to a BSRP trigger frame, wherein the BSR indicates the availability of first uplink data. 12. The method described in any one of the clauses 1 to 11, further comprising receiving a third packet via a wireless channel from the second STA during the third time, wherein the third time occurs after the second time and before the termination of the limited TWT SP. 13. Wireless communication device, A processing system configured to perform channel sensing operations that indicate whether a wireless channel is busy or idle, A wireless communications device comprising at least one interface, the at least one interface being configured to transmit a first packet over a wireless channel in response to a channel sensing operation indicating that, in a first time, the wireless channel associated with a limited target wake time (TWT) SP is idle for a threshold duration relative to the start of the TWT SP, the first packet including a duration field indicating the duration for which the wireless channel is reserved, and the channel sensing operation further indicating that the wireless channel is busy in a second time only less than the duration indicated by the duration field of the first packet after the first time. 14. The first packet comprises a self-transmittable (CTS) frame, as described in Clause 13, for the wireless communications device. 15. The wireless communications device according to Clause 13, wherein at least one interface is further configured to receive a second packet via a wireless channel from a wireless station (STA) associated with a limited TWT SP in a second time, the first packet comprising a multi-user (MU) request to transmit (RTS) frame and the second packet comprising a CTS frame. 16. The wireless communications device according to Clause 13, wherein at least one interface is further configured to receive a second packet via a wireless channel from an STA associated with a limited TWT SP in a second time, the first packet comprising a trigger frame requesting uplink data from the STA, and the second packet being a trigger-based (TB) physical layer convergence protocol (PLCP) protocol data unit (PPDU) carrying uplink data. 17. A method performed by a wireless communication device, In the first time period, a first packet is received via a wireless channel associated with a limited target wake time (TWT) service period (SP), which includes a duration field indicating the duration for which the wireless channel is reserved. A method comprising, in a second time period, transmitting a second packet via a wireless channel in response to a first packet, the second packet being less than the duration indicated by the duration field of the first packet after the first time period. 18. The first time is as described in Clause 17, coinciding with the commencement of the Limited TWT SP. 19. The duration indicated by the duration field of the first packet is greater than the duration required to complete the transmission of the first packet, as described in Clause 17 or 18. 20. The duration between the first time and the start of the limited TWT SP is less than or equal to the point adjustment function (PCF) inter-frame space (PIFS) duration, as described in any one of clauses 17 to 19. 21. The method described in any one of the clauses 17-20, wherein the first packet comprises a self-transmittable (CTS) frame. 22. The method according to any one of the clauses 17 to 20, wherein the first packet comprises a multi-user (MU) transmission request (RTS) frame and the second packet comprises a CTS frame. 23. The method according to any one of the clauses 17 to 20, wherein the first packet comprises a trigger frame requesting uplink data from a wireless communication device, and the second packet is a trigger-based (TB) physical layer convergence protocol (PLCP) protocol data unit (PPDU) carrying the uplink data. 24. Receiving a Buffer Status Report Pole (BSRP) trigger frame before initiating a Limited TWT SP, The method of any one of the clauses 17-20 or 23, further comprising sending a Buffer Status Report (BSR) indicating the availability of uplink data in response to a BSRP trigger frame. 25. The second packet is sent to the access point (AP) as described in any one of clauses 17-24. 26. The second packet is transmitted to the wireless station (STA) in the manner described in any one of clauses 17-24. 27. Wireless communication device, Processing system and, It has an interface, and the interface is In the first time period, a first packet is received via a wireless channel associated with a Limited Target Wake Time (TWT) service period (SP), which includes a duration field indicating the duration for which the wireless channel is reserved, and A wireless communication device configured to, in a second time period, transmit a second packet via a wireless channel in response to a first packet, which is less than the duration indicated by the duration field of the first packet, after the first time period. 28. The first packet comprises a self-transmittable (CTS) frame, as described in Clause 27, for the wireless communications device. 29. A wireless communications device as described in Clause 27, wherein the first packet comprises a Multi-User (MU) Request to Send (RTS) frame and the second packet comprises a CTS frame. 30. A wireless communication device as described in Clause 27, wherein the first packet comprises a trigger frame requesting uplink data from the wireless communication device, and the second packet is a trigger-based (TB) physical layer convergence protocol (PLCP) protocol data unit (PPDU) carrying the uplink data.

[0151]

[0171] Where used herein, the phrases referring to “at least one of” or “one or more of” the list of items refer to any combination of those items that includes a single member. For example, “at least one of a, b, or c” is intended to include the possibilities of a only, b only, c only, a and b combination, a and c combination, b and c combination, and a, b, and c combination.

[0152]

[0172] The various exemplary components, logic, logic blocks, modules, circuits, operations, and algorithmic processes described herein with respect to the implementation forms disclosed herein may be implemented as electronic hardware, firmware, software, or combinations of hardware, firmware, or software, including the structures disclosed herein and their structural equivalents. The compatibility of hardware, firmware, and software is described conceptually in terms of functionality and is shown above for the various exemplary components, blocks, modules, circuits, and processes described herein. Whether such functionality is implemented in hardware, firmware, or software depends on the specific application and the design constraints imposed on the overall system.

[0153]

[0173] Various modifications of the implementations described herein may be readily apparent to those skilled in the art, and the general principles defined herein may be applied to other implementations without departing from the spirit or scope of this disclosure. Accordingly, the claims should not be limited to the implementations shown herein, but should be given the broadest scope consistent with this disclosure, the principles disclosed herein, and the novel features.

[0154]

[0174] Furthermore, various features described herein in the context of separate implementations may also be implemented in combination in a single implementation. Conversely, various features described in the context of a single implementation may also be implemented separately in multiple implementations or in any suitable partial combination. Thus, features are described above as working in a particular combination and may even be initially claimed as such, but in some cases one or more features may be removed from the claimed combination, and the claimed combination may cover partial combinations or variations of partial combinations.

[0155]

[0175] Similarly, while operations are shown in a specific order in the diagrams, this should not be understood as requiring that such operations be performed in a specific or sequential order shown, or that all illustrated operations be performed, in order to achieve the desired result. Furthermore, diagrams may schematically illustrate one or more exemplary processes in the form of flowcharts or flow diagrams. However, other operations not shown may be incorporated into the schematically illustrated exemplary processes. For example, one or more additional operations may be performed before, after, simultaneously with, or in between any of the illustrated operations. In some situations, multitasking and parallel processing may be advantageous. Moreover, the separation of various system components in the implementation forms described above should not be understood as requiring such separation in all implementation forms, and it should be understood that the described program components and systems can generally be integrated together in a single software product or packaged into multiple software products. The invention described in the original claims of this application is listed below. [C1] A method performed by a wireless communication device, Performing a channel sensing operation to indicate whether the wireless channel is busy or idle, A method comprising: transmitting a first packet over a wireless channel in response to the channel sensing operation indicating that the wireless channel associated with the limited target wake time (TWT) SP is idle for a threshold duration for the start of the limited target wake time (TWT) SP, wherein the first packet includes a duration field indicating the duration for which the wireless channel is reserved, and the channel sensing operation further indicates that the wireless channel is busy for less than the duration indicated by the duration field of the first packet in a second time after the first time. [C2] The method according to C1, wherein the first time coincides with the start of the limited TWT SP. [C3] The method of C1, wherein the duration indicated by the duration field of the first packet is greater than the duration required to complete the transmission of the first packet. [C4] The method according to C1, wherein the threshold duration is the point adjustment function (PCF) interframe space (PIFS) duration. [C5] The method according to C1, wherein the duration between the first time and the start of the limited TWT SP is less than or equal to the threshold duration. [C6] The method of C1, wherein the first packet comprises a self-transmittable (CTS) frame. [C7] The method of C1, further comprising receiving a second packet via the wireless channel from a first wireless station (STA) associated with the limited TWT SP during the second time. [C8] The method according to C7, wherein the first packet comprises a multi-user (MU) request to send (RTS) frame and the second packet comprises a CTS frame. [C9] The method according to C7, wherein the first packet comprises a trigger frame requesting first uplink data from the first STA, and the second packet is a trigger-based (TB) physical layer convergence protocol (PLCP) protocol data unit (PPDU) carrying the first uplink data. [C10] The method according to C9, wherein the trigger frame further requests second uplink data from a second STA associated with the limited TWT SP, and the TB PPDU further carries the second uplink data. [C11] Before the start of the limited TWT SP, a buffer status report pole (BSRP) trigger frame is sent to the first STA, The method of C9, further comprising receiving a buffer status report (BSR) from the first STA in response to the BSRP trigger frame, wherein the BSR indicates the availability of the first uplink data. [C12] The method of C1, further comprising receiving a third packet from a second STA via the wireless channel during a third time, wherein the third time occurs after the second time and before the termination of the limited TWT SP. [C13] Wireless communication device, A processing system configured to perform channel sensing operations to indicate whether the wireless channel is busy or idle, A wireless communications device comprising at least one interface, wherein the at least one interface is configured to transmit a first packet over the wireless channel in response to the channel sensing operation indicating that the wireless channel associated with the Limited Target Wake Time (TWT) SP is idle for a threshold duration for the start of the Limited Target Wake Time (TWT) SP during a first time, the first packet includes a duration field indicating the duration for which the wireless channel is reserved, and the channel sensing operation further indicates that the wireless channel is busy for a second time after the first time by less than the duration indicated by the duration field of the first packet. [C14] The wireless communication device described in C13, wherein the first packet comprises a transmittable to itself (CTS) frame. [C15] The wireless communication device according to C13, wherein the at least one interface is further configured to receive a second packet via the wireless channel from a wireless station (STA) associated with the limited TWT SP in the second time, the first packet comprising a multi-user (MU) request to transmit (RTS) frame, and the second packet comprising a CTS frame. [C16] The wireless communication device according to C13, wherein the at least one interface is further configured to receive a second packet via the wireless channel from an STA associated with the limited TWT SP in the second time, the first packet comprising a trigger frame requesting uplink data from the STA, and the second packet being a trigger-based (TB) physical layer convergence protocol (PLCP) protocol data unit (PPDU) carrying the uplink data. [C17] A method performed by a wireless communication device, In a first time period, a first packet is received via a wireless channel associated with a limited target wake time (TWT) service period (SP), and the first packet includes a duration field indicating the duration for which the wireless channel is reserved. A method comprising transmitting a second packet via the wireless channel in response to the first packet at a second time, wherein the second time is less than the duration indicated by the duration field of the first packet after the first time. [C18] The method according to C17, wherein the first time coincides with the start of the limited TWT SP. [C19] The method of C17, wherein the duration indicated by the duration field of the first packet is greater than the duration required to complete the transmission of the first packet. [C20] The method according to C17, wherein the duration between the first time and the start of the limited TWT SP is less than or equal to the point adjustment function (PCF) inter-frame space (PIFS) duration. [C21] The method of C17, wherein the first packet comprises a self-transmittable (CTS) frame. [C22] The method according to C17, wherein the first packet comprises a multi-user (MU) request to send (RTS) frame, and the second packet comprises a CTS frame. [C23] The method according to C17, wherein the first packet comprises a trigger frame requesting uplink data from the wireless communication device, and the second packet is a trigger-based (TB) physical layer convergence protocol (PLCP) protocol data unit (PPDU) carrying the uplink data. [C24] Receiving a Buffer Status Report Pole (BSRP) trigger frame before the start of the limited TWT SP, The method of C23, further comprising sending a buffer status report (BSR) in response to the BSRP trigger frame, wherein the BSR indicates the availability of the uplink data. [C25] The second packet described above is sent to the access point (AP) in the manner described in C17. [C26] The second packet is transmitted to the wireless station (STA) in the manner described in C17. [C27] Wireless communication device, Processing system and, It comprises an interface, and the interface is In a first time period, a first packet is received via a wireless channel associated with a limited target wake time (TWT) service period (SP), and the first packet includes a duration field indicating the duration for which the wireless channel is reserved. In a second time period, in response to the first packet, a second packet is transmitted via the wireless channel, and the second time period is less than the duration indicated by the duration field of the first packet, A wireless communication device configured to perform the following actions. [C28] The wireless communications device described in C27, wherein the first packet comprises a transmittable to itself (CTS) frame. [C29] The wireless communication device according to C27, wherein the first packet comprises a multi-user (MU) request to transmit (RTS) frame, and the second packet comprises a CTS frame. [C30] The wireless communication device according to C27, wherein the first packet comprises a trigger frame requesting uplink data from the wireless communication device, and the second packet is a trigger-based (TB) physical layer convergence protocol (PLCP) protocol data unit (PPDU) carrying the uplink data.

Claims

1. A method performed by a wireless communication device, Perform channel sensing operations to indicate whether a wireless channel is busy or idle, A method comprising: transmitting a first packet over a wireless channel in response to the channel sensing operation indicating that the wireless channel associated with the Limited Target Wake Time (TWT) SP is idle during a threshold duration for the start of the Limited Target Wake Time (TWT) SP, wherein the first packet includes a duration field indicating the duration for which the wireless channel is reserved, the duration corresponding to a first portion of the Limited Target Wake Time SP, and a second portion of the Limited Target Wake Time SP following the first portion being available for competition by any one of one or more first devices that are members of the Limited Target Wake Time SP and one or more second devices that are not members of the Limited Target Wake Time SP.

2. The method according to claim 1, wherein the first time coincides with the start of the limited TWT SP.

3. The method according to claim 1, wherein the duration indicated by the duration field of the first packet is greater than a third duration required to complete the transmission of the first packet.

4. The method according to claim 1, wherein the threshold duration is the point adjustment function (PCF) inter-frame space (PIFS) duration.

5. The method according to claim 1, wherein the third duration between the first time and the start of the limited TWT SP is less than or equal to the threshold duration.

6. The method according to claim 1, wherein the first packet comprises a self-transmittable (CTS) frame.

7. The method according to claim 1, further comprising receiving a second packet via the wireless channel from a first wireless station (STA) associated with the restricted TWT SP at a second time.

8. The method according to claim 7, wherein the first packet comprises a multi-user (MU) transmit request (RTS) frame, and the second packet comprises a CTS frame.

9. The method according to claim 7, wherein the first packet comprises a trigger frame requesting first uplink data from the first STA, and the second packet is a trigger-based (TB) physical layer convergence protocol (PLCP) protocol data unit (PPDU) carrying the first uplink data.

10. The method according to claim 1, further comprising receiving a third packet from the second STA via the wireless channel during a third time, wherein the third time occurs after the second time and before the termination of the limited TWT SP.

11. The method according to claim 1, further comprising transmitting a quiescence element indicating a quiescence duration for the initiation of the restricted TWT SP, wherein the quiescence element indicates that during the quiescence duration, one or more second devices that are not members of the restricted TWT SP are restricted from competing for access to the wireless channel.

12. A wireless communication device, A processing system comprising one or more processors, the processing system configured to perform channel sensing operations to indicate whether a wireless channel is busy or idle, A wireless communications device comprising at least one interface, wherein the at least one interface is configured to transmit a first packet over the wireless channel in response to the channel sensing operation indicating that the wireless channel associated with the Limited Target Wake Time (TWT) SP is idle for a threshold duration for the start of the Limited Target Wake Time (TWT) SP, the first packet including a duration field indicating the duration for which the wireless channel is reserved, the duration corresponding to a first portion of the Limited Target Wake Time SP, and a second portion of the Limited Target Wake Time SP following the first portion being available for competition by any one of one or more first devices that are members of the Limited Target Wake Time SP and one or more second devices that are not members of the Limited Target Wake Time SP.

13. The wireless communication device according to claim 12, wherein the first packet comprises a self-transmittable (CTS) frame.

14. The wireless communication device according to claim 12, wherein the at least one interface is further configured to receive a second packet via the wireless channel from a wireless station (STA) associated with the restricted TWT SP in a second time, the first packet comprising a multi-user (MU) request to transmit (RTS) frame, and the second packet comprising a CTS frame.

15. The wireless communication device according to claim 12, wherein the at least one interface is further configured to receive a second packet via the wireless channel from an STA associated with the restricted TWT SP in a second time, the first packet comprising a trigger frame requesting uplink data from the STA, and the second packet being a trigger-based (TB) physical layer convergence protocol (PLCP) protocol data unit (PPDU) carrying the uplink data.

16. A method performed by a wireless communication device, In a first time period, a first packet is received over a wireless channel associated with a Limited Target Wake Time (TWT) Service Period (SP), the first packet including a duration field indicating the duration for which the wireless channel is reserved, the duration corresponding to a first portion of the Limited TWT SP, and a second portion of the Limited TWT SP following the first portion is available for competition by any one of the following: one or more first devices that are members of the Limited TWT SP, and one or more second devices that are not members of the Limited TWT SP. A method comprising: transmitting a second packet via the wireless channel in response to the first packet during a second time period, wherein the second time period occurs between the first portion of the restricted TWT SP, at least on the basis that the wireless communication device is a member of the restricted TWT SP.

17. The method according to claim 16, wherein the first time coincides with the start of the limited TWT SP.

18. The method according to claim 16, wherein the duration indicated by the duration field of the first packet is greater than a third duration required to complete the transmission of the first packet.

19. The method according to claim 16, wherein the third duration between the first time and the start of the limited TWT SP is less than or equal to the point adjustment function (PCF) interframe space (PIFS) duration.

20. The method according to claim 16, wherein the first packet comprises a self-transmittable (CTS) frame.

21. The method according to claim 16, wherein the first packet comprises a multi-user (MU) transmission request (RTS) frame, and the second packet comprises a CTS frame.

22. The method according to claim 16, wherein the first packet comprises a trigger frame requesting uplink data from the wireless communication device, and the second packet is a trigger-based (TB) physical layer convergence protocol (PLCP) protocol data unit (PPDU) carrying the uplink data.

23. Receiving a Buffer Status Report Pole (BSRP) trigger frame before the start of the limited TWT SP, The method of claim 22, further comprising transmitting a buffer status report (BSR) in response to the BSRP trigger frame, wherein the BSR indicates the availability of the uplink data.

24. The method according to claim 16, wherein the second packet is transmitted to an access point (AP).

25. The method according to claim 16, wherein the second packet is transmitted to a wireless station (STA).

26. The method of claim 16, further comprising receiving a quiescent element indicating a quiescent duration for the initiation of the restricted TWT SP, wherein the quiescent element indicates that during the quiescent duration, the one or more second devices that are not members of the restricted TWT SP are restricted from competing for access to the wireless channel.

27. A wireless communication device, A processing system comprising one or more processors, It comprises an interface, and the interface is In a first time period, a first packet is received over a wireless channel associated with a Limited Target Wake Time (TWT) Service Period (SP), the first packet including a duration field indicating the duration for which the wireless channel is reserved, the duration corresponding to a first portion of the Limited TWT SP, and a second portion of the Limited TWT SP following the first portion is available for competition by any one of the following: one or more first devices that are members of the Limited TWT SP, and one or more second devices that are not members of the Limited TWT SP. In the second time, in response to the first packet, a second packet is transmitted via the wireless channel, and the second time occurs between the first portion of the restricted TWT SP, at least in part on the basis that the wireless communication device is a member of the restricted TWT SP. A wireless communication device configured to perform the following actions.

28. The wireless communication device according to claim 27, wherein the first packet comprises a self-transmittable (CTS) frame.

29. The wireless communication device according to claim 27, wherein the first packet comprises a multi-user (MU) transmission request (RTS) frame, and the second packet comprises a CTS frame.

30. The wireless communication device according to claim 27, wherein the first packet comprises a trigger frame requesting uplink data from the wireless communication device, and the second packet is a trigger-based (TB) physical layer convergence protocol (PLCP) protocol data unit (PPDU) carrying the uplink data.

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