Traffic management in restricted target wake time (TWT) service periods

Abstract

This application provides systems, methods, and apparatus (including computer programs encoded on computer storage media) for managing data traffic during a restricted target wake-up time (TWT) service period (SP). In some embodiments, an access point (AP) may transmit a packet at the beginning of the restricted TWT SP that signals all non-member radio stations (STAs) to postpone access to the radio media for at least a threshold duration. Upon receiving the packet, any non-member STA associated with the AP may set its network allocation vector (NAV) according to the duration indicated by the duration field of the received packet. In some implementations, a low-latency STA that is a member of the TWT SP may not set its NAV according to the duration field of the received packet. Alternatively, a low-latency STA may access the radio media before the NAV associated with a non-member STA expires.

Description

[Technical Field]

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

[0002] In summary, the subject matter of this case concerns wireless communications, and more specifically, data communications during restricted target wake-up time (TWT) service periods. [Previous Technology]

[0003] A Wireless Local Area Network (WLAN) can be formed by one or more Access Points (APs) that provide a shared wireless communication medium for use by several client devices or stations (STAs). Each AP (which may correspond to a Basic Service Set (BSS)) can periodically broadcast beacon frames to enable any STA within the wireless range of the AP to establish and maintain a communication link with the WLAN. WLANs operating according to the IEEE 802.11 standard series are commonly referred to as Wi-Fi networks.

[0004] Some wireless communication devices can be associated with low-latency applications that have stringent 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 can specify various latency, throughput, and timing requirements for the wireless communication system providing connectivity for such applications. Therefore, it is desirable to ensure that the WLAN can meet the various latency, throughput, and timing requirements of such low-latency applications. [Summary of the Invention]

[0005] The systems, methods and apparatuses contained in this case have several innovative forms, none of which are solely responsible for the desired properties disclosed herein.

[0006] One innovative aspect of the subject matter described in this application can be implemented as a method of wireless communication. This method can be performed by a wireless communication device to manage data traffic during a restricted target wake-up time (TWT) service period (SP). In some implementations, the method may include the steps of: performing a channel sensing operation indicating whether a wireless channel is busy or idle; and in response to the channel sensing operation indicating that the wireless channel is idle for a threshold duration relative to the start of the restricted TWT SP, transmitting a first packet on the wireless channel associated with the restricted TWT SP at a first time, wherein the first packet includes a duration field indicating a duration reserved for the wireless channel, and wherein the channel sensing operation also indicates that the wireless channel is busy 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.

[0007] Another innovative aspect of the subject matter described in this case can be implemented in a wireless communication device. The wireless communication device may include: a processing system configured to: perform a channel sensing operation indicating whether a wireless channel is busy or idle; and at least one interface configured to: in response to the channel sensing operation indicating that the wireless channel is idle for a threshold duration relative to the start of a restricted TWT SP, transmit a first packet on the wireless channel associated with the restricted TWT SP at a first time, wherein the first packet includes a duration field indicating a duration for which the wireless channel is reserved, and wherein the channel sensing operation also indicates that the wireless channel is busy 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.

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

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

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

Implementation Method

[0033] For the purpose of describing the innovative aspects of the subject matter, the following description is directed to certain specific implementations. However, it will be readily apparent to those skilled in the art that the teachings herein can be applied in a variety of different ways. The described implementations can be implemented in any device, system, or network capable of transmitting and receiving radio frequency (RF) signals according to one or more of the following: Long Term Evolution (LTE), 3G, 4G, or 5G (New Radio (NR)) standards published by the 3GPP, the Institute of Electrical and Electronics Engineers (IEEE) 802.11 standard, the IEEE 802.15 standard, or standards such as the Bluetooth® standard defined by the Bluetooth Special Interest Group (SIG), and other standards. The described implementation can 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 methods: 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 Multiple User (MU) MIMO. The described implementation can also be implemented using other wireless communication protocols or RF signals suitable for use in one or more of the following: Wireless Wide Area Network (WWAN), Wireless Personal Area Network (WPAN), Wireless Local Area Network (WLAN), or Internet of Things (IoT) network.

[0034] Many wireless networks use random channel access mechanisms to control access to shared wireless media. In such wireless networks, wireless communication devices (including access points (APs) and radio stations (STAs)) compete with each other for access to the wireless media using carrier sense multiple access with collision avoidance (CSMA / CA) technology. Typically, the wireless communication device with the lowest backorder (RBO) randomly selected wins the media access contention operation and is allowed access to the wireless media during a period commonly referred to as a transmission 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 media.

[0035] Some random channel access mechanisms, such as Enhanced Distributed Channel Access (EDCA), provide a greater likelihood of obtaining media access for high-priority traffic than for low-priority traffic. EDCA classifies data into different access categories (ACs), such as, for example, 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 a different range of RBOs so that higher-priority data is more likely to win TXOPs than lower-priority data (e.g., by assigning a lower RBO to higher-priority data and a higher RBO to lower-priority data). Although EDCA increases the likelihood of low-latency data traffic gaining access to the shared wireless media during a given contention period, the unpredictable outcome of media access contention operations may prevent low-latency applications from achieving certain levels of throughput or meeting certain latency requirements.

[0036] The IEEE 802.11be revision of the IEEE 802.11 standard describes a constrained target wake-up time (TWT) service period (SP), which can be used to provide more predictable latency, reduced worst-case latency, or reduced signal interference, resulting in higher reliability for latency-sensitive traffic. As used herein, the term "non-traditional STA" can refer to any STA that supports constrained TWT operation, while the term "low-latency STA" can refer to any non-traditional STA that has latency-sensitive traffic to transmit or receive. Conversely, the term "traditional STA" can refer to any STA that does not support constrained TWT operation. The IEEE 802.11be revision requires all non-traditional STAs that are TXOP holders outside of a constrained TWT SP to terminate their respective TXOPs before the start of any constrained TWT SP in which they are not members. Although membership in a constrained TWT SP is reserved for low-latency STAs, the current rules regarding constrained TWT SPs do not prevent non-member STAs from acquiring TXOPs during a constrained TWT SP. Therefore, some non-member STAs can gain access to the shared radio media during restricted TWT SPs, even before members of the SP. Consequently, new communication protocols or mechanisms are needed to further protect time-sensitive traffic in restricted TWT SPs.

[0037] The implementation of the subject matter described in this case can be used to manage data traffic in a restricted TWT SP. In some embodiments, the AP can transmit a packet at the beginning of the restricted TWT SP that explicitly signals all non-member STAs that access to the wireless media will be postponed for at least a threshold duration. For example, the threshold duration can be indicated via a duration field in the Media Access Control (MAC) header of the packet. Upon receiving the packet, any non-member STA associated with the AP can set its Network Allocation Vector (NAV) based on the duration indicated via the duration field. In some implementations, the packet can be a trigger frame requesting Triggered (TB) Entity Layer Convergence Protocol (PLCP) Protocol Data Units (PPDUs) from one or more low-latency STAs. In some other implementations, the packet can be a Clear Transmission (CTS) to itself frame. In this implementation, any low-latency STA that is a member of the TWT SP can ignore the CTS to itself frame. In other words, a low-latency STA may not set its NAV according to the duration indicated in the duration field of the frame via CTS to itself. Furthermore, in some implementations, the packet can be a Multi-User (MU) Request to Transmit (RTS) frame that identifies one or more low-latency STAs. In this implementation, each low-latency STA identified by the MU-RTS can respond to the MU-RTS frame by transmitting a CTS frame without setting its NAV according to the duration field of the MU-RTS frame.

[0038] In some other configurations, non-traditional STAs that are not members of a restricted TWT SP may be required (e.g., via implicit signaling) to postpone access to the radio media at the beginning of the restricted TWT SP for at least a threshold duration. In some implementations, non-traditional STAs may be required to reset their RBO at the beginning of the restricted TWT SP. Therefore, each non-traditional STA (including low-latency STAs as members of the SP and non-member STAs) with data to send or receive at the beginning of the restricted TWT SP must contend for media access from the beginning of the restricted TWT SP. In some other implementations, non-traditional STAs may be required to postpone access to the shared radio media for the duration of the restricted TWT SP. Therefore, any non-member STA with data to send or receive during the restricted TWT SP must avoid access to the shared radio media until after the restricted TWT SP has ended. Furthermore, in some configurations, the AP may suppress traffic from all non-traditional STAs that are not members of the restricted TWT SP for at least a threshold duration at the beginning of the restricted TWT SP. For example, an AP may broadcast a beacon frame that includes a quiet element indicating the quiet duration associated with a restricted TWT SP. Upon receiving such a beacon frame, any non-member STA having data to send or receive during the restricted TWT SP must postpone access to the shared radio media for at least the quiet duration indicated in the beacon frame.

[0039] Specific implementations of the subject matter described in this application can be implemented to achieve one or more of the following potential advantages. By requiring non-member STAs to delay media access for a threshold duration at the beginning of a restricted TWT via explicit or implicit signaling, various forms of this application can significantly improve the latency gain achievable for latency-sensitive services by applying 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 beginning of a restricted TWT SP can gain access to the shared wireless media before any low-latency STA that is a member of the SP. However, the additional requirement imposed on the non-member STA (via the signaling techniques of this application) can protect low-latency STAs from losing media access at the beginning of the restricted TWT SP. Therefore, various forms of this application can ensure that latency-sensitive services take precedence over all other services during a restricted TWT SP. Consequently, a restricted TWT SP can provide more predictable latency, reduced worst-case latency, or reduced signal interference, resulting in higher reliability for latency-sensitive services.

[0040] Figure 1 illustrates a block diagram of an exemplary wireless system 100. The wireless system 100 is shown as including a wireless access point (AP) 110 and several wireless stations (STAs) 120a-120i. For simplicity, Figure 1 illustrates one AP 110. The AP 110 can form a wireless local area network (WLAN), which allows 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 elements (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 communication (such as in the absence of or involving AP 110). A unique MAC address, programmed in the AP 110 by, for example, the manufacturer of the access point, can be assigned to the AP 110. Similarly, a unique MAC address can be assigned to each of the STA 120a-120i.

[0041] In some implementations, the wireless system 100 may correspond to a multiple-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. Furthermore, although the WLAN is illustrated as an Infrastructure Basic Services Set (BSS) in Figure 1, in some other implementations, the WLAN may be an Independent Basic Services Set (IBSS), an Extended Services Set (ESS), an ad hoc network, or a peer-to-peer (P2P) network (such as operating according to one or more Wi-Fi Direct protocols).

[0042] STA 120a-120i can be any suitable Wi-Fi enabled wireless device, including, for example, a mobile phone, a personal digital assistant (PDA), a tablet device, a laptop computer, etc. STA 120a-120i can also be referred to as user equipment (UE), user station, mobile unit, user unit, radio unit, remote unit, mobile device, wireless device, wireless communication device, remote device, mobile user station, access terminal, mobile terminal, wireless terminal, remote terminal, handheld device, user agent, mobile service client, client, or some other suitable term.

[0043] AP 110 can be any suitable device that allows one or more wireless devices (such as STA 120a-120i) to connect to another network (such as a local area network (LAN), wide area network (WAN), metropolitan area network (MAN), or internet). In some implementations, system controller 130 can facilitate communication between AP 110 and other networks or systems. In some implementations, system controller 130 can facilitate communication between AP 110 and one or more other APs (not shown for simplicity) that can be associated with other wireless networks. Alternatively or concurrently, AP 110 can use wireless communication to exchange signals and information with one or more other APs.

[0044] AP 110 can periodically broadcast beacon frames to enable STA 120a-120i and other wireless devices within AP 110's wireless range to establish and maintain communication links with AP 110. Beacon frames are typically broadcast according to the Target Beacon Transmission Time (TBTT) schedule. The beacon frames can indicate downlink (DL) data transmissions to STA 120a-120i and request or schedule uplink (UL) data transmissions from STA 120a-120i. The broadcast beacon frames may include AP 110's Timing Synchronization Function (TSF) value. STA 120a-120i can synchronize their own local TSF value with the broadcast TSF value, for example, synchronizing all STA 120a-120i with each other and with AP 110.

[0045] In some implementations, each of the stations STA 120a-120i and AP 110 may include one or more transceivers, one or more processing resources (such as 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 simplicity) for transmitting and receiving wireless communication signals. In some implementations, each transceiver may communicate with other wireless devices in different frequency bands or using different communication protocols. Memory resources may include non-transitory computer-readable media (such as one or more non-volatile memory elements, such as EPROM, EEPROM, flash memory, hard disks, etc.) storing instructions for performing one or more operations described with respect to Figures 5-11.

[0046] Figure 2 illustrates an exemplary wireless station (STA) 200. STA 200 may be an implementation of at least one of the STAs 120a-120i of Figure 1. STA 200 may include one or more transceivers 210, a processor 220, a user interface 230, memory 240, and several antennas ANT1-ANTn. Transceivers 210 may be coupled directly to antennas ANT1-ANTn or via antenna selection circuitry (not shown for simplicity). Transceivers 210 may be used to transmit signals to and receive signals from other wireless devices, including, for example, several APs and several other STAs. Although not shown in Figure 2 for simplicity, transceivers 210 may include any number of transmission chains to process signals and transmit signals via antennas ANT1-ANTn to other wireless devices, and may include any number of receive chains to process signals received from antennas ANT1-ANTn. Therefore, STA 200 may be configured for MIMO communication and OFDMA communication. MIMO communication can include SU-MIMO and MU-MIMO communication. In some implementations, the STA 200 can use multiple antennas ANT1-ANTn to provide antenna diversity. Antenna diversity can include polarization diversity, mode diversity, and spatial diversity.

[0047] Processor 220 may be any suitable one or more processors capable of executing scripts or instructions of one or more software programs stored in STA 200 (such as in memory 240). In some implementations, processor 220 may be or include one or more microprocessors providing processor functionality and external memory providing at least a portion of machine-readable medium. In other implementations, processor 220 may be or include application-specific integrated circuits (ASICs), wherein the processor, bus interface, user interface, and at least a portion of machine-readable medium are integrated into a single chip. In some other implementations, processor 220 may be or include one or more field-programmable gate arrays (FPGAs) or programmable logic devices (PLDs).

[0048] In some implementations, processor 220 may be an element of a processing system. A processing system may generally represent a system or a series of machines or elements that receive input and process the input to produce a set of outputs (which may be passed to other systems or elements, such as STA 200). For example, the processing system of STA 200 may represent a system that includes various other elements or sub-elements of STA 200.

[0049] The processing system of STA 200 can interface with other components of STA 200 and can process information (such as inputs or signals) received from other components and output information to other components. For example, the chip or modem of STA 200 can be coupled to or include the processing system, a first interface for outputting information, and a second interface for receiving information. In some cases, the first interface can represent the interface between the processing system of the chip or modem and the transmitter, allowing STA 200 to transmit information output from the chip or modem. In some cases, the second interface can represent the interface between the processing system of the chip or modem and the receiver, allowing STA 200 to receive information or signal input and to transmit information to the processing system. Those skilled in the art will readily recognize that the first interface can also receive information or signal input, and the second interface can also output information or signal output.

[0050] User interface 230 (which is coupled to processor 220) may be or represent several suitable user input devices, such as, for example, a speaker, microphone, display device, keyboard, touch screen, etc. In some implementations, user interface 230 may allow a user to control several operations of STA 200, interact with one or more applications executable by STA 200, and perform other suitable functions.

[0051] In some implementations, STA 200 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 via an antenna (not shown for simplicity) from one or more satellites or satellite systems. The signals received by the SPS receiver 250 may be used to determine (or at least assist in determining) the position of STA 200.

[0052] Memory 240 may include device database 241, which may store location data, configuration information, data rate, media access control (MAC) address, timing information, modulation and decoding scheme (MCS), traffic indication (TID) queue size, ranging capability, and other appropriate information about (or relating to) STA 200. Device database 241 may also store profile information for several other wireless devices. Profile information for a given wireless device may include, for example, the wireless device's Service Set Identifier (SSID), Basic Service Set Identifier (BSSID), operating channel, TSF value, beacon spacing, ranging schedule, Channel Status Information (CSI), Received Signal Strength Indicator (RSSI) value, actual transmission amount value, and connection history with STA 200. In some implementations, profile information for a given wireless device may also include clock offset value, carrier frequency offset value, and ranging capability.

[0053] The memory 240 may also be or include a non-transitory computer-readable storage medium (such as one or more non-volatile memory elements, such as EPROM, EEPROM, flash memory, hard disk, etc.), which may store computer-executable instructions 242 to perform all or part of the one or more operations described in the present invention.

[0054] Figure 3 illustrates an exemplary access point (AP) 300. AP 300 may be an implementation of AP 110 of Figure 1. AP 300 may include one or more transceivers 310, a processor 320, memory 330, a network interface 340, and several antennas ANT1-ANTn. Transceivers 310 may be coupled directly to antennas ANT1-ANTn or via antenna selection circuitry (not shown for simplicity). Transceivers 310 may be used to transmit signals to and receive signals from one or more of the STAs 120a-120i of Figure 1 and other wireless devices and other APs. Although not shown in Figure 3 for simplicity, transceivers 310 may include any number of transmission chains to process signals and transmit signals via antennas ANT1-ANTn to other wireless devices, and may include any number of receive chains to process signals received from antennas ANT1-ANTn. Therefore, AP 300 may be configured for MIMO communication and OFDMA communication. MIMO communication can include SU-MIMO and MU-MIMO communication. In some implementations, the AP 300 can use multiple antennas ANT1-ANTn to provide antenna diversity. Antenna diversity can include polarization diversity, mode diversity, and spatial diversity.

[0055] In high-frequency (such as 60 GHz or millimeter-wave (mmWave)) wireless communication systems (such as IEEE 802.11a1 or 802.11ay revisions compliant with the IEEE 802.11 standard), beamforming can be performed on the communication using phased array antennas at both the transmitter and receiver. Beamforming generally refers to a wireless communication technique by which transmitting and receiving devices adjust the transmission or receiving antenna settings to achieve the desired link budget for subsequent communication. The procedure for adjusting the transmission and receiving antennas (referred to as beamforming training) can be initially performed to establish a link between the transmitting and receiving devices, and can also be performed periodically to maintain a quality link using optimized transmission and receiving beams.

[0056] Processor 320 may be any suitable one or more processors capable of executing scripts or instructions of one or more software programs stored in AP 300 (such as within memory 330). In some implementations, processor 320 may be or include one or more microprocessors providing processor functionality and external memory providing at least a portion of machine-readable medium. In other implementations, processor 320 may be or include an ASIC, wherein the processor, bus interface, user interface, and at least a portion of machine-readable medium are integrated into a single chip. In some other implementations, processor 320 may be or include one or more FPGAs or PLDs. In some implementations, processor 320 may be an element of a processing system. For example, the processing system of AP 300 may represent a system that includes various other elements or sub-elements of AP 300.

[0057] The processing system of AP 300 can interface with other components of AP 300 and can process information (such as inputs or signals) received from other components and output information to other components. For example, the chip or modem of AP 300 may include a processing system, a first interface for outputting information, and a second interface for receiving information. In some cases, the first interface may represent an interface between the processing system of the chip or modem and a transmitter, allowing AP 300 to transmit information output from the chip or modem. In some cases, the second interface may represent an interface between the processing system of the chip or modem and a receiver, allowing AP 300 to receive information or signal input and to transmit information to the processing system. Those skilled in the art will readily recognize that the first interface can also receive information or signal input, and the second interface can also output information or signal output.

[0058] The network interface 340 (which is coupled to the processor 320) can be used to communicate with the system controller 130 of FIG1. ​​The network interface 340 can also allow the AP 300 to communicate directly or via one or more intermediate networks with other wireless systems, other APs, one or more backhaul networks, or any combination thereof.

[0059] Memory 330 may include device database 331, which may store location data, configuration information, data rate, MAC address, timing information, MCS, ranging capability, and other appropriate information about (or relating to) AP 300. Device database 331 may also store profile information for several other wireless devices, such as one or more of stations 120a-120i in FIG. 1. Profile information for a given wireless device may include, for example, the wireless device's SSID, BSSID, operating channel, CSI, Received Signal Strength Indicator (RSSI) value, actual transmission volume value, and connection history with AP 300. In some implementations, profile information for a given wireless device may also include TID queue size, optimal 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.

[0060] Memory 330 may also be or include non-transitory computer-readable storage media (such as one or more non-volatile memory elements, such as EPROM, EEPROM, flash memory, hard disk, etc.), which may store computer-executable instructions 332 to perform all or part of the one or more operations described in the present invention.

[0061] Figure 4A illustrates a timing diagram 400 of an example of wireless communication between devices belonging to a BSS. In the example of Figure 4A, the BSS is shown as including a low-latency STA 402 and a non-traditional STA 404. The low-latency STA 402 is a member of a restricted TWT SP (r-TWT SP) that spans a duration from time t3 to t8, while the non-traditional STA 404 is not a member of the restricted TWT SP (and can therefore be referred to as a "non-member STA"). In some implementations, each of STAs 402 and 404 may be an instance of either STAs 120a-120i of Figure 1 or STA 200 of Figure 2. Although only one low-latency STA and one non-traditional STA are illustrated in the example of Figure 4A, in practical implementations, the BSS may include any number of low-latency STAs and any number of non-traditional STAs.

[0062] A non-traditional STA 404 attempts to access the shared wireless media before the start of a restricted TWT SP. More specifically, the non-traditional STA 404 senses that the media is idle for a threshold duration from time t0 to t1 based on channel sensing operations such as Idle Channel Assessment (CCA) and further counts down a random shift-behind (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 Inter-Frame Interval (AIFS) duration associated with a specific Access Class (AC) of data traffic. Thus, the RBO duration (from time t1 to t2) can be randomly selected from a series of RBOs spanning a contention window associated with the AC. At time t2, the non-traditional STA 404 senses that the wireless media is still idle and continues to acquire a TXOP, for example, by initiating a transmission on the shared media. However, existing rules regarding restricted TWT operations require non-member STAs to terminate their TXOPs until the start of the restricted TWT SP. Since the restricted TWT SP in Figure 4A starts at time t3, the non-traditional STA 404 must truncate its TXOP between time t2 and t3.

[0063] The low-latency STA 402 attempts to access the shared wireless media at the beginning of the restricted TWT SP. More specifically, the low-latency STA 402 senses that the media 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 of Figure 4A, the non-traditional STA 404 also attempts to access the shared wireless media at the beginning of the restricted TWT SP. For example, the non-traditional STA 404 senses that the media 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 STA 402 can be assigned to a higher priority AC than data traffic associated with the non-traditional STA 404. Therefore, the AIFS or RBO duration associated with the low-latency STA 402 can be shorter than the AIFS or RBO duration associated with the non-traditional STA 404, respectively. Therefore, the low-latency STA 402 wins access to the wireless media at time t6 and acquires TXOP, for example, by initiating a transmission on the shared media.

[0064] The non-traditional STA 404 senses wireless media busy at time t6 and avoids access to shared media for the duration of TXOP. After the TXOP has been terminated, at time t7, the non-traditional STA 404 can attempt to access the wireless media again. In this way, the restricted TWT operation may, for example, prioritize delay-sensitive messages in the BSS by requiring other non-traditional STAs to terminate their TXOP until the onset of the restricted TWT SP. In addition, APs (not illustrated for simplicity) can suppress messages from all conventional STAs associated with the BSS by scheduling quiet intervals to overlap with restricted TWT SPs. For example, the duration of the quiet interval may be indicated by one or more quiet elements included in management frames (such as beacon frames and probe response frames) transmitted by the AP prior to the onset of the restricted TWT SP.

[0065] FIG.4B illustrates the timing FIG.410 for instances of wireless communication between devices belonging to the BSS. In the example of Figure 4B , the BSS is shown to include a low-latency STA 412 and a non-traditional STA 414 . The low-latency STA 412 is a member of the restricted TWT SP (r-TWT SP) that spans the duration from time t2 to t6, whereas the non-traditional STA 414 is not a member of the restricted TWT SP (and can therefore be referred to as a “non-member STA”). In some embodiments, each of STA 412 and 414 may be an instance of any of STA 120a-120i of FIG. Despite the fact that only one low-latency STA and one non-traditional STA are plotted in the instance of Figure 4B , in a practical implementation, the BSS can include an arbitrary number of low-latency STAs and an arbitrary number of non-traditional STAs.

[0066] The non-traditional STA 414 attempts to access the shared wireless media before the start of the restricted TWT SP. More specifically, the non-traditional STA 414 senses that the media 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 the TXOP. In the example of Figure 4B, the RBO duration randomly selected by the non-traditional STA 414 is greater than the amount of time remaining before the start of the restricted TWT SP (from time t1 to t2). However, existing rules regarding restricted TWT operation do not prevent the RBO countdown from extending beyond the start of the restricted TWT SP. Therefore, at time t4, the non-traditional STA 414 senses that the wireless media is still idle and continues to acquire the TXOP, for example, by initiating a transmission on the shared wireless media. Thus, the non-traditional STA 414 gains access to the shared wireless media from time t4 to t5 during the restricted TWT SP. Since the non-traditional STA 414 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 operations.

[0067] The low-latency STA 412 attempts to access the shared wireless media at the beginning of the restricted TWT SP. More specifically, the low-latency STA 412 senses that the media is idle for the AIFS duration from time t2 to t3, and further counts down the RBO duration starting at time t3. In some implementations, the data traffic associated with the low-latency STA 412 can be assigned a higher priority AC than the data traffic associated with the non-traditional STA 414. Therefore, the AIFS or RBO duration associated with the low-latency STA 412 can be shorter than the AIFS or RBO duration associated with the non-traditional STA 414, respectively. However, since the non-traditional STA 414 starts its RBO countdown before the start of the restricted TWT SP, the non-traditional STA 414 is able to acquire the TXOP before the low-latency STA 412 completes its RBO countdown. Therefore, the low-latency STA 412 senses that the wireless media is busy at time t4 and avoids accessing the shared wireless media for the duration of the TXOP of the non-traditional STA 414. After the TXOP has ended, at time t5, the low-latency STA 412 can try to access the wireless media again.

[0068] Figure 4C illustrates a timing diagram 420 of an example of wireless communication between devices belonging to a BSS. In the example of Figure 4C, the BSS is shown as including a low-latency STA 422 and a non-traditional STA 424. The low-latency STA 422 is a member of a restricted TWT SP (r-TWT SP) that spans a duration from time t3 to t7, while the non-traditional STA 424 is not a member of a restricted TWT SP (and can therefore be referred to as a "non-member STA"). In some implementations, each of STAs 422 and 424 may be an instance of any of the STAs 120a-120i of Figure 1 or STA 200 of Figure 2. Although only one low-latency STA and one non-traditional STA are illustrated in the example of Figure 4C, in practical implementations, the BSS may include any number of low-latency STAs and any number of non-traditional STAs.

[0069] The non-traditional STA 424 attempts to access the shared wireless media before the start of the restricted TWT SP. More specifically, the non-traditional STA 424 senses that the media is idle for the AIFS duration from time t0 to t1, and further counts down the RBO duration from time t1 to t2 before attempting to acquire the TXOP. In the example of Figure 4C, the RBO countdown terminates before the start of the restricted TWT SP (at time t2). However, the non-traditional STA 424 may determine that the duration between the end of the RBO countdown and the start of the restricted TWT SP (from time t2 to t3) is not suitable for the (truncated) TXOP. Therefore, in some implementations, the non-traditional STA 424 may perform a new RBO countdown from time t2 to t5. At time t5, the non-traditional STA 424 senses that the wireless media is still idle, and continues to acquire the TXOP, for example, by initiating a transmission on the shared wireless media. Therefore, the non-traditional STA 424 gains access to the shared wireless media from time t5 to t6 during the restricted TWT SP. Since the non-traditional STA 424 does not acquire its TXOP before the start of the restricted TWT SP, the TXOP (from time t5 to t6) does not violate any existing rules regarding restricted TWT operation.

[0070] The low-latency STA 422 attempts to access the shared wireless media at the beginning of the restricted TWT SP. More specifically, the low-latency STA 422 senses that the media is idle for the AIFS duration from time t3 to t4, and further counts down the RBO duration starting at time t4. In some implementations, the data traffic associated with the low-latency STA 422 can be assigned a higher priority AC than the data traffic associated with the non-traditional STA 424. Therefore, the AIFS or RBO duration associated with the low-latency STA 422 can be shorter than the AIFS or RBO duration associated with the non-traditional STA 424, respectively. However, since the non-traditional STA 424 starts its second RBO countdown before the start of the restricted TWT SP, the non-traditional STA 424 is able to acquire the TXOP before the low-latency STA 422 completes its RBO countdown. Therefore, the low-latency STA 422 senses that the wireless media is busy at time t5 and avoids accessing the shared wireless media for the duration of the TXOP of the non-traditional STA 424. After the TXOP has ended, at time t6, the low-latency STA 422 can try to access the wireless media again.

[0071] Figures 4B and 4C illustrate that, under various conditions, a non-member STA can acquire a TXOP before a low-latency STA that is a member of the restricted TWT SP during the restricted TWT SP. Although the low-latency STA can access the radio media after the non-member STA's TXOP is completed, this delay in media access can significantly increase the latency of data traffic associated with the low-latency STA 412. Therefore, existing rules regarding restricted TWT operation may not provide sufficient protection for latency-sensitive traffic. Various aspects of the present invention can provide greater protection for latency-sensitive traffic by preventing non-member STAs from accessing the shared radio media for at least a threshold duration after the start of the restricted TWT SP. In some aspects, all non-member STAs can follow one or more rules that require such STAs to postpone access to the shared radio media at the start of each restricted TWT SP for at least a threshold duration. In some other configurations, the AP may transmit one or more frames that cause all non-member STAs to postpone access to the shared wireless media at the beginning of the restricted TWT SP for at least a threshold duration.

[0072] Figure 5 illustrates a timing diagram 500 of an example of wireless communication between devices belonging to a BSS. In the example of Figure 5, the BSS is shown as including low-latency STAs 502 and 504 and a non-traditional STA 506. Low-latency STAs 502 and 504 are members of a restricted TWT SP (r-TWT SP) that spans a duration from time t0 to t10, while non-traditional STA 506 is not a member of a restricted TWT SP. In some implementations, each of STAs 502-506 may be an instance of any of the STAs 120a-120i of Figure 1 or STA 200 of Figure 2. Although only two low-latency STAs and one non-traditional STA are illustrated in the example of Figure 5, in practical implementations, the BSS may include any number of low-latency STAs and any number of non-traditional STAs.

[0073] The first low-latency STA 502 attempts to access the shared wireless media at the beginning of the restricted TWT SP. More specifically, the first low-latency STA 502 senses that the media 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 the TXOP. In the example of Figure 5, the second low-latency STA 504 also attempts to access the shared wireless media at the beginning of the restricted TWT SP.

[0074] In some implementations, to reduce the possibility of conflicts between low-latency STAs 502 and 504, the second low-latency STA 504 may wait for a contention offset duration from time t0 to t1 before contending for media access. Therefore, the first low-latency STA 502 wins access to the wireless media and acquires the TXOP from time t4 to t5. During the TXOP, the first low-latency STA 502 may transmit or receive latency-sensitive traffic to or from the AP or another STA (such as in peer-to-peer communication). The second low-latency STA 504 senses that the media is idle during the AIFS duration from time t1 to t3 and further counts down the RBO duration starting at time t3. However, the second low-latency STA 504 senses that the wireless media is busy at time t4 and avoids accessing the shared media during the duration of the TXOP.

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

[0076] Non-traditional STA 506 senses that the media is idle during the AIFS duration from time t0 to t3, and further counts down the RBO duration starting at time t3. In some implementations, data traffic associated with non-traditional STA 506 can be assigned to a lower priority AC than data traffic associated with low-latency STAs 502 and 504. Therefore, non-traditional STA 506 loses media access to the first low-latency STA 502. Non-traditional STA 506 senses that the wireless media is busy at time t4 and avoids accessing the shared media during the TXOP duration.

[0077] After the TXOP of the first low-latency STA 502 has ended, at time t5, the second low-latency STA 504 and the non-traditional STA 506 can again contend for access to the wireless media. As shown in Figure 5, the second low-latency STA 504 senses that the media 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-traditional STA 506 senses that the media is idle during the AIFS duration from time t5 to t7, and further counts down the RBO duration starting at time t7.

[0078] In some implementations, data traffic associated with the second low-latency STA 504 can be assigned a higher priority AC than data traffic associated with the non-traditional STA 506. Therefore, the second low-latency STA 504 wins access to the wireless media and acquires the TXOP from time t8 to t9. The non-traditional STA 506 senses wireless media busy at time t8 and avoids accessing the shared media during the duration of the TXOP. After the TXOP of the second low-latency STA 504 has ended, at time t9, the non-traditional STA 506 can again contend for access to the wireless media.

[0079] In some implementations, membership in a restricted TWT SP may be restricted so that each low-latency STA associated with the SP has a greater probability of obtaining a TXOP within a relatively short time frame. Referring, for example, to Figure 5, if membership in a restricted TWT SP is restricted to 2, any additional low-latency STA in the BSS can be assigned to a different restricted TWT SP.

[0080] In the example of Figure 5, it is assumed that data traffic associated with non-traditional STA 506 is assigned to a lower priority AC than data traffic associated with low-latency STAs 502 and 504. However, in some cases, data traffic associated with each of STAs 502-506 can be assigned to the same AC. In this case, the likelihood of either low-latency STA 502 or 504 winning access to the radio media relative to non-traditional STA 506 is significantly reduced. In some implementations, to further protect latency-sensitive traffic in a restricted TWT SP, non-member STAs may be prohibited from accessing the radio media during the restricted TWT SP.

[0081] Figure 6 illustrates a timing diagram 600 of an example of wireless communication between devices belonging to a BSS. In the example of Figure 6, the BSS is shown as including low-latency STAs 602 and 604 and a non-traditional STA 606. Low-latency STAs 602 and 604 are members of a restricted TWT SP (r-TWT SP) that spans a duration from time t0 to t8, while non-traditional STA 606 is not a member of a restricted TWT SP. In some implementations, each of STAs 602-606 may be an instance of any of the STAs 120a-120i of Figure 1 or STA 200 of Figure 2. Although only two low-latency STAs and one non-traditional STA are illustrated in the example of Figure 6, in practical implementations, the BSS may include any number of low-latency STAs and any number of non-traditional STAs.

[0082] The first low-latency STA 602 attempts to access the shared wireless media at the beginning of the restricted TWT SP. More specifically, the first low-latency STA 602 senses that the media 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 the TXOP. In the example of Figure 6, the second low-latency STA 604 also attempts to access the shared wireless media at the beginning of the restricted TWT SP.

[0083] In some implementations, to reduce the possibility of conflicts between low-latency STAs 602 and 604, the second low-latency STA 604 may wait for a contention offset duration from time t0 to t1 before contending for media access. Therefore, the first low-latency STA 602 wins access to the wireless media and acquires the TXOP from time t4 to t5. During the TXOP, the first low-latency STA 602 may transmit or receive latency-sensitive traffic to or from the AP or another STA (such as in peer-to-peer communication). The second low-latency STA 604 senses that the media is idle during the AIFS duration from time t1 to t3 and further counts down the RBO duration starting at time t3. However, the second low-latency STA 604 senses that the wireless media is busy at time t4 and avoids accessing the shared media during the duration of the TXOP.

[0084] In some implementations, all non-traditional STAs may be required to defer access to the shared wireless media for the duration of each restricted TWT SP. In other words, any non-member STA with data to transmit or receive during the restricted TWT SP must wait before contending for media access until the restricted TWT SP has terminated. Non-traditional STA 606 may attempt to access the wireless media before the start of the restricted TWT SP (as described with reference to Figures 4A-4C). However, whether non-traditional STA 606 acquires the truncated TXOP or continues the countdown RBO, non-traditional STA 606 must defer media access for the duration of the restricted TWT SP from time t0 to t8.

[0085] After the TXOP of the first low-latency STA 602 has terminated, at time t5, the second low-latency STA 604 can again contend for access to the wireless media. As shown in Figure 6, the second low-latency STA 604 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 acquires the TXOP from time t7 to t8. After the restricted TWT SP has terminated, at time t8, the non-traditional STA 606 can again contend for access to the wireless media. As shown in Figure 6, the non-traditional STA 606 senses that the media is idle during the AIFS duration from time t8 to t9, and further counts down the RBO duration starting from time t9.

[0086] In some implementations, membership in a restricted TWT SP may be restricted so that each low-latency STA associated with the SP has a greater probability of obtaining a TXOP within a relatively short time frame. Referring, for example, to Figure 6, if membership in a restricted TWT SP is restricted to 2, any additional low-latency STA in the BSS can be assigned to a different restricted TWT SP.

[0087] It is understood that, in some cases, a low-latency STA assigned to a limited TWT SP may not utilize all (or any) SPs to transmit or receive time-sensitive traffic. In such cases, requiring a non-member STA to defer media access for the duration of the limited TWT SP may result in underutilization of the shared radio media. In some implementations, to improve media utilization during the limited TWT SP, it may be necessary to require a non-member STA to defer media access for only a portion of the limited TWT SP.

[0088] Figure 7 illustrates a timing diagram 700 of an example of wireless communication between devices belonging to a BSS. In the example of Figure 7, the BSS is shown as including low-latency STAs 702 and 704 and a non-traditional STA 706. Low-latency STAs 702 and 704 are members of a restricted TWT SP (r-TWT SP) that spans a duration from time t0 to t11, while non-traditional STA 706 is not a member of a restricted TWT SP. In some implementations, each of STAs 702-706 may be an instance of any of the STAs 120a-120i of Figure 1 or STA 200 of Figure 2. Although only two low-latency STAs and one non-traditional STA are illustrated in the example of Figure 7, in practical implementations, the BSS may include any number of low-latency STAs and any number of non-traditional STAs.

[0089] The first low-latency STA 702 attempts to access the shared wireless media at the beginning of the restricted TWT SP. More specifically, the first low-latency STA 702 senses that the media 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 the TXOP. In the example of Figure 7, the second low-latency STA 704 also attempts to access the shared wireless media at the beginning of the restricted TWT SP.

[0090] In some implementations, to reduce the possibility of conflicts between low-latency STAs 702 and 704, the second low-latency STA 704 may wait for a contention offset duration from time t0 to t1 before contending for media access. Therefore, the first low-latency STA 702 wins access to the wireless media and acquires the TXOP from time t4 to t6. During the TXOP, the first low-latency STA 702 may transmit or receive latency-sensitive traffic to or from the AP or another STA (such as in peer-to-peer communication). The second low-latency STA 704 senses that the media is idle during the AIFS duration from time t1 to t3 and further counts down the RBO duration starting at time t3. However, the second low-latency STA 704 senses that the wireless media is busy at time t4 and avoids accessing the shared media during the duration of the TXOP.

[0091] In some implementations, all non-traditional STAs may be required to postpone access to the shared wireless media for a quiet duration from the beginning of each restricted TWT SP. In other words, any non-member STA with data to transmit or receive during the restricted TWT SP must wait until the quiet duration has expired before it can contend for media access. In some implementations, the quiet duration can be signaled by the AP (not illustrated for simplicity). For example, the quiet duration can be indicated by a quiet element carried in a management frame (such as a beacon or probe response) transmitted by the AP. Non-traditional STA 706 may attempt to access the wireless media before the start of the restricted TWT SP (as described with reference to Figures 4A-4C). However, whether the non-traditional STA 706 acquires a truncated TXOP or continues the countdown RBO, the non-traditional STA 706 must postpone media access for at least a quiet duration from time t0 to t5.

[0092] Non-traditional STA 706 senses that the wireless media is busy during the remainder of the TXOP (from time t5 to t6). After the TXOP of the first low-latency STA 702 has ended, at time t6, the second low-latency STA 704 and non-traditional STA 706 can again contend for access to the wireless media. As shown in Figure 7, the second low-latency STA 704 senses that the media 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. Non-traditional STA 706 senses that the media is idle during the AIFS duration from time t6 to t8, and further counts down the RBO duration starting at time t8.

[0093] In some implementations, data traffic associated with the second low-latency STA 704 can be assigned a higher priority AC than data traffic associated with the non-traditional STA 706. Therefore, the second low-latency STA 704 wins access to the wireless media and acquires the TXOP from time t9 to t10. The non-traditional STA 706 senses wireless media busy at time t9 and avoids accessing the shared media during the duration of the TXOP. After the TXOP of the second low-latency STA 704 has ended, at time t10, the non-traditional STA 706 can again contend for access to the wireless media.

[0094] In some implementations, membership in a restricted TWT SP may be restricted so that each low-latency STA associated with the SP has a greater probability of obtaining a TXOP within a relatively short time frame. Referring, for example, to Figure 7, if membership in a restricted TWT SP is restricted to 2, any additional low-latency STA in the BSS can be assigned to a different restricted TWT SP.

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

[0096] The implementation described with reference to Figures 5-7 relies on non-member STAs following updated rules regarding restricted TWT operation. For example, such updates to the rules can be implemented via future revisions to the IEEE 802.11 standard. However, it is recognized that non-traditional STAs conforming to existing versions of the IEEE 802.11 standard may not follow the updated rules. Therefore, in some other implementations, existing wireless communication protocols can be used to explicitly signal non-member STAs to postpone media access. In this implementation, the AP can capture the wireless media at the beginning of the TWT SP and transmit one or more packets that cause non-member STAs to postpone media access for at least a threshold interval, while allowing low-latency STAs to access the wireless media during this interval.

[0097] Figure 8A illustrates a timing diagram 800 of an example of wireless communication between devices belonging to a BSS. In the example of Figure 8A, the BSS is illustrated as including AP 802, low-latency STA 804, and non-traditional STA 806. Low-latency STA 804 is a member of a restricted TWT SP (r-TWT SP) that spans a duration from time t1 to t9, while non-traditional STA 806 is not a member of a restricted TWT SP. In some implementations, AP 802 may be an instance of AP 110 of Figure 1 or AP 300 of Figure 3. In some implementations, each of STAs 804 and 806 may be an instance of any of STAs 120a-120i of Figure 1 or STA 200 of Figure 2. Although only one low-latency STA and one non-traditional STA are illustrated in the example of Figure 8A, in practical implementations, the BSS may include any number of low-latency STAs and any number of non-traditional STAs.

[0098] In some implementations, AP 802 may transmit a Clear Transmission (CTS) to its own frame on the shared radio media at the beginning of the restricted TWT SP. More specifically, AP 802 attempts to time the transmission of the CTS to its own frame to coincide with the beginning of the restricted TWT SP. In the example of Figure 8A, the non-traditional STA 806 is counting down its RBO duration before the beginning of the restricted TWT SP. AP 802 senses that the media is idle during the Point Coordination Function (PCF) Inter-Frame Space (PIFS) duration from time t0 to t1 and continues transmitting the CTS to its own frame at time t1. Low-latency STA 804 also attempts to access the shared radio media at the beginning of the restricted TWT SP. However, low-latency STA 804 senses that the media is busy from time t1 to t2 during the transmission of the CTS to its own frame.

[0099] In some implementations, the duration field of CTS to its own frame (in the MAC header) can be used to protect time-sensitive traffic in a restricted TWT SP. More specifically, the value of the duration field indicates the duration within which the wireless media is reserved. Existing versions of STAs compliant with the IEEE 802.11 standard must defer media access for at least the duration indicated by the duration field. In some implementations, to protect time-sensitive traffic in a restricted TWT SP, the duration indicated by the duration field may be greater than the duration required to transmit the trigger frame. As shown in Figure 8A, a non-traditional STA 806 sets its Network Assignment Vector (NAV) to the duration indicated by the duration field of CTS to its own frame, which spans from time t2 to t5.

[0100] In some implementations, the low-latency STA can be configured to ignore any CTS-to-self frames transmitted by the AP at the beginning of the restricted TWT SP. Therefore, the low-latency STA 804 does not set its NAV based on the CTS-to-self frame duration field. Alternatively, the low-latency STA 804 can begin contention for media access immediately after the CTS-to-self frame transmission. As shown in Figure 8A, the low-latency STA 804 senses that the media is idle during the AIFS duration from time t2 to t3, counts down the RBO duration from time t3 to t4, and acquires the TXOP from time t4 to t6. During the TXOP, the low-latency STA 804 can transmit or receive latency-sensitive traffic to or from the AP or another STA (such as in peer-to-peer communication).

[0101] At the end of the NAV duration, at time t5, the non-traditional STA 806 can contend for media access. However, due to the TXOP of the low-latency STA 804, the non-traditional STA 806 senses media busy at time t5. Therefore, the non-traditional STA 806 avoids accessing the shared media during the duration of the TXOP. After the TXOP of the low-latency STA 804 has ended, at time t6, the non-traditional STA 806 can contend for media access again. As shown in Figure 8A, the non-traditional STA 806 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 acquires the TXOP from time t8 to t9.

[0102] In some implementations, multiple low-latency STAs may be members of a restricted TWT SP. In such implementations, non-traditional STAs 806 may postpone their media access for even longer periods (as described with reference to Figures 5-7). For example, since data traffic associated with a low-latency STA can be assigned a higher priority AC than data traffic associated with a non-member STA, a low-latency STA is more likely to win media access relative to a non-member STA during a given contention period.

[0103] In some implementations, membership in a restricted TWT SP may be restricted so that each low-latency STA associated with the SP has a greater probability of obtaining a TXOP within a relatively short time frame. Referring, for example, to Figure 8A, if membership in a restricted TWT SP is restricted to 2, any additional low-latency STA in the BSS can be assigned to a different restricted TWT SP.

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

[0105] Figure 8B illustrates a timing diagram 810 of an example of wireless communication between devices belonging to a BSS. In the example of Figure 8B, the BSS is illustrated as including AP 812, low-latency STA 814, and non-traditional STA 816. Low-latency STA 814 is a member of a restricted TWT SP (r-TWT SP) that spans a duration from time t0 to t9, while non-traditional STA 816 is not a member of a restricted TWT SP. In some implementations, AP 812 may be an instance of AP 110 of Figure 1 or AP 300 of Figure 3. In some implementations, each of STAs 814 and 816 may be an instance of any of STAs 120a-120i of Figure 1 or STA 200 of Figure 2. Although only one low-latency STA and one non-traditional STA are illustrated in the example of Figure 8B, in practical implementations, the BSS may include any number of low-latency STAs and any number of non-traditional STAs.

[0106] In some implementations, AP 812 may transmit CTS to its own frame on the shared wireless media at the beginning of the restricted TWT SP. More specifically, AP 812 attempts to time the transmission of CTS to its own frame to coincide with the beginning of the restricted TWT SP. In the example of Figure 8B, the non-traditional STA 816 acquires the truncated TXOP before the beginning of the restricted TWT SP. AP 812 senses that the media is idle during the PIFS duration from time t0 to t1 and continues transmitting CTS to its own frame at time t1. Low-latency STA 814 also attempts to access the shared wireless media at the beginning of the restricted TWT SP. However, since the PIFS duration is shorter than any AIFS duration, AP 812 wins media access relative to low-latency STA 814. Therefore, low-latency STA 814 senses that the media is busy from time t1 to t2 during the transmission of CTS to its own frame.

[0107] In some implementations, the duration field of the CTS to its own frame (in the MAC header) can be used to protect time-sensitive traffic in a restricted TWT SP. As described with reference to FIG8A, existing versions of STAs conforming to the IEEE 802.11 standard must postpone media access for at least the duration indicated by the duration field. In some implementations, to protect time-sensitive traffic in a restricted TWT SP, the duration indicated by the duration field may be greater than the duration required to transmit the trigger frame. As shown in FIG8B, a non-traditional STA 816 sets its NAV to the duration indicated by the duration field of the CTS to its own frame, which spans the duration from time t2 to t5.

[0108] In some implementations, the low-latency STA can be configured to ignore any CTS-to-self frames transmitted by the AP at the beginning of the restricted TWT SP. Therefore, the low-latency STA 814 does not set its NAV based on the CTS-to-self frame duration field. Alternatively, the low-latency STA 814 can begin contention for the wireless media immediately after the CTS-to-self frame transmission. As shown in Figure 8B, the low-latency STA 814 senses that the media is idle during the AIFS duration from time t2 to t3, counts down the RBO duration from time t3 to t4, and acquires the TXOP from time t4 to t6. During the TXOP, the low-latency STA 814 can transmit or receive latency-sensitive traffic to or from the AP or another STA (such as in peer-to-peer communication).

[0109] At the end of the NAV duration, at time t5, the non-traditional STA 816 can contend for media access. However, due to the TXOP of the low-latency STA 814, the non-traditional STA 816 senses media busy at time t5. Therefore, the non-traditional STA 816 avoids accessing the shared media during the duration of the TXOP. After the TXOP of the low-latency STA 814 has ended, at time t6, the non-traditional STA 816 can contend for media access again. As shown in Figure 8B, the non-traditional STA 816 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 acquires the TXOP from time t8 to t9.

[0110] In some implementations, multiple low-latency STAs (not illustrated for simplicity) may be members of a restricted TWT SP. In this implementation, non-traditional STAs 816 may postpone their media access for even longer periods (e.g., as described with reference to Figures 5-7). For example, since data traffic associated with a low-latency STA can be assigned to a higher priority AC than data traffic associated with a non-member STA, a low-latency STA is more likely to win media access relative to a non-member STA during a given contention period.

[0111] In some implementations, membership in a restricted TWT SP may be restricted so that each low-latency STA associated with the SP has a greater probability of obtaining a TXOP within a relatively short amount of time. Referring, for example, to Figure 8B, if membership in a restricted TWT SP is restricted to 2, any additional low-latency STA in the BSS can be assigned to a different restricted TWT SP.

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

[0113] Figure 9A illustrates a timing diagram 900 of an example of wireless communication between devices belonging to a BSS. In the example of Figure 9A, the BSS is illustrated as including AP 902, low-latency STA 904, and non-traditional STA 906. Low-latency STA 904 is a member of a restricted TWT SP (r-TWT SP) that spans a duration from time t1 to t8, while non-traditional STA 906 is not a member of a restricted TWT SP. In some implementations, AP 902 may be an instance of AP 110 of Figure 1 or AP 300 of Figure 3. In some implementations, each of STAs 904 and 906 may be an instance of any of STAs 120a-120i of Figure 1 or STA 200 of Figure 2. Although only one low-latency STA and one non-traditional STA are illustrated in the example of Figure 9A, in practical implementations, the BSS may include any number of low-latency STAs and any number of non-traditional STAs.

[0114] In some implementations, AP 902 may transmit a trigger frame on the shared wireless media at the start of the restricted TWT SP. More specifically, AP 902 attempts to time the transmission of the trigger frame to coincide with the start of the restricted TWT SP. In the example of Figure 9A, the non-traditional STA 906 is counting down its RBO duration before the start of the restricted TWT SP. AP 902 senses that the media is idle during the PIFS duration from time t0 to t1 and continues transmitting the trigger frame at time t1. In some implementations, the trigger frame may request a trigger-based (TB) Entity Layer Convergence Protocol (PLCP) Protocol Data Unit (PPDU) from one or more low-latency STAs, such as low-latency STA 904. As shown in Figure 9A, low-latency STA 904 responds to the trigger frame at time t3 by transmitting uplink (UL) data to AP 902 in a TB PPDU.

[0115] In some implementations, the duration field of the trigger frame (in the MAC header) can be used to protect time-delay-sensitive traffic in a restricted TWT SP. As described with reference to FIG8A, existing versions of STAs conforming to 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 longer than the duration required to transmit the trigger frame. As shown in FIG9A, a non-traditional STA 906 sets its NAV to the duration indicated by the duration field of the trigger frame, which spans the duration from time t2 to t4.

[0116] At the end of the NAV duration, at time t4, the non-traditional STA 906 can contend for media access. However, the non-traditional STA 906 senses that the media is busy at time t4 due to the transmission of the TB PPDU. Therefore, the non-traditional STA 906 avoids accessing the shared media during the duration of the TB PPDU. After the transmission of the TB PPDU has been completed, at time t5, the non-traditional STA 906 can contend for media access again. As shown in Figure 9A, the non-traditional STA 906 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 acquires the TXOP from time t7 to t8.

[0117] In some implementations, a trigger frame can be used to request TB PPDUs from multiple low-latency STAs (not shown for simplicity). In this implementation, multiple low-latency STAs can concurrently transmit corresponding UL data (from time t3 to t5) to AP 902 in a TB PPDU. In some implementations, AP 902 can poll the low-latency STAs before the start of the restricted TWT SP to determine which STA (if any) has the UL data to transmit. For example, AP 902 can transmit a Buffer Status Report Polling (BSRP) trigger frame to the low-latency STAs associated with the restricted TWT SP. Each low-latency STA responds to the BSRP trigger frame by transmitting a Buffer Status Report (BSR) indicating the amount of UL data buffered by the STA back to AP 902. AP 902 can use the information carried in each BSR to determine the resource allocation for the TB PPDU.

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

[0119] Figure 9B illustrates a timing diagram 910 of an example of wireless communication between devices belonging to a BSS. In the example of Figure 9B, the BSS is illustrated as including AP 912, low-latency STA 914, and non-traditional STA 916. Low-latency STA 914 is a member of a restricted TWT SP (r-TWT SP) that spans a duration from time t0 to t8, while non-traditional STA 916 is not a member of a restricted TWT SP. In some implementations, AP 912 may be an instance of AP 110 of Figure 1 or AP 300 of Figure 3. In some implementations, each of STAs 914 and 916 may be an instance of any of STAs 120a-120i of Figure 1 or STA 200 of Figure 2. Although only one low-latency STA and one non-traditional STA are illustrated in the example of Figure 9B, in practical implementations, the BSS may include any number of low-latency STAs and any number of non-traditional STAs.

[0120] In some implementations, AP 912 may transmit a trigger frame on the shared wireless media at the start of the restricted TWT SP. More specifically, AP 912 attempts to time the transmission of the trigger frame to coincide with the start of the restricted TWT SP. In the example of Figure 9B, a non-traditional STA 916 acquires a truncated TXOP before the start of the restricted TWT SP. AP 912 senses that the media is idle for the duration of PIFS from time t0 to t1 and continues transmitting the trigger frame at time t1. The trigger frame request comes from one or more low-latency STAs (such as low-latency STA 914) via a TB PPDU. As shown in Figure 9B, low-latency STA 914 responds to the trigger frame at time t3 by transmitting uplink (UL) data to AP 912 in a TB PPDU.

[0121] In some implementations, the duration field of the trigger frame (in the MAC header) can be used to protect time-sensitive traffic in a restricted TWT SP. As described with reference to FIG8A, existing versions of STAs conforming to the IEEE 802.11 standard must postpone media access for at least the duration indicated by the duration field. Therefore, to protect time-sensitive traffic, the duration indicated by the duration field may be longer than the duration required to transmit the trigger frame. As shown in FIG9B, a non-traditional STA 916 sets its NAV to the duration indicated by the duration field of the trigger frame, which spans the duration from time t2 to t4.

[0122] At the end of the NAV duration, at time t4, the non-traditional STA 916 can contend for media access. However, the non-traditional STA 916 senses that the media is busy at time t4 due to the transmission of the TB PPDU. Therefore, the non-traditional STA 916 avoids accessing the shared media during the duration of the TB PPDU. After the transmission of the TB PPDU is completed, at time t5, the non-traditional STA 916 can contend for media access again. As shown in Figure 9B, the non-traditional STA 916 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 acquires the TXOP from time t7 to t8.

[0123] In some implementations, a trigger frame can be used to request TB PPDUs from multiple low-latency STAs (not shown for simplicity). In this implementation, multiple low-latency STAs can concurrently transmit corresponding UL data (from time t3 to t5) to AP 912 in the TB PPDU. In some implementations, AP 912 can poll the low-latency STAs before the start of the restricted TWT SP to determine which STA (if any) has the UL data to transmit. For example, AP 912 can transmit a BSRP trigger frame to the low-latency STA associated with the restricted TWT SP. Each low-latency STA responds to the BSRP trigger frame by transmitting a BSR indicating the amount of UL data buffered by the STA back to AP 912. AP 912 can use the information carried in each BSR to determine the resource allocation for the TB PPDU.

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

[0125] Figure 10A illustrates a timing diagram 1000 of an example of wireless communication between devices belonging to a BSS. In the example of Figure 10A, the BSS is illustrated as including AP 1002, low-latency STA 1004, and non-traditional STA 1006. Low-latency STA 1004 is a member of a restricted TWT SP (r-TWT SP) that spans a duration from time t1 to t11, while non-traditional STA 1006 is not a member of a restricted TWT SP. In some implementations, AP 1002 may be an instance of AP 110 of Figure 1 or AP 300 of Figure 3. In some implementations, each of STAs 1004 and 1006 may be an instance of any of STAs 120a-120i of Figure 1 or STA 200 of Figure 2. Although only one low-latency STA and one non-traditional STA are illustrated in the example of Figure 10A, in actual implementations, the BSS can include any number of low-latency STAs and any number of non-traditional STAs.

[0126] In some implementations, AP 1002 may transmit a Multi-User (MU) Request Transmission (RTS) frame on the shared radio medium at the beginning of the restricted TWT SP. More specifically, AP 1002 attempts to time the transmission of the MU-RTS frame to coincide with the beginning of the restricted TWT SP. In the example of Figure 10A, the non-traditional STA 1006 is counting down its RBO duration before the beginning of the restricted TWT SP. Therefore, AP 1002 senses that the medium is idle during the PIFS duration from time t0 to t1 and continues transmitting 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 STA 1004). As shown in Figure 10A, low-latency STA 1004 responds to the MU-RTS at time t3 by transmitting a CTS back to AP 1002.

[0127] In some implementations, the duration field of the MU-RTS frame (in the MAC header) can be used to protect time-delay-sensitive traffic in a restricted TWT SP. As described with reference to FIG8A, existing versions of STAs conforming to 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 longer than the duration required to transmit the MU-RTS frame. As shown in FIG10A, a non-traditional STA 1006 sets its NAV to the duration indicated by the duration field of the MU-RTS frame, which spans the duration from time t2 to t7. In some other implementations, a non-traditional STA 1006 sets its NAV to the duration indicated by the duration field of the CTS frame.

[0128] In some implementations, the low-latency STA can be configured to ignore the duration field of the MU-RTS frame transmitted by the AP at the beginning of the restricted TWT SP. Therefore, the low-latency STA 1004 does not set its NAV based on the duration field of the MU-RTS frame. Alternatively, the low-latency STA 1004 can begin contention 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 acquires the TXOP from time t6 to t8. During the TXOP, the low-latency STA 1004 can transmit or receive latency-sensitive traffic to or from the AP or another STA (such as in peer-to-peer communication).

[0129] At the end of the NAV duration, at time t7, the non-traditional STA 1006 can contend for media access. However, due to the TXOP of the low-latency STA 1004, the non-traditional STA 1006 senses media busy at time t7. Therefore, the non-traditional STA 1006 avoids accessing the shared media during the duration of the TXOP. After the TXOP of the low-latency STA 1004 has ended, at time t8, the non-traditional STA 1006 can contend for media access again. As shown in Figure 10A, the non-traditional STA 1006 senses that the media is idle during the AIFS duration from time t8 to t9, counts down the RBO duration from time t9 to t10, and acquires the TXOP from time t10 to t11.

[0130] In some implementations, the MU-RTS can identify multiple low-latency STAs (not illustrated for simplicity). In this implementation, each low-latency STA can respond to the MU-RTS frame by transmitting the corresponding CTS frame from time t3 to t4. Therefore, non-traditional STAs 1006 can postpone their media access for even longer periods (as described with reference to Figures 5-7). For example, since data traffic associated with a low-latency STA can be assigned to a higher priority AC than data traffic associated with a non-member STA, a low-latency STA is more likely to win media access relative to a non-member STA during a given contention period.

[0131] In some implementations, membership in a restricted TWT SP may be restricted so that each low-latency STA associated with the SP has a greater probability of obtaining a TXOP within a relatively short amount of time. Referring, for example, to Figure 10A, if membership in a restricted TWT SP is restricted to 2, any additional low-latency STA in the BSS can be assigned to a different restricted TWT SP.

[0132] In some implementations, the NAV duration indicated by the duration field from the CTS to its own frame can be selected to balance the efficiency of media utilization with the latency gain of latency-sensitive traffic. In the example of Figure 10A, the NAV duration is configured to terminate before the end of a single TXOP. However, in some other implementations, the NAV duration can be configured to span one or more TXOPs.

[0133] Figure 10B illustrates a timing diagram 1010 of an example of wireless communication between devices belonging to a BSS. In the example of Figure 10B, the BSS is illustrated as including AP 1012, low-latency STA 1014, and non-traditional STA 1016. Low-latency STA 1014 is a member of a restricted TWT SP (r-TWT SP) that spans a duration from time t0 to t11, while non-traditional STA 1016 is not a member of a restricted TWT SP. In some implementations, AP 1012 may be an instance of AP 110 of Figure 1 or AP 300 of Figure 3. In some implementations, each of STAs 1014 and 1016 may be an instance of any of STAs 120a-120i of Figure 1 or STA 200 of Figure 2. Although only one low-latency STA and one non-traditional STA are illustrated in the example of Figure 10B, in actual implementations, the BSS can include any number of low-latency STAs and any number of non-traditional STAs.

[0134] In some implementations, AP 1012 may transmit MU-RTS frames over the shared wireless medium at the start of the restricted TWT SP. More specifically, AP 1012 attempts to time the transmission of the MU-RTS frames to coincide with the start of the restricted TWT SP. In the example of Figure 10B, non-traditional STA 1016 acquires a truncated TXOP before the start of the restricted TWT SP. AP 1012 senses that the medium is idle during the PIFS duration from time t0 to t1 and continues transmitting MU-RTS frames at time t1. In some implementations, the MU-RTS frames may identify one or more low-latency STAs (such as low-latency STA 1014). As shown in Figure 10B, low-latency STA 1014 responds to the MU-RTS at time t3 by transmitting a CTS back to AP 1012.

[0135] In some implementations, the duration field of the MU-RTS frame (in the MAC header) can be used to protect time-delay-sensitive traffic in a restricted TWT SP. As described with reference to FIG8A, existing versions of STAs conforming to 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 longer than the duration required to transmit the MU-RTS frame. As shown in FIG10B, the non-traditional STA 1016 sets its NAV to the duration indicated by the duration field of the MU-RTS frame, which spans the duration from time t2 to t7. In some other implementations, the non-traditional STA 1016 sets its NAV to the duration indicated by the duration field of the CTS frame.

[0136] In some implementations, the low-latency STA can be configured to ignore the duration field of the MU-RTS frame transmitted by the AP at the beginning of the restricted TWT SP. Therefore, the low-latency STA 1014 does not set its NAV based on the duration field of the MU-RTS frame. Alternatively, the low-latency STA 1014 can begin contention for media access immediately after the CTS transmission. 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 acquires the TXOP from time t6 to t8. During the TXOP, the low-latency STA 1014 can transmit or receive latency-sensitive traffic to or from the AP or another STA (such as in peer-to-peer communication).

[0137] At the end of the NAV duration, at time t7, the non-traditional STA 1016 can contend for media access. However, due to the TXOP of the low-latency STA 1014, the non-traditional STA 1016 senses media busy at time t7. Therefore, the non-traditional STA 1016 avoids accessing the shared media during the duration of the TXOP. After the TXOP of the low-latency STA 1014 has ended, at time t8, the non-traditional STA 1016 can contend for media access again. As shown in Figure 10B, the non-traditional STA 1016 senses that the media is idle during the AIFS duration from time t8 to t9, counts down the RBO duration from time t9 to t10, and acquires the TXOP from time t10 to t11.

[0138] In some implementations, the MU-RTS can identify multiple low-latency STAs (not illustrated for simplicity). In this implementation, each low-latency STA can respond to the MU-RTS frame by transmitting the corresponding CTS frame from time t3 to t4. Therefore, non-traditional STAs 1016 can postpone their media access for even longer periods (as described with reference to Figures 5-7). For example, since data traffic associated with a low-latency STA can be assigned to a higher priority AC than data traffic associated with a non-member STA, a low-latency STA is more likely to win media access relative to a non-member STA during a given contention period.

[0139] In some implementations, membership in a restricted TWT SP may be restricted so that each low-latency STA associated with the SP has a greater probability of obtaining a TXOP within a relatively short amount of time. Referring, for example, to Figure 10B, if membership in a restricted TWT SP is restricted to 2, any additional low-latency STA in the BSS can be assigned to a different restricted TWT SP.

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

[0141] Figure 11A illustrates a timing diagram 1100 of an example of wireless communication between devices belonging to a BSS. In the example of Figure 11A, the BSS is illustrated as including AP 1102, low-latency STA 1104, and non-traditional STA 1106. Low-latency STA 1104 is a member of a restricted TWT SP (r-TWT SP) that spans a duration from time t1 to t12, while non-traditional STA 1106 is not a member of a restricted TWT SP. In some implementations, AP 1102 may be an instance of AP 110 of Figure 1 or AP 300 of Figure 3. In some implementations, each of STAs 1104 and 1106 may be an instance of any of STAs 120a-120i of Figure 1 or STA 200 of Figure 2. Although only one low-latency STA and one non-traditional STA are illustrated in the example of Figure 11A, in actual implementations, the BSS can include any number of low-latency STAs and any number of non-traditional STAs.

[0142] In some implementations, AP 1102 may transmit MU-RTS frames over the shared wireless medium at the start of the restricted TWT SP. More specifically, AP 1102 attempts to time the transmission of the MU-RTS frames to coincide with the start of the restricted TWT SP. In the example of Figure 11A, the non-traditional STA 1106 is counting down its RBO duration before the start of the restricted TWT SP. Therefore, AP 1102 senses that the medium is idle during the PIFS duration from time t0 to t1 and continues transmitting MU-RTS frames at time t1. In some implementations, the MU-RTS frames may identify one or more low-latency STAs (such as low-latency STA 1104). As shown in Figure 11A, low-latency STA 1104 responds to the MU-RTS at time t3 by transmitting CTS back to AP 1102.

[0143] In some implementations, the duration field of the MU-RTS frame (in the MAC header) can be used to protect time-delay-sensitive traffic in a restricted TWT SP. As described with reference to FIG8A, existing versions of STAs conforming to 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 longer than the duration required to transmit the MU-RTS frame. As shown in FIG11A, a non-traditional STA 1106 sets its NAV to the duration indicated by the duration field of the MU-RTS frame, which spans the duration from time t2 to t8. In some other implementations, a non-traditional STA 1106 may set its NAV to the duration indicated by the duration field of the CTS frame.

[0144] In some implementations, AP 1102 may transmit a trigger frame at time t5 after receiving a CTS frame. In some implementations, the trigger frame may request a TB PPDU from one or more low-latency STAs (such as low-latency STA 1104). As shown in FIG11A, low-latency STA 904 responds to the trigger frame at time t7 by transmitting UL data to AP 1102 in a TB PPDU.

[0145] At the end of the NAV duration, at time t8, the non-traditional STA 1106 can contend for media access. However, the non-traditional STA 1106 senses that the media is busy at time t8 due to the transmission of the TB PPDU. Therefore, the non-traditional STA 1106 avoids accessing the shared media during the duration of the TB PPDU. After the transmission of the TB PPDU has been completed, at time t9, the non-traditional STA 1106 can contend for media access again. As shown in Figure 11A, the non-traditional STA 1106 senses that the media is idle during the AIFS duration from time t9 to t10, counts down the RBO duration from time t10 to t11, and acquires the TXOP from time t11 to t12.

[0146] In some implementations, the MU-RTS can identify multiple low-latency STAs (not shown for simplicity). In this implementation, each low-latency STA can respond to the MU-RTS frame to transmit the corresponding CTS frame from time t3 to t4. In some other implementations, a trigger frame can be used to request TB PPDUs from multiple low-latency STAs (not shown for simplicity). In this implementation, multiple low-latency STAs can concurrently transmit the corresponding UL data (from time t7 to t9) to AP 1102 in TB PPDUs.

[0147] In some implementations, AP 1102 may poll low-latency STAs before the start of the restricted TWT SP to determine which STA (if any) has UL data to send. For example, AP 1102 may transmit a BSRP trigger frame to the low-latency STA associated with the restricted TWT SP. Each low-latency STA responds to the BSRP trigger frame by transmitting a BSR indicating the amount of UL data buffered by the STA back to AP 1102. AP 1102 may use the information carried in each BSR to determine resource allocation for the TB PPDU.

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

[0149] Figure 11B illustrates a timing diagram 1110 of an example of wireless communication between devices belonging to a BSS. In the example of Figure 11B, the BSS is illustrated as including AP 1112, low-latency STA 1114, and non-traditional STA 1116. Low-latency STA 1114 is a member of a restricted TWT SP (r-TWT SP) that spans a duration from time t0 to t12, while non-traditional STA 1116 is not a member of a restricted TWT SP. In some implementations, AP 1112 may be an instance of AP 110 of Figure 1 or AP 300 of Figure 3. In some implementations, each of STAs 1114 and 1116 may be an instance of any of STAs 120a-120i of Figure 1 or STA 200 of Figure 2. Although only one low-latency STA and one non-traditional STA are illustrated in the example of Figure 11B, in actual implementations, the BSS can include any number of low-latency STAs and any number of non-traditional STAs.

[0150] In some implementations, AP 1112 may transmit MU-RTS frames over the shared wireless medium at the start of the restricted TWT SP. More specifically, AP 1112 attempts to time the transmission of the MU-RTS frames to coincide with the start of the restricted TWT SP. In the example of Figure 11B, non-traditional STA 1116 acquires a truncated TXOP before the start of the restricted TWT SP. AP 1112 senses that the medium is idle for the PIFS duration from time t0 to t1 and continues transmitting MU-RTS frames at time t1. In some implementations, the MU-RTS frames may identify one or more low-latency STAs (such as low-latency STA 1114). As shown in Figure 11B, low-latency STA 1114 responds to the MU-RTS at time t3 by transmitting a CTS back to AP 1112.

[0151] In some implementations, the duration field of the MU-RTS frame (in the MAC header) can be used to protect time-delay-sensitive traffic in a restricted TWT SP. As described with reference to FIG8A, existing versions of STAs conforming to 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 longer than the duration required to transmit the MU-RTS frame. As shown in FIG11B, a non-traditional STA 1116 sets its NAV to the duration indicated by the duration field of the MU-RTS frame, which spans the duration from time t2 to t8. In some other implementations, a non-traditional STA 1116 may set its NAV to the duration indicated by the duration field of the CTS frame.

[0152] In some implementations, AP 1112 may transmit a trigger frame at time t5 after receiving a CTS frame. In some implementations, the trigger frame may request a TB PPDU from one or more low-latency STAs (such as low-latency STA 1114). As shown in FIG11B, low-latency STA 904 responds to the trigger frame at time t7 by transmitting UL data to AP 1112 in a TB PPDU.

[0153] At the end of the NAV duration, at time t8, the non-traditional STA 1116 can contend for media access. However, the non-traditional STA 1116 senses that the media is busy at time t8 due to the transmission of the TB PPDU. Therefore, the non-traditional STA 1116 avoids accessing the shared media during the duration of the TB PPDU. After the transmission of the TB PPDU has been completed, at time t9, the non-traditional STA 1116 can contend for media access again. As shown in Figure 11B, the non-traditional STA 1116 senses that the media is idle during the AIFS duration from time t9 to t10, counts down the RBO duration from time t10 to t11, and acquires the TXOP from time t11 to t12.

[0154] In some implementations, the MU-RTS can identify multiple low-latency STAs (not shown for simplicity). In this implementation, each low-latency STA can respond to the MU-RTS frame to transmit the corresponding CTS frame from time t3 to t4. In some other implementations, a trigger frame can be used to request TB PPDUs from multiple low-latency STAs (not shown for simplicity). In this implementation, multiple low-latency STAs can concurrently transmit the corresponding UL data (from time t7 to t9) to AP 1112 in TB PPDUs.

[0155] In some implementations, AP 1112 may poll low-latency STAs before the start of the restricted TWT SP to determine which STA (if any) has UL data to send. For example, AP 1112 may transmit a BSRP trigger frame to the low-latency STA associated with the restricted TWT SP. Each low-latency STA responds to the BSRP trigger frame by transmitting a BSR indicating the amount of UL data buffered by the STA back to AP 1112. AP 1112 may use the information carried in each BSR to determine the resource allocation for the TB PPDU.

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

[0157] Figure 12 illustrates an illustrative flowchart 1200 of an exemplary wireless communication operation. The exemplary operation 1200 can be performed by a wireless communication device, such as either AP 110 or 300 of Figures 1 and 3.

[0158] The wireless communication device performs a channel sensing operation (1202) indicating whether the wireless channel is busy or idle. The wireless communication device also responds to the channel sensing operation indicating that the wireless channel is idle for a threshold duration relative to the start of the restricted TWT SP by transmitting a first packet on the wireless channel associated with the restricted TWT SP at a first time, wherein the first packet includes a duration field indicating the duration for which the wireless channel is reserved, and wherein the channel sensing operation also indicates that the wireless channel is busy 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 (1204).

[0159] In some implementations, the wireless communication device may also receive a third packet from the second STA on the wireless channel at a third time, wherein the third time occurs after the second time and before the end of the restricted TWT SP. In some implementations, the first time may coincide with the start of the restricted 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 restricted TWT SP may be less than or equal to the threshold duration. In some implementations, the first packet may be a clear transmission CTS to its own frame.

[0160] In some implementations, the wireless communication device may also receive a second packet from a first STA associated with the restricted TWT SP on a wireless channel 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 also request second uplink data from a second STA associated with the restricted TWT SP, and the TB PPDU may also carry the second uplink data. In some implementations, the wireless communication device may also transmit a BSRP trigger frame to the first STA before the start of the restricted TWT SP, and may respond to the BSRP trigger frame to receive a BSR from the first STA, wherein the BSR indicates the availability of the first uplink data.

[0161] FIG13 illustrates an illustrative flowchart 1300 of an exemplary wireless communication operation. The exemplary operation 1300 can be performed by a wireless communication device, such as any of the STA 120a-120i of FIG1 or the STA 200 of FIG2.

[0162] The wireless communication device receives a first packet on a wireless channel associated with a restricted TWT SP at a first time, wherein the first packet includes a duration field (1302) indicating the duration for which the wireless channel is reserved. In some implementations, the first time may coincide with the start of the restricted 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 restricted TWT SP may be less than or equal to the PIFS duration. In some implementations, the first packet may be a CTS-to-self frame.

[0163] The wireless communication device also responds to the first packet to transmit a second packet on the wireless channel at a second time, wherein the second time is less than the duration indicated by the duration field of the first packet (1304) after the first time. 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 uplink data. In some implementations, the wireless communication device may also receive a BSRP trigger frame before the start of the restricted TWT SP and may respond to the BSRP trigger frame to transmit a BSR, wherein the BSR indicates the availability of uplink data.

[0164] FIG14 illustrates 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 FIG12. The wireless communication device 1400 may be an exemplary implementation of either AP 110 or 300 of FIG1 and FIG3, respectively. More specifically, the wireless communication device 1400 may be a chip, SoC, chipset, package, or device including at least one processor and at least one modem (e.g., a Wi-Fi (IEEE 802.11) modem or a cellular modem).

[0165] The wireless communication device 1400 includes a receiving element 1410, a communication manager 1420, and a transmitting element 1430. The communication manager 1420 also includes a channel sensing element 1422 and a time-delay-sensitive (LS) traffic protection element 1424. A portion of one or more of the elements 1422 or 1424 may be implemented at least partially in hardware or firmware. In some implementations, one or more of the elements 1422 or 1424 are at least partially implemented as software stored in memory (such as memory 240 of FIG. 2 or memory 330 of FIG. 3). For example, a portion of one or more of the elements 1422 or 1424 may be implemented as non-transitory instructions (or "code") executable by a processor (such as processor 320 of FIG. 3) to perform the function or operation of the corresponding element.

[0166] The receiving element 1410 is configured to receive RX signals from one or more other wireless communication devices, and the transmitting element 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 element 1422 may perform a channel sensing operation indicating whether the wireless channel is busy or idle; and the LS traffic protection element 1424 may, in response to the channel sensing operation indicating that the wireless channel is idle for a threshold duration relative to the start of the restricted TWT SP, transmit a first packet on the wireless channel associated with the restricted TWT SP at a first time, wherein the first packet includes a duration field indicating a duration reserved for the wireless channel, and wherein the channel sensing operation also indicates that the wireless channel is busy 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.

[0167] FIG15 illustrates 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 FIG13. The wireless communication device 1500 may be an exemplary implementation of any of the STA 120a-120i of FIG1 or the STA 200 of FIG2. More specifically, the wireless communication device 1500 may be a chip, SoC, chipset, package, or device including at least one processor and at least one modem (e.g., a Wi-Fi (IEEE 802.11) modem or a cellular modem).

[0168] The wireless communication device 1500 includes a receiving element 1510, a communication manager 1520, and a transmitting element 1530. The communication manager 1520 also includes a delay-sensitive (LS) traffic management element 1522. A portion of the LS traffic management element 1522 may be implemented, at least partially, in hardware or firmware. In some implementations, the LS traffic management element 1522 is at least partially implemented as software stored in memory (such as memory 240 of FIG. 2 or memory 330 of FIG. 3). For example, a portion of the LS traffic management element 1522 may be implemented as non-transitory instructions (or "code") executable by a processor (such as processor 220 of FIG. 2) to perform the function or operation of the corresponding element.

[0169] The receiving element 1510 is configured to receive an RX signal from one or more other wireless communication devices, and the transmitting element 1530 is configured to transmit a TX signal to one or more other wireless communication devices. In some implementations, the receiving element 1510 may receive a first packet on a wireless channel associated with a restricted TWT SP at a first time, wherein the first packet includes a duration field indicating the duration for which the wireless channel is reserved. In some implementations, the transmitting element 1530 may respond to the first packet by transmitting a second packet on the wireless channel 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.

[0170] Examples of implementations are described in the following numbered clauses: 1. A method for wireless communication performed by a wireless communication device, comprising the steps of: performing a channel sensing operation indicating whether a wireless channel is busy or idle; and in response to the channel sensing operation indicating that the wireless channel is idle for a threshold duration relative to the start of a restricted target wake-up time (TWT) service period (SP), transmitting a first packet on the wireless channel associated with the restricted TWT SP at a first time, the first packet including a duration field indicating a duration reserved for the wireless channel, the channel sensing operation also indicating that the wireless channel is busy 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. 2. The method of clause 1, wherein the first time coincides with the start of the restricted TWT SP. 3. The method of either clause 1 or 2, 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. 4. The method of any one of Clauses 1-3, wherein the threshold duration is the Point Coordination Function (PCF) Inter-Frame Space (PIFS) duration. 5. The method of any one of Clauses 1-4, wherein the duration between the first time and the start of the restricted TWT SP is less than or equal to the threshold duration. 6. The method of any one of Clauses 1-5, further comprising the step of: receiving a second packet on the radio channel from a first radio station (STA) associated with the restricted TWT SP at the second time. 7. The method of any one of Clauses 1-6, wherein the first packet includes a Clear Transmission (CTS) to itself frame. 8. The method of any one of Clauses 1-6, wherein the first packet includes a Multi-User (MU) Request Transmission (RTS) frame, and the second packet includes a CTS frame. 9. The method of any one of Clauses 1-6, wherein the first packet includes a trigger frame requesting first uplink data from the first STA, and the second packet is a Triggered (TB) Entity Layer Convergence Protocol (PLCP) Protocol Data Unit (PPDU) carrying the first uplink data. 10. The method of any one of Clauses 1-6 or 9, wherein the trigger frame also requests second uplink data from a second STA associated with the restricted TWT SP, and the TB PPDU also carries the second uplink data. 11. The method of any one of Clauses 1-6, 9, or 10, also includes the steps of: transmitting a Buffer Status Report Polling (BSRP) trigger frame to the first STA prior to the start of the restricted TWT SP; and receiving a Buffer Status Report (BSR) from the first STA in response to the BSRP trigger frame, the BSR indicating the availability of the first uplink data.12. The method according to any one of Clauses 1-11 also includes the step of: receiving a third packet from a second STA on the wireless channel at a third time, the third time occurring after the second time and before the end of the restricted TWT SP. 13. A wireless communication device comprising: a processing system configured to: perform a channel sensing operation indicating whether a wireless channel is busy or idle; and at least one interface configured to: in response to the channel sensing operation indicating that the wireless channel is idle for a threshold duration relative to the start of a restricted target wake-up time (TWT) service period (SP), transmit a first packet on the wireless channel associated with the restricted TWT SP at a first time, the first packet including a duration field indicating a duration reserved for the wireless channel, the channel sensing operation also indicating that the wireless channel is busy 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. 14. The wireless communication device according to Clause 13, wherein the first packet includes a clear transmit (CTS) to its own frame. 15. The wireless communication device according to Clause 13, wherein the at least one interface is also configured to receive a second packet on the wireless channel at the second time from a wireless station (STA) associated with the restricted TWT SP, the first packet including a Multiple User (MU) Request to Transmit (RTS) frame, and the second packet including a CTS frame. 16. The wireless communication device according to Clause 13, wherein the at least one interface is also configured to receive a second packet on the wireless channel at the second time from a STA associated with the restricted TWT SP, the first packet including a trigger frame requesting uplink data from the STA, and the second packet being a Triggered-Based (TB) Entity Layer Convergence Protocol (PLCP) Protocol Data Unit (PPDU) carrying the uplink data. 17. A method performed by a wireless communication device, comprising the steps of: receiving a first packet at a first time on a wireless channel associated with a restricted target wake-up time (TWT) service period (SP), the first packet including a duration field indicating a duration reserved for the wireless channel; and responding to the first packet to transmit a second packet on the wireless channel 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. 18. The method of claim 17, wherein the first time coincides with the start of the restricted TWT SP. 19. The method of claim 17 or 18, 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.20. The method of any one of Clauses 17-19, wherein the duration between the first time and the start of the restricted TWT SP is less than or equal to the Point Coordination Function (PCF) Inter-Frame Space (PIFS) duration. 21. The method of any one of Clauses 17-20, wherein the first packet includes a Clear Transmission (CTS) frame to itself. 22. The method of any one of Clauses 17-20, wherein the first packet includes a Multi-User (MU) Request Transmission (RTS) frame, and the second packet includes a CTS frame. 23. The method of any one of Clauses 17-20, wherein the first packet includes a trigger frame requesting uplink data from the wireless communication device, and the second packet is a Triggered-Based (TB) Entity Layer Convergence Protocol (PLCP) Protocol Data Unit (PPDU) carrying the uplink data. 24. The method according to any one of Clauses 17-20 or 23 also includes the following steps: receiving a Buffer Status Report Polling (BSRP) trigger frame prior to the start of the restricted TWT SP; and transmitting a Buffer Status Report (BSR) in response to the BSRP trigger frame, the BSR indicating the availability of the uplink data. 25. The method according to any one of Clauses 17-24, wherein the second packet is transmitted to an Access Point (AP). 26. The method according to any one of Clauses 17-24, wherein the second packet is transmitted to a Radio Station (STA). 27. A wireless communication device, comprising: a processing system; and an interface configured to: receive a first packet at a first time on a wireless channel associated with a Restricted Target Wake-up Time (TWT) service period (SP), the first packet including a duration field indicating a duration reserved for the wireless channel; and respond to the first packet to transmit a second packet on the wireless channel 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. 28. The wireless communication device of claim 27, wherein the first packet includes a Clear Transmit (CTS) to Self frame. 29. The wireless communication device of claim 27, wherein the first packet includes a Multiple User (MU) Request Transmit (RTS) frame, and the second packet includes a CTS frame. 30. A wireless communication device pursuant to Clause 27, wherein the first packet includes a trigger frame requesting uplink data from the wireless communication device, and the second packet is a trigger-based (TB) Entity Layer Convergence Protocol (PLCP) Protocol Data Unit (PPDU) carrying the uplink data.

[0171] As used herein, the phrase “at least one of” or “one or more of” in the list of projects means any combination of those projects, including a single member. For example, “at least one of the following: a, b or c” is intended to cover the possibility of: only a, only b, only c, a combination of a and b, a combination of a and c, a combination of b and c, and a combination of a, b and c.

[0172] The various illustrative elements, logic, logic blocks, modules, circuits, operations, and algorithmic processes described in conjunction with the implementation methods disclosed herein can be implemented as electronic hardware, firmware, software, or a combination of hardware, firmware, or software, including the structures and their equivalents disclosed in this specification. The interchangeability of hardware, firmware, and software has been described in the functional sample as a whole and illustrated in the various illustrative elements, blocks, modules, circuits, and processes described above. Whether such functionality is implemented in hardware, firmware, or software depends on the specific application and the design constraints imposed on the overall system.

[0173] Various modifications to the implementations described herein will be obvious to a person skilled in the art, and the general principles defined herein can be applied to other implementations without departing from the spirit or scope of this document. Therefore, the claim is not intended to be limited to the implementations shown herein, but rather to be given the broadest scope consistent with the content of this document and the principles and novel features disclosed herein.

[0174] Furthermore, the various features described in this specification in the context of separate implementations can also be implemented in combination in a single implementation. Conversely, the various features described in the context of a single implementation can also be implemented individually or in any suitable sub-combination in multiple implementations. Therefore, although features may be described above as taking action in a specific combination, and even initially claimed in this manner, in some cases, one or more features from the claimed combination can be removed from that combination, and the claimed combination can be for sub-combinations or variations thereof.

[0175] Similarly, although operations are illustrated in a specific order in the accompanying drawings, this should not be construed as requiring that such operations be performed in the specific illustrated order or sequential order, or requiring that all illustrated operations be performed to achieve the desired result. Furthermore, the drawings may schematically illustrate one or more exemplary processes in the form of flowcharts or schematic diagrams. However, other operations not illustrated may be incorporated into the schematically illustrated exemplary processes. For example, one or more additional operations may be performed before, after, simultaneously with, or between any of the illustrated operations. In some cases, multiplexing and parallel processing may be advantageous. Moreover, the separation of various system elements in the implementations described above should not be construed as requiring such separation in all implementations, and it should be understood that the described program elements and systems can generally be integrated together in a single software product or encapsulated in multiple software products. [Simplified Explanation of the Diagram]

[0011] Figure 1 illustrates a block diagram of an exemplary wireless system.

[0012] Figure 2 illustrates a block diagram of an exemplary wireless station (STA).

[0013] Figure 3 illustrates a block diagram of an exemplary access point (AP).

[0014] Figure 4A illustrates a timing diagram of an example of wireless communication between devices belonging to a Basic Service Set (BSS).

[0015] Figure 4B illustrates a timing diagram of an example of wireless communication between devices belonging to the BSS.

[0016] Figure 4C illustrates a timing diagram of an example of wireless communication between devices belonging to the BSS.

[0017] Figure 5 illustrates a timing diagram of an example of wireless communication between devices belonging to the BSS.

[0018] Figure 6 illustrates a timing diagram of an example of wireless communication between devices belonging to the BSS.

[0019] Figure 7 illustrates a timing diagram of an example of wireless communication between devices belonging to the BSS.

[0020] Figure 8A illustrates a timing diagram of an example of wireless communication between devices belonging to the BSS.

[0021] Figure 8B illustrates a timing diagram of an example of wireless communication between devices belonging to the BSS.

[0022] Figure 9A illustrates a timing diagram of an example of wireless communication between devices belonging to the BSS.

[0023] Figure 9B illustrates a timing diagram of an example of wireless communication between devices belonging to the BSS.

[0024] Figure 10A illustrates a timing diagram of an example of wireless communication between devices belonging to the BSS.

[0025] Figure 10B illustrates a timing diagram of an example of wireless communication between devices belonging to the BSS.

[0026] Figure 11A illustrates a timing diagram of an example of wireless communication between devices belonging to the BSS.

[0027] Figure 11B illustrates a timing diagram of an example of wireless communication between devices belonging to the BSS.

[0028] Figure 12 illustrates an illustrative flowchart of an exemplary wireless communication operation.

[0029] Figure 13 illustrates an illustrative flowchart of an exemplary wireless communication operation.

[0030] Figure 14 illustrates a block diagram of an exemplary wireless communication device.

[0031] Figure 15 illustrates a block diagram of an exemplary wireless communication device.

[0032] Similar element symbols and naming indications in the various figures indicate similar elements. [Biomaterial Storage]

[0177] Domestic storage information (please note in order of storage institution, date, and number): None. International storage information (please note in order of storage country, institution, date, and number): None.

Claims

1. A method performed by a wireless communication device, comprising the steps of: performing a channel sensing operation indicating whether a wireless channel is busy or idle; and in response to the channel sensing operation indicating that the wireless channel is idle for a threshold duration relative to the beginning of a restricted target wake-up time (TWT) service period (SP), transmitting a first packet on a wireless channel associated with the restricted TWT SP at a first time, the first packet including a duration field indicating that the wireless channel is reserved for a duration, wherein the duration corresponds to a first portion of the restricted TWT SP, wherein a second portion of the restricted TWT SP following the first portion is available for contention by any one of one or more first devices that are members of the restricted TWT SP and one or more second devices that are non-members of the restricted TWT SP.

2. According to the method of request item 1, wherein the first time coincides with the start of the restricted TWT SP.

3. The method of request item 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. According to the method of request item 1, wherein the threshold duration is the One Point Coordination Function (PCF) Frame Space (PIFS) duration.

5. According to the method of request item 1, wherein a third duration between the first time and the start of the restricted TWT SP is less than or equal to the threshold duration.

6. According to the method of request item 1, wherein the first packet includes a clear send (CTS) to itself frame.

7. The method according to claim 1 also includes the following steps: receiving a second packet on the wireless channel at the second time from a first wireless station (STA) associated with the restricted TWT SP.

8. The method according to request item 7, wherein the first packet includes a Multi-User (MU) Request to Send (RTS) frame and the second packet includes a CTS frame.

9. The method of request item 7, wherein the first packet includes a trigger frame requesting first uplink data from the first STA, and the second packet is a trigger-based (TB) Entity Layer Convergence Protocol (PLCP) Protocol Data Unit (PPDU) carrying the first uplink data.

10. The method according to claim 1 also includes the following steps: receiving a third packet from a second STA on the wireless channel at a third time, the third time occurring after the second time and before the end of the restricted TWT SP.

11. The method according to claim 1 also includes the following steps: sending a quiet element indicating a quiet duration associated with the start of the restricted TWT SP, the quiet element indicating that the one or more second devices that are non-members of the restricted TWT SP are restricted from contention for access to the radio channel during the quiet duration.

12. A wireless communication device, comprising: A processing system comprising one or more processors configured to: perform a channel sensing operation indicating whether a wireless channel is busy or idle; and at least one interface configured to: in response to the channel sensing operation indicating that the wireless channel is idle for a threshold duration relative to the beginning of a restricted target wake-up time (TWT) service period (SP), transmit a first packet on a wireless channel associated with the restricted TWT SP at a first time, the first packet including a duration field indicating that the wireless channel is reserved for a duration, wherein the duration corresponds to a first portion of the restricted TWT SP, wherein a second portion of the restricted TWT SP following the first portion is available for contention by any one of one or more first devices that are members of the restricted TWT SP and one or more second devices that are non-members of the restricted TWT SP.

13. The wireless communication device according to claim 12, wherein the first packet includes a clear transmission (CTS) to its own frame.

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

15. The wireless communication device according to claim 12, wherein the at least one interface is also configured to: receive a second packet on the wireless channel at the second time from a STA associated with the restricted TWT SP, the first packet including a trigger frame requesting uplink data from the STA, the second packet being a trigger-based (TB) Entity Layer Convergence Protocol (PLCP) Protocol Data Unit (PPDU) carrying the uplink data.

16. A method performed by a wireless communication device, comprising the steps of: receiving a first packet at a first time on a wireless channel associated with a restricted target wake-up time (TWT) service period (SP), the first packet including a duration field indicating that the wireless channel is reserved for a duration, wherein the duration corresponds to a first portion of the restricted TWT SP, wherein a second portion of the restricted TWT SP following the first portion is available for contention by any one of one or more first devices that are members of the restricted TWT SP and one or more second devices that are non-members of the restricted TWT SP; and in response to the first packet transmitting a second packet at a second time on the wireless channel, the second time occurring at least in part within the first portion of the restricted TWT SP based on the wireless communication device being a member of the restricted TWT SP.

17. The method of request item 16, wherein the first moment coincides with the beginning of the restricted TWT SP.

18. The method of request item 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 of request item 16, wherein a third duration between the first time and the beginning of the restricted TWT SP is less than or equal to the duration of the point coordination function (PCF) inter-frame space (PIFS).

20. The method of request item 16, wherein the first packet includes a clear send (CTS) to itself frame.

21. The method according to request item 16, wherein the first packet includes a Multi-User (MU) Request to Send (RTS) frame, and the second packet includes a CTS frame.

22. The method of claim 16, wherein the first packet includes a trigger frame requesting uplink data from the wireless communication device, and the second packet is a trigger-based (TB) Entity Layer Convergence Protocol (PLCP) Protocol Data Unit (PPDU) carrying the uplink data.

23. The method according to request item 22 also includes the following steps: receiving a Buffer Status Report Polling (BSRP) trigger frame before the start of the restricted TWT SP; and transmitting a Buffer Status Report (BSR) in response to the BSRP trigger frame, the BSR indicating the availability of the uplink data.

24. According to the method of request item 16, wherein the second packet is transmitted to an access point (AP).

25. The method of request item 16, wherein the second packet is transmitted to a wireless station (STA).

26. The method according to claim 16 also includes the following steps: sending a quiet element indicating a quiet duration associated with the start of the restricted TWT SP, the quiet element indicating that the one or more second devices that are non-members of the restricted TWT SP are restricted from contention for access to the radio channel during the quiet duration.

27. A wireless communication device, comprising: A processing system comprising one or more processors; and an interface configured to: receive a first packet at a first time on a wireless channel associated with a restricted target wake-up time (TWT) service period (SP), the first packet including a duration field indicating that the wireless channel is reserved for a duration, wherein the duration corresponds to a first portion of the restricted TWT SP, wherein a second portion of the restricted TWT SP following the first portion is available for contention by any one of one or more first devices that are members of the restricted TWT SP and one or more second devices that are non-members of the restricted TWT SP; and in response to the first packet transmit a second packet at a second time on the wireless channel, the second time occurring at least in part within the first portion of the restricted TWT SP based on the wireless communication device being a member of the restricted TWT SP.

28. The wireless communication device according to claim 27, wherein the first packet includes a clear transmission (CTS) to its own frame.

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

30. The wireless communication device according to claim 27, wherein the first packet includes a trigger frame requesting uplink data from the wireless communication device, and the second packet is a trigger-based (TB) Entity Layer Convergence Protocol (PLCP) Protocol Data Unit (PPDU) carrying the uplink data.

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