Systems and Computer-Readable Media for Quiet Time Interval Termination

Abstract

An access point (AP) transmits a first frame, the first frame including: a Target Wake Time (TWT) element indicating an r-TWT service period (SP) of a restricted Target Wake Time (r-TWT) set for one or more first stations (STAs); and a silent element indicating a silent time interval for one or more second STAs, the silent time interval overlapping with a part of the r-TWT SP. Based on determining that the r-TWT SP terminates during the silent time interval, the AP transmits a second frame during the silent time interval, the second frame indicating the termination of the silent time interval for the one or more second STAs.

Description

[0001] Cross - Reference to Related Applications

[0002] This application claims the benefit of U.S. Provisional Application No. 63 / 241,299, filed on September 7, 2021, which is hereby incorporated by reference in its entirety. BRIEF DESCRIPTION OF THE DRAWINGS

[0003] Examples of several embodiments of the present disclosure are described herein with reference to the drawings.

[0004] Figure 1 An example wireless communication network is shown in which embodiments of the present disclosure may be implemented.

[0005] Figure 2 is a block diagram showing an example implementation of a station (STA) and an access point (AP).

[0006] Figure 3 An example of a Target Wake Time (TWT) operation is shown.

[0007] Figure 4 An example of a TWT operation in an environment including an AP Multi - Link Device (AP MLD) and a Station Multi - Link Device (STA MLD) is shown.

[0008] Figure 5 An example TWT element that can be used to support individual TWT operations is shown.

[0009] Figure 6 An example TWT element that can be used to support Restricted TWT (r - TWT) operations is shown.

[0010] Figure 7 An example of an individual TWT operation is shown.

[0011] Figure 8 An example of a broadcast TWT operation is shown.

[0012] Figure 9 An example of TWT protection in an individual TWT operation is shown.

[0013] Figure 10 An example of a restricted TWT operation is shown.

[0014] Figure 11 An example silence element that can be used to support silence interval operations is shown.

[0015] Figure 12 An example of a silence interval operation is shown.

[0016] Figure 13 An example including rescheduling a silence interval is shown.

[0017] Figure 14 Shows an example including the silent time interval terminated by the AP.

[0018] Figure 15 Shows another example including the silent time interval terminated by the AP.

[0019] Figure 16 Shows an example of an aggregation control (A control) field that can be used to indicate the termination of the silent time interval.

[0020] Figure 17 Shows an example process according to an embodiment.

[0021] Figure 18 Shows another example process according to an embodiment.

[0022] Figure 19 Shows another example process according to an embodiment. Detailed Description

[0023] In the present disclosure, various embodiments are presented in the form of examples of how the disclosed technology can be implemented and / or how the disclosed technology can be practiced in an environment and scenario. It will be apparent to those skilled in the relevant art that various changes in form and detail can be made therein without departing from the scope. After reading this specification, it will be apparent to those skilled in the relevant art how to implement alternative embodiments. The embodiments of the present invention shall not be limited by any of the described exemplary embodiments. The embodiments of the present disclosure will be described with reference to the accompanying drawings. Limitations, features, and / or elements from the disclosed exemplary embodiments can be combined to create additional embodiments within the scope of the present disclosure. Any figures highlighting functionality and advantages are presented for illustrative purposes only. The disclosed architecture is flexible enough and configurable such that it can be utilized in a manner different from the way shown. For example, in some embodiments, the actions listed in any flowchart can be reordered or used only optionally.

[0024] Embodiments can be configured to operate as needed. When certain criteria are met, the disclosed mechanisms can be executed, for example, in a station, an access point, a radio environment, a network, a combination of the above, etc. Example criteria can be at least partially based on, for example, wireless device or network node configuration, traffic load, initial system settings, packet size, traffic characteristics, a combination of the above, etc. When one or more criteria are met, various example embodiments can be applied. Thus, example embodiments that selectively implement the disclosed protocol can be implemented.

[0025] In the present disclosure, the phrases "a" and "an" and similar phrases will be interpreted as "at least one" and "one or more". Similarly, any term ending with the suffix "(s)" will be interpreted as "at least one" and "one or more". In the present disclosure, the term "may" is interpreted as "may, for example". In other words, the term "may" indicates that the phrase following the term "may" is an instance of one of the various suitable possibilities that may or may not be used in one or more of the respective embodiments. As used herein, the terms "comprising" and "consisting of" enumerate one or more components of the described element. The term "comprising" is used interchangeably with "including" and does not exclude unenumerated components from being included in the described element. In contrast, "consisting of" provides a complete enumeration of one or more components of the described element. As used herein, the term "based on" can be interpreted as "at least partially based on" rather than, for example, "only based on". As used herein, the term "and / or" represents any possible combination of the enumerated elements. For example, "A, B, and / or C" can represent A; B; C; A and B; A and C; B and C; or A, B, and C.

[0026] If A and B are sets and every element of A is also an element of B, then A is called a subset of B. In this specification, only non-empty sets and subsets are considered. For example, the possible subsets of B = {STA1, STA2} are: {STA1}, {STA2}, and {STA1, STA2}. The phrase "based on" (or equivalently "at least based on") indicates that the phrase following the term "based on" is an instance of one of the various suitable possibilities that may or may not be used in one or more of the respective embodiments. The phrase "in response to" (or equivalently "at least in response to") indicates that the phrase following the phrase "in response to" is an instance of one of the various suitable possibilities that may or may not be used in one or more of the respective embodiments. The phrase "depending on" (or equivalently "at least depending on") indicates that the phrase following the phrase "depending on" is an instance of one of the various suitable possibilities that may or may not be used in one or more of the respective embodiments. The phrase "employ / use" (or equivalently "at least employ / use") indicates that the phrase following the phrase "employ / use" is an instance of one of the various suitable possibilities that may or may not be used in one or more of the respective embodiments.

[0027] The term "configured" can relate to the capabilities of a device, whether the device is in an operating state or a non-operating state. "Configured" can refer to specific settings within a device that affect the operating characteristics of the device, whether the device is in an operating state or a non-operating state. In other words, hardware, software, firmware, registers, memory values, etc. can be "configured" within a device, whether the device is in an operating state or a non-operating state, to provide the device with specific characteristics. Terms such as "control message for causing... in a device" can mean that the control message has parameters that can be used to configure specific characteristics or can be used to perform some action in a device, whether the device is in an operating state or a non-operating state.

[0028] In the present disclosure, a parameter (or equivalently referred to as a field or information element: IE) can include one or more information objects, and an information object can include one or more other objects. For example, if parameter (IE) N includes parameter (IE) M, and parameter (IE) M includes parameter (IE) K, and parameter (IE) K includes parameter (information element) J. Then, for example, N includes K, and N includes J. In an exemplary embodiment, when one or more messages / frames include multiple parameters, this means that the parameters among the multiple parameters are in at least one of the one or more messages / frames, but not necessarily in each of the one or more messages / frames.

[0029] Many of the features presented are described as being optional by using "may" or by using parentheses. For the sake of brevity and readability, the present disclosure does not explicitly recite every permutation that can be obtained by making selections from the set of optional features. The present disclosure should be construed as explicitly disclosing all such permutations. For example, a system described as having three optional features can be embodied in seven ways, namely having only one of the three possible features, having any two of the three possible features, or having all three of the three possible features.

[0030] Many of the elements described in the disclosed embodiments can be implemented as modules. A module is defined herein as an element that performs a defined function and has a defined interface to other elements. The modules described in the present disclosure can be implemented in hardware, software and hardware, firmware, wetware (e.g., hardware with biological elements), or a combination thereof, which can be behaviorally equivalent. For example, a module can be implemented as a software routine written in a computer language, which is configured to be executed by a hardware machine (such as C, C++, Fortran, Java, Basic, Matlab, etc.) or a modeling / simulation program (such as Simulink, Stateflow, GNU Octave, or LabVIEW MathScript). A physical hardware combined with discrete or programmable analog, digital, and / or quantum hardware can be used to implement a module. Examples of programmable hardware include: computers, microcontrollers, microprocessors, application-specific integrated circuits (ASICs); field-programmable gate arrays (FPGAs); and complex programmable logic devices (CPLDs). Computers, microcontrollers, and microprocessors are programmed using languages such as assembly, C, C++. FPGAs, ASICs, and CPLDs are typically programmed using a hardware description language (HDL) such as VHSIC Hardware Description Language (VHDL) or Verilog, which configure the connections between internal hardware modules with fewer functions on programmable devices. The techniques mentioned are typically used in combination to achieve the results of functional modules.

[0031] Figure 1 An example wireless communication network is shown in which embodiments of the present disclosure can be implemented.

[0032] As Figure 1 shown, the example wireless communication network can include an Institute of Electrical and Electronics Engineers (IEEE) 802.11 (WLAN) infrastructure network 102. The WLAN infrastructure network 102 can include one or more basic service sets (BSSs) 110 and 120 and a distribution system (DS) 130.

[0033] Each of BSSs 110-1 and 110-2 includes a set of access points (APs or AP STAs) and at least one station (STA or non-AP STA). For example, BSS 110-1 includes AP 104-1 and STA 106-1, and BSS 110-2 includes AP 104-2 and STAs 106-2 and 106-3. The APs and at least one STA in a BSS perform an association procedure for communicating with each other.

[0034] The DS 130 can be configured to connect to BSS 110-1 and BSS 110-2. Thus, the DS 130 can enable an Extended Service Set (ESS) 150. Within the ESS 150, the APs 104-1 and 104-2 are connected via the DS 130 and can have the same Service Set Identifier (SSID).

[0035] The WLAN infrastructure network 102 can be coupled to one or more external networks. For example, as Figure 1 shown, the WLAN infrastructure network 102 can be connected to another network 108 (e.g., 802.X) via a portal 140. The portal 140 can act as a bridge connecting the DS 130 of the WLAN infrastructure network 102 to the other network 108.

[0036] Figure 1 The illustrated example wireless communication network can further include one or more ad-hoc networks or Independent BSSs (IBSSs). An ad-hoc network or IBSS is a network that includes multiple STAs within each other's communication range. The multiple STAs are configured such that they can communicate with each other using direct peer-to-peer communication (i.e., without going through an AP).

[0037] For example, in Figure 1 , the STAs 106-4, 106-5, and 106-6 can be configured to form a first IBSS 112-1. Similarly, the STAs 106-7 and 106-8 can be configured to form a second IBSS 112-2. Since an IBSS does not include an AP, it does not include a centralized management entity. Instead, the STAs within an IBSS are managed in a distributed manner. The STAs forming an IBSS can be fixed or mobile.

[0038] A STA acting as a predefined functional medium can include a Medium Access Control (MAC) layer compliant with the IEEE 802.11 standard. The physical layer interface of the radio medium can be used in both APs and non-AP stations (STAs). A STA can also be represented using various other terms, including mobile terminal, wireless device, wireless transmit / receive unit (WTRU), user equipment (UE), mobile station (MS), mobile subscriber unit, or user. For example, the term "user" can be used to represent a STA participating in uplink multi-user multiple-input, multiple-output (MU MIMO) and / or uplink orthogonal frequency division multiple access (OFDMA) transmissions.

[0039] A Physical Layer (PHY) Protocol Data Unit (PPDU) can be a composite structure that includes a PHY preamble and a payload in the form of a PHY Service Data Unit (PSDU). For example, the PSDU can include a PHY preamble and a header and / or one or more MAC Protocol Data Units (MPDUs). Information provided in the PHY preamble can be used by a receiving device to decode subsequent data in the PSDU. In the case where the PPDU is transmitted over a bonded channel (a channel formed by channel bonding), the preamble field can be replicated and transmitted in each of the multiple constituent channels. The PHY preamble can include both a legacy portion (or "legacy preamble") and a non-legacy portion (or "non-legacy preamble"). The legacy preamble can be used for purposes such as packet detection, automatic gain control, and channel estimation. The legacy preamble is also typically used to maintain compatibility with legacy devices. The format, encoding, and information provided in the non-legacy portion of the preamble are based on the specific IEEE802.11 protocol to be used for transmitting the payload.

[0040] A frequency band can include one or more sub-bands or frequency channels. For example, PPDUs compliant with the IEEE 802.11n, 802.11ac, 802.11ax, and / or 802.11be standard amendments can be transmitted over the 2.4 GHz, 5 GHz, and / or 6 GHz frequency bands, each of which can be divided into multiple 20 MHz channels. A PPDU can be transmitted over a physical channel with a minimum bandwidth of 20 MHz. Larger channels can be formed by channel bonding. For example, a PPDU can be transmitted over a physical channel with a bandwidth of 40 MHz, 80 MHz, 160 MHz, or 320 MHz by bonding multiple 20 MHz channels together.

[0041] Figure 2 is a block diagram showing an example implementation of STA 210 and AP 260.

[0042] As Figure 2 shown, STA 210 can include at least one processor 220, a memory 230, and at least one transceiver 240. AP 260 can include at least one processor 270, a memory 280, and at least one transceiver 290. Processors 220 / 270 can be operatively connected to transceivers 240 / 290.

[0043] Transceivers 240 / 290 can be configured to transmit / receive radio signals. In an embodiment, transceivers 240 / 290 can implement the PHY layer of the corresponding device (STA 210 or AP 260).

[0044] In an embodiment, STA 210 and / or AP 260 may be multi-link devices (MLDs), i.e., devices capable of operating on multiple links defined by the IEEE 802.11be standard amendment. Thus, STA 210 and / or AP 260 may each have multiple PHY layers. One or more of the transceivers 240 / 290 may be used to implement the multiple PHY layers.

[0045] Processor 220 / 270 may implement the functions of the PHY layer, MAC layer, and / or logical link control (LLC) layer of the corresponding device (STA 210 or AP 260).

[0046] Processor 220 / 270 and / or transceiver 240 / 290 may include application-specific integrated circuits (ASICs), other chip sets, logic circuits, and / or data processors. Memory 230 / 280 may include read-only memory (ROM), random access memory (RAM), flash memory, memory cards, storage media, and / or other storage units.

[0047] When an embodiment is executed by software, the techniques (or methods) described herein may be performed by modules (e.g., procedures, functions, etc.) that perform the functions described herein. The modules may be stored in memory 230 / 280 and executed by processor 220 / 270. Memory 230 / 280 may be implemented (or located) within or external to processor 220 / 270. Memory 230 / 280 may be operatively connected to processor 220 / 270 in various ways known in the art.

[0048] The feature Target Wake Time (TWT) introduced in the IEEE 802.11ah standard allows STAs to manage the activities in a BSS by scheduling STAs to operate at different times to reduce contention. TWT may allow STAs to reduce the amount of time that STAs using power management modes may need to wake up. TWT may be either individual TWT or broadcast TWT. Individual TWT follows a negotiated TWT protocol between STAs. Broadcast TWT is based on a schedule and provided by the AP to the STAs.

[0049] In individual TWT, the STA that requests the TWT protocol is called the TWT request STA. For example, the TWT request STA may be a non-AP STA. The STA that responds to the request is called the TWT response STA. For example, the TWT response STA may be an AP. The TWT request STA is assigned a specific time to wake up the frame and exchange the frame with the TWT response STA. The TWT request STA may transmit wake-up scheduling information to the TWT response STA. When a TWT protocol is established between the two, the TWT response STA may transmit the TWT value to the TWT request STA.

[0050] When explicit TWT is adopted, the TWT-requesting STA can wake up and perform frame exchanges. The TWT-requesting STA can receive the next TWT information in the response from the TWT-replying STA. When implicit TWT is used, the TWT-requesting STA can calculate the next TWT by adding a fixed value to the current TWT value.

[0051] The TWT value of implicit TWT can be periodic. The TWT-requesting STA operating according to the implicit TWT protocol can determine the start time of the next TWT service period (TWT SP) by adding the value of the TWT wake-up time interval associated with the TWT protocol to the start time value of the current TWT SP. The TWT-replying STA can include the start times of a series of TWT SPs corresponding to a single TWT flow identifier of the implicit TWT protocol in the target wake-up time field of the TWT element. The TWT element can include the value of 'Accept TWT' in the TWT setup command field. The start time of the TWT SP series can indicate the start time of the first TWT SP in the series. The start time of subsequent TWT SPs can be determined by adding the value of the TWT wake-up time interval to the start time of the current TWT SP. In an instance, after the TWT SP has passed or after receiving the end-of-service-period (EOSP) field equal to 1 from the TWT-replying STA (whichever occurs first), the TWT-requesting STA woken up for the implicit TWT SP can enter the doze state.

[0052] A TWT session can be negotiated between the AP and the STA. The TWT session can configure the TWT SPs for the DL and UL traffic between the AP and the STA. The expected traffic may be limited by the negotiated SPs. The TWT SP can start at a specific time. The TWT SP can run for the SP duration. The TWT SP can repeat every SP time interval.

[0053] Figure 3 An example 300 of TWT operation is shown. As Figure 3 shown, example 300 includes an AP 311, a STA 312, and a STA 313. The AP 311 and the STA 312 can establish a TWT SP 320. The AP 311 and the STA 313 can establish a TWT SP 321. The TWT SPs 320 and 321 can repeat as Figure 3 shown, such that the TWT SP 320 can include a first TWT SP 320-1 and a second TWT SP 320-2, and such that the TWT SP 321 can include a first TWT SP 321-1 and a second TWT SP 321-2.

[0054] AP 311 and STA 312 can exchange frames during the first TWT SP 320-1. STA 312 can enter the doze state at the end of TWT SP320-1 and can remain in the doze state until the start of the second TWT SP 320-2. The start of the second TWT SP 320-2 can be indicated by the TWT wake-up time interval 330 associated with TWT SP 320. AP 311 and STA 312 can exchange frames again during the second TWT SP 320-2.

[0055] Similarly, AP 311 and STA 313 can exchange frames during the first TWT SP 321-1. STA 313 can enter the doze state at the end of the first TWT SP 321-1 and can remain in the doze state until the start of the second TWT SP 321-2. The start of the second TWT SP 321-2 can be indicated by the TWT wake-up time interval 331 associated with TWT SP 321. AP 311 and STA 313 can exchange frames again during the second TWT SP 31-2.

[0056] In the wake state, the STA can be fully powered. The STA can transmit and / or receive frames to / from the AP or another STA. In the doze state, the STA may not transmit / receive frames to / from the AP or another STA.

[0057] The MLD is an entity capable of managing communications over multiple links. The MLD can be a logical entity and can have more than one attached station (STA). The MLD can have a single MAC service access point (MAC-SAP) to the LLC layer that includes the MAC data service. When the STA attached to the MLD is an AP STA (or AP), the MLD can be an access point MLD (AP MLD). When the STA attached to the MLD is a non-AP STA (or STA), the MLD can be a non-access point MLD (non-AP MLD).

[0058] During the negotiation of the TWT protocol, the TWT request STA attached to the STA MLD and the TWT response STA attached to the AP MLD can transmit multiple TWT elements. The TWT elements can include a link ID bitmap subfield indicating different links in the TWT setup frame. The TWT parameters provided by the TWT elements can be applied to the corresponding links indicated in the TWT elements.

[0059] Figure 4 An example 400 of TWT operation in a multi-link environment including an AP multi-link device (AP MLD) 410 and a STA multi-link device (STA MLD) 420 is shown. As Figure 4As shown, the AP MLD 410 may have three attached APs, namely AP 411, AP2 412, and AP3 413. In an example, AP 411, AP2 412, and AP3 413 may operate on the 2.4 GHz band, 5 GHz band, and 6 GHz band, respectively. The STA MLD 420 may have three attached STAs, namely STA 421, STA 422, and STA 423. In an example, STA 421, STA 422, and STA 423 may operate on the 2.4 GHz band, 5 GHz band, and 6 GHz band, respectively. In an example, AP 411, AP2 412, and AP3 413 may be communicatively coupled to STA 421, STA 422, and STA 423 via a first link (Link 1), a second link (Link 2), and a third link (Link 3), respectively.

[0060] In an example, STA 421 may transmit a TWT request to AP 411. The TWT request may include three TWT elements. Each TWT element may indicate a respective one of Links 1 - 3 and may request setting the TWT protocol for the indicated link. These three TWT elements may have different TWT parameters, such as a Target Wake Time (TWT). In response to the TWT request, AP 411 may transmit a TWT response to STA 421. The TWT response may include three TWT elements. Each TWT element may indicate a respective one of Links 1 - 3 and may include a value of 'Accept TWT' in the TWT setup command field.

[0061] Successful TWT protocol setup on Links 1 - 3 respectively establishes three TWT SPs with the same or different TWT parameters on Links 1 - 3. The target wake time field of the TWT element indicating a given link indicates the start time of the TWP SP for that link. The start time may be indicated with reference to the Time Synchronization Function (TSF) time of the link.

[0062] In example 400, the initial TWT SPs 430 - 1, 430 - 2, and 430 - 3 for Links 1 - 3 may be aligned respectively. The TWT wake time intervals associated with the TWT protocols for Links 1 - 3 may be set differently. Thus, the second TWT SPs 431 - 1, 431 - 2, and 431 - 3 for Links 1 - 3 may not be aligned respectively. STA 421, STA 422, and STA 423 may enter a doze state respectively between the end of the initial TWT SPs 430 - 1, 430 - 2, and 430 - 3 and the start of the second TWT SPs 431 - 1, 431 - 2, 431 - 3.

[0063] Figure 5Shows an example Target Wake Time (TWT) element 500 that can be used to support individual TWT operations.

[0064] In an example, an AP and a STA can use the TWT element 500 to negotiate a TWT protocol. The AP and / or the STA can transmit the TWT element 500 in a separately addressed management frame. For example, the management frame can be of the following types: action, action no ack, (re)association request / response, and probe request / response.

[0065] The TWT schedule and parameters can be provided during the TWT setup phase. Re - negotiation / change of the TWT schedule can be signaled via a separately addressed frame containing the updated TWT schedule / parameters. The frame can be a management frame as described above or a control or data frame carrying a field containing the updated TWT schedule / parameters.

[0066] Reference Figure 5 , the TWT element 500 includes an element ID field, a length field, a control field, and a TWT parameter information field.

[0067] The element ID field (e.g., 1 octet in length) can indicate that the information element 500 is a TWT element. The length field (e.g., 1 octet) can indicate the length of the TWT element 500 from the control field until the end of the TWT element 500. The end of the TWT element 500 can be the end of the TWT channel field or the end of the link ID bitmap field in the TWT parameter information field.

[0068] The TWT parameter information field can contain a request type field (e.g., 2 octets), a target wake time field (e.g., 8 octets or less), a TWT group assignment field (e.g., 9, 3, 2, or 0 octets), a nominal minimum TWT wake duration field (e.g., 1 octet), a TWT wake time interval mantissa (e.g., 2 octets), a TWT channel field (e.g., 1 octet), an optional NDP paging field (e.g., 0 or 4 octets), and / or a link ID bitmap field (e.g., 0 or 2 octets).

[0069] The request type field can indicate the type of the TWT request. The request type field can contain a TWT request field (e.g., 1 bit), a TWT setup command field (e.g., 3 bits), a trigger field (e.g., 1 bit), an implicit field (e.g., 1 bit), a flow type (e.g., 1 bit), a TWT flow identifier (e.g., 3 bits), a TWT wake time interval exponent (e.g., 5 bits), and / or a TWT protection field (e.g., 1 bit).

[0070] The TWT request field may indicate whether the TWT element 500 represents a request. If the value of the TWT request field is 1, the TWT element 500 may represent a request for initiating TWT scheduling / setup.

[0071] The TWT setup command field may indicate the type of the TWT command. In a TWT request, the type of the indicated TWT command may be: Request TWT (the TWT response STA specifies the TWT value; for example, the field is set to 0), Suggest TWT (the TWT request STA suggests the TWT value; for example, the field is set to 1), and Require TWT (the TWT request STA requires the TWT value; for example, the field is set to 2).

[0072] In a TWT response, the type of the indicated TWT command may be: TWT Group (the TWT response STA suggests a TWT group parameter with TWT parameters different from those suggested or required by the TWT request STA; for example, the field is set to 3), Accept TWT (the TWT response STA accepts the TWT request with the TWT parameters indicated by the TWT request STA; for example, the field is set to 4), Alternative TWT (the TWT response STA suggests TWT parameters different from those suggested or required by the TWT request STA; for example, the field is set to 5), Indicate TWT (the TWT response STA requires TWT parameters different from those suggested or required by the TWT request STA; for example, the field is set to 6), or Reject TWT (the TWT response STA rejects the TWT setup; for example, the field is set to 7).

[0073] In a TWT response, the TWT command may also indicate an unsolicited response or a broadcast TWT. An unsolicited TWT response is a unicast frame intended for a specific STA. An unsolicited TWT response may be followed by an acknowledgment frame from the STA that receives the unsolicited TWT response. A broadcast TWT may be intended for multiple STAs and may be carried in a broadcast frame (e.g., a beacon frame). A broadcast TWT cannot be acknowledged by the receiving STA.

[0074] The TWT response STA may use an unsolicited TWT response to require the recipient to follow the TWT schedule included in the TWT element. In an embodiment, the unsolicited TWT response may have the TWT request field set to 0 and the value of 'Indicate TWT' in the TWT setup command field. The TWT response STA may use a broadcast TWT response to schedule TWT for any STA that receives and decodes the TWT element.

[0075] In some embodiments, a TWT element (such as TWT element 500) may contain a set of TWT parameters for multiple TWT negotiations or indications as described herein. Thus, a TWT element may include multiple instances of control and TWT parameter information fields. The TWT flow identifier of the request type field indicates which parameters' TWT negotiation the TWT parameter information field carries.

[0076] Figure 6 An example TWT element 600 that can be used to support restricted target wake time (r-TWT) operations is shown. For r-TWT, the TWT element 600 may be transmitted in a broadcast management frame, which may be a beacon frame, a TIM broadcast frame, a probe response frame, etc. In this embodiment, the TWT element 600 provides a non-negotiated TWT schedule (e.g., a broadcast TWT schedule).

[0077] As shown, the TWT element 600 includes an element ID field, a length field, a control field, and a TWT parameter information field.

[0078] The element ID field (e.g., 1 octet in length) may indicate that the information element 600 is a TWT element. The length field (e.g., 1 octet) may indicate the length of the TWT element 600 from the control field until the end of the TWT element 600. The end of the TWT element 600 may be the end of the broadcast TWT information field or the end of the r-TWT traffic information field of the TWT parameter information field.

[0079] The TWT parameter information field may include a request type field, a target wake time field (e.g., 2 octets), a nominal minimum TWT wake duration field (e.g., 1 octet), a TWT wake time interval mantissa (e.g., 2 octets), a broadcast TWT information field (e.g., 2 octets), and an optional r-TWT traffic information field (e.g., 0 or 3 octets).

[0080] The request type field may include a TWT request field, a flow type field, a TWT wake time interval exponent field, and other fields.

[0081] The TWT request field indicates whether the TWT element 600 is a request. If the value of the TWT request field is 0, the TWT element 600 may represent a response to a request for initiating TWT scheduling / setup (claiming TWT), a non-claiming TWT response, and / or a broadcast TWT message.

[0082] The TWT wake-up time interval represents the average time that a TWT-requesting STA or a TWT-scheduled STA is expected to elapse between consecutive TWTSP start times in the TWT schedule. The TWT wake-up time interval exponent field indicates the (base 2) exponent used to calculate the TWT wake-up time interval in microseconds. In an embodiment, the TWT wake-up time interval is equal to: (TWT wake-up time interval mantissa) × 2 (TWT唤醒时间间隔指数) . The TWT wake-up time interval mantissa value is expressed in microseconds and is represented in base 2 in the TWT wake-up time interval mantissa field of the TWT parameter information field.

[0083] The nominal minimum TWT wake-up duration field may indicate the minimum amount of time (in units indicated by the wake-up duration unit subfield of the control field) that a TWT-requesting STA or a TWT-scheduled STA is expected to wake up within a cycle of the TWT wake-up time interval to complete a frame exchange.

[0084] In a TWT response that successfully establishes a TWT protocol between a TWT-requesting STA and a TWT-responsive STA, the flow type field may indicate the type of interaction between the TWT-requesting STA and the TWT-responsive STA within the TWT SP of the TWT protocol. A flow type field equal to 0 may indicate an announced TWT. In an announced TWT, the TWT-responsive STA may not transmit a frame to the TWT-requesting STA within the TWT SP until it receives a PS-Poll frame or a QoS null frame from the TWT-requesting STA. A flow type field equal to 1 may indicate an unannounced TWT. In an unannounced TWT, the TWT-responsive STA may transmit a frame to the TWT-requesting STA within the TWT SP before receiving a frame from the TWT-requesting STA.

[0085] Within a TWT element with a TWT setup command value of 'Request TWT', 'Suggest TWT', or 'Demand TWT', the broadcast TWT ID may indicate the specific broadcast TWT that the TWT-requesting STA requests to participate in. Within a TWT element with a TWT setup command value of 'Accept TWT', 'Replace TWT', 'Indicate TWT', or 'Reject TWT', the broadcast TWT ID may indicate the specific broadcast TWT for which the TWT-responsive STA provides TWT parameters. A value of 0 in the broadcast TWT ID subfield may indicate a broadcast TWT whose members correspond to all STAs that are members of the BSS corresponding to the BSSID of the management frame carrying the TWT element and are allowed to contain trigger frames with random access resource units for unassociated STAs. The broadcast TWT ID subfield in the r-TWT parameter set field is always set to a non-zero value.

[0086] The broadcast TWT element 600 containing the r-TWT parameter set is also referred to as the r-TWT element. There is a subfield in the r-TWT traffic information of the broadcast TWT information field that can be set to 1 to indicate the presence of the r-TWT traffic information field in the TWT element 600. When the r-TWT traffic information presence subfield is set to 1, the r-TWT traffic information field exists in the r-TWT parameter set field.

[0087] The r-TWT traffic information field can include a traffic information control field, an r-TWT DL TID bitmap field, and an r-TWT UL TID bitmap field.

[0088] The traffic information control field can include a DL TID bitmap valid subfield and a UL TID bitmap valid subfield. The DL TID bitmap valid subfield indicates whether the r-TWT DL TID bitmap field has valid information. When the value of the DL TID bitmap valid subfield is set to 0, it can indicate that the DL traffic of the TID is recognized as delay-sensitive traffic and the r-TWT DL TID bitmap field is reserved. The UL TID bitmap valid subfield can indicate whether the r-TWT UL TID bitmap field has valid information. When the value of the UL TID bitmap valid subfield is set to 0, it can indicate that the UL traffic of the TID is recognized as delay-sensitive traffic and the r-TWT UL TID bitmap field is reserved.

[0089] The r-TWT DL TID bitmap subfield and the r-TWT UL TID bitmap subfield can respectively specify which TIDs are identified as delay-sensitive traffic flows in the downlink and uplink directions by the TWT-scheduling AP or the STA scheduled by the TWT. A value of 1 at bit position k in the bitmap indicates that TID k is classified as a delay-sensitive traffic flow. A value of 0 at bit position k in the bitmap indicates that TID k is not classified as a delay-sensitive traffic flow.

[0090] A separate Target Wake Time (TWT) can be a specific time or set of times negotiated between two separate stations (e.g., an STA and another STA, or an STA and an AP, etc.), at which the stations can wake up during the service period (SP) of the TWT to exchange frames.

[0091] In trigger-enabled TWT, the AP can use uplink OFDMA (Orthogonal Frequency Division Multiple Access) and / or uplink MU-MIMO (Multi-User Multiple Input Multiple Output) during the trigger-enabled TWT SP to transmit trigger frames for scheduling uplink multi-user transmissions from one or more STAs. The TWT STA that receives the trigger frame from the AP can transmit frames to the AP via the resources indicated in the trigger frame during the trigger-enabled TWT SP.

[0092] In a non-trigger-enabled TWT, it may not be necessary for the AP to transmit a trigger frame to schedule an uplink multi-user transmission from one or more STAs during a non-trigger-enabled TWT SP.

[0093] In a declared TWT, a STA may transmit a frame (e.g., a PS-Poll frame or a QoS Null frame) to the AP to retrieve downlink buffered data from the AP during the TWT SP. In an undeclared TWT, the AP may transmit downlink data to the TWT STA without receiving a frame (e.g., a PS-Poll frame or a QoS Null frame) from the TWT STA during the TWT SP.

[0094] Figure 7 An example 700 of a stand-alone TWT operation is shown. As Figure 7 shown, example 700 includes an AP 710, a STA 711, and a STA 712. In the example, the AP 710 may be a TWT response STA, and the STAs 711 and 712 may be TWT request STAs.

[0095] In the example, the STA 711 may transmit a TWT request to the AP 710 to set up a first trigger-enabled TWT protocol. The STA 711 may set the trigger field of the TWT request to 1 to indicate that it is requesting a trigger-enabled TWT. The AP 710 may accept the first TWT protocol with the STA 711. The AP 710 may confirm the acceptance in the TWT response sent to the STA 711. The TWT response may indicate the next TWT 730, which indicates the time until the next TWT SP 720 according to the first TWT protocol.

[0096] In the example, the AP 710 may transmit an unsolicited TWT response to the STA 712 to set up a second trigger-enabled TWT protocol with the STA 712 without receiving a TWT request from the STA 712. The first and second TWT protocols may be set as declared TWTs.

[0097] After setting up the TWT protocol, STA 711 and STA 712 can enter the doze state until the TWT SP 720 starts. During the period when the trigger enables the TWT SP 720, the AP 710 can transmit trigger frames. STA 711 and STA 12 can respond to the trigger frames by indicating that they are in the awake state. In an example, STA 711 can transmit a Power-Saving Poll (PS-Poll) frame. The PS-Poll frame can include a BSSID (Receiver Address: RA) field set to the address of the AP 710 and a Transmitter Address (TA) field set to the address of the STA 711. In an example, STA 712 can transmit a QoS Null frame in response to the trigger frame. The QoS Null frame can include a MAC header without a frame body (e.g., Frame Control field, Duration field, Address fields, Sequence Control field, QoS Control field).

[0098] In response to the PS-Poll frame and the QoS Null frame, the AP 710 can transmit a Multi-STA Block Acknowledgment (M-BA) frame. The M-BA frame can contain acknowledgment information associated with the PS-Poll frame and the QoS Null frame received from the STA 711 and 712 respectively. Subsequently, STA 711 and STA 712 can receive a Downlink Bufferable Unit (DL BU) from the AP 710. The DL BU can contain Media Access Control (MAC) Service Data Units (MSDUs), Aggregate MAC Service Data Units (A-MSDUs), and / or Bufferable MAC Management Protocol Data Units (MMPDUs). STA 711 and STA 712 can transmit Block Acknowledgment (BA) frames in response to the DL BU. At the end of the TWT SP 720, STA 711 and STA 712 can return to the doze state.

[0099] The STA can perform a separate TWT setup exchange. The STA may not transmit frames to an AP outside the negotiated TWT SP. The STA may not transmit frames that are not included in a High-Efficiency Trigger-Based Physical Protocol Data Unit (HE TB PPDU) to an AP within the trigger-enabled TWT SP. The HE TB PPDU can be transmitted by the STA based on a trigger frame received that triggers an uplink multi-user transmission.

[0100] A trigger-enabled TWT protocol AP can schedule trigger frames for a STA to transmit within a trigger-enabled TWT SP. The STA can transmit a HE TB PPDU in response to the trigger frame sent during the trigger-enabled TWT SP. If the TWT is a declared TWT, a STA in power save (PS) mode can include a PS-Poll frame or a QoS Null frame in the HE TB PPDU to indicate to the AP that the STA is currently awake. The AP that receives a PS-Poll frame or a QoS Null frame or any other indication from a STA in PS mode can deliver as many buffered BUs as are available at the AP to the STA during the TWT SP.

[0101] A broadcast target wake time (TWT) can be a specific time or set of times broadcast by an AP to one or more STAs at which the STAs can wake up during the SP of the TWT to exchange frames with the AP.

[0102] Figure 8 An example 800 of broadcast TWT operation is shown. As Figure 8 shown, example 800 includes an AP 810, a STA 811, and a STA 812. In example 800, the AP 810 can be a TWT scheduling AP, and the STAs 811 and 812 can be TWT-scheduled STAs.

[0103] In the example, the AP 810 can include a broadcast TWT element indicating a broadcast TWT SP 820 in a beacon frame. During the broadcast TWT SP 820, the AP 810 can transmit a trigger frame or a DL BU to the STAs 811 and 812. The AP 810 can send beacon frames at regular time intervals defined as the target beacon transmission time (TBTT). The TBTT is a time interval measured in time units (TUs). A TU is equal to 1024 microseconds.

[0104] In the example, the STAs 811 and 812 can enter a doze state until the first target beacon transmission time (TBTT). The STAs 811 and 812 can wake up to receive the beacon frame at the first TBTT to determine the broadcast TWT. After receiving the broadcast TWT element in the beacon frame, the STAs 811 and 812 can re-enter the doze state until the trigger-enabled TWT SP 820 begins.

[0105] During the period when the trigger enables TWT SP 820, the AP 810 can transmit a basic trigger frame to the STAs 811 and 812. The STA 811 can indicate that it is awake by transmitting a PS-Poll, and the STA 812 can indicate that it is awake by transmitting a QoS null frame in response to the basic trigger frame. Subsequently, the STAs 811 and 812 can receive DLBUs from the AP 810. The STAs 811 and 812 can return to the doze state outside of TWT SP 720.

[0106] In an example, a STA that is intended to operate in a power saving mode can negotiate a wake-up TBTT and a wake-up time interval with the AP. For example, as Figure 8 shown, the STA 811 can transmit a TWT request to the AP 810 that identifies the wake-up time interval between the wake-up TBTT of the first beacon frame and subsequent beacon frames. The AP 810 can respond to the TWT request that confirms the wake-up TBTT and the wake-up time interval with a TWT response. After successfully completing the negotiation, the STA 811 can enter the doze state until the first negotiated wake-up TBTT 830. The STA 811 can be in the awake state to listen for the beacon frame transmitted at the first negotiated wake-up TBTT 830. If the STA 811 receives a beacon frame from the AP 810 at or after the TBTT 830, the STA 811 can return to the doze state until the next wake-up TBTT unless the traffic indication map (TIM) element in the beacon frame contains a positive indication for the STA 811. After the nominal minimum TBTT wake-up duration has passed since the start time of the TBTT, the STA 811 can return to the doze state.

[0107] A network allocation vector (NAV) is an indicator of a time period maintained by a station (STA) during which the STA cannot initiate a transmission on the wireless medium (WM) regardless of whether the STA's clear channel assessment (CCA) function senses that the WM is busy. A STA that receives at least one valid frame in a PSDU can update its NAV with information from any valid duration field in the PSDU. When the value of the received duration field is greater than the STA's current NAV value, the STA can update the NAV.

[0108] TWT protection is a mechanism used to protect TWT sessions from external STA transmissions. During a TWT SP configured to protect a TWT session, a STA initiating a transmission opportunity (TXOP) of a transmission frame can transmit a Request to Send (RTS) frame or a Clear to Send (CTS) frame to protect the TWT session by setting the NAV of other STAs based on receiving an RTS frame and / or a CTS frame. The RTS frame can include a Frame Control field, a Duration field, a Receiver Address (RA) field, a Transmitter Address (TA) field, and a Frame Check Sequence (FCS) field. The CTS frame can include a Frame Control field, a Duration field, a Receiver Address (RA) field, and a Frame Check Sequence (FCS) field.

[0109] The TWT protection field in the TWT element can indicate whether the TWT is protected or unprotected. The TWT requesting STA can set the TWT protection field to 1 to request the TWT responding STA to provide protection for the TWT SP set. A TWT protection field equal to 1 can indicate using the NAV protection mechanism to protect access to the medium during the corresponding TWT SP.

[0110] Figure 9 An example 900 of TWT protection in a standalone TWT operation is shown. As Figure 9 shown, example 900 includes an AP 910 and a STA 911.

[0111] In the example, the AP 910 can set the TWT protection field to 1 in the TWT response frame to protect the TWT SP using the NAV protection mechanism. After receiving the TWT response frame, the STA 911 can enter the doze state until the next TWT 930. The AP 910 that has set the TWT protection field to 1 can transmit a NAV setting frame at the start of the TWT SP 920. For example, the NAV setting frame can be an RTS frame or a CTS frame.

[0112] A STA that receives the NV setting frame and is not scheduled to access the medium during the TWT SP 920 can set its NAV according to the NAV setting frame. In the NAV setting frame, the STA may not access the medium for a specified amount of time.

[0113] The STA 911 can be scheduled to access the medium during the TWT SP 920. The STA 911 can respond to the RTS frame with a CTS frame. After receiving the CTS frame, the AP 910 can transmit a downlink frame to the STA 911. The STA 911 can respond to the downlink frame with a BA frame. When the TWT SP 920 ends, the STA 911 can return to the doze state.

[0114] Traffic from many real-time applications has strict latency requirements (e.g., very low average latency, worst-case latency of about a few milliseconds to tens of milliseconds, and small jitter, all of which may also have certain reliability constraints). Such traffic is referred to as latency-sensitive traffic. Constrained TWT operation can allow an AP to use enhanced medium access protection and resource reservation mechanisms to provide more predictable latency, reduced worst-case latency, and / or reduced jitter with higher reliability for latency-sensitive traffic.

[0115] Using TWT, a STA can negotiate wake-up periods with an AP to transmit and receive data packets. When the STA remains in the doze state, the STA can save power for the rest of the time. TWT operation can reduce the power consumption of participating STAs. When STAs are distributed across different TWT sessions, TWT can also reduce the level of contention and can support collision-free and deterministic operation.

[0116] Using constrained TWT (r-TWT) operation, an AP can allocate r-TWT service periods, which can be used to transmit data frames with latency-sensitive traffic by the AP and one or more STAs. r-TWT traffic information can be used to identify data frames with latency-sensitive traffic, and the traffic information can be provided using traffic identifier (TID) bitmaps of uplink and downlink traffic flows included in broadcast frames (e.g., beacon frames, probe response frames, etc.) sent by the AP. Data frames with TIDs not identified as latency-sensitive traffic may not be transmitted during the r-TWT SP.

[0117] The constrained TWT scheduling AP, referred to as the r-TWT scheduling AP, is an extremely high throughput AP (EHT AP) that supports constrained TWT operation. The constrained TWT scheduled STA, referred to as the r-TWT scheduling STA, is a non-AP EHT STA that supports constrained TWT operation. When the constrained TWT protocol is set, the EHT AP can announce the constrained TWT service period (r-TWT SP) scheduling information in the broadcast TWT element. The broadcast TWT element can be included in management frames such as beacon frames or probe response frames. The EHT AP can schedule silent time intervals that overlap with the r-TWT SP. The duration of the service time interval within the r-TWT SP that overlaps with the silent time interval can be 1 TU. The service time interval can start at the same time as the corresponding r-TWT SP. The overlapping silent time intervals can be scheduled by including one or more silent elements in the beacon frame and / or probe response frame so that traditional STAs do not initiate frame transmissions during the silent time intervals that overlap with the r-TWT SP.

[0118] Figure 10 An example 1000 of r-TWT operation is shown. As Figure 10As shown, Example 1000 includes AP 1010, STA 1011, and STA 1012. AP 1010 can be an r-TWT scheduling AP. STA 1011 can be an r-TWT scheduled STA. STA 1012 can be a legacy STA or an EHT STA that is not scheduled by AP 1010 during the r-TWT SP.

[0119] As Figure 10 shown, AP 1010 can transmit a beacon frame that includes a TWT element and a silent element. The TWT element can indicate the r-TWT SP 1020 and the TIDs allowed to be transmitted during the r-TWT SP 1020. The silent element can indicate the silent time interval 1021. AP 1010 can be intended to transmit delay-sensitive DL BUs to STA 1011 during the r-TWT SP 1020.

[0120] STA 1011 can enter the doze state after receiving the beacon frame from AP 1010. STA 1011 can remain in the doze state until the r-TWT SP 1020 starts. STA 1012 can receive the beacon frame and can transmit a data frame with a TID different from the TID indicated in the TWT element of the beacon frame before the r-TWT SP 1020 starts. STA 1012 can end its frame transmission before the r-TWT SP 1020 starts.

[0121] During the r-TWT SP 1020, AP 1010 and STA 1011 can exchange RTS frames and CTS frames, and then transmit a data frame from AP 1010 to STA 1011. The data frame can include the TID in the TIDs allowed to be transmitted during the r-TWT SP 1020. STA 1011 can confirm the data frame from AP 1010 by transmitting a block acknowledgment (BA) frame. STA 1011 can return to the doze state at the end of the r-TWT SP 1020.

[0122] STA 1012 can avoid using EDCA to access the channel at least during the silent time interval 1021 indicated in the beacon frame. When the silent time interval ends or when the r-TWT SP 1020 ends, STA 1012 can resume its frame transmission.

[0123] Figure 11Shows an example silent element 1100 that can be used to support silent interval operations. In an example embodiment, to enable one or more silent intervals, the AP can announce / transmit / broadcast a frame containing a silent element (such as silent element 1100) to one or more STAs. The silent element can include information for scheduling one or more silent intervals. In an example embodiment, a silent interval is a time interval during which no transmission / communication occurs on the wireless medium between the AP and one or more non-AP STAs configured with a silent interval. The silent element can be transmitted in a broadcast management frame, such as a beacon frame, a TIM broadcast frame, a probe response frame, etc.

[0124] As Figure 11 shown, the silent element 1100 can include an element ID field, a length field, a silent count field (e.g., 1 octet), a silent period field (e.g., 1 octet), a silent duration field (e.g., 2 octets), and a silent offset field (e.g., 2 octets). The STA and / or the AP can determine the start time of the silent interval indicated in the silent element 1100 based on one or more parameters in the silent element 1100. The STA and / or the AP can determine the time offset between the frame indicating the silent element 1100 and the start time of the silent interval based on one or more parameters in the silent element 1100.

[0125] In an embodiment, the silent count field can be set to the number of TBTTs of beacon intervals until the start of the silent interval. The value 0 can be reserved.

[0126] In an embodiment, the silent period field can be set to the number of beacon intervals between the start times of periodically scheduled silent intervals indicated by the silent element 1100. A silent period field set to 0 can indicate an undefined periodic silent interval.

[0127] In an embodiment, the silent duration field can be set to the duration of the silent interval scheduled by the silent element 1110. The silent interval duration can be represented in TUs.

[0128] In an embodiment, the silent offset field can indicate the offset of the start of the silent interval scheduled by the silent element 1100 from the TBTT specified by the silent count field. The offset can be represented in TUs. The value of the silent offset field can be less than one beacon interval.

[0129] Figure 12 Shows an instance 1200 of silent interval operation. As Figure 12As shown, example 1200 includes an AP 1210 and a STA 1211. The AP 1210 can transmit beacon frames containing a silent element to indicate a silent time interval. The silent element can include a silent count field, a silent offset field, a silent duration field, and / or a silent period field. In the example, the silent count field can be set to 1, indicating that the silent time interval starts in a beacon time interval outside of 1 TBTT. The silent offset field indicates the offset of the start of the silent time interval from the TBTT indicated in the silent count field (e.g., from the start of the beacon frame on the TBTT).

[0130] The STA 1211 can receive beacon frames containing a silent element. After receiving the beacon frame, the STA 1211 can obtain and / or store information about the silent time interval indicated by the silent element. The STA 1211 can use the silent count field and the silent offset field of the silent element to determine the start time of the silent time interval. The STA 1211 can use the silent duration field of the silent element to determine the length of the silent time interval.

[0131] The STA 1211 can use the information about the silent time interval to adjust its communication behavior on the wireless medium. In the example, the STA 1211 can transmit a data frame to the AP 1210 before the start of the silent time interval. The STA 1211 can stop transmitting data frames before the start of the silent time interval. The STA 1211 can set its Network Allocation Vector (NAV) based on the length of the silent time interval at the start of the silent time interval. Thus, the STA 1211 can refrain from transmitting or communicating with the AP 1210 during the silent time interval. In an embodiment, the STA 1211 can start a timer with a value of the NAV set based on the length of the silent time interval. When the timer is running, the STA 1211 can stop uplink frame transmission and / or downlink frame reception. When the timer expires, the STA 1211 can resume uplink frame transmission and / or downlink frame reception. The STA 1211 can transmit an uplink frame based on the data in the uplink buffer.

[0132] Figure 13 Example 1300 showing rescheduling or stopping the scheduling of a silent time interval is presented. As Figure 13 shown, the AP 1310 can transmit a beacon frame that contains a silent element indicating a first silent time interval (QI 1) and a second silent time interval (QI 2). In the example, QI 2 can be scheduled after QI 1.

[0133] In an example, the AP 1310 may stop scheduling a silent time interval or may transmit a silent element that has changed in terms of a silent period, a silent duration, and / or a silent offset of a scheduled silent time interval. In an example, the most recently transmitted / received beacon frame or probe response frame may be used to determine a subsequent silent time interval. In an example embodiment, scheduling of a silent time interval based on an older beacon frame or probe response frame may be discarded.

[0134] In example 1300, the AP 1310 may transmit a probe response frame that includes a silent element indicating a third silent time interval (QI 3) after a first silent time interval (QI 1) and before a start of a second silent time interval (QI 2). In an example, based on the probe response frame indicating QI 3, the second silent time interval (QI 2) may be discarded and the silent time interval (QI 3) may be scheduled. In an example, during the first silent time interval (QI 1) and / or the third silent time interval (QI 3), no transmission or communication may occur between the AP 1310 and a STA configured with a silent time interval.

[0135] In the prior art, an AP may transmit a beacon frame or a probe response frame to stop scheduling a silent time interval or to reschedule a silent time interval. The beacon frame or the probe response frame may include a silent element indicating one or more silent time intervals (e.g., outside of a scheduled silent time interval). A STA configured with a silent time interval may not transmit or receive a frame during the silent time interval. Configuration of the silent time interval may reduce battery power consumption and interference. In an example implementation, when some other STAs are configured with r-TWT SP, configuration of the silent time interval may prevent one or more STAs from accessing the channel. This may reduce packet transmission latency for the STAs configured with r-TWT SP. In some example scenarios, configuring the silent time interval may increase packet transmission latency and may reduce the quality of service (QoS) and throughput of a STA configured with a silent time interval.

[0136] In the prior art, an AP can transmit a beacon frame or a probe response frame indicating an r-TWT SP. The AP can also transmit a beacon frame indicating a silent time interval. The silent time interval can overlap with the r-TWT SP. Subsequently, the AP can transmit a frame indicating the termination of the r-TWT SP during the silent time interval. In an example implementation, a first STA that supports r-TWT operation and receives a frame indicating the termination of the r-TWT SP can terminate the r-TWT SP. Thus, after receiving a frame indicating the termination of the r-TWT SP, the first STA can access the channel (e.g., using EDCA). A second STA that does not support r-TWT operation and receives a frame indicating the termination of the r-TWT SP may not terminate the r-TWT SP. Thus, the second STA can continue to defer channel access based on the silent time interval. Thus, although the r-TWT SP is terminated, the first STA that supports r-TWT operation can access the channel earlier than the second STA that does not support r-TWT operation. This results in an access fairness issue between STAs.

[0137] The embodiments solve this problem by providing a mechanism for STAs configured with a silent time interval to terminate the silent time interval before its end time. In an embodiment, the AP can transmit a first frame indicating one or more silent time intervals of one or more STAs. The AP can transmit a second frame indicating the termination of the silent time interval during the silent time interval among the one or more silent time intervals. The silent time interval can terminate before the configured duration of the silent time interval. This improves packet transmission, QoS, and throughput for STAs configured with a silent time interval. It also improves channel access fairness between STAs that support r-TWT operation and STAs that do not support r-TWT operation.

[0138] In an example embodiment, the AP can transmit a beacon frame or a probe response frame indicating the r-TWT SP of a second STA. The transmission of the second frame (indicating the termination of the silent time interval) can be in response to determining that the wireless medium is not being used by the second STA configured with the r-TWT SP and that the silent time interval overlaps with the r-TWT SP. In an example embodiment, the transmission of the second frame can be in response to determining that the silent time interval overlaps with the r-TWT SP and that the r-TWT SP has terminated.

[0139] In an example embodiment, the AP can transmit a first frame indicating one or more silent time intervals to one or more STAs. The AP can transmit a second frame indicating the termination of the silent time interval among the one or more silent time intervals to one or more STAs. The transmission of the second frame occurs during the silent time interval.

[0140] In an example embodiment, a STA may receive a first frame indicating one or more silent time intervals. The STA may receive a second frame indicating the termination of a silent time interval among the one or more silent time intervals during the silent time interval. The STA may terminate the silent time interval in response to the second frame received during the silent time interval.

[0141] In an example, the first frame may be a beacon frame or a probe response frame. In an example, the first frame may be a broadcast frame.

[0142] In an example embodiment, the first frame may include one or more silent elements of one or more silent time intervals.

[0143] In an example embodiment, the silent element may include the following fields:

[0144] - A silent count field indicating the number of TBTTs of beacon time intervals until the start of the silent time interval;

[0145] - A silent period field indicating the number of beacon time intervals between the start times of the silent time intervals of a periodic schedule defined by the silent element;

[0146] - A silent duration field indicating the duration of the silent time interval; and / or

[0147] - A silent offset field indicating the offset of the start time of the silent time interval from the TBTT specified by the silent count field.

[0148] In an example embodiment, the silent time interval is a time interval during which transmission and / or communication may not occur on the wireless medium between an AP and one or more STAs configured with the silent time interval. The STA may determine the silent time interval configuration parameters based on one or more fields of the silent element.

[0149] In an example embodiment, the AP may further transmit a fourth frame to a second STA configured with an r-TWT SP during a silent time interval overlapping with the r-TWT SP. The fourth frame may indicate the termination of the r-TWT SP.

[0150] In an example embodiment, the second frame may be a broadcast frame. In an example embodiment, the second frame may be at least one of a probe response frame, a control frame, a CF end frame, a QoS data frame, a QoS null frame, a TIM broadcast frame, and / or a beacon frame.

[0151] In an example embodiment, in the case where the second frame is a QoS null frame or a QoS data frame, the QoS null frame or the QoS data frame includes an aggregation control (A control) field indicating the termination of the current silent time interval.

[0152] In an example embodiment, when the second frame is a control frame, the control frame includes a field indicating the termination of the silent time interval.

[0153] In an example embodiment, when the second frame is a probe response frame, the probe response frame may include one or more silent elements of one or more silent time intervals. The STA may determine the silent time interval configuration parameters based on one or more fields of the silent elements in the probe response frame. The STA may determine the termination of the current silent time interval based on one or more silent elements in the received probe response frame. The one or more silent elements may include at least one of the following:

[0154] - A silent count field indicating the number of TBTTs of beacon time intervals until the start of the next silent time interval;

[0155] - A silent period field indicating the number of beacon time intervals between the start times of the silent time intervals of the periodic schedule defined by the silent element;

[0156] - A silent duration field indicating the duration of the silent time interval; and / or

[0157] - A silent offset field indicating the offset of the start time of the silent time interval from the TBTT specified by the silent count field.

[0158] In an example embodiment, when the second frame is a CF end frame, the CF end frame may include at least one of the following fields:

[0159] - A frame control field containing sub-fields for controlling the CF end frame, where at least one of the sub-fields indicates that the frame type of the second frame is a CF end frame;

[0160] - A duration field indicating the estimated time required for the transmission frame plus the applicable IFS, where the duration field is set to 0 when transmitted by a non-directional multi-gigabit (non-DMG) STA;

[0161] - A receiver address (RA) field indicating the MAC address of the STA that receives the CF end frame, where the receiver address is a broadcast address when transmitted by a non-directional multi-gigabit (non-DMG) STA; and / or

[0162] - A BSSID / transmitter address (TA) field indicating the MAC address of the STA that transmits the CF end frame, where the transmitter address is the address of the STA included in the AP when transmitted by a non-directional multi-gigabit (non-DMG) STA.

[0163] In an example embodiment, the AP may transmit and / or receive a third frame to / from a STA configured with a silent time interval after transmitting the second frame during the silent time interval. After receiving the second frame during the silent time interval, the STA may further transmit the third frame to the AP using EDCA channel access. In an example embodiment, the AP may further transmit and / or receive additional frames to / from one or more STAs configured with a silent time interval based on the termination of the silent time interval.

[0164] In an example embodiment, one or more STAs configured with a silent time interval may further transmit and / or receive additional frames to / from the AP using EDCA channel access based on the termination of the silent time interval. In an example embodiment, the additional frame may be at least one of a data frame, a control frame, and a management frame.

[0165] In an example embodiment, the AP may transmit a beacon frame or a probe response frame indicating the r-TWT SP of a second STA. The second STA may be a TWT-scheduled STA. The second STA may have a buffered MSDU having a TID indicated as delay-sensitive traffic in the first frame. In an example embodiment, the transmission of the second frame may be in response to determining that the wireless medium is not being used by the second STA configured with the r-TWT SP and that the silent time interval overlaps with the r-TWT SP.

[0166] In an example embodiment, the transmission of the second frame may be in response to determining that the silent time interval overlaps with the r-TWT SP and that the r-TWT SP has terminated.

[0167] In an example embodiment, the AP may determine that the r-TWT SP may terminate in at least one of the following conditions:

[0168] - When the wireless medium is not being used by the second STA configured with the r-TWT SP during the r-TWT SP;

[0169] - When the wireless medium is being used by the second STA configured with the r-TWT SP and / or the use of the wireless medium is completed before the r-TWT SP;

[0170] - When the wireless medium may be used by the second STA configured with the r-TWT SP and / or the use of the wireless medium is completed before the silent time interval.

[0171] In an example embodiment, the AP may determine that the wireless medium is not being used by the second STA configured with the r-TWT SP during the r-TWT SP in at least one of the following scenarios:

[0172] - When the AP does not receive a response frame from the second STA in response to a request frame transmitted during the r-TWT SP. In an example embodiment, the request frame can be at least one of a trigger frame, a data frame, and / or a QoS data frame. In an example embodiment, the trigger frame can be at least one of a buffer status report poll (BSRP) trigger frame, a null data packet (NDP) feedback report poll (NFRP) trigger frame, a multi-user request to send (MU-RTS) trigger frame, a basic trigger frame, and a new type of trigger frame. In an example embodiment, the response frame can be at least one of a QoS null frame, a null data packet (NDP) frame, a clear to send (CTS) frame, a power save poll (PS-Poll) frame, an acknowledgment frame, a block acknowledgment frame, a multi-TID block acknowledgment frame, and / or a multi-STA block acknowledgment frame.

[0173] - When the AP does not receive a specific frame during a first time period within the r-TWT SP. In an example embodiment, the specific frame can be an MSDU having a TID indicated as delay-sensitive traffic in a first frame, a request to send (RTS) frame, a power save poll (PS-Poll) frame, or a QoS null frame. In an embodiment, a STA that has not obtained information about the r-TWT SP and the TID indicated in the first frame may not access the wireless medium during the first time period. The AP can determine that the wireless medium is not in use based on not receiving a frame from the STA during the first time period.

[0174] Example embodiments improve channel access fairness between a STA that supports r-TWT operation and a STA that does not support r-TWT operation and is configured with a silent time interval.

[0175] In an example embodiment, based on the AP determining the termination of the r-TWT SP, the AP can transmit a frame indicating the termination of the r-TWT SP. In an example embodiment, the frame can be transmitted during the silent time interval.

[0176] In an example embodiment, the AP can transmit additional frames after transmitting a frame that terminates the r-TWT SP during the silent time interval.

[0177] In an example embodiment, the AP can transmit an additional frame xIFS after transmitting a frame that terminates the r-TWT SP during the silent time interval. In an example embodiment, the AP can transmit an additional frame aggregated with the frame that terminates the r-TWT SP during the silent time interval.

[0178] In an example embodiment, the frame that terminates the r-TWT SP can be one of the following frames:

[0179] - A QoS null frame having an A control field indicating the termination of the r-TWT SP;

[0180] - A QoS data frame having an A control field indicating the termination of the r-TWT SP;

[0181] - A QoS null frame having an EOSP field set to 1;

[0182] - A QoS data frame having an EOSP field set to 1; and

[0183] - A CF end frame.

[0184] In an example embodiment, the xIFS may be SIFS or PIFS.

[0185] In an example embodiment, the STA may be:

[0186] - A STA that does not support r-TWT operation;

[0187] - A STA that is a member of a configured r-TWT;

[0188] - A STA that supports r-TWT operation but is not a member of the configured r-TWT;

[0189] - A STA that is a member of an r-TWT schedule but has no buffered data for one or more TIDs indicated by a frame indicating the r-TWT; or

[0190] - A legacy STA (e.g., a HE STA, a VHT STA, an HT STA, etc.).

[0191] Figure 14 Example 1400 showing the AP terminating the silent time interval is presented. Example 1400 is provided for illustrative purposes only and does not limit the embodiments. As Figure 14 shown, example 1400 includes an AP 1410 and a STA 1411.

[0192] The AP 1410 may transmit a first frame containing a silent element indicating a silent time interval. In an embodiment, the first frame may be a beacon frame or a probe response frame. In an embodiment, the first frame may be a broadcast frame. The STA 1411 may receive the first frame and may configure the silent time interval based on the fields indicated in the silent element. In an embodiment, the STA 1411 may use the silent count field and the silent offset field in the silent element to determine the start time of the silent time interval. In an embodiment, the STA 1411 may use the silent duration field in the silent element to determine the length of the silent time interval. In an embodiment, the STA 1411 may determine that it may not communicate with the AP 1410 during the configured silent time interval. In an embodiment, the STA 1411 may set its NAV to the length of the silent time interval indicated in the silent element.

[0193] In Example 1400, the AP 1410 may wish to terminate the silent time interval before its end time to better utilize resources. In the example, the AP 1410 may have buffered data to send to the STA associated with the AP 1410. As Figure 14 shown, the AP 1410 may transmit a second frame to the STA 1411 during the silent time interval. In an embodiment, the second frame may be a broadcast frame. In an embodiment, the second frame may be a probe response frame, a control frame, a CF-End frame, a QoS data frame, a QoS null frame, a TIM broadcast frame, or a beacon frame.

[0194] In an embodiment, when the second frame is a QoS null frame or a QoS data frame, the QoS null frame or the QoS data frame includes an Aggregate Control (A-Control) field indicating the termination of the silent time interval.

[0195] In an embodiment, when the second frame is a control frame, the control frame includes a field indicating the termination of the silent time interval.

[0196] In an embodiment, when the second frame is a probe response frame, the probe response frame may include one or more silent elements of one or more silent time intervals. The STA 1411 may determine the silent time interval configuration parameters based on one or more fields of the one or more silent elements.

[0197] Returning to Example 1400, the STA 1411 receives the second frame from the AP 1410 during the silent time interval. In an embodiment, the STA 1411 may terminate the silent time interval in response to the received second frame. In an embodiment, the STA 1411 may have buffered data to send to the AP 1410. Thus, the STA 1411 may transmit a third frame to the AP 1410 after the silent time interval terminates. EDCA may be used to transmit the third frame. The third frame may be a data frame, a control frame, or a management frame.

[0198] In an embodiment, when a configured silent time interval begins, STA 1411 and / or AP 1410 stop the transmission / reception of uplink frames and downlink frames. STA 1411 may start a timer with a value of the NAV set based on the length of the silent time interval. While the timer is running, STA 1411 may avoid uplink frame transmission and / or downlink frame reception. STA 1411 may resume uplink frame transmission and / or downlink frame reception in response to the expiration of the timer. STA 1411 may resume / start the uplink transmission of data / control frames in response to the termination of the configured silent time interval. In an embodiment, in response to terminating the silent time interval, STA 1411 may reset the NAV (e.g., set the NAV to zero). Based on terminating the silent time interval, STA 1411 may resume channel access by listening to the wireless medium. In an example, in response to STA 1411 accessing the channel, STA 1411 may transmit an uplink control / data frame to AP 1410 after terminating the silent time interval. In an example, the uplink buffer in STA 1411 may be empty, and STA 1411 may not access the channel even after the termination of the silent time interval.

[0199] By transmitting a second frame indicating the termination of the silent time interval during the silent time interval, AP 1410 and / or STA 1411 may access the channel faster before the end of the silent time interval. Resource utilization is thereby increased.

[0200] Figure 15 Another example 1500 showing the termination of the silent time interval by the AP is presented. Example 1500 is provided for illustrative purposes only and does not limit the embodiments. As Figure 15 shown, example 1500 includes AP 1510 and STAs 1511, 1512, and 1513.

[0201] AP 1510 may transmit a first frame including a silent element indicating the silent time interval. In an embodiment, the first frame may also include a TWT element indicating the r-TWT SP. The TWT element may indicate one or more TIDs of delay-sensitive traffic associated with the r-TWT SP. In example 1500, the silent time interval overlaps with the r-TWT SP.

[0202] In example 500, STA 1511 can be a STA scheduled for TWT in the r-TWT SP. For example, STA 1511 can have buffered uplink data frames with a TID indicated as delay-sensitive traffic in the first frame to be transmitted to AP 1510, or can have buffered downlink data frames with a TID indicated as delay-sensitive traffic in the first frame to be received from AP 1510 during the r-TWT SP. STA 1512 can be a STA not scheduled for TWT in the r-TWT SP. For example, STA 1512 may not have buffered uplink data frames with a TID indicated as delay-sensitive traffic in the first frame to be transmitted to AP 1510, or may not have buffered downlink data frames with a TID indicated as delay-sensitive traffic in the first frame to be received from AP 1510 during the r-TWT SP.

[0203] In example 1500, STA 1511 may not receive the first frame from AP 1510. STA 1512 can receive the first frame from AP 1510. STA 1512 can send a data frame with any TID (e.g., an MDU or A-MSDU with a TID not identified as delay-sensitive traffic in the first frame) to AP 1510. STA 1512 can stop transmitting data frames (with any TID) before the r-TWT SP indicated in the first frame. STA 1512 can defer EDCA channel access for transmitting data frames until the end of the r-TWT SP.

[0204] In an embodiment, AP 1510 can determine that the r-TWT SP can terminate during the r-TWT SP. In an embodiment, based on determining that the r-TWT SP terminates, AP 1510 can transmit a second frame indicating the termination of the silent time interval during the silent time interval. In an embodiment, based on determining that the r-TWT SP terminates, AP 1510 can further transmit a fourth frame indicating the termination of the r-TWT SP during the silent time interval.

[0205] In an embodiment, AP 1510 can determine that the r-TWT SP can terminate under at least one of the following conditions:

[0206] - When the wireless medium may not be used by a STA (e.g., STA 1511) configured with the r-TWT SP during the r-TWT SP;

[0207] - When the wireless medium can be used by a STA (e.g., STA 1511) configured with the r-TWT SP and / or when using the wireless medium is completed before the r-TWT SP;

[0208] -When the wireless medium can be used by a STA (e.g., STA1 1511) configured with r-TWT SP and / or when the use of the wireless medium is completed before the silent time interval.

[0209] In example 1500, the AP 1510 can determine the wireless medium that is not used during the silent time interval.

[0210] In an embodiment, the AP 1510 can determine the wireless medium that is not used during the r-TWT SP. In an embodiment, the AP 1510 can determine that the wireless medium is not used based on not receiving a response frame from the STA 1511 in response to a request frame transmitted during the r-TWT SP. In an embodiment, the AP 1510 can determine that the wireless medium is not used based on not receiving a specific frame (e.g., an MSDU with a TID indicated as delay-sensitive traffic in the first frame, a request to send (RTS) frame, a power save poll (PS-Poll) frame, or a QoS null frame, etc.) during a first time period within the r-TWT SP. In an embodiment, the STA 1511 that has not obtained the information of the r-TWT SP and the TID indicated in the first frame may not access the wireless medium during the first time period. The AP 1510 can determine that the wireless medium is not used when not receiving a specific frame from a TWT-scheduled STA (e.g., STA 1511) during the first time period.

[0211] In an embodiment, based on determining that the wireless medium is not used, the AP 1510 can transmit a fourth frame indicating the termination of the r-TWT SP to the STAs in the BSS belonging to the AP 1510 during the r-TWT SP. In an embodiment, the AP 1510 can also transmit a second frame indicating the termination of the silent time interval during the silent time interval. In an embodiment, the AP 1510 can transmit the second frame after the fourth frame by SIFS. In another embodiment, the AP 1510 can use PIFS instead of SIFS. In a further embodiment, the AP 1510 can use another fixed time value instead of PIFS or SIFS. In an embodiment, the AP 1510 can transmit a PPDU including the second frame and the fourth frame.

[0212] In an example, STA 1512 can be a STA that supports r-TWT operation. In an example, STA 1512 can be scheduled during an r-TWT SP. In an example, STA 1512 may not have data for any TID indicated in the TWT element of the first frame. In an embodiment, after receiving the first frame indicating an r-TWT SP, STA 1512 can configure the r-TWT SP based on the TWT element indicating the r-TWT SP in the first frame. After receiving the fourth frame indicating the termination of the r-TWT SP during the r-TWT SP, STA 1512 can terminate the r-TWT SP.

[0213] In example 1500, STA 1513 can receive a first frame including a silent element indicating a silent time interval and / or a TWT element indicating an r-TWT SP. STA 1513 can be:

[0214] - A STA that does not support r-TWT operation;

[0215] - A STA that is a member of a configured r-TWT;

[0216] - A STA that supports r-TWT operation but is not a member of the configured r-TWT;

[0217] - A STA that is a member of an r-TWT schedule but does not have buffered data for one or more TIDs indicated by the first frame indicating the r-TWT;

[0218] - A legacy STA (e.g., a HE STA, a VHT STA, an HT STA, etc.).

[0219] In example 1500, STA 1513 can configure the silent time interval based on the fields indicated in the silent element included in the first frame. In an embodiment, STA 1513 can determine that STA 1513 does not communicate with AP 1510 during each configured silent time interval. In an embodiment, STA 1513 can set its NAV to the length of the silent time interval indicated in the silent element. In an example, the NAV can be an in-BSS NAV. In example 1500, STA 1513 can receive a second frame indicating the termination of the silent time interval during the silent time interval. Based on receiving the second frame, STA 1513 can terminate the silent time interval. In an embodiment, STA 1513 can reset its NAV based on receiving the second frame indicating the termination of the silent time interval. In an embodiment, STA 1513 can transmit a third frame to AP 1510 using EDCA channel access after terminating the silent time interval. The third frame can be one of a data frame, a control frame, or a management frame.

[0220] Figure 16 An example of an aggregation control (A control) field that can be used to indicate the termination of a silent time interval is shown. In an embodiment, the AP may transmit a frame including an A control field indicating the termination of a silent time interval. A STA that receives a frame including an A control field indicating the termination of a silent time interval may terminate the current silent time interval. In an embodiment, the frame including an A control field indicating the termination of a silent time interval may be a broadcast frame. In an embodiment, the frame including an A control field indicating the termination of a silent time interval may be a QoS data frame or a QoS null frame.

[0221] In an embodiment, the A control field indicating the termination of a silent time interval may be a control field for the termination aggregation of a silent time interval (QIT A control field).

[0222] In an embodiment, as shown in instance 1602, the A control field indicating the termination of a silent time interval may include a control ID subfield, a silent time interval termination indication subfield, and reserved bits. The control ID subfield may be set to a value corresponding to the termination of a silent time interval. The silent time interval termination indication subfield may be set to 1 to indicate the termination of a silent time interval.

[0223] In another embodiment, as shown in instance 1604, the A control field indicating the termination of a silent time interval may include a control ID subfield and reserved bits. The control ID subfield may be set to a value corresponding to the termination of a silent time interval.

[0224] Figure 17 An example process 1700 according to an embodiment is shown. The example process 1700 is provided for illustrative purposes only and does not limit the embodiment. The example process 1700 may be performed by an AP.

[0225] As Figure 17 shown, the process 1700 may start at step 1710, which includes transmitting a first frame indicating the silent time intervals of one or more first STAs. The first frame may include a silent element indicating the silent time interval. The first frame may be a broadcast frame. In an embodiment, the first frame may be a beacon frame or a probe response frame.

[0226] In an embodiment, the silent element includes: a silent count field indicating the number of target beacon transmission times (TBTTs) of beacon time intervals until the start of the next silent time interval; a silent period field indicating the number of beacon time intervals between the start times of regularly scheduled silent time intervals defined by the silent element; a silent duration field indicating the duration of the silent time interval; and a silent offset field indicating the offset of the start time of the silent time interval from the TBTT specified by the silent count field.

[0227] In an embodiment, the first frame further indicates an r-TWT SP for r-TWT settings of one or more second STAs. In an embodiment, the silent time interval overlaps with a part of the r-TWT SP. In an embodiment, the first frame includes a TWT element indicating the r-TWT SP.

[0228] In an embodiment, the one or more first STAs include:

[0229] An STA that does not support r-TWT operation;

[0230] An STA that is a member of the configured r-TWT;

[0231] An STA that supports r-TWT operation but is not a member of the configured r-TWT;

[0232] An STA that is a member of the r-TWT but has no buffered data for one or more traffic identifiers (TIDs) indicated by the first frame; or

[0233] A legacy STA (e.g., a HE STA, a VHT STA, an HT STA, etc.).

[0234] Subsequently, step 1720 includes transmitting a second frame indicating the termination of the silent time interval to one or more first STAs during the silent time interval. The silent time interval may be the current silent time interval. The second frame may be one of a probe response frame, a control frame, a CF end frame, a QoS data frame, a QoS null frame, a TIM broadcast frame, or a beacon frame.

[0235] In an embodiment, when the second frame includes a QoS null frame or a QoS data frame, the second frame further includes an A control field indicating the termination of the silent time interval.

[0236] In an embodiment, process 1700 may further include determining that the r-TWT SP terminates during the silent time interval; and transmitting the second frame based on the determination. In an embodiment, the second frame indicates the termination of the r-TWT SP during the silent time interval.

[0237] In an embodiment, transmitting the second frame includes transmitting the second frame in response to determining that: the wireless medium is not used by one or more second STAs during the r-TWT SP; and the silent time interval overlaps with the r-TWT SP.

[0238] In another embodiment, transmitting the second frame includes transmitting the second frame in response to determining that: the silent time interval overlaps with the r-TWT SP; and the r-TWT SP terminates.

[0239] In an embodiment, process 1700 may further include transmitting a third frame indicating the termination of the r-TWT SP during a silent time interval. In an embodiment, transmitting the second frame includes transmitting the second frame aggregated with the third frame. In an embodiment, transmitting the second frame includes transmitting the second frame at an xIFS time interval after transmitting the third frame. In an embodiment, the third frame may be a QoS null frame with the End of Service Period (EOSP) field set to 1; a QoS data frame with the EOSP field set to 1; or a CF-End frame.

[0240] In an embodiment, process 1700 may further include receiving, in step 1730, from a STA among one or more first STAs, a third frame transmitted using EDCA. The third frame may be one of a data frame, a control frame, or a management frame.

[0241] Figure 18 Another example process 1800 according to an embodiment is shown. The example process 1800 is provided for illustrative purposes only and does not limit the embodiments. The example process 1800 may be performed by a STA.

[0242] As Figure 18 shown, the example process 1800 may begin at step 1810, which includes receiving from an AP a first frame indicating a silent time interval. In an embodiment, the first frame may include a silent element indicating the silent time interval. In an example, the first frame may be a beacon frame or a probe response frame. In an embodiment, the STA may set its NAV based on the length of the silent time interval.

[0243] In step 1820, process 1800 may include determining whether a second frame terminating the silent time interval is received during the silent time interval. If the answer is no, then process 1800 transitions to step 1850, where the STA may continue to use EDCA to defer channel access until the end of the silent time interval. Otherwise, process 1800 proceeds to step 1830, where the STA may terminate the current silent time interval in response to the second frame. In an embodiment, the STA may reset its NAV setting through the silent time interval after terminating the silent time interval. Subsequently, in step 1840, the STA may use EDCA to transmit a third frame. The third frame may be one of a data frame, a control frame, or a management frame.

[0244] In an embodiment, the first frame may further include a TWT element of an r-TWT SP indicating the r-TWT settings of one or more first STAs. In an embodiment, the silent time interval overlaps with a part of the r-TWT SP.

[0245] In an embodiment, the STA performing process 1800 may be:

[0246] STA that does not support r-TWT operation;

[0247] STA that is a member of the configured r-TWT;

[0248] STA that supports r-TWT operation but is not a member of the configured r-TWT;

[0249] STA that is a member of the r-TWT but has no buffered data for one or more traffic identifiers (TIDs) indicated by the first frame; or

[0250] Traditional STA (e.g., HE STA, VHT STA, HT STA, etc.).

[0251] Figure 19 Another example process 1900 according to an embodiment is shown. Example process 1900 is provided for illustrative purposes only and does not limit the embodiments. Example process 1900 may be performed by an AP.

[0252] As Figure 19 shown, process 1900 may begin at step 1910, which includes transmitting a first frame that includes a TWT element indicating one or more silent time intervals and / or a TWT element indicating one or more r-TWT SPs. In an example, the first frame may be a beacon frame or a probe response frame.

[0253] Subsequently, at step 1920, process 1900 may include determining whether the r-TWT SP should terminate or has terminated before its end time. If the answer is no, process 1900 may proceed to step 1930, where the AP may maintain the r-TWT SP. Otherwise, process 1900 may transition to optional step 1940, which includes transmitting a second frame indicating the termination of the r-TWT SP during the r-TWT Sp.

[0254] Subsequently, at step 1950, process 1900 may include transmitting a third frame to terminate the current silent time interval based on the determination of the termination of the r-TWT SP. The third frame terminates the silent time interval before its end time. In an embodiment, the third frame may be one of a probe response frame, a CF end frame, a control frame, a QoS data frame, a QoS null frame, a TIM broadcast frame, a beacon frame, or a management frame.

[0255] Finally, process 1900 may include optional step 1960, which includes receiving a fourth frame from a STA using EDCA. The STA may be a STA configured with a silent time interval that terminates the silent time interval based on the received third frame. The fourth frame may be one of a data frame, a control frame, or a management frame.

Claims

1. An access point AP, comprising: Processor; and a memory storing a computer program, which when executed by the processor causes the AP to: Transmit a first frame, the first frame including: A Target Wake Time TWT element indicating an r-TWT service period SP of a restricted Target Wake Time r-TWT setting for one or more first stations STA; and A silent element indicating a silent time interval overlapping with the r-TWT SP for one or more second STAs; During the r-TWT SP, transmit a Quality of Service QoS data frame or an empty frame, where the End of Service Period EOSP field is set to 1; and During the silent time interval, transmit a contention-free CF end frame to the one or more second STAs, the CF end frame indicating the termination of the silent time interval.

2. The AP according to claim 1, wherein the silent element includes a silent duration field indicating the duration of the silent time interval.

3. The AP according to claim 1, wherein the silent element includes a silent period field indicating the number of beacon time intervals between the start times of the scheduled silent time intervals defined by the silent element.

4. The AP according to claim 1, wherein the silent element includes: A silent count field indicating the number of Target Beacon Transmission Times TBTT of beacon time intervals until the start of the next silent time interval; and A silent offset field indicating the offset of the start time of the silent time interval from the TBTT specified by the silent count field.

5. The AP according to claim 1, wherein, The first frame includes a beacon frame or a probe response frame.

6. The AP according to claim 1, wherein When the computer program is executed by the processor, the computer program further causes the AP to receive a second frame from a STA among the one or more second STAs during the silent time interval, where the STA supports r-TWT operation.

7. A station STA, comprising: A processor; and A memory storing a computer program, which when executed by the processor causes the STA to: Receive a first frame from an access point AP, the first frame including: A Target Wake Time (TWT) element indicating an r-TWT service period (SP) of a restricted Target Wake Time (r-TWT) setting for one or more first Stations (STAs). and A silent element indicating a silent time interval overlapping with a part of the r-TWT SP; During the silent time interval, receive a contention-free CF end frame from the AP, the CF end frame indicating the termination of the silent time interval; and Terminate the silent time interval in response to the CF end frame; Wherein, when the computer program is executed by the processor, when the STA supports r-TWT operation, the computer program further causes the STA to: During the r-TWT SP, receive a Quality of Service QoS data frame or an empty frame from the AP, where the End of Service Period EOSP field is set to 1; and Transmit a second frame to the AP during the silent time interval.

8. The STA according to claim 7, wherein, The silent element includes a silent duration field indicating the duration of the silent time interval.

9. The STA according to claim 7, wherein The silent element includes a silent period field that indicates the number of beacon time intervals between the start times of the scheduling silent time intervals defined by the silent element.

10. The STA according to claim 7, wherein, The silent element includes: a silent count field that indicates the number of target beacon transmission times (TBTTs) of beacon time intervals until the start of the next silent time interval; and a stationary offset field that indicates the offset of the start time of the silent time interval from the TBTT specified by the silent count field.

11. The STA according to claim 7, wherein, When the computer program is executed by the processor, the computer program also causes the STA to set a Network Allocation Vector (NAV) based on the length of the silent time interval.

12. The STA according to claim 11, wherein When the computer program is executed by the processor, the computer program also causes the STA to reset the NAV based on receiving the CF-End frame from the AP.

13. The STA according to claim 7, wherein, The first frame includes a beacon frame or a probe response frame.

14. The STA according to claim 7, wherein When the computer program is executed by the processor, the computer program also causes the STA to transmit a third frame to the AP after receiving the CF-End frame.

15. The STA according to claim 14, wherein, The STA uses Enhanced Distributed Channel Access (EDCA) to transmit the third frame.

16. A non-transitory computer-readable medium including a computer program, which when executed by a processor of an access point (AP), causes the AP to: transmit a first frame that includes: A Target Wake Time (TWT) element that indicates a restricted Target Wake Time (r-TWT) service period (SP) for a restricted r-TWT setting of one or more first Stations (STAs). and a silent element that indicates, for one or more second STAs, a silent time interval overlapping with the r-TWT SP; during the r-TWT SP, transmit a Quality of Service (QoS) data frame or an empty frame, where the End of Service Period (EOSP) field is set to 1; and during the silent time interval, transmit a contention-free CF-End frame to the one or more second STAs, the CF-End frame indicating the termination of the silent time interval.

17. The non-transitory computer-readable medium according to claim 16, wherein, When the computer program is executed by the processor, the computer program also causes the AP to: during the silent time interval, receive a second frame from a STA among the one or more second STAs, where the STA supports r-TWT operation.

18. An access point (AP) that includes: Processor; and a memory storing a computer program, which when executed by the processor, causes the AP to: transmit a first frame that includes: a Target Wake Time (TWT) element that indicates an r-TWT service period (SP) of a restricted target wake time (r-TWT) setting for one or more first stations (STAs); and a silent element that indicates, for one or more second STAs, a silent time interval overlapping with the r-TWT SP; and during the silent time interval, transmit a contention-free CF-End frame to the one or more second STAs, the CF-End frame indicating the termination of the silent time interval, where the computer program also causes the AP to: during the r-TWT SP, transmit a second frame to a STA among the one or more first STAs; or During the r-TWT SP, a third frame is received from a STA among the one or more first STAs.

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