Scheduling a wireless station within a target wake time service period

Abstract

In some implementations, an access point (AP) establishes a constrained target wake time (TWT) session that includes at least one constrained TWT service period (SP) for peer-to-peer (P2P) communications. The AP admits a group of wireless stations (STAs) associated with the P2P communications as members of the constrained TWT session; obtains a transmission opportunity (TXOP) on the wireless channel during the at least one constrained TWT SP; and transmits a protection frame on the wireless channel that identifies one or more STAs of the group of STAs belonging to the constrained TWT session that are permitted to transmit or receive P2P communications on the wireless channel during the TXOP. The protection frame can also indicate to receiving devices other than the one or more identified STAs that the wireless channel is unavailable for at least a portion of the TXOP.

Description

[0001] Cross-references to related applications

[0002] This patent application claims priority to U.S. Provisional Patent Application No. 63 / 076,358, filed September 9, 2020; U.S. Provisional Patent Application No. 63 / 081,886, filed September 22, 2020; and U.S. Non-Provisional Application No. 17 / 461,670, filed August 30, 2021, all of which are assigned to the assignee of this application. All disclosures of the prior applications are considered part of this patent application and are incorporated herein by reference. Technical Field

[0003] This disclosure generally relates to wireless communications, and more specifically to allocating resources of a wireless network to one or more wireless communication devices during a Constrained Target Wake Time (TWT) service period (SP).

[0004] Related technical descriptions

[0005] A Wireless Local Area Network (WLAN) can be formed by one or more Access Points (APs) that provide a shared wireless communication medium for use by several client devices (also known as stations (STAs)). The basic building block of a WLAN conforming to the IEEE 802.11 family of standards is the Basic Service Set (BSS) managed by the AP. Each BSS is identified by a Basic Service Set Identifier (BSSID) advertised by the AP. The AP periodically broadcasts beacon frames to enable any STA within the AP's wireless range to establish or maintain a communication link with the WLAN.

[0006] Some wireless communication devices can be associated with peer-to-peer (P2P) communication. P2P communication may be associated with real-time applications with strict latency requirements (such as very low average latency, worst-case latency of a few to tens of milliseconds, and small jitter) and specific throughput requirements. WLAN ensures that P2P communication can be handled in a way that minimizes latency while meeting any specified performance requirements.

[0007] Overview

[0008] The systems, methods, and apparatus disclosed herein each have several innovative aspects, and no single aspect is solely responsible for the desired properties disclosed herein.

[0009] One innovative aspect of the subject matter described in this disclosure can be implemented as a method for wireless communication by a wireless communication device operating an access point (AP). In some implementations, the method includes establishing a constrained target wake-up time (TWT) session on a wireless channel, the constrained TWT session including at least one constrained TWT service period (SP) for peer-to-peer (P2P) communication. The method includes: admitting a group of radio stations (STAs) associated with P2P communication as members of the constrained TWT session; obtaining a transmission opportunity (TXOP) on the wireless channel during the at least one constrained TWT SP; and transmitting a guard frame on the wireless channel. The guard frame may identify one or more STAs in the group of STAs belonging to the constrained TWT session that are permitted to transmit or receive P2P communication on the wireless channel during the TXOP. The guard frame may also indicate to receiving devices other than the identified one or more STAs that the wireless channel is unavailable for at least a portion of the TXOP. In some instances, the STAs identified by the guard frame include fewer STAs than all STAs belonging to the group of STAs in the constrained TWT session.

[0010] In some implementations, the method may further include: determining that at least two of the identified STAs are associated with a P2P link; and allocating time or frequency resources to the at least two STAs during at least a portion of the constrained TWT SP. In some instances, the P2P link includes a Tunneling Direct Link Establishment (TDLS) link over the radio channel.

[0011] In some implementations, the protection frame includes a Clear Transmit (CTS) frame or a CTS to Self frame, instructing other receiving devices to set their corresponding Network Allocation Vector (NAV) to a period less than the TXOP. In some instances, this period covers the transit airtime of the scheduling frame transmitted by the AP plus one of the following: Point Coordination Function (PCF) Inter-Frame Interval (PIFS) duration, Extended Inter-Frame Interval (EIFS) duration, or Acknowledgment (ACK) timeout period. In some other implementations, the protection frame instructs each STA in the STA group belonging to the constrained TWT session and not identified by the protection frame to enter Power Saving (PS) mode based on the receipt of the protection frame. In some instances, the protection frame instructs the period during which each STA in the STA group belonging to the constrained TWT session and not identified by the protection frame remains in PS mode. In some other instances, the protection frame includes a trigger frame that includes the Association Identifier (AID) of each of the one or more identified STAs.

[0012] In some implementations, the method may further include transmitting one or more scheduling frames on the radio channel during the TXOP. Each scheduling frame may be configured to schedule the corresponding STA identified by the guard frame for P2P transmission on the radio channel during the corresponding scheduled opportunity period within the TXOP. In some instances, each scheduling frame indicates to receiving devices other than the corresponding STA the duration for setting their corresponding NAV to the corresponding scheduled opportunity. In some other instances, each scheduling frame includes a trigger frame that includes a per-user information field indicating the transmission scheduling of the corresponding STA. In some aspects, the per-user information field may also indicate the allowed duration of P2P transmissions to or from the corresponding STA.

[0013] In some implementations, the method may further include: listening to the radio channel during a corresponding scheduled opportunity period; and resuming the TXOP from the corresponding STA based on the detection that no P2P transmission is detected during the corresponding scheduled opportunity period. In some other implementations, the method may further include: receiving frames from one or more STAs identified by the guard frame based on a corresponding scheduled frame; determining whether the duration of the Network Allocation Vector (NAV) included in the received frame is less than the NAV duration indicated by the corresponding scheduled frame; and scheduling the transmission of the next scheduled frame in the one or more scheduled frames in response to determining that the NAV duration included in the received frame is less than the NAV duration indicated by the corresponding scheduled frame. In some instances, the timing of the transmission of the next scheduled frame may be based on the end of the NAV duration included in the received frame.

[0014] Another innovative aspect of the subject matter described in this disclosure can be implemented in a wireless access point (AP). The AP may include at least one modem, at least one processor communicatively coupled to the at least one modem, and at least one memory communicatively coupled to the at least one processor. The at least one memory may store processor-readable code configured, when executed by the at least one processor in conjunction with the at least one modem, to: establish a constrained TWT session on a wireless channel, the constrained TWT session including at least one constrained TWTSP for P2P communication. Execution of the processor-readable code is configured to: admit a group of wireless STAs associated with P2P communication as members of the constrained TWT session; obtain a transmission opportunity (TXOP) on the wireless channel during the at least one constrained TWT SP; and transmit a guard frame on the wireless channel. The guard frame may identify one or more STAs belonging to the constrained TWT session that are permitted to transmit or receive P2P communication on the wireless channel during the TXOP. The guard frame may also indicate to receiving devices other than the identified one or more STAs that the wireless channel is unavailable for at least a portion of the TXOP. In some instances, the STAs identified by the protection frame include fewer STAs than all STAs in the STA group belonging to the constrained TWT session.

[0015] In some implementations, execution of processor-readable code can also be configured to: determine that at least two of the identified STAs are associated with the P2P link; and allocate time or frequency resources to the at least two STAs during at least a portion of the constrained TWT SP. In some instances, the P2P link includes a Tunneling Direct Link Establishment (TDLS) link over the radio channel.

[0016] In some implementations, the guard frame includes a CTS frame or a CTS-to-self frame, instructing other receiving devices to set their corresponding NAV to a period shorter than the TXOP. In some instances, this period covers the transit airtime of the scheduling frame transmitted by the AP plus one of the following: PIFS duration, EIFS duration, or ACK timeout period. In some other implementations, the guard frame instructs each STA in the STA group belonging to the constrained TWT session and not identified by the guard frame to enter power saving (PS) mode based on the receipt of the guard frame. In some instances, the guard frame instructs the period during which each STA in the STA group belonging to the constrained TWT session and not identified by the guard frame remains in PS mode. In some other instances, the guard frame includes a trigger frame that includes the AID of each of the one or more identified STAs.

[0017] In some implementations, execution of processor-readable code can also be configured to transmit one or more scheduling frames on the radio channel during the TXOP. Each scheduling frame can be configured to schedule the corresponding STA identified by the guard frame for P2P transmission on the radio channel during the corresponding scheduled opportunity period within the TXOP. In some instances, each scheduling frame indicates to receiver devices other than the corresponding STA the duration for setting their corresponding NAV to the corresponding scheduled opportunity. In some other instances, each scheduling frame includes a trigger frame that includes a per-user information field indicating the transmission scheduling for the corresponding STA. In some aspects, the per-user information field may also indicate the allowed duration of P2P transmissions to or from the corresponding STA.

[0018] In some implementations, execution of processor-readable code may also be configured to: listen to the radio channel during a corresponding scheduled opportunity; and resume the TXOP from the corresponding STA based on the detection that no P2P transmission occurred during the corresponding scheduled opportunity. In some other implementations, execution of processor-readable code may also be configured to: receive frames from one or more STAs identified by the guard frame based on a corresponding scheduled frame; determine whether the duration of the NAV included in the received frame is less than the NAV duration indicated by the corresponding scheduled frame; and schedule the transmission of the next scheduled frame in the one or more scheduled frames in response to determining that the NAV duration included in the received frame is less than the NAV duration indicated by the corresponding scheduled frame. In some instances, the timing of the transmission of the next scheduled frame may be based on the end of the NAV duration included in the received frame. Brief description of the attached diagram

[0020] Details of one or more implementations of the subject matter described in this disclosure are set forth in the accompanying drawings and the following description. Other features, aspects, and advantages will become apparent from this description, the drawings, and the claims.

[0021] Figure 1 A schematic diagram of an example wireless communication network is shown.

[0022] Figure 2A An example Protocol Data Unit (PDU) is shown that can be used for communication between an Access Point (AP) and several Stations (STAs).

[0023] Figure 2B It shows Figure 2A Example fields in the PDU.

[0024] Figure 3A Another example PDU that can be used for communication between an AP and one or more STAs is shown.

[0025] Figure 3BAnother example PDU that can be used for communication between an AP and one or more STAs is shown.

[0026] Figure 4 An example Physical Layer Convergence Protocol (PLCP) Protocol Data Unit (PPDU) is shown that can be used for communication between an AP and several STAs.

[0027] Figure 5 A block diagram of an example wireless communication device is shown.

[0028] Figure 6A A block diagram of an example access point (AP) is shown.

[0029] Figure 6B A block diagram of an example station (STA) is shown.

[0030] Figure 7 A timing diagram is shown depicting an example wireless communication that supports constrained target wake-up time (TWT) service periods according to some implementations.

[0031] Figure 8 A timing diagram is shown depicting another example of wireless communication that supports constrained TWT service periods according to some implementations.

[0032] Figure 9-16 The flowchart illustrates an example process for supporting constrained TWT service periods for low latency or latency-sensitive traffic, based on some implementations.

[0033] Figure 17A An example structure of a TWT element that can be used for wireless communication is shown according to some implementations.

[0034] Figure 17B An example structure of a broadcast TWT parameter set field that can be used for wireless communication is shown, based on some implementations.

[0035] Figure 17C An example structure of the request type field in a broadcast TWT parameter set field that can be used for wireless communication, based on some implementations, is shown.

[0036] Figure 18 An example structure of a trigger frame that can be used for wireless communication is shown, based on some implementations.

[0037] Figure 19 A timing diagram is shown depicting an example wireless communication that supports constrained TWT service periods for peer-to-peer (P2P) communication according to some other implementations.

[0038] Figure 20A timing diagram is shown depicting another example wireless communication that supports constrained TWT service periods for P2P communication according to some other implementations.

[0039] Figure 21-26 The flowchart illustrates an example process for supporting wireless communication with constrained TWT service periods for P2P communication, based on some implementations.

[0040] Figure 27 A block diagram of an example wireless communication device based on some implementations is shown.

[0041] Similar reference numerals and naming conventions in the various figures indicate similar elements.

[0042] Detailed description

[0043] The following description is directed to certain implementations in order to describe aspects of the innovation of this disclosure. However, those skilled in the art will readily recognize that the teachings herein can be applied in many different ways. The described implementations can be implemented in accordance with the Institute of Electrical and Electronics Engineers (IEEE) 802.11 standard, the IEEE 802.15 standard, and as defined by the Bluetooth Special Interest Group (SIG). The described implementation can be implemented in any device, system, or network capable of transmitting and receiving radio frequency (RF) signals according to one or more of the following standards, or those published by the 3rd Generation Partnership Project (3GPP): Long Term Evolution (LTE), 3G, 4G, or 5G (New Radio (NR)). The described implementation can be implemented in any device, system, or network capable of transmitting and receiving RF signals according to one or more of the following technologies or techniques: Code Division Multiple Access (CDMA), Time Division Multiple Access (TDMA), Frequency Division Multiple Access (FDMA), Orthogonal FDMA (OFDMA), Single Carrier FDMA (SC-FDMA), Single User (SU) Multiple Input Multiple Output (MIMO), and Multi User (MU) MIMO. The described implementation can also be implemented using other wireless communication protocols or RF signals suitable for use in one or more of Wireless Personal Area Networks (WPANs), Wireless Local Area Networks (WLANs), Wireless Wide Area Networks (WWANs), or Internet of Things (IoT) networks.

[0044] Various implementations generally involve constrained target wake-up time (TWT) sessions on a wireless channel. Some implementations more specifically involve establishing constrained TWT sessions for peer-to-peer (P2P) traffic. In some implementations, an AP can establish a constrained TWT session on a wireless channel, which includes at least one constrained TWT SP during which the AP reserves the wireless channel for P2P communication. The AP can admit a group of STAs associated with the P2P communication as members of the constrained TWT session. The AP can obtain a transmission opportunity (TXOP) on the wireless channel and can transmit a guard frame on the wireless channel. The guard frame can identify one or more STAs in the group of STAs belonging to the constrained TWT session that are permitted to transmit or receive P2P communication on the wireless channel during the TXOP. In some implementations, the guard frame can indicate that the wireless channel is busy or unavailable for receiving devices other than one or more identified STAs for at least a portion of the TXOP. In some instances, the protection frame may be a Clear Transmit (CTS) frame or a CTS to Self frame, which instructs other receiving devices to set their corresponding Network Allocation Vector (NAV) to a period less than the TXOP. In some other instances, the protection frame may be a trigger frame that includes the AID of each of the one or more identified STAs.

[0045] In various implementations, the AP may transmit one or more scheduling frames on the radio channel during the TXOP. Each scheduling frame may be configured to schedule the corresponding STA identified by the guard frame for P2P transmission on the radio channel during the corresponding scheduled opportunity period within the TXOP. Each scheduling frame may also instruct receiving devices other than the corresponding STA to set their corresponding NAV to the duration of the corresponding scheduled opportunity. In some instances, each scheduling frame may be a trigger frame that includes a per-user information field indicating the transmission scheduling of the corresponding STA. In some aspects, the per-user information field may also indicate the allowed duration of P2P transmissions to or from the corresponding STA. In some implementations, the AP may receive frames from one or more of the identified STAs based on the corresponding scheduling frame; and may schedule the transmission of the next scheduling frame in response to determining that the NAV duration included in the received frame is less than the NAV duration indicated by the corresponding scheduling frame.

[0046] Specific implementations of the subject matter described in this disclosure can be implemented to achieve one or more of the following potential advantages. By establishing constrained TWT sessions for STAs associated with P2P communication or P2P links, the AP can use enhanced channel access mechanisms, resource reservation mechanisms, and scheduling techniques to provide STAs as members of the constrained TWT sessions with more predictable latency, reduced worst-case latency, reduced jitter, and increased throughput. In this way, the AP can ensure that such STAs have sufficient access to the wireless channel to meet the stringent end-to-end latency, throughput, and packet loss requirements associated with P2P communication.

[0047] Figure 1 A block diagram of an example wireless communication network 100 is shown. Depending on some aspects, the wireless communication network 100 may be an example of a wireless local area network (WLAN) (such as a Wi-Fi network) (and will be referred to WLAN 100 below). For example, WLAN 100 may be a network implementing at least one of the IEEE 802.11 standard family (such as standards defined by the IEEE 802.11-2016 specification or its amendments, including but not limited to 802.11ah, 802.11ad, 802.11ay, 802.11ax, 802.11az, 802.11ba, and 802.11be). WLAN 100 may include numerous wireless communication devices, such as access points (APs) 102 and multiple stations (STAs) 104. Although only one AP 102 is shown, WLAN 100 may also include multiple APs 102.

[0048] Each STA 104 may also be referred to as a mobile station (MS), mobile device, mobile handheld device, wireless handheld device, access terminal (AT), user equipment (UE), subscriber station (SS), or subscriber unit, and other possibilities. STA 104 may represent a variety of devices such as mobile phones, personal digital assistants (PDAs), other handheld devices, netbooks, laptops, tablets, laptops, display devices (e.g., TVs, computer monitors, navigation systems, etc.), music or other audio or stereo devices, remote control devices (“remote controllers”), printers, kitchen or other household appliances, key fobs (e.g., for passive keyless entry and start (PKES) systems), and other possibilities.

[0049] A single AP 102 and its associated set of STAs 104 may be referred to as a Basic Service Set (BSS), which is managed by the corresponding AP 102. Figure 1Example coverage area 106 of AP 102 is also shown, which may represent the Basic Service Area (BSA) of WLAN 100. The BSA can be identified to users by a Service Set Identifier (SSID) and to other devices by a Basic Service Set Identifier (BSSID), which may be the Media Access Control (MAC) address of AP 102. AP 102 periodically broadcasts a beacon frame (“beacon”) including the BSSID to enable any STA 104 within the wireless range of AP 102 to “associate” or reassociate with AP 102 to establish or maintain a corresponding communication link 108 with AP 102 (also referred to hereinafter as a “Wi-Fi link”). For example, the beacon may include an identifier of the primary channel used by the corresponding AP 102 and a timing synchronization function for establishing or maintaining timing synchronization with AP 102. AP102 can provide access to external networks to each STA 104 in the WLAN via the corresponding communication link 108.

[0050] In order to establish a communication link 108 with AP 102, each STA 104 is configured to perform passive or active scanning operations (“scanning”) on frequency channels in one or more frequency bands (e.g., 2.4 GHz, 5.0 GHz, 6.0 GHz, or 60 GHz bands). To perform a passive scan, STA 104 listens for beacons transmitted by the corresponding AP 102 at periodic time intervals (referred to as Target Beacon Transmission Time (TBTT) (measured in units of time (TU), where one TU can be equal to 1024 microseconds (μs)). To perform an active scan, STA 104 generates probe requests and transmits these probe requests sequentially on each channel to be scanned, and listens for probe responses from AP 102. Each STA 104 can be configured to identify or select an AP 102 to associate with based on scan information obtained through passive or active scanning, and perform authentication and association operations to establish a communication link 108 with the selected AP 102. At the end of the association operation, AP 102 assigns an Association Identifier (AID) to STA 104, which AP 102 uses to track STA 104.

[0051] As wireless networks become increasingly prevalent, STA 104 can have the opportunity to choose from one of many BSSs within its range or from multiple APs 102 that together form an Extended Service Set (ESS) (comprising multiple connected BSSs). The extended network station associated with WLAN 100 can be connected to a wired or wireless distribution system that allows multiple APs 102 to be connected in such an ESS. Thus, STA 104 can be covered by more than one AP 102 and can be associated with different APs 102 at different times for different transmissions. Additionally, after being associated with an AP 102, STA 104 can also be configured to periodically scan its surroundings to find a more suitable AP 102 to associate with. For example, a STA 104 moving relative to its associated AP 102 can perform a "roaming" scan to find another AP 102 with more suitable network characteristics, such as a larger Received Signal Strength Indicator (RSSI) or reduced traffic load.

[0052] In some scenarios, STA 104 can form a network without AP 102 or other equipment besides STA 104 itself. An example of such a network is an ad hoc network (or wireless ad hoc network). Ad hoc networks are alternatively referred to as mesh networks or peer-to-peer (P2P) networks. In some scenarios, ad hoc networks can be implemented within a larger wireless network (such as WLAN 100). In such implementations, while STA 104 can communicate with each other via communication link 108 through AP 102, STA 104 can also communicate directly with each other via direct wireless link 110. Furthermore, two STA 104 can communicate via direct communication link 110, regardless of whether the two STA 104 are associated with and served by the same AP 102. In such ad hoc systems, one or more STA 104 can assume the role played by AP 102 in the BSS. Such STA 104 can be referred to as the group owner (GO) and can coordinate transmissions within the ad hoc network. Examples of direct wireless links 110 include Wi-Fi Direct connections, connections established using Wi-Fi Tunneling Direct Link Establishment (TDLS) links, and other P2P group connections.

[0053] AP 102 and STA 104 can operate and communicate (via the corresponding communication link 108) according to the IEEE 802.11 standard family (such as standards defined by the IEEE 802.11-2016 specification or its revisions, including but not limited to 802.11ah, 802.11ad, 802.11ay, 802.11ax, 802.11az, 802.11ba, and 802.11be). These standards define the WLAN radio and baseband protocols used for the PHY and Media Access Control (MAC) layers. AP 102 and STA 104 transmit and receive wireless communications (also referred to below as "Wi-Fi communication") to and from each other in the form of Physical Layer Convergence Protocol (PLCP) Protocol Data Units (PPDUs). AP 102 and STA 104 in WLAN 100 can transmit PPDUs on unlicensed spectrum, which can be a portion of the spectrum including bands traditionally used by Wi-Fi technologies, such as the 2.4 GHz band, 5.0 GHz band, 60 GHz band, 3.6 GHz band, and 900 MHz band. Some implementations of AP 102 and STA 104 described herein can also communicate in other bands, such as the 6.0 GHz band, that can support both licensed and unlicensed communication. AP 102 and STA 104 can also be configured to communicate on other bands, such as shared licensed bands, where multiple operators may have licenses to operate in one or more of the same or overlapping bands.

[0054] Each frequency band may include multiple sub-bands or frequency channels. For example, PPDUs conforming to revisions of the IEEE 802.11n, 802.11ac, and 802.11ax standards can be transmitted in the 2.4 GHz and 5.0 GHz bands, where each band is divided into multiple 20 MHz channels. Thus, these PPDUs are transmitted on physical channels with a minimum bandwidth of 20 MHz, but larger channels can be formed through channel bonding. For example, PPDUs can be transmitted on physical channels with bandwidths of 40 MHz, 80 MHz, 160 MHz, or 320 MHz by bonding multiple 20 MHz channels together.

[0055] Each PPDU is a composite structure comprising a PHY preamble and a payload in the form of a PLCP Service Data Unit (PSDU). The information provided in the preamble can be used by the receiving equipment to decode subsequent data in the PSDU. In instances where the PPDU is transmitted over a bonded channel, the preamble field may be copied and transmitted in each of the multiple component channels. The PHY preamble may include both a legacy portion (or "legacy preamble") and a non-legacy portion (or "non-legacy preamble"). The legacy preamble can be used for packet detection, automatic gain control, and channel estimation, among other applications. The legacy preamble is also generally used to maintain compatibility with legacy equipment. The format, decoding, and information provided in the non-legacy portion of the preamble are based on the specific IEEE 802.11 protocol to be used for transmitting the payload.

[0056] Figure 2A An example Protocol Data Unit (PDU) 200 for communication between an AP and several STAs is shown. For example, PDU 200 can be configured as a PPDU. As shown, PDU 200 includes a PHY preamble 202 and a PHY payload 204. For example, the PHY preamble 202 may include a legacy portion, which itself includes a legacy short training field (L-STF) 206, a legacy long training field (L-LTF) 208, and a legacy signaling field (L-SIG) 210. The PHY preamble 202 may also include one or more non-legacy fields 212. L-STF 206 generally enables the receiver equipment to perform automatic gain control (AGC) and coarse timing and frequency estimation. L-LTF 208 generally enables the receiver equipment to perform fine timing and frequency estimation, and also to estimate the radio channel. L-SIG 210 generally enables the receiver equipment to determine the duration of the PDU and use the determined duration to avoid transmission over the PDU. For example, L-STF 206, L-LTF 208, and L-SIG 210 can be modulated according to a binary phase shift keying (BPSK) modulation scheme. Payload 204 can carry data 214 and can be modulated according to a BPSK modulation scheme, a quadrature BPSK (Q-BPSK) modulation scheme, a quadrature amplitude modulation (QAM) modulation scheme, or another appropriate modulation scheme. Payload 204 can generally carry higher-layer data (e.g., in the form of Media Access Control (MAC) Protocol Data Units (MPDUs) or Aggregated MPDUs (A-MPDUs).

[0057] Figure 2B It shows Figure 2AExample L-SIG 220 in the PDU. L-SIG 220 includes a data rate field 222, reserved bits 224, a length field 226, parity bits 228, and a tail field 230. The data rate field 222 indicates the data rate (note that the data rate indicated in the data rate field 222 may not be the actual data rate of the data carried in the payload 204). The length field 226 indicates the packet length, for example, in bytes. The parity bits 228 are used to detect bit errors. The tail field 230 includes tail bits that are used by the receiving device to terminate the operation of the decoder (e.g., the Viterbi decoder). The receiving device uses the data rate and length indicated in the data rate field 222 and the length field 226 to determine the packet duration, for example, in microseconds (μs).

[0058] Figure 3A Another example PDU 300 is shown that can be used for wireless communication between an AP and one or more STAs. The PDU 300 can be used for SU, OFDMA, or MU-MIMO transmissions. The PDU 300 can be formatted as a High Efficiency (HE) WLAN PPDU according to the IEEE 802.11ax revision of the IEEE 802.11 wireless communication protocol standard. The PDU 300 includes a PHY preamble comprising a legacy portion 302 and a non-legacy portion 304. The PDU 300 may further include a PHY payload 306 (e.g., in the form of a PSDU including a data field 324) after the preamble.

[0059] The legacy portion 302 of the preamble includes L-STF 308, L-LTF 310, and L-SIG 312. The non-legacy portion 304 includes a repetition of L-SIG (RL-SIG) 314, a first HE signal field (HE-SIG-A) 316, a short HE training field (HE-STF) 320, and one or more long HE training fields (or symbols) (HE-LTF) 322. For OFDMA or MU-MIMO communication, the second portion 304 further includes a second HE signal field (HE-SIG-B) 318 encoded separately from HE-SIG-A 316. As with L-STF 308, L-LTF 310, and L-SIG 312, in instances involving the use of bonded channels, the information in RL-SIG 314 and HE-SIG-A 316 can be copied and transmitted in each component 20MHz channel. In contrast, the contents of HE-SIG-B 318 can be unique for each 20MHz channel and target-specific STA 104.

[0060] RL-SIG 314 indicates to HE-compatible STA 104 that PDU 300 is an HE PPDU. AP 102 can use HE-SIG-A316 to identify multiple STAs 104 and notify them that the AP has scheduled UL or DL ​​resources for them. For example, HE-SIG-A 316 may include a resource allocation subfield indicating the resource allocation for the identified STA 104. HE-SIG-A 316 can be decoded by each HE-compatible STA 104 served by AP 102. For MU transmissions, HE-SIG-A 316 further includes information that can be used by each identified STA 104 to decode the associated HE-SIG-B 318. For example, HE-SIG-A 316 may indicate the frame format (including the location and length of HE-SIG-B318), available channel bandwidth, modulation and coding scheme (MCS), and other examples. HE-SIG-A 316 may also include HE WLAN signaling information that can be used by STA 104 other than the identified STA 104.

[0061] HE-SIG-B 318 may carry STA-specific scheduling information, such as, for example, STA-specific (or "user-specific") MCS values ​​and STA-specific RU allocation information. In the context of DL MU-OFDMA, this information enables the corresponding STA 104 to identify and decode the corresponding Resource Unit (RU) in the associated data field 324. Each HE-SIG-B 318 includes a common field and at least one STA-specific field. The common field may indicate RU allocations (including RU assignments in the frequency domain) for multiple STAs 104, indicating which RUs are allocated for MU-MIMO transmissions and which RUs correspond to MU-OFDMA transmissions, as well as the number of users in the allocation and other examples. The common field may be encoded with common bits, CRC bits, and tail bits. The user-specific field is assigned to a specific STA 104 and can be used to schedule a specific RU and indicate that scheduling to other WLAN devices. Each user-specific field may include multiple user block fields. Each user block field may include two user fields, which contain information about the corresponding RU payload in the two corresponding STA decoding data fields 324.

[0062] Figure 3BAnother example PDU 350 is shown that can be used for wireless communication between an AP and one or more STAs. The PDU 350 can be used for SU, OFDMA, or MU-MIMO transmissions. The PDU 350 can be formatted as an Extremely High Throughput (EHT) WLAN PPDU according to the IEEE 802.11be revision of the IEEE 802.11 wireless communication protocol standard, or it can be formatted as a PPDU of any future (post-EHT) version conforming to a new wireless communication protocol (conforming to future IEEE 802.11 wireless communication protocol standards or other wireless communication standards). The PDU 350 includes a PHY preamble comprising a legacy portion 352 and a non-legacy portion 354. The PDU 350 may further include a PHY payload 356 (e.g., in the form of a PSDU including a data field 374) after the preamble.

[0063] The legacy portion 352 of the preamble includes L-STF 358, L-LTF 360, and L-SIG 362. The non-legacy portion 354 of the preamble includes RL-SIG 364 and signal fields associated with various wireless communication protocol versions following RL-SIG 364. For example, the non-legacy portion 354 may include a general signal field 366 (referred to herein as "U-SIG366") and an EHT signal field 368 (referred to herein as "EHT-SIG 368"). One or both of U-SIG 366 and EHT-SIG368 may be configured for other wireless communication protocol versions above EHT and carry information related to that version. The non-legacy portion 354 further includes an additional short training field 370 (referred to herein as "EHT-STF 370," but may also be configured for other wireless communication protocol versions above EHT and carry information related to that version) and one or more additional long training fields 372 (referred herein as "EHT-LTF 372," but may be configured for other wireless communication protocol versions above EHT and carry information related to that version). Similar to L-STF 358, L-LTF 360, and L-SIG 362, in instances involving the use of bonded channels, the information in U-SIG 366 and EHT-SIG 368 may be copied and transmitted in each component 20MHz channel. In some implementations, EHT-SIG 368 may additionally or alternatively carry information different from that carried in the primary 20MHz channel in one or more non-primary 20MHz channels.

[0064] EHT-SIG 368 may include one or more jointly encoded symbols and may be encoded in a block different from the block in which U-SIG 366 is encoded. EHT-SIG 368 may be used by the AP to identify multiple STAs 104 and to notify those STAs that the AP has scheduled UL or DL ​​resources for them. EHT-SIG 368 may be decoded by each compatible STA 104 served by AP 102. EHT-SIG 368 may generally be used by the receiving device to interpret the bits in data field 374. For example, EHT-SIG 368 may include RU allocation information, spatial flow configuration information, and per-user signaling information (such as MCS) and other examples. EHT-SIG 368 may further include a Cyclic Redundancy Check (CRC) (e.g., 4 bits) and a tail (e.g., 6 bits) that may be used for binary convolutional codes (BCC). In some implementations, EHT-SIG 368 may include one or more code blocks, each containing a CRC and a tail. In some aspects, each code block may be encoded individually.

[0065] EHT-SIG 368 can carry STA-specific scheduling information, such as, for example, user-specific MCS values ​​and user-specific RU allocation information. EHT-SIG 368 can generally be used by the receiving device to interpret the bits in data field 374. In the context of DL MU-OFDMA, this information enables the corresponding STA 104 to identify and decode the corresponding RU in the associated data field 374. Each EHT-SIG 368 may include a common field and at least one user-specific field. The common field may indicate the RU distribution across multiple STAs 104, indicate RU assignment in the frequency domain, indicate which RUs are allocated for MU-MIMO transmissions and which RUs correspond to MU-OFDMA transmissions, and the number of users in the allocation, among other examples. The common field may be encoded with common bits, CRC bits, and tail bits. The user-specific field is assigned to a specific STA 104 and can be used to schedule specific RUs and indicate this scheduling to other WLAN devices. Each user-specific field may include multiple user block fields. Each user block field may include, for example, two user fields containing information for the two corresponding STAs to decode their respective RU payloads.

[0066] The presence of RL-SIG 364 and U-SIG 366 ensures compatibility with EHT or later versions. STA 104 indicates that PPDU350 is an EHT PPDU or any later (post-EHT) version of a PPDU that conforms to a new wireless communication protocol (compliant with the future IEEE 802.11 wireless communication protocol standard). For example, U-SIG 366 can be used by the receiving device to interpret bits in one or more of EHT-SIG 368 or data field 374.

[0067] Figure 4 An example PPDU 400 is shown that can be used for communication between AP 102 and several STAs 104. As described above, each PPDU 400 includes a PHY preamble 402 and a PSDU 404. Each PSDU 404 may carry one or more MAC Protocol Data Units (MPDUs), such as an aggregated MPDU (A-MPDU) 406 including multiple MPDU subframes 408. Each MPDU subframe 408 may carry an MPDU 410, which includes a MAC delimiter 412 and a MAC header 414 preceding the accompanying frame body 416 (which includes the data portion or "payload" of the MPDU). The frame body 416 may carry one or more MAC Service Data Units (MSDUs), such as an aggregated MSDU (A-MSDU) 422 including multiple MSDU subframes 424. Each MSDU subframe 424 contains a corresponding MSDU 426, which includes a subframe header 428, a frame body 430, and one or more padding bits 432.

[0068] Referring back to MPDU 410, MAC header 414 may include several fields containing information defining or indicating the characteristics or attributes of the data encapsulated within frame body 416. MAC header 414 may also include several fields indicating the address of the data encapsulated within frame body 416. For example, MAC header 414 may include a combination of source address, sender address, receiver address, or destination address. MAC header 414 may include a frame control field containing control information. The frame control field specifies the frame type, such as a data frame, control frame, or management frame. MAC header 414 may further include a duration field indicating the duration from the end of the PPDU until the acknowledgment (ACK) of the last PPDU to be transmitted by the wireless communication device (e.g., block ACK (BA) in the case of an A-MPDU). The duration field is used to preserve the indicated duration of the wireless medium, thereby establishing NAV. Each MPDU 410 may also include a Frame Check Sequence (FCS) field 418 for error detection. For example, FCS field 418 may include cyclic redundancy check (CRC) and may be followed by one or more padding bits 420.

[0069] As described above, AP 102 and STA 104 can support multi-user (MU) communication. That is, concurrent transmission from one device to each of multiple devices (e.g., multiple simultaneous downlink (DL) communications from AP 102 to corresponding STA 104s), or concurrent transmission from multiple devices to a single device (e.g., multiple simultaneous uplink (UL) transmissions from corresponding STA 104s to AP 102). To support MU transmission, AP 102 and STA 104 can utilize multi-user multiple-input multiple-output (MU-MIMO) and multi-user orthogonal frequency division multiple access (MU-OFDMA) technologies.

[0070] In the MU-OFDMA scheme, the available spectrum of the radio channel can be divided into multiple resource elements (RUs), each comprising several different frequency subcarriers (“frequency modulo”). Different RUs can be allocated by AP 102 at specific times or assigned to different STAs 104. The size and distribution of RUs are referred to as RU allocation. In some implementations, RUs can be allocated in 2MHz intervals, and thus, the minimum RU can include 26 frequency moduloes, comprising 24 data frequency moduloes and 2 pilot frequency moduloes. Therefore, in a 20MHz channel, up to 9 RUs (such as 2MHz, 26-frequency modulo RUs) can be allocated (because some frequency moduloes are reserved for other purposes). Similarly, in a 160MHz channel, up to 74 RUs can be allocated. Larger RUs of 52, 106, 242, 484, and 996 frequency moduloes can also be allocated. Adjacent RUs can be separated by empty subcarriers (such as DC subcarriers) to reduce interference between adjacent RUs, reduce receiver DC offset, and avoid leakage of the transmit center frequency.

[0071] For UL MU transmissions, AP 102 can transmit trigger frames to initiate and synchronize UL MU-OFDMA or UL MU-MIMO transmissions from multiple STAs 104 to AP 102. Such trigger frames thus enable multiple STAs 104 to concurrently send UL traffic to AP 102 in time. The trigger frame can address one or more STAs 104 via a corresponding Association Identifier (AID), and can assign one or more RUs to each AID (and thus to each STA 104), which can be used to send UL traffic to AP 102. The AP can also specify one or more Random Access (RA) RUs that are contentious for by unscheduled STAs 104.

[0072] Figure 5 A block diagram of an example wireless communication device 500 is shown. In some implementations, the wireless communication device 500 may be for STAs (such as those mentioned above). Figure 1Examples of devices in one of the described STAs 104. In some other implementations, the wireless communication device 500 may be for an AP (such as those described above). Figure 1 Example of a device in the described AP 102. Wireless communication device 500 is capable of transmitting (or outputting for transmission) and receiving wireless communications (e.g., in the form of wireless packets). For example, wireless communication device 500 may be configured to transmit and receive packets in the form of Physical Layer Convergence Protocol (PLCP) Protocol Data Units (PPDUs) and Media Access Control (MAC) Protocol Data Units (MPDUs) conforming to IEEE 802.11 standards (such as those defined by the IEEE 802.11-2016 specification or its amendments, including but not limited to 802.11ah, 802.11ad, 802.11ay, 802.11ax, 802.11az, 802.11ba, and 802.11be).

[0073] The wireless communication device 500 may be or may include a chip, system-on-a-chip (SoC), chipset, package, or device that includes one or more modems 502 (e.g., a Wi-Fi (compliant with IEEE 802.11) modem). In some implementations, the one or more modems 502 (collectively, "modem 502") additionally include a WWAN modem (e.g., a 3GPP 4G LTE or 5G compatible modem). In some implementations, the wireless communication device 500 also includes one or more radios 504 (collectively, "radio 504"). In some implementations, the wireless communication device 500 further includes one or more processors, processing blocks, or processing elements 506 (collectively, "processor 506") and one or more memory blocks or elements 508 (collectively, "memory 508").

[0074] Modem 502 may include intelligent hardware blocks or devices, such as, for example, application-specific integrated circuits (ASICs). Modem 502 is generally configured to implement the PHY layer. For example, modem 502 is configured to modulate packets and output modulated packets to radio 504 for transmission over a wireless channel. Modem 502 is similarly configured to receive modulated packets received by radio 504 and demodulate the packets to provide demodulated packets. In addition to modulators and demodulators, modem 502 may further include digital signal processing (DSP) circuitry, automatic gain control (AGC), encoders, decoders, multiplexers, and demultiplexers. For example, when in transmission mode, data acquired from processor 506 is provided to a decoder, which encodes the data to provide encoded bits. The encoded bits are then mapped to points in a modulation constellation (using a selected MCS) to provide modulated symbols. Subsequently, the modulated symbols can be mapped to several (N) SS One) spatial flow or several (N) STS (1) space-time stream. Subsequently, the modulated symbols in the corresponding space stream or space-time stream can be multiplexed, transformed via an inverse fast Fourier transform (IFFT) block, and then provided to the DSP circuitry for Tx windowing and filtering. The digital signal can then be provided to a digital-to-analog converter (DAC). The resulting analog signal can then be provided to an up-converter and ultimately to radio 504. In implementations involving beamforming, the modulated symbols in the corresponding space stream are pre-coded via a guiding matrix before being provided to the IFFT block.

[0075] In receive mode, the digital signal received from radio 504 is provided to a DSP circuitry system configured to acquire the received signal, for example, by detecting the presence of the signal and estimating the initial timing and frequency offset. The DSP circuitry system is further configured to digitally condition the digital signal, for example, using channel (narrowband) filtering, analog impairment conditioning (such as correcting I / Q imbalance), and applying digital gain to ultimately obtain a narrowband signal. The output of the DSP circuitry system can then be fed to an AGC, configured to use information extracted from the digital signal (e.g., in one or more received training fields) to determine an appropriate gain. The output of the DSP circuitry system is also coupled to a demodulator configured to extract modulated symbols from the signal and, for example, calculate the log-likelihood ratio (LLR) for each bit position of each subcarrier in each spatial stream. The demodulator is coupled to a decoder configured to process the LLR to provide decoded bits. The decoded bits from all spatial streams are then fed to a demultiplexer for demultiplexing. The demultiplexed bits can then be descrambled and provided to the MAC layer (processor 506) for processing, evaluation, or interpretation.

[0076] Radio 504 generally includes at least one radio frequency (RF) transmitter (or “transmitter chain”) and at least one RF receiver (or “receiver chain”), which may be combined into one or more transceivers. For example, the RF transmitter and receiver may include various DSP circuitry systems, each including at least one power amplifier (PA) and at least one low-noise amplifier (LNA). The RF transmitter and receiver may further be coupled to one or more antennas. For example, in some implementations, wireless communication device 500 may include or be coupled to multiple transmit antennas (each with a corresponding transmit chain) and multiple receive antennas (each with a corresponding receive chain). Symbols output from modem 502 are provided to radio 504, which then transmits these symbols via the coupled antennas. Similarly, symbols received via the antennas are acquired by radio 504, which then provides these symbols to modem 502.

[0077] Processor 506 may include intelligent hardware blocks or devices designed to perform the functions described herein, such as, for example, processing cores, processing blocks, central processing units (CPUs), microprocessors, microcontrollers, digital signal processors (DSPs), application-specific integrated circuits (ASICs), programmable logic devices (PLDs) (such as field-programmable gate arrays (FPGAs)), discrete gate or transistor logic, discrete hardware components, or any combination thereof. Processor 506 processes information received via radio 504 and modem 502, and processes information to be output via modem 502 and radio 504 for transmission over a channelless environment. For example, processor 506 may implement a control plane and a MAC layer, configured to perform various operations related to the generation and transmission of MPDUs, frames, or packets. The MAC layer is configured to perform or facilitate frame decoding and decoding, spatial multiplexing, space-time block decoding (STBC), beamforming, and OFDMA resource allocation, and other operations or techniques. In some implementations, processor 506 may generally control modem 502 to cause the modem to perform the various operations described above.

[0078] Memory 508 may include tangible storage media, such as random access memory (RAM) or read-only memory (ROM), or combinations thereof. Memory 508 may also store non-transient processor or computer-executable software (SW) code containing instructions that, when executed by processor 506, cause the processor to perform various operations described herein for wireless communication, including the generation, transmission, reception, and interpretation of MPDUs, frames, or packets. For example, the various functions of the components disclosed herein, or the various blocks or steps of the methods, operations, processes, or algorithms disclosed herein, may be implemented as one or more modules of one or more computer programs.

[0079] Figure 6A A block diagram of example AP 602 is shown. For example, AP 602 could be a reference... Figure 1 The described example implementation of AP102. AP 602 includes a wireless communication device (WCD) 610. For example, the wireless communication device 610 may be a reference... Figure 5 An example implementation of the described wireless communication device 500 is described. AP 602 also includes a plurality of antennas 620 coupled to the wireless communication device 610 for transmitting and receiving wireless communications. In some implementations, AP 602 additionally includes an application processor 630 coupled to the wireless communication device 610, and a memory 640 coupled to the application processor 630. AP 602 further includes at least one external network interface 650, which enables AP 602 to communicate with a core network or backhaul network to obtain access to external networks, including the Internet. For example, external network interface 650 may include one or both of a wired (e.g., Ethernet) network interface and a wireless network interface (such as a WWAN interface). Components of the foregoing can communicate directly or indirectly with other components of these components on at least one bus. AP 602 further includes a housing that encloses the wireless communication device 610, application processor 630, memory 640, and at least a portion of the antennas 620 and external network interface 650.

[0080] Figure 6B A block diagram of example STA 604 is shown. For example, STA 604 could be a reference... Figure 1 The described example implementation of STA 104. STA 604 includes wireless communication device 615. For example, wireless communication device 615 may be a reference... Figure 5An example implementation of the described wireless communication device 500. STA 604 also includes one or more antennas 625 coupled to the wireless communication device 615 for transmitting and receiving wireless communications. STA 604 additionally includes an application processor 635 coupled to the wireless communication device 615, and a memory 645 coupled to the application processor 635. In some implementations, STA 604 further includes a user interface (UI) 655 (such as a touchscreen or keyboard) and a display 665, which can be integrated with the UI 655 to form a touchscreen display. In some implementations, STA 604 may further include one or more sensors 675 (for example, one or more inertial sensors, accelerometers, temperature sensors, pressure sensors, or altitude sensors). Components of the foregoing can communicate directly or indirectly with other components of these components on at least one bus. STA 604 further includes a housing that encloses the wireless communication device 615, the application processor 635, the memory 645, and at least portions of the antenna 625, the UI 655, and the display 665.

[0081] Figure 7 A timing diagram depicting an example wireless communication 700 supporting constrained TWT service periods according to some implementations is shown. Figure 7 In the example, wireless communication 700 can be performed between the AP, three wireless stations STA1-STA3 associated with the AP, and one or more other STAs within the AP's communication range but not associated with the AP. The AP can be any of the above-described references. Figure 1 and 6A An example of the described AP 102 and AP 602. Each of the wireless stations STA1, STA2, and STA3 can be described in the above references. Figure 1 and 6B An example of STA 104 and STA 604 is described. Other STAs may also be described in the above examples. Figure 1 and 6B Examples of STA 104 and 604 are described. For simplicity, Figure 7 The example only depicts three stations STA1–STA3 associated with the AP. In some other implementations, the AP can be associated with a number of other STAs.

[0082] Before time t0, the AP can establish a constrained TWT session for one or more STAs associated with low latency or latency-sensitive traffic. As discussed, low latency or latency-sensitive traffic may include traffic originating from real-time applications with strict latency requirements, small jitter margins, and specific throughput metrics. A constrained TWT session may include one or more constrained TWT SPs during which the AP reserves access to the radio channel only for STAs that are members of (and therefore belong to) the constrained TWT session. The AP can use enhanced channel access protection and resource reservation mechanisms during one or more constrained TWT SPs to provide STAs belonging to the constrained TWT session with more predictable latency, reduced worst-case latency, reduced jitter, higher throughput, and improved reliability for low latency or latency-sensitive traffic (compared to conventional solutions).

[0083] In some implementations, the AP can select or identify groups of STAs associated with low latency or latency-sensitive traffic and admit these groups of STAs as members of a constrained TWT session. Figure 7 In the example, each of the wireless stations STA1–STA3 is associated with low latency or latency-sensitive traffic and is a member of a constrained TWT session established by the AP. The other STAs are not associated with low latency traffic and are not members of a constrained TWT session.

[0084] An AP can advertise a constrained TWT session by including a TWT element in a beacon frame transmitted to its associated STA over a radio channel. The TWT element can indicate the existence of a constrained TWT session, indicate that the constrained TWT session is associated with low-latency traffic, and indicate one or more parameters of the constrained TWT session. These parameters may include (but are not limited to) the duration of the constrained TWT SP, the duration of the constrained TWT wake-up interval, the operating channel associated with the constrained TWT session, and the target wake-up time associated with the constrained TWT session. In some aspects, these parameters may also indicate whether the constrained TWT session is a broadcast TWT session or a private TWT session, or whether the constrained TWT session is a peer-to-peer (P2P) TWT session.

[0085] In some implementations, the TWT element can indicate that a constrained TWT session is established for low-latency traffic corresponding to one or more selected traffic identifiers (TIDs). For example, in some instances, the selected TID might be associated with a Voice Access Class (AC_VO). In other instances, the selected TID might be associated with a Video Access Class (AC_VI). In some other cases, the TWT element can indicate that a constrained TWT session is established for low-latency traffic corresponding to a predefined label or belonging to a selected traffic flow. For example, in some instances, the predefined label or selected traffic flow might be identified by an IP5 tuple or an IPv6 flow label. In various implementations, the TWT element can declare or otherwise indicate one or more TIDs, labels, and / or traffic flows specified by the AP.

[0086] exist Figure 7 In the example, STA1 and STA2 are associated with low-latency traffic corresponding to the first set of TIDs, tags, and / or traffic flows, while STA3 is associated with low-latency traffic corresponding to a second set of TIDs, tags, and / or traffic flows different from the first set. When a corresponding STA receives a beacon frame (or other suitable management frame) carrying a TWT element (which indicates the establishment of a constrained TWT session for low-latency or latency-sensitive traffic corresponding to the first set of TIDs, tags, and / or traffic flows), the corresponding STA can request to join the constrained TWT session or become a member of it based on a match between the TID, tag, or traffic flow associated with the corresponding STA's low-latency traffic and the TID, tag, or traffic flow declared by the AP or in the TWT element carried in the beacon frame transmitted by the AP.

[0087] Specifically, each of STA1 and STA2 can send a request to the AP indicating that the corresponding STA is associated with low latency traffic corresponding to one or more selected IDs identified by the TWT element. In some instances, the AP can verify that the TID(s) corresponding to the traffic flow of each of STA1 and STA2 match the selected TIDs identified by the TWT element before accepting STA1 and STA2 as members of a constrained TWT session.

[0088] In some instances, the TWT element may also include an instruction that wireless communication devices not identified by the TWT element will terminate their respective TXOPs and terminate any associated transmissions on the wireless channel at or before the start of each constrained TWT SP. For example, Figure 7Other STAs described herein may terminate their TXOP at time t0 and end any associated UL transmissions on the radio channel, which corresponds to the start of the first constrained TWT SP of the constrained TWT session. In some respects, this indication may be in a TWT parameter information field carrying TWT elements, which are included in beacon frames, probe responses, association responses, reassociation responses, or other suitable management frames transmitted by the AP.

[0089] Before time t0, each of STA1-STA3 wakes up from power-saving mode or sleep state to listen for beacon frames and other management frames transmitted by the AP on the radio channel. Also before time t0, the AP uses an appropriate channel access mechanism (such as EDCA) to contend for channel access and acquires TXOP on the radio channel for at least a portion of the constrained TWT session.

[0090] At time t0, the AP transmits the first frame M1 on the wireless channel. The first frame M1 identifies one or more STAs belonging to the constrained TWT session that are permitted to contend for channel access during at least a first portion of the constrained TWT SP. In some instances, the first frame M1 may instruct wireless communication devices not identified by the first frame M1 to suppress contention for channel access for a specified time period after detecting or receiving the first frame M1. Examples of the specified time period may include (but are not limited to) the first portion of the constrained TWT SP, the duration of the constrained TWT SP, the duration of the TXOP obtained by the AP, or some other time period. In some other instances, the first frame M1 may also instruct wireless communication devices not identified by the first frame M1 to enter a power-saving mode based on the receipt of the first frame M1.

[0091] In some implementations, the first frame M1 can be a CTS frame. In some instances, the AP can set the Receiver Address (RA) of the CTS frame to a configured MAC address indicating a specified time period. The wireless communication devices receiving the CTS frame can decode the configured MAC address, determine the time period specified by or associated with the configured MAC address, and set the corresponding NAV for these wireless communication devices to the specified time period. In some aspects, setting the RA of the CTS frame to the configured MAC address can also indicate that STA1 and STA2 can ignore the CTS frame and therefore do not need to set the corresponding NAV for these wireless communication devices.

[0092] In other implementations, the first frame M1 may be a MU-RTS trigger frame including the Association Identifier (AID) of each identified STA. This MU-RTS trigger frame may also indicate a time period for which wireless communication devices not identified by this MU-RTS trigger frame should set their corresponding NAV to that time period. In some instances, the MU-RTS trigger frame may allocate time and frequency resources available for uplink transmission, downlink transmission, or both to one or more identified STAs. Although not explicitly stated in the original text... Figure 7 As shown, however, each of STA1 and STA2 can transmit frames (such as CTS frames or ACK frames) to acknowledge receipt of the MU-RTS trigger frame.

[0093] In some other implementations, the first frame M1 can be a BSRP trigger frame, carrying reserved bits or fields set to configured values. The BSRP trigger frame may include the AID values ​​of one or more identified STAs and may request reports of queued uplink (UL) data or queued P2P data from each of the one or more identified STAs.

[0094] for Figure 7 In the example, STA1 and STA2 are identified by the first frame M1, while STA3 is not. Thus, STA1 and STA2 can contend for channel access during at least a portion of the TXOP obtained by the AP. STA3 is not identified by the first frame M1 and does not contend for channel access during the TXOP obtained by the AP. Thus, STA3 can return to power-saving mode or sleep state at or before time t1.

[0095] At time t1, the AP transmits a second frame M2 on the radio channel. This second frame M2 identifies one or more STAs belonging to the constrained TWT session who are permitted to transmit or receive data on the radio channel during the first scheduled opportunity of the constrained TWT SP. Specifically, the second frame M2 can select one or more STAs identified by the first frame M1 to receive DL data or transmit UL data (or both) on the radio channel during the first scheduled opportunity of the constrained TWT SP. Figure 7 In the example, the second frame M2 selects or identifies STA1, and thus STA1 is allowed to contend for channel access and subsequently transmit or receive data on the wireless channel during the first scheduled opportunity. In an instance where STA1 is associated with P2P communication, the second frame M2 may carry instructions for STA1 to indicate when the transmission or reception of the P2P communication should end.

[0096] Although STA2 and STA3 are associated with low latency or latency-sensitive traffic and are members of a constrained TWT session, omitting STA2 and STA3 from the second frame M2 may prevent each of STA2 and STA3 from attempting to gain channel access during the first scheduled opportunity. In some instances, the second frame M2 can be a trigger frame, such as an MU-RTS trigger frame, a BSRP trigger frame, or a PS polling frame. In other instances, the second frame M2 can be a CTS frame. In some implementations, the time interval between the transmission of the first frame M1 and the second frame M2 can be at least the Arbitrated Interframe Spacing (AIFS).

[0097] At time t2, STA1 transmits or receives one or more first PPDUs 711 on the wireless channel, at least in part, based on the second frame M2. In some instances, STA1 may transmit one or more first PPDUs 711 as UL PPDUs to other wireless communication devices between time t2 and t3. In other instances, STA1 may receive one or more first PPDUs 711 as DL PPDUs from other wireless communication devices between time t2 and t3. In some still instances, STA1 may transmit one or more UL PPDUs concurrently with receiving one or more DL PPDUs on the wireless channel between time t2 and t3.

[0098] The AP can be configured to continuously or periodically monitor the radio channel for a period of time following the transmission of the second frame M2 to determine whether data transmission is present or absent on that channel. In this way, the AP can ensure that the radio channel is utilized during the first scheduled opportunity. This period can be indicated in the second frame M2. In some instances, this period can be the duration of the Arbitrated Inter-Frame Space (AIFS) plus the minimum contention window size (CW). min In other instances, this time period can be the Point Coordination Function (PCF) Inter-Frame Space (PIFS) duration. In some other instances, this time period can be any suitable variation of the IFS duration. If the AP does not detect any data transmission from STA1 on the radio channel during this time (which could indicate that STA1 has not received the second frame M2 or that STA1 is unable to transmit data), the AP can retransmit the second frame M2 to STA1 and can also transmit the third frame M3 to STA2 as a fault recovery operation (not shown for simplicity).

[0099] exist Figure 7In the example, STA1 completes the transmission or reception of one or more PPDU 711s at or before time t3. Then, between time t3 and t4, the AP can release the radio channel from STA1 based on the transmission duration of one or more PPDU 711s and any acknowledgment (ACK) frames that may follow the transmission of one or more PPDU 711s. For simplicity, in Figure 7 An ACK frame is not shown in the example. In some instances, the end of transmission of one or more PPDU 711 packets on a radio channel can be detected based on one or more indications carried in the packet preamble of the PPDU 711.

[0100] At time t4, the AP transmits a third frame M3 on the radio channel. This third frame M3 identifies one or more STAs belonging to the constrained TWT session who are permitted to transmit or receive data on the radio channel during the second scheduled opportunity of the constrained TWT SP. Specifically, the third frame M3 can select one or more STAs identified by the first frame M1 to receive DL data or transmit UL data (or both) on the radio channel during the second scheduled opportunity. Figure 7 In the example, the third frame M3 identifies STA2 for the second scheduled opportunity, and therefore STA2 is allowed to contend for channel access and subsequently transmit or receive data on the radio channel during the second scheduled opportunity. As shown, STA2 accesses the radio channel at or before time t5.

[0101] At time t5, STA2 transmits or receives one or more second PPDUs 712 on the radio channel, at least in part, based on the third frame M3. In some instances, STA2 may transmit one or more second PPDUs 712 as UL PPDUs to other wireless communication devices between time t5 and t6. In other instances, STA2 may receive one or more second PPDUs 712 as DL PPDUs from other wireless communication devices between time t5 and t6. In some still instances, STA2 may transmit one or more UL PPDUs concurrently with receiving one or more DL PPDUs on the radio channel between time t5 and t6.

[0102] At time t7, the constrained TWT SP ends, and STA3 can access the wireless channel. In some instances, STA3 can use a contention-based channel access mechanism (such as EDCA) to gain access to the wireless channel. Figure 7 In the example, STA3 gains access to the wireless channel at time t8 and transmits one or more UL PPDU 713s to the AP on the wireless channel between times t8 and t9. At time t... 10 The constrained TWT session ends.

[0103] Figure 8 A timing diagram depicting another example of a wireless communication 800 supporting constrained TWT service periods according to some implementations is shown. Figure 8 In the example, wireless communication 800 can be referenced. Figure 7 The described operation is performed between AP and STA. Figure 8 The timing diagram is similar to Figure 7 The timing diagram, in addition to Figure 8 In the example, the AP determines that each of STA1 and STA2 is associated with a P2P link. In some respects, the AP can classify STA1 and STA2 as P2P STAs based on their association with P2P links.

[0104] Before time t0, the AP can establish a constrained TWT session for one or more STAs associated with P2P traffic. A constrained TWT session can include one or more constrained TWT SPs, during which the AP reserves access to the radio channel only for STAs that are members of that constrained TWT session. The AP can use enhanced channel access protection and resource reservation mechanisms during one or more constrained TWT SPs to provide more predictable latency, reduced worst-case latency, reduced jitter, and increased reliability for P2P communication. In some implementations, the AP can admit one or more STAs (such as STA1 and STA2) associated with or classified as P2P devices to the constrained TWT session. Figure 8 In the example, each of STA1 and STA2 is associated with a P2P link and is a member of a constrained TWT session established or scheduled by the AP. STA3 and other STAs are not associated with a P2P link or are not classified as P2P devices, and are not members of a constrained TWT session.

[0105] At time t0, the AP transmits the first frame M1 on the wireless channel. The first frame M1 identifies one or more STAs belonging to the constrained TWT session who are permitted to contend for channel access during the first scheduled opportunity of the constrained TWT session. The first frame M1 can also instruct wireless communication devices not identified by the first frame M1 to suppress contention for channel access during TXOP (or during constrained TWT SP). In some other instances, the first frame M1 can instruct wireless communication devices not identified by the first frame M1 to enter a power-saving mode based on the receipt of the first frame M1. The first frame M1 can be a CTS frame, a MU-RTS trigger frame, a BSRP trigger frame, or any other frame that can identify one or more STAs and request UL data from the identified STAs. Figure 8In the example, the first frame M1 identifies STA1 and STA2, and therefore STA1 and STA2 are allowed to contend for channel access at least during the first scheduled opportunity of the constrained TWT session.

[0106] At time t1, the AP transmits a second frame M2 on the wireless channel. The second frame M2 selects or indicates one or more members of the constrained TWT session. The time interval between the transmission of the first frame M1 and the second frame M2 can be one or more suitable variations of the IFS duration. Specifically, the second frame M2 can select one or more STAs identified by the first frame M1 to receive DL data or transmit UL data (or both) on the wireless channel during the first scheduled opportunity. Figure 8 In the example, the second frame M2 selects or identifies STA1 and STA2, and thus STA1 and STA2 are allowed to contend for channel access and subsequently transmit or receive data on the radio channel during the first scheduled opportunity.

[0107] As discussed, the second frame M2 can be a trigger frame that allocates time or frequency resources to the STA resource identified by the second frame M2. The second frame M2 may also carry instructions for each of STA1 and STA2 to indicate when the P2P communication should end. In some instances, this instruction may be carried in the signal field of the preamble of the last PPDU transmitted from STA1 or STA2.

[0108] As shown in the figure, STA1 and STA2 exchange P2P communications 811 and 812 between t2 and t3. As discussed, the AP can be configured to continuously or periodically monitor the wireless channel for a period of time following the transmission of the second frame M2 to determine the presence or absence of data. This ensures that the wireless channel is utilized during the first scheduled opportunity of the constrained TWT SP. This time period can be indicated in the second frame M2. For Figure 8 For example, STA1 and STA2 complete P2P transmissions 811 and 812 at time t3. In some cases, the AP can detect the absence of data on the wireless channel after the P2P transmission ends at time t3. Then, between time t3 and t4, the AP releases the wireless channel from STA1 and STA2 based on the absence of data on the wireless channel between time t3 and t4.

[0109] At time t4, the AP transmits a third frame M3 on the radio channel. This third frame M3 selects or identifies one or more STAs belonging to the constrained TWT session who are permitted to transmit or receive data on the radio channel during the second scheduled opportunity of the constrained TWT SP. Specifically, the third frame M3 can select one or more STAs identified by the first frame M1 to receive DL data or transmit UL data (or both) on the radio channel during the second scheduled opportunity. Figure 8 In the example, the third frame M3 selects or identifies STA3, and thus STA3 is allowed to contend for channel access and subsequently transmit or receive data on the radio channel during the second scheduled opportunity of the constrained TWTSP. As shown, STA3 accesses the radio channel at or before time t5 and can transmit one or more UL PPDU813s on the radio channel between time t5 and t6.

[0110] At time t7, the constrained TWT SP ends. In some instances, the AP may not have any queued downlink data for any of STA1-STA3, and none of STA1-STA3 may have queued uplink data available for transmission to the AP. In some instances, the AP may allow one or more other STAs to access the radio channel, for example, to transmit data to or receive data from other wireless communication devices. Figure 8 In the example, other STAs gain access to the wireless channel at time t8 and transmit or receive one or more PPDU 814s on the wireless channel between times t8 and t9. At time t... 10 The constrained TWT session ends.

[0111] Figure 9 The diagram illustrates a flowchart of an example process 900 for supporting constrained TWT service periods for low latency or latency-sensitive traffic, based on some implementations. Process 900 can be implemented by a wireless communication device (such as referenced...) Figure 5 The described wireless communication device 500) performs the procedure. In some implementations, the procedure 900 can be performed by an AP (such as referred to separately). Figure 1 and Figure 6A The wireless communication device that operates or operates within the AP (either of the described APs 102 and 602) performs this function.

[0112] For example, in box 902, the AP establishes a constrained target wake-up time (TWT) session on the radio channel. The constrained TWT session includes at least one constrained TWT service period (SP) during which the AP reserves the radio channel for low latency or latency-sensitive traffic. In box 904, the AP identifies a group of radio stations (STAs) associated with the low latency or latency-sensitive traffic that belong to the established TWT session. In box 906, the AP obtains a transmission opportunity (TXOP) on the radio channel during the at least one constrained TWT SP. In box 908, the AP transmits a first frame on the radio channel, the first frame identifying one or more STAs belonging to the group of STAs in the constrained TWT session that are permitted to contend for channel access during the first scheduled opportunity of the constrained TWT SP.

[0113] In some implementations, the one or more identified STAs include fewer STAs than all STAs in the group of STAs belonging to the constrained TWT session. That is, in some instances, the first frame may identify or select a subset of members of the constrained TWT session who can access the radio channel during the constrained TWT SP. In this way, the AP can limit the number of STAs contending for channel access during a given time period, thereby increasing the likelihood that each STA identified by the first frame will obtain a TXOP on the radio channel.

[0114] In some implementations, the first frame indicates that the wireless channel is busy or unavailable for wireless communication devices not identified by the first frame. Additionally or alternatively, the first frame may indicate that wireless communication devices not identified by the first frame should suppress contention for channel access during at least the first scheduled opportunity.

[0115] The first frame can also instruct wireless communication devices not identified by the first frame to enter power-saving mode after receiving the first frame. In some instances, the first frame can instruct wireless communication devices not identified by the first frame to remain in power-saving mode for a specified period. In other instances, for each STA in a group of STAs belonging to a constrained TWT session and not identified by the first frame, the first frame can instruct channel access scheduling for a portion of the constrained TWT SP that occurs after the TXOP. Channel access scheduling can cover any suitable time period. In some aspects, channel access scheduling spans one or more distinct TXOPs within the constrained TWT SP.

[0116] In some other implementations, the first frame may be a CTS frame indicating a time period for which wireless communication devices other than one or more identified STAs must set their corresponding Network Allocation Vector (NAV). This time period may correspond to the duration of a TXOP, the duration of a first scheduled opportunity, or some other suitable time period. In instances where the first frame identifies only one STA, the Receiver Address (RA) of the CTS frame is set to the MAC address of that STA. In some other instances, the RA of the CTS frame may be set to a configured MAC address indicating that STAs belonging to a constrained TWT session are permitted to contend for channel access during the first scheduled opportunity.

[0117] In some other implementations, the first frame may be a trigger frame, which includes the AID value of each STA identified by the trigger frame. The trigger frame may allocate frequency resources to the STAs identified by the trigger frame for transmitting or receiving radio signals on the radio channel during the first scheduled opportunity. The trigger frame may also indicate a time period to which wireless communication devices not identified by the trigger frame should set their corresponding NAV. This time period may correspond to the duration of the TXOP, the duration of the first scheduled opportunity, or some other suitable time period. In some instances, the time period may be carried or indicated in the duration / ID field of the trigger frame. In some other instances, the indicated time period may be carried or indicated in the signal field of the preamble of the trigger frame.

[0118] In some instances, the trigger frame may be an MU-RTS trigger frame, which includes reserved bits or fields set to configured values. Each STA that receives the MU-RTS trigger frame may transmit a CTS frame to acknowledge receipt of the MU-RTS trigger frame. In some aspects, a CTS frame transmitted by an STA identified in the MU-RTS trigger frame can be used to prevent other wireless communication devices from accessing the wireless channel during an indicated time period. For example, the CTS frame may indicate the time period during which wireless communication devices not identified by the MU-RTS trigger frame will suppress contention for channel access. In some aspects, for example, the respective STA may transmit the CTS frame as multiple copies of a non-HT PPDU on multiple respective 20MHz channels or frequency subbands to prevent other wireless communication devices from accessing the wireless channel.

[0119] In some other instances, the trigger frame may be a BSRP trigger frame, which includes reserved bits or fields set to configured values. The BSRP trigger frame may request a report from each STA identified by the trigger frame for queued uplink (UL) data or queued P2P data. Each STA receiving the BSRP trigger frame may transmit a CTS frame to acknowledge receipt of the BSRP trigger frame. In some instances, the corresponding STA may transmit a Buffer Status Report (BSR) indicating the amount of queued UL data or queued P2P data in response to receiving the BSRP trigger frame. The AP may receive the BSR from each of the identified STAs and may determine the amount of queued data that each STA has relative to the other STAs. In some aspects, the AP may use the information contained in the received BSR to determine channel access scheduling for each STA.

[0120] Figure 10 A flowchart illustrating another example process 1000 for supporting constrained TWT service periods for low latency or latency-sensitive traffic, according to some implementations, is shown. Process 1000 can be implemented by a wireless communication device (such as referenced in the diagram). Figure 5 The described wireless communication device 500) performs the operation. In some implementations, process 1000 can be performed by an AP (such as referred to separately). Figure 1 and Figure 6A The process 1000 is performed by a wireless communication device that operates or operates within an AP (either of the described APs 102 and 602). In some instances, process 1000 may be... Figure 9 The action in block 908 is performed after the first frame is transmitted over the wireless channel. For example, in block 1002, the AP transmits or receives low-latency or latency-sensitive data to or from one or more STAs identified by the trigger frame during the first scheduled opportunity.

[0121] Figure 11 A flowchart illustrating another example process 1100 for supporting constrained TWT service periods for low latency or latency-sensitive traffic, according to some implementations, is shown. Process 1100 can be implemented by a wireless communication device (such as referenced...) Figure 5 The wireless communication device 500 described herein may be used to perform the process. In some implementations, process 1100 may be performed by an AP (such as referred to separately). Figure 1 and Figure 6A The process 1100 is performed by a wireless communication device that operates or operates within an AP (either of the described APs 102 and 602). In some instances, process 1100 may be performed by... Figure 9 The action in box 908 is performed after the first frame is transmitted over the wireless channel.

[0122] For example, in block 1102, the AP determines that two STAs identified by the trigger frame are associated with the P2P link. In block 1104, the AP classifies the STAs associated with the P2P link as P2P STAs. In block 1106, the AP allocates time or frequency resources to one or more of these P2P STAs during at least a portion of the constrained TWT SP. In some implementations, these P2P STAs may be Tunneled Direct Link Establishment (TDLS) peering STAs or Wi-Fi peering STAs. In some instances, the AP may estimate the duration of the P2P transmission between two P2P STAs. In some other instances, each P2P STA may indicate the end of the corresponding P2P transmission by providing predefined signals, flags, or bits during the P2P transmission.

[0123] Figure 12 A flowchart illustrating another example process 1200 for supporting constrained TWT service periods for low latency or latency-sensitive traffic, according to some implementations, is shown. Process 1200 can be implemented by wireless communication devices (such as references) Figure 5 The wireless communication device 500 described herein may be used to perform the process. In some implementations, the process 1200 may be performed by an AP (such as referred to separately). Figure 1 and Figure 6A The process 1200 is performed by a wireless communication device that operates or operates within an AP (either of the described APs 102 and 602). In some instances, process 1200 may be performed by... Figure 9 The action in box 908 is performed after the first frame is transmitted over the wireless channel.

[0124] For example, when an AP transmits a MU-RTS trigger frame to request UL transmission from one or more identified STAs, each of the identified STAs can acknowledge receipt of the MU-RTS frame by sending a CTS frame to the AP. In block 1202, the AP receives the CTS frame from each STA identified by the MU-RTS trigger frame.

[0125] Figure 13 A flowchart illustrating another example process 1300 for supporting constrained TWT service periods for low latency or latency-sensitive traffic, according to some implementations, is shown. Process 1300 can be implemented by wireless communication devices (such as references) Figure 5 The wireless communication device 500 described herein may be used to perform the process. In some implementations, process 1300 may be performed by an AP (such as referred to separately). Figure 1 and Figure 6A The wireless communication device that operates or operates within the AP (either of the described APs 102 and 602) is executed. In some instances, process 1300 may be performed by... Figure 9The first frame in box 908 is transmitted as a BSRP trigger frame on the wireless channel after the first frame is transmitted.

[0126] For example, in block 1302, the AP receives a Buffer Status Report (BSR) from each of one or more identified STAs based on a BSRP trigger frame. In block 1304, the AP schedules one or more identified STAs to access the radio channel based on the received BSR. The BSR may indicate the amount of data queued for transmission in the respective STA. The queued data may include queued UL data to be transmitted to the AP, or it may correspond to a P2P transmission.

[0127] Figure 14 A flowchart illustrating another example process 1400 for supporting constrained TWT service periods for low latency or latency-sensitive traffic, according to some implementations, is shown. Process 1400 can be implemented by wireless communication devices (such as references) Figure 5 The wireless communication device 500 described herein may perform the procedure. In some implementations, the procedure 1400 may be performed by an AP (such as referred to separately). Figure 1 and Figure 6A The process 1400 is performed by a wireless communication device that operates or operates within an AP (either of the described APs 102 and 602). In some instances, process 1400 may be performed by... Figure 9 The first frame in box 908 is transmitted as a BSRP trigger frame on the wireless channel after the first frame is transmitted.

[0128] For example, in block 1402, the AP transmits a second frame on the wireless channel, which selects a first STA from one or more STAs identified by the first frame to access the wireless channel during a first scheduled opportunity. In block 1404, the AP monitors the wireless channel for a period of time to determine whether data is present or absent. In some implementations, the first frame instructs the selected STA to contend for channel access after receiving the second frame. In some other implementations, the trigger frame may include a time window within which the selected STA is to transmit or receive low-latency data.

[0129] Figure 15 A flowchart illustrating another example process 1500 for supporting constrained TWT service periods for low latency or latency-sensitive traffic, according to some implementation, is shown. Process 1500 can be implemented by a wireless communication device (such as referenced...) Figure 5 The wireless communication device 500 described herein may perform the procedure. In some implementations, the procedure 1500 may be performed by an AP (such as referred to separately). Figure 1 and Figure 6A The process 1500 is performed by a wireless communication device that operates or operates within an AP (either of the described APs 102 and 602). In some instances, process 1500 may be performed by... Figure 14 The monitoring of the wireless channel in box 1404 is then performed.

[0130] For example, in block 1502, the AP transmits a third frame on the wireless channel before the end of the first scheduled opportunity, based on the absence of data on the wireless channel during the indicated time period. The third frame selects a second STA from among the STAs identified by the first frame to access the wireless channel for the remainder of the first scheduled opportunity. The second STA can contend for channel access and gain access to the wireless channel or medium during the remainder of the first scheduled opportunity.

[0131] Figure 16 A flowchart illustrating another example process 1600 for supporting constrained TWT service periods for low latency or latency-sensitive traffic, according to some implementations, is shown. Process 1600 can be implemented by wireless communication devices (such as references) Figure 5 The wireless communication device 500 described herein may perform the procedure. In some implementations, the procedure 1600 may be performed by an AP (such as referred to separately). Figure 1 and Figure 6A The process 1600 is performed by a wireless communication device that operates or operates within an AP (either of the described APs 102 and 602). In some instances, process 1600 may be performed by... Figure 14 The monitoring of the wireless channel in block 1404 is then performed. For example, in block 1602, the AP releases the wireless channel from the first STA based on the absence of data on the wireless channel during the specified time period. In block 1604, the AP transmits a third frame on the wireless channel at the end of the indicated time period based on the absence of data on the wireless channel during the specified time period. In some instances, the third frame may selectively allow a second STA among one or more STAs identified by the first frame to access the wireless channel for the remainder of the first scheduled opportunity.

[0132] Figure 17A An example structure of a TWT element 1700 for wireless communication, according to some implementations, is shown. The TWT element 1700 may include an element ID field 1702, a length field 1704, a control field 1706, and a TWT parameter information field 1708. The element ID field 1702 indicates that the element is a TWT element. The length field 1704 indicates the length of the TWT element 1700. The control field 1706 includes various control information for a bounded TWT session declared by the TWT element 1700. The TWT parameter information field 1708 contains a single individual TWT parameter set field or one or more broadcast TWT parameter set fields.

[0133] Figure 17BAn example structure of a broadcast TWT parameter set field 1710 for use in wireless communication, according to some implementations, is shown. In some instances, the broadcast TWT parameter set field 1710 may be included... Figure 17A The TWT parameter information field 1708 is included. The broadcast TWT parameter set field 1710 may include a request type field 1712, a target wake-up time field 1714, a nominal minimum TWT wake-up duration field 1716, a TWT wake-up interval tail number field 1717, and a broadcast TWT information field 1718. The request type field 1712 indicates the type of the requested TWT session. The target wake-up time field 1714 carries an unsigned integer corresponding to the TSF time that the STA requests to wake up. The nominal minimum TWT wake-up duration field 1716 indicates the minimum amount of time that the TWT requesting STA or the TWT scheduled STA expects to remain in a wake-up state or mode. The TWT wake-up interval tail number field 1717 can be set to a non-zero value for periodic TWTs and a zero value for aperiodic TWTs. The broadcast TWT information field 1718 may include the broadcast TWT ID of the corresponding constrained TWT session and carry information indicating the number of TBTTs during which broadcast TWT SPs corresponding to the broadcast TWT parameter set exist.

[0134] Figure 17C Example structure of request type field 1720 is shown, based on some implementations of broadcast TWT parameter set fields that can be used for wireless communication. In some instances, request type field 1720 can be... Figure 17C An example of the request type field 1712. The request type field 1720 may include a TWT request subfield 1722, a TWT setup command subfield 1724, a trigger subfield 1726, a last broadcast parameter set subfield 1728, a stream type subfield 1730, a broadcast TWT recommendation subfield 1732, a TWT wake-up interval index subfield 1734, and several reserved bits 1736. The TWT request subfield 1722 may carry a value indicating whether the corresponding TWT information element was transmitted by the scheduled STA or the scheduling STA. The TWT setup command subfield 1724 may carry a value indicating the type of TWT command carried in the TWT information element. The trigger subfield 1726 may indicate whether the TWT SP indicated by TWT element 1700 includes a trigger frame or a frame carrying a TRS control subfield.

[0135] The Last Broadcast Parameter Set subfield 1728 indicates whether another broadcast TWT parameter set follows. For example, the Last Broadcast Parameter Set subfield 1728 can be set to a value of 0 to indicate that another TWT parameter set exists after this parameter set, or it can be set to a value of 1 to indicate that this is the last broadcast TWT parameter set in a broadcast TWT element. The Stream Type subfield 1730 indicates the type of interaction at the TWT between the TWT requester STA or the TWT scheduled STA and the TWT responder STA or the TWT scheduler AP. For example, setting the Stream Type subfield 1730 to a value of 0 indicates an advertised TWT in which the TWT requester STA or the TWT scheduled STA sends a PS polling or APSD trigger frame to signal its wake-up status. Setting the Stream Type subfield 1730 to a value of 1 indicates an unadvertised TWT in which the TWT responder STA or the TWT scheduler AP will send a frame to the TWT requester STA or the TWT scheduled STA without waiting to receive a PS polling or APSD trigger frame.

[0136] The Broadcast TWT Recommendation Subfield 1732 contains a value indicating a recommendation regarding the type of frame encoded according to the Broadcast TWT Recommendation Subfield 1732 used for broadcast TWT elements, transmitted by the TWT-scheduled STA and the scheduling AP during the Broadcast TWT SP. In some instances, the Broadcast TWT Recommendation Subfield 1732 may indicate whether the bound TWT session is a peer-to-peer TWT session or a broadcast TWT session. The TWT Wake-up Interval Index Subfield 1734 carries a value from which the TWT wake-up interval can be obtained. In some instances, the TWT Wake-up Interval Index Subfield 1734 is set to the exponent of the TWT wake-up interval value (in microseconds, base 2).

[0137] Figure 18 Example trigger frame 1800 is shown. Trigger frame 1800 can be used as a reference. Figure 7 or Figure 8 One or more of the described trigger frames. Trigger frame 1800 is shown as including a frame control field 1801, a duration field 1802, a receiver address (RA) field 1803, a sender address (TA) field 1804, a common information field 1805, several user information fields 1806(1)-1806(n), an optional padding field 1807, and a frame check sequence (FCS) field 1808. In some implementations, trigger frame 1800 may be a UL OFDMA trigger frame. In some other implementations, trigger frame 1800 may be a UL MU-MIMO mode trigger frame. Frame control field 1801 includes a type field and a subtype field (not shown for simplicity). Type field 1801A may store a value indicating that trigger frame 1800 is a control frame, and subtype field 1801B may store a value indicating the type of trigger frame 1800.

[0138] The duration field 1802 can store information indicating the duration or length of the trigger frame 1800. The RA field 1803 can store information about the receiving device (such as...). Figure 7 , 8 The address of one or more of the STAs in STAs 1, 19, or 20. TA field 1804 can store the address of the transmitting device (such as...). Figure 7 , 8 The address of the AP (AP 19 or 20). The shared information field 1805 may store information shared by one or more receiving devices. Each of the user information fields 1806(1)-1806(n) may store information about a specific receiving device, including, for example, the AID of that receiving device. The padding field 1807 may extend the length of the trigger frame 1800, for example, to give the receiving device additional time to generate a response. The FCS field 1808 may store a frame check sequence (such as for error detection).

[0139] Figure 19 A timing diagram depicting an example wireless communication 1900 supporting constrained TWT service periods according to some other implementations is shown. Figure 19 In the example, wireless communication 1900 can be performed between the AP, three wireless stations STA1-STA3, and one or more other STAs within the AP's communication range but not associated with the AP. The AP can be referenced separately. Figure 1 and 6A An example of AP 102 and AP 602 described. Each of the associated stations STA1, STA2, and STA3 can be referenced separately. Figure 1 and 6B An example of STA104 and STA 604 is described. Other non-associated STAs may also be referenced separately. Figure 1 and 6B Examples of STA 104 and 604 described.

[0140] exist Figure 19 Before the communication in the example begins at 1900, the AP can establish a constrained TWT session on the wireless channel. A constrained TWT session can include one or more constrained TWT service periods (SPs) during which the AP reserves the wireless channel for P2P communication between groups of STAs that are members of the constrained TWT session. For Figure 19 For example, stations STA1–STA3 are associated with the AP and are members of a constrained TWT session. In some respects, stations STA1–STA3 can be admitted as members of a constrained TWT session based on their association with the P2P link. Other STAs can be associated with the AP but not belong to a constrained TWT session. For simplicity, Figure 19 The example depicts only three stations STA1-STA3 belonging to a constrained TWT session. In some other implementations, a constrained TWT session can include more than... Figure 19 The examples described have fewer or more STAs.

[0141] In some instances, a group of stations STA1-STA3 belonging to a constrained TWT session can use one or more P2P links to exchange P2P data or communication with one or more other wireless communication devices (not shown for simplicity). The P2P link can be a direct link within a QoS BSS, a Tunneled Direct Link Establishment (TDLS) link, or STA-to-STA communication within a Independent Basic Service Set (IBSS). In some instances, each STA among stations STA1-STA3 can be a Tunneled Direct Link Establishment (TDLS) peering STA or a Wi-Fi peering (P2P) STA.

[0142] For reference Figure 7 As discussed, an AP can use TWT elements carried in beacon frames or other management frames (such as probe response frames, association response frames, and reassociation response frames) to announce a bounded TWT session. The TWT element can indicate the existence of a bounded TWT session, indicate that the bounded TWT session is associated with P2P communication or traffic, and indicate one or more parameters of the bounded TWT session. For example, these parameters can indicate the duration of each bounded TWTSP within the TWT session, the duration of the bounded TWT wake-up interval, the operating channel associated with the bounded TWT session, the target wake-up time of the bounded TWT session, and / or other operating parameters or capabilities associated with the bounded TWT session. These parameters can also indicate whether the bounded TWT session is a broadcast TWT session or an individual TWT session, and whether the bounded TWT session is a peer-to-peer TWT session.

[0143] In some instances, the TWT element may also include an indication for wireless communication devices that are not part of (or do not participate in) a constrained TWT session to terminate their corresponding TXOP and any associated transmissions on the wireless channel at or before the start of each constrained TWT SP in the TWT session. For example, a wireless communication device that is not a member of a constrained TWT session may decode a TWT element carried in one or more beacon frames transmitted from the AP and terminate its corresponding UL data transmission at or before time t0 based on the received indication. In some instances, the indication to terminate the TXOP before the start of each constrained TWT SP may be carried in the TWT parameter information field of the TWT element.

[0144] Before time t0, stations STA1-STA3 wake up from power saving (PS) mode or sleep state to listen for beacon frames and other management frames transmitted from the AP. Also before time t0, the AP can contend for channel access and acquire the TXOP on the radio channel. The AP becomes the owner of that TXOP on the radio channel during the TXOP's duration.

[0145] At time t0, which indicates the start of a constrained TWT SP, the AP transmits a guard frame P1 on the radio channel. Guard frame P1 identifies STA1 and STA2 to transmit or receive transmissions (such as P2P communication) during the TXOP acquired by the AP. STA3 is not identified by guard frame P1 and therefore does not participate in the constrained TWT SP (although STA3 may participate in one or more subsequent TWT SPs of the constrained TWT session). Guard frame P1 also protects the radio channel for transmissions to or from the STA identified by guard frame P1. In some implementations, guard frame P1 can protect transmissions to or from the identified stations STA1 and STA2 throughout the entire TXOP acquired by the AP. For example, guard frame P1 can indicate that the radio channel is busy or unavailable for receiving devices other than STA1 and STA2 during the entire TXOP. In some instances, guard frame P1 can instruct other receiving devices to set their corresponding Network Assignment Vector (NAV) to the duration of the TXOP acquired by the AP. Other receiving devices receive the protection frame P1, determine the NAV duration indicated in the protection frame P1, and then set the corresponding NAV of these other receiving devices to the TXOP duration obtained by the AP. In this way, the AP can use a single frame to protect transmissions to or from STA1 and STA2 (or other STAs identified by the protection frame P1) on the wireless channel for the entire TXOP duration.

[0146] In some other implementations, guard frame P1 can protect transmissions to or from the identified stations STA1 and STA2 for a period of time less than the TXOP duration (such as a portion or a percentage of the TXOP duration). For example, guard frame P1 can indicate that the radio channel is busy or unavailable to receiving devices other than the identified stations STA1 and STA2 for a period of time covering the transmission airtime of the first scheduling frame S1 plus the additional time duration. Figure 19 In the example, the transmission air time of the first scheduling frame S1 is denoted as T. S1 The transmission air time of the second scheduling frame S2 is denoted as T. S2 The additional time duration is represented as T. D Additional time duration T DIt can cover at least the initial portion of data transmission to or from a STA identified by a scheduled opportunity, and can ensure that the identified STA can access the radio channel to transmit or receive data during its respective scheduled opportunity. In some instances, the additional time duration T D This can be the duration of the Point Coordination Function (PCF) interframe interval (PIFS) or the duration of the Extended Interframe Interframe Interval (EIFS). In other instances, this additional time duration T D It can be the duration of the Short Interframe Spacing (SIFS) plus the expected response time of the corresponding STA. In some other instances, this additional time duration T D This could be an ACK timeout period. In this way, the guard frame P1 can protect the wireless channel at least during the initial portion of the transmission of P2P data 1910 by STA1.

[0147] Other receiving devices (such as wireless communication devices not belonging to a constrained TWT session) can receive guard frame P1, determine the NAV duration indicated by guard frame P1, and then set the corresponding NAV for these receiving devices to the indicated duration. In this way, the AP can protect the wireless channel for transmissions to or from STA1 and STA2 for any suitable time period less than the TXOP duration. In some instances, the AP can select at least one scheduled duration based on the amount of data to be transmitted to or from the respective STA.

[0148] In some implementations, the guard frame P1 can be a CTS or CTS-to-self frame, which includes a duration field set to the TXOP duration or the indicated time period. In some instances, the AP can set the RA field of the CTS or CTS-to-self frame to a configured MAC address that indicates the NAV duration for other receiving devices to avoid access or contention for access to the radio channel. The configured MAC address carried in the RA field of the CTS or CTS-to-self frame can also instruct the STAs identified by the guard frame P1 not to set their corresponding NAVs. In some other implementations, the guard frame P1 can be a trigger frame. The trigger frame can include the AID of the STAs (such as STA1 and STA2) identified by the guard frame P1 and can protect transmissions on the radio channel for the TXOP duration or the indicated time period. In some instances, the trigger frame can be a MU-RTS trigger frame. In other instances, the trigger frame can be a BSRP trigger frame, which can request reports of queued data (such as queued UL data or queued P2P data) from each STA (such as STA1 and STA2) identified by the guard frame P1.

[0149] Although for simplicity not included Figure 19As shown, however, each STA that receives the guard frame P1 can transmit a response frame to acknowledge receipt of the guard frame P1. The response frame can be an ACK frame, a CTS frame, or some other suitable frame that can acknowledge receipt of the first guard frame P1. In some instances, STA3 can return to a power-saving state or sleep mode at or before time t1.

[0150] At time t1, the AP transmits the first scheduling frame S1 on the wireless channel. In some instances, the first scheduling frame S1 can be a trigger frame, such as a MU-RTS trigger frame, a BSRP trigger frame, or a PS polling frame. In other instances, the first scheduling frame S1 can be a CTS frame or a CTS-to-itself frame. Figure 19 In the example, the first scheduling frame S1 identifies STA1 for a first scheduled opportunity and can schedule STA1 for P2P transmission on the radio channel during the first scheduled opportunity of the TXOP obtained by the AP. The first scheduling frame S1 can also instruct other receiving devices to set their respective NAVs to the duration of the first scheduled opportunity, a time period covering at least a portion of the transmission of radio packets by STA1, or some other suitable time duration. In some instances, the first scheduling frame S1 delivers a first TXOP token to STA1 within a first token period, and the NAV duration indicated by the first scheduling frame S1 covers the first token period plus the IFS duration (such as the PIFS duration or EIFS duration).

[0151] At time t2, STA1 transmits P2P data 1910 to another P2P STA (not shown for simplicity) on the wireless channel, at least in part, based on the first scheduling frame S1. In some implementations, the AP can facilitate a P2P link between STA1 and other P2P STAs. At time t3, the transmission of P2P data 1910 ends, which may also correspond to the end of the TXOP portion granted to STA1 by the AP. In some implementations, STA1 may receive an ACK frame from another P2P STA at time t4.

[0152] In some implementations, the AP can determine whether the duration of the NAV indicated by P2P transmission 1910 is less than the duration of the NAV indicated by the first scheduling frame S1. If the duration of the NAV indicated by P2P transmission 1910 is less than the duration of the NAV indicated by the first scheduling frame S1, the AP can schedule the transmission of the second scheduling frame S2 based on the end of the NAV duration indicated by P2P transmission 1910. Otherwise, the AP can schedule the transmission of the second scheduling frame S2 based on the end of the NAV duration indicated by the first scheduling frame S1.

[0153] In some implementations, if no data transmission occurs from STA1 during the first scheduling opportunity, the AP can ensure a certain level of channel utilization by restoring TXOP permission from STA1. For example, if the AP does not detect any data transmission from STA1 for a certain period of time, the AP can transmit a CF end frame on the radio channel. This CF end frame can terminate the first scheduling opportunity.

[0154] In some implementations, the AP can employ repetition and fault recovery. For example, if the AP does not detect any data transmission from STA1 within the initial time period of the first scheduled opportunity (this could indicate that the first scheduled frame S1 was not received by STA1, or that STA1 has no queued data to transmit), the AP can retransmit the first scheduled frame S1 to STA1. In some instances, the initial time period can be any suitable IFS duration. In other instances, the initial time period can be the AIFS duration plus the minimum contention window size (CW). min Alternatively, if the AP does not detect any data transmission from STA1 within the initial time period, the AP may transmit the second scheduling frame S2 to STA2. In some instances, the initial time period may be indicated by the first scheduling frame S1.

[0155] At time t5, the AP transmits a second scheduling frame S2 on the radio channel. In some instances, the second scheduling frame S2 can be a trigger frame, such as a MU-RTS trigger frame, a BSRP trigger frame, or a PS polling frame. In other instances, the second scheduling frame S2 can be a CTS frame or a CTS-to-self frame. The second scheduling frame S2 identifies STA2 and can schedule STA2 for P2P transmission on the radio channel during the second scheduling opportunity of the TXOP duration. The second scheduling frame S2 can also instruct other receiving devices to set their corresponding NAV to the duration of the second scheduling opportunity, a time period covering at least a portion of the transmission of radio packets by STA2, or some other suitable time duration. In some instances, the second scheduling frame S2 delivers a second TXOP token to STA2 within the second token period, and the NAV duration indicated by the second scheduling frame S2 covers the second token period plus the IFS duration (such as the PIFS duration or the EIFS duration).

[0156] At time t6, STA2 transmits P2P data 1920 to another P2P STA (not shown for simplicity) on the wireless channel, at least in part, based on the second scheduling frame S2. In some implementations, the AP can facilitate a P2P link between STA2 and this other P2P STA. At time t7, the transmission of P2P data 1920 ends, which may also correspond to the end of the TXOP portion granted to STA2 by the AP. In some implementations, STA2 may receive an ACK frame from this other P2P STA at time t8.

[0157] At time t9, the AP can transmit a third scheduling frame S3 on the radio channel to request UL transmission during the corresponding third scheduling opportunity, etc., until the constrained TWT SP at time t9. 12 The end. Figure 19 In the example, the AP may not have any queued downlink data for any of STAs 1-3, and none of the STAs identified by the third scheduling frame S3 may have queued uplink data available for transmission to the AP during the third scheduling opportunity. In some implementations, the AP can monitor the radio channel and detect the absence of data transmission on the radio channel during the third scheduling opportunity. In some instances, the AP can restore the remainder of the TXOP granted to the STA(s) identified by the third scheduling frame S3 and can allow other STAs to access the radio channel. Figure 19 In the example, another STA uses a contention-based channel access mechanism (such as EDCA) at time t. 10 Gain access to the wireless channel, and at time t 10 With t 11 It transmits or receives one or more PPDU 1930s over a wireless channel. At time t 13 The constrained TWT session ends.

[0158] Figure 20 A timing diagram is shown depicting another example of a wireless communication 2000 that supports constrained TWT sessions for P2P communication according to some implementations. Figure 20 In the example, Wireless Communication 2000 can be referenced. Figure 19 The described process is performed between the AP and each STA. Figure 20 The timing diagram is similar in many ways to Figure 19 The timing diagram, and in some ways different Figure 19 The timing diagram. Specifically, when participating... Figure 19 In Example Communication 1900, stations STA1 and STA2 participate in transmitting P2P data to one or more other wireless communication devices during the first and second corresponding scheduled opportunities. Figure 20In Example Communication 2000, stations STA1 and STA2 receive P2P data from one or more other wireless communication devices during the first and second corresponding scheduled opportunities.

[0159] Figure 21 A flowchart illustrating an example process 2100 for supporting constrained TWT service periods for P2P communication, according to some implementation, is shown. Process 2100 can be implemented by a wireless communication device (such as referenced...) Figure 5 The wireless communication device 500 described herein may be used to perform the process. In some implementations, process 2100 may be performed by an AP (such as referred to separately). Figure 1 and Figure 6A The wireless communication device that operates or operates within the AP (either of the described APs 102 and 602) performs this function.

[0160] For example, in block 2102, the AP establishes a constrained target wake-up time (TWT) session on the wireless channel, the constrained TWT session including at least one constrained TWT service period (SP) for P2P communication. In block 2104, the AP admits a group of radio stations (STAs) associated with the P2P communication as members of the constrained TWT session. In block 2106, the AP obtains a transmission opportunity (TXOP) on the wireless channel during the at least one constrained TWT SP. In block 2108, the AP transmits a guard frame on the wireless channel, the guard frame identifying one or more STAs belonging to the constrained TWT session that are permitted to transmit or receive P2P communication on the wireless channel during the TXOP. The guard frame may also indicate to receiving devices other than the identified one or more STAs that the wireless channel is unavailable for at least a portion of the TXOP. In some instances, each STA in the STA group may be a Tunneled Direct Link Establishment (TDLS) peering STA or a Wi-Fi peering (P2P) STA.

[0161] In some implementations, the one or more STAs identified by the guard frame include fewer STAs than all STAs belonging to the constrained TWT session. That is, in some instances, the guard frame may identify a subset of the STA group belonging to the constrained TWT session and may only allow those STAs identified by the guard frame to contend for channel access and obtain TXOP on the radio channel. In this way, the AP can manage or limit the number of STAs attempting to access the radio channel at any given time, thereby reducing the likelihood of collisions on the radio channel and increasing the probability of the respective STA obtaining access to the radio channel.

[0162] In some implementations, the guard frame can indicate that the radio channel is busy or unavailable to receiving devices other than the one or more selected STAs throughout the TXOP. For example, in some instances, the guard frame can instruct other receiving devices to set their respective NAVs to the TXOP duration.

[0163] In some other implementations, the guard frame may indicate that the radio channel is busy or unavailable to receiver devices other than one or more selected STAs for a period of time less than the TXOP duration. For example, the guard frame may instruct other receiver devices to set their respective NAVs to the indicated time period. The indicated time period may cover the transmission airtime of the first scheduling frame plus an additional time duration. This additional time duration may cover at least the initial portion of data transmission to or from the STA identified or scheduled by the scheduling opportunity, and may ensure that the identified or scheduled STA can access the radio channel to transmit or receive data during their respective scheduling opportunity. In some instances, the additional time duration may be the Point Coordination Function (PCF) Interframe Spacing (PIFS) duration or the Extended Interframe Spacing (EIFS) duration. In other instances, the additional time duration may be the Short Interframe Spacing (SIFS) duration plus the expected response time of the corresponding STA. In some other instances, the additional time duration may be the Acknowledgment (ACK) timeout period.

[0164] In some implementations, the guard frame may be a CTS frame or a CTS-to-self frame, instructing other receiving devices to set their corresponding NAV to a period shorter than the TXOP. In some aspects, the CTS frame or CTS-to-self frame includes a duration field set to the time period. In some instances, the Receiver Address (RA) field of the CTS frame or CTS-to-self frame may be set to a predefined MAC address to indicate that one or more identified STAs are permitted access to the radio channel during the TXOP. In other instances, the RA field of the CTS frame or CTS-to-self frame may be set to the MAC address of the identified STA.

[0165] In some other implementations, the protection frame can be a trigger frame, which includes the AID of the identified STA and a duration field set to the duration of the TXOP or the indicated time period. In some instances, the trigger frame can be a MU-RTS trigger frame. In other instances, the trigger frame can be a BSRP trigger frame. In still other instances, the trigger frame can be a CF polling frame. Figure 22 A flowchart illustrating another example process 2200 for supporting constrained TWT service periods for P2P communication, according to some implementation, is shown. Process 2200 can be implemented by a wireless communication device (such as referenced...) Figure 5The wireless communication device 500 described herein may be used to perform the process. In some implementations, process 2200 may be performed by an AP (such as referred to separately). Figure 1 and Figure 6A The wireless communication device that operates or operates within the AP (either of the described APs 102 and 602) performs the procedure. In some instances, procedure 2200 may be performed by... Figure 21 The transmission of the guard frame in block 2108 of process 2100 is performed afterward. For example, in block 2202, the AP transmits one or more scheduling frames on the wireless channel during the TXOP, each scheduling frame being configured to schedule the corresponding STA identified by the guard frame for P2P transmission on the wireless channel during the corresponding scheduling opportunity period within the TXOP.

[0166] In some implementations, the scheduling frame may be a CTS frame or a CTS-to-self frame, which includes a duration field set to the duration of the corresponding scheduled opportunity. In some instances, the RA field of the CTS frame or CTS-to-self frame may be set to the MAC address of the STA identified or scheduled by the corresponding scheduled opportunity. The CTS frame or CTS-to-self frame may pass a TXOP token to the identified STA and may include an indication of the TXOP token. The CTS frame or CTS-to-self frame may also include an indication that the CTS frame or CTS-to-self frame is a scheduling frame.

[0167] In other implementations, the scheduling frame may be a trigger frame that includes an AID for each STA identified or scheduled for the corresponding scheduled opportunity. In some instances, the trigger frame may be a MU-RTS trigger frame that includes one or more per-user information fields indicating the allowed duration of P2P transmissions from one or more corresponding STAs during the corresponding scheduled opportunity. In some other instances, the trigger frame may be a BSRP trigger frame that includes one or more per-user information fields indicating the allowed duration of P2P transmissions from one or more corresponding STAs during the corresponding scheduled opportunity. In some other instances, each per-user information field carried in the MU-RTS or BSRP trigger frame may indicate the amount of time the corresponding STA should delay accessing the radio channel during the corresponding scheduled opportunity.

[0168] In some other implementations, at least one scheduling frame can be a Quality of Service (QoS) data frame or a QoS empty frame. In some instances, the QoS data frame can be a Contention-Free Polling (CF Polling) frame. A CF Polling frame may include a TXOP limit subfield, which instructs the corresponding STA among the selected STAs to transmit only one data frame or one QoS empty frame after receiving the CF Polling frame. In some implementations, each scheduling frame may instruct other receiving devices to set their corresponding NAV to the duration of the corresponding scheduled opportunity. In this way, the AP can facilitate P2P transmission between the STA identified by the scheduling frame and another wireless communication device during the corresponding scheduled opportunity. In some instances, the NAV duration indicated by the scheduling frame covers the token period plus the inter-frame interval (IFS) duration. The IFS duration can be a PIFS duration or an EIFS duration. The scheduling frame can be configured to identify a first STA among one or more STAs identified by the guard frame for transmitting P2P data on the wireless channel during the corresponding scheduled opportunity. In some instances, the scheduling frame delivers a TXOP token to the first STA during the token period. Additionally or alternatively, the NAV duration indicated by the last scheduling frame may cover the last token cycle of the TXOP.

[0169] In some implementations, the respective STAs can use a Listen-Before-Speak (LBT) channel access mechanism to access the radio channel during the corresponding scheduled opportunity period. In some instances, the LBT channel access mechanism can be a Clear Channel Assessment (CCA) without backoff procedures, which allows each STA to be granted a portion of the scheduled opportunity period for TXOP to access the radio channel faster than a channel access mechanism that includes backoff procedures.

[0170] Figure 23 A flowchart illustrating another example process 2300 for supporting wireless communication with a constrained TWT service period for P2P communication, according to some implementation, is shown. Process 2300 can be implemented by a wireless communication device (such as referenced in the diagram). Figure 5 The wireless communication device 500 described herein may be used to perform the process. In some implementations, the process 2300 may be performed by an AP (such as referred to separately). Figure 1 and Figure 6A The wireless communication device that operates or operates within the AP (either of the described APs 102 and 602) performs this function.

[0171] In some instances, process 2300 can Figure 22The process 2200 is performed after the transmission of one or more scheduling frames in block 2202. For example, in block 2302, the AP receives a request for a scheduled resource from at least one of the identified STAs during the at least one constrained TWT SP. In block 2304, the AP transmits a scheduling frame for the at least one identified STA based on the received request.

[0172] Figure 24 A flowchart illustrating another example process 2400 for supporting wireless communication with a constrained TWT service period for P2P communication, according to some implementation, is shown. Process 2400 can be implemented by a wireless communication device (such as referenced in the diagram). Figure 5 The wireless communication device 500 described herein may be used to perform the process. In some implementations, the process 2400 may be performed by an AP (such as referred to separately). Figure 1 and Figure 6A The wireless communication device that operates or operates within the AP (either of the described APs 102 and 602) performs this function.

[0173] In some instances, process 2400 can Figure 22 The process in block 2202 of 2200 is performed between the transmissions of the one or more scheduled frames. For example, in block 2402, the AP listens for the radio channel during the corresponding scheduled opportunity. In block 2404, the AP resumes the TXOP from the corresponding STA based on the detection that no P2P transmission occurred during the corresponding scheduled opportunity. In some instances, the AP may transmit a CF end frame to resume the remainder of the TXOP portion.

[0174] Figure 25 A flowchart illustrating another example process 2500 for supporting wireless communication with a constrained TWT service period for P2P communication, according to some implementation, is shown. Process 2500 can be implemented by a wireless communication device (such as referenced...) Figure 5 The wireless communication device 2500 described herein may be used to perform the process. In some implementations, the process 2500 may be performed by an AP (such as referred to separately). Figure 1 and Figure 6A The wireless communication device that operates or operates within the AP (either of the described APs 102 and 602) performs this function.

[0175] In some instances, process 2500 can be Figure 22The process 2200 is executed after one of the transmission scheduling frames in block 2202. For example, in block 2502, the AP receives a frame from one or more of the identified STAs based on the corresponding scheduling frame. In block 2504, the AP determines whether the duration of the NAV included in the received frame is less than the NAV duration indicated by the corresponding scheduling frame. In block 2506, the AP schedules the transmission of the next scheduling frame in the one or more scheduling frames in response to determining that the NAV duration included in the received frame is less than the NAV duration indicated by the corresponding scheduling frame. In some implementations, the timing of the transmission of the next scheduling frame may be based on the end of the NAV duration included in the received frame (e.g., not at the end of the NAV duration indicated by the corresponding scheduling frame). In this way, the AP can increase media utilization by adjusting the duration of the scheduling opportunity based on the data transmission to or from the STA identified or scheduled by the scheduling opportunity.

[0176] Figure 26 A flowchart illustrating another example process 2600 for supporting constrained TWT service periods for P2P communication, according to some implementation, is shown. Process 2600 can be implemented by a wireless communication device (such as referenced...) Figure 5 The wireless communication device 500 described herein may perform the procedure. In some implementations, the procedure 2600 may be performed by an AP (such as referred to separately). Figure 1 and Figure 6A The wireless communication device that operates or operates within the AP (either of the described APs 102 and 602) performs this function.

[0177] In some instances, process 2600 can Figure 21 The process 2100 is performed after the transmission guard frame in block 2108. For example, in block 2602, the AP determines that at least two of the identified STAs are associated with the P2P link. In block 2604, the AP allocates time or frequency resources to the at least two STAs during at least a portion of the constrained TWT SP. In some instances, the P2P link may be a Tunneling Direct Link Establishment (TDLS) link over the radio channel.

[0178] Figure 27 A block diagram of an example wireless communication device 2700 according to some implementations is shown. In some implementations, the wireless communication device 2700 is configured to perform reference... Figure 21-26 One or more of the processes described. In some implementations, the wireless communication device 2700 may be a reference. Figure 5An example implementation of the described wireless communication device 500. For example, the wireless communication device 2700 may be a chip, SoC, chipset, package, or device that includes at least one processor and at least one modem (e.g., a Wi-Fi (IEEE 802.11) modem or a cellular modem).

[0179] Wireless communication device 2700 includes a receiving component 2710, a communication manager 2720, and a transmitting component 2730. The communication manager 2720 may further include a constrained TWT session establishment component 2722, a TWT scheduling component 2724, and a TXOP component 2726. A portion of one or more of components 2722, 2724, and 2726 may be implemented at least partially in hardware or firmware. In some implementations, at least one of components 2722, 2724, or 2726 is implemented at least partially as software stored in memory (such as memory 508). For example, a portion of one or more of components 2722, 2724, and 2726 may be implemented as non-transient instructions or code executable by a processor (such as processor 506) to perform the function or operation of the respective component.

[0180] Receiving component 2710 is configured to receive RX signals from other wireless communication devices. In some implementations, the RX signal may include UL data from one or more STAs belonging to a constrained TWT session established by wireless communication device 2700. In some implementations, constrained TWT session establishment component 2722 may establish a constrained TWT session that includes at least one constrained TWT SP during which the AP reserves a wireless channel for P2P communication. Constrained TWT session establishment component 2722 may also admit a group of STAs associated with P2P communication as members of the constrained TWT session. TWT scheduling component 2724 may schedule UL transmissions from one or more STAs belonging to the constrained TWT session and DL transmissions to or from those one or more STAs. TXOP component 2726 may contend for channel access and obtain a TXOP during one or more TWT SPs associated with the constrained TWT session. Transmitting component 2730 is configured to transmit TX signals to other wireless communication devices. In some implementations, the TX signal may include a guard frame, a trigger frame, and a scheduling frame.

[0181] Examples of implementations are described in the following numbered clauses.

[0182] 1. A method for wireless communication by a wireless communication device operating as an access point (AP).

[0183] The methods include:

[0184] Establish a constrained target wake-up time (TWT) session on the wireless channel, the constrained TWT

[0185] The session includes at least one constrained TWT service period (SP) for peer-to-peer (P2P) communication;

[0186] Accept the group of radio stations (STAs) associated with P2P communication as the constrained TWT session.

[0187] Members;

[0188] Obtaining transmission opportunities on the wireless channel during at least one constrained TWT SP

[0189] (TXOP); and

[0190] A guard frame is transmitted on the wireless channel, the guard frame identifying that it belongs to the constrained TWT session.

[0191] The STA group is permitted to transmit or receive P2P communications on the radio channel during the TXOP period.

[0192] The protection frame is sent to one or more STAs other than the one or more identified STAs.

[0193] The device indicates that the wireless channel is unavailable within at least a portion of the TXOP.

[0194] 2. As in Clause 1, wherein the one or more identified STAs include those belonging to the

[0195] The number of STAs in the constrained TWT session is less than the number of STAs in the STA group.

[0196] 3. The methods described in Clause 1 or 2, further including:

[0197] Determine that at least two of the identified STAs are associated with a P2P link; and

[0198] Time or frequency is allocated to the at least two STAs during at least a portion of the TXOP period.

[0199] resource.

[0200] 4. The method of any or more of the provisions 1-3, wherein the P2P link includes a Tunneling Direct Link Establishment (TDLS) link over the radio channel.

[0201] 5. The method of any or more of Clauses 1-4, wherein the protection frame includes a Clear Transmit (CTS) frame or a CTS to Self frame that instructs other receiving devices to set their respective Network Allocation Vectors (NAVs) to a time period less than the TXOP.

[0202] 6. The method of Clause 5, wherein the time period encompasses the airtime of the scheduling frame transmitted by the AP plus one of the following: the duration of the Point Coordination Function (PCF) Inter-Frame Interval (PIFS), the duration of the Extended Inter-Frame Interval (EIFS), or the Acknowledgment (ACK) timeout period.

[0203] 7. The method of any or more of Clauses 1-6, wherein the guard frame indicates that, based on the receipt of the guard frame, each STA in the STA group belonging to the constrained TWT session and not identified by the guard frame shall enter power saving (PS) mode.

[0204] 8. The method of Clause 7, wherein the guard frame indicates the period during which each STA in the STA group belonging to the constrained TWT session and not identified by the guard frame remains in the PS mode.

[0205] 9. The method of any or more of the provisions 1-8, wherein the protection frame includes a trigger frame that includes an association identifier (AID) for each of the one or more identified STAs.

[0206] 10. The methods of any or more of Clauses 1-9 further include:

[0207] During the TXOP, one or more scheduling frames are transmitted on the wireless channel, each scheduling frame being configured to schedule the corresponding STA identified by the guard frame for P2P transmission on the wireless channel during the corresponding scheduling opportunity period within the TXOP.

[0208] 11. The method of Clause 10, wherein each scheduling frame indicates that receiving devices other than the corresponding STA should set their corresponding network allocation vector (NAV) to the duration of the corresponding scheduled opportunity.

[0209] 12. The method of Clause 10 or 11, wherein each scheduling frame includes a trigger frame that includes a per-user information field indicating the transmission scheduling of the corresponding STA, and wherein the per-user information field further indicates the allowed duration of the P2P transmission to or from the corresponding STA.

[0210] 13. The methods of any or more of clauses 10-12 further include:

[0211] During the at least one constrained TWT SP, a request for a scheduled resource is received from at least one of the identified STAs; and

[0212] Based on the received request, a scheduling frame for the at least one identified STA is transmitted.

[0213] 14. The methods of any or more of clauses 10-12, further comprising:

[0214] Listening to the radio channel during the corresponding scheduled opportunity; and

[0215] The TXOP is restored from the corresponding STA based on the detection that no P2P transmission is detected during the corresponding scheduled opportunity.

[0216] 15. The methods of any or more of clauses 10-14, further comprising:

[0217] Frames are received from one or more of the STAs identified by the protection frame based on the corresponding scheduling frame;

[0218] Determine whether the duration of the Network Allocation Vector (NAV) included in the received frame is less than the NAV duration indicated by the corresponding scheduling frame; and

[0219] In response to determining that the NAV duration included in a received frame is less than the NAV duration indicated by the corresponding scheduling frame, the transmission of the next scheduling frame in one or more scheduling frames is scheduled.

[0220] 16. The method of Clause 15, wherein the timing of the transmission of the next scheduled frame is based on the end of the NAV duration included in the received frame.

[0221] 17. A wireless communication device, comprising:

[0222] At least one modem;

[0223] At least one processor, the at least one processor being communicatively coupled to the at least one modem; and

[0224] At least one memory, communicatively coupled to and storing processor-readable code, which is configured to, when executed by the at least one processor in conjunction with the at least one modem:

[0225] Establish a constrained target wake-up time (TWT) session on a wireless channel, the constrained TWT session including at least one constrained TWT service period (SP) for peer-to-peer (P2P) communication;

[0226] Accept the group of radio stations (STAs) associated with P2P communication as members of the constrained TWT session;

[0227] To obtain a transmission opportunity (TXOP) on the wireless channel during at least one constrained TWT SP; and

[0228] A guard frame is transmitted on the wireless channel, which identifies one or more STAs belonging to the constrained TWT session who are permitted to transmit or receive P2P communication on the wireless channel during the TXOP. The guard frame indicates to receiving devices other than the identified one or more STAs that the wireless channel is unavailable for at least a portion of the TXOP.

[0229] 18. A wireless communication device as described in Clause 17, wherein the one or more identified STAs comprise fewer STAs than all STAs in the group of STAs belonging to the constrained TWT session.

[0230] 19. A wireless communication device as described in Clause 17 or 18, wherein the execution of the processor-readable code is further configured to:

[0231] Determine that at least two of the identified STAs are associated with a P2P link; and

[0232] During at least a portion of the TXOP, time or frequency resources are allocated to the at least two STAs.

[0233] 20. A wireless communication device as described in Clause 19, wherein the P2P link includes a Tunneling Direct Link Establishment (TDLS) link over the wireless channel.

[0234] 21. A wireless communication device as described in Clause 17, wherein the guard frame includes a Clear Transmit (CTS) frame or a CTS to Self frame that instructs other receiving devices to set their respective Network Allocation Vectors (NAVs) to a period less than the TXOP.

[0235] 22. A wireless communication device of any or more of the provisions 17-21, wherein the guard frame indicates that, based on the receipt of the guard frame, each STA in the STA group belonging to the constrained TWT session and not identified by the guard frame shall enter a power saving (PS) mode.

[0236] 23. A wireless communication device as described in Clause 22, wherein the guard frame indicates the period during which each STA in the group of STAs belonging to the constrained TWT session and not identified by the guard frame remains in the PS mode.

[0237] 24. A wireless communication device of any or more of the terms 17-23, wherein the execution of the processor-readable code is further configured to:

[0238] During the TXOP, one or more scheduling frames are transmitted on the wireless channel, each scheduling frame being configured to schedule the corresponding STA identified by the guard frame for P2P transmission on the wireless channel during the corresponding scheduling opportunity period within the TXOP.

[0239] 25. A wireless communication device as described in Clause 24, wherein each scheduling frame indicates that receiver devices other than the corresponding STA should set their corresponding network allocation vector (NAV) for the duration of the corresponding scheduled opportunity.

[0240] 26. A wireless communication device of any or more of the provisions of 24-25, wherein each scheduling frame includes a trigger frame that includes a per-user information field indicating the transmission scheduling of the corresponding STA.

[0241] 27. A wireless communication device as described in Clause 26, wherein the per-user information field further indicates the permitted duration of a P2P transmission to or from the corresponding STA.

[0242] 28. A wireless communication device of any or more of the terms 24-27, wherein the execution of the processor-readable code is further configured to:

[0243] During at least one constrained TWT SP, from at least one of the identified STAs

[0244] The STA receives requests for scheduled resources; and

[0245] Based on the received request, a scheduling frame for at least one identified STA is transmitted.

[0246] 29. A wireless communication device of any or more of the terms 24-28, wherein the processor

[0247] The execution of readable code is further configured as follows:

[0248] Listening to the radio channel during the corresponding scheduled opportunity; and

[0249] Based on the detection that no P2P transmission was detected during the corresponding scheduled opportunity, from that corresponding

[0250] STA restores the TXOP.

[0251] 30. A wireless communication device of any or more of the terms 24-29, wherein the processor

[0252] The execution of readable code is further configured as follows:

[0253] Frames are received from one or more of the STAs identified by the protection frame based on the corresponding scheduling frame;

[0254] The time required to determine whether the network allocation vector (NAV) included in the received frames is small

[0255] During the NAV duration indicated by the corresponding scheduling frame; and

[0256] In response to determining that the duration of the NAV included in the received frame is less than that of the corresponding scheduler

[0257] The transmission of the next scheduled frame in one or more scheduled frames is scheduled based on the NAV duration indicated by the frame.

[0258] As used herein, the phrase “at least one of” or “one or more of” referring to a list of items means any combination of these items, including a single member. For example, “at least one of a, b, or c” is intended to cover the following possibilities: only a, only b, only c, a combination of a and b, a combination of a and c, a combination of b and c, and a combination of a, b, and c.

[0259] The various illustrative components, logic, logic blocks, modules, circuits, operations, and algorithmic processes described in conjunction with the implementations disclosed herein can be implemented as electronic hardware, firmware, software, or a combination of hardware, firmware, or software, including the structures disclosed in this specification and their structural equivalents. This interchangeability of hardware, firmware, and software has been generally described in terms of its functionality and is illustrated in the various illustrative components, blocks, modules, circuits, and processes described above. Whether such functionality is implemented in hardware, firmware, or software depends on the specific application and the design constraints imposed on the overall system.

[0260] Various modifications to the implementations described in this disclosure may be apparent to those skilled in the art, and the general principles defined herein may be applied to other implementations without departing from the spirit or scope of this disclosure. Therefore, the claims are not intended to be limited to the implementations shown herein, but are to be granted the broadest scope consistent with this disclosure, the principles disclosed herein, and the novel features.

[0261] Furthermore, the various features described in this specification in the context of separate implementations may also be implemented in combination in a single implementation. Conversely, the various features described in the context of a single implementation may also be implemented separately or in any suitable sub-combination in multiple implementations. Thus, although features may be described above as operating in a particular combination and even initially claimed in this way, one or more features from the claimed combination may be removed from that combination in some cases, and the claimed combination may be for sub-combinations or variations thereof.

[0262] Similarly, although the operations are depicted in a specific order in the accompanying drawings, this should not be construed as requiring such operations to be performed in the specific order shown or sequentially, or requiring the execution of all explained operations to achieve the desired result. Furthermore, the drawings may schematically depict one or more example processes in the form of flowcharts or flow diagrams. However, other operations not depicted may be incorporated into the schematically explained example processes. For example, one or more additional operations may be performed before, after, simultaneously with, or between any explained operations. In some environments, multitasking and parallel processing may be advantageous. Moreover, the separation of the various system components in the implementation described above should not be construed as requiring such separation in all implementations, and it should be understood that the described program components and systems can generally be integrated together in a single software product or packaged into multiple software products.

Claims

1. A method for wireless communication by a wireless communication device operating as an access point (AP), comprising: Establish a constrained target wake-up time (TWT) session on a wireless channel, the constrained TWT session including at least one constrained TWT service period (SP) for peer-to-peer (P2P) communication; Accept the group of radio stations (STAs) associated with P2P communication as members of the constrained TWT session; Obtain a transmission opportunity (TXOP) on the wireless channel during the at least one constrained TWT SP; as well as A guard frame is transmitted on the wireless channel, the guard frame identifying one or more STAs belonging to the constrained TWT session who are permitted to transmit or receive P2P communication on the wireless channel during the TXOP, the guard frame indicating to devices other than the one or more identified STAs that the wireless channel is unavailable for at least a portion of the TXOP.

2. The method as described in claim 1, wherein, The one or more identified STAs include fewer STAs than all STAs in the STA group belonging to the constrained TWT session.

3. The method of claim 1, further comprising: Determine that at least two of the identified STAs are associated with a P2P link; as well as During at least a portion of the TXOP, time or frequency resources are allocated to the at least two STAs.

4. The method of claim 3, wherein, The P2P link includes a Tunnel Direct Link Establishment (TDLS) link on the wireless channel.

5. The method of claim 1, wherein, The protection frame includes a Clear Transmit (CTS) frame or a CTS to Self frame, which instructs other receiving devices to set their corresponding Network Allocation Vector (NAV) to a time period less than the TXOP.

6. The method of claim 5, wherein, The time period encompasses the airtime of the scheduling frame transmitted by the AP plus one of the following: the duration of the Point Coordination Function (PCF) Inter-Frame Interval (PIFS), the duration of the Extended Inter-Frame Interval (EIFS), or the Acknowledgment (ACK) timeout period.

7. The method of claim 1, wherein, The protection frame indicates that, based on the receipt of the protection frame, each STA in the STA group that belongs to the constrained TWT session and is not identified by the protection frame should enter a power saving (PS) mode.

8. The method of claim 7, wherein, The protection frame indicates the time period during which each STA in the STA group that belongs to the constrained TWT session and is not identified by the protection frame remains in the PS mode.

9. The method of claim 1, wherein, The protection frame includes a trigger frame, which includes an association identifier (AID) for each of the one or more identified STAs.

10. The method of claim 1, further comprising: During the TXOP, one or more scheduling frames are transmitted on the wireless channel, each scheduling frame being configured to schedule a corresponding STA identified by the guard frame for P2P transmission on the wireless channel during a corresponding scheduling opportunity within the TXOP.

11. The method of claim 10, wherein each scheduling frame indicates that the receiving devices other than the corresponding STA should set their respective network allocation vectors (NAVs) for the duration of the corresponding scheduled opportunity.

12. The method of claim 10, wherein, Each scheduling frame includes a trigger frame, which includes a per-user information field indicating the transmission scheduling of the corresponding STA, and wherein the per-user information field further indicates the allowed duration of P2P transmissions to or from the corresponding STA.

13. The method of claim 10, further comprising: During the at least one constrained TWT SP, a request for a scheduled resource is received from at least one of the identified STAs. as well as Based on the received request, a scheduling frame for the at least one identified STA is transmitted.

14. The method of claim 10, further comprising: Listen to the wireless channel during the corresponding scheduled opportunity; as well as The TXOP is restored from the corresponding STA based on the detection that no P2P transmission is detected during the corresponding scheduled opportunity.

15. The method of claim 10, further comprising: Frames are received from one or more of the STAs identified by the protection frame based on the corresponding scheduling frame; Determine whether the duration of the network allocation vector (NAV) included in the received frame is less than the NAV duration indicated by the corresponding scheduling frame; as well as In response to determining that the NAV duration included in a received frame is less than the NAV duration indicated by the corresponding scheduling frame, the transmission of the next scheduling frame in one or more scheduling frames is scheduled.

16. The method of claim 15, wherein, The timing of the transmission of the next scheduled frame is based on the end of the NAV duration included in the received frame.

17. A wireless communication device, comprising: At least one modem; At least one processor, the at least one processor being communicatively coupled to the at least one modem; as well as At least one memory, communicatively coupled to and storing processor-readable code, the processor-readable code being configured, when executed by the at least one processor in conjunction with the at least one modem, to: Establish a constrained target wake-up time (TWT) session on a wireless channel, the constrained TWT session including at least one constrained TWT service period (SP) for peer-to-peer (P2P) communication; Accept the group of radio stations (STAs) associated with P2P communication as members of the constrained TWT session; Obtain a transmission opportunity (TXOP) on the wireless channel during the at least one constrained TWT SP; as well as A guard frame is transmitted on the wireless channel, the guard frame identifying one or more STAs belonging to the constrained TWT session who are permitted to transmit or receive P2P communication on the wireless channel during the TXOP, the guard frame indicating to receiving devices other than the identified one or more STAs that the wireless channel is unavailable for at least a portion of the TXOP.

18. The wireless communication device as claimed in claim 17, wherein, The one or more identified STAs include fewer STAs than all STAs in the STA group belonging to the constrained TWT session.

19. The wireless communication device of claim 17, wherein execution of the processor-readable code is further configured to: Determine that at least two of the identified STAs are associated with a P2P link; and During at least a portion of the TXOP, time or frequency resources are allocated to the at least two STAs.

20. The wireless communication device as claimed in claim 19, wherein, The P2P link includes a Tunnel Direct Link Establishment (TDLS) link on the wireless channel.

21. The wireless communication device as claimed in claim 17, wherein, The protection frame includes a Clear Transmit (CTS) frame or a CTS to Self frame, which instructs other receiving devices to set their corresponding Network Allocation Vector (NAV) to a time period less than the TXOP.

22. The wireless communication device as claimed in claim 17, wherein, The protection frame indicates that, based on the receipt of the protection frame, each STA in the STA group that belongs to the constrained TWT session and is not identified by the protection frame should enter a power saving (PS) mode.

23. The wireless communication device as claimed in claim 22, wherein, The protection frame indicates the time period during which each STA in the STA group that belongs to the constrained TWT session and is not identified by the protection frame remains in the PS mode.

24. The wireless communication device of claim 17, wherein execution of the processor-readable code is further configured to: During the TXOP, one or more scheduling frames are transmitted on the wireless channel, each scheduling frame being configured to schedule a corresponding STA identified by the guard frame for P2P transmission on the wireless channel during a corresponding scheduling opportunity within the TXOP.

25. The wireless communication device as claimed in claim 24, wherein, Each scheduling frame instructs receiving devices other than the corresponding STA to set their respective Network Allocation Vector (NAV) to the duration of the corresponding scheduled opportunity.

26. The wireless communication device of claim 24, wherein each scheduling frame includes a trigger frame, the trigger frame including a per-user information field indicating the transmission scheduling of the corresponding STA.

27. The wireless communication device as claimed in claim 26, wherein, The per-user information field further indicates the allowed duration of P2P transmissions to or from the corresponding STA.

28. The wireless communication device of claim 24, wherein execution of the processor-readable code is further configured to: During the at least one constrained TWT SP, a request for scheduled resources is received from at least one of the identified STAs; and Based on the received request, a scheduling frame for the at least one identified STA is transmitted.

29. The wireless communication device of claim 24, wherein execution of the processor-readable code is further configured to: Listening to the wireless channel during the corresponding scheduled opportunity; and The TXOP is restored from the corresponding STA based on the detection that no P2P transmission is detected during the corresponding scheduled opportunity.

30. The wireless communication device of claim 24, wherein execution of the processor-readable code is further configured to: Frames are received from one or more of the STAs identified by the protection frame based on the corresponding scheduling frame; Determine whether the duration of the Network Allocation Vector (NAV) included in the received frame is less than the NAV duration indicated by the corresponding scheduling frame; and In response to determining that the NAV duration included in a received frame is less than the NAV duration indicated by the corresponding scheduling frame, the transmission of the next scheduling frame in one or more scheduling frames is scheduled.

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