WO2021162945A1

WO2021162945A1 - Power saving mechanisms for software enabled access point (softap)

Info

Publication number: WO2021162945A1
Application number: PCT/US2021/016750
Authority: WO
Inventors: Imran ANSARI; Harbeer SINGH; Rajeev Kumar Singh
Original assignee: Qualcomm Incorporated
Priority date: 2020-02-13
Filing date: 2021-02-05
Publication date: 2021-08-19

Abstract

This disclosure provides methods, devices and systems for reducing power consumption in wireless communication devices operating on the 6 GHz frequency band. In some implementations, a wireless communication device broadcasts a beacon frame signaling the start of a beacon interval and determines a power management (PM) mode of each wireless station (STA) associated with the wireless communication device during the beacon interval. The wireless communication device further broadcasts a number of fast initial link setup (FILS) discovery frames during the beacon interval, where the number of FILS discovery frames is based at least in part on the PM modes of the associated STAs. In some implementations, the wireless communication device may broadcast a single FILS discovery frame responsive to determining that each of the associated STAs is in a sleep state. The wireless communication device may subsequently operate in a power save mode for the remainder of the beacon interval.

Description

POWER SAVING MECHANISMS FOR SOFTWARE ENABLED ACCESS

POINT (SOFTAP)

CROSS-REFERENCE TO RELATED APPLICATIONS [0001] This Patent Application claims priority to Indian Provisional Patent Application No. 202041006203 entitled “POWER SAVING MECHANISMS FOR SOFTWARE ENABLED ACCESS POINT (SOFTAP)” and filed on February 13,

2020, which is assigned to the assignee hereof. The disclosure of the prior Application is considered part of and are incorporated by reference in this Patent Application.

TECHNICAL FIELD

[0002] This disclosure relates generally to wireless communication, and more specifically, to power saving mechanisms for software enabled access points (SoftAPs).

DESCRIPTION OF THE RELATED TECHNOLOGY [0003] A wireless local area network (WLAN) may be formed by one or more access points (APs) that provide a shared wireless communication medium for use by a number of client devices also referred to as stations (STAs). The basic building block of a WLAN conforming to the Institute of Electrical and Electronics Engineers (IEEE) 802.11 family of standards is a Basic Service Set (BSS), which is managed by an AP. Each BSS is identified by a Basic Service Set Identifier (BSSID) that is advertised by the AP. An AP periodically broadcasts beacon frames to enable any STAs within wireless range of the AP to establish or maintain a communication link with the WLAN. [0004] A STA can discover one or more BSSs in its vicinity by “scanning” different wireless channels. Existing IEEE 802.11 standards generally define two channel scanning techniques: passive scanning and active scanning. The STA may passively scan the wireless channels by listening for beacon frames that may be broadcast by APs operating on such channels. The STA also may actively scan the wireless channels by transmitting probe requests on each of the channels and listening for probe responses from APs that may be operating on such channels.

[0005] The IEEE 802.1 lax amendment to the IEEE 802.11 wireless communication protocol standard adds support for wireless communications in the 6 GHz frequency band, for example, to provide greater frequency separation between BSSs in dense deployment scenarios (where multiple BSSs can overlap with one another). To reduce congestion in dense deployment scenarios, access to the 6 GHz frequency band is managed or controlled by the AP. Further, STAs are prohibited from actively scanning (or transmitting probe requests on) the 6 GHz frequency band.

[0006] To alleviate the impact on scan time, APs may periodically broadcast fast initial link setup (FILS) discovery frames, in between beacon frames, on the 6 GHz frequency band. Each FILS discovery frame includes identifying information for the corresponding BSS (similar to what is included in the beacon frames). Although the periodic broadcasting of FILS discovery frames may help reduce the scan times of unassociated STAs, such reduction in scan times comes at the cost of increased overhead and power consumption by the AP.

SUMMARY

[0007] The systems, methods and devices of this disclosure each have several innovative aspects, no single one of which is solely responsible for the desirable attributes disclosed herein.

[0008] One innovative aspect of the subject matter described in this disclosure can be implemented as a method of wireless communication. The method can be performed by a wireless communication device to encode data for transmission over a wireless channel. In some implementations, the method can include broadcasting a first beacon frame signaling the start of a first beacon interval; receiving, from each wireless station (STA) associated with the wireless communication device during the first beacon interval, first power management (PM) information indicating whether the STA is in a sleep state or an active state; and broadcasting a number of fast initial link setup (FILS) discovery frames during the first beacon interval based at least in part on the first PM information received from each associated STA. In some implementations, the first PM information may be carried in one or more null frames received in response to the broadcasting of the first beacon frame. In some other implementations, the first PM information may be carried in one or more data frames.

[0009] In some implementations, the method may further include obtaining an indication that each of the associated STAs is in the sleep state during the first beacon interval; initiating a first idle timer based on the indication that each of the associated STAs is in the sleep state during the first beacon interval; activating a power save mode of the wireless communication device responsive to an expiration of the first idle timer; and operating in the power save mode until the end of the first beacon interval. In some implementations, the method may further include monitoring traffic patterns of one or more STAs associated with the wireless communication device during one or more beacon intervals preceding the first beacon interval; and configuring a duration of the first idle timer based at least in part on the monitored traffic patterns. In some implementations, the number of FILS discovery frames broadcast during the first beacon interval may be equal to one.

[0010] In some implementations, the method may further include broadcasting a second beacon frame at the end of the first beacon interval, where the second beacon frame signals the start of a second beacon interval; receiving, from each STA associated with the wireless communication device during the second beacon interval, second PM information indicating whether the STA is in the sleep state or the active state; and broadcasting a number of FILS discovery frames during the second beacon interval based at least in part on the second PM information received from each associated STA. In some implementations, the method may further include obtaining an indication that each of the associated STAs is in the sleep state during the second beacon interval; initiating a second idle timer based on the indication that each of the associated STAs is in the sleep state during the second beacon interval, where the second idle timer has a shorter duration than the first idle timer; activating the power save mode responsive to an expiration of the second idle timer; and operating in the power save mode until the end of the second beacon interval.

[0011] In some implementations, the broadcasting of the FILS discovery frames may include obtaining an indication that a first STA is in the active state during the first beacon interval, where the number of FILS discovery frames broadcast during the first beacon interval is based on a duration in which the first STA remains in the active state. In some implementations, the FILS discovery frames may be broadcast at periodic intervals for the duration in which the first STA remains in the active state. In some implementations, the method may further include receiving, from the first STA, second PM information indicating that the first STA is in the sleep state; activating a power save mode of the wireless communication device based on receiving the second PM information from the first STA; and operating in the power save mode until the end of the first beacon interval. In some implementations, one of the FILS discovery frames may be broadcast after receiving the second PM information from the first STA and prior to activating the power save mode.

[0012] Another innovative aspect of the subject matter described in this disclosure can be implemented in a wireless communication device. The wireless communication device can include one or more processors and a memory. The memory stores instructions that, when executed by the one or more processors, can cause the wireless communication device to broadcast a first beacon frame signaling the start of a first beacon interval; receive, from each STA associated with the wireless communication device during the first beacon interval, first PM information indicating whether the STA is in a sleep state or an active state; and broadcast a number of fast initial link setup (FILS) discovery frames during the first beacon interval based at least in part on the first PM information received from each associated STA.

[0013] Another innovative aspect of the subject matter described in this disclosure can be implemented as a method of wireless communication. The method can be performed by a wireless communication device to decode data received over a wireless channel. In some implementations, the method can include receiving, from an access point (AP), a beacon frame signaling the start of a beacon interval; transmitting a null frame to the AP responsive to receiving the beacon frame, where the null frame carries first PM information indicating a PM mode, where the PM mode is one of a power save mode or an active mode; and operating in the PM mode indicated by the first PM information for a first duration of the beacon interval.

[0014] In some implementations in which the first PM information indicates the active mode, the method may further include receiving one or more FILS discovery frames from the AP at periodic intervals. In some implementations, the method may further include transmitting, to the AP, second PM information indicating that the wireless communication device is in the sleep mode; and operating in the sleep mode for a second duration of the beacon interval. In some implementations, the second PM information may be carried in a data frame.

[0015] Another innovative aspect of the subject matter described in this disclosure can be implemented in a wireless communication device. The wireless communication device can include one or more processors and a memory. The memory stores instructions that, when executed by the one or more processors, can cause the wireless communication device to receive, from an AP, a beacon frame signaling the start of a beacon interval; transmit a null frame to the AP responsive to receiving the beacon frame, where the null frame carries first PM information indicating a PM mode, where the PM mode is one of a power save mode or an active mode; and operate in the PM mode indicated by the first PM information for a duration of the beacon interval.

[0016] Details of one or more implementations of the subject matter described in this disclosure are set forth in the accompanying drawings and the description below. Other features, aspects, and advantages will become apparent from the description, the drawings and the claims. Note that the relative dimensions of the following figures may not be drawn to scale.

BRIEF DESCRIPTION OF THE DRAWINGS [0017] Figure 1 shows a pictorial diagram of an example wireless communication network.

[0018] Figure 2 shows an example protocol data unit (PDU) usable for communications between an access point (AP) and a number of stations (STAs).

[0019] Figure 3 shows an example physical layer convergence protocol (PLCP) protocol data unit (PPDU) usable for communications between an AP and a number of STAs.

[0020] Figure 4 shows a block diagram of an example wireless communication device.

[0021] Figure 5A shows a block diagram of an example access point (AP).

[0022] Figure 5B shows a block diagram of an example station (STA).

[0023] Figures 6A and 6B show a timing diagram illustrating an example message exchange between an AP and a number of STAs according to some implementations. [0024] Figure 7A shows an illustrative flowchart depicting an example operation for reducing power consumption in software enabled access points (SoftAPs).

[0025] Figure 7B shows an illustrative flowchart depicting an example operation for reducing power consumption in SoftAPs.

[0026] Figure 7C shows an illustrative flowchart depicting an example operation for reducing power consumption in SoftAPs.

[0027] Figure 7D shows an illustrative flowchart depicting an example operation for reducing power consumption in SoftAPs. [0028] Figure 7E shows an illustrative flowchart depicting an example operation for reducing power consumption in SoftAPs.

[0029] Figure 8 shows an illustrative flowchart depicting an example operation for reducing power consumption in SoftAPs.

[0030] Figure 9 shows a block diagram of an example wireless communication device for use in wireless communication according to some implementations.

[0031] Figure 10 shows a block diagram of an example wireless communication device for use in wireless communication according to some implementations.

[0032] Like reference numbers and designations in the various drawings indicate like elements.

DETAILED DESCRIPTION

[0033] The following description is directed to certain implementations for the purposes of describing innovative aspects of this disclosure. However, a person having ordinary skill in the art will readily recognize that the teachings herein can be applied in a multitude of different ways. The described implementations can be implemented in any device, system or network that is capable of transmitting and receiving radio frequency (RF) signals according to one or more of the Institute of Electrical and Electronics Engineers (IEEE) 802.11 standards, the IEEE 802.15 standards, the Bluetooth® standards as defined by the Bluetooth Special Interest Group (SIG), or the Long Term Evolution (LTE), 3G, 4G or 5G (New Radio (NR)) standards promulgated by the 3rd Generation Partnership Project (3GPP), among others. The described implementations can be implemented in any device, system or network that is capable of transmitting and receiving RF signals according to one or more of the following technologies or techniques: code division multiple access (CDMA), time division multiple access (TDMA), frequency division multiple access (FDMA), orthogonal FDMA (OFDMA), single-carrier FDMA (SC-FDMA), single-user (SU) multiple-input multiple-output (MIMO) and multi-user (MU) MIMO. The described implementations also can be implemented using other wireless communication protocols or RF signals suitable for use in one or more of a wireless personal area network (WPAN), a wireless local area network (WLAN), a wireless wide area network (WWAN), or an internet of things (IOT) network. [0034] As described above, STAs that operate in accordance with existing IEEE 802.11 standards (such as in accordance with the IEEE 802.1 lax amendment) may be prohibited from actively scanning, or transmitting probe requests on, the 6 GHz frequency band. To alleviate the impact on scan time, APs may periodically broadcast fast initial link setup (FILS) discovery frames, between successive beacon frames, on the 6 GHz frequency band. Each FILS discovery frame includes identifying information for the corresponding BSS such as, for example, beacon interval, SSID, and primary channel. Unlike beacon frames, which are typically broadcast in 100 time-unit (TU) intervals, FILS discovery frames may be broadcast every 20 TUs. Thus, an unassociated STA performing a passive scan operation may discover an AP operating on the 6 GHz frequency band upon receiving one or more FILS discovery frames, without waiting the full duration of a beacon interval on any particular channel.

[0035] Aspects of the present disclosure recognize that, while periodically broadcasting FILS discovery frames may help reduce the scan times of unassociated STAs, such solutions may not be practical for BSSs managed by software enabled access points (SoftAPs). For example, SoftAPs are often implemented by mobile devices (such as smartphones, tablets, or laptops, among other examples) for purposes of providing small or temporary BSSs (also referred to as “mobile hotspots”) that serve a limited number of client devices. Because most (if not all) of the client devices are already known or associated with the SoftAP from the time the BSS is established, there may be little benefit to enabling fast discovery of the BSS by unassociated STAs. On the other hand, the SoftAP may be implemented on a battery-operated mobile device that is not connected to any external power source. Thus, the power requirements of the SoftAP may outweigh the need to reduce scan times for any unassociated STAs.

[0036] Various implementations relate generally to power savings in wireless communication systems. Some implementations more specifically relate to reducing the power consumption of wireless communication devices operating on the 6 GHz frequency band (or any of the 2.4 GHz or 5 GHz bands). In some implementations, a wireless communication device broadcasts a beacon frame signaling the start of a beacon interval and determines a power management (PM) mode of each wireless station (STA) associated with the wireless communication device during the beacon interval. The wireless communication device further broadcasts a number of fast initial link setup (FILS) discovery frames during the beacon interval, where the number of FILS discovery frames is based at least in part on the PM modes of the associated STAs. For example, the wireless communication device may broadcast FILS discovery frames at periodic intervals while at least one of the associated STAs is in an active state. In some implementations, the wireless communication device may broadcast a single FILS discovery frame responsive to determining that each of the associated STAs is in a sleep state. After broadcasting the single FILS discovery frame, the wireless communication device may subsequently operate in a power save mode for the remainder of the beacon interval.

[0037] In some implementations, each associated STA may transmit a null frame to the wireless communication device at the start of the beacon interval, where the null frame includes PM information indicating the PM mode of the respective STA. If the null frames indicate that each of the associated STAs is in a sleep state, the wireless communication device may initiate an idle timer at the start of the beacon interval. The wireless communication device may activate a power save mode upon expiration of the first idle timer and remain in the power save mode until the end of the beacon interval. Thus, if none of the associated STAs intend to communicate with the wireless communication device during the beacon interval, the wireless communication device may transmit only 1 FILS discovery frame for the entirety of the beacon interval.

[0038] Particular implementations of the subject matter described in this disclosure can be implemented to realize one or more of the following potential advantages. In some implementations, the described techniques may be used to reduce the power consumption of client devices or software enabled access points (SoftAPs) operating on any of the 2.4 GHz, 5 GHz, or 6 GHz frequency bands. Unlike static APs, which provide dedicated BSSs, SoftAPs are often implemented by mobile devices (such as smartphones, tablets, or laptops, among other examples) to provide small or temporary BSSs (also referred to as “mobile hotspots”) that serve a limited number of client devices. Because most (if not all) of the client devices are already known or associated with the SoftAP from the time the BSS is established, the power requirements of the SoftAP may outweigh the need to reduce scan times for any unassociated STAs. By dynamically adjusting the number of FILS discovery frames broadcast by a SoftAP based on the PM modes of its associated STAs, the SoftAP may conserve its power when the associated STAs are in a sleep state and not communicating with the SoftAP. Further, configuring each associated STA to indicate its PM mode to the SoftAP at the start of each beacon interval may allow the SoftAP to maximize its power savings for the duration of the beacon interval.

[0039] Figure 1 shows a block diagram of an example wireless communication network 100. According to some aspects, the wireless communication network 100 can be an example of a wireless local area network (WLAN) such as a Wi-Fi network (and will hereinafter be referred to as WLAN 100). For example, the WLAN 100 can be a network implementing at least one of the IEEE 802.11 family of wireless communication protocol standards (such as that defined by the IEEE 802.11-2016 specification or amendments thereof including, but not limited to, 802.1 lah, 802.1 lad, 802.1 lay, 802.1 lax, 802.1 laz, 802.1 lba and 802.1 lbe). The WLAN 100 may include numerous wireless communication devices such as an access point (AP) 102 and multiple stations (STAs) 104. While only one AP 102 is shown, the WLAN network 100 also can include multiple APs 102.

[0040] Each of the STAs 104 also may be referred to as a mobile station (MS), a mobile device, a mobile handset, a wireless handset, an access terminal (AT), a user equipment (UE), a subscriber station (SS), or a subscriber unit, among other possibilities. The STAs 104 may represent various devices such as mobile phones, personal digital assistant (PDAs), other handheld devices, netbooks, notebook computers, tablet computers, laptops, display devices (for example, TVs, computer monitors, navigation systems, among others), music or other audio or stereo devices, remote control devices (“remotes”), printers, kitchen or other household appliances, key fobs (for example, for passive keyless entry and start (PKES) systems), among other possibilities.

[0041] A single AP 102 and an associated set of STAs 104 may be referred to as a basic service set (BSS), which is managed by the respective AP 102. Figure 1 additionally shows an example coverage area 106 of the AP 102, which may represent a basic service area (BSA) of the WLAN 100. The BSS may be identified to users by a service set identifier (SSID), as well as to other devices by a basic service set identifier (BSSID), which may be a medium access control (MAC) address of the AP 102. The AP 102 periodically broadcasts beacon frames (“beacons”) including the BSSID to enable any STAs 104 within wireless range of the AP 102 to “associate” or re-associate with the AP 102 to establish a respective communication link 108 (hereinafter also referred to as a “Wi-Fi link”), or to maintain a communication link 108, with the AP 102. For example, the beacons can include an identification of a primary channel used by the respective AP 102 as well as a timing synchronization function for establishing or maintaining timing synchronization with the AP 102. The AP 102 may provide access to external networks to various STAs 104 in the WLAN via respective communication links 108.

[0042] To establish a communication link 108 with an AP 102, each of the STAs 104 is configured to perform passive or active scanning operations (“scans”) on frequency channels in one or more frequency bands (for example, the 2.4 GHz, 5 GHz,

6 GHz or 60 GHz bands). To perform passive scanning, a STA 104 listens for beacons, which are transmitted by respective APs 102 at a periodic time interval referred to as the target beacon transmission time (TBTT) (measured in time units (TUs) where one TU may be equal to 1024 microseconds (ps)). To perform active scanning, a STA 104 generates and sequentially transmits probe requests on each channel to be scanned and listens for probe responses from APs 102. Each STA 104 may be configured to identify or select an AP 102 with which to associate based on the scanning information obtained through the passive or active scans, and to perform authentication and association operations to establish a communication link 108 with the selected AP 102. The AP 102 assigns an association identifier (AID) to the STA 104 at the culmination of the association operations, which the AP 102 uses to track the STA 104.

[0043] As a result of the increasing ubiquity of wireless networks, a STA 104 may have the opportunity to select one of many BSSs within range of the STA or to select among multiple APs 102 that together form an extended service set (ESS) including multiple connected BSSs. An extended network station associated with the WLAN 100 may be connected to a wired or wireless distribution system that may allow multiple APs 102 to be connected in such an ESS. As such, a STA 104 can be covered by more than one AP 102 and can associate with different APs 102 at different times for different transmissions. Additionally, after association with an AP 102, a STA 104 also may be configured to periodically scan its surroundings to find a more suitable AP 102 with which to associate. For example, a STA 104 that is moving relative to its associated AP 102 may perform a “roaming” scan to find another AP 102 having more desirable network characteristics such as a greater received signal strength indicator (RSSI) or a reduced traffic load. [0044] In some cases, STAs 104 may form networks without APs 102 or other equipment other than the STAs 104 themselves. One example of such a network is an ad hoc network (or wireless ad hoc network). Ad hoc networks may alternatively be referred to as mesh networks or peer-to-peer (P2P) networks. In some cases, ad hoc networks may be implemented within a larger wireless network such as the WLAN 100. In such implementations, while the STAs 104 may be capable of communicating with each other through the AP 102 using communication links 108, STAs 104 also can communicate directly with each other via direct wireless links 110. Additionally, two STAs 104 may communicate via a direct communication link 110 regardless of whether both STAs 104 are associated with and served by the same AP 102. In such an ad hoc system, one or more of the STAs 104 may assume the role filled by the AP 102 in a BSS. Such a STA 104 may be referred to as a group owner (GO) and may coordinate transmissions within the ad hoc network. Examples of direct wireless links 110 include Wi-Fi Direct connections, connections established by using a Wi-Fi Tunneled Direct Link Setup (TDLS) link, and other P2P group connections.

[0045] The APs 102 and STAs 104 may function and communicate (via the respective communication links 108) according to the IEEE 802.11 family of wireless communication protocol standards (such as that defined by the IEEE 802.11-2016 specification or amendments thereof including, but not limited to, 802.1 lah, 802.1 lad, 802.1 lay, 802.1 lax, 802.1 laz, 802.11ba and 802.11be). These standards define the WLAN radio and baseband protocols for the PHY and medium access control (MAC) layers. The APs 102 and STAs 104 transmit and receive wireless communications (hereinafter also referred to as “Wi-Fi communications”) to and from one another in the form of physical layer convergence protocol (PLCP) protocol data units (PPDUs). The APs 102 and STAs 104 in the WLAN 100 may transmit PPDUs over an unlicensed spectrum, which may be a portion of spectrum that includes frequency bands traditionally used by Wi-Fi technology, such as the 2.4 GHz band, the 5 GHz band, the 60 GHz band, the 3.6 GHz band, and the 900 MHz band. Some implementations of the APs 102 and STAs 104 described herein also may communicate in other frequency bands, such as the 6 GHz band, which may support both licensed and unlicensed communications. The APs 102 and STAs 104 also can be configured to communicate over other frequency bands such as shared licensed frequency bands, where multiple operators may have a license to operate in the same or overlapping frequency band or bands.

[0046] Each of the frequency bands may include multiple channels (which may be used as subchannels of a larger bandwidth channel as described below). For example, PPDUs conforming to the IEEE 802.1 In, 802.1 lac and 802.1 lax standard amendments may be transmitted over the 2.4 and 5 GHz bands, each of which is divided into multiple 20 MHz channels. As such, these PPDUs are transmitted over a physical channel having a minimum bandwidth of 20 MHz, but larger channels can be formed through channel bonding. For example, PPDUs may be transmitted over physical channels having bandwidths of 40 MHz, 80 MHz, 160 or 320 MHz by bonding together multiple 20 MHz channels (which may be referred to as subchannels).

[0047] Each PPDU is a composite structure that includes a PHY preamble and a payload in the form of a PLCP service data unit (PSDU). The information provided in the preamble may be used by a receiving device to decode the subsequent data in the PSDU. In instances in which PPDUs are transmitted over a bonded channel, the preamble fields may be duplicated and transmitted in each of the multiple component channels. The PHY preamble may include both a first portion (or “legacy preamble”) and a second portion (or “non-legacy preamble”). The first portion may be used for packet detection, automatic gain control and channel estimation, among other uses. The first portion also may generally be used to maintain compatibility with legacy devices as well as non-legacy devices. The format of, coding of, and information provided in the second portion of the preamble is based on the particular IEEE 802.11 protocol to be used to transmit the payload.

[0048] Figure 2 shows an example protocol data unit (PDU) 200 usable for wireless communication between an AP and a number of STAs. For example, the PDU 200 can be configured as a PPDU. As shown, the PDU 200 includes a PHY preamble 201 and a PHY payload 204. For example, the preamble 201 may include a first portion 202 that itself includes a legacy short training field (L-STF) 206, which may consist of two BPSK symbols, a legacy long training field (L-LTF) 208, which may consist of two BPSK symbols, and a legacy signal field (L-SIG) 210, which may consist of one BPSK symbol. The first portion 202 of the preamble 201 may be configured according to the IEEE 802.1 la wireless communication protocol standard. The preamble 201 may also include a second portion 203 including one or more non-legacy signal fields 212, for example, conforming to an IEEE wireless communication protocol such as the IEEE 802.1 lac, 802.1 lax, 802.1 lbe or later wireless communication protocol standards. [0049] L-STF 206 generally enables a receiving device to perform automatic gain control (AGC) and coarse timing and frequency estimation. L-LTF 208 generally enables a receiving device to perform fine timing and frequency estimation and also to perform an initial estimate of the wireless channel. L-SIG 210 generally enables a receiving device to determine a duration of the PDU and to use the determined duration to avoid transmitting on top of the PDU. For example, L-STF 206, L-LTF 208 and L- SIG 210 may be modulated according to a binary phase shift keying (BPSK) modulation scheme. The payload 204 may 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. The payload 204 may include a PSDU including a data field (DATA) 214 that, in turn, may carry higher layer data, for example, in the form of medium access control (MAC) protocol data units (MPDUs) or an aggregated MPDU (A-MPDU).

[0050] Figure 2 also shows an example L-SIG 210 in the PDU 200. L-SIG 210 includes a data rate field 222, a reserved bit 224, a length field 226, a parity bit 228, and a tail field 230. The data rate field 222 indicates a data rate (note that the data rate indicated in the data rate field 212 may not be the actual data rate of the data carried in the payload 204). The length field 226 indicates a length of the packet in units of, for example, symbols or bytes. The parity bit 228 may be used to detect bit errors. The tail field 230 includes tail bits that may be used by the receiving device to terminate operation of a decoder (for example, a Viterbi decoder). The receiving device may utilize the data rate and the length indicated in the data rate field 222 and the length field 226 to determine a duration of the packet in units of, for example, microseconds (ps) or other time units.

[0051] Figure 3 shows an example PPDU 300 usable for communications between an AP 102 and a number of STAs 104. As described above, each PPDU 300 includes a PHY preamble 302 and a PSDU 304. Each PSDU 304 may carry one or more MAC protocol data units (MPDUs). For example, each PSDU 304 may carry an aggregated MPDU (A-MPDU) 308 that includes an aggregation of multiple A-MPDU subframes 306. Each A-MPDU subframe 306 may include a MAC delimiter 310 and a MAC header 312 prior to the accompanying MPDU 314, which includes the data portion (“payload” or “frame body”) of the A-MPDU subframe 306. The MPDU 314 may carry one or more MAC service data unit (MSDU) subframes 316. For example, the MPDU 314 may carry an aggregated MSDU (A-MSDU) 318 including multiple MSDU subframes 316. Each MSDU subframe 316 contains a corresponding MSDU 320 preceded by a subframe header 322.

[0052] Referring back to the A-MPDU subframe 306, the MAC header 312 may include a number of fields containing information that defines or indicates characteristics or attributes of data encapsulated within the frame body 314. The MAC header 312 also includes a number of fields indicating addresses for the data encapsulated within the frame body 314. For example, the MAC header 312 may include a combination of a source address, a transmitter address, a receiver address or a destination address. The MAC header 312 may include a frame control field containing control information. The frame control field specifies the frame type, for example, a data frame, a control frame, or a management frame. The MAC header 312 may further including a duration field indicating a duration extending from the end of the PPDU until the end of an acknowledgment (ACK) of the last PPDU to be transmitted by the wireless communication device (for example, a block ACK (BA) in the case of an A- MPDU). The use of the duration field serves to reserve the wireless medium for the indicated duration, thus establishing the NAV. Each A-MPDU subframe 306 may also include a frame check sequence (FCS) field 324 for error detection. For example, the FCS field 316 may include a cyclic redundancy check (CRC).

[0053] As described above, APs 102 and STAs 104 can support multi-user (MU) communications; that is, concurrent transmissions from one device to each of multiple devices (for example, multiple simultaneous downlink (DL) communications from an AP 102 to corresponding STAs 104), or concurrent transmissions from multiple devices to a single device (for example, multiple simultaneous uplink (UL) transmissions from corresponding STAs 104 to an AP 102). To support the MU transmissions, the APs 102 and STAs 104 may utilize multi-user multiple-input, multiple-output (MU-MIMO) and multi-user orthogonal frequency division multiple access (MU-OFDMA) techniques. [0054] In MU-OFDMA schemes, the available frequency spectrum of the wireless channel may be divided into multiple resource units (RUs) each including a number of different frequency subcarriers (“tones”). Different RUs may be allocated or assigned by an AP 102 to different STAs 104 at particular times. The sizes and distributions of the RUs may be referred to as an RU allocation. In some implementations, RUs may be allocated in 2 MHz intervals, and as such, the smallest RU may include 26 tones consisting of 24 data tones and 2 pilot tones. Consequently, in a 20 MHz channel, up to 9 RUs (such as 2 MHz, 26-tone RUs) may be allocated (because some tones are reserved for other purposes). Similarly, in a 160 MHz channel, up to 74 RUs may be allocated. Larger 52 tone, 106 tone, 242 tone, 484 tone and 996 tone RUs may also be allocated. Adjacent RUs may be separated by a null subcarrier (such as a DC subcarrier), for example, to reduce interference between adjacent RUs, to reduce receiver DC offset, and to avoid transmit center frequency leakage.

[0055] For UL MU transmissions, an AP 102 can transmit a trigger frame to initiate and synchronize an UL MU-OFDMA or UL MU-MIMO transmission from multiple STAs 104 to the AP 102. Such trigger frames may thus enable multiple STAs 104 to send UL traffic to the AP 102 concurrently in time. A trigger frame may address one or more STAs 104 through respective association identifiers (AIDs), and may assign each AID (and thus each STA 104) one or more RUs that can be used to send UL traffic to the AP 102. The AP also may designate one or more random access (RA) RUs that unscheduled STAs 104 may contend for.

[0056] Figure 4 shows a block diagram of an example wireless communication device 400. In some implementations, the wireless communication device 400 can be an example of a device for use in a STA such as one of the STAs 104 described above with reference to Figure 1. In some implementations, the wireless communication device 400 can be an example of a device for use in an AP such as the AP 102 described above with reference to Figure 1. The wireless communication device 400 is capable of transmitting (or outputting for transmission) and receiving wireless communications (for example, in the form of wireless packets). For example, the wireless communication device can be configured to transmit and receive packets in the form of PPDUs and MPDUs conforming to an IEEE 802.11 standard, such as that defined by the IEEE 802.11-2016 specification or amendments thereof including, but not limited to, 802.11 ah, 802.1 lad, 802.1 lay, 802.1 lax, 802.1 laz, 802.11ba and 802.11be.

[0057] The wireless communication device 400 can be, or can include, a chip, system on chip (SoC), chipset, package or device that includes one or more modems 402, for example, a Wi-Fi (IEEE 802.11 compliant) modem. In some implementations, the one or more modems 402 (collectively “the modem 402”) additionally include a WWAN modem (for example, a 3GPP 4G LTE or 5G compliant modem). In some implementations, the wireless communication device 400 also includes one or more radios 404 (collectively “the radio 404”). In some implementations, the wireless communication device 406 further includes one or more processors, processing blocks or processing elements 406 (collectively “the processor 406”) and one or more memory blocks or elements 408 (collectively “the memory 408”).

[0058] The modem 402 can include an intelligent hardware block or device such as, for example, an application-specific integrated circuit (ASIC) among other possibilities. The modem 402 is generally configured to implement a PHY layer. For example, the modem 402 is configured to modulate packets and to output the modulated packets to the radio 404 for transmission over the wireless medium. The modem 402 is similarly configured to obtain modulated packets received by the radio 404 and to demodulate the packets to provide demodulated packets. In addition to a modulator and a demodulator, the modem 402 may further include digital signal processing (DSP) circuitry, automatic gain control (AGC), a coder, a decoder, a multiplexer and a demultiplexer. For example, while in a transmission mode, data obtained from the processor 406 is provided to a coder, 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. The modulated symbols may then be mapped to a number Nss of spatial streams or a number Ns_/s of space-time streams. The modulated symbols in the respective spatial or space-time streams may then be multiplexed, transformed via an inverse fast Fourier transform (IFFT) block, and subsequently provided to the DSP circuitry for Tx windowing and filtering. The digital signals may then be provided to a digital-to-analog converter (DAC). The resultant analog signals may then be provided to a frequency upconverter, and ultimately, the radio 404. In implementations involving beamforming, the modulated symbols in the respective spatial streams are precoded via a steering matrix prior to their provision to the IFFT block.

[0059] While in a reception mode, digital signals received from the radio 404 are provided to the DSP circuitry, which is configured to acquire a received signal, for example, by detecting the presence of the signal and estimating the initial timing and frequency offsets. The DSP circuitry is further configured to digitally condition the digital signals, for example, using channel (narrowband) filtering, analog impairment conditioning (such as correcting for I/Q imbalance), and applying digital gain to ultimately obtain a narrowband signal. The output of the DSP circuitry may then be fed to the AGC, which is configured to use information extracted from the digital signals, for example, in one or more received training fields, to determine an appropriate gain. The output of the DSP circuitry also is coupled with the demodulator, which is configured to extract modulated symbols from the signal and, for example, compute the logarithm likelihood ratios (LLRs) for each bit position of each subcarrier in each spatial stream. The demodulator is coupled with the decoder, which may be configured to process the LLRs to provide decoded bits. The decoded bits from all of the spatial streams are then fed to the demultiplexer for demultiplexing. The demultiplexed bits may then be descrambled and provided to the MAC layer (the processor 406) for processing, evaluation or interpretation.

[0060] The radio 404 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 transmitters and receivers may include various DSP circuitry including at least one power amplifier (PA) and at least one low-noise amplifier (LNA), respectively. The RF transmitters and receivers may in turn be coupled to one or more antennas. For example, in some implementations, the wireless communication device 400 can include, or be coupled with, multiple transmit antennas (each with a corresponding transmit chain) and multiple receive antennas (each with a corresponding receive chain). The symbols output from the modem 402 are provided to the radio 404, which then transmits the symbols via the coupled antennas. Similarly, symbols received via the antennas are obtained by the radio 404, which then provides the symbols to the modem 402.

[0061] The processor 406 can include an intelligent hardware block or device such as, for example, a processing core, a processing block, a central processing unit (CPU), a microprocessor, a microcontroller, a digital signal processor (DSP), an application- specific integrated circuit (ASIC), a programmable logic device (PLD) such as a field programmable gate array (FPGA), discrete gate or transistor logic, discrete hardware components, or any combination thereof designed to perform the functions described herein. The processor 406 processes information received through the radio 404 and the modem 402, and processes information to be output through the modem 402 and the radio 404 for transmission through the wireless medium. For example, the processor 406 may implement a control plane and 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 the coding and decoding of frames, spatial multiplexing, space-time block coding (STBC), beamforming, and OFDMA resource allocation, among other operations or techniques. In some implementations, the processor 406 may generally control the modem 402 to cause the modem to perform various operations described above.

[0062] The memory 404 can include tangible storage media such as random-access memory (RAM) or read-only memory (ROM), or combinations thereof. The memory 404 also can store non-transitory processor- or computer-executable software (SW) code containing instructions that, when executed by the processor 406, 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, various functions of components disclosed herein, or various blocks or steps of a method, operation, process or algorithm disclosed herein, can be implemented as one or more modules of one or more computer programs.

[0063] Figure 5A shows a block diagram of an example AP 502. For example, the AP 502 can be an example implementation of the AP 102 described with reference to Figure 1. The AP 502 includes a wireless communication device (WCD) 510. For example, the wireless communication device 510 may be an example implementation of the wireless communication device 400 described with reference to Figure 4. The AP 502 also includes multiple antennas 520 coupled with the wireless communication device 510 to transmit and receive wireless communications. In some implementations, the AP 502 additionally includes an application processor 530 coupled with the wireless communication device 510, and a memory 540 coupled with the application processor 530. The AP 502 further includes at least one external network interface 550 that enables the AP 502 to communicate with a core network or backhaul network to gain access to external networks including the Internet. For example, the external network interface 550 may include one or both of a wired (for example, Ethernet) network interface and a wireless network interface (such as a WWAN interface). Ones of the aforementioned components can communicate with other ones of the components directly or indirectly, over at least one bus. The AP 502 further includes a housing that encompasses the wireless communication device 510, the application processor 530, the memory 540, and at least portions of the antennas 520 and external network interface 550.

[0064] Figure 5B shows a block diagram of an example STA 504. For example, the STA 504 can be an example implementation of the STA 104 described with reference to Figure 1. The STA 504 includes a wireless communication device 515. For example, the wireless communication device 515 may be an example implementation of the wireless communication device 400 described with reference to Figure 4. The STA 504 also includes one or more antennas 525 coupled with the wireless communication device 515 to transmit and receive wireless communications. The STA 504 additionally includes an application processor 535 coupled with the wireless communication device 515, and a memory 545 coupled with the application processor 535. In some implementations, the STA 504 further includes a user interface (UI) 555 (such as a touchscreen or keypad) and a display 565, which may be integrated with the UI 555 to form a touchscreen display. In some implementations, the STA 504 may further include one or more sensors 575 such as, for example, one or more inertial sensors, accelerometers, temperature sensors, pressure sensors, or altitude sensors. Ones of the aforementioned components can communicate with other ones of the components directly or indirectly, over at least one bus. The STA 504 further includes a housing that encompasses the wireless communication device 515, the application processor 535, the memory 545, and at least portions of the antennas 525, UI 555, and display 565.

[0065] Figures 6A and 6B show a timing diagram 600 illustrating an example message exchange between an AP and a number of wireless stations STA1 and STA2 according to some implementations. In some implementations, the AP may be one example of the AP 102 of Figure 1 or the AP 502 of Figure 5 A. In some other implementations, the AP may be any wireless communication device (such as the wireless communication device 400 of Figure 4 or the STAs 104 or 504 of Figures 1 and 5B) operating as a SoftAP. In some implementations, each of the wireless stations STA1 and STA2 may be one example of any of the STAs 104 of Figure 1 or the STA 504 of Figure 5B. The wireless stations STA1 and STA2 are associated with the AP throughout the durations illustrated in the timing diagram 600 and may therefore be referred to as “associated” or “client” STAs. [0066] As shown in Figure 6A, time to coincides with a target beacon transmission time (TBTT). Thus, the AP broadcasts a beacon frame at time to to signal the start of a first beacon interval (from times to to ts). Each of the wireless stations STA1 and STA2 is in an active state (or operating in an active mode) to listen for and receive the beacon frame broadcast by the AP at time to. In some implementations, each of the wireless stations STA1 and STA2 may be configured to transmit a respective null frame to the AP in response to receiving the beacon frame. The null frames may include power management (PM) information indicating PM modes of the respective wireless stations STA1 and STA2. In some aspects, the PM information may be included in a PM subfield of a frame control field in the MAC header (such as the MAC header 312 of Figure 3) of the null frame or MPDU. For example, the PM information may be a 1-bit value indicating whether the STA intends to operate in a power save mode (PM=1) or an active mode (PM=0) subsequent to the transmission of the null frame.

[0067] At time ti, STA1 transmits a null frame indicating that it intends to remain in the active state (PMi=0) and STA2 transmits a null frame indicating that it also intends to remain in the active state (PM2=0). For example, a STA may remain in the active state when it has data to send or receive during a particular beacon period. As shown in Figure 6A, STA2 may transmit data frames to, or receive data frames from, the AP between times t2 and t3. At the end of the data transfer, STA2 may further indicate to the AP that it intends to enter a sleep state (or operate in a power save mode). In some aspects, the indication may be signaled using the PM subfield (PM2=1) of a frame control field in the MAC header of the last MPDU transmitted by STA2 to the AP between times t2 and t_3. As shown in Figure 6A, STA2 may enter the sleep state at time t3, and remain in the sleep state for the remainder of the current beacon interval (until time t5). While STA2 is in the sleep state, STA1 may transmit data frames to, or receive data frames from, the AP between times U to ts

[0068] In some implementations, the AP may be configured to broadcast FILS discovery frames, at periodic intervals, while at least one of its associated STAs is in the active state. As shown in Figure 6A, STA1 remains in the active state for the duration of the first beacon interval (from times to to ts). Thus, the AP may periodically broadcast FILS discovery frames between times to and ts. For example, the AP may broadcast a FILS discovery frame every 20 TUs (or milliseconds) or at a rate of 5 times the beacon interval (100 TUs). In other words, the periodic interval associated with each FILS discovery frame may be equal to one-fifth of the beacon interval. As shown in Figure 6A, the AP broadcasts a sequence of 4 FILS discovery frames, at 20-TU intervals, between times to and tv The first FILS discovery frame in the sequence is broadcast 20 TUs after the beacon frame at time to, and the fourth FILS discovery frame in the sequence is broadcast 20 TUs before the next beacon frame (at time ts).

[0069] The AP broadcasts a subsequent beacon frame at time ts to signal the start of a second beacon interval (from times ts to ty). At time ts, STA1 remains in the active state and STA2 wakes up from the sleep state to listen for and receive the beacon frame broadcast by the AP. At time te, STA1 transmits a null frame indicating that it intends to enter the sleep state (PMi=l) and STA2 transmits a null frame indicating that it intends to remain in the active state (PM2=0). As shown in Figure 6A, STA1 enters the sleep state immediately after transmitting the null frame, at time te, and remains in the sleep state for the remainder of the second beacon interval (until time ti>). On the other hand, STA2 may transmit data frames to, or receive data frames from, the AP between times t7 and tx. At the end of the data transfer, STA2 may further indicate to the AP that it intends to enter the sleep state (PM2=1). As shown in Figure 6A, STA2 may enter the sleep state at time ts, and remain in the sleep state for the remainder of the current beacon interval (until time ty).

[0070] Since STA2 remains in the active state until time ts, the AP may periodically broadcast FILS discovery frames from times ts to tx. As shown in Figure 6A, the AP broadcasts 2 FILS discovery frames, at 20-TU intervals, between times ts and ts. In some implementations, the AP may be configured to activate a power save mode responsive to determining that each of its associated STAs is in the sleep state. The AP may broadcast one additional FILS discovery frame after determining that each of the associated STAs is in the sleep state and prior to activating the power save mode. As shown in Figure 6A, the AP broadcasts an additional FILS discovery frame, at time ts, when there are no more associated STAs in the active state. In some implementations, the duration between the one additional FILS discovery frame and the previous FILS discovery frame (if any) broadcast by the AP may be less than the periodic interval (<20 TUs). The AP activates the power save mode immediately after broadcasting the one additional FILS discovery frame, at time ts, and continues to operate in the power save mode for the remainder of the second beacon interval (until time ti>). [0071] The AP broadcasts a subsequent beacon frame at time t₉ to signal the start of a third beacon interval (from times t₉ to tn). At time t₉, each of the wireless stations STA1 and STA2 wakes up from the sleep state to listen for and receive the beacon frame broadcast by the AP. At time tio, STA1 transmits a null frame indicating that it intends to enter the sleep state (PMi=l) and STA2 transmits a null frame indicating that it also intends to enter the sleep state (PM2=1). As shown in Figure 6A, each of the wireless stations STA1 and STA2 enters the sleep state immediately after transmitting the respective null frames, at time tio, and remains in the sleep state for the remainder of the third beacon interval (until time tn).

[0072] In some implementations, the AP may initiate an idle timer responsive to determining that each of its associated STAs intends to enter the sleep state at the start of the beacon interval (based on the PM information included in the null frames) and may activate its power save mode upon expiration of the idle timer. The AP may broadcast a single FILS discovery frame after determining that each of the associated STAs intends to enter the sleep state at the start of the beacon interval and prior to activating the power save mode. As shown in Figure 6A, the AP broadcasts a single FILS discovery frame, at time tn, and activates the power save mode when the idle timer expires at time ti2. In some implementations, the time between the broadcasts of the single FILS discovery frame (at time tn) and the beacon frame (at time t₉) may be equal to the periodic interval (20 TUs). In some other implementations, the time between the broadcasts of the single FILS discovery frame and the beacon frame may be less than the periodic interval (<20 TUs). The AP continues operating in the power save mode until the end of the third beacon interval (at time tn).

[0073] In some implementations, the AP may dynamically adjust the duration of the idle timer for each beacon interval based, at least in part, on the traffic patterns of its associated STAs. For example, the AP may configure the idle timer to have a relatively long duration following one or more beacon intervals containing high data traffic. On the other hand, the AP may configure the idle timer to have a relatively short duration following one or more beacon intervals containing little or no data traffic. In some aspects, the AP may decrease the duration of the idle timer for each successive beacon interval containing no data traffic. In other words, the power save duration of the AP may incrementally increase with each successive beacon interval, in a telescopic fashion, as illustrated in Figure 6B. [0074] With reference to Figure 6B, the AP broadcasts another beacon frame at time ti 3 to signal the start of a fourth beacon interval (from times ti3 to ti₆). At time ti₃, each of the wireless stations STA1 and STA wakes up from the sleep state to listen for and receive the beacon frame broadcast by the AP. At time ti4, STA1 transmits a null frame indicating that it intends to enter the sleep state (PMi=l) and STA2 transmits a null frame indicating that it also intends to enter the sleep state (PM2=1). As shown in Figure 6B, each of the wireless stations STA1 and STA2 enters the sleep state immediately after transmitting the respective null frames, at time ti4, and remains in the sleep state for the remainder of the fourth beacon interval (until time ti₆).

[0075] The AP initiates an idle timer responsive to determining that each of the wireless stations STA1 and STA2 intends to enter the sleep state at the start of the fourth beacon interval. More specifically, the duration of the idle timer in the fourth beacon interval is shorter than the duration of the idle timer in the third beacon interval. The AP broadcasts a single FILS discovery frame after receiving the null frames from each the wireless stations STA1 and STA2, and activates the power save mode when the idle timer expires at time tis. The AP continues operating in the power save mode until the end of the third beacon interval (at time ti6). As shown in Figure 6B, the AP remains in the power save mode for a longer duration in the fourth beacon interval than in the third beacon interval (|ti2 - ti3| < |tis - ti6|).

[0076] The AP broadcasts a subsequent beacon frame at time ti6 to signal the start of a fifth beacon interval (from times ti6 to tif). At time ti6, each of the wireless stations STA1 and STA wakes up from the sleep state to listen for and receive the beacon frame broadcast by the AP. At time t n, STA1 transmits a null frame indicating that it intends to enter the sleep state (PMi=l) and STA2 transmits a null frame indicating that it also intends to enter the sleep state (PM2=1). Each of the wireless stations STA1 and STA2 enters the sleep state immediately after transmitting the respective null frames, at time tn, and remains in the sleep state for the remainder of the fifth beacon interval (until time ti9).

[0077] The AP initiates an idle timer responsive to determining that each of the wireless stations STA1 and STA2 intends to enter the sleep state at the start of the fifth beacon interval. More specifically, the duration of the idle timer in the fifth beacon interval is shorter than the duration of the idle timer in the fourth beacon interval. The AP broadcasts a single FILS discovery frame after receiving the null frames from each the wireless stations STA1 and STA2, and activates the power save mode when the idle timer expires at time tie. The AP continues operating in the power save mode until the end of the fifth beacon interval (at time tif). As shown in Figure 6B, the AP remains in the power save mode for a longer duration in the fifth beacon interval than in the fourth beacon interval (|tis - ti6| < |tis - ti9|).

[0078] The AP broadcasts a subsequent beacon frame at time ti9 to signal the start of a sixth beacon interval (from times ti9 to tn). At time ti9, each of the wireless stations STA1 and STA wakes up from the sleep state to listen for and receive the beacon frame broadcast by the AP. At time ho, STA1 transmits a null frame indicating that it intends to enter the sleep state (PMi=l) and STA2 transmits a null frame indicating that it also intends to enter the sleep state (PM2=1). Each of the wireless stations STA1 and STA2 enters the sleep state immediately after transmitting the respective null frames, at time t2o, and remains in the sleep state for the remainder of the sixth beacon interval (until time t22).

[0079] The AP initiates an idle timer responsive to determining that each of the wireless stations STA1 and STA2 intends to enter the sleep state at the start of the sixth beacon interval. More specifically, the duration of the idle timer in the sixth beacon interval is shorter than the duration of the idle timer in the fifth beacon interval. The AP broadcasts a single FILS discovery frame after receiving the null frames from each the wireless stations STA1 and STA2, and activates the power save mode when the idle timer expires at time t2i. The AP continues operating in the power save mode until the end of the sixth beacon interval (at time t22). As shown in Figure 6B, the AP remains in the power save mode for a longer duration in the sixth beacon interval than in the fifth beacon interval (|tis - ti9| < |t2i - 122|).

[0080] In some implementations, the AP may broadcast a minimum of one FILS discovery frame per beacon interval. In other words, the AP may wait at least one periodic interval (20 TUs) after the start of each beacon interval before entering the power save mode. Thus, as shown in Figure 6B, the period in which the AP remains in the power save mode (from times t2i to t22) during the sixth beacon interval may represent a maximum achievable power save duration of the AP. In some other implementations, the AP may refrain from broadcasting any FILS discovery frames during a given beacon interval when there are no STAs associated with the AP during the beacon interval or when each associated STA enters the sleep state at the start of the beacon interval. For example, the AP may continue to reduce its idle timer duration, for each successive beacon interval containing no data traffic, even as the idle timer duration falls below the periodic interval (20 TUs).

[0081] Figure 7A shows an illustrative flowchart depicting an example operation 700 for reducing power consumption in SoftAPs. The example operation 700 may be performed by a wireless communication device such as an AP (or SoftAP). The AP may be the AP 102 of Figure 1, the AP 502 of Figure 5 A, or any other suitable AP. [0082] The wireless communication device broadcasts a first beacon frame signaling the start of a first beacon interval (702). The wireless communication device receives, from each STA associated with the wireless communication device during the first beacon interval, first PM information indicating whether the STA is in a sleep state or an active state (704). The wireless communication device broadcasts a number of FILS discovery frames during the first beacon interval based at least in part on the first PM information received from each associated STA (706). In some implementations, the first PM information may be carried in one or more null frames received in response to the broadcasting of the first beacon frame. In some other implementations, the first PM information may be carried in one or more data frames.

[0083] Figure 7B shows an illustrative flowchart depicting an example operation 710 for reducing power consumption in SoftAPs. The example operation 710 may be performed by a wireless communication device such as an AP (or SoftAP). The AP may be the AP 102 of Figure 1, the AP 502 of Figure 5 A, or any other suitable AP. In some implementations, the example operation 710 may be performed subsequent the example operation 700 of Figure 7A.

[0084] The wireless communication device obtains an indication that each of the associated STAs is in the sleep state during the first beacon interval (712). The wireless communication device initiates a first idle timer based on the indication that each of the associated STAs is in the sleep state during the first beacon interval (714). The wireless communication device activates a power save mode of the wireless communication device responsive to an expiration of the first idle timer (716). The wireless communication device operates in the power save mode until the end of the first beacon interval (718). In some implementations, the wireless communication device may monitor traffic patterns of one or more STAs associated with the wireless communication device during one or more beacon intervals preceding the first beacon interval, and configure a duration of the first idle timer based at least in part on the monitored traffic patterns. In some implementations, the number of FILS discovery frames broadcast during the first beacon interval may be equal to one.

[0085] Figure 7C shows an illustrative flowchart depicting an example operation 720 for reducing power consumption in SoftAPs. The example operation 720 may be performed by a wireless communication device such as an AP (or SoftAP). The AP may be the AP 102 of Figure 1, the AP 502 of Figure 5 A, or any other suitable AP. In some implementations, the example operation 720 may be performed subsequent the example operation 710 of Figure 7B.

[0086] The wireless communication device broadcasts a second beacon frame at the end of the first beacon interval, where the second beacon frame signals the start of a second beacon interval (722). The wireless communication device receives, from each STA associated with the wireless communication device during the second beacon interval, second PM information indicating whether the STA is in the sleep state or the active state (724). The wireless communication device broadcasts a number of FILS discovery frames during the second beacon interval based at least in part on the second PM information received from each associated STA (726).

[0087] Figure 7D shows an illustrative flowchart depicting an example operation 730 for reducing power consumption in SoftAPs. The example operation 730 may be performed by a wireless communication device such as an AP (or SoftAP). The AP may be the AP 102 of Figure 1, the AP 502 of Figure 5 A, or any other suitable AP. In some implementations, the example operation 730 may be performed subsequent the example operation 720 of Figure 7C.

[0088] The wireless communication device obtains an indication that each of the associated STAs is in the sleep state during the second beacon interval (732). The wireless communication device initiates a second idle timer based on the indication that each of the associated STAs is in the sleep state during the second beacon interval, where the second idle timer has a shorter duration than the first idle timer (734). The wireless communication device activates the power save mode responsive to an expiration of the second idle timer (736). The wireless communication device operates in the power save mode until the end of the second beacon interval (738).

[0089] Figure 7E shows an illustrative flowchart depicting an example operation 740 for reducing power consumption in SoftAPs. The example operation 740 may be perfonned by a wireless communication device such as an AP (or SoftAP). The AP may be the AP 102 of Figure 1, the AP 502 of Figure 5 A, or any other suitable AP. The example operation 740 may be a more detailed implementation for the broadcasting of FILS discovery frames in the example operation 700 of Figure 7A.

[0090] The wireless communication device obtains an indication that a first STA is in the active state during the first beacon interval, where the number of FILS discovery frames broadcast during the first beacon interval is based on a duration in which the first STA remains in the active state (742). In some implementations, the FILS discovery frames may be broadcast at periodic intervals for the duration in which the first STA remains in the active state. In some implementations, the wireless communication device may further receive, from the first STA, second PM information indicating that the first STA is in the sleep state (744). In some implementations, the wireless communication device may further activate a power save mode of the wireless communication device based on receiving the second PM information from the first STA (746). In some implementations, the wireless communication device may further operate in the power save mode until the end of the first beacon interval (748). In some implementations, one of the FILS discovery frames may be broadcast after receiving the second PM information from the first STA and prior to activating the power save mode. [0091] Figure 8 shows an illustrative flowchart depicting an example operation 800 for reducing power consumption in SoftAPs. The example operation 800 may be performed by a wireless communication device such as a STA. The STA may be any of the STAs 104 of Figure 1, the STA 504 of Figure 5B, or any other suitable STA.

[0092] The wireless communication device receives, from an AP, a beacon frame signaling the start of a beacon interval (802). The wireless communication device transmits a null frame to the AP responsive to receiving the beacon frame, where the null frame carries first PM information indicating a PM mode, where the PM mode is one of a power save mode or an active mode (804). The wireless communication device operates in the PM mode indicated by the first PM information for a first duration of the beacon interval (806). In some implementations in which the first PM information indicates the active mode, the wireless communication device may further receive one or more FILS discovery frames from the AP at periodic intervals. In some implementations, the wireless communication device may further transmit, to the AP, second PM information indicating that the wireless communication device is in the sleep mode and operate in the sleep mode for a second duration of the beacon interval. In some implementations, the second PM information may be carried in a data frame. [0093] Figure 9 shows a block diagram of an example wireless communication device 900 for use in wireless communication according to some implementations. In some implementations, the wireless communication device 900 is configured to perform any of the processes 700-740 described above with reference to Figures 7A-7E, respectively. In some implementations, the wireless communication device 900 can be an example implementation of the wireless communication device 400 described above with reference to Figure 4. For example, the wireless communication device 900 can be a chip, SoC, chipset, package or device that includes at least one processor and at least one modem (for example, a Wi-Fi (IEEE 802.11) modem or a cellular modem). In some implementations, the wireless communication device 900 can be a device for use in an AP, such as one of the APs 102 or 502 described above with reference to Figures 1 and 5A, respectively, or the AP described above with reference to Figures 6A and 6B. [0094] The wireless communication device 900 includes a module for broadcasting beacon frames 902, a module for receiving PM information 904, and a module for broadcasting FILS discovery frames 906. Portions of one or more of the modules 902, 904, and 906 may be implemented at least in part in hardware or firmware. In some implementations, at least some of the modules 902, 904, and 906 are implemented at least in part as software stored in a memory (such as the memory 408). For example, portions of one or more of the modules 902, 904, and 906 can be implemented as non- transitory instructions (or “code”) executable by a processor (such as the processor 406) to perform the functions or operations of the respective module.

[0095] The module for broadcasting beacon frames 902 is configured to broadcast a beacon frame signaling the start of a beacon interval. The module for receiving PM information 904 is configured to receive, from each STA associated with the wireless communication device during the beacon interval, PM information indicating whether the STA is in a sleep state or an active state. The module for broadcasting FILS discovery frames 906 is configured to broadcast a number of FILS discovery frames during the beacon interval based at least in part on the PM information received from each associated STAs.

[0096] Figure 10 shows a block diagram of an example wireless communication device 1000 for use in wireless communication according to some implementations. In some implementations, the wireless communication device 1000 is configured to perform the process 800 described above with reference to Figure 8. In some implementations, the wireless communication device 1000 can be an example implementation of the wireless communication device 400 described above with reference to Figure 4. For example, the wireless communication device 1000 can be a chip, SoC, chipset, package or device that includes at least one processor and at least one modem (for example, a Wi-Fi (IEEE 802.11) modem or a cellular modem). In some implementations, the wireless communication device 1000 can be a device for use in a STA, such as one of the STAs 104 or 504 described above with reference to Figures 1 and 5B, respectively, or any of the wireless stations STA1 or STA2 described above with reference to Figures 6 A and 6B.

[0097] The wireless communication device 1000 includes a module for receiving beacon frames 1002, a module for transmitting null frames 1004, and a module for operating in a PM mode 1006. Portions of one or more of the modules 1002, 1004, and 1006 may be implemented at least in part in hardware or firmware. In some implementations, at least some of the modules 1002, 1004, and 1006 are implemented at least in part as software stored in a memory (such as the memory 408). For example, portions of one or more of the modules 1002, 1004, and 1006 can be implemented as non-transitory instructions (or “code”) executable by a processor (such as the processor 406) to perform the functions or operations of the respective module.

[0098] The module for receiving beacon frames 1002 is configured to receive, from an AP, a beacon frame signaling the start of a beacon interval. The module for transmitting null frames 1004 is configured to transmit a null frame to the AP responsive to receiving the beacon frame, where the null frame carries PM information indicating a PM mode, where the PM mode is one of a power save mode or an active mode. The module for operating in a PM mode 1006 is configured to operate in the PM mode indicated by the PM information for a duration of the beacon interval.

[0099] As used herein, a phrase referring to “at least one of’ or “one or more of’ a list of items refers to any combination of those items, including single members. For example, “at least one of: a, b, or c” is intended to cover the possibilities of: a only, b only, c only, a combination of a and b, a combination of a and c, a combination of b and c, and a combination of a and b and c. [0100] The various illustrative components, logic, logical blocks, modules, circuits, operations and algorithm processes described in connection with the implementations disclosed herein may be implemented as electronic hardware, firmware, software, or combinations of hardware, firmware or software, including the structures disclosed in this specification and the structural equivalents thereof. The interchangeability of hardware, firmware and software has been described generally, in terms of functionality, and illustrated in the various illustrative components, blocks, modules, circuits and processes described above. Whether such functionality is implemented in hardware, firmware or software depends upon the particular application and design constraints imposed on the overall system.

[0101] Implementation examples are described in the following numbered clauses:

1. A method of wireless communication performed by a wireless communication device, including: broadcasting a first beacon frame signaling the start of a first beacon interval; receiving, from each wireless station (STA) associated with the wireless communication device during the first beacon interval, first power management (PM) information indicating whether the STA is in a sleep state or an active state; and broadcasting a number of fast initial link setup (FILS) discovery frames during the first beacon interval based at least in part on the first PM information received from each associated STA.

2. The method of clause 1, where the first PM information is carried in one or more null frames received in response to the broadcasting of the first beacon frame.

3. The method of clause 1, where the first PM information is carried in one or more data frames.

4. The method of any of clauses 1-3, further including: obtaining an indication that each of the associated STAs is in the sleep state during the first beacon interval; initiating a first idle timer based on the indication that each of the associated STAs is in the sleep state during the first beacon interval; activating a power save mode of the wireless communication device responsive to an expiration of the first idle timer; and operating in the power save mode until the end of the first beacon interval.

5. The method of any of clauses 1-4, further including: monitoring traffic patterns of one or more STAs associated with the wireless communication device during one or more beacon intervals preceding the first beacon interval; and configuring a duration of the first idle timer based at least in part on the monitored traffic patterns.

6. The method of any of clauses 1-5, where the number of FILS discovery frames broadcast during the first beacon interval is equal to one.

7. The method of any of clauses 1-6, further including: broadcasting a second beacon frame at the end of the first beacon interval, the second beacon frame signaling the start of a second beacon interval; receiving, from each STA associated with the wireless communication device during the second beacon interval, second PM information indicating whether the STA is in the sleep state or the active state; and broadcasting a number of FILS discovery frames during the second beacon interval based at least in part on the second PM information received from each associated STA.

8. The method of any of clauses 1-7, further including: obtaining an indication that each of the associated STAs is in the sleep state during the second beacon interval; initiating a second idle timer based on the indication that each of the associated STAs is in the sleep state during the second beacon interval, the second idle timer having a shorter duration than the first idle timer; activating the power save mode responsive to an expiration of the second idle timer; and operating in the power save mode until the end of the second beacon interval.

9. The method of any of clauses 1-3, where the broadcasting of the FILS discovery frames includes: obtaining an indication that a first STA is in the active state during the first beacon interval, the number of FILS discovery frames broadcast during the first beacon interval being based on a duration in which the first STA remains in the active state.

10. The method of any of clauses 1-3 or 9, where the FILS discovery frames are broadcast at periodic intervals for the duration in which the first STA remains in the active state.

11. The method of any of clauses 1-3, 9, or 10, further including: receiving, from the first STA, second PM information indicating that the first STA is in the sleep state; activating a power save mode of the wireless communication device based on receiving the second PM information from the first STA; and operating in the power save mode until the end of the first beacon interval.

12. The method of any of clauses 1-3 or 9-11, where one of the FILS discovery frames is broadcast after receiving the second PM information from the first STA and prior to activating the power save mode.

13. A wireless communication device including: one or more processors; and a memory coupled to the one or more processors and including instructions that, when executed by the one or more processors, cause the wireless device to perform the method of any one or more of clauses 1-12.

14. A method for wireless communication performed by a wireless communication device, including: receiving, from an access point (AP), a beacon frame signaling the start of a beacon interval; transmitting a null frame to the AP responsive to receiving the beacon frame, the null frame carrying first power management (PM) information indicating a PM mode, the PM mode being one of a power save mode or an active mode; and operating in the PM mode indicated by the first PM information for a first duration of the beacon interval.

15. The method of clause 14, where the first PM information indicates the active mode, the method further including: receiving one or more fast initial link setup (FILS) discovery frames from the AP at periodic intervals.

16. The method of any of clauses 14 or 15, further including: transmitting, to the AP, second PM information indicating that the wireless communication device is in the sleep mode; and operating in the sleep mode for a second duration of the beacon interval.

17. The method of any of clauses 14-16, where the second PM information is carried in a data frame.

18. A wireless communication device including: one or more processors; and a memory coupled to the one or more processors and including instructions that, when executed by the one or more processors, cause the wireless device to perform the method of any one or more of clauses 14-17.

[0102] Various modifications to the implementations described in this disclosure may be readily apparent to persons having ordinary skill in the art, and the generic principles defined herein may be applied to other implementations without departing from the spirit or scope of this disclosure. Thus, the claims are not intended to be limited to the implementations shown herein, but are to be accorded the widest scope consistent with this disclosure, the principles and the novel features disclosed herein. [0103] Additionally, various features that are described in this specification in the context of separate implementations also can be implemented in combination in a single implementation. Conversely, various features that are described in the context of a single implementation also can be implemented in multiple implementations separately or in any suitable subcombination. As such, although features may be described above as acting in particular combinations, and even initially claimed as such, one or more features from a claimed combination can in some cases be excised from the combination, and the claimed combination may be directed to a subcombination or variation of a subcombination.

[0104] Similarly, while operations are depicted in the drawings in a particular order, this should not be understood as requiring that such operations be performed in the particular order shown or in sequential order, or that all illustrated operations be performed, to achieve desirable results. Further, the drawings may schematically depict one more example processes in the form of a flowchart or flow diagram. However, other operations that are not depicted can be incorporated in the example processes that are schematically illustrated. For example, one or more additional operations can be performed before, after, simultaneously, or between any of the illustrated operations. In some circumstances, multitasking and parallel processing may be advantageous. Moreover, the separation of various system components in the implementations described above should not be understood 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

CLAIMS What is claimed is:

1. A method for wireless communication performed by a wireless communication device, comprising: broadcasting a first beacon frame signaling the start of a first beacon interval; receiving, from each wireless station (STA) associated with the wireless communication device during the first beacon interval, first power management (PM) information indicating whether the STA is in a sleep state or an active state; and broadcasting a number of fast initial link setup (FILS) discovery frames during the first beacon interval based at least in part on the first PM information received from each associated STA.

2. The method of claim 1, wherein the first PM information is carried in one or more null frames received in response to the broadcasting of the first beacon frame.

3. The method of claim 1, wherein the first PM information is carried in one or more data frames.

4. The method of claim 1, further comprising: obtaining an indication that each of the associated STAs is in the sleep state during the first beacon interval; initiating a first idle timer based on the indication that each of the associated STAs is in the sleep state during the first beacon interval; activating a power save mode of the wireless communication device responsive to an expiration of the first idle timer; and operating in the power save mode until the end of the first beacon interval.

5. The method of claim 4, further comprising: monitoring traffic patterns of one or more STAs associated with the wireless communication device during one or more beacon intervals preceding the first beacon interval; and configuring a duration of the first idle timer based at least in part on the monitored traffic patterns.

6. The method of claim 4, wherein the number of FILS discovery frames broadcast during the first beacon interval is equal to one.

7. The method of claim 4, further comprising: broadcasting a second beacon frame at the end of the first beacon interval, the second beacon frame signaling the start of a second beacon interval; receiving, from each STA associated with the wireless communication device during the second beacon interval, second PM information indicating whether the STA is in the sleep state or the active state; and broadcasting a number of FILS discovery frames during the second beacon interval based at least in part on the second PM information received from each associated STA.

8. The method of claim 7, further comprising: obtaining an indication that each of the associated STAs is in the sleep state during the second beacon interval; initiating a second idle timer based on the indication that each of the associated STAs is in the sleep state during the second beacon interval, the second idle timer having a shorter duration than the first idle timer; activating the power save mode responsive to an expiration of the second idle timer; and operating in the power save mode until the end of the second beacon interval.

9. The method of claim 1, wherein the broadcasting of the FILS discovery frames comprises: obtaining an indication that a first STA is in the active state during the first beacon interval, the number of FILS discovery frames broadcast during the first beacon interval being based on a duration in which the first STA remains in the active state.

10. The method of claim 9, wherein the FILS discovery frames are broadcast at periodic intervals for the duration in which the first STA remains in the active state.

11. The method of claim 9, further comprising: receiving, from the first STA, second PM information indicating that the first STA is in the sleep state; activating a power save mode of the wireless communication device based on receiving the second PM information from the first STA; and operating in the power save mode until the end of the first beacon interval.

12. The method of claim 11, wherein one of the FILS discovery frames is broadcast after receiving the second PM information from the first STA and prior to activating the power save mode.

13. A wireless communication device comprising: one or more processors; and a memory coupled to the one or more processors and including instructions that, when executed by the one or more processors, cause the wireless device to: broadcast a first beacon frame signaling the start of a first beacon interval; receive, from each wireless station (STA) associated with the wireless communication device during the first beacon interval, first power management (PM) information indicating whether the STA is in a sleep state or an active state; and broadcast a number of fast initial link setup (FILS) discovery frames during the first beacon interval based at least in part on the first PM information received from each associated STA.

14. The wireless communication device of claim 13, wherein the first PM information is carried in one or more null frames received in response to the broadcasting of the first beacon frame.

15. The wireless communication device of claim 13, wherein the first PM information is carried in one or more data frames.

16. The wireless communication device of claim 13, wherein execution of the instructions further causes the wireless communication device to: obtain an indication that each of the associated STAs is in the sleep state during the first beacon interval; initiate a first idle timer based on the indication that each of the associated STAs is in the sleep state during the first beacon interval; activate a power save mode of the wireless communication device responsive to an expiration of the first idle timer; and operate in the power save mode until the end of the first beacon interval.

17. The wireless communication device of claim 16, wherein execution of the instructions further causes the wireless communication device to: monitor traffic patterns of one or more STAs associated with the wireless communication device during one or more beacon intervals preceding the first beacon interval; and configure a duration of the first idle timer based at least in part on the monitored traffic patterns.

18. The wireless communication device of claim 16, wherein the number of FILS discovery frames broadcast during the first beacon interval is equal to one.

19. The wireless communication device of claim 16, wherein execution of the instructions further causes the wireless communication device to: broadcast a second beacon frame at the end of the first beacon interval, the second beacon frame signaling the start of a second beacon interval; receive, from each STA associated with the wireless communication device during the second beacon interval, second PM information indicating whether the STA is in the sleep state or the active state; and broadcast a number of FILS discovery frames during the second beacon interval based at least in part on the second PM information received from each associated STA.

20. The wireless communication device of claim 19, wherein execution of the instructions further causes the wireless communication device to: obtain an indication that each of the associated STAs is in the sleep state during the second beacon interval; initiate a second idle timer based on the indication that each of the associated STAs is in the sleep state during the second beacon interval, the second idle timer having a shorter duration than the first idle timer; activate the power save mode responsive to an expiration of the second idle timer; and operate in the power save mode until the end of the second beacon interval.

21. The wireless communication device of claim 13, wherein the broadcasting of the FILS discovery frames comprises: obtain an indication that a first STA is in the active state during the first beacon interval, the number of FILS discovery frames broadcast during the first beacon interval being based on a duration in which the first STA remains in the active state.

22. The wireless communication device of claim 21, wherein the FILS discovery frames are broadcast at periodic intervals for the duration in which the first STA remains in the active state.

23. The wireless communication device of claim 21, wherein execution of the instructions further causes the wireless communication device to: receive, from the first STA, second PM information indicating that the first STA is in the sleep state; activate a power save mode of the wireless communication device based on receiving the second PM information from the first STA; and operate in the power save mode until the end of the first beacon interval.

24. The wireless communication device of claim 23, wherein one of the FILS discovery frames is broadcast after receiving the second PM information from the first STA and prior to activating the power save mode.

25. A method for wireless communication performed by a wireless communication device, comprising: receiving, from an access point (AP), a beacon frame signaling the start of a beacon interval; transmitting a null frame to the AP responsive to receiving the beacon frame, the null frame carrying first power management (PM) information indicating a PM mode, the PM mode being one of a power save mode or an active mode; and operating in the PM mode indicated by the first PM information for a first duration of the beacon interval.

26. The method of claim 25, wherein the first PM information indicates the active mode, the method further comprising: receiving one or more fast initial link setup (FILS) discovery frames from the AP at periodic intervals.

27. The method of claim 26, further comprising: transmitting, to the AP, second PM information indicating that the wireless communication device is in the sleep mode; and operating in the sleep mode for a second duration of the beacon interval.

28. The method of claim 27, wherein the second PM information is carried in a data frame.

29. A wireless communication device comprising: one or more processors; and a memory coupled to the one or more processors and including instructions that, when executed by the one or more processors, cause the wireless device to: receive, from an access point (AP), a beacon frame signaling the start of a beacon interval; transmit a null frame to the AP responsive to receiving the beacon frame, the null frame carrying first power management (PM) information indicating a PM mode, the PM mode being one of a power save mode or an active mode; and operate in the PM mode indicated by the first PM information for a duration of the beacon interval.

30. The wireless communication device of claim 29, wherein the first PM information indicates the active mode, execution of the instructions further causing the wireless communication device to: transmit, to the AP, second PM information indicating that the wireless communication device is in the sleep mode; and operate in the sleep mode for a second duration of the beacon interval.