Reducing Listen Mode Power Consumption of Wireless Local Area Network (WLAN) Devices

Abstract

The present disclosure provides a method, device, and system for reducing power consumption when a station (STA) operates in a listen mode. In some aspects, to reduce power consumption in the listen mode, the STA may alternate between monitoring a wireless channel for packets and not monitoring the wireless channel. When the STA is monitoring a wireless channel for packets in the listen mode, the STA may configure a packet detection component to a powered-on state. When the STA is not monitoring a wireless channel in the listen mode, the STA may configure a packet detection component to a powered-down state. During the powered-on state of the listen mode, the STA may detect a preamble of a packet transmitted over the wireless channel. In response to detecting the preamble of the packet, the STA may switch from the listen mode to a receive mode to process the packet.

Description

[Technical Field]

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS This patent application claims priority to U.S. Non-Provisional Patent Application No. 17 / 214,481, filed March 26, 2021, entitled "REDUCING LISTEN MODE POWER CONSUMPTION OF A WIRELESS LOCAL AREA NETWORK (WLAN) DEVICE," and assigned to the assignee of the present application. The disclosure of the prior application is considered part of, and incorporated by reference into, this patent application.

[0002] The present disclosure relates generally to the field of wireless communications and to reducing power consumption of wireless local area network (WLAN) devices operating in listen mode. [Background technology]

[0003] A wireless local area network (WLAN) may be formed by one or more wireless access points (APs), which provide a shared wireless communication medium for use by multiple client devices, sometimes called wireless 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 the basic service set (BSS), which is managed by the AP. Each BSS is identified by a service set identifier (SSID), which is advertised by the AP. The AP periodically broadcasts beacon frames to enable other STAs within wireless range of the AP to establish or maintain a communication link with the WLAN.

[0004] In a WLAN, a STA may monitor a wireless channel for packets or other information. If the STA detects a packet on the wireless channel, the STA may receive the packet and perform operations to process the packet. As the STA monitors the wireless channel, detects packets, and performs operations to receive packets, the STA may operate in various modes. For example, the STA may operate in a listen mode when monitoring the wireless channel. The STA may operate in a receive mode when receiving and processing packets. When the STA is not expecting communication over the wireless channel, the STA may operate in a sleep mode, in which the STA does not consume resources monitoring the wireless channel. Summary of the Invention [Means for solving the problem]

[0005] The systems, methods, and devices of the present disclosure each have several inventive aspects, no single aspect of which is solely responsible for the desirable attributes disclosed herein.

[0006] One inventive aspect of the subject matter described in this disclosure may be embodied in a method for wireless communication performed by a first access point (AP) apparatus in a wireless local area network (WLAN). The method may include alternating one or more components of the first WLAN device between a powered-down state and a powered-on state while the first WLAN device is in a listen mode. The method may include receiving packet preamble information from a second WLAN device during the powered-on state.

[0007] Another inventive aspect of the subject matter described in this disclosure may be embodied in an apparatus of a first WLAN device for wireless communication. The apparatus of the first WLAN device may include a processor configured to alternate one or more components of the first WLAN device between a powered-down state and a powered-on state during a listen mode of the first WLAN device. The apparatus of the first WLAN device may include an interface configured to obtain packet preamble information from a second WLAN device during the powered-on state.

[0008] Another inventive aspect of the subject matter described in this disclosure may be embodied in a non-transitory computer-readable medium storing instructions that, when executed by a processor of a first WLAN device, cause the first WLAN device to perform operations for communication in a WLAN. The operations may cause the first WLAN device to alternate one or more components of the first WLAN device between a powered-down state and a powered-on state while the first WLAN device is in a listen mode. The operations may cause the first WLAN device to obtain packet preamble information from a second WLAN device while in the powered-on state.

[0009] Another inventive aspect of the subject matter described in this disclosure may be embodied in an apparatus of a first WLAN device for wireless communication. The apparatus of the first WLAN device may include means for alternating one or more components of the first WLAN device between a powered-down state and a powered-on state during a listen mode of the first WLAN device. The apparatus of the first WLAN device may include means for obtaining packet preamble information from a second WLAN device during the powered-on state.

[0010] Aspects of the subject matter described in this disclosure may be embodied in a device, software program, system, or other means for performing any of the methods described above.

[0011] The details of one or more aspects 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, drawings, and claims. Please note that the relative dimensions of the following figures may not be drawn to scale. [Brief explanation of the drawings]

[0012] [Figure 1] FIG. 1 is a system diagram of an example wireless communication network. [Figure 2] 1 illustrates an exemplary station (STA) alternating between modes and power states as it monitors for and processes packets over a wireless channel. [Figure 3] 1 illustrates an exemplary STA alternating between modes and power states as it monitors for beacon frames over a wireless channel. [Figure 4] 1 is a block diagram illustrating an example STA including a power state controller that can control the power state of the STA. [Figure 5] FIG. 1 illustrates an example of a listen mode alternating between a powered-up state and a powered-down state when monitoring for physical layer (PHY) protocol data units (PPDUs). [Figure 6] 1 illustrates exemplary operation, timing, and power states for detecting a packet preamble of a PPDU in listen mode. [Figure 7] 1 illustrates a process for wireless communication in a wireless local area network (WLAN), including example operations performed by a device of a STA. [Figure 8] FIG. 1 is a block diagram of an example wireless communication device. [Figure 9A] FIG. 1 is a block diagram of an exemplary access point (AP). [Figure 9B] FIG. 2 is a block diagram of an exemplary STA. [Figure 10]FIG. 1 is a block diagram of an exemplary electronic device for implementing aspects of the present disclosure. DETAILED DESCRIPTION OF THE INVENTION

[0013] Like reference numbers and designations in the various drawings indicate like elements.

[0014] For purposes of describing inventive aspects of the present disclosure, the following description is directed to several aspects. However, those skilled in the art will readily recognize that the teachings herein can be applied in many different ways. The examples in this disclosure are based on wireless local area network (WLAN) communications according to the Institute of Electrical and Electronics Engineers (IEEE) 802.11 wireless standard. However, the described aspects may be applied to other wireless networks, including the IEEE 802.11 standard, the Bluetooth standard, code division multiple access (CDMA), frequency division multiple access (FDMA), time division multiple access (TDMA), Global System for Mobile Communications (GSM), GSM / General Packet Radio Service (GPRS), Enhanced Data GSM Environment (EDGE), Terrestrial Based Radio (TETRA), Wideband CDMA (W-CDMA), Evolution Data Optimized (EV-DO), 1xEV-DO, EV-DO Rev A, EV-DO Rev B, and EV-DO Rev C. B, may be implemented in any device, system, or network capable of transmitting and receiving radio frequency (RF) signals in accordance with one or more of the following: High Speed ​​Packet Access (HSPA), High Speed ​​Downlink Packet Access (HSDPA), High Speed ​​Uplink Packet Access (HSUPA), Evolved High Speed ​​Packet Access (HSPA+), Long Term Evolution (LTE), AMPS, or other known signals used to communicate within a wireless network, cellular network, or Internet of Things (IoT) network, such as a system utilizing 3G, 4G, 5G, 6G technology, or further implementations thereof.

[0015] A wireless local area network (WLAN) in a home, apartment, business, or other type of environment may include two or more WLAN devices. A WLAN may include one or more access points (APs) and one or more stations (STAs). An AP is a type of STA that performs distribution system access functions in a WLAN. For brevity, this disclosure refers to WLAN devices that can operate as either an AP or an STA. An AP may provide wireless access to STAs located within the AP's coverage area. STAs may include various types of WLAN devices, such as mobile phones, laptops, gaming systems (including virtual reality and augmented reality systems (VR and AR, or collectively XR)), entertainment systems, smart appliances, wearable devices, and IoT devices. Some APs may be capable of establishing connectivity over two or more frequency bands. For example, an AP may operate a first basic service set (BSS) on a first frequency band (such as the 2.4 GHz frequency band) and a second BSS on a second frequency band (such as the 5 GHz frequency band). For brevity, the first and second BSSs may be referred to as the AP's first frequency band and the AP's second frequency band, respectively.

[0016] In a WLAN, a STA may utilize various operating modes, including a listen mode, a receive mode, and a sleep mode. In the listen mode, the STA may continuously monitor the wireless channel for packets. To continuously monitor the wireless channel in the listen mode, the STA may continuously provide power to components that detect packets on the wireless channel. If the STA detects a packet, the STA may enter a receive mode to process the detected packet. While processing a packet in the receive mode, the STA may continuously consume power. If the STA does not expect communication for a relatively long duration, the STA may enter a sleep mode in which the STA ceases monitoring the wireless channel. In the sleep mode, the STA may conserve power by stopping providing power to packet detection components. The STA may notify the AP before entering the sleep mode, so the AP does not transmit packets to the STA while the STA is in the sleep mode. After the STA exits the sleep mode, the AP may resume transmitting packets to the STA. Operating in the sleep mode may cause greater latency to packet delivery, so the STA may avoid sleep mode in many situations. To avoid sleep mode, a STA may spend a significant amount of time in listen mode, continuously powering its packet detection components.

[0017] Various aspects of the present disclosure generally relate to techniques for conserving power when a STA is monitoring a wireless channel for packets. Some aspects, more particularly, relate to a STA capable of implementing a listen mode that reduces power consumption. To reduce power consumption in the listen mode, the STA may alternate between monitoring the wireless channel for packets and not monitoring the wireless channel. When the STA is monitoring the wireless channel for packets in the listen mode, the STA may configure a packet detection component to a powered-on state. When the STA is not monitoring the wireless channel in the listen mode, the STA may configure a packet detection component to a powered-down state. The packet detection component of the STA may include one or more components of an RF front end, an analog-to-digital converter (ADC), and one or more components of a baseband processing unit. In some implementations, the STA may alternate between a powered-on state and a powered-down state based on a duty cycle, as further described herein. During the powered-on state of the listen mode, the STA may detect the preamble of a packet transmitted over the wireless channel. In response to detecting the packet preamble, the STA may switch from listen mode to receive mode, in which the STA may remain powered on to receive and process packets.

[0018] In some implementations, in listen mode, a STA may detect a packet preamble by performing autocorrelation on information received over a wireless channel. For example, the STA may perform autocorrelation to detect legacy short training field (L-STF) and legacy long training field (L-LTF) information in a physical layer (PHY) protocol data unit (PPDU). In listen mode, the STA's packet detection component may remain in a powered-on state for a duration that allows the STA to perform autocorrelation. If the STA does not detect a packet preamble, the STA may switch to a powered-down state in listen mode. However, if the STA detects a packet preamble, the STA may remain in a powered-on state and enter a receive mode in which the STA processes the packet. In some implementations, the duration of time spent performing autocorrelation in a powered-on state may be based on a received signal strength indicator (RSSI) associated with the packet, a channel condition metric (such as a signal-to-noise (SNR) ratio or channel congestion), or other suitable metric, as described further herein.

[0019] In some implementations, a STA may detect a packet preamble by performing matched filtering on information received over a wireless channel. For example, the STA may perform matched filtering to detect the L-STF and L-LTF symbols of a PPDU. If the STA does not detect a preamble, the STA may enter a powered-down state in listen mode.

[0020] Particular implementations of the subject matter described in this disclosure may be implemented to achieve one or more of the following potential advantages: Conventional techniques for monitoring a wireless channel in listen mode may involve continuously powering packet detection components as they continuously monitor the wireless channel. In some implementations, a STA may intermittently monitor the wireless channel for packet preambles in listen mode. By intermittently monitoring the wireless channel, the STA may reduce power consumed while in listen mode. For STAs that do not include a cooling fan, reducing power consumption allows the STA to operate at a lower temperature. For STAs that operate on battery power, reducing power consumption may extend the battery life of the STA. The techniques described herein may further reduce the power consumption of a STA when future wireless standards (such as future IEEE 802.11 standards) modify packet preambles. For example, based on future modifications to packet preambles, some implementations of a STA may spend more time in a powered-down state when intermittently monitoring the wireless channel. Because a WLAN typically includes multiple STAs, power savings can be substantial.

[0021] 1 shows a system diagram of an exemplary wireless communication network 100. According to some aspects, the wireless communication network 100 may be an example of a wireless local area network (WLAN), such as a Wi-Fi network (also hereinafter referred to as WLAN 100). For example, the WLAN 100 may be a network implementing at least one of the IEEE 802.11 family of standards (as defined by the IEEE 802.11-2016 specification or amendments thereto, including, but not limited to, 802.11aa, 802.11ah, 802.11ad, 802.11aq, 802.11ay, 802.11ax, 802.11az, 802.11ba, and 802.11be). The WLAN 100 may include a number of WLAN devices, such as an access point (AP) 102 and multiple stations (STAs) 104 having wireless associations with the AP 102. Although only one AP 102 is illustrated, the WLAN 100 may also include multiple APs 102. The IEEE 802.11-2016 standard defines an STA as an addressable unit. An AP is an entity that includes at least one STA and provides associated STAs with access over a wireless medium (WM) to access distribution services (such as another network, not shown). Thus, an AP includes STAs and a distribution system access function (DSAF). In the example of FIG. 1, the AP 102 may be connected to a gateway device (not shown) that provides connectivity to another network 140. The DSAF of the AP 102 may provide access between the STA 104 and the other network 140. Although the AP 102 is described as an access point using an infrastructure mode, in some implementations, the AP 102 may be a conventional STA operating as an AP. For example, the AP 102 may be an STA capable of operating in a peer-to-peer mode or an independent mode. In some other examples, the AP 102 may be a software AP (SoftAP) running on a computer system.

[0022] Each of the STAs 104 may also be referred to as a mobile station (MS), mobile device, mobile handset, wireless handset, access terminal (AT), user equipment (UE), subscriber station (SS), or subscriber unit, among other possible examples. The STAs 104 may represent a variety of devices, such as a mobile phone, a personal digital assistant (PDA), other handheld device, netbook, notebook computer, tablet computer, laptop, display device (e.g., a TV, computer monitor, navigation system, among others), music or other audio or stereo device, remote control device ("remote"), printer, kitchen appliance or other household appliance, key fob (e.g., for a passive keyless entry and start (PKES) system), among other possible examples.

[0023] A single AP 102 and the associated set of STAs 104 may be referred to as a basic service set (BSS) managed by the respective AP 102. FIG. 1 additionally shows an example coverage area 108 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) and to other devices by a basic service set identifier (BSSID), which may be the medium access control (MAC) address of the AP 102. The AP 102 periodically broadcasts a beacon containing the BSSID to enable any STAs 104 within wireless range of the AP 102 to establish or maintain a respective communication link 106 (also referred to hereinafter as a “Wi-Fi link”) with the AP 102. For example, the beacon may include identification of the primary channel used by the respective AP 102, as well as a timing synchronization function for establishing or maintaining timing synchronization with the AP. The AP 102 may provide various STAs 104 in the WLAN with access to an external network (such as network 140) via respective communication links 106. To establish a communication link 106 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 (e.g., the 2.4 GHz, 5 GHz, 6 GHz, or 60 GHz bands). To perform passive scanning, the STAs 104 listen for beacons, which are transmitted by the respective APs 102 at periodic time intervals called target beacon transmission times (TBTTs) (measured in time units (TUs), where one TU may equal 1024 microseconds (μs)). To perform active scanning, the STAs 104 generate probe requests and transmit them continuously on each channel to be scanned, listening for probe responses from the APs 102.Each STA 104 may be configured to perform authentication and association operations to identify or select an AP 102 to associate with based on scan information obtained through passive or active scanning and establish a communication link 106 with the selected AP 102. The AP 102 may assign an association identifier (AID) to the STA 104 in accomplishing the association operation, and the AP 102 uses the association identifier (AID) to track the STA 104.

[0024] 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 from among multiple APs 102 that together form an extended service set (ESS) that includes multiple connected BSSs. An extended network station associated with a 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. Thus, a STA 104 may be covered by more than one AP 102 and may associate with different APs 102 at different times for different transmissions. Additionally, after associating with an AP 102, the STA 104 may also be configured to periodically scan its vicinity to find a more suitable AP 102 to associate with. For example, a STA 104 that is moving relative to its associated AP 102 may perform a “roaming” scan to find another AP 102 with more desirable network characteristics, such as a higher RSSI or reduced traffic load.

[0025] In some cases, the STAs 104 may form a network without involving the AP 102 or any other device other than the STAs 104 themselves. One example of such a network is an ad hoc network (or wireless ad hoc network). An ad hoc network may alternatively be referred to as a mesh network or a peer-to-peer (P2P) network. In some cases, the ad hoc network may be implemented within a larger wireless network, such as a WLAN 100. In such an implementation, the STAs 104 may be able to communicate with each other through the AP 102 using the communication link 106, but the STAs 104 can also communicate with each other directly via a direct wireless link 107. Additionally, two STAs 104 may communicate via the direct communication link 107 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 STAs 104 may be referred to as group owners (GOs) and may coordinate transmissions within the ad hoc network. Examples of direct wireless links 107 include Wi-Fi Direct connections, connections established by using Wi-Fi Tunneled Direct Link Setup (TDLS) links, and other P2P group connections.

[0026] The AP 102 and the STAs 104 may function and communicate (via their respective communication links 106) in accordance with the IEEE 802.11 family of standards (as defined by the IEEE 802.11-2016 specification or amendments thereto, including, but not limited to, 802.11aa, 802.11ah, 802.11aq, 802.11ad, 802.11ay, 802.11ax, 802.11az, 802.11ba, and 802.11be). These standards define WLAN radio and baseband protocols for the PHY layer and medium access control (MAC) layer. The AP 102 and the STAs 104 send and receive wireless communications (hereinafter also referred to as “Wi-Fi communications”) between each other in the form of Physical Layer Convergence Protocol (PLCP) Protocol Data Units (PPDUs).

[0027] Each frequency band may include multiple subbands or frequency channels. For example, PPDUs compliant with the IEEE 802.11n, 802.11ac, 802.11ax, and 802.11be standard amendments may be transmitted over the 2.4 GHz and 5 GHz bands, each of which is divided into multiple 20 MHz channels. Thus, these PPDUs are transmitted over physical channels with a minimum bandwidth of 20 MHz, but larger channels may be formed through channel bonding. For example, PPDUs compliant with the IEEE 802.11n, 802.11ac, 802.11ax, and 802.11be standard amendments may be transmitted over physical channels with bandwidths of 40 MHz, 80 MHz, 80+80 MHz, 160 MHz, 160+160 MHz, or 320 MHz by bonding together two or more 20 MHz channels, which may be allocated contiguously or non-contiguously. For example, IEEE 802.11n described the use of up to two channels (for a combined 40 MHz bandwidth) and specified a high-throughput (HT) transmission format. IEEE 802.11ac described the use of up to eight channels (for a combined 160 MHz bandwidth) and specified a very-high-throughput (VHT) transmission format. IEEE 802.11ax also supports up to a combined 160 MHz bandwidth (which may be a combination of up to eight channels, each 20 MHz wide). IEEE 802.11be may support up to a combined 320 MHz bandwidth (which may be a combination of up to 16 channels, each 20 MHz wide).

[0028] The APs 102 and STAs 104 in the WLAN 100 may transmit PPDUs over an unlicensed spectrum, which may be a portion of the 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, and the 900 MHz band. Some implementations of the APs 102 and STAs 104 described herein may also 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 may also be configured to communicate over other frequency bands, such as shared licensed frequency bands, in which multiple operators may have licenses to operate in the same or one or more overlapping frequency bands.

[0029] Each PPDU is a composite structure including a PHY preamble, a PHY header, and a payload in the form of a PLCP service data unit (PSDU). For example, a PSDU may include a PHY preamble and header (sometimes referred to as a PLCP preamble and header) and one or more MAC protocol data units (MPDUs). Information provided in the PHY preamble and header may be used by a receiving device to decode subsequent data in the PSDU. In cases where a PPDU is transmitted over a bonded channel, the preamble and header fields may be duplicated and transmitted in each of multiple component channels. The PHY preamble may be used for packet detection, automatic gain control, and channel estimation, among other uses. The format of the PHY header, the coding of the PHY header, and the information provided in the PHY header are based on the particular IEEE 802.11 protocol to be used to transmit the payload and typically include signaling fields (such as SIG-A and SIG-B fields) containing BSS and addressing information such as BSS color and STA ID.

[0030] FIG. 2 shows a diagram 200 illustrating an example STA 201 alternating between modes and power states when monitoring for packets over a wireless channel 211. The STA 201 may monitor the wireless channel 211 for packets transmitted by an AP 202. The AP 202 is an example of the AP 102 described with reference to FIG. 1. The STA 201 is an example of the STA 104 described with reference to FIG. 1. The STA 201 may alternating between a receive mode and a listen mode. A mode graph 205 illustrates an example of the STA 201 alternating between a receive mode 206 and a listen mode 208. In the receive mode 206, the packet detection component of the STA 201 may remain powered on to process packets received over the wireless channel 211. In some implementations, the packet detection component of the STA 201 may include one or more components of an RF front end, an ADC, and one or more components of a baseband processing unit. In listen mode 208, STA 201 may intermittently monitor wireless channel 211 for packets. For example, STA 201 may alternate between monitoring and not monitoring wireless channel 211 for packets, such as packets transmitted by AP 202. When monitoring wireless channel 211 in listen mode 208, STA 201 may configure packet detection components to a powered-on state. When not monitoring wireless channel 211 in listen mode 208, STA 201 may configure packet detection components to a powered-down state, as further described in FIGS. 4-6 . For example, in listen mode 208, STA 201 may alternate one or more components of the RF front end, ADC, and baseband processing unit between a powered-down state and a powered-on state.

[0031] Power state graph 213 illustrates an example of STA 201 alternating between a powered-up state and a powered-down state. Alternating between a powered-up state and a powered-down state is sometimes referred to as toggling between power states. Timeline 209 illustrates time progressing from left to right. As shown in FIG. 2, AP 202 may transmit a first packet 203 over wireless channel 211. STA 201 may enter receive mode 206 (at time=0) to receive and begin processing first packet 203. In receive mode 206, a packet detection component of STA 201 may remain powered-up to receive and process first packet 203 (see segment 212 of power state graph 213). After receiving first packet 203, STA 201 may switch to listen mode 208.

[0032] The STA 201 may enter a listen mode 208 (at time=7) in which the STA 201 may intermittently monitor the wireless channel 211 for packets. When monitoring the wireless channel 211 in the listen mode 208, the STA 201 may configure the packet detection component to a powered-up state (such as in segment 214 of the power state graph 213). For example, the STA 201 may provide power to the packet detection component to enter the powered-up state. When not monitoring the wireless channel 211 in the listen mode 208, the STA may configure the packet detection component to a powered-down state (such as in segment 215 of the power state graph 213). For example, as further described in FIGS. 4-6, the STA 201 may stop providing power to the packet detection component to enter the powered-down state. In some implementations, the duration of the powered-up state may be approximately the same as the duration of the powered-down time state. The power state graph 213 shows that the powered-down state lasts for a single time unit, and the powered-on state lasts for a single time unit. However, the powered-on and powered-down states may have any suitable duration. In some implementations, the duration of the powered-on state may differ from the duration of the powered-down time state. For example, the powered-down state may last for a single time unit, and the powered-on state may last for 1.5 time units. In some implementations, the STA 201 may alternate between the powered-on and powered-down states based on a configured duty cycle. For example, when the duration of the powered-on state is the same as the duration of the powered-down time state, the duty cycle may be a 50% duty cycle. Additional duty cycles are described with reference to FIG. 6. After detecting the second packet 204, the STA 201 may transition to a receive mode 206.

[0033] 2, the AP 202 may transmit (at time=16) a second packet 204 over the wireless channel 211. The STA 201 may detect the second packet 204 and may change from listen mode 208 to receive mode 206. The transition from listen mode 208 to receive mode 206 is further described in FIGS. 5 and 6. While in receive mode 206, the packet detection component may remain powered up to receive and process the second packet 204 (see segment 216 of power state graph 205). The STA 201 may remain in receive mode 206 until processing of the second packet 204 is complete. The STA 201 may then transition to listen mode (not shown), and the process may continue to repeat accordingly.

[0034] 3 shows a diagram 300 illustrating an example STA 201 alternating between modes and power states when monitoring for beacon frames over a wireless channel 211. The STA 201 may monitor the wireless channel 211 for beacon frames from the AP 202. The STA 201 may switch between a listen mode, a receive mode, and a sleep mode. A mode graph 305 illustrates an example of the STA 201 switching between a listen mode 208, a receive mode 206, and a sleep mode 304. In the sleep mode 304, the STA 201 may enter a powered-down state in which the STA 201 ceases to provide power to packet detection components. The STA 201 may determine a duration for the sleep mode 304 based on the time interval by which the AP 202 broadcasts beacon frames over the wireless channel 211. In some implementations, the time interval may be indicated in a delivery traffic interval message (DTIM) included in a beacon frame (such as the first beacon frame 303). The AP 202 may enter a sleep mode 304 between the beacon frame and "wake up" into a temporal listen mode 208 to detect the next beacon frame. If a beacon frame is detected during the listen mode 208, the STA 201 may enter a receive mode 206 in which the STA 201 processes the beacon frame.

[0035] Power state graph 313 illustrates an example of STA 201 alternating between a powered-up state and a powered-down state. Timeline 309 illustrates time progressing from left to right. As illustrated, STA 201 may enter listen mode 208 in which STA 201 intermittently monitors the wireless channel for beacon frames. In listen mode 208, STA 201 may alternate the packet detection component between a powered-up state and a powered-down state. During the powered-up state, STA 201 may provide power to the packet detection component and may monitor the wireless channel 211. During the powered-down state, STA 201 may stop providing power to the packet detection component and may stop monitoring the wireless channel 211, as further described in FIGS. 4-6.

[0036] 3, the AP 202 may transmit a first beacon frame 303 over the wireless channel 211. The STA 201 may detect the first beacon frame 303 and may enter a receive mode 206. During the receive mode 206, the STA 201 may remain powered on to process the first beacon frame 303.

[0037] As shown in FIG. 3, the STA 201 may enter a sleep mode 304. During the sleep mode 304, the STA 201 may configure its packet detection components to a powered-down state. The duration of the sleep mode 304 may depend on the time interval at which the AP 202 broadcasts a beacon frame over the wireless channel 211. The STA 201 may wake up from the sleep mode 304 and enter a listen mode 208. As shown in FIG. 3, the AP 202 may transmit a second beacon frame 312. The STA 201 may detect the second beacon frame 312 and enter a receive mode 206 during which the STA 201 may process the second beacon frame 312.

[0038] 4 is a block diagram illustrating an example STA 201 including a power state controller 404 that may control the power state of the STA 201. The STA 201 may include the power state controller 404, an RF front end 406, an ADC 408, and a baseband processing unit 410. As described in FIGS. 2 and 3, the RF front end 406, the ADC 408, and the baseband processing unit 410 may be referred to as packet detection components. The power state controller 404 may be communicatively coupled to the RF front end 406, the ADC 408, and the baseband processing unit 410. The RF front end 406 may include an RF amplifier (RFA) 416, such as a low-noise amplifier. The RF front end 406 may also include a mixer 414, a filter 412, and a synthesizer and phase-locked loop (PLL) 418. The ADC 408 may convert analog radio information into digital information associated with packets. The baseband processing unit 410 may process the digital information using digital processing components such as various filters and a baseband processor. For example, during listen mode, the baseband processing unit 410 may perform autocorrelation to detect a packet preamble. For example, the baseband processing unit 410 may perform autocorrelation to detect the STF of the packet preamble, as further described in FIGS. 5 and 6. As another example, during listen mode, the baseband processing unit may perform matched filtering to detect a packet preamble in the digital information.

[0039] The power state controller 404 may configure the packet detection components to a powered-up state and a powered-down state based on the operating mode of the STA. In some implementations, when the STA 201 is operating in listen mode, the power state controller 404 may configure one or more components of the RF front end 406 to a powered-down state. For example, the power state controller 404 may configure the RFA 416 of the RF front end 406 to a powered-down state. In some implementations, when the STA 201 is operating in listen mode, the power state controller 404 may configure the ADC 408 or one or more of its components (not shown) to a powered-down state. In some implementations, when the STA 201 is operating in listen mode, the power state controller 404 may configure the baseband processing unit 410 or one or more of its components (not shown) to a powered-down state.

[0040] In some implementations, the power state controller 404 may continuously provide power to the synthesizer and PLL 418 of the RF front end 406. For example, the synthesizer and PLL 418 may remain powered-on even when the RFA 416, mixer 414, and filter 412 are in a powered-down state. The power state controller 404 may also continuously provide power to some filters and components of the baseband processing unit 410 even when the RFA 416 or other components are in a powered-down state during listen mode. During sleep mode, the power state controller 404 may configure all components of the RF front end 406, the ADC 408, and all components of the baseband processing unit 410 to be in a powered-down state. During receive mode, the power state controller 404 may configure all components of the RF front end 406, the ADC 408, and all components of the baseband processing unit 410 to be in a powered-on state.

[0041] 5 illustrates an example of a listen mode alternating between a powered-on state and a powered-down state when monitoring for a PPDU. In some implementations, the STA 201 may detect and process a legacy PPDU 502 in listen mode. The legacy PPDU 502 may include a preamble including an L-STF 504, an L-LTF 506, and a legacy signal (L-SIG) field 508. The legacy PPDU 502 may also include a data field 510. In some implementations, the STA 201 may detect and process a mixed mode PPDU 511 in listen mode. The mixed mode PPDU 511 may include a legacy preamble as well as one or more next-generation preambles, such as one or more of an HT preamble, a VHT preamble, and an Extremely High Throughput (EHT) preamble. 5, in one example, a mixed mode PPDU 511 may include both a legacy preamble and an HT preamble and may include an L-STF 512, an L-LTF 514, an L-SIG 516, an HT-SIG 518, an HT-STF 520, an HT-LTF 522, and a data field 526. When a PPDU is transmitted over a wireless channel, the transmission of an L-STF (such as an L-STF 504 or an L-STF 512) and the transmission of other fields (such as an L-LTF 506 or an L-LTF 514) may have several durations as specified by the IEEE 802.11 standard. For example, the transmission of the L-STF 504 and the L-STF 512 may each have a duration of approximately 8 μs. In some implementations, the L-STF 504 and the L-STF 512 may each include STF information repeated 10 times over 8 μs, as further described in FIG. 6. In some implementations, L-LTF 506 and L-LTF 514 may each have a duration of approximately 8 μs. In some implementations, L-LTF 506 and L-LTF 514 may each include LTF information, such as configuration information, transmitted over 8 μs, as further described in FIG.

[0042] As shown in FIG. 5, the STA 201 may be operating in listen mode when a legacy PPDU 502 is transmitted over the wireless channel. The transmission of the legacy PPDU 502 may occur at any time during the listen mode. Thus, reception of the L-STF 504 may occur while the STA 201 is monitoring the wireless channel (powered-on state) or while the STA is not monitoring the wireless channel (powered-down state). To avoid missing the L-STF 504, the STA 201 may alternate between monitoring (powered-on state) and not monitoring (powered-down state) using a duty cycle that enables detection of the L-STF 504 within 8 μs of the L-STF 504 transmission. For example, in some implementations, the STA 201 may be capable of detecting the L-STF 504 via autocorrelation within at least two power state cycles (described further in FIG. 6), where the power state cycle includes a powered-on state and a powered-down state having a duration based on the duty cycle. In some implementations, the number of power state cycles to detect the L-STF 504 may depend on the RSSI associated with the legacy PPDU 502. For example, when the RSSI is greater than a first RSSI threshold, the STA 201 may detect the L-STF 504 within two power state cycles. As a non-limiting example, the first RSSI threshold may be approximately −85 dBm. The STA 201 may detect the L-STF 504 within more power state cycles when the RSSI is less than approximately −85 dBm. In some implementations, the number of power state cycles to detect the L-STF 504 may also depend on a channel condition metric (such as signal-to-noise ratio or channel congestion) or other suitable metric. For example, the STA 201 may detect the L-STF 504 within two power state cycles when the signal-to-noise ratio (SNR) is less than the SNR threshold and within more power state cycles when the SNR is greater than the SNR threshold. Additional details about detecting a packet preamble are provided in the description of FIG. 6.

[0043] The power graph 531 shows that the STA 201 alternates its packet detection components between a powered-up state and a powered-down state to detect the L-STF 504 or the L-STF 512. The STA 201 may alternate between the powered-up state and the powered-down state based on a duty cycle. According to the power graph 531, the STA 201 may be operating in a first powered-up state 537 in the listen mode 208. The timing line 534 shows that the STA 201 may receive at least a portion of the L-STF 504 during the first powered-up state 537. During the first powered-up state 537, the STA 201 monitors the wireless channel when the L-STF 504 (or L-STF 512) is received. While the following example describes receiving the L-STF 504 of a legacy PPDU 502, similar steps may be performed to receive the L-STF 512 of a mixed mode PPDU 511. In some implementations, as further described in FIG. 6, the STA 201 may detect the L-STF 504 if the STA 201 has sufficient time in a power-on state to detect at least two repetitions of the STF information in the L-STF 504. As shown in FIG. 5, the STA 201 may receive the L-STF 504 without having sufficient time in the first power-on state 537 to detect the L-STF 504 (e.g., by detecting two repetitions of the STF information via autocorrelation). As shown, without having detected the L-STF 504, the STA 201 may switch to a power-down state 538 in accordance with a duty cycle, and thus the STA 201 may stop monitoring the wireless channel until the next power-on state. During the second power-on state 540, the STA 201 may resume operation to monitor the wireless channel for preamble information (e.g., the L-STF 504). In the second power-up state 540, the STA 201 may detect the L-STF 504 (such as by detecting two repetitions of the STF information via autocorrelation). After detecting the L-STF 504, the STA 201 may switch to the receive mode 206 to process the legacy PPDU 502 in the power-up state.In some implementations, the STA 201 may detect the L-STF 504 by detecting any suitable number of repetitions of the STF information of the L-STF 504 in any suitable number of power-on states. The number of repetitions of the STF and the number of power-on states for detecting the L-STF 504 may depend on the particular packet detection technique (such as autocorrelation).

[0044] In some implementations, the STA 201 may determine whether to alternate between a powered-on state and a powered-down state during listen mode depending on the RSSI associated with a packet (such as a legacy PPDU 502 or a mixed-mode PPDU 511). For example, if the RSSI is greater than an RSSI threshold (such as -85 dBM), the STA 201 may alternate between a powered-on state and a powered-down state during listen mode. As another example, if the RSSI is less than a first RSSI threshold (such as -60 dBM) and greater than a second RSSI threshold (such as -85 dBM), the STA 201 may alternate between a powered-on state and a powered-down state during listen mode. However, if the RSSI is less than the second RSSI threshold (-85 dBM), the STA 201 may remain in the powered-on state throughout listen mode.

[0045] FIG. 6 illustrates example operations, timing, and power states for detecting a packet preamble 602 of a PPDU 600 in listen mode. The packet preamble 602 may include an L-STF 604, an L-LTF 606, and other information 603 (such as a packet payload). When a PPDU is transmitted over a wireless channel, the transmission of some fields may have some duration specified by a technical standard, such as the IEEE 802.11 standard. For example, the transmission of the L-STF 604 may have a duration of approximately 8 μs. In some implementations, the L-STF 604 may include STF information (such as an OFDM symbol) that is repeated 10 times over 8 μs, as shown in FIG. 6. In some implementations, the transmission of the L-LTF 606 may have a duration of approximately 8 μs. In some implementations, the L-LTF 606 may include LTF information, including a cyclic prefix 605, an OFDM symbol C1 607, and an OFDM symbol C2 609. The LTF information may be transmitted over 8 μs, as shown in FIG.

[0046] In the listen mode, the STA 201 may switch between monitoring the wireless channel for the PPDU 600 and not monitoring the wireless channel. The operation for monitoring the wireless channel may include at least one radio and data path settling operation. The radio and data path settling operation may power up an RF front end (such as the RF front end 406) after a power-down state. The radio and data path settling operation may also allow the radio and data paths in the RF front end to settle and be ready to perform additional operations for monitoring the wireless channel. The monitoring operation may also include at least one autocorrelation operation to detect the L-STF 604 of the PPDU 600 (e.g., by detecting a repetition of the STF information included therein). The operation for not monitoring the wireless channel may include an operation for configuring a packet detection component to a power-down state. In the listen mode, the STA 201 may switch between monitoring the wireless channel and not monitoring the wireless channel until a packet preamble, such as the L-STF 604 of the packet preamble 602, is detected. When the STA 201 detects the L-STF 604, the STA 201 may perform operations to prepare to process the L-LTF 606. In some implementations, these operations may include a gain change operation and a coarse timing operation. The gain change operation may change the gain of an amplifier in the RF front end (such as the RFA 416) to improve the strength or amplitude of the received signal associated with the PPDU 600 for further processing. The gain change operation may be followed by a coarse timing operation. The coarse timing operation may adjust the coarse timing of the RF front end 406 to align the frame with the symbol boundary of the L-LTF 606.

[0047] As shown in FIG. 6 , an exemplary operation sequence 620 may include operations for a listen mode. The operation sequence 620 may begin with an operation to monitor the wireless channel for the PPDU 600. For example, the operation sequence 620 may begin with a first radio and data path settling operation 610 and a first autocorrelation operation 612. In some implementations, the STA 201 may detect the L-STF 604 if an autocorrelation operation (such as the first autocorrelation operation 612) begins after receiving the L-STF 604. In the example shown in FIG. 6 , the timing line 630 indicates that the STA 201 started the first autocorrelation operation 612 before receiving the L-STF 604. Thus, in the example shown in FIG. 6 , the STA 201 did not detect the L-STF 604. The operation sequence 620 may continue with an operation whereby the STA 201 stops monitoring the wireless channel. For example, the operation sequence 620 may perform a power-down operation 618 to cease monitoring the wireless channel. After the power-down operation 618, the STA 201 may resume monitoring the wireless channel. For example, the STA 201 may perform a second radio and data path settling operation 611 and a second autocorrelation operation 613. During the operation sequence 620, after receiving the L-STF 604, the STA 201 may detect the L-STF 604 by performing the second autocorrelation operation 613. In some implementations, the second autocorrelation operation 613 may detect two repetitions of STF information in the L-STF 604. After detecting the L-STF 604, the STA 201 may perform an operation to prepare to process the L-LTF 606. During the operation sequence 620, the STA 201 may perform a gain change operation 614 and a coarse timing operation 616 to prepare to process the L-LTF 606. After preparing the L-LTF 606, the STA 201 may switch to a receive mode. In receive mode, the STA 201 may perform operations to process the L-LTF 606 and the remainder of the PPDU 600.

[0048] The listen mode and receive mode operations may have associated power states. When monitoring the wireless channel in the listen mode, the power state controller 404 of the STA 201 may configure the packet detection component to a powered-on state. When the STA 201 stops monitoring the wireless channel, the power state controller 404 may configure the packet detection component to a powered-down state. As shown in FIG. 6, an exemplary power graph 608 illustrates power states associated with operations performed in the listen mode and receive mode. As shown in operation sequence 620, the listen mode may include a first radio and data path settling operation 610. The power state controller 404 may provide power to the packet detection component to enter a powered-on state for the first radio and data path settling operation 610, as shown in the power graph 608. The power state controller 404 may keep the packet detection component in a powered-on state for a first autocorrelation operation 612, as shown in the power graph 608. After monitoring the wireless channel, the STA 201 may stop monitoring the wireless channel. To stop monitoring the wireless channel, the power state controller 404 may perform a power-down operation 618. For the power-down operation 618, the power state controller 404 may stop providing power to the packet detection component to enter a power-down state, as shown in the power graph 608. The STA 201 may resume monitoring the wireless channel by performing a second radio and data path settling operation 611. For the second radio and data path settling operation 611, the power state controller 404 may provide power to the packet detection component to enter a power-on state. The power state controller 404 may keep the packet detection component in a power-on state for a second autocorrelation operation 613, a gain change operation 614, and a coarse timing operation 616, as shown in the power graph 608. As shown in the power graph 608, the packet detection component may remain in a power-on state throughout the receive mode.

[0049] Operation in listen mode may involve timing aspects related to the PPDU. For example, the PPDU may have one or more transmission times specified in the IEEE 802.11 standard. As shown in FIG. 6 , the L-STF 604 may be transmitted within 8 μs. In some implementations, the listen mode operation can detect the L-STF 604 within 8 μs. The listen mode operation may include an operation for monitoring the wireless channel, an operation for not monitoring the wireless channel, and an operation for preparing the L-LTF. As shown in FIG. 6 , the operation for monitoring the wireless channel may include a first radio and data path settling operation 610 and a first autocorrelation operation 612. In some implementations, the first radio and data path settling operation 610 may have a duration of 1.2 μs, and the first autocorrelation operation 612 may have a duration of 1.6 μs. Thus, the duration for monitoring the wireless channel may be 2.8 μs (1.2 μs + 1.6 μs). As shown in FIG. 6, the STA 201 may stop monitoring the wireless channel by performing a power-down operation 618. In some implementations, the STA 201 may stop monitoring the wireless channel for 2.4 μs, as shown in operation sequence 620. Therefore, the duration of the operations for both monitoring and not monitoring the wireless channel may be 5.2 μs (2.4 μs + 2.8 μs). In this example, the duty cycle for the listen mode may be 46% (2.4 / 5.2). In some implementations, after detecting the L-STF 604, the STA 201 may perform operations to prepare to process the L-LTF 606. For example, the STA 201 may perform a gain change operation 614 and a coarse timing operation 616 to prepare to process the L-LTF 606. In some implementations, as shown in operation sequence 620, the gain change operation 614 may have a duration of 1.2 μs, and the coarse timing operation 616 may have a duration of 1.6 μs. Therefore, the operation to prime the L-LTF 606 may have a duration of 2.8 μs (1.2 μs+1.6 μs).The total duration for monitoring (2.8 μs), not monitoring (2.4 μs), and preparing the L-LTF 606 (2.8 μs) may be 8 μs (2.8 μs + 2.4 μs + 2.8 μs = 8 μs). Because the total duration of listen mode operation is 8 μs, the STA 201 can detect the L-STF 604 within its 8 μs transmission time.

[0050] Another timing aspect of the listen mode relates to detecting the L-STF when monitoring the wireless channel. In some implementations, the STA 201 may perform an autocorrelation operation to detect the L-STF, such as by detecting a repetition of STF information associated with the L-STF. There may be a detection duration for detecting a portion of the STF information via autocorrelation. The detection duration may indicate how late into the autocorrelation operation the L-STF can be received and still be detected. As shown in FIG. 6, the STA 201 may have a detection duration 625 for detecting a portion of the L-STF 604 (such as a portion of one repetition of the STF information). In some implementations, the detection duration 625 may be 0.4 μs. In FIG. 6, the arrival deadline 624 indicates the latest time the L-STF 604 can arrive and be detected by the first autocorrelation operation 612. 6, timing line 630 shows that L-STF 604 arrives after arrival deadline 624, and therefore, L-STF 604 is not detected. If L-STF 604 had arrived before arrival deadline 624, STA 201 may have detected L-STF 604. In some implementations, detection duration 625 may affect how long STA 201 stops monitoring the wireless channel. For example, if detection duration 625 is longer, the duration of power down operation 618 may be shortened to ensure that STA 201 can detect L-STF 604 within 8 μs.

[0051] Another timing aspect of listen mode relates to coarse timing. In some implementations, the STA 201 may perform a coarse timing operation when preparing to process an L-LTF. For example, as shown in FIG. 6, the STA 201 may perform a coarse timing operation 616 when preparing to process an L-LTF 606. The coarse timing deadline may indicate the latest time at which the STA 201 can complete the coarse timing operation and still be ready to process the L-LTF. If the coarse timing operation is not completed by the coarse timing deadline, the STA 201 may not be able to process the L-LTF. As shown in FIG. 6, timing line 627 indicates when the STA 201 receives the L-STF 606. The coarse timing deadline 626 indicates the latest time at which the STA 201 can complete the coarse timing operation 616 and still be able to process the L-LTF 606. In some implementations, the coarse timing deadline may be 0.4 μs after the L-LTF is received. In some implementations, the coarse timing deadline may affect how long the STA 201 may stop monitoring the wireless channel. For example, if the coarse timing deadline 626 is shorter, the duration of the power down operation 618 may be shortened to ensure that the STA 201 can detect the L-STF 604 within 8 μs.

[0052] In some implementations, the STA 201 may reduce the time spent in a powered-on state in listen mode. For example, the STA 201 reduces the time spent monitoring a wireless channel in a powered-on state. The operations for monitoring a wireless channel may include a radio and data path settling operation (such as a radio and data path settling operation 610) and an autocorrelation operation (such as a first autocorrelation operation 612). In some implementations, the autocorrelation operation may be replaced with a matched filtering operation. For example, rather than using autocorrelation to detect the L-STF, the STA 201 may use matched filtering to detect the L-STF. The matched filtering operation may use pattern matching to detect the L-STF. For example, the matched filtering operation may detect the L-STF by detecting a single repetition of STF information using pattern matching. In some implementations, the matched filtering operation may have a duration of 1 μs (compared to 1.6 μs for some implementations of an autocorrelation operation). In some implementations, the STA 201 may monitor the wireless channel by performing both radio and data path settling operations and matched filtering operations. The combined duration for the matched filtering operations (1 μs) and the radio and data path settling operations (1.2 μs) may be 2.2 μs. Therefore, the duration for monitoring the wireless channel may be 2.2 μs.

[0053] In some implementations, the STA 201 may also perform a coarse timing operation (such as the coarse timing operation 616) using a 1 μs matched filtering operation. When the STA 201 uses a 1 μs matched filtering operation for a coarse timing operation (such as for operation 616), the STA 201 may stop monitoring the wireless channel for 3.6 μs. Thus, the duration of operation for both monitoring and not monitoring the wireless channel may be 5.8 μs (3.6 μs + 2.2 μs). In this example, the duty cycle for the listen mode may be 62% (3.6 / 5.8).

[0054] In some implementations, a packet may include an L-STF of any suitable duration. For example, a packet may include a Greenfield preamble with an L-STF longer than 8 μs. The Greenfield preamble may be defined in the IEEE 802.11be standard. In some implementations, the Greenfield preamble may include an L-STF with a duration of 10 μs or longer. In some implementations, the STA 201 may perform powered-up state operation for 2.2 μs, as described in FIG. 6. Given a 10 μs L-STF and 2.2 μs powered-up state operation, the STA can remain in a powered-down state for 3.6 μs and still detect the L-STF 604 within 10 μs. Given a 10 μs L-STF and the timing of the powered-up state operation shown in FIG. 6, the STA 201 can achieve a 62% duty cycle. In some implementations, the duty cycle may depend, at least in part, on the duration of the L-STF and the speed of the operation to detect the L-STF.

[0055] 7 shows a process 700 for wireless communication in a WLAN, including example operations performed by an apparatus of a STA. Process 700 may be performed by a wireless communication device, such as wireless communication device 800 or electronic device 1000, described with reference to FIGS. 8 and 10, respectively. In some implementations, process 700 may be performed by a wireless communication device operating as or within an STA, such as one of the STAs 104, 201, and 904 described with reference to FIGS. 1, 2, 3, and 9B.

[0056] At block 710, the apparatus of the first WLAN device may alternate one or more components of the first WLAN device between a powered-down state and a powered-on state while the first WLAN device is in listen mode.

[0057] At block 720, the apparatus may receive packet preamble information from the second WLAN device while in a powered-on state.

[0058] 8 shows a block diagram of an example wireless communication device 800. In some implementations, the wireless communication device 800 may be an example of a device for use in a STA, such as one of the STAs 104 or 201 described herein. In some implementations, the wireless communication device 800 may be an example of a device for use in an AP, such as the AP 102 described herein. The wireless communication device 800 may be generally referred to as an apparatus or a wireless communication device. The wireless communication device 800 is capable of transmitting (or outputting for transmission) and receiving wireless communications (e.g., in the form of wireless packets). For example, the wireless communication device 800 may be configured to transmit and receive packets in the form of PPDUs and MPDUs that comply with the IEEE 802.11 standards as defined by the IEEE 802.11-2016 specification or amendments thereto, including, but not limited to, 802.11ah, 802.11ad, 802.11ay, 802.11ax, 802.11az, 802.11ba, and 802.11be, in addition to future 802.11 standards.

[0059] The wireless communication device 800 can be or include a chip, system-on-chip (SoC), chipset, package, or device that includes one or more modems 802, such as Wi-Fi (IEEE 802.11 compliant) modems. In some implementations, the one or more modems 802 (collectively “modems 802”) additionally include a WWAN modem (e.g., a 3GPP 4G LTE or 5G compliant modem). In some implementations, the wireless communication device 800 also includes one or more radios 804 (collectively “radios 804”). In some implementations, the wireless communication device 800 further includes one or more processors, processing blocks, or processing elements (collectively “processor(s) 806”) and one or more memory blocks or elements (collectively “memory 808”).

[0060] The modem 802 may include an intelligent hardware block or device, such as, for example, an application specific integrated circuit (ASIC), among other possible examples. The modem 802 is generally configured to implement a PHY layer. For example, the modem 802 is configured to modulate packets and output the modulated packets to the radio 804 for transmission over a wireless medium. The modem 802 is similarly configured to obtain modulated packets received by the radio 804 and demodulate the packets to provide demodulated packets. In addition to a modulator and a demodulator, the modem 802 may further include digital signal processing (DSP) circuitry, an automatic gain control (AGC), a coder, a decoder, a multiplexer, and a demultiplexer. For example, while in a transmit mode, data obtained from the processor 806 is provided to the coder, which encodes the data to provide coded bits. The coded bits are mapped to points in a modulation constellation (using a selected MCS) to provide modulated symbols. The modulated symbols are then coded into a number N SS The number of spatial streams or N STSThe modulated symbols in each spatial or space-time stream may be multiplexed, transformed via an inverse fast Fourier transform (IFFT) block, and then provided to DSP circuitry for Tx windowing and filtering. The digital signal may be provided to a digital-to-analog converter (DAC). The resulting analog signal may be provided to a frequency upconverter and ultimately to the radio 804. In an implementation involving beamforming, the modulated symbols in each spatial stream are precoded via a steering matrix before being provided to the IFFT block.

[0061] During receive mode, the digital signal received from the radio 804 is provided to DSP circuitry, which is configured to acquire the received signal, e.g., by detecting the presence of a signal and estimating an initial timing and frequency offset. The DSP circuitry is further configured to digitally condition the digital signal, e.g., using channel (narrowband) filtering, analog impairment adjustment (e.g., to correct I / Q imbalance), and finally applying a digital gain to obtain a narrowband signal. The output of the DSP circuitry may be provided to an AGC, which is configured to use information extracted from the digital signal, e.g., in one or more received training fields, to determine an appropriate gain. The output of the DSP circuitry is also coupled to a demodulator, which is configured to extract modulated symbols from the signal and, e.g., calculate a log-likelihood ratio (LLR) for each bit position of each subcarrier in each spatial stream. The demodulator may be coupled to a decoder, which may be configured to process the LLRs to provide decoded bits. The decoded bits from all of the spatial streams are provided to a demultiplexer for demultiplexing, which may be descrambled and provided to the MAC layer (processor 806) for processing, evaluation, or interpretation.

[0062] The radio 804 generally includes at least one radio frequency (RF) transmitter (or “transmitter chain”) and at least one RF receiver (or “receiver chain”), which may be combined into one or more transceivers. For example, the RF transmitter and RF receiver may each include various DSP circuitry, including at least one power amplifier (PA) and at least one low-noise amplifier (LNA). The RF transmitter and RF receiver may in turn be coupled to one or more antennas. For example, in some implementations, the wireless communication device 800 may include or be coupled to multiple transmit antennas (each with a corresponding transmit chain) and multiple receive antennas (each with a corresponding receive chain). Symbols output from the modem 802 are provided to the radio 804, which transmits the symbols via the coupled antenna. Similarly, symbols received via the antennas are obtained by the radio 804, which provides the symbols to the modem 802. In some implementations, the radio 804 and one or more antennas may form one or more network interfaces (sometimes referred to as "interfaces").

[0063] The processor 806 may include, for example, an intelligent hardware block or device, such as a processing core, processing block, central processing unit (CPU), microprocessor, microcontroller, digital signal processor (DSP), application specific integrated circuit (ASIC), programmable logic device (PLD) such as 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 806 processes information received through the radio 804 and modem 802 and processes information to be output through the modem 802 and radio 804 for transmission over a wireless medium. For example, the processor 806 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 frame coding and decoding, spatial multiplexing, space-time block coding (STBC), beamforming, and OFDMA resource allocation, among other operations or techniques. In some implementations, the processor 806 may generally control the modem 802 to cause the modem to perform the various operations described above.

[0064] The memory 808 may include a tangible storage medium, such as a random access memory (RAM) or a read-only memory (ROM), or a combination thereof. The memory 808 may also store non-transitory processor or computer-executable software (SW) code, including instructions that, when executed by the processor 806, cause the processor to perform various operations described herein for wireless communication, including generating, transmitting, receiving, and interpreting MPDUs, frames, or packets. For example, various functions of the components disclosed herein, or various blocks or steps of the methods, operations, processes, or algorithms disclosed herein, may be implemented as one or more modules of one or more computer programs.

[0065] In some implementations, the wireless communication device 800 may include a power state controller (not shown). The power state controller may be similar to the power state controller 404 described with reference to FIG. 4 and may perform any of the operations for controlling power supplies described herein. In some implementations, the power state controller may be implemented by the processor 806 and the memory 808. The memory 808 may include computer instructions executable by the processor 806 to implement the functionality of the power state controller. Any of this functionality may be implemented partially (or fully) in hardware or on the processor 806.

[0066] In some implementations, the processor 806 and memory 808 of the wireless communication device 800 may be referred to as a processing system. A processing system may generally refer to a system or set of machines or components that receives input, processes the input, and generates a set of outputs (e.g., that may be passed to other systems or components of one of the STAs 104 or one of the APs 102). In some implementations, the processing system may include the processor 806, the memory 808, and one or more other components of the wireless communication device 800, such as the modem 802.

[0067] In some implementations, the processing system of the STA 104 may interface with other components of the STA 104, process information (such as input or signals) received from other components, output information to other components, and so on. For example, a chip or modem of the STA 104 (such as the wireless communication device 800) may include a processing system and one or more interfaces. The one or more interfaces may include a first interface for receiving or acquiring information and a second interface for outputting, transmitting, or providing information. In some cases, the first interface may refer to an interface between the processing system of the chip or modem and a receiver, such that the STA 104 may receive information or signal input and information may be passed to the processing system. In some cases, the second interface may refer to an interface between the processing system of the chip or modem and a transmitter, such that the STA 104 may transmit information output from the chip or modem. One skilled in the art will readily recognize that the second interface may also acquire or receive information or signal input, and that the first interface may also output, transmit, or provide information.

[0068] In some implementations, the processing system of the AP 102 may interface with other components of the AP 102, process information (such as input or signals) received from other components, output information to other components, and so on. For example, a chip or modem of the AP 102 (such as the wireless communication device 800) may include a processing system, a first interface for receiving or acquiring information, and a second interface for outputting, transmitting, or providing information. In some cases, the first interface may refer to an interface between the processing system of the chip or modem and a receiver, such that the AP 102 may receive information or signal input and the information may be passed to the processing system. In some cases, the second interface may refer to an interface between the processing system of the chip or modem and a transmitter, such that the AP 102 may transmit information output from the chip or modem. Those skilled in the art will readily recognize that the second interface may also acquire or receive information or signal input, and that the first interface may also output, transmit, or provide information.

[0069] 9A shows a block diagram of an example AP 902. For example, the AP 902 may be an example implementation of the AP 102 described herein. The AP 902 includes a wireless communication device 910. For example, the wireless communication device 910 may be an example implementation of the wireless communication device 800 described with reference to FIG. 8. The AP 902 also includes multiple antennas 920 coupled to the wireless communication device 910 for transmitting and receiving wireless communications. In some implementations, the AP 902 additionally includes an application processor 930 coupled to the wireless communication device 910 and a memory 940 coupled to the application processor 930. The AP 902 further includes at least one external network interface 950 that enables the AP 902 to communicate with a core network or a backhaul network to gain access to external networks, including the Internet. For example, the external network interface 950 may include one or both of a wired (e.g., Ethernet) network interface and a wireless network interface (such as a WWAN interface). Some of the above-mentioned components may communicate directly or indirectly with some other of the components via at least one bus. The AP 902 further includes a housing that encloses the wireless communication device 910, the application processor 930, the memory 940, and at least a portion of the antenna 920 and the external network interface 950.

[0070] 9B shows a block diagram of an exemplary STA 904. For example, the STA 904 may be an exemplary implementation of the STA 104 or STA 201 described herein. The STA 904 includes a wireless communication device 915. For example, the wireless communication device 915 may be an exemplary implementation of the wireless communication device 800 described with reference to FIG. 8. The STA 904 may also include one or more antennas 925 coupled with the wireless communication device 915 for transmitting and receiving wireless communications. The STA 904 may additionally include an application processor 935 coupled with the wireless communication device 915 and a memory 945 coupled with the application processor 935. In some implementations, the STA 904 further includes a user interface (UI) 955 (e.g., a touchscreen or keypad) and a display 965, where the display 965 may be integrated with the UI 955 to form a touchscreen display. In some implementations, the STA 904 may further include one or more sensors 975, such as, for example, one or more inertial sensors, accelerometers, temperature sensors, pressure sensors, or altitude sensors. Some of the above-mentioned components can communicate directly or indirectly with other components via at least one bus. The STA 904 further includes a housing that encloses the wireless communication device 915, the application processor 935, the memory 945, and at least a portion of the antenna 925, the UI 955, and the display 965.

[0071] 10 shows a block diagram of an exemplary electronic device for implementing aspects of the present disclosure. In some implementations, the electronic device 1000 may be an AP (including any of the APs described herein), a range extender, a station (including any of the STAs described herein), or one of other electronic systems. The electronic device 1000 may include a processor 1002 (possibly including multiple processors, multiple cores, multiple nodes, implementing multithreading, etc.). The electronic device 1000 may also include a memory 1006. The memory 1006 may be system memory or any one or more of the possible implementations of a computer-readable medium described herein. In some implementations, the processor 1002 and the memory 1006 may be referred to as a processing system. The electronic device 1000 may also include a bus 1010 (such as PCI, ISA, PCI-Express, HyperTransport, InfiniBand, NuBus, AHB, AXI, etc.) and one or more network interfaces 1004 (sometimes referred to as “interfaces”), which may include at least one of a wireless network interface (such as a WLAN interface, a Bluetooth interface, a WiMAX interface, a ZigBee interface, a wireless USB interface, etc.) and a wired network interface (such as an Ethernet interface, a power line communication interface, etc.). In some implementations, the electronic device 1000 may support multiple network interfaces, each configured to couple the electronic device 1000 to different communication networks.

[0072] The electronic device 1000 may include a power state controller 404 that may perform operations to control power as described herein. In some implementations, the power state controller 404 may be distributed within the processor 1002 and the memory 1006. The power state controller 404 may perform some or all of the location aware steering operations described herein in this disclosure. In some implementations, the network interface 1004 may include an RF front end 406, an ADC 408, and a baseband processing unit 410. In some implementations, the network interface may also include the power state controller 404.

[0073] The memory 1006 may include computer instructions executable by the processor 1002 to perform the functionality of the implementations described in Figures 1-10. Any of this functionality may be implemented partially (or fully) in hardware or on the processor 1002. For example, functionality may be implemented using an application-specific integrated circuit, in logic implemented in the processor 1002, in a co-processor on a peripheral device or card, etc. Furthermore, implementations may include fewer components or additional components not shown in Figure 10 (such as a video card, an audio card, additional network interfaces, peripheral devices, etc.). The processor 1002, memory 1006, and network interface 1004 are coupled to a bus 1010. Although illustrated as coupled to the bus 1010, the memory 1006 may be coupled to the processor 1002.

[0074] 1-10 and the operations described herein are examples intended to aid in understanding exemplary implementations and should not be used to limit possible implementations or to limit the scope of the claims. Some implementations may perform additional operations, may perform fewer operations, may perform operations in parallel or in a different order, or may perform some operations differently.

[0075] The above disclosure provides illustrations and descriptions, but is not intended to be exhaustive or to limit the aspects to the precise form disclosed. Modifications and variations may be made in light of the above disclosure or acquired from practice of the aspects. Although aspects of the present disclosure have been described with reference to various examples, any combination of aspects from any of the examples is within the scope of the present disclosure. The examples in this disclosure are provided for educational purposes. Alternatively, or in addition to other examples described herein, examples include any combination of the following implementation options:

[0076] Clause 1. One inventive aspect of the subject matter described in this disclosure may be embodied in a method for wireless communication performed by a device of a first AP in a WLAN. The method may include alternating one or more components of the first WLAN device between a powered-down state and a powered-on state while the first WLAN device is in a listen mode. The method may include receiving packet preamble information from a second WLAN device while in the powered-on state.

[0077] Clause 2. The method of clause 1, further comprising performing autocorrelation on the preamble information to detect a preamble of the packet.

[0078] Clause 3. The method of any one or more of clauses 1-2, wherein the first WLAN device remains in a powered-on state to perform autocorrelation on preamble information. The method further includes ceasing to alternate one or more components of the WLAN device between a powered-down state and a powered-on state during the listen mode in response to detecting a preamble of the packet based on the autocorrelation. The method further includes initiating a receive mode to process the packet.

[0079] Clause 4. The method of any one or more of clauses 1-3, wherein the preamble of the packet includes a number of repetitions of preamble information, the method further including detecting the preamble information by detecting one or more of the repetitions of the preamble information.

[0080] Clause 5. The method of any one or more of clauses 1-4, wherein the number of repetitions of the preamble information includes a number of repetitions of the STF information.

[0081] Clause 6. The method of any one or more of clauses 1-5, wherein the duration of the powered-down state and the duration of the powered-on state are based at least in part on a number of repetitions of preamble information and a duration of time for detection of a packet preamble.

[0082] Clause 7. The method of any one or more of clauses 1-6, wherein alternating one or more components between a powered-down state and a powered-on state includes alternating the one or more components between a powered-down state and a powered-on state according to a duty cycle.

[0083] Clause 8. The method of any one or more of clauses 1-7, wherein alternating one or more components of the first WLAN device between a powered-down state and a powered-on state is performed when the RSSI is greater than an RSSI threshold.

[0084] Clause 9. The method of any one or more of clauses 1-8, wherein alternating one or more components of the first WLAN device between a powered-down state and a powered-on state is performed when the RSSI is greater than a first RSSI threshold and less than a second RSSI threshold.

[0085] Clause 10. The method of any one or more of clauses 1-9, wherein the one or more components of the first WLAN device include at least one of one or more components of an RF front end, an ADC, and one or more components of a baseband processing unit.

[0086] Clause 11. The method of any one or more of clauses 1-10, further comprising performing matched filtering on the preamble information to detect the packet preamble.

[0087] Clause 12. The method of any one or more of clauses 1-11, wherein the first WLAN device remains powered on to perform matched filtering on the preamble of the packet.

[0088] Clause 13. Another inventive aspect of the subject matter described in this disclosure may be embodied in an apparatus of a first WLAN device for wireless communication. The apparatus of the first WLAN device may include a processor configured to alternate one or more components of the first WLAN device between a powered-down state and a powered-on state during a listen mode of the first WLAN device. The apparatus of the first WLAN device may include an interface configured to obtain packet preamble information from a second WLAN device during the powered-on state.

[0089] Clause 14. The apparatus of clause 13, wherein the processor is further configured to perform autocorrelation on the preamble information to detect a preamble of the packet.

[0090] Clause 15. The apparatus of any one or more of clauses 13-14, wherein the processor is further configured to: cease alternating one or more components of the first WLAN device between a powered-down state and a powered-on state during the listen mode in response to detecting a preamble of the packet based on the autocorrelation. The processor may be further configured to initiate a receive mode to process the packet.

[0091] Clause 16. The apparatus of any one or more of clauses 13-15, wherein the preamble of the packet includes a number of repetitions of preamble information, and wherein detecting the preamble includes detecting one or more of the repetitions of the preamble information.

[0092] Clause 17. The apparatus of any one or more of clauses 13-16, wherein the number of repetitions of the preamble information includes a number of repetitions of the STF information.

[0093] Clause 18. The device of any one or more of clauses 13-17, wherein the duration of the powered-down state and the duration of the powered-on state are based at least in part on a number of repetitions of preamble information and a duration of time for detection of a packet preamble.

[0094] Clause 19. The device of any one or more of clauses 13-18, wherein alternating one or more components between a powered-down state and a powered-on state includes alternating one or more components between a powered-down state and a powered-on state according to a duty cycle.

[0095] Clause 20. The apparatus of any one or more of clauses 13-19, wherein the interface is further configured to obtain an RSSI associated with the packet, and wherein alternating one or more components of the first WLAN device between a powered-down state and a powered-on state is performed in response to the RSSI being greater than an RSSI threshold.

[0096] Clause 21. The apparatus of any one or more of clauses 13-20, wherein the interface is further configured to obtain an RSSI associated with the packet, and wherein alternating one or more components of the first WLAN device between a powered-down state and a powered-on state is performed in response to the RSSI being greater than a first RSSI threshold and less than a second RSSI threshold.

[0097] Clause 22. The apparatus of any one or more of clauses 13-21, wherein the one or more components of the first WLAN device include at least one of one or more components of an RF front end, an ADC, and one or more components of a baseband processing unit.

[0098] Clause 23. The apparatus of any one or more of clauses 13-22, wherein the processor is further configured to perform matched filtering on one or more fields of the preamble information to detect a preamble of the packet.

[0099] Clause 24. Another inventive aspect of the subject matter described in this disclosure may be embodied in a non-transitory computer-readable medium storing instructions that, when executed by a processor of a first WLAN device, cause the first WLAN device to perform operations for communication in a WLAN. The operations may cause the first WLAN device to alternate one or more components of the first WLAN device between a powered-down state and a powered-on state while the first WLAN device is in a listen mode. The operations may cause the first WLAN device to obtain packet preamble information from a second WLAN device while in the powered-on state.

[0100] Clause 25. The non-transitory computer-readable medium of any one or more of clauses 1-12 and 24, wherein the instructions further cause the first WLAN device to perform autocorrelation on the preamble information to detect a preamble of the packet.

[0101] Clause 26. The non-transitory computer-readable medium of any one or more of clauses 1-12 and 24-25, wherein the first WLAN device remains in a powered-on state to perform autocorrelation on preamble information. The instructions further cause the first WLAN device to, in response to detecting a preamble of the packet based on the autocorrelation, cease alternating one or more components of the WLAN device between a powered-down state and a powered-on state while in a listen mode and initiate a receive mode to process the packet.

[0102] Clause 27. The non-transitory computer-readable medium of any one or more of clauses 1-12 and 24-26, wherein the preamble information includes a number of repetitions of a symbol. The instructions further cause the first WLAN device to detect the preamble information by detecting one or more of the repetitions of the symbol.

[0103] Clause 28. Another inventive aspect of the subject matter described in this disclosure may be embodied in an apparatus of a first WLAN device for wireless communication. The apparatus of the first WLAN device may include means for alternating one or more components of the first WLAN device between a powered-down state and a powered-on state while the first WLAN device is in a listen mode. The apparatus of the first WLAN device may include means for obtaining packet preamble information from a second WLAN device while in the powered-on state.

[0104] Clause 29. The apparatus of any one or more of clauses 1-12 and 28, further comprising means for performing autocorrelation on the preamble information to detect a preamble of the packet.

[0105] Clause 30. The apparatus of any one or more of clauses 1-12 and 28-29, wherein the first WLAN device remains in a powered-on state to perform autocorrelation on preamble information. The apparatus further includes means for, in response to detecting a preamble of the packet based on the autocorrelation, ceasing to alternate one or more components of the WLAN device between a powered-down state and a powered-on state during a listen mode and initiating a receive mode for processing the packet.

[0106] Another inventive aspect of the subject matter described in this disclosure may be implemented as a station apparatus or AP apparatus for wireless communication, which may include one or more interfaces and one or more processors configured to perform any one of the methods described above or functions described herein.

[0107] As used herein, a phrase referring to "at least one of" a list of items refers to any combination of those items, including single members. As an example, "at least one of a, b, or c" is intended to encompass a, b, c, ab, ac, bc, and abc.

[0108] The various exemplary logic, logic blocks, modules, circuits, and algorithmic processes described in connection with the implementations disclosed herein may be implemented as electronic hardware, computer software, or a combination of both. Interchangeability between hardware and software is generally described in terms of functionality and is shown in the various exemplary components, blocks, modules, circuits, and processes described throughout. Whether such functionality is implemented in hardware or software depends on the particular application and design constraints imposed on the overall system.

[0109] The hardware and data processing devices used to implement the various example logic, logic blocks, modules, and circuits described in connection with the aspects disclosed herein may be implemented or performed using general-purpose single-chip or general-purpose multi-chip processors, digital signal processors (DSPs), application-specific integrated circuits (ASICs), field-programmable gate arrays (FPGAs) or other programmable logic devices, discrete gate or transistor logic, discrete hardware components, or any combination thereof designed to perform the functions described herein. A general-purpose processor may be a microprocessor, or any conventional processor, controller, microcontroller, or state machine. A processor may also be implemented as a combination of computing devices, e.g., a combination of a DSP and a microprocessor, multiple microprocessors, one or more microprocessors in conjunction with a DSP core, or any other such configuration. In some implementations, particular processes and methods may be performed by circuitry specific to a given function.

[0110] In one or more aspects, the functions described may be implemented in hardware, digital electronic circuitry, computer software, firmware, or any combination thereof, including the structures disclosed herein and their structural equivalents. Implementations of the subject matter described herein may also be implemented as one or more computer programs, i.e., as one or more modules of computer program instructions encoded on a computer storage medium for execution by or to control the operation of a data processing apparatus.

[0111] If implemented in software, the functions may be stored on or transmitted over as one or more instructions or code on a computer-readable medium. The processes of a method or algorithm disclosed herein may be embodied in a processor-executable software module, which may reside on a computer-readable medium. Computer-readable media includes both computer storage media and communication media, including any medium that may enable a computer program to be transferred from one place to another. A storage medium may be any available medium that can be accessed by a computer. By way of example, and not limitation, such computer-readable media may include RAM, ROM, EEPROM, CD-ROM or other optical disk storage, magnetic disk storage or other magnetic storage devices, or any other medium that can be used to store desired program code in the form of instructions or data structures and that can be accessed by a computer. Also, any connection may be properly referred to as a computer-readable medium. As used herein, disk and disc include compact discs (CDs), laser discs, optical discs, digital versatile discs (DVDs), floppy disks, and Blu-Ray™ discs, where disks typically reproduce data magnetically and discs reproduce data optically using lasers. Combinations may also be included within the scope of computer-readable media. Additionally, operations of a method or algorithm may reside on machine-readable and computer-readable media, which may be embodied in a computer program product as one or any combination or set of code and instructions.

[0112] Various modifications to the implementations described in this disclosure may be readily apparent to those skilled in the art, and the general principles defined herein may be applied to other implementations without departing from the spirit or scope of the 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 and the principles and novel features disclosed herein.

[0113] Additionally, those skilled in the art will readily appreciate that the terms "upper" and "lower" may be used to simplify the description of the figures, indicate relative positions corresponding to the orientation of the figure on a suitably oriented page, and may not reflect the proper orientation of any device when implemented.

[0114] Some features described herein in the context of separate implementations may also be implemented in combination in a single implementation. Conversely, various features described in the context of a single implementation may also be implemented in multiple implementations separately or in any suitable subcombination. Moreover, features may be described as working in some combinations and may even be initially claimed as such, but one or more features from the claimed combination may, in some cases, be deleted from the combination, and the claimed combination may be directed to a subcombination or a variation of the subcombination.

[0115] Similarly, while operations are shown in the figures in a particular order, this should not be understood as requiring such operations to be performed in the particular order or sequential order shown, or that all of the illustrated operations be performed, to achieve desirable results. Further, the figures may generally depict one or more exemplary processes in the form of a flow diagram. However, other operations not shown may be incorporated into the generally depicted exemplary process. For example, one or more additional operations may be performed before, after, simultaneously with, or between any of the depicted operations. In some situations, multitasking and parallel processing may be advantageous. Moreover, the separation of various system components in the described implementations should not be understood as requiring such separation in all implementations, and it should be understood that the described program components and systems may generally be integrated together in a single software product or packaged in multiple software products. Additionally, other implementations are within the scope of the following claims. In some cases, the actions recited in the claims may be performed in a different order and still achieve desirable results. [Explanation of symbols]

[0116] 100 Wireless communication network, WLAN 102 Access Point (AP) 104 stations (STA) 106 Communication Links 107 Direct wireless link, direct communication link 108 coverage areas 140 other networks 201 STA 202 AP 203 First Packet 204 Second Packet 205 Mode graph, power status graph 206 Receive Mode 208 Listen Mode 209 Timeline 211 Wireless Channels 213 Power Status Graph 303 First beacon frame 304 Sleep Mode 305 Mode Graph 309 Timeline 312 Second Beacon Frame 313 Power Status Graph 404 Power State Controller 406 RF Front End 408 Analog-to-Digital Converter (ADC) 410 Baseband Processing Unit 412 filters 414 Mixer 416 RF Amplifier (RFA) 418 Synthesizers and Phase Locked Loops (PLLs) 502 Legacy PPDU 504 L-STF 506 L-LTF 508 Legacy Signal (L-SIG) Field 510 Data Fields 511 Mixed Mode PPDU 512 L-STF 514 L-LTF 516 L-SIG 518 HT-SIG 520HT-STF 522HT-LTF 526 Data Fields 531 Power Graph 534 Timing Line 537 First power-on state 538 Power Off State 540 Second Power-Up State 600 PPDU 602 Packet Preamble 603 Other Information 604 L-STF 605 Cyclic Prefix 606 L-LTF 607 OFDM symbol C1 608 Power Graph 609 OFDM symbol C2 610 First Radio and Data Path Settling Operation 611 Second Radio and Data Path Settling Operation 612 First Autocorrelation Operation 613 Second Autocorrelation Operation 614 Gain change operation 616 Coarse Timing Operation 618 Power-off operation 620 Operation Sequence 624 Arrival Deadline 625 Detection Duration 626 Rough Timing Deadline 627 Timing Line 630 Timing Line 800 Wireless Communication Devices 802 modem 804 Wireless 806 processor 808 memory 902 AP 904 STA 910 Wireless Communication Devices 915 Wireless Communication Devices 920 Antenna 925 Antenna 930 Application Processor 935 Application Processor 940 memory 945 memory 950 external network interface 955 User Interface (UI) 965 Display 975 Sensor 1000 Electronic Devices 1002 processor 1004 Network Interface 1006 memory 1010 Bus

Claims

1. 1. A method for wireless communication in a wireless local area network (WLAN), performed by a first WLAN device, comprising: during a listen mode, alternating one or more components of the first WLAN device between a listen mode powered-down state and a listen mode powered-on state of the first WLAN device according to a duty cycle; switching, by the first WLAN device, between the listen mode, the receive mode, and a sleep mode, the receive mode being a power-on state; performing autocorrelation on the preamble information to detect a preamble of the packet; receiving the preamble information of the packet from a second WLAN device during the power-on state of the listen mode; Equipped with the first WLAN device remains in the powered-on state in the listen mode to perform the autocorrelation on the preamble information, and the method further comprises: in response to detecting the preamble of the packet based on the autocorrelation, ceasing to alternate the one or more components of the first WLAN device between the powered-down state of the listen mode and the powered-on state of the listen mode; and initiating the receive mode for processing the packet. method.

2. a preamble of the packet including a number of repetitions of the preamble information, the method comprising: detecting the preamble information by detecting one or more of the repetitions of the preamble information. The method of claim 1.

3. 3. The method of claim 2, wherein the repetition of the preamble information a certain number of times comprises repetition of short training field (STF) information a certain number of times.

4. 3. The method of claim 2, wherein a duration of the powered-down state of the listen mode and a duration of the powered-up state of the listen mode are based at least in part on the number of repetitions of preamble information and a duration of time for detection of the preamble of the packet.

5. 2. The method of claim 1, wherein alternating the one or more components between the powered-down state of the listen mode and the powered-on state of the listen mode comprises alternating the one or more components between the powered-down state of the listen mode and the powered-on state of the listen mode in accordance with the duty cycle.

6. 2. The method of claim 1, wherein alternating the one or more components of the first WLAN device between the powered-down state of the listen mode and the powered-on state of the listen mode is performed when a received signal strength indicator (RSSI) is greater than an RSSI threshold.

7. 2. The method of claim 1, wherein alternating the one or more components of the first WLAN device between the powered-down state of the listen mode and the powered-on state of the listen mode is performed when an RSSI is greater than a first RSSI threshold and less than a second RSSI threshold.

8. The one or more components of the first WLAN device: one or more components of a radio frequency (RF) front end; Analog-to-Digital Converter (ADC), and including at least one of the one or more components of a baseband processing unit; The method of claim 1.

9. performing a matched filter process on the preamble information to detect the preamble of the packet. The method of claim 1 , further comprising:

10. 10. The method of claim 9, wherein the first WLAN device remains in the powered-on state of the listen mode to perform the matched filtering on the preamble of the packet.

11. An apparatus for a first WLAN device for wireless communication, comprising: during a listen mode, alternating one or more components of the first WLAN device between a listen mode powered-down state and a listen mode powered-on state of the first WLAN device according to a duty cycle; switching, by the first WLAN device, between the listen mode, the receive mode, and the sleep mode; configured to perform an autocorrelation on the preamble information to detect the packet preamble. A processor; an interface configured to obtain the preamble information of the packet from a second WLAN device during the power-on state of the listen mode; wherein the receive mode is a power-on state; The processor, in response to detecting the preamble of the packet based on the autocorrelation, ceasing to alternate the one or more components of the first WLAN device between the powered-down state of the listen mode and the powered-on state of the listen mode; and further configured to initiate the receive mode to process the packet. Device.

12. 12. The apparatus of claim 11, wherein the preamble of the packet includes a number of repetitions of the preamble information, and wherein detecting the preamble includes detecting one or more of the repetitions of the preamble information.

13. 13. The apparatus of claim 12, wherein the repetition of the preamble information a number of times comprises a repetition of short training field (STF) information a number of times.

14. 13. The apparatus of claim 12, wherein a duration of the powered-down state of the listen mode and a duration of the powered-on state of the listen mode are based at least in part on the number of repetitions of preamble information and a duration of time for detection of the preamble of the packet.

15. 12. The apparatus of claim 11, wherein alternating the one or more components between the powered-down state of the listen mode and the powered-on state of the listen mode comprises alternating the one or more components between the powered-down state of the listen mode and the powered-on state of the listen mode according to a duty cycle.

16. The interface, and further configured to obtain a received signal strength indicator (RSSI) associated with the packet, and wherein alternating the one or more components of the first WLAN device between the powered-down state of the listen mode and the powered-on state of the listen mode is performed in response to the RSSI being greater than an RSSI threshold.

12. The apparatus of claim 11.

17. The interface, and further configured to obtain a received signal strength indicator (RSSI) associated with the packet, and wherein alternating the one or more components of the first WLAN device between the powered-down state of the listen mode and the powered-on state of the listen mode is performed in response to the RSSI being greater than a first RSSI threshold and less than a second RSSI threshold.

12. The apparatus of claim 11.

18. The one or more components of the first WLAN device: one or more components of a radio frequency (RF) front end; Analog-to-Digital Converter (ADC), and including at least one of the one or more components of a baseband processing unit; 12. The apparatus of claim 11.

19. The processor, and performing matched filtering on one or more fields of the preamble information to detect a preamble of the packet.

12. The apparatus of claim 11.

20. A non-transitory computer-readable medium having stored thereon instructions, which when executed by a processor of a first wireless local area network (WLAN) device, cause the first WLAN device to: during a listen mode, alternating one or more components of the first WLAN device between a listen mode powered-down state and a listen mode powered-on state of the first WLAN device according to a duty cycle; switching, by the first WLAN device, between the listen mode, the receive mode, and a sleep mode, the receive mode being in a powered-on state; causing the first WLAN device to perform autocorrelation on preamble information to detect a packet preamble; obtaining the preamble information of the packet from a second WLAN device during the power-on state of the listen mode; the first WLAN device remains in the powered-on state in the listen mode to perform the autocorrelation on the preamble information, the instructions further including causing the first WLAN device to: in response to detecting the preamble of the packet based on the autocorrelation, ceasing to alternate the one or more components of the first WLAN device between the powered-down state of the listen mode and the powered-on state of the listen mode; and initiating a receive mode for processing the packet. Non-transitory computer-readable medium.

21. The preamble information includes a number of repetitions of a symbol, the instructions further including causing the first WLAN device to: detecting the preamble information by detecting one or more of the repetitions of the symbol.

21. The non-transitory computer-readable medium of claim 20.

22. An apparatus for a first WLAN device for wireless communication, comprising: means for alternating, during a listen mode, one or more components of the first WLAN device between a listen mode powered-down state and a listen mode powered-on state of the first WLAN device according to a duty cycle; means for switching, by the first WLAN device, between the listen mode, the receive mode, and the sleep mode, the receive mode being a power-on state; means for performing autocorrelation on the preamble information to detect a packet preamble; means for obtaining the preamble information of the packet from a second WLAN device during the power-on state of the listen mode; Equipped with the first WLAN device remains in the powered-on state in the listen mode to perform the autocorrelation on the preamble information, and the apparatus: means for ceasing to alternate the one or more components of the first WLAN device between the powered down state of the listen mode and the powered up state of the listen mode in response to detecting the preamble of the packet based on the autocorrelation; and and means for initiating the receive mode for processing the packet. Device.

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