Reducing listen mode power consumption of wireless local area network (WLAN) device

Abstract

To provide a method, a device, and a system for reducing power consumption.SOLUTION: In a system of a wireless communication network, a wireless station (STA) alternates between monitoring a wireless channel 211 for packets and not monitoring the wireless channel to reduce power consumption in a listen mode 208, and configures a packet detection component to be in a power-on state when monitoring the wireless channel for packets in a listen mode, and configures a packet detection component to be in a power-off state when not monitoring the wireless channel in the listen mode. During the power-on state of the listen mode, the STA detects a preamble of a packet transmitted over the wireless channel, and in response to detecting the packet preamble, switches from the listen mode to the receive mode to process the packet.SELECTED DRAWING: Figure 2

Description

Technical Field

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

[0002] This disclosure generally relates to the field of wireless communication and to reducing the power consumption of a wireless local area network (WLAN) device operating in listen mode.

Background Art

[0003] A wireless local area network (WLAN) can be formed by one or more wireless access points (APs) that provide a shared wireless communication medium for use by a plurality of client devices, sometimes referred to as wireless stations (STAs). The basic building block of a WLAN compliant with the Institute of Electrical and Electronics Engineers (IEEE) 802.11 standard family is a basic service set (BSS) managed by an AP. Each BSS is identified by a service set identifier (SSID) known to the AP. The AP periodically broadcasts beacon frames to enable other STAs within the 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 to seek packets or other information. When the STA detects a packet on the wireless channel, the STA may receive the packet and may perform operations for processing the packet. Since the STA monitors the wireless channel, detects a packet, and performs operations for receiving the packet, 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 a packet. When the STA does not anticipate communication via the wireless channel, the STA may operate in a sleep mode where the STA does not consume resources for monitoring the wireless channel.

Summary of the Invention

Means for Solving the Problems

[0005] Each of the systems, methods, and devices of the present disclosure has several inventive aspects, and no single one of those aspects alone bears the desirable attributes disclosed herein.

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

[0007] Another inventive aspect of the subject matter described in this disclosure can be implemented 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-off 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 preamble information of a packet from a second WLAN device during the powered-on state.

[0008] Another inventive aspect of the subject matter described in this disclosure can be implemented 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-off state and a powered-on state during a listen mode of the first WLAN device. The operations may cause the first WLAN device to obtain preamble information of a packet from a second WLAN device during the powered-on state.

[0009] Another inventive aspect of the subject matter described in this disclosure can be implemented 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-off 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 preamble information of a packet from a second WLAN device during the powered-on state.

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

[0011] 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 be apparent from the description, the drawings, and the claims. Note that the relative dimensions of the following figures may not be drawn to scale.

Brief Description of the Drawings

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DETAILED DESCRIPTION

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

[0014] For the purpose of explaining the 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 the present disclosure are based on wireless local area network (WLAN) communication according to the Institute of Electrical and Electronics Engineers (IEEE) 802.11 wireless standard. However, the aspects described can be implemented in any device, system, or network capable of transmitting and receiving radio frequency (RF) signals according to one or more of the other known signals used for communication within a wireless network, cellular network, or Internet of Things (IoT) network, such as the IEEE 802.11 standard, Bluetooth® standard, code division multiple access (CDMA), frequency division multiple access (FDMA), time division multiple access (TDMA), Global System for Mobile Communications (GSM) for mobile communication, GSM / general packet radio service (GPRS), enhanced data GSM environment (EDGE), terrestrial trunked radio (TETRA), wideband CDMA (W-CDMA), evolution data optimized (EV-DO), 1xEV-DO, EV-DO Rev A, EV-DO Rev B, 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 3G technology, 4G technology, 5G technology, 6G technology, or further implementations thereof.

[0015] A wireless local area network (WLAN) in a house, apartment, enterprise, or other type of environment may include two or more WLAN devices. The WLAN may include one or more access points (APs) and one or more stations (STAs). An AP is a type of STA that performs a distribution system access function in a WLAN. For the sake of brevity, this disclosure refers to a WLAN device that can operate as either an AP or an STA. An AP may provide wireless access to STAs located within the coverage area of the AP. STAs may include various types of WLAN devices such as mobile phones, laptops, gaming systems (including virtual reality systems and extended 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 via 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). Briefly, the first and second BSSs may sometimes be referred to as the AP's first frequency band and the AP's second frequency band, respectively.

[0016] In a WLAN, a STA can utilize various operation modes including a listen mode, a receive mode, and a sleep mode. In the listen mode, the STA can continuously monitor the wireless channel for packets. To continuously monitor the wireless channel in the listen mode, the STA may continuously supply power to a component that detects packets on the wireless channel. When the STA detects a packet, the STA may enter the 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 the sleep mode in which the STA stops monitoring the wireless channel. In the sleep mode, the STA can save power because it stops supplying power to the packet detection component. The STA may notify the AP before entering the sleep mode so that the AP does not send packets to the STA while the STA is in the sleep mode. After the STA exits the sleep mode, the AP may resume sending packets to the STA. Operating in the sleep mode may cause a greater latency for packet delivery, and thus in many situations the STA may avoid the sleep mode. To avoid the sleep mode, the STA may spend a significant amount of time in the listen mode where it continuously powers the packet detection component.

[0017] Various aspects of the present disclosure generally relate to techniques for saving power when a STA is monitoring a wireless channel for packets. Some aspects more particularly relate to STAs that can implement 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 be powered on. When the STA is not monitoring the wireless channel in the listen mode, the STA may configure the packet detection component to be powered off. The STA's packet detection component may include one or more components of the RF front end, an analog-to-digital converter (ADC), and one or more components of the baseband processing unit. In some implementations, the STA may alternate between being powered on and powered off based on a duty cycle, as further described herein. 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 the receive mode. In the receive mode, the STA may remain powered on to receive and process the packet.

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

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

[0020] To realize one or more of the following potential advantages, certain implementations of the subject matter described in this disclosure may be carried out. Conventional techniques for monitoring a wireless channel in listen mode may involve continuously powering a packet detection component as they continuously monitor the wireless channel. In some implementations, a STA may intermittently monitor the wireless channel by seeking a packet preamble in listen mode. By intermittently monitoring the wireless channel, the STA may reduce the power consumed during listen mode. In the case of a STA without a cooling fan, reducing power consumption enables the STA to operate at a lower temperature. In the case of a STA operating 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 the STA when future wireless standards (such as future IEEE 802.11 standards) change the packet preamble. For example, based on future modifications to the packet preamble, some implementations of the STA may spend more time in a powered-off state when intermittently monitoring the wireless channel. Since a WLAN typically includes multiple STAs, the power savings can be significant.

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

[0022] Each of the STAs 104 may also be referred to as, among other possible examples, a Mobile Station (MS), a mobile device, a mobile handset, a wireless handset, an Access Terminal (AT), a User Equipment (UE), a Subscriber Station (SS), or a subscriber unit. The STA 104 may represent, among other possible examples, a mobile phone, a Personal Digital Assistant (PDA), other handheld devices, a netbook, a notebook computer, a tablet computer, a laptop, a display device (e.g., in particular, a TV, a computer monitor, a navigation system), a music or other audio or stereo device, a remote control device (“remote”), a printer, a kitchen appliance or other household appliance, a key fob (e.g., for a Passive Keyless Entry and Start (PKES) system), and various other devices.

[0023] A single AP102 and an associated set of STAs104 may be referred to as a basic service set (BSS) managed by the respective AP102. FIG. 1 additionally shows an exemplary coverage area 108 of an AP102 that may represent the basic service area (BSA) of the WLAN100. A BSS may be identified to a user by a service set identifier (SSID) and to other devices by a basic service set identifier (BSSID), which may be the media access control (MAC) address of the AP102. The AP102 periodically broadcasts a beacon containing the BSSID to enable any STA104 within the wireless range of the AP102 to establish or maintain a communication link 106 (hereinafter also referred to as a “Wi-Fi link”) with the AP102. For example, the beacon may include identification information of the primary channel used by the respective AP102, as well as a timing synchronization function for establishing or maintaining timing synchronization with the AP. The AP102 may provide access to an external network (such as network 140) to various STAs104 in the WLAN via the respective communication link 106. To establish a communication link 106 with the AP102, each of the STAs104 is configured to perform a passive scan operation or an active scan operation (“scan”) on a frequency channel within one or more frequency bands (e.g., 2.4 GHz, 5 GHz, 6 GHz, or 60 GHz bands). To perform a passive scan, the STA104 listens for beacons, which are transmitted by the respective AP102 at a periodic time interval called the target beacon transmission time (TBTT) (measured in time units (TU), where 1 TU may be equal to 1024 microseconds (μs)). To perform an active scan, the STA104 generates probe requests, transmits them continuously on each channel to be scanned, and listens for probe responses from the AP102.Each STA104 may be configured to perform authentication and association operations to identify or select an AP102 to be associated based on scan information obtained through passive or active scanning, and to establish a communication link 106 with the selected AP102. The AP102 may assign an association identifier (AID) to the STA104 in achieving the association operation, and the AP102 uses the association identifier (AID) to track the STA104.

[0024] As a result of the increasing pervasiveness of wireless networks, the STA104 may have an opportunity to select one of many BSSs within the range of the STA or to select from among a plurality of AP102s that together form an extended service set (ESS) including a plurality of connected BSSs. An extended network station associated with the WLAN100 may be connected to a wired or wireless distribution system that may enable a plurality of AP102s to be connected within such an ESS. Thus, the STA104 can be covered by two or more AP102s and can associate with different AP102s at different times for different transmissions. Additionally, after association with an AP102, the STA104 may also be configured to periodically scan its surroundings to find a more suitable AP102 to be associated with. For example, a STA104 that is moving relative to its associated AP102 may perform a "roaming" scan to find another AP102 with more desirable network characteristics such as a larger RSSI or a reduced traffic load.

[0025] In some cases, STA104 may form a network without involving AP102 or other devices other than STA104 itself. An 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, an ad-hoc network may be implemented within a larger wireless network such as WLAN100. In such an implementation, STA104 may be able to communicate with each other through AP102 using communication link 106, but STA104 may also be able to communicate directly with each other via direct wireless link 107. Additionally, two STA104 may communicate via direct communication link 107 regardless of whether both STA104 are associated with the same AP102 and served by the same AP102. In such an ad-hoc system, one or more of STA104 may assume the role fulfilled by AP102 in a BSS. Such STA104 may sometimes be called a group owner (GO) and may coordinate transmissions within the ad-hoc network. Examples of direct wireless link 107 include Wi-Fi Direct connections, connections established by using Wi-Fi Tunneled Direct Link Setup (TDLS) links, and other P2P group connections.

[0026] AP102 and STA104 may function and communicate (each via its respective communication link 106) in accordance with the IEEE 802.11 standard family (such as defined by the IEEE 802.11-2016 specification or its amendments, 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 the Medium Access Control (MAC) layer. AP102 and STA104 transmit and receive wireless communication (hereinafter also referred to as "Wi-Fi communication") with each other in the form of Physical Layer Convergence Protocol (PLCP) Protocol Data Units (PPDUs).

[0027] Each frequency band may include a plurality of sub-bands or frequency channels. For example, PPDUs compliant with the IEEE802.11n, 802.11ac, 802.11ax, and 802.11be standard amendments can be transmitted via the 2.4 GHz band and the 5 GHz band, each of which is divided into a plurality of 20 MHz channels. Therefore, these PPDUs are transmitted via a physical channel having a minimum bandwidth of 20 MHz, but larger channels can be formed through channel bonding. For example, PPDUs compliant with the IEEE802.11n, 802.11ac, 802.11ax, and 802.11be standard amendments can be transmitted via a physical channel having a bandwidth 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 that can be allocated continuously or non-continuously. For example, IEEE802.11n describes the use of a maximum of 2 channels (for a combined 40 MHz bandwidth) and defines a high throughput (HT) transmission format. IEEE802.11ac describes the use of a maximum of 8 channels (for a maximum combined 160 MHz bandwidth) and defines a very high throughput (VHT) transmission format. IEEE802.11ax also supports up to a combined 160 MHz bandwidth (which may be a combination of up to 8 channels each 20 MHz wide). IEEE802.11be 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 AP 102 and STA 104 in the WLAN 100 may transmit PPDUs via unlicensed spectrum, which may be a portion of the spectrum including frequency bands such as the 2.4 GHz band, 5 GHz band, 60 GHz band, and 900 MHz band, which have conventionally been used by Wi-Fi technology. Some implementations of the AP 102 and STA 104 described herein may also communicate within other frequency bands, such as the 6 GHz band, that may support both licensed and unlicensed communications. The AP 102 and STA 104 may also be configured to communicate via other frequency bands, such as shared licensed frequency bands, for which multiple operators may have licenses to operate within the same or overlapping one or more frequency bands.

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

[0030] Figure 2 shows a diagram 200 that illustrates an exemplary STA 201 alternating between modes and power states when monitoring for packets via 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 alternate between a receive mode and a listen mode. A mode graph 205 shows 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 via 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 the listen mode 208, the STA 201 may intermittently monitor the wireless channel 211 for packets. For example, the STA 201 may alternate between monitoring and not monitoring the wireless channel 211 for packets such as packets transmitted by the AP 202. When monitoring the wireless channel 211 in the listen mode 208, the STA 201 may configure the packet detection component to be powered on. When not monitoring the wireless channel 211 in the listen mode 208, as further described in FIGS. 4 - 6, the STA 201 may configure the packet detection component to be powered off. For example, in the listen mode 208, the STA 201 may alternate one or more components of the RF front end, the ADC, and the baseband processing unit between a powered off state and a powered on state.

[0031] The power state graph 213 shows an example of the STA 201 alternating between the powered-on state and the powered-off state. Alternating between the powered-on state and the powered-off state is sometimes also referred to as toggling between power states. The timeline 209 indicates the time progressing from left to right. As shown in FIG. 2, the AP 202 may transmit the first packet 203 via the wireless channel 211. The STA 201 may enter the receive mode 206 (at time = 0) to receive the first packet 203 and start processing it. In the receive mode 206, the packet detection component of the STA 201 may remain in the powered-on state to receive and process the first packet 203 (see segment 212 of the power state graph 213). After receiving the first packet 203, the STA 201 may switch to the listen mode 208.

[0032] STA201 may enter (at time = 7) a listen mode 208 in which STA201 may intermittently monitor a wireless channel 211 for packets. When monitoring the wireless channel 211 in the listen mode 208, STA201 may configure a packet detection component to be powered on (such as in segment 214 of the power state graph 213). For example, STA201 may provide power to the packet detection component to enter the powered on state. When not monitoring the wireless channel 211 in the listen mode 208, the STA may configure the packet detection component to be powered off (such as in segment 215 of the power state graph 213). For example, as further described in FIGS. 4-6, STA201 may stop providing power to the packet detection component to enter the powered off state. In some implementations, the duration of the powered on state may be approximately the same as the duration of the powered off state. The power state graph 213 shows that the powered off state persists over a single time unit and the powered on state persists over a single time unit. However, the powered on state and the powered off state may have any suitable duration. In some implementations, the duration of the powered on state may be different from the duration of the powered off state. For example, the powered off state may persist over a single time unit and the powered on state may persist over 1.5 time units. In some implementations, STA201 may alternate between the powered on state and the powered off state 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 off 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, STA201 may transition to the receive mode 206.

[0033] As shown in FIG. 2, the AP202 may transmit the second packet 204 via the wireless channel 211 (at time = 16). The STA201 may detect the second packet 204 and may change from the listen mode 208 to the receive mode 206. The transition from the listen mode 208 to the receive mode 206 is further described in FIGS. 5 and 6. While in the receive mode 206, the packet detection component may remain powered on to receive and process the second packet 204 (see segment 216 of the power state graph 205). The STA201 may remain in the receive mode 206 until the processing of the second packet 204 is complete. The STA201 may then transition to the listen mode (not shown), and the process may continue to repeat accordingly.

[0034] FIG. 3 shows a diagram 300 illustrating that an exemplary STA201 alternates between modes and power states when monitoring for beacon frames via a wireless channel 211. The STA201 may monitor the wireless channel 211 for beacon frames from the AP202. The STA201 may switch between a listen mode, a receive mode, and a sleep mode. A mode graph 305 shows an example of the STA201 switching between a listen mode 208, a receive mode 206, and a sleep mode 304. In the sleep mode 304, the STA201 may enter a power-off state where the STA201 stops powering the packet detection component therein. The STA201 may determine a duration for the sleep mode 304 based on a time interval during which the AP202 broadcasts beacon frames via 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 a first beacon frame 303). The AP202 may enter the sleep mode 304 between a beacon frame and a “wake-up” into a temporal listen mode 208 for detecting the next beacon frame. If a beacon frame is detected during the listen mode 208, the STA201 may enter a receive mode 206 where the STA201 processes the beacon frame therein.

[0035] The power state graph 313 shows an example of the STA201 alternating between the powered-on state and the powered-off state. The timeline 309 indicates the time progressing from left to right. As shown in the figure, the STA201 may enter the listen mode 208 in which the STA201 intermittently monitors the wireless channel while seeking a beacon frame therein. In the listen mode 208, the STA201 may alternate the packet detection component between the powered-on state and the powered-off state. During the powered-on state, the STA201 may supply power to the packet detection component and may monitor the wireless channel 211. During the powered-off state, as further described in FIGS. 4 to 6, the STA201 may stop supplying power to the packet detection component and may stop monitoring the wireless channel 211.

[0036] As shown in FIG. 3, the AP202 may transmit a first beacon frame 303 via the wireless channel 211. The STA201 may detect the first beacon frame 303 and may enter the receive mode 206. During the receive mode 206, the STA201 may remain in the powered-on state to process the first beacon frame 303.

[0037] As shown in FIG. 3, the STA201 may enter the sleep mode 304. During the sleep mode 304, the STA201 may configure its packet detection component to be in the powered-off state. The duration of the sleep mode 304 may depend on the time interval during which the AP202 broadcasts a beacon frame via the wireless channel 211. The STA201 may wake up from the sleep mode 304 and may enter the listen mode 208. As shown in FIG. 3, the AP202 may transmit a second beacon frame 312. The STA201 may detect the second beacon frame 312 and may enter the receive mode 206 during which the STA201 may process the second beacon frame 312.

[0038] FIG. 4 is a block diagram showing an exemplary STA201 including a power state controller 404 that can control the power state of the STA201. The STA201 may include a 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 related to a packet. The baseband processing unit 410 may process the digital information using various filters and digital processing components such as a baseband processor. For example, during the 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 the listen mode, the baseband processing unit may perform matched filter processing to detect a packet preamble in the digital information.

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

[0040] In some implementations, the power state controller 404 may continuously supply power to the synthesizer and PLL 418 of the RF front end 406. For example, even when the RFA 416, mixer 414, and filter 412 are in a powered-off state, the synthesizer and PLL 418 may remain in a powered-on state. The power state controller 404 may also continuously supply power to some filters and components of the baseband processing unit 410 even if the RFA 416 or other components are in a powered-off state during the listen mode. During the 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-off state. During the 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] Figure 5 shows an example in which the listen mode alternates between the powered-on state and the powered-off state when monitoring for a PPDU. In some implementations, STA201 may detect and process a legacy PPDU 502 in the listen mode. The legacy PPDU 502 may include a preamble that includes 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, STA201 may detect and process a mixed-mode PPDU 511 in the listen mode. The mixed-mode PPDU 511 may include one or more next-generation preambles, such as a legacy preamble, as well as one or more of an HT preamble, a VHT preamble, and an extremely high throughput (EHT) preamble. As shown in Figure 5, in one example, the 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 the wireless channel, the transmission of the L-STF (such as L-STF 504 or L-STF 512) and the transmission of other fields (such as L-LTF 506 or L-LTF 514) may have several durations defined by the IEEE 802.11 standard. For example, the transmissions of L-STF 504 and L-STF 512 may each have a duration of approximately 8 μs. In some implementations, L-STF 504 and L-STF 512 may each include STF information that is repeated 10 times over 8 μs, as further described in Figure 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, that is transmitted over 8 μs, as further described in Figure 6.

[0042] As shown in FIG. 5, STA201 may operate in a listen mode when a legacy PPDU 502 is transmitted via a wireless channel. The transmission of the legacy PPDU 502 may occur at any time during the listen mode. Thus, the reception of the L-STF 504 may occur while STA201 is monitoring the wireless channel (power-on state), or while the STA is not monitoring the wireless channel (power-off state). To avoid missing the L-STF 504, STA201 may alternate between monitoring (power-on state) and not monitoring (power-off state) using a duty cycle that enables detection of the L-STF 504 within the 8 μs transmission of the L-STF 504. For example, in some implementations, STA201 may be able to detect the L-STF 504 via autocorrelation within at least two power state cycles (further described in FIG. 6), where a power state cycle includes a power-on state and a power-off state having a duration based on the duty cycle. In some implementations, the number of power state cycles for detecting 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, STA201 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. STA201 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 for detecting 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, STA201 may detect the L-STF 504 within two power state cycles when the signal-to-noise ratio (SNR) is less than an SNR threshold, and within more power state cycles when the SNR exceeds the SNR threshold. Additional details regarding detecting the packet preamble are provided in the description of FIG. 6.

[0043] The power graph 531 indicates that the STA201 alternates the packet detection component between the powered-on state and the powered-off state to detect the L-STF504 or L-STF512. The STA201 may alternate between the powered-on state and the powered-off state based on the duty cycle. According to the power graph 531, the STA201 may be operating in the first powered-on state 537 of the listen mode 208. The timing line 534 indicates that the STA201 may receive at least a portion of the L-STF504 during the first powered-on state 537. During the first powered-on state 537, the STA201 monitors the wireless channel when the L-STF504 (or L-STF512) is received. The following example describes receiving the L-STF504 of the legacy PPDU502, but similar steps may be performed to receive the L-STF512 of the mixed mode PPDU511. In some implementations, as further described in FIG. 6, if the STA201 has sufficient time in the powered-on state to detect at least two repetitions of the STF information in the L-STF504, the STA201 may detect the L-STF504. As shown in FIG. 5, the STA201 may receive the L-STF504 without having sufficient time in the first powered-on state 537 to detect the L-STF504 (such as by detecting two repetitions of the STF information via autocorrelation). As illustrated, without detecting the L-STF504, the STA201 may switch to the powered-off state 538 according to the duty cycle, and thus, the STA201 may stop monitoring the wireless channel until the next powered-on state. During the second powered-on state 540, the STA201 may resume operations to monitor the wireless channel for preamble information (such as the L-STF504). In the second powered-on state 540, the STA201 may detect the L-STF504 (such as by detecting two repetitions of the STF information via autocorrelation). After detecting the L-STF504, the STA201 may switch to the receive mode 206 to process the legacy PPDU502 in the powered-on state.In some implementations, STA201 may detect L-STF504 by detecting any suitable number of repetitions of the STF information of L-STF504 in any suitable number of powered-on states. The number of repetitions of the STF for detecting L-STF504 and the number of powered-on states may depend on a specific packet detection technique (such as autocorrelation).

[0044] In some implementations, STA201 may determine whether to alternate between a powered-on state and a powered-off state during the listen mode according to the RSSI associated with a packet (such as legacy PPDU502 or mixed-mode PPDU511). For example, if the RSSI is greater than an RSSI threshold (such as -85 dBM), STA201 may alternate between a powered-on state and a powered-off state during the 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), STA201 may alternate between a powered-on state and a powered-off state during the listen mode. However, if the RSSI is less than the second RSSI threshold (-85 dBM), STA201 may remain in the powered-on state throughout the listen mode.

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

[0046] In listen mode, STA201 may switch between monitoring the wireless channel for PPDU600 and not monitoring the wireless channel. The operations for monitoring the wireless channel may include at least one wireless and data path calibration operation. The wireless and data path calibration operations may power on an RF front end (such as RF front end 406) after a power-off state. The wireless and data path calibration operations may also enable the wireless and data paths in the RF front end to be calibrated and ready to perform additional operations for monitoring the wireless channel. The monitoring operations may also include at least one autocorrelation operation for detecting the L-STF604 of PPDU600 (such as by detecting the repetition of the STF information included in L-STF604). The operations for not monitoring the wireless channel may include operations for configuring the packet detection component to a power-off state. In listen mode, STA201 may switch between monitoring the wireless channel and not monitoring the wireless channel until a packet preamble, such as the L-STF604 of packet preamble 602, is detected. When STA201 detects the L-STF604, STA201 may perform operations to prepare for processing the L-LTF606. 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 RFA416) to improve the strength or amplitude of the received signal related to PPDU600 for further processing. The coarse timing operation may follow the gain change operation. The coarse timing operation may adjust the coarse timing of RF front end 406 to align the frame to the symbol boundary of L-LTF606.

[0047] As shown in FIG. 6, an exemplary operation sequence 620 may include operations for the listen mode. The operation sequence 620 may start with operations for monitoring the wireless channel to seek a PPDU 600. For example, the operation sequence 620 may start with a first radio and data path conditioning operation 610 and a first autocorrelation operation 612. In some implementations, if the STA 201 starts an autocorrelation operation (such as the first autocorrelation operation 612) after receiving the L-STF 604, the STA 201 may be able to detect 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 by which the STA 201 stops monitoring the wireless channel thereby. For example, the operation sequence 620 may perform a power-off operation 618 to stop monitoring the wireless channel. After the power-off operation 618, the STA 201 may resume monitoring the wireless channel. For example, the STA 201 may perform a second radio and data path conditioning operation 611 and a second autocorrelation operation 613. During the operation sequence 620, the STA 201 may detect the L-STF 604 by performing the second autocorrelation operation 613 after receiving the L-STF 604. In some implementations, the second autocorrelation operation 613 may be able to detect two repetitions of the STF information in the L-STF 604. After detecting the L-STF 604, the STA 201 may perform operations to prepare for processing 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 for processing the L-LTF 606. After preparing for the L-LTF 606, the STA 201 may switch to the receive mode. In the receive mode, the STA 201 may perform operations for processing the L-LTF 606 and the remainder of the PPDU 600.

[0048] The operations in listen mode and receive mode may have associated power states. When monitoring the wireless channel in listen mode, the power state controller 404 of STA201 may configure the packet detection component to be powered on. When STA201 stops monitoring the wireless channel, the power state controller 404 may configure the packet detection component to be powered off. As shown in FIG. 6, an exemplary power graph 608 shows the power states associated with the operations performed in listen mode and receive mode. As shown in the operation sequence 620, the listen mode may include first radio and data path tuning operations 610. The power state controller 404 may provide power to the packet detection component to enter the powered-on state for the first radio and data path tuning operations 610, as shown in the power graph 608. The power state controller 404 may keep the packet detection component powered on for the first autocorrelation operation 612, as shown in the power graph 608. After monitoring the wireless channel, STA201 may stop monitoring the wireless channel. To stop monitoring the wireless channel, the power state controller 404 may perform a power-off operation 618. For the power-off operation 618, the power state controller 404 may stop providing power to the packet detection component to enter the powered-off state, as shown in the power graph 608. STA201 may resume monitoring the wireless channel by performing second radio and data path tuning operations 611. For the second radio and data path tuning operations 611, the power state controller 404 may provide power to the packet detection component to enter the powered-on state. The power state controller 404 may keep the packet detection component powered on for the second autocorrelation operation 613, gain change operation 614, and coarse timing operation 616, as shown in the power graph 608. As shown in the power graph 608, the packet detection component may remain powered on throughout the receive mode.

[0049] The operation in the listen mode may involve timing aspects related to the PPDU. For example, the PPDU may have one or more transmission times defined in the IEEE 802.11 standard. As shown in FIG. 6, the L-STF604 can be transmitted within 8 μs. In some implementations, the listen mode operation can detect the L-STF604 within 8 μs. The listen mode operation may include operations for monitoring the wireless channel, operations for not monitoring the wireless channel, and operations for preparing the L-LTF. As shown in FIG. 6, the operations for monitoring the wireless channel may include a first radio and data path calibration operation 610 and a first autocorrelation operation 612. In some implementations, the first radio and data path calibration 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 STA201 may stop monitoring the wireless channel by performing a power-off operation 618. In some implementations, the STA201 may stop monitoring the wireless channel for 2.4 μs as shown in the operation sequence 620. Thus, 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-STF604, the STA201 may perform operations to prepare for processing the L-LTF606. For example, the STA201 may perform a gain change operation 614 and a coarse timing operation 616 to prepare for processing the L-LTF606. In some implementations, as shown in the 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. Thus, the operations for preparing the L-LTF606 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 L-LTF606 (2.8 μs) may be 8 μs (2.8 μs + 2.4 μs + 2.8 μs = 8 μs). Since the total duration of the listen mode operation is 8 μs, STA201 can detect L-STF604 within that 8 μs transmission time.

[0050] Another timing aspect of the listen mode is related to detecting the L-STF when monitoring the wireless channel. In some implementations, STA201 may perform an autocorrelation operation to detect the L-STF, such as by detecting repetitions of the STF information related to 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 the L-STF can be received and still be detected within the autocorrelation operation. As shown in FIG. 6, STA201 may have a detection duration 625 for detecting a portion of L-STF604 (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 at which the L-STF604 can arrive and be detected by the first autocorrelation operation 612. In FIG. 6, the timing line 630 indicates that the L-STF604 arrives after the arrival deadline 624, and thus the L-STF604 is not detected. If the L-STF604 had arrived before the arrival deadline 624, STA201 may have detected the L-STF604. In some implementations, the detection duration 625 may affect how long STA201 stops monitoring the wireless channel. For example, if the detection duration 625 is longer, the duration of the power-off operation 618 may be shortened to ensure that STA201 can detect the L-STF604 within 8 μs.

[0051] Another timing aspect of the listen mode relates to coarse timing. In some implementations, the STA201 may perform a coarse timing operation when preparing to process the L-LTF. For example, as shown in FIG. 6, the STA201 may perform a coarse timing operation 616 when preparing to process the L-LTF606. The coarse timing deadline may indicate the latest time at which the STA201 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 STA201 may not be able to process the L-LTF. As shown in FIG. 6, the timing line 627 indicates when the STA201 receives the L-STF606. The coarse timing deadline 626 indicates the latest time at which the STA201 can complete the coarse timing operation 616 and still be able to process the L-LTF606. 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 STA201 may stop monitoring the wireless channel. For example, if the coarse timing deadline 626 is shorter, the duration of the power-off operation 618 may be shortened to ensure that the STA201 can detect the L-STF604 within 8 μs.

[0052] In some implementations, STA201 may reduce the time in the powered-on state in listen mode. For example, STA201 reduces the time for monitoring the wireless channel in the powered-on state. The operations for monitoring the wireless channel may include wireless and data path calibration operations (such as wireless and data path calibration operation 610) and autocorrelation operations (such as first autocorrelation operation 612). In some implementations, the autocorrelation operation may be replaced with a matched filter processing operation. For example, instead of using autocorrelation to detect the L-STF, STA201 may use matched filter processing to detect the L-STF. The matched filter processing operation may use pattern matching to detect the L-STF. For example, the matched filter processing operation may detect the L-STF by using pattern matching to detect a single repetition of the STF information. In some implementations, the matched filter processing operation may have a duration of 1 μs (compared to 1.6 μs for some implementations of the autocorrelation operation). In some implementations, STA201 may monitor the wireless channel by performing both wireless and data path calibration operations and the matched filter processing operation. The combined duration for the matched filter processing operation (1 μs) and the wireless and data path calibration operation (1.2 μs) may be 2.2 μs. Thus, the duration for monitoring the wireless channel may be 2.2 μs.

[0053] In some implementations, STA201 may also perform a coarse timing operation (such as coarse timing operation 616) using a 1-μs matched filter processing operation. When STA201 uses a 1-μs matched filter processing operation for a coarse timing operation (such as for operation 616), STA201 may stop monitoring the wireless channel for 3.6 μs. Thus, the duration of the operations 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 having 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 having a duration of 10 μs or more. In some implementations, STA201 may perform operations in a powered-on state for 2.2 μs, as described with respect to FIG. 6. Given a 10 μs L-STF and a 2.2 μs powered-on state operation, the STA can remain in a powered-off state for 3.6 μs and still detect the L-STF604 within 10 μs. Given a 10 μs L-STF and the timing of the powered-on state operations shown in FIG. 6, STA201 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 operations for detecting the L-STF.

[0055] FIG. 7 shows a process 700 for wireless communication in a WLAN, including exemplary operations performed by a device 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 a STA, such as one of STA104, 201, and 904 described with reference to FIGS. 1, 2, 3, and 9B.

[0056] In block 710, a device of a first WLAN device may alternate one or more components of the first WLAN device between a powered-off state and a powered-on state during a listen mode of the first WLAN device.

[0057] In block 720, the apparatus may receive preamble information of a packet from a second WLAN device during a powered-on state.

[0058] FIG. 8 shows a block diagram of an exemplary wireless communication device 800. In some implementations, wireless communication device 800 may be an example of a device for use in a STA such as one of STA104 or STA201 described herein. In some implementations, wireless communication device 800 may be an example of a device for use in an AP such as AP102 described herein. Wireless communication device 800 may generally be referred to as a device or a wireless communication device. Wireless communication device 800 is capable of transmitting (or outputting for transmission) and receiving wireless communication (e.g., in the form of wireless packets). For example, wireless communication device 800 may be configured to transmit and receive packets in the form of PPDUs and MPDUs compliant with the IEEE 802.11 standard as defined by the IEEE 802.11-2016 specification or its amendments, including, but not limited to, 802.11ah, 802.11ad, 802.11ay, 802.11ax, 802.11az, 802.11ba, and 802.11be, in addition to future 802.11 standards.

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

[0060] The modem 802 can include intelligent hardware blocks or devices, such as application-specific integrated circuits (ASICs), among other possible examples. The modem 802 is generally configured to implement the PHY layer. For example, the modem 802 is configured to modulate a packet for transmission over the wireless medium and output the modulated packet to the radio 804. The modem 802 is similarly configured to obtain the modulated packet received by the radio 804 and demodulate the packet to provide a demodulated packet. In addition to modulators and demodulators, the modem 802 may further include digital signal processing (DSP) circuitry, automatic gain control (AGC), coders, decoders, multiplexers, and demultiplexers. For example, during the transmit mode, data obtained from the processor 806 is provided to a coder, which encodes the data to provide encoded bits. The encoded bits are mapped to points in a modulation constellation (using the selected MCS) to provide modulated symbols. The modulated symbols are the number N SS of spatial streams or the number N STSIt can be mapped to a spatio-temporal stream. The modulated symbols in each spatial stream or spatio-temporal stream may be multiplexed, may be converted via an inverse fast Fourier transform (IFFT) block, and may then be provided to a DSP circuit configuration for Tx window processing 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 with beamforming, the modulated symbols in each spatial stream are precoded via a steering matrix before their provision to the IFFT block.

[0061] While in the receive mode, the digital signal received from the radio 804 is provided to a DSP circuit configuration, which is configured to acquire the received signal, for example, by detecting the presence of the signal and estimating the initial timing and frequency offset. The DSP circuit configuration is further configured to digitally condition the digital signal, for example, using channel (narrowband) filtering, analog impairment adjustment (such as correcting I / Q imbalance), and applying digital gain to ultimately obtain a narrowband signal. The output of the DSP circuit configuration may be supplied to an AGC, which is configured to use information extracted from the digital signal, for example, in one or more received training fields, to determine an appropriate gain. The output of the DSP circuit configuration is also coupled to a demodulator, which is configured to extract the modulated symbols from the signal and calculate, for example, the log-likelihood ratio (LLR) for each bit position of each subcarrier in each spatial stream. The demodulator is 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. The demultiplexed bits may be descrambled and provided to the MAC layer (processor 806) for processing, evaluation, or interpretation.

[0062] Wireless 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 in one or more transceivers. For example, the RF transmitter and the RF receiver may each include various DSP circuit configurations including at least one power amplifier (PA) and at least one low noise amplifier (LNA). The RF transmitter and the RF receiver may then 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 wireless 804, and the wireless 804 transmits those symbols via the coupled antennas. Similarly, symbols received via the antennas are acquired by the wireless 804, and the wireless 804 provides those symbols to the modem 802. In some implementations, the wireless 804 and one or more antennas may form one or more network interfaces (sometimes referred to as "interfaces").

[0063] Processor 806 can include intelligent hardware blocks or devices, such as, for example, a processing core, a processing block, a central processing unit (CPU), a microprocessor, a microcontroller, a digital signal processor (DSP), a programmable logic device (PLD) such as an application specific integrated circuit (ASIC), a field programmable gate array (FPGA), individual gates or transistor logic, individual hardware components, or any combination thereof designed to perform the functions described herein. Processor 806 processes information received through wireless 804 and modem 802 and processes information to be output through modem 802 and wireless 804 for transmission through the wireless medium. For example, processor 806 may implement a control plane and a MAC layer configured to perform various operations related to the generation and transmission of MPDUs, frames, or packets. The MAC layer is configured to perform or facilitate, among other operations or techniques, frame coding and decoding, spatial multiplexing, space-time block coding (STBC), beamforming, and OFDMA resource allocation. In some implementations, processor 806 may generally control modem 802 to cause the modem to perform the various operations described above.

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

[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 the power 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 these functionalities may be implemented, in part (or fully), in hardware or on the processor 806.

[0066] In some implementations, the processor 806 and the memory 808 of the wireless communication device 800 may be referred to as a processing system. A processing system generally refers to a system or series of machines or components that receive an input, process that input, and generate a set of outputs (which may be passed to another system or component, such as one of the STA104 or one of the AP102). In some implementations, the processing system may include one or more other components of the wireless communication device 800, such as the processor 806, the memory 808, and the modem 802.

[0067] In some implementations, the processing system of STA104 may interface with other components of STA104, may process information (such as input or signals) received from other components, and may output the information to other components and the like. For example, a chip or a modem of STA104 (such as 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 the receiver such that STA104 can receive an information or signal input and the information can 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 the transmitter such that STA104 can 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 an information or signal input and the first interface may also output, transmit, or provide information.

[0068] In some implementations, the processing system of AP102 may interface with other components of AP102, process information (such as inputs or signals) received from other components, and output the information to other components and the like. For example, a chip or a modem of AP102 (such as wireless communication device 800) may include a processing system, a first interface for receiving or obtaining 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 the modem and the receiver such that AP102 can receive information or signal inputs and the information can 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 the modem and the transmitter such that AP102 can transmit the information output from the chip or the modem. Those skilled in the art will readily recognize that the second interface may also obtain or receive information or signal inputs, and the first interface may also output, transmit, or provide information.

[0069] FIG. 9A shows a block diagram of an exemplary AP902. For example, AP902 may be an exemplary implementation of AP102 described herein. AP902 includes a wireless communication device 910. For example, wireless communication device 910 may be an exemplary implementation of wireless communication device 800 described with reference to FIG. 8. AP902 also includes a plurality of antennas 920 coupled to wireless communication device 910 for transmitting and receiving wireless communication. In some implementations, AP902 further includes, additionally, an application processor 930 coupled to wireless communication device 910, and a memory 940 coupled to application processor 930. AP902 further includes at least one external network interface 950 that enables AP902 to communicate with a core network or a backhaul network to obtain access to an external network including the Internet. For example, 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 components described above can communicate directly or indirectly with some of the other components via at least one bus. AP902 further includes a housing that encompasses at least a portion of wireless communication device 910, application processor 930, memory 940, as well as antennas 920 and external network interface 950.

[0070] FIG. 9B shows a block diagram of an exemplary STA904. For example, STA904 can be an exemplary implementation of STA104 or STA201 described herein. STA904 includes a wireless communication device 915. For example, wireless communication device 915 can be an exemplary implementation of wireless communication device 800 described with reference to FIG. 8. STA904 may also include one or more antennas 925 coupled to wireless communication device 915 for transmitting and receiving wireless communication. Additionally, STA904 may include an application processor 935 coupled to wireless communication device 915, and a memory 945 coupled to application processor 935. In some implementations, STA904 may further include a user interface (UI) 955 (such as a touch screen or keypad) and a display 965, and display 965 may be integrated with UI955 to form a touch screen display. In some implementations, STA904 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 components described above can communicate directly or indirectly with some of the other components via at least one bus. STA904 further includes a housing that encompasses at least portions of wireless communication device 915, application processor 935, memory 945, and antennas 925, UI955, and display 965.

[0071] FIG. 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 one of an AP (including any of the APs described herein), a range extender, a station (including any of the STAs described herein), or other electronic systems. The electronic device 1000 can include a processor 1002 (optionally including multiple processors, multiple cores, multiple nodes, or implementing multithreading, etc.). The electronic device 1000 can also include a memory 1006. The memory 1006 can be a system memory or any one or more possible realizations of the computer-readable media described herein. In some implementations, the processor 1002 and the memory 1006 may be referred to as a processing system. The electronic device 1000 can also include one or more network interfaces 1004 (sometimes referred to as "interfaces") including at least one of a bus 1010 (such as PCI, ISA, PCI-Express, HyperTransport®, InfiniBand®, NuBus®, AHB, AXI, etc.) and a wireless network interface (such as a WLAN interface, Bluetooth® interface, WiMAX® interface, ZigBee® interface, 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 various communication networks.

[0072] The electronic device 1000 may include a power state controller 404 that can perform operations for controlling 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 in the specification of the present 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 can include computer instructions executable by the processor 1002 to implement the functionality of the implementations described in FIGS. 1-10. Any of these functionalities can be implemented partially (or fully) in hardware or on the processor 1002. For example, the functionality may be implemented using application specific integrated circuits, within the logic implemented within the processor 1002, within a coprocessor on a peripheral device or card, etc. Further, the implementation may include fewer components or additional components not shown in FIG. 10 (such as a video card, an audio card, an additional network interface, a peripheral device, etc.). The processor 1002, the memory 1006, and the network interface 1004 are coupled to a bus 1010. Although shown as being coupled to the bus 1010, the memory 1006 may be coupled to the processor 1002.

[0074] The operations described in FIGS. 1-10 and herein are examples intended to assist in understanding the exemplary implementations and should not be used to limit the possible implementations or 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, and may perform some operations differently.

[0075] The above disclosure provides examples and explanations, but is not intended to be exhaustive or to limit the embodiments to the precise forms disclosed. Modifications and variations may be added in light of the above disclosure, or may be obtained from practice of the embodiments. Although embodiments of the present disclosure have been described with respect to various examples, any combination of embodiments from any of the examples is also within the scope of the present disclosure. The examples in this disclosure are provided for educational purposes. Alternatively, or in addition to the other examples described herein, the 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 implemented 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-off state and a powered-on state during a listen mode of the first WLAN device. The method may include receiving preamble information of a packet from a second WLAN device during the powered-on state.

[0077] Clause 2. The method of Clause 1, further comprising performing an 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 the powered-on state to perform an autocorrelation on the preamble information. The method further comprises ceasing to alternate one or more components of the WLAN device between a powered-off state and a powered-on state during the listen mode in response to detection of a preamble of the packet based on the autocorrelation. The method further comprises starting a receive mode for processing the packet.

[0079] Clause 4. One or more of the methods of Clauses 1 to 3, where the preamble of the packet includes a certain number of repetitions of preamble information. The method further includes detecting the preamble information by detecting one or more of the repetitions of the preamble information.

[0080] Clause 5. One or more of the methods of Clauses 1 to 4, where the certain number of repetitions of the preamble information includes a certain number of repetitions of STF information.

[0081] Clause 6. One or more of the methods of Clauses 1 to 5, where the duration of the power-off state and the duration of the power-on state are at least partially based on the number of repetitions of the preamble information and the duration of the time for detecting the preamble of the packet.

[0082] Clause 7. One or more of the methods of Clauses 1 to 6, where alternating one or more components between the power-off state and the power-on state includes alternating one or more components between the power-off state and the power-on state according to a duty cycle.

[0083] Clause 8. One or more of the methods of Clauses 1 to 7, where alternating one or more components of the first WLAN device between the power-off state and the power-on state is performed when the RSSI is greater than the RSSI threshold.

[0084] Clause 9. One or more of the methods of Clauses 1 to 8, where alternating one or more components of the first WLAN device between the power-off state and the power-on state is performed when the RSSI is greater than the first RSSI threshold and less than the second RSSI threshold.

[0085] Clause 10. One or more of the methods of Clauses 1 to 9, wherein one or more components of the first WLAN device include at least one of one or more components of the RF front end, the ADC, and one or more components of the baseband processing unit.

[0086] Clause 11. One or more of the methods of Clauses 1 to 10, further including performing a matched filter process on preamble information to detect the preamble of a packet.

[0087] Clause 12. One or more of the methods of Clauses 1 to 11, wherein the first WLAN device remains powered on to perform a matched filter process on the preamble of a packet.

[0088] Clause 13. Another inventive aspect of the subject matter described in this disclosure may be implemented 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-off 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 preamble information of a packet 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 an autocorrelation on the preamble information to detect the preamble of a packet.

[0090] Clause 15. One or more of the devices of one or more of Clauses 13 - 14, wherein the processor is further configured to stop alternating one or more components of the first WLAN device between a powered-off state and a powered-on state during the listen mode in response to detecting a preamble of a packet based on autocorrelation. The processor may be further configured to start a receive mode to process the packet.

[0091] Clause 16. One or more of the devices of one or more of Clauses 13 - 15, wherein the preamble of the packet includes a certain number of repetitions of preamble information, and wherein the detection of the preamble includes detection of one or more of the repetitions of the preamble information.

[0092] Clause 17. One or more of the devices of one or more of Clauses 13 - 16, wherein the certain number of repetitions of the preamble information includes a certain number of repetitions of STF information.

[0093] Clause 18. One or more of the devices of one or more of Clauses 13 - 17, wherein the duration of the powered-off state and the duration of the powered-on state are at least partially based on the number of repetitions of the preamble information and the duration of time for detecting the preamble of the packet.

[0094] Clause 19. One or more of the devices of one or more of Clauses 13 - 18, wherein the alternating of one or more components between the powered-off state and the powered-on state includes alternating one or more components between the powered-off state and the powered-on state according to a duty cycle.

[0095] Clause 20. One or more of the devices of one or more of Clauses 13 - 19, wherein the interface is further configured to obtain an RSSI related to the packet, and the alternating of one or more components of the first WLAN device between the powered-off state and the powered-on state is performed in response to the RSSI being greater than an RSSI threshold.

[0096] Clause 21. One or more devices among Clauses 13 to 20, wherein the interface is further configured to obtain the RSSI associated with the packet, and wherein the alternation of one or more components of the first WLAN device between the powered-off state and the 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. One or more devices among Clauses 13 to 21, wherein one or more components of the first WLAN device include at least one of one or more components of the RF front end, the ADC, and one or more components of the baseband processing unit.

[0098] Clause 23. One or more devices among Clauses 13 to 22, wherein the processor is further configured to perform a matched filter process on one or more fields of preamble information to detect the preamble of the packet.

[0099] Clause 24. Another inventive aspect of the subject matter described in this disclosure can be implemented in a non-transitory computer-readable medium that stores 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-off state and a powered-on state during a listen mode of the first WLAN device. The operations may cause the first WLAN device to obtain preamble information of a packet from a second WLAN device during a powered-on state.

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

[0101] Clause 26. One or more non-transitory computer-readable media of any one or more of Clauses 1-12 and 24-25, wherein the first WLAN device remains powered on to perform an autocorrelation on preamble information. The instructions further cause the first WLAN device to stop alternating one or more components of the WLAN device between a powered-off state and a powered-on state during a listen mode in response to detecting a preamble of a packet based on the autocorrelation, and to start a receive mode to process the packet.

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

[0103] Clause 28. Another inventive aspect of the subject matter described in this disclosure may be implemented 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-off 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 preamble information of a packet from a second WLAN device during a powered-on state.

[0104] Clause 29. An apparatus of any one or more of Clauses 1-12 and 28, further including means for performing an autocorrelation on preamble information to detect a preamble of a packet.

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

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

[0107] As used herein, the phrase referring to an enumeration of items "at least one of" refers to any combination of those items, including a single member. By way of example, "at least one of a, b, or c" shall include a, b, c, a-b, a-c, b-c, and a-b-c.

[0108] The various exemplary logics, logic blocks, modules, circuits, and algorithmic processes described with respect to the implementations disclosed herein may be implemented as electronic hardware, computer software, or a combination of both. The compatibility between hardware and software has generally been described from a functional perspective and is shown in the various exemplary components, blocks, modules, circuits, and processes described throughout. Whether such functionality is implemented in hardware or software is determined by the specific application example and the design constraints imposed on the overall system.

[0109] The hardware and data processing apparatus used to implement the various exemplary logics, logic blocks, modules, and circuits described in connection with the aspects disclosed herein may be implemented or performed using a general-purpose single-chip or general-purpose multi-chip processor, a digital signal processor (DSP), an application specific integrated circuit (ASIC), a field programmable gate array (FPGA) or other programmable logic device, discrete gates 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. The processor may also be implemented as a combination of computing devices, such as, a combination of a DSP and a microprocessor, a plurality of microprocessors, one or more microprocessors in conjunction with a DSP core, or any other such configuration. In some implementations, certain processes and methods may be performed by circuitry that is 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., 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] When implemented in software, the functions can be stored on a computer-readable medium or transmitted via a computer-readable medium as one or more instructions or codes. The processes of the methods or algorithms disclosed herein can be implemented in processor-executable software modules that may exist on a computer-readable medium. A computer-readable medium includes both a computer storage medium and a communication medium including any medium that can enable the transfer of a computer program from one place to another. The 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 can 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 the desired program code in the form of instructions or data structures and that can be accessed by a computer. Also, any connection may properly be termed a computer-readable medium. As used herein, disk and disc include compact disc (CD), laser disc, optical disc, digital versatile disc (DVD), floppy disk, and Blu-Ray (trademark) disc, where disk typically magnetically reproduces data and disc optically reproduces data using a laser. Combinations may also be included within the scope of computer-readable media. Additionally, the operations of a method or algorithm may exist on a machine-readable medium and a computer-readable medium that can be incorporated in a computer program product as one or more of the codes and instructions or any combination or set thereof.

[0112] Various modifications to the implementations described in this disclosure may become 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. Accordingly, the claims are not intended to be limited to the implementations shown herein but are to be accorded the widest scope consistent with the disclosure, the principles disclosed herein, and the novel features presented.

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

[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 separately in multiple implementations or in any suitable sub - combination. Moreover, features may be described as acting in some combinations and may even initially be claimed as such, but one or more features from the claimed combination may, in some cases, be deleted from that combination, and the claimed combination may be directed to a sub - combination or a variant of a sub - combination.

[0115] Similarly, while operations are shown in the drawings in a particular order, this should not be understood as requiring that such operations be performed in the particular order shown or in a sequential order, or that all of the illustrated operations be performed, to achieve desirable results. Further, the drawings may schematically show one or more exemplary processes in the form of a flowchart. However, other operations not shown may be incorporated into the exemplary processes that are schematically illustrated. For example, one or more additional operations may be performed before, after, simultaneously with, or between any of the illustrated operations. In some circumstances, multitasking and parallel processing may be advantageous. Moreover, the separation of various system components in the implementation forms described should not be understood as requiring such separation in all implementation forms, and it should be understood that the program components and systems described may generally be integrated together in a single software product or packaged into multiple software products. Additionally, other implementations fall 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 Signs

[0116] 100 Wireless communication network, WLAN 102 Access point (AP) 104 Station (STA) 106 Communication link 107 Direct wireless link, direct communication link 108 Coverage area 140 Other network 201 STA 202 AP 203 First packet 204 Second packet 205 Mode graph, power state graph 206 Receive mode 208 Listen mode 209 Timeline 211 Wireless Channel 213 Power State Graph 303 First Beacon Frame 304 Sleep Mode 305 Mode Graph 309 Timeline 312 Second Beacon Frame 313 Power State Graph 404 Power State Controller 406 RF Front End 408 Analog-to-Digital Converter (ADC) 410 Baseband Processing Unit 412 Filter 414 Mixer 416 RF Amplifier (RFA) 418 Synthesizer and Phase-Locked Loop (PLL) 502 Legacy PPDU 504 L-STF 506 L-LTF 508 Legacy Signal (L-SIG) Field 510 Data Field 511 Mixed Mode PPDU 512 L-STF 514 L-LTF 516 L-SIG 518 HT-SIG 520 HT-STF 522 HT-LTF 526 Data Field 531 Power Graph 534 Timing Line 537 First Power-On State 538 Power-Off State 540 Second Power-On 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 Tuning Operation 611 Second Radio and Data Path Tuning 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 Coarse Timing Deadline 627 Timing Line 630 Timing Line 800 Wireless Communication Device 802 Modem 804 Wireless 806 Processor 808 Memory 902 AP 904 STA 910 Wireless Communication Device 915 Wireless Communication Device 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 Device 1002 Processor 1004 Network Interface 1006 Memory 1010 Bus

Claims

1. A method for wireless communication in a Wireless Local Area Network (WLAN) performed by a first WLAN device, comprising: alternating one or more components of the first WLAN device between a powered-off state and a powered-on state during a listen mode of the first WLAN device; receiving preamble information of a packet from a second WLAN device during the powered-on state; A method comprising the above.

2. Further comprising performing an autocorrelation on the preamble information to detect the preamble of the packet. The method according to claim 1.

3. The first WLAN device remains in the powered-on state 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, stopping alternating the one or more components of the WLAN device between the powered-off state and the powered-on state during the listen mode; starting a receive mode for processing the packet. The method according to claim 2.

4. The preamble of the packet includes a certain number of repetitions of the preamble information, and the method further comprises: detecting the preamble information by detecting one or more of the repetitions of the preamble information. The method according to claim 1.

5. The method according to claim 4, wherein the certain number of repetitions of the preamble information includes a certain number of repetitions of Short Training Field (STF) information.

6. The method according to claim 4, wherein the duration of the powered-off state and the duration of the powered-on state are at least partially based on the certain number of repetitions of the preamble information and the duration of time for detecting the preamble of the packet.

7. The method according to claim 1, wherein alternating the one or more components between the powered-off state and the powered-on state includes alternating the one or more components between the powered-off state and the powered-on state according to a duty cycle.

8. The step of alternating the one or more components of the first WLAN device between the power-off state and the power-on state is performed when a received signal strength indicator (RSSI) is greater than an RSSI threshold, the method according to claim 1.

9. The step of alternating the one or more components of the first WLAN device between the power-off state and the power-on state is performed when the RSSI is greater than a first RSSI threshold and less than a second RSSI threshold, the method according to claim 1.

10. The one or more components of the first WLAN device are one or more components of a radio frequency (RF) front end, an analog-to-digital converter (ADC), and include at least one of one or more components of a baseband processing unit, the method according to claim 1.

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

12. The first WLAN device remains in the power-on state to perform the matched filter process on the preamble of the packet, the method according to claim 11.

13. An apparatus for a first WLAN device for wireless communication, configured to alternate one or more components of the first WLAN device between a power-off state and a power-on state during a listen mode of the first WLAN device, a processor; an interface configured to obtain preamble information of a packet from a second WLAN device during the power-on state An apparatus comprising.

14. The processor is further configured to perform an autocorrelation on the preamble information to detect the preamble of the packet, The apparatus according to claim 13.

15. The processor is based on the autocorrelation, in response to the detection of the preamble of the packet, stop alternating the one or more components of the first WLAN device between the power-off state and the power-on state during the listen mode, further configured to start a receive mode to process the packet, The apparatus according to claim 14.

16. The apparatus according to claim 13, wherein the preamble of the packet includes a certain number of repetitions of the preamble information, and the detection of the preamble includes the detection of one or more of the repetitions of the preamble information.

17. The apparatus according to claim 16, wherein the certain number of repetitions of the preamble information includes a certain number of repetitions of short training field (STF) information.

18. The apparatus according to claim 16, wherein the duration of the power-off state and the duration of the power-on state are at least partially based on the certain number of repetitions of the preamble information and the duration of the time for the detection of the preamble of the packet.

19. The apparatus according to claim 13, wherein the alternation of the one or more components between the power-off state and the power-on state includes the alternation of the one or more components between the power-off state and the power-on state according to a duty cycle.

20. The interface is further configured to obtain a received signal strength indicator (RSSI) related to the packet, and the alternation of the one or more components of the first WLAN device between the power-off state and the power-on state is performed in response to the RSSI being greater than an RSSI threshold. The apparatus according to claim 13.

21. The interface is further configured to obtain a received signal strength indicator (RSSI) related to the packet, and the alternation of the one or more components of the first WLAN device between the power-off state and the power-on state is performed in response to the RSSI being greater than a first RSSI threshold and less than a second RSSI threshold. The apparatus according to claim 13.

22. The one or more components of the first WLAN device are one or more components of a radio frequency (RF) front end, an analog-to-digital converter (ADC), and at least one of one or more components of a baseband processing unit. The apparatus according to claim 13.

23. The processor is further configured to perform a matched filter process on one or more fields of the preamble information to detect the preamble of the packet. The apparatus according to claim 13.

24. A non-transitory computer-readable medium storing instructions that, when executed by a processor of a first wireless local area network (WLAN) device, cause the first WLAN device to alternate one or more components of the first WLAN device between a powered-off state and a powered-on state during a listen mode of the first WLAN device; and obtain preamble information of a packet from a second WLAN device during the powered-on state. A non-transitory computer-readable medium. **Claim 25** The instructions further cause the first WLAN device to perform an autocorrelation on the preamble information to detect the preamble of the packet. The non-transitory computer-readable medium according to claim 24. **Claim 26** The first WLAN device remains in the powered-on state to perform the autocorrelation on the preamble information, and the instructions further cause the first WLAN device to in response to detection of the preamble of the packet based on the autocorrelation, stop alternating the one or more components of the WLAN device between the powered-off state and the powered-on state during the listen mode; and start a receive mode to process the packet. The non-transitory computer-readable medium according to claim 25. **Claim 27** The preamble information includes a repetition of a certain number of symbols, and the instructions further cause the first WLAN device to detect the preamble information by detecting one or more of the repetitions of the symbols. The non-transitory computer-readable medium according to claim 24. **Claim 28** An apparatus for a first WLAN device for wireless communication, comprising means for alternating one or more components of the first WLAN device between a powered-off state and a powered-on state during a listen mode of the first WLAN device; and means for obtaining preamble information of a packet from a second WLAN device during the powered-on state. An apparatus comprising the above. **Claim 29** Means for performing an autocorrelation on the preamble information to detect the preamble of the packet. The apparatus according to claim 28, further comprising the above. **Claim 30** The first WLAN device remains powered on to perform the autocorrelation on the preamble information, and the apparatus in response to detecting the preamble of the packet based on the autocorrelation, ceases alternating one or more components of the WLAN device between the powered-off state and the powered-on state during the listen mode, and further comprises means for starting a receive mode for processing the packet. The apparatus according to claim 29.

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