WO2017220037A1

WO2017220037A1 - Adaptive inactivity timeout management

Info

Publication number: WO2017220037A1
Application number: PCT/CN2017/090078
Authority: WO
Inventors: Sandip Homchaudhuri; Pradeep Kumar Yenganti; Yongchun XIAO; Alireza Raissinia; Jian Tao
Original assignee: Qualcomm Incorporated
Priority date: 2016-06-24
Filing date: 2017-06-26
Publication date: 2017-12-28
Also published as: TW201804839A; BR112018076356A2; WO2017220036A1; EP3476161A1; CN109314927A; KR20190019957A; AU2017282925A1; TW201804833A; WO2017219352A1; BR112018076350A2; EP3476159A1; KR20190019958A; EP3476160A1; JP2019522931A; CN109417757A; AU2017282924A1; KR20190019959A; EP3476159A4; EP3476160A4; EP3476161A4

Abstract

Methods, systems, and devices for wireless communication are described. One method may include communicating with an access point (AP) during awake intervals in which the wireless device is in an awake mode, determining a congestion level associated with a radio frequency (RF) spectrum band, and determining, for an awake interval, an inactivity timeout (ITO) interval for the wireless device to remain in the awake mode based on an identified RF spectrum band and the determined congestion level used by the wireless device to communicate with the AP. A second method may include polling an AP during a delivery traffic indication message (DTIM) period, and modifying timing for the station to poll the AP based on identifying that a trigger condition has been satisfied based on a determination that at least one null data message has been received from the AP, or a predetermined threshold number of polls have timed out.

Description

ADAPTIVE INACTIVITY TIMEOUT MANAGEMENT

BACKGROUND

The following relates generally to wireless communication at a station， and more specifically to adaptive inactivity timeout management.

Wireless communications systems are widely deployed to provide various types of communication content such as voice， video， packet data， messaging， broadcast， and so on. These systems may be multiple-access systems capable of supporting communication with multiple users by sharing the available system resources (e.g.， time， frequency， and power) . A wireless network， for example a wireless local area network (WLAN) ， such as a Wi-Fi (i.e.， Institute of Electrical and Electronics Engineers (IEEE) 802.11) network may include an access point (AP) that may communicate with one or more stations (STAs) or mobile devices. The AP may be coupled to a network， such as the Internet， and may enable a mobile device to communicate via the network (or communicate with other devices coupled to the access point) . A wireless device may communicate with a network device bi-directionally. For example， in a WLAN， a STA may communicate with an associated AP via downlink and uplink. The downlink (or forward link) may refer to the communication link from the AP to the station， and the uplink (or reverse link) may refer to the communication link from the station to the AP.

While power consumption of APs in the WLAN may also be of concern， STA power consumption may be of particular importance because such devices typically rely on power from one or more batteries. WLAN systems， such as those employing the 802.11 family of standards (e.g.， Wi-Fi) ， may use channel sense multiple access (CSMA) ， in which STAs sense channel conditions prior to accessing the channel. In WLAN systems， an AP may be communicating with several or many other STAs concurrently， and therefore data transfers may be interrupted by periods where the AP is serving other STAs. A STA may activate a power saving mode where the STA periodically or semi-periodically goes into a sleep mode and wakes up when data is to be exchanged between the AP and the STA. In some instances， after the last data packet is transmitted or received by a STA， the STA may remain in an awake mode in case there are any data packets in transit that have not yet been received. The STA may remain in the awake mode until expiration of an inactivity timeout (ITO) interval. However， even if there are no additional data packets to be received， the STA may wait and stay awake until the ITO interval has expired. This may result in an unnecessary drain in power without the added benefit of better performance.

SUMMARY

The described techniques relate to improved methods， systems， devices， or apparatuses that support adaptive inactivity timeout management. Generally， the described techniques provide for determining an inactivity timeout (ITO) interval for a station (STA) based on network congestion. The ITO may also be determined based on the radio frequency (RF) spectrum band used by the STA or the bandwidth mode of operation used by the STA， which may be associated with the RF spectrum band. In some examples， the congestion level may be determined based on different activity levels within the wireless network. For example， the ITO may depend on both the RF spectrum band used by the STA and the congestion in the RF spectrum band. The congestion level may also be determined based on the activity level of other devices operating in the RF spectrum band， and also based on reception activity associated with traffic sent to the STA in the RF spectrum band.

Additional adaptive inactivity timeout management techniques are also described that involve modifying timing for the STA to poll an access point (AP) based on whether the STA receives a certain number of null data messages or if the STA experiences a certain number of poll timeouts during a delivery traffic indication message (DTIM) period. In such cases， the STA may stop polling the AP to save power for the rest of the DTIM period， disable the modification of the timing for polling the AP， or disable polling (e.g.， power save polling) for the station. Other examples may include varying the interval between polls transmitted from the STA to the AP so that the polls end up spanning a DTIM period and/or varying the number of polls within the DTIM period.

A method of wireless communication at a station is described. The method may include communicating with an AP in a wireless communications network during awake intervals in which the wireless device is in an awake mode， identifying a RF spectrum band used by the wireless device to communicate with the AP， determining a congestion level associated with the RF spectrum band， and determining， for an awake interval of the awake intervals， an ITO interval for the wireless device to remain in the awake mode based at least in part on the identified RF spectrum band and the determined congestion level.

An apparatus for wireless communication at a station is described. The apparatus may include means for communicating with an AP in a wireless communications network during awake intervals in which the wireless device is in an awake mode， means for identifying a RF spectrum band used by the wireless device to communicate with the AP， means for determining a congestion level associated with the RF spectrum band， and means for determining， for an awake interval of the awake intervals， an ITO interval for the wireless device to remain in the awake mode based at least in part on the identified RF spectrum band and the determined congestion level.

Another apparatus for wireless communication at a station is described. The apparatus may include a processor， memory in electronic communication with the processor， and instructions stored in the memory. The instructions may be operable to cause the processor to communicate with an AP in a wireless communications network during awake intervals in which the wireless device is in an awake mode， identify a RF spectrum band used by the wireless device to communicate with the AP， determine a congestion level associated with the RF spectrum band， and determine， for an awake interval of the awake intervals， an ITO interval for the wireless device to remain in the awake mode based at least in part on the identified RF spectrum band and the determined congestion level.

A non-transitory computer readable medium for wireless communication at a station is described. The non-transitory computer-readable medium may include instructions operable to cause a processor to communicate with an AP in a wireless communications network during awake intervals in which the wireless device is in an awake mode， identify a RF spectrum band used by the wireless device to communicate with the AP， determine a congestion level associated with the RF spectrum band， and determine， for an awake interval of the awake intervals， an ITO interval for the wireless device to remain in the awake mode based at least in part on the identified RF spectrum band and the determined congestion level.

In some examples of the method， apparatus， and non-transitory computer-readable medium described above， identifying the RF spectrum band used by the wireless device comprises identifying a bandwidth mode of operation used by the wireless device to communicate with the AP. In some examples of the method， apparatus， and non-transitory computer-readable medium described above， the bandwidth mode of operation comprises a 20 megahertz (MHz) bandwidth mode， or a 40 MHz bandwidth mode， or an 80 MHz bandwidth mode， or a 160 MHz bandwidth mode， or an 80+80 MHz bandwidth mode， or a combination thereof.

In some examples of the method， apparatus， and non-transitory computer-readable medium described above， identifying the RF spectrum band used by the wireless device comprises identifying an RF spectrum range associated with the wireless communications network that may be used by the wireless device to communicate with the AP. In some examples of the method， apparatus， and non-transitory computer-readable medium described above， the RF spectrum range used by the wireless communications network may be associated with at least a 2.4 gigahertz (GHz) spectrum， or a 5 GHz spectrum， or a 900 MHz spectrum， or a 60 GHz spectrum， or a combination thereof.

In some examples of the method， apparatus， and non-transitory computer-readable medium described above， determining the congestion level associated with the RF spectrum band comprises determining the congestion level associated with the RF spectrum band during a first awake interval. In some examples of the method， apparatus， and non-transitory computer-readable medium described above， determining the ITO interval comprises determining the ITO interval for the wireless device to remain in the awake mode during the first awake interval， or a subsequent awake interval， or a combination thereof.

In some examples of the method， apparatus， and non-transitory computer-readable medium described above， determining the ITO interval comprises receiving multiple sounding triggers， determining intervals between sounding triggers of the received multiple sounding sequences， and determining the ITO based at least in part on the determined intervals.

In some examples of the method， apparatus， and non-transitory computer-readable medium described above， determining the ITO interval comprises determining that the congestion level associated with the RF spectrum band may be greater than a predetermined threshold for the identified RF spectrum band. Some examples of the method， apparatus， and non-transitory computer-readable medium described above may further include processes， features， means， or instructions for increasing the ITO interval for the wireless device to remain in the awake mode.

In some examples of the method， apparatus， and non-transitory computer-readable medium described above， the station and the AP operate according to at least a multi-user multiple input multiple output (MU-MIMO) mode， or a single-user multi-client (SU-MC) mode， or a combination thereof.

In some examples of the method， apparatus， and non-transitory computer-readable medium described above， the congestion level may be determined based at least in part on data received by the station in the RF spectrum band. In some examples of the method， apparatus， and non-transitory computer-readable medium described above， the congestion level may be further determined based at least in part on other activity in the wireless communications network in the RF spectrum band.

In some examples of the method， apparatus， and non-transitory computer-readable medium described above， the congestion level may be determined by identifying a first activity level in a RF spectrum band used by the first wireless device based at least in part on traffic transmitted to and received by the first wireless device， identifying， at the first wireless device， a second activity level in the RF spectrum band based at least in part on transmission and reception activity for at least one second wireless device， and estimating a congestion level for the RF spectrum based at least in part on the first activity level and the second activity level.

In some examples of the method， apparatus， and non-transitory computer-readable medium described above， estimating the congestion level comprises scaling the first and second activity levels by applying a scaling coefficient associated with the awake interval， and estimating the congestion level for the RF spectrum band based at least in part on the scaled first and second activity levels.

In some examples of the method， apparatus， and non-transitory computer-readable medium described above， the traffic transmitted to and received by the first wireless device comprises unicast data transmitted to the first wireless device. In some examples of the method， apparatus， and non-transitory computer-readable medium described above， the transmission and reception activity for the at least on second wireless device comprises a measurement of all wireless communications network activities in the RF spectrum band other than transmission and reception traffic associated with the first wireless device.

Another method of wireless communication at a station is described. The method may include determining a DTIM period， polling an AP during the DTIM period and while the station is in a sleep mode， identifying that a trigger condition has been satisfied， wherein the trigger condition is based at least in part on a determination that at least one null data message has been received from the AP， or a predetermined threshold number of polls have timed out， or a combination thereof， and modifying a timing for the station to poll the AP based at least in part on identifying that the trigger condition has been satisfied.

Another apparatus for wireless communication at a station is described. The apparatus may include means for determining a DTIM period， means for polling an AP during the DTIM period and while the station is in a sleep mode， means for identifying that a trigger condition has been satisfied， wherein the trigger condition is based at least in part on a determination that at least one null data message has been received from the AP， or a predetermined threshold number of polls have timed out， or a combination thereof， and means for modifying a timing for the station to poll the AP based at least in part on identifying that the trigger condition has been satisfied.

Another apparatus for wireless communication at a station is described. The apparatus may include a processor， memory in electronic communication with the processor， and instructions stored in the memory. The instructions may be operable to cause the processor to determine a DTIM period， poll an AP during the DTIM period and while the station is in a sleep mode， identify that a trigger condition has been satisfied， wherein the trigger condition is based at least in part on a determination that at least one null data message has been received from the AP， or a predetermined threshold number of polls have timed out， or a combination thereof， and modify a timing for the station to poll the AP based at least in part on identifying that the trigger condition has been satisfied.

Another non-transitory computer readable medium for wireless communication at a station is described. The non-transitory computer-readable medium may include instructions operable to cause a processor to determine a DTIM period， poll an AP during the DTIM period and while the station is in a sleep mode， identify that a trigger condition has been satisfied， wherein the trigger condition is based at least in part on a determination that at least one null data message has been received from the AP， or a predetermined threshold number of polls have timed out， or a combination thereof， and modify a timing for the station to poll the AP based at least in part on identifying that the trigger condition has been satisfied.

Some examples of the method， apparatus， and non-transitory computer-readable medium described above may further include processes， features， means， or instructions for adding the AP to a list of APs for which the station may have modified timing. Some examples of the method， apparatus， and non-transitory computer-readable medium described above may further include processes， features， means， or instructions for removing the AP from the list upon expiration of an aging factor associated with the AP.

Some examples of the method， apparatus， and non-transitory computer-readable medium described above may further include processes， features， means， or instructions for reassociating with the AP after modifying the timing for the station to poll the AP. Some examples of the method， apparatus， and non-transitory computer-readable medium described above may further include processes， features， means， or instructions for reverting to polling the AP during a second DTIM period according to a default timing. Some examples of the method， apparatus， and non-transitory computer-readable medium described above may further include processes， features， means， or instructions for modifying the default timing for the station to poll the AP based at least in part on a second identification that the trigger condition may have been satisfied during the second DTIM period.

In some examples of the method， apparatus， and non-transitory computer-readable medium described above， modifying the timing comprises identifying a remaining portion of the DTIM period， and stopping polling the AP for the remaining portion of the DTIM period. Some examples of the method， apparatus， and non-transitory computer-readable medium described above may further include processes， features， means， or instructions for resuming polling the AP during an immediately subsequent DTIM period.

In some examples of the method， apparatus， and non-transitory computer-readable medium described above， modifying the timing comprises adjusting a time interval between polls that the station transmits to the AP. In some examples of the method， apparatus， and non-transitory computer-readable medium described above， modifying the timing comprises identifying a consecutive number of polls sent from the station to the AP that may have timed out， and disabling polling for the station based at least in part on a determination that the consecutive number of polls may be greater than a predetermined threshold.

Some examples of the method， apparatus， and non-transitory computer-readable medium described above may further include processes， features， means， or instructions for identifying， for a plurality of polls sent from the station to the AP， a percentage of the plurality of polls that may have timed out. Some examples of the method， apparatus， and non-transitory computer-readable medium described above may further include processes， features， means， or instructions for disabling modifying the timing for the station to poll the AP based at least in part on a determination that the percentage may be greater than a predetermined threshold.

Some examples of the method， apparatus， and non-transitory computer-readable medium described above may further include processes， features， means， or instructions for deleting a first block acknowledgement (ACK) session based at least in part on a determination that the percentage may be greater than a predetermined threshold. Some examples of the method， apparatus， and non-transitory computer-readable medium described above may further include processes， features， means， or instructions for activating a second block ACK session with the AP after deleting the first block ACK session.

In some examples of the method， apparatus， and non-transitory computer-readable medium described above， polling the AP comprises transmitting multiple power saving polls (PS-Polls) to the AP at a plurality of intervals based at least in part on the number of null messages received from the AP or the threshold number of polls having timed out. In some examples of the method， apparatus， and non-transitory computer-readable medium described above， polling the AP comprises transmitting multiple speculative power saving polls (PS-Polls) to the AP at a plurality of intervals based at least in part on the determined DTIM period.

Another method of wireless communication at a station is described. The method may include identifying a first activity level in a RF spectrum band used by the first wireless device based at least in part on traffic transmitted to and received by the first wireless device， identifying， at the first wireless device， a second activity level in the RF spectrum band based at least in part on transmission and reception activity for at least one second wireless device， estimating a congestion level for the RF spectrum based at least in part on the first activity level and the second activity level， and determining， for an awake interval in which the first wireless device is in an awake mode， an ITO interval for the wireless device to remain in the awake mode based at least in part on the estimated congestion level.

Another apparatus for wireless communication at a station is described. The apparatus may include means for identifying a first activity level in a RF spectrum band used by the first wireless device based at least in part on traffic transmitted to and received by the first wireless device， means for identifying， at the first wireless device， a second activity level in the RF spectrum band based at least in part on transmission and reception activity for at least one second wireless device， means for estimating a congestion level for the RF spectrum based at least in part on the first activity level and the second activity level， and means for determining， for an awake interval in which the first wireless device is in an awake mode， an ITO interval for the wireless device to remain in the awake mode based at least in part on the estimated congestion level.

Another apparatus for wireless communication at a station is described. The apparatus may include a processor， memory in electronic communication with the processor， and instructions stored in the memory. The instructions may be operable to cause the processor to identify a first activity level in a RF spectrum band used by the first wireless device based at least in part on traffic transmitted to and received by the first wireless device， identify， at the first wireless device， a second activity level in the RF spectrum band based at least in part on transmission and reception activity for at least one second wireless device， estimate a congestion level for the RF spectrum based at least in part on the first activity level and the second activity level， and determine， for an awake interval in which the first wireless device is in an awake mode， an ITO interval for the wireless device to remain in the awake mode based at least in part on the estimated congestion level.

Another non-transitory computer readable medium for wireless communication at a station is described. The non-transitory computer-readable medium may include instructions operable to cause a processor to identify a first activity level in a RF spectrum band used by the first wireless device based at least in part on traffic transmitted to and received by the first wireless device， identify， at the first wireless device， a second activity level in the RF spectrum band based at least in part on transmission and reception activity for at least one second wireless device， estimate a congestion level for the RF spectrum based at least in part on the first activity level and the second activity level， and determine， for an awake interval in which the first wireless device is in an awake mode， an ITO interval for the wireless device to remain in the awake mode based at least in part on the estimated congestion level.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates an example of a system for wireless communication at a station (STA) that supports adaptive inactivity timeout management in accordance with aspects of the present disclosure.

FIG. 2 illustrates an example of a wireless network that supports adaptive inactivity timeout management in accordance with aspects of the present disclosure.

FIGs. 3A-3C illustrate example polling procedures that support adaptive inactivity timeout management in accordance with aspects of the present disclosure.

FIGs. 4 through 6 show block diagrams of a device that supports adaptive inactivity timeout management in accordance with aspects of the present disclosure.

FIG. 7 illustrates a block diagram of a system including a STA that supports adaptive inactivity timeout management in accordance with aspects of the present disclosure.

FIGs. 8 through 14 illustrate methods for adaptive inactivity timeout management in accordance with aspects of the present disclosure.

DETAILED DESCRIPTION

Aspects of the disclosure are initially described in the context of a wireless network. A station (STA) in a wireless network may employ adaptive inactivity timeout (ITO) management techniques to save power when communicating with or when connected to an access point (AP) . Such techniques may involve a STA going into a sleep mode and periodically waking up and listening for beacons (or other signals from the AP) . In other techniques， the STA may periodically send polling messages to the AP while in sleep mode， and may wake up only when the STA determines that data messages are awaiting transmission from the AP based on the polling.

When the STA wakes up， the STA may remain in awake mode for a given period of time after the last data packet is transmitted or received in order to ensure that the entire data transmission or reception has been completed. After the given time period， known as an ITO interval， the STA may go back into sleep mode. In some cases， if the AP serving the STA is also serving other STAs or mobile devices， there may be a delay in transmission from the AP to the STA， and the STA may go back into sleep mode prior to receiving the entire transmission from the AP. As the congestion of the network increases， transmission to the STA may be further delayed， which may cause the STA to miss data packets. This may lead to a lower effective throughput for the network， as data packets intended for the STA were not received.

Further， in some instances， a STA may go into sleep mode prior to being assigned to a particular multi-user (MU) group. In such cases， the STA may be seen as a single user (SU) from the perspective of the AP and instead of only transmitting data to the users in an MU group， the AP may also have to additionally transmit data (and in some cases， the same data) to the STA because it is seen as a separate SU entity by the AP. This may also lead to lower effective throughput for the network.

In other situations， an AP may schedule or transmit data to multiple STAs in a round-robin technique where the AP transmits a message (e.g.， in a unicast transmission) to one STA before moving on to transmit another message to a second STA. The AP may continue in this manner until all messages have been transmitted to each STA. If multiple STAs are awaiting messages during their respective ITO intervals， the STAs to which the AP transmits last may go into sleep mode (e.g.， due to expiration of the ITO interval) prior to AP transmission (or STA reception) . In other cases， the STA having the shortest ITO interval， regardless of when it is scheduled to receive transmission， may go into sleep mode prior to AP transmission.

Thus， in some examples， a STA may employ techniques that adaptively determine ITO intervals based on network congestion， radio frequency (RF) spectrum band (2.4 Gigahertz (GHz) ， 5 GHz， 60 GHz， etc. ) ， and/or the bandwidth mode of operation (20 Megahertz (MHz) ， 40 MHz， 80 MHz， etc. ) . For example， the determined ITO interval may vary depending on congestion level， RF spectrum band， and/or the bandwidth mode of operation used by the STA. The ITO interval may be selected from a look-up table (LUT) based on the aforementioned factors.

The STA may also consider sounding sequences to determine whether data may be transmitted to the STA in the future. Based on the sounding sequences or an interval between sounding sequences， the STA may adjust a currently determined ITO or select a new ITO (e.g.， from a LUT) .

In some examples， congestion level may be determined based on different activity levels within the wireless network. For instance， the congestion level may be determined based on the activity level of all other devices， in the wireless network， which may be referred to as other activity. The activity level for the other devices in the wireless network may include transmission and reception of data and control information， and so on， for other devices and STAs in the wireless network that operate in the RF spectrum band. Other congestion metrics， as measured at a given STA’s receiver， may include uplink traffic， downlink traffic， the STA’s basic service set (BSS) traffic (MyBSS traffic) ， and/or other BSS (OBSS) traffic. The congestion level may also be based on the amount of data transmitted to and received by， or the number of received frames at， the given STA， which may be referred to as STA reception activity. In some cases， the congestion level may also include a scaling coefficient for the other activity level and/or the STA reception activity. The scaling coefficient may vary depending on network conditions or other factors. In some cases， the scaling coefficient may favor scaling the other activity level over the STA reception activity in determining the congestion， for example where the STA reception activity is expected to be low.

Additional adaptive inactivity timeout management techniques that may save power are also described that involve determining when a STA should stop polling an AP. For example， in a sleep mode， a STA may speculatively poll an AP to determine whether there is data in queue at the AP to be transmitted to the STA. If the STA receives a number of null data messages (e.g.， indicating no data intended for the STA is in the queue at the AP) in response to the polling or if the STA experiences a number of poll timeouts， the STA may cease polling the AP， which may save power. Further， in some examples， depending on the number of null data messages or poll timeouts， a STA may vary the interval between polls to help prevent unnecessary polling of the AP if the AP has not been responding to the polls. Additionally or alternatively， depending on the number of null data messages or poll timeouts， a STA may vary the number of polls (e.g.， reduce the number of polls to help prevent unnecessary polling of the AP if the AP has not been responding to the polls) .

Aspects of the disclosure are further illustrated by and described with reference to apparatus diagrams， system diagrams， and flowcharts that relate to adaptive inactivity timeout management.

FIG. 1 illustrates a wireless local area network (WLAN) 100 (also known as a Wi-Fi network) configured in accordance with various aspects of the present disclosure. The WLAN 100 may include an AP 105 and multiple associated STAs 115， which may represent devices such as mobile stations， personal digital assistant (PDAs) ， other handheld devices， netbooks， notebook computers， tablet computers， laptops， display devices (e.g.， TVs， computer monitors， etc. ) ， printers， etc. The AP 105 and the associated STAs 115 may represent a basic service set (BSS) or an extended service set (ESS) . The various STAs 115 in the network are able to communicate with one another through the AP 105. Also shown is a coverage area 110 of the AP 105， which may represent a basic service area (BSA) of the WLAN 100. An extended network station (not shown) associated with the WLAN 100 may be connected to a wired or wireless distribution system that may allow multiple APs 105 to be connected in an ESS. In some cases， the WLAN 100 may support adaptive ITO management in which a STA 115 may determine a respective ITO interval based on network congestion， RF spectrum band， or bandwidth mode of operation. The congestion level may be based on different activity levels within the WLAN 100 and the ITO may be determined for a current or subsequent awake interval. In other examples， a STA 115 may modify timing or an interval between polling messages transmitted from the STA 115 to the AP 105.

Although not shown in FIG. 1， a STA 115 may be located in the intersection of more than one coverage area 110 and may associate with more than one AP 105. A single AP 105 and an associated set of STAs 115 may be referred to as a BSS. An ESS is a set of connected BSSs. A distribution system (not shown) may be used to connect APs 105 in an ESS. In some cases， the coverage area 110 of an AP 105 may be divided into sectors (also not shown) . The WLAN 100 may include APs 105 of different types (e.g.， metropolitan area， home network， etc. ) ， with varying and overlapping coverage areas 110. Two STAs 115 may also communicate directly via a direct wireless link 125 regardless of whether both STAs 115 are in the same coverage area 110. Examples of direct wireless links 120 may include Wi-Fi Direct connections， Wi-Fi Tunneled Direct Link Setup (TDLS) links， and other group connections. STAs 115 and APs 105 may communicate according to the WLAN radio and baseband protocol for physical and MAC layers from IEEE 802.11 and versions including， but not limited to， 802.11b， 802.11g， 802.11a， 802.11n， 802.11ac， 802.11ad， 802.11ah， 802.11ax， 802.11az， 802.11ba， etc. In other implementations， peer-to-peer connections or ad hoc networks may be implemented within WLAN 100.

In some cases， a STA 115 (or an AP 105) may be detectable by a central AP 105， but not by other STAs 115 in the coverage area 110 of the central AP 105. For example， one STA 115 may be at one end of the coverage area 110 of the central AP 105 while another STA 115 may be at the other end. Thus， both STAs 115 may communicate with the AP 105， but may not receive the transmissions of the other. This may result in colliding transmissions for the two STAs 115 in a contention based environment (e.g.， channel sense multiple access (CSMA) /CA) because the STAs 115 may not refrain from transmitting on top of each other. A STA 115 whose transmissions are not identifiable， but that is within the same coverage area 110 may be known as a hidden node. CSMA/CA may be supplemented by the exchange of a request to send (RTS) packet transmitted by a sending STA 115 (or AP 105) and a clear to send (CTS) packet transmitted by the receiving STA 115 (or AP 105) . This may alert other devices within range of the sender and receiver not to transmit for the duration of the primary transmission. Thus， RTS/CTS may help mitigate a hidden node problem.

If a STA 115 enters a sleep mode， it may wake periodically to receive a delivery traffic indication message (DTIM) . The STA 115 may wake sufficiently early to activate the radio components used for DTIM reception. In some cases， the STA 115 may also wake early to account for possible timing asynchronization with the AP 105. If the DTIM is not received at the expected time， the STA 115 may wait for a beacon miss timer to expire. If a DTIM (or a standard TIM) is received， the STA 115 may then wait for the indicated transmission until a content after beacon (CAB) timer expires. If either timer expires， the STA 115 may re-enter sleep mode and wait for the next anticipated DTIM or beacon.

FIG. 2 illustrates an example of a wireless network 200 for adaptive inactivity timeout management in accordance with various aspects of the present disclosure. In FIG. 2， AP 105-a supports communication in different coverage areas 110. In some examples， coverage areas 110 may support different RF spectrum bands or different bandwidth modes of operation， which may be associated with a particular RF spectrum band. For example， AP 105-a may support communication in a 5 GHz spectrum band and an 80 MHz mode of operation in coverage area 110-a. In coverage area 110-b， AP 105-a may support communication in a 900 MHz spectrum band and a 20 MHz mode of operation. In other cases， AP 105-a may support the same spectrum band in each of coverage area 110-a and 110-b， but may support different bandwidth modes of operations. For example， AP 105-a may support a 160 MHz mode of operation in coverage area 110-a and may support a 40 MHz mode of operation in coverage area 110-b. Further still， AP 105-a may support multiple RF spectrum bands and/or multiple bandwidth modes of operation in coverage areas 110. Other RF spectrum bands and bandwidth modes of operation may be considered without departing from the scope of the present disclosure.

As shown， AP 105-a is serving multiple STAs (e.g.， STA 115-a， 115-b， 115-c， and 115-d) within coverage area 110-a. In addition， AP 105-a is shown serving STAs 115-e and 115-f located within coverage area 110-b. In some cases， a STA 115 may employ power saving techniques and may consequently enter a sleep mode. For example， STAs 115-a and 115-f may be low-power devices (e.g.， a machine type communications (MTC) device or a device operating on battery power) ， which may enter sleep mode and periodically wake up to listen for a beacon from AP 105-a (or another AP， not shown) indicating that data may be available to transmit. In some cases， the beacon may be a DTIM beacon and may be periodically transmitted by the AP 105-a or may only be transmitted by the AP 105-a when data is queued at AP 105-a.

In some examples， the STAs 115-a through 115-f may remain awake for the duration of a respective ITO interval， which may be calculated based on congestion level as well as an RF spectrum band or an associated bandwidth mode of operation (e.g.， via STAs 115-a through 115-f referencing a lookup table considering their respective congestion level， RF spectrum band， and/or associated bandwidth mode of operation) . For instance， STA 115-a may determine an ITO interval based on congestion level of coverage area 110-a， which includes multiple devices (STAs 115-b， 115-c， and 115-d) . An ITO interval may also be determined by STA 115-f located in coverage area 110-b. In this case， the congestion determined by STA 115-f may be less than the congestion determined by STA 115-a as STA 115-a is operating in coverage area 110-a having more STAs 115 compared to the number of STAs 115 operating in coverage area 110-b. In turn， STA 115-a may determine a longer ITO interval compared to STA 115-f due to the possibility of higher congestion causing further transmission delays. For example， STA 115-a may determine the ITO interval to be 25ms， whereas STA 115-f may determine the ITO interval to be 15ms.

In some examples， congestion level may be determined based on transmission frame count or reception frame count associated with a given STA 115. The congestion level may also be determined based on other activity on a particular channel or within the network. For instance， if a STA 115 has a high number of reception frames， it may indicate that the STA 115 is receiving a lot of data. In such instances， even if the congestion of other activity on the network is relatively low， because the STA 115 is experiencing a high number of reception frames， the congestion level may be determined to be greater than if the congestion level were determined based only on other activity， which may also lead to a different ITO interval determination by a given STA. In some cases， the congestion level may be determined based on a weighted factor or scaling associated with the other activity and the STA reception activity. For instance， in some circumstances， the STA reception activity may be weighted higher than the other activity on the channel or network， which may have a greater influence on the determined congestion level. Alternatively， other activity may be weighted more than STA reception activity and thus， the other activity may have a greater influence on the determined congestion level.

The ITO interval for STAs 115-a and 115-f may also be determined based on RF spectrum band. For example， in some cases， the congestion determined by STA 115-a and 115-f may be similar， as both STAs 115-a and 115-f are communicating with the same AP 105-a. In such instances， the ITO interval determined by STA 115-a may be different than the ITO interval determined by STA 115-f based on different RF spectrum bands or different bandwidth modes of operation. For example， STA 115-f may be communicating in a 5 GHz spectrum band and STA 115-a may be communicating in a 2.4 GHz spectrum band. In such case， STA 115-f may determine a longer ITO interval than STA 115-a.

In another example， STA 115-f may be communicating in the same band as STA 115-a， but may utilize a different bandwidth mode of operation. For instance， STA 115-a and STA 115-f may both operate in a 900 MHz spectrum band， but STA 115-a may support a 20 MHz bandwidth mode of operation， while STA 115-f supports a 40 MHz bandwidth mode of operation. In such instances， STA 115-a and STA 115-f may determine different respective ITO intervals. For example， STA 115-a may determine an ITO interval to be 50ms， while STA 115-f may determine a respective ITO interval to be 100ms.

In some cases， AP 105-a may transmit a sounding sequence to a STA (e.g.， STA 115-a) ， indicating data may be transmitted to STA 115-a in the near future. In such cases， STA 115-a may consider the number of sounding sequences received from the AP 105-a， or the interval between received sounding sequences when determining the ITO interval. In some examples， the ITO interval may be determined based on whether the interval between sounding sequences crosses a threshold or if the number of received sounding sequences crosses a threshold (e.g.， based on whether the received sounding sequence interval spacing exceeds a threshold or if the number of received sounding sequences exceeds a threshold) . For instance， if the interval between consecutive sounding sequences shows an increasing trend， it may be an indication that less data is expected to be transmitted to STA 115-a and thus， a shorter ITO interval may be determined.

The ITO interval may also be determined for a current awake interval or a subsequent awake interval. For example， the ITO interval may be determined for a current awake state prior to entering sleep mode. In some cases， the ITO may be continuously or periodically determined (e.g.， after a given interval of time has passed) . For instance， instead using the determined ITO interval in a subsequent awake interval， the ITO interval may be used in a current awake interval as determined based on congestion in the current awake interval. Thus， the ITO interval may be proactively adjusted， selected， or determined in order to accommodate changing network congestion.

FIGs. 3A-3C illustrate examples of polling for adaptive inactivity timeout management in accordance with various aspects of the present disclosure. FIGs. 3A-3C may represent aspects of techniques performed by a STA 115 as described above with reference to FIGs. 1 and 2. FIG. 3A illustrates a polling procedure at a STA 115 that may save power.

In FIG. 3A， a STA listens for and receives a DTIM beacon 305-a， which may be transmitted to the STA from an AP. The DTIM beacon 305-a may indicate that the AP has data packets to be transmitted to the STA.

Based on the DTIM beacon 305-a， the STA transmits a power saving poll (PS-Poll) message 310-a to the AP during a network sleep interval 335 indicating that the STA is ready to receive the queued data packets from the AP. The AP responds to the PS-Poll message 310-a with the data packet (s) and indicates that more data is awaiting transmission to the STA. As such， the STA enters an awake interval 330-a for an ITO interval 315-a (e.g.， as determined based on the techniques described with reference to FIGs. 1 and 2) in order to receive the data from the AP. After the last transmission is received and after the ITO interval has expired， the STA enters sleep mode during sleep interval 335-a. During sleep mode in the sleep interval 335-a， the STA may send a speculative PS-Poll (SPEC PS-Poll) 320-a to the AP to determine whether data is available at the AP for transmission to the STA. As shown in FIG. 3A， the AP responds to the SPEC PS-Poll 320-a and indicates that more data is available for transmission， and the STA wakes up for an awake interval 330-b until expiration of ITO interval 315-b.

During sleep interval 335-b， the STA may transmit another SPEC PS-Poll to the AP at 320-b and the AP responds indicating that there is no additional data to transmit. Accordingly， the STA remains in sleep mode and then subsequently listens for beacon 325-a， which in this example indicates that no data is available for transmission.

In some cases an AP may not respond to PS-Poll or SPEC PS-Poll transmitted by a STA. For example， a STA may have travelled outside the coverage area of the AP， and may no longer be capable of receiving message from the AP. The AP may experience a number of issues or the network may have a high congestion. It may be beneficial to modify the polling procedure at a STA based on responses or lack thereof from the AP as continuing to poll the AP may be an unnecessary waste of power.

In FIG. 3B， a STA listens for and receives a DTIM beacon 305-b， which may be transmitted to the STA from an AP. The DTIM beacon 305-b may indicate that the AP has data packets to be transmitted to the STA.

Based on the DTIM beacon 305-b， the STA transmits a PS-Poll message 310-b to the AP during a network sleep interval 335-c while in a sleep mode indicating that the STA is ready to receive queued data packets from the AP. The AP responds to the PS-Poll message 310-b with the data packet (s) and indicates that more data is awaiting transmission to the STA. As such， the STA remains in an awake mode for the duration of an ITO interval 315-c (e.g.， as determined based on the techniques described with reference to FIGs. 1 and 2) in order to receive additional data from the AP. After the last transmission of the additional data is received and after the ITO interval has expired， the STA enters sleep mode during sleep interval 335-d. During sleep mode， the STA may send a SPEC PS-Poll 320-c to the AP to determine whether data is available at the AP for transmission to the STA. The AP may respond to the SPEC PS-Poll 320-c and indicate that no additional data is available for transmission.

At 340-a， the STA transmits another SPEC PS-Poll to the AP to determine whether data is available at the AP for transmission to the STA. In this case， the STA receives a null message from the AP or the AP does not respond to the SPEC PS-Poll after response from the AP after a response timer has timed out. Thereafter， the STA transmits another SPEC PS-Poll at 340-b， and again receives no response or a null message. After another SPEC PS-Poll is transmitted at 340-c without a response or a null message， the STA stops polling the AP for the remainder of sleep interval 345. In such cases， instead of continuing to poll the AP with SPEC PS-Polls， once the STA receives a threshold number of null messages from the AP or experiences a threshold number of poll timeouts， the STA saves power by remaining in sleep mode until the next beacon 325-b， when the STA receives beacon 325-b. While three non-responsive or timeouts are shown in this example， other thresholds may be considered without departing from the scope of the present disclosure and in some cases， the threshold number may be determined based on the interval between beacons 305-b and 325-b. For instance， if the interval between beacons 305-b and 325-b is less than 200ms， the threshold may be two， whereas if the interval between beacons 305-b and 325-b is greater than 200ms， the threshold may be three or more.

In some examples， the interval between polling may be based on the duration between beacons or the number of null messages or timeouts， as shown in FIG. 3C. In FIG. 3C， a STA enters sleep mode at 350 and sends a SPEC PS-Poll 320-d after duration T1. As shown， the AP responds to the SPEC PS-Poll indicating that no additional data is available for transmission. After the same duration T1 (e.g.， periodically) ， the STA sends another SPEC PS-Poll 340-d. In this case， the AP does not respond (poll timeout) or the AP responds with a null message. Based on the null message or the lack of response from the AP， the STA may determine to transmit the next SPEC PS-Poll after a larger interval T2. In some cases， interval T2 may be calculated based on the time remaining (TR1) until the next beacon 325-b. For example， T2 may be calculated to be the greater of T1 or TR1/2. In another example， if TR1 exceeds a given predetermined threshold (e.g.， 200ms， 300ms， etc. ) ， T2 may be calculated to be， for example， TR1/3， TR1/4， etc.

After interval T2， STA sends a SPEC PS-Poll 320-e and receives a response from the AP indicating that no additional data is available for transmission. As the AP responded to the SPEC PS-Poll 320-e， the STA may determine that the next SPEC PS-Poll 340-e is to be transmitted after interval T1. In this instance， the AP does not respond to SPEC PS-Poll 340-e or the AP transmitted a null message. As such， the STA may determine to send the next SPEC PS-Poll 340-f after interval T3. The interval T3 may be determined based on the time remaining (TR2) until the next beacon 325-b or may be calculated similar to T1 above. After the interval T3， the STA transmits another SPEC PS-Poll 340-f， which also receives no response or a null message from the AP. In this case， as the time remaining until the next beacon 325-b is less than T1， the STA determines not to send another SPEC PS-Poll.

Though only the above examples are disclosed herein， it should be understood that various other examples may be used when determining the interval between PS-Polls or SPEC PS-Polls by analogy， without departing from the scope of the present disclosure.

FIG. 4 shows a block diagram 400 of a wireless device 405 that supports adaptive inactivity timeout management in accordance with various aspects of the present disclosure. Wireless device 405 may be an example of aspects of a STA 115 as described with reference to FIG. 1. Wireless device 405 may include receiver 410， adaptive inactivity timeout manager 415， and transmitter 420. Wireless device 405 may also include a processor. Each of these components may be in communication with one another (e.g.， via one or more buses) .

Receiver 410 may receive information such as packets， user data， or control information associated with various information channels (e.g.， control channels， data channels， and information related to adaptive inactivity timeout management， etc. ) .Information may be passed on to other components of the device. The receiver 410 may be an example of aspects of the transceiver 735 described with reference to FIG. 7.

Adaptive inactivity timeout manager 415 may be an example of aspects of the adaptive inactivity timeout manager 715 described with reference to FIG. 7. Adaptive inactivity timeout manager 415 may communicate with an AP in a wireless communications network during awake intervals in which the wireless device is in an awake mode， identify a (RF spectrum band used by the wireless device to communicate with the AP， determine a congestion level associated with the RF spectrum band， and determine， for an awake interval of the awake intervals， an ITO interval for the wireless device to remain in the awake mode based on the identified RF spectrum band and the determined congestion level.

The adaptive inactivity timeout manager 415 may also determine a DTIM period and poll an AP during the DTIM period while the station is in a sleep mode. The adaptive inactivity timeout manager 415 may identify that a trigger condition has been satisfied. The trigger condition may be based on a determination that at least one null data message has been received from the AP， a predetermined threshold number of polls have timed out， or a combination thereof. The adaptive inactivity timeout manager 415 may then modify a timing for the station to poll the AP based on identifying that the trigger condition has been satisfied.

The adaptive inactivity timeout manager 415 may also identify a first activity level in a RF spectrum band used by the first wireless device based on traffic transmitted to and received by the first wireless device. The adaptive inactivity timeout manager 415 may then identify， at the first wireless device， a second activity level in the RF spectrum band based on transmission and reception activity for at least one second wireless device and estimate a congestion level for the RF spectrum based on the first activity level and the second activity level. The adaptive inactivity timeout manager 415 may then determine， for an awake interval in which the first wireless device is in an awake mode， an ITO interval for the wireless device to remain in the awake mode based on the estimated congestion level.

Transmitter 420 may transmit signals generated by other components of the device. In some examples， the transmitter 420 may be collocated with a receiver 410 in a transceiver module. For example， the transmitter 420 may be an example of aspects of the transceiver 735 described with reference to FIG. 7. The transmitter 420 may include a single antenna， or it may include a set of antennas.

FIG. 5 shows a block diagram 500 of a wireless device 505 that supports adaptive inactivity timeout management in accordance with various aspects of the present disclosure. Wireless device 505 may be an example of aspects of a wireless device 405 or a STA 115 as described with reference to FIGs. 1 and 4. Wireless device 505 may include receiver 510， adaptive inactivity timeout manager 515， and transmitter 520. Wireless device 505 may also include a processor. Each of these components may be in communication with one another (e.g.， via one or more buses) .

Receiver 510 may receive information such as packets， user data， or control information associated with various information channels (e.g.， control channels， data channels， and information related to adaptive inactivity timeout management， etc. ) . Information may be passed on to other components of the device. The receiver 510 may be an example of aspects of the transceiver 735 described with reference to FIG. 7.

Adaptive inactivity timeout manager 515 may be an example of aspects of the adaptive inactivity timeout manager 715 described with reference to FIG. 7. Adaptive inactivity timeout manager 515 may also include communications manager 530， RF band component 535， congestion component 540， ITO component 545， DTIM component 550， polling component 555， and trigger component 560.

Communications manager 530 may communicate with an AP in a wireless communications network during awake intervals in which the wireless device is in an awake mode. In some cases， the station and the AP operate according to at least a MU-MIMO mode， or a SU-MC mode， or a combination thereof.

RF band component 535 may identify a RF spectrum band used by the wireless device to communicate with the AP. In some cases， identifying the RF spectrum band used by the wireless device includes identifying a bandwidth mode of operation used by the wireless device to communicate with the AP.

In some cases， the bandwidth mode of operation includes a 20 megahertz (MHz) bandwidth mode， or a 40 MHz bandwidth mode， or an 80 MHz bandwidth mode， or a 160 MHz bandwidth mode， or an 80+80 MHz bandwidth mode， or a combination thereof. In some cases， identifying the RF spectrum band used by the wireless device includes identifying an RF spectrum range associated with the wireless communications network that is used by the wireless device to communicate with the AP. In some cases， the RF spectrum range used by the wireless communications network is associated with at least a 2.4 gigahertz (GHz) spectrum， or a 5 GHz spectrum， or a 900 MHz spectrum， or a 60 GHz spectrum.

Congestion component 540 may determine a congestion level associated with the RF spectrum band， identify a first activity level in a radio frequency (RF) spectrum band used by the first wireless device based on traffic transmitted to and received by the first wireless device， identify， at the first wireless device， a second activity level in the RF spectrum band based on transmission and reception activity for at least one second wireless device， and estimate a congestion level for the RF spectrum based on the first activity level and the second activity level.

In some cases， determining the congestion level associated with the RF spectrum band includes determining the congestion level associated with the RF spectrum band during a first awake interval. In some cases， the congestion level is determined based on data received by the station in the RF spectrum band. In some cases， the congestion level is further determined based on other activity in the wireless communications network in the RF spectrum band. In some cases， estimating the congestion level includes scaling the first and second activity levels by applying a scaling coefficient associated with the awake interval， and estimating the congestion level for the RF spectrum band based on the scaled first and second activity levels.

In some cases， the traffic transmitted to and received by the first wireless device includes unicast data transmitted to the first wireless device. In some cases， the transmission and reception activity for the at least one second wireless device includes a measurement of all wireless communications network activities in the RF spectrum band other than transmission and reception traffic associated with the first wireless device.

ITO component 545 may determine， for an awake interval of the awake intervals， an ITO interval for the wireless device to remain in the awake mode based on the identified RF spectrum band and the determined congestion level， increase the ITO interval for the wireless device to remain in the awake mode， and determine， for an awake interval in which the first wireless device is in an awake mode， an ITO interval for the wireless device to remain in the awake mode based on the estimated congestion level.

In some cases， determining the ITO interval includes determining the ITO interval for the wireless device to remain in the awake mode during the first awake interval， or a subsequent awake interval， or a combination thereof. In some cases， determining the ITO interval includes receiving multiple sounding triggers， determining intervals between sounding triggers of the received multiple sounding sequences， and determining the ITO based on the determined intervals. In some cases， determining the ITO interval includes determining that the congestion level associated with the RF spectrum band is greater than a predetermined threshold for the identified RF spectrum band.

DTIM component 550 may determine a DTIM period.

Polling component 555 may poll an AP during the DTIM period and while the station is in a sleep mode， revert to polling the AP during a second DTIM period according to a default timing. Polling component 555 may modify the default timing for the station to poll the AP based on a second identification that the trigger condition has been satisfied during the second DTIM period and resume polling the AP during an immediately subsequent DTIM period， modify a timing for the station to poll the AP based on identifying that the trigger condition has been satisfied. Polling component 555 may identify， for a set of polls sent from the station to the AP， a percentage of the set of polls that have timed out， and disable modifying the timing for the station to poll the AP based on a determination that the percentage is greater than a predetermined threshold.

In some cases， polling the AP includes transmitting multiple speculative PS-Polls to the AP at a set of intervals based on the determined DTIM period. In some cases， modifying the timing includes identifying a remaining portion of the DTIM period， and stopping polling the AP for the remaining portion of the DTIM period. In some cases， modifying the timing includes identifying a consecutive number of polls sent from the station to the AP that have timed out， and disabling polling for the station based on a determination that the consecutive number of polls is greater than a predetermined threshold. In some cases， polling the AP includes transmitting multiple PS-Polls to the AP at a set of intervals based on the number of null messages received from the AP or the threshold number of polls having timed out. In some cases， modifying the timing includes adjusting a time interval between polls that the station transmits to the AP.

Trigger component 560 may identify that a trigger condition has been satisfied， where the trigger condition is based on a determination that at least one null data message has been received from the AP， or a predetermined threshold number of polls have timed out， or a combination thereof.

Transmitter 520 may transmit signals generated by other components of the device. In some examples， the transmitter 520 may be collocated with a receiver 510 in a transceiver module. For example， the transmitter 520 may be an example of aspects of the transceiver 735 described with reference to FIG. 7. The transmitter 520 may include a single antenna， or it may include a set of antennas.

FIG. 6 shows a block diagram 600 of an adaptive inactivity timeout manager 615 that supports adaptive inactivity timeout management in accordance with various aspects of the present disclosure. The adaptive inactivity timeout manager 615 may be an example of aspects of an adaptive inactivity timeout manager 415， an adaptive inactivity timeout manager 515， or an adaptive inactivity timeout manager 715 described with reference to FIGs. 4， 5， and 7. The adaptive inactivity timeout manager 615 may include communications manager 620， RF band component 625， congestion component 630， ITO component 635， DTIM component 640， polling component 645， trigger component 650， AP list component 655， association component 660， and block ACK component 665. Each of these modules may communicate， directly or indirectly， with one another (e.g.， via one or more buses) .

Communications manager 620 may communicate with an AP in a wireless communications network during awake intervals in which the wireless device is in an awake mode. In some cases， the station and the AP operate according to at least a multi-user multiple input multiple output (MU-MIMO) mode， or a single-user multi-client (SU-MC) mode， or a combination thereof.

RF band component 625 may identify a radio frequency (RF) spectrum band used by the wireless device to communicate with the AP. Congestion component 630 may determine a congestion level associated with the RF spectrum band， identify a first activity level in a RF spectrum band used by the first wireless device based on traffic transmitted to and received by the first wireless device， identify， at the first wireless device， a second activity level in the RF spectrum band based on transmission and reception activity for at least one second wireless device， and estimate a congestion level for the RF spectrum based on the first activity level and the second activity level.

ITO component 635 may determine， for an awake interval of the awake intervals， an ITO interval for the wireless device to remain in the awake mode based on the identified RF spectrum band and the determined congestion level， increase the ITO interval for the wireless device to remain in the awake mode， and determine， for an awake interval in which the first wireless device is in an awake mode， an ITO interval for the wireless device to remain in the awake mode based on the estimated congestion level.

DTIM component 640 may determine a DTIM period.

Polling component 645 may poll an AP during the DTIM period and while the station is in a sleep mode， revert to polling the AP during a second DTIM period according to a default timing. Polling component 645 may modify the default timing for the station to poll the AP based on a second identification that the trigger condition has been satisfied during the second DTIM period and resume polling the AP during an immediately subsequent DTIM period. Polling component 645 may modify a timing for the station to poll the AP based on identifying that the trigger condition has been satisfied， identify， for a set of polls sent from the station to the AP， a percentage of the set of polls that have timed out， and disable modifying the timing for the station to poll the AP based on a determination that the percentage is greater than a predetermined threshold.

Trigger component 650 may identify that a trigger condition has been satisfied， where the trigger condition is based on a determination that at least one null data message has been received from the AP， or a predetermined threshold number of polls have timed out， or a combination thereof.

AP list component 655 may add the AP to a list of APs for which the station has modified timing and remove the AP from the list upon expiration of an aging factor associated with the AP.

Association component 660 may reassociate the station with the AP after modifying the timing for the station to poll the AP.

Block ACK component 665 may delete a first block ACK session based on a determination that the percentage is greater than a predetermined threshold and activate a second block ACK session with the AP after deleting the first block ACK session.

FIG. 7 shows a diagram of a system 700 including a device 705 that supports adaptive inactivity timeout management in accordance with various aspects of the present disclosure. Device 705 may be an example of or include the components of wireless device 405， wireless device 505， or a STA 115 as described above， e.g.， with reference to FIGs. 1， 4 and 5. Device 705 may include components for bi-directional voice and data communications including components for transmitting and receiving communications， including adaptive inactivity timeout manager 715， processor 720， memory 725， software 730， transceiver 735， antenna 740， and I/O controller 745.

Processor 720 may include an intelligent hardware device， (e.g.， a general-purpose processor， a digital signal processor (DSP) ， a central processing unit (CPU) ， a microcontroller， an application specific integrated circuit (ASIC) ， a field-programmable gate array (FPGA) ， a programmable logic device， a discrete gate or transistor logic component， a discrete hardware component， or any combination thereof) . In some cases， processor 720 may be configured to operate a memory array using a memory controller. In other cases， a memory controller may be integrated into processor 720. Processor 720 may be configured to execute computer-readable instructions stored in a memory to perform various functions (e.g.， functions or tasks supporting adaptive inactivity timeout management) .

Memory 725 may include random access memory (RAM) and read only memory (ROM) . The memory 725 may store computer-readable， computer-executable software 730 including instructions that， when executed， cause the processor to perform various functions described herein. In some cases， the memory 725 may contain， among other things， a Basic Input-Output system (BIOS) which may control basic hardware and/or software operation such as the interaction with peripheral components or devices.

Software 730 may include code to implement aspects of the present disclosure， including code to support adaptive inactivity timeout management. Software 730 may be stored in a non-transitory computer-readable medium such as system memory or other memory. In some cases， the software 730 may not be directly executable by the processor but may cause a computer (e.g.， when compiled and executed) to perform functions described herein.

Transceiver 735 may communicate bi-directionally， via one or more antennas， wired， or wireless links as described above. For example， the transceiver 735 may represent a wireless transceiver and may communicate bi-directionally with another wireless transceiver. The transceiver 735 may also include a modem to modulate the packets and provide the modulated packets to the antennas for transmission， and to demodulate packets received from the antennas.

In some cases， the wireless device may include a single antenna 740. However， in some cases the device may have more than one antenna 740， which may be capable of concurrently transmitting or receiving multiple wireless transmissions.

I/O controller 745 may manage input and output signals for device 705. Input/output control component 745 may also manage peripherals not integrated into device 705. In some cases， input/output control component 745 may represent a physical connection or port to an external peripheral. In some cases， I/O controller 745 may utilize an operating system such as

or another known operating system.

FIG. 8 shows a flowchart illustrating a method 800 for adaptive inactivity timeout management in accordance with various aspects of the present disclosure. The operations of method 800 may be implemented by a STA 115 or its components as described herein. For example， the operations of method 800 may be performed by an adaptive inactivity timeout manager as described with reference to FIGs. 4 through 7. In some examples， a STA 115 may execute a set of codes to control the functional elements of the device to perform the functions described below. Additionally or alternatively， the STA 115 may perform aspects the functions described below using special-purpose hardware.

At block 805 the STA 115 may communicate with an AP in a wireless communications network during awake intervals in which the wireless device is in an awake mode. The operations of block 805 may be performed according to the methods described with reference to FIGs. 1 through 3. In certain examples， aspects of the operations of block 805 may be performed by a communications manager as described with reference to FIGs. 4 through 7.

At block 810 the STA 115 may identify a radio frequency (RF) spectrum band used by the wireless device to communicate with the AP. The operations of block 810 may be performed according to the methods described with reference to FIGs. 1 through 3. In certain examples， aspects of the operations of block 810 may be performed by a RF band component as described with reference to FIGs. 4 through 7.

At block 815 the STA 115 may determine a congestion level associated with the RF spectrum band. The operations of block 815 may be performed according to the methods described with reference to FIGs. 1 through 3. In certain examples， aspects of the operations of block 815 may be performed by a congestion component as described with reference to FIGs. 4 through 7.

At block 820 the STA 115 may determine， for an awake interval of the awake intervals， an ITO interval for the wireless device to remain in the awake mode based on the identified RF spectrum band and the determined congestion level. The operations of block 820 may be performed according to the methods described with reference to FIGs. 1 through 3. In certain examples， aspects of the operations of block 820 may be performed by an ITO component as described with reference to FIGs. 4 through 7.

FIG. 9 shows a flowchart illustrating a method 900 for adaptive inactivity timeout management in accordance with various aspects of the present disclosure. The operations of method 900 may be implemented by a STA 115 or its components as described herein. For example， the operations of method 900 may be performed by an adaptive inactivity timeout manager as described with reference to FIGs. 4 through 7. In some examples， a STA 115 may execute a set of codes to control the functional elements of the device to perform the functions described below. Additionally or alternatively， the STA 115 may perform aspects the functions described below using special-purpose hardware.

At block 905 the STA 115 may determine a DTIM period. The operations of block 905 may be performed according to the methods described with reference to FIGs. 1 through 3. In certain examples， aspects of the operations of block 905 may be performed by a DTIM component as described with reference to FIGs. 4 through 7.

At block 910 the STA 115 may poll an AP during the DTIM period and while the station is in a sleep mode. The operations of block 910 may be performed according to the methods described with reference to FIGs. 1 through 3. In certain examples， aspects of the operations of block 910 may be performed by a polling component as described with reference to FIGs. 4 through 7.

At block 915 the STA 115 may identify that a trigger condition has been satisfied. The trigger condition may be based on a determination that at least one null data message has been received from the AP， or a predetermined threshold number of polls have timed out， or a combination thereof. The operations of block 915 may be performed according to the methods described with reference to FIGs. 1 through 3. In certain examples， aspects of the operations of block 915 may be performed by a trigger component as described with reference to FIGs. 4 through 7.

At block 920 the STA 115 may modify a timing for the station to poll the AP based on identifying that the trigger condition has been satisfied. The operations of block 920 may be performed according to the methods described with reference to FIGs. 1 through 3. In certain examples， aspects of the operations of block 920 may be performed by a polling component as described with reference to FIGs. 4 through 7.

FIG. 10 shows a flowchart illustrating a method 1000 for adaptive inactivity timeout management in accordance with various aspects of the present disclosure. The operations of method 1000 may be implemented by a STA 115 or its components as described herein. For example， the operations of method 1000 may be performed by an adaptive inactivity timeout manager as described with reference to FIGs. 4 through 7. In some examples， a STA 115 may execute a set of codes to control the functional elements of the device to perform the functions described below. Additionally or alternatively， the STA 115 may perform aspects the functions described below using special-purpose hardware.

At block 1005 the STA 115 may determine a DTIM period. The operations of block 1005 may be performed according to the methods described with reference to FIGs. 1 through 3. In certain examples， aspects of the operations of block 1005 may be performed by a DTIM component as described with reference to FIGs. 4 through 7.

At block 1010 the STA 115 may poll an AP during the DTIM period and while the station is in a sleep mode. The operations of block 1010 may be performed according to the methods described with reference to FIGs. 1 through 3. In certain examples， aspects of the operations of block 1010 may be performed by a polling component as described with reference to FIGs. 4 through 7.

At block 1015 the STA 115 may identify that a trigger condition has been satisfied， where the trigger condition is based on a determination that at least one null data message has been received from the AP， or a predetermined threshold number of polls have timed out， or a combination thereof. The operations of block 1015 may be performed according to the methods described with reference to FIGs. 1 through 3. In certain examples， aspects of the operations of block 1015 may be performed by a trigger component as described with reference to FIGs. 4 through 7.

At block 1020 the STA 115 may modify a timing for the station to poll the AP based on identifying that the trigger condition has been satisfied. The operations of block 1020 may be performed according to the methods described with reference to FIGs. 1 through 3. In certain examples， aspects of the operations of block 1020 may be performed by a polling component as described with reference to FIGs. 4 through 7.

At block 1025 the STA 115 may add the AP to a list of APs for which the station has modified timing. The operations of block 1025 may be performed according to the methods described with reference to FIGs. 1 through 3. In certain examples， aspects of the operations of block 1025 may be performed by an AP list component as described with reference to FIGs. 4 through 7.

At block 1030 the STA 115 may remove the AP from the list upon expiration of an aging factor associated with the AP. The operations of block 1030 may be performed according to the methods described with reference to FIGs. 1 through 3. In certain examples， aspects of the operations of block 1030 may be performed by an AP list component as described with reference to FIGs. 4 through 7.

FIG. 11 shows a flowchart illustrating a method 1100 for adaptive inactivity timeout management in accordance with various aspects of the present disclosure. The operations of method 1100 may be implemented by a STA 115 or its components as described herein. For example， the operations of method 1100 may be performed by an adaptive inactivity timeout manager as described with reference to FIGs. 4 through 7. In some examples， a STA 115 may execute a set of codes to control the functional elements of the device to perform the functions described below. Additionally or alternatively， the STA 115 may perform aspects the functions described below using special-purpose hardware.

At block 1105 the STA 115 may determine a DTIM period. The operations of block 1105 may be performed according to the methods described with reference to FIGs. 1 through 3. In certain examples， aspects of the operations of block 1105 may be performed by a DTIM component as described with reference to FIGs. 4 through 7.

At block 1110 the STA 115 may poll an AP during the DTIM period and while the station is in a sleep mode. The operations of block 1110 may be performed according to the methods described with reference to FIGs. 1 through 3. In certain examples， aspects of the operations of block 1110 may be performed by a polling component as described with reference to FIGs. 4 through 7.

At block 1115 the STA 115 may identify that a trigger condition has been satisfied， where the trigger condition is based on a determination that at least one null data message has been received from the AP， or a predetermined threshold number of polls have timed out， or a combination thereof. The operations of block 1115 may be performed according to the methods described with reference to FIGs. 1 through 3. In certain examples， aspects of the operations of block 1115 may be performed by a trigger component as described with reference to FIGs. 4 through 7.

At block 1120 the STA 115 may modify a timing for the station to poll the AP based on identifying that the trigger condition has been satisfied. The operations of block 1120 may be performed according to the methods described with reference to FIGs. 1 through 3. In certain examples， aspects of the operations of block 1120 may be performed by a polling component as described with reference to FIGs. 4 through 7.

At block 1125 the STA 115 may reassociate with the AP after modifying the timing for the station to poll the AP. The operations of block 1125 may be performed according to the methods described with reference to FIGs. 1 through 3. In certain examples， aspects of the operations of block 1125 may be performed by an association component as described with reference to FIGs. 4 through 7.

At block 1130 the STA 115 may revert to polling the AP during a second DTIM period according to a default timing. The operations of block 1130 may be performed according to the methods described with reference to FIGs. 1 through 3. In certain examples， aspects of the operations of block 1130 may be performed by a polling component as described with reference to FIGs. 4 through 7.

At block 1135 the STA 115 may modify the default timing for the station to poll the AP based on a second identification that the trigger condition has been satisfied during the second DTIM period. The operations of block 1135 may be performed according to the methods described with reference to FIGs. 1 through 3. In certain examples， aspects of the operations of block 1135 may be performed by a polling component as described with reference to FIGs. 4 through 7.

FIG. 12 shows a flowchart illustrating a method 1200 for adaptive inactivity timeout management in accordance with various aspects of the present disclosure. The operations of method 1200 may be implemented by a STA 115 or its components as described herein. For example， the operations of method 1200 may be performed by an adaptive inactivity timeout manager as described with reference to FIGs. 4 through 7. In some examples， a STA 115 may execute a set of codes to control the functional elements of the device to perform the functions described below. Additionally or alternatively， the STA 115 may perform aspects the functions described below using special-purpose hardware.

At block 1205 the STA 115 may determine a DTIM period. The operations of block 1205 may be performed according to the methods described with reference to FIGs. 1 through 3. In certain examples， aspects of the operations of block 1205 may be performed by a DTIM component as described with reference to FIGs. 4 through 7.

At block 1210 the STA 115 may poll an AP during the DTIM period and while the station is in a sleep mode. The operations of block 1210 may be performed according to the methods described with reference to FIGs. 1 through 3. In certain examples， aspects of the operations of block 1210 may be performed by a polling component as described with reference to FIGs. 4 through 7.

At block 1215 the STA 115 may identify that a trigger condition has been satisfied， where the trigger condition is based on a determination that at least one null data message has been received from the AP， or a predetermined threshold number of polls have timed out， or a combination thereof. The operations of block 1215 may be performed according to the methods described with reference to FIGs. 1 through 3. In certain examples， aspects of the operations of block 1215 may be performed by a trigger component as described with reference to FIGs. 4 through 7.

At block 1220 the STA 115 may modify a timing for the station to poll the AP based on identifying that the trigger condition has been satisfied. The operations of block 1220 may be performed according to the methods described with reference to FIGs. 1 through 3. In certain examples， aspects of the operations of block 1220 may be performed by a polling component as described with reference to FIGs. 4 through 7.

At block 1225 the STA 115 may identify a remaining portion of the DTIM period， and stopping polling the AP for the remaining portion of the DTIM period. The operations of block 1225 may be performed according to the methods described with reference to FIGs. 1 through 3. In certain examples， aspects of the operations of block 1225 may be performed by a polling component as described with reference to FIGs. 4 through 7.

At block 1230 the STA 115 may resume polling the AP during an immediately subsequent DTIM period. The operations of block 1230 may be performed according to the methods described with reference to FIGs. 1 through 3. In certain examples， aspects of the operations of block 1230 may be performed by a polling component as described with reference to FIGs. 4 through 7.

FIG. 13 shows a flowchart illustrating a method 1300 for adaptive inactivity timeout management in accordance with various aspects of the present disclosure. The operations of method 1300 may be implemented by a STA 115 or its components as described herein. For example， the operations of method 1300 may be performed by an adaptive inactivity timeout manager as described with reference to FIGs. 4 through 7. In some examples， a STA 115 may execute a set of codes to control the functional elements of the device to perform the functions described below. Additionally or alternatively， the STA 115 may perform aspects the functions described below using special-purpose hardware.

At block 1305 the STA 115 may determine a DTIM period. The operations of block 1305 may be performed according to the methods described with reference to FIGs. 1 through 3. In certain examples， aspects of the operations of block 1305 may be performed by a DTIM component as described with reference to FIGs. 4 through 7.

At block 1310 the STA 115 may poll an AP during the DTIM period and while the station is in a sleep mode. The operations of block 1310 may be performed according to the methods described with reference to FIGs. 1 through 3. In certain examples， aspects of the operations of block 1310 may be performed by a polling component as described with reference to FIGs. 4 through 7.

At block 1315 the STA 115 may identify that a trigger condition has been satisfied， where the trigger condition is based on a determination that at least one null data message has been received from the AP， or a predetermined threshold number of polls have timed out， or a combination thereof. The operations of block 1315 may be performed according to the methods described with reference to FIGs. 1 through 3. In certain examples， aspects of the operations of block 1315 may be performed by a trigger component as described with reference to FIGs. 4 through 7.

At block 1320 the STA 115 may modify a timing for the station to poll the AP based on identifying that the trigger condition has been satisfied. The operations of block 1320 may be performed according to the methods described with reference to FIGs. 1 through 3. In certain examples， aspects of the operations of block 1320 may be performed by a polling component as described with reference to FIGs. 4 through 7.

At block 1325 the STA 115 may identify， for a set of polls sent from the station to the AP， a percentage of the set of polls that have timed out. The operations of block 1325 may be performed according to the methods described with reference to FIGs. 1 through 3. In certain examples， aspects of the operations of block 1325 may be performed by a polling component as described with reference to FIGs. 4 through 7.

At block 1330 the STA 115 may disable modifying the timing for the station to poll the AP based on a determination that the percentage is greater than a predetermined threshold. The operations of block 1330 may be performed according to the methods described with reference to FIGs. 1 through 3. In certain examples， aspects of the operations of block 1330 may be performed by a polling component as described with reference to FIGs. 4 through 7.

FIG. 14 shows a flowchart illustrating a method 1400 for adaptive inactivity timeout management in accordance with various aspects of the present disclosure. The operations of method 1400 may be implemented by a STA 115 or its components as described herein. For example， the operations of method 1400 may be performed by an adaptive inactivity timeout manager as described with reference to FIGs. 4 through 7. In some examples， a STA 115 may execute a set of codes to control the functional elements of the device to perform the functions described below. Additionally or alternatively， the STA 115 may perform aspects the functions described below using special-purpose hardware.

At block 1405 the STA 115 may identify a first activity level in a RF spectrum band used by the first wireless device based on traffic transmitted to and received by the first wireless device. The operations of block 1405 may be performed according to the methods described with reference to FIGs. 1 through 3. In certain examples， aspects of the operations of block 1405 may be performed by a congestion component as described with reference to FIGs. 4 through 7.

At block 1410 the STA 115 may identify， at the first wireless device， a second activity level in the RF spectrum band based on transmission and reception activity for at least one second wireless device. The operations of block 1410 may be performed according to the methods described with reference to FIGs. 1 through 3. In certain examples， aspects of the operations of block 1410 may be performed by a congestion component as described with reference to FIGs. 4 through 7.

At block 1415 the STA 115 may estimate a congestion level for the RF spectrum based on the first activity level and the second activity level. The operations of block 1415 may be performed according to the methods described with reference to FIGs. 1 through 3. In certain examples， aspects of the operations of block 1415 may be performed by a congestion component as described with reference to FIGs. 4 through 7.

At block 1420 the STA 115 may determine， for an awake interval in which the first wireless device is in an awake mode， an ITO interval for the wireless device to remain in the awake mode based on the estimated congestion level. The operations of block 1420 may be performed according to the methods described with reference to FIGs. 1 through 3. In certain examples， aspects of the operations of block 1420 may be performed by an ITO component as described with reference to FIGs. 4 through 7.

It should be noted that the methods described above describe possible implementations， and that the operations and the steps may be rearranged or otherwise modified and that other implementations are possible. Furthermore， aspects from two or more of the methods may be combined.

Techniques described herein may be used for various wireless communications systems such as code division multiple access (CDMA) ， time division multiple access (TDMA) ， frequency division multiple access (FDMA) ， orthogonal frequency division multiple access (OFDMA) ， single carrier frequency division multiple access (SC-FDMA) ， and other systems. The terms “system” and “network” are often used interchangeably. A code division multiple access (CDMA) system may implement a radio technology such as CDMA2000， Universal Terrestrial Radio Access (UTRA) ， etc. CDMA2000 covers IS-2000， IS-95， and IS-856 standards. IS-2000 Releases may be commonly referred to as CDMA2000 1X，1X， etc. IS-856 (TIA-856) is commonly referred to as CDMA2000 1xEV-DO， High Rate Packet Data (HRPD) ， etc. UTRA includes Wideband CDMA (WCDMA) and other variants of CDMA. A time division multiple access (TDMA) system may implement a radio technology such as Global System for Mobile Communications (GSM) . An orthogonal frequency division multiple access (OFDMA) system may implement a radio technology such as Ultra Mobile Broadband (UMB) ， Evolved UTRA (E-UTRA) ， IEEE 802.11 (Wi-Fi) ， IEEE 802.16 (WiMAX) ， IEEE 802.20， Flash-OFDM， etc.

The wireless communications system or systems described herein may support synchronous or asynchronous operation. For synchronous operation， the stations may have similar frame timing， and transmissions from different stations may be approximately aligned in time. For asynchronous operation， the stations may have different frame timing， and transmissions from different stations may not be aligned in time. The techniques described herein may be used for either synchronous or asynchronous operations.

The downlink transmissions described herein may also be called forward link transmissions while the uplink transmissions may also be called reverse link transmissions. Each communication link described herein-including， for example， WLAN 100 and wireless network 200 of FIGs. 1 and 2-may include one or more carriers， where each carrier may be a signal made up of multiple sub-carriers (e.g.， waveform signals of different frequencies) .

The description set forth herein， in connection with the appended drawings， describes example configurations and does not represent all the examples that may be implemented or that are within the scope of the claims. The term “exemplary” used herein means “serving as an example， instance， or illustration， ” and not “preferred” or “advantageous over other examples. ” The detailed description includes specific details for the purpose of providing an understanding of the described techniques. These techniques， however， may be practiced without these specific details. In some instances， well-known structures and devices are shown in block diagram form in order to avoid obscuring the concepts of the described examples.

In the appended figures， similar components or features may have the same reference label. Further， various components of the same type may be distinguished by following the reference label by a dash and a second label that distinguishes among the similar components. If just the first reference label is used in the specification， the description is applicable to any one of the similar components having the same first reference label irrespective of the second reference label.

Information and signals described herein may be represented using any of a variety of different technologies and techniques. For example， data， instructions， commands， information， signals， bits， symbols， and chips that may be referenced throughout the above description may be represented by voltages， currents， electromagnetic waves， magnetic fields or particles， optical fields or particles， or any combination thereof.

The various illustrative blocks and modules described in connection with the disclosure herein may be implemented or performed with a general-purpose processor， a DSP， an ASIC， an FPGA or other programmable logic device， discrete gate or transistor logic， discrete hardware components， or any combination thereof designed to perform the functions described herein. A general-purpose processor may be a microprocessor， but in the alternative， the processor may be any conventional processor， controller， microcontroller， or state machine. A processor may also be implemented as a combination of computing devices (e.g.， a combination of a digital signal processor (DSP) and a microprocessor， multiple microprocessors， one or more microprocessors in conjunction with a DSP core， or any other such configuration) .

The functions described herein may be implemented in hardware， software executed by a processor， firmware， or any combination thereof. If implemented in software executed by a processor， the functions may be stored on or transmitted over as one or more instructions or code on a computer-readable medium. Other examples and implementations are within the scope of the disclosure and appended claims. For example， due to the nature of software， functions described above may be implemented using software executed by a processor， hardware， firmware， hardwiring， or combinations of any of these. Features implementing functions may also be physically located at various positions， including being distributed such that portions of functions are implemented at different physical locations. Also， as used herein， including in the claims， “or” as used in a list of items (for example， a list of items prefaced by a phrase such as “at least one of” or “one or more of” ) indicates an inclusive list such that， for example， a list of at least one of A， B， or C means A or B or C or AB or AC or BC or ABC (i.e.， A and B and C) .

Computer-readable media includes both non-transitory computer storage media and communication media including any medium that facilitates transfer of a computer program from one place to another. A non-transitory storage medium may be any available medium that can be accessed by a general purpose or special purpose computer. By way of example， and not limitation， non-transitory computer-readable media can comprise RAM， ROM， electrically erasable programmable read only memory (EEPROM) ， compact disk (CD) ROM or other optical disk storage， magnetic disk storage or other magnetic storage devices， or any other non-transitory medium that can be used to carry or store desired program code means in the form of instructions or data structures and that can be accessed by a general-purpose or special-purpose computer， or a general-purpose or special-purpose processor. Also， any connection is properly termed a computer-readable medium. For example， if the software is transmitted from a website， server， or other remote source using a coaxial cable， fiber optic cable， twisted pair， digital subscriber line (DSL) ， or wireless technologies such as infrared， radio， and microwave， then the coaxial cable， fiber optic cable， twisted pair， DSL， or wireless technologies such as infrared， radio， and microwave are included in the definition of medium. Disk and disc， as used herein， include CD， laser disc， optical disc， digital versatile disc (DVD) ， floppy disk and Blu-ray disc where disks usually reproduce data magnetically， while discs reproduce data optically with lasers. Combinations of the above are also included within the scope of computer-readable media.

The description herein is provided to enable a person skilled in the art to make or use the disclosure. Various modifications to the disclosure will be readily apparent to those skilled in the art， and the generic principles defined herein may be applied to other variations without departing from the scope of the disclosure. Thus， the disclosure is not limited to the examples and designs described herein， but is to be accorded the broadest scope consistent with the principles and novel features disclosed herein.

Claims

A method for wireless communication at a station， comprising：

determining a delivery traffic indication message (DTIM) period；

polling an access point (AP) during the DTIM period and while the station is in a sleep mode；

identifying that a trigger condition has been satisfied， wherein the trigger condition is based at least in part on a determination that at least one null data message has been received from the AP， or a predetermined threshold number of polls have timed out， or a combination thereof； and

modifying a timing for the station to poll the AP and a number of polls during the DTIM period based at least in part on identifying that the trigger condition has been satisfied.
The method of claim 1， further comprising：

adding the AP to a list of APs for which the station has modified timing.
The method of claim 2， further comprising：

removing the AP from the list upon expiration of an aging factor associated with the AP.
The method of claim 1， further comprising：

reassociating with the AP after modifying the timing for the station to poll the AP；

reverting to polling the AP during a second DTIM period according to a default timing； and

modifying the default timing for the station to poll the AP based at least in part on a second identification that the trigger condition has been satisfied during the second DTIM period.
The method of claim 1， wherein modifying the timing comprises：

identifying a remaining portion of the DTIM period； and

stopping polling the AP for the remaining portion of the DTIM period.
The method of claim 5， further comprising：

resuming polling the AP during an immediately subsequent DTIM period.
The method of claim 1， wherein modifying the timing comprises：

adjusting a time interval between polls that the station transmits to the AP.
The method of claim 1， wherein modifying the timing comprises：

identifying a consecutive number of polls sent from the station to the AP that have timed out； and

disabling polling for the station based at least in part on a determination that the consecutive number of polls is greater than a predetermined threshold.
The method of claim 1， further comprising：

identifying， for a plurality of polls sent from the station to the AP， a percentage of the plurality of polls that have timed out； and

disabling modifying the timing for the station to poll the AP based at least in part on a determination that the percentage is greater than a predetermined threshold.
The method of claim 9， further comprising：

deleting a first block acknowledgement (ACK) session based at least in part on a determination that the percentage is greater than a predetermined threshold； and

activating a second block ACK session with the AP after deleting the first block ACK session.
The method of claim 1， wherein polling the AP comprises：

transmitting multiple power saving polls (PS-Polls) to the AP at a plurality of intervals based at least in part on the number of null messages received from the AP or the threshold number of polls having timed out.
The method of claim 1， wherein polling the AP comprises：

transmitting multiple speculative power saving polls (PS-Polls) to the AP at a plurality of intervals based at least in part on the determined DTIM period.
An apparatus for wireless communication， comprising：

means for determining a delivery traffic indication message (DTIM) period；

means for polling an access point (AP) during the DTIM period and while the station is in a sleep mode；

means for identifying that a trigger condition has been satisfied， wherein the trigger condition is based at least in part on a determination that at least one null data message has been received from the AP， or a predetermined threshold number of polls have timed out， or a combination thereof； and

means for modifying a timing for the station to poll the AP and a number of polls during the DTIM period based at least in part on identifying that the trigger condition has been satisfied.
The apparatus of claim 13， further comprising：

means for adding the AP to a list of APs for which the station has modified timing.
The apparatus of claim 14， further comprising：

means for removing the AP from the list upon expiration of an aging factor associated with the AP.
The apparatus of claim 13， further comprising：

means for reassociating with the AP after modifying the timing for the station to poll the AP；

means for reverting to polling the AP during a second DTIM period according to a default timing； and

means for modifying the default timing for the station to poll the AP based at least in part on a second identification that the trigger condition has been satisfied during the second DTIM period.
The apparatus of claim 13， wherein the means for modifying the timing comprises：

means for identifying a remaining portion of the DTIM period； and

means for stopping polling the AP for the remaining portion of the DTIM period.
The apparatus of claim 17， further comprising：

means for resuming polling the AP during an immediately subsequent DTIM period.
The apparatus of claim 13， wherein the means for modifying the timing comprises：

means for adjusting a time interval between polls that the station transmits to the AP.
The apparatus of claim 13， wherein the means for modifying the timing comprises：

means for identifying a consecutive number of polls sent from the station to the AP that have timed out； and

means for disabling polling for the station based at least in part on a determination that the consecutive number of polls is greater than a predetermined threshold.
The apparatus of claim 13， further comprising：

means for identifying， for a plurality of polls sent from the station to the AP， a percentage of the plurality of polls that have timed out； and

means for disabling modifying the timing for the station to poll the AP based at least in part on a determination that the percentage is greater than a predetermined threshold.
The apparatus of claim 21， further comprising：

means for deleting a first block acknowledgement (ACK) session based at least in part on a determination that the percentage is greater than a predetermined threshold； and

means for activating a second block ACK session with the AP after deleting the first block ACK session.
The apparatus of claim 13， wherein the means for polling the AP comprises：

means for transmitting multiple power saving polls (PS-Polls) to the AP at a plurality of intervals based at least in part on the number of null messages received from the AP or the threshold number of polls having timed out.
The apparatus of claim 13， wherein the means for polling the AP comprises：

means for transmitting multiple speculative power saving polls (PS-Polls) to the AP at a plurality of intervals based at least in part on the determined DTIM period.
An apparatus for wireless communication， comprising：

a processor；

memory in electronic communication with the processor； and

instructions stored in the memory and operable， when executed by the processor， to cause the apparatus to：

determine a delivery traffic indication message (DTIM) period；

poll an access point (AP) during the DTIM period and while the station is in a sleep mode；

identify that a trigger condition has been satisfied， wherein the trigger condition is based at least in part on a determination that at least one null data message has been received from the AP， or a predetermined threshold number of polls have timed out， or a combination thereof； and

modify a timing for the station to poll the AP and a number of polls during the DTIM period based at least in part on identifying that the trigger condition has been satisfied.
The apparatus of claim 25， wherein the instructions are further executable by the processor to：

add the AP to a list of APs for which the station has modified timing.
The apparatus of claim 26， wherein the instructions are further executable by the processor to：

remove the AP from the list upon expiration of an aging factor associated with the AP.
The apparatus of claim 25， wherein the instructions are further executable by the processor to：

reassociate with the AP after modifying the timing for the station to poll the AP；

revert to polling the AP during a second DTIM period according to a default timing； and

modify the default timing for the station to poll the AP based at least in part on a second identification that the trigger condition has been satisfied during the second DTIM period.
The apparatus of claim 25， wherein the instructions executable by the processor to modify the timing comprise instructions executable by the processor to：

identify a remaining portion of the DTIM period； and

stop polling the AP for the remaining portion of the DTIM period.
The apparatus of claim 29， wherein the instructions are further executable by the processor to：

resume polling the AP during an immediately subsequent DTIM period.
The apparatus of claim 25， wherein the instructions executable by the processor to modify the timing comprise instructions executable by the processor to：

adjust a time interval between polls that the station transmits to the AP.
The apparatus of claim 25， wherein the instructions executable by the processor to modify the timing comprise instructions executable by the processor to：

identify a consecutive number of polls sent from the station to the AP that have timed out； and

disable polling for the station based at least in part on a determination that the consecutive number of polls is greater than a predetermined threshold.
The apparatus of claim 25， wherein the instructions are further executable by the processor to：

identify， for a plurality of polls sent from the station to the AP， a percentage of the plurality of polls that have timed out； and

disable modifying the timing for the station to poll the AP based at least in part on a determination that the percentage is greater than a predetermined threshold.
The apparatus of claim 33， wherein the instructions are further executable by the processor to：

delete a first block acknowledgement (ACK) session based at least in part on a determination that the percentage is greater than a predetermined threshold； and

activate a second block ACK session with the AP after deleting the first block ACK session.
The apparatus of claim 25， wherein the instructions executable by the processor to poll the AP comprise instructions executable by the processor to：

transmit multiple power saving polls (PS-Polls) to the AP at a plurality of intervals based at least in part on the number of null messages received from the AP or the threshold number of polls having timed out.
The apparatus of claim 25， wherein the instructions executable by the processor to poll the AP comprise instructions executable by the processor to：

transmit multiple speculative power saving polls (PS-Polls) to the AP at a plurality of intervals based at least in part on the determined DTIM period.
A non-transitory computer readable medium storing code for wireless communication， the code comprising instructions executable by a processor to：

determine a delivery traffic indication message (DTIM) period；

poll an access point (AP) during the DTIM period and while the station is in a sleep mode；

identify that a trigger condition has been satisfied， wherein the trigger condition is based at least in part on a determination that at least one null data message has been received from the AP， or a predetermined threshold number of polls have timed out， or a combination thereof； and

modify a timing for the station to poll the AP and a number of polls during the DTIM period based at least in part on identifying that the trigger condition has been satisfied.
The non-transitory computer-readable medium of claim 37， wherein the instructions are further executable by the processor to：

add the AP to a list of APs for which the station has modified timing.
The non-transitory computer-readable medium of claim 38， wherein the instructions are further executable by the processor to：

remove the AP from the list upon expiration of an aging factor associated with the AP.
The non-transitory computer-readable medium of claim 37， wherein the instructions are further executable by the processor to：

reassociate with the AP after modifying the timing for the station to poll the AP；

revert to polling the AP during a second DTIM period according to a default timing； and

modify the default timing for the station to poll the AP based at least in part on a second identification that the trigger condition has been satisfied during the second DTIM period.
The non-transitory computer-readable medium of claim 37， wherein the code comprising instructions executable by a processor to modify the timing comprises instructions further executable by the processor to：

identify a remaining portion of the DTIM period； and

stop polling the AP for the remaining portion of the DTIM period.
The non-transitory computer-readable medium of claim 41， wherein the instructions are further executable by the processor to：

resume polling the AP during an immediately subsequent DTIM period.
The non-transitory computer-readable medium of claim 37， wherein the code comprising instructions executable by a processor to modify the timing comprises instructions further executable by the processor to：

adjust a time interval between polls that the station transmits to the AP.
The non-transitory computer-readable medium of claim 37， wherein the code comprising instructions executable by a processor to modify the timing comprises instructions further executable by the processor to：

identify a consecutive number of polls sent from the station to the AP that have timed out； and

disable polling for the station based at least in part on a determination that the consecutive number of polls is greater than a predetermined threshold.
The non-transitory computer-readable medium of claim 37， wherein the instructions are further executable by the processor to：

identify， for a plurality of polls sent from the station to the AP， a percentage of the plurality of polls that have timed out； and

disable modifying the timing for the station to poll the AP based at least in part on a determination that the percentage is greater than a predetermined threshold.
The non-transitory computer-readable medium of claim 45， wherein the instructions are further executable by the processor to：

delete a first block acknowledgement (ACK) session based at least in part on a determination that the percentage is greater than a predetermined threshold； and

activate a second block ACK session with the AP after deleting the first block ACK session.
The non-transitory computer-readable medium of claim 37， wherein the code comprising instructions executable by a processor to poll the AP comprises instructions executable by a processor to：

transmit multiple power saving polls (PS-Polls) to the AP at a plurality of intervals based at least in part on the number of null messages received from the AP or the threshold number of polls having timed out.
The non-transitory computer-readable medium of claim 37， wherein the code comprising instructions executable by a processor to poll the AP comprises instructions executable by a processor to：

transmit multiple speculative power saving polls (PS-Polls) to the AP at a plurality of intervals based at least in part on the determined DTIM period.