Systems and methods of adaptive power saving for wireless traffic

Disclosed herein are related to dynamically adjusting a wake time and a sleep time for wireless communication between two or more devices to reduce power consumption. In one aspect, a first device enters a wake up state to wirelessly communicate with a second device for a service period with a determined duration scheduled according to a target wake time (TWT) protocol. In one aspect, the first device monitors for one or more indicators from the second device indicating that additional data is available for communication. In one aspect, the first device extends the service period beyond the determined duration, in response to receiving a first indicator of the one or more indicators. In one aspect, the first device communicates with the second device the additional data during the service period extended beyond the determined duration.

FIELD OF DISCLOSURE

The present disclosure is generally related to wireless communication, including but not limited to reducing latency in wireless communication for artificial reality.

BACKGROUND

Artificial reality such as a virtual reality (VR), an augmented reality (AR), or a mixed reality (MR) provides immersive experience to a user. In one example, a user wearing a head wearable display (HWD) can turn the user's head, and an image of a virtual object corresponding to a location of the HWD and a gaze direction of the user can be displayed on the HWD to allow the user to feel as if the user is moving within a space of artificial reality (e.g., a VR space, an AR space, or a MR space).

In one implementation, an image of a virtual object is generated by a console communicatively coupled to the HWD. In one example, the HWD includes various sensors that detect a location and/or orientation of the HWD, and transmits the detected location and/or orientation of the HWD to the console through a wired connection or a wireless connection. The console can determine a user's view of the space of the artificial reality according to the detected location and/or orientation of the HWD, and generate image data indicating an image of the space of the artificial reality corresponding to the user's view. The console can transmit the image data to the HWD, by which the image of the space of the artificial reality corresponding to the user's view can be presented to the user. In one aspect, the process of detecting the location of the HWD and the gaze direction of the user wearing the HWD, and rendering the image to the user should be performed within a frame time (e.g., less than 11 ms). Any latency between a movement of the user wearing the HWD and an image displayed corresponding to the user movement can cause judder, which may result in motion sickness and can degrade the user experience.

SUMMARY

Various embodiments disclosed herein are related to a method for adjusting wireless communication between a first device and a second device. In some embodiments, the method includes entering, by a first device, a wake up state to wirelessly communicate with a second device for a service period with a determined duration scheduled according to a target wake time (TWT) protocol. In some embodiments, the method includes monitoring, by the first device, for one or more indicators from the second device indicating that additional data is available for communication. In some embodiments, the method includes extending, by the first device, the service period beyond the determined duration, in response to receiving a first indicator of the one or more indicators. In some embodiments, the method includes communicating, by the first device with the second device, the additional data during the service period extended beyond the determined duration.

In some embodiments, the method includes entering, by the first device after the service period extended beyond the determined duration, a sleep state until a start time of another service period subsequent to the service period. In some embodiments, the method includes receiving, by the first device, a second indicator of the one or more indicators, after extending the service period. In some embodiments, the method includes determining, by the first device in response to the second indicator, that further extending the service period responsive to the second indicator would exceed a maximum time duration for the service period. In some embodiments, the method includes bypassing, by the first device, the further extending of the service period, in response to the determination that further extending the service period responsive to the second indicator would exceed the maximum time duration.

In some embodiments, the method includes determining, by the first device in response to receiving the first indicator, that further extending the service period responsive to the first indicator would not exceed a maximum time duration for the service period. In some embodiments, the method includes further extending, by the first device, the service period, in response to the determination that further extending the service period responsive to the first indicator would not exceed the maximum time.

In some embodiments, the first indicator is an end of service period (ESOP) bit, a buffer status report (BSR) bit, or a more data field value. In some embodiments, the method includes performing, by the first device, a periodic adjustment of one or more parameters, the one or more parameters including at least one of a start time of a first service period, a duration of the first service period, or a duration between the start time of the first service period and a start time of a second service period subsequent to the first service period. In some embodiments, a frequency of the periodic adjustment is based on a difference between i) a resolution of a first clock of the first device, based on which an image frame is generated, and ii) a resolution of a second clock of the first device, based on which wireless communication with the second device is performed. In some embodiments, performing the periodic adjustment comprises synchronizing, by the first device, the first clock and the second clock of the first device.

In some embodiments, the first device is a head wearable display and the second device is a computing device that generates image data for display by the head wearable display. In some embodiments, the second device is a head wearable display and the first device is a computing device that generates image data for display by the head wearable display.

Various embodiments disclosed herein are related to a first device for wireless communication. In some embodiments, the first device includes a wireless interface to wirelessly communicate with a second device. In some embodiments, the first device includes one or more processors. In some embodiments, the one or more processors are configured to cause the wireless interface to enter a wake up state to wirelessly communicate with a second device for a service period with a determined duration scheduled according to a target wake time (TWT) protocol. In some embodiments, the one or more processors are configured to cause the wireless interface to monitor for one or more indicators from the second device indicating that additional data is available for communication. In some embodiments, the one or more processors are configured to extend the service period beyond the determined duration, in response to receiving a first indicator of the one or more indicators. In some embodiments, the one or more processors are configured to cause the wireless interface to communicate with the second device the additional data during the service period extended beyond the determined duration.

In some embodiments, the one or more processors are configured to cause the wireless interface to enter, after the service period extended beyond the determined duration, a sleep state until a start time of another service period subsequent to the service period. In some embodiments, the one or more processors are configured to cause the wireless interface to receive a second indicator of the one or more indicators, after extending the service period. In some embodiments, the one or more processors are configured to determine, in response to the second indicator, that further extending the service period responsive to the second indicator would exceed a maximum time duration for the service period. In some embodiments, the one or more processors are configured to bypass the further extending of the service period, in response to the determination.

In some embodiments, the one or more processors are configured to determine, in response to receiving the first indicator, that further extending the service period responsive to the first indicator would not exceed a maximum time duration for the service period. In some embodiments, the one or more processors are configured to further extend the service period, in response to the determination.

In some embodiments, the first indicator is an end of service period (ESOP) bit, a buffer status report (BSR) bit, or a more data field value. In some embodiments, the one or more processors are configured to perform a periodic adjustment of one or more parameters, the one or more parameters including at least one of a start time of a first service period, a duration of the first service period, or a duration between the start time of the first service period and a start time of a second service period subsequent to the first service period. In some embodiments, a frequency of the periodic adjustment is based on a difference between i) a resolution of a first clock of the one or more processors, and ii) a resolution of a second clock of the wireless interface. In some embodiments, the one or more processors are configured to synchronize, for each periodic adjustment, the first clock and the second clock of the first device.

In some embodiments, the first device is a head wearable display and the second device is a computing device that generates image data for display by the head wearable display. In some embodiments, the second device is a head wearable display and the first device is a computing device that generates image data for display by the head wearable display.

Various embodiments disclosed herein are related to a non-transitory computer readable medium storing instructions for wireless communication. In some embodiments, the instructions when executed by one or more processors, cause a wireless interface to enter a wake up state to wirelessly communicate with a separate device for a service period with a determined duration scheduled according to a target wake time (TWT) protocol. In some embodiments, the instructions when executed by the one or more processors, cause the wireless interface to monitor for one or more indicators from the separate device indicating that additional data is available for communication. In some embodiments, the instructions when executed by the one or more processors, extend the service period beyond the determined duration, in response to receiving a first indicator of the one or more indicators. In some embodiments, the instructions when executed by the one or more processors, cause the wireless interface to communicate with the separate device, the additional data during the service period extended beyond the determined duration.

Various embodiments disclosed herein are related to a method of for adjusting wireless communication between a first device and a second device. In some embodiments, the first device enters a wake up state to wirelessly communicate with a second device for a service period with a determined duration scheduled according to a target wake time (TWT) protocol. In some embodiments, the first device monitors for one or more indicators from the second device indicating that additional data is available for communication. In some embodiments, the first device determines that a last packet is transmitted to the second device for the service period. In some embodiments, the first device determines that the second device has no additional data left to transmit for the service period, according to the one or more indicators. In some embodiments, the first device enters a sleep state before an end of the service period, in response to determining that the last packet is transmitted to the second device for the service period and in response to determining that the second device has no additional data left to transmit for the service period.

DETAILED DESCRIPTION

Disclosed herein are related to systems and methods for remotely rendering an artificial reality space (e.g., an AR space, a VR space, or a MR space) by adaptively allocating resources or time slots for communication of data based on utilization and priorities of channel access.

In one configuration, two or more devices may communicate with each other pursuant to a target wake time (TWT) protocol. For example, within a service period interval, two or more devices may alternate operating in a wake up state during a service period (SP) duration and in a sleep state during a sleep duration. In the wake up state, two or more devices may communicate with each other, for example, through a wireless link. In the sleep state, two or more devices may disable communication to reduce power consumption. The SP duration and the sleep duration may be scheduled or predetermined according to an estimated traffic amount or pattern.

In some embodiments, a wake time and a sleep time for wireless communication between two or more devices can be dynamically adjusted to allow communication with reduced latency and low power consumption. For example, one or more indicators conforming to TWT protocol such as end of service period (ESOP) bits, buffer status report (BSR) bits, or more data field values can be utilized to adjust a SP duration. In one aspect, one or more indicators may be utilized to dynamically extend or reduce the scheduled SP duration, depending on an amount of data to be communicated. For example, the SP duration can be shortened or reduced when one or more indicators indicate that no additional data is left to communicate (or that a last packet is being transmitted) for the SP Duration. For example, the SP duration can be extended when one or more indicators indicate that additional data exists (or that a last packet is not being transmitted) for the SP duration. By extending the SP duration, the additional data can be exchanged or communicated without having to wait for the next SP duration to achieve latency reduction.

In one aspect, the SP duration can be adjusted after a number of service period intervals to synchronize clocks. The service period interval may correspond to a frame time (e.g., 16.6666 ms) for presenting images, e.g., images for artificial reality. In one aspect, the number of service period intervals may be determined according to a difference in resolutions of two clocks. For example, a device includes one or more processors for processing and rendering an image, and a wireless interface for wireless communication. The one or more processors may operate synchronized to a first clock and the wireless interface may operate synchronized to a second clock, where the first clock and the second clock have different resolutions. For example, the first clock can be configured in the increment of 0.6666 ms, where the second clock can be configured in the increment of 1 μs. The difference in resolutions of two clocks may create an offset in operation of the one or more processors and the wireless interface, and such difference may accumulate over time to cause power inefficiency or lower data throughput. In one aspect, the SP duration can be periodically adjusted or shifted for a number of service period intervals to correct the offset between two clocks within a single device. The number of service period intervals may be an integer number that is a multiple of a difference between the configurable increment of the first clock and the configurable increment of the second clock.

FIG.1is a block diagram of an example artificial reality system environment100. In some embodiments, the artificial reality system environment100includes an access point (AP)105, one or more HWDs150(e.g., HWD150A,150B), and one or more computing devices110(computing devices110A,110B) providing data for artificial reality to the one or more HWDs150. The access point105may be a router or any network device allowing one or more computing devices110and/or one or more HWDs150to access a network (e.g., the Internet). The access point105may be replaced by any communication device (cell site). A computing device110may be a computing device or a mobile device that can retrieve content from the access point105, and can provide image data of artificial reality to a corresponding HWD150. Each HWD150may present the image of the artificial reality to a user according to the image data. In some embodiments, the artificial reality system environment100includes more, fewer, or different components than shown inFIG.1. In some embodiments, the computing devices110A,110B communicate with the access point105through wireless links102A,102B (e.g., interlinks), respectively. In some embodiments, the computing device110A communicates with the HWD150A through a wireless link125A (e.g., intralink), and the computing device110B communicates with the HWD150B through a wireless link125B (e.g., intralink). In some embodiments, functionality of one or more components of the artificial reality system environment100can be distributed among the components in a different manner than is described here. For example, some of the functionality of the computing device110may be performed by the HWD150. For example, some of the functionality of the HWD150may be performed by the computing device110.

In some embodiments, the HWD150is an electronic component that can be worn by a user and can present or provide an artificial reality experience to the user. The HWD150may be referred to as, include, or be part of a head mounted display (HMD), head mounted device (HMD), head wearable device (HWD), head worn display (HWD) or head worn device (HWD). The HWD150may render one or more images, video, audio, or some combination thereof to provide the artificial reality experience to the user. In some embodiments, audio is presented via an external device (e.g., speakers and/or headphones) that receives audio information from the HWD150, the computing device110, or both, and presents audio based on the audio information. In some embodiments, the HWD150includes sensors155, a wireless interface165, a processor170, and a display175. These components may operate together to detect a location of the HWD150and a gaze direction of the user wearing the HWD150, and render an image of a view within the artificial reality corresponding to the detected location and/or orientation of the HWD150. In other embodiments, the HWD150includes more, fewer, or different components than shown inFIG.1.

In some embodiments, the sensors155include electronic components or a combination of electronic components and software components that detects a location and an orientation of the HWD150. Examples of the sensors155can include: one or more imaging sensors, one or more accelerometers, one or more gyroscopes, one or more magnetometers, or another suitable type of sensor that detects motion and/or location. For example, one or more accelerometers can measure translational movement (e.g., forward/back, up/down, left/right) and one or more gyroscopes can measure rotational movement (e.g., pitch, yaw, roll). In some embodiments, the sensors155detect the translational movement and the rotational movement, and determine an orientation and location of the HWD150. In one aspect, the sensors155can detect the translational movement and the rotational movement with respect to a previous orientation and location of the HWD150, and determine a new orientation and/or location of the HWD150by accumulating or integrating the detected translational movement and/or the rotational movement. Assuming for an example that the HWD150is oriented in a direction 25 degrees from a reference direction, in response to detecting that the HWD150has rotated 20 degrees, the sensors155may determine that the HWD150now faces or is oriented in a direction 45 degrees from the reference direction. Assuming for another example that the HWD150was located two feet away from a reference point in a first direction, in response to detecting that the HWD150has moved three feet in a second direction, the sensors155may determine that the HWD150is now located at a vector multiplication of the two feet in the first direction and the three feet in the second direction.

In some embodiments, the wireless interface165includes an electronic component or a combination of an electronic component and a software component that communicates with the computing device110. In some embodiments, the wireless interface165includes or is embodied as a transceiver for transmitting and receiving data through a wireless medium. The wireless interface165may operate according to or in synchronous to a clock CLK1′. The wireless interface165may communicate with a wireless interface115of a corresponding computing device110through a wireless link125(e.g., intralink). The wireless interface165may also communicate with the access point105through a wireless link (e.g., interlink). Examples of the wireless link125include a near field communication link, Wi-Fi direct, Bluetooth, or any wireless communication link. Through the wireless link125, the wireless interface165may transmit to the computing device110data indicating the determined location and/or orientation of the HWD150, the determined gaze direction of the user, and/or hand tracking measurement. Moreover, through the wireless link125, the wireless interface165may receive from the computing device110image data indicating or corresponding to an image to be rendered.

In some embodiments, the processor170includes an electronic component or a combination of an electronic component and a software component that generates one or more images for display, for example, according to a change in view of the space of the artificial reality. In some embodiments, the processor170is implemented as one or more graphical processing units (GPUs), one or more central processing unit (CPUs), or a combination of them that can execute instructions to perform various functions described herein. The processor170may operate according to or in synchronous to a clock CLK2′. The processor170may receive, through the wireless interface165, image data describing an image of artificial reality to be rendered, and render the image through the display175. In some embodiments, the image data from the computing device110may be encoded, and the processor170may decode the image data to render the image. In some embodiments, the processor170receives, from the computing device110through the wireless interface165, object information indicating virtual objects in the artificial reality space and/or depth information indicating depth (or distances from the HWD150) of the virtual objects. In one aspect, according to the image of the artificial reality, object information, depth information from the computing device110, and/or updated sensor measurements from the sensors155, the processor170may perform shading, reprojection, and/or blending to update the image of the artificial reality to correspond to the updated location and/or orientation of the HWD150.

In some embodiments, the display175is an electronic component that displays an image. The display175may, for example, be a liquid crystal display or an organic light emitting diode display. The display175may be a transparent display that allows the user to see through. In some embodiments, when the HWD150is worn by a user, the display175is located proximate (e.g., less than 3 inches) to the user's eyes. In one aspect, the display175emits or projects light towards the user's eyes according to image generated by the processor170. The HWD150may include a lens that allows the user to see the display175in a close proximity.

In some embodiments, the processor170performs compensation to compensate for any distortions or aberrations. In one aspect, the lens introduces optical aberrations such as a chromatic aberration, a pin-cushion distortion, barrel distortion, etc. The processor170may determine a compensation (e.g., predistortion) to apply to the image to be rendered to compensate for the distortions caused by the lens, and apply the determined compensation to the image from the processor170. The processor170may provide the predistorted image to the display175.

In some embodiments, the computing device110is an electronic component or a combination of an electronic component and a software component that provides content to be rendered to the HWD150. The computing device110may be embodied as a mobile device (e.g., smart phone, tablet PC, laptop, etc.). The computing device110may operate as a soft access point. In one aspect, the computing device110includes a wireless interface115and a processor118. These components may operate together to determine a view (e.g., a FOV of the user) of the artificial reality corresponding to the location of the HWD150and the gaze direction of the user of the HWD150, and can generate image data indicating an image of the artificial reality corresponding to the determined view. The computing device110may also communicate with the access point105, and may obtain AR/VR content from the access point105, for example, through the wireless link102(e.g., interlink). The computing device110may receive sensor measurement indicating location and the gaze direction of the user of the HWD150and provide the image data to the HWD150for presentation of the artificial reality, for example, through the wireless link125(e.g., intralink). In other embodiments, the computing device110includes more, fewer, or different components than shown inFIG.1.

In some embodiments, the wireless interface115is an electronic component or a combination of an electronic component and a software component that communicates with the HWD150, the access point105, other computing device110, or any combination of them. In some embodiments, the wireless interface115includes or is embodied as a transceiver for transmitting and receiving data through a wireless medium. The wireless interface115may operate according to or in synchronous to a clock CLK1. The wireless interface115may be a counterpart component to the wireless interface165to communicate with the HWD150through a wireless link125(e.g., intralink). The wireless interface115may also include a component to communicate with the access point105through a wireless link102(e.g., interlink). Examples of wireless link102include a cellular communication link, a near field communication link, Wi-Fi, Bluetooth, 60 GHz wireless link, or any wireless communication link. The wireless interface115may also include a component to communicate with a different computing device110through a wireless link185. Examples of the wireless link185include a near field communication link, Wi-Fi direct, Bluetooth, or any wireless communication link. Through the wireless link102(e.g., interlink), the wireless interface115may obtain AR/VR content, or other content from the access point105. Through the wireless link125(e.g., intralink), the wireless interface115may receive from the HWD150data indicating the determined location and/or orientation of the HWD150, the determined gaze direction of the user, and/or the hand tracking measurement. Moreover, through the wireless link125(e.g., intralink), the wireless interface115may transmit to the HWD150image data describing an image to be rendered. Through the wireless link185, the wireless interface115may receive or transmit information indicating the wireless link125(e.g., channel, timing) between the computing device110and the HWD150. According to the information indicating the wireless link125, computing devices110may coordinate or schedule operations to avoid interference or collisions.

The processor118can include or correspond to a component that generates content to be rendered according to the location and/or orientation of the HWD150. In some embodiments, the processor118includes or is embodied as one or more central processing units, graphics processing units, image processors, or any processors for generating images of the artificial reality. The processor118may operate according to or in synchronous to a clock CLK2. In some embodiments, the processor118may incorporate the gaze direction of the user of the HWD150and a user interaction in the artificial reality to generate the content to be rendered. In one aspect, the processor118determines a view of the artificial reality according to the location and/or orientation of the HWD150. For example, the processor118maps the location of the HWD150in a physical space to a location within an artificial reality space, and determines a view of the artificial reality space along a direction corresponding to the mapped orientation from the mapped location in the artificial reality space. The processor118may generate image data describing an image of the determined view of the artificial reality space, and transmit the image data to the HWD150through the wireless interface115. The processor118may encode the image data describing the image, and can transmit the encoded data to the HWD150. In some embodiments, the processor118generates and provides the image data to the HWD150periodically (e.g., every 11 ms or 16 ms).

In some embodiments, the processors118,170may configure or cause the wireless interfaces115,165to toggle, transition, cycle or switch between a sleep state (e.g., low power or inactive state) and a wake up state (e.g., active state). In the wake up state, the processor118may enable the wireless interface115, and the processor170may enable the wireless interface165, such that the wireless interfaces115,165may exchange data. In the sleep state, the processor118may disable the wireless interface115and the processor170may disable (e.g., may implement low power or reduced operation in) the wireless interface165, such that the wireless interfaces115,165may not consume power, or may reduce power consumption. The processors118,170may schedule the wireless interfaces115,165to switch between the sleep state and the wake up state periodically every frame time (e.g., 11 ms or 16 ms). For example, the wireless interfaces115,165may operate in the wake up state for 2 ms of the frame time, and the wireless interfaces115,165may operate in the sleep state for the remainder (e.g., 9 ms) of the frame time. By disabling the wireless interfaces115,165in the sleep state, power consumption of the computing device110and the HWD150can be reduced or minimized.

In some embodiments, the processors118,170may configure or cause the wireless interfaces115,165to resume communication based on stored information indicating (e.g., to use for coordinating) communication between the computing device110and the HWD150. In the wake up state, the processors118,170may generate and store information (e.g., channel, timing) of the communication between the computing device110and the HWD150. The processors118,170may schedule the wireless interfaces115,165to enter a subsequent wake up state according to timing of the previous communication indicated by the stored information. For example, the wireless interfaces115,165may predict/determine when to enter the subsequent wake up state, according to timing of the previous wake up state, and can schedule to enter the subsequent wake up state at the predicted time. After generating and storing the information and scheduling the subsequent wake up state, the processors118,170may configure or cause the wireless interfaces115,165to enter the sleep state. When entering the wake up state, the processors118,170may cause or configure the wireless interfaces115,165to resume communication via the channel or frequency band of the previous communication indicated by the stored information. Accordingly, the wireless interfaces115,165entering the wake up state from the sleep state may resume communication, while bypassing a scan procedure to search for available channels and/or performing handshake or authentication. Bypassing the scan procedure allows extension of a duration of the wireless interfaces115,165operating in the sleep state, such that the computing device110and the HWD150can reduce power consumption.

In some embodiments, the computing devices110A,110B may coordinate operations to reduce collisions or interferences. In one approach, the computing device110A may transmit a beacon frame periodically to announce/advertise a presence of a wireless link125A between the computing device110A and the HWD150A and can coordinate the communication between the computing device110A and the HWD150A. The computing device110B may monitor for or receive the beacon frame from the computing device110A, and can schedule communication with the HWD150B (e.g., using information in the beacon frame, such as an offset value) to avoid collision or interference with communication between the computing device110A and the HWD150A. For example, the computing device110B may schedule the computing device110B and the HWD150B to enter a wake up state, when the computing device110A and the HWD150A operate in the sleep state. For example, the computing device110B may schedule the computing device110B and the HWD150B to enter a sleep mode/state, when the computing device110A and the HWD150A operate in the wake up state. Accordingly, multiple computing devices110and HWDs150in proximity (e.g., within 20 ft) may coexist and operate with reduced interference.

FIG.2is a diagram of a HWD150, in accordance with an example embodiment. In some embodiments, the HWD150includes a front rigid body205and a band210. The front rigid body205includes the electronic display175(not shown inFIG.2), lens (not shown inFIG.2), the sensors155, the wireless interface165, and the processor170. In the embodiment shown byFIG.2, the wireless interface165, the processor170, and the sensors155are located within the front rigid body205, and may not be visible to the user. In other embodiments, the HWD150has a different configuration than shown inFIG.2. For example, the wireless interface165, the processor170, and/or the sensors155may be in different locations than shown inFIG.2.

Various operations described herein can be implemented on computer systems.FIG.3shows a block diagram of a representative computing system314usable to implement the present disclosure, in accordance with an example embodiment. In some embodiments, the AP105, the console110, the HWD150or any combination of them ofFIG.1are implemented by the computing system314. Computing system314can be implemented, for example, as a consumer device such as a smartphone, other mobile phone, tablet computer, wearable computing device (e.g., smart watch, eyeglasses, head wearable display), desktop computer, laptop computer, or implemented with distributed computing devices. The computing system314can be implemented to provide VR, AR, MR experience. In some embodiments, the computing system314can include conventional computer components such as processors316, storage device318, network interface320, user input device322, and user output device324.

Network interface320can provide a connection to a wide area network (e.g., the Internet) to which WAN interface of a remote server system is also connected. Network interface320can include a wired interface (e.g., Ethernet) and/or a wireless interface implementing various RF data communication standards such as Wi-Fi, Bluetooth, or cellular data network standards (e.g., 3G, 4G, 5G, 60 GHz, LTE, etc.).

User input device322can include any device (or devices) via which a user can provide signals to computing system314; computing system314can interpret the signals as indicative of particular user requests for information. User input device322can include any or all of a keyboard, touch pad, touch screen, mouse or other pointing device, scroll wheel, click wheel, dial, button, switch, keypad, microphone, sensors (e.g., a motion sensor, an eye tracking sensor, etc.), and so on.

User output device324can include any device via which computing system314can provide information to a user. For example, user output device324can include a display to display images generated by or delivered to computing system314. The display can incorporate various image generation technologies, e.g., a liquid crystal display (LCD), light-emitting diode (LED) including organic light-emitting diodes (OLED), projection system, cathode ray tube (CRT), or the like, together with supporting electronics (e.g., digital-to-analog or analog-to-digital converters, signal processors, or the like). A device such as a touchscreen that function as both input and output device can be used. Output devices324can be provided in addition to or instead of a display. Examples include indicator lights, speakers, tactile “display” devices, printers, and so on.

FIG.4is a timing diagram400showing a wake-up/sleep schedule of a computing device110and a HWD150utilizing Target Wake Time (TWT), according to an example implementation of the present disclosure. TWT is a time agreed upon by a computing device110and the HWD150, or specified/configured by another device (e.g., the access point105). A TWT may be characterized by a periodic, fixed, wake-sleep schedule. The computing device110and the HWD150can wake up periodically (e.g., at a fixed, configured time interval/period/cycle) based on the TWT.

The interval of time between TWT start time402and the subsequent TWT start time402′ is the SP interval410. The SP interval410may correspond to a frame time (e.g., 16.6666 ms) for presenting artificial reality. Within the SP interval410, the computing device110and the HWD150may alternate (or transition from) operating in a wake up state during a SP duration404and in a sleep state during a sleep duration406.

In some embodiments, the computing device110and the HWD150may enter the wake up state at TWT start time402. The computing device110and the HWD150may operate in the wake up state for the SP duration404. In the wake up state, the computing device110and the HWD150may enable the processors (e.g., processors118,170) and the wireless interfaces (e.g., wireless interfaces115,165), and transmit and/or receive data, for example, for presenting artificial reality.

In some embodiments, at the end of the SP duration404, the computing device110and the HWD150may enter a sleep state. The computing device110and the HWD150may operate in the sleep state during the sleep duration406, until a subsequent TWT start time402′. In the sleep state, the computing device110and the HWD150may disable or power off the processors (e.g., processors118,170) and the wireless interfaces (e.g., wireless interfaces115,165) to achieve power savings.

In some embodiments, the TWT start time402,402′ may be used to synchronize clocks within a device. For example, a video clock CLK2(e.g., clock for timing, generating and/or processing video frames) may not be aligned with a wireless clock CLK1(e.g., clock for timing/scheduling/processing transmissions and/or reception of wireless messages) within a device. Methods may be used to align the wireless clocks CLK1, CLK1′ and the video clocks CLK2, CLK2′ in the computing device110and HWD150. In one approach, the computing device110and the HWD150may synchronize wireless clocks CLK1, CLK1′ of the wireless interfaces115,165when communicating with each other. However, clock misalignment may be present within a single device, between a wireless clock CLK1and a video clock CLK2, due to clock drift between the individual clock crystals over time. For example, the computing device110may have to wait to transmit video packets if the video clock CLK2of the processor118lags behind the wireless clock CLK1of the wireless interface115. The time wasted waiting for the preparation of packets due to misaligned clocks may cause increased latency and/or waste power resources by unnecessarily extending wake-up time for WiFi operation (e.g., in the wireless module/circuitry/chip). Similarly, the computing device110may wake-up and prepare video packets, but not be able to transmit the video packets if the wireless clock CLK1of the wireless interface115lags behind the video clock CLK2of the processor118. The misalignment of the clocks CLK1, CLK2may be worsened by resolution differences between the clocks. For example, the video clock CLK2of the processor118may be configured in the increment of milliseconds, but the wireless clock CLK1of the wireless interface115may be configured in the increment of microseconds. For instance, a 60 Hz video frame may start every 16.66 ms, whereas a TWT SP interval may be set or configured to integer number of microseconds. Accordingly, the clocks CLK1, CLK2may be offset by the remainder of 0.66 ms which is added/accumulated for each/every video frame. As such, the clock drift may worsen over time.

In some embodiments, a field in the TWT protocol (for example, a field in the TWT Information frame) may be established/configured/modified/repurposed to include a shift/adjustment to the start time of the next SP duration404to counter the effect of the clock misalignment. For example and in some embodiments, the “Next Wake Up” time field, indicating the start time402′ of the next SP duration404, may be periodically adjusted to address/correct clock misalignment. Every N video frames (or at some other interval or event trigger), the wake-up time of the computing device110and/or the HWD150may be shifted/adjusted. N may be a number configured based on the video frame rate because the clock drift and clock offset can depend on the video frame rate. For example, N may be an integer number that is a multiple of a difference between the configurable increment of the video clock CLK2and the configurable increment of the wireless clock CLK1. In some embodiments, the parameters of the TWT may be negotiated and/or updated in management frames such as the TWT request frame and a TWT response frame. The TWT may be paused and/or resumed at the beginning of a TWT start time via a TWT Information Frame (sometimes referred to as TWT Info frame) and an ACK frame.

Streams of traffic across a network may be characterized by different types of traffic. For instance, an application may be characterized by latency sensitive data (e.g., video/voice (VINO), real time interactive applications, and the like) or other data (e.g., best effort/background applications (BE/BK)). Latency sensitive data may be identifiable by its characteristic of periodic bursts of traffic. For instance, video display traffic may be driven by the refresh rate 60 Hz, 72 Hz, 90 Hz, and 120 Hz. An application and/or device may have combinations of traffic types. Further, each stream of traffic associated with the application and/or device may be more or less spontaneous and/or aperiodic than the other streams of traffic associated with the application and/or device. Thus, traffic may vary according to applications and/or channel rate dynamics.

For example, the duration of traffic to be transmitted may depend on the transmission rate, which may depend on various algorithms adapting to channel conditions. Further, the traffic duration may depend on the occupancy of the wireless medium. For instance, computing devices implementing contention based medium access protocols may wait a duration of time before being able to contend to transmit traffic using the medium. Additionally or alternatively, the amount of traffic to be transmitted may be aperiodic, bursty, and the like. For example, a video that has been compressed may occupy one or more frames of different sizes. That is, the compressed video frame size may not be constant.

As discussed herein, the TWT can be a negotiated and agreed upon time. Further, both traffic transmissions and traffic durations are variable in nature. As such, the SP duration404may be longer than a time duration for the computing device110to transmit content or data (e.g., image data for AR/VR) of the computing device110. Accordingly, the computing device110may be awake for longer than the time needed to transmit traffic, resulting in the computing device110inefficiently consuming power. Additionally or alternatively, the SP duration404may be shorter than a time duration for the computing device110to transmit content or data (e.g., image data for AR/VR). Accordingly, the computing device110may be caused to wait until the subsequent SP duration404to transmit packets. Waiting for the subsequent SP duration404may add unnecessary latency and/or packet loss. The TWT may be improved by adaptively waking up and entering a sleep state based on traffic conditions/characteristics/types. The traffic-adaptive mechanism can allow the computing device110, HWD150, access point105, or any combination of them to enter sleep and/or wake up state(s) based on the traffic needs/conditions/characteristics/types, improving the tradeoff between power consumption and low latency transmissions.

FIG.5is a flowchart showing a process500of improving power consumption in a computing device110while communicating latency sensitive data using TWT, according to an example implementation of the present disclosure. In some embodiments, the process500is performed by the computing device110. In some embodiments, the process500is performed by other entities (e.g., access point105or HWD150). In some embodiments, the process500includes more, fewer, or different steps than shown inFIG.5.

In step502, the computing device110may execute or perform a TWT setup phase. The computing device110and the HWD150may agree on values for the TWT parameters, according to the negotiation process. For instance, the computing device110or HWD150may negotiate TWT parameters such as a TWT start time402, the SP duration404, and/or the SP interval410.

During the TWT setup phase in the step502, the computing device110and the HWD150may store, employ or utilize settings or configurations504. Example settings or configurations504include default schedule505, packet header507, and max timing parameter509. In one approach, the computing device110and the HWD150may operate according to the default schedule505including predetermined schedules for TWT start time402, SP duration404, SP interval410, etc.

In one approach, the computing device110and HWD150may dynamically adjust a TWT start time402, the SP duration404, and/or the SP interval410by analyzing a packet header507. For example, TWT may be adaptive based on the condition(s)/characteristic(s)/type(s) of traffic being transmitted and/or received. The computing device110and/or HWD150may analyze one or more bits (or indicators) of a packet header of a traffic packet that is received/transmitted to dynamically adjust TWT.

In one example, the computing device110and/or HWD150may use an end of service period (ESOP) bit515in the packet header507to transmit/convey/indicate traffic information. The ESOP bit515may be used to indicate whether more traffic is to be transmitted and/or received between the computing device110and the HWD150. For instance, the ESOP bit515in the packet header507may be set to ‘0’, indicating that more traffic is to be transmitted by the computing device110and/or HWD150(or that the last packet is not being transmitted yet). The computing device110and/or HWD150may set the ESOP bit515in the packet header to ‘1’ to indicate that a last packet is being transmitted. That is, the ESOP bit515may indicate, or be used to determine when the computing device110and/or HWD150has finished/completed transmission in the current service period.

In one example, the computing device110and the HWD150may use a buffer status report (BSR) field517in a packet header to indicate whether there is more traffic to be transmitted. For instance, one or more bits in the BSR field517in the packet header507may be set to ‘0’, indicating that more traffic is to be transmitted by the computing device110and/or HWD150. The computing device110and/or HWD150may set one or more bits in the BSR field517in the packet header to ‘1’ to indicate that a last packet is being transmitted. The BSR field517may be found in packet headers configured for IEEE 802.11ax/ay communication protocol.

In one example, the computing device110and the HWD150may use one or more bits in a packet header507(e.g., the “more data” field519in a packet header507) associated with an acknowledgement frame, data frame, management frame and the like, to indicate whether more traffic is to be transmitted. For instance, one or more bits in the packet header507may be set to ‘0’, indicating that more traffic is to be transmitted by the computing device110and/or HWD150. The computing device110and/or HWD150may set one or more bits in the packet header507to ‘1’ to indicate that a last packet is to be transmitted.

In one example, a maximum time/timing/duration parameter509(sometimes referred as max parameter) for the SP duration404may be set and utilized to ensure power savings and ensure fairness of channel access. The max parameter for the SP duration404may be a parameter such as a timing or timer parameter. As discussed above, the SP duration404may be extended to allow communication of data to obviate waiting for the next SP duration404and achieve latency reduction. Independent of the extension of the SP duration404, the computing device110and/or the HWD150may keep track of the time duration of the computing device110and/or the HWD150has remained in the wake up state for communication. If the time duration reaches the maximum time as indicated by the max parameter509, the computing device110and/or the HWD150may enter the sleep state to ensure a sufficient sleep duration and allow other devices to share or access the communication channel. That is, the max parameter509may prevent the computing device110and the HWD150from continuously remaining in wake-up state. In one approach, when a first device (e.g., computing device110) determines that the first device has operated or remained in the wake up state for the maximum time as indicated by the max parameter509, the first device may transmit one or more indicators to notify a second device (e.g., HWD150) that the first device is entering the sleep state. In response to the one or more indicators, the second device may enter the sleep state. The first device may enter the sleep state after transmitting the one or more indicators.

In step506, in the event the conditions for the sleep state have been satisfied, the computing device110and/or HWD150may enter the sleep state. The conditions for entering into the sleep state may include reaching the default time to enter the sleep state (e.g., the scheduled end of the SP duration404), operating in the wake-up state for the maximum time as indicated by the maximum timing parameter509of the SP duration, and/or receiving an end of traffic indication (e.g., an ‘1’ indicated by the ESOP bit515in a packet header).

The HWD150and the computing device110may wait for the transmission and reception of an end of traffic indication before entering a sleep state to minimize the possibility, for instance, of the computing device110entering a sleep state while the HWD150still is to send traffic or is in the process of sending traffic to the computing device110. That is, the HWD150and the computing device110may both receive indications that they each have respectively finished transmitting traffic. In some embodiments, a first device (e.g., computing device110or HWD150) may receive a first end of traffic indication (e.g., ESOP bit=1) from the second device, and may send a second end of traffic indication (e.g., ESOP bit=1) to the second device, before the first device may enter sleep state/mode.

FIG.6is a flowchart showing a process600of adaptively adjusting a service period duration404, according to an example implementation of the present disclosure. In some embodiments, the process600is performed by the computing device110. In some embodiments, the process600is performed by other entities (e.g., access point105or HWD150). In some embodiments, the process600includes more, fewer, or different steps than shown inFIG.6.

In one approach, the computing device110enters610a wake up state at the TWT start time402. During the SP duration404, the computing device110may operate in the wake up state to enable the processor118and the wireless interface115. The SP duration404, the SP interval410, and/or the TWT start time402may be predetermined. One or more of the SP duration404, the SP interval410, and/or the TWT start time402may be dynamically negotiated or adjusted according to traffic or channel condition. When the computing device110operates in the wake up state during the SP duration404, the HWD150may also operate in the wake up state.

In one approach, the computing device110operating in the wake up state during the SP duration404communicates620data, for example, with the HWD150. In one example, the HWD150generates sensor measurement data indicating a location and/or an orientation of the HWD150, and transmits the sensor measurement data to the computing device110during the SP duration404. The computing device110may receive the sensor measurement data, and generate image data corresponding to a view of artificial reality space corresponding to the location and/or the orientation of the HWD150during the SP duration404. The computing device110may transmit the image data to the HWD150during the SP duration404. Based on the image data, the HWD150may render an image of the view of artificial reality space.

In some embodiments, the computing device110or the HWD150may include one or more indicators (e.g., ESOP bit515, buffer status report517, more data fields519, etc.) to notify whether additional data (or more data) exists for transmission by the computing device110. For example, ESOP bit515may be set to ‘1’ to indicate that a last packet is being transmitted or no more additional data exists for transmission for the SP duration404. For example, ESOP bit515may be set to ‘0’ to indicate that the last packet is not being transmitted or more additional data exists for transmission by the computing device110for the SP duration404.

In one approach, the computing device110determines630whether additional data to communicate exists. The computing device110may determine that there is no additional data to transmit, if the last packet of data for the SP duration404is transmitted to the HWD150. Similarly, the computing device110may determine that there is no additional data left to receive, if the computing device110receives one or more bits indicating that there is no additional data left for transmission by the HWD150(e.g., as indicated by ESOP of the HWD150). If there is no additional data left to transmit and receive for the remainder of the SP duration404, the computing device110may enter670the sleep state during the sleep duration406until the next TWT start time402′. During the sleep duration406, the computing device110may operate in the sleep state to disable the wireless interface115and the processor118thereby achieving power savings. The HWD150may also determine that there is no additional data left to transmit and receive for the reminder of the SP duration404in a similar manner based on one or more indicators from the computing device110, and operate in the sleep state to disable the wireless interface165and the processor170during the sleep duration406.

In one approach, if there is data left/remaining to receive or transmit, the computing device110may determine640whether an end of SP duration404has reached or not. If the end of SP duration404has not reached, the computing device110may proceed to the step620. If the end of SP duration404has reached but additional data for communication exists, the computing device110may determine650whether SP duration is extendable. For example, the computing device110may determine whether the SP duration404exceeds a maximum duration allowed, for example, as indicated by the max parameter509. If the SP duration404exceeds the maximum duration, the computing device110may determine that the SP duration404is not extendable. In response to determining that the SP duration404is not extendable, the computing device110may enter the sleep state in the step670. If the SP duration404does not exceed the maximum duration, the computing device110may determine that the SP duration404is extendable. In response to determining that the SP duration404is extendable, the computing device110may extend660the SP duration404and proceed to the step620. In one approach, the computing device110may extend the SP duration404by a predetermined time duration (e.g., 0.1 ms). Alternatively or additionally, the computing device110may determine the time duration for transmitting remaining data left to transmit/receive, and can extend the SP duration404by the determined time duration.

In some embodiments, the computing device110independently determines665whether the SP duration404has reached (or has been extended up to) the allowed maximum time as indicated by the max parameter509. If the SP duration404has not reached (or has not yet been extended up to) the allowed maximum time, the computing device110may operate without interruption. If the SP duration404has reached (or has been extended up to) the allowed maximum time, the computing device110may enter the sleep state in the step670. Entering the sleep state when the SP duration404has reached (or has been extended up to) the allowed maximum time can ensure fairness of channel access or channel sharing with other devices. In addition, entering the sleep state when the SP duration404has reached the allowed maximum time can prevent excessive power consumption by extending the SP duration404beyond the allowed maximum time.

Systems and methods described herein may be embodied in other specific forms without departing from the characteristics thereof. References to “approximately,” “about” “substantially” or other terms of degree include variations of +/−10% from the given measurement, unit, or range unless explicitly indicated otherwise. Coupled elements can be electrically, mechanically, or physically coupled with one another directly or with intervening elements. Scope of the systems and methods described herein is thus indicated by the appended claims, rather than the foregoing description, and changes that come within the meaning and range of equivalency of the claims are embraced therein.