Split Rendering Synchronization for AR Latency and Power
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Solution Overview
Problem
In split rendering applications for augmented and virtual reality, there is a need to optimize graphics processing to reduce power consumption and thermal issues in wireless devices like AR glasses, while maintaining low latency and high visual quality, as current methods often result in higher latency and visual quality issues due to unsynchronized uplink and downlink data transmissions.
Innovation Solution
Implementing a target wake time (TWT) synchronization technique that aligns uplink and downlink data transmissions with a fixed service period, allowing the modem to switch on and off at a defined cadence, and utilizing timing synchronization functions to reduce power consumption and thermal issues, while ensuring synchronized vertical synchronization and decode times to improve visual quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If unsynchronized uplink and downlink data transmissions are used, then device complexity is reduced, but latency increases and visual quality deteriorates
Solution Approach 1:
The patent implements Target Wake Time (TWT) synchronization that establishes periodic service periods for uplink and downlink transmissions. The modem switches on and off at defined cadences aligned with these periodic service periods, creating synchronized transmission windows that reduce latency while maintaining manageable complexity through regular intervals.
Solution Approach 2:
The system uses feedback mechanisms where the server calculates latency associated with receiving uplink data (such as head pose information) and transmits this latency feedback to the client device. The client device then adjusts its transmission schedule based on this feedback, creating a closed-loop control system that optimizes synchronization and reduces latency.
2Loss of time
If continuous modem operation is used, then transmission latency is reduced, but power consumption and thermal issues increase
Solution Approach 1:
The TWT synchronization establishes periodic service periods where the modem operates only during defined windows rather than continuously. The modem switches on at the beginning of service periods to handle synchronized uplink and downlink transmissions, then switches off during idle periods, reducing power consumption while maintaining low latency through predictable periodic operation.
Solution Approach 2:
The system performs preliminary calculation of TWT parameters including service period start times and durations before actual transmission begins. This preliminary setup allows the modem to be activated only when needed for synchronized transmissions, avoiding continuous operation and reducing power consumption while maintaining readiness for low-latency communication.
3Use of energy by moving object
If synchronized TWT parameters are implemented, then power consumption is reduced, but transmission schedule complexity increases
Solution Approach 1:
The server calculates latency feedback based on received uplink data and transmits this information to the client device. The client device uses this feedback to adjust its transmission schedule within the TWT framework, allowing dynamic optimization of the transmission schedule based on actual conditions rather than requiring complex pre-planning of all schedule parameters.
Solution Approach 2:
The system dynamically adjusts TWT parameters such as service period start times and durations based on calculated latency and transmission requirements. Rather than using a fixed rigid schedule, the parameters are modified to optimize both power consumption and transmission efficiency, reducing the need for overly complex schedule management.
4Adaptability or versatility
If asynchronous frame decoding is used, then processing flexibility is improved, but visual quality deteriorates due to unsynchronized display timing
Solution Approach 1:
The TWT synchronization aligns frame decoding and display operations with periodic service periods. Frames are decoded and displayed at synchronized intervals that match the periodic transmission schedule, ensuring that visual output is synchronized with incoming data while still allowing flexible processing within each service period window.
Data Source
AI summary
Aspects presented herein relate to methods and devices for graphics processing including an apparatus, e.g., client device or a server. The apparatus may transmit, to a server at a beginning of a first time period, at least one first head pose associated with a position of the client device, the first time period being synchronized with the server. The apparatus may also receive, from the server during a second time period, at least one first frame including first content based on the at least one first head pose, the second time period being synchronized with the server. Further, the apparatus may display, upon receiving the at least one frame during the second time period, the at least one first frame including the first content.