MAC Layer Motion Data Transmission for VR Beam Tracking
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Solution Overview
Problem
Current wireless communication technologies, particularly in mmWave bands, face challenges with high latency and beam misalignment issues when used in virtual reality (VR) head-mounted displays (HMDs), leading to motion sickness due to insufficient tracking of user motion, especially in fast-moving applications.
Innovation Solution
A communication method that transmits motion information, such as rotation and orientation data from an inertial measurement unit (IMU), directly within the MAC or PHY layer of the OSI model, allowing for low-latency adjustments in beamforming and content delivery, thereby reducing motion-to-photon latency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If motion information is transmitted through upper layers (transport layer or above), then data integrity and protocol compliance are ensured, but latency increases due to additional processing steps
Solution Approach 1:
The patent segments the communication protocol stack into multiple pathways: a standard pathway for regular data (ensuring integrity through upper-layer processing) and a specialized low-latency pathway for motion information (bypassing upper layers to reach MAC/PHY directly). This segmentation allows different data types to be handled according to their specific requirements.
Solution Approach 2:
The patent introduces an intermediary mechanism at the MAC layer that receives motion information directly from the HMD device and forwards it to the server without requiring upper-layer processing. This intermediary pathway acts as a mediator that maintains data integrity through controlled access while eliminating unnecessary processing delays.
2Device complexity
If traditional wireless communication protocols are used without motion information transmission, then system complexity is reduced, but beam misalignment occurs during HMD movement
Solution Approach 1:
The patent implements preliminary action by having the HMD device continuously sense and report motion information (acceleration, rotation) to the server before actual movement occurs. The server uses this advance information to pre-adjust beamforming parameters, ensuring beam alignment is maintained proactively rather than reactively.
Solution Approach 2:
The patent establishes a feedback loop where motion sensors in the HMD continuously monitor device movement and transmit this information to the server. The server processes this feedback and dynamically adjusts transmission beams accordingly, creating a closed-loop control system that maintains reliable communication during movement.
3Measurement precision
If motion tracking is implemented using traditional methods, then basic motion detection is achieved, but motion-to-photon latency exceeds acceptable thresholds causing motion sickness
Solution Approach 1:
The patent extracts the motion information transmission pathway from the standard upper-layer protocol stack and places it directly at the MAC/PHY layer. This extraction removes unnecessary processing intermediaries while preserving the precision of motion sensing, achieving ultra-low latency motion-to-photon transmission below the 20ms threshold required to prevent motion sickness.
Data Source
AI summary
To enable fast beam tracking and/or low latency a first communication device comprising a sensing circuitry configured to sense motion of the first communication device and to generate motion information representing the sensed motion, the motion information comprising rotation information indicating rotation and/or orientation of the first communication device, and a communication circuitry configured to transmit the motion information to a second communication device within a layer of a hierarchical layer model lower than a transport layer. A second communication device comprises a communication circuitry configured to receive motion information from a first communication device within a layer of a hierarchical layer model lower than a transport layer.