HMD Beam Controller Positional Tracking Latency

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Solution Overview

Problem

Current wireless communication technologies in virtual and augmented reality systems, such as those based on the IEEE 802.11ad standard, face high overhead and latency in beam training and tracking, which limits their ability to handle typical head-mounted display movements and is prone to data losses and non-line-of-sight conditions.

Innovation Solution

The implementation of a positional tracking system in both the head-mounted display and console, allowing for 'inside-out' or 'outside-in' positional tracking to automatically adjust directional beams for optimal communication, reducing latency and overhead by determining the best beam direction based on the HMD's position relative to the console without the need for feedback.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If beam training and beam tracking are performed using sector level sweep, then beam forming effectiveness is maintained, but latency increases to 2-100 ms and overhead increases due to feedback communication

Engineering Contradiction:

Improvebeam forming effectivenessVSAvoidbeam training latency

Core Design Contradiction:

ReliabilityVSLoss of time

Solution Approach 1:

The system performs preliminary beam training to establish initial beam directions before actual data transmission. The console and HMD pre-determine beamforming parameters and directional beams in advance, so when the HMD moves, the system can quickly switch to pre-calculated alternative beams without performing time-consuming real-time beam training.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The HMD includes a beam controller that autonomously determines changes in positional information and selects appropriate directional beams based on tracked position data, without requiring continuous feedback communication with the console. This self-service capability eliminates feedback overhead and reduces latency.

Inventive Principle:

Principle #25Self-service

2Loss of time

If beam refinement protocol is used to reduce latency to 200-300 μs per iteration, then response time improves, but multiple iterations are needed and data losses occur due to imperfections

Engineering Contradiction:

Improvebeam tracking latencyVSAvoidcommunication reliability

Core Design Contradiction:

Loss of timeVSReliability

Solution Approach 1:

The system replaces iterative beam refinement protocols with a positional tracking-based beam selection mechanism. Instead of repeatedly adjusting beams based on feedback signals, the system uses positional information from tracking systems to directly determine optimal beam directions, substituting a more reliable measurement-based approach for trial-and-error beam refinement.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

3Device complexity

If digital baseband estimate variation and antenna beam pattern limitations are accepted, then system complexity is reduced, but beam direction accuracy is limited causing delay between beam switching

Engineering Contradiction:

Improvesystem complexityVSAvoidbeam direction accuracy

Core Design Contradiction:

Device complexityVSMeasurement precision

Solution Approach 1:

The system introduces positional tracking information as an intermediary to bridge the gap between limited baseband estimation capabilities and required beam direction accuracy. The tracking system provides precise positional data that compensates for inaccuracies in digital baseband estimates, enabling more accurate beam direction determination without increasing baseband processing complexity.

Inventive Principle:

Principle #24Intermediary (Mediator)

4Reliability

If conventional beam training is used, then line-of-sight communication is supported, but non-line-of-sight conditions cause data loss and prompt remedy cannot be provided

Engineering Contradiction:

Improveline-of-sight communication reliabilityVSAvoidnon-line-of-sight condition handling

Core Design Contradiction:

ReliabilityVSAdaptability or versatility

Solution Approach 1:

The system dynamically adapts beam directions based on real-time positional tracking information. When the HMD moves or environmental conditions change, the beam controller continuously updates beam directions to maintain optimal communication paths. This dynamic adaptation enables the system to respond to both line-of-sight and non-line-of-sight conditions, switching between direct and reflected path beams as needed.

Inventive Principle:

Principle #15Dynamics

Data Source

PatentUS11362703B1Positional tracking assisted beam forming in wireless virtual reality systems

Publication Date: 2022.06.14 META PLATFORMS TECHNOLOGIES LLC

AI summary

Embodiments of the present disclosure support a head-mounted display (HMD) wirelessly coupled to a console. The HMD includes a positional tracking system, a beam controller and a transceiver. The positional tracking system tracks position of the HMD and generates positional information describing the tracked position of the HMD. The transceiver communicates with a console via a wireless channel, in accordance with communication instructions, the communication instructions causing the transceiver to communicate over one directional beam of a plurality of directional beams. The beam controller determines a change in the positional information. Based on the change to the positional information, the beam controller determines a directional beam of the plurality of directional beams. The beam controller further generates the communication instructions identifying the determined directional beam, and provides the communication instructions to the transceiver.