Dynamic Signal Quality Indicator for GNSS Battery Saving
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Solution Overview
Problem
User devices, such as smartphones, face high battery drain due to frequent refresh rates of navigation messages required for accurate positioning, which increases CPU load and power consumption, especially in Global Navigation Satellite Systems (GNSS) like GPS and Galileo, where constant Signal Quality Indicators (SQI) do not account for time-evolving ranging errors.
Innovation Solution
Implementing a dynamic Signal Quality Indicator (SQI) that evolves over time, allowing user devices to determine the maximum tolerable ranging error based on current Dilution of Precision (DOP) and adjust the refresh rate of navigation messages accordingly, thereby reducing processing and power consumption by ignoring message updates until necessary.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If navigation messages are frequently refreshed to maintain positioning accuracy, then positioning accuracy is improved, but battery consumption increases
Solution Approach 1:
The patent applies dynamics by making the refresh rate of navigation messages adaptive rather than fixed. The receiver adjusts the refresh rate dynamically based on the actual ranging error evolution, which varies over time. This allows the system to optimize between positioning accuracy and power consumption by refreshing messages only when necessary, rather than at constant high frequency.
Solution Approach 2:
The patent changes the parameter of refresh rate from a constant value to a time-dependent value. By using a model that predicts ranging error as a function of time, the system determines when the error exceeds acceptable thresholds and adjusts the refresh rate accordingly. This parameter change enables the receiver to maintain positioning accuracy while reducing unnecessary message refreshes that consume battery power.
2Measurement precision
If navigation messages are frequently refreshed to maintain positioning accuracy, then positioning accuracy is improved, but processing load increases
Solution Approach 1:
The patent applies dynamics by making the refresh rate of navigation messages adaptive rather than fixed. The receiver adjusts the refresh rate dynamically based on the actual ranging error evolution, which varies over time. This allows the system to optimize between positioning accuracy and power consumption by refreshing messages only when necessary, rather than at constant high frequency.
Solution Approach 2:
The patent applies partial action by performing message refreshes only to the extent necessary to maintain acceptable positioning accuracy. Instead of continuously refreshing messages at maximum frequency, the system refreshes only when the predicted ranging error exceeds acceptable thresholds, reducing unnecessary processing while maintaining sufficient positioning accuracy.
3Measurement precision
If constant SQI is used for ranging error estimation, then system complexity is reduced, but positioning accuracy degrades over time
Solution Approach 1:
The patent applies preliminary action by pre-establishing a model that describes the time evolution of ranging errors before actual positioning operations begin. This model, which can be derived from satellite ephemeris data or historical measurements, allows the receiver to predict when ranging errors will exceed acceptable thresholds without needing to constantly monitor and recompute SQI values, thus reducing real-time processing complexity while maintaining accuracy.
Solution Approach 2:
The patent substitutes the mechanical approach of constantly measuring and updating SQI values with a modeling approach that predicts ranging error evolution mathematically. Instead of continuously acquiring new measurements to update error estimates, the system uses a pre-established model to predict error behavior over time, reducing the need for continuous data acquisition and processing while maintaining positioning accuracy.
Data Source
Figure 1
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Figure 3A~3C
AI summary
A user device (UD) for performing ranging measurements is provided. The UD (100) comprises a receiving unit (120) and a processing unit (110). The receiving unit is adapted to receive a plurality of signals from a plurality of navigation satellites. Each of the plurality of signals comprises a navigation message during a first validity period. The processing unit is adapted to process the navigation message in the first validity period. The processing unit is adapted to perform ranging measurements in a second validity period based on the plurality of signals and the processed navigation message in the first validity period. The second validity period is different from the first validity period.