GPS Time-Aiding via Bluetooth Clock Synchronization
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Solution Overview
Problem
Current GPS receivers on mobile devices, especially small wearable devices, require significant time and computational resources to calculate a position solution, particularly during a cold start, due to limited antenna performance and signal strength.
Innovation Solution
The system employs time-aiding techniques, including synthetic ephemeris aiding and Bluetooth-based clock synchronization, to reduce the time and computational resources needed for GPS positioning, providing up to an 11 dB gain in signal strength and faster fix times by aligning Bluetooth and LTE clocks and using Unicast Directionless Data for precise timing adjustments.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If GPS receiver performs cold start calculation without aiding data, then position solution can be calculated autonomously, but time required and computational resources increase significantly
Solution Approach 1:
The system performs preliminary actions by obtaining ephemeris data and time information from external sources (mobile device, synthetic generation) before the GPS receiver needs to calculate position. This pre-prepared aiding data is stored and readily available when the receiver wakes up, eliminating the need for time-consuming autonomous acquisition during cold start.
Solution Approach 2:
The patent introduces intermediary components including a memory device storing ephemeris data, a processor for generating synthetic ephemeris, and a time-aiding interface receiving time information from mobile devices. These intermediaries provide pre-processed aiding data to the GPS receiver, reducing its computational burden and acquisition time.
2Loss of time
If GPS receiver uses synthetic ephemeris aiding, then time to first fix is reduced, but signal strength requirements increase
Solution Approach 1:
The system changes parameters by providing synthetic ephemeris data with predetermined accuracy levels and time-aiding information with specific precision. By controlling the quality and precision of aiding data parameters, the system optimizes the balance between reduced time to first fix and maintained signal strength thresholds suitable for wearable device antennas.
3Volume of moving object
If wearable device uses smaller antenna to reduce device size, then device portability improves, but GPS signal reception capability deteriorates
Solution Approach 1:
The system pre-obtains and stores ephemeris data and time information before GPS signal acquisition. This preliminary preparation compensates for the limited signal reception capability of small antennas by reducing the time and computational resources needed for position calculation, allowing reliable GPS functionality despite antenna size constraints.
Data Source
AI summary
A system and method for time-aiding an autonomous Global Positioning System device over a Bluetooth connection allows for a faster time to fix by allowing faster acquisition of time and ephemeris data. The time-aiding information may be distributed in a one-to-one manner or in a manner that allows for the synchronization of multiple devices.