Navigation Device Seed Positioning via Wireless Network
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Solution Overview
Problem
Portable navigation devices (PNDs) face significant delays in obtaining a position fix, especially after being switched off and relocated over long distances, due to the time-consuming process of searching for visible GNSS satellites, which increases hardware complexity and power consumption, and existing solutions like A-GPS incur roaming costs and compatibility issues.
Innovation Solution
A navigation device that uses time zone and wireless network information to determine a seed position, allowing the GNSS receiver to quickly identify visible satellites, reducing the Time To First Fix (TTFF) without increasing power consumption and enabling implementation through software or firmware upgrades, eliminating the need for a Subscriber Identity Module (SIM) and avoiding roaming call costs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the GNSS receiver performs a full satellite search after relocation, then it can acquire all visible satellites, but the Time To First Fix (TTFF) increases significantly
Solution Approach 1:
The patent applies preliminary action by using wireless network information (cell tower triangulation) to pre-determine an approximate seed position before GNSS satellite acquisition. This preliminary positioning step allows the system to predict which satellites should be visible, thereby reducing the TTFF when the device is relocated without requiring a complete satellite search.
Solution Approach 2:
The patent uses wireless network positioning as an intermediary method to bridge the gap between device relocation and GNSS satellite acquisition. By obtaining approximate location data from cell towers first, the system can then use this intermediate position information to guide the GNSS satellite search process, reducing the time required for full satellite acquisition.
2Productivity
If the GNSS receiver increases search channels to reduce TTFF, then satellite acquisition speed improves, but hardware complexity and power consumption increase
Solution Approach 1:
The patent changes the parameter of satellite search by using wireless network-derived position information to dynamically adjust which satellite frequencies and channels are searched. Instead of increasing the number of search channels hardware-wise, the system intelligently selects and prioritizes satellite channels based on the predicted visible satellites from the seed position, thereby maintaining acquisition speed without increasing hardware complexity.
3Loss of time
If A-GPS is used to reduce TTFF, then satellite acquisition time decreases, but roaming costs and compatibility issues arise
Solution Approach 1:
The patent implements self-service by using the device's existing wireless network receiver to obtain position information for GNSS satellite acquisition, rather than relying on external A-GPS infrastructure. The system uses standard wireless network broadcasting signals that are already being received by the device for other purposes, eliminating the need for separate A-GPS infrastructure and avoiding roaming costs while achieving similar TTFF reduction benefits.
Data Source
AI summary
A navigation device includes a global navigation satellite system (GNSS) receiver for receiving GNSS signals broadcast by satellites of a GNSS, a receiver for receiving location information input by a user, time information and/or wireless network coverage information and a processing device. In at least one embodiment, the processing device is arranged to determine a seed position from the location information input by a user; time information and/or wireless network coverage information and controls the GNSS receiver to acquire GNSS satellites based on the determined seed position.