GPS Positioning Terminal Satellite Selection and Server Load Reduction
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Solution Overview
Problem
Existing GPS positioning systems face challenges in miniaturization and cost reduction due to the need for high-end CPUs for calculations, and server-assist systems waste CPU time when satellite arrangements are unfavorable, leading to inefficient position calculations.
Innovation Solution
A positioning system where a terminal requests and receives aiding information from a server only when position calculations are possible, allowing the server to perform calculations only when successful, and the terminal selects satellites based on parameters like signal intensity and elevation to minimize PDOP, reducing unnecessary server load.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a high-end CPU is used for positioning calculations, then positioning accuracy and reliability are improved, but device size and cost increase
Solution Approach 1:
The positioning system is segmented into terminal-side functions (satellite acquisition, basic information extraction) and server-side functions (positioning calculation). This divides the computational burden, allowing the terminal to use a low-end CPU while the server handles complex calculations, resolving the contradiction between positioning reliability and device complexity.
Solution Approach 2:
A server acts as an intermediary between GPS satellites and the positioning terminal. The server receives positioning basic information from satellites, performs complex positioning calculations, and returns position results to the terminal. This intermediary approach enables accurate positioning without requiring high-end CPUs in portable devices.
2Reliability
If all GPS satellite information is transmitted to the server, then complete positioning data is available, but server load increases
Solution Approach 1:
Only the essential positioning basic information (pseudorange, satellite ephemeris, clock correction) is extracted and transmitted to the server, rather than all raw GPS satellite data. This extraction principle reduces the data volume and server processing load while maintaining sufficient information for accurate positioning calculations.
Solution Approach 2:
The terminal performs partial positioning calculations locally using acquired satellite information to determine whether positioning is feasible before transmitting data to the server. This partial action filters out unnecessary transmissions, reducing server load while maintaining positioning reliability when conditions are favorable.
3Productivity
If the server performs position calculations regardless of satellite arrangement, then all positioning requests are processed, but CPU time is wasted when positioning is impossible
Solution Approach 1:
The terminal performs preliminary assessment of satellite acquisition conditions and positioning feasibility before transmitting requests to the server. By evaluating satellite geometry and signal quality in advance, the terminal filters out requests where positioning is unlikely to succeed, preventing wasted server CPU time while maintaining high processing efficiency for viable requests.
4Ease of operation
If satellite selection is based only on elevation or signal intensity, then selection is simple, but positioning may fail due to unfavorable satellite geometry
Solution Approach 1:
The satellite selection criteria are changed from simple parameters (elevation angle, signal intensity alone) to a composite evaluation including PDOP (Position Dilution of Precision). This parameter change maintains computational simplicity while significantly improving positioning success rate by accounting for satellite geometric distribution, resolving the contradiction between ease of operation and positioning reliability.
Data Source
AI summary
A positioning system that uses a positioning terminal, an information provision device, and a communication network. The information provision device is configured to perform position calculations for the positioning terminal only when the results of position calculations can be considered to be successful. Thus, a load on the information provision device can be reduced.