Satellite Ephemeris Data Selection for Positioning Accuracy
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current satellite positioning systems face challenges in providing accurate assistance data, especially during roaming when the mobile station is outside its home operator's coverage area, leading to issues with satellite visibility and expired ephemeris data, which can be costly and dependent on external reference networks.
Innovation Solution
A method where a server station decides whether to transmit broadcast ephemeris data or long-term ephemeris data based on the requested accuracy, using satellite orbit predictions to extend the data validity period, reducing bandwidth usage and eliminating the need for a global reference network, and allowing a single reference receiver to provide accurate assistance data.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If broadcast ephemeris data are transmitted to the mobile station, then position fix accuracy is improved, but communication channel capacity is consumed
Solution Approach 1:
The patent changes the temporal parameter of ephemeris data by transmitting long-term valid ephemeris data instead of short-term broadcast ephemeris data. This parameter change extends the validity period significantly, reducing the frequency of transmissions and thus conserving communication channel capacity while maintaining position fix accuracy within acceptable bounds.
Solution Approach 2:
The patent performs preliminary computation of long-term ephemeris data using satellite orbit predictions before transmission. By pre-computing extended validity ephemeris data at the server station using orbital mechanics models, the system reduces the need for frequent updates, thereby reducing communication channel usage while ensuring accuracy is maintained within specifications.
2Reliability
If a global reference network is deployed to provide assistance data during roaming, then position fix reliability is improved, but device complexity and cost increase
Solution Approach 1:
The patent makes the single reference receiver universal by using satellite orbit predictions that are valid globally. The computed long-term ephemeris data based on orbital mechanics can be used anywhere on Earth, eliminating the need for multiple geographically distributed reference receivers. This multi-functional approach maintains reliability during roaming without increasing network complexity.
Solution Approach 2:
The patent creates a virtual global reference network by computing ephemeris data from satellite orbit predictions rather than physically deploying reference receivers worldwide. The orbital prediction models serve as a virtual copy of the reference network functionality, providing global coverage through computation rather than physical infrastructure.
3Measurement precision
If ephemeris data are transmitted frequently to maintain accuracy, then position fix accuracy is improved, but communication bandwidth is consumed
Solution Approach 1:
The patent fundamentally changes the time validity parameter of ephemeris data from short-term (broadcast) to long-term (computed from orbital predictions). This parameter transformation reduces the update frequency requirement, thereby reducing bandwidth consumption while maintaining accuracy within specification limits over the extended validity period.
Data Source
AI summary
Satellites of a satellite positioning system broadcast within the navigation signals ephemeris data having a certain period of validity. At a mobile station, ephemeris data are required for position-fixing. In assisted satellite positioning systems, acquisition of navigation signals emitted by the satellites is facilitated as assistance data are provided to the mobile station. At a server station, a request for assistance data issued by the mobile station is received, and the server station transmits ephemeris data as part of the assistance data to the mobile station in response to its request. Upon receiving the request for assistance data issued by the mobile station, the server station decides whether the mobile station could achieve a specified position fix accuracy if the mobile station was provided with the broadcast ephemeris data. In the positive, the server station transmits the broadcast ephemeris data to the mobile station. In the negative, the server station transmits, instead of broadcast ephemeris data, long-term ephemeris data to the mobile station as part of the assistance data requested. The long-term ephemeris data are derived from satellite orbit predictions and have a period of validity substantially increased with respect to the ephemeris data broadcast by the satellites.