Hybrid GPS PLMN Positioning Error Correction
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Solution Overview
Problem
Existing geographic localization techniques for mobile communications terminals, such as GPS and cellular networks, face challenges in accuracy, especially in urban and indoor environments due to signal obstruction and multipath propagation, making it difficult to detect outliers and maintain high precision in positioning.
Innovation Solution
A method that utilizes data from wireless communications networks to identify and discard pseudo-range measurements affected by errors, recalculating the position based on subsets of satellite signals to improve accuracy, combining GPS and PLMN data to enhance positioning accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If GPS receivers are used in urban and indoor environments, then the ability to provide location services is maintained, but the localization accuracy deteriorates due to signal obstruction and multipath propagation
Solution Approach 1:
The patent combines GPS pseudo-range measurements with PLMN (Public Land Mobile Network) measurements to create a hybrid positioning system. This merging allows the system to maintain location service capability in urban and indoor environments while improving accuracy by using complementary measurement types that are less susceptible to GPS signal obstruction and multipath effects.
Solution Approach 2:
The patent changes the measurement parameters by introducing PLMN-based measurements (such as signal strength, time of arrival, or angle of arrival from cellular base stations) alongside traditional GPS pseudo-range measurements. This parameter diversification enables accurate positioning in environments where GPS alone fails, directly addressing the accuracy deterioration problem.
2Reliability
If integrity tests are performed on GPS fixes, then the reliability of position determination is improved, but the ability to detect outliers deteriorates in environments with signal obstruction
Solution Approach 1:
The patent introduces PLMN measurements as an intermediary reference system to detect outliers in GPS measurements. By comparing GPS-derived positions with PLMN-derived positions, the system can identify inconsistent GPS measurements (outliers) that would otherwise be undetectable using traditional GPS-only integrity tests, thus maintaining outlier detection capability in signal-obstructed environments.
Solution Approach 2:
The patent implements a feedback mechanism where PLMN measurements provide continuous reference information that feeds back into the positioning process. This feedback allows the system to monitor GPS measurement quality in real-time and identify outliers by detecting deviations from the PLMN-based position estimate, thereby maintaining reliability even when GPS signals are obstructed.
3Ease of operation
If multiple pseudo-range measurements are used to calculate GPS fix, then the positioning capability is maintained, but the accuracy deteriorates when measurements are affected by errors
Solution Approach 1:
The patent applies the discarding principle by identifying and excluding erroneous pseudo-range measurements from the positioning calculation. Using PLMN measurements as a reference, the system detects outliers among GPS pseudo-range measurements and discards them, then recalculates the position using only the valid measurements. This maintains positioning capability while significantly improving accuracy by eliminating the influence of erroneous measurements.
Data Source
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AI summary
A method of determining a geographic position of a mobile communications terminal (110) operable in a wireless communications network (115,120) and comprising a receiver (210) of signals of a global navigation satellite system (105), the method comprising: calculating (315,320) a first estimated position of the mobile communications terminal based on pseudo-range measurements related to a plurality of signals received from transmitters of the global navigation satellite system; calculating a second estimated position of the mobile communications terminal based on information provided by the wireless communications network; analyzing (330,335) the first estimated position to derive an indication of whether at least one of the pseudo-range measurements is affected by errors, wherein the analyzing includes exploiting the calculated second estimated position to derive the indication; in case the indication that at least one of the pseudo-range measurements is affected by errors is obtained as a result of said analyzing (335- Y), the method comprises: calculating (340) at least one third estimated position based on pseudo-range measurements related to a respective sub-set of the plurality of signals received from transmitters of the global navigation satellite system, evaluating (345) whether the at least one third estimated position is more accurate than the first estimated position; and in the affirmative case, taking as estimated position of the mobile communications terminal the calculated third estimated position.