Multiple Range Estimation Location for Mobile Station Positioning
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Solution Overview
Problem
Existing location estimation techniques for mobile devices are hindered by signal multipath and non-line of sight issues, leading to inaccurate location estimates, especially when the time of transmission is unknown or cannot be determined.
Innovation Solution
The method employs Multiple Range Estimation Location (MREL) by determining the time of transmission using a functional relationship between the forward and reverse channels, generating Range Rings that account for errors and mitigate multipath interference, thereby avoiding differencing operations and ambiguity problems present in Time Difference of Arrival (TDOA) methods.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If Time Difference of Arrival (TDOA) method is used to estimate location when time of transmission is unknown, then location estimation can be performed without knowing transmission time, but measurement precision deteriorates due to hyperbolic intersection ambiguity and multipath interference
Solution Approach 1:
The system performs preliminary synchronization between the mobile device and access point before location estimation. The access point transmits downlink signals that enable the mobile device to synchronize its timing, and the mobile device transmits uplink signals with known timing relationships. This preliminary synchronization establishes a functional relationship that allows determination of transmission time, thereby enabling more precise range-based location estimation without suffering from TDOA's hyperbolic ambiguity
Solution Approach 2:
The patent introduces an intermediary functional relationship f(P) between downlink and uplink signal timing. This functional relationship acts as a mediator that connects the known downlink transmission time with the uplink transmission time, allowing the system to determine the mobile device's transmission time indirectly through the synchronized timing relationship established by the access point
2Measurement precision
If Range Rings method is used with known transmission time to achieve accurate location estimates, then measurement precision improves, but device complexity increases due to synchronization requirements
Solution Approach 1:
The patent merges the location estimation function with the existing cellular communication synchronization mechanism. The same downlink and uplink signal exchanges used for timing synchronization in cellular networks are also utilized for location estimation. By combining these functions, the system achieves range-based location estimation accuracy without requiring separate complex synchronization hardware or protocols
Solution Approach 2:
The functional relationship f(P) between downlink and uplink timing serves multiple purposes: it enables both timing synchronization for cellular communication and provides the basis for accurate range-based location estimation. This multi-functionality allows the same signal exchange mechanism to achieve both communication reliability and precise location tracking without additional system complexity
3Adaptability or versatility
If signal multipath is present in the environment, then signal propagation becomes complex with reflections off objects, but this creates harmful factors that degrade location estimation accuracy
Solution Approach 1:
The system performs preliminary identification and characterization of multipath propagation conditions by analyzing the received signal structure. Before performing location estimation, the system identifies direct line-of-sight signal components versus reflected multipath components based on their arrival times and signal characteristics, then selectively processes only the direct path signals for range calculation
Solution Approach 2:
The patent converts the harmful effect of multipath propagation into a beneficial signal structure by exploiting the time diversity it creates. The multipath reflections arrive at different times, creating a structured signal pattern that allows the receiver to distinguish between direct and reflected paths. This temporal separation transforms the harmful interference into a useful timing reference for identifying the true signal transmission time
Data Source
AI summary
A system and method of determining the location of a mobile station by determining the time of transmission of a signal by a mobile station and determining range rings at a plurality of reference stations receiving the transmitted signal, where the range rings represent the distance f the mobile station from the plurality of reference stations.