Total Flight Time Ratio Pattern Matching for Mobile Location
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing location estimation methods for mobile devices in wireless networks are hindered by multipath effects, which degrade the accuracy of signal transit time measurements.
Innovation Solution
The method employs a pattern matching scheme based on total flight time ratios, adjusting signal timing parameters to mitigate multipath effects by comparing measured total flight times with pre-defined patterns, and using a weighted Root Mean Square (RMS) calculation to determine the mobile device's location within a geographic region.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If signal arrival time or signal transit time measurements are used for location estimation, then location determination is enabled, but multipath effects degrade the accuracy of the location estimate
Solution Approach 1:
The system performs preliminary calibration by collecting signal measurements at multiple known grid points throughout the geographic region. These pre-collected measurements establish reference patterns of total flight time ratios that account for multipath effects specific to each location. When determining the mobile device's location, the system compares real-time measurements against these pre-established patterns, enabling accurate location estimation despite multipath interference.
Solution Approach 2:
The system transforms the location estimation problem by changing from direct signal transit time measurement to comparing total flight time ratios. Instead of relying on absolute timing measurements that are vulnerable to multipath, the system uses ratios of flight times between different base station pairs, which cancel out common multipath effects. The calibration process establishes these ratio patterns at grid points, and the mobile device's location is determined by matching observed ratios against the calibrated patterns.
2Measurement precision
If traditional signal transit time measurement methods are used, then location estimation can be performed, but accuracy is degraded by signal reflections off objects
Solution Approach 1:
The system introduces total flight time ratios as an intermediary metric between raw signal measurements and location determination. Rather than directly using signal transit times that are corrupted by reflections, the system computes ratios of flight times for different base station pairs. These ratios serve as a mediator that eliminates the impact of signal reflections, as the multipath effects appear equally in both measurements and cancel out in the ratio calculation.
Solution Approach 2:
The system creates a calibrated copy of the geographic environment by measuring and storing total flight time ratios at multiple known grid points. This calibrated dataset represents a fingerprint of the radio environment including all multipath characteristics. During operation, the system compares real-time measurements against this copied reference environment to determine location, effectively using the pre-recorded patterns as a template to match against current conditions.
Data Source
AI summary
A method and system for estimating the location of a mobile device. A range of the mobile device to a reference station may be determined as a function of the time of transmission of a first signal transmitted from a base station and as a function of the time of receipt of a second signal transmitted from the mobile device to the reference station, the second signal being a function of the first signal advanced by a timing parameter. A relationship for each of a plurality of grid points in a geographic region may be determined as a function of the determined range and a range metric. These plural grid points may contain the reference station. The determined relationship may be compared with data corresponding to each of the plural grid points, and a location of the mobile device determined as a function of the comparison.