LTE Synthetic Aperture Navigation for Indoor Localization
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Solution Overview
Problem
Current indoor localization technologies face challenges in accurately determining position indoors due to multipath delays and unknown clock biases in LTE signals, limiting their effectiveness for precise navigation.
Innovation Solution
The implementation of a Long-Term Evolution Synthetic Aperture Navigation (LTE-SAN) framework that uses carrier phase measurements and synthetic aperture antenna arrays to suppress multipath errors by determining the direction of arrival of LTE signals, employing feedforward and feedback coupling schemes and extended Kalman filters for accurate navigation observables.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If LTE carrier phase measurements are used for indoor localization, then position accuracy is improved, but multipath errors worsen the measurement precision
Solution Approach 1:
The patent segments the received LTE signal into multiple components corresponding to different propagation paths (line-of-sight and multipath). By separating and independently processing these signal components, the system can identify and utilize the direct path signal while rejecting multipath contributions, thereby resolving the contradiction between using carrier phase measurements for high accuracy and suffering from multipath errors.
Solution Approach 2:
The patent implements feedback mechanisms where the estimated position and velocity are continuously updated based on processed carrier phase measurements. The system uses feedback loops to refine multipath rejection and improve measurement precision iteratively, allowing the navigator to adapt to changing indoor environments and maintain high position accuracy despite multipath challenges.
2Measurement precision
If synthetic aperture antenna array is used to suppress multipath errors, then measurement precision is improved, but device complexity increases
Solution Approach 1:
The patent employs synthetic aperture antenna array technology that creates a virtual array in the spatial domain by moving a single physical antenna through multiple positions. This transforms a one-dimensional problem into a multi-dimensional solution, enabling multipath rejection capabilities typically requiring multiple simultaneous antennas to be achieved with a single moving antenna, thus reducing device complexity while maintaining measurement precision.
Solution Approach 2:
The patent creates a synthetic copy of the antenna array by recording and processing signals collected at different antenna positions over time. This temporal copying approach reconstructs the spatial information that would require multiple physical antennas, achieving multipath suppression capabilities with a single physical antenna and reducing overall system complexity.
3Measurement precision
If direction of arrival determination is used to suppress multipath errors, then position accuracy is improved, but processing complexity increases
Solution Approach 1:
The patent performs preliminary determination of the direction of arrival (DOA) of the direct path signal before final position calculation. By pre-processing the carrier phase measurements to extract DOA information and identify the line-of-sight component, the system simplifies subsequent position computation and reduces the complexity of real-time processing while maintaining high position accuracy.
Data Source
AI summary
A spatial approach is provided to mitigate multipath error for an indoor pedestrian localization system using broadband communication signals, such as cellular long-term evolution (LTE) carrier phase measurements. Motion of a receiver may be used to synthesize an antenna array from time-separated elements. Received data may then be combined for synthetic aperture navigation that allows for suppressing multipath error based on determination of direction-of-arrival (DOA) of the incoming communication (e.g., LTE) signals. In one embodiment, navigation observables may be determined based on determined direction of arrival.