Indoor Positioning Using Reference Terminal Time Differences
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Solution Overview
Problem
The existing Time Difference of Arrival (TDOA) method for indoor positioning in three-dimensional spaces faces challenges due to un-synchronization of base stations, leading to positioning errors, which are difficult to eliminate in current communication networks.
Innovation Solution
A positioning method that involves a positioning server receiving time instant information from multiple base stations for both the terminal to be positioned and a reference terminal at a fixed location, calculating time differences, and using these differences to eliminate synchronization errors and improve positioning accuracy by deriving distance formulas that do not require absolute time synchronization between base stations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the TDOA method is used for indoor positioning in three-dimensional spaces, then positioning function can be achieved, but positioning accuracy deteriorates due to un-synchronization of base stations
Solution Approach 1:
The patent introduces a reference terminal at a known fixed location as an intermediary element. This reference terminal sends reference signals that are received by multiple base stations, enabling the calculation of time differences without requiring absolute synchronization between base stations. The reference terminal acts as a mediator that establishes a common time reference point for all base stations, thereby resolving the synchronization problem while maintaining positioning functionality.
Solution Approach 2:
The patent changes the parameter from absolute time synchronization to relative time difference measurement. Instead of requiring base stations to be absolutely synchronized, the system measures the time difference of arrival relative to the reference terminal's signal. This parameter transformation allows the system to eliminate the need for absolute synchronization while still achieving accurate positioning through the calculated time differences.
2Measurement precision
If absolute time synchronization is implemented between base stations, then positioning accuracy is improved, but system complexity and implementation difficulty increase
Solution Approach 1:
The patent extracts the time reference function from the base station synchronization system and relocates it to the reference terminal. By taking out the absolute time synchronization requirement from the base station network, the system eliminates the need for complex inter-base-station synchronization mechanisms. The reference terminal becomes the sole time reference source, simplifying the overall system architecture.
Solution Approach 2:
The system uses the reference terminal's own transmitted signals as the basis for time difference calculation. The reference terminal self-provides the time reference that all base stations need, eliminating the requirement for external synchronization infrastructure between base stations. Each base station independently measures the time difference relative to the reference terminal's signal, making the system self-sufficient in terms of time referencing.
3Measurement precision
If more than four base stations are used for three-dimensional positioning, then positioning accuracy is improved, but the requirement for simultaneous signal acquisition increases system complexity
Solution Approach 1:
The patent performs preliminary action by having the reference terminal transmit reference signals before the actual positioning measurement. These pre-transmitted reference signals are received and processed by all base stations in advance, establishing the time reference data needed for subsequent positioning calculations. This preliminary signal transmission simplifies the simultaneous acquisition requirement by providing pre-established time reference points.
Solution Approach 2:
The patent adds the time dimension to the spatial positioning problem. By measuring the time difference of signal arrival at multiple base stations relative to the reference terminal, the system transforms the three-dimensional spatial positioning problem into a four-dimensional problem that includes time as an additional measurement dimension. This dimensional extension enables accurate 3D positioning without requiring complex simultaneous multi-base-station coordination.
Data Source
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AI summary
Embodiments of the present invention provide a positioning method. A positioning server separately receives information about time of arrival of positioning reference signals of a terminal to be positioned at positioning base stations and information about time of arrival of positioning reference signals of a reference terminal in a fixed position at the positioning base stations that are sent by N positioning base stations; N is greater than or equal to 3; the coordinate of the terminal to be positioned is calculated according to the information about time. Embodiments of the present invention also provide a positioning base station, a positioning server, and a positioning system.