Wireless Terminal Location Estimation Using Propagation Delay
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Solution Overview
Problem
In wireless telecommunications systems with distributed and/or repeater antennas, existing techniques fail to accurately determine the location of a wireless terminal as the signals from multiple antennas are indistinguishable, making it difficult for both the user and remote parties to ascertain the terminal's location.
Innovation Solution
The system employs location-dependent traits such as propagation delay and signal strength to differentiate between possible locations, using a data processing system to designate improbable locations and estimate the terminal's position based on these traits, thereby disambiguating the radiating source of the signal.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If distributed and/or repeater antennas are deployed to extend signal coverage, then the area in which the signal is receivable and decodable is increased, but the ability to identify the specific radiating source is lost
Solution Approach 1:
The patent segments the signal identification problem by assigning unique identifiers to different propagation paths rather than to individual antennas. The location estimation function breaks down the ambiguous signal into discrete path components, each with identifiable characteristics (delay, strength, angle of arrival), allowing the system to segment the coverage area into distinct spatial zones associated with different base stations.
Solution Approach 2:
The patent introduces location estimation as an intermediary process between signal reception and source identification. Instead of directly identifying which antenna radiated the signal, the system uses location estimation based on propagation characteristics as a mediator to infer the radiating source. This intermediary function resolves the information loss by providing indirect but reliable source identification through spatial reasoning.
2Area of stationary object
If multiple antennas radiate the same signal, then signal coverage is extended, but location estimation accuracy deteriorates due to indistinguishable signals
Solution Approach 1:
The patent transitions from two-dimensional signal strength-based location estimation to three-dimensional estimation by incorporating propagation delay and angle of arrival measurements. This additional dimensional information (time and angular space) allows the system to disambiguate signals from multiple antennas, maintaining location estimation accuracy even when multiple antennas radiate the same signal across extended coverage areas.
Solution Approach 2:
The patent changes the parameters used for location estimation from simple signal strength to a composite set including propagation delay, signal strength, and angle of arrival. By changing these measurement parameters, the system can distinguish between signals from different antennas even when they transmit identical content, thereby maintaining estimation precision across expanded coverage zones.
3Measurement precision
If propagation delay measurement is used to estimate location, then location-dependent differentiation is enabled, but complexity in disambiguating multiple signal paths increases
Solution Approach 1:
The patent applies preliminary action by pre-calculating and storing propagation delay characteristics for different locations and paths before actual location estimation is needed. The system prepares reference data about expected delay patterns from various base stations and antennas, so that during operation, the location estimation function can quickly match measured delays against pre-computed references without performing complex real-time path analysis.
Solution Approach 2:
The location estimation function serves itself by using the measured propagation delay to automatically identify which signal paths are relevant, eliminating the need for external assistance in path disambiguation. The system self-determines the radiating source by comparing measured delay characteristics against stored reference data, reducing overall system complexity while maintaining high location differentiation capability.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach effectively reduces ambiguity in identifying the signal source and estimates the wireless terminal's location accurately, even in environments with multiple antennas transmitting the same signal, enhancing location-based services like emergency response.
Implementation Method 1
receiving a measure of a propagation delay of a first signal traveling between a wireless terminal and a base station
Implementation Method 2
measuring one or more location-dependent traits associated with a second signal received by the wireless terminal
Data Source
AI summary
A technique for estimating the location of a wireless terminal at an unknown location in a geographic region is disclosed. The technique is based on the recognition that there are location-dependent traits of electromagnetic signals. In environments where multiple antennas are radiating the same signal, as in the case of distributed antennas or host-repeater configurations, one or more possible locations of the wireless terminal can be designated as improbable based on i) a measure of the propagation delay of a signal traveling between a) a base station and b) the wireless terminal or an infrastructure antenna, or ii) the maximum distance at which a signal is detectable by the wireless terminal. Additionally, the applicable set of values for the location-dependent traits is selected based on similar criteria.