Mobile Device Downlink Positioning Signal Integration
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Solution Overview
Problem
Wireless communication systems face challenges in accurately determining the location of a user equipment (UE) using coherent and non-coherent signal integration, particularly due to frequency errors and interference, which affect the choice between coherent and non-coherent integration methods for improved measurement accuracy in terrestrial radio location methods like OTDOA.
Innovation Solution
A method is described where a mobile device obtains positioning assistance data from a server, including frequency error characteristics for cell transceivers, to determine the usage of coherent integration for measuring downlink signals, optimizing the integration technique based on the provided error information to enhance location measurement accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If coherent integration is used to improve signal-to-noise ratio and measurement accuracy, then measurement precision is improved, but reliability deteriorates when frequency errors are present
Solution Approach 1:
The patent implements dynamic selection between coherent and non-coherent integration methods based on real-time assessment of frequency error characteristics. The system adapts its integration approach by evaluating whether the frequency error between the UE's clock and the base station's carrier frequency falls within a threshold range, switching to non-coherent integration when errors are detected and to coherent integration when errors are minimal, thereby optimizing both measurement precision and reliability under varying conditions.
2Reliability
If non-coherent integration is used to improve robustness to frequency errors, then reliability is improved, but measurement precision deteriorates
Solution Approach 1:
The patent changes the integration parameter (coherent vs. non-coherent) based on the frequency error parameter. By monitoring the frequency error characteristics provided in positioning assistance data and comparing them against predetermined thresholds, the system dynamically adjusts the integration method parameter to optimize the trade-off between reliability and measurement precision for each specific measurement scenario.
3Ease of operation
If the UE uses its own frequency source for integration, then ease of operation is improved, but measurement precision deteriorates due to frequency differences
Solution Approach 1:
The patent incorporates feedback from the network regarding the base station's carrier frequency characteristics into the UE's measurement process. The network provides frequency error information in positioning assistance data, which the UE uses to adjust its integration strategy. This feedback mechanism allows the UE to maintain operational independence while compensating for frequency source differences to preserve measurement precision.
Data Source
AI summary
Techniques are discussed for conveying frequency error characteristics for a plurality of cell transceivers from a server to a mobile device to enable the mobile device to determine an optimum or near optimum period of coherent integration of a downlink signal from one or more of the plurality of cell transceivers based on the frequency error characteristics. The coherent integration of the downlink signal may be to support a downlink terrestrial positioning method such as the Observed Time Difference of Arrival (OTDOA) method for Long Term Evolution (LTE) and the downlink signal may be a Positioning Reference Signal (PRS). A mobile device may perform downlink signal integration for longer periods than the optimum period for coherent integration by combining coherent integration results using non-coherent integration. The optimum period may achieve maximum or near maximum signal to noise ratio.