Assistance Data Cell Selection Based on Interference Estimates
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Solution Overview
Problem
Conventional LTE OTDOA positioning systems face inaccuracies due to interference from neighbor cells, as they rely on rudimentary logic for selecting cells for assistance data, which can include cells with strong interference, affecting the accuracy of position fixes.
Innovation Solution
A location server is configured to estimate the position of a mobile device and assess expected interference from candidate cells, selecting a subset based on interference levels to generate assistance data that includes Physical Cell IDs for improved positioning measurements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional rudimentary logic is used for selecting neighbor cells based on distance, then the selection process is simple and fast, but the positioning accuracy deteriorates due to inclusion of high-interference cells
Solution Approach 1:
The location server performs preliminary interference estimation for each candidate cell before final selection. This preliminary action involves calculating expected interference levels using path loss models and cell configuration data, allowing the system to pre-filter unsuitable cells before committing to the final assistance data set, thereby improving positioning accuracy without excessive complexity
Solution Approach 2:
An interference estimation mechanism is introduced as an intermediary between the simple distance-based selection and the final cell selection. This intermediary evaluates candidate cells by computing expected interference levels based on path loss, cell power, and geometric relationships, serving as a mediator that filters out high-interference cells while maintaining a manageable selection process
2Reliability
If more neighbor cells are included in assistance data, then the positioning reliability improves, but the interference effects worsen and reduce measurement accuracy
Solution Approach 1:
The system changes the selection parameter from simple distance-based criteria to interference-level-based criteria. By calculating expected interference levels for each candidate cell using path loss models and cell configuration parameters, the system transforms the selection process to prioritize low-interference cells, thereby maintaining positioning reliability while minimizing harmful interference effects
Solution Approach 2:
The invention converts the potentially harmful effect of including multiple neighbor cells into a benefit by systematically evaluating and selecting only those cells with acceptable interference levels. The interference estimation process transforms what could be a harmful factor (multiple cells causing interference) into a useful selection criterion for identifying the optimal subset of positioning cells
Data Source
Figure 1
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Figure 2C~2D
AI summary
A method for assisting a mobile device to perform positioning measurements on positioning signals periodically transmitted by at least some of a plurality of cells in a wireless communication network includes determining an estimated position of the mobile device and then determining a first set of candidate cells of the plurality of cells based on the estimated position of the mobile device. The method also includes estimating an expected interference of each respective positioning signal that is transmitted by each candidate cell of the first set and selecting a subset of cells from the first set of candidate cells based on the estimated expected interference. Assistance data identifying the selected subset of cells is then generated and sent to the mobile device.