PRS Acquisition Offset Parameter Timing Synchronization
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Solution Overview
Problem
Mobile devices face challenges in accurately acquiring Positioning Reference Signals (PRS) without knowing the approximate timing of their transmission, which is crucial for computing a precise location in cellular networks like LTE, especially when multiple PRS configurations with different periodicities are used by neighboring cells.
Innovation Solution
A method where a mobile device receives an offset parameter from a location server indicating the timing difference between PRS positioning occasions from a reference cell and a neighboring cell, allowing it to determine the expected timing of subsequent PRS occasions and measure Reference Signal Time Difference (RSTD) based on this information, even when the neighboring cell uses multiple PRS configurations with varying periodicities.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a mobile device attempts to acquire PRS from multiple neighboring cells with different PRS configurations, then the location estimation accuracy improves, but the complexity of timing synchronization and measurement increases
Solution Approach 1:
The location server pre-calculates and provides offset parameters to the mobile device before the device attempts PRS acquisition. This preliminary provision of timing offset information enables the device to synchronize to multiple PRS configurations without having to perform complex blind searches, thereby improving location estimation accuracy while reducing device complexity
Solution Approach 2:
The location server acts as an intermediary that receives PRS configuration information from the network, processes it to determine offset parameters, and delivers this processed information to the mobile device. This intermediary role simplifies the device's task by providing pre-processed timing synchronization data, enabling accurate location estimation without increasing device complexity
2Measurement precision
If the location server provides offset parameters for multiple PRS configurations, then the RSTD measurement accuracy improves, but the signaling overhead and resource consumption increase
Solution Approach 1:
The offset parameter information is segmented and provided only for the specific PRS configuration that the mobile device needs to measure, rather than providing complete information for all possible configurations. This segmentation reduces signaling overhead while maintaining RSTD measurement accuracy for the relevant configuration
Solution Approach 2:
The location server provides offset parameters tailored to the local situation - specifically for the PRS configuration of the neighboring cell that the mobile device is attempting to measure. This localized provision of information ensures measurement accuracy while avoiding the resource consumption of providing unnecessary offset parameters for other configurations
Data Source
AI summary
Disclosed are methods for aiding a mobile device in the acquisition of positioning reference signals (PRSs) transmitted in a cellular network in support of OTDOA positioning. In one implementation, a mobile device receives an offset parameter from a location server indicative of a difference in timing between transmission of a first PRS positioning occasion for a reference cell and transmission of a second PRS positioning occasion for a neighboring cell that supports multiple PRS configurations, where the second PRS positioning occasion is for a PRS configuration with a longest periodicity. The mobile device may determine an expected timing of PRS positioning occasions for other PRS configurations for the neighboring cell based on the offset parameter and may measure a Reference Signal Time Difference for the neighboring cell using the expected timing.