PRS FFT Window Offset Adjustment for Accurate RSTD Measurement
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Solution Overview
Problem
Reception of positioning reference signals (PRS) in wireless networks is impaired by channel noise and interference, affecting the accuracy of reference signal time difference (RSTD) measurements.
Innovation Solution
A user equipment (UE) determines RSTD values without tying the Fast Fourier Transform (FFT) window to serving cell symbol timing, using an expected RSTD value and uncertainty to identify a search interval and adjust the FFT window offset for decoding PRS within this interval.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the FFT window is tied to serving cell symbol timing for PRS reception, then the device complexity is reduced and operation is simplified, but the measurement precision of RSTD values deteriorates due to channel noise and interference
Solution Approach 1:
The FFT window timing is made dynamic by allowing flexible adjustment of the FFT window offset independently from serving cell symbol timing. The UE can adaptively determine optimal FFT window positions based on expected RSTD values and uncertainties, enabling the system to respond to varying channel conditions and improve measurement precision without fixed timing constraints
Solution Approach 2:
The invention changes the timing parameter of the FFT window by introducing an adjustable offset that decouples it from serving cell symbol timing. By modifying the FFT window position parameter based on RSTD expectations and uncertainties, the system optimizes PRS reception accuracy while maintaining manageable complexity through structured parameter adjustment
2Reliability
If the FFT window is tied to serving cell symbol timing, then the ease of operation is improved, but the reliability of PRS reception deteriorates in the presence of channel noise and interference
Solution Approach 1:
The system dynamically adjusts FFT window timing based on RSTD expectations and uncertainties, allowing the UE to adapt to varying channel conditions. This dynamic approach improves PRS reception reliability by positioning the FFT window optimally, while the structured method of adjustment maintains operational simplicity
Solution Approach 2:
The UE performs preliminary determination of RSTD expectations and uncertainties before PRS reception. This preliminary action allows the system to pre-position the FFT window optimally, improving reception reliability in advance while maintaining ease of operation through automated preliminary configuration
3Measurement precision
If the FFT window offset is adjusted based on RSTD expectations and uncertainties, then the measurement precision of RSTD values is improved, but the device complexity increases due to additional processing requirements
Solution Approach 1:
The invention focuses on changing specific timing parameters (FFT window offset) based on RSTD expectations and uncertainties, rather than overhauling the entire signal processing system. This targeted parameter adjustment improves measurement precision while limiting the increase in processing complexity to only the necessary offset calculation and application
Data Source
AI summary
A user equipment (UE) associated with a wireless network determines a first reference signal time difference value. The UE determines a first RSTD estimate and a first RSTD uncertainty associated with the first RSTD value, identifies a search interval for the first RSTD value, the search interval extending from a difference between the first RSTD estimate and the first RSTD uncertainty to a sum of the first RSTD estimate and the first RSTD uncertainty, receives wireless signals during the identified search interval, determines a Fast Fourier Transform (FFT) window offset for decoding a first positioning reference signal (PRS) received during the identified search interval, and determines the first RSTD value based at least in part on the determined FFT window offset.