OTDOA Positioning Using Ambiguous Cell Measurements
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Solution Overview
Problem
Existing wireless communication systems face challenges in accurately locating user equipment (UE) due to the presence of duplicated Radio Frequency (RF) signals from ambiguous cells, such as Distributed Antenna Systems (DAS), Remote Radio Heads (RRHs), repeaters, and relays, which cannot be distinguished, leading to discarded measurements and reduced positioning accuracy in OTDOA and AFLT methods.
Innovation Solution
The method involves providing location assistance data to the UE that includes ambiguous cells, requesting and receiving measurements, and calculating the UE's position based on these measurements, using techniques like Observed Time Difference of Arrival (OTDOA) and Advanced Forward Link Trilateration (AFLT), even when signals from ambiguous cells are received, by identifying the most likely antenna source and adjusting for signal propagation delays.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If measurements from ambiguous cells are discarded to avoid positioning errors, then positioning reliability is improved, but positioning accuracy deteriorates due to loss of useful measurement data
Solution Approach 1:
The patent changes the parameter of cell identification by introducing a reference signal timing difference (RSTD) threshold. Instead of discarding all ambiguous cell measurements, the system compares measured RSTD values against expected thresholds to determine whether to include measurements from ambiguous cells, thereby improving positioning accuracy while maintaining reliability
Solution Approach 2:
The patent introduces an intermediary classification mechanism that categorizes cells as either ambiguous or non-ambiguous based on RSTD comparisons. This intermediary classification allows the system to selectively use measurements from ambiguous cells when they meet certain criteria, rather than universally discarding or accepting them
2Measurement precision
If all available base station signals are used for positioning, then positioning accuracy is improved, but device complexity increases due to need for signal source identification
Solution Approach 1:
The patent implements a self-service mechanism where the UE automatically performs RSTD measurements and comparisons to identify ambiguous cells without requiring complex network assistance or manual configuration. The device autonomously determines which measurements to use based on pre-configured cell information and measured timing differences
Solution Approach 2:
The patent segments the positioning process into distinct stages: obtaining cell information, measuring RSTD values, comparing against thresholds, and selectively using measurements. This segmentation simplifies the overall complexity by breaking down the signal processing into manageable, independent steps
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 enables the use of measurements from ambiguous cells, increasing location accuracy by accounting for signal strengths and propagation conditions, even when signals from multiple sources are received, thereby improving positioning reliability in areas with duplicate signals.
Implementation Method 1
Observed Time Difference of Arrival (OTDOA) is a multilateration method in which the UE measures the time difference between specific signals (e.g. positioning reference signals) from several eNodeBs
Data Source
AI summary
Techniques are discussed for supporting positioning with ambiguous wireless cells. An ambiguous cell may employ a Distributed Antenna System (DAS), one or more Remote Radio Heads (RRHs), repeaters or relays, or may broadcast the same Positioning Reference Signal (PRS) as another nearby cell. In example techniques, measurements of a radio source in an ambiguous cell (e.g. a DAS antenna element or RRH) may be used to identify the measured radio source. The measurements may be for the Observed Time Difference of Arrival (OTDOA) position method or the Enhanced Cell ID (ECID) position method. The determination of the measured radio source for an ambiguous cell may be used to improve a location estimate for a user equipment (UE).