TDOA Positioning With Coordinated PRS Synchronization Error Mitigation
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Solution Overview
Problem
Existing positioning technologies in cellular networks face limitations due to network synchronization errors, which degrade the accuracy of Time Difference of Arrival (TDOA) measurements for user equipment (UE) location estimation.
Innovation Solution
The method involves configuring positioning reference signals (PRS) transmissions between a reference base station and neighboring base stations to mitigate synchronization errors by accounting for propagation and processing delays, enabling accurate determination of Reference Signal Time Difference (RSTD) through coordinated PRS transmissions and measurements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional TDOA positioning is used, then positioning can be achieved, but network synchronization errors degrade positioning accuracy
Solution Approach 1:
The patent applies preliminary action by having neighboring base stations transmit PRS in response to receiving the initial PRS from the reference base station. This coordinated transmission timing, established before the actual positioning measurement, allows the system to pre-compensate for synchronization errors by accounting for propagation and processing delays in advance, thereby improving positioning accuracy without requiring perfect real-time synchronization.
Solution Approach 2:
The patent implements feedback mechanisms where base stations report their received PRS timing information back to the network entity. This feedback loop enables the system to measure actual propagation delays and processing times, then use this information to correct synchronization errors in the RSTD calculation, thereby improving positioning accuracy while maintaining reliable error compensation.
2Measurement precision
If PRS transmissions are coordinated between base stations, then synchronization errors are mitigated, but system complexity increases
Solution Approach 1:
The patent merges the PRS transmission function into the existing base station operation framework, where neighboring base stations transmit PRS in response to receiving the initial PRS. This integration combines multiple functions (synchronization, positioning reference, and error compensation) into a unified transmission mechanism, improving RSTD measurement accuracy while avoiding the need for separate complex coordination systems.
Solution Approach 2:
The patent uses the received PRS timing information as an intermediary element that mediates between the reference base station and neighboring base stations. This intermediary timing data allows coordinated PRS transmissions without requiring direct complex communication protocols between base stations, thereby improving measurement precision while keeping the coordination mechanism relatively simple.
3Measurement precision
If processing delays are accounted for in RSTD calculation, then positioning accuracy improves, but measurement time increases
Solution Approach 1:
The patent applies preliminary action by having base stations prepare and transmit PRS signals in advance, with timing information already established before the actual measurement. This allows processing delays to be pre-characterized and accounted for in the RSTD calculation without requiring real-time processing, thereby improving positioning precision while minimizing the time added by delay compensation.
Solution Approach 2:
The patent skips the need for complex real-time delay calculation by using pre-established timing relationships and fixed processing delay models. Instead of performing elaborate delay compensation in real-time, the system uses simplified approaches that account for delays through pre-configured parameters and measured propagation times, thereby improving precision without significant time penalty.
Data Source
AI summary
Downlink and uplink Time Difference of Arrival (TDOA) is performed using Reference Signal Time Difference (RSTD) measurements. The transmissions and measurements of positioning reference signals (PRS) are configured to mitigate or eliminate network synchronization errors which conventionally limit positioning accuracy of TDOA. The synchronization errors are mitigated using inter-base station PRS, and transmission of the PRS in response to receipt of the initial reference signal. For DL TDOA, a reference base station may transmit PRS to the user equipment (UE) and neighboring base station. In response, the neighboring base station transmits PRS to the UE. The RSTD may be determined as the difference in the time of reception of the PRS signals received at the UE after removal of the total delay for transmitting the PRS by the neighboring base station, including propagation time and processing time. The RSTD for UL TDOA may be determined in a similar manner.