Distributed RAN TOA Positioning With Clock Discrepancy Compensation
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Solution Overview
Problem
Existing time of arrival (TOA) calculations in distributed RAN/cloud system architectures face challenges due to asynchronous eCPRI interfaces and long distances between DU and RU components, leading to unpredictable delays and reduced accuracy in propagation delay measurements.
Innovation Solution
A new algorithm for TOA T0 calculation that compensates for reference clock discrepancies between the DU and RU by using over-the-air transmission time (Ra) as a reference, adjusting for potential delays with a factor Δ(Ta;Tb), and provides TOA T0 corrections to UEs for improved accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If distributed RAN/cloud system architecture is used with asynchronous eCPRI interfaces and long distances between DU and RU components, then system flexibility and deployment options are improved, but propagation delay measurement accuracy deteriorates due to unpredictable delays
Solution Approach 1:
The patent applies preliminary action by calculating and compensating for the reference signal transmission delay (TOA T0) in advance at the base station before actual positioning measurements are performed. The base station determines TOA T0 based on the last received packet timing from the DU and reference clock synchronization status, then provides this compensation value to the UE. This preliminary compensation eliminates the need for the UE to perform complex round-trip time measurements, thereby improving propagation delay measurement accuracy while maintaining the flexibility of distributed RAN architecture.
Solution Approach 2:
The patent implements feedback by continuously monitoring the reference clock synchronization status between DU and RU, and adjusting the TOA T0 calculation accordingly. The base station receives feedback about packet arrival times from the DU and uses this information to dynamically update the transmission delay compensation value. This feedback mechanism ensures that even with asynchronous interfaces and varying distances in distributed RAN, the propagation delay measurements remain accurate.
2Stability of the object's composition
If reference clock synchronization is implemented between DU and RU in distributed RAN, then time alignment is improved, but device complexity increases due to additional synchronization mechanisms
Solution Approach 1:
The patent uses the base station as an intermediary that centralizes the timing reference function. Instead of requiring direct synchronization between DU and RU reference clocks, the base station acts as a mediator that receives timing information from the DU, calculates the appropriate TOA T0 compensation based on packet arrival times and reference clock status, and provides this compensation to the UE. This intermediary approach simplifies the synchronization architecture while maintaining time alignment accuracy.
Solution Approach 2:
The patent applies parameter changes by dynamically adjusting the TOA T0 compensation value based on the synchronization status of reference clocks. When reference clocks are synchronized, the system uses one calculation approach; when they are not synchronized or when packet delays occur, the system changes the parameter (TOA T0) to reflect the actual transmission timing. This parameter adaptation allows the system to maintain time alignment without requiring complex permanent synchronization mechanisms.
Data Source
AI summary
Example embodiments provide a method to determine a reference signal transmission delay by a base station for a distributed RAN or cloud system architecture. The method uses an over the air transmission time and compensates for a possible reference clock discrepancy. Further, a method for TOA-based propagation delay measurement is provided, where consecutive reference signal transmission delays have a variable pattern or high precision is needed. Apparatuses, methods, and computer programs are disclosed.