PRS Timing Offset Alignment for Accurate OTDOA Positioning
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Solution Overview
Problem
As carrier frequencies increase, the symbol alignment of positioning reference signals (PRS) from multiple base stations breaks down due to significant receiving time differences, causing interference and reducing positioning accuracy in OTDOA methods.
Innovation Solution
A location server calculates and sends PRS timing offsets to adjust the transmission timing of neighbor base stations, aligning PRS symbols at the user equipment (UE) to improve orthogonality and reduce interference, allowing for accurate positioning using a single FFT window.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If carrier frequency is increased to improve data rate and spectral efficiency, then positioning accuracy deteriorates due to symbol misalignment and interference
Solution Approach 1:
The patent applies parameter changes by adjusting the PRS timing offset based on the carrier frequency. The location server calculates a timing offset value that compensates for the symbol alignment issues caused by high carrier frequencies, thereby maintaining positioning accuracy despite the increased frequency operation
Solution Approach 2:
The patent implements preliminary action by pre-calculating and applying the PRS timing offset before positioning measurements are performed. The location server determines the appropriate timing offset in advance based on the carrier frequency and applies it to the neighbor base stations, preventing symbol misalignment before it occurs
2Measurement precision
If PRS timing offset is applied to align symbols, then positioning accuracy improves, but device complexity increases due to additional timing adjustment mechanisms
Solution Approach 1:
The patent uses an intermediary approach by introducing the location server as a central coordinating entity that calculates and distributes PRS timing offsets to multiple base stations. This intermediary manages the timing alignment complexity centrally, allowing individual base stations to simply apply the provided offset without implementing complex local timing adjustment mechanisms
Solution Approach 2:
The location server performs multiple functions: it calculates PRS timing offsets, manages synchronization across base stations, and enables positioning measurements. This multi-functionality consolidates the complexity into a single entity rather than distributing it across multiple base stations
3Adaptability or versatility
If multiple FFT windows are used to handle receiving time differences, then positioning coverage is improved, but measurement complexity and processing time increase
Solution Approach 1:
The patent applies preliminary action by pre-aligning the PRS symbols from neighbor base stations using calculated timing offsets before the UE performs measurements. This preliminary alignment ensures that a single FFT window can capture all necessary PRS symbols, eliminating the need for multiple FFT windows and reducing measurement complexity
Solution Approach 2:
The patent changes the timing parameter of PRS transmission by applying offsets to neighbor base stations. This parameter adjustment aligns the PRS arrivals at the UE, allowing single-window processing while maintaining coverage for UEs with varying receiving time differences
Data Source
AI summary
Disclosed are embodiments of methods and apparatuses for positioning user equipment (UE). A method for positioning UE may comprise calculating expected receiving time differences between respective expected times for the UE to receive positioning reference signals (PRSs) from a plurality of neighbor base stations respectively and an expected time for the UE to receive a PRS from a reference base station, determining a PRS timing offset to at least partially compensate for the expected receiving time difference of at least one of the plurality of neighbor base stations, and sending the PRS timing offset to the at least one of the plurality of neighbor base stations.