UE Location Accuracy in 5G OTDOA via RTD Segmentation
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Solution Overview
Problem
In asynchronous wireless networks, determining Real Time Differences (RTDs) between base stations is challenging due to the lack of standards support for measurement and delivery, which hinders accurate Observed Time Difference of Arrival (OTDOA) location determination for user equipment (UE) without Global Navigation Satellite System (GNSS) availability, such as indoors or in dense urban areas.
Innovation Solution
The method involves using Round Trip Time (RTT) measurements to calculate RTDs, where the UE measures Reference Signal Time Differences (RSTDs) and RTTs to determine its location using OTDOA, with periodic intervals for measurement and updating to manage clock drift and accuracy, and employing fast crowdsourcing for improved RTD measurements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If RTD measurements are performed frequently to maintain location accuracy, then location precision is improved, but network load increases
Solution Approach 1:
The patent segments the measurement process into two distinct periodic intervals: a first periodic interval for RTD measurements and a second periodic interval for OTDOA location determination. This segmentation allows RTDs to be updated less frequently while still supporting accurate location tracking, thereby reducing network load while maintaining location precision.
Solution Approach 2:
The patent implements periodic measurements at different frequencies: RTD measurements occur at a first periodic interval, while OTDOA location determination occurs at a second periodic interval. This periodic action with varying frequencies optimizes the balance between location accuracy and network resource consumption.
2Productivity
If RTD measurements are performed less frequently to reduce network load, then network efficiency is improved, but location accuracy deteriorates due to clock drift
Solution Approach 1:
The patent performs preliminary RTD measurements at a first periodic interval to establish baseline timing differences between base stations. These pre-determined RTDs are then used to support subsequent OTDOA location determinations at a second periodic interval, compensating for clock drift effects and maintaining location accuracy despite less frequent measurements.
Solution Approach 2:
The system uses the measured RTDs as feedback to correct and improve OTDOA location determinations. By continuously updating RTDs at the first periodic interval and applying them to location calculations at the second periodic interval, the system compensates for timing drift and maintains accuracy.
3Loss of time
If UE performs location determination at high frequency to provide low latency location services, then service responsiveness is improved, but device energy consumption increases
Solution Approach 1:
The patent segments the location determination process into distinct measurement phases (RTD measurement at first periodic interval) and calculation phases (OTDOA determination at second periodic interval). This segmentation allows the UE to perform intensive measurements less frequently while maintaining the ability to provide timely location updates.
Solution Approach 2:
The patent implements periodic location determination with optimized intervals: RTDs are measured at a first periodic interval and then reused for multiple OTDOA calculations at a second periodic interval. This periodic approach reduces the frequency of energy-intensive measurements while maintaining location service responsiveness.
Data Source
AI summary
A user equipment (UE) periodically obtains its location using UE based Observed Time Difference of Arrival (OTDOA). The location is based on Reference Signal Time Differences (RSTDs) measured by the UE for downlink (DL) signals transmitted by each of a plurality of base stations, and the most current Real Time Differences (RTDs) for pairs of base stations. The RTDs may be determined by the UE using the RSTD measurements and Round Trip Time (RTT) measurements determined by a network entity or by the UE. The RTDs may be determined less frequently than the UE location to reduce network and UE load. Location of the UE may be improved based on testing a rate of change for each of the RTDs. The RTD determination may be improved using measurements from a plurality of UEs.