Partially Synchronized RF Multilateration for Indoor Location Accuracy
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Solution Overview
Problem
Existing wireless communication systems face inaccuracies in locating objects indoors due to time synchronization errors, which are not adequately addressed by current LTE standards, falling short of the stringent accuracy requirements for Location-Based Services (LBS) and Real Time Locating Service (RTLS) systems.
Innovation Solution
The implementation of a method and system that uses partially synchronized receivers and transmitters in clusters, employing software-defined radio and digital signal processing technologies, allowing for precise time synchronization within clusters while relaxing inter-cluster synchronization requirements, and utilizing narrow bandwidth ranging signals to enhance location accuracy in wireless networks, including LTE networks.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If complete and precise time synchronization is implemented across all transmitters and receivers, then location accuracy is improved, but system complexity and cost increase
Solution Approach 1:
The system divides the network into multiple clusters, each with its own synchronized transmitters and receivers. Within each cluster, complete time synchronization is maintained to ensure accurate location measurements, while inter-cluster synchronization requirements are relaxed. This segmentation allows the system to achieve high location accuracy locally without requiring complex global synchronization infrastructure.
Solution Approach 2:
The patent implements differentiated synchronization quality at different levels: high-precision time synchronization is maintained within each cluster (local quality) where location measurements are performed, while inter-cluster synchronization uses lower precision. This local quality approach ensures that the critical measurement function operates with high accuracy while reducing overall system complexity and cost.
2Manufacturing precision
If 100% time synchronization is required across the entire system, then ranging accuracy is improved, but system cost and complexity increase significantly
Solution Approach 1:
The system applies time synchronization partially rather than completely across the entire network. Each cluster maintains 100% time synchronization among its members, which is sufficient for accurate ranging measurements within that cluster. However, the system does not require 100% synchronization across all clusters, thereby reducing implementation complexity and cost while maintaining adequate ranging accuracy for the application.
3Measurement precision
If narrow bandwidth ranging signals are used, then location accuracy is improved, but signal propagation range is reduced
Solution Approach 1:
The patent combines multiple narrow bandwidth ranging signals from different transmitters within a cluster to achieve both high location accuracy and extended operating range. By merging the coverage areas of multiple synchronized transmitters, the system maintains the accuracy benefits of narrow bandwidth signals while expanding the overall service area through cooperative transmission.
Data Source
AI summary
Systems and methods for determining a location of one or more user equipment (UE) in a wireless system can comprise receiving reference signals via a location management unit having two or more co-located channels, wherein the two or more co-located channels are tightly synchronized with each other and utilizing the received reference signals to calculate a location of at least one UE among the one or more UE. Embodiments include multichannel synchronization with a standard deviation of less than or equal 10 ns. Embodiments can include two LMUs, with each LMU having internal synchronization, or one LMU with tightly synchronized signals.