UE 2D State Estimation Using Doppler and Distance Measurements
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Solution Overview
Problem
Existing positioning methods for user equipment (UE) in wireless communication systems lack high-availability and accuracy in estimating 2D position and velocity, especially indoors, and are often hindered by UE-dependent hardware or software that can be disabled, limiting the implementation of advanced services like traffic flow prediction and seamless handover management.
Innovation Solution
A method for kinematic state estimation of UE using Doppler shift and distance-establishing measurements from two different antennas of a wireless communication system, employing an Interacting Multiple Model (IMM) filtering algorithm to estimate 2D position, velocity, and frequency bias, which can be implemented in eNB or gNB without relying on UE-specific hardware or software.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If A-GNSS positioning method is used, then position estimation is provided, but availability may be switched off by user or UE vendor and performance is inferior indoors
Solution Approach 1:
The patent uses Doppler shift measurements as an intermediary mechanism to enable position and velocity estimation without relying on A-GNSS hardware or satellite signals. By measuring Doppler shifts in uplink signals from the UE at multiple base stations, the system can calculate UE velocity and combine it with distance measurements to estimate position, providing a mediator solution that works independently of A-GNSS availability
Solution Approach 2:
The patent replaces the mechanical/satellite-based A-GNSS positioning system with a radio-based Doppler shift measurement system. Instead of relying on satellite signals and specialized receivers, the system uses standard cellular uplink signals and base station equipment to perform positioning, substituting one physical measurement mechanism with another that is more readily available in cellular networks
2Reliability
If U-TDOA or OTDOA positioning methods are used, then position estimation is provided, but velocity information is not provided and availability is limited by detectability requirements in at least 4 base stations
Solution Approach 1:
The patent segments the positioning problem into two separate measurement components: Doppler shift measurements for velocity estimation and distance measurements for position estimation. This segmentation allows the system to obtain both velocity and position information independently, with Doppler measurements providing velocity data that TDOA methods cannot provide
Solution Approach 2:
The patent introduces Doppler shift measurements as an intermediary that bridges the gap between position estimation and velocity estimation. By measuring the frequency shift caused by UE motion, the system can derive velocity information that complements position data from distance measurements, providing complete kinematic state information
3Adaptability or versatility
If A-GNSS or TDOA methods are used, then positioning is provided, but UE-dependent hardware or software may be disabled limiting service implementation
Solution Approach 1:
The patent uses Doppler shift measurements of uplink signals as an intermediary mechanism that bypasses UE-dependent positioning hardware and software. Since the measurements are performed on standard cellular uplink signals by base stations rather than relying on UE-based A-GNSS receivers or TDOA measurement capabilities, the system achieves UE-independent positioning that cannot be disabled by user or vendor settings
Solution Approach 2:
The patent replaces UE-dependent positioning mechanisms (A-GNSS receivers, TDOA measurement software) with a base station-based Doppler shift measurement system. This substitution moves the measurement capability from the UE side to the network side, eliminating dependence on UE hardware or software configurations that could be disabled
4Speed
If rapid moving UE connection maintenance is attempted, then handover initiation is required, but connection may be dropped before handover is initiated
Solution Approach 1:
The patent performs preliminary velocity estimation using Doppler shift measurements to predict future UE positions and proactively prepare for upcoming handovers. By knowing the UE's velocity and trajectory in advance, the network can initiate handover procedures before the UE moves out of the current base station's coverage area, preventing connection drops
5Adaptability or versatility
If accurate 2D position and velocity estimation is implemented, then new services like traffic flow prediction are enabled, but existing UE vendors block positioning reporting to cellular operators
Solution Approach 1:
The patent uses Doppler shift measurements as an intermediary to enable accurate velocity and position estimation without requiring A-GNSS positioning reports that UE vendors block. By measuring Doppler shifts directly on cellular uplink signals, the system obtains velocity information that would otherwise require blocked positioning reports, enabling services like traffic flow prediction while bypassing vendor-imposed restrictions
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Provides high-availability and accurate 2D position and velocity estimation with an accuracy of 15 meters (1-sigma) and 1.5 meters/second (1-sigma), respectively, enabling enhanced cellular network functionalities and new use cases like lawful intercept localization and predictive handover management.
Implementation Method 1
The estimation is based on and fully enabled by measurements of Doppler shifts, relative two different antennas of the wireless communication system, of radio signals transmitted from the UE
Data Source
AI summary
A method for kinematic state estimation of a UE in a wireless communication system. The method includes estimating of a kinematic state having two-dimensional position, two-dimensional velocity and a frequency bias of the UE. The estimation is based on and fully enabled by obtained measurements of Doppler shifts, relative two different antennas of the wireless communication system, of radio signals transmitted from the UE, and obtained distance-establishing measurements associated with the UE. A network node performing the method and a computer program therefore are also presented.