Beamforming Positioning Reference Signals for NLoS Localization
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Solution Overview
Problem
Current wireless communication networks face challenges in accurately localizing user equipment (UE) in multipath channel environments due to multipath propagation and non-line-of-sight (NLoS) errors, which affect the accuracy of time of arrival (TOA) estimates and relative signal timing differences (RSTD) measurements.
Innovation Solution
The implementation of beamforming positioning reference signals (PRS) using a massive array antenna to concentrate signal energy into directional beam cones, allowing for accurate TOA estimation even in NLoS environments by exploiting the geometrical relationship of path components, and using parameters like angle of departure (AoD) and angle of arrival (AoA) to distinguish individual path components in both space and time domains.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional omnidirectional PRS transmission is used, then cell coverage is provided, but positioning accuracy deteriorates in multipath/NLoS environments
Solution Approach 1:
The omnidirectional PRS transmission is segmented into multiple directional beam cones using a massive array antenna. Each beam cone transmits PRS signals in specific spatial directions, allowing the system to distinguish between line-of-sight paths and multipath components based on their spatial origin, thereby improving positioning accuracy in NLoS environments.
Solution Approach 2:
The patent introduces the spatial dimension by transmitting PRS signals through multiple beam cones with different orientation parameters (azimuth and elevation angles). This adds a spatial dimension to the traditional time-based TOA measurements, enabling the system to resolve ambiguities in multipath environments and achieve accurate positioning even when direct LoS paths are unavailable.
2Measurement precision
If multiple base stations are used for positioning, then positioning accuracy is improved, but device complexity increases
Solution Approach 1:
The massive array antenna at each base station is configured to transmit multiple beam cones simultaneously, making each base station capable of providing positioning information for multiple spatial directions. This multi-functionality allows a single base station to contribute to accurate positioning without requiring multiple separate base stations, thereby reducing system complexity while maintaining positioning accuracy.
3Measurement precision
If signal energy is transmitted omnidirectionally, then all users in cell are covered, but signal energy concentration for positioning deteriorates
Solution Approach 1:
Instead of uniform omnidirectional transmission, the system applies local quality by concentrating signal energy into specific beam cones directed toward particular spatial regions. Each beam cone provides enhanced signal energy concentration for users in its coverage direction, enabling accurate TOA measurements while the overall system maintains coverage through multiple beam cones pointing to different locations.
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
This approach enables reliable and accurate UE localization in both LoS and NLoS channel environments, reducing the number of base stations required for position estimation and improving positioning accuracy by focusing signal energy and using path-dependent parameters for precise location calculation.
Implementation Method 1
The implementation of beamforming positioning reference signals (PRS) using a massive array antenna to concentrate signal energy into directional beam cones
Implementation Method 2
multipath propagation and non-line-of-sight (NLoS) errors, which affect the accuracy of time of arrival (TOA) estimates
Implementation Method 3
accurate TOA estimation even in NLoS environments by exploiting the geometrical relationship of path components
Data Source
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AI summary
A receiver (UE), which is located in a spatial region of interest (1 18) served by a transmitter (eNB1-eNB3) of a wireless communication network, receives a radio signal from at least one transmitter (eNB1-eNB3) of the wireless communication network, and the radio signal has a plurality of position reference signal (PRS) sequences. Each PRS sequence has associated therewith a different PRS sequence identifier, and each PRS sequence is send using a different beam cone (116) of the transmitter (eNB1-eNB3). The beam cones (116) of the transmitter (eNB1-eNB3) for sending the plurality of PRS sequences are directed to the spatial region of interest (118). The receiver (UE) processes the radio signal to estimate a time of arrival (TOA) of each PRS sequence and to obtain for each PRS sequence the associated PRS sequence identifier. A position of the receiver (UE) is estimated using the times of arrival and the obtained PRS sequence identifiers.