Time Reversal Precoding for Wireless Positioning Accuracy
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Solution Overview
Problem
Current wireless communication systems face challenges in enhancing the detectability of first path signals for positioning due to multipath propagation, particularly in environments with non-line-of-sight (NLOS) conditions, which affects the accuracy of position estimation.
Innovation Solution
The implementation of time-reversal (TR) filtering for positioning signals, where a time-reversal filter is applied to the reference signals based on channel state information (CSI) to enhance the signal-to-noise ratio (SNR) and improve the detection of the line-of-sight (LOS) path, thereby improving positioning accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional transmission methods are used, then system simplicity is maintained, but positioning accuracy deteriorates due to multipath propagation
Solution Approach 1:
The system performs preliminary channel estimation using uplink reference signals before downlink positioning signal transmission. The base station estimates the uplink channel and applies time-reversal precoding in advance, so that when the downlink positioning signals are transmitted, the multipath effects have already been compensated for through the pre-calculated time-reversal filter, improving positioning accuracy without adding complex real-time processing
Solution Approach 2:
The patent uses uplink channel characteristics to create a copy or model of the downlink channel response through time-reversal precoding. By transmitting uplink reference signals and using the received signals to construct a time-reversal filter, the system creates a virtual copy of the optimal transmission path, which is then applied to downlink positioning signals to achieve accurate positioning without directly measuring the downlink channel
2Reliability
If time-reversal filtering is applied, then detection of LOS path is improved, but processing complexity increases
Solution Approach 1:
The system uses the uplink reference signals transmitted by the UE itself to generate the time-reversal filter needed for downlink positioning. The UE's own transmitted signal serves as the basis for creating the channel compensation filter, eliminating the need for separate pilot signals or external calibration processes, thus improving reliability while keeping processing manageable
Solution Approach 2:
The uplink reference signals serve multiple functions: they enable uplink communication, provide channel estimation data for time-reversal precoding, and facilitate downlink positioning signal optimization. This multi-functionality reduces the need for additional dedicated signaling resources and simplifies the overall system architecture while improving LOS path detectability
3Measurement precision
If TR precoding is used for positioning signals, then positioning accuracy is enhanced, but signaling overhead increases
Solution Approach 1:
The patent combines uplink reference signal transmission with downlink positioning signal optimization by using the uplink channel estimates to derive time-reversal precoding for downlink signals. This merging of uplink and downlink functions allows the system to achieve accurate positioning without requiring separate dedicated pilot signals or additional feedback channels, thereby reducing signaling overhead while maintaining high positioning accuracy
Data Source
AI summary
Methods and apparatus for on-demand transmission of time reversal (TR) precoded positioning signals are disclosed. In an example method, a user equipment (UE) may transmit a request for transmission of one or more positioning signals from a base station, the request associated with a TR precoding, transmit one or more signals to the base station, and receive from the base station the one or more positioning signals based at least in part on the transmitted request and the one or more transmitted signals.