Bistatic RF Sensing Using Uplink-Downlink Doppler Cancellation
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Solution Overview
Problem
Existing wireless communication networks face challenges in integrating RF sensing capabilities without significant additional costs, particularly due to issues related to oscillator offset and UE mobility.
Innovation Solution
The implementation of bistatic or multi-static sensing using both uplink and downlink signals to facilitate cancellation of signal components and improve accuracy, utilizing UE and base station measurements to compute target position and velocity estimates.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If RF sensing is implemented using existing wireless communication nodes (base stations and user equipment), then additional infrastructure costs are avoided, but measurement precision deteriorates due to oscillator offset and UE mobility effects
Solution Approach 1:
The patent introduces a sensing server as an intermediary that collects measurements from multiple base stations and user equipment, processes the data, and computes target position and velocity. This mediator handles the complex calculations and error corrections centrally, allowing individual nodes to use inexpensive oscillators while maintaining overall measurement precision through coordinated processing.
Solution Approach 2:
The system implements feedback mechanisms where the sensing server processes measurements from multiple nodes and provides corrected position and velocity estimates. The system uses feedback loops to compensate for oscillator offsets by comparing measurements across multiple base stations and UEs, and adjusts calculations to account for UE mobility based on reported measurements and known node positions.
2Device complexity
If downlink signals alone are used for sensing, then system complexity is reduced, but measurement precision deteriorates due to uncancelled oscillator offset and Doppler effects
Solution Approach 1:
The patent merges downlink and uplink signal measurements into a unified sensing approach. Base stations transmit downlink signals that reflect off targets and are received by UEs, while UEs transmit uplink signals that reflect off targets and are received by base stations. By combining measurements from both directions, the system cancels oscillator offset effects and isolates target velocity through Doppler analysis, achieving higher precision without significantly increasing system complexity.
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 reduces errors from oscillator offset and UE mobility, enabling accurate RF sensing without additional infrastructure costs, by leveraging existing wireless communication networks.
Implementation Method 1
the UE measured frequency offset comprising a Doppler shift component corresponding to a velocity of the target
Data Source
AI summary
A technique is performed at a user equipment (UE) for supporting one or more radio frequency (RF) sensing measurements. A reflected downlink signal is received, wherein the reflected downlink signal is transmitted as a downlink signal from a base station and reflected off of a target. An uplink signal is transmitted to be reflected off of the target and received by the base station as a reflected uplink signal. A UE receive-transmit (RX-TX) time difference is determined, representing a difference between a time at which the reflected downlink signal is received by the UE and a time at which the uplink signal is transmitted by the UE. A UE measured frequency offset is determined based on reception of the reflected downlink signal, the UE measured frequency offset comprising a Doppler shift component corresponding to a velocity of the target.