RIS-Aided UE Passive RF Sensing Around Signal Blockages
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Solution Overview
Problem
Existing RF sensing techniques face challenges in determining the position of an object due to blockages that prevent the receipt of RF signals by receiving devices in wireless communication networks.
Innovation Solution
Utilizing a Reconfigurable Intelligent Surface (RIS) to redirect RF signals, allowing for the determination of an object's position by comparing the time of arrival of line-of-sight and echo signals reflected by the RIS, leveraging time difference measurements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If RF sensing techniques are used to determine object position, then positioning capability is provided, but blockages prevent receipt of RF signals by receiving devices
Solution Approach 1:
A reconfigurable intelligent surface (RIS) is introduced as an intermediary component to reflect RF signals from base stations to receiving devices. The RIS acts as a mediator that creates alternative signal paths around blockages, enabling reliable signal receipt without requiring direct line-of-sight between transmitters and receivers.
2Ease of operation
If direct RF signal transmission is used, then simple transmission path is maintained, but blockages prevent signal receipt
Solution Approach 1:
The RIS serves as a controllable intermediary that maintains operational simplicity while improving reliability. Although it adds a reflection component, the system remains easy to operate through centralized control of the RIS elements, which can be dynamically configured to provide reliable signal paths without complex manual intervention.
Solution Approach 2:
The RIS provides dynamic adaptability by adjusting the phase and amplitude of reflected signals in real-time. This dynamic configuration allows the system to adapt to changing environmental conditions and blockages, maintaining reliable signal receipt while preserving operational simplicity through automated control.
3Reliability
If RIS is introduced to redirect signals, then signal blockage is overcome, but device complexity increases
Solution Approach 1:
The RIS is designed as a planar array of passive or low-power active elements that can be controlled through software. This intermediary structure overcomes blockages by providing controllable signal reflection paths while maintaining relatively simple device architecture compared to active relay systems, reducing overall system complexity.
Solution Approach 2:
The RIS replaces complex mechanical signal routing systems with an electronically controlled reflective surface. By using phase shifters and amplitude controllers in a planar array, the system achieves dynamic signal steering without mechanical moving parts, thereby overcoming blockages while minimizing device complexity.
4Measurement precision
If time difference measurement is used for positioning, then positioning precision is improved, but measurement accuracy may be affected by signal blockages
Solution Approach 1:
The RIS ensures that both the direct signal and the reflected signal from the target object can be reliably received by providing controlled reflection paths. This intermediary enables accurate time difference measurements by ensuring that signals used for positioning are not blocked, thereby maintaining both precision and reliability in object localization.
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
Enables accurate positioning of objects by overcoming signal blockages, enhancing the reliability and precision of RF sensing in wireless communication systems.
Implementation Method 1
configuring the RIS to reflect a line-of-sight (LOS) wireless signal toward the receiving device
Data Source
AI summary
Techniques are disclosed for determining an object's location by using a Reconfigurable Intelligent Surface (RIS) to aid in RF sensing. Radar techniques can be used in which one or more base stations act as a transmitter and a receiving device acts as a receiver in a bistatic or multi-static radar configuration where an RIS directs signals transmitted by the one or more base stations to the receiving device. By comparing the time a line-of-sight (LOS) signal (redirected to the receiving device by the RIS) is received by the receiving device with that of an echo signal (redirected to the receiving device by the RIS) from a reflection of an RF signal from the object, a position of the object can be determined. Depending on desired functionality, this position can be determined by the receiving device or by a location server or other network entity.