RIS Scheduling for Accurate Sidelink PRS Positioning
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Solution Overview
Problem
Existing wireless communication systems face challenges in accurately measuring positioning reference signals (PRS) due to interference and signal reflection, which hampers precise positioning in 5G networks, particularly in vehicle-to-everything (V2X) communication technologies for autonomous driving applications.
Innovation Solution
The implementation of reconfigurable intelligent surfaces (RIS) that can be controlled to switch between enabled and disabled states, allowing for precise measurement of PRS signals by adjusting their reflective properties, enabling accurate time-of-arrival measurements through controlled signal paths.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If reconfigurable intelligent surfaces are always enabled to provide signal reflection, then coverage and signal availability are improved, but measurement precision of direct paths deteriorates due to interference between direct and reflective paths
Solution Approach 1:
The RIS is configured to alternately switch between enabled and disabled states in a periodic manner. During enabled states, the RIS provides reflective paths for coverage enhancement. During disabled states, only direct paths are available for accurate measurement. This periodic switching allows the system to collect both coverage data and precise measurement data at different time instances.
Solution Approach 2:
The system performs measurements during predetermined time intervals when the RIS is scheduled to be in specific states. The UE is configured to measure PRS signals during both enabled and disabled states of the RIS, allowing preliminary collection of measurement data before final positioning calculations are performed.
2Measurement precision
If reconfigurable intelligent surfaces are always disabled to avoid interference, then measurement precision of direct paths is improved, but coverage and signal availability deteriorate
Solution Approach 1:
The RIS operates in periodic cycles alternating between enabled and disabled states. During disabled states, measurement precision is maximized for direct path measurements. During enabled states, signal availability and coverage are enhanced through reflective paths. This periodic operation ensures both measurement accuracy and signal reliability are achieved at different times.
Solution Approach 2:
The measurement process is segmented into different time intervals corresponding to different RIS states. The system separates measurement operations into phases where direct path measurements are performed during disabled states and coverage enhancement is utilized during enabled states, allowing each function to operate optimally without interference.
3Measurement precision
If reconfigurable intelligent surfaces switch states frequently to provide both direct and reflective path measurements, then positioning precision is improved, but device complexity increases
Solution Approach 1:
The RIS follows a periodic switching pattern with predetermined periods for enabled and disabled states. This regular periodic operation simplifies the control logic compared to arbitrary frequent switching, as the system can anticipate state transitions based on the established period, reducing control complexity while maintaining the ability to provide both measurement types.
Solution Approach 2:
The system uses feedback mechanisms where the UE reports measurement results from both direct and reflective paths, and the location server processes this information to determine accurate position. The feedback loop allows the system to achieve high positioning precision through coordinated switching and measurement reporting without requiring overly complex real-time control of the RIS states.
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
Enhances the accuracy of PRS measurements by distinguishing direct and reflective paths, improving positioning precision in 5G networks and supporting advanced V2X communication for autonomous driving.
Implementation Method 1
reconfigurable intelligent surfaces (RIS) that can be controlled to switch between enabled and disabled states, allowing for precise measurement of PRS signals by adjusting their reflective properties
Data Source
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Figure 2B
AI summary
In an aspect, a user equipment (UE) may control one or more reconfigurable intelligent surfaces (RIS) in accordance with one or more RIS schedules that indicate times when the one or more RIS are in an enabled state and times when the one or more RIS are in a disabled state. The UE may request at least one participating UE of one or more participating UEs to transmit at least one positioning reference signal (PRS) in a PRS resource. The UE may measure the at least one PRS from the at least one participating UE in accordance with the RIS schedule to make one or more measurements of the at least one PRS when the one or more RIS are in the disabled state and to make one or more measurements of the at least one PRS when the one or more RIS are in the enabled state.