RIS-Aided UE RTT Positioning via Phase-Shifted Reflections
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Solution Overview
Problem
Current wireless positioning technologies face challenges in accurately determining the location of user equipment (UE) due to limitations in timing synchronization and the inability to differentiate reflections from reconfigurable intelligent surfaces (RIS) from other environmental reflections, especially for low-tier UEs and in scenarios with obstacles.
Innovation Solution
The method involves using a reconfigurable intelligent surface (RIS) to aid in UE-based round-trip-time (RTT) positioning by transmitting an uplink reference signal, receiving its reflection, and calculating the distance based on transmission-to-reception time differences, with assistance data providing necessary parameters for accurate signal identification and processing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional wireless positioning methods are used, then positioning can be performed, but accuracy is insufficient due to inability to differentiate RIS reflections from environmental reflections
Solution Approach 1:
The patent introduces an intermediary identification mechanism where the RIS embeds its identity information (RIS ID) into the reflected signal through phase shifting patterns. This intermediary marker allows the UE to distinguish RIS-reflected signals from environmental reflections, resolving the signal identification problem and improving positioning accuracy.
Solution Approach 2:
The patent applies the concept of 'color changes' by modifying the phase characteristics of the reflected signal based on the RIS ID. Different RIS configurations produce distinct phase patterns, enabling the UE to identify and differentiate between reflections from different RIS units, thereby improving measurement precision.
2Productivity
If UE-based RTT positioning is implemented, then positioning functionality is provided, but power consumption is high for low-tier UEs
Solution Approach 1:
The patent implements partial action by having the UE perform only essential RTT measurements with reduced processing complexity. The UE measures the round-trip time of signals reflected from RIS without requiring full-featured positioning processing, thereby achieving acceptable positioning efficiency while significantly reducing power consumption for low-tier UEs.
Solution Approach 2:
The RIS performs self-service by actively managing the reflection process and embedding identification information, reducing the processing burden on the UE. The UE simply needs to detect the phase patterns and measure time differences, rather than performing complex signal analysis, thus lowering power consumption while maintaining positioning efficiency.
3Area of stationary object
If RIS reflections are utilized for positioning, then coverage is improved, but timing synchronization becomes more challenging
Solution Approach 1:
The patent applies preliminary action by having the network pre-configure the RIS with specific phase shifting patterns corresponding to different RIS IDs before the positioning process. This pre-configuration allows the UE to immediately identify and synchronize with the correct RIS reflection without complex real-time synchronization challenges, extending coverage while maintaining timing accuracy.
Solution Approach 2:
The patent implements feedback mechanisms where the network receives measurement reports from the UE and adjusts timing synchronization parameters accordingly. The network can compensate for timing variations introduced by RIS reflections through feedback-based synchronization adjustments, thereby maintaining measurement precision while extending positioning coverage.
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 enhances the accuracy and efficiency of UE-based RTT positioning by reducing power consumption and latency, improving coverage, and enabling precise location determination even in challenging environments.
Implementation Method 1
receiving, from the first RIS, a reflection of the uplink reference signal
Data Source
AI summary
Disclosed are techniques for wireless positioning. In an aspect, a user equipment (UE) transmits an uplink reference signal towards a first reconfigurable intelligent surface (RIS) associated with at least one base station, receives, from the first RIS, a reflection of the uplink reference signal, wherein at least one transmission parameter of the reflection identifies the reflection as the reflection of the uplink reference signal, and enables a distance between the UE and the first RIS to be calculated based, at least in part, on a transmission-to-reception (Tx-Rx) time difference measurement for the UE, the Tx-Rx time difference measurement representing a difference between a transmission time from the UE of the uplink reference signal to the first RIS and a reception time at the UE of the reflection of the uplink reference signal from the first RIS.