Here is Part 3 in the series of articles (Part 1, 2, 3 & 4) continuing the theme concerning 6G and the challenging situations concerning the impact of the changing characteristics of technology advancement that needs constant assessment if evidence from it placed in legal proceedings is to be understood to be trustworthy and reliable.
1. Introduction
Reconfigurable Intelligent Surfaces (RIS) fundamentally alter traditional Cell Site Analysis (CSA) by dynamically controlling electromagnetic wave propagation through reflection, refraction, and focusing. While Cell ID detection remains possible in RIS environments, the forensic interpretation of location data is now significantly more complex.
This document outlines forensic adaptations required to ensure CSA remains legally defensible in 6G networks integrating RIS technology.
2. Key RIS Challenges for Forensic CSA
(A) Multipath Complexity and False Location Inference
- RIS introduces additional, controllable reflections, which may cause multiple signal paths to reach a receiver simultaneously.
- Traditional CSA relies on direct signal paths for location estimation, but RIS can redirect signals from unexpected angles, leading to misinterpretation of a device’s true location.
(B) Time-Varying Signal Paths
- Unlike fixed infrastructure, RIS configurations can change dynamically based on network conditions, traffic demand, or optimization policies.
- RF propagation surveys (RFPS) conducted after an event may not reflect conditions at the time of the incident, making retrospective forensic analysis less reliable.
(C) RIS-Aided Communication Coexistence
- As per ETSI GR RIS-005, forensic challenges arise in two scenarios: Tx-RIS-Rx Paths Only: The signal only reaches the receiver via RIS, meaning the direct transmission path is blocked. Tx-Rx and Tx-RIS-Rx Coexistence: Both direct and RIS-aided paths exist, leading to complex signal interactions.
- In both cases, Cell ID remains detectable, but traditional distance-based analysis (e.g., timing advance calculations) becomes unreliable.
3. Recommended Forensic Adaptations for CSA in RIS Environments
(A) Integrate RIS Control Logs into CSA
Why?
- RIS controllers log all configuration changes that affect signal routing.
- These logs provide crucial metadata on whether a device received a signal directly or via RIS reflection.
Implementation:
- Investigators should request RIS configuration logs from network operators alongside standard 5GC records and CDRs.
- RIS logs should include: Time-stamped beam redirection events. RIS activation/deactivation records. Multipath delay spread values, indicating whether a signal took an indirect path.
(B) Use AI-Based Network State Reconstruction
Why?
- RIS configurations change dynamically, meaning real-time network conditions must be reconstructed for forensic accuracy.
- AI/ML can analyse historical network logs to estimate the most likely RIS-assisted signal paths at a given time.
Implementation:
- Develop machine learning models trained on historical RIS behaviour.
- Use real-time network data to generate forensic “snapshots” of RIS influence at the time of an incident.
(C) Move Beyond CDR-Based Distance Estimations
Why?
- Traditional CSA uses Timing Advance (TA) to estimate device distance, but RIS alters propagation paths, making TA-based analysis unreliable.
- Angle of Arrival (AoA) data must be used instead to determine the actual signal direction.
Implementation:
- Forensic experts must shift from TA-based distance calculations to RIS-aware AoA analysis.
- Request beam-level AoA records from network operators to accurately determine whether a signal came directly from a tower or via an RIS reflection.
(D) Conduct Real-Time Network Testing Instead of RFPS
Why?
- Traditional RF propagation surveys (RFPS) assume fixed coverage areas, which is invalid in RIS environments.
- Real-time network measurements provide a more accurate reflection of signal behaviour at the time of an incident.
Implementation:
- Replace RFPS with active probing tests in RIS-controlled environments.
- Conduct forensic validation by measuring: Direct vs. RIS-assisted path delays. Dynamic RIS reconfigurations affecting specific geographic areas. Network log correlation with real-time RIS behaviour.
4. Legal Implications and Courtroom Readiness
(A) Legal Challenges to RIS-Based CSA Evidence
- Defence attorneys may argue: "Did your forensic analysis account for RIS-assisted signal redirection?" "Can you confirm whether the signal path was direct or manipulated by RIS?" "Did you verify RIS controller logs to determine the actual propagation conditions?"
- Without RIS-aware forensic methods, CSA evidence could be dismissed as unreliable.
(B) Forensic Testimony Adaptations
- CSA experts must be trained in RIS-related forensic principles.
- Prosecutors should require network operators to provide RIS logs alongside standard forensic datasets.
- Courts must establish new evidentiary standards for forensic CSA in RIS-assisted networks.
5. Conclusion
- RIS significantly disrupts traditional CSA methodologies, making Cell ID and timing-based location estimations unreliable.
- Forensic analysts must integrate RIS controller logs, AI-driven network reconstructions, and real-time network testing to maintain CSA accuracy.
- Legal frameworks must evolve to ensure RIS-based CSA remains admissible and scientifically defensible.
This document provides a roadmap for forensic professionals navigating the challenges of RIS in 6G investigations, ensuring accurate, reliable, and court-admissible CSA methodologies.
This article continues on from the discussions posted:
Forensic Challenges in 6G Cell Site Analysis (CSA) and Radio Frequency Propagation Surveys (RFPS) - https://cellsiteanalysis.blogspot.com/2025/04/forensic-challenges-in-6g-cell-site.html
Reconfigurable Intelligent Surfaces (RIS) and forensic implications in 6G CSA (Part 1) - https://cellsiteanalysis.blogspot.com/2025/04/reconfigurable-intelligent-surfaces-ris.html
Cell ID detection in RIS-aided communications (Part 2): 6G Cell Site Analysis (CSA) and Radio Frequency Propagation Surveys (RFPS) - https://cellsiteanalysis.blogspot.com/2025/04/cell-id-detection-in-ris-aided.html
