Wavelet-Based CSI Reconstruction for Improved Wireless Security Through Channel Reciprocity

TL;DR

This work experimentally scrutinizes channel reciprocity for resource-constrained IoT devices and reveals significant degradation under practical conditions. It introduces a Wavelet Transform-based CSI reconstruction framework that uses wavelet coherence and time-lagged cross-correlation to align reciprocal channel content, achieving substantial reciprocity improvements. Building on this, it proposes the Wavelet-based Secret Key Generation (WSKG) scheme, which demonstrates higher key-generation rates and lower error rates across realistic scenarios, including asynchronous measurements and packet losses. Additionally, the authors propose a CSI-driven authentication handshake that leverages temporal CSI variation to robustly detect replay attacks, offering practical, hardware-conscious security enhancements for IoT networks.

Abstract

The reciprocity of channel state information (CSI) collected by two devices communicating over a wireless channel has been leveraged to provide security solutions to resource-limited IoT devices. Despite the extensive research that has been done on this topic, much of the focus has been on theoretical and simulation analysis. However, these security solutions face key implementation challenges, mostly pertaining to limitations of IoT hardware and variations of channel conditions, limiting their practical adoption. To address this research gap, we revisit the channel reciprocity assumption from an experimental standpoint using resource-constrained devices. Our experimental study reveals a significant degradation in channel reciprocity for low-cost devices due to the varying channel conditions. Through experimental investigations, we first identify key practical causes for the degraded channel reciprocity. We then propose a new wavelet-based CSI reconstruction technique using wavelet coherence and time-lagged cross-correlation to construct CSI data that are consistent between the two participating devices, resulting in significant improvement in channel reciprocity. Additionally, we propose a secret-key generation scheme that exploits the wavelet-based CSI reconstruction, yielding significant increase in the key generation rates. Finally, we propose a technique that exploits CSI temporal variations to enhance device authentication resiliency through effective detection of replay attacks.

Figures (25)

• Figure 1: Experiment setup.
• Figure 2: Power spectrum of CSI at AP and STA: LoS-ShortRange scenario.
• Figure 3: Channel reciprocity assessment metrics.
• Figure 4: Key generation performance metrics.
• Figure 5: Impact of location on WC under raw CSI.