Multi-bit Secret Key Generation for LoRaWAN based 6G mMTC using Autoencoders

Long Range Wide Area Network (LoRaWAN) is a promising technology for enabling 6G massive Machine Type Communication (mMTC). However, it lacks in terms of key management schemes (e.g. key updates). We therefore propose the usage of Physical Layer Security (PLS) based Secret Key Generation (SKG) within LoRaWANs in this work in order to establish efficient session key management. Further, we introduce the utilization of Autoencoders (AEs) for Reciprocity Enhancement (RE) in order to optimize the SKG performance and study the impact of multi-bit quantization. To assess the effectiveness of our proposed approach, we conducted experiments using an experimental testbed. The obtained results highlight the potential benefits of AE based key management and multi-bit quantization for LoRaWAN in terms of improved Bit Disagreement Rate (BDR) and Key Generation Rate (KGR) utilizing Received Signal Strength Indicator (RSSI) measurements and respective preprocessing.