Biblio

Acoustic communication is a key enabler for underwater Internet of Things networks between autonomous underwater platforms. Underwater Internet of Things networks face a harsh communications environment and limited energy resources which makes them susceptible to interference, whether intentional (i.e., jamming) or unintentional. Resilient, power efficient waveforms and modulation schemes are needed for underwater acoustic communications in order to avoid outages and excessive power drain. We explore the impact of modulation scheme on the resiliency of underwater acoustic communications in the presence of channel impairments, interference, and jamming. In particular, we consider BFSK and OFDM schemes for underwater acoustic communications and assess the utility of Polar coding for strengthening resiliency.

Key management is critical for the successful operation of a cryptographic system in wireless networks. Systems based on asymmetric keys require a dedicated infrastructure for key management and authentication which may not be practical for ad-hoc Underwater Acoustic Networks (UANs). In symmetric-key systems, key distribution is not easy to handle when new nodes join the network. In addition, when a key is compromised all nodes that use the same key are not secure anymore. Hence, it is desirable to have a dynamic way to generate new keys without relying on past keys. Physical Layer Security (PLS) uses correlated channel measurements between two underwater nodes to generate a cryptographic key without exchanging the key itself. In this study, we set up a network of two legitimate nodes and one eavesdropper operating in a shallow area off the coast of Portugal. We propose novel features based on the Channel Impulse Response (CIR) of the established acoustic link that could be used as an initial seed for a crypto-key generation algorithm. Our results show that the two nodes can independently generate 306 quantization bits after exchanging 187 probe signals. Furthermore, the eavesdropper fails to generate the same bits from her/his data even if she/he performs exactly the same signal processing steps of the legitimate nodes.