Biblio

In-Band Full-Duplex (IBFD) Underwater Acoustic (UWA) communication technology plays a major role in enhancing the performance of Underwater acoustic sensor networks (UWSN). Self-Interference (SI) is one of the main inherent challenges affecting the performance of IBFD UWA communication. To reconstruct the SI signal and counteract the SI effect, this is important to estimate the short range channel through which the SI signal passes. Inaccurate estimation will result in the performance degradation of IBFD UWA communication. From the perspective of engineering implementation, we consider that the UWA communication modem shell has a significant influence on the short-range SI channel, which will limit the efficiency of self-interference cancellation in the analog domain to some degree. Therefore we utilize a simplified model to simulate the influence of the structure of the IBFD UWA communication modem on the receiving end. This paper studies the effect of acoustic-shell coupling on near-end self-interference signal of IBFD UWA communication modem. Some suggestions on the design of shell structure of IBFD UWA communication modem are given.

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.