Concurrent Transmissions (CT) based flooding appears as a highly reliable and low latency mechanism to achieve source-to-sink communication of packets within a Wireless Sensor Network (WSN). CT are usually misunderstood, since they are mainly analyzed in the baseband domain. A comprehensive analysis, including the effects of the carrier, demonstrates that they cannot work in simple phase-modulated communication systems due to the beating effect. In contrast, non-coherent frequency receivers offer a very robust behavior. CT applicability in IEEE 802.15.4 is mainly because of two factors: transmissions are usually demodulated as non-coherent MSK (as opposed to coherent OQPSK) and the Direct Sequence Spread Spectrum (DSSS), that helps minimizing the error rate.

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Although the number of Internet of Things devices increases every year, efforts to decrease hardware energy demands and to improve efficiencies of the energy-harvesting stages have reached an ultra-low power level. However, no current standard of wireless communication protocol (WCP) can fully address those scenarios. Our focus in this paper is to introduce treNch, a novel WCP implementing the cross-layer principle to use the power input for adapting its operation in a dynamic manner that goes from pure best-effort to nearly real time. Together with the energy-management algorithm, it operates with asynchronous transmissions, synchronous and optional receptions, short frame sizes and a light architecture that gives control to the nodes. These features make treNch an optimal option for wireless sensor networks with ultra-low power demands and severe energy fluctuations. We demonstrate through a comparison with different modes of Bluetooth Low Energy (BLE) a decrease of the power consumption in 1 to 2 orders of magnitude for different scenarios at equal quality of service. Moreover, we propose some security optimizations, such as shorter over-the-air counters, to reduce the packet overhead without decreasing the security level. Finally, we discuss other features aside of the energy needs, such as latency, reliability or topology, brought again against BLE.

Hardware Security Modules (HSM) serve as a hardware based root of trust that offers physical protection while adding a new security layer in the system architecture. When combined with decentralized access technologies as Blockchain, HSM offers robustness and complete reliability enabling secured end-to-end mechanisms for authenticity, authorization and integrity. This work proposes an efficient integration of HSM and Blockchain technologies focusing on, mainly, public-key cryptography algorithms and standards, that result crucial in order to achieve a successful combination of the mentioned technologies to improve the overall security in Industrial IoT systems. To prove the suitability of the proposal and the interaction of an IoT node and a Blockchain network using HSM a proof of concept is developed. Results of time performance analysis of the prototype reveal how promising the combination of HSMs in Blockchain environments is.