The adoption of wireless communications and, in particular, Wi-Fi, at the lowest level of the factory automation hierarchy has not increased as fast as expected so far, mainly because of serious issues concerning determinism. Actually, besides the random access scheme, disturbance and interference prevent reliable communication over the air and, as a matter of fact, make wireless networks unable to support distributed real-time control applications properly. Several papers recently appeared in the literature suggest that diversity could be leveraged to overcome this limitation effectively. In this paper a reference architecture is introduced, which describes how seamless link-level redundancy can be applied to Wi-Fi. The framework is general enough to serve as a basis for future protocol enhancements, and also includes two optimizations aimed at improving the quality of wireless communication by avoiding unnecessary replicated transmissions. Some relevant solutions have been analyzed by means of a thorough simulation campaign, in order to highlight their benefits when compared to conventional Wi-Fi. Results show that both packet losses and network latencies improve noticeably.

THIS PREPRINT IS NOW ISSUED AS IEEE ACCESS https://ieeexplore.ieee.org/document/10231329 The CENELEC TS 50701 is the first encompassing standard aiming at  governing cybersecurity risk management processes within the railway  industry. Although the technical maturity of this framework is  undeniable, its application in practical projects is still an active  field of discussion among practitioners, especially when dealing the  communication-heavy subsystems. Among such subsystems, signaling is  among the most critical ones. Both Communication-based Train Control  (CBTC) and European Railway Traffic Management Systems (ERTMS) heavily  rely on wireless communications for their operation. This paper  describes two cybersecurity attack scenarios regarding wireless  communications for CBTCs that can impact the safety of these systems  using the lens of the framework provided by the novel CENELEC TS 50701.  In doing so, we discuss the implications of using such guidance,  especially concerning the different interpretations found in the  literature regarding zoning communication systems, to assess and  mitigate the cybersecurity risk and improve the posture of CBTC systems  concerning the examined attacks. Experimental tests conducted in  controlled laboratory environments and high fidelity simulations have  been conducted to support the cybersecurity analysis.

The paper addresses the problem of time offset synchronization in the presence of temperature variations, which lead to a non-Gaussian environment. In this context, regular Kalman filtering reveals to be suboptimal. A functional optimization approach is developed in order to approximate optimal estimation of the clock offset between master and slave. A numerical approximation is provided to this aim, based on regular neural network training. Other heuristics are provided as well, based on spline regression. An extensive performance evaluation highlights the benefits of the proposed techniques, which can be easily generalized to several clock synchronization protocols and operating environments.