The purpose of this article is to present three theses – (1) a cultural one: cyberspace is an advanced technical and cultural creation – it is an embodiment of dreams of numerous creators, inventors and engineers; (2) a technical one: security and cyberspace are inseparable components (hence cybersecurity); (3) and a paranoid one: complete security, if achievable, is not a permanent state (hence cyber(in)security). Cyberspace is conceived as a set of digital techniques used to exchange information but also as a new type of social space, partially virtual, which may constitute a being entirely separated from a physical one. A pivotal date for arising of cyberspace may be considered the year 1968 in which routing in the ARPANET network appeared and so did the first programmable logical controller (PLC). For cyberspace this will be the year 1976 – publishing of the key agreement protocol by Witfield Diffie and Martin Hellman. Development of security is correlated with warfare and armament – the military sector has historically made the most significant investments in this area.
For many adaptive noise control systems the Filtered-Reference LMS, known as the FXLMS algorithm is used to update parameters of the control filter. Appropriate adjustment of the step size is then important to guarantee convergence of the algorithm, obtain small excess mean square error, and react with required rate to variation of plant properties or noise nonstationarity. There are several recipes presented in the literature, theoretically derived or of heuristic origin.
This paper focuses on a modification of the FXLMS algorithm, were convergence is guaranteed by changing sign of the algorithm steps size, instead of using a model of the secondary path. A TakagiSugeno-Kang fuzzy inference system is proposed to evaluate both the sign and the magnitude of the step size. Simulation experiments are presented to validate the algorithm and compare it to the classical FXLMS algorithm in terms of convergence and noise reduction.