Biblio
In this work, the algorithm of increasing the information security of a communication system with Orthogonal Frequency Division Multiplexing (OFDM) was achieved by using a discrete-nonlinear Duffing system with dynamic chaos. The main idea of increasing information security is based on scrambling input information on three levels. The first one is mixing up data order, the second is scrambling data values and the final is mixing symbols at the Quadrature Amplitude Modulation (QAM) plot constellation. Each level's activities were made with the use of pseudorandom numbers set, generated by the discrete-nonlinear Duffing system with dynamic chaos.
In this paper, the use of some of the most popular adaptive filtering algorithms for the purpose of linearizing power amplifiers by the well-known digital predistortion (DPD) technique is investigated. First, an introduction to the problem of power amplifier linearization is given, followed by a discussion of the model used for this purpose. Next, a variety of adaptive algorithms are used to construct the digital predistorter function for a highly nonlinear power amplifier and their performance is comparatively analyzed. Based on the simulations presented in this paper, conclusions regarding the choice of algorithm are derived.