Chaotic signals are used in digital communications primarily in a bid to increase the security of transmissions. Moreover, second-order cyclostationary characteristics can easily be identified in chaotic signals used in communication systems. The detection of the cyclostationary properties in the transmitted signal decreases the security level for such systems. In this paper, we focus our attention on the eradication of cyclostationary properties present in chaotic signals, and to that end, we introduce a new method based on symbol period randomization to eliminate the spectral lines corresponding to the multiples of the baud rates. Finally, we compare our proposed method with another existing method in order to show the efficiency of ours in eliminating the cyclostationary properties.

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This paper investigates the problem of communication relay between ground units using an unmanned aerial vehicle (UAV). The positions of the ground units are considered to be unavailable to the UAV and the objective is to drive the vehicle in real-time to the optimal placement maximizing the strength of communication signals from ground units. To this end, a novel non model-based navigation law is proposed that is solely based on signals strength and their angles of arrival. The stability of the proposed navigation law is proved in two scenarios, driving the UAV to the optimal placement and returning it back to the launch base. Simulation and experimental results are given to show the effectiveness of the proposed approach.

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