Pulse Sequence Optimization for Harmonic-Diversity Exploitation of Time-Modulated Arrays in Cognitive Radio Applications

In this paper, an unconventional time-modulated array (TMA) having its elements controlled by variable gains amplifiers (VGAs) is used as a receiver in a multi-point-to-point communications scenario. Taking advantage from its intrinsic multi-beam radiation features, the TMA is exploited to receive multiple narrowband signals through independent channels. An evolutionary algorithm is employed to define the parameters of the sum-of-weighted-cosine (SWC) pulse sequences aimed at properly shaping the multiple beams while maximizing the signal-to-interference-plus-noise ratio (SINR) at the receiver. A preliminary comparative assessment with classical TMAs using radio-frequency (RF) switches is presented in order to show the potentialities of the proposed approach.