Polynomial-phase signals (PPS) appear in a variety of applications and several algorithms are available to estimate their parameters in the presence of noise. Among the available tools, the product high order ambiguity function (PHAF) has the merit of performing well in the presence of a superposition of PPS's. In this work, we generalize the PHAF to handle two-dimensional PPS's. Then we show an example of application motivating such an extension: the high resolution imaging of moving targets from synthetic aperture radars (SAR). Using the 2D-PHAF, we will propose an algorithm that compensates jointly for the range cell migration and the phase modulation induced by the relative radar-target motion in order to produce a focused image of the moving target. Numerical results illustrate the advantages of the proposed method when compared to existing auto-focusing algorithm
Femtocells are receiving considerable interest in mobile communications as a strategy to overcome the indoor coverage problems as well as to improve the efficiency of current macrocell systems. One of the most critical issues in femtocells is the potential interference between nearby femtocells and from femtocells to macrocells or to mobile handsets. In this work, we illustrate some decentralized strategies for an OFDMA femtocell system, based on game theory, where non-cooperative femtocells self-organize in order to find out the most appropriate access strategy, considering the decision phase and radio access jointly. The strategies illustrated in this work fall within the context of the FREEDOM European Project
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