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In this paper, the performance of a universal mobile telecommunication system (UMTS)-based passive multistatic radar in a line-of-sight (LoS) environment is studied. The presence of LoS component from the target considerably alters the received signal model, therefore, its characterization is necessary and is the main subject of this work where the transceivers and a target are localized in a three-dimensional Euclidean space. The probability density function (PDF) of the received signal in the presence of LoS is derived and the closed-form expressions of the modified Cramer-Rao lower bounds (MCRLBs) on the Euclidean coordinates of target's position and velocity are found. It is shown that modified Fisher information matrix (MFIM) is a combination of MFIMs due to non-LoS (NLoS) components and LoS component. With the aid of numerical examples, it is verified that by exploiting LoS, the target radar cross section (RCS) increases, which improves the accuracy of target's detection and parameter estimation. In addition, it is also shown that by exploiting LoS component, the performance limits of a waveform can be determined for a generalized radar cross section model (GRCSM), which provides the characterization of a waveform for a broader range of radar applications.

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Lie's linearizability criteria for scalar second-order ordinary differential equations had been extended to systems of second-order ordinary differential equations by using geometric methods. These methods not only yield the linearizing transformations but also the solutions of the nonlinear equations. Here, complex methods for a scalar ordinary differential equation are used for linearizing systems of two second-order ordinary and partial differential equations, which can use the power of the geometric method for writing the solutions. Illustrative examples of mechanical systems including the LaneEmden type equations which have roots in the study of stellar structures are presented and discussed.

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