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Computation Of Radar Cross Sections Of Complex Targets By Shooting And Bouncing Ray MethodOzgun, Salim 01 September 2009 (has links) (PDF)
In this study, a MATLAB® / code based on the Shooting and Bouncing Ray (SBR)
algorithm is developed to compute the Radar Cross Section (RCS) of complex
targets. SBR is based on ray tracing and combine Geometric Optics (GO) and
Physical Optics (PO) approaches to compute the RCS of arbitrary scatterers. The
presented algorithm is examined in two parts / the first part addresses a new
aperture selection strategy named as &ldquo / conformal aperture&rdquo / , which is proposed and
formulated to increase the performance of the code outside the specular regions,
and the second part is devoted to testing the multiple scattering and shadowing
performance of the code. The conformal aperture approach consists of a
configuration that gathers all rays bouncing back from the target, and calculates
their contribution to RCS. Multiple scattering capability of the algorithm is
verified and tested over simple shapes. Ray tracing part of the code is also used as
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a shadowing algorithm. In the first instance, simple shapes like sphere, plate,
cylinder and polyhedron are used to model simple targets. With primitive shapes,
complex targets can be modeled up to some degree. Later, patch representation is
used to model complex targets accurately. In order to test the whole code over
complex targets, a Computer Aided Design (CAD) format known as Stereo
Lithography (STL) mesh is used. Targets that are composed in CAD tools are
imported in STL mesh format and handled in the code. Different sweep
geometries are defined to compute the RCS of targets with respect to aspect
angles. Complex targets are selected according to their RCS characteristics to test
the code further. In addition to these, results are compared with PO, Method of
Moments (MoM) and Multilevel Fast Multipole Method (MLFMM) results
obtained from the FEKO software. These comparisons enabled us to improve the
code as possible as it is.
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Propagation channel models for 5G mobile networks. Simulation and measurements of 5G propagation channel models for indoor and outdoor environments covering both LOS and NLOS ScenariosManan, Waqas January 2018 (has links)
At present, the current 4G systems provide a universal platform for broadband mobile services; however, mobile traffic is still growing at an unprecedented rate and the need for more sophisticated broadband services is pushing the limits on current standards to provide even tighter integration between wireless technologies and higher speeds. This has led to the need for a new generation of mobile communications: the so-called 5G. Although 5G systems are not expected to penetrate the market until 2020, the evolution towards 5G is widely accepted to be the logical convergence of internet services with existing mobile networking standards leading to the commonly used term “mobile internet” over heterogeneous networks, with several Gbits/s data rate and very high connectivity speeds. Therefore, to support highly increasing traffic capacity and high data rates, the next generation mobile network (5G) should extend the range of frequency spectrum for mobile communication that is yet to be identified by the ITU-R. The mm-wave spectrum is the key enabling feature of the next-generation cellular system, for which the propagation channel models need to be predicted to enhance the design guidance and the practicality of the whole design transceiver system.
The present work addresses the main concepts of the propagation channel behaviour using ray tracing software package for simulation and then results were tested and compared against practical analysis in a real-time environment. The characteristics of Indoor-Indoor (LOS and NLOS), and indoor-outdoor (NLOS) propagations channels are intensively investigated at four different frequencies; 5.8 GHz, 26GHz, 28GHz and 60GHz for vertical polarized directional, omnidirectional and isotropic antennas patterns. The computed data achieved from the 3-D Shooting and Bouncing Ray (SBR) Wireless Insite based on the effect of frequency dependent electrical properties of building materials. Ray tracing technique has been utilized to predict multipath propagation characteristics in mm-wave bands at different propagation environments. Finally, the received signal power and delay spread were computed for outdoor-outdoor complex propagation channel model at 26 GHz, 28 GHz and 60GHz frequencies and results were compared to the theoretical models.
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