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3058 Wireless Links and Propagation
8th Semester ECE
ECTS : 6
Study Load : theory 3, lab 2
Language : el
Learning Outcomes : This course provides the student with the
necessary knowledge in the broad field of Wireless Links and Propagation
of E/M waves.
Regarding Wireless Links, (i) the
propagation losses in LOS
and NLOS channels are studied, (ii) the
fading in wireless channels characterized by either
multipath propagation or by time variability is analyzed in detail, (iii) the models of narrow and
wideband fading are studied, (iv) the factors and mechanisms
that affect the transmission of digital signals in fading channels as well as
the related impacts are examined and (v) the
techniques for dealing with fading are analyzed. Regarding the propagation of electromagnetic waves, the course content includes (i) an analysis of basic knowledge on the propagation of electromagnetic waves, (ii) a study of the basic mechanisms of reflection, refraction and diffraction of electromagnetic waves, and (iii) the application of propagation models in various environments for the main types of wireless links. In particular, the student acquires knowledge in the following sub-topics: Propagation loss models in LOS and NLOS channels, multipath propagation and delay dispersion, Doppler effect and frequency dispersion, performance of wireless systems in fading channels, fading management techniques such as adaptive transmission, power control and differential protection. Propagation in free and non-free space, propagation in the atmosphere, reflection,
diffraction, Fresnel zones, diffraction and losses from multiple
obstacles, two-beam model, tropospheric scattering, scattering from near-ground links, near-ground propagation models.
Finally, in the context of laboratory exercises, through practice in
the specialized ICS telecomm radio coverage software, the
student is trained in practical radio coverage problems.
Supplementary topics of antenna and antenna array technology. Finding current along linear antennas: Hallen and Pocklington integral equations and their solution by Moment Methods. Correlation of antenna input impedance with wireless link parameters. Propagation in the terrestrial environment. Oblique incidence, Fresnel theory, Brewster angle. Effect of ground curvature and irregularities. Elevated antennas, optical horizon. Tropospheric waves. Propagation of electromagnetic waves in the troposphere. Effect of the propagation medium. Diffraction, scattering from ground obstacles, Fresnel zones, diffraction losses, multiple obstacles. Two-beam model. Tropospheric scattering, scattering in links near the ground. Power calculations in wireless links. Effect of precipitation on microwave frequencies. Near-ground transmission models. Indoor propagation models. Large-scale transmission losses. Fading in wireless channels. Digital modulation techniques. Coding techniques for transmission error correction. Fading control techniques. Multiple access schemes and interference issues. Channel and system capacity.
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