Wireless and Satellite Communications

Objective

The objective of the course is a comprehensive presentation of the analysis and design techniques of wireless and satellite communication links. The course includes two sections. In the first section we attempt a review of fundamental concepts of antenna technology and electromagnetic propagation. An analytic description of propagation aspects in current wireless communication systems is given for the mostly used frequency bands. Propagation mechanisms and prediction models are provided for successful design of fixed wireless access systems. We analyze international standards and recommendations (ITU-R) for the efficient design of wireless links providing the critical metrics and quality parameters. The section closes with the analysis of antenna arrays, the methods used for array signal processing and typical applications of optimum beam formers. The second section deals with the review of Satellite communications networks technology providing the current state of structural blocks of these networks, discussing the multiple access techniques and network topologies used. Typical examples are given for VSAT networks and the design of satellite links.

Course Contents

• Electromagnetic waves and wave polarization. Antennas as radiators and several antenna types. Antenna parameters, radiation patterns, directive gain, power gain, effective aperture, effective length.
• Electromagnetic wave propagation mechanisms: Reflection and refraction, propagation in the troposphere.
• Electromagnetic wave propagation mechanisms: Scattering, diffraction, propagation models. Quality parameters for effective link design.
• Analysis of antenna arrays. Types, topologies, geometry of arrays. Fundamental parameters for antenna array system representation. Narrowband assumption. Basic structures for beamforming.
• Array signal processing. Uniform linear arrays. Visible region, antenna array weighting-feeding. Radiation patterns parameters and beamsteering.
• Statistical antenna array signal processing. Narrowband processing, conventional beam former, null steering beam former. Wiener filters and digital beamforming techniques for optimum beam formers.
• The development of satellite communication networks. Review of services. Geometrical parameters and orbits (GEO, LEO, MEO, HEO). Satellite transponders and basic structures. Antennas on board the satellite.
• Noise in satellite communications (antennas and receivers). Receiver architectures. Non-linearities in satellite high power amplifiers. Quality parameters and performance evaluation criteria for clear sky and under rain conditions.
• Transmission techniques and satellite link design. Design examples for fixed as well as mobile communication systems.
• Multiple access techniques for satellite communication networks (TDMA, FDMA, CDMA). VSAT Networks, topologies and architectures.