Title :
On the information content of scattered waves
Author :
Franceschetti, Massimo
Author_Institution :
Dept. of Electr. & Comput. Eng., UC San Diego, La Jolla, CA, USA
Abstract :
A basic trade-off between spatial and frequency diversities available for communication with multiple scattered waves is presented. A rigorous notion of the total number of space-frequency degrees of freedom of the field is introduced based on Slepian´s theory of spectral concentration of L2 functions. This definition agrees with the “rule of thumb” of multiplying the degrees of freedom available in space and frequency. However, while the mathematical definition requires both frequency and spatial bandwidths to scale simultaneously, a physical argument precludes such a scaling to occur in practice. Hence, since the nature of wireless communication prevents unbounded and simultaneous spatial and frequency diversity gains, rule of thumb definitions of degrees of freedom should be taken with care as they are inherently imprecise.
Keywords :
diversity reception; electromagnetic wave scattering; L2 functions; Slepian´s theory; frequency bandwidths; frequency diversities; information content; mathematical definition; multiple scattered waves; space-frequency degrees of freedom; spatial bandwidths; spatial diversities; wireless communication; Antennas; Bandwidth; Eigenvalues and eigenfunctions; Frequency diversity; Information theory; Scattering; Wireless communication;
Conference_Titel :
Information Theory Proceedings (ISIT), 2012 IEEE International Symposium on
Conference_Location :
Cambridge, MA
Print_ISBN :
978-1-4673-2580-6
Electronic_ISBN :
2157-8095
DOI :
10.1109/ISIT.2012.6283519