Broad-band fading channels: signal burstiness and capacity

Author

Subramanian, Vijay G. ; Hajek, Bruce

Author_Institution

Illinois Univ., Urbana, IL, USA

Volume

48

Issue

4

fYear

2002

fDate

4/1/2002 12:00:00 AM

Firstpage

809

Lastpage

827

Abstract

Medard and Gallager (2002) showed that very large bandwidths on certain fading channels cannot be effectively used by direct sequence or related spread-spectrum systems. This paper complements the work of Medard and Gallager. First, it is shown that a key information-theoretic inequality of Medard and Gallager can be directly derived using the theory of capacity per unit cost, for a certain fourth-order cost function, called fourthegy. This provides insight into the tightness of the bound. Secondly, the bound is explored for a wide-sense-stationary uncorrelated scattering (WSSUS) fading channel, which entails mathematically defining such a channel. In this context, the fourthegy can be expressed using the ambiguity function of the input signal. Finally, numerical data and conclusions are presented for direct-sequence type input signals

Keywords

Rayleigh channels; broadband networks; channel capacity; code division multiple access; spread spectrum communication; time-varying channels; DS-CDMA; WSSUS fading channel; ambiguity function; broad-band fading channels; capacity; direct sequence systems; direct-sequence type input signals; fourth-order cost function; fourthegy; information-theoretic inequality; input signal; signal burstiness; spread-spectrum systems; wide-sense-stationary uncorrelated scattering fading channel; Additive noise; Bandwidth; Channel capacity; Cost function; Fading; Gaussian noise; Higher order statistics; Rayleigh scattering; Spread spectrum communication; Transmitters;

fLanguage

English

Journal_Title

Information Theory, IEEE Transactions on

Publisher

ieee

ISSN

0018-9448

Type

jour

DOI

10.1109/18.992762

Filename

992762