Title :
Performance of orthogonal short-time Fourier signaling over doubly dispersive channels
Author :
Liu, Ke ; Kadous, Tamer ; Sayeed, Akbar M.
Author_Institution :
Dept. of Electr. & Comput. Eng., Wisconsin Univ., Madison, WI, USA
Abstract :
Orthogonal short-time Fourier (STF) basis functions are natural for communication over channels that are selective in both time and frequency. However, the STF basis functions in general interfere with each other due to the loss of orthogonality by channel dispersion. It is shown that the channel spread factor, the product of multipath and Doppler spreads, plays a key role in determining system performance. Smaller spread factors result in lower interference. A set of appropriately chosen STF basis functions serve as approximate channel eigenfunctions. A simple and approximately optimal pulse scale adaptation rule is derived to minimize interference by matching pulse properties to channel characteristics. It is also shown that ergodic capacity of doubly dispersive channels deviates from that of flat fading channels as channel spread factor increases. In particular, moments of the eigenvalue distribution of dispersive channels agree with those of flat fading channels up to certain order that is inversely proportional to channel spread factor.
Keywords :
Doppler effect; Fourier transforms; approximation theory; channel capacity; dispersive channels; eigenvalues and eigenfunctions; fading channels; multipath channels; radiofrequency interference; telecommunication signalling; Doppler spreads; STF basis functions; approximate channel eigenfunctions; approximately optimal pulse scale adaptation rule; channel characteristics; channel spread factor; doubly dispersive channels; eigenvalue distribution moments; ergodic capacity; flat fading channels; interference; multipath; orthogonal short-time Fourier basis functions; pulse properties; short-time Fourier signaling; system performance; Dispersion; Drives; Eigenvalues and eigenfunctions; Fading; Frequency; Interference; Prototypes; Scattering; Signal to noise ratio; Statistics;
Conference_Titel :
Information Theory, 2002. Proceedings. 2002 IEEE International Symposium on
Print_ISBN :
0-7803-7501-7
DOI :
10.1109/ISIT.2002.1023629