An uncertainty relation for WSS processes and its application to WSSUS systems

An uncertainty relation of the same kind as the one by Heisenberg is established between the coherence interval and the spectral spread of zero-mean wide-sense-stationary mean-square-continuous processes whose spectrum has a finite second moment. Pairs of estimates of the coherence bandwidth and of the corresponding delay spread which have been obtained from measurements in an indoor radio environment are confined as stated by this uncertainty relation.