Date Added: Apr 2012
This paper develops the capacity of sampled analog channels under a sub-Nyquist sampling rate constraint. The authors consider a general class of time-preserving sampling methods which includes irregular non-uniform sampling. Their results indicate that the optimal sampling structures extract out a set of frequencies that exhibits the highest SNR among all spectral sets of measure equal to the sampling rate. The sampled capacity can be attained through filter-bank sampling with uniform sampling at each branch with possibly different rates, or through a single branch of modulation and filtering followed by uniform sampling, and the sampled capacity is monotonically non-decreasing with the sampling rate.