On the capacity of the discrete-time Gaussian channel with delayed feedback

Gives an upper bound on the finite block length capacity of the discrete-time nonstationary Gaussian channel with delayed feedback. With the aid of minimization of a quadratic form, it is proved that the L time-delayed feedback capacity C/sub nFB//sup L/(P) and the nonfeedback capacity C/sub n/(P) satisfy C/sub n/(P)/spl les/C/sub nFB//sup L/(P)/spl les/C/sub n/(P*) where P* is concretely given. The authors give a sufficient condition for C/sub nFB//sup L/(P) to be increased by L time-delayed feedback. Finally the authors also give a necessary and sufficient condition for C/sub nFB//sup 2/(P) of a class of Gaussian channel to be increased by 2 time-delayed feedback.<
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