Spectral efficiency of peak power limited rician block-fading channels

In this paper, the capacity and spectral efficiency of peak power limited Rician block-fading channels when neither the receiver nor the transmitter knows the fading coefficients is studied. The capacity-achieving input amplitude distribution of the average power limited memoryless unknown Rayleigh fading channel is discrete with a finite number of mass points is proved. The spectral-efficiency and the bit energy tradeoff in the low power regime is studied.