  This paper investigates delay-distortion-power trade offs in transmission of
quasi-stationary sources over block fading channels by studying encoder and
decoder buffering techniques to smooth out the source and channel variations.
Four source and channel coding schemes that consider buffer and power
constraints are presented to minimize the reconstructed source distortion. The
first one is a high performance scheme, which benefits from optimized source
and channel rate adaptation. In the second scheme, the channel coding rate is
fixed and optimized along with transmission power with respect to channel and
source variations; hence this scheme enjoys simplicity of implementation. The
two last schemes have fixed transmission power with optimized adaptive or fixed
channel coding rate. For all the proposed schemes, closed form solutions for
mean distortion, optimized rate and power are provided and in the high SNR
regime, the mean distortion exponent and the asymptotic mean power gains are
derived. The proposed schemes with buffering exploit the diversity due to
source and channel variations. Specifically, when the buffer size is limited,
fixed channel rate adaptive power scheme outperforms an adaptive rate fixed
power scheme. Furthermore, analytical and numerical results demonstrate that
with limited buffer size, the system performance in terms of reconstructed
signal SNR saturates as transmission power is increased, suggesting that
appropriate buffer size selection is important to achieve a desired
reconstruction quality.
