  This work considers a layered coding approach for efficient transmission of
data over a wireless block fading channel without transmitter channel state
information (CSI), which is connected to a limited capacity reliable link,
known as the bottleneck channel. Two main approaches are considered, the first
is an oblivious approach, where the sampled noisy observations are compressed
and transmitted over the bottleneck channel without having any knowledge of the
original information codebook. The second approach is a non-oblivious
decode-forward (DF) relay where the sampled noisy data is decoded, and whatever
is successfully decoded is reliably transmitted over the bottleneck channel.
The bottleneck channel from relay to destination has a fixed capacity C. We
examine also the case where the channel capacity can dynamically change due to
variable loads on the backhaul link. The broadcast approach is analyzed for
cases that only the relay knows the available capacity for next block, and for
the case that neither source nor relay know the capacity per block, only its
capacity distribution. Fortunately, it is possible to analytically describe in
closed form expressions, the optimal continuous layering power distribution
which maximizes the average achievable rate. Numerical results demonstrate the
achievable broadcasting rates.
