  This paper considers the information bottleneck (IB) problem of a Rayleigh
fading multiple-input multiple-out (MIMO) channel. Due to the bottleneck
constraint, it is impossible for the oblivious relay to inform the destination
node of the perfect channel state information (CSI) in each channel
realization. To evaluate the bottleneck rate, we provide an upper bound by
assuming that the destination node can get the perfect CSI at no cost and two
achievable schemes with simple symbol-by-symbol relay processing and
compression. Numerical results show that the lower bounds obtained by the
proposed achievable schemes can come close to the upper bound on a wide range
of relevant system parameters.
