  In this paper, we consider dynamic precoder/decorrelator optimization for
multimedia streaming in MIMO interference networks. We propose a truly
cross-layer framework in the sense that the optimization objective is the
application level performance metrics for multimedia streaming, namely the
playback interruption and buffer overflow probabilities. The optimization
variables are the MIMO precoders/decorrelators at the transmitters and the
receivers, which are adaptive to both the instantaneous channel condition and
the playback queue length. The problem is a challenging multi-dimensional
stochastic optimization problem and brute-force solution has exponential
complexity. By exploiting the underlying timescale separation and special
structure in the problem, we derive a closed-form approximation of the value
function based on continuous time perturbation. Using this approximation, we
propose a low complexity dynamic MIMO precoder/decorrelator control algorithm
by solving an equivalent weighted MMSE problem. We also establish the technical
conditions for asymptotic optimality of the low complexity control algorithm.
Finally, the proposed scheme is compared with various baselines through
simulations and it is shown that significant performance gain can be achieved.
