  In this paper, we consider delay-optimal MIMO precoder and power allocation
design for a MIMO Link in wireless fading channels. There are $L$ data streams
spatially multiplexed onto the MIMO link with heterogeneous packet arrivals and
delay requirements. The transmitter is assumed to have knowledge of the channel
state information (CSI) as well as the joint queue state information (QSI) of
the $L$ buffers. Using $L$-dimensional Markov Decision Process (MDP), we obtain
optimal precoding and power allocation policies for general delay regime, which
consists of an online solution and an offline solution. The online solution has
negligible complexity but the offline solution has worst case complexity ${\cal
O}((N+1)^L)$ where $N$ is the buffer size. Using {\em static sorting} of the
$L$ eigenchannels, we decompose the MDP into $L$ independent 1-dimensional
subproblems and obtained low complexity offline solution with linear complexity
order ${\cal O}(NL)$ and close-to-optimal performance.
