Low Complexity Precoder Design for Delay Sensitive Multi-Stream MIMO Systems

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 The transmitter is assumed to have knowledge of outdated channel state information (CSIT) as well as the joint queue state information (QSI) of the L buffers. Using static sorting of the L eigenchannels, we decompose the L-dimensional MDP into L independent 1-dimensional MDP and derived low complexity precoding and power control policies (with linear complexity) to minimize average delays of the L application streams.