Precoding of Space-Time Block Codes in Multiuser MIMO Channels with Outdated Channel State Information

Motivated by the fact that combining space-time block codes with channel precoding can make the system robust against channel fading while achieving both coding and diversity gains, we propose a joint set of linear precoder designs for uplink multiuser space-time block coded multiple-input multiple-output systems with multipacket reception by exploiting outdated channel state information. In particular, we formulate the design as an optimization problem of minimizing pairwise error probability subject to transmit power constraint for each user. Due to non-convex nature of the optimization problem, we devise an iterative algorithm to solve for linear precoding structure for general space-time block code. For orthogonal space-time block code, we also propose a simplified distributed algorithm to solve for a closed-form solution. Asymptotic analysis of the effect of channel quality on the precoder structure is also presented. Simulation results are provided to demonstrate the effectiveness of the proposed designs for orthogonal and quasi-orthogonal space-time block codes over the conventional beamforming system.