Optimizing the performance of D-BLAST lattice codes for MIMO fading channels

We focus on the space-time block codes proposed by Prasad and Varanasi (see Proc. Allerton Conf. on Comm., Control, and Comput., Monticello, IL, Oct. 2002) for the quasi-static multi-input multi-output (MIMO) Rayleigh fading channel, referred to as the D-BLAST lattice codes. We propose a soft decision feedback decoder based on the list implementation of the sphere decoder to mitigate error propagation and demonstrate the performance improvements accrued by this decoder through simulation results. A power optimization result is established which can be employed on any full modulation diversity lattice to obtain further performance gains. We examine the coding gain achieved by the lattice codes and show that in general, constructing a full modulation diversity lattice which also optimizes the coding gain is a challenging problem.