  Diversity order is an important measure for the performance of communication
systems over MIMO fading channels. In this paper, we prove that in MIMO
multiple access systems (or MIMO point-to-point systems with V-BLAST
transmission), lattice-reduction-aided decoding achieves the maximum receive
diversity (which is equal to the number of receive antennas). Also, we prove
that the naive lattice decoding (which discards the out-of-region decoded
points) achieves the maximum diversity.
