Neighbor-dmin precoder for three data-stream MIMO systems

A new precoding strategy, which considers not only the minimum Euclidean distance but also the number of neighbors providing the distance d
_min
, is proposed. Firstly, a new parameterized form of Neighbor-d
_min
precoder is presented, where all angles containing the phase are assumed to be zero to reduce the number of difference vectors providing d
_min
. The optimization problem is, therefore, less complex and the new precoder has less distinct expressions. When a rectangular QAM modulation is used at the transmitter, the general Neighbor-d
_min
precoder for three independent data-streams is proposed. This precoder has only three expressions, which allocate power on one, two, and three virtual subchannels, respectively. Simulation results over Rayleigh fading channels confirm a significant bit-error-rate improvement of the new precoder in comparison with other traditional precoding strategies.