Multi-Dimensional Joint Constellation and Precoding Design for MIMO Systems

Didital modulation and precoding are two key modules for increasing the data rate and reducing the symbol error rate in multiple-input multiple-output (MIMO) systems. Traditionally, these two modules are designed separately, and regular constellations like M-ary phase-shift keying (M-PSK) and quadrature amplitude modulation (QAM) are used for modulation. However, significant gains can be achieved if modulation and precoding are designed jointly for all antennas. Motivated by this, a multi-dimensional joint constellation and precoding design is proposed to optimize the in-phase and quadrature components for all sub-channels of a MIMO channel at once. The objective is to maximize the minimum distance among the symbols. Extensive simulation results indicate that this approach can significantly improve the performance of the state-of-the-art solutions by reducing the symbol error rate and bit error rate.