Multi-Dimensional Joint Constellation and Precoding Design for MIMO Systems

Abstract

Digital 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 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${M}$ </tex-math></inline-formula> -ary phase-shift keying ( <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${M}$ </tex-math></inline-formula> -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.