Design of three-dimensional constellations for wireless communication systems

In this paper, a new method of constructing three-dimensional (3-D) signal constellations for digital modulation in wireless communication systems is proposed, which is capable of improving the reliability of transmit signals as compared to conventional two-dimensional (2-D) modulation techniques. More specifically, the proposed method for generating 3-D signal constellations can be translated to an optimization problem of manipulating multiple 2-D signal constellation layers, to which the hexagonal lattice is applied as basic cell. The decoupling of the 3-D space into layered 2-D planes largely eases the design efforts of 3-D constellations. We demonstrate the advantages of the proposed design method through a new 16-ary 3-D signal modulation scheme, which yields a minimum Euclidean distance (MED) larger than that of selected existing schemes under the same power normalisation constraint. Finally, the benefits of the proposed 16-ary 3-D constellation scheme are demonstrated through computer simulations.