Optimization of Non-Uniform Constellations with Reduced Degrees of Freedom

In this paper, multiple algorithms to design non-uniform constellations (NUCs) are reviewed, it is found that the degrees of freedom (DOF) is still large when designing 2-dimensional NUC (2D-NUC). To this end, we propose a two-step algorithm to design 2D-NUC, which consists of initial constellations design and a subsequent iterative optimization. By imposing more limitations on the initial constellations, the number of parameters to be optimized is reduced. Based on that, a set of 2D-NUC which outperforms that adopted by ATSC 3.0 is finally presented by applying the proposed iterative optimization algorithm.