Further Complexity Reduction Using Rotational Symmetry for EDAS in Spatial Modulation

Euclidean distance antenna selection (EDAS) is an effective transmit antenna selection technique for spatial modulation (SM). However, since an exhaustive search over both the antenna set and the set of conventional constellation points is executed, the computational complexity required to find the optimal solution of EDAS is too high for practical applications. In general, digital modulation constellations have rotational symmetry. In this letter, it is shown that the symmetric constellation points have the same value as EDAS. Hence, only one search is enough for the symmetrical constellation set. Using this proposition, we propose a fast algorithm to find the optimal EDAS solution, which exhibits lower computational complexity than the conventional EDAS solution.