Adaptive Index Modulation for Parallel Gaussian Channels With Finite Alphabet Inputs

Abstract

In this paper, we extend the concept of adaptive spatial modulation to the parallel Gaussian channel with finite alphabet input and propose a transmit scheme called adaptive index modulation (AIM). In the proposed scheme, the transmitter adaptively selects the index modulation pattern, consisting of the active channel subset and the associated signal constellations, according to the criterion of maximizing the minimum squared Euclidean distance. To reduce the complexity, first, the number of candidate patterns in the selection procedure is reduced by employing the relation of the normalized signal constellations with different modulation orders. Second, a simple lookup table method is presented. Finally, the performance of the proposed scheme is demonstrated in both the scenarios of multicarrier transmission and multiantenna transmission by computer simulations.