A general orthogonal modulation model for software radios

In this letter, a general orthogonal-modulation model to develop new modulations and to identify some widely used modulation schemes is proposed. Based on this general framework, an optimum scheme for non-Gaussian channels under a given set of constraints can be derived. In software radios, the modulation should be changed by tracking this optimum scheme. The proposed model is based on orthonormal vectors, which are obtained by multidimensional rotations. Several widely used modulation schemes are renamed by their consecutive multidimensional rotation angles within the proposed framework. New modulation examples in continuous-wave interference and impulse interference channels are given to illustrate the corresponding local optima.