A Novel Spectral Efficient Spatial Modulation Scheme

A novel extension of the traditional generalized spatial modulation (GSM) is proposed to improve the spectral efficiency of GSM. In the traditional GSM scheme, the symbols transmitted by different active antenna elements are the same during each symbol period and the number of states of each antenna element is only two i.e. on and off. The two-state constraint over the antenna in GSM is however found by the authors of this paper to generate constellation points that are nonuniformly spaced in the multi-dimensional signal space, which limits the spectral efficiency and deteriorates the reliability of GSM. In order to combat such limitation, a novel extension of GSM, which is termed as multiple antenna state spatial modulation (MAS-SM), is proposed. In the proposed MAS-SM scheme, the number of states of each antenna element is three i.e. positive on, negative on and off, which allows the positive and negative signs of the symbols transmitted by different active antenna elements to be different from each other. We show that such design makes the distribution of the signal vectors in the signal space to be uniform and thus enhances the spectral efficiency and error performance of the traditional GSM scheme. An analytical derivation of the bit error rate (BER) of a MAS-SM receiver using maximum-likelihood (ML) detection is proposed. Furthermore, Monte-Carlo simulations are performed in this paper to validate the error performance of MAS-SM scheme and the theoretical analysis of BER.