A Blind Modulation Recognition Algorithm Suitable for MIMO-STBC Systems

Blind modulation recognition is a challenging problem in Multiple Input Multiple Output (MIMO) systems in association with Space-Time Block Code (STBC). To our knowledge, there is no method reported in literature to deal with this problem. In this paper, a modulation classifier is presented based on Maximum Likelihood (ML) without utilizing the Channel State Information (CSI) and coding matrix. The modulations are classified into two categories according to the independence of the source signals: independent and non-independent constellations. The modulation recognition based on the ML classifier is discussed for independent (resp. non-independent) constellations by using Independent (resp. Multi-dimensional Independent) Component Analysis. Simulations show that our algorithm can work with high recognition probabilities in MIMO-STBC communication systems when CSI and coding matrix are unavailable.