Abstract: An algorithm is proposed based on fourth-order cyclostationarity to classify Spatial Multiplexing (SM) and Alamouti space-time block code (STBC) with transmission impairments when a single antenna is employed at the receiver. Firstly, we prove the feature that Alamouti STBC signals hare cyclic frequency. Secondly, the fourth-order cyclic cumulants of the received samples are calculated to observe the cyclic frequency. Thirdly, we exploit the discriminating features provided by cyclic frequency of different STBCs, and construct cyclostationarity test to detect the cyclic frequency to achieve the classification. The algorithm can work in single received antenna scenarios. Monte Carlo simulation shows that the algorithm does not require the channel state information, modulation of the transmitted signal, carrier phase and time offset. It does not need to accurately know the carrier frequency offset and performs well.

Key words: space-time block code (STBC), cyclostationarity test, signal classification, transmission impairments, single receive antenna