  Signal identification represents the task of a receiver to identify the
signal type and its parameters, with applications to both military and
commercial communications. In this paper, we investigate the identification of
spatial multiplexing (SM) and Alamouti (AL) space-time block code (STBC) with
single carrier frequency division multiple access (SC-FDMA) signals, when the
receiver is equipped with a single antenna. We develop a discriminating feature
based on a fourth-order statistic of the received signal, as well as a constant
false alarm rate decision criterion which relies on the statistical properties
of the feature estimate. Furthermore, we present the theoretical performance
analysis of the proposed identification algorithm. The algorithm does not
require channel or noise power estimation, modulation classification, and block
synchronization. Simulation results show the validity of the proposed
algorithm, as well as a very good agreement with the theoretical analysis.
