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.