  This paper proposes an efficient identification algorithm for spatial
multiplexing (SM) and Alamouti (AL) coded orthogonal frequency division
multiplexing (OFDM) signals. The cross-correlation between the received signals
from different antennas is exploited to provide a discriminating feature to
identify SM-OFDM and AL-OFDM signals. The proposed algorithm requires neither
estimation of the channel coefficients and noise power, nor the modulation of
the transmitted signal. Moreover, it does not need space-time block code (STBC)
or OFDM block synchronization. The effectiveness of the proposed algorithm is
demonstrated through extensive simulation experiments in the presence of
diverse transmission impairments, such as time and frequency offsets, Doppler
frequency, and spatially correlated fading.
