Identification of SM-OFDM and AL-OFDM Signals Based on Their Second-Order Cyclostationarity

Automatic signal identification (ASI) has important applications to both commercial and military communications, such as software-defined radio, cognitive radio, spectrum surveillance and monitoring, and electronic warfare. While ASI has been intensively studied for single-input single-output systems, only a few investigations have been recently presented for multiple-input multiple-output (MIMO) systems. This paper introduces a novel algorithm for the identification of spatial multiplexing (SM) and Alamouti (AL)-coded orthogonal frequency-division multiplexing (OFDM) signals, which relies on second-order signal cyclostationarity. Analytical expressions for the second-order cyclic statistics of the SM-OFDM and AL-OFDM signals are derived and further exploited for algorithm development. The proposed algorithm provides a good identification performance with low sensitivity to impairments in the received signal, such as phase noise, timing offset, and channel conditions.