Fourth-order moment-based identification of SM and Alamouti STBC for cognitive radio

Cognitive radio (CR) systems require knowledge of the signal environment if they are to coexist with the primary (incumbent) users of the radio spectrum. Consequently, signal identification is a major task of a CR. This paper proposes a novel identification algorithm for spatial multiplexing (SM) and Alamouti space-time block code (AL STBC) transmissions, when the CR employs a single receive antenna. This algorithm relies on the fourth-order moment as a discriminating signal feature and uses a maximum likelihood (ML) criterion for decision making. Its performance is investigated through theoretical analysis and simulation experiments.