Abstract
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.