Abstract
The cyclostationarity feature of modulated signals was widely applied for signal detection and parameter estimation. Previous studies on blind recognition of the modulation type of a received signal are generally performed in a single domain. This paper presents a new recognition approach through establishing a joint delay-cyclic frequency feature decision function, which exploits the different features of the second-order cyclic cumulants for orthogonal frequency division multiplexing (OFDM) signals and single carrier linear digitally modulated (SCLD) signals, in both time delay domain and cyclic frequency domain. We also propose a new statistical test method to classify the two signals under the constraint of possible error recognition, with which an optimal threshold to distinguish OFDM and SCLD signals with the highest accuracy can be theoretically derived. The simulation results are consistent with the performance analysis.
Highlights
Recognition of complex sonar or radar signals has been an important technology for a variety of military and commercial applications
With the new transmission schemes gradually migrating from communication systems into sonar and radar systems, such as single carrier linear digitally modulated (SCLD) and multicarrier modulation in the form of orthogonal frequency division multiplexing (OFDM), the traditional methods employing direction of arrival, carrier frequency, time arrival, pulse amplitude and width cannot meet the requirement of accurate and substantial target recognition
Signal model and second-order cyclostationarity In [11], it proved that the addition of cyclic prefix (CP) to an OFDM symbol provides a useful cyclostationary feature
Summary
Recognition of complex sonar or radar signals has been an important technology for a variety of military and commercial applications. In most cyclostationary-based blind recognition of the modulation methods [6-9], they try to recognize OFDM and SCLD signals only in a single domain. 2. Signal model and second-order cyclostationarity In [11], it proved that the addition of cyclic prefix (CP) to an OFDM symbol provides a useful cyclostationary feature. The analytical closed-form expressions for the secondorder (one-conjugate) CCs and the set of CFs for SCLD signals are given respectively in [7] as follows: crSCLD ðβ; τÞ 1⁄4 J ðτÞρ−1e−j2πβερΛðτÞ þ cωðβ; τÞ ð3Þ κS2;C1LD 1⁄4 fβ∈1⁄2−1=2; 1=2Þjβ 1⁄4 lρ−1; l 1⁄4 1; 2; 3...g; ð4Þ where. Note that the normalized form of CF is used in terms of (4) and (6); the sample quantity is taken as the scale of delay
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