Research On Performance Of Low-probability-of-detection Signal Based On Frctional Fourier Domain

With the rapid development of communication technology and signal processing methods, various efficient signal detection and identification methods appear in the non-cooperative communication, the requirements of communication system are no longer limited to effectiveness and reliability, security also appears increasingly important. In order to prevent non-partner to intercept and detect the target signal, LPI and LPD signal has been proposed, and its application in non-cooperative communication becomes more and more prevalent. Currently, the most common LPI/LPD signals are spread spectrum signals and frequency-hopping signals. However, too much research has been done on spread spectrum and frequency-hopping technology, which results in many effective detection methods being proposed for SS signals and FH signals. Under this background, this paper proposes a new LPD signal in the fractional-Fourier domain. And its anti-detection and anti-identification performances are discussed in detail.Firstly, the basic theory of WFRFT which is a new signal processing method in fractional-Fourier domain has been summarized in this paper. Then, we proposed a digital communication system in fractional-Fourier domain based on WFRFT and its corresponding signal. And then we introduced the basic features of the fractional-Fourier domain signal. Especially, we studied the parameter anti-detection performance of the fractional-Fourier-domain signal produced by SP-4-WFRFT and MP-4-WFRFT in detail. Depending on the simulation results, MP-4-WFRFT can improve the workload of non-cooperative receiver in effect.Secondly, a new signal detection method has been introduced by combining energy-detection and correlation-detection based on the amplitude spectrum. Then,we analyzed the LPD characteristic of SP-4-WFRFT signal and MP-4-WFRFT signal by using this signal detection method. The simulation results showed that the detection probability of fractional-Fourier domain signal can be reduced obviously when the non-partner can not get the accurate transformation parameters. By this analysis, we can further verify its LPD characteristic.Finally, the basic concept of modulation recognition has been introduced. Then we studied the modulation recognition performance of SP-4-WFRFT signal and MP-4-WFRFT signal respectively based on the higher-order cumulant. The simulation results showed that the recognition probability of fractional-Fourier domain signal by using the higher-order cumulant method can be reduced significantly when the non-partner can not get the transformation parameters accurately. By comparing with the recognition probability of normal modulatedsignal, we can verify the anti-detection capacity of fractional-Fourier-domain signal once again.