Secure communication system based on alterable-parameter 4-weighted fractional fourier transform

By discussing the development of 4-WFRFT, a discrete sequence algorithm for 4-WFRFT based on DFT is introduced and this makes it possible to use 4-WFRFT in a discrete time system. On the basis of analyzing the rotating, squeezing effect to the digital signal constellation by 4-WFRFT process also the similarity of 4-WFRFT signal to Gaussian distribution and the anti-scanning competence of 4-WFRFT signal, an alterable-parameter secure communication system is introduced based on 4-WFRFT secure communication system. Moreover, in the light of frequency-hopping patterns, a dynamic alterable-parameter strategy for single parameter 4-WFRFT and three strategies for multi-parameters 4-WFRFT are designed to avoid a non-receiver's intercepting and decoding. "Tracking coefficient" is defined to judge the anti-scanning capacity. The results of simulation show that the alterable-parameter 4-WFRFT secure communication system has strong practical significance.