Modulation Method Based On The Physical Layer Encryption Concealment Algorithm Research

The rapid development of cognitive radio technology has been widely used in the field of communication confrontation and wireless communication reconnaissance, wireless signal’s frequency, bandwidth, modulation mode is very easy to be detected, which caused a great threat to the safety of wireless communication system especially the military wireless communication. The traditional wireless communication security mainly implemented in the link layer, which only protect the date, can not achieve the protection of the air interface and modulation. Therefore, the study of modulation mode’s protection based on encryption in the physical layer has important practical value and theoretical significance. Through the protection of the modulation mode, the attacker unable to determine the modulation mode from the intercepted signal, and thus can not launch targeted attacks to the wireless communication system, which ensure the security of wireless communication.This article studies the modulation mode identification method based on instantaneous parameters, constellation and higher order statistics in the cognitive network, we come to a common basis for these method to achieve the modulation recognition:different modulation has different constellation in the complex plane. Based on this, we design two algorithms to protect the modulation mode in the physical layer. One based on constellation rotation and amplitude regulation, the other based on unitary matrix. Both of them disturb the OFDM constellation and protection of the signal modulation is not detected. Theoretical analysis and simulation results show that the algorithm does not change the perfonnance of the original system; the algorithm not only has good concealment ability, but also can be achieved easily.