A Novel Wireless Covert Channel for MIMO System

Wireless covert channel by manipulating the distortions of signal in transmission is an important technique. The covert channels are undetectable by making artificial noise modulated from secret messages distribute as normal channel noise. Although the state-of-the-art work has excellent performance, the undetectability of the schemes for Multiple Input Multiple Output (MIMO) system is weak because the correlation of the raw signals received in all antennas. In this paper, a wireless covert channel for MIMO system is proposed to improve the undetectability. According to the distribution of normal channel noise, the secret messages are modulated into artificial noise in the data transmission of MIMO system. Meanwhile, in the channel state information (CSI) transmission, the CSI parameters are modified to reduce the correlation. Experimental results show that the undetectability of the proposed scheme is better than the existing MIMO schemes with the same reliability and transmission rate.