Secure transmission in wireless ad-hoc networks without CSI at the destination

Due to the openness of wireless communication, the transmission in ad hoc networks is vulnerable to eavesdropping by illegitimate users. The traditional work generally assumes that both the transmitter and the receiver know the channel state information (CSI) of the legitimate channel, but less consideration is given to the scenario where the receiver does not know the CSI. In order to improve the security performance in this scenario, we propose novel transmission schemes by introducing artificial noise or self-interference across time. The artificial noise scheme can improve security significantly but consumes remarkable power, so we instead fuse multiple signals through a Hadamard matrix to actively introduce self-interference. It turns out that the latter scheme has obvious advantages since it improves security and saves power simultaneously. We analyze the achievable secrecy rate of the proposed scheme, and exhibit simulation results to verify the theoretical analysis.