Phased-Array Transmission for Secure Multiuser mmWave Communication via Kronecker Decomposition

This paper proposes a multiuser physical layer secure transmission scheme for millimeter-wave communication. We use Kronecker decomposition to design the common transmit vector to synthesize the desired symbols for multiple legitimate receivers in the proposed scheme. Specifically, the algorithm converts the design of common transmit weight for multiuser into the design of sub-weight vectors having the Vandermonde structure. By using Kronecker decomposition, the sub-weight vectors are decomposed into Kronecker factors and designed. To eliminate the message sending towards the undesired directions while guaranteeing the quality of transmission in the target directions, we separate the Kronecker factors into two parts by using the property of the Kronecker product. The first part (the interference cancellation factor) cancels the interference between legitimate users; the second part (the signal enhancement factor) achieves signal enhancement. For a given information symbol, multiple solutions of transmit weight are obtained. By utilizing this time-varying transmit weight, we realize the secure transmission for multiuser. In addition, the proposed algorithm has no restrictions on modulation, and it also has analytical solutions with low computational complexities. Simulations are presented to verify the effectiveness of the algorithm under various situations.