Hierarchical Constructive Interference Precoding Design for Downlink Secure Communication Systems

This paper investigates the threat of eavesdroppers in a multi-user multiple-input single-output (MISO) communication system. To counteract eavesdropping and improve communication performance, propose a hierarchical precoding method leveraging the constructive interference (CI) strategy.In view of the constructive interference of the internal constellation point restriction in the constellation diagram, the inner and outer layers are depicted separately, breaking the traditional limitation of the inner constellation points. The hierarchical precoding expression is derived by using the signal superposition and the connection between the symbol scaling and phase rotation measures. The experimental results show that the proposed method can reduce the bit error rate of legitimate users and increase the bit error rate of eavesdroppers, which shows the feasibility and effectiveness.