Physical Layer Security of IRS-Assisted Multi-Layer Heterogeneous Networks in Smart Grid

With the deployment of large-scale intelligent terminals in 5G Smart Grid, more communication and computing resources will be sunk to the network edge to meet the ultra-reliable and low-latency requirements of communication networks. However, for the inevitable co-channel interference between adjacent cells, traditional solutions may lead to lower spectrum efficiency or poor signal quality of edge-users. In our work, intelligent reflecting surface (IRS) is used to solve the problem of co-channel interference caused by frequency reuse and improve the transmission capacity of the system. In addition, for the secure transmission issues of massive amount of information in Smart Grid, a low-cost and low-complexity physical layer security transmission scheme is proposed in our work to realize secure transmission. Our work aims at maximizing the system sum-rate by optimizing the transmit beamforming vector at the macro base station (MBS) and multiple micro base stations (mBSs), and the reflection beamforming vector at the IRS with the guarantee of secure communications. Subsequently, the optimization problem is transformed into a convex form, and a non-alternating optimization algorithm based on variable decoupling is designed to obtain high-quality suboptimal solutions. The simulation results show the effectiveness and advantages of the proposed scheme.