Energy-Efficient Secure Communication for IOS Aided CFMMIMO Network

In this article, we investigate the security energy efficiency (SEE) of intelligent omni-surface (IOS) aided cell-free massive MIMO (CFMMIMO) networks. Firstly, we provide a SEE maximization design for the IOS-assisted CFMMIMO network. To address the formulated non-convex, multivariate problem, in particular, we first decouple the problem into two sub-problems, and design corresponding low-complexity algorithms for each sub-problem, including the joint optimization algorithm of the access point (AP) transmission beamforming and artificial noise covariance matrix based on semi-smooth Newton method (SSNM) as well as the joint optimization algorithm of IOS reflection-transmission phase shift matrix based on Riemannian product manifolds-conjugate gradient method (RPM-CG). The two subproblems are then iterated iteratively using the Block Coordinate Descent (BCD) algorithm to obtain the maximum SEE of the IOS-assisted CFMMIMO network. Simulation results show that the proposed algorithm outperforms the five baseline schemes in terms of SEE.