Energy-Efficient Cell-Free Network Assisted by Hybrid RISs

In this letter, we investigate a cell-free network aided by hybrid reconfigurable intelligent surfaces (RISs), which consists of mixture passive and active elements that are capable amplifying reflecting the incident signal. To maximize energy efficiency (EE) system, formulate joint transmit beamforming RIS coefficient optimization problem. deal with fractional objective function, Dinkelbach transform, Lagrangian dual reformulation, quadratic transform utilized, block coordinate descent (BCD) based algorithm proposed to decouple variables. addition, successive convex approximation (SCA) method is applied iteratively tackle non-convexity sub-problems. Simulation results illustrate effectiveness convergence through analyzing EE sum rate performance varying parameter settings. The scheme can achieve 5% 188% gain in compared existing RISs. fast analyzed numerical simulations as well.