QoD aware Energy Efficient Active RIS-assisted Multi-User Multi-Stream Precoding by Scalable Complex Iterations

The paper provides the first investigation on energy efficiency (EE) in delivering multi-stream information to multiple multi-antenna users using an active reconfigurable intelligent surface (aRIS)-assisted system. We proposed the joint design of the transmit precoders and of the aRIS's quantized power-amplified reconfigurable elements (APREs) to maximize the ratio of geometric mean (GM) log-det to power consumption. A new computationally efficient alternating descent algorithm based on closed-form expressions is developed. Simulation results are provided to demonstrate that the proposed algorithm can achieve both high EE and minimum log-det rate.