Data Power Optimization Algorithm for Downlink Multi-ARS Small Cell Communication Systems.
In this paper, we investigate a novel downlink small cell (SC) system based on the Cell-Free (CF) model, with the deployment of unmanned aerial vehicles (UAVs) as aerial relay stations (ARSs) simultaneously serving users in a specific area. The new SC model concept is expressed in the user-centric idea that the user will choose only one ARS with the best conditions for communication, and the concept of ``cell" or ``cell boundary" will no longer exist. The time division duplex (TDD) mechanism is used for system-wide communication protocol, and the minimum mean squared error (MMSE) technique is applied for downlink channel estimation. We establish the downlink user throughput expression and then propose a Bisection optimization algorithm to control power for downlink data transmission to improve system quality and save energy. We evaluate the downlink multi-ARS SC communication system with and without power optimization in different aspects, such as altering the number of users, the number of ARSs, the number of antennas, and the transmission channel estimation interval. The results also reveal that the system quality is significantly improved when applying the downlink power factor optimization problem.