Robust power control for femtocell networks under outage-based QoS constraints

This paper studies a robust uplink power control scheme with imperfect channel state information (CSI) in two-tier femtocell network systems. Aiming at enhancing the system’s robustness, we formulate an outage-based robust optimization problem. Specifically, we focus on two scenarios including partial CSI feedback and no CSI feedback. In the former scenario, channel gain error vectors obey multivariate Gaussian distributions. We propose a novel transformation method, which is based on Q-radial distribution, to obtain the closed-form expressions. In the latter scenario, channel gain includes path loss attenuation and Rayleigh fading. For the complex channel models, a novel method is given to extract closed-form approximations. Then, two iterative algorithms are provided. Also, admission control algorithm is applied. Finally, simulation results are given to show the validity of our proposed algorithms.