Femtocells in centralized systems: green operation and radio resource management techniques

In this paper, a system of femtocells controlled by a single controller is investigated. In such a scenario, femtocell access points (FAPs) are assumed connected via wired links to a central controller within a certain vicinity (e.g., building, compound, hotel, and campus.). Thus, radio resource management (RRM) and green network operation of LTE femtocell networks are investigated in an integrated wired/wireless system. Consequently, it becomes possible to perform RRM in a centralized and controlled way in order to enhance the quality of service (QoS) performance for the users in the network. Furthermore, energy-efficient operation consisting of switching off redundant FAPs can be implemented. A utility maximization framework is presented, and an RRM algorithm that can be used to maximize various utility functions is proposed. Another algorithm is presented for the scenario of FAP on/off switching to achieve green operation. It consists of selecting the best FAP to switch off, then moving the femto user equipments (FUEs) to other active FAPs without compromising their quality of service (QoS). Simulation results show that the proposed algorithms lead to significant performance gains.