Cognitive Optimization Scheme of Coverage for Femtocell Using Multi-Element Antenna

Recently, femtocell has been proposed as a good solution to increase the coverage area and capacity of the wireless communication system as well as meet the increasing demand for high data rate. The femtocell is low-cost, low-power and can be realized by deploying a femto-base-station connected to the core network via a wired-backhaul. Since the femtocell reuses the macrocell spectrum, co-channel interference between femtocell and macrocell should be taken into consideration first of all. The leakage of femtocell´s pilot power to the outside of a residence would cause passing users´ handover events and result in increasing load to the network. In this paper, firstly we put forward a simple method for the femtocell to gain recognition of the residence and network environment, and then according to the obtained knowledge the femtocell carries out self-cofiguration and self-optimization for the purpose of achieving an optimized coverage to improve the in door Quality of Service (QoS) and minimum the interference in the existing network. To implement that we bring up a low-cost multi-element antenna solution and a series of corresponding algorithms, which is mainly based on low-complexity shaped beam forming and power adjusting. The simulation results show that the approaches proposed in the paper greatly reduce the femtocell´s interference to the macrocell and optimize indoor coverage at the same time. These results can provide guidelines for the deployment of femtocell.