Abstract
Femtocells are expected to remarkably enhance network capacity, indoor coverage and introduce brand-new services. However, in co-channel deployment scenarios, and with the femtocell being applied as a closed subscriber group (CSG) access, femtocells can cause severe interference to the neighbouring cells and derive users to the outage. In this paper a downlink power control scheme without additional signalling exchange is proposed, which adjusts the transmit power subject to user's pathloss measurements. However the minimum level of power transmission is constrained to the acquired target SINR of femtocell user that could be set according to the QoS requirements. The performance is confirmed via system level simulations. The results show that, the proposed scheme reduces the outage probability of the macrocell users, and the spectral efficiency of femtocell users is improved. Furthermore, reducing the transmit power level helps in saving more power towards green femtocell networks.