Indoor use of mobile phones is growing. Signal penetration into buildings induces severe attenuation which leads to poor indoor mobile coverage. Thus achieving adequate indoor signal to noise and interference ratio is challenging. If operators want to stimulate 3G usage as an alternative to the competitive WIFI solution, they will have to offer better data rates when users are at home or at work. The emerging femtocell solution may be the last step toward broadband mobile internet. Radio planning is not obvious for a plug-and-play femtocell device, which will inherently have an unpredictable deployment. In this paper we evaluate the performance that a femtocell system can achieve when coexisting with an overlaying macrocell system. We propose a double reuse frequency scheme for the assessment of the SINR at the femtocell level. We show that femtocells can definitely provide a meaningful improvement in the data rates experienced by the femtocell user equipment.