Outage analysis for WCDMA femtocell with uplink attenuation

Femtocells are low-power base stations to extend the cellular network coverage and provide high speed data service for indoor environments. To solve the severe interference problem introduced by unattached co-channel users, the interference mitigation technique, uplink attenuation, can be implemented at femtocell receivers. In this paper, we investigate the close-form outage probability function to quantify the impact of uplink attenuation on femtocell systems. Furthermore, the tradeoff between higher level attenuation resulting in a higher probability to reach the maximum power cap and lower level attenuation with less interference mitigation is demonstrated. Based on this result, we obtain the optimal uplink attenuation factor to minimize the outage probability, which is beneficial to practical system design.