Downlink Transmit Power Calibration for Enterprise Femtocells

Downlink transmit (Tx) power calibration is necessary in femtocell deployments to achieve a good tradeoff between downlink femtocell coverage and interference to other macrocells and femtocells. Developing a practical Tx power calibration scheme that provides excellent performance in different deployment scenarios is challenging. In this paper, we present an enterprise deployment framework that consists of coverage planning and Tx power calibration using technician assistance. The Tx power calibration algorithms presented here use mobile feedback to learn key information such as surrounding RF environment, required coverage range, and interference impact to other cells to adapt to different deployments. Both centralized and distributed Tx power calibration algorithms are evaluated for multi-femto enterprise. It is shown that the distributed algorithm, is simple, efficient and performs very close to the centralized algorithm. Furthermore, over-the-air field tests highlight the practical efficacy of the distributed algorithm in providing excellent femtocell coverage indoors with minimal leakage to outdoors.