A Cell Breathing Approach in Green Heterogeneous Networks

Femto base stations constitute a promising solution to cope with the dramatic increase in mobile data traffic. Its widespread deployment in an area already covered by macro base stations requires energy-efficient resource allocation algorithms. Traditionally, full power transmissions are used to satisfy the users' data rate demands, causing interference to neighboring cells. Cell breathing can reduce the total transmit power subject to data rate constraints by adjusting the cell size, and hence limiting interference. However, it requires full knowledge of the channel conditions and power allocation strategies of neighboring cells, which results in delays, complexity, and extra power consumption. Its implementation becomes more challenging in OFDM heterogeneous networks since transmit powers can be allocated independently in each subcarrier and power levels vary greatly between base station types. Therefore, we propose a cell breathing approach for green heterogeneous networks, called path loss-based cell breathing (PL-CB) algorithm, that uses only path loss information to limit the interference caused to neighboring cells. It achieves higher energy efficiency and larger achievable rate region than other state-of-the-art techniques with negligible degradation with respect to the approach with full knowledge of the channel and transmit powers of neighboring cells.