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, but they also contribute to increase the network power consumption. 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 by adjusting the cell size to the traffic load, hence limiting interference. However, it requires full knowledge of the channel conditions and power allocation strategies of neighboring cells. Its implementation becomes more challenging in broadband heterogeneous networks due to the channel frequency selectivity, the power difference between base station types, and the required network coordination. Therefore, we propose a cell breathing approach for green heterogeneous networks, referred to as path loss-based cell breathing (PL-CB), which uses only path loss information to limit the interference caused to neighboring cells. It achieves a higher energy efficiency and a 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.