Abstract
With rapid growth of cellular systems, energy consumption has become a critical issue. The existing cellular network planning is performance-oriented, whose objective is to satisfy peak traffic requirements, without too much considerations on energy efficiency. Unfortunately, real-world traffic profiles have indicated that in most time, most of the cells are in low utilization. Switching off certain cells in low traffic period for some time is proved energy-efficient. To switch off cells, remaining operating cells need to extend their coverage by cell zooming to guarantee service. However, such zooming might be insufficient, depending greatly on cell configurations.
In this paper, we consider energy efficiency in cellular network planning. We introduce a new parameter for traffic estimation, which is low traffic time ratio τ . In order to switch off more cells for insufficient cell zooming, two solutions are feasible: to deploy smaller but more cells or to implement coverage extension technologies. We focus on former solution to determine cell configurations and propose an evaluation method to determine whether certain cell deployment is energy-efficient and how much energy it could save, compared with traditional planning. It is shown that when cell zooming ratio is reaching sufficient for certain switching-off scheme, deploying more cells could be more energy-efficient. Also, after exceeding the threshold, the larger the parameter τ is, the more energy-efficient our solution is.
IV. CONCLUSION
We have considered energy saving in cellular network planning stage. An evaluation method is proposed to determine whether or not to adjust deployment obtained from traditional planning in order to switch off more cells, which normally requires remaining active cells to extend their coverage to certain extent. This requirement could be achieved with cell zooming by increasing transmit power. Even if cell zooming is insufficient, it is still possible to deploy smaller but more cells to increase energy efficiency if cell zooming ratio is reaching sufficient and low traffic time ratio is larger than certain threshold.
