Optimal base station density for power efficiency in cellular networks

In cellular networks, cell size reduction is an important technique for improving the spectral reuse and achieving higher data rates. In addition, it results in power savings as it leads to a decrease in transmit power. However, it is not clear if the transmit power can be indefinitely decreased with the cell sizes. In this paper, we analyze the impact of transmit power reduction (cell size reduction) on the performance of the network. More precisely, we obtain a lower bound on the transmit power such that a minimum coverage and a minimum data rate can be guaranteed. We then analyze the area power consumption metric, which denotes the total power consumed per unit area. Under the constraints of target coverage and target data rate, the area power consumption is minimized and the optimal base station density is obtained. For a path loss exponent α > 4, we observe the existence of a minimum cell size below which shrinking the cell would result in an overall increase of power. However, for α ≤ 4, there exists no such optimal cell-size, as the area power consumption increases with base station density.