On the effectiveness of single and multiple base station sleep modes in cellular networks

We then consider heterogeneous networks in which cells with different coverage areas and different amounts of traffic coexist. In particular, we focus on the common case in which some micro-cells provide additional capacity in a region covered by an umbrella macro-cell, and we prove that the optimal scheduling of micro-cell sleep times is in increasing order of load, from the least loaded to the most loaded. This provides a valuable guideline for the scheduling of sleep modes (i.e., of low-power configurations) in complex heterogeneous networks.