Energy efficiency in heterogeneous networks

An attractive approach to meet increasing traffic demands is to densify existing cellular networks with low power nodes. This creates a heterogeneous network. In this paper we analyse the impact of such a densification on the network energy consumption and the possibilities it offers to enhance the network energy efficiency. In a heterogeneous network, the user performance can be significantly improved. This performance increase leads to a shorter transmission time of most data packets, creating longer idle time in the network nodes. In this work, we introduce two node sleep modes operating on a fast and intermediate time scale respectively, in order to exploit short and longer idle periods of the nodes. Our results point out that the total energy consumption of the heterogeneous network featuring the node sleep modes can be maintained at a similar level as the one of the reference network, while the user performance remains superior. At very high traffic load we show that the heterogeneous network can even be more energy-efficient. This means that it is actually possible to increase end-user performance and decrease energy consumption at the same time.