Energy Saving and Capacity Gain of Micro Sites in Regular LTE Networks: Downlink Traffic Layer Analysis

We study the effect of deployment of low cost, low power micro base stations along with macro base stations on energy consumption and capacity of downlink LTE. [1] studied this problem, using spectral area efficiency as the performance metric. We show that the analysis proposed in [1] is inaccurate as the traffic layer specifications of LTE networks is not included in the analysis. We also investigate the effect of user association and frequency band allocation schemes on energy consumption and capacity of LTE networks. Specifically, we add the following three important elements to the analysis proposed in [1]: a traffic layer analysis that take both the physical and traffic layer specifications of LTE downlink into account; a threshold-based policy to optimally associate users to base stations; and an allocation scheme to better allocate the frequency band to macro and micro base stations. We investigate all combinations of these elements through numerical evaluation and observe that 1. there are important differences between traffic layer and physical layer analysis, 2. threshold-based user association policy improve the traffic capacity of the network by up to 33% without affecting the energy profile of the network, and 3. considerable energy saving and capacity gain can be achieved thought a careful allocation of the frequency band to macro and micro base stations. Finally, we determine the optimal network configuration and show that up to 46% saving in energy can be achieved compared to the case that no micro base stations are deployed in the network.