Power-Aware Allocation of MBSFN Subframes Using Discontinuous Cell Transmission in LTE Systems

In LTE and its evolutions, energy efficiency is a critical aspect, also in view of the dramatic traffic growth foreseen for the next years. Cell Discontinuous Transmission (DTX) techniques can be important tools to achieve the needed efficiency in the networks, and one possibility is to implement the DTX by switching off the eNB at some subframes (MBSFN subframes) and not in others (where reference signals are also transmitted). Switching schedules in LTE are made for larger periods (e.g., 40/80ms or even more). We present an algorithm that i) estimates how many resources will be needed in a period, and ii) decides how many resource blocks to activate in each subframe so as to maximize the power efficiency. We show that the power saving is significant, close to the theoretical minimum at low loads. This comes with no reduction in cell throughput and without impacting the QoS (a tolerable extra delay is added only at low loads).