Energy saving schemes for self-backhauled Small Cells in LTE-Advanced networks

In the present study self-backhauled small cells for LTE-Advanced (a particular kind of small cells with wireless backhauling) are analyzed from the energy efficiency point of view. We perform an assessment of system performances with respect to traditional homogeneous LTE-Advanced networks, not only in terms of capacity and energy consumption, but also showing the potential impacts on the Quality of Service (QoS) of the system. In particular the self-backhauled small cell architecture considered in this paper is based on the type I relay architecture specified in Release 10 of 3GPP. Moreover, a scheduling framework based on MBSFN subframe switching is described and proposed as potential enabler for further energy efficiency enhancements. In addition, a possible Centralized RAN (C-RAN) implementation is described, consisting in a partially centralized algorithm and the application of this mechanism in a centralized processing unit instructing local scheduling entities implemented in the protocol stack of Small Cells. The presence of these schedulers in conjunction with on-board sleep-modes can be a promising tool for maximizing energy efficiency benefits in conditions of low traffic load. System level simulation results showed that these Small Cells in urban and suburban environments can satisfy the need of increasing traffic demand by providing an higher energy efficiency without compromising the QoS and the system capacity.