  In this paper, we perform a survey on new Third Generation Partnership
Project (3GPP) Long Term Evolution-Advanced (LTE-Advanced)
enhancements,covering the technologies recently adopted by the 3GPP in LTE
Release 11 and those being discussed in LTE Release 12. In more details, we
introduce the latest enhancements on carrier aggregation (CA), multiple-input
multiple-output (MIMO) and coordinated multi-point (CoMP) as well as
three-dimensional (3D) MIMO. Moreover, considering that network nodes will
become very diverse in the future, and thus with heterogeneous network (HetNet)
being a key feature of LTE-Advanced networks, we also discuss technologies of
interest in HetNet scenarios, e.g., enhanced physical data control channel
(ePDCCH), further enhanced inter-cell interference coordination (FeICIC) and
small cells, together with energy efficiency concerns. In particular, we pay
special attention to one of the most important enhancements in LTE Release 12,
i.e., dynamic time division duplex (TDD) transmissions, and present performance
results that shed new light on this topic.
