LTE-Advanced (4.5G) — Rel-10, Rel-11, Rel-12 (2011-2014)
True 4G meeting IMT-Advanced requirements with Carrier Aggregation up to 100 MHz, Enhanced MIMO 8x8, CoMP, Relay Nodes, and Heterogeneous Networks.
LTE-Advanced is the evolution of LTE that meets IMT-Advanced requirements (true 4G). It was standardized in Rel-10 (2011), Rel-11 (2012), and Rel-12 (2014).
Carrier Aggregation (CA) is the flagship feature, combining up to 5 component carriers for a maximum bandwidth of 100 MHz. CA supports intra-band contiguous, intra-band non-contiguous, and inter-band aggregation.
Enhanced MIMO extended to 8x8 downlink and 4x4 uplink with advanced transmission modes including TM9 and TM10. MU-MIMO allows serving multiple UEs on the same time-frequency resources.
CoMP (Coordinated Multi-Point) coordinates transmission/reception across cells using techniques like Joint Transmission, Dynamic Point Selection, and Coordinated Scheduling/Beamforming.
Rel-12 introduced Dual Connectivity (simultaneous connection to macro and small cells) and Device-to-Device (D2D/ProSe) communication.