Long Term Evolution fundamentally reshaped mobile network design by collapsing the multi-layered 3G hierarchy into a streamlined two-domain architecture. On the radio side sits E-UTRAN, consisting entirely of intelligent base stations called eNodeBs that connect directly to the core. On the network side sits the Evolved Packet Core, where a handful of specialized nodes handle signaling, data routing, and internet connectivity. By eliminating the Radio Network Controller that once sat between base stations and the core, LTE removed a critical bottleneck and reduced user-plane latency to roughly five milliseconds.