4G

4G (fourth-generation cellular network technology) is the predecessor to 5G and the first generation to treat the mobile network as an all-IP packet-switched infrastructure rather than a circuit-switched voice system. Standardized by 3GPP Releases 8 through 14, it introduced LTE (Long Term Evolution) as its air interface, achieving peak download rates of 100 Mbps to 1 Gbps depending on channel configuration. Where 3G was a network for mobile phones, 4G was a network for mobile computing — and that shift in design target changed the architecture more than the bitrate.

The architectural legacy of 4G is the flat IP core: voice became just another application (VoLTE), and the network's purpose was generalized from connectivity to service delivery. This generalization created the preconditions for network function virtualization, which 5G would later exploit. But 4G also entrenched a centralized architecture — the mobile core as a single point of control — that 5G's edge computing model would eventually challenge. The history of cellular evolution is not a smooth gradient; it is a series of punctuated equilibria where each generation solves the previous generation's bottleneck while creating the next.