4G LTE

LTE fundamentals

LTE is the foundation of modern packet-based mobile networks and an important bridge for understanding 5G architecture.

Architecture

LTE combines the E-UTRAN radio access network with the EPC core. The eNodeB handles radio access while the EPC provides mobility, session and packet-data functions.

EPC basics

The EPC includes key functions such as the MME, Serving Gateway and PDN Gateway. Understanding their roles makes LTE signalling and bearer troubleshooting much easier.

Mobility

LTE mobility includes measurement, handover preparation and execution between cells. Log analysis often requires following the sequence across RRC and core signalling.

RRC

RRC controls radio connection state and configuration. Connection setup, reconfiguration, measurements and release are common areas to inspect during device testing.

VoLTE

VoLTE uses IMS to provide voice as a packet service. SIP signalling, dedicated QoS and LTE bearer behaviour all need to work together for a successful call.