LTE UE Operations Procedures and Anatomy

Once the user equipment (UE) is powered ON, it triggers the CPU reset and initially it performs the booting and system initialization related tasks including device self‐test. In the modem unit, once the system initialization is over and operating system (OS) is loaded into the memory, then OS takes the control and starts executing different tasks, where different modem sublayers and procedures are running as OS threads. In order to synchronize time and frequency with a UE cell the eNB broadcasts two types of downlink physical signals: a primary synchronization signal (PSS); a secondary synchronization signal (SSS). These two signals were especially designed to enable time and frequency synchronization. They also indicate physical layer cell identity, cyclic prefix length, and frequency division duplex (FDD), or time division duplex (TDD) mode used in the cell.