How does Timing Advance (TA) works in LTE?
In LTE, when UE wish to establish RRC connection with eNB, it transmits a Random Access Preamble, eNB estimates the transmission timing of the terminal based on this. Now eNB transmits a Random Access Response which consists of timing advance command, based on that UE adjusts the terminal transmit timing.
The timing advance is initiated from E-UTRAN with MAC message that implies and adjustment of the timing advance.
See Timing Advance (TA) in LTE for further details.