A method of managing multiple timing advance (TA) groups, maintaining multiple TA timers, and performing UL synchronization in a multi-carrier wireless system is provided. When a new component carrier (CC) is configured, it is assigned to a TA group having a TA group identifier. The TA groups are managed statically or dynamically. The TA group identifier is used to uniquely identify the TA group in the operations of uplink (UL) timing synchronization. Multiple TA timers are assigned to multiple TA groups. The TA timers may have different values for different TA group. Different embodiments of UL timing adjustments for multiple TA groups are provided.