A system and methods for performing phased reconfiguration in a wireless communications system are disclosed. A wireless transmit/receive unit (WTRU) may perform a phased reconfiguration from a source cell to a target cell. The WTRU may be connected to the source cell and may execute a first set of functions towards the source cell. The WTRU may monitor for a first set of preconfigured trigger conditions and a second set of preconfigured trigger conditions. The WTRU may commence a second set of functions towards the target cell based on detection of at least one of the first set of preconfigured trigger conditions while continuing to execute the first set of functions towards the source cell. The WTRU may cease to perform at least a subset of the first set of functions towards the source cell based on detection of at least one of the second set of preconfigured trigger conditions.