Apparatus and method for performing uplink synchronization wireless communication system

A method for a user equipment (UE) performing an uplink synchronization on first and second serving cells in a wireless communication system, comprising:

• by the UE:
• receiving resource control (RRC) configuration for carrier aggregation of the first and second serving cells;
• receiving resource control (RRC) configuration for an extended physical downlink control channel (EPDCCH) for the second serving cell from a base station (BS), wherein the RRC configuration configures the UE with a search space for EPDCCH reception on the second serving cell;
• receiving, in a first subframe containing a first control region and a first data region, an initiation indicator of a first non-contention random access procedure to obtain uplink timing on the first serving cell via the PDCCH in the first control region;
• and
• receiving, in a second subframe containing a second control region and a second data region, an initiation indicator of a second non-contention random access procedure to obtain uplink timing on the second serving cell via only the EPDCCH in the second data region, wherein the UE does not receive the PDCCH in the second control region.

An apparatus comprising:

• one or more processors, configured to cause a user equipment (UE) to:
• receive resource control (RRC) configuration for carrier aggregation of first and second serving cells;
• receive resource control (RRC) configuration for an extended physical downlink control channel (EPDCCH) for the second serving cell from a base station (BS), wherein the RRC configuration configures the UE with a search space for EPDCCH reception on the second serving cell;
• receive, in a first subframe containing a first control region and a first data region, an initiation indicator of a first non-contention random access procedure to obtain uplink timing on the first serving cell via the PDCCH in the first control region;
• and
• receive, in a second subframe containing a second control region and a second data region, an initiation indicator of a second non-contention random access procedure to obtain uplink timing on the second serving cell via only the EPDCCH in the second data region, wherein the UE does not receive the PDCCH in the second control region.