Method and apparatus for performing access initiation and response for cell on unlicensed carrier in wireless communication system

A method for performing, by a user equipment (UE), a random access procedure at a cell on an unlicensed carrier in a wireless communication system, the method comprising:

• receiving an indication, which includes a random access preamble identifier (RAPID) as a dedicated preamble and an index of a second cell, at a first cell from a network;
• transmitting a random access preamble at the first cell to the network;
• and
• receiving a random access response at the second cell from the network,
• wherein a first cell is a first serving cell on a licensed carrier, and
• wherein the second cell is a second serving cell on the unlicensed carrier.

A user equipment (UE) comprising:

• a memory;
• a transceiver;
• and
• a processor, coupled to the memory and the transceiver, that:
• controls the transceiver to receive an indication, which includes a random access preamble identifier (RAPID) as a dedicated preamble and an index of a second cell, at a first cell from a network;
• controls the transceiver to transmit a random access preamble at the first cell to the network;
• and
• controls the transceiver to receive a random access response at the second cell from the network,
• wherein a first cell is a first serving cell on a licensed carrier, and
• wherein the second cell is a second serving cell on the unlicensed carrier.