Method and apparatus for inter-central unit (CU) handover of integrated access and backhaul (IAB) node in wireless communication system

A method, performed by a second gNodeB (gNB)-central unit (CU), of supporting an integrated access and backhaul (IAB) node in performing handover from a first gNB-CU in a wireless communication system, the method comprising:

• receiving, from the first gNB-CU, a handover request message comprising handover information determined based on a measurement report for handover of the IAB node;
• transmitting a handover acceptance message of the IAB node to the first gNB-CU, in response to the handover request message;
• supporting the IAB node in performing inter-CU handover from the first gNB-CU;
• performing a radio resource control (RRC) connection re-establishment procedure on the IAB node, and performing an RRC connection re-establishment procedure on at least one lower node connected to the IAB node;
• identifying, from among the at least one lower node of the IAB node, a lower node as a third class, the lower node not having received control signal for RRC connection re-establishment until expiry of a timer preset for the lower node;
• and
• supporting intra-CU handover of the lower node identified as the third class.

A method of performing, by an integrated access and backhaul (IAB) node, handover from a first gNodeB (gNB)-central unit (CU) to a second gNB-CU in a wireless communication system, the method comprising:

• transmitting a measurement report for handover to the first gNB-CU;
• identifying, as a first class, a lower node to perform intra-CU handover, and identifying, as a second class, at least one lower node to perform inter-CU handover from among at least one connected lower node;
• supporting intra-CU handover of the lower node identified as the first class;
• receiving a handover acceptance message from the second gNB-CU via the first gNB-CU;
• and
• performing, based on the handover acceptance message, handover from the first gNB-CU to the second gNB-CU.

A first gNodeB (gNB)-central unit (CU) to support an integrated access and backhaul (IAB) node in performing handover to a second gNB-CU in a wireless communication system, the first gNB-CU comprising:

• a transceiver;
• and
• at least one processor connected to the transceiver,
• wherein the at least one processor is configured to:
• transmit handover information to at least one lower node connected to the IAB node, the handover information being determined based on a measurement report for handover of the IAB node,
• transmit a handover request message comprising the handover information of the IAB node to the second gNB-CU,
• receive context information from the at least one lower node,
• based on the context information, identify, as a first class, a lower node to perform intra-CU handover, and identifying, as a second class, a lower node to perform inter-CU handover from among the at least one lower node,
• support intra-CU handover of the lower node identified as the first class, and
• support inter-CU handover of the IAB node to the second gNB-CU, based on the handover information of the IAB node and a handover acceptance message of the IAB node which is received from the second gNB-CU.