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

Patent metadata

Field	Value
Publication number	US-2024388975-A1
Application number	US-202218696496-A
Country	US
Kind code	A1
Filing date	Sep 29, 2022
Priority date	Sep 29, 2021
Publication date	Nov 21, 2024
Grant date	—

Abstract

The present disclosure relates to a communication system for supporting a high data transfer rate. An embodiment of the present disclosure provides a method, performed by a first gNodeB (gNB)-central unit (CU), of supporting an integrated access and backhaul (IAB) node in performing handover to a second gNB-CU in a wireless communication system. The method includes transmitting 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, transmitting a handover request message including the handover information of the IAB node to the second gNB-CU, receiving context information from the at least one lower node, based on the context information, identifying, 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, supporting intra-CU handover of the lower node identified as the first class, and supporting 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.

First claim

1 . A method, performed by a first gNodeB (gNB)-central unit (CU), of supporting an integrated access and backhaul (IAB) node in performing handover to a second gNB-CU in a wireless communication system, the method comprising:
transmitting 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; transmitting a handover request message comprising the handover information of the IAB node to the second gNB-CU; receiving context information from the at least one lower node; based on the context information, identifying, 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; supporting intra-CU handover of the lower node identified as the first class; and supporting 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.

2 . The method of claim 1 , wherein the context information of the lower node is received as a response to the handover information of the IAB node being transmitted to the lower node, or is received when a channel state of the lower node is changed.

3 . The method of claim 1 , wherein the lower node identified as the second class maintains connection to the IAB node while the IAB node performs inter-CU handover to the second gNB-CU.

4 . The method of claim 1 , further comprising:
setting a timer for the lower node identified as the second class, wherein the lower node identified as the second class maintains connection to the IAB node until the set timer expires.

5 . The method of claim 4 , wherein the handover information comprises information about a handover time of the IAB node, and a start time of the timer is determined based on the handover time.

6 . 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; and 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.

7 . The method of claim 6 , further comprising:
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.

8 . The method of claim 7 , further comprising:
transmitting, via the IAB node, a control signal for intra-CU handover to the lower node identified as the third class.

9 . The method of claim 6 , further comprising:
receiving context information from the at least one lower node connected to the IAB node; identifying, based on the context information, as a third class, a lower node to perform intra-CU handover from among the at least one lower node; and supporting intra-CU handover of the lower node identified as the third class.

10 . 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.

11 . The method of claim 10 , further comprising maintaining connection with the at least one lower node identified as the second class while performing handover from the first gNB-CU to the second gNB-CU.

12 . The method of claim 10 , further comprising:
identifying, from among the at least one lower node identified as the second class, a lower node as a third class, the lower node not having received a control signal for radio resource control (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.

13 . The method of claim 12 , further comprising:
transmitting and receiving control signals for intra-CU handover to and from the lower node identified as the third class.

14 . The method of claim 10 , further comprising:
receiving context information from the at least one lower node identified as the second class; identifying, based on the context information, as a third class, a lower node to perform intra-CU handover from among the at least one lower node identified as the second class; and supporting intra-CU handover of the lower node identified as the third class.

15 . 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.

Assignees

• Samsung Electronics Co Ltd
• Seoul Nat Univ R&Db Foundation

Inventors

• JUNG Byounghoon
• Bahk Saewoong
• Lee Kitaek
• Baek Seungwoo

Classifications

• H04W36/085

  involving beams of access points · CPC title

• H04W36/0058 Primary

  Transmission of hand-off measurement information, e.g. measurement reports · CPC title

• H04W36/08

  Reselecting an access point · CPC title

• H04W76/19 Primary

  Connection re-establishment · CPC title

• H04W84/047

  using dedicated repeater stations · CPC title