Handover method in wireless communication system and apparatus therefor

Patent metadata

Field	Value
Publication number	US-11240719-B2
Application number	US-201816765463-A
Country	US
Kind code	B2
Filing date	Nov 16, 2018
Priority date	Nov 19, 2017
Publication date	Feb 1, 2022
Grant date	Feb 1, 2022

Abstract

According to one aspect of the present invention, a method for supporting a user equipment (UE) handover of a target (T)-access and mobility management function (AMF) in a wireless communication system may comprise the steps of: receiving a UE context creation request message from a source (S)-AMF, wherein the UE context creation request message includes packet data unit (PDU) session identifiers (ID) as a handover target and single (S)-network slice selection assistance information (NSSAI) corresponding to each PDU session ID; determining whether the corresponding S-NSSAI is valid in the T-AMF; and sending, to a session management function (SMF), a PDU session update session management (SM) context request message only for a PDU session ID that corresponds to the S-NSSAI determined to be valid according to the determination result, out of the PDU session IDs.

First claim

The invention claimed is:

1. A method for supporting a User Equipment (UE) handover of a Target-Access and Mobility Management Function (T-AMF) in a wireless communication system, the method comprising:
receiving, from a Source-AMF (S-AMF), a create UE context request message, wherein the create UE context request message includes Packet Data Unit (PDU) session Identifiers (IDs) which are related to a target of handover and Single-Network Slice Selection Assistance Information (S-NSSAI) corresponding to each of the PDU session IDs;
determining whether the S-NSSAI corresponding to each of the PDU session IDs is available in the T-AMF;
transmitting a PDU session update Session Management (SM) context request message to a Session Management Function (SMF), only for the PDU session ID corresponding to the S-NSSAI determined to be available in the T-AMF among the PDU session IDs;
receiving a PDU session update SM context response message in response to the PDU session update SM context request message, wherein the PDU session update SM context response message includes a PDU session ID of which handover is accepted by the SMF; and
generating a non-accepted PDU session list including (i) a PDU session ID for which handover is not accepted by the T-AMF and/or the SMF, (ii) and a cause of non-acceptance for the PDU session ID for which handover is not accepted,
wherein the SMF is a network node that determines whether handover for the PDU session ID corresponding to the S-NSSAI determined to be available is accepted,
wherein the cause of non-acceptance of handover includes information representing that the handover is not accepted by the T-AMF because the PDU session is related to an S-NSSAI which is determined to be not available in the T-AMF, and
wherein the non-accepted PDU session list is transmitted to a Source-Radio Access Network (S-RAN).

2. The method of claim 1 , wherein the PDU session non-accepted by the T-AMF is released after receiving a handover notification indicating handover is completed from a Target-Radio Access Network (T-RAN).

3. The method of claim 2 , wherein the release is triggered based on a PDU session release SM context request message including the PDU session non-accepted by the T-AMF being transmitted to the SMF.

4. A Target-Access and Mobility Management Function (T-AMF) for supporting a User Equipment (UE) handover in a wireless communication system, comprising:
a transceiver for transmission and receiving a signal; and
a processor for controlling the transceiver,
wherein the processor is configured to:
receive, from a Source-AMF (S-AMF), a create UE context request message, wherein the create UE context request message includes Packet Data Unit (PDU) session Identifiers (IDs) which are related to a target of handover and Single-Network Slice Selection Assistance Information (S-NSSAI) corresponding to each of the PDU session IDs; and
determine whether the S-NSSAI corresponding to each of the PDU session IDs is available in the T-AMF; and
transmit a PDU session update Session Management (SM) context request message to a Session Management Function (SMF), only for the PDU session ID corresponding to the S-NSSAI determined to be available in the T-AMF among the PDU session IDs;
receive a PDU session update SM context response message in response to the PDU session update SM context request message, wherein the PDU session update SM context response message includes a PDU session ID of which handover is accepted by the SMF, and
generate a non-accepted PDU session list including (i) a PDU session ID for which handover is not accepted by the T-AMF and/or the SMF, (ii) and a cause of non-acceptance for the PDU session ID for which handover is not accepted,
wherein the SMF is a network node that determines whether handover for the PDU session ID corresponding to the S-NSSAI determined to be available is accepted,
wherein the cause of non-acceptance of handover includes information representing that the handover is not accepted by the T-AMF because the PDU session is related to an S-NSSAI which is determined to be not available in the T-AMF, and
wherein the non-accepted PDU session list is transmitted to a Source-Radio Access Network (S-RAN).

Assignees

• Lg Electronics Inc

Inventors

• Park Sangmin
• Kim Taehun
• Youn Myungjune
• Kim Hyunsook
• Ryu Jinsook

Classifications

• H04W36/12 Primary

  Reselecting a serving backbone network switching or routing node · CPC title

• H04W76/34

  Selective release of ongoing connections · CPC title

• H04W76/22

  Manipulation of transport tunnels · CPC title

• H04W36/0033

  with transfer of context information · CPC title

• H04W36/0016

  Hand-off preparation specially adapted for end-to-end data sessions · CPC title