# US 11,452,163 B2 · Method for interaction between layers in wireless communication system and apparatus therefor > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 11,452,163 B2 - Document ID: US11452163B2 - Status: Granted - Kind: B2 - Application number: 16/818,331 - Filed: 2020-03-13 - Published: 2020-07-09 - Granted: 2022-09-20 - Earliest claimed: 2017-03-20 - Assignees: LG Electronics Inc. - Applicants: LG Electronics Inc. - Inventors: Sangmin Park; Hyunsook Kim; Jinsook Ryu; Dongsoo Kim; Myungjune Youn - Web page: https://patentgrep.com/patent/US11452163B2 ## CPC - H04W 76/25: Maintenance of established connections - H04W 80/02: Data link layer protocols - H04W 8/08: Mobility data transfer - H04W 48/17: {Selecting a data network PoA [Point of Attachment]} - H04W 76/18: Management of setup rejection or failure - H04W 76/30: Connection release - H04W 80/10: adapted for {application} session management, e.g. SIP [Session Initiation Protocol] {(connection management H04W76/00; arrangements for session management H04L67/14)} - Y02D 30/70: in wireless communication networks - H04W: WIRELESS COMMUNICATION NETWORKS (broadcast communication H04H; communication systems using wireless links for non-selective communication, e.g. wireless extensions H04M1/72) - Y02D: CLIMATE CHANGE MITIGATION TECHNOLOGIES IN INFORMATION AND COMMUNICATION TECHNOLOGIES [ICT], I.E. INFORMATION AND COMMUNICATION TECHNOLOGIES AIMING AT THE REDUCTION OF THEIR OWN ENERGY USE ## Abstract A method for forwarding a non-access stratum (NAS) message of a user equipment (UE) in a wireless communication system is disclosed. The method includes sending an uplink (UL) NAS message including a session management (SM) message to an access and mobility management function (AMF), and receiving, from the AMF, an indication message indicating that the SM message is unroutable, wherein indication information indicating that the SM message is unroutable is delivered to a SM sublayer of the UE. ## Claims ### Claim 1 A method performed by an access and mobility function (AMF) operating in a wireless communication system, the method comprising: receiving, from a user equipment (UE), an uplink (UL) non-access stratum (NAS) message that comprises a session management (SM) message; and transmitting, to the UE, a downlink (DL) NAS message that comprises a cause value indicating that the SM message was not forwarded due to routing failure, wherein an indication that the SM message was not forwarded due to routing failure is transferred, from a lower sublayer of the UE to an upper sublayer of the UE, based on the cause value, wherein the SM message is generated in the upper sublayer of the UE and is provided to the lower sublayer of the UE, and wherein the UL NAS message comprising the SM message is sent to the AMF by the lower sublayer of the UE. ### Claim 2 (depends on 1) The method of claim 1, wherein the upper sublayer of the UE is a Session Management (SM) sublayer that performs protocol data unit (PDU) session control, and wherein the lower sublayer of the UE is a Mobility Management (MM) sublayer that performs mobility control of the UE. ### Claim 3 (depends on 1) The method of claim 1, wherein a pre-configured timer is started by the UE, based on the upper sublayer of the UE providing the SM message to the lower sublayer of the UE; and wherein the pre-configured timer is stopped by the UE, and a procedure related to the SM message is stopped, based on the upper sublayer receiving, from the lower sublayer, the indication that the SM message was not forwarded due to routing failure. ### Claim 4 (depends on 3) The method of claim 3, wherein at least one re-transmission of the SM message is performed by the UE, based on the pre-configured timer expiring, and a procedure related to the SM message is stopped by the UE, based on failure of the at least one re-transmission of the SM message. ### Claim 5 (depends on 1) The method of claim 1, wherein the UL NAS message further comprises a data network name (DNN) or single network slice selection assistance information (S-NSSAI) for the selection of a session management function (SMF) to forward the SM message. ### Claim 6 (depends on 2) The method of claim 2, wherein based on the SM message being a message requesting an establishment of a PDU session, the UL NAS message further comprises a PDU session identifier (ID) for the PDU session to which the establishment is requested. ### Claim 7 (depends on 1) The method of claim 1, wherein the lower sublayer forwards, to the upper sublayer, information about whether the SM message not being forwarded due to routing failure is permanent or temporary, together with the indication. ### Claim 8 (depends on 7) The method of claim 7, wherein based on the SM message not being forwarded due to routing failure being permanent, the upper sublayer performs a release procedure for a PDU session or a data network (DN) related to the SM message. ### Claim 9 (depends on 8) The method of claim 8, wherein the upper sublayer includes the PDU session or the DN in a procedure forbidden list and manages the PDU session or the DN. ### Claim 10 (depends on 8) The method of claim 8, wherein based on services related to the PDU session or the DN being required, the upper sublayer requests a deregistration to the lower sublayer. ### Claim 11 An access and mobility function (AMF) configured to operate in a wireless communication system, the AMF comprising: a transceiver; at least one processor; and at least one computer memory operably connectable to the at least one processor and storing instructions that, when executed by the at least one processor, perform operations comprising: receiving, via the transceiver from a user equipment (UE), an uplink (UL) non-access stratum (NAS) message that comprises a session management (SM) message; and transmitting, via the transceiver to the UE, a downlink (DL) NAS message that comprises a cause value indicating that the SM message was not forwarded due to routing failure; and wherein an indication that the SM message was not forwarded due to routing failure is transferred, from a lower sublayer of the UE to an upper sublayer of the UE, based on the cause value, wherein the SM message is generated in the upper sublayer of the UE and is provided to the lower sublayer of the UE, and wherein the UL NAS message comprising the SM message is sent to the AMF by the lower sublayer of the UE. ### Claim 12 (depends on 11) The AMF of claim 11, wherein the upper sublayer of the UE is a Session Management (SM) sublayer that performs protocol data unit (PDU) session control, and wherein the lower sublayer of the UE is a Mobility Management (MM) sublayer that performs mobility control of the UE. ### Claim 13 (depends on 11) The AMF of claim 11, wherein a pre-configured timer is started by the UE, based on the upper sublayer of the UE providing the SM message to the lower sublayer of the UE; and wherein the pre-configured timer is stopped by the UE, and a procedure related to the SM message is stopped, based on the upper sublayer receiving, from the lower sublayer, the indication that the SM message was not forwarded due to routing failure. ### Claim 14 (depends on 13) The AMF of claim 13, wherein at least one retransmission of the SM message is performed by the UE, based on the pre-configured timer expiring, and a procedure related to the SM message is stopped by the UE, based on failure of the at least one re-transmission of the SM message. ### Claim 15 (depends on 11) The AMF of claim 11, wherein the UL NAS message further comprises a data network name (DNN) or single network slice selection assistance information (S-NSSAI) for the selection of a session management function (SMF) to forward the SM message. ### Claim 16 (depends on 12) The AMF of claim 12, wherein based on the SM message being a message requesting an establishment of a PDU session, the UL NAS message further comprises a PDU session identifier (ID) for the PDU session to which the establishment is requested. ### Claim 17 (depends on 11) The AMF of claim 11, wherein the lower sublayer forwards, to the upper sublayer, information about whether the SM message not being forwarded due to routing failure is permanent or temporary, together with the indication. ### Claim 18 (depends on 17) The AMF of claim 17, wherein based on the SM message not being forwarded due to routing failure being permanent, the upper sublayer performs a release procedure for a PDU session or a data network (DN) related to the SM message. ### Claim 19 (depends on 18) The AMF of claim 18, wherein the upper sublayer includes the PDU session or the DN in a procedure forbidden list and manages the PDU session or the DN. ### Claim 20 (depends on 18) The AMF of claim 18, wherein based on services related to the PDU session or the DN being required, the upper sublayer requests a deregistration to the lower sublayer.